Biomimeitc Design of a Stubble-Cutting Disc Using Finite Element Analysis

Mole rat （Scaptochirus moschatus）, a soil-burrowing mammal, can efficiently dig soil using its fore claws. The profile curves of its claw toe provide excellent structure for digging. In this paper, a biomimetic stubble-cutting disc was designed by learning from the geometrical characteristics of the mole rat claw toes. To compare the structural strength and working eff^- ciency of the biomimetic disc and the conventional stubble-cutting disc, three-dimensional （3D） models of the discs were built and numerical analyzed in ABAQUS. In the dynamic soil cutting model, soil was modeled as an elastic-plastic material with elastic parameters, including Young＇s modulus, Poisson＇s ratio and Drucker-Prager criterion, which were obtained from triaxial tests. A general contact algorithm was used to simulate the interaction between rotary disc and soil. In FEA models, for the combined action of normal and friction stresses, the stress on the biomimetic disc is 34.33% lower than that of the conventional disc. For only the normal stress, the stress on the biomimetic disc is 22.64% lower than that on the conventional one. The magnitude of soil stress in biomimetie disc cutting model is 6.87% higher than that in conventional disc. The FEA results indicate that the biomimetic disc performs better in structural strength and cutting efficiency.

基于性格分析DISC理论的临床带教模式对护生核心能力的影响

目的:探讨基于性格分析DISC理论的临床带教模式对护生核心能力的影响。方法:选取2022年1月-12月在江苏省某三级甲等医院全科医学科的96名实习护生为研究对象,根据实习先后顺序分为试验组48人和对照组48人。在临床带教过程中,对照组实施传统带教方法,试验组实施基于性格分析DISC理论的临床带教模式,比较两组的核心能力、理论成绩、护理技能操作成绩、带教管理质量及带教满意度。结果:干预结束后,试验组核心能力、理论成绩、护理技能操作成绩、带教管理质量总分均高于对照组(P<0.05)。结论:将性格分析DISC理论应用于临床实习带教中,有利于培养护生的核心能力和提高其理论成绩、护理技能操作成绩及带教管理质量。

An Improved Deep Learning Framework for Automated Optic Disc Localization and Glaucoma Detection

Glaucoma disease causes irreversible damage to the optical nerve and it has the potential to cause permanent loss of vision.Glaucoma ranks as the second most prevalent cause of permanent blindness.Traditional glaucoma diagnosis requires a highly experienced specialist,costly equipment,and a lengthy wait time.For automatic glaucoma detection,state-of-the-art glaucoma detection methods include a segmentation-based method to calculate the cup-to-disc ratio.Other methods include multi-label segmentation networks and learning-based methods and rely on hand-crafted features.Localizing the optic disc(OD)is one of the key features in retinal images for detecting retinal diseases,especially for glaucoma disease detection.The approach presented in this study is based on deep classifiers for OD segmentation and glaucoma detection.First,the optic disc detection process is based on object detection using a Mask Region-Based Convolutional Neural Network(Mask-RCNN).The OD detection task was validated using the Dice score,intersection over union,and accuracy metrics.The OD region is then fed into the second stage for glaucoma detection.Therefore,considering only the OD area for glaucoma detection will reduce the number of classification artifacts by limiting the assessment to the optic disc area.For this task,VGG-16(Visual Geometry Group),Resnet-18(Residual Network),and Inception-v3 were pre-trained and fine-tuned.We also used the Support Vector Machine Classifier.The feature-based method uses region content features obtained by Histogram of Oriented Gradients(HOG)and Gabor Filters.The final decision is based on weighted fusion.A comparison of the obtained results from all classification approaches is provided.Classification metrics including accuracy and ROC curve are compared for each classification method.The novelty of this research project is the integration of automatic OD detection and glaucoma diagnosis in a global method.Moreover,the fusion-based decision system uses the glaucoma detection result obtained using several convolutional deep neural networks and the support vector machine classifier.These classification methods contribute to producing robust classification results.This method was evaluated using well-known retinal images available for research work and a combined dataset including retinal images with and without pathology.The performance of the models was tested on two public datasets and a combined dataset and was compared to similar research.The research findings show the potential of this methodology in the early detection of glaucoma,which will reduce diagnosis time and increase detection efficiency.The glaucoma assessment achieves about 98%accuracy in the classification rate,which is close to and even higher than that of state-of-the-art methods.The designed detection model may be used in telemedicine,healthcare,and computer-aided diagnosis systems.

Thermal fatigue and wear of compacted graphite iron brake discs with various thermomechanical properties

The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake discs.In this work,the thermal fatigue and wear of compacted graphite iron brake discs were investigated,aiming to provide an experimental foundation for achieving a balance between their thermal and mechanical properties.Compacted graphite iron brake discs with different tensile strengths,macrohardnesses,specific heat capacities and thermal diffusion coefficients were produced by changing the proportion and strength of ferrite.The peak temperature,pressure load and friction coefficient of compacted graphite iron brake discs were analyzed through inertia friction tests.The morphology of thermal cracks and 3D profiles of the worn surfaces were also discussed.It is found that the thermal fatigue of compacted graphite iron discs is determined by their thermal properties.A compacted graphite iron with the highest specific heat capacity and thermal diffusion coefficient exhibits optimal thermal fatigue resistance.Oxidization of the matrix at low temperatures significantly weakens the function of alloy strengthening in hindering the propagation of thermal cracks.Despite the reduced hardness,increasing the ferrite proportion can mitigate wear loss resulting from low disc temperatures and the absence of abrasive wear.

Birth Defects of the Child Optic Disc: Diagnostic Challenges and Prospects for Care

Introduction: Congenital optic disc anomalies in children refer to structural variations of the optic nerve head present from birth. These deformations involve the size, shape, color, and vessels of the optic disc. Although often asymptomatic, these anomalies can impact the visual development of the child, underscoring the importance of a thorough fundus examination for early detection and appropriate medical follow-up. We present two cases of congenital optic disc anomalies in children, illustrating the diagnostic challenges and complexity of their management. Case 1: A 3-year-old girl presented with a white spot in her left eye present since birth. Uncorrected distance visual acuity was 2/10 in the right eye, while she could perceive hand movements at 2 meters with the left eye. Normal examination in the right eye showed leukocoria, microphthalmia, and a white mass at the center of the optic disc on fundus examination in the left eye. Ocular imaging, including ultrasound and optical coherence tomography (OCT), confirmed the diagnosis of persistent hyperplastic primary vitreous (PHPV) in its mixed form in the left eye. Management included prescribing full optical correction and functional rehabilitation, without resorting to surgery. The course was marked by persistent amblyopia leading to a poor prognosis. Case 2: A 7-year-old girl consulted for vision disturbance in her right eye. Visual acuity was finger counting at 2 meters in the right eye and 10/10 in the left eye. Anterior segment examination revealed no abnormalities in both eyes. However, fundus examination highlighted a large funnel-shaped excavation associated with central glial proliferation, wheel spoke vessels, and neuroretinal ring atrophy in the right eye. Optical coherence tomography (OCT) of the right eye confirmed the diagnosis of isolated unilateral Morning Glory syndrome. Management included full optical correction and orthoptic rehabilitation. The course was marked by the absence of ocular complication and maintenance of visual stability in the right eye. The prognosis seemed favorable. Conclusion: Congenital optic disc anomalies in children exhibit great clinical variability and require an individualized diagnostic and therapeutic approach.

A Dual Closed-Loop Digital Twin Construction Method for Optimizing the Copper Disc Casting Process

The copper disc casting machine is core equipment for producing copper anode plates in the copper metallurgy industry.The copper disc casting machine casting package motion curve(CPMC) is significant for precise casting and efficient production.However,the lack of exact casting modeling and real-time simulation information severely restricts dynamic CPMC optimization.To this end,a liquid copper droplet model describes the casting package copper flow pattern in the casting process.Furthermore,a CPMC optimization model is proposed for the first time.On top of this,a digital twin dual closed-loop self-optimization application framework(DT-DCS) is constructed for optimizing the copper disc casting process to achieve self-optimization of the CPMC and closed-loop feedback of manufacturing information during the casting process.Finally,a case study is carried out based on the proposed methods in the industrial field.

Single atom Cu-N-C catalysts for the electro-reduction of CO_(2) to CO assessed by rotating ring-disc electrode

The electrochemical CO_(2) reduction reaction(CO_(2)RR) to controllable chemicals is considered as a promising pathway to store intermittent renewable energy. Herein, a set of catalysts based on copper-nitrogendoped carbon xerogel(Cu-N-C) are successfully developed varying the copper amount and the nature of the copper precursor, for the efficient CO_(2)RR. The electrocatalytic performance of Cu-N-C materials is assessed by a rotating ring-disc electrode(RRDE), technique still rarely explored for CO_(2)RR. For comparison, products are also characterized by online gas chromatography in a H-cell. The as-synthesized Cu-NC catalysts are found to be active and highly CO selective at low overpotentials(from -0.6 to -0.8 V vs.RHE) in 0.1 M KHCO_(3), while H_(2) from the competitive water reduction appears at larger overpotentials(-0.9 V vs. RHE). The optimum copper acetate-derived catalyst containing Cu-N_(4) moieties exhibits a CO_(2)-to-CO turnover frequency of 997 h^(-1) at -0.9 V vs. RHE with a H_(2)/CO ratio of 1.8. These results demonstrate that RRDE configuration can be used as a feasible approach for identifying electrolysis products from CO_(2)RR.

Automated evaluation of parapapillary choroidal microvasculature in crowded optic discs:a controlled,optical coherence tomography angiography study

AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control subjects were enrolled in the study.One eye of each individual was included and OCT-A scans of optic discs were obtained in a 4.5×4.5 mm^(2) rectangular area.Radial peripapillary capillary(RPC)density,peripapillary retinal nerve fiber layer(pRNFL)thickness,cup volume,rim area,disc area,cup-to-disc(c/d)area ratio,and vertical c/d ratio were obtained automatically using device software.Automated parapapillary choroidal microvasculature(PPCMv)density was calculated using MATLAB software.When the vertical c/d ratio of the optic disc was absent or small cup,it was considered as a crowded disc.RESULTS:The mean signal strength index of OCT-A images was similar between the crowded discs and control eyes(P=0.740).There was no difference in pRNFL between the two groups(P=0.102).There were no differences in RPC density in whole image(P=0.826)and peripapillary region(P=0.923),but inside disc RPC density was higher in crowded optic discs(P=0.003).The PPCMv density in the inner-hemisuperior region was also lower in crowded discs(P=0.026).The pRNFL thickness was positively correlated with peripapillary RPC density(r=0.498,P<0.001).The inside disc RPC density was negatively correlated with c/d area ratio(r=-0.341,P=0.002).CONCLUSION:The higher inside disc RPC density and lower inner-hemisuperior PPCMv density are found in eyes with crowded optic discs.

Refined Anam-Net:Lightweight Deep Learning Model for Improved Segmentation Performance of Optic Cup and Disc for Glaucoma Diagnosis

In this work,we aim to introduce some modifications to the Anam-Net deep neural network(DNN)model for segmenting optic cup(OC)and optic disc(OD)in retinal fundus images to estimate the cup-to-disc ratio(CDR).The CDR is a reliable measure for the early diagnosis of Glaucoma.In this study,we developed a lightweight DNN model for OC and OD segmentation in retinal fundus images.Our DNN model is based on modifications to Anam-Net,incorporating an anamorphic depth embedding block.To reduce computational complexity,we employ a fixed filter size for all convolution layers in the encoder and decoder stages as the network deepens.This modification significantly reduces the number of trainable parameters,making the model lightweight and suitable for resource-constrained applications.We evaluate the performance of the developed model using two publicly available retinal image databases,namely RIM-ONE and Drishti-GS.The results demonstrate promising OC segmentation performance across most standard evaluation metrics while achieving analogous results for OD segmentation.We used two retinal fundus image databases named RIM-ONE and Drishti-GS that contained 159 images and 101 retinal images,respectively.For OD segmentation using the RIM-ONE we obtain an f1-score(F1),Jaccard coefficient(JC),and overlapping error(OE)of 0.950,0.9219,and 0.0781,respectively.Similarly,for OC segmentation using the same databases,we achieve scores of 0.8481(F1),0.7428(JC),and 0.2572(OE).Based on these experimental results and the significantly lower number of trainable parameters,we conclude that the developed model is highly suitable for the early diagnosis of glaucoma by accurately estimating the CDR.

Clinical therapeutic effect of self-prescribed Sanhanchushi Tongbi on lumbar disc herniation

BACKGROUND Lumbar disc herniation(LDH)commonly occurs during spinal surgery;LDH is on the increase in younger patients and is classified as"paralysis"and"back pain."Sanhanchushi Tongbi(SPST)is a customized prescription.It disperses cold,relieves pain,removes cold from the meridians and viscera,and treats neuropathic pain.However,few studies have investigated its mechanism of pain relief.AIM To observe the clinical therapeutic effects on LDH treated with self-prescribed SPST.METHODS A total of 211 patients with LDH syndrome were divided into two groups:107 patients in the control group were treated with conventional massage combined with traction,and 104 patients in the observation group were treated with a combination of the control regimen and self-prescribed oral SPST.The patients were treated for 4 wk.Indices of traditional Chinese medicine(TCM)syndrome score and serum inflammatory factor levels were measured.RESULTS After therapy,the TCM syndrome score in the observation group was significantly lower than that in the control group(P<0.05).The main symptoms,clinical signs,daily activities,and Japanese Orthopedic Association scores in the observation group were significantly higher than those in the control group after therapy(P<0.05).The levels of tumor necrosis factor-α,interleukin-6,and C-reactive protein were lower in the observation group than in the control group(P<0.05).In the observation group,superoxide dismutase levels were significantly higher,whereas malondialdehyde levels were significantly lower,compared with the control group(P<0.05).The overall efficacy rate in the observation group was 96.15%,which was substantially higher than that in the control group(88.79%;P<0.05).CONCLUSION Self-prescribed SPST can reduce the levels of inflammatory and pain-causing factors as well as lumbar pain in patients with LDH.

A meta-analysis on the clinical efficacy of fire dragon cupping in the treatment of lumbar disc herniation

Background:The incidence of lumbar disc herniation(LDH)is notably high.Consensus among experts highlights non-surgical treatments as the primary therapeutic approach for LDH.Contemporary medicine frequently employs pharmacotherapy and epidural injections in such treatments,which are associated with numerous adverse effects.Prolonged use can severely impair the liver and kidney functions of patients.Hence,the role of safe and effective traditional Chinese medicine techniques becomes pivotal.Among various traditional Chinese medicine approaches for treating LDH,fire dragon cupping,renowned for its remarkable efficacy,cost-effectiveness,and ease of application,is extensively utilised in clinical settings for managing LDH.Nonetheless,there is a scarcity of systematic and standardised evidence from evidence-based medicine studies.Therefore,conducting a meta-analysis is imperative.Methods:A comprehensive computerised search was conducted in databases including China National Knowledge Infrastructure,WanFang Data,VIP,China Biology Medicine disc,PubMed,EMbase,The Cochrane Library,Web of Science,and CINAHL.The search aimed to gather randomised controlled trials on fire dragon cupping therapy for LDH,spanning from the inception of these databases until December 2023.Two researchers independently screened the literature according to inclusion and exclusion criteria,extracted data,and assessed the methodological quality of the studies included,utilising RevMan 5.3 software for meta-analysis.Results:The results show that the fire dragon cupping therapy group had better clinical effectiveness(relative risk=1.23,95%confidence interval(CI)(1.14,1.33),P<0.00001),less pain(standardized mean difference=–1.33,95%CI(–1.49,–1.16),P<0.00001),and some improvement in lumbar function(Japanese Orthopaedic Association scores:mean difference=3.37,95%CI(2.31,4.43),P<0.00001.Conclusion:The fire dragon cupping therapy significantly alleviates LDH,warranting its extensive application.However,considering the limitations in the number and quality of studies included,the aforementioned conclusion necessitates further validation through more high-quality research.

Muscle Strength, Lumbar Curve, Fear of Movement and Functional Disability among Patients with Lumbar Disc Herniation: A Review

Introduction: Lumbar disc herniation (LDH) refers to the rupture of the fibrous annulus of the intervertebral discs. Lumbar curvature may lead to the occurrence of lumbar disc degeneration. Fear of movement may worsen their disc herniation and cause further pain and injury. LDH conditions impact the individuals’ quality of life, to explore the relationship between lumbar curve, muscle strength, fear of movement and functional disability among patients with LDH. Methods: An electronic search was conducted on PubMed, Medline, Science Direct, Springerlink, Google Scholar and a hand search from reference lists was reviewed. Publications were included in human studies, patients 25 - 85 years of age, original studies and published in English language journals from January 2002 to December 2023. Result: In total, 64 articles were researched through the online search engines, and 9 papers were found through manual searches of reference lists. As a result, a total of 11 articles were included for the purpose of this review. The comprehensive analysis revealed the presence of eight cross-sectional studies, two retrospective studies and one experimental study. A minimum of 25 participants and a maximum of 360 participants were included. Ten studies included both genders, only one studies included healthy adults and patients with LDH but these studies didn’t mention gender. Results showed that the factors influencing LDH can be categorized into non-modifiable factors, such as gender, age, height or others. Modifiable factors included increased BMI, DM, smoking, alcohol, employment status, lifestyle and health problems or psychology. Conclusion: Females with greater VASC may be at risk of LDH. The lumbar extensor muscles indicated a localized disc herniation or nerve root pathology in patients with LDH. The fear of movement may lead to psychological consequences and reduce functional disability among patients with LDH.

基于DISC性格类型的健康教育在分娩镇痛产妇纠正枕后位/枕横位中的应用观察

目的研究基于DISC性格类型的健康教育在分娩镇痛产妇采用自由体位纠正枕后位/枕横位中的应用效果。方法选取2022年3—12月在新泰市人民医院产科住院的确诊枕后位/枕横位分娩镇痛产妇80例,根据健康教育方式的不同分为2组,每组40例。对照组给予常规产程中健康教育,观察组给予基于DISC性格类型的健康教育,比较2组产妇自由体位依从性、产程时间、会阴侧切率、胎吸助产率、中转剖宫产率、产后出血率、护理满意度和新生儿窒息率。结果观察组自由体位依从性高于对照组(P<0.05),观察组第一、第二产程时间短于对照组(P<0.05),观察组会阴侧切率、中转剖宫产率、产后出血率均低于对照组(P<0.05),观察组护理满意度显著高于对照组(P<0.05)。结论基于DISC性格类型的健康教育应用于分娩镇痛产妇采用自由体位纠正枕后位/枕横位,不仅能提高产妇自由体位依从性,发挥自由体位优势,缩短产程时间,降低会阴侧切率、剖宫产率和产后出血率,提高分娩质量,还能提高护理满意度,值得临床进一步推广。

Research Progress on Conservative Treatment of Lumbar Disc Herniation

Lumbar disc herniation(LDH)is a common orthopedic disease in clinical practice,with main symptoms of varying degrees of pain and functional impairment,seriously affecting the quality of work and life of patients,and also causing a certain degree of economic burden to the patient's family and society.At present,there are various conservative treatment methods for LDH in clinical practice.Conservative treatment has the characteristics of small trauma and high safety,which can achieve symptom relief and cure for most patients in clinical practice.This article aims to provide a scientific reference for the selection of treatment plans for LDH patients by reviewing relevant literature on conservative treatment of LDH that has been publicly reported both domestically and internationally in recent years.

Effect of Articular Cavity Injection Combined with Bite Splint Treatment on Anterior Disc Displacement Without Reduction

Objective:To observe the clinical effect of articular cavity injection combined with bite splint therapy for the treatment of anterior disc displacement without reduction(ADDWoR).Methods:The research subjects for this study were 30 patients with ADDWoR treated in the temporomandibular joint specialist outpatient clinic from November 2018 to November 2019,with a disease duration of 1 to 6 months.The treatment group was treated with an articular cavity injection of sodium hyaluronate+bite splint.The control group was treated with a simple articular cavity injection of sodium hyaluronate.The two groups were followed up once every 2 weeks to evaluate the treatment effect and observe the clinical efficacy of the two groups.Statistical analysis was carried out using SPSS 24.0.t-test and general linear regression analysis were carried out to compare the data of both groups,andχ^(2)-test and binary logistic regression analysis were performed for pain index comparison.Results:There was no significant difference in terms of the efficacy of the treatment received by both groups.The mouth opening and joint pain of patients in both groups were significantly improved after treatment(P<0.001).Conclusion:Articular cavity injection of sodium hyaluronate and occlusal splint therapy are both effective and safe methods for treating ADDWoR.

Meta-Analysis of Efficacy and Safety of Mongolian Medical Warm Acupuncture in the Treatment of Lumbar Disc Herniation

Objective:To systematically evaluate the safety and efficacy of Mongolian medical warm acupuncture in the treatment of lumbar disc herniation(LDH).Methods:CNKI,Wanfang,VIP,Pubmed,Embase,Cochrane Library,and other databases were searched.The randomized controlled trials(RCTs)on the treatment of LDH with Mongolian medical warm acupuncture were manually searched in the Chinese Journal of Ethnic Medicine,Chinese Journal of Mongolian Medicine,Journal of Inner Mongolia University for Nationalities,and Journal of Inner Mongolia Medical University.The search time limit was from January 2000 to October 2023.RevMan5.4 software was used to analyze the included and excluded literature.Results:A total of 8 RCTs involving 1,042 patients with LDH were included,with 551 patients in the observation group and 491 patients in the control group.The results of the meta-analysis showed that a total of 8 randomized controlled trials were included in the treatment of LDH with Mongolian medical warm acupuncture compared with simple acupuncture(RR=1.18,95%CI=[1.12,1.23],P<0.00001).Conclusion:The total effective rate of Mongolian medical warm acupuncture for LDH is higher than that of simple acupuncture.However,due to the low quality of the literature included in this study,multi-dimensional,large sample size,and more rigorous clinical randomized trials are needed for further verification in the future.

Advances in Cervical Artificial Disc Replacement for Cervical Spondylosis

Anterior cervical decompression and fusion(ACDF)treatment for cervical spondylosis has been more than half a century,and achieved good clinical results.However,with the continuous extension of follow-up time,the fusion segment-associated postoperative complications emerged gradually.Reserved cervical stability and activity,the concept of non-fusion was born.As a non-fusion technique,cervical artificial disc replacement(CADR)developed rapidly.With the continuous development of artificial prosthesis materials and design concepts,and specification and proficiency of surgical procedures,CADR has achieved better short and mid-term clinical efficacy than ACDF.Compared with ACDF,the main advantages of CADR are that the postoperative recovery is quick,the activity and stability of cervical vertebra are maintained,the height of cervical intervertebral space is restored,and the stress of adjacent segments and the rate of surgical renovation are reduced.In clinical work,as an emerging technology,CADR requires spine surgeons to control the surgical indications,contraindications,and patients'conditions strictly.This article reviews the research progress of CADR in order to provide new ideas for clinical treatment of cervical spondylosis.

Chronic spinal cord compression associated with intervertebral disc degeneration in SPARC-null mice

Chronic spinal cord compression(CSCC)is induced by disc herniation and other reasons,leading to movement and sensation dysfunction,with a serious impact on quality of life.Spontaneous disc herniation rarely occurs in rodents,and therefore establishing a chronic spinal cord compression(CSCC)animal model is of crucial importance to explore the pathogenesis and treatment of CSCC.The absence of secreted protein,acidic,and rich in cysteine(SPARC)leads to spontaneous intervertebral disc degeneration in mice,which resembles human disc degeneration.In this study,we evaluated whether SPARC-null mice may serve as an animal model for CSCC.We performed rod rotation test,pain threshold test,gait analysis,and Basso Mouse Scale score.Our results showed that the motor function of SPARC-null mice was weakened,and magnetic resonance images revealed compression at different spinal cord levels,particularly in the lumbar segments.Immunofluorescence staining and western blot assay showed that the absence of SPARC induced apoptosis of neurons and oligodendrocytes,activation of microglia/macrophages with M1/M2 phenotype and astrocytes with A1/A2 phenotype;it also activated the expression of the NOD-like receptor protein 3 inflammasome and inhibited brain-derived neurotrophic factor/tyrosine kinase B signaling pathway.Notably,these findings are characteristics of CSCC.Therefore,we propose that SPARC-null mice may be an animal model for studying CSCC caused by disc herniation.

Endplate role in the degenerative disc disease:A brief review

The degenerative disease of the intervertebral disc is nowadays an important health problem,which has still not been understood and solved adequately.The vertebral endplate is regarded as one of the vital elements in the structure of the intervertebral disc.Its constituent cells,the chondrocytes in the endplate,may also be involved in the process of the intervertebral disc degeneration and their role is central both under physiological and pathological conditions.They main functions include a role in homeostasis of the extracellular environment of the intervertebral disc,metabolic support and nutrition of the discal nucleus and annulus beneath and the preservation of the extracellular matrix.Therefore,it is understandable that the cells in the endplate have been in the centre of research from several viewpoints,such as development,degeneration and growth,reparation and remodelling,as well as treatment strategies.In this article,we briefly review the importance of vertebral endplate,which are often overlooked,in the intervertebral disc degeneration.

Theoretical and numerical studies of rock breaking mechanism by double disc cutters

A plane mechanical model of rock breaking process by double disc cutter at the center of the cutterhead is established based on contact mechanics to analyze the stress evolution in the rock broken by cutters with different spacings. A continuous-discontinuous coupling numerical method based on zero-thickness cohesive elements is developed to simulate rock breaking using double cutters. The process, mechanism,and characteristics of rock breaking are comprehensively analyzed from five aspects: peak force, breaking form, breaking efficiency, crack mode, and breaking degree. The results show that under the penetrating action of cutters, dense cores are formed due to shear failure under respective cutters. The tensile cracks propagate in the rock, and then rock chips form with increasing penetration depth. When the cutter spacing is increased from 10 to 80 mm, the peak force gradually increases, the rock breaking range increases first and then decreases, the specific energy decreases first and then rises, and the breaking coefficient of intermediate rock decreases from 0.955 to 0.788. The area of rock breaking is positively correlated with the length of the tensile crack. Furthermore, the length of the tensile crack accounts for 14.4%–33.6% of the total crack length.