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The stability and chemical composition of SOM are related to the changes of the proportions of old and young SOM. However, there are few studies that investigated the effects of no-tillage (NT) on the stability, chemical composition, and sources of SOM. In this study, the effects of 9-years of NT on the contents of total, thermally labile and stable SOM, their chemical composition and the contributions from C 3 and C 4 plants were determined. Before application of NT, the field has been used for C 4 maize cultivation under conventional tillage (CT) management about 80 years after initial C 3 grassland reclamation. Soil samples were collected in the 0–20 cm soil profile. Under NT treatment, the contents of total SOC, thermally labile and stable SOC, and C 4 -SOC decreased with soil depths. However, they were greater in the 0–10 cm layers than that in the 10–20 cm layer under CT. The contents of C 3 -SOC showed no change with depths under both of tillage treatments. NT had greater contents of total SOC, C 4 -SOC, thermal-labile SOC, and C 4 -SOC thermal-labile than CT in the 0–5 cm layer, but lower in the subsoil layers. The contents of C 3 -SOC thermal-labile decreased in the 0–5 cm layer under NT. The alkyl-C and O-alkyl-C were the main fractions of thermal-labile SOM and aromatic-C was the dominant fraction of thermal-stable SOM. C 4 -SOC (young SOC) was significantly positively correlated with alkyl-C and O-alkyl-C and negatively correlated with aromatic-C. Our results indicated that: (1) compared with continuously CT, applying NT resulted in SOC accumulation in the surface layer, (2) more maize residue input increased the new thermally labile and stable SOM yet lead to decrease the C 3 -SOC thermal-labile under NT, (3) the contributions of C 3 and C 4 -direved SOM determined the chemical compositions of various SOM pools. • The C 4 -SOC was greater under NT than CT in the 0–5 cm, but lower in 5–20 cm layer. • No-tillage accelerates the decomposition of thermal-labile SOC derived from old C 3 plant. • Alkyl-C and O-alkyl-C are thermal-labile and aromatic-C is thermal-stable. [ABSTRACT FROM AUTHOR]

Microalgae have attracted much attention because of their great potential in the development of sustainable biofuel. In this study, cyanobacteria Schizothrix calcicole was fractionated into different fractions and characterized by elemental analyses, Rock-Eval pyrolysis, and 13C NMR. Closed pyrolysis experiments were carried out on the bulk (BL) sample of S. calcicole and its nonhydrolyzable organic matter (NHOM) fraction. The results suggested the NHOM fraction was composed of a saturated and unbranched or weakly branched hydrocarbon chain with a chain length up to 32, which was highly aliphatic resistant biopolymer similar to algaenan in structure, and exhibited higher oil yield (58.1 %) and oil and gas production potentials (OGPs, 63.9 %) than the BL sample did. Moreover, the n- alkanes for the NHOM fraction showed bimodal distribution and were dominated by long chains higher than C 15. On the contrary, the BL sample exhibited unimodal distribution of n -alkanes, in which middle- and short-chain n -alkanes with chain length <17 were more abundant. In addition, the results indicated 13C NMR is an effective approach to evaluate hydrocarbon generation potentials. Our investigation identifies aliphatic biopolymers in cyanobacteria S. calcicole and improves the understanding of hydrocarbon generation of its different fractions. The biopolymer (NHOM) isolated from one cyanobacteria species comprised of long and saturated hydrocarbon chain unit (up to C32), and exhibited the highest oil yield and hydrocarbon generation potentials. [Display omitted] • The biopolymer was isolated from one cyanobacteria species. • The biopolymer was similar to other algaenan in structure. • The biopolymer exhibited very high oil yield and hydrocarbon generation potential. • The biopolymer exhibited hydrocarbon generation characteristics that are different from the bulk cyanobacteria. [ABSTRACT FROM AUTHOR]

Hordeum vulgare husk, a cereal grain, is rich in dietary fiber and prebiotics beneficial for the gut microbiota and host organism. This study in v estigates the effects of barley husk-derived water-soluble xylan (BH-WSX) on gut homeostasis and the microbiome. We enzymatically extracted BH-WSX and evaluated its prebiotic and antioxidant properties. A 40.0 % (w/v) xylan yield was achieved, with the extracted xylan having a molecular mass of 212.0885 and a xylose to glucuronic acid molar ratio of 6:1. Specialized optical rotation research indicated that the isolated xylan is composed of monomeric sugars such as D-xylose, glucose, and arabinose. Fourier Transform Infrared (FTIR) spectroscopy revealed that the xylan comprises β (1 → 4) linked xylose units, randomly substituted with glucose residues, α-arabinofuranose, and acetyl groups. Nuclear Magnetic Resonance (NMR) analysis showed that the barley husk extract's backbone is substituted with 4- O -methyl glucuronic acid at the O 2 position. Thermogravimetric analysis indicated that WSX exhibits a single sharp peak at 266 °C on the Differential Thermal Gravimetry (DTG) curve. Furthermore, a combination of in vitro, in vivo models, and molecular docking analysis elaborated on the anti-adhesion properties of BH-WSX. This study presents a novel approach to utilizing barley husk as an efficient source of functional polysaccharides for food-related industrial applications. • Enzyme-aided alkaline extraction enhanced polymeric xylan yield from barley husk effectively. • Extracted xylan demonstrated strong anti-biofilm activity. • Barley husk xylan showed high affinity for pathogen cell wall proteins in in silico analysis. • BH xylan's prebiotic effects and gut microbiota modulation were confirmed. [ABSTRACT FROM AUTHOR]

[Display omitted] • We studied SOC fractions and microbial properties in three cover-cropped orchards in China. • Legume cover crops increased SOC more than non-legume covers (38% vs. 16%) • Legume cover crops enhanced enzyme activities, microbial necromass, and community diversity. • Non-legume cover crops negatively affected the ratio of BG to NAG. • Microbial properties dominated the changes in SOC physical fractions. 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. [ABSTRACT FROM AUTHOR]

• MOR outperforms MEA/MAE in CO 2 capture, excels in desorption. • At 7 M, MOR boosts desorption rate by 357.86 % over MEA. • MOR cuts energy use by 33.33% and lowers costs 7.89% vs. MEA. • Industrial potential for MOR due to high thermal stability, low corrosivity. The present study comprehensively evaluates the CO 2 capture performance of morpholine (MOR) at concentrations of 2 M, 5 M, and 7 M, comparing its effectiveness against conventional amines, monoethanolamine (MEA) and 2-(methylamino)ethanol (MAE). The assessment criteria include CO 2 absorption rate, desorption rate, cyclic capacity, regeneration energy consumption, and relative economic cost. Utilizing 13C Nuclear Magnetic Resonance (NMR) technology, we analyzed the variations in ion concentration of the amine solvents under different CO 2 loadings to reveal the reaction mechanisms of MOR with CO 2. Our results demonstrate that MOR outperforms MEA and MAE in CO 2 capture performance, particularly excelling in desorption efficiency. At a concentration of 7 M, MOR exhibited a 357.86% increase in average desorption rate and a 46% larger cyclic capacity compared to MEA. Additionally, MOR showed a 33.33% reduction in regeneration energy consumption and a 7.89% decrease in relative economic cost. The comprehensive evaluation method developed in this study indicates that MOR, with its high thermal stability and low corrosivity, maintains excellent CO 2 capture performance at high amine concentrations, suggesting it as a promising absorbent for industrial applications. The findings contribute to the optimization of amine-based CO 2 capture technologies and provide a robust framework for the selection and assessment of amine solvents, paving the way for more sustainable and cost-effective carbon capture solutions. [ABSTRACT FROM AUTHOR]

Graphene nanoflakes have attracted a growing interest owing to their tunable and unique electronic, optical, and magnetic properties. In particular, recent breakthroughs in the on-surface synthesis and characterization of graphene nanoflakes exhibiting π -magnetism have shown their promising great potential for spintronic applications. In this context, a theoretical investigation on the relative energetic stability, 13C nuclear magnetic resonance (NMR) chemical shifts, magnetically induced currents, hyperfine shifts, and hyperfine coupling constants of graphene nanoflakes of hexagonal and triangular shape has been performed using the density functional theory (DFT). The role played by the size, shape, and atomic site position in the flake on the 13C isotropic chemical shift is thoroughly examined. As a general trend, considering only the orbital contribution, sites from the innermost region of the flake present lower chemical shifts than the ones close to the border and, for large enough systems, such values tend to converge to roughly the graphene one. For the open-shell flakes, the hyperfine shifts and coupling constants exhibit oscillatory behavior, with opposite signs for adjacent sites. The magnitude of these parameters is progressively reduced with the increase in the distance from the edge, where the largest values of excess spin density are concentrated. [Display omitted] ● NMR parameters of graphene nanoflakes are investigated through DFT based simulations. ● Flakes of different sizes and shapes (coronoids and triangulenes) are analyzed. ● Spin-state energy splittings and spin ground state are calculated for triangulenes. ● 13C NMR chemical shifts for coronoids show good correlation with the flake size and atomic site position. ● Spin density and hyperfine shifts show oscillatory behavior for adjacent sites in triangulenes. [ABSTRACT FROM AUTHOR]

Anthracite, a high-rank coal, is an important fossil energy and resource, widely used in combustion and gasification. To improve the utilization efficiency of anthracite, it is important to study its structures. In our previous work, we found that the alkali-oxygen oxidation of anthracite could yield benzene carboxylic acids (BCAs). However, none of the existing structural models of anthracite captures the yield distribution of BCAs. In this work, we studied the structures of Hebi anthracite based on its BCAs combined with multi analysis techniques and proposed a structural model of the coal. We first oxidized the coal to yield BCAs, whose parent structure distributions we then investigated. Then, based the results of ultimate analysis and 13C NMR, we obtained the structural parameters. We then proposed corresponding aromatic clusters based on the parent structures of BCAs. Lastly, we constructed a structural model of the coal based on the analyses of ultimate analysis, 13C NMR, XPS and the contents of carboxyl and phenolic hydroxyl groups. The model has a molecular formula of C 1966 H 882 N 22 O 76 S 3 and a molecular weight of 26094 amu. The model not only reflects the characteristics of anthracite intuitively, but also agrees with the results of BCAs, elemental analysis, carboxyl and phenolic hydroxyl group analyses, XPS analysis, and 13C NMR analysis. The work provides new insights in the structural characteristics of anthracite. • Benzene carboxylic acids were obtained from Hebi anthracite via oxidation. • A structural model of Hebi anthracite was proposed based on the distributions of their yields. • The model has a molecular formula of C 1966 H 882 N 22 O 76 S 3 and a molecular weight of 26094 amu. • The model can reflect the characteristics of anthracite. [ABSTRACT FROM AUTHOR]

• A Mesoproterozoic kerogen molecular model is established for the first time. • This kerogen is mainly short-branched chains or alicyclics rather than long chains. • This kerogen model resembles Paleozoic kerogen, yet differs from Mesozoic kerogen. In the southeastern Xuanlong sag of Northern China, the organic-rich black shale of the Mesoproterozoic Xiamaling Formation holds significant potential as a source rock. Through advanced analytical techniques including elemental analysis, 13C NMR, XPS, FTIR, and XRD, the elemental composition and chemical structure were thoroughly characterized, and the molecular structure of the Xiamaling shale kerogen was established. The 13C NMR analysis revealed the carbon composition of kerogen, indicating 75.19 % aliphatic carbon, 22.06 % aromatic carbon, and 2.75 % carbonyl carbon, with quantitative support from FTIR and XRD spectra. The dominant methylene carbons exhibited a low average methylene chain length (Cn) of 3.87, suggesting that they are primarily short-branched or alicyclic compounds rather than long straight chains. This conclusion was verified by the absence of a sharp peak at a wavenumber of 719.95 cm−1 in the FTIR spectrum. Oxygen-containing functional groups observed in 13C NMR spectra were also identified in FTIR spectra at a wavenumber range of 3500–1000 cm−1. XPS analysis indicated that nitrogen-containing groups were amino, quaternary, pyridine, and primary pyrrole groups, and sulfur existed as sulfoxide, aromatic sulfur, aliphatic sulfur, and sulfone. Finally, a relatively rational 2D molecular structure with the chemical formula of C 278 H 346 N 6 O 26 S 2 was established by comparing the predicted and experimental 13C NMR spectra. Using MD simulation, five optimized 2D molecules were combined to construct a robust 3D kerogen model with a physical density of 1.067 g/cm3. Comparatively, the aliphatic structure of the Mesoproterozoic Xiamaling kerogen model consists of some monocyclic alkanes and polycyclic saturated structures, resembling Paleozoic kerogen models but differing from Mesozoic counterparts. The constructed kerogen model addresses the gap in the Precambrian kerogen modeling and sets the stage for in-depth exploration of pyrolysis mechanisms in the future. [ABSTRACT FROM AUTHOR]

In this article, the functional group composition of the spruce (Pícea ábies) and birch (Bétula péndula) phloem lignin is described. The features of the chemical structure were studied by analyzing dioxane lignin using the elemental analysis, UV–Vis, FT-IR, and 1D NMR spectroscopy. For comparison, samples of xylem dioxane lignin isolated from the corresponding wood species were also analyzed. FT-IR spectroscopy data suggest that the lignins of birch phloem and xylem are similar in chemical structure. However, there are differences in absorption bands in the spectra of spruce dioxane lignin, which indicate the opposite. Quantitative analysis of the functional group composition was performed using 13C and 31P NMR data. It was found that free phenolic hydroxyl groups of catechol and p -hydroxyphenyl types are dominated in the composition of spruce phloem lignin. Birch phloem lignin has a qualitative and quantitative composition of functional groups characteristic of hardwood lignins. However, the content of G-units is greater than S-units, in contrast to the birch xylem lignin, where S-units predominate. The revealed differences are relevant from the point of view of plant physiology. The practical significance of the study is connected with understanding the reactivity of lignins when considering the chemical processing of tree bark. [ABSTRACT FROM AUTHOR]

Herein we describe the interaction of starch, urea, and melamine (C 3 N 6 H 6) in composite materials for use as controlled-release plant fertilizer. Slow-release fertilizers are important in minimizing nutrient losses due to run-off, leaching, and other factors. Urea is an effective plasticizer for starch and is an important nitrogen fertilizer throughout the world. Melamine also has high nitrogen content and could be combined with urea-starch composites to provide enhanced controlled-release fertilizer. This study reports the structural interaction and the performance gain of melamine addition to starch-urea composites. Composites were characterized by spectroscopic techniques (FT-Raman and 13C NMR) detailing the interaction between melamine, urea, and starch. These interactions helped facilitate extrusion processing by lowering viscosity and processing temperatures suggesting an enhanced starch plasticizing effect of starch-urea-melamine composites. Further research into the co-plasticization of starch by urea and melamine could be exploited for improved controlled-release fertilizer products. Further research into the co-plasticization of starch by urea and melamine could be exploited for improved controlled-release fertilizer products. [ABSTRACT FROM AUTHOR]

• Isolation, biochemical and molecular characterization of human milk isolates. • Probiotic Characterization for the Isolated lactic acid bacteria. • In vitro antimicrobial activity – Disc diffusion and Growth curve MIC method. • Antimicrobial peptide characterization and molecular interaction Antimicrobial mechanism – Post biotic efficacy towards pathogens. • Safety on Probiotic based on ex vivo analysis, in-vivo C. elegans and mice model. Human-milk-based probiotics play a major role in the early colonization and protection of infants against gastrointestinal infection. We investigated potential probiotics in human milk. Among 41 Lactic acid bacteria (LAB) strains, four strains showed high antimicrobial activity against Escherichia coli 0157:H7, Listeria monocytogenes ATCC 15313, Bacillus cereus ATCC 14576, Staphylococcus aureus ATCC 19095, and Helicobacter pylori. The selected LAB strains were tested in simulated gastrointestinal conditions for their survival. Four LAB strains showed high resistance to pepsin (82%–99%), bile with pancreatine stability (96%–100%), and low pH (80%–94%). They showed moderate cell surface hydrophobicity (22%–46%), auto-aggregation abilities (12%–34%), and 70%–80% co-aggregation abilities against L. monocytogenes ATCC 15313, S. aureus ATCC 19095, B. cereus ATCC 14576, and E. coli 0157:H7. All four selected isolates were resistant to gentamicin, imipenem, novobiocin, tetracycline, clindamycin, meropenem, ampicillin, and penicillin. The results show that Pediococcus acidilatici is likely an efficient probiotic strain to produce < 3 Kda pediocin-based antimicrobial peptides, confirmed by applying amino acid sequences), using liquid chromatography mass spectrometry and HPLC with the corresponding sequences from class 2 bacteriocin, and based on the molecular docking, the mode of action of pediocin was determined on LipoX complex, further the 13C nuclear magnetic resonance structural analysis, which confirmed the antimicrobial peptide as pediocin. [ABSTRACT FROM AUTHOR]

The isomerism of 1,5-benzodiazepin-2-ones 3 containing a perfluorinated side chain was investigated by 1H-, 13C-, 15N- and 19F NMR spectroscopy in different solvents. Compounds 3 exist in CDCl 3 , (D 6)acetone, CD 3 CN and (D 5)pyridine solution as one species, whereas in (D 6)DMSO and (D 7)DMF partial (E / Z) isomerisation about the exocyclic C2=C3 bond occurs resulting in two isomers. Gibbs free energies (ΔG) and Free activation energies (ΔG≠) were calculated based on BP86 and BP86-SCRF DFT computations. Image 1 • Fluorine containing 1,5-Benzodiazepin-2-ones exist in solution as one isomeric form due to an intramolecular hydrogen bond. • In solvents that are both polar and basic a second isomer appears to a certain amount. • The new isomer is formed by breaking off the hydrogen bond and (E / Z) isomerisation about an exocyclic double bond. • The isomerism was investigated by 1H-, 13C-, 15N- and 19F-NMR spectroscopy in different solvents. • Gibbs free energies (ΔG) and Free activation energies (ΔG≠) were calculated based on DFT computations. [ABSTRACT FROM AUTHOR]

Cottonseed protein is a potential alternative to formaldehyde-based adhesives as a renewable resource without negative environmental impact in use. Like other protein-based adhesives, unmodified cottonseed protein isolate needs improved water resistance. Thus, in this work, the effects of phosphoric acid (H 3 PO 4), dipotassium hydrogen phosphate (K 2 HPO 4), calcium oxide (CaO), and calcium hydrogen phosphate (CaHPO 4) at four concentrations (i.e., 20, 40, 60, and 80 mM) on the adhesive strengths of cottonseed protein isolate were evaluated. Compared with control (protein without modifiers), H 3 PO 4 (20 and 40 mM) increased dry, wet, and soaked strength by 20–30, 72–88, and 24–30%, K 2 HPO 4 (40 and 60 mM) by 8–22, 2–10, and 1–8%, CaO (20 and 40 mM) by 8–16, 11, and 6%, and CaHPO 4 (40, 60, and 80 mM) by 12–26, 6–13, and 7–14%, respectively. Cottonseed protein with 40 mM H 3 PO 4 had the best adhesive performance, especially water resistance (88% higher in the wet strength than control), due to the increased crosslinking at its isoelectric point caused by acidity of H 3 PO 4 (pH, 4.13). Solid state 13C nuclear magnetic resonance spectroscopic analysis showed that the amino groups interacted with these P compounds in the blending adhesives. Finally, an optimized protein adhesive preparation was applied to bond 3-ply pine plywood. The water resistance of these 3-ply strips passed the industrial soak test as Type II plywood used for hardwood and decorative plywood, indicating that the adhesive under optimal conditions can be used as a green and environment-friendly adhesive resource in wood industry. Image 1 • The adhesive properties of cottonseed protein improved by phosphorus additives. • P compounds interacted with the amino groups of cottonseed protein in the blending adhesives. • Three-ply plywood panel prepared by optimized cottonseed protein-based adhesive. • The plywood strips passed the industrial test as Type II plywood for indoor no-structural application. [ABSTRACT FROM AUTHOR]

In this paper, a 400 ppm aqueous solution of guar gum polysaccharide was submitted to a turbulent flow regime in order to monitor molecular degradation and drag reduction. Guar gum samples were isolated and analyzed by spectroscopic, thermoanalytical and viscosimetric techniques. The drag reduction promoted by guar gum is compromised as the polysaccharide undergoes degradation. Viscosimetric analysis of guar gum showed a reduction in viscous molecular mass. Mid-infrared spectra and hydrogen nuclear magnetic resonance suggest that mechanical degradation promotes hydrolysis of the glycosidic bond α (1 → 6) releasing (d)-galactose owing to the appearance of the carbonyl functional group. Thermal analysis revealed the reduction of the polysaccharide's thermal stability by reduction of the polymer chain. A comprehensive analysis of these combined parameters affords a foundation for the development of more efficient biopolymers in the context of improved drag reduction. • Guar gum was analyzed by spectroscopic, thermoanalytical and viscosimetric techniques. • Guar gum drag reduction submitted to a turbulent flow regime was monitored. • The drag reduction is compromised as the polysaccharide undergoes degradation. • Viscous molecular mass of guar gum is reduced over time. [ABSTRACT FROM AUTHOR]

• We propose theoretical approach to distinguish C 60 bis-cycloadducts. • Cross-comparison approach allows distinguishing between C 60 bis-cycloadducts. • RMSE values after empirical corrections decreased from 3.45 to 1.41 ppm. In this work, we propose a theoretical approach to distinguish fullerene C 60 bis-cycloadducts with identical addends giving the same number of 13C NMR signals of sp2 fullerene carbon atoms. Trans -1 C 60 bis-cycloadducts, including those that bear different addends, may be assigned from their unique number of 13C NMR signals of sp2 fullerenyl carbon atoms (6 × 8C + 2 × 4C) compared with the remaining bis-cycloadducts. The same is typical of equatorial C 60 bis-cycloadducts (27 × 2C and 2 × 1C). A distinctive feature to distinguish trans -2, trans -3, and cis -3 C 60 bis-cycloadducts with identical addends, giving equal number of 13C NMR signals of sp2 fullerenyl carbon atoms, is a high correlation coefficient obtained after cross-comparison between their experimental and theoretical 13C NMR CSs. Similar cross-comparison may be applied to trans -4, cis -1, and cis -3 C 60 bis-cycloadducts with identical addends. The RMSE values after empirical correction to theoretical 13C NMR CSs of sp2 fullerenyl carbons decreased from 3.45 to 1.41 ppm. This is an effective way to decrease the error of GIAO-X3LYP/6-31G method, which probably does not fully take into account the contribution of magnetic ring currents to the magnetic shielding of sp2 fullerenyl carbon atoms. The proposed cross-comparison was verified on a test set of regiosiomeric C 60 bis-cycloadducts not involved into the training set, which led to unambiguous structural assignments. [ABSTRACT FROM AUTHOR]

• The guest-host interaction of the semi-clathrate hydrate was studied by 13C NMR. • The interaction and guest mobility in the range of 230–264 K were revealed. • The number of 13C NMR signals was different depending on the carbon position. • The cation's local structure was drastically changed with decreasing temperature. We report changes in the 13C NMR spectra of tetra- n -butylammonium (TBA) cations by clathrate hydration of TBA chloride (TBAC), which is a quaternary ammonium salt known to form a semi-clathrate hydrate expected as gas capture or cold storage materials. Clathrate hydration decreased the number of 13C NMR signals of the four carbons in comparison to the corresponding carbon signals in the solid phase at same temperatures. This is caused by the overall broadening of the signals due to incorporation of TBA cations into the hydrate framework, suggesting that the guest mobility is restricted by clathrate hydration. Furthermore, a comparison of the 13C NMR spectra between the TBAC hydrate and solid-state TBAC in the temperature range of 230–264 K suggested that having the rigid hydrate framework tended to restrict the guest mobility and changes in the local interaction of guest TBA cations with the hydrate framework with decreasing temperature. [ABSTRACT FROM AUTHOR]

Abstract Knowledge of organic matter transformation under simulated rapid composting is essential for the understanding of biodegradation processes. Herein, several technologies, including atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and 13C Nuclear Magnetic Resonance Spectroscopy (13C NMR) were used to gain insight of the composition and architecture of the substrate during biodegradation. The total carbon of the substrate was decreased by 27.7% compared to the initial content, while the total nitrogen was increased from 1.1% to 1.8% at the end. The water soluble carbon, water soluble nitrogen and hydrolytic enzyme activities fluctuated strongly between 3 and 14 days, which was considered as the active stage of the composting process. The appearance of microfibers and deep ditch indicated that the tunneling might be one of the mechanisms of the composting microorganisms to degrade the lignocellulose. The X-ray photoelectron spectroscopy (XPS) analysis results showed that the main degradable carbon component was C1 (containing C-H or C-C bonds), which was decreased by 25.5% compared to the initial substrate. The 13C NMR analysis showed that the O-alkyl-C group dominated the resonance signals in all treatments ranging from 76.6% to 83.1% and alkyl-C fluctuated from 8.1% to 10.2%, indicating the effective degradation of lignocellulose. In summary, the combination of morphological observations by atomic force microscope (AFM) and the chemical analysis by XPS and 13C NMR is a promising approach for the characterization of agricultural wastes biodegradation process. Graphical abstract Image 10181 [ABSTRACT FROM AUTHOR]

Abstract Molecular model construction is essential for the study of the energy conversion process, the combustion reaction mechanism and the clean utilization of coal. In this study, an anthracite molecular structure of GBW(E)110031 was constructed based on the structural accuracy identification methods, such as 13C nuclear magnetic resonance spectroscopy (13C NMR), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and quantitative chemical analysis. The 13C NMR spectrum was registered to analyze the carbon skeleton structure of the anthracite and twelve characteristic parameters of coal structures. The aromaticity, hydrogen aromaticity, and average aromatic nuclear size of the anthracite were calculated. These data were utilized to construct 17 basic structural units of aromatic carbon. The vibration modes of the carbon skeleton, several association forms of oxygen, and different types of functional group were confirmed based on the ATR-FTIR collected spectra. The content of functional groups and unsaturated aliphatic carbon alkenyl were determined by the calcium ion exchange method, the pyridine hydroxylamine hydrochloride oximation method and the bromine addition method. Based on these experimental data, a C 202 H 104 O 21 N 2 S 2 anthracite molecular structure model was constructed. In the molecular structure model, benzene and naphthalene structures accounted for 70% of the mass of aromatic compounds, while aliphatic structures existed in the form of side chains and rings. Carbonyl group (C O) accounted for 85% of the oxygen atoms, while others existed in the form of carboxyl and hydroxyl groups. The nitrogen atoms presented in the structures of pyridine and pyrrole, and the sulfur atoms presented in the structures of thiophene. The theoretical analysis matched well with 13C NMR spectra interpretation, which was verified the reliability and rationality of the molecular structure model and analytical method. Highlights • A new anthracite molecular model is proposed which is C 202 H 104 O 21 N 2 S 2. • The structure accuracy is improved by adding unsaturation in the construction of molecular model. • The experiments show that the predicted spectrum of structure model matched well with 13C NMR spectra results. [ABSTRACT FROM AUTHOR]

Abstract In a previous study, we reported that Curcuma longa strain Ryudai gold (RD) showed antifungal activity against Fusarium solani sensu lato (FSSL) among the different species and varieties of turmeric. The present study focused on isolation, identification and structural elucidation of antifungal compounds in RD. The ethyl acetate (EtOAc) fraction was eluted with n -hexane and EtOAc with gradually increasing the concentration of EtOAc (n -hexane:EtOAc; 100:0; 80:20; 60:40, 40:60, 20:80 and 0:100). The antifungal compounds were isolated from the most effective fraction by using silica gel, TOYOPEARL® HW-40F column, and high-performance liquid chromatography. Structural identification of the antifungal compounds was conducted using 1H NMR, 13C NMR, and liquid chromatography-tandem mass spectrometry. The MeOH extract of the rhizome of RD inhibited the growth of FSSL in a concentration-dependent manner. The EtOAc fraction of the MeOH extract of RD demonstrated the highest antifungal activity against FSSL. The purified antifungal compounds were turmeronol B (1), turmeronol A (2), (E)-α-atlantone (3), dihydrobisdemethoxycurcumin (4), demethoxycurcumin (5) and curcumin (6). These six compounds showed concentration-dependent antifungal activity against FSSL. The concentration required for 50% growth inhibition (IC 50) of the four isolates of FSSL ranged from 116 to172, 127 to 185, 88 to 109, 90 to 112, 74 to 80 and 63 to 68 μM/L for turmeronol B, turmeronol A, (E)-α-atlantone, dihydrobisdemethoxycurcumin, demethoxycurcumin and curcumin, respectively. These results suggested that RD contained potential antifungal compounds that could be useful to control FSSL. The isolated compounds of RD can be a good source of natural antifungal agents or the lead compounds for the development of new synthetic drugs. Graphical abstract Unlabelled Image Highlights • Ryudai gold is a strain of C. longa developed by the University of the Ryukyus and registered by the Ministry of Agriculture, Forestry and Fisheries, Japan. • We have purified 6 potential antifungal compounds namely turmeronol B (1), turmeronol A (2), (E)-α-atlantone (3), dihydrobisdemethoxycurcumin (4), demethoxycurcumin (5) and curcumin (6). • The purified compounds showed concentration-dependent antifungal activity against Fusarium solani sensu lato. [ABSTRACT FROM AUTHOR]

Abstract Soil organic matter (SOM) changes with land use and soil management, yet the controlling factors over the chemical composition of SOM are not fully understood. We applied quantitative 13C nuclear magnetic resonance and spectral editing techniques to measure chemical structures of SOM from different land use types. The land use types included a native grassland (nGL), a crop land with straw burning in the field (bCL), a restored grassland (rGL) and a cropland with straw removed out of the field (rCL) for 28 years. The abundances of O CH groups from carbohydrates were higher in the SOMs of the nGL and rGL than in those of the rCL and bCL, while the abundances of OCH 3 and aromatic C O groups from lignin were higher in the SOMs of the three-ever cultivated lands (rGL, rCL and bCL) than in that of the nGL. Although aromatic C C groups were most dominant in the Mollisols, they did not consistently decrease after the burnings of straw were ceased in the fields of the rCL and rGL compared to the bCL with continuous burning. In addition, the COO groups were bound with the aromatic C C groups in all the land use types, and the sizes of the aromatic clusters were affected by the land use types. The labile and recalcitrant components were correlated with SOC contents the mineral-associated and particular SOM in a contrasting way. Our results suggested that the chemical composition of SOM in the Mollisol depended on land use types, and that labile and recalcitrant components might be protected through mineral associations and aggregation, respectively. The most abundant aromatics in the Mollisols might not just be pyrogenic and could be oxidized to different extents, depending on field drainage conditions. Graphical abstract Unlabelled Image Highlights • Restored and native grasslands were compared with croplands with straw removed and burnt • Long-term cropping from native grassland resulted in decreases in carbohydrates and increases in lignin • No straw burning increased lignin oxidization and reduced the size of aromatic cluster • Labile and recalcitrant components may be protected in light and heavy fractions, respectively [ABSTRACT FROM AUTHOR]

Abstract Exploration of non-edible oil as a feedstock and the use of new heterogeneous nanocatalyst could contribute to bioenergy research. In this regard, the present work is focussed on the use of cobalt doped zinc oxide nanocatalyst for production of biodiesel from Mesua ferrea oil. The synthesized catalyst has been analyzed through X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Thermogravimetric analysis (TGA) techniques. Under optimal reaction condition, maximum biodiesel conversion of 98.03% was obtained in 3 h at 60 °C with 2.5 wt% catalyst loading and 1:9 oil to methanol molar ratio. The produced biodiesel has been characterized using Proton Nuclear Magnetic Resonance (1H NMR), Carbon Nuclear Magnetic Resonance (13C NMR) and Gas Chromatography-Mass Spectroscopy (GC-MS) techniques. Fuel properties of the produced biodiesel have also been determined. The result showed good catalytic activity of cobalt doped Zinc oxide nanocatalyst and could be used for large scale biodiesel production from Mesua ferrea oil by further enhancing its stability. Highlights • Co doped ZnO nanocatalyst was synthesized via co-precipitation method. • The catalyst shows good catalytic activity and high percentage of conversion.. • The best operational condition found to be oil: methanol = 1:9 at 60 °C for 3 h. • Co doped ZnO catalyst can be used for large scale biodiesel production. • The catalyst can be reused for further transesterification reaction. [ABSTRACT FROM AUTHOR]

Abstract Carbon (C) stabilization and the quality of soil organic matter (SOM) in a tropical climate are key aspects regulating carbon dioxide emissions and maintaining the C cycle. Soil management influences the accumulation of C, regulating the balance between mineralization and/or the humification of SOM. This study aimed to quantify inputs of different chemical forms of C into soil and to evaluate the structural chemical characteristics of humified SOM. Four management systems were established: Forest (F), Pasture (P), Conventional tillage (T), and No-tillage (NT). Total organic carbon (TOC) and nitrogen (TN) by depth, chemical forms of organic matter input, and spectroscopic characterization of SOM in the form of humic acids (HA) were analyzed. The results obtaining by PCA-13C NMR show that the forest accumulated a high amount of C on the surface (surpassing 20 Mg ha−1), favoring the formation of aliphatic HA (C Alkyl -H,R; C Alkyl -O,N; C Alkyl -O). In the NT management that increases biomass in the soil (14 Mg ha−1), the mineralization process occurred to a greater extent, allowing HA to form with a predominance of aromatic structures (C Arm -H,R and C Arm -O,N). The PCA-FTIR analysis showed that the P system contributed to the formation of similar HA to those under F management. The T management system incorporated the least TOC and TN, with different HA types being formed in these soils than what was found in other managements. Thus, minimally managed and more stabilized systems in tropical climates form HA of structural and compositional similarity, regardless of the nature of C (C3 or C4). In contrast, soils subjected to agricultural uses that promote higher or lower C inputs, form HA that are structurally different from P and F. This study demonstrates the need for developing experiments for model building to elucidate the relationships among C input, management type, and the formation of humic substances. Graphical abstract Unlabelled Image Highlights • Stabilization of SOM depend of the quantity and type of structures deposited in soil. • Forest facilitates the high accumulation of C-aliphatic structures on the soil surface. • Poorly managed soils yield HA with similar structure and composition between them. • Crop systems produced HA structurally differentiated when compared to forest. [ABSTRACT FROM AUTHOR]

Abstract Stereochemistry of N-nitroso-2r,6c-diphenylpiperidin-4-one oxime (1) , N nitroso -3t-methyl-2r,6c-diphenylpiperidin-4-one oxime (2) , N nitroso-3t-isopropyl -2r,6c-diphenylpiperidin-4-one oxime (3) , N nitroso-3t-ethyl-2r,6c-diphenylpiperidin-4-one oxime (4) has been studied using 1H, 13C and two-dimensional NMR spectra. Analysis of the spectral data shows that in 2, 3 and 4 the NOH group is anti to the alkyl group at C-3. All the four compounds seem to exist largely in boat conformations with one phenyl group in the flagpole position. Analysis on the reported spectral data on N nitroso -2r,6c-diphenylpiperidin-4-ones suggests that these compounds also largely exist in boat conformations with one phenyl group in the flagpole position. Chair conformation with axial phenyl groups may contribute to some extent. The relative populations of the boat and chair conformations have been supported by the observed NOEs in their NOESY spectra. Graphical abstract Image 1 Highlights • N-nitroso-2r,6c-diphenylpiperidin-4-one oxime (1) , ans some N nitroso -3t- alkyl-2r,6c-diphenylpiperidin-4-one oximes (2–4) , has been synthesized and its stereo chemistry has been studied. • The assignment of signal and conformations has been studied for compound 1–4 using COSY, coupling constant and NOESY spectra. • The compounds 1 &2 seem to exist largely in boat conformations. • The compounds 3&4 seem to exist as an equilibrium mixture of both chair and boat conformations. • The relative populations of the boat and chair conformations have been supported by the observed NOEs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of UF resins in the wood-based composites. • Effects of catalysts (NH 4) 2 SO 4 , NH 4 Cl, H 2 SO 4 and HCl during UF resins synthesis. • Investigated by 13C NMR and DSC. • (NH 4) 2 SO 4 catalyzed UF adhesive with the best overall mechanical properties. • The HCl catalyst was considered to be chemically least active. Abstract Recently, there has been a rapid growth in research and innovation in the synthesis of UF resins in the wood-based composites area. Much effort has gone into increasing their mechanical performance to extend the capabilities and application of this group of materials. This paper, for the first time, defines the research on the use of ammonium salts not as hardeners but in the synthesis of UF resins. The objective of this study was to investigated the effects of various types of catalysts (ammonium sulfate, ammonium chloride, sulfuric acid and hydrochloric acid) during UF resins synthesis on formaldehyde emission and characteristics of urea–formaldehyde (UF) adhesives for the manufacture of medium density fiberboard. These were investigated by 13C Nuclear Magnetic Resonance (13C NMR) and differential scanning calorimetry (DSC), and as a result some of the physical and mechanical properties of medium density fiberboard (MDF) panels bonded with different UF resins were evaluated. The resins structure examined by 13C NMR spectroscopy showed that a resin catalyzed by (NH 4) 2 SO 4 had a higher proportion of hydroxymethyl groups (mostly HN C H 2 OH) resulting in a higher level of formaldehyde emission. A resin catalyzed by NH 4 Cl gave the highest proportion of methylene groups. A resin catalyzed by H 2 SO 4 yielded the highest proportion of methylene groups in di- or tri-substituted ureas but the lowest proportion of mono-substituted urea. It was of interest that (NH 4) 2 SO 4 catalyzed UF adhesive yielded the best overall mechanical properties for the medium density fiber board (MDF) bonded with it. Conversely, it also presented the shortest shelf life and gelled in about 15 days, which could be related to its high reactivity and shortest gel time. Medium Density Fiberboard (MDF) panels bonded with UF adhesives without any ammonium salt (thus with either H 2 SO 4 or HCl) had lower IB strength, MOR and MOE. The HCl catalyst was considered to be chemically least active, yielding the lowest cohesive energy, and resulted in panels presenting a poor performance as shown by their lowest IB (internal bond) strength, modulus of elasticity (MOE), and modulus of rupture (MOR) and highest thickness swelling, with the exception of the free formaldehyde content. [ABSTRACT FROM AUTHOR]

Abstract Random Forest (RF) technique has been shown to be promising in the supervised classification applied in different matrices. However, approaches to identifying significant variables that weight the model are scarce, in the classification problems. In this paper, we propose a methodology for the selection of variables of greater relevance in the construction of RF models. For the application of this methodology, classification models were developed to discriminating crude oil samples, about to their maximum pour point (MPP). In this sense, data from MPP (ASTM D5853) of 105 crude oil samples, their hydrogen (1H) NMR spectra and carbon (13C) NMR spectra were acquired. With MPP ranging from −54 °C to 39 °C, two classes were assigned: the first containing 43 samples with MPP value ≤ −9 °C, and, the second, 62 samples with MPP value > −9 °C. The 1H NMR models, with 90% accuracy, and 13C NMR, with 71% accuracy, were used in the selection of variable method. The results showed that the methodology proposed to select variables was effective in the distinction of the variables that best contributed to the discrimination of oils. Therefore, this new tool enabled a greater understanding of the interest chemical information, contained in the spectra and its relationship with the MPP property of the crude oil samples. Highlights • RF was applied to discriminate petroleum samples in relation to the maximum pour point. • 1H NMR and 13C NMR are efficient in discriminating samples in relation to pour point. • More important variables of the RF model were identified. • The maximum pour point depends on the equilibrium between saturated, aromatic and polar contents. [ABSTRACT FROM AUTHOR]

Plant residue decomposition is a core process in the soil carbon (C) cycle. Soil nitrogen (N) status regulates organic C chemical structure during crop residue decomposition and subsequent C sequestration significantly. Therefore, understanding how soil N status influences changes in organic C chemical structure during residue decomposition is crucial for effective C management in croplands. In this study, maize (M) and potato-monoculture (P) soils with two N statuses (N0, unfertilized; and N2, 250 and 125 kg N ha−1 for M and P, respectively) were used as decomposition environments to conduct 6-month decomposition of maize and potato residue. According to the results, soil N status had no significant effect on mass loss but changed the organic C chemical structure for both residues. Alkyl C and aliphaticity increased in maize residue but decreased in potato residue under N2 relative to under N0. High N availability increased bacterial-fungi interactions, abundance of cellulose and chitin degradation genes (exoglucanase and chitinase), and enzyme activity (chitinase and sucrase) in maize residue. However, the response of potato residue to N status was opposite to that of maize residue. The structural equation model indicated that the increase in soil NO 3 −-N reduced residue C/N, changed microbial community structure and keystone species in residues, and increased enzyme activities, in turn altering recalcitrant C contents in the decomposed residues. Our results highlight the differential impact of soil N status on organic C chemical structure in different residues, and the coupling relationship between microbial communities and organic C structure during residue decomposition in farmland soil. [Display omitted] • Soil N status had no effect on the mass loss of both crop residues. • High N availability decreased recalcitrant C difference between residues. • Soil N status differently affect bacteria-fungi interaction between residues. • N status regulates the relationship between microbial and residue C groups. [ABSTRACT FROM AUTHOR]

• Structures of coal and residue are corelated with liquefaction condition and yield. • Structure parameters are f al , C n , δ -C/O for cracking, f ar and X b for condensation. • Residues condense in two trends vs. residue yield (Y Res) demarcated by 420 °C. • H consumed per Y Res is low and linear at lower T, high and nonlinear at higher T. To understand the formation of residues and its relation with the vitrinite structure and the products yield in direct coal liquefaction (DCL), a high vitrinite low-rank coal, Naomaohu (NMH), is studied at 380–460 °C in the presence of tetrahydronaphthalene and absence of a catalyst. The structures of coal and residues are characterized by the proximate and ultimate analyses, 13C nuclear magnetic resonance, and the electron spin resonance. Beside the frequently seen coal conversion and products yield at various temperatures and time, the products yield and the residues structure parameters are correlated with the residues yield (Y Res) and the quantity of hydrogen donated from tetrahydronaphthalene (Q H). It is found that the DCL can be roughly defined into two regions demarcated by 420 °C, with limited condensation at 380–400 °C and intensive condensation at 440–460 °C, for example. These two-region behaviors can be clearly evidenced by the different trends in products yield and the residues parameters, such as those relevant to the cleavage of bridge bonds (f al , C n , δ -C and δ -O) and those relevant to the residues' condensation (f ar , X b , R D and H/C), against Y Res and Q H. The two-region behavior is important for optimization of DCL conditions and its processing scheme. [ABSTRACT FROM AUTHOR]

• The molecular structure characteristics of 3 different rank coals were explored. • Three coal molecules of different coal grades were constructed. • The molecular models of three different coal grades were optimized. To investigate the structural properties of coal molecules with different degrees of metamorphism, in this study, we used Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and solid-state nuclear magnetic resonance carbon spectroscopy (13C NMR) to investigate the structural properties of three coal molecules with different degrees of metamorphism and finally constructed and optimized the coal molecular model. The experimental results showed that with the deepening of the deterioration degree, the proportion of oxygen-containing functional groups in the coal molecules was gradually reduced, the long fatty chains were shortened and reduced, and the aromaticity was enhanced. With increasing coalification, pyridine nitrogen and thiophene sulfur are becoming important components of the nitrogen- and sulfur-containing organic matter in coal. Coal metamorphism promotes the aromatization and condensation degree increase of coal molecular structure, which makes the coal molecular structure evolve into a microcrystalline structure with higher order degree. With this increase of coal rank, the carbon ratio around the bridge (X BP) increased from 0.12 to 0.47. The low-rank coal was dominated by benzene rings with low polymerization degree, and the high rank coal was dominated by aromatic structures, such as tetracene with a high degree of polymerization. The molecular formula of lignite finally constructed was C 219 H 159 O 21 N 3 , that of coking coal was C 235 H 164 O 7 N 4 S, and that of anthracite was C 286 H 108 O 5 N 4 S. The coal molecules constructed in this study provide a theoretical basis for the study of the molecular structure properties of coal with different degrees of metamorphism. [ABSTRACT FROM AUTHOR]

Regioselectivity of the Chan–Lam coupling of ambident nitropyrazoles with trans -styrylboronic acid depends on the base and catalyst nature and can vary the N(1)/N(2)-isomer ratio from ∼2 : 1 to ∼1 : 2. 2-Methyl-4-nitro- and 2,4-dinitroimidazoles are unreactive in this reaction. The structure of N(1)/N(2) isomers was elucidated by NOE measurements and by the comparison of experimental and DFT calculated 13C NMR chemical shifts. [ABSTRACT FROM AUTHOR]

Abstract Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [ Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state 13C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time. Graphical abstract Unlabelled Image Highlights • Bioenergy by-products can be used to replenish the soil organic C (SOC). • Fermentation by-product (FBP) and pyrolysis by-product (biochar) increased SOC. • Biochar increased soil recalcitrant C whereas FBP increased soil labile C. • FBP amendment can be used to stimulate microbial response in soils. • Biochar could be used to facilitate C sequestration over time. [ABSTRACT FROM AUTHOR]

Abstract Spectroscopic studies-based on 1D (1H NMR, 13C NMR), 2D-NMR (COSY, HMBC, HSQC), UV–visible, FTIR techniques and quantum chemical studies established on the density functional theory (DFT) were carried out for the natural withanolide glycosides, isolated from Withania Coagulans Dunal. The new glycoside withanolide named as (20R,22R)-14α,17,20β,27-trihydroxy-1-oxowitha-5,24-dienolide-27β-(O-β- d -glucopyranoside) (1), and a known withanolide (20R,22R)-14α-20β,27-trihydroxy-1-oxowitha-5,24-dienolide-3β-(O-β- d -glucopyranoside) (2) are reported here from W. coagulans. The molecular mass of these compounds were confirmed through Fast Atom Bombardment Mass Spectrometry (FAB-MS). Geometric and spectroscopic detailed were obtained from DFT calculations. 1H and 13C NMR theoretical values were found a little higher than the experimental values, but the trend in the chemical shift correlates well with the experimental values. The RMSD values of 1H and 13C NMR of 1 and 2 were 0.4 and 0.38, and 4.94 and 5.02 respectively. The calculated band gap was found 4.93 and 5.00 eV for 1 and 2 respectively which indicated the stable nature of these compounds towards redox reactions. Graphical abstract Image 1 Highlights • Isolation of a new and known withanolide glycosides from withania coagulans. • IR, UV–vis. 1D- and 2D- NMR data of the isolated compounds. • Quantum chemical calculation based on DFT studies. • DFT study proposes high resistivity towards redox reaction. • Similar location in both compounds of HOMO and LUMO with high band gap. [ABSTRACT FROM AUTHOR]

Abstract In the last couple of years growing attention is paid to environmental concerns with a special attention to bio- and renewable resources as feedstock for the chemical industry. In this article we synthesized bio-based high molecular weight epoxy resins with hydroxylated soybean oil (SMEG) and a low-molecular-weight epoxy resin (EPR 0162), using the epoxy fusion process. The course of the synthesis was studied by means of Matrix-Assisted Laser Desorption/Ionization time of flight (MALDI-TOF) mass spectrometry and NMR spectroscopy. A two-stage change in the value of the epoxy and the hydroxyl value, as well as the weight average molecular weight were observed during the SMEG_EPR polyaddition reaction. As a result of the reaction between functional groups, the product of the reaction of one molecule of SMEG and one molecule of EPR (1SMEG+1EPR) is formed. Then it reacts with subsequent molecules of EPR or SMEG with the creation of products: 1SMEG+1EPR, 1SMEG+2EPR, 2SMEG+1EPR. It is also shown that the obtained adducts are not the main products of the analyzed reaction, but are the intermediate reagents throughout the formation of products with higher molecular weights. Based on the progress of the SMEG_EPR epoxy fusion process in the registered m/z range, it has been found that products with linear, rather than branched, structure are more likely to be formed. At the same time this discovery states about less likelihood of crosslinking of the system based on modified soybean oil. Graphical abstract Determination of the structure of products obtained during the epoxy fusion process of high-molecular weight epoxy resins using hydroxylated soybean oil and bisphenol A based epoxy resin. Image 1 Highlights • Soybean oil modification and application in the synthesis of novel epoxy materials. • Synthesis of bio-based epoxy resins via the epoxy fusion process using hydroxylated soybean oil and a low-molecular-weight epoxy resin. • Determination of the course of the synthesis by means of MALDI-TOF mass spectrometry and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Highlights • FAME produced from pretreated waste cooking oil using microwave. • Statistical model developed to optimize biodiesel yield. • RSM and ANN were employed for process optimization. • Produced biodiesel characterized by FT-IR, GC–MS, NMR etc. Abstract Fatty acid methyl esters (FAME) were synthesized from the waste cooking oil (WCO) by direct transesterification with methanol. The WCO was pretreated to increase the efficiency of FAME production with 1% of potassium methoxide as a catalyst. The free fatty acid of raw source was reduced using 2% of activated charcoal as adsorbent. The process variables were optimized using Box-Behnken design of Response Surface Methodology (RSM), and developed Artificial Neural Network (ANN) model to predict the FAME yield. The highest percentage of conversion (95%) was achieved at optimum conditions, for the catalyst concentration of 1%, alcohol to oil ratio of 6:1, temperature of 75 °C and time of 60 s. The yield of biodiesel was estimated by higher R2 values of RSM (0.98) and ANN (0.99), respectively. The produced FAME from pretreated WCO at 75 °C by microwave irradiation was examined by proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FT-IR) spectroscopy, and gas chromatography-mass spectrometry (GC–MS). The esters exhibited their two characteristically strong absorption bands arising from carbonyl (C O) at 1741 cm−1 of fresh oil, and C O stretching between 1300 and 1000 cm−1 in the FT-IR spectra. A representative spectrum of 13CNMR for the FAME from WCO was confirmed the presence of methyl esters in the biodiesel of ester carbonyl (COO) and C O at 174.2 ppm and 51.4 ppm, respectively. The characteristic peak of 1H NMR at 1.00 ppm of methoxy protons was observed as a singlet at 3.67 ppm, which proved occurrence of the methyl ester (CH 3 COOR). In addition, a significant weight loss at 139 °C was observed through thermogravimetric (TG) analyses of FAME. [ABSTRACT FROM AUTHOR]

Abstract Cardanol was obtained by vacuum distillation of "cashew nut shell liquid" (CNSL). Cardanol is a by-product of cashew production and a building block for chemical synthesis; cardanol and its derivatives can be used for different types of applications. Three of these compounds are the subject of the present NMR study and theoretical comparison. 1H and 13C NMR signals were assigned using 1D and 2D NMR experiments. The DFT/B3LYP method using the cc-pVTZ basis set was employed for the calculations of the 1H and 13C NMR chemical shifts (δ). The obtained data were used as an auxiliary tool for unequivocal assignment of all 1H and 1³C NMR signals. For these compounds, the adopted theoretical model was sufficient to obtain a good description of the chemical shifts. Graphical abstract Cardanol is a by-product of cashew production and a building block for chemical synthesis; cardanol and its derivatives can be used for different types of applications. Three of these compounds are the subject of the present NMR study and theoretical comparison. Image Highlights • Chemical shift calculations using the DFT/B3LYP method. • Complete NMR assignment for three cardanol derivatives. • Experimental and theoretical approach. [ABSTRACT FROM AUTHOR]

Highlights • Pyrolytic profiles from soil organic matter reveal processes related to C cycle. • New surface density plots from compounds atomic ratios depict humic acid structure. • The proportions of common pyrolytic products are correlated with soils properties. • Up to four different non excluding biogeochemical paths define soil C storage. • An empirical model for soil C storage includes the role of agricultural practices. Abstract Molecular assessment of the origin and transformation processes of soil organic matter (SOM) was carried out based on information obtained from 13C NMR and analytical pyrolysis of humic acids (HAs) in soils from wine-growing regions in Tenerife (Canary Islands, Spain). Principal component analysis, using as variables pyrolysis products, shows different soil groups defined by the molecular assemblages released from the corresponding HAs, characterized by the predominance of: i) plant biomacromolecules (lignin) in soils on pumice substrate, ii) heterocyclic N-compounds and methoxyl-lacking aromatic structures, iii) a substantial domain of alkyl compounds in cultivated soils with active C turnover and finally, iv) polysaccharide and protein-derived compounds in soils developed on amorphous gels. The proportions of the pyrolytic compounds from soil HAs were represented by an upgraded graphical-statistical method (3D Van Krevelen plot) that was used to compare the major SOM structural domains in the different soils. The above results coincide with those suggested by the 13C NMR analysis, and were associated to two groups of local land management practices, in terms of their intensity respectively favoring either the transformation of plant-inherited macromolecular precursors from vascular plants, or the humification of aliphatic precursors in the presence of specific mineralogical substrates controlling microbial degradation and humification processes. [ABSTRACT FROM AUTHOR]

Abstract Fossil resin (amber) has been recently reported as common, but small, sedimentary components throughout the lower Upper Cretaceous (Cenomanian; 99–94 Ma) strata of the Tupuangi Formation, Chatham Islands, eastern Zealandia. From these deposits, resin has also been identified and obtained from well-preserved, coalified specimens of the conifer fossil Protodammara reimatamoriori Mays and Cantrill, 2018. Here, we employed attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) to both dispersed and in situ amber specimens. These resulted in very similar chemical signatures, indicating that these fossils are likely from the same or closely-related botanical sources. The FTIR data are typical of a conifer source within the 'cupressaceous resins' category of Tappert et al. (2011). Carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) facilitated the probable identification of these ambers as 'Class Ib' (sensu Anderson et al. 1992). Based on these spectral data sets, the likely botanical sources of the amber were either Araucariaceae or Cupressaceae; both of these conifer families were common and widespread in the Southern Hemisphere during the Cretaceous. However, the morphology and anatomy of P. reimatamoriori support an affinity to the latter family, thus indicating that the Cretaceous amber of the Chatham Islands was generally produced by members of the Cupressaceae. Comparing the FTIR data to the published spectra of modern resins, we also identify a band ratio which may aid in distinguishing between the FTIR spectra of Araucariaceae and Cupressaceae, and outline the limitations to this approach. A high concentration of ester bonds in Chatham amber specimens, which exceeds typical Cupressaceae resins, is probably caused by taphonomic alteration via thermal maturation. The source of thermal alteration was likely pre-burial wildfires, conditions for which P. reimatamoriori was adapted to as part of its life cycle. A comparison of ambers of the Chatham Islands with modern resins and amber from various localities in Australasia reveals that, taphonomic influences aside, Chatham amber has a unique signature, suggesting that members of the basal Cupressaceae (e.g., Protodammara) were not major contributors to other documented Australasian amber deposits. The closest analogy to Chatham amber deposits appears to be the Upper Cretaceous Raritan Formation, USA, which is characterised by its rich amber, charcoal and Cupressaceae fossil assemblages. This study further supports the hypotheses that the early Late Cretaceous south polar forests were dominated by Cupressaceae, and regularly disturbed by wildfires. Graphical abstract Unlabelled Image Highlights • Chatham Islands' Late Cretaceous amber chemically analysed with 13C NMR & ATR-FTIR. • Dispersed amber matches signature of Protodammara reimatamoriori (Cupressaceae). • 13C NMR signature distinct from other Australasian ambers. • New FTIR band ratio helps distinguish Cupressaceae and Araucariaceae resins. • FTIR spectrum indicates thermal maturation; supports wildfire pre-burial heating. [ABSTRACT FROM AUTHOR]

Abstract Kerogen was isolated from the source rock of Well L69, Zhanhua depression, Bohai Bay Basin and an artificial pyrolysis experiment was carried out in a closed gold tube system with a heating rate of 2 °C/h. Products were collected at eleven temperature points every ten degrees from 350 °C to 450 °C. The soluble organic matter and residual kerogens from the experiment were quantified by weighing. Furthermore, the residual kerogens were analysed by element analysis, X-ray photoelectron spectroscopy (XPS) and solid 13C nuclear magnetic resonance (13C NMR) spectroscopy to determine the chemical structural of kerogen during oil generation. Combining the data from the analyses, information on the elemental compositions as well as on how functional groups were connected in residues was obtained. Seven molecular models of initial and residual kerogens were established to trace the structure changes in kerogen with maturity. The results suggest that as the temperature increases, aliphatic chains and small clusters of aromatic groups break down from kerogens, generating soluble hydrocarbons at temperatures of less than 390 °C (Easy% Ro1.15). At higher thermal maturity, a few short aliphatic carbons remain in the structure of residues. The number of aromatic groups increases and their size grows with increasing maturity, with condensation occurring at aromatic groups at high temperature, while these residues have little potential for oil generation. Highlights • Pyrolysis, Element analysis and 13C NMR were performed on kerogen. • Seven kerogen molecular structures with maturity were established. • The calculation method of aromatic cluster size was improved. • The variation in kerogen structures was revealed. [ABSTRACT FROM AUTHOR]

• Complete waste recycling is achieved by botanical concrete. • Mechanism of using kraft lignin (KL) as a reinforcement material is identified. • Alkaline oxidation of KL aided by concrete promotes the condensation of KL. • Low chemical condensation potential of KL should be utilized. Exploring the bonding mechanism of botanical concrete (BC), which is developed by crushing concrete, wood waste and kraft lignin (KL) and hot pressing the obtained powder, aids in comprehending its formation and enhancing performance. This study continues the attempts on this subject, focusing on the microstructural changes between KL and concrete. Herein, the chemical structural transformations in the mixtures of KL with three sources of powder (concrete, carbonated concrete, and sand) during hot pressing are evaluated by FTIR, XRD, TGA, and 13C NMR methodologies. These results show that BC strength is affected by depolymerization, fragmentation, and crosslinking reactions that alter the chemical bonds within KL. Condensation reactions between concrete and KL fragments, facilitated by air, are the most influential factor in improving BC strength. Waste concrete with alkalinity promotes the oxidation of KL and subsequent crosslinking, offering a new perspective for further development of self-bonding lignin-based materials. [ABSTRACT FROM AUTHOR]

• A combination of laboratory experiments and numerical simulations is employed. • The coal macromolecule model before and after NMP treatment was constructed. • NMP can effectively promote the diffusion ability of CH 4 in coal. • The distribution of methane around functional groups was discussed. Chemical stimulation of the coal reservoir is a potential method for enhancing coalbed methane production. N-Methylpyrrolidone (NMP) solvent extraction is a promising chemical stimulation method. To evaluate the effects of NMP treatment on the adsorption and diffusion characteristics of CH 4 in coal, the coal molecular model was established based on elemental analysis analysis, solid-state 13C nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). Then, the adsorption and diffusion characteristics of methane were simulated using Materials Studio software and the distribution of methane molecules around functional groups was studied. The simulation results show that: under the action of NMP solvent, the saturated adsorption capacity of methane molecules was reduced by 41.6%, and the diffusion capacity was increased by 1.72 times. Additionally, methane molecules were mainly enriched around hydroxyl groups and thiophenes, and adding NMP reduced the methane enrichment around functional groups. These show that NMP treatment can promote the diffusion of methane from coal matrix. Hydroxyl and thiophenes affect the diffusion of methane molecules. This study helps to understand the effect of NMP solvent on the adsorption and diffusion mechanism of coal methane from a molecular perspective. [ABSTRACT FROM AUTHOR]

• Field incubation clarified drainage effect on SOM quality in 3 peat forest soils. • C loss after 5 years at depths of 0–20 cm and 60–80 cm was 12–37 % versus 2–31 %. • Decomposition rates of alkyl, O -alkyl, and aromatic C were similar in each soil. • Lignin is also decomposed if groundwater level before drainage is high. • % alkyl C and degree of humification are indicators of the peat SOM decomposability. Tropical peatlands serve as huge carbon (C) pools in the global C balance, and degradation due to agricultural use is a major concern. The objective of the present study was to examine the relationship between the C loss rate in agriculturally drained tropical peat soils in relation to groundwater level (GWL) and the chemical structure of the resulting soil organic matter (SOM). Soil mesocosms containing three peat soils collected from three forest types in Malaysia, Mixed peat swamp (MPS), Alan Batu (ABt), and Alan Bunga (ABg) forests, which are classified based on dominant plant species, species diversity, and forest structure, were buried in an oil palm plantation for a period of five years. Soil samples packed in the top layer (0–20 cm depth) and the bottom (60–80 cm depth) layer were then analyzed and the results were compared with the initial values for these soils. Weight loss, total C and N contents, ash content, and pyrophosphate solubility index (PSI; an index of the degree of humification) were measured. Changes in the chemical structure of the SOC were investigated using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy with phase-adjusted spinning side bands and thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry (THM-GC/MS). The C loss in the MPS forest soil, 2–12%, was smaller than that in the ABt and ABg forest soils, 20–37%, especially in the bottom layer. The higher C loss in the ABt and ABg soils, without significant difference between the top and bottom layers, can be attributed to the greater accumulation of less decomposed plant components as evidenced by the larger yields of lignin-derived phenols and polysaccharide-related compounds in THM-GC/MS analysis. The C composition as estimated by 13C NMR did not vary during incubation of the ABt and ABg soils while the yields of lignin-derived and other phenols as well as polysaccharide-related compounds in THM-GC/MS were decreased, especially in the top layer. These findings suggest that plant components with a low degree of decomposition are susceptible to drainage regardless of their structure. The progression of the oxidative degradation of lignin in the top layer of all soils was also suggested by the increases in PSI and the vanillic acid/vanillin ratio. The % O -alkyl C and % alkyl C may control the rate of C loss positively and negatively, respectively. PSI also appears to be useful for roughly estimating the decomposability of tropical peat SOM in various GWLs. [ABSTRACT FROM AUTHOR]

[Display omitted] • SS 13C NMR is introduced into the research for all coal extraction products. • Carbon skeleton characteristics are quantitatively analyzed for all extraction products. • Influence of particle size on the evolution of coal microstructure during the extraction is focused on. • The work promotes the thorough elucidation on the carbon skeleton structure for all extraction products at a molecular level. To better understand the molecular structure of superfine pulverized coal and promote its practical utilization, the NMR (nuclear magnetic resonance) technology is adopted to study the structural information of all the products from the solvent extraction process, including raw coal, residue, and extract. The whole set of NMR spectra is resolved into different individual curves with specific linewidths, shapes, and intensities. According to the chemical shift, the carbon skeleton characteristics like the aromaticity, cluster size, and other structural lattice parameters are analyzed in detail. More importantly, the influences of coal maturity, coal size, and solvent on the carbon structural evolution during the extraction process are focused on. The results show that the aromatic ring stacking and aromatic ring exposure and fragmentation occur competitively during the superfine comminution, promoting the structural evolution of the coal. In addition, aliphatic carbon transfers more from raw coal into the extract than aromatic carbon in the whole extraction process, which is accompanied by the disappearance of carbonyl groups. Furthermore, the reduction of particle size can promote the extraction effect of the extractant on the coal powder, and reduce the proportion of aliphatic carbon in the residue. The work introduces the correlations among the raw coal, residue and extract from a carbon skeleton point of view, providing a reference for elucidating the solvent extraction mechanisms. The results shed light on better understanding the coal structure and its further molecular modeling. [ABSTRACT FROM AUTHOR]

• DFT calculations of NMR parameters for model compounds were performed. • Selected methods served to estimate the NMR parameters for 3-fluoroprop-2-enoic acid. • Non-covalent interactions of F...H and O...F occur in (2Z) 3-fluoroprop-2-enoic acids. • 3-fluoroprop-2-enoic acids tend to form dimers and trimers in solution. Nuclear magnetic resonance (NMR) parameters, shielding constants, and indirect spin-spin coupling constants (SSCC) in a large set of model compounds were calculated using the combination of the B3PW91, B3LYP, and BHandH functionals with the 6-311+(d,p), 6-311++G(d,p), 6-311++G(2d,p), and 6-311++G(3df, 3pd) basis sets, in order to verify the most appropriate methods for calculating these parameters. Selected methods were applied to calculate the NMR parameters in (2E)- and (2Z)-3-fluoroprop-2-enoic acids. Optimization of structures revealed four stable rotamers of each isomer, E and Z , of 3-fluoroprop-2-enoic acid. The internal molecular energy of s-cis and s-trans syn rotamers indicated that they are favorable in solution. All rotamers of 3-fluoroprop-2-enoic acid are coplanar except E s-trans anti , which has a "twisted" structure due to repulsion between hydrogen atoms CFH and HO. Topological analysis of the electronic structure of molecules including properties of critical points revealed noncovalent F...OH and F...HO bonds in Z s-trans syn and anti rotamers, respectively. The molecules of acid tend to form dimers and trimers in solution via hydrogen bonds O...H, CH...O, and CH...F, with binding energies ranging from a few to over a dozen kcal per mol. Theoretical chemical shifts and SSCCs were analyzed in detail to find a dependence on the geometry of individual rotameters. Calculations revealed a 5 J (F,H) of -31 Hz in Z s-trans-anti rotamer containing the F...HO hydrogen bond, while this SSCC ranges from -1.9 to 1.4 Hz in the remaining rotamers. Intermolecular SSCCs across hydrogen bonds range from -3 to 7 Hz in dimers and trimers. Theoretical NMR parameters were compared with available experimental data. [Display omitted] [ABSTRACT FROM AUTHOR]

The amounts (N B,t) and rates of bond cleavage of coal are essential for the development and optimization of pyrolysis and direct liquefaction processes. A hybrid first order kinetics model is developed in this work to suit the complex and diverse properties of covalent bonds in coal, and the N B,t of four low rank coals at 380–440 °C are fitted to determine the kinetics parameters. In specific, the hybrid model includes the single-temperature linear regression (STLR) and the multi-temperature nonlinear regression (MTNLR). The STLR method yields the maximum amounts of cleavable bonds N B,0 at different temperatures, which are then incorporated into the MTNLR model to yield the kinetics parameters, E a and A. The hybrid model significantly improves the fitting accuracy in comparison with the single STLR or MTNLR model. The ln A∼ E a relations in the three models for four coals' bond cleavage kinetics follow a similar compensation effect but differ from those for the mass change kinetics. • A hybrid kinetics model is developed to better fit the bond cleavage of coal. • The differences of bond cleavage rate between coals are mainly in the first 3 min. • The maximum amount of cleavable bonds of coal increases linearly with temperature. • E a of bond cleavage, 13.3–36.1 kJ/mol, is correlated well with the C al -C al number. • Kinetics compensation effect for bond cleavage differs from that for mass change. [ABSTRACT FROM AUTHOR]

Understanding the molecular structure characteristics of coal from the molecular level is of great significance for realizing rational utilization and efficient transformation of coal. The molecular structure of coal samples from 1304 working face in No.13 coal seam of Hongyang No.2 Mine (HY) was studied by industrial analysis, elemental analysis, Nuclear magnetic resonance carbon spectroscopy (13C NMR) and Fourier transform infrared spectroscopy (FTIR). The results show that the aromatic compounds in coal samples of HY are mainly naphthalene ring structures. The aliphatic structure mainly consists of methyl, ethyl side chains and cycloalkanes. The ratio of aromatic bridge carbon to weekly carbon in molecular structure is 0.17. Oxygen atoms exist in the form of carbonyl, hydroxyl, and ether bonds, nitrogen atoms exist in the form of pyridine and pyrrole respectively, and sulfur atoms exist in the form of thiophene. Based on this, the planar structure model of coal macromolecule in HY is constructed, and its molecular formula is C 129 H 88 O 29 N 2 S, and its molecular weight is 2160. The structure optimization and annealing kinetics simulation of a single macromolecule model were carried out, and a stable three-dimensional coal model of HY was obtained. In addition, the oxygen absorption characteristics of coal samples in HY were studied by molecular dynamics and quantum chemistry. The results show that the adsorption capacity of the Wiser model is less than that of HY coal model. This is because, compared with the Wiser model, the content of oxygenated aliphatic hydrocarbons in the molecular structure of HY coal is higher, and the condensation degree of polycyclic aromatic hydrocarbons is lower. Due to the stronger physical adsorption capacity of hydroxyl, ether bond, and carbonyl on O 2 , HY Mine has stronger physical adsorption capacity on O 2. [ABSTRACT FROM AUTHOR]