Direct Assembly of Modified Proteins on Carbon Nanotubes in an Aqueous Solution

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol; Harrison, Joycelyn S.

2007-01-01

Carbon nanotubes (CNTs) have superior mechanical and electrical properties that have opened up many potential applications. However, poor dispersibility and solubility, due to the substantial van der Waals attraction between tubes, have prevented the use of CNTs in practical applications, especially biotechnology applications. Effective dispersion of CNTs into small bundles or individual tubes in solvents is crucial to ensure homogeneous properties and enable practical applications. In addition to dispersion of CNTs into a solvent, the selection of appropriate solvent, which is compatible with a desired matrix, is an important factor to improve the mechanical, thermal, optical, and electrical properties of CNT-based fibers and composites. In particular, dispersion of CNTs into an aqueous system has been a challenge due to the hydrophobic nature of CNTs. Here we show an effective method for dispersion of both single wall CNTs (SWCNTs) and few wall CNTs (FWCNTs) in an aqueous buffer solution. We also show an assembly of cationized Pt-cored ferritins on the well dispersed CNTs in an aqueous buffer solution.

Development of a Singlet Oxygen Absorption Capacity (SOAC) Assay Method. Measurements of the SOAC Values for Carotenoids and α-Tocopherol in an Aqueous Triton X-100 Micellar Solution.

PubMed

Mukai, Kazuo; Ouchi, Aya; Azuma, Nagao; Takahashi, Shingo; Aizawa, Koichi; Nagaoka, Shin-Ichi

2017-02-01

Recently, a new assay method for the quantification of the singlet oxygen absorption capacity (SOAC) of antioxidants (AOs) and food extracts in homogeneous organic solvents was proposed. In this study, second-order rate constants (k Q ) for the reaction of singlet oxygen ( 1 O 2 ) with eight different carotenoids (Cars) and α-tocopherol (α-Toc) were measured in an aqueous Triton X-100 (5.0 wt %) micellar solution (pH 7.4, 35 °C), which was used as a simple model of biomembranes. The k Q and relative SOAC values were measured using ultraviolet-visible (UV-vis) spectroscopy. The UV-vis absorption spectra of Cars and α-Toc were measured in both a micellar solution and chloroform, to investigate the effect of solvent on the k Q and SOAC values. Furthermore, decay rates (k d ) of 1 O 2 were measured in 0.0, 1.0, 3.0, and 5.0 wt % micellar solutions (pH 7.4), using time-resolved near-infrared fluorescence spectroscopy, to determine the absolute k Q values of the AOs. The results obtained demonstrate that the k Q values of AOs in homogeneous and heterogeneous solutions vary notably depending on (i) the polarity [dielectric constant (ε)] of the reaction field between AOs and 1 O 2 , (ii) the local concentration of AOs, and (iii) the mobility of AOs in solution. In addition, the k Q and relative SOAC values obtained for the Cars in a heterogeneous micellar solution differ remarkably from those in homogeneous organic solvents. Measurements of k Q and SOAC values in a micellar solution may be useful for evaluating the 1 O 2 quenching activity of AOs in biological systems.

Magnetic separation of Dy(III) ions from homogeneous aqueous solutions

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

Pulko, B., E-mail: Barbara.Pulko@tu-dresden.de; Yang, X.; Lei, Z.

2014-12-08

The possibility to enrich paramagnetic dysprosium(III) ions in a magnetic field gradient is proved by means of interferometry, which may open the route for a magnetic separation of rare earth ions from aqueous solutions. The separation dynamics are studied for three different concentrations of DyCl{sub 3} and compared with those found recently in a sulphate solution of the 3d ion Mn(II). In view of the similar-sized hydration spheres for Dy(III) and Mn(II), the slower separation dynamics in DyCl{sub 3} is attributed to both a higher densification coefficient and the strong impact of Brownian motion due to the absence of ion-pairmore » clusters.« less

Pyrene As a New Detector for Determining the Composition of Silver Nanoparticle Dispersions in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Romanovskaya, G. I.; Kazakova, S. Yu.; Koroleva, M. V.; Zuev, B. K.

2018-03-01

It is proposed that the fluorescence of monomeric molecules of pyrene in solid matrices or in concentrated micellar solutions be used as a detector for determining the compositional homogeneity of silver nanoparticle (NP) dispersions in aqueous solutions synthesized in different ways. It is found that the morphology of silver NPs affects the change in the fluorescence intensity of monomeric molecules of pyrene in a certain (violet or blue) region of the pyrene optical spectrum. The observed phenomenon is attributed to the resonance of electronic transitions in the monomeric molecules of pyrene in regions with plasmon oscillations in silver nanoparticles. A new way of obtaining fluorescent silver NPs is found.

Non-equilibrium freezing behaviour of aqueous systems.

PubMed

MacKenzie, A P

1977-03-29

The tendencies to non-equilibrium freezing behaviour commonly noted in representative aqueous systems derive from bulk and surface properties according to the circumstances. Supercooling and supersaturation are limited by heterogeneous nucleation in the presence of solid impurities. Homogeneous nucleation has been observed in aqueous systems freed from interfering solids. Once initiated, crystal growth is ofter slowed and, very frequently, terminated with increasing viscosity. Nor does ice first formed always succeed in assuming its most stable crystalline form. Many of the more significant measurements on a given systeatter permitting the simultaneous representation of thermodynamic and non-equilibrium properties. The diagram incorporated equilibrium melting points, heterogeneous nucleation temperatures, homogeneous nucleation temperatures, glass transition and devitrification temperatures, recrystallization temperatures, and, where appropriate, solute solubilities and eutectic temperatures. Taken together, the findings on modle systems aid the identification of the kinetic and thermodynamic factors responsible for the freezing-thawing survival of living cells.

[Computer modeling the dependences of the membrane potential for polymeric membrane separated non-homogeneous electrolyte solutions on concentration Rayleigh number].

PubMed

Slezak, Izabella H; Jasik-Slezak, Jolanta; Bilewicz-Wyrozumska, Teresa; Slezak, Andrzej

2006-01-01

On the basis of model equation describing the membrane potential delta psi(s) on concentration Rayleigh number (R(C)), mechanical pressure difference (deltaP), concentration polarization coefficient (zeta s) and ratio concentration of solutions separated by membrane (Ch/Cl), the characteristics delta psi(s) = f(Rc)(delta P, zeta s, Ch/Cl) for steady values of zeta s, R(C) and Ch/Cl in single-membrane system were calculated. In this system neutral and isotropic polymeric membrane oriented in horizontal plane, the non-homogeneous binary electrolytic solutions of various concentrations were separated. Nonhomogeneity of solutions is results from creations of the concentration boundary layers on both sides of the membrane. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10(-3) mol x l(-1) (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10(-3) mol x l(-1) to 2 x 10(-2) mol x l(-1) (Ch). Their densities were greater than NaCl solution's at 10(-3) mol x l(-1). It was shown that membrane potential depends on hydrodynamic state of a complex concentration boundary layer-membrane-concentration boundary layer, what is controlled by deltaP, Ch/Cl, Rc and Zeta(s).

The preparation and characterization of monomethoxypoly(ethylene glycol)-b-poly-DL-lactide microcapsules containing bovine hemoglobin.

PubMed

Meng, Fan-Tao; Zhang, Wan-Zhong; Ma, Guang-Hui; Su, Zhi-Guo

2003-08-01

Methoxypoly(ethylene glycol)-b-poly-DL-lactide (PELA) microcapsules containing bovine hemoglobin (bHb) were prepared by a W/O/W double emulsion-solvent diffusion process. bHb solution was used as the internal aqueous phase, PELA/organic solvent as the oil phase, and polyvinyl alcohol (PVA) solution as the external aqueous phase. This W/O/W double emulsion was added into a large volume of water (solidification solution) to allow organic solvent to diffuse into water. The optimum preparative condition for PELA microcapsules loaded with bovine hemoglobin was investigated. It was found that homogenization rate, type of organic solvent, and volume of the solidification solution influenced the activity of bovine hemoglobin encapsulated. When the homogenization rate was lower than 9000 rpm and ethyl acetate was used as the organic solvent, there was no significant influence on the activity of hemoglobin. High homogenization rate as 12 000 rpm decreased the P50 and Hill coefficient. Increasing the volume of solidification solution had an effect of improving the activity of microencapsulated hemoglobin. The composition of the PELA had the most important influence on the success of encapsulation. Microcapsules fabricated by PELA with MPEG2k block (molecular weight of MPEG block: 2000) achieved a high entrapment efficiency of 90%, better than PL A homopolymer and PELA with MPEG5k blocks. Hemoglobin microcapsules with native loading oxygen activity (P50 = 26.0 mmHg, Hill coefficient = 2.4), mean size of about 10 microm, and high entrapment efficiency (ca. 93%) were obtained at the optimum condition.

TRANSFORMATION OF CARBON TETRACHLORIDE IN THE PRESENCE OF SULFIDE, BIOTITE, AND VERMICULITE

EPA Science Inventory

Carbon tetrachloride is transformed in aqueous solutions containing dissolved hydrogen sulfide more rapidly in the presence of the minerals biotite and vermiculite than in homogeneous systems. Approximately 8045% of the CC4 was transformed to COP via the measured intermediate, CS...

Environmental Influences on the Photooxidation of Manganese by a Zinc Porphyrin Sensitizer

NASA Astrophysics Data System (ADS)

Wohlgemuth, Roland; Otvos, John W.; Calvin, Melvin

1982-08-01

The photosensitized oxidation of a membrane-bound Mn(III) tetrapyridylporphyrin derivative by a Zn tetrapyridylporphyrin derivative, which is confined to the membrane, has been achieved in negatively charged membranes consisting of phosphatidylglycerol or phosphatidic acid. At the same time, the zwitterionic electron acceptor, propylviologen sulfonate (PVS0), is reduced in the aqueous phase. The same reaction cannot be obtained with zwitterionic or cationic membranes, nor does this photosensitized reaction take place in a homogeneous solution with Mn(III) tetrapyridylporphyrin and Zn tetrapyridylporphyrin. These results show that the organization of donor, sensitizer, and acceptor at an appropriately selected interface allows reactions that would not occur in homogeneous solutions.

Various nanoparticle morphologies and surface properties of waterborne polyurethane controlled by water

PubMed Central

Zhou, Xing; Fang, Changqing; Lei, Wanqing; Du, Jie; Huang, Tingyi; Li, Yan; Cheng, Youliang

2016-01-01

Water plays important roles in organic reactions such as polyurethane synthesis, and the aqueous solution environment affects polymer morphology and other properties. This paper focuses on the morphology and surface properties of waterborne polyurethane resulting from the organic reaction in water involving different forms (solid and liquid), temperatures and aqueous solutions. We provide evidence from TEM observations that the appearance of polyurethane nanoparticles in aqueous solutions presents diverse forms, including imperfect spheres, perfect spheres, perfect and homogenous spheres and tubes. Based on the results on FTIR, GPC, AFM and XRD experiments, we suggest that the shape of the nanoparticles may be decided by the crimp degree (i.e., the degree of polyurethane chains intertangling in the water environment) and order degree, which are determined by the molecular weight (Mn) and hydrogen bonds. Meanwhile, solid water and high-temperature water can both reduce hard segments that gather on the polyurethane film surface to reduce hydrophilic groups and produce a soft surface. Our findings show that water may play key roles in aqueous polymer formation and bring order to molecular chains. PMID:27687001

Organic crystal-binding peptides: morphology control and one-pot formation of protein-displaying organic crystals

NASA Astrophysics Data System (ADS)

Niide, Teppei; Ozawa, Kyohei; Nakazawa, Hikaru; Oliveira, Daniel; Kasai, Hitoshi; Onodera, Mari; Asano, Ryutaro; Kumagai, Izumi; Umetsu, Mitsuo

2015-11-01

Crystalline assemblies of fluorescent molecules have different functional properties than the constituent monomers, as well as unique optical characteristics that depend on the structure, size, and morphological homogeneity of the crystal particles. In this study, we selected peptides with affinity for the surface of perylene crystal particles by exposing a peptide-displaying phage library in aqueous solution to perylene crystals, eluting the surface-bound phages by means of acidic desorption or liquid-liquid extraction, and amplifying the obtained phages in Escherichia coli. One of the perylene-binding peptides, PeryBPb1: VQHNTKYSVVIR, selected by this biopanning procedure induced perylene molecules to form homogenous planar crystal nanoparticles by means of a poor solvent method, and fusion of the peptide to a fluorescent protein enabled one-pot formation of protein-immobilized crystalline nanoparticles. The nanoparticles were well-dispersed in aqueous solution, and Förster resonance energy transfer from the perylene crystals to the fluorescent protein was observed. Our results show that the crystal-binding peptide could be used for simultaneous control of perylene crystal morphology and dispersion and protein immobilization on the crystals.Crystalline assemblies of fluorescent molecules have different functional properties than the constituent monomers, as well as unique optical characteristics that depend on the structure, size, and morphological homogeneity of the crystal particles. In this study, we selected peptides with affinity for the surface of perylene crystal particles by exposing a peptide-displaying phage library in aqueous solution to perylene crystals, eluting the surface-bound phages by means of acidic desorption or liquid-liquid extraction, and amplifying the obtained phages in Escherichia coli. One of the perylene-binding peptides, PeryBPb1: VQHNTKYSVVIR, selected by this biopanning procedure induced perylene molecules to form homogenous planar crystal nanoparticles by means of a poor solvent method, and fusion of the peptide to a fluorescent protein enabled one-pot formation of protein-immobilized crystalline nanoparticles. The nanoparticles were well-dispersed in aqueous solution, and Förster resonance energy transfer from the perylene crystals to the fluorescent protein was observed. Our results show that the crystal-binding peptide could be used for simultaneous control of perylene crystal morphology and dispersion and protein immobilization on the crystals. Electronic supplementary information (ESI) available: Schematic representation of PeryBPb1-fused DsRed-Monomer, fluorescence spectra of perylene crystals and DsRed-Monomer, and emission spectra of DsRed-Monomer at various excitation wavelengths. See DOI: 10.1039/c5nr06471f

Effect of solute nature on the polyamorphic transition in glassy polyol aqueous solutions.

PubMed

Suzuki, Yoshiharu

2017-08-14

I examined the polyamorphic behavior of glassy dilute aqueous solutions of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol) under pressure at low temperatures. Although the volume change of the glassy aqueous solution varied continuously against pressure, the rate of the volume change appeared to vary discontinuously at the onset pressure of the gradual polyamorphic transition. It is thought that low-density liquid-like solvent water and high-density liquid-like solvent water coexist during the transition. Moreover, the existence of a solute induces the shift of polyamorphic transition to the lower-pressure side. The effect of a solute on the polyamorphic transition becomes larger in the order ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol. Therefore, the solute can become a variable controlling the polyamorphic state of liquid water. This experimental result suggests that the metastable-equilibrium phase boundary between the low-density and the high-density amorphs for pure water is likely to be located at 0.22-0.23 GPa at about 150 K, which is slightly larger than the previously estimated pressure. Moreover, the solute-nature dependence on the polyamorphic transition seems to connect to that on the homogeneous nucleation temperature of polyol aqueous solution at ambient pressure. The region in which a low-density liquid appears coincides with the region in which the nucleus of ice Ih appears, suggesting that the formation of a low-density liquid is a precursory phenomenon of the nucleation of ice Ih.

Effect of solute nature on the polyamorphic transition in glassy polyol aqueous solutions

NASA Astrophysics Data System (ADS)

Suzuki, Yoshiharu

2017-08-01

I examined the polyamorphic behavior of glassy dilute aqueous solutions of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol) under pressure at low temperatures. Although the volume change of the glassy aqueous solution varied continuously against pressure, the rate of the volume change appeared to vary discontinuously at the onset pressure of the gradual polyamorphic transition. It is thought that low-density liquid-like solvent water and high-density liquid-like solvent water coexist during the transition. Moreover, the existence of a solute induces the shift of polyamorphic transition to the lower-pressure side. The effect of a solute on the polyamorphic transition becomes larger in the order ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol. Therefore, the solute can become a variable controlling the polyamorphic state of liquid water. This experimental result suggests that the metastable-equilibrium phase boundary between the low-density and the high-density amorphs for pure water is likely to be located at 0.22-0.23 GPa at about 150 K, which is slightly larger than the previously estimated pressure. Moreover, the solute-nature dependence on the polyamorphic transition seems to connect to that on the homogeneous nucleation temperature of polyol aqueous solution at ambient pressure. The region in which a low-density liquid appears coincides with the region in which the nucleus of ice Ih appears, suggesting that the formation of a low-density liquid is a precursory phenomenon of the nucleation of ice Ih.

Method for fabricating hafnia films

DOEpatents

Hu, Michael Z [Knoxville, TN

2007-08-21

The present invention comprises a method for fabricating hafnia film comprising the steps of providing a substrate having a surface that allows formation of a self-assembled monolayer thereon via covalent bonding; providing an aqueous solution that provides homogeneous hafnium ionic complexes and hafnium nanoclusters wherein the aqueous solution is capable of undergoing homogeneous precipitation under controlled conditions for a desired period of time at a controlled temperature and controlled solution acidity for desired nanocluster nucleation and growth kinetics, desired nanocluster size, desired growth rate of film thickness and desired film surface characteristics. The method further comprising forming the self-assembled monolayer on the surface of the substrate wherein the self-assembled monolayer comprises a plurality of hydrocarbon chains cross-linked together along the surface of the substrate, the hydrocarbon chains being uniformly spaced from one another and wherein each of the hydrocarbon chains having a functional anchoring group at a first end of the chain covalently bonded with the surface of the substrate and each of the hydrocarbon chains having a functional terminating group projected away from the surface wherein the functional terminating group provides a bonding site for the hafnium film to grow; and exposing the substrate to the aqueous solution for a desired period of time at a controlled temperature wherein the hafnium ionic complexes and the hafnium nanoclusters are deposited on the bonding site of the functional terminating group thereby forming the hafnia film wherein the hafnium bonded to the hydrocarbons and to one another provide a uniform ordered arrangement defined by the uniform arrangement of the hydrocarbons.

Homogeneous synthesis of quaternized chitin in NaOH/urea aqueous solution as a potential gene vector.

PubMed

Peng, Na; Ai, Ziye; Fang, Zehong; Wang, Yanfeng; Xia, Zhiping; Zhong, Zibiao; Fan, Xiaoli; Ye, Qifa

2016-10-05

Water-soluble quaternized chitins (QCs) were homogeneously synthesized by reacting chitin with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) in 8wt% NaOH/4wt% urea aqueous solutions. The chemical structure and solution properties of the quaternized chitins were characterized by (1)H NMR, FT-IR, elemental analysis, dynamic light scattering (DLS) and zeta potential measurements. The results demonstrated that the water-soluble QCs, with a degree of substitution (DS) values of 0.27-0.54, could be obtained by varying the concentration of chitin, the molar ratio of CHPTAC to chitin unit, and the reaction time at room temperature (25°C). Two QCs (DS=0.36 and 0.54) were selected and studied as gene carriers. Agarose gel retardation assay revealed that both QCs could condense DNA efficiently when N/P ratio>3. The results of particle size and zeta potential indicated that both QCs had a good ability of condensing plasmid DNA into compact nanoparticles with the size of 100-200nm and zeta potential of +18 to +36mV. Compared to polyethylenimine (PEI, 25kDa), the QCs exhibited outstanding low cytotoxicity. Transfection efficiencies of the QCs/DNA complexes were measured using pGL-3 encoding luciferase as the foreign DNA, and the QCs/DNA complexes showed effective transfection efficiencies in 293T cells. These results revealed that the QCs prepared in NaOH/urea aqueous solutions could be used as promising non-viral gene carriers owing to their excellent characteristics. Copyright © 2016. Published by Elsevier Ltd.

Method for removing trace pollutants from aqueous solutions

DOEpatents

Silver, G.L.

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises: adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 0.1 ppM, and separating the homogeneously precipitated product from the liquid.

Solar chemistry of metal complexes

NASA Astrophysics Data System (ADS)

Gray, H. B.; Maverick, A. W.

1981-12-01

Electronic excited states of certain transition metal complexes undergo oxidation-reduction reactions that store chemical energy. Such reactions have been extensively explored for mononuclear complexes. Two classes of polynuclear species exhibit similar properties, and these complexes are now being studied as possible homogeneous sensitizer-catalysts for hydrogen production from aqueous solutions.

CO.sub.2 separation from low-temperature flue gases

DOEpatents

Dilmore, Robert; Allen, Douglas; Soong, Yee; Hedges, Sheila

2010-11-30

Two methods are provide for the separation of carbon dioxide from the flue gases. The first method utilizes a phase-separating moiety dissolved in an aqueous solution of a basic moiety to capture carbon dioxide. The second method utilizes a phase-separating moiety as a suspended solid in an aqueous solution of a basic moiety to capture carbon dioxide. The first method takes advantage of the surface-independent nature of the CO.sub.2 absorption reactions in a homogeneous aqueous system. The second method also provides permanent sequestration of the carbon dioxide. Both methods incorporate the kinetic rate enhancements of amine-based scrubbing while eliminating the need to heat the entire amine solution (80% water) in order to regenerate and release CO.sub.2. Both methods also take advantage of the low-regeneration temperatures of CO.sub.2-bearing mineral systems such as Na.sub.2CO.sub.3/NaHCO.sub.3 and K.sub.2CO.sub.3/KHCO.sub.3.

Efficient solar-assisted O2 reduction by a cofacial iron porphyrin dimer integrated to a p-CuBi2O4 photocathode prepared by a simple novel method.

PubMed

Zahran, Zaki N; Mohamed, Eman A; Naruta, Yoshinori; Haleem, Ashraf

2017-10-04

A cofacial iron porphyrin hetero-dimer, Fe2TPFPP-TMP showed high electro-catalytic activity, selectivity, and stability for the O2 reduction to H2O both in homogeneous non-aqueous and heterogeneous neutral aqueous solutions. Moreover, when it is integrated to FTO/p-CuBi2O4 (FTO = fluorine doped tin oxide) photocathode prepared by a simple novel method, a remarkable efficient solar-assisted O2 reduction is achieved in neutral potassium phosphate (KPi) or basic NaOH solutions saturated with O2. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Equivalent Aqueous Phase Modulation of Domain Segregation in Myelin Monolayers and Bilayer Vesicles

PubMed Central

Oliveira, Rafael G.; Schneck, Emanuel; Funari, Sergio S.; Tanaka, Motomu; Maggio, Bruno

2010-01-01

Purified myelin can be spread as monomolecular films at the air/aqueous interface. These films were visualized by fluorescence and Brewster angle microscopy, showing phase coexistence at low and medium surface pressures (<20–30 mN/m). Beyond this threshold, the film becomes homogeneous or not, depending on the aqueous subphase composition. Pure water as well as sucrose, glycerol, dimethylsulfoxide, and dimethylformamide solutions (20% in water) produced monolayers that become homogeneous at high surface pressures; on the other hand, the presence of salts (NaCl, CaCl2) in Ringer's and physiological solution leads to phase domain microheterogeneity over the whole compression isotherm. These results show that surface heterogeneity is favored by the ionic milieu. The modulation of the phase-mixing behavior in monolayers is paralleled by the behavior of multilamellar vesicles as determined by small-angle and wide-angle x-ray scattering. The correspondence of the behavior of monolayers and multilayers is achieved only at high surface pressures near the equilibrium adsorption surface pressure; at lower surface pressures, the correspondence breaks down. The equilibrium surface tension on all subphases corresponds to that of the air/alkane interface (27 mN/m), independently on the surface tension of the clean subphase. PMID:20816062

Environmental influences on the photooxidation of manganese by a zinc porphyrin sensitizer

PubMed Central

Wohlgemuth, Roland; Otvos, John W.; Calvin, Melvin

1982-01-01

The photosensitized oxidation of a membrane-bound Mn(III) tetrapyridylporphyrin derivative by a Zn tetrapyridylporphyrin derivative, which is confined to the membrane, has been achieved in negatively charged membranes consisting of phosphatidylglycerol or phosphatidic acid. At the same time, the zwitterionic electron acceptor, propylviologen sulfonate (PVS0), is reduced in the aqueous phase. The same reaction cannot be obtained with zwitterionic or cationic membranes, nor does this photosensitized reaction take place in a homogeneous solution with Mn(III) tetrapyridylporphyrin and Zn tetrapyridylporphyrin. These results show that the organization of donor, sensitizer, and acceptor at an appropriately selected interface allows reactions that would not occur in homogeneous solutions. PMID:16593221

Anthracene and pyrene photolysis kinetics in aqueous, organic, and mixed aqueous-organic phases

NASA Astrophysics Data System (ADS)

Grossman, Jarod N.; Stern, Adam P.; Kirich, Makena L.; Kahan, Tara F.

2016-03-01

Condensed phases in the atmosphere, such as cloud droplets and aerosols, often contain both water and organic matter (OM). Reactivity can differ significantly between aqueous and organic phases. We have measured photolysis kinetics of the polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene in several organic solvents and in water, as well as in miscible and phase-separated aqueous-organic mixtures at atmospherically-relevant wavelengths. Photolysis rate constants generally increased with increasing solvent polarity; photolysis of both PAHs was more than ten times faster in water than in octanol. Local polarity had a much greater effect on PAH photolysis kinetics than changes in PAH absorptivity or singlet oxygen concentrations. Photolysis kinetics in homogeneous aqueous-organic mixtures varied monotonically with2 OM volume fraction. Kinetics in immiscible (phase-separated) solutions were more complex, with different dependences on OM content observed in stagnant and turbulent solutions. Our results suggest that OM could greatly affect the photochemical lifetimes of PAHs in atmospheric condensed phases such as aerosols, even if the OM does not itself absorb photons.

Aggregation of heteropolyanions in aqueous solutions exhibiting short-range attractions and long-range repulsions

DOE PAGES

Bera, Mrinal K.; Qiao, Baofu; Seifert, Soenke; ...

2015-12-15

Charged colloids and proteins in aqueous solutions interact via short-range attractions and long-range repulsions (SALR) and exhibit complex structural phases. These include homogeneously dispersed monomers, percolated monomers, clusters, and percolated clusters. We report the structural architectures of simple charged systems in the form of spherical, Keggin-type heteropolyanions (HPAs) by small-angle X-ray scattering (SAXS) and molecular dynamics (MD) simulations. Structure factors obtained from the SAXS measurements show that the HPAs interact via SALR. Concentration and temperature dependences of the structure factors for HPAs with –3e (e is the charge of an electron) charge are consistent with a mixture of nonassociated monomersmore » and associated randomly percolated monomers, whereas those for HPAs with –4e and –5e charges exhibit only nonassociated monomers in aqueous solutions. Our experiments show that the increase in magnitude of the charge of the HPAs increases their repulsive interactions and inhibits their aggregation in aqueous solutions. MD simulations were done to reveal the atomistic scale origins of SALR between HPAs. As a result, the short-range attractions result from water or proton-mediated hydrogen bonds between neighboring HPAs, whereas the long-range repulsions are due to the distributions of ions surrounding the HPAs.« less

CIDEP study on the flash photolysis of benzoin included in β-cyclodextrin

NASA Astrophysics Data System (ADS)

Kitahama, Yasutaka; Murai, Hisao

1996-10-01

The photodissociation reaction of benzoin (Norrish type I) included in a β-cyclodextrin (CD) cavity in the aqueous phase was studied by using time-resolved ESR and Fourier transform ESR methods. The CIDEP (chemically induced dynamic electron polarization) spectra of α-hydroxybenzyl radical and benzoyl radical were carefully investigated in β-CD, in ethanol, in an ethanol/water mixture, and in saturated aqueous solutions. According to these data and the calculations due to an extended Bloch equation, the spin-lattice relaxation time observed in the β-CD system was compared to those in homogeneous solutions. It is concluded that dissociation takes place from the excited triplet state of benzoin and the fragment radicals are easily ejected from the cavity of β-CD to the aqueous phase much faster than the time-resolution (˜ 20 ns) of the present FT-ESR measurement.

Forward flux sampling calculation of homogeneous nucleation rates from aqueous NaCl solutions.

PubMed

Jiang, Hao; Haji-Akbari, Amir; Debenedetti, Pablo G; Panagiotopoulos, Athanassios Z

2018-01-28

We used molecular dynamics simulations and the path sampling technique known as forward flux sampling to study homogeneous nucleation of NaCl crystals from supersaturated aqueous solutions at 298 K and 1 bar. Nucleation rates were obtained for a range of salt concentrations for the Joung-Cheatham NaCl force field combined with the Extended Simple Point Charge (SPC/E) water model. The calculated nucleation rates are significantly lower than the available experimental measurements. The estimates for the nucleation rates in this work do not rely on classical nucleation theory, but the pathways observed in the simulations suggest that the nucleation process is better described by classical nucleation theory than an alternative interpretation based on Ostwald's step rule, in contrast to some prior simulations of related models. In addition to the size of NaCl nucleus, we find that the crystallinity of a nascent cluster plays an important role in the nucleation process. Nuclei with high crystallinity were found to have higher growth probability and longer lifetimes, possibly because they are less exposed to hydration water.

Forward flux sampling calculation of homogeneous nucleation rates from aqueous NaCl solutions

NASA Astrophysics Data System (ADS)

Jiang, Hao; Haji-Akbari, Amir; Debenedetti, Pablo G.; Panagiotopoulos, Athanassios Z.

2018-01-01

We used molecular dynamics simulations and the path sampling technique known as forward flux sampling to study homogeneous nucleation of NaCl crystals from supersaturated aqueous solutions at 298 K and 1 bar. Nucleation rates were obtained for a range of salt concentrations for the Joung-Cheatham NaCl force field combined with the Extended Simple Point Charge (SPC/E) water model. The calculated nucleation rates are significantly lower than the available experimental measurements. The estimates for the nucleation rates in this work do not rely on classical nucleation theory, but the pathways observed in the simulations suggest that the nucleation process is better described by classical nucleation theory than an alternative interpretation based on Ostwald's step rule, in contrast to some prior simulations of related models. In addition to the size of NaCl nucleus, we find that the crystallinity of a nascent cluster plays an important role in the nucleation process. Nuclei with high crystallinity were found to have higher growth probability and longer lifetimes, possibly because they are less exposed to hydration water.

Magmatic (silicates/saline/sulfur-rich/CO2) immiscibility and zirconium and rare-earth element enrichment from alkaline magma chamber margins : Evidence from Ponza Island, Pontine Archipelago, Italy

USGS Publications Warehouse

Belkin, H.E.; de Vivo, B.; Lima, A.; Torok, K.

1996-01-01

Fluid inclusions were measured from a feldspathoid-bearing syenite xenolith entrained in trachyte from Ponza, one of the islands of the Pontine Archipelago, located in the Gulf of Gaeta, Italy. The feldspathoid-bearing syenite consists mainly of potassium feldspar, clinopyroxene, amphibole, biotite, titanite, manganoan magnetite, apatite with minor nosean, Na-rich feldspar, pyrrhotite, and rare cheralite. Baddeleyite and zirkelite occur associated with manganoan magnetite. Detailed electron-microprobe analysis reveals enrichments in REE, Y, Nb, U, Th as well as Cl and F in appropriate phases. Fluid inclusions observed in potassium feldspar are either silicate-melt or aqueous inclusions. The aqueous inclusions can be further classified as. (1) one-phase vapor, (2) two-phase (V + L) inclusions, vapor-rich inclusions with a small amount of CO2 in most cases; homogenization of the inclusions always occurred in the vapor phase between 359 and 424??C, salinities vary from 2.9 to 8.5 wt. % NaCl equivalent; and. (3) three-phase and multiphase inclusions (hypersaline/sulfur-rich aqueous inclusions sometimes with up to 8 or more solid phases). Daughter minerals dissolve on heating before vapor/liquid homogenization. Standardless quantitative scanning electron microscope X-ray fluorescence analysis has tentatively identified the following chloride and sulfate daughter crystals; halite, sylvite, glauberite. arcanite, anhydrite, and thenardite. Melting of the daughter crystals occurs between 459 and 536??C (54 to 65 wt. % NaCI equivalent) whereas total homogenization is between 640 and 755??C. The occurrence of silicate-melt inclusions and high-temperature, solute-rich aqueous inclusions suggests that the druse or miarolitic texture of the xenolith is late-stage magmatic. The xenolith from Ponza represents a portion of the peripheral magma chamber wall that has recorded the magmatic/hydrothermal transition and the passage of high solute fluids enriched in chlorides, sulfur, and incompatible elements.

Kinetics of de-N-acetylation of the chitin disaccharide in aqueous sodium hydroxide solution.

PubMed

Khong, Thang Trung; Aachmann, Finn L; Vårum, Kjell M

2012-05-01

Chitosan is prepared from chitin, a process which is carried out at highly alkaline conditions, and that can be performed either on chitin in solution (homogeneous deacetylation) or heterogeneously with the chitin as a solid throughout the reaction. We report here a study of the de-N-acetylation reaction of the chitin dimer (GlcNAc-GlcNAc) in solution. The reaction was followed by (1)H NMR spectroscopy in deuterated aqueous sodium hydroxide solution as a function of time, sodium-hydroxide concentration and temperature. The (1)H NMR spectrum of GlcNAc-GlcNAc in 2.77 M deuterated aqueous sodium hydroxide solution was assigned. The interpretation of the (1)H NMR spectra allowed us to determine the rates of de-N-acetylation of the reducing and non-reducing ends, showing that the reaction rate at the reducing end is twice the rate at the non-reducing end. The total deacetylation reaction rate was determined as a function of the hydroxide ion concentration, showing for the first time that this de-N-acetylation reaction is second order with respect to hydroxide ion concentration. No significant difference in the deacetylation rates in deuterated water compared to water was observed. The activation energy for the reaction (26-54 °C) was determined to 114.4 and 98.6 kJ/mol at 2.77 and 5.5 M in deuterated aqueous sodium hydroxide solution, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Method for removing trace pollutants from aqueous solutions

DOEpatents

Silver, Gary L.

1986-01-01

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises, adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 10.sup.-1 ppm, the oxidizing agent being one which oxidizes the contaminant to form an oxidized product which is insoluble in the liquid and precipitates therefrom, and the conditions of the addition being selected to ensure that the precipitation of the oxidized product is homogeneous, and separating the homogeneously precipitated product from the liquid.

NEUTRONIC REACTOR OPERATIONAL METHOD AND CORE SYSTEM

DOEpatents

Winters, C.E.; Graham, C.B.; Culver, J.S.; Wilson, R.H.

1960-07-19

Homogeneous neutronic reactor systems are described wherein an aqueous fuel solution is continuously circulated through a spherical core tank. The pumped fuel solution-is injected tangentially into the hollow spherical interior, thereby maintaining vigorous rotation of the solution within the tank in the form of a vortex; gaseous radiolytic decomposition products concentrate within the axial vortex cavity. The evolved gas is continuously discharged through a gas- outlet port registering with an extremity of the vortex cavity. and the solution stream is discharged through an annular liquid outlet port concentrically encircling the gas outlet by virtue of which the vortex and its cavity are maintained precisely axially aligned with the gas outlet. A primary heat exchanger extracts useful heat from the hot effluent fuel solution before its recirculation into the core tank. Hollow cylinders and other alternative core- tank configurations defining geometric volumes of revolution about a principal axis are also covered. AEC's Homogeneous Reactor Experiment No. 1 is a preferred embodiment.

Population and size distribution of solute-rich mesospecies within mesostructured aqueous amino acid solutions.

PubMed

Jawor-Baczynska, Anna; Moore, Barry D; Lee, Han Seung; McCormick, Alon V; Sefcik, Jan

2013-01-01

Aqueous solutions of highly soluble substances such as small amino acids are usually assumed to be essentially homogenous systems with some degree of short range local structuring due to specific interactions on the sub-nanometre scale (e.g. molecular clusters, hydration shells), usually not exceeding several solute molecules. However, recent theoretical and experimental studies have indicated the presence of much larger supramolecular assemblies or mesospecies in solutions of small organic and inorganic molecules as well as proteins. We investigated both supersaturated and undersaturated aqueous solutions of two simple amino acids (glycine and DL-alanine) using Dynamic Light Scattering (DLS), Brownian Microscopy/Nanoparticles Tracking Analysis (NTA) and Cryogenic Transmission Electron Microscopy (Cryo-TEM). Colloidal scale mesospecies (nanodroplets) were previously reported in supersaturated solutions of these amino acids and were implicated as intermediate species on non-classical crystallization pathways. Surprisingly, we have found that the mesospecies are also present in significant numbers in undersaturated solutions even when the solute concentration is well below the solid-liquid equilibrium concentration (saturation limit). Thus, mesopecies can be observed with mean diameters ranging from 100 to 300 nm and a size distribution that broadens towards larger size with increasing solute concentration. We note that the mesospecies are not a separate phase and the system is better described as a thermodynamically stable mesostructured liquid containing solute-rich domains dispersed within bulk solute solution. At a given temperature, solute molecules in such a mesostructured liquid phase are subject to equilibrium distribution between solute-rich mesospecies and the surrounding bulk solution.

Platelet aggregating material from equine arterial tissue

DOEpatents

Schneider, Morris D.

1983-02-22

Novel hemostatic agent comprises equine arterial fibrillar collagen in a carrier. The agent is useful for the aggregation of platelets for clinical diagnostic tests and for the clotting of blood, such as for controlling bleeding in warm blooded species. The fibrillar collagen is obtained by extracting homogenized equine arterial tissue with aqueous solutions followed by extensive dialysis.

Nano-encapsulation of coenzyme Q10 using octenyl succinic anhydride modified starch

USDA-ARS?s Scientific Manuscript database

Octenyl succinic anhydride modified starch (OSA-ST) was used to encapsulate Coenzyme Q10 (CoQ10). CoQ10 was dissolved in rice bran oil (RBO), and incorporated into an aqueous OSA-ST solution. High pressure homogenization (HPH) of the mixture was conducted at 170 MPa for 5-6 cycles. The resulting ...

Use of LEU in the aqueous homogeneous medical isotope production reactor

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

Ball, R.M.

1997-08-01

The Medical Isotope Production Reactor (MIPR) is an aqueous solution of uranyl nitrate in water, contained in an aluminum cylinder immersed in a large pool of water which can provide both shielding and a medium for heat exchange. The control rods are inserted at the top through re-entrant thimbles. Provision is made to remove radiolytic gases and recombine emitted hydrogen and oxygen. Small quantities of the solution can be continuously extracted and replaced after passing through selective ion exchange columns, which are used to extract the desired products (fission products), e.g. molybdenum-99. This reactor type is known for its largemore » negative temperature coefficient, the small amount of fuel required for criticality, and the ease of control. Calculation using TWODANT show that a 20% U-235 enriched system, water reflected can be critical with 73 liters of solution.« less

Photoinduced oxidation of a water-soluble manganese(III) porphyrin

PubMed Central

Maliyackel, Anthony C.; Otvos, John W.; Spreer, Larry O.; Calvin, Melvin

1986-01-01

The photoinduced oxidation of tetra(N-methyl-4-pyridyl)porphyrinmanganese(III) has been achieved in homogeneous solution. The manganese porphyrin was used as an electron donor in a three-component system with tris-(2,2′-bipyridine)ruthenium(II) as the photosensitizer and chloropentaamminecobalt(III) as the electron acceptor. The photooxidized manganese porphyrin is unstable in aqueous solution, reverting to the starting manganese(III) porphyrin. The oxidation of manganese(III) porphyrin and the subsequent reduction of the oxidized porphyrin can be cycled repeatedly. PMID:16593699

Homogeneously catalysed conversion of aqueous formaldehyde to H2 and carbonate.

PubMed

Trincado, M; Sinha, Vivek; Rodriguez-Lugo, Rafael E; Pribanic, Bruno; de Bruin, Bas; Grützmacher, Hansjörg

2017-04-28

Small organic molecules provide a promising solution for the requirement to store large amounts of hydrogen in a future hydrogen-based energy system. Herein, we report that diolefin-ruthenium complexes containing the chemically and redox non-innocent ligand trop 2 dad catalyse the production of H 2 from formaldehyde and water in the presence of a base. The process involves the catalytic conversion to carbonate salt using aqueous solutions and is the fastest reported for acceptorless formalin dehydrogenation to date. A mechanism supported by density functional theory calculations postulates protonation of a ruthenium hydride to form a low-valent active species, the reversible uptake of dihydrogen by the ligand and active participation of both the ligand and the metal in substrate activation and dihydrogen bond formation.

Ascorbyl radical disproportionation in reverse micellar systems

NASA Astrophysics Data System (ADS)

Gębicki, J. L.; Szymańska-Owczarek, M.; Pacholczyk-Sienicka, B.; Jankowski, S.

2018-04-01

Ascorbyl radical was generated by the pulse radiolysis method and observed with the fast kinetic spectrophotometry within reverse micelles stabilized by AOT in n-heptane or by Igepal CO-520 in cyclohexane at different water to surfactant molar ratio, w0. Rate constants for the disproportionation of the ascorbyl radicals were smaller than those for intermicellar exchange for both type of reverse micelles and slower than those in homogeneous aqueous solutions. However, they increased with increasing w0 for AOT/n-heptane system, while they decreased for Igepal CO-520 system. The absorption spectra of ascorbic acid AOT/n-heptane reverse micellar system showed that the "pH" sensed by this molecule is lower than that in respective homogeneous aqueous solutions. The obtained results were rationalized taking into account three main factors (i) preferential location of ascorbic acid molecules in the interfacial region of the both types of reverse micelles; (ii) postulate that the pH of the interface is lower than that of the water pool of reverse micelles and (iii) different structure of the interface of the reverse micelles made by AOT in n-heptane and those formed by Igepal CO-520 I cyclohexane. Some possible consequences of these findings are discussed.

A New Parameterization of H2SO4/H2O Aerosol Composition: Atmospheric Implications

NASA Technical Reports Server (NTRS)

Tabazadeh, Azadeh; Toon, Owen B.; Clegg, Simon L.; Hamill, Patrick

1997-01-01

Recent results from a thermodynamic model of aqueous sulfuric acid are used to derive a new parameterization for the variation of sulfuric acid aerosol composition with temperature and relative humidity. This formulation is valid for relative humidities above 1 % in the temperature range of 185 to 260 K. An expression for calculating the vapor pressure of supercooled liquid water, consistent with the sulfuric acid model, is also presented. We show that the Steele and Hamill [1981] formulation underestimates the water partial pressure over aqueous H2SOI solutions by up to 12% at low temperatures. This difference results in a corresponding underestimate of the H2SO4 concentration in the aerosol by about 6 % of the weight percent at approximately 190 K. In addition, the relation commonly used for estimating the vapor pressure of H2O over supercooled liquid water differs by up to 10 % from our derived expression. The combined error can result in a 20 % underestimation of water activity over a H2SO4 solution droplet in the stratosphere, which has implications for the parameterization of heterogeneous reaction rates in stratospheric sulfuric acid aerosols. The influence of aerosol composition on the rate of homogeneous ice nucleation from a H2SO4 solution droplet is also discussed. This parameterization can also be used for homogeneous gas phase nucleation calculations of H2SO4 solution droplets under various environmental conditions such as in aircraft exhaust or in volcanic plumes.

Design and in vitro evaluation of a new nano-microparticulate system for enhanced aqueous-phase solubility of curcumin.

PubMed

Guzman-Villanueva, Diana; El-Sherbiny, Ibrahim M; Herrera-Ruiz, Dea; Smyth, Hugh D C

2013-01-01

Curcumin, a yellow polyphenol derived from the turmeric Curcuma longa, has been associated with a diverse therapeutic potential including anti-inflammatory, antioxidant, antiviral, and anticancer properties. However, the poor aqueous solubility and low bioavailability of curcumin have limited its potential when administrated orally. In this study, curcumin was encapsulated in a series of novel nano-microparticulate systems developed to improve its aqueous solubility and stability. The nano-microparticulate systems are based entirely on biocompatible, biodegradable, and edible polymers including chitosan, alginate, and carrageenan. The particles were synthesized via ionotropic gelation. Encapsulating the curcumin into the hydrogel nanoparticles yielded a homogenous curcumin dispersion in aqueous solution compared to the free form of curcumin. Also, the in vitro release profile showed up to 95% release of curcumin from the developed nano-microparticulate systems after 9 hours in PBS at pH 7.4 when freeze-dried particles were used.

Process for Descaling and Decontaminating Metals

DOEpatents

Baybarz, R. D.

1961-04-25

The oxide scale on the surface of stainless steels and similar metals is removed by contacting the metal under an inert atmosphere with a dilute H/sub 2/ SO/sub 4/ solution containing CrSO/sub 4/. The removed oxide scale is either dissolved or disintegrated into a slurry by the solution. Preferred reagent concentrations are 0.3 to 0.5 M CrSO/sub 4/ and 0.5 to 0.6 M H/sub 2/SO/sub 4/. The process is particularly applicable to decontamination of aqueous homogeneous nuclear reactor systems. (AEC)

Hollow-Fibre-Supported Dispersive Liquid-Liquid Microextraction for Determination of Atrazine and Triclosan in Aqueous Samples

PubMed Central

Letseka, Thabiso

2017-01-01

We report the application of the dispersive liquid-liquid microextraction coupled to hollow-fibre membrane-assisted liquid-phase microextraction and its application for extraction of atrazine and triclosan. Under optimum conditions, namely, 25 μL of a 1 : 4 chlorobenzene : ethyl acetate mixture dispersed in 1 mL of aqueous sample, 10% (m/v) NaCl, a magnetic stirrer speed at 600 rpm, and 10 minutes' extraction time with toluene-filled fibre as the acceptor phase, the method demonstrates sufficient figures of merit. These include linearity (R2 ≥ 0.9975), intravial precision (%RSD ≤ 7.6), enrichment factors (127 and 142), limits of detection (0.0081 and 0.0169 µg/mL), and recovery from river water and sewerage (96–101%). The relatively high detection limits are attributed to the flame ionization detector which is less preferred than a mass spectrometer in trace analyses. This is the first report of a homogenous mixture of the dispersed organic solvent in aqueous solutions and its employment in extraction of organic compounds from aqueous solutions. It therefore adds yet another candidate in the pool of miniaturised solvent microextraction techniques. PMID:29158736

Nanodispersive mixed oxides for destruction of warfare agents prepared by homogeneous hydrolysis with urea

NASA Astrophysics Data System (ADS)

Daněk, Ondřej; Štengl, Václav; Bakardjieva, Snejana; Murafa, Nataliya; Kalendová, Andrea; Opluštil, Frantisek

2007-05-01

Nanocrystalline mixed oxides of Ti, Zn, Al and Fe were prepared by a homogeneous hydrolysis of sulphates with urea at temperature of 100 °C in an aqueous solution. The prepared samples were characterized by BET and BJH measurements, an X-ray powder diffraction and scanning electron microscopy. These oxides were taken for an experimental evaluation of their reactivity with yperite (2,2‧-dichloroethyl sulphide), soman (3,3-dimethyl-2-butyl methylphosphonofluoridate) and matter VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothionate). An excellent activity in decomposition of chemical warfare agents was observed in these materials (conversion degree higher then 96%/h).

NEUTRONIC REACTOR COUNTER METHOD AND SYSTEM

DOEpatents

Graham, C.B.; Spiewak, I.

1960-05-31

An improved method is given for controlling the rate of fission in circulating-fuel neutronic reactors in which the fuel is a homogeneous liquid containing fissionable material and a neutron moderator. A change in the rate of flssion is effected by preferentially retaining apart from the circulating fuel a variable amount of either fissionable material or moderator, thereby varying the concentration of fissionable material in the fuel. In the case of an aqueous fuel solution a portion of the water may be continuously vaporized from the circulating solution and the amount of condensate, or condensate plus make-up water, returned to the solution is varied to control the fission rate.

Glass-to-cryogenic-liquid transitions in aqueous solutions suggested by crack healing

PubMed Central

Kim, Chae Un; Tate, Mark W.; Gruner, Sol M.

2015-01-01

Observation of theorized glass-to-liquid transitions between low-density amorphous (LDA) and high-density amorphous (HDA) water states had been stymied by rapid crystallization below the homogeneous water nucleation temperature (∼235 K at 0.1 MPa). We report optical and X-ray observations suggestive of glass-to-liquid transitions in these states. Crack healing, indicative of liquid, occurs when LDA ice transforms to cubic ice at 160 K, and when HDA ice transforms to the LDA state at temperatures as low as 120 K. X-ray diffraction study of the HDA to LDA transition clearly shows the characteristics of a first-order transition. Study of the glass-to-liquid transitions in nanoconfined aqueous solutions shows them to be independent of the solute concentrations, suggesting that they represent an intrinsic property of water. These findings support theories that LDA and HDA ice are thermodynamically distinct and that they are continuously connected to two different liquid states of water. PMID:26351671

Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water.

PubMed

Biddle, John W; Holten, Vincent; Anisimov, Mikhail A

2014-08-21

A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

Innovative approaches for converting a wood hydrolysate to high-quality barrier coatings.

PubMed

Ryberg, Yingzhi Zhu; Edlund, Ulrica; Albertsson, Ann-Christine

2013-08-28

An advanced approach for the efficient and controllable production of softwood hydrolysate-based coatings with excellent oxygen-barrier performance is presented. An innovative conversion of the spray-drying technique into a coating applicator process allowed for a fast and efficient coating process requiring solely aqueous solutions of softwood hydrolysate, even without additives. Compared to analogous coatings prepared by manual application, the spray-drying produced coatings were more homogeneous and smooth, and they adhered more strongly to the substrate. The addition of glyoxal to the aqueous softwood hydrolysate solutions prior to coating formation allowed for hemicellulose cross-linking, which improved both the mechanical integrity and the oxygen-barrier performance of the coatings. A real-time scanning electron microscopy imaging assessment of the tensile deformation of the coatings allowed for a deeper understanding of the ability of the coating layer itself to withstand stress as well as the coating-to-substrate adhesion.

Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re-Os geochronometer to petroleum

NASA Astrophysics Data System (ADS)

Mahdaoui, Fatima; Michels, Raymond; Reisberg, Laurie; Pujol, Magali; Poirier, Yannick

2015-06-01

Several recent studies have raised the exciting possibility that oils can be dated using the Re-Os radioisotope system. However the exact nature of the events dated by this technique often remains unclear. Geochronologic interpretation of Re-Os data for oils is hampered by our limited knowledge of how these metals behave in petroleum systems. In particular, it is difficult to understand how isotopic homogenization, an essential prerequisite for the development of an isochronal relationship, can be achieved at the scale of a petroleum basin. The mechanisms capable of fractionating the Re/Os ratio in a suite of oils are also poorly understood. For this reason, we have performed an experimental study aimed at investigating the behavior of Re and Os during a particularly widespread phenomenon in petroleum systems, the interaction of formation waters with oils during migration. Contact experiments between natural oils and aqueous solutions enriched in Re and/or Os were carried out for varying lengths of time (6 h to 5 months), at different temperatures (25-150 °C), over a wide range of metal concentrations in the enriched solution (0.001-100 μg/g for Re; 1 and 10 ng/g for Os). In addition, the effect of oil composition on Re-Os exchange at the water-oil interface was examined by testing two oils with very different properties. All of our results demonstrate that Re and Os are transferred massively and very rapidly from the aqueous solution to the organic phase. This is true regardless of temperature or oil composition. It is also true for a very wide range of metal concentrations in the aqueous solution, up to an apparent saturation level that exceeds natural concentrations in oils by several orders of magnitude. Given the efficiency of Re and Os transfer from water to oil demonstrated here, and assuming that our findings are applicable to natural conditions, water/oil ratios of only about 250 would be needed to explain the Re and Os contents of most oils, based on the measured concentrations of Re and Os in groundwaters. Thus transfer of Re and Os from formation waters could plausibly provide a source for these metals in oils. Waters from a given basin may have roughly homogeneous Os isotopic compositions, approximating the average value of the source rocks. On the other hand, variable Re/Os ratios might be expected to develop, as a result of interaction with various phases (e.g. Fe-Mn oxides or authigenic pyrite) encountered by the water as it flows through the reservoir. If homogeneous 187Os/188Os ratios coupled with variable Re/Os ratios are transferred to the oils with which the waters come in contact, the isotopic geochronometer could be reset.

Applicability of refractometry for fast routine checking of hospital preparations.

PubMed

Hendrickx, Stijn; Verón, Aurora Monteagudo; Van Schepdael, Ann; Adams, Erwin

2016-04-30

Quality control of hospital pharmacy formulations is of the utmost importance to ensure constant quality and to avoid potential mistakes before administration to the patient. In this study we investigated the applicability of refractometry as a fast, inexpensive and easy-to-use quality control measurement. Refractive indices (RI) of a multitude of different hospital formulations with varying concentrations of active compound were measured. The samples consisted of a number of binary aqueous solutions (one compound in water), complex aqueous solutions (multiple compounds in water or in a constant matrix), two suspensions and one emulsion. For all these formulations, linear regression analysis was performed, quality control limits determined and accuracy and repeatability were checked. Subsequently, actual hospital pharmacy samples were analyzed to check whether they were within the specified limits. For both binary and complex aqueous formulations, repeatability was good and a linear correlation for all samples could be observed on condition that the concentration of the active compound was sufficiently high. The refractometer was not sensitive enough for solutions of folic acid and levothyroxine, which had too low a concentration of active compound. Due to lack of homogeneity and light scattering, emulsions and suspensions do not seem suitable for quality control by refractometry. A mathematical equation was generated to predict the refractive index of an aqueous solution containing clonidine HCl as active compound. Values calculated from the equation were compared with measured values and deviations of all samples were found to be lower than 1.3%. In order to use refractometry in a hospital pharmacy for quality control of multicomponent samples, additional intermediate measurements would be required, to overcome the fact that refractometry is not compound specific. In conclusion, we found that refractometry could potentially be useful for daily, fast quality measurements of relatively concentrated binary and more complex aqueous solutions in the hospital pharmacy. Copyright © 2016 Elsevier B.V. All rights reserved.

Removal of zinc (II) ion from aqueous solution by adsorption onto activated palm midrib bio-sorbent

NASA Astrophysics Data System (ADS)

Mulana, F.; Mariana; Muslim, A.; Mohibah, M.; Halim, K. H. Ku

2018-03-01

In this paper, palm midrib that was activated with mixed citric acid and tartaric acid as biosorbent was used to remove Zn (II) ion from aqueous solution. The aim of this research is to activate palm midrib by using a mixed citric acid and tartaric acid and to determine adsorption capacity of activated palm midrib biosorbent on Zn (II) ion uptake from aqueous solution. The effect of several parameters such as contact time, initial Zn (II) ion concentration and activator concentration on the degree of Zn (II) ion removal was examined. Atomic Absorption Spectroscopy method was performed to determine adsorbed amount of Zn (II) ion into activated biosorbent. The result showed that the adsorption process was relatively not so fast and equilibrium was reached after contact time of 120 min. The adsorption capacity of biosorbent reached a maximum when the concentration of mixed citric acid and tartaric acid was 1.6 M. The optimum adsorption capacity was 5.72 mg/g. The result was obtained on initial Zn (II) ion concentration of 80 ppm for 120-min contact time. Langmuir isotherm was found as the best fit for the equilibrium data indicating homogeneous adsorption of metal ions onto the biosorbent surface.

Multicomponent amorphous nanofibers electrospun from hot aqueous solutions of a poorly soluble drug.

PubMed

Yu, Deng-Guang; Gao, Li-Dong; White, Kenneth; Branford-White, Christopher; Lu, Wei-Yue; Zhu, Li-Min

2010-11-01

To design and fabricate multicomponent amorphous electrospun nanofibers for synergistically improving the dissolution rate and permeation profiles of poorly water-soluble drugs. Nanofibers were designed to be composed of a poorly water soluble drug, helicid, a hydrophilic polymer polyvinylpyrrolidone as filament-forming matrix, sodium dodecyl sulfate as transmembrane enhancer and mannitol as taste masking agent, and were prepared from hot aqueous co-dissolving solutions of them. An elevated temperature electrospinning process was developed to fabricate the composite nanofibers, which were characterized using FESEM, DSC, XRD, ATR-FTIR, in vitro dissolution and permeation tests. The composite nanofibers were homogeneous with smooth surfaces and uniform structure, and the components were combined together in an amorphous state because of the favorable interactions such as hydrogen bonding, electrostatic interaction and hydrophobic interactions among them. In vitro dissolution and permeation tests demonstrated that the composite nanofibers had a dissolution rate over 26-fold faster than that of crude helicid particles and a 10-fold higher permeation rate across sublingual mucosa. A new type of amorphous material in the form of nanofibers was prepared from hot aqueous solutions of multiple ingredients using an electrospinning process. The amorphous nanofibers were able to improve the dissolution rate and permeation rate of helicid.

Neutron Absorbing Alloys

DOEpatents

Zhong, Yuanzhen , Parikh, Hemant; Smith, Terry E.

2002-05-28

A process for making homogeneous copolymers of vinylpyrrolidone (VP) and vinyl acetate (VA) which form clear aqueous solutions and have high cloud points. The process involves precharging VP and VA monomers in a predetermined ratio, and then feeding VP and VA at a predetermined rate, the ratio of the components in the initial charge and the feeding rates for the monomer being selected in accordance with the reactivity rates of the monomers towards copolymerization as opposed to homopolymerization.

Method for immobilizing radioactive iodine

DOEpatents

Babad, Harry; Strachan, Denis M.

1980-01-01

Radioactive iodine, present as alkali metal iodides or iodates in an aqueous solution, is incorporated into an inert solid material for long-term storage by adding to the solution a stoichiometric amount with respect to the formation of a sodalite (3M.sub.2 O.3Al.sub.2 O.sub.3. 6SiO.sub.2.2MX, where M=alkali metal; X=I.sup.- or IO.sub.3.sup.-) of an alkali metal, alumina and silica, stirring the solution to form a homogeneous mixture, drying the mixture to form a powder, compacting and sintering the compacted powder at 1073 to 1373 K (800.degree. to 1100.degree. C.) for a time sufficient to form sodalite.

Synthesis and characterization of supported polysugar-stabilized palladium nanoparticle catalysts for enhanced hydrodechlorination of trichloroethylene

NASA Astrophysics Data System (ADS)

Bacik, Deborah B.; Zhang, Man; Zhao, Dongye; Roberts, Christopher B.; Seehra, Mohinar S.; Singh, Vivek; Shah, Naresh

2012-07-01

Palladium (Pd) nanoparticle catalysts were successfully synthesized within an aqueous phase using sodium carboxymethyl cellulose (CMC) as a capping ligand which offers a green alternative to conventional nanoparticle synthesis techniques. The CMC-stabilized Pd nanoparticles were subsequently dispersed within support materials using the incipient wetness impregnation technique for utilization in heterogeneous catalyst systems. The unsupported and supported (both calcined and uncalcined) Pd nanoparticle catalysts were characterized using transmission electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction, and Brunauer-Emmett-Teller surface area measurement and their catalytic activity toward the hydrodechlorination of trichloroethylene (TCE) in aqueous media was examined using homogeneous and heterogeneous catalyst systems, respectively. The unsupported Pd nanoparticles showed considerable activity toward the degradation of TCE, as demonstrated by the reaction kinetics. Although the supported Pd nanoparticle catalysts had a lower catalytic activity than the unsupported particles that were homogeneously dispersed in the aqueous solutions, the supported catalysts retained sufficient activity toward the degradation of TCE. In addition, the use of the hydrophilic Al2O3 support material induced a mass transfer resistance to TCE that affected the initial hydrodechlorination rate. This paper demonstrates that supported Pd catalysts can be applied to the heterogeneous catalytic hydrodechlorination of TCE.

The Origin of Dark Inclusions in Allende: New Evidence from Lithium Isotopes

NASA Technical Reports Server (NTRS)

Sephton, Mark A.; James, Rachael H.; Zolensky, Michael E.

2006-01-01

Aqueous and thermal processing of primordial material occurred prior to and during planet formation in the early solar system. A record of how solid materials were altered at this time is present in the carbonaceous chondrites, which are naturally delivered fragments of primitive asteroids. It has been proposed that some materials, such as the clasts termed dark inclusions found in type III chondrites, suggest a sequence of aqueous and thermal events. Lithium isotopes (Li-6 and Li-7) can reveal the role of liquid water in dark inclusion history. During aqueous alteration, Li-7 passes preferentially into solution leaving Li-6 behind in the solid phase and, consequently, any relatively extended periods of interaction with Li-7-rich fluids would have left the dark inclusions enriched in the heavier isotope when compared to the meteorite as a whole. Our analyses of lithium isotopes in Allende and its dark inclusions reveal marked isotopic homogeneity and no evidence of greater levels of aqueous alteration in dark inclusion history.

Layered zinc hydroxide nanocones: synthesis, facile morphological and structural modification, and properties

NASA Astrophysics Data System (ADS)

Ma, Wei; Ma, Renzhi; Liang, Jianbo; Wang, Chengxiang; Liu, Xiaohe; Zhou, Kechao; Sasaki, Takayoshi

2014-10-01

Layered zinc hydroxide nanocones intercalated with DS- have been synthesized for the first time via a convenient synthetic approach, using homogeneous precipitation in the presence of urea and sodium dodecyl sulfate (SDS). SDS plays a significant role in controlling the morphologies of as-synthesized samples. Conical samples intercalated with various anions were transformed through an anion-exchange route in ethanol solution, and the original conical structure was perfectly maintained. Additionally, these DS--inserted nanocones can be transformed into square-like nanoplates in aqueous solution at room temperature, fulfilling the need for different morphology-dependent properties. Corresponding ZnO nanocones and nanoplates have been further obtained through the thermal calcination of NO3--intercalating zinc hydroxide nanocones/nanoplates. These ZnO nanostructures with different morphologies exhibit promising photocatalytic properties.Layered zinc hydroxide nanocones intercalated with DS- have been synthesized for the first time via a convenient synthetic approach, using homogeneous precipitation in the presence of urea and sodium dodecyl sulfate (SDS). SDS plays a significant role in controlling the morphologies of as-synthesized samples. Conical samples intercalated with various anions were transformed through an anion-exchange route in ethanol solution, and the original conical structure was perfectly maintained. Additionally, these DS--inserted nanocones can be transformed into square-like nanoplates in aqueous solution at room temperature, fulfilling the need for different morphology-dependent properties. Corresponding ZnO nanocones and nanoplates have been further obtained through the thermal calcination of NO3--intercalating zinc hydroxide nanocones/nanoplates. These ZnO nanostructures with different morphologies exhibit promising photocatalytic properties. Electronic supplementary information (ESI) available: Typical SEM images, TGA curves and XRD patterns of as-prepared samples. See DOI: 10.1039/c4nr04166f

Stability of fluctuating and transient aggregates of amphiphilic solutes in aqueous binary mixtures: Studies of dimethylsulfoxide, ethanol, and tert-butyl alcohol

NASA Astrophysics Data System (ADS)

Banerjee, Saikat; Bagchi, Biman

2013-10-01

In aqueous binary mixtures, amphiphilic solutes such as dimethylsulfoxide (DMSO), ethanol, tert-butyl alcohol (TBA), etc., are known to form aggregates (or large clusters) at small to intermediate solute concentrations. These aggregates are transient in nature. Although the system remains homogeneous on macroscopic length and time scales, the microheterogeneous aggregation may profoundly affect the properties of the mixture in several distinct ways, particularly if the survival times of the aggregates are longer than density relaxation times of the binary liquid. Here we propose a theoretical scheme to quantify the lifetime and thus the stability of these microheterogeneous clusters, and apply the scheme to calculate the same for water-ethanol, water-DMSO, and water-TBA mixtures. We show that the lifetime of these clusters can range from less than a picosecond (ps) for ethanol clusters to few tens of ps for DMSO and TBA clusters. This helps explaining the absence of a strong composition dependent anomaly in water-ethanol mixtures but the presence of the same in water-DMSO and water-TBA mixtures.

Evaporation-Driven Deposition of ITO Thin Films from Aqueous Solutions with Low-Speed Dip-Coating Technique.

PubMed

Ito, Takashi; Uchiyama, Hiroaki; Kozuka, Hiromitsu

2017-05-30

We suggest a novel wet coating process for preparing indium tin oxide (ITO) films from simple solutions containing only metal salts and water via evaporation-driven film deposition during low-speed dip coating. Homogeneous ITO precursor films were deposited on silica glass substrates from the aqueous solutions containing In(NO 3 ) 3 ·3H 2 O and SnCl 4 ·5H 2 O by dip coating at substrate withdrawal speeds of 0.20-0.50 cm min -1 and then crystallized by the heat treatment at 500-800 °C for 10-60 min under N 2 gas flow of 0.5 L min -1 . The ITO films heated at 600 °C for 30 min had a high optical transparency in the visible range and a good electrical conductivity. Multiple-coating ITO films obtained with five-times dip coating exhibited the lowest sheet (ρ S ) and volume (ρ V ) resistivities of 188 Ω sq -1 and 4.23 × 10 -3 Ω cm, respectively.

Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

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

Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A., E-mail: anisimov@umd.edu

2014-08-21

A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H{sub 2}O-NaCl and H{sub 2}O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archermore » and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.« less

High-performance magnetic carbon materials in dye removal from aqueous solutions

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

Gao, Xiaoming, E-mail: dawn1026@163.com; Zhang, Yu; Dai, Yuan

To obtain a novel adsorbent with excellent adsorption capacity and convenient magnetic separation property, magnetic activated semi-coke was prepared by KOH activation method and further modified by FeCl{sub 3}. The surface morphology, physical structure, chemical properties and textural characteristics of unmodified semi-coke, KOH-modified semi-coke and magnetic activated semi-coke were characterized by scanning electron microscopy, X-ray powder diffraction, N{sub 2} adsorption-desorption measurement, and electronic differential system. The adsorption characteristics of the magnetic activated semi-coke were explored for the removal of methyl orang (MO), methylene blue (MB), congo red (CR), acid fuchsin (AF), and rhodamine B (RB) from aqueous solution. The effectsmore » of adsorption parameters, including adsorbent dosage, pH and contact time, were investigated by comparing the adsorption properties of the magnetic activated semi-coke to RB. The result showed that the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. The adsorption experiment data indicated that the pseudosecond order model and the Langmuir model could well explain the adsorption processes of RB on the magnetic activated semi-coke, and the maximum adsorption capacity (q{sub m}) was 526.32 mg/g. The values of thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that the adsorption process depended on the temperature of the aqueous phase, and it was spontaneous and exothermic in nature. As the addition of the magnetic activated semi-coke, the color of the solution significantly faded. Subsequently, fast aggregation of the magnetic activated semi-coke from their homogeneous dispersion in the presence of an external magnetic field could be happened. So, the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. - Graphical abstract: As the addition of the magnetic activated semi-coke, the color of the solution significantly faded. Subsequently, fast aggregation of the magnetic activated semi-coke from their homogeneous dispersion in the presence of an external magnetic field could be happened. So, the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. Display Omitted.« less

A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials

NASA Astrophysics Data System (ADS)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping

2015-08-01

The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds.

Nonequilibrium Self-Assembly of π-Conjugated Oligopeptides in Solution.

PubMed

Li, Bo; Li, Songsong; Zhou, Yuecheng; Ardoña, Herdeline Ann M; Valverde, Lawrence R; Wilson, William L; Tovar, John D; Schroeder, Charles M

2017-02-01

Supramolecular assembly is a powerful method that can be used to generate materials with well-defined structures across multiple length scales. Supramolecular assemblies consisting of biopolymer-synthetic polymer subunits are specifically known to exhibit exceptional structural and functional diversity as well as programmable control of noncovalent interactions through hydrogen bonding in biopolymer subunits. Despite recent progress, there is a need to control and quantitatively understand assembly under nonequilibrium conditions. In this work, we study the nonequilibrium self-assembly of π-conjugated synthetic oligopeptides using a combination of experiments and analytical modeling. By isolating an aqueous peptide solution droplet within an immiscible organic layer, the rate of peptide assembly in the aqueous solution can be controlled by tuning the transport rate of acid that is used to trigger assembly. Using this approach, peptides are guided to assemble under reaction-dominated and diffusion-dominated conditions, with results showing a transition from a diffusion-limited reaction front to spatially homogeneous assembly as the transport rate of acid decreases. Interestingly, our results show that the morphology of self-assembled peptide fibers is controlled by the assembly kinetics such that increasingly homogeneous structures of self-assembled synthetic oligopeptides were generally obtained using slower rates of assembly. We further developed an analytical reaction-diffusion model to describe oligopeptide assembly, and experimental results are compared to the reaction-diffusion model across a range of parameters. Overall, this work highlights the importance of molecular self-assembly under nonequilibrium conditions, specifically showing that oligopeptide assembly is governed by a delicate balance between reaction kinetics and transport processes.

Nonpolymeric nanoassemblies for ocular administration of acyclovir: pharmacokinetic evaluation in rabbits.

PubMed

Stella, Barbara; Arpicco, Silvia; Rocco, Flavio; Burgalassi, Susi; Nicosia, Nadia; Tampucci, Silvia; Chetoni, Patrizia; Cattel, Luigi

2012-01-01

The aim of this study was to increase bioavailability of the antiviral drug acyclovir (ACV) when administered by the ocular route. For this purpose, a new lipophilic derivative of acyclovir was synthesized, both possessing greater lipophilicity and providing the formation of a homogeneous water dispersion with higher amount of ACV than the aqueous solution of the parent drug. This was done by chemically linking acyclovir to the isoprenoid chain of squalene, obtaining 4'-trisnorsqualenoylacyclovir (SQACV), in which squalene is covalently coupled to the 4'-hydroxy group of acyclovir. This new prodrug was then formulated as nonpolymeric nanoassemblies through nanoprecipitation; the resulting particles were characterized in terms of mean diameter, zeta potential, and stability. The pharmacokinetic profile of the prodrug in the tear fluid and in the aqueous humor of rabbits was evaluated and compared to that of the parent drug. Data showed that SQACV nanoassemblies increased the amount of ACV in the aqueous humor of rabbits compared to free ACV solution. This new amphiphilic prodrug of acyclovir is a very promising tool to increase the ocular bioavailability of the parent drug. Copyright © 2011 Elsevier B.V. All rights reserved.

Superacid-Surfactant Exchange: Enabling Nondestructive Dispersion of Full-Length Carbon Nanotubes in Water.

PubMed

Wang, Peng; Kim, Mijin; Peng, Zhiwei; Sun, Chuan-Fu; Mok, Jasper; Lieberman, Anna; Wang, YuHuang

2017-09-26

Attaining aqueous solutions of individual, long single-walled carbon nanotubes is a critical first step for harnessing the extraordinary properties of these materials. However, the widely used ultrasonication-ultracentrifugation approach and its variants inadvertently cut the nanotubes into short pieces. The process is also time-consuming and difficult to scale. Here we present an unexpectedly simple solution to this decade-old challenge by directly neutralizing a nanotube-chlorosulfonic acid solution in the presence of sodium deoxycholate. This straightforward superacid-surfactant exchange eliminates the need for both ultrasonication and ultracentrifugation altogether, allowing aqueous solutions of individual nanotubes to be prepared within minutes and preserving the full length of the nanotubes. We found that the average length of the processed nanotubes is more than 350% longer than sonicated controls, with a significant fraction approaching ∼9 μm, a length that is limited by only the raw material. The nondestructive nature is manifested by an extremely low density of defects, bright and homogeneous photoluminescence in the near-infrared, and ultrahigh electrical conductivity in transparent thin films (130 Ω/sq at 83% transmittance), which well exceeds that of indium tin oxide. Furthermore, we demonstrate that our method is fully compatible with established techniques for sorting nanotubes by their electronic structures and can also be readily applied to graphene. This surprisingly simple method thus enables nondestructive aqueous solution processing of high-quality carbon nanomaterials at large-scale and low-cost with the potential for a wide range of fundamental studies and applications, including, for example, transparent conductors, near-infrared imaging, and high-performance electronics.

Homogenous Surface Nucleation of Solid Polar Stratospheric Cloud Particles

NASA Technical Reports Server (NTRS)

Tabazadeh, A.; Hamill, P.; Salcedo, D.; Gore, Warren J. (Technical Monitor)

2002-01-01

A general surface nucleation rate theory is presented for the homogeneous freezing of crystalline germs on the surfaces of aqueous particles. While nucleation rates in a standard classical homogeneous freezing rate theory scale with volume, the rates in a surface-based theory scale with surface area. The theory is used to convert volume-based information on laboratory freezing rates (in units of cu cm, seconds) of nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD) aerosols into surface-based values (in units of sq cm, seconds). We show that a surface-based model is capable of reproducing measured nucleation rates of NAT and NAD aerosols from concentrated aqueous HNO3 solutions in the temperature range of 165 to 205 K. Laboratory measured nucleation rates are used to derive free energies for NAT and NAD germ formation in the stratosphere. NAD germ free energies range from about 23 to 26 kcal mole, allowing for fast and efficient homogeneous NAD particle production in the stratosphere. However, NAT germ formation energies are large (greater than 26 kcal mole) enough to prevent efficient NAT particle production in the stratosphere. We show that the atmospheric NAD particle production rates based on the surface rate theory are roughly 2 orders of magnitude larger than those obtained from a standard volume-based rate theory. Atmospheric volume and surface production of NAD particles will nearly cease in the stratosphere when denitrification in the air exceeds 40 and 78%, respectively. We show that a surface-based (volume-based) homogeneous freezing rate theory gives particle production rates, which are (not) consistent with both laboratory and atmospheric data on the nucleation of solid polar stratospheric cloud particles.

Physical properties of aqueous solutions of a thermo-responsive neutral copolymer and an anionic surfactant: turbidity and small-angle neutron scattering studies.

PubMed

Galant, Céline; Kjøniksen, Anna-Lena; Knudsen, Kenneth D; Helgesen, Geir; Lund, Reidar; Laukkanen, Antti; Tenhu, Heikki; Nyström, Bo

2005-08-16

Aqueous mixtures of the anionic sodium dodecyl sulfate (SDS) surfactant and thermo-responsive poly(N-vinylcaprolactam) chains grafted with omega-methoxy poly(ethylene oxide) undecyl alpha-methacrylate (PVCL-g-C11EO42) have been characterized using turbidimetry and small-angle neutron scattering (SANS). Turbidity measurements show that the addition of SDS to a dilute aqueous copolymer solution (1.0 wt %) induces an increase of the cloud point (CP) value and a decrease of the turbidity at high temperatures. In parallel, SANS results show a decrease of both the average distance between chains and the global size of the objects in solution at high temperatures as the SDS concentration is increased. Combination of these findings reveals that the presence of SDS in the PVCL-g-C11EO42 solutions (1.0 wt %) promotes the formation of smaller aggregates and, consequently, leads to a more homogeneous distribution of the chains in solution upon heating of the mixtures. Moreover, the SANS data results show that the internal structure of the formed aggregates becomes more swollen as the SDS concentration increases. On the other hand, the addition of moderate amounts of SDS (up to 4 mm) to a semidilute copolymer solution (5.0 wt %) gives rise to a more pronounced aggregation as the temperature rises; turbidity and SANS studies reveal in this case a decrease of the CP value and an increase of the scattered intensity at low q. The overall picture that emerges from this study is that the degree of aggregation can be accurately tuned by varying parameters such as the temperature, level of surfactant addition, and polymer concentration.

Influence of palmitoyl pentapeptide and Ceramide III B on the droplet size of nanoemulsion

NASA Astrophysics Data System (ADS)

Sondari, Dewi; Haryono, Agus; Harmami, Sri Budi; Randy, Ahmad

2010-05-01

The influence of the Palmitoyl Pentapeptide (PPp) and Ceramide IIIB (Cm III B) as active ingredients on the droplet size of nano-emulsion was studied using different kinds of oil (avocado oil, sweet almond oil, jojoba oil, mineral oil and squalene). The formation of nano-emulsions were prepared in water mixed non ionic surfactant/oils system using the spontaneous emulsification mechanism. The aqueous solution, which consist of water and Tween® 20 as a hydrophilic surfactant was mixed homogenously. The organic solution, which consist of oil and Span® 80 as a lipophilic surfactant was mixed homogenously in ethanol. Ethanol was used as a water miscible solvent, which can help the formation of nano-emulsion. The oil phase (containing the blend of surfactant Span® 80, ethanol, oil and active ingredient) and the aqueous phase (containing water and Tween® 20) were separately prepared at room temperatures. The oil phase was slowly added into aqueous phase under continuous mechanical agitation (18000 rpm). All samples were subsequently homogenized with Ultra-Turrax for 30 minutes. The characterizations of nano-emulsion were carried out using photo-microscope and particle size analyzer. Addition of active ingredients on the formation of nano-emulsion gave smallest droplet size compared without active ingredients addition on the formation of nano-emulsion. Squalene oil with Palmitoyl Pentapeptide (PPm) and Ceramide IIIB (Cm IIIB) gave smallest droplet size (184.0 nm) compared without Palmitoyl Pentapeptide and Ceramide IIIB (214.9 nm), however the droplets size of the emulsion prepared by the other oils still in the range of nano-emulsion (below 500 nm). The stability of nano-emulsion was observed using two methods. In one method, the stability of nano-emulsion was observed for three months at temperature of 5°C and 50°C, while in the other method, the stability nano-emulsion was observed by centrifuged at 12000 rpm for 30 minutes. Nanoemulsion with active ingredient was remained stable even when stored until three months. Coalescence process between the droplets was not occurred significantly and droplet size was still below 500 nm. Over all, the emulsion remained stable, even it was centrifuged at 12000 rpm for 30 minutes.

Tandem Lewis/Brønsted homogeneous acid catalysis: conversion of glucose to 5-hydoxymethylfurfural in an aqueous chromium(iii) chloride and hydrochloric acid solution

DOE PAGES

Swift, T. Dallas; Nguyen, Hannah; Anderko, Andrzej; ...

2015-07-25

Here, a kinetic model for the tandem conversion of glucose to 5-hydroxymethylfurfural (HMF) through fructose in aqueous CrCl 3–HCl solution was developed by analyzing experimental data. We show that the coupling of Lewis and Brønsted acids in a single pot overcomes equilibrium limitations of the glucose–fructose isomerization leading to high glucose conversions and identify conditions that maximize HMF yield. Adjusting the HCl/CrCl 3 concentration has a more pronounced effect on HMF yield at constant glucose conversion than that of temperature or CrCl 3 concentration. This is attributed to the interactions between HCl and CrCl 3 speciation in solution that leadsmore » to HMF yield being maximized at moderate HCl concentrations for each CrCl 3 concentration. This volcano-like behavior is accompanied with a change in the rate-limiting step from fructose dehydration to glucose isomerization as the concentration of the Brønsted acid increases. The maximum HMF yield in a single aqueous phase is only modest and appears independent of catalysts’ concentrations as long as they are appropriately balanced. However, it can be further maximized in a biphasic system. Our findings are consistent with recent studies in other tandem reactions catalyzed by different catalysts.« less

Dehydration induced phase transitions in a microfluidic droplet array for the separation of biomolecules

NASA Astrophysics Data System (ADS)

Nelson, Chris; Anna, Shelley

2013-11-01

Droplet-based strategies for fluid manipulation have seen significant application in microfluidics due to their ability to compartmentalize solutions and facilitate highly parallelized reactions. Functioning as micro-scale reaction vessels, droplets have been used to study protein crystallization, enzyme kinetics, and to encapsulate whole cells. Recently, the mass transport out of droplets has been used to concentrate solutions and induce phase transitions. Here, we show that droplets trapped in a microfluidic array will spontaneously dehydrate over the course of several hours. By loading these devices with an initially dilute aqueous polymer solution, we use this slow dehydration to observe phase transitions and the evolution of droplet morphology in hundreds of droplets simultaneously. As an example, we trap and dehydrate droplets of a model aqueous two-phase system consisting of polyethylene glycol and dextran. Initially the drops are homogenous, then after some time the polymer concentration reaches a critical point and two phases form. As water continues to leave the system, the drops transition from a microemulsion of DEX in PEG to a core-shell configuration. Eventually, changes in interfacial tension, driven by dehydration, cause the DEX core to completely de-wet from the PEG shell. Since aqueous two phase systems are able to selectively separate a variety of biomolecules, this core shedding behavior has the potential to provide selective, on-chip separation and concentration.

Tandem Lewis/Brønsted homogeneous acid catalysis: conversion of glucose to 5-hydoxymethylfurfural in an aqueous chromium(iii) chloride and hydrochloric acid solution

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

Swift, T. Dallas; Nguyen, Hannah; Anderko, Andrzej

Here, a kinetic model for the tandem conversion of glucose to 5-hydroxymethylfurfural (HMF) through fructose in aqueous CrCl 3–HCl solution was developed by analyzing experimental data. We show that the coupling of Lewis and Brønsted acids in a single pot overcomes equilibrium limitations of the glucose–fructose isomerization leading to high glucose conversions and identify conditions that maximize HMF yield. Adjusting the HCl/CrCl 3 concentration has a more pronounced effect on HMF yield at constant glucose conversion than that of temperature or CrCl 3 concentration. This is attributed to the interactions between HCl and CrCl 3 speciation in solution that leadsmore » to HMF yield being maximized at moderate HCl concentrations for each CrCl 3 concentration. This volcano-like behavior is accompanied with a change in the rate-limiting step from fructose dehydration to glucose isomerization as the concentration of the Brønsted acid increases. The maximum HMF yield in a single aqueous phase is only modest and appears independent of catalysts’ concentrations as long as they are appropriately balanced. However, it can be further maximized in a biphasic system. Our findings are consistent with recent studies in other tandem reactions catalyzed by different catalysts.« less

Preparation of Cu-loaded SrTiO3 nanoparticles and their photocatalytic activity for hydrogen evolution from methanol aqueous solution

NASA Astrophysics Data System (ADS)

Bui, Duc-Nguyen; Mu, Jin; Wang, Lei; Kang, Shi-Zhao; Li, Xiangqing

2013-06-01

Cu-loaded SrTiO3 nanoparticles (Cu-SrTiO3) were prepared using a simple in situ photo-deposition method and their photocatalytic activity for hydrogen evolution from methanol aqueous solution was evaluated. The results characterized with XRD, TEM, XPS and EDX indicated that the as-synthesized sample was composed of metallic Cu and cubic SrTiO3, and the metallic Cu was homogeneously loaded on the surface of SrTiO3 nanoparticles. Under UV light irradiation, Cu-SrTiO3 displayed much higher photocatalytic activity for hydrogen evolution and excellent stability in comparison with pure SrTiO3 nanoparticles. The results further confirmed that the efficient separation of photogenerated electron/hole pairs was critical for the enhanced photocatalytic activity of Cu-SrTiO3. Moreover, the rate of hydrogen evolution of 0.5 wt.% Cu-SrTiO3 is comparable with that of 0.5 wt.% Pt-SrTiO3 photocatalyst under optimum conditions, implying that the metallic Cu is an efficient alternative to Pt as a co-catalyst on SrTiO3. The high photocatalytic activity, low cost and chemical stability mean that the Cu-loaded SrTiO3 is a potential catalyst for the photocatalytic hydrogen evolution from methanol aqueous solution.

Silicon-on-insulator based nanopore cavity arrays for lipid membrane investigation.

PubMed

Buchholz, K; Tinazli, A; Kleefen, A; Dorfner, D; Pedone, D; Rant, U; Tampé, R; Abstreiter, G; Tornow, M

2008-11-05

We present the fabrication and characterization of nanopore microcavities for the investigation of transport processes in suspended lipid membranes. The cavities are situated below the surface of silicon-on-insulator (SOI) substrates. Single cavities and large area arrays were prepared using high resolution electron-beam lithography in combination with reactive ion etching (RIE) and wet chemical sacrificial underetching. The locally separated compartments have a circular shape and allow the enclosure of picoliter volume aqueous solutions. They are sealed at their top by a 250 nm thin Si membrane featuring pores with diameters from 2 µm down to 220 nm. The Si surface exhibits excellent smoothness and homogeneity as verified by AFM analysis. As biophysical test system we deposited lipid membranes by vesicle fusion, and demonstrated their fluid-like properties by fluorescence recovery after photobleaching. As clearly indicated by AFM measurements in aqueous buffer solution, intact lipid membranes successfully spanned the pores. The nanopore cavity arrays have potential applications in diagnostics and pharmaceutical research on transmembrane proteins.

Use of hydroxypropyl-β-cyclodextrin/polyethylene glycol 400, modified Fe3O4 nanoparticles for congo red removal.

PubMed

Yu, Lan; Xue, Weihua; Cui, Lei; Xing, Wen; Cao, Xinli; Li, Hongyu

2014-03-01

Fe3O4 nanoparticles were modified with Hydroxypropyl-β-cyclodextrin (HP-β-CD) and Polyethylene glycol 400 (PEG400) by a facile one-pot homogeneous precipitation method, and were used as a novel nano-adsorbent for the removal of congo red (CR) from aqueous solutions. The polymer-modified composites were characterized by FTIR, TEM, TGA, XRD and VSM, and showed excellent adsorption efficiency for CR. The value of the maximum adsorption capacity calculated according to the Langmuir isotherm model were 1.895g/g, which are much high and about 19 times that of Fe3O4 nanoparticles. Desorption study further indicates the good regeneration ability of the nanocomposites. The results suggest that the HP-β-CD/PEG400-modified Fe3O4 nanoparticles is a promising adsorbent for CR removal from aqueous solutions, and it is easily recycled owing to its large specific surface area and unique magnetic responsiveness. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar® fiber

NASA Astrophysics Data System (ADS)

Pang, Hongwei; Bai, Ruicheng; Shao, Qinsi; Gao, Yufang; Li, Aijun; Tang, Zhiyong

2015-12-01

A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

Enzymatic detection of As(III) in aqueous solution using alginate immobilized pumpkin urease: optimization of process variables by response surface methodology.

PubMed

Talat, Mahe; Prakash, Om; Hasan, S H

2009-10-01

Urease immobilized on alginate was utilized to detect and quantify As(3+) in aqueous solution. Urease from the seeds of pumpkin (vegetable waste) was purified to apparent homogeneity by heat treatment and gel filtration (Sephadex G-200). Further enzyme was entrapped in 3.5% alginate beads. Urea hydrolysis by enzyme revealed a clear dependence on the concentration and interaction time of As(3+). The process variables effecting the quantitation of As(3+) was investigated using central composite design with Minitab 15 software. The predicted results were found in good agreement (R(2)=96.71%) with experimental results indicating the applicability of proposed model. The multiple regression analysis and ANOVA showed that enzyme activity decreased with increase of As(3+) concentration and interaction time. 3D plot and contour plot between As(3+) concentration and interaction time was helpful to predict residual activity of enzyme for a particular As(3+) at a particular time.

Homogeneous photocatalytic oxidation of UV filter para-aminobenzoic acid in aqueous solutions.

PubMed

Tsoumachidou, Sophia; Lambropoulou, Dimitra; Poulios, Ioannis

2017-01-01

The presence of personal care product (PCP) residues in the aquatic environment is an emerging issue due to their uncontrolled release through graywater; for this reason, efforts are being made to develop methods to inactivate or eliminate this class of substances in the environment. In this work, homogeneous photocatalysis has been applied for the degradation of UV filter para-aminobenzoic acid (PABA), which exists in several types of PCPs, in order to identify the optimum degradation conditions. The oxidation of PABA by photo-Fenton and oxalate-induced photo-Fenton (ferrioxalate) processes was investigated, and the effect of various operating variables has been assessed, i.e., Fe 3+ (0.0035-0.014 g L -1 ), H 2 O 2 (0.025-0.2 g L -1 ), T (280-323 K), and type of radiation (UV-A, visible). Furthermore, experiments under optimal conditions have been performed in order to evaluate the transformation pathways and phytotoxicity of the treated PABA solution.

Prediction of ice content in biological model solutions when frozen under high pressure.

PubMed

Guignon, B; Aparicio, C; Otero, L; Sanz, P D

2009-01-01

High pressure is, at least, as effective as cryoprotective agents (CPAs) and are used for decreasing both homogenous nucleation and freezing temperatures. This fact gives rise to a great variety of possible cryopreservation processes under high pressure. They have not been optimized yet, since they are relatively recent and are mainly based on the pressure-temperature phase diagram of pure water. Very few phase diagrams of biological material are available under pressure. This is owing to the lack of suitable equipment and to the difficulties encountered in carrying out the measurements. Different aqueous solutions of salt and CPAs as biological models are studied in the range of 0 degrees C down to -35 degrees C, 0.1 up to 250 MPa, and 0-20% w/w total solute concentration. The phase transition curves of glycerol and of sodium chloride with either glycerol or sucrose in aqueous solutions are determined in a high hydrostatic pressure vessel. The experimental phase diagrams of binary solutions were well described by a third-degree polynomial equation. It was also shown that Robinson and Stokes' equation at high pressure succeeds in predicting the phase diagrams of both binary and ternary solutions. The solute cryoconcentration and the ice content were calculated as a function of temperature and pressure conditions during the freezing of a binary solution. This information should provide a basis upon which high-pressure cryopreservation processes may be performed and the damages derived from ice formation evaluated. (c) 2009 American Institute of Chemical Engineers Biotechnol.

Facile method for preparing organic/inorganic hybrid capsules using amino-functional silane coupling agent in aqueous media.

PubMed

Kurayama, Fumio; Suzuki, Satoru; Oyamada, Tetsuro; Furusawa, Takeshi; Sato, Masahide; Suzuki, Noboru

2010-09-01

A new and facile method for preparing microcapsules with 3-aminopropyltriethoxysilane (APTES)/alginate hybrid shell (AP-capsule) is proposed based on gelling and sol-gel processes. In this method, conventional capsules with alginate shells (Alg-capsule) are produced by dripping carboxymethyl cellulose solution containing calcium chloride into a sodium alginate solution. Subsequently, addition of the Alg-capsules to an aqueous APTES solution induces the formation of APTES/alginate hybrid shells. The optical observation shows that the texture of AP-capsules is more glossy and transparent than that of Alg-capsules. The surface morphology and elemental composition of microcapsules were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). The results suggest that APTES molecules are incorporated to the framework of the alginate shells via electrostatic interaction between amino groups of APTES and carboxyl groups of alginate and the hybrid shells have a dense and homogeneous structure. In the formation reaction, the shrinking of the capsule shells occurs and the accumulation of APTES in the capsule shells proceeds with pseudo first-order kinetics. Moreover, these behaviors are greatly influenced by pH of the reaction solution, especially promoted under acidic and alkaline conditions. Copyright 2010 Elsevier Inc. All rights reserved.

Zirconium doped nano-dispersed oxides of Fe, Al and Zn for destruction of warfare agents

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

Stengl, Vaclav, E-mail: stengl@uach.cz; Houskova, Vendula; Bakardjieva, Snejana

2010-11-15

Zirconium doped nano dispersive oxides of Fe, Al and Zn were prepared by a homogeneous hydrolysis of the respective sulfate salts with urea in aqueous solutions. Synthesized metal oxide hydroxides were characterized using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). These oxides were taken for an experimental evaluation of their reactivity with sulfur mustard (HD or bis(2-chloroethyl)sulfide), soman (GD or (3,3'-Dimethylbutan-2-yl)-methylphosphonofluoridate) and VX agent (S-[2-(diisopropylamino)ethyl]-O-ethyl-methylphosphonothionate). The presence of Zr{sup 4+} dopant can increase both the surface area and the surface hydroxylation of the resultingmore » doped oxides, decreases their crystallites' sizes thereby it may contribute in enabling the substrate adsorption at the oxide surface thus it can accelerate the rate of degradation of warfare agents. Addition of Zr{sup 4+} converts the product of the reaction of ferric sulphate with urea from ferrihydrite to goethite. We found out that doped oxo-hydroxides Zr-FeO(OH) - being prepared by a homogeneous hydrolysis of ferric and zirconium oxo-sulfates mixture in aqueous solutions - exhibit a comparatively higher degradation activity towards chemical warfare agents (CWAs). Degradation of soman or VX agent on Zr-doped FeO(OH) containing ca. 8.3 wt.% of zirconium proceeded to completion within 30 min.« less

Solvent exchange method: a novel microencapsulation technique using dual microdispensers.

PubMed

Yeo, Yoon; Chen, Alvin U; Basaran, Osman A; Park, Kinam

2004-08-01

A new microencapsulation method called the "solvent exchange method" was developed using a dual microdispenser system. The objective of this research is to demonstrate the new method and understand how the microcapsule size is controlled by different instrumental parameters. The solvent exchange method was carried out using a dual microdispenser system consisting of two ink-jet nozzles. Reservoir-type microcapsules were generated by collision of microdrops of an aqueous and a polymer solution and subsequent formation of polymer films at the interface between the two solutions. The prepared microcapsules were characterized by microscopic methods. The ink-jet nozzles produced drops of different sizes with high accuracy according to orifice size of a nozzle, flow rate of the jetted solutions, and forcing frequency of the piezoelectric transducers. In an individual microcapsule, an aqueous core was surrounded by a thin polymer membrane; thus, the size of the collected microcapsules was equivalent to that of single drops. The solvent exchange method based on a dual microdispenser system produces reservoir-type microcapsules in a homogeneous and predictable manner. Given the unique geometry of the microcapsules and mildness of the encapsulation process, this method is expected to provide a useful alternative to existing techniques in protein microencapsulation.

Preferential binding effects on protein structure and dynamics revealed by coarse-grained Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Pandey, R. B.; Jacobs, D. J.; Farmer, B. L.

2017-05-01

The effect of preferential binding of solute molecules within an aqueous solution on the structure and dynamics of the histone H3.1 protein is examined by a coarse-grained Monte Carlo simulation. The knowledge-based residue-residue and hydropathy-index-based residue-solvent interactions are used as input to analyze a number of local and global physical quantities as a function of the residue-solvent interaction strength (f). Results from simulations that treat the aqueous solution as a homogeneous effective solvent medium are compared to when positional fluctuations of the solute molecules are explicitly considered. While the radius of gyration (Rg) of the protein exhibits a non-monotonic dependence on solvent interaction over a wide range of f within an effective medium, an abrupt collapse in Rg occurs in a narrow range of f when solute molecules rapidly bind to a preferential set of sites on the protein. The structure factor S(q) of the protein with wave vector (q) becomes oscillatory in the collapsed state, which reflects segmental correlations caused by spatial fluctuations in solute-protein binding. Spatial fluctuations in solute binding also modify the effective dimension (D) of the protein in fibrous (D ˜ 1.3), random-coil (D ˜ 1.75), and globular (D ˜ 3) conformational ensembles as the interaction strength increases, which differ from an effective medium with respect to the magnitude of D and the length scale.

Recovery of acetic acid from dilute aqueous solutions using catalytic dehydrative esterification with ethanol.

PubMed

Yagyu, Daisuke; Ohishi, Tetsuo; Igarashi, Takeshi; Okumura, Yoshikuni; Nakajo, Tetsuo; Mori, Yuichiro; Kobayashi, Shū

2013-03-01

We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system. Copyright © 2012 Elsevier Ltd. All rights reserved.

Combined Homogeneous Surface Diffusion Model - Design of experiments approach to optimize dye adsorption considering both equilibrium and kinetic aspects.

PubMed

Muthukkumaran, A; Aravamudan, K

2017-12-15

Adsorption, a popular technique for removing azo dyes from aqueous streams, is influenced by several factors such as pH, initial dye concentration, temperature and adsorbent dosage. Any strategy that seeks to identify optimal conditions involving these factors, should take into account both kinetic and equilibrium aspects since they influence rate and extent of removal by adsorption. Hence rigorous kinetics and accurate equilibrium models are required. In this work, the experimental investigations pertaining to adsorption of acid orange 10 dye (AO10) on activated carbon were carried out using Central Composite Design (CCD) strategy. The significant factors that affected adsorption were identified to be solution temperature, solution pH, adsorbent dosage and initial solution concentration. Thermodynamic analysis showed the endothermic nature of the dye adsorption process. The kinetics of adsorption has been rigorously modeled using the Homogeneous Surface Diffusion Model (HSDM) after incorporating the non-linear Freundlich adsorption isotherm. Optimization was performed for kinetic parameters (color removal time and surface diffusion coefficient) as well as the equilibrium affected response viz. percentage removal. Finally, the optimum conditions predicted were experimentally validated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue

USGS Publications Warehouse

Idowu, O.R.; Kijak, P.J.; Meinertz, J.R.; Schmidt, L.J.

2004-01-01

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb.

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue.

PubMed

Idowu, Olutosin R; Kijak, Philip J; Meinertz, Jeffery R; Schmidt, Larry J

2004-01-01

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb.

Evaluating the potential for quantitative monitoring of in situ chemical oxidation of aqueous-phase TCE using in-phase and quadrature electrical conductivity

NASA Astrophysics Data System (ADS)

Hort, R. D.; Revil, A.; Munakata-Marr, J.; Mao, D.

2015-07-01

Electrical resistivity measurements can potentially be used to remotely monitor fate and transport of ionic oxidants such as permanganate (MnO4-) during in situ chemical oxidation (ISCO) of contaminants like trichloroethene (TCE). Time-lapse two-dimensional bulk conductivity and induced polarization surveys conducted during a sand tank ISCO simulation demonstrated that MnO4- plume movement could be monitored in a qualitative manner using bulk conductivity tomograms, although chargeability was below sensitivity limits. We also examined changes to in-phase and quadrature electrical conductivity resulting from ion injection, MnO2 and Cl- production, and pH change during TCE and humate oxidation by MnO4- in homogeneous aqueous solutions and saturated porous media samples. Data from the homogeneous samples demonstrated that inversion of the sand tank resistivity data using a common Tikhonov regularization approach was insufficient to recover an accurate conductivity distribution within the tank. While changes to in-phase conductivity could be successfully modeled, quadrature conductivity values could not be directly related to TCE oxidation product or MnO4- concentrations at frequencies consistent with field induced polarization surveys, limiting the utility of quadrature conductivity for monitoring ISCO.

A facile synthesis of mesoporous Pdsbnd ZnO nanocomposites as efficient chemical sensor

NASA Astrophysics Data System (ADS)

Ismail, Adel A.; Harraz, Farid A.; Faisal, M.; El-Toni, Ahmed Mohamed; Al-Hajry, A.; Al-Assiri, M. S.

2016-07-01

Mesoporous ZnO was synthesized through the sol-gel method in the presence of triblock co-polymer Pluronic (F-127) template as the structure directing agent. Palladium nanoparticles were photochemically reduced and deposited onto mesoporous ZnO to obtain 1 wt.% Pd/ZnO nanocomposite. Structural and morphological analysis revealed high homogeneity and monodispersity of Pd nanoclusters with small particle sizes ∼ 2-5 nm onto mesoporous ZnO. The electrochemical detection of ethanol in aqueous solutions was conducted at the newly developed Pd/ZnO modified glassy carbon electrode (GCE) by the current-potential (IV) and cyclic voltammetry (CV) techniques and compared with bare GCE or pure ZnO. The presence of Pd dopant greatly enhances the sensitivity of ZnO, and the obtained mesoporous Pd/ZnO sensor has an excellent performance for precision detection of ethanol in aqueous solution with low concentration. The sensitivity was found to be 33.08 μAcm-2 mM-1 at lower concentration zone (0.05-0.8 mM) and 2.13 μAcm-2 mM-1 at higher concentration zone (0.8-12 mM), with a limit of detection (LOD) 19.2 μM. The kinetics study of ethanol oxidation revealed a characteristic feature for a mixed surface and diffusion-controlled process. These excellent sensing characteristics make the mesoporous Pd/ZnO nanocomposite a good candidate for the production of high-performance electrochemical sensors at low ethanol concentration in aqueous solution.

Tannin-immobilized cellulose hydrogel fabricated by a homogeneous reaction as a potential adsorbent for removing cationic organic dye from aqueous solution.

PubMed

Pei, Ying; Chu, Shan; Chen, Yue; Li, Zhidong; Zhao, Jin; Liu, Shuqi; Wu, Xingjun; Liu, Jie; Zheng, Xuejing; Tang, Keyong

2017-10-01

Tannin-immobilized cellulose (CT) hydrogels were successfully fabricated by homogeneous immobilization and crosslinking reaction via a simple method. The structures and properties of hydrogels were characterized by SEM and mechanical test. Methlyene Blue (MB) was selected as a cationic dye model, and the adsorption ability of CT hydrogel was evaluated. Tannins immobilized acted as adsorbent sites which combined MB by electrostatic attraction, resulting in the attractive adsorption ability of CT hydrogel. Adsorption kinetics could be better described by the pseudo-second-order model, and the absorption behaviors were in agreement with a Langmuir isotherm. The adsorption-desorption cycle of CT hydrogel was repeated six times without significant loss of adsorption capacity. In this work, both tannin immobilization and hydrogel formation were achieved simultaneously by a facile homogeneous reaction, providing a new pathway to fabricate tannin-immobilized materials for water treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Cd(1-x)Zn(x)O [0.05 ≤x≤ 0.26] synthesized by vapor-diffusion induced hydrolysis and co-nucleation from aqueous metal salt solutions.

PubMed

Schwenzer, Birgit; Neilson, James R; Jeffries, Stacie M; Morse, Daniel E

2011-02-14

Nanoparticulate Cd(1-x)Zn(x)O (x = 0, 0.05-0.26, 1) is synthesized in a simple two-step synthesis approach. Vapor-diffusion induced catalytic hydrolysis of two molecular precursors at low temperature induces co-nucleation and polycondensation to produce bimetallic layered hydroxide salts (M = Cd, Zn) as precursor materials which are subsequently converted to Cd(1-x)Zn(x)O at 400 °C. Unlike ternary materials prepared by standard co-precipitation procedures, all products presented here containing < 30 mol% Zn(2+) ions are homogeneous in elemental composition on the micrometre scale. This measured compositional homogeneity within the samples, as determined by energy dispersive spectroscopy and inductively coupled plasma spectroscopy, is a testimony to the kinetic control achieved by employing slow hydrolysis conditions. In agreement with this observation, the optical properties of the materials obey Vegard's Law for a homogeneous solid solution of Cd(1-x)Zn(x)O, where x corresponds to the values determined by inductively coupled plasma analysis, even though powder X-ray diffraction shows phase separation into a cubic mixed metal oxide phase and a hexagonal ZnO phase at all doping levels.

Adsorption of basic dyes on granular activated carbon and natural zeolite.

PubMed

Meshko, V; Markovska, L; Mincheva, M; Rodrigues, A E

2001-10-01

The adsorption of basic dyes from aqueous solution onto granular activated carbon and natural zeolite has been studied using an agitated batch adsorber. The influence of agitation, initial dye concentration and adsorbent mass has been studied. The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Homogeneous diffusion model (solid diffusion) combined with external mass transfer resistance is proposed for the kinetic investigation. The dependence of solid diffusion coefficient on initial concentration and mass adsorbent is represented by the simple empirical equations.

Gas-liquid chromatographic determination of 3-trifluoromethyl-4-nitrophenol residues in fish

USGS Publications Warehouse

Allen, J.L.; Sills, J.B.

1974-01-01

A procedure for the determination of 3-mftuormethyl-4-nitrophenol (TFM) in fish tissues is described. Homogenized tissues are extracted with hexane-ethyl ether; the extract is cleaned up by partitioning the TFM from the extracting solvent into O.IN NaOB, acidifying the aqueous solution, and partitioning again with hexaneethyl ether. The TFM is methylated with diazomethane and analyzed by gas-liquid chromatography, using electron capture detection. Recoveries ranged from 75 to 1000/., from fish muscles that were spiked with 0.01-2.00 JA#g TFM/g.

Mechanisms and Rates of U(VI) Reduction by Fe(II) in Homogeneous Aqueous Solution and the Role of U(V) Disproportionation

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

Collins, Richard N.; Rosso, Kevin M.

Molecular-level pathways in the aqueous redox transformation of uranium by iron remain unclear, despite the importance of this knowledge for predicting uranium transport and distribution in natural and engineered environments. As the relative importance of homogeneous versus heterogeneous pathways is difficult to probe experimentally, here we apply computational molecular simulation to isolate rates of key one electron transfer reactions in the homogeneous pathway. By comparison to experimental observations the role of the heterogeneous pathway also becomes clear. Density functional theory (DFT) and Marcus theory calculations for all primary monomeric species at pH values ≤7 show for UO22+ and its hydrolysismore » species UO2OH+ and UO2(OH)20 that reduction by Fe2+ is thermodynamically favorable, though kinetically limited for UO22+. An inner-sphere encounter complex between UO2OH+ and Fe2+ was the most stable for the first hydrolysis species and displayed an electron transfer rate constant ket = 4.3 × 103 s-1. Three stable inner- and outer-sphere encounter complexes between UO2(OH)20 and Fe2+ were found, with electron transfer rate constants ranging from ket = 7.6 × 102 to 7.2 × 104 s-1. Homogeneous reduction of these U(VI) hydrolysis species to U(V) is, therefore, predicted to be facile. In contrast, homogeneous reduction of UO2+ by Fe2+ was found to be thermodynamically unfavorable, suggesting the possible importance of U(V)-U(V) disproportionation as a route to U(IV). Calculations on homogeneous disproportionation, however, while yielding a stable outer-sphere U(V)-U(V) encounter complex, indicate that this electron transfer reaction is not feasible at circumneutral pH. Protonation of both axial O atoms of acceptor U(V) (i.e., by H3O+) was found to be a prerequisite to stabilize U(IV), consistent with the experimental observation that the rate of this reaction is inversely correlated with pH. Thus, despite prevailing notions that U(V) is rapidly eliminated by homogeneous disproportionation, this pathway is irrelevant at environmental conditions.« less

Aqueous carbon black dispersions prepared with steam jet-cooked corn starch

USDA-ARS?s Scientific Manuscript database

The utilization of jet-cooked waxy and normal corn starch to prepare aqueous dispersions of hydrophobic carbon black (Vulcan XC-72R) is reported. Blending carbon black (CB) into aqueous jet-cooked dispersions of starch followed by high pressure homogenization produced stable aqueous carbon black di...

Preparation of electrochromic thin films by transformation of manganese(II) carbonate

NASA Astrophysics Data System (ADS)

Stojkovikj, Sasho; Najdoski, Metodija; Koleva, Violeta; Demiri, Sani

2013-10-01

A new chemical bath method for deposition of manganese(II) carbonate thin film on electroconductive FTO glass substrates is designed. The homogeneous thin films with thickness in the range of 70 to 500 nm are deposited at about 98 °C from aqueous solution containing urea and MnCl2. The chemical process is based on a low temperature hydrolysis of the manganese complexes with urea. Three types of films are under consideration: as-deposited, annealed and electrochemically transformed thin films. The structure of the films is studied by XRD, IR and Raman spectroscopy. Electrochemical and optical properties are examined in eight different electrolytes (neutral and alkaline) and the best results are achieved in two component aqueous solution of 0.1 M KNO3 and 0.01 M KOH. It is established that the as-deposited MnCO3 film undergoes electrochemically transformation into birnessite-type manganese(IV) oxide films, which exhibit electrochromic color changes (from bright brown to pale yellow and vice versa) with 30% difference in the transmittance of the colored and bleached state at 400 nm.

A Review of Multidimensional, Multifluid Intermediate-scale Experiments: Flow Behavior, Saturation Imaging, and Tracer Detection and Quantification

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

Oostrom, Mart; Dane, J. H.; Wietsma, Thomas W.

2007-08-01

A review is presented of original multidimensional, intermediate-scale experiments involving non-aqueous phase liquid (NAPL) flow behavior, imaging, and detection/quantification with solute tracers. In a companion paper (Oostrom, M., J.H. Dane, and T.W. Wietsma. 2006. A review of multidimensional, multifluid intermediate-scale experiments: Nonaqueous phase dissolution and enhanced remediation. Vadose Zone Journal 5:570-598) experiments related to aqueous dissolution and enhanced remediation were discussed. The experiments investigating flow behavior include infiltration and redistribution experiments with both light and dense NAPLs in homogeneous and heterogeneous porous medium systems. The techniques used for NAPL saturation mapping for intermediate-scale experiments include photon-attenuation methods such as gammamore » and X-ray techniques, and photographic methods such as the light reflection, light transmission, and multispectral image analysis techniques. Solute tracer methods used for detection and quantification of NAPL in the subsurface are primarily limited to variations of techniques comparing the behavior of conservative and partitioning tracers. Besides a discussion of the experimental efforts, recommendations for future research at this laboratory scale are provided.« less

The effect of pH and triethanolamine on sulfisoxazole complexation with hydroxypropyl-beta-cyclodextrin.

PubMed

Gladys, Granero; Claudia, Garnero; Marcela, Longhi

2003-11-01

A novel complexation of sulfisoxazole with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was studied. Two systems were used: binary complexes prepared with HP-beta-CD and multicomponent system (HP-beta-CD and the basic compound triethanolamine (TEA)). Inclusion complex formation in aqueous solutions and in solid state were investigated by the solubility method, thermal analysis (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)), Fourier-transform infrared spectroscopy (FT-IR) and dissolution studies. The solid complexes of sulfisoxazole were prepared by freeze-drying the homogeneous concentrated aqueous solutions in molar ratios of sulfisoxazole:HP-beta-CD 1:1 and 1:2, and sulfisoxazole:TEA:HP-beta-CD 1:1:2. FT-IR and thermal analysis showed differences among sulfisoxazole:HP-beta-CD and sulfisoxazole:TEA:HP-beta-CD and their corresponding physical mixtures and individual components. The HP-beta-CD solubilization of sulfisoxazole could be improved by ionization of the drug molecule through pH adjustments. However, larger improvements of the HP-beta-CD solubilization are obtained when multicomponent systems are used, allowing to reduce the amount of CD necessary to prepare the target formulation.

Metabolic Compartmentation – A System Level Property of Muscle Cells

PubMed Central

Saks, Valdur; Beraud, Nathalie; Wallimann, Theo

2008-01-01

Problems of quantitative investigation of intracellular diffusion and compartmentation of metabolites are analyzed. Principal controversies in recently published analyses of these problems for the living cells are discussed. It is shown that the formal theoretical analysis of diffusion of metabolites based on Fick's equation and using fixed diffusion coefficients for diluted homogenous aqueous solutions, but applied for biological systems in vivo without any comparison with experimental results, may lead to misleading conclusions, which are contradictory to most biological observations. However, if the same theoretical methods are used for analysis of actual experimental data, the apparent diffusion constants obtained are orders of magnitude lower than those in diluted aqueous solutions. Thus, it can be concluded that local restrictions of diffusion of metabolites in a cell are a system-level properties caused by complex structural organization of the cells, macromolecular crowding, cytoskeletal networks and organization of metabolic pathways into multienzyme complexes and metabolons. This results in microcompartmentation of metabolites, their channeling between enzymes and in modular organization of cellular metabolic networks. The perspectives of further studies of these complex intracellular interactions in the framework of Systems Biology are discussed. PMID:19325782

A simulation study of homogeneous ice nucleation in supercooled salty water

NASA Astrophysics Data System (ADS)

Soria, Guiomar D.; Espinosa, Jorge R.; Ramirez, Jorge; Valeriani, Chantal; Vega, Carlos; Sanz, Eduardo

2018-06-01

We use computer simulations to investigate the effect of salt on homogeneous ice nucleation. The melting point of the employed solution model was obtained both by direct coexistence simulations and by thermodynamic integration from previous calculations of the water chemical potential. Using a seeding approach, in which we simulate ice seeds embedded in a supercooled aqueous solution, we compute the nucleation rate as a function of temperature for a 1.85 NaCl mol per water kilogram solution at 1 bar. To improve the accuracy and reliability of our calculations, we combine seeding with the direct computation of the ice-solution interfacial free energy at coexistence using the Mold Integration method. We compare the results with previous simulation work on pure water to understand the effect caused by the solute. The model captures the experimental trend that the nucleation rate at a given supercooling decreases when adding salt. Despite the fact that the thermodynamic driving force for ice nucleation is higher for salty water for a given supercooling, the nucleation rate slows down with salt due to a significant increase of the ice-fluid interfacial free energy. The salty water model predicts an ice nucleation rate that is in good agreement with experimental measurements, bringing confidence in the predictive ability of the model. We expect that the combination of state-of-the-art simulation methods here employed to study ice nucleation from solution will be of much use in forthcoming numerical investigations of crystallization in mixtures.

A simulation study of homogeneous ice nucleation in supercooled salty water.

PubMed

Soria, Guiomar D; Espinosa, Jorge R; Ramirez, Jorge; Valeriani, Chantal; Vega, Carlos; Sanz, Eduardo

2018-06-14

We use computer simulations to investigate the effect of salt on homogeneous ice nucleation. The melting point of the employed solution model was obtained both by direct coexistence simulations and by thermodynamic integration from previous calculations of the water chemical potential. Using a seeding approach, in which we simulate ice seeds embedded in a supercooled aqueous solution, we compute the nucleation rate as a function of temperature for a 1.85 NaCl mol per water kilogram solution at 1 bar. To improve the accuracy and reliability of our calculations, we combine seeding with the direct computation of the ice-solution interfacial free energy at coexistence using the Mold Integration method. We compare the results with previous simulation work on pure water to understand the effect caused by the solute. The model captures the experimental trend that the nucleation rate at a given supercooling decreases when adding salt. Despite the fact that the thermodynamic driving force for ice nucleation is higher for salty water for a given supercooling, the nucleation rate slows down with salt due to a significant increase of the ice-fluid interfacial free energy. The salty water model predicts an ice nucleation rate that is in good agreement with experimental measurements, bringing confidence in the predictive ability of the model. We expect that the combination of state-of-the-art simulation methods here employed to study ice nucleation from solution will be of much use in forthcoming numerical investigations of crystallization in mixtures.

ISOLATION OF SKELETAL MUSCLE NUCLEI

PubMed Central

Edelman, Jean C.; Edelman, P. Michael; Knigge, Karl M.; Schwartz, Irving L.

1965-01-01

A method employing aqueous media for isolation of nuclei from rat skeletal muscle is described. The technique involves (a) mincing and then homogenizing in a 0.32 M sucrose-salt solution with a Potter-Elvehjem type homogenizer using a Delrin (an acetal resin) pestle and a carefully controlled, relatively large pestle-to-glass clearance, (b) filtering through fiberglass and stainless steel screens of predetermined mesh size to remove myofibrils and connective tissue, and (c) centrifuging in a 2.15 M sucrose-salt solution containing 0.7 mM ATP. Electron and phase-contrast microscopic observations show that the nuclei are intact, unencumbered by cytoplasmic tags, and possess well preserved distinct nucleoli, nucleoplasm, and nuclear membranes. Cytoplasmic contamination is minimal and mainly mitochondrial. Chemical assays of the nuclear fraction show that the DNA/protein and RNA/DNA ratios are comparable to those obtained in other tissues. These ratios, as well as the low specific activity obtained for cytochrome c oxidase and the virtual absence of myofibrillar ATPase, indicate a high degree of purity with minimal mitochondrial and myofibrillar contamination. The steps comprising the technique and the reasons for their selection are discussed. PMID:4287141

Solidification and microstructures of binary ice-I/hydrate eutectic aggregates

USGS Publications Warehouse

McCarthy, C.; Cooper, R.F.; Kirby, S.H.; Rieck, K.D.; Stern, L.A.

2007-01-01

The microstructures of two-phase binary aggregates of ice-I + salt-hydrate, prepared by eutectic solidification, have been characterized by cryogenic scanning electron microscopy (CSEM). The specific binary systems studied were H2O-Na2SO4, H2O-MgSO4, H2O-NaCl, and H2O-H2SO4; these were selected based on their potential application to the study of tectonics on the Jovian moon Europa. Homogeneous liquid solutions of eutectic compositions were undercooled modestly (??T - 1-5 ??C); similarly cooled crystalline seeds of the same composition were added to circumvent the thermodynamic barrier to nucleation and to control eutectic growth under (approximately) isothermal conditions. CSEM revealed classic eutectic solidification microstructures with the hydrate phase forming continuous lamellae, discontinuous lamellae, or forming the matrix around rods of ice-I, depending on the volume fractions of the phases and their entropy of dissolving and forming a homogeneous aqueous solution. We quantify aspects of the solidification behavior and microstructures for each system and, with these data articulate anticipated effects of the microstructure on the mechanical responses of the materials.

Efficient production of ultrapure manganese oxides via electrodeposition.

PubMed

Cheney, Marcos A; Joo, Sang Woo; Banerjee, Arghya; Min, Bong-Ki

2012-08-01

A new process for the production of electrolytic amorphous nanomanganese oxides (EAMD) with uniform size and morphology is described. EAMD are produced for the first time by cathodic deposition from a basic aqueous solution of potassium permanganate at a constant temperature of 16°C. The synthesized materials are characterized by XRD, SEM, TEM, and HRTEM. The materials produced at 5.0 V at constant temperature are amorphous with homogeneous size and morphology with an average particle size around 20 nm, which appears to be much lesser than the previously reported anodic EAMD. A potentiostatic electrodeposition with much lesser deposition rate (with respect to previously reported anodic depositions) is considered to be the reason behind the very low and homogenous particle size distribution due to the lesser agglomeration of our as-synthesized nanoparticles. Copyright © 2012 Elsevier Inc. All rights reserved.

Aqueous electrolytes for redox flow battery systems

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

Liu, Tianbiao; Li, Bin; Wei, Xiaoliang

An aqueous redox flow battery system includes an aqueous catholyte and an aqueous anolyte. The aqueous catholyte may comprise (i) an optionally substituted thiourea or a nitroxyl radical compound and (ii) a catholyte aqueous supporting solution. The aqueous anolyte may comprise (i) metal cations or a viologen compound and (ii) an anolyte aqueous supporting solution. The catholyte aqueous supporting solution and the anolyte aqueous supporting solution independently may comprise (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.

The effects of ice on methane hydrate nucleation: a microcanonical molecular dynamics study.

PubMed

Zhang, Zhengcai; Guo, Guang-Jun

2017-07-26

Although ice powders are widely used in gas hydrate formation experiments, the effects of ice on hydrate nucleation and what happens in the quasi-liquid layer of ice are still not well understood. Here, we used high-precision constant energy molecular dynamics simulations to study methane hydrate nucleation from vapor-liquid mixtures exposed to the basal, prismatic, and secondary prismatic planes of hexagonal ice (ice Ih). Although no significant difference is observed in hydrate nucleation processes for these different crystal planes, it is found, more interestingly, that methane hydrate can nucleate either on the ice surface heterogeneously or in the bulk solution phase homogeneously. Several factors are mentioned to be able to promote the heterogeneous nucleation of hydrates, including the adsorption of methane molecules at the solid-liquid interface, hydrogen bonding between hydrate cages and the ice structure, the stronger ability of ice to transfer heat than that of the aqueous solution, and the higher occurrence probability of hydrate cages in the vicinity of the ice surface than in the bulk solution. Meanwhile, however, the other factors including the hydrophilicity of ice and the ice lattice mismatch with clathrate hydrates can inhibit heterogeneous nucleation on the ice surface and virtually promote homogeneous nucleation in the bulk solution. Certainly, the efficiency of ice as a promoter and as an inhibitor for heterogeneous nucleation is different. We estimate that the former is larger than the latter under the working conditions. Additionally, utilizing the benefit of ice to absorb heat, the NVE simulation of hydrate formation with ice can mimic the phenomenon of ice shrinking during the heterogeneous nucleation of hydrates and lower the overly large temperature increase during homogeneous nucleation. These results are helpful in understanding the nucleation mechanism of methane hydrate in the presence of ice.

Continuous manufacturing of solid lipid nanoparticles by hot melt extrusion.

PubMed

Patil, Hemlata; Kulkarni, Vijay; Majumdar, Soumyajit; Repka, Michael A

2014-08-25

Solid lipid nanoparticles (SLN) can either be produced by hot homogenization of melted lipids at higher temperatures or by a cold homogenization process. This paper proposes and demonstrates the formulation of SLN for pharmaceutical applications by combining two processes: hot melt extrusion (HME) technology for melt-emulsification and high-pressure homogenization (HPH) for size reduction. This work aimed at developing continuous and scalable processes for SLN by mixing a lipid and aqueous phase containing an emulsifier in the extruder barrel at temperatures above the melting point of the lipid and further reducing the particle size of emulsion by HPH linked to HME in a sequence. The developed novel platform demonstrated better process control and size reduction compared to the conventional process of hot homogenization (batch process). Varying the process parameters enabled the production of SLN below 200 nm (for 60 mg/ml lipid solution at a flow rate of 100ml/min). Among the several process parameters investigated, the lipid concentration, residence time and screw design played major roles in influencing the size of the SLN. This new process demonstrates the potential use of hot melt extrusion technology for continuous and large-scale production of SLN. Copyright © 2014 Elsevier B.V. All rights reserved.

Improvement of lindane removal by Streptomyces sp. M7 by using stable microemulsions.

PubMed

Saez, Juliana Maria; Casillas García, Verena; Benimeli, Claudia Susana

2017-10-01

Lindane is an organochlorine pesticide which persists in the environment and can cause serious health problems due to its chlorinated and hydrophobic nature. Microemulsions are isotropic and macroscopically homogeneous systems with high solubilization capacity of hydrophilic and hydrophobic compounds. The aim of this study was to evaluate the removal of high concentrations of lindane by the actinobacterium Streptomyces sp. M7 in aqueous and soil systems in the presence of stable microemulsions. Three stable microemulsions were successfully formed with Tween 80, 1-pentanol and three vegetable oils. In most cases, an increase in the cosurfactant/surfactant ratio in the microemulsions favored the solubilization of lindane, while an increase in the oil/surfactant ratio negatively affected the stability of the system. The microemulsion prepared with soybean oil allowed the solubilization of 66% of lindane added to the aqueous medium and 4.5 times more than the surfactant solution at the same concentration. This microemulsion increased the bioavailability of lindane in the aqueous medium and hence enhanced its removal by Streptomyces sp. M7 almost two times respect to the achieved with the surfactant solution. In loam soil system, the addition of the microemulsion allowed an 87% of lindane removal by Streptomyces sp. M7, increasing almost 50% the removal respect to the obtained without the addition of surfactant agents, although it did not present significant difference respect to the obtained with the surfactant solution. This is the first report on enhanced lindane removal by actinobacteria by using direct microemulsions as bioremediation tools. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental evidence for non-redox transformations between magnetite and hematite under H 2-rich hydrothermal conditions

NASA Astrophysics Data System (ADS)

Otake, Tsubasa; Wesolowski, David J.; Anovitz, Lawrence M.; Allard, Lawrence F.; Ohmoto, Hiroshi

2007-05-01

Transformations of magnetite (Fe IIFe 2IIIO 4) to hematite (Fe 2IIIO 3) (and vice versa) have been thought by many scientists and engineers to require molecular O 2 and/or H 2. Thus, the presence of magnetite and/or hematite in rocks has been linked to a specific oxidation environment. However, the availability of reductants or oxidants in many geologic and industrial environments appears to have been too low to account for the transformations of iron oxides through redox reactions. Here, we report the results of hydrothermal experiments in mildly acidic and H 2-rich aqueous solutions at 150 °C, which demonstrate that transformations of magnetite to hematite, and hematite to magnetite, occur rapidly without involving molecular O 2 or H 2: Fe3O 4(Mt) + 2H (aq)+ ↔ Fe 2O 3(Hm) + Fe (aq)2+ + H 2O. The transformation products are chemically and structurally homogeneous, and typically occur as euhedral single crystals much larger than the precursor minerals. This suggests that, in addition to the expected release of aqueous ferrous species to solution, the transformations involve release of aqueous ferric species from the precursor oxides to the solution, which reprecipitate without being reduced by H 2. These redox-independent transformations may have been responsible for the formation of some iron oxides in natural systems, such as high-grade hematite ores that developed from Banded Iron Formations (BIFs), hematite-rich deposits formed on Mars, corrosion products in power plants and other industrial systems.

Reduction of aqueous transition metal species on the surfaces of Fe(II)-containing oxides

USGS Publications Warehouse

White, A.F.; Peterson, M.L.

1996-01-01

Experimental studies demonstrate that structural Fe(II) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions at the oxide surfaces over a pH range of 1-7 at 25??C. For an aqueous transition metal m, such reactions are 3[Fe2+Fe3+2]O4(magnetite) + 2/nmz ??? 4[Fe3+2]O3(maghemite) + Fe2+ + 2/nmz-n and 3[Fe2+Ti]O3(ilmenite) + 2/nmz ??? Fe3+2Ti3O9(pseudorutile) + Fe2+ + 2/nmz-n, where z is the valance state and n is the charge transfer number. The half cell potential range for solid state oxidation [Fe(II)] ??? [Fe(III)] is -0.34 to -0.65 V, making structural Fe(II) a stronger reducing agent than aqueous Fe2+ (-0.77 V). Reduction rates for aqueous metal species are linear with time (up to 36 h), decrease with pH, and have rate constants between 0.1 and 3.3 ?? 10-10 mol m-2 s-1. Iron is released to solution both from the above reactions and from dissolution of the oxide surface. In the presence of chromate, Fe2+ is oxidized homogeneously in solution to Fe3+. X-ray photoelectron spectroscopy (XPS) denotes a Fe(III) oxide surface containing reduced Cr(III) and V(IV) species. Magnetite and ilmenite electrode potentials are insensitive to increases in divalent transition metals including Zn(II), Co(II), Mn(II), and Ni(II) and reduced V(IV) and Cr(III) but exhibit a log-linear concentration-potential response to Fe(III) and Cu(II). Complex positive electrode responses occur with increasing Cr(VI) and V(V) concentrations. Potential dynamic scans indicate that the high oxidation potential of dichromate is capable of suppressing the cathodic reductive dissolution of magnetite. Oxide electrode potentials are determined by the Fe(II)/Fe(III) composition of the oxide surface and respond to aqueous ion potentials which accelerate this oxidation process. Natural magnetite sands weathered under anoxic conditions are electrochemically reactive as demonstrated by rapid chromate reduction and the release of aqueous Fe(III) to experimental solution. In contrast, magnetite weathered under oxidizing vadose conditions show minimum reactivity toward chromate ions. The ability of Fe(II) oxides to reduce transition metals in soils and groundwaters will be strongly dependent on the redox environment.

Reduction of aqueous transition metal species on the surfaces of Fe(II) -containing oxides

NASA Astrophysics Data System (ADS)

White, Art F.; Peterson, Maria L.

1996-10-01

Experimental studies demonstrate that structural Fe(II) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions at the oxide surfaces over a pH range of 1-7 at 25°C. For an aqueous transition metal m, such reactions are 3[FeFe23+]O+2/nm→4[Fe23+]O+Fe+2/nm and 3[FeTi]O+→Fe23+TiO+Fe+2/nm, where z is the valance state and n is the charge transfer number. The half cell potential range for solid state oxidation [Fe(II)] → [Fe(III)] is -0.34 to -0.65 V, making structural Fe(II) a stronger reducing agent than aqueous Fe 2+ (-0.77 V). Reduction rates for aqueous metal species are linear with time (up to 36 h), decrease with pH, and have rate constants between 0.1 and 3.3 × 10 -10 mol m -2 s -1. Iron is released to solution both from the above reactions and from dissolution of the oxide surface. In the presence of chromate, Fe 2+ is oxidized homogeneously in solution to Fe 3+. X-ray photoelectron spectroscopy (XPS) denotes a Fe(III) oxide surface containing reduced Cr(III) and V(IV) species. Magnetite and ilmenite electrode potentials are insensitive to increases in divalent transition metals including Zn(II), Co(II), Mn(II), and Ni(II) and reduced V(IV) and Cr(III) but exhibit a log-linear concentration-potential response to Fe(III) and Cu(II). Complex positive electrode responses occur with increasing Cr(VI) and V(V) concentrations. Potential dynamic scans indicate that the high oxidation potential of dichromate is capable of suppressing the cathodic reductive dissolution of magnetite. Oxide electrode potentials are determined by the Fe(II)/Fe(III) composition of the oxide surface and respond to aqueous ion potentials which accelerate this oxidation process. Natural magnetite sands weathered under anoxic conditions are electrochemically reactive as demonstrated by rapid chromate reduction and the release of aqueous Fe(III) to experimental solution. In contrast, magnetite weathered under oxidizing vadose conditions show minimum reactivity toward chromate ions. The ability of Fe(II) oxides to reduce transition metals in soils and groundwaters will be strongly dependent on the redox environment.

Interpretation of the microwave effect on induction time during CaSO4 primary nucleation by a cluster coagulation model

NASA Astrophysics Data System (ADS)

Guo, Zhichao; Li, Liye; Han, Wenxiang; Li, Jiawei; Wang, Baodong; Xiao, Yongfeng

2017-10-01

The effects of microwave on the induction time of CaSO4 are studied experimentally and theoretically. In the experiments, calcium sulfate is precipitated by mixing aqueous CaCl2 solution and Na2SO4 solution. The induction time is measured by recording the change of turbidity in solution. Various energy inputs are used to investigate the effect of energy input on nucleation. The results show that the induction time decreases with increasing supersaturation and increasing energy input. Employing the classical nucleation theory, the interfacial tension is estimated. In addition, the microwave effects on nucleation order (n) and nucleation coefficient (kN) are also investigated, and the corresponding values of homogeneous nucleation are compared with the values of heterogeneous nucleation in the microwave field. A cluster coagulation model, which brings together the classic nucleation models and the theories describing the behavior of colloidal suspension, was applied to estimate the induction time under various energy inputs. It is found that when nucleation is prominently homogeneous, the microwave energy input does not change the number of monomers in dominating clusters. And when nucleation is prominently heterogeneous, although the dominating cluster size increases with supersaturation increasing, at the same supersaturation level, the dominating cluster size remains constant in the microwave field.

Copper-mediated homogeneous living radical polymerization of acrylamide with waxy potato starch-based macroinitiator.

PubMed

Fan, Yifei; Cao, Huatang; van Mastrigt, Frank; Pei, Yutao; Picchioni, Francesco

2018-07-15

Cu 0 -mediated living radical polymerization (Cu 0 -mediated LRP) was employed in this research for the synthesis of starch-g-polyacrylamide (St-g-PAM). The use of a controlled radical grafting technique is necessary, as compared to the traditional free-radical polymerization methods, in order to obtain a well-defined structure of the final product. This is in turn essential for studying the relationship between such structure and the end-properties. Waxy potato starch-based water-soluble macroinitiator was first synthesized by esterification with 2-bromopropionyl bromide in the mixture of dimethylacetamide and lithium chloride. With the obtained macroinitiator, St-g-PAM was homogeneously synthesized by aqueous Cu 0 -mediated LRP using CuBr/hexamethylated tris(2-aminoethyl)amine (Me 6 Tren) as catalyst. The successful synthesis of the macroinitiator and St-g-PAM was proved by NMR, FT-IR, SEM, XRD and TGA analysis. The molecular weight and polydispersity of PAM chains were analyzed by gel permeation chromatography (GPC) after hydrolyzing the starch backbone. Monomer conversion was monitored by gas chromatography (GC), on the basis of which the kinetics were determined. A preliminarily rheological study was performed on aqueous solutions of the prepared materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Simulator for SUPO, a Benchmark Aqueous Homogeneous Reactor (AHR)

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

Klein, Steven Karl; Determan, John C.

2015-10-14

A simulator has been developed for SUPO (Super Power) an aqueous homogeneous reactor (AHR) that operated at Los Alamos National Laboratory (LANL) from 1951 to 1974. During that period SUPO accumulated approximately 600,000 kWh of operation. It is considered the benchmark for steady-state operation of an AHR. The SUPO simulator was developed using the process that resulted in a simulator for an accelerator-driven subcritical system, which has been previously reported.

Controlling dispersion of graphene nanoplatelets in aqueous solution by ultrasonic technique

NASA Astrophysics Data System (ADS)

Wang, Baomin; Jiang, Ruishuang; Song, Wanzeng; Liu, Hui

2017-08-01

The homogenous graphene nanoplatelets (GNP) suspension had been prepared through ultrasonic exfoliation in the presence of methylcellulose (MC) as dispersant. The influence of different sonication times on dispersing of aqueous GNP suspension was monitored by UV-Vis absorbance, sedimentation test, optical microscope and transmission electron microscope (TEM). The study of UV-Vis absorbance verifies that the minimum sonication time to break the 0.1 g/L concentration of bundled GNPs is 20 min; furthermore, the GNP suspension achieved the best dispersion, when sonication time increased up to 80 min. From optical microscope images of GNPs, the agglomeration of GNPs was broken by enough sonication energy, and the distribution of GNPs particles became more uniform. The dispersing mechanism had been discussed and simulated by HRTEM image. The bundled GNPs were exfoliated by cavitation effect of ultrasonic irradiation, meanwhile, the dispersant adsorbed on the surface of GNPs prevented re-entanglement by forming steric hindrance.

Subsurface solute transport with one-, two-, and three-dimensional arbitrary shape sources

NASA Astrophysics Data System (ADS)

Chen, Kewei; Zhan, Hongbin; Zhou, Renjie

2016-07-01

Solutions with one-, two-, and three-dimensional arbitrary shape source geometries will be very helpful tools for investigating a variety of contaminant transport problems in the geological media. This study proposed a general method to develop new solutions for solute transport in a saturated, homogeneous aquifer (confined or unconfined) with a constant, unilateral groundwater flow velocity. Several typical source geometries, such as arbitrary line sources, vertical and horizontal patch sources, circular and volumetric sources, were considered. The sources can sit on the upper or lower aquifer boundary to simulate light non-aqueous-phase-liquids (LNAPLs) or dense non-aqueous-phase-liquids (DNAPLs), respectively, or can be located anywhere inside the aquifer. The developed new solutions were tested against previous benchmark solutions under special circumstances and were shown to be robust and accurate. Such solutions can also be used as a starting point for the inverse problem of source zone and source geometry identification in the future. The following findings can be obtained from analyzing the solutions. The source geometry, including shape and orientation, generally played an important role for the concentration profile through the entire transport process. When comparing the inclined line sources with the horizontal line sources, the concentration contours expanded considerably along the vertical direction, and shrank considerably along the groundwater flow direction. A planar source sitting on the upper aquifer boundary (such as a LNAPL pool) would lead to significantly different concentration profiles compared to a planar source positioned in a vertical plane perpendicular to the flow direction. For a volumetric source, its dimension along the groundwater flow direction became less important compared to its other two dimensions.

A Base-Resistant Metalloporphyrin Metal–Organic Framework for C–H Bond Halogenation

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

Lv, Xiu-Liang; Wang, Kecheng; Wang, Bin

A base-resistant porphyrin metal–organic framework (MOF), namely PCN-602 has been constructed with 12-connected [Ni 8(OH) 4(H 2O) 2Pz 12] (Pz = pyrazolate) cluster and a newly designed pyrazolate-based porphyrin ligand, 5,10,15,20-tetrakis(4-(pyrazolate-4-yl)phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F –, CO 3 2–, and PO 4 3– ions. Interestingly, the Mn 3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C–H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOFmore » was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.« less

A liquid-liquid transition in supercooled aqueous solution related to the HDA-LDA transition

NASA Astrophysics Data System (ADS)

Woutersen, Sander; Ensing, Bernd; Hilbers, Michiel; Zhao, Zuofeng; Angell, C. Austen

2018-03-01

Simulations and theory suggest that the thermodynamic anomalies of water may be related to a phase transition between two supercooled liquid states, but so far this phase transition has not been observed experimentally because of preemptive ice crystallization. We used calorimetry, infrared spectroscopy, and molecular dynamics simulations to investigate a water-rich hydrazinium trifluoroacetate solution in which the local hydrogen bond structure surrounding a water molecule resembles that in neat water at elevated pressure, but which does not crystallize upon cooling. Instead, this solution underwent a sharp, reversible phase transition between two homogeneous liquid states. The hydrogen-bond structures of these two states are similar to those established for high- and low-density amorphous (HDA and LDA) water. Such structural similarity supports theories that predict a similar sharp transition in pure water under pressure if ice crystallization could be suppressed.

System and method for the analysis of one or more compounds and/or species produced by a solution-based nuclear reactor

DOEpatents

Policke, Timothy A; Nygaard, Eric T

2014-05-06

The present invention relates generally to both a system and method for determining the composition of an off-gas from a solution nuclear reactor (e.g., an Aqueous Homogeneous Reactor (AHR)) and the composition of the fissioning solution from those measurements. In one embodiment, the present invention utilizes at least one quadrupole mass spectrometer (QMS) in a system and/or method designed to determine at least one or more of: (i) the rate of production of at least one gas and/or gas species from a nuclear reactor; (ii) the effect on pH by one or more nitrogen species; (iii) the rate of production of one or more fission gases; and/or (iv) the effect on pH of at least one gas and/or gas species other than one or more nitrogen species from a nuclear reactor.

SOLVENT EXTRACTION PROCESS

DOEpatents

Jonke, A.A.

1957-10-01

In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

Generalised syntheses of ordered mesoporous oxides: the atrane route

NASA Astrophysics Data System (ADS)

Cabrera, Saúl; El Haskouri, Jamal; Guillem, Carmen; Latorre, Julio; Beltrán-Porter, Aurelio; Beltrán-Porter, Daniel; Marcos, M. Dolores; Amorós *, Pedro

2000-06-01

A new simple and versatile technique to obtain mesoporous oxides is presented. While implying surfactant-assisted formation of mesostructured intermediates, the original chemical contribution of this approach lies in the use of atrane complexes as precursors. Without prejudice to their inherent unstability in aqueous solution, the atranes show a marked inertness towards hydrolysis. Bringing kinetic factors into play, it becomes possible to control the processes involved in the formation of the surfactant-inorganic phase composite micelles, which constitute the elemental building blocks of the mesostructures. Independent of the starting compositional complexity, both the mesostructured intermediates and the final mesoporous materials are chemically homogeneous. The final ordered mesoporous materials are thermally stable and show unimodal porosity, as well as homogeneous microstructure and texture. Examples of materials synthesised on account of the versatility of this new method, including siliceous, non siliceous and mixed oxides, are presented and discussed.

Marble protection: An inorganic electrokinetic approach

NASA Astrophysics Data System (ADS)

Meloni, Paola; Manca, Francesco; Carcangiu, Gianfranco

2013-05-01

The influence of an electric potential difference in an aqueous solution was studied as a method for depositing a calcium oxalate coating over a weathered carbonatic stone. Samples of weathered Carrara white marble were treated at 15 and 50 °C for 5 h in an electrokinetic cell, specifically conceived for this study, containing a solution of ammonium oxalate (4% by weight), and were subsequently characterised by scanning electron microscopy, X-ray diffractometry, thermogravimetric analysis and mercury intrusion porosimetry. The electrokinetic treatment proved to be a cost effective and time saving process, able to produce a thick and homogeneous calcium oxalate coating over the stone surface that improves its chemical and physical resistance in low pH environments, and is able to protect the stone from the by-products of urban pollution.

Versatile Photocatalytic Systems for H2 Generation in Water Based on an Efficient DuBois-Type Nickel Catalyst

PubMed Central

2013-01-01

The generation of renewable H2 through an efficient photochemical route requires photoinduced electron transfer (ET) from a light harvester to an efficient electrocatalyst in water. Here, we report on a molecular H2 evolution catalyst (NiP) with a DuBois-type [Ni(P2R′N2R″)2]2+ core (P2R′N2R″ = bis(1,5-R′-diphospha-3,7-R″-diazacyclooctane), which contains an outer coordination sphere with phosphonic acid groups. The latter functionality allows for good solubility in water and immobilization on metal oxide semiconductors. Electrochemical studies confirm that NiP is a highly active electrocatalyst in aqueous electrolyte solution (overpotential of approximately 200 mV at pH 4.5 with a Faradaic yield of 85 ± 4%). Photocatalytic experiments and investigations on the ET kinetics were carried out in combination with a phosphonated Ru(II) tris(bipyridine) dye (RuP) in homogeneous and heterogeneous environments. Time-resolved luminescence and transient absorption spectroscopy studies confirmed that directed ET from RuP to NiP occurs efficiently in all systems on the nano- to microsecond time scale, through three distinct routes: reductive quenching of RuP in solution or on the surface of ZrO2 (“on particle” system) or oxidative quenching of RuP when the compounds were immobilized on TiO2 (“through particle” system). Our studies show that NiP can be used in a purely aqueous solution and on a semiconductor surface with a high degree of versatility. A high TOF of 460 ± 60 h–1 with a TON of 723 ± 171 for photocatalytic H2 generation with a molecular Ni catalyst in water and a photon-to-H2 quantum yield of approximately 10% were achieved for the homogeneous system. PMID:24320740

On a relationship between molecular polarizability and partial molar volume in water.

PubMed

Ratkova, Ekaterina L; Fedorov, Maxim V

2011-12-28

We reveal a universal relationship between molecular polarizability (a single-molecule property) and partial molar volume in water that is an ensemble property characterizing solute-solvent systems. Since both of these quantities are of the key importance to describe solvation behavior of dissolved molecular species in aqueous solutions, the obtained relationship should have a high impact in chemistry, pharmaceutical, and life sciences as well as in environments. We demonstrated that the obtained relationship between the partial molar volume in water and the molecular polarizability has in general a non-homogeneous character. We performed a detailed analysis of this relationship on a set of ~200 organic molecules from various chemical classes and revealed its fine well-organized structure. We found that this structure strongly depends on the chemical nature of the solutes and can be rationalized in terms of specific solute-solvent interactions. Efficiency and universality of the proposed approach was demonstrated on an external test set containing several dozens of polyfunctional and druglike molecules.

PROCESS OF REMOVING PLUTONIUM VALUES FROM SOLUTION WITH GROUP IVB METAL PHOSPHO-SILICATE COMPOSITIONS

DOEpatents

Russell, E.R.; Adamson, A.W.; Schubert, J.; Boyd, G.E.

1957-10-29

A process for separating plutonium values from aqueous solutions which contain the plutonium in minute concentrations is described. These values can be removed from an aqueous solution by taking an aqueous solution containing a salt of zirconium, titanium, hafnium or thorium, adding an aqueous solution of silicate and phosphoric acid anions to the metal salt solution, and separating, washing and drying the precipitate which forms when the two solutions are mixed. The aqueous plutonium containing solution is then acidified and passed over the above described precipi-tate causing the plutonium values to be adsorbed by the precipitate.

A novel method for the production of core-shell microparticles by inverse gelation optimized with artificial intelligent tools.

PubMed

Rodríguez-Dorado, Rosalia; Landín, Mariana; Altai, Ayça; Russo, Paola; Aquino, Rita P; Del Gaudio, Pasquale

2018-03-01

Numerous studies have been focused on hydrophobic compounds encapsulation as oils. In fact, oils can provide numerous health benefits as synergic ingredient combined with other hydrophobic active ingredients. However, stable microparticles for pharmaceutical purposes are difficult to achieve when commonly techniques are used. In this work, sunflower oil was encapsulated in calcium-alginate capsules by prilling technique in co-axial configuration. Core-shell beads were produced by inverse gelation directly at the nozzle using a w/o emulsion containing aqueous calcium chloride solution in sunflower oil pumped through the inner nozzle while an aqueous alginate solution, coming out from the annular nozzle, produced the beads shell. To optimize process parameters artificial intelligence tools were proposed to optimize the numerous prilling process variables. Homogeneous and spherical microcapsules with narrow size distribution and a thin alginate shell were obtained when the parameters as w/o constituents, polymer concentrations, flow rates and frequency of vibration were optimized by two commercial software, FormRules® and INForm®, which implement neurofuzzy logic and Artificial Neural Networks together with genetic algorithms, respectively. This technique constitutes an innovative approach for hydrophobic compounds microencapsulation. Copyright © 2018 Elsevier B.V. All rights reserved.

Covalent Attachment of the Water-insoluble Ni(P Cy 2 N Phe 2 ) 2 Electrocatalyst to Electrodes Showing Reversible Catalysis in Aqueous Solution

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

Rodríguez-Maciá, Patricia; Priyadarshani, Nilusha; Dutta, Arnab

Hydrogenases are a diverse group of metalloenzymes which catalyze the reversible conversion between molecular hydrogen and protons at high rates. The catalytic activity of these enzymes does not require overpotential because their active site has been evolutionarily optimized to operate fast and efficiently. These enzymes have inspired the development of molecular catalysts, which have dramatically improved in efficiency in recent years, to the point that some synthetic catalysts even outperform hydrogenases under certain conditions. In this work, we use a reversible noble-metal-free homogeneous catalyst, the [Ni(PCy2NPhe2)2]2+ complex, and we covalently immobilize it on a functionalized highly oriented pyrolytic graphite “edge”more » (HOPGe) electrode surface. This catalyst is not water soluble, but once it is surface-confined on the electrode, it maintains its catalytic properties in aqueous solutions, showing reversibility for H2 oxidation/reduction. Immobilization of the [Ni(PCy2NPhe2)2]2+ complex onto a multi-walled carbon nanotubes coated electrode leads to even higher catalytic current densities and enhanced stability.« less

Kinetics of removal of carbon dioxide by aqueous solutions of N,N-diethylethanolamine and piperazine.

PubMed

Konduru, Prashanti B; Vaidya, Prakash D; Kenig, Eugeny Y

2010-03-15

N,N-Diethylethanolamine (DEEA) is a very promising absorbent for CO(2) removal from gaseous streams, as it can be prepared from renewable resources. Aqueous mixtures of DEEA and piperazine (PZ) are attractive for the enhancement of CO(2) capture, due to the high CO(2) loading capacity of DEEA and high reactivity of PZ. In the present work, for the first time, the equilibrium and kinetic characteristics of the CO(2) reaction with such mixtures were considered. Kinetic data were obtained experimentally, by using a stirred cell reactor. These data were interpreted using a homogeneous activation mechanism, by which the investigated reaction was considered as a reaction between CO(2) and DEEA in parallel with the reaction of CO(2) with PZ. It is found that, in the studied range of temperatures, 298-308 K, and overall amine concentrations, 2.1-2.5 kmol/m(3), this reaction system belongs to the fast pseudo-first-order reaction regime systems. The second-order rate constant for the CO0 reaction with PZ was determined from the absorption rate measurements in the activated DEEA solutions, and its value at 303 K was found to be 24,450 m(3)/(kmol s).

High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

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

Huang, Yuqing; Cai, Shuhui; Yang, Yu

2016-03-14

High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this methodmore » are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.« less

Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System

PubMed Central

Hoogerstraete, Tom Vander; Onghena, Bieke; Binnemans, Koen

2013-01-01

Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature. PMID:24169434

The WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) and application for ambient dust

NASA Astrophysics Data System (ADS)

Reicher, Naama; Segev, Lior; Rudich, Yinon

2018-01-01

The WeIzmann Supercooled Droplets Observation on Microarray (WISDOM) is a new setup for studying ice nucleation in an array of monodisperse droplets for atmospheric implications. WISDOM combines microfluidics techniques for droplets production and a cryo-optic stage for observation and characterization of freezing events of individual droplets. This setup is designed to explore heterogeneous ice nucleation in the immersion freezing mode, down to the homogeneous freezing of water (235 K) in various cooling rates (typically 0.1-10 K min-1). It can also be used for studying homogeneous freezing of aqueous solutions in colder temperatures. Frozen fraction, ice nucleation active surface site densities and freezing kinetics can be obtained from WISDOM measurements for hundreds of individual droplets in a single freezing experiment. Calibration experiments using eutectic solutions and previously studied materials are described. WISDOM also allows repeatable cycles of cooling and heating for the same array of droplets. This paper describes the WISDOM setup, its temperature calibration, validation experiments and measurement uncertainties. Finally, application of WISDOM to study the ice nucleating particle (INP) properties of size-selected ambient Saharan dust particles is presented.

Delivery of fullerene-containing complexes via microgel swelling and shear-induced release.

PubMed

Tarabukina, Elena; Zoolshoev, Zoolsho; Melenevskaya, Elena; Budtova, Tatiana

2010-01-15

The absorption and release of poly(vinylpyrrolidone)-fullerene C60 complexes (PVP/C60) from a model microgel is studied. A dry microgel based on a chemically cross-linked sodium polyacrylate was swollen in the aqueous solutions of complexes which were afterwards released under shear stress. First, gel swelling degree in static conditions in the excess of PVP/C60 solutions was studied: the degree of swelling decreases with the increase in PVP/C60 concentration. While pure PVP is homogeneously distributed between the gel and the surrounding solution, a slight concentration of complexes outside the gel was recorded. It was attributed to PVP/C60 hydrophobicity leading to the decrease in the thermodynamic quality of fullerene-containing solution being gel solvent. The release of PVP/C60 solutions induced by shear was studied with counter-rotating rheo-optical technique and compared with PVP solution release under the same conditions. The amount of solution released depends on polymer concentration and shear strain. Contrary to pure PVP solutions in which rate of release decreases with the increase in polymer concentration, PVP/C60 complexes are released faster when fullerene concentration inside the gel is higher.

Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: crystallization relative humidities and nucleation rates.

PubMed

Pant, Atul; Parsons, Matthew T; Bertram, Allan K

2006-07-20

Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2 degrees. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 (the relative humidity at which 50% of the droplets crystallize) ranges from about 41 to 51% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 microm. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 microm diameter) free of solid material is approximately 34.3% RH under atmospheric conditions.

Crystallization of aqueous inorganic-malonic acid particles: nucleation rates, dependence on size, and dependence on the ammonium-to-sulfate ratio.

PubMed

Parsons, Matthew T; Riffell, Jenna L; Bertram, Allan K

2006-07-06

Using an electrodynamic balance, we determined the relative humidity (RH) at which aqueous inorganic-malonic acid particles crystallized, with ammonium sulfate ((NH(4))(2)SO(4)), letovicite ((NH(4))(3)H(SO(4))(2)), or ammonium bisulfate (NH(4)HSO(4)) as the inorganic component. The results for (NH(4))(2)SO(4)-malonic acid particles and (NH(4))(3)H(SO(4))(2)-malonic acid particles show that malonic acid decreases the crystallization RH of the inorganic particles by less than 7% RH when the dry malonic acid mole fraction is less than 0.25. At a dry malonic acid mole fraction of about 0.5, the presence of malonic acid can decrease the crystallization RH of the inorganic particles by up to 35% RH. For the NH(4)HSO(4)-malonic acid particles, the presence of malonic acid does not significantly modify the crystallization RH of the inorganic particles for the entire range of dry malonic acid mole fractions studied; in all cases, either the particles did not crystallize or the crystallization RH was close to 0% RH. Size dependent measurements show that the crystallization RH of aqueous (NH(4))(2)SO(4) particles is not a strong function of particle volume. However, for aqueous (NH(4))(2)SO(4)-malonic acid particles (with dry malonic acid mole fraction = 0.36), the crystallization RH is a stronger function of particle volume, with the crystallization RH decreasing by 6 +/- 3% RH when the particle volume decreases by an order of magnitude. To our knowledge, these are the first size dependent measurements of the crystallization RH of atmospherically relevant inorganic-organic particles. These results suggest that for certain organic mole fractions the particle size and observation time need to be considered when extrapolating laboratory crystallization results to atmospheric scenarios. For aqueous (NH(4))(2)SO(4) particles, the homogeneous nucleation rate data are a strong function of RH, but for aqueous (NH(4))(2)SO(4)-malonic acid particles (with dry organic mole fraction = 0.36), the rates are not as dependent on RH. The homogeneous nucleation rates for aqueous (NH(4))(2)SO(4) particles were parametrized using classical nucleation theory, and from this analysis we determined that the interfacial surface tension between the crystalline ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is between 0.053 and 0.070 J m(-2).

Biomimetic Interfacial Electron-Induced Electrochemiluminesence.

PubMed

Pu, Guiqiang; Zhang, Dongxu; Mao, Xiang; Zhang, Zhen; Wang, Huan; Ning, Xingming; Lu, Xiaoquan

2018-04-17

We provide here, for the first time, a new interfacial electron-induced electrochemiluminescence (IEIECL) system, realizing bionic construction of bioluminescence (BL) by exploiting electrochemiluminescence (ECL) and ITIES (the interface between two immiscible electrolyte solutions). Significantly, the superiority of the IEIECL system is embodied with the solution of the two bottlenecks encountered in the conventional ECL innovation: that are (a) the applications of hydrophobic luminophores in more commonly used aqueous solution are inhibited tremendously due to the poor inherent solubility and the instability of radicals and (b) the analytes, insoluble in water, are hard to be discovered in an aqueous system because of too little content. More productive IEIECL radiation, analogous to BL, originates from the triplet excited state porphyrin in comparison to the homogeneous ECL. The mechanism of IEIECL, as well as the interaction mechanism between IEIECL and charge transfer (comprising electron transfer (ET), ion transfer (IT), and facilitated ion transfer (FIT)) at the ITIES, are explored in detail. Finally, we emphasize the actual application potential of the IEIECL system with the detection of cytochrome c (Cyt c); it is a key biomolecule in the electron transport chain in the process of biological oxidation and is also an intermediate species in apoptosis. Potentially, the IEIECL system permits ones to explore the lifetime and diffusion path of free radicals, as well as imparting a possibility for the construction of a bionic sensor.

Deep eutectic solvent based gas-assisted dispersive liquid-phase microextraction combined with gas chromatography and flame ionization detection for the determination of some pesticide residues in fruit and vegetable samples.

PubMed

Farajzadeh, Mir Ali; Sattari Dabbagh, Masoumeh; Yadeghari, Adeleh

2017-05-01

In this study, a gas-assisted dispersive liquid-phase microextraction method using a deep eutectic solvent as the extraction solvent combined with gas chromatography and flame ionization detection was developed for the extraction and determination of some pesticide residues in vegetable and fruit juice samples. In this method, choline chloride and 4-chlorophenol at a molar ratio of 1:2 were mixed. By heating and vortexing, a clear, water-immiscible, and homogeneous liquid was formed. The obtained deep eutectic solvent was added to an aqueous solution of the analytes in a conical test tube. Air was bubbled into the aqueous solution and a cloudy solution was obtained. During this step, the analytes were extracted into the fine droplets of the extraction solvent. After centrifugation, an aliquot of the settled phase was injected into the separation system. Under the optimum extraction conditions, enrichment factors, and extraction recoveries were obtained in the ranges of 247-355 and 49-71%, respectively. The obtained values for the limits of detection and quantification were in the ranges of 0.24-1.4 and 0.71-4.2 μg/L, respectively. The proposed method is simple, fast, efficient, and inexpensive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ABC Triblock Copolymer Worms: Synthesis, Characterization, and Evaluation as Pickering Emulsifiers for Millimeter-Sized Droplets

PubMed Central

2016-01-01

Polymerization-induced self-assembly (PISA) is used to prepare linear poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate)–poly(benzyl methacrylate) [PGMA–PHPMA–PBzMA] triblock copolymer nano-objects in the form of a concentrated aqueous dispersion via a three-step synthesis based on reversible addition–fragmentation chain transfer (RAFT) polymerization. First, GMA is polymerized via RAFT solution polymerization in ethanol, then HPMA is polymerized via RAFT aqueous solution polymerization, and finally BzMA is polymerized via “seeded” RAFT aqueous emulsion polymerization. For certain block compositions, highly anisotropic worm-like particles are obtained, which are characterized by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The design rules for accessing higher order morphologies (i.e., worms or vesicles) are briefly explored. Surprisingly, vesicular morphologies cannot be accessed by targeting longer PBzMA blocks—instead, only spherical nanoparticles are formed. SAXS is used to rationalize these counterintuitive observations, which are best explained by considering subtle changes in the relative enthalpic incompatibilities between the three blocks during the growth of the PBzMA block. Finally, the PGMA–PHPMA–PBzMA worms are evaluated as Pickering emulsifiers for the stabilization of oil-in-water emulsions. Millimeter-sized oil droplets can be obtained using low-shear homogenization (hand-shaking) in the presence of 20 vol % n-dodecane. In contrast, control experiments performed using PGMA–PHPMA diblock copolymer worms indicate that these more delicate nanostructures do not survive even these mild conditions. PMID:27795581

The use of synthesized aqueous solutions for determining strontium sorption isotherms

USGS Publications Warehouse

Liszewski, M.J.; Bunde, R.L.; Hemming, C.; Rosentreter, J.; Welhan, J.

1998-01-01

The use of synthesized aqueous solutions for determining experimentally derived strontium sorption isotherms of sediment was investigated as part of a study accessing strontium chemical transport properties. Batch experimental techniques were used to determine strontium sorption isotherms using synthesized aqueous solutions designed to chemically represent water from a natural aquifer with respect to major ionic character and pH. A strontium sorption isotherm for a sediment derived using a synthesized aqueous solution was found to be most comparable to an isotherm derived using natural water when the synthesized aqueous solution contained similar concentrations of calcium and magnesium. However, it is difficult to match compositions exactly due to the effects of disequilibrium between the solution and the sediment. Strong linear relations between sorbed strontium and solution concentrations of calcium and magnesium confirm that these cations are important co-constituents in these synthesized aqueous solutions. Conversely, weak linear relations between sorbed strontium and solution concentrations of sodium and potassium indicate that these constituents do not affect sorption of strontium. The addition of silica to the synthesized aqueous solution does not appreciably affect the resulting strontium sorption isotherm.

Activity of water in aqueous systems; a frequently neglected property.

PubMed

Blandamer, Mike J; Engberts, Jan B F N; Gleeson, Peter T; Reis, Joao Carlos R

2005-05-01

In this critical review, the significance of the term 'activity' is examined in the context of the properties of aqueous solutions. The dependence of the activity of water(l) at ambient pressure and 298.15 K on solute molality is examined for aqueous solutions containing neutral solutes, mixtures of neutral solutes and salts. Addition of a solute to water(l) always lowers its thermodynamic activity. For some solutes the stabilisation of water(l) is less than and for others more than in the case where the thermodynamic properties of the aqueous solution are ideal. In one approach this pattern is accounted for in terms of hydrate formation. Alternatively the pattern is analysed in terms of the dependence of practical osmotic coefficients on the composition of the aqueous solution and then in terms of solute-solute interactions. For salt solutions the dependence of the activity of water on salt molalities is compared with that predicted by the Debye-Hückel limiting law. The analysis is extended to consideration of the activities of water in binary aqueous mixtures. The dependence on mole fraction composition of the activity of water in binary aqueous mixtures is examined. Different experimental methods for determining the activity of water in aqueous solutions are critically reviewed. The role of water activity is noted in a biochemical context, with reference to the quality, stability and safety of food and finally with regard to health science.

Fluid inclusions in stony meteorites

NASA Technical Reports Server (NTRS)

Warner, J. L.; Ashwal, L. D.; Bergman, S. C.; Gibson, E. K., Jr.; Henry, D. J.; Lee-Berman, R.; Roedder, E.; Belkin, H. E.

1983-01-01

The fluid inclusions presently described for five stony meteorites brings to seven the number of such meteorites confirmed. Homogenization temperatures are reproducible in each inclusion, and range from 25 C to over 225 C, with some vapor plus liquid inclusions remaining at 225 C, the highest temperature in these microthermometric experiments. Upon cooling, the fluid in some inclusions appears to freeze, as indicated by deformation and immobilization of the vapor bubble at low temperatures. Melting temperatures are by contrast difficult to observe and are not reproducible. Microthermometric data for the fluid in diogenite ALPHA 77256 and inclusions in four chondrites suggest that the fluid is aqueous, with a high solute content.

PROCESS OF COATING METALS WITH BISMUTH OR BISMUTH-BASE ALLOYS

DOEpatents

Beach, J.G.

1958-01-28

A method is described for producing coatings of bismuth or bismuth alloys on a metal base. This is accomplished by electrodepositing the bismuth from an aqueous solution of BiCl/sub 3/, and by making the metal base alternately the cathode and the anode, the cathode periods being twice as long as the anode periods. In one embodiment a nickel coating is first electrodeposited in a known way, and this nickel plated piece is tae base upon which tae bismuth is deposited by the process of this patent. The coated piece is then heat treated to produce a homogeneous Ni--Bi alloy by diffusion.

Method of fabricating nested shells and resulting product

DOEpatents

Henderson, Timothy M.; Kool, Lawrence B.

1982-01-01

A multiple shell structure and a method of manufacturing such structure wherein a hollow glass microsphere is surface treated in an organosilane solution so as to render the shell outer surface hydrophobic. The surface treated glass shell is then suspended in the oil phase of an oil-aqueous phase dispersion. The oil phase includes an organic film-forming monomer, a polymerization initiator and a blowing agent. A polymeric film forms at each phase boundary of the dispersion and is then expanded in a blowing operation so as to form an outer homogeneously integral monocellular substantially spherical thermoplastic shell encapsulating an inner glass shell of lesser diameter.

Highly concentrated phenolic wastewater treatment by heterogeneous and homogeneous photocatalysis: mechanism study by FTIR-ATR.

PubMed

Araña, J; Tello-Rendón, E; Doña-Rodríguez, J M; Campo, C V; Herrera-Melidán, J A; González-Díaz; Pérez-Peña, J

2001-01-01

The degradation of high phenol concentrations (1 g/L) in water solutions by TiO2 photocatalysis and the photo-Fenton reaction has been studied. From the obtained data it may be suggested that degradation of phenol by TiO2-UV takes place onto the catalyst surface by means of peroxo-compounds formation. At low phenol concentrations other mechanism, the insertion of OH. radicals, may be favored. On the other hand, highly concentrated phenol aqueous solutions treatment by the photo-Fenton reaction gives rise to the formation of polyphenolic polymers. These seem to reduce the process rate. Degradation intermediates have been identified by HPLC and FTIR. The FTIR study of the catalyst surface has shown infrared bands attributable to different chemisorbed peroxo-compounds, formates, ortho-formates and carboxylates that can inactivate the catalyst.

Iridium complexes for electrocatalysis

DOEpatents

Sheehan, Stafford Wheeler; Hintermair, Ulrich; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H

2017-10-17

Solution-phase (e.g., homogeneous) or surface-immobilized (e.g., heterogeneous) electrode-driven oxidation catalysts based on iridium coordination compounds which self-assemble upon chemical or electrochemical oxidation of suitable precursors and methods of making and using thereof are. Iridium species such as {[Ir(LX).sub.x(H.sub.2O).sub.y(.mu.-O)].sub.z.sup.m+}.sub.n wherein x, y, m are integers from 0-4, z and n from 1-4 and LX is an oxidation-resistant chelate ligand or ligands, such as such as 2(2-pyridyl)-2-propanolate, form upon oxidation of various molecular iridium complexes, for instance [Cp*Ir(LX)OH] or [(cod)Ir(LX)] (Cp*=pentamethylcyclopentadienyl, cod=cis-cis,1,5-cyclooctadiene) when exposed to oxidative conditions, such as sodium periodate (NaIO.sub.4) in aqueous solution at ambient conditions.

Protein aggregate turbidity: Simulation of turbidity profiles for mixed-aggregation reactions.

PubMed

Hall, Damien; Zhao, Ran; Dehlsen, Ian; Bloomfield, Nathaniel; Williams, Steven R; Arisaka, Fumio; Goto, Yuji; Carver, John A

2016-04-01

Due to their colloidal nature, all protein aggregates scatter light in the visible wavelength region when formed in aqueous solution. This phenomenon makes solution turbidity, a quantity proportional to the relative loss in forward intensity of scattered light, a convenient method for monitoring protein aggregation in biochemical assays. Although turbidity is often taken to be a linear descriptor of the progress of aggregation reactions, this assumption is usually made without performing the necessary checks to provide it with a firm underlying basis. In this article, we outline utilitarian methods for simulating the turbidity generated by homogeneous and mixed-protein aggregation reactions containing fibrous, amorphous, and crystalline structures. The approach is based on a combination of Rayleigh-Gans-Debye theory and approximate forms of the Mie scattering equations. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels

PubMed Central

Zinchenko, Anatoly; Taki, Yosuke; Sergeyev, Vladimir G.; Murata, Shizuaki

2015-01-01

A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed. PMID:28347011

DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels.

PubMed

Zinchenko, Anatoly; Taki, Yosuke; Sergeyev, Vladimir G; Murata, Shizuaki

2015-03-03

A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed.

Laser-induced breakdown spectroscopic detection of trace level heavy metal in solutions on a laser-pretreated metallic target.

PubMed

Niu, Sheng; Zheng, Lijuan; Khan, Abdul Qayyum; Feng, Guang; Zeng, Heping

2018-03-01

A fast and sensitive analysis for trace level heavy metals in aqueous solution was realized by using an improved laser induced breakdown spectroscopy (LIBS) methodology. Solutions containing heavy metal elements, Ni, Cr, and Cd, were concentrated in a laser-pretreated area (25 × 20mm 2 ) of a polished aluminum target surface, wherein pretreated grooves enabled homogeneous distribution of the metallic solutions in the well-defined area, and laser ablation of the aluminum target produced unique plasma excitation of various metallic ions. For 1-mL solutions deposited, we obtained an analytical precision of about 7% relative standard deviation (RSD), and limits of detection (LODs) of 22, 19, and 184μg/L for Ni, Cr, and Cd, respectively. Moreover, the laser-pretreated metallic microstructure allowed more solution deposited with the help of a hot plate, which supported improvement of LODs to sub-μg/L level for Cr and Ni and μg/L level for Cd with about 20-mL solution engaged in the enrichment processes. The applicability of the proposed methodology was validated on certified reference materials and real river water. Copyright © 2017 Elsevier B.V. All rights reserved.

Membrane separation for non-aqueous solution

NASA Astrophysics Data System (ADS)

Widodo, S.; Khoiruddin; Ariono, D.; Subagjo; Wenten, I. G.

2018-01-01

Membrane technology has been widely used in a number of applications competing with conventional technologies in various ways. Despite the enormous applications, they are mainly used for the aqueous system. The use of membrane-based processes in a non-aqueous system is an emerging area. This is because developed membranes are still limited in separations involving aqueous solution which show several drawbacks when implemented in a non-aqueous system. The purpose of this paper is to provide a review of the current application of membrane processes in non-aqueous solutions, such as mineral oil treatment, vegetable oil processing, and organic solvent recovery. Developments of advanced membrane materials for the non-aqueous solutions such as super-hydrophobic and organic solvent resistant membranes are reviewed. In addition, challenges and future outlook of membrane separation for the non-aqueous solution are discussed.

Chemical composition and functional properties of gum exudates from the trunk of the almond tree (Prunus dulcis).

PubMed

Mahfoudhi, N; Chouaibi, M; Donsì, F; Ferrari, G; Hamdi, S

2012-06-01

The physicochemical components and functional properties of the gum exudates from the trunk of the almond tree (Prunus dulcis) have been investigated, along with the emulsification and foaming properties. The gum exudates are composed on dry weight basis by 2.45% of proteins, 0.85% of fats and 92.36% of carbohydrates. The latter consist of arabinose, xylitol, galactose and uronic acid (46.8 : 10.9 : 35.5 : 6.0 mass ratio) with traces of rhamnose, mannose and glucose. Moreover, gum exudates are rich in minerals, such as sodium, potassium, magnesium, calcium and iron. The emulsifying capacity was studied for a 20% w/w olive oil in water emulsion as a function of gum concentration (from 3% to 12% w/w in the aqueous phase) as well as pH levels (from 3.0 to 10.0). The most stable and homogeneous emulsion was prepared with an 8% w/w aqueous almond gum solution at a pH between 5.0 and 8.0. In particular, for the same formulation, the emulsion processed by high pressure homogenization (5 passes at 200 MPa) resulted to be extremely stable under accelerated ageing, exhibiting no significant change in droplet size distribution for 14 days at 55 °C. All the tested systems exhibited an extremely low foaming capacity.

Water-soluble polymers for recovery of metal ions from aqueous streams

DOEpatents

Smith, Barbara F.; Robison, Thomas W.

1998-01-01

A process of selectively separating a target metal contained in an aqueous solution by contacting the aqueous solution containing a target metal with an aqueous solution including a water-soluble polymer capable of binding with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solution is disclosed.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1998-01-01

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

Needle-like Co3O4 anchored on the graphene with enhanced electrochemical performance for aqueous supercapacitors.

PubMed

Guan, Qun; Cheng, Jianli; Wang, Bin; Ni, Wei; Gu, Guifang; Li, Xiaodong; Huang, Ling; Yang, Guangcheng; Nie, Fude

2014-05-28

We synthesized the needle-like cobalt oxide/graphene composites with different mass ratios, which are composed of cobalt oxide (Co3O4 or CoO) needle homogeneously anchored on graphene nanosheets as the template, by a facile hydrothermal method. Without the graphene as the template, the cobalt precursor tends to group into urchin-like spheres formed by many fine needles. When used as electrode materials of aqueous supercapacitor, the composites of the needle-like Co3O4/graphene (the mass ratio of graphene oxide(GO) and Co(NO3)2·6H2O is 1:5) exhibit a high specific capacitance of 157.7 F g(-1) at a current density of 0.1 A g(-1) in 2 mol L(-1) KOH aqueous solution as well as good rate capability. Meanwhile, the capacitance retention keeps about 70% of the initial value after 4000 cycles at a current density of 0.2 A g(-1). The enhancement of excellent electrochemical performances may be attributed to the synergistic effect of graphene and cobalt oxide components in the unique multiscale structure of the composites.

Effects of DA-6034 on aqueous tear fluid secretion and conjunctival goblet cell proliferation.

PubMed

Choi, Seul Min; Lee, Yeong Geon; Seo, Mi Jung; Kang, Kyung Koo; Ahn, Byoung Ok; Yoo, Moohi

2009-06-01

This study was conducted to evaluate the effect of DA-6034, a potent secretagogue, on aqueous tear fluid secretion and its quality in normal rabbit. We also evaluated, in animal models of experimentally induced dry eye disease, its effectiveness over time to stimulate aqueous tear production by ocular ferning test and goblet cell proliferation. Aqueous tear production, total protein levels, and glycoprotein levels in normal rabbits were evaluated after topical application of DA-6034 (0.3, 1, and 3%). Moreover, time course aqueous tear volume measurement and ocular ferning test in tear fluid were performed in dry eyes of rabbits that had been given 1% atropine sulfate, topically. Altogether, tear fluid production and conjunctival goblet cell numbers were measured in dry eyes of mice that had been given topical scopolamine. Topical application of DA-6034 (0.3, 1, and 3%) significantly increased (P < 0.05) aqueous tear production in a concentration-dependent manner in normal rabbits. There was no change in total protein levels while glycoprotein levels were significantly increased (P < 0.05) at 3% DA-6034. The increase in aqueous tear fluid was significant (P < 0.05) and lasted for 2 h post-instillation in dry eyes of rabbits that had been given 1% atropine sulfate; 10-day repeated instillation of the drug in this model resulted in large and homogeneous fern-like tear patterns. In a mouse model, DA-6034 given as a 3% eyedrop solution significantly increased (P < 0.05) tear fluid production and conjunctival goblet cell number. These results suggest that DA-6034 accelerates not only tear secretion but also mucin production and may be a potential therapeutic agent for the treatment of dry eye disease.

Simultaneous Separation of Manganese, Cobalt, and Nickel by the Organic-Aqueous-Aqueous Three-Phase Solvent Extraction

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Uda, Tetsuya

2016-04-01

This research outlines an organic-aqueous-aqueous three-phase solvent extraction method and proposes its use in a new metal separation process for the recycling of manganese (Mn), cobalt (Co), and nickel (Ni) from used lithium ion batteries (LIBs). The three-phase system was formed by mixing xylene organic solution, 50 pct polyethylene glycol (PEG) aqueous solution, and 1 mol L-1 sodium sulfate (Na2SO4) aqueous solution. The xylene organic solution contained 2-ethylhexylphosphonic acid (D2EHPA) as an extractant for Mn ion, and the Na2SO4 aqueous solution contained 1 mol L-1 potassium thiocyanate (KSCN) as an extractant for Co ion. Concentrations of the metal ions were varied by dissolving metal sulfates in the Na2SO4 aqueous solution. As a result of the experiments, Mn, Co, and Ni ions were distributed in the xylene organic phase, PEG-rich aqueous phase, and Na2SO4-rich aqueous phase, respectively. The separation was effective when the pH value was around 4. Numerical simulation was also conducted in order to predict the distribution of metal ions after the multi-stage counter-current extractions.

EMERGING TECHNOLOGY BULLETIN: REMOVAL OF PHENOL FROM AQUEOUS SOLUTIONS USING HIGH ENERGY ELECTRON BEAM IRRADIATION

EPA Science Inventory

Irradiation of aqueous solutions with high-energy electrons results in the formation of the aqueous electron, hydrogen radical, H-, and the hydroxyl radical, OH-. These reactive transient species initiate chemical reactions capable of destroying organic compounds in aqueous solut...

REMOVAL OF CHLORIDE FROM AQUEOUS SOLUTIONS

DOEpatents

Schulz, W.W.

1959-08-01

The removal of chlorides from aqueons solutions is described. The process involves contacting the aqueous chloride containing solution with a benzene solution about 0.005 M in phenyl mercuric acetate whereby the chloride anions are taken up by the organic phase and separating the organic phase from the aqueous solutions.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1998-01-13

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution. 7 figs.

Phase-separable aqueous amide solutions as a thermal history indicator.

PubMed

Kitsunai, Makoto; Miyajima, Kentaro; Mikami, Yuzuru; Kim, Shokaku; Hirasawa, Akira; Chiba, Kazuhiro

2008-12-01

Aqueous solutions of several new amide compounds for use as simple thermal history indicators in the low-temperature transport of food and other products were synthesized. The phase transition temperatures of the aqueous solutions can be freely adjusted by changing the amide-water ratio in solution, the sodium chloride concentration of the water, and the type of amide compound. It is expected that these aqueous solutions can be applied as new thermal history indicators.

Finite-size effects in simulations of electrolyte solutions under periodic boundary conditions

NASA Astrophysics Data System (ADS)

Thompson, Jeffrey; Sanchez, Isaac

The equilibrium properties of charged systems with periodic boundary conditions may exhibit pronounced system-size dependence due to the long range of the Coulomb force. As shown by others, the leading-order finite-size correction to the Coulomb energy of a charged fluid confined to a periodic box of volume V may be derived from sum rules satisfied by the charge-charge correlations in the thermodynamic limit V -> ∞ . In classical systems, the relevant sum rule is the Stillinger-Lovett second-moment (or perfect screening) condition. This constraint implies that for large V, periodicity induces a negative bias of -kB T(2 V) - 1 in the total Coulomb energy density of a homogeneous classical charged fluid of given density and temperature. We present a careful study of the impact of such finite-size effects on the calculation of solute chemical potentials from explicit-solvent molecular simulations of aqueous electrolyte solutions. National Science Foundation Graduate Research Fellowship Program, Grant No. DGE-1610403.

Organelle-mimicking liposome dissociates G-quadruplexes and facilitates transcription

PubMed Central

Pramanik, Smritimoy; Tateishi-Karimata, Hisae; Sugimoto, Naoki

2014-01-01

Important biological reactions involving nucleic acids occur near the surface of membranes such as the nuclear membrane (NM) and rough endoplasmic reticulum (ER); however, the interactions between biomembranes and nucleic acids are poorly understood. We report here that transcription was facilitated in solution with liposomes, which mimic a biomembrane surface, relative to the reaction in a homogeneous aqueous solution when the template was able to form a G-quadruplex. The G-quadruplex is known to be an inhibitor of transcription, but the stability of the G-quadruplex was decreased at the liposome surface because of unfavourable enthalpy. The destabilization of the G-quadruplex was greater at the surface of NM- and ER-mimicking liposomes than at the surfaces of liposomes designed to mimic other organelles. Thermodynamic analyses revealed that the G-rich oligonucleotides adopted an extended structure at the liposome surface, whereas in solution the compact G-quadruplex was formed. Our data suggest that changes in structure and stability of nucleic acids regulate biological reactions at membrane surfaces. PMID:25336617

A liquid-liquid transition in supercooled aqueous solution related to the HDA-LDA transition.

PubMed

Woutersen, Sander; Ensing, Bernd; Hilbers, Michiel; Zhao, Zuofeng; Angell, C Austen

2018-03-09

Simulations and theory suggest that the thermodynamic anomalies of water may be related to a phase transition between two supercooled liquid states, but so far this phase transition has not been observed experimentally because of preemptive ice crystallization. We used calorimetry, infrared spectroscopy, and molecular dynamics simulations to investigate a water-rich hydrazinium trifluoroacetate solution in which the local hydrogen bond structure surrounding a water molecule resembles that in neat water at elevated pressure, but which does not crystallize upon cooling. Instead, this solution underwent a sharp, reversible phase transition between two homogeneous liquid states. The hydrogen-bond structures of these two states are similar to those established for high- and low-density amorphous (HDA and LDA) water. Such structural similarity supports theories that predict a similar sharp transition in pure water under pressure if ice crystallization could be suppressed. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Effect of high pressure homogenization on aqueous phase solvent extraction of lipids from Nannochloris Oculata microalgae

DOE PAGES

Samarasinghe, Nalin; Fernando, Sandun; Faulkner, William B.

2012-12-01

The ability to extract lipids from high-moisture Nannochloris Oculata algal biomass disrupted with high pressure homogenization was investigated. During the first phase, the effect of high pressure homogenization (system pressure and number of passes) on disrupting aqueous algae (of different concentrations and degree of stress) was investigated. Secondly, the effect of degree of cell wall disruption on the amount of lipids extracted with three solvents, namely: hexane, dichloromethane and chloroform, were compared. Studies reveled that high pressure homogenization is effective on cell disruption while the amount of system pressure being the most significant factor affecting the degree of cell breakage.more » Although the number of passes had some impact, the level of disruption seemed to level-off after a certain number of passes. The study revealed that slightly polar solvents (such as chloroform and dichloromethane) performed better in aqueous-phase lipid extractions as compared to hexane. Also, it was revealed that it was not necessary to disrupt the algal cells completely to achieve appreciable levels of lipid yields. In fact, conditions that exerted only 20% of the cells to completely disrupt, allowed sufficient damage to liberate most of the lipids contained in the remainder of the cells.« less

Effect of high pressure homogenization on aqueous phase solvent extraction of lipids from Nannochloris Oculata microalgae

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

Samarasinghe, Nalin; Fernando, Sandun; Faulkner, William B.

The ability to extract lipids from high-moisture Nannochloris Oculata algal biomass disrupted with high pressure homogenization was investigated. During the first phase, the effect of high pressure homogenization (system pressure and number of passes) on disrupting aqueous algae (of different concentrations and degree of stress) was investigated. Secondly, the effect of degree of cell wall disruption on the amount of lipids extracted with three solvents, namely: hexane, dichloromethane and chloroform, were compared. Studies reveled that high pressure homogenization is effective on cell disruption while the amount of system pressure being the most significant factor affecting the degree of cell breakage.more » Although the number of passes had some impact, the level of disruption seemed to level-off after a certain number of passes. The study revealed that slightly polar solvents (such as chloroform and dichloromethane) performed better in aqueous-phase lipid extractions as compared to hexane. Also, it was revealed that it was not necessary to disrupt the algal cells completely to achieve appreciable levels of lipid yields. In fact, conditions that exerted only 20% of the cells to completely disrupt, allowed sufficient damage to liberate most of the lipids contained in the remainder of the cells.« less

LASERS, ACTIVE MEDIA: The aqueous-polyelectrolyte dye solution as an active laser medium

NASA Astrophysics Data System (ADS)

Akimov, A. I.; Saletskii, A. M.

2000-11-01

The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes — polyacrylic and polymethacrylic acids — are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions.

Solution-phase electronegativity scale: insight into the chemical behaviors of metal ions in solution.

PubMed

Li, Keyan; Li, Min; Xue, Dongfeng

2012-04-26

By incorporating the solvent effect into the Born effective radius, we have proposed an electronegativity scale of metal ions in aqueous solution with the most common oxidation states and hydration coordination numbers in terms of the effective ionic electrostatic potential. It is found that the metal ions in aqueous solution are poorer electron acceptors compared to those in the gas phase. This solution-phase electronegativity scale shows its efficiency in predicting some important properties of metal ions in aqueous solution such as the aqueous acidities of the metal ions, the stability constants of metal complexes, and the solubility product constants of the metal hydroxides. We have elaborated that the standard reduction potential and the solution-phase electronegativity are two different quantities for describing the processes of metal ions in aqueous solution to soak up electrons with different final states. This work provides a new insight into the chemical behaviors of the metal ions in aqueous solution, indicating a potential application of this electronegativity scale to the design of solution reactions.

Structurally homogeneous nanosheets from self-assembly of a collagen-mimetic peptide.

PubMed

Jiang, Tao; Xu, Chunfu; Zuo, Xiaobing; Conticello, Vincent P

2014-08-04

A collagen-mimetic peptide, NSIII, has been designed with three sequential blocks having positive, neutral, and negative charges, respectively. The non-canonical imino acid, (2S,4S)-4-aminoproline (amp), was used to specify the positive charges at the Xaa positions of (Xaa-Yaa-Gly) triads in the N-terminal domain of NSIII. Peptide NSIII underwent self-assembly from aqueous solution to form a highly homogeneous population of nanosheets. Two-dimensional crystalline sheets formed in which the length of the peptide defined the height of the sheets. These results contrasted with prior results on a similar multi-domain collagen-mimetic polypeptides in which the sheets had highly polydisperse distribution of sizes in the (x/y)- and (z)-dimensions. The structural differences between the two nanosheet assemblies were interpreted in terms of the relative stereoelectronic effects of the different aminoproline derivatives on the local triple helical conformation of the peptides. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method of precipitating uranium from an aqueous solution and/or sediment

DOEpatents

Tokunaga, Tetsu K; Kim, Yongman; Wan, Jiamin

2013-08-20

A method for precipitating uranium from an aqueous solution and/or sediment comprising uranium and/or vanadium is presented. The method includes precipitating uranium as a uranyl vanadate through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium and a solution comprising a monovalent or divalent cation to form the corresponding cation uranyl vanadate precipitate. The method also provides a pathway for extraction of uranium and vanadium from an aqueous solution and/or sediment.

SEPARATION OF SCANDIUM VALUES FORM IRON VALUES BY SOLVENT EXTRACTION

DOEpatents

Kuhlman, C.W. Jr.; Lang, G.P.

1961-12-19

A process is given for separating scandium from trivalent iron values. In this process, an aqueous nitric acid solution is contacted with a water- immiscible alkyl phosphate solution, the aqueous solution containing the values to be separated, whereby the scandium is taken up by the alkyl phosphate. The aqueous so1ution is preferably saturated with magnesium nitrate to retain the iron in the aqueous solution. (AEC)

Evolution of Spatial pH Distribution in Aqueous Solution induced by Atmospheric Pressure Plasma

NASA Astrophysics Data System (ADS)

Takahashi, Shigenori; Mano, Kakeru; Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu

2016-09-01

Discharge plasma at gas-liquid interface produces some active species, and then they affect chemical reactions in aqueous solution, where pH of aqueous solution is changed due to redox species. The pH change of aqueous solution is an important factor for chemical reactions. However, spatial pH distribution in a reactor during the discharge has not been clarified yet. Thus, this work focused on spatial pH distribution of aqueous solution when pulsed discharge plasma was generated from a copper electrode in gas phase to aqueous solution in a reactor. Experiments were conducted using positive unipolar pulsed power. The unipolar pulsed voltage at +8.0 kV was applied to the copper electrode and the bottom of the reactor was grounded. The size of the reactor was 80 mm wide, 10 mm deep, and 40 mm high. The electrode was set at distance of 2 mm from the solution surface. Anthocyanins were contained in the aqueous solution as a pH indicator. The change pH solution spread horizontally, and low pH region of 10 mm in depth was formed. After discharge for 10 minutes, the low pH region was diffused toward the bottom of the reactor. After discharge for 60 minutes, the pH of the whole solution decreased.

Solvents of pus-medicines with physical-chemical aggressive action

NASA Astrophysics Data System (ADS)

Urakov, A.; Urakova, N.; Reshetnikov, A.; Kopylov, M.; Chernova, L.

2017-01-01

In laboratory and clinical conditions was studied rheology of pus and sulfuric tubes after their interaction with aqueous solutions of drugs from different pharmacological groups. It is shown that solutions of almost all medicines can influence or not influence on their rheology, because local action is determined not by the name, dose or route of administration of medicines. It is established that only physical-chemical properties of fluids and physical-chemical factors of their interaction with dense pus can give them the ability to dissolve or thickening pus. We found that deliberate change physical-chemical properties of medicines solutions from various pharmacological groups, namely, raising the temperature to +42°C, increasing the alkalinity above pH 8.1 and aeration as for example by introducing carbon dioxide under pressure of 0.2 ATM, or by introducing hydrogen peroxide in 0.5 - 3%, turning them into solvents of pus, ear wax and sulfuric tubes. Discovered that solutions of drugs with such physical-chemical activity may turn thick pus and solid sulfur tube in a homogeneous liquid after a few minutes after injecting them into these biological mass.

Hydrogen production by sodium borohydride in NaOH aqueous solution

NASA Astrophysics Data System (ADS)

Wang, Q.; Zhang, L. F.; Zhao, Z. G.

2018-01-01

The kinetics of hydrolysis reaction of NaBH4 in NaOH aqueous solution is studied. The influence of pH of the NaOH aqueous solution on the rate of hydrogen production and the hydrogen production efficiency are studied for the hydrolysis reaction of NaBH4. The results show that the activation energy of hydrolysis reaction of NaBH4 increased with the increase of the initial pH of NaOH aqueous solution.With the increasing of the initial pH of NaOH aqueous solution, the rate of hydrogen production and hydrogen production efficiency of NaBH4 hydrolysis decrease.

Homogenous UV/periodate process in treatment of p-nitrophenol aqueous solutions under mild operating conditions.

PubMed

Saien, Javad; Fallah Vahed Bazkiaei, Marzieh

2018-07-01

Aqueous solutions of p-nitrophenol (PNP) were treated with UV-activated potassium periodate (UV/KPI) in an efficient photo-reactor. Either periodate or UV alone had little effect; however, their combination led to a significant degradation and mineralization. The response surface methodology was employed for design of experiments and optimization. The optimum conditions for treatment of 30 mg/L of the substrate were determined as [KPI] = 386.3 mg/L, pH = 6.2 and T = 34.6°C, under which 79.5% degradation was achieved after 60 min. Use of 25 and 40 kHz ultrasound waves caused the degradation to enhance to 88.3% and 92.3%, respectively. The intermediates were identified by gas chromatography-mass spectroscopy analysis, leading to propose the reaction pathway. The presence of water conventional bicarbonate, chloride, sulfate and nitrate anions caused unfavorable effects in efficiency. Meanwhile, the kinetic study showed that PNP degradation follows a pseudo-first-order reaction and the activation energy was determined. The irradiation energy consumption required for one order of magnitude degradation was estimated as 11.18 kWh/m 3 . Accordingly, comparison with the previously reported processes showed the superiority of PNP treatment with the employed process.

Structure of modified [epsilon]-polylysine micelles and their application in improving cellular antioxidant activity of curcuminoids

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

Yu, Hailong; Li, Ji; Shi, Ke

The micelle structure of octenyl succinic anhydride modified {var_epsilon}-polylysine (M-EPL), an anti-microbial surfactant prepared from natural peptide {var_epsilon}-polylysine in aqueous solution has been studied using synchrotron small-angle X-ray scattering (SAXS). Our results revealed that M-EPLs formed spherical micelles with individual size of 24-26 {angstrom} in aqueous solution which could further aggregate to form a larger dimension with averaged radius of 268-308 {angstrom}. Furthermore, M-EPL micelle was able to encapsulate curcuminoids, a group of poorly-soluble bioactive compounds from turmeric with poor oral bioavailability, and improve their water solubility. Three loading methods, including solvent evaporation, dialysis, and high-speed homogenization were compared. Themore » results indicated that the dialysis method generated the highest loading capacity and curcuminoids water solubility. The micelle encapsulation was confirmed as there were no free curcuminoid crystals detected in the differential scanning calorimetry analysis. It was also demonstrated that M-EPL encapsulation stabilized curcuminoids against hydrolysis at pH 7.4 and the encapsulated curcuminoids showed elevated cellular antioxidant activity compared with free curcuminoids. This work suggested that M-EPL could be used as new biopolymer micelles for delivering poorly soluble drugs/phytochemicals and improving their bioactivities.« less

Assessment of Fenton's reagent and ozonation as pre-treatments for increasing the biodegradability of aqueous diethanolamine solutions from an oil refinery gas sweetening process.

PubMed

Durán-Moreno, A; García-González, S A; Gutiérrez-Lara, M R; Rigas, F; Ramírez-Zamora, R M

2011-02-28

The aim of this work was to evaluate the efficiency of three chemical oxidation processes for increasing the biodegradability of aqueous diethanolamine solutions (aqueous DEA solutions), to be used as pre-treatments before a biological process. The raw aqueous DEA solution, sourced from a sour gas sweetening plant at a Mexican oil refinery, was first characterized by standardized physico-chemical methods. Then experiments were conducted on diluted aqueous DEA solutions to test the effects of Fenton's reagent, ozone and ozone-hydrogen peroxide on the removal of some physicochemical parameters of these solutions. Lastly, biodegradability tests based on Dissolved Organic Carbon Die Away OECD301-A, were carried out on a dilution of the raw aqueous DEA solution and on the treated aqueous DEA solutions, produced by applying the best experimental conditions determined during the aforementioned oxidation tests. Experimental results showed that for aqueous DEA solutions treated with Fenton's reagent, the best degradation rate (70%) was obtained at pH 2.8, with Fe(2+) and H(2)O(2) at doses of 1000 and 10,000 mg/L respectively. In the ozone process, the best degradation (60%) was observed in aqueous DEA solution (100 mg COD/L), using 100 mg O(3)/L at pH 5. In the ozone-hydrogen peroxide process, no COD or DOC removals were observed. The diluted spent diethanolamine solution showed its greatest increase in biodegradability after a reaction period of 28 days when treated with Fenton's reagent, but after only 15 days in the case of ozonation. Copyright © 2011 Elsevier B.V. All rights reserved.

Cryo-irradiation as a terminal method for the sterilization of drug aqueous solutions.

PubMed

Maquille, Aubert; Habib Jiwan, Jean-Louis; Tilquin, Bernard

2008-05-01

The aim of this study is to evaluate the specificities of the irradiation of drugs in frozen aqueous solution. The structures of the degradation products were determined to gain insight into the radiolysis mechanisms occurring in frozen aqueous solutions. Metoclopramide hydrochloride and metoprolol tartrate were chosen as models. The frozen solutions were irradiated at dry ice temperature by high energy electrons at various doses. The drug purity (chemical potency) and the radiolysis products were quantified by HPLC-DAD. Characterization of the degradation products was performed by LC-APCI-MS-MS. The structures of the radiolysis products detected in irradiated frozen aqueous solutions were compared to those detected in solid-state and aqueous solutions (previous studies). For both metoclopramide and metoprolol, solute loss upon irradiation of frozen aqueous solutions was negligible. Five radiolysis products present in traces were identified in irradiated metoclopramide frozen solutions. Three of them were previously identified in solid-state irradiated metoclopramide crystals. The two others were formed following reactions with the hydroxyl radical (indirect effect). Only one fragmentation product was observed in irradiated metoprolol frozen solutions. For both drugs, radiosterilization of frozen solutions, even at high doses (25 kGy), was found to be possible.

Synthesis of monodisperse spherical nanometer ZrO{sub 2} (Y{sub 2}O{sub 3}) powders via the coupling route of w/o emulsion with urea homogenous precipitation

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

Chang, Ying; Dong, Shijie, E-mail: dongsjsj@163.com; Wang, Huihu

2012-03-15

Graphical abstract: In this paper, the weight loss and reaction evolution of ZrO{sub 2} precursor powders are determined by TG-DTA, and 600 Degree-Sign C is the most reasonable calcination temperature of precursor according to the TG-DTA. At the same time, we study the effect of reaction conditions upon the particle sizes, such as concentration of zirconium nitrate solution, reaction temperature and urea content. TEM micrographs of zirconia powders indicated that ZrO{sub 2} nano-powders prepared via the coupling route of w/o emulsion with homogenous precipitation possess spherical shape and excellent dispersing. Highlights: Black-Right-Pointing-Pointer The monodisperse spherical nanometer ZrO{sub 2} (Y{sub 2}O{submore » 3}) powders have been prepared via the coupling route of w/o emulsion with urea homogenous precipitation. Black-Right-Pointing-Pointer The principle of the coupling route of emulsion with homogenous precipitation has been studied. Black-Right-Pointing-Pointer The concentration of zirconium nitrate, reaction temperature of water bath and the quantity of urea effect regularly on the average particle size of products. -- Abstract: Using xylol as the oil phase, span-80 as the surfactant, and an aqueous solution containing zirconium (3 mol% Y{sub 2}O{sub 3}) and urea as the water phase, tetragonal phase ZrO{sub 2} nano-powders have been prepared via the coupling route of w/o emulsion with urea homogenous precipitation. The effects of the zirconium concentration, the reaction temperature and the urea content on the average size of the products have been examined. The as-prepared ZrO{sub 2} powders and the precursor powders were characterized by TGA-DTA, XRD, TEM and BET. Experimental results indicate that ZrO{sub 2} powders prepared via the coupling route of w/o emulsion with urea homogenous precipitation possess some excellent characteristics, such as well-rounded spherical shape and excellent dispersing.« less

Noble metal superparticles and methods of preparation thereof

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

Sun, Yugang; Hu, Yongxing

A method comprises heating an aqueous solution of colloidal silver particles. A soluble noble metal halide salt is added to the aqueous solution which undergoes a redox reaction on a surface of the silver particles to form noble metal/silver halide SPs, noble metal halide/silver halide SPs or noble metal oxide/silver halide SPs on the surface of the silver particles. The heat is maintained for a predetermined time to consume the silver particles and release the noble metal/silver halide SPs, the noble metal halide/silver halide SPs or the noble metal oxide/silver halide SPs into the aqueous solution. The aqueous solution ismore » cooled. The noble metal/silver halide SPs, the noble metal halide/silver halide SPs or noble metal oxide/silver halide SPs are separated from the aqueous solution. The method optionally includes adding a soluble halide salt to the aqueous solution.« less

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

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

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One systemmore » operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.« less

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-07-14

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

Method of determining glass durability

DOEpatents

Jantzen, C.M.; Pickett, J.B.; Brown, K.G.; Edwards, T.B.

1998-12-08

A process is described for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, {Delta}G{sub p}, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, {Delta}G{sub a}, based upon the free energy associated with weak acid dissociation, {Delta}G{sub a}{sup WA}, and accelerated matrix dissolution at high pH, {Delta}G{sub a}{sup SB} associated with solution strong base formation, and determining a final hydration free energy, {Delta}G{sub f}. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log{sub 10}(N C{sub i}(g/L))=a{sub i} + b{sub i}{Delta}G{sub f}. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained. 4 figs.

Method of determining glass durability

DOEpatents

Jantzen, Carol Maryanne; Pickett, John Butler; Brown, Kevin George; Edwards, Thomas Barry

1998-01-01

A process for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, .DELTA.G.sub.p, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, .DELTA.G.sub.a, based upon the free energy associated with weak acid dissociation, .DELTA.G.sub.a.sup.WA, and accelerated matrix dissolution at high pH, .DELTA.G.sub.a.sup.SB associated with solution strong base formation, and determining a final hydration free energy, .DELTA.G.sub.f. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log.sub.10 (N C.sub.i (g/L))=a.sub.i +b.sub.i .DELTA.G.sub.f. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained.

Multi-Scale Modeling of the Gamma Radiolysis of Nitrate Solutions.

PubMed

Horne, Gregory P; Donoclift, Thomas A; Sims, Howard E; Orr, Robin M; Pimblott, Simon M

2016-11-17

A multiscale modeling approach has been developed for the extended time scale long-term radiolysis of aqueous systems. The approach uses a combination of stochastic track structure and track chemistry as well as deterministic homogeneous chemistry techniques and involves four key stages: radiation track structure simulation, the subsequent physicochemical processes, nonhomogeneous diffusion-reaction kinetic evolution, and homogeneous bulk chemistry modeling. The first three components model the physical and chemical evolution of an isolated radiation chemical track and provide radiolysis yields, within the extremely low dose isolated track paradigm, as the input parameters for a bulk deterministic chemistry model. This approach to radiation chemical modeling has been tested by comparison with the experimentally observed yield of nitrite from the gamma radiolysis of sodium nitrate solutions. This is a complex radiation chemical system which is strongly dependent on secondary reaction processes. The concentration of nitrite is not just dependent upon the evolution of radiation track chemistry and the scavenging of the hydrated electron and its precursors but also on the subsequent reactions of the products of these scavenging reactions with other water radiolysis products. Without the inclusion of intratrack chemistry, the deterministic component of the multiscale model is unable to correctly predict experimental data, highlighting the importance of intratrack radiation chemistry in the chemical evolution of the irradiated system.

Determination of volatile bases in seafood using the ammonia ion selective electrode: collaborative study.

PubMed

Ellis, P C; Pivarnik, L F; Thiam, M; Ellis, P C; Pivarnik, L F; Thiam, M

2000-01-01

Nine collaborating laboratories tested a combination of 23 seafood samples for volatile bases using an ammonia ion selective electrode. Results were reported as mg NH3/100 g fish, but the method reflected levels of both ammonia and trimethylamine, which permeated the ammonia membrane. The 23 samples were broken down into 8 blind duplicate pairs, 2 Youden matched pairs, and 3 single samples covering fresh to spoiled product ranging from 8 to 82 mg NH3/100 g. Seven species were evaluated: Atlantic cod, squid, Atlantic halibut, gray sole, monkfish, dogfish, and Atlantic mackerel. The ammonia electrode assay was performed on an aqueous homogenate consisting of 95 mL distilled water and 5.0 g sample tissue. Alkaline ion strength adjusting solution (2 mL) was added to the homogenate to liberate ammonia that was sensed by the ion specific electrode and measured on a precalibrated portable meter. Repeatability standard deviations (RSDr) ranged from 4.2 to 17%; reproducibility standard deviations (RSDR) ranged from 8.8 to 21%. A standard ammonium chloride solution was provided to all laboratories to spike 3 different samples at 10 mg NH3/100 g. Recoveries of added ammonia as ammonium chloride for fresh, borderline, and spoiled samples were 88.6, 107, and 128%, respectively.

Isothermal dehydration of thin films of water and sugar solutions

NASA Astrophysics Data System (ADS)

Heyd, R.; Rampino, A.; Bellich, B.; Elisei, E.; Cesàro, A.; Saboungi, M.-L.

2014-03-01

The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar solutions is investigated with a dual experimental and theoretical approach. A nanoporous paper disk with a homogeneous internal structure was used as a substrate. This experimental set-up makes it possible to gather thermodynamic data under well-defined conditions, develop a numerical model, and extract needed information about the dehydration process, in particular the water activity. It is found that the temperature evolution of the pure water film is not strictly isothermal during the drying process, possibly due to the influence of water diffusion through the cellulose web of the substrate. The role of sugar is clearly detectable and its influence on the dehydration process can be identified. At the end of the drying process, trehalose molecules slow down the diffusion of water molecules through the substrate in a more pronounced way than do the glucose molecules.

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

Isothermal dehydration of thin films of water and sugar solutions

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

Heyd, R.; Rampino, A.; Laboratory of Physical and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste

The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar solutions is investigated with a dual experimental and theoretical approach. A nanoporous paper disk with a homogeneous internal structure was used as a substrate. This experimental set-up makes it possible to gather thermodynamic data under well-defined conditions, develop a numerical model, and extract needed information about the dehydration process, in particular the water activity. It is found that the temperature evolution of the pure water film is not strictly isothermal during the drying process, possibly due to the influence of water diffusion through the cellulose webmore » of the substrate. The role of sugar is clearly detectable and its influence on the dehydration process can be identified. At the end of the drying process, trehalose molecules slow down the diffusion of water molecules through the substrate in a more pronounced way than do the glucose molecules.« less

Conversion of depleted uranium hexafluoride to a solid uranium compound

DOEpatents

Rothman, Alan B.; Graczyk, Donald G.; Essling, Alice M.; Horwitz, E. Philip

2001-01-01

A process for converting UF.sub.6 to a solid uranium compound such as UO.sub.2 and CaF. The UF.sub.6 vapor form is contacted with an aqueous solution of NH.sub.4 OH at a pH greater than 7 to precipitate at least some solid uranium values as a solid leaving an aqueous solution containing NH.sub.4 OH and NH.sub.4 F and remaining uranium values. The solid uranium values are separated from the aqueous solution of NH.sub.4 OH and NH.sub.4 F and remaining uranium values which is then diluted with additional water precipitating more uranium values as a solid leaving trace quantities of uranium in a dilute aqueous solution. The dilute aqueous solution is contacted with an ion-exchange resin to remove substantially all the uranium values from the dilute aqueous solution. The dilute solution being contacted with Ca(OH).sub.2 to precipitate CaF.sub.2 leaving dilute NH.sub.4 OH.

Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions.

PubMed

Walker, Rachel L; Searles, Keith; Willard, Jesse A; Michelsen, Rebecca R H

2013-12-28

Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphology allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.

Influence of the aqueous film coating process on the properties and stability of tablets containing a moisture-labile drug.

PubMed

Ruotsalainen, Mirja; Heinämäki, Jyrki; Taipale, Krista; Yliruusi, Jouko

2003-01-01

The effects of an aqueous film coating process on the morphology and storage stability of hydroxypropyl methylcellulose-coated tablets containing a moisture-labile model drug (acetylsalicylic acid, ASA) were evaluated using an instrumented side-vented tablet pan coater. Coating parameters studied were inlet air absolute humidity 5 g/m3 and 12 g/m3, spraying air pressure 100 kPa and 500 kPa, pan air temperature 35 degrees C and 55 degrees C, and coating solution flow rate 2.2 g/min and 7.8 g/min. The surface roughness of the coatings was measured with a laser profilometer and the chemical hydrolysis of the model drug ASA with an UV-spectrophotometer. The film-coated tablets were stored at 25 degrees C/60% RH and 40 degrees C/75% RH for three months. The high absolute humidity of the inlet air increased the residual water content and surface roughness of the coated tablets. Using a lower coating solution flow rate, higher spraying air pressure and pan temperature the coatings were smooth and homogeneous. In both ambient and accelerated storage conditions, the roughness of the coatings and the hydrolysis of ASA increased, but this was independent of the film coating process. Uniform and smooth hydroxypropyl methylcellulose coatings can be achieved by improved control of process parameters related to the application of the coating solution and water evaporation of the tablet surface.

SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

DOEpatents

Beederman, M.; Vogler, S.; Hyman, H.H.

1959-07-14

The separation of rathenium from a rathenium containing aqueous solution is described. The separation is accomplished by adding sodium nitrite, silver nitrate and ozone to the ruthenium containing aqueous solution to form ruthenium tetroxide and ihen volatilizing off the ruthenium tetroxide.

SEPARATION OF POLONIUM, PROTACTINIUM OR MIXTURES THEREOF IN AQUEOUS SOLUTION FROM BISMUTH, LEAD, ZIRCONIUM AND/OR COLUMBIUM VALUES

DOEpatents

Van Winkle, Q.; Kraus, K.A.

1959-10-27

A process is presented for separating polonium, protactinium, or mixtures thereof in aqueous solution from bismuth, zirconium, lead, and niobium values contained in the solution. The method comprises providing hydrochloric acid in the solution in a concentration of at least 5N. contacting the aqueous solution with a substantially waterimmiscible organic solvent such as diisopropyl ketone, and separating the aqueous phase containing the bismuth, zirconium, lead, and niobium from the organic extract phase containing the polonium, protactinium, or mixture thereof.

Method for hot pressing beryllium oxide articles

DOEpatents

Ballard, Ambrose H.; Godfrey, Jr., Thomas G.; Mowery, Erb H.

1988-01-01

The hot pressing of beryllium oxide powder into high density compacts with little or no density gradients is achieved by employing a homogeneous blend of beryllium oxide powder with a lithium oxide sintering agent. The lithium oxide sintering agent is uniformly dispersed throughout the beryllium oxide powder by mixing lithium hydroxide in an aqueous solution with beryllium oxide powder. The lithium hydroxide is converted in situ to lithium carbonate by contacting or flooding the beryllium oxide-lithium hydroxide blend with a stream of carbon dioxide. The lithium carbonate is converted to lithium oxide while remaining fixed to the beryllium oxide particles during the hot pressing step to assure uniform density throughout the compact.

RECOVERY OF ACTINIDES FROM AQUEOUS NITRIC ACID SOLUTIONS

DOEpatents

Ader, M.

1963-11-19

A process of recovering actinides is presented. Tetravalent actinides are extracted from rare earths in an aqueous nitric acid solution with a ketone and back-extracted from the ketone into an aqueous medium. The aqueous actinide solution thus obtained, prior to concentration by boiling, is sparged with steam to reduce its ketone to a maximum content of 3 grams per liter. (AEC)

Solution spinning of a high-? oxide superconductor: the effect of poly(vinyl alcohol) spinning medium on the critical current density of melt-processed ? superconducting filaments

NASA Astrophysics Data System (ADS)

Tomita, Hisayo; Sunohara, Makoto; Goto, Tomoko; Takahashi, Kiyohisa

1996-12-01

The precursor 0953-2048/9/12/014/img9 filament was prepared by solution spinning through a homogeneous aqueous poly(vinyl alcohol) (PVA) solution of Y, Ba and Cu acetates. The solution spinning was successfully performed using PVA with degrees of polymerization (DP) of 1700 and 2450 and a degree of saponification of 85 mol%. The as-drawn filament was heated to remove volatile components and partially melted to generate a superconducting phase. The effects of the DP of PVA and a content of mixed acetates in the precursor filament on the critical current density 0953-2048/9/12/014/img10 of the melt-processed filament were examined. The higher 0953-2048/9/12/014/img11 was obtained for the filament spun from PVA solution of higher DP and lower acetate content. The highest 0953-2048/9/12/014/img11 value of 0953-2048/9/12/014/img13 at 77 K and 0 T was achieved for the filament spun from the DP 2450 PVA with an acetate to PVA ratio of two.

Preparation and Characterization of Cellulose Gels from Corn Cobs

USDA-ARS?s Scientific Manuscript database

Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hydroxide/sodium hypochlorite and shearing. Initial shearing in a blender broke up cob tissue structure into individual cells and resulted in a gel. Subsequent shearing in a high pressure homogenizer incre...

Preparation and characterization of cellulose gels from corn cobs

USDA-ARS?s Scientific Manuscript database

Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hydroxide/sodium hypochlorite and shearing. Initial shearing in a blender broke up cob tissue structure into individual cells and resulted in a gel. Subsequent shearing in a high pressure homogenizer incre...

ENGINEERING BULLETIN: AIR STRIPPING OF AQUEOUS SOLUTIONS

EPA Science Inventory

Air striding is a means to transfer contaminants from aqueous solutions to air. ontaminants are not destroyed by air stripping but are physically separated from the aqueous solutions. ontaminant vapors are transferred into the air stream and, if necessary, can be treated by incin...

Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

PubMed

Hudait, Arpa; Molinero, Valeria

2014-06-04

Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by solution. We predict that micrometer-sized particles and nanoparticles have the same equilibrium internal structure. The variation of liquid-vapor surface tension with solute concentration is a key factor in determining whether a solution-embedded ice core or vapor-exposed ice cap is the equilibrium structure of the aerosols. In agreement with experiments, we predict that the structure of mixed-phase HNO3-water particles, representative of polar stratospheric clouds, consists of an ice core surrounded by freeze-concentrated solution. The results of this work are important to determine the phase state and internal structure of sea spray ultrafine aerosols and other mixed-phase particles under atmospherically relevant conditions.

Metal separations using aqueous biphasic partitioning systems

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

Chaiko, D.J.; Zaslavsky, B.; Rollins, A.N.

1996-05-01

Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they reviewmore » the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation.« less

Raman spectroscopic study of the conformation of dicarboxylic acid salts in aqueous solutions

NASA Astrophysics Data System (ADS)

Fukushima, Kunio; Watanabe, Toshiaki; Umemura, Matome

1986-08-01

It is already known that the molecules of long chain monocarboxylic acid salts have a tendency to form micelles in aqueous solutions, the molecular chain taking the all- trans zigzag structure. However it is considered difficult for dicarboxylic acid salts to adopt the same structure as the monocarboxylic acid salts as they have two carboxyl groups, one on each end of the molecular chain. Therefore, a special structure is expected to exist for dicarboxylic acid salts in aqueous solution. In order to examine this, Raman spectra of suberic acid salt and azelaic acid salt in aqueous solution were measured and the normal vibrational calculation carried out, showing that dicarboxylic acid salts have a helical structure in aqueous solution.

SOLVENT EXTRACTION PROCESS FOR SEPARATING ACTINIDE AND LANTHANIDE METAL VALUES

DOEpatents

Hildebrandt, R.A.; Hyman, H.H.; Vogler, S.

1962-08-14

A process of countercurrently extracting an aqueous mineral acid feed solution for the separation of actinides from lanthanides dissolved therern is described. The feed solution is made acid-defrcient with alkali metal hydroxide prior to.contact with acid extractant; during extraction, however, acid is transferred from organic to aqueous solution and the aqueous solution gradually becomes acid. The acid-deficient phase ' of the process promotes the extraction of the actinides, while the latter acid phase'' of the process improves retention of the lanthanides in the aqueous solution. This provides for an improved separation. (AEC)

Aqueous Plasma Pharmacy: Preparation Methods, Chemistry, and Therapeutic Applications

PubMed Central

Joslin, Jessica M.; McCall, James R.; Bzdek, Justin P.; Johnson, Derek C.; Hybertson, Brooks M.

2017-01-01

Plasma pharmacy is a subset of the broader field of plasma medicine. Although not strictly defined, the term aqueous plasma pharmacy (APP) is used to refer to the generation and distribution of reactive plasma-generated species in an aqueous solution followed by subsequent administration for therapeutic benefits. APP attempts to harness the therapeutic effects of plasma-generated oxidant species within aqueous solution in various applications, such as disinfectant solutions, cell proliferation related to wound healing, and cancer treatment. The subsequent use of plasma-generated solutions in the APP approach facilitates the delivery of reactive plasma species to internal locations within the body. Although significant efforts in the field of plasma medicine have concentrated on employing direct plasma plume exposure to cells or tissues, here we focus specifically on plasma discharge in aqueous solution to render the solution biologically active for subsequent application. Methods of plasma discharge in solution are reviewed, along with aqueous plasma chemistry and the applications for APP. The future of the field also is discussed regarding necessary research efforts that will enable commercialization for clinical deployment. PMID:28428835

Chemical reactions at aqueous interfaces

NASA Astrophysics Data System (ADS)

Vecitis, Chad David

2009-12-01

Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively `extreme' conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1) Adsorption of dilute PFOS(aq) and PFOA(aq) to acoustically cavitating bubble interfaces was greater than equilibrium expectations due to high-velocity bubble radial oscillations; 2) Relative ozone oxidation kinetics of aqueous iodide, sulfite, and thiosulfate were at variance with previously reported bulk aqueous kinetics; 3) Organics that directly chelated with the anode surface were oxidized by direct electron transfer, resulting in immediate carbon dioxide production but slower overall oxidation kinetics. Chemical reactions at aqueous interfaces can be the rate-limiting step of a reaction network and often display novel mechanisms and kinetics as compared to homogeneous chemistry.

Photoproduction of hydroxyl radicals in aqueous solution with algae under high-pressure mercury lamp.

PubMed

Liu, Xianli; Wu, Feng; Deng, Nansheng

2004-01-01

Photoproduction of hydroxyl radicals (*OH) could be induced in aqueous solution with algae (Nitzschia hantzschiana, etc.) and (or not) Fe3+ under high-pressure mercury lamp with an exposure time of 4 h. *OH was determined by HPLC using benzene as a probe. The photoproduction of *OH increased with increasing algae concentration. Fe3+ could enhance the photoproduction of *OH in aqueous solution with algae. The results showed that the photoproduction of *OH in algal solution with Fe3+ was greater than that in algal solution without Fe3+. The light intensity and pH affected the photoproduction of *OH in aqueous solution with algae with/without Fe3+. The photoproduction of *OH in aqueous solution with algae and Fe3+ under 250 W was greater than that under 125 W HPML. The photoproduction of *OH in algal solution (pH ranged from 4.0 to 7.0) with (or not) Fe3+ at pH 4 was the greatest.

Germanium films by polymer-assisted deposition

DOEpatents

Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

2013-01-15

Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

DYNAMIC AND STATIC PARAMETERS OF THE AQUEOUS HOMOGENEOUS ARMOUR RESEARCH REACTOR

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

Terrell, C.W.; McElroy, W.N.

1959-06-01

A brief description of the aqueous homogeneous Armour Research Reactor is given. The negative reactivity coefficient resulting from a temperature increase was determined over a fuel temperature range of 37 to 150 deg F. Possession of an accurately calibrated rod and temperature coefficient permitted a direct measurement of the void coefficient. The reactor was taken to different power levels, and from the calibrated rod the total reduction in excess reactivity was obtained. During the power increase program additional U/sup 235/ and water were added to the core to determine the worth of U/sup 235/ and water. (W.D.M.)

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.

Tested Demonstrations. Color, Solubility, and Complex Ion Equilibria of Nickel (II) Species in Aqueous Solution.

ERIC Educational Resources Information Center

Gilbert, George L., Ed.; And Others

1980-01-01

Presents three different procedures in which reagents are added in a specified order to a large beaker containing an aqueous solution of nickel sulfate. Complex ions of nickel (II) are prepared by using aqueous solutions of ammonia, ethylenediamine, dimethylglyoxime, and cyanide ion. (CS)

Process for recovering chaotropic anions from an aqueous solution also containing other ions

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1999-01-01

A solid/liquid process for the separation and recovery of chaotropic anions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the chaotropic anions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotrope). A solid/liquid phase admixture of separation particles containing bound chaotropic anions in such an aqueous solution is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture.

Process for recovering chaotropic anions from an aqueous solution also containing other ions

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1999-03-30

A solid/liquid process for the separation and recovery of chaotropic anions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the chaotropic anions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotrope). A solid/liquid phase admixture of separation particles containing bound chaotropic anions in such an aqueous solution is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture. 19 figs.

Steady-state voltammetry of hydroxide ion oxidation in aqueous solutions containing ammonia.

PubMed

Daniele, Salvatore; Baldo, M Antonietta; Bragato, Carlo; Abdelsalam, Mamdouh Elsayed; Denuault, Guy

2002-07-15

An oxidation process observed in dilute aqueous solutions of ammonia was investigated under steady-state conditions with gold microelectrodes with radii in the range 2.5-30 microm. Over the ammonia concentration range 0.1-10 mM, a well-defined voltammetric wave was observed at approximately 1.4 V versus Ag/AgCl. It was attributed to the oxidation of hydroxide ions that arise from the dissociation of the weak base. The steady-state limiting current was found to depend on the concentration of supporting electrolyte, and in solution with low electrolyte, it was enhanced by migration contribution, as expected for a negatively charged species that oxidizes on a positively charged electrode. In addition, the steady-state limiting current was proportional to both the ammonia concentration and the electrode radius. The overall electrode process was analyzed in terms of a CE mechanism (homogeneous chemical reaction preceding the heterogeneous electron transfer) with a fast chemical reaction when measurements were carried out in solutions containing NH3 at < or = 5 mM and with electrodes having a radius of > or = 5 microm. This was ascertained by comparing experimental and theoretical data obtained by simulation. The formation of the soluble complex species Au(NH3)2+ was also considered as a possible alternative to explain the presence of the oxidation wave. This process however was ruled out, as the experimental data did not fit theoretical predictions in any of the conditions employed in the investigation. Instead, the direct oxidation of NH3, probably to N2O, was invoked to explain the anomalous currents found when the CE process was strongly kinetically hindered. Throughout this study, a parallel was made between the CE mechanism investigated here and that known to occur during the hydrogen evolution reaction from weak acids.

Multi-level Quantum Mechanics and Molecular Mechanics Study of Ring Opening Process of Guanine Damage by Hydroxyl Radical in Aqueous Solution.

PubMed

Liu, Peng; Wang, Qiong; Niu, Meixing; Wang, Dunyou

2017-08-10

Combining multi-level quantum mechanics theories and molecular mechanics with an explicit water model, we investigated the ring opening process of guanine damage by hydroxyl radical in aqueous solution. The detailed, atomic-level ring-opening mechanism along the reaction pathway was revealed in aqueous solution at the CCSD(T)/MM levels of theory. The potentials of mean force in aqueous solution were calculated at both the DFT/MM and CCSD(T)/MM levels of the theory. Our study found that the aqueous solution has a significant effect on this reaction in solution. In particular, by comparing the geometries of the stationary points between in gas phase and in aqueous solution, we found that the aqueous solution has a tremendous impact on the torsion angles much more than on the bond lengths and bending angles. Our calculated free-energy barrier height 31.6 kcal/mol at the CCSD(T)/MM level of theory agrees well with the one obtained based on gas-phase reaction profile and free energies of solvation. In addition, the reaction path in gas phase was also mapped using multi-level quantum mechanics theories, which shows a reaction barrier at 19.2 kcal/mol at the CCSD(T) level of theory, agreeing very well with a recent ab initio calculation result at 20.8 kcal/mol.

Method for Non-Invasive Determination of Chemical Properties of Aqueous Solutions

NASA Technical Reports Server (NTRS)

Jones, Alan (Inventor); Thomas, Nathan A. (Inventor); Todd, Paul W. (Inventor)

2016-01-01

A method for non-invasively determining a chemical property of an aqueous solution is provided. The method provides the steps of providing a colored solute having a light absorbance spectrum and transmitting light through the colored solute at two different wavelengths. The method further provides the steps of measuring light absorbance of the colored solute at the two different transmitted light wavelengths, and comparing the light absorbance of the colored solute at the two different wavelengths to determine a chemical property of an aqueous solution.

Stability of the anti-oxidative enzymes in aqueous and detergent solution.

PubMed

Mailer, K; Del Maestro, R F

1991-09-18

Activities of the anti-oxidative enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase were studied in rat tissues to determine the ability of detergents both to solubilize the enzymes and also to stabilize enzyme activity. Rat brain, heart and liver were homogenized in 0.1M KCl, 0.1% sodium dodecyl sulfate, 0.1% lubrol, or 0.1% cetyl-trimethylammonium bromide. In general lubrol was more effective than the other solutions in solubilizing GPx and catalase. Lubrol and 0.1M KCl were equally effective in solubilizing SOD. The highest enzyme activities were (1) SOD: 2484 ng/mg (brain), 2501 ng/mg (heart), and 5586 ng/mg (liver); (2) GPx: 224 mU/mg (brain), 1870 mU/mg (heart), and 7332 mU/mg (liver); (3) catalase: 2.8 mU/mg (brain), 10.6 mU/mg (heart), and 309 mU/mg (liver). While cetyl trimethylammonium bromide is marginally better than sodium dodecyl sulfate in solubilizing active enzyme, neither ionic detergent has any advantage over lubrol or 0.1M KCl. For catalase and GPx, enzyme activity loss with time is biphasic. After initial, rapid activity loss (1-5 days for GPx and 7-10 days for catalase) the differences noted among the homogenizing solutions disappear and very little if any activity loss is noted over the next 2-3 weeks. For catalase and GPx, only baseline enzyme activity from t = 0-3 weeks is found in the most chaotropic solution, 0.1% sodium dodecyl sulfate while biphasic activity loss is most pronounced in 0.1% lubrol. These results may indicate active GPx and catalase species stabilized by a lipid-like environment. Correlating in vitro catalase or GPx measurements with in vivo anti-oxidative protection may underestimate tissue defences.

Amorphous Mixed-Metal Oxide Thin Films from Aqueous Solution Precursors with Near-Atomic Smoothness.

PubMed

Kast, Matthew G; Cochran, Elizabeth A; Enman, Lisa J; Mitchson, Gavin; Ditto, Jeffrey; Siefe, Chris; Plassmeyer, Paul N; Greenaway, Ann L; Johnson, David C; Page, Catherine J; Boettcher, Shannon W

2016-12-28

Thin films with tunable and homogeneous composition are required for many applications. We report the synthesis and characterization of a new class of compositionally homogeneous thin films that are amorphous solid solutions of Al 2 O 3 and transition metal oxides (TMO x ) including VO x , CrO x , MnO x , Fe 2 O 3 , CoO x , NiO, CuO x , and ZnO. The synthesis is enabled by the rapid decomposition of molecular transition-metal nitrates TM(NO 3 ) x at low temperature along with precondensed oligomeric Al(OH) x (NO 3 ) 3-x cluster species, both of which can be processed from aq solution. The films are dense, ultrasmooth (R rms < 1 nm, near 0.1 nm in many cases), and atomically mixed amorphous metal-oxide alloys over a large composition range. We assess the chemical principles that favor the formation of amorphous homogeneous films over rougher phase-segregated nanocrystalline films. The synthesis is easily extended to other compositions of transition and main-group metal oxides. To demonstrate versatility, we synthesized amorphous V 0.1 Cr 0.1 Mn 0.1 Fe 0.1 Zn 0.1 Al 0.5 O x and V 0.2 Cr 0.2 Fe 0.2 Al 0.4 O x with R rms ≈ 0.1 nm and uniform composition. The combination of ideal physical properties (dense, smooth, uniform) and broad composition tunability provides a platform for film synthesis that can be used to study fundamental phenomena when the effects of transition metal cation identity, solid-state concentration of d-electrons or d-states, and/or crystallinity need to be controlled. The new platform has broad potential use in controlling interfacial phenomena such as electron transfer in solar-cell contacts or surface reactivity in heterogeneous catalysis.

Experimental consideration of capillary chromatography based on tube radial distribution of ternary mixture carrier solvents under laminar flow conditions.

PubMed

Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2011-01-01

A capillary chromatography system has been developed based on the tube radial distribution of the carrier solvents using an open capillary tube and a water-acetonitrile-ethyl acetate mixture carrier solution. This tube radial distribution chromatography (TRDC) system works under laminar flow conditions. In this study, a phase diagram for the ternary mixture carrier solvents of water, acetonitrile, and ethyl acetate was constructed. The phase diagram that included a boundary curve between homogeneous and heterogeneous solutions was considered together with the component ratios of the solvents in the homogeneous carrier solutions required for the TRDC system. It was found that the TRDC system performed well with homogeneous solutions having component ratios of the solvents that were positioned near the homogeneous-heterogeneous solution boundary of the phase diagram. For preparing the carrier solutions of water-hydrophilic/hydrophobic organic solvents for the TRDC system, we used for the first time methanol, ethanol, 1,4-dioxane, and 1-propanol, instead of acetonitrile (hydrophilic organic solvent), as well as chloroform and 1-butanol, instead of ethyl acetate (hydrophobic organic solvent). The homogeneous ternary mixture carrier solutions were prepared near the homogeneous-heterogeneous solution boundary. Analyte mixtures of 2,6-naphthalenedisulfonic acid and 1-naphthol were separated with the TRDC system using these homogeneous ternary mixture carrier solutions. The pressure change in the capillary tube under laminar flow conditions might alter the carrier solution from homogeneous in the batch vessel to heterogeneous, thus affecting the tube radial distribution of the solvents in the capillary tube.

Characteristics of regenerated nanocellulosic fibers from cellulose dissolution in aqueous solutions for wood fiber/polypropylene composites

Treesearch

Sangyeob Lee; Hui Pan; Chung Y. Hse; Alfred R. Gunasekaran; Todd F. Shupe

2014-01-01

The effects of aqueous solutions were evaluated on the properties of regenerated cellulosic nanofibers prepared from pure cellulose fibers in various formulations of aqueous solutions. Thermoplastic composites were prepared with reinforcement of the regenerated cellulosic nanofibers. The regenerated cellulosic fibers from cellulosic woody biomass were obtained from...

URANIUM SEPARATION PROCESS

DOEpatents

McVey, W.H.; Reas, W.H.

1959-03-10

The separation of uranium from an aqueous solution containing a water soluble uranyl salt is described. The process involves adding an alkali thiocyanate to the aqueous solution, contacting the resulting solution with methyl isobutyl ketons and separating the resulting aqueous and organic phase. The uranium is extracted in the organic phase as UO/sub 2/(SCN)/sub/.

SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

DOEpatents

Callis, C.F.; Moore, R.L.

1959-09-01

>The separation of ruthenium from aqueous solutions containing uranium plutonium, ruthenium, and fission products is described. The separation is accomplished by providing a nitric acid solution of plutonium, uranium, ruthenium, and fission products, oxidizing plutonium to the hexavalent state with sodium dichromate, contacting the solution with a water-immiscible organic solvent, such as hexone, to extract plutonyl, uranyl, ruthenium, and fission products, reducing with sodium ferrite the plutonyl in the solvent phase to trivalent plutonium, reextracting from the solvent phase the trivalent plutonium, ruthenium, and some fission products with an aqueous solution containing a salting out agent, introducing ozone into the aqueous acid solution to oxidize plutonium to the hexavalent state and ruthenium to ruthenium tetraoxide, and volatizing off the ruthenium tetraoxide.

SE-72/AS-72 generator system based on Se extraction/ As reextraction

DOEpatents

Fassbender, Michael Ernst; Ballard, Beau D

2013-09-10

The preparation of a .sup.72Se/.sup.72As radioisotope generator involves forming an acidic aqueous solution of an irradiated alkali bromide target such as a NaBr target, oxidizing soluble bromide in the solution to elemental bromine, removing the elemental bromine, evaporating the resulting solution to a residue, removing hydrogen chloride from the residue, forming an acidic aqueous solution of the residue, adding a chelator that selectively forms a chelation complex with selenium, and extracting the chelation complex from the acidic aqueous solution into an organic phase. As the .sup.72Se generates .sup.72As in the organic phase, the .sup.72As may be extracted repeatedly from the organic phase with an aqueous acid solution.

Heterogeneous photodegradation of methylene blue with iron and tea or coffee polyphenols in aqueous solutions.

PubMed

Morikawa, Claudio Kendi; Shinohara, Makoto

2016-01-01

Recently, we developed two new Fenton catalysts using iron (Fe) and spent tea leaves or coffee grounds as raw material. In this study, Fe-to-tea or Fe-to-coffee polyphenol complexes were successfully tested as heterogeneous photo-Fenton catalysts. The photodegradation efficiency of methylene blue solutions with Fe-to-polyphenol complexes was higher than that of homogeneous iron salts in the photo-Fenton process. Furthermore, the tested Fe-to-polyphenol complexes could be reused by simply adding H2O2 to the solutions. After three sequential additions of H2O2, the conventional catalysts FeCl2·4H2O and FeCl3 removed only 16.6% and 53.6% of the dye, while the catalysts made using spent coffee grounds and tea leaves removed 94.4% and 96.0% of the dye, respectively. These results showed that the complexes formed between Fe and chlorogenic acid, caffeic acid, gallic acid and catechin, which are the main polyphenols in tea and coffee, can be used to improve the photo-Fenton process.

Chitosan-silica complex membranes from sulfonic acid functionalized silica nanoparticles for pervaporation dehydration of ethanol-water solutions.

PubMed

Liu, Ying-Ling; Hsu, Chih-Yuan; Su, Yu-Huei; Lai, Juin-Yih

2005-01-01

Nanosized silica particles with sulfonic acid groups (ST-GPE-S) were utilized as a cross-linker for chitosan to form a chitosan-silica complex membranes, which were applied to pervaporation dehydration of ethanol-water solutions. ST-GPE-S was obtained from reacting nanoscale silica particles with glycidyl phenyl ether, and subsequent sulfonation onto the attached phenyl groups. The chemical structure of the functionalized silica was characterized with FTIR, (1)H NMR, and energy-dispersive X-ray. Homogeneous dispersion of the silica particles in chitosan was observed with electronic microscopies, and the membranes obtained were considered as nanocomposites. The silica nanoparticles in the membranes served as spacers for polymer chains to provide extra space for water permeation, so as to bring high permeation rates to the complex membranes. With addition of 5 parts per hundred of functionalized silica into chitosan, the resulting membrane exhibited a separation factor of 919 and permeation flux of 410 g/(m(2) h) in pervaporation dehydration of 90 wt % ethanol aqueous solution at 70 degrees C.

Methods and systems for utilizing carbide lime or slag

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

Devenney, Martin; Fernandez, Miguel; Chen, Irvin

Provided herein are methods comprising a) treating a slag solid or carbide lime suspension with an ammonium salt in water to produce an aqueous solution comprising calcium salt, ammonium salt, and solids; b) contacting the aqueous solution with carbon dioxide from an industrial process under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant aqueous solution wherein the precipitation material and the supernatant aqueous solution comprise residual ammonium salt; and c) removing and optionally recovering ammonia and/or ammonium salt using one or more steps of (i) recovering a gas exhaust stream comprising ammoniamore » during the treating and/or the contacting step; (ii) recovering the residual ammonium salt from the supernatant aqueous solution; and (iii) removing and optionally recovering the residual ammonium salt from the precipitation material.« less

Effect of four different size reduction methods on the particle size, solubility enhancement and physical stability of nicergoline nanocrystals.

PubMed

Martena, Valentina; Shegokar, Ranjita; Di Martino, Piera; Müller, Rainer H

2014-09-01

Nicergoline, a poorly soluble active pharmaceutical ingredient, possesses vaso-active properties which causes peripheral and central vasodilatation. In this study, nanocrystals of nicergoline were prepared in an aqueous solution of polysorbate 80 (nanosuspension) by using four different laboratory scale size reduction techniques: high pressure homogenization (HPH), bead milling (BM) and combination techniques (high pressure homogenization followed by bead milling HPH + BM, and bead milling followed by high pressure homogenization BM + HPH). Nanocrystals were investigated regarding to their mean particles size, zeta potential and particle dissolution. A short term physical stability study on nanocrystals stored at three different temperatures (4, 20 and 40 °C) was performed to evaluate the tendency to change in particle size, aggregation and zeta potential. The size reduction technique and the process parameters like milling time, number of homogenization cycles and pressure greatly affected the size of nanocrystals. Among the techniques used, the combination techniques showed superior and consistent particle size reduction compared to the other two methods, HPH + BM and BM + HPH giving nanocrystals of a mean particle size of 260 and 353 nm, respectively. The particle dissolution was increased for any nanocrystals samples, but it was particularly increased by HPH and combination techniques. Independently to the production method, nicergoline nanocrystals showed slight increase in particle size over the time, but remained below 500 nm at 20 °C and refrigeration conditions.

Unique role of ionic liquid [bmin][BF 4] during curcumin-surfactant association and micellization of cationic, anionic and non-ionic surfactant solutions

NASA Astrophysics Data System (ADS)

Patra, Digambara; Barakat, Christelle

2011-09-01

Hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroburate, modified the properties of aqueous surfactant solutions associated with curcumin. Because of potential pharmaceutical applications as an antioxidant, anti-inflammatory and anti-carcinogenic agent, curcumin has received ample attention as potential drug. The interaction of curcumin with various charged aqueous surfactant solutions showed it exists in deprotonated enol form in surfactant solutions. The nitro and hydroxyl groups of o-nitrophenol interact with the carbonyl and hydroxyl groups of the enol form of curcumin by forming ground state complex through hydrogen bonds and offered interesting information about the nature of the interactions between the aqueous surfactant solutions and curcumin depending on charge of head group of the surfactant. IL[bmin][BF 4] encouraged early formation of micelle in case of cationic and anionic aqueous surfactant solutions, but slightly prolonged micelle formation in the case of neutral aqueous surfactant solution. However, for curcumin IL [bmin][BF 4] favored strong association (7-fold increase) with neutral surfactant solution, marginally supported association with anionic surfactant solution and discouraged (˜2-fold decrease) association with cationic surfactant solution.

Fabrication of cellulose nanocrystal from Carex meyeriana Kunth and its application in the adsorption of methylene blue.

PubMed

Yang, Xue; Liu, Hui; Han, Fuyi; Jiang, Shuai; Liu, Lifang; Xia, Zhaopeng

2017-11-01

Cellulose nanocrystal (CNC) was extracted from Carex meyeriana Kunth (CMK) by a combination of TEMPO oxidation and mechanical homogenization method, and used to remove methylene blue (MB) from aqueous solution. After alkali-oxygen treatment, the aqueous biphasic system (polyethylene glycol/inorganic salt) was applied to further remove lignin from CMK. The characteriazation of CNC, and the effects of H 2 O 2 dosage, CNC dosage, adsorption time, and initial MB concentration on the MB removal capacity of CNC were investigated. The results showed that the removal percentage of MB by CNC was raised with the increase of H 2 O 2 and CNC dosage. The adsorption kinetics of prepared CNC followed the pseudo-second-order model, and the adsorption isotherms fitted well to the Langmuir model with a calculated maximum adsoption capacity of 217.4mg/g, which was higher than those of CNC extracted by acid hydrolysis method, indicating CNC extracted from CMK had promising potentials in the field of MB adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biologically Inspired Purification and Dispersion of SWCNTs

NASA Technical Reports Server (NTRS)

Feeback, Daniel L.; Clarke, Mark S.; Nikolaev, Pavel

2009-01-01

A biologically inspired method has been developed for (1) separating single-wall carbon nanotubes (SWCNTs) from other materials (principally, amorphous carbon and metal catalysts) in raw production batches and (2) dispersing the SWCNTs as individual particles (in contradistinction to ropes and bundles) in suspension, as required for a number of applications. Prior methods of purification and dispersal of SWCNTs involve, variously, harsh physical processes (e.g., sonication) or harsh chemical processes (e.g., acid reflux). These processes do not completely remove the undesired materials and do not disperse bundles and ropes into individual suspended SWCNTs. Moreover, these processes cut long SWCNTs into shorter pieces, yielding typical nanotube lengths between 150 and 250 nm. In contrast, the present method does not involve harsh physical or chemical processes. The method involves the use of biologically derived dispersal agents (BDDAs) in an aqueous solution that is mechanically homogenized (but not sonicated) and centrifuged. The dense solid material remaining after centrifugation is resuspended by vortexing in distilled water, yielding an aqueous suspension of individual, separated SWCNTs having lengths from about 10 to about 15 microns.

Aqueous chemical growth of alpha-Fe2O3-alpha-Cr203 nanocompositethin films

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

Vayssieres, Lionel; Guo, Jinghua; Nordgren, Joseph

2001-06-30

We are reporting here on the inexpensive fabrication and optical properties of an iron(III) oxide chromium(III) oxide nanocomposite thin film of corundum crystal structure. Its novel and unique-designed architecture consists of uniformed, well-defined and oriented nanorods of Hematite (alpha-Fe2O3) of 50 nm in diameter and 500nm in length and homogeneously distributed nonaggregated monodisperse spherical nanoparticles of Eskolaite (alpha-Cr2O3) of 250 nm in diameter. This alpha-Fe2O3 alpha-Cr2O3 nanocomposite thin film is obtained by growing, directly onto transparent polycrystalline conducting substrate, an oriented layer of hematite nanorods and growing subsequently, the eskolaite layer. The synthesis is carried out by a template-free, low-temperature,more » multilayer thin film coating process using aqueous solution of metal salts as precursors. Almost 100 percent of the light is absorbed by the composite film between 300 and 525 nm and 40 percent at 800 nm which yields great expectations as photoanode materials for photovoltaic cells and photocatalytic devices.« less

Potential application of aqueous two-phase systems and three-phase partitioning for the recovery of superoxide dismutase from a clarified homogenate of Kluyveromyces marxianus.

PubMed

Simental-Martínez, Jesús; Rito-Palomares, Marco; Benavides, Jorge

2014-01-01

Superoxide dismutase (SOD; EC 1.15.1.1) is an antioxidant enzyme that represents the primary cellular defense against superoxide radicals and has interesting applications in the medical and cosmetic industries. In the present work, the partition behavior of SOD in aqueous two-phase systems (ATPS) (using a standard solution and a complex extract from Kluyveromyces marxianus as sample) was characterized on different types of ATPS (polymer-polymer, polymer-salt, alcohol-salt, and ionic liquid (IL)-salt). The systems composed of PEG 3350-potassium phosphate, 45% TLL, 0.5 M NaCl (315 U/mg, 87% recovery, and 15.1-fold purification) and t-butanol-20% ammonium sulfate (205.8 U/mg, 80% recovery and 9.8-fold purification), coupled with a subsequent 100 kDa ultrafiltration stage, allowed the design of a prototype process for the recovery and partial purification of the product of interest. The findings reported herein demonstrate the potential of PEG-salt ATPS for the potential recovery of SOD. © 2014 American Institute of Chemical Engineers.

Sustainable Energy-Storage Materials from Lignin-Graphene Nanocomposite-Derived Porous Carbon Film

DOE PAGES

Tran, Chau D.; Ho, Hoi Chun; Keum, Jong K.; ...

2017-05-30

We present a simple, green approach to fabricating porous free-standing carbon films. An alkaline solution of low-cost, renewable lignin and graphene oxide (GO) is cast, followed by simultaneous carbonization and activation. Lignin, which is the least valued product from several biomass processing industries, is an efficient source of carbon when used as an intercalating agent to separate graphene sheets derived from homogeneous GO/lignin nanocomposite films prepared from an aqueous alkaline (KOH) solution. After thermal treatment the GO/lignin films show complete dispersion of reduced GO sheets within amorphous lignin-derived carbon. Furthermore, the presence of KOH in the film produces activated carbon.more » The resulting activated carbon films display a specific surface area of up to 1744 m2 g 1 and consist of a balance of pore volumes with pore sizes below and above 1 nm. A two-electrode supercapacitor composed of these films in an aqueous electrolyte exhibits near-ideal capacitive behavior at an ultrahigh scan rate of 1 V s 1, while maintaining an excellent specific capacitance of 162 F g 1. Such outstanding performance of renewable carbon as a supercapacitor, in addition to the ease of electrode fabrication from a precursor containing 85 % lignin, offers a novel method for valorization of lignin-rich byproduct streams from biomass processing industries.« less

Sustainable Energy-Storage Materials from Lignin-Graphene Nanocomposite-Derived Porous Carbon Film

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

Tran, Chau D.; Ho, Hoi Chun; Keum, Jong K.

We present a simple, green approach to fabricating porous free-standing carbon films. An alkaline solution of low-cost, renewable lignin and graphene oxide (GO) is cast, followed by simultaneous carbonization and activation. Lignin, which is the least valued product from several biomass processing industries, is an efficient source of carbon when used as an intercalating agent to separate graphene sheets derived from homogeneous GO/lignin nanocomposite films prepared from an aqueous alkaline (KOH) solution. After thermal treatment the GO/lignin films show complete dispersion of reduced GO sheets within amorphous lignin-derived carbon. Furthermore, the presence of KOH in the film produces activated carbon.more » The resulting activated carbon films display a specific surface area of up to 1744 m2 g 1 and consist of a balance of pore volumes with pore sizes below and above 1 nm. A two-electrode supercapacitor composed of these films in an aqueous electrolyte exhibits near-ideal capacitive behavior at an ultrahigh scan rate of 1 V s 1, while maintaining an excellent specific capacitance of 162 F g 1. Such outstanding performance of renewable carbon as a supercapacitor, in addition to the ease of electrode fabrication from a precursor containing 85 % lignin, offers a novel method for valorization of lignin-rich byproduct streams from biomass processing industries.« less

Highly conducting and crystalline doubly doped tin oxide films fabricated using a low-cost and simplified spray technique

NASA Astrophysics Data System (ADS)

Ravichandran, K.; Muruganantham, G.; Sakthivel, B.

2009-11-01

Doubly doped (simultaneous doping of antimony and fluorine) tin oxide films (SnO 2:Sb:F) have been fabricated by employing an inexpensive and simplified spray technique using perfume atomizer from aqueous solution of SnCl 2 precursor. The structural studies revealed that the films are highly crystalline in nature with preferential orientation along the (2 0 0) plane. It is found that the size of the crystallites of the doubly doped tin oxide films is larger (69 nm) than that (27 nm) of their undoped counterparts. The dislocation density of the doubly doped film is lesser (2.08×10 14 lines/m 2) when compared with that of the undoped film (13.2×10 14 lines/m 2), indicating the higher degree of crystallinity of the doubly doped films. The SEM images depict that the films are homogeneous and uniform. The optical transmittance in the visible range and the optical band gap of the doubly doped films are 71% and 3.56 eV respectively. The sheet resistance (4.13 Ω/□) attained for the doubly doped film in this study is lower than the values reported for spray deposited fluorine or antimony doped tin oxide films prepared from aqueous solution of SnCl 2 precursor (without using methanol or ethanol).

In situ STM investigation of aromatic poly(azomethine) arrays constructed by "on-site" equilibrium polymerization.

PubMed

Tanoue, Ryota; Higuchi, Rintaro; Ikebe, Kiryu; Uemura, Shinobu; Kimizuka, Nobuo; Stieg, Adam Z; Gimzewski, James K; Kunitake, Masashi

2012-10-02

Two-dimensional (2D) arrays of π-conjugated aromatic polymers produced by surface-selective Schiff base coupling reactions between an aromatic diamine and an aromatic dialdehyde were investigated in detail using in situ scanning tunneling microscopy. Surface-selective coupling was achieved for almost all diamine/dialdehyde combinations attempted, although several combinations did not proceed even in homogeneous aqueous alkaline solution. Most of the combinations of an aromatic diamine and a dialdehyde, except the combinations of 4,4'-azodianiline with mono/bithiophenedicarboxaldehyde, formed highly ordered π-conjugated polymer arrays on an iodine-modified Au(111) surface in aqueous solution at a suitable pH. The simplest polymer of the various combinations tested, obtained from the combination of 1,4-diaminobenzene with terephthaldicarboxaldehyde, gave a 2D array consisting of linearly connected benzene units. Poly(azomethine) adlayers caused a positive shift in the electrochemical potential of the butterfly shaped oxidative adsorption and reductive desorption of iodine. The acceleration of the reductive desorption of iodine suggests the existence of a weak interaction between the polymer layer and iodine. Not only the first polymer adlayers but also partially adsorbed secondary adlayers with "on-top" epitaxial behavior were frequently observed for all polymer systems. The alignment of the polymer chains in the adlayers possessed a certain regularity in terms of a regular interval between polymer chains because of repulsive interpolymer interactions.

Treatment of infectious skin defects or ulcers with electrolyzed strong acid aqueous solution.

PubMed

Sekiya, S; Ohmori, K; Harii, K

1997-01-01

A chronic ulcer with an infection such as methicillin-resistant Staphylococcus aureus is hard to heal. Plastic and reconstructive surgeons often encounter such chronic ulcers that are resistant to surgical or various conservative treatments. We applied conservative treatment using an electrolyzed strong acid aqueous solution and obtained satisfactory results. The lesion was washed with the solution or soaked in a bowl of the solution for approximately 20 min twice a day. Fresh electrolyzed strong acid aqueous solution is unstable and should be stored in a cool, dark site in a sealed bottle. It should be used within a week after it has been produced. Here we report on 15 cases of infectious ulcers that were treated by electrolyzed strong acid aqueous solution. Of these cases, 7 patients were healed, 3 were granulated, and in 5, infection subsided. In most cases the lesion became less reddish and less edematous. Discharge or foul odor from the lesion was decreased. Electrolyzed strong acid aqueous solution was especially effective for treating a chronic refractory ulcer combined with diabetes melitus or peripheral circulatory insufficiency. This clinically applied therapy of electrolyzed strong acid aqueous solution was found to be effective so that this new therapeutic technique for ulcer treatment can now be conveniently utilized.

Grafting of activated carbon cloths for selective adsorption

NASA Astrophysics Data System (ADS)

Gineys, M.; Benoit, R.; Cohaut, N.; Béguin, F.; Delpeux-Ouldriane, S.

2016-05-01

Chemical functionalization of an activated carbon cloth with 3-aminophthalic acid and 4-aminobenzoic acid groups by the in situ formation of the corresponding diazonium salt in aqueous acidic solution is reported. The nature and amount of selected functions on an activated carbon surface, in particular the grafted density, were determined by potentiometric titration, elemental analysis and X-ray photoelectron spectroscopy (XPS). The nanotextural properties of the modified carbon were explored by gas adsorption. Functionalized activated carbon cloth was obtained at a discrete grafting level while preserving interesting textural properties and a large porous volume. Finally, the grafting homogeneity of the carbon surface and the nature of the chemical bonding were investigated using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) technique.

Tunable Properties of Exfoliated Polyvinylalcohol Nanocomposites by In Situ Coprecipitation of Layered Double Hydroxides

NASA Astrophysics Data System (ADS)

Liu, Jiajia; Yuen, Richard K. K.; Hu, Yuan

2017-10-01

Poly(vinyl alcohol) (PVA) nanocomposites were prepared by a “one step” method based on the coprecipitation of layered double hydroxide (LDH) nanosheets in the polymer aqueous solution. The morphology, fire resistance properties, mechanical and optical properties of the PVA/LDH nanocomposites were studied. The LDH nanosheets were homogeneously dispersed in the PVA matrix as indicated by X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) characterization. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) were decreased by 58% and 28%, respectively. Storage modulus at 30 °C was increased, and the transmittance of more than 90% at the visible region was obtained upon addition of 5 wt% LDH.

Preparing polymeric matrix composites using an aqueous slurry technique

NASA Technical Reports Server (NTRS)

Johnston, Norman J. (Inventor); Towell, Timothy W. (Inventor)

1993-01-01

An aqueous process was developed to prepare a consolidated composite laminate from an aqueous slurry. An aqueous poly(amic acid) surfactant solution was prepared by dissolving a poly(amic acid) powder in an aqueous ammonia solution. A polymeric powder was added to this solution to form a slurry. The slurry was deposited on carbon fiber to form a prepreg which was dried and stacked to form a composite laminate. The composite laminate was consolidated using pressure and was heated to form the polymeric matrix. The resulting composite laminate exhibited high fracture toughness and excellent consolidation.

Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions

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

Walker, Rachel L.; Searles, Keith; Willard, Jesse A.

2013-12-28

Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphologymore » allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.« less

Synthesis of hydrothermally reduced graphene/MnO2 composites and their electrochemical properties as supercapacitors

NASA Astrophysics Data System (ADS)

Li, Zhangpeng; Wang, Jinqing; Liu, Sheng; Liu, Xiaohong; Yang, Shengrong

2011-10-01

Hydrothermally reduced graphene/MnO2 (HRG/MnO2) composites were synthesized by dipping HRG into the mixed aqueous solution of 0.1 M KMnO4 and 0.1 M K2SO4 for different periods of time at room temperature. The morphology and microstructure of the as-prepared composites were characterized by field-emission scanning electron microscopy, X-ray diffraction, Raman microscope, and X-ray photoelectron spectroscopy. The characterizations indicate that MnO2 successfully deposited on HRG surfaces and the morphology of the HRG/MnO2 shows a three-dimensional porous structure with MnO2 homogenously distributing on the HRG surfaces. Capacitive properties of the synthesized composite electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 1 M Na2SO4 aqueous solution as electrolyte. The main results of electrochemical tests are drawn as follows: the specific capacitance value of HRG/MnO2-200 (HRG dipped into the mixed solution of 0.1 M KMnO4 and 0.1 M K2SO4 for 200 min) electrode reached 211.5 F g-1 at a potential scan rate of 2 mV s-1; moreover, this electrode shows a good cyclic stability and capacity retention. It is anticipated that the synthesized HRG/MnO2 composites will find promising applications in supercapacitors and other devices in virtue of their outstanding characters of good cycle stability, low cost and environmentally benign nature.

Self-Recognition Between Two Almost Identical Macroions During Their Assembly: The Effects of pH and Temperature.

PubMed

Haso, Fadi; Li, Dong; Garai, Somenath; Pigga, Joseph M; Liu, Tianbo

2015-09-14

Two Keplerate-type macroions, [Mo(VI) 72 Fe(III) 30 O252 - (CH3 COO)12 {Mo2 O7 (H2 O)}2 {H2 Mo2 O8 (H2 O)}(H2 O)91 ]⋅ca. 150 H2 O= {Mo72 Fe30 } and [{Na(H2 O)12 }⊂{Mo(VI) 72 Cr(III) 30 O252 (CH3 COO)19 - (H2 O)94 }]⋅ca. 120 H2 O={Mo72 Cr30 }, with identical size and shape but different charge density, can self-assemble into spherical "blackberry"-like structures in aqueous solution by means of electrostatic interactions. These two macroanions can self-recognize each other and self-assemble into two separate types of homogeneous blackberries in their mixed dilute aqueous solution, in which they carry -7 and -5 net charges, respectively. Either adjusting the solution pH or raising temperature is expected to make the self-recognition more difficult, by making the charge densities of the two clusters closer, or by decreasing the activation energy barrier for the blackberry formation, respectively. Amazingly, the self-recognition behavior remains, as confirmed by dynamic and static light scattering, TEM, and energy dispersive spectroscopy techniques. The results prove that the self-recognition behavior of the macroions due to the long-range electrostatic interaction is universal and can be achieved when only minimum differences exist between two types of macroanions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Insights into water-mediated ion clustering in aqueous CaSO4 solutions: pre-nucleation cluster characteristics studied by ab initio calculations and molecular dynamics simulations.

PubMed

Li, Hui-Ji; Yan, Dan; Cai, Hou-Qin; Yi, Hai-Bo; Min, Xiao-Bo; Xia, Fei-Fei

2017-05-10

The molecular structure of growth units building crystals is a fundamental issue in the crystallization processes from aqueous solutions. In this work, a systematic investigation of pre-nucleation clusters and their hydration characteristics in aqueous CaSO 4 solutions was performed using ab initio calculations and molecular dynamics (MD) simulations. The results of ab initio calculations and MD simulations indicate that the dominant species in aqueous CaSO 4 solutions are monodentate ion-associated structures. Compared with charged ion clusters, neutral clusters are more likely to be present in an aqueous CaSO 4 solution. Neutral (CaSO 4 ) m clusters are probably the growth units involved in the pre-nucleation or crystallization processes. Meanwhile, hydration behavior around ion associated species in aqueous CaSO 4 solutions plays an important role in related phase/polymorphism selections. Upon ion clustering, the residence of some water molecules around Ca 2+ in ion-associated species is weakened while that of some bridging waters is enhanced due to dual interaction by Ca 2+ and SO 4 2- . Some phase/polymorphism selections can be achieved in aqueous CaSO 4 solutions by controlling the hydration around pre-nucleation clusters. Moreover, the association trend between calcium and sulfate is found to be relatively strong, which hints at the low solubility of calcium sulfate in water.

Salty popcorn in a homogeneous low-dimensional toy model of holographic QCD

NASA Astrophysics Data System (ADS)

Elliot-Ripley, Matthew

2017-04-01

Recently, a homogeneous ansatz has been used to study cold dense nuclear matter in the Sakai-Sugimoto model of holographic QCD. To justify this homogeneous approximation we here investigate a homogeneous ansatz within a low-dimensional toy version of Sakai-Sugimoto to study finite baryon density configurations and compare it to full numerical solutions. We find the ansatz corresponds to enforcing a dyon salt arrangement in which the soliton solutions are split into half-soliton layers. Within this ansatz we find analogues of the proposed baryonic popcorn transitions, in which solutions split into multiple layers in the holographic direction. The homogeneous results are found to qualitatively match the full numerical solutions, lending confidence to the homogeneous approximations of the full Sakai-Sugimoto model. In addition, we find exact compact solutions in the high density, flat space limit which demonstrate the existence of further popcorn transitions to three layers and beyond.

Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica

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

Szajna-Fuller, Ewa; Huang, Yulin; Rapp, Jennifer L.

2009-03-09

A comparative study of catalytic activity under homogeneous and heterogeneous conditions was carried out using the (salen)Cr{sup III}-catalyzed oxidation of tetramethylbenzidine (TMB) with iodosobenzene as a model reaction. Amine-functionalized mesoporous silica nanoparticles (MSN) were synthesized in a co-condensation reaction and functionalized with salen via a covalent Si-C bond. A Cr(III) complex of this supported ligand, MSN-(salen)Cr{sup III}, was prepared and characterized. Data from powder XRD, BET isotherms and BJH pore size distribution all showed that MSN-(salen)Cr{sup III} still had the typical MSN high surface area, narrow pore size distribution, and ordered hexagonal pore structure, which were further confirmed by transmissionmore » electron microscopy (TEM) images. {sup 13}C and {sup 29}Si solid-state NMR data provided structural information about the catalyst and verified successful functionalization of the salen ligand and coordination to Cr(III). No unreacted salen or Cr(III) were observed. The loadings of salen and salen-Cr{sup III} complex were determined via TGA and EDX, respectively. Both measurements indicated that approximately 0.5 mmol/g of catalyst was loaded on the surface of MSN. The oxidation of TMB with iodosobenzene using MSN-(salen)Cr{sup III} as a heterogeneous catalyst exhibited both similarities and differences with the analogous homogeneous reaction using (salen)Cr{sup III}(H{sub 2}O){sup +} as a catalyst in aqueous acetonitrile. In the presence of 0.10 M HClO{sub 4}, the two catalytic reactions proceeded at similar rates and generated the doubly oxidized product TMB{sup 2+}. In the absence of acid, the radical cation TMB{sup +} was produced. The kinetics of the heterogeneous reaction in the absence of added acid responded to concentrations of all three reagents, i.e. (salen)Cr{sup III}, TMB, and PhIO.« less

[Analysis of parameters of serum concentration and pharmacokinetic of liposome and aqueous solution of toatal ginsenoside of ginseng stems and leaves in rats].

PubMed

Zha, Lin; Zhao, Yan; Zhu, Hong-Yan; Cai, En-Bo; Liu, Shuang-Li; Yang, He; Zhao, Ying; Gao, Yu-Gang; Zhang, Lian-Xue

2017-05-01

The experiment was aimed to investigate the difference of plasma concentration and pharmacokinetic parameters between liposome and aqueous solution of toatal ginsenoside of ginseng stems and leaves in rats, such as ginsenosides Rg₁, Re, Rf, Rb₁, Rg₂, Rc, Rb₂, Rb₃, Rd. After intravenous injection of liposome and aqueous solution in rats, the blood was taken from the femoral vein to detect the plasma concentration of the above 9 ginsenoside monomers in different time points by using HPLC. The concentration-time curve was obtained and 3p97 pharmacokinetic software was used to get the pharmacokinetic parameters. After the intravenous injection of ginsenosides to rats, nine ginsenosides were detected in plasma. In general, among these ginsenosides, the peak time of the aqueous solution was between 0.05 to 0.083 3 h, and the serum concentration peak of liposome usually appeared after 0.5 h. After software fitting, the aqueous solution of ginsenoside monomers Rg₁, Re, Rf, Rg₂, Rc, Rd, Rb₃ was two-compartment model, and the liposomes were one-compartment model; aqueous solution and liposome of ginsenoside monomers Rb₁ were three-compartment model; aqueous solution of ginsenoside monomers Rb₂ was three-compartment model, and its liposome was one-compartment model. Area under the drug time curve (AUC) of these 9 kinds of saponin liposomes was larger than that of aqueous solution, and the retention time of the liposomes was longer than that of the aqueous solution; the removal rate was slower than that of the aqueous solution, and the half-life was longer than that of the water solution. The results from the experiment showed that by intravenous administration, the pharmacokinetic parameters of two formulations were significantly different from each other; the liposomes could not only remain the drug for a longer time in vivo, but also reduce the elimination rate and increase the treatment efficacy. As compared with the traditional dosage forms, the total ginsenoside of ginseng stems and leaves can improve the sustained release of the drug, which is of great significance for the research and development of new dosage forms of ginsenosides in the future. Copyright© by the Chinese Pharmaceutical Association.

Thermodynamic properties of potassium chloride aqueous solutions

NASA Astrophysics Data System (ADS)

Zezin, Denis; Driesner, Thomas

2017-04-01

Potassium chloride is a ubiquitous salt in natural fluids, being the second most abundant dissolved salt in many geological aqueous solutions after sodium chloride. It is a simple solute and strong electrolyte easily dissociating in water, however the thermodynamic properties of KCl aqueous solutions were never correlated with sufficient accuracy for a wide range of physicochemical conditions. In this communication we propose a set of parameters for a Pitzer-type model which allows calculation of all necessary thermodynamic properties of KCl solution, namely excess Gibbs free energy and derived activity coefficient, apparent molar enthalpy, heat capacity and volume, as well as osmotic coefficient and activity of water in solutions. The system KCl-water is one of the best studied aqueous systems containing electrolytes. Although extensive experimental data were collected for thermodynamic properties of these solutions over the years, the accurate volumetric data became available only recently, thus making possible a complete thermodynamic formulation including a pressure dependence of excess Gibbs free energy and derived properties of the KCl-water liquids. Our proposed model is intended for calculation of major thermodynamic properties of KCl aqueous solutions at temperatures ranging from freezing point of a solution to 623 K, pressures ranging from saturated water vapor up to 150 MPa, and concentrations up to the salt saturation. This parameterized model will be further implemented in geochemical software packages and can facilitate the calculation of aqueous equilibrium for reactive transport codes.

Extracting alcohols from aqueous solutions. [USDOE patent application

DOEpatents

Compere, A.L.; Googin, J.M.; Griffith, W.L.

1981-12-02

The objective is to provide an efficient process for extracting alcohols in aqueous solutions into hydrocarbon fuel mixtures, such as gasoline, diesel fuel and fuel oil. This is done by contacting an aqueous fermentation liquor with a hydrocarbon or hydrocarbon mixture containing carbon compounds having 5-18 carbon atoms, which may include gasoline, diesel fuel or fuel oil. The hydrocarbon-aqueous alcohol solution is then mixed with one or more of a group of polyoxyalkylene polymers to extract the alcohol into the hydrocarbon fuel-polyoxyalkylene polymer mixture.

Exploratory studies on some electrochemical cell systems

NASA Astrophysics Data System (ADS)

Chaudhuri, Srikumar; Guha, D.

Exploratory studies were conducted on cell systems with different metal anodes, and iodine and sulphur mixed with graphite powder in a polymer matrix as cathodes, using different electrolytes in non-aqueous and aqueous media as ionic charge carriers. The electrical conductance of the electrolyte solutions in aqueous and non-aqueous solvents, the open circuit voltage (OCV) and short circuit current (SCC) for the different cell systems were measured. To date, the non-aqueous solvents used in our studies were dimethylformamide, formamide, dioxan, and nitrobenzene, and the electrolytes used were potassium iodide, caustic potash, cetyltrimethylammonium bromide (CTAB), sodium lauryl sulphate (SLS) and calcium chloride. These electrolytes were used in both non-aqueous and aqueous media. In general, aqueous electrolyte solutions gave a better performance than non-aqueous electrolyte solutions. Of the aqueous electrolytes, the highest conductance was shown by potassium chloride solution in water (conductance=0.0334 mho). However, the best OCV and SCC were shown by aluminium as anode and iodine as cathode with a saturated solution of caustic potash in water. The OCV was 1.85 V and the SCC was 290 mA cm -2. The highest conductance among the non-aqueous systems was shown by caustic potash in formamide. (Conductance=0.013 mho.) The best OCV and SCC, however, were shown by a zinc anode and iodine cathode with saturated potassium chloride in formamide, having an OCV of 1.55 V and an SCC of 150 mA cm -2. Further studies are in progress to obtain detailed performance data and recharging characteristics of some of the more promising systems reported here.

Modeling polychlorinated biphenyl mass transfer after amendment of contaminated sediment with activated carbon.

PubMed

Werner, David; Ghosh, Upal; Luthy, Richard G

2006-07-01

The sorption kinetics and concentration of polychlorinated biphenyls (PCBs) in historically polluted sediment is modeled to assess a remediation strategy based on in situ PCB sequestration by mixing with activated carbon (AC). We extend our evaluation of a model based on intraparticle diffusion by including a biomimetic semipermeable membrane device (SPMD) and a first-order degradation rate for the aqueous phase. The model predictions are compared with the previously reported experimental PCB concentrations in the bulk water phase and in SPMDs. The simulated scenarios comprise a marine and a freshwater sediment, four PCB congeners, two AC grain sizes, four doses of AC, and comparison with laboratory experiments for up to 540 days of AC amendment slowly mixed with sediment. The model qualitatively reproduces the observed shifts in the PCB distribution during repartitioning after AC amendment but systematically overestimates the overall effect of the treatment in reducing aqueous and SPMD concentrations of PCBs by a factor of 2-6. For our AC application in sediment, competitive sorption of the various solutes apparently requires a reduction by a factor of 16 of the literature values for the AC-water partitioning coefficient measured in pure aqueous systems. With this correction, model results and measurements agree within a factor of 3. We also discuss the impact of the nonlinearity of the AC sorption isotherm and first-order degradation in the aqueous phase. Regular mixing of the sediment accelerates the benefit of the proposed amendment substantially. But according to our scenario, after AC amendment is homogeneously mixed into the sediment and then left undisturbed, aqueous PCB concentrations tend toward the same reduction after approximately 5 or more years.

Contact efflorescence as a pathway for crystallization of atmospherically relevant particles

PubMed Central

Davis, Ryan D.; Lance, Sara; Gordon, Joshua A.; Ushijima, Shuichi B.; Tolbert, Margaret A.

2015-01-01

Inadequate knowledge of the phase state of atmospheric particles represents a source of uncertainty in global climate and air quality models. Hygroscopic aqueous inorganic particles are often assumed to remain liquid throughout their atmospheric lifetime or only (re)crystallize at low relative humidity (RH) due to the kinetic limitations of efflorescence (salt crystal nucleation and growth from an aqueous solution). Here we present experimental observations of a previously unexplored heterogeneous nucleation pathway that we have termed “contact efflorescence,” which describes efflorescence initiated by an externally located solid particle coming into contact with the surface of a metastable aqueous microdroplet. This study demonstrates that upon a single collision, contact efflorescence is a pathway for crystallization of atmospherically relevant aqueous particles at high ambient RH (≤80%). Soluble inorganic crystalline particles were used as contact nuclei to induce efflorescence of aqueous ammonium sulfate [(NH4)2SO4], sodium chloride (NaCl), and ammonium nitrate (NH4NO3), with efflorescence being observed in several cases close to their deliquescence RH values (80%, 75%, and 62%, respectively). To our knowledge, these observations represent the highest reported efflorescence RH values for microdroplets of these salts. These results are particularly important for considering the phase state of NH4NO3, where the contact efflorescence RH (∼20–60%) is in stark contrast to the observation that NH4NO3 microdroplets do not homogeneously effloresce, even when exposed to extremely arid conditions (<1% RH). Considering the occurrence of particle collisions in the atmosphere (i.e., coagulation), these observations of contact efflorescence challenge many assumptions made about the phase state of inorganic aerosol. PMID:26668396

Contact efflorescence as a pathway for crystallization of atmospherically relevant particles.

PubMed

Davis, Ryan D; Lance, Sara; Gordon, Joshua A; Ushijima, Shuichi B; Tolbert, Margaret A

2015-12-29

Inadequate knowledge of the phase state of atmospheric particles represents a source of uncertainty in global climate and air quality models. Hygroscopic aqueous inorganic particles are often assumed to remain liquid throughout their atmospheric lifetime or only (re)crystallize at low relative humidity (RH) due to the kinetic limitations of efflorescence (salt crystal nucleation and growth from an aqueous solution). Here we present experimental observations of a previously unexplored heterogeneous nucleation pathway that we have termed "contact efflorescence," which describes efflorescence initiated by an externally located solid particle coming into contact with the surface of a metastable aqueous microdroplet. This study demonstrates that upon a single collision, contact efflorescence is a pathway for crystallization of atmospherically relevant aqueous particles at high ambient RH (≤80%). Soluble inorganic crystalline particles were used as contact nuclei to induce efflorescence of aqueous ammonium sulfate [(NH4)2SO4], sodium chloride (NaCl), and ammonium nitrate (NH4NO3), with efflorescence being observed in several cases close to their deliquescence RH values (80%, 75%, and 62%, respectively). To our knowledge, these observations represent the highest reported efflorescence RH values for microdroplets of these salts. These results are particularly important for considering the phase state of NH4NO3, where the contact efflorescence RH (∼20-60%) is in stark contrast to the observation that NH4NO3 microdroplets do not homogeneously effloresce, even when exposed to extremely arid conditions (<1% RH). Considering the occurrence of particle collisions in the atmosphere (i.e., coagulation), these observations of contact efflorescence challenge many assumptions made about the phase state of inorganic aerosol.

SEPARATION OF PLUTONIUM FROM AQUEOUS SOLUTIONS BY ION-EXCHANGE

DOEpatents

Schubert, J.

1958-06-01

A process is described for the separation of plutonium from an aqueous solution of a plutonium salt, which comprises adding to the solution an acid of the group consisting of sulfuric acid, phosphoric acid, and oxalic acid, and mixtures thereof to provide an acid concentration between 0.0001 and 1 M, contacting the resultant solution with a synthetic organic anion exchange resin, and separating the aqueous phase and the resin which contains the plutonium.

A study on lithium/air secondary batteries-Stability of the NASICON-type lithium ion conducting solid electrolyte in alkaline aqueous solutions

NASA Astrophysics Data System (ADS)

Shimonishi, Yuta; Zhang, Tao; Imanishi, Nobuyuki; Im, Dongmin; Lee, Dong Joon; Hirano, Atsushi; Takeda, Yasuo; Yamamoto, Osamu; Sammes, Nigel

The stability of the high lithium ion conducting glass ceramics, Li 1+ x+ yTi 2- xAl xSi yP 3- yO 12 (LTAP) in alkaline aqueous solutions with and without LiCl has been examined. A significant conductivity decrease of the LTAP plate immersed in 0.057 M LiOH aqueous solution at 50 °C for 3 weeks was observed. However, no conductivity change of the LTAP plate immersed in LiCl saturated LiOH aqueous solutions at 50 °C for 3 weeks was observed. The pH value of the LiCl-LiOH-H 2O solution with saturated LiCl was in a range of 7-9. The molarity of LiOH and LiCl in the LiOH and LiCl saturated aqueous solution were estimated to be 5.12 and 11.57 M, respectively, by analysis of Li + and OH -. The high concentration of LiOH and the low pH value of 8.14 in this solution suggested that the dissociation of LiOH into Li + and OH - is too low in the solution with a high concentration of Li +. These results suggest that the water stable LTAP could be used as a protect layer of the lithium metal anode in the lithium/air cell with LiCl saturated aqueous solution as the electrolyte, because the content of OH - ions in the LiCl saturated aqueous solution does not increase via the cell reaction of Li + 1/2O 2 + H 2O → 2LiOH, and LTAP is stable under a deep discharge state.

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

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

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactantmore » fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.« less

Environment-Friendly Post-Treatment of PEDOT-Tos Films by Aqueous Vitamin C Solutions for Tuning of Thermoelectric Properties

NASA Astrophysics Data System (ADS)

Khan, Ezaz Hasan; Thota, Sammaiah; Wang, Yiwen; Li, Lian; Wilusz, Eugene; Osgood, Richard; Kumar, Jayant

2018-04-01

Aqueous vitamin C solution has been used as an environment-friendly reducing agent for tuning the thermoelectric properties of p-toluenesulfonate-doped poly(3,4-ethylenedioxythiophene) (PEDOT-Tos) films. The de-doping of the PEDOT-Tos films by aqueous vitamin C solutions led to a decrease in the electrical conductivity of the films. The measured ultraviolet-visible-near-infrared and x-ray photoelectron spectra clearly indicated the reduction in the oxidation level from 37 to 23% when the PEDOT-Tos films were treated with 5% (w/v) aqueous vitamin C solutions. An increase in the Seebeck coefficient was measured, resulting in an increase in the figure-of-merit (ZT). A 42% increase in ZT was determined for the 5% aqueous vitamin C solution-treated PEDOT-Tos films with respect to that of the untreated films.

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-08-11

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

Application of Molecular Dynamics Simulations in Molecular Property Prediction II: Diffusion Coefficient

PubMed Central

Wang, Junmei; Hou, Tingjun

2011-01-01

In this work, we have evaluated how well the General AMBER force field (GAFF) performs in studying the dynamic properties of liquids. Diffusion coefficients (D) have been predicted for 17 solvents, 5 organic compounds in aqueous solutions, 4 proteins in aqueous solutions, and 9 organic compounds in non-aqueous solutions. An efficient sampling strategy has been proposed and tested in the calculation of the diffusion coefficients of solutes in solutions. There are two major findings of this study. First of all, the diffusion coefficients of organic solutes in aqueous solution can be well predicted: the average unsigned error (AUE) and the root-mean-square error (RMSE) are 0.137 and 0.171 ×10−5 cm−2s−1, respectively. Second, although the absolute values of D cannot be predicted, good correlations have been achieved for 8 organic solvents with experimental data (R2 = 0.784), 4 proteins in aqueous solutions (R2 = 0.996) and 9 organic compounds in non-aqueous solutions (R2 = 0.834). The temperature dependent behaviors of three solvents, namely, TIP3P water, dimethyl sulfoxide (DMSO) and cyclohexane have been studied. The major MD settings, such as the sizes of simulation boxes and with/without wrapping the coordinates of MD snapshots into the primary simulation boxes have been explored. We have concluded that our sampling strategy that averaging the mean square displacement (MSD) collected in multiple short-MD simulations is efficient in predicting diffusion coefficients of solutes at infinite dilution. PMID:21953689

Aqueous Phase Synthesis of CuIn Alloy Nanoparticles and Their Application for a CIS (CuInSe2)-Based Printable Solar Battery

PubMed Central

Takahashi, Hideyuki; Fujiki, Hironari; Yokoyama, Shun; Kai, Takayuki; Tohji, Kazuyuki

2018-01-01

To apply CuInSe2 (CIS)-based printable solar batteries; an aqueous phase synthesis method of Cu-In (CI) alloy nanoparticles is studied. Metal complexes in the original solution are restricted to homogenized species by utilizing calculations. For example; [(Cu2+)(ASP2−)2] [ASP: the “body (C4H5O4N)” of aspartic acid (C4H7O4N)] is predominant in the pH 6–13 region (CASP/CCu > 6); while In complexes can be restricted to [(In3+)(OH−)(EDTA4−)] (pH 10–12; CEDTA/CIn = 2) and/or [(In3+)(ASP2−)2] (pH 7–9; CASP/CIn = 5). These results indicate that the added amount of complex reagents should be determined by calculations and not the stoichiometric ratio. The reduction potential of homogenized metal complex is measured by cyclic voltammetry (CV) measurements and evaluated by Nernst’s equation using the overall stability constants. CuIn alloy nanoparticles with a small amount of byproduct (In nanoparticles) are successfully synthesized. The CI precursor films are spin-coated onto the substrate using a 2-propanol dispersion. Then the films are converted into CIS solar cells; which show a maximum conversion efficiency of 2.30%. The relationship between the open circuit potential; short circuit current density; and fill factor indicate that smoothing of the CIS films and improving the crystallinity and thickness increase the solar cell conversion efficiency. PMID:29642413

Microencapsulation of nanoemulsions: novel Trojan particles for bioactive lipid molecule delivery

PubMed Central

Li, Xiang; Anton, Nicolas; Ta, Thi Minh Chau; Zhao, Minjie; Messaddeq, Nadia; Vandamme, Thierry F

2011-01-01

Background Nanoemulsions consist of very stable nanodroplets of oil dispersed in an aqueous phase, typically below 300 nm in size. They can be used to obtain a very fine, homogeneous dispersion of lipophilic compounds in water, thus facilitating their handling and use in nanomedicine. However, the drawback is that they are suspended in an aqueous media. This study proposes a novel technique for drying lipid nanoemulsion suspensions to create so-called Trojan particles, ie, polymer microparticles (around 2 μm) which very homogeneously “entrap” the nano-oil droplets (around 150 nm) in their core. Methods Microencapsulation of the nanoemulsions was performed using a spray-drying process and resulted in a dried powder of microparticles. By using a low-energy nanoemulsification method and relatively gentle spray-drying, the process was well suited to sensitive molecules. The model lipophilic molecule tested was vitamin E acetate, encapsulated at around 20% in dried powder. Results We showed that the presence of nanoemulsions in solution before spray-drying had a significant impact on microparticle size, distribution, and morphology. However, the process itself did not destroy the oil nanodroplets, which could easily be redispersed when the powder was put back in contact with water. High-performance liquid chromatography follow-up of the integrity of the vitamin E acetate showed that the molecules were intact throughout the process, as well as when conserved in their dried form. Conclusion This study proposes a novel technique using a spray-drying process to microencapsulate nanoemulsions. The multiscale object formed, so-called Trojan microparticles, were shown to successfully encapsulate, protect, and release the lipid nanodroplets. PMID:21760727

Unravelling the pH-dependence of a molecular photocatalytic system for hydrogen production.

PubMed

Reynal, Anna; Pastor, Ernest; Gross, Manuela A; Selim, Shababa; Reisner, Erwin; Durrant, James R

2015-08-01

Photocatalytic systems for the reduction of aqueous protons are strongly pH-dependent, but the origin of this dependency is still not fully understood. We have studied the effect of different degrees of acidity on the electron transfer dynamics and catalysis taking place in a homogeneous photocatalytic system composed of a phosphonated ruthenium tris(bipyridine) dye ( RuP ) and a nickel bis(diphosphine) electrocatalyst ( NiP ) in an aqueous ascorbic acid solution. Our approach is based on transient absorption spectroscopy studies of the efficiency of photo-reduction of RuP and NiP correlated with pH-dependent photocatalytic H 2 production and the degree of catalyst protonation. The influence of these factors results in an observed optimum photoactivity at pH 4.5 for the RuP - NiP system. The electron transfer from photo-reduced RuP to NiP is efficient and independent of the pH value of the medium. At pH <4.5, the efficiency of the system is limited by the yield of RuP photo-reduction by the sacrificial electron donor, ascorbic acid. At pH >4.5, the efficiency of the system is limited by the poor protonation of NiP , which inhibits its ability to reduce protons to hydrogen. We have therefore developed a rational strategy utilising transient absorption spectroscopy combined with bulk pH titration, electrocatalytic and photocatalytic experiments to disentangle the complex pH-dependent activity of the homogenous RuP - NiP photocatalytic system, which can be widely applied to other photocatalytic systems.

Microencapsulation of nanoemulsions: novel Trojan particles for bioactive lipid molecule delivery.

PubMed

Li, Xiang; Anton, Nicolas; Ta, Thi Minh Chau; Zhao, Minjie; Messaddeq, Nadia; Vandamme, Thierry F

2011-01-01

Nanoemulsions consist of very stable nanodroplets of oil dispersed in an aqueous phase, typically below 300 nm in size. They can be used to obtain a very fine, homogeneous dispersion of lipophilic compounds in water, thus facilitating their handling and use in nanomedicine. However, the drawback is that they are suspended in an aqueous media. This study proposes a novel technique for drying lipid nanoemulsion suspensions to create so-called Trojan particles, ie, polymer microparticles (around 2 μm) which very homogeneously "entrap" the nano-oil droplets (around 150 nm) in their core. Microencapsulation of the nanoemulsions was performed using a spray-drying process and resulted in a dried powder of microparticles. By using a low-energy nanoemulsification method and relatively gentle spray-drying, the process was well suited to sensitive molecules. The model lipophilic molecule tested was vitamin E acetate, encapsulated at around 20% in dried powder. We showed that the presence of nanoemulsions in solution before spray-drying had a significant impact on microparticle size, distribution, and morphology. However, the process itself did not destroy the oil nanodroplets, which could easily be redispersed when the powder was put back in contact with water. High-performance liquid chromatography follow-up of the integrity of the vitamin E acetate showed that the molecules were intact throughout the process, as well as when conserved in their dried form. This study proposes a novel technique using a spray-drying process to microencapsulate nanoemulsions. The multiscale object formed, so-called Trojan microparticles, were shown to successfully encapsulate, protect, and release the lipid nanodroplets.

Cobinamide production of hydrogen in a homogeneous aqueous photochemical system, and assembly and photoreduction in a (βα)8 protein

PubMed Central

Robertson, Wesley D.; Bovell, Adonis M.; Warncke, Kurt

2013-01-01

Components of a protein-integrated, earth-abundant metal-macrocycle catalyst, purposed for hydrogen (H2) production from aqueous protons under green conditions, are characterized. The cobalt (Co) -corrin complex, cobinamide, is demonstrated to produce H2 (4.4±1.8×10−3 turnover number per hour) in a homogeneous, photosensitizer/sacrificial electron donor system, in pure water at neutral pH. Turnover is proposed to be limited by the relatively low population of the gateway Co(III) hydride species. A heterolytic mechanism for H2 production from the Co(II) hydride is proposed. Two essential requirements for assembly of a functional protein catalyst complex are demonstrated, for interaction of cobinamide with the (βα)8, TIM-barrel protein, EutB, from the adenosylcobalamin-dependent ethanolamine ammonia-lyase from Salmonella typhimurium: (1) High affinity equilibrium binding of the cobinamide (dissociation constant, 2.1×10−7 M), and (2) in situ photoreduction of the cobinamide-protein complex to the Co(I) state. Molecular modeling of the cobinamide-EutB interaction shows that these features arise from specific hydrogen bond and apolar interactions of the protein with the alkylamide substituents and ring of the corrin, and accessibility of the binding site to solution. The results establish cobinamide-EutB as a platform for design and engineering of a robust H2 production metallo-catalyst, that operates under green conditions, and utilizes advantages of protein as a tunable medium and material support. PMID:23807763

Electrophotolysis oxidation system for measurement of organic concentration in water

NASA Technical Reports Server (NTRS)

Winkler, H. E. (Inventor)

1981-01-01

Methods and apparatus for determining organic carbon in aqueous solution are described. The method comprises subjecting the aqueous solution to electrolysis, for generating oxygen from water, and simultaneously to ultraviolet radiation, for oxidation of substantially all organic carbon to carbon dioxide. The carbon dioxide is measured and the value is related to the concentration of organic carbon in the aqueous solution.

RECOVERY AND SEPARATION OF LITHIUM VALUES FROM SALVAGE SOLUTIONS

DOEpatents

Hansford, D.L.; Raabe, E.W.

1963-08-20

Lithium values can be recovered from an aqueous basic solution by reacting the values with a phosphate salt soluble in the solution, forming an aqueous slurry of the resultant aqueous insoluble lithium phosphate, contacting the slurry with an organic cation exchange resin in the acid form until the slurry has been clarified, and thereafter recovering lithium values from the resin. (AEC)

Prediction of the glass transition in aqueous solutions of simple amides by molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Kreck, Cara A.; Mandumpal, Jestin B.; Mancera, Ricardo L.

2011-01-01

Some simple amides in aqueous solution are used in the cryopreservation of biological tissues as they are believed to promote the vitrification of water, inhibiting its crystallisation and the ensuing damage from ice formation. Molecular dynamics annealing simulations reveal a broadening in the glass transition of aqueous acetamide and N-methylacetamide solutions, suggesting a thermodynamic stabilisation of the glassy state, which may be responsible for their increased tendency of vitrification and their cryoprotective ability. By contrast, aqueous formamide solutions do not exhibit broadening of the glass transition; instead, it is shifted to lower temperatures, which explains their lack of vitrification properties.

Study of thermodynamic and acoustic behaviour of nicotinic acid in binary aqueous mixtures of D-lactose

NASA Astrophysics Data System (ADS)

Sharma, Ravi; Thakur, R. C.

2017-07-01

In the present study, the thermodynamic properties such as partial molar volumes, partial molar expansibilities, partial molar compressibilities, partial molar heat capacities and isobaric thermal expansion coefficient of different solutions of nicotinic acid in binary aqueous mixtures of D-lactose have been determined at different temperatures (298.15, 303.15, 308.15, 313.15) K. Masson's equation is used to interpret the data in terms of solute-solute and solute-solvent interactions. In the present study it has been found that nicotinic acid behaves as structure maker in aqueous and binary aqueous mixtures of D-lactose.

Ultrafast fluorescence quenching dynamics of Atto655 in the presence of N-acetyltyrosine and N-acetyltryptophan in aqueous solution: proton-coupled electron transfer versus electron transfer.

PubMed

Zhang, Ying; Yuan, Shuwei; Lu, Rong; Yu, Anchi

2013-06-20

We studied the ultrafast fluorescence quenching dynamics of Atto655 in the presence of N-acetyltyrosine (AcTyr) and N-acetyltryptophan (AcTrp) in aqueous solution with femtosecond transient absorption spectroscopy. We found that the charge-transfer rate between Atto655 and AcTyr is about 240 times smaller than that between Atto655 and AcTrp. The pH value and D2O dependences of the excited-state decay kinetics of Atto655 in the presence of AcTyr and AcTrp reveal that the quenching of Atto655 fluorescence by AcTyr in aqueous solution is via a proton-coupled electron-transfer (PCET) process and that the quenching of Atto655 fluorescence by AcTrp in aqueous solution is via an electron-transfer process. With the version of the semiclassical Marcus ET theory, we derived that the electronic coupling constant for the PCET reaction between Atto655 and AcTyr in aqueous solution is 8.3 cm(-1), indicating that the PCET reaction between Atto655 and AcTyr in aqueous solution is nonadiabatic.

Method and apparatus for synthesizing anhydrous HNO.sub.3

DOEpatents

Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.; McGuire, Raymond R.

1984-01-01

A method and apparatus for electrochemically synthesizing anhydrous HNO.sub.3 from an aqueous solution of HNO.sub.3 includes oxidizing a solution of N.sub.2 O.sub.4 /aqueous HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /aqueous HNO.sub.3 solution and the anode. A potential of about 1.80V vs. SCE is preferred. Anhydrous or aqueous HNO.sub.3 may be disposed at the cathode within the electrochemical cell. Aqueous HNO.sub.3 having a water content of up to about 12% by weight is utilized to synthesize anhydrous HNO.sub.3.

Method and apparatus for synthesizing anhydrous HNO/sub 3/. [Patent application

DOEpatents

Coon, C.L.; Harrar, J.E.; Pearson, R.K.; McGuire, R.R.

1982-07-20

A method and apparatus for electrochemically synthesizing anhydrous HNO/sub 3/ from an aqueous solution of HNO/sub 3/- includes oxidizing a solution of N/sub 2/O/sub 4//aqueous HNO/sub 3/ at an anode, while maintaining a controlled potential between the N/sub 2/O/sub 4//aqueous HNO/sub 3/ solution and the anode. A potential of about 1.80V vs. SCE is preferred. Anhydrous or aqueous HNO/sub 3/ may be disposed at the cathode within the electrochemical cell. Aqueous HNO/sub 3/ having a water content of up to about 12% by weight is utilized to synthesize anhydrous HNO/sub 3/.

Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water

PubMed Central

Zhao, Li-Shan; Cao, Ze-Xian; Wang, Qiang

2015-01-01

Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, . Here we report a universal water-content, , dependence of for aqueous solutions. Solutions with vitrify/devitrify at a constant temperature, , referring to freeze-concentrated phase with left behind ice crystallization. Those solutions with totally vitrify at under conventional cooling/heating process though, of the samples annealed at temperatures   to effectively evoke ice recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of by annealing is attributable to freeze-concentrated phase of solutions instead of ‘liquid II phase of water’. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution. PMID:26503911

Physico-chemical properties of aqueous drug solutions: From the basic thermodynamics to the advanced experimental and simulation results.

PubMed

Bellich, Barbara; Gamini, Amelia; Brady, John W; Cesàro, Attilio

2018-04-05

The physical chemical properties of aqueous solutions of model compounds are illustrated in relation to hydration and solubility issues by using three perspectives: thermodynamic, spectroscopic and molecular dynamics simulations. The thermodynamic survey of the fundamental backgrounds of concentration dependence and experimental solubility results show some peculiar behavior of aqueous solutions with several types of similar solutes. Secondly, the use of a variety of experimental spectroscopic devices, operating under different experimental conditions of dimension and frequency, has produced a large amount of structural and dynamic data on aqueous solutions showing the richness of the information produced, depending on where and how the experiment is carried out. Finally, the use of molecular dynamics computational work is presented to highlight how the different types of solute functional groups and surface topologies organize adjacent water molecules differently. The highly valuable contribution of computer simulation studies in providing molecular explanations for experimental deductions, either of a thermodynamic or spectroscopic nature, is shown to have changed the current knowledge of many aqueous solution processes. While this paper is intended to provide a collective view on the latest literature results, still the presentation aims at a tutorial explanation of the potentials of the three methodologies in the field of aqueous solutions of pharmaceutical molecules. Copyright © 2018. Published by Elsevier B.V.

Catalytic wet air oxidation of aniline with nanocasted Mn-Ce-oxide catalyst.

PubMed

Levi, R; Milman, M; Landau, M V; Brenner, A; Herskowitz, M

2008-07-15

The catalytic wet air oxidation of aqueous solution containing 1000 ppm aniline was conducted in a trickle-bed reactor packed with a novel nanocasted Mn-Ce-oxide catalyst (surface area of 300 m2/g) prepared using SBA-15 silica as a hard template. A range of liquid hourly space velocities (5-20 h(-1)) and temperatures (110-140 degrees C) at 10 bar of oxygen were tested. The experiments were conducted to provide the intrinsic performance of the catalysts. Complete aniline conversion, 90% TOC conversion, and 80% nitrogen mineralization were achieved at 140 degrees C and 5 h(-1). Blank experiments yielded relatively low homogeneous aniline (<35%) and negligible TOC conversions. Fast deactivation of the catalysts was experienced due to leaching caused by complexation with aniline. Acidification of the solution with HCI (molar HCI to aniline ratio of 1.2) was necessary to avoid colloidization and leaching of the nanoparticulate catalyst components. The catalyst displayed stable performance for over 200 h on stream.

Electrochemical advanced oxidation processes: today and tomorrow. A review.

PubMed

Sirés, Ignasi; Brillas, Enric; Oturan, Mehmet A; Rodrigo, Manuel A; Panizza, Marco

2014-01-01

In recent years, new advanced oxidation processes based on the electrochemical technology, the so-called electrochemical advanced oxidation processes (EAOPs), have been developed for the prevention and remediation of environmental pollution, especially focusing on water streams. These methods are based on the electrochemical generation of a very powerful oxidizing agent, such as the hydroxyl radical ((•)OH) in solution, which is then able to destroy organics up to their mineralization. EAOPs include heterogeneous processes like anodic oxidation and photoelectrocatalysis methods, in which (•)OH are generated at the anode surface either electrochemically or photochemically, and homogeneous processes like electro-Fenton, photoelectro-Fenton, and sonoelectrolysis, in which (•)OH are produced in the bulk solution. This paper presents a general overview of the application of EAOPs on the removal of aqueous organic pollutants, first reviewing the most recent works and then looking to the future. A global perspective on the fundamentals and experimental setups is offered, and laboratory-scale and pilot-scale experiments are examined and discussed.

Applications of β-limit dextrin as a matrix forming excipient for fast disintegrating buccal dosage formats.

PubMed

Qi, Xin; Tester, Richard; Liu, Yu; Mullin, Margaret

2012-01-01

To compare the properties of buccal delivery matrices (wafers) made with dextrin, β-limit dextrin and pre-gelatinised starch. The constituent α-glucans were tested for their mucoadhesive properties in solution plus their content of crystalline material (differential scanning calorimetry, DSC). Wafers were made by lyophilisation of aqueous solutions/dispersions of the α-glucans. Physical properties of the wafers were evaluated using texture analysis, dissolution coupled to photography and scanning electron microscopy (SEM). The results highlighted how the β-limit dextrins chemical and physical properties were ideally suited for the production of buccal delivery wafers. Dissolution testing confirmed the excellent hydration profile of the β-limit dextrin (within wafers) with time. Using SEM it was evident that the homogeneous "bee-hive" like structure of the β-limit dextrin wafers, unlike the other α-glucans, provided a rapidly hydratable strong porous matrix. The β-limit dextrin α-glucan makes a superb (lyophilised) mucoadhesive delivery structure for the delivery of active agents to the buccal mucosa.

Adsorption of Ni(II) onto Chemically Modified Spent Grated Coconut (Cocos Nucifera)

NASA Astrophysics Data System (ADS)

Hamzah, F. I.; Khalid, K.; Hanafiah, M. A. K. M.

2017-06-01

A new adsorbent of plant waste origin from coconut processing food factory was explored for removing Ni(II) from aqueous solutions. Several parameters such as pH, dosage, concentration and contact time were studied to obtain optimum conditions for treatment of Ni(II) contaminated wastewater. Spent grated coconut (Cocos nucifera) treated with sulfuric acid (SSGC) showed good adsorption capacity for Ni(II) ion. The amount adsorbed was affected by solution pH with the highest value achieved at pH 5. Other optimum conditions found were; dosage of 0.02 g, and 60 min of equilibrium time. Ni(II) adsorption obeyed the pseudo-second order kinetic model which suggested that chemisorption mechanism occurred in the adsorption process. The equilibrium data presented a better fitting to the Langmuir isotherm model, an indication that monolayer adsorption occurred onto a homogeneous surface. The maximum adsorption capacity, qmax was 97.09 mg g-1, thus SSGC can be classified as good and comparable with other plant waste adsorbents.

Sol-gel synthesis of fine Gd{sub 2}CuO{sub 4} particles: Influence of synthesis variables

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

Mahia, J.; Vazquez-Vazquez, C.; Basadre-Pampin, M.I.

1996-02-01

Fine particles of Gd{sub 2}CuO{sub 4} were prepared by a sol-gel reaction of an aqueous solution of metal nitrates in the presence of urea, which leads to high-homogeneity polycrystalline powders of Gd{sub 2}CuO{sub 4}. The authors have studied the synthesis conditions, demonstrating the existence of a relationship between the calcination temperature and the heating time needed to attain the pure phase. Gd{sub 2}CuO{sub 4} was obtained at temperatures of the order of 650 C, lower than temperatures employed in the conventional ceramic technique. The influence of the [urea]/[salts] ratio and an excess of Cu(II) in the starting solution was alsomore » studied and discussed. X-ray powder diffraction inductively coupled plasma atomic emission spectroscopy (ICPAES), photon correlation spectroscopy (PCS), and transmission electron microscopy (TEM) were used to characterize the Gd{sub 2}CuO{sub 4} samples obtained.« less

Aluminate effect on desilication product phase transformation

NASA Astrophysics Data System (ADS)

Peng, Hong; Vaughan, James

2018-06-01

It remains a grand challenge in the treatment of bauxite residue to physically separate zeolite (also known as the DeSilication Product, DSP) from other unleached mineral phases owing to their fine sizes, typically less than 2 μm in diameter. In this study, the effect of aluminate concentration on DSP phase transformation was investigated from synthetic NaOH-NaAl(OH)4-Na2SiO3-H2O solution at 90 °C. The results show how at relatively low aluminate concentrations of 0.125 and 0.25 M NaAl(OH)4(aq), larger zeolite crystals of up to 60 μm in diameter are formed during homogenous precipitation from aqueous solution. The precipitation process involves the conversion of zeolite LTA to sodalite via the formation of an intermediate phase, octahedral LTN. Initial amorphous solids precipitate as aggregates in which cubic zeolite LTA nucleation occurs. As the reaction proceeds, truncated octahedral LTN appears with the cubic zeolite LTA and finally sodalite crystallizes on the LTA-LTN aggregates resulting in coarsened particles.

Enzymatic production and in situ separation of natural β-ionone from β-carotene.

PubMed

Nacke, Christoph; Hüttmann, Sonja; Etschmann, Maria M W; Schrader, Jens

2012-12-01

A biotechnological process concept for generation and in situ separation of natural β-ionone from β-carotene is presented. The process employs carotenoid cleavage dioxygenases (CCDs), a plant-derived iron-containing nonheme enzyme family requiring only dissolved oxygen as cosubstrate and no additional cofactors. Organophilic pervaporation was found to be very well suited for continuous in situ separation of β-ionone. Its application led to a highly pure product despite the complexity of the reaction solution containing cell homogenates. Among three different pervaporation membrane types tested, a polyoctylmethylsiloxane active layer on a porous polyetherimide support led to the best results. A laboratory-scale demonstration plant was set up, and a highly pure aqueous-ethanolic solution of β-ionone was produced from β-carotene. The described process permits generation of high-value flavor and fragrance compounds bearing the desired label "natural" according to US and European food and safety regulations and demonstrates the potential of CCD enzymes for selective oxidative cleavage of carotenoids.

Assorted interactions of amino acids prevailing in aqueous vitamin C solutions probed by physicochemical and ab-initio contrivances

NASA Astrophysics Data System (ADS)

Das, Koyeli; Roy, Milan Chandra; Rajbanshi, Biplab; Roy, Mahendra Nath

2017-11-01

Qualitative and quantitative analysis of molecular interaction prevailing in tyrosine and tryptophan in aqueous solution of vitamin C have been probed by thermophysical properties. The apparent molar volume (ϕV), viscosity B-coefficient, molal refraction (RM) of tyrosine and tryptophan have been studied in aqueous vitamin C solutions at diverse temperatures via Masson equation which deduced solute-solvent and solute-solute interactions, respectively. Spectroscopic study along with physicochemical and computational techniques provides lots of interesting and highly significant insights of the model biological systems. The overall results established strong solute-solvent interactions between studied amino acids and vitamin C mixture in the ternary solutions.

URANIUM DECONTAMINATION WITH RESPECT TO ZIRCONIUM

DOEpatents

Vogler, S.; Beederman, M.

1961-05-01

A process is given for separating uranium values from a nitric acid aqueous solution containing uranyl values, zirconium values and tetravalent plutonium values. The process comprises contacting said solution with a substantially water-immiscible liquid organic solvent containing alkyl phosphate, separating an organic extract phase containing the uranium, zirconium, and tetravalent plutonium values from an aqueous raffinate, contacting said organic extract phase with an aqueous solution 2M to 7M in nitric acid and also containing an oxalate ion-containing substance, and separating a uranium- containing organic raffinate from aqueous zirconium- and plutonium-containing extract phase.

PROCESS OF SEPARATING URANIUM FROM AQUEOUS SOLUTION BY SOLVENT EXTRACTION

DOEpatents

Warf, J.C.

1958-08-19

A process is described for separating uranium values from aqueous uranyl nitrate solutions. The process consists in contacting the uramium bearing solution with an organic solvent, tributyl phosphate, preferably diluted with a less viscous organic liquida whereby the uranyl nitrate is extracted into the organic solvent phase. The uranvl nitrate may be recovered from the solvent phase bv back extracting with an aqueous mediuin.

In Situ Cross-Linking of Polyvinyl Alcohol Films

NASA Technical Reports Server (NTRS)

Philipp, W. H.; Shu, L. C.; May, C. E.

1984-01-01

Films or impregnated matrices readily made from aqueous polyvinyl alcohol solution. Controlled thickness films made by casting precise quantities of aqueous polymer solution on smooth surface, allowing water to evaporate and then removing film. Composite separators formed in similar fashion by impregnating cloth matrix with polyvinyl alcohol solution and drying composite. Insoluble thin hydrophilic membranes made from aqueous systems, and use of undesirable organic solvents not required.

Sediment Ecosystem Assessment Protocol (SEAP): An Accurate and Integrated Weight-of-Evidence Based System

DTIC Science & Technology

2011-01-01

polychaete Neanthes arenaceodentata from exposures to copper in aqueous solutions ...involved 96 h exposures in aqueous solutions , followed by a 1-2 hour (depending on size) feeding period on Artemia (brine shrimp) nauplii in clean seawater...EC50) based on post- exposure feeding of the polychaete Neanthes arenaceodentata from exposures to copper in aqueous solutions . Metric (µg/L) Worm age

Synthesis and Characterization of Functional Mesostructures Using Colloidal Crystal Templating

DTIC Science & Technology

2004-01-01

fluorescent probes in aqueous polymer solutions . Khoury and co-workers measured the diffusion coefficient of several fluorescein-labeled proteins in...diffraction naq refractive index of the aqueous solution phase xvii ni refractive index of component i ngel refractive index of the hydrogel...phase Tg glass transition temperature α angle of diffraction φaq volume fraction of the aqueous solution phase φi volume fraction of

SOLVENT EXTRACTION OF THORIUM VALUES FROM AQUEOUS SOLUTIONS

DOEpatents

Warf, J.C.

1959-04-21

The separation of thorium values from rare earth metals contained ln aqueous solutions by means of extraction with a water immiscible alkyl phosphate diluted with a hydrocarbon such as hexane is described. While the extraction according to this invention may be carried out from any aqueous salt solution, it is preferred to use solutions containing free mineral acid. Hydrochloric acid and in particular nitric acid are sultable in a concentration ranging from 0.1 to 7 normal. The higher acid concentration results in higher extraction values.

Influence of pH, temperature, and concentration on stabilization of aqueous hornet silk solution and fabrication of salt-free materials.

PubMed

Kameda, Tsunenori

2015-01-01

We found that an aqueous solution of silk from cocoons produced by hornet larvae (hornet silk) can be obtained when the solution is adjusted to basic conditions of pH > 9.2. It is known that native hornet cocoons can be dissolved in concentrated aqueous solution of salts, such as lithium bromide (LiBr) and calcium chloride (CaCl2). Upon the removal of these salts from solution by dialysis, solidification, gelation, or sedimentation of hornet silk is known to occur. In the present study, under basic conditions, however, no such solidification occurred, even after salt removal. In this study, ammonia was used for alkalization of solution because it is volatilized during the casting process and pure hornet silk materials can be obtained after drying. The effects of the concentrations of hornet silk and ammonia, as well as dialysis temperature, on preventing gelation during dialysis were investigated. Dialysis conditions that limit the degradation of hornet silk by hydrolysis in alkali solution were identified. Moreover, casting conditions to prepare flexible and transparent hornet silk film from aqueous ammonia solution were optimized. Molecular structural analysis of hornet silk in aqueous ammonia solution and cast film indicated the formation of α-helix conformations. © 2014 Wiley Periodicals, Inc.

Modified resins for solid-phase extraction

DOEpatents

Fritz, James S.; Sun, Jeffrey J.

1993-07-27

A process of treating aqueous solutions to remove organic solute contaminants by contacting an aqueous solution containing polar organic solute contaminants with a functionalized polystyrene-divinyl benzene adsorbent resin, with the functionalization of said resin being accomplished by organic hydrophilic groups such as hydroxymethyl, acetyl and cyanomethyl.

Modified resins for solid-phase extraction

DOEpatents

Fritz, James S.; Sun, Jeffrey J.

1991-12-10

A process of treating aqueous solutions to remove organic solute contaminants by contacting an aqueous solution containing polar organic solute contaminants with a functionalized polystyrene-divinyl benzene adsorbent resin, with the functionalization of said resin being accomplished by organic hydrophilic groups such as hydroxymethyl, acetyl and cyanomethyl.

URANIUM RECOVERY PROCESS

DOEpatents

Hyman, H.H.; Dreher, J.L.

1959-07-01

The recovery of uranium from the acidic aqueous metal waste solutions resulting from the bismuth phosphate carrier precipitation of plutonium from solutions of neutron irradiated uranium is described. The waste solutions consist of phosphoric acid, sulfuric acid, and uranium as a uranyl salt, together with salts of the fission products normally associated with neutron irradiated uranium. Generally, the process of the invention involves the partial neutralization of the waste solution with sodium hydroxide, followed by conversion of the solution to a pH 11 by mixing therewith sufficient sodium carbonate. The resultant carbonate-complexed waste is contacted with a titanated silica gel and the adsorbent separated from the aqueous medium. The aqueous solution is then mixed with sufficient acetic acid to bring the pH of the aqueous medium to between 4 and 5, whereby sodium uranyl acetate is precipitated. The precipitate is dissolved in nitric acid and the resulting solution preferably provided with salting out agents. Uranyl nitrate is recovered from the solution by extraction with an ether such as diethyl ether.

Diffusion of aqueous solutions of ionic, zwitterionic, and polar solutes

NASA Astrophysics Data System (ADS)

Teng, Xiaojing; Huang, Qi; Dharmawardhana, Chamila Chathuranga; Ichiye, Toshiko

2018-06-01

The properties of aqueous solutions of ionic, zwitterionic, and polar solutes are of interest to many fields. For instance, one of the many anomalous properties of aqueous solutions is the behavior of water diffusion in different monovalent salt solutions. In addition, solutes can affect the stabilities of macromolecules such as proteins in aqueous solution. Here, the diffusivities of aqueous solutions of sodium chloride, potassium chloride, tri-methylamine oxide (TMAO), urea, and TMAO-urea are examined in molecular dynamics simulations. The decrease in the diffusivity of water with the concentration of simple ions and urea can be described by a simple model in which the water molecules hydrogen bonded to the solutes are considered to diffuse at the same rate as the solutes, while the remainder of the water molecules are considered to be bulk and diffuse at almost the same rate as pure water. On the other hand, the decrease in the diffusivity of water with the concentration of TMAO is apparently affected by a decrease in the diffusion rate of the bulk water molecules in addition to the decrease due to the water molecules hydrogen bonded to TMAO. In other words, TMAO enhances the viscosity of water, while urea barely affects it. Overall, this separation of water molecules into those that are hydrogen bonded to solute and those that are bulk can provide a useful means of understanding the short- and long-range effects of solutes on water.

Method and apparatus for measuring volatile compounds in an aqueous solution

DOEpatents

Gilmore, Tyler J [Pasco, WA; Cantrell, Kirk J [West Richland, WA

2002-07-16

The present invention is an improvement to the method and apparatus for measuring volatile compounds in an aqueous solution. The apparatus is a chamber with sides and two ends, where the first end is closed. The chamber contains a solution volume of the aqueous solution and a gas that is trapped within the first end of the chamber above the solution volume. The gas defines a head space within the chamber above the solution volume. The chamber may also be a cup with the second end. open and facing down and submerged in the aqueous solution so that the gas defines the head space within the cup above the solution volume. The cup can also be entirely submerged in the aqueous solution. The second end of the. chamber may be closed such that the chamber can be used while resting on a flat surface such as a bench. The improvement is a sparger for mixing the gas with the solution volume. The sparger can be a rotating element such as a propeller on a shaft or a cavitating impeller. The sparger can also be a pump and nozzle where the pump is a liquid pump and the nozzle is a liquid spray nozzle open, to the head space for spraying the solution volume into the head space of gas. The pump could also be a gas pump and the nozzle a gas nozzle submerged in the solution volume for spraying the head space gas into the solution volume.

Comparison of cytotoxicity in vitro and irritation in vivo for aqueous and oily solutions of surfactants.

PubMed

Czajkowska-Kośnik, Anna; Wolska, Eliza; Chorążewicz, Juliusz; Sznitowska, Małgorzata

2015-01-01

The in vivo model on rabbit eyes and the in vitro cytotoxicity on fibroblasts were used to compare irritation effect of aqueous and oily (Miglyol 812) solutions of surfactants. Tween 20, Tween 80 and Cremophor EL were tested in different concentrations (0.1, 1 or 5%) and the in vitro test demonstrated that surfactants in oil are less cytotoxic than in aqueous solutions. In the in vivo study, the aqueous solutions of surfactants were characterized as non-irritant while small changes in conjunctiva were observed after application the oily solutions of surfactants and the preparations were classified as slightly irritant, however this effect was similar when Miglyol was applied alone. In conclusion, it is reported that the MTT assay does not correlate well with the Draize scores.

Dielectric study of aqueous solutions of sodium dodecyl sulfate in the frequency span 20 Hz to 2 MHz

NASA Astrophysics Data System (ADS)

Kadve, A. M.; Vankar, H. P.; Rana, V. A.

2017-05-01

Dielectric measurements were carried out for aqueous solutions of Sodium Dodecyl Sulfate (SDS) in the frequency span of 20 Hz to 2 MHz at 300.15 K temperature using precision LCR meter. Also the refractive indices were measured for the solutions at 300.15 K temperature using Abbe's refractometer. The measurements were done for ten different concentrations of SDS in distilled water. Determined values of complex permittivity as a function of frequency were used to evaluate other parameters like loss tangent and electric modulus for the liquid samples. The permittivity at optical frequency were also calculated from the measured refractive indices for the aqueous solutions. The effect of concentration variation of SDS in the aqueous solutions on the determined parameters is discussed.

Effective adsorption and collection of cesium from aqueous solution using graphene oxide grown on porous alumina

NASA Astrophysics Data System (ADS)

Entani, Shiro; Honda, Mitsunori; Shimoyama, Iwao; Li, Songtian; Naramoto, Hiroshi; Yaita, Tsuyoshi; Sakai, Seiji

2018-04-01

Graphene oxide (GO) with a large surface area was synthesized by the direct growth of GO on porous alumina using chemical vapor deposition to study the Cs adsorption mechanism in aqueous solutions. Electronic structure analysis employing in situ near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy measurements clarifies the Cs atoms bond via oxygen functional groups on GO in the aqueous solution. The Cs adsorption capacity was found to be as high as 650-850 mg g-1, which indicates that the GO/porous alumina acts as an effective adsorbent with high adsorption efficiency for radioactive nuclides in aqueous solutions.

RECOVERY OF PROTACTINIUM FROM AQUEOUS SOLUTIONS

DOEpatents

Elson, R.E.

1959-07-14

The recovery of fluoride complexed protactinium from aqueous acidic solutions by solvent extraction is described. Generally the prccess of the invention com rises mixing an aqueous solution containing protactinium in a complexed form with an organic solvent which is specific for protactinium, such as diisopropyl carbinol, then decomposing the protactinium complex by adjusting the acidity of the aqueous solution to between 0-3 to 0-9 M in hydrogen ion concentration, and introducing a source of aluminum ions in sufficient quantity to establish a concentration of 0.5 to 1.2 M aluminum ion, whereupon decomposition of the protactinium fluoride complex takes place and the protactinium ion is taken up by the organic solvent phase.

Process for recovering pertechnetate ions from an aqueous solution also containing other ions

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1997-01-01

A solid/liquid process for the separation and recovery of TcO.sub.4.sup.-1 ions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups; whereas the aqueous solution from which the TcO.sub.4.sup.-1 ions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt. A solid/liquid phase admixture of separation particles containing bound TcO.sub.4.sup.-1 ions in such an aqueous solution that is free from MoO.sub.4.sup.-2 ions is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture.

Method for selectively reducing plutonium values by a photochemical process

DOEpatents

Friedman, Horace A.; Toth, Louis M.; Bell, Jimmy T.

1978-01-01

The rate of reduction of Pu(IV) to Pu(III) in nitric acid solution containing a reducing agent is enhanced by exposing the solution to 200-500 nm electromagnetic radiation. Pu values are recovered from an organic extractant solution containing Pu(IV) values and U(VI) values by the method of contacting the extractant solution with an aqueous nitric acid solution in the presence of a reducing agent and exposing the aqueous solution to electromagnetic radiation having a wavelength of 200-500 nm. Under these conditions, Pu values preferentially distribute to the aqueous phase and U values preferentially distribute to the organic phase.

Self-dispersible nanocrystals of albendazole produced by high pressure homogenization and spray-drying.

PubMed

Paredes, Alejandro Javier; Llabot, Juan Manuel; Sánchez Bruni, Sergio; Allemandi, Daniel; Palma, Santiago Daniel

2016-10-01

Albendazole (ABZ) is a broad-spectrum antiparasitic drug used in the treatment of human or animal infections. Although ABZ has shown a high efficacy for repeated doses in monogastric mammals, its low aqueous solubility leads to erratic bioavailability. The aim of this work was to optimize a procedure in order to obtain ABZ self-dispersible nanocrystals (SDNC) by combining high pressure homogenization (HPH) and spray-drying (SD). The material thus obtained was characterized and the variables affecting both the HPH and SD processes were studied. As expected, the homogenizing pressure and number of cycles influenced the final particle size, while the stabilizer concentration had a strong impact on SD output and redispersion of powders upon contact with water. ABZ SDNC were successfully obtained with high process yield and redispersibility. The characteristic peaks of ABZ were clearly identified in the X-ray patterns of the processed samples. A noticeable increase in the dissolution rate was observed in the aqueous environment.

Thermodynamic characteristics of protolytic equilibria of L-serine in aqueous solutions

NASA Astrophysics Data System (ADS)

Kochergina, L. A.; Volkov, A. V.; Khokhlova, E. A.; Krutova, O. N.

2011-05-01

The heat effects of the reaction of aqueous solution of L-serine with aqueous solutions of HNO3 and KOH were determined by calorimetry at temperatures of 288.15, 298.15, and 308.15 K, and ionic strength values of 0.2, 0.5, and 1.0 (background electrolyte, KNO3). Standard thermodynamic characteristics (Δr H o, Δr G o, Δr S o, Δ C {/p o}) of the acid-base reactions in aqueous solutions of L-serine were calculated. The effect of the concentration of background electrolyte and temperature on the heats of dissociation of amino acid was considered. The combustion energy of L-serine by bomb calorimetry in the medium of oxygen was determined. The standard combustion and formation enthalpies of crystalline L-serine were calculated. The heats of dissolution of crystalline L-serine in water and solutions of potassium hydroxide at 298.15 K were measured by direct calorimetry. The standard enthalpies of formation of L-serine and products of its dissociation in aqueous solution were calculated.

Adsorption of aqueous copper on peanut hulls

NASA Astrophysics Data System (ADS)

Davis, Kanika Octavia

A method was established for measuring the adsorption of Cu(II) from aqueous solution to unmodified and modified peanut hulls at constant temperature and pH. Modification of the hulls was performed by oxidation with alkaline hydrogen peroxide. During the modification process, the hydrogen peroxide solubilizes the lignin component, making the surface more porous which increases the availability of binding sites, while simultaneously oxidizing the cellulose. The oxidation of alcohol groups creates more binding sites by creating functional groups such as COO-, which increases chelation to metal ions. Fourier transform infrared spectroscopy confirms delignification of the peanut hulls by the disappearance of carboxyl peaks of the modified hulls, which were originally produced from the lignin content. Although, oxidation is not fully confirmed, it is not ruled out because the expected carboxylate peak (1680 cm-1) maybe overshadowed by a broad peak due to OH bending of water adsorbed to the hulls. Hulls adsorbed copper from solutions in the concentration range of 50-1000 ppm of CuCl2. Concentrations of pre- and post-adsorption solutions were determined using inductively coupled plasma optical emission spectroscopy. The adsorption isotherms were fit to known two and three-parameter models, evaluated and the binding mechanism was inferred. Maximum surface coverage was 3.5 +/- 0.6 mg Cu2+ /g hull for unmodified hulls and 11 +/- 1 mg Cu2+/g hull for modified hulls. The adsorption for the hulls is best described by the Langmuir model, suggesting monolayer, homogeneous adsorption. With a free energy of adsorption of 10.5 +/- 0.9 kJ/mol for unmodified hulls and 14.5 +/-0.4 kJ/mol for modified hulls, the process is categorized as chemisorption for both types of hulls. The adsorption for both hulls is also described by the Redlich-Peterson model, giving beta nearer to 1 than 0, which further suggests homogeneous adsorption described by the Langmuir model. After rinsing the hulls, scanning electron microscopy images coupled with energy dispersive X-ray spectroscopy showed that the percentage of copper on the modified hulls (2.5 %) was greater than on the unmodified hulls (1.6 %). This study concluded that the adsorption of copper using peanut hulls is a potential method for wastewater treatment and delignification and oxidation of the hulls increases the adsorption capacity approximately three-fold.

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

PubMed

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

2009-09-01

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

Recovery of alkali metal constituents from catalytic coal conversion residues

DOEpatents

Soung, W.Y.

In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide to precipitate silicon constituents, the pH of the resultant solution is increased, preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

Efficient ensemble system based on the copper binding motif for highly sensitive and selective detection of cyanide ions in 100% aqueous solutions by fluorescent and colorimetric changes.

PubMed

Jung, Kwan Ho; Lee, Keun-Hyeung

2015-09-15

A peptide-based ensemble for the detection of cyanide ions in 100% aqueous solutions was designed on the basis of the copper binding motif. 7-Nitro-2,1,3-benzoxadiazole-labeled tripeptide (NBD-SSH, NBD-SerSerHis) formed the ensemble with Cu(2+), leading to a change in the color of the solution from yellow to orange and a complete decrease of fluorescence emission. The ensemble (NBD-SSH-Cu(2+)) sensitively and selectively detected a low concentration of cyanide ions in 100% aqueous solutions by a colorimetric change as well as a fluorescent change. The addition of cyanide ions instantly removed Cu(2+) from the ensemble (NBD-SSH-Cu(2+)) in 100% aqueous solutions, resulting in a color change of the solution from orange to yellow and a "turn-on" fluorescent response. The detection limits for cyanide ions were lower than the maximum allowable level of cyanide ions in drinking water set by the World Health Organization. The peptide-based ensemble system is expected to be a potential and practical way for the detection of submicromolar concentrations of cyanide ions in 100% aqueous solutions.

Process for extracting technetium from alkaline solutions

DOEpatents

Moyer, Bruce A.; Sachleben, Richard A.; Bonnesen, Peter V.

1995-01-01

A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate, the at least one alkali metal nitrate having a concentration of from about 0.1 to 6 molar. The solution is contacted with a solvent consisting of a crown ether in a diluent for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution. The solvent containing the technetium values is separated from the aqueous alkaline solution and the technetium values are stripped from the solvent.

Bidentate organophosphorus solvent extraction process for actinide recovery and partition

DOEpatents

Schulz, Wallace W.

1976-01-01

A liquid-liquid extraction process for the recovery and partitioning of actinide values from acidic nuclear waste aqueous solutions, the actinide values including trivalent, tetravalent and hexavalent oxidation states is provided and includes the steps of contacting the aqueous solution with a bidentate organophosphorous extractant to extract essentially all of the actinide values into the organic phase. Thereafter the respective actinide fractions are selectively partitioned into separate aqueous solutions by contact with dilute nitric or nitric-hydrofluoric acid solutions. The hexavalent uranium is finally removed from the organic phase by contact with a dilute sodium carbonate solution.

Adsorption of Cu(II) from aqueous solution on sulfuric acid treated palygorskite

NASA Astrophysics Data System (ADS)

Niu, Yan-Ning; Yuan, Yuan; Gao, Wei-Xin; Qian, Sheng; Sun, Wen

2018-03-01

The absorption behavior of Cu2+ from aqueous solution on sulfuric acid treated palygorskite were investigated, the results showed that palygorskite had high absorption ability for Cu2+ from aqueous solution. Effects of the shaking time, pH and the copper ion concentration on the removal rate were discussed. The absorption behavior of Cu2+ could be well imitated by the Langmuir isothermal equation.

Water purification using organic salts

DOEpatents

Currier, Robert P.

2004-11-23

Water purification using organic salts. Feed water is mixed with at least one organic salt at a temperature sufficiently low to form organic salt hydrate crystals and brine. The crystals are separated from the brine, rinsed, and melted to form an aqueous solution of organic salt. Some of the water is removed from the aqueous organic salt solution. The purified water is collected, and the remaining more concentrated aqueous organic salt solution is reused.

Structural and spectroscopic studies of a rare non-oxido V(v) complex crystallized from aqueous solution

DOE PAGES

Leggett, Christina J.; Parker, Bernard F.; Teat, Simon J.; ...

2016-01-14

A “bare” V 5+ complex with glutaroimide-dioxime (H 3L), a ligand for uranium recovery from seawater, was synthesized from aqueous solution as Na[V(L) 2]2H 2O and the structure determined by x-ray diffraction. It is the first non-oxo V(v) complex that has been directly synthesized in and crystallized from aqueous solution.

Measurement of Surface Forces

DTIC Science & Technology

1990-11-16

creating an electrical double-layer whenever a bare mica surface is in contact with an aqueous solution . The mica/electrolyte double-layer...between mica in aqueous solutions containing 10-5 to I M KNO 3 (From Reference 44. Copyright 0 1985 Royal Swedish Academy. Reprinted with permission of...can be observed in aqueous KNO 3 solutions at close separations and at high ion concentrations. For example, if the force curves in Figure 8 (top) for

Structural and spectroscopic studies of a rare non-oxido V(v) complex crystallized from aqueous solution

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

Leggett, Christina J.; Parker, Bernard F.; Teat, Simon J.

A “bare” V 5+ complex with glutaroimide-dioxime (H 3L), a ligand for uranium recovery from seawater, was synthesized from aqueous solution as Na[V(L) 2]2H 2O and the structure determined by x-ray diffraction. It is the first non-oxo V(v) complex that has been directly synthesized in and crystallized from aqueous solution.

Sorption of 4-carboxyquinoline derivatives from aqueous acetonitrile solutions on the surface of porous graphitized carbon

NASA Astrophysics Data System (ADS)

Savchenkova, A. S.; Buryak, A. K.; Kurbatova, S. V.

2015-09-01

The sorption of 4-carboxyquinoline derivatives from aqueous acetonitrile solutions on porous graphitized carbon was studied. The effect of the structure of analyte molecules and the eluent composition on the characteristics of retention under the conditions of RP HPLC was analyzed. The effect of pH of the eluent on the shift of equilibrium in aqueous acetonitrile solutions was investigated.

ADSORPTION PROCEDURE IN PREPARING U$sup 23$$sup 3$

DOEpatents

Stoughton, R.W.

1958-10-14

A process is presented for the separation of protoactinium and thorium from an aqueous nitric acid solution containing these metals. It comprises contacting the solution with a cation exchange phenol-formaldehyde resin containing sulfonic acid groups, and eluting the adsorbed thorium from the resin by means of aqueous nitric acid. Thereafter the adsorbed protoactinium is eluted from the resin by means of an aqueous solution of ammonium fluoride.

In situ, real time observation of the disintegration of paracetamol tablets in aqueous solution by magnetic resonance imaging.

PubMed

Tritt-Goc, Jadwiga; Kowalczuk, Joanna

2002-05-01

The disintegration behavior of paracetamol tablets was studied by magnetic resonance imaging (MRI) using the Snapshot FLASH method. The total time of the single experiment is 425 ms and allows the study of the disintegration process in real time. The study was carried out in vitro under acidic gastric pH conditions and may help to predict the behavior of paracetamol tablets in the stomach after oral administration. It was shown that in spite of identical conditions, the disintegration of the tablets under study was different. The distribution of protons of 4-(N-acetyl)aminophenol within the paracetamol tablet was shown to be homogeneous. The study was carried out in a non-destructive way by the SPI MRI method.

The Limits of Template-Directed Synthesis with Nucleoside-5'-Phosphoro(2-Methyl) Imidazolides

NASA Technical Reports Server (NTRS)

Hill, Aubrey R., Jr.; Orgel, Leslie E.; Wu, Taifeng

1993-01-01

In earlier work we have shown that C-rich templates containing isolated A, T or G residues and short oligo(G) sequences can be copied effectively using nucleoside-5'-phosphoro(2-methyl)imidazolides as substrates. We now show that isolated A or T residues within an oligo(G) sequence are a complete block to copying and that an isolated C residue is copied inefficiently. Replication is possible only if there are two complementary oligonucleotides each of which acts as a template to facilitate the synthesis of the other. We emphasize the severity of the problems that need to be overcome to make possible non-enzymatic replication in homogeneous aqueous solution. We conclude that an efficient catalyst was involved in the origin of polynucleotide replication.

Viscosity of Associated Mixtures Approximated by the Grunberg-Nissan Model

NASA Astrophysics Data System (ADS)

Marczak, W.; Adamczyk, N.; Łężniak, M.

2012-04-01

Previous experiments demonstrated that microheterogeneities occur in liquid systems (2-methylpyridine or 2,6-dimethylpyridine) + water. They are most probably due to the association of the hydrates through hydrogen bonds between water molecules. Substitution of methanol for water causes that the mixtures become homogenous. The results of viscometric studies reported in this study confirmed that the molecular clusters in aqueous solutions are much larger than the complexes occurring in the methanolic systems. Taking into consideration "kinetic entities" rather than monomeric molecules, the dependence of viscosity on concentration and temperature have been satisfactorily approximated by the Grunberg-Nissan relation with two adjustable coefficients. The kinetic entities were trimers of water, dimers of methanol, and monomeric amines. The same approach proved to be valid for the activation energy of viscous flow as well.

Fluid inclusion study of some Sarrabus fluorite deposits, Sardinia, Italy.

USGS Publications Warehouse

Belkin, H.E.; de Vivo, B.; Valera, R.

1984-01-01

Fluid inclusions in six deposits of fluorite fracture fillings associated with Hercynian (Carboniferous) cycle magmatism were studied by microthermometric techniques. All the inclusions were liquid dominated, aqueous, and homogenized in the liquid phase. One-phase (liquid), two-phase (liquid + vapour) and three-phase (liquid, vapour, and solid NaCl daughter mineral) fluid inclusions were noted. This study indicates that five of the fluorite deposits formed from 95o-125oC fluids with approx 15 wt.% NaCl. One other deposit appears to have been formed by very dilute solutions at approx 125oC. It is suggested that the local fluorite-forming process was the formation of fracture-localized hydrothermal systems in which magmatic water interaction with some other fluid-connate, meteoric, or marine.-G.J.N.

KDP Aqueous Solution-in-Oil Microemulsion for Ultra-Precision Chemical-Mechanical Polishing of KDP Crystal

PubMed Central

Dong, Hui; Wang, Lili; Gao, Wei; Li, Xiaoyuan; Wang, Chao; Ji, Fang; Pan, Jinlong; Wang, Baorui

2017-01-01

A novel functional KH2PO4 (KDP) aqueous solution-in-oil (KDP aq/O) microemulsion system for KDP crystal ultra-precision chemical-mechanical polishing (CMP) was prepared. The system, which consisted of decanol, Triton X-100, and KH2PO4 aqueous solution, was available at room temperature. The functional KDP aq/O microemulsion system was systematically studied and applied as polishing solution to KDP CMP technology. In this study, a controlled deliquescent mechanism was proposed for KDP polishing with the KDP aq/O microemulsion. KDP aqueous solution, the chemical etchant in the polishing process, was caged into the micelles in the microemulsion, leading to a limitation of the reaction between the KDP crystal and KDP aqueous solution only if the microemulsion was deformed under the effect of the external force. Based on the interface reaction dynamics, KDP aqueous solutions with different concentrations (cKDP) were applied to replace water in the traditional water-in-oil (W/O) microemulsion. The practicability of the controlled deliquescent mechanism was proved by the decreasing material removal rate (MRR) with the increasing of the cKDP. As a result, the corrosion pits on the KDP surface were avoided to some degree. Moreover, the roughnesses of KDP with KDP aq/O microemulsion (cKDP was changed from 10 mM to 100 mM) as polishing solutions were smaller than that with the W/O microemulsion. The smallest surface root-mean-square roughness of 1.5 nm was obtained at a 30 mmol/L KDP aq solution, because of the most appropriate deliquescent rate and MRR. PMID:28772632

KDP Aqueous Solution-in-Oil Microemulsion for Ultra-Precision Chemical-Mechanical Polishing of KDP Crystal.

PubMed

Dong, Hui; Wang, Lili; Gao, Wei; Li, Xiaoyuan; Wang, Chao; Ji, Fang; Pan, Jinlong; Wang, Baorui

2017-03-09

A novel functional KH₂PO₄ (KDP) aqueous solution-in-oil (KDP aq/O) microemulsion system for KDP crystal ultra-precision chemical-mechanical polishing (CMP) was prepared. The system, which consisted of decanol, Triton X-100, and KH₂PO₄ aqueous solution, was available at room temperature. The functional KDP aq/O microemulsion system was systematically studied and applied as polishing solution to KDP CMP technology. In this study, a controlled deliquescent mechanism was proposed for KDP polishing with the KDP aq/O microemulsion. KDP aqueous solution, the chemical etchant in the polishing process, was caged into the micelles in the microemulsion, leading to a limitation of the reaction between the KDP crystal and KDP aqueous solution only if the microemulsion was deformed under the effect of the external force. Based on the interface reaction dynamics, KDP aqueous solutions with different concentrations ( c KDP ) were applied to replace water in the traditional water-in-oil (W/O) microemulsion. The practicability of the controlled deliquescent mechanism was proved by the decreasing material removal rate (MRR) with the increasing of the c KDP . As a result, the corrosion pits on the KDP surface were avoided to some degree. Moreover, the roughnesses of KDP with KDP aq/O microemulsion ( c KDP was changed from 10 mM to 100 mM) as polishing solutions were smaller than that with the W/O microemulsion. The smallest surface root-mean-square roughness of 1.5 nm was obtained at a 30 mmol/L KDP aq solution, because of the most appropriate deliquescent rate and MRR.

Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

2016-09-01

Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

Ceramic porous material and method of making same

DOEpatents

Liu, Jun; Kim, Anthony Y.; Virden, Jud W.

1997-01-01

The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors.

Ceramic porous material and method of making same

DOEpatents

Liu, J.; Kim, A.Y.; Virden, J.W.

1997-07-08

The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors. 21 figs.

Antiscalant properties of Spergularia rubra and Parietaria officinalis aqueous solutions

NASA Astrophysics Data System (ADS)

Cheap-Charpentier, Hélène; Gelus, Dominique; Pécoul, Nathalie; Perrot, Hubert; Lédion, Jean; Horner, Olivier; Sadoun, Jonathan; Cachet, Xavier; Litaudon, Marc; Roussi, Fanny

2016-06-01

The formation of calcium carbonate in water has important implications in industry. Chemical antiscalant is usually used to control scale depositions. Plant extracts have been recently used as new green antiscalant agents, as they can be easily prepared and are environmentally friendly. In this study, stock aqueous solutions of Spergularia rubra and Parietaria officinalis, two plants used in traditional medicine to treat or prevent urolithiasis, were obtained by infusion. The antiscaling properties of these extracts towards CaCO3 formation were tested by using chronoamperometry and Fast Controlled Precipitation methods. The aqueous solution of S. rubra was further fractionated to isolate compounds of lower polarity. Their efficiency towards CaCO3 precipitation was characterized by Fast Controlled Precipitation method. The inhibiting efficiency of this fractionated solution was greater than that of the stock aqueous solution.

SEPARATION PROCESS FOR TRANSURANIC ELEMENT AND COMPOUNDS THEREOF

DOEpatents

Magnusson, L.B.

1958-04-01

A process is described for the separation of neptunium, from aqueous solutions of neptunium, plutonium, uraniunn, and fission prcducts. This separation from an acidic aqueous solution of a tetravalent neptuniunn can be made by contacting the solution with a certain type of chelating,; agent, preferably dissolved in an organic solvent, to form a neptunium chelate compound. When the organic solvent is present, the neptunium chelate compound is extracted; otherwise, it precipitates from the aqueous solution and is separated by any suitable means. The chelating agent is a fluorinated BETA -diketone. such as trifluoroacetyl acetone.

Radiolysis of aqueous solutions of thiamine

NASA Astrophysics Data System (ADS)

Chijate, C.; Albarran, G.; Negron-Mendoza, A.

1998-06-01

The results of the radiolysis of aqueous solutions of thiamine (vitamin B 1) are presented. The yields for decomposition of thiamine and the product of radiolytic products were determined. The G values decrease as the dose increases. Some radiolytic products were identified. Decomposition of thiamine was slightly dependent on the presence of oxygen and on the pH of the solution. At pH 4.4 with a concentration of 2.5 × 10 -4 mol L -1 of thiamine in an oxygen free aqueous solution, the G 0 value for decomposition is 5.0.

ION EXCHANGE PROCESS FOR THE RECOVERY AND PURIFICATION OF MATERIALS

DOEpatents

Long, R.S.; Bailes, R.H.

1958-04-15

A process for the recovery of certain metallic ions from aqueous solutions by ion exchange techniques is described. It is applicable to elements such as vanadium, chromium, nnanganese, and the like, which are capable of forming lower valent cations soluble in aqueous solutions and which also form ldgher valent anions soluble in aqueous acidic solutions. For example, small amounts of vanadium occurring in phosphoric acid prepared from phosphate rock may be recovered by reducing the vanadium to a trivalent cation adsorbing; the vanadium in a cationic exchange resin, then treating the resin with a suitable oxidizing agent to convert the adsorbed vanadium to a higher valent state, and finally eluting; the vanadium as an anion from the resin by means of an aqueous acidic solution.

Removal of copper ions from aqueous solutions by a steel-making by-product.

PubMed

López, F A; Martín, M I; Pérez, C; López-Delgado, A; Alguacil, F J

2003-09-01

A study is made of the use of a steel-making by-product (rolling mill scale) as a material for removing Cu(2+) ions from aqueous solutions. The influence of contact time, initial copper ion concentration and temperature on removal capability is considered. The removal of Cu(2+) ions from an aqueous solution involves two processes: on the one hand, the adsorption of Cu(2+) ions on the surface of mill scale due to the iron oxides present in the latter; and on the other hand, the cementation of Cu(2+) onto metallic iron contained in the mill scale. Rolling mill scale is seen to be an effective material for the removal of copper ions from aqueous solutions.

Process for recovering pertechnetate ions from an aqueous solution also containing other ions

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1997-02-18

A solid/liquid process for the separation and recovery of TcO{sub 4}{sup {minus}1} ions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups; whereas the aqueous solution from which the TcO{sub 4}{sup {minus}1} ions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt. A solid/liquid phase admixture of separation particles containing bound TcO{sub 4}{sup {minus}1} ions in such an aqueous solution that is free from MoO{sub 4}{sup {minus}2} ions is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture. 15 figs.

Molecular imprinted opal closest-packing photonic crystals for the detection of trace 17β-estradiol in aqueous solution.

PubMed

Sai, Na; Wu, Yuntang; Sun, Zhong; Huang, Guowei; Gao, Zhixian

2015-11-01

A novel opal closest-packing (OCP) photonic crystal (PC) was prepared by the introduction of molecular imprinting technique into the OCP PC. This molecular imprinted (MI)-OCP PC was fabricated via a vertical convective self-assembly method using 17β-estradiol (E2) as template molecules for monitoring E2 in aqueous solution. Morphology characterization showed that the MI-OCP PC possessed a highly ordered three-dimensional (3D) periodically-ordered structure, showing the desired structural color. The proposed PC material displayed a reduced reflection intensity when detecting E2 in water environment, because the molecular imprinting recognition events make the optical characteristics of PC change. The Bragg diffraction intensity decreased by 19.864 a.u. with the increase of E2 concentration from 1.5 ng mL(-1) to 364.5 ng mL(-1) within 6 min, whereas there were no obvious peak intensity changes for estriol, estrone, cholesterol, testosterone and diethylstilbestrol, indicating that the MI-OCP PC had selective and rapid response for E2 molecules. The adsorption results showed that the OCP structure and homogeneous layers were created in the MI-OCP PC with higher adsorption capacity. Thus, it was learned the MI-OCP PC is a simple prepared, sensitive, selective, and easy operative material, which shows promising use in routine supervision for residue detection in food and environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Gelation Kinetics and Network Structure of Cellulose Nanocrystals in Aqueous Solution.

PubMed

Peddireddy, Karthik R; Capron, Isabelle; Nicolai, Taco; Benyahia, Lazhar

2016-10-10

Cellulose nanocrystals (CNC) are rod-like biosourced nanoparticles that are widely used in a range of applications. Charged CNC was obtained by acid extraction from cotton and dispersed in aqueous solution using ultrasound and characterized by light scattering. Aggregation and gelation of CNC induced by addition of NaCl was investigated by light scattering as a function of the NaCl concentration (30-70 mM), the CNC concentration (0.5-5 g/L), and the temperature (10-60 °C). Formation of fractal aggregates was observed that grow with time until they percolate and form a weak system spanning network. The aggregation rate and gel time were found to decrease very steeply with increasing NaCl concentration and more weakly with increasing CNC concentration. A decrease of the gel time was also observed with increasing temperature for T > 20 °C. The structure of the CNC networks was studied using confocal laser scanning microscopy and light scattering. The local structure of the networks was fractal and reflected that of the constituting aggregates. The gels were homogeneous on length scales larger than the correlation length, which decreased with increasing CNC concentration. The CNC gels flowed when tilted for C < 12 g/L and sedimentation was observed macroscopically for C < 4 g/L due to the collapse of the CNC network under gravity. The speed and extent of sedimentation was investigated as a function of the ionic strength and the CNC concentration. Gelled CNC could be completely redispersed by applying ultrasound.

Water-Soluble Conjugated Polymers: Self-Assembly and Biosensor Applications

NASA Astrophysics Data System (ADS)

Bazan, Guillermo

2005-03-01

Homogeneous assays can be designed which take advantage of the optical amplification of conjugated polymers and the self-assembly characteristic of aqueous polyelectrolytes. For example, a ssDNA sequence sensor comprises an aqueous solution containing a cationic water soluble conjugated polymer such as poly(9,9-bis(trimethylammonium)-hexyl)-fluorene phenylene) with a peptide nucleic acid (PNA) labeled with a dye (PNA-C*). Signal transduction is controlled by hybridization of the neutral PNA-C* probe and the negative ssDNA target, resulting in favorable electrostatic interactions between the hybrid complex and the cationic polymer. Distance requirements for Förster energy transfer are thus met only when ssDNA of complementary sequence to the PNA-C* probe is present. Signal amplification by the conjugated polymer provides fluorescein emission >25 times higher than that of the directly excited dye. Transduction by electrostatic interactions followed by energy transfer is a general strategy. Examples involving other biomolecular recognition events, such as DNA/DNA, RNA/protein and RNA/RNA, will also be provided. The mechanism of biosensing will be discussed, with special attention to the varying contributions of hydrophobic and electrostatic forces, polymer conformation, charge density, local concentration of C*s and tailored defect sites for aggregation-induced optical changes. Finally, the water solubility of these conjugated polymers opens possibilities for spin casting onto organic materials, without dissolving the underlying layers. This property is useful for fabricating multilayer organic optoelectronic devices by simple solution techniques.

Ozonation of activated carbons: Effect on the adsorption of selected phenolic compounds from aqueous solutions.

PubMed

Alvarez, P M; García-Araya, J F; Beltrán, F J; Masa, F J; Medina, F

2005-03-15

The impact of ozonation on textural and chemical surface characteristics of two granular activated carbons (GAC), namely F400 and AQ40, and their ability to adsorb phenol (P), p-nitrophenol (PNP), and p-chlorophenol (PCP) from aqueous solutions have been studied. The porous structure of the ozone-treated carbons remained practically unchanged with regard to the virgin GAC. However, important modifications of the chemical surface and hydrophobicity were observed from FTIR spectroscopy, pH titrations, and determination of pH(PZC). As a rule, the ozone treatment at either room temperature (i.e., about 25 degrees C) or 100 degrees C gave rise to acidic surface oxygen groups (SOG). At 25 degrees C primarily carboxylic acids were formed while a more homogeneous distribution of carboxylic, lactonic, hydroxyl, and carbonyl groups was obtained at 100 degrees C. The experimental isotherms for phenolic compounds on both GAC were analyzed using the Langmuir model. Dispersive interactions between pi electrons of the ring of the aromatics and those of the carbon basal planes were thought to be the primary forces responsible for the physical adsorption whereas oxidative coupling of phenolic compounds catalyzed by basic SOG was a major cause of irreversible adsorption. The exposure of both GAC to ozone at room temperature decreased their ability to adsorb P, PNP, and PCP. However, when ozone was applied at 100 degrees C adsorption was not prevented but in some cases (P and PNP on F400) the adsorption process was even enhanced.

A Class of Homogeneous Scalar Tensor Cosmologies with a Radiation Fluid

NASA Astrophysics Data System (ADS)

Yazadjiev, Stoytcho S.

We present a new class of exact homogeneous cosmological solutions with a radiation fluid for all scalar tensor theories. The solutions belong to Bianchi type VIh cosmologies. Explicit examples of nonsingular homogeneous scalar tensor cosmologies are also given.

Homogeneous anisotropic solutions of topologically massive gravity with a cosmological constant and their homogeneous deformations

NASA Astrophysics Data System (ADS)

Moutsopoulos, George

2013-06-01

We solve the equations of topologically massive gravity (TMG) with a potentially non-vanishing cosmological constant for homogeneous metrics without isotropy. We only reproduce known solutions. We also discuss their homogeneous deformations, possibly with isotropy. We show that de Sitter space and hyperbolic space cannot be infinitesimally homogeneously deformed in TMG. We clarify some of their Segre-Petrov types and discuss the warped de Sitter spacetime.

Enthalpic parameters of interaction between diglycylglycine and polyatomic alcohols in aqueous solutions

NASA Astrophysics Data System (ADS)

Mezhevoi, I. N.; Badelin, V. G.

2015-12-01

Integral enthalpies of solution Δsol H m of diglycylglycine in aqueous solutions of glycerol, ethylene glycol, and 1,2-propylene glycol are measured via solution calorimetry. The experimental data are used to calculate the standard enthalpies of solution (Δsol H°) and transfer (Δtr H°) of the tripeptide from water to aqueous solutions of polyatomic alcohols. The enthalpic pairwise coefficients h xy of interactions between the tripeptide and polyatomic alcohol molecules are calculated using the McMillan-Mayer solution theory and are found to have positive values. The findings are discussed using the theory of estimating various types of interactions in ternary systems and the effect the structural features of interacting biomolecules have on the thermochemical parameters of diglycylglycine dissolution.

PROCESS FOR SEPARATING PLUTONIUM BY REPEATED PRECIPITATION WITH AMPHOTERIC HYDROXIDE CARRIERS

DOEpatents

Faris, B.F.

1960-04-01

A multiple carrier precipitation method is described for separating and recovering plutonium from an aqueous solution. The hydroxide of an amphoteric metal is precipitated in an aqueous plutonium-containing solution. This precipitate, which carries plutonium, is then separated from the supernatant liquid and dissolved in an aqueous hydroxide solution, forming a second plutonium- containing solution. lons of an amphoteric metal which forms an insoluble hydroxide under the conditions existing in this second solution are added to the second solution. The precipitate which forms and which carries plutonium is separated from the supernatant liquid. Amphoteric metals which may be employed are aluminum, bibmuth, copper, cobalt, iron, lanthanum, nickel, and zirconium.

Mechanistic roles of soil humus and minerals in the sorption of nonionic organic compounds from aqueous and organic solutions

USGS Publications Warehouse

Chiou, C.T.; Shoup, T.D.; Porter, P.E.

1985-01-01

Mechanistic roles of soil humus and soil minerals and their contributions to soil sorption of nonionic organic compounds from aqueous and organic solutions are illustrated. Parathion and lindane are used as model solutes on two soils that differ greatly in their humic and mineral contents. In aqueous systems, observed sorptive characteristics suggest that solute partitioning into the soil-humic phase is the primary mechanism of soil uptake. By contrast, data obtained from organic solutions on dehydrated soil partitioning into humic phase and adsorption by soil minerals is influenced by the soil-moisture content and by the solvent medium from which the solute is sorbed. ?? 1985.

A Novel Thermal Electrochemical Synthesis Method for Production of Stable Colloids of "Naked" Metal (Ag) Nanocrystals

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

Hu, Michael Z.; Easterly, Clay E

Solution synthesis of nanocrystal silver is reviewed. This paper reports a novel thermal electrochemical synthesis (TECS) for producing metal Ag nanocrystals as small as a few nanometers. The TECS method requires mild conditions (25-100oC), low voltage (1-50 V DC) on Ag electrodes, and simple water or aqueous solutions as reaction medium. Furthermore, a tubular dialysis membrane surround electrodes proves favorable to produce nanosized (<10 nm) Ag nanocrystals. Different from those nanocrystals reported in literature, our nanocrystals have several unique features: (1) small nanometer size, (2) nakedness , i.e., surfaces of metal nanocrystals are free of organic ligands or capping moleculesmore » and no need of dispersant in synthesis solutions, and (3) colloidally stable in water solutions. It was discovered that Ag nanoparticles with initially large size distribution can be homogenized into near-monodispersed system by a low power (< 15 mW) He-Ne laser exposure treatment. The combination of the TECS technique and the laser treatment could lead to a new technology that produces metal nanoparticles that are naked, stable, and uniform sized. In the presence of stabilizing agent (also as supporting electrolyte) such as polyvinyl alcohol (PVA), large yield of silver nanoparticles (<100nm) in the form of thick milky sols are produced.« less

How Does a Hydrophobic Macromolecule Respond to Mixed Osmolyte Environment?

PubMed

Tah, Indrajit; Mondal, Jagannath

2016-10-04

The role of the protecting osmolyte Trimethyl N-oxide (TMAO) in counteracting the denaturing effect of urea on a protein is quite well established. However, the mechanistic role of osmolytes on the hydrophobic interaction underlying protein folding is a topic of contention and is emerging as a key area of biophysical interest. Although recent experiment and computer simulation have established that individual aqueous solution of TMAO and urea respectively stabilizes and destabilizes the collapsed conformation of a hydrophobic polymer, it remains to be explored how a mixed aqueous solution of protecting and denaturing osmolytes influences the conformations of the polymer. In order to bridge the gap, we have simulated the conformational behavior of both a model hydrophobic polymer and a synthetic polymer polystyrene in an aqueous mixture of TMAO and urea. Intriguingly, our free energy based simulations on both the systems show that even though a pure aqueous solution of TMAO stabilizes the collapsed or globular conformation of the hydrophobic polymer, addition of TMAO to an aqueous solution of urea further destabilizes the collapsed conformation of the hydrophobic polymer. We also observe that the extent of destabilization in a mixed osmolyte solution is relatively higher than that in pure aqueous urea solution. The reinforcement of the denaturation effect of the hydrophobic macromolecule in a mixed osmolyte solution is in stark contrast to the well-known counteracting role of TMAO in proteins under denaturing condition of urea. In both model and realistic systems, our results show that in a mixed aqueous solution, greater number of cosolutes preferentially bind to the extended conformation of the polymer relative to that in the collapsed conformation, thereby complying with Tanford-Wyman preferential solvation theory disfavoring the collapsed conformation. The results are robust across a range of osmolyte concentrations and multiple cosolute forcefields. Our findings unequivocally imply that the action of mixed osmolyte solution on hydrophobic polymer is significantly distinct from that of proteins.

Iodinated natural rubber latex: preparation, characterisation & antibacterial activity assessment.

PubMed

Tyagi, M; Singh, S; Singh, H

2000-11-01

Natural Rubber (NR) in both its latex and dried form was treated with iodine to make it antibacterial in nature. The NR latex was dried and washed, dissolved in toluene, iodinated and cast into films. In a different approach, NR in its latex form (emulsion) was blended with aqueous solution of povidone-iodine complex (PVP-I) and films were cast. Phase separation of PVP-I was observed in the films prepared using NR latex; whereas the film prepared using NR solution in toluene and molecular iodine were homogeneous, transparent light brown. Solubility assessment of the films revealed that unlike pure NR, the iodinated NR failed to go into solution completely. The films obtained from both the approaches were evaluated for release of iodide ions. On immersion in water, PVP-I blended latex did not retain iodine while sustained release of iodide ion was observed in case of dried NR dissolved in toluene and treated with iodine. The FT-IR spectra of the iodinated films revealed that iodine attaches covalently to the double bonds in the isoprene units of NR. The films were also evaluated for their antibacterial properties and it was observed that the films prepared from both the approaches, acquired antimicrobial properties.

Homogenization Theory for the Prediction of Obstructed Solute Diffusivity in Macromolecular Solutions.

PubMed

Donovan, Preston; Chehreghanianzabi, Yasaman; Rathinam, Muruhan; Zustiak, Silviya Petrova

2016-01-01

The study of diffusion in macromolecular solutions is important in many biomedical applications such as separations, drug delivery, and cell encapsulation, and key for many biological processes such as protein assembly and interstitial transport. Not surprisingly, multiple models for the a-priori prediction of diffusion in macromolecular environments have been proposed. However, most models include parameters that are not readily measurable, are specific to the polymer-solute-solvent system, or are fitted and do not have a physical meaning. Here, for the first time, we develop a homogenization theory framework for the prediction of effective solute diffusivity in macromolecular environments based on physical parameters that are easily measurable and not specific to the macromolecule-solute-solvent system. Homogenization theory is useful for situations where knowledge of fine-scale parameters is used to predict bulk system behavior. As a first approximation, we focus on a model where the solute is subjected to obstructed diffusion via stationary spherical obstacles. We find that the homogenization theory results agree well with computationally more expensive Monte Carlo simulations. Moreover, the homogenization theory agrees with effective diffusivities of a solute in dilute and semi-dilute polymer solutions measured using fluorescence correlation spectroscopy. Lastly, we provide a mathematical formula for the effective diffusivity in terms of a non-dimensional and easily measurable geometric system parameter.

Simple introduction of carboxyl head group with alkyl spacer onto multiwalled carbon nanotubes by solution plasma process

NASA Astrophysics Data System (ADS)

Nemoto, Shimpei; Ueno, Tomonaga; Watthanaphanit, Anyarat; Hieda, Junko; Bratescu, Maria Antoaneta; Saito, Nagahiro

2017-09-01

A simple method of fabricating carboxyl-terminated multiwalled carbon nanotubes (MWCNTs) with alkyl spacers was developed to improve the dispersion quality of MWCNTs in aqueous solutions using solution plasma (SP) in a 6-aminocaproic acid solution. The formation of SP in the solution led to better dispersion of MWCNTs in aqueous solutions. Fourier transform infrared spectroscopy (FT-IR) results indicate that a carboxyl group with an alkyl spacer can be introduced by SP treatment in the 6-aminocaproic acid solution. Sedimentation tests show that the SP-treated MWCNTs in the 6-aminocaproic acid solution retained their good dispersion quality in aqueous solutions of pHs 5, 6, and 9. The alkyl spacer plays an important role in the preservation of dispersion states particularly at pH 6.

Aqueous penetration and biological activity of moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% solution in cataract surgery patients.

PubMed

Kim, Dianne H; Stark, Walter J; O'Brien, Terrence P; Dick, James D

2005-11-01

To measure the achievable perioperative aqueous concentration of the commercially available topically administered fourth generation fluoroquinolones, moxifloxacin 0.5% ophthalmic solution, and gatifloxacin 0.3% ophthalmic solution, and to correlate this concentration with the agents' biological efficacy in the aqueous humor of patients undergoing routine cataract surgery. Prospective, randomized, parallel, double-masked, clinical trial. Fifty patients undergoing cataract extraction. Patients (n = 25) were given perioperative topical moxifloxacin 0.5% or topical gatifloxacin 0.3% (n = 25). One drop of antibiotic was administered every 10 minutes for 4 doses beginning 1 hour prior to surgery. Aqueous humor was sampled via paracentesis and antibiotic concentrations were determined using validated high performance liquid chromatography (HPLC) procedures. Dilution analyses were performed to determine the biological efficacy of the agents in the aqueous against Staphylococcus epidermidis, the most common cause of postcataract endophthalmitis. Aqueous humor antibiotic concentrations were measured using HPLC and microdilution bioassay techniques. Biological activity was measured as minimal inhibitory dilution and minimal bactericidal dilution. Aqueous humor concentrations for moxifloxacin via HPLC analysis were 1.80 (+/-1.21) microg/ml, whereas those for gatifloxacin were 0.48 (+/-0.34) microg/ml. This 3.8-fold difference in aqueous humor antibiotic concentrations was statistically significant (P = 0.00003). Similarly, the biological dilution analysis of the aqueous humor samples showed that moxifloxacin attained an estimated activity of 2.1 microg/ml, whereas the gatifloxacin activity was approximately 0.4 mug/ml, which represented a 4.9-fold difference. This study demonstrated that after topically administered perioperative antibiotics with cataract surgery, moxifloxacin 0.5% ophthalmic solution achieved a statistically significantly higher concentration in aqueous humor compared with gatifloxacin (P = 0.00003). Results from the broth dilution analysis showed that moxifloxacin 0.5% was biologically more active against S. epidermidis than gatifloxacin 0.3% in aqueous humor after topical application. There were no adverse events reported, and incision wounds healed quickly and as expected.

Electromarking solution

DOEpatents

Bullock, Jonathan S.; Harper, William L.; Peck, Charles G.

1976-06-22

This invention is directed to an aqueous halogen-free electromarking solution which possesses the capacity for marking a broad spectrum of metals and alloys selected from different classes. The aqueous solution comprises basically the nitrate salt of an amphoteric metal, a chelating agent, and a corrosion-inhibiting agent.

SEPARATION OF TECHNETIUM FROM AQUEOUS SOLUTIONS BY COPRECIPITATION WITH MAGNETITE

DOEpatents

Rimshaw, S.J.

1961-10-24

A method of separating technetium in the 4+ oxidation state from an aqueous basic solution containing products of uranium fission is described. The method consists of contacting the solution with finely divided magnetite and recovering a technetium-bearing precipitate. (AEC)

Ice growth from supercooled aqueous solutions of benzene, naphthalene, and phenanthrene.

PubMed

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-08-23

Classical molecular dynamics (MD) were performed to investigate the growth of ice from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene. The main objective of this study is to explore the fate of those aromatic molecules after freezing of the supercooled aqueous solutions, i.e., if these molecules become trapped inside the ice lattice or if they are displaced to the QLL or to the interface with air. Ice growth from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene result in the formation of quasi-liquid layers (QLLs) at the air/ice interface that are thicker than those observed when pure supercooled water freezes. Naphthalene and phenanthrene molecules in the supercooled aqueous solutions are displaced to the air/ice interface during the freezing process at both 270 and 260 K; no incorporation of these aromatics into the ice lattice is observed throughout the freezing process. Similar trends were observed during freezing of supercooled aqueous solutions of benzene at 270 K. In contrast, a fraction of the benzene molecules become trapped inside the ice lattice during the freezing process at 260 K, with the rest of the benzene molecules being displaced to the air/ice interface. These results suggest that the size of the aromatic molecule in the supercooled aqueous solution is an important parameter in determining whether these molecules become trapped inside the ice crystals. Finally, we also report potential of mean force (PMF) calculations aimed at studying the adsorption of gas-phase benzene and phenanthrene on atmospheric air/ice interfaces. Our PMF calculations indicate the presence of deep free energy minima for both benzene and phenanthrene at the air/ice interface, with these molecules adopting a flat orientation at the air/ice interface.

Polymer-assisted aqueous deposition of metal oxide films

DOEpatents

Li, DeQuan [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

2003-07-08

An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

Recovering oil by injecting aqueous alkali, cosurfactant and gas

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

Reisberg, J.; Bielmowicz, L. J.; Thigpen, D. R.

1985-01-15

A process of recovering oil from a subterranean reservoir in which the oil is acidic but forms monovalent cation soaps of only relatively low interfacial activity when reacted with aqueous alkaline solutions, comprises displacing the oil toward a production location with a mixture of gas and cosurfactant-containing aqueous alkaline solution.

Membrane Treatment of Aqueous Film Forming Foam (AFFF) Wastes for Recovery of Its Active Ingredients

DTIC Science & Technology

1980-10-01

T ME1MBRANE TREATMENT OF AQUEOUS FILM FORMING FOAM~ (AFFF) WASTES FOR RECOVERY OFI Fts ACTIVE INGREDIENTS FINAL REPORT October 1980 by Edward S. K...OF THIS PAGEOPMn Date AVntr* d)__ ---- Ultrafiltration (UF) and Reverse Osmosis (RO) treatment of Aqueous Film Forming Foam (AFFF) solutions was...of Aqueous Film Forming Foam (AFFF) solutions was investigated to determine the feasibility of employing membrane processes to separate and recover

CO2 as a hydrogen vector - transition metal diamine catalysts for selective HCOOH dehydrogenation.

PubMed

Fink, Cornel; Laurenczy, Gábor

2017-01-31

The homogeneous catalytic dehydrogenation of formic acid in aqueous solution provides an efficient in situ method for hydrogen production, under mild conditions, and at an adjustable rate. We synthesized a series of catalysts with the chemical formula [(Cp*)M(N-N')Cl] (M = Ir, Rh; Cp* = pentamethylcyclopentadienyl; N-N = bidentate chelating nitrogen donor ligands), which have been proven to be active in selective formic acid decomposition in aqueous media. The scope of the study was to examine the relationship between stability and activity of catalysts for formic acid dehydrogenation versus electronic and steric properties of selected ligands, following a bottom-up approach by increasing the complexity of the N,N'-ligands progressively. The highest turnover frequency, TOF = 3300 h -1 was observed with a Cp*Ir(iii) complex bearing 1,2-diaminocyclohexane as the N,N'-donor ligand. From the variable temperature studies, the activation energy of formic acid dehydrogenation has been determined, E a = 77.94 ± 3.2 kJ mol -1 . It was observed that the different steric and electronic properties of the bidentate nitrogen donor ligands alter the catalytic activity and stability of the Ir and Rh compounds profoundly.

Cloud processing of organic compounds: Secondary organic aerosol and nitrosamine formation

NASA Astrophysics Data System (ADS)

Hutchings, James W., III

Cloud processing of atmospheric organic compounds has been investigated through field studies, laboratory experiments, and numerical modeling. Observational cloud chemistry studies were performed in northern Arizona and fog studies in central Pennsylvania. At both locations, the cloud and fogs showed low acidity due to neutralization by soil dust components (Arizona) and ammonia (Pennsylvania). The field observations showed substantial concentrations (20-5500 ng•L -1) of volatile organic compounds (VOC) in the cloud droplets. The potential generation of secondary organic aerosol mass through the processing of these anthropogenic VOCs was investigated through laboratory and modeling studies. Under simulated atmospheric conditions, in idealized solutions, benzene, toluene, ethylbenzene, and xylene (BTEX) degraded quickly in the aqueous phase with half lives of approximately three hours. The degradation process yielded less volatile products which would contribute to new aerosol mass upon cloud evaporation. However, when realistic cloud solutions containing natural organic matter were used in the experiments, the reaction kinetics decreased with increasing organic carbon content, resulting in half lives of approximately 7 hours. The secondary organic aerosol (SUA) mass formation potential of cloud processing of BTEX was evaluated. SOA mass formation by cloud processing of BTEX, while strongly dependent on the atmospheric conditions, could contribute up to 9% of the ambient atmospheric aerosol mass, although typically ˜1% appears realistic. Field observations also showed the occurrence of N-nitrosodimethylamine (NDMA), a potent carcinogen, in fogs and clouds (100-340 ng•L -1). Laboratory studies were conducted to investigate the formation of NDMA from nitrous acid and dimethylamine in the homogeneous aqueous phase within cloud droplets. While NDMA was produced in the cloud droplets, the low yields (<1%) observed could not explain observational concentrations. Therefore heterogeneous or gaseous formation of NDMA with partitioning to droplet must be the source of aqueous NDMA. Box-model calculations tended to demonstrate a predominance of a gas phase formation mechanism followed by partitioning into the cloud droplets. The calculations were consistent with field measurements of gaseous and aqueous NDMA concentrations. Measurements and model calculations showed that while NDMA is eventually photolyzed, it might persist in the atmosphere for hours.

Formation of silk fibroin nanoparticles in water-miscible organic solvent and their characterization

NASA Astrophysics Data System (ADS)

Zhang, Yu-Qing; Shen, Wei-De; Xiang, Ru-Li; Zhuge, Lan-Jian; Gao, Wei-Jian; Wang, Wen-Bao

2007-10-01

When Silk fibre derived from Bombyx mori, a native biopolymer, was dissolved in highly concentrated neutral salts such as CaCl2, the regenerated liquid silk, a gradually degraded peptide mixture of silk fibroin, could be obtained. The silk fibroin nanoparticles were prepared rapidly from the liquid silk by using water-miscible protonic and polar aprotonic organic solvents. The nanoparticles are insoluble but well dispersed and stable in aqueous solution and are globular particles with a range of 35-125 nm in diameter by means of TEM, SEM, AFM and laser sizer. Over one half of the ɛ-amino groups exist around the protein nanoparticles by using a trinitrobenzenesulfonic acid (TNBS) method. Raman spectra shows the tyrosine residues on the surface of the globules are more exposed than those on native silk fibers. The crystalline polymorph and conformation transition of the silk nanoparticles from random-coil and α-helix form (Silk I) into anti-parallel β-sheet form (Silk II) are investigated in detail by using infrared, fluorescence and Raman spectroscopy, DSC, 13C CP-MAS NMR and electron diffraction. X-ray diffraction of the silk nanoparticles shows that the nanoparticles crystallinity is about four fifths of the native fiber. Our results indicate that the degraded peptide chains of the regenerated silk is gathered homogeneously or heterogeneously to form a looser globular structure in aqueous solution. When introduced into excessive organic solvent, the looser globules of the liquid silk are rapidly dispersed and simultaneously dehydrated internally and externally, resulting in the further chain-chain contact, arrangement of those hydrophobic domains inside the globules and final formation of crystalline silk nanoparticles with β-sheet configuration. The morphology and size of the nanoparticles are relative to the kinds, properties and even molecular structures of organic solvents, and more significantly to the looser globular substructure of the degraded silk fibroin in aqueous solution. It is possible that the silk protein nanoparticles are potentially useful in biomaterials such as cosmetics, anti-UV skincare products, industrial materials and surface improving materials, especially in enzyme/drug delivery system as vehicle.

Reply to the comment by Wu et al. (2016) on "Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re-Os geochronometer to petroleum" [Geochim. Cosmochim. Acta 158 (2015) 1-21

NASA Astrophysics Data System (ADS)

Reisberg, Laurie; Michels, Raymond; Mahdaoui, Fatima

2016-08-01

We reply here to the questions raised by Wu et al. concerning the results published by Mahdaoui et al. (2015). This paper describes experiments in which aqueous solutions containing ReO4- and OsCl62- were brought in contact with natural oils at various ranges of concentration, time and temperature. The main observation is that the transfer of Re and Os to oils is very efficient under all experimental conditions. Wu et al. argue that thermodynamic equilibrium was not achieved in these experiments as apparent partition coefficients are inconsistent. They conclude that the experiments were flawed by possible leaking of reactors and that the conclusions by Mahdaoui et al. (2015) were not justified. In the following reply we explain that Mahdaoui et al. (2015) never claimed that thermodynamic equilibrium was achieved. Any calculations or considerations in this context are therefore meaningless. We recall the objectives of our publication, which were to experimentally test the behavior of ReO4- and OsCl6- (two plausible chemical forms of Re and Os in deep aquifers of petroleum systems) in aqueous solution-oil systems. To our knowledge these are the first experiments of their kind. The parameters that could influence the precision and reproducibility of our results were discussed in detail in Mahdaoui et al. (2015). The essential point is that all 60 of the experiments provide evidence of substantial transfer of Re and Os from water to oil. In contrast to what was mistakenly understood by Wu et al., the paper does not challenge the use of Re-Os to date geological events affecting petroleum. Instead, by providing a mechanism that might allow Os isotopic homogenization on a basin-wide scale, a critical step missing from most current models, it offers a possible explanation of how Re-Os geochronology in oils could potentially work. More generally, our study suggests that transfer of Re and Os from waters to oil may be an important phenomenon that should not be overlooked.

CH4 Hydrate Formation between Silica and Graphite Surfaces: Insights from Microsecond Molecular Dynamics Simulations.

PubMed

He, Zhongjin; Linga, Praveen; Jiang, Jianwen

2017-10-31

Microsecond simulations have been performed to investigate CH 4 hydrate formation from gas/water two-phase systems between silica and graphite surfaces, respectively. The hydrophilic silica and hydrophobic graphite surfaces exhibit substantially different effects on CH 4 hydrate formation. The graphite surface adsorbs CH 4 molecules to form a nanobubble with a flat or negative curvature, resulting in a low aqueous CH 4 concentration, and hydrate nucleation does not occur during 2.5 μs simulation. Moreover, an ordered interfacial water bilayer forms between the nanobubble and graphite surface thus preventing their direct contact. In contrast, the hydroxylated-silica surface prefers to be hydrated by water, with a cylindrical nanobubble formed in the solution, leading to a high aqueous CH 4 concentration and hydrate nucleation in the bulk region; during hydrate growth, the nanobubble is gradually covered by hydrate solid and separated from the water phase, hence slowing growth. The silanol groups on the silica surface can form strong hydrogen bonds with water, and hydrate cages need to match the arrangements of silanols to form more hydrogen bonds. At the end of the simulation, the hydrate solid is separated from the silica surface by liquid water, with only several cages forming hydrogen bonds with the silica surface, mainly due to the low CH 4 aqueous concentrations near the surface. To further explore hydrate formation between graphite surfaces, CH 4 /water homogeneous solution systems are also simulated. CH 4 molecules in the solution are adsorbed onto graphite and hydrate nucleation occurs in the bulk region. During hydrate growth, the adsorbed CH 4 molecules are gradually converted into hydrate solid. It is found that the hydrate-like ordering of interfacial water induced by graphite promotes the contact between hydrate solid and graphite. We reveal that the ability of silanol groups on silica to form strong hydrogen bonds to stabilize incipient hydrate solid, as well as the ability of graphite to adsorb CH 4 molecules and induce hydrate-like ordering of the interfacial water, are the key factors to affect CH 4 hydrate formation between silica and graphite surfaces.

Method for producing oxygen from lunar materials

NASA Technical Reports Server (NTRS)

Sullivan, Thomas A. (Inventor)

1993-01-01

This invention is related to producing oxygen from lunar or Martian materials, particularly from lunar ilmenite in situ. The process includes producing a slurry of the minerals and hot sulfuric acid, the acid and minerals reacting to form sulfates of the metal. Water is added to the slurry to dissolve the minerals into an aqueous solution, the first aqueous solution is separated from unreacted minerals from the slurry, and the aqueous solution is electrolyzed to produce the metal and oxygen.

A fluorescent sensor for selective detection of cyanide using mesoporous graphitic carbon(IV) nitride.

PubMed

Lee, Eun Zoo; Lee, Sun Uk; Heo, Nam-Su; Stucky, Galen D; Jun, Young-Si; Hong, Won Hi

2012-04-25

A turn-on fluorescence sensor, Cu(2+)-c-mpg-C(3)N(4), was developed for detection of CN(-) in aqueous solution by simply mixing cubic mesoporous graphitic carbon nitride (c-mpg-C(3)N(4)) and aqueous solution of Cu(NO(3))(2). The highly sensitive detection of CN(-) with a detection limit of 80 nM is not only possible in aqueous solution but also in human blood serum.

Stiffness-independent highly efficient on-chip extraction of cell-laden hydrogel microcapsules from oil emulsion into aqueous solution by dielectrophoresis

PubMed Central

Huang, Haishui; Sun, Mingrui; Heisler-Taylor, Tyler; Kiourti, Asimina; Volakis, John; Lafyatis, Gregory

2015-01-01

A dielectrophoresis (DEP)-based method is reported to achieve highly efficient on-chip extraction of cell-laden microcapsules of any stiffness from oil into aqueous solution. The hydrogel microcapsules can be extracted into the aqueous solution by DEP and interfacial tension (IFT) forces with no trapped oil while the encapsulated cells are free from the electrical damages due to the Faraday cage effect. PMID:26297051

SALICYLATE PROCESS FOR THORIUM SEPARATION FROM RARE EARTHS

DOEpatents

Cowan, G.A.

1959-08-25

The separation of thorium from rare earths is accomplished by forming an aqueous solution of salts of thorium and rare earths and sufficient acetate buffer to provide a pH of between 2 and 5, adding an ammonium salicylate to the aqueous buffered solution, contacting the resultant solution with a substantially water-immiscible organic solvent mixture of an ether and an ester, and separating the solvent extract phase containing thorium salicylate from the aqueous phase containing the rare earths.

Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere. II. Classification of axisymmetric no-swirl solutions

NASA Astrophysics Data System (ADS)

Li, Li; Li, YanYan; Yan, Xukai

2018-05-01

We classify all (- 1)-homogeneous axisymmetric no-swirl solutions of incompressible stationary Navier-Stokes equations in three dimension which are smooth on the unit sphere minus the south and north poles, parameterizing them as a four dimensional surface with boundary in appropriate function spaces. Then we establish smoothness properties of the solution surface in the four parameters. The smoothness properties will be used in a subsequent paper where we study the existence of (- 1)-homogeneous axisymmetric solutions with non-zero swirl on S2 ∖ { S , N }, emanating from the four dimensional solution surface.

Adsorption of arsenic from aqueous solution using magnetic graphene oxide

NASA Astrophysics Data System (ADS)

Sherlala, A. I. A.; Raman, A. A.; Bello, M. M.

2017-06-01

A binary of graphene oxide (GO) and iron oxide (IO) was prepared and used for the removal of arsenic from aqueous solution. The synthesized compound was characterized using XRD analysis. The prepared composite was used for the adsorption of arsenic from aqueous solution. Central Composite Design was used to design the adsorption experiments and to investigate the effects of operational parameters (initial concentration of arsenic, adsorbent dosage, pH and time) on the adsorption capacity and efficiency. The adsorbent shows a high adsorption capacity for the arsenic. The adsorption efficiency ranges between 33.2 % and 99.95 %. The most significant factors affecting the adsorption capacity were found to be the initial concentration of arsenic and the adsorbent dosage. The initial pH of the solution slightly affects the adsorption capacity, with the maximum adsorption capacity occurring around pH 6 - 7. Thus, the developed adsorbent has a potential for effective removal of arsenic from aqueous solution.

Defining microchannels and valves on a hydrophobic paper by low-cost inkjet printing of aqueous or weak organic solutions.

PubMed

Cai, Longfei; Zhong, Minghua; Li, Huolin; Xu, Chunxiu; Yuan, Biyu

2015-07-01

We describe a simple and cost-effective strategy for rapid fabrication of microfluidic paper-based analytical devices and valves by inkjet printing. NaOH aqueous solution was printed onto a hydrophobic filter paper, which was previously obtained by soaking in a trimethoxyoctadecylsilane-heptane solution, allowing selective wet etching of hydrophobic cellulose to create hydrophilic-hydrophobic contrast with a relatively good resolution. Hexadecyltrimethylammonium bromide (CTMAB)-ethanol solution was printed onto hydrophobic paper to fabricate temperature-controlled valves. At low temperature, CTMAB deposited on the paper is insoluble in aqueous fluid, thus the paper remains hydrophobic. At high temperature, CTMAB becomes soluble so the CTMAB-deposited channel becomes hydrophilic, allowing the wicking of aqueous solution through the valve. We believe that this strategy will be very attractive for the development of simple micro analytical devices for point-of-care applications, including diagnostic testing, food safety control, and environmental monitoring.

Adsorptive removal of antibiotics from aqueous solution using carbon materials.

PubMed

Yu, Fei; Li, Yong; Han, Sheng; Ma, Jie

2016-06-01

Antibiotics, an important type of environmental contamination, have attracted many researchers to the study of their removal from aqueous solutions. Adsorption technology is a fast, efficient, and economical physicochemical method that is extensively used in wastewater treatment. From original activated carbon and carbon nanotubes to the latest graphene-based materials, carbon-based materials have been widely used as highly effective adsorbents for contaminant removal from aqueous solution because of their large specific surface area, high porosity, and high reaction activity. In this article, adsorption removal methods for four major types of antibiotic (tetracyclines, sulfonamides, macrolides, and quinolones) are reviewed. We also provide an overview of the application development of carbon materials as adsorbents for antibiotic removal from aqueous solution. The most promising works are discussed, and the main challenges in preparing high-performance adsorbents and the development tendency of adsorbents are also analyzed. This work provides theoretical guidance for subsequent research in the design and modification of carbon materials for applications in the adsorption removal of antibiotics from aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of chromium(III) from aqueous waste solution by liquid-liquid extraction in a circular microchannel.

PubMed

Luo, Jian Hong; Li, Jun; Guo, Lei; Zhu, Xin Hua; Dai, Shuang; Li, Xing

2017-11-01

A new circular microchannel device has been proposed for the removal of chromium(III) from aqueous waste solution by using kerosene as a diluent and (2-ethylhexyl) 2-ethylhexyl phosphonate as an extractant. The proposed device has several advantages such as a flexible and easily adaptable design, easy maintenance, and cheap setup without the requirement of microfabrication. To study the extraction efficiency and advantages of the circular microchannel device in the removal of chromium(III), the effects of various operating conditions such as the inner diameter of the channel, the total flow velocity, the phase ratio, the initial pH of aqueous waste solution, the reaction temperature and the initial concentration of extractant on the extraction efficiency are investigated and the optimal process conditions are obtained. The results show that chromium(III) in aqueous waste solution can be effectively removed with (2-ethylhexyl) 2-ethylhexyl phosphonate in the circular microchannel. Under optimized conditions, an extraction efficiency of chromium(III) of more than 99% can be attained and the aqueous waste solution can be discharged directly, which can meet the Chinese national emission standards.

Thermodynamic and structure-property study of liquid-vapor equilibrium for aroma compounds.

PubMed

Tromelin, Anne; Andriot, Isabelle; Kopjar, Mirela; Guichard, Elisabeth

2010-04-14

Thermodynamic parameters (T, DeltaH degrees , DeltaS degrees , K) were collected from the literature and/or calculated for five esters, four ketones, two aldehydes, and three alcohols, pure compounds and compounds in aqueous solution. Examination of correlations between these parameters and the range values of DeltaH degrees and DeltaS degrees puts forward the key roles of enthalpy for vaporization of pure compounds and of entropy in liquid-vapor equilibrium of compounds in aqueous solution. A structure-property relationship (SPR) study was performed using molecular descriptors on aroma compounds to better understand their vaporization behavior. In addition to the role of polarity for vapor-liquid equilibrium of compounds in aqueous solution, the structure-property study points out the role of chain length and branching, illustrated by the correlation between the connectivity index CHI-V-1 and the difference between T and log K for vaporization of pure compounds and compounds in aqueous solution. Moreover, examination of the esters' enthalpy values allowed a probable conformation adopted by ethyl octanoate in aqueous solution to be proposed.

Surface tensions of inorganic multicomponent aqueous electrolyte solutions and melts.

PubMed

Dutcher, Cari S; Wexler, Anthony S; Clegg, Simon L

2010-11-25

A semiempirical model is presented that predicts surface tensions (σ) of aqueous electrolyte solutions and their mixtures, for concentrations ranging from infinitely dilute solution to molten salt. The model requires, at most, only two temperature-dependent terms to represent surface tensions of either pure aqueous solutions, or aqueous or molten mixtures, over the entire composition range. A relationship was found for the coefficients of the equation σ = c(1) + c(2)T (where T (K) is temperature) for molten salts in terms of ion valency and radius, melting temperature, and salt molar volume. Hypothetical liquid surface tensions can thus be estimated for electrolytes for which there are no data, or which do not exist in molten form. Surface tensions of molten (single) salts, when extrapolated to normal temperatures, were found to be consistent with data for aqueous solutions. This allowed surface tensions of very concentrated, supersaturated, aqueous solutions to be estimated. The model has been applied to the following single electrolytes over the entire concentration range, using data for aqueous solutions over the temperature range 233-523 K, and extrapolated surface tensions of molten salts and pure liquid electrolytes: HCl, HNO(3), H(2)SO(4), NaCl, NaNO(3), Na(2)SO(4), NaHSO(4), Na(2)CO(3), NaHCO(3), NaOH, NH(4)Cl, NH(4)NO(3), (NH(4))(2)SO(4), NH(4)HCO(3), NH(4)OH, KCl, KNO(3), K(2)SO(4), K(2)CO(3), KHCO(3), KOH, CaCl(2), Ca(NO(3))(2), MgCl(2), Mg(NO(3))(2), and MgSO(4). The average absolute percentage error between calculated and experimental surface tensions is 0.80% (for 2389 data points). The model extrapolates smoothly to temperatures as low as 150 K. Also, the model successfully predicts surface tensions of ternary aqueous mixtures; the effect of salt-salt interactions in these calculations was explored.

Unravelling the pH-dependence of a molecular photocatalytic system for hydrogen production† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5sc01349f Click here for additional data file.

PubMed Central

Pastor, Ernest; Gross, Manuela A.; Selim, Shababa

2015-01-01

Photocatalytic systems for the reduction of aqueous protons are strongly pH-dependent, but the origin of this dependency is still not fully understood. We have studied the effect of different degrees of acidity on the electron transfer dynamics and catalysis taking place in a homogeneous photocatalytic system composed of a phosphonated ruthenium tris(bipyridine) dye (RuP) and a nickel bis(diphosphine) electrocatalyst (NiP) in an aqueous ascorbic acid solution. Our approach is based on transient absorption spectroscopy studies of the efficiency of photo-reduction of RuP and NiP correlated with pH-dependent photocatalytic H2 production and the degree of catalyst protonation. The influence of these factors results in an observed optimum photoactivity at pH 4.5 for the RuP–NiP system. The electron transfer from photo-reduced RuP to NiP is efficient and independent of the pH value of the medium. At pH <4.5, the efficiency of the system is limited by the yield of RuP photo-reduction by the sacrificial electron donor, ascorbic acid. At pH >4.5, the efficiency of the system is limited by the poor protonation of NiP, which inhibits its ability to reduce protons to hydrogen. We have therefore developed a rational strategy utilising transient absorption spectroscopy combined with bulk pH titration, electrocatalytic and photocatalytic experiments to disentangle the complex pH-dependent activity of the homogenous RuP–NiP photocatalytic system, which can be widely applied to other photocatalytic systems. PMID:28717491

REMOVAL OF CESIUM BY SORPTION FROM AQUEOUS SOLUTIONS

DOEpatents

Ames, L.L.

1962-01-16

ABS>A process is given for selectively removing cesium from acid aqueous solutions containing cesium in microquantities and other cations in macroquantities by absorption on clinoptilolite. The cesium can be eluted from the clinoptilolite with a solution of ammonia, potassium hydroxide, or rubidium hydroxide. (AEC)

EXTRACTION METHOD FOR SEPARATING URANIUM, PLUTONIUM, AND FISSION PRODUCTS FROM COMPOSITIONS CONTAINING SAME

DOEpatents

Seaborg, G.T.

1957-10-29

Methods for separating plutonium from the fission products present in masses of neutron irradiated uranium are reported. The neutron irradiated uranium is first dissolved in an aqueous solution of nitric acid. The plutonium in this solution is present as plutonous nitrate. The aqueous solution is then agitated with an organic solvent, which is not miscible with water, such as diethyl ether. The ether extracts 90% of the uraryl nitrate leaving, substantially all of the plutonium in the aqueous phase. The aqueous solution of plutonous nitrate is then oxidized to the hexavalent state, and agitated with diethyl ether again. In the ether phase there is then obtained 90% of plutonium as a solution of plutonyl nitrate. The ether solution of plutonyl nitrate is then agitated with water containing a reducing agent such as sulfur dioxide, and the plutonium dissolves in the water and is reduced to the plutonous state. The uranyl nitrate remains in the ether. The plutonous nitrate in the water may be recovered by precipitation.

The relative viscosity of NaNO 3 and NaNO 2 aqueous solutions

DOE PAGES

Reynolds, Jacob G.; Mauss, Billie M.; Daniel, Richard C.

2018-05-09

In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO 2 and NaNO 3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO 2 and NaNO 3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO 2 solutions was consistently larger than NaNO 3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms ofmore » quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. Furthermore, these hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.« less

The relative viscosity of NaNO 3 and NaNO 2 aqueous solutions

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

Reynolds, Jacob G.; Mauss, Billie M.; Daniel, Richard C.

In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO 2 and NaNO 3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO 2 and NaNO 3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO 2 solutions was consistently larger than NaNO 3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms ofmore » quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. Furthermore, these hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.« less

Recovery of alkali metal constituents from catalytic coal conversion residues

DOEpatents

Soung, Wen Y.

1984-01-01

In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them (46, 53, 61, 69) with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide (63) to precipitate silicon constituents, the pH of the resultant solution is increased (81), preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated (84) to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process (86, 18, 17) where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

Freeze-thawing behaviour of highly concentrated aqueous alkali chloride-glucose systems.

PubMed

Kajiwara, K; Motegi, A; Murase, N

2001-01-01

The freeze-thawing behaviour of highly concentrated aqueous alkali chloride-glucose systems was investigated by differential scanning calorimetry (DSC). In the aqueous NaCl-glucose solution system, single or double glass transitions followed by the corresponding devitrification exotherms were observed during rewarming. In the aqueous KCl-glucose solution system, on the other hand, a single glass transition followed by an exotherm was observed during rewarming. The presence of double glass transitions observed for a certain composition of the aqueous NaCl-glucose solution was taken as an evidence for the liquid-liquid immiscibility at low temperatures. Two kinds of crystallisation accompanied by exotherms during rewarming were identified by X-ray diffraction as ice and ice/NaCl x 2H(2)O, or ice/KCl eutectic component.

Supramolecular metal-organic frameworks that display high homogeneous and heterogeneous photocatalytic activity for H2 production

NASA Astrophysics Data System (ADS)

Tian, Jia; Xu, Zi-Yue; Zhang, Dan-Wei; Wang, Hui; Xie, Song-Hai; Xu, Da-Wen; Ren, Yuan-Hang; Wang, Hao; Liu, Yi; Li, Zhan-Ting

2016-05-01

Self-assembly has a unique presence when it comes to creating complicated, ordered supramolecular architectures from simple components under mild conditions. Here, we describe a self-assembly strategy for the generation of the first homogeneous supramolecular metal-organic framework (SMOF-1) in water at room temperature from a hexaarmed [Ru(bpy)3]2+-based precursor and cucurbit[8]uril (CB[8]). The solution-phase periodicity of this cubic transition metal-cored supramolecular organic framework (MSOF) is confirmed by small-angle X-ray scattering and diffraction experiments, which, as supported by TEM imaging, is commensurate with the periodicity in the solid state. We further demonstrate that SMOF-1 adsorbs anionic Wells-Dawson-type polyoxometalates (WD-POMs) in a one-cage-one-guest manner to give WD-POM@SMOF-1 hybrid assemblies. Upon visible-light (500 nm) irradiation, such hybrids enable fast multi-electron injection from photosensitive [Ru(bpy)3]2+ units to redox-active WD-POM units, leading to efficient hydrogen production in aqueous media and in organic media. The demonstrated strategy opens the door for the development of new classes of liquid-phase and solid-phase ordered porous materials.

Supramolecular metal-organic frameworks that display high homogeneous and heterogeneous photocatalytic activity for H 2 production

DOE PAGES

Tian, Jia; Xu, Zi-Yue; Zhang, Dan-Wei; ...

2016-05-10

Self-assembly has a unique presence when it comes to creating complicated, ordered supramolecular architectures from simple components under mild conditions. Here, we describe a self-assembly strategy for the generation of the first homogeneous supramolecular metal-organic framework (SMOF-1) in water at room temperature from a hexaarmed [Ru(bpy) 3 ] 2+ -based precursor and cucurbit[8] uril (CB[8]). The solution-phase periodicity of this cubic transition metal-cored supramolecular organic framework (MSOF) is confirmed by small-angle X-ray scattering and diffraction experiments, which, as supported by TEM imaging, is commensurate with the periodicity in the solid state. We further demonstrate that SMOF-1 adsorbs anionic Wells-'Dawson-type polyoxometalatesmore » (WD-POMs) in a one-cage-one-guest manner to give WD-POM@SMOF-1 hybrid assemblies. Upon visible-light (500 nm) irradiation, such hybrids enable fast multi-electron injection from photosensitive [Ru(bpy) 3 ] 2+ units to redox-active WD-POM units, leading to efficient hydrogen production in aqueous media and in organic media. The demonstrated strategy opens the door for the development of new classes of liquid-phase and solid-phase ordered porous materials.« less

Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited.

PubMed

Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G; Manohar, Srirang

2011-07-01

A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.

Exploring Solute-Solvent Interactions of -Amino Acids in Aqueous [] Arrangements by Volumetric, Viscometric, Refractometric, and Acoustic Approach

NASA Astrophysics Data System (ADS)

Roy, Mahendra Nath; Roy, Milan Chandra; Basak, Saptarshi

2014-05-01

Qualitative and quantitative analysis of molecular interaction prevailing in glycine, l-alanine, l-valine, and aqueous solution of ionic liquid (IL) [1-ethylpyridinium tetrafluoroborate (] have been investigated by thermophysical properties. The apparent molar volume (), viscosity -coefficient, molal refraction (), and adiabatic compressibility ( of glycine, l-alanine, and l-valine have been studied in 0.001 mol , 0.003 mol , and 0.005 mol aqueous 1-ethylpyridinium tetrafluoroborate [] solutions at 298.15 K from the values of densities , viscosities (), refractive index (, and speed of sound , respectively. The extent of interaction, i.e., the solute-solvent interaction is expressed in terms of the limiting apparent molar volume (, viscosity -coefficient, and limiting apparent molar adiabatic compressibility (. The limiting apparent molar volumes (, experimental slopes ( derived from the Masson equation, and viscosity - and -coefficients using the Jones-Dole equation have been interpreted in terms of ion-ion and ion-solvent interactions, respectively. Molal refractions ( have been calculated with the help of the Lorentz-Lorenz equation. The role of the solvent (aqueous IL solution) and the contribution of solute-solute and solute-solvent interactions to the solution complexes have also been analyzed through the derived properties.

Selected specific rates of reactions of transients from water in aqueous solution. Hydrated electron, supplemental data. [Reactions with transients from water, with inorganic solutes, and with solutes

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

Ross, A.B.

1975-06-01

A compilation of rates of reactions of hydrated electrons with other transients and with organic and inorganic solutes in aqueous solution appeared in NSRDS-NBS 43, and covered the literature up to early 1971. This supplement includes additional rates which have been published through July 1973.

Options for refractive index and viscosity matching to study variable density flows

NASA Astrophysics Data System (ADS)

Clément, Simon A.; Guillemain, Anaïs; McCleney, Amy B.; Bardet, Philippe M.

2018-02-01

Variable density flows are often studied by mixing two miscible aqueous solutions of different densities. To perform optical diagnostics in such environments, the refractive index of the fluids must be matched, which can be achieved by carefully choosing the two solutes and the concentration of the solutions. To separate the effects of buoyancy forces and viscosity variations, it is desirable to match the viscosity of the two solutions in addition to their refractive index. In this manuscript, several pairs of index matched fluids are compared in terms of viscosity matching, monetary cost, and practical use. Two fluid pairs are studied in detail, with two aqueous solutions (binary solutions of water and a salt or alcohol) mixed into a ternary solution. In each case: an aqueous solution of isopropanol mixed with an aqueous solution of sodium chloride (NaCl) and an aqueous solution of glycerol mixed with an aqueous solution of sodium sulfate (Na_2SO_4). The first fluid pair allows reaching high-density differences at low cost, but brings a large difference in dynamic viscosity. The second allows matching dynamic viscosity and refractive index simultaneously, at reasonable cost. For each of these four solutes, the density, kinematic viscosity, and refractive index are measured versus concentration and temperature, as well as wavelength for the refractive index. To investigate non-linear effects when two index-matched, binary solutions are mixed, the ternary solutions formed are also analyzed. Results show that density and refractive index follow a linear variation with concentration. However, the viscosity of the isopropanol and NaCl pair deviates from the linear law and has to be considered. Empirical correlations and their coefficients are given to create index-matched fluids at a chosen temperature and wavelength. Finally, the effectiveness of the refractive index matching is illustrated with particle image velocimetry measurements performed for a buoyant jet in a linearly stratified environment. The creation of the index-matched solutions and linear stratification in a large-scale experimental facility are detailed, as well as the practical challenges to obtain precise refractive index matching.

Method for loading resin beds

DOEpatents

Notz, Karl J.; Rainey, Robert H.; Greene, Charles W.; Shockley, William E.

1978-01-01

An improved method of preparing nuclear reactor fuel by carbonizing a uranium loaded cation exchange resin provided by contacting a H.sup.+ loaded resin with a uranyl nitrate solution deficient in nitrate, comprises providing the nitrate deficient solution by a method comprising the steps of reacting in a reaction zone maintained between about 145.degree.-200.degree. C, a first aqueous component comprising a uranyl nitrate solution having a boiling point of at least 145.degree. C with a second aqueous component to provide a gaseous phase containing HNO.sub.3 and a reaction product comprising an aqueous uranyl nitrate solution deficient in nitrate.

Solar Metal Sulfate-Ammonia Based Thermochemical Water Splitting Cycle for Hydrogen Production

NASA Technical Reports Server (NTRS)

T-Raissi, Ali (Inventor); Muradov, Nazim (Inventor); Huang, Cunping (Inventor)

2014-01-01

Two classes of hybrid/thermochemical water splitting processes for the production of hydrogen and oxygen have been proposed based on (1) metal sulfate-ammonia cycles (2) metal pyrosulfate-ammonia cycles. Methods and systems for a metal sulfate MSO.sub.4--NH3 cycle for producing H2 and O2 from a closed system including feeding an aqueous (NH3)(4)SO3 solution into a photoctalytic reactor to oxidize the aqueous (NH3)(4)SO3 into aqueous (NH3)(2)SO4 and reduce water to hydrogen, mixing the resulting aqueous (NH3)(2)SO4 with metal oxide (e.g. ZnO) to form a slurry, heating the slurry of aqueous (NH4)(2)SO4 and ZnO(s) in the low temperature reactor to produce a gaseous mixture of NH3 and H2O and solid ZnSO4(s), heating solid ZnSO4 at a high temperature reactor to produce a gaseous mixture of SO2 and O2 and solid product ZnO, mixing the gaseous mixture of SO2 and O2 with an NH3 and H2O stream in an absorber to form aqueous (NH4)(2)SO3 solution and separate O2 for aqueous solution, recycling the resultant solution back to the photoreactor and sending ZnO to mix with aqueous (NH4)(2)SO4 solution to close the water splitting cycle wherein gaseous H2 and O2 are the only products output from the closed ZnSO4--NH3 cycle.

SEPARATION OF HAFNIUM FROM ZIRCONIUM

DOEpatents

Overholser, L.B.; Barton, C.J. Sr.; Ramsey, J.W.

1960-05-31

The separation of hafnium impurities from zirconium can be accomplished by means of organic solvent extraction. The hafnium-containing zirconium feed material is dissolved in an aqueous chloride solution and the resulting solution is contacted with an organic hexone phase, with at least one of the phases containing thiocyanate. The hafnium is extracted into the organic phase while zirconium remains in the aqueous phase. Further recovery of zirconium is effected by stripping the onganic phase with a hydrochloric acid solution and commingling the resulting strip solution with the aqueous feed solution. Hexone is recovered and recycled by means of scrubbing the onganic phase with a sulfuric acid solution to remove the hafnium, and thiocyanate is recovered and recycled by means of neutralizing the effluent streams to obtain ammonium thiocyanate.

RECOVERY OF PROTACTINIUM

DOEpatents

Kraus, K.A.; Moore, G.E.

1959-02-01

A process is presented for the separation of protactinium values from an aqueous solution containing Pa and Th values comprising establishing in the solution a HCl concentration of from 4 to 11 molar, contacting the resulting solution with an anion-exchange adsorbent, such as a polystyrene divinyl benzene polymer with quatenary amines as the active exchange group, to effect the adsorption of Pa values upon the adsorbent while leaving Th values in the solution, and then washlng the separated Pa bearing adsorbent with an aqueous solution of HCl of less than 4M to exclusively elute Pa values from the adsorbent. If hexavalent U values are contained in the original solution thcy are adsorbed on the resin together with Pa. A separation is offected chromatographically by percolating the resin with aqueous HCl.

Cryosalt Formation in Delaminated Clays

NASA Astrophysics Data System (ADS)

Yeşilbaş, Merve; Boily, Jean-François

2017-04-01

Hydrohalite (NaClṡ2H2O) forms by evaporation, sublimation and freezing of aqueous solutions of NaCl. Although this process is traditionally deemed to occur in aqueous solutions little attention has been paid on whether this is possible with minerals. Smectite minerals are particularly interesting in this regard for their ability to accommodate water between aluminosilicate sheets, allowing them to swell and even delaminate. In particular, montmorillonite possesses high affinities for water and can play important roles in water retention and ice formation in nature, as well as in strategies for nuclear waste storage and even for technological applications. [1,2] For this study, we aimed to develop insight into the molecular-level nature of hydrohalite formation at surfaces of montmorillonite particles as well as in their interlayers. Thin films of Na+ and Ca2+ exchanged montmorillonites deposited on a diamond-based Attenuated Total Reflectance (ATR) cell were interacted with (0.01, 0.1, 1 and 5M) NaCl solutions, and then frozen to -10˚ C. The resulting frozen montmorillonites pastes were then probed by ATR Fourier Transform Infrared (FTIR) spectroscopy, which is a highly sensitive technique for probing hydrogen bonding in minerals and water. Our results on Na-montmorillonite showed that hydrohalite, with its characteristic O-H stretching (νOH ˜ 3245-3265, 3408, 3462, 3555 cm-1) and bending (δOH ˜ 1614 and 1641 cm-1) bands, formed from solutions of at least 0.1 M NaCl, yet well below the typical homogeneous crystallization of this phase from pure aqueous solutions.[3] Further analysis of the O-H stretching and silicate (νSi-O ˜1000 cm-1) regions of frozen paste of montmorillonites revealed that hydrohalite formed within interlayers and at surfaces of Na-montmorillonite. Ca-montmorillonite did not, on the other hand, promote hydrohalite formation but did undergo Ca2+/Na+ ion exchange due to exposure of the NaCl solutions. Given the inability of Ca-montmorillonite at hosting hydrohalite, the results of this study can be used to suggest that delaminated Na-montmorillonite sheets encapsulate the salt solutions and by preventing sublimation of water, promotes crystallization of hydrohalite. As delamination is not possible in Ca-montmorillonite, water more readily sublimated from the system, leaving behind a dry Ca-montmorillonite/NaCl assemblage. As such, this work identified processes through which clay minerals can affect the formation of cryosalts that are not only of importance to terrestrial environments of the cryosphere but also to atmospheric processes involving dust aerosols. [1] Yeşilbaş, M. and Boily, J.-F. (2016), Scientific Reports. 6, 32136. [2] Yeşilbaş, M. and Boily, J.-F. (2016), J. Phys. Chem. Lett. 7, 2849-2855. [3] Wagner, R., Möhler O., Schnaiter, M. (2012), 33, 8557-8571.

Singlet Oxygen in Aqueous Solution: A Lecture Demonstration

ERIC Educational Resources Information Center

Shakhashiri, Bassam Z.; Williams, Lloyd G.

1976-01-01

Describes a demonstration that illustrates the red chemiluminescence due to singlet molecular oxygen that can be observed when aqueous solutions of hypochlorite ion and hydrogen peroxide are mixed. (MLH)

Thermodynamic studies of aqueous and CCl4 solutions of 15-crown-5 at 298.15 K: an application of McMillan-Mayer and Kirkwood-Buff theories of solutions.

PubMed

Dagade, Dilip H; Shetake, Poonam K; Patil, Kesharsingh J

2007-07-05

The density and osmotic coefficient data for solutions of 15-crown-5 (15C5) in water and in CCl4 solvent systems at 298.15 K have been reported using techniques of densitometry and vapor pressure osmometry in the concentration range of 0.01-2 mol kg-1. The data are used to obtain apparent molar and partial molar volumes, activity coefficients of the components as a function of 15C5 concentration. Using the literature heat of dilution data for aqueous system, it has become possible to calculate entropy of mixing (DeltaS(mix)), excess entropy of solution (DeltaS(E)), and partial molar entropies of the components at different concentrations. The results of all these are compared to those obtained for aqueous 18-crown-6 solutions reported earlier. It has been observed that the partial molar volume of 15C5 goes through a minimum and that of water goes through a maximum at approximately 1.2 mol kg(-1) in aqueous solutions whereas the opposite is true in CCl4 medium but at approximately 0.5 mol kg(-1). The osmotic and activity coefficients of 15C5 and excess free energy change for solution exhibit distinct differences in the two solvent systems studied. These results have been explained in terms of hydrophobic hydration and interactions in aqueous solution while weak solvophobic association of 15C5 molecules in CCl4 solutions is proposed. The data are further subjected to analysis by applying McMillan-Mayer and Kirkwood-Buff theories of solutions. The analysis shows that osmotic second virial coefficient value for 15C5 is marginally less than that of 18C6 indicating that reduction in ring flexibility does not affect the energetics of the interactions much in aqueous solution while the same gets influenced much in nonpolar solvent CCl4.

Stiffness-Independent Highly Efficient On-Chip Extraction of Cell-Laden Hydrogel Microcapsules from Oil Emulsion into Aqueous Solution by Dielectrophoresis.

PubMed

Huang, Haishui; Sun, Mingrui; Heisler-Taylor, Tyler; Kiourti, Asimina; Volakis, John; Lafyatis, Gregory; He, Xiaoming

2015-10-28

A dielectrophoresis (DEP)-based method achieves highly efficient on-chip extraction of cell-laden microcapsules of any stiffness from oil into aqueous solution. The hydrogel microcapsules can be extracted into the aqueous solution by DEP and interfacial tension forces with no trapped oil, while the encapsulated cells are free from electrical damage due to the Faraday cage effect. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SOLVENT EXTRACTION PROCESS FOR PLUTONIUM

DOEpatents

Seaborg, G.T.

1959-04-14

The separation of plutonium from aqueous inorganic acid solutions by the use of a water immiscible organic extractant liquid is described. The plutonium must be in the oxidized state, and the solvents covered by the patent include nitromethane, nitroethane, nitropropane, and nitrobenzene. The use of a salting out agents such as ammonium nitrate in the case of an aqueous nitric acid solution is advantageous. After contacting the aqueous solution with the organic extractant, the resulting extract and raffinate phases are separated. The plutonium may be recovered by any suitable method.

Aqueous solution-chemical derived Nisbnd Al2O3 solar selective absorbing coatings. 2. Wetting agents and spreading of aqueous solutions on aluminum substrate

NASA Astrophysics Data System (ADS)

Li, Zhenxiang; Zhao, Jianxi

2013-03-01

Wettability of aluminum substrate by the aqueous solutions containing ethoxylated alcohol nonionic surfactants C12En- or Triton X-series was studied using dynamic contact angle measurements. The efficiency of wetting was found to strongly depend on the length of polyoxyethylene (POE) chain of C12En- or Triton X surfactants. For C12E4 that has a very short POE chain, it hardly made the aqueous solution spreading over aluminum. The others with a long POE chain were indeed very efficient in promoting the solution spreading. Moreover, all the spreading process could be completed within 10 s. The single-layer Nisbnd Al2O3 coatings were fabricated from the precursor solutions containing C12En- or Triton X surfactants and the reflectance spectra were measured by a UV/vis spectrophotometer equipped with an integrating sphere. The results indicated that the precursor solution with a long POE chain surfactant as wetting agent favored to fabricate a uniform film on the aluminum substrate and therefore to get a high solar absorptance.

Reaction behaviors of decomposition of monocrotophos in aqueous solution by UV and UV/O processes.

PubMed

Ku, Y; Wang, W; Shen, Y S

2000-02-01

The decomposition of monocrotophos (cis-3-dimethoxyphosphinyloxy-N-methyl-crotonamide) in aqueous solution by UV and UV/O(3) processes was studied. The experiments were carried out under various solution pH values to investigate the decomposition efficiencies of the reactant and organic intermediates in order to determine the completeness of decomposition. The photolytic decomposition rate of monocrotophos was increased with increasing solution pH because the solution pH affects the distribution and light absorbance of monocrotophos species. The combination of O(3) with UV light apparently promoted the decomposition and mineralization of monocrotophos in aqueous solution. For the UV/O(3) process, the breakage of the >C=C< bond of monocrotophos by ozone molecules was found to occur first, followed by mineralization by hydroxyl radicals to generate CO(3)(2-), PO4(3-), and NO(3)(-) anions in sequence. The quasi-global kinetics based on a simplified consecutive-parallel reaction scheme was developed to describe the temporal behavior of monocrotophos decomposition in aqueous solution by the UV/O(3) process.

Process for the extraction of technetium from uranium

DOEpatents

Gong, Cynthia-May S.; Poineau, Frederic; Czerwinski, Kenneth R.

2010-12-21

A spent fuel reprocessing method contacts an aqueous solution containing Technetium(V) and uranyl with an acidic solution comprising hydroxylamine hydrochloride or acetohydroxamic acid to reduce Tc(V) to Tc(II, and then extracts the uranyl with an organic phase, leaving technetium(II) in aqueous solution.

ADSORPTION OF CERIUM VALUES FROM AQUEOUS SOLUTIONS

DOEpatents

Roberts, F.P.

1963-08-13

Cerium can be removed from aqueous nitric acid (2 to 13 M) solutions by passing the latter over a PbO/sub 2/-containing anion exchange resin. The cerium is taken up by the resin, while any lanthanides, yttrium, and strontium present remain in the solution. (AEC)

Method for separating water soluble organics from a process stream by aqueous biphasic extraction

DOEpatents

Chaiko, David J.; Mego, William A.

1999-01-01

A method for separating water-miscible organic species from a process stream by aqueous biphasic extraction is provided. An aqueous biphase system is generated by contacting a process stream comprised of water, salt, and organic species with an aqueous polymer solution. The organic species transfer from the salt-rich phase to the polymer-rich phase, and the phases are separated. Next, the polymer is recovered from the loaded polymer phase by selectively extracting the polymer into an organic phase at an elevated temperature, while the organic species remain in a substantially salt-free aqueous solution. Alternatively, the polymer is recovered from the loaded polymer by a temperature induced phase separation (cloud point extraction), whereby the polymer and the organic species separate into two distinct solutions. The method for separating water-miscible organic species is applicable to the treatment of industrial wastewater streams, including the extraction and recovery of complexed metal ions from salt solutions, organic contaminants from mineral processing streams, and colorants from spent dye baths.

Thermodynamic Parameters of the Dissolution of 4-Hydroxy-L-Proline and L-Phenylalanine in Mixed Aqueous Solvents at 298 K

NASA Astrophysics Data System (ADS)

Smirnov, V. I.; Badelin, V. G.

2018-01-01

The enthalpies of solution of 4-hydroxy-L-proline and L-phenylalanine in binary mixed aqueous solvents containing acetonitrile (AN), 1,4-dioxane (1,4-DO), or acetone (AC) at mole fractions of 0 to 0.25 are determined at T = 298.15 K via isothermal calorimetry. The standard enthalpies of solution (Δsol H°) and transfer (Δtr H°) of 4-hydroxy-L-proline and L-phenylalanine from water to mixed aqueous solvents are calculated using the experimental calorimetric data, as are the enthalpy coefficients of paired interactions ( h xy ) between the molecules of the investigated amino acids and the organic solvents. The effects the mixed aqueous solvent composition and the structure of the organic solvent molecules have on the enthalpies of solution and transfer for the investigated amino acids are considered. The correlation between the enthalpy of solution of the amino acids and the electron-donating properties of the organic solvents in the mixed aqueous solvent systems is established.

Process for the synthesis of iron powder

DOEpatents

Not Available

1982-03-06

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder.

Process for the synthesis of iron powder

DOEpatents

Welbon, William W.

1983-01-01

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder.

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

Bass, Jay D.

This project is aimed at experimental characterization of the sound velocities, equations of state (EOS), and derived physical and chemical properties of aqueous solutions and carbon dioxide at extreme pressure and temperature conditions relevant to processes occurring in the interior of the Earth. Chemical transport, phase changes (including melting), fluid-solid reactions, and formation of magmatic liquids at convergent plat boundaries are a key motivation for this project. Research in this area has long been limited by the extreme experimental challenges and lack of data under the appropriate pressure-temperature (P-T) conditions. The vast majority of studies of aqueous geochemistry relevant tomore » terrestrial problems of fluid-rock interactions have been conducted at 0.3 GPa or less, and the widely used Helgeson-Kirkham-Flowers equation of state for aqueous species is applicable only at ~ < 0.5 GPa. These limits are unfortunate because fluid flow and reactions plays a central role in many deeper environments. Recent efforts including our own, have resulted in new experimental techniques that now make it possible to investigate properties of homogeneous and heterogeneous equilibria involving aqueous species and minerals over a much broader range of pressure and temperature appropriate for deep crustal and upper mantle processes involving water-rich fluids. We carried out 1) Brillouin scattering measurements of the equations of state and molar volume of water and carbon dioxide to over 10 GPa and 870K using precise resistance heating of samples under pressure in the diamond anvil cell, and 2) the phase diagrams of the water and CO2, and 3) Exploring new experimental approaches, including CO2 laser heating of samples in a diamond cell, to measurements of sound velocities, EOS, and phase relations by Brillouin scattering to far greater pressures and temperatures.« less

Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity.

PubMed

Roy Chowdhury, Sankhanilay; Witte, Peter T; Blank, Dave H A; Alsters, Paul L; Ten Elshof, Johan E

2006-04-03

The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous gamma-alumina membranes is reported. The recovery of Q(12)[WZn(3)(ZnW(9)O(34))(2)] (Q=[MeN(n-C(8)H(17))(3)](+)) from toluene-based media was quantitative within experimental error, while up to 97 % of Na(12)[WZn(3)(ZnW(9)O(34))(2)] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed.

Use of solid phase extraction (SPE) to evaluate in vitro skin permeation of aescin.

PubMed

Montenegro, L; Carbone, C; Giannone, I; Puglisi, G

2007-05-01

The aim of this work was to evaluate the feasibility of assessing aescin in vitro permeation through human skin by determining the amount of aescin permeated using conventional HPLC procedures after extraction of skin permeation samples by means of solid phase extraction (SPE). Aescin in vitro skin permeation was assessed from aqueous solutions and gels using both Franz-type diffusion cells and flow-through diffusion cells. The SPE method used was highly accurate (mean accuracy 99.66%), highly reproducible (intra-day and inter-day variations lower than 2.3% and 2.2%, respectively) and aescin recovery from normal saline was greater than 99%. The use of Franz-type diffusion cells did not allow us to determine aescin flux values through excised human skin, therefore aescin skin permeation parameters could be calculated only using flow-through diffusion cells. Plotting the cumulative amount of aescin permeated as a function of time, linear relationships were obtained from both aqueous solution and gel using flow-through diffusion cells. Aescin flux values through excised human skin from aqueous gel were significantly lower than those observed from aqueous solution (p < 0.05). Calculating aescin percutaneous absorption parameters we evidenced that aescin partition coefficient was lower from the aqueous gel with respect to the aqueous solution. Therefore, the SPE method used in this study was suitable to determine aescin in vitro skin permeation parameters from aqueous solutions and gels using a conventional HPLC method for the analysis of the skin permeation samples.

21 CFR 163.112 - Breakfast cocoa.

Code of Federal Regulations, 2012 CFR

2012-04-01

... oxide, used as such, or in aqueous solution; (2) Neutralizing agents. Phosphoric acid, citric acid and L-tartaric acid, used as such, or in aqueous solution; (3) Spices, natural and artificial flavorings, and...

21 CFR 163.112 - Breakfast cocoa.

Code of Federal Regulations, 2014 CFR

2014-04-01

... oxide, used as such, or in aqueous solution; (2) Neutralizing agents. Phosphoric acid, citric acid and L-tartaric acid, used as such, or in aqueous solution; (3) Spices, natural and artificial flavorings, and...

21 CFR 163.112 - Breakfast cocoa.

Code of Federal Regulations, 2013 CFR

2013-04-01

... oxide, used as such, or in aqueous solution; (2) Neutralizing agents. Phosphoric acid, citric acid and L-tartaric acid, used as such, or in aqueous solution; (3) Spices, natural and artificial flavorings, and...

Homogenization Theory for the Prediction of Obstructed Solute Diffusivity in Macromolecular Solutions

PubMed Central

Donovan, Preston; Chehreghanianzabi, Yasaman; Rathinam, Muruhan; Zustiak, Silviya Petrova

2016-01-01

The study of diffusion in macromolecular solutions is important in many biomedical applications such as separations, drug delivery, and cell encapsulation, and key for many biological processes such as protein assembly and interstitial transport. Not surprisingly, multiple models for the a-priori prediction of diffusion in macromolecular environments have been proposed. However, most models include parameters that are not readily measurable, are specific to the polymer-solute-solvent system, or are fitted and do not have a physical meaning. Here, for the first time, we develop a homogenization theory framework for the prediction of effective solute diffusivity in macromolecular environments based on physical parameters that are easily measurable and not specific to the macromolecule-solute-solvent system. Homogenization theory is useful for situations where knowledge of fine-scale parameters is used to predict bulk system behavior. As a first approximation, we focus on a model where the solute is subjected to obstructed diffusion via stationary spherical obstacles. We find that the homogenization theory results agree well with computationally more expensive Monte Carlo simulations. Moreover, the homogenization theory agrees with effective diffusivities of a solute in dilute and semi-dilute polymer solutions measured using fluorescence correlation spectroscopy. Lastly, we provide a mathematical formula for the effective diffusivity in terms of a non-dimensional and easily measurable geometric system parameter. PMID:26731550

Method for gettering organic, inorganic and elemental iodine in aqueous solutions

DOEpatents

Beahm, Edward C.; Shockley, William E.

1990-07-03

A process for the removal of iodine from aqueous solutions, particularly the trapping of radioactive iodine to mitigate damage resulting from accidents or spills associated with nuclear reactors, by exposing the solution to well dispersed silver carbonate which reacts with the iodine and iodides, thereby gettering iodine and iodine compounds from solution. The iodine is not only removed from solution but also from the contiguous vapor.

Method for gettering organic, inorganic and elemental iodine in aqueous solutions

DOEpatents

Beahm, Edward C.; Shockley, William E.

1990-01-01

A process for the removal of iodine from aqueous solutions, particularly the trapping of radioactive iodine to mitigate damage resulting from accidents or spills associated with nuclear reactors, by exposing the solution to well dispersed silver carbonate which reacts with the iodine and iodides, thereby gettering iodine and iodine compounds from solution. The iodine is not only removed from solution but also from the contiguous vapor.

Crystal growth in fused solvent systems

NASA Technical Reports Server (NTRS)

Ulrich, D. R.; Noone, M. J.; Spear, K. E.; White, W. B.; Henry, E. C.

1973-01-01

Research is reported on the growth of electronic ceramic single crystals from solution for the future growth of crystals in a microgravity environment. Work included growth from fused or glass solvents and aqueous solutions. Topics discussed include: crystal identification and selection; aqueous solution growth of triglycine sulphate (TGS); and characterization of TGS.

MODELING SMALL-SCALE SPILLS OF AQUEOUS SOLUTIONS IN THE INDOOR ENVIRONMENT

EPA Science Inventory

A mass transfer model is proposed to estimate the rates of chemical emissions from aqueous solutions spilled on hard surfaces inside buildings. The model is presented in two forms: a set of four ordinary differential equations and a simplified exact solution. The latter can be ...

Rheological characterization of solutions and thin films made from amylose-hexadecylammonium chloride inclusion complexes and polyvinyl alcohol

USDA-ARS?s Scientific Manuscript database

The rheological properties of aqueous solutions and films made from blends of polyvinyl alcohol (PVOH) and amylose-hexadecylammonium chloride inclusion complexes (Hex-Am) were investigated to better understand the polymer interactions and processing parameters. Aqueous solutions of Hex-Am displayed ...

Study on Latent Heat of Fusion of Ice in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Kumano, Hiroyuki; Asaoka, Tatsunori; Saito, Akio; Okawa, Seiji

In this study, latent heat of fusion of ice in aqueous solutions was measured to understand latent heat of fusion of ice slurries. Propylene glycol, ethylene glycol, ethanol, NaCl and NaNO3 solutions were examined as the aqueous solutions. In the measurement, pure ice was put into the solution, and the temperature variation of the solution due to the melting of the ice was measured. Then, the effective latent heat of fusion was calculated from energy balance equation. When ice melts in solution, the concentration of the solution varies due to the melting of the ice, and dilution heat must be considered. Therefore, the latent heat of fusion of ice in aqueous solutions was predicted by considering the effects of dilution and freezing-point depression. The latent heat of fusion was also measured by differential scanning calorimetry(DSC) to compare the results obtained from the experiments with that obtained by DSC. As the result, it was found that the effective latent heat of fusion of ice decreased with the increase of the concentration of solution, and the effective latent heat of fusion was calculated from latent heat of fusion of pure ice and the effects of freezing-point depression and the dilution heat.

V6O13 films by control of the oxidation state from aqueous precursor to crystalline phase.

PubMed

Peys, Nick; Ling, Yun; Dewulf, Daan; Gielis, Sven; De Dobbelaere, Christopher; Cuypers, Daniel; Adriaensens, Peter; Van Doorslaer, Sabine; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

2013-01-28

An aqueous deposition process for V(6)O(13) films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance ((51)V-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) complexes by Electron Paramagnetic Resonance (EPR) and Fourier Transform Infra-Red (FTIR) spectroscopy. This precursor is successfully employed for the deposition of uniform, thin films. The optimal deposition and annealing conditions for the formation of crystalline V(6)O(13), including the control of the vanadium oxidation state, are determined through an elaborate study of processing temperature and O(2) partial pressure. To ensure a sub 100 nm adjustable film thickness, a non-oxidative intermediate thermal treatment is carried out at the end of each deposition cycle, allowing maximal precursor decomposition while still avoiding V(IV) oxidation. The resulting surface hydrophilicity, indispensable for the homogeneous deposition of the next layer, is explained by an increased surface roughness and the increased availability of surface vanadyl groups. Crystalline V(6)O(13) with a preferential (002) orientation is obtained after a post deposition annealing in a 0.1% O(2) ambient for thin films with a thickness of 20 nm.

Manganese dioxide decoration of macroscopic carbon nanotube fibers: From high-performance liquid-based to all-solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Pendashteh, Afshin; Senokos, Evgeny; Palma, Jesus; Anderson, Marc; Vilatela, Juan J.; Marcilla, Rebeca

2017-12-01

Supercapacitors capable of providing high voltage, energy and power density but yet light, low volume occupying, flexible and mechanically robust are highly interesting and demanded for portable applications. Herein, freestanding flexible hybrid electrodes based on MnO2 nanoparticles grown on macroscopic carbon nanotube fibers (CNTf-MnO2) were fabricated, without the need of any metallic current collector. The CNTf, a support with excellent electrical conductivity, mechanical stability, and appropriate pore structure, was homogeneously decorated with porous akhtenskite ɛ-MnO2 nanoparticles produced via electrodeposition in an optimized organic-aqueous mixture. Electrochemical properties of these decorated fibers were evaluated in different electrolytes including a neutral aqueous solution and a pure 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid (PYR14TFSI). This comparison helps discriminate the various contributions to the total capacitance: (surface) Faradaic and non-Faradaic processes, improved wetting by aqueous electrolytes. Accordingly, symmetric supercapacitors with PYR14TFSI led to a high specific energy of 36 Wh· kgMnO2-1 (16 Wh·kg-1 including the weight of CNTf) and real specific power of 17 kW· kgMnO2-1 (7.5 kW kg-1) at 3.0 V with excellent cycling stability. Moreover, flexible all solid-state supercapacitors were fabricated using PYR14TFSI-based polymer electrolyte, exhibiting maximum energy density of 21 Wh·kg-1 and maximum power density of 8 kW kg-1 normalized by total active material.

Direct Detection of Aqueous CO2 by Infrared Waveguide Spectroscopy with an Amorphous Fluoropolymer Coating Rod.

PubMed

Hotta, Hiroki; Miki, Yuko; Kawaguchi, Yukiko; Tsunoda, Kin-Ichi; Nakaoka, Atsuko; Ko, Sho; Kimoto, Takashi

2017-01-01

Infrared waveguide spectroscopy using a sapphire rod coated with an amorphous fluoropolymer (Cytop, Asahi Glass Co., ltd, Japan) has been developed in order to directly observe CO 2 in aqueous solutions. Since the amorphous fluoropolymer has a relatively high gas-permeability and hydrophobic feature, the aqueous CO 2 transmits into the amorphous fluoropolymer coating film, but water cannot penetrate into the film. Good linearity of calibration curves for CO 2 in the gas and the aqueous solution were obtained.

POLONIUM SEPARATION PROCESS

DOEpatents

Karraker, D.G.

1959-07-14

A liquid-liquid extraction process is presented for the recovery of polonium from lead and bismuth. According to the invention an acidic aqueous chloride phase containing the polonium, lead, and bismuth values is contacted with a tributyl phosphate ether phase. The polonium preferentially enters the organic phase which is then separated and washed with an aqueous hydrochloric solution to remove any lead or bismuth which may also have been extracted. The now highly purified polonium in the organic phase may be transferred to an aqueous solution by extraction with aqueous nitric acid.

Microbial solubilization of phosphate

DOEpatents

Rogers, R.D.; Wolfram, J.H.

1993-10-26

A process is provided for solubilizing phosphate from phosphate containing ore by treatment with microorganisms which comprises forming an aqueous mixture of phosphate ore, microorganisms operable for solubilizing phosphate from the phosphate ore and maintaining the aqueous mixture for a period of time and under conditions operable to effect the microbial solubilization process. An aqueous solution containing soluble phosphorus can be separated from the reacted mixture by precipitation, solvent extraction, selective membrane, exchange resin or gravity methods to recover phosphate from the aqueous solution. 6 figures.

Microbial solubilization of phosphate

DOEpatents

Rogers, Robert D.; Wolfram, James H.

1993-01-01

A process is provided for solubilizing phosphate from phosphate containing ore by treatment with microorganisms which comprises forming an aqueous mixture of phosphate ore, microorganisms operable for solubilizing phosphate from the phosphate ore and maintaining the aqueous mixture for a period of time and under conditions operable to effect the microbial solubilization process. An aqueous solution containing soluble phosphorous can be separated from the reacted mixture by precipitation, solvent extraction, selective membrane, exchange resin or gravity methods to recover phosphate from the aqueous solution.

Relation between the adsorbed quantity and the immersion enthalpy in catechol aqueous solutions on activated carbons.

PubMed

Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

2012-01-01

An activated carbon, Carbochem(TM)-PS230, was modified by chemical and thermal treatment in flow of H(2), in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pK(a). The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g(-1) for catechol aqueous solutions in a range of 20 at 1500 mg·L(-1).

Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

PubMed Central

Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

2012-01-01

An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g−1 for catechol aqueous solutions in a range of 20 at 1500 mg·L−1. PMID:22312237

75 FR 30844 - General Mills, Inc.; Withdrawal of Food Additive Petition

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-02

... for the reduction of pathogens and other microorganisms in aqueous sugar solutions and potable water... reduction of pathogens and other microorganisms in aqueous sugar solutions and potable water intended for...

Structural characterization of metal complexes in aqueous solutions: a XAS study of stannous fluoride

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

Alsina, Marco A.; Gaillard, Jean-François

The identity and structure of tin(ii)-fluoride complexes formed in aqueous solutions are determined by combining X-ray absorption spectroscopy, thermodynamic modeling and quantum mechanical calculations.

Biomass carbon composited FeS2 as cathode materials for high-rate rechargeable lithium-ion battery

NASA Astrophysics Data System (ADS)

Xu, Xin; Meng, Zhen; Zhu, Xueling; Zhang, Shunlong; Han, Wei-Qiang

2018-03-01

Pyrite FeS2 has long been used as commercial primary lithium batteries at room temperature. To achieve rechargeable FeS2 battery, biomass-carbon@FeS2 composites are prepared using green and renewable auricularia auricula as carbon source through the process of carbonization and sulfuration. The auricularia auricula has strong swelling characteristics to absorb aqueous solution which can effectively absorb Fe ions into its body. FeS2 homogeneously distributed in biomass carbon matrix performs high electronic and ionic conductivity. The specific capacity of biomass-carbon@FeS2 composites remains 850 mAh g-1 after 80 cycles at 0.5C and 700 mAh g-1 at the rate of 2C after 150 cycles. Biomass-carbon@FeS2 composites exhibit high-rate capacity in lithium-ion battery.

Transparent sunlight conversion film based on carboxymethyl cellulose and carbon dots.

PubMed

You, Yaqin; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

2016-10-20

Transparent sunlight conversion film based on carboxymethyl cellulose (CMC) and carbon dots (CDs) has been developed for the first time through dispersion of CDs in CMC aqueous solution. Due to the hydrogen bonds interaction, CMC can effectively absorb the CDs, whose surfaces are functionalized by lots of polar groups. The results from atomic force microscopy (AFM), scanning electron microscopy (SEM) confirm that the composite film possesses a homogeneous and compact structure. Besides, the CMC matrix neither competes for absorbing excitation light nor absorbs the emissions of CDs, which reserves the inherent optical properties of the individual CDs. The composite films can efficiently convert ultraviolet light to blue light. What's more, the film is transparent and possesses excellent mechanical properties, expected to apply in the field of agricultural planting for sunlight conversion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sorption of ochratoxin A from aqueous solutions using β-cyclodextrin-polyurethane polymer.

PubMed

Appell, Michael; Jackson, Michael A

2012-02-01

The ability of a cyclodextrin-polyurethane polymer to remove ochratoxin A from aqueous solutions was examined by batch rebinding assays. The results from the aqueous binding studies were fit to two parameter models to gain insight into the interaction of ochratoxin A with the nanosponge material. The ochratoxin A sorption data fit well to the heterogeneous Freundlich isotherm model. The polymer was less effective at binding ochratoxin A in high pH buffer (9.5) under conditions where ochratoxin A exists predominantly in the dianionic state. Batch rebinding assays in red wine indicate the polymer is able to remove significant levels of ochratoxin A from spiked solutions between 1-10 μg·L(-1). These results suggest cyclodextrin nanosponge materials are suitable to reduce levels of ochratoxin A from spiked aqueous solutions and red wine samples.

Superlubricity of a Mixed Aqueous Solution

NASA Astrophysics Data System (ADS)

Ma, Zhi-Zuo; Zhang, Chen-Hui; Luo, Jian-Bin; Lu, Xin-Chun; Wen, Shi-Zhu

2011-05-01

A super-low friction coefficient of 0.0028 is measured under a pressure of 300 MPa when the friction pair (the silicon nitride ball sliding on the silicate glass) is lubricated by the mixed aqueous solution of glycerol and boric acid. The morphorlogies of the hydroxylated glass plate are observed by an atomic force microscope (AFM) in deionized water, glycerol, boric acid and their mixed aqueous solution. Bonding peaks of the retained liquids adhered on the surface of the sliding track are detected by an infrared spectrum apparatus and a Raman spectrum apparatus. The mechanism of the superlubricity of the glycerol and boric acid mixed aqueous solution is discussed. It is deduced that the formation of the lubricant film has enough strength to support higher loads, the hydration effect offering the super lower shear resistance. Key words: superlubricity, water based lubricant, ultra-low friction

Separation and concentration of lower alcohols from dilute aqueous solutions

DOEpatents

Moore, Raymond H.; Eakin, David E.; Baker, Eddie G.; Hallen, Richard T.

1991-01-01

A process for producing, from a dilute aqueous solution of a lower (C.sub.1 -C.sub.5) alcohol, a concentrated liquid solution of the alcohol in an aromatic organic solvent is disclosed. Most of the water is removed from the dilute aqueous solution of alcohol by chilling sufficiently to form ice crystals. Simultaneously, the remaining liquid is extracted at substantially the same low temperature with a liquid organic solvent that is substantially immiscible in aqueous liquids and has an affinity for the alcohol at that temperature, causing the alcohol to transfer to the organic phase. After separating the organic liquid from the ice crystals, the organic liquid can be distilled to enrich the concentration of alcohol therein. Ethanol so separated from water and concentrated in an organic solvent such as toluene is useful as an anti-knock additive for gasoline.

Methods for separating medical isotopes using ionic liquids

DOEpatents

Luo, Huimin; Boll, Rose Ann; Bell, Jason Richard; Dai, Sheng

2014-10-21

A method for extracting a radioisotope from an aqueous solution, the method comprising: a) intimately mixing a non-chelating ionic liquid with the aqueous solution to transfer at least a portion of said radioisotope to said non-chelating ionic liquid; and b) separating the non-chelating ionic liquid from the aqueous solution. In preferred embodiments, the method achieves an extraction efficiency of at least 80%, or a separation factor of at least 1.times.10.sup.4 when more than one radioisotope is included in the aqueous solution. In particular embodiments, the method is applied to the separation of medical isotopes pairs, such as Th from Ac (Th-229/Ac-225, Ac-227/Th-227), or Ra from Ac (Ac-225 and Ra-225, Ac-227 and Ra-223), or Ra from Th (Th-227 and Ra-223, Th-229 and Ra-225).

Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

NASA Astrophysics Data System (ADS)

Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

2016-04-01

Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

Heat capacity of alkanolamine aqueous solutions

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

Chiu, L.F.; Li, M.H.

1999-12-01

Heat capacities of monoethanoloamine, diglycolamine, diethanolamine, di-w propanolamine, triethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-l-propanol, and 2-piperidineethanol aqueous solutions were measured from 30 to 80 C with a differential scanning calorimeter (DSC). The mole fractions of alkanolamines studied are 0.2, 0.4, 0.6, and 0.8. Heat capacities of N-methyldiethanolamine aqueous solutions have been measured to verify the validity of C{sub p} measurements for alkanolamine aqueous solutions. The estimated uncertainty of the measured heat capacities is {plus{underscore}minus}3%, including the effect of up to 5% impurities in a substance. An excess molar heat capacity expression using the Redlich-Kister equation for the composition dependence is used to representmore » the measured C{sub p} of alkanolamine aqueous solutions. For a total of 374 data points, the calculation results for eight alkanolamine solutions give the overall average absolute deviations of 11.9% and 0.29% for the excess molar heat capacity and the heat capacity, respectively. The heat capacities presented in this study are, in general, of sufficient accuracy for most engineering-design calculations. Solutions of alkanolamines are industrially important mixtures used in the natural gas industry, oil refineries, petroleum chemical plants, and synthetic ammonia plants for the removal of acidic components such as CO{sub 2} and H{sub 2}S from gas streams.« less

METHOD OF APPLYING COPPER COATINGS TO URANIUM

DOEpatents

Gray, A.G.

1959-07-14

A method is presented for protecting metallic uranium, which comprises anodic etching of the uranium in an aqueous phosphoric acid solution containing chloride ions, cleaning the etched uranium in aqueous nitric acid solution, promptly electro-plating the cleaned uranium in a copper electro-plating bath, and then electro-plating thereupon lead, tin, zinc, cadmium, chromium or nickel from an aqueous electro-plating bath.

Method of making metal oxide ceramic powders by using a combustible amino acid compound

DOEpatents

Pederson, L.R.; Chick, L.A.; Exarhos, G.J.

1992-05-19

This invention is directed to the formation of homogeneous, aqueous precursor mixtures of at least one substantially soluble metal salt and a substantially soluble, combustible co-reactant compound, typically an amino acid. This produces, upon evaporation, a substantially homogeneous intermediate material having a total solids level which would support combustion. The homogeneous intermediate material essentially comprises highly dispersed or solvated metal constituents and the co-reactant compound. The intermediate material is quite flammable. A metal oxide powder results on ignition of the intermediate product which combusts same to produce the product powder.

Method of making metal oxide ceramic powders by using a combustible amino acid compound

DOEpatents

Pederson, Larry R.; Chick, Lawrence A.; Exarhos, Gregory J.

1992-01-01

This invention is directed to the formation of homogeneous, aqueous precursor mixtures of at least one substantially soluble metal salt and a substantially soluble, combustible co-reactant compound, typically an amino acid. This produces, upon evaporation, a substantially homogeneous intermediate material having a total solids level which would support combustion. The homogeneous intermediate material essentially comprises highly dispersed or solvated metal constituents and the co-reactant compound. The intermediate material is quite flammable. A metal oxide powder results on ignition of the intermediate product which combusts same to produce the product powder.

Pre-formulation and chemical stability studies of penethamate, a benzylpenicillin ester prodrug, in aqueous vehicles.

PubMed

Jain, Rohit; Wu, Zimei; Bork, Olaf; Tucker, Ian G

2012-01-01

Penethamate (PNT) is a diethylaminoethyl ester prodrug of benzylpenicillin used to treat bovine mastitis via the intramuscular route. Because of its instability, PNT products must be reconstituted before administration and the reconstituted injection has a short shelf life (7 days at 2-8°C). The purpose of this paper was to investigate whether the stability of PNT can be improved in order to achieve a chemically stable ready-to-use aqueous-based PNT formulation or at least to extend the shelf life of the reconstituted suspension. A chemical stability study of PNT in aqueous-based solutions as a function of pH, buffer strength, solvent mixtures and temperature, supported by studies of its solubility in mixed solvents, allowed predictions of the shelf life of PNT solution and suspension formulations. PNT degraded in aqueous solutions by several pathways over the pH range 2.0-9.3 with a V-shaped pH-rate profile and a minimum pH of around 4.5. The stability of PNT solutions in mixed solvents was greater than in aqueous solutions. For example, in propylene glycol:citrate buffer (60:40, v/v, pH 4.5), the half-life of PNT was 4.3 days compared with 1.8 days in aqueous buffer. However, solubility of PNT in the mixed solvent was higher than that in aqueous solution and this had an adverse effect on the stability of suspensions. By judicious choosing of pH and mixed solvent, it is possible to achieve a storage life of a PNT suspension of 5.5 months at 5°C, not sufficient for a ready-to-use product but a dramatic improvement in the storage life of the reconstituted product.

Design and Construction of Experiment for Direct Electron Irradiation of Uranyl Sulfate Solution: Bubble Formation and Thermal Hydraulics Studies

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

Chemerisov, Sergey; Gromov, Roman; Makarashvili, Vakho

Argonne is assisting SHINE Medical Technologies in developing SHINE, a system for producing fission-product 99Mo using a D/T-accelerator to produce fission in a non-critical target solution of aqueous uranyl sulfate. We have developed an experimental setup for studying thermal-hydraulics and bubble formation in the uranyl sulfate solution to simulate conditions expected in the SHINE target solution during irradiation. A direct electron beam from the linac accelerator will be used to irradiate a 20 L solution (sector of the solution vessel). Because the solution will undergo radiolytic decomposition, we will be able to study bubble formation and dynamics and effects ofmore » convection and temperature on bubble behavior. These experiments will serve as a verification/ validation tool for the thermal-hydraulic model. Utilization of the direct electron beam for irradiation allows homogeneous heating of a large solution volume and simplifies observation of the bubble dynamics simultaneously with thermal-hydraulic data collection, which will complement data collected during operation of the miniSHINE experiment. Irradiation will be conducted using a 30-40 MeV electron beam from the high-power linac accelerator. The total electron-beam power will be 20 kW, which will yield a power density on the order of 1 kW/L. The solution volume will be cooled on the front and back surfaces and central tube to mimic the geometry of the proposed SHINE solution vessel. Also, multiple thermocouples will be inserted into the solution vessel to map thermal profiles. The experimental design is now complete, and installation and testing are in progress.« less

Desorption of CO{sub 2} from MDEA and activated MDEA solutions

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

Xu, G.W.; Zhang, C.F.; Qin, S.J.

1995-03-01

A packed column was used for investigating the desorption rate of CO{sub 2} from aqueous methyldiethanolamine (MDEA) and activated MDEA solutions. Experiments were conducted within the temperature range 30--70 C, the concentration of MDEA was 4.28 kmol/m{sup 3}, and the concentration of piperazine (PZ) was 0.10 kmol/m{sup 3} for aqueous activated MDEA solutions. Experimental data confirmed that the kinetics model of absorption CO{sub 2} into aqueous MDEA and activated MDEA solutions can be applicable to the situations in which desorption occurs, and the desorption rate of model predictions agree well with that of experimental determination.

Separation of metal ions from aqueous solutions

DOEpatents

Almon, Amy C.

1994-01-01

A process and apparatus for quantitatively and selectively separating metal ions from mixtures thereof in aqueous solution. The apparatus includes, in combination, a horizontal electrochemical flow cell containing flow bulk electrolyte solution and an aqueous, metal ion-containing solution, the cell containing a metal mesh working electrode, a counter electrode positioned downstream from the working electrode, an independent variable power supply/potentiostat positioned outside of the flow cell and connected to the electrodes, and optionally a detector such as a chromatographic detector, positioned outside the flow cell. This apparatus and its operation has significant application where trace amounts of metal ions are to be separated.

Calculating the thermodynamic properties of aqueous solutions of alkali metal carboxylates

NASA Astrophysics Data System (ADS)

Rudakov, A. M.; Sergievskii, V. V.; Zhukova, T. V.

2014-06-01

A modified Robinson-Stokes equation with terms that consider the formation of ionic hydrates and associates is used to describe thermodynamic properties of aqueous solutions of electrolytes. The model is used to describe data on the osmotic coefficients of aqueous solutions of alkali metal carboxylates, and to calculate the mean ionic activity coefficients of salts and excess Gibbs energies. The key contributions from ionic hydration and association to the nonideality of solutions is determined by analyzing the contributions of various factors. Relations that connect the hydration numbers of electrolytes with the parameters of the Pitzer-Mayorga equation and a modified Hückel equation are developed.

A Modified Robinson-Stokes equation for describing the thermodynamic properties of aqueous solutions of 1-1 electrolytes

NASA Astrophysics Data System (ADS)

Rudakov, A. M.; Sergievskii, V. V.

2008-05-01

Equations relating osmotic, mean ionic activity, and water activity coefficients to electrolyte concentrations in binary aqueous solutions were substantiated within the framework of cluster concepts. The model includes the contribution to solution nonideality of electrostatic interactions in terms of the Debye-Hückel theory along with hydration and association of salts via relations containing hydration and association numbers in the standard states. According to the description of data on 54 aqueous solutions of 1-1 electrolytes, this model should be given preference compared with the most extensively used NRTL, NRTL-NRF, Wilson, and Pitzer models.

Heat-induced morphological transformation of gold nanodumbbells in ionic surfactant solutions

NASA Astrophysics Data System (ADS)

Wen, Ting-Chun; Lu, Chung-Wen; Hsieh, Wei-Chi; Chang, Sheng-Te; Yang, Ya-Ting; Deng, Jin-Pei

2018-01-01

The thermal stability of gold nanodumbbells (NDs) is studied in aqueous solution of ionic surfactants. It is found in aqueous solution of cetyltrimethylammonium bromide that the blue-shift of longitudinal surface plasmon resonance band of gold NDs occurs at 75 °C and the new gold nanorods (NRs) with shortened aspect ratio are formed at the same time. The aspect ratio of the generated gold NRs gradually decreases and finally approaches ∼1.7 after repeated processing. Similarly, the same results are also obtained in aqueous solution of sodium dodecyl sulfate at room temperature. Mechanism is proposed for the shape transformation of gold NDs.

Laboratory studies of aqueous-phase oxidation of polyols in submicron particles

NASA Astrophysics Data System (ADS)

Daumit, K. E.; Carrasquillo, A. J.; Hunter, J. F.; Kroll, J. H.

2013-12-01

Aqueous-phase oxidation has received recent attention as a potential pathway for the formation of highly oxidized organic aerosol. However most aqueous oxidation studies are performed in bulk solutions rather than aqueous droplets. Here we describe experiments in which aqueous oxidation is carried out within submicron particles, allowing for gas-particle partitioning of reactants, intermediates, and products. Using Fenton chemistry as a source of hydroxyl radicals, and a high-resolution aerosol mass spectrometer (AMS) for online characterization of particle composition, we find that aqueous oxidation can be quite rapid. The formation of high concentrations of oxalic acid is observed in the particle phase with some loss of carbon to the gas phase, indicating the formation of volatile products. We see a rapid degradation of condensed-phase oxidation products upon exposure to ultraviolet lights (centered at 350 nm) suggesting that these products may exist as iron(III)-oxalate complexes. Similar results are also seen when oxidation is carried out in bulk solution (with AMS analysis of the atomized solution); however in some cases the mass loss is less than is observed for submicron particles, likely due to differences in partitioning of early-generation products. Such products can partition out of the aqueous phase at the low liquid water contents in the chamber but remain in solution for further aqueous processing in bulk oxidation experiments. This work suggests that the product distributions from oxidation in aqueous aerosol may be substantially different than those in bulk oxidation, pointing to the need to carry out aqueous oxidation studies under atmospherically relevant partitioning conditions (with liquid water contents mimicking those of cloud droplets or wet aerosol).

An ex vivo human aqueous humor-concentration comparison of two commercial bromfenac formulations

PubMed Central

Walters, Thomas R; Smyth-Medina, Robert J; Cockrum, Paul C

2018-01-01

Purpose The purpose of this study was to quantify the concentration of bromfenac in the aqueous humor utilizing high-performance liquid chromatography mass spectrometry between two commercial nonsteroidal anti-inflammatory drugs, using aqueous humor concentrations to characterize pharmacokinetic proportional differences between 0.075% bromfenac ophthalmic solution in DuraSite (BromSite®) and 0.09% bromfenac ophthalmic solution (Bromday®). Methods In this multicenter, randomized, double-masked, two-arm, parallel-group, comparative, Phase II clinical trial, subjects were assigned to receive bromfenac in DuraSite or bromfenac ophthalmic solution in a 1:1 ratio. One drop of the masked test article was instilled into the study eye once a day for 2 days prior to and 3 hours prior (last instillation) to the subject’s cataract surgery. Aqueous humor samples were collected upon initial cataract incision for analysis of bromfenac levels. The primary end point was aqueous humor concentration of bromfenac at Day 3, at the initiation of cataract surgery. Aqueous humor samples were collected and analyzed for bromfenac levels. Results A total of 60 subjects completed the study, 30 in each group. The mean bromfenac aqueous humor concentration in subjects who received bromfenac in DuraSite was more than twice (49.33±41.87 ng/mL, P=0.004) that of subjects who received bromfenac ophthalmic solution (23.65±16.31 ng/mL) after three doses. Conclusion Mean bromfenac aqueous humor concentration in subjects receiving the DuraSite-containing bromfenac in DuraSite (0.075%) was significantly higher compared to subjects receiving bromfenac ophthalmic solution (0.09%) after 3 days of dosing. PMID:29849449

Covering surface nanobubbles with a NaCl nanoblanket.

PubMed

Berkelaar, Robin P; Zandvliet, Harold J W; Lohse, Detlef

2013-09-10

By letting a NaCl aqueous solution of low (0.01 M) concentration evaporate on a highly oriented pyrolytic graphite (HOPG) surface, it is possible to form a thin film of salt. However, pre-existing surface nanobubbles prevent the homogeneous coverage of the surface with the salt, keeping the footprint areas on the substrate pristine. Comparing the surface nanobubbles in the salt solution with their associated footprint after drying, provides information on the shrinkage of nanobubbles during the hours-long process of drying the liquid film. At a slightly higher NaCl concentration and thus salt layer thickness, the nanobubbles are covered with a thin blanket of salt. Once the liquid film has evaporated until a water film remains that is smaller than the height of the nanobubbles, the blanket of salt cracks and unfolds into a flower-like pattern of salt flakes that is located at the rim of the nanobubble footprint. The formation of a blanket of salt covering the nanobubbles is likely to considerably or even completely block the gas out-flux from the nanobubble, partially stabilizing the nanobubbles against dissolution.

Immersion freezing of water and aqueous ammonium sulfate droplets initiated by humic-like substances as a function of water activity

DOE PAGES

Rigg, Y. J.; Alpert, P. A.; Knopf, Daniel A.

2013-07-12

Immersion freezing of water and aqueous (NH 4) 2SO 4 droplets containing leonardite (LEO) and Pahokee peat (PP) serving as surrogates for humic-like substances (HULIS) has been investigated. Organic aerosol containing HULIS are ubiquitous in the atmosphere; however, their potential for ice cloud formation is uncertain. Immersion freezing has been studied for temperatures as low as 215K and solution water activity, aw, from 0.85 to 1.0. The freezing temperatures of water and aqueous solution droplets containing LEO and PP are 5–15 K warmer than homogeneous ice nucleation temperatures. Heterogeneous freezing temperatures can be represented by a horizontal shift of themore » ice melting curve as a function of solution aw by Δ aw = 0.2703 and 0.2466, respectively. Corresponding heterogeneous ice nucleation rate coefficients, Jhet, are (9.6 ± 2.5) × 10 4 and (5.4 ± 1.4) × 10 4 cm -2 s -1 for LEO and PP containing droplets, respectively, and remain constant along freezing curves characterized by Δ aw. Consequently predictions of freezing temperatures and kinetics can be made without knowledge of the solute type when relative humidity and ice nuclei (IN) surface areas are known. The acquired ice nucleation data are applied to evaluate different approaches to fit and reproduce experimentally derived frozen fractions. In addition, we apply a basic formulation of classical nucleation theory (α( T)-model) to calculate contact angles and frozen fractions. Contact angles calculated for each ice nucleus as a function of temperature, α( T)-model, reproduce exactly experimentally derived frozen fractions without involving free-fit parameters. However, assigning the IN a single contact angle for the entire population (single-α model) is not suited to represent the frozen fractions. Application of α-PDF, active sites, and deterministic model approaches to measured frozen fractions yield similar good representations. Furthermore, when using a single parameterization of α-PDF or active sites distribution to fit all individual aw immersion freezing data simultaneously, frozen fraction curves are not reproduced. This implies that these fitting formulations cannot be applied to immersion freezing of aqueous solutions, and suggests that derived fit parameters do not represent independent particle properties. Thus, from fitting frozen fractions only, the underlying ice nucleation mechanism and nature of the ice nucleating sites cannot be inferred. In contrast to using fitted functions obtained to represent experimental conditions only, we suggest to use experimentally derived Jhet as a function of temperature and aw that can be applied to conditions outside of those probed in laboratory. Finally, this is because Jhet(T) is independent of time and IN surface areas in contrast to the fit parameters obtained by representation of experimentally derived frozen fractions.« less

Theoretic Study on Dispersion Mechanism of Boron Nitride Nanotubes by Polynucleotides

PubMed Central

Liang, Lijun; Hu, Wei; Zhang, Zhisen; Shen, Jia-Wei

2016-01-01

Due to the unique electrical and mechanical properties of boron nitride nanotubes (BNNT), BNNT has been a promising material for many potential applications, especially in biomedical field. Understanding the dispersion of BNNT in aqueous solution by biomolecules is essential for its use in biomedical applications. In this study, BNNT wrapped by polynucleotides in aqueous solution was investigated by molecular dynamics (MD) simulations. Our results demonstrated that the BNNT wrapped by polynucleotides could greatly hinder the aggregation of BNNTs and improve the dispersion of BNNTs in aqueous solution. Dispersion of BNNTs with the assistance of polynucleotides is greatly affected by the wrapping manner of polynucleotides on BNNT, which mainly depends on two factors: the type of polynucleotides and the radius of BNNT. The interaction between polynucleotides and BNNT(9, 9) is larger than that between polynucleotides and BNNT(5, 5), which leads to the fact that dispersion of BNNT(9, 9) is better than that of BNNT(5, 5) with the assistance of polynucleotides in aqueous solution. Our study revealed the molecular-level dispersion mechanism of BNNT with the assistance of polynucleotides in aqueous solution. It shades a light on the understanding of dispersion of single wall nanotubes by biomolecules. PMID:28004832

Photolysis of Diazo Dye in Aqueous Solutions of Metal Nitrates

NASA Astrophysics Data System (ADS)

Volkova, N. A.; Evstrop'ev, S. K.; Istomina, O. V.; Kolobkova, E. V.

2018-04-01

The photolysis of Chicago Blue Sky diazo dye is studied. It is experimentally shown that the presence of metal nitrates in aqueous solutions changes the photolysis mechanism and sharply increases the photolysis rate.

Multiple stimulus reversible hydrogels

DOEpatents

Gutowska, Anna; Krzyminski, Karol J.

2003-12-09

A polymeric solution capable of gelling upon exposure to a critical minimum value of a plurality of environmental stimuli is disclosed. The polymeric solution may be an aqueous solution utilized in vivo and capable of having the gelation reversed if at least one of the stimuli fall below, or outside the range of, the critical minimum value. The aqueous polymeric solution can be used either in industrial or pharmaceutical environments. In the medical environment, the aqueous polymeric solution is provided with either a chemical or radioisotopic therapeutic agent for delivery to a specific body part. The primary advantage of the process is that exposure to one environmental stimuli alone will not cause gelation, thereby enabling the therapeutic agent to be conducted through the body for relatively long distances without gelation occurring.

Multiple stimulus reversible hydrogels

DOEpatents

Gutowska, Anna; Krzyminski, Karol J.

2006-04-25

A polymeric solution capable of gelling upon exposure to a critical minimum value of a plurality of environmental stimuli is disclosed. The polymeric solution may be an aqueous solution utilized in vivo and capable of having the gelation reversed if at least one of the stimuli fall below, or outside the range of, the critical minimum value. The aqueous polymeric solution can be used either in industrial or pharmaceutical environments. In the medical environment, the aqueous polymeric solution is provided with either a chemical or radioisotopic therapeutic agent for delivery to a specific body part. The primary advantage of the process is that exposure to one environmental stimuli alone will not cause gelation, thereby enabling the therapeutic agent to be conducted through the body for relatively long distances without gelation occurring.

Removal of metal ions from aqueous solution

DOEpatents

Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

1990-01-01

A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

Removal of metal ions from aqueous solution

DOEpatents

Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

1990-11-13

A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heayv metals from solution. This also results in the removal of the metals from the column in a concentrated form.

Long-term results of treatment with diquafosol ophthalmic solution for aqueous-deficient dry eye.

PubMed

Koh, Shizuka; Ikeda, Chikako; Takai, Yoshihiro; Watanabe, Hitoshi; Maeda, Naoyuki; Nishida, Kohji

2013-09-01

To evaluate the preliminary long-term efficacy of diquafosol ophthalmic solution for aqueous-deficient dry eye. Fifteen patients with mild-to-moderate aqueous-deficient dry eye were enrolled. After a washout period, the patients were treated with 3 % diquafosol ophthalmic solution for 6 months. We assessed 12 subjective dry eye symptoms, corneal and conjunctival staining with fluorescein, tear film break-up time (BUT), lower tear meniscus height measured with anterior-segment optical coherence tomography, Schirmer's testing, and adverse reactions at baseline and 1, 3, and 6 months after the start of treatment. Treatment with diquafosol ophthalmic solution significantly improved dry eye symptoms, corneal staining, BUT, and tear meniscus height at 1 month and maintained the effectiveness for 6 months. Conjunctival staining significantly improved 3 and 6 months after treatment. No significant adverse reactions developed. Prolonged use of diquafosol ophthalmic solution for 6 months produced significant improvement both subjectively (dry eye symptom score) and objectively (ocular staining score and tear function tests) for aqueous-deficient dry eye.

Coatable Li4 SnS4 Solid Electrolytes Prepared from Aqueous Solutions for All-Solid-State Lithium-Ion Batteries.

PubMed

Choi, Young Eun; Park, Kern Ho; Kim, Dong Hyeon; Oh, Dae Yang; Kwak, Hi Ram; Lee, Young-Gi; Jung, Yoon Seok

2017-06-22

Bulk-type all-solid-state lithium-ion batteries (ASLBs) for large-scale energy-storage applications have emerged as a promising alternative to conventional lithium-ion batteries (LIBs) owing to their superior safety. However, the electrochemical performance of bulk-type ASLBs is critically limited by the low ionic conductivity of solid electrolytes (SEs) and poor ionic contact between the active materials and SEs. Herein, highly conductive (0.14 mS cm -1 ) and dry-air-stable SEs (Li 4 SnS 4 ) are reported, which are prepared using a scalable aqueous-solution process. An active material (LiCoO 2 ) coated by solidified Li 4 SnS 4 from aqueous solutions results in a significant improvement in the electrochemical performance of ASLBs. Side-effects of the exposure of LiCoO 2 to aqueous solutions are minimized by using predissolved Li 4 SnS 4 solution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

METHOD FOR SEPARATION OF PLUTONIUM FROM URANIUM AND FISSION PRODUCTS BY SOLVENT EXTRACTION

DOEpatents

Seaborg, G.T.; Blaedel, W.J.; Walling, M.T. Jr.

1960-08-23

A process is given for separating from each other uranium, plutonium, and fission products in an aqueous nitric acid solution by the so-called Redox process. The plutonium is first oxidized to the hexavalent state, e.g., with a water-soluble dichromate or sodium bismuthate, preferably together with a holding oxidant such as potassium bromate. potassium permanganate, or an excess of the oxidizing agent. The solution is then contacted with a water-immiscible organic solvent, preferably hexone. whereby uranium and plutonium are extracted while the fission products remain in the aqueous solution. The separated organic phase is then contacted with an aqueous solution of a reducing agent, with or without a holding reductant (e.g., with a ferrous salt plus hydrazine or with ferrous sulfamate), whereby plutonium is reduced to the trivalent state and back- extracted into the aqueous solution. The uranium may finally be back-extracted from the organic solvent (e.g., with a 0.1 N nitric acid).

Electronic structure of aqueous solutions: Bridging the gap between theory and experiments.

PubMed

Pham, Tuan Anh; Govoni, Marco; Seidel, Robert; Bradforth, Stephen E; Schwegler, Eric; Galli, Giulia

2017-06-01

Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum mechanical methods. However, it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. We propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, on the basis of the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results of the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecular dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of the electronic properties of the solvent and solutes, including excitation energies. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies.

Electronic structure of aqueous solutions: Bridging the gap between theory and experiments

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

Pham, Tuan Anh; Govoni, Marco; Seidel, Robert

Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum mechanical methods. However, it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. We propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, on the basis of the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results of the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecularmore » dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of the electronic properties of the solvent and solutes, including excitation energies. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies.« less

Mercury removal from aqueous solutions by zinc cementation.

PubMed

Ku, Young; Wu, Ming-Huan; Shen, Yung-Shen

2002-01-01

The main purpose of this research is to study the addition effect of the surfactant and other operating factors on the treatment of wastewater containing mercury ions in aqueous solution by cementation with sacrificing metal, zinc. The removal of mercury ions from aqueous solutions by cementation of zinc powder was found to be a function of solution pH and temperature, amount of zinc, concentration of mercury ion, contact time and the addition of several organic surfactants. Cementation of mercury was shown to be a feasible process to achieve a very high degree of mercury removal over a broad operational range within a fairly reasonable contact time. The reaction rate is approximately first order with respect to the concentration of mercury ion in aqueous solution. Among the surfactants used in this study, only the presence of SDS, an anionic surfactant, slightly enhanced the cementation rate of mercury. The presence of CTAB and Triton-X100 retarded the cementation of mercury by zinc.

Self-Assembly of Porphyrin J-Aggregates

NASA Astrophysics Data System (ADS)

Snitka, Valentinas; Rackaitis, Mindaugas; Navickaite, Gintare

2006-03-01

The porphyrin nanotubes were built by ionic self-assembly of two oppositely charged porphyrins in aqueous solution. The porphyrins in the acid aqueous solution self-assemble into J-aggregates, wheels or other structures. The electrostatic forces between these porphyrin blocks contribute to the formation of porphyrin aggregates in the form of nanotubes, enhance the structural stability of these nanostructures. The nanotubes were composed mixing aqueous solutions of the two porphyrins - anionic Meso-tetra(4- sulfonatophrnyl)porhine dihydrochloride (TPPS4) and cationic Meso-tetra(4-pyridyl)porphine (T4MPyP). The porphyrin nanotubes obtained are hollow structures with the length of 300 nm and diameter 50 nm. Photocatalytic porphyrins are used to reduce metal complexes from aqueous solution and to control the deposition of Au from AuHCl4 and Au nanoparticles colloid solutions onto porphyrin nanotubes. Porphyrin nanotubes are shown to reduce metal complexes and deposit the metal selectively onto the inner or outer surface of the tubes, leading to nanotube-metal composite structures.

Challenges in analysis of high-molar mass dextrans: comparison of HPSEC, AsFlFFF and DOSY NMR spectroscopy.

PubMed

Maina, Ndegwa Henry; Pitkänen, Leena; Heikkinen, Sami; Tuomainen, Päivi; Virkki, Liisa; Tenkanen, Maija

2014-01-01

Dilute solutions of various dextran standards, a high-molar mass (HMM) commercial dextran from Leuconostoc spp., and HMM dextrans isolated from Weissella confusa and Leuconostoc citreum were analyzed with high-performance size-exclusion chromatography (HPSEC), asymmetric flow field-flow fractionation (AsFlFFF), and diffusion-ordered NMR spectroscopy (DOSY). HPSEC analyses were performed in aqueous and dimethyl sulfoxide (DMSO) solutions, while only aqueous solutions were utilized in AsFlFFF and DOSY. The study showed that all methods were applicable to dextran analysis, but differences between the aqueous and DMSO-based solutions were obtained for HMM samples. These differences were attributed to the presence of aggregates in aqueous solution that were less prevalent in DMSO. The study showed that DOSY provides an estimate of the size of HMM dextrans, though calibration standards may be required for each experimental set-up. To our knowledge, this is the first study utilizing these three methods in analyzing HMM dextrans. Copyright © 2013 Elsevier Ltd. All rights reserved.

Final product analysis in the e-beam and gamma radiolysis of aqueous solutions of metoprolol tartrate

NASA Astrophysics Data System (ADS)

Slegers, Catherine; Tilquin, Bernard

2006-09-01

The radiostability of metoprolol tartrate aqueous solutions and the influence of the absorbed dose (0-50 kGy), dose rate (e-beam (EB) vs. gamma ( γ)) and radioprotectors (pharmaceutical excipients) are investigated by HPLC-UV analyses and through computer simulations. The use of radioprotecting excipients is more promising than an increase in the dose rate to lower the degradation of metoprolol tartrate aqueous solutions for applications such as radiosterilization. The decontamination of metoprolol tartrate from waste waters by EB processing appears highly feasible.

Vibrational spectroscopic study of nickel (II) formate, Ni(HCO 2) 2, and its aqueous solution

NASA Astrophysics Data System (ADS)

Edwards, H. G. M.; Knowles, A.

1992-04-01

A vibrational spectroscopic study of nickel (II) formate and its aqueous solution has been made. The vibrations characteristic of a formato—nickel complex have been assigned and it is concluded that the species Ni(HCO 2) +(HCO 2) - exists in the solid state, with monodentate ligand-to-metal bonding. The Raman spectrum of an aqueous solution of nickel (II) formate indicates that complete dissociation of the formato—nickel (II) species occurs to formate ions and nickel (II) hexa-aquo ions. Comparisons are made with other nickel (II) carboxylates.

Selected specific rates of reactions of transients from water in aqueous solution. III. Hydroxyl radical and perhydroxyl radical and their radical ions

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

Ross, F; Ross, A B

1977-01-01

Rates of reactions of OH and HO/sub 2/ with organic and inorganic molecules, ions and transients in aqueous solution have been tabulated, as well as the rates for the corresponding radical ions in aqueous solution (O/sup -/ and O/sub 2//sup -/). Most of the rates have been obtained by radiation chemistry methods, both pulsed and steady-state; data from photochemistry and thermal methods are also included. Rates for over one thousand reactions are listed.

Measurements of Atmospheric Aerosols: Experimental Methods and Results of Measurements off the East Coast of the United States.

DTIC Science & Technology

1983-07-19

Pruppacher and Klett, 1978) 2(rl ’. r R 1 F5S = a,, e (5) where a. is the water activity of the aqueous solution , (r is the surface tension of the droplet...desorption) of ions by the insoluble portion of the particle, which is assumed to be totally submerged in the aqueous solution . We denote the coefficient ...between the saturation ratio S (relative humidity/100) of the air and the equili- brium radius r of an aqueous solution droplet may be expressed as

Patents – Melvin Calvin

Science.gov Websites

plutonium from uranium and fission products in an aqueous acidic solution by use of a chelating agent. The concentration is adjusted to about 1 N bar. The aqueous solution is then contacted with a water-immiscible organic solvent solution and the chelating agent. The chelating agents covered by this invention comprise

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

Bunkin, N F; Shkirin, A V; Burkhanov, I S

Aqueous NaCl solutions with different concentrations have been investigated by dynamic scattering of laser radiation. It is experimentally shown that these solutions contain scattering particles with a wide size distribution in a range of ∼10 – 100 nm. The experimental results indirectly confirm the existence of quasi-stable gas nanobubbles in the bulk of aqueous ionic solutions. (light scattering)

NMR studies of water dynamics during sol-to-gel transition of poly (N-isopropylacrylamide) in concentrated aqueous solution

USDA-ARS?s Scientific Manuscript database

The thermo-sensitive polymer, poly(N-isopropylacrylamide) (PNIPAM) undergoes a coil-to-globule transition in an aqueous solution as the temperature is raised through the lower critical solution temperature. Thus far, little is known about the dynamical states of the water molecules that contribute ...

METHOD FOR ELECTRODEPOSITING POLONIUM

DOEpatents

Wehrmann, R.F.

1960-08-30

The deposition of a thick uniform layer of polonium metal from aqueous solutions can be carried out by electrolyzing an aqueous solution of 1 N hydrofluoric acid containing about 0.13 curie of polonium per cubic centimeter of solution with platinum electrodes and a current density of about 1.2 ma/cm/sup 2/ of cathode surface.

MECHANISTIC ROLES OF SOIL HUMUS AND MINERALS IN THE SORPTION OF NONIONIC ORGANIC COMPOUNDS FROM AQUEOUS AND ORGANIC SOLUTIONS

EPA Science Inventory

Mechanistic roles of soil humus and soil minerals and their contributions to soil sorption of nonionic organic compounds from aqueous and organic solutions are illustrated. Parathion and lindane are used as model solutes on two soils that differ greatly in their humic and mineral...

CO2 as a smart gelator for Pluronic aqueous solutions.

PubMed

Liu, Chengcheng; Mei, Qingqing; Zhang, Jianling; Kang, Xinchen; Peng, Li; Han, Buxing; Xue, Zhimin; Sang, Xinxin; Yang, Xiaogan; Wu, Zhonghua; Li, Zhihong; Mo, Guang

2014-11-25

It was found that CO2 could induce the gelation of Pluronic aqueous solutions, during which the microstructure of the solution transforms from randomly dispersed spherical micelles to cubic close packed micelles. The gelation switched by compressed CO2 has many advantages and can be applied in the synthesis of porous materials.

Method for aqueous radioactive waste treatment

DOEpatents

Bray, L.A.; Burger, L.L.

1994-03-29

Plutonium, strontium, and cesium found in aqueous waste solutions resulting from nuclear fuel processing are removed by contacting the waste solutions with synthetic zeolite incorporating up to about 5 wt % titanium as sodium titanate in an ion exchange system. More than 99.9% of the plutonium, strontium, and cesium are removed from the waste solutions. 3 figures.

Method for aqueous radioactive waste treatment

DOEpatents

Bray, Lane A.; Burger, Leland L.

1994-01-01

Plutonium, strontium, and cesium found in aqueous waste solutions resulting from nuclear fuel processing are removed by contacting the waste solutions with synthetic zeolite incorporating up to about 5 wt % titanium as sodium titanate in an ion exchange system. More than 99.9% of the plutonium, strontium, and cesium are removed from the waste solutions.

Direct evidence on the existence of [Mo132]Keplerate-type species in aqueous solution.

PubMed

Roy, Soumyajit; Planken, Karel L; Kim, Robbert; Mandele, Dexx v d; Kegel, Willem K

2007-10-15

We demonstrate the existence of discrete single molecular [Mo(132)] Keplerate-type clusters in aqueous solution. Starting from a discrete spherical [Mo(132)] cluster, the formation of an open-basket-type [Mo(116)] defect structure is shown for the first time in solution using analytical ultracentrifugation sedimentation velocity experiments.

Water oxidation catalysis with nonheme iron complexes under acidic and basic conditions: homogeneous or heterogeneous?

PubMed

Hong, Dachao; Mandal, Sukanta; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

2013-08-19

Thermal water oxidation by cerium(IV) ammonium nitrate (CAN) was catalyzed by nonheme iron complexes, such as Fe(BQEN)(OTf)2 (1) and Fe(BQCN)(OTf)2 (2) (BQEN = N,N'-dimethyl-N,N'-bis(8-quinolyl)ethane-1,2-diamine, BQCN = N,N'-dimethyl-N,N'-bis(8-quinolyl)cyclohexanediamine, OTf = CF3SO3(-)) in a nonbuffered aqueous solution; turnover numbers of 80 ± 10 and 20 ± 5 were obtained in the O2 evolution reaction by 1 and 2, respectively. The ligand dissociation of the iron complexes was observed under acidic conditions, and the dissociated ligands were oxidized by CAN to yield CO2. We also observed that 1 was converted to an iron(IV)-oxo complex during the water oxidation in competition with the ligand oxidation. In addition, oxygen exchange between the iron(IV)-oxo complex and H2(18)O was found to occur at a much faster rate than the oxygen evolution. These results indicate that the iron complexes act as the true homogeneous catalyst for water oxidation by CAN at low pHs. In contrast, light-driven water oxidation using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and S2O8(2-) as a sacrificial electron acceptor was catalyzed by iron hydroxide nanoparticles derived from the iron complexes under basic conditions as the result of the ligand dissociation. In a buffer solution (initial pH 9.0) formation of the iron hydroxide nanoparticles with a size of around 100 nm at the end of the reaction was monitored by dynamic light scattering (DLS) in situ and characterized by X-ray photoelectron spectra (XPS) and transmission electron microscope (TEM) measurements. We thus conclude that the water oxidation by CAN was catalyzed by short-lived homogeneous iron complexes under acidic conditions, whereas iron hydroxide nanoparticles derived from iron complexes act as a heterogeneous catalyst in the light-driven water oxidation reaction under basic conditions.

Solubilization of polycyclic aromatic hydrocarbons in micellar nonionic surfactant solutions

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

Edwards, D.A.; Luthy, R.G.; Liu, Zhongbao

1991-01-01

Experimental data are presented on the enhanced apparent solubilities of naphthalene, phenanthrene, and pyrene resulting from solubilization in aqueous solutions of four commercial, nonionic surfactants: an alkyl polyoxyethylene (POE) type, two octylphenol POE types, and a nonylphenol POE type. Apparent solubilities of the polycyclic aromatic hydrocarbon (PAH) compounds in surfactant solutions were determined by radiolabeled techniques. Solubilization of each PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle form. The partitioning of organic compounds between surfactant micelles and aqueous solution is characterized by a mole fraction micelle-phase/aqueous-phase partition coefficient, K{submore » m}. Values of log K{sub m} for PAH compounds in surfactant solutions of this study range from 4.57 to 6.53. Log K{sub m} appears to be a linear function of log K{sub ow} for a given surfactant solution. A knowledge of partitioning in aqueous surfactant systems is a prerequisite to understanding mechanisms affecting the behavior of hydrophobic organic compounds in soil-water systems in which surfactants play a role in contaminant remediation or facilitated transport.« less

Raman spectra of amino acids and their aqueous solutions

NASA Astrophysics Data System (ADS)

Zhu, Guangyong; Zhu, Xian; Fan, Qi; Wan, Xueliang

2011-03-01

Amino acids are the basic "building blocks" that combine to form proteins and play an important physiological role in all life-forms. Amino acids can be used as models for the examination of the importance of intermolecular bonding in life processes. Raman spectra serve to obtain information regarding molecular conformation, giving valuable insights into the topology of more complex molecules (peptides and proteins). In this paper, amino acids and their aqueous solution have been studied by Raman spectroscopy. Comparisons of certain values for these frequencies in amino acids and their aqueous solutions are given. Spectra of solids when compared to those of the solute in solution are invariably much more complex and almost always sharper. We present a collection of Raman spectra of 18 kinds of amino acids ( L-alanine, L-arginine, L-aspartic acid, cystine, L-glutamic acid, L-glycine, L-histidine, L-isoluecine, L-leucine, L-lysine, L-phenylalanine, L-methionone, L-proline, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine) and their aqueous solutions that can serve as references for the interpretation of Raman spectra of proteins and biological materials.

STRIPPING OF URANIUM FROM ORGANIC EXTRACTANTS

DOEpatents

Crouse, D.J. Jr.

1962-09-01

A liquid-liquid extraction method is given for recovering uranium values from uranium-containing solutions. Uranium is removed from a uranium-containing organic solution by contacting said organic solution with an aqueous ammonium carbonate solution substantially saturated in uranium values. A uranium- containing precipitate is thereby formed which is separated from the organic and aqueous phases. Uranium values are recovered from this separated precipitate. (AE C)

PROCESS OF ELIMINATING HYDROGEN PEROXIDE IN SOLUTIONS CONTAINING PLUTONIUM VALUES

DOEpatents

Barrick, J.G.; Fries, B.A.

1960-09-27

A procedure is given for peroxide precipitation processes for separating and recovering plutonium values contained in an aqueous solution. When plutonium peroxide is precipitated from an aqueous solution, the supernatant contains appreciable quantities of plutonium and peroxide. It is desirable to process this solution further to recover plutonium contained therein, but the presence of the peroxide introduces difficulties; residual hydrogen peroxide contained in the supernatant solution is eliminated by adding a nitrite or a sulfite to this solution.

Process for the synthesis of iron powder

DOEpatents

Welbon, W.W.

1983-11-08

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder. 2 figs.

Piezoelectric Resonance Defined High Performance Sensors and Modulators

DTIC Science & Technology

2016-05-30

Lopez-Ribot, Amar S. Bhalla, Melissa Montes, Ruyan Guo. Properties of Silver and Copper Nanoparticle Containing Aqueous Suspensions and Evaluation of...Amar S. Bhalla, Ruyan Guo, “Properties of Silver and Copper Nanoparticle - Containing Aqueous Solutions and Their Anti-Biofilm Effects," (2015)Symposium...Properties of Silver and Copper Nanoparticle -Containing AqueousSolutions and Evaluation of their In Vitro Activity againstCandida albicans and

Kinetics of photobleaching of aqueous solutions of ricin agglutinin in the presence of guanidine chloride

NASA Astrophysics Data System (ADS)

Brandt, Nikolai N.; Chikishev, Andrey Y.

2002-05-01

Kinetics of background decay in Raman spectra of aqueous solutions of ricin agglutinin in the presence of guanidine chloride were measured. The differences in the kinetics of photobleaching are discussed.

Sorption of Ochratoxin A from Aqueous Solutions Using β-Cyclodextrin-Polyurethane Polymer

PubMed Central

Appell, Michael; Jackson, Michael A.

2012-01-01

The ability of a cyclodextrin-polyurethane polymer to remove ochratoxin A from aqueous solutions was examined by batch rebinding assays. The results from the aqueous binding studies were fit to two parameter models to gain insight into the interaction of ochratoxin A with the nanosponge material. The ochratoxin A sorption data fit well to the heterogeneous Freundlich isotherm model. The polymer was less effective at binding ochratoxin A in high pH buffer (9.5) under conditions where ochratoxin A exists predominantly in the dianionic state. Batch rebinding assays in red wine indicate the polymer is able to remove significant levels of ochratoxin A from spiked solutions between 1–10 μg·L−1. These results suggest cyclodextrin nanosponge materials are suitable to reduce levels of ochratoxin A from spiked aqueous solutions and red wine samples. PMID:22474569

Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-interactive Chemicals Contained in Boundary Layer-targeted Emulsions

NASA Technical Reports Server (NTRS)

Richmond, Robert Chafee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor)

2013-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, or water. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

NASA Technical Reports Server (NTRS)

Defalco, Francis G. (Inventor); Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor)

2017-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, water, or a water-based lubricant. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

NASA Technical Reports Server (NTRS)

Defalco, Francis G. (Inventor); Richmond, Robert Chaffee (Inventor); Schramm, Harry F., Jr. (Inventor)

2016-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, or water. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

Strengthening of the Coordination Shell by Counter Ions in Aqueous Th 4+ Solutions

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

Atta-Fynn, Raymond; Bylaska, Eric J.; de Jong, Wibe A.

The presence of counter ions in solutions containing highly charged metal cations can trigger processes such as ion-pair formation, hydrogen bond breakages and subsequent reformation, and ligand exchanges. In this work, it is shown how halide (Cl-, Br-) and perchlorate (ClO4-) anions affect the strength of the primary solvent coordination shells around Th4+ using explicit solvent and finite temperature ab initio molecular dynamics modeling methods. The 9-fold solvent geometry was found to be the most stable hydration structure in each aqueous solution. Relative to the dilute aqueous solution, the presence of the counter ions did not significantly alter the geometrymore » of the primary hydration shell. However, the free energy analyses indicated that the 10-fold hydrated states were thermodynamically accessible in dilute and bromide aqueous solutions within 1 kcal/mol. Analysis of the results showed that the hydrogen bond lifetimes were longer and solvent exchange energy barriers were larger in solutions with counter ions in comparison with the solution with no counter ions. This implies that the presence of the counter ions induces a strengthening of the Th4+ hydration shell.« less

Direct NMR Monitoring of Phase Separation Behavior of Highly Supersaturated Nifedipine Solution Stabilized with Hypromellose Derivatives.

PubMed

Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu

2017-07-03

We investigated the phase separation behavior and maintenance mechanism of the supersaturated state of poorly water-soluble nifedipine (NIF) in hypromellose (HPMC) derivative solutions. Highly supersaturated NIF formed NIF-rich nanodroplets through phase separation from aqueous solution containing HPMC derivative. Dissolvable NIF concentration in the bulk water phase was limited by the phase separation of NIF from the aqueous solution. HPMC derivatives stabilized the NIF-rich nanodroplets and maintained the NIF supersaturation with phase-separated NIF for several hours. The size of the NIF-rich phase was different depending on the HPMC derivatives dissolved in aqueous solution, although the droplet size had no correlation with the time for which NIF supersaturation was maintained without NIF crystallization. HPMC acetate and HPMC acetate succinate (HPMC-AS) effectively maintained the NIF supersaturation containing phase-separated NIF compared with HPMC. Furthermore, HPMC-AS stabilized NIF supersaturation more effectively in acidic conditions. Solution 1 H NMR measurements of NIF-supersaturated solution revealed that HPMC derivatives distributed into the NIF-rich phase during the phase separation of NIF from the aqueous solution. The hydrophobicity of HPMC derivative strongly affected its distribution into the NIF-rich phase. Moreover, the distribution of HPMC-AS into the NIF-rich phase was promoted at lower pH due to the lower aqueous solubility of HPMC-AS. The distribution of a large amount of HPMC derivatives into NIF-rich phase induced the strong inhibition of NIF crystallization from the NIF-rich phase. Polymer distribution into the drug-rich phase directly monitored by solution NMR technique can be a useful index for the stabilization efficiency of drug-supersaturated solution containing a drug-rich phase.

Rotational dynamics of trehalose in aqueous solutions studied by depolarized light scattering

NASA Astrophysics Data System (ADS)

Gallina, M. E.; Comez, L.; Morresi, A.; Paolantoni, M.; Perticaroli, S.; Sassi, P.; Fioretto, D.

2010-06-01

High resolution depolarized light scattering spectra, extended from 0.5 to 2×104 GHz by the combined used of a dispersive and an interferometric setup, give evidence of separated solute and solvent dynamics in diluted trehalose aqueous solutions. The slow relaxation process, located in the gigahertz frequency region, is analyzed as a function of temperature and concentration and assigned to the rotational diffusion of the sugar molecule. The results are discussed in comparison with the data obtained on glucose solutions and they are used to clarify the molecular origin of some among the several relaxation processes reported in literature for oligosaccharides solutions. The concentration dependence of relaxation time and of shear viscosity are also discussed, suggesting that the main effect of carbohydrate molecules on the structural relaxation of diluted aqueous solutions is the perturbation induced on the dynamics of the first hydration shell of each solute molecule.

Process for the combined removal of SO.sub.2 and NO.sub.x from flue gas

DOEpatents

Chang, Shih-Ger; Liu, David K.; Griffiths, Elizabeth A.; Littlejohn, David

1988-01-01

The present invention in one aspect relates to a process for the simultaneous removal of NO.sub.x and SO.sub.2 from a fluid stream comprising mixtures thereof and in another aspect relates to the separation, use and/or regeneration of various chemicals contaminated or spent in the process and which includes the steps of: (A) contacting the fluid stream at a temperature of between about 105.degree. and 180.degree. C. with a liquid aqueous slurry or solution comprising an effective amount of an iron chelate of an amino acid moiety having at least one --SH group; (B) separating the fluid stream from the particulates formed in step (A) comprising the chelate of the amino acid moiety and fly ash; (C) washing and separating the particulates of step (B) with an aqueous solution having a pH value of between about 5 to 8; (D) subsequently washing and separating the particulates of step (C) with a strongly acidic aqueous solution having a pH value of between about 1 to 3; (E) washing and separating the particulates of step (D) with an basic aqueous solution having a pH value of between about 9 to 12; (F) optionally adding additional amino acid moiety, iron (II) and alkali to the aqueous liquid from step (D) to produce an aqueous solution or slurry similar to that in step (A) having a pH value of between about 4 to 12; and (G) recycling the aqueous slurry of step (F) to the contacting zone of step (A). Steps (D) and (E) can be carried out in the reverse sequence, however the preferred order is (D) and then (E). In another preferred embodiment the present invention provides a process for the removal of NO.sub.x, SO.sub.2 and particulates from a fluid stream which includes the steps of (A) injecting into a reaction zone an aqueous solution itself comprising (i) an amino acid moiety selected from those described above; (ii) iron (II) ion; and (iii) an alkali, wherein the aqueous solution has a pH of between about 4 and 11; followed by solids separation and washing as is described in steps (B), (C), (D) and (E) above. The overall process is useful to reduce acid rain components from combustion gas sources.

Aptamer-based polyhedral oligomeric silsesquioxane (POSS)-containing hybrid affinity monolith prepared via a "one-pot" process for selective extraction of ochratoxin A.

PubMed

Chen, Yiqiong; Chen, Maolin; Chi, Jinxin; Yu, Xia; Chen, Yongxuan; Lin, Xucong; Xie, Zenghong

2018-08-17

A novel aptamer-based polyhedral oligomeric silsesquioxane (POSS)-containing hybrid affinity monolith has been prepared with a facile "one-pot" process simultaneously via "free radical polymerization" and "thiol-ene" click reaction, and used for on-line selective extraction and practical analysis to trace ochratoxin A (OTA). By using the ternary porogenic mixture composed of water/DMF/PEG, a homogeneous polymerization mixture with POSS chemicals, acrylate-based monomers and aptamer aqueous solution was obtained, and the copolymerization of POSS chemicals, polymer monomers and aptamer aqueous solution was systematically studied. Characterizations such as the morphology, FT-IR and fluorescence spectra, mechanical stability, dynamic binding capacity, cross-reactivity and selectivity of the resultant affinity monolith were also evaluated. Attributed to the porous monolithic structure and aptamer-based affinity interaction, acceptable selective recognition and recovery yields towards trace OTA were obtained. With a 5-fold volume enrichment, the limit of detection (LOD) and limit of quantitation (LOQ) of OTA in fortified beer samples were gained at 0.025 ng/mL (S/N = 3) and 0.045 ng/mL (S/N = 10), respectively. It could be competent for the sensitive measure of actual OTA residues in real beer samples. In comparison with the previously reported strategies containing common "sol-gel" chemistry, the proposed protocol to fabricating aptamer-modified POSS-containing hybrid affinity monolith showed a simpler preparation with acceptable selectivity and higher recovery to trace OTA. Copyright © 2018 Elsevier B.V. All rights reserved.