Liquid droplet radiator program at the NASA Lewis Research Center

The NASA Lewis Research Center and the Air Force Rocket Propulsion Laboratory (AFRPL) are jointly engaged in a program for technical assessment of the Liquid Droplet Radiator (LDR) concept as an advanced high performance heat ejection component for future space missions. NASA Lewis has responsibility for the technology needed for the droplet generator, for working fluid qualification, and for investigating the physics of droplets in space; NASA Lewis is also conducting systems/mission analyses for potential LDR applications with candidate space power systems. For the droplet generator technology task, both micro-orifice fabrication techniques and droplet stream formation processes have been experimentally investigated. High quality micro-orifices (to 50 micron diameter) are routinely fabricated with automated equipment. Droplet formation studies have established operating boundaries for the generation of controlled and uniform droplet streams. A test rig is currently being installed for the experimental verification, under simulated space conditions, of droplet radiation heat transfer performance analyses and the determination of the effect radiative emissivity of multiple droplet streams. Initial testing has begun in the NASA Lewis Zero-Gravity Facility for investigating droplet stream behavior in microgravity conditions. This includes the effect of orifice wetting on jet dynamics and droplet formation. Results for both Brayton and Stirling power cycles have identified favorable mass and size comparisons of the LDR with conventional radiator concepts

The Wyoming carbon underground storage project: Geologic characterization of the Moxa Arch and Rock Springs Uplift

AbstractThe state of Wyoming, in the northwestern United States, produces 40% of the nation’s coal, most of which is transported out of the state. The remainder is used at power plants within Wyoming to generate approximately 7% of U.S. electricity. Carbon capture and storage from these power stations could significantly reduce U.S. carbon emissions. Wyoming statutes and rules proposed by the U.S. Environmental Protection Agency and Wyoming Department of Environmental Quality regarding subsurface carbon storage require that CO2 injection must not affect established or potential drinking water aquifers, oil and gas fields, or other mineral estates. Wyoming has several potential large-scale geologic carbon storage reservoirs that meet these criteria, in the form of saline aquifers in regional basins and uplifts. The Wyoming Carbon Underground Storage Project has recently been funded by the U.S. Department of Energy and the state of Wyoming to 1) assess the CO2 storage potential of two possible locations in southwestern Wyoming: The Moxa Arch and the Rock Springs Uplift, 2) develop a system for displaced fluid management, 3) plan monitoring and verification activities, and 4) design infrastructure in preparation for geologic carbon sequestration. The Wyoming Carbon Underground Storage Project represents collaboration between the University of Wyoming, the Wyoming State Geologic Survey, ExxonMobil Corporation, Los Alamos National Laboratory, and Baker Hughes Incorporated. The authors are involved primarily in the geologic stratigraphic and structural characterization of the Moxa Arch and Rock Springs Uplift.The Moxa Arch is an anticline that trends from the Uinta Mountains, 200 km north-northwest to the eastern front of the Wyoming fold-and-thrust belt. Potential storage reservoirs on this large geologic structure include the Jurassic Nugget Sandstone, the Mississippian Madison Limestone, and the Ordovician Bighorn Dolomite. The Nugget Sandstone is a heterogeneous and anisotropic eolian deposit that has been extensively exploited for oil and gas at certain locations on the Moxa Arch, which complicates its usage as a repository for carbon dioxide. The Madison Limestone is a proven storage reservoir; ExxonMobil has been injecting CO2 (up to 25 MMCFD) and H2S (up to 65 MMCFD) into the Madison Limestone on the Moxa Arch for seven years at the Shute Creek Gas Plant. The Bighorn Dolomite is stratigraphically complex with large variations in porosity and permeability due to primary burrowing and repeated dolomitization and dedolomitization. Depending on location on the anticline, the Nugget Sandstone lies 3 to 6.5 km below the surface (-1 to -4.5 km subsea), and the Bighorn Dolomite and Madison Limestone range from 4.5 to 8 km below the surface (-2.5 to -6 km subsea).The Moxa Arch is structurally uncomplicated; it is a basement-involved anticline formed by a west-vergent Late Cretaceous-age thrust fault, with gently-dipping limbs (0 to 5 degrees). Leakage risk is extremely low because impermeable evaporite (anhydrite) intervals overly the potential reservoirs, and preliminary interpretation of seismic data reveal that few faults exist other than the main thrust. The Naughton Power Plant, a 707 MW coal-fired power station emitting up to 6 Mt of CO2 per year, lies 30 km west of the crest of the anticline.The Rock Springs Uplift, 100 km east of the Moxa Arch, extends 80 km north from the Wyoming-Utah border. The target storage reservoirs are the Pennsylvanian Weber Sandstone (correlative to the Tensleep Sandstone) and the Mississippian Madison Limestone. The Weber Sandstone exhibits wide variations in reservoir properties (porosity and permeability) due to dune/interdune/intradune facies changes, and appears to have experienced local secondary diagenesis that further reduced porosity. The Madison Limestone is expected to have similar reservoir properties to its lithologic correlative on the Moxa Arch. The Weber Sandstone and Madison Limestone range in depth from 2 to 6 km below the surface (0.3 to -4.5 km subsea), depending on location on the anticline.The Rock Springs Uplift offers challenges for structural analysis. Like the Moxa Arch, the Uplift was formed by a Late Cretaceous-age west-vergent basement-involved reverse fault, but the limbs of the fold are at steeper dips (approximately 15 degrees on the west limb, shallower on the east limb), and these limbs are cut at depth by additional reverse faults. In a hydrocarbon field on the southeastern flank of the uplift there is a possibility that condensate is migrating from the Weber Sandstone along one of these reverse faults, suggesting that the trap is breached. In addition, a series of east-west trending normal faults cut Cretaceous shales at the surface, possibly with throws that exceed the thickness of the uppermost regional seal. It is necessary to determine if these east-west faults also compromise the Triassic units that could provide a seal above the Weber Sandstone. The Jim Bridger Power Plant (coal-fired) is located on the east flank of the Rock Springs Uplift; it has 2200 MW capacity and emits up to 18 Mt of CO2 per year.Future U.S. energy demands will draw heavily on Wyoming’s coal-fired power plants, and the state is taking steps to sequester the produced carbon. Wyoming hosts several large geologic traps that if properly risked and evaluated have promise as long-term, stable repositories for anthropogenic carbon dioxide. Based upon our preliminary assessment of the multiple clastic and carbonate receiving formations in the Moxa Arch and Rock Springs Uplift, and the experience of successful injection at ExxonMobil’s Shute Creek Gas Plant, these geologic structures in southwestern Wyoming are among the most promising large CO2 geologic storage sites in the United States

Effects of alcohol consumption on mortality in patients with Type 2 diabetes mellitus

Aims/hypothesis: Moderate alcohol intake has been associated with increased life expectancy due to reduced mortality from cardiovascular disease. We prospectively examined the effects of alcohol consumption on mortality in Type 2 diabetic patients in Switzerland. Methods: A total of 287 patients with Type 2 diabetes mellitus (125 women, 162 men), recruited in Switzerland for the WHO Multinational Study of Vascular Disease in Diabetes, were included in this study. After a follow-up period of 12.6±0.6 years (means ± SD), mortality from CHD and from all causes was assessed. Results: During the follow-up, 70 deaths occurred (21 from CHD, 49 from other causes). Compared with non-drinkers, alcohol consumers who drank alcohol 1 to 15g, 16 to 30g and 30g or more per day had the following risk rates of death from CHD: 0.87 (95% CI: 0.25 to 2.51, NS), 0.00 (95% CI: 0.00 to 0.92, p less than 0.05) and 0.37 (95% CI, 0.01 to 2.42, NS), respectively. The corresponding risk rates of death from all causes were 1.27 (95% CI: 0.68 to 2.28, NS), 0.36 (95% CI: 0.09 to 0.99, p less than 0.05) and 1.66 (95% CI: 0.76 to 3.33, NS). Conclusions/interpretation: In Swiss Type 2 diabetic patients moderate alcohol consumption of 16 to 30g per day was associated with reduced mortality from CHD and from all causes. Alcohol intake above 30g per day was associated with a tendency towards increased all-cause mortalit

Metabolic and hormonal studies of Type 1 (insulin-dependent) diabetic patients after successful pancreas and kidney transplantation

Long-term normalization of glucose metabolism is necessary to prevent or ameliorate diabetic complications. Although pancreatic grafting is able to restore normal blood glucose and glycated haemoglobin, the degree of normalization of the deranged diabetic metabolism after pancreas transplantation is still questionable. Consequently glucose, insulin, C-peptide, glucagon, and pancreatic polypeptide responses to oral glucose and i.v. arginine were measured in 36 Type 1 (insulin-dependent) diabetic recipients of pancreas and kidney allografts and compared to ten healthy control subjects. Despite normal HbA1 (7.2±0.2%; normal <8%) glucose disposal was normal only in 44% and impaired in 56% of the graft recipients. Normalization of glucose tolerance was achieved at the expense of hyperinsulinaemia in 52% of the subjects. C-peptide and glucagon were normal, while pancreatic polypeptide was significantly higher in the graft recipients. Intravenous glucose tolerance (n=21) was normal in 67% and borderline in 23%. Biphasic insulin release was seen in patients with normal glucose tolerance. Glucose tolerance did not deteriorate up to 7 years post-transplant. In addition, stress hormone release (cortisol, growth hormone, prolactin, glucagon, catecholamines) to insulin-induced hypoglycaemia was examined in 20 graft recipients and compared to eight healthy subjects. Reduced blood glucose decline indicates insulin resistance, but glucose recovery was normal, despite markedly reduced catecholamine and glucagon release. These data demonstrate the effectiveness of pancreatic grafting in normalizing glucose metabolism, although hyperinsulinaemia and deranged counterregulatory hormone response are observed frequently

Methane and nitrous oxide fluxes across an elevation gradient in the tropical Peruvian Andes

Peer reviewedPublisher PD

QTc interval and resting heart rate as long-term predictors of mortality in type 1 and type 2 diabetes mellitus: a 23-year follow-up

Aims/hypothesis: We evaluated the association of QT interval corrected for heart rate (QTc) and resting heart rate (rHR) with mortality (all-causes, cardiovascular, cardiac, and ischaemic heart disease) in subjects with type 1 and type 2 diabetes. Methods: We followed 523 diabetic patients (221 with type 1 diabetes, 302 with type 2 diabetes) who were recruited between 1974 and 1977 in Switzerland for the WHO Multinational Study of Vascular Disease in Diabetes. Duration of follow-up was 22.6 ± 0.6years. Causes of death were obtained from death certificates, hospital records, post-mortem reports, and additional information given by treating physicians. Results: In subjects with type 1 diabetes QTc, but not rHR, was associated with an increased risk of: (1) all-cause mortality (hazard ratio [HR] 1.10 per 10ms increase in QTc, 95% CI 1.02-1.20, p = 0.011); (2) mortality due to cardiovascular (HR 1.15, 1.02-1.31, p = 0.024); and (3) mortality due to cardiac disease (HR 1.19, 1.03-1.36, p = 0.016). Findings for subjects with type 2 diabetes were different: rHR, but not QTc was associated with mortality due to: (1) all causes (HR 1.31 per 10 beats per min, 95% CI 1.15-1.50, p < 0.001); (2) cardiovascular disease (HR 1.43, 1.18-1.73, p < 0.001); (3) cardiac disease (HR 1.45, 1.19-1.76, p < 0.001); and (4) ischaemic heart disease (HR 1.52, 1.21-1.90, p < 0.001). Effect modification of QTc by type 1 and rHR by type 2 diabetes was statistically significant (p < 0.05 for all terms of interaction). Conclusions/interpretation: QTc is associated with long-term mortality in subjects with type 1 diabetes, whereas rHR is related to increased mortality risk in subjects with type 2 diabete