57 resultados para Hydrochemical processes
Resumo:
Absolute cross sections have been measured for single and double charge exchange and x-ray line emission for highly charged ions of C, N, 0, and Ne colliding with He, H-2 CO2, and H2O at collisions energies of 7q keV. Present results of charge exchange in He and H-2 compare favorably with previous results. For CO2 and H2O, where prior work is scarce, the classical overbarrier model is found to overestimate results by up to a factor of 3. An analysis of the relative intensities of the observed Lyman x-ray transitions indicates that capture into l states is not statistical, as collision velocities are insufficient to populate the highest angular-momentum states. The importance of autoionization following multiple capture is highlighted, and enhanced radiative stabilization following double capture is observed and compared to other studies. Present results are also discussed in terms of mechanisms likely to generate x-ray emission in comets.
Resumo:
Germanium MOS capacitors have been fabricated with a high-? HfO dielectric using ALD. An in-situ low temperature (250°C) nitrogen plasma treatment on the germanium surface prior to the deposition of HfO was found to be beneficial to the electrical properties of the devices. Germanium MOS capacitors have also been fabricated with a SiO dielectric deposited by an atmospheric pressure CVD 'silox' process. The same low temperature plasma nitridation was found to degrade the electrical properties of the silox devices. The effect of a post-metal anneal in H and N on both types of capacitor structure was also found to degrade device electrical properties. copyright The Electrochemical Society.
Resumo:
This article highlights the importance of dedicating a whole special issue on New and Alternative Social movements in Spain. It sets the basis for this endeavour by emphasizing the importance of the 2004, unexpected, electoral victory of the Spanish socialists, and the subsequent satisfaction of the important demands promoted by certain social movements actors and Spanish society in general (the withdrawal of Spanish troops from Iraq, the cancellation of the National Hydrological Plan and the Legalization of same sex marriages. The view supported is that these developments signify the end of a protest cycle, which could have the same effect with the early 1980s socialist victory. After a discussion around the low associationalism that characterizes Spanish society and recent experience of authoritarianism, it is suggested that it is time for the study of new and alternative social movements in Spain and other south European societies to move beyond the emphasis on exceptionality but appreciate differences by focusing on the available political opportunities and the identity of social movement actors. The remainder of the article is dedicated to introducing the contributing articles.
Resumo:
There can be wide variation in the level of oral/aural language ability that prelingually hearing-impaired children develop after cochlear implantation. Automatic perceptual processing mechanisms have come under increasing scrutiny in attempts to explain this variation. Using mismatch negativity methods, this study explored associations between auditory sensory memory mechanisms and verbal working memory function in children with cochlear implants and a group of hearing controls of similar age. Whilst clear relationships were observed in the hearing children between mismatch activation and working memory measures, this association appeared to be disrupted in the implant children. These findings would fit with the proposal that early auditory deprivation and a degraded auditory signal can cause changes in the processes underpinning the development of oral/aural language skills in prelingually hearing-impaired children with cochlear implants and thus alter their developmental trajectory
Resumo:
Since 1995, when pumps were withdrawn from deep mines in East Fife (Scotland), mine waters have been rebounding throughout the coalfield. Recently, it has become necessary to pump and treat these waters to prevent their uncontrolled emergence at the surface. However, even relatively shallow pumping to surface treatment lagoons of the initially chemically-stratified mine water from a shaft in the coastal Frances Colliery during two dynamic step-drawdown tests to establish the hydraulic characteristics of the system resulted in rapid breakdown of the stratification within 24 h and a poor pumped water quality with high dissolved Fe loading. Further, data are presented here of hydrochemical and isotopic sampling of the extended pump testing lasting up to several weeks. The use in particular of the environmental isotopes d18O, d2H, d34S, 3H, 13C and 14C alongside hydrochemical and hydraulic pump test data allowed characterisation of the Frances system dynamics, mixing patterns and water quality sources feeding into this mineshaft under continuously pumped conditions. The pumped water quality reflects three significant components of mixing: shallow freshwater, seawater, and leakage from the surface treatment lagoons. In spite of the early impact of recirculating lagoon waters on the hydrochemistries, the highest Fe loadings in the longer-term pumped waters are identified with a mixed freshwater–seawater component affected by pyrite oxidation/melanterite dissolution in the subsurface system.