Conducting research on the fatigue performance of concrete materials is of great significance for the anti fatigue design of concrete structures. Currently, indirect tensile or compressive strength ...tests are commonly used to study the fatigue performance of basalt fiber reinforced concrete, but there is little research on its fatigue performance under direct tensile conditions. Using a fatigue testing machine and a self-developed concrete axial tensile device, direct tensile fatigue tests of basalt fiber reinforced concrete were conducted under different fiber content and stress levels. Based on fatigue test data, the entire fatigue tensile process of basalt fiber reinforced concrete was analyzed, and the effects of fiber content and stress level on the fatigue life of concrete specimens were explored. Strain fatigue life curves of concrete with different fiber content were plotted. The experimental results indicate that the failure mode of basalt fiber reinforced concrete under cyclic loading is brittle failure; with the increase of basalt fiber content, the fatigue life of concrete first increases and then decreases. When the fiber content is 0.3%, the fatigue life of basalt fiber concrete is the highest compared to the benchmark concrete. When the fiber content is the same, the fatigue life of concrete decreases with the increase of stress level. The fatigue deformation process of basalt fiber reinforced concrete can be divided into three stages: the stage of fast strain growth, the stage of uniform strain growth, and the stage of rapid strain growth.
Abstract
In order to study the axial tensile properties of polypropylene fiber reinforced concrete, an axial tensile test device for concrete is developed in this paper. The device is composed of ...three parts: rigid frame, spherical hinge and puller, and specimen fabrication part. The test device can accurately measure the tensile strength and peak tensile strain of concrete, and perfectly solves the eccentricity problem of concrete specimens under tension. It can measure the post peak segment tensile strain, such that the whole process tensile stress–strain curve can be obtained. The axial tensile test of polypropylene fiber concrete was carried out using the above test device, and the results show that the tensile strength of concrete can be clearly improved by adding polypropylene fiber, which makes the tensile failure of concrete show certain plastic characteristics. The test results show that with the increase in fiber content, the tensile strength of concrete increases first and then decreases. The effects of polypropylene fiber content and curing age on the tensile properties of concrete were studied and the optimum polypropylene fiber content was determined. When the fiber content is 0.9 kg/m
3
, the tensile strength of concrete reaches the maximum value. The splitting tensile test of concrete under the same condition was carried out simultaneously. The damage phenomenon and test results of the axial tensile test and splitting tensile test of concrete were compared and analyzed, and the applicability of the new developed device in the concrete axial tensile test was verified.
Osteoarthritis (OA) is a complicated joint disorder characterized by inflammation that causes joint destruction. Cucurbitacin B (CuB) is a naturally occurring triterpenoid compound derived from ...plants in the Cucurbitaceae family. The aim of this study is to investigate the potential role and mechanisms of CuB in a mouse model of OA. This study identified the key targets and potential pathways of CuB through network pharmacology analysis. In vivo and in vitro studies confirmed the potential mechanisms of CuB in OA. Through network pharmacology, 54 potential targets for CuB in treating OA were identified. The therapeutic potential of CuB is associated with the nod‐like receptor pyrin domain 3 (NLRP3) inflammasome and pyroptosis. Molecular docking results indicate a strong binding affinity of CuB to nuclear factor erythroid 2‐related factor 2 (Nrf2) and p65. In vitro experiments demonstrate that CuB effectively inhibits the expression of pro‐inflammatory factors induced by interleukin‐1β (IL‐1β), including cyclooxygenase‐2, inducible nitric oxide synthase, IL‐1β, and IL‐18. CuB inhibits the degradation of type II collagen and aggrecan in the extracellular matrix (ECM), as well as the expression of matrix metalloproteinase‐13 and a disintegrin and metalloproteinase with thrombospondin motifs‐5. CuB protects cells by activating the Nrf2/hemeoxygenase‐1 (HO‐1) pathway and inhibiting nuclear factor‐κB (NF‐κB)/NLRP3 inflammasome‐mediated pyroptosis. Moreover, in vivo experiments show that CuB can slow down cartilage degradation in an OA mouse model. CuB effectively prevents the progression of OA by inhibiting inflammation in chondrocytes and ECM degradation. This action is further mediated through the activation of the Nrf2/HO‐1 pathway to inhibit NF‐κB/NLRP3 inflammasome activation. Thus, CuB is a potential therapeutic agent for OA.
Abstract
Background
Steroid-induced avascular necrosis of the femoral head (SANFH) is characterized by osteoblast apoptosis, leading to a loss of bone structure and impaired hip joint function. It ...has been demonstrated that erythropoietin (EPO) performs a number of biological roles.
Objective
We examined the effects of EPO on SANFH and its regulation of the STAT1-caspase 3 signaling pathway.
Method
In vitro, osteoblasts were treated with dexamethasone (Dex) or EPO. We identified the cytotoxicity of EPO by CCK-8, the protein expression of P-STAT1, cleaved-caspase9, cleaved-caspase3, Bcl-2, BAX, and cytochrome c by Western blotting, and evaluated the apoptosis of osteoblasts by flow cytometry. In vivo, we analyzed the protective effect of EPO against SANFH by hematoxylin and eosin (H&E), Immunohistochemical staining, and Micro-computed tomography (CT).
Results
In vitro, EPO had no apparent toxic effect on osteoblasts. In Dex-stimulated cells, EPO therapy lowered the protein expression of BAX, cytochrome c, p-STAT1, cleaved-caspase9, and cleaved-caspase3 while increasing the expression of Bcl-2. EPO can alleviate the apoptosis induced by Dex. In vivo, EPO can lower the percentage of empty bone lacunae in SANFH rats.
Conclusion
The present study shows that EPO conferred beneficial effects in rats with SANFH by inhibiting STAT1-caspase 3 signaling, suggesting that EPO may be developed as a treatment for SANFH.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study, the hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation (DPD) with the compression axis taken at different angles to the sheet normal direction (ND). {10-12} ...twin variant selected is not always the primary one with the highest Schmid factor (SF). For some twinned grains in which the orientations have a deviation of about 10°–40° from the ideal orientation (i.e. rolling direction) favoring {10-12} twinning under compression loading to the DPD direction, the nucleated twin variants have the highest SFs; with higher deviation of 30°–60°, the first twins to form are low-SF variants in the twinned grains. This non-Schmid effect is probably associated with the local-stress fluctuation near grain boundary due to strain accommodation between grains. And the deviation angle that ranged from 30° to 40° is considered to be a transition of variant selection toward the non-Schmid behavior.
•Some {10–12} twinning behaviors are not following the Schmid law.•A high deviation of grain orientation from ND results in the non-Schmid twinning behavior.•There is a transition region of {10–12} twinning nucleation toward the non-Schmid behavior.
The present work was devoted to explore the quantitative structure‐property relationships for gas‐to‐ionic liquid partition coefficients (log KILA). A series of linear models were first established ...for the representative dataset (IL01). The optimal model was a four‐parameter equation (1Ed) consisting of two electrostatic potential‐based descriptors (
ΣVs,ind-
${{\rm { \Sigma }}{V}_{s,ind}^{-}}$
and Vs,max), one 2D matrix‐based descriptor (J_D/Dt) and dipole moment (μ). All of the four descriptors introduced in the model can find the corresponding parameters, directly or indirectly, from Abraham's linear solvation energy relationship (LSER) or its theoretical alternatives, which endows the model good interpretability. Gaussian process was utilized to build the nonlinear model. Systematical validations, including 5‐fold cross‐validation for the training set, the validation for test set, as well as a more rigorous Monte Carlo cross‐validation were performed to verify the reliability of the constructed models. Applicability domain of the model was evaluated, and the Williams plot revealed that the model can be used to predict the log KILA values of structurally diverse solutes. The other 13 datasets were also processed in the same way, and all of the linear models with expressions similar to equation 1Ed were obtained. These models, whether linear of nonlinear, represent satisfactory statistical results, which confirms the universality of the method adopted in this study in QSPR modeling of gas‐to‐IL partition.
•The main determinants for depression after lacunar and non-lacunar stroke were different.•Infarctions in the frontal cortex were significantly associated with post-stroke depression.•For patients of ...lacunar stroke, the location of the infarction was not associated with the presence of post-stroke depression.
Depression is common after both lacunar stroke and non-lacunar stroke and might be associated with lesion locations as proven by some studies. This study aimed to identify whether lesion location was critical for depression after both lacunar and non-lacunar strokes.
A cohort of ischemic stroke patients was assigned to either a lacunar stroke group or a non-lacunar stroke group after a brain MRI scan. Neurological deficits and treatment response was evaluated during hospitalization. The occurrence of depression was evaluated 3 months later. Logistic regressions were used to identify the independent risk factors for depression after lacunar and non-lacunar stroke respectively.
83 of 246 patients with lacunar stroke and 71 of 185 patients with non-lacunar stroke developed depression. Infarctions in the frontal cortex, severe neurological deficits, and a high degree of handicap were identified as the independent risk factors for depression after non-lacunar stroke, while lesion location was not associated with depression after lacunar stroke.
The main determinants for depression after lacunar and non-lacunar stroke were different. Lesion location was critical only for depression after non-lacunar stroke.
Lattice structures with excellent mechanical performance can be achieved through delicate design. In this work, inspired by the soft–hard multiphase crystals, three types of dual phase lattice ...structures (DPLS) composed of body-centered cubic with Z-struts (BCCZ) matrix phase and face and body-centered cubic with Z-struts (FBCCZ) reinforcement phase were designed and fabricated by selective laser melting (SLM) using 316L stainless steel powder. Quasi-static compression experiment and numerical simulation were carried out to investigate their mechanical properties, energy absorption and deformation behavior. The results showed that the mechanical properties of all DPLS samples were higher than that of single phase BCCZ lattice structure. The four-body diagonal DPLS sample exhibited the highest specific strength and specific stiffness, which was 9.0% and 14.2% higher than single phase BCCZ lattice structure; while, the two-face diagonal DPLS sample had the highest specific energy absorption value of 17.45 J/g. Besides, the experimental and simulated results revealed that the arrangements and volume fraction of reinforcement phase had a significant impact on the performance, deformation behavior and internal stress distribution of the DPLS samples during compressive deformation.
Graphical Abstract
Glucocorticoid‐induced osteonecrosis of the femoral head (GIONFH) is the main complication secondary to long‐term or excessive use of glucocorticoids (GCs). Taxifolin (TAX) is a natural antioxidant ...with various pharmacological effects, such as antioxidative stress and antiapoptotic properties. The purpose of this study was to explore whether TAX could regulate oxidative stress and apoptosis in GIONFH by activating the nuclear factor erythroid 2‐related factor 2 (Nrf2) pathway. We conducted qRT‐PCR, Western blotting, TUNEL assays, flow cytometry, and other experiments in vitro. Microcomputed tomography analysis, hematoxylin–eosin staining, and immunohistochemical staining were performed to determine the therapeutic effect of TAX in vivo. TAX mitigated the overexpression of ROS and NOX gene expression induced by DEX, effectively reducing oxidative stress. Additionally, TAX could alleviate DEX‐induced osteoblast apoptosis, as evidenced by qRT‐PCR, Western blotting, and other experimental techniques. Our in vivo studies further demonstrated that TAX mitigates the progression of GIONFH in rats by combating oxidative stress and apoptosis. Mechanistic exploration revealed that TAX thwarts the progression of GIONFH through the activation of the Nrf2 pathway. Overall, our research herein reports that TAX‐mediated Nrf2 activation ameliorates oxidative stress and apoptosis for the treatment of GIONFH.
