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    From Gas Phase Observations to Solid State Reality: The Identification and Isolation of Trinuclear Salicylaldoximato Copper Complexes
    (MDPI (Basel, Switzerland), 2022-09-29) Roach BD; Forgan RS; Kamenetzky E; Parsons S; Plieger PG; White FJ; Woodhouse S; Tasker PA; Morazzoni F
    Conditions have been identified in which phenolic aldoximes and ketoximes of the types used in commercial solvent extraction processes can be doubly deprotonated and generate polynuclear Cu complexes with lower extractant:Cu molar ratios than those found in commercial operations. Electrospray mass spectrometry has provided an insight into the solution speciation in extraction experiments and has identified conditions to allow isolation and characterization of polynuclear Cu-complexes. Elevation of pH is effective in enhancing the formation of trinuclear complexes containing planar {Cu3-μ3-O}4+ or {Cu3-μ3-OH}5+ units. DFT calculations suggest that such trinuclear complexes are more stable than other polynuclear species. Solid structures of complexes formed by a salicylaldoxime with a piperidino substituent ortho to the phenolic OH group (L9H2) contain two trinuclear units in a supramolecular assembly, {[Cu3OH(L9H)3(ClO4)](ClO4)} 2, formed by H-bonding between the central {Cu3-μ3-OH}5+ units and oxygen atoms in the ligands of an adjacent complex. Whilst the lower ligand:Cu molar ratios provide more efficient Cu-loading in solvent extraction processes, the requirement to raise the pH of the aqueous phase to achieve this will make it impractical in most commercial operations because extraction will be accompanied by the precipitation (as oxyhydroxides) of Fe(III) which is present in significant quantities in feed solutions generated by acid leaching of most Cu ores.
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    Ischaemic Heart Disease and Occupational Exposures: A Longitudinal Linkage Study in the General and Māori Populations of New Zealand
    (Oxford University Press on behalf of the British Occupational Hygiene Society, 2022-05) Barnes LA; Eng A; Corbin M; Denison HJ; 't Mannetje A; Haslett S; McLean D; Ellison-Loschmann L; Jackson R; Douwes J
    OBJECTIVES: This study assessed associations between occupational exposures and ischaemic heart disease (IHD) for males and females in the general and Māori populations (indigenous people of New Zealand). METHODS: Two surveys of the general adult [New Zealand Workforce Survey (NZWS); 2004-2006; n = 3003] and Māori population (Māori NZWS; 2009-2010; n = 2107), with information on occupational exposures, were linked with administrative health data and followed-up until December 2018. Cox proportional hazards regression (adjusted for age, deprivation, and smoking) was used to assess associations between organizational factors, stress, and dust, chemical and physical exposures, and IHD. RESULTS: Dust [hazard ratio (HR) 1.6, 95%CI 1.1-2.4], smoke or fumes (HR 1.5, 1.0-2.3), and oils and solvents (HR 1.5, 1.0-2.3) were associated with IHD in NZWS males. A high frequency of awkward or tiring hand positions was associated with IHD in both males and females of the NZWS (HRs 1.8, 1.1-2.8 and 2.4, 1.1-5.0, respectively). Repetitive tasks and working at very high speed were associated with IHD among NZWS females (HRs 3.4, 1.1-10.4 and 2.6, 1.2-5.5, respectively). Māori NZWS females working with vibrating tools and those exposed to a high frequency of loud noise were more likely to experience IHD (HRs 2.3, 1.1-4.8 and 2.1, 1.0-4.4, respectively). Exposure to multiple dust and chemical factors was associated with IHD in the NZWS males, as was exposure to multiple physical factors in males and females of the NZWS. CONCLUSIONS: Exposures associated with an elevated IHD risk included dust, smoke or fumes, oils and solvents, awkward grip or hand movements, carrying out repetitive tasks, working at very high speed, loud noise, and working with tools that vibrate. Results were not consistently observed for males and females and between the general and Māori populations.
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    Investigation into the interactions of supercritical argon as a solvent with trans-1,2-dichloroethylene using ultraviolet-visible and infrared spectroscopy : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Chemistry at Massey University, Auckland, New Zealand
    (Massey University, 2018) Moffet, Erin Sarah
    This thesis looks at the uses and interactions of argon as a solvent at or above its supercritical temperature and pressure. A supercritical fluid allows for a range of properties depending on where the conditions of pressure and temperature are in relation to the critical point of the chosen substance. These supercritical fluids have been shown to be useful across many areas of industry and research and are the ideal fluid to use in a molecular beam pulsed valve. Solubility interactions of argon and trans-1,2-dichloroethylene (DCE) across multiple conditions were monitored using ultraviolet-visible (UV-Vis) and infrared (IR) spectroscopy. Two high pressure cells were designed, constructed and tested to withstand the 50 atmospheres and 140 K conditions required. The initial cell focused on UV-Vis spectroscopy with the DCE vapour showing an exponential decrease in absorbance as the temperature in the cell was reduced. Changing conditions to reach the supercritical region of argon resulted in a significant increase in the absorbance and therefore the solubility of DCE. The second cell constructed focuses on analysis using infrared spectroscopy and showed clear peak shifts and shape changes at the bu CH stretch (ν9) and bu CH bend (ν10) for trans-1,2-dichloroethylene (DCE) The intensity at au CH bend (ν6) and bu CCl stretch (ν11) proved to be less informative. DCE vapour acted predictably as the temperature was reduced, resulting in a significant drop off in absorbance similar to that observed in the UV-Vis. In changing to the supercritical and liquid argon conditions resulted in the appearance of an asymmetric lineshape characteristic of Fano resonance, which is not common in infrared spectroscopy. This suggest that there is an interaction occurring between a discrete state of DCE that couples to a background continuum process. This Fano resonance does not appear to be present in an argon matrix isolation.
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    Solvent neurotoxicity in vehicle collision repair workers : a thesis by publications presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Public Health, Massey University, Wellington, New Zealand
    (Massey University, 2018) Keer, Samuel John
    Previous studies have shown that vehicle collision repair workers may be at risk of solvent-induced symptoms of neurotoxicity. Changes in industry practices have likely resulted in reduced exposure, but little research has been conducted to assess whether this has reduced the risk of neurotoxicity. This thesis describes a series of studies, which aimed to assess: i) contemporary airborne solvent exposures in collision repair workers; ii) the determinants of airborne solvent exposures; iii) the prevalence of self-reported symptoms of neurotoxicity and objectively measured neuropsychological performance, compared to an unexposed reference group; iv) dose-response associations; and v) the effect of personal protective equipment (PPE) and good workplace hygiene on symptom prevalence. In total, 370 vehicle collision repair and 211 construction workers (reference group) were recruited. Personal airborne solvent exposure was assessed in 85 collision repair workers, and information on demographics, work practices and symptoms was collected by questionnaire. A sub-group of 47 collision repair and 51 reference workers also completed a battery of neuropsychological tests. Full-shift, airborne exposures were well below New Zealand and international occupational exposure limits (range, 0.04 – 16.5 ppm). Job title was the strongest predictor of exposure, and non-spraying tasks (e.g. mixing paint and cleaning equipment) were associated with higher exposures than spray painting itself. Collision repair workers reported significantly more symptoms of neurotoxicity than the reference group, with odds ratios (ORs) of 2.0, 95% CI 1.3-3.3; 2.4, 1.2-4.8; and 6.4, 1.8-23.0, for reporting ≥5, ≥10 and ≥15 symptoms, respectively. They also performed more poorly on neuropsychological tests, particularly those that measure attention/concentration and motor speed/dexterity (e.g. reference vs. collision repair group score on the RBANS total attention scale, -9.5, 95% CI, -15.9, -2.8). Consistent use of PPE (particularly gloves) and good workplace hygiene practices were strongly protective against symptoms, with reductions in risk of up to 90% for those who most consistently wore PPE. In conclusion, despite relatively low airborne exposure levels, collision repair workers continue to be at risk of solvent-induced neurotoxicity. These findings provide a strong evidence-base for the development and implementation of intervention programmes to reduce solvent exposures and associated morbidity in this population.
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    Methodology of culture maintenance and inoculum development for production of solvents by Clostridium acetobutylicum : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Biotechnology at Massey University
    (Massey University, 1985) Gutierrez, Noemi A
    Various methods of culture maintenance and inoculum develop­ment were evaluated for their effectiveness in conserving and improving the property of 2 strains of Clostridium acetobutyicum, namely NCIB 2951 and NRRL B-594, to produce solvents by fermentation of whey permeate. The majority of the methods were effective in maintaining the viability and solventogenic property of the organism. However, since in some cases the viability was maintained but the solventogenic property was not, it is clear that the latter should be used as the index in determining the storage life and time of reprocessing of the stock culture. The methods of culture maintenance investigated included refrigeration at 4°c in distilled water, in phosphate buffer and in Cooked Meat Medium containing glucose ( CMMG) ; by freezing at -20°c in distilled water and in phosphate buffer; by drying in soil and by lyophilization ( freeze drying); and by periodic transfer in CMMG and in whey permeate containing yeast extract. Maintenance of the stock cultures at -20° C in distilled water was found to be the most efficient for the storage stability of both strains of organism. The viability and the potential to produce high solvent concentrations, primarily butanol were maintained without any significant loss after 9 months and 12 months, for strain NCIB 2951 and strain NRRL B-594, respectively. The criteria important for a commercial fermentation, i.e., sugar utilization, yield and butanol production rate, remained stable during storage by this method. It was observed that periodic transfer was a poor method as the culture lost their solventogenic property despite remaining viable. The other preservation methods were not as satisfactory as freezing in distilled water at -20°c since the fermentation ability degenerated to some extent after 9 months of storage. Therefore, after such a period reprocessing of the stock cultures kept by these methods is necessary to revive the cultures and minimize degeneration. The repeated use of the stock cultures was found to be deleterious and should be avoided. The inoculum development procedure investigated to maximize fermentation efficiency included the conventional heat shocking of the stock culture; variation in the number of culture stages; use of gassing as an index of transfer time; and the use of different levels of inoculum size. The strain differences which exist between NRRL B-594 and NCIB 2951 influenced how the inocula from these strains should be propagated prior to fermentation. Strain NRRL B-594 responded to heat shocking while strain NCIB 2951 did not. Neither ethanol nor butanol treatment of the stock cultures of the latter were advantageous. Using a 3-stage inoculum development procedure, the ferment­ation efficiency of strain NRRL B-594 was improved by employing heat shocking at 80C for 15 min in the revival stage of the stock culture. The germination factors for the spores of NCIB 2951 await identification. However, by using the presence of highly motile cells as an index in transferring from the revival stage, the inoculum develop­ment procedure resulted in a significantly higher butanol concentration value and production rate. Thus, the revival stage was the most critical.
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    Intensification of the acetone, butanol, ethanol fermentation using whey permeate and Clostridium acetobutylicum : a preliminary study : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biotechnology at Massey University
    (Massey University, 1987) Ennis, Brett Mills
    The use of whey permeate as the fermentation substrate for the production of acetone:butanol:ethanol (solvents), using C. acetobutylicum P262 was studied. Initial experiments were conducted in a batch mode using sulphuric acid casein whey permeate medium, in an attempt to optimize the culture conditions for maximal extent of lactose utilization and solvents production. A high initial lactose concentration (65-75 g/l) in combination with a culture pH maintained in the region pH 5.4 to 5.6 were the most favourable conditions for solvent production. An inverse relationship between the lactose utilization rate and solvents yield was observed. Solvent productivities were only 60% however, of that achievable with this strain of organism on an industrial scale using a molasses medium, but comparable productivities were obtained using a semi-synthetic medium containing glucose. Hydrolysed-lactose sulphuric acid casein whey permeate medium was investigated as a medium for solvent production. Glucose and galactose were utilized simultaneously, although glucose was used preferentially. Only a small increase in solvents productivity was obtained compared with that obtained using non-hydrolysed permeate. Experiments were performed in continuous culture using cheese whey permeate medium and alginate-immobilized cells. Significantly greater solvent productivities were obtained, compared with those achieved using free cells in batch culture. Fermentations were operated for over 650 hours with no detectable loss in fermentation performance. The extent of lactose utilization was low, however (less than 40%), and attempts to increase this by the use of pH regulation or a two-stage process were unsuccessful. This fermentation process was described as a biomass volume process (volumetric fraction of alginate beads in the reactor), where the lactose utilization and hence the solvents production, was defined by an inhibitory concentration of butanol, approximately 5 g/l. An alternative continuous fermentation process using free cells and cheese whey permeate medium was investigated. External cell recycle using cross-flow microfiltration (CFM) membrane plant to continuously separate cells from the fermentation culture and recycle them back to the fermenter was utilized. Biomass was continuously removed from the fermenter in order to achieve a stable biomass concentration. Stable solvents production was not achieved under the range of culture conditions investigated; culture degeneration was attributed to the complex interactive morphological cyclic behaviour of the organism. A tubular CFM unit which could be periodically backflushed to maintain the filtrate flux, was found to be the most suitable of those tested. The integration of in-situ or in-line solvents recovery with batch culture using free cells, and continuous fermentation using cells immobilized by adsorption to bonechar, was investigated in order to remove toxic solvents and so increase the extent of lactose utilization and solvents productivity. A novel process using gas-stripping with an inert gas, and solvents recovery from the vapour phase by condensation using a cold trap, was described. An increase in lactose utilization and solvents productivity was achieved in both fermentation modes compared with control fermentations. The use of adsorbent resins and a molecular sieve for integrated fermentation solvents recovery was also demonstrated. However, the adsorption of medium components may mitigate against the usefulness of such a process option. The batch refermentation of batch fermentation effluent treated by gas-stripping to remove solvents was investigated. However, solvent production was favoured only when lactose and nutrients were supplemented to concentrations similar to those present originally. Conversely, fermentation medium treated by gas-stripping to remove solvents could be readily refermented to produce solvents when an existing cell population was used, suggesting that this option of an integrated continuous fermentation-product recovery process may be promising for whey permeate solvent production.
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    Role of motility and chemotaxis in solvent production by Clostridium acetobutylicum : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biotechnology at Massey University
    (Massey University, 1989) Gutierrez, Noemi A.
    The motility of Clostridium acetobutylicum P262 and its relationship to solventogenesis were investigated. Motility was monitored in a typical batch fermentation process using sulphuric acid casein whey permeate as substrate. The motile behaviour of C. acetobutylicum was characterized by "runs" wherein the cells were observed to swim in a long, smooth line, then the cells "tumbled" by thrashing around for a few seconds before running again. The "runs" were particularly associated with the early phase of sugar utilization and acid production, while "tumbles" were associated with the onset of solventogenesis. During solvent production, the cells tumbled more frequently and the runs progressively became shorter and slower. The proportion of cells in the culture which exhibited motility increased to almost 100% up to 13h after inoculation, but decreased considerably after this time. Assays for positive chemotaxis (chemoattraction) and negative chemotaxis (chemorepulsion) were performed to identify the chemoeffectors of C. acetobutylicum. Motile cells of C. acetobutylicum were observed to migrate towards glucose, galactose, and lactose. These sugars were identified as attractants. Acetate and butyrate elicited a dual response. Cells were repelled from the dissociated form and attracted towards the undissociated form above a minimum threshold concentration. Chemoattraction to butyric acid was observed at a threshold concentration of 9 x 10-2 M which is similar to the concentration of undissociated butyric acid inside the cell (1.3 x 10-2 M) at which solventogenesis is reported to be initiated, suggesting that the intracellular butyric acid concentration is the likely switch for solventogenesis to commence. The solvents acetone, butanol and ethanol were identified as repellents. The behavioural response of C. acetobutylicum towards the sugars, acids and solvents demonstrates that the motility observed during fermentation is a chemotactic response. Chemotaxis appears to provide survival advantage to C. acetobutylicum. A non-motile mutant was isolated by mutagenesis using ethyl methane sulfonate. This mutant was morphologically indistinguishable from the motile parent strain, such that it possesses flagella in typical number and shape as those of the parent, and is capable of producing clostridial forms and endospores. This type of mutant is a paralyzed mutant and the mutation may be a defect in any of the genes that code for flagellar rotation. The non-motile mutant was capable of solvent production suggesting that motility is not a regulatory mechanism for the switch to solvent production, but merely a behavioural chemotactic response. However, the maximum butanol concentration achieved, the initial rate of butanol production, the yield, and the sugar utilization observed with the mutant were poorer than those of the parent strain. These confirm the positive relationship between motile, chemotactic cultures and solvent production. The low butanol production by the non-motile mutant suggests that the mutant has a lower butanol tolerance than does the parent. Inhibition studies have shown that both growth and solvent production of C. acetobutylicum are subject to end-product toxicity. Growth inhibition studies confirmed that the non-motile mutant was less tolerant to solvents than was the parent. A deficiency in membrane-bound ATPase activity was observed with the non-motile mutant but not in the parent strain. This deficiency in ATPase activity, lack of motility, and lower butanol tolerance may explain the low butanol production by the mutant. On a percentage basis, greater inhibition of solvent production was observed in the parent than in the mutant suggesting that butanol toxicity during the solvent production phase is more profound in the presence of another target site (i.e. ATPase) in addition to the cell membrane. It was further suggested that during growth, butanol inhibition due to membrane disruption was more important than inhibition of ATPase. Thus, chemotaxis prevents C. acetobutylicum from being confined in a toxic situation. Motile cells are more solventogenic because they can chemotactically respond to changes in their environment, and are less susceptible to product inhibition.