Corrosion protection of aluminum alloys in contact with other metals

Study establishes the quality of chemical and galvanized protection afforded by anodized and aldozided coatings applied to test panels of various aluminum alloys. The test panels, placed in firm contact with panels of titanium alloys, were subjected to salt spray tests and visually examined for corrosion effect

Undercoat prevents blistering of silver plating at elevated temperatures

Gold undercoat prevents blistering in the silver plating of Inconel 718 seals from steam at high temperatures. The undercoat is diffused into the surface of the parent metal by baking prior to silver plating

Electromotive series established for metals used in aerospace technology

Electromotive series has been established for approximately 130 commonly used aerospace metals. For most metals an initial potential and a service related potential was obtained

Effects of mixing on evolution of hydrocarbon ratios in the troposphere

Nonmethane hydrocarbon (NMHC) concentration ratios provide useful indicators of tropospheric oxidation and transport processes. However, the influences of both photochemical and mixing processes are inextricably linked in the evolution of these ratios. We present a model for investigating these influences by combining the transport treatment of the Lagrangian particle dispersion model FLEXPART with an ultrasimple (i.e., constant OH concentration) chemical treatment. Required model input includes NMHC emission ratios, but not ad hoc assumed background NMHC concentrations. The model results give NMHC relationships that can be directly compared, in a statistical manner, with measurements. The measured concentration ratios of the longest-lived alkanes show strong deviations from purely kinetic behavior, which the model nicely reproduces. In contrast, some measured aromatic ratio relationships show even stronger deviations that are not well reproduced by the model for reasons that are not understood. The model-measurement comparisons indicate that the interaction of mixing and photochemical processing prevent a simple interpretation of "photochemical age," but that the average age of any particular NMHC can be well defined and can be approximated by a properly chosen and interpreted NMHC ratio. In summary, the relationships of NMHC concentration ratios not only yield useful measures of photochemical processing in the troposphere, but also provide useful test of the treatment of mixing and chemical processing in chemical transport models. Copyright 2007 by the American Geophysical Union

Critical Cultural Consciousness in the Classroom Through an Art-Centered Curricular Unit, "Respect and Homage."

The purpose of this study was to describe the implementation, structure, content and outcome of an art-centered unit developed for 5th grade students. This unit was designed to be an example/model of specific tools and procedures that teachers can use in the art and general classroom to promote critical cultural consciousness, which is the ability to analyze both the covert and overt elements of a culture with the purpose of developing a holistic viewpoint that values the cultural heritages of self and others. The participants selected for this study were all the students in three 5th grade classes. The art-centered unit focused on three artists-Romare Bearden, Elizabeth Catlett and Charles White-under the theme "Respect and Homage." The research methods used in this investigation were qualitative. This study was written in a style that described the research design with its origins, organization and implementation. The implementation of the curricular unit developed for this study took place in the art and general classroom. Of particular interest in this study was the framework and structure of the art-centered unit, designed around two specific strategies utilized to promote critical cultural consciousness. One strategy in this unit was the identification of art-related or art-centered micro-cultures as an organizing framework for promoting critical, aesthetic inquiry of the selected works of art. Another important curricular strategy examined in this study was the utilization of personal and cultural value orientations for their role in developing cultural consciousness and critical aesthetic inquiry into works of art. Value orientations are common general issues or questions that we as people and as cultures apply various ranking patterns. Evidence of students' development of critical aesthetic inquiry into the focused works of art was documented and discussed, along with evidence of students' expanded understanding of art and culture. That evidence, added to students' personal, reflective ideas exhibited in the context of their personal art making, provided the record of students' growth in critical cultural consciousness used in this study

Statistical evaluation of the flux cross-calibration of the XMM-Newton EPIC cameras

The second XMM-Newton serendipitous source catalogue, 2XMM, provides the ideal data base for performing a statistical evaluation of the flux cross-calibration of the XMM-Newton European Photon Imaging Cameras (EPIC). We aim to evaluate the status of the relative flux calibration of the EPIC cameras on board XMM-Newton (MOS1, MOS2, and pn) and investigate the dependence of the calibration on energy, position in the field of view of the X-ray detectors, and lifetime of the mission. We compiled the distribution of flux percentage differences for large samples of 'good quality' objects detected with at least two of the EPIC cameras. The mean offset of the fluxes and dispersion of the distributions was then found by Gaussian fitting. Count rate to flux conversion was performed with a fixed spectral model. The impact on the results of varying this model was investigated. Excellent agreement was found between the two EPIC MOS cameras to better than 4% from 0.2 keV to 12.0 keV. MOS cameras register 7-9% higher flux than pn below 4.5 keV and 10-13% flux excess above 4.5 keV. No evolution of the flux ratios is seen with time, except at energies below 0.5 keV, where we found a strong decrease in the MOS to pn flux ratio with time. This effect is known to be due to a gradually degrading MOS redistribution function. The flux ratios show some dependence on distance from the optical axis in the sense that the MOS to pn flux excess increases with off-axis angle. Furthermore, in the 4.5-12.0 keV band there is a strong dependence of the MOS to pn excess flux on the azimuthal-angle. These results strongly suggest that the calibration of the Reflection Grating Array (RGA) blocking factors is incorrect at high energies. Finally, we recommend ways to improve the calculation of fluxes in future versions of XMM-Newton source catalogues.Comment: 11 pages, 10 figures, 3 tables. Abridged Abstract. Accepted for publication in Astronomy and Astrophysic