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Item Incremental capacity and voltammetry of batteries, and implications for electrochemical impedance spectroscopy(Journal Article, MDPI AG, 2025)Incremental capacity analysis (ICA), where incremental charge (Q) movements associated with changes in potential are tracked, and cyclic voltammetry (CV), where current response to a linear voltage sweep is recorded, are used to investigate the properties of electrochemical systems. Electrochemical impedance spectroscopy (EIS), on the other hand, is a powerful, non-destructive technique that can be used to determine small-signal AC impedance over a wide frequency range. It is frequently used to design battery equivalent-circuit models. This manuscript explores the relationships between ICA, CV and EIS and demonstrates how sweep rate in CV is related to charging (C) rate in ICA. In addition, it shows the connection between observations linked to rate of charge movement in CV and ICA and intermittent, irregular behavior seen in EIS when performed on a battery. It also explains the use of an additional DC stimulus during EIS to ensure reliability of battery impedance data and to facilitate equivalent-circuit modeling, and suggests a method for obtaining data analogous to CV from a whole battery without risking its destruction.Publication Effects of pasture silage on yield and composition of milk from dairy cows(Thesis, The University of Waikato, 1977)Factors affecting milk yield and composition were reviewed and it was concluded that feeding level and diet type (notably unwilted pasture silage) may have independent effects on yield and composition of milk. The objective of this research was to investigate the separate effects of forage type and feeding level on milk yield and composition and to study some of the mechanisms that may effect the efficiency of utilization of DE in these diets for milk synthesis. Initially effects on milk yield and composition and nutrient utilization were studied in a series of experiments in which dairy cattle were individually fed in stalls on varying levels of forage diets. Unwilted pasture silage was compared with pasture, wilted silage, formalin treated silage, and unwilted silage supplemented with pasture, maize silage or protein concentrates. These experiments showed that both level of feeding and the type of forage diet offered to dairy cows can affect milk yield and composition. Increasing the intake of pasture, increased the yields of milk, fat, protein and lactose, and increased milk protein percentage and decreased milk fat percentage. Similar results were obtained with unwilted silage except that no relationship was found between silage intake and milk protein concentration. Cows offered unwilted pasture silage produced less milk containing a lower concentration of fat and protein than cows offered pasture at the sane intake of DE. percentage. Neither ration affected milk lactose percentage. The efficiency of utilization of DE for milk synthesis by cows fed silage was improved by either reducing protein degradation during ensiling, or by providing pasture or protein concentrates as supplements. Maize silage as a supplement had no effect. These studies indicated that the amount of protein entering the duodenum of cows offered unwilted silage was limiting milk protein synthesis. Subsequently cows were surgically prepared with abomasal cannulae to test this hypothesis. Consistent and significant increases in milk yield, milk protein concentration and milk protein yield by cows fed unwilted silage were obtained when abomasal infusions of sodium caseinate were given in a series of studies. Further studies showed no responses were obtained with abomasal infusions of glucose which indicated that the response in milk protein synthesis was due to amino acids per se. The magnitude of the responses in milk protein synthesis to abomasal infusions of casein were higher for cows offered silage in comparison to those fed pasture at similar intakes of DE. The difference in the responses of the cows on the two rations was due apparently to an inadequate supply of essential amino acids for cows fed silage in comparison with those fed pasture. Abomasal infusions of L-methionine increased milk yield, milk protein percentage and milk protein yield to the same extent as casein suggesting that methionine might be the major essential amino acid that was limiting milk protein synthesis of cows fed unwilted pasture silage.Publication Studies of catalysis of the hydrolysis of phenyl glycinate and some related esters(Thesis, The University of Waikato, 1979)This thesis reports the results and conclusions from the first kinetic studies undertaken of the hydrolysis of phenyl ester of an α-amino acid (glycine), previous studies having been limited to 4-nitrophenyl esters. Some data on 4-methoxyphenyl glycinate are also reported, together with some new data on 4-nitrophenyl esters required for comparison purposes. Studies have concentrated on catalysts previously reported as effective in the hydrolysis of 4-nitrophenyl esters of amino acids, the aim being to determine if results for a phenyl ester with a relatively poor leaving group might help in determining mechanisms involved in catalysis. (i) HCO₃⁻. Unlike the case for 4-nitrophenyl esters, phenyl glycinate hydrolysis is catalysed in bicarbonate solutions not by CO₂ as previously suggested but by HCO₃⁻, the kinetic form is given by Rate= k[neutral ester][HCO₃⁻] Kinetically equivalent forms involving CO₂ and CO₃²⁻ terms have been excluded. Comparison of the catalytic effect of HCO₃⁻ with that of imidazole and that of HPO₄²⁻ excludes the possibilities of general base and nucleophilic catalysis by HCO₃⁻ and a mechanism involving initial nucleophilic addition of amine to HCO₃⁻ followed by intramolecular nucleophilic substitution is suggested as most likely. (ii) 4-nitrobenzaldehyde. Phenyl and 4-methoxyphenyl glycinate show the same kinetic form as 4-nitrophenyl esters but the catalytic effects are much smaller and consistent only with rate-determining attack on ester carbonyl. This supports the concept of rate-determining decomposition of a carbinolamine species, which is also consistent with an observed small effect of temperature on the overall catalytic rate constant. (iii) Imidazole. Unlike the case for 4-nitrophenyl esters, the kinetics are dominated for both neutral and protonated phenyl glycinate species by a term second order in imidazole, which is consistent with general base catalysis of nucleophilic substitution by imidazole in the formation of an acylimidazole intermediate. A term first order in imidazole makes a minor contribution and probably represents general base catalysis as indicated through comparison of the magnitude of the catalytic effect of imidazole with that of HPO₄²⁻, which is also reported on for the first time in this thesis. (iv) N-ethylmorpholine. An unusual non-linear dependence of the observed first order rate constants on catalyst concentration is shown to be consistent with complexing of N-ethylmorpholine and ester prior to reaction. Equilibrium constants for complex formation and rate constants for decomposition are evaluated. However, the effects of model compounds as tests for medium effects of the amine and its cation throw some doubt on the validity of this interpretation. In particular, dioxane, as a model for N-ethylmorpholine, has an inhibitory effect on the hydrolysis of unprecedented magnitude. (v) Hydroxide. Alkaline hydrolysis of phenyl glycinate has been studied so as to obtain rate constants for both the neutral and cationic ester species. The latter is about 300 times more reactive. Studies on 4-nitrophenyl esters have also been advanced in tandem with those of the phenyl and 4-methoxyphenyl esters. The kinetic form for catalysis in bicarbonate solutions has been confirmed as involving CO₂ and not HCO₃⁻, as is consistent with carbamate formation, but whether formation or decomposition of carbamate is rate-determining is still uncertain. The small effect of temperature on reaction rate together with the lack of base catalysis in the reaction support rate-limiting decomposition of carbamate, but the overall rate is close to that predicted by interpolation from other studies for carbamate formation. The possibility of hydrolysis at the zwitterion stage is considered. New data are also reported for 4-nitrobenzaldehyde catalysis for comparison with those of the phenyl and 4-methoxyphenyl esters.Publication Sodium relations in pasture and fodder plants grown in New Zealand(Thesis, The University of Waikato, 1977)The results of an extensive geographical survey of sodium and potassium values in topdressed ryegrass-white clover pastures clearly indicate that in many areas of New Zealand, particularly inland where the influence of sea spray is minimal, herbage sodium levels are below those needed for grazing animals. Moreover, as a direct result of the increased use of potassic fertilisers, particularly in the North Island, most pastures now have potassium levels well in excess of plant needs. Because potassium suppresses plant uptake of sodium and increases the leaching loss of sodium from the soil, it was concluded that excessive use of potassic fertilisers would be expected to aggravate or even create an animal-nutrition problem involving sodium. An additional animal-nutrition problem involving sodium is discussed in relation to the considerable differences measured in the extent to which the more important pasture and fodder species grown in New Zealand were able to absorb and translocate sodium from roots to shoots. In this respect plants can be classified into two distinct types according to the sites where sodium preferentially accumulates. Natrophilea: plants in which sodium readily accumulates in the leaf tissues. Natrophobes: plants in which sodium preferentially accumulates in the roots or lower stems with the result that only vary small quantities of this element are present in the leaf tissue. Because of this intrinsic physiological difference, natrophobes are unable to provide enough sodium for dietary needs of animals, even in a situation where there is enough sodium in the soil to produce satisfactory levels in natrophiles. In view of the depressing effects of potassium, the high risk of leaching under the humid weather conditions which prevail in New Zealand and the differences between plant species in their ability to translocate sodium, it seems that the most practical solution for correcting sodium deficiencies in grazing animals would be the direct supplementation with this element. Apart from the fundamental differences in the sites of sodium accumulation in natrophiles and natrophobes there are a number of other important features which further characterise these two distinct types of plant. In both natrophiles and natrophobes there is a significant relationship between sodium and nitrogen. What is more, both nitrate nitrogen and nitrate reductase activity, as measured by an in vivo method, were found to be predominately located in tissues where sodium readily accumulates. ln other words, nitrate reduction in natrophiles tends to occur in the aerial tissues whereas in natrophobes reduction occurs mainly in the roots and stems. Furthermore, it was concluded that the observed stimulation of nitrate reductase activity in tissues from both natrophiles and natrophobes, due to the addition of sodium chloride, was the result of an increase in nitrate nitrogen at the sites of reduction rather than any specific effect of sodium. However, the possibility that sodium has a stabilising effect on the nitrate reductase enzyme is discussed. From an ecological point of view it seems reasonable to suggest that natrophobes have developed their characteristic distribution of sodium and nitrate reductase activity, along with lower transpiration rates in order to tolerate more arid conditions than those which can be experienced by natrophilic plants.Publication An economic analysis of hospital costs in New Zealand(Thesis, The University of Waikato, 1977)The main purpose of this study is to apply economic principles and methods to the analysis of New Zealand’s hospital services in order to ascertain how the costs of providing those services varies among hospitals and over time. Achievement of this objective at the same time enables an assessment to be made of the relevance of the various theoretical models and empirical techniques that have been employed in recent studies of hospital costs in other countries. Attention in the initial chapters is devoted to identifying and assessing the quantitative importance of the factors responsible for the rapid and accelerating cost increases associated with the provision of hospital services in recent years. Two main groups of factors are identified - demand and supply-related - and their relative cost impacts are tested first by means of a descriptive historical analysis, and then, following the development of a general behavioural model of hospital cost inflation, by means of econometric techniques. The results of the estimation process indicate that rising hospital costs are largely due to changes on the supply side, particularly to the rising cost, quantity and quality of the labour and non-labour inputs used by hospitals. Demand variables, particularly changing length of stay and the changing diagnostic mix of patients treated in hospital, are also shown to have had an important, though less substantial impact on hospital cost levels. The second part of the study is devoted to identifying and examining the factors that give rise to variations in costs among hospitals at a given point in time. Three main groups of factors are identified - patient or output characteristics, institutional characteristics and utilisation levels, and their relative importance in explaining the interhospital cost variations is tested by means of econometric techniques. The results indicate that variations in the average costs of hospital care are largely explained by the types of patient treated, both by age and diagnosis, by the length of time the patient stayed in hospital, and by the teaching status of the hospital. Considerable attention in this section is also devoted to establishing whether economies of scale exist in New Zealand’s hospital industry and to developing and testing a number of alternative measures of hospital output based on similar measures employed in earlier overseas studies. A number of implications for policy and for further research arise from the findings. On the cost inflation side apart from suggesting possible ways in which to combat and control the rapid rise in hospital costs, considerable emphasis is placed on the need both for more rigorous evaluation of alternative hospital expenditure programmes and for more and better planning of all hospital and health services. Future research, it is argued, should be directed towards assessing the costs and benefits of particular hospital programmes with a view to ensuring the most efficient and effective utilisation of the scarce resources available for hospital care in New Zealand. On the cost variation side a revised system of allocating finance to Hospital Boards is advocated which would take into account the various differences among hospitals found to be responsible for the wide variations in their average costs. Introduction of such a population-based allocation system would, it is maintained, ensure that the desired objective of an equitable distribution of resources throughout New Zealand is achieved. Further research is required firstly, to develop a simple yet reliable means of accounting for interboard case-mix differences; secondly, to assess more accurately the nature and extent of the impact of teaching on hospital costs; and finally, to ensure that the economies of scale that appear to exist in New Zealand’s hospital industry are fully exploited.
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