Search Results (330)

During the process of oil and gas drilling, due to the existence of pores or micro-cracks, drilling fluid is prone to invade the formation. Under the action of hydration expansion of clay in the formation and liquid pressure, wellbore instability occurs. In order to reduce the wellbore instability caused by drilling fluid intrusion into the formation, this study proposed a method of forming a dynamic hydrogen bond cross-linked network weak gel structure with modified nano-silica and P(AM-AAC). The plugging performance of the drilling fluid and the performance of inhibiting the hydration of shale were evaluated through various experimental methods. The results show that the gel composite system (GCS) effectively optimizes the plugging performance of drilling fluid. The 1% GCS can reduce the linear expansion rate of cuttings to 14.8% and increase the recovery rate of cuttings to 96.7%, and its hydration inhibition effect is better than that of KCl and polyamines. The dynamic cross-linked network structure can significantly increase the viscosity of drilling fluid. Meanwhile, by taking advantage of the liquid-phase viscosity effect and the physical blocking effect, the loss of drilling fluid can be significantly reduced. Mechanism studies conducted using zeta potential measurement, SEM analysis, contact angle measurement and capillary force assessment have shown that modified nano-silica stabilizes the wellbore by physically blocking the nano-pores of shale and changing the wettability of the shale surface from hydrophilic to hydrophobic when the contact angle exceeds 60°, thereby reducing capillary force and surface free energy. Meanwhile, the dynamic cross-linked network can reduce the seepage of free water into the formation, thereby significantly lowering the fluid loss of the drilling fluid. This research provides new insights into improving the stability of the wellbore in drilling fluids. Full article

As an efficient clean energy technology, water electrolysis for hydrogen production has its efficiency limited by the sluggish oxygen evolution reaction (OER) kinetics, which drives the demand for the development of high-performance anode OER catalysts. This work constructs bimetallic (Al, Mn) co-doped nanoporous spinel CoFe₂O₄ (np-CFO) with a tunable structure and composition as an OER catalyst through a simple two-step dealloying strategy. The as-formed np-CFO (Al and Mn) features a hierarchical flaky configuration; that is, there are a large number of fine nanosheets attached to the surface of a regular micron-sized flake, which not only increases the number of active sites but also enhances mass transport efficiency. Consequently, the optimized catalyst exhibits a low OER overpotential of only 320 mV at a current density of 10 mA cm⁻², a minimal Tafel slope of 45.09 mV dec⁻¹, and exceptional durability. Even under industrial conditions (6 M KOH, 60 °C), it only needs 1.83 V to achieve a current density of 500 mA cm⁻² and can maintain good stability for approximately 100 h at this high current density. Theoretical simulations indicate that Al and Mn co-doping could indeed optimize the electronic structure of CFO and thus decrease the energy barrier of OER to 1.35 eV. This work offers a practical approach towards synthesizing efficient and stable OER catalysts. Full article

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

The effect of periodical heatwaves and related thermal stratification in freshwater aquatic ecosystems has been a hot research issue. A large dataset of samples was generated from samples exposed to temporary thermal stratification in mesocosms mimicking shallow eutrophic freshwater lakes. Temperature regimes were based on IPCC climate warming scenarios, enabling simulation of future warming conditions. Surface oxygen levels reached 19.37 mg/L, while bottom layers dropped to 0.07 mg/L during stratification. Analysis by FlowCAM revealed dominance of Cyanobacteria under ambient conditions (up to 99.2%), while Cryptophyta (up to 98.9%) and Chlorophyta (up to 99.9%) were predominant in the A2 and A2+50% climate scenarios, respectively. We identified temperature changes and shifts in nutrient concentrations, particularly phosphate, as critical factors in microbial community composition. Furthermore, five distinct Microcystis morphospecies identified by FlowCAM-based analysis were associated with different microbial clusters. The combined use of imaging flow cytometry, which differentiates phytoplankton based on morphological parameters, and nanopore long-read sequencing analysis has shed light into the dynamics of microbial communities associated with different Microcystis morphospecies. In our observations, a peak of algicidal bacteria abundance often coincides with or is followed by a decline in the Cyanobacteria. These findings highlight the importance of species-level classification in the analysis of complex ecosystem interactions and the dynamics of algal blooms in freshwater bodies in response to anthropogenic effects and climate change. Full article

Hippophae rhamnoides subsp. sinensis is extensively found in China, where the annual precipitation ranges from 400 to 800 mm. It is the most dominant species in natural sea buckthorn forests and the primary cultivar for artificial ecological plantations. Additionally, it exhibits significant nutritional and medicinal value, making it a renowned eco-economic tree species. Despite extensive research into its ecological functions and health benefits, the mitochondrial genome of this widespread species has not yet been published, and knowledge of the mitochondrial genome is crucial for understanding plant environmental adaptation, evolution, and maternal inheritance. Therefore, the complete mitochondrial genome was successfully assembled by aligning third-generation sequencing data to the reference genome sequence using the Illumina NovaSeq 6000 platform and Nanopore Prometh ION technologies. Additionally, the gene structure, composition, repeat sequences, codon usage bias, homologous fragments, and phylogeny-related indicators were also analyzed. The results showed that the length of the mitochondrial genome is 454,489 bp, containing 30 tRNA genes, three rRNA genes, 40 PCGs, and two pseudogenes. A total of 411 C-to-U RNA editing sites were identified in 33 protein-coding genes (PCGs), with higher frequencies observed in ccmFn, ccmB, nad5, ccmC, nad2, and nad7 genes. Moreover, 31 chloroplast-derived fragments were detected, accounting for 11.86% of the mitochondrial genome length. The ccmB, nad4L, and nad7 genes related to energy metabolism exhibited positive selection pressure. The mitochondrial genome sequence similarity between H. rhamnoides subsp. sinensis and H. tibetana or H. salicifolia was 99.34% and 99.40%, respectively. Fifteen shared gene clusters were identified between H. rhamnoides subsp. sinensis and H. tibetana. Phylogenetically, the Rosales order showed close relationships with Fagales, Fabales, Malpighiales, and Celastrales. These findings provide fundamental data for exploring the widespread distribution of H. rhamnoides subsp. sinensis and offer theoretical support for understanding the evolutionary mechanisms within the Hippophae genus and the selection of molecular breeding targets. Full article

A superhydrophobic surface with hierarchical micro/nano-array structures was successfully fabricated on 6061 aluminum alloy through a combination of femtosecond laser etching and anodic oxidation. Femtosecond laser etching formed a regularly arranged microscale “pit-protrusion” array on the aluminum alloy surface. After modification with a fluorosilane ethanol solution, the surface exhibited superhydrophobicity with a contact angle of 154°. Subsequently, the anodic oxidation process formed an anodic oxide film dominated by an array of aluminum oxide (Al₂O₃) nanopores at the submicron scale. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that the nanopore structures uniformly and continuously covered the laser-ablated layer. This hierarchical structure significantly increased the surface water contact angle to 162°. Wettability analysis showed that the prepared composite coating formed an air layer accounting for 91% of the surface area. Compared with the sample only treated by femtosecond laser etching, the presence of the Al₂O₃ nanopore structure significantly enhanced the mechanical durability, superhydrophobic durability, and corrosion resistance of the superhydrophobic surface. The proposed multi-step fabrication strategy offers an innovative method for creating multifunctional, durable superhydrophobic coatings and has important implications for their large-scale industrial use. Full article

The oral cavity harbors a highly intricate and dynamic microbial ecosystem of multiple microhabitats supporting diverse microbial populations. As the second most complex microbiome in the human body, surpassed only by the gut, the oral microbiome comprises over 1000 species. Disruptions in the microbial balance have been associated with an increased risk of both oral diseases (dental caries and periodontitis) and systemic conditions, including inflammatory diseases and certain types of cancers. In our pilot study, we purified bacterial DNA from pre-treated, saponin-based, host-depleted saliva samples and performed 16S amplicon sequencing, using Oxford Nanopore Technologies, to identify bacterial composition and investigate changes in the oral microbiota of patients with solid tumors in response to chemotherapy, either alone or in combination with immunotherapy. We found significant reductions in microbial diversity of the oral microbiota following cancer treatment, which may contribute to post-therapeutic complications such as oral mucositis. Moreover, our findings indicate that on the one hand, following chemotherapy treatment the microbial profile is characterized by an increased abundance of Streptococcus, Gemella, and Granulicatella and a decrease in the abundance of Neisseria and Veillonella. On the other hand, post combined treatment, only Streptococcus relative abundance increased, Veillonella exhibited a slight decline, and Haemophilus and Neisseria displayed a marked decrease, whilst Granulicatella and Gemella remained relatively stable. Our findings underline the impact of cancer therapy on the oral microbiome, highlighting the potential for precision-based strategies to restore microbial balance and minimize treatment-related complications. Full article

Kimchi is a fermented Korean food typically made with napa cabbage, garlic, radish, ginger, and chili pepper. It is becoming increasingly popular due to its flavor, high fiber content, and purported probiotic benefits. The microbial ecology of the fermentation community has been extensively studied, though what’s less understood is how its microbial community changes when nutrients or pathogens are introduced. To study this, we used gnotobiotic cabbage media inoculated with a kimchi starter culture as a model system. These inoculated samples were exposed to E. coli or Bacillus cereus, with or without added nutrients in the form of tryptic soy broth (TSB). We tracked pH, colony-forming units (CFUs), and community composition over time. We also used Oxford Nanopore sequencing to analyze the 16S rRNA gene (V4–V9), followed by use of the Emu algorithm for taxonomic assignments. As expected, LABs suppressed pathogens, but this effect was weaker early on in the nutrient-rich condition. Pathogen exposure changed the overall community—Lactobacillus species became more common, and Leuconostoc mesenteroides less so. Interestingly, adding nutrients alone caused similar microbial shifts to those seen with pathogen exposure. This could suggest that nutrient levels have a larger impact on the final microbiome structure than direct microbial competition. Together, these findings suggest that monitoring total microbial composition, and not just the presence of pathogens, may be important for ensuring kimchi fermentation reproducibility. Full article

The mechanical properties of grouting materials and their cured grouts significantly impact the reinforcement effectiveness in deep coal mine roadways. This study employed shear rheology tests of slurry, structural tests, NMR (nuclear magnetic resonance), and uniaxial compression tests to comparatively analyze the mechanical characteristics of a composite cement-based grouting material (HGC), ordinary Portland cement (OPC), and sulfated aluminum cement (SAC) slurry and their cured grouts. The HGC (High-performance Grouting Composite) slurry is formulated with 15.75% sulfated aluminum cement (SAC), 54.25% ordinary Portland cement (OPC), 10% fly ash, and 20% mineral powder, achieving a water/cement ratio of 0.26. The results indicate that HGC slurry more closely follows power-law flow characteristics, while OPC and SAC slurries fit better with the Bingham model. The structural recovery time for HGC slurry after high-strain disturbances is 52 s, significantly lower than the 312 s for OPC and 121 s for SAC, indicating that HGC can quickly produce hydration products that re-bond the flocculated structure. NMR T2 spectra show that HGC cured grouts have the lowest porosity, predominantly featuring inter-nanopores, whereas OPC and SAC have more super-nanopores. Uniaxial compression tests show that the uniaxial compressive strength of HGC, SAC, and OPC samples at various curing ages gradually decreases. Compared to traditional cementitious materials, HGC exhibits a rapid increase in uniaxial compressive strength within the first seven days, with an increase rate of approximately 77.97%. Finally, the relationship between micropore distribution and strength is analyzed, and the micro-mechanisms underlying the strength differences of different grouting materials are discussed. This study aids in developing a comparative analysis system of mechanical properties for deep surrounding rock grouting materials, providing a reference for selecting grouting materials for various engineering fractured rock masses. Full article

Spray-drying is a flexible method for creating fine porous composites with controlled size and morphology. This study investigates how the morphology and porosity of the spray-dried powder of nano-alumina and polyvinylpyrrolidone (PVP-30) granules are affected by both the feed rate and the binder concentration. Droplet size and velocity distributions, measured with a HiWatch system, showed that higher feed rates produce larger droplets with faster velocities, therefore affecting the final morphology of the dried product. The morphology of the dried granules was analyzed using inline SOPAT imaging. While mercury intrusion porosimetry quantified the nano-pore volume and nano-pore size of the granules, offline scanning electron microscopy (SEM) was also used to characterize the morphology of the dried product. The findings show that, while raising the binder concentration produces a more compact morphology with a lower nano-pore volume, higher feed rates produce larger granules with a larger nano-pore volume. This study offers fundamental insights that can support the future development of control strategies for optimizing the production of spray-dried porous alumina–polymer nanocomposites by means of knowledge about the relationship between these process parameters and product qualities. Full article

Kazakhstan’s rich biodiversity includes diverse apple populations, notably the wild apple tree (Malus sieversii) prized for traits like disease resistance and adaptability, potentially aiding breeding programs. Analyzing their microbiomes offers insights into bacterial diversity and how it influences apple tree development, making it a reliable method for understanding ecological interactions. In this research, 334 apple tree samples were collected from different mountain ranges in southeastern Kazakhstan. An analysis using nanopore-based 16S rRNA sequencing showed a distinct similarity in the microbiome compositions of samples from the Zhongar and Ile Alatau mountain ranges, with a predominance of Pseudomonadaceae, Enterobacteriaceae, and Microbacteriaceae. In contrast, samples from Ketmen ridge showed a higher prevalence of Enterobacteriaceae. Alongside the less represented Pseudomonadaceae family, in the Ketmen ridge region, bacteria of the Xanthomonadaceae, Alcaligenaceae, and Brucellaceae families were also present. Across all regions, beneficial plant-associated bacteria were identified, such as Pseudomonas veronii, Stenotrophomonas geniculata, and Kocuria rhizophila, potentially enhancing plant resilience. However, opportunistic phytopathogens were also detected, including Pseudomonas viridiflava and Serratia marcescens, particularly in the Ile Alatau region. These findings highlight the complex microbial interactions in M. sieversii, thus offering key insights into host—microbe relationships that can inform apple breeding and ecological preservation efforts. Full article

Nanoporous material liquid systems (NMLSs) demonstrate promising potential for blast protection due to their high energy absorption density. This investigation numerically evaluated the use of NMLSs in mitigating blast effects on fiber–composite circular structures. The coupled Eulerian–Lagrangian method was employed to establish the numerical models of fiber alone, water–fiber, and NMLS–fiber, subjected to the internal close-field blast loading. The simulations focused on a widely studied NMLS, nanoporous silica particles immersed in distilled water. Four NMLSs, featuring varying particle-to-water ratios yet identical densities to that of water, were designed to modulate the energy absorption capacity while maintaining identical mass. These NMLSs were modeled by Equation of State (EOS) compaction. The dynamic responses of the fiber circles in the simulations were compared to evaluate the blast mitigation of different liquids. When the explosive mass was relatively small or medium, both the water and NMLSs exhibited blast mitigation. The NMLSs outperformed water because the energy absorption capacity caused a greater attenuation of blast pressure in the NMLSs. In the small-mass explosive cases, all four NMLSs could rapidly reduce the blast pressure to the infiltration pressure but their wave impedances decreased as the particle-to-water ratio increased, resulting in that a NMLS with greater energy absorption capacity, however, had inferior blast mitigation performance. When the explosive mass was relatively large, all the fiber circles experienced significant fiber failure and only the NMLS with the greatest energy absorption capacity exhibited blast mitigation. Full article

Cave environments represent extreme and underexplored ecosystems wherein fungi play a crucial role in nutrient cycling and ecological dynamics. This study provides the first comprehensive assessment of fungal diversity in air samples from caves across Portugal, with six samples from five locations being assessed through culture-dependent and metabarcoding approaches. From the five bat roosts studied, eleven morphologically distinct fungal colonies were isolated, with genera such as Aspergillus, Penicillium, and Chaetomium identified. Concurrently, Oxford Nanopore sequencing of the internal transcribed spacer (ITS) region of fungal rDNA revealed 286 genera, with Aspergillus, Candida, and Calyptella dominating across the sites. Diversity indices and community composition analyses, including Principal Coordinate Analysis (PCoA) and hierarchical clustering, highlighted distinct fungal profiles influenced by site-specific environmental factors and human activity. The data underscores the dual role of fungi in bat roosts as essential decomposers, emphasizing their adaptability to oligotrophic conditions. These findings advance our understanding of subterranean fungal ecology and emphasize the need for targeted conservation efforts to protect cave ecosystems from anthropogenic impacts. Full article

Based on a review of the existing literature on the use of diatomite and the functioning of phase-change heat accumulators, in this study, we conducted empirical research on the creation of a phase-change composite based on Carpathian diatomite. As part of our mineralogical research, we determined the phase composition of the Carpathian diatomites in this work. Their internal nanostructure was identified. Nanopores create regular systems that, depending on the variety of diatoms, may have sieve, tubular, or “honeycomb” shapes. Diatomites’ internal structure benefits the absorption capacity of phase-change materials (PCM). The obtained calorimetric thermograms of the organic phase-change material and the diatomite compound highlighted an extension of the temperature range in which phase transformation occurs from 4–5 °C (for pure PCM RT28HC) to 15–17 °C for the composites tested with weight proportions of 1:1 and 4:6. In the case of water-rich varieties, the presence of mixed-package minerals, i.e., montmorillonite, with its small size and specific 2:1 package structure, can hinder the penetration and accumulation of PCM. The ability to bind and accumulate heat will be influenced by the size of the diatomite particles or the relative size of the PCM and pores, i.e., structural and textural features. Full article

Both hepatitis B virus (HBV), an hepadnavirus with a DNA genome, and hepatitis A virus (HAV), a picornavirus, require the TRAMP-like host ZCCHC14-TENT4 complex for efficient replication. However, whereas HBV requires the nucleotidyltransferase activity of TENT4 to extend and stabilize the 3′ poly(A) tails of mRNA transcribed from its genome, the role played by TENT4 in HAV replication is uncertain. HAV proteins are synthesized directly from its genomic RNA, which possesses a 3′ poly(A) tail, with its length and composition presumably maintained by 3D^pol-catalyzed RNA transcription during its replicative cycle. Using nanopore long-read sequencing of RNA from infected cells, we confirm here that the length of the HAV 3′ poly(A) tail is not altered by treating infected cells with RG7834, a small molecule TENT4 inhibitor with potent anti-HAV activity. Despite this, TENT4 catalytic activity is essential for HAV replication. Surprisingly, nanopore sequencing revealed a low abundance of HAV subgenomic RNAs (hsRNAs) that extend from the 5′ end of the genome to a site within the 5′ untranslated RNA (5′UTR) immediately downstream of a stem-loop to which the ZCCHC14-TENT4 complex is recruited. These hsRNAs are polyadenylated, and their abundance is sharply reduced by RG7834 treatment, implying they are likely products of TENT4. Similar subgenomic RNAs were not identified in poliovirus-infected cells. hsRNAs are present not only in HAV-infected cell culture but also in the liver of HAV-infected mice, where they represent 1–3% of all HAV transcripts, suggesting their physiological relevance. However, transfecting exogenous hsRNA into TENT4-depleted cells failed to rescue HAV replication, leaving the functional role of hsRNA unresolved. These findings reveal a novel picornaviral subgenomic RNA species while highlighting mechanistic differences in the manner in which HAV and HBV exploit the host ZCCHC4-TENT4 complex for their replication. Full article