scholarly journals XXVII.—The determination of available plant food in soil by the use of weak acid solvents. Part II

1906 ◽  
Vol 89 (0) ◽  
pp. 205-222 ◽  
Author(s):  
Alfred Daniel Hall ◽  
Arthur Amos
Keyword(s):  
Weak Acid ◽  
Plant Food

scholarly journals XIII.—The determination of available plant food in soils by the use of weak acid solvents

1902 ◽  
Vol 81 (0) ◽  
pp. 117-144 ◽  
Author(s):  
Alfred Daniel Hall ◽  
Francis Joseph Plymen
Keyword(s):  
Weak Acid ◽  
Plant Food

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

Automated and Manual Direct Methods for the Determination of Blood Urea

1965 ◽  
Vol 11 (6) ◽  
pp. 624-627 ◽  
Author(s):  
Walton H Marsh ◽  
Benjamin Fingerhut ◽  
Henry Miller
Keyword(s):  
Acid Solution ◽  
Direct Methods ◽  
Weak Acid ◽  
Ferric Ion ◽  
Diacetyl Monoxime ◽  
Colored Product

Abstract Automated and manual direct methods for the determination of urea in blood or serum are described. These methods determine urea by the colored product formed when urea, in relatively weak acid solution, reacts with diacetyl monoxime in the presence of thiosemicarbazide and ferric ion. Results are compared with those obtained by urease conversion of urea to ammonia and measurement of the ammonia by nesslerization.

scholarly journals The Analysis of the Soil by means of the Plant

1905 ◽  
Vol 1 (1) ◽  
pp. 65-88 ◽  
Author(s):  
A. D. Hall
Keyword(s):  
Phosphoric Acid ◽  
Field Experiments ◽  
Weak Acid ◽  
Point Of View ◽  
Barley Straw ◽  
Plant Food ◽  
Living Plant ◽  
Ash Composition ◽  
Modern Methods ◽  
Plant Grown

One of the main problems placed before the agricultural chemist is the estimation of the requirements of a given soil for specific manures, or the interpretation, by means of data obtained in the laboratory, of the behaviour of the soil towards these manures, as seen in properly arranged field experiments. For various reasons the obvious method of determining the proportions of Nitrogen, Phosphoric Acid, and Potash in the soil fails in many cases to give the required information; even the more modern methods of measuring only the quantities of these materials which are attacked by weak acid solvents, and in consequence regarded as available to the plant, by no means always accord with the results of experience. Hence from time to time attempts have been made to attack the problem from another side and to use the living plant as an analytical agent. The scheme is to take a particular plant grown upon the soil in question, and determine in its ash the proportions of constituents like phosphoric acid and potash. Any deviations from the normal in these proportions may then be taken as indicating deficiency or excess of the same constituent in the soil and therefore the need or otherwise of specific manuring in that direction. The theory rests on two assumptions, first that each plant has a typical ash composition, constant when the plant is grown under similar conditions; secondly that the variations in the proportion of such a constituent as phosphoric acid will reflect the amount of that plant food available in the soil, as measured by the response of the crop to phosphatic manuring. From this point of view a number of investigations have already been made: Hellriegel discussed the relative variations of the proportion of potash in the ash of barley straw and of the soil in which it was grown; Heinrich analysed the roots of oats and fixed certain minima, below which the need for specific manuring was indicated.

scholarly journals On the identification of chitin by its physical constants

1907 ◽  
Vol 79 (534) ◽  
pp. 474-481 ◽  
Keyword(s):  
Specific Gravity ◽  
Weak Acid ◽  
Confirmatory Test ◽  
Text Book ◽  
Diffusion Column ◽  
Chemical Constitution ◽  
Invertebrate Animals ◽  
Intimate Relation ◽  
Physiological Chemistry

The determination of the distribution of chitin in the animal kingdom is hampered by the absence of any test or positive means of identifying it. Gamgee, in his ‘Text-book of Physiological Chemistry,’ gives a list of structures of invertebrate animals in which chitin has been described. But when those cases are eliminated in which the identification has been based solely on the negative character of insolubility in caustic alkalis or weak acid, the revised list, as it appears, for instance, in von Fürth’s ‘ Vergleichende chemische Physiologie der niederen Tiere,’ is greatly curtailed. It is true that chitin yields a characteristic decomposition product, the amido-derivative of sugar known as chitosamin, in definite proportions, but the amount of material available is not always sufficient to allow of the preparation of this product. In cases, however, where we have other reasons for suspecting the presence of chitin, the reducing action of the chitosamin resulting from the treatment of the original substance with sulphuric acid is a valuable confirmatory test. Under these circumstances it seemed that it might be worth while to make a determination of the specific gravity of chitin by the well-known method of a diffusion column. The specific gravity of any substance as thus determined stands in real and intimate relation to its chemical constitution, for the mass dealt with is always small and can therefore be rendered homogeneous by various cleansing processes. It is readily permeated be rendered homogeneous by various cleansing processes. It is readily permeated by the suspending fluid and the absence of any other sources of error may be ensured without difficulty.

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