Cyclic Sequence Research Articles

Research on Radial Vibration Model and Low-Frequency Vibration Suppression Method in PMSM by Injecting Multiple Symmetric Harmonic Currents

Driven by frequency conversion, the windings of a three-phase permanent magnet synchronous motor (PMSM) contain both odd and even harmonic currents. Due to the motor’s pole–slot conductance modulation, the interaction between the magnetic fields generated by these harmonic currents and the permanent magnet field results in harmonic radial vibrations of the motor. This paper analyzes the three-phase currents of the prototype and derives the radial magnetomotive force (MMF) spatiotemporal models for symmetric harmonic currents. By integrating Maxwell’s magnetic force formula and vibration response formula, the radial vibration models for symmetric harmonic currents are developed. The characteristics of vibrations caused by odd and even harmonic currents, as well as positive sequence and negative sequence harmonic currents, are analyzed separately. A cyclic sequence, low-frequency vibration suppression control method incorporating multiple harmonic current injections was designed. Experimental results of this method are compared with those obtained using an ideal sinusoidal current. Except for the second harmonic vibration, all other vibrations are significantly suppressed, with a maximum suppression rate of 92.28%. The total vibration level is reduced by 12.7619 dB, and the average torque is reduced by 0.67% with the total harmonic distortion of the current at 2.89%. The experimental results show that the vibration method in this paper has little influence on the average torque of the motor, the current distortion rate is small, and the vibration suppression effect is good.

Extremely rapid, yet noncatastrophic, preservation of the flattened-feathered and 3D dinosaurs of the Early Cretaceous of China

Northeast China's Early Cretaceous Yixian Formation preserves spectacular fossils that have proved extraordinarily important in testing evolutionary hypotheses involving the origin of birds and the distribution of feathers among nonavian dinosaurs. These fossils occur either flattened with soft tissue preservation (including feathers and color) in laminated lacustrine strata or as three-dimensional (3D) skeletons in "life-like" postures in more massive deposits. The relationships of these deposits to each other, their absolute ages, and the origin of the extraordinary fossil preservation have been vigorously debated for nearly a half century, with the prevailing view being that preservation was linked to violent volcanic eruptions or lahars, similar to processes that preserved human remains at Pompeii. We present high-precision zircon U-Pb geochronology from cores and outcrops, demonstrating that Yixian Formation accumulation rates are more than an order of magnitude higher than usually estimated. Additionally, we provide zircon provenance and sedimentological data from 3D dinosaur fossils, which imply that their death and burial occurred in collapsed burrows, rather than via a catastrophic volcanogenic mechanism. In the studied area, the three principal fossil-rich intervals of the Yixian occur as a cyclic sequence that correspond to periods of high precipitation. Using Bayesian-Markov Chain Monte Carlo approaches, we constrain the total duration of the sequence to less than ~93,000 y and suggest that climatic precession paced the expression of these cyclic sediments. Rather than representing multiple, Pompeii-like catastrophes, the Yixian Formation is instead a brief snapshot of normal life and death in an Early Cretaceous continental community.

Leveraging High-Resolution Ion Mobility-Mass Spectrometry for Cyclic Peptide Soft Spot Identification.

Cyclic peptides are an important class of molecules that gained significant attention in the field of drug discovery due to their unique pharmacological characteristics and enhanced proteolytic stability. Yet, gastrointestinal degradation remains a major hurdle in the discovery of orally bioavailable cyclic peptides. Soft spot identification (SSID) of the regions in the cyclic peptide sequence susceptible to amide hydrolysis by proteases is used in the discovery stage to guide medicinal chemistry design. SSID can be an arduous task, traditionally performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS), often resulting in complex and time-consuming manual analysis, particularly when isomeric linear peptide metabolites chromatographically coelute. Here, we present an alternative orthogonal approach that entails a high-resolution ion mobility (HRIM) system based on Structures for Lossless Ion Manipulation (SLIM) technology interfaced with quadrupole time-of-flight (QTOF) mass spectrometry to address some of the challenges associated with SSID. Two strategies were used to resolve linear isomeric peptide metabolites: labeled and label-free, both utilizing the HRIM platform. The label-free strategy leverages negative polarity to ionize the isomers which achieves better separation of the gas phase ions in the ion mobility (IM) dimension as compared to positive polarity, which is a more conventional approach when studying proteins and peptides. The second approach uses an isotope-labeled dimethyl tag on the terminal amine group, acting as a "shift reagent" to influence the mobility of isomers in the positive mode. This method resulted in baseline separation for the isomers of interest and produced unique product ions in the fragmentation spectra for unambiguous soft spot identification. Both label-free and labeled strategies demonstrated the ability to solve the challenges associated with SSID for cyclic peptides.

Study of non-exponential OSL decay curve within critical physical conditions of synthetic quartz material and their resolution by selection of suitable protocol

Researchers had reported that synthetic quartz which was annealed either at 400 °C irradiated by 75.6 Gy beta doses or at 600 °C irradiated by 25.2 Gy beta doses showed better rise in OSL intensity at room temperature depicting the change from non-exponential to exponential shape of the decay curve. Under these conditions, the non-exponential shape of decay curve with weaker OSL intensity was observed. It was due to re-trapping of optically released electrons by shallow traps corresponding to 110 °C TL glow peak and it was later verified by ESR spectra.In order to eliminate the non-exponential behaviour of decay curve, the researchers suggested OSL measurement at elevated temperature so as to further remove the contribution of shallow traps. However, in the present work, the OSL decay curves are recorded at 160 °C for 400 °C and 600 °C annealed samples irradiated by 2.52 Gy, 5.04 Gy, 25.2 Gy and 75.6 Gy beta doses. Both the samples show non-exponential shape of OSL decay curve up to 25.2 Gy beta doses. However, it gradually changes to exponential shape with better OSL intensity at higher beta doses. Additionally, few attempts were made to examine the non-exponential pattern of OSL decay at room temperature as well as elevated temperature within respective critical conditions by using fitting equations. It reports that various mode of non-exponential patterns of curve and their changes were influenced by strength of physical conditions. Further, a new protocol of cyclic sequence of doses, pre-heat up to 200 °C, test dose and stimulation at 125 °C for 40 s stimulation time was implemented to identical treated samples. It shows disappearance of non-exponential shape of OSL decay by growth in OSL intensity. These changes in OSL pattern were further justified by the contribution of annealing, irradiation, thermal transfer and thermal assistance process and TL measurements before and after OSL.

Evolution of in-situ pore structure of nanosilica modified high-volume blast furnace slag cementitious materials under sulfate attack

Nanosilica (NS) has been introduced to enhance the early strength and mitigate the porous structure issues associated with high-volume ground blast furnace slag (GGBS) cementitious materials (HVS). The impact of NS on the sulfate attack resistance in HVS cementitious materials is a noteworthy concern, especially concerning the degradation evolution process under sulfate attack. This study comprehensively analyzed the total volume changes and in-situ pore structure evolution for NS modified HVS cementitious materials under sulfate attack. The findings revealed that NS could effectively cause an increase in pores smaller than 100 nm and decrease in pores larger than 100 nm in HVS cementitious materials. Specifically, NS contributed to a reduction in volume expansion, weight loss, and surface damage of 80 wt% GGBS cement paste during sulfate attack. NS demonstrated its efficacy in improving the ability of 80 wt% GGBS cementitious materials to withstand expansion pressure caused by sulfate attack products, though NS did not significantly reduce the quantity of sulfate attack products. Conversely, NS led to an increase in volume expansion, weight loss and early damage of 60 wt% GGBS cement paste. The damage inflicted on cement paste under sulfate attack primarily manifested as the destruction of pores in nanometer. The process involved a cyclic sequence of pore filling, damage, refilling, and redamage during the sulfate attack process.

Spherical objects, transitivity and auto-equivalences of Kodaira cycles via gentle algebras

This paper studies the class of spherical objects over any Kodaira n -cycle of projective lines and provides a parametrization of their isomorphism classes in terms of closed curves on the n -punctured torus without self-intersections. Employing recent results on gentle algebras, we derive a topological model for the bounded derived category of any Kodaira cycle. The groups of triangle auto-equivalences of these categories are computed and are shown to act transitively on isomorphism classes of spherical objects. This answers a question by Polishchuk (2002) and extends earlier results by Burban–Kreußler (2012) and Lekili–Polishchuk (2019). The description of auto-equivalences is further used to establish faithfulness of a mapping class group action defined by Sibilla (2014). The final part describes the closed curves which correspond to vector bundles and simple vector bundles. This leads to an alternative proof of a result by Bodnarchuk–Drozd–Greuel (2012) which states that simple vector bundles on cycles of projective lines are uniquely determined by their multi-degree, rank and determinant. As a by-product, we obtain a closed formula for the cyclic sequence of any simple vector bundle on C_{n} as introduced by Burban–Drozd–Greuel (2001).

Development and Challenges of Cyclic Peptides for Immunomodulation.

Cyclic peptides are polypeptide chains formed by cyclic sequences of amide bonds between protein-derived or non-protein-derived amino acids. Compared to linear peptides, cyclic peptides offer several unique advantages, such as increased stability, stronger affinity, improved selectivity, and reduced toxicity. Cyclic peptide has been proved to have a promising application prospect in the medical field. In addition, this paper mainly describes that cyclic peptides play an important role in anti-cancer, anti-inflammatory, anti-virus, treatment of multiple sclerosis and membranous nephropathy through immunomodulation. In order to know more useful information about cyclic peptides in clinical research and drug application, this paper also summarizes cyclic peptides currently in the clinical trial stage and cyclic peptide drugs approved for marketing in the recent five years. Cyclic peptides have many advantages and great potential in treating various diseases, but there are still many challenges to be solved in the development process of cyclic peptides.

Influence of precast microbial reinforcement on lateral responses of monopiles

Microbially Induced Calcium Carbonate Precipitation (MICP) provides an environmentally friendly solution for reinforcing large diameter monopiles for offshore wind turbines (OWTs). This study presents an investigation into the lateral responses of monopiles with precast microbial reinforcement using a low-pH one-phase method. Both static and cyclic loading tests were carried out. The results of static loading tests show that the failure mode of the bio-reinforced monopile was an overall overturn failure. The lateral bearing capacity was increased by 50% and the bending moment was reduced by about 25% with the bio-reinforcement. Further investigation was conducted on the secant stiffness, damping ratio, and accumulated deformation of the bio-reinforced monopile under various cyclic loadings. With the bio-reinforcement, the accumulated deformation under one-way cyclic loading can be reduced by 30%–60%. The influences of cyclic loading parameters and loading sequence on pile stiffness were clarified. The growth ratio of pile stiffness due to bio-reinforcement under one-way loading was between 1.65 and 2.82, and decreased with increasing load amplitude. The ratio was smaller under two-way loading. Three competing factors on pile stiffness were identified: cyclic compaction of the unreinforced sandy soil, weakening of the bio-reinforced soil and soil subsidence around the bio-reinforced soil.

Topology optimization of the flat steel shear wall based on the volume constraint and strain energy assumptions under the seismic loading conditions

In structural engineering systems, shear walls are two-dimensional vertical elements designed to endure lateral forces acting in-plane, most frequently seismic and wind loads. Shear walls come in a variety of materials and are typically found in high-rise structures. Because steel shear walls are lighter, more ductile, and stronger than other concrete shear walls, they are advised for usage in steel constructions. It is important to remember that the steel shear wall has an infill plate, which can be produced in a variety of forms. The critical zones in flat steel shear walls are the joints and corners where the infill plate and frame meet. The flat infill plate can be modified to improve the strength and weight performance of the steel shear walls. One of these procedures is Topology Optimization (TO) and this method can reduce the weight and also, increase the strength against the cyclic loading sequences. In the current research paper, the TO of the infill steel plate was considered based on the two methods of volume constraint and maximization of strain energy. Four different volumes (i.e., 60%, 70%, 80%, and 90%) were assumed for the mentioned element in the steel shear wall. The obtained results revealed that the topology configuration of CCSSW with 90% volume constraint presented the highest seismic loading performance. The cumulated energy for this type of SSW was around 700 kJ while it was around 600 kJ for other topology optimization configurations.

Upregulation of the Urotensin II System in Diabetic Kidney Disease Includes Urotensin II-Related Peptide

The urotensin II (UII) system consists of endogenous ligands UII and its paralog urotensin II-related peptide (URP) and their receptor, UT. Originally isolated from the rat brain, URP is conserved across all vertebrates and shares the same cyclic hexapeptide core sequence with UII. However, UII and URP exhibit different N-terminal amino acid sequences. Beyond the central nervous system, UII and URP are functionally expressed in peripheral tissues. Alterations in tissue expression levels of UII and UT and blood or urinary UII concentrations have been associated with cardiovascular, pulmonary, and kidney dysfunctions, including hypertension, chronic heart failure, pulmonary hypertension, glomerulonephritis, and diabetes, making the UII system a potential therapeutic target for cardiovascular and kidney disease. The skeletal muscle and plasma levels of UII are increased in diabetic mice. Increased kidney tissue expression levels of UII and UT have also been demonstrated in humans and animals with diabetic kidney disease (DKD). Our recent work showed that UT is functionally expressed in cultured mouse glomerular mesangial cells (GMCs). Activation of UT by UII contributes to Ca2+-dependent GMC proliferation and extracellular matrix protein accumulation under high glucose conditions. We have also shown that DKD is attenuated in UT knockout mice. Despite the structural homology between UII and URP, studies have shown that the peptides may exhibit differential central and peripheral expression and pathophysiological function. However, whether URP is dysregulated in DKD remains unclear. Here, we examined whether URP production and kidney expression levels are altered in a hyperglycemic milieu and associated with DKD. Using a streptozotocin (STZ)-induced diabetes model, we examined the kidney tissue, plasma, and urinary levels of UII peptides. We also tested the hypothesis that, like UII, URP stimulates GMC proliferation and matrix protein synthesis. Our data show that protein and mRNA expression levels of both UII and URP were increased in the kidneys of hyperglycemic mice that developed albuminuria. Urinary and plasma UII and URP concentrations were also elevated in the mice. Although both UII and URP stimulated proliferation and type IV collagen production in cultured mouse GMCs by activating UT, the effect of UII was greater. Our data suggests that changes in the UII system in DKD are not limited to UII and UT but include the less-studied URP. GMC proliferation and extracellular matrix accumulation driven by UII and URP may contribute to DKD. NHLBI: R01 HL151735. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A Tag‐Free Platform for Synthesis and Screening of Cyclic Peptide Libraries

AbstractIn the realm of high‐throughput screening (HTS), macrocyclic peptide libraries traditionally necessitate decoding tags, essential for both library synthesis and identifying hit peptide sequences post‐screening. Our innovation introduces a tag‐free technology platform for synthesizing cyclic peptide libraries in solution and facilitates screening against biological targets to identify peptide binders through unconventional intramolecular CyClick and DeClick chemistries (CCDC) discovered through our research. This combination allows for the synthesis of diverse cyclic peptide libraries, the incorporation of various amino acids, and facile linearization and decoding of cyclic peptide binder sequences. Our sensitivity‐enhancing derivatization method, utilized in tandem with nano LC‐MS/MS, enables the sequencing of peptides even at exceedingly low picomolar concentrations. Employing our technology platform, we have successfully unearthed novel cyclic peptide binders against a monoclonal antibody and the first cyclic peptide binder of HIV capsid protein responsible for viral infections as validated by microscale thermal shift assays (TSA), biolayer interferometry (BLI) and functional assays.

A Tag-Free Platform for Synthesis and Screening of Cyclic Peptide Libraries.

In the realm of high-throughput screening (HTS), macrocyclic peptide libraries traditionally necessitate decoding tags, essential for both library synthesis and identifying hit peptide sequences post-screening. Our innovation introduces a tag-free technology platform for synthesizing cyclic peptide libraries in solution and facilitates screening against biological targets to identify peptide binders through unconventional intramolecular CyClick and DeClick chemistries (CCDC) discovered through our research. This combination allows for the synthesis of diverse cyclic peptide libraries, the incorporation of various amino acids, and facile linearization and decoding of cyclic peptide binder sequences. Our sensitivity-enhancing derivatization method, utilized in tandem with nano LC-MS/MS, enables the sequencing of peptides even at exceedingly low picomolar concentrations. Employing our technology platform, we have successfully unearthed novel cyclic peptide binders against a monoclonal antibody and the first cyclic peptide binder of HIV capsid protein responsible for viral infections as validated by microscale thermal shift assays (TSA), biolayer interferometry (BLI) and functional assays.

Transference for loose Hamilton cycles in random 3‐uniform hypergraphs

AbstractA loose Hamilton cycle in a hypergraph is a cyclic sequence of edges covering all vertices in which only every two consecutive edges intersect and do so in exactly one vertex. With Dirac's theorem in mind, it is natural to ask what minimum ‐degree condition guarantees the existence of a loose Hamilton cycle in a ‐uniform hypergraph. For and each , the necessary and sufficient such condition is known precisely. We show that these results adhere to a ‘transference principle’ to their sparse random analogues. The proof combines several ideas from the graph setting and relies on the absorbing method. In particular, we employ a novel approach of Kwan and Ferber for finding absorbers in subgraphs of sparse hypergraphs via a contraction procedure. In the case of , our findings are asymptotically optimal.

Sequences in finite fields yielding divisors of Mersenne, Fermat and Lehmer numbers, I

The aim of this work is to present a method using the cyclic sequences $\{M_k\},\{\theta_{t,k}\}$ and $\{\psi_{t,k} \}$ in the finite fields $\mathbb{F}_\rho$, with $\rho$ a prime, that yield divisors of Mersenne, Fermat and Lehmer numbers. The transformations $\tau_t$ and $\sigma_t$ are introduced which lead to the proof of the cyclic nature of the sequences $\{\theta_{t,k}\}$ and $\{\psi_{t,k}\}$. Results on the roots of the $H(x)$-polynomials in $\mathbb{F}_\rho$ form the central theme of the study.

Tetrazine cyclized peptides for one-bead-one-compound library: Synthesis and sequencing.

While most FDA-approved peptide drugs are cyclic, robust cyclization chemistry of peptides and the deconvolution of the cyclic peptide sequences using tandem mass spectrometry render cyclic peptide drug discovery difficult. In this chapter, the protocol for the successful synthesis of tetrazine-linked cyclic peptide library in solid phase, which shows both robust cyclization and easy sequence deconvolution, is described. The protocol for the linearization and cleavage of cyclic peptides from the solid phase by simple UV light irradiation, followed by accurate sequencing using tandem mass spectrometry, is described. We describe the troubleshooting for this dithiol bis-arylation reaction and for the successful cleavage of the aryl cyclic peptide into linear form. This method for efficient solid-phase macrocyclization can be used for the rapid production of loop-based peptides and screening for inhibition of protein-protein interactions, by using the covalent inverse electron-demand Diels Alder reaction to supplement the non-covalent interaction between a protein and its peptide binder, isolating highly selective peptides in the process.

Natural cycles in the Northern Baikal region

The authors of the article present the results of an analysis of the cyclicity of long-term numerical series of meteorological parameters (average annual air temperature, total annual precipitation) and six longterm numerical series of short-lived animal species from different taxonomic groups: ground beetles, small rodents and passerine birds living in similar biotopes of the low-mountain part of Barguzinsky ridge (territory of the Barguzin State Natural Biosphere Reserve). The cyclic components of long-term observation series lasting 33-67 years were studied by Fourier spectral analysis. Periodograms and cyclic sequences of model species coincide in most cases. In all species, high-frequency 2-3 year cycles predominate, while mid-frequency 4-8 year and low-frequency 9-19 year cycles are of secondary importance. Statistically significant correlations between cyclicity in the long-term abundance series of model animal species and the cyclicity of annual precipitation and average annual temperature have been identified. Reliable correlations between the cyclicity of Wolf numbers and the cyclicality of meteorological parameters are shown. Solar activity has an indirect effect on the cyclicity of natural processes in the Northern Baikal region.

Late Holocene evolution of a coastal barrier system at Bilene, Mozambique

AbstractThis research attempts to provide a contribution to the study on coastal barrier‐lagoons in the SE Africa generated by sea‐level fluctuations, and climate change during the Late Holocene. To achieve this goal, the grain‐size analysis and morphoscopic description helped to detect cyclic facie sequences with sediments sized over 200 μm mixed with silt, bioclasts and organic matter. Moreover, the magnetic susceptibility and X‐ray diffraction (XRD) analyses displayed over 90% of quartz and isolated mica, feldspar and heavy minerals. Additionally, the X‐ray fluorescence (XRF) results display the interplay between terrigenous (>Ti and Al) and marine influence (S, Cl and ~Ca) over the last ~3,500 cal. yrs. BP. The geochemical tracer fluctuations detected suggest five distinct deposits including beach, washover, lacustrine system, aeolian deflation that rest on top of the Pleistocene palaeodunes, which are tentatively associated with the sea‐level variations, extreme marine events or with local floods. Although the multiproxy data record refers to a study in Bilene‐Mozambique, it is interesting to understand the mechanisms and variables related to the evolutionary dynamics of coastal barrier lagoons generated by sea‐level fluctuations and climate change, especially in the SE Africa.

Continuous Wavelet Transformation to Quantify small-scale Cycles of Petrophysical Properties; a New Approach Applied in a Potential Disposal Repository of Nuclear Waste, SW Hungary

Continuous Wavelet Transformation (CWT) was applied to study the small-scale repetitive oscillations of porosity distribution patterns in a 5 m silty-claystone core sample of the Boda Claystone Formation. We handled the fluctuations in voxel porosity averages over unequal depth distributions as signals over uneven time intervals. The strength of wavelet analysis lies in the ability to study the fluctuation of a signal in detail, i.e., the wavelet transforms permit automatic localization of the cyclic attributes' sequences both in time (the depth domain) and according to their frequency (the frequency domain). Thereupon, three main frequency branches (cycles) were discerned: small scale (5, 6.67, and 11 cm), intermediate scale (20, 30 cm), and large scale (66.67 cm). Depending on the CWT coefficients magnitude plot, we were able to detect the developments of porosity oscillation according to the depth variable. Thus, small-scale cycles were seen throughout the core sample., the intermediate-scale cycles were strong in the upper parts of the core sample and dwindled toward greater depths, and the large cycle was predominant in the lower part of the core sample. The cross-correlation of the wavelet coefficients of porosity and rock-forming components allows a detailed study of the inter-dependence of such parameters as their relationship changes over time. The distinct peaks at zero lag indicates that the measured wavelet coefficient series were contemporaneously correlated; their strong positive correlations suggest that both examined series respond similarly and simultaneously to other exogenous factors. The results emphasize that cyclical porosity fluctuations at all scales would concern three main factors; sediment deposition, diagenetic processes, and structural deformation (i.e., convolute laminations).

Enhanced Neuron Growth and Electrical Activity by a Supramolecular Netrin-1 Mimetic Nanofiber.

Neurotrophic factors are essential not only for guiding the organization of the developing nervous system but also for supporting the survival and growth of neurons after traumatic injury. In the central nervous system (CNS), inhibitory factors and the formation of a glial scar after injury hinder the functional recovery of neurons, requiring exogenous therapies to promote regeneration. Netrin-1, a neurotrophic factor, can initiate axon guidance, outgrowth, and branching, as well as synaptogenesis, through activation of deleted in colorectal cancer (DCC) receptors. We report here the development of a nanofiber-shaped supramolecular mimetic of netrin-1 with monomers that incorporate a cyclic peptide sequence as the bioactive component. The mimetic structure was found to activate the DCC receptor in primary cortical neurons using low molar ratios of the bioactive comonomer. The supramolecular nanofibers enhanced neurite outgrowth and upregulated maturation as well as pre- and postsynaptic markers over time, resulting in differences in electrical activity similar to neurons treated with the recombinant netrin-1 protein. The results suggest the possibility of using the supramolecular structure as a therapeutic to promote regenerative bioactivity in CNS injuries.

Research on online and offline double-loop teaching of college students’ mental health education based on cluster analysis algorithm

Abstract In this paper, a knowledge difficulty clustering algorithm (MIBKPC) based on multidimensional time-series data and learning path networks is proposed. The algorithm integrates the cyclic learning sequence, forgetting behavior and system interaction degree formed by learners learning some of the more difficult knowledge points, and constructs a computational model for the difficulty similarity of knowledge points based on system interaction behavior so as to better portray the difficulty similarity of knowledge points based on system interaction behavior. Then a knowledge point difficulty clustering algorithm (MFSKPC) based on multidimensional time-series data and maximum frequent subgraphs is proposed. The algorithm extracts the maximum frequent subgraphs of the atlas based on the learner’s directed learning path atlas using the gSpan-based maximum frequent subgraph mining algorithm and portrays the difficulty similarity of knowledge points based on system interaction behaviors by combining the system interaction degree and the maximum frequent subgraphs. In the accuracy comparison, the clustering accuracy of the MFSKPC algorithm for advanced learners was higher than that of the MIBKPC algorithm for both K=3 and K =5 conditions by 7.89% and 8.29%, respectively. In the comparative analysis of double-loop psychological instruction, the experimental class improved its pre and post-test scores by an average of 2.38 points, while the control group improved by an average of only 1.88 points. The experiment showed that the double-loop teaching based on the MFSKPC algorithm was more effective.