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Binary Mutual Diffusion Coefficients of Isoniazid Aqueous Solutions at (298.15 and 310.15) K

Ribeiro, Ana C. F.; Santos, Ana C. G.; Lobo, Victor M. M.; Veiga, Francisco J. B.; Cabral, Ana M. T. D. P. V.; Esteso, Miguel A.; Ortona, Ornella
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
ENG
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Binary mutual diffusion coefficients measured by the Taylor dispersion method in two different laboratories (University of Naples, Federico II, Italy, and University of Coimbra, Portugal) are reported for aqueous solutions of isoniazid at concentrations from (0.000 to 0.100) mol·dm−3 and at two temperatures (298.15 and 310.15) K. The hydrodynamic radii for the isoniazid in aqueous solution are calculated from the experimental results. In addition, the Hartley equation and the experimental diffusion coefficients are used to estimate activity coefficients for aqueous isoniazid at both temperatures

An assessment on the use of the debye-hückel equation for the thermodynamic modeling of aqueous systems containing polymers and salts

ALVES, K. C.Nascimento; PESSÔA FILHO, P. A.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica
ENG
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In this work, a study on the role of the long-range term of excess Gibbs energy models in the modeling of aqueous systems containing polymers and salts is presented. Four different approaches on how to account for the presence of polymer in the long-range term were considered, and simulations were conducted considering aqueous solutions of three different salts. The analysis of water activity curves showed that, in all cases, a liquid-phase separation may be introduced by the sole presence of the polymer in the long-range term, regardless of how it is taken into account. The results lead to the conclusion that there is no single exact solution for this problem, and that any kind of approach may introduce inconsistencies.; CAPES, CNPq and FAPESP

AN ASSESSMENT ON THE USE OF THE DEBYE-HUCKEL EQUATION FOR THE THERMODYNAMIC MODELING OF AQUEOUS SYSTEMS CONTAINING POLYMERS AND SALTS

ALVES, K. C. Nascimento; PESSOA FILHO, P. A.
Fonte: BRAZILIAN SOC CHEMICAL ENG Publicador: BRAZILIAN SOC CHEMICAL ENG
Tipo: Artigo de Revista Científica
ENG
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In this work, a study on the role of the long-range term of excess Gibbs energy models in the modeling of aqueous systems containing polymers and salts is presented. Four different approaches on how to account for the presence of polymer in the long-range term were considered, and simulations were conducted considering aqueous solutions of three different salts. The analysis of water activity curves showed that, in all cases, a liquid-phase separation may be introduced by the sole presence of the polymer in the long-range term, regardless of how it is taken into account. The results lead to the conclusion that there is no single exact solution for this problem, and that any kind of approach may introduce inconsistencies.; CAPES; CNPq; FAPESP

Investigação por eletroforese capilar com detecção condutométrica sem contato sobre a formação e as propriedades de monoalquil carbonatos em meio aquoso; Investigation by capillary electrophoresis with contactless conductivity detection on the formation and properties of monoalkyl carbonates in aqueous medium

Vidal, Denis Tadeu Rajh
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 24/11/2011 PT
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A formação dos monoalquil carbonatos (MACs) em meio aquoso - produzidos pela reação de um álcool e bicarbonato foi investigada por eletroforese capilar (CE) com detecção condutométrica sem contato (C4D). Foram estudadas ao todo 29 substâncias, das quais 25 apresentaram formação de adutos aniônicos monocarregados e 2 delas, adutos aniônicos com dupla carga. A eletroforese capilar proporcionou a obtenção de medidas de propriedades físico-químicas. Através do tempo de migração, foram obtidos mobilidade, coeficiente de difusão e raio iônico hidratado. Para os n-álcoois de 1 a 5 átomos de carbono, os adutos apresentaram raio iônico hidratado entre 216 pm e 310 pm. Os MACs têm raio iônico proporcional ao do álcool gerador, sendo sistematicamente maiores devidos à anexação do grupo carbonato. Quando comparado a ácidos carboxílicos de cadeia carbônica similar, os MACs possuem menor raio iônico hidratado. A obtenção dos valores da cinética de formação e hidrólise foi possível pela utilização de dupla detecção condutométrica, a qual permitia determinar a concentração do MAC em dois momentos diferentes ao longo da coluna. Devido à impossibilidade de uma calibração direta - já que os sais de MACs se decompõem em água - foi introduzida uma nova técnica de calibração que dispensa o uso de uma solução padrão do analito em favor de uma com espécie de mobilidade similar. As constantes cinética e termodinâmica foram comparadas com aquelas disponíveis na literatura...

Degradação de profenofós em solução aquosa e em ervilhas processadas por feixe de elétrons e a síntese de polímeros impressos para extração seletiva desse pesticida; Degradation of profenofos in aqueous solution and peas by electron beam processed and synthesis of imprinted polymers for selective extraction of this pesticide

Rodrigues, Flavio Thihara
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 10/04/2015 PT
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Profenofós é um organofosforado empregado como inseticida e acaricida amplamente utilizado no Brasil para o controle de pragas de cebolas, milho, soja, café, tomate, algodão, feijão, batata e outros. A irradiação é um processo empregado em todo o mundo e recomendada por diversos órgãos de saúde para a conservação de alimentos. A radiação ionizante utiliza raios gama, raios X ou aceleradores de elétrons e tem sido aplicada para eliminar ou reduzir a ação de agentes patogênicos e contribuir para aumentar o tempo de estocagem de vários alimentos. Os objetivos desse trabalho foram: (a) avaliar a degradação de soluções aquosas de profenofós submetidas à radiação ionizante, identificar e quantificar a formação de novos produtos por GC-MS; (b) analisar o efeito de feixe de elétrons em ervilhas inoculadas com soluções aquosas de profenofós; (c) sintetizar Polímeros Molecularmente Impressos (MIP) e Sílica Impressa Molecularmente (MIS), posteriormente, caracterizar os adsorventes em fase sólida e verificar sua seletividade para profenofós. O tratamento com aceleradores de elétrons com dose 31,6 kGy promoveu a formação de um novo produto de degradação e redução de 93,40 % de profenofós em soluções aquosas. Em ervilhas inoculadas com 1 μg de profenofós submetidas à radiação ionizante de 30...

Extraction of added-value products from biomass using ionic liquids; Extração de produtos de valor acrescentado a partir de biomassa utilizando líquidos iónicos

Silva, Ana Filipa Martins Cláudio da
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
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The main purpose of this thesis is to investigate the potential of ionic liquids (ILs) as a new class of extractive solvents for added-value products from biomass. These include phenolic compounds (vanillin, gallic, syringic and vanillic acids), alkaloids (caffeine) and aminoacids (L-tryptophan). The interest on these natural compounds relies on the wide variety of relevant properties shown by those families and further application in the food, cosmetic and pharmaceutical industries. Aiming at developping more benign and effective extraction/purification techniques than those used, a comprehensive study was conducted using aqueous biphasic systems (ABS) composed of ILs and inorganic/organic salts. In addition, ILs were characterized by a polarity scale, using solvatochromic probes, aiming at providing prior indications on the ILs affinity for particular added-value products. Solid-liquid (S-L) extractions from biomass and using aqueous solution of ILs were also investigated. In particular, and applying and experimental factorial design to optimize the operational conditions, caffeine was extracted from guaraná seeds and spent coffee. With both types of extractions it was found that it is possible to recover the high-value compounds and to recycle the IL and salt solutions. Finally...

An assessment on the use of the debye-hückel equation for the thermodynamic modeling of aqueous systems containing polymers and salts

Alves,K. C.Nascimento; Pessôa Filho,P. A.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 EN
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In this work, a study on the role of the long-range term of excess Gibbs energy models in the modeling of aqueous systems containing polymers and salts is presented. Four different approaches on how to account for the presence of polymer in the long-range term were considered, and simulations were conducted considering aqueous solutions of three different salts. The analysis of water activity curves showed that, in all cases, a liquid-phase separation may be introduced by the sole presence of the polymer in the long-range term, regardless of how it is taken into account. The results lead to the conclusion that there is no single exact solution for this problem, and that any kind of approach may introduce inconsistencies.

Empirical Correlation Between Hydrophobic Free Energy and Aqueous Cavity Surface Area

Reynolds, Jacqueline A.; Gilbert, David B.; Tanford, Charles
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1974 EN
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The unitary free energy of transfer of a hydrocarbon molecule from a hydrocarbon solvent to an aqueous medium is a measure of the hydrophobic interaction in the aqueous medium. We have reexamined available data on this phenomenon and have confirmed that the free energy for saturated hydrocarbons is proportional to the surface area of the cavity created by the solute in the aqueous solution, with the same proportionality constant for linear, branched, and cyclic hydrocarbon molecules. The numerical value of the proportionality constant is uncertain because absolute and self-consistent area measurements are not available. We estimate that it falls between 20 and 25 cal/mole per Å2 at 25° (for areas measured at the distance of closest approach of water molecules), which is significantly less than the figure of 33 cal/mole per Å2 that has been assigned to the same parameter by Hermann [J. Phys. Chem. 76, 2754-2759 (1972)]. A small discrepancy exists when similar data for homologous series of alkyl derivatives are compared with results based on hydrocarbons themselves, and possible reasons for it are discussed.

Decomposition of 2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one in Aqueous Solutions 1

Woodward, Michael D.; Corcuera, Luis J.; Helgeson, John P.; Upper, Christen D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1978 EN
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Cyclic hydroxamic acids present in some species of Gramineae have been reported to be important in resistance of these plants to fungi and insects. Since the nonglucosylated forms of these acids are unstable in aqueous solution, in vitro methods for the measurement of their antibiotic properties have been difficult. Kinetics of the decomposition of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), the major hydroxamate in corn (Zea mays L.) extracts, were studied in buffered aqueous solutions from pH 5 to 7.5 at temperatures from 20 to 80 C. Kinetics were apparently first order under all conditions tested; energies of activation (24 to 28 kcal/mol) were nearly pH-independent. DIMBOA decomposed rapidly (half-life = 5.3 hours at 28 C, pH 6.75) relative to the time required for many procedures which have been used to demonstrate the biological activity of DIMBOA. The rate of disappearance of inhibitory activity of DIMBOA toward Erwinia carotovora was indistinguishable from the rate of decomposition of DIMBOA. Contrary to reports, yields of 6-methoxy-2-benzoxazolinone (MBOA) were not quantitative. Gas-liquid chromatography analytical procedures were developed for quantitation of trimethylsilyl and acetyl derivatives of MBOA. As measured by ultraviolet spectroscopy and/or gas-liquid chromatography...

A stopped-flow apparatus for infrared spectroscopy of aqueous solutions.

White, A J; Drabble, K; Wharton, C W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/03/1995 EN
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IR spectroscopy has been widely applied in the study of photo-activated biological processes such as photosynthesis, but has not been applied to the study of reacting systems which require rapid mixing of aqueous solutions. This has been due in part to the high pressure needed to make an aqueous solution flow rapidly through the 50 microns optical pathlength between the plates in an IR cuvette suitable for use with 2H2O and the high viscosity of the concentrated protein solutions required to generate measurable IR signals. An apparatus, based largely on conventional stopped-flow technology, is described which achieves mixing well within the time-resolved performance (approximately 40 ms) of modern Fourier-transform IR (FTIR) spectrometers, since the dead time of the mixing device is approximately 15 ms. It has proved possible to achieve efficient mixing by using a simple six-jet mixing device. This is probably at least in part because of the high back pressure which develops when aqueous fluid is passed rapidly through the short pathlength of the cuvette and which promotes turbulent flow. Several examples of measurements of the deacylation of acylchymotrypsins are provided which demonstrate the operation of the apparatus in conjunction with a spectrometer capable of scanning at four scans/s. For cinnamoyl-chymotrypsin...

Extraction of steroidal glucosiduronic acids from aqueous solutions by anionic liquid ion-exchangers

Mattox, Vernon R.; Litwiller, Robert D.; Goodrich, June E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1972 EN
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A pilot study on the extraction of three steroidal glucosiduronic acids from water into organic solutions of liquid ion-exchangers is reported. A single extraction of a 0.5mm aqueous solution of either 11-deoxycorticosterone 21-glucosiduronic acid or cortisone 21-glucosiduronic acid with 0.1m-tetraheptylammonium chloride in chloroform took more than 99% of the conjugate into the organic phase; under the same conditions, the very polar conjugate, β-cortol 3-glucosiduronic acid, was extracted to the extent of 43%. The presence of a small amount of chloride, acetate, or sulphate ion in the aqueous phase inhibited extraction, but making the aqueous phase 4.0m with ammonium sulphate promoted extraction strongly. An increase in the concentration of ion-exchanger in the organic phase also promoted extraction. The amount of cortisone 21-glucosiduronic acid extracted by tetraheptylammonium chloride over the pH range of 3.9 to 10.7 was essentially constant. Chloroform solutions of a tertiary, a secondary, or a primary amine hydrochloride also will extract cortisone 21-glucosiduronic acid from water. The various liquid ion exchangers will extract steroidal glucosiduronic acid methyl esters from water into chloroform, although less completely than the corresponding free acids. The extraction of the glucosiduronic acids from water by tetraheptylammonium chloride occurs by an ion-exchange process; extraction of the esters does not involve ion exchange.

Partitioning of octyl glucoside between octyl glucoside/phosphatidylcholine mixed aggregates and aqueous media as studied by isothermal titration calorimetry.

Opatowski, E; Kozlov, M M; Lichtenberg, D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1997 EN
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Stepwise dilution of lipid-surfactant mixed micelles first results in extraction of surfactant from the mixed micelles into the aqueous medium. Subsequently mixed micelles transform into vesicles, within a range of compositions that corresponds to equilibrium coexistence between these two types of aggregates. Further dilution results in extraction of surfactant from the resultant mixed vesicles. In the present study, we have investigated the heat evolution of these processes, as they occur in mixed systems composed of egg phosphatidylcholine (PC) and the nonionic surfactant octylglucoside (OG). A combined use of isothermal titration calorimetry (ITC) and photon correlation spectroscopy (PCS), capable of monitoring phase transformations, revealed that 1) The sum of all of the studied processes (i.e., extraction of OG from mixed micelles and vesicles and the phase transformation) is isocaloric at approximately 40 degrees C throughout the whole dilution. At lower temperatures, all of the dilution steps are exothermic, whereas at higher temperatures all of them are endothermic. 2) At all temperatures, the absolute value of the heat associated with each dilution step within the range of coexistence of micelles and vesicles is almost constant and larger than in either the micellar or the vesicular range. We give an interpretation of these calorimetric data in terms of the relationship between the composition of the mixed aggregates Re and the aqueous concentration of surfactant monomers Dw. Assuming that the main contribution to the heat evolution is due to extraction of surfactant from mixed aggregates to the aqueous solution...

Origin of Supercharging in Electrospray Ionization of Noncovalent Complexes from Aqueous Solution

Sterling, Harry J.; Williams, Evan R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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The use of m-nitrobenzyl alcohol (m-NBA) to enhance charging of noncovalent complexes formed by electrospray ionization from aqueous solutions was investigated. Addition of up to 1% m-NBA can result in a significant increase in the average charging of complexes, ranging from ~13% for the homo-heptamer of NtrC4-RC (317 kDa; maximum charge state increases from 42+ to 44+) to ~49% for myoglobin (17.6 kDa; maximum charge state increases from 9+ to 16+). Charge state distributions of larger complexes obtained from heated solutions to which no m-NBA was added are remarkably similar to those containing small amounts of m-NBA. Dissociation of the complexes through identical channels both upon addition of higher concentrations of m-NBA and heating is observed. These results indicate that the enhanced charging upon addition of m-NBA to aqueous electrospray solutions is a result of droplet heating owing to the high boiling point of m-NBA, which results in a change in the higher-order structure and/or dissociation of the complexes. For monomeric proteins and small complexes, the enhancement of charging is lower for heated aqueous solutions than from solutions with m-NBA because rapid folding of proteins from heated solutions that do not contain m-NBA can occur after the electrospray droplet is formed and is evaporatively cooled.

Paul trapping of charged particles in aqueous solution

Guan, Weihua; Joseph, Sony; Park, Jae Hyun; Krstić, Predrag S.; Reed, Mark A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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We experimentally demonstrate the feasibility of an aqueous Paul trap using a proof-of-principle planar device. Radio frequency voltages are used to generate an alternating focusing/defocusing potential well in two orthogonal directions. Individual charged particles are dynamically confined into nanometer scale in space. Compared with conventional Paul traps working in frictionless vacuum, the aqueous environment associated with damping forces and thermally induced fluctuations (Brownian noise) exerts a fundamental influence on the underlying physics. We investigate the impact of these two effects on the confining dynamics, with the aim to reduce the rms value of the positional fluctuations. We find that the rms fluctuations can be modulated by adjusting the voltages and frequencies. This technique provides an alternative for the localization and control of charged particles in an aqueous environment.

Aqueous Viscosity Is the Primary Source of Friction in Lipidic Pore Dynamics

Ryham, Rolf; Berezovik, Irina; Cohen, Fredric S.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em 21/12/2011 EN
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A new theory, to our knowledge, is developed that describes the dynamics of a lipidic pore in a liposome. The equations of the theory capture the experimentally observed three-stage functional form of pore radius over time—stage 1, rapid pore enlargement; stage 2, slow pore shrinkage; and stage 3, rapid pore closure. They also show that lipid flow is kinetically limited by the values of both membrane and aqueous viscosity; therefore, pore evolution is affected by both viscosities. The theory predicts that for a giant liposome, tens of microns in radius, water viscosity dominates over the effects of membrane viscosity. The edge tension of a lipidic pore is calculated by using the theory to quantitatively account for pore kinetics in stage 3, rapid pore closing. This value of edge tension agrees with the value as standardly calculated from the stage of slow pore closure, stage 2. For small, submicron liposomes, membrane viscosity affects pore kinetics, but only if the viscosity of the aqueous solution is comparable to that of distilled water. A first-principle fluid-mechanics calculation of the friction due to aqueous viscosity is in excellent agreement with the friction obtained by applying the new theory to data of previously published experimental results.

Anions dramatically enhance proton transfer through aqueous interfaces

Mishra, Himanshu; Enami, Shinichi; Nielsen, Robert J.; Hoffmann, Michael R.; Goddard, William A.; Colussi, Agustín J.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Proton transfer (PT) through and across aqueous interfaces is a fundamental process in chemistry and biology. Notwithstanding its importance, it is not generally realized that interfacial PT is quite different from conventional PT in bulk water. Here we show that, in contrast with the behavior of strong nitric acid in aqueous solution, gas-phase HNO3 does not dissociate upon collision with the surface of water unless a few ions (> 1 per 106 H2O) are present. By applying online electrospray ionization mass spectrometry to monitor in situ the surface of aqueous jets exposed to HNO3(g) beams we found that production increases dramatically on > 30-μM inert electrolyte solutions. We also performed quantum mechanical calculations confirming that the sizable barrier hindering HNO3 dissociation on the surface of small water clusters is drastically lowered in the presence of anions. Anions electrostatically assist in drawing the proton away from lingering outside the cluster, whose incorporation is hampered by the energetic cost of opening a cavity therein. Present results provide both direct experimental evidence and mechanistic insights on the counterintuitive slowness of PT at water-hydrophobe boundaries and its remarkable sensitivity to electrostatic effects.

Non-aqueous microchip electrophoresis for characterization of lipid biomarkers

Gibson, Larry R.; Bohn, Paul W.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 06/06/2013 EN
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In vivo measurements of lipid biomarkers are hampered by their low solubility in aqueous solution, which limits the choices for molecular separations. Here, we introduce non-aqueous microchip electrophoretic separations of lipid mixtures performed in three-dimensional hybrid nanofluidic/microfluidic polymeric devices. Electrokinetic injection is used to reproducibly introduce discrete femtolitre to picolitre volumes of charged lipids into a separation microchannel containing low (100 μM–10 mM) concentration tetraalkylammonium tetraphenylborate background electrolyte (BGE) in N-methylformamide, supporting rapid electro-osmotic fluid flow in polydimethylsiloxane microchannels. The quality of the resulting electrophoretic separations depends on the voltage and timing of the injection pulse, the BGE concentration and the electric field strength. Injected volumes increase with longer injection pulse widths and higher injection pulse amplitudes. Separation efficiency, as measured by total plate number, N, increases with increasing electric field and with decreasing BGE concentration. Electrophoretic separations of binary and ternary lipid mixtures were achieved with high resolution (Rs ∼ 5) and quality (N > 7.7 × 106 plates m−1). Rapid in vivo monitoring of lipid biomarkers requires high-quality separation and detection of lipids downstream of microdialysis sample collection...

Predicting binding free energies in solution

Jensen, Jan H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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Recent predictions of absolute binding free energies of host-guest complexes in aqueous solution using electronic structure theory have been encouraging for some systems, while other systems remain problematic for others. In paper I summarize some of the many factors that could easily contribute 1-3 kcal/mol errors at 298 K: three-body dispersion effects, molecular symmetry, anharmonicity, spurious imaginary frequencies, insufficient conformational sampling, wrong or changing ionization states, errors in the solvation free energy of ions, and explicit solvent (and ion) effects that are not well-represented by continuum models. While I focus on binding free energies in aqueous solution the approach also applies (with minor adjustments) to any free energy difference such as conformational or reaction free energy differences or activation free energies in any solvent.

The hydration of Cu2+: Can the Jahn-Teller effect be detected in liquid solution?

Chaboy, Jesús; Muñoz-Páez, Adela; Merkling, Patrick J.; Sánchez Marcos, Enrique
Fonte: American Institute of Physics Publicador: American Institute of Physics
Tipo: Artículo Formato: 691294 bytes; application/pdf
ENG
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9 pages, 7 figures, 1 table.-- PACS 78.70.Dm 61.20.-p 61.25.Em; The long elusive structure of Cu(II) hydrate in aqueous solutions, classically described as a Jahn-Teller distorted octahedron and recently proposed to be a fivefold coordination structure [Pasquarello et al., Science 291, 856 (2001)], has been probed with x-ray-absorption spectroscopy by performing a combined theoretical and experimental analysis. Two absorption channels were needed to obtain a proper reproduction of the x-ray-absorption near-edge structure (XANES) region spectrum, as already observed in other Cu(II) complexes [Chaboy et al., Phys. Rev. B 71, 134208 (2005)]. The extended x-ray-absorption fine-structure (EXAFS) spectrum was analyzed as well within this approach. Quite good reproductions of both XANES and EXAFS spectra were attained for several distorted and undistorted structures previously proposed. Nevertheless, there is not a clearly preferred structure among those including four-, five-, and sixfold coordinated Cu(II) ions. Taking into account our results, as well as many more from several other authors using different techniques, the picture of a distorted octahedron for the Cu(II) hexahydrate in aqueous solution, paradigm of the Jahn-Teller effect...

Near-infrared chemiluminescence from the oxidation of ammonia in aqueous alkaline solution

Francis, Paul; Barnett, Neil; Smith, Trevor; Spizzirri, Paul; Wang, Xue Qin; Krausz, Elmars
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
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The chemiluminescent oxidation of ammonia with hypobromite in aqueous alkaline solution evokes a broadly distributed emission in the near-infrared region, with intensity maxima at 1055 nm and 1270 nm.