An Experimental Study of the Water Transfer Through Confined Compacted GMZ Bentonite

International audienceGMZ bentonite has been considered as a possible material for engineered barrier in the Chinese program of nuclear waste disposal at great depth. In the present work, the hydraulic conductivity of this bentonite was determined by simultaneous profile method. A specific infiltration cell equipped with five resistive relative humidity probes was designed for this purpose. The water retention properties were studied under both confined and unconfined conditions; the results shows that at high suctions (> 4 MPa) the water retention capacity is independent of the confining condition, and by contrast, at low suctions (< 4MPa) the confined condition resulted in significant low water retention. Furthermore, the microstructure was investigated at Mercury Intrusion Porosimetry (MIP) and Environmental Scanning Electron Microscope (ESEM) in different states: on oven-dried powder, bentonite slurry, as-compacted and wetted samples. It has been observed that the soil powder is constituted of aggregates of various sizes; this aggregates are destroyed by fully saturation at a water content equal to the liquid limit; compaction at the initial water content of 11-12% and a dry density of 1.7 – 1.75 Mg/m3 led to a microstructure characterized by an dense assembly of relatively well preserved aggregates; saturation of the compacted sample under constant volume condition defined a non-homogeneous microstructure with the presence of well preserved aggregates. This non-homogeneous microstructure would be due to the non uniform distribution of the generated swelling pressure within the soil sample upon wetting. The hydraulic conductivity determined has been found decreasing firstly and then increasing with suction decrease from the initial value of about 80 MPa to zero; the decrease can be attributed to the large pore clogging due to soft gel creation by exfoliation process, as observed at ESEM

17βH-Periplogenin, a cardiac aglycone from the root bark of Periploca sepium Bunge

The title compound {systematic name: 4-[(3S,5S,8R,9S,10R,13R,14S,17S)-3,5,14-trihy­droxy-10,13-dimethyl­hexa­deca­hydro-1H-cyclo­penta­[a]phenanthren-17-yl]furan-2(5H)-one}, C23H34O5, was isolated from the roots of Periploca sepium Bunge, a famous Chinese traditional herbal medicine. The three six-membered rings adopt chair conformations, the cyclo­pentane ring displays an approximate envelope conformation (with the C atom bearing the methyl substituent at the flap) and the five-membered lactone ring adopts an essentially planar [maximum deviation of 0.004 (8) Å] conformation. In the crystal, mol­ecules are linked into helical chains along [010] by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions. Two intra­molecular O—H⋯O hydrogen bonds are also present

The uncertainty evaluation method of supply chain reliability

The objective of the article is to scientifically evaluate supply chain reliability (SCR). We argue that this problem relates to two aspects ‐ the cognition and expression of SCR. The paper considers SCR as a unification of a fuzzy and random meaning in a dynamic environment. Furthermore, intrinsic relationship between the theoretical foundation of SCR evaluation and the cloud theory is discovered, accordingly to which, the cloud theory is applied to study the evaluation of SCR from a holistic perspective. According to the comprehensive invalidation degree of a supply chain, SCR is differentiated as six grades and the influencing factors of SCR are classified taking into account __ve aspects. A comprehensive performance model is developed to measure five aspects of influencing factors and to evaluate the exact class SCR belongs to. As we know, the cognition of SCR depends on human mind while the natural language is an appropriate medium to express human mind. Therefore, linguistic terms are adopted to express uncertain transformation between qualitative concepts and their corresponding quantitative values. This method is further demonstrated using a numerical example. First published online: 27 Oct 201