Vibrational mode frequencies of silica species in SiO2-H2O liquids and glasses from ab initio molecular dynamics.

PubMed

Spiekermann, Georg; Steele-MacInnis, Matthew; Schmidt, Christian; Jahn, Sandro

2012-04-21

Vibrational spectroscopy techniques are commonly used to probe the atomic-scale structure of silica species in aqueous solution and hydrous silica glasses. However, unequivocal assignment of individual spectroscopic features to specific vibrational modes is challenging. In this contribution, we establish a connection between experimentally observed vibrational bands and ab initio molecular dynamics (MD) of silica species in solution and in hydrous silica glass. Using the mode-projection approach, we decompose the vibrations of silica species into subspectra resulting from several fundamental structural subunits: The SiO(4) tetrahedron of symmetry T(d), the bridging oxygen (BO) Si-O-Si of symmetry C(2v), the geminal oxygen O-Si-O of symmetry C(2v), the individual Si-OH stretching, and the specific ethane-like symmetric stretching contribution of the H(6)Si(2)O(7) dimer. This allows us to study relevant vibrations of these subunits in any degree of polymerization, from the Q(0) monomer up to the fully polymerized Q(4) tetrahedra. Demonstrating the potential of this approach for supplementing the interpretation of experimental spectra, we compare the calculated frequencies to those extracted from experimental Raman spectra of hydrous silica glasses and silica species in aqueous solution. We discuss observed features such as the double-peaked contribution of the Q(2) tetrahedral symmetric stretch, the individual Si-OH stretching vibrations, the origin of the experimentally observed band at 970 cm(-1) and the ethane-like vibrational contribution of the H(6)Si(2)O(7) dimer at 870 cm(-1).

Changes in the IR Spectra of Aqueous Solutions of Alkali Metal Chlorides during Crystallization

NASA Astrophysics Data System (ADS)

Koroleva, A. V.; Matveev, V. K.; Koroleva, L. A.; Pentin, Yu. A.

2018-02-01

The IR spectra of aqueous solutions of sodium chloride and rubidium chloride with the same concentration of 0.1 M upon freezing are studied in the middle IR region. The changes that occur in the absorption bands of the bending ν2, compound ν2 + νL, and stretching (ν1, 2ν2, and ν3) vibrations of water molecules with gradual crystallization of the solutions are studied. The obtained spectra of crystallized solutions are compared to the IR spectrum of ice Ih. Analysis allows conclusions about the structure of the investigated frozen crystallized solutions.

Spectroscopic investigation on structure and pH dependent Cocrystal formation between gamma-aminobutyric acid and benzoic acid

NASA Astrophysics Data System (ADS)

Du, Yong; Xue, Jiadan; Cai, Qiang; Zhang, Qi

2018-02-01

Vibrational spectroscopic methods, including terahertz absorption and Raman scattering spectroscopy, were utilized for the characterization and analysis of gamma-aminobutyric acid (GABA), benzoic acid (BA), and the corresponding GABA-BA cocrystal formation under various pH values of aqueous solution. Vibrational spectroscopic results demonstrated that the solvent GABA-BA cocrystal, similar as grinding counterpart, possessed unique characteristic features compared with that of starting parent compounds. The change of vibrational modes for GABA-BA cocrystal comparing with starting components indicates there is strong inter-molecular interaction between GABA and BA molecules during its cocrystallization process. Formation of GABA-BA cocrystal under slow solvent evaporation is impacted by the pH value of aqueous solution. Vibrational spectra indicate that the GABA-BA cocrystal could be stably formed with the solvent condition of 2.00 ≤ pH ≤ 7.00. In contrast, such cocrystallization did not occur and the cocrystal would dissociate into its parent components when the pH value of solvent is lower than 2.00. This study provides experimental benchmark to discriminate and identify the structure of cocrystal and also pH-dependent cocrystallization effect with vibrational spectroscopic techniques in solid-state pharmaceutical fields.

Solvent effect on the vibrational spectra of Carvedilol.

PubMed

Billes, Ferenc; Pataki, Hajnalka; Unsalan, Ozan; Mikosch, Hans; Vajna, Balázs; Marosi, György

2012-09-01

Carvedilol (CRV) is an important medicament for heart arrhythmia. The aim of this work was the interpretation of its vibrational spectra with consideration on the solvent effect. Infrared and Raman spectra were recorded in solid state as well in solution. The experimental spectra were evaluated using DFT quantum chemical calculations computing the optimized structure, atomic net charges, vibrational frequencies and force constants. The same calculations were done for the molecule in DMSO and aqueous solutions applying the PCM method. The calculated force constants were scaled to the experimentally observed solid state frequencies. The characters of the vibrational modes were determined by their potential energy distributions. Solvent effects on the molecular properties were interpreted. Based on these results vibrational spectra were simulated. Copyright © 2012 Elsevier B.V. All rights reserved.

Vibrational studies in aqueous solutions. Part II. The acid oxalate ion and oxalic acid

NASA Astrophysics Data System (ADS)

Shippey, T. A.

1980-08-01

Assignments for oxalic acid in solution are re-examined. A detailed assignment of the IR and Raman spectra of the acid oxalate ion is presented for the first time. Raman spectroscopy is used to study the first ionization of oxalic acid.

Spectroscopic investigation on structure and pH dependent Cocrystal formation between gamma-aminobutyric acid and benzoic acid.

PubMed

Du, Yong; Xue, Jiadan; Cai, Qiang; Zhang, Qi

2018-02-15

Vibrational spectroscopic methods, including terahertz absorption and Raman scattering spectroscopy, were utilized for the characterization and analysis of gamma-aminobutyric acid (GABA), benzoic acid (BA), and the corresponding GABA-BA cocrystal formation under various pH values of aqueous solution. Vibrational spectroscopic results demonstrated that the solvent GABA-BA cocrystal, similar as grinding counterpart, possessed unique characteristic features compared with that of starting parent compounds. The change of vibrational modes for GABA-BA cocrystal comparing with starting components indicates there is strong inter-molecular interaction between GABA and BA molecules during its cocrystallization process. Formation of GABA-BA cocrystal under slow solvent evaporation is impacted by the pH value of aqueous solution. Vibrational spectra indicate that the GABA-BA cocrystal could be stably formed with the solvent condition of 2.00≤pH≤7.00. In contrast, such cocrystallization did not occur and the cocrystal would dissociate into its parent components when the pH value of solvent is lower than 2.00. This study provides experimental benchmark to discriminate and identify the structure of cocrystal and also pH-dependent cocrystallization effect with vibrational spectroscopic techniques in solid-state pharmaceutical fields. Copyright © 2017 Elsevier B.V. All rights reserved.

Electro-activation of potassium acetate, potassium citrate and calcium lactate: impact on solution acidity, Redox potential, vibrational properties of Raman spectra and antibacterial activity on E. coli O157:H7 at ambient temperature.

PubMed

Liato, Viacheslav; Labrie, Steve; Aïder, Mohammed

2016-01-01

To study the electro-activation of potassium acetate, potassium citrate and calcium lactate aqueous solutions and to evaluate their antimicrobial effect against E. coli O157:H7 at ambient temperature. Potassium acetate, potassium citrate and calcium lactate aqueous solutions were electrically excited in the anodic compartment of a four sectional electro-activation reactor. Different properties of the electro-activated solutions were measured such as: solutions acidity (pH and titratable), Redox potential and vibrational properties by Raman spectroscopy. Moreover, the antimicrobial activity of these solutions was evaluated against E. coli O157:H7. The results showed a pH decrease from 7.07 ± 0.08, 7.53 ± 0.12 and 6.18 ± 0.1 down to 2.82 ± 0.1, 2.13 ± 0.09 and 2.26 ± 0.15, after 180 min of electro-activation of potassium acetate, potassium citrate and calcium lactate solution, respectively. These solutions were characterized by high oxidative ORP of +1076 ± 12, +958 ± 11 and +820 ± 14 mV, respectively. Raman scattering analysis of anolytes showed stretching vibrations of the hydrogen bonds with the major changes within the region of 3410-3430 cm -1 . These solutions were used against E. coli O157:H7 and the results from antimicrobial assays showed high antibacterial effect with a population reduction of ≥6 log CFU/ml within 5 min of treatment. This study demonstrated the effectiveness of the electro-activation to confer to aqueous solutions of organic salts of highly reactive properties that differ them from their conjugated commercial acids. The electro-activated solutions demonstrated significant antimicrobial activity against E. coli O157:H7. This study opens new possibilities to use electro-activated solutions of salts of weak organic acids as food preservatives to develop safe, nutritive and low heat processed foods.

UV Resonance Raman Elucidation of the Terminal and Internal Peptide Bond Conformations of Crystalline and Solution Oligoglycines.

PubMed

Bykov, Sergei V; Asher, Sanford A

2010-11-30

Spectroscopic investigations of macromolecules generally attempt to interpret the measured spectra in terms of the summed contributions of the different molecular fragments. This is the basis of the local mode approximation in vibrational spectroscopy. In the case of resonance Raman spectroscopy independent contributions of molecular fragments require both a local mode-like behavior and the uncoupled electronic transitions. Here we show that the deep UV resonance Raman spectra of aqueous solution phase oligoglycines show independent peptide bond molecular fragment contributions indicating that peptide bonds electronic transitions and vibrational modes are uncoupled. We utilize this result to separately determine the conformational distributions of the internal and penultimate peptide bonds of oligoglycines. Our data indicate that in aqueous solution the oligoglycine terminal residues populate conformations similar to those found in crystals (3(1)-helices and β-strands), but with a broader distribution, while the internal peptide bond conformations are centered around the 3(1)-helix Ramachandran angles.

Environmental chemistry at vapor/water interfaces: insights from vibrational sum frequency generation spectroscopy.

PubMed

Jubb, Aaron M; Hua, Wei; Allen, Heather C

2012-01-01

The chemistry that occurs at surfaces has been an intense area of study for many years owing to its complexity and importance in describing a wide range of physical phenomena. The vapor/water interface is particularly interesting from an environmental chemistry perspective as this surface plays host to a wide range of chemistries that influence atmospheric and geochemical interactions. The application of vibrational sum frequency generation (VSFG), an inherently surface-specific, even-order nonlinear optical spectroscopy, enables the direct interrogation of various vapor/aqueous interfaces to elucidate the behavior and reaction of chemical species within the surface regime. In this review we discuss the application of VSFG to the study of a variety of atmospherically important systems at the vapor/aqueous interface. Chemical systems presented include inorganic ionic solutions prevalent in aqueous marine aerosols, small molecular solutes, and long-chain fatty acids relevant to fat-coated aerosols. The ability of VSFG to probe both the organization and reactions that may occur for these systems is highlighted. A future perspective toward the application of VSFG to the study of environmental interfaces is also provided.

Structure of thallium(III) chloride, bromide, and cyanide complexes in aqueous solution

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

Blixt, J.; Glaser, J.; Sandstroem, M.

1995-05-10

The structures of the hydrated thallium(III) halide and pseudohalide complexes, [TlX{sub n}(OH{sub 2}){sub m}]{sup (3-d)+}, X = Cl, Br, CN, in aqueous solution have been studied by a combination of X-ray absorption fine structure spectroscopy (XAFS), large-angle X-ray scattering (LAXS), and vibrational spectroscopic (Raman and IR) techniques including far-infrared studies of aqueous solutions and some solid phases with known structures. The vibrational Tl-X frequencies of all complexes are reported, force constants are calculated using normal coordinate analysis, and assignments are given. The structural results are consistent with octahedral six-coordination for the cationic complexes Tl(OH{sub 2}){sub 6}{sup 3$PLU}, TlX(OH{sub 2}){sub 5}{supmore » 2+}, and trans-TlX{sub 2}(OH{sub 2}){sub 4}{sup +}. The coordination geometry changes to trigonal bipyramidal for the neutral TlBr{sub 3}(OH{sub 2}){sub 2} complex and possibly also for TlCl{sub 3}(OH{sub 2}){sub 2}. The TlX{sub 4}{sup -} complexes are all tetrahedral. Higher chloride complexes, TlCl{sub 5}(OH{sub 2}){sup 2-} and TlCl{sub 6}{sup 3-}, are formed and have again octahedral coordination geometry. 65 refs., 7 figs., 5 tabs.« less

Removal of Cu(II) metal ions from aqueous solution by amine functionalized magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Kothavale, V. P.; Karade, V. C.; Waifalkar, P. P.; Sahoo, Subasa C.; Patil, P. S.; Patil, P. B.

2018-04-01

The adsorption behavior of Cu(II) metal cations was investigated on the amine functionalized magnetic nanoparticles (MNPs). TheMNPs were synthesized by thesolvothermal method and functionalized with (3-Aminopropyl)triethoxysilane (APTES). MNPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM). The MNPs have pure magnetite phase with particle size around 10-12 nm. MNPs exhibits superparamagnetic behavior with asaturation magnetization of 68 emu/g. The maximum 38 % removal efficiency was obtained for Cu(II) metal ions from the aqueous solution.

Identification of Multiple Water-Iodide Species in Concentrated NaI Solutions Based on the Raman Bending Vibration of Water.

PubMed

Besemer, Matthieu; Bloemenkamp, Rob; Ariese, Freek; van Manen, Henk-Jan

2016-02-11

The influence of aqueous electrolytes on the water bending vibration was studied with Raman spectroscopy. For all salts investigated (NaI, NaBr, NaCl, and NaSCN), we observed a nonlinear intensity increase of the water bending vibration with increasing concentration. Different lasers and a tunable frequency-doubled optical parametric oscillator system were used to achieve excitation wavelengths between 785 and 374 nm. Focusing on NaI solutions, the relative enhancement of the water bending vibration was found to increase strongly with excitation photon energy, in line with a preresonance effect from the iodide-water charge-transfer transition. We used multivariate curve resolution (MCR) to decompose the measured Raman spectra of NaI solutions into three interconverting spectral components assigned to bulk water and water molecules interacting with one (X···H-O-H···O) and two (X···H-O-H···X) iodide ions (X = I(-)). The Raman spectrum of solid sodium iodide dihydrate supports the assignment of the latter. Using the MCR results, relative Raman scattering cross sections of 4.0 ± 0.6 and 14.0 ± 0.1 were calculated for the mono- and di-iodide species, respectively (compared to that of bulk water set to unity). In addition, it was found that at relatively low concentrations each iodide ion affects the Raman spectrum of roughly 22 surrounding water molecules, indicating that the influence of iodide extends beyond the first solvation shell. Our results demonstrate that the Raman bending vibration of water is a sensitive probe, providing new insights into anion solvation in aqueous environments.

Synergistic Effect of Polypyrrole-Intercalated Graphene for Enhanced Corrosion Protection of Aqueous Coating in 3.5% NaCl Solution.

PubMed

Qiu, Shihui; Li, Wei; Zheng, Wenru; Zhao, Haichao; Wang, Liping

2017-10-04

Dispersion of graphene in water and its incorporation into waterborne resin have been rarely researched and hardly achieved owing to its hydrophobicity. Furthermore, it has largely been reported that graphene with impermeability contributed to the improved anticorrosion property. Here, we show that highly concentrated graphene aqueous solution up to 5 mg/mL can be obtained by synthesizing hydrophilic polypyrrole (PPy) nanocolloids as intercalators and ultrasonic vibration. On the basis of π-π interaction between PPy and graphene, stacked graphene sheets are exfoliated to the thickness of three to five layers without increasing defects. The corrosion performance of coatings without and with PPy and graphene is obtained by potential and impedance measurements, Tafel curves, and fitted pore resistance by immersing in a 3.5 wt % NaCl solution. It turns out that composite coating with 0.5 wt % graphene additive exhibits superior anticorrosive ability. The mechanism of intercalated graphene-based coating is interpreted as the synergistic protection of impermeable graphene sheets and self-healing PPy and proved by the identification of corrosion products and the scanning vibrating electrode technique.

pH titration monitored by quantum cascade laser-based vibrational circular dichroism.

PubMed

Rüther, Anja; Pfeifer, Marcel; Lórenz-Fonfría, Víctor A; Lüdeke, Steffen

2014-04-10

Vibrational circular dichroism (VCD) spectra of aqueous solutions of proline were recorded in the course of titrations from basic to acidic pH using a spectrometer equipped with a quantum cascade laser (QCL) as an infrared light source in the spectral range from 1320 to 1220 cm(-1). The pH-dependent spectra were analyzed by singular value decomposition and global fitting of a two-pK Henderson-Hasselbalch model. The analysis delivered relative fractions of the three different protonation species. Their agreement with the relative fractions obtained from performing the same analysis on pH-dependent Fourier transform infrared (FT-IR) and QCL-IR spectra validates the quantitative results from QCL-VCD. Global fitting of the pH-dependent VCD spectra of L-proline allowed for extraction of pure spectra corresponding to anionic, zwitterionic, and cationic L-proline. From a static experiment, only pure spectra of the zwitterion would be accessible in a straightforward way. A comparison to VCD spectra calculated for all three species led to assignment of vibrational modes that are characteristic for the respective protonation states. The study demonstrates the applicability of QCL-VCD both for quantitative evaluation and for qualitative interpretation of dynamic processes in aqueous solutions.

Synthesis and Characterization of Mixed Iron-Manganese Oxide Nanoparticles and Their Application for Efficient Nickel Ion Removal from Aqueous Samples

PubMed Central

Serra, Antonio; Monteduro, Anna Grazia; Padmanabhan, Sanosh Kunjalukkal; Licciulli, Antonio; Bonfrate, Valentina; Salvatore, Luca; Calcagnile, Lucio

2017-01-01

Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution. PMID:28804670

Removal of selected pharmaceuticals from aqueous solution using magnetic chitosan: sorption behavior and mechanism.

PubMed

Zhang, Yalei; Shen, Zhe; Dai, Chaomeng; Zhou, Xuefei

2014-11-01

A novel-modified magnetic chitosan adsorbent was used to remove selected pharmaceuticals, i.e., diclofenac (DCF) and clofibric acid (CA) and carbamazepine (CBZ), from aqueous solutions. The characterization of magnetic chitosan was achieved by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and nitrogen sorption analysis. The magnetic chitosan had effective sorption affinity for DCF and CA but no sorption of CBZ was observed. The sorption capacities of CA and DCF in the individual solutions were 191.2 and 57.5 mg/g, respectively. While in mixed solution, DCF showed higher sorption affinity. Sorption kinetics indicated a quick equilibrium reached within 2 min. Lower solution pH values were found to be advantageous for the adsorption process. The sorption efficacy of CA declined significantly with increasing inorganic salt concentration. However, sorption performance of DCF was stable under different ionic strength conditions.

Vibrational Raman optical activity of ketose monosaccharides

NASA Astrophysics Data System (ADS)

Bell, Alasdair F.; Hecht, Lutz; Barron, Laurence D.

1995-07-01

The vibrational Raman optical activity (ROA) spectra of the four ketose sugars D-fructose, L-sorbose, D-tagatose and D-psicose in aqueous solution, which have been measured in backscattering in the range ≈250-1500 cm -1, are reported. These results are combined with those from a previous ROA study of aldose and pentose sugars in an attempt to establish new vibrational assignments and to verify old ones. The high information content of these spectra provides a new perspective on all the central features of monosaccharide stereochemistry including dominant anomeric configuration, ring conformation, exocyclic CH 2OH group conformation and relative disposition of the hydroxyl groups around the ring.

Dual Approach to Vibrational Spectra in Solution: Microscopic Influence of Hydrogen Bonding to the State of Motion of Glycine in Water.

PubMed

Kitamura, Yukichi; Takenaka, Norio; Koyano, Yoshiyuki; Nagaoka, Masataka

2014-08-12

We have proposed a new theoretical methodology to clarify the microscopic nature of the vibrational properties in solution, which consists of a combination of the vibrational frequency analyses (VFAs) with two kinds of Hessian matrices, that is, the effective Hessian on the free energy surface (free energy Hessian: "FE-Hessian") and the instantaneous one (instantaneous normal mode Hessian: "INM-Hessian") within QM/MM framework. In these VFAs, the Hessians were obtained by the analytical approach, having the advantages from the aspect of both the computational efficiency and accuracy in comparison to those obtained by the numerical one. In the present study, we have applied them to the glycine aqueous solution. First, by using the VFA with the FE-Hessian (VFA-FEH), we estimated the vibrational frequency shifts induced by solvent water molecules. The calculated values were quantitatively in agreement with experimental ones. It was clearly demonstrated that such vibrational shifts are attributed to not only the structural relaxation but also the explicit solute-solvent interactions (i.e., interatomic interactions). Second, by using the VFA with the INM-Hessian (VFA-INMH), the vibrational spectra in solution were investigated through the vibrational INM densities of states (DOS). By the comparison between the spectroscopic features and the microscopic solvation structure around glycine molecule, it was found that the frequency shifts and bandwidths in IR spectra are closely correlated with the hydrogen bonding (HB) network formations. In particular, the instantaneous changes of vibrational states of the hydroxyl group and carbonyl one, showing apparently inverse tendency on the strength of the HB interaction, can be explained very well on the basis of two different mechanisms, that is, the direct change of electron density in the bonding orbitals and the indirect one due to hyperconjugation between the lone electron pair and the antibonding orbitals, respectively. In conclusion, the present dual VFA approach is a quite useful strategy to interpret the microscopic origin of the experimental vibrational spectra.

The Clusters-in-a-Liquid Approach for Solvation: New Insights from the Conformer Specific Gas Phase Spectroscopy and Vibrational Optical Activity Spectroscopy

PubMed Central

Perera, Angelo S.; Thomas, Javix; Poopari, Mohammad R.; Xu, Yunjie

2016-01-01

Vibrational optical activity spectroscopies, namely vibrational circular dichroism (VCD) and Raman optical activity (ROA), have been emerged in the past decade as powerful spectroscopic tools for stereochemical information of a wide range of chiral compounds in solution directly. More recently, their applications in unveiling solvent effects, especially those associated with water solvent, have been explored. In this review article, we first select a few examples to demonstrate the unique sensitivity of VCD spectral signatures to both bulk solvent effects and explicit hydrogen-bonding interactions in solution. Second, we discuss the induced solvent chirality, or chiral transfer, VCD spectral features observed in the water bending band region in detail. From these chirality transfer spectral data, the related conformer specific gas phase spectroscopic studies of small chiral hydration clusters, and the associated matrix isolation VCD experiments of hydrogen-bonded complexes in cold rare gas matrices, a general picture of solvation in aqueous solution emerges. In such an aqueous solution, some small chiral hydration clusters, rather than the chiral solutes themselves, are the dominant species and are the ones that contribute mainly to the experimentally observed VCD features. We then review a series of VCD studies of amino acids and their derivatives in aqueous solution under different pHs to emphasize the importance of the inclusion of the bulk solvent effects. These experimental data and the associated theoretical analyses are the foundation for the proposed “clusters-in-a-liquid” approach to account for solvent effects effectively. We present several approaches to identify and build such representative chiral hydration clusters. Recent studies which applied molecular dynamics simulations and the subsequent snapshot averaging approach to generate the ROA, VCD, electronic CD, and optical rotatory dispersion spectra are also reviewed. Challenges associated with the molecular dynamics snapshot approach are discussed and the successes of the seemingly random “ad hoc explicit solvation” reported before are also explained. To further test and improve the “clusters-in-a-liquid” model in practice, future work in terms of conformer specific gas phase spectroscopy of sequential solvation of a chiral solute, matrix isolation VCD measurements of small chiral hydration clusters, and more sophisticated models for the bulk solvent effects would be highly valuable. PMID:26942177

Synthesis of 1,3-Dimethylimidazolium Chloride and Volumetric Property Investigations of Its Aqueous Solution

NASA Astrophysics Data System (ADS)

Dong, L.; Zheng, D. X.; Wei, Z.; Wu, X. H.

2009-10-01

By investigating the vapor pressure of the solvent and the affinity between ionic liquids (ILs) and the solvent, it is proposed that 1,3-dimethylimidazolium chloride ([Mmim]Cl) has the potential to be used as a novel absorbent species with the absorption cycle working fluid. Adopting a high-pressure reaction kettle, the method of gas-liquid phase reaction was used to synthesize [Mmim]Cl under the conditions of 348.15 K and 0.7 MPa. The densities of [Mmim]Cl aqueous solutions were measured for mass fractions in the range from 20% to 90% at 293.15 K, 298.15 K, 303.15 K, 308.15 K, 313.15 K, and 318.15 K with a digital vibrating-tube densimeter. The excess volume, the apparent molar volume, the partial molar volume, and the apparent molar expansibility of this system were investigated, and the influences of variations of the cation and anion on the density of several IL aqueous solutions are discussed.

Mechanism of vibrational energy dissipation of free OH groups at the air-water interface.

PubMed

Hsieh, Cho-Shuen; Campen, R Kramer; Okuno, Masanari; Backus, Ellen H G; Nagata, Yuki; Bonn, Mischa

2013-11-19

Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air-water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air-H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces.

Mechanism of vibrational energy dissipation of free OH groups at the air–water interface

PubMed Central

Hsieh, Cho-Shuen; Campen, R. Kramer; Okuno, Masanari; Backus, Ellen H. G.; Nagata, Yuki; Bonn, Mischa

2013-01-01

Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air–water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air–H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces. PMID:24191016

Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine—Its vibrational spectra and theoretical calculations

NASA Astrophysics Data System (ADS)

Marchewka, M. K.; Drozd, M.; Janczak, J.

2011-08-01

The N-(4-nitrophenyl)-β-alanine in crystalline form directly by the addition of 4-nitroaniline to the acrylic acid in aqueous solution has been obtained. The title β-alanine derivative crystallizes in the P2 1/ c space group of monoclinic system with four molecules per unit cell. The X-ray geometry of β-alanine derivative molecule has been compared with those obtained by molecular orbital calculations corresponding to the gas phase. In the crystal the molecules related by an inversion center interact via symmetrically equivalent O-H⋯O hydrogen bonds with O⋯O distance of 2.656(2) Å forming a dimeric structure. The dimers of β-alanine derivative weakly interact via N-H⋯O hydrogen bonds between the H atom of β-amine groups and one of O atom of nitro groups. The room temperature powder vibrational (infrared and Raman) measurements are in accordance with the X-ray analysis. In aqueous solution of 4-nitroaniline and acrylic acid, the double C dbnd C bond of vinyl group of acrylic acid breaks as result of 4-nitroaniline addition.

Study of L-ascorbic acid (vitamin C)/H 2O mixture across glass transition

NASA Astrophysics Data System (ADS)

Migliardo, F.; Branca, C.; Faraone, A.; Magazù, S.; Migliardo, P.

2001-07-01

In this paper, we report quasi elastic neutron scattering (QENS) spectra of vitamin C aqueous solutions, obtained using MIBEMOL spectrometer (LLB). The main purpose of this work is to characterize the relaxational and vibrational properties of the Vitamin C/H 2O system below and above the glass transition temperature by analysing the low-frequency neutron scattering spectra. The determination of the relative weight of vibrational over relaxational contributions allows to get information on the fragility degree of this peculiar hydrogen-bond system.

Mechanically triggered solute uptake in soft contact lenses.

PubMed

Tavazzi, Silvia; Ferraro, Lorenzo; Fagnola, Matteo; Cozza, Federica; Farris, Stefano; Bonetti, Simone; Simonutti, Roberto; Borghesi, Alessandro

2015-06-01

Molecular arrangement plays a role in the diffusion of water and solutes across soft contact lenses. In particular, the uptake of solutes in hydrated contact lenses can occur as long as free water is available for diffusion. In this work, we investigated the effect of mechanical vibrations of low frequency (200 Hz) on the solute uptake. Hyaluronan, a polysaccharide of ophthalmic use, was taken as example of solute of interest. For a specific water-hydrated hydrogel material, differential scanning calorimetry experiments showed that a large fraction of the hydration water accounted for loosely-bound water, both before and after one week of daily-wear of the lenses. The size (of the order of magnitude of few hundreds of nanometers) of hyaluronan in aqueous solution was found to be less than the size of the pores of the lens observed by scanning electron microscopy. However, solute uptake in already-hydrated lenses was negligible by simple immersion, while a significant increase occurred under mechanical vibrations of 200 Hz, thus providing experimental evidence of mechanically triggered enhanced solute uptake, which is attributed to the release of interfacial loosely-bound water. Also other materials were taken into consideration. However, the effectiveness of mechanical vibrations for hyaluronan uptake is restricted to lenses containing interfacial loosely-bound water. Indeed, loosely-bound water is expected to be bound to the polymer with bonding energies of the order of magnitude of 10-100 J/g, which are compatible with the energy input supplied by the vibrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Theoretical and vibrational study of N-(3-chloro-4-fluoro-phenyl)-7-methoxy-6-(3-morpholin-4-ylpropoxy)-quinazolin-4-amine (gefitinib)

NASA Astrophysics Data System (ADS)

Mıhçıokur, Özlem; Özpozan, Talat

2015-12-01

N-(3-chloro-4fluoro-phenyl)-7-methoxy-6-(3-morpholin-4ylpropoxy)-quinazolin-4-amine (GEF), a quinalizoline derivative used as new anti-cancer agent, designed to target activity of epidermal growth factor receptor (EGFR) promoting the growth, division and spread of cancer cells, was examined from the vibrational and theoretical point of view. All calculations have been carried out both in gaseous and aqueous phases. In the calculations of both phases, the molecule has been optimized through conformer analysis beginning with the x-ray data. The conformer analyses have been carried out in each phases and the geometrical differences between the most stable structures in gaseous and in aqueous phases have been discussed. The solvent effect for GEF in aqueous solution was simulated by using self-consistent reaction field (SCRF) calculations employing the integral equation formalism variant (IEFPCM) model. NBO analysis has been performed to indicate the presence of intramolecular charge transfer. The complete assignments of the vibrational spectra (IR&Raman) were made with the aid of calculated spectra both in gaseous and aqueous phases. The observed spectral data of the title compound were compared with the calculated spectra obtained by DFT/B3LYP and DFT/B3PW91 methods using 6-31G(d,p) basis set. The theoretical results were found to be in good agreement with the measured experimental data especially for the interpretation of intra molecular interactions.

Towards ultrasound enhanced mid-IR spectroscopy for sensing bacteria in aqueous solutions

NASA Astrophysics Data System (ADS)

Freitag, Stephan; Schwaighofer, Andreas; Radel, Stefan; Lendl, Bernhard

2018-02-01

We employ attenuated total reflection (ATR) mid-IR technology for sensing of bacteria present in aqueous solution. In ATR spectroscopy, the penetration depth of the evanescent field extends to approx. 1-2 micrometers into the aqueous solution depending on the refractive index of the employed materials (Si, ZnS, Ge) used as attenuated total reflection (ATR) element and the geometry of the optical set-up. Due to the flow profile in the microfluidic cell, an additional force is required to bring particles into the evanescent field for measurement. For that purpose, we employ standing ultrasound waves produced between a sound source vibrating at approx. 2 MHz and the ATR crystal acting as a reflector. This ultrasonic trap is integrated into the microfluidic channel. As aqueous solution is passing through that acoustofluidic cell, particles are concentrated in the nodal plane of the standing ultrasound wave, forming particle conglomerates. By selecting appropriate experimental conditions, it is then possible to press bacteria against the crystal surface for interaction with the evanescent wave (as well as to keep them away from the ATR element). Our current work aims at establishing a custommade US-ATR-IR setup for signal enhancement of bacteria (e.g. E. coli, P. aeruginosa as well as Salmonella) in drinking water.

Why is hydrofluoric acid a weak acid?

PubMed

Ayotte, Patrick; Hébert, Martin; Marchand, Patrick

2005-11-08

The infrared vibrational spectra of amorphous solid water thin films doped with HF at 40 K reveal a strong continuous absorbance in the 1000-3275 cm(-1) range. This so-called Zundel continuum is the spectroscopic hallmark for aqueous protons. The extensive ionic dissociation of HF at such low temperature suggests that the reaction enthalpy remains negative down to 40 K. These observations support the interpretation that dilute HF aqueous solutions behave as weak acids largely due to the large positive reaction entropy resulting from the structure making character of the hydrated fluoride ion.

Probing water dynamics with OH -

NASA Astrophysics Data System (ADS)

Corridoni, T.; Sodo, A.; Bruni, F.; Ricci, M. A.; Nardone, M.

2007-07-01

Isotropic Raman spectra of aqueous solutions of LiOH, NaOH and KOH at concentrations ranging from high dilution to saturation have been measured and the frequency and width of the OH - stretching band have been analyzed. The dependence of the bandwidth on solute concentration suggests that the OH - vibration undergoes a transition from fast to slow modulation regimes as the solvent concentration decreases below the value of ˜20 water molecules per solute molecule. A correlation between this finding and structural modifications of the H-bond network of the solvent at similar concentrations is envisaged.

Determining the Structure of Oxalate Anion Using Infrared and Raman Spectroscopy Coupled with Gaussian Calculations

ERIC Educational Resources Information Center

Peterson, Karen I.; Pullman, David P.

2016-01-01

A laboratory project for the upper-division physical chemistry laboratory is described, and it combines IR and Raman spectroscopies with Gaussian electronic structure calculations to determine the structure of the oxalate anion in solid alkali oxalates and in aqueous solution. The oxalate anion has two limiting structures whose vibrational spectra…

Study on Colloid Vibration Current in Aqueous Solution of Binary Surfactant Mixtures: Effects of Counterions and Hydrophobic Chains.

PubMed

Takata, Youichi; Hyono, Atsushi; Ohshima, Hiroyuki

2016-11-01

In order to elucidate an electroacoustic phenomenon of mixed micelles in an aqueous solution, we measured the colloid vibration current (CVI) in aqueous solutions of binary surfactant mixtures. Based on the thermodynamic treatment of critical micelle concentration (cmc) values determined by conductivity measurements, it was expected that dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium chloride (DTAC) molecules would mix ideally in the micelle. However, the micelle composition as evaluated from the CVI measurement, based on the linear dependence of the CVI value on the micelle composition, differed from the aforementioned ideality. Considering these observations, we concluded that the CVI measurement was more sensitive to the counterion distribution near the micelle surface, whereas the thermodynamically determined micelle composition included the counterions more loosely bound in the diffuse double layer due to the electroneutrality condition included in its assumption. On the other hand, the phase diagram illustrating micelle formation in the lithium dodecyl sulfate (LiDS) - lithium perfluorooctane sulfonate (LiFOS) mixture system showed a heteroazeotropic point arising from the stronger interactions between homologous surfactants than between heterologous ones. Although the concentration dependence of CVI values was expected to drastically change at a heteroazeotropic point due to the enormous variation in the density of the micelle core, the results showed a monotonous change, which suggests that the density of the micelle core varies continuously. By taking the partial molar volume of fluorocarbon compounds in the hydrocarbon compounds into account, the density of the micelle core was affected by the size of the micelle as well as its constituents.

Structural characterization of environmentally relevant ternary uranyl citrate complexes present in aqueous solutions and solid state materials.

PubMed

Basile, Madeline; Unruh, Daniel K; Flores, Erin; Johns, Adam; Forbes, Tori Z

2015-02-14

Organic acids are important metal chelators in environmental systems and tend to form soluble complexes in aqueous solutions, ultimately influencing the transport and bioavailability of contaminants in surface and subsurface waters. This is particularly true for the formation of uranyl citrate complexes, which have been utilized in advanced photo- and bioremediation strategies for soils contaminated with nuclear materials. Given the complexity of environmental systems, the formation of ternary or heterometallic uranyl species in aqueous solutions are also expected, particularly with Al(iii) and Fe(iii) cations. These ternary forms are reported to be more stable in aqueous solutions, potentially enhancing contaminant mobility and uptake by organisms, but the exact coordination geometries of these soluble molecular complexes have not been elucidated. To provide insight into the nature of these species, we have developed a series of geochemical model compounds ([(UO(2))(2)Al(2)(C(6)H(4)O(7))(4)](6-) (U(2)Al(2)), [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)](6-) (U(2)Fe(2)-1) and [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)(H(2)O)(2)](6-) (U(2)Fe(2)-2) and [(UO(2))(2)Fe(4)(OH)(4)(C(6)H(4)O(7))(4)](8-) (U(2)Fe(4))) that were characterized by single-crystal X-ray diffraction and vibrational spectroscopy. Mass spectroscopy was then employed to compare the model compounds to species present in aqueous solutions to provide an enhanced understanding of the ternary uranyl citrate complexes that could be relevant in natural systems.

Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl2 solution interfaces

NASA Astrophysics Data System (ADS)

Ishiyama, Tatsuya; Shirai, Shinnosuke; Okumura, Tomoaki; Morita, Akihiro

2018-06-01

Molecular dynamics (MD) simulations of KCl, NaCl, and CaCl2 solution/dipalmytoylphosphatidylcholine lipid interfaces were performed to analyze heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectra in relation to the interfacial water structure. The present MD simulation well reproduces the experimental spectra and elucidates a specific cation effect on the interfacial structure. The K+, Na+, and Ca2+ cation species penetrate in the lipid layer more than the anions in this order, due to the electrostatic interaction with negative polar groups of lipid, and the electric double layer between the cations and anions cancels the intrinsic orientation of water at the water/lipid interface. These mechanisms explain the HD-VSFG spectrum of the water/lipid interface and its spectral perturbation by adding the ions. The lipid monolayer reverses the order of surface preference of the cations at the solution/lipid interface from that at the solution/air interface.

Exploring Nuclear Photorelaxation of Pyranine in Aqueous Solution: an Integrated Ab-Initio Molecular Dynamics and Time Resolved Vibrational Analysis Approach.

PubMed

Chiariello, Maria Gabriella; Rega, Nadia

2018-03-22

Advances in time-resolved vibrational spectroscopy techniques provided a new stimulus for understanding the transient molecular dynamics triggered by the electronic excitation. The detailed interpretation of such time-dependent spectroscopic signals is a challenging task from both experimental and theoretical points of view. We simulated and analyzed the transient photorelaxation of the pyranine photoacid in aqueous solution, with special focus on structural parameters and low frequency skeleton modes that are possibly preparatory for the photoreaction occurring at later time, as suggested by experimental spectroscopic studies. To this aim, we adopted an accurate computational protocol that combines excited state ab initio molecular dynamics within an hybrid quantum mechanical/molecular mechanics framework and a time-resolved vibrational analysis based on the Wavelet transform. According to our results, the main nuclear relaxation on the excited potential energy surface is completed in about 500 fs, in agreement with experimental data. The rearrangement of C-C bonds occurs according to a complex vibrational dynamics, showing oscillatory patterns that are out of phase and modulated by modes below 200 cm -1 . We also analyzed in both the ground and the excited state the evolution of some structural parameters involved in excited state proton transfer reaction, namely, those involving the pyranine and the water molecule hydrogen bonded to the phenolic O-H group. Both the hydrogen bond distance and the intermolecular orientation are optimized in the excited state, resulting in a tighter proton donor-acceptor couple. Indeed, we found evidence that collective low frequency skeleton modes, such as the out of plane wagging at 108 cm -1 and the deformation at 280 cm -1 , are photoactivated by the ultrafast part of the relaxation and modulate the pyranine-water molecule rearrangement, favoring the preparatory step for the photoreactivity.

Resonance tunneling electron-vibrational spectroscopy of polyoxometalates.

PubMed

Dalidchik, F I; Kovalevskii, S A; Balashov, E M

2017-05-21

The tunneling spectra of the ordered monolayer films of decamolybdodicobaltate (DMDC) compounds deposited from aqueous solutions on HOPG were measured by scanning tunnel microscopy in air. The DMDC spectra, as well as the tunneling spectra of other polyoxometalates (POMs), exhibit well-defined negative differential resistances (NDRs). The mechanism of formation of these spectral features was established from the collection of revealed NDR dependences on the external varying parameters and found to be common to all systems exhibiting Wannier-Stark localization. A model of biresonance tunneling was developed to provide an explanation for the totality of experimental data, both the literature and original, on the tunneling POM probing. A variant of the tunneling electron-vibrational POM spectroscopy was proposed allowing the determination of the three basic energy parameters-energy gaps between the occupied and unoccupied states, frequencies of the vibrational transitions accompanying biresonance electron-tunneling processes, and electron-vibrational interaction constants on the monomolecular level.

Resonance tunneling electron-vibrational spectroscopy of polyoxometalates

PubMed Central

Dalidchik, F. I.; Kovalevskii, S. A.

2017-01-01

The tunneling spectra of the ordered monolayer films of decamolybdodicobaltate (DMDC) compounds deposited from aqueous solutions on HOPG were measured by scanning tunnel microscopy in air. The DMDC spectra, as well as the tunneling spectra of other polyoxometalates (POMs), exhibit well-defined negative differential resistances (NDRs). The mechanism of formation of these spectral features was established from the collection of revealed NDR dependences on the external varying parameters and found to be common to all systems exhibiting Wannier–Stark localization. A model of biresonance tunneling was developed to provide an explanation for the totality of experimental data, both the literature and original, on the tunneling POM probing. A variant of the tunneling electron-vibrational POM spectroscopy was proposed allowing the determination of the three basic energy parameters—energy gaps between the occupied and unoccupied states, frequencies of the vibrational transitions accompanying biresonance electron-tunneling processes, and electron-vibrational interaction constants on the monomolecular level. PMID:28527451

Water-separated ion pairs cause the slow dielectric mode of magnesium sulfate solutions

NASA Astrophysics Data System (ADS)

Mamatkulov, Shavkat I.; Rinne, Klaus F.; Buchner, Richard; Netz, Roland R.; Bonthuis, Douwe Jan

2018-06-01

We compare the dielectric spectra of aqueous MgSO4 and Na2SO4 solutions calculated from classical molecular dynamics simulations with experimental data, using an optimized thermodynamically consistent sulfate force field. Both the concentration-dependent shift of the static dielectric constant and the spectral shape match the experimental results very well for Na2SO4 solutions. For MgSO4 solutions, the simulations qualitatively reproduce the experimental observation of a slow mode, the origin of which we trace back to the ion-pair relaxation contribution via spectral decomposition. The radial distribution functions show that Mg2+ and SO42 - ions form extensive water-separated—and thus strongly dipolar—ion pairs, the orientational relaxation of which provides a simple physical explanation for the prominent slow dielectric mode in MgSO4 solutions. Remarkably, the Mg2+-SO42 - ion-pair relaxation extends all the way into the THz range, which we rationalize by the vibrational relaxation of tightly bound water-separated ion pairs. Thus, the relaxation of divalent ion pairs can give rise to widely separated orientational and vibrational spectroscopic features.

Unified molecular picture of the surfaces of aqueous acid, base, and salt solutions.

PubMed

Mucha, Martin; Frigato, Tomaso; Levering, Lori M; Allen, Heather C; Tobias, Douglas J; Dang, Liem X; Jungwirth, Pavel

2005-04-28

The molecular structure of the interfacial regions of aqueous electrolytes is poorly understood, despite its crucial importance in many biological, technological, and atmospheric processes. A long-term controversy pertains between the standard picture of an ion-free surface layer and the strongly ion specific behavior indicating in many cases significant propensities of simple inorganic ions for the interface. Here, we present a unified and consistent view of the structure of the air/solution interface of aqueous electrolytes containing monovalent inorganic ions. Molecular dynamics calculations show that in salt solutions and bases the positively charged ions, such as alkali cations, are repelled from the interface, whereas the anions, such as halides or hydroxide, exhibit a varying surface propensity, correlated primarily with the ion polarizability and size. The behavior of acids is different due to a significant propensity of hydronium cations for the air/solution interface. Therefore, both cations and anions exhibit enhanced concentrations at the surface and, consequently, these acids (unlike bases and salts) reduce the surface tension of water. The results of the simulations are supported by surface selective nonlinear vibrational spectroscopy, which reveals among other things that the hydronium cations are present at the air/solution interface. The ion specific propensities for the air/solution interface have important implications for a whole range of heterogeneous physical and chemical processes, including atmospheric chemistry of aerosols, corrosion processes, and bubble coalescence.

Intermolecular hydrogen bonds in hetero-complexes of biologically active aromatic molecules probed by the methods of vibrational spectroscopy

NASA Astrophysics Data System (ADS)

Semenov, M. A.; Blyzniuk, Iu. N.; Bolbukh, T. V.; Shestopalova, A. V.; Evstigneev, M. P.; Maleev, V. Ya.

2012-09-01

By the methods of vibrational spectroscopy (Infrared and Raman) the investigation of the hetero-association of biologically active aromatic compounds: flavin-mononucleotide (FMN), ethidium bromide (EB) and proflavine (PRF) was performed in aqueous solutions. It was shown that between the functional groups (Cdbnd O and NH2) the intermolecular hydrogen bonds are formed in the hetero-complexes FMN-EB and FMN-PRF, additionally stabilizing these structures. An estimation of the enthalpy of Н-bonding obtained from experimental shifts of carbonyl vibrational frequencies has shown that the H-bonds do not dominate in the magnitude of experimentally measured total enthalpy of the hetero-association reactions. The main stabilization is likely due to intermolecular interactions of the molecules in these complexes and their interaction with water environment.

Study of complex molecular systems by probe vibrational spectroscopy method

NASA Astrophysics Data System (ADS)

Boldeskul, A. E.; Zatsepin, V. M.; Atakhodjaev, A. K.; Shermatov, A. N.; Ashburiev, R.

1984-03-01

Experimental study of benzonitril as a probe in aqueous solution of sodium lauril sulphate /SDS/ by Raman spectroscopy technique showed integral moments of √ /C X N/ line to be extremely sensitive to the structural transitions in micellar systems. The central part of the experimental contour was used to determine integral moments with the help of line shape approximant received by Mori method

Theoretical Studies on Heavy Metal Sulfides in Solution

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

Tossell, John A.

2007-10-31

'Calculating the stabilities, Raman and UV spectra and acidities of As sulfides in aqueous solution', J. A. Tossell, M. D. Zimmermann and G. R. Helz. Some of the Raman spectra obtained by reacting aqueous As(OH)3 with aqueous bisulfide are shown, taken from Wood, et al. (2002). To interpret these spectra we have carried out an extensive series of calculations, detailed for the case of AsS(SH){sub 2}{sup -} in Table 1 below. By employing state of the art quantum chemical techniques to determine gas-phase harmonic and anharmonic frequencies and solution phase corrections we can accurately match features in the experimental spectrummore » shown in the top figure. The AsS(SH){sub 2}{sup -}...22 H{sub 2}O nanocluster employed is shown in the lower figure. For this species we have calculated the equilibrium structure and the harmonic vibrational spectrum at the CBSB7 B3LYP level. For the free solute species AsS(SH){sub 2}{sup -} we have carried out a whole series of calculations, evaluating harmonic and anharmonic vibrational frequencies at a number of different quantum mechanical levels. In the spectra below, Fig. 3 and Fig. 5 from Wood, et al. (2002), the features around 700-800 cm{sup -1} are attributed to As-O stretches and those around 350-450 cm{sup -1} to As-S stretches. In the nanocluster an isolated vibrational feature is observed at 425 cm{sup -1}, an As=S stretch, close to the value (415 cm{sup -1}) determined by Wood, et al. (2002). Analysis of the calculated frequencies for AsS(SH){sub 2}{sup -} within a polarizable continuum model yields a similar result. Taking the highest level harmonic results, obtained from a CCSD calculation, and adding anharmonic and PCM corrections at the B3LYP level (designated (3) + (5) - (1) in Table 1) gives a frequency for the intense high frequency As=S stretch within 15 cm{sup -1} of experiment. Although there is still interesting work to be done on the stabilities and the Raman and UV spectra of As sulfides, most of the basic concepts have been worked out and we are therefore proposing to move to a new area, that of humic acids (while continuing our studies complexes formed by As oxides and sulfides, now applied to functional groups present in humic acids).« less

Water Interfaces, Solvation, and Spectroscopy

NASA Astrophysics Data System (ADS)

Geissler, Phillip L.

2013-04-01

Liquid water consistently expands our appreciation of the rich statistical mechanics that can emerge from simple molecular constituents. Here I review several interrelated areas of recent work on aqueous systems that aim to explore and explain this richness by revealing molecular arrangements, their thermodynamic origins, and the timescales on which they change. Vibrational spectroscopy of OH stretching features prominently in these discussions, with an emphasis on efforts to establish connections between spectroscopic signals and statistics of intermolecular structure. For bulk solutions, the results of these efforts largely verify and enrich existing physical pictures of hydrogen-bond network connectivity, dynamics, and response. For water at interfaces, such pictures are still emerging. As an important example I discuss the solvation of small ions at the air-water interface, whose surface propensities challenge a basic understanding of how aqueous fluctuations accommodate solutes in heterogeneous environments.

In-situ spectroscopic investigations of the redox behavior of poly(indole-5-carboxylic-acid) modified electrodes in acidic aqueous solutions.

PubMed

Talbi, H; Billaud, D; Louarn, G; Pron, A

2001-03-01

The oxidation of electrochemically grown poly(indole-5-carboxylic-acid) (P5CO2H) and its spectroscopic properties have been studied by in-situ spectroelectrochemical techniques. The purpose of this paper is to characterize the different modifications on the P5CO2H backbone, induced by the electrochemical oxidation in aqueous acidic solution. We have identified, on the basis of Raman spectra, the vibrational modes associated with neutral and oxidized segments of polymer. It was shown that at least three chemically and optically different species (perhaps other products too) are produced in different potential regimes upon oxidation of this polymer. The results obtained also indicate that the molecular properties of this conducting polymer are better revealed by in-situ resonant spectra than by ex-situ infrared and Raman studies.

Evidence of dithionite contribution to the low-frequency resonance Raman spectrum of reduced and mixed-valence cytochrome c oxidase.

PubMed

Centeno, J A

1992-02-01

The resonance Raman spectra of deoxygenated solutions of mixed-valence cyanide-bound and fully reduced cytochrome oxidase derivatives that have been reduced in the presence of aqueous or solid sodium dithionite exhibit two new low-frequency lines centered at 474 and 590 cm-1. These lines were not observed when the reductant system was changed to a solution containing ascorbate and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD). Under enzyme turnover conditions, the addition of dithionite to the reoxidized protein (the 428-nm or "oxygenated" form) increases the intensity of these lines, while reoxidation and rereduction of the enzyme in the presence of ascorbate/TMPD resulted in the absence of both lines. Our data suggest that both lines must have contributions from species formed from aqueous dithionite, presumably the SO2 species, since these two lines are also observed in the Raman spectrum of a solution of aqueous dithionite, but not in the spectrum of an ascorbate/TMPD solution. Since heme metal-ligand stretch vibrations are expected to appear in the low-frequency region from 215 to 670 cm-1, our results indicate that special care should be exercised during the interpretation of the cytochrome a3 resonance Raman spectrum.

The water-hydrophobic interface: neutral and charged solute adsorption at fluorocarbon and hydrocarbon self-assembled monolayers (SAMs).

PubMed

Hopkins, Adam J; Richmond, Geraldine L

2013-03-01

Adsorption of small molecular solutes in an aqueous solution to a soft hydrophobic surface is a topic relevant to many fields. In biological and industrial systems, the interfacial environment is often complex, containing an array of salts and organic compounds in the solution phase. Additionally, the surface itself can have a complex structure that can interact in unpredictable ways with small solutes in its vicinity. In this work, we studied model adsorption processes on hydrocarbon and fluorocarbon self-assembled monolayers by using vibrational sum frequency spectroscopy, with methanol and butylammonium chloride as adsorbates. The results indicate that differences in surface functionality have a significant impact on the organization of adsorbed organic species at hydrophobic surfaces.

Vibrational studies of phosphoryl transfer enzymes: ras- p21(*)magnesium-GTP and Myosin S1(*)magnesium-ADP- vanadate

NASA Astrophysics Data System (ADS)

Wang, Jianghua

1999-07-01

We have measured the Raman spectra of monophosphate compounds in aqueous solution. The measured frequencies were correlated with P••O valence bond order by using a modification of the Hardcastle- Wachs procedure. The P••O bond order and bond length in phosphates can be determined from vibrational spectra by using the derived bond order/stretching frequency correlation and the bond length/bond order correlation of Brown and Wu. The Raman and infrared spectra of guanosine 5'-diphosphate (GDP) and guanosine 5'-triphosphate (GTP) in aqueous solution were also examined. Frequency shifts were observed as Mg2+ complexes with GDP and GTP in aqueous solution. These results suggested that Mg2+ binds to GDP in a bidentate manner to the α,β P••O bonds and in a tridentate manner to the α,β and γ P••O bonds of Mg•GTP . We have analyzed the previously obtained isotope edited Raman difference spectra of 1:1 complexes of Mg•GDP and Mg•GTP in ras-p21. Frequency changes of the phosphate groups were observed when Mg•GDP , Mg•GTP bind to the protein. Employing both the previous empirical relationships between bond orders/lengths and frequencies as well as vibrational analysis from ab initio calculations, the spectral changes can be explained by the change of the Mg2+ binding sites and hydrogen-bonding. Implications of these structural results for the reaction mechanism of GTP hydrolysis catalyzed by the GTPase are discussed. We have analyzed previously obtained isotope edited Raman difference spectra of the non-bridging V••O bonds of vanadates, both in solution, and when bound to the myosin S1•MgADP complex. By use of ab initio calculations on a model of the vanadate binding site in myosin, the angles between the non-bridging V••O bonds and between these bonds and the apical bonds in the myosin S1•MgADP -Vi complex were determined. The summed bond order of the two apical bonds between the attacking and leaving group oxygens with the central vanadium ion in the S1•MgADP -Vi complex was found to increase only slightly compared with the bond order of the ester V-O bond of a monoester vanadate model compound in solution, suggesting an SN2 like mechanism for the phosphoryl transfer reaction catalyzed by myosin.

Sorption of As(V) on aluminosilicates treated with Fe(II) nanoparticles.

PubMed

Dousová, Barbora; Grygar, Tomás; Martaus, Alexandr; Fuitová, Lucie; Kolousek, David; Machovic, Vladimír

2006-10-15

Adsorption of arsenic on clay surfaces is important for the natural and simulated removal of arsenic species from aqueous environments. In this investigation, three samples of clay minerals (natural metakaoline, natural clinoptilolite-rich tuff, and synthetic zeolite) in both untreated and Fe-treated forms were used for the sorption of arsenate from model aqueous solution. The treatment of minerals consisted of exposing them to concentrated solution of Fe(II). Within this process the mineral surface has been laden with Fe(III) oxi(hydroxides) whose high affinity for the As(V) adsorption is well known. In all investigated systems the sorption capacity of Fe(II)-treated sorbents increased significantly in comparison to the untreated material (from about 0.5 to >20.0 mg/g, which represented more than 95% of the total As removal). The changes of Fe-bearing particles in the course of treating process and subsequent As sorption were investigated by the diffuse reflectance spectroscopy and the voltammetry of microparticles. IR spectra of treated and As(V)-saturated solids showed characteristic bands caused by Fe(III)SO(4), Fe(III)O, and AsO vibrations. In untreated As(V)-saturated solids no significant AsO vibrations were observed due to the negligible content of sorbed arsenate.

Adsorption kinetics of magnetic biochar derived from peanut hull on removal of Cr (VI) from aqueous solution: Effects of production conditions and particle size.

PubMed

Han, Yitong; Cao, Xi; Ouyang, Xin; Sohi, Saran P; Chen, Jiawei

2016-02-01

Magnetic biochar was made from peanut hull biomass using iron chloride in a simplified aqueous phase approach and pyrolysis at alternative peak temperatures (450-650 °C). Magnetic biochar showed an extreme capacity for adsorption of hexavalent chromium Cr (VI) from aqueous solution, which was 1-2 orders of magnitude higher compared to standard (non-magnetic) biochar from the same feedstock. Adsorption increased with pyrolysis temperature peaking at 77,542 mg kg(-1) in the sample pyrolysed at 650 °C. In contrast to magnetic biochar, the low adsorption capacity of standard biochar decreased with increasing pyrolysis temperature. The fine particle size of magnetic biochar and low aqueous pH were also important for adsorption. Surfaces of products from batch adsorption experiments were characterized by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, X-ray photoelectron spectroscopy and vibrating sample magnetometer. This revealed that γ-Fe2O3 was crucial to the properties (adsorbance and magnetism) of magnetic biochar. The removal mechanism was the Cr (VI) electrostatic attracted on protonated -OH on γ-Fe2O3 surface and it could be desorbed by alkaline solution. Findings suggest that pyrolysis has potential to create effective, magnetically recoverable adsorbents relevant to environmental application. Copyright © 2015 Elsevier Ltd. All rights reserved.

FTIR spectroscopic study of the phytohormone auxin (Indol-3-ylacetic Acid, IAA) and its n-alkylated and monohalogenated derivatives

NASA Astrophysics Data System (ADS)

Lutz, Bert T. G.; van der Windt, Erik; Kanters, Jan; Klämbt, Dieter; Kojić-Prodić, Biserka; Ramek, Michael

1996-09-01

In the framework of structure/activity correlation studies the plant growth hormone auxin and its natural analogue 4-Cl-IAA, as well as their synthetic congeners, were studied by FTIR spectroscopy. The analysis was focused on the NH and CO stretching vibrations which can be the most sensitive probes of intra- and intermolecular interactions, particularly to hydrogen bonds. However, it emerged that vC = O vibrations of both monomer and dimer are not affected by substitution. The aliphatic CH 2 group acts as an insulator between the conjugated π-system of indole and the carboxylic group, thus prohibiting a direct effect on the vibration CO. On the contrary, the stretching vibrations NH are influenced by halogenation and hydrogen bonding. The experimental data are in good agreement with the results of quantum chemical ab initio calculations of NH vibrations for IAA and several chlorine substituted IAAs. However, a simple correlation between substitution and spectral properties of indole NH cannot be found. The measurements were performed in the solid state (KBr pellets) and in polar (diethylether) and nonpolar (CDCI 3) solutions. From the measurements in diethylether, it follows that in dilute solution IAA and derivatives are predominantly present as monomer, whereas in CDCl 3 the equilibrium is in favour of the dimer form. In aqueous solution at the concentrations used in growth experiments solvated monomer will be the active component. Bioactivity of auxin and analogues with their NH stretching frequency shifts cannot be correlated in a simple way.

Intermolecular hydrogen bonds in hetero-complexes of biologically active aromatic molecules probed by the methods of vibrational spectroscopy.

PubMed

Semenov, M A; Blyzniuk, Iu N; Bolbukh, T V; Shestopalova, A V; Evstigneev, M P; Maleev, V Ya

2012-09-01

By the methods of vibrational spectroscopy (Infrared and Raman) the investigation of the hetero-association of biologically active aromatic compounds: flavin-mononucleotide (FMN), ethidium bromide (EB) and proflavine (PRF) was performed in aqueous solutions. It was shown that between the functional groups (CO and NH(2)) the intermolecular hydrogen bonds are formed in the hetero-complexes FMN-EB and FMN-PRF, additionally stabilizing these structures. An estimation of the enthalpy of Н-bonding obtained from experimental shifts of carbonyl vibrational frequencies has shown that the H-bonds do not dominate in the magnitude of experimentally measured total enthalpy of the hetero-association reactions. The main stabilization is likely due to intermolecular interactions of the molecules in these complexes and their interaction with water environment. Copyright © 2012 Elsevier B.V. All rights reserved.

Experimental and theoretical vibrational spectroscopy studies of acetohydroxamic acid and desferrioxamine B in aqueous solution: Effects of pH and iron complexation

NASA Astrophysics Data System (ADS)

Edwards, David C.; Nielsen, Steen B.; Jarzęcki, Andrzej A.; Spiro, Thomas G.; Myneni, Satish C. B.

2005-07-01

The deprotonation and iron complexation of the hydroxamate siderophore, desferrioxamine B (desB), and a model hydroxamate ligand, acetohydroxamic acid (aHa), were studied using infrared, resonance Raman and UV-vis spectroscopy. The experimental spectra were interpreted by a comparison with DFT calculated spectra of aHa (partly hydrated) and desB (reactive groups of unhydrated molecule) at the B3LYP/6-31G* level of theory. The ab initio models include three water molecules surrounding the deprotonation site of aHa to account for partial hydration. Experiments and calculations were also conducted in D 2O to verify spectral assignments. These studies of aHa suggest that the cis-keto-aHa is the dominant form, and its deprotonation occurs at the oxime oxygen atom in aqueous solutions. The stable form of iron-complexed aHa is identified as Fe(aHa) 3 for a wide range of pH conditions. The spectral information of aHa and an ab initio model of desB were used to interpret the chemical state of different functional groups in desB. Vibrational spectra of desB indicate that the oxime and amide carbonyl groups can be identified unambiguously. Vibrational spectral analysis of the oxime carbonyl after deprotonation and iron complexation of desB indicates that the conformational changes between anion and the iron-complexed anion are small. Enhanced electron delocalization in the oxime group of Fe-desB when compared to that of Fe(aHa) 3 may be responsible for higher stability constant of the former.

Excited-state dynamics of mononucleotides and DNA strands in a deep eutectic solvent.

PubMed

Zhang, Yuyuan; de La Harpe, Kimberly; Hariharan, Mahesh; Kohler, Bern

2018-04-17

The photophysics of several mono- and oligonucleotides were investigated in a deep eutectic solvent for the first time. The solvent glyceline, prepared as a 1 : 2 mole ratio mixture of choline chloride and glycerol, was used to study excited-state deactivation in a non-aqueous solvent by the use of steady-state and time-resolved spectroscopy. DNA strands in glyceline retain the secondary structures that are present in aqueous solution to some degree, thus enabling a study of the effects of solvent properties on the excited states of stacked bases and stacked base pairs. The excited-state lifetime of the mononucleotide 5'-AMP in glyceline is 630 fs, or twice as long as in aqueous solution. Even slower relaxation is seen for 5'-TMP in glyceline, and a possible triplet state with a lifetime greater than 3 ns is observed. Circular dichroism spectra show that the single strand (dA)18 and the duplex d(AT)9·d(AT)9 adopt similar structures in glyceline and in aqueous solution. Despite having similar conformations in both solvents, femtosecond transient absorption experiments reveal striking changes in the dynamics. Excited-state decay and vibrational cooling generally take place more slowly in glyceline than in water. Additionally, the fraction of long-lived excited states in both oligonucleotide systems is lower in glyceline than in aqueous solution. For a DNA duplex, water is suggested to favor decay pathways involving intrastrand charge separation, while the deep eutectic solvent favors interstrand deactivation channels involving neutral species. Slower solvation dynamics in the viscous deep eutectic solvent may also play a role. These results demonstrate that the dynamics of excitations in stacked bases and stacked base pairs depend not only on conformation, but are also highly sensitive to the solvent.

Vibrational spectroscopic determination of local solvent electric field, solute-solvent electrostatic interaction energy, and their fluctuation amplitudes.

PubMed

Lee, Hochan; Lee, Gayeon; Jeon, Jonggu; Cho, Minhaeng

2012-01-12

IR probes have been extensively used to monitor local electrostatic and solvation dynamics. Particularly, their vibrational frequencies are highly sensitive to local solvent electric field around an IR probe. Here, we show that the experimentally measured vibrational frequency shifts can be inversely used to determine local electric potential distribution and solute-solvent electrostatic interaction energy. In addition, the upper limits of their fluctuation amplitudes are estimated by using the vibrational bandwidths. Applying this method to fully deuterated N-methylacetamide (NMA) in D(2)O and examining the solvatochromic effects on the amide I' and II' mode frequencies, we found that the solvent electric potential difference between O(═C) and D(-N) atoms of the peptide bond is about 5.4 V, and thus, the approximate solvent electric field produced by surrounding water molecules on the NMA is 172 MV/cm on average if the molecular geometry is taken into account. The solute-solvent electrostatic interaction energy is estimated to be -137 kJ/mol, by considering electric dipole-electric field interaction. Furthermore, their root-mean-square fluctuation amplitudes are as large as 1.6 V, 52 MV/cm, and 41 kJ/mol, respectively. We found that the water electric potential on a peptide bond is spatially nonhomogeneous and that the fluctuation in the electrostatic peptide-water interaction energy is about 10 times larger than the thermal energy at room temperature. This indicates that the peptide-solvent interactions are indeed important for the activation of chemical reactions in aqueous solution.

Abiotic degradation of glyphosate into aminomethylphosphonic acid in the presence of metals.

PubMed

Ascolani Yael, J; Fuhr, J D; Bocan, G A; Daza Millone, A; Tognalli, N; Dos Santos Afonso, M; Martiarena, M L

2014-10-08

Glyphosate [N-phosphono-methylglycine (PMG)] is the most used herbicide worldwide, particularly since the development of transgenic glyphosate-resistant (GR) crops. Aminomethylphosphonic acid (AMPA) is the main glyphosate metabolite, and it may be responsible for GR crop damage upon PMG application. PMG degradation into AMPA has hitherto been reckoned mainly as a biological process, produced by soil microorganisms (bacteria and fungi) and plants. In this work, we use density functional calculations to identify the vibrational bands of PMG and AMPA in surface-enhanced Raman spectroscopy (SERS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra experiments. SERS shows the presence of AMPA after glyphosate is deposited from aqueous solution on different metallic surfaces. AMPA is also detected in ATR-FTIR experiments when PMG interacts with metallic ions in aqueous solution. These results reveal an abiotic degradation process of glyphosate into AMPA, where metals play a crucial role.

Efficient Removal of Uranium from Aqueous Solution by Reduced Graphene Oxide-Zn0.5Ni0.5Fe2O4 Ferrite-Polyaniline Nanocomposite

NASA Astrophysics Data System (ADS)

Tran, Dat Quang; Pham, Hung Thanh; Do, Hung Quoc

2017-06-01

Reduced graphene oxide-Zn0.5Ni0.5Fe2O4 ferrite-polyaniline nanocomposite (RGO-ZNF-PANI) was synthesized by a three-step method. The prepared samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy and vibrating sample magnetometer. In particular, we found that this material is capable of effectively removing uranium from an aquatic environment. This is confirmed by our experimental results using the method of inductively coupled plasma mass spectrometry. Adsorptive behaviour of uranium from an aqueous solution on the RGO-ZNF-PANI nanocomposite was examined as a function of pH, contact time, and equilibrium. Uranium concentration was carried out by batch techniques. The adsorption isotherm agrees well with the Langmuir model, having a maximum sorption capacity of 1885 mg/g, at pH 5 and 25°C.

UV-vis and Raman spectroelectrochemical investigation of the redox behavior of poly(5-cyanoindole) in acidic aqueous solutions.

PubMed

Talbi, H; Billaud, D; Louarn, G; Pron, A

2000-03-01

Spectroelectrochemical properties of conducting poly(5-cyanoindole) films deposited on indium tin oxide (ITO) and platinum electrodes are investigated using UV-vis and resonant Raman spectroscopies. The transitions from undoped to semi-conducting state of P5CN require the partial oxidation of the polymer to create radical-cations by insertion of charge-neutralizing anions into the polymer. In order to obtain detailed structural information from the vibrational spectra, it is necessary to know the vibrational modes of oxidation-sensitive bands. Vibrational assignments were made on the basis of the results obtained on polyindole and P5CN in acetonitrile solution. The drastic changes in optical absorption and Raman spectra observed at various stage of oxidation were explained by the conversions between at least three different structures. On the basis of the Raman spectra, we have identified the vibrational modes associated with neutral and polaronic segments. The perturbation associated with the coexistence of these polaronic segments has been described as a quinoid structure growing on the expense of the benzoid one. The results obtained indicate that the molecular properties of the conducting polymers at various stages of an oxidation are better revealed by in-situ Raman spectra than by ex-situ studies.

The peculiarities of spectral manifestations of high-voltage electric discharge in different phase states of ion systems.

PubMed

Gafurov, M M; Aliev, A R; Ataev, M B; Rabadanov, K Sh

2013-10-01

The effects of high-voltage pulsed discharge (HVPD activation) on vibrational spectra of ion salt systems have been studied. The peculiarities of spectral display of HVPD in ion melts and aqueous solutions of electrolytes, in ion-conducting phases of crystalline and glassy salt systems have been investigated. After HVPD a salt system is in non-equilibrium activated state. In the activated state of a salt system, the relaxation time of the vibrational excited states of molecular ions is shorter than in the equilibrium state if the vibrational relaxation rate increases with temperature in the system. For those systems for which the relaxation rate decreases at elevated temperatures, the relaxation time of the vibrational excited states of molecular ions is longer than in the equilibrium state. HVPD activation of a salt system can change the configuration of the electron shell of molecular ions. Therefore, the lifetime values of activated state of salt systems are abnormally large. Copyright © 2013 Elsevier B.V. All rights reserved.

Understanding the Origins of Dipolar Couplings and Correlated Motion in the Vibrational Spectrum of Water.

PubMed

Heyden, Matthias; Sun, Jian; Forbert, Harald; Mathias, Gerald; Havenith, Martina; Marx, Dominik

2012-08-16

The combination of vibrational spectroscopy and molecular dynamics simulations provides a powerful tool to obtain insights into the molecular details of water structure and dynamics in the bulk and in aqueous solutions. Applying newly developed approaches to analyze correlations of charge currents, molecular dipole fluctuations, and vibrational motion in real and k-space, we compare results from nonpolarizable water models, widely used in biomolecular modeling, to ab initio molecular dynamics. For the first time, we unfold the infrared response of bulk water into contributions from correlated fluctuations in the three-dimensional, anisotropic environment of an average water molecule, from the OH-stretching region down to the THz regime. Our findings show that the absence of electronic polarizability in the force field model not only results in differences in dipolar couplings and infrared absorption but also induces artifacts into the correlated vibrational motion between hydrogen-bonded water molecules, specifically at the intramolecular bending frequency. Consequently, vibrational motion is partially ill-described with implications for the accuracy of non-self-consistent, a posteriori methods to add polarizability.

Ricin, ricin agglutinin, and the ricin binding subunit structural comparison by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Brandt, N. N.; Chikishev, A. Yu.; Sotnikov, A. I.; Savochkina, Yu. A.; Agapov, I. I.; Tonevitsky, A. G.

2005-02-01

Raman spectroscopy is used to study conformation-sensitive vibrational bands of the plant toxins ricin and ricin agglutinin and the ricin binding subunit in aqueous solution. The analysis of the Raman data yields the conformational state of the protein molecules differing from that predicted by the X-ray data. The differences and similarities in the conformational state of ricin, ricin agglutinin, and ricin binding subunit are discussed.

Crystal structure and vibrational spectra of melaminium arsenate

NASA Astrophysics Data System (ADS)

Anbalagan, G.; Marchewka, M. K.; Pawlus, K.; Kanagathara, N.

2015-01-01

The crystals of the new melaminium arsenate (MAS) [C3H7N6+ṡH2AsO4-] were obtained by the slow evaporation of an aqueous solution at room temperature. Single crystal X-ray diffraction analysis reveals that the crystal belongs to triclinic system with centro symmetric space group P-1. The crystals are built up from single protonated melaminium residues and single dissociated arsenate H2AsO4- anions. The protonated melaminium ring is almost planar. A combination of ionic and donor-acceptor hydrogen-bond interactions linking together the melaminium and arsenate residues forms a three-dimensional network. Vibrational spectroscopic analysis is reported on the basis of FT-IR and FT-Raman spectra recorded at room temperature. Hydrogen bonded network present in the crystal gives notable vibrational effect. DSC has also been performed for the crystal shows no phase transition in the studied temperature range (113-293 K).

Quenching of light flickering in synthetic guanine crystals in aqueous solutions under strong static magnetic fields

NASA Astrophysics Data System (ADS)

Mootha, A.; Takanezawa, Y.; Iwasaka, M.

2018-05-01

The present study focused on the vibration of micro crystal particles of guanine due to Brownian motion. The organic particle has a refractive index of 1.83 and caused a flickering of light. To test the possibility of using magnetic properties under wet conditions, changes in the frequency of particle vibration by applying magnetic fields were investigated. At first, we found that the exposure at 5 T inhibited the flickering light intensities and the particle vibration slightly decreased. Next, we carried out a high speed camera measurement of the Brownian motion of the particle with a time resolution of 100 flame per second (fps) with and without magnetic field exposures. It was revealed that the vibrational speed of synthetic particles was enhanced at 500 mT. Detailed analyses of the particle vibration by changing the direction of magnetic fields versus the light source revealed that the Brownian motion's vibrational frequency was entrained under magnetic fields at 500 mT, and an increase in vibration speed to 20Hz was observed. Additional measurements of light scattering fluctuation using photo-detector and analyses on auto-correlation also confirmed this speculation. The studied Brownian vibration may be influenced by the change in mechanical interactions between the vibration particles and surrounding medium. The discovered phenomena can be applied for molecular and biological interactions in future studies.

On the vibrational characteristics of single- and double-walled carbon nanotubes containing ice nanotube in aqueous environment

NASA Astrophysics Data System (ADS)

Ansari, R.; Ajori, S.; Ameri, A.

2015-10-01

The properties and behavior of carbon nanotubes (CNTs) in aqueous environment due to their considerable potential applications in nanobiotechnology and designing nanobiosensors have attracted the attention of researchers. In this study, molecular dynamics simulations are carried out to investigate the vibrational characteristics of single- and double-walled CNTs containing ice nanotubes (a new phase of ice) in vacuum and aqueous environments. The results demonstrate that formation of ice nanotubes inside the CNTs reduces the natural frequency of pure CNTs. Moreover, it is demonstrated that increasing the number of walls considerably reduces the sensitivity of frequency to the presence of ice nanotube inside CNT. Additionally, it is shown that increasing the length decreases the effect of ice nanotube on reducing the frequency. The calculation of natural frequency of CNTs in aqueous media demonstrates that the interaction of CNTs with water molecules considerably reduces the natural frequency up to 50 %. Finally, it is demonstrated that in the case of CNTs with one free end in aqueous environment, the CNT does not vibrate in its first mode, and its frequency is between the frequencies of first and second modes of vibration.

Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions.

PubMed

Choi, Jun-Ho; Lee, Hochan; Choi, Hyung Ran; Cho, Minhaeng

2018-04-20

In molecular and cellular biology, dissolved ions and molecules have decisive effects on chemical and biological reactions, conformational stabilities, and functions of small to large biomolecules. Despite major efforts, the current state of understanding of the effects of specific ions, osmolytes, and bioprotecting sugars on the structure and dynamics of water H-bonding networks and proteins is not yet satisfactory. Recently, to gain deeper insight into this subject, we studied various aggregation processes of ions and molecules in high-concentration salt, osmolyte, and sugar solutions with time-resolved vibrational spectroscopy and molecular dynamics simulation methods. It turns out that ions (or solute molecules) have a strong propensity to self-assemble into large and polydisperse aggregates that affect both local and long-range water H-bonding structures. In particular, we have shown that graph-theoretical approaches can be used to elucidate morphological characteristics of large aggregates in various aqueous salt, osmolyte, and sugar solutions. When ion and molecular aggregates in such aqueous solutions are treated as graphs, a variety of graph-theoretical properties, such as graph spectrum, degree distribution, clustering coefficient, minimum path length, and graph entropy, can be directly calculated by considering an ensemble of configurations taken from molecular dynamics trajectories. Here we show percolating behavior exhibited by ion and molecular aggregates upon increase in solute concentration in high solute concentrations and discuss compelling evidence of the isomorphic relation between percolation transitions of ion and molecular aggregates and water H-bonding networks. We anticipate that the combination of graph theory and molecular dynamics simulation methods will be of exceptional use in achieving a deeper understanding of the fundamental physical chemistry of dissolution and in describing the interplay between the self-aggregation of solute molecules and the structure and dynamics of water.

Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Choi, Jun-Ho; Lee, Hochan; Choi, Hyung Ran; Cho, Minhaeng

2018-04-01

In molecular and cellular biology, dissolved ions and molecules have decisive effects on chemical and biological reactions, conformational stabilities, and functions of small to large biomolecules. Despite major efforts, the current state of understanding of the effects of specific ions, osmolytes, and bioprotecting sugars on the structure and dynamics of water H-bonding networks and proteins is not yet satisfactory. Recently, to gain deeper insight into this subject, we studied various aggregation processes of ions and molecules in high-concentration salt, osmolyte, and sugar solutions with time-resolved vibrational spectroscopy and molecular dynamics simulation methods. It turns out that ions (or solute molecules) have a strong propensity to self-assemble into large and polydisperse aggregates that affect both local and long-range water H-bonding structures. In particular, we have shown that graph-theoretical approaches can be used to elucidate morphological characteristics of large aggregates in various aqueous salt, osmolyte, and sugar solutions. When ion and molecular aggregates in such aqueous solutions are treated as graphs, a variety of graph-theoretical properties, such as graph spectrum, degree distribution, clustering coefficient, minimum path length, and graph entropy, can be directly calculated by considering an ensemble of configurations taken from molecular dynamics trajectories. Here we show percolating behavior exhibited by ion and molecular aggregates upon increase in solute concentration in high solute concentrations and discuss compelling evidence of the isomorphic relation between percolation transitions of ion and molecular aggregates and water H-bonding networks. We anticipate that the combination of graph theory and molecular dynamics simulation methods will be of exceptional use in achieving a deeper understanding of the fundamental physical chemistry of dissolution and in describing the interplay between the self-aggregation of solute molecules and the structure and dynamics of water.

A Density Functional Theory Evaluation of Hydrophobic Solvation: Ne, Ar and Kr in a 50-Water Cluster. Implications for the Hydrophobic Effect.

PubMed

Kobko, Nadya; Marianski, Mateusz; Asensio, Amparo; Wieczorek, Robert; Dannenberg, J J

2012-06-15

The physical explanation for the hydrophobic effect has been the subject of disagreement. Physical organic chemists tend to use a explanation related to pressure, while many biochemists prefer an explanation that involves decreased entropy of the aqueous solvent. We present DFT calculations at the B3LYP/6-31G(d,p) and X3LYP/6-31G(d,p) levels on the solvation of three noble gases (Ne, Ar, and Kr) in clusters of 50 waters. Vibrational analyses show no substantial decreases in the vibrational entropies of the waters in any of the three clusters. The observed positive free energies of transfer from the gas phase or from nonpolar solvents to water appear to be due to the work needed to make a suitable hole in the aqueous solvent. We distinguish between hydrophobic solvations (explicitly studied here) and the hydrophobic effect that occurs when a solute (or transition state) can decrease its volume through conformational change (which is not possible for the noble gases).

A Density Functional Theory Evaluation of Hydrophobic Solvation: Ne, Ar and Kr in a 50-Water Cluster. Implications for the Hydrophobic Effect

PubMed Central

Kobko, Nadya; Marianski, Mateusz; Asensio, Amparo; Wieczorek, Robert; Dannenberg, J. J.

2011-01-01

The physical explanation for the hydrophobic effect has been the subject of disagreement. Physical organic chemists tend to use a explanation related to pressure, while many biochemists prefer an explanation that involves decreased entropy of the aqueous solvent. We present DFT calculations at the B3LYP/6-31G(d,p) and X3LYP/6-31G(d,p) levels on the solvation of three noble gases (Ne, Ar, and Kr) in clusters of 50 waters. Vibrational analyses show no substantial decreases in the vibrational entropies of the waters in any of the three clusters. The observed positive free energies of transfer from the gas phase or from nonpolar solvents to water appear to be due to the work needed to make a suitable hole in the aqueous solvent. We distinguish between hydrophobic solvations (explicitly studied here) and the hydrophobic effect that occurs when a solute (or transition state) can decrease its volume through conformational change (which is not possible for the noble gases). PMID:22666658

Modeling the IR spectra of aqueous metal carboxylate complexes: correlation between bonding geometry and stretching mode wavenumber shifts.

PubMed

Sutton, Catherine C R; da Silva, Gabriel; Franks, George V

2015-04-27

A widely used principle is that shifts in the wavenumber of carboxylate stretching modes upon bonding with a metal center can be used to infer if the geometry of the bonding is monodentate or bidentate. We have tested this principle with ab initio modeling for aqueous metal carboxylate complexes and have shown that it does indeed hold. Modeling of the bonding of acetate and formate in aqueous solution to a range of cations was used to predict the infrared spectra of the metal-carboxylate complexes, and the wavenumbers of the symmetric and antisymmetric vibrational modes are reported. Furthermore, we have shown that these shifts in wavenumber occur primarily due to how bonding with the metal changes the carboxylate C-O bond lengths and O-C-O angle. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isolation and Characterization of FORMATE/NI(CYCLAM)^{2+} Complexes with Cryogenic Ion Vibrational Predissociation

NASA Astrophysics Data System (ADS)

Wolk, Arron B.; Fournier, Joseph A.; Wolke, Conrad T.; Johnson, Mark A.

2013-06-01

Transition metal-based organometallic catalysts are a promising means of converting CO_{2} to transportable fuels. Ni(cyclam)^{2+}(cyclam = 1,4,8,11-tetraazacyclotetradecane), a Ni^{II} complex ligated by four nitrogen centers, has shown promise as a catalyst selective for CO_{2} reduction in aqueous solutions. The cyclam ligand has four NH hydrogen bond donors that can adopt five conformations, each offering distinct binding motifs for coordination of CO_{2} close to the metal center. To probe the ligand conformation and the role of hydrogen bonding in adduct binding, we extract Ni(cyclam)^{2+} complexes with the formate anion and some of its analogs from solution using electrospray ionization, and characterize their structures using cryogenic ion vibrational predissociation spectroscopy. Using the signature vibrational features of the embedded carboxylate anion and the NH groups as reporters, we compare the binding motifs of oxalate, benzoate, and formate anions to the Ni(cyclam)^{2+} framework. Finally, we comment on possible routes to generate the singly charged Ni(cyclam)^{+} complex, a key intermediate that has been invoked in the catalytic CO_{2} reduction cycle, but has never been isolated through ion processing techniques.

Dephasing dynamics in confined myoglobin

NASA Astrophysics Data System (ADS)

Goj, Anne; Loring, Roger F.

2007-11-01

Confinement of a solution can slow solvent dynamics and in turn influence the reactivity and structure of the solute. Encapsulating a protein in an aqueous pore affects its binding properties, stability to degradation, interconversion between conformational states, and energy relaxation. We perform molecular dynamics simulations of H64V-CO mutant myoglobin solvated by varying amounts of liquid water, and in turn enclosed by a matrix of immobilized solvent, to mimic differing degrees of confinement of H64V-CO in a glass. We calculate the three-pulse vibrational echo signal of the CO ligand from the autocorrelation function of fluctuations in the CO vibrational frequency. When the first solvation layer alone is free to relax, the correlation function displays only fast relaxation reminiscent of the case of a protein in a fixed, immobilized solvent matrix. However the vibrational echo signal in this case decays significantly more rapidly than for a static solvent. With two solvation layers mobile, the correlation function displays long time relaxation characteristic of the unconfined protein and the echo signal decays rapidly. The echo signal of the protein with two mobile solvation layers is nearly identical to that of the unconfined protein, despite the substantially constrained solvent dynamics in the confined case.

Structural study of human growth hormone-releasing factor fragment (1?29) by vibrational spectroscopy

NASA Astrophysics Data System (ADS)

Carmona, P.; Molina, M.; Lasagabaster, A.

1995-05-01

The conformational structure of fragment 1-29 of human growth hormone releasing factor, hGHRF (1-29), in aqueous solution and in the solid state is investigated by infrared and Raman spectroscopy. The polypeptide backbone is found to be unordered in the solid state. However, the spectra of the peptide prepared as 5% (w/w) aqueous solutions show that approximately 28% of the peptide is involved in intermolecular β-sheet aggregation. The remainder of the peptide exists largely as disordered and β-sheet conformations with a small portion of α-helices. Tyrosine residues are found to be exposed to the solvent. The secondary structures are quantitatively examined through infrared spectroscopy, the conformational percentages being near those obtained by HONDAet al. [ Biopolymers31, 869 (1991)] using circular dichroism. The fast hydrogen/deuterium exchange in peptide groups and the absence of any NMR sign indicative of ordered structure [ G. M. CLOREet al., J. Molec. Biol.191, 553 (1986)] support that the solution conformations of the non-aggregated peptide interconvert in dynamic equilibrium. Some physiological advantages that may derive from this conformational flexibility are also discussed

Comparative density functional study of the complexes [UO2(CO3)3]4- and [(UO2)3(CO3)6]6- in aqueous solution.

PubMed

Schlosser, Florian; Moskaleva, Lyudmila V; Kremleva, Alena; Krüger, Sven; Rösch, Notker

2010-06-28

With a relativistic all-electron density functional method, we studied two anionic uranium(VI) carbonate complexes that are important for uranium speciation and transport in aqueous medium, the mononuclear tris(carbonato) complex [UO(2)(CO(3))(3)](4-) and the trinuclear hexa(carbonato) complex [(UO(2))(3)(CO(3))(6)](6-). Focusing on the structures in solution, we applied for the first time a full solvation treatment to these complexes. We approximated short-range effects by explicit aqua ligands and described long-range electrostatic interactions via a polarizable continuum model. Structures and vibrational frequencies of "gas-phase" models with explicit aqua ligands agree best with experiment. This is accidental because the continuum model of the solvent to some extent overestimates the electrostatic interactions of these highly anionic systems with the bulk solvent. The calculated free energy change when three mono-nuclear complexes associate to the trinuclear complex, agrees well with experiment and supports the formation of the latter species upon acidification of a uranyl carbonate solution.

Calculation of the structures, stabilities, and vibrational spectra of arsenites, thioarsenites and thioarsenates in aqueous solution

NASA Astrophysics Data System (ADS)

Tossell, J. A.; Zimmermann, M. D.

2008-11-01

Structures, stabilities and vibrational spectra have been calculated using molecular quantum mechanical methods for As(OH) 3, AsO(OH) 3, As(SH) 3, AsS(SH) 3 and their conjugate bases and for several species with partial substitution of S for O. Properties for the neutral gas-phase molecules are calculated with state-of-the-art methods which yield As sbnd L distances within 0. 01 Å and As sbnd L stretching frequencies within 10 cm -1 of experiment. Similar accuracy is obtained for neutral molecules in solution using a polarizable continuum model (PCM). For monoanions such as AsO(OH)2- and AsS(SH)2-1 frequencies can be calculated to within 20 cm -1 of experiment using the polarizable continuum model. Multiply charged anions remain a challenge for accurate frequency calculations, but we have obtained results within the PCM model which at least semiquantitatively reproduce the available data. This allows us to assign the controversial features D, E and F in the Raman data of (Wood S. A., Tait C. D. and Janecky D. R. (2002) A Raman spectroscopic study of arsenite and thioarsenite species in aqueous solution at 25 °C. Geochem. Trans. 3, 31-39). To help in the assignment of the arsenic sulfide spectra we have also calculated energetics for the oxidation of As(III) to As(V) compounds by polysulfides, disproportionation of As(III) compounds and for the dissociation of the oxo- and thio-acids. We have determined that As(III) oxyacids can be transformed to thioacids which can in turn be oxidized to As(V) sulfides by polysulfides and that the p Ka1s of the acids involved can be ordered as follows: AsS(SH) 3 < As(SH) 3 < AsO(OH) 3 < As(OH) 3 in order of increasing p Ka1. We have also established from the calculated energies that the most stable form of the As(III) oxyacid in acidic aqueous solution is indeed As(OH) 3, consistent with previous assignments.

L-Nitroargininium picrate

NASA Astrophysics Data System (ADS)

Apreyan, R. A.; Fleck, M.; Atanesyan, A. K.; Sukiasyan, R. P.; Petrosyan, A. M.

2015-12-01

L-Nitroargininium picrate has been obtained from an aqueous solution containing equimolar quantities of L-nitroarginine and picric acid by slow evaporation. Single crystal was grown by evaporation method. Crystal structure was determined at room temperature. The salt crystallizes in monoclinic crystal system (space group P21). Vibrational spectra and thermal properties were studied. Second harmonic generation efficiency measured by powder method is found to be four times higher than in L-nitroarginine, which in turn is ten times more efficient than KDP (KH2PO4).

Non-invasive vibrational SFG spectroscopy reveals that bacterial adhesion can alter the conformation of grafted "brush" chains on SAM.

PubMed

Bulard, Emilie; Guo, Ziang; Zheng, Wanquan; Dubost, Henri; Fontaine-Aupart, Marie-Pierre; Bellon-Fontaine, Marie-Noëlle; Herry, Jean-Marie; Briandet, Romain; Bourguignon, Bernard

2011-04-19

Understanding bacterial adhesion on a surface is a crucial step to design new materials with improved properties or to control biofilm formation and eradication. Sum Frequency Generation (SFG) vibrational spectroscopy has been employed to study in situ the conformational response of a self-assembled monolayer (SAM) of octadecanethiol (ODT) on a gold film to the adhesion of hydrophilic and hydrophobic ovococcoid model bacteria. The present work highlights vibrational SFG spectroscopy as a powerful and unique non-invasive biophysical technique to probe and control bacteria interaction with ordered surfaces. Indeed, the SFG vibrational spectral changes reveal different ODT SAM conformations in air and upon exposure to aqueous solution or bacterial adhesion. Furthermore, this effect depends on the bacterial cell surface properties. The SFG spectral modeling demonstrates that hydrophobic bacteria flatten the ODT SAM alkyl chain terminal part, whereas the hydrophilic ones raise this ODT SAM terminal part. Microorganism-induced alteration of grafted chains can thus affect the desired interfacial functionality, a result that should be considered for the design of new reactive materials. © 2011 American Chemical Society

Structure and dynamics of the CrIII ion in aqueous solution: Ab initio QM/MM molecular dynamics simulation.

PubMed

Kritayakornupong, Chinapong; Plankensteiner, Kristof; Rode, Bernd M

2004-10-01

Structural and dynamical properties of the Cr(III) ion in aqueous solution have been investigated using a combined ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulation. The hydration structure of Cr(III) was determined in terms of radial distribution functions, coordination numbers, and angular distributions. The QM/MM simulation gives coordination numbers of 6 and 15.4 for the first and second hydration shell, respectively. The first hydration shell is kinetically very inert but by no means rigid and variations of the first hydration shell geometry lead to distinct splitting in the vibrational spectra of Cr(H(2)O)(6) (3+). A mean residence time of 22 ps was obtained for water ligands residing in the second hydration shell, which is remarkably shorter than the experimentally estimated value. The hydration energy of -1108 +/- 7 kcal/mol, obtained from the QM/MM simulation, corresponds well to the experimental hydration enthalpy value. Copyright 2004 Wiley Periodicals, Inc.

Structure from Dynamics: Vibrational Dynamics of Interfacial Water as a Probe of Aqueous Heterogeneity

PubMed Central

2018-01-01

The structural heterogeneity of water at various interfaces can be revealed by time-resolved sum-frequency generation spectroscopy. The vibrational dynamics of the O–H stretch vibration of interfacial water can reflect structural variations. Specifically, the vibrational lifetime is typically found to increase with increasing frequency of the O–H stretch vibration, which can report on the hydrogen-bonding heterogeneity of water. We compare and contrast vibrational dynamics of water in contact with various surfaces, including vapor, biomolecules, and solid interfaces. The results reveal that variations in the vibrational lifetime with vibrational frequency are very typical, and can frequently be accounted for by the bulk-like heterogeneous response of interfacial water. Specific interfaces exist, however, for which the behavior is less straightforward. These insights into the heterogeneity of interfacial water thus obtained contribute to a better understanding of complex phenomena taking place at aqueous interfaces, such as photocatalytic reactions and protein folding. PMID:29490138

Solvation of magnesium dication: molecular dynamics simulation and vibrational spectroscopic study of magnesium chloride in aqueous solutions.

PubMed

Callahan, Karen M; Casillas-Ituarte, Nadia N; Roeselová, Martina; Allen, Heather C; Tobias, Douglas J

2010-04-22

Magnesium dication plays many significant roles in biochemistry. While it is available to the environment from both ocean waters and mineral salts on land, its roles in environmental and atmospheric chemistry are still relatively unknown. Several pieces of experimental evidence suggest that contact ion pairing may not exist at ambient conditions in solutions of magnesium chloride up to saturation concentrations. This is not typical of most ions. There has been disagreement in the molecular dynamics literature concerning the existence of ion pairing in magnesium chloride solutions. Using a force field developed during this study, we show that contact ion pairing is not energetically favorable. Additionally, we present a concentration-dependent Raman spectroscopic study of the Mg-O(water) hexaaquo stretch that clearly supports the absence of ion pairing in MgCl(2) solutions, although a transition occurring in the spectrum between 0.06x and 0.09x suggests a change in solution structure. Finally, we compare experimental and calculated observables to validate our force field as well as two other commonly used magnesium force fields, and in the process show that ion pairing of magnesium clearly is not observed at higher concentrations in aqueous solutions of magnesium chloride, independent of the choice of magnesium force field, although some force fields give better agreement to experimental results than others.

Structural and vibrational properties of oxcarbazepine, an anticonvulsant substance by using DFT and SCRF calculations

NASA Astrophysics Data System (ADS)

Ladetto, María F.; Márquez, María B.; Brandán, Silvia A.

2014-10-01

In this work, we have presented a structural and vibrational study on the properties in gas and aqueous solution phases of oxcarbazepine, a polymorphic anticonvulsant substance, combining the available IR and Raman spectra with Density Functional Theory (DFT) calculations. Two stable C1 and C2 forms for the title molecule were theoretically determined by using the hybrid B3LYP/6-31G* method. The integral equation formalism variant polarised continuum model (IEFPCM) was employed to study the solvent effects by means of the self-consistent reaction field (SCRF) method. The vibrational spectra for the two forms of oxcarbazepine were completely assigned together with two dimeric species also observed in the solid phase. The presences of the two C1 and C2 forms together with the two dimeric species are supported by the IR and Raman bands between 1424 and 125 cm-1. Here, the properties for both forms of oxcarbazepine are compared and discussed.

Equilibrium isotope effects on noncovalent interactions in a supramolecular host-guest system.

PubMed

Mugridge, Jeffrey S; Bergman, Robert G; Raymond, Kenneth N

2012-02-01

The self-assembled supramolecular complex [Ga(4)L(6)](12-) (1; L = 1,5-bis[2,3-dihydroxybenzamido]naphthalene) can act as a molecular host in aqueous solution and bind cationic guest molecules to its highly charged exterior surface or within its hydrophobic interior cavity. The distinct internal cavity of host 1 modifies the physical properties and reactivity of bound guest molecules and can be used to catalyze a variety of chemical transformations. Noncovalent host-guest interactions in large part control guest binding, molecular recognition and the chemical reactivity of bound guests. Herein we examine equilibrium isotope effects (EIEs) on both exterior and interior guest binding to host 1 and use these effects to probe the details of noncovalent host-guest interactions. For both interior and exterior binding of a benzylphosphonium guest in aqueous solution, protiated guests are found to bind more strongly to host 1 (K(H)/K(D) > 1) and the preferred association of protiated guests is driven by enthalpy and opposed by entropy. Deuteration of guest methyl and benzyl C-H bonds results in a larger EIE than deuteration of guest aromatic C-H bonds. The observed EIEs can be well explained by considering changes in guest vibrational force constants and zero-point energies. DFT calculations further confirm the origins of these EIEs and suggest that changes in low-frequency guest C-H/D vibrational motions (bends, wags, etc.) are primarily responsible for the observed EIEs. © 2011 American Chemical Society

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

NASA Astrophysics Data System (ADS)

Watenphul, Anke; Schmidt, Christian; Jahn, Sandro

2014-02-01

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

Glycine glycinium picrate—Reinvestigation of the structure and vibrational spectra

NASA Astrophysics Data System (ADS)

Ghazaryan, V. V.; Fleck, M.; Petrosyan, A. M.

2011-01-01

The crystal of diglycine picrate (glycine glycinum picrate) has been obtained from an aqueous solution containing stoichiometric quantities of the components. The species crystallizes in the monoclinic system (space group P2 1/ c). The crystal structure was determined with high accuracy, IR and Raman spectra are discussed and compared with previous results, and the molecular structure is presented. It was shown that crystals of diglycine picrate obtained from the solution containing equimolar quantities may contain picric acid as impurity, which is the reason for the previously reported observation of second harmonic generation in this centrosymmetric crystal. With this example we want to point out the risk of misinterpretation of SHG signals in general.

Growing barium hexaferrite (BaFe{sub 12}O{sub 19}) thin films using chemical solution deposition

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

Budiawanti, Sri, E-mail: awanty77@yahoo.com; Faculty of Teacher Training and Education, Sebelas Maret University; Soegijono, Bambang

Barium hexaferrite (BaFe{sub 12}O{sub 19}, or simply known as BaM) thin films has been recognized as a potential candidate for microwave-based devices, magnetic recording media and data storage. To grow BaM thin films, chemical solution deposition is conducted using the aqueous solution of metal nitrates, which involves spin coatings on Si substrates. Furthermore, Thermal Gravimeter Analysis (TGA), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) are applied to evaluate the decomposition behavior, structure, morphology, and magnetic properties of BaM thin films. Additionally, the effects of number of layers variation are also investigated. Finally, magnetic properties analysismore » indicates the isotropic nature of the films.« less

Magneto-vibratory separation of glass and bronze granular mixtures immersed in a paramagnetic liquid.

PubMed

López-Alcaraz, P; Catherall, A T; Hill, R J A; Leaper, M C; Swift, Michael R; King, P J

2007-10-01

A fluid-immersed granular mixture may spontaneously separate when subjected to vertical vibration, separation occurring when the ratio of particle inertia to fluid drag is sufficiently different between the component species of the mixture. Here, we describe how fluid-driven separation is influenced by magneto-Archimedes buoyancy, the additional buoyancy force experienced by a body immersed in a paramagnetic fluid when a strong inhomogeneous magnetic field is applied. In our experiments glass and bronze mixtures immersed in paramagnetic aqueous solutions of MnCl2 have been subjected to sinusoidal vertical vibration. In the absence of a magnetic field the separation is similar to that observed when the interstitial fluid is water. However, at modest applied magnetic fields, magneto-Archimedes buoyancy may balance the inertia/fluid-drag separation mechanism, or it may dominate the separation process. We identify the vibratory and magnetic conditions for four granular configurations, each having distinctive granular convection. Abrupt transitions between these states occur at well-defined values of the magnetic and vibrational parameters. In order to gain insight into the dynamics of the separation process we use computer simulations based on solutions of the Navier-Stokes' equations. The simulations reproduce the experimental results revealing the important role of convection and gap formation in the stability of the different states.

Understanding THz spectra of aqueous solutions: glycine in light and heavy water.

PubMed

Sun, Jian; Niehues, Gudrun; Forbert, Harald; Decka, Dominique; Schwaab, Gerhard; Marx, Dominik; Havenith, Martina

2014-04-02

THz spectroscopy of aqueous solutions has been established as of recently to be a valuable and complementary experimental tool to provide direct insights into the solute-solvent coupling due to hydrogen-bond dynamics involving interfacial water. Despite much experimental progress, understanding THz spectra in terms of molecular motions, akin to mid-infrared spectra, still remains elusive. Here, using the osmoprotectant glycine as a showcase, we demonstrate how this can be achieved by combining THz absorption spectroscopy and ab initio molecular dynamics. The experimental THz spectrum is characterized by broad yet clearly discernible peaks. Based on substantial extensions of available mode-specific decomposition schemes, the experimental spectrum can be reproduced by theory and assigned on an essentially quantitative level. This joint effort reveals an unexpectedly clear picture of the individual contributions of molecular motion to the THz absorption spectrum in terms of distinct modes stemming from intramolecular vibrations, rigid-body-like hindered rotational and translational motion, and specific couplings to interfacial water molecules. The assignment is confirmed by the peak shifts observed in the THz spectrum of deuterated glycine in heavy water, which allow us to separate the distinct modes experimentally.

The influence of ionic strength on carbonate-based spectroscopic barometry for aqueous fluids: an in-situ Raman study on Na2CO3-NaCl solutions

PubMed Central

Wu, Jia; Wang, Shixia; Zheng, Haifei

2016-01-01

The Raman wavenumber of the symmetric stretching vibration of carbonate ion (ν1-CO32−) was measured in three aqueous solutions containing 2.0 mol·L−1 Na2CO3 and 0.20, 0.42, or 0.92 mol·L−1 NaCl, respectively, from 122 to 1538 MPa at 22 °C using a moissanite anvil cell. The ν1 Raman signal linearly shifted to higher wavenumbers with increasing pressure. Most importantly, the slope of ν1-CO32− Raman frequency shift (∂ν1/∂P)I was independent of NaCl concentration. Moreover, elevated ionic strength was found to shift the apparent outline of the carbonate peak toward low wavenumbers, possibly by increasing the proportion of the contact ion pair NaCO3−. Further investigations revealed no cross-interaction between the pressure effect and the ionic strength effect on the Raman spectra, possibly because the distribution of different ion-pair species in the carbonate equilibrium was largely pressure-independent. These results suggested that the ionic strength should be incorporated as an additional constraint for measuring the internal pressure of various solution-based systems. Combining the ν1-CO32− Raman frequency slope with the pressure herein with the values for the temperature or the ionic strength dependencies determined from previous studies, we developed an empirical equation that can be used to estimate the pressure of carbonate-bearing aqueous solutions. PMID:27982064

Alumino-silicate speciation in aqueous fluids at deep crustal conditions

NASA Astrophysics Data System (ADS)

Mookherjee, M.; Keppler, H.; Manning, C. E.

2014-12-01

Alumina and silica are major oxides in most crustal rocks. While SiO2 is quite soluble in aqueous fluids at metamorphic conditions, behavior of Al2O3 in crustal metamorphic fluids has been poorly understood. It is known that alumina is dramatically less soluble in aqueous fluids and hence it is difficult to explain the common occurrence of quartz with aluminous minerals in metamorphic veins. In order to understand this complex behavior of alumina, we investigated aluminum speciation in aqueous fluids in equilibrium with corundum using in situ Raman spectroscopy in hydrothermal diamond anvil cells to 20 kbar and 1000 oC. In order to better understand the spectral features of the aqueous fluids, we used first principles simulations based on density functional theory to calculate and predict the energetics and vibrational spectra for various aluminum species that are likely to be present in aqueous solutions. The Raman spectra of pure water in equilibrium with Al2O3 are devoid of any characteristic spectral features. In contrast, aqueous fluids with KOH solution in equilibrium with Al2O3 show a sharp band at ~620 cm-1 which could be attributed to the [Al(OH)4]1- species. The band grows in intensity with temperature along an isochore. In the limited pressure, temperature and density explored in the present study, we do not find any evidence for the polymerization of the [Al(OH)4]1- species to dimers [(OH)2-Al-O2-Al(OH)2]2- or [(OH)3-Al-O-Al(OH)3]2-. This is likely due to the relatively low concentration of Al in the solutions and does not rule out significant polymerization at higher pressures and temperatures. We are also investigating the effect of SiO2 on the solubility of Al2O3 and the relative energetics of formation of pure alumina dimer [(OH)3-Al-O-Al(OH)3]2- vs. the aluminosilicate dimers, [(OH)3-Al-O-Si(OH)3]2- at deep crustal conditions. Acknowledgement- MM is supported by the US National Science Foundation grant (EAR-1250477).

Development of a Scaled Quantum Mechanical Force Field for Peptides in Aqueous Solution

DTIC Science & Technology

1996-03-01

differ. Raman and IR techniques are complimentary which helps in assignment of observed vibrational modes. As described in beginning organic ...1588 I NH, .i.sor(98) 2076 2100 24 CH3 55(95) 2125 2207 82 CH3 as’ (56), CH3 as’ (43) 2235 2253 18 CH3 as’(55), CH3 as’(41) 2888 COff .(100) 3155 NH...Application of self- consistent-field ab initio calculations to organic molecules I. Equilibrium struc- ture and force constants of hydrocarbons

Modeling the antisymmetric and symmetric stretching vibrational modes of aqueous carboxylate anions

NASA Astrophysics Data System (ADS)

Sutton, Catherine C. R.; Franks, George V.; da Silva, Gabriel

2015-01-01

The infrared spectra of six aqueous carboxylate anions have been calculated at the M05-2X/cc-pVTZ level of theory with the SMD solvent model, and validated against experimental data from the literature over the region of 1700 cm-1 to 1250 cm-1; this region corresponds to the stretching modes of the carboxylate group, and is often interrogated when probing bonding of carboxylates to other species and surfaces. The anions studied here were formate, acetate, oxalate, succinate, glutarate and citrate. For the lowest energy conformer of each anion, the carboxylate moiety antisymmetric stretching peak was predicted with a mean signed error of only 4 cm-1 using the SMD solvent model, while the symmetric peak was slightly overestimated. Performing calculations in vacuum and scaling was found to generally over-predict the antisymmetric vibrational frequencies and under predict the symmetric peak. Different conformers of the same anion were found to have only slightly different spectra in the studied region and the inclusion of explicit water molecules was not found to significantly change the calculated spectra when the implicit solvent model is used. Overall, the use of density functional theory in conjunction with an implicit solvent model was found to result in infra-red spectra that are the best reproduction of the features found experimentally for the aqueous carboxylate ions in the important 1700 cm-1 to 1250 cm-1 region. The development of validated model chemistries for simulating the stretching modes of aqueous carboxylate ions will be valuable for future studies that investigate how carboxylate anions complex with multivalent metal cations and related species in solution.

Hybrid CARS for Non-Invasive Blood Glucose Monitoring

NASA Astrophysics Data System (ADS)

Wang, Xi; Pestov, Dmitry; Zhang, Aihua; Murawski, Robert; Sokolov, Alexei; Welch, George; Laane, Jaan; Scully, Marlan

2007-10-01

We develop a spectroscopy technique that combines the advantages of both the frequency-resolved coherent anti-Stokes Raman scattering (CARS) and the time-resolved CARS. We use broadband preparation pulses to get an instantaneous coherent excitation of multiplex molecular vibration levels and subsequent optically shaped time-delayed narrowband probing pulse to detect these vibrations. This technique can suppress the nonresonant background and retrieve the molecular fingerprint signal efficiently and rapidly. We employ this technique to glucose detection, the final goal of which is accurate, non-invasive (i.e. painless) and continuous monitoring of blood glucose concentration in the Diabetes diagnosis to replace the current glucose measurement process, which requires painful fingerpricks and therefore cannot be performed more than a few times a day. We have gotten the CARS spectra of glucose aqueous solution down to 2 mM.

Volume properties and spectroscopy: A terahertz Raman investigation of hen egg white lysozyme

NASA Astrophysics Data System (ADS)

Sassi, Paola; Perticaroli, Stefania; Comez, Lucia; Giugliarelli, Alessandra; Paolantoni, Marco; Fioretto, Daniele; Morresi, Assunta

2013-12-01

The low frequency depolarized Raman spectra of 100 mg/ml aqueous solutions of hen egg white lysozyme (HEWL) have been collected in the 25-85 °C range. Short and long exposures to high temperatures have been used to modulate the competition between the thermally induced reversible and irreversible denaturation processes. A peculiar temperature evolution of spectra is evidenced under prolonged exposure of the protein solution at temperatures higher than 65 °C. This result is connected to the self-assembling of polypeptide chains and testifies the sensitivity of the technique to the properties of both protein molecule and its surrounding. Solvent free spectra have been obtained after subtraction of elastic and solvent components and assigned to a genuine vibrational contribution of hydrated HEWL. A straight similarity is observed between the solvent-free THz Raman feature and the vibrational density of states as obtained by molecular dynamics simulations; according to this, we verify the relation between this spectroscopic observable and the effective protein volume, and distinguish the properties of this latter respect to those of the hydration shell in the pre-melting region.

Magnetite Nanoparticles Coated with Rifampicin and Chlortetracycline for Drug Delivery Applications

NASA Astrophysics Data System (ADS)

Nǎdejde, Claudia; Ciurlicǎ, Ecaterina Foca-nici; Creangǎ, Dorina; Cârlescu, Aurelian; Bǎdescu, Vasile

2010-12-01

Four types of biocompatible magnetic fluids based on superparamagnetic nanoparticles with Fe3O4 cores were functionalized with antibiotics (rifampicin or chlortetracycline) as potential candidates for in vivo biomedical applications, such as magnetically controlled drug delivery. The synthesis consisted in coprecipitation of iron oxide in basic, as well as in acid medium, followed by the dispersion of the resulted magnetite nanoparticles in aqueous solution containing the antibiotic. The chosen method to prepare the magnetite-core/drug-shell systems avoided intermediate organic coating of the magnetic nanoparticles. Comparative analysis of the rheological features of the aqueous magnetic fluid samples was performed. The structural features of the coated magnetic particles were investigated by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). Good crystallinity and adequate stability in time were evidenced. Drug delivery curves were spectrophotometrically provided.

Synthesis, characterisation of polyaniline-Fe3O4 magnetic nanocomposite and its application for removal of an acid violet 19 dye

NASA Astrophysics Data System (ADS)

Patil, Manohar R.; Khairnar, Subhash D.; Shrivastava, V. S.

2016-04-01

The present work deals with the development of a new method for the removal of dyes from an aqueous solution using polyaniline (PANI)-Fe3O4 magnetic nanocomposite. It is synthesised in situ through self-polymerisation of monomer aniline. Photocatalytic degradation studies were carried out for cationic acid violet 19 (acid fuchsine) dye using PANI-Fe3O4 nanocomposite in aqueous solution. Different parameters like catalyst dose, contact time and pH have been studied to optimise reaction condition. The optimum conditions for the removal of the dye are initial concentration 20 mg/l, adsorbent dose 6 gm/l, pH 7. The EDS technique gives elemental composition of synthesised PANI-Fe3O4. The SEM and XRD studies were carried for morphological feature characteristics of PANI-Fe3O4 nanocomposite. The VSM (vibrating sample magnetometer) gives magnetic property of PANI-Fe3O4 nanocomposite; also FT-IR analysis gives characteristics frequency of synthesised PANI-Fe3O4. Besides the above studies kinetic study has also been carried out.

Revisiting the Aqueous Solutions of Dimethyl Sulfoxide by Spectroscopy in the Mid- and Near-Infrared: Experiments and Car-Parrinello Simulations.

PubMed

Wallace, Victoria M; Dhumal, Nilesh R; Zehentbauer, Florian M; Kim, Hyung J; Kiefer, Johannes

2015-11-19

The infrared and near-infrared spectra of the aqueous solutions of dimethyl sulfoxide are revisited. Experimental and computational vibrational spectra are analyzed and compared. The latter are determined as the Fourier transformation of the velocity autocorrelation function of data obtained from Car-Parrinello molecular dynamics simulations. The experimental absorption spectra are deconvolved, and the excess spectra are determined. The two-dimensional excess contour plot provides a means of visualizing and identifying spectral regions and concentration ranges exhibiting nonideal behavior. In the binary mixtures, the analysis of the SO stretching band provides a semiquantitative picture of the formation and dissociation of hydrogen-bonded DMSO-water complexes. A maximum concentration of these clusters is found in the equimolar mixture. At high DMSO concentration, the formation of rather stable 3DMSO:1water complexes is suggested. The formation of 1DMSO:2water clusters, in which the water oxygen atoms interact with the sulfoxide methyl groups, is proposed as a possible reason for the marked depression of the freezing temperature at the eutectic point.

The synthesis of Cu/Fe/Fe3O4 catalyst through the aqueous solution ball milling method assisted by high-frequency electromagnetic field

NASA Astrophysics Data System (ADS)

Yingzhe, Zhang; Yuxing, He; Qingdong, Qin; Fuchun, Wang; Wankun, Wang; Yongmei, Luo

2018-06-01

In this paper, nano-magnetic Cu/Fe/Fe3O4 catalyst was prepared by a new aqueous solution ball milling method assisted by high-frequency electromagnetic field at room temperature. The products were characterized by means of X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and vibrating sample magnetometer (VSM). Microwave induced catalytic degradation of methylene blue (MB) was carried out in the presence of Cu/Fe/Fe3O4. The concentration of methylene blue was determined by UV-Vis spectrophotometry. The solid catalyst showed high catalytic activity of degrade MB and considerable saturation magnetization, lower remanence and coercivity. It indicate that the catalyst can be effectively separated for reuse by simply applying an external magnetic field and it can greatly promote their potential industrial application to eliminate organic pollutants from waste-water. Finally, we found that it is the non-thermal effect of microwave that activated the catalytic activity of Cu/Fe/Fe3O4 to degrade MB.

On the Behavior of Physical Parameters of Aqueous Solutions Affected by the Inerton Field of TESLAR® Technology

NASA Astrophysics Data System (ADS)

Krasnoholovets, Volodymyr; Skliarenko, Sergiy; Strokach, Olexander

We present studies of the behavior of the permittivity of such liquid systems as pure distilled water, alcohol and 50%-aqueous solutions of alcohol as affected by the inerton field generated by a special signal generator contained within a wrist-watch or bracelet made by so-called Teslar® technology. It has been found that the changes are in fact significant. The method employed has allowed us to fix the value of frequency of the field generated by the Teslar® chip. The frequency has been determined to be approximately 8 Hz. The phenomenological consideration and submicroscopic foundations of a significant increase of the permittivity are studied, taking into account an additional interaction, namely, the mass interaction between polar water molecules, which is caused by the inerton field of the Teslar® chip. This is one more proof of Krasnoholovets' concept regarding the existence of a substructure of the matter waves of moving/vibrating entities, i.e. the inerton field, which has been predicted in a series of his previous works.

Use of amino acid-based polymeric material for isolation of a protein from poison

NASA Astrophysics Data System (ADS)

Erol, Kadir; Köse, Kazım; Güngüneş, Hakan; Köse, Dursun Ali

2017-02-01

Melittin is a small protein with 126 amino acid residues which exists in the bee and snake venom. In this study, the Fe(II)-Ni(II) double-salt incorporated poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid), poly(HEMA-MAsp), magnetic microparticles were synthesized for the separation of melittin. Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer and Mossbauer spectroscopy techniques were used for the characterization. The melittin adsorption capacity of magnetic microparticles in aqueous solution were identified as 69.60 mg/g, whereas that in real be venom solution was 46.80 mg/g microparticle. The adsorption-desorption cycle was repeated 5 times and no significant decrease were observed in the adsorption capacity.

Eco-friendly synthesis of cuprous oxide (Cu2O) nanoparticles and improvement of their solar photocatalytic activities

NASA Astrophysics Data System (ADS)

Kerour, A.; Boudjadar, S.; Bourzami, R.; Allouche, B.

2018-07-01

In this work, we have synthesized cuprous oxide (Cu2O) nanoparticles with octahedral and spherical like shapes by an ecofriendly, simple and coast effective method, by using the aqueous extract of Aloe vera and copper sulfate as solvent and precursor respectively. The effect of Aloe vera aqueous extract concentration on the morphological, structural and optical properties of as synthesized nanoparticles was studied by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform (FT-IR) spectroscopy and UV-visible diffuse reflectance. The SEM images showing octahedral and spherical agglomeration of nanoparticles. The cubic structure of Cu2O was confirmed by XRD analysis, the crystallites size depends to the concentration of Aloe vera aqueous extract with an average size ranged between 24 and 61 nm. The FT-IR vibration measurements valid the presence of pure Cu2O in the samples. The UV-visible spectra show that the prepared cuprous oxide (Cu2O) has a gap energy estimated from 2.5 to 2.62 eV. The photocatalytic activities of the as-prepared material were highly improvement by the fast degradation of methylene blue in aqueous solution at room temperature under solar simulator irradiation.

Structural, vibrational and thermal studies of a new nonlinear optical material: L-asparagine-L-tartaric acid.

PubMed

Moovendaran, K; Srinivasan, Bikshandarkoil R; Kalyana Sundar, J; Martin Britto Dhas, S A; Natarajan, S

2012-06-15

Crystals of a new nonlinear optical (NLO) material, viz., L-asparagine-L-tartaric acid (LALT) (1) were grown by slow evaporation of an aqueous solution containing equimolar concentrations of L-asparagine and L-tartaric acid. The structure of the title compound which crystallizes in the non-centrosymmetric monoclinic space group P2(1) consists of a molecule of L-asparagine and a molecule of free l-tartaric acid both of which are interlinked by three varieties of H-bonding interactions namely O-H···O, N-H···O and C-H···O. The UV-Vis-NIR spectrum of 1 reveals its transparent nature while the vibrational spectra confirm the presence of the functional groups in 1. The thermal stability and second harmonic generation (SHG) conversion efficiency of 1 were investigated. Copyright © 2012 Elsevier B.V. All rights reserved.

pH-Dependent reversible crystal transformation of 1-carboxymethyl-1-methyl-pyrrolidinium bromides and their spectroscopic fingerprint

NASA Astrophysics Data System (ADS)

Tong, Ya-yan; Zhang, Heng; Chang, Liang-liang; Xuan, Xiao-peng

2018-03-01

In this work, two 1-carboxymethyl-1-methyl-pyrrolidinium bromides (N-methylpyrrolidine betaine hydrobromides) with the stoichiometry of betaine:hydrobromic acid as 1:1 and 2:1, denoted as CMPRHBr-I and CMPRHBr-II, respectively, were prepared and crystallographically determined. The large difference in these two structures is the type of hydrogen bonds, resulting in the different thermal stability. A strong Osbnd H ⋯ Br hydrogen bond was observed in CMPRHBr-I, whereas O ⋯ H ⋯ O hydrogen bond in CMPRHBr-II. Both these two crystals can mutually transform by changing the pH value of the aqueous solution. Vibrational spectroscopic studies shows that these two structures can be easily distinguished by the characteristic bands such as νCdbnd O stretching vibration and the D-type bands. Our studies indicate that it should be cautious of the structural change as this type of organic salts was purified and recrystallized.

Removal of cadmium(II) ions from aqueous solution using Ni (15 wt.%)-doped α-Fe2O3 nanocrystals: equilibrium, thermodynamic, and kinetic studies.

PubMed

OuldM'hamed, Mohamed; Khezami, L; Alshammari, Abdulrahman G; Ould-Mame, S M; Ghiloufi, I; Lemine, O M

2015-01-01

The present publication investigates the performance of nanocrystalline Ni (15 wt.%)-doped α-Fe2O3 as an effective nanomaterial for the removal of Cd(II) ions from aqueous solutions. The nanocrystalline Ni-doped α-Fe2O3 powders were prepared by mechanical alloying, and characterized by X-ray diffraction and a vibrating sample magnetometer. Batch-mode experiments were realized to determine the adsorption equilibrium, kinetics, and thermodynamic parameters of toxic heavy metal ions by Ni (15 wt.%)-doped α-Fe2O3. The adsorption isotherms data were found to be in good agreement with the Langmuir model. The adsorption capacity of Cd(II) ion reached a maximum value of about 90.91 mg g(-1) at 328 K and pH 7. The adsorption process kinetics was found to comply with pseudo-second-order rate law. Thermodynamic parameters related to the adsorption reaction, free energy change, enthalpy change and entropy change, were evaluated. The found values of free energy and enthalpy revealed a spontaneous endothermic adsorption-process. Moreover, the positive entropy suggests an increase of randomness during the process of heavy metal removal at the adsorbent-solution interface.

Effect of molecular environment on the vibrational dynamics of pyrimidine bases as analysed by NIS, optical spectroscopy and quantum mechanical force fields

NASA Astrophysics Data System (ADS)

Ghomi, M.; Aamouche, A.; Cadioli, B.; Berthier, G.; Grajcar, L.; Baron, M. H.

1997-06-01

A complete set of vibrational spectra, obtained from several spectroscopic techniques, i.e. neutron inelastic scattering (NIS), Raman scattering and infrared absorption (IR), has been used in order to assign the vibrational modes of pyrimidine bases (uracil, thymine, cytosine) and their N-deuterated species. The spectra of solid and aqueous samples allowed us to analyse the effects of hydrogen bonding in crystal and in solution. In a first step, to assign the observed vibrational modes, we have resorted to harmonic quantum mechanical force field, calculated at SCF + MP2 level using double-zeta 6-31G and D95V basis sets with non-standard exponents for d-orbital polarisation functions. In order to improve the agreement between the experimental results obtained in condensed phases and the calculated ones based on isolated molecules, the molecular force field has been scaled. In a second step, to estimate the effect of intermolecular interactions on the vibrational dynamics of pyrimidine bases, we have undertaken additional calculations with the density functional theory (DFT) method using B3LYP functionals and polarised 6-31G basis sets. Two theoretical models have been considered: 1. a uracil embedded in a dielectric continuum ( ɛ = 78), and 2. a uracil H-bonded to two water molecules (through N1 and N3 atoms).

Hydrothermal synthesis of PEDOT/rGO composite for supercapacitor applications

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Rafat, M.

2018-01-01

In this study, PEDOT/rGO composite has been successfully synthesized using hydrothermal method. Precursor solution of EDOT monomer was mixed with a predetermined solution of graphene oxide (GO). The resultant mixture was then hydrothermally treated. Surface morphology, crystal structure vibrational response and thermal stability have been studied using standard characterization techniques: field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and thermo-gravimetric analysis. The observed results confirm that the required composite of PEDOT/rGO has indeed been synthesized. Electrochemical properties of the synthesized product were studied in 6 M KOH aqueous solution, using characterization techniques such as: cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge measurements. The results show a high value of specific capacitance (102.8 F g-1) at 10 mV s-1, indicating that the composite can be profitably used for energy storage devices.

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth.

PubMed

Jarisz, Tasha A; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K

2018-06-14

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth

NASA Astrophysics Data System (ADS)

Jarisz, Tasha A.; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K.

2018-06-01

Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

Physical and chemical interactions at the interface between atmospheric pressure plasmas and aqueous solutions

NASA Astrophysics Data System (ADS)

Lindsay, Alexander; Byrns, Brandon; Knappe, Detlef; Graves, David; Shannon, Steven

2014-10-01

Transport and reactions of charged species, neutrals, and photons at the interface between plasmas and liquids must be better quantified. The work presented here combines theoretical and experimental investigations of conditions in the gas and liquid phases in proximity to the interface for various discharges. OES is used to determine rotational and vibrational temperatures of OH, NO, and N2+; the relationship between these temperatures that characterize the distribution of internal energy states and gas and electron kinetic temperatures is considered. The deviation of OH rotational states from equilibrium under high humidity conditions is also presented. In contradiction with findings of other groups, high energy rotational states appear to become underpopulated with increasing humidity. In the aqueous phase, concentrations of longer-lived species such as nitrate, nitrite, hydrogen peroxide, and ozone are determined using ion chromatography and colorimetric methods. Spin-traps and electron paramagnetic resonance (EPR) are investigated for characterization of short-lived aqueous radicals like OH, O2-, NO, and ONOO-. Finally, experimental results are compared to a numerical model which couples transport and reactions within and between the bulk gas and liquid phases.

Optical and vibrational properties of PbSe nanoparticles synthesized in clinoptilolite

NASA Astrophysics Data System (ADS)

Flores-Valenzuela, J.; Cortez-Valadez, M.; Ramírez-Bon, R.; Arizpe-Chavez, H.; Román-Zamorano, J. F.; Flores-Acosta, M.

2015-08-01

In this work, the optical and vibrational properties of composites based on PbSe semiconductor immersed in a zeolite matrix are reported. The natural zeolite, (clinoptilolite) was used as the host material of PbSe nanoparticles. The method for obtaining these particles is also reported here, which is based on ion exchange processes inside the natural zeolite in alkaline aqueous solution that contains the precursor ions Pb2+ and Se2-. The process of synthesis was conducted temperature, volume, concentration and reaction time of the precursors. The samples were studied by powder X-ray diffraction, TEM (transmission electron microscopy), diffuse reflectance and Raman spectroscopy. The experimental results demonstrate that with this method, the particles with nanometric PbSe sizes were synthesized in the zeolite matrix. Vibrational Raman bands at low wave numbers were detected in these particles by the presence of a shoulder located at 135 cm-1 and a band at around 149 cm-1. The vibrational calculations for small clusters of PbSe at LSDA (Local Spin Density Approximation) level combined with the basis set LANDL2DZ (Los Alamos National Laboratory 2 double ζ), were considered through DFT (Density Functionl Theory). The "breathing" Raman modes located at 119-152 cm-1 were detected for this level of theory.

On the vibrational behavior of single- and double-walled carbon nanotubes under the physical adsorption of biomolecules in the aqueous environment: a molecular dynamics study.

PubMed

Ajori, S; Ansari, R; Darvizeh, M

2016-03-01

The adsorption of biomolecules on the walls of carbon nanotubes (CNTs) in an aqueous environment is of great importance in the field of nanobiotechnology. In this study, molecular dynamics (MD) simulations were performed to understand the mechanical vibrational behavior of single- and double-walled carbon nanotubes (SWCNTs and DWCNTs) under the physical adsorption of four important biomolecules (L-alanine, guanine, thymine, and uracil) in vacuum and an aqueous environment. It was observed that the natural frequencies of these CNTs in vacuum reduce under the physical adsorption of biomolecules. In the aqueous environment, the natural frequency of each pure CNT decreased as compared to its natural frequency in vacuum. It was also found that the frequency shift for functionalized CNTs as compared to pure CNTs in the aqueous environment was dependent on the radius and the number of walls of the CNT, and could be positive or negative.

Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

PubMed

Singh, Gurpreet; Mohanty, B P; Saini, G S S

2016-02-15

Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide. Copyright © 2015 Elsevier B.V. All rights reserved.

Atmospheric pressure laser desorption/ionization using a 6-7 µm-band mid-infrared tunable laser and liquid water matrix.

PubMed

Hiraguchi, Ryuji; Hazama, Hisanao; Masuda, Katsuyoshi; Awazu, Kunio

2015-01-01

Due to the characteristic absorption peaks in the IR region, various molecules can be used as a matrix for infrared matrix-assisted laser desorption/ionization (IR-MALDI). Especially in the 6-7 µm-band IR region, solvents used as the mobile phase for liquid chromatography have absorption peaks that correspond to their functional groups, such as O-H, C=O, and CH3. Additionally, atmospheric pressure (AP) IR-MALDI, which is applicable to liquid-state samples, is a promising technique to directly analyze untreated samples. Herein we perform AP-IR-MALDI mass spectrometry of a peptide, angiotensin II, using a mid-IR tunable laser with a tunable wavelength range of 5.50-10.00 µm and several different matrices. The wavelength dependences of the ion signal intensity of [M + H](+) of the peptide are measured using a conventional solid matrix, α-cyano-4-hydroxycinnamic acid (CHCA) and a liquid matrix composed of CHCA and 3-aminoquinoline. Other than the O-H stretching and bending vibration modes, the characteristic absorption peaks are useful for AP-IR-MALDI. Peptide ions are also observed from an aqueous solution of the peptide without an additional matrix, and the highest peak intensity of [M + H](+) is at 6.00 µm, which is somewhat shorter than the absorption peak wavelength of liquid water corresponding to the O-H bending vibration mode. Moreover, long-lasting and stable ion signals are obtained from the aqueous solution. AP-IR-MALDI using a 6-7 µm-band IR tunable laser and solvents as the matrix may provide a novel on-line interface between liquid chromatography and mass spectrometry. Copyright © 2015 John Wiley & Sons, Ltd.

Deuterium kinetic isotope effects on the dissociation of a protein-fatty acid complex in the gas phase.

PubMed

Liu, Lan; Michelsen, Klaus; Kitova, Elena N; Schnier, Paul D; Brown, Alex; Klassen, John S

2012-04-04

Deuterium kinetic isotope effects (KIEs) are reported for the first time for the dissociation of a protein-ligand complex in the gas phase. Temperature-dependent rate constants were measured for the loss of neutral ligand from the deprotonated ions of the 1:1 complex of bovine β-lactoglobulin (Lg) and palmitic acid (PA), (Lg + PA)(n-) → Lg(n-) + PA, at the 6- and 7- charge states. At 25 °C, partial or complete deuteration of the acyl chain of PA results in a measurable inverse KIE for both charge states. The magnitude of the KIEs is temperature dependent, and Arrhenius analysis of the rate constants reveals that deuteration of PA results in a decrease in activation energy. In contrast, there is no measurable deuterium KIE for the dissociation of the (Lg + PA) complex in aqueous solution at pH 8. Deuterium KIEs were calculated using conventional transition-state theory with an assumption of a late dissociative transition state (TS), in which the ligand is free of the binding pocket. The vibrational frequencies of deuterated and non-deuterated PA in the gas phase and in various solvents (n-hexane, 1-chlorohexane, acetone, and water) were established computationally. The KIEs calculated from the corresponding differences in zero-point energies account qualitatively for the observation of an inverse KIE but do not account for the magnitude of the KIEs nor their temperature dependence. It is proposed that the dissociation of the (Lg + PA) complex in aqueous solution also proceeds through a late TS in which the acyl chain is extensively hydrated such that there is no significant differential change in the vibrational frequencies along the reaction coordinate and, consequently, no significant KIE.

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.

Picosecond dynamics of photoexcited DNO-bound myoglobin probed by femtosecond vibrational spectroscopy.

PubMed

Lee, Taegon; Hwang, Sungu; Lim, Manho

2015-02-05

Like nitric oxide (NO), nitroxyl (HNO), a reduced form of NO, plays many biologically important roles including neurological function and vascular regulation. Although HNO is unstable in aqueous solution, it is exceptionally stable on binding to ferrous myoglobin (Mb) to form MbHNO. Various experimental and theoretical investigations has been carried out to unveil the structure of the active site and binding characteristics of MbHNO that can explain its functioning mechanism and the origin of its unusual stability. However, the binding dynamics of HNO to Mb, as well as the photochemical and photophysical processes associated with binding, have not been fully established. Herein, femtosecond vibrational spectroscopy was used to probe the photoexcitation dynamics of excited MbDNO in D2O solution at 294 K with a 575 nm pulse. Time-resolved spectra were described by three vibrational bands near 1380 cm(-1), in the expected N-O stretching (νN-O) mode of MbDNO, and all three bands showed instantaneous bleach that decays on a picosecond time scale. The three bands were assigned based on isotope shifts upon (15)N substitution and ab initio calculation of the vibrational frequency on a DNO-bound model heme. These three bands likely arise from Fermi interactions between the strong νN-O mode and the weak overtone and combination modes of the N atom-related modes. The immediate appearance of the bleach in these bands and the picosecond decay of the bleach indicate that most of the photoexcited MbDNO undergoes picosecond geminate rebinding (GR) of DNO to Mb subsequent to its immediate deligation. Ultrafast and efficient GR of DNO likely arises from the bonding structure of the ligand and high reactivity between DNO and Mb.

A Comparative Study of [CaEDTA](2-) and [MgEDTA](2-): Structural and Dynamical Insights from Quantum Mechanical Charge Field Molecular Dynamics.

PubMed

Tirler, Andreas O; Hofer, Thomas S

2015-07-09

Structure and dynamics of [MgEDTA](2-) and [CaEDTA](2-) complexes in aqueous solution have been investigated via quantum mechanical/molecular mechanical (QM/MM) simulations. While for the first a 6-fold octahedral complex has been observed, the presence of an additional coordinating water ligand has been observed in the latter case. Because of rapidly exchanging water molecules, this 7-fold coordination complex was found to form pentagonal bipyramidal as well as capped trigonal prismatic configurations along the simulation interchanging on the picosecond time scale. Also in the case of [MgEDTA](2-) a trigonal prismatic configuration has been observed for a very short time period of approximately 1 ps. This work reports for the first time the presence of trigonal prismatic structures observed in the coordination sphere of [MgEDTA](2-) and [CaEDTA](2-) complexes in aqueous solution. In addition to the detailed characterization of structure and dynamics of the systems, the prediction of the associated infrared spectra indicates that the ion-water vibrational mode found at approximately 250 cm(-1) provides a distinctive measure to experimentally detect the presence of the coordinating water molecule via low-frequency IR setups.

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.

Elaboration of nano titania-magnetic reduced graphene oxide for degradation of tartrazine dye in aqueous solution

NASA Astrophysics Data System (ADS)

Nada, Amr A.; Tantawy, Hesham R.; Elsayed, Mohamed A.; Bechelany, Mikhael; Elmowafy, Mohamed E.

2018-04-01

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (UV-vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).

Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites.

PubMed

Areerob, Yonrapach; Cho, Ju Yong; Jang, Won Kweon; Oh, Won-Chun

2018-03-01

Fe 3 O 4 -graphene/ZnO@mesoporous-SiO 2 (MGZ@SiO 2 ) nanocomposites was synthesized via a simple one pot hydrothermal method. The as-obtained samples were investigated using various techniques, as follows: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area (BET) vibrating sample magnetometer (VSM), among others. The sonocatalytic activities of the catalysts were tested according to the oxidation for the removal of methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultrasonic irradiation. The optimal conditions including the irradiation time, pH, dye concentration, catalyst dosage, and ultrasonic intensity are 60min, 11, 50mg/L, 1.00g/L, and 40W/m 2 , respectively. The MGZ@SiO 2 showed the higher enhanced sonocatalytic degradation from among the three dyes; furthermore, the sonocatalytic-degradation mechanism is discussed. This study shows that the MGZ@SiO 2 can be applied asa novel-design catalyst for the removal of organic pollutants from aqueous solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Theoretical study on the dimerization of Si(OH) 4 in aqueous solution and its dependence on temperature and dielectric constant

NASA Astrophysics Data System (ADS)

Tossell, J. A.

2005-01-01

Energetics for the condensation dimerization reaction of monosilicic acid: 2Si(⇒SiOH+HO have been calculated quantum mechanically, in gas-phase and aqueous solution, over a range of temperatures and dielectric constants. The calculated gas phase energy, E g, for this reaction is -6.6 kcal/mol at the very accurate composite G2 level, but the vibrational, rotational and translational contributions to the free energy in the gas-phase, ΔG VRT, sum to + 2.5 kcal/mol and the hydration free energy contribution calculated with a polarizable continuum model, ΔΔG COSMO, for a dielectric constant of 78.5, is about + 6.2 kcal/mol. Thus, the free energy change for the reaction in aqueous solution at ambient conditions is about + 2.1 kcal/mol and the equilibrium constant is ˜10 -1.5, in reasonable agreement with experiment. As T increases, ΔG VRT increases slowly. As the dielectric constant decreases (for example, under high T and P conditions in the supercritical region), ΔΔG COSMO decreases substantially. Thus, at elevated T and P, if the effective dielectric constant of the aqueous fluid is 10 or less, the reaction becomes much more favorable, consistent with recent experimental observations. The PΔV contribution to the enthalpy is also considered, but cannot be accurately determined. We have also calculated 29Si-NMR shieldings and Raman frequencies for Si(OH) 4, Si 2O 7H 6 and some other oligomeric silicates. We correctly reproduce the separation of monomer and dimer peaks observed in the 29Si-NMR spectrra at ambient T and P. The Raman spectral data are somewhat ambiguous, and the new peaks seen at high T and P could arise either from the dimer or from a 3-ring trimer, which is calculated to be highly stabilized entropically at high T.

Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

NASA Astrophysics Data System (ADS)

Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G.

2015-06-01

Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm-1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ˜0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters.

Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

PubMed Central

Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G.

2015-01-01

Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm−1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ∼0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters. PMID:26049458

The geometric structures, vibrational frequencies and redox properties of the actinyl coordination complexes ([AnO2(L)n](m); An = U, Pu, Np; L = H2O, Cl-, CO3(2-), CH3CO2(-), OH-) in aqueous solution, studied by density functional theory methods.

PubMed

Austin, Jonathan P; Sundararajan, Mahesh; Vincent, Mark A; Hillier, Ian H

2009-08-14

The geometric and electronic structures of the aqua, chloro, acetato, hydroxo and carbonato complexes of U, Np and Pu in both their (VI) and (V) oxidation states, and in an aqueous environment, have been studied using density functional theory methods. We have obtained micro-solvated structures derived from molecular dynamics simulations and included the bulk solvent using a continuum model. We find that two different hydrogen bonding patterns involving the axial actinyl oxygen atoms are sometimes possible, and may give rise to different An-O bond lengths and vibrational frequencies. These alternative structures are reflected in the experimental An-O bond lengths of the aqua and carbonato complexes. The variation of the redox potential of the uranyl complexes with the different ligands has been studied using both BP86 and B3LYP functionals. The relative values for the four uranium complexes having anionic ligands are in surprisingly good agreement with experiment, although the absolute values are in error by approximately 1 eV. The absolute error for the aqua species is much less, leading to an incorrect order of the redox potentials of the aqua and chloro species.

Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds

NASA Technical Reports Server (NTRS)

Atwater, James E.; Akse, James R.; Jovanovic, Goran N.; Wheeler, Richard R Jr; Sornchamni, Thana

2003-01-01

Porous metallic cobalt spheres have been prepared as high temperature capable media for employment in gradient magnetically assisted fluidization and filtration technologies. Cobalt impregnated alginate beads are first formed by extrusion of an aqueous suspension of Co3O4 into a Co(II) chloride solution. The organic polymer is thermally decomposed yielding cobalt oxide spheres, followed by reduction to the metallic state, and densification. Cobalt beads have been produced with porosities ranging between 10 and 50%, depending upon sintering conditions. The product media have been characterized by scanning electron microscopy (SEM), nitrogen adsorption porosimetry, and vibrating sample magnetometry. c2003 Elsevier Science Ltd. All rights reserved.

Comprehensive Experimental and Computational Spectroscopic Study of Hexacyanoferrate Complexes in Water: From Infrared to X-ray Wavelengths.

PubMed

Ross, Matthew; Andersen, Amity; Fox, Zachary W; Zhang, Yu; Hong, Kiryong; Lee, Jae-Hyuk; Cordones, Amy; March, Anne Marie; Doumy, Gilles; Southworth, Stephen H; Marcus, Matthew A; Schoenlein, Robert W; Mukamel, Shaul; Govind, Niranjan; Khalil, Munira

2018-05-17

We present a joint experimental and computational study of the hexacyanoferrate aqueous complexes at equilibrium in the 250 meV to 7.15 keV regime. The experiments and the computations include the vibrational spectroscopy of the cyanide ligands, the valence electronic absorption spectra, and Fe 1s core hole spectra using element-specific-resonant X-ray absorption and emission techniques. Density functional theory-based quantum mechanics/molecular mechanics molecular dynamics simulations are performed to generate explicit solute-solvent configurations, which serve as inputs for the spectroscopy calculations of the experiments spanning the IR to X-ray wavelengths. The spectroscopy simulations are performed at the same level of theory across this large energy window, which allows for a systematic comparison of the effects of explicit solute-solvent interactions in the vibrational, valence electronic, and core-level spectra of hexacyanoferrate complexes in water. Although the spectroscopy of hexacyanoferrate complexes in solution has been the subject of several studies, most of the previous works have focused on a narrow energy window and have not accounted for explicit solute-solvent interactions in their spectroscopy simulations. In this work, we focus our analysis on identifying how the local solvation environment around the hexacyanoferrate complexes influences the intensity and line shape of specific spectroscopic features in the UV/vis, X-ray absorption, and valence-to-core X-ray emission spectra. The identification of these features and their relationship to solute-solvent interactions is important because hexacyanoferrate complexes serve as model systems for understanding the photochemistry and photophysics of a large class of Fe(II) and Fe(III) complexes in solution.

External-Cavity Quantum Cascade Laser Spectroscopy for Mid-IR Transmission Measurements of Proteins in Aqueous Solution.

PubMed

Alcaráz, Mirta R; Schwaighofer, Andreas; Kristament, Christian; Ramer, Georg; Brandstetter, Markus; Goicoechea, Héctor; Lendl, Bernhard

2015-07-07

In this work, we report mid-IR transmission measurements of the protein amide I band in aqueous solution at large optical paths. A tunable external-cavity quantum cascade laser (EC-QCL) operated in pulsed mode at room temperature allowed one to apply a path length of up to 38 μm, which is four times larger than that applicable with conventional FT-IR spectrometers. To minimize temperature-induced variations caused by background absorption of the ν2-vibration of water (HOH-bending) overlapping with the amide I region, a highly stable temperature control unit with relative temperature stability within 0.005 °C was developed. An advanced data processing protocol was established to overcome fluctuations in the fine structure of the emission curve that are inherent to the employed EC-QCL due to its mechanical instabilities. To allow for wavenumber accuracy, a spectral calibration method has been elaborated to reference the acquired IR spectra to the absolute positions of the water vapor absorption bands. Employing this setup, characteristic spectral features of five well-studied proteins exhibiting different secondary structures could be measured at concentrations as low as 2.5 mg mL(-1). This concentration range could previously only be accessed by IR measurements in D2O. Mathematical evaluation of the spectral overlap and comparison of second derivative spectra confirm excellent agreement of the QCL transmission measurements with protein spectra acquired by FT-IR spectroscopy. This proves the potential of the applied setup to monitor secondary structure changes of proteins in aqueous solution at extended optical path lengths, which allow experiments in flow through configuration.

Theoretical studies of UO(2)(OH)(H(2)O)(n) (+), UO(2)(OH)(2)(H(2)O)(n), NpO(2)(OH)(H(2)O)(n), and PuO(2)(OH)(H(2)O)(n) (+) (n

PubMed

Cao, Zhiji; Balasubramanian, K

2009-10-28

Extensive ab initio calculations have been carried out to study equilibrium structures, vibrational frequencies, and the nature of chemical bonds of hydrated UO(2)(OH)(+), UO(2)(OH)(2), NpO(2)(OH), and PuO(2)(OH)(+) complexes that contain up to 21 water molecules both in first and second hydration spheres in both aqueous solution and the gas phase. The structures have been further optimized by considering long-range solvent effects through a polarizable continuum dielectric model. The hydrolysis reaction Gibbs free energy of UO(2)(H(2)O)(5) (2+) is computed to be 8.11 kcal/mol at the MP2 level in good agreement with experiments. Our results reveal that it is necessary to include water molecules bound to the complex in the first hydration sphere for proper treatment of the hydrated complex and the dielectric cavity although water molecules in the second hydration sphere do not change the coordination complex. Structural reoptimization of the complex in a dielectric cavity seems inevitable to seek subtle structural variations in the solvent and to correlate with the observed spectra and thermodynamic properties in the aqueous environment. Our computations reveal dramatically different equilibrium structures in the gas phase and solution and also confirm the observed facile exchanges between the complex and bulk solvent. Complete active space multiconfiguration self-consistent field followed by multireference singles+doubles CI (MRSDCI) computations on smaller complexes confirm predominantly single-configurational nature of these species and the validity of B3LYP and MP2 techniques for these complexes in their ground states.

On the constituents of aqueous polyselenide electrolytes: A combined theoretical and Raman spectroscopic study

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

Goldbach, A.; Johnson, J.; Meisel, D.

1999-05-12

The speciation of aqueous polyselenide solutions at high pH values has been investigated by Raman and Uv/vis absorption spectroscopy. Complementary, ab initio molecular orbital calculations at the HF/6-31+G{sup *} level of theory have been carried out on the vibrational frequencies of polyselenide dianions Se{sub x}{sup 2{minus}} (x = 2--4), polyselenide radical anions Se{sub x}{sup {minus}} (x = 2, 3), and protonated polyselenides HSe{sub x}{sup {minus}} (x = 1--3) in order to substantiate the assignment of the experimental Raman spectra. Although the optical spectra suggest the successive formation of Se{sub 2}{sup 2{minus}}, Se{sub 3}{sup 2{minus}}, and Se{sub 4}{sup 2{minus}} with progressivemore » oxidation of the solutions, only two characteristic Raman bands are observed at 269 and 324 cm{sup {minus}1}. A sequence of overtones of the 269 cm{sup {minus}1} band is observed after excitation with blue light. Likewise strong overtones of the 324 cm{sup {minus}1} band appear after excitation with green light. The 269 cm{sup {minus}1} features is assigned to Se{sub 4}{sup 2{minus}} while the 324 cm{sup {minus}1} band is attributed to the radical anion Se{sub 2}{sup {minus}}. The occurrence of polyselenide radicals in aqueous solution is without precedent, and the formation of Se{sub 2}{sup {minus}} is ascribed to a photolytic process in the electrolyte. The only protonated species observed in this study is HSe{sup {minus}}, which is characterized by a Raman band at 2,303 cm{sup {minus}1}.« less

Probe conformational dynamics of proteins in aqueous solutions by terahertz spectroscopy

NASA Astrophysics Data System (ADS)

Vinh, Nguyen Q.

2016-10-01

Proteins solvated in their biologically milieu are expected to exhibit strong absorption in the terahertz frequencies, that contain information on their global and sub-global collective vibrational modes (conformational dynamics) and global dynamic correlations among solvent water and proteins. The dynamics play an important role in enzymatic activities of proteins, but obtaining an accurate and quantitative pictures of these activities, however, is challenging due to the strong absorption of water. In response, we have developed the world's highest precision, highest sensitivity terahertz-frequency domain spectrometer and a standard terahertz-time domain system to probe the collective dynamics of proteins in aqueous solutions. Operating over the frequency range from 5 GHz up to 3 THz, our spectrometers provide an unparalleled ability to probe directly such questions as the hydration level, the dynamics of water and hydrated proteins over the 100 fs to 1 ns timescale. Employing an effective medium approximation to describe the complex dielectric response of the solvated proteins in solution we find that proteins are surrounded by a loosely and tightly held layers of water molecules that behave as if they are an integral part of the protein. The number of water molecules in the protein hydration shells varies with proteins, which can tell us the average surface structure of proteins. These measurements shed light on the macromolecular motions of proteins in their biologically relevant environment.

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.

Experimentally quantifying anion polarizability at the air/water interface.

PubMed

Tong, Yujin; Zhang, Igor Ying; Campen, R Kramer

2018-04-03

The adsorption of large, polarizable anions from aqueous solution on the air/water interface controls important atmospheric chemistry and is thought to resemble anion adsorption at hydrophobic interfaces generally. While the favourability of adsorption of such ions is clear, quantifying adsorption thermodynamics has proven challenging because it requires accurate description of the structure of the anion and its solvation shell at the interface. In principle anion polarizability offers a structural window, but to the best of our knowledge there has so far been no experimental technique that allowed its characterization with interfacial specificity. Here, we meet this challenge using interface-specific vibrational spectroscopy of Cl-O vibrations of the [Formula: see text] anion at the air/water interface and report that the interface breaks the symmetry of the anion, the anisotropy of [Formula: see text]'s polarizability tensor is more than two times larger than in bulk water and concentration dependent, and concentration-dependent polarizability changes are consistent with correlated changes in surface tension.

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.

Glassy dynamics of sorbitol solutions at terahertz frequencies.

PubMed

Sibik, Juraj; Shalaev, Evgenyi Y; Zeitler, J Axel

2013-07-28

The absorption spectra of D-sorbitol and a range of its concentrated aqueous solutions were studied by terahertz spectroscopy over the temperature interval of 80 K < T < 310 K. It is shown that the slow-down of molecules at around the glass transition temperature, Tg, dramatically influences the thermal dependence of the absorption at terahertz frequencies. Furthermore, two different absorption regimes are revealed below Tg: at temperatures well below Tg, the absorption resembles the coupling of terahertz radiation to the vibrational density of states (VDOS); above these temperatures, between 160 K and Tg, in the sample of pure sorbitol and the sample of a solution of 70 wt% sorbitol in water, another type of absorption is observed at terahertz frequencies. Several possibilities of the physical origin of this absorption are discussed and based on the experimental data this process is tentatively assigned to the Johari-Goldstein β-relaxation processes shifting to lower frequencies at temperatures below Tg leaving behind a spectrum largely dominated by losses into the VDOS.

Investigation of the dynamics of aqueous proline solutions using neutron scattering and molecular dynamics simulations.

PubMed

Malo de Molina, Paula; Alvarez, Fernando; Frick, Bernhard; Wildes, Andrew; Arbe, Arantxa; Colmenero, Juan

2017-10-18

We applied quasielastic neutron scattering (QENS) techniques to samples with two different contrasts (deuterated solute/hydrogenated solvent and the opposite label) to selectively study the component dynamics of proline/water solutions. Results on diluted and concentrated solutions (31 and 6 water molecules/proline molecule, respectively) were analyzed in terms of the susceptibility and considering a recently proposed model for water dynamics [Arbe et al., Phys. Rev. Lett., 2016, 117, 185501] which includes vibrations and the convolution of localized motions and diffusion. We found that proline molecules not only reduce the average diffusion coefficient of water but also extend the time/frequency range of the crossover region ('cage') between the vibrations and purely diffusive behavior. For the high proline concentration we also found experimental evidence of water heterogeneous dynamics and a distribution of diffusion coefficients. Complementary molecular dynamics simulations show that water molecules start to perform rotational diffusion when they escape the cage regime but before the purely diffusive behavior is established. The rotational diffusion regime is also retarded by the presence of proline molecules. On the other hand, a strong coupling between proline and water diffusive dynamics which persists with decreasing temperature is directly observed using QENS. Not only are the temperature dependences of the diffusion coefficients of both components the same, but their absolute values also approach each other with increasing proline concentration. We compared our results with those reported using other techniques, in particular using dielectric spectroscopy (DS). A simple approach based on molecular hydrodynamics and a molecular treatment of DS allows rationalizing the a priori puzzling inconsistency between QENS and dielectric results regarding the dynamic coupling of the two components. The interpretation proposed is based on general grounds and therefore should be applicable to other biomolecular solutions.

Novel SiO2-deposited CaF2 substrate for vibrational sum-frequency generation (SFG) measurements of chemisorbed monolayers in an aqueous environment.

PubMed

Padermshoke, Adchara; Konishi, Shouta; Ara, Masato; Tada, Hirokazu; Ishibashi, Taka-Aki

2012-06-01

A novel SiO(2)-deposited CaF(2) (SiO(2)/CaF(2)) substrate for measuring vibrational sum-frequency generation (SFG) spectra of silane-based chemisorbed monolayers in aqueous media has been developed. The substrate is suitable for silanization and transparent over a broad range of the infrared (IR) probe. The present work demonstrates the practical application of the SiO(2)/CaF(2) substrate and, to our knowledge, the first SFG spectrum at the solid/water interface of a silanized monolayer observed over the IR fingerprint region (1780-1400 cm(-1)) using a back-side probing geometry. This new substrate can be very useful for SFG studies of various chemisorbed organic molecules, particularly biological compounds, in aqueous environments.

Subterahertz Longitudinal Phonon Modes Propagating in a Lipid Bilayer Immersed in an Aqueous Medium

NASA Astrophysics Data System (ADS)

Zakhvataev, V. E.

2018-04-01

The properties of subterahertz longitudinal acoustic phonon modes in the hydrophobic region of a lipid bilayer immersed in a compressible viscous aqueous medium are investigated theoretically. An approximate expression is obtained for the Mandelstam-Brillouin components of the dynamic structure factor of a bilayer. The analysis is based on a generalized hydrodynamic model of the "two-dimensional lipid bilayer + three-dimensional fluid medium" system, as well as on known sharp estimates for the frequencies and lifetimes of long-wavelength longitudinal acoustic phonons in a free hydrated lipid bilayer and in water, obtained from inelastic X-ray scattering experiments and molecular dynamics simulations. It is shown that, for characteristic values of the parameters of the membrane system, subterahertz longitudinal phonon-like excitations in the hydrophobic part of the bilayer are underdamped. In this case, the contribution of the viscous flow of the aqueous medium to the damping of a longitudinal membrane mode is small compared with the contribution of the lipid bilayer. Quantitative estimates of the damping ratio agree well with the experimental results for the vibration mode of the enzyme lysozyme in aqueous solution [1]. It is also shown that a coupling between longitudinal phonon modes of the bilayer and relaxation processes in its fluid environment gives rise to an additional peak in the scattering spectrum, which corresponds to a non-propagating mode.

Cysteine-Functionalized Chitosan Magnetic Nano-Based Particles for the Recovery of Light and Heavy Rare Earth Metals: Uptake Kinetics and Sorption Isotherms

PubMed Central

Galhoum, Ahmed A.; Mafhouz, Mohammad G.; Abdel-Rehem, Sayed T.; Gomaa, Nabawia A.; Atia, Asem A.; Vincent, Thierry; Guibal, Eric

2015-01-01

Cysteine-functionalized chitosan magnetic nano-based particles were synthesized for the sorption of light and heavy rare earth (RE) metal ions (La(III), Nd(III) and Yb(III)). The structural, surface, and magnetic properties of nano-sized sorbent were investigated by elemental analysis, FTIR, XRD, TEM and VSM (vibrating sample magnetometry). Experimental data show that the pseudo second-order rate equation fits the kinetic profiles well, while sorption isotherms are described by the Langmuir model. Thermodynamic constants (ΔG°, ΔH°) demonstrate the spontaneous and endothermic nature of sorption. Yb(III) (heavy RE) was selectively sorbed while light RE metal ions La(III) and Nd(III) were concentrated/enriched in the solution. Cationic species RE(III) in aqueous solution can be adsorbed by the combination of chelating and anion-exchange mechanisms. The sorbent can be efficiently regenerated using acidified thiourea. PMID:28347004

A delicate case of unidirectional proton transfer from water to an aromatic heterocyclic anion.

PubMed

Biswas, Sohag; Mallik, Bhabani S

2016-11-21

We present the characteristic proton transfer process from water to the pyrazole anion, infrared signatures of hydroxyl groups and the free energy profile of the process in aqueous solution combining first principles simulations, wavelet analysis and metadynamics. Our results show that the presence of minimum three water molecules in the gas phase cluster with a particular arrangement is sufficient to facilitate the proton transfer process from water to the anion. The overall reaction is very rapid in aqueous solution, and the free energy barrier for this process is found to be 4.2 kcal mol -1 . One of the earlier reported fundamental reasons for the transfer of proton from water to the anion is the change in the acidity of OH groups surrounding the anion. We have correlated the stretching frequencies of the surrounding OH groups with this acidity. We find that the development of less energetic vibrational states, and the OH mode having lowest average stretching frequency contains the most acidic proton. A large frequency shift of the OH mode belonging to one of the surrounding water molecules is observed during the transfer of proton from water to the anion; this shift is due to the change in acidity of the adjacent hydroxyl groups in the vicinity of the anion.

Excited States and Luminescent Properties of UO 2F 2 and Its Solvated Complexes in Aqueous Solution

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

Su, Jing; Wang, Zheming; Pan, Duoqiang

2014-07-21

The electronic absorption and emission spectra of free UO 2F 2 and its water solvated complexes below 32 000 cm –1 are investigated at the levels of ab initio CASPT2 and CCSD(T) with inclusion of scalar relativistic and spin–orbit coupling effects. The influence of the water coordination on the electronic spectra of UO 2F 2 is explored by investigating the excited states of solvated complexes (H 2O) nUO 2F 2 (n = 1–3). In these uranyl complexes, water coordination is found to have appreciable influence on the 3Δ (Ω = 1 g) character of the luminescent state and on themore » electronic spectral shape. The simulated luminescence spectral curves based on the calculated spectral parameters of (H 2O) nUO 2F 2 from CCSD(T) approach agree well with experimental spectra in aqueous solution at both near-liquid-helium temperature and room temperature. The possible luminescence spectra of free UO 2F 2 in gas phase are predicted on the basis of CASPT2 and CCSD(T) results, respectively, by considering three symmetric vibration modes. Finally, the effect of competition between spin–orbit coupling and ligand field repulsion on the luminescent state properties is discussed.« less

Compact Solid-State 213 nm Laser Enables Standoff Deep Ultraviolet Raman Spectrometer: Measurements of Nitrate Photochemistry.

PubMed

Bykov, Sergei V; Mao, Michael; Gares, Katie L; Asher, Sanford A

2015-08-01

We describe a new compact acousto-optically Q-switched diode-pumped solid-state (DPSS) intracavity frequency-tripled neodymium-doped yttrium vanadate laser capable of producing ~100 mW of 213 nm power quasi-continuous wave as 15 ns pulses at a 30 kHz repetition rate. We use this new laser in a prototype of a deep ultraviolet (UV) Raman standoff spectrometer. We use a novel high-throughput, high-resolution Echelle Raman spectrograph. We measure the deep UV resonance Raman (UVRR) spectra of solid and solution sodium nitrate (NaNO3) and ammonium nitrate (NH4NO3) at a standoff distance of ~2.2 m. For this 2.2 m standoff distance and a 1 min spectral accumulation time, where we only monitor the symmetric stretching band, we find a solid state NaNO3 detection limit of ~100 μg/cm(2). We easily detect ~20 μM nitrate water solutions in 1 cm path length cells. As expected, the aqueous solutions UVRR spectra of NaNO3 and NH4NO3 are similar, showing selective resonance enhancement of the nitrate (NO3(-)) vibrations. The aqueous solution photochemistry is also similar, showing facile conversion of NO3(-) to nitrite (NO2(-)). In contrast, the observed UVRR spectra of NaNO3 and NH4NO3 powders significantly differ, because their solid-state photochemistries differ. Whereas solid NaNO3 photoconverts with a very low quantum yield to NaNO2, the NH4NO3 degrades with an apparent quantum yield of ~0.2 to gaseous species.

Vibrational dynamics of hydrogen-bonded complexes in solutions studied with ultrafast infrared pump-probe spectroscopy.

PubMed

Banno, Motohiro; Ohta, Kaoru; Yamaguchi, Sayuri; Hirai, Satori; Tominaga, Keisuke

2009-09-15

In aqueous solution, the basis of all living processes, hydrogen bonding exerts a powerful effect on chemical reactivity. The vibrational energy relaxation (VER) process in hydrogen-bonded complexes in solution is sensitive to the microscopic environment around the oscillator and to the geometrical configuration of the hydrogen-bonded complexes. In this Account, we describe the use of time-resolved infrared (IR) pump-probe spectroscopy to study the vibrational dynamics of (i) the carbonyl CO stretching modes in protic solvents and (ii) the OH stretching modes of phenol and carboxylic acid. In these cases, the carbonyl group acts as a hydrogen-bond acceptor, whereas the hydroxyl group acts as a hydrogen-bond donor. These vibrational modes have different properties depending on their respective chemical bonds, suggesting that hydrogen bonding may have different mechanisms and effects on the VER of the CO and OH modes than previously understood. The IR pump-probe signals of the CO stretching mode of 9-fluorenone and methyl acetate in alcohol, as well as that of acetic acid in water, include several components with different time constants. Quantum chemical calculations indicate that the dynamical components are the result of various hydrogen-bonded complexes that form between solute and solvent molecules. The acceleration of the VER is due to the increasing vibrational density of states caused by the formation of hydrogen bonds. The vibrational dynamics of the OH stretching mode in hydrogen-bonded complexes were studied in several systems. For phenol-base complexes, the decay time constant of the pump-probe signal decreases as the band peak of the IR absorption spectrum shifts to lower wavenumbers (the result of changing the proton acceptor). For phenol oligomers, the decay time constant of the pump-probe signal decreases as the probe wavenumber decreases. These observations show that the VER time strongly correlates with the strength of hydrogen bonding. This acceleration may be due to increased coupling between the OH stretching mode and the accepting mode of the VER, because the low-frequency shift caused by hydrogen bond formation is very large. Unlike phenol oligomers, however, the pump-probe signals of phenol-base complexes did not exhibit probe frequency dependence. For these complexes, rapid interconversion between different conformations causes rapid fluctuations in the vibrational frequency of the OH stretching modes, and these fluctuations level the VER times of different conformations. For the benzoic acid dimer, a quantum beat at a frequency of around 100 cm(-1) is superimposed on the pump-probe signal. This result indicates the presence of strong anharmonic coupling between the intramolecular OH stretching and the intermolecular stretching modes. From a two-dimensional plot of the OH stretching wavenumber and the low-frequency wavenumber, the wavenumber of the low-frequency mode is found to increase monotonically as the probe wavenumber is shifted toward lower wavenumbers. Our results represent a quantitative determination of the acceleration of VER by the formation of hydrogen bonds. Our studies merit further evaluation and raise fundamental questions about the current theory of vibrational dynamics in the condensed phase.

Studies of anions sorption on natural zeolites.

PubMed

Barczyk, K; Mozgawa, W; Król, M

2014-12-10

This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. Copyright © 2014 Elsevier B.V. All rights reserved.

Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP).

PubMed

Cipolloni, Marco; Kaleta, Jiří; Mašát, Milan; Dron, Paul I; Shen, Yongqiang; Zhao, Ke; Rogers, Charles T; Shoemaker, Richard K; Michl, Josef

2015-04-23

We examine the fluorescence anisotropy of rod-shaped guests held inside the channels of tris( o -phenylenedioxy)cyclotriphosphazene (TPP) host nanocrystals, characterized by powder X-ray diffraction and solid state NMR spectroscopy. We address two issues: (i) are light polarization measurements on an aqueous colloidal solution of TPP nanocrystals meaningful, or is depolarization by scattering excessive? (ii) Can measurements of the rotational mobility of the included guests be performed at low enough loading levels to suppress depolarization by intercrystallite energy transfer? We find that meaningful measurements are possible and demonstrate that the long axis of molecular rods included in TPP channels performs negligible vibrational motion.

The computational analysis and modelling of substitution effects on hydrolysis of formanilides in acidic aqueous solutions

NASA Astrophysics Data System (ADS)

Lukeš, Vladimír; Škorňa, Peter; Michalík, Martin; Klein, Erik

2017-11-01

Various para, meta and ortho substituted formanilides have been theoretically studied. For trans and cis-isomers of non-substituted formanilide, the calculated B3LYP vibration normal modes were analyzed. Substituent effect on the selected normal modes was described and the comparison with the available experimental data is presented. The calculated B3LYP proton affinities were correlated with Hammett constants, Fujita-Nishioka equation and the rate constants of the hydrolysis in 1 M HCl. Found linear dependences allow predictions of dissociation constants (pKBH+) and hydrolysis rate constants. Obtained results indicate that protonation of amide group may represent the rate determining step of acid catalyzed hydrolysis.

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.

Conformational, vibrational and DFT studies of a newly synthesized arylpiperazine-based drug and evaluation of its reactivity towards the human GABA receptor

NASA Astrophysics Data System (ADS)

Onawole, A. T.; Al-Ahmadi, A. F.; Mary, Y. S.; Panicker, C. Y.; Ullah, N.; Armaković, S.; Armaković, S. J.; Van Alsenoy, C.; Al-Saadi, A. A.

2017-11-01

This study reports a computational assessment of important biochemical properties and vibrational assignments for the synthesized 1-(4-(3-methoxy-4-nitrophenyl)piperazin-1-yl)ethanone (MNPE). MNPE is related to the commonly used arylpiperazine-based drugs that exhibit a wide range of pharmacological activities. The characterization of MNPE is based on the readily sighted 1363 cm-1 infrared band (associated with piperazine ring stretching), 1308 cm-1 Raman line (associated with the phenyl ring breathing), 1242 cm-1 Raman line and 1092 cm-1 infrared band (both associated with Csbnd N stretching) as key modes in its vibrational spectra. First principle calculations revealed that MNPE could exist in sixteen different plausible conformations, which were used as basis to understand the possible molecular docking mechanism of the molecule as an agonist in the human GABAA receptor. The best binding scenarios showed the presence of intramolecular hydrogen bonding in MNPE and was comparable with the most stable configuration. It was further evaluated for its reactivity properties by utilizing the concepts of Average Local Ionization Energies (ALIE) and Fukui functions. The autoxidation and hydrolysis degradation likelihood of MNPE estimated from the computed bond dissociation energies and radial distribution functions predicted that MNPE is to be readily biodegradable in aqueous solutions.

Vibrational spectra, optical properties, NBO and HOMO-LUMO analysis of L-Phenylalanine L-Phenylalaninium Perchlorate: DFT calculations

NASA Astrophysics Data System (ADS)

Elleuch, Nabil; Ben Ahmed, Ali; Feki, Habib; Abid, Younes; Minot, Christian

2014-03-01

In this work, we report a combined experimental and theoretical study of a nonlinear optical material, L-Phenylalanine L-Phenylalaninium Perchlorate. Single crystals of the title compound have been grown by slow evaporation of an aqueous solution at room temperature. Theoretical calculations were preceded by redetermination of the crystal X-ray structure. The compound crystallizes in the non-centro symmetric space group P212121 of the orthorhombic system. The FT-IR and Raman spectra of the crystal were recorded and analyzed. The density functional theory (DFT) computations have been performed at B3LYP/6-31G(d) level to derive equilibrium geometry, vibrational wavenumbers, intensity and NLO properties. All observed vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our DFT calculations as a primary source of attribution and also by comparison with the previous results for similar compounds. Natural bond orbital analysis was carried out to demonstrate the various inter-and intramolecular interaction that are responsible of the stabilization of the compound. The lowering of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap appears to be the cause of its enhanced charge transfer interaction leading to high NLO activity.

Study of the adsorption of sodium dodecyl sulfate (SDS) at the air/water interface: targeting the sulfate headgroup using vibrational sum frequency spectroscopy.

PubMed

Johnson, C Magnus; Tyrode, Eric

2005-07-07

The surface sensitive technique vibrational sum frequency spectroscopy (VSFS), has been used to study the adsorption behaviour of SDS to the liquid/vapour interface of aqueous solutions, specifically targeting the sulfate headgroup stretches. In the spectral region extending from 980 to 1850 cm(-1), only the vibrations due to the SO(3) group were detectable. The fitted amplitudes for the symmetric SO(3) stretch observed at 1070 cm(-1) for the polarization combinations ssp and ppp, were seen to follow the adsorption isotherm calculated from surface tension measurements. The orientation of the sulfate headgroup in the concentration range spanning from 1.0 mM to above the critical micellar concentration (c.m.c.) was observed to remain constant within experimental error, with the pseudo-C(3) axis close to the surface normal. Furthermore, the effect of increasing amounts of sodium chloride at SDS concentrations above c.m.c. was also studied, showing an increase of approximately 12% in the fitted amplitude for the symmetric SO(3) stretch when increasing the ionic strength from 0 to 300 mM NaCl. Interestingly, the orientation of the SDS headgroup was also observed to remain constant within this concentration range and identical to the case without NaCl.

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.

Method for non-contact particle manipulation and control of particle spacing along an axis

DOEpatents

Goddard, Gregory Russ; Kaduchak, Gregory; Jett, James Hubert; Graves, Steven Wayde

2013-09-10

One or more of the embodiments of the present invention provide for a method of non-contact particle manipulation and control of particle spacing along an axis which includes axial and radial acoustic standing wave fields. Particles are suspended in an aqueous solution, and this solution then flows into the cylindrical flow channel. While the solution flows through the flow channel, the outer structure of the flow channel is vibrated at a resonant frequency, causing a radial acoustic standing wave field to form inside the flow channel in the solution. These radial acoustic standing waves focus the particles suspended in the solution to the center axis of the cylindrical flow channel. At the same time, a transducer is used to create an axial acoustic standing wave field in the flow channel parallel to the axis of the flow channel. This drives the particles, which are already being focused to the center axis of the flow channel, to nodes or anti-nodes of the axial standing wave at half-wavelength intervals, depending on whether the particles are more or less dense and more or less compressible than the surrounding fluid.

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.

Evaluating structures, properties and vibrational and electronic spectra of the potassium 2-isonicotinoyltrifluoroborate salt

NASA Astrophysics Data System (ADS)

Iramain, Maximiliano A.; Davies, Lilian; Brandán, Silvia Antonia

2018-07-01

The potassium 2-isonicotinoyltrifluorborate salt has been characterized by using FT-IR, FT-Raman and UV-Visible spectroscopies while its structural properties were studied by using B3LYP/6-31G* and B3LYP/6-311++G** calculations in gas and aqueous solution phases. Four conformers with CS and C1 symmetries were found in the potential energy surfaces but only one of them presents the minimum energy. Two dimeric species of this salt were also optimized in accordance to the layered architectures suggested for trifluoroborate potassium salts in the solid phase. Here, the experimental Raman bands at 796, 748 and 676 cm-1 clearly support the presence of both dimers. On the other hand, the 2-isonicotinoyltrifluorborate anion was optimized because its presence is expected in solution. Reasonable correlations were observed between the predicted FTIR, Raman and UV-visible spectra with the corresponding experimental ones. The solvation energies for the salt in aqueous solution were predicted by using both methods. Here, it is observed that the change of furane by pyridine ring generates an increase in the solvation energies of the potassium 2-isonicotinoyltrifluorborate salt in relation to potassium 3-furoyltrifluoroborate salt. The study of the charges has revealed that there is an effect of the size of the basis set on the Mulliken charges while the AIM analyses suggest that the F⋯H and O⋯K interactions are also strongly dependent of the medium and the size of the basis sets. The bond orders for the F and K atoms evidence their higher ionic characteristics in solution with both basis sets. The NBO and AIM results clearly support the higher stability of this salt in both media. The studies by using the frontier orbitals indicate that the change of furane by pyridine ring decreases the reactivity of this salt by using 6-31G* basis set but increases when the other one is employed. Another effect of change of furane by pyridine ring is observed in the increase of the f(νCdbnd O) and f(νBF3) force constants. In addition, the force fields for the salt in both media were reported together to their complete vibrational assignments and force constants by using both levels of theory.

Amine Chemistry at Aqueous Interfaces: The Study of Organic Amines in Neutralizing Acidic Gases at an Air/Water Surface Using Vibrational Sum Frequency Spectroscopy

NASA Astrophysics Data System (ADS)

McWilliams, L.; Wren, S. N.; Valley, N. A.; Richmond, G.

2014-12-01

Small organic bases have been measured in atmospheric samples, with their sources ranging from industrial processing to animal husbandry. These small organic amines are often highly soluble, being found in atmospheric condensed phases such as fogwater and rainwater. Additionally, they display acid-neutralization ability often greater than ammonia, yet little is known regarding their kinetic and thermodynamic properties. This presentation will describe the molecular level details of a model amine system at the vapor/liquid interface in the presence of acidic gas. We find that this amine system shows very unique properties in terms of its bonding, structure, and orientation at aqueous surfaces. The results of our studies using a combination of computation, vibrational sum frequency spectroscopy, and surface tension will report the properties inherent to these atmospherically relevant species at aqueous surfaces.

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.

On the intermolecular vibrational coupling, hydrogen bonding, and librational freedom of water in the hydration shell of mono- and bivalent anions.

PubMed

Ahmed, Mohammed; Namboodiri, V; Singh, Ajay K; Mondal, Jahur A

2014-10-28

The hydration energy of an ion largely resides within the first few layers of water molecules in its hydration shell. Hence, it is important to understand the transformation of water properties, such as hydrogen-bonding, intermolecular vibrational coupling, and librational freedom in the hydration shell of ions. We investigated these properties in the hydration shell of mono- (Cl(-) and I(-)) and bivalent (SO4(2-) and CO3(2-)) anions by using Raman multivariate curve resolution (Raman-MCR) spectroscopy in the OH stretch, HOH bend, and [bend+librational] combination bands of water. Raman-MCR of aqueous Na-salt (NaCl, NaI, Na2SO4, and Na2CO3) solutions provides ion-correlated spectra (IC-spectrum) which predominantly bear the vibrational characteristics of water in the hydration shell of respective anions. Comparison of these IC-spectra with the Raman spectrum of bulk water in different spectral regions reveals that the water is vibrationally decoupled with its neighbors in the hydration shell. Hydrogen-bond strength and librational freedom also vary with the nature of anion: hydrogen-bond strength, for example, decreases as CO3(2-) > SO4(2-) > bulk water ≈ Cl(-) > I(-); and the librational freedom increases as CO3(2-) ≈ SO4(2-) < bulk water < Cl(-) < I(-). It is believed that these structural perturbations influence the dynamics of coherent energy transfer and librational reorientation of water in the hydration shell of anions.

Vibrational, DFT, and thermal analysis of 2,4,6-triamino-1,3,5-triazin-1-ium 3-(prop-2-enoyloxy) propanoate acrylic acid monosolvate monohydrate

NASA Astrophysics Data System (ADS)

Sangeetha, V.; Govindarajan, M.; Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Anbalagan, G.

2013-12-01

New organic crystals of 2,4,6-triamino-1,3,5-triazin-1-ium 3-(prop-2-enoyloxy) propanoate acrylic acid monosolvate monohydrate (MAC) have been obtained from aqueous solution by the slow solvent evaporation method at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallises in the triclinic system with centrosymmetric space group P-1. FT-IR and FT-Raman spectra of MAC have been recorded and analyzed. The molecular geometry and vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimization based on density functional theory (DFT) B3LYP method with 6-31G(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction data. The theoretical results show that the optimized geometry can well reproduce the crystal structure, and the calculated vibrational frequency values show good agreement with experimental values. A study of the electronic properties, such as HOMO and LUMO energies and Molecular electrostatic potential (MEP) were performed. Mulliken charges and NBO charges of the title molecule were also calculated and interpreted. Thermogravimetric analysis has been done to study the thermal behaviour of MAC. The 13C and 1H nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

Structural and vibrational spectroscopic studies on charge transfer and ionic hydrogen bonding interactions of melaminium benzoate dihydrate

NASA Astrophysics Data System (ADS)

Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Gunasekaran, S.; Rajakumar, P. R.; Anbalagan, G.

2015-06-01

Single crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by the slow solvent evaporation method at room temperature. Crystalline nature of the grown crystal has been confirmed by X-ray powder diffraction studies. The optimized geometry, frequency and intensity of the vibrational bands of MBDH were obtained by the Hartree-Fock and density functional theory using B3LYP/cam-B3LYP with 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with the experimental FT-IR and FT-Raman spectral values. The obtained vibrational wavenumbers and optimized geometric parameters are found to be in good agreement with the experimental data. UV-Visible spectrum was recorded in the region 200-400 nm and the electronic properties, HOMO-LUMO energies and other related electronic parameters are calculated. The isotropic chemical shifts computed by 1H and 13C NMR analysis also show good agreement with experimental observation. Natural bond orbital (NBO) analysis has been performed on MBDH compound to analyze the stability of the molecule arising from hyperconjugative interactions and charge delocalization. Molecular electrostatic potential surface (MEP) has also been performed by DFT/cam-B3LYP method with 6-311++G(d,p) basis set. Differential scanning calorimetric measurements performed on the powder sample indicate the phase transition point approximately at 368 and 358 K for heating and cooling, respectively.

Structural and vibrational spectroscopic studies on charge transfer and ionic hydrogen bonding interactions of melaminium benzoate dihydrate.

PubMed

Kanagathara, N; Marchewka, M K; Drozd, M; Gunasekaran, S; Rajakumar, P R; Anbalagan, G

2015-06-15

Single crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by the slow solvent evaporation method at room temperature. Crystalline nature of the grown crystal has been confirmed by X-ray powder diffraction studies. The optimized geometry, frequency and intensity of the vibrational bands of MBDH were obtained by the Hartree-Fock and density functional theory using B3LYP/cam-B3LYP with 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with the experimental FT-IR and FT-Raman spectral values. The obtained vibrational wavenumbers and optimized geometric parameters are found to be in good agreement with the experimental data. UV-Visible spectrum was recorded in the region 200-400 nm and the electronic properties, HOMO-LUMO energies and other related electronic parameters are calculated. The isotropic chemical shifts computed by (1)H and (13)C NMR analysis also show good agreement with experimental observation. Natural bond orbital (NBO) analysis has been performed on MBDH compound to analyze the stability of the molecule arising from hyperconjugative interactions and charge delocalization. Molecular electrostatic potential surface (MEP) has also been performed by DFT/cam-B3LYP method with 6-311++G(d,p) basis set. Differential scanning calorimetric measurements performed on the powder sample indicate the phase transition point approximately at 368 and 358K for heating and cooling, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Two-dimensional infrared spectral signature and hydration of the oxalate dianion

PubMed Central

Kuroda, Daniel G.; Hochstrasser, Robin M.

2011-01-01

Ultrafast vibrational spectra of the aqueous oxalate ion in the region of its carboxylate asymmetric stretch modes show novel relaxation processes. Two-dimensional infrared vibrational echo spectra and the vibrational dynamics obtained from them along with measurements of the anisotropy decay provide a picture in which the localization of the oxalate vibrational excitation onto the carboxylate groups occurs in ∼450 fs. Molecular dynamics simulations are used to characterize the vibrational dynamics in terms of dihedral angle motion between the two carboxylate planes and solvation dynamics. The localization of the oxalate vibrational excitation onto the carboxylates is induced by the fluctuations in the carboxylate vibrational frequencies which are shown by theory and experiment to have a similar correlation time as the anisotropy decay. PMID:22128938

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.

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.

Effects of protein conformational flexibilities and electrostatic interactions on the low-frequency vibrational spectrum of hydration water.

PubMed

Pal, Somedatta; Bandyopadhyay, Sanjoy

2013-05-16

The conformational flexibility of a protein and its ability to form hydrogen bonds with water are expected to influence the microscopic properties of water layer hydrating the protein. Detailed molecular dynamics simulations with an aqueous solution of the globular protein barstar have been carried out to explore such influence on the low-frequency vibrational spectrum of the hydration water molecules. The calculations reveal that enhanced degree of confinement at the protein surface on freezing its local motions leads to increasingly restricted oscillatory motions of the hydration water molecules as evident from larger blue shifts of the corresponding band. Interestingly, conformational fluctuations of the protein and electrostatic component of its interaction with the solvent have been found to affect the transverse and longitudinal oscillations of hydration water molecules in a nonuniform manner. It is further noticed that the distributions of the low-frequency modes for the water molecules hydrogen bonded to the residues of different segments of the protein are heterogeneously altered. The effect is more around the frozen protein matrix and agrees well with slower protein-water hydrogen bond relaxations.

How to identify water from thickener aqueous solutions by touch.

PubMed

Nonomura, Yoshimune; Miura, Taku; Miyashita, Takaaki; Asao, Yuka; Shirado, Hirokazu; Makino, Yasutoshi; Maeno, Takashi

2012-06-07

Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner's corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment.

How to identify water from thickener aqueous solutions by touch

PubMed Central

Nonomura, Yoshimune; Miura, Taku; Miyashita, Takaaki; Asao, Yuka; Shirado, Hirokazu; Makino, Yasutoshi; Maeno, Takashi

2012-01-01

Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner's corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment. PMID:22072449

Water: a responsive small molecule.

PubMed

Shultz, Mary Jane; Vu, Tuan Hoang; Meyer, Bryce; Bisson, Patrick

2012-01-17

Unique among small molecules, water forms a nearly tetrahedral yet flexible hydrogen-bond network. In addition to its flexibility, this network is dynamic: bonds are formed or broken on a picosecond time scale. These unique features make probing the local structure of water challenging. Despite the challenges, there is intense interest in developing a picture of the local water structure due to water's fundamental importance in many fields of chemistry. Understanding changes in the local network structure of water near solutes likely holds the key to unlock problems from analyzing parameters that determine the three dimensional structure of proteins to modeling the fate of volatile materials released into the atmosphere. Pictures of the local structure of water are heavily influenced by what is known about the structure of ice. In hexagonal I(h) ice, the most stable form of solid water under ordinary conditions, water has an equal number of donor and acceptor bonds; a kind of symmetry. This symmetric tetrahedral coordination is only approximately preserved in the liquid. The most obvious manifestation of this altered tetrahedral bonding is the greater density in the liquid compared with the solid. Formation of an interface or addition of solutes further modifies the local bonding in water. Because the O-H stretching frequency is sensitive to the environment, vibrational spectroscopy provides an excellent probe for the hydrogen-bond structure in water. In this Account, we examine both local interactions between water and small solutes and longer range interactions at the aqueous surface. Locally, the results suggest that water is not a symmetric donor or acceptor, but rather has a propensity to act as an acceptor. In interactions with hydrocarbons, action is centered at the water oxygen. For soluble inorganic salts, interaction is greater with the cation than the anion. The vibrational spectrum of the surface of salt solutions is altered compared with that of neat water. Studies of local salt-water interactions suggest that the picture of the local water structure and the ion distribution at the surface deduced from the surface vibrational spectrum should encompass both ions of the salt.

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)

FT-IR, FT-Raman and UV-visible spectra of potassium 3-furoyltrifluoroborate salt

NASA Astrophysics Data System (ADS)

Iramain, Maximiliano A.; Davies, Lilian; Brandán, Silvia Antonia

2018-04-01

The potassium 3-furoyltrifluoroborate salt has been experimentally characterized by means of FT-IR, FT-Raman and UV-Visible spectroscopies. Here, the predicted FT-IR, FT-Raman and UV-visible spectra by using theoretical B3LYP/6-31G* and 6-311++G** calculations show very good correlations with the corresponding experimental ones. The solvation energies were predicted by using both levels of calculations. The NBO analyses reveal the high stability of the salt by using the B3LYP/6-31G* level of theory while the AIM studies evidence the ionic characteristics of the salt in both media. The strong blue colour observed on the K atom by using the molecular electrostatic potential mapped suggests that this region act as typical electrophilic site. The gap values have revealed that the salt in gas phase is more reactive than in solution, as was reported in the literature while, the F13⋯H6 interaction together with the Ksbnd O bond observed by the studies of their charges could probably modulate the reactivities of this salt in aqueous solution. The force fields were computed with the SQMFF methodology and the Molvib program to perform the complete vibrational analysis. Then, the 39 vibration normal modes classified as 26 A'+ 13 A″ were completely assigned and their force constants are also reported.

Surface-enhanced Raman spectroscopy of the anti-cancer drug irinotecan in presence of human serum albumin.

PubMed

Vicario, A; Sergo, V; Toffoli, G; Bonifacio, A

2015-03-01

The development of nanotechnological devices and their clinical application in medicine has become increasingly important, especially in the context of targeted and personalized therapy. This is particularly important in cancer therapy, where antitumor drugs are highly cytotoxic and often exert their therapeutic effect at concentrations close to systemic toxicity. In the last years a growing number of studies has started to report the use of plasmonic nanoprobes in the field of theranostics, broadening the application of vibrational spectroscopies like Raman scattering and surface enhanced Raman scattering (SERS) in biomedicine. The present work aims to identify and characterize the vibrational profiles of a widely used anticancer drug, irinotecan (CPT-11). With a rational approach, SERS experiments have been performed on this analyte employing both Au and Ag colloids, starting from simple aqueous solutions up to albumin mixtures. A major step forward for drug detection in albumin solutions has been taken with the adoption of a simple deproteinization strategy, and a two-in-one-step separation and identification by coupling thin layer chromatography, TLC, with SERS (TLC-SERS). The latter has revealed to be a valid system for protein separation and simultaneous analyte detection, showing a potential to become an innovative, sensitive and low cost method for antineoplastic drug profiling in patients' body fluids. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

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.

Vibrational spectra of water solutions of azoles from QM/MM calculations: effects of solvation.

PubMed

Tanzi, Luana; Ramondo, Fabio; Guidoni, Leonardo

2012-10-18

Using microsolvation models and mixed quantum/classical ab initio molecular dynamics simulations, we investigate the vibrational properties of two azoles in water solution: pyrazole and oxazole. The effects of the water-azole hydrogen bonding are rationalized by an extensive comparison between structural parameters and harmonic frequencies obtained by microsolvation models. Following the effective normal-mode analysis introduced by Martinez et al. [Martinez et al., J. Chem. Phys. 2006, 125, 144106], we identify the vibrational frequencies of the solutes using the decomposition of the vibrational density of states of the gas phase and solution dynamics. The calculated shifts from gas phase to solution are fairly in agreement with the available experimental data.

Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP)

PubMed Central

2015-01-01

We examine the fluorescence anisotropy of rod-shaped guests held inside the channels of tris(o-phenylenedioxy)cyclotriphosphazene (TPP) host nanocrystals, characterized by powder X-ray diffraction and solid state NMR spectroscopy. We address two issues: (i) are light polarization measurements on an aqueous colloidal solution of TPP nanocrystals meaningful, or is depolarization by scattering excessive? (ii) Can measurements of the rotational mobility of the included guests be performed at low enough loading levels to suppress depolarization by intercrystallite energy transfer? We find that meaningful measurements are possible and demonstrate that the long axis of molecular rods included in TPP channels performs negligible vibrational motion. PMID:25937858

Removal of р-nitrophenol from aqueous solution by magnetically modified activated carbon

NASA Astrophysics Data System (ADS)

Han, Shuai; Zhao, Feng; Sun, Jian; Wang, Bin; Wei, Rongyan; Yan, Shiqiang

2013-09-01

Activated carbon was modified with γ-Fe2O3 nanoparticles, using the chemical co-precipitation technique and the carboxylic acid vapor treatment technique. Two magnetic composites were characterized and compared by Fourier Transform Infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry and nitrogen adsorption-desorption. Then the two materials were used to remove p-nitrophenol in water. The equilibrium data revealed that the Langmuir isotherm was better in fitting the experiment result than the Freundlich isotherm, and the sorption capacity of the nanocomposite made by the chemical co-precipitation technique was higher than that of the other one. We suggest that the chemical co-precipitation technique is a more efficient and practical method to produce magnetically modified activated carbon.

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.

Near-Infrared-Induced Heating of Confined Water in Polymeric Particles for Efficient Payload Release

PubMed Central

2015-01-01

Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on biological research by enabling remote and spatiotemporal control over the release of encapsulated cargo. The few existing mechanisms for NIR-triggered release have not been widely applied because they require custom synthesis of designer polymers, high-powered lasers to drive inefficient two-photon processes, and/or coencapsulation of bulky inorganic particles. In search of a simpler mechanism, we found that exposure to laser light resonant with the vibrational absorption of water (980 nm) in the NIR region can induce release of payloads encapsulated in particles made from inherently non-photo-responsive polymers. We hypothesize that confined water pockets present in hydrated polymer particles absorb electromagnetic energy and transfer it to the polymer matrix, inducing a thermal phase change. In this study, we show that this simple and highly universal strategy enables instantaneous and controlled release of payloads in aqueous environments as well as in living cells using both pulsed and continuous wavelength lasers without significant heating of the surrounding aqueous solution. PMID:24717072

Near-infrared-induced heating of confined water in polymeric particles for efficient payload release.

PubMed

Viger, Mathieu L; Sheng, Wangzhong; Doré, Kim; Alhasan, Ali H; Carling, Carl-Johan; Lux, Jacques; de Gracia Lux, Caroline; Grossman, Madeleine; Malinow, Roberto; Almutairi, Adah

2014-05-27

Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on biological research by enabling remote and spatiotemporal control over the release of encapsulated cargo. The few existing mechanisms for NIR-triggered release have not been widely applied because they require custom synthesis of designer polymers, high-powered lasers to drive inefficient two-photon processes, and/or coencapsulation of bulky inorganic particles. In search of a simpler mechanism, we found that exposure to laser light resonant with the vibrational absorption of water (980 nm) in the NIR region can induce release of payloads encapsulated in particles made from inherently non-photo-responsive polymers. We hypothesize that confined water pockets present in hydrated polymer particles absorb electromagnetic energy and transfer it to the polymer matrix, inducing a thermal phase change. In this study, we show that this simple and highly universal strategy enables instantaneous and controlled release of payloads in aqueous environments as well as in living cells using both pulsed and continuous wavelength lasers without significant heating of the surrounding aqueous solution.

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.

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.

Adsorption of C.I. Reactive Red 228 and Congo Red dye from aqueous solution by amino-functionalized Fe3O4 particles: kinetics, equilibrium, and thermodynamics.

PubMed

Yan, Ting-guo; Wang, Li-Juan

2014-01-01

A magnetic adsorbent was synthesized by γ-aminopropyltriethoxysilane (APTES) modification of Fe(3)O(4) particles using a two-step process. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vibration sample magnetometry were used to characterize the obtained magnetic adsorbent. EDS and XPS showed that APTES polymer was successfully introduced onto the as-prepared Fe(3)O(4)/APTES particle surfaces. The saturation magnetization of the magnetic adsorbent was around 65 emu g(-1), which indicated that the dye can be removed fast and efficiently from aqueous solution with an external magnetic field. The maximum adsorption capacities of Fe(3)O(4)/APTES for C.I. Reactive Red 228 (RR 228) and Congo Red (CR) were 51.4 and 118.8 mg g(-1), respectively. The adsorption of C.I. Reactive Red 228 (RR 228) and Congo Red (CR) on Fe(3)O(4)/APTES particles corresponded well to the Langmuir model and the Freundlich model, respectively. The adsorption processes for RR 228 and CR followed the pseudo-second-order model. The Boyd's film-diffusion model showed that film diffusion also played a major role in the studied adsorption processes for both dyes. Thermodynamic study indicated that both of the adsorption processes of the two dyes are spontaneous exothermic.

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.

Fabrication of a novel NiFe2O4/Zn-Al layered double hydroxide intercalated with EDTA composite and its adsorption behavior for Cr(VI) from aqueous solution

NASA Astrophysics Data System (ADS)

Deng, Lin; Shi, Zhou; Wang, Li; Zhou, Shiqing

2017-05-01

A novel magnetic NiFe2O4/Zn-Al layered double hydroxide intercalated with EDTA composite (NiFe2O4/ZnAl-EDTA LDH) was prepared through modified coprecipitation method and employed for adsorptive removal of Cr(VI) from aqueous solution. The adsorbents were characterized using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). Factors affecting the Cr(VI) adsorption, such as initial solution pH, adsorbent dosage, contact time, initial Cr(VI) concentration, temperature and coexisting ions, were studied systematically. Experiments results show that the magnetic NiFe2O4/ZnAl-EDTA LDH exhibits high adsorption efficiency within a wide pH range of 3.0-7.0 (R>80% at Cr(VI) concentration 50 mg L-1, contact time 360 min, and adsorbent dosage 2 g/L) and quick separation property. The adsorption process is fitted well with the Langmuir isotherm and pseudo-second-order kinetic model. The maximum theoretical adsorption capacity is found to be 77.22 mg g-1 at pH 6.0 and 318 K. The positive ΔH value (2.907 kJ mol-1) and negative ΔG value (-4.722 kJ mol-1) at 298-318 K reveals that the adsorption process is feasible, spontaneous and endothermic. Coexisting anions (PO43-, SO42-, CO32-, HCO3-, Cl-, and NO3-) have no significant effect on Cr(VI) removal. The mechanism study indicates that the adsorption of Cr(VI) onto NiFe2O4/ZnAl-EDTA LDH mainly involves electrostatic attraction and ion exchange interaction. It is interesting to note that a proportion of Cr(VI) adsorbed on the adsorbent surface are reduced to Cr(III) during the adsorption process. Results from this study demonstrate the potential utility of the magnetic NiFe2O4/ZnAl-EDTA LDH that could be developed into a viable technology for efficient removal of Cr(VI) from aqueous solution.

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)

Coherent fifth-order visible-infrared spectroscopies: ultrafast nonequilibrium vibrational dynamics in solution.

PubMed

Lynch, Michael S; Slenkamp, Karla M; Cheng, Mark; Khalil, Munira

2012-07-05

Obtaining a detailed description of photochemical reactions in solution requires measuring time-evolving structural dynamics of transient chemical species on ultrafast time scales. Time-resolved vibrational spectroscopies are sensitive probes of molecular structure and dynamics in solution. In this work, we develop doubly resonant fifth-order nonlinear visible-infrared spectroscopies to probe nonequilibrium vibrational dynamics among coupled high-frequency vibrations during an ultrafast charge transfer process using a heterodyne detection scheme. The method enables the simultaneous collection of third- and fifth-order signals, which respectively measure vibrational dynamics occurring on electronic ground and excited states on a femtosecond time scale. Our data collection and analysis strategy allows transient dispersed vibrational echo (t-DVE) and dispersed pump-probe (t-DPP) spectra to be extracted as a function of electronic and vibrational population periods with high signal-to-noise ratio (S/N > 25). We discuss how fifth-order experiments can measure (i) time-dependent anharmonic vibrational couplings, (ii) nonequilibrium frequency-frequency correlation functions, (iii) incoherent and coherent vibrational relaxation and transfer dynamics, and (iv) coherent vibrational and electronic (vibronic) coupling as a function of a photochemical reaction.

Global minimum-energy structure and spectroscopic properties of I2(*-) x n H2O clusters: a Monte Carlo simulated annealing study.

PubMed

Pathak, Arup Kumar; Mukherjee, Tulsi; Maity, Dilip Kumar

2010-01-18

The vibrational (IR and Raman) and photoelectron spectral properties of hydrated iodine-dimer radical-anion clusters, I(2)(*-) x n H(2)O (n=1-10), are presented. Several initial guess structures are considered for each size of cluster to locate the global minimum-energy structure by applying a Monte Carlo simulated annealing procedure including spin-orbit interaction. In the Raman spectrum, hydration reduces the intensity of the I-I stretching band but enhances the intensity of the O-H stretching band of water. Raman spectra of more highly hydrated clusters appear to be simpler than the corresponding IR spectra. Vibrational bands due to simultaneous stretching vibrations of O-H bonds in a cyclic water network are observed for I(2)(*-) x n H(2)O clusters with n > or = 3. The vertical detachment energy (VDE) profile shows stepwise saturation that indicates closing of the geometrical shell in the hydrated clusters on addition of every four water molecules. The calculated VDE of finite-size small hydrated clusters is extrapolated to evaluate the bulk VDE value of I(2)(*-) in aqueous solution as 7.6 eV at the CCSD(T) level of theory. Structure and spectroscopic properties of these hydrated clusters are compared with those of hydrated clusters of Cl(2)(*-) and Br(2)(*-).

Vibrational spectra, optical properties, NBO and HOMO-LUMO analysis of L-Phenylalanine L-Phenylalaninium Perchlorate: DFT calculations.

PubMed

Elleuch, Nabil; Ben Ahmed, Ali; Feki, Habib; Abid, Younes; Minot, Christian

2014-01-01

In this work, we report a combined experimental and theoretical study of a nonlinear optical material, L-Phenylalanine L-Phenylalaninium Perchlorate. Single crystals of the title compound have been grown by slow evaporation of an aqueous solution at room temperature. Theoretical calculations were preceded by redetermination of the crystal X-ray structure. The compound crystallizes in the non-centro symmetric space group P2(1)2(1)2(1) of the orthorhombic system. The FT-IR and Raman spectra of the crystal were recorded and analyzed. The density functional theory (DFT) computations have been performed at B3LYP/6-31G(d) level to derive equilibrium geometry, vibrational wavenumbers, intensity and NLO properties. All observed vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our DFT calculations as a primary source of attribution and also by comparison with the previous results for similar compounds. Natural bond orbital analysis was carried out to demonstrate the various inter-and intramolecular interaction that are responsible of the stabilization of the compound. The lowering of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap appears to be the cause of its enhanced charge transfer interaction leading to high NLO activity. Copyright © 2013 Elsevier B.V. All rights reserved.

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...

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

An Attempt to Shorten Loading Time of Epirubicin into DC Beads® Using Vibration and a Sieve.

PubMed

Sonoda, Akinaga; Nitta, Norihisa; Yamamoto, Takefumi; Tomozawa, Yuki; Ohta, Shinichi; Watanabe, Shobu; Murata, Kiyoshi

2017-04-01

We investigated the possibility of shortening the time required for loading epirubicin into calibrated polyvinyl alcohol-based hydrogel beads (DC Beads ® ) to be used for transarterial chemoembolization. After separating the beads suspended in phosphate-buffered saline (PBS) solution by the use of a sieve (clearance 75 µm), epirubicin hydrochloride (EH) was loaded for 20, 30, or 60 s under vibration into DC beads. The EH loading rate into conventionally prepared (control) beads, i.e., beads loaded for 30 min without vibration, and vibration-loaded beads were calculated from the residual EH concentration in the bead-depleted EH solution. The amount of EH eluted from conventionally and vibration-loaded samples into a PBS solution (pH 7.0) was measured at 15 and 30 min and 1, 2, 6, 12, and 24 h. We also recorded the inhibitory effect of the PBS solution on the loading time. Using frozen sections, the EH load in the beads was evaluated visually under a fluorescence microscope. Spectrophotometry (495 nm) showed that the loading rate was 98.98 ± 0.34, 99.02 ± 0.32, and 99.50 ± 0.11 % with 20-, 30-, and 60-s vibration, respectively. The eluted rate was statistically similar between vibration- and statically loaded (control) beads. The PBS solution hampered EH loading into the beads. Visually, the distribution of EH in conventionally and vibration-loaded DC beads was similar. The use of vibration and the removal of PBS solution when epirubicin hydrochloride was loaded into DC beads dramatically shortened the loading time of epirubicin hydrochloride into DC beads.

Calculation of the properties of the S3- radical anion and its complexes with Cu+ in aqueous solution

NASA Astrophysics Data System (ADS)

Tossell, J. A.

2012-10-01

A species observed in aqueous sulfidic solutions at high T and P has recently been identified as the anion radical S3-, based on the Raman spectrum obtained in a hydrothermal diamond-anvil cell (Pokrovski and Dubrovinsky, 2011, Science, 331, 1052-1054). Such a species had not been expected to occur in such environments, although S3- as an component of lapis lazuli, other solids and even albite melt has been well studied (Winther et al., 1998; Reinen and Lindner, 1999; Arieli et al., 2004; Shnitko et al., 2008; Bacci et al., 2009). We have calculated the structures, energetics, vibrational and UV-visible spectra of S3- and several other similar species and confirm the species identification of Pokrovski and Dubrovinsky, although we are still somewhat concerned about the apparent lack of a third peak which we calculate to be present in the Raman spectrum of S3-. Our calculations indicate that the reaction: S6-2⇒2S3- in aqueous solution has a free energy change of +3 kcal/mol at 298 K and 1 atm pressure but -13 kcal/mol at 723 K and 1 atm pressure, consistent with the disappearance of disulfide species and the appearance of S3-at high T. Likewise, the free energy for the reaction: 2HS+SO4-2+H⇒S3-+.75O+2.5HO decreases from 44.1 to 19.0 kcal/mol between 298 and 723 K (again at 1 atm). This is consistent with the decrease in concentrations of SH- and SO4-2 and the formation of S3- observed by Pokrovski and Dubrovinski over this temperature range. The corresponding log K values are in semiquantitative agreement with those found by Pokrovski and Dubrovinsky. The main contribution to these changes in reaction free energy with temperature come from the VRT (vibrational-rotational-translational) contribution to the gas-phase free energy, while the hydration free energy difference changes little. Calculation of 34S-32S isotopic fractionations for S3- at 298 K give δ values of around +4.3% relative to H2S, a value intermediate between that of S3 and S3-2. Calculated free energies for exchange reactions between S3- and SH- establish that S3- forms complexes with Cu+ which are similar in stability to its complexes with SH-. The S3Cu(OH2) complex shows two coordination at Cu and a nearly linear

Synthesis, growth and characterization of a nonlinear optical crystal: Bis l-proline hydrogen nitrate.

PubMed

Selvaraju, K; Kirubavathi, K

2013-11-01

The single crystals of bis l-proline hydrogen nitrate (BLPHN) belonging to non-centrosymmetric space group were successfully grown by the slow evaporation solution growth technique. The BLPHN crystals of size 10×7×3mm(3) were obtained in 35days. Initially, the solubility tests were carried out for two solvents such as deionized water and mixed of deionized water-acetone. Among the two solvents, the solubility of BLPHN was found to be the highest in deionized water, so crystallization of BLPHN was done from its aqueous solution. As grown, crystals were characterized by single crystal X-ray diffraction studies and optical transmission spectral studies. Infrared spectroscopy, thermo gravimetric analysis and differential thermal analysis measurements were performed to study the molecular vibration and thermal behavior of the grown BLPHN crystals. Nonlinear optical (NLO) behavior of BLPHN crystal was studied by Kurtz and Perry powder method. Copyright © 2013 Elsevier B.V. All rights reserved.

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)

Measurements of thermodynamic and optical properties of selected aqueous organic and organic-inorganic mixtures of atmospheric relevance.

PubMed

Lienhard, Daniel M; Bones, David L; Zuend, Andreas; Krieger, Ulrich K; Reid, Jonathan P; Peter, Thomas

2012-10-11

Atmospheric aerosol particles can exhibit liquid solution concentrations supersaturated with respect to the dissolved organic and inorganic species and supercooled with respect to ice. In this study, thermodynamic and optical properties of sub- and supersaturated aqueous solutions of atmospheric interest are presented. The density, refractive index, water activity, ice melting temperatures, and homogeneous ice freezing temperatures of binary aqueous solutions containing L(+)-tartaric acid, tannic acid, and levoglucosan and ternary aqueous solutions containing levoglucosan and one of the salts NH(4)HSO(4), (NH(4))(2)SO(4), and NH(4)NO(3) have been measured in the supersaturated concentration range for the first time. In addition, the density and refractive index of binary aqueous citric acid and raffinose solutions and the glass transition temperatures of binary aqueous L(+)-tartaric acid and levoglucosan solutions have been measured. The data presented here are derived from experiments on single levitated microdroplets and bulk solutions and should find application in thermodynamic and atmospheric aerosol models as well as in food science applications.

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

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.

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.

Distribution of phospholipid based formulations in the skin investigated by combined ATR-FTIR and tape stripping experiments.

PubMed

Wolf, Martin; Halper, Maria; Pribyl, Raffaela; Baurecht, Dieter; Valenta, Claudia

2017-03-15

The spatial distribution of exogenous substances in the stratum corneum (SC) could have an influence on their skin irritation potential. In this study it was possible to monitor the distribution of phospholipids with their phosphatidylcholine scaffold on porcine ear skin by combining tape stripping and in vitro ATR-FTIR spectroscopy. Significant vibrational modes in the spectra could be successfully assigned to the functional groups of the molecules. Thus it was possible to track the phospholipids without the need of their deuterated form by calculating difference spectra from the treated - untreated skin samples. The correlation between four characteristic bands (R 2 ≥0.9909) revealed the excellent suitability of this semi-quantitative method for deep profiling analysis. The penetration capabilities of aqueous suspensions of the different phospholipid compositions as well as two monoacyl-phosphatidylcholine based liposome formulations were investigated using this method. Nevertheless, differences in the distribution of the investigated phospholipid species, having different amounts of monoacyl-phosphatidylcholine, could not be found. It could be clearly shown that the deepest skin penetration was seen in the irritating anionic SDS (sodium dodecyl sulfate) out of the aqueous solution. The aqueous suspensions based on different phospholipid surfactants showed the same range of penetration depth (10-15% of SC), whereas the smallest skin penetration depth was observed after the application of liposomal formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Vibrational relaxation of I2 in complexing solvents: The role of solvent-solute attractive forces

NASA Astrophysics Data System (ADS)

Shiang, Joseph J.; Liu, Hongjun; Sension, Roseanne J.

1998-12-01

Femtosecond transient absorption studies of I2-arene complexes, with arene=hexamethylbenzene (HMB), mesitylene (MST), or m-xylene (mX), are used to investigate the effect of solvent-solute attractive forces upon the rate of vibrational relaxation in solution. Comparison of measurements on I2-MST complexes in neat mesitylene and I2-MST complexes diluted in carbontetrachloride demonstrate that binary solvent-solute attractive forces control the rate of vibrational relaxation in this prototypical model of diatomic vibrational relaxation. The data obtained for different arenes demonstrate that the rate of I2 relaxation increases with the magnitude of the I2-arene attractive interaction. I2-HMB relaxes much faster than I2 in MST or mX. The results of these experiments are discussed in terms of both isolated binary collision and instantaneous normal mode models for vibrational relaxation.

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.

Terahertz circular dichroism spectroscopy of biomolecules

NASA Astrophysics Data System (ADS)

Xu, Jing; Galan, Jhenny; Ramian, Gerald; Savvidis, Pavlos; Scopatz, Anthony; Birge, Robert R.; Allen, S. James; Plaxco, Kevin

2004-02-01

Biopolymers such as proteins, DNA and RNA fold into large, macromolecular chiral structures. As charged macromolecules, they absorb strongly in the terahertz due to large-scale collective vibrational modes; as chiral objects, this absorption should be coupled with significant circular dichroism. Terahertz circular dichroism (TCD) is potentially important as a biospecific sensor, unobscured by spectral features related to abiological material. We have constructed atomistic simulations and elastic continuum models of TCD. These models estimate the magnitude of the TCD and the relation between TCD spectroscopic signatures (zero crossings) and the structure, charge distribution and mechanical properties of biomaterials. A broad band TCD spectrometer based on a polarizing interferometer is developed to explore TCD in biomolecules in aqueous solution. Preliminary results on TCD in lysozyme in water at several terahertz frequencies is presented.

Asymptotically Exact Solution of the Problem of Harmonic Vibrations of an Elastic Parallelepiped

NASA Astrophysics Data System (ADS)

Papkov, S. O.

2017-11-01

An asymptotically exact solution of the classical problem of elasticity about the steadystate forced vibrations of an elastic rectangular parallelepiped is constructed. The general solution of the vibration equations is constructed in the form of double Fourier series with undetermined coefficients, and an infinite system of linear algebraic equations is obtained for determining these coefficients. An analysis of the infinite system permits determining the asymptotics of the unknowns which are used to convolve the double series in both equations of the infinite systems and the displacement and stress components. The efficiency of this approach is illustrated by numerical examples and comparison with known solutions. The spectrum of the parallelepiped symmetric vibrations is studied for various ratios of its sides.

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

Sonoda, Akinaga, E-mail: akinagasonoda@yahoo.co.jp; Nitta, Norihisa; Yamamoto, Takefumi

PurposeWe investigated the possibility of shortening the time required for loading epirubicin into calibrated polyvinyl alcohol-based hydrogel beads (DC Beads{sup ®}) to be used for transarterial chemoembolization.MethodAfter separating the beads suspended in phosphate-buffered saline (PBS) solution by the use of a sieve (clearance 75 µm), epirubicin hydrochloride (EH) was loaded for 20, 30, or 60 s under vibration into DC beads. The EH loading rate into conventionally prepared (control) beads, i.e., beads loaded for 30 min without vibration, and vibration-loaded beads were calculated from the residual EH concentration in the bead-depleted EH solution. The amount of EH eluted from conventionally and vibration-loadedmore » samples into a PBS solution (pH 7.0) was measured at 15 and 30 min and 1, 2, 6, 12, and 24 h. We also recorded the inhibitory effect of the PBS solution on the loading time. Using frozen sections, the EH load in the beads was evaluated visually under a fluorescence microscope.ResultsSpectrophotometry (495 nm) showed that the loading rate was 98.98 ± 0.34, 99.02 ± 0.32, and 99.50 ± 0.11 % with 20-, 30-, and 60-s vibration, respectively. The eluted rate was statistically similar between vibration- and statically loaded (control) beads. The PBS solution hampered EH loading into the beads. Visually, the distribution of EH in conventionally and vibration-loaded DC beads was similar.DiscussionThe use of vibration and the removal of PBS solution when epirubicin hydrochloride was loaded into DC beads dramatically shortened the loading time of epirubicin hydrochloride into DC beads.« less

Biosorption of Cd+2 by green plant biomass, Araucaria heterophylla: characterization, kinetic, isotherm and thermodynamic studies

NASA Astrophysics Data System (ADS)

Sarada, B.; Krishna Prasad, M.; Kishore Kumar, K.; Murthy, Ch V. R.

2017-11-01

The present study attempted to analyze the biosorption behavior of novel biosorbent, Araucaria heterophylla (green plant) biomass, to remove Cd+2 from solutions against various parameters, i.e., initial metal ion concentration, pH, temperature, sorbent dosage and biomass particle size. The maximum biosorption was found to be 90.02% at pH 5.5 and biosorption capacity ( q e) of Cd+2 is 9.2506 mg g-1. The Langmuir and Freundlich equilibrium adsorption isotherms were studied and it was observed that Freundlich model is the best fit than the Langmuir model with correlation co-efficient of 0.999. Kinetic studies indicated that the biosorption process of Cd+2 well followed the pseudo-second-order model with R 2 0.999. Thermodynamic studies observed that the process is exothermic (Δ H ° negative). Free energy change (Δ G °) with negative sign reflected the feasibility and spontaneous nature of the process. The chemical functional -OH groups, CH2 stretching vibrations, C=O carbonyl group of alcohol, C=O carbonyl group of amide, P=O stretching vibrations and -CH groups were involved in the biosorption process. The XRD pattern of the A. heterophylla was found to be mostly amorphous in nature. The SEM studies showed Cd+2 biosorption on selective grains of the biosorbent. It was concluded that A. heterophylla leaf powder can be used as an effective, low-cost, and environmentally friendly biosorbent for the removal of Cd+2 from aqueous solution.

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/.

Reorientation of the ‘free OH’ group in the top-most layer of air/water interface of sodium fluoride aqueous solution probed with sum-frequency generation vibrational spectroscopy

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

Feng, Ran-Ran; Guo, Yuan; Wang, Hongfei

2014-09-17

Many experimental and theoretical studies have established the specific anion, as well as cation effects on the hydrogen-bond structures at the air/water interface of electrolyte solutions. However, the ion effects on the top-most layer of the air/water interface, which is signified by the non-hydrogen-bonded so-called ‘free O-H’ group, has not been discussed or studied. In this report, we present the measurement of changes of the orientational angle of the ‘free O-H’ group at the air/water interface of the sodium fluoride (NaF) solutions at different concentrations using the interface selective sum-frequency generation vibrational spectroscopy (SFG-VS) in the ssp and ppp polarizations.more » The polarization dependent SFG-VS results show that the average tilt angle of the ‘free O-H’ changes from about 35.3 degrees ± 0.5 degrees to 43.4 degrees ± 2.1degrees as the NaF concentration increase from 0 to 0.94M (nearly saturated). Such tilt angle change is around the axis of the other O-H group of the same water molecule at the top-most layer at the air/water interface that is hydrogen-bonded to the water molecules below the top-most layer. These results provide quantitative molecular details of the ion effects of the NaF salt on the structure of the water molecules at the top-most layer of the air/water interfacial, even though both the Na+ cation and the F- anion are believed to be among the most excluded ions from the air/water interface.« less

Dispersed three-pulse infrared photon echoes of nitrous oxide in water and octanol.

PubMed

Shattuck, J T; Schneck, J R; Chieffo, L R; Erramilli, S; Ziegler, L D

2013-12-12

Dispersed IR three-pulse photon echoes due to the antisymmetric (ν3) stretch mode of N2O dissolved in H2O and 1-octanol at room temperature are reported and analyzed. The experimentally determined transition frequency-frequency correlation function (FFCF) in these two solvents is explained in terms of inertial solvent contributions, hydrogen bond network fluctuations, and, for octanol, the motions of the alkyl chains. The H2O hydrogen bond fluctuations result in 1.5 ps FFCF decay, in agreement with relaxation rates determined from photon echo based measurements of other aqueous solutions including salt solutions. In octanol, hydrogen bond fluctuations decay on a slower time scale of 3.3 ps and alkyl chain motions result in an inhomogeneous broadening contribution to the ν3 absorption spectrum that decays on a 35 ps time scale. Rotational reorientation of N2O is nearly 3 times faster in octanol as compared to water. Although the vibrational ν3 N2O absorption line shapes in water and octanol are similar, the line widths result from different coherence loss mechanisms. A hot band contribution in the N2O in octanol solution is found to have a significant effect on the echo spectrum due to its correspondingly stronger transition moment than that of the fundamental transition. The dephasing dynamics of the N2O ν3 stretch mode is of interest as a probe in ultrafast studies of complex or nanoconfined systems with both hydrophobic and hydrophilic regions such as phospholipids, nucleic acids, and proteins. These results demonstrate the value of the N2O molecule to act as a reporter of equilibrium fluctuations in such complex systems particularly due to its solubility characteristics and long vibrational lifetime.

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.

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

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.

Spectroscopic analysis of the powdery complex chitosan-iodine

NASA Astrophysics Data System (ADS)

Gegel, Natalia O.; Babicheva, Tatyana S.; Belyakova, Olga A.; Lugovitskaya, Tatyana N.; Shipovskaya, Anna B.

2018-04-01

A chitosan-iodine complex was obtained by modification of polymer powder in the vapor of an iodine-containing sorbate and studied by electron and IR spectroscopy, optical rotation dispersion. It was found that the electronic spectra of an aqueous solution of the modified chitosan (the source one and that stored for a year) showed intense absorption bands of triiodide and iodate ions, and also polyiodide ions, bound to the macromolecule by exciton bonding with charge transfer. Analysis of the IR spectra shows destruction of the network of intramolecular and intermolecular hydrogen bonds in the iodinated chitosan powder in comparison with the source polymer and the formation of a new chemical substance. E.g., the absorption band of deformation vibrations of the hydroxyl group disappears in the modified sample, and that of the protonated amino group shifts toward shorter wavelengths. The intensity of the stretching vibration band of the glucopyranose ring atoms significantly reduces. Heating of the modified sample at a temperature below the thermal degradation point of the polymer leads to stabilization of the chitosan-iodine complex. Based on our studies, the hydroxyl and amino groups of the aminopolysaccharide have been recognized as the centers of retention of polyiodide chains in the chitosan matrix.

Synthesis and characterization of struvite nano particles

NASA Astrophysics Data System (ADS)

Rathod, K. R.; Jogiya, B. V.; Chauhan, C. K.; Joshi, M. J.

2015-06-01

Struvite, Ammonium Magnesium Phosphate Hexahydrate [(AMPH) - (NH4)MgPO4.6(H2O)], is one of the fascinating inorganic phosphate minerals. Struvite is one of the components of the urinary stones. Struvite occurs as crystallites in urine and grows as a type of kidney stone. In this study, struvite nano particles were synthesized by wet chemical technique. The aqueous solutions containing dissolved Mg(CH3COO)2.4H2O and (NH4)H2PO4 mixed at the Mg/P molar ratio of 1.00. The synthesized struvite nano particles were characterized by XRD, FT-IR, Thermal Analysis and TEM. From XRD, crystal structure of the nano particle was found to be orthorhombic and crystalline size was found to be within 11 to 26 nm. The FT-IR spectrum for the struvite nano particles confirmed the presence of a water molecule and metal-oxygen stretching vibration, O-H stretching and bending, N-H bending and stretching, P-O bending and stretching vibrations. The Thermal Analysis was carried out from room temperature to 900°C. From TEM analysis, particle size was 23 to 30 nm. All the results were compared with bulk struvite.

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.

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.

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.

[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.

A quantum-mechanics molecular-mechanics scheme for extended systems

NASA Astrophysics Data System (ADS)

Hunt, Diego; Sanchez, Veronica M.; Scherlis, Damián A.

2016-08-01

We introduce and discuss a hybrid quantum-mechanics molecular-mechanics (QM-MM) approach for Car-Parrinello DFT simulations with pseudopotentials and planewaves basis, designed for the treatment of periodic systems. In this implementation the MM atoms are considered as additional QM ions having fractional charges of either sign, which provides conceptual and computational simplicity by exploiting the machinery already existing in planewave codes to deal with electrostatics in periodic boundary conditions. With this strategy, both the QM and MM regions are contained in the same supercell, which determines the periodicity for the whole system. Thus, while this method is not meant to compete with non-periodic QM-MM schemes able to handle extremely large but finite MM regions, it is shown that for periodic systems of a few hundred atoms, our approach provides substantial savings in computational times by treating classically a fraction of the particles. The performance and accuracy of the method is assessed through the study of energetic, structural, and dynamical aspects of the water dimer and of the aqueous bulk phase. Finally, the QM-MM scheme is applied to the computation of the vibrational spectra of water layers adsorbed at the TiO2 anatase (1 0 1) solid-liquid interface. This investigation suggests that the inclusion of a second monolayer of H2O molecules is sufficient to induce on the first adsorbed layer, a vibrational dynamics similar to that taking place in the presence of an aqueous environment. The present QM-MM scheme appears as a very interesting tool to efficiently perform molecular dynamics simulations of complex condensed matter systems, from solutions to nanoconfined fluids to different kind of interfaces.

A quantum-mechanics molecular-mechanics scheme for extended systems.

PubMed

Hunt, Diego; Sanchez, Veronica M; Scherlis, Damián A

2016-08-24

We introduce and discuss a hybrid quantum-mechanics molecular-mechanics (QM-MM) approach for Car-Parrinello DFT simulations with pseudopotentials and planewaves basis, designed for the treatment of periodic systems. In this implementation the MM atoms are considered as additional QM ions having fractional charges of either sign, which provides conceptual and computational simplicity by exploiting the machinery already existing in planewave codes to deal with electrostatics in periodic boundary conditions. With this strategy, both the QM and MM regions are contained in the same supercell, which determines the periodicity for the whole system. Thus, while this method is not meant to compete with non-periodic QM-MM schemes able to handle extremely large but finite MM regions, it is shown that for periodic systems of a few hundred atoms, our approach provides substantial savings in computational times by treating classically a fraction of the particles. The performance and accuracy of the method is assessed through the study of energetic, structural, and dynamical aspects of the water dimer and of the aqueous bulk phase. Finally, the QM-MM scheme is applied to the computation of the vibrational spectra of water layers adsorbed at the TiO2 anatase (1 0 1) solid-liquid interface. This investigation suggests that the inclusion of a second monolayer of H2O molecules is sufficient to induce on the first adsorbed layer, a vibrational dynamics similar to that taking place in the presence of an aqueous environment. The present QM-MM scheme appears as a very interesting tool to efficiently perform molecular dynamics simulations of complex condensed matter systems, from solutions to nanoconfined fluids to different kind of interfaces.

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.

Multivariate frequency domain analysis of protein dynamics

NASA Astrophysics Data System (ADS)

Matsunaga, Yasuhiro; Fuchigami, Sotaro; Kidera, Akinori

2009-03-01

Multivariate frequency domain analysis (MFDA) is proposed to characterize collective vibrational dynamics of protein obtained by a molecular dynamics (MD) simulation. MFDA performs principal component analysis (PCA) for a bandpass filtered multivariate time series using the multitaper method of spectral estimation. By applying MFDA to MD trajectories of bovine pancreatic trypsin inhibitor, we determined the collective vibrational modes in the frequency domain, which were identified by their vibrational frequencies and eigenvectors. At near zero temperature, the vibrational modes determined by MFDA agreed well with those calculated by normal mode analysis. At 300 K, the vibrational modes exhibited characteristic features that were considerably different from the principal modes of the static distribution given by the standard PCA. The influences of aqueous environments were discussed based on two different sets of vibrational modes, one derived from a MD simulation in water and the other from a simulation in vacuum. Using the varimax rotation, an algorithm of the multivariate statistical analysis, the representative orthogonal set of eigenmodes was determined at each vibrational frequency.

Investigate the ultrasound energy assisted adsorption mechanism of nickel(II) ions onto modified magnetic cobalt ferrite nanoparticles: Multivariate optimization.

PubMed

Mehrabi, Fatemeh; Alipanahpour Dil, Ebrahim

2017-07-01

In present study, magnetic cobalt ferrite nanoparticles modified with (E)-N-(2-nitrobenzylidene)-2-(2-(2-nitrophenyl)imidazolidine-1-yl) ethaneamine (CoFe 2 O 4 -NPs-NBNPIEA) was synthesized and applied as novel adsorbent for ultrasound energy assisted adsorption of nickel(II) ions (Ni 2+ ) from aqueous solution. The prepared adsorbent characterized by Fourier transforms infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). The dependency of adsorption percentage to variables such as pH, initial Ni 2+ ions concentration, adsorbent mass and ultrasound time were studied with response surface methodology (RSM) by considering the desirable functions. The quadratic model between the dependent and independent variables was built. The proposed method showed good agreement between the experimental data and predictive value, and it has been successfully employed to adsorption of Ni 2+ ions from aqueous solution. Subsequently, the experimental equilibrium data at different concentration of Ni 2+ ions and 10mg amount of adsorbent mass was fitted to conventional isotherm models like Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich and it was revealed that the Langmuir is best model for explanation of behavior of experimental data. In addition, conventional kinetic models such as pseudo-first and second-order, Elovich and intraparticle diffusion were applied and it was seen that pseudo-second-order equation is suitable to fit the experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Ab initio study of the structural properties of ascorbic acid (vitamin C)

NASA Astrophysics Data System (ADS)

Allen, Reeshemah N.; Shukla, M. K.; Reed, Demarcio; Leszczynski, Jerzy

Geometries of the neutral and ionic tautomeric species of ascorbic acid were optimized at the density functional theory (DFT) level using the B3LYP functional. The radical species were evaluated using the unrestricted B3LYP method. Single-point energy calculations were also performed using the Møller-Plesset (MP2) and unrestricted MP2 (UMP2) methods for the closed-shell and open-shell systems, respectively. The effects of aqueous solution were evaluated using the conducting polarized continuum model (CPCM) and polarized continuum model (PCM). The geometries of most stable radicals in the respective groups were also optimized in the water solution using the CPCM model at the UB3LYP level. All calculation were performed using the 6-311++G(d,p) basis set. The nature of stationary points on the gas phase potential energy surfaces (PESs) was evaluated using vibrational frequency calculations; all geometries characterize local minima. The species obtained by the deprotonation of the O3 site is the most stable monoanion of ascorbic acid. For the radical species, the structure obtained by the dehydrogenation of the O3 site is the most stable monoradical. Among the radical anions, the species obtained by the deprotonation of the O3 site and subsequent dehydrogenation of the O2 site is the most stable in the gas phase and in an aqueous medium. The computed isotropic hyperfine coupling constants of this species were found to be in good agreement with the experimental data. Our investigation also supports the earlier findings that the oxidized species of ascorbic acid in water solution by the OH? radical is radical anion of the AAO?3O-2 form. The spin densities and molecular electrostatic potentials are also discussed.

An effective way to reduce water absorption to terahertz

NASA Astrophysics Data System (ADS)

Wu, Yaxiong; Su, Bo; He, Jingsuo; Zhang, Cong; Zhang, Hongfei; Zhang, Shengbo; Zhang, Cunlin

2018-01-01

Since many vibrations and rotational levels of biomolecules fall within the THz band, THz spectroscopy can be used to identify biological samples. In addition, most biomolecules need to maintain their biological activity in a liquid environment, but water as polar substance has strong absorption to the THz wave. Thus, it is difficult to detect the sample information in aqueous solution using THz wave. In order to prevent the information of biological samples were masked in the solution, many research methods were used to explore how to reduce the water absorption of terahertz. In this paper, we have developed a real-time chemical methodology through transmission Terahertz time-domain spectroscopy (THz-TDS) system. The material of Zeonor 1020r is used as substrate and cover plate, and PDMS as channel interlayer. The transmission of the empty microfluidic chip is more than 80% in the range of 0.2-2.6 THz by THz-TDS system. Then, experiments were carried out using chips, which were filled with different volumes of 1, 2- propanediol, and it has been proved that the microfluidic chip could reduce the water absorption of terahertz. Finally, in order to further explore the reduction of terahertz to water absorption, we inject different concentrations of electrolyte to the chip. The results show that with the addition of different electrolytes, terahertz transmission line has evident changes. It can be taken into account that the electrolyte has different effects about the hydrogen bonds in the aqueous solution. Some of them can promote water molecules clusters, while others destroy them. Based on the basis of microfluidic chip, the discovery of this phenomenon can provide a way that reduces water absorption of terahertz. This work has laid a solid foundation for the subsequent study in reducing water absorption of terahertz.

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.

Hydrogen bonding in hydrates with one acetic acid molecule.

PubMed

Pu, Liang; Sun, Yueming; Zhang, Zhibing

2010-10-14

Hydrogen bonding (H-bond) interaction significantly influences the separation of acetic acid (HAc) from the HAc/H(2)O mixtures, especially the dilute solution, in distillation processes. It has been examined from the HAc mono-, di-, tri-, and tetrahydrates by analyzing the structures, binding energies, and infrared vibrational frequencies from quantum chemical calculations. For the first coordinate shell the 6-membered head-on ring is surely the most favorable structure because it has (1) the most favorable H-bonding parameters, (2) almost the largest binding energy per H-bond, (3) the biggest wavenumber shifts, and (4) the highest ring distribution (the AIMD simulations). Moreover, the comparison of the calculations with the experiments (the X-ray scattering data and IR frequencies) suggests that the possible structures in dilute aqueous solution are those involving two or more coordinate shells. The H-bonding in these water-surrounded HAc hydrates are the origin of the low-efficiency problem of isolating HAc from the dilute HAc/H(2)O mixtures. It is apparently a tougher work to break the H-bonds among HAc and the surrounded H(2)O molecules with respect to the case of more concentrated solutions, where the dominant structures are HAc or H(2)O aggregates.

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.

The spectroscopic study of building composites containing natural sorbents.

PubMed

Król, M; Mozgawa, W

2011-08-15

This work presents the results of FT-IR spectroscopic studies of heavy metal cations (Ag(+), Pb(2+), Zn(2+), Cd(2+) and Cr(3+)) immobilization from aqueous solutions on natural sorbents. The sorption has been conducted on sodium forms of zeolite (clinoptilolite) and clay minerals (mixtures containing mainly montmorillonite and kaolinite) which have been separated from natural Polish deposit. In the next part of the work both sorbents were used to obtain new building composites. It was proven those heavy metal cations' sorption causes changes in IR spectra of the zeolite and clay minerals. These alterations are dependent on the way the cations were sorbed. In the case of zeolite, variations of the bands corresponding to the characteristic ring vibrations have been observed. These rings occur in pseudomolecular complexes 4-4-1 (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. The most significant changes have been determined in the region of pseudolattice vibrations (650-700 cm(-1)). In the instance of clay minerals, changes in the spectra occur at two ranges: 1200-800 cm(-1)--the range of the bands assigned to asymmetric Si-O(Si,Al) and bending Al-OH vibrations and 3800-3000 cm(-1)--the range of the bands originating from OH(-) groups stretching vibrations. Next results indicate possibilities of applying the used natural sorbents for the obtainment of new building materials having favourable composition and valuable properties. The zeolite was used for obtaining autoclaved materials with an addition of CaO, and the clay minerals for ceramic sintered materials with an addition of quartz and clinoptilolite were produced. FT-IR studies were also conducted on the obtained materials. Copyright © 2010 Elsevier B.V. All rights reserved.

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

Anodic electrodeposition of NiTSPP from aqueous basic media.

PubMed

Pérez-Morales, Marta; Muñoz, Eulogia; Martín-Romero, María T; Camacho, Luis

2005-06-07

The oxidative electrodeposition of NiTSPP (tetrakis(4-sulfonatophenyl) Ni porphyrin) on ITO electrode from 0.1 M NaOH aqueous solution has been studied, and UV-visible and reflection FTIR spectroscopies have been used to analyze the composition of such film. By use of UV-vis spectroscopy, small absorbance of the film and an almost nulling effect on the Soret band of the porphyrin along the Ni(III)/Ni(II) redox process were observed. The reflection FTIR spectroscopy detected the presence of Ni-OH groups in the reduced film and as well the state of the porphyrin molecules as radical cation. Moreover, the porphyrin has been quantified by means of the area of the vibration bands assigned to the sulfonate groups by using as reference a Langmuir-Blodgett film containing a known surface concentration of NiTSPP. These results lead us propose the formation of a conductor salt by electrocrystallization, with stoichiometries TSPP/Ni(II)(OH)2 and TSPP/Ni(III)OOH, for its reduced and oxidized forms, respectively. In these two forms, the porphyrin rings will be present as radical cation, which may be stabilized through its dimerization or polymerization.

Analytical Solution for the Free Vibration Analysis of Delaminated Timoshenko Beams

PubMed Central

Abedi, Maryam

2014-01-01

This work presents a method to find the exact solutions for the free vibration analysis of a delaminated beam based on the Timoshenko type with different boundary conditions. The solutions are obtained by the method of Lagrange multipliers in which the free vibration problem is posed as a constrained variational problem. The Legendre orthogonal polynomials are used as the beam eigenfunctions. Natural frequencies and mode shapes of various Timoshenko beams are presented to demonstrate the efficiency of the methodology. PMID:24574879

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/.

Vibrational Spectroscopy of CO2- Radical Anion in Water

NASA Astrophysics Data System (ADS)

Janik, Ireneusz; Tripathi, G. N. R.

2016-06-01

The reductive conversion of CO2 into industrial products (e.g., oxalic acid, formic acid, and methanol) can occur via aqueous CO2- as a transient intermediate. While the formation, structure and reaction pathways of this radical anion have been modelled for decades using various spectroscopic and theoretical approaches, we present here, for the first time, a vibrational spectroscopic investigation in liquid water, using pulse radiolysis time-resolved resonance Raman spectroscopy for its preparation and observation. Excitation of the radical in resonance with its 235 nm absorption displays a transient Raman band at 1298 wn, attributed to the symmetric CO stretch, which is at 45 wn higher frequency than in inert matrices. Isotopic substitution at C (13CO2-) shifts the frequency downwards by 22 wn which confirms its origin and the assignment. A Raman band of moderate intensity compared to the stronger 1298 wn band also appears at 742 wn, and is assignable to the OCO bending mode. A reasonable resonance enhancement of this mode is possible only in a bent CO2-(C2v/Cs) geometry. These resonance Raman features suggest a strong solute-solvent interaction, the water molecules acting as constituents of the radical structure, rather than exerting a minor solvent perturbation. However, there is no evidence of the non-equivalence (Cs) of the two CO bonds. A surprising resonance Raman feature is the lack of overtones of the symmetric CO stretch, which we interpret due to the detachment of the electron from the CO2- moiety towards the solvation shell. Electron detachment occurs at the energies of 0.28+/-0.03 eV or higher with respect to the zero point energy of the ground electronic state. The issue of acid-base equilibrium of the radical which has been in contention for decades, as reflected in a wide variation in the reported pKa (-0.2 to 3.9), has been resolved. A value of 3.4+/-0.2 measured in this work is consistent with the vibrational properties, bond structure and charge distribution in aqueous CO2-.

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.

Mechanism of Interaction between the General Anesthetic Halothane and a Model Ion Channel Protein, II: Fluorescence and Vibrational Spectroscopy Using a Cyanophenylalanine Probe

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

Liu, J.; Strzalka, J; Tronin, A

2009-01-01

We demonstrate that cyano-phenylalanine (PheCN) can be utilized to probe the binding of the inhalational anesthetic halothane to an anesthetic-binding, model ion channel protein hbAP-PheCN. The Trp to PheCN mutation alters neither the a-helical conformation nor the 4-helix bundle structure. The halothane binding properties of this PheCN mutant hbAP-PheCN, based on fluorescence quenching, are consistent with those of the prototype, hbAP1. The dependence of fluorescence lifetime as a function of halothane concentration implies that the diffusion of halothane in the nonpolar core of the protein bundle is one-dimensional. As a consequence, at low halothane concentrations, the quenching of the fluorescencemore » is dynamic, whereas at high concentrations the quenching becomes static. The 4-helix bundle structure present in aqueous detergent solution and at the air-water interface, is preserved in multilayer films of hbAP-PheCN, enabling vibrational spectroscopy of both the protein and its nitrile label (-CN). The nitrile groups' stretching vibration band shifts to higher frequency in the presence of halothane, and this blue-shift is largely reversible. Due to the complexity of this amphiphilic 4-helix bundle model membrane protein, where four PheCN probes are present adjacent to the designed cavity forming the binding site within each bundle, all contributing to the infrared absorption, molecular dynamics (MD) simulation is required to interpret the infrared results. The MD simulations indicate that the blue-shift of -CN stretching vibration induced by halothane arises from an indirect effect, namely an induced change in the electrostatic protein environment averaged over the four probe oscillators, rather than a direct interaction with the oscillators. hbAP-PheCN therefore provides a successful template for extending these investigations of the interactions of halothane with the model membrane protein via vibrational spectroscopy, using cyano-alanine residues to form the anesthetic binding cavity.« less

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.

Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH.

PubMed

Walrafen, George E; Douglas, Rudolph T W

2006-03-21

High-temperature, high-pressure Raman spectra were obtained from aqueous NaOH solutions up to 2NaOHH2O, with X(NaOH)=0.667 at 480 K. The spectra corresponding to the highest compositions, X(NaOH)> or =0.5, are dominated by H3O2-. An IR xi-function dispersion curve for aqueous NaOH, at 473 K and 1 kbar, calculated from the data of Franck and Charuel indicates that the OH- ion forms H3O2- by preferential H bonding with nonhydrogen-bonded OH groups. Raman spectra from wet to anhydrous, solid LiOH, NaOH, and KOH yield sharp, symmetric OH- stretching peaks at 3664, 3633, and 3596 cm(-1), respectively, plus water-related, i.e., H3O2-, peaks near LiOH, 3562 cm(-1), NaOH, 3596 cm(-1), and, KOH, 3500 cm(-1). Absence of H3O2- peaks from the solid assures that the corresponding melt is anhydrous. Raman spectra from the anhydrous melts yield OH- stretching peak frequencies: LiOH, 3614+/-4 cm(-1), 873 K; NaOH, 3610+/-2 cm(-1), 975 K; and, KOH, 3607+/-2 cm(-1), 773 K, but low-frequency asymmetry due to ion-pair interactions is present which is centered near 3550 cm(-1). The ion-pair-related asymmetry corresponds to the sole IR maximum near 3550 cm(-1) from anhydrous molten NaOH, at 623 K. Bose-Einstein correction of published low-frequency Raman data from molten LiOH revealed an acoustic phonon, near 205 cm(-1), related to restricted translation of OH- versus Li+, and an optical phonon, at 625 cm(-1) and tau approximately 0.05 ps, due to protonic precession and/or pendular motion. Strong H bonding between water and the O atom of OH- forms H3O2-, but the proton of OH- does not bond with H significantly. Large Raman bandwidths (aqueous solutions) are explained in terms of inhomogeneous broadening due to proton transfer in a double well. Vibrational assignments are presented for H3O2-.

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.

Interplay of stereoelectronic and enviromental effects in tuning the structural and magnetic properties of a prototypical spin probe: further insights from a first principle dynamical approach.

PubMed

Pavone, Michele; Cimino, Paola; De Angelis, Filippo; Barone, Vincenzo

2006-04-05

The nitrogen isotropic hyperfine coupling constant (hcc) and the g tensor of a prototypical spin probe (di-tert-butyl nitroxide, DTBN) in aqueous solution have been investigated by means of an integrated computational approach including Car-Parrinello molecular dynamics and quantum mechanical calculations involving a discrete-continuum embedding. The quantitative agreement between computed and experimental parameters fully validates our integrated approach. Decoupling of the structural, dynamical, and environmental contributions acting onto the spectral observables allows an unbiased judgment of the role played by different effects in determining the overall experimental observables and highlights the importance of finite-temperature vibrational averaging. Together with their intrinsic interest, our results pave the route toward more reliable interpretations of EPR parameters of complex systems of biological and technological relevance.

Femtosecond x-ray scattering study of ultrafast photoinduced structural dynamics in solvated [ Co ( terpy ) 2 ] 2 +

DOE PAGES

Biasin, Elisa; van Driel, Tim Brandt; Kjær, Kasper S.; ...

2016-06-30

Here, we study the structural dynamics of photoexcited [Co(terpy) 2] 2+ in an aqueous solution with ultrafast x-ray diffuse scattering experiments conducted at the Linac Coherent Light Source. Through direct comparisons with density functional theory calculations, our analysis shows that the photoexcitation event leads to elongation of the Co-N bonds, followed by coherent Co-N bond length oscillations arising from the impulsive excitation of a vibrational mode dominated by the symmetrical stretch of all six Co-N bonds. This mode has a period of 0.33 ps and decays on a subpicosecond time scale. We find that the equilibrium bond-elongated structure of themore » high spin state is established on a single-picosecond time scale and that this state has a lifetime of ~7 ps.« less

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.

Aspheric Solute Ions Modulate Gold Nanoparticle Interactions in an Aqueous Solution: An Optimal Way to Reversibly Concentrate Functionalized Nanoparticles

PubMed Central

Villarreal, Oscar D; Chen, Liao Y; Whetten, Robert L; Demeler, Borries

2015-01-01

Nanometer-sized gold particles (AuNPs) are of peculiar interest because their behaviors in an aqueous solution are sensitive to changes in environmental factors including the size and shape of the solute ions. In order to determine these important characteristics, we performed all-atom molecular dynamics simulations on the icosahedral Au144 nanoparticles each coated with a homogeneous set of 60 thiolates (4-mercapto-benzoate, pMBA) in eight aqueous solutions having ions of varying sizes and shapes (Na+, K+, tetramethylamonium cation TMA+, trisamonium cation TRS+, Cl−, and OH−). For each solution, we computed the reversible work (potential of mean of force) to bring two nanoparticles together as a function of their separation distance. We found that the behavior of pMBA protected Au144 nanoparticles can be readily modulated by tuning their aqueous environmental factors (pH and solute ion combinations). We examined the atomistic details on how the sizes and shapes of solute ions quantitatively factor in the definitive characteristics of nanoparticle-environment and nanoparticle-nanoparticle interactions. We predict that tuning the concentrations of non-spherical composite ions such as TRS+ in an aqueous solution of AuNPs be an effective means to modulate the aggregation propensity desired in biomedical and other applications of small charged nanoparticles. PMID:26581232

Aspheric Solute Ions Modulate Gold Nanoparticle Interactions in an Aqueous Solution: An Optimal Way To Reversibly Concentrate Functionalized Nanoparticles.

PubMed

Villarreal, Oscar D; Chen, Liao Y; Whetten, Robert L; Demeler, Borries

2015-12-17

Nanometer-sized gold particles (AuNPs) are of peculiar interest because their behaviors in an aqueous solution are sensitive to changes in environmental factors including the size and shape of the solute ions. In order to determine these important characteristics, we performed all-atom molecular dynamics simulations on the icosahedral Au144 nanoparticles each coated with a homogeneous set of 60 thiolates (4-mercaptobenzoate, pMBA) in eight aqueous solutions having ions of varying sizes and shapes (Na(+), K(+), tetramethylamonium cation TMA(+), tris-ammonium cation TRS(+), Cl(-), and OH(-)). For each solution, we computed the reversible work (potential of mean of force) to bring two nanoparticles together as a function of their separation distance. We found that the behavior of pMBA protected Au144 nanoparticles can be readily modulated by tuning their aqueous environmental factors (pH and solute ion combinations). We examined the atomistic details on how the sizes and shapes of solute ions quantitatively factor in the definitive characteristics of nanoparticle-environment and nanoparticle-nanoparticle interactions. We predict that tuning the concentrations of nonspherical composite ions such as TRS(+) in an aqueous solution of AuNPs be an effective means to modulate the aggregation propensity desired in biomedical and other applications of small charged nanoparticles.

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.

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.

EDTA functionalized magnetic nanoparticle as a multifunctional adsorbent for Congo red dye from contaminated water

NASA Astrophysics Data System (ADS)

Sahoo, Jitendra Kumar; Rath, Juhi; Dash, Priyabrat; Sahoo, Harekrushna

2017-05-01

The present work reports the applicability of magnetite iron nanoparticles (Fe3O4) functionalized with ethylenediaminetetraacetic acid (EDTA) as an efficient adsorbent for the removal of Congo red (CR) dye from contaminated water. Magnetic nanoparticles (Fe3O4) are prepared by chemical precipitation method in which Fe2+ and Fe3+ salt from aqueous solution were reacted in presence of ammonia solution. The surface of Fe3O4 nanoparticle was first coated with (3-aminopropyl) triethoxy silane (APTES) by a salinization reaction and then linked with EDTA via reaction between -NH2 and -COOH to form well dispersed surface functionalised biocompatible magnetic nanoparticles. The obtained EDTA functionalized magnetic nanoparticles are characterized in terms of their morphological, XRD, BET surface area analysis, Fourier transform infrared spectroscopy (FT-IR) and Vibrating sample magnetometer (VSM). The adsorption of CR on Fe3O4-APTES-EDTA nanocomposite corresponds well to the Langmuir model and the Freundlich model respectively. The adsorption processes for CR followed the pseudo-second-order model.

Growth, structural, optical, piezoelectric and etching analysis of L-lysine p-nitrophenolate monohydrate single crystals

NASA Astrophysics Data System (ADS)

Alexandar, A.; Lakshmanan, A.; Sakthy Priya, S.; Surendran, P.; Rameshkumar, P.

2017-09-01

Nonlinear optical single crystals of L-lysine p-nitrophenolate monohydrate (LLPNP) were grown in aqueous solution by the slow evaporation solution technique (SEST). The grown crystals were subjected to powder X-ray diffraction analysis, (PXRD) and it was found that the title compound was crystallized in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The vibrational frequencies of various functional groups present in the crystal were analyzed using the FTIR spectrum with a wavenumber range between 450 cm-1 and 4000 cm-1. The microhardness analysis of the sample revealed that the crystal belongs to the soft material category. Piezoelectric analysis was performed to measure the value of the piezoelectric (d33) coefficient. Blue light emission of the material was confirmed using the photoluminescence spectrum. Thermal stability of the grown crystal was analyzed using a melting point apparatus and it was found that the LLPNP is stable upto 175∘C. Etching analysis was performed at various durations, in order to identify the surface properties of the LLPNP crystal.

A QM/MM study of the absorption spectrum of harmane in water solution and interacting with DNA: the crucial role of dynamic effects.

PubMed

Etienne, Thibaud; Very, Thibaut; Perpète, Eric A; Monari, Antonio; Assfeld, Xavier

2013-05-02

We present a time-dependent density functional theory computation of the absorption spectra of one β-carboline system: the harmane molecule in its neutral and cationic forms. The spectra are computed in aqueous solution. The interaction of cationic harmane with DNA is also studied. In particular, the use of hybrid quantum mechanics/molecular mechanics methods is discussed, together with its coupling to a molecular dynamics strategy to take into account dynamic effects of the environment and the vibrational degrees of freedom of the chromophore. Different levels of treatment of the environment are addressed starting from purely mechanical embedding to electrostatic and polarizable embedding. We show that a static description of the spectrum based on equilibrium geometry only is unable to give a correct agreement with experimental results, and dynamic effects need to be taken into account. The presence of two stable noncovalent interaction modes between harmane and DNA is also presented, as well as the associated absorption spectrum of harmane cation.

Crystal growth, structural, optical, spectral and thermal studies of tris( L-phenylalanine) L-phenylalaninium nitrate: A new organic nonlinear optical material

NASA Astrophysics Data System (ADS)

Prakash, M.; Geetha, D.; Lydia Caroline, M.

2011-10-01

Tris( L-phenylalanine) L-phenylalaninium nitrate, C 9H 12NO 2+·NO 3-·3C 9H 11NO 2 (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG.

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.

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.

Application of Porous Polydimethylsiloxane (PDMS) in oil absorption

NASA Astrophysics Data System (ADS)

Norfatriah, Abdullah; Syamaizar, Ahmad Sabli Ahmad; Samah Zuruzi, Abu

2018-04-01

Porous polydimethysiloxane (PDMS) displays both hydrophobic and oleophilic behaviour which makes it a suitable material to absorb oil in an aqueous stream. Furthermore, its elastomeric nature means that porous PDMS can be a reusable sorbent for oil. For such application, porous PDMS has to (i) absorb oil from aqueous stream quickly and (ii) discharge oil rapidly when compressed. In this study, porous polydimethylsiloxane (PDMS) has been fabricated using sugar templating method. The ability of porous PDMS to absorb olive, sunflower and vegetable oils with and without vibration was investigated. Small amplitude vibration was found to accelerate the oil uptake process and accelerates the absorption of olive and vegetable oil by 2.5 and 3 times, respectively. Compressive stress-strain curves over compression rates between 2 and 100 mm per min are similar and indicate mechanical property of porous PDMS does not vary significantly and can be rapidly compressed.

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.

Transverse vibration of a simply supported beam with symmetric overhang of arbitrary length

Treesearch

J. F. Murphy

1997-01-01

The numerical solution to the frequency equation for the transverse vibration of a simple beam with symmetric overhang is found. The numerical results converge to the analytical solutions for the two limiting cases of a beam with no overhang and a beam with no span and agree with the case in which the supports are at the nodal points of a freely vibrating beam. An...

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.

In-situ Raman spectroscopic study of aluminate speciation in H2O-KOH solutions at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Mookherjee, M.; Keppler, H.; Manning, C. E.

2009-12-01

The solubility of corundum in H2O is low even at high pressure and temperatures. Therefore, it is commonly assumed that alumina remains essentially immobile during fluid-rock interaction. However, field and experimental evidence suggests that alumina solubility is strongly enhanced in the presence of silica as well as in alkaline solutions. In order to understand what controls the alumina solubility and how it is enhanced as a function of fluid composition, we conducted Raman-spectroscopic study of Al speciation in aqueous fluids at high pressure and temperature. Experiments were carried out in an externally heated hydrothermal diamond-anvil cell equipped with low-fluorescence diamonds and iridium gaskets. Raman spectra were collected with a Horiba Jobin-Yvon Labram HR spectrometer using the 514 nm line of an argon laser for excitation. In a first series of experiments, the speciation of alumina was studied in a 1 M KOH solution in equilibrium with corundum up to 700 oC and ~1 GPa. The Raman spectra show a prominent band at 618 cm-1 interpreted to arise from Al-O stretching vibrations associated with the tetrahedral [Al(OH)4]1- species. At higher pressure and temperature, an additional vibrational mode appears in the spectra at 374 cm-1 (full width at half maximum ~ 20 cm-1). This feature is tentatively attributed to [(OH)3Al-O-Al(OH)3]2- (Moolenaar et al. 1970, Jour. Phys. Chem., 74, 3629-3636). No evidence for KAl(OH)4 was observed, consistent with piston cylinder experiments at 700 oC and 1 GPa (Wohlers & Manning, 2009, Chem. Geol., 262, 310). Upon cooling from high-pressure and high temperature, slow kinetics of corundum regrowth lead to oversaturation in the solutions, as evidenced by sharp peaks at 930 and 1066 cm-1 observed upon cooling. These features are probably due to colloidal aluminum hydroxide. The results provide the first evidence for aluminate polymerization at high pressure and temperature, and offer insights into the causes for enhancement of corundum solubility in alkaline solutions.

Rotational Dynamics of Solutes with Multiple Single Bond Axes Studied by Infrared Pump-Probe Spectroscopy.

PubMed

Okuda, Masaki; Ohta, Kaoru; Tominaga, Keisuke

2018-02-01

To investigate the relationship between the structural degrees of freedom around a vibrational probe and the rotational relaxation process of a solute in solution, we studied the anisotropy decays of three different N 3 -derivatized amino acids in primary alcohol solutions. By performing polarization-controlled IR pump-probe measurements, we reveal that the anisotropy decays of the vibrational probe molecules in 1-alcohol solutions possess two decay components, at subpicosecond and picosecond time scales. On the basis of results showing that the fast relaxation component is insensitive to the vibrational probe molecule, we suggest that the anisotropy decay of the N 3 group on a subpicosecond time scale results from a local, small-amplitude fluctuation of the flexible vibrational probe, which does not depend on the details of its molecular structure. However, the slow relaxation component depends on the solute: with longer alkyl chains attached to the N 3 group, the anisotropy decay of the slow component is faster. Consequently, we conclude that the slow relaxation component corresponds to the reorientational motion of the N 3 group correlated with other intramolecular rotational motions (e.g., rotational motions of the neighboring alkyl chain). Our experimental results provide important insight into understanding the rotational dynamics of solutes with multiple single bond axes in solution.

Vibrational tug-of-war: The pKA dependence of the broad vibrational features of strongly hydrogen-bonded carboxylic acids

NASA Astrophysics Data System (ADS)

Van Hoozen, Brian L.; Petersen, Poul B.

2018-04-01

Medium and strong hydrogen bonds give rise to broad vibrational features frequently spanning several hundred wavenumbers and oftentimes exhibiting unusual substructures. These broad vibrational features can be modeled from first principles, in a reduced dimensional calculation, that adiabatically separates low-frequency modes, which modulate the hydrogen bond length, from high-frequency OH stretch and bend modes that contribute to the vibrational structure. Previously this method was used to investigate the origin of an unusual vibrational feature frequently found in the spectra of dimers between carboxylic acids and nitrogen-containing aromatic bases that spans over 900 cm-1 and contains two broad peaks. It was found that the width of this feature largely originates from low-frequency modes modulating the hydrogen bond length and that the structure results from Fermi resonance interactions. In this report, we examine how these features change with the relative acid and base strength of the components as reflected by their aqueous pKA values. Dimers with large pKA differences are found to have features that can extend to frequencies below 1000 cm-1. The relationships between mean OH/NH frequency, aqueous pKA, and O-N distance are examined in order to obtain a more rigorous understanding of the origin and shape of the vibrational features. The mean OH/NH frequencies are found to correlate well with O-N distances. The lowest OH stretch frequencies are found in dimer geometries with O-N distances between 2.5 and 2.6 Å. At larger O-N distances, the hydrogen bonding interaction is not as strong, resulting in higher OH stretch frequencies. When the O-N distance is smaller than 2.5 Å, the limited space between the O and N determines the OH stretch frequency, which gives rise to frequencies that decrease with O-N distances. These two effects place a lower limit on the OH stretch frequency which is calculated to be near 700 cm-1. Understanding how the vibrational features of strongly hydrogen-bonded structures depend on the relative pKA and other structural parameters will guide studies of biological structures and analysis of proton transfer studies using photoacids.

Supercooling of aqueous dimethylsulfoxide solution at normal and high pressures: Evidence for the coexistence of phase-separated aqueous dimethylsulfoxide solutions of different water structures.

PubMed

Kanno, H; Kajiwara, K; Miyata, K

2010-05-21

Supercooling behavior of aqueous dimethylsulfoxide (DMSO) solution was investigated as a function of DMSO concentration and at high pressures. A linear relationship was observed for T(H) (homogeneous ice nucleation temperature) and T(m) (melting temperature) for the supercooling of aqueous DMSO solution at normal pressure. Analysis of the DTA (differential thermal analysis) traces for homogeneous ice crystallization in the bottom region of the T(H) curve for a DMSO solution of R=20 (R: moles of water/moles of DMSO) at high pressures supported the contention that the second critical point (SCP) of liquid water should exist at P(c2)= approximately 200 MPa and at T(c2)<-100 degrees C (P(c2): pressure of SCP, T(c2): temperature of SCP). The presence of two T(H) peaks for DMSO solutions (R=15, 12, and 10) suggests that phase separation occurs in aqueous DMSO solution (R

Supercooling of aqueous dimethylsulfoxide solution at normal and high pressures: Evidence for the coexistence of phase-separated aqueous dimethylsulfoxide solutions of different water structures

NASA Astrophysics Data System (ADS)

Kanno, H.; Kajiwara, K.; Miyata, K.

2010-05-01

Supercooling behavior of aqueous dimethylsulfoxide (DMSO) solution was investigated as a function of DMSO concentration and at high pressures. A linear relationship was observed for TH (homogeneous ice nucleation temperature) and Tm (melting temperature) for the supercooling of aqueous DMSO solution at normal pressure. Analysis of the DTA (differential thermal analysis) traces for homogeneous ice crystallization in the bottom region of the TH curve for a DMSO solution of R =20 (R: moles of water/moles of DMSO) at high pressures supported the contention that the second critical point (SCP) of liquid water should exist at Pc2=˜200 MPa and at Tc2<-100 °C (Pc2: pressure of SCP, Tc2: temperature of SCP). The presence of two TH peaks for DMSO solutions (R =15, 12, and 10) suggests that phase separation occurs in aqueous DMSO solution (R ≤15) at high pressures and low temperatures (<-90 °C). The pressure dependence of the two TH curves for DMSO solutions of R =10 and 12 indicates that the two phase-separated components in the DMSO solution of R =10 have different liquid water structures [LDL-like and HDL-like structures (LDL: low-density liquid water, HDL: high-density liquid water)] in the pressure range of 120-230 MPa.

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.

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.

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.

Algal polysaccharides as matrices for the immobilization of urease in lipid ultrathin films studied with tensiometry and vibrational spectroscopy: Physical-chemical properties and implications in the enzyme activity.

PubMed

de Brito, Audrey Kalinouski; Nordi, Cristina S F; Caseli, Luciano

2015-11-01

Currently, many biological substances extracted from algae have received special attention because of their intrinsic characteristics, which can be applied to different areas of biotechnology. Therefore, in the current study, exopolysaccharides (EPS) from the microalgae Cryptomonas tetrapirenoidosa were employed as an aqueous subphase of a monolayer formed by the lipid dioctadecyldimethylammonium bromide (DODAB). The primary objective of this approach was to evaluate whether EPS could serve as a matrix for the immobilization of the enzyme urease to produce biosensors for urea. After DODAB was spread on the EPS solutions, urease was injected into the aqueous subphase, and the surface was submitted to compression using lateral barriers. The monolayers were subsequently characterized by surface pressure-area isotherms and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The results indicated that EPS enhanced the adsorption of the enzyme on the lipid monolayer. The mixed films were later transferred to solid supports using the Langmuir-Blodgett (LB) technique and were characterized by transfer ratio, PM-IRRAS, quartz crystal microbalance, and atomic force microscopy. The immobilization of the enzyme on solid supports was fundamental for providing an ideal geometrical accommodation of urease because the interaction of EPS with urease in solution causes a decrease of the relative activity of urease. Therefore, these LB films are promising for the fabrication of future urea biosensors, the architecture of which can be manipulated and enhanced at the molecular level. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Structural, vibrational, DFT and optical studies of a new non-centrosymmetric hybrid material (C4H12N2)[CoBr4

NASA Astrophysics Data System (ADS)

Tllili, Hafsia; Walha, Sandra; Elleuch, Slim; Fares Ali, Basem; Naïli, Houcine

2018-01-01

The crystals of the new organic-inorganic material (C4H12N2)[CoBr4] were grown by slow evaporation technique in aqueous solution and characterized by X-ray diffraction, infrared absorption, Raman spectroscopy scattering and thermal analysis. It crystallizes at room temperature in the non-centrosymmetric space group P212121. The structure is built from isolated [CoBr4]2- anions and piperazinediium (C4H12N2)2+ cations which are connected by a network of Nsbnd H⋯Br hydrogen bonds. Theoretical calculations were performed using density functional theory with the B3LYP/LanL2DZ level for studying the molecular structure and vibrational spectra of the title compound. TDDFT calculations at the same level of theory was undertaken to investigate the electronic properties. Good adhesion is observed between calculated and experimental results. The optical study reveals that the title compound undergoes three optical absorption bands at 641, 666 and 698 nm, respectively with an energy gap estimated to 2.23 eV. Based upon this value and the non-centrosymetric character of the structure, the title compound may show several interesting applications in the field of optoelectronics.

Hydrogen bonded nonlinear optical γ-glycine: Crystal growth and characterization

NASA Astrophysics Data System (ADS)

Narayana Moolya, B.; Jayarama, A.; Sureshkumar, M. R.; Dharmaprakash, S. M.

2005-07-01

Single crystals of γ-glycine(GG) were grown by solvent evaporation technique from a mixture of aqueous solutions of glycine and ammonium nitrate at ambient temperature. X-ray diffraction, thermogravimetric/differential thermal analysis, Fourier transform infrared spectral techniques were employed to characterize the crystal. The lattice parameters were calculated and they agree well with the reported values. GG exists as dipolar ions in which the carboxyl group is present as a carboxylate ion and the amino group as an ammonium ion. Due to this dipolar nature, glycine has a high decomposition temperature. The UV cutoff of GG is below 300 nm and has a wide transparency window, which is suitable for second harmonic generation of laser in the blue region. Nonlinear optical characteristics of GG were studied using Q switched Nd:YAG laser ( λ=1064 nm). The second harmonic generation conversion efficiency of GG is 1.5 times that of potassium dihydrogen phosphate . The X-ray diffraction and Fourier transform infrared spectral studies show the presence of strong hydrogen bonds which create and stabilize the crystal structure in GG. The main contributions to the nonlinear optical properties in GG results from the presence of the hydrogen bond and from the vibrational part due to very intense infrared bands of the hydrogen bond vibrations. GG is thermally stable up to 441 K.

Contaminant Organic Complexes: Their Structure and Energetics in Surface Decontamination Processes

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

Satish C. B. Myneni

2005-12-13

Siderophores are biological macromolecules (400-2000 Da) released by bacteria in iron limiting situations to sequester Fe from iron oxyhydroxides and silicates in the natural environment. These molecules contain hydroxamate and phenolate functional groups, and exhibit very high affinity for Fe{sup 3+}. While several studies were conducted to understand the behavior of siderophores and their application to the metal sequestration and mineral dissolution, only a few of them have examined the molecular structure of siderophores and their interactions with metals and mineral surfaces in aqueous solutions. Improved understanding of the chemical state of different functional moieties in siderophores can assist inmore » the application of these biological molecules in actinide separation, sequestration and decontamination processes. The focus of our research group is to evaluate the (a) functional group chemistry of selected siderophores and their metal complexes in aqueous solutions, and (b) the nature of siderophore interactions at the mineral-water interfaces. We selected desferrioxamine B (desB), a hydroxamate siderophore, and its small structural analogue, acetohydroxamic acid (aHa), for this investigation. We examined the functional group chemistry of these molecules as a function of pH, and their complexation with aqueous and solid phase Fe(III). For solid phase Fe, we synthesized all naturally occurring Fe(III)-oxyhydroxides (goethite, lepidocrocite, akaganeite, feroxyhite) and hematite. We also synthesized Fe-oxides (goethite and hematite) of different sizes to evaluate the influence of particle size on mineral dissolution kinetics. We used a series of molecular techniques to explore the functional group chemistry of these molecules and their complexes. Infrared spectroscopy is used to specifically identify the variations in oxime group as a function of pH and Fe(III) complexation. Resonance Raman spectroscopy was used to evaluate the nature of hydroxamate binding in the case of Fe(III)-siderophore complexes and model ligands. Soft and hard X-ray spectroscopy techniques were used to examine the electronic structure of binding groups, and their local structural environment. The synchrotron X-ray studies were conducted at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (Lawrence Berkeley National Laboratory). These experimental vibrational and X-ray spectroscopy studies were complemented with density functional theory calculations. The highlight of this study is the evaluation of the fundamental electronic state information of the hydroxamate moiety in siderophores during deprotonation and Fe(III) complexation. The applications of soft X-ray studies are also new, and were applied, for the first time, to examine the chemistry of organic macromolecules in aqueous solutions.« less

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.

Stability of GO Modified by Different Dispersants in Cement Paste and Its Related Mechanism.

PubMed

Long, Wu-Jian; Fang, Changle; Wei, Jingjie; Li, Haodao

2018-05-18

Graphene oxide (GO) is a potential material to be used as a nano-reinforcement in cement matrix. However, a prerequisite for GO to fulfill its function in the cement matrix is homogeneous dispersion. In this study, the effects of three different dispersing agents (DAs), including polycarboxylate-based high range water reducer (P-HRWR), naphthalene-based high range water reducer (N-HRWR), and air entraining agent (AEA) on the dispersion of GO in aqueous solution, simulated concrete pore solution (SCPS), and suspension of cement pastes were sequentially investigated. Results showed that the dispersion effect of GO in aqueous solutions was improved with different DAs. However, the homogeneous dispersion of GO in aqueous solution re-agglomerated in SCPS and suspension of cement pastes. It was concluded that as the cement content and pH of aqueous solutions increased, GOs re-agglomerated and precipitated in an alkaline solution. A possible mechanism was proposed in this study and it was believed that electrostatic interactions and steric hindrance provided by the P-HRWR further made GOs stable in aqueous solutions. The ions and pH of cement pastes increased with the increasing amount of cement, which caused the separation of P-HRWR from GOs. Therefore, GOs were re-agglomerated and absorbed on the surface of the cement particles, resulting in GOs sedimentation.

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.

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.

Preparation of Chitosan Coated Magnetic Hydroxyapatite Nanoparticles and Application for Adsorption of Reactive Blue 19 and Ni2+ Ions

PubMed Central

Nguyen, Van Cuong; Pho, Quoc Hue

2014-01-01

An adsorbent called chitosan coated magnetic hydroxyapatite nanoparticles (CS-MHAP) was prepared with the purpose of improvement for the removal of Ni2+ ions and textile dye by coprecipitation. Structure and properties of CS-MHAP were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). Weight percent of chitosan was investigated by thermal gravimetric analysis (TGA). The prepared CS-MHAP presents a significant improvement on the removal efficiency of Ni2+ ions and reactive blue 19 dye (RB19) in comparison with chitosan and magnetic hydroxyapatite nanoparticles. Moreover, the adsorption capacities were affected by several parameters such as contact time, initial concentration, adsorbent dosage, and initial pH. Interestingly, the prepared adsorbent could be easily recycled from an aqueous solution by an external magnet and reused for adsorption with high removal efficiency. PMID:24592158

Conversion of post consumer waste polystyrene into a high value adsorbent and its sorptive properties for Congo Red removal from aqueous solution.

PubMed

Chaukura, Nhamo; Mamba, Bhekie B; Mishra, Shivani B

2017-05-15

Using post-consumer waste polystyrene (WPS), a conjugated microporous polymer (CMP) was synthesised and activated into a sulphonic-group carrying resin (SCMP). The surface chemistry of the materials showed a decline in both the aromatic CH and aliphatic CH 2 stretching vibrations confirming successful crosslinking. The synthesised polymers were thermally stable with decomposition temperatures above 300 °C, had surface heterogeneity, and BET surface areas of 752 and 510 m 2 /g, respectively. A distribution of pores ranging from meso- to micro-pores was comparable to other CMPs. The materials had maximum adsorption capacities of 500 and 357 mg/g for Congo Red (CR) on CMP and SCMP, respectively. Converting waste polystyrene to an adsorbent is a cost effective way of handling waste and simultaneously providing material for wastewater remediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of calcination temperature on the formation and magnetic properties of ZnMn2O4 spinel

NASA Astrophysics Data System (ADS)

Hermanto, B.; Ciswandi; Afriani, F.; Aryanto, D.; Sudiro, T.

2018-03-01

The spinel based on transition-metal oxides has a typical composition of AB2O4. In this study, the ZnMn2O4 spinel was synthesized using a powder metallurgy technique. The Zn and Mn metallic powders with an atomic ratio of 1:2 were mechanically alloyed for 3 hours in aqueous solution. The mixed powder was then calcined in a muffle furnace at elevated temperature of 400, 500 and 600 °C. The X-ray Diffractometer (XRD) was used to evaluate the formation of a ZnMn2O4 spinel structure. The magnetic properties of the sample at varying calcination temperatures were characterized by a Vibrating Sample Magnetometer (VSM). The results show that the fraction of ZnMn2O4 spinel formation increases with the increase of calcination temperature. The calcination temperature also affects the magnetic properties of the samples.

Crystal growth, thermal and optical studies of semiorganic nonlinear optical material: L-lysine hydrochloride dihydrate

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

Kalaiselvi, D.; Mohan Kumar, R.; Jayavel, R.

2008-07-01

Single crystals of L-lysine hydrochloride dihydrate (LLHCD), a nonlinear optical material, have been grown by slow cooling technique from its aqueous solution. LLHCD was found to be highly soluble in water. The grown crystals have been subjected to single crystal X-ray diffraction to confirm the structure and to estimate the lattice parameters. The vibrational structure of the molecule is elucidated from FTIR spectra. Thermal analysis revealed the thermal stability of the grown crystals. The optical transmittance spectrum shows that the material possesses good optical transparency in the entire visible region with a UV cut-off wavelength at 228 nm. The mechanicalmore » properties of the grown crystal have been studied using Vicker's microhardness test. The laser damage threshold of 52.25 MW/cm{sup 2} has been measured by irradiating Q-switched Nd:YAG laser (1064 nm)« less

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.

Spectroscopic studies on the conformational transitions of a bovine growth hormone releasing factor analog

NASA Astrophysics Data System (ADS)

Sarver, Ronald W.; Friedman, Alan R.; Thamann, Thomas J.

1997-10-01

The secondary structure of the bovine growth hormone releasing factor analog, [Ile 2, Ser 8,28, Ala 15, Leu 27, Hse 30] bGRF(1-30)-NH-Ethyl, acetate salt (U-90699F) was studied in solution by Fourier transform infrared and Raman spectroscopies. Spectroscopic studies revealed that concentrated aqueous solutions of U-90699F (100 mg ml -1) undergo a secondary structure transition from disordered coil/α-helix to intermolecular β-sheet. Disordered coil and α-helical structure were grouped together in the infrared and Raman studies since the amide I vibrations are close in frequency and overlap in assignments was possible. Before the conformational transition, the facile exchange of the peptide's amide hydrogens for deuterium indicated that the majority of amide hydrogens were readily accessible to solvent. The kinetics of the conformational transition coincided with an increase in solution viscosity and turbidity. An initiation phase preceded the conformational transition during which only minor spectral changes were observed by infrared spectroscopy. The initiation phase and reaction kinetics were consistent with a highly cooperative nucleation ultimately leading to a network of intermolecular β-sheet structure and gel formation. Increased temperature accelerated the conformational transition. The conformational transition was thermally irreversible but the β-sheet structure of aggregated or gelled peptide could be disrupted by dilution and agitation.

Magnetic α-Fe2O3/MCM-41 nanocomposites: preparation, characterization, and catalytic activity for methylene blue degradation.

PubMed

Ursachi, Irina; Stancu, Alexandru; Vasile, Aurelia

2012-07-01

Catalysts based on nanosized magnetic iron oxide stabilized inside the pore system of ordered mesoporous silica MCM-41 have been prepared. The obtained materials were characterized by powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and N(2) adsorption-desorption isotherm. XRD analysis showed that the obtained materials consist from the pure hematite crystalline phase (α-Fe(2)O(3)) dispersed within ordered mesoporous silica MCM-41. Magnetic measurements show that the obtained nanocomposites exhibit at room temperature weak ferromagnetic behavior with slender hysteresis. The catalytic activity of the magnetic α-Fe(2)O(3)/MCM-41 nanocomposites was evaluated by the degradation of methylene blue (MB) aqueous solution. For this purpose, an ultrasound-assisted Fenton-like process was used. The effect of solution pH on degradation of MB was investigated. The results indicated that US-H(2)O(2)-α-Fe(2)O(3)/MCM-41 nanocomposite system is effective for the degradation of MB, suggesting its great potential in removal of dyes from wastewater. It was found that the degradation rate of MB increases with decrease in the pH value of the solution. Copyright © 2012 Elsevier Inc. All rights reserved.

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.

Benchmark solution for vibrations from a moving point source in a tunnel embedded in a half-space

NASA Astrophysics Data System (ADS)

Yuan, Zonghao; Boström, Anders; Cai, Yuanqiang

2017-01-01

A closed-form semi-analytical solution for the vibrations due to a moving point load in a tunnel embedded in a half-space is given in this paper. The tunnel is modelled as an elastic hollow cylinder and the ground surrounding the tunnel as a linear viscoelastic material. The total wave field in the half-space with a cylindrical hole is represented by outgoing cylindrical waves and down-going plane waves. To apply the boundary conditions on the ground surface and at the tunnel-soil interface, the transformation properties between the plane and cylindrical wave functions are employed. The proposed solution can predict the ground vibration from an underground railway tunnel of circular cross-section with a reasonable computational effort and can serve as a benchmark solution for other computational methods. Numerical results for the ground vibrations on the free surface due to a moving constant load and a moving harmonic load applied at the tunnel invert are presented for different load velocities and excitation frequencies. It is found that Rayleigh waves play an important role in the ground vibrations from a shallow tunnel.

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.

Dynamic cues for whisker-based object localization: An analytical solution to vibration during active whisker touch

PubMed Central

Vaxenburg, Roman; Wyche, Isis; Svoboda, Karel; Efros, Alexander L.

2018-01-01

Vibrations are important cues for tactile perception across species. Whisker-based sensation in mice is a powerful model system for investigating mechanisms of tactile perception. However, the role vibration plays in whisker-based sensation remains unsettled, in part due to difficulties in modeling the vibration of whiskers. Here, we develop an analytical approach to calculate the vibrations of whiskers striking objects. We use this approach to quantify vibration forces during active whisker touch at a range of locations along the whisker. The frequency and amplitude of vibrations evoked by contact are strongly dependent on the position of contact along the whisker. The magnitude of vibrational shear force and bending moment is comparable to quasi-static forces. The fundamental vibration frequencies are in a detectable range for mechanoreceptor properties and below the maximum spike rates of primary sensory afferents. These results suggest two dynamic cues exist that rodents can use for object localization: vibration frequency and comparison of vibrational to quasi-static force magnitude. These complement the use of quasi-static force angle as a distance cue, particularly for touches close to the follicle, where whiskers are stiff and force angles hardly change during touch. Our approach also provides a general solution to calculation of whisker vibrations in other sensing tasks. PMID:29584719

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.

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...

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.

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.

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

An approach to determination of shunt circuits parameters for damping vibrations

NASA Astrophysics Data System (ADS)

Matveenko; Iurlova; Oshmarin; Sevodina; Iurlov

2018-04-01

This paper considers the problem of natural vibrations of a deformable structure containing elements made of piezomaterials. The piezoelectric elements are connected through electrodes to an external electric circuit, which consists of resistive, inductive and capacitive elements. Based on the solution of this problem, the parameters of external electric circuits are searched for to allow optimal passive control of the structural vibrations. The solution to the problem is complex natural vibration frequencies, the real part of which corresponds to the circular eigenfrequency of vibrations and the imaginary part corresponds to its damping rate (damping ratio). The analysis of behaviour of the imaginary parts of complex eigenfrequencies in the space of external circuit parameters allows one to damp given modes of structure vibrations. The effectiveness of the proposed approach is demonstrated using a cantilever-clamped plate and a shell structure in the form of a semi-cylinder connected to series resonant ? circuits.

[Mechanism of gold solid extraction from aurocyanide solution using D3520 resin impregnated with TRPO].

PubMed

Yang, Xiang-Jun; Wang, Shi-Xiong; Zou, An-Qin; Chen, Jing; Guo, Hong

2014-02-01

Trialkyphosphine oxides (TRPO) was successfully used for the impregnation of D3520 resin to prepare an extractant-impregnated resin (EIR). Solid extraction of Au(I) from alkaline cyanide solution was studied using this extractant-impregnated resin (EIR), with addition of cetyltrimethylammonium bromide (CTMAB), directly into the aurous aqueous phase in advance. The mechanism of solid extraction was further investigated by means of FTIR, XPS and SEM. The column separation studies have shown that cationic surfactant CTMAB played a key role in the solid phase extraction, and the resin containing TRPO were effective for the extraction of gold when the molar ratio of CTMAB: Au( I ) reached 1:1. FTIR spectroscopy of gold loaded EIR showed that the frequency of C[triple bond]N stretching vibration was at 2144 cm(-1), and the frequency of P=O stretching vibration shifted to lower frequency from 1153 to 1150 cm(-1). The XPS spectrum of N(1s), Au(4f7/2) and Au(4f5/2) sugges- ted that the coordination environment of gold did not change before and after extraction, and gold was still as the form of Au (CN)2(-) anion exiting in the loaded resin; O(1s) spectrum showed that the chemically combined water significantly increased after solid extraction from 30.74% to 42.34%; Comparing to the P(2p) spectrum before and after extraction, the binding energy increased from 132. 15 to 132. 45 eV, indicating there maybe existing hydrogen-bond interaction between P=O and water molecule, such as P=O...H-O-H. The above results obtained established that in the solid extraction process, the hydrophobic ion association [CTMA+ x Au(CN)] diffused from the bulk solution into the pores of the EIR, and then be solvated by TRPO adsorbed in the pores through hydrogen bonding bridged by the water molecules.

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.

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.

Dynamic characteristics of a vibrating beam with periodic variation in bending stiffness

NASA Technical Reports Server (NTRS)

Townsend, John S.

1987-01-01

A detailed dynamic analysis is performed of a vibrating beam with bending stiffness periodic in the spatial coordinate. Using a perturbation expansion technique the free vibration solution is obtained in a closed-form, and the effects of system parameters on beam response are explored. It is found that periodic stiffness acts to modulate the modal displacements from the characteristic shape of a simple sine wave. The results are verified by a finite element solution and through experimental testing.

The vibrational spectra and structures of dimethyl oxaloacetate and dimethyl oxaloacetate- d2

NASA Astrophysics Data System (ADS)

Schiering, David W.; Katon, J. E.

The complete vibrational spectra of dimethyl oxaloacetate and dimethyl oxaloacetate- d2 have been recorded and analyzed. The i.r. spectra were recorded at liquid N 2 as well as ambient temperature. Tentative vibrational assignments are proposed based on an enol structure in the crystalline phase. In solution, dimethyl oxaloacetate exists as a tautomeric mixture of keto and enol forms. Evidence for the existence of different enol conformers in CCl 4 and CS 2 solutions is also presented.

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

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

Unravelling the mechanisms of vibrational relaxation in solution.

PubMed

Grubb, Michael P; Coulter, Philip M; Marroux, Hugo J B; Orr-Ewing, Andrew J; Ashfold, Michael N R

2017-04-01

We present a systematic study of the mode-specific vibrational relaxation of NO 2 in six weakly-interacting solvents (perfluorohexane, perfluoromethylcyclohexane, perfluorodecalin, carbon tetrachloride, chloroform, and d-chloroform), chosen to elucidate the dominant energy transfer mechanisms in the solution phase. Broadband transient vibrational absorption spectroscopy has allowed us to extract quantum state-resolved relaxation dynamics of the two distinct NO 2 fragments produced from the 340 nm photolysis of N 2 O 4 → NO 2 (X) + NO 2 (A) and their separate paths to thermal equilibrium. Distinct relaxation pathways are observed for the NO 2 bending and stretching modes, even at energies as high as 7000 cm -1 above the potential minimum. Vibrational energy transfer is governed by different interaction mechanisms in the various solvent environments, and proceeds with timescales ranging from 20-1100 ps. NO 2 relaxation rates in the perfluorocarbon solvents are identical despite differences in acceptor mode state densities, infrared absorption cross sections, and local solvent structure. Vibrational energy is shown to be transferred to non-vibrational solvent degrees of freedom (V-T) through impulsive collisions with the perfluorocarbon molecules. Conversely, NO 2 relaxation in chlorinated solvents is reliant on vibrational resonances (V-V) while V-T energy transfer is inefficient and thermal excitation of the surrounding solvent molecules inhibits faster vibrational relaxation through direct complexation. Intramolecular vibrational redistribution allows the symmetric stretch of NO 2 to act as a gateway for antisymmetric stretch energy to exit the molecule. This study establishes an unprecedented level of detail for the cooling dynamics of a solvated small molecule, and provides a benchmark system for future theoretical studies of vibrational relaxation processes in solution.

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.

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.

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.

A Raman and UV-Vis study of catecholamines oxidized with Mn(III)

NASA Astrophysics Data System (ADS)

Barreto, W. J.; Ponzoni, S.; Sassi, P.

1998-12-01

A UV-Vis and Raman spectroscopy study of three aminochromes generated through Mn 3+ oxidation of the dopamine, L-dopa and adrenaline molecules at physiological pH was performed. The UV-Vis spectra of the catecholamines oxidized using Mn 3+ in buffer solution at pH 7.2 show a band at ca. 300 nm, formed by two transitions at 280 nm and 300 nm assigned to an La and Lb transition respectively, and other at ca. 470 nm assigned to an n- π* transition localized in the carbonyl group. This assignment is suggested by the UV-Vis and Raman spectra of ortho-aminoquinone generated by MnO 2 oxidation of a dopamine aqueous acidic solution. The resonance Raman spectra of the three chromes at buffer pH 7.2 show a very similar feature and the most intense bands are observed in the spectral range 1100-1800 cm -1. The band around 1680 cm -1 for the three compounds is assigned to a ν(CO) stretching vibration, 1630 cm -1 to the ν(CC) ring mode, two bands at 1423, 1439 cm -1; 1427, 1438 cm -1 and 1456, 1475 cm -1 are assigned to a ν(CN +) vibration, for aminochrome, dopachrome and adrenochrome, respectively. The excitation profiles for the most intense bands for aminochrome and adrenochrome were obtained. The band assigned to the ν(CN +) present a red shift with respect to the visible band peak, however the band in adrenochrome at 1475 cm -1 shows a profile similar to ν(CO) and ν(CC) modes that reflects the methyl group effect on mixing this mode more effectively with the ν(CC) ring mode.

Nucleation-dependant chemical bonding paradigm: the effect of rare earth ions on the nucleation of urea in aqueous solution.

PubMed

Chen, Xiaoyan; Sun, Congting; Wu, Sixin; Xue, Dongfeng

2017-03-29

Rare earth ions can be used to construct a variety of novel structures and are favorable to chemical bonding regulation and design. In this study, the chemical bonding paradigm between rare earth ions (Ln 3+ ) and urea molecules in an aqueous solution can be tracked by the evolution of C[double bond, length as m-dash]O, NH 2 , and CN vibration bands during the urea nucleation stage. Rare earth ions such as La 3+ , Gd 3+ , and Lu 3+ can manipulate the nucleation time of urea via regulating the nucleation-dependant N-C[double bond, length as m-dash]OH-N hydrogen-bonding between urea molecules. Two types of chemical bondings between Ln 3+ and urea molecules have been confirmed, which are Ln 3+ O[double bond, length as m-dash]C-N and Ln 3+ NH 2 -C. Compared with Ln 3+ NH 2 -C, Ln 3+ prefers to coordinate with the O[double bond, length as m-dash]C bond in urea. With a higher concentration of rare earth ions in the solution, some N-C[double bond, length as m-dash]OH-N hydrogen bonds are broken as a consequence of the incorporation of Ln 3+ into the lattice, resulting in the decreased symmetry of local urea molecules in the crystalline nuclei and the consequent Ln 3+ concentration-dependent nucleation time of urea. Moreover, using the ionic electronegativity scale of Ln 3+ , the different effects of La 3+ , Gd 3+ , and Lu 3+ on urea nucleation can be further distinguished. The present study provides basic data for unrevealing the chemical bonding regulation role of rare earth ions in the formation of hydrogen bonded materials, which may give insight into the design and fabrication of novel materials utilizing rare earth ions to adjust the chemical bonding process.

Site percolation and Vogel-Fulcher behavior on picosecond time scales in concentrated electrolytes: Raman spectra of aqueous solutions of LiSCN and KSCN

NASA Astrophysics Data System (ADS)

Rothschild, Walter G.; Perrot, Michel

1988-11-01

In this paper we further explore the applicability of a vibrational T2 process based on the extended-exponential modulation model [Rothschild, Perrot, and Guillaume, J. Chem. Phys. 87, 7293 (1987)] to Raman correlation data of concentrated aqueous solutions of LiSCN and KSCN [Katō, Mol. Phys. 48, 1119 (1983); Katō and Takenaka, Mol. Phys. 46, 257 (1982)]. In general, the values of dispersion parameter α in the modulation function exp[-(t/τ)α], obtained from the fit of the theory to the isotropic correlation data of the CN oscillator, predict the prevalence of interrelated, collective dynamic processes in the medium that are the cause of the instantaneous oscillator transition frequency shifts (motional narrowing). In particular we predict, from the observed concentration dependence of α, strong short-time (fraction to several ps) cation-water-anion interactions that, in the more concentrated LiSCN-H2O systems at 303 K, are above a site percolation threshold with a value of α˜0.3 (close to that found in glasses). The expectation value of t, =τΓ(1+1/α), becomes critical near a concentration of 5 mol/l and shows a pronounced Vogel-Fulcher-type temperature dependence (T0=250 K) in the 10 mol/l LiSCN-H2O system over a range 0.45-76 ps. However, since α approaches its limiting value=1 at the highest temperature reported (353 K), the large-cluster cation-water-anion distributions in LiSCN-H2O must be rather tenuous. In contrast, the characteristics of α and of for the KSCN-H2O systems agree with the relatively weak cation-water forces; the (inverse) concentration dependence of α is linear, its temperature dependence is flat, and the Vogel-Fulcher-type temperature behavior of for the 10 mol/l solution stretches merely from 0.7 to 1.4 ps.

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.

Stimulated low-frequency Raman scattering in aqueous suspension of nanoparticles

NASA Astrophysics Data System (ADS)

Averyushkin, Anatolii S.; Baranov, Anatoly N.; Bulychev, Nikolay A.; Kazaryan, Mishik A.; Kudryavtseva, Anna D.; Shevchenko, Mikhail A.; Strokov, Maxim A.; Tcherniega, Nikolay V.; Zemskov, Konstantin I.

2018-04-01

The low-frequency acoustic mode in nanoparticles of different nature in aqueous suspension has been studied by stimulated low-frequency Raman scattering (SLFRS). Nanoparticles investigated (CuO, Ag, Au, ZnS) had different dimensions and different vibrational properties. Synthesis of cupric oxide nanoparticles in acoustoplasma discharge is described in details. SLFRS has been excited by nanosecond pulses of ruby laser. Spectra of the scattered light had been registered with the help of Fabry-Perot interferometer. SLFRS conversion efficiency, threshold and frequency shift of the scattered light are measured.

Spectroscopy and picosecond dynamics of aqueous NO2

NASA Astrophysics Data System (ADS)

Gadegaard, Ane Riis; Thøgersen, Jan; Jensen, Svend Knak; Nielsen, Jakob Brun; Jena, Naresh K.; Odelius, Michael; Jensen, Frank; Keiding, Søren Rud

2014-08-01

We investigate the formation of aqueous nitrogen dioxide, NO2 formed through femtosecond photolysis of nitrate, NO_3^ - ( {aq} ) and nitromethane CH3NO2(aq). Common to the experiments is the observation of a strong induced absorption at 1610 ± 10 cm-1, assigned to the asymmetric stretch vibration in the ground state of NO2. This assignment is substantiated through isotope experiments substituting 14N by 15N, experiments at different pH values, and by theoretical calculations and simulations of NO2-D2O clusters.

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.

Vibrational tug-of-war: The pKA dependence of the broad vibrational features of strongly hydrogen-bonded carboxylic acids.

PubMed

Van Hoozen, Brian L; Petersen, Poul B

2018-04-07

Medium and strong hydrogen bonds give rise to broad vibrational features frequently spanning several hundred wavenumbers and oftentimes exhibiting unusual substructures. These broad vibrational features can be modeled from first principles, in a reduced dimensional calculation, that adiabatically separates low-frequency modes, which modulate the hydrogen bond length, from high-frequency OH stretch and bend modes that contribute to the vibrational structure. Previously this method was used to investigate the origin of an unusual vibrational feature frequently found in the spectra of dimers between carboxylic acids and nitrogen-containing aromatic bases that spans over 900 cm -1 and contains two broad peaks. It was found that the width of this feature largely originates from low-frequency modes modulating the hydrogen bond length and that the structure results from Fermi resonance interactions. In this report, we examine how these features change with the relative acid and base strength of the components as reflected by their aqueous pK A values. Dimers with large pK A differences are found to have features that can extend to frequencies below 1000 cm -1 . The relationships between mean OH/NH frequency, aqueous pK A , and O-N distance are examined in order to obtain a more rigorous understanding of the origin and shape of the vibrational features. The mean OH/NH frequencies are found to correlate well with O-N distances. The lowest OH stretch frequencies are found in dimer geometries with O-N distances between 2.5 and 2.6 Å. At larger O-N distances, the hydrogen bonding interaction is not as strong, resulting in higher OH stretch frequencies. When the O-N distance is smaller than 2.5 Å, the limited space between the O and N determines the OH stretch frequency, which gives rise to frequencies that decrease with O-N distances. These two effects place a lower limit on the OH stretch frequency which is calculated to be near 700 cm -1 . Understanding how the vibrational features of strongly hydrogen-bonded structures depend on the relative pK A and other structural parameters will guide studies of biological structures and analysis of proton transfer studies using photoacids.

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.

Molecular dynamics simulation studies of the interactions between ionic liquids and amino acids in aqueous solution.

PubMed

Tomé, Luciana I N; Jorge, Miguel; Gomes, José R B; Coutinho, João A P

2012-02-16

Although the understanding of the influence of ionic liquids (ILs) on the solubility behavior of biomolecules in aqueous solutions is relevant for the design and optimization of novel biotechnological processes, the underlying molecular-level mechanisms are not yet consensual or clearly elucidated. In order to contribute to the understanding of the molecular interactions established between amino acids and ILs in aqueous media, classical molecular dynamics (MD) simulations were performed for aqueous solutions of five amino acids with different structural characteristics (glycine, alanine, valine, isoleucine, and glutamic acid) in the presence of 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imide. The results from MD simulations enable to relate the properties of the amino acids, namely their hydrophobicity, to the type and strength of their interactions with ILs in aqueous solutions and provide an explanation for the direction and magnitude of the solubility phenomena observed in [IL + amino acid + water] systems by a mechanism governed by a balance between competitive interactions of the IL cation, IL anion, and water with the amino acids.

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

DOEpatents

Fries, B.A.

1959-11-10

A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

Sorption of tetracycline antibiotics on hyper-crosslinked polystyrene from aqueous and aqueous-organic media

NASA Astrophysics Data System (ADS)

Udalova, A. Yu.; Dmitrienko, S. G.; Apyari, V. V.

2015-06-01

The sorption of tetracycline, oxytetracycline, chlortetracycline, and doxycycline on hyper-cross-linked polystyrene from aqueous and aqueous-organic solutions is studied under static and dynamic conditions in order to extend the range of the sorbents suitable for sorption isolation and the preconcentration of tetracycline antibiotics. Features of tetracycline sorption depending on the acidity of a solution and the nature and concentration of the compounds are explained. It is shown that hyper-crosslinked polystyrene can be used for the group sorption preconcentration of these compounds.

Hydrothermal Synthesis and Photocatalytic Property of β-Ga2O3 Nanorods

NASA Astrophysics Data System (ADS)

Reddy, L. Sivananda; Ko, Yeong Hwan; Yu, Jae Su

2015-09-01

Gallium oxide (Ga2O3) nanorods were facilely prepared by a simple hydrothermal synthesis, and their morphology and photocatalytic property were studied. The gallium oxide hydroxide (GaOOH) nanorods were formed in aqueous growth solution containing gallium nitrate and ammonium hydroxide at 95 °C of growth temperature. Through the calcination treatment at 500 and 1000 °C for 3 h, the GaOOH nanorods were converted into single crystalline α-Ga2O3 and β-Ga2O3 phases. From X-ray diffraction analysis, it could be confirmed that a high crystalline quality of β-Ga2O3 nanorods was achieved by calcinating at 1000 °C. The thermal behavior of the Ga2O3 nanorods was also investigated by differential thermal analysis, and their vibrational bands were identified by Fourier transform infrared spectroscopy. In order to examine the photocatalytic activity of samples, the photodegradation of Rhodamine B solution was observed under UV light irradiation. As a result, the α-Ga2O3 and β-Ga2O3 nanorods exhibited high photodegeneration efficiencies of 62 and 79 %, respectively, for 180 min of UV irradiation time.

Crystal growth, structural, optical, spectral and thermal studies of tris(L-phenylalanine)L-phenylalaninium nitrate: a new organic nonlinear optical material.

PubMed

Prakash, M; Geetha, D; Lydia Caroline, M

2011-10-15

Tris(L-phenylalanine)L-phenylalaninium nitrate, C(9)H(12)NO(2)(+)·NO(3)(-)·3C(9)H(11)NO(2) (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG. Copyright © 2011 Elsevier B.V. All rights reserved.

Hydrothermal Synthesis and Photocatalytic Property of β-Ga2O3 Nanorods.

PubMed

Reddy, L Sivananda; Ko, Yeong Hwan; Yu, Jae Su

2015-12-01

Gallium oxide (Ga2O3) nanorods were facilely prepared by a simple hydrothermal synthesis, and their morphology and photocatalytic property were studied. The gallium oxide hydroxide (GaOOH) nanorods were formed in aqueous growth solution containing gallium nitrate and ammonium hydroxide at 95 °C of growth temperature. Through the calcination treatment at 500 and 1000 °C for 3 h, the GaOOH nanorods were converted into single crystalline α-Ga2O3 and β-Ga2O3 phases. From X-ray diffraction analysis, it could be confirmed that a high crystalline quality of β-Ga2O3 nanorods was achieved by calcinating at 1000 °C. The thermal behavior of the Ga2O3 nanorods was also investigated by differential thermal analysis, and their vibrational bands were identified by Fourier transform infrared spectroscopy. In order to examine the photocatalytic activity of samples, the photodegradation of Rhodamine B solution was observed under UV light irradiation. As a result, the α-Ga2O3 and β-Ga2O3 nanorods exhibited high photodegeneration efficiencies of 62 and 79 %, respectively, for 180 min of UV irradiation time.

Ionization state of L-phenylalanine at the air-water interface.

PubMed

Griffith, Elizabeth C; Vaida, Veronica

2013-01-16

The ionization state of organic molecules at the air-water interface and the related problem of the surface pH of water have significant consequences on the catalytic role of the surface in chemical reactions and are currently areas of intense research and controversy. In this work, infrared reflection-absorption spectroscopy (IRRAS) is used to identify changes in the ionization state of L-phenylalanine in the surface region versus the bulk aqueous solution. L-phenylalanine has the unique advantage of possessing two different hydrophilic groups, a carboxylic acid and an amine base, which can deprotonate and protonate respectively depending on the ionic environment they experience at the water surface. In this work, the polar group vibrations in the surface region are identified spectroscopically in varying bulk pH solutions, and are subsequently compared with the ionization state of the polar groups of molecules residing in the bulk environment. The polar groups of L-phenylalanine at the surface transition to their deprotonated state at bulk pH values lower than the molecules residing in the bulk, indicating a decrease in their pK(a) at the surface, and implying an enhanced hydroxide ion concentration in the surface region relative to the bulk.

NEPTUNIUM SOLVENT EXTRACTION PROCESS

DOEpatents

Dawson, L.R.; Fields, P.R.

1959-10-01

The separation of neptunium from an aqueous solution by solvent extraction and the extraction of neptunium from the solvent solution are described. Neptunium is separated from an aqueous solution containing tetravalent or hexavalent neptunium nitrate, nitric acid, and a nitrate salting out agent, such as sodium nitrate, by contacting the solution with an organic solvent such as diethyl ether. Subsequently, the neptunium nitrate is extracted from the organic solvent extract phase with water.

The effect of deep eutectic solvents on catalytic function and structure of bovine liver catalase.

PubMed

Harifi-Mood, Ali Reza; Ghobadi, Roohollah; Divsalar, Adeleh

2017-02-01

Aqueous solutions of reline and glyceline, the most common deep eutectic solvents, were used as a medium for Catalase reaction. By some spectroscopic methods such as UV-vis, fluorescence and circular dichroism (CD) function and structure of Catalase were investigated in aqueous solutions of reline and glyceline. These studies showed that the binding affinity of the substrate to the enzyme increased in the presence of 100mM glyceline solution, which contrasts with reline solution that probably relates to instructive changes in secondary structure of protein. Meanwhile, enzyme remained nearly 70% and 80% active in this concentration of glyceline and reline solutions respectively. In the high concentration of DES solutions, enzyme became mainly inactive but surprisingly stayed in nearly 40% active in choline chloride solution, which is the common ion species in reline and glyceline solvents. It is proposed that the chaotropic nature of choline cation might stop the reducing trend of activity in concentrated choline chloride solutions but this instructive effect is lost in aqueous deep eutectic solvents. In this regard, the presence of various concentrations of deep eutectic solvents in the aqueous media of human cells would be an activity adjuster for this important enzyme in its different operation conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydration and dielectrical properties of aqueous pyrrolidinium trifluoroacetate solutions

NASA Astrophysics Data System (ADS)

Lyashchenko, A. K.; Balakaeva, I. V.; Simonova, Yu. A.; Timofeeva, L. M.

2017-10-01

Results from microwave measurements of the dielectrical properties of aqueous pyrrolidinium trifluoroacetate solutions at maximum water dispersion frequencies (13-25 GHz) and temperatures of 288, 298, and 308 K are given. The static dielectrical constants, times, and activation parameters of the dielectrical relaxation of solutions are calculated. The enthalpy and time of dielectrical relaxation activation are increased by deceleration of the motion of water molecules in the hydrate shells of ions. The changes in dielectrical parameters are in this case minimal in a series of aqueous solutions of diallylammonium salts with cations of different structures and degrees of substitution. It is shown that pyrrolidinium ions are characterized by weak hydrophobic hydration.

Marangoni Flow Induced Evaporation Enhancement on Binary Sessile Drops.

PubMed

Chen, Pin; Harmand, Souad; Ouenzerfi, Safouene; Schiffler, Jesse

2017-06-15

The evaporation processes of pure water, pure 1-butanol, and 5% 1-butanol aqueous solution drops on heated hydrophobic substrates are investigated to determine the effect of temperature on the drop evaporation behavior. The evolution of the parameters (contact angle, diameter, and volume) during evaporation measured using a drop shape analyzer and the infrared thermal mapping of the drop surface recorded by an infrared camera were used in investigating the evaporation process. The pure 1-butanol drop does not show any thermal instability at different substrate temperatures, while the convection cells created by the thermal Marangoni effect appear on the surface of the pure water drop from 50 °C. Because 1-butanol and water have different surface tensions, the infrared video of the 5% 1-butanol aqueous solution drop shows that the convection cells are generated by the solutal Marangoni effect at any substrate temperature. Furthermore, when the substrate temperature exceeds 50 °C, coexistence of the thermal and solutal Marangoni flows is observed. By analyzing the relation between the ratio of the evaporation rate of pure water and 1-butanol aqueous solution drops and the Marangoni number, a series of empirical equations for predicting the evaporation rates of pure water and 1-butanol aqueous solution drops at the initial time as well as the equations for the evaporation rate of 1-butanol aqueous solution drop before the depletion of alcohol are derived. The results of these equations correspond fairly well to the experimental data.

METHOD OF SEPARATING PLUTONIUM

DOEpatents

Heal, H.G.

1960-02-16

BS>A method of separating plutonium from aqueous nitrate solutions of plutonium, uranium. and high beta activity fission products is given. The pH of the aqueous solution is adjusted between 3.0 to 6.0 with ammonium acetate, ferric nitrate is added, and the solution is heated to 80 to 100 deg C to selectively form a basic ferric plutonium-carrying precipitate.

Cesium recovery from aqueous solutions

DOEpatents

Goodhall, C. A.

1960-09-13

A process for recovering cesium from aqueous solutions is given in which precipitation on zinc ferricyanide is used. The precipitation is preferably carried out in solutions containing at least 0.0004M zinc ferricyanide, an acidity ranging from 0.2N mineral acid to 0.61N acid deficiency, and 1 to 2.5M aluminum nitrate. (D.L.C.)

Proton transfer reactions and dynamics in CH(3)OH-H(3)O(+)-H(2)O complexes.

PubMed

Sagarik, Kritsana; Chaiwongwattana, Sermsiri; Vchirawongkwin, Viwat; Prueksaaroon, Supakit

2010-01-28

Proton transfer reactions and dynamics in hydrated complexes formed from CH(3)OH, H(3)O(+) and H(2)O were studied using theoretical methods. The investigations began with searching for equilibrium structures at low hydration levels using the DFT method, from which active H-bonds in the gas phase and continuum aqueous solution were characterized and analyzed. Based on the asymmetric stretching coordinates (Deltad(DA)), four H-bond complexes were identified as potential transition states, in which the most active unit is represented by an excess proton nearly equally shared between CH(3)OH and H(2)O. These cannot be definitive due to the lack of asymmetric O-H stretching frequencies (nu(OH)) which are spectral signatures of transferring protons. Born-Oppenheimer molecular dynamics (BOMD) simulations revealed that, when the thermal energy fluctuations and dynamics were included in the model calculations, the spectral signatures at nu(OH) approximately 1000 cm(-1) appeared. In continuum aqueous solution, the H-bond complex with incomplete water coordination at charged species turned out to be the only active transition state. Based on the assumption that the thermal energy fluctuations and dynamics could temporarily break the H-bonds linking the transition state complex and water molecules in the second hydration shell, elementary reactions of proton transfer were proposed. The present study showed that, due to the coupling among various vibrational modes, the discussions on proton transfer reactions cannot be made based solely on static proton transfer potentials. Inclusion of thermal energy fluctuations and dynamics in the model calculations, as in the case of BOMD simulations, together with systematic IR spectral analyses, have been proved to be the most appropriate theoretical approaches.

Thermodynamic studies of aqueous solutions of 2,2,2-cryptand at 298.15 K: enthalpy-entropy compensation, partial entropies, and complexation with K+ ions.

PubMed

Shaikh, Vasim R; Terdale, Santosh S; Ahamad, Abdul; Gupta, Gaurav R; Dagade, Dilip H; Hundiwale, Dilip G; Patil, Kesharsingh J

2013-12-19

The osmotic coefficient measurements for binary aqueous solutions of 2,2,2-cryptand (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8] hexacosane) in the concentration range of ~0.009 to ~0.24 mol·kg(-1) and in ternary aqueous solutions containing a fixed concentration of 2,2,2-cryptand of ~0.1 mol·kg(-1) with varying concentration of KBr (~0.06 to ~0.16 mol·kg(-1)) have been reported at 298.15 K. The diamine gets hydrolyzed in aqueous solutions and needs proper approach to obtain meaningful thermodynamic properties. The measured osmotic coefficient values are corrected for hydrolysis and are used to determine the solvent activity and mean ionic activity coefficients of solute as a function of concentration. Strong ion-pair formation is observed, and the ion-pair dissociation constant for the species [CrptH](+)[OH(-)] is reported. The excess and mixing thermodynamic properties (Gibbs free energy, enthalpy, and entropy changes) have been obtained using the activity data from this study and the heat data reported in the literature. Further, the data are utilized to compute the partial molal entropies of solvent and solute at finite as well as infinite dilution of 2,2,2-cryptand in water. The concentration dependent non-linear enthalpy-entropy compensation effect has been observed for the studied system, and the compensation temperature along with entropic parameter are reported. Using solute activity coefficient data in ternary solutions, the transfer Gibbs free energies for transfer of the cryptand from water to aqueous KBr as well as transfer of KBr from water to aqueous cryptand were obtained and utilized to obtain the salting constant (ks) and thermodynamic equilibrium constant (log K) values for the complex (2,2,2-cryptand:K(+)) at 298.15 K. The value of log K = 5.8 ± 0.1 obtained in this work is found to be in good agreement with that reported by Lehn and Sauvage. The standard molar entropy for complexation is also estimated for the 2,2,2-cryptand-KBr complex in aqueous medium.

Separations by supported liquid membrane cascades

DOEpatents

Danesi, P.R.

1983-09-01

The invention describes a new separation technique which leads to multi-stage operations by the use of a series (a cascade) of alternated carrier-containing supported-liquid cation exchanger extractant and a liquid anion exchanger extractant (or a neutral extractant) as carrier. The membranes are spaced between alternated aqueous electrolytic solutions of different composition which alternatively provide positively charged extractable species and negatively charged (or zero charged) extractable species, of the chemical species to be separated. The alternated aqueous electrolytic solutions in addition to providing the driving force to the process, simultaneously function as a stripping solution from one type of membrane and as an extraction-promoting solution for the other type of membrane. The aqueous electrolytic solution and the supported liquid membranes are arranged to provide a continuous process.

Quenching characteristics of bathocuproinedisulfonic acid, disodium salt in aqueous solution and copper sulfate plating solution

NASA Astrophysics Data System (ADS)

Koga, Toshiaki; Hirakawa, Chieko; Takeshita, Michinori; Terasaki, Nao

2018-04-01

Bathocuproinedisulfonic acid, disodium salt (BCS) is generally used to detect Cu(I) through a color reaction. We newly found BCS fluorescence in the visible blue region in an aqueous solution. However, the fluorescence mechanism of BCS is not well known, so we should investigate its fundamental information. We confirmed that the characteristics of fluorescence are highly dependent on the molecular concentration and solvent properties. In particular, owing to the presence of the copper compound, the fluorescence intensity extremely decreases. By fluorescence quenching, we observed that a copper compound concentration of 10-6 mol/L or less could easily be measured in an aqueous solution. We also observed BCS fluorescence in copper sulfate plating solution and the possibility of detecting monovalent copper by fluorescence reabsorption.

DISTRIBUTION OF URANIUM, ZIRCONIUM, NIOBIUM, RUTHENIUM AND CERIUM BETWEEN NITRIC ACID SOLUTIONS AND 10% TLA-5% OCTYL ALCOHOL/SHELL SOL-T

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

Lopez-Menchero, E.; Centeno, J.; Magni, G.

1962-03-01

The extraction of traces of Ru, Zr, Nb, Ce, and U at low concentrations (5 mg/l in aqueous solution) from nitric acid solutions using trilauryl amine (TLA) has been experimentally studied. TLA will eventually be used for final purification of plutonium. Room-temperature data on plutonium contaminant distribution between aqueous solutions of varying nitric acid concentrations and a Shellsol-T solution containing l0% TlA and 5% octyl alcohol are presented. Within the temperature and nitric acid concentration ranges tested, the extractability of uranium increased with increased acid concentrations, although acid concentration in the aqueous phase had no effect on the decontamination factorsmore » for the main fission products. (H.G.G.)« less

End-Member Formulation of Solid Solutions and Reactive Transport

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

Lichtner, Peter C.

2015-09-01

A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed tomore » correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.« less

Dynamics Control Approaches to Improve Vibratory Environment of the Helicopter Aircrew

NASA Astrophysics Data System (ADS)

Wickramasinghe, Viresh Kanchana

Although helicopter has become a versatile mode of aerial transportation, high vibration levels leads to poor ride quality for its passengers and aircrew. Undesired vibration transmitted through the helicopter seats have been known to cause fatigue and discomfort to the aircrew in the short-term as well as neck strain and back pain injuries due to long-term exposure. This research study investigated the use of novel active as well as passive methodologies integrated in helicopter seats to mitigate the aircrew exposure to high vibration levels. Due to significantly less certification effort required to modify the helicopter seat structure, application of novel technologies to the seat is more practical compared to flight critical components such as the main rotor to reduce aircrew vibration. In particular, this research effort developed a novel adaptive seat mount approach based on active vibration control technology. This novel design that incorporated two stacked piezoelectric actuators as active struts increases the bending stiffness to avoid the low frequency resonance while generating forces to counteract higher harmonic vibration peaks. A real-time controller implemented using a feed-forward algorithm based on adaptive notches counteracted the forced vibration peaks while a robust feedback control algorithm suppressed the resonance modes. The effectiveness of the adaptive seat mount system was demonstrated through extensive closed-loop control tests on a full-scale helicopter seat using representative helicopter floor vibration profiles. Test results concluded that the proposed adaptive seat mount approach based on active control technology is a viable solution for the helicopter seat vibration control application. In addition, a unique flight test using a Bell-412 helicopter demonstrated that the aircrew is exposed to high levels of vibration during flight and that the whole body vibration spectrum varied substantially depending on operating conditions as well as the aircrew configurations. This investigation also demonstrated the suitability of integrating novel energy absorbing cushion materials to the seat as a low cost solution to improve aircrew vibration suppression. Therefore, it was recommended to pursue certification of novel seat cushion materials as a near-term solution to mitigate undesirable occupational health hazards in helicopter aircrew due to vibration exposure.

Thin film superconductors and process for making same

DOEpatents

Nigrey, P.J.

1988-01-21

A process for the preparation of oxide superconductors from high-viscosity non-aqueous solution is described. Solutions of lanthanide nitrates, alkaline earth nitrates and copper nitrates in a 1:2:3 stoichiometric ratio, when added to ethylene glycol containing citric acid solutions, have been used to prepare highly viscous non-aqueous solutions of metal mixed nitrates-citrates. Thin films of these compositions are produced when a layer of the viscous solution is formed on a substrate and subjected to thermal decomposition.

CONTINUOUS CHELATION-EXTRACTION PROCESS FOR THE SEPARATION AND PURIFICATION OF METALS

DOEpatents

Thomas, J.R.; Hicks, T.E.; Rubin, B.; Crandall, H.W.

1959-12-01

A continuous process is presented for separating metal values and groups of metal values from each other. A complex mixture. e.g., neutron-irradiated uranium, can be resolved into component parts. In the present process the values are dissolved in an acidic solution and adjusted to the proper oxidation state. Thenceforth the solution is contacted with an extractant phase comprising a fluorinated beta -diketone in an organic solvent under centain pH conditions whereupon plutonium and zirconium are extracted. Plutonium is extracted from the foregoing extract with reducing aqueous solutions or under specified acidic conditions and can be recovered from the aqueous solution. Zirconium is then removed with an oxalic acid aqueous phase. The uranium is recovered from the residual original solution using hexone and hexone-diketone extractants leaving residual fission products in the original solution. The uranium is extracted from the hexone solution with dilute nitric acid. Improved separations and purifications are achieved using recycled scrub solutions and the "self-salting" effect of uranyl ions.