Comparison of the Layer Structure of Vapor Phase and Leached SRL Glass by Use

ABSTRACT DE90 007789 Test samples of 131 type glass that have been reacted for extended time periods in water vapor atmospheres of different relative humidities and in static leaching solution have been examined to characterize the reaction products. Analytical electron microscopy (AEM) was used to characterize the leached samples, and a complicated layer structure was revealed, consisting of phases that precipitate from solution and also form within the residual glass layer. The precipitated phases include birnessite, saponite, and an iron species, while the intralayer phases include the LJ-Ti containing phase brannerite distributed within a matrix consisting of bands of an Fe rich montmorillonite clay. Comparison is made between samples leached at 40*C for 4 years with those leached at 90*C for 3-1/2 years. The samples reacted in water vapor were examined with scanning electron microscopy and show increasing reaction as both the relative humidity and time of reaction increases. These samples also contain a layered structure with reaction products on the glass surface

Villanova University School of Law Commencement Program - Class of 1973

The Program for the Commencement Exercises of the 18th graduating class of the Villanova University School of Law in 197

Villanova University School of Law Commencement Program - Class of 1973

The Program for the Commencement Exercises of the 18th graduating class of the Villanova University School of Law in 197

Comet Dust: The Diversity of "Primitive" Particles and Implications

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive particles has expanded significantly through microscale investigations of cosmic dust samples ( IDP's(Interplanetary Dust Particles) and AMM's (Antarctic Micrometeorites)) and of comet dust samples (Stardust and Rosetta's COSIMA), as well as through remote sensing (spectroscopy and imaging) via Spitzer and via spacecraft encounters with 103P/Hartley 2 and 67P/Churyumov-Gerasimenko. Microscale investigations show that comet dust and cosmic dust are particles of unequilibrated materials, including aggregates of materials unequilibrated at submicron scales. We call unequilibrated materials "primitive" and we deduce they were incorporated into ice-rich (H2O-, CO2-, and CO-ice) parent bodies that remained cold, i.e., into comets, because of the lack of aqueous or thermal alteration since particle aggregation; yet some Stardust olivines suggest mild thermal metamorphism. Primitive particles exhibit a diverse range of: structure and typology; size and size distribution of constituents; concentration and form of carbonaceous and organic matter; D-, N-, and O- isotopic enhancements over solar; Mg-, Fe-contents of the silicate minerals; the compositions and concentrations of sulfides, and of less abundant mineral species such as chondrules, CAIs and carbonates. The uniformity within a group of samples points to: aerodynamic sorting of particles and/or particle constituents; the inclusion of a limited range of oxygen fugacities; the inclusion or exclusion of chondrules; a selection of organics. The properties of primitive particles imply there were disk processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disk present at the time and in the region where the comets formed

Factors Leading to Students’ Satisfaction in the Higher Learning Institutions

There is an increasing need to understand factors that affect satisfaction of students with learning. This study will explore the relationship between student satisfaction and teacher-student relationship, teacher preparedness, campus support facilities and experiences provided by the institute to the students. Study is a necessary activity that most people must engage in for much of their lives to support themselves and their families; however, motivation and student satisfaction vary for students. Some students are motivated by a sense of accomplishment, some by helping others, and others by personal fulfillment. Some students get satisfied by personality grooming, personal values, and psychological needs fulfillment. The data was collected through questionnaire from the students of selected universities. This study focuses on factors that influence student satisfaction for the purpose of improving quality and thereby better performance. Keywords: Student satisfaction, Student-teacher relationship, Faculty preparedness, Campus facilities, Higher educatio

Synthesis of GEMS from Shock-accelerated Crystalline Dust in Superbubbles: Model and Predictions

GEMS (Glass Embedded with Metals and Sulfides) are highly enigmatic yet common components of anhydrous IDPs. We have recently proposed a model of GEMS formation from shock-accelerated crystalline dust in superbubbles[1] which explains the three most perplexing properties of GEMS: pseudomorphism[2], their chemistry[3], and their size range. In this Abstract, we briefly review the main points of the model, and suggest tests that will either prove or rule out this hypothesis

Electron energy-loss spectroscopy of carbon in interplanetary dust particles

The nature of the carbon-bearing phases in IDP's provides information regarding the chemical and physical processes involved in the formation and evolution of the early solar system. Several carbon-bearing materials have been observed in IDP's, but details of their nature, abundance, and distribution are still poorly known. A knowledge of the abundance and nature of carbon in IDP's is useful in constraining the sources of IDP's and for comparisons with other chondritic materials. Estimates of carbon abundance in anhydrous and hydrated IDP's indicate that most of these particles have significantly higher carbon than the carbonaceous chondrites. Mineralogical analyses show that carbonates are only a minor component of most hydrated IDP's, and so the high carbon abundances in this group of IDP's indicates that other carbon-bearing phases are present in significant concentrations. Using the technique of electron energy-loss spectroscopy (EELS), we have identified two forms of carbon in a hydrated IDP, oxidized carbon (carbonates), and amorphous elemental carbon

Agenda 1942-1943

https://digitalcommons.lasalle.edu/student_handbooks/1002/thumbnail.jp