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We previously showed that thioether levels in the exhaled breath volatiles of volunteers undergoing controlled human malaria infection (CHMI) with P. falciparum increase as infection progresses. In this study, we show that thioethers have diurnal cyclical increasing patterns and their levels are significantly higher in P. falciparum CHMI volunteers compared to those of healthy volunteers. The synchronized cycle and elevation of thioethers were not present in P. vivax-infection, therefore it is likely that the thioethers are associated with unique factors in the pathology of P. falciparum. Moreover, we found that time-of-day of breath collection is important to accurately predict (98%) P. falciparum-infection. Critically, this was achieved when the disease was asymptomatic and parasitemia was below the level detectable by microscopy. Although these findings are encouraging, they show limitations because of the limited and logistically difficult diagnostic window and its utility to P. falciparum malaria only. We looked for new biomarkers in the breath of P. vivax CHMI volunteers and found that a set of terpenes increase significantly over the course of the malaria infection. The accuracy of predicting P. vivax using breath terpenes was up to 91%. Moreover, some of the terpenes were also found in the breath of P. falciparum CHMI volunteers (accuracy up to 93.5%). The results suggest that terpenes might represent better biomarkers than thioethers to predict malaria as they were not subject to malaria pathogens diurnal changes.

Currently, the majority of diagnoses of malaria rely on a combination of the patient's clinical presentation and the visualization of parasites on a stained blood film. Breath offers an attractive alternative to blood as the basis for simple, noninvasive diagnosis of infectious diseases. In this study, breath samples were collected from individuals during controlled malaria to determine whether specific malaria-associated volatiles could be detected in breath. We identified 9 compounds whose concentrations varied significantly over the course of malaria: carbon dioxide, isoprene, acetone, benzene, cyclohexanone, and 4 thioethers. The latter group, consisting of allyl methyl sulfide, 1-methylthio-propane, (Z)-1-methylthio-1-propene, and (E)-1-methylthio-1-propene, had not previously been associated with any disease or condition. Before the availability of antimalarial drug treatment, there was evidence of concurrent 48-hour cyclical changes in the levels of both thioethers and parasitemia. When thioether concentrations were subjected to a phase shift of 24 hours, a direct correlation between the parasitemia and volatile levels was revealed. Volatile levels declined monotonically approximately 6.5 hours after initial drug treatment, correlating with clearance of parasitemia. No thioethers were detected in in vitro cultures of Plasmodium falciparum. The metabolic origin of the thioethers is not known, but results suggest that interplay between host and parasite metabolic pathways is involved in the production of these thioethers.

A survey is presented of trends in open-cut and underground mining equipment. DC drive technology has a number of advantages over AC drive and is now used by over 70% of electric shovels. Advances in high-voltage component capacities have allowed the benefits of machinery that operates on higher incoming voltage, while developments in computing have greatly improved the sequencing of operational functions as well as fault diagnosis. The open architecture platform necessary for a load-weighing function allows for the incorporation of features such as optimal dig, intuitive control and condition monitoring. The latest engineering and design tools for equipment development include virtual reality machine construction, extensive finite element analysis and motion simulation., A survey is presented of trends in open-cut and underground mining equipment. DC drive technology has a number of advantages over AC drive and is now used by over 70% of electric shovels. Advances in high-voltage component capacities have allowed the benefits of machinery that operates on higher incoming voltage, while developments in computing have greatly improved the sequencing of operational functions as well as fault diagnosis. The open architecture platform necessary for a load-weighing function allows for the incorporation of features such as optimal dig, intuitive control and condition monitoring. The latest engineering and design tools for equipment development include virtual reality machine construction, extensive finite element analysis and motion simulation.

Toxic substances in application (On) solutions can retard biological leaching of copper sulphide dump ores. On solutions were analysed for metals, organics and chloride and showed inhibitory concentrations of aluminium, manganese, and chloride. The On solution solids were toxic at 50-60% of their field concentration mostly due to the organic fraction. Different solvent extraction reagents show varying degrees of inhibition of Thiobacillus ferrooxidans. Bacterial inhibitory effects of carriers and lixiviants used in the SX plant should be determined so that entrained SX reagents do not retard dump leaching. The reagents used should be the most cost effective and least toxic., Toxic substances in application (On) solutions can retard biological leaching of copper sulphide dump ores. On solutions were analysed for metals, organics and chloride and showed inhibitory concentrations of aluminium, manganese, and chloride. The On solution solids were toxic at 50-60% of their field concentration mostly due to the organic fraction. Different solvent extraction reagents show varying degrees of inhibition of Thiobacillus ferrooxidans. Bacterial inhibitory effects of carriers and lixiviants used in the SX plant should be determined so that entrained SX reagents do not retard dump leaching. The reagents used should be the most cost effective and least toxic.

To enhance bioleaching of copper sulphide dumps, optimal nutrient and pH conditions were determined for the native iron-oxidising bacteria. The optimal ratios of nitrogen:phosphorus were 5:1 to 20:1. The optimal pH was between 1.8 and 2.4 as measured by the iron oxidation rates. When measured by bacterial enumeration, the optimal pH range was 1.4 to 1.6. Shake flask studies were conducted using raffinate and raffinate containing nutrients or bacterial growth medium. The initial rates of copper extraction were doubled when raffinate was supplemented with nutrients. Exogenous strains of Thiobacillus were able to oxidise iron more rapidly than the native strains. However, no greater concentrations of copper were extracted in the presence of the exogenous strains than when only native bacteria were present. The highest rates of molybdenum extraction were achieved using growth media rather than raffinate. Raffinate with nutrient amendments and growth medium were supplemented with T. cuprinus. More copper was extracted when conditions favoured T. cuprinus than when they favoured T. ferrooxidans., To enhance bioleaching of copper sulphide dumps, optimal nutrient and pH conditions were determined for the native iron-oxidising bacteria. The optimal ratios of nitrogen:phosphorus were 5:1 to 20:1. The optimal pH was between 1.8 and 2.4 as measured by the iron oxidation rates. When measured by bacterial enumeration, the optimal pH range was 1.4 to 1.6. Shake flask studies were conducted using raffinate and raffinate containing nutrients or bacterial growth medium. The initial rates of copper extraction were doubled when raffinate was supplemented with nutrients. Exogenous strains of Thiobacillus were able to oxidise iron more rapidly than the native strains. However, no greater concentrations of copper were extracted in the presence of the exogenous strains than when only native bacteria were present. The highest rates of molybdenum extraction were achieved using growth media rather than raffinate. Raffinate with nutrient amendments and growth medium were supplemented with T. cuprinus. More copper was extracted when conditions favoured T. cuprinus than when they favoured T. ferrooxidans.

A new bacterium, Thiobacillus cuprinus, can extract copper from chalcopyrite as rapidly as T. ferrooxidans. On (application) solution with and without nutrient amendments and bacterial growth media were supplemented with Thiobacillus ferrooxidans or T. cuprinus in shake flask studies. Both species extracted about 42% of the copper using growth media. In one case T. cuprinus solubilised about twice as much copper as T. ferrooxidans using seeded On solution. Thiobacillus prosperus also oxidises chalcopyrite and tolerates high chloride concentrations. These sulphide oxidising bacteria are representatives of the mixed microbial community found in sulphide dumps. Rates of biological leaching from copper sulphide ores, using the native microbes, have been significantly enhanced by amending On solution with PGM., A new bacterium, Thiobacillus cuprinus, can extract copper from chalcopyrite as rapidly as T. ferrooxidans. On (application) solution with and without nutrient amendments and bacterial growth media were supplemented with Thiobacillus ferrooxidans or T. cuprinus in shake flask studies. Both species extracted about 42% of the copper using growth media. In one case T. cuprinus solubilised about twice as much copper as T. ferrooxidans using seeded On solution. Thiobacillus prosperus also oxidises chalcopyrite and tolerates high chloride concentrations. These sulphide oxidising bacteria are representatives of the mixed microbial community found in sulphide dumps. Rates of biological leaching from copper sulphide ores, using the native microbes, have been significantly enhanced by amending On solution with PGM.

Mn- or Fe-reducing bacteria of the Bacillus polymyxa and Bacillus circulans groups were cultured and slurried with oxide silver or molybdenum ores in 2 L bioreactors. The growth medium was analysed periodically for solubilised metals by atomic absorption spectroscopy or ICP. The bacteria release target metal ions by dissolving the crystals of pyrolusite, goethite, and haematite within which they are trapped, while their metabolic end-products such as organic acids dissolve zinc and copper without lowering the growth medium pH below 5. Silver recovery from an Arizona manganiferous ore was only 13.7% for a 0.1% cyanide bottle roll, but for bioreductive leaching was 86%, rising to 94.5% if cyanidation of leached solids followed; solubilisation of Mn was 99.8%, Cu up to 99%, and Zn 91%. Molybdenum recovery from a Nevada iron oxide ore was 1.8% for a 5% H2SO4 bottle roll, but 93% for bioreduction., Mn- or Fe-reducing bacteria of the Bacillus polymyxa and Bacillus circulans groups were cultured and slurried with oxide silver or molybdenum ores in 2 L bioreactors. The growth medium was analysed periodically for solubilised metals by atomic absorption spectroscopy or ICP. The bacteria release target metal ions by dissolving the crystals of pyrolusite, goethite, and haematite within which they are trapped, while their metabolic end-products such as organic acids dissolve zinc and copper without lowering the growth medium pH below 5. Silver recovery from an Arizona manganiferous ore was only 13.7% for a 0.1% cyanide bottle roll, but for bioreductive leaching was 86%, rising to 94.5% if cyanidation of leached solids followed; solubilisation of Mn was 99.8%, Cu up to 99%, and Zn 91%. Molybdenum recovery from a Nevada iron oxide ore was 1.8% for a 5% H2SO4 bottle roll, but 93% for bioreduction.