Raman spectra of polymer electrolytes based on poly(ethylene glycol) dimethyl ether, lithium perchlorate, and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

Raman spectra of polymer electrolytes based on poly(ethylene glycol) dimethyl ether (PEGdME) with LiClO(4), PEGdME/LiClO(4), and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, PEGdME/[bmim]PF(6), are compared. Raman spectroscopy suggests stronger interactions in PEGdME/LiClO(4) than PEGdmE/[bmim]PF(6), thus corroborating previous results obtained by molecular dynamics simulations. Quantum Chemistry methods have been used to calculate vibrational frequencies and the equilibrium structure of segments of the polymer chain around the cation. A consistent picture has been obtained from Raman spectroscopy, density functional theory (DFT) calculations, and molecular dynamics simulations for these polymer electrolytes. (C) 2010 Elsevier B.V. All rights reserved.

The gas-phase alcoholysis of protonated homoleptic alkoxysilanes

Tetra-alkoxysilanes are common and useful reagents in sol-gel processes and understanding their reactivity is important in the design of new materials. The mechanism of gas-phase reactions that mimic alcoholyis of Si(OMe)(4) (usually known as TMOS) under acidic conditions have been studied by Fourier transform ion cyclotron resonance techniques and density functional calculations at the B3LYP/6-311+G(d,p) level. The proton affinity of TMOS has been estimated at 836.4 kJ mol(-1) and protonation of TMOS gives rise to an ionic species that is best represented as trimethoxysilyl cations associated with a methanol molecule. Protonated TMOS undergoes rapid and sequential substitution of the methoxy groups in the gas-phase upon reaction with alcohols. The calculated energy profile of the reaction indicates that the substitution reaction through an S(N)2 type mechanism may be more favorable than frontal attack at silicon. Furthermore, the sequential substitution reactions are promoted by a mechanism that involves proton shuttle from the most favorable protonation site to the oxygen of the departing group mediated by the neutral reagent molecule.

Studies on chemo- and diastereo-selectivity of the Diels-Alder reactions of sulfinyltoluquinones with cyclopentadiene

Sulfinyltoluquinones (2a-2c) were submitted to thermal or catalyzed [4+2] cycloaddition reactions with cyclopentadiene. For p-tolylsulfinyltoluquinones (2b) and (2c), almost complete C2-C3-chemo- and unlike-diastereoselectivity was achieved by catalysis with ZnBr(2), yielding adducts 6. Under thermal conditions, Diels-Alder reaction took place at the C5-C6 double bonds of quinones 2a-2c, generating mixtures of diastereoisomeric like- and unlike-adducts 4.

Co/Mg/Al hydrotalcite-type precursor, promoted with La and Ce, studied by XPS and applied to methane steam reforming reactions

Catalysts` precursor of Co/Mg/Al promoted with Ce and La were tested in the steam reforming of methane (SRM). The addition of promoters was made by anion-exchange. The oxides characterization was made by X-ray Photoelectron Spectroscopy (XPS) analysis that confirmed Co(2+) species in free form on surface and interacted with Mg and Al in the form of solid solution. In the SRM with high fed molar ratio of H(2)O:CH(4) = 4:1, the catalysts showed a great affinity with water and immediately deactivated by oxidation of the active sites. In the stoichiometric ratio of H(2)O:CH(4) = 2: 1 the catalysts were active and presented low carbon deposition during the time reaction tested. Also a test with low fed molar ratio H(2)O:CH(4) = 0.5:1 was carried out to evaluate the stability of the catalysts by CH(4) decomposition and all the catalysts were stable during 6 h of reaction. Promoted catalysts presented lower carbon deposition. (C) 2009 Elsevier B. V. All rights reserved.

Cobalt catalysts promoted with cerium and lanthanum applied to partial oxidation of methane reactions

Catalysts of Co/Mg/Al promoted with Ce and La were tested in the catalytic partial oxidation of methane (POM) reaction. The addition of promoters was made by anion-exchange. X-ray diffraction (XRD) confirmed the formation of hydrotalcite phase for precursors. The mixed oxides were characterized as a mixture of Co3O4, periclase (Co, Al)MgO and/or spinel structure (Mg, Co)Al2O4. In the catalytic POM reaction over the promoted catalysts, a reduction in the carbon formation rate was found. (c) 2008 Elsevier B.V. All rights reserved.

Effects of adding La and Ce to hydrotalcite-type Ni/Mg/Al catalyst precursors on ethanol steam reforming reactions

Catalyst precursors composed of Ni/Mg/Al oxides with added La and Ce were tested in ethanol steam reforming (ESR) reactions. La and Ce were added by anion-exchange. The oxides were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) analysis. The catalyst precursors consist of a mixture of oxides, with the nickel in the form of NiO strongly interacting with the support Mg/Al. The XPS analysis showed a lanthanum-support interaction, but no interaction of Ce species with the support. The reaction data obtained with the active catalysts showed that the addition of Ce and La resulted in better H(2) production at 550 degrees C. The CeNi catalyst provided the higher ethanol conversion, with lower acetaldehyde production, possibly clue to a favoring of water adsorption on the weakly interacting clusters of CeO(2) on the surface. (C) 2010 Elsevier B.V. All rights reserved.

Ethanol oxidation reactions using SnO(2)@Pt/C as an electrocatalyst

This paper presents a study on the ethanol oxidation reaction using SnO(2)@Pt/C core-shell structures as electrocatalysts. All the materials used, including Pt/C and PtSn/C E-tek, were 20% (w/w) metal on carbon. The formation of core-shell nanoparticles (SnO(2)@Pt/C) was measured by UV-vis spectrophotometry. X-ray diffraction measurements showed Pt (shell) diffraction patterns without influence from the SnO(2) core and without any shift in 2 theta values for Pt. The diameters of the core-shell particle structures, measured using high-resolution transmission electron microscopy images, were in the range of 3-16 nm. The electrochemical profile for SnO(2)@Pt/C in an acidic medium (H(2)SO(4) at a concentration of 0.5 mol L(-1)) was almost the same as the typical electrochemical behavior for Pt in an acidic medium. Furthermore, the onset potential for the ethanol oxidation reaction using SnO(2)@Pt/C was almost the same as that for PtSn/C E-tek (0.23 V versus the reversible hydrogen electrode). However, the mass current peak densities for ethanol oxidation were 50% higher on SnO(2)@Pt/C than on PtSn/C E-tek. In the polarization curve, the mass current density for ethanol oxidation was higher at all potentials for SnO(2)@Pt/C when compared to Pt/C and PtSn/C E-tek. At 0.5 V, the current mass density for ethanol oxidation on SnO(2)@Pt was 2.3 times of that for the same process on the commercial material. The electrocatalytic activity of SnO(2)@Pt/C for ethanol oxidation was associated with an increase in the electrochemically active surface area. However, an electronic effect should also be considered because the Pt shell changes its electronic structure in the presence of the foreign core. (C) 2010 Elsevier B.V. All rights reserved.

Methane conversion reactions on Ni catalysts promoted with Rh: Influence of support

Ni catalysts supported on gamma-Al(2)O(3) and Mg(Al)O were prepared with and without Rh as a promoter and tested in the reforming of methane in the presence of excess methane, simulating a model biogas. The effects of adding synthetic air on the methane conversion and the formation of carbon were assessed. The catalysts were characterized by X-ray spectroscopy (EDS), surface area (BET), X-ray diffraction (XRD), Temperature-programmed reduction (TPR), X-ray absorption near-edge structure (XANES) and XPD. The results showed that in catalysts without Rh, the Ni interacts strongly with the supports, showing high reduction temperatures in TPR tests. The addition of Rh increased the amount of reducible Ni and facilitated the reduction of the species interacting strongly with the support. In the catalytic tests, the samples promoted with Rh suffered higher carbon deposition. The in situ XPD suggested that on the support gamma-Al(2)O(3), the presence of Rh probably led to a segregation of Ni species with time on stream, leading to carbon deposition. On the support MgAlO, the presence of Rh improved the dispersion of Ni, by reducing the Ni(0) crystallite size, suggesting that in this case the carbon deposition was due to a favoring of CH(4) decomposition by Rh. (C) 2011 Elsevier B.V. All rights reserved.

On the interaction of bovine serum albumin with ionic surfactants: Temperature induced EPR changes of a maleimide nitroxide reflect local protein dynamics and probe solvent accessibility

The interaction of bovine serum albumin (BSA) with the ionic surfactants sodium dodecylsulfate (SDS, anionic), cetyltrimethylammonium chloride (CTAC, cationic) and N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS, zwitterionic) was studied by electron paramagnetic resonance (EPR) spectroscopy of spin label covalently bound to the single free thiol group of the protein. EPR spectra simulation allows to monitor the protein dynamics at the labeling site and to estimate the changes in standard Gibbs free energy, enthalpy and entropy for transferring the nitroxide side chain from the more motionally restricted to the less restricted component. Whereas SDS and CTAC showed similar increases in the dynamics of the protein backbone for all measured concentrations. HPS presented a smaller effect at concentrations above 1.5 mM. At 10 mM of surfactants and 0.15 mM BSA, the standard Gibbs free energy change was consistent with protein backbone conformations more expanded and exposed to the solvent as compared to the native protein, but with a less pronounced effect for HPS. In the presence of the surfactants, the enthalpy change, related to the energy required to dissociate the nitroxide side chain from the protein, was greater, suggesting a lower water activity. The nitroxide side chain also detected a higher viscosity environment in the vicinity of the paramagnetic probe induced by the addition of the surfactants. The results suggest that the surfactant-BSA interaction, at higher surfactant concentration, is affected by the affinities of the surfactant to its own micelles and micelle-like aggregates. Complementary DLS data suggests that the temperature induced changes monitored by the nitroxide probe reflects local changes in the vicinity of the single thiol group of Cys-34 BSA residue. (C) 2011 Elsevier B.V. All rights reserved.

Interaction of bovine serum albumin (BSA) with ionic surfactants evaluated by electron paramagnetic resonance (EPR) spectroscopy

EPR spectra of 5- and 16-doxyl stearic acid nitroxide probes (5-DSA and 16-DSA, respectively) bound to bovine serum albumin (BSA) revealed that in the presence of ionic surfactants, at least, two label populations coexist in equilibrium. The rotational correlation times (tau) indicated that component I displays a more restricted mobility state, associated to the spin labels bound to the protein; the less immobilized component 2 is due to label localization in the surfactant aggregates. For both probes, the increase of surfactant concentration leads to higher motional levels of component 1 followed by a simultaneous decrease of this fraction of nitroxides and its conversion into component 2. For 10 mM cethyltrimethylammonium chloride (CTAC), the nitroxides are 100% bound to the protein, whereas at 10mM N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) and sodium dodecyl sulfate (SDS) the fractions of bound nitroxides are reduced to 18% and 86%, respectively. No significant polarity changes were observed in the whole surfactant concentration range for component 1. Moreover, at higher surfactant concentration, component 2 exhibited a similar polarity as in the pure surfactant micelles. For 16-DSA the surfactant effect is different: at 10mM of HPS and CTAC the fractions of bound nitroxides are 76% and 49%, respectively, while at 10 mM SDS they are present exclusively in a micellar environment, consistent with 100% of component 2. Overall, both SDS and HPS are able to effectively displace the nitroxide probes from the protein binding sites. while CTAC seems to affect the nitroxide binding to a significantly smaller extent. (C) 2008 Elsevier B.V. All rights reserved.

Speak Good English Movement in Singapore : Reactions in Social and Traditional Media

The first Speak Good English Movement, SGEM, took place in 2000, and has been organized annually ever since. Speaking a “standard” form of English is considered to bring increased personal power. However, the SGEM wants the Singaporeans to use “standard” English in their private life as well. A decade after the beginning of the campaign, a Speak Good Singlish Movement was started. Based on studies of language and identity, it is understandable why some Singaporeans might feel the SGEM threatens their identity. However, the reactions towards the campaign are mainly positive. For the purposes of this analysis, Twitter messages, Facebook pages, and newspaper articles from The Straits Times were collected. The SGEM has hailed both direct and indirect praise and criticism in both social and traditional media: Five newspaper articles praise the campaign while five criticize it; the results are nine and seven respectively for social media. This thesis looks at reactions towards the SGEM in both social and traditional media, analyzes how these reactions might relate to the ideas of the power of language, its variety and the relation of language and identity.

Reactions of Persons with Dementia to Caregivers Singing in Morning Care Situations

Music therapeutic caregiving', when caregivers sing for or together with persons with severe dementia during care situations, has been suggested as a way to reduce problematic behaviors in dementia care. The present study implemented this technique as an intervention in dementia care. Six caregivers participated in group interviews about their experiences of morning care situations without and with'Music therapeutic caregiving'. Through a qualitative content analysis two themes emerged.'Being in a different reality' was based on'usual' morning care situations. The caregivers' experienced the persons with dementia as absent-minded; communication and cooperation were difficult. The second theme,'Being present', was based on morning care situations with the intervention. The caregivers described communication as enhanced; the persons with dementia expressed themselves more appropriately, making cooperation possible. The results indicate that'Music therapeutic caregiving' might lead to a more positive experience of the person with dementia and seems to increase receptivity to caregiving.  

Crown ethers : applications in inorganic synthesis

The ability of macroheterocyclic compounds to complex with ionic species has led to the synthesis and investigation of many multidentate macroheterocyclic species. The most stable complexes are formed between macrocyclic polyetheral ligands (crown ethers) with alkali or alkaline earth metal iona. There is an excellent correlation of the stability of these complexes with the size of the cation and the site of the cavity in the macrocyclic ligand. Additional factors, such as the basicity of the ligand and the solvating ability of the solvent, also play important roles in the stabilization of the complex. The stability of such complexes has been advantageously used to increase anionic reactivity and has been successfully applied to several organic fluorinations, oxidations, and similar reactions. The use of macrocyclic ligands in inorganic syntheses of otherwise difficult to obtain fluoro compounds has not been reported. O-carborane and m-carborane, C2BlOHl2, are icosahedral cage systems derived from Bl2H122- by replacement of BH with the isoelectronic CH group. These stable molecules exhibit electron-deficient bonding which can best be explained by delocalization of electrons. This delocalization gives rise to stability similar to that found in aromatic hydrocarbons. Crown ether activated potassium fluoride has been successfully employed in the conversion of alkyl, acyl and aryl halides to their respective fluorides. Analogously halide substituted carboranes were prepared, but their fluoro-derivatives were not obtained. The application of crown ethers in the synthesis of transition metal complexes is relatively unexplored. The usual synthesis of fluoro-derivative transition metal complexes involves highly reactive and toxic fluorinating agents such as antimony trifluoride, antimony penta fluoride. bromine trifluoride and hydrogen fluoride, An attempted preparation of the hexafluoroosmate (IV) ion via a crown activated, or naked fluoride~was unsuccessful. Potassium hexafluoroosmate (IV), K208F6. was eventually prepared using bromine trifluoride as a fluorinating and oxidizing agent .