scholarly journals Fundamental Studies on Crop Disease Control by Spraying Electrolyzed Strong Acid Water. (1) Effects of Hydrogen-Ion Concentration Exponent and Free Effective Chlorine Concentration on the Control of Powdery Mildew on Cucumber Leaves.

1998 ◽  
Vol 36 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Kazuhiro FUJIWARA ◽  
Mitsuo IIMOTO ◽  
Mikiko FUJIWARA
Keyword(s):  
Powdery Mildew ◽  
Disease Control ◽  
Strong Acid ◽  
Chlorine Concentration ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Water ◽  
Hydrogen Ion Concentration ◽  
Crop Disease

scholarly journals The Hydrogen Ion Concentration of Sea Water in its Biological Relations

1922 ◽  
Vol 12 (4) ◽  
pp. 717-771 ◽  
Author(s):  
W. R. G. Atkins
Keyword(s):  
Carbon Dioxide ◽  
Methyl Orange ◽  
Hydrochloric Acid ◽  
River Water ◽  
Sea Water ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Water ◽  
End Points ◽  
Hydrogen Ion Concentration

It has long been known that sea water is alkaline and numerous determinations of its alkalinity have been made. The method adopted was the usual one for mixtures of carbonates and bicarbonates, or some modification of it. Those waters which give no colour with phenolphthalein contain bicarbonate only, but for the most part ocean waters have a small amount of carbonate also. Owing to the presence of larger amounts of carbonates and bicarbonates the reaction of sea water is more stable than that of rain or river water, inasmuch as it has a greater alkaline reserve which acts as a “buffer.” The significance of this has been pointed out by Moore, Prideaux, and Herdman (1915) and by other workers. The measurement of alkalinity was carried out by the above named using N/100 hydrochloric acid and titrating to the end points with phenol phthalein and methyl orange. The results are recorded in cubic centimetres of centinormal acid per 100 c.c. of sea water; this is convenient as it is what is measured directly, but others adopt the perhaps more rational notation of milligram equivalents of hydroxyl per litre (Buch, 1914). One cubic centimetre of N/100 acid per 100 c.c. corresponds to 0.1 milligram equivalent per litre. Some workers on fresh waters, Birge and Juday (1911) for example, consider water as acid if it contains more carbon dioxide than that sufficient to convert the carbonate into bicarbonate, and titrate back to a pink with phenolphthalein. Their acid water is, however, still alkaline to methyl orange.

scholarly journals THE INFLUENCE OF HYDROGEN ION CONCENTRATION ON THE INACTIVATION OF PEPSIN SOLUTIONS

1920 ◽  
Vol 2 (5) ◽  
pp. 465-470 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Marked Effect ◽  
Strong Acid ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Slow Increase ◽  
Hydrogen Ion Concentration ◽  
Optimum Range ◽  
Enzyme Solution

1. Pepsin in solution at 38°C. is most stable at a hydrogen ion concentration of about 10–5 (pH 5.0). 2. Increasing the hydrogen ion concentration above pH 5.0 causes a slow increase in the rate of destruction of pepsin. 3. Decreasing the hydrogen ion concentration below pH 5.0 causes a very rapid increase in the rate of destruction of the enzyme. 4. Neither the purity of the enzyme solution nor the anion of the acid used has any marked effect on the rate of destruction or on the zone of hydrogen ion concentration in which the enzyme is most stable. 5. The existence of an optimum range of hydrogen ion concentration for the digestion of proteins by pepsin cannot be explained by the destruction of the enzyme by either too weak or too strong acid.

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