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STS loaded PCL-MECM based hydrogel hybrid scaffold seeded with MFCs could achieve good meniscus regeneration and chondroprotective effects in the rabbit.

The influences of the environmentally friendly sealing processes of cerium salt sealing and hydrothermal sealing on the electrochemical behavior of the anodic oxide film of an aluminum alloy were examined by accelerated corrosion of dry-wet alternate immersion corrosion tests, combined with the morphologies observation, chemical composition tests, and electrochemical tests. A severe corrosion environment with high temperature, high humidity, and high salt spray was adopted. The results of electrochemical characteristics show that cerium salt sealing affected the inner barrier layer of the film instead of the outer porous film. The higher impedance of the inner barrier layer is related to the reaction between cerium ions and cathodic reaction products of hydroxyl ions. Hydrothermal sealing, although had some good influence on both the porous layer and the barrier layer of the oxide film, corrosion inhibition on the whole cannot do better than that of cerium salt sealing in the early days. However, as the corrosion time went on, the hydrothermal sealing sample showed better durability.

Intervertebral disc degeneration (IDD) is the leading cause of low back pain (LBP). However, effective therapeutic drugs for IDD remain to be further explored. Inflammatory cytokines play a pivotal role in the onset and progression of IDD. Dihydroartemisinin (DHA) has been well reported to have powerful anti-inflammatory effects, but whether DHA could ameliorate the development of IDD remained unclear. In this study, the effects of DHA on extracellular matrix (ECM) metabolism and cellular senescence were firstly investigated in nucleus pulposus cells (NPCs) under tumor necrosis factor alpha (TNFα)-induced inflammation. Meanwhile, AKT agonist sc-79 was used to determine whether DHA exerted its actions through regulating PI3K/AKT and NF-κB signaling pathways. Next, the therapeutic effects of DHA were tested in a puncture-induced rat IDD model. Finally, we detected the activation of PI3K/AKT and NF-κB signaling pathways in clinical degenerative nucleus pulposus specimens. We demonstrated that DHA ameliorated the imbalance between anabolism and catabolism of extracellular matrix and alleviated NPCs senescence induced by TNFα in vitro. Further, we illustrated that DHA mitigated the IDD progression in a puncture-induced rat model. Mechanistically, DHA inhibited the activation of PI3K/AKT and NF-κB signaling pathways induced by TNFα, which was undermined by AKT agonist sc-79. Molecular docking predicted that DHA bound to the PI3K directly. Intriguingly, we also verified the activation of PI3K/AKT and NF-κB signaling pathways in clinical degenerative nucleus pulposus specimens, suggesting that DHA may qualify itself as a promising drug for mitigating IDD.

Clinically, microfracture is the most commonly applied surgical technique for cartilage defects. However, an increasing number of studies have shown that the clinical improvement remains questionable, and the reason remains unclear. Notably, recent discoveries revealed that signals from regenerated niches play a critical role in determining mesenchymal stem cell fate specification and differentiation. We speculate that a microenvironmentally optimized scaffold that directs mesenchymal stem cell fate will be a good therapeutic strategy for cartilage repair. Therefore, we first explored the deficiency of microfractures in cartilage repair. The microfracture not only induced inflammatory cell aggregation in blood clots but also consisted of loose granulation tissue with increased levels of proteins related to fibrogenesis. We then fabricated a functional cartilage scaffold using two strong bioactive cues, transforming growth factor-β3 and decellularized cartilage extracellular matrix, to modulate the cell fate of mesenchymal stem cells. Additionally, poly(ε-caprolactone) was also coprinted with extracellular matrix-based bioinks to provide early mechanical support. The in vitro studies showed that microenvironmentally optimized scaffolds exert powerful effects on modulating the mesenchymal stem cell fate, such as promoting cell migration, proliferation and chondrogenesis. Importantly, this strategy achieved superior regeneration in sheep via scaffolds with biomechanics (restored well-organized collagen orientation) and antiapoptotic properties (cell death-related genes were also downregulated). In summary, this study provides evidence that microenvironmentally optimized scaffolds improve cartilage regeneration in situ by regulating the microenvironment and support further translation in human cartilage repair. STATEMENT OF SIGNIFICANCE: Although microfracture (MF)-based treatment for chondral defects has been commonly used, critical gaps exist in understanding the biochemistry of MF-induced repaired tissue. More importantly, the clinically unsatisfactory effects of MF treatment have prompted researchers to focus on tissue engineering scaffolds that may have sufficient therapeutic efficacy. In this manuscript, a 3D printing ink containing cartilage tissue-specific extracellular matrix (ECM), methacrylate gelatin (GelMA), and transforming growth factor-β3 (TGF-β3)-embedded polylactic-coglycolic acid (PLGA) microspheres was coprinted with poly(ε-caprolactone) (PCL) to fabricate tissue engineering scaffolds for chondral defect repair. The sustained release of TGF-β3 from scaffolds successfully directed endogenous stem/progenitor cell migration and differentiation. This microenvironmentally optimized scaffold produced improved tissue repair outcomes in the sheep animal model, explicitly guiding more organized neotissue formation and therefore recapitulating the anisotropic structure of native articular cartilage. We hypothesized that the cell-free scaffolds might improve the clinical applicability and become a new therapeutic option for chondral defect repair.

Electrical fire accidents occurred frequently all over the world in recent years, which had caused a large number of casualties and property losses. The main cause of electrical fire is electrical wire short circuit fault. Investigations of the characteristic and influence factors of the molten marks play an important role to determine the cause of fire. In the present work, microscopic characteristics of copper wires with short-circuit molten marks in electrical fire were investigated. Primary and secondary short-circuit molten marks (PMMs and SMMs) of copper wires were prepared by simulation test. The micro-morphology, microstructure and chemical composition of molten marks were observed and compared. Based on the quantitative characterization, effects of different overload currents and heating temperatures on the microstructure of molten marks were analyzed. The results would provide fundamental information for cause identification of the electrical fire.

Three-dimensional printing (3DP) is a popular manufacturing technique with versatile potential for materials processing in tissue engineering and regenerative medicine. In particular, the repair and regeneration of significant bone defects remain as substantial clinical challenges that require biomaterial implants to maintain mechanical strength and porosity, which may be realized using 3DP. The rapid progress in 3DP development in the past decade warrants a bibliometric analysis to gain insights into its applications in bone tissue engineering (BTE). Here, we performed a comparative study using bibliometric methods for 3DP in bone repair and regeneration. A total of 2,025 articles were included, and the results showed an increase in the number of publications and relative research interest on 3DP annually worldwide. China was the leader in international cooperation in this field and also the largest contributor to the number of citations. The majority of articles in this field were published in the journal Biofabrication. Chen Y was the author who made the highest contribution to the included studies. The keywords included in the publications were mainly related to BTE and regenerative medicine (including “3DP techniques,” “3DP materials,” “bone regeneration strategies,” and “bone disease therapeutics”) for bone regeneration and repair. This bibliometric and visualized analysis provides significant insights into the historical development of 3DP in BTE from 2012 to 2022, which will be beneficial for scientists to conduct further investigations into this dynamic field.

Premature failure of headspan suspensions was mainly attributed to the fracture failure of the droppers. Various experiments were conducted to explore the fracture failure mechanism of the droppers used in headspan suspensions. Four notches along the axial direction of the dropper, corrosion pits and corrosion products were observed by visual examination. Although the axial cracks have little effect on the structural strength, they make it easier to form corrosion environment in the notches than on the exposed outer surfaces. Furthermore, energy spectrum analysis indicated the presence of chlorine and sulfur both in the corrosion products inside of axial cracks and corrosion pits. Meanwhile, typical microstructural features of intergranular cracking and corrosion products were observed by the scanning electron microscopy. Finally, finite element analysis was conducted to characterize the stress distribution near the corrosion pits. The simulation results showed that obvious stress concentration was formed near the corrosion area. All the results indicated that the droppers failed due to the combination of pitting corrosion and stress corrosion cracking.

Articular cartilage defect repair is a problem that has long plagued clinicians. Although mesenchymal stem cells (MSCs) have the potential to regenerate articular cartilage, they also have many limitations. Recent studies have found that MSC-derived exosomes (MSC-Exos) play an important role in tissue regeneration. The purpose of this study was to verify whether MSC-Exos can enhance the reparative effect of the acellular cartilage extracellular matrix (ACECM) scaffold and to explore the underlying mechanism. The results of in vitro experiments show that human umbilical cord Wharton's jelly MSC-Exos (hWJMSC-Exos) can promote the migration and proliferation of bone marrow-derived MSCs (BMSCs) and the proliferation of chondrocytes. We also found that hWJMSC-Exos can promote the polarization of macrophages toward the M2 phenotype. The results of a rabbit knee osteochondral defect repair model confirmed that hWJMSC-Exos can enhance the effect of the ACECM scaffold and promote osteochondral regeneration. We demonstrated that hWJMSC-Exos can regulate the microenvironment of the articular cavity using a rat knee joint osteochondral defect model. This effect was mainly manifested in promoting the polarization of macrophages toward the M2 phenotype and inhibiting the inflammatory response, which may be a promoting factor for osteochondral regeneration. In addition, microRNA (miRNA) sequencing confirmed that hWJMSC-Exos contain many miRNAs that can promote the regeneration of hyaline cartilage. We further clarified the role of hWJMSC-Exos in osteochondral regeneration through target gene prediction and pathway enrichment analysis. In summary, this study confirms that hWJMSC-Exos can enhance the effect of the ACECM scaffold and promote osteochondral regeneration., Graphical abstract Image 1, Highlights • hWJMSC-Exos can promote cell proliferation, migration and polarization in vitro. • hWJMSC-Exos can enhance the repair effect of ACECM scaffold in vivo. • hWJMSC-Exos can inhibit inflammation in the joint cavity. • hWJMSC-Exos contain a variety of miRNAs that promote osteochondral regeneration.

Spinel manganese-based oxide, as a promising cathode material for aqueous zinc-ion batteries (ZIBs), has attracted wide attention due to advantages of high voltage platform, and non-toxic and environmental friendliness. However, the poor conductivity and structural collapse due to the dissolution of Mn2+ limit the properties of the material. In this paper, the ZnMn2O4 nanoparticles with coating of Cu0-doped CuO (ZnMn2O4/CuO) were prepared by hydrothermal reaction and subsequent sintering process. The coating of Cu0-doped CuO displays a synergistic effect of two-phase composite, which effectively improves the conductivity and the charging/discharging electrochemical performance of the composite. As cathode materials for ZIBs, the ZnMn2O4/CuO composite shows a discharge-specific capacity of 150 mAh g−1 after an activation process at 300 mA g−1, it exhibits improved electrochemical performance than the pure ZnMn2O4. At a high current density of 2 A g−1, the composite displays a capacity of 118 mA h g−1, and the Coulomb efficiency of above 96% can be maintained throughout the cycles, indicating the high reversibility of charging and discharging.

The intergranular corrosion behavior of 6061 aluminum alloy welded joints produced by metal inert gas welding and friction stir welding was studied. The microstructure of the welded joints and the intergranular corrosion morphology of the cross-section were analyzed by optical microscopy. The results show that the most sensitive area of intergranular corrosion is the partially melted zone of the metal inert gas welding, and the maximum corrosion depth is about seven times that of the base metal, followed by the unmixed zone. The heat affected zone has the lowest sensitivity. Although the welding seam corroded seriously, general corrosion played a leading role. With the high heat input of metal inert gas welding, the sensitivity to intergranular corrosion in the partially melted zone increased significantly, while other zones had little change. For friction stir welding joints, the heat affected zone suffered from the most severe corrosion, and the nugget zone the least. However, the difference is not apparent. The susceptibility to intergranular corrosion of friction stir welding joints is weaker than that of metal inert gas welding joints but more severe than the base metal.

Tissue engineering provides a promising avenue for treating cartilage defects. However, great challenges remain in the development of structurally and functionally optimized scaffolds for cartilage repair and regeneration. In this study, decellularized cartilage extracellular matrix (ECM) and waterborne polyurethane (WPU) were employed to construct WPU and WPU-ECM scaffolds by water-based 3D printing using low-temperature deposition manufacturing (LDM) system, which combines rapid deposition manufacturing with phase separation techniques. The scaffolds successfully achieved hierarchical macro‐microporous structures. After adding ECM, WPU scaffolds were markedly optimized in terms of porosity, hydrophilia and bioactive components. Moreover, the optimized WPU-ECM scaffolds were found to be more suitable for cell distribution, adhesion, and proliferation than the WPU scaffolds. Most importantly, the WPU-ECM scaffold could facilitate the production of glycosaminoglycan (GAG) and collagen and the upregulation of cartilage-specific genes. These results indicated that the WPU-ECM scaffold with hierarchical macro‐microporous structures could recreate a favorable microenvironment for cell adhesion, proliferation, differentiation, and ECM production. In vivo studies further revealed that the hierarchical macro‐microporous WPU-ECM scaffold combined with the microfracture procedure successfully regenerated hyaline cartilage in a rabbit model. Six months after implantation, the repaired cartilage showed a similar histological structure and mechanical performance to that of normal cartilage. In conclusion, the hierarchical macro‐microporous WPU-ECM scaffold may be a promising candidate for cartilage tissue engineering applications in the future.

The regulation of fibrotic activities is key to improving pathological remodelling post-myocardial infarction (MI). Currently, in the clinic, safe and curative therapies for cardiac fibrosis and improvement of the pathological fibrotic environment, scar formation and pathological remodelling post-MI are lacking. Previous studies have shown that miR-486 is involved in the regulation of fibrosis. However, it is still unclear how miR-486 functions in post-MI regeneration. Here, we first demonstrated that miR-486 targeting SRSF3/p21 mediates the senescence of cardiac myofibroblasts to improve their fibrotic activity, which benefits the regeneration of MI by limiting scar size and post-MI remodelling. miR-486-targeted silencing has high potential as a novel target to improve fibrotic activity, cardiac fibrosis and pathological remodelling.

The maintenance of bone homeostasis includes both bone resorption by osteoclasts and bone formation by osteoblasts. These two processes are in dynamic balance to maintain a constant amount of bone for accomplishing its critical functions in daily life. Multiple cell type communications are involved in these two complex and continuous processes. In recent decades, an increasing number of studies have shown that osteogenic and osteoclastic extracellular vesicles play crucial roles in regulating bone homeostasis through paracrine, autosecretory and endocrine signaling. Elucidating the functional roles of extracellular vesicles in the maintenance of bone homeostasis may contribute to the design of new strategies for bone regeneration. Hence, we review the recent understandings of the classification, production process, extraction methods, structure, contents, functions and applications of extracellular vesicles in bone homeostasis. We highlight the contents of various bone-derived extracellular vesicles and their interactions with different cells in the bone microenvironment during bone homeostasis. We also summarize the recent advances in EV-loaded biomaterial scaffolds for bone regeneration and repair.

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The influence of metal inert-gas arc welding (MIG) on the corrosion behavior of 6061-T6 aluminum alloy in a simulated tropical marine atmospheric environment (related to high temperature, high humidity and high salt spray) were examined by dry-wet alternate immersion corrosion tests. The equivalent conversion was used to design the accelerated test time. The results show that in the initial stage, the intermetallic compound, rich in Fe, Si and Cu, had little influence on corrosion resistance in the heat-affected zone. For a corrosion time of 3 days in a tropical marine atmospheric environment, the corrosion rate of the welded joint increased rapidly, even reaching 3.5 times that of the base metal. Though the corrosion products had significant impact on slowing down the corrosion rate, as with the base metal, the corrosion rate of the welded joint was nearly double that of the base metal during the longest cycle period involving alternate immersion corrosion tests for 20 days.

Pitting corrosion of 2Cr13 stainless steel was investigated by deep-sea exposure test at various depths of 500 m, 800 m and 1200 m in the South China Sea for 4 months. With the aid of electrochemical measurements in simulated deep-sea environments and grey relational analysis, the influence of deep-sea environments on passive film and the mechanism of pitting corrosion were discussed. The results indicated that with the increase of sea depth, pitting depth of 2Cr13 stainless steel increased, which can be attributed to the change of chemical composition and the degradation of pitting resistance of passive film. Film growth was greatly retarded in the condition of low seawater temperature and low dissolved oxygen content of deep sea, resulting in an unstable and vulnerable film. Pitting depth was most influenced by hydrostatic pressure, which can increase the adsorption and penetration of Cl− ion, and promote the proliferation of point defects in passive film, leading to rapid deconstruction of protective oxides of the film. Pitting sensitivity of 2Cr13 stainless steel increased eventually with the combination of accelerated dissolution and suppressed self-healing of passive film in deep sea.

The serial-type deep-sea environmental test device was used to investigate the corrosion behaviour of 1060 aluminium exposed at real sea for 0.5 year and 2 years. Specimens were deployed at a depth...

In this work, a commercial extruded Mg-6Zn-0.5Zr (ZK60) magnesium alloy was compressed to investigate the correlations among flow curve shape, microstructure evolution and loading parameters in terms of strain rate and deformation temperature. According to the results, twinning played an important role during deformations below 250 °C and the number of twinning bands increased with the increase in strain rate. Twinning caused initially softening followed by hardening. The flow curve shape before peak stress was determined by the number of twinning bands that were initiated. Dynamic recrystallization (DRX) was initiated during deformations at temperatures higher than 150 °C, and the DRX grain size decreased with strain rate and increased with deformation temperature. At 400 °C, twinning was not initiated and the microstructure of the specimens was composed of both DRX and SRX (static recrystallization) grains.

In situ muon spin relaxation is demonstrated as an emerging technique that can provide a volume-averaged local probe of the ionic diffusion processes occurring within electrochemical energy storage devices as a function of state of charge. Herein, we present work on the conceptually interesting NASICON-type all-solid-state battery LiM2(PO4)3, using M = Ti in the cathode, M = Zr in the electrolyte, and a Li metal anode. The pristine materials are studied individually and found to possess low ionic hopping activation energies of ∼50-60 meV and competitive Li+ self-diffusion coefficients of ∼10-10-10-9 cm2 s-1 at 336 K. Lattice matching of the cathode and electrolyte crystal structures is employed for the all-solid-state battery to enhance Li+ diffusion between the components in an attempt to minimize interfacial resistance. The cell is examined by in situ muon spin relaxation, providing the first example of such ionic diffusion measurements. This technique presents an opportunity to the materials community to observe intrinsic ionic dynamics and electrochemical behavior simultaneously in a nondestructive manner.

Batch of dropper wires in the power supply system of a subway line fractured in the past several years. The dropper wires are made of soft stainless steel wire (Grade 304) with a diameter of 3.0 mm. The subway line in which the dropper wires often fractured is built near the sea. In this work, failure mechanism of the fractured dropper wires was explored based on the macro- and micro-examinations. Several technologies including scanning electron microscopy and energy-dispersive x-ray spectroscopy were utilized to reveal the mechanism. The failure mechanism of the dropper wires is considered as fatigue fracture. Its chemical composition and mechanical properties meet the standard of 304 stainless steel. The microstructure of the failed dropper wires is normal. Influence of the corrosive environment promotes the initiation of the fatigue cracks.

In this work, GdMnO3 material is successfully prepared using sol-gel method and GdMn2O5/GdMnO3 materials are in-situ generated by acid treatment. These materials are investigated and applied as catalysts for oxygenated VOC complete oxidation. The evaluation results show that GdMn2O5/GdMnO3-1.00 exhibits a remarkable increase in catalytic activity (T50% = 198 °C and T90% = 225 °C) of 2-ethoxyethanol oxidation when compared with the initial sample GdMnO3 (T50% = 223 °C and T90% = none). Characterization analyses show that acid treatment can result in the significant improvement of specific surface area from 20.502 m2·g−1 to 67.952 m2·g−1, abundant surface Mn4+ content and active oxygen, excellent reducibility at low temperature in GdMn2O5/GdMnO3-1.00 sample. In-situ DRIFTS results point out that the main functional groups such as νas(OCO), νas(COO), νs(C O) are formed in the process of 2-ethoxyethanol oxidation over GdMn2O5/GdMnO3-1.00 sample and some by-products including ethanol, 2-ethoxyethyl acetate, acetic acid, carbonic acid, 2-ethoxyethyl 2-methoxyethyl ester, ethane and 1,1′-oxybis[2-methoxy-] can be produced at a reaction temperature of 200 °C. Additionally, in-situ DRIFTS studies indicate the presence of gas-phase O2 plays a vital role in facilitating 2-ethoxyethanol deep oxidation to final products.

Background The dedifferentiation of chondrocytes and the unstable chondrogenic differentiation status of pluripotent mesenchymal stem cells (MSCs) are immense issues in cell-based articular cartilage repair and regenerative strategies. Here, to improve the cartilage characteristics of seed cells, a double biomimetic acellular cartilage extracellular matrix (ACECM)-oriented scaffold was used to mimic the cartilage microenvironment for human umbilical cord Wharton’s jelly-derived MSCs (hWJMSCs) and primary cartilage cells (pACs) to regenerate hyaline cartilage. Methods A double biomimetic ACECM-oriented scaffold was created from the cartilage extracellular matrix of pig articular cartilage using pulverization decellularization freeze-drying procedures. hWJMSCs and pACs were co-cultured at ratios of 50:50 (co-culture group, ACCC), 0:100 (ACAC group) and 100:0 (ACWJ group) in the ACECM-oriented scaffold, and the co-culture system was implanted in a caprine model for 6 months or 9 months to repair full-thickness articular cartilage defects. The control groups, which had no cells, comprised the blank control (BC) group and the ACECM-oriented scaffold (AC) group. Gross morphology and magnetic resonance imaging (MRI) as well as histological and biomechanical evaluations were used to characterize the cartilage of the repair area. Results Relative to the control groups, both the gross morphology and histological staining results demonstrated that the neotissue of the ACCC group was more similar to native cartilage and better integrated with the surrounding tissue. Measurements of glycosaminoglycan content and Young’s modulus showed that the repair areas had more abundant cartilage-specific content and significantly higher mechanical strength in the ACCC group than in the control groups, especially at 9 months. On MRI, the T2-weighted signal of the repair area was homogeneous, and the oedema signal disappeared almost completely in the ACCC group at 9 months. HLA-ABC immunofluorescence staining demonstrated that hWJMSCs participated in the repair and regeneration of articular cartilage and escaped surveillance and clearance by the caprine immune system. Conclusion The structure and components of double biomimetic ACECM-oriented scaffolds provided a cartilage-like microenvironment for co-cultured seed cells and enhanced the biomechanics and compositions of neotissue. This co-culture system has the potential to overcome the dedifferentiation of passage chondrocytes and the unstable chondrogenic differentiation status of MSCs.

To explore the extensive oxidative mechanism of syringaldehyde, vanillin, and p-hydroxybenzaldehyde during the alkaline wet oxidation process (AWOP), the yield of these aromatic aldehydes from AWOP at various temperatures and reaction times was studied. The results showed that the aromatic aldehydes could not be converted into the corresponding aromatic acids during the AWOP, and that the aromatic aldehyde was stable when subjected to the oxygen-free AWOP. However, as the reaction temperature increased or the number of methoxyl groups on the aromatic ring increased, the yield of aromatic aldehyde sharply decreased during the AWOP. The reason for the decreased yield was that the aromatic aldehyde underwent ring-opening reactions. The possible mechanism of the degradation indicated that the number of methoxyl groups on the phenolic ring determined the stability of the key intermediate of this reaction. The conversion of isoeugenol to vanillin during the AWOP at 60 ºC was > 99%, and the vanillin yield and selectivity were both 69.8%, indicating that the decrease in yield of the product from this degradation of lignin substrate and the product can be reduced or avoided in the AWOP at suitable temperature.

Flow behavior and microstructure characteristics of a Mo–V–Ti micro-alloyed high-strength steel were investigated through hot compression tests with two procedures. In group 1, the specimens were quenched after deformation at temperature range of 800–1100 °C, with strain rate of 10/s. Initiation of dynamic transformation (DT) and dynamic recrystallization (DRX) were confirmed by the evolution characteristics of work hardening rate (θ) during deformation. Critical stresses of both DT and DRX decreased with the increase in deformation temperature. The critical strain for DRX also decreased with the increase in temperature, while the critical strain of DT was less temperature dependent. In group 2, with different holding times at 630 °C after 3-pass deformation, complex precipitates were acquired from all the specimens. For the specimen that was water quenched after deformation, the particles were as fine as 20 nm. For the specimens that were held at 630 °C for 30–120 min, the particles were around 100–200 nm. Mo content in the precipitates decreased with holding time at 630 °C. V content in the particles is much less than Ti content because the Gibbs free energy of TiC is less than that of VC at the same temperature.

This research was focused on the failure analysis of a cracked SS304 stainless steel elbow from a chemical plant. The service life of the elbow was 2 years and 8 months. The elbow was welded with two straight pipes at two ends. Cracks were located mainly at positions close to the weld joint and the arc where very strong tensile residual stress existed. Corrosion pits were distributed on the inner surface of the elbow. Cracks were initiated from the corrosion pit bottoms. Branching was observed from the cracks. Cl and S elements were detected in corrosion products from the corrosion pits and the cracks by EDS. SEM results reviewed the intergranular and transgranular brittle nature of the fracture. It is concluded that stress corrosion cracking was the main reason for the cracking of the elbow.

Graphene/manganese dioxide composites and grapheme /manganese dioxide/sulfur (G/MnO2/ S) composite cathode were prepared by hydrothermal method and by vapor permeation, respectively. Their structure, morphology and specific surface area were characterized by X-ray diffraction, electron microanalysis and nitrogen adsorption analysis. The composites show morphology of nanosheets, high specific surface area and even distribution of sulfur. The sulfur accounts for 75% in the G/ MnO2/S composite by thermogravimetric analysis. The electrochemical performance of G/S and G/ MnO2/S cathode were investigated. The G/ MnO2/ S composite cathodes show excellent rate performance and cycle stability. At a 0.2C current density, initial discharge specific capacity is 1 061 mA·h·g−1 and maintains 698 mA·h·g−1 after 100 cycles; At a 1C current density, maximum discharge capacity reaches 816 mA·h·g−1 and average capacity decreasing rate is only 0.073%/ cycle after running over 400 cycles. Electrochemical mechanism of the composites cathodes was analyzed. The sulfur adsorption of MnO2 inhibited the loss of active material sulfur, so, the electrochemical performance of the complex was improved.

The failure (fracture) mechanism of a welded front axle tube structure made of C45E4 steel from a mini truck was analyzed. The fracture occurred on the right side of the right support frame with the fracture surface perpendicular to the tube axis. SEM examination showed that the fracture surface could be divided into three areas: intergranular area, cleavage area and dimple area. Crack initiation site of the failed front axle tube was at the front weld joint fixing the right support frame on the axle tube. The crack propagated in two opposite directions along the circumference of the tube and converged at the dimple area. Intergranular fracture was found to be in heat affected zone (HAZ). With higher magnification, fine dimples, intergranular and trans-granular fracture characteristics were observed in the crack initiation site. By metallurgical examination, Widmanstatten ferrites, which could decrease the toughness and strength of the weld joint, were observed in the columnar grains. The hardness of HAZ coarse grain area (623 VHN) was far higher than HAZ fine grain area (310 VHN) and base metal (225 VHN). As the weld process indicates, neither pre-weld nor post-weld treatment was carried out. A non-uniform temperature distribution around the weld joint could generate large thermal residual tensile stress in HAZ; thus, the material was very unstable. It could fracture for very small or even no external stress. Hydrogen atoms would be released during welding and microstructures with the highest hardness are the most susceptible of hydrogen assisted cracking. It is concluded that the fracture was caused by hydrogen assisted brittleness under the induction of weld residual stress. Post-weld aging treatment (PWAT) is recommended to release the residual stress generated during welding process. In this case, PWAT was carried out on the failed weld joint and Vickers hardness of HAZ coarse grain area, HAZ fine grain area and base metal decreased to 232 VHN, 205 VHN and 125 VHN, respectively. That indicates that the PWAT procedure could effectively soften the material and relieve residual stress.

Both the modeling and the load regulation capacity prediction of a supercritical power plant are investigated in this paper. Firstly, an indirect identification method based on subspace identification method is proposed. The obtained identification model is verified by the actual operation data and the dynamic characteristics of the system are well reproduced. Secondly, the model is used to predict the load regulation capacity of thermal power unit. The power, main steam pressure, main steam temperature and other parameters are simulated respectively when the unit load is going up and down. Under the actual constraints, the load regulation capacity of thermal power unit can be predicted quickly.

The condenser is an indispensable basic equipment in chemical industry. Due to the complex working conditions, leakage failure accidents often occur for condensers. In this work, the leakage failure of a spiral plate condenser made of 304 stainless steel has been investigated. The failed condenser, which had serviced for just six months, was used to condense isopropylamine by circulating frozen brine. After cutting and opening the condenser, numbers of leakage points were found occurring near the welding joints between the spacing columns and stainless steel spiral plates contacting with the frozen brine. The evidences indicate that leakage of the condenser is due to pitting corrosion caused by chloride ions near the welding joints between the spacing columns and stainless steel spiral plates. The sensitization of stainless steel in the welding zone intensifies the risk of pitting corrosion. Welding defects, including welding cracks and slag inclusions, are observed in the welding zone of the spacing columns, which might also aggravate the development of corrosion in the welding zone.

Morinda officinalis (MO) is a herb used in Traditional Chinese Medicine (TCM) for the treatment of osteoporosis. M13, a MO-based anthraquinone compound is known to suppress osteoclast activity. However, whether M13 promotes MSCs osteogenic differentiation and its potential mechanism remains unknown.To examine the influence of M13 on MSCs proliferation and osteogenic differentiation and elucidate the underlying mechanism.The effect of M13 exposure on MSCs proliferation was assessed via CCK8 assay, clone formation assay, immunofluorescence, RT-qPCR, and Western blot. The M13-mediated osteogenesis in vitro and ex vivo were evaluated via ALP and Alizarin red S staining, osteogenesis-associated gene (Runx2, Col1a1 and Opn) expression, and fetal limb explants culture. Molecular docking was employed for target signal pathway screening. The potential signaling mechanisms of M13-promoted MSCs osteogenic differentiation were analyzed by introducing XAV939 (Wnt/β-catenin signaling inhibitor).M13 induced certain obvious positive effects on MSCs proliferation and osteogenic differentiation. Treatment with M13 enhanced MSCs viability and clone numbers. Meanwhile, M13 promoted osteogenic gene expression, enhanced ALP intensity and Alizarin red S staining in MSCs. In terms of mechanism, M13 strongly interacted with the docking site of the WNT signaling complex, thereby activating the Wnt/β-catenin pathway. Furthermore, the M13-mediated osteogenic effect was partially inhibited by XAV939 both in vitro and ex vivo, which confirmed that the Wnt/β-catenin axis is a critical regulator of M13-induced osteogenic differentiation of MSCs.Our study elucidated for the first time that M13 significantly promoted osteogenic differentiation of MSCs via stimulation of the Wnt/β-catenin pathway in vitro and ex vivo.Our findings offered new additional evidence to support the MO or M13-based therapy of osteoporosis.