Extraordinarily high leaf selenium to sulfur ratios define ‘se-accumulator’ plants

Background and Aims: Selenium (Se) and sulfur (S) exhibit similar chemical properties. In flowering plants (angiosperms) selenate and sulfate are acquired and assimilated by common transport and metabolic pathways. It is hypothesized that most angiosperm species show little or no discrimination in the accumulation of Se and S in leaves when their roots are supplied a mixture of selenate and sulfate, but some, termed Se-accumulator plants, selectively accumulate Se in preference to S under these conditions. Methods: This paper surveys Se and S accumulation in leaves of 39 angiosperm species, chosen to represent the range of plant Se accumulation phenotypes, grown hydroponically under identical conditions. Results: The data show that, when supplied a mixture of selenate and sulfate: (1) plant species differ in both their leaf Se ([Se]leaf) and leaf S ([S]leaf) concentrations; (2) most angiosperms show little discrimination for the accumulation of Se and S in their leaves and, in non-accumulator plants, [Se]leaf and [S]leaf are highly correlated; (3) [Se]leaf in Se-accumulator plants is significantly greater than in other angiosperms, but [S]leaf, although high, is within the range expected for angiosperms in general; and (4) the Se/S quotient in leaves of Se-accumulator plants is significantly higher than in leaves of other angiosperms. Conclusion: The traits of extraordinarily high [Se]leaf and leaf Se/S quotients define the distinct elemental composition of Se-accumulator plants

High temperature reliability of power module substrates

The thermal cycling reliability of candidate copper and aluminium power substrates has been assessed for use at temperatures exceeding 300°C peak using a combination of thermal cycling, nanoindentation and finite element modelling to understand the relative stresses and evolution of the mechanical properties. The results include the relative cycling lifetimes up to 350°C, demonstrating almost an order of magnitude higher lifetime for active metal brazed Al / AlN substrates over Cu / Si3N4, but four times more severe roughening and cracking of the Ni-P plating's on the Al / AlN (DBA) substrates. The nonlinear finite element modelling illustrated that the yield strength of the metal and the thickness of the ceramic are the main stress controlling factors, but comparisons with the cycling lifetime results demonstrated that the fracture toughness (resistance) of the ceramic is the over-riding controlling factor for the overall passive thermal cycling lifetimes. In order to achieve the highest substrate lifetime for the highly stressed high temperature thermal cycled applications, the optimum solution appears to be annealed copper, brazed on to a thicker than normal or higher fracture toughness Si3N4 ceramic

“Ignorance is not Innocence”: The Social Health Association of Indiana and Adolescent Sex Education, 1907-2007

“Ignorance is not innocence,” thundered John Hurty Secretary of the Indiana Board of Health in 1913 attempting to persuade his colleagues that only “sex knowledge” could prevent the problem of adolescent venereal disease. Throughout the twentieth century, Hurty and other Indiana reformers took the lead in national efforts to raise public awareness of the dangers of sexually transmitted diseases as part of larger debates on how to educate adolescents on the dangers of sexual activity prior to marriage This project, funded in part by the IUPUI Solution Center and Social Health Association of Indiana (SHA), seeks to use various public history methodologies to illustrate the important role Indiana played in the history of adolescent sexuality education. The history of the Social Health Association of Indiana (SHA) reflects changes not only in the sexuality education movement, but also in the broader context of adolescent sexuality, educational reform and public health movements. This project is an example of the IUPUI’s Public History Master’s program training that blends theory and hands-on experience specific to public history, often in partnership with community organizations. Today, the SHA continues their 100 year tradition of “foster successful lives by empowering youth to make responsible choices and adopt healthy behaviors.

Two droplets interaction on substrate

Dynamics of two droplets interactions on a substrate (droplet impact on a sessile droplet) are numerically investigated using OpenFOAM. The impact speed, location of the impacting droplet, viscosity and surface tension were varied in the numerical studies. We found that when the surface tension dominates the flow, the mass canter of two droplets moves to impacting droplet side. When the inertia dominates the flow, the mass centre moves to the opposite direction

Diffraction by a gap in an infinite permeable breakwater

The linearized theory of water waves is used to study the diffraction of an incident wave by a gap in a permeable breakwater. Under the assumption that the wavelength is much greater than the thickness, the breakwater is replaced by a thin barrier and a suitable boundary condition applied on the barrier to model the permeability. A new Green’s function is used in an application of Green’s theorem to obtain an integral equation which is solved numerically to obtain the flow field. An approximate solution valid for large gaps is also given. Results are presented to illustrate the effects of permeability and changes in the angle of wave incidence

Study on premixed combustion characteristics of co-firing ammonia/methane fuels

Ammonia is believed eventually play an important role in substituting conventional fossil fuels for future energy systems. In this study, to gain a deep insight into the combustion properties of co-firing ammonia/methane fuel blends for the power and steel industry, a detailed chemical-kinetics mechanism model was developed for comprehensively modelling ammonia/methane fuels combustion. Characteristics of ignition delay time, unstretched laminar burning velocity and NO, CO2 and CO emissions in the exhaust gas were obtained over a wide range of equivalence ratios and ammonia fractions. High NO emissions will be a main problem as CO and CO2 emissions tend to drop when adding ammonia into methane. To gain a further understanding of the effect of ammonia substituting methane for combustion use, analyses of laminar premixed flame structures were performed. The impact of ammonia substitution was illustrated by analysing relevant specific radicals. Furthermore, to study the combustion characteristics of ammonia/methane under more practical conditions, effects of engine relevant conditions (elevated pressure and initial temperature) were also studied. Results indicate that pressure has a more prominent effect than initial temperature and there is a good potential that unwanted emissions can be reduced significantly under industrial conditions

Modeling combustion of ammonia/hydrogen fuel blends under gas turbine conditions

To utilize ammonia as an alternative fuel for future power generation, it is essential to develop combustion chemical kinetic mechanisms which can describe in some detail the reaction characteristics and combustion properties. In the present study, a detailed chemical-kinetics mechanism is developed to validate premixed combustion characteristics of ammonia and hydrogen fuel blends comprehensively. In order to obtain a useful model for gas turbine applications, the proposed kinetic mechanism is verified in terms of NOx emission, laminar burning velocity, and ignition delay times, focusing particularly on elevated conditions which are encountered during gas turbine operation. Results have shown that the proposed kinetic model performs with satisfactory accuracy under different practical equivalence ratio conditions. The comparison with other mechanisms from the literature also demonstrates that the model can comprehensively describe the reaction process of ammonia/hydrogen fuels in terms of different combustion properties especially under gas turbine conditions. Finally, to develop the kinetic model for more practical applications, the proposed mechanism is reduced and appraised in a 2D large-eddy-simulation representing turbulent combustion for ammonia/hydrogen fuels under gas turbine conditions. The reduced mechanism shows good agreement with the parent model, while offering considerably greater computationally efficiency, hence providing optimizm for the application of detailed ammonia chemistry for future CFD analysis under gas turbine combustion conditions