Laboratory procedures manual for the firefly luciferase assay for adenosine triphosphate (ATP)

A manual on the procedures and instruments developed for the adenosine triphosphate (ATP) luciferase assay is presented. Data cover, laboratory maintenance, maintenance of bacterial cultures, bacteria measurement, reagents, luciferase procedures, and determination of microbal susceptibility to antibiotics

Rare-gas optics-free stable extreme-ultraviolet photon spectrometer for solar system studies

We have developed a prototype spectrometer for space applications that require long-term stable EUV photon flux measurements. In this recently developed spectrometer, the energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer operating at a few electron volts, and followed by an electron multiplying detector, pulses due to individual electrons are counted. The overall efficiency of this process is essentially independent of gain drifts in the signal path, and the secular degradation of optical components that is often a problem in other techniques is avoided

Analytical Applications of Bioluminescence and Chemiluminescence

Bioluminescence and chemiluminescence studies were used to measure the amount of adenosine triphosphate and therefore the amount of energy available. Firefly luciferase - luciferin enzyme system was emphasized. Photometer designs are also considered

Problem areas in the use of the firefly luciferase assay for bacterial detection

By purifying the firefly luciferase extract and adding all necessary chemicals but ATP in excess, an assay for ATP was performed by measuring the amount of light produced when a sample containing soluble ATP is added to the luciferase reaction mixture. Instrumentation, applications, and basic characteristics of the luciferase assay are presented. Effect of the growth medium and length of time grown in this medium on ATP per viable E. coli values is shown in graphic form, along with an ATP concentration curve showing relative light units versus ATP injected. Reagent functions and concentration methods are explored. Efforts to develop a fast automatable system to detect the presence of bacteria in biological fluids, especially urine, resulted in the optimization of procedures for use with different types of samples

Research in the development of an improved multiplier phototube Final report

Cascade aperture design, gas pressure effects, gain calibration, and photon counting efficiency of multiplier phototub

Measurement of electric fields in the ionosphere Final report, Aug. 1966 - Sep. 1969

Measurement of electric fields in environmen

Aerometry instrumentation study Final report

Techniques and instruments for meteorological measurements in Mars and Venus atmosphere

Application of X-ray Grating Interferometry to Polymer/Flame Retardant Blends in Additive Manufacturing

X-ray grating interferometry is a nondestructive tool for visualizing the internal structures of samples. Image contrast can be generated from the absorption of X-rays, the change in phase of the beam and small-angle X-ray scattering (dark-field). The attenuation and differential phase data obtained complement each other to give the internal composition of a material and large-scale structural information. The dark-field signal reveals sub-pixel structural detail usually invisible to the attenuation and phase probe, with the potential to highlight size distribution detail in a fashion faster than conventional small-angle scattering techniques. This work applies X-ray grating interferometry to the study of additively manufactured polymeric objects. Additively manufactured bunnies made from single material—acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA)—were studied by grating-based X-ray interferometric two-dimensional imaging and tomography. The dark-field images detected poor adhesion in the plane perpendicular to the build plate. Curvature analysis of the sample perimeter revealed a slightly higher propensity to errors in regions of higher curvature. Incorporation of flame-retardant molecules to near-surface regions of otherwise flammable objects through the fused deposition modeling additive manufacturing technique was also explored. The anticipated advantage was efficient use of the flame retardants while keeping them away from the surface for safety. To determine heat propagation effects, two-dimensional grating-based interferometry imaging at LSU CAMD was used to study heated samples. The focus was on the dark-field signals to highlight voids and gaps arising from layer delamination or gasification of chemical components. The resulting differential phase and dark-field x images were tainted by fringes attributed to inaccuracies in the grating-step position. Attempts to correct this will be presented. Interferometric tomography was also carried out on the heated samples using the W. M. Keck interferometric system at LSU. Grating-based interferometry was also used to probe scattering structure sizes of heated samples. Comparison of the data with the conventional small-angle x-ray scattering technique, SAXS, is being pursued. The results obtained so far from the above-mentioned experimental works are presented in this document