The Dynamic of Calcium Oxalate (CaOx) in Porang Corms (Amorphophallus muelleri Blume) at Different Harvest Time

The research aims to observe the influence of harvesting time on the change of calcium oxalate (CaOx) content and crystal density in Porang corms. The corms were harvested at different times, i.e., (1) two weeks before the plants shed (R0-1), (2) when the plants shed (R0), and (3) two weeks after the plants shed (R0+1). CaOx was obtained using the modified extracting method. Microscopic observations were obtained from the slices of the edge and center part of porang corms. Parameter observed including CaOx content, corm weight, shape, and density of CaOx crystal. CaOx content and crystal density in corms were analyzed using One way ANOVA. If the results are significant, it will be followed by Tukey Test α 0.05. In the meantime, the relation between CaOx content and corm weight was analyzed using Correlation Test Bivariate. The results showed that CaOx content was relatively higher in porang corms, i.e., 15.98 ± 0.60g/100g. On the other hand, the increasing of CaOx content might improve corm weight. The total density of druse, styloid, and prism crystal was pretty high in corms obtained when the plants shed compared to another harvest time, i.e., 1,494 ± 286; 31,280 ± 17,406 and 6,256 ± 1,533 crystals/cm2 . Raphide crystal density, by contrast, increased in corms obtained after the plants shed, i.e.,1,656 ± 368 crystals/cm2 . Total CaOx crystal density in the edge parts of corms harvested when the plants shed was proportionately higher than in the other harvest times, i.e., 12,292 ± 4,687.89 crystals/cm2 . In contrast, CaOx crystal densities in the center parts of corms were not much different at three harvesting times. The density of druse and prism crystals was somewhat higher in the center part of corms than in the edge parts. In opposition to, the density of raphide and styloid crystals was fairly higher in the edge part of corms than it was in the center parts. However, only raphide crystal density found in the edge and center part of corms was significantly affected by harvest time from all these results

METHODOLOGY FOR CALCULATING THE STRESS STATE OF THE PILLAR FOR THE SALVAGE CHAMBER IN THE PRESENCE OF AN ADJACENT MINED OUT LONGWALL

Analysis of salvage operations at the underground mines of JSC SUEK-Kuzbass has shown that they can have different locations relative to the previously mined out adjacent longwall, which has a significant impact on the duration of salvage operations. If there is a previously mined out adjacent longwall next to the salvage chamber, the duration of salvage operations increases significantly, in contrast to the case when the salvage chamber is located within a pillar, outside the zone affected by the previously mined out longwall. In this regard, the calculation of the stress state of the pillar for the salvage chamber in the presence of an ad-jacent previously mined out longwall is a relevant task. The paper presents a methodology for quantitative assessment of the stress affecting the pillar for the salvage chamber, based on the use of the finite element method. An example of calculating the stress on the pillar for the sal-vage chamber in the presence of an adjacent mined out longwall for specific geological and mining conditions is considered. It has been established that the presence of a previously mined out adjacent longwall causes additional load on the specified pillar. The highest load factors are observed in the edge part of the pillar near the ventilation gateroad.

Substantiation of the method ensuring the safe development of the pit reserves of kimberlite ore deposits in the conditions of the Udachny mine

The paper discusses the features of the development of pit reserves of the Udachnaya diamondiferous pipe which consists of two closely spaced ore bodies under the protection of a moving ore-rock massif (a safety cushion). Low stability of the rock massif located between the ore bodies is indicated. Such low stability is caused by the presence of areas of increased intensity of fracturing and low coherence zones in the massif; it is also caused by the mutual impact of mining operations carried out in closely located ore bodies. A conclusion is made about the danger of collapse of sizeable rock blocks from the edge zones of the rock massif located between the ore bodies onto the safety cushion. In this case, individual rock blocks can be 0.4-0.6 tons or more, the drop height is up to 600-700 m. Impact blows on the safety cushion when rock blocks collapse onto it can cause a disruption of underground mine workings stability and occurrence of dangerous pressure drops at the outlet of air waves from the safety cushion into the underground mine workings. A method for preventing dangerous impact blows is proposed, which consists in the forced collapse (with certain parameters) of the edge part of the rock massif located between the ore bodies, onto the safety cushion.

ON THE CHANGE OF ELASTIC PARAMETERS OF SOILS IN THE SIDES OF COAL CUTS UNDER THE INFLUENCE OF NATURAL AND CLIMATIC FACTORS

The article describes the change in the elastic parameters of soils in the sides of a coal mine during the development of mechanical erosion processes in the marginal part of the Quaternary deposits under the influence of natural and climatic factors. According to the records of seismic vibrations on the profile of the ledge, the limits of the seasonal change in the dynamic modulus of elasticity during freezing of the surface layer of wet soil are determined. An increase of almost 3 times the dynamic Young's modulus is established. The presented results confirm the increase in the activity of natural destruction of soils of the edge part of the sides of the coal mine under the influence of seasonal climatic factors.