Joint Section Research Articles

Experimental research on the mechanical behavior of segmental joints of shield tunnel reinforced with a new stainless steel corrugated plate

Shield tunnels are inevitably damaged by complex diseases during operation, so repair and reinforcement are essential. The stainless steel corrugated plate (SSCP) has many advantages for tunnel structure reinforcement because of its high strength, lightweight, convenient construction and installation, and corrosion resistance. Mechanical behaviors of an unreinforced segmental joint and a segmental joint reinforced with a new SSCP were investigated by full-scale tests. The reinforcement test took into account the actual reinforcement conditions in the field, i.e. the joint bore the load alone before reinforcement, maintained the load during reinforcement, and bore the load together with the SSCP after reinforcement. The experimental results demonstrate that: (1) both unreinforced and reinforced joints exhibit a compressive-flexural failure mechanism, and their failure is manifested by concrete crushing in the compressed zone of the joint. (2) Compared to that unreinforced joint, the bending moment and ultimate vertical load of the reinforced one are increased by 73.7% and 119.3%, respectively. And the reinforced joint is stiffer than the unreinforced one, reflecting that SSCP reinforcement enables higher stiffness. (3) Trends of strain-moment curves of the bent bolts and concrete are similar in the unreinforced and reinforced joints. Under the same load, the strains in the reinforced group are smaller than those in the unreinforced group, indicating that the SSCP in the reinforced group shares the load. (4) The strains of the SSCP exhibits a symmetrical distribution in the length direction with the joint section as the symmetrical plane. The strains at the trough show tensile strain, while the strains at the crest show compressive strain. The combined force of the corrugated steel plate cross-section is tensile (i.e., SSCP shares the tension load in the tensile zone of the joint), reflecting the reinforcement effect of SSCP.

SELECTION OF A WELDING ELECTRODE TO PREVENT CONTACT CORROSION OF A STEEL 1.0402 WELD JOINT

Welded structures operate, as a rule, under conditions of simultaneous exposure to aggressive media and workloads. Thus, when protecting the metal of welded joints from corrosion fatigue, a number of specific problems arise due to the heterogeneity of their structure, the presence of multilayer welds, physical and geometric stress concentrators, and the staged nature of the change in the fine structure of the metal during fatigue loading. The result is an accelerated destruction of the metal in the junction zones of various structural forms, which are unequally adapted to the action of fatigue stresses. This fully applies to such critical structures of the oil and gas industry as pipelines, tanks, gas holders, etc. The purpose of the research was to establish the features of corrosion of welded joints made by various brands of electrodes by analyzing the change in the value of the electrode potential of the metal, which reflects the level of free energy of the surface layers in dynamics. Laboratory samples of carbon steel 1.0402 were subjected to manual arc welding (OZL-6, LB-52, MP-3 electrodes) and semi-automatic welding (EMK 6D polished wire and E71T1 rutile flux-cored welding wire with rapidly crystallizing slag). Further, their microstructural analysis was carried out and the hardness of various sections of welded joints was determined. It has been established that samples welded by semi-automatic welding are less susceptible to corrosion damage, since the distribution of electrode potentials in the zones of the welded joint indicates their lower structural inhomogeneity. In this case, general uniform corrosion takes place. In addition, the use of EMK 6D and E71T1 welding wires ensures better mechanical properties of welded joints.

3-D Numerical Simulation of Seismic Response of the Induced Joint of a Subway Station

In recent times, induced joints have been set along the length of subway stations in order to avoid disordered cracking of the main structures occurring due to temperature stress, concrete shrinkage, creep, or uneven foundation settlement. At present, the use of induced joints in subway station structures is mainly based on engineering experience. The seismic response of induced joints has not yet been well explained, much less mastered. In this study, a 3-D numerical model of a subway station incorporating certain sorts of induced joints is established systematically. Then, the seismic response of those induced joints applied in different positions and various forms has been studied under different seismic waves by varying the spectral characteristics and peak acceleration values of the waves. The results show that the horizontal relative sliding displacement of the structures on both sides of an induced joint increases gradually from bottom to top along the structure of the subway station. While the vertical sliding displacements that occur along the section width are larger at both ends of the induced joints than in the middle. What is more, with an increase in seismic intensity, the horizontal relative sliding displacement becomes larger, while the vertical displacement becomes even smaller. In addition, the relative sliding displacement can be reduced by increasing the residual longitudinal reinforcement ratio of the induced joint. Furthermore, it is discovered that the setting of key grooves at the bottom plate of the induced joint section has a certain effect on controlling the horizontal relative sliding displacement, as well as a significant effect on preventing the vertical relative dislocation of the structures on both sides of the induced joint.

An integrated network pharmacology approach reveals that Darutigenol reduces inflammation and cartilage degradation in a mouse collagen-induced arthritis model by inhibiting the JAK-STAT3 pathway

Ethnopharmacological relevanceDarutigenol (DL) is a natural active product derived from the Chinese herbal medicine Sigesbeckia glabrescens (Makino) Makino. It is administered as a traditional Chinese medicine (TCM) to dispel rheumatism, benefit the joints, and detoxify. However, its potential mechanism in the treatment of rheumatoid arthritis (RA) remains unknown. Aims of the studyThe objectives of this research were to determine the effects and elucidate the modes of action of DL on RA-related joint inflammation. Materials and methodsNetwork pharmacology and molecular docking were used to screen and validate candidate DL targets for RA treatment, respectively. A DBA/1 mouse rheumatoid arthritis model was induced with bovine type II collagen. Intragastric DL administration was followed by the calculation of the clinical arthritis index. A section of the ankle joint was excised and stained and the pathological changes in it were observed. Enzyme-linked immunosorbent assays (ELISA) and western blotting (WB) were used to clarify the mechanisms of DL in RA treatment. ResultsDL effectively attenuated the inflammation, mitigated the articular cartilage degradation, and bone erosion, and alleviated the inflammatory joints associated with RA. Network pharmacology screened six key targets of DL while molecular docking revealed that it docked well with its protein targets. The DL treatment group presented with significantly less ankle joint redness and swelling, a lower arthritis index scores and serum and bone marrow supernatant IL-6 levels, more complete ankle joint surfaces, and less synovial inflammation, cartilage degradation, and bone erosion than the collagen-induced arthritis (CIA) group. The DL treatment also substantially downregulated the Janus kinase (JAK)1, JAK3, matrix metalloproteinase (MMP)2, MMP9, and phospho-signal transducer and activator of transcription (p-STAT)3 proteins in the joints. ConclusionsTo the best of our knowledge, the present work was the first to demonstrate that DL has significant anti-inflammatory efficacy and reduces cartilage degradation and bone erosion. It also demonstrated that the anti-RA effect of DL may be explained by its ability to inhibit joint inflammation and reduce articular cartilage degradation through the interleukin (IL)-6/JAK1,3/STAT3 axis and downregulate MMP2 and MMP9. Hence, DL might play a therapeutic role in a mouse RA model.

Anti-rheumatoid arthritis potential of Rhododendron molle G. Don leaf extract in adjuvant induced arthritis rats.

The aim of this study was to test the anti-rheumatic arthritis effects of Rhododendron molle G. Don leaf extract in arthritis rats and inflammatory RAW 264.7cells. Preliminary analysis and comparison of potential medicinal components of three polar extracts by HPLC and UHPLC-Q-TOF-MS. SD rats were subcutaneously injected with complete Freund's adjuvant (CFA) to induce inflammation on the right hind paw. RAW 264.7cells were induced by lipopolysaccharide (LPS) to established cell inflammatory model. The volume of rat hind paw was measured with a volume meter to detect swelling, and the weight of rats was measured with an electronic balance. The severity of arthritis in rats was evaluated by arthritis score. The pathological sections of rat hind paw joints were observed by hematoxylin-eosin staining, and the contents of IL-6 and IL-1β in serum were detected. qRT-PCR was used to detect the expression of IL-1β, IL-6, TNF-α and COX-2 genes in RAW 264.7cells. The release of nitric oxide was measured by Griess reaction. The expression levels of IL-6 and IL-1β were detected by Western-Blot. and discussion: The chloroform extract from R. molle leaves (CERL), Ethyl acetate extract from R. molle leaves (EERL), n-butanol extract from R. molle leaves (BERL) could significantly inhibit hind paws swelling and reduce arthritis index in arthritis rats. And it showed dose dependence. Compared with tripterygium glycosides (TG) tablets, an effective drug of RA treatment, CERL have better anti-RA effect after administration. In addition, the three kinds of the polar extracts of Rhododendron molle leaves (PERL) had lower toxicity, with the LD50 279.87, 239.65, 500.08 (mg/kg) respectively, while TG group's LD50 was 96.00 (mg/kg). In vitro experiments showed that the three PERLs can significantly inhibit the level of pro-inflammatory factors and inflammatory mediator, such as TNF-α, IL-1β, IL-6, COX-2 and NO, which were consistent with their anti-RA ability. Among the three kinds of PERLs, CERL showed the best inhibitory activity. The R. molle leaf is a potential medicinal part for the treatment of RA. This study explored the anti-RA and anti-inflammatory activities of CERL, EERL, BERL, which laid a foundation for further promoting the clinical application of R. molle.

Organic metal matrix Mil-88a nano-enzyme for joint repair in the osteoarthritis mouse model.

Introduction: In this paper we tried to conduct a novel nanomaterial strategy to overcome osteoarthritis (OA) in a mouse model. Methods: In this regard, after synthesizing the Mil-88a nanozyme, as a certain Fe-MOF, its toxic effects were detected by CCK-8 method and live-dead staining. The OA model of mouse was constructed, and paraffin sections of joints were taken for histological evaluation. In addition, immunofluorescence and immunohistochemistry were used to identify the OA progression and OARSI was used to evaluate the OA grades. We observed that Mil-88a could be easily synthesized and has high biocompatibility. Results: We observed that Mil-88a could significantly promote the expression of OA anabolism-related genes such as Col2 and also significantly inhibit the expression of OA catabolism-related genes MMP13. Besides, we observed better OARSI score in animals treated with Mil-88a nano-enzyme loading on organic metal matrix. Discussion: Overall, Mil-88a nano-enzyme could be used as a novel strategy to treat OA.

Folate Receptor‐Targeted NIR‐II Dual‐Model Nanoprobes for Multiscale Visualization of Macrophages in Rheumatoid Arthritis

AbstractRheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation. Macrophages accelerate the pathological process of RA through the continuous cell accumulation and secretion of cytokines. Therefore, multiscale visualization of macrophages is of great significance for the early diagnosis of RA. In this work, folate receptor‐targeted Cptnc‐4F nanoprobes, named FA‐CF‐NPs, are developed for dual‐model molecular imaging of macrophages in RA mouse models. FA‐CF‐NPs exhibit complementary imaging advantages with high fluorescence sensitivity and resolution in the second near‐infrared window (NIR‐II) and promising photoacoustic (PA) imaging contrast with deep tissue penetration. The high affinity of the folate ligand on the surface of FA‐CF‐NPs to macrophages with overexpressed folate receptors ensures the specific targeting function of the nanoprobes for imaging in vivo. FA‐CF‐NPs are employed to achieve NIR‐II fluorescence imaging to accurately localize macrophages in the joint, obtaining a high signal‐to‐background ratio (SBR) of 15.5. Meanwhile, PA imaging is also performed to observe macrophage distribution in the longitudinal section of the whole joint. Moreover, macrophage infiltration is detected in the joint of RA mice with the absence of RA pathologies such as synovitis and cartilage loss. The results provide an opportunity for in vivo macrophage tracking and early diagnosis of RA.

Bibliometric Analysis of AANS/CNS Joint Section on Tumors (JST) Award Recipients

Bibliometric Analysis of AANS/CNS Joint Section on Tumors (JST) Award Recipients

Microstructural characteristics and mechanical properties of 7075 aluminum alloy foam sandwich panels fabricated via integrated forming and foaming

A new integrated forming and foaming method based on friction stir welding (FSW) was proposed for foam sandwich panels. The microstructure characteristics of the precursors and foams with different welding parameters were analyzed using optical microscopy and scanning electron microscope (SEM/EDS). The temperature field and flow field of foam precursor joint in FSW were simulated by Fluent CFD software. The microstructural characteristics of foam precursor after hot forming were analyzed using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The effect of foam precursor deformation on foam evolution was also investigated. The results show that the formability of foam precursor is the same as that of rolled plate. Aluminum foam sandwich panel with homogenous pore structure is prepared at 680 °C for 225 s. After hot forming, the equiaxed recrystallized grain is obtained, and the dislocation and the second phase provide reinforcement. In addition, Rgoss{110}〈110〉 texture component strength increases. When the tensile strain is 0.15, smaller and more uniform pores are produced. Numerical simulations show that the peak temperature gradually decreases with the increase of the distance of the stirring head center. In addition, the temperature on the advancing side (AS) is higher than that on the retreating side (RS). When the tool travel speed is 50 mm/min and rotational speed is 2000 r/min, the maximum material flow velocity at the joint section is 184.2 mm/s and the highest concentration of powder tracing particles is 0.0123 kg/m3. It is proved that the integrated forming and foaming method can solve the problem in manufacturing of complex curved AFS components.

Investigation into the Effect of Interlock Volume on SPR Strength

During the design of automotive structures assembled using Self-Piercing Rivets (SPRs), a rivet and die combination is selected for each joint stack. To conduct extensive physical tensile testing on every joint combination to determine the range of strength achieved by each rivet-die combination, a great deal of lab technician time and substrate material are required. It is much simpler and less material-consuming to select the rivet and die solution by examining the cross sections of joints. However, the current methods of measuring cross sections by measuring the amount of mechanical interlock in a linear X-Y direction, achieved with the flared rivet tail, do not give an accurate prediction of joint strength, because they do not measure the full amount of material that must be defeated to pull the rivet tail out of the bottom sheet. The X-Y linear interlock measurement approach also makes it difficult to rapidly rank joint solutions, as it creates two values for each cross section rather than a single value. This study investigates an innovative new measurement method developed by the authors called Volumelock. The approach measures the volume of material that must be defeated to pull out the rivet. Creating a single measurement value for each rivet-die combination makes it much easier to compare different rivet and die solutions; to identify solutions that work well across a number of different stacks; to aid the grouping of stacks on one setter for low-volume line; and to select the strongest solutions for a high-volume line where only one or two different stacks are made by each setter. The joint stack results in this paper indicate that there is a good predictive relationship between the new Volumelock method and peel strength, measured by physical cross-tension testing. In this study, the Volumelock approach predicted the peel strength within a 5% error margin.

Social media insights for neurosurgical oncologists: a survey of the American Association of Neurological Surgeons and Congress of Neurological Surgeons Joint Section on Tumors.

There is a paucity in the literature regarding the characteristics and attitudes of social media (SM) utilization in a professional manner by neurosurgical oncologists. A 34-question electronic survey was created using Google Forms and disseminated via email to members of the AANS/CNS Joint Section on Tumors. Demographic data were compared amongst those who utilize social media versus those who do not. Factors associated with positive effects of professional SM use and with having more followers on SM were analyzed. The survey received 94 responses, of which 64.9% reported that they currently use SM in a professional manner. Age < 50 years was found to be associated with SM use (p = 0.038). Facebook (54.1%), Twitter (60.7%), Instagram (41%), and LinkedIn (60.7%) were the most used SM platforms. Having a higher number of followers was associated with practicing in academics (p = 0.005), using Twitter (p = 0.013), posting about their own research publications (p = 0.018), posting interesting cases (p = 0.022), and posting about upcoming events (p = 0.001). Having a higher number of followers on SM was also associated with positive effects, specifically new patient referrals (p = 0.04). Neurosurgical oncologists can benefit by using social media professionally for increased patient engagement and networking within the medical community. Practicing in academics, making use of Twitter, and posting about interesting cases, upcoming academic events, and one's own research publications can help gain followers. In addition, having a large following on social media could lead to positive effects such as new patient referrals.

A bioinspired modular soft robotic arm

A human arm is a vital instrument for performing various tasks. To imitate natural design, we developed and characterized a bioinspired modular soft robotic arm fabricated from fabric thermoplastic polyurethane (TPU). The soft robotic arm comprises three link sections, three joints, and an end-effector. Although some soft robotic arms have been designed, they are primarily fabricated with continuous shapes. Therefore, we fabricated a modular and customizable soft robotic arm with different requirements, allowing fast fabrication, prototyping, and assembly, and comprising joint and link sections that can be incorporated together to form an arm with an adjustable number of joints. An analytical approach was used to model the different bending angles at diverse pressures, and a data-driven approach was used to model the angular position with respect to the pressure. Forward and inverse kinematics were performed to calculate the orientation, position, and joint angle of each component. The results showed that the maximum bending angles for each corresponding joint were generally larger for joints number one and three but smaller for joint number two. Moreover, motion analysis data showed that each joint exhibited different bending patterns. Our bio-inspired arm design demonstrated that it could conduct diverse motions at various pressures, in contrast to the soft arms seen in the literature. Additionally, the modular construction of the arm allows it to access larger workplaces, and a gripper should be included in future versions to increase the arm’s capabilities.

Current state and future direction of quality improvement in pediatric neurosurgery: a survey of pediatric neurosurgeons.

Quality improvement (QI) is a methodology used to implement sustainable, meaningful change to improve patient outcomes. Given the complex pathologies observed in pediatric neurosurgery, QI projects could potentially improve patient care. Overall, there is a need to characterize the degree of QI opportunities, training, and initiatives within the field of pediatric neurosurgery. Herein the authors aimed to define the current QI landscape in pediatric neurosurgery. A cross-sectional survey was sent to all members of the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Section on Pediatric Neurological Surgery via email. The responses were anonymized. Questions addressed several relatable QI topics including 1) training and participation in QI; 2) QI infrastructure; 3) QI program incentives; and 4) general opinions on the National Surgical Quality Improvement Program (NSQIP) database, various QI topics, and QI productivity. Responses were received from 129 participants (20% response rate). Most respondents practiced in an academic setting (59.8%) and at a free-standing pediatric hospital (65.4%). Participation in QI projects was high (81.7%), but only 23.8% of respondents had formal QI training. Only 36.5% of respondents had institutional requirements for QI work; the majority of those were only required to participate as a project team member. Nearly half of the respondents did not receive incentives or institutional support for QI. The majority agreed ("strongly" and "somewhat") that a QI course would be beneficial (75.5%), that QI projects should be considered for publication in neurosurgery journals (88.1%), and that there is a need for national quality metrics (81.4%). Over 88% have an interest in seeing QI project presentations at the annual Pediatric Joint Section meeting. Only 26.3% believed that the NSQIP was a useful QI guide. Respondents suggested further study of the following QI topics: overall rates of infection and their prevention, hydrocephalus, standardized treatment algorithms for common disorders, team communication, pediatric neurosurgery-specific database, access to care, and interprofessional education. Areas of opportunity include specialty-specific QI education, tactics for obtaining support to build the QI infrastructure, increased visibility of QI work within pediatric neurosurgery, and a review of available registries to provide readily available data relevant to this specialty.

A novel interfaces contact model for analyzing assembled joints of prefabricated underground structures

Modern prefabricated underground structures are the key advancement in the low-carbon urban construction. The rapid development of prefabricated structures has increased the diversity of assembled joints. It becomes more difficult to evaluate the joint performance considering multiple parameters, such as joint size, morphology, interface properties, and axial forces. Therefore, this study developed an assembled joints mechanical assessment model to solve the multi-parameter problems. First, the interface contact formulas were established for typical interfaces. Second, a joint interfaces contact model (JICM) was established based on the above formulas and multiple parameters. Finally, model validation and case study were performed for JICM. The results show that: (1) JICM fitted well with the experimental data, and reflected the multi-parameter effects of multi-type assembled joints. (2) JICM calculated the contact stress at the outer edge of the interfaces can be twice larger than the bending stress. Accordingly, JICM revealed the key reason for brittle damage of assembled joints. (3) JICM demonstrated promising joint design capabilities: it calculated that the bending moment contribution of one interfaces group was dominant; it further calculated the deformation and bearing capacity of the assembled joints at the yield and ultimate moments. (4) JICM demonstrated promising joint deformation control: it calculated the rotation developments of assembled joint and continuous section were not consistent; it further presented the deformation pattern of the assembled components was a folded line and can be 20% larger than that of a continuous component. JICM provides a tool for parametric design of joints and quantitatively evaluates multi-parameter effects, demonstrating practical value for urban green low-carbon construction.

Analytical solutions for vortex flow at the tangential inlet of a vertical dropshaft

Vertical dropshafts with tangential intake structures are often used in urban drainage systems to route surface flow into underground systems. Vortex flow driven by a tangential inlet is the typical flow pattern in the vertical dropshaft. However, analytical solutions of the key hydraulic transition from chute flow to vortex flow have not been investigated, and theoretical guidelines of the vortex dropshaft are not available. In the present study, a series of theoretical analytical solutions are proposed to determine the circumferential flow generated at the vertical dropshaft inlet. The contraction ratio of the tapering chute, dropshaft size, and flow depth at the joint section determines the vortex flow performance in the vertical dropshaft. Based on the free surface drop height, theoretical criteria are proposed to describe the spiral movement intensity in the vertical dropshaft. Systemic experiments for different vortex dropshaft models are tested, and the experimental observations agree with the theoretical analysis. The present investigation provides a general reference for a tangential dropshaft inlet design that can smoothly route rotational flow down a vertical dropshaft.

India’s Kolkata Section and Guwahati Subsection Inaugurate the IEEE PELS Joint Section Chapter

The IEEE Power Electronics Society (PELS) Joint Section Chapter of the Kolkata section and the Guwahati subsection was inaugurated on 21 September 2022 at the Electronics and Electrical Engineering Department, Indian Institute of Technology (IIT) Guwahati, India. The programme was held in hybrid mode. Prof. Sanjib Kumar Panda, an associate professor and area director of power and energy research at the Department of Electrical and Computer Engineering, National University of Singapore, also the coordinator, IEEE PELS Asia Pacific Region (R10) inaugurated the new Chapter. Chair of the IEEE Guwahati subsection, Prof. Sukumar Nandi, a professor of computer science engineering at IIT Guwahati was also present to grace the occasion. The inauguration ceremony was attended by approximately total 60 persons including faculty and student members (the photo was taken after the inauguration as shown in <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1</xref> ). Prof. Panda explained in details about the organization of IEEE and the Power Electronics Society, and its various activities and programmes. He specifically explained benefits of joining IEEE and PELS membership to student members.

Study on the Effect of Finger Joints on the Stiffness of Fibre-Managed E. nitens Sawn Boards

Fibre-managed E. nitens has the potential to be used as a feedstock for engineered wood products. This resource, however, has a number of strength-reducing features that need to be removed, and the board needs to be re-joint to be useful in greater lengths for timber construction. A common jointing practice is finger jointing. The suitability of the finger jointing technique for this species is crucial to the mechanical properties of the final product. This study was conducted to explore the influence of finger jointing on the stiffness of sawn boards. A strict manufacturing process of docking and re-joining timber boards in the same location without removing strength-reducing features was conducted to compare the stiffness parameters before and after finger jointing with bending tests. A statistical analysis was conducted. The results showed that the frequency of finger joints along the board did not significantly impact the edgewise stiffness; however, the average flatwise stiffness of the samples with more finger joints was improved slightly. A 10% increase in the end pressure reduced the tip gap significantly but did not influence the stiffness. The finger joint efficiency was 0.824 for the edgewise stiffness of the samples and 1.034 for flatwise stiffness of the jointed sections.

In Memoriam: Hamit Ziya Gökalp, 1929 to 2022.

In Memoriam: Hamit Ziya Gökalp, 1929 to 2022.

Effects of different design factors on the shear performance of assembled steel–concrete composite beam with local laminated joint

This paper aims to experimentally investigate the effects of constructional details on the shear resistance of assembled steel–concrete composite beam with the local laminated joint. A series of push-out experiments were carried out to clarify the key structural factors determining the shear behavior and failure mechanism of post-cast wet joints under the combined action of the longitudinal loading and bending loading. Results indicated that the anchorage length of bottom transverse reinforcement placed in the post-pouring region had a significant impact on the shear resistance of assembled concrete slab, especially the ultimate bearing capacity and ductility of push-out specimens decreased when the anchorage length decreased to a critical value. In addition, using the U-type bottom transverse reinforcement could optimize the size of reserved slots, but this method presented a poor performance in limiting the cracking and failure behaviors of assembled slabs. Compared with the surface roughness treatment of the prefabricated concrete slab, the steel bar truss applied in the local laminated part could effectively strengthen the interface bond strength between the precast concrete and post-cast concrete, avoiding the premature cracking phenomenon. Furthermore, the reasonable layout of bottom transverse reinforcements could make full use of the plastic properties of steel bars and increase the shear resistance of assembled concrete slab, but the plastic deformation of steel bars might lead to the crushing of the post-cast concrete near the interface between the precast concrete and post-cast concrete. Finally, discussing the change of stress distribution on the section of post-cast wet joints caused by the negative bending moment based on the failure analyses, and the formulas of the shear capacity of local laminated joints considering the effects of the negative moment and constructional details were established.

Daphnoretin relieves IL-1β-mediated chondrocytes apoptosis via repressing endoplasmic reticulum stress and NLRP3 inflammasome

BackgroundOsteoarthritis (OA), mainly caused by severe joint degeneration, is often accompanied by joint pain and dysfunction syndrome. Inflammatory mediators and apoptosis play key roles in the evolution of OA. It is reported that daphnoretin has significant antiviral and anti-tumor values. The present study aims at investigating the role of daphnoretin in OA.MethodsThe OA mouse model was constructed by performing the destabilization of the medial meniscus through surgery, and the OA cell model was induced in ATDC5 chondrocytes with IL-1β (10 ng/mL) in vitro. Chondrocyte viability and apoptosis were measured by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT), Caspase-3 activity, and flow cytometry. The levels of COX-2, iNOS, TNF-α, IL-6, Bax, Bcl2, cleaved-Caspase3, endoplasmic reticulum stress (ERS) proteins (GRP78, CHOP, ATF6, and Caspase-12), and NLRP3-ASC-Caspase1 inflammasome were determined by quantitative real-time PCR or western blot. The concentrations of TNF-α, IL-6, and PGE2 were tested by enzyme-linked immunosorbent assay. The content of nitrates was detected by the Griess method. In vivo, morphologic differences in knee joint sections and the thickness of the subchondral bone density plate in mice were observed by hematoxylin–eosin (H&E) staining and safranin O-fast green staining.ResultsDaphnoretin effectively choked IL-1β-induced chondrocyte apoptosis and facilitated cell viability. Daphnoretin dose-dependently abated ERS, inflammatory mediators, and the activation of NLRP3 inflammasomes in IL-1β-induced chondrocytes. What’s more, in vivo experiments confirmed that daphnoretin alleviated OA progression in a murine OA model by mitigating inflammation and ERS.ConclusionDaphnoretin alleviated IL-1β-induced chondrocyte apoptosis by hindering ERS and NLRP3 inflammasome.Graphical abstract