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BACKGROUND Porosity is a key parameter for exploration and evaluation of shale gas reservoirs. Rapid and accurate determination of shale porosity is crucial for reserve calculation. At present, there are helium gas method, liquid saturation method and image analysis method applied to shale porosity determination, but the comparison between methods and laboratories is lacking. OBJECTIVES To evaluate the applicability of different methods for determining shale porosity. METHODS The characteristics of 69 shale samples from the Longmaxi Formation were studied by analyzing and testing techniques such as X-ray diffraction, argon ion polishing-scanning electron microscopy, and mercury injection-nitrogen adsorption method. Comparison experiments for porosity measurement were conducted among helium method, liquid saturation method and image analysis method. RESULTS The Longmaxi Formation shale had high clay content, many organic pores, small pore throats, and poor seepage capacity, which made it difficult for foreign liquids and gases to quickly enter the pores, which required high resolution of core image data. The liquid saturation method (alcohol method) used 20MPa pressure to saturate the sample for 24 hours, resulting in core damage, and the measured porosity deviated from the true value. The image analysis method ignored the micropores (pore size < 2nm) and mesopores (pore size < 50nm) in the mineral matrix and other factors, making the porosity measurement result unreliable. The porosity measurement result of the helium method was closely related to the drying temperature and stabilization time. The higher the temperature, the larger the measured porosity, and if the stabilization time is too short, the porosity result will be smaller than the real values. CONCLUSIONS After drying the core at 60℃ for more than 24 hours to a constant weight, by setting a reasonable stabilization time, accurate porosity results can be obtained by the helium method. Properly increasing the injection pressure helps to speed up the experimentation rate.

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The quasi-geostrophic (QG) equations play a crucial role in our understanding of atmospheric and oceanic fluid dynamics. Nevertheless, the traditional QG equations describe 'dry' dynamics that do not account for moisture and clouds. To move beyond the dry setting, precipitating QG (PQG) equations have been derived recently using formal asymptotics. Here, we investigate whether the moist Boussinesq equations with phase changes will converge to the PQG equations. A priori , it is possible that the nonlinearity at the phase interface (cloud edge) may complicate convergence. A numerical investigation of convergence or non-convergence is presented here. The numerical simulations consider cases of [Formula: see text], 0.01 and 0.001, where [Formula: see text] is proportional to the Rossby and Froude numbers. In the numerical simulations, the magnitude of vertical velocity [Formula: see text] (or other measures of imbalance and inertio-gravity waves) is seen to be approximately proportional to [Formula: see text] as [Formula: see text] decreases, which suggests convergence to PQG dynamics. These measures are quantified at a fixed time [Formula: see text] that is [Formula: see text], and the numerical data also suggests the possibility of convergence at later times. This article is part of the theme issue 'Mathematical problems in physical fluid dynamics (part 2)'.

Long noncoding RNAs (lncRNAs) play a crucial role in progression of bladder urothelial carcinoma (BUC). However, the molecular mechanisms behind this role have not been elucidated yet. Here, we found that the lncRNA MAFG-AS1, which is highly expressed in BUC, is correlated with aggressive characteristics and poor prognosis of BUC. We demonstrate that MAFG-AS1 can promote BUC proliferation, invasion, metastasis, and epithelial-mesenchymal transition in vitro and in vivo. Mechanistically, MAFG-AS1 direct binding to Hu antigen R (HuR) could recruit ubiquitin-specific proteinase 5 (USP5) to prevent HuR from degrading by ubiquitination. We further demonstrate that overexpression of MAFG-AS1 can upregulate the expression of polypyrimidine tract-binding protein 1 (PTBP1) through promoting its stability mediated by bound HuR. In conclusion, these findings indicate that MAFG-AS1 promotes the progression of BUC via regulation of the HUR/PTBP1 axis. Targeting MAFG-AS1 may provide a novel strategy for individualized therapy and a potential biomarker for prognosis of BUC., (© 2020 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Long non-coding RNAs (lncRNAs) play a vital role in the progression of several cancers, including nasopharyngeal carcinoma (NPC). However, the mechanism of lncRNA involvement in the progression of NPC remains to be elucidated. Hence, we conducted in vivo and in vitro experiments to determine the molecular mechanism of FOXD1-AS1. We found that FOXD1-AS1 was over-expressed in NPC cells and tissues, and was significantly associated with poor survival rate in patients with NPC. We also found that FOXD1-AS1 promotes cellular proliferation, migration, invasion, and glycolysis, and inhibits apoptosis by upregulating the expression of FOXD1. Furthermore, FOXD1 could transcriptionally up-regulate the expression of key glycolytic genes to promote the glycolysis levels of NPC. The identified FOXD1-AS1 may serve as a potential prognostic biomarker and therapeutic target for patients with NPC., Competing Interests: None., (AJCR Copyright © 2020.)

Accurately determining the adsorbed amount of CH 4 on shale is significant for understanding the mechanisms of shale gas storage and shale methane recovery from shale gas reservoirs. Excess CH 4 adsorption is measured using the thermogravimetric method. Simplified local density (SLD) theory is applied to calculate the adsorbed CH 4 density to obtain the absolute adsorption. Moreover, the modified Langmuir adsorption model is employed to fit the excess adsorption to describe the absolute adsorption. The adsorbed CH 4 density from the SLD model is affected by the system pressure and temperature, while such density obtained from the modified Langmuir model is only a function of temperature. Compared to the modified Langmuir model, the SLD model can better capture the adsorbed CH 4 density, which allows accurate determination of the absolute CH 4 adsorption., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)