Search Results (94)

Synthetic nanopores were recently demonstrated with memristive and nonlinear voltage-current behaviors, akin to ion channels in a cell membrane. Such ionic devices are considered a promising candidate for the development of brain-inspired neuromorphic computing techniques. In this work, we show the composite behavior of nanopore-array large memristors, formed with different membrane materials, pore sizes, electrolytes, and device arrangements. Anodic aluminum oxide (AAO) membranes with 5 nm and 20 nm diameter pores and track-etched polycarbonate (PCTE) membranes with 10 nm diameter pores are tested and shown to demonstrate memristive and nonlinear behaviors with approximately 10⁷–10¹⁰ pores in parallel when electrolyte concentration across the membranes is asymmetric. Ion diffusion through the large number of channels induces time-dependent electrolyte asymmetry that drives the system through different memristive states. The behaviors of series composite memristors with different configurations are also presented. In addition to helping understand fluidic devices and circuits for neuromorphic computing, the results also shed light on the development of field-assisted ion-selection-membrane filtration techniques as well as the investigations of large neurons and giant synapses. Further work is needed to de-embed parasitic components of the measurement setup to obtain intrinsic large memristor properties. Full article

This study focuses on addressing the issues of water flooding and mass transfer limitations in proton exchange membrane fuel cells (PEMFCs) under high current density conditions. A multi-scale gradient pore gas diffusion layer (GDL) is designed to enhance fuel cell performance. The pore structure is precisely controlled using a self-assembled mold, resulting in the fabrication of a GDL with a gradient distribution of pore diameters ranging from 80 to 170 μm. Experimental results indicate that, with the optimized gradient pore GDL, the peak power density of the fuel cell reaches 1.18 W·cm−², representing a 20% improvement compared to the traditional structure. A mechanism analysis reveals that this structure establishes a concentrated water transport pathway through channels while enabling gas diffusion and transport driven by concentration gradients, thereby achieving the collaborative optimization of gas–liquid transport. This approach offers a novel solution for managing water in PEMFCs operating under high current density conditions, and holds significant implications for advancing the commercialization of PEMFC technology. Full article

The microscale solid and pore structures of waste is crucial for the bio-hydro-mechanical behaviors of landfilled municipal solid waste (MSW). The quantitative analysis of the structural characteristics of MSW is still limited. In this study, borehole MSW samples at different depths (i.e., 0 m, 2.5 m, 5 m, 7.5 m, 10 m, and 12.5 m) were drilled from a landfill. The waste composition and basic physical properties of these samples were tested in laboratory. Solid and pore structural characteristics were studied through computed tomography (CT) analysis. The results indicate that the ratio of cellulose content to lignin content (i.e., C/L) decreased from 0.85 to 0.47 with increasing depth. For solid particles, two-dimensional (2D) particles constituted the greatest fraction (60.22~72.16%), which showed a decrease with increasing depth. The deeper sample tended to have more fine particles. For pores, the void ratio decreased from 1.68 to 1.10 with increasing depth, with more small pore channels. Meanwhile, the average pore diameter coefficient (λ) decreased from 0.209 to 0.190, the pore angle (θ_e) decreased from 29.6° to 17.8°, the tortuosity (τ) increased from 1.129 to 1.184, and the connectivity (c_e) decreased from 12.0 to 4.1. These quantitative findings can further the understanding of fluid flow behaviors in landfilled waste. Full article

The amyloid-beta 1-42 (Aβ1-42) oligomers are the most cytotoxic species of the amyloid family and play a key role in the pathology of Alzheimer’s Disease (AD). They have been shown to damage cellular membranes, but the exact mechanism is complex and not well understood. Multiple routes of membrane damage have been proposed, including the formation of pores and ion channels. In this work, we study the membrane damage induced by Aβ1-42 oligomers using black lipid membrane (BLM) electrophysiology and compare their action with gramicidin, known to form ion channels. Our data show that Aβ1-42 oligomers can induce a variety of damage in the lipid membranes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and cholesterol (CHOL), including small ion channels, similar to the gramicidin channels, with an average inner diameter smaller than 5 Å. These channels have a short retaining time in lipid membranes, suggesting that they are highly dynamic. Our studies provide new insights into the mechanism of membrane damage caused by Aβ1-42 oligomers and extend the current perception of the Aβ channelopathy hypothesis. It provides a more in-depth understanding of the molecular mechanism by which small Aβ oligomers induce cytotoxicity by interacting with lipid membranes in AD. Full article

In this study, a method for creating networked macropores through tillage using Eisenia fetida attracted by food sources derived from decomposing straw was proposed. The effects of Eisenia fetida activity and corn stalk addition, as well as the synergistic effects of Bacillus subtilis, on macropore formation were systematically studied. A 3D visualization technique was used to render the pore network model. When compared with undisturbed soil, the results demonstrate that cultivation using earthworms attracted by food sources from decomposing straw creates a soil pore structure with the most significant effect. The 3D porosity of the soil increased 6.90-fold, its average pore volume increased 5.49-fold, and its equivalent diameter increased 4.88-fold. Cylindrical pores, which accounted for the largest proportion (4.38%), had a channel radius of 1–5 mm and comprised approximately 86.7% of all macropores. The channel length increased by 28.5%, the average roundness decreased by 2.5%, and the average coordination number increased by 33.3%. The macroporous network structure formed by these earthworm-generated pores was more beneficial for improving the structure of phaeozem, offering technical support for the field application of earthworm farming. Full article

The seepage diffusion of cement grouting materials into a sandy medium is influenced by the skeleton’s adsorption and the pore channels’ tortuosity, resulting in heterogeneous retention of cement particles during migration. This study established a theoretical model for the filtration coefficient based on the mass balance equation and linear filtration law. Grouting tests were conducted to determine the density of the cement slurry at various diffusion positions, and the filtration coefficient was calculated using the theoretical model. Results indicate that the filtration coefficient varies dynamically along the diffusion distance rather than remaining constant. The surface filtration range of Grade 42.5 Portland Cement slurry in sample S1 is approximately 30 cm, with a final diffusion distance of 190 cm. In contrast, the surface filtration ranges for the 800 mesh superfine cement in S2 and the 1250 mesh superfine cement in S3 are less than 10 cm, resulting in final diffusion distances of 69 cm and 87 cm, respectively. This demonstrates that a longer surface filtration range in the sand sample corresponds to a farther final diffusion distance of the slurry. Additionally, a larger ratio of sand pore diameter to cement particle size results in a smaller filtration coefficient and a greater slurry diffusion distance. Under a constant water–cement ratio, smaller cement particle sizes are associated with decreased slurry fluidity, which reduces the diffusion of cement slurry within the sandy medium. The research findings provide valuable insights for designing borehole spacing in grouting treatment for sandy media. Full article

In this study, a conceptual turbine blade model with internal cooling channels was designed and fabricated using the selective laser melting (SLM) process. The optimal manufacturing orientation was evaluated through simulations, and the results indicated that vertical orientation yielded the best outcomes, minimizing support material usage and distortion despite increased manufacturing time. Two configurations were produced, namely, an entire-turbine blade model and a cross-sectional model. Non-destructive analyses, including 3D laser scanning for dimensional accuracy, surface roughness measurements, and liquid penetrant testing, were conducted. Visual inspection revealed manufacturing limitations, particularly in the cooling channels at the leading and trailing edges. The trailing edge was too thin to accommodate the 0.5 mm channel diameter, and the channels in the leading edge were undersized and potentially clogged with unmelted powder. The dimensional deviations were within the acceptable limits for the SLM-fabricated metal parts. The surface roughness measurements were aligned with the literature values for metal additive manufacturing. Liquid penetrant testing confirmed the absence of cracks, pores, and lack-of-fusion defects. The SLM is a viable manufacturing process for turbine blades with internal cooling channels; however, significant attention should be paid to the design of additive manufacturing conditions to obtain the best results after manufacturing. Full article

The full potential of glauconite-based nanocomposites as micronutrient fertilizers remains underexplored, particularly their interaction with Zn, Cu, and B. Despite the promising applications, the mechanisms of nutrient sorption and their effects on plant growth require further investigation, especially concerning structural changes and nutrient delivery efficiency. This study investigates the modification of glauconite with Zn, Cu, and B solutions to create multifunctional nanocomposites with enhanced properties. It was established that the activation process preserves the primary globular–lamellar morphology of glauconite while introducing structural changes. Nanocomposites were synthesized using chemical activation and characterized using XRD, SEM-EDS, TEM, FTIR, and BET analyses. Agrochemical tests evaluated their effects on oat growth under controlled conditions. Nanocomposites with zinc sulfate exhibited an increase in specific surface area and mesoporosity, enhancing sorption capacity and facilitating the formation of inner-sphere complexes on the mineral’s basal surface. Modification with copper led to the formation of secondary phases, such as sulfates, on the surfaces of microflakes and globules while preserving the crystalline structure with inner-sphere coordination of Cu²⁺. Boron-modified nanocomposites were characterized by localized restructuring, pore channeling, and an increase in mesopore diameter, along with the formation of outer-sphere complexes relative to the basal surface of glauconite. Thermogravimetric and calorimetric analyses with mass spectrometry revealed specific endothermic and exothermic effects, particularly in Zn-modified samples, confirming changes in dehydration energetics. Agricultural tests on oats (Avena sativa) demonstrated the effectiveness of Cu- and B-modified nanocomposites in improving plant growth parameters, including a 7% increase in plant height and a 6.4% increase in dry weight. Zn-modified nanocomposites showed high germination rates (up to 100%) at low dosages but require optimization to avoid phytotoxicity at higher concentrations. The findings highlight the potential of adapting nanocomposites for targeted nutrient release. Additionally, glauconite nanocomposites have potential applications in restoring degraded soils, treating polluted runoff, and developing slow-release agrochemical systems. Full article

In this paper, well Keshen 221 was taken as the research object. The stagnant water–rock static experiment showed that, after 8 weeks of the residual water–rock static reaction, the pore size of the inner profile of the rock slice increased from 5 μm to 90 μm, and calcium carbonate crystals were deposited in the hole. Combined with the microscopic visualization model, it is observed that the reservoir blockage mostly occurs at the pore throat diameter, and the small fracture (30 μm) is blocked first, then the large fracture (50 μm). So, it is inferred that the blockage of the reservoir flow channel is caused by the migration of the crystals precipitated by the interaction between the stagnant water and the reservoir rock. On this basis, the TOUGHREACT reservoir model was further constructed to simulate the scaling of the stagnant water in the reservoir matrix and used to compare the scaling of the fractures with 7% and 30% porosity and the retained water at 0.658 m and 768 m. The pre-results of reservoir scaling show that the scaling is more serious when the fractures occur in the far well zone than when the fractures occur in the well entry zone. At the same location, the deposition of large fractures is six times that of small fractures, and the scaling is more severe in large fractures. Full article

Within the phylum Cnidaria, sea anemones (class Anthozoa) express a rich diversity of ion-channel peptide modulators with biomedical applications, but corollary discoveries from jellyfish (subphylum Medusozoa) are lacking. To bridge this gap, bioactivities of previously unexplored proteinaceous and small molecular weight (~15 kDa to 5 kDa) venom components were assessed in a mouse dorsal root ganglia (DRG) high-content calcium-imaging assay, known as constellation pharmacology. While the addition of crude venom led to nonspecific cell death and Fura-2 signal leakage due to pore-forming activity, purified small molecular weight fractions of venom demonstrated three main, concentration-dependent and reversible effects on defined heterogeneous cell types found in the primary cultures of mouse DRG. These three phenotypic responses are herein referred to as phenotype A, B and C: excitatory amplification (A) or inhibition (B) of KCl-induced calcium signals, and test compound-induced disturbances to baseline calcium levels (C). Most notably, certain Alatina alata venom fractions showed phenotype A effects in all DRG neurons; Physalia physalis and Chironex fleckeri fractions predominantly showed phenotype B effects in small- and medium-diameter neurons. Finally, specific Physalia physalis and Alatina alata venom components induced direct excitatory responses (phenotype C) in glial cells. These findings demonstrate a diversity of neuroactive compounds in jellyfish venom potentially targeting a constellation of ion channels and ligand-gated receptors with broad physiological implications. Full article

The chemical gating of gap junction channels is mediated by cytosolic calcium (Ca²⁺_i) at concentrations ([Ca²⁺]_i) ranging from high nanomolar (nM) to low micromolar (µM) range. Since the proteins of gap junctions, connexins/innexins, lack high-affinity Ca²⁺-binding sites, most likely gating is mediated by a Ca²⁺-binding protein, calmodulin (CaM) being the best candidate. Indeed, the role of Ca²⁺-CaM in gating is well supported by studies that have tested CaM blockers, CaM expression inhibition, testing of CaM mutants, co-localization of CaM and connexins, existence of CaM-binding sites in connexins/innexins, and expression of connexins (Cx) mutants, among others. Based on these data, since 2000, we have published a Ca²⁺-CaM-cork gating model. Despite convincing evidence for the Ca²⁺-CaM role in gating, a recent study has proposed an alternative gating model that would involve a direct electrostatic Ca²⁺-connexin interaction. However, this study, which tested the effect of unphysiologically high [Ca²⁺]_i on the structure of isolated junctions, reported that neither changes in the channel’s pore diameter nor connexin conformational changes are present, in spite of exposure of isolated gap junctions to [Ca²⁺]_i as high at the 20 mM. In conclusion, data generated in the past four decades by multiple experimental approaches have clearly demonstrated the direct role of Ca²⁺-CaM in gap junction channel gating. Full article

The confinement effect in micro- and nanopores gives rise to distinct flow characteristics in fluids. Clarifying the fluid migration pattern in confined space is crucial for understanding and explaining the abnormal flow phenomena in unconventional reservoirs. In this study, flow characteristics of water and oil in alumina nanochannels were investigated with diameters ranging from 21 nm to 120 nm, and a heterogeneous viscosity flow model considering boundary fluid was proposed. Compared with the prediction of the HP equation, both types of fluids exhibit significant flow suppression in nanochannels. As the channel size decreases, the deviation degree increases. The fluid viscosity of the boundary region displays an upward trend as the channel size decreases and the influence of the interaction between the liquid and solid walls intensifies. The thickness of the boundary region gradually decreases with increasing pressure and eventually reaches a stable value, which is primarily determined by the strength of the interaction between the liquid and solid surfaces. Both the pore size and wettability are essential factors that affect the fluid flow. When the space scale is extremely small, the impact of wettability becomes more pronounced. Finally, the application of the heterogeneous flow model for permeability evaluation has yielded favorable fitting results. The model is of great significance for studying the fluid flow behavior in unconventional reservoirs. Full article

Titanium silicon molecular zeolite (TS-1) plays an important role in catalytic reactions due to its unique nanostructure. The straight channel on TS-1 was parallel to the orientation of the short b-axis and directly exposed to the aperture of the 10-member ring with a diameter of 0.54 nm × 0.56 nm. This structure could effectively reduce the diffuse restriction of bulk organic compounds during the oxidative desulfurization process. As a kind of cationic polymer electrolyte, polydimethyldiallyl ammonium chloride (PDDA) contains continuous [C₈H₁₆N⁺Cl⁻] chain segments, in which the Cl⁻ could function as an effective structure-directing agent in the synthesis of nanomaterials. The chain of PDDA could adequately interact with the [0 1 0] plane in the preparation process of zeolite, and then the TS-1 nanosheet with short b-axis thickness (6 nm) could be obtained. The pore structure of the TS-1 nanosheet is controlled by regulating the content of PDDA. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N₂ physical adsorption analysis, infrared absorption spectrum and ultraviolet–visible spectrum were used to determine the TS-1. The thinner nanosheets exhibit excellent catalytic performance in oxidative desulfurization of dibenzothiophene (DBT), in which the removal rate could remain at 100% after three recycles. Here, the TS-1 nanosheet with short b-axis thickness has a promising future in catalytic reactions. Full article

α-Latrotoxin (α-LTX) was found to form two-dimensional (2D) monolayer arrays in solution at relatively low concentrations (0.1 mg/mL), with the toxin tetramer constituting a unit cell. The crystals were imaged using cryogenic electron microscopy (cryoEM), and image analysis yielded a ~12 Å projection map. At this resolution, no major conformational changes between the crystalline and solution states of α-LTX tetramers were observed. Electrophysiological studies showed that, under the conditions of crystallization, α-LTX simultaneously formed multiple channels in biological membranes that displayed coordinated gating. Two types of channels with conductance levels of 120 and 208 pS were identified. Furthermore, we observed two distinct tetramer conformations of tetramers both when observed as monodisperse single particles and within the 2D crystals, with pore diameters of 11 and 13.5 Å, suggestive of a flickering pore in the middle of the tetramer, which may correspond to the two states of toxin channels with different conductance levels. We discuss the structural changes that occur in α-LTX tetramers in solution and propose a mechanism of α-LTX insertion into the membrane. The propensity of α-LTX tetramers to form 2D crystals may explain many features of α-LTX toxicology and suggest that other pore-forming toxins may also form arrays of channels to exert maximal toxic effect. Full article

In this study, three randomly packed beds with varying tube-to-particle diameter ratios (D/d) are constructed using the discrete element method (DEM) and simulated via CFD under low pore Reynolds numbers (Re_p < 100). An innovation of this research lies in the application of hydrogen in randomly packed beds, coupled with the consideration of its temperature-dependent thermal properties. The axial analysis of the heat transfer characteristics shows that PB−5 and PB−6 achieve thermal equilibrium 44% and 58% faster than PB−4, respectively, demonstrating enhanced heat transfer efficiency. However, at higher flow rates (0.8 m/s), the large-sized fluid channels in PB−6 severely impact the heat transfer efficiency, slightly reducing it compared to PB−5. Additionally, this study introduces a localized segmentation method for calculating the axial local Nusselt number, showing that the axial local Nusselt number (Nu) not only exhibits an inverse relationship with the axial porosity distribution, but also matches its amplitude fluctuations. The wall effect significantly impacts the flow and temperature distribution in the packed bed, causing notable velocity and temperature oscillations in the near-wall region. In the near-wall region, the average temperature is lower than in the core region, and the axial temperature profile exhibits more intense oscillations. These findings may provide insights into the use of hydrogen in randomly packed beds, which are vital for enhancing industrial applications such as hydrogen storage and utilization. Full article