Introduction: Cardioactive steroids (CASs) are found in plants, animals, and insects. Their affinity for Na+-K+ ATPase is attenuated by the type of lactone at carbon 17 (C17) of the steroid backbone: those with 5-membered lactone rings, or cardenolides, are derived mostly from plants with 6-membered rings or from animals with bufadienolides. A systematic review of CAS poisoning was performed to compare the mortality rate of cardenolides and bufadienolides.Methods: MEDLINE was searched for articles using commonly reported names of CASs, and keywords were limited to human cases only. We searched cases from 1982 to 2003, so that supportive care was similar and digoxin-specific Fab was available. Identified reports of CAS poisoning were read to exclude cases involving licensed pharmaceuticals. Inclusion criteria included hyperkalemia, gastrointestinal symptoms, electrocardiographic evidence of CAS toxicity, digoxin serum concentration, or history of exposure to a substance containing a CAS. Clinical data was collected, including information about treatment with digoxin-specific Fab and treatment outcome.Results: Fifty-nine articles, describing 924 patients, were identified. Eight hundred ninety-seven patients (97%) ingested a CAS with a 5-membered lactone ring, and mortality was 6% (n = 54). Twenty-seven patients (2.9%) ingested a CAS with a 6-membered lactone ring, and mortality was 29.6% (n = 8). The difference in mortality rates was statistically significant (p < 0.001, [X 2 ]). CASs with 6-member rings accounted for the highest percentage of nonsuicidal exposures.Conclusion: Although cardenolides accounted for the majority of exposures, bufadienolides were five times more lethal than cardenolides.
The objective of this research was to develop a correlation between the runway condition rating (RCR) and runway surface friction measurements for dry and wet unpaved runways supporting C-17 aircraft operations. To achieve this objective, flight tests were conducted with an instrumented C-17 on several unpaved runways of different soil types under a variety of surface moisture conditions. A trailer-based continuous friction measurement device was used to conduct continuous surface friction measurements along the runway immediately before and following each C-17 landing event. These data were used to correlate the runway surface friction values from the device to the RCR computed from aircraft performance data. An accurate prediction of RCR allows predictions of aircraft stopping performance under adverse weather conditions.
Runway rubber removal is a maintenance function employed to ensure safe landing areas for aviation operations. Rubber deposits accumulate on runway areas where aircraft tires touchdown and braking occurs. This tire rubber build up occludes pavement microtexture and macrotexture, causing a significant loss in available skid resistance during wet conditions. Reduction of available pavement microtexture in a wet environment prevents the development of adhesional friction, which can result in viscous hydroplaning. Reduction of pavement macrotexture prevents the removal of bulk water from the tire-pavement contact area and also prevents the development of the hysteresis frictional component.To restore friction to safe levels for aircraft operations, rubber must be periodically removed. Several techniques for rubber removal are available. Waterblasting is a proven surface decontamination technique which employs the use of high or ultra-high pressure water (UHPW) to blast rubber deposits from the runway surface. This effort provides a performance-based comparison between three commercially available UHPW waterblasting systems. The evaluation was conducted on an ungrooved Portland Cement Concrete (PCC) runway with heavy rubber contamination along the touchdown and breaking zones. Several testing equipment such as Circular Track Meter (CTM) and Dynamic Friction Tester (DFT) were used to characterize the surface properties of the runway before and after rubber removal. The measurements were used for statistical pairwise comparative analysis of International Friction Index (IFI), speed constant and Mean Profile Depth (MPD). Treatment effect analysis of pre-measured and postmeasured data revealed that UHPW systems improved the surface texture properties by at least 40% regardless of the decontamination equipment.
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