Fe3O4 Surface Research Articles

Adsorption or deoxidation of H2 interacted with Fe3O4 surface under different H coverage: A DFT study

The adsorption and dissociation of H2, the migration ability of H atom, as well as the competition relationship between adsorption or deoxidation of H2 with increasing of H adsorption coverage on the Fe3O4 (1 1 1)-Fetet1 and (0 0 1)-B surfaces were systematically studied by DFT + U method. The adsorption energy and the optimal dissociation barrier of H2 on two Fe3O4 surface is about 0.04 eV and 1.0 eV, respectively. The surface O site is the most favorable adsorption site for H and the dissociated H2 is adsorbed on the adjacent surface O atoms. When H coverage is low, H preferentially adsorbs to the most stable O sites with the maximum adsorption heat. With the increasing of H coverage, the adsorption heat gradually decreases. When H coverage approaches saturated coverage, H2 reacted with surface O to form H2O become more favorable than direct adsorption. The phase diagrams of H adsorption/deoxidation at different temperature and pressure ranges were calculated. It can be found that the reduction of surface O become more favorable with the increasing of H coverage. The results indicate that the degree of reduction difficulty of surface O can be controlled by changing the coverage of H by adjusting the reaction condition.

Preparation of chitosan modified magnetic carbon nanotubes and application in immobilized enzymes

ABSTRACTChitosan (CTS) was selected to combine Fe3O4/CNTs with noncovalent bonds to prepare CTS modified magnetic carbon nanotubes (CTS-Fe3O4/CNTs). The chemical structure, morphology, crystal structure, element and magnetic properties were analyzed by means of FTIR, TEM, XRD, XPS and VSM. CTS-Fe3O4/CNTs was used as immobilized enzyme carrier for the degradation of phenolic compounds in sewage. The results of characterizations demonstrated that CTS had successfully modified the surface of Fe3O4/CNTs, amino groups existed simultaneously on the surface of Fe3O4 and CNTs. The surface modification of CTS did not destroy the crystal structure of Fe3O4/CNTs and CTS-Fe3O4/CNTs had super paramagnetic property. The effects of preparation and reaction conditions of CTS-Fe3O4/CNTs immobilized enzyme were investigated. Compared with free enzyme, the carrier CTS-Fe3O4/CNTs immobilized enzyme restricted conformational change of enzyme and stabilized enzyme relative activities, enhanced higher temperature tolerance, wider pH value, repeated using times and storage time under the optimum conditions of immobilized enzyme.

Bifunctional Au-Fe3O4 Nanoheterodimers Acting as X-ray Protector in Healthy Cells and as X-ray Enhancer in Tumor Cells.

Bifunctional Au-Fe3O4 nanoheterodimers were synthesized by thermally decomposing Fe(III)oleate on gold nanoparticles followed by functionalizing with tiron, 2,3-dihydroxybenzoic acid, or caffeic acid. These catechol derivatives are antioxidative and thus are predicted to function as superoxide scavengers. In particular, caffeic acid lost its antioxidant capacity, although it was covalently linked through its carboxyl moiety to the Fe3O4 surface. Tiron was shown to bind via its catechol group to the Au-Fe3O4 nanoheterodimers, and 2,3-dihydroxybenzoic was just physisorbed between the oleic acid surface structures. Caffeic-acid stabilized Au-Fe3O4 nanoheterodimers turned out to act as X-ray protector in healthy cells but as X-ray enhancing agents in cancer cells. Furthermore, these functionalized Au-Fe3O4 nanoheterodimers were found to inhibit the migratory capacity of the cancer cells.

Ab initio study on physical and chemical interactions at borates and iron oxide interface at high temperature

Ab initio molecular dynamics (AIMD) simulations were carried out to study the interactions of sodium tetraborate (Na2B4O7) and boron oxide (B2O3) on an iron oxide surface Fe2O3(0 0 0 1) at 1073 K. The results demonstrate that high temperature transforms Na2B4O7 structure by activating sodium mobility and decomposing BO4 complexes into BO3 and non-bridging oxygen. These products engage in chemical reactions with the Fe2O3 surface by forming O–Na ionic and Fe–O–B covalent bonds, which make Na2B4O7 adhere extremely well on the surface. Density profile and charge analysis show that sodium cations play a critical role at the interface by forming O–Na–O stacking and acting as a bridge to connect the negatively charged areas of the O-rich surface and the oxygen of the borate. On the contrary, the molten B2O3 remains intact with no chemical reactions which accounts for its poor adhesion on the Fe2O3 surface. Furthermore, the Blue Moon method was applied to predict bond dissociation and charge analysis was used to rationalize the differences in binding mechanisms at the lubricant-steel interfaces. The above simulations provide a theoretical interpretation for the lubricity of sodium borate and boron oxide at elevated temperature.

The inhibitory effects of four inhibitors on the solution adsorption of CaCO3 on Fe3O4 and Fe2O3 surfaces

This study presents the inhibitory effects of four scale inhibitors, including polyacrylic acid (PAA), hydrolyzed polymaleic anhydride (HPMA), polyepoxysuccinic acid (PESA) and polyaspartic acid (PASP), on the adsorption of CaCO3 on the surfaces of Fe3O4 and Fe2O3. Samples were characterized using SEM and EDS and the average atomic number ratios of Ca/Fe were calculated. Inhibition effects followed the trend: PESA > PAA > PASP > HPMA and PESA > PASP > HPMA > PAA for Fe3O4 and Fe2O3, respectively. Molecular dynamics simulations based on the adsorption model of the scale inhibitor on the surface and calculations of the adsorption energy between the scale inhibitor molecule and the surface revealed that the relatively high scale inhibitory effect is due to low adsorption energy between the inhibitor molecule and the surface. Density Functional Theory (DFT) calculations of the model after adsorption revealed that the relatively low adsorption energy depends on the number of H-O bonds formed as well as those with higher Mulliken population values between the scale inhibitor and the surface.

Triclosan removal by heterogeneous Fenton-like process: Studying the kinetics and surface chemistry of Fe3O4 as catalyst

Fe3O4 was used as a recoverable catalyst in heterogeneous Fenton-like process for Triclosan (TCS) degradation in this study. The kinetics and surface chemistry of the catalyst were investigated in detail. Peroxymonosulfate (PMS) was used to generate radicals and found to be an effective oxidant used with Fe3O4. The effects of Fe3O4 and PMS dosage, adsorption, pH and catalyst surface charges were studied. The system is at optimum at [TCS:PMS] at 1:25 and increases linearly with Fe3O4 dosage from 0.125 to 0.750 g/L. Under the optimum condition, TCS was removed in less than 60 min. It is concluded that Fe3O4 has the role of both adsorbent and catalyst. TCS and PMS are adsorbed near or onto Fe3O4 surface for catalytic reactions. The pH level has a critical effect on the reaction as it changes the form of active sites of Fe3O4. The active site of Fe3O4 is positive ( Fe−OH2+) in acidic and negative ( Fe–O−) in alkaline solution, leading to different adsorbility of PMS and TCS. The optimum pH for this reaction is in pH 6–9, in which the low surface charges on Fe3O4 allow both PMS and TCS to access active sites and form inner-sphere complex for reaction.

Agglomeration Mechanism of Complex Ti-Al Oxides in Liquid Ferrous Alloys Considering High-Temperature Interfacial Phenomenon

This work presents the agglomeration mechanism of complex Ti-Al oxides in the liquid ferrous alloy. Cluster characteristics were investigated using Al and Ti/Al-complex deoxidation method in lab scale. The time-dependent size distribution, total number per volume, average size, and circularity of the clusters were quantitatively analyzed. Furthermore, high-temperature confocal laser scanning microscopy was utilized to directly observe the cluster formation of Ti-Al oxides. A capillary force model including wettability parameters was applied to compare the agglomeration capabilities of different types of non-metallic inclusions. When a low Ti is added into melt, the agglomeration of TiOx·FeO liquid inclusions is one of the key factors to decrease the frequency of cluster formation. When the Al is added into melt, the heterogeneous precipitation on TiOx·FeO surfaces is the main reaction process. Ti-Al oxides have lower agglomeration ability than that of Al2O3, which in turn, contribute to a low agglomeration frequency as well.

Magnetic solid-phase extraction of sulfonamide antibiotics in water and animal-derived food samples using core-shell magnetite and molybdenum disulfide nanocomposite adsorbent

A molybdenum disulfide(MoS2)-based core-shell magnetic nanocomposite (Fe3O4@MoS2) was synthesized by the stepwise hydrothermal method. Two-dimension ultrathin MoS2 sheets with a thickness of approximately 20 nm were grown in situ on the surface of Fe3O4 (∼200 nm). They were employed as an adsorbent for the magnetic solid-phase extraction (MSPE) of sulfonamide antibiotics (SAs) from water samples. High-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was used for SA quantitation. Extraction parameters, including the pH effect, amount of Fe3O4@MoS2, extraction time, temperature, and desorption conditions, were systematically investigated. The electrostatic interaction between the positively charged SAs and negatively charged MoS2 nanoparticles in the optimal extraction conditions enhanced the adsorption of SAs on the sorbent surface. Under chosen conditions, the proposed strategy achieved wide linear range of 1.0–1000 ng·L−1 SAs, low limits of detection (LOD, 0.20–1.15 ng·L−1, S/N = 3:1), good trueness (recoveries between 85.50–111.5%), satisfactory repeatability and reproducibility (relative standard deviation, <10%, n = 5), and excellent recoveries between 80.20% and 108.6% for SAs determination in spiked waste water samples. The proposed strategy was validated and successfully applied for the analysis of water, milk, pork meat and fish meat. The nanocomposites, which have the combined advantages of magnetic separation and high adsorption affinity toward SAs, are a promising sorbent for antibiotics extraction from real samples.

Curing epoxy with polyethylene glycol (PEG) surface-functionalized GdxFe3-xO4 magnetic nanoparticles

Lanthanide-doped Fe3O4 nanoparticles were synthesized and functionalized via electrodeposition method using which gadolinium cations (Gd3+) were exchanged partially with Fe3+ in the ferrite lattice. Polyethylene glycol (PEG) was grafted onto the surface of Fe3O4 and Gd-doped Fe3O4 to study its potential for epoxy curing. X-Ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometry (VSM) confirmed successful synthesis, and bulk- and surface modification of Fe3O4 and Gd-Fe3O4 and PEG-Gd-Fe3O4. Nonisothermal differential scanning calorimetry (DSC) on samples containing 0.1 wt.% of nanoparticles was indicative of Poor cure for epoxy/Fe3O4 and epoxy/Gd-Fe3O4, while Excellent cure for epoxy/PEG-Gd-Fe3O4, demonstrating promising role of Gd in epoxy ring opening.

Preparation of magnetic polyethylenimine lignin and its adsorption of Pb(II)

In this paper, magnetic polyethyleneimine lignin (M-Lignin-PEI) was prepared by a reversed-phase suspension crosslinking method to remove Pb (II) form aqueous solutions. SEM, FT-IR, TGA, XRD and VSM technology were employed to explain their structures. Batch adsorption experiments for Pb (II) were carried out to estimate their adsorption performance. Results showed that lignin successfully grafted with polyethyleneimine and coated on the surface of Fe3O4 with a saturation magnetization of 24.08 emu/g, which could achieve good solid-liquid separation. In addition, the experiment results indicated that the adsorption of Pb (II) by M-Lignin-PEI was in line with Langmuir model, and the adsorption process could be described by a pseudo-second-order model, suggesting that Pb (II) adsorption onto sorbents were a chemical process and monolayer adsorption. The maximum adsorption capacity of M-Lignin-PEI for Pb (II) could reach 96.60 mg/g and the removal rate was 99.73%. Moreover，the lead-loading M-Lignin-PEI could be easily regenerated with only 15% decrease of adsorption capacity after five times regeneration.

Enhanced Selective Production of Carbonyl Products for Aerobic Oxidation of Benzylic Alcohols over Mesoporous Fe2O3 Supported Gold Nanoparticles

Ordered mesoporous Fe2O3 supported gold nanoparticles with a desired specific surface area and porous structure (Au/meso-Fe2O3) was successfully fabricated with a hard templating method by using KIT-6 as the template. The morphology and physico-chemical properties of Au/meso-Fe2O3 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), etc. The gold nanoparticles are highly dispersed on the surface of the mesoporous Fe2O3. The catalytic performance of the synthesized catalyst was studied for the aerobic oxidation of benzylic alcohols in β–O–4 linked lignin model dimers to the corresponding carbonyl products under atmosphere pressure. Au/meso-Fe2O3 shows an enhanced activity for the aerobic oxidation of 1-phenylethanol in comparison with that of Au/bulk-Fe2O3. The promoted catalytic activity is related to the confined porous structure of mesoporous Fe2O3 and more boundaries contact between gold and meso-Fe2O3, which shows that the porous structure of the support has a significant influence on the activity of gold catalysts.

Removal of Arsenic(III) from water using magnetite precipitated onto Douglas fir biochar

Magnetic Fe3O4/Douglas fir biochar composites (MBC) were prepared with a 29.2% wt. Fe3O4 loading and used to treat As(III)-contaminated water. Toxicity of As(III) (inorganic) is significantly greater than As(V) and more difficult to remove from water. Removal efficiency was optimized verses pH, contact time and initial concentration. Column sorption and regeneration were also studied. Adsorption kinetics data best fitted the pseudo second order model (R2 > 0.99). Adsorption was analyzed with three isotherm models at 20, 25 and 40 °C. The Sips isotherm showed the best fit at 25 °C with a 5.49 mg/g adsorption capacity, which is comparable with other adsorbents. MBC gave faster kinetics (~1–1.5 h) at pH 7 and ambient temperature than previous adsorbents. The Gibbs free energy (ΔG) of this spontaneous As(III) adsorption was −35 kJ/mol and ΔH = 70 kJ/mol was endothermic. Experiments were performed on industrial and laboratory wastewater samples in the presence of other co-existing contaminants (pharmaceutical residues, heavy metals ions and oxi-anions). The composite reduced the arsenic concentrations below the WHO's safe limit of 0.2 mg/L for waste water discharge. X-ray photoelectron spectroscopy (XPS) studies found As(III) and less toxic As(V) on Fe3O4 surfaces indicating adsorbed (or adsorbing) As(III) oxidation occurred upon contact with O2 and possibly dissolved Fe(III) or upon drying under oxic conditions. Under anoxic conditions magnetite to maghemite transformation drives the oxidation. A pH-dependent surface chemisorption mechanism was proposed governing adsorption aided by XPS studies vs pH.

Ag‐deposited carbon‐coated Fe 3 O 4 magnetic microparticles as highly efficient and recyclable catalysts

In this work, Ag nanoparticles (AgNPs) with average sizes of 20 nm were well-dispersed on the surfaces of magnetic carbon-coated Fe3O4 (Fe3O4@C) microparticles through a simple in situ growth process. The catalytic efficiency of the as-prepared AgNPs-decorated Fe3O4@C particles was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NP) by an excess of NaBH4. The kinetic data of the reduction reaction could be explained by the assumption of a pseudo-first-order reaction with regard to 4-NP. Also the particles are catalytically more active due to their extremely high-density AgNPs immobilised on the surfaces of Fe3O4@C particles. Significantly, the Fe3O4@C@Ag catalysts can be easily separated from the reaction media by applying an external magnet, and can be reused for several cycles.

DFT Analysis of Amino Acid Functionalization of Hematite for Electroreduction Catalysis

In a future with plentiful renewable electricity, electro-chemical systems to carry out chemical transformations can provide an efficient and sustainable alternative to fossil-fuel based energy consumption. Several important chemical reactions, such as CO2 and N2 reduction, have electro-chemical counterparts to form useful products through a series of proton-coupled electron transfer (PCET) reactions. The activity and selectivity of PCET reactions can significantly be impacted by the electrode-electrolyte interfacial properties, and tuning this near-surface environment can be used as a control towards developing active and selective electrochemical conversions. Surface-bound amino acid chains can be used to alter the electrocatalytic performance by altering the active site structure and local environment. We used Density Functional Theory (DFT) to study the surface binding of short amino acid chains on Fe2O3 surfaces to understand how they alter the interfacial environment through surface-ligand interactions. We examine the effects of small amino acid binding on the stability of different Fe2O3 terminations in the electrochemical environment. We consider how presence of continuum solvation affects the binding preferences of the amino acid. Coverage effects on binding energies are also evaluated. We then examine how these amino acid or peptide chain can act as shuttling agents to alter the energetics and kinetic barriers of PCET reactions.

Simulation of the relationship between calcium carbonate fouling and corrosion of iron surface

The heat resistance will increase dramatically with the adhesion of fouling, resulting in the decrease of heat exchange efficiency. To study the relationship between calcium carbonate fouling and corrosion of iron surface, the most stable adsorption site of Ca2+, charge transfer process during adsorption and electronic density of states were analyzed. Additionally, the adsorption of fouling ions on Fe(111) and Fe2O3(001) surface were simulated with methods of first-principles and molecular dynamics, respectively. Results reveal that the most stable adsorption position of Ca2+ on Fe(111) surface is at triple hole site. Ca2+ will get charge from the top Fe atoms and then the Fe atoms become more active and susceptible to be electrochemically corroded. Diffusivity of Ca2+ in CaCO3 aqueous solution on Fe2O3(001) surface is larger than those on Fe(111) surface, which manifests that the fouling ions are prone to adhere to the corroded surface and the process of fouling deposition is accelerated at the same time. The work provides evidence that fouling ions in the aqueous solution are closely related to the corrosion. Thus, the combined role of corrosion resistance and anti-fouling performance should be taken into consideration during the surface optimization.

Three-dimensionally ordered macroporous Fe-doped ceria catalyst with enhanced activity at a wide operating temperature window for selective catalytic reduction of NOx

A series of three-dimensional ordered macroporous (3DOM) Ce-Fe composite oxides are synthesized for selective catalytic reduction of NOx by CO. The optimized 3DOM Ce0.6Fe0.4O2 catalyst has nearly 90% NO conversion at a relatively low temperature (200 °C) and high catalytic activity in a wide operating temperature window of 200–700 °C. Adding appropriate amount of Fe into pure cerium can form Ce-Fe solid solution, which can promote the reduction performance and further improve oxygen vacancies and active oxygen species. Meanwhile, the introduction of Fe further improves the specific surface area and pore volume of the 3DOM structure, which provides more active sites and improves the more effective contact between the reaction gas and the catalyst. Moreover, surface Fe2O3 can be used as a storage site for nitrite and nitrate and promote the adsorption of NOx species, which can be further desorbed/converted/dissociated. It can be seen that the reduction of NO by CO follows the Eley-Rideal (E-R) mechanism, which can be proved by in situ DRIFTS. There is no doubt that the coexistence of Ce-Fe solid solution and Fe2O3 in 3DOM Ce0.6Fe0.4O2 catalyst is the key reason for the excellent catalytic activity of NO + CO reaction.

One-step fabrication of bifunctional self-assembled oligopeptides anchored magnetic carbon nanoparticles and their application in copper (II) ions removal from aqueous solutions

Copper ion (Cu (II)) pollution has attracted much attention due to its remarkable toxic domino effect at excess amount. Efficient Cu (II) ions removal is thus a prerequisite for wastewater recycling. Herein, we present a facile and environmentally benign strategy to fabricate thiol (SH)-functionalized Fe3O4@C nanoparticles (denoted as Fe3O4@C-SH NPs) based on one-step self-assembling of a bifunctional oligopeptide with a sequence of Cys-Lys-Cys-Lys-Cys-Lys (CK–VI) for highly efficient removal of copper ions (Cu (II)) in aqueous solutions. Under the physiological conditions, CK–VI readily self-organized into a robust and tailor-made functional monolayer predominately composed of well-packed β-sheets on the surface of Fe3O4@C NPs with their thiol groups standing on the outermost layer. The resulting Fe3O4@C-SH NPs containing abundant thiol active sites exhibited excellent adsorption capacity (up to 28.8 mg g−1) and selectivity for Cu (II) ions over coexisting ions. Compared with other covalent grafting methods with multistep processes and in harsh conditions, the proposed oligopeptides assembly-based coating method makes it possible to rapidly fabricate the Fe3O4@C-SH NPs in a simple mild one-step aqueous process with low cost. The current study provides facile and environmentally friendly approaches to rapidly tailor multifunctional surfaces of NPs for various toxic metal ions removal from wastewater.

Facile fabrication of Au/Fe3O4 nanocomposites as excellent nanocatalyst for ultrafast recyclable reduction of 4-nitropheol

A highly efficient Au/Fe3O4 nanocatalyst is fabricated by using a seed deposition method, and is characterized by XRD, TEM, EDS, XPS, UV–vis and VSM, respectively. TEM image shows that small Au nanoparticles are immobilized onto Fe3O4 surface uniformly and densely. After immersion treatment by NaBH4, the Au/Fe3O4 nanocatalyst exhibits high catalytic efficiency in reducing 4-nitrophenol to 4-aminophenol. The 4-nitrophenol could be fully degraded in less than one minute. The Au/Fe3O4 nanocatalyst demonstrate good magnetic recoverability and high conversion in 1 min (>98%) after 8 successive cycles. The reaction rate constant k of the catalyst with volume Au sol/mass Fe3O4 microspheres ratio 3 (Au/FeO-3) is 13.8 min−1, which is 4.7 times larger than that of Au/FeO-1. The catalytic mechanisms were discussed. This work provides a simple and environmentally friendly method for preparing magnetic noble nanocatalyst used for 4-nitrophenol reduction.

Targeted Heating of Enzyme Systems Based on Photothermal Materials.

This study demonstrates that the enzymatic reaction rate can be increased significantly by targeted heating of the microenvironment around the enzyme, while maintaining the reaction system at environmental temperature. Enzyme molecules are covalently attached to the surface of Fe3 O4 @reduced graphite oxide (rGO). Under visible-light irradiation, the reaction rate catalyzed by the enzyme-Fe3 O4 @rGO system is clearly enhanced relative to that of the free enzyme and a mixture of free enzyme and Fe3 O4 @rGO. This local heating mechanism contributes to promotion of the enzymatic reactions of the targeted heating of the enzyme (THE) system, which has been validated by using different enzymes, including lipase, glucose oxidase, and organophosphorus hydrolase. These results indicate that targeted heating of the catalytic centers has the same effect on speeding up reactions as that of traditional heating methods, which treat the whole reaction system. As an example, it is shown that the THE system promotes the sensitivity of an enzyme screen-printed electrode by 14 times at room temperature, which implies that the THE system can be advantageous in improving enzyme efficiency, especially if heating the entire system is impossible or could lead to degradation of substrates or damage of components, such as in vitro bioanalysis of frangible molecules or in vivo diagnosis.

Nano‐engineering of high‐performance PA6.6 nanocomposites by the integration of CVD‐grown carbon fiber on graphene as a bicomponent reinforcement by melt‐compounding

ABSTRACTIn this study, long carbon nanofibers (CNFs) were grown on graphene nanoplatelets (GNPs) by chemical vapor deposition (CVD) technique to develop three‐dimensional (3D) bicomponent nanostructures. The structure and properties of graphene before and after CVD process were investigated in details. X‐ray photoelectron analysis depicted the formation of Fe‐C bonds by the deposition of carbon atoms on the catalyst surface of Fe2O3. This hybrid additive was firstly used as a reinforcing agent in melt compounding to fabricate PA6.6‐based nanocomposites with enhanced mechanical and thermal properties. Both GNP and CNF‐GNP have enough surface oxygen functional groups to improve the interfacial interactions with polyamide matrix and thus provide good wettability. Also, both neat GNP and its bicomponent additive with CNF also acted as a nucleating agent and allowed the crystal growth in nanocomposite structure. Homogeneous dispersion of nanoparticles was achieved by using thermokinetic mixer during compounding by applying high shear rates. Mechanical results showed that 23 and 34% improvement in flexural and tensile modulus values, respectively, was attained by the addition of 0.5 wt % CNF‐GNP hybrid additive. The heat distortion temperature and Vicat softening temperature of the resulting PA6.6 nanocomposites were improved compared to neat PA6.6 material indicating performance enhancement at higher service temperature conditions. CNF was successfully grown on Fe‐loaded GNP by CVD method and this hybrid additive was compounded with PA6.6 by melt‐mixing process. Mechanical results showed that 34% improvement in tensile modulus value was attained by the addition of 0.5 wt % CNF‐GNP hybrid additive because it acted as a nucleating agent and allowed the crystal growth in the nanocomposite structure. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48347.