Solid‐state electrolytes have attracted considerable attention in new energy‐related devices due to their high safety and broad application platform. Polyoxometalates (POMs) are a kind of ...molecular‐level cluster compounds with unique structures. In recent years, owing to their abundant physicochemical properties (including high ionic conductivity and reversible redox activity), POMs have shown great potential in becoming a new generation of solid‐state electrolytes. In this review, an overview is investigated about how POMs have evolved as ion‐conducting materials from basic research to novel solid‐state electrolytes in energy devices. First, some expressive POM‐based ion‐conducting materials in recent years are introduced and classified, mainly inspecting their structural and functional relationship. After that, it is further focused on the application of these ion‐conducting electrolytes in the fields of proton exchange membranes, supercapacitors, and ion batteries. In addition, some properties of POMs (such as inherent dimension, capable of forming stable hydrogen bonds, and reversible bonding to water molecules) enable these functional POM‐based electrolytes to be employed in innovative applications such as ion selection, humidity sensing, and smart materials. Finally, some fundamental recommendations are given on the current opportunities and challenges of POM‐based ion‐conducting electrolytes.
Polyoxometalate (POM) nanoclusters with unique structures hold enormous promise in the realms of energy‐related devices, due to their reversible redox activity and high ionic conductivity. The annotations in this review are envisioned to provide an overview of how POMs have evolved as ion‐conducting materials from basic research to novel solid‐state electrolytes in energy devices.
Proton exchange membrane fuel cells are still limited as state-of-art proton exchange membranes perform poorly at high and low temperature and are easily damaged by harsh electrochemical conditions ...such as reactive peroxide species. One effective solution to this issue is to develop new types of proton conductive materials that are capable of working in a broad temperature range. A simple vacuum-assisted filtration method is employed to obtain a well-ordered new proton-conducting membrane by immobilizing nanosized bismuth oxide clusters H
Bi
O
(NO
)
·6(H
O) {H
Bi
O
} onto graphene oxide (GO) supports (named as {H
Bi
O
}/GO). {H
Bi
O
}/GO is stable in acidic media and has high proton conductivity over the temperature range from -40 to 80 °C. The proton conductivity of the {H
Bi
O
}/GO membrane is 0.564 S cm
at 80 °C in aqueous solution (in plane), and 0.1 S cm
at 80 °C and 97% RH (out of plane), respectively. Without loss of high proton conductivity, the membrane also exhibited 100-fold lower methanol permeability than a Nafion 117 membrane. Moreover, {H
Bi
O
}/GO displayed good catalytic decomposition of hydrogen peroxide and superior humidity response and recovery properties. These advantages mean that {H
Bi
O
}/GO holds great promise as a solid-state electrolyte that can potentially be applied in energy conversion devices in the future.
Objectives:
Esophageal squamous cell carcinoma is a highly prevalent cancer withpoor survival rate and prognosis. Increasing evidence suggests an important role for metabolic regulation in treating ...esophageal squamous cell carcinoma, but the underlying mechanism remains unclear. The pyruvate kinase M2 isoform is a key enzyme in the energy production process, and the upregulation of pyruvate kinase M2 isoform also plays a crucial role in gene transcription and tumorigenesis. The mammalian target of rapamycin pathway regulates an array of cellular functions, including protein synthesis, metabolism, and cell proliferation. The pyruvate kinase M2 isoform and mammalian target of rapamycin pathways both affect metabolism in cancers, and evidence also suggests that the mammalian target of rapamycin downstream transcription factor hypoxia-inducible factor-1α regulates pyruvate kinase M2 isoform. We therefore investigated the regulatory mechanism among pyruvate kinase M2 isoform, mammalian target of rapamycin, and aerobic glycolysis in esophageal squamous cell carcinoma, hoping to prove that mammalian target of rapamycin pathway regulates pyruvate kinase M2 isoform to affect glycolysis in esophageal squamous cell carcinoma.
Methods:
Immunohistochemical staining was used to compare pyruvate kinase M2 isoform and phospho-mammalian target of rapamycin expression in 30 human pathological esophageal squamous cell carcinoma sections and 30 nontumoral esophageal tissues. Short hairpin RNA was used to inhibit pyruvate kinase M2 isoform and activate mammalian target of rapamycin, after which we monitored changes in glucose consumption and lactate production. Finally, we determined the expression of pyruvate kinase M2 isoform and the mammalian target of rapamycin downstream transcription factor hypoxia-inducible factor-1α, as well as glucose consumption and lactate production, following the modification of mammalian target of rapamycin expression.
Results:
Immunohistochemical staining showed that both phospho-mammalian target of rapamycin and pyruvate kinase M2 isoform expression were higher in esophageal squamous cell carcinoma than in nontumor tissues. Glucose consumption and lactate production measurements demonstrated that altering mammalian target of rapamycin and pyruvate kinase M2 isoform levels caused corresponding changes in glycolysis in esophageal squamous cell carcinoma cells. When mammalian target of rapamycin was activated or inhibited, expression of pyruvate kinase M2 isoform and hypoxia-inducible factor-1α as well as glycolysis were altered, indicating that mammalian target of rapamycin regulates pyruvate kinase M2 isoform via the downstream transcription factor hypoxia-inducible factor-1α, thereby affecting glycolysis in esophageal squamous cell carcinoma.
Conclusion:
Mammalian target of rapamycin pathway promotes aerobic glycolysis in esophageal squamous cell carcinoma by upregulating pyruvate kinase M2 isoform. Both proteins can serve as molecular targets for novel therapeutic strategies.
High ion conductivity and low electrode-electrolyte interface resistance are intensively pursued topics for the development of solid-state Li-ion batteries with high safety and energy density. Here, ...we propose a design using keto-enamine covalent organic frameworks (TPBD) and polyethylene oxide (PEO) to prepare a solid-state electrolyte (TPBD-LiPF6@PEO), achieving a high ion conductivity of 0.543 mS cm−1 at 25°C and optimizing the electrode-electrolyte interface resistance in Li-ion batteries. Solid-state nuclear magnetic resonance experiments and density functional theory calculations show that the strong interaction between the –C=O site in TPBD and Li+ ions promotes the dissociation of LiPF6. The assembled LiFePO4|TPBD-LiPF6@PEO|Li batteries without using liquid electrolytes offer a specific capacity of nearly 140 mAh g−1 at 0.2 C with a columbic efficiency of 99.6% after 200 cycles at 25°C. This strategy for preparing solid-state electrolytes provides practical ideas and suggestions in the development of solid-state energy devices.
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•The –C=O groups in TPBD frameworks promote the dissociation of LiPF6•TPBD reduces the crystallinity of PEO and enhances mechanical strength of the electrolyte•Fast ion conduction is achieved due to the optimized interface resistance•Solid-state Li-ion batteries can operate at 25°C without adding any liquid electrolyte
The low conductivity of solid electrolytes and the interface resistance of solid-state batteries have long been scientific problems that plague the development of solid-state Li-ion batteries. Cheng et al. report a fibrous covalent organic framework TPBD that can promote the dissociation of LiPF6, combining with flexible PEO to prepare an inorganic/polymer solid electrolyte. The results show that the electrode-electrolyte interface impedance is greatly reduced, realizing the operation of solid-state battery at room temperature without the addition of liquid electrolyte.
A Class of Weak Hopf Algebras Cheng, Dongming
International Journal of Mathematics and Mathematical Sciences,
2010, Volume:
2010, Issue:
1
Journal Article
Peer reviewed
Open access
We introduce a class of noncommutative and noncocommutative weak Hopf algebras with infinite Ext quivers and study their structure. We decompose them into a direct sum of two algebras. The coalgebra ...structures of these weak Hopf algebras are described by their Ext quiver. The weak Hopf extension of Hopf algebra Hn has a quotient Hopf algebra and a sub-Hopf algebra which are isomorphic to Hn.
As a new class of crystalline porous organic materials, covalent organic frameworks (COFs) have attracted considerable attention for proton conduction owing to their regular channels and tailored ...functionality. However, most COFs are insoluble and unprocessable, which makes membrane preparation for practical use a challenge. In this study, we used surface‐initiated condensation polymerization of a trialdehyde and a phenylenediamine for the synthesis of sulfonic COF (SCOF) coatings. The COF layer thickness could be finely tuned from 10 to 100 nm by controlling the polymerization time. Moreover, free‐standing COF membranes were obtained by sacrificing the bridging layer without any decomposition of the COF structure. Benefiting from the abundant sulfonic acid groups in the COF channels, the proton conductivity of the SCOF membrane reached 0.54 S cm−1 at 80 °C in pure water. To our knowledge, this is one of the highest values for a pristine COF membrane in the absence of additional additives.
A free‐standing covalent organic framework (COF) membrane with controlled thickness was obtained by using a surface‐initiated polymerization strategy (see picture). The rigid organic skeleton and defined pore structure of the COF membrane as well as the abundance of sulfonic acid groups throughout the layer led to superior proton conductivity of 0.54 S cm−1 at 80 °C in pure water.
•A novel three-equation two-phase flow model is proposed for sedimentation and consolidation.•Fluid pressure increases with initial sediment concentration, necessitating incorporation of ...non-hydrostatic pressure.•Inertial effects become significant with larger grains, indicating the need to incorporate inertial forces.
Sedimentation and consolidation, a multi-physical phenomenon of great significance in aquatic environments, usually involves dynamic pore pressure, inertial effects, fluid-particle interphase interaction and solid stress. However, simplified models for sedimentation and consolidation typically assume hydrostatic mixture pressure and neglect inertial effects without proper justifications. Here, a one-dimensional three-equation two-phase flow model (TTP) is proposed for sedimentation and consolidation, which directly resolves dynamic fluid pressure and inertial terms. The present TTP model is benchmarked against a series of experimental cases and two existing four-equation two-phase flow (FTP) models. It features encouraging performance as compared to measured data and computed results of the existing FTP model. Furthermore, the present TTP model shows superior computing efficiency over the FTP models. To investigate the influences of inertial effects and non-hydrostatic mixture pressure, two simplified versions of the TTP model are constructed and compared with the TTP model. It is shown that incorporating inertial effects and non-hydrostatic fluid pressure are important for accurately predicting the sedimentation-consolidation process. The present study facilitates a promising framework for modelling sedimentation and consolidation, thereby supporting effective sediment management.
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