Studies to Characterize Heavy Metal Content and Migration From Recycled PolyethyleneTerephthalate

Packaging Materials account for 31% of the world’s municipal solid waste. Agencies like the Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR) are pushing for the increased use of recycled thermoplastic materials. Polyethylene terephthalate (PET) is a commonly recycled thermoplastic which is used to package ready-to-eat fruits and vegetables. Most recycled polyethylene terephthalate (RPET) packaging materials contain heavy metal catalysts, the most common being antimony. The recent increased use of recycled plastic materials has been suspected as the source of increased human heavy metal exposure. In this study, cadmium, chromium, nickel, lead and antimony were quantified in post-consumer RPET rigid containers and films using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Two hundred samples were tested of which 29 were found to be contaminated with heavy metals in the parts-per-million (ppm) range. Chromium was found in all the contaminated sample replicates at an average level of 8.18 ppm. Cadmium was found in all the contaminated samples as well. Lead was found in 90.4% of the contaminated samples and concentrations ranged from a low of 0.02 ppm to a high of 0.36 ppm. Nickel was found in 96.4% of the contaminated samples while antimony was found in 97.6% of the samples. Due to limited sample material, 22 of the 29 contaminated RPET rigid containers and films were tested for heavy metal migration into a 5% citric acid:water solution (w/v) or deionized water. Samples were subjected to prolonged storage at 7.2 or 22.2°C for 1, 7 or 14 days, or were exposed for 5 minutes to microwaves from a 1700-watt microwave oven set to 70% power before analysis. Leachate values were at ppb levels but were often below the ICP-AES Limits of Detection which were at also the ppb level, whether calculated for deionized water or 5% citric acid in water. No measureable levels of heavy metal were detected for any sample exposed to water, regardless of treatment. For samples exposed to 5% citrate and stored or microwaved, only chromium and nickel leached at measurable levels, and the number of RPET’s releasing measurable chromium and nickel increased with microwaving compared to the same plastics stored at 22.2 or 7.2°C. Since leaching was calculated as µg/L of heavy metal lost from the entire inner surface (1021 cm2) of a retail salad bag, actual exposure to heavy metal would be much less than measured in this study as retail fruit and vegetable packages and microwaveable pouches usually contain very little liquid in order to increase food safety. The results therefore suggest the potential for little migration of heavy metal from recycled PET to whole or fresh-cut fruits and vegetables when held at ambient or refrigerated temperatures, or when microwaved

Exile Vol. XVI No. 2

PREFACE 3 ESSAY Observations At The Gap by Paul A. Dimitruk 4 Those Who Choose Words By Keith McWalter 5-6 On Victoria\u27s England by Paul A. Dimitruk 7-8 Facts Are The Enemy of Truth by Nancy Gutierrez FICTION Harmon by Barbara Mackey 22-25 Pilgrimage by Keith McWalter 35-44 ARTWORK by Wandi Solez: 6, 15, 23, 27 by Ken Wernz 10 by Stephen Swift 11 by Laura M. Hyslop 12 by Skip Staudt 19 by W. A. Hoffman 25 by Mary Ann Kowaski 34 by Jo Ann Orgo 40 PHOTOGRAPHY by Roger Block 16 by Tim Heath- all other POETRY My Poems by Susan Hallock 13 Counter-Fugue At Six-Thirty by Sherry Stodola 14-16 Apple Tree Poem by Darby Williams 17 When Snow Falls Into A Pond by Bruce Kidd 17 Woman-Man by Darby Williams 18 Transcendence by Wandi Solez 20 Paris Reflection by Wandi Solez 20 A Sleepless Night In Valencia, Spain by Wandi Solez 21 # 319 by Wandi Solez 21 Strange Lady by John Gillespie 26 Strange Lady II by John Gillespie 26 Where The Hell Is Rembrandt? by John Loveland 26 Years Ago by John Whitt 29 I\u27ve Finished Growing Now by Keith McWalter 29 Charisma by John Whitt 30 I Thought Of Cutting by John Loveland 31 Make Me Eat Peanut Butter by Fred Walton 31 The Cat by John Loveland 32 On The Rim by John Whitt 33 Undercurrent by Keith McWalter 33 Cover: Gail Lutsch Layouts: Keith McWalte

Exile Vol. XVI No. 1

DRAMA God\u27s Pocket by Robert R. Bowie, Jr. 5-12 FICTION The Wagon by John Anderson 18-19 An Infinity of Mirrors by Keith McWalter 23-25 Commitment by John Whitt 28-29 It began not long ago... by Linda Notzelman 32-33 Jaundiced Evening by John Benes 35-39 POETRY Paralysis Outline by Lauren Shakely 13 A Woman Reads Camus by Lauren Shakely 14 don\u27t sell my rings by Lauren Shakely 14 Drift by John Whitt 17 Haiku by M. S. Wallace 19 To Begin W. K. Mayo 19 Dark is Right by Louise Tate 20 I am waiting by Louise Tate 21 My mother died as I shall die by Tim Cope 20 I never blamed you by Tim Cope 26 For Miss Didawick by Tim Cope 34 Separidian by Bill Whitmore 27 He walks on into by Whitney Carman 31 As Drowned Men Rise by Paul Bennett 34 The Tolling of the Bell by Keith McWalter 39 ARTWORK by Wandi Solez 4, 13, 16, 22, 36 by W. A. Hoffman 21, 30 by Stephen Sneeringer 27 by Christine Michael 19 Cover & Title Page Design: Keith McWalter Layouts: Keith McWalter Publicity- Special thanks to Gail Moore and Karen Baker Photographs courtesy the Sierra Club- From NOT MAN APART, Copyright 196

Quantum Mechanics and Black Holes in Four-Dimensional String Theory

In previous papers we have shown how strings in a two-dimensional target space reconcile quantum mechanics with general relativity, thanks to an infinite set of conserved quantum numbers, ``W-hair'', associated with topological soliton-like states. In this paper we extend these arguments to four dimensions, by considering explicitly the case of string black holes with radial symmetry. The key infinite-dimensional W-symmetry is associated with the $\frac{SU(1,1)}{U(1)}$ coset structure of the dilaton-graviton sector that is a model-independent feature of spherically symmetric four-dimensional strings. Arguments are also given that the enormous number of string {\it discrete (topological)} states account for the maintenance of quantum coherence during the (non-thermal) stringy evaporation process, as well as quenching the large Hawking-Bekenstein entropy associated with the black hole. Defining the latter as the measure of the loss of information for an observer at infinity, who - ignoring the higher string quantum numbers - keeps track only of the classical mass,angular momentum and charge of the black hole, one recovers the familiar a quadratic dependence on the black-hole mass by simple counting arguments on the asymptotic density of string states in a linear-dilaton background.Comment: 18 page

The SFA Business Review Vol. 3 No. 2

https://scholarworks.sfasu.edu/busreview/1005/thumbnail.jp

Examining whether and how instructional coordination occurs within introductory undergraduate STEM courses

Instructors’ interactions can foster knowledge sharing around teaching and the use of research-based instructional strategies (RBIS). Coordinated teaching presents an impetus for instructors’ interactions and creates opportunities for instructional improvement but also potentially limits an instructor’s autonomy. In this study, we sought to characterize the extent of coordination present in introductory undergraduate courses and to understand how departments and instructors implement and experience course coordination. We examined survey data from 3,641 chemistry, mathematics, and physics instructors at three institution types and conducted follow-up interviews with a subset of 24 survey respondents to determine what types of coordination existed, what factors led to coordination, how coordination constrained instruction, and how instructors maintained autonomy within coordinated contexts. We classified three approaches to coordination at both the overall course and course component levels: independent (i.e., not coordinated), collaborative (decisionmaking by instructor and others), controlled (decision-making by others, not instructor). Two course components, content coverage and textbooks, were highly coordinated. These curricular components were often decided through formal or informal committees, but these decisions were seldom revisited. This limited the ability for instructors to participate in the decision-making process, the level of interactions between instructors, and the pedagogical growth that could have occurred through these conversations. Decision-making around the other two course components, instructional methods and exams, was more likely to be independently determined by the instructors, who valued this autonomy. Participants in the study identified various ways in which collaborative coordination of courses can promote but also inhibit pedagogical growth. Our findings indicate that the benefits of collaborative course coordination can be realized when departments develop coordinated approaches that value each instructor’s autonomy, incorporate shared and ongoing decision-making, and facilitate collaborative interactions and knowledge sharing among instructors

The SFA Business Review Vol. 2 No. 2

https://scholarworks.sfasu.edu/busreview/1003/thumbnail.jp