Characterizing Silver Engineered Nanoparticles in a Natural Water: Analytical Considerations for Instrumental and Environmental Factors Using Asymmetric Flow Field Flow Fractionation

With the likely release of engineered nanoparticles into the aquatic environment, developing appropriate analytical methods for occurrence surveys has become a priority. To this end, a method towards the quantification of silver nanoparticles (AgNP) in lake water samples using asymmetric flow field flow fractionation (AF4) and inductively coupled plasma mass spectrometry (ICP-MS) is reported. Therefore, light scattering (LS) detection was used to develop an assessment metric to evaluate relative accuracy among AF4 separations. This assessment metric is applied to optimization of cross flow (Vx) protocols in AF4 separation interfaced with LS detection using mixtures of polystyrene beads. AF4 has several instrumental parameters that may have a direct effect on separation performance. A sensitivity analysis utilizing orthogonal factional factorial design and graphical analysis was applied to ascertain the relative importance of five AF4 primary/instrumental factor settings when analyzing synthetic freshwaters containing AgNPs. The most important and significant AF4 primary/instrumental factors were buffer concentration and Vx velocity, while the least impacting was Vx ramp time. Optimal settings were also generated for each of the factors within the range of settings explored. A parallel orthogonal fractional factorial design was employed to evaluate the effects of five environmental factors, or water quality characteristics, on the separation. None of these water quality characteristic effects or interactions were found to be significant. Finally, the developed methodology was applied towards AgNP quantitation in a natural lake water sample using AF4 followed by online inductively coupled plasma mass spectrometry (ICP-MS). The impacts of various AF4 system components and natural organic matter (NOM) on AgNP quantitation were explored. Isotope enriched Ag ions (Ag+) were used to identify Ag speciation following AF4 separation. Ag quantitation was achieved within 10% of a spiked “challenge” concentration of AgNP in lake water using the standard addition method to compensate for natural matrix and system complexity. Further investigations into potential Ag+-NOM and AgNP-NOM interactions were performed using fluorescence spectroscopy. The corresponding results suggest that these interactions affect the molar mass and physical conformation of the NOM particles in the sample.Doctor of Philosoph

National Outdoor Leadership School in Baja, Mexico

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1994.Includes bibliographical references (leaves 113-114).An understanding of people, program, and place establishes a foundation from which to make architectural decisions. The focus of this thesis is to understand the needs of those involved in an outdoor education school in Baja, Mexico and assemble a comprehensive architectural solution to these needs. The outdoor education school has the mission to be the best source and teacher of wilderness skills to protect the user and the environment. The people of this school share a common interest to live harmoniously with their surroundings and work to achieve a life-style that has a minimum impact on the natural environment. The site is in a desert coastal ecosystem on the east coast of the Baja peninsula. The school is acquiring additional property and has the need for a master plan that looks to their long term needs. The master plan interweaves the issues of building in a small community and the organization of the program with the natural environment. At all scales the focus of the facility is education. Building designs are direct solutions to the needs of the people in this environment. The site embodies the workings of the school and a relationship to the surrounding area. The natural environment does not act as the setting for the architecture of the school, but is seen as the focus allowing the architecture to become the framework through which one observes the natural environment.by Taylor Galyean.M.Arch

Influence of Processing Method on the Digestion of Corn Starch by Steers

Animal Scienc

Mobile Devices for Early Literacy Intervention and Research with Global Reach

Extensive work focuses on the uses of technology at scale for post-literate populations (e.g., MOOC, Learning Games, LMS’s). Little attention is afforded to non-literate populations, particularly in the developing world. This paper presents an approach using mobile devices with the ultimate goal to reach 770 million people. We developed a novel platform with a cloud backend to deliver educational content to over a thousand marginalized children in different countries:specifically, in remote villages without schools, urban slums with overcrowded schools, and at-risk, rural schools. Here we describe the theoretical basis of our system and results from case studies in three educational contexts. This model will help researchers and designers understand how mobile devices can help children acquire basic skills and aid each other’s learning when the benefit of teachers is limited or non-existent.Italian Development CouncilMRP FoundationRoanoke County School

Narrative guidance of interactivity

Thesis (Ph. D.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1995.Includes bibliographical references.by Tinsley Azariah Galyean, III.Ph.D