A kinetic study of the liquid-phase hydrogenation of citral on Au/TiO2 and Pt-Sn/TiO2 thin films in capillary microreactors

The kinetics of the liquid-phase hydrogenation of citral (3,7-dimethyl-2,6-octadienal) on Au/TiO2 and Pt-Sn/TiO2 thin films was studied in the temperature range 313-353 K and citral concentrations of 0.25-10.0 mol m(-3). The thin films were deposited onto the inner walls of silica capillaries with internal diameter of 250 mu m. First-order dependence on hydrogen pressure and near zero order dependence on citral concentration were observed for the initial rate of citral hydrogenation over the Pt-Sn/TiO2 and Au/TiO2 thin films. The Au/TiO2 catalyst prevents citronellal formation. The highest yield of unsaturated alcohols was obtained on the Pt-Sn/TiO2 film at a reaction temperature of 343 K, liquid residence time of 30 min and a citral conversion of 99%. (C) 2011 Elsevier B.V. All rights reserved.

Theoretical and experimental correlations of gas dissolution, diffusion, and thermodynamic properties in determination of gas permeability and selectivity in supported ionic liquid membranes

Supported ionic liquid membranes (SILMs) has the potential to be a new technological platform for gas/organic vapour separation because of the unique non-volatile nature and discriminating gas dissolution properties of room temperature ionic liquids (ILs). This work starts with an examination of gas dissolution and transport properties in bulk imidazulium cation based ionic liquids [C_nmim][NTf2] (n = 2.4, 6, 8.10) from simple gas H₂, N₂, to polar CO₂, and C₂H₆, leading to a further analysis of how gas dissolution and diffusion are influenced by molecular specific gas-SILMs interactions, reflected by differences in gas dissolution enthalpy and entropy. These effects were elucidated again during gas permeation studies by examining how changes in these properties and molecular specific interactions work together to cause deviations from conventional solution–diffusion theory and their impact on some remarkably contrasting gas perm-selectivity performance. The experimental perm-selectivity for all tested gases showed varied and contrasting deviation from the solution–diffusion, depending on specific gas-IL combinations. It transpires permeation for simpler non-polar gases (H₂, N₂) is diffusion controlled, but strong molecular specific gas-ILs interactions led to a different permeation and selectivity performance for C₂H₆ and CO₂. With exothermic dissolution enthalpy and large order disruptive entropy, C₂H₆ displayed the fastest permeation rate at increased gas phase pressure in spite of its smallest diffusivity among the tested gases. The C₂H₆ gas molecules “peg” on the side alkyl chain on the imidazulium cation at low concentration, and are well dispersed in the ionic liquids phase at high concentration. On the other hand strong CO₂-ILs affinity resulted in a more prolonged “residence time” for the gas molecule, typified by reversed CO₂/N₂ selectivity and slowest CO₂ transport despite CO₂ possess the highest solubility and comparable diffusivity in the ionic liquids. The unique transport and dissolution behaviour of CO₂ are further exploited by examining the residing state of CO₂ molecules in the ionic liquid phase, which leads to a hypothesis of a condensing and holding capacity of ILs towards CO₂, which provide an explanation to slower CO₂ transport through the SILMs. The pressure related exponential increase in permeations rate is also analysed which suggests a typical concentration dependent diffusion rate at high gas concentration under increased gas feed pressure. Finally the strong influence of discriminating and molecular specific gas-ILs interactions on gas perm-selectivity performance points to future specific design of ionic liquids for targeted gas separations.

School Neighborhood Disadvantage as a Predictor of Long-Term Sick Leave Among Teachers: Prospective Cohort Study

This ongoing prospective study examined characteristics of school neighborhood and neighborhood of residence as predictors of sick leave among school teachers. School neighborhood income data for 226 lower-level comprehensive schools in 10 towns in Finland were derived from Statistics Finland and were linked to register-based data on 3,063 teachers with no long-term sick leave at study entry. Outcome was medically certified (> 9 days) sick leave spells during a mean follow-up of 4.3 years from data collection in 2000-2001. A multilevel, cross-classified Poisson regression model, adjusted for age, type of teaching job, length and type of job contract, school size, baseline health status, and income level of the teacher's residential area, showed a rate ratio of 1.30 (95% confidence interval: 1.03, 1.63) for sick leave among female teachers working in schools located in low-income neighborhoods compared with those working in high-income neighborhoods. A low income level of the teacher's residential area was also independently associated with sick leave among female teachers (rate ratio = 1.50, 95% confidence interval: 1.18, 1.91). Exposure to both low-income school neighborhoods and low-income residential neighborhoods was associated with the greatest risk of sick leave (rate ratio = 1.71, 95% confidence interval: 1.27, 2.30). This study indicates that working and living in a socioeconomically disadvantaged neighborhood is associated with increased risk of sick leave among female teachers.

Hydrodynamic cavitation in micro channels with channel sizes of 100 and 750 micrometers

Decreasing the constriction size and residence time in hydrodynamic cavitation is predicted to give increased hot spot temperatures at bubble collapse and increased radical formation rate. Cavitation in a 100 x 100 mu m(2) rectangular micro channel and in a circular 750 mu m diameter milli channel has been investigated with computational fluid dynamics software and with imaging and radical production experiments. No radical production has been measured in the micro channel. This is probably because there is no spherically symmetrical collapse of the gas pockets in the channel which yield high hot spot temperatures. The potassium iodide oxidation yield in the presence of chlorohydrocarbons in the milli channel of up to 60 nM min(-1) is comparable to values reported on hydrodynamic cavitation in literature, but lower than values for ultrasonic cavitation. These small constrictions can create high apparent cavitation collapse frequencies.

Pre-Retirement Age Migration to Remote Rural Areas

Recent literature suggests that the increasingly blurred relationship between paid employment and retirement facilitates a retirement transition period, a life course stage, which may involve a change of residence. The role of such pre-retirement age mobility in the repopulation of rural areas has, however, received relatively little academic scrutiny. This paper draws upon findings from a two-year study conducted in three UK case study areas. It examines the extent of pre-retirement age (aged 50–64) migration into remote rural communities and the impacts this type of movement has upon economic activity, social and community engagement and service provision. It is argued that while this under-researched cohort offers opportunities to support the social and economic sustainability of rural communities (at least in the short and medium term), there are notable challenges which are likely to emerge as it ages in situ. The findings are particularly relevant given national trends on population ageing.

The removal of patients who live outside the practice boundary:a study of outside-area removals in Northern Ireland in 2001-2002

It has been suggested that there are significant overlaps between removals due to deregistration and removals arising because patients live outside the practice area. If this is true, it would mean that the current estimates of deregistration would need to be revised upwards. All outside-area removals for the calendar years 2001 and 2002 were reviewed and characterised by age, sex and Jarman score of the enumeration district of the patients' residence and distance from the practice. The average outside-area removal rate was just over one removal per practice per year. Removal rates were highest between the ages of 18 and 44 years; there were no significant differences between the sexes. Rates of removal increased exponentially with distance, although even at marked distances from the practice there were about 10 patients remaining on the list for each one removed. Residents in deprived areas were more likely to be removed, although because areas most distal to the practice tend to be affluent, overall there was a predominance of affluent patients among those who are removed. In Northern Ireland rates of outside-area removal are only slightly higher than those of deregistration. It is evident that GPs are exercising some discretion as to which of the outside-area patients they retain on their list. This has the potential to cause some misunderstanding and resentment among patients, as has been reported previously.

THE MARINE RADIOCARBON BOMB PULSE ACROSS THE TEMPERATE NORTH ATLANTIC: A COMPILATION OF Delta C-14 TIME HISTORIES FROM ARCTICA ISLANDICA GROWTH INCREMENTS

Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Delta C-14 excess from known-age annual increments of the long-lived bivalve mollusk Arctica islandica from 4 sites across the coastal North Atlantic (German Bight, North Sea; Tromso, north Norway; Siglufjordur, north Icelandic shelf; Grimsey, north Icelandic shelf) combined with published series from Georges Bank and Sable Bank (NW Atlantic) and the Oyster Ground (North Sea). The atmospheric bomb pulse is shown to be a step-function whose response in the marine environment is immediate but of smaller amplitude and which has a longer decay time as a result of the much larger marine carbon reservoir. Attenuation is determined by the regional hydrographic setting of the sites, vertical mixing, processes controlling the isotopic exchange of C-14 at the air-sea boundary, C-14 content of the freshwater flux, primary productivity, and the residence time of organic matter in the sediment mixed layer. The inventories form a sequence from high magnitude-early peak (German Bight) to low magnitude-late peak (Grimsey). All series show a rapid response to the increase in atmospheric Delta C-14 excess but a slow response to the subsequent decline resulting from the succession of rapid isotopic air-sea exchange followed by the more gradual isotopic equilibration in the mixed layer due to the variable marine carbon reservoir and incorporation of organic carbon from the sediment mixed layer. The data constitute calibration series for the use of the bomb pulse as a high-resolution dating tool in the marine environment and as a tracer of coastal ocean water masses.

Using temporal analysis of products and flux response technology to determine diffusion coefficients in catalytic monoliths

The importance of accurately measuring gas diffusivity in porous materials has led to a number of methods being developed. In this study the Temporal Analysis of Products (TAP) reactor and Flux Response Technology (FRT) have been used to examine the diffusivity in the washcoat supported on cordierite monoliths. Herein, the molecular diffusion of propane within four monoliths with differently prepared alumina/CeZrOx washcoats was investigated as a function of temperature. Moment-based analysis of the observed TAP responses led to the calculation of the apparent intermediate gas constant, Kp, that characterises adsorption into the mesoporous network and apparent time delay, tapp, that characterises residence time in the mesoporous network. Additionally, FRT has been successfully adapted as an extensive in situ perturbation technique in measuring intraphase diffusion coefficients in the washcoats of the same four monolith samples. The diffusion coefficients obtained by moment-based analysis of TAP responses are larger than the coefficients determined by zero length column (ZLC) analysis of flux response profiles with measured values of the same monolith samples between 20 and 100 °C ranging from 2–5×10^-9 m² s^-1 to 4–8×10^-10 m² s^-1, respectively. The TAP and FRT data, therefore, provide a range of the lower and upper limits of diffusivity, respectively. The reported activation energies and diffusivities clearly correlate with the difference in the washcoat structure of different monolith samples.

Methylation using dimethylcarbonate catalysed by ionic liquids under continuous flow conditions

The ionic liquid, tributylmethylammonium methylcarbonate, has been employed as a catalytic base for clean N-methylation of indole with dimethylcarbonate. The reaction conditions were optimised under microwave heating to give 100% conversion and 100% selectivity to N-methylindole, and subsequently transferred to a high temperature/high pressure (285 degrees C/150 bar) continuous flow process using a short (3 min) residence time and 2 mol% of the catalyst to efficiently methylate a variety of different amines, phenols, thiophenols and carboxylic acid substrates. The extremely short residence times, versatility, and high selectivity have significant implications for the synthesis of a wide range of pharmaceutical intermediates, as high product throughputs can be obtained via this scalable continuous flow protocol. It has also been shown that the ionic liquid can be generated in situ from tributylamine, which has the net effect of transforming an ineffective stoichiometric base into a highly efficient catalyst for this broad class of reactions.

Methane to higher hydrocarbons via halogenation

Activation of methane with a halogen followed by the metathesis of methyl halide is a novel route from methane to higher hydrocarbons or oxygenates. Thermodynamic analysis revealed that bromine is the most suitable halogen for this goal. Analysis of the published data on the reaction kinetics in a CSTR enabled us to judge on the effects of temperature, reactor residence time and the feed concentrations of bromine and methane to the conversion of methane and the selectivity towards mono or dibromomethane. The analysis indicated that high dibromomethane selectivity is attainable (over 90%) accompanied by high methane conversions. The metathesis of dibromomethane can provide an alternative route to the conversion of methane (natural gas) economically with smaller installations than the current syn-gas route. (c) 2005 Elsevier B.V. All rights reserved.

Dioxouranium(VI) extraction in microchannels using ionic liquids

The extraction of uranium(VI) from aqueous nitric acid solutions by tributylphosphate {TBP; 30%(v/v)} dissolved in the ionic liquid 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide was investigated. The experiments were performed in a Teflon microchannel of 0.5 mm internal diameter, while the dioxouranium(VI) concentrations in the aqueous and the ionic liquid phases were determined by UV-Vis spectroscopy. The effects of initial nitric acid concentration (0.01-3 M), residence time, and phase flow rate ratio were studied. It was found that, with increasing nitric acid concentration, the percentage of dioxouranium(VI) extracted decreased and then increased again, while the extraction efficiency followed a slightly different trend. Overall mass transfer coefficients varied between 0.049 s and 0.312 s . © 2012 Elsevier B.V. All rights reserved.

Studies to Reduce Unnecessary Medication Use in Frail Older Adults:A Systematic Review

BACKGROUND: Overuse of unnecessary medications in frail older adults with limited life expectancy remains an understudied challenge. OBJECTIVE: To identify intervention studies that reduced use of unnecessary medications in frail older adults. A secondary goal was to identify and review studies focusing on patients approaching end of life. We examined criteria for identifying unnecessary medications, intervention processes for medication reduction, and intervention effectiveness. METHODS: A systematic review of English articles using MEDLINE, EMBASE, and International Pharmaceutical Abstracts from January 1966 to September 2012. Additional studies were identified by searching bibliographies. Search terms included prescription drugs, drug utilization, hospice or palliative care, and appropriate or inappropriate. A manual review of 971 identified abstracts for the inclusion criteria (study included an intervention to reduce chronic medication use; at least 5 participants; population included patients aged at least 65 years, hospice enrollment, or indication of frailty or risk of functional decline-including assisted living or nursing home residence, inpatient hospitalization) yielded 60 articles for full review by 3 investigators. After exclusion of review articles, interventions targeting acute medications, or studies exclusively in the intensive care unit, 36 articles were retained (including 13 identified by bibliography review). Articles were extracted for study design, study setting, intervention description, criteria for identifying unnecessary medication use, and intervention outcomes. RESULTS: The studies included 15 randomized controlled trials, 4 non-randomized trials, 6 pre-post studies, and 11 case series. Control groups were used in over half of the studies (n = 20). Study populations varied and included residents of nursing homes and assisted living facilities (n = 16), hospitalized patients (n = 14), hospice/palliative care patients (n = 3), home care patients (n = 2), and frail or disabled community-dwelling patients (n = 1). The majority of studies (n = 21) used implicit criteria to identify unnecessary medications (including drugs without indication, unnecessary duplication, and lack of effectiveness); only one study incorporated patient preference into prescribing criteria. Most (25) interventions were led by or involved pharmacists, 4 used academic detailing, 2 used audit and feedback reports targeting prescribers, and 5 involved physician-led medication reviews. Overall intervention effect sizes could not be determined due to heterogeneity of study designs, samples, and measures. CONCLUSIONS: Very little rigorous research has been conducted on reducing unnecessary medications in frail older adults or patients approaching end of life.

Association between tortilla consumption and human urinary fumonisin B1 levels in a Mexican population

Fumonisins are mycotoxins produced by Fusarium spp. and commonly contaminate maize and maize products worldwide. Fumonisins are rodent carcinogens and have been associated with human esophageal cancer. However, the lack of a valid exposure biomarker has hindered both the assessment of human exposure and the evaluation of disease risk. A sensitive liquid chromatography-mass spectrometry method to measure urinary fumonisin B1 (FB1) following extraction on Oasis MAX cartridges was established and applied to urine samples from women in a cohort recruited in Morelos County, Mexico. Urinary FB1 was compared with dietary information on tortilla consumption. FB1 recovery in spiked samples averaged 94% as judged by deuterium-labeled FB1 internal standard. Urinary FB1 was determined in 75 samples from women selected based on low, medium, or high consumption of maize-based tortillas. The geometric mean (95% confidence interval) of urinary FB1 was 35.0 (18.8-65.2), 63.1 (36.8-108.2), and 147.4 (87.6-248.0) pg/mL and the frequency of samples above the detection limit (set at 20 pg FB1/mL urine) was 45%, 80%, and 96% for the low, medium, and high groups, respectively. Women with high intake had a 3-fold higher average FB1 levels compared with the "low intake" group (F = 7.3; P = 0.0015). Urinary FB1 was correlated with maize intake (P-trend = 0.001); the correlation remained significant after adjusting for age, education, and place of residence. This study suggests that measurement of urinary FB1 is sufficiently sensitive for fumonisin exposure assessment in human populations and could be a valuable tool in investigating the associated health effects of exposure.

Determinants of aflatoxin exposure in young children from Benin and Togo, West Africa: the critical role of weaning

Background Dietary exposure to high levels of the fungal toxin, aflatoxin, occurs in West Africa, where long-term crop storage facilitates fungal growth.

Methods We conducted a cross-sectional study in Benin and Togo to investigate aflatoxin exposure in children around the time of weaning and correlated these data with food consumption, socioeconomic status, agro-ecological zone of residence, and anthropometric measures. Blood samples from 479 children (age 9 months to 5 years) from 16 villages in four agro-ecological zones were assayed for aflatoxin-albumin adducts (AF-alb) as a measure of recent past (2-3 months) exposure.

Results Aflatoxin-albumin adducts were detected in 475/479 (99%) children (geometric mean 32.8 pg/mg, 95% CI: 25.3-42.5). Adduct levels varied markedly across agro-ecological zones with mean levels being approximately four times higher in the central than in the northern region. The AF-alb level increased with age up to 3 years, and within the 1-3 year age group was significantly (P=0.0001) related to weaning status; weaned children had approximately twofold higher mean AF-alb adduct levels (38 pg AF-lysine equivalents per mg of albumin [pg/mg]) than those receiving a mixture of breast milk and solid foods after adjustment for age, sex, agro-ecological zone, and socioeconomic status. A higher frequency of maize consumption, but not groundnut consumption, by the child in the preceding week was correlated with higher AF-alb adduct level. We previously reported that the prevalence of stunted growth (height for age Z-score HAZ) and being underweight (weight for age Z-score WAZ) were 33% and 29% respectively by World Health Organziation criteria. Children in these two categories had 30-40% higher mean AF-alb levels than the remainder of the children and strong dose- response relationships were observed between AF-alb levels and the extent of stunting and being underweight.

Conclusions Exposure to this common toxic contaminant of West African food increases markedly following weaning and exposure early in life is associated with reduced growth. These observations reinforce the need for aflatoxin exposure intervention strategies within high-risk countries, possibly targeted specifically at foods used in the post-weaning period.

Comparing long-term placements for young children in care: The care pathways and outcomes study - Northern Ireland

When deciding on a long-term placement for a young child in care, a key challenge is to identify one that will enable children to achieve their full potential and enhance their health and wellbeing in the longer term. However, there is a dearth of research evidence that compares how children fare in the longer term across placement options.

The Care Pathways and Outcomes study is one of a small number of studies internationally that takes this form of longitudinal comparative approach. Since 2000, it has been tracking the placement profile for a population of children who were under the age of five and in care in Northern Ireland on a particular census day, and gathering comparative data on how the children and their parents/carers have been coping across the different types of placements provided.

This book reports on the most recent phase of the study, which involved interviews with a sub-group of the children (aged 9 to 14) and their parents/carers in adoption, foster care, kinship care, on residence order, and living with birth parents. Similarities and differences were explored between placement types, in terms of children’s attachment, self-concept, education, health and behaviour, their carers’ stress, social support, family communication, and contact with birth families.

This contemporary study contributes to evidence-based practice and provides a research base for decision-making throughout the UK.