Circulating tumor DNA in liquid biopsy: Current diagnostic limitation

With the rapid development of science and technology,cell-free DNA(cfDNA)is rapidly becoming an important biomarker for tumor diagnosis,monitoring and prognosis,and this cfDNA-based liquid biopsy technology has great potential to become an important part of precision medicine.cfDNA is the total amount of free DNA in the systemic circulation,including DNA fragments derived from tumor cells and all other somatic cells.Tumor cells release fragments of DNA into the bloodstream,and this source of cfDNA is called circulating tumor DNA(ctDNA).cfDNA detection has become a major focus in the field of tumor research in recent years,which provides a new opportunity for non-invasive diagnosis and prognosis of cancer.In this paper,we discuss the limitations of the study on the origin and dynamics analysis of ctDNA,and how to solve these problems in the future.Although the future faces major challenges,it also con-tains great potential.

THE SMOOTHING EFFECT IN SHARP GEVREY SPACE FOR THE SPATIALLY HOMOGENEOUS NON-CUTOFF BOLTZMANN EQUATIONS WITH A HARDPOTENTIAL

In this article, we study the smoothing effect of the Cauchy problem for the spatially homogeneous non-cutoff Boltzmann equation for hard potentials. It has long been suspected that the non-cutoff Boltzmann equation enjoys similar regularity properties as to whose of the fractional heat equation. We prove that any solution with mild regularity will become smooth in Gevrey class at positive time, with a sharp Gevrey index, depending on the angular singularity. Our proof relies on the elementary L^(2) weighted estimates.

Role of oncogenic long noncoding RNA KCNQ1OT1 in colon cancer

The role of lncRNA KCNQ1 opposite strand/antisense transcript 1(KCNQ1OT1)in colon cancer involves various tumorigenic processes and has been studed widely.However,the mechanism by which it promotes colon cancer remains unclear.Retrovirnl vector pSEB61 was retroftted in established HCT116 siKCN and SW480-siKCN cells to silence KCNQ1 OT1.Cellular proliferation was measured using CCK8 assay,and flow cytometry(FCM)detected cell cydle changes.RNA sequencing(RNA Seq)analysis showed differentially expressed genes(DEGs).Gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyses were carried out to analyze enriched functions and signaling pathways.RT-qPCR,immunofluorescence,and western blotting were carried out to validate downstream gene expressions.The effects of tumorigenesis were evaluated in BALB/c nude mice by tumor xenografts.Our data revealed that the silencing of KONQ1OT1 in HCT116 and SW480 cells slowed cell growth and decreased the number of cells in the G2/M phase.RNA-Seq analysis showed the data of DEGs enriched in various GO and KEGG pathways such as DNA replication and cell cyde.RT qPCR,immunofluorescence,and western blotting confirmed downstream CCNE2 and PCNA gene expressions.HCT116 siKCN cells signifcantly suppressed tumorigenesis in BALB/c nude mice.Our study suggests that lncRNA KCNQ1OT1 may provide a promising therapeutic strategy for colon cancer.

Anomaly-Resistant Decentralized State Estimation Under Minimum Error Entropy With Fiducial Points for Wide-Area Power Systems

This paper investigates the anomaly-resistant decentralized state estimation(SE) problem for a class of wide-area power systems which are divided into several non-overlapping areas connected through transmission lines. Two classes of measurements(i.e., local measurements and edge measurements) are obtained, respectively, from the individual area and the transmission lines. A decentralized state estimator, whose performance is resistant against measurement with anomalies, is designed based on the minimum error entropy with fiducial points(MEEF) criterion. Specifically, 1) An augmented model, which incorporates the local prediction and local measurement, is developed by resorting to the unscented transformation approach and the statistical linearization approach;2) Using the augmented model, an MEEF-based cost function is designed that reflects the local prediction errors of the state and the measurement;and 3) The local estimate is first obtained by minimizing the MEEF-based cost function through a fixed-point iteration and then updated by using the edge measuring information. Finally, simulation experiments with three scenarios are carried out on the IEEE 14-bus system to illustrate the validity of the proposed anomaly-resistant decentralized SE scheme.

Analysis of characteristic features in ultrasound diagnosis of fetal limb body wall complex during 11-13+6 weeks

BACKGROUND Limb body wall complex(LBWC)is a fatal malformation characterized by major defects in the fetal abdominal or thoracic wall,visceral herniation,significant scoliosis or spina bifida,limb deformities,craniofacial deformities,and umbilical cord abnormalities(short or absent umbilical cord).Early diagnosis of this condition is of great clinical significance for clinical intervention and pregnancy decision-making.With the rapid development of fetal ultrasound medicine,early pregnancy(11-13+6 wk)standardized prenatal ultrasound examinations have been widely promoted and applied.AIM To explore the value of prenatal ultrasound in the diagnosis of fetal LBWC syndrome during early pregnancy.METHODS The ultrasonographic data and follow-up results of 18 cases of fetal LBWC diagnosed by prenatal ultrasound during early pregnancy(11-13+6 wk)were retrospectively analyzed,and their ultrasonographic characteristics were analyzed.RESULTS Among the 18 fetuses with limb wall abnormalities,there were spinal dysplasia(18/18,100%),varying degrees of thoracoschisis and gastroschisis(18/18,100%),limb dysplasia in 6 cases(6/18,33%),craniocerebral malformations in 4 cases(4/18,22%),thickening of the transparent layer of the neck in 5 cases(5/18,28%),and umbilical cord abnormalities in 18 cases(18/18,100%),single umbilical artery in 5 cases.CONCLUSION Prenatal ultrasound in early pregnancy can detect LBWC as early as possible,and correct prenatal evaluation provides important guidance value for pregnancy decision-making and early intervention.

A Novel SE-CNN Attention Architecture for sEMG-Based Hand Gesture Recognition

In this article,to reduce the complexity and improve the generalization ability of current gesture recognition systems,we propose a novel SE-CNN attention architecture for sEMG-based hand gesture recognition.The proposed algorithm introduces a temporal squeeze-and-excite block into a simple CNN architecture and then utilizes it to recalibrate the weights of the feature outputs from the convolutional layer.By enhancing important features while suppressing useless ones,the model realizes gesture recognition efficiently.The last procedure of the proposed algorithm is utilizing a simple attention mechanism to enhance the learned representations of sEMG signals to performmulti-channel sEMG-based gesture recognition tasks.To evaluate the effectiveness and accuracy of the proposed algorithm,we conduct experiments involving multi-gesture datasets Ninapro DB4 and Ninapro DB5 for both inter-session validation and subject-wise cross-validation.After a series of comparisons with the previous models,the proposed algorithm effectively increases the robustness with improved gesture recognition performance and generalization ability.

Transcriptomic analysis of spinal cord regeneration after injury in Cynops orientalis

Cynops orientalis(C.orientalis)has a pronounced ability to regenerate its spinal cord after injury.Thus,exploring the molecular mechanism of this process could provide new approaches for promoting mammalian spinal cord regeneration.In this study,we established a model of spinal cord thoracic transection injury in C.orientalis,which is an endemic species in China.We performed RNA sequencing of the contused axolotl spinal cord at two early time points after spinal cord injury–during the very acute stage(4 days)and the subacute stage(7 days)–and identified differentially expressed genes;additionally,we performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses,at each time point.Transcriptome sequencing showed that 13,059 genes were differentially expressed during C.orientalis spinal cord regeneration compared with uninjured animals,among which 4273 were continuously downregulated and 1564 were continuously up-regulated.Down-regulated genes were most enriched in the Gene Ontology term“multicellular organismal process”and in the ribosome pathway at 10 days following spinal cord injury.We found that multiple genes associated with energy metabolism were down-regulated and multiple genes associated with the lysosome were up-regulated after spinal cord injury,indicating the importance of low metabolic activity during wound healing.Immune response-associated pathways were activated during the early acute phase(4 days),while the expression of extracellular matrix proteins such as glycosaminoglycan and collagen,as well as tight junction proteins,was lower at 10 days post-spinal cord injury than 4 days post-spinal cord injury.However,compared with 4 days post-injury,at 10 days post-injury neuroactive ligand-receptor interactions were no longer down-regulated,up-regulated differentially expressed genes were enriched in pathways associated with cancer and the cell cycle,and SHH,VIM,and Sox2 were prominently up-regulated.Immunofluorescence staining showed that glial fibrillary acidic protein was up-regulated in axolotl ependymoglial cells after injury,similar to what is observed in mammalian astrocytes after spinal cord injury,even though axolotls do not form a glial scar during regeneration.We suggest that low intracellular energy production could slow the rapid amplification of ependymoglial cells,thereby inhibiting reactive gliosis,at early stages after spinal cord injury.Extracellular matrix degradation slows cellular responses,represses the expression of neurogenic genes,and reactivates a transcriptional program similar to that of embryonic neuroepithelial cells.These ependymoglial cells act as neural stem cells:they migrate and proliferate to repair the lesion and then differentiate to replace lost glial cells and neurons.This provides the regenerative microenvironment that allows axon growth after injury.

AN INTEGRATION BY PARTS FORMULA FOR STOCHASTIC HEAT EQUATIONS WITH FRACTIONAL NOISE

In this paper,we establish the integration by parts formula for the solution of fractional noise driven stochastic heat equations using the method of coupling.As an application,we also obtain the shift Harnack inequalities.

Cutting Force Fluctuation Suppression and Error Homogenization of Noncircular Gear Hobbing Based on the Tool Shifting Method

The current research on noncircular hobbing mainly focuses on the linkage model and motion realization.However,the intermittent cutting characteristics of hobbing would increase uncertainties in the manufacturing process.In this paper,a hobbing machining model with tool-shifting characteristics was proposed to solve the problems of cutting force fluctuation and inconsistency of tooth profile envelope accuracy at different positions of the pitch curve in noncircular gear hobbing.Based on the unit cutting force coefficient method,the undeformed chip volume generated by interrupted cutting was used to characterize the fluctuation trend of the hobbing force.The fluctuation characteristics of the cutting force generated by different hobbing models were compared and analyzed.Using the equivalent gear tooth and hob slotting numbers,an analysis model of the tooth profile envelope error of the noncircular gear was constructed.Subsequently,the tooth profile envelope errors at different positions of the pitch curve were compared and analyzed based on the constructed model.The transmission structure of the electronic gearbox was constructed based on the proposed hobbing model,and the hobbing experiment was conducted based on the selfdeveloped noncircular gear CNC hobbing system.This paper proposes a hobbing method that can effectively suppress the fluctuation of the peak and whole circumference cutting force and reduce the maximum envelope error of the whole circumference gear teeth.

Whole-brain CT Perfusion at Admission and During Delayed Time-window Detects the Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage

Objective To evaluate the utility of computed tomography perfusion(CTP)both at admission and during delayed cerebral ischemia time-window(DCITW)in the detection of delayed cerebral ischemia(DCI)and the change in CTP parameters from admission to DCITW following aneurysmal subarachnoid hemorrhage.Methods Eighty patients underwent CTP at admission and during DCITW.The mean and extreme values of all CTP parameters at admission and during DCITW were compared between the DCI group and non-DCI group,and comparisons were also made between admission and DCITW within each group.The qualitative color-coded perfusion maps were recorded.Finally,the relationship between CTP parameters and DCI was assessed by receiver operating characteristic(ROC)analyses.Results With the exception of cerebral blood volume(P=0.295,admission;P=0.682,DCITW),there were significant differences in the mean quantitative CTP parameters between DCI and non-DCI patients both at admission and during DCITW.In the DCI group,the extreme parameters were significantly different between admission and DCITW.The DCI group also showed a deteriorative trend in the qualitative color-coded perfusion maps.For the detection of DCI,mean transit time to the center of the impulse response function(Tmax)at admission and mean time to start(TTS)during DCITW had the largest area under curve(AUC),0.698 and 0.789,respectively.Conclusion Whole-brain CTP can predict the occurrence of DCI at admission and diagnose DCI during DCITW.The extreme quantitative parameters and qualitative color-coded perfusion maps can better reflect the perfusion changes of patients with DCI from admission to DCITW.

Enhanced Degradation of Methyl Orange with CoFe_(2)O_(4)@Zeolite Catalyst as Peroxymonosulfate Activator:Performance and Mechanism

Reagents:PMS(KHSO_(5)·0.5KHSO_(4)·0.5K_(2)SO_(4),KHSO_(5)),MO,cobalt chloride(CoCl_(2)·6H_(2)O),ferric chloride(FeCl3·6H_(2)O),sodium metasilicate nonahydrate(Na_(2)SiO_(3)·9H_(2)O),methanol(MeOH),tert-butyl alcohol(TBA),p-Benzoquinone(p-BQ),furfuryl alcohol(FFA),sodium carbonate(Na_(2)CO_(3)),sodium sulfate(Na_(2)SO_(4)),sodium chloride(NaCl)and potassium phosphate monobasic(KH_(2)PO_(4))were purchased from Aladdin Reagent Co.,Ltd(Shanghai,China).Coal gangue were collected from Huainan,China.All chemicals above are analytical grade,and deionized water was used throughout all experiments.

Vinous-throated parrotbills breed in invasive smooth cordgrass habitat:Can native birds avoid the potential ecological trap?

Native animals are facing long-term coexistence with invasive plants worldwide,the impacts of which on animal behavior remain poorly known.Potential ecological traps could threaten native birds breeding in invasive plant habitats,but behavioral strategies for birds to avoid such risks are few concerned.The invasion of Smooth Cordgrass(Spartina alterniflra) has seriously varied the vegetation landscape in the coastal wetlands of eastern China,and affected the habitat selection of native birds.Here,we investigated the nesting and breeding characteristics of a common native passerine,the Vinous-throated Parrotbill(Sinosuthora webbiana),in habitats dominated by native Common Reed(Phragmites australis) and exotic cordgrass.We found that parrotbills could complete their breeding cycle in cordgrass habitat.Most nest failure was attributed to predation in native habitat but tide inundation in cordgrass habitat.However,the nest success rate and daily survival rate(DSR) in cordgrass habitat were higher.Moreover,nest height was markedly higher in cordgrass habitat and was the most important influencing variable(positively correlated with the DSR).These results suggest that cordgrass habitat is a potential ecological trap due to the tide inundation,but some parrotbills seem to effectively avoid this risk by increasing nest height.Our study reveals that a native passerine changes its nesting behavior to accommodate invasive plant habitat and highlights that habitat changes caused by invasive plants may drive the adaptive evolution of native animal behavior.The limitation of these results must be acknowledged for the small sample size,and there is a need for a larger sample and long-term data for further verification.

A novel synthesized prodrug of gemcitabine based on oxygen-free radical sensitivity inhibited the growth of lung cancer cells

In the present study,we introduced the H2O2-sensitive thiazolidinone moiety at the 4th amino group of gemcitabine(GEM)to synthesize a new target compound named GEM-ZZQ,and then we confirmed its chemical structure by nuclear magnetic resonance spectroscopy.We further confirmed that GEM-ZZQ had a good chemical stability in different pH solutions in vitro and that it could be activated by H2O2 to release GEM.Pharmacodynamic studies revealed that the growth inhibition of human normal epithelial cells was weaker by GEM-ZZQ than by GEM treatment and that the inhibition of various lung cancer cell lines by GEM-ZZQ was similar to that of GEM.For the lung cancer cell lines that are resistant to the epidermal growth factor receptor(EGFR)-targeting inhibitor osimertinib,GEM-ZZQ showed less growth inhibition than GEM;however,GEM-ZZQ in combination with cisplatin showed better synergistic effects than GEM in the low-dose groups.In summary,we provided a new anti-cancer compound GEM-ZZQ for treating lung cancer by modifying the GEM structure.

Correlation between pre-treatment serum total blood bilirubin andunconjugated bilirubin and prognosis in patients with colorectalcancer

BACKGROUND Epidemiological studies have found that unconjugated bilirubin(UCB)levels are positively correlated with the incidence of colorectal cancer(CRC).Therefore,bilirubin may also play an important role in the prognosis of CRC.AIM To investigate the predictive value of total bilirubin(TBIL)and UCB in the prognosis of patients with CRC.METHODS A total of 142 CRC patients were selected as the research subjects in Jingxian Hospital,from October 2014 to May 2021.General and tumour-related clinical data at admission and the overall survival at 3 years after surgery were collected.The optimal cut-off values of TBIL and UCB were determined by receiver operating characteristic curve analysis.Univariate and multivariate Cox regression were used to analyse the effect of bilirubin level on the survival of CRC patients.The Kaplan–Meier method was used to assess the survival time.RESULTS The 3-year overall survival rate of CRC patients was significantly higher in the high TBIL(>13.45μmol/L)group than in the low TBIL(≤13.45μmol/L)group(76.4%vs 37.1%;P<0.05).The 3-year overall survival rate of CRC patients in the high UCB(>10.75μmol/L)group was significantly higher than that in the low UCB(≤10.75μmol/L)group(83.3%vs 34.2%;P<0.05).Multivariate Cox regression analysis showed that higher TBIL levels were an independent predictor of better prognosis in CRC patients(hazard ratio=0.360,95%confidence interval:0.159-0.812,P=0.014).CONCLUSION TBIL levels can be used as a prognostic indicator for CRC patients.

An amorphous manganese iron oxide hollow nanocube cathode for aqueous zinc ion batteries

Aqueous zinc ion batteries(ZIBs) are attracting considerable attentions for practical energy storage because of their low cost and high safety.Nevertheless,the traditional manganese oxide cathode materials suffer from the low intrinsic electronic conductivity,sluggish ions diffusion kinetics,and structural collapse,hindering their large-scale application.Herein,we successfully developed a latent amorphous Mn_(1.8)Fe_(1.2)O_(4) hollow nanocube(a-H-MnFeO) cathode material derived from Prussian blue analogue precursor.The amorphous nature endows the cathode with lower diffusion barrier and narrower band gap compared with crystalline counterpart,resulting in the superior Zn^(2+) ions and electrons transport kinetics.Hollow structure can furnish abundant surface sites and suppress the structural collapse during the repeated charge/discharge processes.By virtue of the multiple advantageous features,the a-H-MnFeO cathode exhibits exceptional electrochemical performance,in terms of high capacity,excellent rate capability,and prolonged cycle life.This strategy will pave the way for the structural design of emerging cathode materials.

A molecular probe carrying anti-tropomyosin 4 for early diagnosis of cerebral ischemia/reperfusion injury

In vivo imaging of cerebral ischemia/reperfusion injury remains an important challenge.We injected porous Ag/Au@SiO_(2) bimetallic hollow nanoshells carrying anti-tropomyosin 4 as a molecular probe into mice with cerebral ischemia/reperfusion injury and observed microvascular changes in the brain using photoacoustic imaging with ultrasonography.At each measured time point,the total photoacoustic signal was significantly higher on the affected side than on the healthy side.Twelve hours after reperfusion,cerebral perfusion on the affected side increased,cerebrovascular injury worsened,and anti-tropomyosin 4 expression increased.Twenty-four hours after reperfusion and later,perfusion on the affected side declined slowly and stabilized after 1 week;brain injury was also alleviated.Histopathological and immunohistochemical examinations confirmed the brain injury tissue changes.The nanoshell molecular probe carrying anti-tropomyosin 4 has potential for use in early diagnosis of cerebral ischemia/reperfusion injury and evaluating its progression.

Linolenic acid-metronidazole inhibits the growth of Helicobacter pylori through oxidation

BACKGROUND Resistance to antibiotics is one the main factors constraining the treatment and control of Helicobacter pylori(H.pylori)infections.Therefore,there is an urgent need to develop new antimicrobial agents to replace antibiotics.Our previous study found that linolenic acid-metronidazole(Lla-Met)has a good antibacterial effect against H.pylori,both antibiotic-resistant and sensitive H.pylori.Also,H.pylori does not develop resistance to Lla-Met.Therefore,it could be used for preparing broad-spectrum antibacterial agents.However,since the antibacterial mechanism of Lla-Met is not well understood,we explored this phenomenon in the present study.AIM To understand the antimicrobial effect of Lla-Met and how this could be applied in treating corresponding infections.METHODS H.pylori cells were treated with the Lla-Met compound,and the effect of the compound on the cell morphology,cell membrane permeability,and oxidation of the bacteria cell was assessed.Meanwhile,the differently expressed genes in H.pylori in response to Lla-Met treatment were identified.RESULTS Lla-Met treatment induced several changes in H.pylori cells,including roughening and swelling.In vivo experiments revealed that Lla-Met induced oxidation,DNA fragmentation,and phosphatidylserine ectropionation in H.pylori cells.Inhibiting Lla-Met with L-cysteine abrogated the above phenomena.Transcriptome analysis revealed that Lla-Met treatment up-regulated the expression of superoxide dismutase SodB and MdaB genes,both anti-oxidation-related genes.CONCLUSION Lla-Met kills H.pylori mainly by inducing oxidative stress,DNA damage,phosphatidylserine ectropionation,and changes on cell morphology.

Numerical Simulation of Droplet Generation in Coaxial Microchannels

In this study,numerical simulations of the pinching-off phenomena displayed by the dispersed phase in a continuous phase have been conducted using COMSOL Multiphysics(level-set method).Four flow patterns,namely“drop flow”,“jet flow”,“squeeze flow”,and“co-flow”,have been obtained for different flow velocity ratios,channel diameter ratios,density ratios,viscosity ratios,and surface tension.The flow pattern map of two-phase flow in coaxial microchannels has been obtained accordingly,and the associated droplet generation process has been critically discussed considering the related frequency,diameter,and pinch-off length.In particular,it is shown that the larger the flow velocity ratio,the smaller the diameter of generated droplets and the shorter the pinch-off length.The pinch-off length of a droplet is influenced by the channel diameter ratio and density ratio.The changes in viscosity ratio have a negligible influence on the droplet generation pinching frequency.With an increase in surface tension,the frequency of generation and pinch-off length of droplets decrease,but for small surface tension the generation diameter of droplet increases.

Comprehensive analysis of clinical and biological value of ING family genes in liver cancer

BACKGROUND Liver cancer(LIHC)is a malignant tumor that occurs in the liver and has a high mortality in cancer.The ING family genes were identified as tumor suppressor genes.Dysregulated expression of these genes can lead to cell cycle arrest,senescence and/or apoptosis.ING family genes are promising targets for anticancer therapy.However,their role in LIHC is still not well understood.AIM To have a better understanding of the important roles of ING family members in LIHC.METHODS A series of bioinformatics approaches(including gene expression analysis,genetic alteration analysis,survival analysis,immune infiltration analysis,prediction of upstream microRNAs(miRNAs)and long noncoding RNAs(lncRNAs)of ING1,and ING1-related gene functional enrichment analysis)was applied to study the expression profile,clinical relationship,prognostic significance and immune infiltration of ING in LIHC.The relationship between ING family genes expression and tumor associated immune checkpoints was investigated in LIHC.The molecular mechanism of ING1 mediated hepatocarcinogenesis was preliminarily discussed.RESULTS mRNA/protein expression of different ING family genes in LIHC was analyzed in different databases,showing that ING family genes were highly expressed in LIHC.In 47 samples from 366 LIHC patients,the ING family genes were altered at a rate of 13%.By comprehensively analyzing the expression,clinical pathological parameters and prognostic value of ING family genes,ING1/5 was identified.ING1/5 was related to poor prognosis of LIHC,suggesting that they may play key roles in LIHC tumorigenesis and progression.One of the target miRNAs of ING1 was identified as hsa-miR-214-3p.Two upstream lncRNAs of hsa-miR-214-3p,U91328.1,and HCG17,were identified.At the same time,we found that the expression of ING family genes was correlated with immune cell infiltration and immune checkpoint genes.CONCLUSION This study lays a foundation for further research on the potential mechanism and clinical value of ING family genes in the treatment and prognosis of LIHC.

Dynamic Characteristics of Functionally Graded Timoshenko Beams by Improved Differential Quadrature Method

This study proposes an effective method to enhance the accuracy of the Differential Quadrature Method(DQM)for calculating the dynamic characteristics of functionally graded beams by improving the form of discrete node distribution.Firstly,based on the first-order shear deformation theory,the governing equation of free vibration of a functionally graded beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam axial displacement,transverse displacement,and cross-sectional rotation angle by considering the effects of shear deformation and rotational inertia of the beam cross-section.Then,ignoring the shear deformation of the beam section and only considering the effect of the rotational inertia of the section,the governing equation of the beam is transformed into the eigenvalue problem of ordinary differential equations with respect to beam transverse displacement.Based on the differential quadrature method theory,the eigenvalue problem of ordinary differential equations is transformed into the eigenvalue problem of standard generalized algebraic equations.Finally,the first several natural frequencies of the beam can be calculated.The feasibility and accuracy of the improved DQM are verified using the finite element method(FEM)and combined with the results of relevant literature.