Salt diffusion and distribution in meat studied by Na-23 nuclear magnetic resonance imaging and relaxometry

This study introduces the use of combined Na-23 magnetic resonance imaging (MRI) and Na-23 NMR relaxometry for the study of meat curing. The diffusion of sodium ions into the meat was measured using Na-23 MRI on a 1 kg meat sample brined in 10% w/w NaCl for 3-100 h. Calculations revealed a diffusion coefficient of 1 x 10(-5) cm(2)/s after 3 h of curing and subsequently decreasing to 8 x 10(-6) cm(2)/s at longer curing times, suggesting that changes occur in the microscopic structure of the meat during curing. The microscopic mobility and distribution of sodium was measured using Na-23 relaxometry. Two sodium populations were observed, and with increasing length of curing time the relaxation times of these changed, reflecting a salt-induced swelling and increase in myofibrillar pore sizes. Accordingly, the present study demonstrated that pore size and thereby salt-induced swelling in meat can be assessed using Na-23 relaxometry.

The effects of temperature and salinity on Acacia harpophylla (brigalow) (Mimosaceae) germination

Acacia harpophylla F. Muell. (brigalow) used to naturally occur over a range of about 50 000 km(2) in Queensland and New South Wales, Australia. Large scale clearing for agriculture has reduced the area to less than 20 000 km(2) and it is estimated that 20-25% of vertebrate fauna living in brigalow communities will become locally extinct as a result of the current clearing induced loss of habitat. Some coal mining companies in central Queensland have become interested in providing habitat for the endangered bridle nail-tailed wallaby that lives in brigalow vegetation. However, there is little known about establishment techniques for brigalow on mine sites and other disturbed ground; an understanding of brigalow biology and ecology is required to assist in the conservation of this threatened vegetation community and for re-creation of bridled nail-tail wallaby habitat in the post mining landscape. Brigalow is an unusual species of Acacia because it is not hard-seeded and germinates readily without the need to break seed-coat imposed dormancy. Germination trials were undertaken to test the ability of brigalow seed to germinate with a range of temperatures and salinity levels similar to those experienced in coal mine spoil. Optimum germination was found to occur at temperatures from 15 to 38 degrees C and no germination was recorded at 45 degrees C. Brigalow was very tolerant of high salt levels and germinated at percentages greater than 50% up to the highest salinity tested, 30 dS/m. Germination of greater than 90% occurred up to an electrical conductivity of 20 dS/m. The results indicate brigalow seed can be sown in summer when rains are most likely to occur, however, shading of the seed with extra soil or mulch may ensure the ground surface does not become too hot for germination. Because of its ability to germinate at high salinity levels, brigalow may be suitable for use in saline mine wastes which are common on sites to be rehabilitated after mining.

The influence of coating materials on some properties of alginate beads and survivability of microencapsulated probiotic bacteria

The probiotics, Lactobacillus acidophilus 547, Bifidobacterium bifidum ATCC 1994, and Lactobacillus casei 01, were encapsulated into uncoated calcium alginate beads and the same beads were coated with three types of material, chitosan, sodium alginate, and poly-L-lysine in combination with alginate. The thickness of the alginate beads increased with the addition of coating materials. No differences were detectable in the bead strength by texture analysis or in the thickness of the beads with different types of coating materials by transmission electron microscopy. The survivability of three probiotics in uncoated beads, coated beads, and as free cells (unencapsulated) was conducted in 0.6% bile salt solution and simulated gastric juice (pH 1.55) followed by incubation in simulated intestinal juice with and without 0.6% bile salt. Chitosan-coated alginate beads provided the best protection for L. acidophilus and L. casei in all treatments. However, B. bifidum did not survive the acidic conditions of gastric juice even when encapsulated in coated heads. (C) 2004 Elsevier Ltd. All rights reserved.

Assessing longwall support-roof interaction from shield leg pressure data

A concept has been developed where characteristic load cycles of longwall shields can describe most of the interaction between a longwall support and the roof. A characteristic load cycle is the change in support pressure with time from setting the support against the roof to the next release and movement of the support. The concept has been validated through the back-analysis of more than 500 000 individual load cycles in five longwall panels at four mines and seven geotechnical domains. The validation process depended upon the development of new software capable of both handling the large quantity of data emanating from a modern longwall and accurately delineating load cycles. Existing software was found not to be capable of delineating load cycles to a sufficient accuracy. Load-cycle analysis can now be used quantitatively to assess the adequacy of support capacity and the appropriateness of set pressure for the conditions under which a longwall is being operated. When linked to a description of geotechnical conditions, this has allowed the development of a database for support selection for greenfield sites. For existing sites, the load-cycle characteristic concept allows for a diagnosis of strata-support problem areas, enabling changes to be made to set pressure and mining strategies to manage better, or avoid, strata control problems. With further development of the software, there is the prospect of developing a system that is able to respond to changes in strata-support interaction in real time.

Revegetation strategies for bauxite refinery residue: A case study of Alcan Gove in Northern Territory, Australia

Alumina extraction from bauxite ore with strong alkali produces waste bauxite refinery residue consisting of residue sand and red mud. The amount and composition of refinery residue depend on the purity of the bauxite ore and extraction conditions, and differs between refineries. The refinery residue is usually stored in engineered disposal areas that eventually have to be revegetated. This is challenging because of the alkaline and sodic nature of the residue. At Alcan Gove's bauxite refinery in Gove, Northern Territory, Australia, research into revegetation of bauxite residue has been conducted since the mid-1970s. In this review, we discuss approaches taken by Alcan Gove to achieve revegetation outcomes (soil capping of refinery residue) on wet-slurry disposal areas. Problems encountered in the past include poor drainage and water logging during the wet season, and salt scalding and capillary rise during the dry season. The amount of available water in the soil capping is the most important determinant of vegetation survival in the seasonally dry climate. Vegetation cover was found to prevent deterioration of the soil cover by minimising capillary rise of alkalinity from the refinery residue. The sodicity and alkalinity of the residue in old impoundments has diminished slightly over the 25 years since it was deposited. However, development of a blocky structure in red mud, presumably due to desiccation, allows root penetration, thereby supplying additional water to salt and alkali-tolerant plant species. This has led to the establishment of an ecosystem that approaches a native woodland.

Evaluation by respirometry of the degradability of retort water using a shale ash and overburden packed column

Oil shale processing produces an aqueous wastewater stream known as retort water. The fate of the organic content of retort water from the Stuart oil shale project (Gladstone, Queensland) is examined in a proposed packed bed treatment system consisting of a 1:1 mixture of residual shale from the retorting process and mining overburden. The retort water had a neutral pH and an average unfiltered TOC of 2,900 mg l(-1). The inorganic composition of the retort water was dominated by NH4+. Only 40% of the total organic carbon (TOC) in the retort water was identifiable, and this was dominated by carboxylic acids. In addition to monitoring influent and effluent TOC concentrations, CO2 evolution was monitored on line by continuous measurements of headspace concentrations and air flow rates. The column was run for 64 days before it blocked and was dismantled for analysis. Over 98% of the TOC was removed from the retort water. Respirometry measurements were confounded by CO2 production from inorganic sources. Based on predictions with the chemical equilibrium package PHREEQE, approximately 15% of the total CO2 production arose from the reaction of NH4+ with carbonates. The balance of the CO2 production accounted for at least 80% of the carbon removed from the retort water. Direct measurements of solid organic carbon showed that approximately 20% of the influent carbon was held-up in the top 20cm of the column. Less than 20% of this held-up carbon was present as either biomass or as adsorbed species. Therefore, the column was ultimately blocked by either extracellular polymeric substances or by a sludge that had precipitated out of the retort water.

Wills' mineral processing technology: an introduction to the practical aspects of ore treatment and mineral recovery

"Wills' Mineral Processing Technology" provides practising engineers and students of mineral processing, metallurgy and mining with a review of all of the common ore-processing techniques utilized in modern processing installations. Now in its Seventh Edition, this renowned book is a standard reference for the mineral processing industry. Chapters deal with each of the major processing techniques, and coverage includes the latest technical developments in the processing of increasingly complex refractory ores, new equipment and process routes. This new edition has been prepared by the prestigious J K Minerals Research Centre of Australia, which contributes its world-class expertise and ensures that this will continue to be the book of choice for professionals and students in this field. This latest edition highlights the developments and the challenges facing the mineral processor, particularly with regard to the environmental problems posed in improving the efficiency of the existing processes and also in dealing with the waste created. The work is fully indexed and referenced. -The classic mineral processing text, revised and updated by a prestigious new team -Provides a clear exposition of the principles and practice of mineral processing, with examples taken from practice -Covers the latest technological developments and highlights the challenges facing the mineral processor -New sections on environmental problems, improving the efficiency of existing processes and dealing with waste.