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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

'n Ondersoek van die opname en vrystelling van fosforverbindings deur Potamogeton pectinatus L. met behulp van die radio-isotope 32p en 33p

Van Aswegen, Izak Schalk 21 May 2014 (has links)
M.Sc. (Freshwater Biology) / Please refer to full text to view abstract.
182

A study of the relation of phosphorus to keeping quality of pork adipose tissue and rendered lard

Horne, Leroy William January 1938 (has links)
Typescript, etc.
183

Phosphorus availability in two calcareous soils

Gough, Neville Astor January 1961 (has links)
A study was made of the influence of soil moisture tension and soil temperature on the availability of phosphorus from five different compounds in two calcareous soils. In the study of moisture tension, the top six inches of Machete stony sandy loam and of Nisconlith clay loam were treated with five phosphate carriers of varying water solubility, monoammonium phosphate, monocalcium phosphate, anhydrous dicalcium phosphate, calcium metaphosphate and hydroxyapatite, at a rate equivalent to 120 pounds of P₂O₅ per acre. The soils were placed in empty crocks and weighed. These weights were used along with information obtained from previously prepared moisture tension curves to maintain the moisture tension ranges. The tension ranges used were: 0.2 - 0.4, 0.2 - 0.8, 0.2 - 2.0 and 0.2 - 6.0 bars. Irrometers were used to measure and control moisture tension ranges of 0.2 - 0.4 and 0.2 - 0.8 bars. The moisture tension ranges of 0.2 - 2.0 and 0.2 - 6.0 bars were measured gravimetrically. The soils were seeded with alfalfa and placed in growth chambers built in the greenhouse. Three cuttings of the plants were made at the third blossom stage and the dried plant tissue was analysed for phosphorus. At the end of the first cutting, NaHCO₃ extractable phosphorus was determined in these soils and dicalcium phosphate activity at the end of the third harvest. Statistical methods were used to determine the significance of the experimental results. The yields from both soils showed that a moisture tension range of 0.2 - 2.0 bars gave the best growth for the tensions. On the Nisconlith soils the other tensions gave yields that were almost as high as those obtained at 0.2 - 2.0 bars tension. This moisture tension was also the most favourable for phosphorus uptake as indicated by the phosphorus content in plant tissue. The effect of phosphorus source proved to be of no significance on the yield of alfalfa. The phosphorus content in plant tissue from the Machete soil was related to the degree of water solubility of the phosphate compounds. A significant difference between the effectiveness of the water soluble compounds, such as monoammonium phosphate and the water insoluble or citrate insoluble compounds such as hydroxyapatite, was observed. Soil moisture tension had a significant effect on the phosphorus content in plant tissue at a 10% probability. NaHCO₃ extractable phosphorus, removed from both soils after the first cutting, was not directly related to the degree of water soluble phosphorus content of the compounds added. On the Machete soil, monocalcium phosphate treated soil released the greatest amount of NaHCO₃ extractable phosphorus, yet the monoammonium phosphate is ten times more soluble in water. Moisture tension had no effect on the amount of NaHCO₃ extractable phosphorus released. Dicalcium phosphate activity calculated from the calcium, magnesium and phosphorus concentrations in the soil solutions proved to be unsuitable for predicting the availability of phosphorus from the phosphate compounds. These determinations might have proved otherwise if the fertilizer trials were of a shorter duration. In the study of the effects of two soil temperatures 10°C and 24°C, on phosphorus availability, the same two soils, Machete stony sandy loam and Nisconlith clay loam were used. The two soils were potted and five phosphate compounds added at a rate equivalent to 120 pounds of P₂O₅ per acre. These pots were seeded with alfalfa and subjected to soil temperatures of 10°C and 24°C. The first temperature was maintained by the use of a temperature bath placed in the greenhouse and the second temperature was maintained by placing the pots on the greenhouse bench. It was found that at the higher temperature of 24°C higher yields of alfalfa were obtained than at 10°C. No one phosphate source was outstanding in its effect on alfalfa yield from both soils. There was a trend towards increased NaHCO₃ extractable phosphorus with an increase in temperature in both soils. / Land and Food Systems, Faculty of / Graduate
184

Growth, mineral uptake and phosphorus metabolism of Pisum sativum L. as influenced by air and soil temperatures, phosphorus nutrition and growth retarding chemicals

Adedipe, Nurudeen Olorun-Nimbe January 1969 (has links)
In greenhouse and controlled environment experiments, the influences of temperature, P nutrition-, and foliar sprays of 3 growth retarding chemicals on the growth, yield and mineral composition of Pisum sativum L. cv. Dark Skin Perfection were investigated. The utilization of P under 4 air and soil temperature regimes within the physiological range was also studied. The dwarfing effect of high temperature was related to that due to relatively high concentrations of growth retarding chemicals. Banded P fertilizer, applied at rates of up to 352 lb. per acre, increased plant growth, pea yield and the uptake of N, P, K, Ca and Mg. P increased the total contents of all 5 minerals in all 3 tissues (vine, pod and pea seed), but had multiple effects on mineral concentrations. Efficiency of P in producing pea yield increase was maximum at the 44 lb. per acre rate. The high air temperature of 30° decreased growth, pea yield, and total mineral uptake, compared with a temperature of 21°. The high soil temperature of 18° increased these 3 groups of variables, as compared with a temperature of 10°. Increases in mineral concentration at the high air temperature were largely due to "concentration effects'' resulting from smaller plants. Increases due to the high soil temperature were absolute because they occurred even in bigger plants. Increase in mineral uptake at the high soil temperature was not due to increased root growth, but was a result of increased metabolic activity. The effect of soil temperature on total absorption was greater than on translocation into the pea seed. (2-chloroethyl) trimethylammonium chloride (Cycocel) at 1 ppm was the most effective in terms of growth and yield stimulation. 2,4-dichlorobenzyl tributylphosphonium chloride (Phosfon) at 100 ppm was the most effective with respect to growth retardation, but markedly decreased pea yield. N-N-dimethylamino succinamic acid (B-Nine) at concentrations of 1 and 100 ppm was ineffective in altering growth pattern. Effects of the growth retarding chemicals on mineral uptake largely reflected plant size differences, and were not absolute effects. Cycocel and Phosfon at low concentrations are promising for use in arresting excessive vegetative growth and its attendant problems, and in increasing pea yield without deformative effects. The effects of relatively high concentrations of Cycocel and Phosfon were similar to those of high temperatures with respect to plant dwarfing, changes in mineral composition and alteration in the levels of Glucose, G-l-P, G-6-P, F-6-P, Fl,6-P, ADP and ATP. It appears that high concentrations of growth retarding chemicals and high temperatures depress plant growth by reducing the utilization of ATP in the phosphorylation of sugars, in the glycolytic sequence. The nearest-optimal air and soil temperature regime for plant growth and mineral uptake was the 21/13/18° day/night/soil. For uniformity in the nomenclature of plant growth regulators, it is suggested that growth retarding chemicals be called "RETARDINS". / Land and Food Systems, Faculty of / Graduate
185

The effect of abrupt temperature increase on phosphorus metabolism of Pisum sativum

Potts, J. Rowell M. January 1967 (has links)
Pea plants (Pisum sativum cv. Dark Skin Perfection) were grown in a controlled-environment at 25°C day and 15°C night temperature and were then transferred to various high temperature environments. These environments were 32°, 35° and 38°C day temperature with 22°, 25° and 28°C night temperatures respectively. Sample plants were taken at three weeks after planting before transfer to high temperature; and after 1, 10, 100, 1000 minutes and 6 days of exposure to high temperature. The sample plants were analysed for total, organic, inorganic and lipid phosphorus. Growth measurements were also taken. There were no significant changes in the concentrations of organic, lipid and total phosphorus and of inorganic phosphorus except at 6 days exposure to high temperature at which time there was a marked increase in the concentration of inorganic phosphorus. Transfer of plants from the cooler environment to the warmer environments, generally resulted in shorter internode lengths and overall shorter plant height. / Land and Food Systems, Faculty of / Graduate
186

Effects of low levels of 2, 4-dichlorophenoxyacetic acid on the uptake, translocation, and incorporation of P32 by the bean plant (Phaseolus vulgaris)

Etter, Harold MacDonald January 1966 (has links)
A study was carried out to gain information, which could be used to describe the mechanism whereby 2,4-D affects the growth of intact plants. Fourteen-day-old bean plants (Phaseolus vulgaris) growing in a phosphate-free or complete nutrient solutioi were sprayed to drip with 5 or 50 ppm 2,4-D. At various times up to 70 hours after spraying, the roots were immersed in a complete nutrient solution containing P³². Following an incorporation period of 2-9 hours, the plants were harvested, and separated into roots, stems plus petioles, and leaves. Acid soluble activity, acid insoluble activity, and the distribution of activity within the soluble fraction as revealed by paper chromatography were determined for each organ. In general the treatments had relatively small effects on phosphorus uptake, translocation, or incorporation into organic compounds. Initial increases in the rate of P³² uptake were not maintained and were followed by the same or less uptake as controls. The rate of upward translocation was reduced and less affected by the age of-the plants, as compared to controls, after treatment with 5 ppm 2,4-D. The higher concentration did not alter the distribution of activity among the organs. While the lower level did not change the rate of incorporation into the total acid insoluble fraction of the plant, the growth-inhibitory level reduced the activity in this fraction by 14-22%. At 5 ppm there was a trend toward more incorporation into insoluble compounds in the roots and less in the leaves, but no consistent change in the stems. The composition of the soluble fractions showed no uniform variations from controls at either concentration. The results indicated a pattern whereby the balance in P³² distribution between the leaves and roots was upset in favor of the roots by foliar application of 5 ppm 2,4-D, but not 50 ppm. Both stimulatory and inhibitory levels of 2,4-D produced responses which appear to be related to the synthesis of acid insoluble compounds in the roots and leaves. The major portion of the insoluble activity in these tissues was also ethanol insoluble and is believed to be RNA. Actigrapb scans of picric acid chromatograms indicated more incorporation of activity into organic compounds (nucleotides and sugar phosphates) in the leaf and stem tissues than in the roots. Plants grown in complete nutrient prior to exposure to P³² , took up, translocated, and retained less phosphate than those grown in phosphate-free nutrient,. Also, incorporation into soluble organic compounds was suppressed. The only radioactive compound in xylem exudates from plants 10 hours after their initial exposure to P³² was orthophosphate. / Science, Faculty of / Botany, Department of / Graduate
187

Structural studies of halogen, interhalogen and pseudohalogen compounds of phosphorus, selenium and tellurium

Khan, Rana January 2011 (has links)
A series of compounds with the general formula R3PX2 and R3PX4 (where R = o-tolyl, m-tolyl, p-tolyl, o-anisyl, m-anisyl, p-anisyl, o-thioanisyl, p-thioanisyl, p-fluorophenyl, p-chlorophenyl, mesityl and X = Cl, Br, I) have been synthesised and studied by X-ray crystallography, multinuclear NMR spectroscopy and Raman spectroscopy. A study of the conformational features of the aryl groups in these structures was undertaken in order to investigate the role of steric effects and crystal packing on P-X and X-X bond lengths. Compounds with the general formula RSeX / RSeX3 (where R = p-fluorophenyl, p-chlorophenyl, p-bromophenyl, p-iodophenyl and X = Cl, Br, I) have been synthesised by reacting the diselenides with halogens in the stoichiometric ratios. The X-ray crystal structure of p-ClC₆H₄SeI.I₂ is the first crystallographically characterised example of a compound of stoichiometry RSeI₃, although it is better represented as an I₂ adduct of a Se(II) iodide than a Se(IV) compound. In contrast, (p-FC₆H₄)Se-Se(I)₂(p-FC₆H₄) is an I₂ adduct where the Se-Se bond has not been cleaved by iodine. Both structures are stabilised by weak Se...I and I...I interactions. p-FC₆H₄SeCl₃ is an example of a dimeric structure with bridging chlorines. [Ph₄PX] and Ph₃PX₂ were reacted with PhEX (where E = Se, Te and X = I, Br, Cl) to produce salts containing [PhEX₂]- and [PhEX₄] anions. Where possible all the products were then analysed via NMR and Raman spectroscopy and X-ray crystallography. The reactions of the ligand tris-p-fluorophenyl phosphine with sulfur and selenium are presented along with the subsequent reactions of these compounds with diiodine. All of the compounds are characterised via X-ray crystallography.
188

Distribution of Phosphates in a Sewage Plant and its Receiving Waters

Hansard, John D. 05 1900 (has links)
The purpose of this paper is to detail the distribution and quantity of soluble phosphates in an activated sludge plant, its discharge creek, and receiving reservoir. The resultant analyses and comparison of data should provide some better understanding of the fate of phosphorus in a Southwestern waterway system.
189

Fecal Phosphorus Characteristics of Forage-Fed Beef Cattle

Riley, Elizabeth 14 June 2013 (has links)
Phosphorus loads in waterways are a focus of environmental concern. Animal agriculture\'s contribution to this problem has been documented and efforts are focused on mitigating the issue. The effect of increasing amounts of mineral P supplementation on fecal P characteristics was studied in forage fed beef steers. Eight Hereford steers were fitted with total fecal collection bags and fed four diets with a low P grass hay and supplemented with increasing amounts of a mineral source of P, dicalcium phosphate. Dietary DM P concentrations were 0.10 (no P supplementation), 0.23, 0.34, and 0.45% P. Manure was sampled and dried, followed by analysis for total P and inorganic P (Pi). Blood was collected via jugular venipuncture following each collection period and plasma Pi was quantified. Total fecal P increased linearly with increasing dietary P concentration: 6.44, 10.6, 16.1, and 18.8 g/d (P < 0.0001). Fecal Pi increased linearly with increasing dietary P concentration: 1.58, 2.43, 2.74, and 3.84 g/d (P = 0.0119) Manure P solubility, however, did not increase with increasing dietary P concentration: 23.6, 22.3, 17.3, and 20.2% (P = 0.3646). Plasma Pi increased linearly with increasing dietary P (P = 0.0047). ADG and G:F were not affected by increasing dietary P content. Reducing or eliminating mineral P supplementation to forage fed beef animals is possible, if forage base proves to be adequate in P. Reducing dietary P reduces fecal P excretion and the pollution potential in ecologically sensitive areas like the Chesapeake Bay watershed. / Master of Science
190

Structure and synthesis of some phosphorus compounds of potential biological activity

Kyriacou, Panos January 1988 (has links)
Bibliography: 109-110.

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