Elevated plasma membrane and sarcoplasmic reticulum Ca2+ pump mRNA levels in cultured aortic smooth muscle cells from spontaneously hypertensive rats

We have observed previously that Ca2+ pump-mediated Ca2+ efflux is elevated in cultured aortic smooth muscle cells from spontaneously hypertensive rats compared to those from Wistar-Kyoto rat controls. The objective of this work was to determine if these strains differ in mRNA levels for the PMCA1 isoform of the plasma membrane Ca2+-ATPase and the SERCA2 isoform of the sarcoplasmic reticulum Ca2+-ATPase. mRNA levels were compared in cultured aortic smooth muscle cells from 10-week-old male rats. PMCA1 and SERCA2 mRNA levels were elevated in SHR compared to WKY. Angiotensin II increased the level of PMCA1 and SERCA2 mRNA in both strains. These studies provide further evidence for alterered Ca2+ homeostasis in hypertension at the level of Ca2+ transporting ATPases in the spontaneously hypertensive rat model. These data are also consistent with the hypothesis that the expression of these two Ca2+ pumps may be linked. (C) 1997 Academic Press

Trialing wetlands to treat coal mining wastewaters in a low rainfall, high evaporation environment

The large number of wetlands treating mining wastewaters around the world have mostly been constructed in temperate environments. Wetlands have yet to be proven in low rainfall, high evaporation environments and such conditions are common in many parts of Australia. BHP Australia Coal is researching whether wetlands have potential in central Queensland to treat coal mining wastewaters. In this region, mean annual rainfall is < 650 mm and evaporation > 2 000 mm. A pilot-scale wetland system has been constructed at an open-cut coal mine. The system comprises six treatment cells, each 125 m long and 10 m wide. The system is described in the paper and some initial results presented. Results over the first fourteen months of operation have shown that although pH has not increased enough to enable reuse or release of the water, sulfate reduction has been observed in parts of the system, as shown by the characteristic black precipitate and smell of hydrogen sulfide emanating from the wetlands. These encouraging signs have led to experiments aimed at identifying the factors limiting sulfate reduction. The first experiment, described herein, included four treatments where straw was overlain by soil and the water level varied, being either at the top of the straw, at the top of the soil, or about 5 cm above the soil. The effect of inoculating with sulfate-reducing bacteria was investigated. Two controls were included, one covered and one open, to enable the effect of evaporation to be determined. The final treatment consisted of combined straw/cattle manure overlain with soil. Results showed that sulfate reduction did occur, as demonstrated by pH increases and lowering of sulfate levels. Mean pH of the water was significantly higher after 19 days; in the controls, pH was < 3.3, whereas in the treatments, pH ranged from 5.4 to 6.7. The best improvement in sulfate levels occurred in the straw/cattle manure treatment. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

The occurrence of cancer in a cohort of New South Wales coal miners

To describe the incidence of cancer in coal miners in New South Wales (NSW) between 1973 and 1992, an inception cohort of all male coal industry employees who entered the industry between 1 January 1973 and 31 December 1992 was constructed from the medical examination records of the Joint Coal Board. This cohort was matched with the NSW State Cancer Registry to determine the occurrence and type of cancer. In the cohort of 23 630 men, 297 developed 301 primary cancers in the 20-year period of observation. The standardised incidence ratio (SLR) for all cancers was 0.82. Stomach cancer has been reported to be common in coal miners but the SIR for stomach cancer was not higher than average in this cohort. A cluster of non-Hodgkin's lymphoma has been reported in a NSW coal mine but an increased risk of this cancer was not evident in the industry as a whole. Similarly a cluster of cases of brain tumour has been reported. In this cohort, the SIR for brain tumour was 1.05 (95 per cent confidence interval (CI) 0.57 to 1.76) and a risk for brain tumour remains unconfirmed. The SIR for malignant melanoma was 1.13 (CI 0.90 to 1.39) altogether and 2.02 (CI 1.31 to 2.98) for those workers who started in an open-cut mine. Overall, there does not appear to be a general risk of cancer in the NSW coal industry. Open-cut miners have an increased risk of malignant melanoma, which may be related to their exposure to the sun at work.

Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment

OBJECTIVE: To observe the chronic effects of human growth hormone (hGH) and AOD9604 (a C-terminal fragment of hGH) on body weight, energy balance, and substrate oxidation rates in obese (ob/ob) and lean C57BL/6Jmice. In vitro assays were used to confirm whether the effects of AOD9604 are mediated through the hGH receptor, and if this peptide is capable of cell proliferation via the hGH receptor. METHOD: Obese and lean mice were treated with hGH, AOD or saline for 14 days using mini-osmotic pumps. Body weight, caloric intake, resting energy expenditure, fat oxidation, glucose oxidation, and plasma glucose, insulin and glycerol were measured before and after treatment. BaF-BO3 cells transfected with the hGH receptor were used to measure in Vitro I-125-hGH receptor binding and cell proliferation. RESULTS: Both hGH and AOD significantly reduced body weight gain in obese mice. This was associated with increased in vivo fat oxidation and increased plasma glycerol levels (an index of lipolysis). Unlike hGH, however, AOD9604 did not induce hyperglycaemia or reduce insulin secretion. AOD9604 does not compete for the hGH receptor and nor does it induce cell proliferation, unlike hGH. CONCLUSIONS: Both hGH and its C-terminal fragment reduce body weight gain, increase fat oxidation, and stimulate lipolysis in obese mice, yet AOD9604 does not interact with the hGH receptor. Thus, the concept of hGH behaving as a pro-hormone is further confirmed. This data shows that fragments of hGH can act in a manner novel to traditional hGH-stimulated pathways.

Critical review of acid in situ leach uranium mining: 2. Soviet Block and Asia

The technique of in situ leach (ISL) uranium mining is well established in the USA, as well as being used extensively in Eastern Europe and the former Soviet Union. The method is being proposed and tested on uranium deposits in Australia, with sulphuric acid chemistry and no restoration of groundwater following mining. ISL mines in the former Soviet Union generally used acid reagents and were operated without due consideration given to environmental protection. At many former mine sites, the extent of groundwater contamination is significant because of high salinity, heavy metal and radionuclide concentrations compared with pre-mining and changes in the hydrogeological regime caused by mining. After the political collapse of the Soviet Union by the early 1990s, most uranium mines were shut down or ordered to be phased out by government policy. Programmes of restoration are now being undertaken but are proving technically difficult and hampered by a lack of adequate financial resources. The history and problems of acid ISL sites in countries of the former Soviet Union and Asia are presented in this study.

The effect of coal particle size on colorimetric analysis of roadway dust

Colorimetric analysis of roadway dust is currently a method for monitoring the incombustible content of mine roadways within Australian underground coal mines. To test the accuracy of this method, and to eliminate errors of judgement introduced by human operators in the analysis procedure, a number of samples were tested using scanning software to determine absolute greyscale values. High variability and unpredictability of results was noted during this testing, indicating that colorimetric testing is sensitive to parameters within the mine that are not currently reproduced in the preparation of reference samples. This was linked to the dependence of colour on particle surface area, and hence also to the size distribution of coal particles within the mine environment. (C) 2001 Elsevier Science Ltd. All rights reserved.

A multi-purpose rainfall simulator for field infiltration and erosion studies

This paper describes a rainfall simulator developed for field and laboratory studies that gives great flexibility in plot size covered, that is highly portable and able to be used on steep slopes, and that is economical in its water use. The simulator uses Veejet 80100 nozzles mounted on a manifold, with the nozzles controlled to sweep to and from across a plot width of 1.5 m. Effective rainfall intensity is controlled by the frequency with which the nozzles sweep. Spatial uniformity of rainfall on the plots is high, with coefficients of variation (CV) on the body of the plot being 8-10%. Use of the simulator for erosion and infiltration measurements is discussed.

The design of hazard risk assessment matrices for ranking occupational health risks and their application in mining and minerals processing

Two hazard risk assessment matrices for the ranking of occupational health risks are described. The qualitative matrix uses qualitative measures of probability and consequence to determine risk assessment codes for hazard-disease combinations. A walk-through survey of an underground metalliferous mine and concentrator is used to demonstrate how the qualitative matrix can be applied to determine priorities for the control of occupational health hazards. The semi-quantitative matrix uses attributable risk as a quantitative measure of probability and uses qualitative measures of consequence. A practical application of this matrix is the determination of occupational health priorities using existing epidemiological studies. Calculated attributable risks from epidemiological studies of hazard-disease combinations in mining and minerals processing are used as examples. These historic response data do not reflect the risks associated with current exposures. A method using current exposure data, known exposure-response relationships and the semi-quantitative matrix is proposed for more accurate and current risk rankings.

Quantifying stresses and support requirements in the undercut and production level drifts of block and panel caving mines

A numerical modelling strategy has been developed in order to quantify the magnitude of induced stresses at the boundaries of production level and undercut level drifts for various in situ stress environments and undercut scenarios. The results of the stress modelling were in line with qualitative experiential guidelines and a limited number of induced stress measurements documented from caving sites. A number of stress charts were developed which quantify the maximum boundary stresses in drift roofs for varying in situ stress regimes, depths and undercut scenarios. This enabled many of the experiential guidelines to be quantified and bounded. A limited number of case histories of support and support performance in cave mine drifts were compared to support recommendations using the NGI classification system, The stress charts were used to estimate the Stress Reduction Factor for this system. The back-analyses suggested that the NGI classification system might be able to give preliminary estimates of support requirements in caving mines with modifications relating to rock bolt length and the support of production level intersections. (C) 2002 Elsevier Science Ltd. All rights reserved.

Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland

Free-ranging koalas (Phascolarctos cinereus) were monitored by means of radio-relocation in the area of Blair Athol Coal Mine and surrounding properties. Daytime tree use, home range and diet of these koalas was determined in spring and autumn, as was the leaf moisture composition of potential fodder species. Koalas used on average 93 (male koalas) and 56 (female koalas) trees during the period of observation, occupying home ranges of 135 and 101 ha respectively. Mean sightings per tree were 1.19 for both males and females and home-range sizes were not significantly different between sexes or seasons. Koalas were observed returning to previously used daytime roosting trees infrequently (

New arsenite-oxidizing bacteria isolated from Australian gold mining environments - Phylogenetic relationships

Nine novel arsenite-oxidizing bacteria have been isolated from two different gold mine environments in Australia. Four of these organisms grow chemolithoautotrophically with oxygen as the terminal electron acceptor, arsenite as the electron donor, and carbon dioxide-bicarbonate as the sole carbon source. Five heterotrophic arsenite-oxidizing bacteria were also isolated, one of which was found to be both phylogenetically and physiologically identical to the previously described heterotrophic arsenite oxidizer misidentified as Alcaligenes faecalis. The results showed that this strain belongs to the genus Achromobacter. Phylogenetically, the arsenite-oxidizing bacteria fall within two separate subdivisions of the Proteobacteria. Interestingly, the chemolithoautotrophic arsenite oxidizers belong to the alpha-Proteobacteria, whereas the heterotrophic arsenite oxidizers belong to the beta-Proteobacteria.

Engineering closure of an open pit gold operation in a semi-arid climate

Along with material characteristics and geometry, the climate in which a mine is located can have a dramatic effect on the appropriate options for rehabilitation. The paper outlines the setting, mining, milling and waste disposal at Kidston Gold Mine's open pit operations in the semi-arid climate of North Queensland, Australia, before focusing on the engineering aspects of the rehabilitation of Kidston. The mine took a holistic and proactive approach to rehabilitation, and was prepared to demonstrate a number of innovative approaches, which are described in the paper. Engineering issues that had to be addressed included the geotechnical stability and deformation of waste rock dumps, including a 240 m high in-pit dump: the construction and performance monitoring of a “store and release” cover over potentially acid forming mineralised waste rock; erosion from the side slopes of the waste rock dumps; the in-pit co-disposal of waste rock and thickened tailings; the geotechnical stability of the tailings dam wall; the potential for erosion of bare tailings; the water balance of the tailings dam; direct revegetation of the tailings; and the pit hydrology. The rehabilitation of the mine represents an important benchmark in mine site rehabilitation best practice, from which lessons applicable worldwide can be shared.

Asymmetric blasting: a rock mass dependent blast design method

Blasting has been the most frequently used method for rock breakage since black powder was first used to fragment rocks, more than two hundred years ago. This paper is an attempt to reassess standard design techniques used in blasting by providing an alternative approach to blast design. The new approach has been termed asymmetric blasting. Based on providing real time rock recognition through the capacity of measurement while drilling (MWD) techniques, asymmetric blasting is an approach to deal with rock properties as they occur in nature, i.e., randomly and asymmetrically spatially distributed. It is well accepted that performance of basic mining operations, such as excavation and crushing rely on a broken rock mass which has been pre conditioned by the blast. By pre-conditioned we mean well fragmented, sufficiently loose and with adequate muckpile profile. These muckpile characteristics affect loading and hauling [1]. The influence of blasting does not end there. Under the Mine to Mill paradigm, blasting has a significant leverage on downstream operations such as crushing and milling. There is a body of evidence that blasting affects mineral liberation [2]. Thus, the importance of blasting has increased from simply fragmenting and loosing the rock mass, to a broader role that encompasses many aspects of mining, which affects the cost of the end product. A new approach is proposed in this paper which facilitates this trend 'to treat non-homogeneous media (rock mass) in a non-homogeneous manner (an asymmetrical pattern) in order to achieve an optimal result (in terms of muckpile size distribution).' It is postulated there are no logical reasons (besides the current lack of means to infer rock mass properties in the blind zones of the bench and onsite precedents) for drilling a regular blast pattern over a rock mass that is inherently heterogeneous. Real and theoretical examples of such a method are presented.

Critical comparison of Julius Kruttschnitt Mineral Research Centre (JKMRC) blast fragmentation models

Blast fragmentation can have a significant impact on the profitability of a mine. An optimum run of mine (ROM) size distribution is required to maximise the performance of downstream processes. If this fragmentation size distribution can be modelled and controlled, the operation will have made a significant advancement towards improving its performance. Blast fragmentation modelling is an important step in Mine to Mill™ optimisation. It allows the estimation of blast fragmentation distributions for a number of different rock mass, blast geometry, and explosive parameters. These distributions can then be modelled in downstream mining and milling processes to determine the optimum blast design. When a blast hole is detonated rock breakage occurs in two different stress regions - compressive and tensile. In the-first region, compressive stress waves form a 'crushed zone' directly adjacent to the blast hole. The second region, termed the 'cracked zone', occurs outside the crush one. The widely used Kuz-Ram model does not recognise these two blast regions. In the Kuz-Ram model the mean fragment size from the blast is approximated and is then used to estimate the remaining size distribution. Experience has shown that this model predicts the coarse end reasonably accurately, but it can significantly underestimate the amount of fines generated. As part of the Australian Mineral Industries Research Association (AMIRA) P483A Mine to Mill™ project, the Two-Component Model (TCM) and Crush Zone Model (CZM), developed by the Julius Kruttschnitt Mineral Research Centre (JKMRC), were compared and evaluated to measured ROM fragmentation distributions. An important criteria for this comparison was the variation of model results from measured ROM in the-fine to intermediate section (1-100 mm) of the fragmentation curve. This region of the distribution is important for Mine to Mill™ optimisation. The comparison of modelled and Split ROM fragmentation distributions has been conducted in harder ores (UCS greater than 80 MPa). Further work involves modelling softer ores. The comparisons will be continued with future site surveys to increase confidence in the comparison of the CZM and TCM to Split results. Stochastic fragmentation modelling will then be conducted to take into account variation of input parameters. A window of possible fragmentation distributions can be compared to those obtained by Split . Following this work, an improved fragmentation model will be developed in response to these findings.