Colloidal microgel in removal of water from biodiesel

A series of poly(N-isopropylacrylamide) [pNIPAM]-based homo-polymer and co-polymer microgel particles were prepared by surfactant-free emulsion polymerisation. The co-monomers were acrylic acid. 4-vinylpyridine. butyl acrylate, 4-vinylbiphenyl and vinyl laurate. Co-monomers were added at a concentration of 10% (w/w) relative to the base monomer pNIPAM for the preparation of each co-polymer microgel. The co-monomers chosen vary by their organic chain length, polarity and pH sensitivity, as these should influence how the particles behave in aqueous and non-aqueous solvents. The effect of adding different types of co-monomer into the microgel structure was investigated with respect to their dispersibility in different solvents. These microgel particles have shown useful application in the removal of water from biodiesel prepared from rape seed. Karl Fischer experiments showed that microgel particles can be used to reduce the water content in biodiesel to an acceptable level for incorporation into internal combustion engines. (C) 2008 Elsevier B.V. All rights reserved.

Spatial Variability of Durum Wheat Yield as Related to Soil Parameters in an Organic Field

The yield in organic farming is generally much lower than its potential, which is due to its specificity. The objective of the present study was to quantify the yield spatial variation of wheat and relate it to soil parameters in an organic farm located in the north of the Negev Desert. Soil samples were gathered in a triangular grid at three time intervals. Yields were measured at 73 georeferenced points before the actual harvest. Several thematic maps of soil and yield parameters were produced using geographic information system and geostatistical methods. The strongest spatial correlation was found in the weight of 1000 grains and the weakest was in carbon flow. Temporal relationships were found between soil nitrate concentration, soil water content, and leaf area index. Wheat yield varied from 1.11 to 2.84 Mg ha(-1) and this remarkable variation indicates that the spatial analysis of soil and yield parameters is significant in organic agriculture.

A polysaccharide extracted from sphagnum moss as antifungal agent in archaeological conservation

On the basis of the well-known preservative properties of Sphagnum moss, a potential opportunity to use moss polysaccharides (Sphagnan) in art conservation was tested. Polysaccharides were extracted from the moss (S. palustre spp.) in the amount of 4.1% of the Sphagnum plant dry weight. All lignocelluloses were removed from this extract as a result of the treatment of the moss cellulose with sodium chlorite. The extracted polysaccharide possessed a strong acidic reaction (pH 2.8) and was soluble in water and organic solvents. The extract was tested on laboratory bacterial cultures by the disk-diffusion method. The antibacterial effect was demonstrated for E. coli and P. aeruginosa (both gram-negative) while Staphylococcus aurelus (gram-positive) was shown to be insensitive to Sphagnum polysaccharides. The antifungal effect of Sphagnum extract was tested by the disk-diffusion method on the spores of seventeen fungal species. These fungi were isolated from ethnographic museum objects and from archaeological objects excavated in the Arctic. Twelve of these isolates appeared susceptible to the extract. The inhibiting effect of the extract was also tested by the modified broth-dilution method on the most typical isolate (Aspergillus spp.). In this experiment, in one ml of the nutritious broth, 40µl of 3% solution of polysaccharides in water killed 10,000 fungal spores in 6 hours. The inhibiting effect was not connected to the acidity or osmotic effect of Sphagnum polysaccharides. As an example of the application of Sphagnum polysaccharides in art conservation, they were added as preservative agents to conservation waxes. After three weeks of exposure of microcrystalline wax to test fungi (Aspergillus spp.), 44% of wax was consumed. When, however, ~ 0.1% (w/w) of Sphagnum extract was mixed with wax, the weight loss of wax was only 4% in the same time interval. On the basis of this study it was concluded that Sphagnum moss and Sphagnum products can be recommended for use in art conservation as antifungal agents.

Heterogeneously catalysed selective hydrogenation reactions in ionic liquids

The selective hydrogenation of , unsaturated aldehydes has been performed in a range of room temperature ionic liquids. The reaction data reported show that it is possible to enhance the selectivity of supported palladium catalysts for the reduction of the conjugated CC bond by using ionic liquids as solvents compared with conventional molecular organic solvents. The catalyst system is easily recycled without the need to isolate or filter the catalyst and may be used without further treatment.

The use of Raman microscopy to determine and localize vitamin E in biological samples

Alpha-tocopherol (aT), the predominant form of vitamin E in mammals, is thought to prevent oxidation of polyunsaturated fatty acids. In the lung, aT is perceived to be accumulated in alveolar type II cells and secreted together with surfactant into the epithelial lining fluid. Conventionally, determination of aT and related compounds requires extraction with organic solvents. This study describes a new method to determine and image the distribution of aT and related compounds within cells and tissue sections using the light-scattering technique of Raman microscopy to enable high spatial as well as spectral resolution. This study compared the nondestructive analysis by Raman microscopy of vitamin E, in particular aT, in biological samples with data obtained using conventional HPLC analysis. Raman spectra were acquired at spatial resolutions of 2-0.8 microm. Multivariate analysis techniques were used for analyses and construction of corresponding maps showing the distribution of aT, alpha-tocopherol quinone (aTQ), and other constituents (hemes, proteins, DNA, and surfactant lipids). A combination of images enabled identification of colocalized constituents (heme/aTQ and aT/surfactant lipids). Our data demonstrate the ability of Raman microscopy to discriminate between different tocopherols and oxidation products in biological specimens without sample destruction. By enabling the visualization of lipid-protein interactions, Raman microscopy offers a novel method of investigating biological characterization of lipid-soluble compounds, including those that may be embedded in biological membranes such as aT.

Behavior of the heterogeneous electron-transfer rate constants of arenes and substituted anthracenes in room-temperature ionic liquids

We report the anodic oxidation of several arenes and anthracenes within room-temperature ionic liquids (RTILs). In particular, the heterogeneous electron-transfer rates (k(0)) for substituted anthracenes and arenes are also investigated in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(2)mim][NTf2]) and found not to obey the outer-sphere Marcus-type behavior of these compounds in contrast to the behavior in traditional organic solvents,in particular the predictions for k(0) with molecular size and solvent static dielectric constant. To obtain the electron-transfer rate for 9-phenylanthracene, the dimerization and heterogeneous electron-transfer kinetics of its electrogenerated radical cations is studied in [C(2)mim][NTf2] and eight other RTILs and are both found to be largely independent of the solution viscosity.

Utilisation of ionic liquid solvents for the synthesis of Lily-of-the-Valley fragrance {beta-Lilial (R); 3-(4-t-butylphenyl)-2-methylpropanal}

The Heck arylation of 2-methylprop-2-en- I -ol in ionic liquids and organic solvents is reported using a range of homogeneous and heterogeneous palladium catalysts. Higher activity is observed in the ionic liquid media compared with N-methyl pyrrolidinone and under solventless conditions. The ionic liquid-catalyst system may be recycled easily with little loss in activity, although significant palladium leaching from the heterogeneous catalyst was observed. In the case of Trans-bis(2,3-dihydro-3-methylbenzothiazole-2-ylidene)diiodopalladium (11) reported to be highly active for this transformation, significant induction petiods were observed indicating that nanoparticles may be responsible for the catalysis. Using the ionic liquid Heck reaction, a recyclable synthesis for the fragrance beta-Lilial((R)) has been developed. (c) 2004 Elsevier B.V. All rights reserved.

Electroreduction of oxygen in a series of room temperature ionic liquids composed of group 15-centered cations and anions

The electrochemical reduction of oxygen is reported in four room temperature ionic liquids (RTILs) based on quaternary alkyl -onium cations and heavily fluorinated anions in which the central atom is either nitrogen or phosphorus. Data were collected using cyclic voltammetry and potential step chronoamperometry at gold, platinum, and glassy carbon disk electrodes of micrometer dimension under water-free conditions at a controlled temperature. Analysis via fitting, to appropriate theoretical equations was then carried out to obtain kinetic and thermodynamic information pertaining to the electrochemical processes observed. In the quaternary ammonium electrolytes, reduction of oxygen was found to occur reversibly to give stable superoxide, in an analogous manner to that seen in conventional aprotic solvents such as dimethyl sufoxide and acetonitrile. The most significant difference is in the relative rate of diffusion; the diffusion coefficients of oxygen in the RTILs are an order of magnitude lower than in common organic solvents, and for superoxide these values are reduced by a further factor of 10. In the quaternary phosphonium ionic liquids, however, more complex voltammetry is observed, akin to that expected for the reduction of oxygen in acidified organic media. This is shown to be consistent with the occurrence of a proton abstraction reaction between the electrogenerated superoxide and quaternary alkyl phosphonium cations following the initial electron transfer.

Phase transition and decomposition temperatures, heat capacities and viscosities of pyridinium ionic liquids

Ionic liquids are organic salts with low melting points. Many of these compounds are liquid at room temperature in their pure state. Since they have negligible vapor pressure and would not contribute to air pollution, they are being intensively investigated for a variety of applications, including as solvents for reactions and separations, as non-volatile electrolytes, and as heat transfer fluids. We present melting temperatures, glass transition temperatures, decomposition temperatures, heat capacities, and viscosities for a large series of pyridinium-based ionic liquids. For comparison, we include data for several imidazolium and quaternary ammonium salts. Many of the compounds do not crystallize, but form glasses at temperatures between 188 K and 223 K. The thermal stability is largely determined by the coordinating ability of the anion, with ionic liquids made with the least coordinating anions, like bis(trifluoromethylsulfonyl)imide, having the best thermal stability. In particular, dimethylaminopyridinium bis(trifluoromethylsulfonyl)imide salts have some of the best thermal stabilities of any ionic liquid compounds investigated to date. Heat capacities increase approximately linearly with increasing molar mass, which corresponds with increasing numbers of translational, vibrational, and rotational modes. Viscosities generally increase with increasing number and length of alkyl substituents on the cation, with the pyridinium salts typically being slightly more viscous than the equivalent imidazolium compounds. (c) 2005 Elsevier Ltd. All rights reserved.

Clean preparation of nanoparticulate metals in porous supports: a supercritical route

Here we present the synthesis of nanometre sized silver particles which have been trapped within porous substrates; poly( styrene-divinylbenzene) beads and silica aerogels. This is the first time that supercritical carbon dioxide has been used to impregnate such porous materials with silver coordination complexes. In this paper we demonstrate that control over the resultant nanoparticles with respect to size, loading and distribution in the support material has been achieved by simple choice of the precursor complex. The solubility of the precursor complexes in the supercritical solvent is shown to be one of the key parameters in determining the size of the nanoparticles, their distribution and their homogeneity within the support matrix. Moreover, we demonstrate that the same methodology can be applied to two very different substrate materials. In the particular case of aerogels, conventional organic solvents could not be used to prepare nanoparticles because the surface tension of the solvent would lead to fracturing of the aerogel structure.

Electrochemistry of Sulfur and Polysulfides in Ionic Liquids

The electrochemistry of elemental sulfur (S-8) and the polysulfides Na2S4 and Na2S6 has been studied for the first time in nonchloroaluminate ionic liquids. The cyclic voltammetry of S-8 in the ionic liquids is different to the behavior reported in some organic solvents, with two reductions and one oxidation peak observed. Supported by in situ UV-vis spectro-electrochemical experiments, the main reduction products of S-8 in [C(4)mim][DCA] ([C(4)mim] = 1-butyl-3-methylimidazolium; DCA = dicyanamide) have been identified as s(6)(2-) and S-4(2-), and plausible pathways for the formation of these species are proposed. Dissociation and/or disproportionation of the polyanions S-6(2-) and S-4(2-) appears to be slow in the ionic liquid, with only small amounts of the blue radical species S3(center dot-) formed in the solutions at r.t., in contrast with that observed in most molecular solvents.

Banking in Crisis: The Rise and Fall of British Banking Stability, 1800 to the Present

Can the lessons of the past help us to prevent another banking collapse in the future? This is the first book to tell the story of the rise and fall of British banking stability in the past two centuries, and it sheds new light on why banking systems crash and the factors underpinning banking stability. John Turner shows that there were only two major banking crises in Britain during this time: the crisis of 1825–6 and the Great Crash of 2007–8. Although there were episodic bouts of instability in the interim, the banking system was crisis-free. Why was the British banking system stable for such a long time and why did the British banking system implode in 2008? In answering these questions, the book explores the long-run evolution of bank regulation, the role of the Bank of England, bank rescues and the need to hold shareholders to account.

Low pressure carbon dioxide solubility in pure electrolyte solvents for lithium-ion batteries as a function of temperature. Measurement and prediction

Experimental values for the carbon dioxide solubility in eight pure electrolyte solvents for lithium ion batteries – such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ?-butyrolactone (?BL), ethyl acetate (EA) and methyl propionate (MP) – are reported as a function of temperature from (283 to 353) K and atmospheric pressure. Based on experimental solubility data, the Henry’s law constant of the carbon dioxide in these solvents was then deduced and compared with reported values from the literature, as well as with those predicted by using COSMO-RS methodology within COSMOthermX software and those calculated by the Peng–Robinson equation of state implemented into Aspen plus. From this work, it appears that the CO2 solubility is higher in linear carbonates (such as DMC, EMC, DEC) than in cyclic ones (EC, PC, ?BL). Furthermore, the highest CO2 solubility was obtained in MP and EA solvents, which are comparable to the solubility values reported in classical ionicliquids. The precision and accuracy of the experimental values, considered as the per cent of the relative average absolute deviations of the Henry’s law constants from appropriate smoothing equations and from literature values, are close to (1% and 15%), respectively. From the variation of the Henry’s law constants with temperature, the partial molar thermodynamic functions of dissolution such as the standard Gibbs free energy, the enthalpy, and the entropy are calculated, as well as the mixing enthalpy of the solvent with CO2 in its hypothetical liquid state.

Comparing the influence of two different natural organic matter types on colloid deposition in saturated porous medium

Humic acid and protein are two major organic matter types encountered in natural and polluted environment, respectively. This study employed Triple Pulse Experiments (TPEs) to investigate and compare the influence of Suwannee River Humic Acid (SRHA) (model humic acid) and Bovine Serum Albumin (BSA) (model protein) on colloid deposition in a column packed with saturated iron oxide-coated quartz sand. Study results suggest that adsorbed SRHA may inhibit colloid deposition by occupying colloid sites on the porous medium. Conversely, BSA may promote colloid deposition by a 'filter ripening' mechanism. This study provides insight to understand the complex behavior of colloids in organic matter-presented aquifers and sand filters. © (2012) Trans Tech Publications, Switzerland.

One size fits all: stability of metabolic scaling under warming and ocean acidification in echinoderms

Responses by marine species to ocean acidification (OA) have recently been shown to be modulated by external factors including temperature, food supply and salinity. However the role of a fundamental biological parameter relevant to all organisms, that of body size, in governing responses to multiple stressors has been almost entirely overlooked. Recent consensus suggests allometric scaling of metabolism with body size differs between species, the commonly cited 'universal' mass scaling exponent (b) of A3/4 representing an average of exponents that naturally vary. One model, the Metabolic-Level Boundaries hypothesis, provides a testable prediction: that b will decrease within species under increasing temperature. However, no previous studies have examined how metabolic scaling may be directly affected by OA. We acclimated a wide body-mass range of three common NE Atlantic echinoderms (the sea star Asterias rubens, the brittlestars Ophiothrix fragilis and Amphiura filiformis) to two levels of pCO(2) and three temperatures, and metabolic rates were determined using closed-chamber respirometry. The results show that contrary to some models these echinoderm species possess a notable degree of stability in metabolic scaling under different abiotic conditions; the mass scaling exponent (b) varied in value between species, but not within species under different conditions. Additionally, we found no effect of OA on metabolic rates in any species. These data suggest responses to abiotic stressors are not modulated by body size in these species, as reflected in the stability of the metabolic scaling relationship. Such equivalence in response across ontogenetic size ranges has important implications for the stability of ecological food webs.