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The successful applications of silicon carbide-ceramic matrix composites (SiC-CMCs) in aeronautical and aerospace industries require deeper understanding of their mechanical behaviors and failure mechanisms. The overview on tension and shear is then presented from meso-mechanics perspective, including matrix cracking, interface de-bonding and sliding, matrix crack propagation as well as fiber bridging. The results reveal that the matrix cracking stress is proportional to the interface sliding stress and the matrix fracture energy. The ratio of tensile to shear stress of the matrix cracking remains constant both in tension and in shear. In addition, the deflection of matrix cracks in the interface depends on the elastic modulus matching parameter, the angle between matrix cracks and interface, as well as the residual thermal stress. The matrix cracks propagate in a random or periodic pattern, which are proportional to the sliding length at the matrix cracking stress. The fiber bridging mechanism, related to the Weibull distribution of the fiber strength, determines the tensile and shear behaviors after the saturation of matrix cracks.

This study employed optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) to investigate the impact of vanadium (V) on the microstructure and mechanical properties of gray cast iron (GCI) HT250. Additionally, Thermo-Calc software was employed to explore the influence of V on the solidification process. The results indicate that adding trace amounts of V in GCI forms a face-centered cubic VC phase, with the precipitation temperature of the VC phase gradually increasing. When the V content reaches 0.28 wt%, the VC phase begins to precipitate during the eutectic reaction. The incorporation of V consumes carbon, reducing the graphite content and promoting the formation of type D graphite. As the V content increases, there is an enlargement in the pearlite area ratio, a decrease in the pearlite layer spacing, and a reduction in the size of eutectic cells. These microstructural alterations lead to enhanced mechanical properties. The tensile strength peaks at 336 MPa with a V content of 0.77 wt%, representing a 29% increase compared to samples without added V. Similarly, the Vickers hardness increases with increasing V content, reaching a peak of 373 HV at 0.92 wt% V, a 27% increase compared to samples without V addition. However, at this point, the tensile strength decreases to 322 MPa.

The 7A04 Al alloy is a commonly used lightweight metal material; however, its low wear resistance limits its application. In this study, the wear resistance of this alloy was improved by preparing micro-arc oxidation (MAO) coatings, MAO/MoS2 composite coatings, and hard-anodized (HA) coatings on its surface. The friction and wear behaviors of these three coatings with diamond-like coated (DLC) rings under oil lubrication conditions were investigated using a ring–block friction tester. The wear rates of the coatings on the block surfaces were determined using laser confocal microscopy, and the wear trajectories of the coatings were examined using scanning electron microscopy. The results indicated that, among the three coatings, the MAO/MoS2 coating had the lowest coefficient of friction of 0.059, whereas the HA coating had the lowest wear rate of 1.47 × 10−6 mm/Nm. The MAO/MoS2 coatings exhibited excellent antifriction properties compared to the other coatings, whereas the HA coatings exhibited excellent anti-wear properties. The porous structure of the MAO coatings stored lubricant and replenished the lubrication film under oil lubrication. Meanwhile, the introduced MoS2 enhanced the densification of the coating and functioned as a solid lubricant. The HA coating exhibited good wear resistance owing to the dense structure of the amorphous-phase aluminum oxide. The mechanisms of abrasive and adhesive wear of the coatings under oil lubrication conditions and the optimization of the tribological properties by the solid–liquid synergistic lubrication effect were investigated. This study provides an effective method for the surface modification of Al alloys with potential applications in the aerospace and automotive industries.

Highlights The process of machine learning is introduced in detail. Recent developments in machine learning for low-dimensional electrocatalysts are briefly reviewed. Future directions and perspectives for machine learning in hydrogen evolution reaction are critically discussed.

The determination of ductile-to-brittle transition temperatures (DBTT) in intermetallic compounds is crucial for assessing their practical applications. In this study, we investigate the intrinsic factors influencing the DBTT of Fe–Al intermetallic compounds through feature engineering. We developed and evaluated two machine learning strategies for this task. Comparing the strategy that incorporates all features, including alloy compositions and atomic features, with the strategy utilizing selected features, it is found that the latter demonstrates superior computational efficiency and reduces overfitting. Specifically, surrogate models based on two selected features, namely cohesive energy and ionization energy, enable accurate prediction of the DBTT of Fe–Al intermetallics, achieving an accuracy of 95%. Additionally, through symbolic regression, we derived a functional expression that captures the relationship between variations in the DBTT and the selected features of intermetallic compounds. These findings have the potential to serve as a valuable guide for optimizing intermetallic compounds.

Two-step sintering to prepare gradient cemented carbides tends to the grain growth of hard phases, which adversely affects the mechanical properties. Spark plasma sintering is a promising pre-sintering process to mitigate grain growth by rapid prototyping and densification. In the present work, gradient cemented carbides with Ni binder instead of traditional Co binder were fabricated by both SPS pre-sintering and vacuum pre-sintering, followed by gradient sintering. The microstructure and elemental distributions of the prepared gradient cemented carbides were thoroughly investigated by XRD, SEM, EDS, EPMA and EBSD, focusing on the gradient layer formation and WC grain growth. The influence of WC grain size on the gradient layer formation was discussed with the aid of the DICTRA simulation. Finer WC grains in the SPS pre-sintered alloy show a smaller tortuosity factor, resulting in a thicker thickness of the gradient surface layer. The variations of hardness from the surface to the interior and the fracture toughness of the bulk for the gradient cemented carbides with different pre-sintering methods were measured through the micro-indentation method. Higher hardness and fracture toughness were obtained by SPS pre-sintered gradient cemented carbide.

Four Si3N4 crystal structures were predicted using an ab initio evolutionary methodology. The mechanical and dynamic stabilities were confirmed by the density functional theory assuming zero-pressure conditions. Energetic stability calculations indicated that the structures are metastable phases at ambient pressure, but their formation is more favorable at high pressures. At zero pressure, the densities of the hp-Si3N4, cp-Si3N4, oc-Si3N4, and ti-Si3N4 phases were 3.21, 3.28, 3.70, and 3.24 g/cm3, respectively. The calculated band structures and densities of states indicated that they have semiconductive properties, with gaps ranging from 0.754 to 3.968 eV. Mechanical property calculations revealed that the hardness of the Si3N4 compounds ranged between 11.2 and 23.3 GPa, which were higher than the corresponding values for the synthesized Si3N4 phases. These four Si3N4 structures are potentially valuable candidates for the synthesis of Si3N4 compounds.

BackgroundLittle is known about the role of interleukin (IL) in patients with acute myocardial infarction (MI), especially soluble IL-2 receptor (sIL-2R) and IL-8. We aim to evaluate, in MI patients, the predictive value of serum sIL-2R and IL-8 for future major adverse cardiovascular events (MACEs), and compare them with current biomarkers reflecting myocardial inflammation and injury.MethodsThis was a prospective, single-center cohort study. We measured serum concentrations of IL-1β, sIL-2R, IL-6, IL-8 and IL-10. Levels of current biomarkers for predicting MACEs were measured, including high-sensitivity C reactive protein, cardiac troponin T and N-terminal pro-brain natriuretic peptide. Clinical events were collected during 1-year and a median of 2.2 years (long-term) follow-up.ResultsTwenty-four patients (13.8%, 24/173) experienced MACEs during 1-year follow-up and 40 patients (23.1%, 40/173) during long-term follow-up. Of the five interleukins studied, only sIL-2R and IL-8 were independently associated with endpoints during 1-year or long-term follow-up. Patients with high sIL-2R or IL-8 levels (higher than the cutoff value) had a significantly higher risk of MACEs during 1-year (sIL-2R: HR 7.7, 3.3–18.0, p

Refractory Mo–10%Nb sputtering targets play a key role in the electronic integrated circuit and flat panel display industries. However, the fabrication of high-performance Mo–10%Nb sputtering targets is a challenging task. In order to improve the sintering densification and homogeneity of Mo–10%Nb targets, activated Mo–10%Nb solid-solution powders were prepared and characterised in our previous study. In this research, the structural stability, deoxidation characteristics, and sintering behaviours of activated Mo–10%Nb solid-solution powders were investigated. The results revealed that the crystal structure and composition of the activated powders had good stability when stored in vacuum at room temperature for 30 days. Further, the oxygen content of the activated powders was mainly concentrated at the surface, as confirmed by electron probe microanalysis and X-ray photoelectron spectrometry. The oxygen content could be significantly decreased from ∼6000 to ∼3000 ppm by a deoxidation process using Mg as the reductant. Finally, the density of the sintered billet increased from 86.19 to 91.36% upon using the Mo–10%Nb solid-solution powder, and the homogeneity of the composition and microstructure was greatly improved. Moreover, the average grain size decreased from 20.89 to 6.69 μm. This research suggests that activated Mo–10%Nb solid-solution powders can effectively improve the quality of sintered Mo–10%Nb targets.

Abstract Background Airway remodelling is the major pathological feature of chronic obstructive pulmonary disease (COPD), and leads to poorly reversible airway obstruction. Current pharmacological interventions are ineffective in controlling airway remodelling. In the present study, we investigated the potential role of artesunate in preventing and treating airway remodelling and the underlying molecular mechanisms in vitro and in vivo. Methods A COPD rat model was established by cigarette smoke (CS) exposure. After 12 weeks of artesunate treatment, pathological changes in the lung tissues of COPD rats were examined by ELISA and histochemical and immunohistochemical staining. A lung functional experiment was also carried out to elucidate the effects of artesunate. Human bronchial smooth muscle (HBSM) cells were used to clarify the underlying molecular mechanisms. Results Artesunate treatment inhibited CS-induced airway inflammation and oxidative stress in a dose-dependent manner and significantly reduced airway remodelling by inhibiting α-smooth muscle actin (α-SMA) and cyclin D1 expression. PPAR-γ was upregulated and TGF-β1/Smad2/3 signalling was inactivated by artesunate treatment in vivo and in vitro. Furthermore, PPAR-γ knockdown by siRNA transfection abolished artesunate-mediated inhibition of HBSM cell proliferation by activiting the TGF-β1/Smad2/3 signalling pathway and downregulating the expression of α-SMA and cyclin D1 in HBSM cells. Conclusions These findings suggest that artesunate could be used to treat airway remodelling by regulating PPAR-γ/TGF-β1/Smad signalling in the context of COPD.

Lithium–sulfur (LiS) batteries have been widely studied, and considered as one of the most promising energy storage systems, because of their superior theoretical energy density, non-toxicity, high abundance, and environmental friendliness. However, LiS batteries suffer from problems such as the electrical insulating characteristic of sulfur and unsatisfactorily long cycling life. As a superior type of carbon material, graphene have been intensively investigated as intermediate layers to overcome these problems because of its large surface area, good chemical stability, and excellent electrical conductivity. In this review, we summarize the recent application of graphene-based materials, including simple graphene and graphene-based nanocomposites, as modifying interlayers in LiS batteries. Furthermore, the strategies to enhance their electrochemical performance are summarized and discussed, for example, physical and chemical confinement. Finally, the limitation and challenges of graphene-based materials as interlayers for LiS batteries, as well as their prospects for future research, are proposed. We hope that this review will be helpful for scientists to design and fabricate high-performance LiS batteries based on graphene-based interlayers and boost their practical applications.

With outstanding high-temperature properties, the intermetallic Mo5SiB2 alloy is regarded as an extremely competitive ultra-temperature structural material. The maximum Young’s modulus of 398.0 GPa for single Mo5SiB2 crystals was found to be at the vertex of the [010] direction, while the minimum value of 264.0 GPa was found in the [001] direction. For hardness, the maximum value was 451.7 HV after compression at 1200 °C in the radial direction, while the maximum hardness was 437.2 HV at 1300 °C in the axial direction of {111}, showing obvious anisotropy. Under compression, the flow stresses rapidly increased and then decreased with the increase in strain, corresponding to the two different stages of work hardening and softening. An EBSD test showed that the grain orientation remained the same at different rates, but the texture was different. After high-temperature compression, the crystal underwent plastic deformation, dislocations slipped along the slip plane, and the grain rotated, so the grain texture changed from {111} to {001}.

At present, most studies focus on Cu-W composites with high W content (W content > 50 wt%), while there are only sporadic reports on Cu-W composites with low W content (W content < 50 wt%). In this work, Cu-W composites with different W contents (0, 10 wt%, 20 wt% and 30 wt%) were prepared, and the effects of W content on microstructure, density, hardness, electrical conductivity, strength and electrical contact properties were systematically studied, with the expectation of providing an experimental basis and theoretical support for expanding the application range of Cu-W composites with low W content. The results showed that, with the increase in W content, the Cu matrices divided into finer and more uniform grains; the density and electrical conductivity of Cu-W composites decreased; and the compressive yield strength and hardness gradually increased. As the content of W increased, the arc burning time of the Cu-W composite contacts began to fluctuate. There was a loss of both the cathode and the anode contacts of the pure Cu, but the mass transfer of the Cu-W composite contacts occurred as follows: the anode weight increases, while the cathode weight decreases. The addition of W particles changed the non-uniform ablation of the pure Cu, and the surface ablation of the Cu-W composite contacts remained uniform.

As a high-efficiency energy storage and conversion device, lithium-ion batteries have high energy density, and have received widespread attention due to their good cycle performance and high reliability. However, currently commercial lithium batteries usually use organic solutions containing various lithium salts as liquid electrolytes. In practical applications, liquid electrolytes have many shortcomings and shortcomings, such as poor chemical stability, flammability, and explosion. Therefore, the liquid electrolyte has a great safety hazard. The use of solid electrolyte ensures the safety of lithium-ion batteries, and has the advantages of high energy density, good cycle performance, long life, and wide electrochemical window, making the battery safer and more durable, with higher energy density and simple battery Structural design. Solid electrolytes mainly include inorganic solid electrolytes and organic polymer solid electrolytes. Although both inorganic solid electrolytes and polymer solid electrolytes have their own advantages, as far as the existing research work is concerned, whether it is an inorganic system or a polymer system, a single-system solid electrolyte can never achieve the full performance of an ideal solid electrolyte. The composite solid electrolyte composed of active or passive inorganic filler and polymer matrix is considered as a promising candidate electrolyte for all-solid-state lithium batteries. Among many polymer systems, PEO-based is considered to be the most ideal polymer substrate. In this review article, we first introduced the structure, properties, and preparation methods of PEO-based polymer electrolytes. Furthermore, the researches related to the modification of PEO-based polymer solid electrolytes in recent years are summarized. The contribution of polymer structural modification and the introduction of additives to the ionic conductivity, electrochemical stability and mechanical properties of PEO-based solid electrolytes is described. Examples of different composite solid electrolyte design concepts were extensively discussed, such as inorganic inert nanoparticles/PEO, oxide/PEO, and sulfide/PEO. Finally, the future development direction of composite solid electrolytes was prospected.

High chromium cast irons are commonly used as casting infiltration layers in the applications of wear resistance. The formation mechanism of the casting infiltration layer is essential to better develop the surface wear resistance materials using the casting infiltration method. In the present work, casting infiltration layers with various Cr contents were fabricated in situ on the surface of parent ZG45 steel. CALPHAD-type calculations using Thermo-Calc software, SEM, EDS and microhardness tests were performed to study the effect of Cr on the microstructure and hardness of casting infiltration layers. All the microstructures of casting infiltration layers were composed of pearlite matrix and eutectic M7C3 carbide. With the increase in Cr content from 7.01 wt.% to 17.20 wt.%, the amount of M7C3 carbide increased from 5.05 vol.% to 13.12 vol.%, resulting in the increment of microhardness. With the aid of simulations, the solidification behavior and formation mechanism of casting infiltration layers were revealed.

Iron oxides are potential electrode materials for lithium-ion batteries because of their high theoretical capacities, low cost, rich resources, and their non-polluting properties. However, iron oxides demonstrate large volume expansion during the lithium intercalation process, resulting in the electrode material being crushed, which always results in poor cycle performance. In this paper, to solve the above problem, iron oxide/carbon nanocomposites with a hollow core–shell structure were designed. Firstly, an Fe2O3@polydopamine nanocomposite was prepared using an Fe2O3 nanocube and dopamine hydrochloride as precursors. Secondly, an Fe3O4@N-doped C composite was obtained by means of further carbonization treatment. Finally, Fe3O4@void@N-Doped C-x composites with core–shell structures with different void sizes were obtained by means of Fe3O4 etching. The effect of the etching time on the void size was studied. The electrochemical properties of the composites when used as lithium-ion battery materials were studied in more detail. The results showed that the sample that was obtained via etching for 5 h using 2 mol L−1 HCl solution at 30 °C demonstrated better electrochemical performance. The discharge capacity of the Fe3O4@void@N-Doped C-5 was able to reach up to 1222 mA g h−1 under 200 mA g−1 after 100 cycles.

Heteroatom-doped carbon is widely used in the fields of adsorbents, electrode materials and catalysts due to its excellent physicochemical properties. N and S co-doped porous carbon spheres (N,S-PCSs) were synthesized using glucose and L-cysteine as carbon and heteroatom sources using a combined hydrothermal and KOH activation process. The physicochemical structures and single-factor methylene blue (MB) adsorption properties of the N,S-PCSs were then studied. The optimized N,S-PCSs-1 possessed a perfect spherical morphology with a 2–8-μm diameter and a large specific area of 1769.41 m2 g−1, in which the N and S contents were 2.97 at% and 0.88 at%, respectively. In the single-factor adsorption experiment for MB, the MB adsorption rate increased with an increase in carbon dosage and MB initial concentration, and the adsorption reached equilibrium within 2–3 h. The pseudo-second-order kinetic model could excellently fit the experimental data with a high R2 (0.9999). The Langmuir isothermal adsorption equation fitted well with the experimental results with an R2 value of 0.9618, and the MB maximum adsorption quantity was 909.10 mg g−1. The adsorption of MB by N,S-PCSs-1 was a spontaneous, endothermic, and random process based on the thermodynamics analyses. The adsorption mechanism mainly involved Van der Waals force adsorption, π-π stacking, hydrogen bonds and Lewis acid–base interactions.

Effects of tempering temperature on impact wear of 30Cr3Mo2WNi hot-working die steel are investigated by SEM, TEM, hardness, and impact wear tests. From 300 to 680°C, the hardness of the steel decreases and the impact toughness increases with increasing tempering temperature, while a secondary hardening with maximum hardness, 48.6 HRC, is achieved at 550°C. Fatigue delamination wear is the main mechanism during the impact wear, and three typical damage features are identified with different tempering temperatures. Brittle fatigue cracks are easy to occur in the steels tempered at 300°C. Ductile fatigue cracks occur at medium temperatures. Surfaces of steel tempered are extruded at 680°C.

The objective of this study was to investigate the current situation of vancomycin (VAN)-associated acute kidney injury (VA-AKI) in China and identify the risk factors for VA-AKI, as well as to comprehensively examine the risk related to concurrent drug use. Further, we assessed the outcomes of patients who developed VA-AKI and the risk factors for these outcomes. Finally, we aimed to provide suggestions for improving the prevention and treatment of VA-AKI in China.We conducted a retrospective observational study of inpatients who had been treated with VAN between January 2013 and December 2013 at Peking University First Hospital. AKI was defined as an increase in SCr of ≥0.3 mg/dl (≥26.5 μmol/l) within 48 hours or an increase to ≥1.5 times the baseline certainly or presumably within the past 7 days. VA-AKI was defined as the development of AKI during VAN therapy or within 7 days following the termination of VAN therapy. In addition, we compared patients with NO-AKI, who did not develop AKI during their hospitalization, with those with VA-AKI.Of the 934 patients treated with VAN during their hospital stay, 740 were included in this study. Among those excluded, 38.1% (74/194) were excluded because of a lack of data on serum creatinine (SCr). Among the included patients, 120 had confirmed VA-AKI, with an incidence of 16.2% (120/740). Multiple logistic regression analysis revealed that an elevated baseline estimated glomerular filtration rate (eGFR) (odds ratio [OR] = 1.009; p = 0.017) and concomitant vasopressor therapy (OR = 2.942; p = 0.009), nitrate use (OR = 2.869; p = 0.007), imipenem-cilastatin treatment (OR = 4.708; p = 0.000), and contrast medium administration (OR = 6.609 p = 0.005) were independent risk factors for VA-AKI; in addition, the receipt of orthopedic/trauma/burn surgery (OR = 0.3575; p = 0.011) and concomitant compound glycyrrhizin use (OR = 0.290; p = 0.017) were independent protective factors for VA-AKI. Multiple logistic regression analysis also demonstrated that among the patients who developed VA-AKI, coronary heart disease (CHD) (OR = 12.6; p = 0.006) and concomitant vasopressor therapy (OR = 15.4; p = 0.001) were independent risk factors for death. We also evaluated the factors influencing improvement of renal function. Multiple logistic regression analysis demonstrated that CHD (OR = 8.858, p = 0.019) and concomitant contrast medium administration (OR = 9.779, p = 0.005) were independent risk factors and that simultaneous β-blocker treatment (OR = 0.124, p = 0.001) was an independent protective factor for improvement of renal function.Patients treated with VAN received insufficient monitoring of SCr and inadequate therapeutic drug monitoring. We recommend that hospitals increase their investment in clinical pharmacists. An elevated baseline eGFR and concomitant vasopressor therapy, nitrate use, imipenem-cilastatin treatment, and contrast medium administration were independent risk factors for VA-AKI; in addition, orthopedic/trauma/burn surgery and concomitant compound glycyrrhizin use were independent protective factors for VA-AKI.

A binder plays an important role in lithium-ion batteries (LIBs), especially for the electrode materials which have large volume expansion during charge and discharge. In this work, we designed a cross-linked polymeric binder with an esterification reaction of Sodium Carboxymethyl Cellulose (CMC) and Fumaric Acid (FA), and successfully used it in an Sb2O3 anode for LIBs. Compared with conventional binder polyvinylidene fluoride (PVDF) and CMC, the new cross-linked binder improves the electrochemical stability of the Sb2O3 anode. Specifically, with CMC-FA binder, the battery could deliver ~611.4 mAh g−1 after 200 cycles under the current density of 0.2 A g−1, while with PVDF or CMC binder, the battery degraded to 265.1 and 322.3 mAh g−1, respectively. The improved cycling performance is mainly due to that the cross-linked CMC-FA network could not only efficiently improve the contact between Sb2O3 and conductive agent, but can also buffer the large volume charge of the electrode during repeated charge/discharge cycles.