Search Results (4,643)

The methods for determining total organic carbon (TOC) in carbonate rocks are mainly the conventional TOC method and the montmorillonite thickening method. However, both methods suffer from organic matter loss during the measurement process and inaccuracy in determining low TOC concentrations (TOC ≤ 0.5%). In this study, carbonate rock samples from the Ordovician of the Ordos Basin and synthetic standard samples were investigated using the conventional TOC method, the montmorillonite thickening method, and a newly developed elemental analysis method based on sodium polyacrylate thickening after acid digestion. The results show that gypsum-facies carbonate rocks contain organic acid salts, whereas shoal-facies and argillaceous carbonate rocks do not develop organic acid salts. For synthetic samples spiked with small-molecule organic acid salts, the relative error of the conventional TOC method exceeds 98%; for large-molecule organic acid salts, the relative error is relatively small, below 16%. The TOC measurement error of the sodium polyacrylate thickening method is lower than that of the montmorillonite thickening method. Compared with the conventional and montmorillonite methods, when carbonate rock TOC ≤ 0.5%, the sodium polyacrylate thickening method yields TOC errors mostly ≤10%, with better stability and lower error rates. The new TOC method for carbonate rocks exhibits higher accuracy and stability in determining organic carbon content, and can more objectively reflect the total organic carbon (TOC) of samples. Full article

The mechanical characteristics and the rupture behavior of dry paper and papers immersed in pure water or a carboxymethyl cellulose (CMC) aqueous solution were investigated by measuring the shape changes due to the immersion and by uniaxial tensile tests. The weight changes and dimensional changes for these samples due to the immersion were evaluated by the gravimetric method and image analysis, respectively. The absorption ratio of the paper was 2.3 for pure water, and it increased up to 2.7 with the CMC concentration. A deformation of 5% at maximum was observed in the direction perpendicular to the fiber orientation due to the absorption. All the samples demonstrated similar stress–strain curves in the regions of linear viscoelasticity and plastic deformation. The peak stress, Young’s modulus, and strain energy density of CMC wet paper showed lower values than those of water wet paper, while the peak strain was the same for both samples. Similar behavior was found in the cross direction, although the difference was not significant. These results strongly indicate that the penetration and adsorption of CMC molecules lead to a large expansion, resulting in the disentanglement of paper fibers and a significant reduction in the mechanical properties due to the strong fluid lubrication effect. Full article

Structural analysis using X-rays and electron beams has long provided the average arrangement of atoms and molecules—that is, “structural information”—with high precision. By contrast, static measurements cannot directly yield dynamic information on how a material changes over time; instead, information on motion is convolved into a single numerical value such as the B-factor (atomic displacement parameter). Taking this limitation as its starting point, this review surveys the recent trend of introducing a time axis into measurements to observe material dynamics directly. First, we outline the technological foundations that have made the transition from static to time-resolved measurement possible. It rests on the dramatic shortening of exposure times, enabled by the increased brilliance of X-ray and electron sources and by advances in detection technology such as direct photon-counting detectors. Next, we survey dynamic measurement techniques, including time-resolved X-ray crystallography, coherent X-ray scattering, neutron scattering, and time-resolved electron microscopy. We also point out the essential limitation that most of them still return ensemble or volume averages. Building on this, we systematically describe diffracted X-ray tracking (DXT), diffracted X-ray blinking (DXB), small-angle X-ray blinking (SAXB), transmitted X-ray blinking (TXB), and electron-beam molecular dynamics (EBMD), which use gold nanocrystals and gold nanoparticles as motion probes. We distinguish throughout between methods that follow individual objects—DXT and EBMD, which yield trajectories of single labeled molecules or single particles—and methods that analyze intensity fluctuations arising from many contributors within one pixel or illuminated volume—DXB, SAXB and TXB. The latter are not single-molecule measurements; rather, they replace a global ensemble average by a spatially localized statistical one, retaining local heterogeneity that a bulk measurement would average away. Finally, we discuss the implementation and prospects of the large-volume data analysis—principal component analysis, Bayesian inference, machine learning, and autonomous measurement—needed to handle the explosively increasing amount of information that the time axis introduces. We close with the outlook that time-resolved measurement incorporating AI and big-data analysis will become established as a new measurement platform that complements and extends conventional static structural analysis. Full article

Bioactive peptides are an important source of therapeutic molecules and molecular scaffolds involved in defense, signaling, and immune regulation. Despite the extraordinary diversity of Coleoptera, the structural landscape of beetle-derived bioactive peptides remains largely unexplored, limiting our understanding of their evolutionary diversity and biotechnological potential. Here, we performed a large-scale structural survey of predicted toxin-like peptide scaffolds across publicly available Coleoptera transcriptomes by integrating transcriptome mining, peptide maturation prediction, physicochemical characterization, AlphaFold 3 structural modeling, structural similarity analyses, and interpretable machine learning. We identified 291 candidate peptides, of which 155 contained canonical signal peptides and 273 produced mature peptides within the expected size range of known bioactive peptides. Structural analyses revealed that, despite extensive sequence diversity, many candidates were organized into a comparatively restricted repertoire of compact cysteine-rich architectures, indicating that structural similarity is retained across peptides exhibiting substantial primary-sequence variation. Comparative structural analyses further identified recurrent protein architectures shared across multiple beetle lineages, while machine learning prioritization integrated structural and biochemical descriptors to identify high-confidence candidates for future functional characterization. These analyses establish the first structural atlas of predicted toxin-like peptides across Coleoptera and demonstrate that structure-guided transcriptome mining provides a powerful framework for uncovering recurrent bioactive peptide scaffolds that would remain largely undetected using sequence-based approaches alone. Beyond expanding our understanding of peptide evolution in beetles, this resource is a foundation for future structural, functional, and biotechnological exploration of bioactive peptides in underexplored animal groups. Full article

Per- and polyfluoroalkyl substances (PFASs) are persistent, surface-active contaminants for which soil represents the largest terrestrial reservoir. This review synthesizes a rapidly expanding but fragmented body of literature in order to reframe PFAS not merely as a groundwater transport problem but as a systemic stressor of soil health, drawing together their reported effects on the chemical, physical and biological properties of soils and giving particular attention to the calcareous, alkaline, carbon-poor and seasonally dry soils of the Mediterranean. The reviewed evidence suggests that, chemically, PFASs perturb the coupled carbon and nitrogen cycles rather than the bulk soil reaction, transiently stimulating and then depressing organic carbon turnover, drawing down the dissolved organic carbon pool and disturbing nitrification, while their retention and bioavailability are governed chiefly by organic carbon, chain length and pH. Physically, the surfactant character that defines these molecules lowers the surface tension of soil water and concentrates PFASs at the air–water interface, so that in unsaturated and drought-prone soils much of the burden is retained and then released episodically, most clearly on rewetting after dry periods. Biologically, the literature consistently reports dose-dependent declines in microbial viability, diversity and enzyme activity, alongside toxicity to earthworms and other soil fauna, with sensitivity strongly modulated by soil texture and organic matter. Across all three domains, the Mediterranean emerges as both potentially vulnerable and conspicuously understudied, the available data being clustered in a few western countries and effectively absent for much of the eastern and southern basin, so that the regional assessment offered here rests largely on mechanistic inference rather than on direct observation. The review argues that these coupled mechanistic and geographic gaps define an urgent, region-specific research agenda for the protection of soil health. Full article

We studied the electronic origin of the NMR nuclear magnetic shieldings ($\sigma$) of compounds containing the following transition metal atoms: $M=$ Zn, Cd, Hg, Co, Rh, Cr, Mo, W. The electronic mechanisms that underlie the relativistic effects on those shieldings were assessed with the LRESC–Loc model, which permits one to quantify the set of leading relativistic electronic mechanisms responsible for such effects in terms of well-known non-relativistic operators, and also allows for the determination of which molecular orbitals (MOs) are involved in each of those mechanisms. These MOs are such that the chemist’s intuition associated with core, lone-pair (LP), and bonding MOs is satisfied. The LRESC model is a reliable semi-relativistic methodology that has been shown to reproduce, in a semiquantitative manner, the magnetic shieldings and experimental chemical shifts of transition metals in a large set of molecules. Several new features appear in the shieldings analyzed. Trends in the total shieldings within a given family of compounds depend on relativistic effects—the spin-orbit mechanism is one of the most involved—though, within it, one must consider the Fermi contact (FC) and the spin-dipolar (SD) mechanisms. We found that the contributions that are due to partially filled d atomic orbitals (AOs) become too large when the electron correlation is not properly included. This is overcome in our case using density functional theory. A large influence of lone-pairs of $\pi$-type on $\sigma$(M) is also seen in some of the molecules studied. Full article

Pseudomonas aeruginosa (PA) is a clinically relevant opportunistic pathogen whose persistence and antimicrobial tolerance are largely driven by biofilm formation and quorum-sensing (QS)-regulated virulence. Targeting QS has therefore emerged as an antivirulence strategy that attenuates pathogenicity without exerting strong selective pressure on bacterial growth. This systematic review (2020–2024) analyzes recent advances in the identification of QS inhibitors against PA, emphasizing studies that integrate in silico approaches. Forty-six studies met the inclusion criteria. All employed molecular docking, and 36.9% (n = 17) incorporated molecular dynamics simulations. While valuable for initial detection, these computational predictions have inherent limitations in accurately estimating binding energy and conformational dynamics, requiring empirical validation to confirm actual biological activity. Approximately one-fifth of the studies were exclusively computational, whereas the remainder combined in silico screening with in vitro and, in some cases, in vivo assays. The most frequently investigated QS regulators were LasR, PqsR, and RhlR, alongside additional virulence-associated proteins. The evaluated compounds encompassed phytochemicals, synthetic molecules, nanomaterials and natural product-derived compounds, several of which demonstrated experimental evidence of biofilm attenuation and reduction in QS-regulated virulence factors. Overall, the findings highlight the value of integrating computational and experimental strategies to rationally prioritize antivirulence candidates. However, the intrinsic complexity and redundancy of the QS network suggest that future research should increasingly focus on multitarget approaches and on the exploration of chemically diverse and previously underexplored compound libraries to improve efficacy against PA biofilms. Full article

Postbiotic preparations contain inanimate microbial cells and a diverse mixture of cell-wall structures, proteins, polysaccharides, lipids, metabolites, and vesicle-associated materials. Although many of these components have been proposed as key bioactives, most are identified through compositional profiling, enrichment in active fractions, or testing of purified molecules. Such findings demonstrate biological activity but do not necessarily show that a candidate contributes to the effect of the original preparation. This review examines the experimental approaches used to narrow candidate lists and evaluate functional contribution, including phenotype-guided comparison, activity-guided fractionation, selective depletion, multi-omics profiling, structural characterization, dose–response testing, mechanistic intervention, and reconstitution. A structured narrative search of Web of Science Core Collection, PubMed, and Scopus through 30 March 2026, supplemented by citation tracking, identified the relevant literature; 15 representative primary studies that examined defined candidates and provided evidence beyond compositional detection were selected and appraised across seven preparation-level attribution domains. An appraisal of representative studies shows that current evidence largely supports the activity of individual candidates, whereas preparation-level attribution remains uncommon. Stronger evidence requires quantification of the candidate in the source material, selective removal with appropriate controls, and restoration at a preparation-relevant dose. Structural heterogeneity, processing history, molecular state, dose, and experimental context must also be considered. This evidence-based approach can support bioactive-component validation, batch consistency, and the design of future preclinical and human studies. Full article

At present, there is no cure for the human genetic disorder ataxia-telangiectasia (A-T), which is managed by supportive care. This disorder arises due to mutations in the ATM (ataxia-telangiectasia mutated) gene and is characterised by a defect in the response to DNA damage, oxidative stress, mitochondrial dysfunction and immune deficiency. The ATM protein is activated by DNA damage, reactive oxygen species (ROS), and a variety of other stimuli, which leads to the phosphorylation or altered cellular localisation of multiple protein substrates that participate in cellular defence pathways. ATM plays a central role in orchestrating cellular defence against stress, which forms a focal point for approaches to treating the symptoms in this disorder. These strategies involve boosting mitochondrial function and dampening the inflammatory response. A more direct approach to treatment is gene therapy, yet the leading method using Adeno-Associated Virus (AAV) is hampered by the large size of the ATM gene itself. The use of antisense oligonucleotides (ASO) as an alternative gene therapeutic approach to treat patients has been increasingly utilised. However, only certain mutations fit the criteria for ASO-based intervention, which encourages rescue through readthrough of premature truncation mutations. For this reason, small-molecule-based therapies addressing the multi-system nature of the disease are urgently required. We address these different approaches to therapy and the outcome of numerous recent clinical trials with A-T patients, as well as ongoing research that has potential to lead to therapy. Full article

Underground storage of green hydrogen is a strategic enabler of large-scale renewable deployment, but its feasibility rests on a hard problem: keeping a small, highly mobile molecule confined underground for decades without safety or environmental risk. This critical review examines the containment mechanisms of hydrogen across underground storage types, focusing on geological barriers, well integrity and sealing materials. We evaluate the containment capabilities of salt cavities, deep aquifers and depleted reservoirs, with particular attention to the viscoplastic, self-healing properties of salt that promote confinement, and to the vulnerabilities of well infrastructure and salt–cement interfaces. Emerging alternatives, including lined rock caverns and repurposed abandoned mines, are assessed alongside their distinct operating configurations and use cases. Leakage mechanisms including diffusion, advection, microcracking, cement degradation and hydrogen–material interactions are analysed alongside geomechanical modelling, microbial activity, monitoring strategies, regulatory frameworks, and techno-economic and environmental considerations, including the integration of carbon capture, utilisation and storage (CCUS) with underground hydrogen storage. Well integrity emerges as the dominant risk factor across storage types. The review concludes with design criteria, monitoring priorities and research needs to guide the safe, sustainable deployment of underground hydrogen storage, providing a scientific foundation for future numerical and experimental work on storage tightness. Full article

Metal–Organic Frameworks (MOFs) have undergone remarkable development in recent decades, transforming them into one of the most dynamic classes of emerging composite materials. These crystalline, porous coordination networks, built from metal ions or metal clusters interconnected by organic linkers, form architectures with tunable porosity, large specific surface area, and chemical functionality. Due to their remarkable stability and customizable functionalities, MOFs have attracted significant attention in recent years as promising materials for different applications. In 2025, Susumu Kitagawa, Omar Yaghi, and Richard Robson were awarded the Nobel Prize in Chemistry for pioneering the development of MOF crystalline materials with spacious internal cavities that can store, filter or catalyze molecules. This review systematically consolidates the recent literature (since 2020) on MOF-based systems, covering state-of-the-art performance, synthesis advantages and limitations, and the influence of reaction parameters on morphology, structure, and luminescent properties. The rapid yearly increase in MOF-related publications, continuing strongly into 2026, reflects the growing global interest and highlights the rising importance of their design and applications. This trend motivates the central focus of this paper, which, in a single work, emphasizes the integrated use of MOFs in luminescent sensing, biosensing, the removal of heavy metals, microplastics, and organic dyes in water treatment, and hydrogen storage. Finally, the challenges, conclusions and future perspectives of MOF-based materials will be highlighted with the aim of providing guidelines for their further development and additional applications. Full article

Climate change is placing global agriculture under growing pressure, as plants must withstand extreme environmental conditions such as drought and high salinity, both inducing osmotic and oxidative stress. As part of their survival strategies, plants accumulate protective molecules (osmolytes), including the amino acid proline. For decades, plant biology has largely assumed that high proline accumulation under stress signals strong stress tolerance. However, this review challenges that “proline-centric” perspective. Analyses across a wide range of plant species reveal a more complex picture. Stress-induced proline accumulation is not universal: in some species, proline levels remain relatively unchanged, with other metabolites acting as functional osmolytes, or increase only in response to artificially applied severe stress conditions. Even when proline increases, its absolute concentrations may be too low to contribute significantly to osmotic adjustment. Nevertheless, proline may still be involved in stress tolerance mechanisms through its additional roles, detoxifying reactive oxygen species (ROS), directly stabilising proteins or acting as a stress signalling molecule. Comparative analyses of genetically related taxa with varying degrees of stress tolerance sometimes show negative correlations between proline accumulation and tolerance, with higher proline concentrations measured in the most sensitive genotypes. Overall, the evidence indicates that proline‘s role in plant survival is highly context-dependent and strongly influenced by genetic background and must therefore be evaluated on a case-by-case basis. Distinguishing whether proline acts as an adaptive defence or merely as a biochemical marker of physiological strain under stress is essential for accurately assessing plant stress tolerance. Full article

Despite decades of surface science research, there is a lack of an universal approach to define the adsorption geometry in catalysis on metal nanoparticles and surfaces. The unified framework introduced in this work allows the comparison of binding sites across different facets and particle-size metals, including stepped surfaces, adatoms and surface vacancies. In this study, we identify 18 adsorption sites on metal nanoparticles and surfaces that have either a face-centred cubic (FCC) or hexagonal close-packed (HCP) structure. Most metals in the periodic table have these structures and we determined the adsorption site geometry on a nanoparticle using a geometric approach with physical magnetic ball-and-stick models. These geometric models include the existence of an octahedral or tetrahedral hole beneath the adsorption site, as these can affect the adsorption site strengths of adsorbates. Furthermore, these adsorption sites are a combination of three-fold hollows and four-fold hollows, which are adsorption sites known to activate diatomic molecules (e.g., N₂ and CO). In addition, adsorption of large-molecular-weight adsorbates can be defined on these sites as they provide multiple contact points in contrast to the typical four-fold hollow, three-fold hollow, and bridge and atop adsorption sites used in heterogeneous catalysis. We find that there are nine geometrically distinct adsorption site topologies composed of square (i.e., 100) and triangular (i.e., 111) motifs. These adsorption site topologies, when combined with a characteristic zeta angle (ζ), result in 18 distinct adsorption site geometries that can be found on metal nanoparticles and surfaces. A systematic naming system for these adsorption sites is provided that defines the adsorption site geometry explicitly. Using this approach, we find that there are five different types of B5 sites, an adsorption site that has been previously found to activate dinitrogen on ruthenium for the ammonia synthesis reaction. Full article

Power transformers are core equipment in power grids, and polar substances in their insulating oil—such as furfural, methanol, water, and formic acid—serve as key biomarkers for assessing insulation condition. Traditional detection methods are time-consuming and operationally complex, making it difficult to meet the demand for rapid on-site testing. Terahertz spectroscopy, with its high sensitivity to polar molecules and non-destructive testing capabilities, shows great potential for assessing insulation oil aging. However, existing research has largely focused on the detection of single substances or overall condition assessment, and faces challenges such as limited spectral sample data and insufficient model generalization ability. In this study, a transmission-type terahertz time-domain spectroscopy detection platform was established, and insulating oil samples containing different volume concentrations of polar substances were prepared to obtain their absorption spectra. To address the challenge of training with a small sample size, we proposed a multi-strategy spectral data augmentation method that integrates Gaussian noise addition, baseline shifting and intensity scaling, and minor frequency-axis shifts, thereby expanding the trainable data volume to four times that of the original data. Based on this, we used principal component analysis to extract spectral features and established a support vector machine classification model for pattern recognition of the four polar substances mentioned above. The results show that the model without data augmentation achieved only 86.0% accuracy on the test set, indicating poor generalization ability; however, after applying data augmentation, the model’s recognition accuracy on the test set improved to 96.0%, with both recall and precision for each substance remaining above 90.0%, effectively overcoming the issue of overfitting. This study demonstrates that terahertz spectroscopy, combined with data augmentation and machine learning algorithms, enables rapid, high-precision, and non-destructive identification of polar substances in insulating oil, thereby offering a potential new technical pathway for transformer insulation condition assessment. Full article

Cancer prevention through dietary intervention utilizing bioactive natural compounds has garnered significant attention due to the therapeutic limitations of conventional cancer treatments. These plant-derived active compounds, including polyphenols, terpenoids, organosulfur compounds, bioactive peptides, and alkaloids, possess potent anticancer properties. This systemic review addresses a critical gap in the scientific literature by elucidating the precise multitargeted oncogenic regulatory mechanisms of these molecules. A comprehensive methodology was employed, involving a systematic literature search across major electronic databases (including PubMed, Web of Science, Embase, and SCOPUS) to identify relevant original peer-reviewed studies. The evidence gathered demonstrates that these active compounds deliver significant health benefits and protect cells by modulating crucial molecular targets involved in cell cycle regulation, apoptosis, oncogenic signaling, epigenetic control, angiogenesis, oxidative stress, and inflammation. Specifically, they operate via multi-targeted cascades, such as inhibiting the PI3K/Akt, NF-κB, and STAT3 pathways. To provide a clear structural overview, these active compounds are categorized comprehensively based on their botanical and structural origins, including spices, fruits, and rhizomes. However, despite their promising bioactivities, these compounds have not yet been fully translated into clinical therapy due to challenges such as low bioavailability, rapid metabolism, limited systematic exposure, and a lack of convincing evidence from large-scale clinical trials. Although most current evidence remains rooted in in vitro and experimental animal models, clinical validation through high-quality trials is still required. Ultimately, this review underscores the potential of these active compounds and highlights how advances in formulation and nano delivery strategies offer promising solutions for effective cancer prevention. Full article