Ultraviolet Extinction and Visible Transparency by Ivy Nanoparticles

Though much research has been conducted for nanoparticles, naturally occurring nanoparticles have not yet been well explored for their diverse properties and potential applications. This paper reports the optical absorption and scattering properties of nanoparticles secreted by English ivy. Both experimental and theoretical studies have been conducted. Strong ultraviolet extinction and excellent visible transparency are observed, compared to the inorganic TiO2 and ZnO nanoparticles at similar concentrations. The contributions of absorption and scattering to the total extinction are quantified by simulation of the Mie scattering theory

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

DNA damage by lipid peroxidation products: implications in cancer, inflammation and autoimmunity

Oxidative stress and lipid peroxidation (LPO) induced by inflammation, excess metal storage and excess caloric intake cause generalized DNA damage, producing genotoxic and mutagenic effects. The consequent deregulation of cell homeostasis is implicated in the pathogenesis of a number of malignancies and degenerative diseases. Reactive aldehydes produced by LPO, such as malondialdehyde, acrolein, crotonaldehyde and 4-hydroxy-2-nonenal, react with DNA bases, generating promutagenic exocyclic DNA adducts, which likely contribute to the mutagenic and carcinogenic effects associated with oxidative stress-induced LPO. However, reactive aldehydes, when added to tumor cells, can exert an anticancerous effect. They act, analogously to other chemotherapeutic drugs, by forming DNA adducts and, in this way, they drive the tumor cells toward apoptosis. The aldehyde-DNA adducts, which can be observed during inflammation, play an important role by inducing epigenetic changes which, in turn, can modulate the inflammatory process. The pathogenic role of the adducts formed by the products of LPO with biological macromolecules in the breaking of immunological tolerance to self antigens and in the development of autoimmunity has been supported by a wealth of evidence. The instrumental role of the adducts of reactive LPO products with self protein antigens in the sensitization of autoreactive cells to the respective unmodified proteins and in the intermolecular spreading of the autoimmune responses to aldehyde-modified and native DNA is well documented. In contrast, further investigation is required in order to establish whether the formation of adducts of LPO products with DNA might incite substantial immune responsivity and might be instrumental for the spreading of the immunological responses from aldehyde-modified DNA to native DNA and similarly modified, unmodified and/or structurally analogous self protein antigens, thus leading to autoimmunity

TRY plant trait database - enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Sinterability of Commercial Yttria-stabilised Zirconia and the effect of sintered Density on Ionic Conduction

The sintering behaviour of a number of commercially produced 8 mol% yttria-stabilized zirconia powders has been studied. The effect of different sintering regimes on the density and microstructure of the sintered ceramic was determined using density measurements, scanning electron microscopy (SEM) and dilatometry. The chemical homogeneity, particle size and the morphology of the as-received powder were related to the sintering behaviour of the different commercial powders. Powders prepared via a route which involved a spray-drying step sintered more readily than those prepared without a spray-drying step. Plasma-derived powders did not sinter to as high an apparent density as co-precipitated powders. The effect of sample density on the ionic conductivity of sintered YSZ ceramics was studied using a.c. impedance spectroscopy. This technique allowed separation of the bulk and grain-boundary components, enabling clear intepretation of the effects of sample porosity of the conduction pathways. Ceramics prepared from the three different powders achieved a bulk ionic conductivity of similar to 16 S cm(-1) at 1000 degrees C for sintered densities of 95% or greater. The results obtained are compared to values reported for a variety of other commercial powders. (C) 1998 Kluwer Academic Publishers.</p

Influence of Yttria concentration upon Electrical Properties and Susceptibility to Ageing of Yttria-stabilised Zirconia

The most widely used electrolyte in solid oxide fuel cell (SOFC) devices is 8 mol% yttria-stablished zirconia (YSZ). Recent investigations have questioned the long term stability of this material at both the SOFC operating temperature of 1000 degrees C and during cycling between room temperature and 1000 degrees C. One possible method of improving the stability is by increasing the yttria concentration. Previous studies, utilising a number of different commercial YSZ powders have suggested that this may be possible, however, there were other differences between the samples in addition to yttria-content, notably impurity concentration. Thus the importance of yttria concentration has not been unambiguously demonstrated and the optimal content of yttria has not been determined In this study, the mechanical strength and ionic conductivity of a range of ultra-pure compositions from the (ZrO2)(1-x)(Y2O3)(x) system close to 8 mol% yttria-stabilised zirconia, x = 0.08, have been investigated. 8.5 mol% YSZ was found to have comparable mechanical strength and ionic conductivity to conventional 8 mol% YSZ, but showed improved stability. On ageing at typical fuel cell operating temperatures, i.e. 1000 degrees C, the conductivity of samples with yttria contents of 8.5 mol%, or higher, changed little; however, conductivity values for compositions with lower yttria contents decreased by 10-15%. These results strongly suggest that optimal properties are obtained for the minimum yttrium composition required to fully stabilise the cubic polymorph at the temperature of operation. (C) 1998 Elsevier Science Limited. All rights reserved.</p

Influence of Yttria concentration upon Electrical Properties and Susceptibility to Ageing of Yttria-stabilised Zirconia

The most widely used electrolyte in solid oxide fuel cell (SOFC) devices is 8 mol% yttria-stablished zirconia (YSZ). Recent investigations have questioned the long term stability of this material at both the SOFC operating temperature of 1000 degrees C and during cycling between room temperature and 1000 degrees C. One possible method of improving the stability is by increasing the yttria concentration. Previous studies, utilising a number of different commercial YSZ powders have suggested that this may be possible, however, there were other differences between the samples in addition to yttria-content, notably impurity concentration. Thus the importance of yttria concentration has not been unambiguously demonstrated and the optimal content of yttria has not been determined In this study, the mechanical strength and ionic conductivity of a range of ultra-pure compositions from the (ZrO2)(1-x)(Y2O3)(x) system close to 8 mol% yttria-stabilised zirconia, x = 0.08, have been investigated. 8.5 mol% YSZ was found to have comparable mechanical strength and ionic conductivity to conventional 8 mol% YSZ, but showed improved stability. On ageing at typical fuel cell operating temperatures, i.e. 1000 degrees C, the conductivity of samples with yttria contents of 8.5 mol%, or higher, changed little; however, conductivity values for compositions with lower yttria contents decreased by 10-15%. These results strongly suggest that optimal properties are obtained for the minimum yttrium composition required to fully stabilise the cubic polymorph at the temperature of operation. (C) 1998 Elsevier Science Limited. All rights reserved.</p