The Hawaiian Islands contain a variety of climatic regions, elevations and substrates, which are home to a large number of endemic flora and fauna. Unfortunately, these rare ecosystems and endemic species are facing a bleak future of endangerment and extinction, such as the Hawaiian lowland wet forest. Non-native and invasive plant and animal populations are currently out-competing and over-crowding native lowland species.
Archaeological surface survey is a useful, nondestructive tool for understanding the past. However, within various documents, archaeologists question the accuracy of surface artifacts to reflect the subsurface site. If surface materials mirror the site below ground, the patterns of surface artifact distribution would give archaeologists helpful insights. This project evaluated the uses, limitations, and results of archaeological site surface survey using survey data obtained from the Hungarian Copper Age site of Körösladány 14 during 2005.
Silver nanocubes 30-50 nm in diameter have been synthesized using a polyol process in which silver nitrate is reduced by ethylene glycol in the presence of a capping agent poly(vinylpyrrolidone) (PVP). A ligand exchange reaction was used to replace the PVP with another capping agent, allowing the nanocubes to be soluble in chloroform. Oleylamine, oleic acid, and decane-thiol were among the ligands investigated. The silver cubes were then used as sacrificial templates to generate hollow gold nanocages using a galvanic replacement reaction during which the silver cubes were titrated with chloroauric acid. The use of different capping agents allows us to further understand the role of the ligand in the galvanic replacement reaction.
Bacteriophage øX174 has been studied for many decades. Nonetheless, no one has ever developed a quantitative model of øX174 development. This model is important to justify the consistency of the literature data and for engineering purposes. Here, a quantitative model is developed for the intracellular øX174 proteins. By using ordinary differential equations, the change in the protein concentration is modeled as the difference between the protein synthesis and degradation rates.
Diseases such as retinitis pigmentosa and age-related macular degeneration lead to gradual loss of eyesight due to the progressive loss of retinal photoreceptors. Currently, several treatments for these diseases are being used to slow vision loss. One in particular hopes to restore partial vision by implanting an artificial retina using solar cells to provide electrical stimulation of the ganglion cells of the eye when exposed to light.
Body size (based on weaning weights) in mammals has shown varying importance for their reproductive and survival success. Therefore, size can be influential among an individual's interactions with the environment. This field study is the first to compare the body size of prairie voles (Microtus ochrogaster) and its effect on their interaction with others and overall survival while controlling the density of animals in each enclosure.
The overall goal of this project was to fabricate very sensitive microbridge Superconducting QUantum Interference Devices, SQUIDs, using electron beam lithography followed by metal deposition and lift-off. The smallest lateral dimensions in the SQUID devices are those of the Josephson junction, which is 20 nm x 20 nm. Two electron beam resists were stacked in a bi-layer in order to get both ultrahigh resolution and good lift-off.
Conventional Electron-beam lithography is done using a Scanning Electron Microscope (SEM), with a resolution limit of ~10 nm. However, there is continued need for higher resolution lithography. The goal of this project is to investigate higher resolution Electron-beam lithography using a Scanning Transmission Electron Microscope (STEM). In principle, the STEM has two main advantages: less scattering of incoming high energy electrons, and a smaller electron probe diameter. We have created 100nm wide trenches in PMMA resist, which are promising early results. Reducing the exposure of the resist will likely give higher resolution.
We have fabricated freestanding MnAs/GaAs nanowires using e-beam lithography and dry etching techniques. Nanowires as small as 75 nm in diameter were fabricated, with Magnetic Force Microscopy images of the nanowires showing the MnAs nanowire caps to be single-domain ferromagnets. The structures fabricated in this work hold promise for use in future studies of electrical spin transport.