Refine Your Search

Search Results

Viewing 1 to 3 of 3
Technical Paper

Measuring Aqueous Humor Glucose Across Physiological Levels: NIR Raman Spectroscopy, Multivariate Analysis, Artificial Neural Networks, and Bayesian Probabilities

1998-07-13
981598
We have elicited a reliable Raman spectral signature for glucose in rabbit aqueous humor across mammalian physiological ranges in a rabbit model stressed by recent myocardial infarction. The technique employs near infrared Raman laser excitation at 785 nm, multivariate analysis, non-linear artificial neural networks and an offset spectra subtraction strategy. Aqueous humor glucose levels ranged from 37 to 323 mg/dL. Data were obtained in 80 uL samples to anticipate the volume constraints imposed by the human and rabbit anterior chamber of the eye. Total sample collection time was 10 seconds with total power delivered to sample of 30 Mw. Spectra generated from the aqueous humor were compared qualitatively to artificial aqueous samples and an excitation offset technique was devised to counteract broadband background noise partially obscuring the glucose signature.
Technical Paper

Self-Sterilizing Properties of Martian Soil: Possible Nature & Implications

2000-07-10
2000-01-2343
As a result of the Viking missions in 1970s, the presence of a strong oxidant in Martian soil was suggested. Here we present a testable, by near-term missions, hypothesis that iron(VI) contributes to that oxidizing pool. Ferrate(VI) salts were studied for their spectral and oxidative properties and biological activities. Ferrate(VI) has distinctive spectroscopic features making it available for detection by remote sensing reflectance spectra and contact measurements via Mössbauer spectroscopy. The relevant miniaturized instrumentation has been developed or is underway, while XANES spectroscopy is shown to be a method of choice for the returned samples. Ferrate(VI) is capable of splitting water to yield oxygen, and oxidizing organic carbon to CO2. Organic oxidation was strongly abated after pre-heating ferrate, similar to the observations with Mars soil samples.
Journal Article

Thermal Design Trade Study for the Mars Science Laboratory ChemCam Body Unit

2009-07-12
2009-01-2462
The Mars Science Laboratory will be the next Martian mobility system that is scheduled to launch in the fall of 2011. The ChemCam Instrument is a part of the MSL science payload suite. It is innovative for planetary exploration in using a technique referred to as laser breakdown spectroscopy to determine the chemical composition of samples from distances of up to about 9 meters away. ChemCam is led by a team at the Los Alamos National Laboratory and the Centre d'Etude Spatiale des Rayonnements in Toulouse, France. The portion of ChemCam that is located inside the Rover, the ChemCam Body Unit contains the imaging charged-coupled device (CCD) detectors. Late in the design cycle, the ChemCam team explored alternate thermal design architectures to provide CCD operational overlap with the Rover's remote sensing instruments. This operational synergy is necessary to enable planning for subsequent laser firings and geological context.
X