Tests on Models of Nuclear Reactor Elements - Head Losses in Core Sub-Assemblies

Losses have been determined for flow through models of various proposed core sub-assemblies as part of a study of the elements of a nuclear reactor. Six core sections and two? axial blanket sub-assemblies have been compared on the basis of drop in piezometric. head or pressure drop. The core sub-assemblies are composed of an entrance nozzle, a lower axial blanket section, the core section, an upper axial blanket section, and a short section for the handling lug. The four parts of the sub-assembly other than the core section are designated as the axial blanket sub-assembly. In each core section there are 144 rods within a container which has a square cross-section. The primary differences between one core section and another are the means qf supporting and spacing the rods. Bars or wires wrapped in spirals around the rods were used as well as a series of grids made up of wires and supported at the four corners. Also, in one core an, inner wall was used to provide an annular flow passage which helps to reduce the difference in temperature at the inner and outer walls of the core. The two axial blanket sub-assemblies tested are similar except ?that the second model is characterized by more gradual transitions in changes of cross section. Other parts of this study of the elements of a nuclear reactor have been described in two previous reports dealing with head losses in complete blanket subassemblies and with diffusion studies

Tests on Models of Nuclear Reactor Elements - Head Losses in Core Sub-Assemblies

Losses have been determined for flow through models of various proposed core sub-assemblies as part of a study of the elements of a nuclear reactor. Six core sections and two? axial blanket sub-assemblies have been compared on the basis of drop in piezometric. head or pressure drop. The core sub-assemblies are composed of an entrance nozzle, a lower axial blanket section, the core section, an upper axial blanket section, and a short section for the handling lug. The four parts of the sub-assembly other than the core section are designated as the axial blanket sub-assembly. In each core section there are 144 rods within a container which has a square cross-section. The primary differences between one core section and another are the means qf supporting and spacing the rods. Bars or wires wrapped in spirals around the rods were used as well as a series of grids made up of wires and supported at the four corners. Also, in one core an, inner wall was used to provide an annular flow passage which helps to reduce the difference in temperature at the inner and outer walls of the core. The two axial blanket sub-assemblies tested are similar except ?that the second model is characterized by more gradual transitions in changes of cross section. Other parts of this study of the elements of a nuclear reactor have been described in two previous reports dealing with head losses in complete blanket subassemblies and with diffusion studies

Site-Specific Labeling of Annexin V with F-18 for Apoptosis Imaging

Annexin V is useful in detecting apoptotic cells by binding to phosphatidylserine (PS) that is exposed on the outer surface of the cell membrane during apoptosis. In this study, we examined the labeling of annexin V-128, a mutated form of annexin V that has a single cysteine residue at the NH2 terminus, with the thiol-selective reagent 18F-labeling agent N-[4-[(4-[18F]fluorobenzylidene)aminooxy]butyl]maleimide ([18F]FBABM). We also examined the cell binding affinity of the 18F-labeled annexin V-128 ([18F]FAN-128). [18F]FBABM was synthesized in two-step, one-pot method modified from literature procedure. (Toyokuni et al., Bioconjugate Chem. 2003, 14, 1253−1259). The average yield of [18F]FBABM was 23 ± 4% (n = 4, decay-corrected) and the specific activity was ∼6000 Ci/mmol. The total synthesis time was ∼92 min. The critical improvement of this study was identifying and then developing a purification method to remove an impurity N-[4-[(4-dimethylaminobenzylidene)aminooxy]butyl]maleimide 4, whose presence dramatically decreased the yield of protein labeling. Conjugation of [18F]FBABM with the thiol-containing annexin V-128 gave [18F]FAN-128 in 37 ± 9% yield (n = 4, decay corrected). Erythrocyte binding assay of [18F]FAN-128 showed that this modification of annexin V-128 did not compromise its membrane binding affinity. Thus, an in vivo investigation of [18F]FAN-128 as an apoptosis imaging agent is warranted

Effects of Ethanol and NAP on Cerebellar Expression of the Neural Cell Adhesion Molecule L1

The neural cell adhesion molecule L1 is critical for brain development and plays a role in learning and memory in the adult. Ethanol inhibits L1-mediated cell adhesion and neurite outgrowth in cerebellar granule neurons (CGNs), and these actions might underlie the cerebellar dysmorphology of fetal alcohol spectrum disorders. The peptide NAP potently blocks ethanol inhibition of L1 adhesion and prevents ethanol teratogenesis. We used quantitative RT-PCR and Western blotting of extracts of cerebellar slices, CGNs, and astrocytes from postnatal day 7 (PD7) rats to investigate whether ethanol and NAP act in part by regulating the expression of L1. Treatment of cerebellar slices with 20 mM ethanol, 10−12 M NAP, or both for 4 hours, 24 hours, and 10 days did not significantly affect L1 mRNA and protein levels. Similar treatment for 4 or 24 hours did not regulate L1 expression in primary cultures of CGNs and astrocytes, the predominant cerebellar cell types. Because ethanol also damages the adult cerebellum, we studied the effects of chronic ethanol exposure in adult rats. One year of binge drinking did not alter L1 gene and protein expression in extracts from whole cerebellum. Thus, ethanol does not alter L1 expression in the developing or adult cerebellum; more likely, ethanol disrupts L1 function by modifying its conformation and signaling. Likewise, NAP antagonizes the actions of ethanol without altering L1 expression

The use of computers in naval architecture education

http://deepblue.lib.umich.edu/bitstream/2027.42/8368/5/bad6042.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/8368/4/bad6042.0001.001.tx

Experimental investigation of green sea loadings on deckhouse geometry for a destroyer-type model

http://deepblue.lib.umich.edu/bitstream/2027.42/8367/5/bad6098.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/8367/4/bad6098.0001.001.tx

Tests on Models of Nuclear Reactor Elements - Studies of Diffusion

To estimate the distribution of temperature in the proposed nuclear reactor, one must determine a coefficient of eddy diffusivity and devise a suitable method of computing the heat transfer. Measurements of diffusion in a model of a blanket element for the proposed reactor indicated a gross eddy diffusion coefficient of about 0.002 (? .0005) ft{sup 2}/sec. Thus, the apparent eddy diffusion for the test conditions is about 200 times the molecular diffusivity of water and about. twice that of the liquid sodium. Even approximate methods of applying this result require an elaborate calculation if the primary characteristics of the flow system are to be taken into account. The dispersion of dye in flowing water provided an indication of the diffusion in the model tests. The presence and arrangement of the rods, the effect on the flow?of the spiral wire spacers, and the existence of a comparatively large area on which a laminar sub-layer develops made it impossible to get simple turbulence criteria like those obtained downstream from a screen. Although the results are consequently somewhat unsystematic, they do establish reliably the approximate magnitude of the coefficient of eddy diffusivity. The data were obtained from both line and sectional traverses, the two results being approximately equal. Preliminary data were also obtained for a core element for which {epsilon} ~ 0.003, only slightly less than for the blanket element. Determination of the diffusion coefficient makes it possible to compute the temperature for an array of spatially variable heat sources, as occur in any element. Because of the extreme complexity of the problem, two alternative simplifying assumptions are proposed., In one, the heat sources are assumed to be concentrated along their axes. In the other, the heat is assumed to pass to the fluid immediately at the surface of each circular rod and then to diffuse as though no other rods were present. In each case the effect of the rods on the pattern of diffusion is taken into account only by the afore-mentioned ratio between the local and the apparent diffusivities. The calculations involve a doubly infinite summation to account for the rods and for the so\id walls of the container which are assumed to be insulated. An effect of the rods is to make the local diffusivity much more than the apparent diffusivity, which was observed. In a calculation based on an analogy with heat transfer, the former was found to be 5.3 times the latter