Investigation of cryolite ratio measurement by potentiometric methods : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Chemical Technology at Massey University, Palmerston North, New Zealand

The cryolite ratio of an industrial aluminium electrolyte can effect many variables within the process including the overall energy efficiency. Careful control of the cryolite ratio is therefore very important. Currently no online measurements of the cryolite ratio are used in industry. The use of potential measurements between a sodium alloy electrode and an aluminium electrode, as a means of cryolite ratio measurement was investigated. The observed potential changes during cryolite ratio step changes were typically of the correct direction and of similar magnitude to the predicted potential changes calculated from activity data. The cryolite ratio of the electrolyte was found to change continuously during experiments. This was mainly due to the evaporation of NaAIF4 , which was identified by X-ray diffraction. This change in the cryolite ratio meant that long term stability of the electrodes was difficult to accurately quantify. Electrode damage was found to occur after several hours of use and was contributed to the intrusion of electrolyte into the porous boron nitride used as the electrode body. Furthermore the activity of the sodium alloy electrode was found to change significantly during experiments due to the loss of sodium into the electrolyte. This damage to the electrodes is thought to have effected the stability of measurements considerably. Dropping metal electrodes were investigated as a possible means of overcoming the changes in electrode activity. The overall stability of the potential measured between a dropping Pb-Na electrode and an aluminium electrode was somewhat better than the stability of potentials measured between two static pool electrodes. Operating difficulties with the dropping Pb-Na electrode combined with the short lifetime of these electrodes makes these electrodes unsuitable for industrial use. Some suggestions have been made for future electrode designs with single use designs recommended as the most viable option especially for industrial use

Terra Australis Incognita during the Age of Exploration: a window into the changing European world view

For nearly two millennia some Europeans believed that a vast, wealthy, and peopled continent, Terra Australis Incognita, lay in the southern ocean, and acted as a stabilizing counterweight to the northern landmasses. The presence of this frontier, if only imaginary, represented geographical opportunity, and served as a psychological safety valve. Until discoverers possessed the ability to accurately chart the southern seas, the existence of the theoretical continent went unchallenged. Two voyagers serve as bookends in this search during the Age of Exploration: Pedro Ferdinand de Quirós (1565-1615), and Captain James Cook (1728-1779). Beyond their actual voyages, these men serve as philosophical representatives of the ages in which they lived: the Renaissance and the Enlightenment. By examining the written records left by Quirós and Cook, one can discern a clear change in the vision of and for the mythical continent. The philosophical distance between Quirós and Cook mirrors the change which took place among intellectuals in Europe during the same period. Quirós sought to form a religious Utopia on Terra Australis. He found the small island of Santo, Vanuatu, and embellished it into a fifth continent of the world. After Quirós, European men of letters moved Terra Australis to the forefront of the popular imagination by using it as a setting for their works. By the time Captain Cook sailed, the Enlightenment was in full flower. The tolerance for Renaissance legend began to wear thin among all but a few ardent believers. Humankind wanted to know exactly what lay in the South Pacific. Cook embodied this empiricism, doggedly sailing around the South Pole until no more room could be found for an additional continent. Terra Australis vanished not only as consequence of navigation and cartography, but in tandem with the emerging scientific ethos. Humankind lost the possibility of ever discovering another vast and wonderful continent, and traded the romance and Christian humanism of Quirós for the skepticism and severity of Cook

Special Cases in Estimating Multiple Missing Values in Linear Models

Missing a single observation, or more, very commonly occurs in observational and designed studies. Estimating a single missing observation and analysis of these types of data is found in literature (Montgomery, 2020). But the estimation and analysis of data becomes more complicated when the study dataset becomes imbalanced due to multiple missing. Though the case of two missing values is the simplest case of multiple missing values, the analytic estimation and analysis will not be as straight forward as in the one missing value case, because two missing can occur in various ways. This thesis will be exploring mainly the idea of multiple missing values in two-way classified data. In Azadeh et al (2008) it is stated that missing values are incredibly common. In order to continue working with the dataset, those missing values must be estimated. There are two different types of missing values: missing at random (MAR) and missing not at random (MNAR) (Efromovich, 2018). This thesis will be focusing specifically on values that are MAR. Values that are MAR are relatively convenient to deal with because each value in the data set has the same probability of being missing. Also, in Gomer and Ke-Hai (2021) it is stated that the cause of missingness being unobserved makes MNAR valuables difficult to deal with, but it is found in literature (Efromovich, 2018). With a MAR in datasets, the missing value can be in any treatment and in any block. With two missing values, each missing value can appear in any treatment and any block which gives three separate cases that will be discussed later. This thesis will also be looking at multiple missing values instead of just one. Estimating for one missing value has been researched extensively, but estimating more than one still has plenty of room for exploration. In Tang \& Ishwaran (2017) and Montgomery (2020), the authors mentioned that their method for estimating missing values is iterative because the estimation of one missing value takes into account the value of the other missing value. This means for the first estimation one of the missing values is given a random number and that is used to compute the second missing value. That second missing value is then plugged in to find the estimation for the first missing value. This process is done over and over until the estimates have stabilized. The method proposed is an analytic method which will provide closed form solution for missing values and will not require the iterative process. Having the analytic solution will allow us to explore the inferential, statistical properties of the estimators

Stretching single polysaccharide molecules using AFM: A potential method for the investigation of the intermolecular uronate distribution of alginate?

Illustrative examples of the way in which the molecular force-extension behaviour of polysaccharides is governed by the nature of the linkage between their constituent pyranose rings are presented for a series of standard homopolymers. These results agree with previously proposed general hypotheses regarding the possibility of generating force-induced conformational transitions, and with the predictions of a model in which the inter-conversion of pyranose conformers is assumed to be an equilibrium process on the timescale of the molecular stretching. Subsequently, we investigate the potential of the technique in the characterisation of co-polymeric polysaccharides in which the nature of the glycan linkages is different between the two distinct residue types. Specifically, we explore the possibility that the ratio of mannuronic acid (M) to guluronic acid (G) in alginate chains will be reflected in their single molecule stretching behaviour, owing to their contrasting equatorial and axial linkages. Furthermore, as the technique described interrogates the sample one polymer at a time we outline the promise of, and the obstacles to, obtaining a new level of characterisation using this methodology where differences observed in the single molecule stretching curves obtained from single alginate samples reflectsomething of the real intermolecular distribution of the M / G ratio

Advances in Our Understanding of Pyroclastic Current Behavior from the 1980 Eruption Sequence of Mount St. Helens Volcano (Washington), USA

This review summarizes what the volcanology community has learned thus far from studying the deposits of pyroclastic currents (PCs) from the 1980 eruption sequence at Mount St. Helens. The review includes mass flow events during the May 18 eruption, including the lateral blast, the afternoon column collapse and boil-over PC activity, and some aspects of the debris avalanche. We also include a summary of PCs generated in the smaller eruptions following the climactic May 18 event. Our objective is to summarize the state of our understanding of PC transport and emplacement mechanisms from the combination of field and laboratory observations, granular flow experiments, and numerical modeling techniques. Specifically, we couple deposit characteristics, experiments, and numerical modeling techniques to critically address the problems of (1) constraining conditions in the flow boundary zone at the time of deposition; (2) the influence of substrate roughness and topography on PC behavior; (3) the prevalence, causes, and consequences of substrate erosion by PCs; and (4) the reconstruction of PC transportation and sedimentation processes from a combination of geophysical and sedimentological observations. We conclude by providing opportunities for future research as our field, experimental, and numerical research techniques advance

Steps for Developing Effective Grant Writing Workshops

Grants can be an important source of funding for new and existing businesses. Yet most business owners have no experience in grant writing and find it intimidating. In this article, we identify steps based on our experiences that Extension educators can take to develop and deliver a successful grant writing workshop

The SWELLS Survey. VI. hierarchical inference of the initial mass functions of bulges and discs

The long-standing assumption that the stellar initial mass function (IMF) is universal has recently been challenged by a number of observations. Several studies have shown that a "heavy" IMF (e.g., with a Salpeter-like abundance of low mass stars and thus normalisation) is preferred for massive early-type galaxies, while this IMF is inconsistent with the properties of less massive, later-type galaxies. These discoveries motivate the hypothesis that the IMF may vary (possibly very slightly) across galaxies and across components of individual galaxies (e.g. bulges vs discs). In this paper we use a sample of 19 late-type strong gravitational lenses from the SWELLS survey to investigate the IMFs of the bulges and discs in late-type galaxies. We perform a joint analysis of the galaxies' total masses (constrained by strong gravitational lensing) and stellar masses (constrained by optical and near-infrared colours in the context of a stellar population synthesis [SPS] model, up to an IMF normalisation parameter). Using minimal assumptions apart from the physical constraint that the total stellar mass within any aperture must be less than the total mass within the aperture, we find that the bulges of the galaxies cannot have IMFs heavier (i.e. implying high mass per unit luminosity) than Salpeter, while the disc IMFs are not well constrained by this data set. We also discuss the necessity for hierarchical modelling when combining incomplete information about multiple astronomical objects. This modelling approach allows us to place upper limits on the size of any departures from universality. More data, including spatially resolved kinematics (as in paper V) and stellar population diagnostics over a range of bulge and disc masses, are needed to robustly quantify how the IMF varies within galaxies.Comment: Accepted for publication in MNRAS. 15 pages, 8 figures. Code available at https://github.com/eggplantbren/SWELLS_Hierarchica

Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats

Citation: Kirkpatrick, K., Marshall, A. T., & Smith, A. P. (2015). Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats. Comparative Cognition & Behavior Reviews, 10. Retrieved from http://comparative-cognition-and-behavior-reviews.org/2015/vol10_kirkpatrick_marshall_smith/Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats Kimberly Kirkpatrick Department of Psychological Sciences, Kansas State University Andrew T. Marshall Department of Psychological Sciences, Kansas State University Aaron P