title: Development of an Ion Chromatography Method for the Analysis of Nitric Acid Oxidation Reactions of Common Sugars

authors: Davey, Cara-Lee

subjects: nitric acid oxidation

abstract: The large scale nitric acid oxidation of common sugars into their corresponding aldaric acids is being investigated as an important source of potentially useful components for industrial applications such as polymers. 

This thesis details the development of an Ion Chromatography (IC) method for the analysis of these oxidation mixtures and related samples from the work-up and purification processes. The method was developed for use with a Dionex ICS2000 IC system equipped with an AS11-HC column and utilising suppressed conductivity detection. IC proved to be a useful, versatile and straightforward method of studying the reactions and their products. 

The detected ions include but are not restricted to the anionic salt forms of: D-Glucaric acid, Xylaric acid, Mannaric acid,  D-gluconic acid and both keto forms of the same, D-xylonic acid, D-mannonic acid, glycolic acid, oxalic acid, tartaric acid and tartronic acid. Nitrate from the nitric acid used in the oxidation is often observed.  The results compare favorably to GC-MS and HPLC analysis of similar samples. An overview of the theory and operation of the instrument along with the method development and results from application to the oxidation mixtures and related samples are presented. 

As part of the investigation into the range of utility of IC for studying these reactions, a study was made of the retention behaviour of a large number of simple and low molecular weight (LMW) carboxylic acids eluted by the ion chromatography system in use. The results of this study are included with an explanation of the major factors affecting anion retention on the column

text: Development of an Ion Chromatography Method for the Analysis of Nitric Acid Oxidation Reactions of Common Sugars The large scale nitric acid oxidation of common sugars into their corresponding aldaric acids is being investigated as an important source of potentially useful components for industrial applications such as polymers. 

This thesis details the development of an Ion Chromatography (IC) method for the analysis of these oxidation mixtures and related samples from the work-up and purification processes. The method was developed for use with a Dionex ICS2000 IC system equipped with an AS11-HC column and utilising suppressed conductivity detection. IC proved to be a useful, versatile and straightforward method of studying the reactions and their products. 

The detected ions include but are not restricted to the anionic salt forms of: D-Glucaric acid, Xylaric acid, Mannaric acid,  D-gluconic acid and both keto forms of the same, D-xylonic acid, D-mannonic acid, glycolic acid, oxalic acid, tartaric acid and tartronic acid. Nitrate from the nitric acid used in the oxidation is often observed.  The results compare favorably to GC-MS and HPLC analysis of similar samples. An overview of the theory and operation of the instrument along with the method development and results from application to the oxidation mixtures and related samples are presented. 

As part of the investigation into the range of utility of IC for studying these reactions, a study was made of the retention behaviour of a large number of simple and low molecular weight (LMW) carboxylic acids eluted by the ion chromatography system in use. The results of this study are included with an explanation of the major factors affecting anion retention on the column

year: 2008

title: Impact of circadian tuning on the illuminance and color uniformity of a multichannel luminaire with spatially optimized LED placement

authors: Abeysekera, Sanush K.

subjects: Science & Technology

abstract: Potential advantages offered by multichannel luminaires with regards to spectral tuning are frequently overshadowed by its design challenges, a major one being the non-uniformity in illuminance and color distribution. In this paper, we present a formulation using genetic algorithm (GA) to optimize the Light Emitting Diode (LED) placement, yielding 40% superior uniformity in illuminance and color distributions compared to existing analytical formulations, substantially reducing the reliance on optical design for this purpose. It is specifically shown that our approach is employable for circadian tuning applications, even when heavily constrained by industry specifications on panel size and minimum LED separation.

text: Impact of circadian tuning on the illuminance and color uniformity of a multichannel luminaire with spatially optimized LED placement Potential advantages offered by multichannel luminaires with regards to spectral tuning are frequently overshadowed by its design challenges, a major one being the non-uniformity in illuminance and color distribution. In this paper, we present a formulation using genetic algorithm (GA) to optimize the Light Emitting Diode (LED) placement, yielding 40% superior uniformity in illuminance and color distributions compared to existing analytical formulations, substantially reducing the reliance on optical design for this purpose. It is specifically shown that our approach is employable for circadian tuning applications, even when heavily constrained by industry specifications on panel size and minimum LED separation.

year: 2020-01-06

title: The discovery of the Waiorongomai goldfield in 1881

authors: Hart, Philip

abstract: The first reports of gold being found in the vicinity of the Waiorongomai Stream were made in early November 1880, and after the opening of the goldfield a small rush took place to this part of the mountain. The first claims were pegged out in December and the following January, encouraged by some gold being found, but few claims were registered, for most prospectors were quickly disappointed. Prospecting was difficult because of the rugged terrain and heavy bush, and interest quickly faded.
Then, in early October, Hone Werahiko announced his latest and best find and provided samples of payable ore taken from a large reef. Immense excitement ensued, as this was the first payable reef to be found, and after Werahiko led miners on an exhausting trip to his ‘New Find’ a rush set in and many claims were pegged out. The first official to inspect the ground anticipated that the reefs could be easily worked, once an access track was constructed. The small settlement of Te Aroha was revived because a real goldfield had been found, at last.

text: The discovery of the Waiorongomai goldfield in 1881 The first reports of gold being found in the vicinity of the Waiorongomai Stream were made in early November 1880, and after the opening of the goldfield a small rush took place to this part of the mountain. The first claims were pegged out in December and the following January, encouraged by some gold being found, but few claims were registered, for most prospectors were quickly disappointed. Prospecting was difficult because of the rugged terrain and heavy bush, and interest quickly faded.
Then, in early October, Hone Werahiko announced his latest and best find and provided samples of payable ore taken from a large reef. Immense excitement ensued, as this was the first payable reef to be found, and after Werahiko led miners on an exhausting trip to his ‘New Find’ a rush set in and many claims were pegged out. The first official to inspect the ground anticipated that the reefs could be easily worked, once an access track was constructed. The small settlement of Te Aroha was revived because a real goldfield had been found, at last.

year: 2016