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Varying proportions of H2O-CO2 atmospheres were introduced into the softening-melting-dripping detector to reduce iron ores under a high-temperature load after applying lump ores to a hydrogen-rich blast furnace. Research was carried out on the metallurgical properties of lump ores and the deterioration behavior of cokes. The primary findings were as follows. The softening rate of lump ores increased and dripping temperature decreased under an H2O-containing atmosphere compared to a CO2 atmosphere, with significant amounts of Fe2SiO4 and FeO in droplets. Moreover, the softening temperature of lump ores decreased while the melting temperature increased with the increased H2O content. Consequently, the permeability of material columns and the liquid permeability of coke layers improved. The optimal permeability of material columns was observed at 18.75 pct H2O content, although the Fe content in reduction products was the lowest. Increasing the H2O content led to more surface reactions on cokes and greater difficulties in separating ores from cokes; however, it slowed the reduction in coke strength. Additionally, H2O was found to have a weaker effect on coke graphitization compared to CO2. [ABSTRACT FROM AUTHOR]

Due to the varying connectivity of Zr6 cluster and unlimited carboxylic acid‐based organic linkers, zirconium‐based metal‐organic frameworks (Zr‐MOFs) exhibit the most abundant structural diversity. However, Zr‐MOFs possessing more than one kind of Zr6 clusters in a single structure have not yet been reported. Herein, four new pentacarboxylic acids are synthesized to prepare Zr‐MOFs, HIAM‐4051 to HIAM‐4054. As a result, due to the different lengths of linkers, two novel underlying nets (typ and cqh) are found in these four MOFs with coexisting 4‐ and 9‐connected Zr6 clusters. Furthermore, by changing the acceptor groups in the linker skeleton, the emission of results Zr‐MOFs can be customized from blue, yellow–green to red. The nano‐sized HIAM‐4053‐NS exhibits high sensitivity and efficient adsorption for tetracycline hydrochloride with 0.22 µm detection limit and ≈0.6 g g−1 removal capacity. To the best of the knowledge, this work is the first example of constructing Zr‐MOFs using pentacarboxylic acids as organic linkers and the first report of Zr‐MOFs with coexisted Zr6 connectivities in a single MOF matrix. This study provides a novel insight for the construction of Zr‐MOFs with unprecedented structures, which will not only enrich the structure diversity but also offer more opportunity to extend the applications of Zr‐MOFs. [ABSTRACT FROM AUTHOR]

Nano‐thermite has become a subject of significant interest in the composite energetic materials field due to its high energy release rate. To cater to diverse engineering needs, thermite formulations are often customized to fulfill specific criteria. This study investigates the potential of metal nickel (Ni) as an additive to modify nano‐thermite formulations, selected for its optimal calorific values and chemical reactivity. The base materials, nano‐aluminum (Al) and iron oxide (Fe2O3), are blended with varying mass ratios of Ni (1 %, 3 %, 5 %, 7 %, 9 %) using the wet ball milling method. Pre‐reaction and post‐reaction morphological and compositional alterations in the resultant thermite samples are scrutinized through SEM and XRD characterization tests. Moreover, DSC analysis and combustion experiments were conducted to examine the pyrolysis and combustion behaviors of the evaluated samples. The results reveal a reduced exothermic peak on the DSC curves with the introduction of Ni, making the liquid‐solid (L‐S) phase reaction more challenging compared to the Al/Fe2O3 thermite. Intriguingly, Ni addition progressively decreases the combustion temperature of thermites as the Ni's mass ratio increases, with a peak efficiency at 7 % in the perforation tests on stainless‐steel plates. This research further reveals that the thermite reaction mechanism is a combined consequence of the "pre‐ignition‐fusion" and "fusion‐diffusion" mechanisms. These insights can provide valuable guidance for designing thermite formulations for potential applications in storage, management, and pyrotechnic cutting areas. [ABSTRACT FROM AUTHOR]

A high-temperature gas-solid reaction device was used to simulate the gasification of coke in a hydrogen-rich blast furnace, with the gasification reaction of water/anhydrous bulk cokes studied. CO2 and H2O effects on coke gasification kinetics were analyzed in CO2-N2-H2O and CO2-N2 with the experimental temperature of 1173–1523 K, the CO2 content of 15–60%, and the H2O content of 15%. Compared with those of CO2-N2, the gasification reaction rate and carbon conversion rate of cokes in the CO2-N2-H2O mixture were significantly higher. Carbon conversion rates of the CO2-N2-H2O mixture at different temperatures were about 30% higher than those of CO2-N2 on average, and the gasification reaction rate was about 50% higher on average. There were two temperature regions for gasifying cokes in CO2-N2-H2O and CO2-N2 mixtures. At 1,273 K, the gasification reaction is transformed into diffusion control, which is from chemical reaction control. The aggravation of coke gasification by H2O generated after hydrogen reduction of iron ores was mainly reflected at the lower temperature. Besides, the kinetic model analysis showed that random pore model was optimal in describing the gasification reaction of cokes in CO2-N2-H2O and CO2-N2, and the addition of H2O improved the gasification reaction's activation energy. [ABSTRACT FROM AUTHOR]

The volume‐fraction changes of CO2 and H2O after adding different proportions of H2 to the hydrogen‐rich blast furnace were simulated by thermodynamic calculations to evaluate the effects of H2 on coke gasification in a blast furnace. Thermodynamic calculations indicated that the H2O content in the mixed gas gradually increased with higher H2 content. The coke gasification kinetics effective diffusion coefficient De and interfacial reaction rate constant k+ of the coke gasification reaction improved with higher H2 content. In addition, the reactivity of cokes enhanced and the coke strength after reaction decreased with higher H2 content. Mercury porosimeter experiments demonstrated that the coke gasification reaction mainly occurred on the surface. [ABSTRACT FROM AUTHOR]

Hydroxyl radical-mediated protein footprinting is a convenient and sensitive technique for mapping solvent-accessible surfaces of proteins and examining the structure and dynamics of biological assemblies. In this study, the reactivities and tendencies to form easily detectible products for all 20 (common) amino acid side chains along with cystine are directly compared using various standards. Although we have previously reported on the oxidation of many of these residues, this study includes a detailed examination of the less reactive residues and better defines their usefulness in hydroxyl radical-mediated footprinting experiments. All 20 amino amides along with cystine and a few tripeptides were irradiated by [gamma]-rays, the products were analyzed by electrospray mass spectrometry, and rate constants of modification were measured. The reactivities of amino acid side chains were compared based on their loss of mass spectral signal normalized to the rate of loss for Phe or Pro that were radiolyzed simultaneously to serve as internal standards. In this way, accurate quantitation of relative rates could be assured. A reactivity order of amino acid side chains was obtained as Cys > Met > Trp > Tyr > Phe > cystine > His > Leu, Ile > Arg, Lys, Val > Ser, Thr, Pro > Gin, Glu > Asp, Asn > Ala > Gly. Ala and Gly are far too unreactive to be useful probes in typical experiments and Asp and Asn are unlikely to be useful as well. Although Ser and Thr are more reactive than Pro, which is known to be a useful probe, their oxidation products are not easily detectible. Thus, it appears that 14 of the 20 side chains (plus cystine) are most likely to be useful in typical experiments. Since these residues comprise ~65% of the sequence of a typical protein, the footprinting approach provides excellent coverage of the side-chain reactivity for proteins.

Hydroxyl radical-mediated footprinting permits detailed examination of structure and dynamic processes of proteins and large biological assemblies, as changes in the rate of reaction of radicals with target peptides are governed by changes in the solvent accessibility of the side-chain probe residues. The precise and accurate determination of peptide reaction rates is essential to successfully probing protein structure using footprinting. In this study, we specifically examine the magnitude and mechanisms of secondary oxidation occurring after radiolytic exposure and prior to mass spectrometric analysis. Secondary oxidation results from hydrogen peroxide and other oxidative species generated during radiolysis, significantly impacting the oxidation of Met and Cys but not aromatic or other reactive residues. Secondary oxidation of Met with formation of sulfoxide degrades data reproducibility and inflates the perceived solvent accessibility of Met-containing peptides. It can be suppressed by adding trace amounts of catalase or millimolar Met-NH2 (or Met-OH) buffer immediately after irradiation; this leads to greatly improved adherence to first-order kinetics and more precise observed oxidation rates. The strategy is shown to suppress secondary oxidation in model peptides and improve data quality in examining the reactivity of peptides within the Arp2/3 protein complex. Cysteine is also subject to secondary oxidation generating disulfide as the principal product. The disulfides can be reduced before mass spectrometric analysis by reducing agents such as TCEP, while methionine sulfoxide is refractory to reduction by this reagent under typical reducing conditions.

Protein footprinting based on hydroxyl radical-mediated modification and quantitative mass spectroscopic analysis is a proven technique for examining protein structure, protein--ligand interactions, and structural allostery upon protein complex formation. The reactive and solvent-accessible amino acid side chains function as structural probes; however, correct structural analysis depends on the identification and quantification of all the relevant oxidative modifications within the protein sequence. Sulfur-containing amino acids are oxidized readily and the mechanisms of oxidation are particularly complex, although they have been extensively investigated by EPR and other spectroscopic methods. Here we have undertaken a detailed mass spectrometry study (using electrospray ionization mass spectrometry and tandem mass spectrometry) of model peptides containing cysteine (Cys-SH), cystine (disulfide bonded Cys), and methionine after oxidation using [gamma]-rays or synchrotron X-rays and have compared these results to those expected from oxidation mechanisms proposed in the literature. Radiolysis of cysteine leads to cysteine sulfonic acid (+48 Da mass shift) and cystine as the major products; other minor products including cysteine sulfinic acid (+32 Da mass shift) and serine (-16 Da mass shift) are observed. Radiolysis of cystine results in the oxidative opening of the disulfide bond and generation of cysteine sulfonic acid and sulfinic acid; however, the rate of oxidation is significantly less than that for cysteine. Radiolysis of methionine gives rise primarily to methionine sulfoxide (+16 Da mass shift); this can be further oxidized to methionine sulfone (+32 Da mass shift) or another product with a -32 Da mass shift likely due to aldehyde formation at the [gamma]-carbon. Due to the high reactivity of sulfur-containing amino acids, the extent of oxidation is easily influenced by secondary oxidation events or the presence of redox reagents used in standard proteolytic digestions; when these are accounted for, a reactivity order of cysteine > methionine ~ tryptophan > cystine is observed.

Hydroxyl radical-mediated footprinting coupled with mass spectroscopic analysis is a new technique for mapping protein surfaces, identifying structural changes modulated by protein--ligand binding, and mapping protein--ligand interfaces in solution. In this study, we examine the radiolytic oxidation of aspartic and glutamic acid residues to probe their potential use as structural probes in footprinting experiments. Model peptides containing Asp or Glu were irradiated using white light from a synchrotron X-ray source or a cesium-137 [gamma]-ray source. The radiolysis products were characterized by electrospray mass spectrometry including tandem mass spectrometry. Both Asp and Glu are susceptible to radiolytic oxidization by [gamma]-rays or synchrotron X-rays. Radiolysis results primarily in the oxidative decarboxylation of the side chain carboxyl group and formation of an aldehyde group at the carbon next to the original carboxyl group, giving rise to a characteristic product with a -30 Da mass change. A similar oxidative decarboxylation also takes place for amino acids with C-terminal carboxyl groups. The methylene groups in the ASp and Gin side chains also undergo oxygen addition forming ketone or alcohol groups with mass changes of +14 and +16 Da, respectively. Characterizing the oxidation reactions of these two acidic residues extends the number of useful side chain probes for hydroxyl radical-mediated protein footprinting from 10 (Cys, Met, Trp, Tyr, Phe, Arg, Leu, Pro, His, Lys) to 12 amino acid residues, thus enhancing our ability to map protein surface structure and in combination with previously identified basic amino acid probes can be used to examine molecular details of protein--protein interactions that are driven by electrostatics.

Protein footprinting utilizing hydroxyl radicals coupled with mass spectrometry has become a powerful technique for mapping the solvent accessible surface of proteins and examining protein-protein interactions in solution. Hydroxyl radicals generated by radiolysis or chemical methods efficiently react with many amino acid residue side chains, including the aromatic and sulfur-containing residues along with proline and leucine, generating stable oxidation products that are valuable probes for examining protein structure. In this study, we examine the radiolytic oxidation chemistry of histidine, lysine, and arginine for comparison with their metal-catalyzed oxidation products. Model peptides containing arginine, histidine, and lysine were irradiated using white light from a synchrotron X-ray source or a cesium-137 [gamma]-ray source. The rates of oxidation and the radiolysis products were primarily characterized by electrospray mass spectrometry including tandem mass spectrometry. Arginine is very sensitive to radiolytic oxidation, giving rise to a characteristic product with a 43 Da mass reduction as a result of the loss of guanidino group and conversion to [gamma]-glutamyl semialdehyde, consistent with previous metal-catalyzed oxidation studies. Histidine was oxidized to generate a mixture of products with characteristic mass changes primarily involving rupture of and addition to the imidazole ring. Lysine was converted to hydroxylysine or carbonylysine by radiolysis. The development of methods to probe these residues due to their high frequency of occurrence, their typical presence on the protein surface, and their frequent participation in protein-protein interactions considerably extends the utility of protein footprinting.

Influences of the gas mixtures of carbon dioxide and water vapor with different water vapor content on the thermal properties of cokes were studied at 1,373 k using a high-temperature gas-solid reaction device to clarify the action mechanism of water vapor in the dissolution loss of metallurgical coke in the blast furnace. Furthermore, the reaction depth and the microstructure of coke samples with different water vapor content were studied. The results showed that the reactivity of cokes was significantly improved by steam, and coke strength after the reaction was significantly weakened. Cokes with strong reactivity were more affected by water vapor. When H2O content was 0 and 11.1%, the reactivity indices of cokes with strong reactivity were 2.03 and 1.67 times that of cokes with poor reactivity, respectively. The influence of H2O on the strength ratio of two kinds of cokes after the reaction was ignored when H2O content exceeded 50.1%. The analysis of coke reaction depth after the reaction under different H2O content showed that the solution loss reaction between H2O and coke is mainly concentrated on the coke surface, while CO2 can penetrate into the coke to react. In addition, by comparing two kinds of coke with different reactivity, it is found that coke with higher reactivity is more sensitive to water vapor. The micromorphologies of cokes after reactions showed that water vapor significantly affected the pore and pore sizes of cokes. When water vapor content increased, the pore sizes of cokes increased, with the thinner pore wall and the increased number of new pores. [ABSTRACT FROM AUTHOR]