Catalysts for ultrahigh current density oxygen cathodes for space fuel cell applications

The objective of this research was to identify promising electrocatalyst/support systems for the oxygen cathode in alkaline fuel cells operating at relatively high temperatures, O2 pressures and current densities. A number of materials were prepared, including Pb-Ru and Pb-Ir pyrochlores, RuO2 and Pt-doped RuO2, and lithiated NiO. Several of these were prepared using techniques that had not been previously used to prepare them. Particularly interesting is the use of the alkaline solution technique to prepare the Pt-doped Pb-Ru pyrochlore in high area form. Well-crystallized Pb(2)Ru(2)O(7-y) was used to fabricate high performance O2 cathodes with relatively good stability in room temperature KOH. This material was also found to be stable over a useful potential range at approximately 140 C in concentrated KOH. Other pyrochlores were found to be either unstable (amorphous samples) or the fabrication of the gas-fed electrodes could not be fully optimized during this project period. Future work may be directed at this problem. High area platinum supported on conductive metal oxide supports produced mixed results: small improvements in O2 reduction performance for Pb(2)Ru(2)O(7-y) but a large improvement for Li-doped NiO at room temperature. Nearly reversible behavior was observed for the O2/OH couple for Li-doped NiO at approximately 200 C

Characterisation and airborne deployment of a new counterflow virtual impactor inlet

A new counterflow virtual impactor (CVI) inlet is introduced with details of its design, laboratory characterisation tests and deployment on an aircraft during the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). The CVI inlet addresses three key issues in previous designs; in particular, the inlet operates with: (i) negligible organic contamination; (ii) a significant sample flow rate to downstream instruments (∼15 l min^(−1)) that reduces the need for dilution; and (iii) a high level of accessibility to the probe interior for cleaning. Wind tunnel experiments characterised the cut size of sampled droplets and the particle size-dependent transmission efficiency in various parts of the probe. For a range of counter-flow rates and air velocities, the measured cut size was between 8.7–13.1 μm. The mean percentage error between cut size measurements and predictions from aerodynamic drag theory is 1.7%. The CVI was deployed on the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter for thirty flights during E-PEACE to study aerosol-cloud-radiation interactions off the central coast of California in July and August 2011. Results are reported to assess the performance of the inlet including comparisons of particle number concentration downstream of the CVI and cloud drop number concentration measured by two independent aircraft probes. Measurements downstream of the CVI are also examined from one representative case flight coordinated with shipboard-emitted smoke that was intercepted in cloud by the Twin Otter

Attitudes and adherence to changes in nutrition and physical activity following surgery for prostate cancer:a qualitative study

OBJECTIVES: Interventions designed to improve men’s diet and physical activity (PA) have been recommended as methods of cancer prevention. However, little is known about specific factors that support men’s adherence to these health behaviour changes, which could inform theory-led diet and PA interventions. We aimed to explore these factors in men following prostatectomy for prostate cancer (PCa). DESIGN, SETTING AND PARTICIPANTS: A qualitative study using semistructured interviews with men, who made changes to their diet and/or PA as part of a factorial randomised controlled trial conducted at a single hospital in South West England. Participants were 17 men aged 66 years, diagnosed with localised PCa and underwent prostatectomy. Interview transcripts underwent thematic analysis. RESULTS: Men were ambivalent about the relationship of nutrition and PA with PCa risk. They believed their diet and level of PA were reasonable before being randomised to their interventions. Men identified several barriers and facilitators to performing these new behaviours. Barriers included tolerance to dietary changes, PA limitations and external obstacles. Facilitators included partner involvement in diet, habit formation and brisk walking as an individual activity. Men discussed positive effects associated with brisk walking, such as feeling healthier, but not with nutrition interventions. CONCLUSIONS: The facilitators to behaviour change suggest that adherence to trial interventions can be supported using well-established behaviour change models. Future studies may benefit from theory-based interventions to support adherence to diet and PA behaviour changes in men diagnosed with PCa

A hyper-mutant of the unusual σ70-Pr promoter bypasses synergistic ppGpp/DksA co-stimulation

The activities of promoters can be temporally and conditionally regulated by mechanisms other than classical DNA-binding repressors and activators. One example is the inherently weak σ70-dependent Pr promoter that ultimately controls catabolism of phenolic compounds. The activity of Pr is up-regulated through the joint action of ppGpp and DksA that enhance the performance of RNA polymerase at this promoter. Here, we report a mutagenesis analysis that revealed substantial differences between Pr and other ppGpp/DksA co-stimulated promoters. In vitro transcription and RNA polymerase binding assays show that it is the T at the −11 position of the extremely suboptimal −10 element of Pr that underlies both poor binding of σ70-RNAP and a slow rate of open complex formation—the process that is accelerated by ppGpp and DksA. Our findings support the idea that collaborative action of ppGpp and DksA lowers the rate-limiting transition energy required for conversion between intermediates on the road to open complex formation

Is there an aerosol signature of chemical cloud processing?

The formation of sulfate and secondary organic aerosol mass in the aqueous phase (aqSOA) of cloud and fog droplets can significantly contribute to ambient aerosol mass. While tracer compounds give evidence that aqueous-phase processing occurred, they do not reveal the extent to which particle properties have been modified in terms of mass, chemical composition, hygroscopicity, and oxidation state. We analyze data from several field experiments and model studies for six air mass types (urban, biogenic, marine, wild fire biomass burning, agricultural biomass burning, and background air) using aerosol size and composition measurements for particles 13–850&thinsp;nm in diameter. We focus on the trends of changes in mass, hygroscopicity parameter κ, and oxygen-to-carbon (O&thinsp;∕&thinsp;C) ratio due to chemical cloud processing. We find that the modification of these parameters upon cloud processing is most evident in urban, marine, and biogenic air masses, i.e., air masses that are more polluted than very clean air (background air) but cleaner than heavily polluted plumes as encountered during biomass burning. Based on these trends, we suggest that the mass ratio (Rtot) of the potential aerosol sulfate and aqSOA mass to the initial aerosol mass can be used to predict whether chemical cloud processing will be detectable. Scenarios in which this ratio exceeds Rtot ∼ 0.5 are the most likely ones in which clouds can significantly change aerosol parameters. It should be noted that the absolute value of Rtot depends on the considered size range of particles. Rtot is dominated by the addition of sulfate (Rsulf) in all scenarios due to the more efficient conversion of SO2 to sulfate compared to aqSOA formation from organic gases. As the formation processes of aqSOA are still poorly understood, the estimate of RaqSOA is likely associated with large uncertainties. Comparison to Rtot values as calculated for ambient data at different locations validates the applicability of the concept to predict a chemical cloud-processing signature in selected air masses.</p

Is there an aerosol signature of chemical cloud processing?

The formation of sulfate and secondary organic aerosol mass in the aqueous phase (aqSOA) of cloud and fog droplets can significantly contribute to ambient aerosol mass. While tracer compounds give evidence that aqueous-phase processing occurred, they do not reveal the extent to which particle properties have been modified in terms of mass, chemical composition, hygroscopicity, and oxidation state. We analyze data from several field experiments and model studies for six air mass types (urban, biogenic, marine, wild fire biomass burning, agricultural biomass burning, and background air) using aerosol size and composition measurements for particles 13&ndash;850&thinsp;nm in diameter. We focus on the trends of changes in mass, hygroscopicity parameter &kappa;, and oxygen-to-carbon (O&thinsp;∕&thinsp;C) ratio due to chemical cloud processing. We find that the modification of these parameters upon cloud processing is most evident in urban, marine, and biogenic air masses, i.e., air masses that are more polluted than very clean air (background air) but cleaner than heavily polluted plumes as encountered during biomass burning. Based on these trends, we suggest that the mass ratio (Rtot) of the potential aerosol sulfate and aqSOA mass to the initial aerosol mass can be used to predict whether chemical cloud processing will be detectable. Scenarios in which this ratio exceeds Rtot&sim;0.5 are the most likely ones in which clouds can significantly change aerosol parameters. It should be noted that the absolute value of Rtot depends on the considered size range of particles. Rtot is dominated by the addition of sulfate (Rsulf) in all scenarios due to the more efficient conversion of SO2 to sulfate compared to aqSOA formation from organic gases. As the formation processes of aqSOA are still poorly understood, the estimate of RaqSOA is likely associated with large uncertainties. Comparison to Rtot values as calculated for ambient data at different locations validates the applicability of the concept to predict a chemical cloud-processing signature in selected air masses.</p

An analysis of first-time enquirers to the CancerBACUP information service: variations with cancer site, demographic status and geographical location

A retrospective comparison of cancer incidence data and, where relevant, population data with 16 955first-time users (patients, relatives and friends) of a national cancer information service (CancerBACUP) during the period April1995 to March 1996 is presented. The number of events observed was compared with the number of events expected, were the nationalrates of cancer incidence and population demographics apply. Standardized incidence ratios (SIRs) (observed – expectedratios) were used to indicate any differences. Statistically significant differences (P< 0.001) in the observed andexpected sex, age and primary site distribution of patients enquired about were found. Statistically significant differences(P< 0.001) were also identified for the age, employment status, socioeconomic class and geographical location offirst-time enquirers (patients, relatives and friends). Enquiries about brain, testis and breast cancers and non-Hodgkin'slymphoma (NHL) were substantially higher than expected; enquiries about bladder, lung, stomach and colorectal cancers were muchlower than expected. As the service is provided via a freephone number, it is available to all, and users might be expected to berandomly distributed across the variables listed. The underlying reasons for the differences identified need to be investigated,and the role of information in the care of cancer patients should be formally evaluated. © 1999 Cancer Research Campaig