Liquid-Liquid Flow in a Capillary Microreactor: Hydrodynamic Flow Patterns and Extraction Performance

The capillary micro reactor, with four stable operating flow patterns and a throughput range from grams per hour to kilograms per hour, presents an attractive alternative to chip-based and microstructured reactors for laboratory- and pilot-scale applications. In this article, results for the extraction of 2-butanol from toluene under different flow patterns in a water/toluene flow in long capillary microreactors are presented. The effects of the capillary length (0.4-2.2 m), flow rate (0.1-12 mL/min), and aqueous-to-organic volumetric flow ratio (0.25-9) on the slug, bubbly, parallel, and annular flow hydrodynamics were investigated. Weber-number-dependent flow maps were composed for capillary lengths of 0.4 and 2 m that were used to interpret the flow pattern formation in terms of surface tension and inertia forces. When the capillary length was decreased from 2 to 0.4 m, a transition from annular to parallel flow was observed. The capillary length had little influence on slug and bubbly flows. The flow patterns were evaluated in terms of stability, surface-to-volume ratio, throughput, and extraction efficiency. Slug and bubbly flow operations yielded 100% thermodynamic extraction efficiency, and increasing the aqueous-to-organic volumetric ratio to 9 allowed for 99% 2-butanol extraction. The parallel and annular flow operating windows were limited by the capillary length, thus yielding maximum 2-butanol extractions of 30% and 47% for parallel and annular flows, respectively.

Preferential CO oxidation over a copper-cerium oxide catalyst in a microchannel reactor

The activity of a 5-wt% Cu/CeO2-x catalyst during preferential CO oxidation in hydrogen-rich gas mixtures was studied in a microchannel reactor. The CO concentration dropped from 1 vol.% to 10 ppm at a selectivity of 60%, at a temperature of 190 degrees C, and a weight hour space velocity (WHSV) of 55,000 cm(3) g(-1) h(-1). Both the CO concentration and the temperature increased when the WHSV was increased from 50,000 to 500,000 cm(3) g(-1) h(-1). An increase of the O-2 concentration from a 1.2 to 3 fold excess reduced the CO concentration to 10 ppm in a broad temperature interval of 50 degrees C at WHSVs up to 275,000 cm(3) g(-1) h(-1). The preferential CO oxidation could be carried out at higher flow rates and at higher selectivities in the microchannel reactor compared to a fixed-bed flow reactor. (C) 2008 Elsevier B.V. All rights reserved.

The POINT-AGAPE survey - I. The variable stars in M31

For the purposes of identifying microlensing events, the POINT-AGAPE collaboration has been monitoring the Andromeda galaxy (M31) for three seasons (1999-2001) with the Wide Field Camera on the Isaac Newton Telescope. In each season, data are taken for one hour per night for roughly 60 nights during the six months that M31 is visible. The two 33 x 33 arcmin(2) fields of view straddle the central bulge, northwards and southwards. We have calculated the locations, periods and brightness of 35 414 variable stars in M31 as a by-product of the microlensing search. The variables are classified according to their period and brightness. Rough correspondences with classical types of variable star (such as Population I and II Cepheids, Miras and semiregular long-period variables) are established. The spatial distribution of Population I Cepheids is clearly associated with the spiral arms, while the central concentration of the Miras and long-period variables varies noticeably, the brighter and the shorter period Miras being much more centrally concentrated.

VLT FORS spectra of blue supergiants in the Local Group galaxy NGC 6822

Half hour exposures using the ESO VLT/FORS1 combination at Paranal in Chile have allowed us to obtain spectra for three B supergiants in the dwarf irregular galaxy NGC 6822. The spectra have been analysed using non-LTE techniques and temperatures, gravities, helium content and abundances have been obtained. Overall the metallicity of NGC 6822 is found to lie between that of the LMC and of the SMC, in agreement with previous observations of H II regions and in contrast to the earlier findings of Massey et al. (1995). The analysis of H-alpha yields estimates of the mass-loss rates and wind momenta. These results demonstrate that significantly longer exposures with the same instruments will allow us to perform quantitative spectroscopy of blue supergiants in galaxies far beyond the Local Group.

A focused ultrasoft X-ray microbeam for targeting cells individually with submicrometer accuracy

The application of microbeams is providing new insights into the actions of radiation at the cell and tissue levels. So far, this has been achieved exclusively through the use of collimated charged particles. One alternative is to use ultrasoft X rays, focused by X-ray diffractive optics. We have developed a unique facility that uses 0.2-0.8-mm-diameter zone plates to focus ultrasoft X rays to a beam of less than 1 mum diameter. The zone plate images characteristic K-shell X rays of carbon or aluminum, generated by focusing a beam of 5-10 keV electrons onto the appropriate target. By reflecting the X rays off a grazing-incidence mirror, the contaminating bremsstrahlung radiation is reduced to 2%. The focused X rays are then aimed at selected subcellular targets using rapid automated cell-finding and alignment procedures; up to 3000 cells per hour can be irradiated individually using this arrangement. (C) 2001 by Radiation Research Society.

Conundrums in Conservation: Complexity in Control

The departure point for this investigation is to highlight the centrality of regulation theory as a praxis in planning enforcement. The value of the conceptual framework is demonstrated by application in the problematic arena of conservation regulatory compliance, where there is currently a dearth of investigation. It is evidenced that this thematic approach provides a lens to scrutinise problematic areas of control and provides a deeper understanding of the difficulties faced by planning enforcement operational practice generally and heritage regimes specifically. The utility of the proposed mechanism is that it remedies the current well documented pitfalls of disjointed, piecemeal strategies by providing a framework for robust, coherent decision making not only in planning but in the wider regulatory arena.

Gentamicin-loaded nanoparticles show improved antimicrobial effects towards Pseudomonas aeruginosa infection

Gentamicin is an aminoglycoside antibiotic commonly used for treating Pseudomonas infections, but its use is limited by a relatively short half-life. In this investigation, developed a controlled-release gentamicin formulation using poly(lactide-co-glycolide) (PLGA) nanoparticles. We demonstrate that entrapment of the hydrophilic drug into a hydrophobic PLGA polymer can be improved by increasing the pH of the formulation, reducing the hydrophilicity of the drug and thus enhancing entrapment, achieving levels of up to 22.4 µg/mg PLGA. Under standard incubation conditions, these particles exhibited controlled release of gentamicin for up to 16 days. These particles were tested against both planktonic and biofilm cultures of P. aeruginosa PA01 in vitro, as well as in a 96-hour peritoneal murine infection model. In this model, the particles elicited significantly improved antimicrobial effects as determined by lower plasma and peritoneal lavage colony-forming units and corresponding reductions of the surrogate inflammatory indicators interleukin-6 and myeloperoxidase compared to free drug administration by 96 hours. These data highlight that the controlled release of gentamicin may be applicable for treating Pseudomonas infections.

A transiting companion to the eclipsing binary KIC002856960

We present an early result from an automated search of Kepler eclipsing binary systems for circumbinary companions. An intriguing tertiary signal has been discovered in the short period eclipsing binary KIC002856960. This third body leads to transit-like features in the light curve occurring every 204.2 days, while the two other components of the system display eclipses on a 6.2 hour period. The variations due to the tertiary body last for a duration of \sim1.26 days, or 4.9 binary orbital periods. During each crossing of the binary orbit with the tertiary body, multiple individual transits are observed as the close binary stars repeatedly move in and out of alignment with the tertiary object. We are at this stage unable to distinguish between a planetary companion to a close eclipsing binary, or a hierarchical triply eclipsing system of three stars. Both possibilities are explored, and the light curves presented.

Rod photoreceptor loss in Rho(-/-) mice reduces retinal hypoxia and hypoxia-regulated gene expression

PURPOSE. This study was conducted to evaluate whether regions of the retinal neuropile become hypoxic during periods of high oxygen consumption and whether depletion of the outer retina reduces hypoxia and related changes in gene expression.

METHODS. Retinas from rhodopsin knockout (Rho(-/-)) mice were evaluated along with those of wild-type (WT) control animals. Retinas were also examined at the end of 12-hour dark or light periods, and a separate group was treated with L-cis-diltiazem at the beginning of a 12-hour dark period. Hypoxia was assessed by deposition of hypoxyprobe (HP) and HP-protein adducts were localized by immunohistochemistry and quantified using ELISA. Also, hypoxia-regulated gene expression and transcriptional activity were assessed alongside vascular density.

RESULTS. Hypoxia was observed in the inner nuclear and ganglion cell layers in WT retina and was significantly reduced in Rho (-/-) mice (P < 0.05). Retinal hypoxia was significantly increased during dark adaptation in WT mice (P < 0.05), whereas no change was observed in Rho(-/-) or with L-cis-diltiazem-treated WT mice. Hypoxia-inducible factor (HIF)-1 alpha DNA-binding and VEGF mRNA expression in Rho(-/-) retina was significantly reduced in unison with outer retinal depletion (P < 0.05). Retina from the Rho(-/-) mice displayed an extensive intraretinal vascular network after 6 months, although there was evidence that capillary density was depleted in comparison with that in WT retinas.

CONCLUSIONS. Relative hypoxia occurs in the inner retina especially during dark adaptation. Photoreceptor loss reduces retinal oxygen usage and hypoxia which corresponds with attenuation of the retinal microvasculature. These studies suggest that in normal physiological conditions and diurnal cycles the adult retina exists in a state of borderline hypoxia, making this tissue particularly susceptible to even subtle reductions in perfusion.

The effect of lifestyle changes on results of 24-h ambulatory oesophageal pH monitoring

Twenty-four-hour pH monitoring is the 'gold standard' investigation of gastro-oesophageal reflux disease. It has been suggested that results may be influenced by lifestyle alteration during the study. The aim of this study was to determine the influence of lifestyle alteration and anxiety on outcome in pH monitoring.

The Use of Electrospray Mass Spectrometry to Determine Speciation in a Dynamic Combinatorial Library for Anion Recognition

The composition of a dynamic mixture of similar 2,2'-bipyridine complexes of iron(II) bearing either an amide (5-benzylamido-2,2'-bipyridine and 5-(2-methoxyethane)amido-2,2'-bipyridine) or an ester (2,2'-bipyridine-5-carboxylic acid benzylester and 2,2'-bipyridine-5-carboxylic acid 2-methoxyethane ester) side chain have been evaluated by electrospray mass spectroscopy in acetonitrile. The time taken for the complexes to come to equilibrium appears to be dependent on the counteranion, with chloride causing a rapid redistribution of two preformed heteroleptic complexes (of the order of 1 hour), whereas the time it takes in the presence of tetrafluoroborate salts is in excess of 24^^h. Similarly the final distribution of products is dependent on the anion present, with the presence of chloride, and to a lesser extent bromide, preferring three amide-functionalized ligands, and a slight preference for an appended benzyl over a methoxyethyl group. Furthermore, for the first time, this study shows that the distribution of a dynamic library of metal complexes monitored by ESI-MS can adapt following the introduction of a different anion, in this case tetrabutylammonium chloride to give the most favoured heteroleptic complex despite the increasing ionic strength of the solution. 

A biofuel strategy for Ireland with an emphasis on production of biomethane and minimization of land-take

Increasing energy consumption has exerted great pressure on natural resources; this has led to a move towards sustainable energy resources to improve security of supply and to reduce greenhouse gas emissions. However, the rush to the cure may have been made in haste. Biofuels in particular, have a bad press both in terms of competition with good agricultural land for food, and also in terms of the associated energy balance with the whole life cycle analysis of the biofuel system. The emphasis is now very much on sustainable biofuel production; biofuels from wastes and lignocellulosic material are now seen as good sustainable biofuels that affect significantly better greenhouse gas balances as compared with first generation biofuels. Ireland has a significant resource of organic waste that could be a potential source of energy through anaerobic digestion. Ireland has 8% of the cattle population of the EU with less than 1% of the human population; as a result 91% of agricultural land in Ireland is under grass. Residues such as slurries and slaughter waste together with energy crops such as grass have an excellent potential to produce biogas that may be upgraded to biomethane. This biomethane may be used as a natural gas substitute; bio-compressed natural gas may then be an avenue for a biofuel strategy. It is estimated that a maximum potential of 33% of natural gas may be substituted by 2020 with a practical obtainable level of 7.5% estimated. Together with biodiesel from residues the practical obtainable level of this strategy may effect greater than a 5% substitution by energy of transport. The residues considered in this strategy to produce biofuel (excluding grass) have the potential to save 93,000 ha of agricultural land (23% of Irish arable land) when compared to a rapeseed biodiesel strategy. © 2009 Elsevier Ltd. All rights reserved.

Structure of the methanol synthesis catalyst determined by in situ HERFD XAS and EXAFS

A Cu/ZnO/Al2O3 commercial catalyst for methanol synthesis from syngas was investigated under operational conditions. HERFD XAS and EXAFS data were recorded under different reaction gas mixtures, temperatures, and pressures. Activation of the catalyst precursor occurred via a Cu+ intermediate. The active catalyst predominantly consists of metallic Cu and ZnO. Methanol production only starts when all accessible Cu is reduced. The structure of the active catalyst did not change with temperature or pressure even though the methanol yield changed strongly. Formation of a carbon-containing layer on top of the catalyst surface was detected by TPD, which was correlated with a several-hour induction period in the methanol production after the catalyst reduction.

Multiplex Detection of Plant Pathogens Using a Microsphere Immunoassay Technology

Plant pathogens are a serious problem for seed export, plant disease control and plant quarantine. Rapid and accurate screening tests are urgently required to protect and prevent plant diseases spreading worldwide. A novel multiplex detection method was developed based on microsphere immunoassays to simultaneously detect four important plant pathogens: a fruit blotch bacterium Acidovorax avenae subsp. citrulli (Aac), chilli vein-banding mottle virus (CVbMV, potyvirus), watermelon silver mottle virus (WSMoV, tospovirus serogroup IV) and melon yellow spot virus (MYSV, tospovirus). An antibody for each plant pathogen was linked on a fluorescence-coded magnetic microsphere set which was used to capture corresponding pathogen. The presence of pathogens was detected by R-phycoerythrin (RPE)-labeled antibodies specific to the pathogens. The assay conditions were optimized by identifying appropriate antibody pairs, blocking buffer, concentration of RPE-labeled antibodies and assay time. Once conditions were optimized, the assay was able to detect all four plant pathogens precisely and accurately with substantially higher sensitivity than enzyme-linked immunosorbent assay (ELISA) when spiked in buffer and in healthy watermelon leaf extract. The assay time of the microsphere immunoassay (1 hour) was much shorter than that of ELISA (4 hours). This system was also shown to be capable of detecting the pathogens in naturally infected plant samples and is a major advancement in plant pathogen detection. © 2013 Charlermroj et al.

Growth and adrenal suppression in asthmatic children treated with high-dose fluticasone propionate

Background: Fluticasone propionate was introduced in 1993 in the UK as a potentially safer inhaled corticosteroid than those already in use. The efficacy and safety of fluticasone has been established at recommended doses of 200 µg/day, but not at the higher doses that are often used.

Methods: Growth retardation was observed in six severely asthmatic children after introduction of high-dose fluticasone propionate treatment (dry powder). Assessment of cortisol response was by insulin-induced hypoglycaemia in three cases, by short tetracosactrin test in two, and by low-dose tetracosactrin and 24-hour urinary cortisol/creatinine ratio in one.

Findings: Six children with growth retardation noted after treatment with high-dose fluticasone propionate were found to have adrenal suppression. In one case the growth rate and cortisol response returned to normal 9 months after the fluticasone dose was reduced to 500 µg/day.

Interpretation: When high doses of fluticasone propionate are used, growth may be retarded and adrenal suppression may occur.