The prediction of failure strain for Zircaloy-4 subjected to non-stationary loading conditions

A modified Monkman-Grant relationship (MMG) is applied to predict — as far as the life time is known — the failure strain of Zry-4 subjected to tensile rupture test at load as well as temperature ramp conditions, respectively. As the analysis has shown in the first case, a simple relationship exists between the minimum creep rate and the stress rate. Thus, this quantity appearing in the MMG is phenomenologically connected with the test conditions. For failure strain predictions in temperature ramp tests the introduction of an effective temperature has shown to be advantageous. As compared to the peculiarities of the problem, the agreement between experiments and calculations is encouraging.     

Hydrodynamic behavior of a liquid-solid fluidized-bed reactor for the bioconversion of coal particles to liquid products

A predictive mathematical model based on particle convection and dispersion is presented for a liquid fluidized bed of coal particles. The numerical representation can follow transient behavior of liquid fluidized beds that contain a defined particle-size distribution. The calculations exhibited excellent agreement when compared to experimental transient pressure-drop data from a column containing particles of Illinois No. 6 bituminous coal in the size range of 20–120 μm. In addition, the model was used to simulate the effect of periodic (hourly) liquid velocity step changes on elutriation of small particles from a given particle-size distribution of 34.5–75.5 μm. For the situation tested, the calculations indicate that (a) the column does not reach a steady state between velocity changes and (b) that higher initial particle elutriation rates decay to lower values until no more particles elutriate from the column.     

Trichloroethylene uptake into fruits and vegetables: three-year field monitoring study

Trichloroethylene (TCE) contaminated groundwater migrating into communities surrounding Hill Air Force Base (HAFB) in northern Utah prompted a multiyear monitoring program (2001-2003) to examine the extent of TCE uptake and transfer into edible fruits. During the initial sampling in fall 2001, TCE was detected in a small fraction of the 167 fruit and tree core samples collected from 17 private residences. Samples were analyzed using headspace gas chromatography (GC) with electron capture detection (ECD) with limited confirmation by mass spectrometry (MS) in selected ion monitoring mode. In fall 2002, over 300 samples were collected from the same general locations sampled in 2001. No TCE was found in any of the fruit or vegetable samples above the method detection limit (MDL) for the headspace GC/MS method (approximately 0.1 microg/ kg fresh weight, depending on sample size), but TCE was again detected in several fruit tree trunk core samples. The detection of TCE in fruit in 2001, but not in 2002, may have been due to improvements in the analytical procedure or changes in the environmental conditions impacting transfer to fruit. The 2003 monitoring focused on repeated sampling over several months at five locations that were selected to represent the range of exposure scenarios evaluated during the previous years. No TCE was identified in any of the fruit above the MDL during 2003, however TCE was again found in tree core samples as observed in 2001 and 2002.     

Effects of nano-scale additives on the linear burning rate of nitromethane

This paper examines the effects of various nanoparticle additives on the combustion behavior of nitromethane, using a pressure-based method recently demonstrated by the authors to measure the linear burning rates of liquid monopropellants and heterogeneous mixtures with high precision. The linear burning rates of these mixtures were measured in a constant-volume system at chamber pressures ranging from 3 to 14 MPa, all without direct observation of the burning front. Nano-scale aluminum was used to increase the overall energy density of the mixture, fumed silica powder was used to increase the mixture thickness and encourage aluminum suspension, and nano-scale titania was also included based on its previous use as a burning rate modifier in solid propellants. The silica loading was varied from 1% to 3% by weight, aluminum was varied from 5% to 13.5% by weight, and titania was added at 1% by weight. The use of fumed silica yielded increased burning rates compared to those of neat nitromethane, and the pressure exponent of the burning rate curve shifted from lower to higher than the nitromethane baseline as more silica was added. This increased pressure sensitivity for mixtures containing 3% silica by weight was previously unobserved in similar studies by other groups and may be an effect of the higher specific surface area of the currently used silica. The subsequent addition of aluminum led to even faster burning rates and higher pressure exponents for all but one mixture. The addition of titania also led to elevated burning rates, with dramatically increased pressure sensitivity and rate inconsistency for chamber pressures above approximately 8 MPa but a decreased pressure sensitivity for the same mixture below 8 MPa. These changes in combustion behavior that accompanied titania were diminished by the presence of aluminum and completely negated in mixtures also containing fumed silica.     

Development of engineered natural organic sorbents for environmental applications: 3. Reducing PAH mobility and bioavailability in contaminated soil and sediment systems

The effects of engineered natural organic amendments on two measures of the environmental "availability" of polycyclic aromatic hydrocarbons (PAHs) associated with soil and sediment samples are assessed. Two soils spiked with pyrene alone and a sediment spiked with a mixture of 4 PAH compounds were amended with raw or superheated-water processed peat or soybean stalks, then aged for periods of either 62 or 105 days. The aged soils were then examined with respect to bioaccumulation of spiked pyrene by earthworms (Eisenia foetida), and to its human bioaccessibility as measured by extraction with simulated gastrointestinal fluid. Additions of processed amendments reduced both measures of availability by factors ranging from 7.6 to 27.0 for earthworm bioaccumulation and from 2.3 to 8.8 for gastrointestinal extractability. All PAH compounds spiked to the sediment were reduced to varying extents in their availabilities to E. foetida and leachabilities by water by both processed and raw organic amendments.     

Inhibitory effects of human and bovine milk constituents on rotavirus infections

Among etiologic agents, rotavirus is the major cause of severe dehydration diarrhea in infant mammals. In vitro and in vivo studies have indicated that the human milk-fat globule protein lactadherin inhibits rotavirus binding and protects breast-fed children against symptomatic rotavirus infection. The present work was conducted to evaluate the effect of lactadherin, along with some other milk proteins and fractions, on rotavirus infections in MA104 and Caco-2 cell lines. It is shown that human, and not bovine, lactadherin inhibits Wa rotavirus infection in vitro. Human lactadherin seems to act through a mechanism involving protein-virus interactions. The reason for the activity of human lactadherin is not clear, but it might lie within differences in the protein structure or the attached oligosaccharides. Likewise, in our hands, bovine lactoferrin did not show any suppressive activity against rotavirus. In contrast, MUC1 from bovine milk inhibits the neuraminidase-sensitive rotavirus RRV strain efficiently, whereas it has no effect on the neuraminidase-resistant Wa strain. Finally, a bovine macromolecular whey protein fraction turned out to have an efficient and versatile inhibitory activity against rotavirus.