Quantitative analysis of ice films by near-infrared spectroscopy

One of the outstanding problems in the Space Transportation System is the possibility of the ice buildup on the external fuel tank surface while it is mounted on the launch pad. During the T-2 hours (and holding) period, the frost/ice thickness on the external tank is monitored/measured. However, after the resumption of the countdown time, the tank surface can only be monitored remotely. Currently, remote sensing is done with a TV camera coupled to a thermal imaging device. This device is capable of identifying the presence of ice, especially if it is covered with a layer of frost. However, it has difficulty identifying transparent ice, and, it is not capable of determining the thickness of ice in any case. Thus, there is a need for developing a technique for measuring the thickness of frost/ice on the tank surface during this two hour period before launch. The external tank surface is flooded with sunlight (natural or simulated) before launch. It may be possible, therefore, to analyze the diffuse reflection of sunlight from the external tank to determine the presence and thickness of ice. The purpose was to investigate the feasibility of this approach. A near-infrared spectrophotometer was used to record spectra of ice. It was determined that the optimum frequencies for monitoring the ice films were 1.03 and 1.255 microns

Characterization of the surfaces of platinum/tin oxide based catalysts by Fourier transform spectroscopy (FTIR)

The Laser Atmospheric Wind Sounder (LAWS) Program has as one of its goals the development of a satellite based carbon dioxide laser for making wind velocity measurements. The specifications for this laser include the requirement that the laser operate at a repetition rate of 10 Hertz continuously for three years. Earth-based carbon dioxide lasers can operate for only a short time on a single charge of gas because the lasing action causes the CO2 to break down into CO and O2. Therefore, earth-based CO2 lasers are generally operated in a flow through mode in which the spent gas is continually exhausted and fresh gas is continually added. For a satellite based system, however, a recirculation system is desired because it is not practical to send up extra tanks of CO2. A catalyst which could enable a recirculating CO2 laser to function continuously for three years needs to be developed. In the development of a catalyst system there are many variables. Obviously, not all possible formulations can be tested for three years, therefore, an accurate model which is based on the reaction mechanism is needed. The construction of a multistep reaction mechanism is similar to the construction of a jigsaw puzzle. Different techniques each supply a piece of the puzzle and the researcher must put the pieces together. Transmission infrared spectroscopy was shown to be very useful in supplying some of the information needed to elucidate reaction mechanisms. The purpose was to see what kind of information might be obtained about the NASA catalyst using infrared absorption spectroscopy. Approximately 200 infrared spectra of the prototype Pt/tin oxide catalyst and its precursor components are observed under a variety of different conditions. The most significant observations are summarized

Characterization of the surfaces of platinum/tin oxide based catalysts by Fourier Transform Infrared Spectroscopy (FTIR)

A Pt/SnO2 catalyst has been developed at NASA Langley that is effective for the oxidation of CO at room temperature (1). A mechanism has been proposed to explain the effectiveness of this catalyst (2), but most of the species involved in this mechanism have not been observed under actual catalytic conditions. A number of these species are potentially detectable by Fourier Transform Infrared Spectroscopy (FTIR), e.g., HOSnO sub x, HO sub y PtO sub z, Pt-CO, and SnHCO3. Therefore a preliminary investigation was conducted to determine what might be learned about this particular catalyst by transmission FTIR. The main advantage of FTIR for this work is that the catalyst can be examined under conditions similar to the actual catalytic conditions. This can be of critical importance since some surface species may exist only when the reaction gases are present. Another advantage of the infrared approach is that since vibrations are probed, subtle chemical details may be obtained. The main disadvantage of this approach is that FTIR is not nearly as sensitive as the Ultra High Vacuum (UHV) surface analytical techniques such as Auger, Electron Spectroscopy for Chemical Analysis (ESCA), Electron Energy Loss Spectroscopy (EELS), etc. Another problem is that the assignment of the observed infrared bands may be difficult

Consequences of the Clean Water Act and the Demand for Water Quality

Since the 1972 U.S. Clean Water Act, government and industry have invested over $1 trillion to abate water pollution, or$100 per person-year. Over half of U.S. stream and river miles, however, still violate pollution standards. We use the most comprehensive set of files ever compiled on water pollution and its determinants, including 50 million pollution readings from 170,000 monitoring sites, to study water pollution\u27s trends, causes, and welfare consequences. We have three main findings. First, water pollution concentrations have fallen substantially since 1972, though were declining at faster rates before then. Second, the Clean Water Act\u27s grants to municipal wastewater treatment plants caused some of these declines. Third, the grants\u27 estimated effects on housing values are generally smaller than the grants\u27 costs

Effect of indomethacin and adrenocorticotrophic hormone on renal function in man: An experimental model of inappropriate antidiuresis

Effect of indomethacin and adrenocorticotrophic hormone on renal function in man: An experimental model of inappropriate antidiuresis. The effect of prostaglandin synthesis inhibition on basal and ACTH-stimulated adrenal and renal function was investigated in normai volunteers. Data were collected during control and experimental study periods (13 days each). Adrenocorticotrophic hormone (Cosyntropin, 80 U/day) was administered i.v. on days 8 and 9 of each period. Indomethacin (150 mg/day) was given on days 5 through 13 of the experimental period. The subjects ate a constant diet containing 9 mEq of sodium, 100 mEq of potassium, and 2,500 ml of fluid daily. Indomethacin markedly inhibited urinary PGE excretion and plasma PGE concentration. The effect of ACTH alone as compared to the effect of ACTH and indomethacin showed: plasma sodium concentration, 139 ± 1 vs. 131 ± 3 mEg/liter (P < 0.01, mean ± SEM); plasma osmolality, 287 ± 3 vs. 270 ± 3 mOsm/liter (P < 0.01); free water clearance, 97 ± 66 vs. -1100 ± 380 ml/24hr (P < 0.01); urine volume, 2,000 ± 60 vs. 950 ± 200 ml/day (P < 0.01); and urine osmolality 282 ± 12 vs. 720 ± 144 mOsm/liter (P < 0.01). We conclude that the effects of ACTH and prostaglandin synthesis inhibition interact to result in inappropriate antidiuresis.Effet de l'indométhacine et de l'hormone adrénocorticotrope sur la fonction rénale chez l'homme: Un modèle expérimental d'antidiurèse inappropriée. L'effet de l'inhibition de la synthèse de prostaglandine sur la fonction surrénalienne basale et stimulée par l'ACTH et sur la fonction rénale a été étudié chez des sujets normaux volontaires. Les résultats ont été obtenus au cours de périodes contrôles et expérimentales de 13 jours chacune. De l'hormone adrénocorticotrope (Cosyntropin) a été administrée par voie i.v. les 8ème et 9ème jours de chaque période à raison de 80 U par jour. L'indométhacine, 150 mg/jour, a été donnée du 8ème au 13ème jour de la période expérimentale. Les sujets ont été soumis à un régime constant contenant 9 mEq de sodium, 100 mEq de potassium, et 2,500 ml de liquide par jour. L'indométhacine a fortement inhibé l'excrétion urinaire de PGE et abaissé la concentration plasmatique de PGE. L'effet de l'ACTH seul comparé à l'effet de l'ACTH associé à l'indométhacine a montré: une concentration plasmatique de sodium de 139 ± 1 vs. 131 ± 3 mEq/litre (P < 0,01) moyenne et SEM); une osmolalité plasmatique de 287 ± 3 vs. 270 ± 3 mOsm/litre (P < 0,01); une clearance de l'eau libre de 97 ± 66 vs. - 1100 ± 380 ml/24 hr (P < 0,01); un débit urinaire de 2,000 ± 60 vs. 950 ± 200 ml/jour (P < 0,01); et une osmolalité urinaire de 282 ± 12 vs. 720 ± 144 mOsm/litre (P < 0,01). Nous considérons que les effets de l'ACTH et de l'inhibition de la synthèse de prostaglandine se combinent pour déterminer une antidiurése inappropriée

Efficacy and Safety of Artemether in the Treatment of Chronic Fascioliasis in Egypt: Exploratory Phase-2 Trials

Fasciola hepatica and F. gigantica are two liver flukes that parasitize herbivorous large size mammals (e.g., sheep and cattle), as well as humans. A single drug is available to treat infections with Fasciola flukes, namely, triclabendazole. Recently, laboratory studies and clinical trials in sheep and humans suffering from acute fascioliasis have shown that artesunate and artemether (drugs that are widely used against malaria) also show activity against fascioliasis. Hence, we were motivated to assess the efficacy and safety of oral artemether in patients with chronic Fasciola infections. The study was carried out in Egypt and artemether administered according to two different malaria treatment regimens. Cure rates observed with 6×80 mg and 3×200 mg artemether were 35% and 6%, respectively. In addition, high efficacy was observed when triclabendazole, the current drug of choice against human fascioliasis, was administered to patients remaining Fasciola positive following artemether treatment. Concluding, monotherapy with artemether does not represent an alternative to triclabendazole against fascioliasis, but its role in combination chemotherapy regimen remains to be investigated

Skunk River Review Fall 2000, Vol 12

https://openspace.dmacc.edu/skunkriver/1020/thumbnail.jp