80 research outputs found
Maximally incompressible neutron star matter
Relativistic kinetic theory, based on the Grad method of moments as developed
by Israel and Stewart, is used to model viscous and thermal dissipation in
neutron star matter and determine an upper limit on the maximum mass of neutron
stars. In the context of kinetic theory, the equation of state must satisfy a
set of constraints in order for the equilibrium states of the fluid to be
thermodynamically stable and for perturbations from equilibrium to propagate
causally via hyperbolic equations. Application of these constraints to neutron
star matter restricts the stiffness of the most incompressible equation of
state compatible with causality to be softer than the maximally incompressible
equation of state that results from requiring the adiabatic sound speed to not
exceed the speed of light. Using three equations of state based on experimental
nucleon-nucleon scattering data and properties of light nuclei up to twice
normal nuclear energy density, and the kinetic theory maximally incompressible
equation of state at higher density, an upper limit on the maximum mass of
neutron stars averaging 2.64 solar masses is derived.Comment: 8 pages, 2 figure
Effect of compost-, sand-, or gypsum-amended waste foundry sands on turfgrass yield and nutrient content
To prevent the 7 to 11 million metric tons of waste foundry
sand (WFS) produced annually in the USA from entering
landfi lls, current research is focused on the reuse of WFSs as
soil amendments. Th e eff ects of diff erent WFS-containing
amendments on turfgrass growth and nutrient content were
tested by planting perennial ryegrass (Lolium perenne L.) and
tall fescue (Schedonorus phoenix (Scop.) Holub) in diff erent
blends containing WFS. Blends of WFS were created with
compost or acid-washed sand (AWS) at varying percent by
volume with WFS or by amendment with gypsum (9.6 g
gypsum kg–1 WFS). Measurements of soil strength, shoot and
root dry weight, plant surface coverage, and micronutrients (Al,
Fe, Mn, Cu, Zn, B, Na) and macronutrients (N, P, K, S, Ca,
Mg) were performed for each blend and compared with pure
WFS and with a commercial potting media control. Results
showed that strength was not a factor for any of the parameters
studied, but the K/Na base saturation ratio of WFS:compost
mixes was highly correlated with total shoot dry weight for
perennial ryegrass (r = 0.995) and tall fescue (r = 0.94). Th is was
further substantiated because total shoot dry weight was also
correlated with shoot K/Na concentration of perennial ryegrass
(r = 0.99) and tall fescue (r = 0.95). A compost blend containing
40% WFS was determined to be the optimal amendment for
the reuse of WFS because it incorporated the greatest possible
amount of WFS without major reduction in turfgrass growth
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Conceptual design characteristics of a denatured molten-salt reactor with once-through fueling
A study was made to examine the conceptual feasibility of a molten-salt power reactor fueled with denatured /sup 235/U and operated with a minimum of chemical processing. Because such a reactor would not have a positive breeding gain, reductions in the fuel conversion ratio were allowed in the design to achieve other potentially favorable characteristics for the reactor. A conceptual core design was developed in which the power density was low enough to allow a 30-year life expectancy of the moderator graphite with a fluence limit of 3 x 10/sup 26/ neutrons/m/sup 2/ (E > 50 keV). This reactor could be made critical with about 3450 kg of 20% enriched /sup 235/U and operated for 30 years with routine additions of denatured /sup 235/U and no chemical processing for removal of fission products. A review of the chemical considerations assoicated with the conceptual fuel cycle indicates that no substantial difficulties would be expected if the soluble fission products and higher actinides were allowed to remain in the fuel salt for the life of the plant
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Caseinoglycomacropeptide inhibits adhesion of pathogenic Escherichia coli strains to human cells in culture
Caseinoglycomacropeptide (CGMP) derived from kappa-casein was investigated for its ability to inhibit the adhesion of 3 strains of verotoxigenic Escherichia coli (VTEC) and 3 strains of enteropathogenic Escherichia coli (EPEC) to human HT29 tissue cell cultures. Effects on adhesion of Desulfovibrio desulfuricans, Lactobacillus pentosus, Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus gasseri were also investigated. Generally, CGMP exerted effective anti-adhesive properties at a dose of 2.5 mg/mL, albeit with a high degree of strain specificity. The CGMP reduced adhesion of VTEC strains to < 50% of the control and reduced adhesion of EPEC strains to between 80 and 10% of the control. The CGMP also reduced the adhesion of L. pentosus and L. casei to 44 and 42%, respectively. A slight but significant reduction of L. acidophilus, to 81%, was observed, but no significant effects were detected with either Dsv. desulfuricans or L. gasseri. Further investigation of the dose response relationships with the E. coli strains gave IC50 values ranging between 0.12 and 1.06 mg/mL
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