Multiscale Mass-Spring Models of Carbon Nanotube Arrays Accounting for Mullins-like Behavior and Permanent Deformation

Based on a one-dimensional discrete system of bistable springs, a mechanical model is introduced to describe plasticity and damage in carbon nanotube (CNT) arrays. The energetics of the mechanical system are investigated analytically, the stress-strain law is derived, and the mechanical dissipation is computed, both for the discrete case as well as for the continuum limit. An information-passing approach is developed that permits the investigation of macroscopic portions of the material. As an application, the simulation of a cyclic compression experiment on real CNT foam is performed, considering both the material response during the primary loading path from the virgin state and the damaged response after preconditioning

Geologic and Hydrologic Studies of Sites Hu1A and Hu1B in Hudspeth County, Texas

The Bureau of Economic Geology, The University of Texas at Austin, conducted preliminary investigations of the geology and hydrology of northern Hudspeth County for the Texas Low-Level Radioactive Waste Disposal Authority. The Authority had previously identified two sites, HU1A and HU1B, as possible sites for an above-ground disposal facility for low-level radioactive wastes. Regional and site-specific investigations were conducted to characterize the geology and hydrology of HU1A and HU1B. The two sites are underlain by different bedrock lithologies covered by alluvium, which necessitated drilling for site-specific investigations. Because of the lack of exposed bedrock, studies of the regional geologic setting were used to infer the probable nature of the bedrock geologic environment at each site. Hydrologic studies were predominantly regional because of the limited data available at either site and the availability of water-level data and water samples from previously drilled wells in the region.Bureau of Economic Geolog

Continuum limits of bistable spring models of carbon nanotube arrays accounting for material damage

Using chains of bistable springs, a model is derived to investigate the plastic behavior of carbon nanotube arrays with damage. We study the preconditioning effect due to the loading history by computing analytically the stress-strain pattern corresponding to a fatigue-type damage of the structure. We identify the convergence of the discrete response to the limiting case of infinitely many springs, both analytically in the framework of Gamma-convergence, as well as numerically.Comment: 11 pages, 1 figur

Geologic Review of Proposed Dallas -Fort Worth Area Site for the Superconducting Super Collider (SSC)

In June 1987, the Texas National Research Laboratory Commission tasked the Bureau of Economic Geology at The University of Texas at Austin with reviewing and providing a brief report on the geology of the proposed site for the Superconducting Super Collider (SSC) in the Dallas-Fort Worth area. Additionally, they requested a surface geologic map of the site. An informal task force was assembled for this purpose, comprising Jay A. Raney (Coordinator and Structural Geology) from the Bureau of Economic Geology, Peter M. Allen (Environmental Geology and Stratigraphy) from Baylor University, Donald F. Reaser (Structural Geology and Stratigraphy) from The University of Texas at Arlington, and Edward W. Collins (Structural Geology) from the Bureau of Economic Geology. This report by the task force provides an explanatory note for the geologic map (Plate 1) of the proposed site near Waxahachie, Texas.Bureau of Economic Geolog

Preliminary Investigation of the Geology and Hydrology of the Laska Siding Area, Hudspeth County, Texas

The Bureau of Economic Geology, The University of Texas at Austin, at the request of the Texas Low-Level Radioactive Waste Disposal Authority, conducted a preliminary investigation of the geology and hydrology of the Laska Siding area in Hudspeth County, Texas. This area is being evaluated as a potential site for a low-level radioactive waste repository to be built on State-owned lands in Trans-Pecos Texas. The Laska Siding site lies about 9 miles (14.5 km) west of the town of Sierra Blanca. The site was selected for this study because of the presence of previously mapped low-permeability sediments of the Hueco Formation, its relatively low-relief topography, and the probable great thickness of the unsaturated zone in the vicinity. The site is also attractive for a repository because of its proximity and access to a major highway and a railroad. This investigation consisted of a brief study of the geology and hydrology of the site and surrounding area. The study included a reconnaissance field evaluation of the Balson sediments, mapped faults, and geomorphology, a review of water-level and chemistry data from Texas Water Commission (TWC) Central Records for local water wells, static water level measurements of water wells in the immediate vicinity of the site, and drilling of one test hole on the proposed site.Bureau of Economic Geolog

Volume 14. Article 1. The striped bass, Roccus saxatilis.

https://elischolar.library.yale.edu/bulletin_yale_bingham_oceanographic_collection/1151/thumbnail.jp

Interactions of ingested food, beverage, and tobacco components involving human cytochrome P4501A2, 2A6, 2E1, and 3A4 enzymes.

Human cytochrome P450 (P450) enzymes are involved in the oxidation of natural products found in foods, beverages, and tobacco products and their catalytic activities can also be modulated by components of the materials. The microsomal activation of aflatoxin B1 to the exo-8,9-epoxide is stimulated by flavone and 7,8-benzoflavone, and attenuated by the flavonoid naringenin, a major component of grapefruit. P4502E1 has been demonstrated to play a potentially major role in the activation of a number of very low-molecular weight cancer suspects, including ethyl carbamate (urethan), which is present in alcoholic beverages and particularly stone brandies. The enzyme (P4502E1) is also known to be inducible by ethanol. Tobacco contains a large number of potential carcinogens. In human liver microsomes a significant role for P4501A2 can be demonstrated in the activation of cigarette smoke condensate. Some of the genotoxicity may be due to arylamines. P4501A2 is also inhibited by components of crude cigarette smoke condensate. The tobacco-specific nitrosamines are activated by a number of P450 enzymes. Of those known to be present in human liver, P4501A2, 2A6, and 2E1 can activate these nitrosamines to genotoxic products

Vaginal metastasis of a Ewing sarcoma five years after resection of the primary tumor

A 35-year-old female presented with pain and swelling of the distal left radius. A diagnosis of Ewing sarcoma was made and she underwent neoadjuvant chemotherapy and surgery. Macroscopic viable areas remained on the map of the surgical specimen; as such, she was classified as a poor responder and received high dose adjuvant chemotherapy. She remained disease-free for five years, until age 40. A vaginal polyp was then detected during a routine gynaecologic examination. It was removed and histopathology revealed metastatic Ewing sarcoma