Oxygen-enriched Atmosphere Research Articles

Reduction of paraquat toxicity by superoxide dismutase

The effect of intravenously administered superoxide dismutase on paraquat-treated rats kept either in air or an atmosphere of 90%–95% oxygen was investigated. Of those rats maintained in the oxygen-enriched atmosphere, 50% died within 30 hours whereas, 50 hours elapsed before 50% mortality was observed for the superoxide dismutase-treated rats. Those animals allowed to remain in air were more responsive to superoxide dismutase treatment. Of those animals for which paraquat was fatal, untreated rats showed 50% cumulative mortality within 35 hours after paraquat administration, whereas those rats treated with superoxide dismutase showed 50% mortality after 80 hours. Sections of lung tissue examined at low magnification indicated that the extensive alveolar and vascular damage caused by paraquat was ameliorated with the administration of superoxide dismutase. These findings may have particular relevance in the treatment of paraquat intoxication in humans.

Seed Dormancy Characteristics of Sideoats Gramagrass, Bouteloua curtipendula (Michx.) Torr.1

Seed sources of sideoats gramagrass [Bouteloua curtipendula (Michx.) Torr.] were accumulated from central and western United States, Mexico, and Argentina to evaluate duration and pattern of seed dormancy and to locate and identify dormancy conditioning factors of intact seed units (spikes of multiple spikelets). Dormant and nondormant seed sources were chosen for detailed investigations. Effects of time, removal of floral parts (glumes, lemmas, paleas, and awns), soil, leaching treatments, enriched oxygen atmosphere on germination, and potential inhibitors of seed units on germination of seed were studied. Postharvest dormancy was present in seed units of all sources, but disappeared after 4 to 6 months of dry storage after harvest. Postharvest dormancy was conditioned by nature of the caryopses. Long‐term dormancy persisted in seed units for 5 years in dormant sources without viability change. Long‐term dormancy was broken when floral parts were removed from caryopses. Placing seed units in soil, in enriched oxygen atmosphere, and in sodium hypochlorite was effective in breaking dormancy. The mechanism of longterm dormancy of sideoats gramagrass seed units involved interactions among the following factors: light weight of caryopses, impermeable floral parts of caryopses, and presence of coumarin‐like inhibitory compounds. Association of dormancy with establishment under stress environments of grasslands is to be determined. Results of this investigation offer approaches to select and characterize germplasm with dormancy qualities that may be favorable to establishment.

Lunar simulation.

The purpose of this study was to examine the combined effects of simulated lunar environmental variables on human performance. A facility was developed to simulate the following aspects of the astronaut's lunar environment: confinement within a lunar shelter habitat with an oxygen-enriched atmosphere, high-risk vacuum, ⅙ g., lunar “terrain” characteristics, and space suit encumbrances. Four subjects were confined for five days in a simulated lunar shelter. During the fourth and fifth days, two subjects each made two simulated sorties outside the shelter. Basic maintenance and control tasks were performed under ⅙ g.; pressurized space suit conditions were at chamber altitudes at 18,000 and 100,000 ft., respectively. Results of this testing at altitude were compared with baseline measures conducted under ambient sea level conditions. It was concluded that the combined effect of the simulated lunar environment variables can substantially degrade certain categories of astronaut performance. The reduced pressure of altitude as well as ⅙ g. and space suit encumbrances appear to be significant factors affecting man's performance.

Dangers due to increased flammability of materials in oxygen-enriched atmospheres

Examines cases of oxygen-enriched accidents, causes of ignition, and safety considerations.

Rehabilitation of patients with obstructive pulmonary diseases. The role of enriched oxygen.

The conclusion may be drawn that rehabilitative measures for obstructive pulmonary diseases are better tolerated in an oxygen-enriched atmosphere. No ill effects have been observed. An increase of 4 to 10 per cent in the oxygen concentration of the atmosphere appears to be sufficient to maintain approximately normal arterial oxygen saturation.

Breathing Training in Pulmonary Emphysema

<h3>To the Editor:—</h3> In the paper by R. V. Ebert and J. A. Pierce, "Therapy in Chronic Bronchitis and Pulmonary Emphysema" (<i>JAMA</i><b>184</b>:490 [May 11] 1963), this statement appears: "Some physicians achieve considerable improvement in the patient's symptoms by the use of breathing exercises, but whether or not the favorable effect is entirely psychogenic is unclear." Therapeutic efforts to overcome the disorganized breathing pattern of these breathless subjects occupies an extensive literature. I shall refer briefly to several recent reports. In 1954 I mentioned that significant rehabilitation of several hundred patients with pulmonary emphysema was induced by a breathing training program; the additional use of graded exercise during the inhalation of oxygen-enriched atmospheres was described as a method of increasing the capacity for exercise in patients handicapped by excessive inactivity.¹An editorial inThe Journalcalled attention to the latter development in 1961.² I would like to

Unusual Corrosion Growth Products Formed on Copper

An electron transmission study was made of the corrosion growth products formed on preworked and preannealed copper at various temperatures in environments of water vapor saturated air and oxygenated water vapor saturated air. Unusual blade-type growths were obtained only on the preworked specimens exposed to water vapor saturated air and within a narrow critical temperature range. These results indicate that blade-type formations are a unique transition growth phenomenon dependent to a large extent on the presence of the water vapor and the stresses induced during preworking. Oxygen enrichment of the reacting atmosphere accentuated whisker-type growths for both the preworked and preannealed samples. At some temperatures in the oxygen enriched water vapor atmosphere the preannealed samples exhibited increasd growth over that typified by the preworked samples. In some cases whiskers with bulbous masses at the tips were observed, suggesting melting at the tips from the heat generated by the electron beam. 3.4.3, 6.3.6

Studies on the Effects of Adding Carbon Dioxide to Oxygen-enriched Atmospheres in Low Pressure Chambers

Studies on the Effects of Adding Carbon Dioxide to Oxygen-enriched Atmospheres in Low Pressure Chambers

Carbon black from natural gas

Based on an analysis of fires in the oxygen-enriched atmosphere conditions in spacecraft and other sealed chambers of various purposes, the most dangerous groups of fires are identified. For this purpose, groups were compiled to analyze dependences that describe the increase of fire hazard to a critical value.A criterion for determining timely and effective fire extinguishing was offered. Fire experiments in oxygen-enriched atmosphere conditions were conducted, and an array of experimental data on the mass burning rate of materials and their extinguishing by water mist was obtained.Relationships colligating an array of experimental data were offered. Experimental and analytical studies were taken as a basis for hand fire extinguisher implementation for manned spacecraft.