Experimental Study of Pore Permeability Characteristics Based On Variable-Mass System In Karst Collapse Pillars

Particle loss is the root cause for the occurrence of Karst Collapse Pillars (KCP) sudden water events. The pore adjustment of KCP filler will further induce seepage destabilization, and it is also a process that sudden water catastrophe must go through. In order to investigate the direct relationship between stress conditions, water pressure conditions, and gradation structure on the pore structure of rock samples, the steady-state percolation method was used to investigate the percolation test system of variable-mass crushed rock masses. The results show that: 1) the structural characteristics of rock grains under the same stress environment are closely related to their extrusion fragmentation process and the softening and scouring effect of water. Rubbing, rotating, fracturing, grinding and plugging are the main forms of action of their intergranular action. 2) The filling particles before and after the loss meet the fractal law and have fractal characteristics. 3) The percentage of fine particles in the whole process of infiltration loss is as high as 34.4%. The adjustment of pore structure is related to the particle size gradation, and the reciprocal action of water flow will form a stable water-conducting channel. 4) The sudden water process of the specimen under particle loss can be divided into three stages: initial seepage, catastrophic destabilization and pipe flow surge.

Author Correction: Systematic evaluation of particle loss during handling in the percutaneous transluminal angioplasty for eight different drug-coated balloons

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Comparing energetic particle loss processes in the magnetospheres of Jupiter and Saturn using Energetic Neutral Atom (ENA) remote sensing

<p>The dedicated Energetic Neutral Atom (ENA) imager on the Cassini spacecraft provided indispensable measurements of magnetospheric processes at Saturn. At Jupiter, Cassini provided only a few serendipitous ENA images as the spacecraft flew by Jupiter at large radial distances.  The Juno spacecraft, now in a polar orbit around Jupiter, carries no ENA camera, but the energetic particle JEDI instrument is sensitive to ENA’s with energies > 50 keV, provided there are few charged particles in the environment to mask their presence.  Even with limited ENA capabilities, the Juno mission has revealed important differences between Saturn and Jupiter with regard to how charged ions are lost from these magnetospheric systems. Specifically, a major contribution to ENA emissions at Jupiter come from Jupiter’s polar atmosphere. These ENAs likely arise from energetic ions that nearly precipitate in the auroral zone, only to mirror magnetically within the atmosphere where they charge exchange with atoms in Jupiter’s upper atmosphere. Cassini did not observe this precipitating component at Saturn despite the abundance of quality ENA measurements obtained there. We conclude that ion precipitation into Jupiter’s atmosphere is competitive with other loss processes.  In contrast, in the Saturn system, it is likely that losses associated with the dense neutral gas populations near the equator dominate the loss of energetic particles.</p>

Fates and spatial variations of accumulation mode particles in a multi-zone indoor environment during the HOMEChem campaign

We report on significant spatial gradients of accumulation mode particles emitted during the HOMEChem campaign and assess particle loss pathways.

A base-line study of the wear of burs used for chairside milling of ceramic crowns of different hardness: effect on internal fit and surface roughness

INTRODUCTION: Wear of milling burs may affect the internal fit and surface roughness of the milled crown. AIM: To assess the wear of diamond and tungsten carbide (TC) burs from milling ceramic materials and the effect on internal fit and surface roughness. METHODS: Thirty crowns of each of the two materials were milled from the same standard preparation. Diamond burs were used for a feldspathic ceramic and TC burs for zirconia. Before and after the 10th, 20th and 30th milling, diamond particle loss was counted and cutting blade changes of the TC burs measured. Internal fit was measured using a silicone replica technique and surface roughness by 3D laser microscope. RESULTS: An average 26% loss of diamond particles occurred after 30 crowns, resulting in a 6% decrease in internal luting space and a 21% decrease in surface roughness. Wear of the TC burs resulted in a 13% decrease in the luting space, and a 16% increase in surface roughness. CONCLUSION: The wear of milling burs reduces the luting space, and the milling parameters must be adjusted to compensate for this. Surface roughness is affected by bur type: with diamond burs it decreased, and increased with TC burs.