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The Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) ferroelectric single crystals have been commercially available as important components in medical ultrasound transducers due to their excellent piezoelectric and electromechanical coupling performance. The variation in piezoelectric and dielectric properties of PMN-PT single crystals with ambient temperature is an important application indicator. In this work, the PMN-PT single crystals after direct current poling (DCP) and alternating current poling (ACP) were subjected to the cyclic thermal treatment process. The thermal cycling stability and microstructural changes in PMN-PT single crystals were investigated. The ACP single crystals exhibit a higher dielectric constant ε 33 T / ε 0 (6500–7600) and piezoelectric coefficient d33 (2100–2500 pC N−1) compared to the DCP single crystals (ε 33 T / ε 0 of 4100–5000, d33 of 1200–1300 pC N−1). Under thermal cycling at 60 °C, the DCP and ACP single crystals exhibit good thermal cycling stability after 150 cycles. Microstructural observations show that the domain structure of the DCP single crystals exhibits "staggered domain walls, inhomogeneous domain size, variety of domain structure," while the relatively homogeneous stripe-like domains were observed in the ACP single crystals. After thermal cycling, new fine striped domains appear in both the DCP and ACP single crystals due to the instability of rotated polarization, but the piezoelectric and dielectric properties are not greatly affected. This work provides an intensive understanding of the effects of thermal cycling on the domain structure, which is useful for applications. [ABSTRACT FROM AUTHOR]

Seasonal dynamics in the vertical distribution of leaf area index (LAI) may impact the seasonality of forest productivity in Amazonian forests. However, until recently, fine-scale observations critical to revealing ecological mechanisms underlying these changes have been lacking. To investigate fine-scale variation in leaf area with seasonality and drought we conducted monthly ground-based LiDAR surveys over 4 yr at an Amazon forest site. We analysed temporal changes in vertically structured LAI along axes of both canopy height and light environments. Upper canopy LAI increased during the dry season, whereas lower canopy LAI decreased. The low canopy decrease was driven by highly illuminated leaves of smaller trees in gaps. By contrast, understory LAI increased concurrently with the upper canopy. Hence, tree phenological strategies were stratified by height and light environments. Trends were amplified during a 2015-2016 severe El Niño drought. Leaf area low in the canopy exhibited behaviour consistent with water limitation. Leaf loss from short trees in high light during drought may be associated with strategies to tolerate limited access to deep soil water and stressful leaf environments. Vertically and environmentally structured phenological processes suggest a critical role of canopy structural heterogeneity in seasonal changes in Amazon ecosystem function.

12‐hydroxyeicosatetraenoic acid (12‐HETE), a major metabolite of arachidonic acid, is converted by 12/15‐lipoxygenase and implicated in diabetic retinopathy (DR). Our previous study demonstrated a positive correlation between 12‐HETE and the prevalence of DR. However, reasons for the increased production of 12‐HETE are unclear, and the underlying mechanisms through which 12‐HETE promotes DR are unknown. This study aimed to elucidate the correlation between 12‐HETE and DR onset, investigate potential mechanisms through which 12‐HETE promotes DR, and seek explanations for the increased production of 12‐HETE in diabetes. We conducted a prospective cohort study, which revealed that higher serum 12‐HETE levels could induce DR. Additionally, G protein‐coupled receptor 31 (GPR31), a high‐affinity receptor for 12‐HETE, was expressed in human retinal microvascular endothelial cells (HRMECs). 12‐HETE/GPR31‐mediated HRMEC inflammation occurred via the p38 MAPK pathway. 12‐HETE levels were significantly higher in the retina of mice with high‐fat diet (HFD)‐ and streptozotocin (STZ)‐induced diabetes than in those with only STZ‐induced diabetes and healthy controls. They were positively correlated with the levels of inflammatory cytokines in the retina, indicating that HFD could induce increased 12‐HETE synthesis in patients with diabetes in addition to hyperglycemia. Conclusively, 12‐HETE is a potential risk factor for DR. The 12‐HETE/GPR31 axis plays a crucial role in HRMEC dysfunction and could be a novel target for DR prevention and control. Nevertheless, further research is warranted to provide comprehensive insights into the complex underlying mechanisms of 12‐HETE in DR. [ABSTRACT FROM AUTHOR]

Culvert is an important part of railway, and it is also the most neglected railway equipment in daily maintenance. The deterioration and mechanical performance of culvert structure directly affect the safety and stability of the line. Aiming at the problems of insufficient bearing capacity, excessive settlement, dislocation and durability reduction of heavy haul railway culverts under the condition of speed-up reconstruction, this paper conducts the mechanism analysis of culvert reinforcement with assembled corrugated plate, the performance analysis and sensitivity analysis of culvert reinforcement with key parameters of corrugated plate and the practical engineering application technology of culvert reinforcement with corrugated plate based on the methods of finite element analysis, test detection and engineering application. The results show that the overall stiffness of the culvert structure is significantly improved, the stress and deformation of the culvert roof are significantly reduced, and the reinforcement effect is better after using corrugated plate reinforcement technology. Under the same size condition and compared with the rectangular and triangular corrugated plate structures, the maximum vertical displacement and maximum stress value of the roof span can be reduced by 20% or more after the culvert is reinforced by the circular arc corrugated plate, and the circular arc corrugated plate has better reinforcement effect. Under the combined load of the main force, with the increase of the wave height and wave distance of the corrugated plate, the Mises stress of the corrugated plate decreases gradually, and the Mises stress is inversely proportional to the span of the culvert. The field test results of 16 culverts show that the stress and deformation of culverts with different spans and frame culverts are significantly reduced after corrugated plate reinforcement, and the mid-span deflection and dynamic strain are reduced by more than 40% compared with those before reinforcement. Corrugated plate technology has a good reinforcement effect in the culverts of heavy haul railway. [ABSTRACT FROM AUTHOR]

We prove that for an embedded unstable one-sided minimal hypersurface of the |$(n+1)$| -dimensional real projective space, the Morse index is at least |$n+2$|⁠ , and this bound is attained by the cubic isoparametric minimal hypersurfaces. We also show that there exist closed embedded two-sided minimal surfaces in the 3-dimensional real projective space of each odd index by computing the index of the Lawson surfaces. [ABSTRACT FROM AUTHOR]

Pyrite exhibits considerable potential as an adsorbent in wastewater treatment. However, few pyrite adsorbents are directly obtained from natural pyrite, as most are composite materials that require a complex preparation process. To develop a pyrite-based adsorbent with a simple preparation process, pyrite was processed by calcination at 400, 600, and 800 °C for 4 h and ball-milled into a fine powder. The adsorption properties of the pyrite powder were systematically explored. The calcined pyrite powder was characterized by SEM-EDS and XRD. The results revealed that the pyrite calcined at 600 °C exhibited excellent adsorption properties and was primarily composed of Fe7S8. The optimum conditions for Cr(VI) removal were a temperature of 45 °C, an adsorbent dosage of 1 g, an equilibration time of 60 min, and an initial pH of 3. Moreover, the calcined pyrite powder exhibited excellent reusability, and the Cr(VI) removal rate exceeded 65% after three cycles. The Cr(VI) adsorption on pyrite can be well described by the Freundlich model and pseudo-second-order kinetic equation. The calcination temperature is the main factor affecting the adsorption performance of pyrite. Therefore, the calcined pyrite powder is expected to be an excellent adsorbent for Cr(VI) in the wastewater treatment industry. Pyrite has shown promising development prospects in the field of wastewater purification. However, the preparation of most pyrite-based adsorbents is complicated. Upon high-temperature calcination, pyrite is used in traditional Chinese medicine clinics to promote the healing of fractures. The efficiency and underlying mechanism of Cr(VI) adsorption from water using calcined pyrite was investigated. The adsorbent was prepared using a simple method and exhibited excellent adsorption performance, thus allowing its application in preparing ore-based adsorbents for water pollution treatment. [ABSTRACT FROM AUTHOR]

This paper concerns an inverse problem for fluorescence diffuse optical tomography (FDOT) identifying multiple point targets. The targets are the fluorescent agents. The FDOT process is modeled by two diffusion equations coupled with the source term. Our measured data are the time-domain data, measured at some detection points as the temporal response of the fluorescence intensity to an instantaneous injection of the excitation light from a source point. The peak time, clearly observed in the space-time data, has been used as an index to detect the targets. We introduce an approximate peak time based on an asymptotic analysis, which agrees very well with the peak time obtained by the numerical calculation using typical optical parameters. Then, using approximate peak time and combining it with the bisection method, we propose a mathematically rigorous inversion method for the FDOT. The proposed method is efficient, robust and accurate for identifying locations of the deeply embedded targets. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have recently become popular for energy storage due to their high energy density, storage capacity, and long-term cycle life. Although binders make up only a small proportion of LIBs, they have become the key to promoting the transformation of the battery preparation process. Along with the development of binders, the battery manufacturing process has evolved from the conventional slurry-casting (SC) process to a more attractive solvent-free (SF) method. Compared with traditional LIBs manufacturing method, the SF method could dramatically reduce and increase the energy density due to the reduced preparation steps and enhanced electrode loading. Polytetrafluoroethylene (PTFE), as a typical binder, has played an important role in fabricating high-performance LIBs, particularly in regards to the SF technique. In this paper, the development history and application status of PTFE binder was introduced, and then its contributions and the inherent problems involved in the SF process were described and analyzed. Finally, the viewpoints concerning the future trends for PTFE-based SF manufacturing methods were also discussed. We hope this work can inspire future research concerning high-quality SF binders and assist in promoting the evolution of the SF manufacturing technology in regards to LIBs. [ABSTRACT FROM AUTHOR]