Mechanism Of Chemical Transformations Research Articles

Effective elimination of internal phosphorus pollution with MgFe-LDHs hybrid material in eutrophic water: The chemical forms, transformation mechanism, and dynamic relationships

The internal phosphorus (P) pollution is a major cause of water eutrophication. Although the traditional powders materials, with good performance, were difficult to recycle due to its shape, and the reaction mechanism between materials and internal P was rarely elucidated. In this work, a hydrotalcite composite material (MgFe-LDHs hybrid gel microspheres) was prepared via chemical crosslinking to eliminate internal P pollution both in overlying water and sediments effectively. Benefiting from the strong coordination between iron hydroxide on the MgFe-LDHs surface and internal P, the P adsorption capacity was up to 1256.38 mg/kg under natural conditions, the IP (NaOH-P and HCl-P) and OP were 78 % and 22 %, respectively. During 40-days remediation experiment, with the addition of MgFe-LDHs hybrid gel microspheres, whatever in the mixed or the capped, promoted a conversion from stable P to soluble active P of NaOH-P in sediments, and thus contributing to an easy adsorption of NaOH-P by MgFe-LDHs hybrid gel microspheres (The NaOH-P in sediments decreased by 16 % and 22 %, respectively). Meanwhile, the excessive stable HCl-P (only a minor portion) that could not be adsorbed by MgFe-LDHs remained in the form of Ca-P in sediments. Additionally, the MgFe-LDHs hybrid gel microspheres improved the microbial community structure, and the microorganism was involved in the elimination of internal P simultaneously. In summary, this study proposed a promising remediation approach to resolve the problem of internal P pollution in eutrophic water with high efficiency, cost-effective, and environmentally friendly.

Exploration on the mechanism of “black as lacquer and sweetness as candy” based on the reactions of “crosslinking coloring and Maillard” and “oligosaccharide hydrolysis” during the processing of Radix Rehmanniae

Radix Rehmanniae (RR) has three processing forms in clinical practice, including fresh Radix Rehmanniae (FRR), raw Radix Rehmanniae (RRR), and processed Radix Rehmanniae (PRR). However, the sensory criterion, “black as lacquer and sweetness as candy”, which was traditionally used to evaluate the quality of PRR, have not been fully elucidated. In this study, the mechanism of chemical transformation based on oligosaccharide hydrolysis, crosslinking coloring, and Maillard reactions was explored to clarify the observed changes in appearance and flavor. The physicochemical properties of different processed RR products were characterized. Besides, “sweetness as candy” was explained by oligosaccharides hydrolysis, and “black as lacquer” can attribute to crosslinking coloring and Maillard reactions. Importantly, this study provided the first evidence for the existence of crosslinking coloring reaction during the processing of RR. In conclusion, our results unveiled the scientific basis of the sensory attributes “black as lacquer and sweetness as candy” in PRR, offering valuable insights for enhancing quality control of PRR.

Oxygen-Isotope Exchange between CO2 and NO2 with Implications for Atmospheric Chemistry.

Elucidating isotope exchange between atmospheric trace molecular species is important for environment monitoring, climate control studies, and a fundamental understanding of atmospheric chemistry. Here, we provide direct experimental evidence of oxygen-isotopic exchange between carbon dioxide (CO2) and nitrogen dioxide (NO2), which are simultaneously emitted into the atmosphere from common sources. A combined near-infrared and UV-vis optical cavity-enhanced experimental investigation along with quantum-chemical calculations followed by a reaction modeling study revealed that CO2 and NO2 can communicate isotopically by near-ultraviolet-driven NO2 photolysis. Our results found evidence for a near-barrierless (1.67 kcal/mol) nitrate-containing complex having a very short lifetime (∼13 ns) which facilitates the transfer of 18O-isotopes from 18O12C16O to N16O16O, leading to isotopic depletion of 18O in 18O12C16O, thus opening a new gas-phase isotope-selective chemical transformation mechanism in the lower atmosphere. This isotope exchange study may serve as a new window into the fundamental understanding of isotopic photochemistry, oxygen isotopic fractionations, and climate modeling.

Chemical transformation mechanism for blue-to-green emitting CsPbBr3 nanocrystals.

Recently, metal-halide perovskites have rapidly emerged as efficient light emitters with near-unity quantum yield and size-dependent optical and electronic properties, which have attracted considerable attention from researchers. However, the ultrafast nucleation rate of ionic perovskite counterparts severely limits the in-depth exploration of the growth mechanism of colloidal nanocrystals (NCs). Herein, we used an inorganic ligand nitrosonium tetrafluoroborate (NOBF4) to trigger a slow post-synthesis transformation process, converting non-luminescent Cs4PbBr6 NCs into bright green luminescent CsPbBr3 NCs to elucidate the concrete transformation mechanism via four stages: (i) the dissociation of pristine NCs, (ii) the formation of Pb-Br intermediates, (iii) low-dimensional nanoplatelets (NPLs) and (iv) cubic CsPbBr3 NCs, corresponding to the blue-to-green emission process. The desorption and reorganization of organic ligands induced by NO+ and the involvement of BF4- in the ligand exchange process played pivotal roles in this dissolution-recrystallization of NCs. Moreover, controlled shape evolution from anisotropic NPLs to NCs was investigated through variations in the amount of NOBF4. This further validates that additives exert a decisive role in the symmetry and growth of nanostructured perovskite crystals during phase transition based on the ligand-exchange mechanism. This finding serves as a source of inspiration for the synthesis of highly luminescent CsPbBr3 NCs, providing valuable insights into the chemical mechanism in post-synthesis transformation.

Chemical change and mechanism of Millettia speciosa with sulfur fumigation by UHPLC–QTOF–MS/MS

Millettia speciosa Champ. (MSCP), which is distributed and used in Southern China, is often sulfur-fumigated during postharvest handling to prevent insects and molds. In the present study, a comprehensive strategy was proposed by using ultrahigh-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UHPLC–QTOF–MS/MS) with multivariate analysis to rapidly identify potential chemical sulfur-fumigated MSCP (SF-MSCP) samples, discover chemical transformation mechanisms and control the quality of SF-MSCP. Eighty-six compounds were tentatively assigned, and ten compounds were screened out as potential markers. Moreover, the chemical transformation mechanism was deduced by hydrolysis, esterification and dehydration reactions that occurred during the sulfur-fumigated process. The developed method was successfully applied to predict 16 commercial MSCP samples, and 9 samples were found to contain sulfur compounds, ranging in sulfur residues from 100 to 310 mg/kg. These research outcomes can not only be used to distinguish the nonfumigated MSCP from SF-MSCP by chemical markers but also provide a chemical basis for further comprehensive investigating in-depth safety and functional evaluations of SF-MSCP.

Chemical reaction and phase transformation mechanism of electrospun iron (III) acetylacetonate-polyacrylonitrile fibers during pre-oxidation process

Low-temperature pre-oxidation of electrospun metal-compound-incorporated carbon fibers can involve phase transitions and chemical reactions. However, their mechanics remain unclear. In this work, a mixture of polyacrylonitrile (PAN) and iron acetylacetonate is subjected to electrospinning followed by a pre-oxidation process at 230 °C, producing PAN fibers loaded with iron compounds. Our detailed investigations shed light on the mechanisms of phase transitions and associated chemical reactions during the pre-oxidation process. Our findings reveal that PAN undergoes cyclization during pre-oxidation, and that crystalline iron acetylacetonate within PAN fibers transforms into amorphous FeO and Fe2O3.

Evaluation of raw and processed Phellodendri Chinensis Cortex using the quality marker analysis strategy by UHPLC-Q-Orbitrap MS and multivariate statistical analysis.

Introduction: Phellodendri Chinensis Cortex is a necessary part of healthcare for its significant clinical efficacy. Raw and processed Phellodendri Chinensis Cortex is both documented in the Chinese Pharmacopoeia (2015). After processing, the therapeutic effects are believed to differ according to traditional Chinese medicine theories. However, the chemical mechanism responsible for this processing, according to traditional Chinese medicine theories, is still not clear. Methods: In this study, the therapeutic effects of various ions were examined based on traditional Chinese medicine theories by ultra-high performance liquid chromatography-hybrid quadrupole-Orbitrap mass spectrometry (UHPLC-Q-Orbitrap MS) coupled with multivariate statistical analysis, such as principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), to comprehensively compare the differences between raw and processed Phellodendri Chinensis Cortex for the first time. Results: A total of 48 compounds were screened, out and 10 of them simultaneously transformed with significant variation in processed products compared with raw materials. It was illustrated that the contents of berberine, palmatine, jatrorrhizine, magnoflorine, menisperine, phellodendrine, tetrahydrojatrorrhizine, and tetrahydropalmatine decreased, while the compounds of berberrubine and fernloylquinic acid methyl ester newly appeared in processed herbs. This is likely to be related to the conversion of ingredients during processing. Discussion: Altogether, the fact that quality markers have been successfully identified to differentiate processed Phellodendri Chinensis Cortex from raw materials suggests that this approach could be used for the investigation of chemical transformation mechanisms involved in the processing of herbal medicine.

Emission Characteristics, Speciation, and Potential Environmental Risks of Heavy Metals from Coal-Fired Boilers: A Review

Coal-fired boilers, including coal-fired power plants (CFPPs) and coal-fired industrial boilers (CFIBs), are an important area for achieving sustainability globally as they are one of the globally important sources of anthropogenic emissions of heavy metals (HMs) due to huge amount of coal consumption. To date, the investigation of atmospheric emission characteristics, speciation, and potential environmental risks of HMs from coal-fired boilers has received widespread attention and achieved significant progress. To characterise the emissions of HMs from coal-fired boilers, research is currently being carried out in the areas of (1) studying the release of HMs from coal combustion processes, (2) developing emission factors and emission inventories, and (3) revealing the cross-media partitioning of HMs between different output streams. Research on the chemical forms of HMs in waste from coal-fired boiler is currently focused on chemical valence and speciation components. The sequential chemical extraction method is currently the most widely used method for investigating the chemical fractionations of HMs in wastes from coal-fired boilers. Studies indicate that different HM elements display differentiated characteristics of speciation in waste from coal-fired boilers. Early studies on potential environmental risk and ecological risk caused by HMs are usually based on actual monitoring values of HMs in the target environmental media. The risk assessment code method and the leaching toxicity method are the most widely used method to study the potential environmental risk of HMs in waste from coal-fired boilers. With the implementation of global carbon emission reduction strategies, the scale of coal-fired boilers and air pollution control technologies are bound to change in the future. Therefore, as an important component of global efforts to achieve sustainable development, more research is needed in the future to improve the accuracy of emission inventories, reveal the mechanisms of HM chemical transformation, and establish methods for potential environmental risk assessment at regional scales.

Global distribution, toxicity to humans and animals, biodegradation, and nutritional mitigation of deoxynivalenol: A review.

Deoxynivalenol (DON) is one of the main types of B trichothecenes, and it causes health-related issues in humans and animals and imposes considerable challenges to food and feed safety globally each year. This review investigates the global hazards of DON, describes the occurrence of DON in food and feed in different countries, and systematically uncovers the mechanisms of the various toxic effects of DON. For DON pollution, many treatments have been reported on the degradation of DON, and each of the treatments has different degradation efficacies and degrades DON by a distinct mechanism. These treatments include physical, chemical, and biological methods and mitigation strategies. Biodegradation methods include microorganisms, enzymes, and biological antifungal agents, which are of great research significance in food processing because of their high efficiency, low environmental hazards, and drug resistance. And we also reviewed the mechanisms of biodegradation methods of DON, the adsorption and antagonism effects of microorganisms, and the different chemical transformation mechanisms of enzymes. Moreover, nutritional mitigation including common nutrients (amino acids, fatty acids, vitamins, and microelements) and plant extracts was discussed in this review, and the mitigation mechanism of DON toxicity was elaborated from the biochemical point of view. These findings help explore various approaches to achieve the best efficiency and applicability, overcome DON pollution worldwide, ensure the sustainability and safety of food processing, and explore potential therapeutic options with the ability to reduce the deleterious effects of DON in humans and animals.

Simulated processing with vinegar changes chemical structures of main terpenoids in Euphorbiae Ebracteolatae Radix

This study aims to explore the chemical structure transformation mechanisms of the main terpenoids in the effective fraction of Euphorbiae Ebracteolatae Radix(EER) during the processing with vinegar. The terpenoids including ent-11α-hydroxyabicta-8(14),13(15)-dien-16,12-olide(HAO), jolkinolide B(JNB), fischeria A(FA), and eupractenoid A(EA) were heated at 160 ℃ with 6% acetic acid for 40 min, and then LC-MS/MS was employed to analyze the structural transformation rules of the terpenoids. Further, we analyzed the changes in the relative content of the four compounds and their transformation products in raw and vinegar processed EER to verify the transformation rules during the simulated processing with vinegar. In addition, JNB and FA were processed with single heating, heating with water or heating with acetic acid. We then employed HPLC to compare the content of these two terpenoids and their transformation products before and after processing, so as to investigate the effect of different processing methods on chemical structure transformation. The results showed that the lactone ring of the abietane-type diterpenoids HAO and JNB and the norditerpene lactone FA were opened by heating with acetic acid. When there were hydroxyl groups in the structures, terpenoids were esterized to esters and oxidized to form carbonyl groups. When there was epoxy ring in the structures, ring opening reaction was easy to occur. During the heating with acetic acid, the heterodimeric diterpenoid EA underwent the cleavage of ether bond to produce the rosane-type diterpenoid euphebracteolatin A(EHTA) and another abietane-type diterpenoid. The changes in the relative content of terpenoids and their transformation products in raw and vinegar-processed EER were basically consistent with those of simulated processing of components with vinegar. The HPLC results revealed that the effect of different simulated processing methods on structural transformation varied. Heating with acid can change JNB and FA into new components. Heating with water can also promote the structural transformation, with the efficiency obviously lower than that of heating with acid. Direct heating had no influence on the structure of JNB, while it significantly reduced the relative content of FA. The components treated with direct heating did not produce the products like those of the heating with acid. These results indicated that vinegar plays a key role in the structural transformation of diterpenoids during the processing of EER with vinegar. The structural transformation of diterpenoids in EER during the processing with vinegar may be the material basis for vinegar processed EER to reduce toxicity and preserve effect.

Maize-soybean intercropping facilitates chemical and microbial transformations of phosphorus fractions in a calcareous soil.

Intercropping often substantially increases phosphorus (P) availability to plants compared with monocropping, which could be an effective strategy for soil legacy P recovery and agricultural production. However, the biogeochemical interactions among plants, microbes, and soil that mobilize P remain largely unknown in intercropping systems. Pot experiments with maize-soybean intercropping in a calcareous soil were conducted to investigate the potential chemical and biological transformation mechanisms of inorganic P (Pi) and organic P (Po) using sequential extraction and Illumina MiSeq sequencing. Compared to monocropping of each crop, maize-soybean intercropping significantly enhanced total P uptake of the two crops by mobilizing Ca2-Pi [extracted by bicarbonate (NaHCO3)], Al-Pi/Po [extracted by ammonium fluoride (NH4F)] and Fe-Pi [extracted by sodium hydroxide and sodium carbonate (NaOH-Na2CO3)] fractions. Furthermore, there were significant increases in the organic carbon content and alkaline phosphomonoesterase (ALP) and phosphodiesterase (PDE) activities as well as the abundances of Microvirga, Lysobacter, Microlunatus and Sphingomonas under maize-soybean intercropping relative to monocropping. In contrast, compared to monocroppping, no significant change in the soil pH was observed under maize-soybean intercropping. Therefore, the enhanced P uptake of the maize-soybean intercropping probably resulted from a synergistic effect of rhizosphere organic carbon deposit, increased activities of ALP and PDE, together with the bacteria (Microvirga, Lysobacter, Microlunatus and Sphingomonas) which showed correlation with soil P forms, while the generally recognized rhizosphere acidification was excluded in this investigated calcareous soil. Moreover, the selected bacterial genera exhibited a closer network in the rhizosphere of soybean compared to maize, suggesting enhanced interactions among bacteria in the soybean rhizosphere. These results provide theoretical bases for the recovery of soil legacy P by maize-soybean intercropping.

Regioselective Plasmon-Driven Decarboxylation of Mercaptobenzoic Acids Triggered by Distinct Reactive Oxygen Species

The non-radiative decay of surface plasmon resonance (SPR) in plasmonic metal nanoparticles (NPs) opens up unique hot-carrier-driven chemical transformation mechanisms. Here, the hot-carrier generation of reactive oxygen species was demonstrated to trigger the regioselective plasmon-driven decarboxylation of mercaptobenzoic acid (MBA) isomers over Ag (AgNPs) and Au nanoparticles (AuNPs). Controlled catalytic experiments indicated that the catalytic C–C bond cleavage over AgNPs and AuNPs is primarily initiated by photogenerated singlet oxygen (1O2) and hydroxyl radical (•OH), respectively. Energetic hot electrons on AgNPs can successfully generate 1O2 from 3O2 via Dexter energy transfer, while hot holes generated under the Fermi level of AuNPs have sufficient energy to oxidize OH– and promote the formation of reactive •OH. The catalytic activity trend was evaluated considering the known ortho-substituent effect. The data discussed herein shed light on how the intrinsic differences in electronic energy levels and metal–molecule interactions precisely tune the regioselectivity of plasmon-driven transformations and may guide the rational design of plasmonic catalysts for distinct desired reactions.

Formation mechanisms of Wuboraite (CaAl2Cr2O7) in air and Ar atmosphere

Recently, a new high-temperature ternary Cr(III) phase (Wuboraite, CaAl2Cr2IIIO7) was synthesized in the Al2O3–CaO–Cr2O3 system. However, its formation & chemical transformation mechanism is yet to be explored in detail. And here, we investigated the system between 500 and 1600 °C under the air and argon (Ar) atmosphere via solid-state reaction using XRD, TG-DSC, XPS, and leaching tests. Wuboraite formation starts at different temperatures (∼1500 & ∼1100 °C) under different atmospheres (air and Ar). The intermediate compounds, CaCrVIO4 and CaCr2IIIO4, formed under air and Ar atmospheres, play a crucial role in wuboraite conversion given proper temperature and stoichiometry.

Study on the processing chemistry of Fructus Psoraleae by a combination of untargeted and targeted metabolomics.

Fructus Psoralea is widely used to treat osteoporosis and skin inflammatory diseases. Because of the side effects on the liver, renal and cardiovascular systems, it is processed to salt-processed Fructus Psoraleae to meet the requirements of clinical use. However, the mechanisms involved in the transformation of the chemical components are unclear. In this study, ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry was used to analyze the chemical profiles of this herbal medicine and the chemical transformation mechanism involved during the salt processing was studied. A total of 83 compounds were identified. Principal component analysis and orthogonal partial least squares discriminate analysis were used to observe the distribution trend of all samples and visualize the difference. Raw and processed Fructus Psoraleae were clearly clustered into two groups. Furthermore, 17 marker compounds were identified as primary contributors to their differences based on t-test analysis (p <0.01) and orthogonal partial least squares discriminate analysis (variable importance for the projection>1). Finally, ultra-high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry was used to evaluate the quality of Fructus Psoraleae by simultaneous analysis of 13 components highly related to efficacy. There were variations in the contents of 13 chemicals of Fructus Psoraleae and salt-processed products. The results of untargeted and targeted metabolomics revealed that salt processing affected the chemical composition of Fructus Psoraleae.

First-principles investigation of interaction between the atomic oxygen species and carbon nanostructures

• The following trends in the value of adsorption energies of triplet oxygen atoms on the carbon nanostructures were identified: diamond-like structures (sp 3 ) < graphene-like structures (sp 2 ) < fullerenes & nanotubes (sp 2 , pentagons, high curvature). • For the graphene flake and fullerene structures there are common precursors for carbon desorption in the form of CO/CO 2 molecules: (1) ether-ether-epoxy precursor and (2) epoxy-ether-epoxy. • Etching of sp 3 hybridized carbon structures can proceed faster than etching of sp 2 structures. • For graphene structure, unzipping process is more favorable than reduction process at lower temperatures. In this work we perform a systematic theoretical study of oxidation process of different carbon nanomaterials by atomic oxygen. In order to understand the atomistic mechanism of interaction between atomic oxygen and carbon nanostructures and to explain experimental results on their oxygen treatment, first-principles calculations were performed. Influence of spin state of the atomic oxygen on its interaction with different carbon nanostructures (finite size graphene flake, carbon nanotube, fullerene, diamondoid) was investigated. We found that the structure and stability of the adsorption complexes are determined by the oxygen spin state and depend on the carbon nanostructure morphology and hybridization. The atomistic mechanisms of chemical transformations driven by high local oxygen coverage, such as CO/CO 2 desorption and graphene unzipping, were investigated. Calculated barriers of CO 2 desorption allow to explain experimental data on thermal reduction of the oxidized carbon structures. In case of graphene, competition between channels resulting in CO 2 desorption and plane unzipping was observed. We found that for the temperatures ~400 K and lower unzipping process is favorable, since CO 2 desorption precursor formation proceeds through higher activation barrier (1.3 eV) and requires temperatures above 450 K.

Mechanochemical Transformations of Polysaccharides: A Systematic Review.

Taking into consideration the items of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this study reviews application of mechanochemical approaches to the modification of polysaccharides. The ability to avoid toxic solvents, initiators, or catalysts during processes is an important characteristic of the considered approach and is in line with current trends in the world. The mechanisms of chemical transformations in solid reactive systems during mechanical activation, the structure and physicochemical properties of the obtained products, their ability to dissolve and swell in different media, to form films and fibers, to self-organize in solution and stabilize nanodispersed inorganic particles and biologically active substances are considered using a number of polysaccharides and their derivatives as examples.

Excited state modulation of C70 dimerization in a carbon nanotube under a variable electron acceleration voltage

Cinematographic recording of chemical reactions with transmission electron microscopy provides information unavailable by any other analytical methods. Studies have thus far remained mostly phenomenological, lacking information on the reactive species involved. To gain insight into the nature of the reactive species, we need to obtain kinetic information under various temperatures and variable acceleration voltages, i.e., electronic energy supply. We studied the mechanism of [2 + 2] dimerization of [70] fullerene in a carbon nanotube as an example. We describe herein a statistical analysis of individual reaction events of the dimerization that revealed dose-dependent first-order kinetics and voltage-dependent crossover from a singlet to a triplet mechanism, as highlighted by the pre-exponential factor (the frequency of excitation) that is a million times larger for the singlet reaction than for the triplet one. Comparison with the results of a recent study of [60] fullerene dimerization lets us propose that electron-impact excitation of the carbon nanotube is the first step, followed by energy transfer to fullerene molecules and their dimerization via an excited state. The results show that a variable-voltage kinetic study is indispensable for discussing the mechanism of chemical transformations under electron microscopic observation.

PH-Dependent Chemical Transformations of Humic-Like Substances and Further Cognitions Revealed by Optical Methods.

Humic-like substances (HULIS) are macromolecular complex groups in water-soluble organic compounds (WSOC). pH is a crucial factor that influences the chemical transformations of HULIS in atmospheric particles, but this has been rarely investigated, especially under varying pH conditions. This study attempted to unveil the chemical transformation mechanisms of HULIS under a range of pH conditions using optical methods. The pH-dependent light absorption and fluorescence properties of HULIS were comprehensively analyzed; the acidity coefficient (pKa) of HULIS in relation to chemical structures was determined, and the hypothetical chemical transformation mechanisms of HULIS with increasing pH were analyzed by optical characterizations. The results suggested that pH greatly impacted the light absorption and fluorescence efficiencies of HULIS in both winter and summer seasons, and pKa was an important inflection point. The pKa of HULIS ranged from 3.5 to 8.0 in winter and 6.4 to 10.0 in summer. The acidic/basic groups were identified as -OH or -NH2 substituted quinolines, carboxylic aromatics, and pyridines. The pH-sensitive species accounted for about 6% and 21% of HULIS-C (carbon concentrations of HULIS) in winter and summer, respectively. The varying optical spectra with increasing pH might result from charge transfer or complex reactions with HULIS deprotonation.

RRLC-QTOF/MS-Based Metabolomics Reveal the Mechanism of Chemical Variations and Transformations of Astragali Radix as a Result of the Roasting Process.

Astragali Radix (AR), which is extensively used as a healthy food supplement and medicinal herb, contains two forms of products corresponding to raw Astragalus Radix (RAR) and processed Astragali Radix (PAR), which was obtained by roasting. In this study, a non-targeted rapid resolution liquid chromatography coupled with quadruple time-of-flight mass spectrometry (RRLC-Q/TOF-MS) based metabolomics approach was developed to investigate the chemical changes of AR due to roasting. A total of 63 compounds were identified or tentatively identified. Among them, 23 isoflavonoids (composed of 12 isoflavones, eight pterocarpans, and three isoflavans) and six cycloastragenols were characterized as differential metabolites. Heatmap visualization and high-performance liquid chromatography coupled with photodiode array and evaporative light scattering detector (HPLC–PDA-ELSD) quantitative analysis revealed that malonyl isoflavonoids or cycloastragenols were at higher levels in RAR. These might be converted to corresponding acetyl isoflavonoids and cycloastragenols and related isoflavonoid glycosides during roasting. To prove this prediction, chemical conversion experiments on malonyl isoflavonoids and cycloastragenols were performed to confirm and clarify the chemical transformation mechanism.

&lt;i&gt;In situ&lt;/i&gt; study of heterogeneous media combustion processes by time Resolved XRD

The use of in situ diagnostic methods is required to obtain data on the structure and composition of the material in real time when studying condensed substances in the course of chemical reactions and phase transformations. We present the results on the development and application of the time-resolved X-ray diffraction method for the diagnosis of fast processes in heterogeneous condensed media, including self-propagating high-temperature synthesis. An X-ray tube was used as a radiation source. The method is based on the use of high-speed registration of XRD patterns in a wide angular interval and provides obtaining in situ data on the evolution of the crystal structure of the reactants. A high-speed linear detector and reaction chambers, an effective analysis system with a time resolution in the range of 10–1 – 102 sec has been developed on the base of a powder diffractometer. A complex of object-oriented diffraction techniques has been developed to study the dynamics of phase transitions in self-propagating high-temperature synthesis of inorganic materials, combustion of energy systems and liquid solutions, crystallization of amorphous alloys, in the analysis of the phase composition of materials in the process of heat treatment. The results obtained can be used to identify the mechanism of structural and chemical transformations in condensed matter.