Pore Properties in Organic-Rich Shales Derived Using Multiple Fractal Determination Models Applied to Two Indian Permian Basins

In the present study, carbon black activated by CO2 gas was examined through XRD analysis, especially with regard to changes in its structural parameters. Based on the results, its activation process was thoroughly analyzed. The activation process was controlled by isothermally activating the carbon black inside a reaction tube through which CO2 gas flowed. With this approach, the degree of activation was varied as desired. At an early stage of the activation process, the amorphous fraction on the carbon black surface was preferentially activated, and later the less-developed crystalline carbon (LDCC) region inside the carbon black particles started to be activated. The latter process was attributable to the formation of pores inside the carbon black particles. As the activation process proceeded further, the more-developed crystalline carbon (MDCC) region started to be activated, thereby causing the pores inside the carbon black particles to grow larger. At the last stage of the activation process, La was found to be decreased to about 40 Å. This implied that the edges of the graphite crystals had been activated, thus causing the internal pores to grow and coalesce into larger pores. Activated conductive Super-P with enhanced pore properties is expected to have wide applications.

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Pore properties controlling permeability prediction in carbonates

10.22564/16cisbgf2019.284 ◽

2019 ◽

Author(s):

Roseane Missagia ◽

Marco Ceia ◽

Lorena Figueiredo ◽

Irineu Neto

Keyword(s):

Permeability Prediction ◽

Pore Properties

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LRRC8A homohexameric channels poorly recapitulate VRAC regulation and pharmacology

AJP Cell Physiology ◽

10.1152/ajpcell.00454.2020 ◽

2020 ◽

Author(s):

Toshiki Yamada ◽

Eric E. Figueroa ◽

Jerod S. Denton ◽

Kevin Strange

Keyword(s):

Electron Microscopy ◽

Voltage Dependence ◽

Function Analysis ◽

Cell Swelling ◽

Independent Manner ◽

Cryo Electron Microscopy ◽

Homologous Position ◽

Pore Properties ◽

Hct116 Cells

Swelling-activated VRACs are heterohexameric channels comprising LRRC8A and at least one other LRRC8 paralog. Cryo-electron microscopy (EM) structures of non-native LRRC8A and LRRC8D homohexamers have been described. We demonstrate here that LRRC8A homohexamers poorly recapitulate VRAC functional properties. Unlike VRACs, LRRC8A channels heterologously expressed in Lrr8c-/- HCT116 cells are poorly activated by low intracellular ionic strength (µ) and insensitive to cell swelling with normal µ. Combining low µ with swelling modestly activates LRRC8A allowing characterization of pore properties. VRACs are strongly inhibited by 10 mM DCPIB in a voltage-independent manner. In contrast, DCPIB block of LRRC8A is weak and voltage sensitive. Cryo-EM structures indicate that DCPIB block is dependent on arginine 103. Consistent with this, LRRC8A R103F mutants are insensitive to DCPIB. However, a LRRC8 chimeric channel in which R103 is replaced by a leucine at the homologous position is inhibited ~90% by 10 mM DCPIB in a voltage-independent manner. Coexpression of LRRC8A and LRRC8C gives rise to channels with DCPIB sensitivity that is strongly µ-dependent. At normal intracellular µ, LRRC8A+LRRC8C heterohexamers exhibit strong, voltage-independent DCPIB block that is insensitive to R103F. DCPIB inhibition is greatly reduced and exhibits voltage dependence with low intracellular µ. The R103F mutation has no effect on maximal DCPIB inhibition but eliminates voltage-dependence under low µ conditions. Our findings demonstrate that the LRRC8A cryo-EM structure and the use of heterologously expressed LRRC8 heterohexameric channels pose significant limitations for VRAC mutagenesis-based structure-function analysis. Native VRAC function is most closely mimicked by chimeric LRRC8 homohexameric channels.

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