Search Results (366)

Understanding the microscopic occurrence states of shale oil—particularly the distribution between adsorbed and free phases—is essential for optimizing the development of unconventional reservoirs. In this study, we propose an integrated methodology that combines experimental techniques with molecular dynamics simulations to investigate shale oil behavior within kerogen nanopores. Specifically, pyrolysis–gas chromatography–mass spectrometry (PY-GC-MS), solid-state ¹³C nuclear magnetic resonance (¹³C NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were performed to construct a representative kerogen molecular model based on shale samples from the Lianggaoshan Formation in the Sichuan Basin. Grand Canonical Monte Carlo (GCMC) simulations and a theoretical occurrence model were applied to quantify the adsorption characteristics of n-dodecane under varying pore sizes, temperatures, and pressure. The results show that temperature exerts a stronger influence than pore diameter on adsorption capacity, with adsorption decreasing by over 50% at higher temperatures, and pressure has a limited effect on the adsorption amount of dodecane molecules. This study offers a robust workflow for evaluating shale oil occurrence states in complex pore systems and provides guidance for thermal stimulation strategies in tight oil reservoirs. Full article

This study is based on an experiment and a molecular dynamics simulation to investigate the distribution states and property variation laws of crude oil in nanopores, aiming to provide theoretical support for efficient unconventional oil and gas development. Focus is placed on the distribution mechanisms of multicomponent crude oil in oil-wet siltstone (SiO₂) and dolomitic rock (dolomite, CaMg₃(CO₃)₄) nanopores, with comprehensive consideration of key factors including pore size, rock type, and CO₂ flooding on crude oil distribution at 353 K and 40 MPa. It is revealed that aromatic hydrocarbons (toluene) in multicomponent crude oil are preferentially adsorbed on pore walls due to π-π interactions, while n-hexane diffuses toward the pore center driven by hydrophobic effects. Pore size significantly affects the distribution states of crude oil: ordered adsorption structures form for n-hexane in 2 nm pores, whereas distributions become dispersed in 9 nm pores, with adsorption energy changing as pore size increases. Dolomite exhibits a significantly higher adsorption energy than SiO₂ due to surface roughness and calcium–magnesium ion crystal fields. CO₂ weakens the interaction between crude oil and pore walls through competitive adsorption and reduces viscosity via dissolution, promoting crude oil mobility. Nuclear magnetic resonance (NMR) experiments further verified the effect of CO₂ on crude oil stripping in pores. This study not only clarifies the collaborative adsorption mechanisms and displacement regulation laws of multi-component crude oil in nanopores but also provides a solid theoretical basis for CO₂ injection strategies in unconventional reservoir development. Full article

Thermoelectric (TE) materials represent a critical frontier in sustainable energy conversion technologies, providing direct thermal-to-electrical energy conversion with solid-state reliability. The optimizations of TE performance demand a nuanced comprehension of structure–property relationships across diverse length scales. This review summarizes established and emerging spectroscopic and microscopic techniques used to characterize inorganic and polymer TE materials, specifically poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). For inorganic TE, ultraviolet–visible (UV–Vis) spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) are widely applied for electronic structure characterization. For phase analysis of inorganic TE materials, Raman spectroscopy (RS), electron energy loss spectroscopy (EELS), and nuclear magnetic resonance (NMR) spectroscopy are utilized. For analyzing the surface morphology and crystalline structure, chemical scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) are commonly used. For polymer TE materials, ultraviolet−visible–near-infrared (UV−Vis−NIR) spectroscopy and ultraviolet photoelectron spectroscopy (UPS) are generally employed for determining electronic structure. For functional group analysis of polymer TE, attenuated total reflectance–Fourier-transform infrared (ATR−FTIR) spectroscopy and RS are broadly utilized. XPS is used for elemental composition analysis of polymer TE. For the surface morphology of polymer TE, atomic force microscopic (AFM) and SEM are applied. Grazing incidence wide-angle X-ray scattering (GIWAXS) and XRD are employed for analyzing the crystalline structures of polymer TE materials. These techniques elucidate electronic, structural, morphological, and chemical properties, aiding in optimizing TE properties like conductivity, thermal stability, and mechanical strength. This review also suggests future research directions, including in situ methods and machine learning-assisted multi-dimensional spectroscopy to enhance TE performance for applications in electronic devices, energy storage, and solar cells. Full article

Alkaptonuria (AKU) is a rare metabolic disorder caused by homogentisate 1,2-dioxygenase (HGD) deficiency, leading to homogentisic acid (HGA) accumulation and ochronotic pigment deposition, which drug therapy cannot reverse. The process of pigment formation and deposition is still unclear. This study offers molecular insights into the polymeric structure, with the goal of developing future adjuvant strategies that can inhibit or reverse pigment formation, thereby complementing drug therapy in AKU. HGA polymerisation was examined under physiological, acidic, and alkaline conditions using liquid and solid phase nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), and polyacrylamide gel electrophoresis. At physiological pH, HGA polymerised slowly, while alkaline catalysis accelerated pigment formation while retaining the HGA aromatic scaffold. During the process, EPR detected a semiquinone radical intermediate, consistent with an oxidative coupling mechanism. Reactivity profiling showed the diphenol ring was essential for polymerisation, while –CH₂COOH modifications did not impair reactivity. Pigments displayed a polydisperse molecular weight range (11–50 kDa) and a strong negative charge. Solid-state NMR has revealed the presence of phenolic ether and biphenyl linkages. Collectively, these identified structural motifs can serve as a foundation for future molecular targeting related to pigment formation. Full article

Plastic pollution from polyethylene-based materials is a critical environmental concern due to their high persistence. Here, we report the first proof-of-concept application of a multitechnique analytical framework for quantifying linear low-density polyethylene (LLDPE) in Tenebrio molitor frass. Artificially enriched frass–LLDPE mixtures were analyzed using thermogravimetric analysis (TGA), TGA coupled with Fourier-Transform Infrared Spectroscopy (FTIR) and Mass Spectrometry (MS), TGA under inert atmosphere, and solid-state ¹³C nuclear magnetic resonance spectroscopy with Cross-Polarization and Magic Angle Spinning (CP-MAS NMR) ¹³C CP-MAS NMR combined with interval Partial Least Squares (iPLS) modeling. Thermal methods provided insight into decomposition pathways but showed reduced specificity at <1% w/w due to matrix interference. CP-MAS NMR offered matrix-independent quantification, with characteristic signals in the 10–45 ppm region and a calculated LOD and LOQ of 0.173% and 0.525% w/w, respectively. The LOQ lies within the reported ingestion range for T. molitor (0.8–3.2% w/w in frass), confirming biological relevance. This validated workflow establishes CP-MAS NMR as the most robust tool for quantifying polyethylene residues in complex matrices and provides a foundation for in vivo biodegradation studies and environmental monitoring. Full article

This review discusses the development of small-diameter silk-based vascular grafts, based on insights obtained through solid-state NMR structural analysis. With the increasing prevalence of cardiovascular diseases, the demand for vascular grafts with diameters of less than 6 mm is growing. Although synthetic grafts currently used in clinical settings—such as polyethylene terephthalate and expanded polytetrafluoroethylene—are effective, they tend to cause thrombosis and intimal hyperplasia when used as small-diameter vascular grafts. In response to this issue, research has been advancing on new materials that maintain excellent mechanical properties while improving biocompatibility. This review first describes how the detailed structure of silk fibroin (SF) before and after fiber formation was revealed for the first time through solid-state NMR analysis using stable isotope-labeled samples. Then it outlines design criteria for small-diameter SF-based vascular grafts, focusing on fabrication methods like electrospinning. Special attention is given to knitted SF grafts with SF sponge coatings, analyzed via ¹³C solid-state NMR in the dry and hydrated states of the sponges. In vivo performance in rat and canine models is discussed, along with chemically modified SF grafts such as silk-biodegradable polyurethane sponges and their structural and implantation results. Full article

Gastroesophageal reflux disease (GERD) is associated with symptoms such as heartburn, resulting from gastric content reflux. Alginate-based raft-forming gel formulations represent a non-pharmacological strategy for GERD management by forming a floating gel barrier in the stomach. This study evaluated three commercial anti-reflux oral gel systems under simulated fed-state gastric conditions, using in vitro magnetic resonance relaxometry techniques. Magnetic resonance imaging (MRI) was performed in 0.01 M hydrochloric acid (HCl) to visualize gel raft formation, spatial structure, and spatial distribution of effective T₂ relaxation time. Nuclear magnetic resonance (NMR) relaxometry in 0.01 M deuterium chloride (DCl) measured T₁ and T₂ relaxation times of the protons that were initially included in the preparation to assess its molecular mobility within the gel matrix. Two formulations formed floating, coherent gels, whereas the remaining one exhibited only polymer swelling without flotation. In one case, relaxometry data revealed a solid-like component that can be detected, indicating enhanced mechanical stability. The performance of each formulation was influenced by interactions among alginate, bicarbonates, and calcium ions, which determined gel consistency and flotation behavior. MRI and NMR relaxometry in vitro provide valuable non-invasive insights into the structural and functional behavior of alginate-based gel formulations. This approach supports the rational design of advanced gel-based therapies for GERD by linking molecular composition with in situ performance. Full article

Mechanochemistry has become a fundamental method in various sciences including biology and chemistry. Despite its popularity, the mechanisms behind mechanochemically induced reactions are not very well understood. In previous work, we investigated molecular-recognition processes of molecules capable of forming racemic phases in ball mill devices. Solid-state nuclear magnetic resonance (solid-state NMR) was used as the key technique to analyze such events. We now extended this study and focused on mechanochemically induced racemic-phase formations of two representative amino acids, alanine and serine, in a resonant acoustic mixer. The data reveal the importance of adding small amounts of solvents (here water) to facilitate the underlying solid-state molecular-recognition processes. The role of water therein is further studied by deuterium magic-angle spinning (MAS) NMR experiments, also revealing that resonant acoustic mixing (RAM) enables efficient hydrogen to deuterium exchange in enantiopure serine, paving the way to deuterate organic compounds in the RAM device. Full article

Proteins that span cellular membranes represent around 30% of the proteome and over 50% of drug targets. A variety of synthetic and naturally-occurring small organic molecules interact with membrane proteins and up- and down-regulate protein function. The atomic details of these regulatory molecules offer important information about protein function and aid the discovery, refinement and optimization of new drugs. X-ray crystallography and cryo-electron microscopy (cryo-EM) are not always able to resolve the structures of small molecules in their physiological sites on membrane proteins, particularly if the molecules are unstable or are reactive enzyme substrates. Solid-state nuclear magnetic resonance (SSNMR) is a valuable technique for filling in missing details on the conformations, dynamics and binding environments of small molecules regulators of membrane proteins. SSNMR does not require diffracting crystals possessing long-range order and can be performed on proteins within their native membranes and with freeze-trapping to maintain sample stability. Here, work over the last two decades is described, in which SSNMR methods have been developed to report on interactions of the ATP substrate with the Na,K-ATPase (NKA), an ion-transporting enzyme that maintains cellular potential in all animals. It is shown how a combination of SSNMR measurements on membranous NKA preparations in the frozen and fluid states have provided unique information about the molecular conformation and local environment of ATP in the high-affinity nucleotide site. A combination of chemical shift analysis using density functional theory (DFT) calculations, dipolar coupling measurements using REDOR and measurements of the rates of proton spin diffusion is appraised collectively. The work described herein highlights the methods developed and challenges encountered, which have led to a detailed and unrivalled picture of ATP in its high-affinity binding site. Full article

Geopolymers represent an innovative and environmentally sustainable alternative to traditional construction materials, offering significant potential for reducing anthropogenic CO₂ emissions. Among these, phosphoric acid-activated metakaolin-based systems have attracted increasing attention for their chemical and thermal resilience. In this study, we present a comprehensive structural and mechanical evaluation of metakaolin-based geopolymers synthesized across a wide range of Al/P molar ratios (0.8–4.0). Six formulations were systematically prepared and analyzed using X-ray powder diffraction (XRPD), small-angle X-ray scattering (SAXS), Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (ssNMR), and complementary mechanical testing. The novelty of this work lies in the integrated mapping of composition–structure–property relationships across the broad Al/P spectrum under controlled synthesis, combined with the rare application of SAXS to reveal composition-dependent nanoscale domains (~18–50 nm). We identify a stoichiometric window at Al/P ≈ 1.5, where complete acid consumption leads to a structurally homogeneous AlVI–O–P network, yielding the highest compressive strength. In contrast, acid-rich systems exhibit divergent flexural and compressive behaviors, with enhanced flexural strength linked to hydrated silica domains arising from metakaolin dealumination, quantitatively tracked by ²⁹Si MAS NMR. XRPD further reveals the formation of uncommon Si–P crystalline phases (SiP₂O₇, Si₅P₆O₂₅) under low-temperature curing in acid-rich compositions. Together, these findings provide new insights into the nanoscale structuring, phase evolution, and stoichiometric control of silica–alumino–phosphate geopolymers, highlighting strategies for optimizing their performance in demanding thermal and chemical environments. Full article

Two nitrogen-modified mesoporous MCM-41-type silicas were synthesized by the sol–gel route and post-grafting surface modification procedure, obtaining an aminopropyl-modified MCM-41 (denoted MCM-41-N) and an aminoethyl-aminopropyl-modified MCM-41 (denoted MCM-41-NN). Hexavalent chromium removal from acidified water by adsorption and reduction to Cr(III) on the solid mesophases was analyzed. The modified silicas were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectra (FT-IR), nitrogen adsorption–desorption measurements at −196 °C, X-ray photoelectron spectroscopy (XPS), ²⁹Si solid state Nuclear Magnetic Resonance (²⁹Si-RMN), and thermogravimetric analysis (TGA). Both samples exhibited very high capacities for decreasing Cr(VI) concentrations in water, according to the Langmuir isotherm model: 129.9 mg·g⁻¹ for MCM-41-N and 133.3 mg·g⁻¹ for MCM-41-NN. The chromium speciation in the supernatant after 24 h indicates that MCM-41-N had a higher capacity to reduce Cr(VI) to the less toxic Cr(III) species than MCM-41-NN: 92.9% vs. 72.5% when the initial Cr(VI) concentration was 10 mg·g⁻¹. These differences were related to the different capacity of nitrogen atoms in MCM-41-N and MCM-41-NN to interact with the surrounding surface silanols which are required for the chemical reduction in the hexavalent species to take place, as evidenced by FT-IR and XPS analysis. Also, the Cr(III)/Cr(VI) atomic ratios on the solid’s surfaces were higher for MCM-41-N. These results highlight the characteristics that nitrogen atoms incorporated into silica matrices must possess in order to maximize the transformation of Cr(VI) into the trivalent species, thereby reducing the generation of toxic waste harmful to living organisms. Full article

Solid-state lithium batteries (SSLBs) have emerged as a promising alternative to conventional lithium-ion systems due to their superior safety profile, higher energy density, and potential compatibility with lithium metal anodes. However, a major challenge hindering their widespread deployment is the formation and growth of lithium dendrites, which compromise both performance and safety. This review provides a comprehensive and structured overview of recent advances in dendrite suppression strategies, with special emphasis on the role played by the nature of the solid electrolyte. In particular, we examine suppression mechanisms and material innovations within the three main classes of solid electrolytes: sulfide-based, oxide-based, and polymer-based systems. Each electrolyte class presents distinct advantages and challenges in relation to dendrite behavior. Sulfide electrolytes, known for their high ionic conductivity and good interfacial wettability, suffer from poor mechanical strength and chemical instability. Oxide electrolytes exhibit excellent electrochemical stability and mechanical rigidity but often face high interfacial resistance. Polymer electrolytes, while mechanically flexible and easy to process, generally have lower ionic conductivity and limited thermal stability. This review discusses how these intrinsic properties influence dendrite nucleation and propagation, including the role of interfacial stress, grain boundaries, void formation, and electrochemical heterogeneity. To mitigate dendrite formation, we explore a variety of strategies including interfacial engineering (e.g., the use of artificial interlayers, surface coatings, and chemical additives), mechanical reinforcement (e.g., incorporation of nanostructured or gradient architectures, pressure modulation, and self-healing materials), and modifications of the solid electrolyte and electrode structure. Additionally, we highlight the critical role of advanced characterization techniques—such as in situ electron microscopy, synchrotron-based X-ray diffraction, vibrational spectroscopy, and nuclear magnetic resonance (NMR)—for elucidating dendrite formation mechanisms and evaluating the effectiveness of suppression strategies in real time. By integrating recent experimental and theoretical insights across multiple disciplines, this review identifies key limitations in current approaches and outlines emerging research directions. These include the design of multifunctional interphases, hybrid electrolytes, and real-time diagnostic tools aimed at enabling the development of reliable, scalable, and dendrite-free SSLBs suitable for practical applications in next-generation energy storage. Full article

A nanoparticle formulation was generated from distiller dried grains with solubles (DDGS), and its effect on the production of anthraquinones (AQs) was evaluated on Rubia tinctorum hairy roots. The DDGS material was washed with water and ethyl acetate to remove mainly the soluble organic/inorganic molecules and reduce the fat content, respectively, followed by an alkaline treatment to remove the polysaccharides. The resulting alkaline solutions were then lyophilized and redispersed in deionized water to generate a monodispersed nanoparticulate formulation (DDGS-NP) with a hydrodynamic diameter and zeta potential of 227 ± 42 nm and −53 ± 7 mV, respectively. The formulation demonstrated good colloidal stability over time, and sterilized DDGS-NPs maintained comparable physicochemical properties. The nanoparticles were enriched in protein fractions, unsaturated fatty acids, and orthophosphate anion components from DDGS, as determined by solid-state Nuclear Magnetic Resonance (NMR), X-ray photoelectron spectroscopy (XPS), organic elemental analysis (OEA), and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The DDGS-NPs were tested at different concentrations on Rubia tinctorum hairy roots, in comparison to or in combination with methyl jasmonate (MeJ), for their capacity to induce the production of AQs. All DDGS-NP concentrations increased the production of specific AQs to 7.7 (100 mg L⁻¹), 7.8 (200 mg L⁻¹), and 9.3 µmol/gFW (500 mg L⁻¹), with an extracellular AQ accumulation of 18 µM for the highest DDGS-NP concentration, in comparison with the control hairy roots (~2 µM AQ). The plant growth was not affected at any of the tested nanoparticle concentrations. Interestingly, the combination of DDGS-NPs and MeJ resulted in the highest extracellular AQ accumulation in R. tinctorum root cultures. Full article

A quantitative characterization of the change in coal molecular structures with different cyclical microwave modification parameters and a better understanding of the reaction mechanism of the modification are of great significance for the commercial extraction of coal bed methane (CBM). Therefore, long-flame coal samples obtained from the Ordos Basin, China, were modified by microwave radiation with different times, and the long-flame coal molecular structure parameters were determined by solid-state ¹³C nuclear magnetic resonance (ss¹³C NMR), Fourier transform infrared (FTIR) spectrometry, and X-ray photoelectron spectrometry (XPS). Atomistic representations of the raw long-flame coal molecular model and modified long-flame coal molecular models were established. The temperature rise, pore volume increase, mineral removal, and functional group changes after the modification have a negative effect on methane adsorption. After the modification, the decrease in surface area of the micropores reduced the adsorption site of methane in coal. As a result, the methane adsorption amount decreased linearly with the decreasing surface area. The CH₄ adsorption isotherms of the long-flame models were dynamically simulated and analyzed. The results of this study can prove that after multiple cycles of microwave modifications, the functional groups in long-flame coal were fractured, and the number of micropores was reduced, which effectively decreased the methane adsorption performance in long-flame coal seams, thereby promoting methane extraction. Microwave modification is a promising method for enhancing CBM recovery. Full article

Solid-state ¹³C NMR spectroscopy using cross-polarization magic-angle spinning is a highly valuable technique for the semi-quantitative analysis of complex solid matrices. One of its key advantages is that it does not require any manipulation of the matrix, such as extractions or other treatments, which is particularly important for preserving the integrity of unstable secondary metabolites. Glucosinolates (β-thioglucoside-N-hydrosulphates) are crucial secondary metabolites specific to Brassica species, and many of them are known to be highly unstable. In this study, we evaluated solid-state nuclear magnetic resonance spectroscopy as an alternative method for the identification and quantification of total glucosinolates in the seeds of Sisymbrium officinale, Brassica napus, Sinapis alba, Brassica nigra, and Moringa oleifera. The results obtained with this method showed good agreement with those from conventional chemical analyses of the seed material. Although, based on a limited number of samples, this preliminary study suggests that the proposed approach could be a useful alternative for quantifying total glucosinolate content in seeds. Full article