title: A Reinvestigation of Salvarsan and Related Arsenic Chemistry.

authors: Lloyd, Nicholas

subjects: Salvarsan

abstract: In 1910 the first deliberately targeted search for a new chemotherapeutic agent came to fruition when Paul Ehrlich introduced Salvarsan for the treatment of syphilis. This thesis presents a detailed review of the history and literature leading up to and following on from Ehrlich’s discovery and thoroughly investigates the chemistry of Salvarsan and related species. A series of arylarsonic acids was prepared and fully characterised by electrospray mass spectrometry, NMR and X-ray crystallography for six examples. A detailed analysis of the hydrogen bonding in crystals of these molecules showed that they adopt several characteristic motifs which govern the packing in the crystals. Two of the examples containing NH2 groups crystallised as zwitterions while one NH2 containing example containing other bulky groups was is its molecular form. Salvarsan (cyclo 3-amino-4-hydroxyphenylarsenic(I)) was prepared by several different methods and analysed in detail using high resolution electrospray mass spectroscopy. This showed that Salvarsan consists of small cyclic species of the type (RAs)n where R is 3-NH2-4-OHC6H3 and n is three or greater. The dominant species in an aqueous solution of Salvarsan were found to be (RAs)3 and (RAs)5 . A detailed analysis is presented of impurities in Salvarsan prepared by different methods and also in a sample of original commercial Salvarsan. Mixtures of (RAs)n and (R’As)n exchange R groups in aqueous solution at room temperature, as shown by ESI-MS. ESI-MS studies are reported for the oxidation product of Salvarsan, RAs(OH)2 (commercially known as Mapharsen) and related As(III) compounds. Oligomers involving As-O-As linkages were found in solution and one tetrameric example (R = 3-NO2-4-OHC6H3) was isolated and structurally characterised. Preliminary ESI-MS studies showed that As(III) species bind to thioredoxin, a possible target for the pharmaceutical activity of Salvarsan and its derivatives.

text: A Reinvestigation of Salvarsan and Related Arsenic Chemistry. In 1910 the first deliberately targeted search for a new chemotherapeutic agent came to fruition when Paul Ehrlich introduced Salvarsan for the treatment of syphilis. This thesis presents a detailed review of the history and literature leading up to and following on from Ehrlich’s discovery and thoroughly investigates the chemistry of Salvarsan and related species. A series of arylarsonic acids was prepared and fully characterised by electrospray mass spectrometry, NMR and X-ray crystallography for six examples. A detailed analysis of the hydrogen bonding in crystals of these molecules showed that they adopt several characteristic motifs which govern the packing in the crystals. Two of the examples containing NH2 groups crystallised as zwitterions while one NH2 containing example containing other bulky groups was is its molecular form. Salvarsan (cyclo 3-amino-4-hydroxyphenylarsenic(I)) was prepared by several different methods and analysed in detail using high resolution electrospray mass spectroscopy. This showed that Salvarsan consists of small cyclic species of the type (RAs)n where R is 3-NH2-4-OHC6H3 and n is three or greater. The dominant species in an aqueous solution of Salvarsan were found to be (RAs)3 and (RAs)5 . A detailed analysis is presented of impurities in Salvarsan prepared by different methods and also in a sample of original commercial Salvarsan. Mixtures of (RAs)n and (R’As)n exchange R groups in aqueous solution at room temperature, as shown by ESI-MS. ESI-MS studies are reported for the oxidation product of Salvarsan, RAs(OH)2 (commercially known as Mapharsen) and related As(III) compounds. Oligomers involving As-O-As linkages were found in solution and one tetrameric example (R = 3-NO2-4-OHC6H3) was isolated and structurally characterised. Preliminary ESI-MS studies showed that As(III) species bind to thioredoxin, a possible target for the pharmaceutical activity of Salvarsan and its derivatives.

year: 2011

title: Benchmarking attribute selection techniques for discrete class data mining

authors: Hall, Mark A.

subjects: computer science

abstract: Data engineering is generally considered to be a central issue in the development of data mining applications.  The success of many learning schemes, in their attempts to construct models of data, hinges on the reliable identification of a small set of highly predictive attributes.  The inclusion of irrelevant, redundant and noisy attributes in the model building process phase can result in poor predictive performance and increased computation. 
Attribute selection generally involves a combination of search and attribute utility estimation plus evaluation with respect to specific learning schemes.  This leads to a large number of possible permutation and has led to a situation where very few benchmark studies have been conducted.
This paper presents a benchmark comparison of several attribute selection methods for supervised classification.  All the methods produce an attribute ranking, a useful devise for isolating the individual merit of an attribute. Attribute selection is achieved by cross-validating the attribute rankings with respect to a classification learner to find the best attributes.  Results are reported for a selection of standard data sets and two diverse learning schemes C4.5 and naïve Bayes.

text: Benchmarking attribute selection techniques for discrete class data mining Data engineering is generally considered to be a central issue in the development of data mining applications.  The success of many learning schemes, in their attempts to construct models of data, hinges on the reliable identification of a small set of highly predictive attributes.  The inclusion of irrelevant, redundant and noisy attributes in the model building process phase can result in poor predictive performance and increased computation. 
Attribute selection generally involves a combination of search and attribute utility estimation plus evaluation with respect to specific learning schemes.  This leads to a large number of possible permutation and has led to a situation where very few benchmark studies have been conducted.
This paper presents a benchmark comparison of several attribute selection methods for supervised classification.  All the methods produce an attribute ranking, a useful devise for isolating the individual merit of an attribute. Attribute selection is achieved by cross-validating the attribute rankings with respect to a classification learner to find the best attributes.  Results are reported for a selection of standard data sets and two diverse learning schemes C4.5 and naïve Bayes.

year: 2002-04

title: Discussing future directions in the Maori legal environment

authors: Te Aho, Linda

abstract: The next few years are likely to be exciting in terms of law changes, parliament getting ready for the next election cycle and the end of historical claims settlements. This presentation will look at the future of the Maori legal environment

text: Discussing future directions in the Maori legal environment The next few years are likely to be exciting in terms of law changes, parliament getting ready for the next election cycle and the end of historical claims settlements. This presentation will look at the future of the Maori legal environment

year: 2016