Carbamate Formation Research Articles

Ethyl Carbamate in Fermented Food Products: Sources of Appearance, Hazards and Methods for Reducing Its Content.

Ethyl carbamate, the ethyl ester of carbamic acid, has been identified in fermented foods and alcoholic beverages. Since ethyl carbamate is a probable human carcinogen, reduction of its content is important for food safety and human health. In alcoholic beverages, ethyl carbamate is mostly formed from the reaction of ethanol with urea, citrulline and carbamyl phosphate during fermentation and storage. These precursors are generated from arginine metabolism by wine yeasts and lactic acid bacteria. This review summarizes the mechanisms of ethyl carbamate formation, its impact on human health and methods used in winemaking to minimize its content. These approaches include genetic modification of Saccharomyces cerevisiae wine strains targeting pathways of arginine transport and metabolism, the use of lactic acid bacteria to consume arginine, direct degradation of ethyl carbamate by enzymes and microorganisms, and different technological methods of grape cultivation, alcoholic fermentation, wine aging, temperature and duration of storage and transportation.

Effects of pressure and temperature on CO2 facilitation of amino acid salt-containing membranes for post-combustion carbon capture

Polymeric facilitated transport membranes (FTMs) that contain amino acid salts (AASs) provide a cost-effective option for reducing the CO2 emissions associated with burning fossil fuels. In the current work, we examined the effects of CO2 partial pressure and temperature on the CO2 absorption properties of three AAS mobile carriers, piperazine glycinate (PZ-Gly), 2-(1-piperazinyl)ethylamine glycinate (PZEA-Gly), and 2-(1-piperazinyl)ethylamine sarcosinate (PZEA-Sar), and their facilitation of CO2 transport by employing 13C NMR spectroscopy. The CO2 loading and the distribution of reaction products, i.e., carbamate and bicarbonate products, were analyzed and quantified for each AAS sample. The 13C NMR analysis revealed that PZEA-Sar had a greater CO2 loading and favored the more efficient bicarbonate pathway in comparison to PZ-Gly and PZEA-Gly. In addition, we noted marked differences in the formation of carbamate and bicarbonate products when the CO2 partial pressure and temperature were adjusted. The concentration gradient of the reaction products formed indicated that the diffusion of carbamate products was the most influential factor in CO2 transport under reduced CO2 partial pressure. However, as the partial pressure of CO2 increased, bicarbonate products began to play a more significant role. At elevated temperatures, a lower absorption of CO2 was observed, resulting in the reduced generation of both reaction products. This suggests that the enhanced CO2 permeance of FTMs is mainly attributed to the accelerated diffusion of the reaction products. The findings of this study contribute to a comprehensive understanding of the transport mechanism by which AAS carriers enhance CO2 facilitation, allowing for the refinement of more efficient FTM designs.

Speciation and gas-liquid equilibrium study of CO2 absorption in aqueous MEA-DEEA blends

The blending of primary amines, with fast reaction kinetic, together with tertiary amines, with a large loading capacity, is an increasingly popular approach to develop high-performance CO2 capture sorbents with low energy requirements for regeneration. In this study, we investigated the CO2 absorption performance of several aqueous solutions obtained by mixing ethanolamine (MEA) and diethylethanolamine (DEEA) and compared them with that of individual MEA and DEEA. CO2 loadings at equilibrium were measured experimentally under a wide range of operating conditions, at temperatures between 298 and 323 K, CO2 partial pressures in the range 5–60 kPa, and different amine mixing ratios. In addition, 13C NMR spectroscopy was employed to elucidate the reaction mechanisms and identify the species formed during CO2 capture. The results of the study reveal the intricate interplay of MEA and DEEA in CO2 capture, where MEA carbamate formation predominates in the early stages, gradually shifting to bicarbonate formation as the amine concentration decreases. Moreover, excess properties, which reflect non-ideal behaviors in amine blends, were introduced as a key parameter in the study. An excess property model, based on excess CO2 loading, was developed to accurately predict the CO2 equilibrium solubility without constant experimental measurement. As a result, good agreement was found between the experimental data and those calculated with the model (excess CO2 loading) under the same operating conditions, with a average relative deviation of 1.1%.

CO2 Capture and Release in Amine Solutions: To What Extent Can Molecular Simulations Help Understand the Trends?

Absorption in amine solutions is a well-established advanced technology for CO2 capture. However, the fundamental aspects of the chemical reactions occurring in solution still appear to be unclear. Our previous investigation of aqueous monoethanolamine (MEA) and 2-amino-2-methyl-1,3-propanediol (AMPD), based on ab initio molecular dynamics simulations aided with metadynamics, provided new insights into the reaction mechanisms leading to CO2 capture and release with carbamate formation and dissociation. In particular, the role of water-strongly underestimated in previous computational studies-was established as essential in determining the development of all relevant reactions. In this article, we apply the same simulation protocol to other relevant primary amines, namely, a sterically hindered amine (2-amino-2-methyl-1-propanol (AMP)) and an aromatic amine (benzylamine (BZA)). We also discuss the case of CO2 capture with the formation of bicarbonate. New information is thus obtained that extends our understanding. However, quantitative predictions obtained using molecular simulations suffer from several methodological problems, and comparison among different chemical species is especially demanding. We clarify these problems further with a discussion of previous attempts to explain the different behaviors of AMP and MEA using other types of models and computations.

Magnetic amyloid-based biocatalyst for the hydrolysis of urea

The presence of urea in wines and other alcoholic beverages represents a critical problem since it can chemically react with ethanol, which leads to the formation of ethyl carbamate, a carcinogenic agent according to the World Health Organization. Here we report the creation of a biocatalyst for the hydrolysis of urea, which could potentially be used before bottling alcoholic drinks. For this, the effective surface area of streptavidin-labeled magnetic microparticles was amplified by functionalization with biotin-labeled hen egg lysozyme amyloid fibers. Subsequently, by using copper and hydrogen peroxide induced cross-linking of unmodified proteins (CHICUP), soybean urease was immobilized to the fibers. This gave rise to a magnetic biocatalyst with remarkable urease activity, which was maintained even after 10 reuses. We propose that this strategy could be used as a platform for immobilizing other molecules to design and develop a myriad of biocatalysts for the food industry.

Interactive adsorption mechanism and product distribution of impurity gases on CO2 adsorption over amine-grafted ZSM-5/SBA-16 adsorbent

Solid amine adsorbents hold promising application prospects in the realm of industrial flue gas decarbonization. Nevertheless, there remains a need for substantial improvement in the cycling stability of solid amine adsorbents. Additionally, the competitive adsorption mechanism of solid amine adsorbents pertaining to flue gas components lacks thorough verification. In this study, amine-grafted micro-mesoporous ZSM-5/SBA-16 adsorbents were synthesized to improve the CO2 adsorption capacity and investigate the effect of impurity gases on CO2 adsorption. Various characterization techniques, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption, and elemental analysis, were employed to analyze the properties of the adsorbents. The loading analysis of the micro-mesoporous molecular sieve revealed that ZS-A-2.0 exhibited the highest CO2 adsorption capacity of 41.39 mg/g. Mass spectrometry was utilized to evaluate the co-adsorption experimentation involving multicomponent gases. The breakthrough curves of CO2 displayed dual stages at low concentrations, suggesting the simultaneous occurrence of physical and chemical adsorption throughout the entire adsorption process. Based on temperature programming desorption (TPD) and in situ Fourier transform infrared spectroscopy (FTIR), the results indicated a notable enhancement in CO2 adsorption due to the presence of H2O. Conversely, the presence of SO2 and NO exhibited adverse effects on CO2 adsorption, consequently hindering the formation of carbamate and (RNH3)2CO3 adsorption products. This study presents, for the first time, a comprehensive investigation into the interactive adsorption mechanism and product distribution between CO2 and impurity gases. The findings presented herein provide valuable insights and essential support for practical flue gas applications.

Modified Achira (Canna edulis) starch-based adhesives: effect of acid hydrolysis and urea derivatization on physicochemical properties

In recent decades, due to high market demand and multiple environmental concerns, attention has been focused on the use of starch as renewable raw material for adhesives elaboration. Particularly, the origin and film-forming properties of Achira (Canna edulis) starch make it a potential representative for the development of bioadhesives. In this study, achira starch modified by acid hydrolysis and subsequent derivatization with urea was used to prepare adhesives for plywood substrates. For this purpose, the modified starch and polyvinyl alcohol (PVA) were used to prepare several formulations with different proportions of components. Afterwards, they were characterized in terms of physicochemical and mechanical properties. The formation of starch carbamates was confirmed not only by the results of nitrogen content, but also by infrared spectroscopy through the presence of N-H and C=O groups. On the other hand, viscosity increased with PVA content due to the interaction of hydroxyl groups, while starch had the opposite effect. Shear strength showed higher values at higher concentrations of PVA and starch. From the perspective of mechanical behavior, the results showed similarities with a commercial adhesive based on polyvinyl acetate (PVAc), as well as with other bio-based adhesives from studies conducted under comparable conditions.

Elucidating the Molecular Mechanism of CO2 Capture by Amino Acid Ionic Liquids.

Amino acid ionic liquids have received increasing attention as ideal candidates for the CO2 chemisorption process. However, the underlying molecular mechanisms, especially those involving proton transfer, remain unclear. In this work, we elucidate the atomistic-level reaction mechanisms responsible for carbamate formation during CO2 capture by amino acid ionic liquids through explicit ab initio molecular dynamics augmented by well-tempered metadynamics. The resulting ab initio free-energy sampling reveals a two-step reaction pathway in which a zwitterion, initially formed from the reaction between the anion of serine and CO2, undergoes a kinetically facile intermolecular proton transfer to the O atom of the COO- moiety in the nearby serine. Further analysis reveals that the significantly reduced free-energy barriers are attributed to enhanced intermolecular interaction between the zwitterion and serine, thus facilitating the kinetic favorability of the proton transfer, which governs the overall CO2 capture mechanism. This work provides valuable insight into the important mechanistic and kinetic features of these reactions from explicit condensed phase ab initio MD free-energy sampling of the CO2 capture process.

Inferring the Energetics of CO2-Aniline Adduct Formation from Vibrational Spectroscopy.

Control of atmospheric CO2 is an important contemporary scientific and engineering challenge. Toward this goal, the reaction of CO2 with amines to form carbamate bonds is an established method for CO2 capture. However, controllable reversal of this reaction remains difficult and requires tuning the energetics of the carbamate bond. Through IR spectroscopy, we show that a characteristic frequency observed upon carbamate formation varies as a function of the substituent's Hammett parameter for a family of para-substituted anilines. We present computational evidence that the vibrational frequency of the adducted CO2 serves as a predictor of the energy of formation of the carbamate. Electron donating groups typically enhance the driving force of carbamate formation by transferring more charge to the adducted CO2 and thus increasing the occupancy of the antibonding orbital in the carbon-oxygen bonds. Increased occupancy of the antibonding orbital within adducted CO2 indicates a weaker bond, leading to a red-shift in the characteristic carbamate frequency. Our work serves the large field of CO2 capture research where spectroscopic observables, such as IR frequencies, are more easily obtainable and can stand in as a descriptor of driving forces.

A Bifunctional Ionic Liquid for Capture and Electrochemical Conversion of CO2 to CO over Silver.

Electrochemical conversion of CO2 requires selective catalysts and high solubility of CO2 in the electrolyte to reduce the energy requirement and increase the current efficiency. In this study, the CO2 reduction reaction (CO2RR) over Ag electrodes in acetonitrile-based electrolytes containing 0.1 M [EMIM][2-CNpyr] (1-ethyl-3-methylimidazolium 2-cyanopyrolide), a reactive ionic liquid (IL), is shown to selectively (>94%) convert CO2 to CO with a stable current density (6 mA·cm-2) for at least 12 h. The linear sweep voltammetry experiments show the onset potential of CO2 reduction in acetonitrile shifts positively by 240 mV when [EMIM][2-CNpyr] is added. This is attributed to the pre-activation of CO2 through the carboxylate formation via the carbene intermediate of the [EMIM]+ cation and the carbamate formation via binding to the nucleophilic [2-CNpyr]- anion. The analysis of the electrode-electrolyte interface by surface-enhanced Raman spectroscopy (SERS) confirms the catalytic role of the functionalized IL where the accumulation of the IL-CO2 adduct between -1.7 and -2.3 V vs Ag/Ag+ and the simultaneous CO formation are captured. This study reveals the electrode surface species and the role of the functionalized ions in lowering the energy requirement of CO2RR for the design of multifunctional electrolytes for the integrated capture and conversion.

Energy efficient CO2 capture in dual functionalized ionic liquids and N-methyldiethanolamine solvent blend system at elevated pressures: Interaction mechanism and heat duties

In this study, three lab synthesized dual functionalized ionic liquids (DFILs) were utilized as promoters to improve the CO2 absorption performance of methyl diethanolamine (MDEA) absorbent under elevated pressures of 2–7 bar. Initially, 5 wt% DFILs containing polyamine cations (triethylenetetramine and diethylenetriamine) and cyclic amine anions (piperazine and imidazole) were blended with 20 wt% MDEA and their physical and chemical properties were examined. The pKa value at 303 K of the blend of [TETAH][Pz] + MDEA is found to be 9.83, which is nearly equal to the industrial 30 wt% monoethanolamine (MEA) solution. The CO2 absorption performance at different temperatures and pressures demonstrated that the blending of 5 wt% DFILs into aqueous MDEA significantly altered both the absorption rate and loading. The percentage loading showed a significant 22% increase in the [TETAH][Pz] promoted aqueous MDEA blend. This is attributed to the high amount of carbamate and bicarbonate formation in the DFILs blended aqueous MDEA as revealed by 13C NMR results. These results were possible due to the highly reactive piperazine anion being a crucial factor in the significant performance of the [TETAH][Pz] blend system. Further, when the regeneration heat duty of all these absorbents was calculated, it was found that MDEA and DFILs blended MDEA absorbents consumed 25.36% and 33.34–22.79% less energy than industrial MEA, respectively along with a low absorbent loss during regeneration thus, [TETAH][Pz] and [TETAH][Im] are potential promoters in an aqueous MDEA solvent system for pressurized capture of carbon dioxide.

Front Cover: A Tunable Colorimetric Carbon Dioxide Sensor Based on Ion‐Exchanger‐ and Chromoionophore‐Doped Hydrogel (Anal. Sens. 6/2023)

The cover feature image shows a two-dimensional (2D) colorimetric carbon dioxide (CO2) sensor composed of a gas-permeable polypropylene film (25 μm thick) and a signal transduction hydrogel layer (30 μm thick). The hydrogel layer contained a pH sensitive chromoionophore to indicate the CO2 induced pH change, and a cationic amine to further capture CO2 through the carbamate formation reaction. With this 2D colorimetric CO2 optode, the CO2 release from yeast-catalyzed flour fermentation was successfully monitored. More information can be found in the Research Article by Jingying Zhai, Xiaojiang Xie, and co-workers.

CO2 absorption in blended amine solvent: Speciation, equilibrium solubility and excessive property

Mixing different amines is a common method to develop better solvents for CO2 capture. As the mixing provides more adjustability on the solvent properties, it introduces complex interaction between dissimilar amine molecules who may perform diverse role in the reactions. Here we studied CO2 absorption in monoethanolamine (MEA), methyldiethanolamine (MDEA) and their mixtures thereof. The speciation profiles along with CO2 loading were provided via NMR to reveal the competition/coordination of MEA and MDEA in participating the key reactions that drove CO2 absorption (i.e. carbamate formation and amine protonation). Furthermore, the CO2 loading of the solvents were measured under equilibrium for various temperature, CO2 partial pressure. The excessive CO2 loading was firstly introduced to analyze the loading data regarding the solvent composition. Accordingly, an excessive property model was applied for data correlation. The calculated CO2 loading agreed well with experimental data with average absolution relative deviation of 1.7%.

Impact of carbamate formation on the surface tension of epoxy‐amine curing systems

AbstractEpoxy‐amine reactive systems, including their surface tension, have been studied due to their use and importance in composites and adhesives in laboratory and industrial applications. Understanding how the system's surface tension changes during curing could help target applications for tailored composites. Using the Wilhelmy plate method, surface tensions for epoxy‐curing agent systems were investigated under different environments. While the epoxy exhibited an expected negative temperature coefficient of −0.096 mN/m/°C, the curing agent exhibited a positive temperature coefficient of 0.073 mN/m/°C, which is due to the curing agent reacting with atmospheric CO2 to form carbamate through a zwitterion pathway and functional groups accumulating at the surface of the reacting systems. Carbamate formation results in a surface tension below that of the individual constituents in the epoxy‐amine curing agent system. Fourier transform infrared (FTIR) spectroscopy was used to verify in situ formation of carbamate, and by reducing the system's temperature, it was demonstrated that the system surface tension profiles displayed micellar surfactant‐like characteristics. FTIR was used to explore the difference in composition between the surface and the bulk, in particular carbamate formation at the surface, resulting in a lowering of the surface tension of reacting systems.

Oxidative cross dehydrogenative coupling directed carbamates synthesis using Cu(II) pincer complex as active catalyst under mild reaction condition

AbstractDevelopment of an air‐stable and cheap transition metal‐based catalyst for the formation of carbamates via the cross‐coupling reaction of various 2‐carbonyl substituted phenolic derivatives or 1,3‐diketo derivatives with N,N‐disubstituted formamides (C(sp2)O bond formation) under mild conditions is the key focus of synthetic chemists. In this context, we have developed a novel benzothiazole appended 2,6‐di picolinamide‐based Cu(II) complex for the facile generation of carbamates at a slightly elevated temperature (50°C) with a short reaction time and low catalyst loading (0.5 mol%) for the first time. The synthesized complex was well characterized by ultraviolet–visible, infrared, electron paramagnetic resonance spectroscopy, cyclic voltammetry, high‐resolution mass spectrometry (HRMS), as well as by single crystal X‐ray diffraction analysis. A wide range of aromatic carbamates was synthesized using complex 1 in good/excellent yield with decent functional group tolerance under mild conditions. Control experiments suggest that the reaction proceeds via the radical mechanism, and the formation of radical‐mediated intermediates was confirmed by the gas chromatography (GC), GCMS and HRMS. The use of low cost and environmentally benign catalysts in mild conditions along with the tolerance of a wide range of functional groups makes this an easy synthetic approach for the development of carbamates.

Enhancement of the aromatic alcohols and health properties of Chinese rice wine by using a potentially probiotic Saccharomyces cerevisiae BR14

In recent years, potential probiotic strains have been increasingly applied to food to promote consumer health or improve the nutrition of products. In current study, a potential probiotic Saccharomyces cerevisiae strain BR14 was applied for the development of functional Huangjiu. The strain significantly increased the ethanol content in final wine, as well as the total acidity, especially acetic acid and lactic acid. As an accessory starter, BR14 promoted the formation of total volatile flavor compounds, particularly in 1-propanol, 3-methyl-1-butanol and phenethyl alcohol. Meanwhile, it reduced the formation of 2-Methyl-1-propanol by 54.65%. Regarding nutrients and functionality of final Chinese rice wine, S. cerevisiae BR14 exhibited excellent capacity in the improvement of glutamic acid, ornithine and antiradical activity for wine production. Content of urea, which determined the formation of ethyl carbamate, considerably decreased by the co-fermentation of BR14. Moreover, polysaccharide of Huangjiu fermented by BR14 stimulated the proliferation of macrophages RAW264.7, and reduced anti-inflammatory response. Based on sensory evaluation, BR14 wine was highly assessed for its intensive levels in alcohol-aroma and full body. This study verified the biofunctions of BR14, indicating the possibility to apply potential probiotic yeasts in food applications.

Support Pore Structure and Composition Strongly Influence the Direct Air Capture of CO2 on Supported Amines.

A variety of amine-impregnated porous solid sorbents for direct air capture (DAC) of CO2 have been developed, yet the effect of amine-solid support interactions on the CO2 adsorption behavior is still poorly understood. When tetraethylenepentamine (TEPA) is impregnated on two different supports, commercial γ-Al2O3 and MIL-101(Cr), they show different trends in CO2 sorption when the temperature (-20 to 25 °C) and humidity (0-70% RH) of the simulated air stream are varied. In situ IR spectroscopy is used to probe the mechanism of CO2 sorption on the two supported amine materials, with weak chemisorption (formation of carbamic acid) being the dominant pathway over MIL-101(Cr)-supported TEPA and strong chemisorption (formation of carbamate) occurring over γ-Al2O3-supported TEPA. Formation of both carbamic acid and carbamate species is enhanced over the supported TEPA materials under humid conditions, with the most significant enhancement observed at -20 °C. However, while equilibrium H2O sorption is high at cold temperatures (e.g., -20 °C), the effect of humidity on a practical cyclic DAC process is expected to be minimal due to slow H2O uptake kinetics. This work suggests that the CO2 capture mechanisms of impregnated amines can be controlled by adjusting the degree of amine-solid support interaction and that H2O adsorption behavior is strongly affected by the properties of the support materials. Thus, proper selection of solid support materials for amine impregnation will be important for achieving optimized DAC performance under varied deployment conditions, such as cold (e.g., -20 °C) or ambient temperature (e.g., 25 °C) operations.

Theoretical Assessment of Carbon Dioxide Reactivity in Methylpiperidines: A Conformational Investigation.

In this work, the possible mechanisms for the reactions of CO2 with various positional isomers of methylpiperidines (MPs) (N-MP, 2-MP, 3-MP, and 4-MP) including the effect of aqueous solvation have been explored using quantum chemical methods. The major pathways investigated for CO2 capture in aqueous amines are carbamate formation, its hydrolysis, and the bicarbonate formation (CO2 + H2O + MP) reaction. The calculations indicate that an axial orientation for the methyl group and an equatorial for the COO- group could be energetically ideal in the carbamate product of MPs. The proton abstraction step in the carbamate pathway is almost barrierless for the zwitterion-amine route, while a much higher energy barrier is observed for the zwitterion-H2O route. During carbamate hydrolysis, the addition of even two explicit water molecules does not exhibit any notable effect on the already high energy barrier associated with this reaction. This indicates that bicarbonate formation is less likely to occur via carbamate hydrolysis. The calculations suggest that, although the carbamate pathway is kinetically favored, the MP carbamate could still be a minor product, especially for sterically hindered conformations, and the bicarbonate pathway should be predominant in aqueous MPs.

Trifluoroethanol-Mediated Cyclization of Two-Carbon-Tethered Epoxide–N-Boc Pairs: Completely Regioselective Synthesis of 3,6-Disubstituted 1,3-Oxazinan-2-ones

AbstractThe regio- and diastereoselective construction of biologically relevant cyclic carbamates under operationally simple and mild transition-metal-free conditions is challenging and has led to a demand for efficient methods for their synthesis. The intramolecular ring-opening cyclization of N-Boc-tethered epoxides leading to the formation of cyclic carbamates is equipped with many favorable synthetic features, including easy accessibility of starting materials in a stereodefined form, high diversification points in the substrates, and a favorable entropy factor. However, its use in the construction of 1,3-oxazinan-2-ones remains largely neglected. Specifically, prior to 2020, only few 1,3-oxazinan-2-ones were successfully synthesized using this strategy. Moreover, our very own recent attempt to access these heterocycles using one-carbon-tethered N-Boc–epoxide pairs was met with little success as the process furnished either only 1,3-oxazolidin-2-ones or nearly equal amounts of 1,3-oxazolidin-2-ones and 1,3-oxazinan-2-ones. Herein, we demonstrate that when the epoxide and N-Boc moieties are connected by a two-carbon tether, the cyclization could deliver 1,3-oxazinan-2-ones containing vicinal stereocenters, as sole regioisomers and diastereomers in high yields (up to 95% yield), irrespective of whether the distal epoxide substituent is alkyl or aryl, or the epoxide is cis- or trans-configured.

Simulation and Control of the Formation of Ethyl Carbamate during the Fermentation and Distillation Processes of Chinese Baijiu

Baijiu is a popular alcoholic beverage with a long history in China. However, the widespread presence of the ethyl carbamate (EC) carcinogen has raised many food safety concerns. To date, the main precursors of EC and its formation process have not been determined, resulting in difficulty controlling EC in Baijiu. In this study, the main precursors of EC are identified as urea and cyanide during the process of brewing for different flavors of Baijiu, while the dominant stage in which EC formation occurs is during the process of distillation rather than fermentation. In addition, the effects of temperature, pH value, alcohol concentration and metal ions on the formation of EC are confirmed. In the following study, the main precursor of EC is identified as cyanide during the process of distillation, and a combination of optimizing the distillation device and adding copper wire is proposed. Furthermore, the effect of this novel strategy is examined in gaseous reactions between cyanide and ethanol, reducing the concentration of EC by 74.0%. Finally, the feasibility of this strategy is verified in simulated distillations of fermented grains, reducing the formation of EC by 33.7-50.2%. This strategy has great application potential in industrial production.