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High-quality perovskite films are essential for achieving high performance of optoelectronic devices; However, solution-processed perovskite films are known to suffer from compositional and structural inhomogeneity due to lack of systematic control over the kinetics during the formation. Here, the microscopic homogeneity of perovskite films is successfully enhanced by modulating the conversion reaction kinetics using a catalyst-like system generated by a foaming agent. The chemical and structural evolution during this catalytic conversion is revealed by a multimodal synchrotron toolkit with spatial resolutions spanning many length scales. Combining these insights with computational investigations, a cyclic conversion pathway model is developed that yields exceptional perovskite homogeneity due to enhanced conversion, having a power conversion efficiency of 24.51% for photovoltaic devices. This work establishes a systematic link between processing of precursor and homogeneity of the perovskite films.

[Display omitted] • Simulate breakage and oxidation of clay aging by sonication and plasma treatment. • Investigate the role of surface properties of aged clay in CO 2 hydrate formation. • Disrupted Si-O rings and grafted –OH of VMNs weaken their interaction with water. • Disordered interfacial water caused by clay aging prolong CO 2 hydrate nucleation. Clay-based marine sediments have great potential for safe and effective carbon dioxide (CO 2) encapsulation by storing enormous amounts of CO 2 in solid gas hydrate form. However, the aging of clay with time changes the surface properties of clay and complicates the CO 2 hydrate formation behaviors in sediments. Due to the long clay aging period, it is difficult to identify the role of clay aging in the formation of CO 2 hydrate in marine sediments. Here, we used ultrasonication and plasma treatment to simulate the breakage and oxidation of clay nanoflakes in aging and investigated the influence of clay aging on CO 2 hydrate formation kinetics. We found that the breakage and oxidation of clay nanoflakes would disrupt the siloxane rings and graft hydroxyl on the clay nanoflakes. This decreased the negative charge density of clay nanoflakes and weakened the interfacial interaction of clay nanoflakes with the surrounding water. Therefore, the small clay nanoflakes enriched in hydroxyl would disrupt the surrounding tetrahedral water structure analogous to the CO 2 hydrate, resulting in the prolongation of CO 2 hydrate nucleation. These results revealed the influence of the structure-function relationship of clay nanoflakes with CO 2 hydrate formation and are favorable for the development of hydrate-based CO 2 storage. [ABSTRACT FROM AUTHOR]

The synthesis of forsterite can be challenging because the initial oxides react slowly and undesirable compounds like enstatite (MgSiO 3) can form instead of forsterite (Mg 2 SiO 4). Although several methods have been developed to overcome these challenges, the synthesis of forsterite using the solid-state reaction of nanopowders has not been investigated. This study aims to explore the possibility of producing forsterite by reacting MgO and SiO 2 nano-powder. The initial oxides were wet ball milled, dried, and reaction sintered. Spectroscopy and microscopy methods were used to analyze the formed phases and study the formation kinetics. The density, coefficient of thermal expansion (CTE), and hardness of sintered samples were measured using a densimeter, a dilatometer, and a hardness tester, respectively. The results demonstrated that it is possible to synthesize forsterite by solid state reaction of pure MgO and SiO 2 nano-powders. The reaction between the two compounds begins at a temperature as low as 860 °C and leads to the formation of forsterite by a two-step formation mechanism. The first reaction involves the reaction of MgO and SiO 2 to form enstatite, and the second one produces forsterite as a result of enstatite reacting further with MgO. The activation energy values ranged from 1028.89 to 1105.655 kJ/mol for the formation of forsterite, and from 456.316 to 488.08 kJ/mol for the formation of enstatite. Monolithic forsterite was completely formed at a low temperature of 1200 °C for a relatively short duration of 2 h. The sample sintered at 1400 °C for 2 h, had a density of 2.96 g/cm3, a Vickers hardness of 7.64 GPa, and a coefficient of thermal expansion of 10.24 × 10−6/K measured in the temperature range of 200–1300 °C. [ABSTRACT FROM AUTHOR]

Facile evaluation of formation kinetics of key intermediate is crucial for a comprehensive understanding of electrochemical ammonia oxidation reaction (AOR) mechanisms and the design of efficient electrocatalysts. Currently, elucidating the formation kinetics of key intermediate associated with rate‐determining step is still challenging. Herein, 4‐phtalamide‐N‐(4′‐methylcoumarin) naphthalimide (CF) is developed as a molecular probe to detect N2H4 intermediate during AOR via electrochemiluminescence (ECL) and further investigated the formation kinetics of N2H4 on Pt catalysts with different crystal planes. CF probe can selectively react with N2H4 to release ECL substance luminol. Thus, N2H4 intermediate as a key intermediate can be sensitively and selectively detected by ECL during AOR. For the first time, Pt(100) facet is discovered to exhibit faster N2H4 formation kinetics than Pt(111) facet, which is further confirmed by Density functional theory calculation and the finite element simulation. The AOR mechanism under the framework of Gerischer and Mauerer is further validated by examining N2H4 formation kinetics during the dimerization process (NH2 coupling). The developed ECL active probe and the discovered facet‐dependent formation kinetics of key intermediates provide a promising new tool and strategy for the understanding of electrochemical AOR mechanisms and the design of efficient electrocatalysts. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) hydrates have garnered significant interest as a promising technology for CO2 capture and storage due to its high storage capacity and moderate operating conditions. The kinetics of CO2 hydrate formation is a critical factor in determining the feasibility of hydrate-based CO2 capture and storage technologies. This study systematically investigates the promotional effects of the amino acid L-tryptophan (L-trp) on CO2 hydrate formation kinetics and morphology under stirred and unstirred conditions. In the stirred system, experiments were conducted in a high-pressure 100 mL reactor with 0.05, 0.10, and 0.30 wt% L-trp solution. CO2 gas uptake kinetics and morphological evolution were monitored using a high-resolution digital camera. Results showed that L-trp promoted CO2 hydrate formation kinetics without delay, with rapid CO2 consumption upon nucleation. Morphological evolution revealed rapid hydrate formation, wall-climbing growth, and dendritic morphology filling the bulk solution. Under unstirred conditions, experiments were performed in a larger 1 L reactor with 0.1 wt% and 0.5 wt% L-trp solutions to assess the influence of additive concentration on hydrate formation thermodynamics and kinetics. Results demonstrated that L-trp influenced both thermodynamics and kinetics of CO2 hydrate formation. Thermodynamically, 0.1 wt% L-trp resulted in the highest hydrate formation, indicating an optimal concentration for thermodynamic promotion. Kinetically, increasing L-trp concentration from 0.1 wt% to 0.5 wt% reduced formation time, demonstrating a proportional relationship between L-trp concentration and formation kinetics. These findings provide insights into the role of L-trp in promoting CO2 hydrate formation and the interplay between additive concentration, thermodynamics, and kinetics. The results can inform the development of effective hydrate-based technologies for CO2 sequestration, highlighting the potential of amino acids as promoters in gas hydrate. [ABSTRACT FROM AUTHOR]

This research undertakes a comparative study between compacted phosphate-based (CPG) and alkaline-based (CAG) geopolymeric materials. The obtained materials underwent comprehensive evaluation through mechanical, physical, and chemical analyses. CPG exhibited superior mechanical strength, demonstrating an exponential growth with curing age in contrast to CAG. Both materials exhibited stable density over time, with CPG displaying a notably higher density attributed to its enhanced reactivity in an acidic medium. Dimensional variations revealed stable dimensions for CPG and subtle shrinkage for CAG, potentially associated with an observed efflorescence phenomenon. Visual assessments during water immersion highlighted the enhanced stability of CPG. Chemical analyses confirmed the persistence of mineralogical phases, such as quartz and illite, and the emergence of an amorphous geopolymeric network in both CPG and CAG samples. CPG materials featured aluminum phosphate phases, reinforcing structural integrity, while CAG materials exhibited sodium carbonate phases, introducing impurities, elucidating the superior performance of CPG over CAG. For the formation kinetics, CPG exhibited a faster reaction time than CAG, as evidenced by the evolution of pH, densification rate, and FTIR band over curing time. [ABSTRACT FROM AUTHOR]

Here we report on the characterizations (mass spectrometry and NMR) and kinetic investigations related to the formation of trinuclear complexes [Eu3L]9+ in metal excess. The NMR studies of the mixture containing the tripodal ligand L and Eu(III) involved the identification and attribution of signals at variable temperature. Kinetic spectrophotometric studies were performed with a stopped flow device at low temperature in metal excess. Two pathways were investigated: (i) a direct complexation of L; (ii) a conversion of the tetranuclear edifice [Eu4L4]12+. Kinetic measurements show that the building of the trimetallic species involves two main steps. In the first one, Eu(III) ions are rapidly bound to each ligand strand. The second step is related to a slow rearrangement within the complex. The conversion of the tetranuclear complex occurs in globally fast two successive steps, but these are slower than a direct binding of Eu(III) to L, which suggests a rate limiting attack of the compact tetranuclear edifice. Although this study focuses on the formation kinetics between Ln(III) and tritopic ligands in metal excess, far from the stoichiometry of tetrahedral helicates, it provides a valuable insight into the mechanism of complexation under pseudo-first order conditions. [ABSTRACT FROM AUTHOR]

The Maillard reaction system of glucose and glycine was applied to study the formations of furfural compounds. The effects of glucose/glycine molar concentration ratio, initial pH, heating temperature and time on the formations of 5-hydroxymethylfurfural (HMF), 2-furfural (F) and 5-methyl-2-furfural (MF) were evaluated. The kinetic equations of HMF, F and MF were established and their apparent activation energies were also predicted. The results showed that: Glucose/glycine molar concentration ratio had great influence on the formations of furfural compounds. The formation of HMF continued to increase with the increase of ratio, and the formations of F and MF reached the maximum when the ratio was 1:1. The acidic pH conditions could promote the formation of HMF, while the neutral and alkaline pH conditions were conducive to the formation of F. The total amount of furfural compounds decreased rapidly with the increase of pH. The amounts of HMF, F, and MF in the glucose-glycine reaction system increased with the increase of heating temperature and time. The formations of HMF and F in glucose and glycine model followed first-order kinetics model at lower temperatures (HMF: 70~110 ℃; F: 70 ℃), while their formations were in accordance with zero-order kinetics model at higher temperatures (HMF: 130 ℃; F: 90~130 ℃). The formation of MF followed zero-order kinetics model at 90~130 ℃. The results would provide guidance on the production and control of HMF, F, and MF in the food thermal processing industry.

Considering the ever-increasing interests in natural gas hydrates, a better and more precise knowledge of how host sediments interact with hydrates and affect the formation process is crucial. Yet less is reported for the effects of sediments on structure II hydrate formation with complex guest compositions. In this study, experimental simulations were performed based on the natural reservoir in Qilian Mountain permafrost in China (QMP) due to its unique properties. Mixed gas hydrates containing CH4, C2H6, C3H8, and CO2 were synthesized with the presence of natural sediments from QMP, with quartz sands, and without sediments under identical p–T conditions. The promoting effects of sediments regardless of the grain size and species were confirmed on hydrate formation kinetics. The ice-to-hydrate conversion rate with quartz sand and natural QMP sediments increased by 23.5% and 32.7%, respectively. The compositions of the initial hydrate phase varied, but the difference became smaller in the resulting hydrate phases, having reached a steady state. Beside the structure II hydrate phase, another coexisting solid phase, neither ice nor structure I hydrate, was observed in the system with QMP sediments, which was inferred as an amorphous hydrate phase. These findings are essential to understand the mixed gas hydrates in QMP and may shed light on other natural hydrate reservoirs with complex gas compositions. [ABSTRACT FROM AUTHOR]

A new dendrimeric cobalt(II) complex CoP has been obtained when reacting (5,15-bis[3,5-bis(tert-butyl)phenyl]-10,20-bis{4,6-bis[3,5-bis(3,6-di-tert-butylcarbazole-9-yl)phenoxy]pyrimidin-5-yl}porphine with Co(AcO)2·4H2O. The process of two-step two-way coordination of 1-methyl-2-(pyridin-4'-yl)-3,4-fullero[60]pyrrolidine (PyC60) with cobalt(II) porphyrin ends with the formation of a stable 1 : 2 complex, a triad of composition (PyC60)2CoP. The process has been completely kinetically described using UV-vis and fluorescent spectroscopy data. The stability constant (K) of the coordination complex is (9.9 ± 2.4) × 108 L2 mol–2 (log K = 9.0). The chemical structure of the triad has been determined by UV-vis, 1H NMR, and IR spectroscopy. The effect of PyC60 fluorescence quenching in the triad has been found and studied, and the static mechanism of the quenching process has been substantiated. The result can be used in optoelectronics to optimize the structures of donor–acceptor systems with the property of photoinduced electron transfer. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a food‐borne pathogen that quickly forms biofilm on meat contact surfaces and thus poses a serious threat to the safety of the meat industry. This study evaluated the attachment, survival, and growth of S. aureus biofilm with exposure to environmental factors in the meat industry by simulated ready‐to‐eat (RTE) cooked beef product contamination scenarios. The results indicated that the meat‐borne S. aureus biofilm formation dynamic could be divided into four different phases: initial adhesion (4–12 h), exponential (12–24 h), slow growth (1–3 days), and stationary (3–7 days). Meat‐borne S. aureus has strong adhesion and biofilm formation ability, and its biofilm exhibits persistence, high‐intensity metabolic activity, aerotaxis, and strain heterogeneity. This study has also demonstrated that in the long‐term existence of meat‐borne S. aureus biofilm on stainless steel and plexiglass surfaces (>7 days, 7.2–8.8 log CFU/cm2), expose to RTE cooked beef products, may cause it to become high‐risk contaminated food. Meat‐borne S. aureus that forms a dense and rough concave‐convex in the shape of biofilm architecture was observed by scanning electron microscopy, consisting of complex components and adhesion of living and dead cells. This was further confirmed by the meat‐borne S. aureus biofilm on the stainless steel surface by attenuated total reflectance Fourier transformed infrared spectroscopy, and the dominant peaks in biofilm spectra were mainly associated with proteins, polysaccharides, amino acid residues, and phospholipids (>50%). These findings may help in the identification of the main sources of contamination within the meat industry and the subsequent establishment of strategies for biofilm prevention and removal. Practical Application: This study revealed the meat‐borne S. aureus biofilm formation mechanism and found that it exhibited strong colonization and biofilm‐forming ability, which can persist on the contact surfaces of ready‐to‐eat beef products. These initial findings could provide information on the behavior of meat‐borne S. aureus biofilm attached to meat contact surfaces under conditions commonly encountered in meat environments, which help to support the determination of the main sources of contamination within the meat industry and the subsequent establishment of strategies for biofilm prevention and removal. It was also helpful in controlling biofilm contamination and improving meat safety to minimize it. [ABSTRACT FROM AUTHOR]

1. Dimethoate is an organophosphate insecticide. The objective of this work was to determine the enzymatic kinetics of metabolism of dimethoate and its active metabolite omethoate in rats and humans and obtain key input parameters for physiologically based pharmacokinetic (PBPK) model. 2. First, the intrinsic clearance of dimethoate expressed as formation rate of omethoate was determined to be ∼42-fold lower in human liver microsomes (HLM) (0.39 µL/min/mg) than in rat liver microsomes (RLM) (16.6 µL/min/mg) by an LC/MS/MS method. Next, dimethoate clearance in liver microsomes was determined using parent depletion and total [14C]-metabolite formation methods. Results from both approaches showed slower clearance of dimethoate in HLM (1.1–3.3 µL/min/mg) than in RLM (12.7–17.4 µL/min/mg). 3. Investigation of in vitro enzymatic kinetics of omethoate demonstrated that the intrinsic clearance rates for omethoate in adult and juvenile RLM and HLM were similar. No significant turnover of dimethoate was apparent in rat cytosol or plasma. In contrast, degradation of omethoate in human plasma was slightly higher than in rat plasma. 4. Finally, toxicokinetics of dimethoate were determined in adult and juvenile rats. In both age groups, following oral dosing, absorption of dimethoate was rapid with formation of significant amounts of omethoate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The concentration effect on enhancing the storage capacity of ECP was explored. • ECP showed a strong thermodynamic promoter for enclathration of natural gas. • The highest gas uptake occurred at ECP (6.5 mol%) + natural gas hydrate case. • As ECP concentration increased, CH 4 occupancy and hydrate conversion increased. • Stoichiometrically excess ECP can improve hydrate formation kinetics. With the growing demand for energy, natural gas has gained attention as a lower-emission option compared to the other conventional fossil fuels such as oil and coal. Consequently, there is significant interest in developing energy-efficient natural gas storage technologies. Gas hydrate-based storage offers a promising solution due to its relatively high capacity at moderate operating pressure and temperature conditions. Epoxycyclopentane (ECP) has emerged as an effective thermodynamic promoter, but its limited miscibility in water can influence storage capacity depending on its concentration. This study investigated the effect of varying ECP concentrations (4.0, 5.0, 5.6, 6.0, 6.5, and 7.0 mol%) on the gas storage capacity of hydrates formed from pure CH 4 and a natural gas mixture (CH 4 (90%) + C 2 H 6 (7%) + C 3 H 8 (3%)). We systematically examined thermodynamic stability, formation kinetics, crystalline structure, and guest distribution in ECP hydrates. The results revealed that ECP significantly promoted hydrate thermodynamic formation across all concentrations, with the optimal concentration for natural gas storage identified as 6.5 mol%, which achieved the highest gas storage capacity. Synchrotron XRD confirmed the formation of sII hydrates in both ECP + natural gas and ECP + CH 4. Raman and 13C solid-state NMR analyses showed no CH 4 occupancy in sII-L, which suggests the absence of pure natural gas hydrates. Cage occupancy estimation revealed that the highest CH 4 occupancy in sII-S cages occurred at 6.5 mol% ECP, which contributed to an enhanced gas uptake. Time-dependent in-situ Raman and NMR analyses demonstrated that excess ECP can induce a two-step formation process, which further enhances storage capacity. Hence, we believe that these findings offer valuable insights into optimizing ECP concentration for the development of hydrate-based natural gas storage. [ABSTRACT FROM AUTHOR]

Desalination using hydrates is a developing field, and initial research promises a commercially feasible approach. The current study proposes the natural amino acid, namely tryptophan, as a biodegradable gas hydrate promotor for desalination applications to speed up the hydrate formation process. Its kinetic behavior and separation capabilities with CO2 hydrates were investigated. The studies were carried out with varying concentrations (0.5, 1, and 2 wt.%) of tryptophan at different experimental temperatures (274.15, 275.15, 276.15, and 277.15 K) at 3.5 and 4.0 MPa pressure and 1 wt.% brine concentration. The induction time, initial formation rates, gas uptake, and water recovery are characterized and reported in this work. Overall finding demonstrated that tryptophan efficiently acted as a kinetic hydrate promotor (KHP), and increased tryptophan quantities further supported the hydrate formation for almost all the studied conditions. The formation kinetics also demonstrated that it shortens the hydrate induction time by 50.61% and increases the 144.5% initial formation rate of CO2 hydrates for 1 wt.% addition of tryptophan at 274 K temperature and 4.0 MPa pressure condition. The study also discovered that at similar experimental conditions, 1 wt.% tryptophan addition improved gas uptake by 124% and water recovery moles by 121%. Furthermore, the increased concentrations of tryptophan (0.5–2 wt.%) further enhance the formation kinetics of CO2 hydrates due to the hydrophobic nature of tryptophan. Findings also revealed a meaningful link between hydrate formation and operating pressure observed for the exact temperature settings. High pressures facilitate the hydrate formation by reduced induction times with relatively higher formation rates, highlighting the subcooling effect on hydrate formation conditions. Overall, it can be concluded that using tryptophan as a biodegradable kinetic promotor considerably enhances the hydrate-based desalination process, making it more sustainable and cost-effective. [ABSTRACT FROM AUTHOR]

Nanoparticles based on bovine serum albumin (BSA), which shares 76% homology with human serum albumin (HSA), have emerged as a promising candidate for the efficient delivery of anticancer drugs. Thermal-driven self-assembly is a novel organic solvent-free approach to produce albumin nanoparticles. In our previous study, some features of this nanoparticle such as drug loading efficiency, drug encapsulation efficiency and drug release kinetics have been evaluated. However, the formation mechanism that determines the above nanoparticle properties remains unclear. Here, we investigated the formation kinetics and mechanism using spectroscopic methods including fluorescence spectroscopy, circular dichroism (CD) and differential scanning calorimetry (DSC). We also applied chemical analysis methods that measured the content changes of albumin active groups and vanillin. To verify the covalent networks in the nanoparticles, trypsin and glutathione (GSH) were used separately to cleave the peptide bonds and disulfide bridges, and dynamic light scattering (DLS) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were used to analyze the degraded samples. BSA nanoparticles started to form at 10 min and were completely formed at 120 min. With the digestion of trypsin, more than 50% of the nanoparticles were degraded within 60 min. CD spectra showed that α-helical structure of BSA decreased from 42.3% to 39.8% and 37.7% after heating for 10 and 60 min, respectively. In the DSC thermogram, the melting peak of BSA nanoparticles was 229.14℃, which is about 12℃ higher than the physical mixture of BSA and vanillin, indicating that chemical reactions occurred during the nanoparticle formation and formed a new more stable substance. Moreover, the results of active group assay, GSH degradation and SDS-PAGE experiments also proved that disulfide bonds and peptide bonds were formed between BSA molecules, whereas Schiff bases were formed between BSA and vanillin molecules. Formation kinetics and degradation behavior are important properties to characterize albumin nanoparticles and should be paid attention to. Not only that, this study also provides an effective way to study the formation mechanism of protein-based nanodrug delivery systems. [ABSTRACT FROM AUTHOR]

Formation kinetics and equilibrium thermodynamics are fundamental knowledge for predicting microstructure and properties during materials processing and utilization. This work prepared high purity Bi 12 TiO 20 , Bi 4 Ti 3 O 12 and Bi 2 Ti 4 O 11 compounds and characterized these compounds by in-suit X-ray diffraction, scanning electron microscope, energy dispersive spectrometer as well as calorimetry. Based on the experimental data obtained in this work and the literature, a thermodynamic description of the Bi 2 O 3 –TiO 2 system was carried out, a thermodynamic database as well as the calculated phase diagram of the system was provided. The discrepancy between the present calculation with the experimental data were discussed, the formation kinetics of the compounds was explained and the bismuth titanate ceramics with tailored structure and specific physical properties were sintered. [ABSTRACT FROM AUTHOR]

In this study, Tween 80 was chosen as a kinetic promoter to study the effect of non-ionic surfactant on CO2 hydrate formation kinetics. The experiments were carried out in a thermostatic reactor using CO2-rich gas mixtures with Tween 80 (0–3000 ppm) in both clathrate hydrates and tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrates. Analysis of variance (ANOVA) was used to analyze the difference among experimental results, and a decision box was proposed to evaluate the performance of systems studied. The apparent improvement in the induction time, gas uptake yield, and gas separation performance were observed in 1000-ppm or 2000-ppm Tween 80 in semiclathrate hydrates. Increased pressure further improved the kinetic promotion effect of Tween 80. However, a higher concentration of 3000-ppm Tween 80 was found to result in an inhibition effect on CO2 uptake yield in semiclathrate hydrates, although the induction time remained short. Compared with common anionic and cationic surfactants, 2000-ppm Tween 80 showed the best CO2 separation performance from gas mixtures in semiclathrate hydrates. No inhibition effect was observed in clathrate hydrates with studied concentrations of Tween 80.

[Display omitted] • MEG alters hydrate growth pattern, preventing hydrate film formation at interface. • MEG induces loose and low-saturation hydrate in solution, followed by solidification. • MEG leads to the formation of dense surface hydrate blocks at under-inhibition. • MEG concentration below 20 % does not exhibit significant self-inhibition of hydrate formation. Natural gas hydrate blockages pose a major risk to deepwater oil and gas development. Thermodynamic under-inhibition is a cost-effective hydrate management strategy, but the impact of mono ethylene glycol (MEG) on hydrate formation kinetics and mass transfer at the gas–water interface requires further understanding for hydrate-related flow assurance. This study investigates the kinetics and morphology of hydrate growth from MEG solutions using in situ micro X-ray CT and a macro transparent reactor. MEG concentration emerged as the primary factor influencing hydrate growth morphology. Findings revealed that MEG alters the growth morphology of gas hydrates by inhibiting the formation of a hydrate film at the gas–liquid interface and inducing flocculent hydrate growth within the solution. MEG can also induce the formation of low-saturation hydrates, with no significant self-inhibition observed at concentrations below 20 %. Over time, a dense hydrate shell tended to form on the surface of the hydrate lump, increasing the risk of blockage. Additionally, it was observed that subcooling also affects the hydrate growth morphology; higher subcooling accelerates the hydrate growth rate and increases the density of the formed hydrate. This research explored the mechanisms underlying hydrate formation in under-inhibited systems, aiming to extend the safe operational boundary for oil and gas transportation and provide theoretical support for deepwater hydrate management. [ABSTRACT FROM AUTHOR]

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ABSTRACT: Innovative gas hydrate-based applications and hydrate flow assurance problems of oil & gas pipelines have enabled new opportunities to develop and deploy biocompatible or green low-dosage hydrate promoters and inhibitors, respectively. In this context, we evaluate the performance of a biocompatible additive, lecithin (extracted from egg yolk), for the formation kinetics of binary cyclopentane (CP)-carbon dioxide (CO2) hydrates simulating to the structure-II hydrate of natural gas. A high-pressure visual autoclave is employed in this study to map the morphological observations with the gas hydrate kinetic data. Multiple experiments are performed to examine the inhibition or promotional effect of lecithin in saline (3.0 wt % NaCl) and non-saline water systems at low pressure of 1.0 MPa while utilizing the various CP content (1.5, 3.0, and 6.0 mol%) and 500 to 5000 ppm of lecithin. Moreover, we evaluate the effect of salinity and lecithin on the thermodynamic hydrate equilibrium conditions. The results imply that the presence of lecithin retards the hydrate formation kinetics. However, no shift in the equilibrium frontier is observed. Importantly, we propose a chemical potential based kinetic model by accounting the influence of additives, vapor-liquid interfacial area, temperature and pressure on gas hydrate formation. This model has closely interpreted the experimental data of hydrate former uptake during binary hydrate formation in the presence and absence of lecithin. Our findings highlight the potential of engaging lecithin for hydrate inhibition to mitigate the flow assurance issues and also offer comprehensive insights toward integrated hydrate-based carbon capture and seawater desalination approach.

The kinetics and mechanism of ternesite formation (calcium sulfosilicate, Ca5(SiO4)2SO4, C5S2$) were investigated by studying the reaction between beta-dicalcium silicate (β-C2S) and calcium sulfate dihydrate (CaSO4∙2H2O). Mineralogical composition development was monitored using X-ray diffraction (XRD) and backscattered scanning electron microscopy (BSEM) coupled to energy-dispersive X-ray spectroscopy (EDS). Ternesite can form in the 1100 to 1200 °C range by the solid-phase reaction of β-C2S and CaSO4. The formation of ternesite is favored by increasing the sintering temperature or extending the sintering time. The solid-phase reaction is carried out by diffusion of CaSO4 to β-C2S. The kinetics equation of ternesite is consistent with three-dimensional diffusion models (3-D model, D3 model or Jander model). The equation of the D3 model is 1 − 2α/3 − (1 − α)2/3 = kt. On the basis of the Arrhenius equation, the activation energy of ternesite is 239.8 kJ/mol. [ABSTRACT FROM AUTHOR]

Chirality plays a pivotal role in both the origin of life and the self-assembly of materials. However, the governing principles behind chirality transfer in hierarchical self-assembly across multiple length scales remain elusive. Here, we propose a concise and versatile simulation strategy using the patchy particle chain model to investigate the self-assembly of rods interacting through chiral and aggregation interactions. We reveal that chiral interaction possessing an entropic nature, amplifies the fluctuations and twists in the alignment of rods, while aggregation interaction serves as a foundational platform for aggregation and assembly. When both interactions exhibit moderate absolute and relative values, their synergistic interplay facilitates the chirality transfer from rods to assemblies, resulting in the formation of chiral mesoscale ordered structures. Furthermore, we observe a two-step chirality transfer process by monitoring the formation kinetics of the twisted assemblies. This work not only provides a comprehensive insight into chirality transfer mechanisms, but also introduces a versatile mesoscale simulation framework for exploring the role of chirality in hierarchical self-assembly.

• The formation process of fungal biofilms include: induction, exponential, stationary and sloughing off. • The suitable conditions for the formation of fungal biofilms: 28 °C, neutral or weakly acidic, and rich nutrition. • The potential of the fungal biofilms formation in actual groundwater were limited to carbon level. • The resistance of fungal biofilms to disinfectants is as following: A. niger > T. harzianum > P. polonicum. • The control efficiency of disinfectants is as following: chlorine dioxide > chlorine > chloramine. Filamentous fungi can enter drinking water supply systems in various ways, and exist in suspended or sessile states which threatens the health of individuals by posing a high risk of invasive infections. In this study, the biofilms formation kinetics of the three genera of fungal spores, Aspergillus niger (A. niger) , Penicillium polonicum (P. polonicum) and Trichoderma harzianum (T. harzianum) isolated from the groundwater were reported, as well as the effects of water quality parameters were evaluated. In addition, the efficiency of low- concentrations of chlorine-based disinfectants (chlorine, chlorine dioxide and chloramine) on controlling the formation of fungal biofilms was assessed. The results showed that the biofilms formation of the three genera of fungi could be divided into the following four phases: induction, exponential, stationary and sloughing off. The optimum conditions for fungal biofilms formation were found to be neutral or weakly acidic at 28 °C with rich nutrition. In fact, A. niger, P. polonicum , and T. harzianum were not observed to form mature biofilms in actual groundwater within 120 hr. Carbon was found to have the maximum effect on the fungal biofilms formation in actual groundwater, followed by nitrogen and phosphorus. The resistance of fungal species to disinfectants during the formation of biofilms decreased in the order: A. niger > T. harzianum > P. polonicum. Chlorine dioxide was observed to control the biofilms formation with maximum efficiency, followed by chlorine and chloramine. Consequently, the results of this study will provide a beneficial understanding for the formation and control of fungal biofilms. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon nanocrystals (SiNC) in silicon oxide is a promising material for many applications in micro- and nanoelectronics. This article develops a theory of the kinetics of SiNC formation with the both diffusion and reaction mechanisms of their formation being taken into account. The theoretical expressions obtained for the nanocrystals concentration change and silicon implanted in oxide and their sizes are consistent with experimental results and can be used to optimize the technological processes conditions of SiNC formation. [ABSTRACT FROM AUTHOR]

Using a mathematical model of competitive crystallization of polymorphic metals a numerical analysis of formation kinetics of the metastable polytype of lanthanum (µ-La), which is fixed in the products of quenching from the liquid state in a mixture with crystallization of the equilibrium f.c.c. β-modification, is carried out. The interval of rapidly quenched foils thicknesses is determined, within which the metastable µ-phase is formed in quantities sufficient for experimental detection. The calculated data agree with the results of X-ray phase analysis at the physically correct value of the free parameter of the model ΔGµβ = 5 J/mol, which has the meaning of the degree of metastability of µ-La. [ABSTRACT FROM AUTHOR]

Semi-clathrates are a class of inclusion compounds in which a part of guest molecule involves in the formation of cage structure along with water and the other remaining part of guest molecule occupies and stabilizes the gas hydrate structure. Semi-clathrate based carbon capture encages carbon dioxide in hydrate cages which is an energy-efficient and economical pathway for carbon dioxide capture. This study examines the kinetics of tetrabutyl ammonium flouride (TBAF) based carbon dioxide capture at near ambient temperatures and the impact of amino acids on hydrate formation have been examined. The promotion effect of three selected amino acids - L-methionine, L-tryptophan and L-leucine on TBAF mixed semi-clathrates has been documented in this work. Experiments were conducted with simulated flue gas mixture of 25.2% CO 2 /74.8% N 2 at 8 MPa pressure and temperatures of 293.2 K and 298.2 K. The morphology of hydrate growth and the composition of recovered CO 2 gas are also presented. Results indicate that lower TBAF concentration (10–20 wt%) experiments showcase an improved CO 2 selectivity of up to 70% in the hydrate phase and higher TBAF concentration improved the total amount of gas stored per mole of water with a maximum of about 10 mmol of gas/mol of water. The gas uptake was found to increase for higher concentrations (20 wt% and 33.7 wt%) of TBAF in the solution. The average gas uptake value increased from 2.43 mmol/mol (10 wt% TBAF) to 9.96 mmol/mol (33.7 wt% TBAF) during the hydrate formation at 298 K and 8 MPa. 20 wt% TBAF solution showed highest separation of CO 2 in hydrate phase. L methionine, L-tryptophan and L-Leucine amino acids in concentration range of 0.1 wt% - 2 wt% were used with 10 wt% TBAF solution amongst which 2 wt% L-methionine provided the best promotion. [Display omitted] • Semi-clathrate formation kinetics with amino-acids for post combustion CO 2 capture. • Near ambient temperature conditions envisaged for semi-clathrate formation. • Improved CO 2 selectivity with about 70% CO 2 enriched in the hydrate phase. • L-methionine amino acid promotes semi-clathrate hydrate formation from flue gas. [ABSTRACT FROM AUTHOR]

The kinetics of the formation of the light orange–coloured complex [Ru(CN)5D-PA]3− are studied spectrophotometrically through substitution of a coordinated H2O molecule in aquapentacyanoruthenate(II) [Ru(CN)5OH2]3− by interaction with D-penicillamine [D-PA] in aqueous medium at 490 nm (λmax of [Ru(CN)5D-PA]3−). The reaction is monitored under pseudo-first-order conditions, taking [D-PA] in excess over [Ru(CN)5OH23−]. The effects of various reaction parameters on the rate of the reaction are investigated. Experimental observations reveal that the variation in [D-PA] obeyed the first-order rate law while it is found to be invariant with [Ru(CN)5OH23−] in the whole experimental range. With ionic strength variation, as the reaction advances a decrease in the reaction rate is noticed. The product stoichiometry is assigned as 1:1. The ease of substitution at an H2O molecule in [Ru(CN)5OH23−] is considered on the basis of the electronic effect generated through interactions of the M–OH2 bond. A provisional mechanism based on the calculated results is proposed based on the slowest step of the reaction. [ABSTRACT FROM AUTHOR]

Hydrate-based gas separation is a potential technology for CO2 recovery and storage, and its products can be used for fire prevention and control in mines. Promoters are often employed to accelerate or moderate hydrate formation. In this study, experiments were performed to examine the effects of different concentrations of the thermodynamic promoter tetrahydrofuran (THF) and kinetic promoter sodium dodecyl sulphate (SDS) on CO2 hydrate formation under stirring. The results showed that THF significantly shortens the induction time of CO2 hydrates; however, because THF occupies a large cavity in the hydrate structure, it also reduces the gas absorption and hydrate formation rate. SDS has no obvious effect on the induction time of hydrates, but it can increase the gas storage density and hydrate formation rate. Using THF and SDS together consumed more CO2 than using THF alone or pure water. The peak gas consumption rate was 2.3 times that of the THF system. The hydrate formation efficiency was improved by including both THF and SDS, which maximized both the hydrate formation rate and total gas uptake.

One cause of the excellent hard‐tissue compatibility of Ti and Ti alloys compared with other metals is their ability to form calcium phosphate in biological environments. This is confirmed by many studies, although the formation mechanism has not been completely elucidated. In this study, to elucidate the initial formation kinetics of calcium phosphate on Ti in the human body, Ti was immersed in a simulated body fluid, Hanks' solution, for 100–106 s, followed by precise characterization using XPS. Ti specimens immersed in diluted Hanks' solutions were also characterized. The results reveal that phosphate ions are preferentially adsorbed and are incorporated onto the Ti surface in 100–102 s. This reaction is slow, and the apparent thickness of the surface layer is almost constant as 5.2 nm until 102 s. However, both calcium and phosphate ions are then rapidly incorporated, and calcium phosphate is formed after 103 s. The amounts of both calcium and phosphate increase with the logarithm of time because calcium and phosphate ions react directly with the Ti surface until 105 s. Other elements contained in Hanks' solution are not incorporated, calcium phosphate being formed preferentially. The incorporation of calcium is faster than that of phosphate, and the [Ca]/[P] ratio increases with the logarithm of time after 103 s. However, the chemical state of surface oxide film itself on Ti does not changed by immersion in Hanks' solution. The formation kinetics of calcium phosphate on Ti in a simulated body fluid are clearly revealed by this study. [ABSTRACT FROM AUTHOR]

Environmental context: Dimethyl trisulfide (DMTS) is a malodorous compound formed from decomposing algal matter and can severely compromise the quality of drinking water. The reactivity of DMTS toward cyanide was studied in aqueous solutions at environmentally relevant conditions. It was found that the half-lives of DMTS in the presence of free cyanide varied from several months to several thousand years depending on environmental conditions. Organically bound sulfur in the form of mono-, di- and polysulfide bridges constitutes a significant fraction of this element in recent and ancient sediments. In water columns of lakes, the concentrations of organo-sulfur compounds are much lower, and they are present in the form of malodorous dimethyl polysulfides. Currently, information regarding reactivity of organic polysulfides towards nucleophiles that are stronger than hydroxyl anions is lacking. In this work, the reaction kinetics of dimethyl trisulfide (DMTS) with the strong nucleophile and important environmental pollutant cyanide as a function of concentrations of reactants, pH and temperature were studied. It was found that the reaction rate constant as well as the activation energy of the reaction strongly depend on pH. The experimental data agree well with the existence of two distinct pathways: slow reaction between protonated cyanide and DMTS under acidic and neutral conditions and fast reaction between cyanide anion and DMTS under highly alkaline conditions. However, reactions of DMTS with the iron cyanide complexes hexacyanoferrate(ii) and hexacyanoferrate(iii) have no environmental significance since they are slower than the rate of DMTS decomposition. Under environmentally relevant conditions, rates of reactions of free cyanide with DMTS will be lower than the reaction with inorganic polysulfides or tetrathionate, but faster than the reaction with thiosulfate. Examples of application of kinetic parameters for calculation of rates of cyanide consumption in industrial and non-polluted natural aquatic systems as well as a protocol for quantification of organic polysulfide sulfur based on reaction with cyanide are provided. Environmental context. Dimethyl trisulfide (DMTS) is a malodorous compound formed from decomposing algal matter and can severely compromise the quality of drinking water. The reactivity of DMTS toward cyanide was studied in aqueous solutions at environmentally relevant conditions. It was found that the half-lives of DMTS in the presence of free cyanide varied from several months to several thousand years depending on environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract Background In recent years, formaldehyde is reported to be widely used as a food preservative to increase the shelf life of fruits and fishes in tropical countries. Formaldehyde is detrimental to human health. Hence, use of formaldehyde as a food preservative is legally prohibited in most of the countries. To regulate formaldehyde application in foods, the regulatory bodies often conduct on-the-spot analytical tests to detect artificially added formaldehyde in food items. However, formaldehyde is ubiquitous in the environment and is present in many animal and plant species as a product of their normal metabolism. This naturally occurring formaldehyde may interfere in the detection of artificially added formaldehyde in foods. It is, therefore, important to study the concentration and formation mechanism of naturally occurring formaldehyde in food items. Results In this study, the formaldehyde contents of food samples were determined using spectrophotometric technique. The naturally occurring formaldehyde contents of a wide range of fruit, vegetable, milk, poultry, mutton and meat samples were determined. In addition, formaldehyde contents of processed food items, such as: cooked beef and poultry, beverages, and commercially available UHT milk and powdered milk samples, were also assessed and analyzed. The naturally occurring formaldehyde contents of fruit, vegetable, milk, poultry, mutton and meat samples were found up to 58.3, 40.6, 5.2, 8.2, 15.2 and 8.5 ppm, respectively. Formaldehyde contents of commercially available UHT milk, powdered milk, beverages, cooked beef and poultry were found up to 187.7, 194.1, 21.7, 4.3 and 4.0 ppm, respectively. This study also analyzed the time dynamic behavior of the formation of endogenous formaldehyde content of banana (AAB genome of Musa spp.), mandarin and beef. Conclusions The experimental results provide a baseline data of natural occurring formaldehyde content of the analyzed food items. The formation behavior of formaldehyde may vary according to food types, storage temperature, storing time, and aging pattern of the food items. The findings of this study will be useful for the consumers, researchers, legal authorities and other stakeholders working on food safety and preservation.

Silicon nanocrystals (Si-NC) in silicon oxide is a promising material for many applications in micro- and nanoelectronics. This article develops a theory of the kinetics of Si-NC formation when there are both diffusion and reaction mechanisms of their formation. The theoretical expressions obtained for changing the concentration of nanocrystals and silicon implanted in oxide and their sizes are consistent with experimental results and can be used to optimize the formation conditions of technological processes of Si-NC formation. An important modern problem is the doping of nanocrystals with impurities, which allows the creation of silicon Si-NC–emitting light, and are also objects for solar energy. We have shown that nanocrystals with sizes less than 5 nm are limited by the potential barrier that creates surface tension. Thermodynamic calculations showed that there is a critical size of the Si-NC and if it is smaller, then it is impossible to introduce an impurity into it. These calculations were performed for doping silicon with phosphorus and tin. [ABSTRACT FROM AUTHOR]

The mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al2O3-Na2O system during the high-temperature sintering process were systematically investigated using DSC-TG, XRD, SEM-EDS, FTIR, and Raman spectra, and the crystal structure of Na4Ca3(AlO2)10 was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na4Ca3(AlO2)10, CaOAl2O3, and 12CaO·7Al2O3, and the content of Na4Ca3(AlO2)10 could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na4Ca3(AlO2)10 occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na4Ca3(AlO2)10 was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na4Ca3(AlO2)10 was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol. [ABSTRACT FROM AUTHOR]

We describe gas flow through the hydrate stability zone as a growing gas network with hydrate forming on its edges. The diffusion‐limited model successfully describes the dynamics of hydrate formation observed experimentally. We obtain an expression for the rate of hydrate growth in a region where gas and water coexist. Our modeled rate of hydrate formation is much lower than predicted with a kinetics‐based approach, and it more successfully simulates the hydrate formation rate observed in geologic systems. Current simulation approaches can readily incorporate our approach to describe hydrate formation in geological systems. Plain Language Summary: Methane hydrate is an ice‐like solid composed of methane gas and water. Hydrate is present on the Earth where methane and water come together at the correct geologic conditions—high pressure and near‐freezing temperature—which exist in the polar subsurface and in deep sea sediments. If the conditions are met, it is assumed that methane will only be present in hydrate form, yet free methane gas is often found flowing through this zone in the field and laboratory. To explain these observations, we envision a system where the hydrate provides a barrier between the methane gas and water in sediments. In this model, hydrate formation is limited by the rate at which methane can diffuse across the solid hydrate. When calibrated with one parameter, the model fits well with multiple field and laboratory observations of hydrate formation in sediments. Key Points: Gas flow within the hydrate stability zone is accompanied by the formation of a hydrate shell at the gas‐water interfaceWe model gas flow within the hydrate stability zone as an invasion percolation process coupled with hydrate formationOur upscaled model produces hydrate formation rates similar to those observed in nature and slower than existent kinetic models [ABSTRACT FROM AUTHOR]

Hydrate-based H 2 purification, taking advantage of the different phase-equilibrium characteristics exhibited by H 2 and impurity gases, presents a potential technological avenue with considerable implications for engineering-oriented pursuits. This review encompasses critical aspects relating to H 2 gas purification techniques, including a rigorous comparative analysis between established H 2 purification approaches and the hydrate-based method. Hydrate-based H 2 purification has the advantage of having a low cost of raw materials, but the harsh thermodynamic and kinetic conditions of hydrate formation have hindered the development of this technology. Researchers are endeavoring to devise solutions for these challenges by exploring aspects such as hydrate crystal microstructure, hydrate thermodynamics, kinetics, and more. An extensive investigation has been conducted into the microstructure of H 2 -involved hydrate, coupled with an examination of the thermodynamics governing the hydrate phase equilibrium. It is suggested that the prudent selection of an appropriate additive type and concentration, balancing hydrate formation conditions and impurity gas occupancy, is paramount. Furthermore, the kinetics properties of hydrate nucleation, formation, and H 2 purification are summarized. Although additives, the physical method, and synergistic approaches demonstrated a notable enhancement in kinetic performance, the associated expenditure was overlooked inadvertently. The primary objective of this review is to facilitate a comprehensive understanding of the advances and challenges in H 2 purification, focusing prominently on the hydrate-based method as the forefront of investigation. [Display omitted] • An overview of progress and challenges in hydrate-based H 2 purification is provided. • Hydrate structure, thermodynamics, kinetics, and additive selection are discussed. • Microstructure of the H 2 -involved hydrate is important to purification. • Selection of an appropriate additive type and concentration is paramount. [ABSTRACT FROM AUTHOR]

The kinetic characteristics governing methane conversion into solid hydrates within seabed sediments influence hydrate accumulation and resource distribution, which is significant for the evaluation of global natural gas hydrate reserves and the implication of hydrate development. However, the influence of sediment particle size on methane hydrate formation kinetics remains unclear. In this study, simulating in situ conditions of the seafloor, the kinetics behaviors of CH 4 hydrate formation within saline porous sediments were investigated. The experimental results indicate that the methane hydrate formation rate does not exhibit a strictly unidirectional change with changed quartz sand particle size. The unidirectionality and magnitude of hydrate formation rate change are simultaneously influenced by both quartz sand particle size and water saturation levels. The different effective gas-liquid contact area is the primary factor underlying the occurrence of these phenomena. However, for more porous clay sediments with greater specific surface area, the theory of effective gas-liquid contact area becomes inapplicable. The addition of clay to quartz sand sediment inversely inhibits the methane hydrate formation, which is caused by water absorption. This work can advance the comprehension of the intricate interplay between hydrate growth kinetics and the attributes of sedimentary hosts. • CH 4 hydrate formation rate does not exhibit a strictly unidirectional change with varying quartz sand particle size. • The unidirectionality of hydrate formation rate change are simultaneously influenced by particle size and water saturation. • Effective gas-liquid contact area determines hydrate formation rate rather than quartz sand particle size. • The inherent water-absorbing quality of porous clay instead results into reduced CH 4 hydrate formation kinetics. [ABSTRACT FROM AUTHOR]

Among the complexes of porphyrins, special attention has been paid to those possessing out-of-plane (OOP) structures, for the formation of which the size, as well as the coordinative character of the metal center are responsible. In these coordination compounds, the central atom cannot fit coplanarly into the cavity of the ligand, hence, it is located above the porphyrin plane, distorting it. Equilibria and kinetics of the complex formation, spectrophotometric, photophysical and primary photochemical properties of post-transition and lanthanide OOP metalloporphyrins were investigated, in addition electronic structural calculations were performed; hence, the general OOP characteristics were determined.Meanwhile, few doubtful questions have attempted to be answered concerning the categorization of metalloporphyrins, the borderline case complexes and hyperporphyrins.

As human society has advanced, nuclear energy has provided energy security while also offering low carbon emissions and reduced dependence on fossil fuels, whereas nuclear power plants have produced large amounts of radioactive wastewater, which threatens human health and the sustainability of water resources. Here, we demonstrate a hydrate-based desalination (HBD) technology that uses methane as a hydrate former for freshwater recovery and for the removal of radioactive chemicals from wastewater, specifically from Cs- and Sr-containing wastewater. The complete exclusion of radioactive ions from solid methane hydrates was confirmed by a close examination using phase equilibria, spectroscopic investigations, thermal analyses, and theoretical calculations, enabling simultaneous freshwater recovery and the removal of radioactive chemicals from wastewater by the methane hydrate formation process described in this study. More importantly, the proposed HBD technology is applicable to radioactive wastewater containing Cs + and Sr 2+ across a broad concentration range of low percentages to hundreds of parts per million (ppm) and even subppm levels, with high removal efficiency of radioactive chemicals. This study highlights the potential of environmentally sustainable technologies to address the challenges posed by radioactive wastewater generated by nuclear technology, providing new insights for future research and development efforts.

Abstract—This paper is devoted to determining the kinetic regularities of the formation of surface antifriction films in refined sunflower oil. IR ATR spectroscopy revealed that the main chemical reactions leading to antifriction film formation occur on the friction surface in the first 20 s after the start of tribological tests. It was established experimentally that the C=C bonds of fat molecules do not participate in the formation of the antifriction film. The main changes in the IR spectra of the antifriction film compared to the original oil are a decrease in the intensity of C=O bond vibrations and an increase in the intensity of C–H bond vibrations. This indicates that the film is not a product of oxidation and subsequent drying of the oil. [ABSTRACT FROM AUTHOR]

To promote the heat and mass transfer during the hydrate formation process, an internal spiral‐grooved tube (ISGT) was proposed as the reaction tube in a large‐scale multi‐tube bubble column reactor with external slurry circulation. In order to investigate such multi‐component gas (natural gas)‐water‐surfactant systems during the hydrate formation process in the ISGT, based on the solute permeation model and Kolmogorov isotropic turbulence theory, a CFD method combined with the population balance model (PBM) was utilized to simulate gas‐liquid mass transfer coefficient. Then, the hydrate formation kinetics model in ISGT was modelled based on the model proposed by Kashchiev and Firoozabadi. The hydrate formation experiments were carried out in the multi‐tube bubble column reactor at six different pressure‐temperature‐circulating flow velocities of piston pump regimes to investigate the actual formation process of natural gas hydrate. The experimental results were then used to finetune the optimized parameters to facilitate accurate model predictions. [ABSTRACT FROM AUTHOR]

In this study, the phase evolution and formation kinetics of (Fe,Cr)7C3/Fe surface composite were investigated. The formation process of (Fe,Cr)7C3/Fe surface composite involves through the formation of a dense ceramic layer, short rod-like (Fe,Cr)7C3 particulates, and disappearance of the dense ceramic layer. The mathematical model was applied to study the formation kinetics of (Fe,Cr)7C3/Fe surface composite by considering the impact of heat treatment temperature and time. The results revealed a parabolic relationship between the thickness of composite layer and heat treatment time, indicating that the formation kinetics of the composite layer was governed by diffusion. The proposed formation kinetics model shows a good agreement with the experimental data. The growth rate constant of composite layer and the reaction temperature satisfy Arrhenius relationship. The activation energy for the growth of composite layer was found to be 208.68 kJ/mol. [ABSTRACT FROM AUTHOR]

Summary: The formation of two toxic aldehydes, 4‐hydroxyhexenal (HHE) and 4‐hydroxynonenal (HNE) were monitored in five vegetable oils during thermal processing (100–200 °C) with the results modelled. HHE was only determined in rapeseed and linseed oil, while HNE was determined in all tested oils and the contents varied significantly depending on the oil type. For HHE/HNE‐detected oils, the evolution during heating was well described by the pseudo‐first‐order kinetic model. The equilibrium contents of HHE/HNE increased and the duration until equilibrium decreased as a function of temperature. The calculated reaction rate constants followed the Arrhenius law. The formation rate of HHE/HNE was remarkably oil‐dependent, which was also in accordance with the calculated kinetic and thermodynamic parameters. Accordingly, the above results can contribute to a prediction of HHE/HNE formation in different vegetable oils during thermal processing, especially the temperature/time required during frying, which is generally higher than 100 °C and 6 h., respectively. [ABSTRACT FROM AUTHOR]