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Seasonal fluctuations of the physicochemical conditions were recorded from five temporary ponds in the New Forest, over a period of two years. Diurnal fluctuations were also recorded. Physicochemical factors studied were pond volume; air, water and substratum temperature; water pH; water conductivity; and water dissolved oxygen level. The observed patterns of fluctuation are discussed and a concept of pond stability, to which the fluctuations may be related, is advanced.

The method of NADH oxidation-reduction state microfluorometry has been applied to the surface of the rat brain in an attempt to record a two-dimensional picture of NADH fluorescence in normoxia, with the animal breathing 20% oxygen, and to determine the extent and location of fluorescence intensity changes in hypoxia caused by lowering inspired oxygen level to 2%. The 50 μm beam of a microfluorometer was scanned in parallel lines 250 μm apart over the cerebrocortical surface, dura intact. Chart records of corrected fluorescence, or 366 nm reflected light substracted from 450 nm fluorescence emission in a 1:1 ratio, were digitized and the resulting data utilized by a computer to produce ‘three-dimensional’ plots of normoxic and hypoxic fluorescence and the difference between them. Heterogeneities were noted in the distribution of fluorescence over the cortex in normoxia. Non-uniformity of changes in local fluorescence magnitude with hypoxia was also observed.

SummaryDaughter sporocysts of S. mansoni cultured axenically in the presence of sulfhydryl compounds in a controlled gas environment underwent growth and development, in some cases culminating in the production of a new generation of daughter sporocysts. The effect occurred within a narrow range of concentrations of either dithiothreitol or a combination of cysteine and glutathione, together with lowering the oxygen level, but not when sulfhydryl or decreased oxygen were used alone. Sporocyst development was equivalent to that obtained monoxenically in association with cell cultures and greater than occurred in medium conditioned by cell cultures.

Changes in the serum protein, as shown by electrophoretic analyses, appear to be correlated with changes in the environment of the organism. These changes may be associated with aquatic pollution. A diurnal oxygen pulse of 3 ppm for 8 hours per day for 9 days produced a significant stress pattern in the serum protein fractions of bluegills and largemouth bass, but did not change that of yellow bullheads. According to this study, the minimum oxygen level (for 8 hours) that will not adversely affect bluegills and largemouth bass is well above the generally proposed 3 ppm.

Rectal temperature in man is a function of various conditions (e.g. time of day, ambient temperature, work load, oxygen level), whose effects interact with each other in a manner so far mostly unknown. Therefore, it would be desirable not only to make measurements of rectal temperature with these conditions changed separately but also long time recordings under extreme conditions in the field. In order to facilitate this, small battery operated thermographs (90×70×30 mm; 350 g), with small thermistor probes, were developed which allow continuous recording of rectal temperature under extreme environmental conditions without inconvenience to the subjects. Precision in temperature is better than 0.1°C; precision in time after recordings of many weeks duration (with weekly changes of the recording disc) is better than 0.5 h. An exemplum is shown demonstrating the diurnal course of rectal temperature averaged over 1 week, recorded during a mountain climbing expedition to heights of 5000–7000 m, with temperatures between +20°C and −20°C.

T here have been many discussions on the optimum flow rate of blood during total cardiopulmonary bypass.1 It is generally accepted that the optimum flow rate is that which supplies the patient with a required amount of oxygen so that the venous oxygen level is adequately maintained.2,3 However, no attempt seems to have been made to determine the optimum flow rate from a standpoint of circulatory dynamics as was done in the present study.

SummaryFruit stored in polyethylene case liners develops a modified storage atmosphere which may prolong the storage life of the fruit. The physical principles underlying the production of these atmospheres axe discussed and it is shown that the very variable oxygen level in these atmospheres, which has been reported by a number of workers, is an inherent feature of this storage technique.

Summary In the present study we have attempted to relate level of blood oxygen to the state of the infant at or near the time of birth. Oxygen levels were correlated to clinical ratings of anoxia and to performance on the Behavior-Tests for the Newborn. A low but significant relationship between cord oxygen and clinically observed anoxia was found. There was, however, no relationship between immediate postnatal anoxia and oxygen level at one hour. There was essentially no relationship between oxygen and performance on behavioral tests made when the infants were from 24 to 48 hours of age, although we have found previously that there is a relationship between these tests and the seriousness of the clinical condition. Also, there was no difference in performance on Behavior Tests between extreme groups selected on the basis of oxygen levels. Groups selected because of low cord oxygen or low oxygen throughout the first hour of life did not perform in a manner that was significantly different from groups whose oxygen readings were exceptionally high. The one exception to this was in the reverse direction from what would have been predicted; i.e., the low oxygen group performed better than the high oxygen group. The patterning of early and late oxygen readings was examined. No correlation was found between the cord sample and the 60-minute sample, and the correlation between the 10-and 60-minute samples was low, although statistically significant. In the total group of both uncomplicated and complicated deliveries, infants having cord oxygen above the 50 per cent level showed no greater tendency to be above 90 per cent at one hour than did infants with cord readings below 50 per cent. In complicated deliveries only, those infants with cord readings below 50 per cent were significantly less well oxygenated at one hour than were those whose cord readings were above 50 per cent. It was concluded that the measure of oxygen saturation, while having high face validity and objectivity, does not provide an entirely satisfactory measure of what is clinically regarded as anoxia. The cord sample, which should be the most revealing of the oxygen economy of the infant at the moment of birth, appears likely to be influenced by events of the moment and is unreliable as a predictor of later oxygen status. It was suggested that one of the difficulties with the oxygen measure is the fact that it is too sensitive to transitory states to be serviceable in predicting long-term effects upon the organism.

This paper presents some recent studies on the influence of atmospheres, modified as to their oxygen level and temperature, on the storage life of Wickson plums. Nine temperatures (32°-95° F) were used at each of ten oxygen levels (1-100 per cent). The results show that fruits reached respiration and ripening peaks fastest at 77° in the temperature series, although initial CO2 production increased with temperature to the 95° level. In the oxygen series, the rate of acceleration was roughly proportional to the oxygen tension. Respiration and ripening were increasingly delayed in the lower oxygen levels and at reduced temperatures. At increasing temperatures, fruits in the lowest oxygen levels began to produce as much or more CO2 as fruits in next highest oxygen levels; at 77° the 10 per cent oxygen lot was surpassed by the three lower oxygen lots in reverse order. This is attributed to anaerobic respiration not balanced by the aerobic phases. Ripening failures and loss of vitality of all oxygen lots at 86° and 95° are thought to have resulted from disturbances of the enzyme systems under high temperature.

By polarographic determination of the dissolved oxygen concentration of media used to flood eggs of Aedes aegypti and A. nigromaculis , the effect of dissolved oxygen in stimulating hatching was found to be twofold. An inverse relation occurred between dissolved oxygen and hatching of eggs flooded under conditions of static oxygen level, very low levels being required to induce a high degree of hatching. In contrast, even a slight lowering of the oxygen level while eggs were flooded proved a powerful hatching stimulus. A decline lasting several hours was found in the dissolved oxygen level at the soil-water interface of flooded soil, so that a decreasing level, rather merely a very low level, of dissolved oxygen seems to represent the natural mode of stimulation. Exposure of eggs to 50% relative humidity significantly reduced the hatching response as compared with that of eggs kept under high-humidity conditions.

Austenitic stainless steels find widespread use in sodium-cooled reactor systems because of their low corrosion rates and adequate strength. These steels are usually associated with severe galling wear and high unsteady friction when in contact in the absence of conventional lubrication. Experimental work in liquid sodium and in sodium vapour has shown clearly, however, the existence of mild wear processes in which the surface damage is slight and the friction relatively smooth. This type of wear persists for a greater sliding distance in sodium vapour than in sodium liquid at low temperature. Boundary lubrication by complex oxides is shown to be the likely cause of the mild wear, and the effects of changes of oxygen level in the liquid sodium are reported. A tentative explanation of the friction and wear behaviour is given, based on thermodynamic data.

A technique was developed for maintaining the desired oxygen level in biologically active closed systems. In this method, the chemical mechanism used for replenishing oxygen in the system is directly related to O2 consumption and CO2 production.

SummaryThe authors compare the results of functional respiratory exploration and those of right heart catheterism obtained in twelve cases of chronic emphysema. This study allowed them to bring the following points into evidence.Pressure in pulmonary artery was much increased in subjects with severe emphysema (according to Tiffeneau-Drutel’s classification). It was normal in subjects with benign or moderate emphysema.Test of hypoxia (Inspiratory air containing 9 % oxygen) causes a great rise of the pulmonary pressure in subjects of the first group, a slight rise in those of the second group.Reoxygenation induces as a rule a drop of the pressure below the initial level. One may suppose that in chronic emphysema, pressure in pulmonary artery in influenced by the oxygen level in alveolar air and by the arterial blood saturation.However when interpreting the results of the functional tests, one must take into account the increases of pressure due to the anatomical lesions of chronic emphysema.The authors have...

culture methods for growing plants without soil. Cal. Agr. Exp. Sta. Cir. 347. 6. ILJIN, V. S. 1951. Metabolism of plants affected with lime-induced chlorosis (Calciose). Plant & Soil 3: 339-351. 7. ILJIN, V. S. 1951. Metabolism of the grapevine during lime chlorosis. Gardenbauwirs. 17: 33,R-381 (Abst. in Chem. Abs. 28: 6332) 8. ILJIN, V. S. 1945. Salts & organic acids in relation to calciophiles. Flora 37: 265-299. (abstract in Chem. Abs. 39: 4113) 9. LINDSAY, H. L. & D. W. THORNE. 1954. Bicarbonate ion & oxygen level as related to chlorosis. Soil Sci. 77: 271-279. 10. NEISH, A. C. 1949. Production & properties of 2,3-butanediol. Canadian J. Res. 827: 6-8. 1 1. RHODES, W. A., A. WALLACE, & E. M. RommMEY. 1959. Lime-induced chlorosis studied-physiology of disorder investigated to learn role of malonic acid & possibility of a block in organic acid metabolism. Cal. Agr. 13(3): 6. 12. SAYWELL, L. C. & B. B. CUNNINGHAM. 1937. Determination of iron, colorimetr c o-phenanthroline method. Ind. & Eng. Chem. Ann. Ed. 9: 67-69. 13. SCHANDER, H. 1944. The differences & similarities of chlorosis in lupines & wood growth. Gardenbauwiss. 17: 304-369. 14. SCHANDER, H. 1945. The dependence upon external factors of chlorosis of lupines leteus seedlings in sand cultures. Bodenk u Pflanzenernahr. 12: 71-84. 15. SCHANDER, H. 1945. The problems of lime chlorosis in plants. Tohrb. Wiss. Botan. 91: 169-185. (Abstr. in Chem. Abs. 39: 4649.) 16. \VADLEIGH, C. H. & J. C. BROWN. 1952. The chemical status of bean plants afflicted with bicarbonate-induced chlorosis. Botan. Gaz. 113: 373-390. 17. YOUNG, R. H. & L. M. SHANNON. 1959. Malonate as a participant in organic acid metabolism in bush bean leaves. Plant Physiol. 34: 149-152.

Eighty randomly selected male chicks from each of two commercial broiler strains were used in this study. The chicks were hatched in a common incubator. The experiment was carried out over three consecutive 14 day periods. During the first period, equal numbers of chicks from both strains were subjected to deficient (18.07%) and excess (23.71%) levels of oxygen in the air in environmental chambers of identical type. In the second period, chicks from both chambers were kept in normal air and subjected to two diets differing in level of metabolized energy. In the third period a common diet was used for all chicks. At the end of the initial period some behavioral activities were observed using time lapse video-recorder and sound volume recorder. From all three considered independent variables (strains, oxygen levels and diets) the highest (P The largest relative difference in behavior activities between birds in two oxygen levels was found for comfort feeling responses—more frequent in the higher level of oxygen—and in floor pecking—more frequent in the lower level of oxygen. Brain tissues of birds from the higher oxygen level contained more protein and nitrogen. Blood analysis confirmed higher haematocrit volume in blood samples of birds exposed to an excess of oxygen in the air.

Samples of French-Fry sulphited potato cuts were collected from a commercial prepeeler and analyzed for alcohol content and microbial population. Samples prepared in a laboratory were inoculated with a high and a medium level of microorganisms produced by mixing cultures of forty different organisms isolated from spoiled prepeeled potatoes. The potato samples with high microbial populations showed high alcohol contents indicating that the microorganisms contributed both directly by forming alcohol as a metabolic by-product and indirectly by lowering the oxygen level within the packages thereby promoting anaerobic respiration in the potato tissue.

Several models for the analysis of data relating the rate of oxygen uptake to environmental oxygen level have been evaluated. We conclude that the quadratic (or second-degree) polynomial, though hardly perfect, is the best. Data from 31 species of aquatic invertebrates are described by constants of the quadratic (or second-degree) polynomial equation. The results suggest a phylogenetic trend of increasing regulation of aerobic metabolism in response to declining environmental levels as animals acquire structures that effectively insulate their respiring tissue from the habitat. Many of these species apparently cease withdrawing oxygen from their external environment long before they have exhausted its supply. Presumably, those species with long lasting internal oxygen reservoirs, such as gas bubbles or pools of high oxygen affinity hemoglobin, continue to operate aerobic pathways, but those without substantial oxygen storage devices must switch over to anaerobic pathways, despite the availability of small residual volumes of external oxygen.

Oxygen consumption was determined polarographically for Octopus briareus Robson at 20 and 30 °C and at different oxygen concentrations to investigate the ability of octopus to withstand changes in temperature and oxygen depletion during periodic confinement to small bodies of water at low tide. Oxygen consumption was temperature dependent with mean rates of 0.0417 ml O 2 gh . at 20 °C and of 0.0911 ml O 2 gh at 30 °C for animals weighing 250–443 g. At both temperatures O. briareus regulates the rate of oxygen consumption by compensatory increase in the rate of ventilation when the oxygen level falls below 2.8 ml O 2 1 . The fresh sea-water requirements of octopus at temperatures between 20 and 30 °C have been calculated from the oxygen uptake data.

Grass was ensiled in laboratory silos in three separate experiments. In the first two of them, different oxygen treatment levels were achieved by ensiling different weights of herbage in the fixed volume of the laboratory silo. In the third experiment, the quantity of grass ensiled was kept constant, the oxygen level being varied by evacuation and injection of gas. Fermentation changes were followed during the period of ensilage. In all cases, when compared with the controls, oxygen treatments resulted in silages of lower lactate content, higher acetate content, higher pH and volatile N values. Butyrate was present in appreciable amounts in the high oxygen treated silages in Experiments 1 and 3. It was concluded that oxygen trapped in unconsolidated herbage had an adverse effect on fermentation resulting from not only oxidation of sugar but also from a direct effect on the activities of the microflora.

Laboratory experiments were conducted to determine the rate of decomposition of wheat straw added to soil when continuous aeration was conducted with N₂-O₂ gas mixtures containing 0, 0.5, 1.0, 2.5, 5.0, and 21% oxygen at flow rates of ⅛, ¼, ½, 1, and 2 liters per hour. Rates of decomposition and total decomposition were followed by determination of wheat straw carbon evolved as CO₂. Total decomposition at all oxygen levels varied directly with aeration flow rate, except for the 0% level where an inverse relationship was observed. Microbial activity at the 21% oxygen level was greatly stimulated as flow rate increased from ⅛ through 2 liters per hour. A rapid increase in microbial activity occurred for the 0.5, 1.0, 2.5, and 5.0% oxygen levels as flow rate increased from ⅛ through ½ liters per hour, however, little increase in CO₂ production was observed at higher flow rates.

1. It has been shown that for oxygen practice some of the long-used indicators of metal oxygen level in the open hearth are not as reliable as had been previously supposed. The best readily available relationship for this purpose appears to be that between carbon and oxygen. 2. Data have been presented from which the relationship between carbon, oxygen, and the intensity of the rimming action may be interpreted. It has been shown that there is no correlation between carbon-oxygen product and delayed rimming. This phenomenon appears to be related to the interaction between temperature, metallic deoxidizers, and the driving force for the C-O reaction.

A new spectrochemical technique for determination of hemoglobin content in pale as well as red Daphnia has been presented. By use of this method the primary stimulus for hemoglobin synthesis of low dissolved oxygen content in the culture water has been confirmed. Spectral-Transmittance curves of Daphnia hemoglobin are figured and compared to those of rabbit hemoglobin. A method for controlling the oxygen level in culture flasks by the use of hypodermic needles and air tight rubber caps is described. A first approximation toward a semisynthetic medium for Daphnia is discussed.

SUMMARY In studies of oxygen concentration and scald in commercial soak tanks, scald developed in bruised cherries in tanks with low oxygen concentration in the water. Laboratory experiments with bruised cherries in water or in a nitrogen atmosphere showed that 2 ppm of oxygen is the critical level below which scald develops. No scald developed on bruised cherries kept in water with an almost constant oxygen level of 8.6 ppm, obtained by saturating the water with air at room temperature (23°C) for 91/2 hr. In 1965 the Air-Aqua aeration system was tested under controlled tank storage conditions in Pennsylvania. It proved to be an effective means of increasing the oxygen level of water, thus controlling cherry scald. Aeration also provided more uniform temperatures in the tanks.

Laboratory experiments were conducted to determine the rate of decomposition of straw added to soil as a localized placement or mixed thoroughly with the soil when aerated with N₂-O₂ gas mixtures containing 0, 2.5, 5.0 and 21% oxygen. Rates of decomposition and total decomposition were followed by determination of CO₂ formed. Early decomposition rates were somewhat lower with localized placement of the straw, but after 6 weeks of incubation there was little difference between the two methods of placement in total amount of straw decomposition. Total decomposition after 6 weeks with 5.0, 2.5, and 0% oxygen in the aerating gas was equal to about 86, 70, and 13%, respectively, of that taking place when the aerating gas contained 21% oxygen. After 30 days of aeration at a 0% oxygen level, changing the aerating gas to a 21% oxygen level brought about a very rapid rise in the rate of decomposition.

Johnson, John L. (Montana State College, Bozeman) and Kenneth L. Temple . Some asspects of methane oxidation. J. Bacteriol. 84: 456–458. 1962.—A culture of Pseudomonas methanica ( Methanomonas methanica ) was isolated from a film of growth on the water layer in a methane storage bottle. This organism differed from Dworkin and Foster's strain in pH optimum, requirement for growth factors, sensitivity to oxygen and optimal oxygen level, and minor cultural features. Highly significant interactions were found for the concentrations of oxygen, methane, and carbon dioxide in growth experiments.

Hearts from 5 guinea pigs were excised and simultaneously perfused for 30 min with Krebs-Henseleit solution at 37°C and equilibrated with 95% O2 and 5% CO2. The coronary flow at the end of the equilibration period was taken as the control flow (100%). Thereafter the hearts were perfused for 10 min with solutions equilibrated with various oxygen mixtures (95, 60, 30, 15, 10 and 5% O2). Experiments were performed on two groups of 5 hearts at each oxygen level. Coronary flow was measured and the perfusates were collected for adenosine analysis. At the end of 10 min the hearts were instantaneously frozen and myocardial adenosine and adenine nucleotides were determined. As the PO2 of the gas phase was reduced, per cent change in coronary flow, tissue adenosine and the rate of adenosine release into perfusates were the same for 95 and 60% PO2 but increased in a parallel fashion at the lower PO2 values. However, oxygen consumption remained relatively constant and the estimated energy charge (E = 12ADP + ATPATP + ADP + AMP) decreased slightly. The striking parallelism between coronary flow and adenosine production suggests that the decrease in coronary resistance associated with reduction of oxygen tension in the perfusing fluid may be attributed to the release of adenosine by myocardial cells. Since 5′-nucleotidase is activated in vitro by a decrease in E, it is possible that the small change in the balance of the myocardial adenine nucleotides may control adenosine production.

The case histories of three patients with lung cancer developing radiation myelopathy after cobalt irradiation are described. The frequency with which this complication was seen in patients irradiated in oxygen as compared with that in patients treated in air, suggests that the spinal cord is more sensitive to irradiation when the oxygen level is increased.

A shipping test from Oakland, California to Japan was conducted to determine the effect of a low oxygen controlled atmosphere system (Oxytrol) as well as a new refrigeration system (Cooltainer) on the shelf life of lettuce shipped to military organizations overseas. The Oxytrol system is a complete, self-contained atmosphere control system designed to be used as an adjunct to normal refrigeration equipment in conventional transport vehicles. Results indicated that lettuce shipped under the low oxygen controlled atmosphere system (oxygen level ranged from 2.2 to 4 percent) gave significantly higher edible yields than lettuce shipped in conventional or Cooltainer vans regardless of the packaging (wrapping versus no wrapping) and packing (wirebound wooden boxes versus cardboard wax impregnated boxes). All wrapped lettuce exhibited significantly higher edible yields than unwrapped lettuce regardless of packing and shipping vans. However, no significant difference was shown between lettuce packed in wirebound wooden boxes and that packed in cardboard wax impregnated boxes regardless of the shipping vans.

This paper illustrates the type of conclusions which may be reached by the use of an electrode for measuring oxygen tension in fermentation broths. The critical oxygen level, based on oxygen uptake, and the minimum oxygen tension necessary for maximum antibiotic synthesis for two commercial antibiotic fermentations, capreomycin and cephalosporin C, were studied. Capreomycin yields were depressed at an oxygen tension which was slightly below the critical oxygen level. Cephalosporin C synthesis was depressed at an oxygen tension higher than the critical oxygen level.

Publisher Summary This chapter outlines the general behavior of some fruits and vegetables as indicated by a survey of the literature. Two main aspects of treatment are dealt with: those aimed at extending storage life, and short-term treatments concerned primarily with improved marketing. Attempt has been made to summarize observations made upon the influence of carbon dioxide on post-harvest metabolic phenomena. The commercial use of controlled-atmosphere storage for apples continues to expand, both in those countries that have used it for many years and in those where ad hoe experiments have more recently provided the necessary basis for application of established methods to native varieties. The transport of fruits such as cherries, plums, and soft fruits has been assisted and influenced by the use of dry ice as a source of carbon dioxide gas. For cherries, the control of atmospheric content of carbon dioxide and oxygen with plastic package liners has played a big part in successful storage and transport of the fruit. More accurate specification of the required concentration of carbon dioxide in relation to temperature, oxygen level, and duration of exposure is needed, if controlled-atmosphere treatment is to be applied to products for which it is not in general use at present. The chapter considers some of the best means and methods used for creating the storage environment such as: ventilated stores and scrubbed stores. The applied biologist must define with reasonable accuracy the limits of temperature and concentration of carbon dioxide and oxygen required to attain a defined extension of storage life.

The enzyme lipoxygenase has been demonstrated to produce pentane. However, until now no apparatus has been available to measure the pentane concomitantly with the lipoxygenase activity. Such an apparatus is described by this paper. The apparatus consists of a reaction vessel which can be sealed with a rubber septum to allow sampling for pentane production and an oxygen measuring device to determine the oxygen level of the system. The apparatus is being used to conduct in-depth studies of the lipoxygenase enzyme and its possible role in food quality.

A diffusion-extraction method developed for determination of oxygen in niobium yields reproducible and accurate results. A 0.5-gram sample is heated at 2000 deg C, and evolved gases are analyzed by fractional-freezing technique. Mean deviation at 0.019 weight% oxygen level is less than 0.001 weight%.