A structure-reactivity study of selected phosphorus compounds

Bibliography: p. 366-374.The X-ray crystal structure determinations of a series of ring substituted dimethyl-N-phenyl-phosphoramidates, (R)PhNHP(OCH₃)₂, (R = p-OMe, H, p-NO₂, o-Et and 2,6-diMe) have confirmed the preference of the phosphoramidates for dimer formation which was proposed earlier from infrared data. The formation of N - H - - - - O = P hydrogen bonded dimeric species is sensitive to steric effects and the presence of bulky substituents at the ortho positions of the benzene ring prevents dimer formation. The X-ray crystal structure determination of the carboxylic analogues of the phosphoric amides above, (R)PhNHC(O)R' (R = p-OMe, p-NO₂ and R' = Me or Ph), serves to indicate the differences in the bonding between the phosphoric and carboxylic amides. The geometry of the amide group in the carboxylic amides is subject to the influence of intermolecular hydrogen bonding effects while the phosphoric amide group in the dimer is less sensitive to other intermolecular interactions. In the phosphoric amides the distortion of the amide group from the favourable (planar) geometry arises principally from intramolecular steric repulsions. The bond lengths determined for the phosphoric amides indicate that the phosphoric amide group is less conjugated than the corresponding carboxylic amide group. The P = 0 bond order is insensitive to changes in substituent electron-releasing or -withdrawing ability, The solid state data indicate that the electron density on the nitrogen atom is not transferred to the phosphoryl group as readily as electron density is transferred from the nitrogen atom to the carbonyl group in carboxylic amides. This had previously been suggested from other spectroscopic studies on phosphoric and carboxylic amides. Therefore the approximate reciprocal dependence between the C = O and C - N bond lengths observed in carboxylic amides does not occur in the phosphoric amides. The changes in the electron-withdrawing or -releasing properties of the ring substituent in the phosphoric amides is confined to changes in the acidity of the amide hydrogen atom and is correlated with the N - H ---- 0 = P hydrogen bond length. The angular dependence of the approach of nucleophiles to quaternary phosphonium ions L₄P+ was investigated. The analysis of 36 structures of the general formula L₄P+X- indicates that the nucleophile generally adopts the "face" approach to the phosphonium centre. When the expected leaving group on the phosphorus atom has an acidic α-proton the nucleophile approaches adjacent to the leaving group as a result of a strong interaction between the α-proton and the nucleophile. This tendency had been found previously and is confirmed by this study. When the expected leaving group is of the form OR or NR and there is no possibility of interaction between the nucleophile and the leaving group the nucleophile approaches the phosphonium centre opposite the leaving group. The angular dependence of the approach of the nucleophiles to the phosphonium centres appears to be as a result of packing factors. The crystal structures of the hydrated and dehydrated forms of synthetic analcime indicate that the structures are essentially identical to structure of the natural form determined previously

An investigation of data compression techniques for hyperspectral core imager data

We investigate algorithms for tractable analysis of real hyperspectral image data from core samples provided by AngloGold Ashanti. In particular, we investigate feature extraction, non-linear dimension reduction using diffusion maps and wavelet approximation methods on our data

The relevance of human rights to the socio-economic and political development in South Africa

The concern with the relevance of human rights to the socio-economic and political development in South Africa is of threefold account, namely human rights, socio-economic and political development, and South Africa. Human rights have been consistently applied as a common standard of achievement in the realisation that development cannot be implemented in pure economic terms only, but implies the 'duties of all people towards all other people. For rights only come into their own through practice, the interaction of socio-economic and political facts with values. The importance of the Universal Declaration of Human Rights of I 0 December 1948 is of primary account in this regard. This implies the right to development of all people as well as the classical meaning of equity. The main social function of human rights is to become essential ingredients in legal, political and social reality in each and every country. The socio-economic implementation of human rights in the entire world includes the facts and peculiarities of South Africa in the context of ethnic pluralism. This covers the unrealistic overtones of apartheid, the unabated pressure of the United Nations and the achievement of the new South Africa. There is a great difference between merely criticising and getting things done. An important issue is the sustainability of the RDP, with its emphasis on Mandela's linkage XI between human rights, the rule of law and economic prosperity. COSATU with its unrealistic trade unionism however, remains the chief stumbling block to the unfettered free market economies and investments which are required for genuine job creation. Short of this the RDP and GEAR, which have got off the ground, are in danger of collapse. It is recommended that the ANC should work towards a genuine multi-party democracy at a realistic level where honest criticism is respected. The universal implications of human rights require that people should not be protected overduly simply because they are black at the expense of others who simply happen to be white. Some people are not more equal than others merely by virtue of being white or black.Political ScienceD. Litt et Phil. (Politics

Die kapitalisme en sosialisme in die lig van die werklikheid in Swart-Afrika met besondere verwysing na die Afrika-gebonde staatsfilosofie van kontemporere Tanzanië.

Thesis (M.A.)-University of Durban-Westville, 1980.Sedert die Tweede W!reldoorlog is daar buiten en behalwe die talle artikels en boeke van Nyerere en ander voorstanders van die Afrikasosialisme veel gepubliseer oor die vooruitsigte van die kapitalisme sowel as die kommunisme in Swart-Afrika. Die algemene indruk wat deur hierdie geskrifte geskep word, is dat nog die Westerse sosialisme, nog die doktrinere Leninistiese Marxisme, nog die kapitalisme, onveranderd op die konkrete toestande in Swart-Afrika toegepas kan word. Tot vandag toe is hierdie kontinent besonders eiesoortig, 5005 Scipio Africanus reeds ingesien het, toe hy beweer het dat daar altyd weer iets nuuts uit Afrika verwag kan word ("Ex Africa semper aliquid novit"). In hulle strewe om getrou aan hulleself te wees en teen die hele wereld vry te bly, word die Afrikane deur enkele beslissende faktore in 'n sterk posisie gehou. Eerstens is daar fisieke faktore, 5005 hulle huidskleur en tiperende gelaatstrekke wat die Afrikane van die meeste ander volkere op aarde onderskei en hulle help om van hulle eiesoortigheid bewus te bly. Verder en bowenal is dit die besondere aardrykskundige omstandighede van Afrika wat sy inboorlinge aanmoedig om hulle tradisionele lewenswyse wat hierby aangepas is nie maklik prys te gee nie. Sedert hulle die koloniale juk gedurende die afgelope kwarteeu afgeskud het, het hulle by die Verenigde Volkere -Organisasie en elders al hoe uitdrukliker opgeval as mense wat eiesourtig doen, dink en voel. Die Afrika-persoonlikheid kom besonder duidelik tot uitdrukking in die wyse waarop die Afrikane die kommunisme en die kapitalisme teen mekaar uitgespeel en van albei en almal wat in hulle belang stel deeglik gebruik maak. Dit is veral na aanleiding van hierdie opvallende selfgeldingsdrang dat die onderhawige verhandeling tot stand gekom het onder die titel: "Die Kapitalisme en Sosialisme in die Lig van die Werklikheid in Swart-Afrika, met besondere verwysing na die Afrika-gebonde Staatsfilosofie van kontemporere Tanzanie

Reducing Dimensionality of Hyperspectral Data with Diffusion Maps and Clustering with K-means and Fuzzy ART

It is very difficult to analyse large amounts of hyperspectral data. Here we present a method based on reducing the dimensionality of the data and clustering the result in moving toward classification of the data. Dimensionality reduction is done with diffusion maps, which interpret the eigenfunctions of Markov matrices as a system of coordinates on the original dataset in order to obtain an efficient representation of data geometric descriptions. Clustering is done using k-means and a neural network clustering theory, Fuzzy ART (FA). The process is done on a subset of core data from AngloGold Ashanti, and compared to results obtained by AngloGold Ashanti\u27s proprietary method. Experimental results show that the proposed methods are promising in addressing the complicated hyperspectral data and identifying the minerals in core samples

Just because you're powerless doesn't mean they aren't out to get you: Low power, paranoia, and aggression

Ministry of Education, Singapore under its Academic Research Funding Tier

The pattern of rheumatic heart disease in the urbanized Bantu of Johannesburg

No Abstract

Analysis and exploitation of landforms for improved optimisation of camera based wildfire detection systems

Tower-mounted camera-based wildfire detection systems provide an effective means of early forest fire detection. Historically, tower sites have been identified by foresters and locals with intimate knowledge of the terrain and without the aid of computational optimisation tools. When moving into vast new territories and without the aid of local knowledge, this process becomes cumbersome and daunting. In such instances, the optimisation of final site layouts may be streamlined if a suitable strategy is employed to limit the candidate sites to landforms which offer superior system visibility. A framework for the exploitation of landforms for these purposes is proposed. The landform classifications at 165 existing tower sites from wildfire detection systems in South Africa, Canada and the USA are analysed using the geomorphon technique, and it is noted that towers are located at or near certain landform types

Low power individuals in social power research: A quantitative review, theoretical framework, and empirical test

Data available at OSF https://osf.io/nv4jb/</p