Prevention of Water Inrushes in Deep Coal Mining over the Ordovician Aquifer: A Case Study in the Wutongzhuang Coal Mine of China

Through field observation and theoretical study, we found that the Hanxing mining area has a typical ternary structure in coal mining under high water pressure of the aquifer. This ternary structure is the Ordovician limestone aquifer-aquiclude including thin limestones-coal seam. Although the aquiclude is considerably thick, there is still a great risk of water burst during mining under water pressure in the deep burial environment. Multidimensional characteristics of floor water inrush in deep mining are summarized in the paper, including water migration upwardly driven by the Ordovician confined water, the planar dispersion of the water inrush channel, the stepped increase of the water inrush intensity, the hysteretic effluent of the water inrush time and the exchange, and adsorption of the water quality. The water inrush mechanism is clarified that the permeability, dilatancy, fracturing, and ascending of the water from the Ordovician limestone aquifer form a planar and divergent flow through the transfer, storage, and transportation of thin limestone aquifers. The corresponding water inrush risk evaluation equation is also proposed. Based on the thickness of the aquiclude, the thickness of the failure zones, and the water inrush coefficient, the floor aquiclude is classified into five categories. While water inrush cannot be completely controlled by the traditional underground floor reinforcement with ultra-thick aquiclude or even zonal grouting, a comprehensive prevention and control concept of the four-dimensional floor water hazard in full time-space domain are proposed. A tridimensional prevention and control model of three-dimensional reticulated exploration, treatment, verification, and supplementation is presented. A full time domain technological quality control process of condition assessment, exploration, remediation, inspection, evaluation, monitoring, and reassurance is formed, and a water disaster prevention method with full time-space tridimensional network in deep coal mining is established. Case study in the Hanxing mining area demonstrates that the proposed methods are highly effective.

OEDIPUS PLOT: PARADOXES OF IDENTIFICATION

This article deals with the plot structure of the Oedipus myth. From the set of known sources we select a series of elements that form a plot representing an object of our analysis. The author takes into account the following elements: 1) piercing of Oedipus’s ankles and the subsequent displacement of Oedipus to the mountain Cithaeron, 2) the deadly clash between Oedipus and Laius, 3) the riddle of the Sphinx and the Oedipus’s answer, 4) the suicide of the Sphinx, 5) the accession of Oedipus to the throne in Thebes, 6) Oedipus’s discovery of his own origins, 7) the suicide of Jocasta, 8) the self-blinding of Oedipus. In the plot there is a series of correspondences related to the number 3. In the riddle of the Sphinx that Oedipus solves, 3 stages of human life are indicated: infancy, maturity, old age. In the Sphinx, 3 components are integrated in one whole: “man + lion + bird”. Oedipus commits murder in the point where 3 roads meet. It is shown that incest and clash with the unrecognized father are expressed in the myth in the framework of such a ternary structure. The relevant elements that normally are separated from each other, merge in one point that is nothing else than a singular transformation. The other cases consist in mapping a common human history (that is continual by its very meaning) to a discrete sequence of three phases in an individual story of Oedipus. We also discuss some aspects of the Sphinx riddle that were not given a proper attention before. The feature with respect to which different stages of human life are classified, is related to legs. In turn, this motif is correlated with the presence or absence of footing. Deprivation of it is acts as a source of danger. In turn, this motif is correlated with the presence or absence of footing. Deprivation of it is acts as a source of danger. Both the contents of the riddle and the process of asking and guessing can be correlated with further investigation carried out by Oedipus.

ANTHROPOLOGY OF EVALUATION: THE ‘MACABRE CONSTANT’

The author suggests, arguing from the work of Antibi (2003) that there is an inherent bias in assessment, the macabre constant. It is argued that there is a tendency for markers to create categories of assessment and balance the numbers between these irrespective of pupils / students’ actual performance. Teachers know that if all their students have good grades on a regular basis they will be considered too ‘nice’; conversely, if they consistently give marks below average, they will be considered too “strict”. A ‘good’ assessment thus divides the class into three groups: the ‘good’, the ‘average’ and the ‘bad’. Some students will certainly move to an adjacent group, but the ternary structure will remain. About a third of students are thus condemned to failure regardless of educational conditions: whatever the level of the class, the quality of teaching, the subjects taught, failure will happen. No proposal has so far succeeded in really improving the situation: failure remains. The reason is that all evaluations are finally caught up by the macabre constant. For a significant change to really take place, it is argued that the process of assessment must take account of the central role of the macabre constant.

Ternary structure of the outer membrane transporter FoxA with resolved signalling domain provides insights into TonB-mediated siderophore uptake

Many microbes and fungi acquire the essential ion Fe3+ through the synthesis and secretion of high-affinity chelators termed siderophores. In Gram-negative bacteria, these ferric-siderophore complexes are actively taken up using highly specific TonB-dependent transporters (TBDTs) located in the outer bacterial membrane (OM). However, the detailed mechanism of how the inner-membrane protein TonB connects to the transporters in the OM as well as the interplay between siderophore- and TonB-binding to the transporter is still poorly understood. Here, we present three crystal structures of the TBDT FoxA from Pseudomonas aeruginosa (containing a signalling domain) in complex with the siderophore ferrioxamine B and TonB and combine them with a detailed analysis of binding constants. The structures show that both siderophore and TonB-binding is required to form a translocation-competent state of the FoxA transporter in a two-step TonB-binding mechanism. The complex structure also indicates how TonB-binding influences the orientation of the signalling domain.