Reprint of: Effects of solution degassing on solubility, crystal growth and dissolution-Case study: Salicylic acid in methanol

NASA Astrophysics Data System (ADS)

Seidel, J.; Ulrich, J.

2017-07-01

The influence of dissolved gases on the crystallization parameter solubility, MZW, growth and dissolution rates was investigated experimentally using degassed and non-degassed (air-saturated) solutions. The results of this study show that degassing has no effect on the solubility curve of the used model substance salicylic acid (SA) in methanol (MeOH). This reveals in the assumption that a thermodynamic effect of dissolved gases can be excluded. Growth rates were measured by means of a desupersaturation method and the results indicate that the growth rates of SA are not affected by degassing. The results of the dissolution rate measurements reveal a distinct decrease in dissolution rates for non-degassed solutions compared to degassed solutions, especially, at low temperature (10 °C). To explain this phenomenon the gas solubility, represented by oxygen, in MeOH in dependence on the SA concentration was estimated by means of Hansen Solubility Parameters (HSP) [1]. It was found that the oxygen solubility decreases with increasing SA content which explains the inhibition of crystal dissolution in non-degassed solution compared to degassed solution. Moreover, this kind of 'drowing-out' mechanism would not appear in growth rate measurements, where indeed no effect of degassing could be observed.

Effects of solution degassing on solubility, crystal growth and dissolution-Case study: Salicylic acid in methanol

NASA Astrophysics Data System (ADS)

Seidel, J.; Ulrich, J.

2017-02-01

The influence of dissolved gases on the crystallization parameter solubility, MZW, growth and dissolution rates was investigated experimentally using degassed and non-degassed (air-saturated) solutions. The results of this study show that degassing has no effect on the solubility curve of the used model substance salicylic acid (SA) in methanol (MeOH). This reveals in the assumption that a thermodynamic effect of dissolved gases can be excluded. Growth rates were measured by means of a desupersaturation method and the results indicate that the growth rates of SA are not affected by degassing. The results of the dissolution rate measurements reveal a distinct decrease in dissolution rates for non-degassed solutions compared to degassed solutions, especially, at low temperature (10 °C). To explain this phenomenon the gas solubility, represented by oxygen, in MeOH in dependence on the SA concentration was estimated by means of Hansen Solubility Parameters (HSP) [1]. It was found that the oxygen solubility decreases with increasing SA content which explains the inhibition of crystal dissolution in non-degassed solution compared to degassed solution. Moreover, this kind of 'drowing-out' mechanism would not appear in growth rate measurements, where indeed no effect of degassing could be observed.

Protein-protein interactions during high-moisture extrusion for fibrous meat analogues and comparison of protein solubility methods using different solvent systems.

PubMed

Liu, KeShun; Hsieh, Fu-Hung

2008-04-23

Soy protein, mixed with gluten and starch, was extruded into fibrous meat analogues under high-moisture and high-temperature conditions. The protein solubility of samples collected at different extruder zones and extrudates made with different moistures was determined by 11 extraction solutions consisting of 6 selective reagents and their combinations: phosphate salts, urea, DTT, thiourea, Triton X-100, and CHAPS. Protein solubility by most extractants showed decreasing patterns as the material passed through the extruder, but the solution containing all 6 reagents, known as isoelectric focus (IEF) buffer, solubilized the highest levels and equal amounts of proteins in all samples, indicating that there are no other covalent bonds involved besides disulfide bonds. With regard to relative importance between disulfide bonds and non-covalent interactions, different conclusions could be made from protein solubility patterns, depending on the type of extracting systems and a baseline used for comparison. The observation points out pitfalls and limitation of current protein solubility methodology and explains why controversy exists in the literature. Using the IEF buffer system with omission of one or more selective reagents is considered to be the right methodology to conduct protein solubility study and thus recommended. Results obtained with this system indicate that disulfide bonding plays a more important role than non-covalent bonds in not only holding the rigid structure of extrudates but also forming fibrous texture. The sharpest decrease in protein solubility occurred when the mix passed through the intermediate section of the extruder barrel, indicating formation of new disulfide bonds during the stage of dramatic increase in both temperature and moisture. After this stage, although the physical form of the product might undergo change and fiber formation might occur as it passed through the cooling die, the chemical nature of the product did not change significantly.

Water clustering in glassy polymers.

PubMed

Davis, Eric M; Elabd, Yossef A

2013-09-12

In this study, water solubility and water clustering in several glassy polymers, including poly(methyl methacrylate) (PMMA), poly(styrene) (PS), and poly(vinylpyrrolidone) (PVP), were measured using both quartz spring microbalance (QSM) and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Specifically, QSM was used to determine water solubility, while FTIR-ATR spectroscopy provided a direct, molecular-level measurement of water clustering. The Flory-Huggins theory was employed to obtain a measure of water-polymer interaction and water solubility, through both prediction and regression, where the theory failed to predict water solubility in both PMMA and PVP. Furthermore, a comparison of water clustering between direct FTIR-ATR spectroscopy measurements and predictions from the Zimm-Lundberg clustering analysis produced contradictory results. The failure of the Flory-Huggins theory and Zimm-Lundberg clustering analysis to describe water solubility and water clustering, respectively, in these glassy polymers is in part due to the equilibrium constraints under which these models are derived in contrast to the nonequilibrium state of glassy polymers. Additionally, FTIR-ATR spectroscopy results were compared to temperature-dependent diffusivity data, where a correlation between the activation energy for diffusion and the measured water clustering was observed.

Release of volatile mercury from vascular plants

NASA Technical Reports Server (NTRS)

Siegel, S. M.; Puerner, N. J.; Speitel, T. W.

1974-01-01

Volatile, organic solvent soluble mercury has been found in leaves and seeds of several angiosperms. Leaves of garlic vine, avocado, and haole-koa release mercury in volatile form rapidly at room temperature. In garlic vine, the most active release is temperature dependent, but does not parallel the vapor-pressure temperature relationship for mercury. Mercury can be trapped in nitric-perchloric acid digestion fluid, or n-hexane, but is lost from the hexane unless the acid mixture is present. Seeds of haole-koa also contain extractable mercury but volatility declines in the series n-hexane (90%), methanol (50%), water (10%). This suggests that reduced volatility may accompany solvolysis in the more polar media.

Solubility of crystalline organic compounds in high and low molecular weight amorphous matrices above and below the glass transition by zero enthalpy extrapolation.

PubMed

Amharar, Youness; Curtin, Vincent; Gallagher, Kieran H; Healy, Anne Marie

2014-09-10

Pharmaceutical applications which require knowledge of the solubility of a crystalline compound in an amorphous matrix are abundant in the literature. Several methods that allow the determination of such data have been reported, but so far have only been applicable to amorphous polymers above the glass transition of the resulting composites. The current work presents, for the first time, a reliable method for the determination of the solubility of crystalline pharmaceutical compounds in high and low molecular weight amorphous matrices at the glass transition and at room temperature (i.e. below the glass transition temperature), respectively. The solubilities of mannitol and indomethacin in polyvinyl pyrrolidone (PVP) K15 and PVP K25, respectively were measured at different temperatures. Mixtures of undissolved crystalline solute and saturated amorphous phase were obtained by annealing at a given temperature. The solubility at this temperature was then obtained by measuring the melting enthalpy of the crystalline phase, plotting it as a function of composition and extrapolating to zero enthalpy. This new method yielded results in accordance with the predictions reported in the literature. The method was also adapted for the measurement of the solubility of crystalline low molecular weight excipients in amorphous active pharmaceutical ingredients (APIs). The solubility of mannitol, glutaric acid and adipic acid in both indomethacin and sulfadimidine was experimentally determined and successfully compared with the difference between their respective calculated Hildebrand solubility parameters. As expected from the calculations, the dicarboxylic acids exhibited a high solubility in both amorphous indomethacin and sulfadimidine, whereas mannitol was almost insoluble in the same amorphous phases at room temperature. This work constitutes the first report of the methodology for determining an experimentally measured solubility for a low molecular weight crystalline solute in a low molecular weight amorphous matrix. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: I. Iron-copper-zinc-lead sulfide solubility relations

USGS Publications Warehouse

Hemley, J.J.; Cygan, G.L.; Fein, J.B.; Robinson, G.R.; d'Angelo, W. M.

1992-01-01

Experimental studies, using cold-seal and extraction vessel techniques, were conducted on Fe, Pb, Zn, and Cu sulfide solubilities in chloride soultions at temperatures from 300?? to 700??C and pressures from 0.5 to 2 kbars. The solutions were buffered in pH by quartz monzonite and the pure potassium feldspar-muscovite-quartz assemblage and in fS2-fO2 largely by the assemblage pyrite-pyrrhotite-magnetite. Solubilities increase with increasing temperature and total chloride, and decrease with increasing pressure. The effect of increasing chloride concentration on solubility reflects primarily a shift to lower pH via the silicate buffer reactions. Similarity in behaviour with respect to the temperature and pressure of Fe, Zn, and Pb sulfide solubilities points to similarity in chloride speciation, and the neutral species appear to be dominant in the high-temperature region. -from Authors

The solubility of gold in hydrogen sulfide gas: An experimental study

NASA Astrophysics Data System (ADS)

Zezin, Denis Yu.; Migdisov, Artashes A.; Williams-Jones, Anthony E.

2007-06-01

The solubility of gold in H 2S gas has been investigated at temperatures of 300, 350 and 400 °C and pressures up to 230 bars. Experimentally determined values of the solubility of Au are 0.4-1.4 ppb at 300 °C, 1-8 ppb at 350 °C and 8.6-95 ppb at 400 °C. Owing to a positive dependence of the logarithm of the fugacity of gold on the logarithm of the fugacity of H 2S, it is proposed that the solubility of Au can be attributed to formation of a solvated gaseous sulfide or bisulfide complex through reactions of the type: Au(s)+(n+1)·HS(g)=AuS·(HS)n(g)+H(g) or Au(g)+(n+1)·HS(g)=AuHS·(HS)n(g)+{1}/{2}H(g) which are f-dependent; n is a statistical solvation number. If the redox potential is buffered by S/H 2S (the case in our study), the corresponding reactions are: Au(s)+n·HS(g)+S(l)=AuS·(HS)n(g) or Au(s)+(n+{1}/{2})·HS(g)+{1}/{2}S(l)=AuHS·(HS)n(g) Values of n for these latter reactions were calculated to be 1.8 and 1.2 at 300 °C, 1.7 and 1.0 at 350 °C, 2.2 and 1.7 at 400 °C, respectively. The equilibrium constants for reactions 3 and D increase with temperature and have values of log K = -11.1 ± 0.2 at 300 °C (both reactions), -10.7 ± 0.3 and -10.5 ± 0.3 at 350 °C, and -10.6 ± 0.2 and -10.4 ± 0.2 at 400 °C, respectively. At the conditions of this study, the solubility of gold in H 2S gas is relatively high, and the results obtained provide strong evidence that H 2S can play an important role in the vapor transport of gold and the formation of hydrothermal gold deposits.

Low-molecular-weight gelators: elucidating the principles of gelation based on gelator solubility and a cooperative self-assembly model.

PubMed

Hirst, Andrew R; Coates, Ian A; Boucheteau, Thomas R; Miravet, Juan F; Escuder, Beatriu; Castelletto, Valeria; Hamley, Ian W; Smith, David K

2008-07-16

This paper highlights the key role played by solubility in influencing gelation and demonstrates that many facets of the gelation process depend on this vital parameter. In particular, we relate thermal stability ( T gel) and minimum gelation concentration (MGC) values of small-molecule gelation in terms of the solubility and cooperative self-assembly of gelator building blocks. By employing a van't Hoff analysis of solubility data, determined from simple NMR measurements, we are able to generate T calc values that reflect the calculated temperature for complete solubilization of the networked gelator. The concentration dependence of T calc allows the previously difficult to rationalize "plateau-region" thermal stability values to be elucidated in terms of gelator molecular design. This is demonstrated for a family of four gelators with lysine units attached to each end of an aliphatic diamine, with different peripheral groups (Z or Boc) in different locations on the periphery of the molecule. By tuning the peripheral protecting groups of the gelators, the solubility of the system is modified, which in turn controls the saturation point of the system and hence controls the concentration at which network formation takes place. We report that the critical concentration ( C crit) of gelator incorporated into the solid-phase sample-spanning network within the gel is invariant of gelator structural design. However, because some systems have higher solubilities, they are less effective gelators and require the application of higher total concentrations to achieve gelation, hence shedding light on the role of the MGC parameter in gelation. Furthermore, gelator structural design also modulates the level of cooperative self-assembly through solubility effects, as determined by applying a cooperative binding model to NMR data. Finally, the effect of gelator chemical design on the spatial organization of the networked gelator was probed by small-angle neutron and X-ray scattering (SANS/SAXS) on the native gel, and a tentative self-assembly model was proposed.

Solubility of Aragonite in Subduction Water-Rich Fluids

NASA Astrophysics Data System (ADS)

Daniel, I.; Facq, S.; Petitgirard, S.; Cardon, H.; Sverjensky, D. A.

2017-12-01

Carbonate dissolution in subduction zone fluids is critical to the carbon budget in subduction zones. Depending on the solubility of carbonate minerals in aqueous fluids, the subducting lithosphere may be either strongly depleted and the mantle metasomatized if the solubility is high, as recently suggested by natural samples or transport carbon deeper into the Earth's mantle if the solubility is low enough [1, 2]. Dissolution of carbonate minerals strongly depends on pressure and temperature as well as on the chemistry of the fluid, leading to a highly variable speciation of aqueous carbon. Thanks to recent advances in theoretical aqueous geochemistry [3, 4], combined experimental and theoretical efforts now allow the investigation of speciation and solubility of carbonate minerals in aqueous fluids at PT conditions higher than previously feasible [4, 5]. In this study, we present new in situ X-ray fluorescence measurements of aragonite dissolution up to 5 GPa and 500°C and the subsequent thermodynamic model of aragonite solubility in aqueous fluids thanks to the Deep Earth Water model. The amount of dissolved aragonite in the fluid was calculated from challenging and unprecedented measurements of the Ca fluorescence K-lines at low-energy. Experiments were performed at the ESRF, beamline ID27 using a dedicated design of an externally-heated diamond anvil cell and an incident high-flux and highly focused monochromatic X-Ray beam at 20 keV. The results show a spectacularly high solubility of aragonite at HP-HT in water, further enhanced in presence of NaCl and silica in the solution. [1] Frezzotti, M. L. et al. (2011) doi:10.1038/ngeo1246. [2] Ague, J. J. and Nicolescu, S. (2014) doi:10.1038/ngeo2143. [3] Pan, D. et al. (2013) doi: 10.1073/pnas.1221581110. [4] Sverjensky, D. A et al. (2014) doi: 10.1016/j.gca.2013.12.019. [5] Facq, S. et al. (2014) doi: 10.1016/j.gca.2014.01.030.

The solubility of noble gases in crude oil at 25-100°C

USGS Publications Warehouse

Kharaka, Yousif K.; Specht, Daniel J.

1988-01-01

The solubility of the noble gases He, Ne, Ar, Kr and Xe was measured in two typical crude oils at temperatures of 25–100°C. The oil samples were obtained from the Elk Hills oil field located in southern San Joaquin Valley, California. The experimental procedure consisted of placing a known amount of gas with a known volume of crude oil in a stainless steel hydrothermal pressure vessel. The vessel was housed inside an oven and the entire unit rotates providing continuous mixing. The amount of gas dissolved in oil at a measured temperature and partial pressure of gas was used to calculate the solubility constants for these gases. Results show that the solubility of He and Ne in both oils is approximately the same; solubility then increases with atomic mass, with the solubility of Xe at 25°C being two orders of magnitude higher than that of He. The gas solubilities are somewhat higher in the lower density (higher API gravity) oil. The solubility of Ar is approximately constant in the range of temperatures of this study. The solubilities of He and Ne increase, but those of Kr and Xe decrease with increasing temperatures. Solubilities of noble gases in crude oil are significantly higher than their solubilities in water. For example, the solubilities of He and Xe at 25°C in the light oil of this study are, respectively, 3 and 24 times higher than their solubilities in pure water, and they are 15 and 300 times higher than in a brine with a salinity of 350,000 mg/l dissolved solids. These large and variable differences in the solubilities of noble gases in oil and water indicate that, in sedimentary basins with oil, these gases must be partitioned between oil, water and natural gas before they are used to deduce the origin and residence time of these fluids.

Towards an understanding of the molecular mechanism of solvation of drug molecules: a thermodynamic approach by crystal lattice energy, sublimation, and solubility exemplified by paracetamol, acetanilide, and phenacetin.

PubMed

Perlovich, German L; Volkova, Tatyana V; Bauer-Brandl, Annette

2006-10-01

Temperature dependencies of saturated vapor pressure for the monoclinic modification of paracetamol (acetaminophen), acetanilide, and phenacetin (acetophenetidin) were measured and thermodynamic functions of sublimation calculated (paracetamol: DeltaGsub298=60.0 kJ/mol; DeltaHsub298=117.9+/-0.7 kJ/mol; DeltaSsub298=190+/-2 J/mol.K; acetanilide: DeltaGsub298=40.5 kJ/mol; DeltaHsub298=99.8+/-0.8 kJ/mol; DeltaSsub298=197+/-2 J/mol.K; phenacetin: DeltaGsub298=52.3 kJ/mol; DeltaHsub298=121.8+/-0.7 kJ/mol; DeltaSsub298=226+/-2 J/mol.K). Analysis of packing energies based on geometry optimization of molecules in the crystal lattices using diffraction data and the program Dmol3 was carried out. Parameters analyzed were: (a) energetic contribution of van der Waals forces and hydrogen bonding to the total packing energy; (b) contributions of fragments of the molecules to the packing energy. The fraction of hydrogen bond energy in the packing energy increases as: phenacetin (17.5%)

IUPAC-NIST Solubility Data Series. 75. Nonmetals in Liquid Alkali Metals

NASA Astrophysics Data System (ADS)

Borgstedt, Hans Ulrich; Guminski, Cezary; Borgstedt, Hans Ulrich; Guminski, Cezary

2001-07-01

Liquid alkali metals have several physical properties which favor their use in a number of important applications. For example, their large liquidus temperature range and their excellent heat transfer properties are important for use as heat transfer media. They are used in large nuclear reactors in which hundreds of tons of sodium are circulating, and in small parts of engines for cooling of valves. Since these metals are among the most electropositive elements, several of them (Li, Na) can be used in high specific capacity and high energy density batteries at moderately elevated temperatures. The compatibility of metallic constructional materials which are used to contain the liquid metals is strongly influenced by nonmetals present in the liquids. The physical properties of the liquid metals are also influenced by dissolved substances. Several nonmetals dissolved in alkali metals are able to form ternary compounds with components of the constructional materials. Thus, corrosion and compatibility studies have been accompanied by extensive chemical work related to the solutions of non-metallic substances in liquid alkali metals. All available solubility data of nonmetallic elements and some of their compounds in the five liquid alkali metal solvents (Li, Na, K, Rb, and Cs) are collected and compiled. Original publications with reliable data and information on the methods used to generate them are reported in individual Compilations. When numerical data are not given in a publication, the data are often read out from figures and converted into numerical data by the compilers. The precision of this procedure is indicated in the Compilations under Estimated Error. Evaluated solubility data are tabulated at the end of the Critical Evaluations: if there is agreement of at least two independent studies within the experimental error, the solubility values are assigned to the "recommended" category. Values are assigned as "tentative," if only one reliable result was reported, or if the mean value of two or more reliable studies was outside the error limits. In the tabulation, three, two, or one significant figures are assigned for respective precisions that are better than ±1% and ±10% and worse than ±10%. If necessary, the solubilities are recalculated into mol %. The completeness of this investigation of the literature has been confirmed and extended by studying several reviews dealing with the solution chemistry of substances in the alkali metals. Solubility data are sometimes measured under parameters, which are not standard conditions of such measurements. Frequently measurements are performed under constrained pressure. The solubility of noble gases or other gases, which do not form compounds with the alkali metals, depends on the gas pressures. This dependency is documented in the data sheets. Schematic phase diagrams are presented in systems for which they assist the understanding of the data and the conclusions. They are based on the most recent state of knowledge and generally presented in the Critical Evaluations. Some solubility diagrams are shown in form of a log solubility versus reciprocal temperature function. These figures illustrate the larger scatter of data for systems in which interfering reactions cause unstable behavior of solutions. While several solutes are well defined substances, other systems need still additional studies to define the equilibrium solid state compound. One should realize that estimations of the stoichiometry and thermal stability of ternary compounds are experimentally difficult, and their results are often uncertain.

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

Saha, Pritam; Anderson, Alan J.; Lee, Thomas

The solubility of tugarinovite (MoO 2) in pure water was investigated at temperatures between 400 and 800°C and at pressures ranging between 95 and 480 MPa by using in situ synchrotron X-ray fluorescence (SXRF) to separately analyze high temperature aqueous solutions in a hydrothermal diamond anvil cell (HDAC). The concentration of molybdenum in the fluid at 400 and 500°C was below detection; however, at temperatures between 600 and 800°C, the solubility of tugarinovite increased with increasing temperature by two orders of magnitude. The molybdenum concentration at 600°C and 800°C is 44 ppm and 658 ppm, respectively. The results complement themore » data of Kudrin (1985) and provide the first measurement of MoO 2solubility at pressure and temperature conditions comparable to intrusion-related Mo deposit formation. The data are also relevant to the study of water chemistry and corrosion product transport in supercritical-water-cooled reactors, where Mo-bearing steel alloys interact with aqueous solutions at temperatures greater than 600°C. The application of in situ SXRF to solubility measurements of sparingly soluble minerals is recommended because it circumvents analytical uncertainties inherent in determinations obtained by quenching and weight loss measurements.« less

Measured solubilities and speciations from oversaturation experiments of neptunium, plutonium, and americium in UE-25p No. 1 well water from the Yucca Mountain region: Milestone report 3329-WBS1.2.3.4.1.3.1

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

Nitsche, H.; Roberts, K.; Prussin, T.

1994-04-01

Solubility and speciation are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are a part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, and {sup 241}Am{sup 3+}/Nd{sup 3+} in a modified UE-25p No. 1 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at two different temperatures (25{degree}more » and 60{degree}C) and three pH values (6.0, 7.0, 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations significantly decreased with increasing temperature at pH 6 and 7. The concentration at pH 8.5 hardly decreased at all with increasing temperature. At both temperatures the concentrations were highest at pH 8.5, lowest at pH 7, and in between at pH 6. For the americium/neodymium solutions, the solubility decreased significantly with increasing temperature and increased somewhat with increasing pH.« less

High-yield soluble expression, purification and characterization of human steroidogenic acute regulatory protein (StAR) fused to a cleavable Maltose-Binding Protein (MBP).

PubMed

Sluchanko, Nikolai N; Tugaeva, Kristina V; Faletrov, Yaroslav V; Levitsky, Dmitrii I

2016-03-01

Steroidogenic acute regulatory protein (StAR) is responsible for the rapid delivery of cholesterol to mitochondria where the lipid serves as a source for steroid hormones biosynthesis in adrenals and gonads. Despite many successful investigations, current understanding of the mechanism of StAR action is far from being completely clear. StAR was mostly obtained using denaturation/renaturation or in minor quantities in a soluble form at decreased temperatures that, presumably, limited the possibilities for its consequent detailed exploration. In our hands, existing StAR expression constructs could be bacterially expressed almost exclusively as insoluble forms, even upon decreased expression temperatures and in specific strains of Escherichia coli, and isolated protein tended to aggregate and was difficult to handle. To maximize the yield of soluble protein, optimized StAR sequence encompassing functional domain STARD1 (residues 66-285) was fused to the C-terminus of His-tagged Maltose-Binding Protein (MBP) with the possibility to cleave off the whole tag by 3C protease. The developed protocol of expression and purification comprising of a combination of subtractive immobilized metal affinity chromatography (IMAC) and size-exclusion chromatography allowed us to obtain up to 25 mg/1 L culture of completely soluble StAR protein, which was (i) homogenous according to SDS-PAGE, (ii) gave a single symmetrical peak on a gel-filtration, (iii) showed the characteristic CD spectrum and (iv) pH-dependent ability to bind a fluorescently-labeled cholesterol analogue. We conclude that our strategy provides fully soluble and native StAR protein which in future could be efficiently used for biotechnology and drug discovery aimed at modulation of steroids production. Copyright © 2015 Elsevier Inc. All rights reserved.

A quantitative model to evaluate solubility relationship of polymorphs from their thermal properties.

PubMed

Mao, Chen; Pinal, Rodolfo; Morris, Kenneth R

2005-07-01

The objective of the study is to develop a model to estimate the solubility ratio of two polymorphic forms based on the calculation of the free energy difference of two forms at any temperature. This model can be used for compounds with low solubility (a few mole percent) in which infinite dilution can be approximated. The model is derived using the melting temperature and heat of fusion for apparent monotropic systems, and the solid-solid transition temperature and heat of transition for apparent enantiotropic systems. A rigorous derivation also requires heat capacity (Cp) measurement of liquid and two solid forms. This model is validated by collecting thermal properties of polymorphs for several drugs using conventional or modulated differential scanning calorimetry. From these properties the solubility ratio of two polymorphs is evaluated using the model and compared with the experimental value at different temperatures. The predicted values using the full model agree well with the experimental ones. For the purpose of easy measurement, working equations without Cp terms are also applied. Ignoring Cp may result in an error of 10% or less, suggesting that the working equation is applicable in practice. Additional error may be generated for the apparent enantiotropic systems due to the inconsistency between the observed solid-solid transition temperature and the true thermodynamic transition temperature. This inconsistency allows the predicted solubility ratios (low melt/high melt) to be smaller. Therefore, a correction factor of 1.1 is recommended to reduce the error when the working equation is used to estimate the solubility ratio of an enantiotropic system. The study of the free energy changes of two crystalline forms of a drug allows for the development of a model that successfully predicts the solubility ratio at any temperature from their thermal properties. This model provides a thermodynamic foundation as to how the free energy difference of two polymorphs is reflected by their equilibrium solubilities. It also provides a quick and practical way of evaluating the relative solubility of two polymorphs from single differential scanning calorimetry runs.

pH-dependent solubility of indomethacin-saccharin and carbamazepine-saccharin cocrystals in aqueous media.

PubMed

Alhalaweh, Amjad; Roy, Lilly; Rodríguez-Hornedo, Naír; Velaga, Sitaram P

2012-09-04

Cocrystals constitute an important class of pharmaceutical solids for their remarkable ability to modulate solubility and pH dependence of water insoluble drugs. Here we show how cocrystals of indomethacin-saccharin (IND-SAC) and carbamazepine-saccharin (CBZ-SAC) enhance solubility and impart a pH-sensitivity different from that of the drugs. IND-SAC exhibited solubilities 13 to 65 times higher than IND at pH values of 1 to 3, whereas CBZ-SAC exhibited a 2 to 10 times higher solubility than CBZ dihydrate. Cocrystal solubility dependence on pH predicted from mathematical models using cocrystal K(sp), and cocrystal component K(a) values, was in excellent agreement with experimental measurements. The cocrystal solubility increase relative to drug was predicted to reach a limiting value for a cocrystal with two acidic components. This limiting value is determined by the ionization constants of cocrystal components. Eutectic constants are shown to be meaningful indicators of cocrystal solubility and its pH dependence. The two contributions to solubility, cocrystal lattice and solvation, were evaluated by thermal and solubility determinations. The results show that solvation is the main barrier for the aqueous solubility of these drugs and their cocrystals, which are orders of magnitude higher than their lattice barriers. Cocrystal increase in solubility is thus a result of decreasing the solvation barrier compared to that of the drug. This work demonstrates the favorable properties of cocrystals and strategies that facilitate their meaningful characterization.

Carbon dioxide solubility in aqueous solutions of sodium chloride at geological conditions: Experimental results at 323.15, 373.15, and 423.15 K and 150 bar and modeling up to 573.15 K and 2000 bar

NASA Astrophysics Data System (ADS)

Zhao, Haining; Fedkin, Mark V.; Dilmore, Robert M.; Lvov, Serguei N.

2015-01-01

A new experimental system was designed to measure the solubility of CO2 at pressures and temperatures (150 bar, 323.15-423.15 K) relevant to geologic CO2 sequestration. At 150 bar, new CO2 solubility data in the aqueous phase were obtained at 323.15, 373.15, and 423.15 K from 0 to 6 mol kg-1 NaCl(aq) for the CO2-NaCl-H2O system. A γ - φ (activity coefficient - fugacity coefficient) type thermodynamic model is presented for the calculation of both the solubility of CO2 in the aqueous phase and the solubility of H2O in the CO2-rich phase for the CO2-NaCl-H2O system. Validation of the model calculations against literature data and other models (MZLL2013, AD2010, SP2010, DS2006, and OLI) show that the proposed model is capable of predicting the solubility of CO2 in the aqueous phase for the CO2-H2O and CO2-NaCl-H2O systems with a high degree of accuracy (AAD <3.9%) at temperatures from 273.15 to 573.15 K and pressures up to 2000 bar. A comparison of modeling results with experimental values revealed a pressure-bounded "transition zone" in which the CO2 solubility decreases to a minimum then increases as the temperature increases. CO2 solubility is not a monotonic function of temperature in the transition zone but outside of that transition zone, the CO2 solubility is decrease or increase monotonically in response to increased temperature. A link of web-based CO2 solubility computational tool can be provided by sending a message to Haining Zhao at hzz5047@gmail.com.

Measured solubilities and speciations of neptunium, plutonium, and americium in a typical groundwater (J-13) from the Yucca Mountain region; Milestone report 3010-WBS 1.2.3.4.1.3.1

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

Nitsche, H.; Gatti, R.C.; Standifer, E.M.

1993-07-01

Solubility and speciation data are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, {sup 241}Am{sup 3+}/Nd{sup 3+}, and {sup 243}Am{sup 3+} in J-13 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at three different temperatures (25{degree}, 60{degree},more » and 90{degree}C) and pH values (5.9, 7.0, and 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations decreased with increasing temperature and showed no trend with pH. The americium solutions showed no clear solubility trend with increasing temperature and increasing pH.« less

[Characterization of polygalacturonase covalently bonded to Sepharose].

PubMed

Bock, W; Krause, M; Anger, H; Flemming, C

1981-01-01

For the soluble endo-polygalacturonase (EC 3.2.1.15.) from Aspergillus spec., investigated in the present work, the defined substrate turnover U at 50% loss of viscosity if 0.2% and is independent on the reaction temperature. In the case of the covalently-bonded enzyme, the following linear equation applies to U, depending on the specific activity A and in the limits from A = O [U] and Amax: U = [U] + S square root of A. U is influenced by the kind of linkage, the conditions of immobilization and the properties of the carrier: it is a measure of the postulated conformational change of the polygalacturonase. The characteristic limiting value for the substrate turnover at A = O [U] is also temperature-independent and proves to be a true increment of binding, whereas Amax depends essentially on the porosity of the carrier. Polygalacturonase-sepharose complexes with a real substrate turnover U of 3--20% were prepared by varying systematically the kind of linkage and the specific activity A. It was found that with increasing U these complexes were, as a rule, inhibited to a lesser extent by a non-competitive pectinase inhibitor than the soluble polygalacturonase. Furthermore, their ability to liberate or enrich oligomeric galacturonic acids with a degree of polymerization greater than 3 was markedly reduced.

Zirconium-based alloys, nuclear fuel rods and nuclear reactors including such alloys, and related methods

DOEpatents

Mariani, Robert Dominick

2014-09-09

Zirconium-based metal alloy compositions comprise zirconium, a first additive in which the permeability of hydrogen decreases with increasing temperatures at least over a temperature range extending from 350.degree. C. to 750.degree. C., and a second additive having a solubility in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. At least one of a solubility of the first additive in the second additive over the temperature range extending from 350.degree. C. to 750.degree. C. and a solubility of the second additive in the first additive over the temperature range extending from 350.degree. C. to 750.degree. C. is higher than the solubility of the second additive in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. Nuclear fuel rods include a cladding material comprising such metal alloy compositions, and nuclear reactors include such fuel rods. Methods are used to fabricate such zirconium-based metal alloy compositions.

Solubilities of inert gases and methane in H2O and in D2O in the temperature range of 300 to 600 K

NASA Astrophysics Data System (ADS)

Crovetto, Rosa; Fernández-Prini, R.; Japas, María Laura

1982-01-01

The solubility of inert gases and methane in H2O and D2O has been measured between room temperature and 600 K. The calculation of Henry's constants kH, from the solubility data is analyzed in detail; if due account is taken of the nonideality in the gas phase, they can be determined unambiguously up to 520 K. Above this temperature, the ambiguity in kH increases sharply as contributions of third and higher order virial coefficients to the equation of state of the gaseous mixture become more important. The differences of gas solubilities in light and heavy water essentially disappear above the temperature of minimum solubility of the gases. The characteristic thermodynamic features of the aqueous solutions of gases (i.e., large values of -ΔS02 and of ΔC0p2) are still present at 520 K. It is shown that mean-field theories can account for the

Potassium alum and aluminum sulfate micro-inclusions in polar ice from Dome Fuji, East Antarctica

NASA Astrophysics Data System (ADS)

Ohno, Hiroshi; Iizuka, Yoshinori; Horikawa, Shinichiro; Sakurai, Toshimitsu; Hondoh, Takeo; Motoyama, Hideaki

2014-03-01

Water-soluble trace constituents affect the physicochemical properties of polar ice. Their structural distribution provides important insights into the formation history of ice and inclusions. We report the first finding of KAl(SO4)2·12H2O (potassium alum) and Al2(SO4)3·nH2O (aluminum sulfate) micro-inclusions in the Dome Fuji ice core, East Antartica, using a micro-Raman technique. Eutectic temperatures of these water-soluble species determined using thermal analysis were -0.4 °C for potassium alum and -8.0 °C for aluminum sulfate. Although the formation process of the aluminum-bearing sulfates remains unclear, the occurrence of these salts largely depends on ice depth.

Solubility and precipitation of nicotinic acid in supercritical carbon dioxide.

PubMed

Rehman, M; Shekunov, B Y; York, P; Colthorpe, P

2001-10-01

Solubilities of a model compound (nicotinic acid) in pure supercritical carbon dioxide (SC-CO(2)) and SC-CO(2) modified with methanol have been measured in the pressure range of 80-200 bar and between temperatures of 35 and 90 degrees C. On-line ultraviolet detection enabled a simple and relatively fast measurement of very low levels of solubility (10(-7) mol fraction) with good accuracy in pure and modified SC-CO(2). The solute solubility in both pure SC-CO(2) and SC-CO(2) modified with methanol increased with pressure at all investigated temperatures. A retrograde solubility behavior was observed in that, at pressures below 120 bar, a solubility decrease on temperature increase occurred. Solubility data were used to calculate supersaturation values and to define optimum operating conditions to obtain crystalline particles 1-5 microm in diameter using the solution-enhanced dispersion by supercritical fluids (SEDS) process, thereby demonstrating the feasibility of a one-step production process for particulate pharmaceuticals suitable for respiratory drug delivery. Copyright 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1570-1582, 2001

Solubility Measurements and Predictions of Gypsum, Anhydrite, and Calcite Over Wide Ranges of Temperature, Pressure, and Ionic Strength with Mixed Electrolytes

NASA Astrophysics Data System (ADS)

Dai, Zhaoyi; Kan, Amy T.; Shi, Wei; Zhang, Nan; Zhang, Fangfu; Yan, Fei; Bhandari, Narayan; Zhang, Zhang; Liu, Ya; Ruan, Gedeng; Tomson, Mason B.

2017-02-01

Today's oil and gas production from deep reservoirs permits exploitation of more oil and gas reserves but increases risks due to conditions of high temperature and high pressure. Predicting mineral solubility under such extreme conditions is critical for mitigating scaling risks, a common and costly problem. Solubility predictions use solubility products and activity coefficients, commonly from Pitzer theory virial coefficients. However, inaccurate activity coefficients and solubility data have limited accurate mineral solubility predictions and applications of the Pitzer theory. This study measured gypsum solubility under its stable phase conditions up to 1400 bar; it also confirmed the anhydrite solubility reported in the literature. Using a novel method, the virial coefficients for Ca2+ and {{SO}}4^{2 - } (i.e., β_{{{{CaSO}}4 }}^{(0)} ,β_{{{{CaSO}}4 }}^{(2)} ,C_{{{{CaSO}}4 }}^{φ }) were calculated over wide ranges of temperature and pressure (0-250 °C and 1-1400 bar). The determination of this set of virial coefficients widely extends the applicable temperature and pressure ranges of the Pitzer theory in Ca2+ and SO 4 2- systems. These coefficients can be applied to improve the prediction of calcite solubility in the presence of high concentrations of Ca2+ and SO 4 2- ions. These new virial coefficients can also be used to predict the solubilities of gypsum and anhydrite accurately. Moreover, based on the derived β_{{{{CaSO}}4 }}^{(2)} values in this study, the association constants of {{CaSO}}4^{( 0 )} at 1 bar and 25 °C can be estimated by K_{{assoc}} = - 2β_{{{{CaSO}}4 }}^{(2)}. These values match very well with those reported in the literature based on other methods.

Equations for calculating hydrogeochemical reactions of minerals and gases such as CO2 at high pressures and temperatures

USGS Publications Warehouse

Appelo, C.A.J.; Parkhurst, David L.; Post, V.E.A.

2014-01-01

Calculating the solubility of gases and minerals at the high pressures of carbon capture and storage in geological reservoirs requires an accurate description of the molar volumes of aqueous species and the fugacity coefficients of gases. Existing methods for calculating the molar volumes of aqueous species are limited to a specific concentration matrix (often seawater), have been fit for a limited temperature (below 60 °C) or pressure range, apply only at infinite dilution, or are defined for salts instead of individual ions. A more general and reliable calculation of apparent molar volumes of single ions is presented, based on a modified Redlich–Rosenfeld equation. The modifications consist of (1) using the Born equation to calculate the temperature dependence of the intrinsic volumes, following Helgeson–Kirkham–Flowers (HKF), but with Bradley and Pitzer’s expression for the dielectric permittivity of water, (2) using the pressure dependence of the extended Debye–Hückel equation to constrain the limiting slope of the molar volume with ionic strength, and (3) adopting the convention that the proton has zero volume at all ionic strengths, temperatures and pressures. The modifications substantially reduce the number of fitting parameters, while maintaining or even extending the range of temperature and pressure over which molar volumes can be accurately estimated. The coefficients in the HKF-modified-Redlich–Rosenfeld equation were fitted by least-squares on measured solution densities.The limiting volume and attraction factor in the Van der Waals equation of state can be estimated with the Peng–Robinson approach from the critical temperature, pressure, and acentric factor of a gas. The Van der Waals equation can then be used to determine the fugacity coefficients for pure gases and gases in a mixture, and the solubility of the gas can be calculated from the fugacity, the molar volume in aqueous solution, and the equilibrium constant. The coefficients for the Peng–Robinson equations are readily available in the literature.The required equations have been implemented in PHREEQC, version 3, and the parameters for calculating the partial molar volumes and fugacity coefficients have been added to the databases that are distributed with PHREEQC. The ease of use and power of the formulation are illustrated by calculating the solubility of CO2 at high pressures and temperatures, and comparing with well-known examples from the geochemical literature. The equations and parameterizations are suitable for wide application in hydrogeochemical systems, especially in the field of carbon capture and storage.

Equations for calculating hydrogeochemical reactions of minerals and gases such as CO2 at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Appelo, C. A. J.; Parkhurst, D. L.; Post, V. E. A.

2014-01-01

Calculating the solubility of gases and minerals at the high pressures of carbon capture and storage in geological reservoirs requires an accurate description of the molar volumes of aqueous species and the fugacity coefficients of gases. Existing methods for calculating the molar volumes of aqueous species are limited to a specific concentration matrix (often seawater), have been fit for a limited temperature (below 60 °C) or pressure range, apply only at infinite dilution, or are defined for salts instead of individual ions. A more general and reliable calculation of apparent molar volumes of single ions is presented, based on a modified Redlich-Rosenfeld equation. The modifications consist of (1) using the Born equation to calculate the temperature dependence of the intrinsic volumes, following Helgeson-Kirkham-Flowers (HKF), but with Bradley and Pitzer’s expression for the dielectric permittivity of water, (2) using the pressure dependence of the extended Debye-Hückel equation to constrain the limiting slope of the molar volume with ionic strength, and (3) adopting the convention that the proton has zero volume at all ionic strengths, temperatures and pressures. The modifications substantially reduce the number of fitting parameters, while maintaining or even extending the range of temperature and pressure over which molar volumes can be accurately estimated. The coefficients in the HKF-modified-Redlich-Rosenfeld equation were fitted by least-squares on measured solution densities. The limiting volume and attraction factor in the Van der Waals equation of state can be estimated with the Peng-Robinson approach from the critical temperature, pressure, and acentric factor of a gas. The Van der Waals equation can then be used to determine the fugacity coefficients for pure gases and gases in a mixture, and the solubility of the gas can be calculated from the fugacity, the molar volume in aqueous solution, and the equilibrium constant. The coefficients for the Peng-Robinson equations are readily available in the literature. The required equations have been implemented in PHREEQC, version 3, and the parameters for calculating the partial molar volumes and fugacity coefficients have been added to the databases that are distributed with PHREEQC. The ease of use and power of the formulation are illustrated by calculating the solubility of CO2 at high pressures and temperatures, and comparing with well-known examples from the geochemical literature. The equations and parameterizations are suitable for wide application in hydrogeochemical systems, especially in the field of carbon capture and storage.

Solubility of aqueous methane under metastable conditions: implications for gas hydrate nucleation.

PubMed

Guo, Guang-Jun; Rodger, P Mark

2013-05-30

To understand the prenucleation stage of methane hydrate formation, we measured methane solubility under metastable conditions using molecular dynamics simulations. Three factors that influence solubility are considered: temperature, pressure, and the strength of the modeled van der Waals attraction between methane and water. Moreover, the naturally formed water cages and methane clusters in the methane solutions are analyzed. We find that both lowering the temperature and increasing the pressure increase methane solubility, but lowering the temperature is more effective than increasing the pressure in promoting hydrate nucleation because the former induces more water cages to form while the latter makes them less prevalent. With an increase in methane solubility, the chance of forming large methane clusters increases, with the distribution of cluster sizes being exponential. The critical solubility, beyond which the metastable solutions spontaneously form hydrate, is estimated to be ~0.05 mole fraction in this work, corresponding to the concentration of 1.7 methane molecules/nm(3). This value agrees well with the cage adsorption hypothesis of hydrate nucleation.

Protein solubilities determined by a rapid technique and modification of that technique to a micro-method

NASA Technical Reports Server (NTRS)

Cacioppo, Elizabeth; Pusey, Marc Lee; Munson, Sibyl

1989-01-01

A simple, rapid method for determination of protein solubilities has been developed which is based upon maximization of the free solution volume to be brought into equilibrium. The tetragonal lysozome solubility diagram has been determined from pH 4.0 to 5.2 (0.1 M sodium acetate), 2-7 percent NaCl, 3-25 C, and portions of the orthorhombic solubility diagram using this technique. Both tetragonal and orthorhombic solubilities were found to increase smoothly with decreasing salt concentration and increasing temperature; no retrograde solubilities were observed. Using column volumes of 75, 300, and 900 microliters, identical tetragonal lysozyme solubility diagrams were obtained. Chymotrypsinogen solubilities have also been determined using this apparatus, being retrograde over the temperature range tested. It is noted that the primary limiting factor in reducing the crystalline volume is the minimum solution sample size needed to accurately quantitate the protein.

Efficient osmolyte-based procedure to increase expression level and solubility of infectious hematopoietic necrosis virus (IHNV) nucleoprotein in E. coli.

PubMed

Mohammadinezhad, Rezvan; Farahmand, Hamid; Jalali, Seyed Amir Hossein; Mirvaghefi, Alireza

2018-05-01

The nucleoprotein of infectious hematopoietic necrosis virus (IHNV) is considered as the main target antigen for detection of IHNV infection in salmonid fish. This study aimed at improving the expression and solubility of IHNV nucleoprotein (IHNV-NP) in E. coli expression system. The effects of several expression strategies including host strain type, protein expression temperature, heat-shock treatment prior to protein induction, and additives in the growth medium and in the cell lysis buffer were examined. Results showed that bacterial strain type had a great impact on protein expression level, whereas it was not effective in preventing protein aggregation. Production of soluble IHNV-NP was proportionally increased with decreased incubation temperature. Heat-shock treatment prior to protein induction did not change the percent of solubility. For cells grown at low temperature, the presence of additives in the lysis buffer enhanced the solubility of IHNV-NP up to 24%. The highest yield of soluble protein was obtained via incorporation of osmolytes in the growth medium of cells exposed to a mild salt stress, in the following order: sucrose > sorbitol > glycerol > glycine. Soluble protein obtained by the optimized condition was efficiently purified in high yield and successfully detected by two monoclonal antibodies in a sandwich ELISA. Taken together, a combination of proper host strain, low-temperature expression, and timely application of osmolytes in the growth medium provided sufficient quantities of soluble recombinant IHNV-NP that has the potential to be used for diagnostic purposes.

Crystal structure and physicochemical characterization of ambazone monohydrate, anhydrous, and acetate salt solvate.

PubMed

Muresan-Pop, Marieta; Braga, Dario; Pop, Mihaela M; Borodi, Gheorghe; Kacso, Irina; Maini, Lucia

2014-11-01

The crystal structures of the monohydrate and anhydrous forms of ambazone were determined by single-crystal X-ray diffraction (SC-XRD). Ambazone monohydrate is characterized by an infinite three-dimensional network involving the water molecules, whereas anhydrous ambazone forms a two-dimensional network via hydrogen bonds. The reversible transformation between the monohydrate and anhydrous forms of ambazone was evidenced by thermal analysis, temperature-dependent X-ray powder diffraction and accelerated stability at elevated temperature, and relative humidity (RH). Additionally, a novel ambazone acetate salt solvate form was obtained and its nature was elucidated by SC-XRD. Powder dissolution measurements revealed a substantial solubility and dissolution rate improvement of acetate salt solvated form in water and physiological media compared with ambazone forms. Also, the acetate salt solvate displayed good thermal and solution stability but it transformed to the monohydrate on storage at elevated temperature and RH. Our study shows that despite the requirement for controlled storage conditions, the acetate salt solvated form could be an alternative to ambazone when solubility and bioavailability improvement is critical for the clinical efficacy of the drug product. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Phase relationships and cation disorder in RE{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7+{delta}}, RE = Pr, Nd, Sm, Gd

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

Kramer, M.J.; Wu, H.; Dennis, K.W.

1995-12-31

Unlike Y123 which forms only a stoichiometric compound, the light arare earth elements (LRE) form a solid solution LRE{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7+{delta}} (LRE123ss), with increasing substitution of the LRE{sup 3+} for the Ba{sup 2+} as the ionic radii of the LRE increases. The sub-solidus phase relationships around the LRE123ss change for La, Pr and Nd, but are similar for Sm and Gd. However, the solubility limit decreases with decreasing ionic radii. In addition, the solubility limits for Sm and Gd are strongly influenced by PO{sub 2} during high temperature annealing. The range of solubility is, for any given LREmore » system, strongly dependent on the oxygen partial pressure (PO{sub 2}) providing a new means by which to control the microstructure in the RE123 system.« less

Consideration of some dilute-solution phenomena based on an expression for the Gibbs free energy

NASA Astrophysics Data System (ADS)

Jonah, D. A.

1986-07-01

Rigorous expressions based on the Lennard-Jones (6 12) potential, are presented for the Gibbs and Helmholtz free energy of a dilute mixture. These expressions give the free energy of the mixture in terms of the thermodynamic properties of the pure solvent, thereby providing a convenient means of correlating dilute mixture behavior with that of the pure solvent. Expressions for the following dilute binary solution properties are derived: Henry's constant, limiting activity coefficients with their derivatives, solid solubilities in supercritical gases, and mixed second virial coefficients. The Henry's constant expression suggests a linear temperature dependence; application to solubility data for various gases in methane and water shows a good agreement between theory and experiment. In the thermodynamic modeling of supercritical fluid extraction, we have demonstrated how to predict new solubility-pressure isotherms from a given isotherm, with encouraging results. The mixed second virial coefficient expression has also been applied to experimental data; the agreement with theory is good.

Correlation of Solubility with the Metastable Limit of Nucleation Using Gauge-Cell Monte Carlo Simulations.

PubMed

Clark, Michael D; Morris, Kenneth R; Tomassone, Maria Silvina

2017-09-12

We present a novel simulation-based investigation of the nucleation of nanodroplets from solution and from vapor. Nucleation is difficult to measure or model accurately, and predicting when nucleation should occur remains an open problem. Of specific interest is the "metastable limit", the observed concentration at which nucleation occurs spontaneously, which cannot currently be estimated a priori. To investigate the nucleation process, we employ gauge-cell Monte Carlo simulations to target spontaneous nucleation and measure thermodynamic properties of the system at nucleation. Our results reveal a widespread correlation over 5 orders of magnitude of solubilities, in which the metastable limit depends exclusively on solubility and the number density of generated nuclei. This three-way correlation is independent of other parameters, including intermolecular interactions, temperature, molecular structure, system composition, and the structure of the formed nuclei. Our results have great potential to further the prediction of nucleation events using easily measurable solute properties alone and to open new doors for further investigation.

An isopiestic study of aqueous NaBr and KBr at 50 °C: Chemical equilibrium model of solution behavior and solubility in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems to high concentration and temperature

NASA Astrophysics Data System (ADS)

Christov, Christomir

2007-07-01

The isopiestic method has been used to determine the osmotic coefficients of the binary solutions NaBr-H 2O (from 0.745 to 5.953 mol kg -1) and KBr-H 2O (from 0.741 to 5.683 mol kg -1) at the temperature t = 50 °C. Sodium chloride solutions have been used as isopiestic reference standards. The isopiestic results obtained have been combined with all other experimental thermodynamic quantities available in literature (osmotic coefficients, water activities, bromide mineral's solubilities) to construct a chemical model that calculates solute and solvent activities and solid-liquid equilibria in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems from dilute to high solution concentration within the 0-300 °C temperature range. The Harvie and Weare [Harvie C., and Weare J. (1980) The prediction of mineral solubilities in naturalwaters: the Na-K-Mg-Ca-Cl-SO 4-H 2O system from zero to high concentration at 25 °C. Geochim. Cosmochim. Acta44, 981-997] solubility modeling approach, incorporating their implementation of the concentration-dependent specific interaction equations of Pitzer [Pitzer K. (1973) Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem.77, 268-277] is employed. The model for binary systems is validated by comparing activity coefficient predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solutions model due to data insufficiencies are discussed. This model expands the variable temperature sodium-potassium model of Greenberg and Moller [Greenberg J., and Moller N. (1989) The prediction of mineral solubilities in natural waters: a chemical equilibrium model for the Na-K-Ca-Cl-SO 4-H 2O system to high concentration from 0 to 250 °C. Geochim. Cosmochim. Acta53, 2503-2518] by evaluating Br - pure electrolyte and mixing solution parameters and the chemical potentials of three bromide solid phases: NaBr-2H 2O (cr), NaBr (cr) and KBr (cr).

A New Method of Constructing a Drug-Polymer Temperature-Composition Phase Diagram Using Hot-Melt Extrusion.

PubMed

Tian, Yiwei; Jones, David S; Donnelly, Conor; Brannigan, Timothy; Li, Shu; Andrews, Gavin P

2018-04-02

Current experimental methodologies used to determine the thermodynamic solubility of an API within a polymer typically involves establishing the dissolution/melting end point of the crystalline API within a physical mixture or through the use of the glass transition temperature measurement of a demixed amorphous solid dispersion. The measurable "equilibrium" points for solubility are normally well above the glass transition temperature of the system, meaning extrapolation is required to predict the drug solubility at pharmaceutically relevant temperatures. In this manuscript, we argue that the presence of highly viscous polymers in these systems results in experimental data that exhibits an under or overestimated value relative to the true thermodynamic solubility. In previous work, we demonstrated the effects of experimental conditions and their impact on measured and predicted thermodynamic solubility points. In light of current understanding, we have developed a new method to limit error associated with viscosity effects for application in small-scale hot-melt extrusion (HME). In this study, HME was used to generate an intermediate (multiphase) system containing crystalline drug, amorphous drug/polymer-rich regions as well as drug that was molecularly dispersed in polymer. An extended annealing method was used together with high-speed differential scanning calorimetry to accurately determine the upper and lower boundaries of the thermodynamic solubility of a model drug-polymer system (felodipine and Soluplus). Compared to our previously published data, the current results confirmed our hypothesis that the prediction of the liquid-solid curve using dynamic determination of dissolution/melting end point of the crystalline API physical mixture presents an underestimation relative to the thermodynamic solubility point. With this proposed method, we were able to experimentally measure the upper and lower boundaries of the liquid-solid curve for the model system. The relationship between inverse temperature and drug-polymer solubility parameter (χ) remained linear at lower drug loadings. Significantly higher solubility and miscibility between the felodipine-Soluplus system were derived from the new χ values.

The effect of polymer composition on the gelation behavior of PLGA-g-PEG biodegradable thermoreversible gels.

PubMed

Tarasevich, B J; Gutowska, A; Li, X S; Jeong, B-M

2009-04-01

Graft copolymers consisting of a poly(D,L-lactic acid-co-glycolic acid) backbone grafted with polyethylene glycol side chains were synthesized and formed thermoreversible gels in aqueous solutions that exhibited solution behavior at low temperature and sol-to-gel transitions at higher temperature. The composition of the polymer and relative amounts of polylactic acid, glycolic acid, and ethylene glycol were varied by controlling the precursor concentrations and reaction temperature. The gelation temperature could be systematically tailored from 15 to 34 degrees C by increasing the concentration of polyethylene glycol in the graft copolymer. The gelation temperature also depended on the polymer molecular weight and concentration. This work has importance for the development of water soluble gels with tailored compositions and gelation temperatures for use in tissue engineering and as injectable depots for drug delivery. Copyright 2008 Wiley Periodicals, Inc.

Temperature and curing time affect composite sorption and solubility

PubMed Central

de CASTRO, Fabrício Luscino Alves; CAMPOS, Bruno Barbosa; BRUNO, Kely Firmino; REGES, Rogério Vieira

2013-01-01

Objective: This study evaluated the effect of temperature and curing time on composite sorption and solubility. Material and Methods: Seventy five specimens (8x2 mm) were prepared using a commercial composite resin (ICE, SDI). Three temperatures (10º C, 25º C and 60º C) and five curing times (5 s, 10 s, 20 s, 40 s and 60 s) were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1); B: 7 days after storage (M2); C: 7 days after storage plus 1 day of drying (M3). The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%). Results: The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p<0.05). At 60º C, the composite sorption showed an inverse relationship with the curing time (p<0.05). The composite cured for 5 s showed higher sorption for the 40 s or 60 s curing times when compared with all temperatures (p<0.05). Curing times of 20 s and 40 s showed similar sorption data for all temperatures (p>0.05). The 60º C composite temperature led to lower values of sorption for all curing times when compared with the 10º C temperature (p<0.05). The same results were found when comparing 10º C and 25º C (p<0.05), except that the 20 s and 40 s curing times behaved similarly (p>0.05). Solubility was similar at 40 s and 60 s for all temperatures (p>0.05), but was higher at 10º C than at 60º C for all curing times (p<0.05). When the composite was cured at 25º C, similar solubility values were found when comparing the 5 s and 10 s or 20 s and 40 s curing times (p>0.05). Conclusion: In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and curing times. PMID:23739853

Carbon dioxide in magmas and implications for hydrothermal systems

USGS Publications Warehouse

Lowenstern, J. B.

2001-01-01

This review focuses on the solubility, origin, abundance, and degassing of carbon dioxide (CO2) in magma-hydrothermal systems, with applications for those workers interested in intrusion-related deposits of gold and other metals. The solubility of CO2 increases with pressure and magma alkalinity. Its solubility is low relative to that of H2O, so that fluids exsolved deep in the crust tend to have high CO2/H2O compared with fluids evolved closer to the surface. Similarly, CO2/H2O will typically decrease during progressive decompression- or crystallization-induced degassing. The temperature dependence of solubility is a function of the speciation of CO2, which dissolves in molecular form in rhyolites (retrograde temperature solubility), but exists as dissolved carbonate groups in basalts (prograde). Magnesite and dolomite are stable under a relatively wide range of mantle conditions, but melt just above the solidus, thereby contributing CO2 to mantle magmas. Graphite, diamond, and a free CO2-bearing fluid may be the primary carbon-bearing phases in other mantle source regions. Growing evidence suggests that most CO2 is contributed to arc magmas via recycling of subducted oceanic crust and its overlying sediment blanket. Additional carbon can be added to magmas during magma-wallrock interactions in the crust. Studies of fluid and melt inclusions from intrusive and extrusive igneous rocks yield ample evidence that many magmas are vapor saturated as deep as the mid crust (10-15 km) and that CO2 is an appreciable part of the exsolved vapor. Such is the case in both basaltic and some silicic magmas. Under most conditions, the presence of a CO2-bearing vapor does not hinder, and in fact may promote, the ascent and eruption of the host magma. Carbonic fluids are poorly miscible with aqueous fluids, particularly at high temperature and low pressure, so that the presence of CO2 can induce immiscibility both within the magmatic volatile phase and in hydrothermal systems. Because some metals, including gold, can be more volatile in vapor phases than coexisting liquids, the presence of CO2 may indirectly aid the process of metallogenesis by inducing phase separation.

Poly(aspartic acid) with adjustable pH-dependent solubility.

PubMed

Németh, Csaba; Gyarmati, Benjámin; Abdullin, Timur; László, Krisztina; Szilágyi, András

2017-02-01

Poly(aspartic acid) (PASP) derivatives with adjustable pH-dependent solubility were synthesized and characterized to establish the relationship between their structure and solubility in order to predict their applicability as a basic material for enteric coatings. Polysuccinimide, the precursor of PASP, was modified with short chain alkylamines, and the residual succinimide rings were subsequently opened to prepare the corresponding PASP derivatives. Study of the effect of the type and concentration of the side groups on the pH-dependent solubility of PASP showed that solubility can be adjusted by proper selection of the chemical structure. The Henderson-Hasselbalch (HH) and the extended HH equations were used to describe the pH-dependent solubility of the polymers quantitatively. The estimate provided by the HH equation is poor, but an accurate description of the pH-dependent solubility can be found with the extended HH equation. The dissolution rate of a polymer film prepared from a selected PASP derivative was determined by fluorescence marking. The film dissolved rapidly when the pH was increased above its pK a . Cellular viability tests show that PASP derivatives are non-toxic to a human cell line. These polymers are thus of great interest as starting materials for enteric coatings. Poly(amino acid) type biocompatible polymers were synthesized for future use as pharmaceutical film coatings. To this end, we tailored the pH-dependent solubility of poly(aspartic acid) (PASP). It was found that both the solubility and the pK a values of the modified PASP depended strongly on composition. Fluorescent marking was used to characterize the dissolution of a chosen PASP derivative. In acidic media only a negligible amount of the polymer dissolved, but dissolution was very fast and complete at the pH values that prevail in the small intestine. As a consequence, enteric coatings based on such PASP derivatives may be used for drug delivery in the gastrointestinal tract. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Measurement and modeling of CO₂ solubility in natural and synthetic formation brines for CO₂ sequestration.

PubMed

Zhao, Haining; Dilmore, Robert; Allen, Douglas E; Hedges, Sheila W; Soong, Yee; Lvov, Serguei N

2015-02-03

CO2 solubility data in the natural formation brine, synthetic formation brine, and synthetic NaCl+CaCl2 brine were collected at the pressures from 100 to 200 bar, temperatures from 323 to 423 K. Experimental results demonstrate that the CO2 solubility in the synthetic formation brines can be reliably represented by that in the synthetic NaCl+CaCl2 brines. We extended our previously developed model (PSUCO2) to calculate CO2 solubility in aqueous mixed-salt solution by using the additivity rule of the Setschenow coefficients of the individual ions (Na(+), Ca(2+), Mg(2+), K(+), Cl(-), and SO4(2-)). Comparisons with previously published models against the experimental data reveal a clear improvement of the proposed PSUCO2 model. Additionally, the path of the maximum gradient of the CO2 solubility contours divides the P-T diagram into two distinct regions: in Region I, the CO2 solubility in the aqueous phase decreases monotonically in response to increased temperature; in region II, the behavior of the CO2 solubility is the opposite of that in Region I as the temperature increases.

Effects of solvent density on retention in gas-liquid chromatography. I. Alkanes solutes in polyethylene glycol stationary phases.

PubMed

González, F R; Pérez-Parajón, J; García-Domínguez, J A

2002-04-12

Gas-liquid chromatographic columns were prepared coating silica capillaries with poly(oxyethylene) polymers of different molecular mass distributions, in the range of low number-average molar masses, where the density still varies significantly. A novel, high-temperature, rapid evaporation method was developed and applied to the static coating of the low-molecular-mass stationary phases. The analysis of alkanes retention data from these columns reveals that the dependence of the partition coefficient with the solvent macroscopic density is mainly due to a variation of entropy. Enthalpies of solute transfer contribute poorly to the observed variations of retention. Since the alkanes solubility diminishes with the increasing solvent density, and this variation is weakly dependent with temperature, it is concluded that the decrease of free-volume in the liquid is responsible for this behavior.

Solubility of alkali metal halides in the ionic liquid [C4C1im][OTf].

PubMed

Kuzmina, O; Bordes, E; Schmauck, J; Hunt, P A; Hallett, J P; Welton, T

2016-06-28

The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl, CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li(+), Na(+) and K(+) salts with anions matching the ionic liquid have also been investigated to determine how well these cations dissolve in [C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility of salts within this ionic liquid. The highest solubility found was for iodide salts, and the lowest solubility for the three fluoride salts. There is no outstanding difference in the solubility of salts with matching anions in comparison to halide salts. The experimental data were correlated employing several phase equilibria models, including ideal mixtures, van't Hoff, the λh (Buchowski) equation, the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that the van't Hoff model gave the best correlation results. On the basis of the experimental data the thermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systems together with computed gas phase metathesis parameters. Dissolution depends on the energy difference between enthalpies of fusion and dissolution of the solute salt. This demonstrates that overcoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionic liquids.

Effect of confinement in nano-porous materials on the solubility of a supercritical gas

NASA Astrophysics Data System (ADS)

Hu, Yaofeng; Huang, Liangliang; Zhao, Shuangliang; Liu, Honglai; Gubbins, Keith E.

2016-11-01

By combining Gibbs Ensemble Monte Carlo simulations and density functional theory, we investigate the influence of confinement in a slit-shaped carbon pore on the solubility of a supercritical solute gas in a liquid solvent. In the cases studied here, competing adsorption of the solvent and solute determines whether the solubility is enhanced or suppressed for larger pores. We find that the solubility in the confined system is strongly dependent on pore width, and that molecular packing effects are important for small pore widths. In addition, the solubility decreases on increase in the temperature, as for the bulk mixture, but the rate of decrease is greater in the pore due to a decrease in the partial molar enthalpy of the solute in the pore; this effect becomes greater as pore width is decreased. The solubility is increased on increasing the bulk pressure of the gas in equilibrium with the pore, and obeys Henry's law at lower pressures. However, the Henry constant differs significantly from that for the bulk mixture, and the range of pressure over which Henry's law applies is reduced relative to that for the bulk mixture. The latter observation indicates that solute-solute interactions become more important in the pore than for the bulk at a given bulk pressure. Finally, we note that different authors use different definitions of the solubility in pores, leading to some confusion over the reported phenomenon of 'oversolubility'. We recommend that solubility be defined as the overall mole fraction of solute in the pores, since it takes into account the increase in density of the solvent in the pores, and avoids ambiguity in the definition of the pore volume.

Heat transfer from Atlantic waters to sea ice in the Arctic Ocean: Evidence from dissolved argon

NASA Astrophysics Data System (ADS)

Moore, R. M.; Spitzer, W.

1990-11-01

In an attempt to determine whether the temperature and salinity properties of Arctic Ocean waters above the Atlantic water temperature maximum are the result of heat transfer to sea-ice, dissolved Ar has been measured as a temperature tracer. Consistent with such a hypothesis, it is found that there is a transition from supersaturation of Ar in the upper waters to undersaturation below a depth of 275m. Using the known dependence of the solubility of Ar on T and S, and assuming that the water was originally equilibrated with the atmosphere at 760mm Hg, it has been calculated that ca. 0.6° C of cooling can be attributed to transfer of heat to sea-ice.

Passive asymmetric transport of hesperetin across isolated rabbit cornea.

PubMed

Srirangam, Ramesh; Majumdar, Soumyajit

2010-07-15

Hesperetin, an aglycone of the flavanone hesperidin, is a potential candidate for the treatment of diabetic retinopathy and macular edema. The purpose of this investigation was to determine solubility, stability and in vitro permeability characteristics of hesperetin across excised rabbit corneas. Aqueous and pH dependent solubility was determined using standard shake flask method. Solution stability was evaluated as a function of pH (1.2-9) and temperature (25 and 40 degrees C). Permeability of hesperetin was determined across the isolated rabbit cornea utilizing a side-bi-side diffusion apparatus, in the apical to basolateral (A-B) and basolateral to apical (B-A) directions. Hesperetin displayed asymmetrical transcorneal transport with a 2.3-fold higher apparent permeability in the B-A direction compared to the A-B direction. The transport process was observed to be pH dependent. Surprisingly, however, the involvement of efflux transporters or proton-coupled carrier-systems was not evident in this asymmetric transcorneal diffusion process. The passive and pH dependent corneal transport of hesperetin could probably be attributable to corneal ultrastructure, physicochemical characteristics of hesperetin and the role of transport buffer components. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Conduction mechanism, impedance spectroscopic investigation and dielectric behavior of La0.5Ca0.5-xAgxMnO3 manganites with compositions below the concentration limit of silver solubility in perovskites (0 ≤ x ≤ 0.2).

PubMed

Rahmouni, H; Smari, M; Cherif, B; Dhahri, E; Khirouni, K

2015-06-14

This study presents the electrical properties, complex impedance analysis and dielectrical behavior of La0.5Ca0.5-xAgxMnO3 manganites with compositions below the concentration limit of silver solubility in perovskites (0 ≤ x ≤ 0.2). Transport measurements indicate that all the samples have a semiconductor-like behavior. The metal-semiconductor transition is not observed across the whole temperature range explored [80 K-700 K]. At a specific temperature, a saturation region was marked in the σ (T) curves. We obtained a maximum σdc value at ambient temperature with the introduction of 20% Ag content. Two hopping models were applied to study the conduction mechanism. We found that activation energy (Ea) related to ac-conductivity is lower than the Ea implicated in dc-conductivity. Complex impedance analysis confirms the contribution of grain boundary to conductivity and permits the attribution of grain boundary capacitance evolution to the temperature dependence of the barrier layer width. From the temperature dependence of the average normalized change (ANC), we deduce the temperature at which the available density of trapped charge states vanishes. Such a temperature is close to the temperature at which the saturation region appears in σ(T) curves. Moreover, complex impedance analysis (CIA) indicates the presence of electrical relaxation in materials. It is noteworthy that relaxation species such as defects may be responsible for electrical conduction. The dielectric behavior of La0.5Ca0.5-xAgxMnO3 manganites has a Debye-like relaxation with a sharp decrease in the real part of permittivity at a frequency where the imaginary part of permittivity (ε'') and tg δ plots versus frequency demonstrate a relaxation peak. The Debye-like relaxation is explained by Maxwell-Wagner (MW) polarization. Experimental results are found to be in good agreement with the Smit and Wijn theory.

Heat capacity, resistivity, and angular dependent magnetization studies of single crystal Nd 1 + ϵ Fe 4 B 4 for ϵ ≈ 1 7

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

Conner, Benjamin S.; Susner, Michael A.; UES Inc., Beavercreek, OH

Advances in crystal growth have allowed for synthesis of large single crystals of Nd 1+ϵFe 4B 4, a well-known phase with a modulated structure. As a result we are able to report heat capacity and resistivity measurements on a single crystal Nd 1+ϵFe 4B 4 sample with a distribution of ϵ that skews towards the solubility limit of Nd near ϵ ≈ 17. Heat capacity measurements show evidence of crystal field splitting at temperatures higher than the long-range ferromagnetic Curie temperature. Heat capacity, resistivity, and magnetization measurements all confirm a Curie temperature of 7 K which is lower than previouslymore » reported values in the Nd 1+ϵFe 4B 4 system. Here, we also perform measurements of the angular dependence of the magnetization and discover behavior associated with the magnetic anisotropy that is inconsistent with the simple description previously proposed.« less

Heat capacity, resistivity, and angular dependent magnetization studies of single crystal Nd 1 + ϵ Fe 4 B 4 for ϵ ≈ 1 7

DOE PAGES

Conner, Benjamin S.; Susner, Michael A.; UES Inc., Beavercreek, OH; ...

2017-04-04

Advances in crystal growth have allowed for synthesis of large single crystals of Nd 1+ϵFe 4B 4, a well-known phase with a modulated structure. As a result we are able to report heat capacity and resistivity measurements on a single crystal Nd 1+ϵFe 4B 4 sample with a distribution of ϵ that skews towards the solubility limit of Nd near ϵ ≈ 17. Heat capacity measurements show evidence of crystal field splitting at temperatures higher than the long-range ferromagnetic Curie temperature. Heat capacity, resistivity, and magnetization measurements all confirm a Curie temperature of 7 K which is lower than previouslymore » reported values in the Nd 1+ϵFe 4B 4 system. Here, we also perform measurements of the angular dependence of the magnetization and discover behavior associated with the magnetic anisotropy that is inconsistent with the simple description previously proposed.« less

Coupled phase and aqueous species equilibrium of the H 2O-CO 2-NaCl-CaCO 3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite

NASA Astrophysics Data System (ADS)

Duan, Zhenhao; Li, Dedong

2008-10-01

A model is developed for the calculation of coupled phase and aqueous species equilibrium in the H 2O-CO 2-NaCl-CaCO 3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite. The vapor-liquid-solid (calcite, halite) equilibrium together with the chemical equilibrium of H +, Na +, Ca 2+, CaHCO3+, Ca(OH) +, OH -, Cl -, HCO3-, CO32-, CO 2(aq) and CaCO 3(aq) in the aqueous liquid phase as a function of temperature, pressure, NaCl concentrations, CO 2(aq) concentrations can be calculated, with accuracy close to those of experiments in the stated T- P- m range, hence calcite solubility, CO 2 gas solubility, alkalinity and pH values can be accurately calculated. The merit and advantage of this model is its predictability, the model was generally not constructed by fitting experimental data. One of the focuses of this study is to predict calcite solubility, with accuracy consistent with the works in previous experimental studies. The resulted model reproduces the following: (1) as temperature increases, the calcite solubility decreases. For example, when temperature increases from 273 to 373 K, calcite solubility decreases by about 50%; (2) with the increase of pressure, calcite solubility increases. For example, at 373 K changing pressure from 10 to 500 bar may increase calcite solubility by as much as 30%; (3) dissolved CO 2 can increase calcite solubility substantially; (4) increasing concentration of NaCl up to 2 m will increase calcite solubility, but further increasing NaCl solubility beyond 2 m will decrease its solubility. The functionality of pH value, alkalinity, CO 2 gas solubility, and the concentrations of many aqueous species with temperature, pressure and NaCl (aq) concentrations can be found from the application of this model. Online calculation is made available on www.geochem-model.org/models/h2o_co2_nacl_caco3/calc.php.

Study on the Equilibrium Between Liquid Iron and Calcium Vapor

NASA Astrophysics Data System (ADS)

Berg, Martin; Lee, Jaewoo; Sichen, Du

2017-06-01

The solubility of calcium in liquid iron at 1823 K and 1873 K (1550 °C and 1600 °C) as a function of calcium potential was studied experimentally. The measurements were performed using a closed molybdenum holder in which liquid calcium and liquid iron were held at different temperatures. The results indicate a linear relationship between the activity of calcium, relative to pure liquid calcium, and the mole fraction of dissolved calcium in liquid iron, with a negligible temperature dependency in the ranges studied. The activity coefficient of calcium in liquid iron at infinite dilution, γ_{Ca(l0°, was calculated as 1551.

Overheated and Out of Breath: Temperature Regulation of Respiration and Oxygen Supply in Coastal Zooplankton

NASA Astrophysics Data System (ADS)

Roman, M.; Elliott, D. T.; Pierson, J. J.

2016-02-01

Increasing global coastal hypoxia occurs under a large range of temperature and salinity conditions. Temperature directly influences oxygen solubility in seawater as well as the oxygen demand of zooplankton, thus oxygen concentration alone is not sufficient to categorize the biological impact of hypoxia for pelagic organisms. To effectively assess the impacts of hypoxic stress on zooplankton habitat space and production, it is necessary to consider the effects of temperature on both oxygen availability and zooplankton metabolism. Our analysis and modeling evaluate available oxygen (partial pressure and concentration) in the context of ambient temperature conditions and zooplankton oxygen demand. We will present allometric models, accounting for both body size and temperature that predict temperature-dependent oxygen supply and demand in coastal zooplankton. Our goal is to develop generalized, functional relationships that describe and quantify the interactive effects of temperature and low oxygen on coastal zooplankton that can lead to improved size-structured models that serve to predict impacts of increasing coastal hypoxia on pelagic food webs.

Dissolution thermodynamics and solubility of silymarin in PEG 400-water mixtures at different temperatures.

PubMed

Shakeel, Faiyaz; Anwer, Md Khalid

2015-01-01

An isothermal method was used to measure the solubility of silymarin in binary polyethylene glycol 400 (PEG 400) + water co-solvent mixtures at temperatures T = 298.15-333.15 K and pressure p = 0.1 MPa. Apelblat and Yalkowsky models were used to correlate experimental solubility data. The mole fraction solubility of silymarin was found to increase with increasing the temperature and mass fraction of PEG 400 in co-solvent mixtures. The root mean square deviations were observed in the range of 0.48-5.32% and 1.50-9.65% for the Apelblat equation and Yalkowsky model, respectively. The highest and lowest mole fraction solubility of silymarin was observed in pure PEG 400 (0.243 at 298.15 K) and water (1.46 × 10(-5) at 298.15 K). Finally, thermodynamic parameters were determined by Van't Hoff and Krug analysis, which indicated an endothermic and spontaneous dissolution of silymarin in all co-solvent mixtures.

Heat-induced formation of myosin oligomer-soluble filament complex in high-salt solution.

PubMed

Shimada, Masato; Takai, Eisuke; Ejima, Daisuke; Arakawa, Tsutomu; Shiraki, Kentaro

2015-02-01

Heat-induced aggregation of myosin into an elastic gel plays an important role in the water-holding capacity and texture of meat products. Here, we investigated thermal aggregation of porcine myosin in high-salt solution over a wide temperature range by dynamic light scattering experiments. The myosin samples were readily dissolved in 1.0 M NaCl at 25 °C followed by dilution into various salt concentrations. The diluted solutions consistently contained both myosin monomers and soluble filaments. The filament size decreased with increasing salt concentration and temperature. High temperatures above Tm led to at least partial dissociation of soluble filaments and thermal unfolding, resulting in the formation of soluble oligomers and binding to the persistently present soluble filaments. Such a complex formation between the oligomers and filaments has never been observed. Our results provide new insight into the heat-induced myosin gelation in high-salt solution. Copyright © 2014 Elsevier B.V. All rights reserved.

Can hydrothermal pretreatment improve anaerobic digestion for biogas from lignocellulosic biomass?

PubMed

Wang, Dou; Shen, Fei; Yang, Gang; Zhang, Yanzong; Deng, Shihuai; Zhang, Jing; Zeng, Yongmei; Luo, Tao; Mei, Zili

2018-02-01

Hydrothermally-pretreated rice straw (HPRS) from various pretreatment temperatures was anaerobically-digested in whole slurry. Results indicated promoting pretreatment temperature significantly deconstructed rice straw, and facilitated the conversion of insoluble fractions to soluble fractions. Although 306.6 mL/g TS biogas was maximally yielded in HPRS-90 and HPRS-180, respectively, via digestion in whole slurry, it was only 3% promotion compared to the unpretreated rice straw. HPRS-210 yielded 208.5 mL/g TS biogas, which was 30% reduction with longer lag period of 19.8 d, suggesting serious inhibitions happened. Through slightly increasing organic loading, more serious acidification and reduction on biogas yield, especially at higher pretreatment temperatures, indicated the soluble fractions controlled digestion performances. Pearson correlation analysis suggested negative relationship existed between methane yield and the soluble fractions including soluble carbohydrates, formic acid and furfural. Hydrothermal pretreatment, especially at higher temperature, did not improve anaerobic digestion, thereby, was not recommended, however, lower temperature can be considered potentially. Copyright © 2017 Elsevier Ltd. All rights reserved.

Model evaluation of temperature dependency for carbon and nitrogen removal in a full-scale activated sludge plant treating leather-tanning wastewater.

PubMed

Görgün, Erdem; Insel, Güçlü; Artan, Nazik; Orhon, Derin

2007-05-01

Organic carbon and nitrogen removal performance of a full-scale activated sludge plant treating pre-settled leather tanning wastewater was evaluated under dynamic process temperatures. Emphasis was placed upon observed nitrogen removal depicting a highly variable magnitude with changing process temperatures. As the plant was not specifically designed for this purpose, observed nitrogen removal could be largely attributed to simultaneous nitrification and denitrification presumably occurring at increased process temperatures (T>25 degrees C) and resulting low dissolved oxygen levels (DO<0.5 mgO2/L). Model evaluation using long-term data revealed that the yearly performance of activated sludge reactor could be successfully calibrated by means of temperature dependent parameters associated with nitrification, hydrolysis, ammonification and endogenous decay parameters. In this context, the Arrhenius coefficients of (i) for the maximum autotrophic growth rate, [image omitted]A, (ii) maximum hydrolysis rate, khs and (iii) endogenous heterotrophic decay rate, bH were found to be 1.045, 1.070 and 1.035, respectively. The ammonification rate (ka) defining the degradation of soluble organic nitrogen could not be characterized however via an Arrhenius-type equation.

Measurement of hydrogen solubility and desorption rate in V-4Cr-4Ti and liquid lithium-calcium alloys

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

Park, J.H.; Erck, R.; Park, E.T.

1997-04-01

Hydrogen solubility in V-4Cr-4Ti and liquid lithium-calcium was measured at a hydrogen pressure of 9.09 x 10{sup {minus}4} torr at temperatures between 250 and 700{degrees}C. Hydrogen solubility in V-4Cr-4Ti and liquid lithium decreased with temperature. The measured desorption rate of hydrogen in V-4Cr-4Ti is a thermally activated process; the activation energy is 0.067 eV. Oxygen-charged V-4Cr-4Ti specimens were also investigated to determine the effect of oxygen impurity on hydrogen solubility and desorption in the alloy. Oxygen in V-4Cr-4Ti increases hydrogen solubility and desorption kinetics. To determine the effect of a calcium oxide insulator coating on V-4Cr-4Ti, hydrogen solubility in lithium-calciummore » alloys that contained 0-8.0 percent calcium was also measured. The distribution ratio R of hydrogen between liquid lithium or lithium-calcium and V-4Cr-4Ti increased as temperature decreased (R {approx} 10 and 100 at 700 and 250{degrees}C, respectively). However at <267{degrees}C, solubility data could not be obtained by this method because of the slow kinetics of hydrogen permeation through the vanadium alloy.« less

Le Chatelier's Principle and the Prediction Temperature on Solubilities.

ERIC Educational Resources Information Center

Fernandez-Prini, R.

1982-01-01

Discusses Le Chatelier's Principle from a thermodynamic perspective and applies it to the effect of temperature on the solubility of gases in liquids. Rationale of this discussion is to evaluate data in a previous article claimed to be contradictory to the Principle. (Author/JN)

Urban enhancement of PM10 bioaerosol tracers relative to background locations in the Midwestern United States

NASA Astrophysics Data System (ADS)

Rathnayake, Chathurika M.; Metwali, Nervana; Baker, Zach; Jayarathne, Thilina; Kostle, Pamela A.; Thorne, Peter S.; O'Shaughnessy, Patrick T.; Stone, Elizabeth A.

2016-05-01

Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and copollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM10) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012. Endotoxins from Gram-negative bacteria (and a few Gram-positive bacteria), water-soluble proteins, and tracers for fungal spores (fungal glucans, arabitol, and mannitol) were ubiquitous and showed significant seasonal variation and dependence on temperature. Fungal spores were elevated in spring and peaked in summer, following the seasonal growing cycle, while endotoxins peaked in autumn during the row crop harvesting season. Paired comparisons of bioaerosols in urban and background sites revealed significant urban enhancements in PM10, fungal glucans, endotoxins, and water-soluble proteins relative to background locations, such that urban populations have a greater outdoor exposure to bioaerosols. These bioaerosols contribute, in part, to the urban excesses in PM10. Higher bioaerosol mass fractions in urban areas relative to background sites indicate that urban areas serve as a source of bioaerosols. Similar urban enhancements in water-soluble calcium and its correlation with bioaerosol tracers point toward windblown soil as an important source of bioaerosols in urban areas.

Development of High Temperature Type Vacuum Insulation Panel using Soluble Polyimide and Characteristic Evaluation

NASA Astrophysics Data System (ADS)

Araki, Kuninari; Kamoto, Daigorou; Matsuoka, Shin-Ichi

The utilization is expected from the high-insulated characteristic as a tool for energy saving also in the high temperature insulation fields as in vacuum insulation panels (VIP) in the future. For high temperature, the material composition and process of VIP were reviewed, the SUS foil was adopted as packaging material, and soluble polyimide was developed as the thermo compression bonding material for high temperature VIP at 150°C. To lower the glass-transition temperature (Tg) under 200°C, we elaborated the new soluble polyimide using aliphatic diamine copolymer, and controlled Tg to about 176°C. By making from trial VIP and evaluations, it was possible to be maintain high performance concerning the coefficient of thermal conductivity [λ<0.008 W/(m·K) at 150°C].

Solubility of polyvalent cations in fogwater at an urban site in Strasbourg (France)

NASA Astrophysics Data System (ADS)

Millet, M.; Wortham, H.; Mirabel, Ph.

The concentrations in the soluble and total (soluble + insoluble) fractions of Mg, Ca, Fe, Mn, Zn, Al, Cd and Pb have been analysed by "inductively coupled plasma (ICP)" in 14 fog events collected in 1992 at an urban site in France (Strasbourg). For each fog event, two droplet size categories (2-6 μm and 5-8 μm) have been collected separately. For the analysis of the polyvalent cations in the soluble and total fractions, an analytical procedure using ICP and filtration on cellulose/PVC filters has been developed. The study of the solubility of some polyvalent cations has shown that two of the most important factors controlling the partitioning between the soluble and insoluble fraction are the nature of the particles and the pH of the fogwater. The influence of pH depended on the element. The solubility of Pb, Cd, Al, Fe, Mg, and Ca were pH dependent whereas, Zn and Mn solubility varied but no relationship with pH existed, ranging between 25 and 100% and 10 and 100%, respectively. On the other hand, Mg, Pb and Ca were predominantly present in the soluble phase, whereas Al was prevalent in the insoluble fraction. In the case of Cd and Fe., the presence in the soluble or insoluble phase depended largely on the fogwater pH.

Modeling solubility of CO2/hydrocarbon gas in ionic liquid ([emim][FAP]) using Aspen Plus simulations.

PubMed

Bagchi, Bishwadeep; Sati, Sushmita; Shilapuram, Vidyasagar

2017-08-01

The Peng-Robinson equation of state with quadratic van der Waals (vdW) mixing rule model was chosen to perform the thermodynamic calculations in Flash3 column of Aspen Plus to predict the solubility of CO 2 or any one of the hydrocarbons (HCs) among methane, ethane, propane, and butane in an ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([emim][FAP]). Bubble point pressure, solubility, bubble point temperature, fugacity, and partial molar volume at infinite dilution were obtained from the simulations, and enthalpy of absorption, Gibbs free energy of solvation, and entropy change of absorption were estimated by thermodynamic relations. Results show that carbon chain length has a significant effect on the bubble point pressure. Methane has the highest bubble point pressure among all the considered HCs and CO 2 . The bubble point pressure and fugacity variation with temperature is different for CO 2 as compared to HCs for mole fractions above 0.2. Two different profiles are noticed for enthalpy of absorption when plotted as a function of mole fraction of gas soluble in IL. Partial molar volume of CO 2 decreases with increase in temperature in [emim][FAP], while it is increased for HCs. Bubble point temperature decreases with increase in the mole fraction of the solute. Entropy of solvation increases with temperature till a particular value followed by a decrease with further increase in temperature. Gibbs free energy change of solvation showed that the process of solubility was spontaneous.

Structural Characterization of Apomyoglobin Self-Associated Species in Aqueous Buffer and Urea Solution

PubMed Central

Chow, Charles; Kurt, Neşe; Murphy, Regina M.; Cavagnero, Silvia

2006-01-01

The biophysical characterization of nonfunctional protein aggregates at physiologically relevant temperatures is much needed to gain deeper insights into the kinetic and thermodynamic relationships between protein folding and misfolding. Dynamic and static laser light scattering have been employed for the detection and detailed characterization of apomyoglobin (apoMb) soluble aggregates populated at room temperature upon dissolving the purified protein in buffer at pH 6.0, both in the presence and absence of high concentrations of urea. Unlike the β-sheet self-associated aggregates previously reported for this protein at high temperatures, the soluble aggregates detected here have either α-helical or random coil secondary structure, depending on solvent and solution conditions. Hydrodynamic diameters range from 80 to 130 nm, with semiflexible chain-like morphology. The combined use of low pH and high urea concentration leads to structural unfolding and complete elimination of the large aggregates. Even upon starting from this virtually monomeric unfolded state, however, protein refolding leads to the formation of severely self-associated species with native-like secondary structure. Under these conditions, kinetic apoMb refolding proceeds via two parallel routes: one leading to native monomer, and the other leading to a misfolded and heavily self-associated state bearing native-like secondary structure. PMID:16214860

Tunable thermoresponsive pyrrolidone-based polymers from pyroglutamic acid, a bio-derived resource.

PubMed

Bhat, Rajani; Pietrangelo, Agostino

2013-03-12

A series of pyrrolidone-based polymers is prepared from pyroglutamic acid, a bio-derived resource. Polymers bearing simple alkoxy substituents (e.g., methoxy, ethoxy, and butoxy) are soluble in common organic solvents and possess glass transition temperatures that are dependent on the length of the alkoxy residue. Replacing these substituents with an ether moiety (CH3 OCH2 CH2 O-) affords a highly sensitive and reversible thermoresponsive polymer with a lower critical solution temperature (LCST) of 42 °C in water. Copolymers composed of repeat units bearing both the ether and simple alkoxy residues are found to exhibit LCSTs that are highly dependent on the nature of the hydrophobic alkoxy residue suggesting that the LCSTs of these polymers can be successfully tuned by simply tailoring the copolymer structure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Seasonal cycle and temperature dependence of pinene oxidation products, dicarboxylic acids and nitrophenols in fine and coarse air particulate matter

NASA Astrophysics Data System (ADS)

Zhang, Y. Y.; Müller, L.; Winterhalter, R.; Moortgat, G. K.; Hoffmann, T.; Pöschl, U.

2010-08-01

Filter samples of fine and coarse air particulate matter (PM) collected over a period of one year in central Europe (Mainz, Germany) were analyzed for water-soluble organic compounds (WSOCs), including the α- and β-pinene oxidation products pinic acid, pinonic acid and 3-methyl-1,2,3-butanetricarboxylic acid (3-MBTCA), as well as a variety of dicarboxylic acids and nitrophenols. Seasonal variations and other characteristic features in fine, coarse, and total PM (TSP) are discussed with regard to aerosol sources and sinks in comparison to data from other studies and regions. The ratios of adipic acid and phthalic acid to azelaic acid indicate that the investigated aerosol samples were mainly influenced by biogenic sources. A strong Arrhenius-type correlation was found between the 3-MBTCA concentration and inverse temperature (R2 = 0.79, n = 52, Ea = 126 ± 10 kJ mol-1, temperature range 275-300 K). Model calculations suggest that the temperature dependence observed for 3-MBTCA can be explained by enhanced photochemical production due to an increase of hydroxyl radical (OH) concentration with increasing temperature, whereas the influence of gas-particle partitioning appears to play a minor role. The results indicate that the OH-initiated oxidation of pinonic acid is the rate-limiting step in the formation of 3-MBTCA, and that 3-MBTCA may be a suitable tracer for the chemical aging of biogenic secondary organic aerosol (SOA) by OH radicals. An Arrhenius-type temperature dependence was also observed for the concentration of pinic acid (R2 = 0.60, n = 56, Ea = 84 ± 9 kJ mol-1); it can be tentatively explained by the temperature dependence of biogenic pinene emission as the rate-limiting step of pinic acid formation.

Seasonal cycle and temperature dependence of pinene oxidation products, dicarboxylic acids and nitrophenols in fine and coarse air particulate matter

NASA Astrophysics Data System (ADS)

Zhang, Y.; Müller, L.; Winterhalter, R.; Moortgat, G. K.; Hoffmann, T.; Pöschl, U.

2010-05-01

Filter samples of fine and coarse air particulate matter (PM) collected over a period of one year in central Europe (Mainz, Germany) were analyzed for water-soluble organic compounds (WSOCs), including the α- and β-pinene oxidation products pinic acid, pinonic acid and 3-methyl-1,2,3-butanetricarboxylic acid (3-MBTCA), as well as a variety of dicarboxylic acids and nitrophenols. Seasonal variations and other characteristic features in fine, coarse, and total PM (TSP) are discussed with regard to aerosol sources and sinks in comparison to data from other studies and regions. The ratios of adipic acid and phthalic acid to azelaic acid indicate that the investigated samples were mainly influenced by biogenic sources. A strong Arrhenius-type correlation was found between the 3-MBTCA concentration and inverse temperature (R2=0.79, n=52, Ea=126±10 kJ mol-1, temperature range 275-300 K). Model calculations suggest that the temperature dependence observed for 3-MBTCA can be explained by enhanced photochemical production due to an increase of hydroxyl radical (OH) concentration with increasing temperature, whereas the influence of gas-particle partitioning appears to play a minor role. The results indicate that the OH-initiated oxidation of pinonic acid is the rate-limiting step in the formation of 3-MBTCA, and that 3-MBTCA may be a suitable tracer for the chemical aging of biogenic secondary organic aerosol (SOA) by OH radicals. An Arrhenius-type temperature dependence was also observed for the concentration of pinic acid (R2=0.60, n=56, Ea=84±9 kJ mol-1); it can be tentatively explained by the temperature dependence of biogenic pinene emission as the rate-limiting step of pinic acid formation.

Breadboard activities for advanced protein crystal growth

NASA Technical Reports Server (NTRS)

Rosenberger, Franz; Banish, Michael

1993-01-01

The proposed work entails the design, assembly, testing, and delivery of a turn-key system for the semi-automated determination of protein solubilities as a function of temperature. The system will utilize optical scintillation as a means of detecting and monitoring nucleation and crystallite growth during temperature lowering (or raising, with retrograde solubility systems). The deliverables of this contract are: (1) turn-key scintillation system for the semi-automatic determination of protein solubilities as a function of temperature, (2) instructions and software package for the operation of the scintillation system, and (3) one semi-annual and one final report including the test results obtained for ovostatin with the above scintillation system.

Assessing the Salting-Out Behavior of 2,4-Dinitrobenzaldehyde and 2,6-Dinitrobenzaldehyde from Solubility Values in Pure Water and Seawater at Temperatures between (280 and 313) K

DTIC Science & Technology

2011-05-12

Dinitrobenzaldehyde from Solubility Values in Pure Water and Seawater at Temperatures between (280 and 313) K Dianne J. Luning Prak* and Daniel W. O’Sullivan...1998, 37, 25–31. (7) O’Sullivan, D. W.; Denzel, J. R.; Luning Prak, D. J. Photolysis of 2,4-Dinitrotoluene and 2,6-Dinitrotoluene in Seawater. Aquat...Solubility of Aromatic Compounds.Chemosphere 1984, 13, 881–888. (13) Luning Prak, D. J.; O’Sullivan, D. W. Solubility of 2,4-Dini- trotoluene and 2,4,6

Short communication: Effect of storage temperature on the solubility of milk protein concentrate 80 (MPC80) treated with NaCl or KCl.

PubMed

Sikand, V; Tong, P S; Walker, J; Wang, T; Rodriguez-Saona, L E

2016-03-01

A previous study in our laboratory showed that addition of 150 mM NaCl or KCl into diafiltration water improved the solubility of freshly made milk protein concentrate 80 (MPC80). In the present study, the objectives were (1) to evaluate the solubility of NaCl- or KCl-treated MPC80 samples kept at varying temperatures and then stored for extensive periods at room temperature (21 °C ± 1 °C); and (2) to determine if MPC80 samples stored at different temperatures and protein conformation can be grouped or categorized together. Freshly manufactured MPC80 samples were untreated (control), processed with NaCl, or processed with KCl. One set of sample bags was stored at 4 °C; second and third sets of bags were kept at 25 °C and 55 °C for 1 mo (31 d) and then transferred to room temperature (21 °C ± 1 °C) storage conditions for 1 yr (365 d). Samples were tested for nitrogen solubility index (NSI) and for protein changes by Fourier-transform infrared (FTIR) spectroscopy. Analysis of variance results for NSI showed 2 significantly different groupings of MPC80 samples. The more soluble group contained samples treated with NaCl or KCl and stored at either 4 °C or 25 °C. These samples had mean NSI >97.5%. The less soluble groups contained all control samples, regardless of storage temperature, and NaCl- or KCl-treated samples stored at 55 °C. These samples had mean NSI from 39.5 to 58%. Within each of these groups (more soluble and less soluble), no significant differences in solubility were detected. Pattern recognition analysis by soft independent modeling of class analogy (SIMCA) was used to assess protein changes during storage by monitoring the amide I and amide II (1,700(-1) to 1,300 cm(-1)) regions. Dominant bands were observed at 1,385 cm(-1) for control, 1,551 cm(-1) for KCl-treated samples, and 1,694 cm(-1) for NaCl-treated samples. Moreover, SIMCA clustered the MPC80 samples stored at 4 °C separately from samples stored at 25 °C and 55 °C. This study demonstrates that (1) the addition of NaCl or KCl during MPC80 manufacture reduces the deleterious changes in solubility upon prolonged storage at 4 °C or 25 °C, and (2) the solubility of samples stored at 55 °C is poor irrespective of salt treatment. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Modeling bronchial circulation with application to soluble gas exchange: description and sensitivity analysis.

PubMed

Bui, T D; Dabdub, D; George, S C

1998-06-01

The steady-state exchange of inert gases across an in situ canine trachea has recently been shown to be limited equally by diffusion and perfusion over a wide range (0.01-350) of blood solubilities (betablood; ml . ml-1 . atm-1). Hence, we hypothesize that the exchange of ethanol (betablood = 1,756 at 37 degrees C) in the airways depends on the blood flow rate from the bronchial circulation. To test this hypothesis, the dynamics of the bronchial circulation were incorporated into an existing model that describes the simultaneous exchange of heat, water, and a soluble gas in the airways. A detailed sensitivity analysis of key model parameters was performed by using the method of Latin hypercube sampling. The model accurately predicted a previously reported experimental exhalation profile of ethanol (R2 = 0.991) as well as the end-exhalation airstream temperature (34.6 degrees C). The model predicts that 27, 29, and 44% of exhaled ethanol in a single exhalation are derived from the tissues of the mucosa and submucosa, the bronchial circulation, and the tissue exterior to the submucosa (which would include the pulmonary circulation), respectively. Although the concentration of ethanol in the bronchial capillary decreased during inspiration, the three key model outputs (end-exhaled ethanol concentration, the slope of phase III, and end-exhaled temperature) were all statistically insensitive (P > 0.05) to the parameters describing the bronchial circulation. In contrast, the model outputs were all sensitive (P < 0.05) to the thickness of tissue separating the core body conditions from the bronchial smooth muscle. We conclude that both the bronchial circulation and the pulmonary circulation impact soluble gas exchange when the entire conducting airway tree is considered.

The effect of the cation alkyl chain branching on mutual solubilities with water and toxicities.

PubMed

Kurnia, Kiki A; Sintra, Tânia E; Neves, Catarina M S S; Shimizu, Karina; Canongia Lopes, José N; Gonçalves, Fernando; Ventura, Sónia P M; Freire, Mara G; Santos, Luís M N B F; Coutinho, João A P

2014-10-07

The design of ionic liquids has been focused on the cation-anion combinations but other more subtle approaches can be used. In this work the effect of the branching of the cation alkyl chain on the design of ionic liquids (ILs) is evaluated. The mutual solubilities with water and toxicities of a series of bis(trifluoromethylsulfonyl)-based ILs, combined with imidazolium, pyridinium, pyrrolidinium, and piperidinium cations with linear or branched alkyl chains, are reported. The mutual solubility measurements were carried out in the temperature range from (288.15 to 323.15) K. From the obtained experimental data, the thermodynamic properties of the solution (in the water-rich phase) were determined and discussed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used to predict the liquid-liquid equilibrium. Furthermore, molecular dynamic simulations were also carried out aiming to get a deeper understanding of these fluids at the molecular level. The results show that the increase in the number of atoms at the cation ring (from five to six) leads to a decrease in the mutual solubilities with water while increasing their toxicity, and as expected from the well-established relationship between toxicities and hydrophobicities of ILs. The branching of the alkyl chain was observed to decrease the water solubility in ILs, while increasing the ILs solubility in water. The inability of COSMO-RS to correctly predict the effect of branching alkyl chains toward water solubility on them was confirmed using molecular dynamic simulations to be due to the formation of nano-segregated structures of the ILs that are not taken into account by the COSMO-RS model. In addition, the impact of branched alkyl chains on the toxicity is shown to be not trivial and to depend on the aromatic nature of the ILs.

Trifunctional Epoxy Resin Composites Modified by Soluble Electrospun Veils: Effect on the Viscoelastic and Morphological Properties

PubMed Central

Ognibene, Giulia; Mannino, Salvatore

2018-01-01

Electrospun veils from copolyethersulfones (coPES) were prepared as soluble interlaminar veils for carbon fiber/epoxy composites. Neat, resin samples were impregnated into coPES veils with unmodified resin, while dry carbon fabrics were covered with electrospun veils and then infused with the unmodified epoxy resin to prepare reinforced laminates. The thermoplastic content varied from 10 wt% to 20 wt%. TGAP epoxy monomer showed improved and fast dissolution for all the temperatures tested. The unreinforced samples were cured first at 180 °C for 2 h and then were post-cured at 220 °C for 3 h. These sample showed a high dependence on the curing cycle. Carbon reinforced samples showed significant differences compared to the neat resin samples in terms of both viscoelastic and morphological properties. PMID:29522444

Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys

NASA Astrophysics Data System (ADS)

Maltsev, Dmitry S.; Volkovich, Vladimir A.; Yamshchikov, Leonid F.; Chukin, Andrey V.

2016-09-01

Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys were studied. Temperature dependences of gadolinium activity in the studied alloys were determined at 573-1073 K employing the EMF method. Solubility of gadolinium in the Ga-Sn and Ga-Zn alloys was measured at 462-1073 K using IMCs sedimentation method. Activity coefficients as well as partial and excess thermodynamic functions of gadolinium in the studied alloys were calculated on the basis of the obtained experimental data.

Methacrylate derivatives incorporating pyroglutamic acid.

PubMed

Smith, Tara J; Mathias, Lon J

2002-01-01

Methacrylates containing pyroglutamic acid were synthesized in good yields. Methyl alpha-pyroglutamyl methylacrylate (PyMM) and methyl alpha-pyroglutamidoundecanoyl methylacrylate (PyUM) give very fast photopolymerization rates both in homopolymerizations and with widely used commercial monomers N-vinyl pyrrolidinone (NVP) and hydroxyethyl methacrylate (HEMA). Soluble or cross-linked homopolymers can be obtained depending upon polymerization temperature. Pyroglutamic methacrylates polymerize without added initiator in the melt. Solution cast, photocured, and thermally cured coatings gave good to excellent adhesion to poly(ethylene terephthalate) and glass surfaces.

FNAS/advanced protein crystal growth

NASA Technical Reports Server (NTRS)

Rosenberger, Franz

1992-01-01

A scintillation method is presented for determination of the temperature dependence of the solubility, S(T), of proteins in 50-100 micro-l volumes of solution. S(T) data for lysozyme and horse serum albumin were obtained for various combinations of pH and precipitant concentrations. The resulting kinetics and equilibrium information was used for dynamic control, that is the separation of nucleation and growth stages in protein crystallization. Individual lysozyme and horse serum albumin crystals were grown in 15-20 micro-l solution volumes contained in x-ray capillaries.

Solubility and crystallization of xylose isomerase from Streptomyces rubiginosus

NASA Astrophysics Data System (ADS)

Vuolanto, Antti; Uotila, Sinikka; Leisola, Matti; Visuri, Kalevi

2003-10-01

We have studied the crystallization and crystal solubility of xylose isomerase (XI) from Streptomyces rubiginosus. In this paper, we show a rational approach for developing a large-scale crystallization process for XI. Firstly, we measured the crystal solubility in salt solutions with respect to salt concentration, temperature and pH. In ammonium sulfate the solubility of XI decreased logarithmically when increasing the salt concentration. Surprisingly, the XI crystals had a solubility minimum at low concentration of magnesium sulfate. The solubility of XI in 0.17 M magnesium sulfate was less than 0.5 g l -1. The solubility of XI increased logarithmically when increasing the temperature. We also found a solubility minimum around pH 7. This is far from the isoelectric point of XI (pH 3.95). Secondly, based on the solubility study, we developed a large-scale crystallization process for XI. In a simple and economical cooling crystallization of XI from 0.17 M magnesium sulfate solution, the recovery of crystalline active enzyme was over 95%. Moreover, we developed a process for production of uniform crystals and produced homogenous crystals with average crystal sizes between 12 and 360 μm.

Transcriptional and post-translational control of chlorophyll biosynthesis by dark-operative protochlorophyllide oxidoreductase in Norway spruce.

PubMed

Stolárik, Tibor; Hedtke, Boris; Šantrůček, Jiří; Ilík, Petr; Grimm, Bernhard; Pavlovič, Andrej

2017-05-01

Unlike angiosperms, gymnosperms use two different enzymes for the reduction of protochlorophyllide to chlorophyllide: the light-dependent protochlorophyllide oxidoreductase (LPOR) and the dark-operative protochlorophyllide oxidoreductase (DPOR). In this study, we examined the specific role of both enzymes for chlorophyll synthesis in response to different light/dark and temperature conditions at different developmental stages (cotyledons and needles) of Norway spruce (Picea abies Karst.). The accumulation of chlorophyll and chlorophyll-binding proteins strongly decreased during dark growth in secondary needles at room temperature as well as in cotyledons at low temperature (7 °C) indicating suppression of DPOR activity. The levels of the three DPOR subunits ChlL, ChlN, and ChlB and the transcripts of their encoding genes were diminished in dark-grown secondary needles. The low temperature had minor effects on the transcription and translation of these genes in cotyledons, which is suggestive for post-translational control in chlorophyll biosynthesis. Taking into account the higher solubility of oxygen at low temperature and oxygen sensitivity of DPOR, we mimicked low-temperature condition by the exposure of seedlings to higher oxygen content (33%). The treatment resulted in an etiolated phenotype of dark-grown seedlings, confirming an oxygen-dependent control of DPOR activity in spruce cotyledons. Moreover, light-dependent suppression of mRNA and protein level of DPOR subunits indicates that more efficiently operating LPOR takes over the DPOR function under light conditions, especially in secondary needles.

Angiogenesis mediated by soluble forms of E-selectin and vascular cell adhesion molecule-1

NASA Astrophysics Data System (ADS)

Koch, Alisa E.; Halloran, Margaret M.; Haskell, Catherine J.; Shah, Manisha R.; Polverini, Peter J.

1995-08-01

ENDOTHELIAL adhesion molecules facilitate the entry of leukocytes into inflamed tissues. This in turn promotes neovascularization, a process central to the progression of rheumatoid arthritis, tumour growth and wound repair1. Here we test the hypothesis that soluble endothelial adhesion molecules promote angiogenesis2á¤-4. Human recombinant soluble E-selectin and soluble vascular cell adhesion molecule-1 induced chemotaxis of human endothelial cells in vitro and were angiogenic in rat cornea. Soluble E-selectin acted on endothelial cells in part through a sialyl Lewis-X-dependent mechanism, while soluble vascular cell adhesion molecule-1 acted on endothelial cells in part through a very late antigen (VLA)-4 dependent mechanism. The chemotactic activity of rheumatoid synovial fluid for endothelial cells, and also its angiogenic activity, were blocked by antibodies to either soluble E-selectin or soluble vascular cell adhesion molecule-1. These results suggest a novel function for soluble endothelial adhesion molecules as mediators of angiogenesis.

Solubility of SC2O3 in NA3ALF6-K3ALF6-ALF3 Melts

NASA Astrophysics Data System (ADS)

Tian, Zhongliang; Hu, Xun; Lai, Yanqing; Yang, Shu; Ye, Shaolong; Li, Jie

The electrolyte with high solubility for Sc2O3 is very important to realize the preparation of Al-Sc master alloy by the molten salt electrolysis. The solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts is determined with an isothermal saturation method. The effects of KR (ratio of K3AlF6 to K3AlF6+Na3AlF6), the concentration of Al2O3 and the temperature on the solubility of Sc2O3 are also investigated. The results indicate that the solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts increases and then decreases with KR increasing. The solubility of Sc2O3 is 8.698 wt.% in (K3AlF6-Na3AlF6)(KR25%)-18 wt.%AlF3 melts at 940°C. The effect of temperature on the solubility is little, and the values are 8.575 wt.% and 8.762 wt.% respectively when the temperatures are 930°C and 960°C. The solubility decreases from 8.809 wt.% to 7.058 wt.% as the concentration of Al2O3 increases from 1.5 wt.% to 5.0 wt.% at 950°C.

pH-Dependent Solubility and Dissolution Behavior of Carvedilol--Case Example of a Weakly Basic BCS Class II Drug.

PubMed

Hamed, Rania; Awadallah, Areeg; Sunoqrot, Suhair; Tarawneh, Ola; Nazzal, Sami; AlBaraghthi, Tamadur; Al Sayyad, Jihan; Abbas, Aiman

2016-04-01

The objective of this study was to investigate the pH-dependent solubility and dissolution of weakly basic Biopharmaceutical Classification Systems (BCS) class II drugs, characterized by low solubility and high permeability, using carvedilol, a weak base with a pK a value of 7.8, as a model drug. A series of solubility and in vitro dissolution studies was carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH range of the GI from 1.2 to 7.8. The effect of ionic strength, buffer capacity, and buffer species of the dissolution media on the solubility and dissolution behavior of carvedilol was also investigated. The study revealed that carvedilol exhibited a typical weak base pH-dependent solubility profile with a high solubility at low pH (545.1-2591.4 μg/mL within the pH range 1.2-5.0) and low solubility at high pH (5.8-51.9 μg/mL within the pH range 6.5-7.8). The dissolution behavior of carvedilol was consistent with the solubility results, where carvedilol release was complete (95.8-98.2% released within 60 min) in media simulating the gastric fluid (pH 1.2-5.0) and relatively low (15.9-86.2% released within 240 min) in media simulating the intestinal fluid (pH 6.5-7.8). It was found that the buffer species of the dissolution media may influence the solubility and consequently the percentage of carvedilol released by forming carvedilol salts of varying solubilities. Carvedilol solubility and dissolution decreased with increasing ionic strength, while lowering the buffer capacity resulted in a decrease in carvedilol solubility and dissolution rate.

Chemical Properties of Brown Carbon Aerosol Generated at the Missoula Fire Sciences Laboratory

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Womack, C.; Franchin, A.; Middlebrook, A. M.; Wagner, N.; Manfred, K.

2017-12-01

Aerosol scattering and absorption are still among the largest uncertainties in quantifying radiative forcing. Biomass burning is a major source of light-absorbing carbonaceous aerosol in the United States. These aerosol are generally classified into two categories: black carbon (graphitic-like aerosol that absorbs broadly across the ultraviolet and visible spectral regions) and brown carbon (organic aerosol that absorbs strongly in the ultraviolet and near-visible spectral regions). The composition, volatility, and chemical aging of brown carbon are poorly known, but are important to understanding its radiative effects. We deployed three novel instruments to the Missoula Fire Sciences Laboratory in 2016 to measure brown carbon absorption: a photoacoustic spectrometer, broadband cavity enhanced spectrometer, and particle-into-liquid sampler coupled to a liquid waveguide capillary cell. The instruments sampled from a shared inlet with well-characterized dilution and thermal denuding. We sampled smoke from 32 controlled burns of fuels relevant to western U.S. wildfires. We use these measurements to determine the volatility of water-soluble brown carbon, and compare this to the volatility of water-soluble organic aerosol and total organic aerosol. We further examine the wavelength-dependence of the water-soluble brown carbon absorption as a function of denuder temperature. Together this gives new information about the solubility, volatility, and chemical composition of brown carbon.

Liquid-liquid equilibria of binary mixtures of a lipidic ionic liquid with hydrocarbons.

PubMed

Green, Blane D; Badini, Alexander J; O'Brien, Richard A; Davis, James H; West, Kevin N

2016-01-28

Although structurally diverse, many ionic liquids (ILs) are polar in nature due to the strong coulombic forces inherent in ionic compounds. However, the overall polarity of the IL can be tuned by incorporating significant nonpolar content into one or more of the constituent ions. In this work, the binary liquid-liquid equilibria of one such IL, 1-methyl-3-(Z-octadec-9-enyl)imidazolium bistriflimide, with several hydrocarbons (n-hexane, n-octane, n-decane, cyclohexane, methylcyclohexane, 1-octene) is measured over the temperature range 0-70 °C at ambient pressure using a combination of cloud point and gravimetric techniques. The phase behavior of the systems are similar in that they exhibit two phases: one that is 60-90 mole% hydrocarbon and a second phase that is nearly pure hydrocarbon. Each phase exhibits a weak dependence of composition on temperature (steep curve) above ∼10 °C, likely due to swelling and restructuring of the nonpolar nano-domains of the IL being limited by energetically unfavorable restructuring in the polar nano-domains. The solubility of the n-alkanes decreases with increasing size (molar volume), a trend that continues for the cyclic alkanes, for which upper critical solution temperatures are observed below 70 °C. 1-Octene is found to be more soluble than n-octane, attributable to a combination of its lower molar volume and slightly higher polarity. The COSMO-RS model is used to predict the T-x'-x'' diagrams and gives good qualitative agreement of the observed trends. This work presents the highest known solubility of n-alkanes in an IL to date and tuning the structure of the ionic liquid to maximize the size/shape trends observed may provide the basis for enhanced separations of nonpolar species.

The influence of cosolvent and heat on the solubility and reactivity of organophosphorous pesticide DNAPL alkaline hydrolysis.

PubMed

Muff, Jens; MacKinnon, Leah; Durant, Neal D; Bennedsen, Lars Frausing; Rügge, Kirsten; Bondgaard, Morten; Pennell, Kurt

2016-11-01

The presented research concerned the compatibility of cosolvents with in situ alkaline hydrolysis (ISAH) for treatment of organophosphorous (OPP) pesticide contaminated sites. In addition, the influence of moderate temperature heat increments was studied as a possible enhancement method. A complex dense non-aqueous phase liquid (DNAPL) of primarily parathion (~50 %) and methyl parathion (~15 %) obtained from the Danish Groyne 42 site was used as a contaminant source, and ethanol and propan-2-ol (0, 25, and 50 v/v%) was used as cosolvents in tap water and 0.34 M NaOH. Both cosolvents showed OPP solubility enhancement at 50 v/v% cosolvent content, with slightly higher OPP concentrations reached with propan-2-ol. Data on hydrolysis products did not show a clear trend with respect to alkaline hydrolysis reactivity in the presence of cosolvents. Results indicated that the hydrolysis rate of methyl-parathion (MP3) decreased with addition of cosolvent, whereas the hydrolysis rate of ethyl-parathion (EP3) remained constant, and overall indications were that the hydrolysis reactions were limited by the rate of hydrolysis rather than NAPL dissolution. In addition to cosolvents, the influence of low-temperature heating on ISAH was studied. Increasing reaction temperature from 10 to 30 °C provided an average rate of hydrolysis enhancement by a factor of 1.4-4.8 dependent on the base of calculation. When combining 50 v/v% cosolvent addition and heating to 30 °C, EP3 solubility was significantly enhanced and results for O,O-diethyl-thiophosphoric acid (EP2 acid) showed a significant enhancement of hydrolysis as well. However, this could not be supported by para-nitrophenol (PNP) data indicating the instability of this product in the presence of cosolvent.

Computer-aided method for the determination of Hansen solubility parameters. Application to the miscibility of refrigerating lubricant and new refrigerant

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

Remigy, J.C.; Nakache, E.; Brechot, P.D.

This article presents a method which allows one to find the Hansen solubility parameters by means of data processing. In the first part, the authors present the thermodynamical principle of Hansen parameters, and then they explain the model used to find parameters from experimental data. They validate the method by studying the solubility parameters of CFC-12 (dichlorodifluoromethane), HFC-134a (1,1,1,2-tetrafluoroethane), neopentylglycol esters, trimethylolpropane esters, dipentaerythritol esters, and pentaerythritol esters. Then, the variation of Hansen parameters are studied as well as the relation between the miscibility temperature (the temperature at which a blend passes from the miscible state to the immiscible state)more » and the interaction distance. The authors establish the critical interaction distance of HFC-134a which determines the solubility limit and they study its variation with temperature.« less

Molecularly designed water soluble, intelligent, nanosize polymeric carriers.

PubMed

Pişkin, Erhan

2004-06-11

Intelligent polymers, also referred as "stimuli-responsive polymers" undergo strong property changes (in shape, surface characteristics, solubility, etc.) when only small changes in their environment (changes in temperature, pH, ionic strength light, electrical and magnetic field, etc.). They have been used in several novel applications, drug delivery systems, tissue engineering scaffolds, bioseparation, biomimetic actuators, etc. The most popular member of these type of polymers is poly(N-isopropylacrylamide) (poly(NIPA)) which exhibits temperature-sensitive character, in which the polymer chains change from water-soluble coils to water-insoluble globules in aqueous solution as temperature increases above the lower critical solution temperature (LCST) of the polymer. Copolymerization of NIPA with acrylic acid (AAc) allows the synthesis of both pH and temperature-responsive copolymers. This paper summarizes some of our related studies in which NIPA and its copolymers were synthesized and used as intelligent carriers in diverse applications.

Solubility of methanol in low-temperature aqueous sulfuric acid and implications for atmospheric particle composition

NASA Technical Reports Server (NTRS)

Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

Using traditional Knudsen cell techniques, we find well-behaved Henry's law uptake of methanol in aqueous 45 - 70 wt% H2SO4 solutions at temperatures between 197 and 231 K. Solubility of methanol increases with decreasing temperature and increasing acidity, with an effective Henry's law coefficient ranging from 10(exp 5) - 10(exp 8) M/atm. Equilibrium uptake of methanol into sulfuric acid aerosol particles in the upper troposphere and lower stratosphere will not appreciably alter gas-phase concentrations of methanol. The observed room temperature reaction between methanol and sulfuric acid is too slow to provide a sink for gaseous methanol at the temperatures of the upper troposphere and lower stratosphere. It is also too slow to produce sufficient quantities of soluble reaction products to explain the large amount of unidentified organic material seen in particles of the upper troposphere.

Influences of end-point heating temperature on the quality attributes of chicken meat.

PubMed

Chumngoen, W; Chen, C F; Chen, H Y; Tan, F J

2016-12-01

This study aimed to evaluate the changes in physicochemical, textural and sensory characteristics of broiler (BR) and Taiwan native chicken (TNC) pectoralis muscle heated at temperatures of 50-95°C. With increasing temperature, cooking loss, collagen solubility, shear force value and hardness, of samples increased in both chicken breeds. Rapid decreases in protein solubility were observed when the meat was heated to 50°C and gradually decreased thereafter. Meat from BRs and native chickens performed differently upon heating in certain characteristics. TNC meat had longer cooking time and lower myofibrillar fragmentation index than BR meat did. TNC meat had higher collagen content, shear force values and springiness but lower collagen solubility than BR meat did. BR meat had significantly higher onset and end transition temperatures than TNC meat did. In BR meat, a sensory analysis revealed that moisture release decreased and chicken flavour increased with increasing temperature. Protein solubility, cooking loss and the texture of heated meat were highly correlated. This study scientifically assessed the performances of the two breeds of chickens with different thermal treatments; producers could utilise the information to produce poultry products with more desirable qualities.

In situ sum-frequency generation spectroscopy of ethylene-glycol and poly-N-isopropylacrylamide films

NASA Astrophysics Data System (ADS)

Kurz, Volker; Koelsch, Patrick

2009-03-01

Ethylene-glycol(EG)-based self-assembled monolayers (SAMs) are often used as a model systems for thin liquid films. Temperature series in heavy water were measured using a unique sample cell developed for in situ sum-frequency generation (SFG) spectroscopy experiments. Results obtained from model EG-SAMs with different lengths and terminating groups in various ionic solutions showed temperature-dependent changes in the molecular order. Films of poly-N-isopropylacrylamide(pNIPAM) were also characterized by in situ SFG spectroscopy in the CH, OH, OD and amide spectral regions under different polarization combinations. These systems have many applications as thermo-responsive polymers due to their ability to change solubility in water at the biologically relevant temperature of 32 C. This so-called lower critical solution temperature (LCST) phase transition was characterized in depth, allowing for the identification of the molecular groups involved in this process.

Base-Catalyzed Depolymerization of Biorefinery Lignins

DOE PAGES

Katahira, Rui; Mittal, Ashutosh; McKinney, Kellene; ...

2016-01-12

Lignocellulosic biorefineries will produce a substantial pool of lignin-enriched residues, which are currently slated to be burned for heat and power. Going forward, however, valorization strategies for residual solid lignin will be essential to the economic viability of modern biorefineries. To achieve these strategies, effective lignin depolymerization processes will be required that can convert specific lignin-enriched biorefinery substrates into products of sufficient value and market size. Base-catalyzed depolymerization (BCD) of lignin using sodium hydroxide and other basic media has been shown to be an effective depolymerization approach when using technical and isolated lignins relevant to the pulp and paper industry.more » Moreover, to gain insights in the application of BCD to lignin-rich, biofuels-relevant residues, here we apply BCD with sodium hydroxide at two catalyst loadings and temperatures of 270, 300, and 330 °C for 40 min to residual biomass from typical and emerging biochemical conversion processes. We obtained mass balances for each fraction from BCD, and characterized the resulting aqueous and solid residues using gel permeation chromatography, NMR, and GC–MS. When taken together, these results indicate that a significant fraction (45–78%) of the starting lignin-rich material can be depolymerized to low molecular weight, water-soluble species. The yield of the aqueous soluble fraction depends significantly on biomass processing method used prior to BCD. Namely, dilute acid pretreatment results in lower water-soluble yields compared to biomass processing that involves no acid pretreatment. We also find that the BCD product selectivity can be tuned with temperature to give higher yields of methoxyphenols at lower temperature, and a higher relative content of benzenediols with a greater extent of alkylation on the aromatic rings at higher temperature. Our study shows that residual, lignin-rich biomass produced from conventional and emerging biochemical conversion processes can be depolymerized with sodium hydroxide to produce significant yields of low molecular weight aromatics that potentially can be upgraded to fuels or chemicals.« less

Base-Catalyzed Depolymerization of Biorefinery Lignins

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

Katahira, Rui; Mittal, Ashutosh; McKinney, Kellene

Lignocellulosic biorefineries will produce a substantial pool of lignin-enriched residues, which are currently slated to be burned for heat and power. Going forward, however, valorization strategies for residual solid lignin will be essential to the economic viability of modern biorefineries. To achieve these strategies, effective lignin depolymerization processes will be required that can convert specific lignin-enriched biorefinery substrates into products of sufficient value and market size. Base-catalyzed depolymerization (BCD) of lignin using sodium hydroxide and other basic media has been shown to be an effective depolymerization approach when using technical and isolated lignins relevant to the pulp and paper industry.more » Moreover, to gain insights in the application of BCD to lignin-rich, biofuels-relevant residues, here we apply BCD with sodium hydroxide at two catalyst loadings and temperatures of 270, 300, and 330 °C for 40 min to residual biomass from typical and emerging biochemical conversion processes. We obtained mass balances for each fraction from BCD, and characterized the resulting aqueous and solid residues using gel permeation chromatography, NMR, and GC–MS. When taken together, these results indicate that a significant fraction (45–78%) of the starting lignin-rich material can be depolymerized to low molecular weight, water-soluble species. The yield of the aqueous soluble fraction depends significantly on biomass processing method used prior to BCD. Namely, dilute acid pretreatment results in lower water-soluble yields compared to biomass processing that involves no acid pretreatment. We also find that the BCD product selectivity can be tuned with temperature to give higher yields of methoxyphenols at lower temperature, and a higher relative content of benzenediols with a greater extent of alkylation on the aromatic rings at higher temperature. Our study shows that residual, lignin-rich biomass produced from conventional and emerging biochemical conversion processes can be depolymerized with sodium hydroxide to produce significant yields of low molecular weight aromatics that potentially can be upgraded to fuels or chemicals.« less

Solubility of pyromorphite Pb 5(PO 4) 3Cl at 5–65°C and its experimentally determined thermodynamic parameters

DOE PAGES

Topolska, Justyna; Manecki, Maciej; Bajda, Tomasz; ...

2016-03-19

Here, the solubility of synthetic pyromorphite Pb 5(PO 4) 3Cl was determined in a series of dissolution experiments conducted at 5–65 °C and at pH = 2.0. The equilibrium was established within 4 months. The dissolution of pyromorphite was congruent at all the temperatures, and the measured solubility product log K sp,298 for the dissolution reaction: Pb 5(PO 4) 3Cl ⇌ 5Pb 2+ + 3PO 4 3- + Cl - was determined to be –79.6 ± 0.15. The equilibrium ion activity product of pyromorphite increased with temperature, indicating a positive enthalpy of the dissolution reaction in the temperature range frommore » 5 to 65 °C. The temperature dependence of the log K sp was nonlinear: log K sp = A – B/T + D log(T), where A = 478.77 ± 136.62, B = 29,378 ± 6215, and D = –185.81 ± 46.77. This allowed for calculation of ΔG° r = 454.0 ± 1.7 kJ·mol –1, ΔH° r = 101.8 ± 6.0 J·mol –1·K –1, ΔC° p,r = –1545 ± 388.9 J·mol –1·K –1, and ΔS° r = –1181 ± 382 J·mol –1·K –1 of the dissolution reaction. Using these values and the published standard state quantities for constituent ions, the values of ΔG° f = –3764.3 ± 3.5 kJ·mol –1, ΔH° f = –4108.4 ± 7.9 J·mol –1·K –1, S° f = 622 ± 382 J·mol –1·K –1, and C° pf = 402 ± 398 J·mol –1·K –1 were calculated for synthetic pyromorphite Pb 5(PO 4) 3Cl.« less

Formulation of thermoresponsive and buccal adhesive in situ gel for treatment of oral thrush containing poorly water soluble drug bifonazole.

PubMed

Patel, Dimendra; Patel, Dipti; Prajapati, Jatin; Patel, Umang; Patel, Vijay

2012-03-01

The aim of the present work is to formulate and evaluate in situ oral topical gels of poorly water soluble drug Bifonazole based on temperature induced systems for the treatment of oral candidiasis. Bifonazole is poorly water soluble and low permeable drug means it's belongs to BCS Class IV. Due to its poor water solubility, it necessary to enhance solubility in water by make complex with Beta- Cyclodextrin (Drug to βCyclo Dextrine ratio is 1:1). After in situ gel preparation done by using Poloxamer (10% and 15%w/w) along with carbopol 934 (0.2 to 1.0% w/w) and Bifonazole - β CD complex (1%w/w). The formulations were evaluated for physiochemical parameter, gelation Temperature, viscosity, gel strength, content uniformity mucoadhesive force, Diffusion Study.

Formulation of thermoresponsive and buccal adhesive in situ gel for treatment of oral thrush containing poorly water soluble drug bifonazole

PubMed Central

Patel, Dimendra; Patel, Dipti; Prajapati, Jatin; Patel, Umang; Patel, Vijay

2012-01-01

The aim of the present work is to formulate and evaluate in situ oral topical gels of poorly water soluble drug Bifonazole based on temperature induced systems for the treatment of oral candidiasis. Bifonazole is poorly water soluble and low permeable drug means it's belongs to BCS Class IV. Due to its poor water solubility, it necessary to enhance solubility in water by make complex with Beta- Cyclodextrin (Drug to βCyclo Dextrine ratio is 1:1). After in situ gel preparation done by using Poloxamer (10% and 15%w/w) along with carbopol 934 (0.2 to 1.0% w/w) and Bifonazole – β CD complex (1%w/w). The formulations were evaluated for physiochemical parameter, gelation Temperature, viscosity, gel strength, content uniformity mucoadhesive force, Diffusion Study. PMID:23066185

Low-Sulfate Seawater Injection into Oil Reservoir to Avoid Scaling Problem

NASA Astrophysics Data System (ADS)

Merdhah, Amer Badr Bin; Mohd Yassin, Abu Azam

This study presents the results of laboratory experiments carried out to investigate the formation of calcium, strontium and barium sulfates from mixing Angsi seawater or low sulfate seawater with the following sulfate contents (75, 50, 25, 5 and 1%) and formation water contain high concentration of calcium, strontium and barium ions at various temperatures (40-90°C) and atmospheric pressure. The knowledge of solubility of common oil field scale formation and how their solubilities are affected by changes in salinity and temperatures is also studied. Results show a large of precipitation occurred in all jars containing seawater while the amount of precipitation decreased when the low sulfate seawater was used. At higher temperatures the mass of precipitation of CaSO4 and SrSO4 scales increases and the mass of precipitation of BaSO4 scale decreases since the solubilities of CaSO4 and SrSO4 scales decreases and the solubility of BaSO4 increases with increasing temperature. It can be concluded that even at sulfate content of 1% there may still be a scaling problem.

How cocrystals of weakly basic drugs and acidic coformers might modulate solubility and stability.

PubMed

Kuminek, G; Rodríguez-Hornedo, N; Siedler, S; Rocha, H V A; Cuffini, S L; Cardoso, S G

2016-04-30

Cocrystals of a weakly basic drug (nevirapine) with acidic coformers are shown to alter the solubility dependence on pH, and to exhibit a pHmax above which a less soluble cocrystal becomes more soluble than the drug. The cocrystal solubility advantage can be dialed up or down by solution pH.

Effect of Excipients on Liquid-Liquid Phase Separation and Aggregation in Dual Variable Domain Immunoglobulin Protein Solutions.

PubMed

Raut, Ashlesha S; Kalonia, Devendra S

2016-03-07

Liquid-liquid phase separation (LLPS) and aggregation can reduce the physical stability of therapeutic protein formulations. On undergoing LLPS, the protein-rich phase can promote aggregation during storage due to high concentration of the protein. Effect of different excipients on aggregation in protein solution is well documented; however data on the effect of excipients on LLPS is scarce in the literature. In this study, the effect of four excipients (PEG 400, Tween 80, sucrose, and hydroxypropyl beta-cyclodextrin (HPβCD)) on liquid-liquid phase separation and aggregation in a dual variable domain immunoglobulin protein solution was investigated. Sucrose suppressed both LLPS and aggregation, Tween 80 had no effect on either, and PEG 400 increased LLPS and aggregation. Attractive protein-protein interactions and liquid-liquid phase separation decreased with increasing concentration of HPβCD, indicating its specific binding to the protein. However, HPβCD had no effect on the formation of soluble aggregates and fragments in this study. LLPS and aggregation are highly temperature dependent; at low temperature protein exhibits LLPS, at high temperature protein exhibits aggregation, and at an intermediate temperature both phenomena occur simultaneously depending on the solution conditions.

Estimating the Aqueous Solubility of Pharmaceutical Hydrates

PubMed Central

Franklin, Stephen J.; Younis, Usir S.; Myrdal, Paul B.

2016-01-01

Estimation of crystalline solute solubility is well documented throughout the literature. However, the anhydrous crystal form is typically considered with these models, which is not always the most stable crystal form in water. In this study an equation which predicts the aqueous solubility of a hydrate is presented. This research attempts to extend the utility of the ideal solubility equation by incorporating desolvation energetics of the hydrated crystal. Similar to the ideal solubility equation, which accounts for the energetics of melting, this model approximates the energy of dehydration to the entropy of vaporization for water. Aqueous solubilities, dehydration and melting temperatures, and log P values were collected experimentally and from the literature. The data set includes different hydrate types and a range of log P values. Three models are evaluated, the most accurate model approximates the entropy of dehydration (ΔSd) by the entropy of vaporization (ΔSvap) for water, and utilizes onset dehydration and melting temperatures in combination with log P. With this model, the average absolute error for the prediction of solubility of 14 compounds was 0.32 log units. PMID:27238488

A numerical scheme to calculate temperature and salinity dependent air-water transfer velocities for any gas

NASA Astrophysics Data System (ADS)

Johnson, M. T.

2010-10-01

The ocean-atmosphere flux of a gas can be calculated from its measured or estimated concentration gradient across the air-sea interface and the transfer velocity (a term representing the conductivity of the layers either side of the interface with respect to the gas of interest). Traditionally the transfer velocity has been estimated from empirical relationships with wind speed, and then scaled by the Schmidt number of the gas being transferred. Complex, physically based models of transfer velocity (based on more physical forcings than wind speed alone), such as the NOAA COARE algorithm, have more recently been applied to well-studied gases such as carbon dioxide and DMS (although many studies still use the simpler approach for these gases), but there is a lack of validation of such schemes for other, more poorly studied gases. The aim of this paper is to provide a flexible numerical scheme which will allow the estimation of transfer velocity for any gas as a function of wind speed, temperature and salinity, given data on the solubility and liquid molar volume of the particular gas. New and existing parameterizations (including a novel empirical parameterization of the salinity-dependence of Henry's law solubility) are brought together into a scheme implemented as a modular, extensible program in the R computing environment which is available in the supplementary online material accompanying this paper; along with input files containing solubility and structural data for ~90 gases of general interest, enabling the calculation of their total transfer velocities and component parameters. Comparison of the scheme presented here with alternative schemes and methods for calculating air-sea flux parameters shows good agreement in general. It is intended that the various components of this numerical scheme should be applied only in the absence of experimental data providing robust values for parameters for a particular gas of interest.

Space Environmentally Stable Polyimides and Copolyimides

NASA Technical Reports Server (NTRS)

Watson, Kent A.; Connell, John W.

2000-01-01

Polyimides with a unique combination of properties including low color in thin films, atomic oxygen (AO), ultra-violet (UV) radiation resistance, solubility in organic solvents in the imide form, high glass transition (T(sub g)) temperatures and high thermal stability have been prepared and characterized. The polymers were prepared by reacting a novel aromatic diamine with aromatic dianhydrides in a polar aprotic solvent. The solubility of the polymers in the imide form as well as the color density of thin films were dependent upon the chemical structure of the dianhydride. Several thin films (25-50 mm thick) prepared by solution casting of amide acid or imide solutions exhibited very low color and high optical transparency (approximately 90%) as determined by UV/visible spectroscopy. The polymers exhibited T(sub g)s >200 C depending upon the structure of the dianhydride and temperatures of 5% weight loss approximately 500C in air as determined by dynamic thermogravimetric analysis. Thin films coated with silver/inconel were exposed to a high fluence of AO and 1000 equivalent solar hours of UV radiation. The effects of these exposures on optical properties were minor. These space environmentally durable polymers are potentially useful in a variety of applications on spacecraft such as thin film membranes on antennas, second-surface mirrors, thermal/optical coatings and multi-layer thermal insulation (MLI) blanket materials. The chemistry, physical and mechanical properties of the polymers as well as their responses to AO and UV exposure will be discussed.

Formation of bubbly horizon in liquid-saturated porous medium by surface temperature oscillation.

PubMed

Goldobin, Denis S; Krauzin, Pavel V

2015-12-01

We study nonisothermal diffusion transport of a weakly soluble substance in a liquid-saturated porous medium in contact with a reservoir of this substance. The surface temperature of the porous medium half-space oscillates in time, which results in a decaying solubility wave propagating deep into the porous medium. In this system, zones of saturated solution and nondissolved phase coexist with ones of undersaturated solution. The effect is first considered for the case of annual oscillation of the surface temperature of water-saturated ground in contact with the atmosphere. We reveal the phenomenon of formation of a near-surface bubbly horizon due to temperature oscillation. An analytical theory of the phenomenon is developed. Further, the treatment is extended to the case of higher frequency oscillations and the case of weakly soluble solids and liquids.

Solubility and crystal nucleation in organic solvents of two polymorphs of curcumin.

PubMed

Liu, Jin; Svärd, Michael; Hippen, Perschia; Rasmuson, Åke C

2015-07-01

Two crystal polymorphs of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) have been obtained by crystallization from ethanol (EtOH) solution. The polymorphs have been characterized by differential scanning calorimetry, infrared spectroscopy, and X-ray powder diffraction and shown to be the previously described forms I and III. The solubility of both polymorphs in EtOH and of one polymorph in ethyl acetate (EA) has been measured between 10°C and 50°C with a gravimetric method. Primary nucleation of curcumin from EtOH solution has been investigated in 520 constant temperature crystallization experiments in sealed, magnetically stirred vials under different conditions of supersaturation, temperature, and agitation rate. By a thermodynamic analysis of the melting data and solubility of form I, the solid-state activity is estimated from 10°C up to the melting point. The solubility is lower in EtOH than in EA, and in both solvents, a positive deviation from Raoult's law is observed. Form I has lower solubility than form III and is accordingly thermodynamically more stable over the investigated temperature interval. Extrapolation of solubility regression models indicates that there should be a low-temperature enantiotropic transition point, below which form I will be metastable. By slurry conversion experiments, it is established that this temperature is below -30°C. All nucleation experiments resulted in the stable form I. The induction time is observed to decrease with increasing agitation rate up to a certain point, and then increase with further increasing agitation rate; a trend previously observed for other compounds. By correlating the induction time data obtained at different supersaturation and temperature, the interfacial energy of form I in EtOH is estimated to be 3.0 mJ/m(2) . © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids.

PubMed

Finotello, Alexia; Bara, Jason E; Narayan, Suguna; Camper, Dean; Noble, Richard D

2008-02-28

This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) at 40 degrees C and low pressures (approximately 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % [C2mim][BF4] in [C2mim][Tf2N]. Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO2 with N2 or CH4 in pure [C2mim][BF4] can be enhanced by adding 5 mol % [C2mim][Tf2N].

Solubility of xenon in amino-acid solutions. II. Nine less-soluble amino acids

NASA Astrophysics Data System (ADS)

Kennan, Richard P.; Himm, Jeffrey F.; Pollack, Gerald L.

1988-05-01

Ostwald solubility (L) of xenon gas, as the radioisotope 133Xe, has been measured as a function of solute concentration, at 25.0 °C, in aqueous solutions of nine amino acids. The amino-acid concentrations investigated covered much of their solubility ranges in water, viz., asparagine monohydrate (0-0.19 M), cysteine (0-1.16 M), glutamine (0-0.22 M), histidine (0-0.26 M), isoleucine (0-0.19 M), methionine (0-0.22 M), serine (0-0.38 M), threonine (0-1.4 M), and valine (0-0.34 M). We have previously reported solubility results for aqueous solutions of six other, generally more soluble, amino acids (alanine, arginine, glycine, hydroxyproline, lysine, and proline), of sucrose and sodium chloride. In general, L decreases approximately linearly with increasing solute concentration in these solutions. If we postulate that the observed decreases in gas solubility are due to hydration, the results under some assumptions can be used to calculate hydration numbers (H), i.e., the number of H2O molecules associated with each amino-acid solute molecule. The average values of hydration number (H¯) obtained at 25.0 °C are 15.3±1.5 for asparagine, 6.8±0.3 for cysteine, 11.5±1.1 for glutamine, 7.3±0.7 for histidine, 5.9±0.4 for isoleucine, 10.6±0.8 for methionine, 11.2±1.3 for serine, 7.7± 1.0 for threonine, and 6.6±0.6 for valine. We have also measured the temperature dependence of solubility L(T) from 5-40 °C for arginine, glycine, and proline, and obtained hydration numbers H¯(T) in this range. Between 25-40 °C, arginine has an H¯ near zero. This may be evidence for an attractive interaction between xenon and arginine molecules in aqueous solution.

Advances in first-principles calculations of thermodynamic properties of planetary materials (Invited)

NASA Astrophysics Data System (ADS)

Wilson, H. F.

2013-12-01

First-principles atomistic simulation is a vital tool for understanding the properties of materials at the high-pressure high-temperature conditions prevalent in giant planet interiors, but properties such as solubility and phase boundaries are dependent on entropy, a quantity not directly accessible in simulation. Determining entropic properties from atomistic simulations is a difficult problem typically requiring a time-consuming integration over molecular dynamics trajectories. Here I will describe recent advances in first-principles thermodynamic calculations which substantially increase the simplicity and efficiency of thermodynamic integration and make entropic properties more readily accessible. I will also describe the use of first-principles thermodynamic calculations for understanding problems including core solubility in gas giants and superionic phase changes in ice giants, as well as future prospects for combining first-principles thermodynamics with planetary-scale models to help us understand the origin and consequences of compositional inhomogeneity in giant planet interiors.

Stimuli-Responsive, Shape-Transforming Nanostructured Particles.

PubMed

Lee, Junhyuk; Ku, Kang Hee; Kim, Mingoo; Shin, Jae Man; Han, Junghun; Park, Chan Ho; Yi, Gi-Ra; Jang, Se Gyu; Kim, Bumjoon J

2017-08-01

Development of particles that change shape in response to external stimuli has been a long-thought goal for producing bioinspired, smart materials. Herein, the temperature-driven transformation of the shape and morphology of polymer particles composed of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers (BCPs) and temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) surfactants is reported. PNIPAM acts as a temperature-responsive surfactant with two important roles. First, PNIPAM stabilizes oil-in-water droplets as a P4VP-selective surfactant, creating a nearly neutral interface between the PS and P4VP domains together with cetyltrimethylammonium bromide, a PS-selective surfactant, to form anisotropic PS-b-P4VP particles (i.e., convex lenses and ellipsoids). More importantly, the temperature-directed positioning of PNIPAM depending on its solubility determines the overall particle shape. Ellipsoidal particles are produced above the critical temperature, whereas convex lens-shaped particles are obtained below the critical temperature. Interestingly, given that the temperature at which particle shape change occurs depends solely on the lower critical solution temperature (LCST) of the polymer surfactants, facile tuning of the transition temperature is realized by employing other PNIPAM derivatives with different LCSTs. Furthermore, reversible transformations between different shapes of PS-b-P4VP particles are successfully demonstrated using a solvent-adsorption annealing with chloroform, suggesting great promise of these particles for sensing, smart coating, and drug delivery applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions

NASA Technical Reports Server (NTRS)

Leu, Ming-Taun

2006-01-01

We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

Physical properties of ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various anions and the bis(trifluoromethylsulfonyl)imide anion with various cations.

PubMed

Jin, Hui; O'Hare, Bernie; Dong, Jing; Arzhantsev, Sergei; Baker, Gary A; Wishart, James F; Benesi, Alan J; Maroncelli, Mark

2008-01-10

Physical properties of 4 room-temperature ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various perfluorinated anions and the bis(trifluoromethylsulfonyl)imide (Tf2N-) anion with 12 pyrrolidinium-, ammonium-, and hydroxyl-containing cations are reported. Electronic structure methods are used to calculate properties related to the size, shape, and dipole moment of individual ions. Experimental measurements of phase-transition temperatures, densities, refractive indices, surface tensions, solvatochromic polarities based on absorption of Nile Red, 19F chemical shifts of the Tf2N- anion, temperature-dependent viscosities, conductivities, and cation diffusion coefficients are reported. Correlations among the measured quantities as well as the use of surface tension and molar volume for estimating Hildebrand solubility parameters of ionic liquids are also discussed.

Advantage of low-temperature hydrothermal synthesis to grow stoichiometric crednerite crystals

NASA Astrophysics Data System (ADS)

Poienar, Maria; Martin, Christine; Lebedev, Oleg I.; Maignan, Antoine

2018-06-01

This work reports a new approach for the growth of stoichiometric crednerite CuMnO2 crystals. The hydrothermal reaction, starting from soluble metal sulphates as precursors, is assisted by ethylene glycol and the formation of crednerite is found to depend strongly on pH and temperature. This method allows obtaining small hexagonal platelets with the larger dimension about 1.0-1.5 μm and with a composition characterized by a Cu/Mn ratio of 1. Thus, these crystals differ from the needle-like millimetric ones obtained by the flux technique for which the composition departs from the expected one and is close to Cu1.04Mn0.96. This monitoring of the cationic composition in crednerite, using hydrothermal synthesis, is important as the Cu/Mn ratio controls the low temperature antiferromagnetic ground-state.

Solubility of crude oil in methane as a function of pressure and temperature

USGS Publications Warehouse

Price, L.C.; Wenger, L.M.; Ging, T.; Blount, C.W.

1983-01-01

The solubility of a 44?? API (0.806 sp. gr.) whole crude oil has been measured in methane with water present at temperatures of 50 to 250??C and pressures of 740 to 14,852 psi, as have the solubilities of two high molecular weight petroleum distillation fractions at temperatures of 50 to 250??C and pressures of 4482 to 25,266 psi. Both increases in pressure and temperature increase the solubility of crude oil and petroleum distillation fractions in methane, the effect of pressure being greater than that of temperature. Unexpectedly high solubility levels (0.5-1.5 grams of oil per liter of methane-at laboratory temperature and pressure) were measured at moderate conditions (50-200??C and 5076-14504 psi). Similar results were found for the petroleum distillation fractions, one of which was the highest molecular weight material of petroleum (material boiling above 266??C at 6 microns pressure). Unexpectedly mild conditions (100??C and 15,200 psi; 200??C and 7513 psi) resulted in cosolubility of crude oil and methane. Under these conditions, samples of the gas-rich phase gave solubility values of 4 to 5 g/l, or greater. Qualitative analyses of the crude-oil solute samples showed that at low pressure and temperature equilibration conditions, the solute condensate would be enriched in C5-C15 range hydrocarbons and in saturated hydrocarbons in the C15+ fraction. With increases in temperature and especially pressure, these tendencies were reversed, and the solute condensate became identical to the starting crude oil. The data of this study, compared to that of previous studies, shows that methane, with water present, has a much greater carrying capacity for crude oil than in dry systems. The presence of water also drastically lowers the temperature and pressure conditions required for cosolubility. The data of this and/or previous studies demonstrate that the addition of carbon dioxide, ethane, propane, or butane to methane also has a strong positive effect on crude oil solubility, as does the presence of fine grained rocks. The n-paraffin distributions (as well as the overall composition) of the solute condensates are controlled by the temperature and pressure of solution and exsolution, as well as by the composition of the original starting material. It appears quite possible that primary migration by gaseous solution could 'strip' a source rock of crude-oil like components leaving behind a bitumen totally unlike the migrated crude oil. The data of this study demonstrate previous criticisms of primary petroleum migration by gas solution are invalid; that primary migration by gaseous solution cannot occur because methane cannot dissolve sufficient volumes of crude oil or cannot dissolve the highest molecular weight components of petroleum (tars and asphaltenes). ?? 1983.

How cocrystals of weakly basic drugs and acidic coformers might modulate solubility and stability

PubMed Central

Kuminek, G.; Rodríguez-Hornedo, N.; Siedler, S.; Rocha, H. V. A.; Cuffini, S. L.; Cardoso, S. G.

2016-01-01

Cocrystals of a weakly basic drug (nevirapine) with acidic coformers are shown to alter the solubility dependence on pH, and to exhibit a pHmax above which a less soluble cocrystal becomes more soluble than the drug. The cocrystal solubility advantage can be dialed up or down by solution pH. PMID:27042997

The solubility-permeability interplay and oral drug formulation design: Two heads are better than one.

PubMed

Dahan, Arik; Beig, Avital; Lindley, David; Miller, Jonathan M

2016-06-01

Poor aqueous solubility is a major challenge in today's biopharmaceutics. While solubility-enabling formulations can significantly increase the apparent solubility of the drug, the concomitant effect on the drug's apparent permeability has been largely overlooked. The mathematical equation to describe the membrane permeability of a drug comprises the membrane/aqueous partition coefficient, which in turn is dependent on the drug's apparent solubility in the GI milieu, suggesting that the solubility and the permeability are closely related, exhibit a certain interplay between them, and treating the one irrespectively of the other may be insufficient. In this article, an overview of this solubility-permeability interplay is provided, and the available data is analyzed in the context of the effort to maximize the overall drug exposure. Overall, depending on the type of solubility-permeability interplay, the permeability may decrease, remain unchanged, and even increase, in a way that may critically affect the formulation capability to improve the overall absorption. Therefore, an intelligent design of solubility-enabling formulation needs to consider both the solubility afforded by the formulation and the permeability in the new luminal environment resulting from the formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Urban Enhancement of PM10 Bioaerosol Tracers Relative to Background Locations in the Midwestern United States

PubMed Central

Rathnayake, Chathurika M.; Metwali, Nervana; Baker, Zach; Jayarathne, Thilina; Kostle, Pamela A.; Thorne, Peter S.; O’Shaughnessy, Patrick T.; Stone, Elizabeth A.

2016-01-01

Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and co-pollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM10) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012. Endotoxins from gram negative bacteria (and a few gram positive bacteria), water-soluble proteins, and tracers for fungal spores (fungal glucans, arabitol and mannitol) were ubiquitous and showed significant seasonal variation and dependence on temperature. Fungal spores were elevated in spring and peaked in summer, following the seasonal growing cycle, while endotoxins peaked in autumn during the row crop harvesting season. Paired comparisons of bioaerosols in urban and background sites revealed significant urban enhancements in PM10, fungal glucans, endotoxins and water-soluble proteins relative to background locations, such that urban populations have a greater outdoor exposure to bioaerosols. These bioaerosols contribute, in part, to the urban excesses in PM10. Higher bioaerosol mass fractions in urban areas relative to background sites indicate that urban areas serve as a source of bioaerosols. Similar urban enhancements in water-soluble calcium and its correlation with bioaerosol tracers point towards wind-blown soil as an important source of bioaerosols in urban areas. PMID:27672535

Urban Enhancement of PM10 Bioaerosol Tracers Relative to Background Locations in the Midwestern United States.

PubMed

Rathnayake, Chathurika M; Metwali, Nervana; Baker, Zach; Jayarathne, Thilina; Kostle, Pamela A; Thorne, Peter S; O'Shaughnessy, Patrick T; Stone, Elizabeth A

2016-05-16

Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and co-pollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM 10 ) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012. Endotoxins from gram negative bacteria (and a few gram positive bacteria), water-soluble proteins, and tracers for fungal spores (fungal glucans, arabitol and mannitol) were ubiquitous and showed significant seasonal variation and dependence on temperature. Fungal spores were elevated in spring and peaked in summer, following the seasonal growing cycle, while endotoxins peaked in autumn during the row crop harvesting season. Paired comparisons of bioaerosols in urban and background sites revealed significant urban enhancements in PM 10 , fungal glucans, endotoxins and water-soluble proteins relative to background locations, such that urban populations have a greater outdoor exposure to bioaerosols. These bioaerosols contribute, in part, to the urban excesses in PM 10 . Higher bioaerosol mass fractions in urban areas relative to background sites indicate that urban areas serve as a source of bioaerosols. Similar urban enhancements in water-soluble calcium and its correlation with bioaerosol tracers point towards wind-blown soil as an important source of bioaerosols in urban areas.

SiO2 Solubility in Rutile at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

Ren, Y.; Fei, Y.; Yang, J.; Bai, W. J.; Xu, Z. Q.

2005-12-01

Silicon-bearing rutile has been found in nature. The extent of SiO2 solubility in rutile and the nature of its origin are still not clear. At high pressure, SiO2 takes rutile structure with 6-coordinated Si. The high-pressure phase of SiO2 may enhance its solubility in rutile because possible isovalent exchange in octahedral site. In this study, we report new experimental results on SiO2 solubility in rutile up to 23 GPa and 2273 K. Starting materials are mixtures of powdered TiO2 and SiO2, with compositions of (Ti0.5Si0.5)O2, (Ti0.93Si0.07)O2, and (Ti0.75Si0.25)O2. The mixtures were loaded into either a platinum capsules (for a 10/5 assembly) or a rhenium capsules (for an 8/3 assembly). The experiments were carried out using multi-anvil high-pressure apparatus with rhenium resistance heater. Sample temperatures were measured with a type-C thermocouple. The quenched samples were recovered and prepared for electron microprobe analyses. TiO2-rich and SiO2-rich phases are produced in all the quenched samples. The analyses showed that the solubility of SiO2 in rutile increases with increasing pressure, from 1.5 wt% SiO2 at 10 GPa to 3.8 wt% SiO2 at 23 GPa for a given temperature of 2073 K. The solubility also increases with increasing temperature, from 0.5 wt% SiO2 at 1773 K to 4.5 wt% SiO2 at 2273 K for a given pressure of 18 GPa. On the other hand, the solubility of TiO2 in coesite or stishovite is very limited, with an average of 0.6 wt% TiO2 over the experimental P-T ranges. Lower oxygen fugacity decreases the solubility of SiO2 in rutile, whereas water has little effect on the solubility of SiO2 in rutile. Our experimental data are extreme useful for determine the depth of origin for the SiO2-bearing rutile in nature.

Phase diagram of a crystalline protein: Determination of the solubility of concanavalin A by a microquantitation assay

NASA Astrophysics Data System (ADS)

Mikol, Vincent; Giegé, Richard

1989-09-01

A quick and miniature method has been devised for determining protein solubility and used to investigate the equilibrium solubility of concanavalin A from the Jack Bean with its crystals as a function of ammonium sulfate concentration, temperature and pH. The crystals were characterized by X-ray diffraction and their morphologies related to the corresponding solubilities. The protein solution concentration was estimated out of small crystallizing drops using a rapid and sensitive microassay. Measurements of protein quantity were carried out in 96-well microplates in an automatic spectrophotometer. The resulting phase diagram has permitted to analyse the solubility of concanavalin A, to estimate supersaturation and to devise readily new ways of crystal growth of this lectin, namely by pH and temperature variations. Moreover, the approach is proved to be a valuable tool to design crystallization experiments of new molecules and to improve and control protein crystal growth.

Solubility of HCL in sulfuric acid at stratospheric temperatures

NASA Technical Reports Server (NTRS)

Williams, Leah R.; Golden, David M.

1993-01-01

The solubility of HCl in sulfuric acid was measured using a Knudsen cell technique. Effective Henry's law constants are reported for sulfuric acid concentrations between 50 and 60 weight percent and for temperatures between 220 and 230 K. The measured values indicate that very little HCl will be dissolved in the stratospheric sulfate aerosol particles.

Blended polymer materials extractable with supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Cai, Mei

Supercritical carbon dioxide is drawing more and more attention because of its unique solvent properties along with being environmentally friendly. Historically most of the commercial interests of supercritical carbon dioxide extraction are in the food industry, pharmaceutical industry, environmental preservation and polymer processing. Recently attention has shifted from the extraction of relatively simple molecules to more complex systems with a much broader range of physical and chemical transformations. However the available data show that a lot of commercially valuable substances are not soluble in supercritical carbon dioxide due to their polar structures. This fact really limits the application of SCF extraction technology to much broader industrial applications. Therefore, the study of a polymer's solubility in a given supercritical fluid and its thermodynamic behavior becomes one of the most important research topics. The major objective of this dissertation is to develop a convenient and economic way to enhance the polymer's solubility in supercritical carbon dioxide. Further objective is to innovate a new process of making metal casting parts with blended polymer materials developed in this study. The key technique developed in this study to change a polymer's solubility in SCF CO2 is to thermally blend a commercially available and CO2 non-soluble polymer material with a low molecular weight CO2 soluble organic chemical that acts as a co-solute. The mixture yields a plastic material that can be completely solubilized in SCF CO2 over a range of temperatures and pressures. It also exhibits a variety of physical properties (strength, hardness, viscosity, etc.) depending on variations in the mixture ratio. The three organic chemicals investigated as CO2 soluble materials are diphenyl carbonate, naphthalene, and benzophenone. Two commercial polymers, polyethylene glycol and polystyrene, have been investigated as CO2 non-soluble materials. The chemical, physical, thermal, and phase behavior of the blended polymers studied in this dissertation includes solubility in SCF CO2, the melt viscosity, the melting temperature depression, and phase equilibrium under SCF conditions. Several hypotheses are investigated to determine which mechanism plays the major role in the extraction. Finally a novel metal casting process is discussed with the materials developed in this study. This new method utilizes an adhesive or binder film composition for the purpose of building up a casting pattern of resin-bonded aggregate particles. The pattern is then encased in a conventional rigid shell mold that is not susceptible to degradation by SCF CO2. The pattern is then disintegrated within an unaffected mold by exposure to SCF CO 2. This is an efficient and low cost method of making patterns and molds, especially for the casting of a relatively low number of parts such as in prototype evaluations.

Thermodynamic Stability Analysis of Tolbutamide Polymorphs and Solubility in Organic Solvents.

PubMed

Svärd, Michael; Valavi, Masood; Khamar, Dikshitkumar; Kuhs, Manuel; Rasmuson, Åke C

2016-06-01

Melting temperatures and enthalpies of fusion have been determined by differential scanning calorimetry (DSC) for 2 polymorphs of the drug tolbutamide: FI(H) and FV. Heat capacities have been determined by temperature-modulated DSC for 4 polymorphs: FI(L), FI(H), FII, FV, and for the supercooled melt. The enthalpy of fusion of FII at its melting point has been estimated from the enthalpy of transition of FII into FI(H) through a thermodynamic cycle. Calorimetric data have been used to derive a quantitative polymorphic stability relationship between these 4 polymorphs, showing that FII is the stable polymorph below approximately 333 K, above which temperature FI(H) is the stable form up to its melting point. The relative stability of FV is well below the other polymorphs. The previously reported kinetic reversibility of the transformation between FI(L) and FI(H) has been verified using in situ Raman spectroscopy. The solid-liquid solubility of FII has been gravimetrically determined in 5 pure organic solvents (methanol, 1-propanol, ethyl acetate, acetonitrile, and toluene) over the temperature range 278 to 323 K. The ideal solubility has been estimated from calorimetric data, and solution activity coefficients at saturation in the 5 solvents determined. All solutions show positive deviation from Raoult's law, and all van't Hoff plots of solubility data are nonlinear. The solubility in toluene is well below that observed in the other investigated solvents. Solubility data have been correlated and extrapolated to the melting point using a semiempirical regression model. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Water solubility of synthetic pyrope at high temperature and pressure up to 12GPa

NASA Astrophysics Data System (ADS)

Huang, S.; Chen, J.

2012-12-01

Water can be incorporated into normally anhydrous minerals as OH- defects and transported into the mantle. Its existence in the mantle may affect property of minerals, such as elasticity, electrical conductivity and rheological properties. As the secondary mineral in the mantle, garnet has not been extensively studied for its water solubility and there is discrepancies among the existing experiments on the water solubility in the garnet change at pressures and temperatures. Geiger et al., 1991 investigated water content in synthetic pyrope and concluded 0.02wt% to 0.07wt% OH- substitution. Lu et al., 1997 found 198ppm water in the Dora Miara pyrope at 100Kbar and 1000°C. Withers et al., 1998 claimed that water solubility in pyrope reached 1000ppm at 5GPa and then decreased as pressure increasing; above 7GPa, no water was detected. Mookherjee et al., 2009 also explored pyrope-rich garnet, which contains water up to 0.1%wt at 5-9GPa and temperatures 1373K-1473K. Here we report a study of water solubility of synthetic single crystal pyrope at pressures 4-12GPa and temperature 1000°C. Single crystals of pyrope were synthesized using multi-anvil press and water contents in these samples were measured using FTIR. We have observed OH- peak at 3650 cm-1 along this pressure range, although Withers, 1998 reported water contents decrease to undetectable level above 7GPa. Water solubility in pyrope will be reported as a function of pressure up to 12 GPa at 1000°C.

The influence of pressure on the activity coefficients of the solutes and on the solubility of minerals in the system Na-Ca-Cl-SO 4-H 2O to 200°C and 1 kbar and to high NaCl concentration

NASA Astrophysics Data System (ADS)

Monnin, Christophe

1990-12-01

A model is presented which is used to calculate the effect of pressure on activity coefficients of aqueous solutes in the system Na-Ca-Cl-SO 4-H 2O to 200°C. Literature data for the density and compressibility of aqueous binary solutions of Na 2SO 4 and CaCl 2 to 200°C are used to calculate the first and second pressure derivatives of Pitzer's ion interaction model parameters, as well as the standard molal compressibility and volume of these two salts. Empirical correlations between the apparent molal volume and compressibility of the aqueous electrolytes are used to guide the choice of the temperature dependent expressions used for the numerical representation of the derivatives of Pitzer's parameters with respect to pressure. For sodium sulfate solutions, such correlations are used to extrapolate compressibilities to 200°C. The change in the thermodynamic properties of the-CaSO 04 ion pair with pressure is taken into account by the variation of its dissociation constant. The volumetric properties (partial molal volumes and compressibilities) of multicomponent solutions in the Na-Ca-Cl-SO 4-H 2O system can be predicted from the information generated here and the volumetric equations of ROGERS and PITZER (1982) for NaCl. This model is then combined with the high temperature model of MOLLER (1988) of the same system in order to calculate activity coefficients at high pressures to 200°C. The resulting model is validated by comparing calculated and measured solubilities of anhydrite and gypsum in pure water and in NaCl solutions up to 6 M. The agreement between the calculated and measured solubilities of the calcium sulfates is typically better than 10% up to 200°C and 1 kbar. The relevance of temperature and pressure corrections to the activity coefficients of aqueous solutes is discussed in regard to the assumed accuracy with which geochemical models are able to calculate mineral solubilities.

A thermodynamic model for the prediction of phase equilibria and speciation in the H 2O-CO 2-NaCl-CaCO 3-CaSO 4 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to halite saturation

NASA Astrophysics Data System (ADS)

Li, Jun; Duan, Zhenhao

2011-08-01

A thermodynamic model is developed for the calculation of both phase and speciation equilibrium in the H 2O-CO 2-NaCl-CaCO 3-CaSO 4 system from 0 to 250 °C, and from 1 to 1000 bar with NaCl concentrations up to the saturation of halite. The vapor-liquid-solid (calcite, gypsum, anhydrite and halite) equilibrium together with the chemical equilibrium of H+,Na+,Ca, CaHCO3+,Ca(OH)+,OH-,Cl-, HCO3-,HSO4-,SO42-, CO32-,CO,CaCO and CaSO 4(aq) in the aqueous liquid phase as a function of temperature, pressure and salt concentrations can be calculated with accuracy close to the experimental results. Based on this model validated from experimental data, it can be seen that temperature, pressure and salinity all have significant effects on pH, alkalinity and speciations of aqueous solutions and on the solubility of calcite, halite, anhydrite and gypsum. The solubility of anhydrite and gypsum will decrease as temperature increases (e.g. the solubility will decrease by 90% from 360 K to 460 K). The increase of pressure may increase the solubility of sulphate minerals (e.g. gypsum solubility increases by about 20-40% from vapor pressure to 600 bar). Addition of NaCl to the solution may increase mineral solubility up to about 3 molality of NaCl, adding more NaCl beyond that may slightly decrease its solubility. Dissolved CO 2 in solution may decrease the solubility of minerals. The influence of dissolved calcite on the solubility of gypsum and anhydrite can be ignored, but dissolved gypsum or anhydrite has a big influence on the calcite solubility. Online calculation is made available on www.geochem-model.org/model.

pH-Dependent Liquid-Liquid Phase Separation of Highly Supersaturated Solutions of Weakly Basic Drugs.

PubMed

Indulkar, Anura S; Box, Karl J; Taylor, Robert; Ruiz, Rebeca; Taylor, Lynne S

2015-07-06

Supersaturated solutions of poorly aqueous soluble drugs can be formed both in vivo and in vitro. For example, increases in pH during gastrointestinal transit can decrease the aqueous solubility of weakly basic drugs resulting in supersaturation, in particular when exiting the acidic stomach environment. Recently, it has been observed that highly supersaturated solutions of drugs with low aqueous solubility can undergo liquid-liquid phase separation (LLPS) prior to crystallization, forming a turbid solution such that the concentration of the drug in the continuous solution phase corresponds to the amorphous solubility while the colloidal phase is composed of a disordered drug-rich phase. Although it is well established that the equilibrium solubility of crystalline weakly basic drugs follows the Henderson-Hasselbalch relationship, the impact of pH on the LLPS phenomenon or the amorphous solubility has not been explored. In this work, the LLPS concentration of three weakly basic compounds-clotrimazole, nicardipine, and atazanavir-was determined as a function of pH using three different methods and was compared to the predicted amorphous solubility, which was calculated from the pH-dependent crystalline solubility and by estimating the free energy difference between the amorphous and crystalline forms. It was observed that, similar to crystalline solubility, the experimental amorphous solubility at any pH follows the Henderson-Hasselbalch relation and can be predicted if the amorphous solubility of the free base is known. Excellent agreement between the LLPS concentration and the predicted amorphous solubility was observed. Dissolution studies of amorphous drugs showed that the solution concentration can reach the corresponding LLPS concentration at that pH. Solid-state analysis of the precipitated material confirmed the amorphous nature. This work provides insight into the pH-dependent precipitation behavior of poorly water-soluble compounds and provides a fundamental basis with which to understand the performance of supersaturating dosage forms.

Magnetite solubility and phase stability in alkaline media at elevated temperatures

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

Ziemniak, S.E.; Jones, M.E.; Combs, K.E.S.

Magnetite, Fe{sub 3}O{sub 4}, is the dominant oxide constituent of the indigenous corrosion layers that form on iron base alloys in high purity, high temperature water. The apparent simultaneous stability of two distinct oxidation states of iron in this metal oxide is responsible for its unique solubility behavior. The present work was undertaken to extend the experimental and theoretical bases for estimating solubilities of an iron corrosion product (Fe{sub 3}O{sub 4}/Fe(OH){sub 2}) over a broader temperature range and in the presence of complexing, pH-controlling reagents. These results indicate that a surface layer of ferrous hydroxide controls magnetite solubility behavior atmore » low temperatures in much the same manner as a surface layer of nickel(II) hydroxide was previously reported to control the low temperature solubility behavior of NiO. The importance of Fe(III) ion complexes implies not only that most previously-derived thermodynamic properties of the Fe(OH){sub 3}{sup {minus}} ion are incorrect, but that magnetite phase stability probably shifts to favor a sodium ferric hydroxyphosphate compound in alkaline sodium phosphate solutions at elevated temperatures. The test methodology involved pumping alkaline solutions of known composition through a bed of Fe{sub 3}O{sub 4} granules and analyzing the emerging solution for Fe. Two pH-controlling reagents were tested: sodium phosphate and ammonia. Equilibria for the following reactions were described in thermodynamic terms: (a) Fe(OH){sub 2}/Fe{sub 3}O{sub 4} dissolution and transformation, (b) Fe(II) and Fe(III) ion hydroxocomplex formation (hydrolysis), (c) Fe(II) ion amminocomplex formation, and (d) Fe(II) and Fe(III) ion phosphatocomplex formation. 36 refs.« less

Geochemical Modeling of Zinc Silicate Ore Formation from Sedimentary Hydrothermal Fluids

NASA Astrophysics Data System (ADS)

Appold, M. S.

2008-12-01

Sediment-hosted zinc deposits dominated by willemite (Zn2SiO4) instead of sphalerite (ZnS) are known from several prominent occurrences worldwide, including Vazante, Brazil, the Aroona Trend, Australia, Kabwe, Zambia, Berg Aukas, Namibia, and Abu Samar, Sudan. Although willemite-dominant zinc deposits appear to be much less common and are on average smaller than sphalerite-dominant zinc deposits, they nonetheless represent major enrichments of zinc in the Earth's crust, reaching sizes on the order of 1's to 10's of millions of tons and grades commonly between 20 and 40%. Sediment-hosted willemite- and sphalerite-dominant deposits share many similarities including their predominantly carbonate host rocks, gangue mineralogy, presumed derivation from sedimentary basinal brines, and spatial proximity. However, the conditions and processes that led to one style of mineralization versus the other have only recently begun to be investigated. The current study presents solubility, reaction path, and reactive transport modeling results that attempt to define more clearly the conditions that favor willemite ore formation in sedimentary basins, with a focus on the Vazante deposit. Solubility calculations for willemite and sphalerite as a function of temperature, pH, salinity, and oxidation potential were carried out using a simple 3 molal NaCl solution saturated with respect to quartz. The results show that (1) willemite solubility is relatively insensitive to changes in temperature and oxidation potential whereas sphalerite solubility decreases sharply with decreasing temperature and oxidation potential, (2) willemite solubility decreases more strongly than sphalerite with increasing pH, (3) willemite and sphalerite have a similar strong decrease in solubility with decreasing salinity. The results support a previously proposed genetic model for a willemite-dominant, sphalerite-subordinate ore body like Vazante in which a hot, acidic, metal-rich ore fluid mixed with a cooler, more oxidizing, dilute, and basic fluid. This scenario was investigated further with reaction path and reactive transport modeling. In these models, a more complex ore fluid was used that was assumed to have a major element composition similar to the global average for Mississippi Valley-type (MVT) deposits determined from the literature, modified by heating from 150 to 300° C, saturated with respect to dolomite and quartz, moderately acidic, and an oxidation potential near the value defined by magnetite-hematite equilibrium. The ore fluid was allowed to mix with a second, possibly meteoric fluid with about three orders of magnitude lower salinity, neutral pH, and a temperature of 50° C. The modeling results showed general agreement with the mineral assemblage observed at Vazante, and confirmed the need for a strong pH increase to induce willemite precipitation, and no more than a moderate increase in oxidation potential to allow some sphalerite to precipitate. The localization of mineralization within a shear zone was found to depend strongly on the shear zone having acted as a high permeability conduit for the ore fluid from deeper parts of the sedimentary basin.

Solubility of non-polar gases in electrolyte solutions

NASA Technical Reports Server (NTRS)

Walker, R. L., Jr.

1970-01-01

Solubility theory describes the effects of both concentration and temperature on solute activity coefficients. It predicts the salting-out effect and the decrease in solubility of non-polar gases with increased electrolyte concentration, and can be used to calculate heats of solution, entropies, and partial molal volumes of dissolved gases

Effect of CO2 Solubility on Dissolution Rates of Minerals in Porous Media Imbibed with Brine: Actual Efficiency of CO2 Sequestration

NASA Astrophysics Data System (ADS)

Alizadeh Nomeli, M.; Riaz, A.

2016-12-01

A new model is developed for geochemical reactions to access dissolution rate of minerals in saline aquifers with respect to saturated concentration of dissolved CO2 as a function of parameters that are dynamically available during computer program execution such as pressure, temperature, and salinity. A general Arrhenius-type equation, with an explicit dependence on the pH of brine, is employed to determine the rates of mineral dissolution. The amount of dissolved CO2 is determined with the help of an accurate PVTx model for the temperature range of 50-100C and pressures up to 600 bar relevant to the geologic sequestration of CO2. We show how activity coefficients for a given salinity condition alters solubility, pH, and reaction rates. We further evaluate the significance of the pre-exponential factor and the reaction order associated with the modified Arrhenius equation to determine the sensitivity of the reaction rates as a function to the pH of the system. It is found that the model can reasonably reproduce experimental data with new parameters that we obtain from sensitivity studies. Using the new rate equation, we investigate geochemically induced alterations of fracture geometry due to mineral dissolution. Finally, we use our model to evaluate the effects of temperature, pressure, and salinity on the actual efficiency of CO2 storage.

Formation of a bioconjugate composed of hemin, smectite, and quaternary ammonium chloride that is soluble and active in hydrophobic media.

PubMed

Kurosawa, Masaru; Itoh, Tetsuji; Kodera, Yoh; Matsushima, Ayako; Hiroto, Misao; Nishimura, Hiroyuki; Inada, Yuji

2002-01-01

Hemin (Fe(3+)) was adsorbed onto synthetic smectite (clay mineral) intercalated with a quaternary alkenylammonium compound, dioleyldimethylammonium chloride (DOA), to form a hemin-smectite-DOA conjugate. The hemin-smectite-DOA conjugate was soluble in organic solvents such as benzene and toluene to form a transparent colloidal solution with a light yellow color. Its absorption spectrum in benzene showed two bands, 600 and 568 nm, in the visible region and a sharp Soret band at 400 nm with the molar extinction coefficient of 7.5 x 10(4) M(-1) cm(-1). The formation of the conjugate of smectite and DOA was confirmed by X-ray diffraction analysis: the basal spacing, d(001), of hemin-smectite-DOA conjugate was 19 A which is an expansion of the interlayer space by 5 A based upon the basal spacing of smectite of 14 A. Hemin-smectite-DOA conjugate catalyzed the peroxidase-like reaction in organic solvents using benzoyl peroxide as the hydrogen acceptor and leucocrystal violet as the hydrogen donor. The temperature-dependent peroxidase-like activity of the conjugate was compared with peroxidase activity of horseradish peroxidase. The hemin-smectite-DOA conjugate exhibited higher activity as the temperature was increased from 30 to 70 degrees C, while horseradish peroxidase activity was reduced as the temperature was increased.

Thermodynamic Equilibrium Solubility of Diethanolamine – N-Butyl-1-Methylpyrrolidinium Dicyanamide [DEABMPYRR DCA] Mixtures for Carbon Dioxide Capture

NASA Astrophysics Data System (ADS)

Salleh, R. M.; Jamaludin, S. N.

2018-05-01

Solubility data of carbon dioxide (CO2) in aqueous Diethanolamine (DEA) blended with pyrrolidinium-based ionic liquid: N-Butyl-1-Methylpyrrolidinium Dıcyanamıde [Bmpyrr][DCA] are presented at various temperatures (313.15K-333.15K) and pressure up to about 700 psi. The concentration of [Bmpyrr][DCA] ranges from 0-10wt% and 30-40wt% for DEA. The solubility of CO2 was evaluated by measuring the pressure drop in high pressure stirred absorption cell reactor. The CO2 loading in all studied mixtures increases with an increase in CO2 partial pressure and decreases with temperature. It was also found that the CO2 loading capacity decrease as the concentration of [Bmpyrr][DCA] increases. The experimental data were correlated as a function of temperature and CO2 partial pressure to predict the solubility of CO2 in the mixtures. It was found that the model predicted results in a good agreement with experimental value.

Summary Abstract: Growth and Alloying of Pd Films on Mo(110) Surfaces

NASA Technical Reports Server (NTRS)

Park, Ch. E.; Poppa, H.; Bauer, E.

1985-01-01

Alloying in small metal particles and in very thin films has recently received considerable attention. In the past it has been generally assumed that alloying is insignificant up to temperatures. Thus many epitaxy experiments of metals on metals with complete miscibility were performed at temperatures between 200 and 400 C and analyzed assuming no alloying. In particular, alloying was not suspected if the film material was not soluble in the substrate. In the present study, which was stimulated by annealing-induced CO adsorption anomalies on thin film surfaces, it has become evident that low temperature alloying can occur in thin films on a metal substrate which is refractory and has very strong interatomic bonds (as evidenced by a high sublimation energy) provided that the substrate is soluble in the film material. A good example of such a film-substrate combination is Pd on Mo. The solubility of Pd in Mo is very at temperatures below 1000 K but Pd can dissolve slightly more than 40 at. % Mo even at low temperatures.

Active thermal fine laser tuning in a broad spectral range and optical properties of cholesteric liquid crystal.

PubMed

Jeong, Mi-Yun; Kwak, Keumcheol

2016-11-20

In this study, we achieved active fine laser tuning in a broad spectral range with dye-doped cholesteric liquid crystal wedge-type cells through temperature control. The spatial pitch gradient of each position of the wedge cell at room temperature was almost maintained after developing a temperature gradient. To achieve the maximum tuning range, the chiral dopant concentration, thickness, thickness gradient, and temperature gradient on the wedge cell should be matched properly. In order to understand the laser tuning mechanism for temperature change, we studied the temperature dependence of optical properties of the photonic bandgap of cholesteric liquid crystals. In our cholesteric liquid crystal samples, when temperature was increased, photonic bandgaps were shifted toward blue, while the width of the photonic bandgap was decreased, regardless of whether the helicity was left-handed or right-handed. This is mainly due to the combination of decreased refractive indices, higher molecular anisotropy of chiral molecules, and increased chiral molecular solubility. We envisage that this kind of study will prove useful in the development of practical active tunable CLC laser devices.

The solubility of platinum in silicate melt under reducing conditions: Results from experiments without metal inclusions

NASA Astrophysics Data System (ADS)

Bennett, N. R.; Brenan, J. M.; Koga, K. T.

2014-05-01

The solubility of Pt in silicate melt was investigated at conditions of 2073-2573 K, 2 GPa and ˜IW -1.5 to +3.5. These are the first measurements of Pt solubility under conditions more reducing than the iron-wüstite buffer (IW) which are demonstrably free from contamination by metal-inclusions. Pt solubility increases with increasing temperature and decreasing oxygen fugacity. The ability of carbon to enhance Pt solubility under reducing conditions (3500 K. Under these conditions however, the estimated Pt/Os ratio is ˜40,000 times higher than that estimated for the PUM (Brandon et al., 2006). Instead, the PUM composition is generated most readily by metal-silicate equilibrium at more modest temperatures (˜3100 K), followed by a late accretion of chondritic material subsequent to core formation.

High pressure solubility of carbon dioxide (CO2) in aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) solvent for CO2 capture

NASA Astrophysics Data System (ADS)

Khan, Saleem Nawaz; Hailegiorgis, Sintayehu Mekuria; Man, Zakaria; Shariff, Azmi Mohd

2017-10-01

In this study, the solubility of carbon dioxide (CO2) in the aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) was investigated. In the aqueous solution the concentrations of the N-methyldiethanolamine (MDEA) and piperazine (PZ) were kept constant at 30 wt. % and 3 wt. %, respectively. The solubility experiments were carried out between the temperatures ranges of 303.15 to 333.15 K. The pressure range was selected as 2-50 bar for solubility of carbon dioxide in the aqueous solution. The solubility of the CO2 is reported in terms of CO2 loading capacity of the solvent. The loading capacity of the solvent is the ratio between the numbers of moles of CO2 absorbed to the numbers of moles of solvent used. The experimental data showed that the CO2 loading increased with increase in CO2 partial pressure, while it decreased with increase in system's temperature. It was also observed from the experimental data that the higher pressure favors the absorption process while the increased temperature hinders the absorption process of CO2 capture. The loading capacity of the investigated solvent was compared with the loading capacity of the solvents reported in the literature. The investigated solvent showed better solubility in terms of loading capacity.

The presence of functional groups key for biodegradation in ionic liquids: effect on gas solubility.

PubMed

Deng, Yun; Morrissey, Saibh; Gathergood, Nicholas; Delort, Anne-Marie; Husson, Pascale; Costa Gomes, Margarida F

2010-03-22

The effect of the incorporation of either ester or ester and ether functions into the side chain of an 1-alkyl-3-methylimidazolium cation on the physico-chemical properties of ionic liquids containing bis(trifluoromethylsulfonyl)imide or octylsulfate anions is studied. It is believed that the introduction of an ester function into the cation of the ionic liquids greatly increases their biodegradability. The density of three such ionic liquids is measured as a function of temperature, and the solubility of four gases-carbon dioxide, ethane, methane, and hydrogen-is determined between 303 K and 343 K and at pressures close to atmospheric level. Carbon dioxide is the most soluble gas, followed by ethane and methane; the mole fraction solubilities vary from 1.8 x 10(-3) to 3.7 x 10(-2). These solubilities are of the same order of magnitude as those determined for alkylimidazolium-based ionic liquids. The chemical modification of the alkyl side chain does not result in a significant change of the solvation properties of the ionic liquid. All of the solubilities decrease with increasing temperature, corresponding to an exothermal solvation process. From the variation of this property with temperature, the thermodynamic functions of solvation (Gibbs energy, enthalpy, and entropy) are calculated and provide information about the solute-solvent interactions and the molecular structure of the solutions.

Investigation on solubility of hydroxy dibasic acids in alkanolamine solutions

NASA Astrophysics Data System (ADS)

Du, M.

2017-12-01

Solubilities of three hydroxy dibasic (adipic, suberic, and sebacic) acids in alkanolamine solutions were measured within the 30-90℃ temperature range. It is found that solubility of these acids sharply grows with temperature and concentration of alkanolamine solvent. In addition, the study substantiates the adjustment of pH to optimize the CO2 absorption and desorption processes. The precipitation of added acids from alkanolamine solvents by cooling is found to be quite problematic, which makes the recovery of residual acids from lean alkanolamine solvents non-feasible and requires the application of alternative methods.

The solubility of the noble gases He, Ne, Ar, Kr, and Xe in water up to the critical point

USGS Publications Warehouse

Potter, R.W.; Clynne, M.A.

1978-01-01

The solubility of the noble gases Ar, He, Ne, Kr, and Xe in pure water was measured from 298 to 561??K. These data in turn were extrapolated to the critical point of water, thus providing a complete set of Henry's law constants from 274 to 647??K when combined with the existing literature data. Equations describing the behavior of the Henry's law constants over this temperature range are also given. The data do not confirm extrapolations of empirical correlations based on low-temperature solubility data. ?? 1978 Plenum Publishing Corporation.

Estimating the Aqueous Solubility of Pharmaceutical Hydrates.

PubMed

Franklin, Stephen J; Younis, Usir S; Myrdal, Paul B

2016-06-01

Estimation of crystalline solute solubility is well documented throughout the literature. However, the anhydrous crystal form is typically considered with these models, which is not always the most stable crystal form in water. In this study, an equation which predicts the aqueous solubility of a hydrate is presented. This research attempts to extend the utility of the ideal solubility equation by incorporating desolvation energetics of the hydrated crystal. Similar to the ideal solubility equation, which accounts for the energetics of melting, this model approximates the energy of dehydration to the entropy of vaporization for water. Aqueous solubilities, dehydration and melting temperatures, and log P values were collected experimentally and from the literature. The data set includes different hydrate types and a range of log P values. Three models are evaluated, the most accurate model approximates the entropy of dehydration (ΔSd) by the entropy of vaporization (ΔSvap) for water, and utilizes onset dehydration and melting temperatures in combination with log P. With this model, the average absolute error for the prediction of solubility of 14 compounds was 0.32 log units. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Recrystallization of water in non-water-soluble (meth)acrylate polymers is not rare and is not devitrification.

PubMed

Gemmei-Ide, Makoto; Ohya, Atsushi; Kitano, Hiromi

2012-02-16

Change in the state of water sorbed into four kinds of non-water-soluble poly(meth)acrylates with low water content by temperature (T) perturbation was examined on the basis of T variable mid-infrared (MIR) spectroscopy. Many studies using differential scanning calorimetry suggested that there was no change in the state. T dependence of their MIR spectra, however, clearly demonstrated various changes in the state. Furthermore, recrystallization, which was crystallization during heating, was observed in all four polymers. The recrystallization observed in this study was not devitrification, which is the change in the state from glassy water to crystalline water, but vapor deposition during heating (vapor re-deposition). There were only two reports about recrystallization of water in a non-water-soluble polymer before this report; therefore, it might be considered to be a rare phenomenon. However, as demonstrated in this study, it is not a rare phenomenon. Recrystallization (vapor re-deposition) of water in the polymer matrices is related to a balance between flexibility and strength of the electrostatic interaction sites of polymer matrices but might not be related to the biocompatibility of polymers.

A Thermodynamic Approach for Modeling H2O-CO2 Solubility in Alkali-rich Mafic Magmas at Mid-crustal Pressures

NASA Astrophysics Data System (ADS)

Allison, C. M.; Roggensack, K.; Clarke, A. B.

2017-12-01

Volatile solubility in magmas is dependent on several factors, including composition and pressure. Mafic (basaltic) magmas with high concentrations of alkali elements (Na and K) are capable of dissolving larger quantities of H2O and CO2 than low-alkali basalt. The exsolution of abundant gases dissolved in alkali-rich mafic magmas can contribute to large explosive eruptions. Existing volatile solubility models for alkali-rich mafic magmas are well calibrated below 200 MPa, but at greater pressures the experimental data is sparse. To allow for accurate interpretation of mafic magmatic systems at higher pressures, we conducted a set of mixed H2O-CO2 volatile solubility experiments between 400 and 600 MPa at 1200 °C in six mafic compositions with variable alkali contents. Compositions include magmas from volcanoes in Italy, Antarctica, and Arizona. Results from our experiments indicate that existing volatile solubility models for alkali-rich mafic magmas, if extrapolated beyond their calibrated range, over-predict CO2 solubility at mid-crustal pressures. Physically, these results suggest that volatile exsolution can occur at deeper levels than what can be resolved from the lower-pressure experimental data. Existing thermodynamic models used to calculate volatile solubility at different pressures require two experimentally derived parameters. These parameters represent the partial molar volume of the condensed volatile species in the melt and its equilibrium constant, both calculated at a standard temperature and pressure. We derived these parameters for each studied composition and the corresponding thermodynamic model shows good agreement with the CO2 solubility data of the experiments. A general alkali basalt solubility model was also constructed by establishing a relationship between magma composition and the thermodynamic parameters. We utilize cation fractions from our six compositions along with four compositions from the experimental literature in a linear regression to generate this compositional relationship. Our revised general model provides a new framework to interpret volcanic data, yielding greater depths for melt inclusion entrapment than previously calculated using other models, and it can be applied to mafic magma compositions for which no experimental data is available.

AW-101 entrained solids - Solubility versus temperature

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

GJ Lumetta; RC Lettau; GF Piepel

This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AW-101 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AW-1-1 sample using de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AW-101 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions. The work was conducted according to test plan BNFL-TP-29953-7, Rev. 0, Determinationmore » of the Solubility of LAW Entrained Solids. The test went according to plan, with no deviations from the test plan.« less

In vitro characterization of a novel polymeric system for preparation of amorphous solid drug dispersions.

PubMed

Mahmoudi, Zahra N; Upadhye, Sampada B; Ferrizzi, David; Rajabi-Siahboomi, Ali R

2014-07-01

Preparation of amorphous solid dispersions using polymers is a commonly used formulation strategy for enhancing the solubility of poorly water-soluble drugs. However, often a single polymer may not bring about a significant enhancement in solubility or amorphous stability of a poorly water-soluble drug. This study describes application of a unique and novel binary polymeric blend in preparation of solid dispersions. The objective of this study was to investigate amorphous solid dispersions of glipizide, a BCS class II model drug, in a binary polymeric system of polyvinyl acetate phthalate (PVAP) and hypromellose (hydroxypropyl methylcellulose, HPMC). The solid dispersions were prepared using two different solvent methods: rotary evaporation (rotavap) and fluid bed drug layering on sugar spheres. The performance and physical stability of the dispersions were evaluated with non-sink dissolution testing, powder X-ray diffraction (PXRD), and modulated differential scanning calorimetry (mDSC). PXRD analysis demonstrated an amorphous state for glipizide, and mDSC showed no evidence of phase separation. Non-sink dissolution testing in pH 7.5 phosphate buffer indicated more than twofold increase in apparent solubility of the drug with PVAP-HPMC system. The glipizide solid dispersions demonstrated a high glass transition temperature (Tg) and acceptable chemical and physical stability during the stability period irrespective of the manufacturing process. In conclusion, the polymeric blend of PVAP-HPMC offers a unique formulation approach for developing amorphous solid dispersions with the flexibility towards the use of these polymers in different ratios and combined quantities depending on drug properties.

Poloxamer-Based Thermoreversible Gel for Topical Delivery of Emodin: Influence of P407 and P188 on Solubility of Emodin and Its Application in Cellular Activity Screening.

PubMed

Ban, Eunmi; Park, Mijung; Jeong, Seonghee; Kwon, Taekhyun; Kim, Eun-Hee; Jung, Kiwon; Kim, Aeri

2017-02-07

Emodin is a component in a Chinese herb, Rheum officinale Baill, traditionally used for diabetes and anticancer. Its poor solubility is one of the major challenges to pharmaceutical scientists. We previously reported on thermoreversible gel formulations based on poloxamer for the topical delivery of emodin. The present study was to understand the effect of poloxamer type on emodin solubility and its application in cellular activity screening. Various gel formulations composed of poloxamer 407 (P407), poloxamer 188 (P188) and PEG400 were prepared and evaluated. Major evaluation parameters were the gelation temperature (Tgel) and solubility of emodin. The emodin solubility increased with increasing poloxamer concentration and the Tgel was modulated by the proper combination of P407. In particular, this study showed that the amount of P407 in thermoreversible poloxamer gel (PG) was the dominant factor in enhancing solubility and P188 was effective at fixing gelation temperature in the desired range. A thermoreversible emodin PG was selected as the proper composition with the liquid state at room temperature and gel state at body temperature. The gel showed the solubility enhancement of emodin at least 100-fold compared to 10% ethanol or water. The thermoreversible formulation was applied for in vitro cellular activity screening in the human dermal fibroblast cell line and DLD-1 colon cancer cell line after dilution with cell culture media. The thermoreversible gel formulation remained as a clear solution in the microplate, which allowed reliable cellular activity screening. In contrast, emodin solution in ethanol or DMSO showed precipitation at the corresponding emodin concentration, complicating data interpretation. In conclusion, the gel formulation is proposed as a useful prototype topical formulation for testing emodin in vivo as well as in vitro.

A New Soluble Gelatin Sponge for Transcatheter Hepatic Arterial Embolization

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

Takasaka, Isao; Kawai, Nobuyuki; Sato, Morio, E-mail: morisato@mail.wakayama-med.ac.jp

2010-12-15

To prepare a soluble gelatin sponge (GS) and to explore the GS particles (GSPs) that inhibit development of collateral pathways when transcatheter hepatic arterial embolization is performed. The approval of the Institutional Committee on Research Animal Care of our institution was obtained. By means of 50 and 100 kDa of regenerative medicine-gelatin (RM-G), RM-G sponges were prepared by freeze-drying and heating to temperatures of 110-150{sup o}C for cross-linkage. The soluble times of RM-GSPs were measured in vitro. Eight swine for transcatheter hepatic arterial embolization were assigned into two groups: six received 135{sup o}C/50RM-GSPs, 125{sup o}C/100RM-GSPs, and 138{sup o}C/50RM-GSPs, with solublemore » time of 48 h or more in vitro; two swine received Gelpart GSPs (G-GSPs) with insoluble time of 14 days as a control. Transarterial chemoembolization was performed on two branches of the hepatic artery per swine. RM-GSPs heated at temperatures of 110-138{sup o}C were soluble. Mean soluble times of the RM-GSPs increased with higher temperature. Hepatic branches embolized with G-GSP remained occluded after 6 days, and development of collateral pathways was observed after 3 days. Hepatic branches embolized with 135{sup o}C/50RM-GSP and 125{sup o}C/100RM-GSP remained occluded for 4 h, and recanalization was observed after 1 day. Hepatic branches embolized with 138{sup o}C/50RM-GS remained occluded for 1 day, and recanalization was observed after 2 days with no development of collateral pathways. In RM-GSs with various soluble times that were prepared by modulating the heating temperature, 138{sup o}C/50RM-GSP was the soluble GSP with the longest occlusion time without inducing development of collateral pathways.« less

Novel method of niosome generation using supercritical carbon dioxide part I: process mechanics.

PubMed

Wagner, Michael E; Rizvi, Syed S H

2015-01-01

A novel method for the production of non-ionic surfactant vesicles (niosomes) using an rapid expansion of supercritical solution (RESS)-based process coupled with a gas ejector is presented along with an investigation of parameters affecting niosome morphology, size and encapsulation efficiency of a 0.2 M D-glucose solution in Tris buffer at physiological pH. The solubility of the non-ionic surfactant polyoxyethylene(4) sorbitan monostearate in SC-CO2 was determined at three pressures (10, 15 and 20 MPa) and three temperatures (40, 50 and 60 °C). Mole fraction of Tween61 in the vapor phase increased with pressure at 40 °C, but did not change with pressure at 50 or 60 °C. Solubility data were correlated using the Peng-Robinson equation of state (PREOS) with the Panagiotopoulos and Reid mixing rule. Vesicles were either multilamellar or unilamellar, depending on the degree of precipitation of the lipid formulation at the point of aqueous cargo introduction. Vesicle particle size distributions were bimodal, with the 80-99% of the liposomal volume contributed niosomes ranging in size from 3 to 7 μm and the remaining niosomes ranging from 239 to 969 nm, depending on the system configuration. Encapsulation efficiency as high as 28% using the gas ejector to introduce the glucose cargo solution was achieved. Vesicle particle size and encapsulation efficiency were shown to be dependent on cargo droplet formation.

Stability of cannabinoids in urine in three storage temperatures.

PubMed

Golding Fraga, S; Díaz-Flores Estévez, J; Díaz Romero, C

1998-01-01

Stability of cannabinoid compounds in urine samples were evaluated using several storage temperatures. Appreciable losses (> 22.4 percent) were observed in some urine samples, after being stored at room temperature for 10 days. Lower losses (8.1 percent) were observed when the urine samples were refrigerated for 4 weeks. The behavior of urine samples depended on the analyzed urine. This could be due to the different stability of the cannabinoids present in each urine sample. Important losses of 8.0 +/- 10.6, 15.8 +/- 4.2, and 19.6 +/- 6.7 percent were found when the urine samples were frozen during 40 days, 1 year, and 3 years, respectively. Average losses (> > 5 percent) can be observed after one day which could mainly be due to the decrease of the solubility of 11-nor-U9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) or adsorption process of cannabinoid molecules to the plastic storage containers.

Chemistry and adhesive properties of poly(arylene ether)s containing heterocyclic units

NASA Technical Reports Server (NTRS)

Connell, John W.

1991-01-01

Novel poly(arylene ether)s containing heterocyclic units were prepared, characterized, and evaluated as adhesives and composite matrices. The polymers were prepared by reacting a heterocyclic bisphenol with an activated aromatic dihalide in a polar aprotic solvent, using potassium carbonate. The polymerizations were generally carried out in N,N-dimethylacetamide at 155 C. In some cases, where the polymers were semicrystalline, higher temperatures and thus higher boiling solvents were necessary to keep the polymers in solution. Heterocyclic rings incorporated into the poly(arylene ether) backbone include phenylquinoxaline, phenylimidazole, benzimidazole, benzoxazole, 1,3,4-oxadiazole, and 1,2,4-triazole. The polymers were characterized by differential scanning calorimetry, solution viscosity, X-ray diffraction, thin film, and adhesive and (in some cases) composite properties. The glass transition temperatures, crystalline melt temperature, solubility, and mechanical properties varied depending upon the heterocyclic ring. The chemistry and properties of these materials are discussed.

Low-temperature phase transitions in a soluble oligoacene and their effect on device performance and stability

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

Ward, J. W.; Goetz, K. P.; Obaid, A.

The use of organic semiconductors in high-performance organic field-effect transistors requires a thorough understanding of the effects that processing conditions, thermal, and bias-stress history have on device operation. Here, we evaluate the temperature dependence of the electrical properties of transistors fabricated with 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene, a material that has attracted much attention recently due to its exceptional electrical properties. We have discovered a phase transition at T = 205 K and discuss its implications on device performance and stability. We examined the impact of this low-temperature phase transition on the thermodynamic, electrical, and structural properties of both single crystals and thin films of this material.more » Our results show that while the changes to the crystal structure are reversible, the induced thermal stress yields irreversible degradation of the devices.« less

Ecotoxicological characterization of biochars: role of feedstock and pyrolysis temperature.

PubMed

Domene, X; Enders, A; Hanley, K; Lehmann, J

2015-04-15

Seven contrasting feedstocks were subjected to slow pyrolysis at low (300 or 350°C) and high temperature (550 or 600°C), and both biochars and the corresponding feedstocks tested for short-term ecotoxicity using basal soil respiration and collembolan reproduction tests. After a 28-d incubation, soil basal respiration was not inhibited but stimulated by additions of feedstocks and biochars. However, variation in soil respiration was dependent on both feedstock and pyrolysis temperature. In the last case, respiration decreased with pyrolysis temperature (r=-0.78; p<0.0001, n=21) and increased with a higher volatile matter content (r=0.51; p<0.017), these two variables being correlated (r=-0.86, p<0.0001). Collembolan reproduction was generally unaffected by any of the additions, but when inhibited, it was mostly influenced by feedstock, and generally without any influence of charring itself and pyrolysis temperature. Strong inhibition was only observed in uncharred food waste and resulting biochars. Inhibition effects were probably linked to high soluble Na and NH4 concentrations when both feedstocks and biochars were considered, but mostly to soluble Na when only biochars were taken into account. The general lack of toxicity of the set of slow pyrolysis biochars in this study at typical field application rates (≤20 Mg ha(-1)) suggests a low short-term toxicity risk. At higher application rates (20-540 Mg ha(-1)), some biochars affected collembolan reproduction to some extent, but only strongly in the food waste biochars. Such negative impacts were not anticipated by the criteria set in currently available biochar quality standards, pointing out the need to consider ecotoxicological criteria either explicitly or implicitly in biochar characterization schemes or in management recommendations. Copyright © 2014 Elsevier B.V. All rights reserved.

Injectable biodegradable temperature-responsive PLGA-PEG-PLGA copolymers: synthesis and effect of copolymer composition on the drug release from the copolymer-based hydrogels.

PubMed

Qiao, Mingxi; Chen, Dawei; Ma, Xichen; Liu, Yanjun

2005-04-27

Injectable biodegradable temperature-responsive poly(DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers with DL-lactide/glycolide molar ratio ranging from 6/1 to 15/l were synthesized from monomers of DL-lactide, glycolide and polyethylene glycol and characterized by 1H NMR. The resulting copolymers are soluble in water to form free flowing fluid at room temperature but become hydrogels at body temperature. The hydrophobicity of the copolymer increased with the increasing of DL-lactide/glycolide molar ratio. In vitro dissolution studies with two different hydrophobic drugs (5-fluorouracil and indomethacin) were performed to study the effect of DL-lactide/glycolide molar ratio on drug release and to elucidate drug release mechanism. The release mechanism for hydrophilic 5-fluorouracil was diffusion-controlled, while hydrophobic indomethacin showed an biphasic profile comprising of an initial diffusion-controlled stage followed by the hydrogel erosion-dominated stage. The effect of DL-lactide/glycolide molar ratio on drug release seemed to be dependent on the drug release mechanism. It has less effect on the drug release during the diffusion-controlled stage, but significantly affected drug release during the hydrogel erosion-controlled stage. Compared with ReGel system, the synthesized copolymers showed a higher gelation temperature and longer period of drug release. The copolymers can solubilize the hydrophobic indomethacin and the solubility (13.7 mg/ml) was increased 3425-fold compared to that in water (4 microg/ml, 25 degrees C). Two methods of physical mixing method and solvent evaporation method were used for drug solubilization and the latter method showed higher solubilization efficiency.

Investigation on drug solubility enhancement using deep eutectic solvents and their derivatives.

PubMed

Li, Zheng; Lee, Ping I

2016-05-30

Deep eutectic solvent (DES) is a room temperature liquid typically formed by mixing two solid compounds, such as a quaternary ammonium salt (QAS) (e.g. choline chloride) and a hydrogen bond donor (HBD) (e.g. urea or a carboxylic acid) at their eutectic composition. Very often, a range of room temperature liquids can also be obtained near the eutectic composition. Hence, it is more convenient to introduce a more general term deep eutectic solvent derivatives (DESDs) to describe a wide range of DES-like derivatives including those derived from ternary mixtures. The melting point of the mixture is lowered because the hydrogen bonding between DESD components reduces the lattice energy of components of the eutectic system. Based on the analysis of available data for 22 such choline chloride-based DES pairs, we found that the observed melting point depression can be statistically correlated with the difference between the hydrogen bonding contribution (δh) and the polar contribution (δp) to the solubility parameter of the hydrogen bond donor (HBD) component. The correlation was validated with a new DESD based on glycolic acid and choline chloride, which form DESDs at a molar ratio between 1:1 and 1:4 with DES-like properties. As a room temperature liquid, this DESD exhibits a wide range of solubility enhancement on several weakly basic poorly water-soluble drugs. For example, the solubility of itraconazole, piroxicam, lidocaine, and posaconazole has been observed to increase by 6700, 430, 28, and 6400-fold, respectively as compared to their aqueous solubility at room temperature. Furthermore, another new ternary DESD based on choline chloride, glycolic acid, and oxalic acid at a molar ratio of 1:1.6:0.4 is shown to further increase the solubility of itraconazole to a remarkable level of 5.36mg/mL (a 53,600-fold increase!). Because the components of such DESDs can include those biodegradable ones that had previously been used in formulated human products, the potential applicability of suitable DESDs to drug delivery, especially in enhancing drug solubility for topical formulations could be very attractive. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of storage conditions on the solubility and viscosity of β-glucan extracted from bread under in vitro conditions.

PubMed

Moriartey, Stephanie; Temelli, Feral; Vasanthan, Thava

2011-01-01

The viscosity and solubility of β-glucan in muffins have been shown to be reduced by certain storage conditions, though the effect of storage on bread fortified with barley β-glucan concentrate has not been investigated. Therefore, this study investigated the effect of storage temperature and time (23 °C for 1, 4, and 7 d, 4 °C for 4, 7, and 14 d, and -20 °C for 1, 2, 4, and 8 wk) on the solubility and viscosity of β-glucan upon incorporation into bread at levels corresponding to 0 or 1.5 g β-glucan/serving, with or without vital gluten addition. The firmness and moisture content of bread following each storage treatment were also evaluated. The highest moisture and lowest firmness values were found in fresh bread, though these parameters were still maintained at appreciable levels upon room temperature storage of the 1.5 g β-glucan/serving bread with added gluten and at either room temperature or frozen storage for the 1.5 g β-glucan/serving bread for 4 d. If it is desirable to store bread for 7 d or more, frozen storage should be utilized in order to best maintain bread moisture and firmness levels. It is recommended that β-glucan-fortified bread be consumed fresh for greatest β-glucan solubility and viscosity, though β-glucan solubility of approximately 40% is still achievable upon frozen storage of the bread for up to 2 wk. It is still unclear, however, as to what extent of reductions in the solubility and viscosity of β-glucan would lower its physiological effectiveness. Previous research has demonstrated that solubility and thus viscosity of β-glucan, which is an important property associated with its health benefits can be impacted by different storage conditions applied to some bakery products, like muffins. This study demonstrates the extent of changes in the solubility and viscosity of β-glucan incorporated into bread. Therefore, storage time and temperature should be optimized to minimize changes in β-glucan for maintaining its efficacy for its health benefits.

Characterization of the surface tension and solubility parameter of epoxy resin by using inverse gas chromatography.

PubMed

Shi, Fenghui; Dai, Zhishuang; Zhang, Baoyan

2010-07-01

Inverse gas chromatography (IGC) was used to measure the surface tension and solubility parameter of E51 epoxy resin in this work. By using the Schultz method, decane, nonane, octane and heptane were chosen as the neutral probes to calculate the dispersive surface tensions (gamma(D)). Based on the Good-van Oss equation, the specific surface tension (gamma(SP)) of E51 epoxy resin was calculated with the acidic probe of dichloromethane and the basic probe of toluene. The results showed that the gamma(D) and gamma(SP) of the E51 resin decreased linearly with the increase of temperature. According to the Flory-Huggins parameters (chi) between the resin and a series of probes, the solubility parameters (delta) of E51 resin at different temperatures were estimated using the method developed by DiPaola-Baranyi and Guillet. It was found that the values of delta of the E51 resin were 11.78, 11.57, 11.48 and 11.14 MPa1/2 at 30, 40, 50 and 60 degrees C, respectively. The dispersive component (delta(D)) and the specific component (delta(SP)) of solubility parameter at different temperatures of the E51 resin were investigated according to the relationships between surface tension, cohesion energy and solubility parameter. The results showed that the values of delta(D) were higher than those of delta(SP) for the epoxy resin, and both of them decreased with the increase of temperature.

A method of calculating quartz solubilities in aqueous sodium chloride solutions

USGS Publications Warehouse

Fournier, R.O.

1983-01-01

The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles) per 1,000 cm3 of solution allows activity of water in a NaCl solution at high temperature to be closely approximated by the effective density of water, pe, in that solution, i.e. the product of the density of the NaCl solution times the weight fraction of water in the solution, corrected for the amount of water strongly bound to aqueous silica and Na+ as water of hydration. Generally, the hydration of water correction is negligible. The solubility of quartz in pure water is well known over a large temperature-pressure range. An empirical formula expresses that solubility in terms of temperature and density of water and thus takes care of activity coefficient and pressure-effect terms. Solubilities of quartz in NaCl solutions can be calculated by using that equation and substituting pe, for the density of pure water. Calculated and experimentally determined quartz solubilities in NaCl solutions show excellent agreement when the experiments were carried out in non-reactive platinum, gold, or gold plus titanium containers. Reactive metal containers generally yield dissolved silica concentrations higher than calculated, probably because of the formation of metal chlorides plus NaOH and H2. In the absence of NaOH there appears to be no detectable silica complexing in NaCl solutions, and the variation in quartz solubility with NaCl concentration at constant temperature can be accounted for entirely by variations in the activity of water. The average hydration number per molecule of dissolved SiO2 in liquid water and NaCl solutions decreases from about 2.4 at 200??C to about 2.1 at 350??C. This suggests that H4SiO4 may be the dominant aqueous silica species at 350??C, but other polymeric forms become important at lower temperatures. ?? 1983.

Waterborne Electrospinning of Poly(N-isopropylacrylamide) by Control of Environmental Parameters.

PubMed

Schoolaert, Ella; Ryckx, Paulien; Geltmeyer, Jozefien; Maji, Samarendra; Van Steenberge, Paul H M; D'hooge, Dagmar R; Hoogenboom, Richard; De Clerck, Karen

2017-07-19

With increasing toxicity and environmental concerns, electrospinning from water, i.e., waterborne electrospinning, is crucial to further exploit the resulting nanofiber potential. Most water-soluble polymers have the inherent limitation of resulting in water-soluble nanofibers, and a tedious chemical cross-linking step is required to reach stable nanofibers. An interesting alternative route is the use of thermoresponsive polymers, such as poly(N-isopropylacrylamide) (PNIPAM), as they are water-soluble beneath their lower critical solution temperature (LCST) allowing low-temperature electrospinning while the obtained nanofibers are water-stable above the LCST. Moreover, PNIPAM nanofibers show major potential to many application fields, including biomedicine, as they combine the well-known on-off switching behavior of PNIPAM, thanks to its LCST, with the unique properties of nanofibers. In the present work, based on dedicated turbidity and rheological measurements, optimal combinations of polymer concentration, environmental temperature, and relative humidity are identified allowing, for the first time, the production of continuous, bead-free PNIPAM nanofibers electrospun from water. More specifically, PNIPAM gelation was found to occur well below its LCST at higher polymer concentrations leading to a temperature regime where the viscosity significantly increases without compromising the polymer solubility. This opens up the ecological, water-based production of uniform PNIPAM nanofibers that are stable in water at temperatures above PNIPAM's LCST, making them suitable for various applications, including drug delivery and switchable cell culture substrates.

Experimental measurement and thermodynamic modeling of the solubility of carbon dioxide in aqueous blends of monoethanolamine and diethanolamine

NASA Astrophysics Data System (ADS)

Suleman, Humbul; Maulud, Abdulhalim Shah; Man, Zakaria

2017-12-01

In this study, the solubilities of carbon dioxide in aqueous mixtures of monoethanolamine (MEA) and diethanolamine (DEA) were determined using a high pressure vapor-liquid equilibrium apparatus. The carbon dioxide loadings (mole of CO2/mole of amine mixture) were reported for a wide range of temperature (303.15, 323.15, 343.15 K) and pressure (100 - 4100 kPa). The carbon dioxide solubility shows an increase with increase in pressure and amine concentration and a decrease with increase in temperature in the aqueous blends of MEA and DEA. At carbon dioxide loadings above 1.0, the carbon dioxide solubility becomes a weak function of pressure and follows the general trend of carbon dioxide solubility in aqueous alkanolamines. The new experimental data points determined in this study were correlated by using a recently developed, enhanced Kent-Eisenberg model. An average absolute relative error of 9.4 % was observed between the model results and experimental data, indicating good correlative capability of the thermodynamic model.

Correlation between ionic size and valence state of tetra, penta and hexavalent B-site substitution with solubility limit, phase transformation and multiferroic properties of Bi0.875Eu0.125FeO3

NASA Astrophysics Data System (ADS)

Mumtaz, Fiza; Jaffari, G. Hassnain; Hassan, Qadeer ul; Shah, S. Ismat

2018-06-01

We present detailed comparative study of effect of isovalent i.e. Eu+3 substitution at A-site and tetra (Ti+4, Zr+4), penta (V+5) and hexavalent (W+6) substitutions at B-site in BiFeO3. Eu+3 substitution led to phase transformation and exhibited mixed phases i.e. rhombohedral and orthorhombic, while tetravalent substituents (Ti+4 and Zr+4) led to stabilization of cubic phase. In higher valent (i.e. V+5 and W+6) cases solubility limit was significantly reduced where orthorhombic phase was observed as in the case of parent compound. Phase transformation as a consequence of increase in microstrain and chemical pressure induced by the substituent has been discussed. Solubility limit of different B-site dopants i.e. Zr, W and V was extracted to 5%, 2% and 2%, respectively. Extra phases in various cases were Bi2Fe4O9, Bi25FeO40, Bi14W2O27, and Bi23V4O44.5 and their fractional amount have been quantified. Ti was substituted up to 15% and has been observed to be completely soluble in the parent compound. Solubility limits depends on ionic radii mismatch and valance difference of Fe+3 and dopant, in which valance difference plays more dominant role. Solubility limit and phase transformation has been explained in terms of change in bond strength and tolerance factor induced by incorporation of dopant which depend on its size and valence state. Detail optical, dielectric, ferroelectric, magnetic and transport properties of Eu and Ti co-doped samples and selected low concentration B-site doped compositions (i.e. 2%) have presented and discussed. Two d-d transitions and three charge transfer transitions were observed within UV-VIS range. Both change in cell volume for the same phase and transformation in crystal structure affects the band gap. Increase in room temperature dielectric constant and saturation polarization was also found to increase in case of Eu-Ti co-doped samples with increasing concentration of Ti. Substitution of Eu at A-site and Ti at B-site led to observation of weak ferromagnetism. Effect of extra phases on ferroelectricity and transport properties have also been discussed.

Effects of heat treating PM Rene' 95 slightly below the gamma' solvus

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.

1977-01-01

An investigation was performed on as-hot-isostatically-pressed (As-HIP) Rene' 95 to obtain additional information on the variation of the amount of gamma prime with solutioning temperatures near the gamma prime solvus temperature and the resulting effects on tensile and stress rupture strength of As-HIP Rene' 95. The amount of gamma prime phase was found to increase at a rate of about 0.5% per degree Celsius as the temperature decreased from the solvus temperature to about 50 C below the gamma prime solvus temperature. The change in the amount of gamma prime phase with decreasing solutioning temperature was observed to be primarily associated with decreasing solubilities of Al+Ti+Nb and increasing solubility of Cr in the gamma phase.

Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress.

PubMed

Jia, Xia; Zhao, YongHua; Wang, WenKe; He, Yunhua

2015-09-23

The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and l-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings.

Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress

PubMed Central

Jia, Xia; Zhao, YongHua; Wang, WenKe; He, Yunhua

2015-01-01

The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and l-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings. PMID:26395070

Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress

NASA Astrophysics Data System (ADS)

Jia, Xia; Zhao, Yonghua; Wang, Wenke; He, Yunhua

2015-09-01

The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and L-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings.

Cr(III) solubility in aqueous fluids at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Watenphul, Anke; Schmidt, Christian; Jahn, Sandro

2014-02-01

Trivalent chromium is generally considered relatively insoluble in aqueous fluids and melts. However, numerous counterexamples in nature indicate Cr(III) mobilization by aqueous fluids during metamorphism or hydrothermal alteration of chromite-bearing rocks, or by pegmatite melts. So far, very little is known about the chromium concentrations and speciation in such fluids. In this study, the solubility of eskolaite (Cr2O3) in 1.6-4.2 m aqueous HCl solutions was determined in situ at elevated pressures up to 1 GPa and temperatures ranging between 400 and 700 °C using synchrotron micro-X-ray fluorescence spectroscopy (μ-XRF). Determined concentrations of dissolved Cr ranged between about 900-18,000 ppm, with the highest concentrations found at 500 °C and 861 MPa. The Cr(III) solubility in aqueous HCl fluids is retrograde in the studied temperature range and increases with pressure. In addition, Cr(III) complexation in these fluids was explored by Raman spectroscopy on a 12.3 mass% HCl fluid in equilibrium with eskolaite at 400 and 600 °C, 0.3-1.6 GPa. All spectra show two prominent Cr-Cl stretching bands at about 275 and 325 cm-1, which display some fine structure, and in some spectra weak bands in the region between 380 and 500 cm-1. The sum of the integrated intensities of the two dominant bands reveals qualitatively the same changes with temperature along an isochore, with pressure at constant temperature, and with the time required for equilibration as the Cr(III) concentrations in the fluid determined by μ-XRF. Complementary ab initio molecular dynamics simulations of a 4 m HCl solution at two different densities (0.8 and 0.97 g/cm3) and temperatures (427 and 727 °C) were performed to investigate the vibrational properties of various(O)y3-x and (O)y(OH)z3-x-z complexes with 3⩽x+z⩽4 and 0⩽y⩽2. Quasi-normal mode analysis reveals that both the tetrahedral symmetric and antisymmetric Cr-Cl stretching vibrations of CrCl4(H2O)0-2- have characteristic frequencies in the range of the two strongest experimentally observed Raman bands, whereas Cr-O stretching vibrations of hydroxy-chloride complexes occur at wavenumbers above 400 cm-1. Solubility and complexation of Cr(III) depend strongly on the activities of Cl- and H+. At high H+ and Cl- activity, the results are consistent with CrCl(H2O)0-2-1-0 complexes as major Cr(III) species, the Cr coordination number of which increases with pressure by becoming more aquated. At low Cl- activity, i.e. in our study at high-temperature low-pressure conditions, the data indicate mixed CrClx((OH)z3-x-z complexes with Cl-Cr ratios less than three. In situ μ-XRF solubility experiments conducted with eskolaite + (H2O + 29 mass% Na2CO3) and kosmochlor + (H2O + 44 mass% Na2Si3O7) resulted in dissolved Cr concentrations at or below the detection limit of 500 ppm. Thus, acidic chloridic fluids seem to be more efficient agents for Cr(III) mobilization and transport at crustal conditions than aqueous alkali carbonate or silicate solutions.

C-104 high-level waste solids: Washing/leaching and solubility versus temperature studies

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

GJ Lumetta; DJ Bates; JP Bramson

This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing and caustic leaching on the composition of the C-104 HLW solids. The objective of this work was to determine the composition of the C-104 solids remaining after washing with 0.01 M NaOH or leaching with 3 M NaOH. Another objective of this test was to determine the solubility of the C-104 solids as a function of temperature. The work was conducted according to test plan BNFL-TP-29953-8, Rev. 0, ``Determination of the Solubility of HLW Sludge Solids.

Effects of treatment time and temperature on the DC corona pretreatment performance of waste activated sludge

NASA Astrophysics Data System (ADS)

Yu, GAO; Ning, ZHAO; Yongdi, DENG; Minghang, WANG; Boxue, DU

2018-02-01

In order to improve the anaerobic digestion efficiency of waste activated sludge (WAS), a pretreatment procedure should be carried out so as to disrupt the microbial cell structure, thus releasing intracellular organic matters. In this paper, a corona discharge triggered by a DC voltage was employed to pre-treat WAS for various time periods under different temperatures. The magnitude of the DC voltage was 4 kV at both negative and positive polarities. The changes in the soluble chemical oxygen demand, phosphorus and nitrogen content, and pH value within the WAS were utilized to estimate the pretreatment performance of the DC corona. It was found that with increasing treatment time, the pretreatment efficiency tends to be reduced. With increased temperature, the pretreatment efficiency appears to be better. It is suggested that the oxidative species and the active particles generated in the corona discharge play an important role in disrupting the microbial cell structure, which is dependent upon the treatment time and the temperature.

Protein conformational modifications and kinetics of water-protein interactions in milk protein concentrate powder upon aging: effect on solubility.

PubMed

Haque, Enamul; Bhandari, Bhesh R; Gidley, Michael J; Deeth, Hilton C; Møller, Sandie M; Whittaker, Andrew K

2010-07-14

Protein conformational modifications and water-protein interactions are two major factors believed to induce instability of protein and eventually affect the solubility of milk protein concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in protein conformation by Fourier transform infrared (FTIR) spectroscopy and principal component analysis (PCA), and water status (interaction of water with the protein molecule/surface) by measuring the transverse relaxation time (T(2)) with proton nuclear magnetic resonance ((1)H NMR). The solubility of MPC decreased significantly with aging, and this process was enhanced by increasing water activity (a(w)) and storage temperature. Minor changes in protein secondary structure were observed with FTIR, which indicated some degree of unfolding of protein molecules. PCA of the FTIR data was able to discriminate samples according to moisture content and storage period. Partial least-squares (PLS) analysis showed some correlation between FTIR spectral feature and solubility. The NMR T(2) results indicated the presence of three distinct populations of water molecules, and the proton signal intensity and T(2) values of proton fractions varied with storage conditions (humidity, temperature) and aging. Results suggest that protein/protein interactions may be initiated by unfolding of protein molecules that eventually affects solubility.

Klucel™ EF and ELF polymers for immediate-release oral dosage forms prepared by melt extrusion technology.

PubMed

Mohammed, Noorullah Naqvi; Majumdar, Soumyajit; Singh, Abhilasha; Deng, Weibin; Murthy, Narasimha S; Pinto, Elanor; Tewari, Divya; Durig, Thomas; Repka, Michael A

2012-12-01

The objective of this research work was to evaluate Klucel™ hydroxypropylcellulose (HPC) EF and ELF polymers, for solubility enhancement as well as to address some of the disadvantages associated with solid dispersions. Ketoprofen (KPR), a Biopharmaceutics Classification System class II drug with poor solubility, was utilized as a model compound. Preliminary thermal studies were performed to confirm formation of a solid solution/dispersion of KPR in HPC matrix and also to establish processing conditions for hot-melt extrusion. Extrudates pelletized and filled into capsules exhibited a carrier-dependent release with ELF polymer exhibiting a faster release. Tablets compressed from milled extrudates exhibited rapid release owing to the increased surface area of the milled extrudate. Addition of mannitol (MNT) further enhanced the release by forming micro-pores and increasing the porosity of the extrudates. An optimized tablet formulation constituting KPR, MNT, and ELF in a 1:1:1 ratio exhibited 90% release in 15 min similar to a commercial capsule formulation. HPC polymers are non-ionic hydrophilic polymers that undergo polymer-chain-length-dependent solubilization and can be used to enhance solubility or dissolution rate of poorly soluble drugs. Dissolution/release rate could be tailored for rapid-release applications by selecting a suitable HPC polymer and altering the final dosage form. The release obtained from pellets was carrier-dependent and not drug-dependent, and hence, such a system can be effectively utilized to address solubility or precipitation issues with poorly soluble drugs in the gastrointestinal environment.

SOME RARE-EARTH ALLOY SYSTEMS. I. La-Gd, La-Y, Gd-Y

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

Spedding, F.H.; Valletta, R.M.; Daane, A.H.

The La-Y, La--Gd, and Gd--Y alloy systems were examined by conventional metallurgical research techniques. As would be expected from the similarity of the parent metals, the Gd--Y system exhibits complete solid solubility across the system in both the alpha and beta regions, with nearly perfect behavior indicated by the essentially linear plots of lattice constants and other related data, The La--Y and La--Gd systems show complete solid solubility in the high temperature bcc region, with limited solubility in the room temperature forms. In the central region of these two systems at room temperature, an ordered phase with the samarium structuremore » is observed, Some correlation of structure and lattice constants of this phase with the properties of the related pure metals is observed. (auth)« less

Heat and corrosion resistant cast CN-12 type stainless steel with improved high temperature strength and ductility

DOEpatents

Mazias, Philip J [Oak Ridge, TN; McGreevy, Tim [Morton, IL; Pollard, Michael James [East Peoria, IL; Siebenaler, Chad W [Peoria, IL; Swindeman, Robert W [Oak Ridge, TN

2007-08-14

A cast stainless steel alloy and articles formed therefrom containing about 0.5 wt. % to about 10 wt. % manganese, 0.02 wt. % to 0.50 wt. % N, and less than 0.15 wt. % sulfur provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. Alloys of the present invention also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon. Such solution strengthening enhances the high temperature precipitation-strengthening benefits of fine dispersions of NbC. Such solid solution effects also enhance the stability of the austenite matrix from resistance to excess sigma phase or chrome carbide formation at higher service temperatures. The presence of sulfides is substantially eliminated.

The global distribution of ammonia emissions from seabird colonies

NASA Astrophysics Data System (ADS)

Riddick, S. N.; Dragosits, U.; Blackall, T. D.; Daunt, F.; Wanless, S.; Sutton, M. A.

2012-08-01

Seabird colonies represent a significant source of atmospheric ammonia (NH3) in remote maritime systems, producing a source of nitrogen that may encourage plant growth, alter terrestrial plant community composition and affect the surrounding marine ecosystem. To investigate seabird NH3 emissions on a global scale, we developed a contemporary seabird database including a total seabird population of 261 million breeding pairs. We used this in conjunction with a bioenergetics model to estimate the mass of nitrogen excreted by all seabirds at each breeding colony. The results combined with the findings of mid-latitude field studies of volatilization rates estimate the global distribution of NH3 emissions from seabird colonies on an annual basis. The largest uncertainty in our emission estimate concerns the potential temperature dependence of NH3 emission. To investigate this we calculated and compared temperature independent emission estimates with a maximum feasible temperature dependent emission, based on the thermodynamic dissociation and solubility equilibria. Using the temperature independent approach, we estimate global NH3 emissions from seabird colonies at 404 Gg NH3 per year. By comparison, since most seabirds are located in relatively cold circumpolar locations, the thermodynamically dependent estimate is 136 Gg NH3 per year. Actual global emissions are expected to be within these bounds, as other factors, such as non-linear interactions with water availability and surface infiltration, moderate the theoretical temperature response. Combining sources of error from temperature (±49%), seabird population estimates (±36%), variation in diet composition (±23%) and non-breeder attendance (±13%), gives a mid estimate with an overall uncertainty range of NH3 emission from seabird colonies of 270 [97-442] Gg NH3 per year. These emissions are environmentally relevant as they primarily occur as "hot-spots" in otherwise pristine environments with low anthropogenic emissions.

pH Shifting alters solubility characteristics and thermal stability of soy protein isolate and its globulin fractions in different pH, salt concentration, and temperature conditions.

PubMed

Jiang, Jiang; Xiong, Youling L; Chen, Jie

2010-07-14

Soy protein isolate (SPI), beta-conglycinin (7S), and glycinin (11S) were subjected to pH-shifting treatments, that is, unfolding at pH 1.5 or 12.0 followed by refolding at pH 7.0, to induce molten globule structures. Treated samples were analyzed for protein solubility, thermal stability, and aggregation in 0, 0.1, and 0.6 M NaCl solutions at pH 2.0-8.0. The pH(12) shifting resulted in drastic increases (up to 2.5-fold) in SPI solubility in the pH 6.0-7.0 range, especially at 0 M NaCl. The pH(1.5) shifting had a generally lesser effect on solubility. 11S exhibited a solubility pattern similar to that of SPI, but the solubility of 7S was unaffected by pH shifting except at 0.6 M NaCl. The pH shifting, notably at pH 12.0, produced soluble, disulfide-linked polymers from 11S and reduced (P < 0.05) its enthalpy but not its temperature of denaturation. Soy proteins structurally altered by pH shifting had a reduced sensitivity to thermal aggregation.

Structure and phase transitions of asphaltenes in solutions

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

Tar, M.M. de; Sheu, E.Y.; Storm, D.A.

The authors investigated the rheological properties of two vacuum resid fractions in a series of solvents. The authors measured the viscosity as a function of concentration and temperature respectively. In this study, two aspects were focused: (1) the concentration dependence of viscosity for the pentane soluble fractions in a series of n-alkane solvents for study of the particle structure, and (2) the temperature dependence of viscosity of the heptane insoluble fraction in toluene at various concentrations for the study of the phase transitions. From their results it was found that all the systems studied are Newtonian. The results for (1)more » show that the particles are approximately spherical and as the carbon number of the n-alkane solvent increases, the quality of the solvent increases, thereby increasing the particle solvation. This result is consistent with that reported in a recent paper by Ali and Saleem. Also, the particles were found to behave similarly to colloidal particles. As for (2), a glass-like transition was observed at 50% concentration (0.31 volume fraction) with glass transition temperature at about 254 K, while no structural or phase transitions were observed for concentrations below 50%.« less

Empirical Correlations for the Solubility of Pressurant Gases in Cryogenic Propellants

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory A.; Asipauskas, Marius; VanDresar, Neil T.

2010-01-01

We have analyzed data published by others reporting the solubility of helium in liquid hydrogen, oxygen, and methane, and of nitrogen in liquid oxygen, to develop empirical correlations for the mole fraction of these pressurant gases in the liquid phase as a function of temperature and pressure. The data, compiled and provided by NIST, are from a variety of sources and covers a large range of liquid temperatures and pressures. The correlations were developed to yield accurate estimates of the mole fraction of the pressurant gas in the cryogenic liquid at temperature and pressures of interest to the propulsion community, yet the correlations developed are applicable over a much wider range. The mole fraction solubility of helium in all these liquids is less than 0.3% at the temperatures and pressures used in propulsion systems. When nitrogen is used as a pressurant for liquid oxygen, substantial contamination can result, though the diffusion into the liquid is slow.

Influence of Working Temperature on The Formation of Electrospun Polymer Nanofibers

NASA Astrophysics Data System (ADS)

Yang, Guang-Zhi; Li, Hai-Peng; Yang, Jun-He; Wan, Jia; Yu, Deng-Guang

2017-01-01

Temperature is an important parameter during electrospinning, and virtually, all solution electrospinning processes are conducted at ambient temperature. Nanofiber diameters presumably decrease with the elevation of working fluid temperature. The present study investigated the influence of temperature variations on the formation of polymeric nanofibers during single-fluid electrospinning. The surface tension and viscosity of the fluid decreased with increasing working temperature, which led to the formation of high-quality nanofibers. However, the increase in temperature accelerated the evaporation of the solvent and thus terminated the drawing processes prematurely. A balance can be found between the positive and negative influences of temperature elevation. With polyacrylonitrile (PAN, with N, N-dimethylacetamide as the solvent) and polyvinylpyrrolidone (PVP, with ethanol as the solvent) as the polymeric models, relationships between the working temperature ( T, K) and nanofiber diameter ( D, nm) were established, with D = 12598.6 - 72.9 T + 0.11 T 2 ( R = 0.9988) for PAN fibers and D = 107003.4 - 682.4 T + 1.1 T 2 ( R = 0.9997) for PVP nanofibers. Given the fact that numerous polymers are sensitive to temperature and numerous functional ingredients exhibit temperature-dependent solubility, the present work serves as a valuable reference for creating novel functional nanoproducts by using the elevated temperature electrospinning process.

Mathematical models for prediction of rheological parameters in vinasses derived from sugar cane

NASA Astrophysics Data System (ADS)

Chacua, Leidy M.; Ayala, Germán; Rojas, Hernán; Agudelo, Ana C.

2016-04-01

The rheological behaviour of vinasses derived from sugar cane was studied as a function of time (0 and 600 s), soluble solids content (44 and 60 °Brix), temperature (10 and 50°C), and shear rate (0.33 and 1.0 s-1). The results indicated that vinasses were time-independent at 25°C, where shear stress values ranged between 0.01 and 0.08 Pa. Flow curves showed a shear-thinning rheological behaviour in vinasses with a flow behaviour index between 0.69 and 0.89, for temperature between 10 and 20°C. With increasing temperature, the flow behaviour index was modified, reaching values close to 1.0. The Arrhenius model described well the thermal activation of shear stress and the consistency coefficient as a function of temperature. Activation energy from the Arrhenius model ranged between 31 and 45 kJ mol-1. Finally, the consistency coefficient as a function of the soluble solids content and temperature was well fitted using an exponential model (R2 = 0.951), showing that the soluble solids content and temperature have an opposite effect on consistency coefficient values.

The Use Of Fluorescence Quenching To Measure Oxygen Concentration

NASA Astrophysics Data System (ADS)

Cox, M. E.; Dunn, B.

1986-01-01

The method of fluorescence quenching is used to measure the concentration of molecular oxygen. The method is rapid, reversible, and does not consume oxygen. The method may provide the basis for a unique biomedical sensor. The key to developing such a device lies in the choice of a fluorophor/polymer composite matrix having the desired optical and transport properties. Experimental results will be presented for certain parameters essential for assessing device development. The properties of interest include the kinetics of fluorescence quenching, the biomolecular rate constants, the temperature dependence of oxygen solubility and diffusivity in the composite matrix, and the oxygen diffusion coefficient. Poly(dimethyl siloxane) [PDMS] was chosen as the polymer host because it is biocompatible, hydrophobic, has a high diffusivity for the simple gases, and is easily bonded to fused silica. 9,10-diphenyl anthracene [9,10-D] was selected since it is readily soluble in a number of organic solvents, has an excitation spectrum in the near UV, an emission spectrum in the visible, a long fluorescence lifetime, and a high quantum yield. When incorporated into PDMS, the optical spectra of 9,10-D does not alter appreciably. The response time of the device is determined by the solution/diffusion kinetics of oxygen in PDMS. The solubility of oxygen in PDMS decreases with increasing temperature and an enthalpy of solution of off = -3.0 kcal/mole. (1) The diffusion of oxyzen in PDMS is found to obey an Arrhenius relation over the temperature range of 5'C to 450C with D = Do exp (-ED/RT) (2) where Do = 0.115 cm2/s (3) and ED = 4.77 kcal/mole. (4) Results of these studies indicate that an appropriate device, based on a fluorophor/polymer composite, for the measurement of oxygen concentration should be sensitive over those ranges which are important for physiological monitoring.

Thermally-responsive, nonflammable phosphonium ionic liquid electrolytes for lithium metal batteries: operating at 100 degrees celsius.

PubMed

Lin, X; Kavian, R; Lu, Y; Hu, Q; Shao-Horn, Y; Grinstaff, M W

2015-11-13

Rechargeable batteries such as Li ion/Li metal batteries are widely used in the electronics market but the chemical instability of the electrolyte limits their use in more demanding environmental conditions such as in automotive, oil exploration, or mining applications. In this study, a series of alkyl phosphonium ionic liquid electrolyte are described with high thermal stability and solubility for LiTFSI. A lithium metal battery (LMB) containing a tailored phosphonium ionic liquid/LiTFSI electrolyte operates at 100 °C with good specific capacities and cycling stability. Substantial capacity is maintained during 70 cycles or 30 days. Instant on-off battery operation is realized via the significant temperature dependence of the electrolyte material, demonstrating the robustness and potential for use at high temperature.

Kinetics of radiation-induced precipitation at the alloy surface

NASA Astrophysics Data System (ADS)

Lam, N. Q.; Nguyen, T.; Leaf, G. K.; Yip, S.

1988-05-01

Radiation-induced precipitation of a new phase at the surface of an alloy during irradiation at elevated temperatures was studied with the aid of a kinetic model of segregation. The preferential coupling of solute atoms with the defect fluxes gives rise to a strong solute enrichment at the surface, which, if surpassing the solute solubility limit, leads to the formation of a precipitate layer. The moving precipitate/matrix interface was accommodated by means of a mathematical scheme that transforms spatial coordinates into a reference frame in which the boundaries are immobile. Sample calculations were performed for precipitation of the γ'-Ni 3Si layer on Ni-Si alloys undergoing electron irradiation. The dependences of the precipitation kinetics on the defect-production rate, irradiation temperature, internal defect sink concentration and alloy composition were investigated systematically.

Physicochemical properties of valsartan and the effect of ethyl alcohol, propylene glycol and pH on its solubility.

PubMed

Mbah, C J

2005-11-01

The aqueous solubility and partition coefficient of valsartan were determined at room temperature. The effect of ethyl alcohol, propylene glycol and pH on its solubility was also investigated. It was found that both solvents increased the solubility of the drug in water. The solubilizing power of ethyl alcohol was found to be higher than that of propylene glycol. Valsartan solubility was also observed to increase at high pH values and its lipophilicity wasdemonstrated by the high positive value of the logarithm of partition coefficient.

Biodegradable "Smart" Polyphosphazenes with Intrinsic Multifunctionality as Intracellular Protein Delivery Vehicles.

PubMed

Martinez, Andre P; Qamar, Bareera; Fuerst, Thomas R; Muro, Silvia; Andrianov, Alexander K

2017-06-12

A series of biodegradable drug delivery polymers with intrinsic multifunctionality have been designed and synthesized utilizing a polyphosphazene macromolecular engineering approach. Novel water-soluble polymers, which contain carboxylic acid and pyrrolidone moieties attached to an inorganic phosphorus-nitrogen backbone, were characterized by a suite of physicochemical methods to confirm their structure, composition, and molecular sizes. All synthesized polyphosphazenes displayed composition-dependent hydrolytic degradability in aqueous solutions at neutral pH. Their formulations were stable at lower temperatures, potentially indicating adequate shelf life, but were characterized by accelerated degradation kinetics at elevated temperatures, including 37 °C. It was found that synthesized polyphosphazenes are capable of environmentally triggered self-assembly to produce nanoparticles with narrow polydispersity in the size range of 150-700 nm. Protein loading capacity of copolymers has been validated via their ability to noncovalently bind avidin without altering biological functionality. Acid-induced membrane-disruptive activity of polyphosphazenes has been established with an onset corresponding to the endosomal pH range and being dependent on polymer composition. The synthesized polyphosphazenes facilitated cell-surface interactions followed by time-dependent, vesicular-mediated, and saturable internalization of a model protein cargo into cancer cells, demonstrating the potential for intracellular delivery.

Solubility and dissolution thermodynamics of tetranitroglycoluril in organic solvents at 295-318 K

NASA Astrophysics Data System (ADS)

Zheng, Zhihua; Wang, Jianlong; Hu, Zhiyan; Du, Hongbin

2017-08-01

The solubility data of tetranitroglycoluril in acetone, methanol, ethanol, ethyl acetate, nitromethane and chloroform at temperatures ranging from 295-318 K were measured by gravimetric method. The solubility data of tetranitroglycoluril were fitted with Apelblat semiempirical equation. The dissolution enthalpy, entropy and Gibbs energy of tetranitroglycoluril were calculated using the Van't Hoff and Gibbs equations. The results showed that the Apelblat semiempirical equation was significantly correlated with solubility data. The dissolving process was endothermic, entropy-driven, and nonspontaneous.

A novel approach for analyzing glass-transition temperature vs. composition patterns: application to pharmaceutical compound+polymer systems.

PubMed

Kalogeras, Ioannis M

2011-04-18

In medicine, polymer-based materials are commonly used as excipients of poorly water-soluble drugs. The success of the encapsulation, as well as the physicochemical stability of the products, is often reflected on their glass transition temperature (T(g)) vs. composition (w) dependencies. The shape of the T(g)(w) patterns is critically influenced by polymer's molecular mass, drug molecule's shape and molecular volume, the type and degree of shielding of hydrogen-bonding capable functional groups, as well as aspects of the preparation process. By altering mixture's T(g) the amorphous solid form of the active ingredient may be retained at ambient or body temperatures, with concomitant improvements in handling, solubility, dissolution rate and oral bioavailability. Given the importance of the problem, the glass transitions observed in pharmaceutical mixtures have been extensively analyzed, aiming to appraise the state of mixing and intermolecular interactions. Here, accumulated experimental information on related systems is re-evaluated and comparably discussed under the light of a more effective and system-inclusive T(g)(w) equation. The present analysis indicates that free volume modifications and conformational changes of the macromolecular chains dominate, over enthalpic effects of mixing, in determining thermal characteristics and crystallization inhibition/retardation. Moreover, hydrogen-bonding and ion-dipole heterocontacts--although favorable of a higher degree of mixing--appear less significant compared to the steric hindrances and the antiplasticization proffered by the higher viscosity component. Copyright © 2011 Elsevier B.V. All rights reserved.

Tetragonal Chicken Egg White Lysozyme Solubility in Sodium Chloride Solutions

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth L.; Judge, Russell A.; Pusey, Marc L.

1998-01-01

The solubility of chicken egg white lysozyme, crystallized in the tetragonal form was measured in sodium chloride solutions from 1.6 to 30.7 C, using a miniature column solubility apparatus. Sodium chloride solution concentrations ranged from 1 to 7% (w/v). The solutions were buffered with 0.1 M sodium acetate buffer with the solubility being measured at pH values in 0.2 pH unit increments in the range pH 4.0 to 5.4, with data also included at pH 4.5. Lysozyme solubility was found to increase with increases in temperature and decreasing salt concentration. Solution pH has a varied and unpredictable effect on solubility.

Sulfur solubility in hydrous Etna Basalt at temperatures from 1150 to 1250 °C and 200 MPa

NASA Astrophysics Data System (ADS)

Beermann, O.; Nowak, N.; Botcharnikov, R. E.; Holtz, F.

2009-04-01

Degassing of magmatic volatiles is strongly dependent on fluid-melt interaction at the oneset of degassing under given pressure and temperature. Most magmatic fluids are composed of hydrous multicomponental mixtures, e.g. H-O-C-S-Cl-F-Br bearing fluids. In particular the partitioning behaviour of S and Cl between basaltic melt and hydrous fluid is of interest, because the S/Cl ratio of emitted volcanic gasses correlate to the eruption style (e.g. [1], [2], [3]). In particular, this was also observed for the 2002 eruption of Mt. Etna (Sicily) [4], which is one of the worlds most active and best investigated volcanoes. Since now, there even exist no reliable data on the solubility of sulfur in hydrous silicic melts at geologic relevant temperatures for basaltic magmas (above 1050 °C), because sulfur is known to be a very aggressive component limiting the application of experimental approaches that use noble metal capsules, especially Pt and AuPd. Thus, the experiments in this study, concerning the solubility of S in natural hydrous Etna basalt at 200 MPa and temperatures from 1150 to 1250 °C at fO2 ~ NNO + 2.5 and 1200 °C at fO2 ~ NNO, were performed in olivine-AuPd double capsules, using single crystal olivine capsules (San Carlos olivine) as sample containers, which were inserted into outer Au80Pd20 capsules. The starting material was a fused and water presaturated trachybasalt from Mt. Etna (2001 eruption), containing 5 wt.% H2O. For sulfur source pyrrhotine (FeS) was used, obtaining initial S concentrations between 1-1.5 wt.% (with respect to the amount of starting material). For some experiments an olivine disc was placed between FeS and starting glass powder to avoid FeS dispersion in the melt. All experiments were conducted in internally heated argon pressure vessels (IHPV) equipped with rapid quench device. For the reduced runs an Ar-H2 mixture was load into the vessel and the H2 pressure was monitored, using the shaw membrane technique. The experimental run time was 6-24 h at 1200, 24 h at 1250°C and 67 h at 1150 °C. All glasses obtained from these experiments contained FeS and were enriched in MgO due to reequilibration with MgO-rich olivine. Independent on the run duration, each of the experimental glasses had large variations of S concentration, ranging from 500 to 1600 ppm S at ~ NNO and 250 to 3000 ppm S at ~ NNO + 2.5 (calculated by the S peak shift of WDS spectra, recorded by electron microprobe analysis), where the highest S concentrations were measured near to the FeS source material. However, no direct dependence of temperature on the S solubility and, furthermore, no correlation on S concentration, dependent on the distance to the FeS source was observed, indicating that mobilisation of S seems to be dominated by other mechanisms (e.g. convection) than diffusion. Water concentrations of H2O-presaturated basaltic glasses decreased from 5 wt.% to ~ 2 wt.% (IR-analysis). No sulfur could be detected outside the olivine containers, improoving this experimental setup to be a sufficient barrier for sulfur or S-rich compounds. To get more reliable data, a longer run duration (> 3 d) and a more detailed determination of S species, prevailing in the glasses, is required. [1] Thordarson et al. (1996) Bull. Volcanol. 58, 205-225. [2] Harms & Schmincke (2000) Contrib. Mineral. Petrol. 138, 84-98. [3] Webster et al. (2001) Mineral. Petrol. 73, 177-200. [4] Aiuppa et al. (2004) EPSL 222, 469-483.

Effect of rhamnolipid biosurfactant on solubilization of polycyclic aromatic hydrocarbons.

PubMed

Li, Shudong; Pi, Yongrui; Bao, Mutai; Zhang, Cong; Zhao, Dongwei; Li, Yiming; Sun, Peiyan; Lu, Jinren

2015-12-15

Rhamnolipid biosurfactant-producing bacteria, Bacillus Lz-2, was isolated from oil polluted water collected from Dongying Shengli oilfield, China. The factors that influence PAH solubilization such as biosurfactant concentration, pH, ionic strength and temperature were discussed. The results showed that the solubilities of naphthalene, phenanthrene and pyrene increased linearly with the rise of rhamnolipid biosurfactant dose above the biosurfactant critical micelle concentration (CMC). Furthermore, the molar solubilization ratio (MSR) values decreased in the following order: naphthalene>phenanthrene>pyrene. However, the solubility percentage increased and followed the opposite order: pyrene>phenanthrene>naphthalene. The solubilities of PAHs in rhamnolipid biosurfactant solution increased with the rise of pH and ionic strength, and reached the maximum values under the conditions of pH11 and NaCl concentration 8 g · L(-1). The solubility of phenanthrene and pyrene increased with the rise of temperature. Copyright © 2015 Elsevier Ltd. All rights reserved.

Metal chelate affinity precipitation of RNA and purification of plasmid DNA

NASA Technical Reports Server (NTRS)

Balan, Sindhu; Murphy, Jason; Galaev, Igor; Kumar, Ashok; Fox, George E.; Mattiasson, Bo; Willson, Richard C.

2003-01-01

The affinity of metal chelates for amino acids, such as histidine, is widely used in purifying proteins, most notably through six-histidine 'tails'. We have found that metal affinity interactions can also be applied to separation of single-stranded nucleic acids through interactions involving exposed purines. Here we describe a metal affinity precipitation method to resolve RNA from linear and plasmid DNA. A copper-charged copolymer of N-isopropyl acrylamide (NIPAM) and vinyl imidazole (VI) is used to purify plasmid from an alkaline lysate of E. coli. The NIPAM units confer reversible solubility on the copolymer while the imidazole chelates metal ions in a manner accessible to interaction with soluble ligands. RNA was separated from the plasmid by precipitation along with the polymer in the presence of 800 mM NaCl. Bound RNA could be recovered by elution with imidazole and separated from copolymer by a second precipitation step. RNA binding showed a strong dependence on temperature and on the type of buffer used.

A study of the bio-accessibility of welding fumes.

PubMed

Berlinger, Balázs; Ellingsen, Dag G; Náray, Miklós; Záray, Gyula; Thomassen, Yngvar

2008-12-01

The respiratory bio-accessibility of a substance is the fraction that is soluble in the respiratory environment and is available for absorption. In the case of respiratory exposure the amount of absorbed substance plays a main role in the biological effects. Extensive bio-accessibility studies have always been an essential requirement for a better understanding of the biological effects of different workplace aerosols, such as welding fumes. Fumes generated using three different welding techniques, manual metal arc (MMA) welding, metal inert gas (MIG) welding, and tungsten inert gas (TIG) welding were investigated in the present study. Each technique was used for stainless steel welding. Welding fumes were collected on PVC membrane filters in batches of 114 using a multiport air sampler. Three different fluids were applied for the solubility study: deionised water and two kinds of lung fluid simulants: lung epithelial lining fluid simulant (Gamble's solution) and artificial lung lining fluid simulant (Hatch's solution). In order to obtain sufficient data to study the tendencies in solubility change with time, seven different leaching periods were used (0.5, 1, 2, 4, 8, 16, 24 h), each of them with three replicates. The effect of dissolution temperature was also studied. The total amounts of selected metals in the three different welding fumes were determined after microwave-assisted digestion with the mixture of aqua regia and hydrofluoric acid. The most obvious observation yielded by the results is that the solubility of individual metals varies greatly depending on the welding technique, the composition of the leaching fluid and leaching time. This study shows that the most reasonable choice as a media for the bio-assessment of solubility might be Hatch's solution by a dissolution time of 24 h.

Qrtzgeotherm: An ActiveX component for the quartz solubility geothermometer

NASA Astrophysics Data System (ADS)

Verma, Mahendra P.

2008-12-01

An ActiveX component, QrtzGeotherm, to calculate temperature and vapor fraction in a geothermal reservoir using quartz solubility geothermometry was written in Visual Basic 6.0. Four quartz solubility equations along the liquid-vapor saturation curve: (i) a quadratic equation of 1/ T and pressure, (ii) a linear equation relating log SiO 2 to the inverse of absolute temperature ( T), (iii) a polynomial of T including logarithmic terms and (iv) temperature as a polynomial of SiO 2 including logarithmic terms are programmed. The QrtzGeotherm has input parameters: (i) HRes—the reservoir enthalpy (kJ/kg), (ii) SiO2TD—silica concentration in total discharge (ppm), (iii) GeoEq—number of quartz solubility equation and (iv) TempGuess—a guess value of the reservoir temperature (°C). The reservoir enthalpy Hres is assumed to be the same as the total discharge enthalpy HR. The output parameters are (i) TempRes—reservoir temperature (°C) and (ii) VapRes—reservoir vapor fraction. The first step is to calculate the total discharge concentration of silica SiO2TD from the concentration of silica SiO2Col of separated water, sampled after N-separations of vapor and water. To use QrtzGeotherm in MS-Excel, three functions SiO2TD, GeoResTemp and GeoResVap for an N-stage separation of geothermal reservoir fluid are written in Visual Basic for Application (VBA). Similarly, a demonstration program, QrtzGeothrm, is written in Visual Basic 6.0.

The Toxicological Geochemistry of Dusts, Soils, and Other Earth Materials: Insights From In Vitro Physiologically-based Geochemical Leach Tests

NASA Astrophysics Data System (ADS)

Plumlee, G. S.; Ziegler, T. L.; Lamothe, P.; Meeker, G. P.; Sutley, S.

2003-12-01

Exposure to mineral dusts, soils, and other earth materials results in chemical reactions between the materials and different body fluids that include, depending upon the exposure route, lung fluids, gastrointestinal fluids, and perspiration. In vitro physiologically-based geochemical leach tests provide useful insights into these chemical reactions and their potential toxicological implications. We have conducted such leach tests on a variety of earth materials, including asbestos, volcanic ash, dusts from dry lake beds, mine wastes, wastes left from the roasting of mercury ores, mineral processing wastes, coal dusts and coal fly ash, various soils, and complex dusts generated by the World Trade Center collapse. Size-fractionated samples of earth materials that have been well-characterized mineralogically and chemically are reacted at body temperature (37 C) for periods from 2 hours up to multiple days with various proportions of simulated lung, gastric, intestinal, and/or plasma-based fluids. Results indicate that different earth materials may have quite different solubility and dissolution behavior in vivo, depending upon a) the mineralogic makeup of the material, and b) the exposure route. For example, biodurable minerals such as asbestos and volcanic ash particles, whose health effects result because they dissolve very slowly in vivo, bleed off low levels of trace metals into the simulated lung fluids; these include metals such as Fe and Cr that are suspected by health scientists of contributing to the generation of reactive oxygen species and resulting DNA damage in vivo. In contrast, dry lake bed dusts and concrete-rich dusts are highly alkaline and bioreactive, and cause substantial pH increases and other chemical changes in the simulated body fluids. Many of the earth materials tested contain a variety of metals that can be quite soluble (bioaccessible), depending upon the material and the simulated body fluid composition. For example, due to their acidic pH and high chloride concentrations, simulated gastric fluids are most efficient at solubilizing metals such as Hg, Pb, Zn, and others that form strong chloride complexes; although these metals tend to partially reprecipitate in the near-neutral simulated intestinal fluids, complexes with organic ligands (i.e., amino and carboxylic acids) enhance their solubility. These metals are also quite soluble in near-neutral, protein-rich plasma-based fluids because they form strong complexes with the proteins. In contrast, metalloids that form oxyanion species (such as As, Cr, Mo, W) are commonly more soluble in near-neutral pH simulated lung fluids than in simulated gastric fluids.

Carbonate mineral solubility at low temperatures in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system

NASA Astrophysics Data System (ADS)

Marion, Giles M.

2001-06-01

Carbonate minerals have played an important role in the geochemical evolution of Earth, and may have also played an important role in the geochemical evolution of Mars and Europa. Several models have been published in recent years that describe chloride and sulfate mineral solubilities in concentrated brines using the Pitzer equations. Few of these models are parameterized for subzero temperatures, and those that are do not include carbonate chemistry. The objectives of this work are to estimate Pitzer-equation bicarbonate-carbonate parameters and carbonate mineral solubility products and to incorporate them into the FREZCHEM model to predict carbonate mineral solubilities in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system at low temperatures (≤25°C) with a special focus on subzero temperatures. Most of the Pitzer-equation parameters and equilibrium constants are taken from the literature and extrapolated into the subzero temperature range. Solubility products for 14 sodium, potassium, magnesium, and calcium bicarbonate and carbonate minerals are included in the model. Most of the experimental data are at temperatures ≥ -8°C; only for the NaHCO 3-NaCl-H 2O and Na 2CO 3-NaCl-H 2O systems are there bicarbonate and carbonate data to temperatures as low as -21.6°C. In general, the fit of the model to the experimental data is good. For example, calculated eutectic temperatures and compositions for NaHCO 3, Na 2CO 3, and their mixtures with NaCl and Na 2SO 4 salts are in good agreement with experimental data to temperatures as low as -21.6°C. Application of the model to eight saline, alkaline carbonate waters give predicted pHs ranging from 9.2 to 10.2, in comparison with measured pHs that range from 8.7 to 10.2. The model suggests that the CaCO 3 mineral that precipitates during seawater freezing is probably calcite and not ikaite. The model demonstrates that a proposed salt assemblage for the icy surface of Europa consisting of highly hydrated MgSO 4 salts and natron (Na 2CO 3 · 10H 2O) is an incompatible salt assemblage.

Solubility constants of hydroxyl sodalite at elevated temperatures evaluated from hydrothermal experiments: Applications to nuclear waste isolation

DOE PAGES

Xiong, Yongliang

2016-09-17

In this study, solubility constants of hydroxyl sodalite (ideal formula, Na 8[Al 6Si 6O 24][OH] 2·3H 2O) from 25°C to 100°C are obtained by applying a high temperature Al—Si Pitzer model to evaluate solubility data on hydroxyl sodalite in high ionic strength solutions at elevated temperatures. A validation test comparing model-independent experimental data to model predictions demonstrates that the solubility values produced by the model are in excellent agreement with the experimental data. In addition, the equilibrium constants obtained in this study have a wide range of applications, including synthesis of hydroxyl sodalite, de-silication in the Bayer process for extractionmore » of alumina, and the performance of proposed sodalite waste forms in geological repositories in various lithologies including salt formations. The thermodynamic calculations based on the equilibrium constants obtained in this work indicate that the solubility products in terms of m ΣAl×m ΣSi for hydroxyl sodalite are very low (e.g., ~10 -13 [mol·kg -1] 2 at 100°C) in brines characteristic of salt formations, implying that sodalite waste forms would perform very well in repositories located in salt formations. Finally, the information regarding the solubility behavior of hydroxyl sodalite obtained in this study provides guidance to investigate the performance of other pure end-members of sodalite such as chloride- and iodide-sodalite, which may be of interest for geological repositories in various media.« less

Predicting CO2 Solubility in Imidazole Ionic Liquids for Use in Absorption Refrigeration Systems by Using the Group Contribution Equation of State Method

NASA Astrophysics Data System (ADS)

Wu, Wei-Dong; Wu, Jun; Hou, Yong; Su, Lin; Zhang, Hua

2017-09-01

Traditional absorption refrigeration such as H2O-LiBr- and NH3-H2O-based refrigeration has limited applications because of several issues, including crystallization, corrosion, and large volume. CO2-ionic liquids (ILs) as new absorption working pairs were investigated in this study. The objective was to use the group contribution equation of state (GC-EOS) method to predict the solubilities of binary systems containing high-pressure CO2-imidazole bis(trifluoromethanesulfonimide) ILs and to investigate the applicability and accuracy of the GC-EOS model. The results showed that at pressures up to 11.0 MPa and temperatures of 273 K to 400 K, the CO2 solubility in the ILs increased with increasing system pressure but decreased with increasing temperature, and its variation rate was lower at higher pressures or temperatures. Also, CO2 solubility increased in the order of [emim][Tf2N] < [bmim][Tf2N] < [hmim][Tf2N] < [omim][Tf2N], indicating that longer alkyl chains of identical IL families resulted in higher CO_{2 } solubility. The model prediction of CO2 solubility in the four different ILs showed reasonable consistency with the corresponding experimental results from the literature; the largest deviation was 5.7 % for CO2-[emim][Tf2N]. Therefore, it can be concluded that the GC-EOS model is a promising theoretical solution that can be used to search for suitable CO2-IL working pairs for absorption refrigeration systems.

Aphid Gel Saliva: Sheath Structure, Protein Composition and Secretory Dependence on Stylet-Tip Milieu

PubMed Central

Will, Torsten; Steckbauer, Kathrin; Hardt, Martin; van Bel, Aart J. E.

2012-01-01

In order to separate and analyze saliva types secreted during stylet propagation and feeding, aphids were fed on artificial diets. Gel saliva was deposited as chains of droplets onto Parafilm membranes covering the diets into which watery saliva was secreted. Saliva compounds collected from the diet fluid were separated by SDS-PAGE, while non-soluble gel saliva deposits were processed in a novel manner prior to protein separation by SDS-PAGE. Soluble (watery saliva) and non-soluble (gel saliva) protein fractions were significantly different. To test the effect of the stylet milieu on saliva secretion, aphids were fed on various diets. Hardening of gel saliva is strongly oxygen-dependent, probably owing to formation of sulfide bridges by oxidation of sulphydryl groups. Surface texture of gel saliva deposits is less pronounced under low-oxygen conditions and disappears in dithiothreitol containing diet. Using diets mimicking sieve-element sap and cell-wall fluid respectively showed that the soluble protein fraction was almost exclusively secreted in sieve elements while non-soluble fraction was preferentially secreted at cell wall conditions. This indicates that aphids are able to adapt salivary secretion in dependence of the stylet milieu. PMID:23056521

Determination of the solubility of tin indium oxide using in situ and ex x-ray diffraction

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

Gonzalez, G. B.; Mason, T. O.; Okasinski, J. S.

A novel approach to determine the thermodynamic solubility of tin in indium oxide via the exsolution from tin overdoped nano-ITO powders is presented. High-energy, in situ and ex situ synchrotron X-ray diffraction was utilized to study the solubility limit at temperatures ranging from 900 C to 1375 C. The tin exsolution from overdoped nanopowders and the formation of In{sub 4}Sn{sub 3}O{sub 12} were observed in situ during the first 4-48 h of high-temperature treatment. Samples annealed between 900 C and 1175 C were also studied ex situ with heat treatments for up to 2060 h. Structural results obtained from Rietveldmore » analysis include compositional phase analysis, atomic positions, and lattice parameters. The tin solubility in In{sub 2}O{sub 3} was determined using the phase analysis compositions from X-ray diffraction and the elemental compositions obtained from X-ray fluorescence. Experimental complications that can lead to incorrect tin solubility values in the literature are discussed.« less

Soluble Graphene Nanosheets from Recycled Graphite of Spent Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Zhao, Liangliang; Liu, Xiya; Wan, Chuanyun; Ye, Xiangrong; Wu, Fanhong

2018-02-01

Soluble graphene nanosheets are fabricated from recycled graphite of spent lithium ion batteries through a modified Hammers process followed by deoxygenation with NaOH-KOH eutectic. Ultrasonic exfoliation in N-methyl-pyrrolidone indicates the loosened graphene layers in recycled graphite are prone to exfoliation. Reduction of the exfoliated graphene oxide sheets was conducted in molten NaOH-KOH eutectic at different temperatures. The results show that molten NaOH-KOH effectively eliminates the unsaturated oxygen-containing moieties from the exfoliated graphene oxide sheets while creating more hydroxyl functional groups. Higher temperature treatment is more prone to remove hydroxyls while producing the shrinkage on the surface of graphene sheets. Graphene sheet with a good solubility is produced when the graphene oxide is heat-treated at 220 °C for 10 h. After reduction, the graphene oxide sheets exhibit excellent dispersibility or solubility in water, ethanol and other polar solvents, therefore being highly desirable for solution processing of graphene materials. Such study not only identifies a high-quality stockpile to prepare soluble graphene but also paves a feasible alternative of graphite recycling from spent lithium batteries.

Enzyme-linked immunosorbent assay for a soluble antigen of Renibacterium salmoninarum, the causative agent for salmonid bacterial kidney disease

USGS Publications Warehouse

Pascho, R.J.; Mulcahy, D.

1987-01-01

A double-antibody enzyme-linked immunosorbent assay (ELISA) for detection of a soluble fraction of Renibacterium salmoninarum was developed from components extracted from the supernatant of an R. salmoninarum broth culture. The Costar® Serocluster™ EIA microplate gave the highest absorbance and signal-to-noise ratios among seven types tested. Including Tween 80 in the wash buffer resulted in higher absorbances than Tween 20 when antigen was present. Background absorbance did not increase when Tween 80 was added to the wash buffer, but did when Tween 80 replaced Tween 20 in antigen and conjugate diluents. Adsorption of coating antibody peaked within 4 h at 37 °C and 16 h at 4 °C. Antigen attachment to antibody-coated microplate wells depended more on incubation temperature than duration; we adopted a 3-h incubation at 25 °C. Conjugate incubation for longer than 1 h at 37 °C or 3 h at 25 °C resulted in unacceptable background levels. No cross-reactions resulted from heat-extracted antigens of 10 other species of bacteria. The optimized ELISA is a 6-h test that enables detection of levels of soluble antigen as low as 2–20 ng.

Effects of Cultivating Conditions on the Water Soluble Polysaccharides Content of Ganoderma lucidum Mycelium in Submerged Flask Culture

NASA Astrophysics Data System (ADS)

Rosyida, V. T.; Hayati, S. N.; Apriyana, W.; Darsih, C.; Hernawan; Poeloengasih, C. D.

2017-12-01

The carcinostatic substance in Ganoderma lucidum (Fr.) Karst (Polyporaceae) is a water soluble polysaccharides (WSP) which might be useful in immunotherapy. Attempt to produce effective substances from cultured mycelia is important to carry out since solid cultivation is a time consuming and quality fluctuating. The effects of cultivating conditions on the water soluble polysaccharides content of G. Lucidum mycelium were investigated in submerged flask cultures. Culture from fruiting bodies was maintained on potato dextrose-agar slope. Slopes were inoculated and incubated at 30°C for 7 days, and stored at 4°C. The flask experiments were performed in 100 ml erlenmeyer flasks containing 20 ml of the sterilized media. Actively growing mycelia (1 piece, 5 mm X 5 mm) from a newly prepared slant culture (about 7 days incubation at 30°C) were inoculated into the flask. The pH was measured and adjusted to the desired value by addition of either 4 M HCl or 2.5 M NaOH. Incubation temperature were 20, 25, and 30°C. At the end of inoculation period (14 days) mycelium consisting of individual pellets was harvested and wash for the analysis. WSP content was analysed using phenol-sulfuric acid method. The optimal initial pH for metabolite production would depend on the culture medium. Generally, high values of pH, such as 9, negatively affect both cell growth and WSP production. The optimum temperature range for the high G. lucidum mycelium and WSP production were found to be 25 - 30 °C at pH values 5 - 7 in both of media.

The solubility of the tetragonal form of hen egg white lysozyme from pH 4.0 to 5.4

NASA Technical Reports Server (NTRS)

Cacioppo, Elizabeth; Pusey, Marc L.

1991-01-01

Hen egg white lysozyme solubilities in the presence of the tetragonal crystal form have been determined. Conditions investigated cover the pH range 4.0 to 5.4, varying from 2.0 to 7.0 percent NaCl concentrations and from 4 to 25 C. In all instances, the solubilities were found to increase with temperature and decrease with increasing salt concentration. The effects of pH were more complex, showing a decreasing solubility with increasing pH at low salt concentration and an increasing solubility with increasing pH at high salt concentration.

Absorption of Carbon Dioxide in the aqueous solution of Diethanolamine (DEA) blended with 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate [BmPyrr][OTf] at high pressure

NASA Astrophysics Data System (ADS)

Jamaludin, S. N.; Salleh, R. M.

2018-03-01

Solubility data of carbon dioxide (CO2) in aqueous Diethanolamine (DEA) blended with 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate [Bmpyrr][OTf] were measured at temperature 313.15K, 323.15K, 333.15K and pressure from 500psi up to 700 psi. The experiments covered over the concentration range of 0-10wt% for [Bmpyrr][OTf] and 30-40wt% for DEA. The solubility of CO2 was evaluated by measuring the pressure drop in high pressure stirred absorption cell reactor. The experimental results showed that CO2 loading in all DEA-[BmPyrr][OTf] mixtures studied increases with increasing of CO2 partial pressure and temperature. It was also found that the CO2 loading capacity increase significantly as the concentration of [Bmpyrr][OTf] increases. Jou and Mather model was used to predict the solubility of CO2 in the mixtures where the experimental data were correlated as a function of temperature and CO2 partial pressure. It was found that the model was successful in predicting the solubility behavior of the aqueous DEA-[Bmpyrr][OTf] systems considered in this study.

Formation of multiferroic PbTiO3/PbFe12O19 composite by exceeding the solubility limit of Fe in PbTiO3

NASA Astrophysics Data System (ADS)

Jaffari, G. Hassnain; Bilal, M.; Ur Rahman, Jamil; Lee, Soonil

2017-09-01

PbTiO3/PbFe12O19 composites have been synthesized by keeping the Fe concentration (x) in PbFexTi1-xO3 beyond solubility limit, i.e., x > 0.1% and 5% Pb excess. Both these factors have been successfully utilized to extract Fe doped PbTiO3 tetragonal phase which is composited with Magnetoplumbite (PbFe12O19) phase. A systematic evolution of the tetragonality of the former and improved stoichiometry of the later constituent has been observed. As x increases, emergence of additional Raman mode around 650 cm-1 with Fe addition was observed. Systematic increase in the relative intensity of this mode with x, showed that this mode corresponds to the magnetoplumbite phase. In addition to that resultant composite exhibited noticeable systematic decrease in the value of the energy gap as a function of x. Increasing Fe concentration in PbTiO3 constituent, led to monotonic decrease in c/a and increase in strain experienced by PbTiO3. Increase in the value of the saturation polarization was observed up to x = 0.4, which is identified to be associated with the strain induced by the dopant. A comprehensive magnetic characterization revealed monotonic decrease in magnetization with temperature for all compositions. Finally, we found an anomalous temperature dependent trend in the magnetic coercivity which is explained in terms of low temperature decrease in effective magnetic anisotropy by including magneto-electric coupling. Both constituent phases in the composite being ferroelectric and ferromagnetic at room temperature led to formation of better multiferroic properties and exhibited tunable physical properties with x.

Poly(ether ester) Ionomers as Water-Soluble Polymers for Material Extrusion Additive Manufacturing Processes.

PubMed

Pekkanen, Allison M; Zawaski, Callie; Stevenson, André T; Dickerman, Ross; Whittington, Abby R; Williams, Christopher B; Long, Timothy E

2017-04-12

Water-soluble polymers as sacrificial supports for additive manufacturing (AM) facilitate complex features in printed objects. Few water-soluble polymers beyond poly(vinyl alcohol) enable material extrusion AM. In this work, charged poly(ether ester)s with tailored rheological and mechanical properties serve as novel materials for extrusion-based AM at low temperatures. Melt transesterification of poly(ethylene glycol) (PEG, 8k) and dimethyl 5-sulfoisophthalate afforded poly(ether ester)s of sufficient molecular weight to impart mechanical integrity. Quantitative ion exchange provided a library of poly(ether ester)s with varying counterions, including both monovalent and divalent cations. Dynamic mechanical and tensile analysis revealed an insignificant difference in mechanical properties for these polymers below the melting temperature, suggesting an insignificant change in final part properties. Rheological analysis, however, revealed the advantageous effect of divalent countercations (Ca 2+ , Mg 2+ , and Zn 2+ ) in the melt state and exhibited an increase in viscosity of two orders of magnitude. Furthermore, time-temperature superposition identified an elevation in modulus, melt viscosity, and flow activation energy, suggesting intramolecular interactions between polymer chains and a higher apparent molecular weight. In particular, extrusion of poly(PEG 8k -co-CaSIP) revealed vast opportunities for extrusion AM of well-defined parts. The unique melt rheological properties highlighted these poly(ether ester) ionomers as ideal candidates for low-temperature material extrusion additive manufacturing of water-soluble parts.

Redox-dependent solubility of technetium in low activity waste glass

NASA Astrophysics Data System (ADS)

Soderquist, Chuck Z.; Schweiger, Michael J.; Kim, Dong-Sang; Lukens, Wayne W.; McCloy, John S.

2014-06-01

The solubility of technetium was measured in a Hanford low activity waste (LAW) glass simulant, to investigate the extent that technetium solubility controls the incorporation of technetium into LAW glass. A series of LAW glass samples, spiked with 500-6000 ppm of Tc as potassium pertechnetate, were melted at 1000 °C in sealed fused quartz ampoules. Technetium solubility was determined in the quenched bulk glass to be 2000-2800 ppm, with slightly reducing conditions due to choice of milling media resulting in reductant contamination and higher solubility. The chemical form of technetium obtained by X-ray absorption near edge spectroscopy is mainly isolated, octahedrally-coordinated Tc(IV), with a minority of Tc(VII) in some glasses and TcO2 in two glasses. The concentration and speciation of technetium depends on glass redox and amount of technetium added. Salts formed at the top of higher technetium loaded glasses during the melt. The results of this study show that technetium solubility should not be a factor in technetium retention during melting of Hanford LAW glass.

Calculating the Solubilities of Drugs and Drug-Like Compounds in Octanol.

PubMed

Alantary, Doaa; Yalkowsky, Samuel

2016-09-01

A modification of the Van't Hoff equation is used to predict the solubility of organic compounds in dry octanol. The new equation describes a linear relationship between the logarithm of the solubility of a solute in octanol to its melting temperature. More than 620 experimentally measured octanol solubilities, collected from the literature, are used to validate the equation without using any regression or fitting. The average absolute error of the prediction is 0.66 log units. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Solubility and thermodynamics of apremilast in different mono solvents: Determination, correlation and molecular interactions.

PubMed

Shakeel, Faiyaz; Haq, Nazrul; Alanazi, Fars K; Alsarra, Ibrahim A

2017-05-15

The solubility data of recently launched poorly soluble antipsoriatic drug apremilast (APM) in any mono solvent or cosolvent mixtures with respect to temperature are not available in literature. Hence, in this research work, the solubility of APM in twelve different mono solvents namely "water, methanol, ethanol, isopropanol (IPA), ethylene glycol (EG), propylene glycol (PG), 1-butanol, 2-butanol, ethyl acetate (EA), dimethyl sulfoxide (DMSO), polyethylene glycol-400 (PEG-400) and Transcutol ® " was determined at temperatures "T=298.2K to 318.2K" and pressure "p=0.1 MPa". Eexperimental solubilities of APM in mole fraction were determined by a static equilibrium method using high performance liquid chromatography at 254nm. Experimental solubilities of APM in mole fraction were correlated well with "Van't Hoff and Apelblat models". The solubilities of APM in mole fraction were recorded highest in DMSO (9.91×10 -2 ), followed by EA (2.54×10 -2 ), Transcutol (2.51×10 -2 ), PEG-400 (2.16×10 -2 ),PG (4.01×10 -3 ), EG (1.61×10 -3 ), IPA (4.96×10 -4 ), 1-butanol (4.18×10 -4 ), 2-butanol (3.91×10 -4 ), methanol (2.25×10 -4 ), ethanol (2.20×10 -4 ) and water (1.29×10 -6 ) at "T=318.2K" and similar results were also obtained at each temperature evaluated. The molecular interactions between solute and solvent molecules were evaluated by the determination of activity coefficients. Based on activity coefficients, the higher solute-solvents molecular interactions were recorded in APM-DMSO, APM-EA, APM-Transcutol and APM-PEG-400 in comparison with other combination of solute and solvents. "Apparent standard thermodynamic parameters" of APM indicated an "endothermic and entropy-driven dissolution" of APM in all mono solvents evaluated. Based on these results, APM was proposed as freely soluble in DMSO, EA and Transcutol, sparingly soluble in PEG0-400, slightly soluble in methanol, ethanol, IPA, EG, PG, 1-butanol and 2-butanol and practically insoluble in water. Hence, DMSO, EA and Transcutol were selected as the best solvents and water and ethanol were selected as the anti-solvents for APM. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of infant formula quality and composition using Vis-NIR, MIR and Raman process analytical technologies.

PubMed

Wang, Xiao; Esquerre, Carlos; Downey, Gerard; Henihan, Lisa; O'Callaghan, Donal; O'Donnell, Colm

2018-06-01

In this study, visible and near-infrared (Vis-NIR), mid-infrared (MIR) and Raman process analytical technologies were investigated for assessment of infant formula quality and compositional parameters namely preheat temperature, storage temperature, storage time, fluorescence of advanced Maillard products and soluble tryptophan (FAST) index, soluble protein, fat and surface free fat (SFF) content. PLS-DA models developed using spectral data with appropriate data pre-treatment and significant variables selected using Martens' uncertainty test had good accuracy for the discrimination of preheat temperature (92.3-100%) and storage temperature (91.7-100%). The best PLS regression models developed yielded values for the ratio of prediction error to deviation (RPD) of 3.6-6.1, 2.1-2.7, 1.7-2.9, 1.6-2.6 and 2.5-3.0 for storage time, FAST index, soluble protein, fat and SFF content prediction respectively. Vis-NIR, MIR and Raman were demonstrated to be potential PAT tools for process control and quality assurance applications in infant formula and dairy ingredient manufacture. Copyright © 2018 Elsevier B.V. All rights reserved.

Experimental study of catalytic hydrogenation by using an in-situ hydrogen measuring technique. Final report

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

Chiang, S.H.; Klinzing, G.E.; Cheng, Y.S.

1984-12-01

An in-situ technique for measuring hydrogen concentration (partial pressure) had been previously used to measure static properties (hydrogen solubilities, vapor pressures of hydrocarbons, etc.). Because of its good precision (2% relative error) and relatively short respond time (9.7 to 2.0 seconds at 589 to 728K), the technique was successfully applied to a dynamic study of hydrogenation reactions in this work. Furthermore, the technique is to be tested for industrial uses. Hydrogen/1-methylnaphthalene system was experimentally investigated in a one-liter autoclave equipped with a magnetically driven stirrer and temperature controlling devices. Catalytic hydrogenation of 1-methylnaphthalene was studied in the presence of sulfidedmore » Co-Mo-Al2O3 catalyst. In addition, the vapor/liquid equilibrium relationship was determined by using this technique. Hydrogenation reaction runs were performed at temperatures of 644.1, 658.0 and 672.0K and pressures up to 9.0 MPa. The ring hydrogenation, resulting in 1- and 5-methyltetralin, was found to be the dominant reaction. This is in agreement with cited literature. Effects of hydrogen partial pressure, operating temperature, as well as presulfided catalyst are also investigated and discussed in this work. The vapor pressure of 1-methylnaphthalene was measured over a temperature range of 555.2 to 672.0K. The results are in good agreement with literature data. Measurements for hydrogen solubility in 1-methylnaphthalene were conducted over temperature and pressure range of 598 to 670K and 5.2 to 8.8 MPa, respectively. Similar to previously reported results, the hydrogen solubility increases with increasing temperature when total pressure is held constant. A linear relation is found between the hydrogen solubility and hydrogen partial pressure. 21 refs., 13 figs., 10 tabs.« less

Gas chromatographic measurements of activity coefficients at infinite dilution for refrigerants with a polyol ester oil as a stationary phase

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

Stryjek, R.; Bobbo, S.; Camporese, R.

1999-05-01

Activity coefficients at infinite dilution have been measured by gas chromatography for 14 refrigerants (R12, R22, R32, R124, R125, R134a, R142b, R143a, RE170, R236ea, R290, R600, R600a, and R236fa) as solutes, using a polyol ester oil (POE), EMKARATE by ICI, as a stationary phase (solvent). Instrumental analysis (NMR, IR) showed that the main components of the oil are pentaerithritol esters of carboxylic acids, and electrospray ionization spectrometry revealed an average molecular mass of the POE of 618 g/mol. The measurements were performed within a temperature range of 244 K to 313 K, but a specific temperature range for each refrigerantmore » was adopted depending on its retention data. The experimental findings are well-represented by the equation: ln {gamma}{sub i}{sup {infinity}} = a{sub i} {minus} b{sub i}/T. Some refrigerants, i.e., R22, R124, R125, R236ea, and R236fa, show quite a considerable positive temperature dependence of their activity coefficients at infinite dilution, which can be attributed to hydrogen bonding with the POE, unlike other refrigerants that show a small, either positive or negative temperature dependence. To the authors` knowledge, there are no data in the literature on activity coefficients at infinite dilution for refrigerant and oil (lubricant) systems, and details on the solubility of refrigerants in oils are also extremely scarce.« less

Characterization of digestive enzymes from de-oiled mackerel (Scomber japonicus) muscle obtained by supercritical carbon dioxide and n-hexane extraction as a comparative study.

PubMed

Asaduzzaman, A K M; Chun, Byung-Soo

2015-06-01

The oil in mackerel muscle was extracted using an environmental friendly solvent, supercritical carbon dioxide (SC-CO2) at a semi-batch flow extraction process and an n-hexane. The SC-CO2 was carried out at temperature 45 °C and pressures ranging from 15 to 25 MPa. The flow rate of CO2 (27 g/min) was constant at the entire extraction period of 2 h. The highest oil extracted residues after SC-CO2 extraction was used for activity measurement of digestive enzymes. Four digestive enzymes were found in water soluble extracts after n-hexane and SC-CO2 treated samples. Amylase, lipase and trypsin activities were higher in water soluble extracts after SC-CO2 treated samples except protease. Among the four digestive enzymes, the activity of amylase was highest and the value was 44.57 uM/min/mg of protein. The water soluble extracts of SC-CO2 and n-hexane treated mackerel samples showed same alkaline optimum pH and pH stability for each of the digestive enzymes. Optimum temperature of amylase, lipase, protease and trypsin was 40, 50, 60 and 30 °C, respectively of both extracts. More than 80 % temperature stability of amylase, lipase, protease and trypsin were retained at mentioned optimum temperature in water soluble extracts of both treated samples. Based on protein patterns, prominent protein band showed in water soluble extracts after SC-CO2 treated samples indicates no denaturation of protein than untreated and n-hexane.

Unusual electro-optical behavior in a wide-temperature BPIII cell.

PubMed

Chen, Hui-Yu; Lu, Sheng-Feng; Hsieh, Yi-Chun

2013-04-22

A low driving voltage and fast response blue phase III (BPIII) liquid-crystal device with very low dielectric anisotropy is demonstrated. To stabilize BPIII in a wide temperature range (> 15°C), a chiral molecule with good solubility was chosen. By studying field-dependent polarization state of the transmitting light, it was found that the field-induced birefringence becomes saturated in the high field. However, the transmitting intensity exhibits a tendency to increase as the electric field increases. This indicates that the electro-optical behavior in BPIII device may be from the flexoelectric effect, which induces tilted optical axis and then induces birefringence. Because the phase transition from BPIII to chiral nematic phase does not happen, the device shows no hysteresis effect and no residual birefringence, exhibits fast response, and can be a candidate for fast photonic application.

Solubilization of poorly water-soluble drug carbamezapine in pluronic micelles: effect of molecular characteristics, temperature and added salt on the solubilizing capacity.

PubMed

Kadam, Yogesh; Yerramilli, Usha; Bahadur, Anita

2009-08-01

The solubilization of a poorly water-soluble antiepileptic drug, carbamazepine (CBZ), in a series of micelle-forming PEO-PPO-PEO block copolymers with combinations of blocks having different molecular weight was studied. The drug solubility and micelle-water partition coefficient (P) were determined using UV-vis spectroscopy. Dynamic light scattering on copolymer solutions was used to measure size and polydispersity of nanoaggregates. Solubilization of carbamezapine increased with the rise in temperature and concentration of block copolymers, but no significant increase was observed with added salt (NaCl). The solubilization is also discussed from a thermodynamics viewpoint, by considering the standard free energy of solubilization (DeltaG degrees ).

Solubility of tungsten in a haplobasaltic melt as a function of temperature and oxygen fugacity

NASA Astrophysics Data System (ADS)

Ertel, W.; O'Neill, H. St. C.; Dingwell, D. B.; Spettel, B.

1996-04-01

The solubility of tungsten (W) in a haplobasaltic melt has been determined as a function of oxygen fugacity in the temperature range 1300-1500°C using the mechanically assisted equilibrium technique of Dingwell et al. (1994), and at 1600-1700°C by the wire loop method. Quenched samples were analysed for W by using ICP-AES as well as INAA, and sample major element compositions were checked by electron microprobe. W concentrations ranged from 20 ppm to 17 wt%, and the solution of WO 2 in the melt may be described by Henry's Law up to remarkably high concentrations (e.g., 14 wt% at 1500°C). W dissolves in the melt with a quadrivalent (4+) formal oxidation state over the entire range of oxygen fugacity and temperature investigated. The solubility of W decreases strongly with increasing temperature at constant oxygen fugacity. The solubility data have been used to calculate trace distribution coefficients for W between Fe-rich metal and silicate melt, using literature values for the activity coefficient of W in liquid Fe. Comparison of our data with the distribution coefficients for Mo calculated from the analogous Mo solubility data of Holzheid et al. (1994) shows that the ratio of the metal-silicate distribution coefficient DMomet/sil/ DWmet/sil remains very high (~10 3) at all T-fO 2 conditions. However, in the Earth's mantle, Mo is relatively more depleted than W only by a factor of three. The relative abundances of W and Mo in the Earth's mantle cannot, therefore, be explained by core formation from a homogeneously accreted Earth whatever the temperature at which metal/silicate equilibrium may have ocurred might have been. Their abundances may be quantitatively accounted for by a heterogeneous accretion model such as that of O'Neill (1991).

Modeling solubility and acid-base properties of some amino acids in aqueous NaCl and (CH3)4NCl aqueous solutions at different ionic strengths and temperatures.

PubMed

Bretti, Clemente; Giuffrè, Ottavia; Lando, Gabriele; Sammartano, Silvio

2016-01-01

New potentiometric experiments have been performed in NaCl and in (CH3)4NCl media, to determine the protonation constants, the protonation enthalpy changes and the solubility of six natural α-amino acids, namely Glycine (Gly), Alanine (Ala), Valine (Val), Leucine (Leu), Serine (Ser) and Phenylalanine (Phe). The aim of the work is the rationalization of the protonation thermodynamics (log [Formula: see text], solubility and [Formula: see text]) in NaCl, determining recommended, tentative or provisional values in selected experimental conditions and to report, for the first time, data in a weak interacting medium, as (CH3)4NCl. Literature data analysis was performed selecting the most reliable values, analyzed together with new data here reported. Significant trends and similarities were observed in the behavior of the six amino acids, and in some cases it was possible to determine common parameters for the ionic strength and temperature dependence. In general, the first protonation step, relative to the amino group, is significantly exothermic (average value is [Formula: see text] = -44.5 ± 0.4 kJ mol(-1) at infinite dilution and T = 298.15 K), and the second, relative to the carboxylate group, is fairly close to zero ([Formula: see text] = -2.5 ± 1.6, same conditions). In both cases, the main contribution to the proton binding reaction is mainly entropic in nature. For phenylalanine and leucine, solubility measurements at different concentrations of supporting electrolyte allowed to determine total and specific solubility values, then used to obtain the Setschenow and the activity coefficients of all the species involved in the protonation equilibria. The values of the first protonation constant in (CH3)4NCl are lower than the corresponding values in NaCl, due to the weak interaction between the deprotonated amino group and (CH3)4N(+). In this light, differences between the protonation functions in NaCl and (CH3)4NCl were used for the quantification of the stability of the weak [(CH3)4N(+)-L(-)] complexes that resulted log K = -0.38 ± 0.07 as an average value for the six amino acids.

Introducing litter quality to the ecosystem model LPJ-GUESS: Effects on short- and long-term soil carbon dynamics

NASA Astrophysics Data System (ADS)

Portner, Hanspeter; Wolf, Annett; Rühr, Nadine; Bugmann, Harald

2010-05-01

Many biogeochemical models have been applied to study the response of the carbon cycle to changes in climate, whereby the process of carbon uptake (photosynthesis) has usually gained more attention than the equally important process of carbon release by respiration. The decomposition of soil organic matter is driven by a combination of factors like soil temperature, soil moisture and litter quality. We have introduced dependence on litter substrate quality to heterotrophic soil respiration in the ecosystem model LPJ-GUESS [Smith et al.(2001)]. We were interested in differences in model projections before and after the inclusion of the dependency both in respect to short- and long-term soil carbon dynamics. The standard implementation of heterotrophic soil respiration in LPJ-GUESS is a simple carbon three-pool model whose decay rates are dependent on soil temperature and soil moisture. We have added dependence on litter quality by coupling LPJ-GUESS to the soil carbon model Yasso07 [Tuomi et al.(2008)]. The Yasso07 model is based on an extensive number of measurements of litter decomposition of forest soils. Apart from the dependence on soil temperature and soil moisture, the Yasso07 model uses carbon soil pools representing different substrate qualities: acid hydrolyzable, water soluble, ethanol soluble, lignin compounds and humus. Additionally Yasso07 differentiates between woody and non-woody litter. In contrary to the reference implementation of LPJ-GUESS, in the new model implementation, the litter now is divided according to its specific quality and added to the corresponding soil carbon pool. The litter quality thereby differs between litter source (leaves, roots, stems) and plant functional type (broadleaved, needleleaved, grass). The two contrasting model implementations were compared and validated at one specific CarboEuropeIP site (Lägern, Switzerland) and on a broader scale all over Switzerland. Our focus lay on the soil respiration for the years 2006 and 2007 [Rühr(2009)] and present soil carbon stocks [Heim et al.(2009)]. Our Results show, that for short-term soil carbon dynamics, e.g. estimates of heterotrophic soil respiration on an annual basis, the inclusion of the dependency on litter quality is not necessary, as the differences are minor only. However, when considering long-term soil carbon dynamics, e.g. simulated estimates of present soil carbon content, the dependency on litter quality shows effect, as there are correlations with specific site factors such as site location and forest type. The inclusion of the dependence on litter quality therefore may be of importance for the projection of future soil carbon dynamics, as forest types may well be altered due to climatic change. References [Heim et al.(2009)] A. Heim, L. Wehrli, W. Eugster, and M.W.I. Schmidt. Effects of sampling design on the probability to detect soil carbon stock changes at the swiss CarboEurope site Lägeren. Geoderma, 149(3-4):347-354, 2009. [Rühr(2009)] Nadine Katrin Rühr. Soil respiration in a mixed mountain forest : environmental drivers and partitioning of component fluxes. PhD thesis, ETH, 2009. [Smith et al.(2001)] Benjamin Smith, I. Colin Prentice, and Martin T. Sykes. Representation of vegetation dynamics in the modelling of terrestrial ecosystems: comparing two contrasting approaches within european climate space. Global Ecology and Biogeography, 10(6):621-637, 2001. [Tuomi et al.(2008)] Mikko Tuomi, Pekka Vanhala, Kristiina Karhu, Hannu Fritze, and Jari Liski. Heterotrophic soil respiration-Comparison of different models describing its temperature dependence. Ecological Modelling, 211(1-2): 182-190, 2008.

Solubility of nitrogen in marine mammal blubber depends on its lipid composition.

PubMed

Koopman, Heather N; Westgate, Andrew J

2012-11-01

Understanding the solubility of nitrogen gas in tissues is a crucial aspect of diving physiology, especially for air-breathing tetrapods. Adipose tissue is of particular interest because of the high solubility of nitrogen in lipids. Surprisingly, nothing is known about nitrogen solubility in the blubber of any marine mammal. We tested the hypothesis that N(2) solubility is dependent on the lipid composition of blubber; most blubber is composed of triacylglycerols, but some toothed whales deposit large amounts of waxes in blubber instead. The solubility of N(2) in the blubber of 13 toothed whale species ranged from 0.062 to 0.107 ml N(2) ml(-1) oil. Blubber with high wax ester content had higher N(2) solubility, observed in the beaked (Ziphiidae) and small sperm (Kogiidae) whales, animals that routinely make long, deep dives. We also measured nitrogen solubility in the specialized cranial acoustic fat bodies associated with echolocation in a Risso's dolphin; values (0.087 ml N(2) ml(-1) oil) were 16% higher here than in its blubber (0.074 ml N(2) ml(-1) oil). As the acoustic fats of all Odontocetes contain waxes, even if the blubber does not, these tissues may experience greater interaction with N(2). These data have implications for our understanding and future modeling of diving physiology in Odontocetes, as our empirically derived values for nitrogen solubility in toothed whale adipose were up to 40% higher than the numbers traditionally assumed in marine mammal diving models.

Effect of high molecular weight plasticizers on the gelatinization of starch under static and shear conditions.

PubMed

Taghizadeh, Ata; Favis, Basil D

2013-02-15

Starch gelatinization in the presence of high molecular weight polyol plasticizers and water was studied under static and dynamic conditions and was compared to a glycerol reference. For static gelatinization, glycerol, sorbitol, diglycerol and polyglycerol were examined using polarized light microscopy and differential scanning calorimetry. A wide range of starch/water/plasticizer compositions were prepared to explore the gelatinization regime for each plasticizer. The plasticizers show that the onset and conclusion temperatures for sorbitol and glycerol are in the same range and are lower than the other two plasticizers. On the other hand, polyglycerol shows a higher gelatinization temperature than diglycerol because of its higher molecular weight and viscosity. The results indicate that in the case of all plasticizers, increasing the water content tends to decrease the gelatinization temperature and, except for polyglycerol, increasing the plasticizer content increases the gelatinization temperature. In the case of polyglycerol, however, increasing the plasticizer content had the opposite effect and this was found to be related to the borderline solubility of polyglycerol in water. When the polyglycerol/water solubility was increased by increasing the temperature of the water/plasticizer/starch slurry, the gelatinization temperature dependence was found to be similar to the other polyols. A rheological technique was developed to study the dynamic gelatinization process by tracking the influence of shear on the complex viscosity in a couette flow system. Glycerol, diglycerol and sorbitol were subjected to different dynamic gelatinization treatments and the results were compared with static gelatinization. It is quantitatively shown that shear has a major effect on the gelatinization process. The conclusion temperature of gelatinization is significantly diminished (up to 21 °C) in the presence of shear whereas the onset temperature of gelatinization remains virtually unchanged as compared to static conditions. By comparing glycerol, diglycerol and sorbitol data, it is shown that the molecular weight or structure did not qualitatively affect the changes shear imposed on dynamic gelatinization. Shear had a relatively more pronounced effect on diglycerol as the plasticizer with less hydrogen bonding ability. Copyright © 2012 Elsevier Ltd. All rights reserved.

The addition of iodine to tetramethylammonium iodide

USGS Publications Warehouse

Foote, H.W.; Fleischer, M.

1953-01-01

The system tetramethylammonium iodide-iodine-toluene has been studied by the solubility method at 6 and at 25??. The compounds (CH3)4NI3, (CH3)4NI5 and (CH3)4NI11 were found to be stable phases at both temperatures. In addition, the compound (CH3)4NI10 was found at 6?? and the compound (CH3)4NI9 at 25??. The dissociation pressures of the compounds at these temperatures were calculated from the solubility data.

Cavity Ring Down and Thermal Lens Techniques Applied to Vibrational Spectroscopy of Gases and Liquids

NASA Astrophysics Data System (ADS)

Nyaupane, Parashu Ram

Infrared (IR) and near-infrared (NIR) region gas temperature sensors have been used in the past because of its non-intrusive character and fast time response. In this dissertation cavity ring down (CRD) absorption of oxygen around the region 760 nm has been used to measure the temperature of flowing air in an open optical cavity. This sensor could be a convenient method for measuring the temperature at the input (cold air) and output (hot air) after cooling the blades of a gas turbine. The results could contribute to improvements in turbine blade cooling designs. Additionally, it could be helpful for high temperature measurement in harsh conditions like flames, boilers, and industrial pyrolysis ovens as well as remote sensing. We are interested in experiments that simulate the liquid methane and ethane lakes on Titan which is around the temperature of 94 K. Our specific goal is to quantify the solubility of unsaturated hydrocarbons in liquid ethane and methane. However, it is rather complicated to do so because of the low temperatures, low solubility and solvent effects. So, it is wise to do the experiments at higher temperature and test the suitability of the techniques. In these projects, we were trying to explore if our existing laboratory techniques were sensitive enough to obtain the solubility of unsaturated hydrocarbons in liquid ethane. First, we studied the thermal lens spectroscopy (TLS) of the (Deltav = 6) C-H overtone of benzene and naphthalene in hexane and CCl4 at room temperature.

A model for studying the composition and chemical effects of stratospheric aerosols

NASA Technical Reports Server (NTRS)

Tabazadeh, Azadeh; Turco, Richard P.; Jacobson, Mark Z.

1994-01-01

We developed polynomial expressions for the temperature dependence of the mean binary and water activity coefficients for H2SO4 and HNO3 solutions. These activities were used in an equilibrium model to predict the composition of stratospheric aerosols under a wide range of environmental conditions. For typical concentrations of H2O, H2SO4, HNO3, HCl, HBr, HF, and HOCl in the lower stratosphere, the aerosol composition is estimated as a function of the local temperature and the ambient relative humidity. For temperatures below 200 K, our results indicate that (1) HNO3 contributes a significant mass fraction to stratospheric aerosols, and (2) HCl solubility is considerably affected by HNO3 dissolution into sulfate aerosols. We also show that, in volcanically disturbed periods, changes in stratospheric aerosol composition can significantly alter the microphysics that leads to the formation of polar stratospheric clouds. The effects caused by HNO3 dissolution on the physical and chemical properties of stratospheric aerosols are discussed.

The measurement of sulfate mineral solubilities in the Na-K-Ca-Cl-SO 4-H 2O system at temperatures of 100, 150 and 200°C

NASA Astrophysics Data System (ADS)

Freyer, Daniela; Voigt, Wolfgang

2004-01-01

At T > 100°C development of thermodynamic models suffers from missing experimental data, particularly for solubilities of sulfate minerals in mixed solutions. Solubilities in Na +-K +-Ca 2+-Cl --SO 42-/H 2O subsystems were investigated at 150, 200°C and at selected compositions at 100°C. The apparatus used to examine solid-liquid phase equilibria under hydrothermal conditions has been described. In the system NaCl-CaSO 4-H 2O the missing anhydrite (CaSO 4) solubilities at high NaCl concentrations up to halite saturation have been determined. In the system Na 2SO 4-CaSO 4-H 2O the observed glauberite (Na 2SO 4 · CaSO 4) solubility is higher than that predicted by the high temperature model of Greenberg and Møller (1989), especially at 200°C. At high salt concentrations, solubilities of both anhydrite and glauberite increase with increasing temperature. Stability fields of the minerals syngenite (K 2SO 4 · CaSO 4 · H 2O) and goergeyite (K 2SO 4 · 5 CaSO 4 · H 2O) were determined, and a new phase was found at 200°C in the K 2SO 4-CaSO 4-H 2O system. Chemical and single crystal structure analysis give the formula K 2SO 4 · CaSO 4. The structure is isostructural with palmierite (K 2SO 4 · PbSO 4). The glaserite ("3 K 2SO 4 · Na 2SO 4") appears as solid solution in the system Na 2SO 4-K 2SO 4-H 2O. Its solubility and stoichiometry was determined as a function of solution composition.

Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

PubMed

Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

2012-09-30

This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

UDP-glucose:glycoprotein glucosyltransferase (UGGT1) promotes substrate solubility in the endoplasmic reticulum

PubMed Central

Ferris, Sean P.; Jaber, Nikita S.; Molinari, Maurizio; Arvan, Peter; Kaufman, Randal J.

2013-01-01

Protein folding in the endoplasmic reticulum (ER) is error prone, and ER quality control (ERQC) processes ensure that only correctly folded proteins are exported from the ER. Glycoproteins can be retained in the ER by ERQC, and this retention contributes to multiple human diseases, termed ER storage diseases. UDP-glucose:glycoprotein glucosyltransferase (UGGT1) acts as a central component of glycoprotein ERQC, monoglucosylating deglucosylated N-glycans of incompletely folded glycoproteins and promoting subsequent reassociation with the lectin-like chaperones calreticulin and calnexin. The extent to which UGGT1 influences glycoprotein folding, however, has only been investigated for a few selected substrates. Using mouse embryonic fibroblasts lacking UGGT1 or those with UGGT1 complementation, we investigated the effect of monoglucosylation on the soluble/insoluble distribution of two misfolded α1-antitrypsin (AAT) variants responsible for AAT deficiency disease: null Hong Kong (NHK) and Z allele. Whereas substrate solubility increases directly with the number of N-linked glycosylation sites, our results indicate that additional solubility is conferred by UGGT1 enzymatic activity. Monoglucosylation-dependent solubility decreases both BiP association with NHK and unfolded protein response activation, and the solubility increase is blocked in cells deficient for calreticulin. These results suggest that UGGT1-dependent monoglucosylation of N-linked glycoproteins promotes substrate solubility in the ER. PMID:23864712

Solubility of copper in silicate melts as function of oxygen and sulfur fugacities, temperature, and silicate composition

NASA Astrophysics Data System (ADS)

Holzheid, A.; Lodders, K.

2001-06-01

The solubility of Cu in silicate melts coexisting with liquid Cu(Fe) metal and liquid Cu(Fe) sulfide was determined experimentally at oxygen fugacities ranging from 10 -9.1 to 10 -13.6 bar and sulfur fugacities ranging from 10 -2.5 to 10 -6.3 bar at 1300°C. An iron oxide-free silicate of anorthite-diopside eutectic composition and a synthetic MgO-rich basaltic silicate (FeO-bearing) were used in the partitioning experiments. In S-containing systems, some of the metal reacted to metal sulfide. The silicates in the four systems investigated (Fe-free and S-free; Fe-containing and S-free; Fe-free and S-containing; Fe-containing and S-containing) had different colors depending on the dissolved Cu species and the presence of iron and/or sulfur. Irrespective of the presence of sulfur, the solubility of Cu in the silicate increases with increasing oxygen fugacity and metal/silicate partition coefficients for Cu decrease. Increasing the temperature from 1300°C to 1514°C increases the Cu solubility (decreases the metal/silicate partition coefficient) at an oxygen fugacity 0.5 log units below the iron-wüstite (IW) equilibrium in the Fe-free, S-free and Fe-containing, S-free systems. We infer the presence of monovalent Cu + ("CuO 0.5") in the silicate melt on the basis of the solubility of Cu as function of oxygen fugacity. Experiments containing iron yield a formal valence of ˜0.5 for Cu at very low oxygen fugacities, which is not observed in Fe-free systems. The low formal valence is explained by redox reactions between iron and copper in the silicate melts. There is no evidence for sulfidic dissolution of Cu in the silicates but sulfur has indirect effects on Cu partitioning. Iron metal/silicate partition coefficients depend on oxygen fugacity and on sulfur fugacity. Sulfidic dissolution of iron and oxide-sulfide exchange reactions with Cu cause a small increase in Cu metal/silicate partition coefficients. We derive an activity coefficient (γ CuO 0.5) of 10 ± 1 for liquid CuO 0.5 at 1300°C for the silicate melts used here. A comparison with literature data shows that log γ CuO 0.5 increases in proportion to the mass percentages [CaO +(Al 2O 3)/2] in silicate melts. We recommend the following equations for Cu metal/silicate and sulfide/silicate partitioning for geochemical and cosmochemical modeling if silicate composition and the activity of Cu in the metal or sulfide is known: log D met/sil = -0.48 - 0.25 · log fO 2 - log γ Cu metal + 0.02 · [CaO + (Al 2O 3)/2; wt%] silicate logD sul/sil=+0.76-0.25 · logfO 2+0.25logfS 2-logγ CS 0.5,sulfide +0.02 · [CaO+Al 2O 3/2;wt%] silicate. The derived Cu metal/silicate and metal/sulfide partition coefficients are applied to core formation in the Earth and Mars. The observed Cu abundances in the Earth cannot be easily explained by simple core-mantle equilibrium, but the observed Cu abundances for Mars are consistent with core-mantle equilibrium at low pressure and temperatures.

Correlation of published data on the solubility of methane in H/sub 2/O-NaCl solutions

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

Coco, L.T.; Johnson, A.E. Jr.; Bebout, D.G.

1981-01-01

A new correlation of the available published data for the solubility of methane in water was developed, based on fundamental thermodynamic relationships. An empirical relationship for the salting-out coefficient of NaCl for methane solubility in water was determined as a function of temperature. Root mean square and average deviations for the new correlation, the Haas correlation, and the revised Blount equation are compared.

[Changes in blood gases with temperature: implications for clinical practice].

PubMed

Tremey, B; Vigué, B

2004-05-01

To understand changes in blood gases results with core temperature. Analysis from two case reports. Hypothermia induces a decrease in PaCO(2) with a related increase in pH, thus a physiologic alkalosis. Decrease in PaCO(2) is due to an increase of gas solubility and a decrease of peripheral consumption that can be estimated from comparison between corrected and non-corrected for temperature blood gases. For O(2), variations of temperature induce variations of solubility but also of haemoglobin affinity for O(2). During hyperthermia, haemoglobin affinity for O(2) is decreased with a decreased SvO(2) for a same PvO(2). SvO(2) ischemic or therapeutic thresholds are thus modified with core temperature. Blood gases cannot be understood without patient core temperature. Physiologic variations of PaCO(2) and pH must probably be tolerated. Ischemic threshold should be estimated on PvO(2), not only on PvO(2).

On the Role of Dissolved Gases in the Atmosphere Retention of Low-mass Low-density Planets

NASA Astrophysics Data System (ADS)

Chachan, Yayaati; Stevenson, David J.

2018-02-01

Low-mass low-density planets discovered by Kepler in the super-Earth mass regime typically have large radii for their inferred masses, implying the presence of H2–He atmospheres. These planets are vulnerable to atmospheric mass loss due to heating by the parent star’s XUV flux. Models coupling atmospheric mass loss with thermal evolution predicted a bimodal distribution of planetary radii, which has gained observational support. However, a key component that has been ignored in previous studies is the dissolution of these gases into the molten core of rock and iron that constitute most of their mass. Such planets have high temperatures (>2000 K) and pressures (∼kbars) at the core-envelope boundary, ensuring a molten surface and a subsurface reservoir of hydrogen that can be 5–10 times larger than the atmosphere. This study bridges this gap by coupling the thermal evolution of the planet and the mass loss of the atmosphere with the thermodynamic equilibrium between the dissolved H2 and the atmospheric H2 (Henry’s law). Dissolution in the interior allows a planet to build a larger hydrogen repository during the planet formation stage. We show that the dissolved hydrogen outgasses to buffer atmospheric mass loss. The slow cooling of the planet also leads to outgassing because solubility decreases with decreasing temperature. Dissolution of hydrogen in the interior therefore increases the atmosphere retention ability of super-Earths. The study highlights the importance of including the temperature- and pressure-dependent solubility of gases in magma oceans and coupling outgassing to planetary evolution models.

Molecular Simulation of Gas Solubility in Nitrile Butadiene Rubber.

PubMed

Khawaja, M; Sutton, A P; Mostofi, A A

2017-01-12

Molecular simulation is used to compute the solubility of small gases in nitrile butadiene rubber (NBR) with a Widom particle-insertion technique biased by local free volume. The convergence of the method is examined as a function of the number of snapshots upon which the insertions are performed and the number of insertions per snapshot and is compared to the convergence of the unbiased Widom insertion technique. The effect of varying the definition of local free volume is also investigated. The acrylonitrile content of the polymer is altered to examine its influence on the solubility of helium, CO 2 , and H 2 O, and the solubilities of polar gases are found to be enhanced relative to those of nonpolar gases, in qualitative agreement with experiment. To probe this phenomenon further, the solubilities are decomposed into contributions from the neighborhoods of different atoms, using a Voronoi cell construction, and a strong bias is found for CO 2 and H 2 O in particular to be situated near nitrogen sites in the elastomer. Temperature is shown to suppress the solubility of CO 2 and H 2 O but to increase that of helium. Increasing pressure is found to suppress the solubility of all gases but at different rates, according to a balance between their molecular sizes and electrostatic interactions with the polymer. These results are relevant to the use of NBR seals at elevated temperatures and pressures, such as in oil and gas wells.

APPLICATION OF VARIOUS POLYMERS AND POLYMERS BASED TECHNIQUES USED TO IMPROVE SOLUBILITY OF POORLY WATER SOLUBLE DRUGS: A REVIEW.

PubMed

Muhammad Sarfraz, Rai; Bashir, Sajid; Mahmood, Asif; Ahsan, Haseeb; Riaz, Humayun; Raza, Hina; Rashid, Zermina; Atif Raza, Syed; Asad Abrar, Muhammad; Abbas, Khawar; Yasmeen, Tahira

2017-03-01

Solubility is concerned with solute and solvent to form a homogenous mixture. If solubility of a drug is low, then usually it is difficult to achieve desired therapeutic level of drug. Most of the newly developed entities have solubility problems and encounter difficulty in dissolution. Basic aim of solubility enhancement is to achieve desired therapeutic'level of drug to produce required pharmacological response. Different techniques are being used to enhance the solubility of water insoluble drugs. These techniques include particle size reduction, spray drying, kneading method, solvent evaporation method, salt formation, microemulsions, co-solven- cy, hydrosols, prodrug approach, supercritical fluid process, hydrogel micro particles etc. Selection of solubility improving method depends on drug properties, site of absorption, and required dosage form characteristics. Variety of polymers are also used to enhance solubility of these drugs like polyethylene glycol 300, polyvinyl pyrrolidone, chitosan, β-cyclodextrins etc.

Thermo-mechanical mechanism of laser-assisted alteration and stabilization of micro pore structure in eye-sclera

NASA Astrophysics Data System (ADS)

Baum, Olga; Wachsmann-Hogiu, Sebastian; Sobol, Emil

2018-02-01

Thermo-mechanical effect of laser radiation is a basis of new method of normalization of intraocular pressure in glaucomatous eyes due to laser-assisted pore formation in eye sclera. Laser-induced creation of pores in sclera increases hydraulic permeability. Stability of laser-induced pore system is achieved via gas nano-bubbles arisen in the sclera under laser radiation as a result of temperature dependency of gas solubility. The stabilization of laser-induced gas and pore systems in the tissue is an important mechanism for a long lasting healing of glaucoma observed in clinical trials with one year follow-up.

Quantum chemical approach for condensed-phase thermochemistry (IV): Solubility of gaseous molecules

NASA Astrophysics Data System (ADS)

Ishikawa, Atsushi; Kamata, Masahiro; Nakai, Hiromi

2016-07-01

The harmonic solvation model (HSM) was applied to the solvation of gaseous molecules and compared to a procedure based on the ideal gas model (IGM). Examination of 25 molecules showed that (i) the accuracy of ΔGsolv was similar for both methods, but the HSM shows advantages for calculating ΔHsolv and TΔSsolv; (ii) TΔSsolv contributes more than ΔHsolv to ΔGsolv in the HSM, i.e. the solvation of gaseous molecules is entropy-driven, which agrees well with experimental understanding (the IGM does not show this); (iii) the temperature dependence of Henry's law coefficient was correctly reproduced with the HSM.

Miscibility, solubility, viscosity, and density measurements for R-236ea with four different Exxon lubricants. Final report, March 1995-March 1997

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

Kang, H.M.; Pate, M.B.

1999-06-15

The report discusses miscibility, solubility, viscosity, and density data for the refrigerant hydrofluorocarbon (HFC)-236ea (or R-236ea) and four lubricants supplied by Exxon Corporation. The miscibility tests were performed in a test facility consisting of a series of miniature test cells submerged in a constant temperature bath, precisely controlled over a range of {minus}50 to 90 C. Critical solution temperatures obtained from the miscibility data are presented for each refrigerant/lubricant combination. Data for the R-236ea in each of the test lubricants have been collected for refrigerant concentrations of 10--90%. The raw data have been presented, and the results have been summarized.more » Solubility, viscosity, and density data were also obtained for R-236ea mixed with the same four oils for a refrigerant concentration range of 0--40 wt% refrigerant over a temperature range of 30--100 C.« less

Solubility of uranium oxide in molten salt electrolysis bath of LiF-BaF2 with LaF3 additive

NASA Astrophysics Data System (ADS)

Alangi, Nagaraj; Mukherjee, Jaya; Gantayet, L. M.

2016-03-01

The solubility of UO2 in the molten mixtures of equimolar LiF-BaF2(1:1) with LaF3 as additive was studied in the range of 1423 K-1523 K. The molten fluoride salt mixture LiF-BaF2 LaF3 was equilibrated with a sintered uranium oxide pellet at 1423 K, 1473 K, 1523 K and the salt samples were collected after equilibration. Studies were conducted in the range of 10%-50% by weight additions of LaF3 in the equimolar LiF-BaF2(1:1) base fluoride salt bath. Solubility of UO2 increased with rise in LaF3 concentration in the molten fluoride in the temperature range of 1423 K-1523 K. At a given concentration of LaF3, the UO2 solubility increased monotonously with temperature. With mixed solvent, when UF4 was added as a replacement of part of LaF3 in LiF-BaF2(1:1)-10 wt% LaF3 and LiF-BaF2(1:1)-30 wt% LaF3, there was an enhancement of solubility of UO2.

Water-Soluble Epitaxial NaCl Thin Film for Fabrication of Flexible Devices.

PubMed

Lee, Dong Kyu; Kim, Sungjoo; Oh, Sein; Choi, Jae-Young; Lee, Jong-Lam; Yu, Hak Ki

2017-08-18

We studied growth mechanisms of water-soluble NaCl thin films on single crystal substrates. Epitaxial growth of NaCl(100) on Si(100) and domain-matched growth of NaCl(111) on c-sapphire were obtained at thicknesses below 100 nm even at room temperature from low lattice mismatches in both cases. NaCl thin film, which demonstrates high solubility selectivity for water, was successfully applied as a water-soluble sacrificial layer for fabrication of several functional materials, such as WO 3 nano-helix and Sn doped In 2 O 3 nano-branches.

Investigation of factors affecting in vitro doxorubicin release from PEGylated liposomal doxorubicin for the development of in vitro release testing conditions.

PubMed

Shibata, Hiroko; Izutsu, Ken-Ichi; Yomota, Chikako; Okuda, Haruhiro; Goda, Yukihiro

2015-01-01

Establishing appropriate drug release testing methods of liposomal products for assuring quality and performance requires the determination of factors affecting in vitro drug release. In this study, we investigated the effects of test conditions (human plasma lot, pH/salt concentration in the test media, dilution factor, temperature, ultrasound irradiation, etc.), and liposomal preparation conditions (pH/concentration of ammonium sulfate solution), on doxorubicin (DXR) release from PEGylated liposomal DXR. Higher temperature and lower pH significantly increased DXR release. The evaluation of DXR solubility indicated that the high DXR release induced by low pH may be attributed to the high solubility of DXR at low pH. Ultrasound irradiation induced rapid DXR release in an amplitude-dependent manner. The salt concentration in the test solution, human plasma lot, and dilution factor had a limited impact on DXR-release. Variations in the ammonium sulfate concentration used in solutions for the formation/hydration of liposomes significantly affected DXR release behavior, whereas differences in pH did not. In addition, heating condition in phosphate-buffered saline at lower pH (<6.5) exhibited higher discriminative ability for the release profiles from various liposomes with different concentrations of ammonium sulfate than did ultrasound irradiation. These results are expected to be helpful in the process of establishing appropriate drug release testing methods for PEGylated liposomal DXR.

Paraequilibrium Carburization of Duplex and Ferritic Stainless Steels

NASA Astrophysics Data System (ADS)

Michal, G. M.; Gu, X.; Jennings, W. D.; Kahn, H.; Ernst, F.; Heuer, A. H.

2009-08-01

AISI 301 and E-BRITE stainless steels were subjected to low-temperature (743 K) carburization experiments using a commercial technology developed for carburization of 316 austenitic stainless steels. The AISI 301 steel contained ~40 vol pct ferrite before carburization but had a fully austenitic hardened case, ~20- μm thick, and a surface carbon concentration of ~8 at. pct after treatment; this “colossal” paraequilibrium carbon supersaturation caused an increase in lattice parameter of ~3 pct. The E-BRITE also developed a hardened case, 12- to 18- μm thick, but underwent a more modest (~0.3 pct) increase in lattice parameter; the surface carbon concentration was ~10 at. pct. While the hardened case on the AISI 301 stainless steel appeared to be single-phase austenite, evidence for carbide formation was apparent in X-ray diffractometer (XRD) scans of the E-BRITE. Paraequilibrium phase diagrams were calculated for both AISI 301 and E-BRITE stainless steels using a CALPHAD compound energy-based interstitial solid solution model. In the low-temperature regime of interest, and based upon measured paraequilibrium carbon solubilities, more negative Cr-carbon interaction parameters for austenite than those in the current CALPHAD data base may be appropriate. A sensitivity analysis involving Cr-carbon interaction parameters for ferrite found a strong dependence of carbon solubility on relatively small changes in the magnitude of these parameters.

Effect of muscle type, salt and pH on cooked meat haemoprotein formation in lamb and beef.

PubMed

Lytras, G N; Geileskey, A; King, R D; Ledward, D A

1999-06-01

The rate of cooked meat haemoprotein formation, measured as the rate of loss of myoglobin solubility, in lamb was dependent on the muscles anatomical location and temperature. Lamb longissimus dorsi musle at 55 to 70°C formed cooked meat haemoprotein more rapidly than the muscles in the shoulder and leg. The formation in lamb was more rapid than in beef. The rate in high pH beef (7.25) l. dorsi was lower than found in beef l. dorsi of normal pH but in low pH lamb (5.38) l. dorsi the rate was, at most temperatures, also slower than found in this muscle from lamb of normal pH. In the presence of NaCl the rate of cooked meat haemoprotein formation was faster (almost doubled at 2g/100g meat) than found in the corresponding salt free lamb and beef samples. Other additives commonly added to meat products (mechanically recovered meat, oil, polyphosphates, soya, whey and caseinate) had little effect on the rate of cooked meat haemoprotein formation, at the levels normally used in meat products. It is concluded that for lamb products little if any myoglobin will remain soluble, and the products will look cooked before the recommended thermal treatment to inactivate Escherichia coli O157:H7 has been achieved. ©

The microbial transglutaminase immobilization on carboxylated poly(N-isopropylacrylamide) for thermo-responsivity.

PubMed

Zhou, Jian Qin; He, Ting; Wang, Jian Wen

2016-06-01

Microbial transglutaminase (mTG) is widely utilized in the PEGylation of pharmaceutical proteins. mTG immobilization can be achieved via covalent bonding on solid supports. However, the catalytic efficiency of mTG immobilized on solid supports was significantly reduced by mass transfer limitation. To overcome this limitation, mTG was covalently immobilized on the thermo-responsive carboxylated poly(N-isopropylacrylamide) (pNIPAM). The pNIPAM-mTG conjugate exhibited reversibly solubility in aqueous solution with a low critical solution temperature (LCST) at 39°C, i.e., it was insoluble above 39°C and soluble below 39°C. The pH dependence of the pNIPAM-mTG conjugate was similar with that of the native mTG. Upon conjugation to pNIPAM, the optimal temperature of mTG shifted down from 50-55°C to 40-45°C, and the thermal stability of the conjugate was elevated. The easy separation of the pNIPAM-mTG conjugate with its substrate and the catalytic efficiency of the pNIPAM-mTG conjugate were demonstrated by employing the pNIPAM-mTG conjugate to cross-link bovine serum albumin (BSA) and catalyze PEGylation of therapeutic protein, cytochrome c (Cyt C), respectively. The thermo-responsive mTG is suitable to modify proteins in food processing and biomedical engineering. Copyright © 2016 Elsevier Inc. All rights reserved.

Solid state stability and solubility of triethylenetetramine dihydrochloride.

PubMed

Henriet, Théo; Gana, Inès; Ghaddar, Carine; Barrio, Maria; Cartigny, Yohann; Yagoubi, Najet; Do, Bernard; Tamarit, Josep-Lluis; Rietveld, Ivo B

2016-09-10

The API triethylenetetramine dihydrochloride used as an alternative treatment of Wilson's disease is sensitive to water and it exhibits polymorphism. As this may become an issue for the drug formulation, the physical stability has been studied by differential scanning calorimetry, high-pressure thermal analysis, dynamic vapor sorption, and X-ray diffraction as a function of temperature. In addition, high-pressure liquid chromatography and mass spectrometry have been used to study the purity and chemical stability of the API. A pressure-temperature phase diagram of the pure compound has been constructed and it can be concluded that form II is monotropic in relation to form I, which is the only stable solid. The solubilities of the different solid forms have been determined with the help of a temperature - composition phase diagram. The API is very soluble, at 20° C about 10% of the saturated solution with respect to the dihydrate consists of API and the solubility of the pure form I is twice as high. Moreover, it has been shown that at 20°C, a relative humidity above 40% induces the formation of the dihydrate and at 70% a saturated solution appears. At higher temperatures, the formation of the dihydrate appears at lower relative humidity values. A clear link has been established between the API's chemical stability, its physical stability and the relative humidity in the air. Humidity levels above 40% are detrimental to the quality of the API. Copyright © 2016 Elsevier B.V. All rights reserved.

Solubility of carbon dioxide in aqueous solutions of 2-amino-2-methyl-1-propanol and N-methyldiethanolamine and their mixtures in the temperature range of 313 to 353 K and pressures up to 2.7 MPa

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

Silkenbaeumer, D.; Lichtenthaler, R.N.; Rumpf, B.

1998-08-01

The solubility of carbon dioxide in aqueous solutions containing 2-amino-2-methyl-1-propanol (AMP) was measured in the temperature range from 313 to 353 K at total pressures up to 2.7 MPa using an analytical method. A model taking into account chemical reactions in the liquid phase as well as physical interactions is used to correlate the new data. To test the predictive capability of the model, the solubility of carbon dioxide in an aqueous solution containing AMP and N-methyldiethanolamine (MDEA) was measured at 313 K. Experimental results are reported and compared to literature data and calculations.

Measuring Compartment Size and Gas Solubility in Marine Mammals

DTIC Science & Technology

2015-09-30

Koopman, H.N. and A.J. Westgate, Solubility of nitrogen in marine mammal blubber depends on its lipid composition. Journal of Experimental Biology ...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Measuring Compartment Size and Gas Solubility in Marine ...Mammals Michael Moore Biology Department Woods Hole Oceanographic Institution Woods Hole, MA 02543 phone: (508) 289-3228 fax: (508) 457

Solubility of polyethers in hydrocarbons at low temperatures. A model for potential genetic backbones on warm titans.

PubMed

McLendon, Christopher; Opalko, F Jeffrey; Illangkoon, Heshan I; Benner, Steven A

2015-03-01

Ethers are proposed here as the repeating backbone linking units in linear genetic biopolymers that might support Darwinian evolution in hydrocarbon oceans. Hydrocarbon oceans are found in our own solar system as methane mixtures on Titan. They may be found as mixtures of higher alkanes (propane, for example) on warmer hydrocarbon-rich planets in exosolar systems ("warm Titans"). We report studies on the solubility of several short polyethers in propane over its liquid range (from 85 to 231 K, or -188 °C to -42 °C). These show that polyethers are reasonably soluble in propane at temperatures down to ca. 200 K. However, their solubilities drop dramatically at still lower temperatures and become immeasurably low below 170 K, still well above the ∼ 95 K in Titan's oceans. Assuming that a liquid phase is essential for any living system, and genetic biopolymers must dissolve in that biosolvent to support Darwinism, these data suggest that we must look elsewhere to identify linear biopolymers that might support genetics in Titan's surface oceans. However, genetic molecules with polyether backbones may be suitable to support life in hydrocarbon oceans on warm Titans, where abundant organics and environments lacking corrosive water might make it easier for life to originate.

IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 2. Light Lanthanides (Ce-Eu)

NASA Astrophysics Data System (ADS)

Mioduski, Tomasz; Gumiński, Cezary; Zeng, Dewen

2015-03-01

This is the second part of the volume devoted to the evaluation of experimental solubility data for rare earth metal (REM) fluorides in water as well as in aqueous ternary and multicomponent systems. Fluorides of Ce, Pr, Nd, Pm, Sm, and Eu (so-called light lanthanides), as the main solutes, are covered in the present part, which has thorough coverage of the experimental literature through the end of 2012. The experimentally unknown solubility value for PmF3 in water was predicted by an interpolation of the solubility values for NdF3 and SmF3 at 298 K. General features of the systems, such as the nature of the equilibrium solid phases, solubility as a function of temperature, influence of ionic strength, pH, mixed solvent medium on the solubility, quality of the solubility results, and solubility as a function of REM atomic number, have already been presented in Part 1 of the volume.

Water sorption in microfibrillated cellulose (MFC): The effect of temperature and pretreatment.

PubMed

Meriçer, Çağlar; Minelli, Matteo; Giacinti Baschetti, Marco; Lindström, Tom

2017-10-15

Water sorption behavior of two different microfibrillated cellulose (MFC) films, produced by delamination of cellulose pulp after different pretreatment methods, is examined at various temperatures (16-65°C) and up to 70% RH. The effect of drying temperature of MFC films on the water uptake is also investigated. The obtained solubility isotherms showed the typical downward curvature at moderate RH, while no upturn is observed at higher RH; the uptakes are in line with characteristic values for cellulose fibers. Enzymatically pretreated MFC dispersion showed lower solubility than carboxymethylated MFC, likely due to the different material structure, which results from the different preparation methods The experimental results are analyzed by Park and GAB models, which proved suitable to describe the observed behaviors. Interestingly, while no significant thermal effect is detected on water solubility above 35°C, the uptake at 16 and 25°C, at a given RH, is substantially lower than that at higher temperature, indicating that, in such range, sorption process is endothermic. Such unusual behavior for a cellulose-based system seems to be related mainly to the structural characteristics of MFC films, and to relaxation phenomena taking place upon water sorption. The diffusion kinetics, indeed, showed a clear Fickian behavior at low temperature and RH, whereas a secondary process seems to occur at high temperature and higher RH, leading to anomalous diffusion behaviors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of temperature and concentration on benzoyl peroxide bleaching efficacy and benzoic acid levels in whey protein concentrate.

PubMed

Smith, T J; Gerard, P D; Drake, M A

2015-11-01

Much of the fluid whey produced in the United States is a by-product of Cheddar cheese manufacture and must be bleached. Benzoyl peroxide (BP) is currently 1 of only 2 legal chemical bleaching agents for fluid whey in the United States, but benzoic acid is an unavoidable by-product of BP bleaching. Benzoyl peroxide is typically a powder, but new liquid BP dispersions are available. A greater understanding of the bleaching characteristics of BP is necessary. The objective of the study was to compare norbixin destruction, residual benzoic acid, and flavor differences between liquid whey and 80% whey protein concentrates (WPC80) bleached at different temperatures with 2 different benzoyl peroxides (soluble and insoluble). Two experiments were conducted in this study. For experiment 1, 3 factors (temperature, bleach type, bleach concentration) were evaluated for norbixin destruction using a response surface model-central composite design in liquid whey. For experiment 2, norbixin concentration, residual benzoic acid, and flavor differences were explored in WPC80 from whey bleached by the 2 commercially available BP (soluble and insoluble) at 5 mg/kg. In liquid whey, soluble BP bleached more norbixin than insoluble BP, especially at lower concentrations (5 and 10 mg/kg) at both cold (4°C) and hot (50°C) temperatures. The WPC80 from liquid whey bleached with BP at 50°C had lower norbixin concentration, benzoic acid levels, cardboard flavor, and aldehyde levels than WPC80 from liquid whey bleached with BP at 4°C. Regardless of temperature, soluble BP destroyed more norbixin at lower concentrations than insoluble BP. The WPC80 from soluble-BP-bleached wheys had lower cardboard flavor and lower aldehyde levels than WPC80 from insoluble-BP-bleached whey. This study suggests that new, soluble (liquid) BP can be used at lower concentrations than insoluble BP to achieve equivalent bleaching and that less residual benzoic acid remains in WPC80 powder from liquid whey bleached hot (50°C) than cold (4°C), which may provide opportunities to reduce benzoic acid residues in dried whey ingredients, expanding their marketability. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effects of intermolecular forces and backbone architecture on the phase behavior of fluorocopolymer-supercritical fluid mixtures

NASA Astrophysics Data System (ADS)

Mertdogan, Cynthia Asli

The impact of polymer backbone architecture on fluorocopolymer solubility in supercritical fluid (SCF) solvents is studied by systematically varying the chemical type of the repeat units in the main chain. The fluorocopolymers investigated include nonpolar copolymers of tetrafluoroethylene with 19 mol% hexafluoropropylene (FEPsb{19}) and 48 mol% hexafluoropropylene (FEPsb{48}) and a polar copolymer of vinylidene fluoride with 22 mol% hexafluoropropylene (Fluorelsp°ler ). The solvents are methodically varied from nonpolar perfluoroalkanes and SFsb6 to polar fluorocarbons and COsb2. Low molecular weight solvents are used to facilitate in interpreting the intermolecular forces that control fluorocopolymer solubility, although pressures in excess of 2,500 bar are sometimes needed to dissolve the fluorocopolymers in these simple solvents. Polarity effects, which vary inversely with temperature, are moderated by operating over a large temperature range from 0 to 300sp° C. A variable-volume view cell, capable of operating to high temperatures and high pressures, was designed and implemented to meet these extreme operating conditions. Increasing the polarizability of nonpolar solvents reduces the pressures required to dissolve FEPsb{19} by as much as 1,500 bar going from perfluoromethane to perfluoropropane. However, in polar solvents, the pressures required for FEPsb{19} solubility rise dramatically as the temperature is decreased due to the increase in polar, solvent-solvent interactions that do not favor the solubility of a nonpolar copolymer. Replacing semi-crystalline FEPsb{19} with amorphous FEPsb{48} yields the same trends in phase behavior. Therefore, crystallinity does not control the shape of these fluorocopolymer-SCF cloud-point curves. Adding a cosolvent to the solution can dramatically lower the pressures needed to dissolve the copolymer. Introducing the "cosolvent" directly into the polymer backbone by changing copolymer architecture is another method of modifying fluorocopolymer solubility as seen with the results for Fluorel-SCF mixtures compared to those for FEPsb{19}-SCF mixtures. A supercritical fractionation of FEPsb{19} provides information on the impact of molecular weight and end-group content on fluorocopolymer solubility. Challenges remain for modeling fluorocopolymer-solvent mixtures. The Sanchez-Lacombe equation cannot capture the characteristics of FEPsb{19}-SCF solvent phase behavior unless two empirical mixture parameters, one of which varies with temperature, are used.

A study of gas solubilities and transport properties in fuel cell electrolytes

NASA Technical Reports Server (NTRS)

Walker, R. D. J.

1972-01-01

An analysis of the rate of heat generation on the dissolution of sparingly soluble gas in electrolytes was made, and it leads to the conclusion that the temperature changes to be expected are much too small to be measured with precision owing to the slowness of the gas dissolution. It appears that more accurate gas solubility measurements are the only real hope of improved precision in heats of solution and other thermodynamic properties.

Correlation of Helium Solubility in Liquid Nitrogen

NASA Technical Reports Server (NTRS)

VanDresar, Neil T.; Zimmerli, Gregory A.

2012-01-01

A correlation has been developed for the equilibrium mole fraction of soluble gaseous helium in liquid nitrogen as a function of temperature and pressure. Experimental solubility data was compiled and provided by National Institute of Standards and Technology (NIST). Data from six sources was used to develop a correlation within the range of 0.5 to 9.9 MPa and 72.0 to 119.6 K. The relative standard deviation of the correlation is 6.9 percent.

Multimodel predictive system for carbon dioxide solubility in saline formation waters.

PubMed

Wang, Zan; Small, Mitchell J; Karamalidis, Athanasios K

2013-02-05

The prediction of carbon dioxide solubility in brine at conditions relevant to carbon sequestration (i.e., high temperature, pressure, and salt concentration (T-P-X)) is crucial when this technology is applied. Eleven mathematical models for predicting CO(2) solubility in brine are compared and considered for inclusion in a multimodel predictive system. Model goodness of fit is evaluated over the temperature range 304-433 K, pressure range 74-500 bar, and salt concentration range 0-7 m (NaCl equivalent), using 173 published CO(2) solubility measurements, particularly selected for those conditions. The performance of each model is assessed using various statistical methods, including the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). Different models emerge as best fits for different subranges of the input conditions. A classification tree is generated using machine learning methods to predict the best-performing model under different T-P-X subranges, allowing development of a multimodel predictive system (MMoPS) that selects and applies the model expected to yield the most accurate CO(2) solubility prediction. Statistical analysis of the MMoPS predictions, including a stratified 5-fold cross validation, shows that MMoPS outperforms each individual model and increases the overall accuracy of CO(2) solubility prediction across the range of T-P-X conditions likely to be encountered in carbon sequestration applications.

Microenvironmental pH-modification to improve dissolution behavior and oral absorption for drugs with pH-dependent solubility.

PubMed

Taniguchi, Chika; Kawabata, Yohei; Wada, Koichi; Yamada, Shizuo; Onoue, Satomi

2014-04-01

Drug release and oral absorption of drugs with pH-dependent solubility are influenced by the conditions in the gastrointestinal tract. In some cases, poor oral absorption has been observed for these drugs, causing insufficient drug efficacy. The pH-modification of a formulation could be a promising approach to overcome the poor oral absorption of drugs with pH-dependent solubility. The present review aims to summarize the pH-modifier approach and strategic analyses of microenvironmental pH for formulation design and development. We also provide literature- and patent-based examples of the application of pH-modification technology to solid dosage forms. For the pH-modification approach, the microenvironmental pH at the diffusion area can be altered by dissolving pH-modifying excipients in the formulation. The modulation of the microenvironmental pH could improve dissolution behavior of drugs with pH-dependent solubility, possibly leading to better oral absorption. According to this concept, the modulated level of microenvironmental pH and its duration can be key factors for improvement in drug dissolution. The measurement of microenvironmental pH and release of pH-modifier would provide theoretical insight for the selection of an appropriate pH-modifier and optimization of the formulation.

pH-dependent solubility and permeability profiles: A useful tool for prediction of oral bioavailability.

PubMed

Sieger, P; Cui, Y; Scheuerer, S

2017-07-15

pH-dependent solubility - permeability profiles offer a simple way to predict bioavailability after oral application, if bioavailability is only solubility and permeability driven. Combining both pH-dependent solubility and pH-dependent permeability in one diagram provides a pH-window (=ΔpH sol-perm ) from which the conditions for optimal oral bioavailability can be taken. The size of this window is directly proportional to the observed oral bioavailability. A set of 21 compounds, with known absolute human oral bioavailability, was used to establish this correlation. Compounds with ΔpH sol-perm <2 exhibit poor oral bioavailability (<25%). An increase of ΔpH sol-perm by one pH-unit increases oral bioavailability typically by approximately 25%. For compounds where ΔpH sol-perm ≥3 but still showing poor bioavailability, most probably other pharmacokinetic aspects (e.g. high clearance), are limiting exposure. Interestingly, the location of this pH-window seems to have a negligible influence on the observed oral bioavailability. In scenarios, where the bioavailability is impaired by certain factors, like for example proton pump inhibitor co-medication or food intake, the exact position of this pH-window might be beneficial for understanding the root cause. Copyright © 2017 Elsevier B.V. All rights reserved.

[Cold resistance of four evergreen broad-leaved tree species].

PubMed

Wang, Na; Wang, Kui Ling; Liu, Qing Hua; Liu, Qing Chao

2016-10-01

The leaves of four evergreen plants, i.e., Fatsia japonica, Nerium indicum, Mahonia bealei and Acer cinnamomifolium were used as the experimental materials. By measuring the changes of in vitro leaf in soluble sugar, soluble protein, free proline, POD activity, chlorophyll content and relative electrolytic conductivity under aritificial simulated low temperature, combining the measurements of SPAD, leaf surface features and anatomical changes in organizational structure in the process of natural wintering, the cold resistance of four evergreen tree species was evaluated comprehensively. The results showed that in the process of artificial low temperature stress, the chlorophyll content of the leaves of four evergreen species decreased, the content of soluble protein pea-ked at -20 ℃, and the soluble sugar, free proline, POD activity and relative electrolytic conductivity showed an overall upward trend. The semilethal temperatures of four species were -8.0, -13.4, -19.4 and -14.8 ℃, respectively. During the winter, the leaf SPAD of the four species changed markedly, reflecting that the change of relative chlorophyll content was related to the change of temperature. Meanwhile, the leaf thickness, cutin layer thickness, stockade tissue thickness and tightness of four species increased and the plasmolysis occurred thereafter. Also the content of starch grains and calcium oxalate cluster crystal increased. The typical stomatal pits and the intensive non-glandular trichome within the pits of N. indicum and the sclerenchyma of M. Bealei could improve the cold resistance of plants to some extent. In addition, the phenomena like the breakage of wax layer in leaf surface, the fracture of epidermal hair and the deformation of palisade tissue indicated that plants were damaged to a certain extent by low temperature.

Determination of hydrogen permeability in uncoated and coated superalloys

NASA Technical Reports Server (NTRS)

Bhattacharyya, S.; Vesely, E. J., Jr.; Hill, V. L.

1981-01-01

Hydrogen permeability, diffusivity, and solubility data were obtained for eight wrought and cast high temperature alloys over the range 650 to 815 C. Data were obtained for both uncoated alloys and wrought alloys coated with four commercially available coatings. Activation energies for permeability, diffusivity and solubility were calculated.

SOLUBILITY OF ORGANIC BIOCIDES IN SUPERCRITICAL CO2 AND CO2+ COSOLVENT MIXTURES

EPA Science Inventory

Solubilities of four organic biocides in supercritical carbon dioxide (Sc-CO2) were measured using a dynamic flowr apparatus over a pressure range of 10 to 30 MPa and temperature of 35-80 degrees C. The biocides studied were: Amical-48 (diiodomethyl p-tolyl sulfone), chlorothalo...

Oil shale extraction using super-critical extraction

NASA Technical Reports Server (NTRS)

Compton, L. E. (Inventor)

1983-01-01

Significant improvement in oil shale extraction under supercritical conditions is provided by extracting the shale at a temperature below 400 C, such as from about 250 C to about 350 C, with a solvent having a Hildebrand solubility parameter within 1 to 2 Hb of the solubility parameter for oil shale bitumen.

Rapid, Efficient Determination of Recrystallization Solvents at the Microscale Level.

ERIC Educational Resources Information Center

Craig, Rhoda E. R.

1989-01-01

Presents a procedure used in sophomore level organic chemistry which has been particularly useful for organic qualitative analysis. Uses a nine-well spotplate and one-two mg of solid and three-four drops of eight different solvents. Solubility is checked at different temperatures. Provides a solubility table. (MVL)

Sweet Polymers: Poly(2-ethyl-2-oxazoline) Glycopolymers by Reductive Amination.

PubMed

Mees, Maarten A; Effenberg, Christiane; Appelhans, Dietmar; Hoogenboom, Richard

2016-12-12

Carbohydrates are important in signaling, energy storage, and metabolism. Depending on their function, carbohydrates can be part of larger structures, such as glycoproteins, glycolipids, or other functionalities (glycoside). To this end, polymers can act as carriers of carbohydrates in so-called glycopolymers, which mimic the multivalent carbohydrate functionalities. We chose a biocompatible poly(2-ethyl-2-oxazoline) (PEtOx) as the basis for making glycopolymers. Via the partial hydrolysis of PEtOx, a copolymer of PEtOx and polyethylenimine (PEI) was obtained; the subsequent reductive amination with the linear forms of glucose and maltose yielded the glycopolymers. The ratios of PEtOx and carbohydrates were varied systematically, and the solution behaviors of the resulting glycoconjugates are discussed. Dynamic light scattering (DLS) revealed that, depending on the carbohydrate ratio, the glycopolymers were either fully water-soluble or formed agglomerates in a temperature-dependent manner. Finally, these polymers were tested for their biological availability by studying their lectin binding ability with Concanavalin A.

Solubility of carbohydrates in heavy water.

PubMed

Cardoso, Marcus V C; Carvalho, Larissa V C; Sabadini, Edvaldo

2012-05-15

The solubility of several mono-(glucose and xylose), di-(sucrose and maltose), tri-(raffinose) and cyclic (α-cyclodextrin) saccharides in H(2)O and in D(2)O were measured over a range of temperatures. The solution enthalpies for the different carbohydrates in the two solvents were determined using the vant' Hoff equation and the values in D(2)O are presented here for the first time. Our findings indicate that the replacement of H(2)O by D(2)O remarkably decreases the solubilities of the less soluble carbohydrates, such as maltose, raffinose and α-cyclodextrin. On the other hand, the more soluble saccharides, glucose, xylose, and sucrose, are practically insensitive to the H/D replacement in water. Copyright © 2012 Elsevier Ltd. All rights reserved.

The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

NASA Astrophysics Data System (ADS)

Deditius, Artur P.; Reich, Martin; Kesler, Stephen E.; Utsunomiya, Satoshi; Chryssoulis, Stephen L.; Walshe, John; Ewing, Rodney C.

2014-09-01

The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au, porphyry Cu, Cu-Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS), Witwatersrand Au, iron oxide copper gold (IOCG), and coal deposits. Pyrite included in the data compilation formed under temperatures from ∼30 to ∼600 °C and in a wide variety of geological environments. The pyrite Au-As data form a wedge-shaped zone in compositional space, and the fact that most data points plot below the solid solubility limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native Au. The analytical data also show that the solid solubility limit of Au in arsenian pyrite defined by an Au/As ratio of 0.02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal-chemical properties of pyrite and post-depositional alteration. Compilation of Au-As concentrations and formation temperatures for pyrite indicates that Au and As solubility in pyrite is retrograde; Au and As contents decrease as a function of increasing temperature from ∼200 to ∼500 °C. Based on these results, two major Au-As trends for Au-bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-type and orogenic Au deposits where compositions are largely controlled by fluid-rock interactions and/or can be highly perturbed by changes in temperature and alteration by hydrothermal fluids. The second trend consists of pyrites from porphyry Cu and epithermal Au deposits, which are characterised by compositions that preserve the Au/As signature of mineralizing magmatic-hydrothermal fluids, confirming the role of this sulfide in controlling metal ratios in ore systems.

Solid dispersions of Myricetin with enhanced solubility: Formulation, characterization and crystal structure of stability-impeding Myricetin monohydrate crystals

NASA Astrophysics Data System (ADS)

Mureşan-Pop, M.; Pop, M. M.; Borodi, G.; Todea, M.; Nagy-Simon, T.; Simon, S.

2017-08-01

Three solid dispersion forms of Myricetin combined with the Polyvinylpyrrolidone were successfully prepared by spray drying method, and characterized by X-ray powder diffraction, thermal analysis, infrared spectroscopy and optical microscopy. Zeta potential measurements provided indications on solid dispersions stability in aqueous suspension related to their storage at elevated temperature and relative humidity, which depends on the Myricetin load. By increase of Myricetin load, the stability of the solid dispersion is impeded due to growth of Myricetin monohydrate crystals. The amorphous dispersions with 10% and 50% Myricetin load are stable and, compared to pure Myricetin, their aqueous solubility is enhanced by a factor of 47 and 13, respectively. The dispersion with 80% Myricetin load is unstable on storage, and this behavior acts in conjunction with the development of Myricetin monohydrate crystals. Single-crystal X-ray diffraction results obtained for Myricetin monohydrate reveal a structure of an infinite 2D network of hydrogen-bonded molecules involving all six hydroxyl groups of Myricetin. The water molecules are positioned in between the infinite chains, and contribute via H-bonds to robust crystal packing. The calculated needle-like morphology of monohydrate form is in agreement with the optical microscopy results. The study shows that the solid amorphous dispersions with up to 50% Myricetin load are a viable option for achieving substantial solubility improvement of Myricetin, and supports their potential use in pharmaceutical applications.

Experiments on the Multiphase Chemistry of Isocyanic Acid, HNCO.

NASA Astrophysics Data System (ADS)

Roberts, J. M.; Liu, Y.

2015-12-01

Isocyanic acid, HNCO, has emerged as a potentially important reduced nitrogen compound that is emitted in wildfires, and may have health effect implications. The extent of the health effects depends on the solubility of HNCO in aqueous and non-aqueous solutions and the relative rates of hydrolysis versus carbamylation reactions (for example: HNCO + ROH => H2NC(O)OR). We report here results of studies of HNCO solubility and its reaction in buffered aqueous solutions (pH3), tridecane, and n-octanol at temperatures over the range 5 to 37°C. From these data, the heats of solution and activation energy of hydrolysis are estimated, and a partition coefficient between n-octanol and water at 25°C is greater than 1 for low pH solutions, indicating appreciable portioning to a non-polar phase, but HNCO will be distributed mostly in the aqueous phase at neutral pH. In addition, it was found that the rate of reaction of HNCO with n-octanol was competitive with hydrolysis under physiologically relevant conditions (pH7.4, 37°C), indicating that carbamylation of ROH groups could be significant. Based on these results, research on the carbamylation of other functional groups, and solubility and reaction studies of other isocyanates (e.g. CH3NCO) are warranted. The implications of this multi-phase chemistry for global exposures to wildfire emissions will be discussed.

On the refractive index of sodium iodide solutions for index matching in PIV

NASA Astrophysics Data System (ADS)

Bai, Kunlun; Katz, Joseph

2014-04-01

Refractive index matching has become a popular technique for facilitating applications of modern optical diagnostic techniques, such as particle image velocimetry, in complex systems. By matching the refractive index of solid boundaries with that of the liquid, unobstructed optical paths can be achieved for illumination and image acquisition. In this research note, we extend previously provided data for the refractive index of aqueous solutions of sodium iodide (NaI) for concentrations reaching the temperature-dependent solubility limit. Results are fitted onto a quadratic empirical expression relating the concentration to the refractive index. Temperature effects are also measured. The present range of indices, 1.333-1.51, covers that of typical transparent solids, from silicone elastomers to several recently introduced materials that could be manufactured using rapid prototyping. We also review briefly previous measurements of the refractive index, viscosity, and density of NaI solutions, as well as prior research that has utilized this fluid.

Rutile solubility in NaF–NaCl–KCl-bearing aqueous fluids at 0.5–2.79GPa and 250–650°C

DOE PAGES

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; ...

2016-01-14

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Rutile solubility in NaF-NaCl-KCl-bearing aqueous fluids at 0.5-2.79 GPa and 250-650 °C

NASA Astrophysics Data System (ADS)

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; Chow, Paul; Xiao, Yuming; Hanchar, John M.; Tschauner, Oliver; Shen, Guoyin

2016-03-01

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nb and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 °C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at ∼300 °C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 °C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log DZr ∼10-25 m2/s at 650 °C and ∼10-30 m2/s at 250 °C) with diffusion length-scales of <0.2 μm in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility.

Thermal inactivation of infectious pancreatic necrosis virus in a peptone-salt medium mimicking the water-soluble phase of hydrolyzed fish by-products.

PubMed

Nygaard, Halvor; Modahl, Ingebjørg; Myrmel, Mette

2012-04-01

Infectious pancreatic necrosis virus (IPNV) (serotype Sp) was exposed to temperatures between 60 and 90°C in a medium mimicking the water-soluble phase of hydrolyzed fish by-products. D values ranged from 290 to 0.5 min, and the z value was approximately 9.8°C. Addition of formic acid to create a pH 4 medium did not enhance heat inactivation. Predicted inactivation effects at different temperature-time combinations are provided.

Solubility of single gases carbon dioxide and hydrogen sulfide in aqueous solutions of N-methyldiethanolamine in the temperature range 313--413 K at pressures up to 5 MPa

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

Kuranov, G.; Smirnova, N.A.; Rumpf, B.

1996-06-01

Experimental results for the solubility of the single gases carbon dioxide and hydrogen sulfide in aqueous solutions of 2,2{prime}-methyliminodiethanol (N-methyldiethanolamine (MDEA)) at temperatures between 313 and 413 K and total pressures up to 5 MPa are reported. A model taking into account chemical reactions as well as physical interactions is used to correlate the new data. The correlation is also used to compare the new experimental data with literature data.

Passivation of high temperature superconductors

NASA Technical Reports Server (NTRS)

Vasquez, Richard P. (Inventor)

1991-01-01

The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material.

Investigation of air solubility in jet A fuel at high pressures

NASA Technical Reports Server (NTRS)

Rupprecht, S. D.; Faeth, G. M.

1981-01-01

The solubility and density properties of saturated mixtures of fuels and gases were measured. The fuels consisted of Jet A and dodecane, the gases were air and nitrogen. The test range included pressures of 1.03 to 10.34 MPa and temperatures of 298 to 373 K. The results were correlated successfully, using the Soave equation of state. Over this test range, dissolved gas concentrations were roughly proportional to pressure and increased slightly with increasing temperature. Mixture density was relatively independent of dissolved gas concentration.

Formation of hydrothermal tin deposits: Raman spectroscopic evidence for an important role of aqueous Sn(IV) species

NASA Astrophysics Data System (ADS)

Schmidt, Christian

2018-01-01

The speciation of tin and the solubility of cassiterite in H2O + HCl were determined at temperatures to 600 °C using in situ Raman spectroscopy. In addition, information on the fluid-melt partition of Sn was obtained at 700 °C and indicated a preference of the fluid only at HCl concentrations that are much higher than in fluids exsolved from natural felsic melts. Dissolution of cassiterite generally resulted in formation of Sn(IV) species unless reduced conditions were generated by hydrogen permeation or carbohydrates in the starting material. The prevalent aqueous Sn(IV) species was [SnCl4(H2O)2]0, with additional [SnCl3(H2O)3]+ and [SnCl5(H2O)]-. The only detectable Sn(II) species was very likely [Sn(II)Cl3]-. Cassiterite solubility increased with HCl concentration and was generally high in H2O+HCl fluids, with no strong dependencies on temperature, pressure, or the oxidation state of tin in the fluid. The Sn(IV) concentrations at 500 and 600 °C determined from the integrated ν1[Sn(IV)sbnd Cl] band intensity are in good agreement with literature data on the cassiterite solubility in H2O + HCl at oxygen fugacities along the hematite-magnetite buffer. The combined results from previous experimental studies and this study demonstrate that HCl molality is a crucial parameter for hydrothermal mobilization and transport of tin and for cassiterite precipitation, and that pH, pressure and temperature are less important. Current models on hydrothermal tin deposit formation need to be augmented to include Sn(IV)sbnd Cl complexes as significant tin-transporting species. Irrespective of the oxidation state of tin in the fluid, cassiterite precipitates due to reaction of the hydrothermal fluid with the wall rock (greisen or skarn formation), dilution (mixing with meteoric water) or a decrease in the HCl activity in the aqueous liquid by boiling. A redox reaction is only required for tin transported as Sn(II) to be converted to Sn(IV).

Complementarity determining regions and frameworks contribute to the disulfide bond independent folding of intrinsically stable scFv

PubMed Central

Gąciarz, Anna

2017-01-01

CyDisCo is a system facilitating disulfide bond formation in recombinant proteins in the cytoplasm of Escherichia coli. Previously we screened for soluble expression of single chain antibody fragments (scFv) in the cytoplasm of E. coli in the presence and absence of CyDisCo, with >90% being solubly expressed. Two scFv, those derived from natalizumab and trastuzumab, were solubly produced in high amounts even in the absence of folding catalysts i.e. disulfide bond formation is not critical for their folding. Here we investigate the contribution of the framework and the complementarity determining regions (CDRs) of scFv to the disulfide-independence of folding. We swapped CDRs between four scFv that have different properties, including two scFv that can efficiently fold independently from disulfide bonds and two more disulfide-dependent scFv. To confirm disulfide-independence we generated cysteine to alanine mutants of the disulfide-independent scFv. All of the scFv were tested for soluble expression in the cytoplasm of E. coli in the presence and absence of the oxidative folding catalysts Erv1p and PDI. Eight of the hybrid scFv were solubly produced in the presence of CyDisCo, while seven were solubly produced in the absence of CyDisCo, though the yields were often much lower when CyDisCo was absent. Soluble expression was also observed for scFv natalizumab and trastuzumab containing no cysteines. We compared yields, thermal stability and secondary structure of solubly produced scFv and undertook binding studies by western blotting, dot blotting or surface plasmon resonance of those produced in good yields. Our results indicate that both the CDRs and the framework contribute to the disulfide-dependence of soluble production of scFv, with the CDRs having the largest effect. In addition, there was no correlation between thermal stability and disulfide-dependence of folding and only a weak correlation between the yield of protein and the thermal stability of the protein. PMID:29253024

Complementarity determining regions and frameworks contribute to the disulfide bond independent folding of intrinsically stable scFv.

PubMed

Gąciarz, Anna; Ruddock, Lloyd W

2017-01-01

CyDisCo is a system facilitating disulfide bond formation in recombinant proteins in the cytoplasm of Escherichia coli. Previously we screened for soluble expression of single chain antibody fragments (scFv) in the cytoplasm of E. coli in the presence and absence of CyDisCo, with >90% being solubly expressed. Two scFv, those derived from natalizumab and trastuzumab, were solubly produced in high amounts even in the absence of folding catalysts i.e. disulfide bond formation is not critical for their folding. Here we investigate the contribution of the framework and the complementarity determining regions (CDRs) of scFv to the disulfide-independence of folding. We swapped CDRs between four scFv that have different properties, including two scFv that can efficiently fold independently from disulfide bonds and two more disulfide-dependent scFv. To confirm disulfide-independence we generated cysteine to alanine mutants of the disulfide-independent scFv. All of the scFv were tested for soluble expression in the cytoplasm of E. coli in the presence and absence of the oxidative folding catalysts Erv1p and PDI. Eight of the hybrid scFv were solubly produced in the presence of CyDisCo, while seven were solubly produced in the absence of CyDisCo, though the yields were often much lower when CyDisCo was absent. Soluble expression was also observed for scFv natalizumab and trastuzumab containing no cysteines. We compared yields, thermal stability and secondary structure of solubly produced scFv and undertook binding studies by western blotting, dot blotting or surface plasmon resonance of those produced in good yields. Our results indicate that both the CDRs and the framework contribute to the disulfide-dependence of soluble production of scFv, with the CDRs having the largest effect. In addition, there was no correlation between thermal stability and disulfide-dependence of folding and only a weak correlation between the yield of protein and the thermal stability of the protein.

Solubility of K in Fe-S liquid, silicate-K/Fe-S/liq equilibria, and their planetary implications

NASA Technical Reports Server (NTRS)

Gangully, J.; Kennedy, G. C.

1977-01-01

Potassium has been found to have extremely limited absolute solubility in Fe-S liquid in the pressure-temperature range of 18 to 40 kbars, 1050 to 1150 C, and fO2 within the field of metallic iron. It also partitioned into a certain silicate phase highly in preference to Fe-S liquid at 30 kbar and 1100 C. The dependence of the partitioning of K between solid silicate and Fe-S liquid on fO2 and compositions of mineral solid solutions have been analyzed. These experimental data, along with those of others, limit the amount of K that could fractionate in Fe-S liquid layers or a core in the early history of the moon and, thus, act as localized heat sources in its thermal history models; the data also seem to argue against a chondritic abundance of potassium for earth. The question of fractionation of enough K-40 in an Fe-S liquid outer core of earth to provide the necesary thermal energy for the geomagnetic dynamo remains unresolved.

Application of a constant hole volume Sanchez-Lacombe equation of state to mixtures relevant to polymeric foaming.

PubMed

von Konigslow, Kier; Park, Chul B; Thompson, Russell B

2018-06-06

A variant of the Sanchez-Lacombe equation of state is applied to several polymers, blowing agents, and saturated mixtures of interest to the polymer foaming industry. These are low-density polyethylene-carbon dioxide and polylactide-carbon dioxide saturated mixtures as well as polystyrene-carbon dioxide-dimethyl ether and polystyrene-carbon dioxide-nitrogen ternary saturated mixtures. Good agreement is achieved between theoretically predicted and experimentally determined solubilities, both for binary and ternary mixtures. Acceptable agreement with swelling ratios is found with no free parameters. Up-to-date pure component Sanchez-Lacombe characteristic parameters are provided for carbon dioxide, dimethyl ether, low-density polyethylene, nitrogen, polylactide, linear and branched polypropylene, and polystyrene. Pure fluid low-density polyethylene and nitrogen parameters exhibit more moderate success while still providing acceptable quantitative estimations. Mixture estimations are found to have more moderate success where pure components are not as well represented. The Sanchez-Lacombe equation of state is found to correctly predict the anomalous reversal of solubility temperature dependence for low critical point fluids through the observation of this behaviour in polystyrene nitrogen mixtures.

Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

NASA Astrophysics Data System (ADS)

Lade, Steven J.; Donges, Jonathan F.; Fetzer, Ingo; Anderies, John M.; Beer, Christian; Cornell, Sarah E.; Gasser, Thomas; Norberg, Jon; Richardson, Katherine; Rockström, Johan; Steffen, Will

2018-05-01

Changes to climate-carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate-carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate-carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate-carbon feedback; and concentration-carbon feedbacks may be more sensitive to future climate change than climate-carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.

Microwave pyrolysis of distillers dried grain with solubles (DDGS) for biofuel production.

PubMed

Lei, Hanwu; Ren, Shoujie; Wang, Lu; Bu, Quan; Julson, James; Holladay, John; Ruan, Roger

2011-05-01

Microwave pyrolysis of distillers dried grain with solubles (DDGS) was investigated to determine the effects of pyrolytic conditions on the yields of bio-oil, syngas, and biochar. Pyrolysis process variables included reaction temperature, time, and power input. Microwave pyrolysis of DDGS was analyzed using response surface methodology to find out the effect of process variables on the biofuel (bio-oil and syngas) conversion yield and establish prediction models. Bio-oil recovery was in the range of 26.5-50.3 wt.% of the biomass. Biochar yields were 23.5-62.2% depending on the pyrolysis conditions. The energy content of DDGS bio-oils was 28 MJ/kg obtained at the 650°C and 8 min, which was about 66.7% of the heating value of gasoline. GC/MS analysis indicated that the biooil contained a series of important and useful chemical compounds: aliphatic and aromatic hydrocarbons. At least 13% of DDGS bio-oil was the same hydrocarbon compounds found in regular unleaded gasoline. Copyright © 2011 Elsevier Ltd. All rights reserved.

Microwave pyrolysis of distillers dried grain with solubles (DDGS) for biofuel production

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

Lei, Hanwu; Ren, Shoujie; Wang, Lu

2011-05-01

Microwave pyrolysis of distillers dried grain with solubles (DDGS) was investigated to determine the effects of pyrolytic conditions on the yields of bio-oil, syngas, and biochar. Pyrolysis process variables included reaction temperature, time, and power input. Microwave pyrolysis of DDGS was analyzed using response surface methodology to find out the effect of process variables on the biofuel (bio-oil and syn- gas) conversion yield and establish prediction models. Bio-oil recovery was in the range of 26.5–50.3 wt.% of the biomass. Biochar yields were 23.5–62.2% depending on the pyrolysis conditions. The energy con- tent of DDGS bio-oils was 28 MJ/kg obtained atmore » the 650 oC and 8 min, which was about 66.7% of the heat- ing value of gasoline. GC/MS analysis indicated that the biooil contained a series of important and useful chemical compounds: aliphatic and aromatic hydrocarbons. At least 13% of DDGS bio-oil was the same hydrocarbon compounds found in regular unleaded gasoline.« less

The neurite growth inhibitory effects of soluble TNFα on developing sympathetic neurons are dependent on developmental age.

PubMed

Nolan, Aoife M; Collins, Louise M; Wyatt, Sean L; Gutierrez, Humberto; O'Keeffe, Gerard W

2014-01-01

During development, the growth of neural processes is regulated by an array of cellular and molecular mechanisms which influence growth rate, direction and branching. Recently, many members of the TNF superfamily have been shown to be key regulators of neurite growth during development. The founder member of this family, TNFα can both promote and inhibit neurite growth depending on the cellular context. Specifically, transmembrane TNFα promotes neurite growth, while soluble TNFα inhibits it. While the growth promoting effects of TNFα are restricted to a defined developmental window of early postnatal development, whether the growth inhibitory effects of soluble TNFα occur throughout development is unknown. In this study we used the extensively studied, well characterised neurons of the superior cervical ganglion to show that the growth inhibitory effects of soluble TNFα are restricted to a specific period of late embryonic and early postnatal development. Furthermore, we show that this growth inhibitory effect of soluble TNFα requires NF-κB signalling at all developmental stages at which soluble TNFα inhibits neurite growth. These findings raise the possibility that increases in the amount of soluble TNFα in vivo, for example as a result of maternal inflammation, could negatively affect neurite growth in developing neurons at specific stages of development. Copyright © 2015 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

Hydrotropic Solubilization of Lipophilic Drugs for Oral Delivery: The Effects of Urea and Nicotinamide on Carbamazepine Solubility–Permeability Interplay

PubMed Central

Beig, Avital; Lindley, David; Miller, Jonathan M.; Agbaria, Riad; Dahan, Arik

2016-01-01

Hydrotropy refers to increasing the water solubility of otherwise poorly soluble compound by the presence of small organic molecules. While it can certainly increase the apparent solubility of a lipophilic drug, the effect of hydrotropy on the drugs’ permeation through the intestinal membrane has not been studied. The purpose of this work was to investigate the solubility–permeability interplay when using hydrotropic drug solubilization. The concentration-dependent effects of the commonly used hydrotropes urea and nicotinamide, on the solubility and the permeability of the lipophilic antiepileptic drug carbamazepine were studied. Then, the solubility–permeability interplay was mathematically modeled, and was compared to the experimental data. Both hydrotropes allowed significant concentration-dependent carbamazepine solubility increase (up to ∼30-fold). A concomitant permeability decrease was evident both in vitro and in vivo (∼17-fold for nicotinamide and ∼9-fold for urea), revealing a solubility–permeability tradeoff when using hydrotropic drug solubilization. A relatively simplified simulation approach based on proportional opposite correlation between the solubility increase and the permeability decrease at a given hydrotrope concentration allowed excellent prediction of the overall solubility–permeability tradeoff. In conclusion, when using hydrotropic drug solubilization it is prudent to not focus solely on solubility, but to account for the permeability as well; achieving optimal solubility–permeability balance may promote the overall goal of the formulation to maximize oral drug exposure. PMID:27826241

High throughput screening: an in silico solubility parameter approach for lipids and solvents in SLN preparations.

PubMed

Shah, Malay; Agrawal, Yadvendra

2013-01-01

The present paper describes an in silico solubility behavior of drug and lipids, an essential screening study in preparation of solid lipid nanoparticles (SLN). Ciprofloxacin HCl was selected as a model drug along with 11 lipids and 5 organic solvents. In silico miscibility study of drug/lipid/solvent was performed using Hansen solubility parameter approach calculated by group contribution method of Van Krevelen and Hoftyzer. Predicted solubility was validated by determining solubility of lipids in various solvent at different temperature range, while miscibility of drug in lipids was determined by apparent solubility study and partition experiment. The presence of oxygen and OH functionality increases the polarity and hydrogen bonding possibilities of the compound which has reflected the highest solubility parameter values for Geleol and Capmul MCM C8. Ethyl acetate, Geleol and Capmul MCM C8 was identified as suitable organic solvent, solid lipid and liquid lipid respectively based on a solubility parameter approach which was in agreement with the result of an apparent solubility study and partition coefficient. These works demonstrate the validity of solubility parameter approach and provide a feasible predictor to the rational selection of excipients in designing SLN formulation.

Solubility of 3-Caffeoylquinic Acid in Different Solvents at 291-340 K

NASA Astrophysics Data System (ADS)

Wang, Y. T.; Zhang, C. L.; Cheng, X. L.; Zhao, J. H.; Wang, L. C.

2017-12-01

Using a laser monitoring observation technique the solubilities of 3-caffeoylquinic acid in pure solvents, water, methanol, ethanol, 1-propanol, 1-butanol, and two mixed solvents, methanol + water, ethanol + water have been determined at temperature range from 291-340 K. The experimental data were correlated by the modified Apelblat equation, λ h equation, and ideal model. The calculated solubilities were turned out very consistent with the experimental results, and the modified Apelblat equation shows the best agreement.

Hydrogen dissolution in palladium: A resistometric study under pressure

NASA Astrophysics Data System (ADS)

Magnouche, A.; Fromageau, R.

1984-09-01

The hydrogen solubility in palladium in equilibrium with H2 gas has been measured, between room temperature and 540 °C, using a resistometric method, for pressures ranging between 0.01 and 10 MPa. In these conditions, the experimentally determined values of the solubility and of the dissolution enthalpy exhibit very close agreement with those obtained by other methods (calorimetry, volumetry, etc.), or after electrolytic charging. This good agreement demonstrates the validity of the resistometric method for determination of the solubility of hydrogen in metals.

The solubility of hydrogen in rhodium, ruthenium, iridium and nickel.

NASA Technical Reports Server (NTRS)

Mclellan, R. B.; Oates, W. A.

1973-01-01

The temperature variation of the solubility of hydrogen in rhodium, ruthenium, iridium, and nickel in equilibrium with H2 gas at 1 atm pressure has been measured by a technique involving saturating the solvent metal with hydrogen, quenching, and analyzing in resultant solid solutions. The solubilities determined are small (atom fraction of H is in the range from 0.0005 to 0.00001, and the results are consistent with the simple quasi-regular model for dilute interstitial solid solutions. The relative partial enthalpy and excess entropy of the dissolved hydrogen atoms have been calculated from the solubility data and compared with well-known correlations between these quantities.

Dynamics of Phase Transitions in a Snow Mass Containing Water-Soluble Salt Particles

NASA Astrophysics Data System (ADS)

Zelenko, V. L.; Heifets, L. I.; Orlov, Yu. N.; Voskresenskiy, N. M.

2018-07-01

A macrokinetic approach is used to describe the dynamics of phase transitions in a snow mass containing water-soluble salt particles. Equations are derived that describe the rate of salt granule dissolution and the change in the phase composition and temperature of a snow mass under the conditions of heat transfer with an isothermal surface. An experimental setup that models the change in the state of a snow mass placed on an isothermal surface is created to verify theoretical conclusions. Experimental observations of the change in temperature of the snow mass are compared to theoretical calculations. The mathematical model that is developed can be used to predict the state of a snow mass on roads treated with a deicing agent, or to analyze the state of snow masses containing water-soluble salt inclusions and resting on mountain slopes.

Determination of process parameters for curcumin - dextrose cocrystallization

NASA Astrophysics Data System (ADS)

Katherine; Nugroho, Denny; Sugih, Asaf K.

2018-01-01

Curcumin is a polyphenol that could act as anti-oxidant and anti - inflammation agent. It is usually isolated from rhizome plants such as turmeric and temulawak. Despite its many favorable properties, curcumin is practically insoluble in water, thus limiting its application. In the present investigation, variables affecting preparation of curcumin-dextrose cocrystal were examined with the aim to increase the solubility of curcumin. The effect of different processing conditions, such as water to dextrose ratio, final heating temperature and water bath temperature to the formation of cocrystal, were studied and the yield and solubility of curcumin - dextrose cocrystal products were analyzed. The morphology of the cocrystals were also analyzed using SEM and fluorescence microscopy.. Curcumin - dextrose cocrystals showed a significant increase in solubility up to 25 mg curcumin per mL water compared to pure curcumin.

Enhanced thermophilic fermentative hydrogen production from cassava stillage by chemical pretreatments.

PubMed

Wang, Wen; Luo, Gang; Xie, Li; Zhou, Qi

2013-01-01

Acid and alkaline pretreatments for enhanced hydrogen production from cassava stillage were investigated in the present study. The result showed that acid pretreatment was suitable for enhancement of soluble carbohydrate while alkaline pretreatment stimulated more soluble total organic carbon production from cassava stillage. Acid pretreatment thereby has higher capacity to promote hydrogen production compared with alkaline pretreatment. Effects of pretreatment temperature, time and acid concentration on hydrogen production were also revealed by response surface methodology. The results showed that the increase of all factors increased the soluble carbohydrate production, whereas hydrogen production was inhibited when the factors exceeded their optimal values. The optimal conditions for hydrogen production were pretreatment temperature 89.5 °C, concentration 1.4% and time 69 min for the highest hydrogen production of 434 mL, 67% higher than raw cassava stillage.

Trichomonas vaginalis: identification of soluble and membrane-associated phospholipase A1 and A2 activities with direct and indirect hemolytic effects.

PubMed

Vargas-Villarreal, Javier; Mata-Cárdenas, Benito David; Palacios-Corona, Rebeca; González-Salazar, Francisco; Cortes-Gutierrez, Elva I; Martínez-Rodríguez, Herminia G; Said-Fernández, Salvador

2005-02-01

A direct hemolytic activity, dependent on phospholipase A (PLA) activity, was located in the particulate subcellular fraction (P30) of Trichomonas vaginalis. We identified soluble direct and indirect hemolytic activities in the spent medium and soluble fraction (S30) of T. vaginalis strain GT-13. Spent medium showed the highest specific indirect hemolytic activity (SIHA) at pH 6.0 (91 indirect hemolytic units [HU]/mg/hr). Spent medium and P30, but not S30, showed direct hemolytic activity. PLA activity was protein dose dependent and time dependent. The highest PLA activity was observed at pH 6.0. All trichomonad preparations showed phospholipase A1 (PLA A1) and phospholipase A2 (PLA A2) activities. Indirect and direct hemolytic activity and PLA A1 and PLA A2 diminished at pH 6.0 and 8.0 with increasing concentrations of Rosenthal's inhibitor. The greatest effect was observed with 80 microM at pH 6.0 on the SIHA of S30 (83% reduction) and the lowest at pH 8.0, also on the SIHA of S30 (26% reduction). In conclusion, T. vaginalis contains particulate and soluble acidic, and alkaline direct and indirect hemolytic activities, which are partially dependent on alkaline or acidic PLA A1 and PLA A2 enzymes. These could be responsible for the contact-dependent and -independent hemolytic and cytolytic activities of T. vaginalis.

A Comparison of Photosynthetic Characteristics of Encelia Species Possessing Glabrous and Pubescent Leaves 1

PubMed Central

Ehleringer, James R.; Björkman, Olle

1978-01-01

Measurements of the dependence of photosynthesis on light, CO2, and temperature are reported for two species of Encelia (Compositae) which differ in leaf pubescence and in geographical distribution. Encelia californica is glabrous and occurs in relatively mild, but arid habitats and Encelia farinosa is heavily pubescent and occurs in hot, arid habitats. Both species possess the C3 photosynthetic pathway. Under high irradiances and normal atmospheric conditions the two species have high photosynthetic rates, exceeding 3 nanomoles of CO2 per square centimeter per second (48 milligrams of CO2 per square decimeter per hour) and complete light saturation does not occur by full noon sunlight. The high photosynthetic capacity is related to a high efficiency of utilization of intercellular CO2 combined with high stomatal conductance. Leaf estimates of total soluble protein and fraction I protein are higher in these species than in most plants, although the proportion of fraction I protein is not higher. Both E. californica and E. farinosa attain a maximum rate of photosynthesis between 25 and 30 C, despite the fact that the two species grow in very different thermal habitats. Neither E. californica nor E. farinosa shows significant acclimation in the temperature dependence of photosynthesis when grown under different temperature regimes. The presence of leaf hairs which reduce leaf absorptance and consequently leaf temperature plays an important part in the ability of E. farinosa to survive in its native high temperature environment. When the effects of pubescence are taken into account, there are few if any significant differences in the photosynthetic characteristics of the two species. PMID:16660483

Pyrolysis temperature affects phosphorus transformation in biochar: Chemical fractionation and (31)P NMR analysis.

PubMed

Xu, Gang; Zhang, You; Shao, Hongbo; Sun, Junna

2016-11-01

Phosphorus (P) recycling or reuse by pyrolyzing crop residue has recently elicited increased research interest. However, the effects of feedstock and pyrolysis conditions on P species have not been fully understood. Such knowledge is important in identifying the agronomic and environmental uses of biochar. Residues of three main Chinese agricultural crops and the biochars (produced at 300°C-600°C) derived from these crops were used to determine P transformations during pyrolysis. Hedley sequential fractionation and (31)P NMR analyses were used in the investigation. Our results showed that P transformation in biochar was significantly affected by pyrolysis temperature regardless of feedstock (Wheat straw, maize straw and peanut husk). Pyrolysis treatment transformed water soluble P into a labile (NaHCO3-Pi) or semi-labile pool (NaOH-Pi) and into a stable pool (Dil. HCl P and residual-P). At the same time, organic P was transformed into inorganic P fractions which was identified by the rapid decomposition of organic P detected with solution (31)P NMR. The P transformation during pyrolysis process suggested more stable P was formed at a higher pyrolysis temperature. This result was also evidenced by the presence of less soluble or stable P species, such as such as poly-P, crandallite (CaAl3(OH)5(PO4)2) and Wavellite (Al3(OH)3(PO4)2·5H2O), as detected by solid-state (31)P NMR in biochars formed at a higher pyrolysis temperature. Furthermore, a significant proportion of less soluble pyrophosphate was identified by solution (2%-35%) and solid-state (8%-53%) (31)P NMR, which was also responsible for the stable P forms at higher pyrolysis temperature although their solubility or stability requires further investigation. Results suggested that a relatively lower pyrolysis temperature retains P availability regardless of feedstock during pyrolysis process. Copyright © 2016. Published by Elsevier B.V.

Solid solubility, phase transitions, thermal expansion, and compressibility in Sc{sub 1−x}Al{sub x}F{sub 3}

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

Morelock, Cody R.; Gallington, Leighanne C.; Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu

2015-02-15

With the goal of thermal expansion control, the synthesis and properties of Sc{sub 1−x}Al{sub x}F{sub 3} were investigated. The solubility limit of AlF{sub 3} in ScF{sub 3} at ∼1340 K is ∼50%. Solid solutions (x≤0.50) were characterized by synchrotron powder diffraction at ambient pressure between 100 and 900 K and at pressures <0.414 GPa while heating from 298 to 523 K. A phase transition from cubic to rhombohedral is observed. The transition temperature increases smoothly with Al{sup 3+} content, approaching 500 K at the solid solubility limit, and also upon compression at fixed Al{sup 3+} content. The slope of themore » pressure–temperature phase boundary is ∼0.5 K MPa{sup −1}, which is steep relative to that for most symmetry-lowering phase transitions in perovskites. The volume coefficient of thermal expansion (CTE) for the rhombohedral phase is strongly positive, but the cubic-phase CTE varies from negative (x<0.15) to near-zero (x=0.15) to positive (x>0.20) between ∼600 and 800 K. The cubic solid solutions elastically stiffen on heating, while Al{sup 3+} substitution causes softening at a given temperature. - Graphical abstract: The cubic-phase coefficient of thermal expansion for Sc{sub 1−x}Al{sub x}F{sub 3}(solubility limit ∼50% at ∼1340 K) becomes more positive with increased Al{sup 3+} substitution, but the average isothermal bulk modulus decreases (elastic softening). - Highlights: • The solubility limit of AlF{sub 3} in ScF{sub 3} at ∼1340 K is ∼50%. • The phase transition temperature of Sc{sub 1−x}Al{sub x}F{sub 3} increases smoothly with x. • The cubic-phase volume CTE varies from negative to positive with increasing x. • The cubic solid solutions elastically stiffen on heating. • Al{sup 3+} substitution causes softening at a given temperature.« less

Novel carbon-rich additives preparation by degradative solvent extraction of biomass wastes for coke-making.

PubMed

Zhu, Xianqing; Li, Xian; Xiao, Li; Zhang, Xiaoyong; Tong, Shan; Wu, Chao; Ashida, Ryuichi; Liu, Wenqiang; Miura, Kouichi; Yao, Hong

2016-05-01

In this work, two extracts (Soluble and Deposit) were produced by degradative solvent extraction of biomass wastes from 250 to 350°C. The feasibilities of using Soluble and Deposit as additives for coke-making were investigated for the first time. The Soluble and Deposit, having significantly higher carbon content, lower oxygen content and extremely lower ash content than raw biomasses. All Solubles and most of Deposits can melt completely at the temperature ranged from 80 to 120°C and 140 to 180°C, respectively. The additions of Soluble or Deposit into the coke-making coal significantly improved their thermoplastic properties with as high as 9°C increase of the plastic range. Furthermore, the addition of Deposit or Soluble also markedly enhanced the coke quality through increasing coke strength after reaction (CSR) and reducing coke reactivity index (CRI). Therefore, the Soluble and Deposit were proved to be good additives for coke-making. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sibutramine characterization and solubility, a theoretical study

NASA Astrophysics Data System (ADS)

Aceves-Hernández, Juan M.; Nicolás Vázquez, Inés; Hinojosa-Torres, Jaime; Penieres Carrillo, Guillermo; Arroyo Razo, Gabriel; Miranda Ruvalcaba, René

2013-04-01

Solubility data from sibutramine (SBA) in a family of alcohols were obtained at different temperatures. Sibutramine was characterized by using thermal analysis and X-ray diffraction technique. Solubility data were obtained by the saturation method. The van't Hoff equation was used to obtain the theoretical solubility values and the ideal solvent activity coefficient. No polymorphic phenomena were found from the X-ray diffraction analysis, even though this compound is a racemic mixture of (+) and (-) enantiomers. Theoretical calculations showed that the polarisable continuum model was able to reproduce the solubility and stability of sibutramine molecule in gas phase, water and a family of alcohols at B3LYP/6-311++G (d,p) level of theory. Dielectric constant, dipolar moment and solubility in water values as physical parameters were used in those theoretical calculations for explaining that behavior. Experimental and theoretical results were compared and good agreement was obtained. Sibutramine solubility increased from methanol to 1-octanol in theoretical and experimental results.

Wax encapsulation of water-soluble compounds for application in foods.

PubMed

Mellema, M; Van Benthum, W A J; Boer, B; Von Harras, J; Visser, A

2006-11-01

Water-soluble ingredients have been successfully encapsulated in wax using two preparation techniques. The first technique ('solid preparation') leads to relatively large wax particles. The second technique ('liquid preparation') leads to relatively small wax particles immersed in vegetable oil. On the first technique: stable encapsulation of water-soluble colourants (dissolved at low concentration in water) has been achieved making use of beeswax and PGPR. The leakage from the capsules, for instance of size 2 mm, is about 30% after 16 weeks storage in water at room temperature. To form such capsules a minimum wax mass of 40% relative to the total mass is needed. High amounts of salt or acids at the inside water phase causes more leaking, probably because of the osmotic pressure difference. Osmotic matching of inner and outer phase can lead to a dramatic reduction in leakage. Fat capsules are less suitable to incorporate water soluble colourants. The reason for this could be a difference in crystal structure (fat is less ductile and more brittle). On the second technique: stable encapsulation of water-soluble colourants (encapsulated in solid wax particles) has been achieved making use of carnauba wax. The leakage from the capsules, for instance of size 250 mm, is about 40% after 1 weeks storage in water at room temperature.

Solubility and Thermodynamics: An Introductory Experiment

NASA Astrophysics Data System (ADS)

Silberman, Robert G.

1996-05-01

This article describes a laboratory experiment suitable for high school or freshman chemistry students in which the solubility of potassium nitrate is determined at several different temperatures. The data collected is used to calculate the equilibrium constant, delta G, delta H, and delta S for dissolution reaction. The simplifying assumptions are noted in the article.

Fiberboard created using the natural adhesive properties of distillers dried grains with solubles

USDA-ARS?s Scientific Manuscript database

Distillers dried grains with solubles (DDGS) were employed as a bio-based resin/adhesive. DDGS were defatted with hexane, ball ground and screened prior to use. DDGS flour was mixed dry with Paulownia wood (PW) to make composites using the following conditions: temperature of 150-195 oC, PW particle...

Nutritional composition and solubility of edible bird nest (Aerodramus fuchiphagus)

NASA Astrophysics Data System (ADS)

Halimi, Nurfatin Mohd; Kasim, Zalifah Mohd; Babji, Abdul Salam

2014-09-01

Edible bird nest (EBN) produced by certain swiftlet species mainly, Aerodromus fuciphagus. The objectives of this study were to determine and compare the proximate and amino acid composition of EBN obtained from two regions in Peninsular Malaysia (Pahang-A & Terengganu-B). The solubility of edible bird nest with varying pH, temperature and time was also investigated in this study. The results showed that, the EBN contained crude protein accounted to 58.55% (A) and 55.48% (B), carbohydrate at22.28% (A) & 25.79% (B), moisture content 15.90% (A) & 15.87% (B), fat, 0.67% (A) & and 0.29% (B) and ash contents 2.60% (A) & 2.57% (B) respectively. The major amino acids found in edible bird nest EBN were Glutamic acid (9.61%), Aspartic acid (6.34%), Lysine (5.44 %) and also Leucine (5.30%). The total solubility of EBN was also found to be increased when the temperature was increased increase with distilled water yielding the highest total solubility of EBN compared to others buffer (different pH) solutions.

Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico

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

Birkle, P.; Pruess, K.; Xu, T.

Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubility. Clay swelling can also pose problems. During a preliminary waterflooding pilot project, the Poza Rica-Altamira oil field, bordering the Gulf coast in the eastern part of Mexico, experienced injectivity loss after five months ofmore » reinjection of formation waters into well AF-847 in 1999. Acidizing with HCl restored injectivity. We report on laboratory experiments and reactive chemistry modeling studies that were undertaken in preparation for long-term waterflooding at Agua Frma. Using analogous core plugs obtained from the same reservoir interval, laboratory coreflood experiments were conducted to examine sensitivity of mineral dissolution and precipitation effects to water composition. Native reservoir water, chemically altered waters, and distilled water were used, and temporal changes in core permeability, mineral abundances and aqueous concentrations of solutes were monitored. The experiments were simulated with the multi-phase, nonisothermal reactive transport code TOUGHREACT, and reasonable to good agreement was obtained for changes in solute concentrations. Clay swelling caused an additional impact on permeability behavior during coreflood experiments, whereas the modeled permeability depends exclusively on chemical processes. TOUGHREACT was then used for reservoir-scale simulation of injecting ambient-temperature water (30 C, 86 F) into a reservoir with initial temperature of 80 C (176 F). Untreated native reservoir water was found to cause serious porosity and permeability reduction due to calcite precipitation, which is promoted by the retrograde solubility of this mineral. Using treated water that performed well in the laboratory flow experiments was found to avoid excessive precipitation, and allowed injection to proceed.« less

Dissolution-modulating mechanism of pH modifiers in solid dispersion containing weakly acidic or basic drugs with poor water solubility.

PubMed

Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Lee, Kyoung-Ho; Kim, Dong-Jin; Lee, Beom-Jin

2010-05-01

Although the solid dispersion method has been known to increase the dissolution rate of poorly water-soluble drugs by dispersing them in hydrophilic carriers, one obstacle of the solid dispersion method is its limited solubilization capacity, especially for pH-dependent soluble drugs. pH-modified solid dispersion, in which pH modifiers are incorporated, may be a useful method for increasing the dissolution rate of weakly acidic or basic drugs. Sufficient research, including the most recent reports, was undertaken in this review. How could the inclusion of the pH the pH modifiers in the solid dispersion system change drug structural behaviors, molecular interactions, microenvironmental pH, and/or release rate of pH modifiers, relating with the enhanced dissolution of weakly acidic or weakly basic drugs with poor water solubility? These questions have been investigated to determine the dissolution-modulating mechanism of pH modifiers in solid dispersion containing weakly acidic or basic drugs. It is believed that step-by-step mechanistic approaches could provide the ultimate solution for solubilizing several poorly water-soluble drugs with pH-dependent solubility from a solid dispersion system, as well as provide ideas for developing future dosage systems.

The impacts of surface polarity on the solubility of nanoparticle

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

Zhu, Jianzhuo; Su, Jiguo, E-mail: jiguosu@ysu.edu.cn; Ou, Xinwen

In order to study the dependence of water solubility and hydration behavior of nanoparticles on their surface polarity, we designed polar nanoparticles with varying surface polarity by assigning atomic partial charge to the surface of C60. The water solubility of the nanoparticle is enhanced by several orders of magnitude after the introduction of surface polarity. Nevertheless, when the atomic partial charge grows beyond a certain value (q{sub M}), the solubility continuously decreases to the level of nonpolar nanoparticle. It should be noted that such q{sub M} is comparable with atomic partial charge of a variety of functional groups. The hydrationmore » behaviors of nanoparticles were then studied to investigate the non-monotonic dependence of solubility on the surface polarity. The interaction between the polar nanoparticle and the hydration water is stronger than the nonpolar counterpart, which should facilitate the dissolution of the nanoparticles. On the other hand, the surface polarity also reduces the interaction of hydration water with the other water molecules and enhances the interaction between the nanoparticles which may hinder their dispersion. Besides, the introduction of surface polarity disturbs and even rearranges the hydration structure of nonpolar nanoparticle. Interestingly, the polar nanoparticle with less ordered hydration structure tends to have higher water solubility.« less

Secretome weaponries of Cochliobolus lunatus interacting with potato leaf at different temperature regimes reveal a CL[xxxx]LHM - motif

PubMed Central

2014-01-01

Background Plant and animal pathogenic fungus Cochliobolus lunatus cause great economic damages worldwide every year. C. lunatus displays an increased temperature dependent-virulence to a wide range of hosts. Nonetheless, this phenomenon is poorly understood due to lack of insights on the coordinated secretome weaponries produced by C. lunatus under heat-stress conditions on putative hosts. To understand the mechanism better, we dissected the secretome of C. lunatus interacting with potato (Solanum tuberosum L.) leaf at different temperature regimes. Results C. lunatus produced melanized colonizing hyphae in and on potato leaf, finely modulated the ambient pH as a function of temperature and secreted diverse set of proteins. Using two dimensional gel electrophoresis (2-D) and mass spectrometry (MS) technology, we observed discrete secretomes at 20°C, 28°C and 38°C. A total of 21 differentially expressed peptide spots and 10 unique peptide spots (that did not align on the gels) matched with 28 unique protein models predicted from C. lunatus m118 v.2 genome peptides. Furthermore, C. lunatus secreted peptides via classical and non-classical pathways related to virulence, proteolysis, nucleic acid metabolism, carbohydrate metabolism, heat stress, signal trafficking and some with unidentified catalytic domains. Conclusions We have identified a set of 5 soluble candidate effectors of unknown function from C. lunatus secretome weaponries against potato crop at different temperature regimes. Our findings demonstrate that C. lunatus has a repertoire of signature secretome which mediates thermo-pathogenicity and share a leucine rich “CL[xxxx]LHM”-motif. Considering the rapidly evolving temperature dependent-virulence and host diversity of C. lunatus, this data will be useful for designing new protection strategies. PMID:24650331

Secretome weaponries of Cochliobolus lunatus interacting with potato leaf at different temperature regimes reveal a CL[xxxx]LHM - motif.

PubMed

Louis, Bengyella; Waikhom, Sayanika Devi; Roy, Pranab; Bhardwaj, Pardeep Kumar; Singh, Mohendro Wakambam; Goyari, Sailendra; Sharma, Chandradev K; Talukdar, Narayan Chandra

2014-03-20

Plant and animal pathogenic fungus Cochliobolus lunatus cause great economic damages worldwide every year. C. lunatus displays an increased temperature dependent-virulence to a wide range of hosts. Nonetheless, this phenomenon is poorly understood due to lack of insights on the coordinated secretome weaponries produced by C. lunatus under heat-stress conditions on putative hosts. To understand the mechanism better, we dissected the secretome of C. lunatus interacting with potato (Solanum tuberosum L.) leaf at different temperature regimes. C. lunatus produced melanized colonizing hyphae in and on potato leaf, finely modulated the ambient pH as a function of temperature and secreted diverse set of proteins. Using two dimensional gel electrophoresis (2-D) and mass spectrometry (MS) technology, we observed discrete secretomes at 20°C, 28°C and 38°C. A total of 21 differentially expressed peptide spots and 10 unique peptide spots (that did not align on the gels) matched with 28 unique protein models predicted from C. lunatus m118 v.2 genome peptides. Furthermore, C. lunatus secreted peptides via classical and non-classical pathways related to virulence, proteolysis, nucleic acid metabolism, carbohydrate metabolism, heat stress, signal trafficking and some with unidentified catalytic domains. We have identified a set of 5 soluble candidate effectors of unknown function from C. lunatus secretome weaponries against potato crop at different temperature regimes. Our findings demonstrate that C. lunatus has a repertoire of signature secretome which mediates thermo-pathogenicity and share a leucine rich "CL[xxxx]LHM"-motif. Considering the rapidly evolving temperature dependent-virulence and host diversity of C. lunatus, this data will be useful for designing new protection strategies.

High carrier mobility of Sn-doped polycrystalline-Ge films on insulators by thickness-dependent low-temperature solid-phase crystallization

NASA Astrophysics Data System (ADS)

Sadoh, Taizoh; Kai, Yuki; Matsumura, Ryo; Moto, Kenta; Miyao, Masanobu

2016-12-01

To realize the advanced thin-film transistors (TFTs), high-carrier-mobility semiconductor films on insulator structures should be fabricated with low-temperature processing conditions (≤500 °C). To achieve this, we investigated the solid-phase crystallization of amorphous-GeSn films on insulating substrates under a wide range of Sn concentrations (0%-20%), film thicknesses (30-500 nm), and annealing temperatures (380-500 °C). Our results reveal that a Sn concentration close to the solid solubility of Sn in Ge (˜2%) is effective in increasing the grain-size of poly-GeSn. In addition, we discovered that the carrier mobility depends on the film thickness, where the mobilities are determined by the counterbalance between two different carrier scattering mechanisms. Here, vacancy-related defects dominate the carrier scattering near the insulating substrates (≤˜120 nm), and grain-size determined by bulk nucleation dominates the grain-boundary scattering of thick films (≥˜200 nm). Consequently, we obtained the maximum mobilities in samples with a Sn concentration of 2% and a film thickness of 200 nm. The effect of increasing the grain-size of poly-GeSn by lowering the annealing temperature was also clarified. By combining these results, a very high carrier mobility of 320 cm2/Vs was obtained at a low temperature of 380 °C. This mobility is about 2.5 times as high as previously reported data for Ge and GeSn films grown at low temperatures (≤500 °C). Our technique therefore opens up the possibility of high-speed TFTs for use in the next generation of electronics.

The effect of air temperature on the sappan wood extract drying

NASA Astrophysics Data System (ADS)

Djaeni, M.; Triyastuti, M. S.; Asiah, N.; Annisa, A. N.; Novita, D. A.

2015-12-01

The sappan wood extract contain natural colour called brazilin that can be used as a food colouring and antioxidant. The product is commonly found as a dry extract powder for consummer convenience. The spray dryer with air dehumidification can be an option to retain the colour and antioxidant agent. This paper discusses the effect of air temperature on sappan wood extract drying that was mixed with maltodextrin. As responses, the particle size, final moisture content, and extract solubility degradation were observed. In all cases, the process conducted in temperature ranging 90 - 110°C can retain the brazilin quality as seen in solubility and particle size. In addition, the sappan wood extract can be fully dried with moisture content below 2%. Moreover, with the increase of air temperature, the particle size of dry extract can be smaller.

The influence of growth environment on the crystallization of nortriptyline hydrochloride, a tricyclic antidepressant

NASA Astrophysics Data System (ADS)

MacCalman, M. L.; Roberts, K. J.; Hendriksen, B. A.

1993-03-01

The preparation of the nortriptyline hydrochloride, an important pharmaceutical product, by crystallization from both alcohol and aqueous solutions is presented. At low temperatures this material shows a higher solubility in absolute alcohol compared to aqueous solutions in a trend which reverses at higher temperatures. Examination of crystals prepared from alcohol solutions reveal essentially a needle-like crystal habit which is in excellent agreement with morphological predictions based on the bulk crystallographic structure. In contrast crystals prepared from aqueous solution at high temperatures reveal a particulate structure dominated by heavily agglomerated crystallites with plate-like morphology. When this material is crystallized at the lower temperatures, where the solubility curve is steep, X-ray and thermal analysis appear to show that crystallization results in a new polymorphic structure associated with a less agglomerated product.

Solubility Enhancement of Raloxifene Using Inclusion Complexes and Cogrinding Method

PubMed Central

Patil, Payal H.; Belgamwar, Veena S.; Patil, Pratibha R.; Surana, Sanjay J.

2013-01-01

The objective of the present work was to enhance the solubility and dissolution of practically water-insoluble drug raloxifene HCl (RLX), for the same two approaches that were used. In the first approach, drug was kneaded with hydroxypropyl-β-cyclodextrin (HPβCD), and in the second one drug was cogrinded with modified guar gum (MGG). The drug-cyclodextrin complex and drug-MGG cogrind mixtures were characterized by differential scanning calorimetry, X-ray diffraction studies, scanning electron microscopy, and Fourier transform infrared spectroscopy. The solubility and dissolution study reveals that solubility and dissolution rate of RLX remarkably increased in both methods. It was concluded that the prepared inclusion complex showed a remarkable increase in solubility and dissolution of poorly water-soluble drug raloxifene. In the cogrinding mixture, a natural modified gum is used as a surfactant and enhances the solubility and dissolution of RLX without requiring addition of organic solvent or high temperature for its preparation; thus, process is less cumbersome and cost effective. But when both methods were compared; HPβCD complexation method showed significant enhancement of drug solubility. PMID:26555984

IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 2. Light Lanthanides (Ce–Eu)

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

Mioduski, Tomasz; Gumiński, Cezary, E-mail: cegie@chem.uw.edu.pl; Zeng, Dewen, E-mail: dewen-zeng@hotmail.com

This is the second part of the volume devoted to the evaluation of experimental solubility data for rare earth metal (REM) fluorides in water as well as in aqueous ternary and multicomponent systems. Fluorides of Ce, Pr, Nd, Pm, Sm, and Eu (so-called light lanthanides), as the main solutes, are covered in the present part, which has thorough coverage of the experimental literature through the end of 2012. The experimentally unknown solubility value for PmF{sub 3} in water was predicted by an interpolation of the solubility values for NdF{sub 3} and SmF{sub 3} at 298 K. General features of themore » systems, such as the nature of the equilibrium solid phases, solubility as a function of temperature, influence of ionic strength, pH, mixed solvent medium on the solubility, quality of the solubility results, and solubility as a function of REM atomic number, have already been presented in Part 1 of the volume.« less

Heat and corrosion resistant cast CF8C stainless steel with improved high temperature strength and ductility

DOEpatents

Maziasz, Philip J.; McGreevy, Tim; Pollard, Michael James; Siebenaler, Chad W.; Swindeman, Robert W.

2006-12-26

A CF8C type stainless steel alloy and articles formed therefrom containing about 18.0 weight percent to about 22.0 weight percent chromium and 11.0 weight percent to about 14.0 weight percent nickel; from about 0.05 weight percent to about 0.15 weight percent carbon; from about 2.0 weight percent to about 10.0 weight percent manganese; and from about 0.3 weight percent to about 1.5 weight percent niobium. The present alloys further include less than 0.15 weight percent sulfur which provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. The disclosed alloys also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon.

Heat and corrosion resistant cast CF8C stainless steel with improved high temperature strength and ductility

DOEpatents

Maziasz, Philip J.; McGreevy, Tim; Pollard, Michael James; Siebenaler, Chad W.; Swindeman, Robert W.

2010-08-17

A CF8C type stainless steel alloy and articles formed therefrom containing about 18.0 weight percent to about 22.0 weight percent chromium and 11.0 weight percent to about 14.0 weight percent nickel; from about 0.05 weight percent to about 0.15 weight percent carbon; from about 2.0 weight percent to about 10.0 weight percent manganese; and from about 0.3 weight percent to about 1.5 weight percent niobium. The present alloys further include less than 0.15 weight percent sulfur which provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. The disclosed alloys also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon.

[Effects of tree species fine root decomposition on soil active organic carbon].

PubMed

Liu, Yan; Wang, Si-Long; Wang, Xiao-Wei; Yu, Xiao-Jun; Yang, Yue-Jun

2007-03-01

With incubation test, this paper studied the effects of fine root decomposition of Alnus cremastogyne, Cunninghamia lanceolata and Michelia macclurei on the content of soil active organic carbon at 9 degrees C , 14 degrees C , 24 degrees C and 28 degrees C. The results showed that the decomposition rate of fine root differed significantly with test tree species, which was decreased in the order of M. macclurei > A. cremastogyne > C. lanceolata. The decomposition rate was increased with increasing temperature, but declined with prolonged incubation time. Fine root source, incubation temperature, and incubation time all affected the contents of soil microbial biomass carbon and water-soluble organic carbon. The decomposition of fine root increased soil microbial biomass carbon and water-soluble organic carbon significantly, and the effect decreased in the order of M. macclurei > A. cremastogyne > C. lanceolata. Higher contents of soil microbial biomass carbon and water-soluble organic carbon were observed at medium temperature and middle incubation stage. Fine root decomposition had less effect on the content of soil readily oxidized organic carbon.

Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation

DOE PAGES

Jensen, Mallory A.; Morishige, Ashley E.; Chakraborty, Sagnik; ...

2018-02-02

Light- and elevated temperature-induced degradation (LeTID) is a detrimental effect observed under operating conditions in p-type multicrystalline silicon (mc-Si) solar cells. In this paper, we employ synchrotron-based techniques to study the dissolution of precipitates due to different firing processes at grain boundaries in LeTID-affected mc-Si. The synchrotron measurements show clear dissolution of collocated metal precipitates during firing. We compare our observations with degradation behavior in the same wafers. The experimental results are complemented with process simulations to provide insight into the change in bulk point defect concentration due to firing. Several studies have proposed that LeTID is caused by metal-richmore » precipitate dissolution during contact firing, and we find that the solubility and diffusivity are promising screening metrics to identify metals that are compatible with this hypothesis. While slower and less soluble elements (e.g., Fe and Cr) are not compatible according to our simulations, the point defect concentrations of faster and more soluble elements (e.g., Cu and Ni) increase after a high-temperature firing process, primarily due to emitter segregation rather than precipitate dissolution. Finally, these results are a useful complement to lifetime spectroscopy techniques, and can be used to evaluate additional candidates in the search for the root cause of LeTID.« less

Solubility and Diffusivity: Important Metrics in the Search for the Root Cause of Light- and Elevated Temperature-Induced Degradation

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

Jensen, Mallory A.; Morishige, Ashley E.; Chakraborty, Sagnik

Light- and elevated temperature-induced degradation (LeTID) is a detrimental effect observed under operating conditions in p-type multicrystalline silicon (mc-Si) solar cells. In this paper, we employ synchrotron-based techniques to study the dissolution of precipitates due to different firing processes at grain boundaries in LeTID-affected mc-Si. The synchrotron measurements show clear dissolution of collocated metal precipitates during firing. We compare our observations with degradation behavior in the same wafers. The experimental results are complemented with process simulations to provide insight into the change in bulk point defect concentration due to firing. Several studies have proposed that LeTID is caused by metal-richmore » precipitate dissolution during contact firing, and we find that the solubility and diffusivity are promising screening metrics to identify metals that are compatible with this hypothesis. While slower and less soluble elements (e.g., Fe and Cr) are not compatible according to our simulations, the point defect concentrations of faster and more soluble elements (e.g., Cu and Ni) increase after a high-temperature firing process, primarily due to emitter segregation rather than precipitate dissolution. Finally, these results are a useful complement to lifetime spectroscopy techniques, and can be used to evaluate additional candidates in the search for the root cause of LeTID.« less

The Effect of Heat Stress on Tomato Pollen Characteristics is Associated with Changes in Carbohydrate Concentration in the Developing Anthers

PubMed Central

PRESSMAN, ETAN; PEET, MARY M.; PHARR, D. MASON

2002-01-01

Continuous exposure of tomato ‘Trust’ to high temperatures (day/night temperatures of 32/26 °C) markedly reduced the number of pollen grains per flower and decreased viability. The effect of heat stress on pollen viability was associated with alterations in carbohydrate metabolism in various parts of the anther during its development. Under control, favourable temperature conditions (28/22 °C), starch accumulated in the pollen grains, where it reached a maximum value 3 d before anthesis; it then diminished towards anthesis. During anther development, the concentration of total soluble sugars gradually increased in the anther walls and in the pollen grains (but not in the locular fluid), reaching a maximum at anthesis. Continuous exposure of the plants to high temperatures (32/26 °C) prevented the transient increase in starch concentration and led to decreases in the concentrations of soluble sugars in the anther walls and the pollen grains. In the locular fluid, however, a higher soluble sugar concentration was detected under the high‐temperature regime throughout anther development. These results suggest that a major effect of heat stress on pollen development is a decrease in starch concentration 3 d before anthesis, which results in a decreased sugar concentration in the mature pollen grains. These events possibly contribute to the decreased pollen viability in tomato. PMID:12466104

Use of Response Surface Methodology to Optimize Culture Conditions for Hydrogen Production by an Anaerobic Bacterial Strain from Soluble Starch

NASA Astrophysics Data System (ADS)

Kieu, Hoa Thi Quynh; Nguyen, Yen Thi; Dang, Yen Thi; Nguyen, Binh Thanh

2016-05-01

Biohydrogen is a clean source of energy that produces no harmful byproducts during combustion, being a potential sustainable energy carrier for the future. Therefore, biohydrogen produced by anaerobic bacteria via dark fermentation has attracted attention worldwide as a renewable energy source. However, the hydrogen production capability of these bacteria depends on major factors such as substrate, iron-containing hydrogenase, reduction agent, pH, and temperature. In this study, the response surface methodology (RSM) with central composite design (CCD) was employed to improve the hydrogen production by an anaerobic bacterial strain isolated from animal waste in Phu Linh, Soc Son, Vietnam (PL strain). The hydrogen production process was investigated as a function of three critical factors: soluble starch concentration (8 g L-1 to 12 g L-1), ferrous iron concentration (100 mg L-1 to 200 mg L-1), and l-cysteine concentration (300 mg L-1 to 500 mg L-1). RSM analysis showed that all three factors significantly influenced hydrogen production. Among them, the ferrous iron concentration presented the greatest influence. The optimum hydrogen concentration of 1030 mL L-1 medium was obtained with 10 g L-1 soluble starch, 150 mg L-1 ferrous iron, and 400 mg L-1 l-cysteine after 48 h of anaerobic fermentation. The hydrogen concentration produced by the PL strain was doubled after using RSM. The obtained results indicate that RSM with CCD can be used as a technique to optimize culture conditions for enhancement of hydrogen production by the selected anaerobic bacterial strain. Hydrogen production from low-cost organic substrates such as soluble starch using anaerobic fermentation methods may be one of the most promising approaches.

Solubility, Stability, Physicochemical Characteristics and In Vitro Ocular Tissue Permeability of Hesperidin: a Natural Bioflavonoid

PubMed Central

Majumdar, Soumyajit; Srirangam, Ramesh

2008-01-01

Purpose Hesperidin holds potential in treating age-related macular degeneration, cataract and diabetic retinopathy. The aim of this study, constituting the first step towards efficient ocular delivery of hesperidin, was to determine its physicochemical properties and in vitro ocular tissue permeability. Methods pH dependent aqueous solubility and stability were investigated following standard protocols. Permeability of hesperidin across excised rabbit cornea, sclera, and sclera plus retinal pigmented epithelium (RPE) was determined using a side-bi-side diffusion apparatus. Results Hesperidin demonstrated poor, pH independent, aqueous solubility. Solubility improved dramatically in the presence of 2-hydroxypropyl-beta-cyclodextrin (HP-β-CD) and the results supported 1:1 complex formation. Solutions were stable in the pH and temperature (25, 40°C) conditions tested, except for samples stored at pH 9. Transcorneal permeability in the apical-basal and basal-apical directions was 1.11±0.86×10−6 and 1.16±0.05×10−6 cm/s, respectively. The scleral tissue was more permeable (10.2±2.1×10−6cm/s). However, permeability across sclera/choroid/RPE in the sclera to retina and retina to sclera direction was 0.82±0.69×10−6, 1.52±0.78×10−6 cm/s, respectively, demonstrating the barrier properties of the RPE. Conclusion Our results suggest that stable ophthalmic solutions of hesperidin can be prepared and that hesperidin can efficiently permeate across the corneal tissue. Further investigation into its penetration into the back-of-the eye ocular tissues is warranted. PMID:18810327

Formulation, functional evaluation and ex vivo performance of thermoresponsive soluble gels - A platform for therapeutic delivery to mucosal sinus tissue.

PubMed

Pandey, Preeti; Cabot, Peter J; Wallwork, Benjamin; Panizza, Benedict J; Parekh, Harendra S

2017-01-01

Mucoadhesive in situ gelling systems (soluble gels) have received considerable attention recently as effective stimuli-transforming vectors for a range of drug delivery applications. Considering this fact, the present work involves systematic formulation development, optimization, functional evaluation and ex vivo performance of thermosensitive soluble gels containing dexamethasone 21-phosphate disodium salt (DXN) as the model therapeutic. A series of in situ gel-forming systems comprising the thermoreversible polymer poloxamer-407 (P407), along with hydroxypropyl methyl cellulose (HPMC) and chitosan were first formulated. The optimized soluble gels were evaluated for their potential to promote greater retention at the mucosal surface, for improved therapeutic efficacy, compared to existing solution/suspension-based steroid formulations used clinically. Optimized soluble gels demonstrated a desirable gelation temperature with Newtonian fluid behaviour observed under storage conditions (4-8°C), and pseudoplastic fluid behaviour recorded at nasal cavity/sinus temperature (≈34°C). The in vitro characterization of formulations including rheological evaluation, textural analysis and mucoadhesion studies of the gel form were investigated. Considerable improvement in mechanical properties and mucoadhesion was observed with incorporation of HPMC and chitosan into the gelling systems. The lead poloxamer-based soluble gels, PGHC4 and PGHC7, which were carried through to ex vivo permeation studies displayed extended drug release profiles in conditions mimicking the human nasal cavity, which indicates their suitability for treating a range of conditions affecting the nasal cavity/sinuses. Copyright © 2016 Elsevier B.V. All rights reserved.

A theoretical insight into H accumulation and bubble formation by applying isotropic strain on the W-H system under a fusion environment

NASA Astrophysics Data System (ADS)

Han, Quan-Fu; Liu, Yue-Lin; Zhang, Ying; Ding, Fang; Lu, Guang-Hong

2018-04-01

The solubility and bubble formation of hydrogen (H) in tungsten (W) are crucial factors for the application of W as a plasma-facing component under a fusion environment, but the data and mechanism are presently scattered, indicating some important factors might be neglected. High-energy neutron-irradiated W inevitably causes a local strain, which may change the solubility of H in W. Here, we performed first-principles calculations to predict the H solution behaviors under isotropic strain combined with temperature effect in W and found that the H solubility in interstitial lattice can be promoted/impeded by isotropic tensile/compressive strain over the temperature range 300-1800 K. The calculated H solubility presents good agreement with the experiment. Together, our previous results of anisotropic strain, except for isotropic compression, both isotropic tension and anisotropic tension/compression enhance H solution so as to reveal an important physical implication for H accumulation and bubble formation in W: strain can enhance H solubility, resulting in the preliminary nucleation of H bubble that further causes the local strain of W lattice around H bubble, which in turn improves the H solubility at the strained region that promotes continuous growth of the H bubble via a chain-reaction effect in W. This result can also interpret the H bubble formation even if no radiation damage is produced in W exposed to low-energy H plasma.

Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

NASA Technical Reports Server (NTRS)

Iraci, L. T.; Essin, A. M.; Golden, D. M.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

Potentiometric and spectrophotometric study of the stability of magnesium carbonate and bicarbonate ion pairs to 150 °C and aqueous inorganic carbon speciation and magnesite solubility

NASA Astrophysics Data System (ADS)

Stefánsson, Andri; Bénézeth, Pascale; Schott, Jacques

2014-08-01

The formation constants of magnesium bicarbonate and carbonate ion pairs have been experimentally determined in dilute hydrothermal solutions to 150 °C. Two experimental approaches were applied, potentiometric acid-base titrations at 10-60 °C and spectrophotometric pH measurements using two pH indicators, 2-naphthol and 4-nitrophenol, at 25 and 80-150 °C. At a given temperature, the first and second ionization constants of carbonic acid (K1, K2) and the ion pair formation constants for MgHCO3+(aq) (KMgHCO3+) and MgCO3(aq) (KMgCO3) were simultaneously fitted to the data. Results of this study compare well with previously determined values of K1 and K2. The formation constants of MgHCO3+(aq) and MgCO3(aq) ion pairs increased significantly with increasing temperature, with values of logKMgHCO3+ = 1.14 and 1.75 and of logKMgCO3 = 2.86 and 3.48 at 10 °C and 100 °C, respectively. These ion pairs are important aqueous species under neutral to alkaline conditions in moderately dilute to concentrated Mg-containing solutions, with MgCO3(aq) predominating over CO32-(aq) in solutions at pH >8. The predominance of magnesium carbonate over carbonate is dependent on the concentration of dissolved magnesium and the ratio of magnesium over carbonate. With increasing temperature and at alkaline pH, brucite solubility further reduced the magnesium concentration to levels below 1 mmol kg-1, thus limiting availability of Mg2+(aq) for magnesite precipitation.

Computations on Internal Blast from Titanium-Cased Charges in Air

DTIC Science & Technology

1984-07-01

formation and considerable temperature- dependent polymorphic transition . Oxygen is soluble in titanium metal to the extent of about 25 atom-percent, yielding...15 CSH8N4O1 2 NC Nitrocellulose, 13.3% N; -812.9 +3 C6H7N2.5010 HMX symn-Cyclotetramnethylene- + 77.4 0 tetranitramine, C4HSNBO8 Pentolite 50% PETN, 50...TNT; -97.9 -5 C6.1 6H6 .2 5N3.41085. Comp 8 65% RDX , 35% TNT; + 11.47 -9 C1 .96H2. 53N2.2202.68 TNT 2,4,6-Trinitrotoluene, +30.7 -25 p C7R 5N306 N2

Investigation of attractive and repulsive interactions associated with ketones in supercritical CO2, based on Raman spectroscopy and theoretical calculations.

PubMed

Kajiya, Daisuke; Saitow, Ken-ichi

2013-08-07

Carbonyl compounds are solutes that are highly soluble in supercritical CO2 (scCO2). Their solubility governs the efficiency of chemical reactions, and is significantly increased by changing a chromophore. To effectively use scCO2 as solvent, it is crucial to understand the high solubility of carbonyl compounds, the solvation structure, and the solute-solvent intermolecular interactions. We report Raman spectroscopic data, for three prototypical ketones dissolved in scCO2, and four theoretical analyses. The vibrational Raman spectra of the C=O stretching modes of ketones (acetone, acetophenone, and benzophenone) were measured in scCO2 along the reduced temperature Tr = T∕Tc = 1.02 isotherm as a function of the reduced density ρr = ρ∕ρc in the range 0.05-1.5. The peak frequencies of the C=O stretching modes shifted toward lower energies as the fluid density increased. The density dependence was analyzed by using perturbed hard-sphere theory, and the shift was decomposed into attractive and repulsive energy components. The attractive energy between the ketones and CO2 was up to nine times higher than the repulsive energy, and its magnitude increased in the following order: acetone < acetophenone < benzophenone. The Mulliken charges of the three solutes and CO2 molecules obtained by using quantum chemistry calculations described the order of the magnitude of the attractive energy and optimized the relative configuration between each solute and CO2. According to theoretical calculations for the dispersion energy, the dipole-induced-dipole interaction energy, and the frequency shift due to their interactions, the experimentally determined attractive energy differences in the three solutes were attributed to the dispersion energies that depended on a chromophore attached to the carbonyl groups. It was found that the major intermolecular interaction with the attractive shift varied from dipole-induced dipole to dispersion depending on the chromophore in the ketones in scCO2. As the common conclusion for the Raman spectral measurements and the four theoretical calculations, solute polarizability, modified by the chromophore, was at the core of the solute-solvent interactions of the ketones in scCO2.

Solubility of caffeine from green tea in supercritical CO2: a theoretical and empirical approach.

PubMed

Gadkari, Pravin Vasantrao; Balaraman, Manohar

2015-12-01

Decaffeination of fresh green tea was carried out with supercritical CO2 in the presence of ethanol as co-solvent. The solubility of caffeine in supercritical CO2 varied from 44.19 × 10(-6) to 149.55 × 10(-6) (mole fraction) over a pressure and temperature range of 15 to 35 MPa and 313 to 333 K, respectively. The maximum solubility of caffeine was obtained at 25 MPa and 323 K. Experimental solubility data were correlated with the theoretical equation of state models Peng-Robinson (PR), Soave Redlich-Kwong (SRK), and Redlich-Kwong (RK). The RK model had regressed experimental data with 15.52 % average absolute relative deviation (AARD). In contrast, Gordillo empirical model regressed the best to experimental data with only 0.96 % AARD. Under supercritical conditions, solubility of caffeine in tea matrix was lower than the solubility of pure caffeine. Further, solubility of caffeine in supercritical CO2 was compared with solubility of pure caffeine in conventional solvents and a maximum solubility 90 × 10(-3) mol fraction was obtained with chloroform.

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

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Structural hot spots for the solubility of globular proteins

PubMed Central

Ganesan, Ashok; Siekierska, Aleksandra; Beerten, Jacinte; Brams, Marijke; Van Durme, Joost; De Baets, Greet; Van der Kant, Rob; Gallardo, Rodrigo; Ramakers, Meine; Langenberg, Tobias; Wilkinson, Hannah; De Smet, Frederik; Ulens, Chris; Rousseau, Frederic; Schymkowitz, Joost

2016-01-01

Natural selection shapes protein solubility to physiological requirements and recombinant applications that require higher protein concentrations are often problematic. This raises the question whether the solubility of natural protein sequences can be improved. We here show an anti-correlation between the number of aggregation prone regions (APRs) in a protein sequence and its solubility, suggesting that mutational suppression of APRs provides a simple strategy to increase protein solubility. We show that mutations at specific positions within a protein structure can act as APR suppressors without affecting protein stability. These hot spots for protein solubility are both structure and sequence dependent but can be computationally predicted. We demonstrate this by reducing the aggregation of human α-galactosidase and protective antigen of Bacillus anthracis through mutation. Our results indicate that many proteins possess hot spots allowing to adapt protein solubility independently of structure and function. PMID:26905391

Drug Solubility: Importance and Enhancement Techniques

PubMed Central

Savjani, Ketan T.; Gajjar, Anuradha K.; Savjani, Jignasa K.

2012-01-01

Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous system, is one of the important parameters to achieve desired concentration of drug in systemic circulation for desired (anticipated) pharmacological response. Low aqueous solubility is the major problem encountered with formulation development of new chemical entities as well as for the generic development. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Solubility is a major challenge for formulation scientist. Any drug to be absorbed must be present in the form of solution at the site of absorption. Various techniques are used for the enhancement of the solubility of poorly soluble drugs which include physical and chemical modifications of drug and other methods like particle size reduction, crystal engineering, salt formation, solid dispersion, use of surfactant, complexation, and so forth. Selection of solubility improving method depends on drug property, site of absorption, and required dosage form characteristics. PMID:22830056

Effects of heat treating PM Rene' 95 slightly below the gamma-prime solvus

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.

1977-01-01

An investigation was performed on As-HIP Rene' 95 to obtain additional information on the variation of the amount of gamma-prime with solutioning temperatures near the gamma-prime solvus temperature and the resulting effects on tensile and stress rupture strengths of As-HIP Rene' 95. The amount of gamma-prime phase was found to increase at a rate of about 0.5% per degree Celsius as the temperature decreased from the solvus temperature to about 50 C below the gamma-prime solvus temperature. The change in the amount of gamma-prime phase with decreasing solutioning temperature was observed to be primarily associated with decreasing solubilities of Al+Ti+Nb and increasing solubility of Cr in the gamma phase. For As-HIP Rene' 95 solutioned at either 1107 or 1135 C and subsequently water-quenched and double aged for 4 hours at 815 C followed by 24 hours at 650 C, the higher solution temperature resulted in significantly greater yield strengths at room temperature and 650 C as well as a greater room-temperature ultimate strength. Also, longer stress rupture lives at 650 C were associated with the higher solution temperature.

Using liquid and solid state NMR and photoluminescence to study the synthesis and solubility properties of amine capped silicon nanoparticles.

PubMed

Giuliani, J R; Harley, S J; Carter, R S; Power, P P; Augustine, M P

2007-08-01

Water soluble silicon nanoparticles were prepared by the reaction of bromine terminated silicon nanoparticles with 3-(dimethylamino)propyl lithium and characterized with liquid and solid state nuclear magnetic resonance (NMR) and photoluminescence (PL) spectroscopies. The surface site dependent 29Si chemical shifts and the nuclear spin relaxation rates from an assortment of 1H-29Si heteronuclear solid state NMR experiments for the amine coated reaction product are consistent with both the 1H and 13C liquid state NMR results and routine transmission electron microscopy, ultra-violet/visible, and Fourier transform infrared measurements. PL was used to demonstrate the pH dependent solubility properties of the amine passivated silicon nanoparticles.

A spectrum of exercise training reduces soluble Aβ in a dose-dependent manner in a mouse model of Alzheimer's disease.

PubMed

Moore, Kaitlin M; Girens, Renee E; Larson, Sara K; Jones, Maria R; Restivo, Jessica L; Holtzman, David M; Cirrito, John R; Yuede, Carla M; Zimmerman, Scott D; Timson, Benjamin F

2016-01-01

Physical activity has long been hypothesized to influence the risk and pathology of Alzheimer's disease. However, the amount of physical activity necessary for these benefits is unclear. We examined the effects of three months of low and high intensity exercise training on soluble Aβ40 and Aβ42 levels in extracellular enriched fractions from the cortex and hippocampus of young Tg2576 mice. Low (LOW) and high (HI) intensity exercise training animals ran at speeds of 15m/min on a level treadmill and 32 m/min at a 10% grade, respectively for 60 min per day, five days per week, from three to six months of age. Sedentary mice (SED) were placed on a level, non-moving, treadmill for the same duration. Soleus muscle citrate synthase activity increased by 39% in the LOW group relative to SED, and by 71% in the HI group relative to LOW, indicating an exercise training effect in these mice. Soluble Aβ40 concentrations decreased significantly in an exercise training dose-dependent manner in the cortex. In the hippocampus, concentrations were decreased significantly in the HI group relative to LOW and SED. Soluble Aβ42 levels also decreased significantly in an exercise training dose-dependent manner in both the cortex and hippocampus. Five proteins involved in Aβ clearance (neprilysin, IDE, MMP9, LRP1 and HSP70) were elevated by exercise training with its intensity playing a role in each case. Our data demonstrate that exercise training reduces extracellular soluble Aβ in the brains of Tg2576 mice in a dose-dependent manner through an up-regulation of Aβ clearance. Copyright © 2015 Elsevier Inc. All rights reserved.

Improving solubility of Shewanella oneidensis MR-1 and Clostridium thermocellum JW-20 proteins expressed into Esherichia coli.

PubMed

Kataeva, Irina; Chang, Jessie; Xu, Hao; Luan, Chi-Hao; Zhou, Jizhong; Uversky, Vladimir N; Lin, Dawei; Horanyi, Peter; Liu, Z J; Ljungdahl, Lars G; Rose, John; Luo, Ming; Wang, Bi-Cheng

2005-01-01

Low solubility of proteins overexpressed in E. coli is a frequent problem in high-throughput structural genomics. To improve solubility of proteins from mesophilic Shewanella oneidensis MR-1 and thermophilic Clostridium thermocellum JW20, an approach was attempted that included a fusion of the target protein to a maltose-binding protein (MBP) and a decrease of induction temperature. The MBP was selected as the most efficient solubilizing carrier when compared to a glutathione S-transferase and a Nus A protein. A tobacco etch virus (TEV) protease recognition site was introduced between fused proteins using a double polymerase-chain reaction and four primers. In this way, 79 S. oneidensis proteins have been expressed in one case with an N-terminal 30-residue tag and in another case as a fusion protein with MBP. A foreign tag might significantly affect the properties of the target polypeptide. At 37 degrees C and 18 degrees C induction temperatures, only 5 and 17 tagged proteins were soluble, respectively. In fusion with MBP 4, 34, and 38 proteins were soluble upon induction at 37 degrees, 28 degrees, and 18 degrees C, respectively. The MBP is assumed to increase stability and solubility of a target protein by changing both the mechanism and the cooperativity of folding/unfolding. The 66 C. thermocellum proteins were expressed as fusion proteins with MBP. Induction at 37 degrees, 28 degrees, and 18 degrees C produced 34, 57, and 60 soluble proteins, respectively. The higher solubility of C. thermocellum proteins in comparison with the S. oneidensis proteins under similar conditions of induction correlates with the thermophilicity of the host. The two-factor Wilkinson-Harrison statistical model was used to identify soluble and insoluble proteins. Theoretical and experimental data showed good agreement for S. oneidensis proteins; however, the model failed to identify soluble/insoluble Clostridium proteins. A suggestion has been made that the Wilkinson-Harrison model is not applicable to C. thermocellum proteins because it did not account for the peculiarities of protein sequences from thermophiles.

Effect of pH and temperature upon self-assembling process between poly(aspartic acid) and Pluronic F127.

PubMed

Nita, Loredana E; Chiriac, Aurica P; Bercea, Maria

2014-07-01

The present investigation was made in order to evaluate the capability of self-assembling of the two water soluble polymers, respectively, poly(aspartic acid) and Pluronic F127 into well interpenetrated mixture, and to evidence the connection effects intervened during polymer complex formation to exhibit good stability once formed, as well to understand and correlate the binding strength and the interval between better association domains. The effect of pH and temperature on the interpolymeric complex formation between poly(aspartic acid) and Pluronic F127 was studied by combining rheology with light scattering technique. The solution mixtures between poly(aspartic acid) and Pluronic F127 are Newtonian fluids for all ratios among them. Depending on the polymeric mixture composition and experimental temperature, positive or negative deviations of the experimental values from the additive dependence appear. An interesting behavior was registered around 1/1 wt. ratio between the two polymers, when the hydrodynamic diameter of the interpenetrated polymeric particles decreased suddenly. This allows us to conclude the formation of core-shell micelle structure with poly(aspartic acid) core and Pluronic F127 as shell, performed through strong interactions between polymers. This behavior was sustained by the increase of absolute value of zeta potential owing to the decrease of functional groups number at the surface of micelles. Copyright © 2014 Elsevier B.V. All rights reserved.

Enzymatic hydrolysis and fermentation of dilute acid pretreated cornstalk to biohydrogen

NASA Astrophysics Data System (ADS)

Pan, C. M.; Fan, Y. T.; Hou, H. W.

2010-03-01

The coupling method of acid pretreatment and enzymatic hydrolysis of cornstalk for hydrogen production was investigated in this study. Experimental results showed that temperature, pH and enzyme loading all had an individual significant influence on soluble sugar yield and Ps. The optimum condition for soluble sugar was close to that for Ps. The maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS on the optimum enzymatic hydrolysis condition which was 52 °C of temperature, pH4.8 and 9.4 IU/g of enzyme loading.

Strategies to overcome pH-dependent solubility of weakly basic drugs by using different types of alginates.

PubMed

Gutsche, S; Krause, M; Kranz, H

2008-12-01

Weakly basic drugs demonstrate higher solubility at lower pH, thus often leading to faster drug release at lower pH. The objective of this study was to achieve pH-independent release of weakly basic drugs from extended release formulations based on the naturally occurring polymer sodium alginate. Three approaches to overcome the pH-dependent solubility of the weakly basic model drug verapamil hydrochloride were investigated. First, matrix tablets were prepared by direct compression of drug substance with different types of sodium alginate only. Second, pH-modifiers were added to the drug/alginate matrix systems. Third, press-coated tablets consisting of an inner pH-modifier tablet core and an outer drug/sodium alginate coat were prepared. pH-Independent drug release was achieved from matrix tablets consisting of selected alginates and drug substance only. Alginates are better soluble at higher pH. Therefore, they are able to compensate the poor solubility of weakly basic drugs at higher pH as the matrix of the tablets dissolves faster. This approach was successful when using alginates that demonstrated fast hydration and erosion at higher pH. The approach failed for alginates with less-pronounced erosion at higher pH. The addition of fumaric acid to drug/alginate-based matrix systems decreased the microenvironmental pH within the tablets thus increasing the solubility of the weakly basic drug at higher pH. Therefore, pH-independent drug release was achieved irrespective of the type of alginate used. Drug release from press-coated tablets did not provide any further advantages as compound release remained pH-dependent.

Association and dissociation of an aqueous amphiphile at elevated temperatures.

PubMed

Bowron, D T; Finney, J L

2007-08-23

The hydrophobic interaction is often thought to increase with increasing temperature. Although there is good experimental evidence for decreased aqueous solubility and increased clustering of both nonpolar and amphiphilic molecules as temperature is increased, the detailed nature of the changes in intermolecular interactions with temperature remain unknown. By use of isotope substitution neutron scattering difference measurements on a 0.04 mole fraction solution of tert-butanol in water as the solute clustering passes through a temperature maximum, the changes in local intermolecular structures are examined. Although, as expected, the solute molecules cluster through increased contact between their nonpolar head groups with the exclusion of water, the detailed geometry of the mutual interactions changes as temperature increases. As the clustering breaks up with further temperature increase, the local structures formed do not mirror those that were found in the low-temperature dispersed system: the disassembly process is not the reverse of assembly. The clusters formed by the solute head groups are reminiscent of structures that are found in systems of spherical molecules, modulated by the additional constraint of near-maximal hydrogen bonding between the polar tails of the alcohol and the solvent water. Although the overall temperature behavior is qualitatively what would be expected of a hydrophobically driven system, the way the system resolves the competing interactions and their different temperature dependencies is complex, suggesting it could be misleading to think of the aggregation of aqueous amphiphiles solely in terms of a hydrophobic driving force.

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

PubMed

Verberk, Wilco C E P; Bilton, David T; Calosi, Piero; Spicer, John I

2011-08-01

Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to ongoing global climate shifts.

Cocrystal Solubility Product Prediction Using an in combo Model and Simulations to Improve Design of Experiments.

PubMed

Avdeef, Alex

2018-02-02

To predict the aqueous solubility product (K sp ) and the solubility enhancement of cocrystals (CCs), using an approach based on measured drug and coformer intrinsic solubility (S 0 API , S 0 cof ), combined with in silico H-bond descriptors. A regression model was constructed, assuming that the concentration of the uncharged drug (API) can be nearly equated to drug intrinsic solubility (S 0 API ) and that the concentration of the uncharged coformer can be estimated from a linear combination of the log of the coformer intrinsic solubility, S 0 cof , plus in silico H-bond descriptors (Abraham acidities, α, and basicities, β). The optimal model found for n:1 CCs (-log 10 form) is pK sp  = 1.12 n pS 0 API  + 1.07 pS 0 cof  + 1.01 + 0.74 α API ·β cof  - 0.61 β API ; r 2  = 0.95, SD = 0.62, N = 38. In illustrative CC systems with unknown K sp , predicted K sp was used in simulation of speciation-pH profiles. The extent and pH dependence of solubility enhancement due to CC formation were examined. Suggestions to improve assay design were made. The predicted CC K sp can be used to simulate pH-dependent solution characteristics of saturated systems containing CCs, with the aim of ranking the selection of coformers, and of optimizing the design of experiments.

Floating lipid beads for the improvement of bioavailability of poorly soluble basic drugs: in-vitro optimization and in-vivo performance in humans.

PubMed

Abouelatta, Samar M; Aboelwafa, Ahmed A; Khalil, Rawia M; ElGazayerly, Omaima N

2015-01-01

The challenge in developing oral drug delivery systems of poorly soluble basic drugs is primarily due to their pH dependent solubility. Cinnarizine (CNZ), a model for a poorly soluble basic drug, has pH dependent solubility; where it dissolves readily at low pH in the stomach and exhibits a very low solubility at pH values greater than 4. It is also characterized by a short half life of 3-6h, which requires frequent daily administration resulting in poor patient compliance. In an attempt to solve these problems, extended release floating lipid beads were formulated. A 2(4) full factorial design was utilized for optimization of the effects of various independent variables; lipid:drug ratio, % Pluronic F-127, % Sterotex, and Gelucire 43/01:Gelucire 50/13 ratio, on the loading efficiency and release of CNZ from the lipid beads. In-vivo pharmacokinetic study of the optimized CNZ-lipid beads compared to Stugeron® (reference standard) was performed in healthy human volunteers. A promising approach for enhancing the bioavailability of the poorly soluble basic drug, CNZ, utilizing novel and simple floating lipid beads was successfully developed. Zero order release profile of CNZ was achieved for 12h. Mean AUC0-24 and AUC0-∞ of the optimized CNZ-loaded lipid beads were 4.23 and 6.04 times that of Stugeron® tablets respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Solubility and dissolution thermodynamics of phthalic anhydride in organic solvents at 283-313 K

NASA Astrophysics Data System (ADS)

Wang, Long; Zhang, Fang; Gao, Xiaoqiang; Luo, Tingliang; Xu, Li; Liu, Guoji

2017-08-01

The solubility of phthalic anhydride was measured at 283-313 K under atmospheric pressure in ethyl acetate, n-propyl acetate, methyl acetate, acetone, 1,4-dioxane, n-hexane, n-butyl acetate, cyclohexane, and dichloromethane. The solubility of phthalic anhydride in all solvents increased with the increasing temperature. The Van't Hoff equation, modified Apelblat equation, λ h equation, and Wilson model were used to correlate the experimental solubility data. The standard dissolution enthalpy, the standard entropy, and the standard Gibbs energy were evaluated based on the Van't Hoff analysis. The experimental data and model parameters would be useful for optimizing of the separation processes involving phthalic anhydride.

Structure and anomalous solubility for hard spheres in an associating lattice gas model.

PubMed

Szortyka, Marcia M; Girardi, Mauricio; Henriques, Vera B; Barbosa, Marcia C

2012-08-14

In this paper we investigate the solubility of a hard-sphere gas in a solvent modeled as an associating lattice gas. The solution phase diagram for solute at 5% is compared with the phase diagram of the original solute free model. Model properties are investigated both through Monte Carlo simulations and a cluster approximation. The model solubility is computed via simulations and is shown to exhibit a minimum as a function of temperature. The line of minimum solubility (TmS) coincides with the line of maximum density (TMD) for different solvent chemical potentials, in accordance with the literature on continuous realistic models and on the "cavity" picture.

C-106 High-Level Waste Solids: Washing/Leaching and Solubility Versus Temperature Studies

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

GJ Lumetta; DJ Bates; PK Berry

This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing and caustic leaching on the composition of the Hanford tank C-106 high-level waste (HLW) solids. The objective of this work was to determine the composition of the C-106 solids remaining after washing with 0.01M NaOH or leaching with 3M NaOH. Another objective of this test was to determine the solubility of various C-106 components as a function of temperature. The work was conducted according to test plan BNFL-TP-29953-8,Rev. 0, Determination of the Solubility of HLW Sludge Solids. The test went accordingmore » to plan, with only minor deviations from the test plan. The deviations from the test plan are discussed in the experimental section.« less

Drying Characteristics and Water-soluble Polysaccharides Evaluation of Kidney Shape Ganoderma lucidum Drying in Air Circulation System

NASA Astrophysics Data System (ADS)

Prasetyo, D. J.; Jatmiko, T. H.; Poeloengasih, C. D.; Kismurtono, M.

2017-12-01

In this project, drying kinetic of kidney shape Ganoderma lucidum fruiting body in air circulation system was studied. The drying experiments were conducted at 40, 50 and 60°C with air flow rate of 1.3 ms-1. Samples were weighted periodically until no change in sample weight was recorded, and then the samples were analyzed for its moisture content. Four different thin-layer mathematical models (Newton, Page, Two-term, Midilli) were used and compare to evaluate the drying curves of kidney shape G. lucidum. The water-soluble polysaccharides were evaluated in order to find the best drying temperature condition. The results indicates that Midilli model was the fittest model to describe the characteristic of kidney shape G. lucidum in the air circulation drying system and temperature of 50°C was the best drying condition to get highest value of water-soluble polysaccharides.

Removal of Calcium from Scheelite Leaching Solution by Addition of CaSO4 Inoculating Crystals

NASA Astrophysics Data System (ADS)

Liu, Wenting; Li, Yongli; Zeng, Dewen; Li, Jiangtao; Zhao, Zhongwei

2018-04-01

In this work, the solubility behaviors of gypsum and anhydrite in the H2SO4-H3PO4-H2O system were investigated over the temperature range T = 30-80°C, and the results showed that the solubility of anhydrite was considerably lower than that of gypsum. On the basis of the differential solubilities of gypsum and anhydrite, a method was developed to remove calcium from the scheelite leaching solution by adding anhydrite as an inoculating crystal. The effects of the reaction time, concentration of the CaSO4 inoculating crystals, and temperature were investigated. With an addition of CaSO4 inoculating crystals at a concentration of 60 g/L, the Ca2+ concentration of the scheelite leaching solution decreased to a low level of approximately 0.76 g/L after 10 h at 70°C.

Developing a vacuum cooking equipment prototype to produce strawberry jam and optimization of vacuum cooking conditions.

PubMed

Okut, Dilara; Devseren, Esra; Koç, Mehmet; Ocak, Özgül Özdestan; Karataş, Haluk; Kaymak-Ertekin, Figen

2018-01-01

Purpose of this study was to develop prototype cooking equipment that can work at reduced pressure and to evaluate its performance for production of strawberry jam. The effect of vacuum cooking conditions on color soluble solid content, reducing sugars total sugars HMF and sensory properties were investigated. Also, the optimum vacuum cooking conditions for strawberry jam were optimized for Composite Rotatable Design. The optimum cooking temperature and time were determined targeting maximum soluble solid content and sensory attributes (consistency) and minimum Hue value and HMF content. The optimum vacuum cooking conditions determined were 74.4 °C temperature and 19.8 time. The soluble solid content strawberry jam made by vacuum process were similar to those prepared by traditional method. HMF contents of jams produced with vacuum cooking method were well within limit of standards.

Effect of Proteolytic Enzymes and Ginger Extract on Tenderization of M. pectoralis profundus from Holstein Steer.

PubMed

Moon, Sung Sil

2018-02-01

The effects of proteolytic enzymes (bromelain and bromelain+papain) and a ginger extract were assessed on collagen content and solubility, thermal shrinkage temperature of connective tissue, pH, cooking loss, drip loss, and Warner-Bratzler shear force (WBSF) of M. pectoralis profundus isolated from the beef brisket cut. Both proteolytic enzymes and ginger extract led to a significant increase in cooking loss and collagen solubility compared with untreated controls. On the other hand, the peak ( T p ) thermal shrinkage temperature markedly decreased in all treatments compared with those in controls. Samples treated with bromelain, bromelain + papain, and ginger extract showed a significant decrease in WBSF by 36%, 40%, and 37%, respectively, compared with untreated controls. Our findings suggest that ginger extract are useful for postmortem tenderization of meat containing high levels of collagen, compared to control even though, bromelain and bromelain + papain treatments have higher collagen solubility than ginger extract.

Novel Pentablock Copolymers as Thermosensitive Self-Assembling Micelles for Ocular Drug Delivery

PubMed Central

Alami-Milani, Mitra; Zakeri-Milani, Parvin; Valizadeh, Hadi; Salehi, Roya; Salatin, Sara; Naderinia, Ali; Jelvehgari, Mitra

2017-01-01

Many studies have focused on how drugs are formulated in the sol state at room temperature leading to the formation of in situ gel at eye temperature to provide a controlled drug release. Stimuli-responsive block copolymer hydrogels possess several advantages including uncomplicated drug formulation and ease of application, no organic solvent, protective environment for drugs, site-specificity, prolonged and localized drug delivery, lower systemic toxicity, and capability to deliver both hydrophobic and hydrophilic drugs. Self-assembling block copolymers (such as diblock, triblock, and pentablock copolymers) with large solubility variation between hydrophilic and hydrophobic segments are capable of making temperature-dependent micellar assembles, and with further increase in the temperature, of jellifying due to micellar aggregation. In general, molecular weight, hydrophobicity, and block arrangement have a significant effect on polymer crystallinity, micelle size, and in vitro drug release profile. The limitations of creature triblock copolymers as initial burst release can be largely avoided using micelles made of pentablock copolymers. Moreover, formulations based on pentablock copolymers can sustain drug release for a longer time. The present study aims to provide a concise overview of the initial and recent progresses in the design of hydrogel-based ocular drug delivery systems. PMID:28507933

Charging-free electrochemical system for harvesting low-grade thermal energy

PubMed Central

Yang, Yuan; Lee, Seok Woo; Ghasemi, Hadi; Loomis, James; Li, Xiaobo; Kraemer, Daniel; Zheng, Guangyuan; Cui, Yi; Chen, Gang

2014-01-01

Efficient and low-cost systems are needed to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). Thermally regenerative electrochemical cycle (TREC) is an attractive approach which uses the temperature dependence of electrochemical cell voltage to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying temperature, an electrochemical cell is charged at a lower voltage than discharge, converting thermal energy to electricity. Most TREC systems still require external electricity for charging, which complicates system designs and limits their applications. Here, we demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)63−/4− redox pair and solid Prussian blue particles as active materials for the two electrodes. In this system, the spontaneous directions of the full-cell reaction are opposite at low and high temperatures. Therefore, the two electrochemical processes at both low and high temperatures in a cycle are discharge. Heat-to-electricity conversion efficiency of 2.0% can be reached for the TREC operating between 20 and 60 °C. This charging-free TREC system may have potential application for harvesting low-grade heat from the environment, especially in remote areas. PMID:25404325

Effect of polyethylene glycol on the liquid–liquid phase transition in aqueous protein solutions

PubMed Central

Annunziata, Onofrio; Asherie, Neer; Lomakin, Aleksey; Pande, Jayanti; Ogun, Olutayo; Benedek, George B.

2002-01-01

We have studied the effect of polyethylene glycol (PEG) on the liquid–liquid phase separation (LLPS) of aqueous solutions of bovine γD-crystallin (γD), a protein in the eye lens. We observe that the phase separation temperature increases with both PEG concentration and PEG molecular weight. PEG partitioning, which is the difference between the PEG concentration in the two coexisting phases, has been measured experimentally and observed to increase with PEG molecular weight. The measurements of both LLPS temperature and PEG partitioning in the ternary γD-PEG-water systems are used to successfully predict the location of the liquid–liquid phase boundary of the binary γD-water system. We show that our LLPS measurements can be also used to estimate the protein solubility as a function of the concentration of crystallizing agents. Moreover, the slope of the tie-lines and the dependence of LLPS temperature on polymer concentration provide a powerful and sensitive check of the validity of excluded volume models. Finally, we show that the increase of the LLPS temperature with PEG concentration is due to attractive protein–protein interactions. PMID:12391331

Cooling Particle-Coated Bubbles: Destabilization beyond Dissolution Arrest.

PubMed

Poulichet, Vincent; Garbin, Valeria

2015-11-10

Emulsions and foams that remain stable under varying environmental conditions are central in the food, personal care, and other formulated products industries. Foams stabilized by solid particles can provide longer-term stability than surfactant-stabilized foams. This stability is partly ascribed to the observation that solid particles can arrest bubble dissolution, which is driven by the Laplace pressure across the curved gas-liquid interface. We studied experimentally the effect of changes in temperature on the lifetime of particle-coated air microbubbles in water. We found that a decrease in temperature destabilizes particle-coated microbubbles beyond dissolution arrest. A quasi-steady model describing the effect of the change in temperature on mass transfer suggests that the dominant mechanism of destabilization is the increased solubility of the gas in the liquid, leading to a condition of undersaturation. Experiments at constant temperature confirmed that undersaturation alone can drive destabilization of particle-coated bubbles, even for vanishing Laplace pressure. We also found that dissolution of a particle-coated bubble can lead either to buckling of the coating or to gradual expulsion of particles, depending on the particle-to-bubble size ratio, with potential implications for controlled release.

Kinetic bottlenecks to chemical exchange rates for deep-sea animals - Part 1: Oxygen

NASA Astrophysics Data System (ADS)

Hofmann, A. F.; Peltzer, E. T.; Brewer, P. G.

2012-10-01

Ocean warming will reduce dissolved oxygen concentrations which can pose challenges to marine life. Oxygen limits are traditionally reported simply as a static concentration thresholds with no temperature, pressure or flow rate dependency. Here we treat the oceanic oxygen supply potential for heterotrophic consumption as a dynamic molecular exchange problem analogous to familiar gas exchange processes at the sea surface. A combination of the purely physico-chemical oceanic properties temperature, hydrostatic pressure, and oxygen concentration defines the ability of the ocean to supply oxygen to any given animal. This general oceanic oxygen supply potential is modulated by animal specific properties such as the diffusive boundary layer thickness to define and limit maximal oxygen supply rates. Here we combine all these properties into formal, mechanistic equations defining novel oceanic properties that subsume various relevant classical oceanographic parameters to better visualize, map, comprehend, and predict the impact of ocean deoxygenation on aerobic life. By explicitly including temperature and hydrostatic pressure into our quantities, various ocean regions ranging from the cold deep-sea to warm, coastal seas can be compared. We define purely physico-chemical quantities to describe the oceanic oxygen supply potential, but also quantities that contain organism-specific properties which in a most generalized way describe general concepts and dependencies. We apply these novel quantities to example oceanic profiles around the world and find that temperature and pressure dependencies of diffusion and partial pressure create zones of greatest physical constriction on oxygen supply typically at around 1000 m depth, which coincides with oxygen concentration minimum zones. In these zones, which comprise the bulk of the world ocean, ocean warming and deoxygenation have a clear negative effect for aerobic life. In some shallow and warm waters the enhanced diffusion and higher partial pressure due to higher temperatures might slightly overcompensate for oxygen concentration decreases due to decreases in solubility.

Flame Emission Spectrometry in General Chemistry Labs: Solubility Product (K[subscript sp]) of Potassium Hydrogen Phthalate

ERIC Educational Resources Information Center

Nyasulu, Frazier W.; Cusworth, William, III; Lindquist, David; Mackin, John

2007-01-01

In this general chemistry laboratory, flame emission spectrometry is used to determine the potassium ion concentration in saturated solutions of potassium hydrogen phthalate (KHP) in the 0-65 [degree]C temperature range. From these data the solubility products (K[subscript sp]), the Gibbs free energies of solution ([Delta][subscript…

Foliar reflective film and water deficit increase anthocyanin to soluble solids ratio during berry ripening in Merlot

USDA-ARS?s Scientific Manuscript database

Elevated temperature can decrease the ratio of anthocyanins to soluble solids in red-skinned berries and warming trends in grape production regions have raised concern about color to alcohol balance in wines produced from fruit with altered ratios. In this study, we tested the effectiveness of a fol...

Method of immobilizing water-soluble bioorganic compounds on a capillary-porous carrier

DOEpatents

Ershov, Gennady Moiseevich; Timofeev, Eduard Nikolaevich; Ivanov, Igor Borisovich; Florentiev, Vladimir Leonidovich; Mirzabekov, Andrei Darievich

1998-01-01

The method for immobilizing water-soluble bioorganic compounds to capillary-porous carrier comprises application of solutions of water-soluble bioorganic compounds onto a capillary-porous carrier, setting the carrier temperature equal to or below the dew point of the ambient air, keeping the carrier till appearance of water condensate and complete swelling of the carrier, whereupon the carrier surface is coated with a layer of water-immiscible nonluminescent inert oil and is allowed to stand till completion of the chemical reaction of bonding the bioorganic compounds with the carrier.

About the solubility of reduced SWCNT in DMSO

NASA Astrophysics Data System (ADS)

Guan, Jingwen; Martinez-Rubi, Yadienka; Dénommée, Stéphane; Ruth, Dean; Kingston, Christopher T.; Daroszewska, Malgosia; Barnes, Michael; Simard, Benoit

2009-06-01

Single-walled carbon nanotubes (SWCNT) have been reduced with sodium naphthalide in THF. The reduced SWCNT are not only soluble in dimethylsulfoxide (DMSO) to form a stable solution/suspension, but also react spontaneously at room temperature with DMSO to evolve hydrocarbon gases and are converted into functionalized SWCNT. The degree of functionalization is about 2C% and the addends are mainly methyl and small oxygen-containing hydrocarbons. The functionalized SWCNT are apparently more soluble and stable in DMSO solution. It may open a new era for further processing and applications.

Process for crosslinking methylene-containing aromatic polymers with ionizing radiation

NASA Technical Reports Server (NTRS)

Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

1990-01-01

A process for crosslinking aromatic polymers containing radiation-sensitive methylene groups (-CH2-) by exposing the polymers to ionizing radiation thereby causing crosslinking of the polymers through the methylene groups is described. Crosslinked polymers are resistant to most organic solvents such as acetone, alcohols, hydrocarbons, methylene, chloride, chloroform, and other halogenated hydrocarbons, to common fuels and to hydraulic fluids in contrast to readily soluble uncrosslinked polymers. In addition, the degree of crosslinking of the polymers depends upon the percentage of the connecting groups which are methylene which ranges from 5 to 50 pct and preferably from 25 to 50 pct of the connecting groups, and is also controlled by the level of irradiation which ranges from 25 to 1000 Mrads and preferably from 25 to 250 Mrads. The temperature of the reaction conditions ranges from 25 to 200 C and preferably at or slightly above the glass transition temperature of the polymer. The crosslinked polymers are generally more resistant to degradation at elevated temperatures such as greater than 150 C, have a reduced tendency to creep under load, and show no significant embrittlement of parts fabricated from the polymers.

Low-Dimensional Network Formation in Molten Sodium Carbonate

PubMed Central

Wilding, Martin C.; Wilson, Mark; Alderman, Oliver L. G.; Benmore, Chris; Weber, J. K. R.; Parise, John B.; Tamalonis, Anthony; Skinner, Lawrie

2016-01-01

Molten carbonates are highly inviscid liquids characterized by low melting points and high solubility of rare earth elements and volatile molecules. An understanding of the structure and related properties of these intriguing liquids has been limited to date. We report the results of a study of molten sodium carbonate (Na2CO3) which combines high energy X-ray diffraction, containerless techniques and computer simulation to provide insight into the liquid structure. Total structure factors (Fx(Q)) are collected on the laser-heated carbonate spheres suspended in flowing gases of varying composition in an aerodynamic levitation furnace. The respective partial structure factor contributions to Fx(Q) are obtained by performing molecular dynamics simulations treating the carbonate anions as flexible entities. The carbonate liquid structure is found to be heavily temperature-dependent. At low temperatures a low-dimensional carbonate chain network forms, at T = 1100 K for example ~55% of the C atoms form part of a chain. The mean chain lengths decrease as temperature is increased and as the chains become shorter the rotation of the carbonate anions becomes more rapid enhancing the diffusion of Na+ ions. PMID:27080401

Performance of UASB septic tank for treatment of concentrated black water within DESAR concept.

PubMed

Kujawa-Roeleveld, K; Fernandes, T; Wiryawan, Y; Tawfik, A; Visser, M; Zeeman, G

2005-01-01

Separation of wastewater streams produced in households according to their origin, degree of pollution and affinity to a specific treatment constitutes a starting point in the DESAR concept (decentralised sanitation and reuse). Concentrated black water and kitchen waste carry the highest load of organic matter and nutrients from all waste(water)streams generated from different human activities. Anaerobic digestion of concentrated black water is a core technology in the DESAR concept. The applicability of the UASB septic tank for treatment of concentrated black water was investigated under two different temperatures, 15 and 25 degrees C. The removal of total COD was dependent on the operational temperature and attained 61 and 74% respectively. A high removal of the suspended COD of 88 and 94% respectively was measured. Effluent nutrients were mainly in the soluble form. Precipitation of phosphate was observed. Effective sludge/water separation, long HRT and higher operational temperature contributed to a reduction of E. coli. Based on standards there is little risk of contamination with heavy metals when treated effluent is to be applied in agriculture as fertiliser.

Thermal analysis of hydroxypropylmethylcellulose and methylcellulose: powders, gels and matrix tablets.

PubMed

Ford, J L

1999-03-15

This review focuses on the thermal analysis of hydroxypropylmethylcellulose (HPMC) and methylcellulose. Differential scanning calorimetry (DSC) of their powders is used to determine temperatures of moisture loss (in conjunction with thermogravimetric analysis) and glass transition temperatures. However, sample preparation and encapsulation affect the values obtained. The interaction of these cellulose ethers with water is evaluated by DSC. Water is added to the powder directly in DSC pans or preformed gels can be evaluated. Data quality depends on previous thermal history but estimates of the quantity of water bound to the polymers may be made. Water uptake by cellulose ethers may be evaluated by the use of polymeric wafers and by following loss of free water, over a series of timed curves, into wafers in contact with water. Cloud points, which assess the reduction of polymer solubility with increase of temperature, may be assessed spectrophotometrically. DSC and rheometric studies are used to follow thermogelation, a process involving hydrophobic interaction between partly hydrated polymeric chains. The advantages and disadvantages of the various methodologies are highlighted. Copyright.

IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 3. Heavy Lanthanides (Gd–Lu)

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

Mioduski, Tomasz; Gumiński, Cezary, E-mail: cegie@chem.uw.edu.pl; Zeng, Dewen, E-mail: dewen-zeng@hotmail.com

This is the third part of the volume devoted to solubility data for the rare earth metal (REM) fluorides in water and in aqueous ternary and multicomponent systems. It covers experimental results of trivalent fluorides of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu (so-called heavy lanthanides), since no quantitative data on solubilities of TbF{sub 4} and YbF{sub 2} (the most stable compounds at these valencies) are available. The related literature has been covered through the end of 2014. Compilations of all available papers with the solubility data are introduced for each REM fluoride with a corresponding critical evaluation.more » Every such assessment contains a collection of all solubility results in aqueous solution, a selection of suggested solubility data, a solubility equation, and a brief discussion of the multicomponent systems. Only simple fluorides (no complexes or double salts) are treated as the input substances in this report. General features of the systems, such as nature of the equilibrium solid phases, solubility as a function of temperature, influence of ionic strength, solution pH, mixed solvent medium on the solubility, quality of the solubility results, and the solubility as a function of REM atomic number, have already been presented in Part 1 of the volume.« less

pH-Dependent solubility and permeability criteria for provisional biopharmaceutics classification (BCS and BDDCS) in early drug discovery.

PubMed

Varma, Manthena V; Gardner, Iain; Steyn, Stefanus J; Nkansah, Paul; Rotter, Charles J; Whitney-Pickett, Carrie; Zhang, Hui; Di, Li; Cram, Michael; Fenner, Katherine S; El-Kattan, Ayman F

2012-05-07

The Biopharmaceutics Classification System (BCS) is a scientific framework that provides a basis for predicting the oral absorption of drugs. These concepts have been extended in the Biopharmaceutics Drug Disposition Classification System (BDDCS) to explain the potential mechanism of drug clearance and understand the effects of uptake and efflux transporters on absorption, distribution, metabolism, and elimination. The objective of present work is to establish criteria for provisional biopharmaceutics classification using pH-dependent passive permeability and aqueous solubility data generated from high throughput screening methodologies in drug discovery settings. The apparent permeability across monolayers of clonal cell line of Madin-Darby canine kidney cells, selected for low endogenous efflux transporter expression, was measured for a set of 105 drugs, with known BCS and BDDCS class. The permeability at apical pH 6.5 for acidic drugs and at pH 7.4 for nonacidic drugs showed a good correlation with the fraction absorbed in human (Fa). Receiver operating characteristic (ROC) curve analysis was utilized to define the permeability class boundary. At permeability ≥ 5 × 10(-6) cm/s, the accuracy of predicting Fa of ≥ 0.90 was 87%. Also, this cutoff showed more than 80% sensitivity and specificity in predicting the literature permeability classes (BCS), and the metabolism classes (BDDCS). The equilibrium solubility of a subset of 49 drugs was measured in pH 1.2 medium, pH 6.5 phosphate buffer, and in FaSSIF medium (pH 6.5). Although dose was not considered, good concordance of the measured solubility with BCS and BDDCS solubility class was achieved, when solubility at pH 1.2 was used for acidic compounds and FaSSIF solubility was used for basic, neutral, and zwitterionic compounds. Using a cutoff of 200 μg/mL, the data set suggested a 93% sensitivity and 86% specificity in predicting both the BCS and BDDCS solubility classes. In conclusion, this study identified pH-dependent permeability and solubility criteria that can be used to assign provisional biopharmaceutics class at early stage of the drug discovery process. Additionally, such a classification system will enable discovery scientists to assess the potential limiting factors to oral absorption, as well as help predict the drug disposition mechanisms and potential drug-drug interactions.

Hydroxypropyl cellulose stabilizes amorphous solid dispersions of the poorly water soluble drug felodipine.

PubMed

Sarode, Ashish L; Malekar, Swapnil A; Cote, Catherine; Worthen, David R

2014-11-04

Overcoming the low oral bioavailability of many drugs due to their poor aqueous solubility is one of the major challenges in the pharmaceutical industry. The production of amorphous solid dispersions (ASDs) of these drugs using hydrophilic polymers may significantly improve their solubility. However, their storage stability and the stability of their supersaturated solutions in the gastrointestinal tract upon administration are unsolved problems. We have investigated the potential of a low viscosity grade of a cellulosic polymer, hydroxypropyl cellulose (HPC-SSL), and compared it with a commonly used vinyl polymer, polyvinylpyrrolidone vinyl acetate (PVP-VA), for stabilizing the ASDs of a poorly water soluble drug, felodipine. The ASDs were produced using hot melt mixing and stored under standard and accelerated stability conditions. The ASDs were characterized using differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy. Drug dissolution and partitioning rates were evaluated using single- and biphasic dissolution studies. The ASDs displayed superior drug dissolution and partitioning as compared to the pure crystalline drug, which might be attributed to the formation of a drug-polymer molecular dispersion, amorphous conversion of the drug, and drug-polymer hydrogen bonding interactions. Late phase separation and early re-crystallization occurred at lower and higher storage temperatures, respectively, for HPC-SSL ASDs, whereas early phase separation, even at low storage temperatures, was noted for PVP-VA ASDs. Consequently, the partitioning rates for ASDs dispersed in HPC-SSL were greater than those of PVP-VA at lower and room temperature storage, whereas the performance of both of the ASDs was similar when stored at higher temperatures. Copyright © 2014. Published by Elsevier Ltd.

Construction of drug-polymer thermodynamic phase diagrams using Flory-Huggins interaction theory: identifying the relevance of temperature and drug weight fraction to phase separation within solid dispersions.

PubMed

Tian, Yiwei; Booth, Jonathan; Meehan, Elizabeth; Jones, David S; Li, Shu; Andrews, Gavin P

2013-01-07

Amorphous drug-polymer solid dispersions have the potential to enhance the dissolution performance and thus bioavailability of BCS class II drug compounds. The principle drawback of this approach is the limited physical stability of amorphous drug within the dispersion. Accurate determination of the solubility and miscibility of drug in the polymer matrix is the key to the successful design and development of such systems. In this paper, we propose a novel method, based on Flory-Huggins theory, to predict and compare the solubility and miscibility of drug in polymeric systems. The systems chosen for this study are (1) hydroxypropyl methylcellulose acetate succinate HF grade (HPMCAS-HF)-felodipine (FD) and (2) Soluplus (a graft copolymer of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol)-FD. Samples containing different drug compositions were mixed, ball milled, and then analyzed by differential scanning calorimetry (DSC). The value of the drug-polymer interaction parameter χ was calculated from the crystalline drug melting depression data and extrapolated to lower temperatures. The interaction parameter χ was also calculated at 25 °C for both systems using the van Krevelen solubility parameter method. The rank order of interaction parameters of the two systems obtained at this temperature was comparable. Diagrams of drug-polymer temperature-composition and free energy of mixing (ΔG(mix)) were constructed for both systems. The maximum crystalline drug solubility and amorphous drug miscibility may be predicted based on the phase diagrams. Hyper-DSC was used to assess the validity of constructed phase diagrams by annealing solid dispersions at specific drug loadings. Three different samples for each polymer were selected to represent different regions within the phase diagram.

Effects of whey protein concentrate, feed moisture and temperature on the physicochemical characteristics of a rice-based extruded flour.

PubMed

Teba, Carla da Silva; Silva, Erika Madeira Moreira da; Chávez, Davy William Hidalgo; Carvalho, Carlos Wanderlei Piler de; Ascheri, José Luis Ramírez

2017-08-01

The influence of whey protein concentrate (WPC), feed moisture and temperature on the physicochemical properties of rice-based extrudates has been investigated. WPC (0.64-7.36g/100g rice) was extruded under 5 moisture (16.64-23.36g/100g) and 5 temperature (106.36-173.64°C) established by a 3 2 central composite rotational design. Physicochemical properties [color, porosimetry, crystallinity, water solubility and absorption, pasting properties, reconstitution test, proximate composition, amino acids, minerals and electrophoresis] were determined. WPC and feed moisture increased redness, yellowness and decreased luminosity. Feed moisture and temperature increased density and total volume pore. WPC and moisture increased crystallinity, but only WPC increased solubility and decrease the retrogradation tendency. Increasing temperature increased the viscosity of the extrudates. The addition of WPC improved the nutritional composition of the extrudates, especially proteins. It is suggested that the extrusion process positively affected the retention of most of the polypeptides chains. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glass-Transition Temperature of the β-Relaxation as the Major Predictive Parameter for Recrystallization of Neat Amorphous Drugs.

PubMed

Kissi, Eric Ofosu; Grohganz, Holger; Löbmann, Korbinian; Ruggiero, Michael T; Zeitler, J Axel; Rades, Thomas

2018-03-15

Recrystallization of amorphous drugs is currently limiting the simple approach to improve solubility and bioavailability of poorly water-soluble drugs by amorphization of a crystalline form of the drug. In view of this, molecular mobility, α-relaxation and β-relaxation processes with the associated transition temperatures T gα and T gβ , was investigated using dynamic mechanical analysis (DMA). The correlation between the transition temperatures and the onset of recrystallization for nine amorphous drugs, stored under dry conditions at a temperature of 296 K, was determined. From the results obtained, T gα does not correlate with the onset of recrystallization under the experimental storage conditions. However, a clear correlation between T gβ and the onset of recrystallization was observed. It is shown that at storage temperature below T gβ , amorphous nifedipine retains its amorphous form. On the basis of the correlation, an empirical correlation is proposed for predicting the onset of recrystallization for drugs stored at 0% RH and 296 K.

Somatostatin receptor subtype-4 agonist NNC 26-9100 mitigates the effect of soluble Aβ(42) oligomers via a metalloproteinase-dependent mechanism.

PubMed

Sandoval, Karin E; Farr, Susan A; Banks, William A; Crider, Albert M; Morley, John E; Witt, Ken A

2013-07-03

Soluble amyloid-β peptide (Aβ) oligomers have been hypothesized to be primary mediators of Alzheimer's disease progression. In this regard, reduction of soluble Aβ-oligomers levels within the brain may provide a viable means in which to treat the disease. Somatostatin receptor subtype-4 (SSTR4) agonists have been proposed to reduce Aβ levels in the brain via enhancement of enzymatic degradation. Herein we evaluated the effect of selective SSTR4 agonist NNC 26-9100 on the changes in learning and soluble Aβ42 oligomer brain content with and without co-administration of the M13-metalloproteinase family enzyme-inhibitor phosphoramidon, using the senescence-accelerated mouse prone-8 (SAMP8) model. NNC 26-9100 treatment (0.2 µg i.c.v. in 2 µL) improved learning, which was blocked by phosphoramidon (1 and 10mM, respectively). NNC 26-9100 decreased total soluble Aβ42, an effect which was blocked by phosphoramidon (10mM). Extracellular, intracellular, and membrane fractions were then isolated from cortical tissue and assessed for soluble oligomer alterations. NNC 26-9100 decreased the Aβ42 trimeric (12 kDa) form within the extracellular and intracellular fractions, and produced a band-split effect of the Aβ42 hexameric (25 kDa) form within the extracellular fraction. These effects were also blocked by phosphoramdon (1 and 10mM, respectively). Subsequent evaluation of NNC 26-9100 in APPswe Tg2576 transgenic mice showed a similar learning improvement and corresponding reduction in soluble Aβ42 oligomers within extracellular, intracellular, and membrane fractions. These data support the hypothesis that NNC 26-9100 reduces soluble Aβ42 oligomers and enhances learning through a phosphoramidon-sensitive metalloproteinase-dependent mechanism. Copyright © 2013 Elsevier B.V. All rights reserved.

Thermodynamics of dissolved nitrogen, nitrous oxide, and ammonia in perfluorodecalin

NASA Astrophysics Data System (ADS)

Moshnyaga, A. V.; Khoroshilov, A. V.; Selivanova, D. I.; Aksenova, D. M.

2017-11-01

The solubility of N2, N2O, and NH3 is studied in different organic solvents. The best dissolution (0.27 ppm) is found to be for N2O in perfluorodecalin at 291 K and a pressure of 99 kPa. The dependence of N2O solubility in perfluorodecalin on pressure is studied at 291 K. The Gibbs energy of the solubility of nitrogen, nitrous oxide, and ammonia in perfluorodecalin is calculated.

Understanding the Differences Between Cocrystal and Salt Aqueous Solubilities.

PubMed

Cavanagh, Katie L; Maheshwari, Chinmay; Rodríguez-Hornedo, Naír

2018-01-01

This work challenges the popular notion that pharmaceutical salts are more soluble than cocrystals. There are cocrystals that are more soluble than salt forms of a drug and vice-versa. It all depends on the interplay between the chemistry of both the solid and solution phases. Aqueous solubility, pH max , and supersaturation index (SA = S CC /S D or S salt /S D ) of cocrystals and salts of a basic drug, lamotrigine (LTG), were determined, and mathematical models that predict the influence of cocrystal/salt K sp and K a were derived. K sp and SA followed the order LTG-nicotinamide cocrystal (18) > LTG-HCl salt (12) > LTG-saccharin salt (5) > LTG-methylparaben cocrystal (1) > LTG-phenobarbital cocrystal (0.2). The values in parenthesis represent SA under nonionizing conditions. Cocrystal/salt solubility and thermodynamic stability are determined by pH and will drastically change with a single unit change in pH. pH max values ranged from 5.0 (saccharin salt) to 6.4 (methylparaben cocrystal) to 9.0 (phenobarbital cocrystal). Cocrystal/salt pH max dependence on pK sp and pK a shows that cocrystals and salts exhibit different behavior. Solubility and pH max are as important as supersaturation index in assessing the stability and risks associated with conversions of supersaturating forms. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Extended Hansen solubility approach: naphthalene in individual solvents.

PubMed

Martin, A; Wu, P L; Adjei, A; Beerbower, A; Prausnitz, J M

1981-11-01

A multiple regression method using Hansen partial solubility parameters, delta D, delta p, and delta H, was used to reproduce the solubilities of naphthalene in pure polar and nonpolar solvents and to predict its solubility in untested solvents. The method, called the extended Hansen approach, was compared with the extended Hildebrand solubility approach and the universal-functional-group-activity-coefficient (UNIFAC) method. The Hildebrand regular solution theory was also used to calculate naphthalene solubility. Naphthalene, an aromatic molecule having no side chains or functional groups, is "well-behaved', i.e., its solubility in active solvents known to interact with drug molecules is fairly regular. Because of its simplicity, naphthalene is a suitable solute with which to initiate the difficult study of solubility phenomena. The three methods tested (Hildebrand regular solution theory was introduced only for comparison of solubilities in regular solution) yielded similar results, reproducing naphthalene solubilities within approximately 30% of literature values. In some cases, however, the error was considerably greater. The UNIFAC calculation is superior in that it requires only the solute's heat of fusion, the melting point, and a knowledge of chemical structures of solute and solvent. The extended Hansen and extended Hildebrand methods need experimental solubility data on which to carry out regression analysis. The extended Hansen approach was the method of second choice because of its adaptability to solutes and solvents from various classes. Sample calculations are included to illustrate methods of predicting solubilities in untested solvents at various temperatures. The UNIFAC method was successful in this regard.

Characterization of Proteus vulgaris K80 lipase immobilized on amine-terminated magnetic microparticles.

PubMed

Natalia, Agnes; Kristiani, Lidya; Kim, Hyung Kwoun

2014-10-01

Proteus vulgaris K80 lipase was expressed in Escherichia coli BL21 (DE3) cells and immobilized on amine-terminated magnetic microparticles (Mag-MPs). The immobilization yield and activity retention were 84.15% and 7.87%, respectively. A homology model of lipase K80 was constructed using P. mirabilis lipase as the template. Many lysine residues were located on the protein surface, remote from active sites. The biochemical characteristics of immobilized lipase K80 were compared with the soluble free form of lipase K80. The optimum temperature of K80-Mag-MPs was 60°C, which was 20°C higher than that of the soluble form. K80-Mag-MPs also tended to be more stable than the soluble form at elevated temperatures and a broad range of pH. K80-Mag-MP maintained its stable form at up to 40°C and in a pH range of 5.0- 10.0, whereas soluble K80 maintained its activity up to 35°C and pH 6.0-10.0. K80-Mag-MPs had broader substrate specificity compared with that of soluble K80. K80-Mag-MPs showed about 80% residual relative activity after five recovery trials. These results indicate the potential benefit of K80-Mag-MPs as a biocatalyst in various industries.

Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties

NASA Astrophysics Data System (ADS)

Kang, Jongeun; Lee, Hyunseung; Kim, Young-Nam; Yeom, Areum; Jeong, Heejeong; Lim, Yong Taik; Hong, Kwan Soo

2013-09-01

Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe2O4 MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T2 relaxivities ( r 2) at 4.7 T and room temperature in the range of 60 to 300 mM-1s-1, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe2O4 MNPs could be used as initial base cores of MRI T2 CAs, with almost unique T2 relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis.

Selective retardation of perfume oil evaporation from oil-in-water emulsions stabilized by either surfactant or nanoparticles.

PubMed

Binks, Bernard P; Fletcher, Paul D I; Holt, Benjamin L; Beaussoubre, Pascal; Wong, Kenneth

2010-12-07

We have used dynamic headspace analysis to investigate the evaporation rates of perfume oils from stirred oil-in-water emulsions into a flowing gas stream. We compare the behavior of an oil of low water solubility (limonene) and one of high water solubility (benzyl acetate). It is shown how the evaporation of an oil of low water solubility is selectively retarded and how the retardation effect depends on the oil volume fraction in the emulsion. We compare how the evaporation retardation depends on the nature of the adsorbed film stabilizing the emulsion. Surfactant films are less effective than adsorbed films of nanoparticles, and the retardation can be further enhanced by compression of the adsorbed nanoparticle films by preshrinking the emulsion drops.

Chemical and spectroscopic analyses of organic matter transformation in warming tundra soils

NASA Astrophysics Data System (ADS)

Herndon, E.; Roy Chowdhury, T.; Mann, B. F.; Graham, D. E.; Bargar, J.; Gu, B.; Liang, L.

2013-12-01

Many tundra soils are currently major carbon sinks; however, an increase in temperature may shift these systems to C sources and create a positive feedback for warming. In order to predict future C release from tundra soils, it is necessary to quantify rates of SOM degradation and to identify the reactants and products of microbial decomposition reactions. In this study, multiple spectroscopic techniques are used to investigate SOM during laboratory incubations of tundra soils. We aim to characterize the chemical transformation of organic matter during decomposition as a function of temperature and geochemistry. Frozen soil cores were obtained from the Barrow Environmental Observatory (BEO) in northern Alaska as part of the Next Generation Ecosystem Experiment Arctic project. To investigate the influence of temperature on organic matter degradation and compositional changes, soil horizons from each core were homogenized and soil material was incubated at -2°C, +4°C, or +8°C. Samples were sacrificed periodically over 100 days, and chemical and physical extractions were used to separate SOM into operationally-defined pools, including light (density < 1.6 g cm-2) and mineral-bound, and water-, acid-, base-, and non-soluble fractions. A suite of wet-chemical and spectroscopic analyses was used to measure CO2 and CH4 formation and soil C compositional changes, including techniques such as Fourier transform infrared spectroscopy, high performance liquid chromatography (HPLC), high resolution mass spectrometry, and X-ray absorption spectroscopy. Detailed chemical and spectroscopic analyses reveal significant differences amongst extracts and with depth in the soil. In general, more organic C was extracted in the base than in the acid and water fractions, and mineral-bound organic C increased with depth. The water-soluble C fraction showed the lowest molar absorptivity of the three extracts and consisted of mostly lower-molecular weight organics. Acid-soluble C increased with increasing mineral content of the soil, likely due to the presence of labile organics bound to Fe-oxide minerals. In addition, 13-80% of the total C remained in soil following sequential chemical extractions, suggesting resistance to degradation and strong association with minerals. Soil incubations showed temperature-dependent production of CO2 and CH4, indicating microbial C degradation. The masses of CO2 and CH4 released represent only a small fraction of the total soil organic C, and little change in was observed in bulk SOM. However, the water-soluble C exhibited significant vulnerability to degradation, as revealed by HPLC and spectroscopic analyses, and these results suggest potential pathways for chemical transformation of soil C during decomposition. The results of this study will contribute to a computational modeling framework for understanding sources and rates of C fluxes from soils to the atmosphere and will help elucidate potential changes to Arctic tundra systems subject to warming.

Biphasic catalysis in water/carbon dioxide micellar systems

DOEpatents

Jacobson, Gunilla B.; Tumas, William; Johnston, Keith P.

2002-01-01

A process is provided for catalyzing an organic reaction to form a reaction product by placing reactants and a catalyst for the organic reaction, the catalyst of a metal complex and at least one ligand soluble within one of the phases of said aqueous biphasic system, within an aqueous biphasic system including a water phase, a dense phase fluid, and a surfactant adapted for forming an emulsion or microemulsion within the aqueous biphasic system, the reactants soluble within one of the phases of the aqueous biphasic system and convertible in the presence of the catalyst to a product having low solubility in the phase in which the catalyst is soluble; and, maintaining the aqueous biphasic system under pressures, at temperatures, and for a period of time sufficient for the organic reaction to occur and form the reaction product and to maintain sufficient density on the dense phase fluid, the reaction product characterized as having low solubility in the phase in which the catalyst is soluble.

Diffusion and solubility coefficients determined by permeation and immersion experiments for organic solvents in HDPE geomembrane.

PubMed

Chao, Keh-Ping; Wang, Ping; Wang, Ya-Ting

2007-04-02

The chemical resistance of eight organic solvents in high density polyethylene (HDPE) geomembrane has been investigated using the ASTM F739 permeation method and the immersion test at different temperatures. The diffusion of the experimental organic solvents in HDPE geomembrane was non-Fickian kinetic, and the solubility coefficients can be consistent with the solubility parameter theory. The diffusion coefficients and solubility coefficients determined by the ASTM F739 method were significantly correlated to the immersion tests (p<0.001). The steady state permeation rates also showed a good agreement between ASTM F739 and immersion experiments (r(2)=0.973, p<0.001). Using a one-dimensional diffusion equation based on Fick's second law, the diffusion and solubility coefficients obtained by immersion test resulted in over estimates of the ASTM F739 permeation results. The modeling results indicated that the diffusion and solubility coefficients should be obtained using ASTM F739 method which closely simulates the practical application of HDPE as barriers in the field.

RNA interference of Arabidopsis beta-amylase8 prevents maltose accumulation upon cold shock and increases sensitivity of PSII photochemical efficiency to freezing stress.

PubMed

Kaplan, Fatma; Guy, Charles L

2005-12-01

It has been suggested that beta-amylase (BMY) induction during temperature stress in Arabidopsis could lead to starch-dependent maltose accumulation, and that maltose may contribute to protection of the electron transport chain and proteins in the chloroplast stroma during acute stress. A time-course transcript profiling analysis for cold shock at 4 degrees C revealed that BMY8 (At4g17090) was induced specifically in response to cold shock, while major induction was not observed for any of the other eight beta-amylases. A parallel metabolite-profiling analysis revealed a robust transient maltose accumulation during cold shock. BMY8 RNAi lines with lower BMY8 expression exhibited a starch-excess phenotype, and a dramatic decrease in maltose accumulation during a 6-h cold shock at 4 degrees C. The decreased maltose content was also accompanied by decreased glucose, fructose and sucrose content in the BMY8 RNAi plants, consistent with the roles of beta-amylase and maltose in transitory starch metabolism. BMY8 RNAi lines with reduced soluble sugar content exhibited diminished chlorophyll fluorescence as F(v)/F(m) ratio compared with wild type, suggesting that PSII photochemical efficiency was more sensitive to freezing stress. Together, carbohydrate analysis and freezing stress results of BMY8 RNAi lines indicate that increased maltose content, by itself or together through a maltose-dependent increase in other soluble sugars, contributes to the protection of the photosynthetic electron transport chain during freezing stress.

Carbollide solubility and chemical compatibility summary

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

McCabe, D.J.

1993-08-17

This report examines the value of the cobalt dicarbollide anion as an effective form of in-tank precipitation. The cobalt dicarbollide anion (CDC) has been investigated for the possible replacement of tetraphenyl borate anion (TPB) for precipitation of cesium in SRS High Level Waste (HLW). The solubility of the cesium CDC in 5 M salt solutions and the reactivity with caustic have been studied extensively. The solubility of CSCDC in a mixture of 4 M sodium nitrate and 1 m sodium hydroxide is {approximately}2 {times} 10{sup {minus}3} M at 40{degrees}C. Furthermore, the CDC decomposes in 1 M sodium hydroxide solution withmore » apparent first order kinetics with a half-life of 7.3 days at 60 {degrees}C and 94 days at 40{degrees}C. Tank temperatures are currently estimated to approach 60{degrees}C during the ITP filtration cycle. This solubility and rapid decomposition of the CDC under highly alkaline conditions and high temperature would require increasing the quantity of CDC and nonradioactive cesium which must be added, increasing the cost of production. Increasing the quantity of CDC would necessitate recovery of the material, probably using a solvent extraction system. Due to the large amount of nonradioactive cesium which must be added, the total amount of precipitate formed exceeds that for TPB precipitation. Also, formation of sodium and/or potassium precipitates compete with cesium salt precipitation in 5 M salt solutions at lower temperature (<30{degrees}C). Decomposition generates hydrogen, which may lead to process complications.« less

Computing gas solubility in reservoir waters for environmental chemistry applications: the role of satellite observations

NASA Astrophysics Data System (ADS)

Rosa, R.; Lima, I.; Ramos, F.; Bambace, L.; Assireu, A.; Stech, J.; Novo, E.; Lorenzeti, L.

Atmospheric greenhouse gases concentration has increased during the past centuries basically due to biogenic and pyrogenic anthopogenic emissions Recent investigations have shown that gas emission methane as an important example from tropical hydroelectric reservoirs may comprise a considerable fraction of the total anthropogenic bulk In order to evaluate the concentration of gases of potential importance in environmental chemistry the solubility of such gases have been collected and converted into a uniform format using the Henry s law which states that the solubility of a gas in a liquid is directly proportional to its partial pressure However the Henry s law can be derived as a function of temperature density molar mixing ratio in the aqueous phase and molar mass of water In this paper we show that due to the complex temperature variation and water composition measured in brazilian tropical reservoirs as Serra da Mesa and Manso expressive secular variation on the traditional solubility constants concentration of a species in the aqueous phase by the partial pressure of that species in the gas phase can change in a rate of approximately 30 in 6 decades This estimation comes from a computational analysis of temperature variation measured during 6 months in Serra da Mesa and Manso reservoirs taking into account a simulated density and molar mass variation of the aqueous composition in these environments As an important global change issue from this preliminary analysis we discuss its role in the current estimations on the concentration emission rates

Effect of digestion temperature and pH on treatment efficiency and evolution of volatile fatty acids during thermophilic aerobic digestion of model high strength agricultural waste.

PubMed

Ugwuanyi, J Obeta; Harvey, L M; McNeil, B

2005-04-01

Thermophilic aerobic digestion (TAD) of a model agricultural waste, potato peel slurry, at soluble chemical oxygen demand (COD) load equivalent to approximately 8.0 gl(-1), was carried out under batch conditions at 0.5 vvm aeration rate. Digestions were carried out at temperatures of 45, 50, 55, 60 and 65 degrees C (or left unregulated) without pH control to study the effect of digestion temperatures on TAD. The effects of digestion pH on the process were studied at pH 6.0, 7.0, 8.0, 9.0 and 9.5 (and in unregulated control) all at 55 degrees C. Except for digestion at 65 degrees C, which was inoculated extraneously using culture of Bacillus strearothermophilus all reactions were carried out using the populations indigenous to the waste. During digestion at different temperatures, the removal of soluble COD increased with temperature to reach a peak at 60 degrees C before declining slightly, removal of soluble solid (SS) followed similar pattern and reached peak at 65 degrees C being the highest temperature studied, while the degradation of TSS and TS (TSS + TS) decreased with an increase in temperature. Digestion at pH 7.0 was more efficient than at other pH values. Acetate was the predominant volatile fatty acid (VFA) in all the reactions and accounted for up to 90% of the total. Digestion at 60 degrees C led to the greatest accumulation of acetate, and this coincided with the period of highest oxygen uptake, and rapid consumption of soluble carbohydrate. Iso-valerate was also produced at all pH values. Digestion at 55 degrees C and also at pH 7.0 led to rapid and efficient processes with least accumulation of VFA and should be of interest in full-scale processes whenever it is practicable to regulate the digestion pH and temperature. The result of digestion at unregulated pH indicates that gradual adaptation may be used to achieve efficient treatment at elevated pH values. This would be of interest in full-scale processes where it is not practicable to tightly regulate digestion pH, and where the waste is produced at a pH value much higher than neutral.

Aerospace Structural Materials Handbook Supplement GRCop-84

NASA Technical Reports Server (NTRS)

Ellis, David L.; Gray, Hugh R. (Technical Monitor); Nathel, Michael (Technical Monitor)

2001-01-01

GRCop-84 is a high strength-high conductivity copper-based alloy developed at NASA Glenn Research Center for combustion chamber liners of regeneratively cooled rocket engines. It also has promise for other high heat flux applications operating at temperatures up to 700 C (1292 F) and potentially higher. The alloy must be made by powder metallurgy techniques such as gas atomization. Slower cooling rates such as those experienced during casting do not develop a proper microstructure. Once made into powder, the alloy exhibits excellent processability using conventional consolidation and forming techniques, e.g., extrusion and rolling. GRCop-84 is strengthened by a combination of dispersion and precipitation strengthening by fine (50-500 nanometer (2-20 microinch)) Cr2Nb particles and Hall-Petch strengthening from a fine copper grain size. The presence of a high volume fraction of particles prevents grain boundary sliding at high temperatures and contributes to the alloy's overall good high temperature mechanical properties. Maximum thermal conductivity is obtained by using two alloying elements (Cr, Nb) with limited solubility in solid Cu that form a high temperature intermetallic compound with an even lower solid solubility. The resulting matrix of the alloy is nearly pure copper. The limited solubility also minimizes Cr2Nb particle coarsening at elevated temperatures and enhances microstructural and mechanical property stability. Further enhancement of the microstructural stability is obtained by using a high volume fraction (approx. 14 vol.%) of Cr2Nb particles that effectively pin grain growth.

Metal/silicate partitioning of Pt and the origin of the "late veneer"

NASA Astrophysics Data System (ADS)

Ertel, W.; Walter, M. J.; Drake, M. J.; Sylvester, P. J.

2002-12-01

Highly siderophile elements (HSEs) are perfect tools for investigating core forming processes in planetary bodies due to their Fe-loving (siderophile) geochemical behavior. Tremendous scientific effort was invested into this field during the past 10 years - mostly in 1 atm experiments. However, little is known about their high-pressure geochemistry and partitioning behavior between core and mantle forming phases. This knowledge is essential to distinguish between equilibrium (Magma Ocean) and non-equilibrium (heterogeneous accretion, late veneer) models for the accretion history for the early Earth. We therefore chose to investigate the partitioning behavior of Pt up to pressures of 140 kbar (14 GPa) and temperatures of 1950°C. The used melt composition - identical to melt systems used in 1 atm experiments - is the eutectic composition of Anorthite-Diopside (AnDi), a pseudo-basalt. A series of runs were performed which were internaly buffered by the piston cylinder apparatus, and were followed by duplicate experiments buffered in the AnDi-C-CO2 system. These experiments constitute reversals since they approach equilibrium from an initially higher and lower Pt solubility (8 ppm in the non-buffered runs, and essentially Pt free in the buffered runs). Experimental charges were encapsulated in Pt capsules which served as source for Pt. Experiments up to 20 kbar were performed in a Quickpress piston cylinder apparatus, while experiments at higher pressures were performed in a Walker-type (Tucson, AZ) and a Kawai-type (Misasa, Japan) multi anvil apparatus. Time series experiments were performed in piston-cylinder runs to determine minimum run durations for the achievement of equilibrium, and to guarantee high-quality partitioning data. 6 hours was found to be sufficient to obtain equilibrium. In practice, all experiments exceeded 12 hours to assure equilibrium. In a second set of runs the temperature dependence of the partitioning behavior of Pt was investigated between the melting point of the 1 atm, AnDi system and the melting point of the Pt capsule material. Over 150 piston cylinder and 12 multi anvil experiments have been performed. Pt solubility is only slightly dependent on temperature, decreasing between 1800 and 1400°C by less than an order of magnitude. In consequence, the partitioning behavior of Pt is mostly determined by its oxygen fugacity dependence, which has only been determined in 1 atm experiments. At 10 kbar, metal/silicate partition coefficients (D's) decrease by about 3 orders of magnitude. The reason for this is not understood, but might be attributed to a first order phase transition as found for, e.g., SiO2 or H2O. Above 10 kbar any increase in pressure does not lead to any further significant decrease in partition coefficients. Solubilities stay roughly constant up to 140 kbar. Abundances of moderately siderophile elements were possibly established by metal/silicate equilibrium in a magma ocean. These results for Pt suggest that the abundances of HSEs were most probably established by the accretion of a chondritic veneer following core formation, as metal/silicate partition coefficients are too high to be consistent with metal/silicate equilibrium in a magma ocean.

Predicting the solubility of gases in Nitrile Butadiene Rubber in extreme conditions using molecular simulation

NASA Astrophysics Data System (ADS)

Khawaja, Musab; Molinari, Nicola; Sutton, Adrian; Mostofi, Arash

In the oil and gas industry, elastomer seals play an important role in protecting sensitive monitoring equipment from contamination by gases - a problem that is exacerbated by the high pressures and temperatures found down-hole. The ability to predict and prevent such permeative failure has proved elusive to-date. Nitrile butadiene rubber (NBR) is a common choice of elastomer for seals due to its resistance to heat and fuels. In the conditions found in the well it readily absorbs small molecular weight gases. How this behaviour changes quantitatively for different gases as a function of temperature and pressure is not well-understood. In this work a series of fully atomistic simulations are performed to understand the effect of extreme conditions on gas solubility in NBR. Widom particle insertion is used to compute solubilities. The importance of sampling and allowing structural relaxation upon compression are highlighted, and qualitatively reasonable trends reproduced. Finally, while at STP it has previously been shown that the solubility of CO2 is higher than that of He in NBR, we observe that under the right circumstances it is possible to reverse this trend.

[Evaluation of inverse gas chromatography (IGC) methods to measure astragaloside solubility parameter from Buyang Huanwu decoction].

PubMed

Tang, Yu; Hu, Chao; Liao, Qiong; Liu, Wen-long; Yang, Yan-tao; He, Hong; He, Fu-yuan

2015-01-01

The solubility parameter determination of astrageloside from Buyang Huanwu decoction with inverse gas chromatography (IGC) method evaluation was investigated in this paper. Di-n-octyl phthalate Kwai alternative sample was used to carry out methodological study. The accuracy of the measured correlation coefficient was 0.992 1. Experimental precision measured by IGC experiments showed that the results were accurate and reliable. The sample was uniformly coated on the surface of an inert carrier and N2 gas was carrier gas, a variety of polar solvents such as isopropanol, toluene, acetone, chloroform, cyclohexane as probes. TCD detector temperature was 150 degrees C, gas room temperature was 120 degrees C. Similar headspace method was used whichever over 1 μL gas into the GC measurement, Retention time t(R), t(0) and all the parameters of air and probes molecules within the column were tested. Astragaloside solubility parameter was (21.02 ± 2.4) [J x cm(-3)] ½, literature value was 19.24 [J x cm(-3)] ½, and relevant coefficient was 0.984 5. IGC method is effective and accurate to measure ingredients solubility parameter.

Sources of Water-soluble Organic Aerosol in the Southeastern United States - Evidence of SOA Formed Through Heterogeneous Reactions

NASA Astrophysics Data System (ADS)

Zhang, X.; Weber, R. J.

2010-12-01

Recent laboratory studies suggest partitioning of semi-volatile organic compounds (SVOCs) to liquid water followed by heterogeneous chemical transformation as a possible route to forming secondary organic aerosol (SOA). This paper will present results from observational studies of SOA formation using Water-Soluble Organic Carbon (WSOC) fraction of SOA, soluble brown carbon (e.g., light absorption spectra), organic acids and a number of aerosol source tracers in the Southeastern U.S., a region known for extensive biogenic and anthropogenic VOC emissions. Based on 24-h integrated filter measurements at 15 sites in the southeast throughout the year of 2007, a PMF analysis identified a factor characterized by the co-abundance of WSOC (58 percent of the total), oxalate (51 percent) and brown carbon (Abs365) (44 percent), which is consistent with the aqueous phase SOA formation mechanism in which water-soluble organic products from gas-phase photochemistry dissolve in liquid (fog/cloud droplets or particle water) and react further to form oligomers, light absorbing compounds, and light-weight organic acids, with oxalic acid being the most abundant one [Hecobian et al., 2010; Zhang et al., 2010]. The temporal variability of this factor correlated well with ambient temperature, possibly owing to the large impact from biogenic emissions, which are dependent on temperature and known to be significant over the southeast. PMF analysis of other data sets collected in Atlanta with online instruments during summer support these findings; as do other studies based on different data sets and data-analysis methods [Hennigan et al., 2008a; Hennigan et al., 2008b; Hennigan et al., 2008c; Hennigan et al., 2009]. Overall, we find that WSOC is largely secondary (roughly 75 to 85 percent) and estimate that 65 to 75 percent of the secondary WSOC formed in the southeast involves some form of aqueous phase chemical process. Hecobian, A., X. Zhang, M. Zheng, N. Frank, E. S. Edgerton, and R. J. Weber (2010), Water-soluble organic aerosol material and the light-absorption characteristics of aqueous extracts measured over the southeastern United States, Atm. Chem. Phys., 10, 5965-5977. Hennigan, C. J., M. H. Bergin, J. E. Dibb, and R. J. Weber (2008a), Enhanced secondary organic aerosol formation due to water uptake by fine particles, Geophys. Res. Lett., 35, L18801, 18810.11029/12008GL035046. Hennigan, C. J., M. H. Bergin, and R. J. Weber (2008b), Correlations between water-soluble organic aerosol and water vapor: A synergistic effect from biogenic emissions?, Environ. Sci. Tech., 42(24), 9079-9085. Hennigan, C. J., et al. (2008c), On the volatility and production mechanisms of newly formed nitrate and water soluble organic aerosol in Mexico City, Atm. Chem. Phys., 8, 3761-3768. Hennigan, C. J., M. H. Bergin, A. G. Russell, A. Nenes, and R. J. Weber (2009), Gas/particle partitioning of water-soluble organic aerosol in Atlanta, Atm. Chem. Phys., 9, 3613-3628. Zhang, X., A. Hecobian, M. Zheng, N. Frank, and R. J. Weber (2010), Biomass buring impact on PM2.5 over the southeastern U.S.: Intgrating chemically speciated FRM filter measurements, MODIS fire counts and PMF analysis, Atm. Chem. Phys., 10, 6839-6853.

Prediction of pH dependent absorption using in vitro, in silico, and in vivo rat models: Early liability assessment during lead optimization.

PubMed

Saxena, Ajay; Shah, Devang; Padmanabhan, Shweta; Gautam, Shashyendra Singh; Chowan, Gajendra Singh; Mandlekar, Sandhya; Desikan, Sridhar

2015-08-30

Weakly basic compounds which have pH dependent solubility are liable to exhibit pH dependent absorption. In some cases, a subtle change in gastric pH can significantly modulate the plasma concentration of the drug and can lead to sub-therapeutic exposure of the drug. Evaluating the risk of pH dependent absorption and potential drug-drug interaction with pH modulators are important aspects of drug discovery and development. In order to assess the risk around the extent of decrease in the systemic exposure of drugs co-administered with pH modulators in the clinic, a pH effect study is carried out, typically in higher species, mostly dog. The major limitation of a higher species pH effect study is the resource and material requirement to assess this risk. Hence, these studies are mostly restricted to promising or advanced leads. In our current work, we have used in vitro aqueous solubility, in silico simulations using GastroPlus™ and an in vivo rat pH effect model to provide a qualitative assessment of the pH dependent absorption liability. Here, we evaluate ketoconazole and atazanavir with different pH dependent solubility profiles and based on in vitro, in silico and in vivo results, a different extent of gastric pH effect on absorption is predicted. The prediction is in alignment with higher species and human pH effect study results. This in vitro, in silico and in vivo (IVISIV) correlation is then extended to assess pH absorption mitigation strategy. The IVISIV predicts pH dependent absorption for BMS-582949 whereas its solubility enhancing prodrug, BMS-751324 is predicted to mitigate this liability. Overall, the material requirement for this assessment is substantially low which makes this approach more practical to screen multiple compounds during lead optimization. Copyright © 2015 Elsevier B.V. All rights reserved.

Impedance spectroscopy of water soluble resin modified by zirconium sulphate

NASA Astrophysics Data System (ADS)

Joseph, Anandraj; Joshi, Girish M.

2018-04-01

We successfully modified water soluble resin polyvinyl alcohol (PVA) by loading zirconium sulphate (ZrSO4). We demonstrated the measurement of electrical properties by using impedance analyser across frequency range (10 Hz-1 MHz) and the temperature range of (30°C to 150°C). The impedance spectroscopy demonstrates decrease in bulk resistance as a function of temperature loading of zirconia 2.5 wt. %. Increase in AC (10-5 S/cm and DC conductivity (10- 2 S/m) observed due to ionic contribution of zirconia. However, the electrical properties of PVA/ZrSO4 composite useful to develop battery electrolyte applications.

Soluble Proteins Form Film by the Treatment of Low Temperature Plasma

NASA Astrophysics Data System (ADS)

Ikehara, Sanae; Sakakita, Hajime; Ishikawa, Kenji; Akimoto, Yoshihiro; Nakanishi, Hayao; Shimizu, Nobuyuki; Hori, Masaru; Ikehara, Yuzuru

2015-09-01

It has been pointed out that low temperature plasma in atmosphere was feasible to use for hemostasis without heat injury. Indeed, earlier studies demonstrated that low temperature plasma played an important role to stimulate platelets to aggregate and turned on the proteolytic activities of coagulation factors, resulting in the acceleration of the natural blood coagulation process. On the other hands, our developed equips could immediately form clots upon the contact with plasma flair, while the histological appearance was different from natural coagulation. Based on these findings in formed clots, we sought to determine if plasma flair supplied by our devices was capable of forming film using a series of soluble proteins Following plasma treatment, films were formed from bovine serum albumin, and the other plasma proteins at physiological concentration. Analysis of trans-electron microscope demonstrated that plasma treatment generated small protein particles and made them fuse to be larger aggregations The combined results demonstrated that plasma are capable of aggregating soluble proteins and that platelets and coagulation factors are not necessary for plasma induced blood coagulation. Supported in part by Grants-in-Aid for Scientific Research on Priority Area (21590454, 24590498, and 24108006 to Y. I.).

Solubilization, Solution Equilibria, and Biodegradation of PAH's under Thermophilic Conditions

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

Viamajala, S.; Peyton, B. M.; Richards, L. A.

Biodegradation rates of PAHs are typically low at mesophilic conditions and it is believed that the kinetics of degradation is controlled by PAH solubility and mass transfer rates. Solubility tests were performed on phenanthrene, fluorene and fluoranthene at 20 C, 40 C and 60 C and, as expected, a significant increase in the equilibrium solubility concentration and of the rate of dissolution of these polycyclic aromatic hydrocarbons (PAHs) was observed with increasing temperature. A first-order model was used to describe the PAH dissolution kinetics and the thermodynamic property changes associated with the dissolution process (enthalpy, entropy and Gibb's free energymore » of solution) were evaluated. Further, other relevant thermodynamic properties for these PAHs, including the activity coefficients at infinite dilution, Henry's law constants and octanol-water partition coefficients, were calculated in the temperature range 20-60 C. In parallel with the dissolution studies, three thermophilic Geobacilli were isolated from compost that grew on phenanthrene at 60 C and degraded the PAH more rapidly than other reported mesophiles. Our results show that while solubilization rates of PAHs are significantly enhanced at elevated temperatures, the biodegradation of PAHs under thermophilic conditions is likely mass transfer limited due to enhanced degradation rates.« less

Effects of chitosan inhibitor on the electrochemical corrosion behavior of 2205 duplex stainless steel

NASA Astrophysics Data System (ADS)

Yang, Se-fei; Wen, Ying; Yi, Pan; Xiao, Kui; Dong, Chao-fang

2017-11-01

The effects of chitosan inhibitor on the corrosion behavior of 2205 duplex stainless steel were studied by electrochemical measurements, immersion tests, and stereology microscopy. The influences of immersion time, temperature, and chitosan concentration on the corrosion inhibition performance of chitosan were investigated. The optimum parameters of water-soluble chitosan on the corrosion inhibition performance of 2205 duplex stainless steel were also determined. The water-soluble chitosan showed excellent corrosion inhibition performance on the 2205 duplex stainless steel. Polarization curves demonstrated that chitosan acted as a mixed-type inhibitor. When the stainless steel specimen was immersed in the 0.2 g/L chitosan solution for 4 h, a dense and uniform adsorption film covered the sample surface and the inhibition efficiency (IE) reached its maximum value. Moreover, temperature was found to strongly influence the corrosion inhibition of chitosan; the inhibition efficiency gradually decreased with increasing temperature. The 2205 duplex stainless steel specimen immersed in 0.4 g/L water-soluble chitosan at 30°C displayed the best corrosion inhibition among the investigated specimens. Moreover, chitosan decreased the corrosion rate of the 2205 duplex stainless steel in an FeCl3 solution.