Effect of SO(2) on the Transport Properties of an Imidazolium Ionic Liquid and Its Lithium Solution

Transport coefficients have been measured as a function of the concentration of sulfur dioxide, SO(2), dissolved in 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)-imide, [BMMI][Tf(2)N], as well as in its lithium salt solution, Li[Tf(2)N]. The SO(2) reduces viscosity and density and increases conductivity and diffusion coefficients in both the neat [BMMI] [Tf(2)N] and the [BMMI][Tf(2)N]-Li[Tf(2)N] solution. The conductivity enhancement is not assigned to a simple viscosity effect; the weakening of ionic interactions upon SO(2) addition also plays a role. Microscopic details of the SO(2) effect were unraveled using Raman spectroscopy and molecular dynamics (MD) simulations. The Raman spectra suggest that the Li(+)-[Tf(2)N] interaction is barely affected by SO(2), and the SO(2)-[Tf(2)N] interaction is weaker than previously observed in an investigation of an ionic liquid containing the bromide anion. Transport coefficients calculated by MD simulations show the same trend as the experimental data with respect to SO(2) content. The MD simulations provide structural information on SO(2) molecules around [Tf(2)N], in particular the interaction of the sulfur atom of SO(2) with oxygen and fluorine atoms of the anion. The SO(2)-[BMMI] interaction is also important because the [BMMI] cations with above-average mobility have a larger number of nearest-neighbor SO(2) molecules.

Dinuclear Azide-Bridged Copper(II) Complex as Building Block for the Assembly of a 2D-Supramolecular Array

A novel Schiff base-copper(II) complex [Cu(2)L(2)(N(3))(2)](ClO(4))(2) 1, where L = (4-imidazolyl)ethylene-2-amino-1-ethylpyridine (apyhist), containing azide-bridges between adjacent copper ions in a dinuclear arrangement was isolated and characterized both in the solid state and in solution by X-ray crystallography and different spectroscopic techniques. Azide binding constants were estimated from titrations of the precursor [CuL(H(2)O)(2)](2+) solutions with sodium azide, giving rise to the azido-bridged species, [Cu(2)L(2)(N(3))(2)](2+). Raman spectra showed asymmetric stretching band at 2060 cm(-1), indicating the presence of azido ligands with a symmetric mu(1,) (1) binding geometry. EPA spectra, in frozen methanol/water solutions at 77 K, exhibited characteristic features of copper centers in tetragonal pyramidal coordination geometry, exhibiting magnetic interactions between them. Further, in solid state, two different values for magnetic coupling in this species were obtained, J/k = -(5.14 +/- 0.02) cm(-1) attributed to the mu(1, 1) azide-bridge mode, and J`z`/k = -(2.94 +/- 0.11) cm(-1) for the interaction between dinuclear moieties via water/perchorate bridges. Finally, an attempt was made to correlate structure and magnetic data for this dinuclear asymmetric end-on azido bridged-copper(II) 1 complex with those of another correlated dinuclear system, complex [Cu(2)L(2)Cl(2)](ClO(4))(2) 2, containing the same tridentate diimine ligand, but with chloro-bridged groups between the copper centres.

Intralamellar structural modifications related to the proton exchanging in K(4)Nb(6)O(17) layered phase

Basic structural aspects about the layered hexaniobate of K(4)Nb(6)O(17) composition and its proton-exchanged form were investigated mainly by spectroscopic techniques. Raman spectra of hydrous K(4)Nb(6)O(17) and H(2)K(2)Nb(6)O(17)center dot H(2)O show significant modifications in the 950-800 cm(-1) region (Nb-O stretching mode of highly distorted NbO(6) octahedra). The band at 900 cm(-1) shifts to 940 cm(-1) after the replacement of K(+) ion by proton. Raman spectra of the original materials and the related deuterated samples are similar suggesting that no isotopic effect occurs. Major modifications were observed when H(2)K(2)Nb(6)O(17) was dehydrated: the relative intensity of the band at 940 cm(-1) decreases and new bands seems to be present at about 860-890 cm(-1). The H(+) ions should be shielded by the hydration sphere what preclude the interaction with the layers. Removing the water molecules, H(+) ions can establish a strong interaction with oxygen atoms, decreasing the bond order of Nb-O linkage. X-ray absorption near edge structure studies performed at Nb K-edge indicate that the niobium coordination number and oxidation state remain identical after the replacement of potassium by proton. From the refinement of the fine structure, it appears that the Nb-Nb coordination shell is divided into two main contributions of about 0.33 and 0.39 nm, and interestingly the population, i.e., the number of backscattering atoms is inversed between the two hexaniobate materials. 2009 Elsevier Ltd. All rights reserved.

Lithium Ion Electro-Insertion and Spectroelectrochemical Properties of Films from Hexaniobate

Layer-by-layer (LbL) films from K(2)Nb(6)O(17)(2-) and polyallylamine (PAH) and dip-coating films of H(2)K(2)Nb(6)O(17) were prepared on a fluorine-doped tin-oxide (FTO)-coated glass. The atomic force microscopy (AFM) images were carried out for morphological characterization of both materials. The real surface area and the roughness factor were determined on the basis of pseudocapacitive processes involved in the electroreduction/electrooxidation of gold layers deposited on these films. Next, lithium ion insertion into these materials was examined by means of electrochemical and spectroelectrochemical measurements. More specifically, cyclic voltammetry and current pulses under visible light beams were used to investigate mass transport and chromogenic properties. The lithium ion diffusion coefficient (D(Li)) within the LbL matrix is significantly higher than that within the dip-coating film, ensuring high storage capacity of lithium ions in the self-assembled electrode. Contrary to the LbL film, the potentiodynamic profile of absorbance change (Delta A) as a function of time is not similar to that obtained in the case of current density for the dip-coating film. Aiming at analyzing the rate of the coloration front associated with lithium ion diffusion, a spectroelectrochemical method based on the galvanostatic intermittent titration technique (GITT) was employed so as to determine the ""optical"" diffusion coefficient (D(op)). In the dip-coating film, the method employed here revealed that the lithium ion rate is higher in diffusion pathways formed from K(2)Nb(6)O(17)(2-) sites that contribute more significantly to Delta A. Meanwhile, the presence of PAH contributed to the increased ionic mobility in diffusion pathways in the LbL film, with low contribution to the electrochromic efficiency. These results aided a better understanding of the potentiodynamic profile of the temporal change of absorbance and current density during the insertion/deinsertion of lithium ions into the electrochromic materials.

Raman spectroscopy of a sulfur dioxide visual sensor: The origin of the two colors in the solid sample

The vibrational spectroscopic characterization of a sulfur dioxide visual sensor was carried out using a Raman microscope system. It was observed the formation of two distinct complexes, that were characterized by the position and relative intensities of the bands assigned to the symmetric stretching, nu(s)(SO(2)),of the linked SO(2) molecules. In fact, in the yellowish orange complex, that corresponds to the 1:1 stoichiometry, only one band is observed, assigned to nu(s)(SO(2)) at ca. 1080 cm-(1) and, in the deep red complex, that corresponds to the 1:2 complex, at ca. 1070 and 1090 cm(-)1 are observed. The variation of the relative intensities of the bands assigned to nu(s)(SO(2)) present in the Ni(II)center dot SO(2) complex, in different points of the sample, shows clearly the requirement of the Raman microscope in the vibrational characterization of this kind of molecular sensor. (C) 2008 Elsevier B.V. All rights reserved.

Raman, IR, UV-vis and EPR characterization of two copper dioxolene complexes derived from L-dopa and dopamine

The anionic complexes [Cu(L(1-))(3)](1-), L(-) = dopasemiquinone or L-dopasemiqui none, were prepared and characterized. The complexes are stable in aqueous solution showing intense absorption bands at ca. 605 nm for Cu(II)-L-dopasemiquinone and at ca. 595 nm for Cu(II)-dopasemiquinone in the UV-vis spectra, that can be assigned to intraligand transitions. Noradrenaline and adrenaline, under the same reaction conditions, did not yield Cu-complexes, despite the bands in the UV region showing that noradrenaline and adrenaline were oxidized during the process. The complexes display a resonance Raman effect, and the most enhanced bands involve ring modes and particularly the vCC + vCO stretching mode at ca. 1384 cm(-1). The free radical nature of the ligands and the oxidation state of the Cu(II) were confirmed by the EPR spectra that display absorptions assigned to organic radicals with g= 2.0005 and g = 2.0923, and for Cu(II) with g = 2.008 and g = 2.0897 for L-dopasemiquinone and dopasemiquinone, respectively. The possibility that dopamine and L-dopa can form stable and aqueous-soluble copper complexes at neutral pH, whereas noradrenaline and adrenaline cannot, may be important in understanding how Cu(II)-dopamine crosses the cellular membrane as proposed in the literature to explain the role of copper in Wilson disease. (c) 2008 Elsevier B.V. All rights reserved.

The electronic delocalization in para-substituted beta-nitrostyrenes probed by resonance Raman spectroscopy and quantum-chemical calculations

The electronic (UV-vis) and resonance Raman (RR) spectra of a series of para-substituted trans-beta-nitrostyrenes were investigated to determine the influence of the electron donating properties of the substituent (X = H, NO2, COOH, Cl, OCH3, OH, N(CH3)(2), and O-) on the extent of the charge transfer to the electron-withdrawing NO2 group directly linked to the ethylenic (C=C) unit. The Raman spectra and quantum chemical calculations show clearly the correlation of the electron donating power of the X group with the wavenumbers of the nu(s)(NO2) and nu (C=C)(sty) normal modes. In conditions of resonance with the lowest excited electronic state, one observes for X = OH and N(CH3)2 that the symmetric stretching of the NO2. nu(s)(NO2), is the most substantially enhanced mode, whereas for X = O-, the chromophore is extended over the whole molecule, with substantial enhancement of several carbon backbone modes. Copyright (c) 2008 John Wiley & Sons, Ltd.

Compatibility and decomposition kinetics studies of prednicarbate alone and associated with glyceryl stearate

In this work, TG/DTG and DSC techniques were used to the determination of thermal behavior of prednicarbate alone and associated with glyceryl stearate excipient ( 1: 1 physical mixture). TG/DTG curves obtained for the binary mixture showed a reduction of approximately 37 degrees C to the thermal stability of drug (T(dm/dt-0) (Max)(DTG)). The disappearance of stretching band at 1280 cm(-1) (nu(as) C-O, carbonate group) and the presence of streching band with less intensity at 1750 cm(-1) (nu(s) C-O, ester group) in IR spectrum obtained to the binary mixture submitted at 220 degrees C, when compared with IR spectrum of drug submitted to the same temperature, confirmed the chemical interaction between these substances due to heating. Kinetics parameters of decomposition reaction of prednicarbate were obtained using isothermal (Arrhenius equation) and non-isothermal (Ozawa) methods. The reduction of approximately 45% of activation energy value (E(a)) to the first step of thermal decomposition reaction of drug in the 1:1 (mass/mass) physical mixture was observed by both kinetics methods.

Raman spectra of acetonitrile in imidazolium ionic liquids

Raman spectra of dilute solutions of acetonitrile in ionic liquids reveal the characteristic features of ionic liquids` polarity. This is accomplished by investigating the Raman bandshape of the nu (CN) band, corresponding to the CN stretching mode of CH(3)CN, which is a very sensitive probe of the local environment. The amphiphilic nature of the CH(3)CN molecule allows us to observe the effect of electron pair acceptor and electron pair donor characteristics on ionic liquids. It has been found that the overall polarity of nine different ionic liquids based on 1-alkyl-3-methylimidazolium cations is more dependent on the anion than cation. The observed wavenumber shift of the nu (CN) band of CH(3)CN in ionic liquids containing alkylsulfate anions agrees with the significant different values previously measured for the dielectric constant of these ionic liquids. The conclusions obtained from the analysis of the nu (CN) band were corroborated by the analysis of the symmetric nu(1) (CD(3)) stretching mode of deuterated acetonitrile in different ionic liquids. Copyright (C) 2010 John Wiley & Sons, Ltd.

Effect of the chain length in the structure of imidazolic ionic liquids and dimethylformamide solutions probed by Raman spectroscopy

The Raman band assigned to the nu(C=O)mode in N,N-dimethylformamide (at ca. 1660 cm(-1)) was used as a probe to study a group of ionic liquids 1-alkyl-3-methylimidazolium bromide ([C(n)Mlm]Br) with different alkyl groups (n = 2, 4, 6, 8 and 10 carbons) in binary equimolar binary mixtures with dimethylformamide. Due to the high electric dipole moment of the group C=O, there is a substantial coupling between adjacent molecules in the solution, and the corresponding Raman band involves both vibrational and reorientational modes. Different chain lengths of the ILs lead to different extents of the uncoupling of adjacent molecules of dimethylformamide, resulting in different shifts for this band in the mixtures. Information about the organization of ionic liquids in solution was obtained and a model of aggregation for these systems is proposed. (C) 2010 Elsevier B.V. All rights reserved.

Thermodynamics and Lithium Intercalation in CeO(2)-TiO(2) Thin Film

The kinetics and the thermodynamics of electrochemical intercalation of lithium into CeO(2)-TiO(2) films prepared by the sol-gel process were studied by galvanostatic intermittent titration technique (GITT) as function of the depth of lithium intercalation. The open-circuit-potential versus x in Li(x)(CeO(2)-TiO(2)) curve consists of two straight lines with different slopes, one in the range of 0.03 <= x <= 0.09 and the other of 0.09 < x <= 0.15. The standard Gibbs energy for lithium intercalation Delta G(1)(0) was 6kJ/mol for x = 0.09 in Li(x)(CeO(2)-TiO(2)) at room temperature. The chemical diffusion coefficient value, D(Li+), of lithium intercalation into thin film oxide was 2.14.10(-11) cm(2)/s at x = 0.15, and the value of the component diffusion coefficient D(Li+),(k) was about one order of magnitude lower than the coefficient of chemical diffusion.

A theoretical study on the XeF(2) molecule

A relativistic four-component study was performed for the XeF(2) molecule by using the Dirac-Coulomb (DC) Hamiltonian and the relativistic adapted Gaussian basis sets (RAGBSs). The comparison of bond lengths obtained showed that relativistic effects on this property are small (increase of only 0.01 angstrom) while the contribution of electron correlation, obtained at CCSD(T) or CCSD-T levels, is more important (increase of 0.05 angstrom). Electron correlation is also dominant over relativistic effects for dissociation energies. Moreover, the correlation-relativity interaction is shown to be negligible for these properties. The electron affinity, the first ionization potential and the double ionization potential are obtained by means of the Fock-space coupled cluster (FSCC) method, resulting in DC-CCSD-T values of 0.3 eV, 12.5 eV and 32.3 eV, respectively. Vibrational frequencies and some anharmonicity constants were also calculated under the four-component formalism by means of standard perturbation equations. All these molecular properties are, in general, ill satisfactory agreement with available experimental results. Finally, a partition in terms of charge-charge flux-dipole flux (CCFDF) contributions derived by means of the quantum theory of atoms in molecules (QTAIM) in non-relativistic QCISD(FC)/3-21G* calculations was carried out for XeF(2) and KrF(2). This analysis showed that the most remarkable difference between both molecules lies on the charge flux contribution to the asymmetric stretching mode, which is negligible in KrF(2) but important in XeF(2). (c) 2008 Elsevier B.V. All rights reserved.

Flexibilitetens frammarsch, en studie om den intermittenta anställningen

Flexible working conditions is used extensively in organizations today as a way to create flexibility for the employer. Recently we’ve been reading in the newspapers that this approach is a growing problem and the EU has warned Sweden twice that abuse of these forms of employment must be stopped. The Government has recently submitted a proposed rule change to reduce the possibility of stacking one temporary contract after another. Borlänge kommun makes themselves more flexible with the intermittent employments. This study aims to examine why infrequent employments, such as the intermittent employment is used and preferred by Borlänge kommun and how it’s perceived by affected employees in the organization. The questions related, besides why the intermittent employment is used by the organization and how its perceived by those involved, also includes the management of intermittent employment and how the organization is handling work contracts. The background information on the employment law implications gives the reader an insight into how the regulatory framework works surrounding the topic. The theory section highlights the main theories about flexibility and its different shapes and perspectives. For the study a qualitative approach is used. A case study with semi-structured interviews was performed. The respondents were employees involved in the staffing of intermittent employees and also members of the staff with an intermittent employment. The results show that the employment and contracts is correctly handled by labour law regulations. This study shows that Borlänge kommun uses intermittent employments extensively, with its 1 320 intermittently employees. If this is abuse, or not, is not clear from the result. The authors discuss, however, if that is the case. The intermittent employment is used mainly because of the great needs. This is because society is changing and the average age is increasing, both by those using the services and the employees. All respondents perceive the intermittent employment as most flexible for the employees. Respondents working in the staffing department say that they are not flexible enough. The intermittent employees’ working today does not cover the great need. Borlänge kommun think that the flexibility should benefit them more and is currently trying to become more flexible. The employees were generally satisfied with their work situation. Some tendencies of insecurity and uncertainty could be inferred from the intermittent employees answers. The author’s conclusions are that flexibility and the intermittent employment contracts mainly benefit the employer and the employees who actively choose this type of work, such as students. This kind of employment affects, however, the society and those who need a secure lifestyle. The necessary permanent contracts are becoming fewer and replaced by precarious and flexible employment conditions.

Electronically Querying for the Provenance of Entities

The provenance of entities, whether electronic data or physical artefacts, is crucial information in practically all domains, including science, business and art. The increased use of software in automating activities provides the opportunity to add greatly to the amount we can know about an entityâ??s history and the process by which it came to be as it is. However, it also presents difficulties: querying for the provenance of an entity could potentially return detailed information stretching back to the beginning of time, and most of it possibly irrelevant to the querier. In this paper, we define the concept of provenance query and describe techniques that allow us to perform scoped provenance queries.

Tecnicas de sensoriamento remoto e geoprocessamento aplicadas ao mapeamento geologico e geotecnico no municipio de Tres Cachoeiras, litoral norte do Rio Grande do Sul

As técnicas de sensoriarnento remoto e geoprocessamento são fundamentais para processamento e integração de dados de mapeamento geológico/geotécnico, principalmente estudos de gerenciamento e planejamento. A área estudada compreende o município de Três Cachoeiras. Litoral Norte do Rio Grande do Sul o qual inclui-se na "Reserva da Biosfera da Mata Atlântica". O município tem st: deparado com problemas de localização de sitios adequados à disposição final dos resíduos sólidos. bem como o assentamento de loteamentos residenciais e industriais, localização de jazidas de extração de material para construção, fontes de abastecimento de água e necessidade de criação de áreas de preservação ambiental. O objetivo deste trabalho foi produzir mapeamentos da área em questão, através da pesquisa geológico-geotécnica desenvolvida com emprego de imagens de satélite e fotografias aéreas, em que as informações foram cruzadas no SIG. Baseado nisto, investigaram-se os aspectos acima mencionados. a partir de uma contribuição geológico/geotécnica ao município, incluindo-se levantamento de campo, fotointerpretação, processamento e classificação de imagens do município de Três Cachoeiras, sendo os dados integrados num sistema de geoprocessamento. Utilizando-se cartas planialtimétricas, fotografias aéreas e imagem de satélite LANDSAT TM5. foram criados planos de informação como o limite da área estudada, a estrutura viária municipal, a delimitação de reservas ecológicas baseadas na legislação ambiental vigente e, por meio do modelo numérico do terreno, a carta de declividade. A fotointerpretação gerou planos de rede de drenagem, litológica. morfoestruturas e formações superficiais. Os dados de campo. sobrepostos às litológicas obtidas por fotointerpretação, produziram a carta litológica. No tratamento das imagem, foram gerados produtos com contraste, operações entre bandas, filtragens e análise de componentes principais, os quais contribuíram parira classificação da imagem e resultando nos planos de rochas/solos e cobertura/uso do solo (carta de uso atual do solo). O cruzamento destas informações permitiu a obtenção da carta de formações superficiais, lidrogeológica que, juntamente com as cartas litológica, declividades e uso atual do solo distribuíram os atributos do meio físico em planos elaborados por novos cruzamentos, que satisfazem o objetivo do estudo, sendo estes planos o produto final, ou seja, cartas de recomendação: a extração de materiais para construção civil; a implantação de obras de infraestrutura; a disposição de resíduos sólidos e loteamentos; geotécnica à agricultura; à implantação de áreas destinadas à preservação ambienta1 e recuperação.