Advanced Water Recovery Technologies for Long Duration Space Exploration Missions

Extended-duration space travel and habitation require recovering water from wastewater generated in spacecrafts and extraterrestrial outposts since the largest consumable for human life support is water. Many wastewater treatment technologies used for terrestrial applications are adoptable to extraterrestrial situations but challenges remain as constraints of space flights and habitation impose severe limitations of these technologies. Membrane-based technologies, particularly membrane filtration, have been widely studied by NASA and NASA-funded research groups for possible applications in space wastewater treatment. The advantages of membrane filtration are apparent: it is energy-efficient and compact, needs little consumable other than replacement membranes and cleaning agents, and doesn't involve multiphase flow, which is big plus for operations under microgravity environment. However, membrane lifespan and performance are affected by the phenomena of concentration polarization and membrane fouling. This article attempts to survey current status of membrane technologies related to wastewater treatment and desalination in the context of space exploration and quantify them in terms of readiness level for space exploration. This paper also makes specific recommendations and predictions on how scientist and engineers involving designing, testing, and developing space-certified membrane-based advanced water recovery technologies can improve the likelihood of successful development of an effective regenerative human life support system for long-duration space missions

The food safety impact of salt and sodium reduction initiatives

Excessive or high salt or sodium intake is known to cause hypertension and other diseases. Within the United Kingdom voluntary targets for salt reduction have been set and laid out in the Secretary of State responsibility deal. This review considers the options available to food manufacturers to enable them to reduce salt and the potential food safety risks associated with those options. Gaps in research and knowledge within the areas of information supplied to food manufacturers, alternative solutions for salt replacement and the food safety impact of salt reduction are discussed

L6 skeletal muscle cells have functional V1-vasopressin receptors coupled to stimulated inositol phospholipid metabolism

AbstractThe effects of vasopressin and related peptides upon the rat skeletal muscle cell line, L6, have been examined. No effects upon cellular cyclic AMP levels were found indicating that L6 cells possess no functional V2-vasopressin receptors. Vasopressin and its analogues did, however, stimulate the rapid and dose-dependent accumulation of inositol phosphates. This effect and the rank order of potency of vasopressin analogues demonstrate the presence of functional V1-vasopressin receptors upon L6 cells. These results suggest that the L6 line may be a useful model for vasopressin effects upon skeletal muscle metabolism

Axial Subsynchronous Vibration

LectureSevere axial subsynchronous vibrations (SSV) can be encountered in turbomachinery. A major concern is the potential for danger from the high levels of vibration acting on the rotor. Longer term implications are fretting and fatigue damage of the rotor components and support structures, which include the thrust bearing pivot contact areas. Although axial SSV is a concern in turbomachinery applications, little published literature can be found on the subject. A series of laboratory tests were therefore designed and performed to investigate the phenomenon in more detail. This paper presents experimental data from a series of pivoted shoe thrust bearing tests investigating the influence of operating conditions and other parameters on axial SSV. Parameters include thrust load, shaft speed, oil flow, inlet temperature, axial clearance, pivot offset, and direct and flooded lubrication. Test results are used to evaluate techniques that have been used when attempting to resolve axial vibration issues. Additional data from thrust shoe load cells and thrust shoe proximity probes provide unique and valuable insight that allowed development of a more robust solution

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Profiled Leading Edge Groove Tilting Pad Journal Bearing For Light Load Operation.

LecturePg. 1-16Optimization of a leading edge groove tilting pad journal bearing for application in a small, high speed, multistage steam turbine is described. Rotordynamics constraints to meet a design objective maximum operating speed of 1 8000 rpm resulted in a rotor with a 51.0 in bearing span and 5.0 in diameter tilting pad journal bearings. This configuration yielded a design with projected bearing loads of less than 25 psi, and journal surface speeds that could approach 400 ft/sec. Under these conditions, the applicable limits of conventional style tilting pad journal bearings are stretched, since operation is well into the turbulent flow regime. This can result in significantly higher than predicted operating pad temperatures and increased frictional losses. Furthermore, at very light pad loads, bearing dynamic performance and influence on rotor behavior often does not correlate well with theory. For this application, high efficiency leading edge groove bearings (journal and thrust) were used, due to their preferred steady state operating characteristics at high speed. However, as is often observed with lightly loaded conventional style journal bearings, dynamic performance did not precisely match that predicted by theory. This was investigated by profiling the exit side of the leading edge groove with both a tapered and pocket geometry. Two case histories are presented demonstrating their effect on rotor-bearing stability and unbalance response. The modified bearings yielded greater system stability at high speeds, reduced overall vibration amplitudes, and greatly improved effective damping on passing through the rotor's first peak response speed

The Socioeconomic Determinants of HIV/AIDS Infection Rates in Lesotho, Malawi, Swaziland and Zimbabwe

This paper uses data from the Demographic and Health Survey to analyze the relationship between HIV status and the socioeconomic and demographic characteristics of adults in Lesotho, Malawi, Swaziland and Zimbabwe. We construct the HIV/AIDS risk profile of the average adult, compute the values of age, education and wealth where the estimated probability of infection assumes its highest value, and we determine the percentage of adults for which age, education and wealth are positively correlated with the probability of infection. We find that in all the four countries: (i) the probability of being HIV positive is higher for women than for men; (ii) the likelihood of infection is higher for urban residents than for rural residents; and (iii) there is an inverted-U relationship between age and HIV status. We also find that unlike gender, rural/urban residence and age, the relationship between the probability of HIV infection and wealth, education and marital status varies by country. Our results provide support for country specific and more targeted HIV policies and programs

Interactive effects of dietary protein/lipid level and oil source on growth, feed utilisation and nutrient and fatty acid digestibility of Atlantic salmon

Although the use of fish meal (FM) and fish oil (FO) has been extensive in Atlantic salmon culture, there is a growing need for less reliance on these commodities. Moreover, it is crucial for the aquafeed industry to optimise the use of dietary protein and to improve the protein utilisation in salmon diets. The interactive effects of the dietary protein/lipid level and rapeseed oil (RO) inclusion on growth, feed utilisation, nutrient and fatty acid (FA) digestibility and whole body chemical composition of large Atlantic salmon (Salmo salar L.), reared at summer water temperatures (11.6 °C), were investigated in a ten week feeding trial. The fish (initial weight 2053 g) were fed six isoenergetic diets in a factorial design containing 350 g kg−1/350 g, kg−1, 330 g kg−1/360 g kg−1, 290 g kg−1/380 g kg−1 of protein/lipid for high protein (HP), medium protein (MP) and low protein (LP) diets, respectively. At all protein/lipid levels the oil source was either FO or RO (60% of the added oil). At the end of the trial the final weights ranged from 3340–3664 g and the FCR from 0.99– 1.10. The protein level did not affect significantly any of the growth parameters but the oil source had a significant effect on final weight, specific growth rate (SGR) and thermal growth coefficient (TGC), showing improved growth with RO inclusion. This could be explained by the significantly higher lipid digestibility of the fish fed the diets containing RO (86.1 vs. 92.2%) which was probably affected by the diet FA composition; the apparent digestibility coefficient (ADC) of saturated FA, and to a lesser extent of unsaturated FA and especially monoenes, was improved by RO inclusion. The protein ADC was significantly affected by the protein level indicating a higher ADC for the HP diets compared to the LP (80.1 vs. 77.7%, respectively). Regarding the whole body composition, moisture was significantly affected by both factors, the fat content was significantly affected only by the oil source, while significant interactions were shown for the protein content. In conclusion, the results of this study suggest that low protein/high lipid diets can be used with no negative effects on the growth, FCR and chemical composition of Atlantic salmon reared at high water temperatures. Moreover, the replacement of FO with RO can enhance the growth of the fish as well as the nutrient and FA digestibility of the diets

Effects of dietary protein and fat level and rapeseed oil on growth and tissue fatty acid composition and metabolism in Atlantic salmon (Salmo salar L.) reared at low water temperatures

A 12 week feeding trial was conducted to elucidate the interactive effects of dietary fat and protein contents and oil source on growth, fatty acid composition, protein retention efficiency (PRE) and β-oxidation activity of muscle and liver in Atlantic salmon (Salmo salar L.) at low water temperatures (4.2 oC). Triplicate groups of Atlantic salmon (initial weight 1168 g) were fed six isoenergetic diets formulated to provide either 390 g kg-1 protein and 320 g kg-1 fat (high protein (HP) diets) or 340 g kg-1 protein and 360 g kg-1 fat (low protein (LP) diets); within each dietary protein/fat level crude RO comprised 0, 30 or 60% (R0, R30, R60, respectively) of the added oil. After 12 weeks the overall growth and FCR were very good for all treatments (TGC; 4.76 (±0.23), FCR; 0.85 (±0.02)). Significant effects were shown due to oil source on SGR and TGC only. The liver and muscle FA compositions were highly affected by the graded inclusion of RO. The PRE was significantly affected by the dietary protein level, while no significant effects were shown in total β-oxidation capacity of liver and muscle. The results of this study suggest that more sustainable, lower protein diets with moderate RO inclusion can be used in Atlantic salmon culture at low water temperatures with no negative effects on growth and feed conversion, no major detrimental effects on lipid and fatty acid metabolism and a positive effect on protein sparing