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The use of biomass feedstocks for producing high-value-added chemicals is gaining significant attention in the academic community. In this study, near-infrared carbon dots (NIR-CDs) with antimicrobial and bioimaging functions were prepared from Epigynum auritum branches and leaves using a novel green synthesis approach. The spectral properties of the synthesized NIR-CDs were characterized by ultraviolet–visible (UV-Vis) absorption and fluorescence spectroscopy. The crystal structures of the NIR-CDs were further characterized by high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). The NIR-CDs exhibited minimal toxicity, excellent biocompatibility, and high penetrability in both in vivo and in vitro environments, making them ideal luminescent probes for bioimaging applications. Moreover, the antimicrobial activity of NIR-CDs was tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), showing significant bacterial growth inhibition. The antimicrobial effect is likely attributed to the NIR-CDs disrupting the cell membrane integrity, leading to the leakage of the intracellular contents. Therefore, NIR-CDs hold promise as fluorescent bioimaging probes and antimicrobial agents. [ABSTRACT FROM AUTHOR]

Non-ionic surfactants are an important solvent in the field of green chemistry with tremendous application potential. Understanding their phase properties in bulk or in confined environments is of high commercial value. In recent years, the combination of molecular dynamics (MD) simulations with multinuclear solid-state NMR spectroscopy and calorimetric techniques has evolved into the most powerful tool for their investigation. Showing recent examples from our groups, the present review demonstrates the power and versatility of this approach, which can handle both small model-surfactants like octanol and large technical surfactants like technical polyethylene glycol (PEG) mixtures and reveals otherwise unobtainable knowledge about their phase behavior and the underlying molecular arrangements. [ABSTRACT FROM AUTHOR]

Transitions seen in the electric properties of water-absorbable poly(2,5-benzimidazole) (ABPBI) films were confirmed by electric conductivity, dielectric constant, and time-domain nuclear magnetic resonance (NMR) measurements. The electric resistance of the films was measured at room temperature using a high-resistance meter, and the dielectric constant at room temperature was measured using an LCR meter in the frequency range of 90 Hz to 8 MHz. The water absorption ratio at equilibrium absorption for the films was 37%, which corresponded to a volume fraction of water of 0.33. The electric conductivity of the films without water absorption was ~1014 S·cm−1, and it increased to ~1010 S·cm−1 with increasing volume fraction, showing a percolation threshold at a volume fraction of 0.025, and remarkable transitions at volume fractions of 0.075 and 0.135. The dielectric constant of the films without water absorption was 3.4, and it increased to 8.1 with increasing volume fraction, showing a transition only at a volume fraction of 0.135. Above a volume fraction of 0.075, where a transition in conductivity was observed, there were two relaxation times at 18–31 μs and 20–93 μs, as determined from the time-domain NMR, and these relaxation times increased with increasing volume fraction. The longer relaxation time increased significantly at a volume fraction of 0.072, which was close to the volume fraction of the transition seen in conductivity. The relationship between the chain mobility of ABPBI and the deterioration in electric insulating properties is discussed. [ABSTRACT FROM AUTHOR]

A comprehensive framework for designing a micro-nuclear magnetic resonance (NMR) front-end is presented. Key radio frequency (RF) engineering principles are established to enable efficient excitation and detection of NMR signals. This foundation aims to guide the optimal design of novel handheld NMR devices operating with magnetic fields ( B 0 ) below 0.5 Tesla and RF frequencies under 30 MHz. To address the complexities of signal-to-noise ratio optimization in this regime, a specialized metric called the coil performance factor (CPF) is introduced, emphasizing the role of coil design. Through systematic optimization under realistic constraints, an optimal coil configuration maximizing the CPF is identified. This design, with three turns, a coil width of 0.22 mm, and a coil spacing of 0.15 mm, achieves an optimal balance between magnetic field strength, homogeneity, and noise. This work serves as a valuable resource for engineers developing optimized coil designs and RF solutions for handheld NMR devices, providing clear explanations of essential concepts and a practical design methodology. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) and high-pressure mercury injection (HPMI) have been widely used as common characterization methods of pore-throat. It is generally believed that there is a power function relationship between transverse relaxation time (T2) and pore-throat radius (r), but the segmentation process of the pore-throat interval is subjective, which affects the conversion accuracy. In this paper, ordered clustering is used to improve the existing segmentation method of the pore-throat interval, eliminate the subjectivity in the segmentation process, and obtain a more accurate distribution curve of the pore-throat. For the three kinds of cores with ordinary-low permeability (K > 1 mD), ultra-low permeability (0.1 mD < K < 1 mD), and super-low permeability (K < 0.1 mD), the pore-throat distribution curves of the cores were obtained by using the improved T2 conversion method. Then, the oil and gas two-phase displacement experiment was carried out to investigate the degree of recovery and cumulative gas–oil ratio changes during the displacement process. Finally, the converted T2 spectrum was used to quantify the utilization of different pore sizes. The improved T2 conversion method not only has better accuracy but also is not limited by the pore-throat distribution types (such as unimodal, bimodal, and multi-modal, etc.) and is suitable for any core with measured HPMI pore-throat distribution and an NMR T2 spectrum. Combined with the results of core displacement and the degree of pore-throat utilization, it is found that the potential of miscible flooding to improve the recovery degree is in the order of ordinary-low permeability core (18–22%), ultra-low permeability core (25–29%), and super-low permeability core (8–12%). The utilization degree of immiscible flooding to the <10 nm pore-throat is low (up to 35%), while miscible flooding can effectively use the <3.7 nm pore-throat (up to 73%). The development effect of supercritical CO2 flooding on K < 0.1 mD reservoirs is not good, the seepage resistance of CO2 is large, the miscible flooding makes it difficult to improve the recovery degree, and the utilization effect of pore-throat is poor. [ABSTRACT FROM AUTHOR]

In deep brine oil and gas injection–production operations, the combined long-term effects of brine and carbon dioxide on rock mechanical properties are not clear. In order to solve this problem, the influence of long-term salt–CO2 environment on the mechanical properties of sandstone is discussed. The mechanism of interaction evolution and fracture propagation was studied in detail by NMR, the triaxial compression test and a CT scan. The results show that the triaxial compressive strength and mass of sandstone decrease first and then increase with the prolonging of soaking time. The proportion of micropores first decreased and then increased, while the proportion of medium and large pores first increased and then decreased. The pores obtained by Avizo's segmentation of the threshold value of CT sections first increased and then decreased, and the fractal dimensions obtained first increased and then decreased. In particular, the calcium ions in the immersion solution increased first and then decreased. The reaction rate was obtained and verified according to the changes in calcium carbonate mass and calcium ion mineralization at different times. The failure mode of the sample gradually changed from /-shaped failure to V-shaped composite failure, then to local /-shaped failure, and finally to X-shaped composite failure. On this basis, the process of sandstone was divided into the dissolution stage, precipitation stage and secondary dissolution stage, and the rock microstructure change model under a salt–CO2 environment was established. The mechanics, temperature, chemical interaction mechanism and fracture propagation mechanism of sandstone under a salt–CO2 environment are discussed. [ABSTRACT FROM AUTHOR]

Six new triterpenoids, heritieras C–H (1–6), along with thirteen known triterpenoids (7–19), were isolated from the leaves of Heritiera littoralis. Their structures were identified by spectroscopic analysis, including 1D and 2D nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectrometry (HRESIMS), and by comparison with the literature. Anti-inflammatory activity of the isolates was evaluated using the lipopolysaccharide (LPS) stimulated RAW 264.7 cell model. Among the isolated triterpenoid, compounds 1, 12, 16, 17, and 18 demonstrated inhibitory activity against nitric oxide (NO) release, in which compound 18 exhibited the best activity with an IC50 value of 18.13 μM. The potential anti-inflammatory mechanism was investigated using molecular docking. The triterpenoids from H. littoralis could be served as potential candidates for the development of new anti-inflammatory agents. [ABSTRACT FROM AUTHOR]

Coronary heart disease (CHD) is the leading cause of morbidity and mortality worldwide despite significant improvements in diagnostic modalities. Emerging evidence suggests that erythrocytes, or red blood cells (RBCs), are one of the most important contributors to the events implicated in atherosclerosis, although the molecular mechanisms behind it are under investigation. We used NMR-based lipidomic technology to investigate the RBC lipidome in patients with CHD compared to those with normal coronary arteries (NCAs), all angiographically documented, and its correlation with coronary artery stenosis. Targeted and untargeted lipidomic analysis revealed that CHD patients presented significant lipid alterations in the RBC membrane, characterized by higher cholesterol, sphingolipids, saturated and monounsaturated fatty acids, lower phospholipids (glycerophospholipids and ether glycerolipids), and unsaturated and polyunsaturated fatty acids. These aberrations gradually distinguish the three subgroups of patients with mild, moderate, and severe coronary stenosis, potentially indicating their non-negligible involvement in the onset and progression of atherosclerosis. The comprehensive analysis of RBC-membrane-derived lipids with omics approaches could unravel specific lipid abnormalities taking place at the silent subclinical stage of atherosclerosis and could have the potential to identify patients with subtle, but still proatherogenic, abnormalities that may confer a higher risk for the development of CHD. [ABSTRACT FROM AUTHOR]

This study introduces a novel water-insoluble dispersant for coal water slurry (CWS), namely, a poly(sodium styrene sulfonate)-grafted SiO2 nanoparticle (SiO2-g-PSSNa). SiO2-g-PSSNa was synthesized by combining the surface acylation reaction with surface-initiated atom transfer radical polymerization (SI-ATRP). Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS), nuclear magnetic resonance spectroscopy (NMR) and thermogravimetric analysis (TGA) verified that SiO2-g-PSSNa with the desired structure was successfully obtained. Afterwards, the performance of SiO2-g-PSSNa as a dispersant in CWS preparation was evaluated. The results indicated that the optimal dosage of SiO2-g-PSSNa was 0.3%. Compared to the famous commercial products, PSSNa and lignosulfonate (LS), SiO2-g-PSSNa exhibits improved viscosity reduction performance. When SiO2-g-PSSNa was used as the dispersant, the maximum coal loading of CWS was 64.2%, which was higher than LS (63.4%) and PSSNa (63.9%). All CWSs obtained in this study were pseudoplastic fluids and more consistent with the Herschel–Bulkley rheological model. The turbiscan stability index (TSI) of CWS prepared with SiO2-g-PSSNa was 0.05, which was significantly lower than CWSs obtained from PSSNa (0.30) and LS (0.36). Therefore, SiO2-g-PSSNa also exhibits excellent stability performance. This result was confirmed by rod penetration tests. The underlying mechanism was also clarified by various measurements, such as contact angle, zeta potential, EDS and low-field nuclear magnetic resonance spectra (low-field NMR). The results reveal that SiO2-g-PSSNa can adsorbed onto the coal surface. SiO2-g-PSSNa possesses a special branched structure, which bears a higher charge density as compared to linear ones with approximate chemical composition. As a result, coal particles adsorbed with SiO2-g-PSSNa exhibit more electronegativity. With the enhancement of the electrostatic repulsive between coal particles, the apparent viscosity was lowered and the static stability was improved. This study demonstrated that solubility in water is not an essential factor in engineering the dispersant. Densely charged groups are probably more important. [ABSTRACT FROM AUTHOR]

Background: In this study, two chalcone analogs were synthesized through in silico and experimental methods, and their potential to inhibit the lipoxygenase enzyme, which plays a role in the inflammation pathway, was assessed. Specifically, this study is a continuation of previous research in which chalcone derivatives were synthesized and characterized. Objectives/Methods: In the current work, we present the re-synthesis of two chalcones, with a focus on their docking studies, NMR analysis, and dynamic simulations. The structure of each chalcone was elucidated through a combination of Nuclear Magnetic Resonance (NMR) and Density Functional Theory (DFT). The substituent effect on the absorption spectrum of the two chalcone derivatives was studied. Results: A "LOX–chalcone" complex, predicted by docking studies, was further examined using molecular dynamics (MD) simulations to evaluate the stability of the complex. After fully characterizing the "LOX–chalcone" complexes in silico, the atomic details of each chalcone's interaction with LOX-1 and 5-LOX were revealed through Saturation Transfer Difference (STD) NMR (Nuclear Magnetic Resonance). Finally, their selectivity profile was investigated against human 15-LOX-1 and general Lipoxidase activity. Conclusions: The in silico methods suggest that chalcones could be promising lead compounds for drug designs targeting the LOX enzyme. [ABSTRACT FROM AUTHOR]

Background/Objectives: Reference materials are essential for ensuring the accuracy and traceability of measurements in the quality control of medicinal products. This study explores new principles for the preparation of impure materials of active pharmaceutical substances, focusing on 1-(3-benzoylphenyl)ethanone ketoprofen impurity A (European Pharmacopoeia) as the reference material. Methods: The reference material was synthesised from commercially available acetanilide and benzoyl chloride. The obtained product was purified using preparative chromatography and characterised by infrared spectroscopy (IR), 1H and 13C nuclear magnetic resonance (NMR), and mass spectrometry. The structure was verified using primary research methods to confirm its identity as the target product. Results: The characterisation confirmed the structure and purity of 1-(3-benzoylphenyl)ethanone, achieving a purity of 99.86%, meeting regulatory documentation requirements. The synthesised product was demonstrated to be identical to the target compound and suitable for use as a reference material. Conclusions: The developed method provides a robust approach for the preparation and characterisation of 1-(3-benzoylphenyl)ethanone, enabling its use as a certified reference material in the quality control of medicinal products. This approach ensures compliance with regulatory standards and enhances the reliability of pharmaceutical quality assurance practices. [ABSTRACT FROM AUTHOR]

Thrombin binding aptamer (TBA) is one of the best-known G-quadruplex (G4)-forming aptamers that efficiently binds to thrombin, resulting in anticoagulant effects. TBA also possesses promising antiproliferative properties. As with most therapeutic oligonucleotides, chemical modifications are critical for therapeutic applications, particularly to improve thermodynamic stability, resistance in biological environment, and target affinity. To evaluate the effects of nucleobase and/or sugar moiety chemical modifications, five TBA analogues have been designed and synthesized considering that the chair-like G4 structure is crucial for biological activity. Their structural and biological properties have been investigated by Circular Dichroism (CD), Nuclear Magnetic Resonance (NMR), native polyacrylamide gel electrophoresis (PAGE) techniques, and PT and MTT assays. The analogue TBAB contains 8-bromo-2′-deoxyguanosine (B) in G-syn glycosidic positions, while TBAL and TBAM contain locked nucleic acid guanosine (L) or 2′-O-methylguanosine (M) in G-anti positions, respectively. Instead, both the two types of modifications have been introduced in TBABL and TBABM with the aim of obtaining synergistic effects. In fact, both derivatives include B in syn positions, exhibiting in turn L and M in the anti ones. The most appealing results have been obtained for TBABM, which revealed an interesting cytotoxic activity against breast and prostate cancer cell lines, while in the case of TBAB, extraordinary thermal stability (Tm approximately 30 °C higher than that of TBA) and an anticoagulant activity higher than original aptamer were observed, as expected. These data indicate TBAB as the best TBA anticoagulant analogue here investigated and TBABM as a promising antiproliferative derivative. [ABSTRACT FROM AUTHOR]

In this experiment, the excellent coordination ability of sulfur-containing ligands was utilized. Diphenylacetyl disulfide and 3,3′-diaminodiphenyl sulfone were selected as ligands, and Cu(NO3)2·3H2O, Ni(NO3)2·6H2O and ZnCl2 were reacted under one-pot conditions to synthesize three mononuclear complexes: [C4H18CuO12S2](I), [C12H18N4NiO11S](II) and [C24H24Cl2N4O4S2Zn](III). Complex (I) belongs to the orthorhombic crystal system with space group Pbca, while complexes (II) and (III) belong to the monoclinic crystal system with space groups P21/n and P2/n. The crystal structure of the complex was determined using X-ray diffraction (XRD). The structure of the complex was analyzed using infrared Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), nuclear magnetic resonance (NMR), and electrospray mass spectrometry (ESI-MS), and the thermal stability and composition of the complex were detected via thermogravimetry (TGA). In terms of application, the biological activity of complexes (I)–(III) in human cancer cell lines (lung cancer A549, liver cancer SMMC-7721, breast cancer MDA-MB-231, and colon cancer SW480) was tested using the MTS method. The results showed that complex (II) had a good inhibitory effect on breast cancer MDA-MB-231. [ABSTRACT FROM AUTHOR]

Human heat shock protein 90 (Hsp90) is one of the most important chaperones that play a role in the late stages of protein folding. Errors in the process of the chaperone cycle can lead to diseases such as cancer and neurodegenerative diseases. Therefore, the activity of Hsp90 must be carefully regulated. One of the possibilities is allosteric regulation by its natural allosteric modulators—nucleotides, co-chaperones and client proteins—and synthetic small-molecule allosteric modulators, such as those targeting the middle domain or the C-terminal domain (CTD) of Hsp90. Since no experimentally determined structure of a small-molecule allosteric modulator bound to the CTD of human Hsp90 has yet been obtained, the challenge for a structure-based design of allosteric modulators remains. Solution nuclear magnetic resonance (NMR) spectroscopy could be utilized to overcome these problems. The main aim of this review article is to discuss how solution NMR techniques, especially protein-based, and the advanced isotope labeling of proteins have been used to investigate the allosteric regulation of the cytosolic isoforms of human Hsp90 with allosteric modulators. This article provides the basis for planning future NMR experiments, with the aim of gaining insights into allosteric sites and the mechanisms of allosteric regulation. [ABSTRACT FROM AUTHOR]

The influence of different pore sizes on the compressive strength and elastic modulus of recycled concrete is an important issue in the academic circle. Aiming at this problem, a quantitative characterization model of the compressive strength and elastic modulus of recycled concrete based on pore grading was established in this paper. The compressive strength, elastic modulus, porosity and distribution of pore size of recycled concrete were measured by a concrete test and nuclear magnetic resonance technology, and the influences of different pore sizes on the compressive strength and elastic modulus of recycled concrete were analyzed, and the rationality of the quantitative characterization model was verified. The results showed that the compressive strength and elastic modulus of recycled concrete decreased with the increase in the recycled coarse aggregate replacement rate, and the decrease was more obvious with the increase in the substitution rate. The peak pore diameter in the distribution curve of porosity and pore diameter of recycled concrete increased, and the proportion of pore diameter above 50~200 nm and 200 nm also increased. The pore sizes, including those below 20 nm and 20~50 nm, had a positive correlation with the compressive strength and elastic modulus of recycled concrete, while the pore sizes, including those above 50~200 nm and 200 nm, had a negative correlation with the compressive strength and elastic modulus of recycled concrete. The test results of recycled concrete verify that the quantitative characterization model could better characterize the compressive strength and elastic modulus of recycled concrete. [ABSTRACT FROM AUTHOR]

The precise identification of maize kernel varieties is essential for germplasm resource management, genetic diversity conservation, and the optimization of agricultural production. To address the need for rapid and non-destructive variety identification, this study developed a novel interpretable machine learning approach that integrates low-field nuclear magnetic resonance (LF-NMR) with morphological image features through an optimized support vector machine (SVM) framework. First, LF-NMR signals were obtained from eleven maize kernel varieties, and ten key features were extracted from the transverse relaxation decay curves. Meanwhile, five image morphological features were selected using the recursive feature elimination (RFE) algorithm. Before modeling, principal component analysis (PCA) was used to determine the distribution features of the internal components for each maize variety. Subsequently, LF-NMR features and image morphological data were integrated to construct a classification model and the SVM hyperparameters were optimized using an improved differential evolution algorithm, achieving a final classification accuracy of 96.36%, which demonstrated strong robustness and precision. The model's interpretability was further enhanced using Shapley values, which revealed the contributions of key features such as Max Signal and Signal at Max Curvature to classification decisions. This study provides an innovative technical solution for the efficient identification of maize varieties, supports the refined management of germplasm resources, and lays a foundation for genetic improvement and agricultural applications. [ABSTRACT FROM AUTHOR]

Background: The increasing prevalence of drug-resistant tuberculosis (TB) underscores the urgent need for novel antimicrobial agents. Methods: This study integrates cultivation optimization, nuclear magnetic resonance (NMR) fingerprinting, and principal component analysis (PCA) to explore microbial secondary metabolites as potential anti-TB agents. Results: Using the combined approach, 11 bioactive compounds were isolated and identified, all exhibiting anti-Mycobacterium bovis BCG activity. Notable findings include borrelidin, a potent threonyl-tRNA synthetase inhibitor with broad biological activities, and L-O-Lac-L-Val-D-O-Hiv-D-Val, a peptide isolated for the first time from a plant endophyte, demonstrating broad-spectrum antimicrobial activity. Additionally, elaiophylin and polycyclic tetramate macrolactams (PTMs) displayed significant bactericidal effects, with elaiophylin achieving complete BCG inhibition at 72 h and PTMs marking their first reported anti-TB activity. The study also identified bafilomycins as potent scaffolds for anti-TB drug development, showcasing rapid bactericidal activity at low MIC values. Conclusions: These findings emphasize the value of microbial metabolites as a reservoir of bioactive compounds and provide new avenues for developing next-generation anti-TB therapies. [ABSTRACT FROM AUTHOR]

The various forms of anthropogenic pollution are regarded as a serious threat to marine coastal areas. The overproduction and mismanagement of petroleum derivatives, such as tar and plastics, have resulted in a significant correlation between these two pollutants. The aggregation of tar, microplastics (MPs), and natural materials can create plastitar blocks, which are common in coastal areas. These raise concern about the undeniable negative impact on the marine ecosystem and the associated biota, and serve as a recognizable and understandable indication of environmental decline. Here, the composition of the 11 plastitar blocks collected on the Ionian side of the Apulia region (Italy) was characterized both in tar and plastics using nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy, respectively. Of the 250 particles extracted from the tar, 208 were identified as plastics, predominantly Polyethylene. The majority of these were in the form of pellets (90%), with fragments accounting for 5% and films and filaments representing the remaining 5%. This study provides new data that can be used to enhance the understanding of the distribution and baseline information about this novel form of pollution in Italian waters. [ABSTRACT FROM AUTHOR]

To investigate the molecular structure characteristics and chemical reaction mechanisms of gas coal from the Hong II coal mine of the Ningxia Hongdunzi Coal Industry, this study explores its elemental composition, structural features, and methods for constructing and optimizing molecular models. The basic properties of the coal were determined through proximate and elemental analyses. The carbon structure was characterized using 13C-NMR nuclear magnetic resonance, the N and S chemical states were analyzed with XPS, and the distribution of hydroxyl, aliphatic hydrocarbons, aromatic rings, and oxygen-containing functional groups was characterized by FT-IR. Based on the analysis results, a molecular structure model of Hongdunzi gas coal was constructed with the molecular formula C204H117O17NS, and the calculated results of the model showed high consistency with the experimental spectra of 13C-NMR. The macromolecular model of gas coal was constructed using the Materials Studio 2020 software, and its structure was optimized through geometric optimization and dynamic simulations. After optimization, the total energy of the model was significantly reduced from 8525.12 kcal·mol−1 to 3966.16 kcal·mol−1, highlighting the enhanced stability of the coal molecular structure. This optimization indicates that torsional energy plays a dominant role in molecular stability, while van der Waals forces and electrostatic interactions were significantly improved during the optimization process. [ABSTRACT FROM AUTHOR]

Investigating the imbibition characteristics of coals can yield profound insights for advancing coalbed methane extraction and utilization strategies. However, there has been little exploration of the micro-pore imbibition phenomenon during the two-phase flow of gas and water, as research has focused more on the process of static imbibition. In this study, we used an independently developed low-field nuclear magnetic resonance (NMR) displacement experimental device to conduct a systematic study on the dynamic imbibition phenomenon of low-permeability coals under conditions in which gas and water coexist. The experimental results show that the imbibition process under conditions of gas–water coexistence was significantly influenced by the physical properties of the coal samples, such as the wetting contact angle, porosity, and permeability. A smaller wetting contact angle and lower porosity and permeability values were indicative of a stronger imbibition effect. Meanwhile, changes in effective stress and pore pressure had a significant effect on the imbibition process. Changes in effective stress were observed to elastically compress (or expand) the coal pores, leading to intensified (or weakened) imbibition. Greater pore pressure led to a more violent imbibition reaction. These findings provide a new theoretical basis for understanding and predicting imbibition phenomena in the two-phase flow of gas and water in coalbed methane engineering, offering the potential to illuminate the intricate self-absorption phenomena occurring during CO2 geological sequestration processes. [ABSTRACT FROM AUTHOR]

Synthetic peptides are commonly obtained by means of solid-phase peptide synthesis (SPPS), in which separation of the peptide from the solid support requires treatment with 92.5% v/v trifluoroacetic acid (TFA); therefore, peptides are obtained as trifluoroacetate salts. For promising anticancer/antibacterial peptides it is essential to exchange the counterion from trifluoroacetate to hydrochloride or acetate, since the former are more widely studied in biological activity assays. In this research, RP-SPE-based methodologies were designed, developed, and implemented for simultaneous counterion exchange and peptide purification. Critical process steps were identified and parameters such as mobile phase composition, elution, and program were optimized. Analysis of the counterion exchange reaction and characterization of the final products was performed using high-performance liquid chromatography, attenuated total reflectance, nuclear magnetic resonance, and mass spectrometry. Peptides with purities between 82–97% and a trifluoroacetate ion content less than 0.36% were obtained. This novel counterion exchange proved efficient for peptides with different characteristics such as length, polarity, polyvalency, and presence of non-natural amino acids or non-protein molecules, therefore showing a wide range of applications in the field of therapeutic peptides. The methods developed are fast, efficient, low-cost, and do not require robust instrumentation and can be routinely implemented in SPPS. [ABSTRACT FROM AUTHOR]

Qualitative and quantitative differences in the chemical composition between bee pollen originated from Castanea sativa (Türkiye and Slovenia), Salix spp. (Türkiye and Slovenia), and Quercus spp. (Türkiye) and androecia of Castanea sativa, Salix alba, and Quercus pubescens (apetalous trees) were evaluated for the first time by new high-performance thin-layer chromatography (HPTLC) and ultra-performance liquid chromatography (UPLC) methods using marker compounds. N1,N5,N10-tricaffeoylspermidine was isolated, and its structure was elucidated by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). It was the main and the marker compound common to bee pollen (≈3–41 mg/g) and androecia (≈3–6 mg/g) samples. To the best of our knowledge, this is the first report of the identification of N1,N5,N10-tricaffeoylspermidine in bee pollen originated from Salix spp. and androecia of C. sativa, S. alba, and Q. pubescens. The botanical origins of bee pollen were determined via phytochemical profiling using HPTLC-image analyses showing that bee pollen from the same botanical source had almost identical profiles regardless of collection location, geographical differences, and the bee race. In vitro tests and HPTLC-effect-directed analyses (EDAs) were performed to assess antioxidant and xanthine oxidase (XO) inhibitory activities of bee pollen, androecia, and N1,N5,N10-tricaffeoylspermidine. HPTLC-EDA combined with image analyses was used for comparing the activities of bee pollen, androecia, N1,N5,N10-tricaffeoylspermidine, and also other marker compounds (quercetin, myricitrin, hyperoside, quercitrin, isoquercitrin, and rutin). The remarkable bioactivity of N1,N5,N10-tricaffeoylspermidine was for the first time evaluated by HPTLC-EDA and in vitro tests. This is the first study performing HPTLC-XO inhibitory activity analyses on the HPTLC NH2 F254S plates. Further bioactivity studies on botanically and chemically well-characterized bee pollen samples are needed to aid in the use of bee pollen-containing supplements in the prevention and treatment of diseases. [ABSTRACT FROM AUTHOR]

The porosity structure of rocks is an important research topic in fields such as civil engineering, geology, and petroleum engineering, with significant implications for groundwater flow, oil and gas reservoir exploitation, and geological hazard prediction. This paper systematically explores the research progress and knowledge graph construction methods for rock porosity structure, aiming to provide scientific foundations for a multidimensional understanding and application of rock porosity structure. It outlines the basic concepts and classifications of rock porosity, including the definitions and characteristics of macropores, micropores, and nanopores. This paper provides a comprehensive overview of the main technical methods employed in recent research on rock porosity structure, including X-ray computed tomography, scanning electron microscopy, nuclear magnetic resonance, and 3D reconstruction technologies. It explores the relationship between porosity structure and the physical and mechanical properties of rocks, focusing on the impact of porosity, permeability, and pore morphology on rock mechanical behavior. A knowledge graph of rock porosity structure is constructed to highlight key research areas, core technologies, and emerging applications in this field. The study utilizes extensive literature review and data mining techniques, analyzing 4807 papers published over the past 20 years, sourced from the Web of Science database. Bibliometric and knowledge graph analyses were performed, examining trends such as annual publication volume, country/region distribution, institutional affiliations, journal sources, subject categories, and research databases, as well as research hotspots and frontier developments. This analysis offers valuable insights into the current state of rock porosity structure research, shedding light on its progress and providing references for further advancing research in this area. [ABSTRACT FROM AUTHOR]

The oleoresin and volatile fraction produced by conifers, such as Pinus pinaster, play a crucial role in plant defence, acting as precursors to resin acids and adapting in response to environmental stress or pathogen attacks. Abietadiene (abieta-7,13-diene), the biosynthetic precursor to abietic acid, has been identified as the most abundant compound in extracts from pinewood nematode (PWN)-infected P. pinaster trees. As abietadiene is not commercially available, this study aimed to achieve, for the first time, its isolation, structure elucidation, and detailed characterization from readily available forestry residues. Abietadiene was successfully isolated using thin-layer chromatography (TLC), and its purity and identity were evaluated using multiple analytical techniques: gas chromatography (GC), liquid chromatography (LC), nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FTIR). GC analysis indicated a purity of over 70% for the isolated compound, while LC provided the higher purity value of 98%. The identity of abietadiene was unequivocally confirmed through LC, FTIR, and NMR analysis. This work represents the first isolation and comprehensive characterization of abietadiene from a natural source, making detailed chemical data on this compound available to the scientific community. These findings may be used for future studies on the biological interactions and ecological roles of abietadiene, particularly in the context of plant defence and pathogen resistance. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) spectroscopy is gaining prominence as a vital quantitative method for sample analysis, with significant progress being made in the investigation of heteronuclei like phosphorus, a key element in numerous physiological functions. This paper provides a comprehensive review of the principles, methodologies, and applications of quantitative 31P nuclear magnetic resonance (qNMR) spectroscopy. It begins with an introduction to the fundamental principles of NMR spectroscopy, highlighting the specific advantages of qNMR and the unique properties of the 31P nucleus, including its high natural abundance and broad chemical shift range. While 1H qNMR is widely used, signal overlap in complex mixtures can limit its accuracy. Additionally, this work explores diverse applications of 31P qNMR across fields such as food analysis, pharmaceuticals, and biology, emphasizing its contributions to real-time drug quantification, metabolomics, and environmental analysis. A key advantage of 31P NMR is its ability to provide exclusive detection and direct quantification of phosphorus in phosphorus-containing compounds. The internal standard method is favored for its simplicity, as it avoids the need for calibration curves, while the external standard method is better suited for natural products with established reference materials. This review aims to consolidate the applied prospects of 31P qNMR, emphasizing its potential to expand the horizons of quantitative detection technologies and facilitate advancements in future research and practical applications. [ABSTRACT FROM AUTHOR]

Microwave-assisted rock breaking is recognized as an effective technology for reducing tool wear and enhancing rock-breaking efficiency. In this study, basalt rock was irradiated with a microwave power of 3 kW and 6 kW for 30 s, 60 s, 90 s, and 120 s. Subsequently, uniaxial compression, uniaxial loading and unloading, and acoustic emission tests were performed. The damage evolution of basalt was assessed through non-destructive acoustic testing methods and nuclear magnetic resonance (NMR) techniques. The results showed that the P-wave velocity, uniaxial compressive strength (UCS), and modulus of elasticity (E) exhibited varying degrees of deterioration as the microwave radiation time increased. An increase in microwave radiation time and power led to heightened acoustic emission activity in basalt and a significant rise in the proportion of shear cracks during uniaxial compression. From an energy perspective, microwave irradiation decreased the energy storage capacity of the basalt specimen prior to its peak point, with increased power and duration. At a microscopic level, porosity and the macroporous fractal dimension increased with extended microwave radiation time and power, indicating that microwave irradiation facilitated the growth of larger fractal pore structures. The findings of this study offer scientific insights for the application of microwave-assisted rock crushing. [ABSTRACT FROM AUTHOR]

This study investigates the effect of microstructural changes in polyurethane coatings on their water resistance properties. Polyurethane coatings with varying diluent contents were prepared and tested for water penetration resistance and mechanical property retention. The time-dependent behavior of water within the coatings at different immersion durations was analyzed using low-field nuclear magnetic resonance (NMR). Furthermore, the free volume and characteristic molecular groups of each coating were analyzed using microscopic techniques, including positron annihilation lifetime spectroscopy (PALS) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR−FTIR). Results indicate that diluent content significantly alters the microstructure of the coatings. With increasing diluent content, both the average pore volume and free volume fraction initially decrease and then increase, while characteristic molecular groups, including hydrophilic groups, gradually decline. The water resistance performance of the coatings was significantly influenced by the combined effects of free volume and characteristic molecular groups. Among the five tested coating formulations, coatings with diluent contents of 20% and 25% showed a superior water penetration resistance, higher retention of mechanical properties after immersion, and relatively low total content of bound and free water at all immersion ages. The entropy weight method and the equal weight method were used to assess the overall water resistance, with the following ranking of scores: f20 > f25 > f30 > f15 > f10. This study offers theoretical support to guide the design and practical application of polyurethane coatings in real-world engineering projects. [ABSTRACT FROM AUTHOR]

Well-defined amorphous/semi-crystalline statistical copolymers of n-dodecyl isocyanate, DDIC, and allyl isocyanate, ALIC, were synthesized via coordination polymerization using the chiral half-titanocene complex CpTiCl2(O-(S)-2-Bu) as an initiator. In the frame of the terminal model, the monomer reactivity ratios of the statistical copolymers were calculated using both well-known linear graphical methods and the computer program COPOINT. The molecular and structural characteristics of the copolymers were also calculated. The thermal properties of these samples were studied by differential scanning calorimetry, DSC, measurements. The kinetics of the thermal decomposition of the statistical copolymers was studied by thermogravimetric analysis, TGA, and differential thermogravimetry, DTG, and the activation energy of this process was calculated by employing several theoretical models. Moreover, block copolymers with the structure P[DDIC-b-(DDIC-co-ALIC)] were synthesized by sequential addition of monomers and coordination polymerization methodologies. The samples were characterized by nuclear magnetic resonance, NMR, spectroscopy; size exclusion chromatography, SEC; and DSC. The thermal stability of the blocks was also studied by TGA and DTG and compared to the corresponding statistical copolymers, showing that the macromolecular architecture greatly affects the properties of the copolymers. A thiol-ene click post-polymerization reaction was performed to introduce aromatic groups along the polyisocyanate chain in order to improve the thermal stability of the parent polymers. Evidently, these statistical and block copolymers can be employed as precursors for the synthesis of novel polyisocyanate-based materials. [ABSTRACT FROM AUTHOR]

A series of novel amphiphilic alternating CPEG copolymers were synthesized through an amine–epoxy click reaction comprising aliphatic amine and polyethylene glycol diglycidyl ether (PEGDE). These polymers were characterized in detail via nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to confirm the successful synthesis. Due to their amphiphilic structure, these polymers display thermoresponsiveness, with tunable cloud points (Tcps) that are adjustable from 20.8 °C to 46.8 °C by altering the side-chain length of the aliphatic amine, varying the mixing ratios of copolymers, the solution's pH, and salt additions. This tunable thermoresponsive behavior positions CPEG copolymers as promising candidates for a range of functional material applications. [ABSTRACT FROM AUTHOR]

This study explored the effect of the combined application of chemical and organic fertilizers on phosphorus morphology and its conversion to an active state. A long-term field positioning experiment comprising five treatments was conducted in black soil. The results concluded that the soil total phosphorus (TP), available phosphorus (AP), inorganic phosphorus, and organic phosphorus contents of all treatments ranked as follows: 1.5M1NPK > M2NPK > M1NPK > NPK > CK. The long-term application of chemical and organic fertilizers increased the proportion of soil reactive phosphorus and moderately reactive phosphorus but decreased the proportion of mildly active phosphorus and residual phosphorus. A phosphorus-31 nuclear magnetic resonance (31P NMR) spectral analysis showed that the contents of orthophosphate, pyrophosphate, phosphoric acid diesters, and orthophosphate acid monoesters increased with the application of chemical and organic fertilizers, of which 1.5M1NPK usually resulted in the highest increases. In conclusion, the long-term application of chemical fertilizers could promote the conversion of soil phosphorus into active phosphorus and improve the effectiveness of soil phosphorus, and the long-term use of organic and chemical fertilizers was more effective than the use of chemical fertilizers only, with 1.5M1NPK providing the best effects. [ABSTRACT FROM AUTHOR]

Featured Application: Poly(acrylic acid)/poly(acrylamide) microgels with an IPN structure demonstrate smart behavior with dual pH and temperature responsiveness. Both factors are determinative for human physiology. This, combined with the anionic nature of these microgels, determines their potential as a suitable carrier for the drug delivery of cationic drugs through the gastro-intestinal tract. Microgels with precisely tuned properties are of great importance as drug delivery systems. Here, we report the synthesis of microgel particles (MGs) with an interpenetrating polymer network structure composed of poly(acrylic acid) (PAA) and polyacrylamide (PAAM) for their potential application as cationic drug carriers. The MG properties were investigated via several analytical techniques, such as Dynamic Light Scattering (DLS) and zeta potential (ZP) measurements, Diffusion Nuclear Magnetic Resonance (NMR) spectroscopy, Asymmetrical Flow Field-Flow Fractionation (AF4) and Transmission Electron Microscopy (TEM). The MGs show pH-dependent swelling behavior with a radius of ~100 nm at collapsed state (pH < 4.5) and swell up to ~450 nm (pH~7), while their ZP decreases from −5 to −40 mV, depending on their composition. The results of the conducted studies demonstrate the potential of synthesized microgels for drug delivery in the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Featured Application: Rapid and Non-Invasive Determination of Iodine Value in Commercial Edible Oils. This study presents a fast, non-invasive method to determine the iodine value (IV) of edible oils using Time Domain Nuclear Magnetic Resonance (TD-NMR) and Magnetic Resonance Imaging (MRI) techniques. The IV, which quantifies the degree of unsaturation in fats and oils, is a key parameter in assessing oil quality and detecting potential adulteration. Different edible oils were used in this study (sunflower, soy, olive, sesame, and linseed). Statistically significant regression models (R2 > 0.92) were established between the IV derived from NMR spectra and the longitudinal (T1) and transverse (T2) relaxation times of the oils, which were obtained from MRI and TD-NMR analyses. The regression models obtained allow for the prediction of the IV from the T1 and T2 relaxation times across a range that includes predominantly mono- and polyunsaturated edible vegetable oils. The TD-NMR approach stands out for its speed (<2 min), lack of sample preparation (including direct analysis within the commercial packaging), and reproducibility, with a variability of only 0.62%. Meanwhile, the MRI technique allows for the simultaneous evaluation of multiple samples in a single acquisition. Together, these features make TD-NMR and MRI effective tools for the rapid and reliable analysis of the IV in edible oils. [ABSTRACT FROM AUTHOR]

In this study, Undaria pinnatifida (UP) was used as the primary research material, and sugar-free gummy jelly was prepared using ultraviolet (UV) irradiation with phycocyanin. The properties were measured using a texture analyzer, color difference analyzer, low-field nuclear magnetic resonance (LF-NMR) analyzer, and sensory evaluation. Additionally, the stability during accelerated storage was examined. The results showed that UV irradiation-assisted phycocyanin significantly increased the hardness of the sugar-free gummy jelly, from 268.4 ± 11.0 g to 477.9 ± 5.2 g, and enhanced its chewiness, from 247.4 ± 12.2 to 415.1 ± 3.1. Additionally, the jelly exhibited stronger water binding ability, with the proportion of immovable water increasing from 6.17 ± 0.66% to 9.52 ± 0.77%. During accelerated storage, the texture properties, color, water migration, and phycocyanin content of the sugar-free gummy jelly were changed. However, UV irradiation-assisted phycocyanin treatment slowed down the changes in the texture, color, and phycocyanin content of the sugar-free gummy jelly, which indicated that the product had good stability during storage. These results enhance the application of UP in sugar-free gummy jellies. [ABSTRACT FROM AUTHOR]

The study of the fractal characteristics of the pore throat radius (PTR) and throat radius of sweet spots is crucial for the exploration and development of tight gas sandstone. This study used conventional core analysis, X-ray diffraction analysis, scanning electron microscopy (SEM), and constant-rate mercury injection experiment (CRMI), high-pressure mercury injection experiment (HPMI), and nuclear magnetic resonance (NMR) techniques to investigate the fractal characteristics of the PTR and throat radius of the tight sandstone sweet spots of the Huagang Formation in the central uplift belt of the East China Sea Basin. Based on conventional core analysis and SEM, the main pore types of the tight sandstone samples in the Huagang Formation were determined to be intergranular dissolved pore, intragranular dissolved pore, intergranular pore, and moldic pore. HPMI and NMR techniques were used to evaluate the full-size PTR distribution of type I (TI), type II (TII), and type III (TIII) sweet spots. Based on fractal theory, CRMI was used to calculate the fractal dimension of the PTR and throat radius of three types of sweet spots, and the relationship between the fractal dimensions and pore throat structure parameters and mineral composition were investigated. The results showed that the full-size PTR distribution curve exhibited bimodal or unimodal characteristics. The peak values of the PTR distribution of the TI, TII, and TIII sweet spots were mainly concentrated at 0.002–22.5 μm, 0.001–2.5 μm, and 0.0004–0.9 μm, respectively. The fractal dimensions of the PTR and throat radius were calculated. The average throat radius fractal dimensions of the TI, TIII, and TIII sweet spots were 2.925, 2.875, and 2.786, respectively. The average PTR fractal dimensions of the TI, TII, and TIII sweet spots were 2.677, 2.684, and 2.702, respectively. The throat radius fractal dimension of the TI, TII, and TIII sweet spots was positively correlated with mercury saturation, average throat radius, feldspar content, and clay mineral content and negatively correlated with displacement pressure, quartz content, and carbonate cement content. The PTR fractal dimension of the TI, TII, and TIII sweet spots was positively correlated with displacement pressure, quartz content, and carbonate cement content and negatively correlated with feldspar content. The throat size of the TI sweet spot was large, and the heterogeneity of the throat was strong. The PTR heterogeneity of the TI sweet spot was lower than that of the TII and TIII sweet spots. The findings of this study can provide important guidance for the exploration and development of tight gas sandstone. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of novel sulfamethoxazole organotin complexes and evaluates their potential for hydrogen storage applications. The synthesized complexes were characterized using various techniques, such as Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy to determine their constructional and physicochemical properties. Field Emission Scanning Electron Microscopy was applied to analyze the surface morphology, and the Brunauer–Emmett–Teller method was utilized to measure the surface area. High-pressure adsorption experiments demonstrated the remarkable hydrogen storage capabilities of these complexes, with the highest hydrogen uptake of 29.1 cm3/g observed at 323 K. The results suggest that the prepared sulfamethoxazole organotin complexes have the potential to be candidates for gas separation and storage applications. [ABSTRACT FROM AUTHOR]

Definition: 1H High-Resolution Nuclear Magnetic Resonance (1H HR-NMR) spectroscopy is a powerful analytical methodology used in various fields, including food science. In the food science field, NMR combined with the principles of metabolomics can provide detailed information about a food's molecular composition, structure, dynamics, and interactions within food matrices, making it invaluable for assessing changes during storage, processing, and shelf life. This entry aims to list the main applications of one-dimensional 1H HR-NMR methods in the field of food science, such as their use in the assessment of the stability, quality, authenticity, and shelf life of food samples. Several kinds of foods are taken into consideration to give a huge overview of the potentiality of the methods. [ABSTRACT FROM AUTHOR]

This review explores the current applications of artificial intelligence (AI) in nuclear magnetic resonance (NMR) spectroscopy, with a particular emphasis on small molecule chemistry. Applications of AI techniques, especially machine learning (ML) and deep learning (DL) in the areas of shift prediction, spectral simulations, spectral processing, structure elucidation, mixture analysis, and metabolomics, are demonstrated. The review also shows where progress is limited. [ABSTRACT FROM AUTHOR]

Cataracts are diseases characterized by the opacity of the ocular lens and the subsequent deterioration of vision. Metal ions are one of the factors that have been reported to induce crystallin aggregation. For HγS crystallin, several equivalent ratios of Cu(II) promote protein aggregation. However, reports on zinc are contradictory. To characterize the process of metal ion binding and subsequent HγS crystallin aggregation, we performed dynamic light scattering, turbidimetry, isothermal titration calorimetry, fluorescence, and nuclear magnetic resonance experiments. The data show that both metal ions have multiple binding sites and promote aggregation. Zinc interacts mainly with the N-terminal domain, inducing small conformational changes, while copper interacts with both domains and induces unfolding, exposing the tryptophan residues to the solvent. Our work provides insight into the mechanisms of metal-induced aggregation at one of the lowest doses that appreciably promote aggregation over time. [ABSTRACT FROM AUTHOR]

Oligo(phenylene ethynylene)s (OPEs) are π-conjugated systems with promising optical, bioactive, and electrical properties, making them valuable candidates for molecular electronics and biosensors. Controlling the arrangement and orientation of π-conjugated systems is crucial in developing molecular devices. Recently, we developed insulated diarylacetylene dimers using a [c2]daisy chain rotaxane strategy, which brings two cores into close proximity without covalent bonding and shields them with permethylated α-cyclodextrins. Here, we synthesized an insulated OPE dimer using a similar rotaxane strategy to investigate its optical properties. The rotaxane structure and optical properties were evaluated using nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization high-resolution mass spectrometry (ESI-HRMS), and absorption and fluorescence spectroscopy. This study is expected to contribute to the development of optical and electronic materials utilizing OPEs. [ABSTRACT FROM AUTHOR]

We herein report the synthesis of a 7-chloro-aminoquinoline triazine conjugate. The s-triazine library was generated by stepwise nucleophilic substitution of cyanuric chloride with butylamine. The structure of the compound was comprehensively determined using various analytical techniques, including proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), heteronuclear single quantum coherence (HSQC), and Distortionless Enhancement by Polarization Transfer (DEPT-135) experiments. Additionally, ultraviolet (UV) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and high-resolution mass spectrometry (HRMS) were employed for full characterization. Preliminary studies explored the potential interaction of the molecule with dihydrofolate reductase (DHFR) using molecular modeling. Furthermore, its drug-likeness was assessed by predicting relevant pharmacokinetic properties. [ABSTRACT FROM AUTHOR]

The huge amount of citrus peel produced worldwide represents an economic burden for society. However, this agricultural by-product is a rich source of natural molecules, potentially endowed with interesting pharmacological activities. In this regard, we decided to investigate if the polymethoxyflavones contained in citrus peel waste could be exploited as novel vasorelaxant agents. A hydroalcoholic blond orange (Citrus sinensis) peel extract, obtained by ultrasonication, was partitioned in dichloromethane. Column chromatography allowed for the isolation of four polymethoxyflavones, namely, scutellarein tetramethyl ether, nobiletin, tangeretin, and sinensetin, identified by nuclear magnetic resonance (NMR) spectroscopy and UPLC-HRMS/MS and confirmed by multivariate curve resolution of NMR fractional spectra. The four molecules showed interesting in vitro vasorelaxant activity, at least, in part, due to the blockade of smooth muscle CaV1.2 channels. Molecular modeling and docking analysis elucidated the binding mode of the polymethoxyflavones at the homology model of the rat CaV1.2c subunit and provided the structural basis to rationalise the highest activity of scutellarein tetramethyl ether in the set and the dramatic effect of the additional methoxy group occurring in nobiletin and sinensetin. In conclusion, citrus peel can be considered a freely available, valuable source of vasoactive compounds worthy of pharmaceutical and/or nutraceutical exploitation. [ABSTRACT FROM AUTHOR]

Gerbera piloselloides, a plant in the Asteraceae family, is a traditional Chinese medicinal herb known for its unique therapeutic properties, including reported anti-tumor and antioxidant effects. Recent studies suggest that the main constitute of G. piloselloides, coumarins, may have potential anti-tumor activity. Recent research suggests that coumarins, the active compounds in G. piloselloides, may hold potential anti-tumor activity. However, the pharmacodynamic constituents remain unidentified. This study aims to isolate and characterize the bioactive compounds of G. piloselloides and to assess its anti-tumor effects. Initially, seven compounds, including coumarins, a ketone, and a furanolide, were isolated and identified from G. piloselloides by semi-preparative high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) analysis. The anti-tumor effects of these compounds were evaluated across four different cancer cell lines. Among them, the compound cyclobrachycoumarin showed a significant inhibitory effect on colorectal cancer (CRC) cell proliferation and was selected for further investigation. Cyclobrachycoumarin was found to induce CRC cell apoptosis and cell cycle arrest in a dose-dependent manner. This treatment also led to increased levels of ROS and cleaved PARP, along with decreased expressions of survivin, cyclin D1, and CDK1. In vivo studies further demonstrated that cyclobrachycoumarin effectively reduced tumor growth in HT-29 xenograft models by promoting apoptosis and cell cycle arrest, with a favorable tolerability profile. In summary, this study suggests that cyclobrachycoumarin may be a promising candidate for safe and effective CRC therapy. [ABSTRACT FROM AUTHOR]

The stem bark of black locust (Robinia pseudoacacia L.) was extracted, and nine antioxidant compounds (R1–R9) were detected by high-performance thin-layer chromatography combined with the radical scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH•) assay, multi-detection, and heated electrospray high-resolution mass spectrometry. For structure elucidation, the methanolic crude extract was fractionated by solid-phase extraction, and the compounds were isolated by reversed-phase high-performance liquid chromatography with diode array detection. The structures of isolated compounds were elucidated by nuclear magnetic resonance and attenuated total reflectance Fourier-transform infrared spectroscopy as well as gas chromatography-mass spectrometry to determine the double bond position. 3-O-Caffeoyl oleanolic acid (R1), oleyl (R2), octadecyl (R3), gadoleyl (R4), eicosanyl (R5), (Z)-9-docosenyl (R6), docosyl (R7), tetracosyl (R8), and hexacosanyl (R9) caffeates were identified. While R1 has been reported in R. pseudoacacia stem bark, the known R3, R5, R7, R8, and R9 are described for the first time in this species, and the R2, R4, and R6 are new natural compounds. All nine caffeates demonstrated antioxidant activity. The antioxidant effects of the isolated compounds R1–R8 were quantified by a microplate DPPH• assay, with values ranging from 0.29 to 1.20 mol of caffeic acid equivalents per mole of isolate. [ABSTRACT FROM AUTHOR]

Effective formation and stabilisation of emulsions while meeting high consumer requirements, including the so-called green label, is still a technological challenge. This is related to the multitude of emulsion destabilization mechanisms and the vastness of methods used to study them, which implies the need to develop an understanding of the phenomena occurring in emulsions. Commercial starch preparations obtained by physical and chemical modification were used to prepare model emulsions that were studied in terms of their stability. Native potato starch was the reference material. The analytical methods used included rheology, low field nuclear magnetic resonance (LF NMR), size exclusion chromatography with triple detection (SEC), and surface/interfacial tension measurements. The results showed that chemical and physical modification improved the functionality of starch in emulsions. This is due to not only chemical but also physical modifications, i.e., pregelatinization causes changes in the molecular structure of starch, including an increase in the molecular weight and the degree of branching. As a consequence, the conformation of starch macromolecules changes, which results in a change of the dynamics of protons in the continuous phase of the emulsion and the thermodynamics of starch adsorption at the water/oil interface. [ABSTRACT FROM AUTHOR]

Based on their various and outstanding properties, binary nitrides are used as (synthesis) materials in industry and research. Hence, their comprehensive characterization by analytical methods is of particular interest. Since Nuclear Magnetic Resonance (NMR) spectroscopy is very sensitive to the symmetry of the electronic density distribution, it is a suitable tool for the investigation of rock-salt structure types and, especially, for those with known stoichiometry issues. Here, we report on magic-angle spinning NMR spectra of the nuclides 89Y ( I = 1 2 ), 139La ( I = 7 2 ) and 14N ( I = 1 ) in polycrystalline samples of YN, LaN and LuN. Due to the high symmetry of their crystal structures, the spectra of all nuclides do not exhibit anisotropic effects of significant magnitude. The resulting isotropic chemical shift values are δ i s o (89Y) = 516 ppm for YN, δ i s o (139La) = 1294 ppm for LaN, and δ i s o (14N) = 457 ppm (YN), 788 ppm (LaN) and 384 ppm (LuN). The newly determined δ i s o (14N) values for these three binary nitrides fit well into the previously reported linear correlation between nitrogen distance to the nearest cation and isotropic chemical shift, leading to a better correlation coefficient and reduced error margins for the fit parameters. [ABSTRACT FROM AUTHOR]

Three new depsipeptides, homiamides A–C (1–3), were isolated from a marine sediment-derived strain of Streptomyces sp., ROA-065. The planar structures of homiamides A–C (1–3) were elucidated using mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopic data. The absolute configurations of 1–3 were deduced from the application of the Marfey's method and GC-MS analysis after formation of the O-trifluoroacetylated (S)-(+)-methyl-2-butyl ester derivatives of amino acids. Compounds 1–3 exhibited weak anti-bacterial activities against both Gram-positive bacteria and Gram-negative bacteria, with compound 1 showing MIC values of 32–64 μg/mL. In antifouling assays, compounds 1 and 2 displayed moderate activity against Micrococcus luteus KCTC 3063, while compound 3 exhibited weak activity against all tested bacteria. [ABSTRACT FROM AUTHOR]

Objectives: The effect of 2-hydroxpropyl-β-cyclodextrin (2HPβCD) with or without divalent metal ions (Ca2+, Mg2+, and Zn2+) on the stability of dalbavancin in acetate buffer was investigated. Methods: Dalbavancin recovery from formulations with 2HPβCD and divalent metal ions after four weeks of storage at 5 °C and 55 °C was measured by RP-HPLC and HP-SEC; a longer-term study was carried out over six months at 5 °C, 25 °C, and 40 °C. Binding of 2HPβCD was characterized by isothermal titration calorimetry (ITC) and nuclear magnetic resonance (NMR). Results: The stability of the dalbavancin formulations after 4 weeks at 55 °C in 10 mM acetate buffer was significantly improved with 0.6 mM, 5.5 mM, and 55 mM 2HPβCD relative to without 2HPβCD. No further improvement was observed with the addition of any of the divalent cations. Dalbavancin in a 1:10 molar ratio with 2HPβCD was more stable at a concentration of 1 mg/mL than at 20 mg/mL under accelerated conditions at 40 °C for six months. ITC revealed two 2HPβCD binding sites to dalbavancin in 10 mM acetate: one with a 1:1 stoichiometry and thermodynamics consistent with known cyclodextrin–drug interactions, and a second with 0.1:1 stoichiometry, a positive binding enthalpy, and an unusually large entropy of binding. NMR spectroscopy indicates that dalbavancin exhibits aggregation in acetate buffer that is disrupted by 2HPβCD binding. Conclusions: 2HPβCD significantly improves the short- and long-term heat stability of dalbavancin in pH 4.5 acetate buffer at and above molar ratios of 1:1. The strong 1:1 binding of 2HPβCD to dalbavancin demonstrated by ITC confirms that this stability is conferred by the formation of a stable complex. This observation, combined with the NMR results, points to the aliphatic hydrocarbon chain of the glycone moiety as the most likely site of 2HPβCD–dalbavancin interaction. [ABSTRACT FROM AUTHOR]

We cross-linked unfractionated heparin (H) using epichlorohydrin (E), in the absence or presence of imidazole (I), using various ratios of H, E, and I substances. The objectives and goals were to use the reaction for the preparation of medical materials suitable for blood sample applications. Nuclear magnetic resonance indicated the involvement of an H-end sequence [H-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl-α-Ser] in the linkage with the 2-hydroxypropyl bridge. The yields of the individual experiments were found to increase in the following ratios: 1H/1E/3I (24%) < 1H/1E/2I (32%) < 1H/3E (42%) < 1H/1E/1I (46%) < 1H/2E (64%) < 1H/1E (77%). According to size-exclusion chromatography with multiple-angle light scattering (SEC-MALS) analysis, the mass at the peak increased in the following order: H (9292 g/mol) < 1H/1E (9294 g/mol) < 1H/2E (9326 g/mol) < 1H/3E (9708 g/mol) < 1H/1E/2I (11,212 g/mol) < 1H/1E/3I (12,301 g/mol) < 1H/1E/1I (13,800 g/mol) and in the reverse order with the increase in amount of epichlorohydrin and imidazole, i.e., 1H/1E > 1H/2E > 1H/3E and 1H/1E/1I > 1H/1E/2I > 1H/1E/3I. X-ray diffraction revealed that all prepared films were amorphous. An evaluation of the surface morphology using atomic force microscopy (AFM) confirmed a relatively low films roughness (~0.9–3.6 nm). The surface reduced elastic modulus, determined by the PeakForce quantitative nanomechanical mapping (PF-QNM) technique, was found to increase by up to ~63% for films cross-linked with E in the absence of I when compared with the results for the H substrate. A negligible change in modulus was, however, observed for films cross-linked in the presence of I, or was even reduced by ~15% (1H/1E/3I) compared to that for the H substrate. This could be explained by the parallel cross-linking of H only with E within its serine end unit and in competition with only one nitrogen of I. According to the highest yield (77%) of 1H/1E, the preferred product is the following: H-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl-α-Ser-CH2-CH(OH)-CH2-OH. For the 1H/1E/1I (46% yield), 1H/1E/2I (32%), and 1H/1E/3I (24%) products, the cross-linked motif was the same, and the difference represented the surplus amount of the imidazolium cation ionically bound to the heparin anionic groups. [ABSTRACT FROM AUTHOR]

In order to investigate the impact of freeze–thaw damage on sandstone under the coupling of ground stress and pore water pressure, three types of porous sandstone were subjected to freezing at different negative temperatures (−5 °C, −10 °C, −15 °C, and −20 °C). Subsequently, hydraulic coupling triaxial compression tests were conducted on the frozen and thawed sandstone. We analyzed the effects of porosity and freezing temperature on the mechanical properties of sandstone under hydraulic coupling and performed nuclear magnetic resonance tests on sandstone samples before and after freezing and thawing. The evolution of the pore structure in sandstone at various freezing and thawing stages was studied, and a statistical damage constitutive model was established to validate the test results. The results indicate that the stress–strain curves of sandstone samples under triaxial compression after a freeze–thaw cycle exhibit minimal changes compared to those without freezing at normal temperature. The peak deviator stress shows a decreasing trend with decreasing freezing temperature, particularly between −5 °C and −10 °C, and then gradually stabilizes. The elastic modulus of sandstone with different porosity decreases with the decrease in freezing temperature, and the decrease is more obvious in the range of −5 °C~−10 °C, decreasing by 2.33%, 6.11%, and 10.5%, respectively. Below −10 °C, the elastic modulus becomes similar to that at −10 °C, and the change tends to stabilize. The nuclear magnetic porosity of sandstone samples significantly increases after freezing and thawing. The smaller the initial porosity, the greater the rate of change in nuclear magnetic porosity after a freeze–thaw cycle. The effects of freeze–thaw damage on the T2 distribution of sandstone with different porosity levels vary. We established a statistical damage constitutive model considering the combined effects of freeze–thaw damage, ground stress, and pore water pressure. The compaction coefficient K was introduced into the constitutive model for optimization. The change trend of the theoretical curve closely aligns with that of the test curve, better characterizing the stress–strain relationship of sandstone under complex pressure environments. The research findings can provide a scientific basis for wellbore wall design and subsequent maintenance in complex environments. [ABSTRACT FROM AUTHOR]

Phosphonates derivatives are compounds of interests and are applied as drugs of, e.g., antibacterial antiviral activities, connected with their inhibitory activity towards different enzymes, which is related to the configuration of particular compound isomers. The biological synthesis of such molecules is the method of choice and can be carried out using enzymes or whole cells from organisms. Photobiocatalysts employed in the bioconversion of epoxymethyl dimethyl phosphonate are able to convert this substrate into a pure geometric isomer of the unsaturated product, dimethyl (1E)-3-hydroxyprop-1-enylphosphonate, which is a rare and expensive compound of high added value. Six different strains were screened towards dimethyl epoxy phosphonate and in the case of Synechococcus bigranulatus, over 99% conversion was achieved. The product structure was confirmed with Mass Spectroscopy (MS); 1H, 13C, 31P, and 2D Nuclear Magnetic Resonance (NMR); and Infrared Spectroscopy (IR). [ABSTRACT FROM AUTHOR]