SEARCH · Engineering Papers
Results for “dehydration”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Meat-type food development and experiences
Dehydrated and rehydratable meat-type foods for space flight feeding
Feeding man in space
Semi-solid, dehydrated, rehydratable, thermally stabilized wet, and intermediate moisture food development for space flights
Development of non-cream style soups Final report
Noncream style dehydrated soups for use in Apollo feeding system
Effect of environmental temperature on the toxicity of caffeine and dextroamphetamine in mice
Mild temperature and dehydration effects on toxicity of caffeine and dextroamphetamine in mice
Modification of physical properties of freeze-dried rice
Freeze cycling process consists of alternately freezing and thawing precooked rice for two cycles, rice is then frozen and freeze-dehydrated in vacuum sufficient to remove water from rice by sublimitation. Process modifies rice grain structure and porosity, enabling complete rehydration in one minute in hot water.
A re-examination of the stability of goethite on Mars
Goethite stability on Mars, considering dehydration-rehydration cycle and time average atmospheric water vapor content
Effect of the method of process on the control of microbial growth by water activity in foods
Two methods for preparation of intermediate moisture foods (IMF) were investigated; water absorption and water desorption technique. Results indicate that shelf stability of IMF systems might be enhanced by preparing foods by rehumidifying dehydrated foods to optimum water activity rather than drying food to reduce the water activity.
Effect of surface moisture on dielectric behavior of ultrafine BaTiO3 particulates.
The effects of adsorbed H2O on the dielectric properties of ultrafine BaTiO3 particulates of varying particle size and environmental history were determined. The dielectric behavior depends strongly on surface hydration. No particle size dependence of dielectric constant was found for dehydroxylated surfaces in ultrafine particulate (unsintered) BaTiO3 materials. For equivalent particle sizes, the ac conductivity is sensitive to surface morphology. Reactions with H2O vapor appear to account for the variations in dielectric properties. Surface dehydration was effectively accomplished by washing as-received powders in isopropanol.
Passenger fluid volumes measured before and after a prolonged commercial jet flight.
Interstitial and intracellular fluid volumes were calculated from measured plasma volume, extracellular volume and total body water of six subjects before and after a 24-hour commercial overseas flight. No change occurred in these spaces or in peripheral hematocrit or total serum protein concentration. The subjective feeling of dehydration and the actual swelling of the lower extremities characteristically found among passengers at the end of a long trip of this type seems to represent a shift in body fluids to the dependent portions of the body rather than water retention or a decrease in the intravascular water volume.
Embryogenesis in 100% O2 at reduced pressure.
Fertile chicken eggs were incubated in an altitude chamber in a near 100% O2 atmosphere at 225 torr. Both N2 and CO2 were kept under 0.5%. Temperature was a standard 37.5 C but a high relative humidity of 90% was required to prevent dehydration. In ten trials involving 382 eggs, hatchability averaged 21% of controls and weight of chicks was 11% less than controls, but embryo mortality was distributed similarly. Low pressure per se and small differences in O2 tension may have affected the results, but similarities to incubation in 21% O2-79% He call attention to absence of nitrogen as a possible explanation.
Urinary Excretion of Antidiuretic Hormone in Man
It is shown that urinary excretion of ADH can be detected readily and quantitated accurately. The ADH excretion in normal subjects is inhibited following the administration of a water load and stimulated following water deprivation. It appears that measurement of ADH excretion in man provides a means of quantitating alterations in neurohypophyseal ADH secretion. By determining not only the basal excretion of ADH but also the response to such physiological influences as water loading and dehydration, it becomes possible to study the dynamics of ADH release. Thus, the ability to extract ADH efficiently from urine combined with a sensitive and specific technique for determination of ADH concentration allows the exploration of regulatory systems for ADH control in the normal state as well as the etiological role of altered ADH secretion in clinical disorders of water balance.
Polymerization of amino acids under primitive earth conditions.
Small amounts of peptides were obtained when equal amounts of methane and ammonia were reacted with vaporized aqueous solutions of C14-labeled glycine, L-alanine, L-aspartic acid, L-glutamic acid and L-threonine in the presence of a continuous spark discharge in a 24-hr cyclic process. The experiment was designed to demonstrate the possibility of peptide synthesis under simulated primeval earth conditions. It is theorized that some dehydration-condensation processes may have taken place, with ammonium cyanide, the hydrogencyanide tetramer or aminonitriles as intermediate products, during the early chemical evolution of the earth.
Organosilicon compounds. XVIII - Silicon-containing dianhydrides
Description of four new silicon-containing dianhydrides synthetized in an attempt to provide useful silicon-containing polyimide precursors. They were prepared by aqueous potassium permanganate-pyridine oxidations of corresponding tetramethyl intermediates to form tetracarboxylic acids, which were dehydrated to the dianhydrides.
Dichromated-gelatin hologram process for improved optical quality
Optical distortions are eliminated by use of wetting agency followed by sequential immersion in several alcohol-water baths of increasing alcohol concentration. Dehydration proceeds uniformly over surface of gelatin. Dried plate is free of optically-distorting thickness variations.
Means and methods of physical conditioning of man in long space flights
Methods of prophylaxis for disorders caused predominantly by reduction or absence of hydrostatic blood pressure in weightlessness and in experimental stimulation of it (readjustment of the watersalt metabolism, relative dehydration, disruption of competence of the cardiovascular system with respect to orthostatic loads, etc.), are adequately substantiated. Two theoretically possible approaches to prophylaxis of this type of disorder are examined: The use of methods of simulation of the effect of hydrostatic blood pressure in flight and the decrease in the gravitational redistribution of blood to the lower part of the body in the postflight period. In particular, the method of negative pressure in the lower region of the body gave favorable results. A significant decrease in orthostatic disorders after completion of such experiments was achieved by use of g-suits or other types of special clothing.
Differential permeation of artemia cysts and cucumber seeds by alcohols
The rate of penetration of the simpler alcohols into brine shrimp cysts and cucumber seeds was studied. In solutions below 70% the rate of penetration is related to lipid solvent capacity of the alcohol. In concentrations above 70%, particularly in absolute alcohols, methanol penetrates brine shrimp rapidly and ethanol penetrates slowly. All the other alcohols tested did not penetrate the dormant structures. Ethionine and deuteroxy-methanol did not affect the rate of penetration of methanol. It is suggested that in dehydrated membranes the lipid moiety is protected by a continuous sheet of protein. Methanol, which is fairly similar to water, is probably able to penetrate the membrane by initiating a conformation change in the protein, exposing the lipid which subsequently dissolves in the methanol thus destroying the membrane.
Fluid shifts during thermal stress with and without fluid replacement
Six unacclimatized men rested for 4 hr in a hot, dry environment without fluid replacement (DH). Another group of six men were exposed to the same thermal stress, replacing evaporative fluid loss with warm 0.1% NaCl solution (FRP). Total grams of circulating hemoglobin, determined by CO immediately prior to and again during the last minutes of heat exposure, increased an insignificant 1.6 and 1.3% during DH and FRP, respectively. With DH, body weight loss of 2.6% was accompanied by a 7.8% reduction in calculated plasma volume (PV). Even when body weight was maintained (FRP), PV decreased 2.9% during the heat exposure. Total circulating serum protein did not change as a result of the heat stress with either DH or FRP. In a test-retest series of experiments on four men, DH was not detrimental to sweat rate. It is shown that hemodilution is not a general response to acute heat exposure. The disproportionately large reduction in PV during thermal dehydration is confirmed.