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.

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.

Nutrient deficiencies in greater yam and their effects on leaf nutrient concentrations

This paper describes the first systematic study of nutritional deficiencies of greater yam (Dioscorea alata). Yam plants (cv. 'Mahoa'a') were propagated from tuber discs and grown in nutrient solution, with nutrients supplied following a modified programmed nutrient-addition method. After an establishment period of four weeks, deficiencies of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), boron (B), manganese (Mn), copper (Cu), zinc (Zn), and molybdenum (Mo) were induced by omitting the relevant nutrient from the solution. Foliar symptoms were recorded photographically. Notably, deficiencies of the mobile macronutrients failed to induce senescence of oldest leaves, while vine growth and younger leaves were affected. Leaf blades of the main stem were sampled in sequence and analyzed chemically, providing the distribution of each nutrient from youngest to oldest leaves in both adequately supplied and deficient plants. The nutrient-concentration profiles, together with the visible symptoms, indicated that little remobilization of mobile macronutrients had occurred. For both macro- and micronutrients, young leaves gave the best separation of nutrient concentrations between well-nourished and deficient plants.

Diagnosis and Correction of Nutritional Disorders in Ginger

This booklet contains descriptions and photographs of symptoms of deficiencies and toxicities of nutrients, including nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, boron, manganese, zinc, copper and molybdenum, and advice on treatment of affected crops.

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.

The creep properties of a series of zinc-rich zinc-aluminium alloys

The compressive creep behaviour of six sand cast zinc-rich alloys: No3 and No5, corresponding to BS 1004A and BS 1004B, respectively, alloy No2, ILZRO,.16 and two newer alloys ACuZinc5 and ACuZinc10 was investigated. The total creep contraction of the alloys was found to be well correlated using an empirical equation. On the basis of this equation, a parametrical relationship was derived which allowed the total creep contraction to be related to the applied stress, the temperature and the time of test, so that a quantitative assessment of compressive creep of the alloys could be made under different testing conditions. The primary creep and secondary creep rates were found for the alloys at different temperatures and stresses. Generally, the primary creep contraction was found to increase with copper content, whereas secondary creep rates decreased in the order No3, ACuZinc10, ACuZinc5 and No2. ILZRO.16 was tested only at the highest stress and two higher temperatures. The results showed that ILZRO.16 had higher creep resistance than all the other alloys. Thus, based on the above empirical equation, alloy No2 was found to have a substantially better total creep resistance than alloys No3 and No5, and slightly better than ACuZinc5 and ACuZinc10 for strains up to 1%. Both ACuZinc alloys had higher creep strength than commercial alloys No3 and No5. Alloy No5 had much higher creep resistance than alloy No3 under all conditions. The superior creep resistance of alloy No2 was considered to be due to the presence of small precipitates of -phase in the zinc matrix and a regular eutectic morphology. The stress exponents and activation energies for creep under different testing conditions were found to be consistent with some established creep-controlling mechanisms; i.e. dislocation climb for alloy No3, dislocation climb over second phase particles for alloys No5, No2, ACuZinc10, controlled by lattice diffusion in the zinc-rich phase. The lower creep resistance of alloy No3 was mainly due to the lower creep strength of copper-free primary particles having greater volume than eutectic in the microstructure. Alloys No5, ACuZinc5 and ACuZinc10 showed much better creep resistance than alloy No3, based on the precipitation-hardening due to the presence of small -phase precipitates. The primary dendrites in both ACuZinc alloys however were not of much benefit in improving the creep resistance of the alloys.

The influence of environment on foliose lichen growth and its biological significance

Radial growth and growth in mass of lichens is influenced by climatic and microclimatic factors and also by substratum factors such as rock and bark texture, chemistry, and nutrient enrichment. Seasonal fluctuations in growth, as measured by radial growth rate (RaGR) per month, often correlate best with average or total rainfall, the number of rain days, or rainfall in a specific season. Temperature is also considered to be an important climatic factor in some studies. Interactions between microclimatic factors and especially light intensity, temperature, and moisture are the most important in determining local annual growth rates. The physical and chemical nature of the substratum has a profound influence on the growth of foliose lichens. Hence, the effects of texture, porosity, rate of drying, and the physical changes of the substratum on growth are likely to influence lichen distributions. Bird droppings may influence growth and survival by smothering the thalli, altering the pH, or adding inhibitory and stimulatory compounds. Nitrogen and phosphate availability may also influence growth. Chemical factors may also have an important influence on lichens of maritime rocks, the effect of salinity and calcium ions being of particular importance. Zinc, copper, and mercury may also be important in lichen growth as they have been shown to affect the chlorophyll content of lichen algae. Effects of environmental factors on growth influence the competitive ability of lichens thus influencing their ecology and distribution.

A computational approach to measuring the correlation between expertise and social media influence for celebrities on microblogs

Existing approaches of social influence analysis usually focus on how to develop effective algorithms to quantize users' influence scores. They rarely consider a person's expertise levels which are arguably important to influence measures. In this paper, we propose a computational approach to measuring the correlation between expertise and social media influence, and we take a new perspective to understand social media influence by incorporating expertise into influence analysis. We carefully constructed a large dataset of 13,684 Chinese celebrities from Sina Weibo (literally 'Sina microblogging'). We found that there is a strong correlation between expertise levels and social media influence scores. In addition, different expertise levels showed influence variation patterns: high-expertise celebrities have stronger influence on the 'audience' in their expertise domains.

The relationship of thymulin activity, immune parameters of HIV disease progression and substance use in a cohort of HIV seropositive alcohol and drug users

Zinc is essential for the activity of thymulin, a thymic hormone involved in T-lymphocyte differentiation and activation. Zinc deficiency is widespread in populations with HIV infection, and HIV+ drug users are particularly susceptible to zinc deficiency and immune suppression. This dissertation explored the relationship of zinc-bound active thymulin to plasma zinc, CD4+ and CD8+ cell count, the CD4+/CD8+ ratio, and drug use in HIV-infected drug users. Zinc-bound active thymulin was assessed in plasma of HIV+ drug users who were participating in a 30 month zinc supplementation trial. Plasma from 80 participants at the 12 month visit, and 40 of these same participants, randomly selected, at the baseline visit were assessed for zinc-bound active thymulin levels using a modification of the rosette inhibition assay. Thymulin activity was directly associated with CD4+ cell count (β = 0.127, p = 0.002) and inversely associated with cocaine use (β = −0.908, p = 0.026; R2 = 0.188, p = 0.019) independent of HIV viral load, age, gender and antiretroviral use. An increase in thymulin activity was 1.4 times more likely when CD4+ cell count increased (OR = 1.402, 95%CI: 1.006–1.956), independent of change in viral load, antiretroviral use, and age. Participants who used cocaine consistently, were 7.6 times less likely to have an increase in thymulin activity (OR = 0.133, 95%CI: 0.017–1.061). There was a direct correlation between change in plasma zinc and change in zinc-bound active thymulin (r = 0.243, p = 0.13). Analysis of CD4+ cell count decline in 222 participants in the zinc supplementation trial across the 30 months showed that both crack cocaine use and heavy alcohol use accelerated CD4+ cell count decline. Thymulin activity is directly associated with HIV disease progression, measured by CD4+ cell count, and is depressed with cocaine use independent of antiretroviral use and HIV viral load. Cocaine and heavy alcohol accelerate CD4+ cell count decline. The effect of cocaine on thymic output requires further evaluation as a mechanism for the association of cocaine use with faster HIV disease progression.

Castles in the air: the life, times and influence of the Reverend Moses Harvey (1820-1901).

The period from 1874 to 1901 was a time of significant transition in the economic and political life of Newfoundland. Twenty years into responsible government and with Confederation on the backburner, the colony’s politicians turned their attention to economic diversification, landward development and carving out the island’s place in the British Empire. The period saw both economic prosperity and retrenchment; the construction of a trans-insular railway; the adoption of policies to foster agriculture, forestry, manufacturing and mining; and diplomatic efforts to resolve France’s outstanding claims on the northwest coast of the island. At the same time, the government made an attempt to intervene directly in its primary industry, the fisheries. It created a Fisheries Commission in 1889 that recommended conservation measures and artificial propagation as ways to restore the health of some of the island’s fish stocks. They also proposed new methods of curing, packaging and marketing Newfoundland’s cod, as well as a complete overhaul of the truck system. A major player in both the public and private debates surrounding all of these subjects was the Reverend Moses Harvey. Along with being minister of the Free Church of Scotland in St. John’s, Harvey was one of Newfoundland’s most active promoters in the late nineteenth century. He served as the media mouthpiece for both Prime Minister William Whiteway and Prime Minister Robert Thorburn; editing the Evening Mercury – the official organ of the Liberal Party and then the Reform Party – from 1882 to 1883 and 1885 until 1890. As well, Harvey wrote regular columns on Newfoundland issues for newspapers in London, New York, Boston, Montreal, Toronto, and Halifax. He also produced numerous books, articles, encyclopedia entries, and travel guides outlining the island’s attractions and its vast economic potential. In short, Harvey made a significant contribution in shaping the way residents and the outside world viewed Newfoundland during this period. This thesis examines late nineteenth-century Newfoundland through the writing of Moses Harvey. The biographical approach offers a fuller, more nuanced account of some of the major historical themes of the period including the politics of progress, opening up the interior, railway construction and attitudes toward the fisheries. It also provides an insider’s prospective on what led to some of the major political decisions, policy positions or compromises taken by the Whiteway and Thorburn governments. Finally, a more detailed review of Harvey’s work exposes the practical and political differences that he had with people like D.W. Prowse and Bishop Michael Howley. While these so-called “boomers” in Newfoundland’s historiography agreed on broad themes, they parted ways over what should be done with the fisheries and how best to channel the colony’s growing sense of nationalism.

The geological and microbiological controls on the occurrence, mobility and concentration of Se and Te in coal and black shales

© 2016 Institute of Materials, Minerals and Mining and The AusIMM Published by Taylor & Francis on behalf of the Institute and The AusIMM

(Tables 1-3) Silicon dioxide, Corg and trace element concentrations in sediments of the outer Eckernfoerder Bay, Western Baltic Sea

The main question, posed in the work scheme before laboratory analysis was started, was expressed as follows: Do marked seasonal fluctuations occur in trace element content of the sediment surface, and what are the probable influences of factors such as changing hydrographical parameters, plankton sequence etc. ? Special attention was paid to elements known as pollutants, for example mercury. Within this framework samples have been analysed for their contents of manganese, iron, zinc, lead, and mercury. The amounts of silica and organically-bound carbon serve in most cases as reference values for the trace element content. On sand temporary conditions of increased C org content raise the concentrations of all determined elements. Especially the values reached for mercury in July are worth nothing. It is concluded that Zn, Pb, and Hg tend to enrich with respect to C org as the decomposition of organic matter progresses. On mud-sand flocculation and precipitation of Mn/Fe-hydroxides probably represent an additional concentrating factor for the other elements as the relationship of the results for zinc and manganese shows. Manganese may indicate a seasonally related concentrating cycle at the sediment surface.