Search

Ceramic thermal barrier coatings (TBCs) with high toughness and low thermal conductivity are important for developing aero engines with high thrust‐to‐weight ratio and thermal efficiency. In this work, the properties of tantalate Y1/6Yb5/6TaO4 (YYT) were optimized by introducing 8 wt.% yttria‐stabilized zirconia (8YSZ), synthesized using spark plasma sintering, as a second‐phase ceramic. The highest toughness (3.57 MPa m1/2) of the YYT/8YSZ composite ceramics was due to multiple toughening mechanisms. The underlying mechanisms of these processes were revealed based on the microstructures and residual stress of the YYT/8YSZ composite ceramics. A shift from an intergranular fracture to a transgranular fracture was caused by the difference between soft‐grain YYT and hard‐grain 8YSZ, which consumed the fracture energy. Furthermore, the formation of microcracks, crack deflection, bridging, and branching were analyzed based on the differences in Young's moduli and thermal expansion coefficients of YYT and 8YSZ. Internal defects and weak connections between the YYT and 8YSZ grains reduced the thermal conductivity of the composites until it reached its lowest value at 1.4 W m−1 K−1. The studied toughening mechanisms could be applied to various composites. Moreover, herein, we provide a new strategy to design and synthesize TBCs with enhanced performance. [ABSTRACT FROM AUTHOR]

This perspective outlines the research directions of ferroelastic rare‐earth (RE) tantalates (RETaO4), which have been studied as multifunctional thermal/environmental barrier coatings (T/EBCs) with working temperatures above 1600°C. Ferroelastic RETaO4 ceramics exhibit several distinct features, including the reversible second‐order ferroelastic phase transition, high toughness, low thermal conductivity, low oxygen ion conductivity, and adjustable thermal expansion coefficients. This perspective provides a concise summary of the research progress on tantalate coatings synthesized via air plasma spraying and electron beam physical vapor deposition. The service performance of tantalate coatings is typically evaluated through thermal fatigue and shock measurements. Uncovering the failure mechanisms and understanding influencing factors are key aspects for future studies. In this regard, establishing the synthesis‐structure‐property relationship of RETaO4 coatings is essential. This brief perspective can serve as a guide for future work on RETaO4 coatings and further advancements in their applications across various fields, including aviation engines and gas turbines. [ABSTRACT FROM AUTHOR]

Effect of B site doping on structural, thermophysical, and mechanical properties of AlNbxTa1‐xO4 ceramics obtained by solid‐phase sintering were investigated in this work. Ferroelastic domain structures derived from the reversible second‐order ferroelastic transformation between the tetragonal (t) and monoclinic (m) contribute to improving the high‐temperature fracture toughness of AlNbxTa1‐xO4 ceramics, and the room fracture toughness of AlNb1/2Ta1/2O4 ceramics is 3.4 MPa·m0.5. The brittleness index of AlNb1/2Ta1/2O4 (2.6 μm−0.5) is also lower than AlTaO4, which indicates that has better damage tolerance. Compared with single‐component AlTaO4 and AlNbO4, the AlNb1/2Ta1/2O4 has a lower thermal conductivity due to enhanced phonon scattering caused by mass disorder and lattice distortion effects. Additionally, AlNb1/2Ta1/2O4 has a good match with the coefficient of thermal expansion of ceramic matrix composites (CMCs), and hence, AlNb1/2Ta1/2O4 has a considerable potential to be the candidate material for thermal/environmental barrier coatings (T/EBCs). [ABSTRACT FROM AUTHOR]

Summary: Due to the infrequency of essential thrombocythemia (ET) in children, little is known about its pathophysiological mechanism. To learn about the clinical and molecular features of Chinese children with ET, we retrospectively analysed 40 children with ET in a single center from 2015–2021. More than half of the children (51.3%, 20/39) were asymptomatic at diagnosis. Nearly half of the children (48.7%, 19/39) had microvascular symptoms, including headache, dizziness, stomachache, and paresthesia. Only two cases experienced vascular events. The proportion of children with typical "driver gene mutations" (i.e., JAK2 p.V617F, CALR exon 9, or MPL exon 10 mutation) was low (12.5%, 5/40). The equivalent ratio of children carried atypical driver gene mutations; however, 30 (75%) patients did not harbour driver gene mutations. Children carrying JAK2 p.V617F had lower platelet count (938 × 109/L vs. 1654 × 109/L, p = 0.031) compared to those without driver gene mutations. Cases harbouring typical driver mutations had higher median WBC counts than those without driver gene mutations (15.14 × 109/L vs. 8.01 × 109/L, p = 0.015). Compared to those without driver gene mutations, cases carrying typical and atypical driver gene mutations were both younger (median ages were 12, 6, and 7 years old, respectively; p = 0.023). The most prevalent non‐driver gene mutations and those mutations with prognostic significance in adult counterparts were less common in children with ET compared to adults with ET. [ABSTRACT FROM AUTHOR]

Tobacco (Nicotiana tabacum L.) is an economically important crop worldwide. Root‐knot nematodes (RKNs) are responsible for yield losses in tobacco and other crops, such as tomato, potato, peanut, and soybean. Therefore, screening for resistance genes that can prevent RKN infestation and the associated damage is crucial. However, there is no report of cloning tobacco RKN resistance genes to date. Here, we cloned the tobacco RKN resistance gene NtRk1 from the resistant variety TI706, using rapid amplification of cDNA ends. NtRk1 has high homology with other RKN resistance genes (CaMi in pepper, Mi‐1.1 and Mi‐1.2 in tomato). Under normal conditions, NtRk1 was barely expressed in the roots; however, following RKN infection, its expression level rapidly increased. Overexpression of NtRk1 in the susceptible cultivar "Changbohuang" enhanced its resistance to Meloidogyne incognita, while RNA interference of NtRk1 in the resistant cultivar K326 resulted in its susceptibility to M. incognita. Moreover, compared with resistant variety K326, we found the salicylic acid and jasmonic acid contents of RNAi plants decreased after inoculation with M. incognita, and confirmed that the function of NtRk1 is related to these phytohormones. These findings indicate that NtRk1 is an RKN resistance gene, which is abundantly expressed in response to RKN infection and may enhance host defense responses by elevating salicylic acid and jasmonic acid levels. [ABSTRACT FROM AUTHOR]

Background and purpose: Previous studies have reported the association between frailty and stroke or Alzheimer's disease (AD). However, the causality remains unclear. The aim of the present study was to evaluate whether genetically predicted frailty is associated with the risk of stroke or AD by a Mendelian randomization (MR) study. Methods: Genetic variants associated with the frailty index (FI) were obtained from a large genome‐wide association study (GWAS). Summary‐level data for stroke and AD were adopted from the corresponding large GWAS of individuals of European ancestry. The inverse variance weighted method was used for estimating causal effects. Multivariable analysis was performed for further adjustment. Results: The present MR study indicated a suggestive association between genetically predicted FI and a higher risk of any stroke (odds ratio 1.360, 95% confidence interval 1.006–1.838, p = 0.046). Regarding the subtypes of stroke, genetically predicted FI was associated with a higher risk of large artery atherosclerosis stroke (LAS) (odds ratio 2.487, 95% confidence interval 1.282–4.826, p = 0.007). No causal links were identified between genetically predicted FI and any ischaemic stroke, intracranial haemorrhage, cardioembolic stroke, small artery stroke, AD or AD‐by‐proxy. Multivariable MR analysis indicated that the association of genetically predicted FI with LAS was attenuated after adjustment for inflammatory bowel disease (p = 0.114). Conclusions: The MR study suggested that genetically predicted FI may be associated with an increased risk of any stroke. Subgroup analysis indicated a suggestive association between genetically predicted FI and the risk of LAS. The underlying mechanisms need further investigation. [ABSTRACT FROM AUTHOR]

A new family of ceramic environmental/thermal barrier coating (E/TBC) materials, that is, ATa2O6 (A = Co, Ni, Mg, Ca), for high‐temperature applications, are investigated and reported in this study. We focus on the synthesis and features of crystal structures, and on the mechanical and high‐temperature properties. ATa2O6 oxides have an extraordinary phase stability (up to 1300°C), and their thermal expansion coefficients (6.2–7.3 × 10−6 K−1) match those of SiC fiber‐enhanced SiC ceramic matrix composites (3–7 × 10−6 K−1). Their low thermal conductivities (min: 1.15 W·m−1·K−1) root in the slow phonon spreading speed and fierce phonon‐phonon scattering process, and they will provide exceptional thermal insulation. Moreover, their hardness (5.6–8.8 GPa), toughness (1.4–1.9 MPa·m1/2), and moduli (100–210 GPa) have good comparability with current E/TBCs. We propose the 33CaO‐9MgO‐13AlO1.5‐45SiO2 (CMAS) corrosion mechanisms of ATa2O6 ceramics, and their robust CMAS resistance relies on the phase stability of CaTa2O6 oxides. The excellent high‐temperature properties ensure that ATa2O6 can be used as E/TBCs to provide thermal insulation and CMAS corrosion protection. [ABSTRACT FROM AUTHOR]

Fast clearing of a short‐circuit fault is vital to increase the transmission capacity of power grid transmission lines and improve the transient stability of a power system. A fast vacuum circuit breaker (FVCB) is a good candidate to realize quick elimination of a short‐circuit fault. The original contribution of this paper is to present the design of a 72.5 kV single‐break FVCB and its verification of short‐circuit breaking performance. A specially designed 72.5 kV vacuum interrupter, with floating shields and reduced mass of moving components, was developed. An electromagnetic repulsion actuator was used to provide a high initial opening speed, V1, of 5 m/s over half of the full‐contact gap and a relatively low average opening speed, V2, of 1.59 m/s in the full contact gap of 30 mm. The high‐designed V1 and low‐designed V2 were achieved with the aid of a deliberately designed oil buffer. The opening and closing time of the designed 72.5 kV FVCB was 1.2 ± 0.04 ms and 18 ± 0.20 ms respectively. The terminal fault test duty of T100s(b), carried out on the 72.5 kV FVCB, demonstrated both the 40 kArms and 80 kArms short‐circuit current breaking performance. The short‐circuit current breaking arcing time windows of FVCB, including the minimum arcing time, the maximum arcing time, and the middle arcing time, was verified to fulfill the requirement of the international standard, IEC 62271‐100 2017, and the Chinese standard, GB/T 1984–2014, both for the 40 kArms and 80 kArms switching cases, respectively. Further development of the 72.5 kV single‐break FVCB would benefit the development of ultra‐ or extra‐high voltage FVCBs by reducing essential numbers of series‐connected breaking units. [ABSTRACT FROM AUTHOR]

Previous studies mainly focused on the behaviours of single‐break vacuum circuit breakers (VCBs) in switching capacitor banks. The prestrike characteristics of double‐break VCBs subjected to axial magnetic fields (AMFs) and transverse magnetic fields (TMFs) in capacitive making operations, to find a proper structure of double‐break VCBs for capacitive switching are experimentally investigated here. Special attention is given to the prestrike gap, inrush current interruption, prestrike voltage, prestrike electric field strength and erosion on contact surfaces of double‐break VCBs. The results show that the 50% prestrike gap d50 and the scatter in prestrike gaps are significantly reduced by nearly 50% by the TMF double‐break VCB compared with the AMF double‐break VCB. The 50% prestrike arcing time ta50 of the TMF double‐break VCB can be reduced by 37.0% compared with the AMF double‐break VCB. The voltage distribution ratio between two vacuum interrupters (VIs) is more balanced in the TMF double‐break VCB (6:4) than in the AMF double‐break VCB (7:3) when prestrike occurs. The TMF double‐break VCB can reduce the erosion caused by inrush currents on contact surfaces compared with the AMF double‐break VCB. In switching capacitor banks, the TMF double‐break VCB is superior to the AMF double‐break VCB. [ABSTRACT FROM AUTHOR]

The partial factor method is widely employed as a design approach for structural reliability and serves as a crucial foundation for structural design codes. However, in practical applications, this method has gradually revealed shortcomings, such as issues with generality and insufficient precision in reliability control. In this article, an improved design value method for the bearing capacity design of steel plate strengthened RC beams was established. Additionally, considering the impact of the live‐to‐dead load effect ratio on the partial safety factor of resistance, a simplified expression for the ultimate limit state design of bearing capacity was proposed. The results show that the reliability index calculated using the partial factor method for the bearing capacity of steel plate strengthened RC beams has a significantly larger relative error. In contrast, the reliability indexes calculated based on the improved design value method are all greater than the target reliability index, ensuring the requirements of reliability design and providing a higher degree of precision in reliability control. [ABSTRACT FROM AUTHOR]

Gliomas are the most common and primary tumors of the central nervous system in adults. Temozolomide (TMZ) is the main drug used to treat glioma; however, prognosis remains poor for most patients. Glioma stem cells (GSCs) are thought to enable glioma initiation and evasion from immune surveillance; their immunogenicity can be determined by expression of major histocompatibility complex (MHC)-I. The present study investigated the effect of TMZ on MHC-I expression in GSCs. Glioma spheres were cultured in serum-free medium containing epidermal growth factor, basic fibroblast growth factor, and B27; MHC-I expression was detected by immunocytochemistry, quantitative real-time PCR, and flow cytometry. Nuclear factor (NF)-κB expression in glioma stem cells was detected by Western blot. TMZ enhanced MHC-I expression in GSCs, and NF-κB was activated. TMZ treatment increased MHC-I expression via modulation of NF-κB signaling in GSCs. In addition to being a chemotherapeutic agent, TMZ may also serve as an immunomodulatory agent in the treatment of glioma patients. [ABSTRACT FROM AUTHOR]

In this study, the domain of attraction is further enlarged for delta operator systems subject to actuator saturation by considering semi‐global stabilisation with guaranteed regional performance. An original feedback law is designed to guarantee certain close‐loop performance in a fixed region which is a compact subset of the null controllable region. Some fixed regions that cover compact subsets of the null controllable region are obtained by a finite sequence of state feedback laws. The union of all obtained fixed regions is the final domain of attraction for the delta operator systems with actuator saturation. A numerical example is provided to illustrate the effectiveness of the proposed techniques. [ABSTRACT FROM AUTHOR]

Coal gangues i a solid waste during the coal mining process and the accumulation of coal gangue will harm the environment. Therefore, solid waste utilization of coal gangue is required to reduce the environmental damage. In this paper, cordierite ceramics are successfully prepared via a solid‐phase sintering using coal gangue, Al2O3, and MgO as raw materials. The effects of sintering temperatures on the microstructures, phase stability, and thermal properties of ceramics are investigated. The results show that the properties of cordierites prepared at 1200°C are close to those of prepared by the traditional method, and the synthesized ceramics have thermal expansion coefficients (TECs) and conductivity of 4.1–10−6 K−1 and 1.72 W·m−1 K−1 at 900°C, respectively. The sample prepared at 1200°C has good wear resistance (η) with a wear resistance coefficient of 0.507, and an excellent thermal shock resistance, which can withstand 15 times of cold and hot shocks at 1100°C without any cracks on the surface. This study systematically elucidates the thermal/mechanical properties of the synthesized cordierite, and the feasibility of using coal gangue as raw materials prepared cordierite ceramics as refractory materials. This work presents an effective solution to mitigate the challenge of coal gangue disposal. [ABSTRACT FROM AUTHOR]