Search

Caries is a chronic infectious disease that occurs in the hard tissues of teeth. The interaction of oral microorganisms, host, food and time leads to the occurrence and progression of caries. Free sugar is an important food factor in the occurrence of dental caries. This paper reviews the research progress on the relationship between free sugar and caries in recent years, providing a reference for further clarifying the mechanism of the occurrence and progression of caries caused by free sugar and exploring the methods of caries prevention. The cariogenic mechanism of free sugar is multifaceted. Free sugar can not only be used by oral microorganisms in dental plaque biofilms to produce acid and synthesize intracellular and extracellular polysaccharides but also cause an imbalance in oral microecology and enhance gene expression related to the cariogenic toxicity of oral microorganisms. Based on the correlation between free sugar and caries, it is important to limit the intake amount and frequency of free sugar to prevent caries. This can be achieved mainly by formulating public health policies for reducing sugar, creating a low-sugar family environment with good eating habits, using sugar substitutes and using fluoride. There are few studies on the relationship between free sugar and oral microecology. More research is needed to better understand the effect of free sugar on oral microecology and its mechanism and to validate the caries-preventing effect of various sugar reduction measures. We believe such studies would open up new avenues for the effective prevention of caries.

Periodontitis is a multifactorial infectious and inflammatory disease occurring in tooth-supporting tissues. In recent decades, many studies have reported a potential relationship between periodontitis and cardiovascular disease, and periodontal pathogens are an important factor linking periodontitis and cardiovascular disease. In this review, we summarize updated preclinical studies and epidemiological evidence on the association of these two diseases. Moreover, possible mechanisms accounting for such links are introduced, including bacteremia and direct invasion of pathogens, endotoxemia caused by virulence factors of periodontal pathogens leading to systemic inflammation, abnormal lipid metabolism and oxidative stress, which further affect the inflammatory states of the cardiovascular system. The molecular mimicry theory and the intrinsic correlation of apolipoprotein E between periodontitis and cardiovascular disease require further study. Combined with existing studies, it is reasonable to assume that periodontal treatment and oral hygiene can reduce the risk of cardiovascular disease in patients with periodontitis. More studies are needed to focus on the molecular mechanism linking periodontal pathogens and cardiovascular diseases. These studies will provide evidence that periodontal pathogens directly invade the cardiovascular system or indirectly invade host cells as well as isolate and culture bacteria from the tissues of lesions. Studies should also explore how the local inflammatory state, periodontal pathogens and their products directly influence cardiovascular disease-related biomarkers (C-reactive protein, vascular endothelial growth factor, heat shock protein, etc.) and the mechanism. This information may provide a reference for the effective prevention and treatment of periodontitis and cardiovascular disease in the future.

Salivary exosomes are extracellular vesicles with a diameter of 30-50 nm in saliva. With the development of technology in recent years, many studies have revealed that salivary exosomes play an important role in the occurrence and development of various oral diseases. For example, salivary exosomal CD9 and CD81 promote tumor cell metastasis by regulating the cell adhesion and movement, salivary exosomal miR-24-3p promotes the tumor cell proliferation by acting on PER1, and salivary exosomal programmed cell death-ligand 1 (PD-L1) mRNA inhibits the destruction of inflammatory tissue, which can be biomarkers for the diagnosis of oral cancer, periodontitis and other oral diseases. Therefore, salivary exosomes can be used as potential prognostic and diagnostic markers for oral diseases. In addition to oral diseases, such as oral cancer, periodontitis, oral lichen planus, Sjogren’s syndrome, etc., salivary exosomes are closely related to distant tumors, such as pancreatic cancer, lung cancer, and systemic diseases, such as Parkinson’s disease, inflammatory bowel disease, etc. It is of great significance to study the role of salivary exosomes in the diagnosis and treatment of oral and systemic diseases and to develop the potential of salivary exosomes as biomarkers for disease diagnosis.

Treponema denticola is an important pathogenic Treponema pathogen in the human oral cavity. Early studies have found that Treponema denticola is closely related to the occurrence and development of periodontal diseases. With the development of technical methods in recent years, many studies have shown that Treponema denticola not only can participate in periodontal diseases through a variety of mechanisms but also can play an important role in the development of various oral diseases. Treponema denticola is detected in high concentrations in peri-apical diseases and peri-implant diseases, and its surface protein is also prevalent in oral tumor samples. This paper reviews the research progress of Treponema denticola in periodontal diseases, pulp peri-apical diseases, peri-implant diseases and oral tumors, and summarizes the relevant mechanisms. For example, Treponema denticola can cause immune regulation disorder, destroy the epithelial barrier, induce bone absorption, promote the occurrence and development of inflammation through a variety of surface proteins, including chymotrypsin-like protease complex (CTLP), major outer sheath protein (Mosp), Td92, and LOS. It can also escape complement-mediated killing effects through surface FhbB lipoproteins and promote the occurrence and development of oral tumors by regulating the tumor microenvironment. These theories provide a theoretical basis for further understanding the development of oral diseases, controlling the infection of Treponema denticola, and exploring more effective treatment strategies.

Microorganisms are closely related to the occurrence and development of common oral diseases. Due to the unique physiological and anatomical characteristics of the oral cavity, locally introduced antibacterial drugs cannot be maintained in the effective concentration range under the effect of saliva erosion. Therefore, to enhance the retention and bioavailability of antibacterial drugs in biofilms, some scholars designed pH sensitive drug delivery systems with the fact that the pH value of oral biofilm is lower than the physiological pH value. This article reviews the research reports of a pH-sensitive drug delivery system in the oral cavity and elaborates its application in oral diseases such as dental caries, endodontic disease, periapical disease, peri-implant diseases, and oral candidiasis. Literature review Results show that the pH-sensitive drug delivery system loaded with antibacterial drugs could be used for the control of oral microorganisms with excellent pH sensitivity and antibacterial properties, especially in the application of acid-producing bacteria such as Streptococcus mutans for the prevention and treatment of dental caries. However, the research of pH-sensitive drug delivery systems in the oral cavity is still limited to basic research,and in clinical applications, it still faces many challenges, such as a complex design and synthesis, difficulties with lasting effects and eliminating drug-resistance and persistent bacteria. Further optimization of pH sensitive systems, as well as animal experiments and in vivo studies will be the focus of future research.

Reducing the adhesion of microorganisms and the formation of biofilms on implant surfaces can prevent peri-implant inflammation and optimize the long-term prognosis of implanted dentures. To provide theoretical support for the development of new materials or the modification of existing materials and the improvement of the success rate of implant repair, a literature review was conducted, which shows that the factors influencing bacterial adhesion on dental implant surfaces included the type of implant material, material roughness, nonspecific physical and chemical properties, the type of antibacterial coating, the components of the acquired membrane on the implant surface, the structure of the bacterial cell wall, etc. The current research direction of implant materials aims to reduce bacterial adhesion and promote bone bonding. However, there is no consensus on the physical and chemical properties of implants that meet this requirement. At present, the development trend in implant materials is guided by research of the “core microbiome” of peri-implant inflammation, based on study of the factors related to the adhesion of pathogenic microorganisms to the implant surface, which is organically combined with a variety of modification methods to change the surface-related properties of the implant materials and even to endow the implant with antibacterial properties to reduce or inhibit the adhesion of pathogenic bacteria to the implant.

Replacing the hydraulic oil in hydraulic motors with the natural water will lead to an increase in the leakage of the wheel train and a decrease in the volumetric efficiency of motors. In order to improve the volumetric efficiency of the non-circular planetary gear hydraulic motors, the influence of axial clearance between the wheel train and the distribution plate on the volumetric efficiency of the motor is quantitatively analyzed. Firstly, according to the principle of the gap leakage in the rotating plane and the friction force in the fluid, the leakage and power loss formula between the wheels were derived, so as to calculate the optimal solution of the axial clearance of the motor under 30 MPa pressure difference. Secondly, on the basis of considering the manufacturing error, based on the dynamic grid and user-defined function (UDF) programming technology, the leakage amount and volumetric efficiency of the motor under different axial clearances were detected and analyzed, and the theoretical volumetric efficiency of the motor under the same conditions was calculated. The two were compared to obtain the change trend and the minimum value of motor volumetric efficiency under different working conditions. The results show that from the calculation results of selecting the axial clearance value, when the flatness of the wheel is 0.01 mm, the volumetric efficiency of the motor is not less than 77.28% within the working pressure difference of 30 MPa. It provides a basis for the structural improvement of subsequent motors.

Overhead ground wire (OGW) is an important equipment to prevent transmission wire from being struck by lightning. When OGW is struck by lightning, the sliding motion of arc root causes different damage mechanism. Therefore, it is necessary to analyze the sliding motion of arc root first, so as to provide data support of sliding displacement for the research of damage mechanism. In this paper, the sliding motion model of arc root along OGW is established based on the arc chain modeling method. By analyzing the main influence range of the electromagnetic force, the space boundary of modeling is narrowed, so the calculation amount is greatly reduced. Then, the model is verified by the needle-wire discharge experiment in the laboratory. Finally, based on the established model, the factors affecting the sliding displacement of arc root are analyzed, including thermal buoyancy, return stroke and continuous current. The results show that the effect of thermal buoyancy can be ignored under the action of return stroke. The sliding displacement of arc root is positively correlated with the wavelength time, but not with the wave head time. However, under the action of continuous current, thermal buoyancy affects the evaluation result of arc root sliding displacement, and the maximum error is more than 25%.

Piezoelectric materials， as important functional materials， have been widely used in various fields of the national economy for the preparation of structural health detection devices. With the development of modern industrial technology， especially aerospace， nuclear energy， and intelligent manufacturing， various high-temperature conditions have put forward higher requirements for the performance of piezoelectric materials. Therefore， the development of high-temperature piezoelectric materials with excellent comprehensive performance and their application in sensor devices with higher service temperatures have received widespread attention from researchers. Fresnoite （Ba2TiSi2O8， BTS） crystal is a kind of promising piezoelectric material for high-temperature sensing applications due to its high electrical resistivity， low dielectric loss， and excellent piezoelectric properties. The preparation process of BTS crystal by Czochralski method， characterization of single crystal electro-elastic properties， phase transition regulation， and the research progress of surface acoustic wave sensors and high-temperature vibration sensors based on BTS piezoelectric crystal were introduced in this paper. Finally， the research and development of new high-temperature piezoelectric crystals and their sensors were summarized and presented.

In order to solve the problems of limited slip limiting ability, complex configuration and difficult manufacturing of inter-axle limited slip differentials, a new design scheme of inter-axle limited slip differentials with face gears is proposed. By analyzing the configuration principle and motion characteristics of the differential, the mechanical balance equation and locking coefficient theoretical model of the differential are established. Based on the machining principle of face gears and the working characteristics of differentials, the 3D entity model and Adams virtual prototype are built. The multi-body dynamics is analyzed by Adams simulation software. The results show that the locking ratio of differentials to the front and rear axles can reach 6.5 and 5. When travelling on a good road, the output torque of the front and rear axles is basically consistent with the preset torque distribution ratio of 40∶60. When travelling on the double-adhesion-coefficient road surface, the slipping axle can be locked quickly, more torque can be distributed to the non-slipping axle, and the torque distribution to the front and rear axles can reach 73% and 79% respectively. The results verify the feasibility of the inter-axle limited slip differential with face gears, and provide a basis for its design and application.

In order to improve the machining accuracy of the orthogonal spur face gear, this study proposes a precise design method of a skiving tool for the orthogonal spur face gear. Based on the meshing principle of the gear cross axis, the skiving process of the face gear is analyzed. By the involute tooth profile of the cylindrical gear meshing with the face gear, the equation of the skiving tool tooth surface is enveloped. Based on the normal section, the error-free skiving tool structure is designed and the expression of the cutters' cutting edge is deduced. Solve the meshing condition of the cutting edge and the face gear, deduce the numerical control machining law, and carry out theoretical calculation and simulation machining of the face gear's tooth surface. The numerical comparison between the skiving tooth surface and the theoretical tooth surface of the face gear shows that, the theoretical tooth surface of the face gear can be obtained when the skiving tool has no error. In the Vericut simulation, the tooth surface error can be kept within 10 μm.

It is expected that fusion energy development, which is at a critical stage of breaking through energy break-even in the engineering sense, has the potential to reshape the future pattern of energy development with both opportunities and challenges. This study reviews the main progress of fusion energy research and summarizes the major challenges regarding energy balance, tritium selfsustainability, high availability, development of irradiation-resistant materials, and economical efficiency in general sense. On the basis of sorting out the common basic technology breakthroughs of the International Thermonuclear Experimental Reactor (ITER) program and the supporting research activities of its member states, the study summarizes the progress of China’s magnetic confinement fusion research in terms of overall planning, self-developed projects, and technical tracking. Furthermore, focusing on the Z-pinch-driven fusion-fission hybrid reactor (Z-FFR) concept, which is independently proposed by China, this study elaborates on the basic principles, application advantages, and series of progresses, and proposes a development plan toward commercial energy supply by 2040, covering the task objectives in the stages of key technology campaign, engineering demonstration, and promotion of commercial power generation. To comprehensively promote China’s fusion energy development, several suggestions are given. In the magnetic confinement fusion area, it is suggest that China deeply participate in the ITER program and relevant international cooperation, overcome key physics and engineering technologies of commercial fusion reactors, promote the research and development of key components of China Fusion Engineering Test Reactor (CFETR) device, and construct and operate CFETR in due course. In the Z-FFR area, it is of first priority to start the construction of electromagnetic-driven large-scale scientific devices the soonest possible, develop key technologies for fusion energy, and promote both engineering demonstrations and commercial projects in proper time.

With the rapid development of society, cardiac arrest has become a major public health problem worldwide. For cardiac arrest patients, the primary goal of cardiopulmonary resuscitation(CPR) is to ensure oxygen supply to the brain and prevent brain hypoxia injury. Recently, near infrared spectroscopy (NIRS) and its application in CPR has attracted widespread attention because it can monitor local oxygen saturation of frontal cortex brain tissue, and reflect the balance of oxygen supply and demand in real time. NIRS technology can be used to evaluate the quality of CPR, detect repeat arrest early, predict prognosis of patients, evaluate the level of autonomous regulation of cerebral blood flow, as well as monitor target temperature management and the treatment effect of patients with extracorporeal CPR. Hence, NIRS has good clinical application potential. This article mainly reviews the principle of NIRS and its application in CPR.

In order to obtain the acoustic emission parameters of different bedding coal and provide reference for the analysis and determination of its fracture mechanism and fracture precursors, the uniaxial compression acoustic emission experimental study of coal samples with bedding angles of 45°, 90° and 0° was carried out, the corresponding relationship between b values of coal samples with different loading angles and stress and energy was analyzed, the variation laws of acoustic emission parameters RA and AF values were studied, and the b value and r value under loading angle of 0 ° were analyzed. The results show that: after the peak stress, a large amount of energy is released, resulting in the penetration of micro cracks into large cracks. The b values of coal samples with loading angles of 45 ° and 90 ° are close to and significantly greater than that of 0 ° coal sample, and the b value of each specimen decreases after reaching the peak stress; when the loading angle is 45 °, the failure form of coal sample is tension shear composite failure. The loading angles of 90 ° and 0 ° are mainly tensile failure; the period of sharp decrease of b value is the same as that of sharp increase of r value, and r value can be used as an index to describe the degree of coal damage.

Active gear design is a method that can pre-control gear meshing performance directly. In order to study the influence of active gear design on the bearing characteristics of tooth surface, the relationship between active modification parameters of the face gear and bearing characteristics of tooth surface is studied. Firstly, the contact model of the gear pair is established by the finite element method, and then different groups of active modification parameters are designed for simulation analysis. The results show that the geometric transmission error greatly influences gear transmission stability and contact strength, and controlling its amplitude can control bearing transmission error amplitude. Pre-designed contact path inclination angle within 30° neighborhood, bearing contact characteristics are better. The contact ellipse length mainly affects the contact strength of tooth surface and bending strength of tooth root. According to the simulation results, when it takes 0.5～0.75 times of tooth width, face gear pair has better bearing contact characteristics.

In order to facilitate the selection of basic parameters in the initial design stage of face gear, and simplify the process of solving meshing strength of face gear pair. By referring to the existing strength calculation formula of the standard spur gear, the analytical calculation models of contact stress and bending stress of full tooth height of face gear were established. The curvature of tooth surface was solved by the basic parameters of the gear, and the contact stress of tooth surface was solved by the Hertz contact theory. The tooth thickness at the dangerous section of gear teeth was determined by the 30° tangent method, and the stress calculation coefficient table was given based on the expression of basic parameters of gear pair, finally, the analytical calculation formula of tooth root bending stress was deduced. Taking face gear pair with a certain design parameter as an example, the results obtained from the analytical calculation models were compared with those from the finite element simulation to verify the accuracy of models. On this basis, a simplified formula for calculating the strength of face gear was given which can be directly solved by the basic parameters of gear.

针对极少量带标签样本条件下的通信信号调制识别难题, 提出一种基于混合注意力原型网络的调制识别算法。综合元学习和度量学习的思想, 在原型网络框架下通过特征提取模块将信号映射至一个新的特征度量空间, 并通过比较该空间内各类原型与查询信号之间的距离确定查询信号调制样式。根据通信信号IQ分量的时序特点设计了由卷积神经网络和长短时记忆网络级联的特征提取模块, 并引入卷积注意力机制提升关键特征的权重; 采用基于Episode的训练策略, 使算法可泛化到新的信号识别任务中。仿真结果表明, 所提算法在每类信号只有5个带标签样本(5-way 5-shot)时平均识别率可达85.68%。

The rapid development of distributed photovoltaic power generation exercises an important influence on the current power dispatching operation and power market transactions. In the context of power market reform， this paper analyzes the organizational process for the participation of distributed photovoltaic power generation in power balance and the status quo of its participation in market trade； it summarizes the problems therein. Then based on the demands for market construction in China， the paper explores the process design of distributed photovoltaic power generation for the participation in power balance and related market-oriented mechanisms. Finally， the paper prospects for the key technologies that are urgently needed in the future to improve the monitoring， dispatching and control level of the power system for distributed photovoltaic power generation and establish a organization process and market-oriented mechanism of dispatching and production suitable for the development of distributed photovoltaic power generation.

Nuclear safety is a key component of the national security system, and it is the foundation and lifeline of the nuclear industry. Advanced and reliable nuclear safety technology is crucial for maintaining and improving intrinsic safety. Therefore, conducting strategic research on nuclear safety technologies is important for enhancing the nuclear industry in China. In this article, we conduct an in-depth research on China’s nuclear safety technology system using methods including academician interviews, field surveys, conference discussion, and literature review. The results show that, guiding by the overall national security and the nuclear safety concepts, China’s nuclear safety technology has made significant progress in recent years and its nuclear safety performance is good. However, China’s nuclear safety technology system still face several bottleneck problems. For example, the nuclear safety standards system needs improvement, the overall planning of nuclear safety software research and development is insufficient, and the precision and advanced nuclear safety equipment still depends on foreign countries. To continuously modernize the nuclear safety governance system and governance capacities and strengthen China’s nuclear industry, several suggestions are proposed. First, the nuclear safety standards system should be further improved. Second, independent nuclear safety software with high quality should be promoted by coordinating scientific research resources to tackle key problems. Third, government, industry, university, research, and application need to be coordinated to research and develop high-end nuclear safety equipment.

Objective To investigate the laboratory and clinical characteristics of acute lymphoblastic leukemia (ALL) with e1a3 BCR-ABL fusion protein. Methods The clinical data, and results of bone marrow cytology, flow cytometry, karyotyping, fluorescence in situ hybridization (FISH) and real-time fluorescence quantitative PCR of 2 ALL cases with e1a3 BCR-ABL fusion protein admitted in our department were collected and analyzed. The related literature was reviewed. Results Both cases presented ALL phenotype. FISH test showed BCR-ABL positive, and RQ-PCR (p190, p210, p230) negative. Finally, the rare BCR-ABL fusion gene test was added and the 2 patients were diagnosed as rare e1a3 BCR-ABL positive ALL. One patient received TKI treatment and had achieved complete remission for more than 4 months. Another patient did not receive TKI and died in longer than 1 month after diagnosis. Conclusion Multi-technique joint detection for fusion gene is helpful for the detection and diagnosis of ALL with e1a3 BCR-ABL fusion protein, and TKI therapy is helpful to improve the prognosis.

Aiming at 304 austenitic stainless steel paramagnetic material,a multi-class classification support vector machine LIBSVM algorithm was carried out for the magnetic anomaly inversion of weak magnetic signals. Orthogonal test design was used to make 4 testing samples with an artificial defect. The characteristics of artificial defect such as width,amplitude,and area were extracted for the collected magnetic anomalies of the defect signals. The LIBSVM algorithm was used to establish the relationship between the magnetic anomalies of the defect signals and the artificial defects. A total of 16 groups testing results indicate that 10 of the 16 defects inversion are correct in length and width,and 8 defects inversion are correct in depth. The inversion accuracy of defect length,width and depth is high,which provides a reference basis for the study of magnetic anomaly inversion for weak field signals,related experimental methods and equipment development.

The pollution is in the water while the source is on the shore.The pollutants in a river mainly come from the discharged onshore industrial and domestic sewage.Among them,the pollutants in the industrial wastewater from industrial enterprises have always been the difficulties in the environmental management of a river basin due to their large quantity,wide distribution,and complex types.Taking the electronics manufacturing industry,a key industry in the Shima River (Dongguan section) Basin,as a pilot,this paper puts forward a screening method for key industries in the basin from three aspects:the trend of regional development planning,the industrial economic structure of basin development,and the main pollution indicators.Then,it proposes a hierarchical evaluation standard system and differentiated management methods and further determines a management and control and risk prevention plan for water pollutant discharge from key industries in the basin to accumulate pilot experience for the supervision of industrial enterprises in the river basin.

Objective To analyze the landscape of genetic alterations of acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), myeloproliferative neoplasms (MPN), and myelodysplastic/myeloproliferative neoplasms (MDS/MPN). Methods Second-generation sequencing for common mutant genes was performed in the bone marrow cells derived from 305 myeloid leukemia patients (including 186 cases of AML, 64 cases of MDS, 27 cases of MPN, and 28 cases of MDS/MPN) treated in our hospital from January 2017 to January 2019. The gene mutation map was drawn. The mutation ratios of the genes and gene pathways of each myeloid tumor and the mutation rate of each mutant gene were compared among the different myeloid neoplasms. Results There were 606 mutations detected among 30 genes in the 305 cases. There were 15.4% cases with 0 mutation and 58.0% with more than 1 mutation. And up to 7 mutations were found in 1 case. Mutations of TET2, DNMT3A, NRAS, CEBPA, JAK2, C-KIT, U2AF1, and NPM1 were most common in the myeloid neoplasms. Mutations of signaling pathway-related genes accounted for over 50% in AML, MPN and MDS/MPN, and less than 10% in MDS. Mutations of transcription factors-related genes covered over 50% in AML, and less than 5% in MPN. Mutations of epigenetics-related gene were over 50% in all myeloid neoplasms. RNA splicing factors were mutated for over 30% in MDS and MDS/MPN, and less than 5% in AML. Mutations in signaling pathway-related genes such as NRAS and C-KIT were more prone to low mutation rates, and those of epigenetics-related genes such as TET2 and DNMT3A were more prone to high mutation rates. Conclusion The genetic landscapes are different among AML, MDS, MPN, and MDS/MPN. The mutation ratios of signaling pathway-related genes are quite low in MDS, so are the ratios of transcription factors-related genes in MPN. Meanwhile, the ratios of RNA splicing factors- and epigenetics-related genes are quite high in MDS and MDS/MPN, respectively.

Objective To identify the hub genes and signal pathways of glioblastoma multiforme(GBM) by microarray and bioinformatics analysis method, and to find out the potential markers for early diagnosis and targeted therapy of GBM. Methods The expression profiling data of GBM was obtained from the GEO database. R software was used to screen differentially expressed genes (DEGs), and DEGs was annotated using DAVID online tools for GO ontology and KEGG signaling pathway enrichment. Moreover, protein-protein interaction network(PPI) was constructed and from which the hub genes were selected. Finally, the TCGA database was used to validate the hub genes. Results Samples Pearson correlation analysis showed that the expression profiling was reliable. Totally 2142 DEGs including 968 up-regulated genes and 1174 down-regulated genes were screened. GO and KEGG enrichment showed that the DEGs mainly correlated with cell cycle, cell division and proliferation, synaptic transmission and other biological functions and pathways. Pathway network analysis indicated that MAPK signal pathway played a core regulatory role in the network. In addition, 9 hub genes most related to GBM were screened from PPI network, and further confirmed by TCGA database. Conclusion KEGG signaling pathways and hub genes may reveal the molecular mechanism of the development of GBM, and the hub genes may be used as the molecular marker for early diagnosis and therapeutic targets of GBM.

To manufacture face gear with high precise, computer numerical controlled ( CNC ) grinding method and grinding disk in face gear machining was investigated. The tooth surface equation of face gear machined by grinding disk was determined by coordinate transformation. The motion laws of CNC machine were established by the equivalence principle of position and movement of tool in different machining method, and then the laws were transformed into Taylor expansion for convenient programming. The deviation of CNC machining tooth surface from that of theoretical was calculated, in an illustrated example the maximal deviation was 0.0719 micrometers. The result shows that the grinding method of face gear is feasible, the CNC motion laws are correct and the desired precision is easy to meet. [ABSTRACT FROM AUTHOR]

Spherical helical gears with tooth flank modification were proposed to enhance loaded capacity anti improve the sensitivity to assemble errors. The mathematical model of tooth surface was developed by the imagine rack-cutter and gearing theory, and the modification with parabolic curve of rack-cutter was applied to produce a required transmission error curve and improve meshing characteristics. Then, the tooth contact analysis model was established on the conditions of continuous tangency of two contact surface, of which the assemble errors were considered. The simulation results show that the capacity of loaded capacity and tooth contact ratio can be increased by the contact pattern of convex-concave type gears along the helical tooth traces, and the error sensitivity of contact pattern of the convex-convex and convex-helical types of spherical gears can be improved by tooth modification. [ABSTRACT FROM AUTHOR]

Objective To analyze the trends and hotspots in research related to microbiomes and microbes of dental caries; in addition, the study seeks to provide a reference for caries research. Methods We searched the Web of Science Core Collection (WOSCC) to extract relevant literature in the field of microbiomes and microbes of dental caries published from 2014 to 2023. We used bibliometric visualization evaluation methods such as CiteSpace to conduct visualized analysis of factors that include the number of publications, journals, countries, authors, institutions, co-cited references, and keywords. Results A total of 3 192 references were extracted, including 2 664 articles and 528 reviews. The number of annual publications is increasing. The United States and China lead the number of publications, with the United States demonstrating a greater capacity for international collaboration. The top 10 journals in percentage of literature are mainly in the field of dentistry followed by the field of microbiology. The author cooperation networks with the highest number of publications include the network led by Zhou Xuedong of Sichuan University, and the network led by Xu Hockin H.K and Weir Michael D of the University of Maryland, Baltimore. The research on microbiomes and microbes of dental caries focuses on the cariogenic toxicity and interaction of microorganisms, oral microbiomes, and the relationship between dental caries and systemic diseases. The articles with high citation frequency mainly involve topics such as dental caries, oral biofilm, oral microbiota, and Streptococcus mutans. Keyword research showed that “dental caries,” “Streptococcus mutans,” “bacteria,” “dental plaque,” and “antibacterial activity” have been the primary focus of research in the last decade. The number of keywords, such as “health” and “oral health,” is on the rise. The latest emergence of “gut microbiome/microbiota” suggests that the oral gut microbiome axis is at the forefront of research in this field, and researchers’ focus is gradually shifting toward the connection between dental caries and systemic diseases. Conclusion Over the last decade, the number of publications in the field microbiomes and microbes of dental caries has increased annually. This research trend will be the multi-omics of the overall oral microbiome, and new research methods and techniques will contribute to the field of cariology.

Objective: To compare the efficacy of conventional in vitro fertilization (IVF)and intracytoplasmic sperm injection (ICSI)in older patients with poor ovarian response. Methods:The data of 381 in vitro fertilization-embryo transfer (IVF-ET) cycles of older patients (≥ 40 years old)with poor ovarian response were analyzed retrospectively. Those cycles were divided into two groups, IVF group (conventional IVF, 200 cycles) and ICSI group (181 cycles). Fertilization rate and clinical pregnancy rate were compared between two groups. Results: The fertilization rate and clinical pregnancy rate in the IVF group were insignificantly higher than those in the ICSI group, while the rate of effective cycles and high quality embryos in the ICSI group were very limitedly higher than those in the IVF group. However, there were not statistically differences in those rats between two groups (P>0.05). Conclusions: ICSI treatment did not increase fertilization rate and clinical pregnancy rate in IVF-ET cycles in those patients at ≥ 40 years with poor ovaian response. [ABSTRACT FROM AUTHOR]

In order to research the influence of installation errors and support deformations on load distribution in the torque split transmission system of face gear,a calculating method for load distribution of torque split transmission system of face gear is proposed. At first,the model of load sharing for torque split transmission system of face gear is established by torque balance equation and deformation compatibility condition,and the deformation compatibility condition directly relate to time- vary meshing stiffness of gear pair. Secondly,the force on the face gear is analyzed,and the form that the deformation of support system is described,the support deformation is translated to errors of gear. Thirdly,the meshing stiffness of gear pair is fit as function of load by tooth contact analysis（ TCA） and loaded tooth contact analysis（ LTCA）. At last,the calculation method for coefficients of load sharing is proposed. Numerical example demonstrates that the coefficients of two path in the system is respectively 0. 65 and 1. 35 under the combined effects of installation errors and support deformation,while the radial support deformation ax1 of the pinion is- 692. 3 μm,the coefficients of the two path is respectively 0. 987 0 and 1. 013. Hence,the radial elastic support ax1 of the pinion,to some extent,is able to offset the influence of unequal torque splitting caused by installation errors and support deformation.

Alzheimer’s disease (AD), a common neurodegenerative disease, has been linked to periodontitis, especially Porphyromonas gingivalis (P. gingivalis) infection. This review summarizes the potential mechanisms and pathways through which P. gingivalis and its virulence factors are involved in AD pathogenesis, aiming to provide the scientific basis for the development of novel prevention and treatment strategies for AD. P. gingivalis can promote AD by exacerbating neuroinflammation, facilitating amyloid beta and Tau deposition, and disrupting the blood-brain barrier. Gingipains, secreted by P. gingivalis, serve as core effector molecules by increasing the blood-brain barrier permeability. The association between P. gingivalis and its effectors and AD pathology has been validated by metagenomic analysis and sample detection, indicating that P. gingivalis may be an environmental susceptibility factor or modifiable risk factor for AD. However, the precise mechanisms by which P. gingivalis influences AD, and its interactions with other potential AD-related factors, remain unclear. Moreover, further research needs to be conducted on the therapeutic potential of P. gingvalis intervention in improving AD.

Droplet-based microfluidics is a technology that generates and manipulates highly uniform droplets, ranging from picoliter to nanoliter droplets, in microchannels under precise control. In biological research, each droplet can be used to encapsulate a small group of cells or even a single cell, and then serve as an individual container for biochemical reaction, which is well suited for high-throughput and high-resolution biochemical analysis. In the field of microbial research, from cultivation and identification of microbes to the investigation of the spatiotemporal dynamics of microbial communities, from precise quantitation of microbiota to systematic study of microbial interactions, and from the isolation of rare and unculturable microbes to the development of genetically engineered strains, droplet microfluidic technology has played an important promotional role in all these aspects. Droplet microfluidics shows potential for becoming a basic tool for exploring single-cell microbes in microbiological research. In this review, we gave a brief overview of the technical basis of droplet microfluidics. Then, we presented its latest applications in microbial research and had some discussions, aiming to provide a reference for relevant research on microorganisms., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

The taste buds in the human tongue contain specialized cells that generate taste signals when they are stimulated. These signals are then transmitted to the central nervous system, allowing the human body to distinguish nutritious substances from toxic or harmful ones. This process is critical to the survival of humans and other mammals. A number of studies have shown that dysgeusia, or taste disorder, is a common complication of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which can severely affect patients' nutritional intake and quality of life. Based on the physiological process of taste perception, the direct causes of dysgeusia include dysfunction of taste receptors and damage to the taste nervous system, while indirect causes include genetic factors, aging-related changes, bacterial and viral infections, and cancer treatments such as radiotherapy and chemotherapy. The pathogenic factors of dysgeusia are complicated, further research is needed to fully understand the underlying mechanisms, and some of the reported findings and conclusions still need further validation. All these form a great challenge for clinical diagnosis of the cause and targeted treatment of dysgeusia. Herein, we reviewed published research on the physiological process of taste perception, the potential mechanisms of taste disorders related to SARS-CoV-2 infection, and strategies for prevention and treatment, providing theoretical support for establishing and improving the comprehensive management of COVID-19 complicated by taste disorders., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Cyclic dimeric adenosine 3',5'-monophosphate (c-di-AMP) is a newly-discovered second messenger in bacteria and archaea. By directly binding to or affecting the expression of target proteins, c-di-AMP regulates the physiological functions of bacteria, including maintaining osmotic pressure, balancing central metabolism, monitoring DNA damage, and controlling biofilm and spore formation. As a new pathogen-associated molecular pattern (PAMP), it binds to the host pattern recognition receptor (PRR), induces cyclic GMP-AMP synthase (cGAS)-STING signal axis to produce type Ⅰ interferon by activating the stimulator of interferon genes (STING), and promotes the secretion of inflammatory factors through nuclear factor κB (NF-κB) signaling pathway, thereby playing an important role in host immunity to bacterial infection and tumorigenesis. Due to its immunogenicity, c-di-AMP could be used as an immune adjuvant to provide new targets for the development of vaccines. However, the specific mechanism of action of c-di-AMP in host immunity awaits further exploration. Herein, we presented the structure and biological characteristics of c-di-AMP, and summarized the possible mechanism of c-di-AMP's regulation of host immune response. In addition, we also reported the latest findings on using c-di-AMP as an immune adjuvant in clinical treatment. Research on the function of c-di-AMP and its mechanism of action on host immune response provides new ideas for finding clinical solutions to bacterial resistance, infection control, tumor prevention, and vaccine development in the future., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Objectives: To screen small-molecule antibacterial drugs and investigate the antibacterial effect and mechanism of selective estrogen receptor modulators (SERMs) against Streptococcus mutans (S.mutans) ., Methods: The minimum inhibitory concentration of 426 Food and Drug Administration (FDA)-approved small-molecule drugs against S. mutans was determined using the microdilution method, and the target of SERMs acting on S. mutans was explored by employing a random transposon mutant library., Results: Among the 426 FDA-approved SERMs, toremiphene, tamoxifen, clomiphene, and raloxifene exhibited excellent antibacterial effects against S.mutans . Results of mutant library screening showed that the two mutant strains were resistant to clomiphene. The gene sequence of the resistant strains showed that the transposon insertion sites were located in the genes of smu_546 and smu_874 ., Conclusions: SERMs, such as toremifene, tamoxifen, clomiphene, and raloxifene, exerted obvious antibacterial effects on S. mutans , and their targets may be proteins expressed by smu_546 and smu_874 gene.

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been raging across the world for over two years, but the daily reported numbers of new infections and deaths are still increasing. The newly identified Omicron variant has significant changes in its transmissibility and pathogenicity due to the multiple mutations in the spike protein, posing new challenges to the global public health. World Health Organization has categorized Omicron as a variant of concern (VOC). The spread of SARS-CoV-2 and its variants has caused disruptions to the dental practice worldwide. During the course of diagnosis and treatment of dental care, face-to-face communication at close quarters, droplets, aerosols, and exposure to saliva and blood increase the risks of SARS-CoV-2 transmission. The emergence of new variants, especially the Omicron variant, has formed new challenges to dental healthcare provision. In addition, oral tissues, including the tongue and oral mucosa, can overexpress the angiotensin converting enzyme 2 (ACE2), which is also the binding receptors of SARS-CoV-2. As a result, the oral cavity is one of the target sites of SARS-CoV-2 infection. SARS-CoV-2 infection in oral cavity may cause different oral complications, such as loss of taste. However, there are few reports about Omicron and the other variants of SARS-CoV-2 and their impacts on dental healthcare provision. Herein we made an overview of the Omicron variant and its characteristics, including its pathogenicity and immune evasion, and its potential impact on dental practice. We also proposed some control measures with the aim of reducing the possible transmission of SARS-CoV-2 and its variants during dental care., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Objective: To study the effects of CD47-targted immunotherapy on the oral-gut microbiota of immune-competent mice., Methods: A peritoneal metastatic colon cancer model was constructed in immune-competent mice. Anti-CD47 monoclonal antibody was intraperitoneally administered to the mice in the treatment group, while PBS was administered to mice in the control group. Tumor growth was documented with small animal live imaging technology. 16S rRNA sequencing technology was used to analyze the composition and diversity of oral-gut microbiota., Results: The alpha diversity of oral microbes in the anti-CD47 monoclonal antibody treatment group decreased, and the difference was statistically significant. There was no significant change in the alpha diversity of gut microbes. Differential species analysis showed significantly decreased abundance of Staphylococcus , Jeotgalicoccus , and Sporosarcina in the oral microbiota of mice in the treatment group compared to that of mice in the control group. The abundance of Bacteroides in the gut microbiota was significantly higher in the treatment group., Conclusion: CD47-targted immunotherapy has a rather significant impact on the diversity of oral microbiota in mice, but does not have significant impact on the species diversity of gut microbiota., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Oral Microbiology is a vital component of the basic science of stomatology and an important compulsory course for undergraduate students of stomatology, focusing on the oral microbiology and microecology, the pathogenesis of oral infectious diseases, and the relationship between oral microbes and human health. Our faculty team have made reforms of the theory and laboratory teaching of the course Oral Microbiology . We have introduced in the classroom the concept of Three Comprehensive Approaches to Education- the full involvement of everyone, the through-course approach and all-round education-and offered inquiry-based instruction through a combination of extracting the core information from every chapter, using the core information as the foundation, integrating the core information with clinical problems, and using experiment operation to foster in the students an attitude of solving clinical problems through research. These teaching innovations improved the undergraduate students'motivation to learn. We evaluated the teaching effect with questionnaire surveys. The results suggested that the students showed high interest in learning and were satisfied with our teaching innovations. In addition, student performance evaluation for the course showed significant improvement, indicating that the instructional reform program of Oral Microbiology was conducive to students'understanding and mastery of the course content, improved student motivation to learn and their grades, and received positive reviews from the students. We report herein, from three aspects, the course innovations and the experiences gained. We discussed the significance of integrating ideological and political theories teaching in all courses and using innovative teaching materials and teaching models and, highlighted their importance in the education of stomatology students, and proposed suggestions to further improve the course design of Oral Microbiology ., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Nitrogen metabolism pathways mediated by microorganisms play an important role in maintaining the structure and functional stability of soil ecosystems. Clarifying the relationships between microbial communities and nitrogen metabolism pathways can expand our understanding of nitrogen metabolism pathways at a microscopic level. However, the horizontal gene transfer of microorganisms means that taxonomy-based methods cannot be easily applied. A growing number of studies have shown that functional traits affect community construction and ecosystem functions. Using methods based on functional traits to study soil microbial communities can, therefore, better characterize nitrogen metabolism pathways. Here, five typical forest soils in China, namely black soil(Harbin, Heilongjiang), dark-brown earth(Changbaishan, Jilin), yellow-brown earth(Wuhan, Hubei), red earth(Fuzhou, Fujian), and humid-thermo ferralitic soil(Ledong, Hainan), were selected to study the traits of nitrogen metabolism pathways using metagenomic technology combined with the trait-based methods. The studied nitrogen metabolism pathways were ammonia assimilation, nitrate dissimilatory reduction, nitrate assimilatory reduction, denitrification, nitrification, nitrogen fixation, and anaerobic ammonia oxidation. The results showed that bacteria dominated the metagenomic library, accounting for 98.02% of all the sequences. Across all domains, the most common pathway was ammonia assimilation. For example, an average of 2830 ammonia assimilation pathway genes were detected for every million annotated bacterial sequences. In comparison, nitrogen fixation and anaerobic ammonia oxidation were the least detected pathways, accounting for 28.3 and 10.7 per million sequences, respectively. Different microorganisms can participate in a same nitrogen metabolism pathway, and the community structure of different soils was variable. The five typical forest soils in China show the same microbial nitrogen metabolism pathway traits; however, the community structure of the microorganisms mediating these processes was found to vary.

Objectives: To identify the alternative splicing isoform of mouse sweet taste receptor T1R2, and investigate the effect of lipopolysaccharide (LPS) local injection on T1R2 alternative splicing and the function of sweet taste receptor as one of the bacterial virulence factors., Methods: After mouse taste bud tissue isolation was conducted, RNA extraction and reverse transcription polymerase chain reaction (PCR) were performed to identify the splicing isoform of T1R2. Heterologous expression experiments in vitro were utilized to detect how the T1R2 isoform regulated the function of sweet taste receptors. The effect of local LPS injection on the expression of the T1R2 isoform was measured by real-time fluorescent quantitative PCR., Results: T1R2 splicing isoform T1R2_Δe3p formed sweet taste receptors with T1R3, which could not be activated by sweet taste stimuli and significantly downregulated the function of canonical T1R2/T1R3. Local LPS injection significantly increased the expression ratio of T1R2_Δe3p in mouse taste buds., Conclusions: LPS stimulation affects the alternative splicing of mouse sweet taste receptor T1R2 and significantly upregulates the expression of non-functional isoform T1R2_Δe3p, suggesting that T1R2 alternative splicing regulation may be one of the mechanisms by which microbial infection affects host taste perception.

Veillonella species, known as the early colonizer of oral biofilm, are prevalent in oral microbiota. Seven Veillonella species have been isolated from oral cavity. Their distribution varies not only with different people but also with different sites in the oral cavity. Oral Veillonella are associated with oral diseases. They contribute to the adhesion of Streptococcus mutans and consume the lactate generated by streptococci. Veillonella species play an important role in the occurrence and development of periodontal diseases by providing adhesion sites for Porphyromonas gingivalis and boosting immune responses. The production of lipopolysaccharide and H2S is related to other oral diseases, such as pulpitis, periapical periodontitis, and halitosis. Several studies have been conducted on the relationship between Veillonella and oral diseases and the interaction between Veillonella and other pathological microorganisms, but limited knowledge is available at the molecular level. This article reviews the research progress in the relationship between Veillonella and oral infectious diseases, such as dental caries and periodontal diseases.

Periodontal disease is a common oral disease that can cause irreversible damage of periodontal support tissue. Studies on the relationship between periodontal disease and malignancies have also increased. In this review, the relationship between periodontal disease and gastrointestinal malignancies (e.g., stomach cancer, colorectal cancer, and pancreatic cancer), lung cancer, and breast cancer are discussed. The related mechanisms are summarized in terms of four aspects, namely, immu-nity, inflammation, gene, and microbiota and its products, to provide novel methods for the prevention and early diagnosis of malignancies.

Objective To develop and verify a medical microdevice for analyzing the three-dimensional(3D)migration of tumor cells in extracellular matrix. Methods The mold of the microdevice was made by precision machining,and then the medical microdevice based on polydimethylsiloxane(PDMS)-glass was obtained by PDMS casting,moulding,and bonding.During the analysis,the suspension of tumor cells and matrigel were mixed and then added into the migration channel of microdevice,and the controllable migration of tumor cells in matrigel was induced by establishing chemokine concentration gradient on both sides of the migration channel.Meanwhile,the migration process of tumor cells was recorded with the live cell dynamic imaging device. Results Breast cancer cell line MCF-7 was taken as an example to verify the feasibility of the microdevice to control and dynamically monitor the 3D migration process of tumor cells in vitro.Qualitative analysis of imaging data showed that the migration of MCF-7 cell lines in matrigel was determined by the concentration gradient distribution direction of chemokine and presented as the amoeboid-like migration mode.The proportion and migration velocity of MCF-7 cells could be quantified by the quantitative analysis of cell migration process.The inhibition ability of matrix metalloproteinase inhibitors(Batimastat)and adenosine triphosphatase inhibitors(Blebbistation)on the 3D migration behavior of MCF-7 cells was found to be different. Conclusion This device can be used for in-depth analysis of tumor cell migration and its mechanism and for evaluating the efficacy of anti-metastatic drugs.

AMP-activated protein kinase (AMPK) is a key enzyme in the regulation of cellular energy homeostasis. Recent studies demonstrated that AMPK also plays an important role in the modulation of inflammation, an energy-intensive molecular response. The commonly used AMPK activators include 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) and A-769662. In addition, the biological activities of metformin and adiponectin are closely related to activation of AMPK. Numerous studies have shown that these AMPK activators play an effectively protective role in animal models of acute lung injury, asthma, colitis, hepatitis, atherosclerosis and other inflammatory diseases. Therefore, AMPK activators may have promising potential for the prevention and treatment of inflammation related diseases.