Measurements of the ultrasonic sound speed of thermosetting resins and composites can be used as an in-process cure monitoring
technique. Ultrasonic measurements have an advantage over other in-process techniques in that ultrasonic sensors do not make
contact with the part (thus leaving no imbedded sensor or witness mark) and can make true bulk measurements of the part. A
new commercially available ultrasonic cure monitoring system has been developed which easily enables ultrasonic measurements
to be made in compression molding, resin transfer molding, and autoclave processes. Advancements in ultrasonic sensor technology
enable the sensor to maintain good coupling to the part during thermal cycling to 260‡C. Data is presented showing the change
in ultrasonic sound speed during the compression molding of a graphite-epoxy prepreg. The data shows a good relationship to
the ionic conductivity and resistivity data collected via dielectric cure monitoring.
Recovery of226Ra in analysis is determined using225Ra separated by anion exchange from229Th and233U. Radium is coprecipitated with barium, and purified by ion exchange.226Ra and217At (decay product of225Ra) are measured by α-spectrometry.228Ra is determined both by β-counting228Ac and225Ac separated from228Ra and225Ra, and by α-counting its daughters after the decay of225Ra. Sources for α-spectrometry are prepared by electrodeposition (molecular plating).
The recent discovery of the migration of plutonium in groundwater away from underground nuclear tests at the Nevada Test Site has spawned considerable interest in the mechanisms by which plutonium may be released to the environment by a nuclear explosion. A suite of solid debris samples was collected during drilling through an expended test cavity and the overlying collapse chimney. Uranium and plutonium were analyzed for isotope ratios and concentrations using high precision magnetic sector inductively coupled mass spectrometry. The data unequivocally shows that plutonium may be dispersed throughout the cavity and chimney environment at the time of the detonation. The 239Pu/240Pu ratios are also fractionated relative to initial plutonium isotope ratio for the test device. Fractionation is the result of the volatilization of uranium and production of 239Pu by the reaction 238U(n,γ). We conclude that for the test under consideration plutonium was deposited outside of the confines of the cavity by dynamic processes in early-time and it is this plutonium that is most likely transferred to the groundwater regime.
Authors:P. Smith, D. Powlson, J. Smith, P. Falloon, K. Coleman, and K. Goulding
Over recent years a number of attempts have been made to assess the carbon mitigation potential of European agricultural land. Here we review the progress made by comparing pre- and post-Kyoto estimates of C mitigation potential, and review recent advances, such as the inclusion of trace gases in C mitigation calculations. We then briefly discuss ways in which our regional estimates of agricultural carbon mitigation potential might be improved. Finally, we set the findings for Europe in the context of the global terrestrial carbon cycle, and the historical global loss of carbon from soils due to agriculture.
Authors:K. Warsh, R. Buddemeier, W. Wood, and C. Smith
As part of a program to surley low levels of radioactivity in the marine environment of the southern hemisphere, we have studied the distribution and uptake of131I found in the subtidal kelp Ecklonia radiata, on the west coast of Australia. Concentrations of 5 to 75 fCi/g of131I exist in this species over a considerable distance along the coast. We have characterized the principal source of the131I and found a general temporal correlation between the amount of radioiodine discharged from sewer outfalls and its concentration in kelp. Transplant experiments have enabled us to estimate uptake and depuration rates, and our results are consistent with laboratory measurements made by others.
Authors:M. Schultz, W. Burnett, K. Inn, and G. Smith
We have developed a sequential extraction technique for determining the geochemical partitioning of Am, Pu, and U in soils
and sediments. Stable element analyses were combined with radiometric measurements to determine the most probable geochemical
host phases of these actinides in reference sediment IAEA-135.241 Am results indicate an association with carbonate minerals and organic matter. The extraction profile of238U was similar to that of refractory elements Al, Ti, and K.239/240Pu data suggest a fractionation of Pu into Fe-bearing phases of varying solubility. The reproducibility of the method was
quite good (replicates agreed to within 10% at a 95% confidence level).
Cereal breeding programs are interested in increasing the number of generations per year to reduce the time needed to develop new cultivars. A common method to accomplish this is to extend the photoperiod to speed up plant growth. For oat, this method is problematic because the species responds to changes in light and temperature. Current methods of fast generation cycling in oat require embryo rescue, which is labor intensive and has a low success rate. Recently a method was developed using increased photoperiod and foliar mineral supplement to reduce generation time for wheat and barley. We evaluated this newly published method in oat and found that anthesis occurred 15 ± 3 days faster, however there was a 3-fold reduction in seed count and a 2-fold reduction in inflorescence weight. In addition, we measured endogenous ascorbate to evaluate the physiological status of the plants under fast generation cycling conditions. For oat, fast generation cycling would be effective to more rapidly advance populations using single seed descent, but not as useful when seed yield is important.
Authors:Melanie K. Smith, Árpád Papp-Váry, and Vilmos Vass
A tanulmány célja az, hogy a nemzetköziesedő, a globális piacon versengő
intézményekben dolgozó oktatási vezetők kihívásainak és lehetőségeinek elemzését
felhasználva meghatározza, mit jelent a kreatív transzformációs vezetés a
felsőoktatás kontextusában. A tanulmány azt elemzi, hogy a felsőoktatási vezetők
szempontjából mi minősül kreatív transzformációs vezetésnek, valamint
elektronikus mélyinterjúk (e-interjúk) segítségével azt is vizsgálja, hogy a
vezetők hogyan vélekednek a fenti megközelítésekről. A mintát a szerzők online
szakmai kapcsolatrendszerén keresztül megkeresett külföldi felsőoktatási
szakemberek képezték. Az eredmények azt mutatják, hogy a vezetés kontextuális
dimenziója jelentős szerepet játszik a felsőoktatásban, különös tekintettel a
gyorsan változó társadalmi és technológiai környezetre, amely mind a dolgozók
teljesítményét, mind a hallgatók igényeit befolyásolja.
Authors:G. K. Bratspies, J. F. Smith, J. O. Hill, and P. J. Derrick
A new tin dithiocarbamate containing sulphur bridges, di-μ-sulphidobis [bis(N,N-diethyldithiocarbamato)tin(IV)], has been isolated from the thermal decomposition of tetrakis(N,N-diethyldithiocarbamato)tin(IV). A dimeric structure is proposed on the basis of results from mass spectrometry, infrared spectroscopy, thermal analysis and vapour pressure osmometry.