Stem cells play a crucial role in maintaining tissue regenerative capacity and homeostasis.However,mechanisms associated with stem cell senescence require further investigation.In this study,we conducted a proteomic a...Stem cells play a crucial role in maintaining tissue regenerative capacity and homeostasis.However,mechanisms associated with stem cell senescence require further investigation.In this study,we conducted a proteomic analysis of human dental pulp stem cells(HDPSCs)obtained from individuals of various ages.Our findings showed that the expression of NUP62 was decreased in aged HDPSCs.We discovered that NUP62 alleviated senescence-associated phenotypes and enhanced differentiation potential both in vitro and in vivo.Conversely,the knocking down of NUP62 expression aggravated the senescence-associated phenotypes and impaired the proliferation and migration capacity of HDPSCs.Through RNA-sequence and decoding the epigenomic landscapes remodeled induced by NUP62 overexpression,we found that NUP62 helps alleviate senescence in HDPSCs by enhancing the nuclear transport of the transcription factor E2F1.This,in turn,stimulates the transcription of the epigenetic enzyme NSD2.Finally,the overexpression of NUP62 influences the H3K36me2 and H3K36me3 modifications of anti-aging genes(HMGA1,HMGA2,and SIRT6).Our results demonstrated that NUP62 regulates the fate of HDPSCs via NSD2-dependent epigenetic reprogramming.展开更多
Pulpitis is a common infective oral disease in clinical situations.The regulatory mechanisms of immune defense in pulpitis are still being investigated.Osteomodulin(OMD)is a small leucine-rich proteoglycan family memb...Pulpitis is a common infective oral disease in clinical situations.The regulatory mechanisms of immune defense in pulpitis are still being investigated.Osteomodulin(OMD)is a small leucine-rich proteoglycan family member distributed in bones and teeth.It is a bioactive protein that promotes osteogenesis and suppresses the apoptosis of human dental pulp stem cells(hDPSCs).In this study,the role of OMD in pulpitis and the OMD-induced regulatory mechanism were investigated.The OMD expression in normal and inflamed human pulp tissues was detected via immunofluorescence staining.Intriguingly,the OMD expression decreased in the inflammatory infiltration area of pulpitis specimens.The cellular experiments demonstrated that recombined human OMD could resist the detrimental effects of lipopolysaccharide(LPS)-induced inflammation.A conditional Omd knockout mouse model with pulpal inflammation was established.LPS-induced inflammatory impairment significantly increased in conditional Omd knockout mice,whereas OMD administration exhibited a protective effect against pulpitis.Mechanistically,the transcriptome alterations of OMD overexpression showed significant enrichment in the nuclear factor-κB(NF-κB)signaling pathway.Interleukin-1 receptor 1(IL1R1),a vital membrane receptor activating the NF-κB pathway,was significantly downregulated in OMD-overexpressing hDPSCs.Additionally,the interaction between OMD and IL1R1 was verified using co-immunoprecipitation and molecular docking.In vivo,excessive pulpal inflammation in Omd-deficient mice was rescued using an IL1R antagonist.Overall,OMD played a protective role in the inflammatory response via the IL1R1/NF-κB signaling pathway.OMD may optimize the immunomodulatory functions of hDPSCs and can be used for regenerative endodontics.展开更多
Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon(RAP).Despite its therapeutic effects,the surgical risk and unclear mechanism hamper th...Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon(RAP).Despite its therapeutic effects,the surgical risk and unclear mechanism hamper the clinical application.Numerous evidences support macrophages as the key immune cells during bone remodeling.Our study discovered that the monocyte-derived macrophages primarily exhibited a pro-inflammatory phenotype that dominated bone remodeling in corticotomy by CX3CR1CreERT2;R26GFP lineage tracing system.Fluorescence staining,flow cytometry analysis,and western blot determined the significantly enhanced expression of binding immunoglobulin protein(BiP)and emphasized the activation of sensor activating transcription factor 6(ATF6)in macrophages.Then,we verified that macrophage specific ATF6 deletion(ATF6f/f;CX3CR1CreERT2 mice)decreased the proportion of pro-inflammatory macrophages and therefore blocked the acceleration effect of corticotomy.In contrast,macrophage ATF6 overexpression exaggerated the acceleration of orthodontic tooth movement.In vitro experiments also proved that higher proportion of pro-inflammatory macrophages was positively correlated with higher expression of ATF6.At the mechanism level,RNA-seq and CUT&Tag analysis demonstrated that ATF6 modulated the macrophage-orchestrated inflammation through interacting with Tnfαpromotor and augmenting its transcription.Additionally,molecular docking simulation and dual-luciferase reporter system indicated the possible binding sites outside of the traditional endoplasmic reticulum-stress response element(ERSE).Taken together,ATF6 may aggravate orthodontic bone remodeling by promoting Tnfαtranscription in macrophages,suggesting that ATF6 may represent a promising therapeutic target for non-invasive accelerated orthodontics.展开更多
Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF ...Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.展开更多
Pulpotomy,which belongs to vital pulp therapy,has become a strategy for managing pulpitis in recent decades.This minimally invasive treatment reflects the recognition of preserving healthy dental pulp and optimizing l...Pulpotomy,which belongs to vital pulp therapy,has become a strategy for managing pulpitis in recent decades.This minimally invasive treatment reflects the recognition of preserving healthy dental pulp and optimizing long-term patient-centered outcomes.Pulpotomy is categorized into partial pulpotomy(PP),the removal of a partial segment of the coronal pulp tissue,and full pulpotomy(FP),the removal of whole coronal pulp,which is followed by applying the biomaterials onto the remaining pulp tissue and ultimately restoring the tooth.Procedural decisions for the amount of pulp tissue removal or retention depend on the diagnostic of pulp vitality,the overall treatment plan,the patient’s general health status,and pulp inflammation reassessment during operation.This statement represents the consensus of an expert committee convened by the Society of Cariology and Endodontics,Chinese Stomatological Association.It addresses the current evidence to support the application of pulpotomy as a potential alternative to root canal treatment(RCT)on mature permanent teeth with pulpitis from a biological basis,the development of capping biomaterial,and the diagnostic considerations to evidence-based medicine.This expert statement intends to provide a clinical protocol of pulpotomy,which facilitates practitioners in choosing the optimal procedure and increasing their confidence in this rapidly evolving field.展开更多
Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study wa...Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study was to examine the effect of tooth loss on blood pressure among Congolese population. Methods: A cross-sectional study was conducted from October 2019 until December 2023 among Congolese population aged at least 30 years reporting to the living in DR Congo. All participants were enrolled from Dental Clinic located in the DR Congo. To be eligible to participate in the study, were the willing to participate and having signed informed consent;had a missing tooth;had carried out blood pressure measurement (hypertension/normotensive). The exclusion criteria were determined: being less than 30 years old, being pregnant for women considering the risk of existing gestational hypertension, obesity, excessive alcohol consumption, smoking, and diabetes. Hypertension was defined as the mean of three measurements of systolic blood pressure (SBP) (140 mmHg or higher), diastolic blood pressure (DBP) (90 mm or higher) or physician diagnosed hypertension confirmed from medical records. We determined the number of tooth loss from oral examination. A multivariable logistic regression model was used to investigate the effect of tooth loss on blood pressure. Results: In all, 25,396 participants were enrolled among Congolese population for this study. After oral examination, 13,421 were excluded for no tooth loss and 11,975 participants were selected. The average number of tooth loss among study population was 11.06. Among the participants with hypertension had lost an average of 11 teeth, significantly higher than those without hypertension (6.09) (p = 0.001). After adjusting for covariates (socio-demographic characteristics), tooth loss (>10) was significantly associated with hypertension, with OR = 1.32 (95% CI 1.073 - 2.38). Conclusion: Tooth loss maybe associated with severe hypertension among Congolese population adults. Prevention of tooth loss is very important to the overall health of this population.展开更多
The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing character...The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.展开更多
Tooth cracks may occur in spiral bevel gear transmission system of the aerospace equipment.In this study,an accurate and efficient loaded tooth contact analysis(LTCA)model is developed to predict the contact behavior ...Tooth cracks may occur in spiral bevel gear transmission system of the aerospace equipment.In this study,an accurate and efficient loaded tooth contact analysis(LTCA)model is developed to predict the contact behavior and time-varying meshing stiffness(TVMS)of spiral bevel gear pair with cracked tooth.The tooth is sliced,and the contact points on slices are computed using roll angle surfaces.Considering the geometric complexity of crack surface,a set of procedures is formulated to generate spatial crack and determine crack parameters for contact points.According to the positional relationship between contact point and crack path,each sliced tooth is modeled as a non-uniform cantilever beam with varying reduced effective load-bearing tooth thickness.Then the compliance model of the cracked tooth is established to perform contact analysis,along with TVMS calculations utilizing three different models.By employing spiral bevel gear pairs with distinct types of cracks as examples,the accuracy and efficiency of the developed approach are validated via comparative analyses with finite element analysis(FEA)outcomes.Furthermore,the investigation on effects of cracks shows that tooth cracks can induce alterations in meshing performance of both entire gear pair and individual tooth pairs,including not only cracked tooth pair but also adjacent non-cracked tooth pairs.Hence,the proposed model can serve as a useful tool for analyzing the variations in contact behavior and meshing stiffness of spiral bevel gears due to different cracks.展开更多
The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs(lncRNAs).However,the dynamics of lncRNA expression during human tooth development remain poorly understoo...The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs(lncRNAs).However,the dynamics of lncRNA expression during human tooth development remain poorly understood.In this research,we examined the lncRNAs present in the dental epithelium(DE)and dental mesenchyme(DM)at the late bud,cap,and early bell stages of human fetal tooth development through bulk RNA sequencing.Developmental regulators co-expressed with neighboring lncRNAs were significantly enriched in odontogenesis.Specific lncRNAs expressed in the DE and DM,such as PANCR,MIR205HG,DLX6-AS1,and DNM3OS,were identified through a combination of bulk RNA sequencing and single-cell analysis.Further subcluster analysis revealed lncRNAs specifically expressed in important regions of the tooth germ,such as the inner enamel epithelium and coronal dental papilla(CDP).Functionally,we demonstrated that CDP-specific DLX6-AS1 enhanced odontoblastic differentiation in human tooth germ mesenchymal cells and dental pulp stem cells.These findings suggest that lncRNAs could serve as valuable cell markers for tooth development and potential therapeutic targets for tooth regeneration.展开更多
Tissue interactions play a crucial role in tooth development.Notably,extracellular vesicle-mediated interactions between the mandible and tooth germ are considered essential.Here,we revealed that mandible extracellula...Tissue interactions play a crucial role in tooth development.Notably,extracellular vesicle-mediated interactions between the mandible and tooth germ are considered essential.Here,we revealed that mandible extracellular vesicles could modulate the proliferation and differentiation of dental mesenchymal cells by regulating the histone demethylase KDM2B.Further investigation showed that mandible derived extracellular vesicles could deliver miR-206 to KDM2B,thereby regulating tooth development.An animal study demonstrated that the miR-206/KDM2B pathway affected tooth morphogenesis and mineralization after eight weeks of subcutaneous transplantation in nude mice.In conclusion,this study suggested that the mandible played a critical role in tooth morphogenesis and mineralization,which could be a potential therapeutic target for abnormal tooth development and an alternative model for tooth regeneration.展开更多
Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping.This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with l...Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping.This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with less than 20%mass loss rate by bio-pulping synergistic treatment of straw fibers with deep eutectic solvent(DES)and Streptomyces rochei(S.rochei).Results illustrated that at 3%S.rochei concentration with 7-day fermentation,both cellulose and hemicellulose enzyme activities of the treated rice straw fiber reached peak values with a fiber mass loss rate of 17.01%.Microstructural morphology revealed that S.rochei colonization initiated on straw surfaces and progressively penetrated internal structures,resulting in surface loosening and distinct disruption of cell wall tissues within vascular bundles in transverse sections.The treated rice straw strip indicated a maximum tensile strength of 46.22 MPa for(Bacteria)BA 3%at day 7,attributed to optimized synergistic effects of microfibril angle(MFA)and cellulose/hemicellulose relative content ratio.The modified straw pulp film exhibited significant enhancement in the tensile index(44.9%increase),burst index(10.3%increase),and tear index(60%increase)compared to untreated groups.This work demonstrated the important role ofDES and S.rochei bio-pulping synergistic treatment in improving rice straw pulp performance,suggesting an eco-friendly,novel,and efficient biomass pretreatment technology for potential application prospects in sustainable agricultural mulching materials.展开更多
Peach are a fruit with high nutritional and economic value,but their safety and suitability for diabetic patients have been questioned.This study investigated the effects and potential mechanisms of peach pulp(PP)on t...Peach are a fruit with high nutritional and economic value,but their safety and suitability for diabetic patients have been questioned.This study investigated the effects and potential mechanisms of peach pulp(PP)on type 2 diabetes mellitus(T2DM)in mice induced by a high-fat diet(HFD)combined with streptozotocin(STZ).The results showed that PP alleviated hyperglycemia,hyperlipidemia,hyperuricemia,and tissue dysfunction in T2DM mice through the synergistic effect of nutrients and non-nutrient compounds.Analysis of mRNA expression levels revealed that PP improved glucose metabolism in T2DM mice by promoting glycogen synthesis and inhibiting gluconeogenesis.Furthermore,elevated levels of PP resulted in an increase in acetic acid content following a 4 weeks intervention period.Additionally,it led to the restoration of gut microbiota balance by decreasing the Firmicutes/Bacteroidota(F/B)ratio and enhancing the presence of Romboutsia,Allobaculum,Alloprevotella,and Bacteroides after an 8 weeks intervention.Ultimately,our results suggest that PP may offer advantages for individuals with diabetes.展开更多
Intentional tooth replantation(ITR)is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions.ITR is defined as the deliberate extraction...Intentional tooth replantation(ITR)is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions.ITR is defined as the deliberate extraction of a tooth;evaluation of the root surface,endodontic manipulation,and repair;and placement of the tooth back into its original socket.Case reports,case series,cohort studies,and randomized controlled trials have demonstrated the efficacy of ITR in the retention of natural teeth that are untreatable or difficult to manage with root canal treatment or endodontic microsurgery.However,variations in clinical protocols for ITR exist due to the empirical nature of the original protocols and rapid advancements in the field of oral biology and dental materials.This heterogeneity in protocols may cause confusion among dental practitioners;therefore,guidelines and considerations for ITR should be explicated.This expert consensus discusses the biological foundation of ITR,the available clinical protocols and current status of ITR in treating teeth with refractory apical periodontitis or anatomical aberration,and the main complications of this treatment,aiming to refine the clinical management of ITR in accordance with the progress of basic research and clinical studies;the findings suggest that ITR may become a more consistent evidence-based option in dental treatment.展开更多
Neurodegeneration involves a wide range of neuropathological alterations affecting the integrity,physiology,and architecture of neural cells.Many studies have demonstrated neurodegeneration in different animals.In the...Neurodegeneration involves a wide range of neuropathological alterations affecting the integrity,physiology,and architecture of neural cells.Many studies have demonstrated neurodegeneration in different animals.In the case of Alzheimer's disease(AD),spontaneous animal models should display two neurohistopathological hallmarks:the deposition ofβ-amyloid and the arrangement of neurofibrillary tangles.However,no natural animal models that fulfill these conditions have been reported and most research into AD has been performed using transgenic rodents.Recent studies have also demonstrated that toothed whales-homeothermic,long-lived,top predatory marine mammals-show neuropathological signs of AD-like pathology.The neuropathological hallmarks in these cetaceans could help to better understand their endangered health as well as neurodegenerative diseases in humans.This systematic review analyzes all the literature published to date on this trending topic and the proposed causes for neurodegeneration in these iconic marine mammals are approached in the context of One Health/Planetary Health and translational medicine.展开更多
BACKGROUND The two-way,three-stage psychological intervention for patients with dental pulp disease offers a reference for nursing interventions in such cases.AIM To examine the effects of a three-stage psychological ...BACKGROUND The two-way,three-stage psychological intervention for patients with dental pulp disease offers a reference for nursing interventions in such cases.AIM To examine the effects of a three-stage psychological intervention on psychological resilience and health behaviors.METHODS A total of 114 patients with dental pulp disease treated between December 2022 and December 2023 were allocated into two groups according to the random lottery method,with 57 patients in each group.The control group adopted the teaching method,while the observation group used a three-stage psychological intervention combined with the teaching method.We compared psychological resilience,coping strategies,dental fear,health behavior habits,and stigma between the two groups.RESULTS The intervention group showed significantly improved scores on the psychological resilience scale(Connor-Davidson Resilience Scale)(P<0.05);positive and negative response scores also improved after the intervention(P<0.05);significant differences were observed between the observation and control groups in the Chinese version of the Stouthard Dental Fear Scale(Dental Anxiety Inventory),the Social Impact Scale,and health behavior score(P<0.05).CONCLUSION Combining a three-stage psychological intervention with the back-teaching method effectively reduces dental fear and stigma in patients with dental pulp disease.It also improves psychological resilience,coping strategies,and health behavior habits,achieving significant results.展开更多
Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycle...Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycles.However,the effects of tooth geometry parameters could manifest as the meshing cycles increase.This study investigated the effects of tooth geometry parameters on the multi-cycle meshing temperature of polyoxymethylene(POM)worm gears,aiming to control the meshing temperature elevation by tuning the tooth geometry.Firstly,a finite element(FE)model capable of separately calculating the heat generation and simulating the heat propagation was established.Moreover,an adaptive iteration algorithm was proposed within the FE framework to capture the influence of the heat generation variation from cycle to cycle.This algorithm proved to be feasible and highly efficient compared with experimental results from the literature and simulated results via the full-iteration algorithm.Multi-cycle meshing temperature analyses were conducted on a series of POM worm gears with different tooth geometry parameters.The results reveal that,within the range of 14.5°to 25°,a pressure angle of 25°is favorable for reducing the peak surface temperature and overall body temperature of POM worm gears,which influence flank wear and load-carrying capability,respectively.However,addendum modification should be weighed because it helps with load bearing but increases the risk of severe flank wear.This paper proposes an efficient iteration algorithm for multi-cycle meshing temperature analysis of polymer gears and proves the feasibility of controlling the meshing temperature elevation during multiple cycles by tuning tooth geometry.展开更多
This study examines the development of loose-fill thermal insulation materials derived from annual plant residues,such as wheat straw,water reeds,and corn stalks,processed using the chemimechanical pulping(CMP)techniq...This study examines the development of loose-fill thermal insulation materials derived from annual plant residues,such as wheat straw,water reeds,and corn stalks,processed using the chemimechanical pulping(CMP)technique.The chopped plants were soda-cooked for 30 min,varying NaOH concentration(2%–8%on a dry basis of biomass),and mechanically refined using different disc types.The CMPprocess enhances the homogeneity and stability of defibratedmaterial,yielding improved insulation properties compared to untreated chopped rawmaterials.Chemical analysis revealed that CMP increases cellulose content and reduces lignin levels,enhancing water retention and vapor diffusion properties.Settlement tests confirmed that CMP materials are more resistant to compaction under vibration,maintaining long-term performance.Additionally,the CMP enables the production of lightweight materials that require less resource consumption while achieving comparable thermal insulation performance.The investigated biobased materials offer a sustainable alternative to conventional insulation,with competing thermal conductivity values(0.041-0.046 W/mK)at the settlement-resistant bulk density level of 60 kg/m^(3).The thermal conductivity of CMP materials remains minimally affected.However,the resulting fibers demonstrate significant advantages in stability and material efficiency.This highlights its suitability for loose-fill applications to improve the sustainability of the construction.Using renewable plant residues,CMP-based insulation materials align with circular economy principles and contribute to environmental sustainability.This research underscores the potential of CMP materials to reduce greenhouse gas emissions,optimize resource use,and promote eco-friendly building practices.展开更多
Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was...Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52%to 12.51%of the energy is utilized for rock breaking,while a significant 57.26%to 78.10%is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.展开更多
The peripheral nerve injuries,representing some of the most common types of traumatic lesions affecting the nervous system,are highly invalidating for the patients besides being a huge social burden.Although periphera...The peripheral nerve injuries,representing some of the most common types of traumatic lesions affecting the nervous system,are highly invalidating for the patients besides being a huge social burden.Although peripheral nervous system owns a higher regenerative capacity than does central nervous system,mostly depending on Schwann cells intervention in injury repair,several factors determine the extent of functional outcome after healing.Based on the injury type,different therapeutic approaches have been investigated so far.Nerve grafting and Schwann cell transplantation have represented the gold standard treatment for peripheral nerve injuries,however these approaches own limitations,such as scarce donor nerve availability and donor site morbidity.Cell based therapies might provide a suitable tool for peripheral nerve regeneration,in fact,the ability of different stem cell types to differentiate towards Schwann cells in combination with the use of different scaffolds have been widely investigated in animal models of peripheral nerve injuries in the last decade.Dental pulp is a promising cell source for regenerative medicine,because of the ease of isolation procedures,stem cell proliferation and multipotency abilities,which are due to the embryological origin from neural crest.In this article we review the literature concerning the application of tooth derived stem cell populations combined with different conduits to peripheral nerve injuries animal models,highlighting their regenerative contribution exerted through either glial differentiation and neuroprotective/neurotrophic effects on the host tissue.展开更多
The ability of human deciduous tooth dental pulp cells（HDDPCs） to differentiate into odontoblasts that generate mineralized tissue holds immense potential for therapeutic use in the field of tooth regenerative medic...The ability of human deciduous tooth dental pulp cells（HDDPCs） to differentiate into odontoblasts that generate mineralized tissue holds immense potential for therapeutic use in the field of tooth regenerative medicine. Realization of this potential depends on efficient and optimized protocols for the genetic manipulation of HDDPCs. In this study, we demonstrate the use of a Piggy Bac（PB）-based gene transfer system as a method for introducing nonviral transposon DNA into HDDPCs and HDDPC-derived inducible pluripotent stem cells. The transfection efficiency of the PB-based system was significantly greater than previously reported for electroporation-based transfection of plasmid DNA. Using the neomycin resistance gene as a selection marker, HDDPCs were stably transfected at a rate nearly 40-fold higher than that achieved using conventional methods. Using this system, it was also possible to introduce two constructs simultaneously into a single cell. The resulting stable transfectants, expressing td Tomato and enhanced green fluorescent protein, exhibited both red and green fluorescence. The established cell line did not lose the acquired phenotype over three months of culture. Based on our results, we concluded that PB is superior to currently available methods for introducing plasmid DNA into HDDPCs. There may be significant challenges in the direct clinical application of this method for human dental tissue engineering due to safety risks and ethical concerns. However, the high level of transfection achieved with PB may have significant advantages in basic scientific research for dental tissue engineering applications, such as functional studies of genes and proteins. Furthermore, it is a useful tool for the isolation of genetically engineered HDDPC-derived stem cells for studies in tooth regenerative medicine.展开更多
基金supported by the National Natural Science Foundation of China(32171347)the Foundation of Leading Talents from Shanghai Health Commission(2022XD038)+1 种基金Training Program for Research Physicians in Innovation,the Funda-mental Research Funds for the Central Universities(YG2023QNA23)Transforma-tion from shanghai hospital development center(SHDC2022CRD002).
文摘Stem cells play a crucial role in maintaining tissue regenerative capacity and homeostasis.However,mechanisms associated with stem cell senescence require further investigation.In this study,we conducted a proteomic analysis of human dental pulp stem cells(HDPSCs)obtained from individuals of various ages.Our findings showed that the expression of NUP62 was decreased in aged HDPSCs.We discovered that NUP62 alleviated senescence-associated phenotypes and enhanced differentiation potential both in vitro and in vivo.Conversely,the knocking down of NUP62 expression aggravated the senescence-associated phenotypes and impaired the proliferation and migration capacity of HDPSCs.Through RNA-sequence and decoding the epigenomic landscapes remodeled induced by NUP62 overexpression,we found that NUP62 helps alleviate senescence in HDPSCs by enhancing the nuclear transport of the transcription factor E2F1.This,in turn,stimulates the transcription of the epigenetic enzyme NSD2.Finally,the overexpression of NUP62 influences the H3K36me2 and H3K36me3 modifications of anti-aging genes(HMGA1,HMGA2,and SIRT6).Our results demonstrated that NUP62 regulates the fate of HDPSCs via NSD2-dependent epigenetic reprogramming.
基金supported by grants from the National Natural Science Foundation of China (82071104)Science and Technology Commission of Shanghai Municipality (23XD1434200/22Y21901000)+9 种基金Shanghai Hospital Development Center(SHDC12022120)National Clinical Research Center for Oral Diseases (NCRCO2021-omics-07)Shanghai Clinical Research Center for Oral Diseases (19MC1910600)Major and Key Cultivation Projects of Ninth People’s Hospital affiliated to Shanghai Jiao Tong University School of Medicine (JYZP006)Shanghai’s Top Priority Research Center (2022ZZ01017)CAMS Innovation Fund for Medical Sciences (2019-I2M-5-037)Fundamental research program funding of Ninth People’s Hospital affiliated to Shanghai Jiao Tong University School of Medicine(JYZZ237)Eastern Talent Plan Leading Project (BJZH2024001)partly supported by the Shanghai Ninth People’s Hospital affiliated with Shanghai Jiao Tong University,School of Medicine(JYJC202223)Shanghai Key Laboratory of Translational Medicine on Ear and Nose diseases (14DZ2260300)
文摘Pulpitis is a common infective oral disease in clinical situations.The regulatory mechanisms of immune defense in pulpitis are still being investigated.Osteomodulin(OMD)is a small leucine-rich proteoglycan family member distributed in bones and teeth.It is a bioactive protein that promotes osteogenesis and suppresses the apoptosis of human dental pulp stem cells(hDPSCs).In this study,the role of OMD in pulpitis and the OMD-induced regulatory mechanism were investigated.The OMD expression in normal and inflamed human pulp tissues was detected via immunofluorescence staining.Intriguingly,the OMD expression decreased in the inflammatory infiltration area of pulpitis specimens.The cellular experiments demonstrated that recombined human OMD could resist the detrimental effects of lipopolysaccharide(LPS)-induced inflammation.A conditional Omd knockout mouse model with pulpal inflammation was established.LPS-induced inflammatory impairment significantly increased in conditional Omd knockout mice,whereas OMD administration exhibited a protective effect against pulpitis.Mechanistically,the transcriptome alterations of OMD overexpression showed significant enrichment in the nuclear factor-κB(NF-κB)signaling pathway.Interleukin-1 receptor 1(IL1R1),a vital membrane receptor activating the NF-κB pathway,was significantly downregulated in OMD-overexpressing hDPSCs.Additionally,the interaction between OMD and IL1R1 was verified using co-immunoprecipitation and molecular docking.In vivo,excessive pulpal inflammation in Omd-deficient mice was rescued using an IL1R antagonist.Overall,OMD played a protective role in the inflammatory response via the IL1R1/NF-κB signaling pathway.OMD may optimize the immunomodulatory functions of hDPSCs and can be used for regenerative endodontics.
基金supported by the National Natural Science Foundation of China(82071143,82371000,82270361)Key Research and Development Program of Jiangsu Province(BE2022795)+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_1801)the Jiangsu Province Capability Improvement Project through the Science,Technology and Education-Jiangsu Provincial Research Hospital Cultivation Unit(YJXYYJSDW4)Jiangsu Provincial Medical Innovation Center(CXZX202227).
文摘Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon(RAP).Despite its therapeutic effects,the surgical risk and unclear mechanism hamper the clinical application.Numerous evidences support macrophages as the key immune cells during bone remodeling.Our study discovered that the monocyte-derived macrophages primarily exhibited a pro-inflammatory phenotype that dominated bone remodeling in corticotomy by CX3CR1CreERT2;R26GFP lineage tracing system.Fluorescence staining,flow cytometry analysis,and western blot determined the significantly enhanced expression of binding immunoglobulin protein(BiP)and emphasized the activation of sensor activating transcription factor 6(ATF6)in macrophages.Then,we verified that macrophage specific ATF6 deletion(ATF6f/f;CX3CR1CreERT2 mice)decreased the proportion of pro-inflammatory macrophages and therefore blocked the acceleration effect of corticotomy.In contrast,macrophage ATF6 overexpression exaggerated the acceleration of orthodontic tooth movement.In vitro experiments also proved that higher proportion of pro-inflammatory macrophages was positively correlated with higher expression of ATF6.At the mechanism level,RNA-seq and CUT&Tag analysis demonstrated that ATF6 modulated the macrophage-orchestrated inflammation through interacting with Tnfαpromotor and augmenting its transcription.Additionally,molecular docking simulation and dual-luciferase reporter system indicated the possible binding sites outside of the traditional endoplasmic reticulum-stress response element(ERSE).Taken together,ATF6 may aggravate orthodontic bone remodeling by promoting Tnfαtranscription in macrophages,suggesting that ATF6 may represent a promising therapeutic target for non-invasive accelerated orthodontics.
基金the National Science and Technology Major Project of China(No.2019-VII0017e0158)the National Natural Science Foundation of China(No.U21A20131)+1 种基金the Industry-University Research Cooperation Project,China(No.HFZL2020CXY025)the National Key Laboratory of Science and Technology on Helicopter Transmission,China(No.HTL-O-21G05).
文摘Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.
基金supported by the National Natural Science Foundation of China(82170941 and 82370948 to Lu Zhang,82071110 and 82230029 to Zhi Chen)the National Key R&D Program of China(2018YFC1105100)。
文摘Pulpotomy,which belongs to vital pulp therapy,has become a strategy for managing pulpitis in recent decades.This minimally invasive treatment reflects the recognition of preserving healthy dental pulp and optimizing long-term patient-centered outcomes.Pulpotomy is categorized into partial pulpotomy(PP),the removal of a partial segment of the coronal pulp tissue,and full pulpotomy(FP),the removal of whole coronal pulp,which is followed by applying the biomaterials onto the remaining pulp tissue and ultimately restoring the tooth.Procedural decisions for the amount of pulp tissue removal or retention depend on the diagnostic of pulp vitality,the overall treatment plan,the patient’s general health status,and pulp inflammation reassessment during operation.This statement represents the consensus of an expert committee convened by the Society of Cariology and Endodontics,Chinese Stomatological Association.It addresses the current evidence to support the application of pulpotomy as a potential alternative to root canal treatment(RCT)on mature permanent teeth with pulpitis from a biological basis,the development of capping biomaterial,and the diagnostic considerations to evidence-based medicine.This expert statement intends to provide a clinical protocol of pulpotomy,which facilitates practitioners in choosing the optimal procedure and increasing their confidence in this rapidly evolving field.
文摘Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study was to examine the effect of tooth loss on blood pressure among Congolese population. Methods: A cross-sectional study was conducted from October 2019 until December 2023 among Congolese population aged at least 30 years reporting to the living in DR Congo. All participants were enrolled from Dental Clinic located in the DR Congo. To be eligible to participate in the study, were the willing to participate and having signed informed consent;had a missing tooth;had carried out blood pressure measurement (hypertension/normotensive). The exclusion criteria were determined: being less than 30 years old, being pregnant for women considering the risk of existing gestational hypertension, obesity, excessive alcohol consumption, smoking, and diabetes. Hypertension was defined as the mean of three measurements of systolic blood pressure (SBP) (140 mmHg or higher), diastolic blood pressure (DBP) (90 mm or higher) or physician diagnosed hypertension confirmed from medical records. We determined the number of tooth loss from oral examination. A multivariable logistic regression model was used to investigate the effect of tooth loss on blood pressure. Results: In all, 25,396 participants were enrolled among Congolese population for this study. After oral examination, 13,421 were excluded for no tooth loss and 11,975 participants were selected. The average number of tooth loss among study population was 11.06. Among the participants with hypertension had lost an average of 11 teeth, significantly higher than those without hypertension (6.09) (p = 0.001). After adjusting for covariates (socio-demographic characteristics), tooth loss (>10) was significantly associated with hypertension, with OR = 1.32 (95% CI 1.073 - 2.38). Conclusion: Tooth loss maybe associated with severe hypertension among Congolese population adults. Prevention of tooth loss is very important to the overall health of this population.
基金Project(2024A1515240020)supported by the Guangdong Basic and Applied Basic Research Foundation,China。
文摘The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.
基金co-supported by the National Natural Science Foundation of China (No. 52175104)the Postdoctoral Fellowship Program of CPSF (No. GZC20233008)
文摘Tooth cracks may occur in spiral bevel gear transmission system of the aerospace equipment.In this study,an accurate and efficient loaded tooth contact analysis(LTCA)model is developed to predict the contact behavior and time-varying meshing stiffness(TVMS)of spiral bevel gear pair with cracked tooth.The tooth is sliced,and the contact points on slices are computed using roll angle surfaces.Considering the geometric complexity of crack surface,a set of procedures is formulated to generate spatial crack and determine crack parameters for contact points.According to the positional relationship between contact point and crack path,each sliced tooth is modeled as a non-uniform cantilever beam with varying reduced effective load-bearing tooth thickness.Then the compliance model of the cracked tooth is established to perform contact analysis,along with TVMS calculations utilizing three different models.By employing spiral bevel gear pairs with distinct types of cracks as examples,the accuracy and efficiency of the developed approach are validated via comparative analyses with finite element analysis(FEA)outcomes.Furthermore,the investigation on effects of cracks shows that tooth cracks can induce alterations in meshing performance of both entire gear pair and individual tooth pairs,including not only cracked tooth pair but also adjacent non-cracked tooth pairs.Hence,the proposed model can serve as a useful tool for analyzing the variations in contact behavior and meshing stiffness of spiral bevel gears due to different cracks.
基金supported by the National Key Research and Development Program(2022YFA1104401)Beijing Municipal Government grant(Beijing Laboratory of Oral Health,PXM2021-014226-000041)+3 种基金Beijing Municipal Govemment(Beijing Scholar Program,PXM2021-014226-000020)National Natural Science Foundation of China(82030031,92149301,81991504,L2224038,82270945)Innovation Research Team Project of Beijing Stomatological Hospital,Capital Medical University(CXTD202201)Chinese Research Unit of Tooth Development and Regeneration,Academy of Medical Sciences(2019-12M-5-031).
文摘The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs(lncRNAs).However,the dynamics of lncRNA expression during human tooth development remain poorly understood.In this research,we examined the lncRNAs present in the dental epithelium(DE)and dental mesenchyme(DM)at the late bud,cap,and early bell stages of human fetal tooth development through bulk RNA sequencing.Developmental regulators co-expressed with neighboring lncRNAs were significantly enriched in odontogenesis.Specific lncRNAs expressed in the DE and DM,such as PANCR,MIR205HG,DLX6-AS1,and DNM3OS,were identified through a combination of bulk RNA sequencing and single-cell analysis.Further subcluster analysis revealed lncRNAs specifically expressed in important regions of the tooth germ,such as the inner enamel epithelium and coronal dental papilla(CDP).Functionally,we demonstrated that CDP-specific DLX6-AS1 enhanced odontoblastic differentiation in human tooth germ mesenchymal cells and dental pulp stem cells.These findings suggest that lncRNAs could serve as valuable cell markers for tooth development and potential therapeutic targets for tooth regeneration.
基金supported by the National Natural Science Foundation of China(No.82071078,82370939)the Shaanxi Provincial High-level Talent Program and Young Talent Support Plan of Xi’an Jiaotong University.
文摘Tissue interactions play a crucial role in tooth development.Notably,extracellular vesicle-mediated interactions between the mandible and tooth germ are considered essential.Here,we revealed that mandible extracellular vesicles could modulate the proliferation and differentiation of dental mesenchymal cells by regulating the histone demethylase KDM2B.Further investigation showed that mandible derived extracellular vesicles could deliver miR-206 to KDM2B,thereby regulating tooth development.An animal study demonstrated that the miR-206/KDM2B pathway affected tooth morphogenesis and mineralization after eight weeks of subcutaneous transplantation in nude mice.In conclusion,this study suggested that the mandible played a critical role in tooth morphogenesis and mineralization,which could be a potential therapeutic target for abnormal tooth development and an alternative model for tooth regeneration.
基金funded by the Agricultural Science and Technology Innovation Fund of Jiangsu Province[Grant/Award Number:CX(24)1008]Key Research and Development Program Project of Henan Province(251111110100)National State Science Foundation of China[Grant/Award Number:21808093].
文摘Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping.This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with less than 20%mass loss rate by bio-pulping synergistic treatment of straw fibers with deep eutectic solvent(DES)and Streptomyces rochei(S.rochei).Results illustrated that at 3%S.rochei concentration with 7-day fermentation,both cellulose and hemicellulose enzyme activities of the treated rice straw fiber reached peak values with a fiber mass loss rate of 17.01%.Microstructural morphology revealed that S.rochei colonization initiated on straw surfaces and progressively penetrated internal structures,resulting in surface loosening and distinct disruption of cell wall tissues within vascular bundles in transverse sections.The treated rice straw strip indicated a maximum tensile strength of 46.22 MPa for(Bacteria)BA 3%at day 7,attributed to optimized synergistic effects of microfibril angle(MFA)and cellulose/hemicellulose relative content ratio.The modified straw pulp film exhibited significant enhancement in the tensile index(44.9%increase),burst index(10.3%increase),and tear index(60%increase)compared to untreated groups.This work demonstrated the important role ofDES and S.rochei bio-pulping synergistic treatment in improving rice straw pulp performance,suggesting an eco-friendly,novel,and efficient biomass pretreatment technology for potential application prospects in sustainable agricultural mulching materials.
基金supported by the Zhejiang Key R&D Program of China(2020C02037)the Ningbo Agricultural Research Program of China(2022S1542022S138).
文摘Peach are a fruit with high nutritional and economic value,but their safety and suitability for diabetic patients have been questioned.This study investigated the effects and potential mechanisms of peach pulp(PP)on type 2 diabetes mellitus(T2DM)in mice induced by a high-fat diet(HFD)combined with streptozotocin(STZ).The results showed that PP alleviated hyperglycemia,hyperlipidemia,hyperuricemia,and tissue dysfunction in T2DM mice through the synergistic effect of nutrients and non-nutrient compounds.Analysis of mRNA expression levels revealed that PP improved glucose metabolism in T2DM mice by promoting glycogen synthesis and inhibiting gluconeogenesis.Furthermore,elevated levels of PP resulted in an increase in acetic acid content following a 4 weeks intervention period.Additionally,it led to the restoration of gut microbiota balance by decreasing the Firmicutes/Bacteroidota(F/B)ratio and enhancing the presence of Romboutsia,Allobaculum,Alloprevotella,and Bacteroides after an 8 weeks intervention.Ultimately,our results suggest that PP may offer advantages for individuals with diabetes.
文摘Intentional tooth replantation(ITR)is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions.ITR is defined as the deliberate extraction of a tooth;evaluation of the root surface,endodontic manipulation,and repair;and placement of the tooth back into its original socket.Case reports,case series,cohort studies,and randomized controlled trials have demonstrated the efficacy of ITR in the retention of natural teeth that are untreatable or difficult to manage with root canal treatment or endodontic microsurgery.However,variations in clinical protocols for ITR exist due to the empirical nature of the original protocols and rapid advancements in the field of oral biology and dental materials.This heterogeneity in protocols may cause confusion among dental practitioners;therefore,guidelines and considerations for ITR should be explicated.This expert consensus discusses the biological foundation of ITR,the available clinical protocols and current status of ITR in treating teeth with refractory apical periodontitis or anatomical aberration,and the main complications of this treatment,aiming to refine the clinical management of ITR in accordance with the progress of basic research and clinical studies;the findings suggest that ITR may become a more consistent evidence-based option in dental treatment.
文摘Neurodegeneration involves a wide range of neuropathological alterations affecting the integrity,physiology,and architecture of neural cells.Many studies have demonstrated neurodegeneration in different animals.In the case of Alzheimer's disease(AD),spontaneous animal models should display two neurohistopathological hallmarks:the deposition ofβ-amyloid and the arrangement of neurofibrillary tangles.However,no natural animal models that fulfill these conditions have been reported and most research into AD has been performed using transgenic rodents.Recent studies have also demonstrated that toothed whales-homeothermic,long-lived,top predatory marine mammals-show neuropathological signs of AD-like pathology.The neuropathological hallmarks in these cetaceans could help to better understand their endangered health as well as neurodegenerative diseases in humans.This systematic review analyzes all the literature published to date on this trending topic and the proposed causes for neurodegeneration in these iconic marine mammals are approached in the context of One Health/Planetary Health and translational medicine.
基金ORCID number:Qing-Feng Wang 0009-0009-4579-7133Ying Wu 0009-0007-2061-739X。
文摘BACKGROUND The two-way,three-stage psychological intervention for patients with dental pulp disease offers a reference for nursing interventions in such cases.AIM To examine the effects of a three-stage psychological intervention on psychological resilience and health behaviors.METHODS A total of 114 patients with dental pulp disease treated between December 2022 and December 2023 were allocated into two groups according to the random lottery method,with 57 patients in each group.The control group adopted the teaching method,while the observation group used a three-stage psychological intervention combined with the teaching method.We compared psychological resilience,coping strategies,dental fear,health behavior habits,and stigma between the two groups.RESULTS The intervention group showed significantly improved scores on the psychological resilience scale(Connor-Davidson Resilience Scale)(P<0.05);positive and negative response scores also improved after the intervention(P<0.05);significant differences were observed between the observation and control groups in the Chinese version of the Stouthard Dental Fear Scale(Dental Anxiety Inventory),the Social Impact Scale,and health behavior score(P<0.05).CONCLUSION Combining a three-stage psychological intervention with the back-teaching method effectively reduces dental fear and stigma in patients with dental pulp disease.It also improves psychological resilience,coping strategies,and health behavior habits,achieving significant results.
基金Supported by National Key R&D Program of China(Grant No.2019YFE0121300)。
文摘Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycles.However,the effects of tooth geometry parameters could manifest as the meshing cycles increase.This study investigated the effects of tooth geometry parameters on the multi-cycle meshing temperature of polyoxymethylene(POM)worm gears,aiming to control the meshing temperature elevation by tuning the tooth geometry.Firstly,a finite element(FE)model capable of separately calculating the heat generation and simulating the heat propagation was established.Moreover,an adaptive iteration algorithm was proposed within the FE framework to capture the influence of the heat generation variation from cycle to cycle.This algorithm proved to be feasible and highly efficient compared with experimental results from the literature and simulated results via the full-iteration algorithm.Multi-cycle meshing temperature analyses were conducted on a series of POM worm gears with different tooth geometry parameters.The results reveal that,within the range of 14.5°to 25°,a pressure angle of 25°is favorable for reducing the peak surface temperature and overall body temperature of POM worm gears,which influence flank wear and load-carrying capability,respectively.However,addendum modification should be weighed because it helps with load bearing but increases the risk of severe flank wear.This paper proposes an efficient iteration algorithm for multi-cycle meshing temperature analysis of polymer gears and proves the feasibility of controlling the meshing temperature elevation during multiple cycles by tuning tooth geometry.
基金funded by the LatvianCouncil of Science,the project“Investigation of Eco-Friendly Thermal Insulation Materials from Sustainable and Renewable Industrial Crops Residuals,”number lzp-2021/1-0599.
文摘This study examines the development of loose-fill thermal insulation materials derived from annual plant residues,such as wheat straw,water reeds,and corn stalks,processed using the chemimechanical pulping(CMP)technique.The chopped plants were soda-cooked for 30 min,varying NaOH concentration(2%–8%on a dry basis of biomass),and mechanically refined using different disc types.The CMPprocess enhances the homogeneity and stability of defibratedmaterial,yielding improved insulation properties compared to untreated chopped rawmaterials.Chemical analysis revealed that CMP increases cellulose content and reduces lignin levels,enhancing water retention and vapor diffusion properties.Settlement tests confirmed that CMP materials are more resistant to compaction under vibration,maintaining long-term performance.Additionally,the CMP enables the production of lightweight materials that require less resource consumption while achieving comparable thermal insulation performance.The investigated biobased materials offer a sustainable alternative to conventional insulation,with competing thermal conductivity values(0.041-0.046 W/mK)at the settlement-resistant bulk density level of 60 kg/m^(3).The thermal conductivity of CMP materials remains minimally affected.However,the resulting fibers demonstrate significant advantages in stability and material efficiency.This highlights its suitability for loose-fill applications to improve the sustainability of the construction.Using renewable plant residues,CMP-based insulation materials align with circular economy principles and contribute to environmental sustainability.This research underscores the potential of CMP materials to reduce greenhouse gas emissions,optimize resource use,and promote eco-friendly building practices.
基金Supported by Major Instrument Project of National Natural Science Foundation of China(52327803)Major Project of National Natural Science Foundation of China(52192622).
文摘Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52%to 12.51%of the energy is utilized for rock breaking,while a significant 57.26%to 78.10%is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.
文摘The peripheral nerve injuries,representing some of the most common types of traumatic lesions affecting the nervous system,are highly invalidating for the patients besides being a huge social burden.Although peripheral nervous system owns a higher regenerative capacity than does central nervous system,mostly depending on Schwann cells intervention in injury repair,several factors determine the extent of functional outcome after healing.Based on the injury type,different therapeutic approaches have been investigated so far.Nerve grafting and Schwann cell transplantation have represented the gold standard treatment for peripheral nerve injuries,however these approaches own limitations,such as scarce donor nerve availability and donor site morbidity.Cell based therapies might provide a suitable tool for peripheral nerve regeneration,in fact,the ability of different stem cell types to differentiate towards Schwann cells in combination with the use of different scaffolds have been widely investigated in animal models of peripheral nerve injuries in the last decade.Dental pulp is a promising cell source for regenerative medicine,because of the ease of isolation procedures,stem cell proliferation and multipotency abilities,which are due to the embryological origin from neural crest.In this article we review the literature concerning the application of tooth derived stem cell populations combined with different conduits to peripheral nerve injuries animal models,highlighting their regenerative contribution exerted through either glial differentiation and neuroprotective/neurotrophic effects on the host tissue.
基金supported in part by a Grant-in-Aid for Scientific Research (C) (grant no. 25463192) from the Ministry of Education, Science, Sports, Culture, and Technology of Japan
文摘The ability of human deciduous tooth dental pulp cells（HDDPCs） to differentiate into odontoblasts that generate mineralized tissue holds immense potential for therapeutic use in the field of tooth regenerative medicine. Realization of this potential depends on efficient and optimized protocols for the genetic manipulation of HDDPCs. In this study, we demonstrate the use of a Piggy Bac（PB）-based gene transfer system as a method for introducing nonviral transposon DNA into HDDPCs and HDDPC-derived inducible pluripotent stem cells. The transfection efficiency of the PB-based system was significantly greater than previously reported for electroporation-based transfection of plasmid DNA. Using the neomycin resistance gene as a selection marker, HDDPCs were stably transfected at a rate nearly 40-fold higher than that achieved using conventional methods. Using this system, it was also possible to introduce two constructs simultaneously into a single cell. The resulting stable transfectants, expressing td Tomato and enhanced green fluorescent protein, exhibited both red and green fluorescence. The established cell line did not lose the acquired phenotype over three months of culture. Based on our results, we concluded that PB is superior to currently available methods for introducing plasmid DNA into HDDPCs. There may be significant challenges in the direct clinical application of this method for human dental tissue engineering due to safety risks and ethical concerns. However, the high level of transfection achieved with PB may have significant advantages in basic scientific research for dental tissue engineering applications, such as functional studies of genes and proteins. Furthermore, it is a useful tool for the isolation of genetically engineered HDDPC-derived stem cells for studies in tooth regenerative medicine.
