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The ex-service steam tubes containing dissimilar metal weld (DMW) between high Cr ferritic steel T91 and austenitic stainless steel TP347H and the ex-service steam tubes containing DMW between low Cr ferritic steel G102 and austenitic stainless steel TP347H were obtained from coal-fired thermal power plants in China, and their microstructures at the nickel-based weld metal (WM)/ferritic steel interfaces and oxidation characteristics were investigated. After operating for 15,000 h at steam temperature of 541 °C and steam pressure of 17.5 MPa, a G102/TP347H DMW failed along the WM/G102 steel interface, which was a dangerous premature failure mode without obvious plastic deformation. This interfacial failure was attributed to the interaction between oxidation and cracking along the interface, where fracture appeared to be related with the strain concentration at the interface. Oxide notch along the WM/G102 steel interface was the precursor of premature interfacial failure of DMW involving G102. For the DMW involving high Cr ferritic steel T91, ferritic steel side could form a Cr-rich passive film during service and thus would not be further oxidized after operating for 67,000 h at steam temperature of 541 °C and steam pressure of 3.5 MPa. It was concluded that oxidation played a more important role in failure of these DMWs, and retarding the development of oxidation and avoiding the interfacial oxide notch would dramatically improve the service performance of steam tubes containing DMWs.

Background Hepatitis E virus (HEV), which is the leading cause of acute viral hepatitis worldwide, usually causes self-limited infections in common individuals. However, it can lead to chronic infection in immunocompromised individuals and its mechanisms remain unclear. Rabbits are the natural host of HEV, and chronic HEV infections have been observed in rabbits. Therefore, we aimed to investigate potential key genes in HEV chronicity process in rabbits. In this study, both bioinformatics and experimental analysis were performed to deepen the understanding of hub genes in HEV chronic infection in rabbits. Results Ninety-four candidate differentially expressed genes (DEGs) and the pathways they enriched were identified to be related with HEV chronicity. A total of 10 hub genes were found by protein–protein interaction (PPI) network construction. Rabbits of group P (n = 4) which showed symptoms of chronic HEV infection were selected to be compared with HEV negative rabbits (group N, n = 6). By detecting the identified hub genes in groups P and N by real-time PCR, we found that the expressions of MX1, OAS2 and IFI44 were significantly higher in group P (P Conclusions In this work, we presented that MX1, OAS2 and IFI44 were significantly upregulated in HEV chronic infected rabbits, indicating that they may be involved in the pathogenesis of HEV chronicity.

Numerical investigation has been employed to analysis stress distribution in 9Cr/2.25Cr dissimilar welded rotor undergoing welding and heat treatment in order to help optimize structural design. The simulated residual stress on inner and outer cylindrical surface has been validated with experimental data. Distribution and evolution of welding residual stress along weld center line through thickness has also been investigated. It is found that expansion due to martensitic phase transformation in cap weld and shrinkage in nominal HAZ determines the distribution of residual stress on outer cylindrical surface. Meanwhile, expansion caused by martensitic phase transformation and bending effect in annular structure is responsible for the evolution and distribution of through-wall residual stress. Distribution and peak value of through-wall welding residual stress remains after the weld height reaches a certain value (it is about 30% thickness from the inner cylindrical surface in this work), which provides a possibility to predict stress distribution with less time. Meanwhile, post weld heat treatment (PWHT) can release residual stress effectively. Hence, more attention has been paid to as-welded residual stress. Compared with 2.25Cr weld filler, 9Cr weld filler induces greater compressive hoop stress in the newly deposited weld metal and decreases the peak value of tensile hoop stress under it because of greater martensitic phase transformation expansion in cooling process and smaller yield stress at low temperatures.

SmCo7/Co nanocomposite powders were prepared by high-energy ball milling of SmCo5 modified by adding Co and annealed at different temperatures. The phase evolution, microstructure and magnetic properties of the nanocomposite powders were analyzed. The results have shown that the annealing temperature and the addition of Co significantly affected the phase structures and magnetic properties of the powders. The nanocomposite powders were completely composed of the SmCo7 phase and the face-centered cubic Co phase. When annealing the SmCo5 powder at 750 °C, the SmCo7 phase decomposed into Th2Zn17-type Sm2Co17 and CaCu5-type SmCo5 phases with an average grain size of 13.9 nm, and the maximum energy product and remanence had maximum values of 10.51 MGOe and 77.92 emu/g, respectively. However, adding 28 wt% Co effectively prevented growth of the grain (11.5 nm) and enhanced the decomposition temperature (850 °C), resulting in a higher maximum magnetic energy product, coercivity, and remanence. The SmCo7 lattice contracted as Co content increased.

In the work, a 5%Cr weld metal for the 9Cr/2.25Cr dissimilar welded joint was designed. The creep rupture, tensile, and impact behaviors of the weld metal and welded joint were tested and compared with those of the dissimilar welded joint with the 2.25%Cr weld metal. The result showed that the alloy design of the 5%Cr weld metal had a significant effect on reducing the degree of carbon migration at the joint interface. The interfacial creep damage and early failure tendency were reduced greatly. V and Nb in combination with N were added to enable creep strength at elevated temperatures by the formation of MX particles. Creep rupture tests at 540 °C showed good agreement with the alloy design, and no failures were observed in the weld metal for long-term cross-weld creep specimens, indicating that the newly designed 5%Cr weld metal was of adequate creep strength for use with dissimilar welded joint. The excellent tensile strength and adequate toughness showed good agreement with the rationality of tempering parameters.

The following study investigated the strain-induced phase transformation in metastable austenitic 301 stainless steels via an ultrasonic shot peening treatment (USP) for 5 to 30 minutes. Following the USP, the microhardness increased to a depth of 400 μm and from 200 to 400 HV. The deformed grains and the phase transformation were monitored via X-ray diffraction and electron backscattered diffraction analysis. The grain evolution was studied via transmission electron microscopy. Approximately 500 nm α′-martensite grains formed in the top-most region after 5 minutes of the USP treatment. The grains were then further refined to ~ 100 nm when the peening time increased to 10 and 15 minutes. The grains refined down to tens of nanometers after the specimen was treated for 30 minutes, where the phases were composed of α′-martensite (~ 50 nm). There was a mixture of austenite with α′-martensite (~ 25 nm). The grain refinement and the phase transformation of austenite to α′-martensite during ultrasonic shot peening were systematically investigated.

Welding was successfully used in the fabrication of low pressure steam turbine rotors for nuclear power plants. In this paper, the local brittle zone of the welded joint in NiCrMoV steel with heavy section was investigated by cross-zone fracture toughness test and the effect of martensite–austenite constituent in the simulated reheated zone of welds with different second peak temperature on toughness was analyzed. The results showed that the crack propagated in unstable manner in the reheated zone of welds where the martensite–austenite constituent promoted the initiation and propagation of the crack. The fine structure of martensite–austenite constituent contained retained austenite, martensite, and martensite–austenite mixture microstructure. The impact toughness deteriorated drastically in the incomplete phase transition zone for the simulated reheated zone of welds related to the formation of mixture microstructure in which large blocky martensite–austenite constituent at prior austenite grain boundaries and inside the grains were distributed in the shape of network.

The benefits of outdoor play for children’s well-rounded development are maximized when children experience enjoyment and, at the same time, gain physical, motor, cognitive, and social-emotional competence. This study examined the quality of outdoor play in Chinese kindergartens, the dominant form of full-day early childhood education program serving children aged from 3 to 6 years in China. The Outdoor Play Rating Scale was used to study the quality of the provision for children’s outdoor play. A total of 174 classrooms from 91 kindergartens in Zhejiang Province were included in the study. A stratified random sampling procedure was used to select kindergartens and classrooms. Results indicated that there was inadequate opportunity for outdoor play, including free play, as well as low level of physical activity by children. We found significant differences in quality of outdoor play across kindergartens in different locations (urban/non-urban areas). Recommendations were provided to practitioners in the discussion that primarily emphasized addressing the need to increase opportunities for children’s access to a wide range of outdoor activities and to improve teachers’ professional competencies in organizing quality outdoor activities for children. Implications for policymakers include the need to narrow the gap in the quality of outdoor environments in kindergartens so that children’s play is supported in ways that will enhance children’s early development and learning.

The coal hydrogenation reaction process is simply considered as three steps. In the first step, the smaller molecules associated with coal structure units are released as some gases and water in the condition of solvent and heating. In this step, some weaker bonds of the coal structure units are ruptured to form free radicals. The radicals are stabilized by hydrogen atoms from donor solvent and/or H2. In the second step, chain reaction occurs quickly. In the process of chain reaction, the covalent bonds of coal structure units are attacked by the radicals to form some asphaltenes. In the third step, asphaltenes are hydrogenated form more liquids and some gases. In coal liquefaction, the second step of coal hydrogenation reaction should be controlled to avoid integration of radicals, and the third step of coal hydrogenation should be accelerated to increase the coal conversion and the oil yield. A new concept of coal liquefaction process named as China direct coal liquefaction (CDCL) process is presented based on the mechanism study of coal liquefaction.

The maize (Zea mays L.) CRINKLY4 (CR4) gene encodes a serine/threonine receptor-like kinase that controls an array of developmental processes in the plant and endosperm. The Arabidopsis thaliana (L.) Heynh. genome encodes an ortholog of CR4, ACR4, and four CRINKLY4-RELATED (CRR) proteins: AtCRR1, AtCRR2, AtCRR3 and AtCRK1. The available genome sequence of rice (Oryza sativa L.) encodes a CR4 ortholog, OsCR4, and four CRR proteins: OsCRR1, OsCRR2, OsCRR3 and OsCRR4, not necessarily orthologous to the Arabidopsis CRRs. A phylogenetic study showed that AtCRR1 and AtCRR2 form a clade closest to the CR4 group while all the other CRRs form a separate cluster. The five Arabidopsis genes are differentially expressed in various tissues. A construct formed by fusion of the ACR4 promoter and the GUS reporter, ACR4::GUS, is expressed primarily in developing tissues of the shoot. The ACR4 cytoplasmic domain functions in vitro as a serine/threonine kinase, while the AtCRR1 and AtCRR2 kinases are not active. The ability of ACR4 to phosphorylate AtCRR2 suggests that they might function in the same signal transduction pathway. T-DNA insertions were obtained in ACR4, AtCRR1, AtCRR2, AtCRR3 and AtCRK1. Mutations in acr4 show a phenotype restricted to the integuments and seed coat, suggesting that Arabidopsis might contain a redundant function that is lacking in maize. The lack of obvious mutant phenotypes in the crr mutants indicates they are not required for the hypothetical redundant function.