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Upon 98% reduction cold-rolling, a single layer AA3003 foil material of 115 μm thick was intermediately annealed at 300–420 °C/1-8 h, and the preferred temperature and time of the intermediate annealing for the laminated AA4343/AA3003/AA4343 composite foil material were determined. All of these samples were cold rolled by 40% to 70 μm thick and finally annealed at a temperature in the range of 300–550 °C for 1–9 h. Their sagging resistance and microstructure were investigated using simulated brazing treatment, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For the single layer AA3003 foil, the sagging distance decreased first and then increased with increasing intermediate annealing temperature, and the lowest sagging distance corresponds to the coarsest grain in the recrystallized sample. After the final annealing for the single layer, the sagging distance decreased monotonously. For the laminated foil subjected to the final annealing, the sagging distance curves decreased first and then increased with increasing annealing temperature and time. The improvement of sagging resistance was attributed to the recovery of two types of materials during annealing process. The deterioration of the sagging resistance in the laminated foils was due to the corrosion in the brazing process, resulted from the Si diffusion from the cladding layer into the core layer. It is the coarse grains, few dislocations and minimal diffusion of Si that are crucial for improving the sagging resistance of the laminated foils.

Aging behavior and phase transformation of Al–5Zn–1Mg–1Cu(-Si) alloys under different isothermal temperatures were investigated using transmission electron microscope (TEM) and mechanical tests. The aging temperature and Si addition significantly influenced to the types of precipitated phases and mechanical properties of the Al–Zn–Mg–Cu alloys. Adding Si in this alloy changed the precipitated phases from T′ and η′ phases to the dual-sized η and GPB-II phases. With increasing isothermal aging temperature, more GPB-II phases formed in alloys with the same composition, effectively improving the microhardness and mechanical properties. When aging at 150 °C, 0.5 wt%Si-containing alloy reached the highest peak hardness of about 150HV and maintained stable hardness, while an alloy without Si only reached 120HV and later declined by 15HV. The tensile strength and yield strength of the 0.5 wt%Si-containing alloy were higher than those of non-Si alloy by 132 MPa and 165 MPa, increasing 51% and 90%, respectively. This result was due to the presence of fine and dispersed 4–8 nm GPB-II phases in 0.5 wt%Si-containing alloy. The GPB-II phase had a core-shell structure, with the core region mainly enriched in Mg and Si, and the shell region mainly enriched in Cu and Zn. Compared with the stability of T′ and η′ phases, this core-shell structure of GPB-II effectively inhibited its growth and beneficially maintained a smaller-sized GPB-II phase. The strengthening effect of GPB-II phase was better than that of η or T phases when aging at 150 °C or 200 °C. The mechanical properties of high Zn/Mg ratios Al–Zn–Mg–Cu alloys can enhanced by adding Si.

Abstract Pyroptosis, an inflammatory caspase-dependent programmed cell death, plays a vital role in maintaining tissue homeostasis and activating inflammatory responses. Orthodontic tooth movement (OTM) is an aseptic force-induced inflammatory bone remodeling process mediated by the activation of periodontal ligament (PDL) progenitor cells. However, whether and how force induces PDL progenitor cell pyroptosis, thereby influencing OTM and alveolar bone remodeling remains unknown. In this study, we found that mechanical force induced the expression of pyroptosis-related markers in rat OTM and alveolar bone remodeling process. Blocking or enhancing pyroptosis level could suppress or promote OTM and alveolar bone remodeling respectively. Using Caspase-1 −/− mice, we further demonstrated that the functional role of the force-induced pyroptosis in PDL progenitor cells depended on Caspase-1. Moreover, mechanical force could also induce pyroptosis in human ex-vivo force-treated PDL progenitor cells and in compressive force-loaded PDL progenitor cells in vitro, which influenced osteoclastogenesis. Mechanistically, transient receptor potential subfamily V member 4 signaling was involved in force-induced Caspase-1-dependent pyroptosis in PDL progenitor cells. Overall, this study suggested a novel mechanism contributing to the modulation of osteoclastogenesis and alveolar bone remodeling under mechanical stimuli, indicating a promising approach to accelerate OTM by targeting Caspase-1.

The effects of Si addition to Fe on the formation and growth of intermetallic compounds (IMC) in Fe/Al composites were studied by Scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques. The results showed that: when annealing time was 1 h, the critical IMC formation temperature of Pure Al/Pure Fe, Pure Al/Fe+0.82Si, Al+0.88Si/Pure Fe and Al+0.88Si/Fe+0.82Si were 440 °C, 480 °C, 520 °C and 620 °C, respectively. The major IMC phase formed in the four composites after heat treatments at 640 °C/1h and 640 °C/24h was the η phase (Fe2Al5), and a large number of θ phase (Fe4Al13) particles were present in the η phase for the Pure Al/Pure Fe sample. When Si element was added to Fe and Al, Fe3Al2Si3 phase and FeAl2Si phase were observed in the η phase. The thickness of the formed IMC layer in the four composites after heat treatment at 640 °C/1h was in the order: Pure Al/Pure Fe ≈ Pure Al/Fe+0.88Si > Al+0.888Si/Pure Fe ≈ Al+0.888Si/Fe+0.88Si. The growth activation energies of the IMC layer in the Pure Al/Pure Fe, Pure Al/Fe+0.82Si, Al+0.88Si/Pure Fe, Al+0.88Si/Fe+0.82Si samples were 76.1 kJ/mol, 276 kJ/mol, 349 kJ/mol and 519.6 kJ/mol, respectively. The effect of Si atoms on the formation of IMC was mainly by the interfacial enrichment mechanism and the new phase inhibition mechanism of FexAlySiz. The enrichment of Si at the interface of Al and Fe increased the growth activation energy and reduce the growth rate of IMC layer thickness. The formation of new FexAlySiz phase can inhibit the rapid growth of IMC phase along the C axis.

Background and aimSymptomatic intracranial hemorrhage (sICH) was the most serious complication associated with alteplase intravenous thrombolysis (IVT) in acute ischemic stroke (AIS) patients. However, the relationship between serum sodium levels and post-thrombolysis symptomatic intracranial hemorrhage has not been investigated. Therefore, the aim of this study was to investigate the relationship between pre-thrombolysis serum sodium levels and sICH after IVT, as well as to explore the optimal pre-thrombolysis serum sodium levels for lowering the risk of sICH following IVT.MethodsFrom July 1, 2017 to April 30, 2023, out-of-hospital AIS patients who received IVT in the emergency department were enrolled in this study. Serum sodium levels were measured at admission prior to IVT, and National Institutes of Health Stroke Scale scores were continuously assessed during and after thrombolysis. Routine follow-up neuroimaging was performed between 22 to 36 h after IVT. Initially, three logistic regression models and restricted cubic splines (RCS) were established to investigate the relationship between serum sodium levels and post-thrombolysis sICH. Furthermore, to evaluate the predictive value of serum sodium for post-thrombolysis sICH, we compared area under the receiver operating characteristic curve (AUROC) and net reclassification improvement (NRI) before and after incorporating serum sodium into traditional models. Finally, subgroup analysis was conducted to explore interactions between serum sodium levels and other variables.ResultsA total of 784 AIS patients who underwent IVT were enrolled, among whom 47 (6.0%) experienced sICH. The median serum sodium concentration for all patients was 139.10 [interquartile ranges (IQR): 137.40–141.00] mmol/L. Patients who developed sICH had lower serum sodium levels than those without sICH [138.20(IQR:136.00–140.20) vs. 139.20(IQR:137.40–141.00), p = 0.031]. Logistic regression analysis (model 3) revealed a 14% reduction in the risk of post-thrombolysis sICH for every 1 mmol/L increase in serum sodium levels after adjusting for confounding variables (p

Abstract Infected bone defects are a major challenge in orthopedic treatment. Native bone tissue possesses an endogenous electroactive interface that induces stem cell differentiation and inhibits bacterial adhesion and activity. However, traditional bone substitutes have difficulty in reconstructing the electrical environment of bone. In this study, we develop a self-promoted electroactive mineralized scaffold (sp-EMS) that generates weak currents via spontaneous electrochemical reactions to activate voltage-gated Ca2+ channels, enhance adenosine triphosphate-induced actin remodeling, and ultimately achieve osteogenic differentiation of mesenchymal stem cells by activating the BMP2/Smad5 pathway. Furthermore, we show that the electroactive interface provided by the sp-EMS inhibits bacterial adhesion and activity via electrochemical products and concomitantly generated reactive oxygen species. We find that the osteogenic and antibacterial dual functions of the sp-EMS depend on its self-promoting electrical stimulation. We demonstrate that in vivo, the sp-EMS achieves complete or nearly complete in situ infected bone healing, from a rat calvarial defect model with single bacterial infection, to a rabbit open alveolar bone defect model and a beagle dog vertical bone defect model with the complex oral bacterial microenvironment. This translational study demonstrates that the electroactive bone graft presents a promising therapeutic platform for complex defect repair.

Abstract Adult tendon stem/progenitor cells (TSPCs) are essential for tendon maintenance, regeneration, and repair, yet they become susceptible to senescence with age, impairing the self-healing capacity of tendons. In this study, we employ a recently developed deep-learning-based efficacy prediction system to screen potential stemness-promoting and senescence-inhibiting drugs from natural products using the transcriptional signatures of stemness. The top-ranked candidate, prim-O-glucosylcimifugin (POG), a saposhnikovia root extract, could ameliorate TPSC senescent phenotypes caused by long-term passage and natural aging in rats and humans, as well as restore the self-renewal and proliferative capacities and tenogenic potential of aged TSPCs. In vivo, the systematic administration of POG or the local delivery of POG nanoparticles functionally rescued endogenous tendon regeneration and repair in aged rats to levels similar to those of normal animals. Mechanistically, POG protects TSPCs against functional impairment during both passage-induced and natural aging by simultaneously suppressing nuclear factor-κB and decreasing mTOR signaling with the induction of autophagy. Thus, the strategy of pharmacological intervention with the deep learning-predicted compound POG could rejuvenate aged TSPCs and improve the regenerative capacity of aged tendons.

The effects of Sc, Mg and Si elements in an Al-Cu alloy have been studied by means of hardness tests and transmission electron microscopy analysis. The experimental results show that additions of Sc, Mg and Si can improve the heat resistance of the Al-Cu alloy. The Sc/Mg/Si segregation-sandwiched structure is the most stable, when compared with Sc segregation or Si/Sc co-segregation at the interface of θ′/Al. The additions of Si and Mg promote the aging–hardening response of the Al-Cu alloy. Mg is a micro-alloying element with great potential in stabilizing the size of θ′ phases, which further promotes the number density greatly. Consequently, the Al-Cu alloy achieves a high strength, matched with excellent thermal stability, due to the microalloying of Sc/Mg/Si solutes.

The influence of grain size on the corrosion behavior of pure aluminum and the defect density and diffusion coefficient of surface passive films were investigated using electron backscatter diffraction (EBSD) and electrochemical testing techniques, based on the point defect model (PDM). Samples with three different grain sizes (23 ± 11, 134 ± 52, and 462 ± 203 μm) were obtained by annealing at different temperatures and times. The polarization curves and electrochemical impedance spectroscopy results for the pure aluminum in the 3.5% NaCl solution showed that with decreasing grain size, the corrosion current (icorr) decreased monotonously, giving rise to a noble corrosion potential and a large polarization resistance. The Motte–Schottky results showed that the passive films that formed on pure aluminum with fine grains of 23 ± 11 μm had a low density (3.82 × 1020 cm−3) of point defects, such as oxygen vacancies and/or metal interstitials, and a small diffusion coefficient (1.94 × 10−17 cm2/s). The influence of grain size on corrosion resistance was discussed. This work demonstrated that grain refinement could be an effective approach to achieving high corrosion resistance of passive metals.

This work aims to study the influence of laser power on the microstructural evolution of novel Ti–6Zr–5Fe alloy fabricated by selective laser melting (SLM). The microstructural evolutions of all top surfaces in SLM Ti–6Zr–5Fe alloy samples fabricated from 80 W to 140 W were investigated in depth. The microstructure in SLM Ti–6Zr–5Fe alloy includes α phase and β phase, the size of the β phase and α phase increases with the increase of laser power due to the decrease of cooling rate. Meanwhile, the melt pool overlapping width increases with the increase of melt pool width due to the increase of laser power. The increase of melt pool overlapping causes the re-heating or re-melting of SLM Ti–6Zr–5Fe alloy. Moreover, as the laser power increases from 80 W to 140 W, the change of the melt pool greatly influenced the size, morphology, crystallographic orientation of the β phase, and their distributions. The increase of laser power causes adequate precipitation of the α phase, which improves the microhardness from 466 HV to 533 HV. The laser power can effectively regulate and control the microstructure and microhardness of SLM Ti alloys.

Abstract Macrophages are involved mainly in the balance between inflammation and tenogenesis during the healing process of tendinopathy. However, etiological therapeutic strategies to efficiently treat tendinopathy by modulating macrophage state are still lacking. In this study, we find that a small molecule compound Parishin-A (PA) isolated from Gastrodia elata could promote anti-inflammatory M2 macrophage polarization by inhibiting gene transcription and protein phosphorylation of signal transducers and activators of transcription 1. Local injection or sustained delivery of PA by mesoporous silica nanoparticles (MSNs) could almost recover the native tendon’s dense parallel-aligned collagen matrix in collagenase-induced tendinopathy by modulating macrophage-mediated immune microenvironment and preventing heterotopic ossification. Especially, MSNs decrease doses of PA, frequency of injection and yield preferable therapeutic effects. Mechanistically, intervention with PA could indirectly inhibit activation of mammalian target of rapamycin to repress chondrogenic and osteogenic differentiation of tendon stem/progenitor cells by influencing macrophage inflammatory cytokine secretion. Together, pharmacological intervention with a natural small-molecule compound to modulate macrophage status appears to be a promising strategy for tendinopathy treatment.

The Al–Mn alloy heat exchanger fin production process includes a brazing treatment at s high temperature of 600 °C, in which coarse grains are preferred for their high resistance to deformation at elevated temperatures by decreasing the grain boundary sliding. In this study, Al-1.57Mn-1.57Zn-0.58Si-0.17Fe alloy foils cold rolled by 81.7% (1.1 mm in thickness) and 96.5% (0.21 mm in thickness) were annealed at 100–550 °C for 1 h to investigate their recrystallization behavior, grain sizes, and precipitates by increasing the annealing temperature, using micro-hardness measurement, electron back-scattered diffraction (EBSD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The micro-hardness results showed that the recrystallization finishing temperatures for the two samples were almost the same, 323 ± 2 °C. The EBSD results showed that when the annealing temperature decreased from 550 to 400 °C, the recrystallized grain sizes of the two samples were nearly identical—both increased slightly. Further decreasing the annealing temperature from 400 to 330 °C caused the grain sizes to increase more, with the thinner foil sample having a more significant increase. The SEM and TEM observations showed that the micron-sized primary-phase remained unchanged during the annealing process. The nano-sized secondary phase precipitates formed during the hot-rolling process experienced a coarsening and dissolving process upon annealing. The particle size of the secondary phase increased from 32 nm to 44 nm and the area fraction decreased from 4.2% to 3.8%. The nucleation analysis confirmed that the large primary-phase could act as a nucleation site through particle stimulated nucleation (PSN) mode. The relatively dense secondary phase precipitates with small sizes at lower temperatures could provide higher Zener drag to the grain boundaries, leading to fewer nuclei and thereafter coarser grains. The coarsening of the recrystallized grains in the foils could be implemented through thickness reduction and/or precipitation processes to form densely distributed nano-sized precipitates.

Background: Scarless endoscopic thyroidectomy (ET) is increasingly accepted by the growing amount of surgeons. The target of this study is to assess the efficacy and summarise the experiences of total areola approach for ET (TAAET). Subjects and Methods: TAAET was performed on 529 patients between January 2016 and October 2021. All operated patients were divided into two groups according to the chronological order. Demographic data, perioperative data and post-operative complications were collected to assess the effectiveness of TAAET. Results: Five hundred and twenty-eight patients were successfully treated with TAAET, while 1 case was converted to open surgery due to bleeding. The surgical approach consists of lobectomy or total thyroidectomy with or without central lymph node dissection. The post-operative pathology of 433 (81.9%) patients was diagnosed with T1 ~2N0M0. The average number of unilateral lymph node dissection was 7.72 ± 2.44 while the bilateral lymph node was 10.70 ± 3.72. In terms of complications, 38 cases had transient hoarseness, 28 cases had tetany and numbness, 3 cases had post-operative bleeding, 1 case had infection and 33 cases had subcutaneous fluid. There were statistically significant differences between the two groups with respect to transient hoarseness (P < 0.001), tetany and numbness (P = 0.005), intraoperative blood loss (P = 0.003) and operation time for malignant tumour (P < 0.001) because of the accumulation of surgical experience and the maturation of technology. Conclusions: TAAET which conforms to the anatomical pathway of open thyroidectomy is a safe, effective and feasible technique and is highly suitable for novices.

Abstract Background In the context of climate change, it has been well observed that short-term temperature variability (TV) could increase the overall and cause-specific mortality and morbidity. However, the association between long-term TV and a broader spectrum of diseases is not yet well understood, especially in the elderly. Methods Our study used data from the fourth Urban and Rural Elderly Population (UREP) study. Long-term TV was calculated from the standard deviation (SD) of daily minimum and maximum temperatures within the study periods (2010–2014, 2011–2014, 2012–2014, 2013–2014, and 2014). Ten self-reported diseases and conditions were collected by questionnaire, including cataract, hypertension, diabetes, cardio-cerebrovascular diseases, stomach diseases, arthritis, chronic lung disease, asthma, cancer, and reproductive diseases. The province-stratified logistic regression model was used to quantify the association between long-term TV and the prevalence of each disease. Results A total of 184,047 participants were included in our study. In general, there were significant associations between TV and the prevalence of most diseases at the national level. Cardio-cerebrovascular disease (OR: 1.16, 95% CI: 1.13, 1.20) generated the highest estimates, followed by stomach diseases (OR: 1.15, 95% CI: 1.10, 1.19), asthma (OR: 1.14, 95% CI: 1.06, 1.22), chronic lung diseases (OR: 1.08, 95% CI: 1.03, 1.13), arthritis (OR: 1.08, 95% CI: 1.05, 1.11), and cataract (OR: 1.06, 95% CI: 1.02, 1.10). Moreover, the associations varied by geographical regions and across subgroups stratified by sex, household income, physical activity, and education. Conclusions Our study showed that long-term exposure to TV was associated with the prevalence of main diseases in the elderly. More attention should be paid to the elderly and targeted strategies should be implemented, such as an early warning system.

In order to improve the mechanical properties of Al–Si alloys fabricated by selective laser melting process, the microstructure and mechanical properties of Er/Zr modified A357 (Al–7Si-0.6 Mg) alloy in as-built and stress relief annealing conditions were studied. The results show that adding 0.15 wt.% Er helps to refine the cellular size, which is formed by eutectic Si network. The (Al,Si)3(Er,Zr) phases were precipitated during the solidification of Er–Zr composite modified sample, which could act as inoculants to promote the formation of equiaxed grains and refine the grain size. The average grain size of 0.8Er-0.4Zr sample was only 3.1 ± 1.4 μm. The yield strength, tensile strength and elongation reached 333 ± 2 MPa, 454 ± 1 MPa and 12.5 ± 1%, respectively. After stress relief annealing, eutectic Si was spheroidized and its size was increased, resulting in a decrease of strength and an increase of elongation. At the same time, the nano-sized L12-structure particles were precipitated in the Er–Zr composite modified sample, which would make up for the loss of strength and level it up to a certain extent. Therefore, Er–Zr composite modification could be an effective method to improve the comprehensive mechanical properties of SLM processed Al–Si alloys.

Isothermal hot compression experiments of homogenized Al–Mg–Si–Er–Zr alloy were conducted at temperatures ranging from 350 to 500 °C and strain rates of 0.01–10 s−1 on a Gleeble-3500 thermal simulation tester. The hot deformation behavior and optimum processing parameters of the alloy were determined by analyzing the flow curves and processing maps. Characterization of the microstructures of the deformed specimens was done using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), and the geometrically necessary dislocation (GND) density was used based on the kernel average misorientation (KAM). The results showed that the GND density decreased with a decrease in the strain rate and with an increase in the deformation temperature. Dynamic recovery and continuous dynamic recrystallization were the main softening mechanisms during hot deformation, and dynamic recovery was dominant. It was found that the capacity for dynamic recovery was reduced, while dynamic recrystallization was prevented in the Al–Mg–Si–Er–Zr alloy. This was a result of hindered dislocations and sub-grain boundary movement caused by the pinning of dislocations and sub-grain boundaries from the Mg2Si, Al(MnFe)Si, and Al3(Er, Zr) particles. The addition of Er and Zr resulted in an increase in the activation energy, which can be attributed to the formation of Al3(Er, Zr) particles.

Microstructural evolution and its effect on microhardness and Young's modulus of Ti–6Zr–4Fe alloy solution and aging treated at different temperatures were studied. The α phase transformed into β phase completely at 860 °C, meanwhile, the athermal ω phase was found at 860 °C and it resulted in a higher Young's modulus. The ω phase content increased from 250 °C to 400 °C, and the content decreased with further increase of aging temperature, there were only α phase and β phase at 600 °C. The phase transformation sequence was β → ω + β → ω + α + β → α + β during aging treatment. The microhardness increased from 315 HV to 492 HV due to the element solution strengthening and phase transformation strengthening. The peak microhardness of Ti–6Zr–4Fe alloy aged at 400 °C reached 652 HV. The formation of ω phase resulted in the increase of microhardness and Young's modulus in Ti–6Zr–4Fe alloy.

Process of hydrolysis of Dendrobium officinale polysaccharide by high temperature and pressure-sulfuric acid assisted was optimized by response surface method (RSM) according to Central Composite Design (CCD), and polysaccharides of Dendrobium officinale under the conditions of different cultivation were determined by phenol-sulfuric acid method, and the contents of mannose from different parts (stems, leaves and flowers) of Dendrobium officinale were analyzed by pre-column derivation HPLC method. The research showed that the optimum parameters was as follow: Material-liquid ratio was 1:1.5 (mg/mL), concentrations of sulfuric acid was 1 mol/L, hydrolysis temperature was 112 ℃ (0.15 MPa) and hydrolysis time was 44 min. Under optimal conditions, the content of the mannose was 64.35%±0.76% with stem as the test material. The contents of polysaccharide in stems, leaves and flowers of Dendrobium officinale under the conditions of same cultivation were significantly differences (Pleaves>flowers). And the contents of mannose in the samples was the same as that of polysaccharide. The content of polysaccharide and mannose in the stems were 29.32%~33.78% or 18.17%~21.05%, respectively. And the contents of polysaccharide and mannose in the leaves were 15.91%~17.31% or 10.28%~11.11%, respectively. And the contents of polysaccharide and mannose in the flowers were 8.37%~8.68% or 5.30%~5.75%, respectively. The results indicated that the method was effective and efficient, which could be used for the hydrolysis of Dendrobium officinale polysaccharide by high temperature and pressure-sulfuric acid assisted. And the stems, leaves and flowers of Dendrobium officinale were high-quality natural resources for the preparation of mannose.

Wetlands within dryland regions are highly sensitive to climate change and human activities. Based on three types of land use data sources from satellite images and a spatial data analysis, the spatiotemporal characteristics of wetland evolution in China’s drylands and their relationship with human interference and climate change from 1990 to 2020 were analyzed. The results were as follows: (1) The wetlands within China’s drylands expanded, including rivers, lakes, and artificial wetlands, apart from marshes, which shrunk. Meanwhile, wetland fragmentation increased, with rivers being particularly severely fragmented. (2) Temperature and precipitation showed an increasing trend from 1990 to 2020 in China’s drylands. Lakes and rivers expanded with regional differences due to the uneven distribution of precipitation and rising temperature. (3) Human activities, more than climate change, became the key driving factor for the changes in wetland patterns in China’s drylands. The increased areas of farmland and grassland along with increased levels of drainage and irrigation activities led to the shrinkage of marshes and the fragmentation of rivers. The increase in the number of artificial reservoirs was the main reason for the expansion of artificial wetlands. This study clarifies the specific driving factors of different types of wetlands within China’s drylands, which is of great use for better protecting wetlands and the gradual restoration of degraded wetlands.

The Al–7Si–0.6 Mg alloy with added rare earth erbium (Er) was prepared by laser powder bed fusion (LPBF) technology, and the effect of heat treatment on the microstructure and mechanical properties was studied. The addition of Er introduces Al3Er to the molten pool, which can effectively hinder the epitaxial growth of the columnar crystal. The effect of rapid cooling and the addition of Er can also modify eutectic Si particles, resulting in an ultrafine eutectic network cellular structure. Moreover, the as-built samples have an excellent tensile strength exceeding 438 MPa and a ductility of over 8%; furthermore, such excellent mechanical properties are associated with small grains, a continuous Si network, and extremely oversaturated solid solubility. After heat treatment, LPBF-processed alloy samples exhibit superior mechanical properties, especially after direct age treatment, which can mainly be attributed to the precipitation strengthening effect introduced by nanosized precipitates.

Al–Sn–Si alloys have been widely used as bearing alloys in automotive engines. In those alloys, β(Sn) phase serves as the solid lubricant and Si particles are used to improve the hardness, fatigue resistance as well as seizure resistance. With the development of machinery, bearing alloys with higher load-carrying capacity and better tribological properties are demanded to meet the application under severe conditions. Adding appropriate Mg to the Al–Sn–Si alloy can effectively optimize the tribological properties. In this paper, the microstructure, mechanical properties and tribological properties of the Al–12Sn–4Si-xMg (x = 0, 0.5, 1, 1.5, all in wt.%) alloys were studied. The Al–12Sn–4Si-1.5 Mg alloy had the smallest grain size and more uniform microstructure than other specimens. The Al–12Sn–4Si-1.5 Mg alloy showed significantly better wear resistance than the Al–12Sn–4Si alloy at 2 N–70 N. The volume wear rates and friction coefficients at 15 N–70 N were lower than those at 2 N–8 N. The evolution of volume wear rate and friction coefficient with load was related to the evolution of tribolayer with load. The wear mechanism of the alloys was mainly oxidation wear, adhesive wear and fatigue wear, accompanied with abrasive wear.

A novel Al-Mg-Si aluminum alloy with the addition of the micro-alloying element Er and Zr that was promptly quenched after extrusion has been studied. The solid solution and aging treatment of the novel alloy are studied by observing the microstructure, mechanical properties, and strengthening mechanism. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques are employed to examine the changes in the microstructure resulting from various solid solution treatments and aging treatments. The best strengthening effect can be achieved when the solubility of the MgSi phase and precipitate β″ (Mg2Si phase) is at their maximum. The addition of Er and Zr elements promotes the precipitation of the β″ phase and makes the b″ phase more finely dispersed. The aging strengthening of alloys is a comprehensive effect of the dislocation cutting mechanism and bypass mechanism, the joint effect of diffusion strengthening of Al3(Er,Zr) particles and the addition of Er and Zr elements promoting the precipitation strengthening of β″ phases. In this paper, by adding Er and Zr elements and exploring the optimal heat treatment system, the yield strength of the alloy reaches 437 MPa and the tensile strength reaches 453 MPa after solid solution treatment at 565 °C/30 min and aging at 175 °C/10 h.

In this paper, we propose an acoustic black hole radial elastic metamaterial (AREM). Through the study of its dispersion relations, it is found that, compared with the conventional elastic metamaterial, the AREM gathers energy at the tip of the black hole cell, which can trigger the local resonance (LR) effect and couples with the Bragg scattering (BS) effect, thus opening the very low-frequency strong attenuation broadband. The influence of the structural parameters of the AREM on the bandgap (BG) characteristics is further explored, and the bandwidth can be modulated in the frequency range of 0–1300 Hz by varying the truncation thickness and power exponent of the acoustic black hole (ABH) structure. Finally, by analyzing the transmission spectrum and displacement field, it is found that the total bandwidth of the flexural BG is better than that of the conventional radial elastic metamaterial, and the wave attenuation capability is improved by more than 110%. It is also discovered that the BG characteristics of the longitudinal BG are also better than those of the conventional radial elastic metamaterial, and the total bandwidth of the longitudinal BG is superior to that of the conventional radial elastic metamaterial, with the wave attenuation capability improved by more than 56%. The research findings may have applications in engineering fields such as ultra-low-frequency vibration reduction.

This paper centers on high-strength Al-Mg-Mn-Er-Zr alloy, which was developed through the addition of Er, a cheap rare earth element, and suitable for additive manufacturing (3D printing). The microstructure and mechanical properties of Al-Mg-Mn-Er-Zr alloy of as-built and heat treated samples have been characterized, which shows: the precipitation of Al3Zr primary phase at the boundary of molten pool promotes heterogeneous nucleation and refines the grains, which suppresses the formation of solidification cracking in Al-Mg alloy. To bring the Er-Zr synergistic effect into play during the aging heat treatment, the nano-scale precipitation phase of Al3Er that diffuses nucleation at an earlier stage promotes the precipitation of Zr, leading to the formation of Al3(Er,Zr) core-shell structure and enhancing precipitation strengthening effect. Under the combined effects of multiple strengthening mechanisms, the yield strength could reach 440 ± 3 MPa; tensile strength, 520 ± 2 MPa and elongation 15.5 ± 1.0 %.

This paper focuses on the effect of melting modes on microstructural evolution and tribological properties of AlSi10Mg alloy fabricated by selective laser melting (SLM). The results showed that the microstructures of SLM AlSi10Mg consisted of primary α-Al surrounded by cellular Si networks (∼500 nm) when fabricated in conduction mode, but has a finer cellular-like Si phase (∼200 nm) when fabricated in keyhole mode. The strong convection caused by the melt reflow and Marangoni convection under keyhole mode also resulted in deposition of nano-scale Si particles at the bottom of the molten pool. The SLM AlSi10Mg fabricated in keyhole mode exhibited better wear resistance than that fabricated in conduction mode. Compared to traditional as-cast specimens, both SLM specimens showed better wear resistance due to the unique cellular-like networks. The SLM technique offers a new approach for material processing that can be used to refine microstructures for improved tribological properties.

With the rapid development of the machinery industry, bearing materials with better tribological properties are demanded. Al alloys containing Erbium (Er) and Zirconium (Zr) have better comprehensive performance, whose tribological properties have hardly been reported before. In this work, dry sliding wear tests were performed on the Al–Sn and Al–Sn–Er–Zr alloys in two different annealing states to study the effect of trace Er, Zr on the tribological properties of the Al–Sn alloys. The Al–Sn–Er–Zr alloys showed better wear resistance than the Al–Sn alloys, which was mainly due to the higher hardness and strength of the Al–Sn–Er–Zr alloys. The wear losses of the alloys annealed at 375 °C for 100 h at the load of 70 N were significantly lower than those of the alloys annealed at 300 °C for 4 h. The wear coefficient K of the alloys annealed at 375 °C for 100 h decreased with the increasing load. The Al–Sn–Er–Zr alloys showed smoother worn surfaces than the Al–Sn alloys. With the load increasing, the wear mechanism changed from abrasive wear, mild adhesive wear and slight delamination wear to severe adhesive wear and delamination wear. The wear scars of different samples under the same load were similar, indicating that the addition of trace Er, Zr and annealing process did not change the wear mechanism. All samples experienced cracks and voids in the tribolayers. And oxygen accumulated in these defects. Most wear debris were lamellar, which was related to the adhesive wear and consist with the delamination theory.

Microbial diseases are a global health threat, leading to tremendous casualties and economic losses. The strategy to treat microbial diseases falls into two broad categories: pathogen-directed therapy (PDT) and host-directed therapy (HDT). As the typical PDT, antibiotics or antiviral drugs directly attack bacteria or viruses through discerning specific molecules. However, drug abuse could result in antimicrobial resistance and increase infectious disease morbidity. Recently, the exosome therapy, as a HDT, has attracted extensive attentions for its potential in limiting infectious complications and targeted drug delivery. Mesenchymal stem cell-derived exosomes (MSC-Exos) are the most broadly investigated. In this review, we mainly focus on the development and recent advances of the application of MSC-Exos on microbial diseases. The review starts with the difficulties and current strategies in antimicrobial treatments, followed by a comprehensive overview of exosomes in aspect of isolation, identification, contents, and applications. Then, the underlying mechanisms of the MSC-Exo therapy in microbial diseases are discussed in depth, mainly including immunomodulation, repression of excessive inflammation, and promotion of tissue regeneration. In addition, we highlight the latest progress in the clinical translation of the MSC-Exo therapy, by summarizing related clinical trials, routes of administration, and exosome modifications. This review will provide fundamental insights and future perspectives on MSC-Exo therapy in microbial diseases from bench to bedside.

The hot compression experiment of homogenized Al−5.2Mg−0.6Mn−0.29Zn−0.16Er–0.12Zr alloy was carried out by the Gleeble-3500 thermal simulation testing system. The deformation behavior in temperatures of 350~500 ℃ and deformation rates of 0.01~10 s−1 was studied. The relationship between stress and strain rate and deformation temperature was analyzed. The constitutive equation of alloy high-temperature deformation was constructed by the Zener–Hollomon method, and the hot working diagram with the true strain of 0.2 and 0.5 was constructed according to the dynamic material model. The research results show that flow stress has a positive correlation with strain rate and a negative correlation with temperature. The steady flow stress during deformation can be described by a hyperbolic sinusoidal constitutive equation. Adding Er and Zr into Al−Mg alloy can not only refine grains and strengthen precipitation but also form a core–shell Al3(Er, Zr) phase. In the deformation process, Al3(Er, Zr) precipitates can pin dislocations and inhibit dynamic recrystallization (DRX). Dynamic recovery (DRV) is dominant during hot deformation. The mechanism of dynamic recovery is dislocation motion. At high temperatures, Al3(Er, Zr) can also inhibit grain coarsening. The average hot deformation activation energy of the alloy is 203.7 kJ/mol. This high activation energy can be due to the pinning effect of Er and Zr precipitates. The processing map of the alloy was analyzed and combined with the observation of microstructure, the hot deformation instability zone of the alloy was determined, and the suitable process parameters for hot deformation were obtained, which were 450~480 °C, and the strain rate is 0.01~0.09 s−1.

A novel Al-Cu-Zr alloy is designed in this paper, which provides a method for further improving the strength of Al-Cu alloys. In this paper, the addition of the micro-alloying element Zr in Al-Cu alloy was studied. The effect of aging treatment on the mechanical properties and precipitation behavior of the alloy was studied. With the addition of Zr, Al3Zr phases were formed in the alloy, which acts as obstacles to dislocation motion. In addition, Al3Zr phases can be used as the nucleation site of θ′ phases to promote precipitation. All this can improve the strength of Al-Cu alloys. After one-step aging, corresponding to the highest hardness, the largest amount of θ′ phases were observed in the alloy matrix. By contrast, after two-step aging, the θ′ phases were finer, and a large amount of Guinier–Preston (GP) zones formed during the pre-aging step, which were transformed into denser and finer θ′ phases in the secondary aging step. After the same solution treatment (540 °C/12 h), undergoing 120 °C/4 h + 175 °C/10 h two-step aging, the ultimate tensile strength, yield strength, and elongation of the Al-Cu-Zr alloy were 398.7 MPa, 313.3 MPa, and 7.9%, respectively.

There is a development trend for fuel vehicles to adopt low-carbon emission engines. The sales of cars with low-carbon three-cylinder engines in the Chinese market have declined. Is the life cycle of automotive products with three-cylinder engines entering a recession stage? In order to achieve this research objective, which is to investigate whether assembling a three-cylinder engine affects the life cycle of an automotive product, this paper constructs an ecological theory-based approach to measuring the life cycle of automotive products. First, the logistic model is used to measure the intrinsic growth rate, internal inhibition coefficient, and theoretical upper limit of product sales scale before and after the automotive products are equipped with three-cylinder engines. In the second stage, the Lotka–Volterra model is used to calculate the intrinsic growth rate, internal inhibition coefficient, theoretical upper limit, and symbiosis coefficient of the sales scale of the products before and after the three-cylinder engine, taking the Chinese automobile manufacturing enterprises as an example for empirical analysis. The research results show that the selection of three- cylinder engine for automotive products will not lead to the product life cycle entering the recession period ahead of time.

For plug-in hybrid electric vehicle (PHEV), using a hybrid energy storage system (HESS) instead of a single battery system can prolong the battery life and reduce the vehicle cost. To develop a PHEV with HESS, it is a key link to obtain the optimal size of the power supply and energy system that can meet the load requirements of a driving cycle. Since little effort has been dedicated to simultaneously performing the component sizing of PHEV and HESS, this paper proposes an approach based on the particle swarm optimization (PSO) algorithm to simultaneously determine the sizes of the engine, motor, battery and supercapacitor (SC) in a PHEV with HESS. The drivetrain cost is minimized in a different all-electric range (AER)—and depends on the battery type—while ensuring the driving performance requirements. In addition, the effects of the power system and drive cycle on the component sizes were analyzed and compared. The simulation results show that the cost of the PHEV drivetrain with the Ni-MH battery/SC HESS is reduced by up to 12.21% when compared to the drivetrain with the Li-ion battery/SC HESS. The drivetrain cost is reduced by 8.79% when compared to analysis-based optimization. The type of power supply system and drive cycle can significantly affect the optimization results.

During the outbreak of novel coronavirus pneumonia, the number of confirmed cases and deaths in Hubei province of China increased sharply, and the situation in Hubei was more severe than that in non-Hubei, so we do a research on psychological health status evaluation of the public in Hubei and non-Hubei areas. In this paper, we adopt textual analysis and contextual analysis using Simplified Chinese Microblog Word Count (SCMBWC), Five-Factors Model (FFM), Semantic Role Labeling (SRL) to interpret and analyze the public perception and psychological personality based on media news. Through the analysis, it was found that there were great differences in public perception to novel coronavirus pneumonia. In Hubei areas, the public perception was mainly reflected in the overall prevention and the treatment of patients, while in non-Hubei areas, the perception was mainly in the orderly promotion of enterprises to return to work. Through contextual analysis, the novel coronavirus pneumonia had a great psychological impact on the public in different regions. The media covered a large number of social process words and cognitive process words, public showed a personality that was inclined to be “open” and “neurotic” in different areas. Furthermore, we find out some reasons like all kinds of rumors, wildlife trade, all kinds of illegal and criminal acts disturbing social order cause this psychology personality through emotional entity mining based on semantic role labeling. This is conducive to the government's better policies and management in line with local conditions.

Background: A simple scoring system for triage of suspected patients with COVID-19 is lacking. Methods: A multi-disciplinary team developed a screening score taking into account epidemiology history, clinical feature, radiographic feature, and routine blood test. At fever clinics, the screening score was used to identify the patients with moderate to high probability of COVID-19 among all the suspected patients. The patients with moderate to high probability of COVID-19 were allocated to a single room in an isolation ward with level-3 protection. And those with low probability were allocated to a single room in a general ward with level-2 protection. At the isolation ward, the screening score was used to identify the confirmed and probable cases after two consecutive real-time reverse transcription polymerase chain reaction (RT-PCR) tests. The data in the People’s Hospital of Changshou District were used for internal validation and those in the People’s Hospital of Yubei District for external validation. Results: We enrolled 76 and 40 patients for internal and external validation, respectively. In the internal validation cohort, the area under the curve of receiver operating characteristics (AUC) was 0.96 [95% confidence interval (CI): 0.89–0.99] for the diagnosis of moderate to high probability of cases among all the suspected patients. Using 60 as cut-off value, the sensitivity and specificity were 88% and 93%, respectively. In the isolation ward, the AUC was 0.94 (95% CI: 0.83–0.99) for the diagnosis of confirmed and probable cases. Using 90 as cut-off value, the sensitivity and specificity were 78% and 100%, respectively. These results were confirmed in the validation cohort. Conclusion: The scoring system provides a reference on COVID-19 triage in fever clinics to reduce misdiagnosis and consumption of protective supplies. The reviews of this paper are available via the supplemental material section.

The intergranular corrosion and β phase evolution of 5083 aluminum alloy containing Er and Zr during annealing at 100–230 °C were studied using mass loss tests and transmission electron microscopy. The mass loss curves showed that when annealing temperature changed from 200 to 220 °C, the alloy was subjected to a transition from sensitized state to stabilized state, corresponding to the change of nucleation position of β precipitates from grain boundaries to triple junctions. Particularly, when the annealing temperature was at 210 °C, this transition could also happen when the annealing time was increased from 0.5-10 h to 15-24 h, associated with the change in the shape of β precipitates. The classical nucleation analysis with the consideration of Mg segregation showed the nucleation rates at grain boundary and triple junction were 1013 and 1011 m−3 s−1 at sensitization temperature 150 °C, but 109 and 1010 m−3 s−1 at stabilization temperature 220 °C, suggesting the change of nucleation site with increasing temperature. The analysis of diffusion flux of Mg around β precipitate suggested that the shape change of β precipitates from elongate to spheroidal at 210 °C was attributed to the dominant interface diffusion over the grain boundary diffusion with the increase of time. Keywords: Aluminum alloy, Microstructure, Corrosion, Classical nucleation theory, Diffusion

The thermodynamics of five Al3Er compounds were investigated through first-principles density-functional theory (DFT) and experimental analysis. The Al3Er compounds with Al3Ho.hR20 (prototype Al3Ho, Pearson symbol hR20), Cu3Au.cP4, AlNd3.hP8, Ni3Ti.hP16 and Al3Gd.hR12 structures exhibited formation energies of −0.412(−0.417), −0.411(−0.416), −0.400(−0.413), −0.399(−0.345) and −0.342(−0.345) meV/atom when using DFT with “standard” potential (“frozen core” potential) of Er. The results indicated that the Al3Ho.hR20 structure was the thermodynamic stable phase and the other structures were metastable. The formation energy of Cu3Au.cP4 structure was only 1 meV/atom less than that of Al3Ho.hR20. Experimentally, the Al-30 wt.% Er alloys were cooled from 900 °C to 500 °C at the rate of 5 ± 2 °C/h and 60 ± 2 °C/h, respectively. The corresponding XRD analysis showed that the Al3Ho.hR20 was formed at the cooling rate of 5 ± 2 °C/h and the Cu3Au.cP4 was formed at the cooling rate of 60 ± 2 °C/h, which indicated that the Al3Ho.hR20 was in a thermodynamic stable phase and the Cu3Au.cP4 was in a metastable phase with high stability. The structural analysis indicated that the tiny energy difference between Al3Ho.hR20 and Cu3Au.cP4 might be attributed to a similar structure with varied stacking sequences.

This study focuses on the online learning abilities of university students, a crucial skill in today's digital age. This research collected data from students (n = 945) from China with a questionnaire of 40 questions in two scales. The researchers made factor analyses concerning university students' online learning ability, which included 19 Likert scale questions, and the influencing factors on online learning ability, which had 15 Likert scale questions. The former analysis yielded two factors that explained the students' online learning ability: students' ability in self-regulation and innovation; and ability in technology control, and information processing. The latter yielded two factors influencing the students' online learning ability: using learning resources; external support. Comparative analyses were also made, with results showing that the independent variables of gender, educational level, major, and family economic situation significantly influenced certain variables.

Using the uncertain conversion capacity between the expressions of quantitative and qualitative concept in the cloud model, an energy management strategy based on cloud model is developed for parallel hybrid vehicles (PHVs). By the driver input and the state of charge (SOC) of the energy storage, a set of rules are developed to effectively determine the torque split between the internal combustion engine (ICE) and the electric motor. An analysis of the simulation results is conducted using ADVISOR in order to verify the effectiveness of the proposed control strategy. It is confirmed that the control scheme can be used to improve fuel economy and emission of the hybrid vehicles.

BACKGROUND AND PURPOSE: NAD(P)H: quinone oxidoreductase 1 (NQO1) mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation is the dominant metabolic pathway of tanshinone IIA (TSA), a promising anti-cancer agent. UGTs are positively expressed in various tumor tissues and play an important role in the metabolic elimination of TSA. This study aims to explore the role of UGT1A in determining the intracellular accumulation and the resultant apoptotic effect of TSA. EXPERIMENTAL APPROACH: We examined TSA intracellular accumulation and glucuronidation in HT29 (UGT1A positive) and HCT116 (UGT1A negative) human colon cancer cell lines. We also examined TSA-mediated reactive oxygen species (ROS) production, cytotoxicity and apoptotic effect in HT29 and HCT116 cells to investigate whether UGT1A levels are directly associated with TSA anti-cancer effect. UGT1A siRNA or propofol, a UGT1A9 competitive inhibitor, was used to inhibit UGT1A expression or UGT1A9 activity. KEY RESULTS: Multiple UGT1A isoforms are positively expressed in HT29 but not in HCT116 cells. Cellular S9 fractions prepared from HT29 cells exhibit strong glucuronidation activity towards TSA, which can be inhibited by propofol or UGT1A siRNA interference. TSA intracellular accumulation in HT29 cells is much lower than that in HCT116 cells, which correlates with high expression levels of UGT1A in HT29 cells. Consistently, TSA induces less intracellular ROS, cytotoxicity, and apoptotic effect in HT29 cells than those in HCT116 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol can decrease TSA glucuronidation and simultaneously improve its intracellular accumulation, as well as enhance TSA anti-cancer effect. CONCLUSIONS AND IMPLICATIONS: UGT1A can compromise TSA cytotoxicity via reducing its intracellular exposure and switching the NQO1-triggered redox cycle to metabolic elimination. Our study may shed a light in understanding the cellular pharmacokinetic and molecular mechanism by which UGTs determine the chemotherapy effects of drugs that are UGTs' substrates.

Chirality is an interesting topic and it is meaningful to explore the interactions between chiral small molecules and stereoselective biomacromolecules, with pre-clinical and clinical significances. We have previously demonstrated that 20(S)-ginsenoside Rh2 is an effective P-glycoprotein (P-gp) inhibitor in vitro and in vivo. Considering the stereochemistry of ginsenoside Rh2, in our present study, the regulatory effects of 20(R)-Rh2 on P-gp were assayed in vivo, and the differential regulations of P-gp by ginsenoside Rh2 epimers in vivo were compared and studied. Results showed that 20(S)-Rh2 enhanced the oral absorption of digoxin in rats in a dose-dependent manner; 20(R)-Rh2 at low dosage increased the oral absorption of digoxin, but this effect diminished with elevated dosage of 20(R)-Rh2. Further studies indicated stereoselective pharmacokinetic profiles and intestinal biotransformations of Rh2 epimers. In vitro studies showed that Rh2 epimers and their corresponding deglycosylation metabolites protopanaxadiol (Ppd) epimers all exhibited stereoselective regulations of P-gp. In conclusion, in view of the in vitro and in vivo dispositions of Rh2 and the regulations of P-gp by Rh2 and Ppd, it is suggested that the P-gp regulatory effect of Rh2 in vivo actually is a double actions of both Rh2 and Ppd, and the net effect is determined by the relative balance between Rh2 and Ppd with the same configuration. Our study provides new evidence of the chiral characteristics of P-gp, and is helpful to elucidate the stereoselective P-gp regulation mechanisms of ginsenoside Rh2 epimers in vivo from a pharmacokinetic view.

NQO1 is an emerging and promising therapeutic target in cancer therapy. This study was to determine whether the anti-tumor effect of tanshinone IIA (TSA) is NQO1 dependent and to elucidate the underlying apoptotic cell death pathways. NQO1(+) A549 cells and isogenically matched NQO1 transfected and negative H596 cells were used to test the properties and mechanisms of TSA induced cell death. The in vivo anti-tumor efficacy and the tissue distribution properties of TSA were tested in tumor xenografted nude mice. We observed that TSA induced an excessive generation of ROS, DNA damage, and dramatic apoptotic cell death in NQO1(+) A549 cells and H596-NQO1 cells, but not in NQO1(-) H596 cells. Inhibition or silence of NQO1 as well as the antioxidant NAC markedly reversed TSA induced apoptotic effects. TSA treatment significantly retarded the tumor growth of A549 tumor xenografts, which was significantly antagonized by dicoumarol co-treatment in spite of the increased and prolonged TSA accumulations in tumor tissues. TSA activated a ROS triggered, p53 independent and caspase dependent mitochondria apoptotic cell death pathway that is characterized with increased ratio of Bax to Bcl-xl, mitochondrial membrane potential disruption, cytochrome c release, and subsequent caspase activation and PARP-1 cleavage. The results of these findings suggest that TSA is a highly specific NQO1 target agent and is promising in developing as an effective drug in the therapy of NQO1 positive NSCLC.