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Report presents theoretical and experimental study of use of laser-induced fluorescence in oxygen to measure temperatures and densities in air flowing in hypersonic wind tunnel.
A method of detecting water-borne pathogenic bacteria is based partly on established molecular-recognition and fluorescent-labeling concepts, according to which bacteria of a species of interest are labeled with fluorescent reporter molecules and the bacteria can then be detected by fluorescence spectroscopy. The novelty of the present method lies in the use of bacteriophages (viruses that infect bacteria) to deliver the fluorescent reporter molecules to the bacteria of the species of interest.
The major goal from the animal side, however, has been achieved, namely to develop Drosophila lines where we can assay individual neuromuscular endings directly without dissection. This was achieved by means of using the GAL4-UAS system, where we have succeeded in establishing stocks of flies where the key neuromuscular connections can be assayed directly in undissected larvae by means of the expression of endogenously fluorescent reporters in the specific motor endings. The green fluorescent protein (GFP) as a reporter allows scoring of neural anatomy en-masse in whole mount using fluorescent microscopy without the need for either dissection or specific labeling. Two stocks have been developed. The first, which we developed first, uses the S65T mutant form, which has a dramatically brighter expression than the native protein. This animal will use GAL4 drivers with expression under the control of the elav gene, and which will ensure expression in all neurons of the embryo and larva. The second transgenic animal we have developed is of a novel kind, and makes use of dicistronic design, so that two copies of the protein will be expressed per insert. We have also developed a tricistronic form, but this has not yet been transformed into flies, and we do not imagine that this third line will be ready in time for the flight.
Chronic exposure to JP-8 and other kerosene-based petroleum distillates has been associated with hepatic, renal, neurologic, pulmonary, and immune toxicity. However, the effects of kerosene-type jet fuels on cellular homeostasis hitherto have not been reported. Fluorescence imaging using a Meridian Ultima laser scanning fluorescence microscope was used to evaluate the effect of JP-8 jet fuel on a communication competent rat liver cell line. Several endpoints of cellular function were measured including gap junctional intercellular communication (GJIC), mitochondrial and plasma membrane potential (MMP and PMP, respectively), intracellular glutathione (GSH) concentration, glutathione-S-transferase (GST) activity, and reactive oxygen species (ROS) generation. Cells were treated with JP-8 (0.01 to 2% in ethanol (EtOH)) for the following time points: 1 h, 24 h, 48 h, and analysis immediately after addition of jet fuel. GJIC analyzed directly after addition of 1% JP-8 was reduced 4.9-fold relative to EtOH-dosed control groups and further reduction (12.6-fold) was observed in cells treated for 1 h. Moreover, GJIC was not recoverable in cells treated with 1% JP-8 for 1 h and subsequently washed and incubated in fresh medium for 1 h. Significant changes in GSH content and GST activity were observed in cells analyzed directly after addition of 1% JP-8. GSH content increased in cells treated for 1 h with less than 2% JP-8 whereas treatment with 2% JP-8 for 1 h resulted in a 50% reduction in intracellular GSH relative to EtOH-dosed controls. Cells treated with 1% JP-8 for 48 h exhibited changes in GSH levels. However, higher JP-8 concentrations exhibited more pronounced changes in GSH and GST, which led to suppression of GSH synthesis. ROS increased in a dose-responsive fashion at JP-8 concentrations up to 1%, but decreased to 80% of control values at 2% and 3% JP-8. A 25% reduction in PMP was observed in cells treated for 1 h with 1% JP-8. In contrast, cells treated for 48 h with 2% JP-8 exhibited a 25% increase when compared to control. No significant changes were noted in the 0.01 and 1% treatment groups. Moreover, no significant changes were observed in MMP or intracellular calcium concentrations in cells treated with 0.01 to 2% JP-8 for up to 48 h. In summary, the most significant effects observed in the present study which may contribute to the toxicity of JP-8 jet fuel in cultured rat liver cells include effects on GJIC, ROS production, and GSH depletion at high (i.e., greater than 2%) JP-8 concentrations.
Although only part of the information from the X-ray fluorescence geochemical experiment has been analyzed, it is clear that the experiment was highly successful. Significant compositional differences among and possibly within the maria and highlands have been detected. When viewed in the light of analyzed lunar rocks and soil samples, and the data from other lunar orbital experiments (in particular, the Apollo 15 gamma-ray spectroscopy experiment), the results indicate the existence of a differential lunar highland crust, probably feldspathic. This crust appears to be related to the plagioclase-rich materials previously found in the samples from Apollo 11, Apollo 12, Apollo 14, Apollo 15, and Luna 16.
The lunar surface was mapped with respect to Mg, Al, and Si, as Al/Si and Mg/Si ratios along the projected ground tracks swept out by the orbiting Apollo 16 spacecraft. The results confirm the observations made during the Apollo 15 flight and provide data for a number of features not covered before. The data are consistent with the idea that the moon has a widespread differentiated crust (the highlands). The Al/Si and Mg/Si chemical ratios correspond to that for anorthositic gabbro through gabbroic anorthosites or feldspathic basalts. The X-ray results suggest the occurrence of this premare crust or material similar to it as the Descartes landing site.
Mapping of the lunar surface with respect to magnesium, aluminum, and silicon as aluminum/silicon and magnesium/silicon intensity ratios along the projected ground tracks swept out by the orbiting Apollo 16 spacecraft. The results confirm the observations made during the Apollo 15 flight and provide new data for a number of features not covered before. The data are consistent with the idea that the moon has a widespread differentiated crust (the highlands). The aluminum/silicon and magnesium/silicon concentration ratios correspond to those for anorthositic gabbros through gabbroic anorthosites or feldspathic basalts. The X-ray results suggest the occurrence of this premare crust or material similar to it at the Descartes landing site.
Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluorescence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the shot-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements.
At pressures above one megabar (100 GPa) in high-pressure diamond anvil cell experiments, the ruby fluorescence signal needed for pressure calibration is increasingly difficult to measure. A primary cause of this difficulty is the presence of an intense pressure-induced diamond fluorescence. A tentative identification of this pressure-induced fluorescence is given, a technique for the elimination of this fluorescence is reported. It is demonstrated that weak ruby signals, completely hidden by diamond fluorescence, are now easily measured with this technique.
Report describes studies conducted to establish and verify use of laser-induced fluorescence in monitoring and controlling high-temperature containerless processes. Specimens levitated by gas jets or electromagnetic fields and heated by laser beams or electromagnetic induction while being irradiated and detected by fluorescence technique. Makes quantitative and qualitative comparisons among three new methods of temperature measurement; all rely on laser-induced fluorescence. One method gas-density thermometry with seed gas. Other two methods involve measurements of velocities of evaporating atoms or of population ratios of different electronic states.
Planar laser-induced fluorescence (PLIF) of the nitric oxide (NO) molecule has been widely used in wind tunnel facilities for flow visualization, velocity, and temperature measurements. The experimental PLIF measurements are often compared with synthetic PLIF images using computationally derived temperatures, pressures, velocities, and species mole fractions. This approach is commonly referred to as computational flow imaging (CFI). In the present work, we compare signal intensity from PLIF models with experimental PLIF measurements obtained within a low pressure gas cell system at pressures and NO mole fractions relevant to supersonic and hypersonic flowfields. Experimental measurements were compared to several different laser induced-fluorescence models reported in the literature including LIFBASE, LINUS, and a NASA two-level model. The experimental measurements agreed well with all of the models at lower pressures and lower NO mole fractions; the fluorescence there is linear with both of these parameters. However, at higher pressures and mole fractions, the signal becomes nonlinear with respect to these parameters as self-quenching limits the signal and absorption further limits the signal. In fact, for the experimental path length of the experiment, the combination of high pressure and high NO mole fraction causes the experimental results to deviate significantly from the predicted results that neglect absorption of the incident laser sheet. The LINUS model, which allows absorption to be calculated, provided results that agreed better with the experimental measurements. Since supersonic and hypersonic flowfields may contain a region of the flow with high pressures and measurements in large-scale facilities often include a long path length, neglecting absorption may have a significantly negative effect on the CFI comparison to experimental PLIF images. As a result, PLIF models that account for absorption should be included in computational flow imaging approaches for laser induced fluorescence.
Measurements of the mean velocity field and selected turbulence statistics have been obtained via 2D LDA in a Mach 2 flow over a rearward facing step with downstream transverse injection. Axial mean velocity profiles, profiles of the axial and normal RMS levels, and the correlation coefficient between the axial and normal fluctuating components are presented for locations upstream of the step. These data, through comparison with other reported measurements in zero pressure gradient compressible boundary layers indicate that the boundary layers upstream of the step are consistent with 'quasi-equilibrium' turbulent boundary layers with the adiabatic wall boundary condition. Mean velocity field measurements on the symmetry plane of the tunnel are compared to laser induced iodine fluorescence measurements reported in the literature and obtained in the same facility. This comparison demonstrates the quality of the present LDA data set and shows that particle lag is not significant in the LDA measurements despite the complex nature of the downstream flow.
Genetic transformation with in vivo reporter genes for fluorescent proteins can be performed on a variety of organisms to address fundamental biological questions. Model organisms that may utilize an ISS imager include unicellular organisms (Saccharomyces cerevisiae), plants (Arabidopsis thaliana), and invertebrates (Caenorhabditis elegans). The multispectral fluorescence imager (MSFI) will have the capability to accommodate 10 cm x 10 cm Petri plates, various sized multi-well culture plates, and other custom culture containers. Features will include programmable temperature and light cycles, ethylene scrubbing (less than 25 ppb), CO2 control (between 400 ppm and ISS-ambient levels in units of 100 ppm) and sufficient airflow to prevent condensation that would interfere with imaging.
Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluoresence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the short-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements.
The excited-state dynamics of a 2-hydroxyphenylbenzotriazole (HPB) photostabilizer copolymerized with polystyrene are reported. HPB fluorescence from these copolymer films is observed at approximately 630 nm, characteristic of the proton-transferred excited state of HPB, and it has a risetime of less than 10 ps and a decay time of 28 + or - 4 ps at room temperature. Measurement of the relative fluorescence quantum yield as a function of temperature gives the activation energy for nonradiative decay of this state to be E/hc = 259 + or 25/cm.
Upon atmospheric exitre-entry and during training, astronauts are subjected to temporary periods of hypergravity, which has been implicated in the activation of oxidative stress pathways contributing to mitochondrial dysfunction and neuronal degeneration. The pathogenesis of Parkinsons disease and other neurodegenerative disorders is associated with oxidative damage to neurons involved in dopamine systems of the brain. Our study aims to examine the effects of a hypergravitational developmental environment on the degeneration of dopaminergic systems in Drosophila melanogaster. Male and female flies (Gal4-UAS transgenic line) were hatched and raised to adulthood in centrifugal hypergravity (97rpm, 3g). The nuclear expression of the reporter, Green Fluorescent Protein (GFP) is driven by the dopaminergic enzyme tyrosine hydroxylase (TH) promoter, allowing for the targeted visualization of dopamine producing neurons. After being raised to adulthood and kept in hypergravity until 18 days of age, flies were dissected and the expression of TH was measured by fluorescence confocal microscopy. TH expression in the fly brains was used to obtain counts of healthy dopaminergic neurons for flies raised in chronic hypergravity and control groups. Dopaminergic neuron expression data were compared with those of previous studies that limited hypergravity exposure to late life in order to determine the flies adaptability to the gravitational environment when raised from hatching through adulthood. Overall, we observed a significant effect of chronic hypergravity exposure contributing to deficits in dopaminergic neuron expression (p 0.003). Flies raised in 3g had on average lower dopaminergic neuron counts (mean 97.7) when compared with flies raised in 1g (mean 122.8). We suspect these lower levels of TH expression are a result of oxidative dopaminergic cell loss in flies raised in hypergravity. In future studies, we hope to further elucidate the mechanism by which hypergravity-induced oxidative stress damages the dopaminergic neuronal system, as well as examining possible chemical countermeasures to the hypergravity-induced oxidative stress response in dopaminergic neurons in order to combat cell death and consequent mental and behavioral deficits.
Upon atmospheric exitre-entry and during training, astronauts are subjected to temporary periods of hypergravity, which has been implicated in the activation of oxidative stress pathways contributing to mitochondrial dysfunction and neuronal degeneration. The pathogenesis of Parkinsons disease and other neurodegenerative disorders is associated with oxidative damage to neurons involved in dopamine systems of the brain. Our study aims to examine the effects of a hypergravitational developmental environment on the degeneration of dopaminergic systems in Drosophila melanogaster. Male and female flies (Gal4-UAS transgenic line) were hatched and raised to adulthood in centrifugal hypergravity (97rpm, 3g). The nuclear expression of the reporter, Green Fluorescent Protein (GFP) is driven by the dopaminergic enzyme tyrosine hydroxylase (TH) promoter, allowing for the targeted visualization of dopamine producing neurons. After being raised to adulthood and kept in hypergravity until 18 days of age, flies were dissected and the expression of TH was measured by fluorescence confocal microscopy. TH expression in the fly brains was used to obtain counts of healthy dopaminergic neurons for flies raised in chronic hypergravity and control groups. Dopaminergic neuron expression data were compared with those of previous studies that limited hypergravity exposure to late life in order to determine the flies adaptability to the gravitational environment when raised from hatching through adulthood. Overall, we observed a significant effect of chronic hypergravity exposure contributing to deficits in dopaminergic neuron expression (p 0.003). Flies raised in 3g had on average lower dopaminergic neuron counts (mean 97.7) when compared with flies raised in 1g (mean 122.8). We suspect these lower levels of TH expression are a result of oxidative dopaminergic cell loss in flies raised in hypergravity. In future studies, we hope to further elucidate the mechanism by which hypergravity-induced oxidative stress damages the dopaminergic neuronal system, as well as examining possible chemical countermeasures to the hypergravity-induced oxidative stress response in dopaminergic neurons in order to combat cell death and consequent mental and behavioral deficits.
An investigation is reported of the use of laser-induced fluorescence on oxygen for the measurement of air temperature and its fluctuations owing to turbulence in hypersonic wind tunnel flows. The results show that for temperatures higher than 60 K and densities higher than 0.01 amagat, the uncertainty in the temperature measurement can be less than 2 percent if it is limited by photon-statistical noise. The measurement is unaffected by collisional quenching and, if the laser fluence is kept below 1.5 J/sq cm, it is also unaffected by nonlinear effects which are associated with depletion of the absorbing states.