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Adjustable-Viewing-Angle Endoscopic Tool for Skull Base and Brain Surgery

Surgeons could operate more precisely. The term “Multi-Angle and Rear Viewing Endoscopic tooL” (MARVEL) denotes an auxiliary endoscope, now undergoing development, that a surgeon would use in conjunction with a conventional endoscope to obtain additional perspective. The role of the MARVEL in endoscopic brain surgery would be similar to the role of a mouth mirror in dentistry. Such a tool is potentially useful for in-situ planetary geology applications for the close-up imaging of unexposed rock surfaces in cracks or those not in the direct line of sight.

Posted in: Briefs, TSP

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UV-Resistant Non-Spore-Forming Bacteria From Spacecraft-Assembly Facilities

Four species of non-spore-forming bacteria collected from clean-room surfaces in spacecraft-assembly facilities could survive doses of ultraviolet (UV) radiation that would suffice to kill most known cultivable bacterial species. In a previous study, high UV resistance was found in spores of the SAFR-032 strain of Bacillus pumilus, as reported in “Ultraviolet-Resistant Bacterial Spores,” NASA Tech Briefs, Vol. 31, No. 9 (September 2007), page 94. These studies are parts of a continuing effort to understand the survival of hardy species of bacteria under harsh conditions, and develop means of sterilizing spacecraft to prevent biocontamination of Mars that could in turn interfere with future life detection missions.

Posted in: Briefs

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Near-Field Spectroscopy With Nanoparticles Deposited by AFM

It is not necessary to integrate an AFM with a spectrometer. An alternative approach to apertureless near- field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used.

Posted in: Briefs

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Simplified Modeling of Oxidation of Hydrocarbons

Only a few dozen molecular and radical species are included in calculations. A method of simplified computational modeling of oxidation of hydrocarbons is undergoing development. This is one of several developments needed to enable accurate computational simulation of turbulent, chemically reacting flows. At present, accurate computational simulation of such flows is difficult or impossible in most cases because (1) the numbers of grid points needed for adequate spatial resolution of turbulent flows in realistically complex geometries are beyond the capabilities of typical supercomputers now in use and (2) the combustion of typical hydrocarbons proceeds through decomposition into hundreds of molecular species interacting through thousands of reactions. Hence, the combination of detailed reaction-rate models with the fundamental flow equations yields flow models that are computationally prohibitive. Hence, further, a reduction of at least an order of magnitude in the dimension of reaction kinetics is one of the prerequisites for feasibility of computational simulation of turbulent, chemically reacting flows.

Posted in: Briefs, TSP

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Hard-X-Ray/Soft-γ-Ray Imaging Sensor Assembly for Astronomy

A pixilated scintillator is coupled with an array of avalanche photodiodes. An improved sensor assembly has been developed for astronomical imaging at photon energies ranging from 1 to 100 keV. The assembly includes a thallium-doped cesium iodide scintillator divided into pixels and coupled to an array of high-gain avalanche photodiodes (APDs). Optionally, the array of APDs can be operated without the scintillator to detect photons at energies below 15 keV. The array of APDs is connected to compact electronic readout circuitry that includes, among other things, 64 independent channels for detection of photons in various energy ranges, up to a maximum energy of 100 keV, at a count rate up to 3 kHz. The readout signals are digitized and processed by imaging software that performs “on-the-fly” analysis.

Posted in: Briefs, TSP

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Hyperspectral Fluorescence and Reflectance Imaging Instrument

A single system contains spatial-scanning, illumination, and spectral-imaging subsystems. The system is a single hyperspectral imaging instrument that has the unique capability to acquire both fluorescence and reflectance high-spatial-resolution data that is inherently spatially and spectrally registered. Potential uses of this instrument include plant stress monitoring, counterfeit document detection, biomedical imaging, forensic imaging, and general materials identification.

Posted in: Briefs

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Light Collimator and Monitor for a Spectroradiometer

This system handles the optical input and electronic output of two spectrometers. A system that comprises optical and electronic subsystems has been developed as an infrastructure for a spectroradiometer that measures time- dependent spectral radiance of the daylight sky, in a narrow field of view (having angular width of the order of 1°) centered on the zenith, in several spectral bands in the wavelength range from 0.3 to 2.2 μm. This system is used in conjunction with two commercially available monolithic spectrometers: a silicon-based one for wavelengths from 0.3 to 1.1 μm and a gallium arsenide-based one for wavelengths from 1.05 to 2.2 μm (see figure). The role of this system is to collect the light from the affected region of the sky, collimate the light, deliver the collimated light to the monolithic spectrometers, and process the electronic outputs of the spectrometers.

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