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.
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.
Objective
The aim of this study was to compare the radiological features of intravertebral clefts (IVC) between Kümmell disease (KD) and acute osteoporotic vertebral compression fracture (OVCF).
...Materials and Methods
This is a retrospective study. A total of 79 patients with IVC from January 2014 to December 2018 were included in this study. There were 22 men and 57 women, with an average of 73.5 years. Based on the exact time interval from injury to treatment and the pathological examination results, the patients were divided into KD group (44 patients) and acute OVCF group (35 patients). The two groups were compared by the margin sclerosis of IVC, vertebra and pedicle ossification, stress fracture of the spinous process, paravertebral callus, the shape of IVC, cleft in the adjacent disc, and flatness of IVC's margin from plain radiographs and computed tomography (CT). The two groups were compared by the IVC content, double‐line sign, and signal of fracture vertebral from their magnetic resonance imaging (MRI).
Results
There were no significant differences in sex, age, and fracture distribution between the KD group and the acute OVCF group. IVC was present in both the KD group and the acute OVCF group. Six radiological features were only present in the KD group, including sclerosis of the cleft margin (95.5%, 42/44), ossification of the fractured vertebrae (100%, 44/44), ossification of the pedicle (31.8%, 14/44), double‐line sign (27.3%, 12/44), stress fracture of the spinous process (13.6%, 6/44), and even formation of paravertebral callus (18.2%, 8/44). Although there were statistical differences in the other four radiological features of content of IVC (P = 0.02), cleft sign in adjacent intervertebral disc (P < 0.01), margin of IVC (P = 0.02), and the shape of IVC (P = 0.01) between the KD group and acute OVCF group, these characteristics could be found in both groups.
Conclusion
IVC could present in patients with both KD and acute OVCF; however, we found that marginal cleft sclerosis, vertebral and pedicle ossification, double‐line sign, spinous process fracture, and formation of paravertebral callus are unique radiological features of KD and could be used for differentiation of KD from acute OVCF with IVC.
Intravertebral clefts (IVC) could present in patients with both Kümmell disease (KD) and acute osteoporotic vertebral compression fractures (OVCF), which leads to challenges in the differentiation of clinical diagnosis. We found that there were some imaging features that were unique to KD (Fig. 1) but not in acute OVCF (Fig. 2).
There is a constant concentration zone for acetone‐water mixtures, and the average relative volatility of the two components in the constant concentration zone is only 1.41, so the energy consumption ...of the conventional distillation process is high. Two kinds of split mechanical vapor recompression (MVR) heat pump distillation processes, i.e., single‐stage and two‐stage compression processes, were proposed to separate acetone‐water mixtures. The thermodynamic data of the mixture were calculated and modules of Aspen Plus were used to simulate the distillation column and steam compressor. Taking the minimum total annual cost as the objective function, the conventional MVR and the two split MVR heat pump distillation processes were simulated and optimized. Compared with the conventional process, the MVR heat pump distillation process had greater economic advantages, and the split heat pump distillation (SHPD) with two‐stage compression was superior to the other MVR heat pump distillation processes.
Split mechanical vapor recompression heat pump distillation for acetone‐water mixtures with constant concentration zone is investigated. Four different distillation processes were simulated and discussed. The proposed process had greater economic advantages than the conventional distillation process, so an effective energy‐saving approach for separating acetone and water is introduced.
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