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Tannin-based foams have gained attention as a potential bio-based alternative to conventional synthetic foams. Traditionally, namely condensed tannins (CT) have been used, leaving the potential of hydrolysable tannins (HT) largely unexplored. This study compared the performance of chestnut (HT) and quebracho (CT) in tannin–protein-based foams at different tannin ratios. Using soy protein isolate (SPI) and hexamine under acidic conditions, a series of tannin foams were produced through a mechanical foaming method and analyzed for cell structure, compression strength, thermal conductivity, and chemical stability. Results show that chestnut tannin is viable in hexamine SPI formulations but is harder to process due to lower reactivity, further resulting in higher material densities compared to quebracho. Foams with higher quebracho content featured smaller, more interconnected cells, while increasing chestnut content led to larger, less interconnected cells. Compression strength decreased with higher chestnut content, while fire resistance and thermal conductivity were influenced by material density rather than tannin type. The 13C-NMR analysis revealed covalent bonding of hexamine with both tannins, but potential covalent bonds with SPI were undetectable. Overall, chestnut tannin can substitute quebracho tannin in hexamine-SPI foams, though with compromises in terms of specific material properties and processability. [ABSTRACT FROM AUTHOR]

ABSTRACT Besides classic illegal drugs, numerous designer drugs, also called new psychoactive substances (NPSs), are available on the global drug market. One of the biggest and fastest‐growing substance classes comprises the synthetic cannabinoids. According to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), 254 out of 950 monitored substances belong to this group of NPS, with 9 new cannabinoids registered for the first time in 2023. For their purchase, it is not necessary to use the dark web. Due to the structural differences compared to the illegal Δ9‐THC (delta‐9‐tetrahydrocannabinol), the legal status changes and the synthetic cannabinoids are available via clear web pages. They come as powders or dissolved and sprayed onto non‐psychoactive layers such as cannabidiol hemp, industrial hemp or also on other plant material like herbal tea mixtures or dried flowers. These adulterated plant parts can be smoked as a substitute to the psychoactive and in many countries illegal Δ9‐THC‐containing hemp. The main task of this project was to check the identity of online available synthetic cannabinoid samples and to generate experimental data using a combination of gas and liquid chromatography with mass spectrometric detection and NMR‐based structure elucidation. In total, 25 substances in solid state were bought from various online shops. They turned out to be 21 synthetic cannabinoids after analysis, including 13 with no or incomplete experimental NMR data available in the literature and one, CH‐PIATA, which has not been mentioned in literature yet. More than 50% of the acquired substances were falsely declared. [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]

ABSTRACT Alpinia zerumbet (Pers.) B.L.Burtt & R.M.Sm, known as shell ginger, is an aromatic plant widely distributed in tropical and subtropical regions. In Guizhou Province of China, its mature fruits have been used by the Miao people for the treatment of cardiovascular diseases. Although the bioactivities of mature fruits of A. zerumbet are derived from phytochemicals in the seeds and pericarps of the plant, there remains a dearth of reports on the isolation of phytochemicals from the pericarp of A. zerumbet. In the present study, the pericarps of mature fruits of A. zerumbet were extracted, and two new kavalactone dimers, alpingsin E (1) and aniba dimer D (2), were isolated. Their structures were determined on the basis of extensive spectroscopic analysis and NMR calculations. Especially, density functional theory–based NMR chemical shift calculations were employed to elucidate and confirm the relative configuration of 1 and 2. [ABSTRACT FROM AUTHOR]

Fine roots are key to ecosystem-scale nutrient, carbon (C), and water cycling, yet our understanding of fine root trait variation within and among tropical forests, one of Earth's most C-rich ecosystems, is limited. We characterized root biomass, morphology, nutrient content, and arbuscular mycorrhizal fungal (AMF) colonization to 1.2 m depths across four distinct lowland Panamanian forests, and related root characteristics to soil C stocks. We hypothesized that: (H1) Fine root characteristics vary consistently with depth across seasonal tropical forests, with deeper roots exhibiting more exploratory traits, such as for deep water acquisition; (H2) fine root characteristics vary among tropical forests mainly in surface soils, where resource availability also varies. We found consistent variation with depth across the four forests, including decreased root biomass, root tissue density, and AMF, and increased specific root length. Among the forests, there was variation in some fine root characteristics, including greater surface root biomass and lower SRL in the wettest forest, and smaller fine root diameter in the driest forest. We also found that root characteristics were related to total soil C stocks, which were positively related to root biomass and negatively related to specific root length. These results indicate emergent properties of root variation with depth across tropical forests, and show site-scale variation in surface root characteristics. Future work could explore the flexibility in root characteristics under changing conditions such as drought. [ABSTRACT FROM AUTHOR]

Leukemia is a group of blood cancers that are classified in four major classes. Within these four classes, many different subtypes exists with similar origin, genetic mutations, and level of maturity, which can make them difficult to distinguish. Despite their similarities, they might respond differently to treatment, and therefore distinguishing between them is of crucial importance. A deranged metabolic phenotype (Warburg effect) is often seen in cancer cells, leukemia cells included, and is increasingly a target for improved diagnosis and treatment. In this study, hyperpolarized 13C NMR spectroscopy was used to characterize the metabolic signatures of the six leukemia cell lines ML‐1, CCRF‐CEM, THP‐1, MOLT‐4, HL‐60, and K562. This was done using [1‐13C]pyruvate and [1‐13C]alanine as bioprobes for downstream metabolite quantification and kinetic analysis on cultured cells with and without 2‐deoxy‐D‐glucose treatment. The metabolic signatures of similar leukemia subtypes could be readily distinguished. This includes ML‐1 and THP‐1, which are of the similar M4 and M5 AML subtypes, CCRF‐CEM and MOLT‐4, which are of the similar T‐ALL lineage at different maturation states, and HL‐60 and K562, which are of the closely related M1 and M2 AML subtypes. The data presented here demonstrate the potential of hyperpolarized 13C NMR spectroscopy as a method to differentiate between leukemia subtypes of similar origin. Combining this method with bioreactor setups could potentially allow for better leukemia disease management as metabolic signatures could be acquired from a single biopsy through repeated experimentation and intervention. [ABSTRACT FROM AUTHOR]

[Purposes] While extensive research has been conducted on the evolution of coal′s molecular structure during coalification, the heterogeneity and complexity of coal continue to impede the accurate and precise quantitative characterization of its structural evolution mechanism. [Methods] Through maceral identification, vitrinite reflectance, industrial quality, elemental analysis, and spectral analysis, the carbon skeleton structure and occurrence state of functional groups of bituminous coal (FS1) and anthracite coal (ZY1) were determined. Two molecular structure models were established by computer-aided molecular design. [Finding] The results show that with the progress of coalification, the loss rate of methylene is faster than that of methyl in the process of bituminous coal to anthracite, the aromaticity is enhanced, the aliphatic chain of aromatic ring becomes shorter and the degree of branching is higher, the oxygen-containing functional groups is gradually reduced, the crystallinity of coal is enhanced, and the chemical structure of coal tends to be mature and stable. At the sometime, the content of aliphatic carbon in coal decreases, the content of aromatic carbon increases, and the content of methyl carbon and methylene carbon decreases. After several attempts, the bonding mode between aromatic carbon, aliphatic side chain, and oxygen functional group was determined, and the final molecular structure models were obtained: C175H162O13N2 (FS1), C190H159O5N3 (ZY1). These models well reflect the real structure of coal, and the simulated 13C NMR spectra are in good agreement with the experimental spectra. The above research provides a theoretical reference for the molecular structure evolution of coal with different metamorphic degrees, and provides a method for establishing high-reliability molecular structure characterization.

ABSTRACT One new monacolin analog, monacolin V (1), together with two new monacolin‐like natural products, 6‐hydroxyl monacolin P (2) and 3‐keto monacolin S (3), were isolated from the ethyl acetate portion of red yeast rice ethanol extract. Their structures were identified by HRESIMS and NMR experiments, and the complete assignments of 1H and 13C NMR data for three compounds were obtained by the aid of HSQC, HMBC, 1H‐1H COSY, and NOESY data. This is the first time that the NMR data of compounds 2 and 3 have been fully assigned. [ABSTRACT FROM AUTHOR]

A root factor for the accuracy of all quantum chemical calculations of nuclear magnetic resonance (NMR) chemical shifts is the quality of the molecular equilibrium geometry used. In turn, this quality depends largely on the basis set employed at the geometry optimization stage. This parameter represents the main subject of the present study, which is a continuation of our recent work, where new pecG-n (n = 1, 2) basis sets for the geometry optimization were introduced. A goal of this study was to compare the performance of our geometry-oriented pecG-n (n = 1, 2) basis sets against the other basis sets in massive calculations of 13C NMR shielding constants/chemical shifts in terms of their efficacy in reducing geometry factor errors. The testing was carried out with both large-sized biologically active natural products and medium-sized compounds with complicated electronic structures. The former were treated using the computation protocol based on the density functional theory (DFT) and considered in the theoretical benchmarking, while the latter were treated using the computational scheme based on the upper-hierarchy coupled cluster (CC) methods and were used in the practical benchmarking involving the comparison with experimental NMR data. Both the theoretical and practical analyses showed that the pecG-1 and pecG-2 basis sets resulted in substantially reduced geometry factor errors in the calculated 13C NMR chemical shifts/shielding constants compared to their commensurate analogs, with the pecG-2 basis set being the best of all the considered basis sets. [ABSTRACT FROM AUTHOR]

The control of metabolic networks is incompletely understood, even for glycolysis in highly studied model organisms. Direct real-time observations of metabolic pathways can be achieved in cellular systems with 13C NMR using dissolution Dynamic Nuclear Polarization (dDNP NMR). The method relies on a short-lived boost of NMR sensitivity using a redistribution of nuclear spin states to increase the alignment of the magnetic moments by more than four orders of magnitude. This temporary boost in sensitivity allows detection of metabolism with sub-second time resolution. Here, we hypothesized that dDNP NMR would be able to investigate molecular phenotypes that are not easily accessible with more conventional methods. The use of dDNP NMR allows real-time insight into carbohydrate metabolism in a Gram-positive bacterium (Lactoccocus lactis), and comparison to other bacterial, yeast and mammalian cells shows differences in the kinetic barriers of glycolysis across the kingdoms of life. Nevertheless, the accumulation of non-toxic precursors for biomass at kinetic barriers is found to be shared across the kingdoms of life. We further find that the visualization of glycolysis using dDNP NMR reveals kinetic characteristics in transgenic strains that are not evident when monitoring the overall glycolytic rate only. Finally, dDNP NMR reveals that resting Lactococcus lactis cells use the influx of carbohydrate substrate to produce acetoin rather than lactate during the start of glycolysis. This metabolic regime can be emulated using suitably designed substrate mixtures to enhance the formation of the C4 product acetoin more than 400-fold. Overall, we find that dDNP NMR provides analytical capabilities that may help to clarify the intertwined mechanistic determinants of metabolism and the optimal usage of biotechnologically important bacteria. [ABSTRACT FROM AUTHOR]

The characteristics of biochar vary widely depending on the type of biomass and thermochemical conversion method. In this study, four types of biomass (kenaf, rice husk, corncob, and wood chips) were subjected to hydrothermal carbonization and torrefaction at 220 °C, 260 °C, and 300 °C for 30 min. The acquired biochars showed significant differences in the type of reaction and biomass. At each temperature, the decomposition of volatiles was more severe in hydrochar (HC) than in torrefied char (TC). The mass yields of HC were 44.30–61.63 wt.% (220 °C), 20.89–37.04 wt.% (260 °C), and 12.59–29.19 wt.% (300 °C), whereas the mass yields of TC were 94.73–97.69 wt.% (220 °C), 87.19–95.04 wt.% (260 °C), and 68.22–80.78 wt.% (300 °C). The elemental and thermal characteristics of TC changed gradually as the reaction temperature increased, and the characteristics of HC were enhanced rapidly. Wood chip biochar that was reacted at 300 °C showed the highest heating values of 28.77 MJ/kg (HC) and 21.09 MJ/kg (TC). The results of chemical analyses showed that hydrothermal carbonization strongly affected the cleavage of inter- and intra-molecular carbon bonds in cellulose and hemicellulose. In contrast, torrefaction removed the thermally fragile moisture and hemicellulose content from biomass. [ABSTRACT FROM AUTHOR]

New probe naphthalen-2-yl-N′-(2-hydroxybenzoyl)benzohydrazonate (NHBH) chemosensor has been prepared and characterized by IR, 1H NMR, 13C NMR and Mass Spectroscopic techniques. The probe (NHBH) was subjected to study its cation sensing ability with twelve different metal chloride salt (Al3+, Ca2+, Co2+, Cr3+, Fe3+, Cu2+, Mn2+, Ni2+, Zn2+, Hg2+, K+ and Na+) in 1:4 methanol water medium by using absorption and emission titration experiments. The results showed that the probe detected Fe3+ and Na ​+ ​ions by showing absorption enhancement and fluorescence emission quenching. Further, NHBH exhibited good selectivity for Fe3+ and Na ​+ ​ions in the presence of mostother metal ions. Job's plot analysis authenticated the 1:1 binding nature of NHBH with Fe3+ and Na ​+ ​ions. Further, DFT studies validated the formation of probe (NHBH), fluorophore-quencher (Fe-NHBH) complex formation.

Isatin-derived Schiff bases are the subject of many studies, finding wide application areas in polymer technology, pharmaceutical industry, and medicine. In this study, a series of new Schiff bases were prepared from monothiocarbohydrazones based on isatins with different substituents (5-F, 5-Br, 5-I, and 5-MeO). The chemical structures of the synthesized compounds were determined using 1H NMR, 13C NMR, FTIR spectroscopic techniques, and elemental analysis. Antioxidant activity determinations of 23 compounds were performed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical quenching method. The highest percent inhibition value at 10 µM concentration was shown by compound number 22, 5-bromoisatin Schiff base containing 3-methoxy-4-hydroxy group. Compound 17, a 5-iodoisatin Schiff base containing 3-methoxy-4-hydroxy group, showed the highest antioxidant activity with an IC50 value of 9.76 ± 0.03 µM. In addition to the theoretical analysis of the compounds, both their spectroscopic and antioxidant properties were investigated. The ground-state geometries and some chemical reactivity parameters of the compounds were calculated using the B3LYP/6-311 + + G(2d,2p) approach. Besides intramolecular interactions, substituent effects, and some QTAIM parameters, the calculations were also performed to study the electronic properties of reactive N/O–H bonds and were used to interpret the experimental results. The effects of the electronic parameters and intramolecular interactions of reactive N/O–H bonds on the antioxidant properties of the compounds were investigated. Additionally, the relationships of DPPH reactions with delocalization indices of N/O-H bonds and the pattern of SET/HAT mechanisms with electronic variables were analyzed. Examination of electron and hydrogen atom transfer mechanisms has shown the dominance of electron transfer, supported by the correlation coefficients between IC50 values and SET reaction energies. [ABSTRACT FROM AUTHOR]

The bio-depolymerization of coal is a promising technology for converting coal into low-molecular-weight industrial chemicals. In this study, we investigated the characteristics of biodepolymerized coal (BDC) and the associated depolymerization pathway. We analyzed the extracellular enzyme activities of Hypocrea lixii AH in the biodepolymerization system, performed Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance spectroscopy (NMR) of BDC, and performed gas chromatography and mass spectrometry (GC/MS) of the BDC methanol extract. Results showed that the activities of peroxidase (POD), polyphenol oxidase (PPO), laccase (Lac), and lignin peroxidase (LiP) were 1377, 162, 10, and 1.919 U, respectively. Following biodepolymerization by Hypocrea lixii AH, 20 organic compounds were identified. Benzaldehyde 4-hydroxy-3,5-dimethoxy was the most dominant at 33.16%, followed by (Z)-9-octadecenamide, accounting for 14.73%. The aromaticity (fa) decreased from 54.3% to 23.7%, suggesting ring-opening reactions catalyzed by LiP and Lac. The ratio of carbonyl carbon (faC) increased from 8.3% to 16.2%, suggesting oxidation reactions catalyzed by POD. By comparing the structure of the Fushun oxidized coal model and BDC, a biodepolymerization pathway was elucidated. Biodepolymerization of Fushun oxidized coal is an oxidation–depolymerization process catalyzed by a series of enzymes, which breaks the aromatic rings and oxidizes side chains. Altogether, our findings provide a theoretical support for the chemical application of BDC. [ABSTRACT FROM AUTHOR]

Early NMR studies of several heterohelicenes containing an annular nitrogen atom and a thiophene ring in their structure suggested the possibility of the lengthening of the carbon–carbon bonds in the interior of the helical turn of the molecule based on the progressive upfield shift of 13C resonances toward the center of the helical turn. We now report a comprehensive analysis of the optimized geometry and a comparison of the calculated vs. observed 1H and 13C NMR chemical shifts of nineteen representative benzothienoquinoline heterohelicenes. As was initially hypothesized on the basis of the progressive upfield shift of carbon resonances toward the center of the interior helical turn, the present computational study has demonstrated that carbon–carbon bonds indeed have more sp3 character and are longer than normal sp2 bonds to accommodate the helical twist of the molecule, as expected. [ABSTRACT FROM AUTHOR]

Mefloquine (MQ) is an antimalarial medication prescribed to treat or malaria prevention.. When taken by children, vomiting usually occurs, and new doses of medication frequently need to be taken. So, developing pediatric medicines using taste-masked antimalarial drug complexes is mandatory for the success of mefloquine administration. The hypothesis that binding mefloquine to an ion-exchange resin (R) could circumvent the drug's bitter taste problem was proposed, and solid-state 13C cross-polarization magic angle spinning (CPMAS) NMR was able to follow MQ–R mixtures through chemical shift and relaxation measurements. The nature of MQ–R complex formation could then be determined. Impedimetric electronic tongue equipment also verified the resinate taste-masking efficiency in vitro. Variations in chemical shifts and structure dynamics measured by proton relaxation properties (e.g., T1ρH) were used as probes to follow the extension of mixing and specific interactions that would be present in MQ–R. A significant decrease in T1ρH values was observed for MQ carbons in MQ–R complexes, compared to the ones in MQ (from 100–200 ms in MQ to 20–50 ms in an MQ–R complex). The results evidenced that the cationic resin interacts strongly with mefloquine molecules in the formulation of a 1:1 ratio complex. Thus, 13C CPMAS NMR allowed the confirmation of the presence of a binding between mefloquine and polacrilin in the MQ–R formulation studied. [ABSTRACT FROM AUTHOR]

Four eight‐coordinated luminescent samarium complexes of type [Sm(hfpd)3L2] and [Sm(hfpd)3L′] [where hfpd = 1,1,1,5,5,5‐Hexafluoro‐2,4‐pentanedione L = tri‐octyl‐phosphine oxide (TOPO) and L′ = 1,10‐phenanthroline (phen), neocuproine (neoc) and bathocuproine (bathoc) were synthesized via a stoichiometrically controlled approach. This allows for precise control over the stoichiometry of the complexes, leading to reproducible properties. This investigation focuses on understanding the impact of secondary ligands on the luminescent properties of these complexes. Infrared (IR) spectra provided information about the molecular structures, whereas 1H and 13C nuclear magnetic resonance (NMR) spectra confirmed these structural details along with the coordination of ligands to trivalent Sm ion. The UV–vis spectra revealed the molar absorption coefficient and absorption bands associated with the hfpd ligand and photoluminescence (PL) spectroscopy demonstrated intense orange‐red emission (648 nm relative to 4G5/2 → 6H9/2) from the complexes. The Commission Internationale de l'Éclairage (CIE) triangles indicated that the complexes emitted warm orange red light with color coordinates (x, y) ranging from (0.62, 0.36) to (0.40, 0.27). The investigation of the band gap as well as color parameters confirms the utility of these complexes in displays and LEDs. [ABSTRACT FROM AUTHOR]

Cover crops are one of the climate-smart agricultural practices used to increase soil organic carbon (SOC) sequestration. However, the SOC sequestration potential and underlying mechanisms under different cover crops, especially in orchard agroecosystems, have not been fully elucidated. Here, we investigated three orchards in China using SOC fractionation methods, high-throughput sequencing, and biomarker analysis. Our objectives were to determine the effect of cover crops on the physical fractions and chemical compositions of SOC, as well as on microbial properties, and to clarify why legume and non-legume cover crops sequester SOC differently. The results showed different increases in SOC between legume and non-legume cover crops (+38% vs. +16%) compared with those in the control plots without cover crops. Legume cover crops increased mineral-associated and particulate organic carbon, whereas non-legume cover crops increased mineral-associated organic carbon only. These differences were attributed to their distinct effects on microbial SOC transformation pathways. Legume cover crops positively impacted microbial pathways by increasing the availability of soil substrates and nitrogen, such as dissolved organic carbon (+84%), O-alkyl carbon (+18%), and ammonium nitrogen (+42%). These results were supported by the increases in carbon and nitrogen enzyme activities, microbial community diversity indices, the abundance of dominant fungal taxa (Sordariomycetes), microbial biomass carbon (+105%), and microbial necromass carbon (+47%). Non-legume cover crops might have induced microbial nitrogen starvation, decreasing the efficiency of microbial pathways, as evidenced by the low β-glucosidase to β-N-acetylglucosaminidase ratios (−7%) and the lack of significant changes in the bacterial Shannon index or microbial necromass carbon. In addition, redundancy analysis revealed that enzyme activity, the microbial community, and microbial necromass carbon collectively dominated the changes in the SOC physical fraction. Site-specific soil properties such as soil texture and nitrogen availability were important factors influencing SOC sequestration under cover crops. Our study provides essential insights for optimizing cover crop management to increase SOC sequestration in orchard agroecosystems.

While spent mushroom substrate (SMS) has shown promise in increasing soil organic carbon (SOC) and improving soil quality, research on the interplay between SOC components and microbial community following the application of diverse SMS types remains scant. A laboratory soil incubation experiment was conducted with application of two types of SMSs from cultivation of Pleurotus eryngii (PE) and Agaricus bisporus (AB), each at three application rates (3, 5.5, and 8%). Advanced techniques, including solid-state 13C nuclear magnetic resonance (NMR) and high-throughput sequencing, were employed to investigate on SOC fractions and chemical structure, microbial community composition and functionality. Compared to SMS-AB, SMS-PE application increased the relative abundances of carbohydrate carbon and O-alkyl C in SOC. In addition, SMS-PE application increased the relative abundance of the bacterial phylum Proteobacteria and those of the fungal phyla Basidiomycota and Ascomycota. The relative abundances of cellulose-degrading bacterial (e.g., Flavisolibacter and Agromyces) and fungal genera (e.g., Myceliophthora, Thermomyces, and Conocybe) were increased as well. The application of SMS-AB increased the aromaticity index of SOC, the relative abundance of aromatic C, and the contents of humic acid and heavy fraction organic carbon. In addition, SMSAB application significantly increased the relative abundances of the bacterial phyla Firmicutes and Actinobacteria. Notably, the genera Actinomadura, Ilumatobacter, and Bacillus, which were positively correlated with humic acid, experienced an increase in relative abundance. Functional prediction revealed that SMS-PE application elevated carbohydrate metabolism and reduced the prevalence of fungal pathogens, particularly Fusarium. The application of highrate SMS-AB (8%) enhanced bacterial amino acid metabolism and the relative abundances of plant pathogenic fungi. Our research provides strategies for utilizing SMS to enrich soil organic carbon and fortify soil health, facilitating the achievement of sustainable soil management. [ABSTRACT FROM AUTHOR]

Chitin, a ubiquitous biopolymer, holds paramount scientific and economic significance. Historically, it has been primarily isolated from marine crustaceans. However, the surge in demand for chitin and the burgeoning interest in biopolymers have necessitated the exploration of alternative sources. Among these methods, the mulberry silkworm (Bombyx mori) has emerged as a particularly intriguing prospect. To isolate chitin from Bombyx mori, a chemical extraction methodology was employed. This process involved a series of meticulously orchestrated steps, including Folch extraction, demineralization, deproteinization, and decolorization. The resultant chitin was subjected to comprehensive analysis utilizing techniques such as attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), 13C nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray scattering (WAXS). The obtained results allow us to conclude that the Bombyx mori represents an attractive alternative source of α-chitin. [ABSTRACT FROM AUTHOR]

Chicken feathers represent a viable material for producing biochar adsorbents. Traditional slow pyrolysis methods often result in sulfur element losses from chicken feathers, whereas hydrothermal reactions generate substantial amounts of nutrient-rich hydrothermal liquor. Magnesium-modified high-sulfur hydrochar MWF was synthesized through magnesium modification, achieving a S content of 3.68%. The maximum equilibrium adsorption amounts of MWF for Cd2+ and Pb2+ were 25.12 mg·g−1 and 70.41 mg·g−1, respectively, representing 4.00 times and 2.75 times of WF. Magnesium modification elevated the sulfur content, pH, ash content, and electronegativity of MWF. The primary mechanisms behind MWF's adsorption of Cd2+ and Pb2+ involve magnesium ion exchange and complexation with C=O/O=C–O, quaternary N, and S functional groups. MWF maintains robust stability and antioxidative properties, even with low aromaticity levels. Given the lower energy consumption during hydrochar production, MWF offers notable carbon sequestration benefits. The hydrothermal solution derived from MWF is nutrient-rich. Following supplementation with inorganic fertilizer, the hydrothermal solution of MWF significantly enhanced bok choy growth compared to the control group. In general, adopting magnesium-modified hydrothermal reactions to produce hydrochar and converting the resultant hydrothermal solution into water-soluble fertilizer proves a viable strategy for the eco-friendly utilization of chicken feathers. This approach carries substantial value for heavy metal remediation and agricultural practices. [ABSTRACT FROM AUTHOR]

Since the discovery of the first ferroelectric liquid crystal (FLC) in the chiral smectic C (SmC*) phase, ferroelectricity in liquid crystals has attracted much attention due to not only the fundamental interest but also the applications. This review focuses on the evolution of the design concept for ferroelectric smectic liquid crystals. It progresses from considering macroscopic phase symmetry to designing intermolecular interactions. For the purpose of understanding the molecular organization in smectic phases, we propose a dynamic model of constituent molecules in the smectic A (SmA) and SmC* phases based on 13C NMR studies. Then, we follow the structure–property relationship in ferroelectric SmC* liquid crystals for FLC displays. We reconsider de Vries-like materials that can provide defect-free alignment. We pay attention to the electro-optical switching in the chiral de Vries smectic A phase. Finally, we show several liquid crystals exhibiting polar smectic A phases and discuss how the polar order occurs in the highest symmetric smectic A phase. [ABSTRACT FROM AUTHOR]

Nickel complexes with a two‐electron reduced CO2 ligand (CO22−, "carbonite") are investigated with regard to the influence alkali metal (AM) ions have as Lewis acids on the activation of the CO2 entity. For this purpose complexes with NiII(CO2)AM (AM=Li, Na, K) moieties were accessed via deprotonation of nickel‐formate compounds with (AM)N(iPr)2. It was found that not only the nature of the AM ions in vicinity to CO2 affect the activation, but also the number and the ligation of a given AM. To this end the effects of added (AM)N(R)2, THF, open and closed polyethers as well as cryptands were systematically studied. In 14 cases the products were characterized by X‐ray diffraction and correlations with the situation in solution were made. The more the AM ions get detached from the carbonite ligand, the lower is the degree of aggregation. At the same time the extent of CO2 activation is decreased as indicated by the structural and spectroscopic analysis and reactivity studies. Accompanying DFT studies showed that the coordinating AM Lewis acidic fragment withdraws only a small amount of charge from the carbonite moiety, but it also affects the internal charge equilibration between the LtBuNi and carbonite moieties. [ABSTRACT FROM AUTHOR]

The object of the study is lignite. Analytical testing techniques, such as elemental analysis, 13C nuclear magnetic resonance (13C NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM), were used to acquire information on the structural parameters of lignite. The aromaticity of Xianfeng lignite is 43.57%, and the aromatic carbon structure is mainly naphthalene and anthracene/phenanthrene. The aliphatic carbon structure is dominated by cycloalkanes, alkyl side chains, and hydrogenated aromatics. Oxygen is mainly present in ether oxygen, carboxyl, and carbonyl groups. Nitrogen is mainly in the form of pyrrole nitrogen and quaternary nitrogen. Sulfur is mainly thiophene sulfur. According to the analysis results, the molecular structure model of XF lignite was constructed. The molecular formula is C184H172O39N6S2. The 2D structure was converted to a 3D structure using computer simulation software and optimized. The optimized model has a remarkable stereoconfiguration, and the aromatic lamellae are irregularly arranged in space. The aromatic rings were mainly connected by methylene, hypomethylene, methoxy, and aliphatic rings. In addition, the simulated 13C NMR spectra are in good agreement with the experimental spectra. This shows the rationality of the 3D chemical structure model. [ABSTRACT FROM AUTHOR]

Extracts of plant origin, particularly tannins, are attracting growing interest for the sustainable development of materials in the industrial sector. The discovery of new tannins is therefore necessary. The aim of this work was to contribute to the understanding of the properties of Paraberlinia bifoliolata tannin by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy MALDI-TOF/MS and Carbon 13 Nuclear Magnetic Resonance (13C NMR). The chemical composition of tannin extracted from Paraberlinia bifoliolata bark was determined, as was the mechanical strength of the resin hardened with Acacia nilotica extracts. Yield by successive water extraction was 35%. MALDI-TOF/MS analysis revealed the presence of three new compounds in this tannin, previously unknown in this family of extracts. These are 3-hydroxyproline acid, N-methyl-4-hydroxypipecolic acid and N-methyl-5-dihydroxypipecolic acid. The identification of the above molecules means that this tannin can be used for industrial applications, as a resin in the manufacture of particleboard and in the formulation of green corrosion inhibitors. This information is reinforced by 13C NMR spectrometry, which indicates the presence of several polyflavonoid units, confirming the condensed nature of the tannin. Thermomechanical analysis of the resin formed by the purified tannin of Paraberlinia bifoliolata to which a vegetal biohardener has been added provided a Modulus of Elasticity (MOE) value of 4840 MPa at 150°C, confirming its possible use as a binder resin in the manufacture of wood panels as well as for the formulation of a corrosion inhibitor. [ABSTRACT FROM AUTHOR]

13C NMR spectroscopic analyses of Cs symmetric guest molecules in the cyclodextrin host cavity, combined with molecular modelling and solid-state X-ray analysis, provides a detailed description of the spatial arrangement of cyclodextrin host–guest complexes in solution. The chiral cavity of the cyclodextrin molecule creates an anisotropic environment for the guest molecule resulting in a splitting of its prochiral carbon signals in 13C NMR spectra. This signal split can be correlated to the distance of the guest atoms from the wall of the host cavity and to the spatial separation of binding sites preferred by pairs of prochiral carbon atoms. These measurements complement traditional solid-state analyses, which rely on the crystallization of host–guest complexes and their crystallographic analysis.

Quantitative NMR experiments are an essential part of NMR analysis, which play a critical role in component analysis and compound structure identification. Carbon atoms form the framework of organic compounds, and 13C NMR has unique advantages in organic analysis due to its wide chemical shift range, narrow spectral peaks, and broadband decoupling capability. However, the low natural abundance, low gyromagnetic ratio, and long longitudinal relaxation time of 13C nuclei hinder its wider application in quantitative experiments. In our previous work, we proposed the Q-DEPT+ pulse sequence and designed a double loop of pulse flip angle and polarization transfer time, which allows for uniform sensitivity enhancement for the three types of carbon nuclei, CH, CH2, and CH3, within a wide 1JCH range, making it suitable for quantitative 13C NMR. In this study, we further optimized the polarization transfer time and read pulse width of the Q-DEPT+ experiment by using a genetic algorithm, and replaced the 180° hard pulse in the 13C channel with a G5 composite pulse that compensates for the frequency offset effect. The optimized pulse sequence was named Q-DEPT ++. Quantitative experiments were performed on cholesterol acetate in CDCl3 by using the reverse-gated decoupling pulse sequence (zgig), Q-DEPT+, and Q-DEPT++ respectively, and the quantification accuracy and sensitivity of the three pulse sequences were compared. The results showed that Q-DEPT++ has obvious improvement in both quantification accuracy and sensitivity.

Scientific relevance. Hypromellose phthalate is a component of enteric coatings used to modify active substance release from oral medicinal products in the small intestine. The release rate directly depends on the non-stoichiometric composition of the polymer, first of all, on the proportion of phthalate groups in the macromolecule. It is therefore necessary to develop reliable analytical procedures for determining the structure of hypromellose phthalate to evaluate the dissolution rate of medicinal products containing the polymer.Aim. The study aimed to develop an analytical procedure for quantifying the proportion of phthalate groups in hypromellose phthalate samples using NMR spectroscopy and to determine the relationship between the polymer dissolution rate in aqueous buffer solutions and its structural features (degree of molar substitution and molecular mass).Materials and methods. The study examined hypromellose phthalate samples isolated from enteric coatings of proton-pump inhibitors and used the reference standard for hypromellose phthalate. The non-stoichiometric composition of the polymer was determined by 13C NMR spectroscopy.Results. The authors established the conditions required to separate hypromellose phthalate from the other coating components and identified the characteristic 13C NMR signals that may be used to differentiate between the structural fragments of hypromellose phthalate. The study demonstrated the relationship between the dissolution rate and the structure of the polymer. Commercial grades of hypromellose phthalate were shown to differ in composition and, as a result, in their dissolution kinetics (in particular, the threshold pH for the onset of dissolution (5.0–5.5), as well as the dissolution rates at the same pH).Conclusions. The authors developed NMR-based procedures to determine the proportion of phthalate groups on the basis of their mass fraction in a weighted hypromellose phthalate sample and the degree of molar substitution of the polymer. The results support the applicability of these analytical procedures to the characterisation of sample composition in polymer dissolution rate studies. In principle, it is possible to derive a multiple linear regression equation that describes the dissolution rate of hypromellose phthalate as a function of the molecular mass and the molar substitution with phthalate groups. Further investigation of a larger number of polymer samples with different compositions is needed to improve the regression model and demonstrate its statistical significance. In addition to the proportion of phthalate groups, the pharmacopoeial analysis of hypromellose phthalate should also control the molecular mass of the polymer.

NMR spectroscopy has become a standard technique in studies both on carbon capture and storage. 13C NMR allows the detection of two peaks for carbonated aqueous samples: one for CO2(aq) and another one for the species H2CO3, HCO3−, and CO32−—herein collectively named HxCO3x‐2. The chemical shift of this second peak depends on the molar fraction of the three species in equilibrium and has been used to assess the equilibrium between HCO3− and CO32−. The detection of H2CO3 at low pH solutions is hindered, because of the concurrent liberation of CO2 when the medium is acidified. Herein, a valved NMR tube facilitates the detection of the HxCO3x‐2 peak across a wide pH range, even at pH 1.8 where the dominant species is H2CO3. The method employed the formation of frozen layers of NaH13CO3 and acid solutions within the tube, which are mixed as the tube reaches room temperature. At this point, the tube is already securely sealed, preventing any loss of CO2 to the atmosphere. A spectrophotometry approach allowed the measurement of the actual pH inside the pressurized NMR tube. The chemical shift for H2CO3 was determined as 160.33 ± 0.03 ppm, which is in good agreement with value obtained by DFT calculations combined with Car–Parrinello molecular dynamics. The H2CO3 pKa value determined by the present method was 3.41 ± 0.03, for 15% D2O aqueous medium and 0.8 mol/L ionic strength. The proposed method can be extended to studies about analogs such as alkyl carbonic and carbamic acids. [ABSTRACT FROM AUTHOR]

The robustness of NMR coherence transfer in proximity of a paramagnetic center depends on the relaxation properties of the nuclei involved. In the case of Iron-Sulfur Proteins, different pulse schemes or different parameter sets often provide complementary results. Tailored versions of HCACO and CACO experiments significantly increase the number of observed Cα/C' connectivities in highly paramagnetic systems, by recovering many resonances that were lost due to paramagnetic relaxation. Optimized 13C direct detected experiments can significantly extend the available assignments, improving the overall knowledge of these systems. The different relaxation properties of Cα and C' nuclei are exploited in CACO vs COCA experiments and the complementarity of the two experiments is used to obtain structural information. The two [Fe2S2]+ clusters containing NEET protein CISD3 and the one [Fe4S4]2+ cluster containing HiPIP protein PioC have been taken as model systems. We show that tailored experiments contribute to decrease the blind sphere around the cluster, to extend resonance assignment of cluster bound cysteine residues and to retrieve details on the topology of the iron-bound ligand residues. [ABSTRACT FROM AUTHOR]

There were some ecological and environmental problems in limestone soil in the karst peak-cluster depression in Pingguo City of Guangxi, such as the destruction of soil structure, soil acidification and soil fertility decline, and these problems were closely related to soil organic matter. The soil in this site was classified as Cambisols. Therefore, this project took soil under five major land uses (grassland, afforestation, sugarcane field, corn field and pitaya field) in the karst area of Guangxi as the research object. The contents and molecular structure properties of humic acids, fulvic acids and humins in soils were studied by solid-state 13C nuclear magnetic resonance spectroscopy and elemental composition. From the perspective of the chemical structure of humic substances, the differences in the quantity and structural characteristics of humic acids, fulvic acids and humins in different land uses were revealed. The results showed that the organic carbon content of both afforestation (34.83 g kg−1) and natural restored grassland (31.67 g kg−1) were significantly higher than that of sugarcane field (17.60 g kg−1), corn field (16.35 g kg−1) and pitaya field (14.31 g kg−1) (p < 0.05). The contents of three humic fractions in grassland were relatively high, and the contents of three humic fractions in sugarcane field were relatively low (p < 0.05). The structural characteristics of humic substances showed that the protein components of the three humic fractions in the afforestation were high, indicating that the humic substances in the afforestation contained more unstable components. The Alkyl C/O-alkyl C and Hydrophobic C/hydrophilic C ratios of the three humic fractions of corn field were high, indicating high stability and maturity in humic substances in corn field. [ABSTRACT FROM AUTHOR]

Aminated tannins were prepared by reacting mimosa condensed tannin extract with ammonia yielding the substitution of many, if not all of the tannin hydroxyl groups with -NH2 groups. A tannin-aminated tannin (ATT) particleboard coating was then prepared by reacting raw tannin extract with aminated tannin extract and thus cross-linking the two by substituting tannin's hydroxyl groups with the -NH2 groups on the aminated tannin to form -NH-bridges between the two. The resulting particleboard coating gave encouraging results when pressed at 180°C for 3 min. Conversely, the system in which tannin was reacted/cross-liked with urea (ATU) by a similar amination reaction did not perform as well as the ATT system, and this even when a higher curing temperature and longer hot press time were used. In particular its water repellence was worse probably due to the presence of urea and such a system with lower reactivity. Nonetheless, substituting the tannin -OHs with the urea -NH2 groups appeared to also take place. ATT gave better results than ATU as regards water repellence and mechanical resistance as shown by the cross cut test. The ATT system was shown to be between 95% and 98% biosourced. The difference appeared to be due, by TMA analysis, to the much faster formation of the ATT hardened network leading to a better cross-linked polymer coating. The chemical species formed for both the ATT and ATU system were studied by MALDI ToF and CP MAS 13C NMR. [ABSTRACT FROM AUTHOR]

Abstract In the nuclear magnetic resonance (NMR) test of coal, when the spinning frequency of magic‐angle spinning (MAS) is less than the frequency range of chemical shift anisotropy, serious aromatic carbon spinning sidebands will appear. Existing solutions to the sideband effect, such as changing the MAS frequency, inserting total suppression of sidebands (TOSS) pulse sequences, or simply defining the peak after chemical shift of 200 ppm as the sideband peaks generated by aromatic carbon peak, multipling the identified sideband integral by 2 and adding to the main peaks of protonated aromatic carbon and aromatic bridgehead carbon. None of these methods can reasonably correct for the sideband effect and cause errors to accurately quantifying the carbon structure parameters. Compared with 13C nuclear magnetic resonance (13C NMR) spectrum without sideband suppression (13C CP‐MAS NMR) and 13C NMR spectrum under sideband suppression conditions (13C CP‐MAS/TOSS NMR), according to the chemical shifts of the main peaks of four aromatic carbons, namely protonated aromatic carbon, aromatic bridgehead carbon, alkylated aromatic carbon and oxygen‐linked aromatic carbon, combined with the MAS frequency, the first‐ and second‐level sideband peaks generated by four types of aromatic carbons were accurately located and quantified, and they were added to the corresponding aromatic carbon main peaks in 13C CP‐MAS/TOSS NMR spectrum, thus realizing the accurate correction of sideband effect of the solid‐state 13C NMR spectrum of coal samples. The relative area of corrected aliphatic carbon, carbonyl (carboxyl) carbon, and various aromatic carbons were recalculated, and more accurate carbon structure parameters were obtained, which is significant for studying the coal structure from a microscopic perspective.

Plant‐ and microbially derived carbon (C) are the two major sources of soil organic matter (SOM), and their ratio impacts SOM composition, accumulation, stability, and turnover. The contributions of and the key factors defining the plant and microbial C in SOM along the soil profile are not well known. By leveraging nuclear magnetic resonance spectroscopy and biomarker analysis, we analyzed the plant and microbial C in three soil types using regional‐scale sampling and combined these results with a meta‐analysis. Topsoil (0–40 cm) was rich in carbohydrates and lignin (38%–50%), whereas subsoil (40–100 cm) contained more proteins and lipids (26%–60%). The proportion of plant C increases, while microbial C decreases with SOM content. The decrease rate of the ratio of the microbially derived C to plant‐derived C (CM:P) with SOM content was 23%–30% faster in the topsoil than in the subsoil in the regional study and meta‐analysis. The topsoil had high potential to stabilize plant‐derived C through intensive microbial transformations and microbial necromass formation. Plant C input and mean annual soil temperature were the main factors defining CM:P in topsoil, whereas the fungi‐to‐bacteria ratio and clay content were the main factors influencing subsoil CM:P. Combining a regional study and meta‐analysis, we highlighted the contribution of plant litter to microbial necromass to organic matter up to 1‐m soil depth and elucidated the main factors regulating their long‐term preservation. [ABSTRACT FROM AUTHOR]

Cesium lead bromide perovskite (CsPbBr3) nanocrystals have raised impressive interest as efficient and stable optoelectronic materials. Size and morphology play important roles in the final performances of these materials and advanced characterization studies are needed to elucidate structural and surface properties. In this work, CsPbBr3 cubic nanocrystals were obtained by colloidal synthesis and characterized by multinuclear Solid State NMR (SSNMR), complemented by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and optical spectroscopy. The multinuclear NMR approach allowed the different components of the nanocubes to be separately observed. In particular, the surface ligands and their interactions with the nanocubes surface were investigated by 1H and 13C NMR experiments, while the structural investigation of the perovskite nanocubes was addressed by exploiting 207Pb and 133Cs spectral properties in comparison with bulk CsPbBr3. Static 207Pb NMR spectra indicated a possible contribution of chemical shift anisotropy from the 207Pb nuclei of the outer layer. The 133Cs NMR spectra showed signals with different chemical shifts for cesium atoms in at least three regions of the nanocubes, from the inner core to the surface, which were interpreted in terms of cubic layers with different distances from the surface using a simple geometrical model. This interpretation was also supported by 133Cs longitudinal relaxation time measurements. [ABSTRACT FROM AUTHOR]

Structurally simple two rod-like mesogens with a three-ring core consisting of biphenyl and phenyl rings are synthesised to investigate the mesophase properties, molecular organisation and the orientational order parameter. In mesogen-1, a dodecyloxy terminal chain is present on the biphenyl ring while the phenyl ring is free from substituent. For mesogen-2, in addition to the dodecyloxy chain, the butyl chain is placed on the phenyl ring. The Hot-stage optical polarising microscopy (HOPM) and differential scanning calorimetry (DSC) measurements show smectic A (SmA), smectic B (SmB), and crystal E (CryE) phases for mesogen-1 and SmA, smectic C (SmC) and smectic F (SmF) phases for mesogen-2. The presence of smectic mesophases is established by X-ray Diffraction (XRD). 1D and 2D 13C solid-state NMR experiments are performed in smectic mesophases to find the orientational order parameters of the phenyl rings of the core. The main order parameter (Szz) of the mesogens in the SmB and SmF phase is in the range of 0.87–0.93. The excellent spectral resolution noticed in 13C NMR spectra in the SmB mesophase (mesogen-1) indicates that the internal rotations of the molecules along the long axis are primarily unhindered. [ABSTRACT FROM AUTHOR]

The basis set issue has always been one of the most important factors of accuracy in the quantum chemical calculations of NMR chemical shifts. In a previous paper, we developed new pecS-n (n = 1, 2) basis sets purposed for the calculations of the NMR chemical shifts of the nuclei of the most popular NMR-active isotopes of 1–2 row elements and successfully approbated these on the DFT calculations of chemical shifts in a limited series of small molecules. In this paper, we demonstrate the performance of the pecS-n (n = 1, 2) basis sets on the calculations of as much as 713 1H and 767 13C chemical shifts of 23 biologically active natural products with complicated stereochemical structures, carried out using the GIAO-DFT(PBE0) approach. We also proposed new alternative contraction schemes for our basis sets characterized by less contraction depth of the p-shell. New contraction coefficients have been optimized with the property-energy consistent (PEC) method. The accuracies of the pecS-n (n = 1, 2) basis sets of both the original and newly contracted forms were assessed on massive benchmark calculations of proton and carbon chemical shifts of a vast variety of natural products. It was found that less contracted pecS-n (n = 1, 2) basis sets provide no noticeable improvement in accuracy. These calculations represent the most austere test of our basis sets as applied to routine calculations of the NMR chemical shifts of real-life compounds. [ABSTRACT FROM AUTHOR]

Composting is described as a sustainable alternative to organic waste reuse from the agricultural and household sectors. The organic matter degradation and stabilization product presents great variability due to the waste composition used. Thus, the use of techniques that allow the monitoring of the decomposition process is necessary to determine the quality of the final product. Therefore, this review critically analyzes and updates the chemical spectroscopy methods described for the evaluation of the organic matter transformation in the composting process to optimize and generate amendments for agricultural use. This review examines spectroscopic techniques such as ultraviolet-visible (UV-Vis), infrared (IR), fluorescence, and 13C NMR reported for the evolution and maturation of carbonate structures in composting. In addition, they are used in the study of indicators for monitoring the degradation of complex structures, such as sugars and proteins, for the formation of precursors that are responsible for the formation of highly stabilized substances such as humic and fulvic compounds. Finally, these parameters may be used to elucidate organic matter degradation and its stabilization process, establish patterns that characterize each stage of composting along with its physicochemical characteristics, and monitor potential phytotoxicity levels. [ABSTRACT FROM AUTHOR]