The work function of titanium and selected metals in vacuum

The work functions of titanium films have been measured at room temperature with a scanning probe version of the Kelvin-Zisman dynamic capacitor. The values for the clean surfaces of films deposited onto a gold substrate at 2.10-9 torr lay between 4.5 and 6.0 eV. The surface potentials of hydrogen were positive apparently due to penetration of the adsorbed hydrogen atom with a partial negative ionicity below the surface electronic plane. The maximum surface potential increased approximately linearly with the initial work function and varied between 0.26 and 1.30 eV. A surface potential model was proposed which attempted to account for dissociative adsorption of molecular hydrogen and solution of adsorbed atomic hydrogen. The time dependant changes of the surface potential were consistent with the theoretical predictions and the activation energy for solution of atomic hydrogen was derived to be between 0.7 and 1.5 Kcal gr-atom-1. The work function and surface potential of rapidly deposited films at 1.10-7 torr onto a silver substrate behaved similarly to those above and mass spectrometric analysis of the residual gas provided evidence for a predominant adsorption of hydrogen. Slowly deposited films at this pressure onto a silver substrate, however, possessed a low work function between 2.5 and 3.8 eV which broadly encompassed the range of values recently published by others for thin titanium films deposited apparently under similar conditions. The low values apparently arise from impurities. The surface potential of the residual gas adsorbate was negative on contaminated films and the time dependant changes were of a similar form to those of purer films. These results were discussed in relation to the hydrogen surface potential model and the adsorption of other gases. The work function of two polished stainless steel electrodes were 4.65 + 0.10 eV at 1.10-7 torr and 5.60 + 0.10 eV (after baking) at 2.10-9 torr. The work function was reversibly decreased by illumination, prolonged exposure to hydrogen and by applied electrostatic fields; it was reversibly increased by an incident electron current. These effects are interpreted as the result of an oxide layer on the steel surface. Theoretical models are proposed which attempt to account for these as due to changes in the density of surface states at a semiconducting oxide surface. The results are generally consistent with the theoretical predictions with the exception of the field effect. The effect of stray capacitive coupling on contact potential measurements was experimentally investigated. The results were partially consistent with the predictions of a model which is proposed. These effects are shown to be a major source of error if simple precautionary measures are not taken to avoid them

Families and Communities Against Child Sexual Exploitation (FCASE) : final evaluation report

This is the final evaluation report for the Barnardo’s Families and Communities Against Sexual Exploitation project (FCASE), produced by the International Centre, researching Child Sexual Exploitation, Violence and Trafficking at the University of Bedfordshire. The programme was launched in April 2013, funded by the Department for Education (DfE) and concluded in March 2015. The evaluation was undertaken during the same period. The FCASE model has been piloted in three sites, which for the purposes of this report have been anonymised and will be referred to using pseudonyms. It consists of the following elements: a structured programme of six to eight weeks direct work with young people and families where a risk of child sexual exploitation (CSE) has been identified; delivery of CSE training with professionals; and undertaking community awareness raising. The evaluation has been informed by a range of qualitative data. The report identifies the elements that work well and some of the challenges in its implementation. This had been done in order to determine good practice in supporting families and communities and embed more effective practice on protecting children and young people, including those in foster care, from sexual exploitation, harnessing the protective factors within a child’s family and/or foster home. The learning from the project is intended to help other agencies to implement the FCASE model. An on-line learning resource is to be produced in order to facilitate this process

Development of a health care policy characterisation model based on use of private health insurance

OBJECTIVE: The aim of this study was to develop a policy characterisation process based on measuring shifts in use of private health insurance (PHI) immediately following implementation of changes in federal health care policy. METHOD: Population-based hospital morbidity data from 1980 to 2001 were used to produce trend lines in the annual proportions of public, privately insured and privately uninsured hospital separations in age-stratified subgroups. A policy characterisation model was developed using visual and statistical assessment of the trend lines associated with changes in federal health care policy. RESULTS: Of eight changes in federal health care policy, two (introduction of Medicare and Lifetime Health Cover) were directly associated with major changes in the trend lines; however, minor changes in trends were associated with several of the other federal policies. Three types of policy effects were characterised by our model: direction change, magnitude change and inhibition. Results from our model suggest that a policy of Lifetime Health Cover, with a sanction for late adoption of PHI, was immediately successful in changing the private: public mix. The desired effect of the 30% rebate was immediate only in the oldest age group (70+ years), however, introduction of the lifetime health cover and limitations in the model restricted the ability to determine whether or if the rebate had a delayed effect at younger ages. CONCLUSION: An outcome-based policy characterisation model is useful in evaluating immediate effects of changes in health care policy

Mastication effects on carotenoid bioaccessibility from mango fruit tissue

The release of carotenoids from fresh fruits or vegetables is determined by the encapsulating plant tissue matrix, intracellular carotenoid location within the cell, and the mastication process. The objectives of this study were to assess the particle sizes obtained after mastication of mango fruit tissue, and how the resulting degree of plant tissue rupture affects carotenoid bioaccessibility. A fine and a coarse chewer were selected after screening 20 healthy volunteers for in vivo human mastication, and the collected chewed boluses were subjected to wet sieving fractionation, followed by an in vitro gastric and small intestinal digestion model. Confocal micrographs show that the smallest particle size fraction (0.075 mm) consists mostly of fragmented cells and the largest size fraction (2.8 mm) contains bulky clusters of whole cells and vascular fibers. Higher amounts of total carotenoids (211–320 μg/100 g) were observed in the larger particle size fraction (2.8 mm) relative to the 1 mm (192–249 μg/100 g) and 0.075 mm fractions (136–199 μg/100 g). Smaller particles showed a greater % release of total carotenoids after in vitro digestion. Xanthophyll derivatives are more bioaccessible than β-carotene for all particle sizes. The effects of particle size or degree of fine vs coarse chewing are unexpectedly small (p > 0.05), but the process of chewing substantially reduced the release of β-carotene and xanthophylls by 34% and 18%, respectively. While there is a (small) particle size effect, this appears to not be the primary factor controlling bioaccessibility for soft tissues such as mango, in contrast to previous reports that a single cell wall appears to be enough to prevent bioaccessibility of carotenoids in more robust carrot tissues

Strategic alliances and their impacts on the container shipping industry

The thesis deals with the evolution of container shipping route networks over a ten-year span from 1989 to 1999. The network evolution is shown to be a direct result of globalization, with a decline in the number of direct routes serving only two maritime ranges and a proliferation of multi-range services. A particular development has been the establishment of Strategic Alliances. Today, the industry has restructured itself around five major groupings. This paper provides an explanation for the establishment of such alliances and their influence. In particular the New World Alliance and its members will be examined in the thesis

Possible protective effect of green tea intake on risk of adult leukaemia

In a case–control study of 107 adults with leukaemia and 110 orthopaedic controls in China, a reduced risk was found with longer duration, higher quantity, and frequency of green tea intake