scholarly journals THE EFFECT OF THE H ION CONCENTRATION ON THE AVAILABILITY OF IRON FOR CHLORELLA SP

1925 ◽  
Vol 9 (2) ◽  
pp. 205-210 ◽  
Author(s):  
E. F. Hopkins ◽  
F. B. Wann
Keyword(s):  
Ph Value ◽  
Maximum Growth ◽  
Chemical Precipitation ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Alkaline Solutions ◽  
Culture Solution ◽  
Hydrogen Ion Concentration ◽  
Chlorella Sp ◽  
Nutrient Solutions

The data obtained in these experiments indicate clearly that unless the necessary precautions are taken to keep the iron of the culture medium in solution the results obtained by varying the H ion concentration will not represent the true effect of this factor on growth. The availability of iron in nutrient solutions has been the subject of numerous recent investigations and it is now known that iron is precipitated at the lower hydrogen ion concentrations, that the iron of certain iron salts is less likely to be precipitated than that of others, and that certain salts of organic acids tend to keep the iron in solution. In general, ferric citrate seems to be the most favorable source of iron. In addition to chemical precipitation, however, it is also possible for the iron to be removed by adsorption on an amorphous precipitate such as calcium phosphate. As this precipitate is frequently formed when nutrient solutions are made alkaline, this may account for the discordant results reported in the literature as to the availability of certain forms of iron. By omitting calcium from the culture solution iron can be maintained in a form available for growth in alkaline solutions by the addition of sodium citrate. In such solutions the maximum growth of Chlorella occurred at pH 7.5. The alkaline limit for growth has not been established as yet. In investigating the availability of iron at varying concentrations of the hydrogen ion, changes in the pH value of the solution during the course of an experiment should also be taken into account. This is especially important in unbuffered solutions. The differential absorption of the ions of ammonium salts may cause a marked increase in the hydrogen ion concentration, which in turn will cause an increase in the solubility of iron. In strongly buffered solutions as used in these experiments this effect is slight.

scholarly journals THE PHAGOCYTOSIS OF SOLID PARTICLES

1923 ◽  
Vol 5 (3) ◽  
pp. 311-325 ◽  
Author(s):  
Wallace O. Fenn
Keyword(s):  
Manganese Dioxide ◽  
Solid Particles ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Alkaline Solutions ◽  
Carbon Electrode ◽  
Acid Solutions ◽  
Small Particles ◽  
Hydrogen Ion Concentration ◽  
Electrode Potentials

1. Leucocytes ingest quartz particles more readily than carbon in acid solutions, and carbon more readily than quartz in alkaline solutions. 2. In the presence of acacia carbon is always preferred to quartz even in acid solutions. 3. Manganese dioxide particles are ingested by leucocytes with extraordinary rapidity as compared with manganese silicate or quartz. 4. Leucocytes are not attracted toward carbon or quartz particles but manganese dioxide exerts a distinct attraction for them. 5. Spores of Penicillium are ingested more readily than quartz. 6. Very small quartz particles, 1 micron in diameter, are not ingested as readily as larger particles of the same material. This result being contrary to the predictions of surface tension indicates that some other factor is involved in the ingestion of these small particles. 7. Measurements of the carbon electrode potentials and the cataphoretic charges on the particles have failed to supply an explanation for the varying relative rates of ingestion of carbon and quartz with varying hydrogen ion concentration.

The Reaction of the Urine in 120 Cases of Mental Disorder

1923 ◽  
Vol 69 (286) ◽  
pp. 327-330
Author(s):  
James Walker
Keyword(s):  
Colorimetric Method ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Alkaline Solutions ◽  
Hydrogen Ion Concentration ◽  
Ion Concentrations ◽  
Satisfactory Method ◽  
Colour Changes ◽  
Standard Solution ◽  
Characteristic Zone

Two methods are available to determine the reaction of a fluid. The first is the method of titration for acidity or alkalinity, in which a standard solution of acid or alkali is added until a certain change in the colour of a suitable indicator is detected. The second method is to determine the hydrogen-ion concentration present in the fluid. The latter is the only satisfactory method of measuring the reaction of a fluid. The hydrogen-ion concentration expresses the reaction of neutral, acid and alkaline solutions. The electrical is the standard method, but for clinical purposes is too intricate. The colorimetric method is less complicated. It is based upon the fact that each indicator has a characteristic zone of hydrogen-ion concentrations within which its colour changes occur. For details as to the theory and technique of this method, the reader may be referred to Clarke and Lubs (J. Bacteriol., 1917, ii), and Cole (Practical Physiological Chem., pp. 19–30).

scholarly journals THE COMPOSITION OF THE CELL SAP OF THE PLANT IN RELATION TO THE ABSORPTION OF IONS

1923 ◽  
Vol 5 (5) ◽  
pp. 629-646 ◽  
Author(s):  
D. R. Hoagland ◽  
A. R. Davis ◽  
Keyword(s):  
Cell Wall ◽  
Higher Plants ◽  
Ph Value ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Inorganic Elements ◽  
Dilute Solutions ◽  
Chemical Examination ◽  
Hydrogen Ion Concentration ◽  
Insoluble Form

1. Chemical examination of the cell sap of Nitella showed that the concentrations of all the principal inorganic elements, K, SO4, Ca, Mg, PO4, Cl, and Na, were very much higher than in the water in which the plants were growing. 2. Conductivity measurements and other considerations lead to the conclusion that all or nearly all of the inorganic elements present in the cell sap exist in ionic state. 3. The insoluble or combined elements found in the cell wall or protoplasm included Ca, Mg, S, Si, Fe, and Al. No potassium was present in insoluble form. Calcium was predominant. 4. The hydrogen ion concentration of healthy cells was found to be approximately constant, at pH 5.2. This value was not changed even when the outside solution varied from pH 5.0 to 9.0. 5. The penetration of NO3 ion into the cell sap from dilute solutions was definitely influenced by the hydrogen ion concentration of the solution. Penetration was much more rapid from a slightly acid solution than from an alkaline one. It is possible that the NO3 forms a combination with some constituent of the cell wall or of the protoplasm. 6. The exosmosis of chlorine from Nitella cells was found to be a delicate test for injury or altered permeability. 7. Dilute solutions of ammonium salts caused the reaction of the cell sap to increase its pH value. This change was accompanied by injury and exosmosis of chlorine. 8. Apparently the penetration of ions into the cell may take place from a solution of low concentration into a solution of higher concentration. 9. Various comparisons with higher plants are drawn, with reference to buffer systems, solubility of potassium, removal of nitrate from solution, etc.

scholarly journals STUDIES ON THE MECHANISM OF ACTION OF IONIZING RADIATIONS

1950 ◽  
Vol 33 (3) ◽  
pp. 229-241 ◽  
Author(s):  
E. S. Guzman Barron ◽  
Veronica Flood
Keyword(s):  
Dissolved Oxygen ◽  
Gamma Rays ◽  
No Reduction ◽  
Ph Value ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
X Rays ◽  
Thiol Compounds ◽  
Hydrogen Ion Concentration ◽  
Ionizing Radiations

Thiol compounds, such as glutathione, 2,3-dimercaptopropanol (BAL), propane-1,3-dithiol, and N-phenylaminopropanedithiol, were readily oxidized by x-rays, beta rays, and gamma rays. The ionic yield for this oxidation was about the same, 3 at pH 7, on irradiation with x-rays and with beta rays; it was 23 per cent less on irradiation with gamma rays. The ionic yield varied with the hydrogen ion concentration, increasing as the pH value increased. There was no reduction of oxidized glutathione on irradiation with dosages of x-rays and gamma rays which produced oxidation of the reduced compound. In the absence of oxygen, the oxidation of thiols by ionizing radiations was only 33 per cent of that obtained in the presence of dissolved oxygen. When the thiol solutions were irradiated in the presence of dissolved oxygen, catalase protected them from oxidation by 17 to 27 per cent.

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