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Mild zinc deficiency, which is prevalent in vegetarians, diseased individuals, and the general aging population, depresses immunity and increases risk of disease in later life. However, human zinc intervention trials have produced conflicting results, perhaps because many of these trials included young or zinc-sufficient subjects. Since heterogeneity of the adult population may impact on response to dietary zinc, nutrigenomic approaches aimed at understanding the impact of zinc on modulation of gene and protein activities may aid in identifying subsets of the population-in particular the aging population-with increased risk of zinc deficiency who might receive benefit from a dietary zinc intervention and in this way may influence the success of the intervention. In the current study we used nutrigenomic approaches to investigate the impact of age on zinc-regulated gene expression in peripheral blood mononuclear cells. Ingenuity Pathway Analysis (Ingenuity Systems, Redwood City, CA) identified several genetic networks and functional canonical pathways which appeared responsive to zinc that were differentially regulated in young and elderly individuals. These include tryptophan metabolism, eicosanoid signaling, p38 mitogen-activated protein kinase (MAPK) signaling, integrin signaling, purine metabolism, G-protein-coupled receptor signaling, and most significantly, peroxisome proliferator-activated receptor (PPAR) signaling. These data suggest that age impacts strongly on the transcriptional effects of zinc and provides evidence to support the hypothesis that young and elderly individuals may respond differentially to zinc intervention.

Thin films of diamond-like carbon have been deposited using a photon-enhanced CVD method. Initial results have been reported previously. This paper investigates the possible mechanisms involved in film growth by electrical characterization of the plasma in the chamber, and by relating the variation in film growth rate to deposition pressure. The results indicate that the primary deposition mechanism is due to phyotolysis, with CVD due to diffusion of the hydrogen plasma from the lamp playing a lesser role. Material properties of the films have been studied by many methods, including Raman spectroscopy and elastic recoil detection analysis. These results are reported here and, in agreement with previous work, indicate that the films produced are semiconducting hydrogenated amorphous carbon, with hydrogen concentrations of between 35 and 45 at.%.

Thin films of diamond-like carbon (DLC) have been deposited using a novel photon-enhanced chemical vapour deposition (photo-CVD) method. This low energy method may be a way to produce better interfaces in electronic devices by reducing damage due to ion bombardment. Methane requires high energy photons for photolysis to take place and these are not transmitted in most photo-CVD methods owing to the presence of a window between the lamp and the deposition environment. In our photo-CVD system there is no window and all the high energy photons are transmitted into the reaction gas. Initial work has proved promising and this paper presents recent results. Films have been characterized by measuring electron energy loss spectra, by ellipsometry and by fabricating and testing diode structures. Results indicate that the films are of a largely amorphous nature and are semiconducting. Diode structures have on/off current ratios of up to 106.

Yttrium is being investigated as a hydrogen getter to prevent delayed hydride cracking in Zr-2.5Nb pressure tubes in CANDU nuclear power reactors. Yttrium strips have been encapsulated in zirconium alloy and attached to the ends of hydrided pressure tube sections to determine the effect of the degree of contact between the yttrium and the encapsulation on the gettering rate. Rates for strips hot isostatically pressed into the encapsulation were in good agreement with diffusion model predictions assuming complete contact. Rates for strips brought into contact by cold rolling were slightly lower than those for the hot-pressed strips, while little gettering was observed for loose strips sealed in the encapsulation by tungsten-inert gas welding. The effect of hydrogen flux rate to the yttrium on gettering was determined at 313°C for hydrogen fluxes from three to nine times those predicted in reactor. It was found that these fluzes did not affect the gettering rate for hydrogen concentration up to 58 at.% in the hot isostatically pressed yttrium inserts. Inserts that were thermally cycled and inserts that had not been hot pressed achieved similar gettering rates.

Decreased zinc ion availability in ageing is associated with altered immune response. One of the main regulators of zinc availability is metallothionein. Metallothionein induction is under the control of interleukin-6, a pro-inflammatory cytokine whose production is associated with poor ageing. The production of interleukin-6 is controlled, in part, by variability in the −174 nucleotide position. Under conditions of chronic inflammation, such as in ageing, zinc release by metallothionein is limited and may reduce zinc availability. Understanding the precise nature of the interactions between interleukin-6 and metallothioneins will aid in identifying individuals who are at risk of zinc deficiency. In the current study, we used gene arrays to investigate the effects of in vitro zinc supplementation on gene expression in elderly donors with described interleukin-6 and metallothionein 1a polymorphisms. Ingenuity Pathway Analysis™ identified several zinc-responsive genetic networks uniquely regulated only in elderly individuals with the pro-inflammatory interleukin-6 polymorphism. These include zinc-dependent decreased transcription of pro-inflammatory cytokines and alterations in metabolic regulatory pathways. The genomic effects of zinc increased in significance in the presence of the metallothionein 1a +647 C/A transition, suggesting that the interleukin-6 and metallothionein 1a genes act in a concerted manner to control zinc-regulated gene expression.