Influence Of Aeration Research Articles

The chloride corrosion of austenitic stainless steels and of an inconel alloy in hot acidic media

Open circuit corrosion testing of austenitic stainless steels, AISI types 304, 310 and 316, and of an Inconel alloy in boiling 5% NaCl solution at pH 2.5 was carried out. The influences of aeration and the introduction of Cl 2 and/or H 2S were also examined. Cl 2 accelerated corrosion, pitting and crack formation whereas H 2S had an inhibiting effect on the corrosion rates and pitting but induced hydrogen attack, which appeared in the form of blisters on the surface specimen. H 2S in the absence of oxygen resulted in the growth of corrosion product on the specimen surface, instead of dissolution, but the cracking tendency also increased due to hydrogen penetration. Addition of trisodium phosphate to the corrosive solution markedly reduced pitting and lowered the corrosion rate by approximately half. Throughout the various tests it was found that the resistance of different alloys to hot chloride corrosion was in the order 310 > 316 > 304 > Inconel.

Enzymatic Activity in a Semi-gley Soil under the Floodplain Forest in South Moravia

In three profiles of a semi-gley soil under the floodplain forest, variations were studied in the activities of invertase, amylase, cellobiase, cellulase, proteases, and phosphatases. In the surface soil layer, enzymatic activity was found affected by the soil moisture at a significant level, whereas in the deeper soil layers the influence of aeration was more effective. Moreover, significant correlations could be detected between the amount of available nitrogen and protease activity, while the water-soluble phosphorus acted as a represeive agent on the activity of phosphatases. Existence of correlations between the numbers of microbes and enzymes could be demonstrated for invertase and protases only.

THE MICROBIOLOGY OF ALBERTA MUSKEG

The microbiology of a Fibrisol (little decomposed), a Mesisol, and a Humisol (highly fermented) were compared to a depth of 1.25 m. Counts of up to 2 million psychrophilic bacteria per gram oven-dry weight were common for the shallow fibric horizons, whilst the deeper and more humified layers generally had much higher counts of 3–10 million. Mesophilic bacteria were about one-fifth more abundant, but thermophiles averaged less than 1 million. The influence of aeration in the top 15 cm increased counts noticeably. From 1 to 6 million fungi were present in the top 25 cm but numbers dropped sharply around this depth. The abundance of Cytophaga and Chromobacterium species in the Humisol, and in the humic horizons of Mesisol, is interesting and its significance is discussed. Physiological studies concentrated on the nitrogen cycle, with determinations of nitrification, denitrification, ammonification and nitrogen fixation being made. The only significant conversion was that of proteins to ammonia, and "most probable number" studies showed maximum activity in August, with 30–70 million ammonifying bacteria to a depth of 1 m.

The influence of aeration on the composting of poultry manure-ground corncob mixtures

The influence of the rate of aeration on 1·5 m columns of composting mixtures of 2 parts poultry manure and 1 part ground corncob was investigated. The results indicated that the optimum aeration rate for the production of a stable sanitary compost was 4 litres of air/m 2/min for every 10 cm of composting material up to a maximum depth of about 2·4 m.

Einfluß der Belüftung des Wassers auf Bakterien der Familie Enterobacterieceae und ihre Artenzusammensetzung

Einfluß der Belüftung des Wassers auf Bakterien der Familie Enterobacterieceae und ihre Artenzusammensetzung

INFLUENCE OF AERATION AND OF PANTOTHENATE ON GROWTH YIELDS OF ZYMOMONAS MOBILIS.

Belaïch, Jean-Pierre (Centre National de la Recherche Scientifique, Marseille, France), and Jacques C. Senez. Influence of aeration and of pantothenate on growth yields of Zymomonas mobilis. J. Bacteriol. 89:1195-1200. 1965.-The growth yields and rates of Zymomonas mobilis were measured in aerobic and anaerobic cultures on glucose medium containing yeast extract, amino acids, or ammonium chloride as the nitrogen source. In the absence of yeast extract, pantothenate was required. The growth yield and rate of the cultures in synthetic (amino acids) or minimal (NH(4)Cl) medium supplemented with pantothenate corresponded only to about one-half the "normal" values obtained in the presence of yeast extract, suggesting a situation of energetically uncoupled growth. Attempts to restore normal growth by the addition of various compounds were unsuccessful. Aeration of the cultures resulted in a partial oxidation of ethyl alcohol to acetate, but did not modify the growth yield nor the division time. Both aerobic and anaerobic cells, however, contained cytochrome c and a cytochrome oxidase of the a(2) type, which was completely inhibited by 10(-4)m cyanide. In anaerobically grown cells, an additional cytochrome of the b type was present. The absence of a Pasteur effect suggests that the transfer of electrons by the respiratory chain of Z. mobilis may not be coupled with oxidative phosphorylation. Aeration had no effect on the catalase content of the cells. As shown by C(14)-glucose incorporation, 2 to 3% of the glucose metabolized was assimilated by the cells in both synthetic and rich complex medium. No intracellular glycogen nor poly-beta-hydroxybutyrate was accumulated when growth was limited by nitrogen or by phosphate in the presence of excess glucose.

Influence of Aeration During Gamma Irradiation of Screw-Worm Pupae

Screw-worms ( Cochliomyia hominivorax (Coquerel)) have shown variable response to the standard dose level of gamma rays from cobalt60 sources used in routine production of sterile flies for eradication of this insect. The primary influence was found to be availability of oxygen during irradiation. When pupae were irradiated in a carbon dioxide atmosphere, a dosage of of 11,100 roentgens (r) was required to sterilize the females, compared with only 5,500 r to 6,200 r required in oxygen and air (forced ventilation). Anoxia induced by consumption of oxygen by the pupae produced radiation-protection effects that were intensified by delay prior to irradiation and/ or increased rate of oxygen uptake as pupae advanced in age. In practical tests, a canister made of 1/8-inch mesh aluminum screen provided sufficient diffusion of air to standardize the dosage safely at 6,900 r, with up to 30 minutes’ delay prior to treatment for pupae 5 days of age or older. This dosage reduces by 50% that required under maximum conditions of anoxia encountered in production when a closed canister is used.

Influence of Aeration and Suspended Material on Higher Alcohols, Acetoin, and Diacetyl during Fermentation

The formation of higher alcohols or fusel oil during the fermentation of grape musts was greatly increased under vigorously aerobic conditions compared to anaerobic fermenations. In one free-run must the increase was sevenfold, but it was usually about double the amounts formed under anaerobic conditions. Naturally occurring suspended solids also stimulate higher alcohol formation. Isobutyl and isoamyl alcohols accounted for most of the increase resulting from either aerobic conditions or the presence of suspended matter for which the amounts of <i>n</i>-propyl and active amyl alcohols were little changed. Both grape skins and inert solids stimulated higher alcohol formation. Evidence was obtained to indicate that the influence of suspended solids was attributable to adsorbed oxygen. Very high levels of acetoin and diacetyl were formed under aerobic conditions, and significant amounts of these compounds were found in some submerged culture "flor" sherries.

Influence of oxygen upon growth and respiratory behaviour of fungi from decomposing rye-grass roots

The influence of aeration upon the growth in culture of fungi isolated from decomposing roots of perennial rye-grass and the effects of variation in oxygen concentration upon their respiratory behaviour were investigated. Although the growth of fungi from the outer cortex and root surfaces was impaired in low oxygen concentrations, their high growth rates may have contributed to the production of inhibitory concentrations of carbon dioxide in the growth tubes employed in these experiments. Also, the method of measuring growth (daily increase in length of colony) was not regarded as satisfactory. The respiratory rates of fungi in various oxygen concentrations were measured by manometric methods and the results indicated that the isolates from the inner cortex were more tolerant of low oxygen concentrations than were those from the outer cortex and root surfaces. The respiratory quotients of the fungi from the root surfaces and outer cortex were found to be higher in reduced oxygen concentrations than those of fungi from the inner cortex.

Influence of Aeration upon the formation of Higher Alcohols by Yeasts

The production of higher alcohols is markedly enhanced by oxidative conditions established by either agitation or sparging with air. Isobutyl alcohol synthesis is particularly favored by aerobic conditions. Yeasts with little or no fermentive capability can produce significant amounts of higher alcohols from carbohydrate under oxidative conditions, with very little accompanying formation of ethyl alcohol.

Bewortelingsonderzoek en Ondergrondbewerking in de Noordoostpolder

The aim of this study was to investigate the suitability of the soil layers and profiles for the penetration by roots and of methods of improving root formation by subsoiling. It was assumed that an adequate moisture supply to the crops required a loam layer at least 70 cm thick penetrable by roots. Methods for quantitative and qualitative root studies were discussed. Root formation in a homogeneous loam soil profile 100 cm deep was taken as a standard to assess the root systems found in various soil profiles. For some grain crops and winter swede-rape the shoot and root development from germination till harvest were shown in diagrams. Shoot and root quantities were given for winter wheat. The influences of aeration and texture of soil on root formation and possible causes for poor development were discussed. After a description of root formation in heterogeneous soil profiles the effects of subsoiling on the roots and yields of several crops were given. Three maps of the western part of the North-East Polder indicate which layers hamper root penetration, and to what depth profiles should be loosened. Areas most badly in need of subsoiling are indicated.

The influence of pH value and aeration on the growth of Aerobacter aerogenes and Bacterium coli in defined media.

The total amount of growth of Aerobacter aerogenes and Bacterium coli in glucose ammonium salt media which provided substrates in excess was dependent on the initial pH value in aerated and unaerated cultures. Total crops in aerated cultures were always higher for any particular initial pH value, and for cultures inoculated at pH values less than 7·0 the pH fell to lower values in aerated than in unaerated media. Growth of a culture of A. aerogenes in its (unaerated) stationary phase resumed on aeration; when the pH value at inoculation was 5·0–6·0, the pH continued to fall; when the pH value at inoculation was 6·1–7·0, the pH rose slightly. Growth of similar cultures of Bact. coli lagged when aerated; pyruvate concentrations immediately increased and pH values fell when glucose was in excess but not when it was limiting for growth. The concentration of formic acid produced by fully grown cultures was sufficient to abolish growth in fresh media below pH 5·25 but not at pH 7·0. These observations are discussed in relation to views on the influence of aeration on growth. Relationships between total growth and initial pH value of citrate media were established for aerated and unaerated cultures of A. aerogenes. Growth in unaerated media ceased at pH values slightly higher than those at inoculation, leaving some citrate unconsumed. Aeration then caused growth resumption accompanied by consumption of citrate and a further increase in alkalinity.

Influence of Aeration on Rate of Growth in Cultures

DURING a recent investigation, it was necessary to obtain large quantities of coliform organisms free from agar extractives and from complex peptide material. While working with a simple medium containing ammonium salts (or asparagine) and dextrose, it was found that an enormous increase in growth could be obtained by passing air through the medium. The following conditions were found to be essential to the success of this procedure. (1) The aeration had to be violent and unremitting, and sufficient to maintain the whole of the medium in a state of turbulence. (2) Media of a more complex nature, giving a positive biuret reaction, frothed excessively, and the common foam suppressors failed to control it. (3) The cooling effect of such an air stream was considerable, and immersion of the culture bottle in a water-bath was necessary to overcome this. A practical method of dealing with it in an incubator could not be found. (4) A moderately complex system of air sterilization was unavoidable. (5) Carbon and nitrogen in the medium had to be adjusted to meet the increased growth.

Influence of aeration on the diastatic activity of barley during steeping

1. The immediate effect of steeping barley is one of depression of diastatic activity. This is due to inadequate supply of air in the steep and not to removal of any soluble diastase activator as has been suggested by some previous workers. 2. With extended steeping, the diastatic power of the seed shows definite increase, the effect being observed even in the absence of air. 3. Development of diastatic power in the steeped seed is independent of its capacity to germinate. It is favoured by aeration but is not entirely dependent on it.

The Influence of Aeration and of Sodium Chloride upon the Growth Curve of Bacteria in Various Media

The Influence of Aeration and of Sodium Chloride upon the Growth Curve of Bacteria in Various Media