581 research outputs found
Parent Participation in School Functions Following Participation in Head Start or Title I
The involvement of parents in a child\u27s schooling is an essential part of public schools and early childhood education programs. Results from previous studies indicate that this parental involvement has positive effects on a child\u27s cognitive ability and attitude toward school. This study assessed the effects of early childhood education programs, specifically Head Start and Title I, with stated parental involvement components, on a continued parental involvement in school activities as compared to children who did not attend these programs. Data collected compared the frequency of attendance for school-related functions for program participants to frequency of attendance for non-program participants. A further assessment was made on the types of these involvements, whether they were parent-initiated or teacher-initiated. This study assessed whether teacher experience (years of teaching) affected this involvement. Results indicated no significant difference in overall parent involvement between the two groups. Results did indicate a highly significant difference in parent-initiated contacts by prior participants and a nearly significant difference between teacher-initiated contacts with the prior participant group. Finally, results on teacher experience as it affects parental involvement showed no significant difference between the high (9+ years of experience) and the low (0-8 years of experience) groups
The influence of a bed load bearing tributary on the water level underneath a run-of river plant
River morphodynamics and sediment transportSediment-structure interactio
Application of the analytic hierarchy process in a comparative analysis of automated information systems
In a scientific study, we investigated decision-making methods, in particular, the methods of expert estimations to solve problems. Reflected the possibility of using the analytic hierarchy process for researching and selection of information systems in accordance with the requirements of the customer. Comparative analysis has been performed on the example of automated library information systems
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Solid Freeform Fabrication of Ceramic Parts from Filler Loaded Preceramic Polymers
Manufacturing of ceramic parts was achieved by selective laser treatment of a
preceramic polymer (polysiloxane) loaded with ceramic filler powder (alumina). Thin layers
of polymer/filler powder mixture were sequentially cured with a CO2-laser (λ=10.6 µm)
thereby generating the geometrical shape of the part. Subsequently, the cured thermoset part
was annealed in nitrogen atmosphere at 600 to 1000 °C to convert the compact into a Si-OC/Al2O3 micro-composite material. Dimensional changes upon pyrolysis (∆l/l0 ≈ 3 %) can be
controlled by adjusting the polymer-to-filler ratio and the heat treatment conditions. The new
process is called Selective Laser Curing (SLC).Financial support of Fonds der Chemischen Industrie and Deutsche
Forschungsgemeinschaft is gratefully acknowledged.Mechanical Engineerin
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INITIAL CHARACTERIZATION AND PERFORMANCE EVALUATION OF A ZIRCONIUM-BASED METALLIC WASTE FORM
A metallic waste form or alloy system for immobilization of Zircaloy cladding hulls, Undissolved Solids (UDS), Technicium (Tc) metal and Transition Metal Fission Products (TMFP) waste stream materials from separations processes for commercial spent nuclear fuel has been developed, and initial characterization of the phase assemblage and composition, and corrosion testing under aqueous conditions has been completed for the waste form with various levels of surrogate waste species. The waste stream materials are those from processes being developed as part of the Separations Campaign under the Department of Energy's (DOE's) Global Nuclear Energy Partnership (GNEP) program. The development of waste forms for these materials is under the Waste Form Campaign
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Orientation dependency of mechanical properties of 1950`s vintage Type 304 stainless steel weldment components before and after low temperature neutron irradiation
Databases of mechanical properties for both the piping and reactor vessels at the Savannah River Site (SRS) were developed from weldment components (base, weld, and weld heat-affected-zone (HAZ)) of archival piping specimens in the unirradiated and irradiated conditions. Tensile, Charpy V-notch (CVN), and Compact Tension C(T) specimens were tested at 25 and 125C before and after irradiation at low temperatures (90 to 150C) to levels of 0.065 to 2.1 dpa. irradiation hardened the weldment components and reduced the absorbed energy and toughness properties from the unirradiated values. A marked difference in the Charpy V-notch absorbed energy and the elastic-plastic fracture toughness (J{sub IC}) was observed for both the base and HAZ components with the C-L orientation being lower in toughness than the L-C orientation in both the unirradiated and irradiated conditions. Fracture surface examination of the base and HAZ components of unirradiated C(T) specimens showed a ``channel`` morphology in the fracture surfaces of the C-L specimens, whereas equiaxed ductile rupture occurred in the L-C specimens. Chromium carbide precipitation in the HAZ component reduced the fracture toughness of the C-L and L-C specimens compared to the respective base component C-L and L-C specimens. Optical metallography of the piping materials showed stringers of second phase particles parallel to the rolling direction along with a banding or modulation in the microchemistry perpendicular to the pipe axis or rolling direction of the plate material
Validation of lethality processes for products with slow come up time: Bacon and bone-in ham
Pork bellies and boneless hams were smoked or cooked using unusually long processes to determine the impact of extended come-up times on the populations of Clostridium perfringens, Salmonella enterica, Staphylococcus aureus and Listeria monocytogenes. The products were formulated using brine formulations representative of what might be used in commercial production, and the thermal processes were more than doubled in length. Pork bellies and boneless hams were inoculated on the surface as well as 1 cm below the surface, and samples were collected every 3 h. The populations of C. perfringens (spores and vegetative cells) at internal locations of pork bellies increased by less than 1 log10 and declined significantly (approximately 3 log10/cm2) on the surface of the bellies during an extended bacon process. The populations of S. enterica, L. monocytogenes and S. aureusdid not increase during the extended bacon process. The populations of C. perfringens (spores and vegetative cells), S. aureus, S. enterica and L. monocytogenesdeclined significantly over an extended ham process. There were significant population reductions (\u3e2 log10/cm2) at 7 h (surface) and 12 h (\u3e5 log10/g; internal) for the hams. Populations of both surface and internal locations of the hams declined to a point approaching the limit of detection of the assays within 17 h
Preliminary Investigation of Possible Biochar Use as Carbon Source in Polyacrylonitrile Electrospun Fiber Production
Electrospinning with consequent thermal treatment consists in a carbon fiber production method that spins a polymer solution to create fibers with diameters around a few hundred nanome-ters. The thermal treatments are used for the cyclization and then carbonization of the material at 1700◦C for one hour. The unique structure of micro-and nano-carbon fibers makes them a promis-ing material for various applications ranging from future battery designs to filtration. This work investigated the possibility of using milled gasification biochar, derived from a 20 kW fixed-bed gasifier fueled with vine pruning pellets, as an addictive in the preparation of electrospinning solu-tions. This study outlined that solvent cleaning and the consequent wet-milling and 32 µm sifting are fundamental passages for biochar preparation. Four different polyacrylonitrile-biochar shares were tested ranging from pure polymer to 50–50% solutions. The resulting fibers were analyzed via scanning electron microscopy, and energy-dispersive X-ray and infrared spectroscopy. Results from the morphological analysis showed that biochar grains dispersed themselves well among the fiber mat in all the proposed shares. All the tested solutions, once carbonized, exceeded 97%wt. of carbon content. At higher carbonization temperatures, the inorganic compounds naturally showing in biochar such as potassium and calcium disappeared, resulting in an almost carbon-pure fiber matrix with biochar grains in between
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A THEORETICAL INVESTIGATION OF RADIOLYTIC H2 GENERATION FROM SOLIDS
Hydrogen generation from materials in nuclear materials storage is of critical interest due to the potential for pressurization and/or flammability issues. Studies have focused on aqueous systems or those with minor amounts of physisorbed water, since conventional knowledge identifies the radiolytic decomposition of water as the source of H{sub 2} gas. Furthermore, the approach to characterize gas generation is typically strictly empirical, relying on determination of G-values from which production in systems is estimated. Interestingly, exploratory work at SRNL1 on gamma exposure to fully-dried solids with chemically-bound water that are typical of those produced on aluminium-clad nuclear fuel in reactor and post-discharge storage has shown a profound production of hydrogen (as the sole gaseous species) from fully dried boehmite ({gamma}-AlOOH or Al{sub 2}O{sub 3} {center_dot} H{sub 2}O) powders and no observable hydrogen from gibbsite ({gamma}-Al(OH){sub 3} or Al{sub 2}O{sub 3} {center_dot} 3H{sub 2}O) under gamma irradiation from cobalt-60. This observation is significant in that gibbsite is known to thermally decompose at 80 C whereas boehmite is stable to 400 C. Radiation damage can have various effects on solids, including heating, bond breaking, and rearrangements in the bonding structure. For example, a molecule can be ionized resulting in the generation of free electrons which can, in turn, ionize another molecule. Alternately, reactive radical species such as {lg_bullet}OH or cation species may be formed, which can go on to change bonding structures
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SPENT FUEL MANAGEMENT AT THE SAVANNAH RIVER SITE
Spent nuclear fuels are received from reactor sites around the world and are being stored in the L-Basin at the Savannah River Site (SRS) in Aiken, South Carolina. The predominant fuel types are research reactor fuel with aluminum-alloy cladding and aluminum-based fuel. Other fuel materials include stainless steel and Zircaloy cladding with uranium oxide fuel. Chemistry control and corrosion surveillance programs have been established and upgraded since the early 1990's to minimize corrosion degradation of the aluminum cladding materials, so as to maintain fuel integrity and minimize personnel exposure from radioactivity in the basin water. Recent activities have been initiated to support additional decades of wet storage which include fuel inspection and corrosion testing to evaluate the effects of specific water impurity species on corrosion attack
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