Peak Splitting Research Articles

Square-wave voltammetric evaluation of electrochemical constants: Comparative study with other techniques

Square-wave voltammetry was employed for evaluation of electrochemical rate constants for soluble hexacyanoferrate ions as well as for iron hexacyanoferrate (Prussian blue) and nickel hexacyanoferrate immobilized on carbon electrodes. Modelling of square-wave response of immobilized species with assumption of Nernstian behavior, the dimensionless net current peak splitting occurs. The peak value decreases with the rise of square-wave amplitude Esw and splits around the common value of 50 mV. For a quasireversible behavior, the dimensionless net peak current has an extremum depending on both frequency and Esw. At 40 mV, the frequency in the extremum almost coincides with the surface electrochemical rate constant ksur. For practical confirmation, the Prussian blue film was studied at different frequencies (Esw = 50 mV). At lower values, the reaction is relatively fast and net peak current splitting occurs. At higher values, the net response reaches its maximum allowing to evaluate the surface electrochemical rate constant. A comparative investigations of electrode kinetics (for both surface and heterogeneous electrochemical constant) by different electrochemical methods proved the advantages of square-wave pulse technique. In contrast to cyclic voltammetry and electrochemical impedance spectroscopy, the square-wave voltammetry has lower variation of estimated parameters, relatively simple calculations, uncomplicated simulation of different mechanisms.

Synthesis of Copper-Substituted Polyoxovanadate and Oxidation of 1-Phenyl Ethanol

Dicopper-substituted polyoxovanadate [Cu2V16O44(NO3)]5− (Cu2V16) was synthesized through the reaction of [Cu2V8O24]4− and [V4O12]4− in the presence of nitrate salt. From single crystal X-ray analysis, Cu2V16 exhibited the same helical structure as that of nitrate-incorporated polyoxovanadate, [V18O46(NO3)]5− (V18). Both complexes had the same framework with the same guest anion and are considered to be substituted isomers for each other by replacing two Cu2+ ions and two [VO]2+ ions. The incorporated nitrate showed short and long N–O bond lengths (1.14, 1.26 and 1.30 Å) as in the case of V18 (1.09, 1.16 and 1.28 Å). Reflecting the inequivalent bond lengths of the nitrate, the IR spectrum of V18 shows split peaks at 1359 and 1342 cm−1. But the Cu2V16 spectrum showed a single peak due to the presence of nitrate at 1353 cm−1. When the temperature was lowered, the nitrate peak in Cu2V16 was split into two positions at 1354 and 1345 cm−1 when the temperature reached −140 °C. These results indicate that the nitrate incorporated in Cu2V16 rotates relatively easily in the Cu2V16 cavity at room temperature compared to V18. In addition, the oxidation of 1-phenyl ethanol to acetophenone with Cu2V16 smoothly proceeded in comparison with V18. By taking advantage of the same framework in both catalysts, we can deduce the position of potential active sites in the oxidation reaction. We have concluded that the most active site is not on the peripheral of the vanadate framework, but it is reasonable to suggest that the active site is on the substituted copper atoms rather than the polyoxovanadate framework.

Gemological and Spectral Characteristics of Gem-Quality Blue Gahnite from Nigeria

Gem-quality blue octahedral crystalline gahnite was produced in Nigeria. This paper investigated gemological and spectroscopic characteristics by basic gemological experiments, electron probes, infrared reflectance spectroscopy, laser Raman spectroscopy, photoluminescence spectroscopy, and ultraviolet-visible spectroscopy. The results show that the refractive index (RI) of Nigerian gahnite is 1.792∼1.794, and the specific gravity is 4.45∼4.66, with no fluorescence. The main chemical composition is ZnAl2O4, accounting for 93.57%, and the rest is mainly FeAl2O4, which also contains Na, Mg, Co, Mn, Cr, Cu, Si, K, and Ca elements. The infrared spectra showed midinfrared absorption bands near 510 cm−1, 559 cm−1, and 664 cm−1 in the fingerprint region, corresponding to the Zn-O stretching vibration, bending vibration, and Al-O bending vibration, respectively. The Raman spectra showed three of the five Raman active modes of the spinel group, with characteristic Raman absorption peaks located at 418 cm−1, 508 cm−1, and 660 cm−1, corresponding to Eg, T2g(2), and T2g(3) modes, respectively, and the comparison revealed a higher degree of Zn and Al ordering in this paper for gahnite. The photoluminescence spectra show the common Cr3+-activated fluorescence splitting peaks of natural spinel, of which the 686 nm (R-line) fluorescence peak is obvious and sharp. The UV-vis absorption spectra located at 444 nm and 489 nm are the most obvious, which are caused by the d-d electron leap of TFe2+ (5E ⟶ 5T2), and the blue-gray tones of the samples are mainly caused by the spin-forbidden electronic transitions in TFe2+ and MFe2+ ↔ MFe3+; the weak absorption peak at 609 nm was determined to be associated with Co2+ by derivative spectra.

Study of Bragg scattering in the presence of dipole-dipole interaction in plasmonic nanohybrids

We have developed a theory of the Bragg scattering for metallic nanohybrid made of an ensemble of metallic nanorods doped in a substrate. The substrate can gas, liquid or solid. An external laser field is applied to study the Bragg scattered light. The photons from the incident laser interact with the surface plasmons od nanorods and produce surface plasmon polaritons (SPPs). The incident laser field also induced dipoles in the ensemble of nanorods and they interact with each other via the dipole-dipole interaction (DDI). We have developed a theory for Bragg scattering for metallic nanohybrids using the coupled-mode formulism based on Maxwell’s equation in the presence of SPP and DDI fields. It is found that the theory of Bragg scattered depends on the susceptibility induced by the SPP and DDI fields. We used the quantum mechanical density matrix method to calculate the susceptibility. An analytical expression of the Bragg scattered light intensity is obtained. These expressions can be useful for experimental scientists and engineers who can used them to compare their experiments and make new types of plasmonic devices. Next, we have compared our theory with the experiment data for a nanohybrid made of ensemble of Au-nanoris doped in water. We found a good agreement between theory and experiments. We have also performed the numerical simulations to study the effect of SPP and DDI fields on the Bragg intensity. We have predicted an enhancement the Brag intensity due to the SPP and DDI couplings. The enhancement is due to the two extra scattering mechanisms of the SPP and DDI polaritons with acoustic phonons. We have also found that the one peak in the Bragg intensity can be split int many peaks due the SPP coupling, DDI coupling and phase factor. The splitting is due the Bragg factor appearing in the theory, and it includes the coupling of the incident laser, SPP and DDI electric fields with of acoustic phonons. The enhancement effect can be used to fabricate new types of nanosensors. Similarity, splitting phenomenon can be used to fabricate new types nanoswitches where one peak can be considered as the OFF position and many peaks can be considered as the ON position.

Uncommon causes of hemoglobin E flags identified during measurement of hemoglobin A1c by ion-exchange high-performance liquid chromatography.

We present 3 cases of discordant results from screening hemoglobin A1c (HbA1c) measured by ion-exchange high-performance liquid chromatography (HPLC) all due to various forms of interference and flagged by the instrument as "suspected hemoglobin E (HbE)." The first case was due to a rare hemoglobin variant, later confirmed to be hemoglobin Hoshida, the second due to "true" heterozygous HbE, and the third a result of analytical artifact causing splitting of the HbA1c peak without an underlying variant hemoglobin. We examine the similarities in these cases along with the laboratory work-up to classify each cause of interference to demonstrate the wide array of potential causes for the suspected HbE flag and why it warrants proper work-up. Because there is no standardized method of reporting out hemoglobin variant interference in HbA1c measurement, we discuss our laboratory's process of investigating discordant HbA1c measurements and reporting results in cases with variant interference as 1 possible model to follow, along with discussing the associated laboratory, ethical, and clinical considerations. We also examine the structure of hemoglobin Hoshida, HbE, and conduct a brief literature review of previous reports.

Experimental characterization of defect-induced Raman spectroscopy in graphene with BN, ZnO, Al2O3, and TiO2 dopants

The introduction of boron nitride (BN), zinc oxide (ZnO), aluminum oxide (Al2O3), and titanium oxide (TiO2) as dopants in pristine graphene leads to the modification of its transport properties, resulting in the production of graphene semiconductors and alteration of its semiconductive characteristics. The achievement of high-quality electronic devices necessitates considering doping and producing a broader energy bandgap in graphene. The optical determination of charge density in intrinsic graphene may be achieved by utilizing the D Raman peak, where an increased charge density is associated with a decreasing peak split. Strong connections have been seen between the energy bandgap (Eg) and the locations of the G and D peaks. Various doping materials exhibit distinct variations and effects on the doping process of graphene. The determination of doping levels in graphene may be achieved with far greater accuracy by observing the ID/IG ratios, compared to the traditional method of measuring the G-band shift with charge. The determination of average crystallite size, as well as the observation of the parameter La, is crucial in comprehending the doping and flaws present in graphene materials that have been manufactured.

A and B site engineered doping of the Bi2O3 to tune the structural and optical properties of lead-free BCZT ceramic

This work reports the different solid-state synthesis routes to tune between the A-site and B-site incorporation of the Bi2O3 additive element in the lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramic. The structural and optical properties of the synthesized samples were systematically investigated by utilizing XRD, FT-IR spectroscopy, Raman Spectroscopy, UV–visible, and Photoluminescence spectroscopy. The shifting of the XRD peaks towards higher angles and the decrement of the O–Ba–O bond length in the FT-IR spectra of the doped sample confirmed the A-site incorporation of the Bi3+ ion. Whereas, B-site substituted samples have shown the lower angle shifting of the XRD peaks and increased value of the O–Ti–O bond length in FT-IR spectra. The presence of co-existing multi-phases in all prepared ceramics structures were verified by the splitting of XRD peaks and Raman Spectroscopy data analysis. A significant decrement in the value of the energy band gap and higher emission intensity for the A-site doped sample was observed from the UV–visible and PL spectra respectively. These observations made from the optical properties indicate that the A-site substituted ceramics can greatly enhance the electrical and optical properties of the pure material concerning the B-site substituted ceramics.

Beyond the Condon limit: Condensed phase optical spectra from atomistic simulations.

While dark transitions made bright by molecular motions determine the optoelectronic properties of many materials, simulating such non-Condon effects in condensed phase spectroscopy remains a fundamental challenge. We derive a Gaussian theory to predict and analyze condensed phase optical spectra beyond the Condon limit. Our theory introduces novel quantities that encode how nuclear motions modulate the energy gap and transition dipole of electronic transitions in the form of spectral densities. By formulating the theory through a statistical framework of thermal averages and fluctuations, we circumvent the limitations of widely used microscopically harmonic theories, allowing us to tackle systems with generally anharmonic atomistic interactions and non-Condon fluctuations of arbitrary strength. We show how to calculate these spectral densities using first-principles simulations, capturing realistic molecular interactions and incorporating finite-temperature, disorder, and dynamical effects. Our theory accurately predicts the spectra of systems known to exhibit strong non-Condon effects (phenolate in various solvents) and reveals distinct mechanisms for electronic peak splitting: timescale separation of modes that tune non-Condon effects and spectral interference from correlated energy gap and transition dipole fluctuations. We further introduce analysis tools to identify how intramolecular vibrations, solute-solvent interactions, and environmental polarization effects impact dark transitions. Moreover, we prove an upper bound on the strength of cross correlated energy gap and transition dipole fluctuations, thereby elucidating a simple condition that a system must follow for our theory to accurately predict its spectrum.

The net peak splitting phenomenon in square-wave voltammetry – A simple diagnostic tool to distinguish between surface electrode mechanisms associated with different chemical reactions

Utilizing pulse voltammetric techniques for the electrochemical analysis of lipophilic redox systems has proven to be an effective method for studying a diverse range of redox compounds, from simple molecules to intricate proteins. To extract relevant thermodynamic and kinetic data from electrochemical analysis of redox systems exhibiting strong surface activity, there's a crucial need to decipher the underlying electrochemical mechanism in the system being examined. The "split net peak" phenomenon, a defining characteristic observed in all surface-active redox systems featuring fast electron transfer under square-wave voltammetry conditions, has been investigated in this study to establish diagnostic criteria for identifying surface electrochemical mechanisms associated with preceding, subsequent, regenerative, and reactant-inactivating chemical reactions. This understanding can be achieved by tracking the influence of the chemical reaction rate on the split square-wave voltammetric peaks in a particular electrochemical mechanism. The approach reported in the current work enables a very simple and precise differentiation between the elaborated mechanisms frequently encountered in protein-film voltammetry methodologies.

Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting

AbstractIn order to understand the mechanical properties and the fracture surface roughness characteristics of thermally damaged granite under dynamic splitting, dynamic Brazilian splitting tests were conducted on granite samples after thermal treatment at 25, 200, 400, and 600°C. Results show that the dynamic peak splitting strength of thermally damaged granite samples increases with increasing strain rate, showing obvious strain‐rate sensitivity. With increasing temperature, thermally induced cracks in granite transform from intergranular cracks to intragranular cracks, and to a transgranular crack network. Thermally induced damages reduce the dynamic peak splitting strength and the maximum absorbed energy while increasing the peak radial strain. The fracture mode of the thermally damaged granite under dynamic loads is mode II splitting failure. By using the axial roughness index , the distribution ranges of the wedge‐shaped failure zones and the tensile failure zones in the fracture surfaces under dynamic Brazilian splitting can be effectively identified. The radial roughness index is sensitive to the strain rate and temperature. It shows a linear correlation with the peak splitting strength and the maximum absorbed energy and a linear negative correlation with the peak radial strain. can be used to quantitatively estimate the dynamic parameters based on the models proposed.

An NMR-based approach for the design of crystallization processes for rigid molecules and effects of molecular rigidity and impurities on crystallization pathways

A methodology based on NMR analysis to enable development of crystallization procedures for relatively rigid molecules is presented. The number of relatively stable conformers in solution and their relative proportions are determined from peak splitting of equivalent protons and their relative areas as measured by NMR. Experimental data indicated that slow conformational interconversion was limiting crystallization at low temperatures. Variable temperature NMR analysis was utilized to determine rotamers’ peak coalescence and identify a suitable crystallization solvent. This NMR-based approach led to the development of a manufacturing crystallization recipe of a relatively rigid molecule that was impossible to crystallize via a scalable process. Furthermore, prediction of relatively stable conformer in gas phase, determined by Molecular Dynamics (MD) calculations were in acceptable agreement with data obtained from NMR analyses. Finally, the effects of molecular rigidity and impurities on crystallization and oiling-out pathways are described and an approach to avoid oiling-out is presented.

Mapping spin interactions from conductance peak splitting in Coulomb blockade

Mapping spin interactions from conductance peak splitting in Coulomb blockade

Effect of injecting inert gas at different spontaneous combustion stages on active groups in coal

Inert gas injection into the mine gob where coal spontaneous combustion occurs can effectively avoid the loss of coal resources, reduce greenhouse gas emissions and realize the green and sustainable mining of coal resources. In this paper, a continuous process of abruptly changing coal from an oxygenated atmosphere to an inert atmosphere in one experiment was realized by a gas atmosphere conversion device, and the effect of inert gas injection on reactive groups in coal at different stages of oxidation was studied based on electron spin resonance technique and spectral peak splitting fitting technique. The experimental results show that the g factor of lignite decreases slowly and then increases with the rising temperature under dry air, and the g factor turning point temperature is 80 °C. The concentration of radicals in lignite increases continuously with rising temperature. The injection of N2 and CO2 at 130 °C has the most significant inhibitory effect on the g factor of coal, with 41.61 % and 65.11 %, respectively. After injecting N2 and CO2 at different stages, the radical concentration of coal suddenly decreases and then continues to increase with the extension of constant temperature time, and the injection of N2 and CO2 at 130 °C has the most significant inhibitory effect on the radical concentration of coal, 28.35 % and 35.44 %, respectively. The radicals in coal can be classified into oxygen-containing radicals, aliphatic radicals, simple aromatic radicals, and π- or σ-type oxygen-containing radicals by the spectroscopic peak splitting technique. The injection of inert gas produces a significant inhibition effect on oxygen-containing radicals in coal. And finally, the inhibition pathway of inert gas on oxygen-containing radicals in coal was revealed from the perspective of radical reaction.

Study on dynamic splitting tensile mechanical properties and microscopic mechanism analysis of steel fiber reinforced concrete

With high compressive strength and high fracture toughness, steel fiber reinforced concrete is widely used in large-span bridges and high-rise buildings. Since concrete structures are subjected to strong dynamic loads such as impact blast during service, it is essential to clarify the dynamic mechanical behavior of steel fiber reinforced concrete and to propose an adapted dynamic constitutive model for structural dynamic response calculation. Therefore, in this paper, a static and dynamic splitting tensile test study was conducted on steel fiber reinforced concrete with four fiber contents (0%, 1%, 2%, and 3%), and a separated Hopkinson compression bar (SHPB) was used to conduct dynamic splitting tensile tests on steel fiber reinforced concrete to obtain the failure pattern, stress–strain curves, and basic mechanical parameters of steel fiber reinforced concrete. The results showed that the static and dynamic splitting tensile strength of steel fiber reinforced concrete increased with increased steel fiber content. The dynamic splitting tensile strength and peak deformation of steel fiber reinforced concrete increased significantly with increasing strain rate, and the dynamic splitting tensile strength of steel fiber reinforced concrete increased in the range of 1.1 to 3.3 compared with static splitting tensile strength. The enhancement of dynamic splitting tensile strength with increasing strain rate at different fiber contents showed a significant and then flattening trend. In addition, the dynamic splitting tensile strength and strain-rate sensitivity of non-steel fibered concrete are higher than that of steel fiber reinforced concrete. Meanwhile, the X-CT scanning technique was applied to reveal the strain rate reinforcement and steel fiber reinforcement mechanism from the microscopic perspective. Finally, the K&C model was modified based on the experimental results and applied to the dynamic splitting tensile simulation of SHPB to verify the accuracy and adaptability of the proposed constitutive model. The research results finally provide a theoretical basis for the mechanical response of steel fiber reinforced concrete structures under impact blast.

LC-MS Approach to Decipher a Light Chain Chromatographic Peak Splitting of a Monoclonal Antibody.

Monoclonal antibodies (mAbs), like other protein therapeutics, are prone to various forms of degradation, some of which are difficult to distinguish from the native form yet may alter potency. A generalizable LC-MS approach was developed to enable quantitative analysis of isoAsp. In-depth understanding of product quality attributes (PQAs) enables optimization of the manufacturing process, better formulation selection, and decreases risk associated with product handling in the clinic or during shipment. Reversed-phase chromatographic peak splitting was observed when a mAb was exposed to elevated temperatures. Multiple LC-MS based methods were applied to identify the reason for peak splitting. The approach involved the use of complementary HPLC columns, multiple enzymatic digestions and different MS/MS ion dissociation methods. In addition, mAb potency was measured by enzyme-linked immunosorbent assay (ELISA). The split peaks had identical masses, and the root cause of the peak splitting was identified as isomerization of an aspartic acid located in the complementarity-determining region (CDR) of the light chain. And the early eluting and late eluting peaks were collected and performed enzymatic digestion to confirm the isoAsp enrichment in the early eluting peak. In addition, decreased potency was observed in the same heat-stressed sample, and the increased isoAsp levels in the CDR correlate well with a decrease of potency. Liquid chromatography-mass spectrometry (LC-MS) has been utilized extensively to assess PQAs of biological therapeutics. In this study, a generalizable LC-MS-based approach was developed to enable identification and quantitation of the isoAsp-containing peptides.

First-Principle Investigation of La0.7Ba0.3Mn(1-x)FexO3 Structural Properties Using CASTEP

<p>We conducted first-principles Density Functional Theory (DFT) calculations using the CASTEP software package to investigate the crystal structure and mechanical properties of Fe<sup>3+</sup>-doped La<sub>0.7</sub>Ba<sub>0.3</sub>MnO<sub>3</sub> material at the Mn<sup>3+</sup> site, with doping concentrations ranging up to 50%. Through geometry optimization, we simulated the X-ray diffraction (XRD) pattern. We observed that the doping of Fe did not result in a shift in the peak positions of the diffraction pattern. However, it led to an increase in intensity at the [012] peak and the splitting of peaks [104] and [110]. Regarding the mechanical properties, we examined the elastic constants and observed a reduction in the Bulk, Shear, and Young's modulus values. The Shear and Bulk modulus and Poisson's ratio indicated that La<sub>0.7</sub>Ba<sub>0.3</sub>Mn<sub>(1-x)</sub>Fe<sub>x</sub>O<sub>3</sub> becomes less ductile with increased Fe<sup>3+</sup> doping content. Furthermore, we performed calculations for the Debye temperature, which revealed a decrease in the thermal conductivity of the La<sub>0.7</sub>Ba<sub>0.3</sub>Mn<sub>(1-x)</sub>Fe<sub>x</sub>O<sub>3</sub> material.</p><p class="Abstract"> </p>

Exploring the structural and mechanical properties of single-Component Mo metallic glasses

In this paper, we employed molecular dynamics (MD) simulations to investigate how the cooling rate affects the structural and mechanical properties of molybdenum monoatomic glasses (Mo-MG). We also examined the influence of cooling rates on the glass transition temperature, showing a decrease as the cooling rates decreased. The analysis of structural properties using techniques such as radial distribution function (RDF), Voronoi tessellation analysis, and common neighbor analysis (CNA) revealed that the cooling rates have a significant impact on the local structure of Mo-MG. The RDF function displayed a splitting in the second peak, indicating the formation of a super-cooled liquid state. The CNA analysis identified the most dominant local structures as icosahedral configurations, specifically ⟨0,1,10,2⟩, ⟨0,0,12,0⟩, and ⟨0,0,12,2⟩. The mechanical properties were calculated using the Virial theorem implemented in the LAMMPS simulation software. The results indicated that the ultimate strengths of Mo-MG were comparable to those of crystalline molybdenum. However, the ultimate strength decreased with increasing cooling rate, indicating that higher cooling rates result in weaker Mo-MG samples. A similar trend was observed for Young's modulus, where increasing cooling rates led to a decrease in the stiffness of the formed Mo-MG.

Fractional order ATR-FTIR differential spectroscopy for detection of weak bands and assessing the radiation modifications in gamma sterilized UHMWPE.

This study presents a new method for identifying radiation modifications in UHMWPE polymer samples. The method involves using a mathematical technique called fractional order differential transformation on IR spectra obtained through ATR-FTIR spectroscopy. This new method was compared to existing techniques such as FTIR, XRD, and DSC, and it was found to be more sensitive and accurate in detecting radiation-induced changes in the polymer. The study focused on identifying changes in weak IR bands in the UHMWPE samples caused by gamma sterilization while simulating IR spectra using different orders of fractional derivatives and compared them to experimental spectra. It was found that applying a lower order of differentiation was more suitable for identifying radiation-induced changes in the UHMWPE samples. Using this method, they were able to identify specific changes in the gamma irradiated structure, such as the splitting of a single absorption peak into a doublet, which was only present in the 50 kGy irradiated sample. The study also used correlation index analysis, principal component analysis, and hierarchy cluster analysis to analyze the simulated and experimental spectra. These techniques allowed to confirm the effectiveness of the fractional order differential transformation method and to identify the specific regions of the IR spectra that were affected by radiation-induced changes in the UHMWPE samples. Overall, this study presents a new method for identifying radiation-induced changes in UHMWPE polymer samples that is more sensitive and accurate than existing techniques. By identifying these changes, researchers can better understand the effects of gamma sterilization on medical equipment and potentially develop new methods for sterilization that do not damage the equipment.

The acoustical behavior of a bass guitar bridge with no saddles.

The acoustics of a bass guitar bridge without saddles was tested experimentally and the results contextualised. Conclusions were obtained demonstrating that the bridge without saddles (where knot around the ball end of the string forms part of the sounding length) produced no measurable reduction in sustain and may increase the sustain for lower pitched strings, in comparison to a conventional bridge featuring saddles. The bridge without saddles showed a reduction in string inharmonicity, and produced a splitting of the frequency peaks associated within the resonances of the string. This peak splitting is explained as being due to differences in the frequency of vibrations parallel to and perpendicular to the body. Since the loop of core wire strongly resists vibration perpendicular to the body but vibrates freely as part of the sounding length for vibration parallel to the body, the relative length of the loop of core wire with respect to the sounding length of the string determines the fractional difference in frequency. The perceptual quality of the sound is similar to the beating due to multiple strings per note (as in piano) and to electronic chorus effects.

Evolution and prediction model of environmentally-persistent free radicals in biomass three-component pyrolytic carbon with pyrolysis temperature

To clarify the evolution mechanism of environmentally-persistent free radicals (EPFRs) in biochar as a function of pyrolysis temperature, three-component pyrolytic carbon was characterized by electron paramagnetic resonance (EPR) spectroscopy. Four types of EPFRs were distinguished by using the peak splitting method. The EPFRs in three-component pyrolytic carbon obtained at a pyrolysis temperature of 300 °C were mainly oxygen-containing free radicals (57.31–83.63 %). Upon increasing the pyrolysis temperature, simple aromatic ring radicals were formed by the dehydrogenation of biomass, and then the polymeric aromatic radicals formed, accompanied by π-electron delocalization to form phenyl-π radicals. Biomass pyrolysis was simulated by mechanically mixing the three components in different proportions. A comparison of the experimental and theoretical values indicated that interactions between the three components did not obviously affect the EPFR concentration in the range of 450–550 °C, with a maximum relative error of 12.78 %. A prediction model for the EPFRs concentration in multi-component pyrolytic carbon was proposed. This study also clarified the generation and transformation mechanisms of EPFRs in three-component pyrolytic carbon, thus providing guidance for generating and regulating biochar EPFRs.