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The present study envisaged the behavior and relevant crack initiation mechanism of super martensitic stainless steel (0Cr13Ni5Mo) at elevated temperature (ET) under very‐high‐cycle fatigue (VHCF). Fractographic analysis revealed that all the VHCF cracks of the failure specimens initiated from the surface and formed fine granular area (FGA) morphology at ET in an absence of vacuum. The initiation characteristic area (ICA) consisted of an initiation site, a relatively smooth area, and the annular continuous FGA. FGA was formed in the peaks and valleys of local microstructures, and the smooth regions connected these peaks and valleys dominated by shear stress. It was observed that the FGA was unevenly distributed on the crack surface related to the local microstructure and below the grain surface relevant to local strain distribution. The stress intensity factor (SIF) and the crack tip plastic zone of the ICA slightly changed with temperature. Highlights: The vacuum environment was no longer necessary for the formation of FGA.FGA was unevenly distributed related to local microstructure and local strain condition.The fatigue cracks' initiation and early propagation were affected by local microstructure. [ABSTRACT FROM AUTHOR]

Studying the recovery of fire-damaged concrete is of huge economic and environmental significance. The recovery of thermal-induced cracks of fire-damaged concrete leads to the recovery of strength after post-fire curing. To identify the crack recovery behavior of fire-damaged concrete after post-fire curing and its relationship with the recovery of strength, in this study, concrete samples exposed to 400, 600, and 800 °C were treated with the post-fire curing process. The compressive strength recovery was investigated, as well as the crack recovery in terms of the crack length. Moreover, the recovery of the cracks was studied and divided into the categories of mortar cracks and mortar-aggregate interfacial cracks. The results indicate that, after being exposed to high temperatures, the interfacial crack was the main type of crack, and it could clearly be recovered by post-fire curing. The recovery of compressive strength mainly resulted from the recovery of interfacial cracks. The findings of this study can provide practical guidance for the application of post-fire curing to the recovery of fire-damaged concrete structures. [ABSTRACT FROM AUTHOR]

A kind of glucose‐derived carbon‐rich silicon oxycarbide (glucose‐SiOC) nanocomposite with excellent electromagnetic wave absorbing performance is obtained via solvothermal method, and then pyrolyzed at high temperature (1300°C and 1400°C) under argon atmosphere. The structural evolutions and the electromagnetic wave absorbing capabilities of the nanocomposites have been systematically investigated. The resultant 3 mol/L glucose‐SiOC ceramic exhibits a heterostructure, in which nanosized glucose‐derived carbon and SiC particles decorate on amorphous SiOC network. Benefitting from the nanosized carbon, SiC particles and the heterostructure attributes, the 3 mol/L glucose‐SiOC ceramic displays a strong electromagnetic wave‐absorbing property. The minimum reflection coefficient of the 3 mol/L glucose‐SiOC ceramic pyrolyzed at 1400°C reaches −27.6 dB at 13.8 GHz. The widest effective absorption bandwidth attains 3.5 GHz in Kμ‐band. This work opens up a novel and simple route to fabricate polymer‐derived ceramics with excellent electromagnetic wave‐absorbing performance. [ABSTRACT FROM AUTHOR]

Within the morphotropic phase boundary region, 0.39PSN-0.13PMN-0.48PT crystals exhibit excellent properties. The dielectric response of poled 〈001〉-oriented 0.39PSN-0.13PMN-0.48PT crystal plates displays non-relaxor behavior with Curie and depolarization temperatures of about 230 °C and 199 °C, respectively, exhibiting high temperature stability of the ferroelectric phase. The saturated polarization-electric field loop of the same plate manifests the switching of domains, with the coercive field of approximately 5.6 kV/cm, indicating stable piezoelectric properties. The out of plane and in plane domain configurations exhibit obvious domain walls. The typical butterfly strain-electric field curve presents a large peak to peak strain value of about 0.59%. The piezoelectric constant is calculated to be about 1670 pC/N from the unipolar stain-electric field curve. [ABSTRACT FROM AUTHOR]

Dewatered sewage sludge was upgraded to hydrochar using hydrothermal conversion in sub- and near-critical water. Three characteristic temperature regimes responsible for the upgrading were identified. Drastic hydrolysis of carbohydrates, amide II or secondary amines occurred at 200 °C while noticeable decarboxylation initiated above 260 °C. Elevated temperature improved porosity but did not induce higher surface area. Aliphatic C was mainly transformed to aromatic hydrocarbon rather than aromatic C–O in subcritical water, whereas COO/N–C O and aromatic C–O were decomposed to carbohydrate C at 380 °C. Below 300 °C, carbon functionalities in hydrochars were thermally stable and faster decomposition of N than C –(C,H) resulted in dramatic decline of N/C. Above 300 °C, C –H was gradually polymerized to aromatic C –(C,H) which was considerably transformed to C –(O,N) and C –H at 380 °C. CaO favored intense destruction of aromatic C–C/C–H, anomeric O–C–O, C –H and C –(O,N) functionalities but introduced more aromatic C–O and O C –O. [ABSTRACT FROM AUTHOR]

Abstract: The ternary ferroelectric ceramics Pb(Yb1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PYN–PMN–PT), in the vicinity of morphotropic phase boundary (MPB) region, have been prepared by a two-step synthetic process. The ternary phase diagram at room temperature has been established based on the XRD data analysis, which exhibits a curved MPB region. The dielectric, ferroelectric and piezoelectric properties have been characterized, indicating the electrical properties can be adjusted regularly by choosing compositions. The Curie temperature T C of ternary system varied from 165 to 370°C. With the increase of PMN content, the piezoelectric coefficients d 33 increase from 373 to 505pC/N, and the coercive field E c decrease from 18 to 6kV/cm. The results show that the PYN–PMN–PT ternary system can be a potential material for high temperature applications. [Copyright &y& Elsevier]

• Radix Bupleuri (RB) or/and Radix Astragali (RA) extracts ameliorated the growth performance of chronic heat stressed broilers during d 15–42. • The RB or a blend of RB and RA extracts decreased pro-inflammatory cytokines expression in the intestine of chronic heat stressed broilers. • The RB or/and RA extracts increased hepatic antioxidant capacity in chronic heat stressed broilers. The Radix Bupleuri (RB) and Radix Astragali (RA) extracts have anti-inflammatory and antioxidant functions in humans. To determine whether RB and RA extracts had these functions in chronic heat-stressed broilers, 560 15-day-old male broilers were assigned to 7 groups of 8 replicates each (10 birds per replicate), and were under following conditions: 36 °C for 8 h (09:00-17:00) and 30 °C for the remaining time. The broilers were fed the basal diet (control) or the basal diet supplemented with 200 or 400 mg/kg RB extracts (RB200 or RB400), 600 or 800 mg/kg RA extracts (RA600 or RA800), RB200 plus RA800 (RB200-RA800), or RB400 plus RA600 (RB400-RA600) for 28 days. The RB extracts contained 40.1 mg saikosaponins/g, and RA extracts contained 80.0 mg Astragalus polysaccharide/g. Dietary inclusion of RB or/and RA extracts increased (P < 0.05) body weight (BW) of broilers on d 42 and body weight gain during d 15-42. The RB200 and RA800 combination had an additive effect on the BW of broilers when compared to RB200 or RA800 individuals. Thus, the control, RB200, RA800, and RB200-RA800 groups were selected to investigate this additive effect. On d 42, RA800 or RB200-RA800 supplementation decreased (P < 0.05) the mRNA abundance of interleukin (IL) -1 , IL-6 , and tumor necrosis factor-alpha in the jejunum of broilers as compared to the control, whereas no significance was observed in these indices between RA800 and RB200-RA800 treatments. When compared to control, RB200, RA800, or RB200-RA800 supplementation decreased (P < 0.01) malondialdehyde concentration, RA800 or RB200-RA800 supplementation increased (P < 0.05) manganese-containing superoxide dismutase (MnSOD) activity, and RB200 or RB200-RA800 supplementation increased (P < 0.04) catalase (CAT) activity in the liver on d 42. Dietary inclusion of RB200, RA800, or RB200-RA800 increased the mRNA expression of hepatic MnSOD and CAT on d 42. Hepatic CAT activity and the mRNA abundance of MnSOD and CAT were higher (P < 0.05) in RB200-RA800 treatment when compared to RB200 or RA800 treatment. These results suggested dietary inclusion of RB or/and RA extracts improved the growth performance of broilers exposed to high temperature, possibly due to the reduction of intestinal inflammation and the increase of hepatic antioxidant capacity. [ABSTRACT FROM AUTHOR]

Tensile-strained Ge/SiGe multiple quantum wells (MQWs) were grown on a Ge-on-Si virtual substrate using ultrahigh vacuum chemical vapor deposition on an n+-Si (001) substrate. Direct-bandgap electroluminescence from the MQWs light emitting diode was observed at room temperature. The quantum confinement effect of the direct-bandgap transitions is in good agreement with the theoretical calculated results. The redshift mechanism of emission wavelength related to the thermal effect is discussed. [ABSTRACT FROM AUTHOR]

• Very long life fatigue behavior of TC17 welded joints at 400℃ was investigated. • Intergranular welded pores are responsible for fatigue failure. • The unique facets at 400℃ were discovered for TC17 welded joints. • The formation of facets is related to columnar grain and is driven by shear stress. The very long life fatigue failure mechanism of welded joints for titanium alloy at 400℃ has been investigated. The results show that the welded joint has a nonhomogeneous microstructure. The welded defects are mainly welded pores, and maximum pore sizes are evaluated by statistical methods. The increase in temperature reduces the fatigue strength and changes the shape of S-N curves for the welded joints. Crack initiation is attributed to the existence of welded pores. Crystallographic facets are found around welded pores on the crack initiation zone, and their formation is sensitive to columnar grains and is driven by shear stress at 400℃. [ABSTRACT FROM AUTHOR]

Tensile and fatigue behaviors of a compressor blade titanium alloy TC17 at room and high temperatures (RT and HT) have been investigated up to very high cycle fatigue (VHCF) regime. Compared to RT, the HT tensile strength of TC17 titanium alloy decreases, but the elongation remains basically unchanged at HT. The fatigue S–N curves are changed from single linear mode at RT to bilinear mode at HT owing to the temperature effect, and the failure mode is transformed from the surface and subsurface crack initiations at RT to the surface crack initiation at HT. The brittle oxygen-enriched subsurface (BOES) layer on the specimen surface is responsible for the crack initiation at HT. The failure models of oxide shedding and oxide intrusion are proposed. Dislocation distribution indicates that the fatigue failure at HT is insensitive to the intrinsic material microstructure and is only related to the BOES layer on the specimen surface in the VHCF regime. • Very high cycle fatigue behavior of titanium alloy at room temperature and high temperature was investigated. • The oxide layer on the specimen surface is responsible for the fatigue cracks initiation at high temperature. • The dislocation distribution revealed that the material is insensitive to microstructure at high temperature. [ABSTRACT FROM AUTHOR]

• Mechanical behavior of FGSC at elevated temperature. • Influence of elevated temperature on the properties of HGSC. • Prediction E s and F y of rebar connection at elevated temperature. The performance of the prefabricated concrete (PC) structures at elevated temperature becomes an important focus, once a fire occurs. The failure in fire of fully-grouted sleeve connection (FGSC) that extensively used in PC members will cause serious consequences. To fill this knowledge gap, the present work presents the experimental results of 15 FGSC specimens and 15 single rebar (SR) specimens by static tension. The results show that the mechanical behavior of FGSC specimens at high temperature is affected by the temperature and similar to that of SR. Two types of failure modes appear in the FGSC specimens, namely, rebar tension fracture and bond failure. The bond failure was observed at 600 °C. Based on the test results, the tension constitutive relation curves was established, and the bond strength design of FGSC at elevated temperatures were put forward to avoid the bond failure. A new prediction method for calculating mechanical property of prefabricated rebar connection at elevated temperature is proposed. [ABSTRACT FROM AUTHOR]

• HNT induces the heat-response related TFs LOC_Os03g53340 and LOC_Os10g28340 greatly upregulation in HTS of rice. • Unique SNPs locate on the genes LOC_Os04g55740 , LOC_Os10g38489 , LOC_Os04g51460 , LOC_Os12g08760 and LOC_Os05g26250. • Unique SNPs suppress gene expression and contribute to heat-tolerant characteristics of rice. • Heat-stress enhances cellular respiration, consumes the energy-rich substances, ultimately leading to reduced grain yield. Global warming-associated increases in temperature, particularly at nighttime, are detrimental to rice grain filling, ultimately leading to losses in grain weight. However, the molecular mechanisms associated with grain weight loss in rice exposed to high nighttime temperature stress are poorly understood. To screen the genes and single nucleotide polymorphisms (SNPs) associated with high nighttime temperature stress in rice, a hybrid sequencing strategy was used to analyze the differentially expressed genes and SNPs between two rice coisogenic strains, a heat-tolerant strain (HTS) and heat-sensitive strain (HSS), following short-term extreme high nighttime temperature stress at the first stage of seed ripening. Ultimately, 56 genes were differentially expressed between HTS and HSS. After short-term extreme high nighttime temperature stress, genes involved in photosynthesis, oxidation, and detoxication by glutathione were upregulated in HSS in comparison to HTS, while that of the heat response-related transcription factor genes were significantly upregulated in HTS in comparison to HSS. Unique SNPs located on the genes peroxidase precursor , glutathione S-transferase GSTU6 , glycosyl hydrolases , carboxyvinyl-carboxyphosphonate phosphorylmutase, and prolamin precursor PROLM3 were present in HTS but absent from HSS and showed slight alterations in gene expression between HTS and HSS. The proposed model indicated that high nighttime temperature enhanced cellular respiration, disturbed the oxidant-antioxidant balance, and consumed energy-rich substances, ultimately leading to reduced grain yield in HSS in contrast to HTS. These genes and unique SNPs provide genetic resources for the breeding of heat-tolerant rice varieties, and the model provides insights into the molecular basis of the response of rice to high nighttime temperature stress. [ABSTRACT FROM AUTHOR]

• 1. Very high cycle fatigue behavior of LPBF TC4 was investigated at 400℃. • 2. Crack initiation competitions among defects at different locations was analyzed. • 3. Multiple slip systems activated at HT, even those with low Schmid factors. • 4. The formation of FGA is related to grain refinement caused by strain localization. The crack initiation mechanism of laser powder bed fusion (LPBF) Ti6Al4V was investigated at elevated temperature up to very high cycle fatigue (VHCF) regime. The competition concerning defect location is elaborated using the stress intensity factor range and Z-parameter model. Additionally, localized high stress near the defects is responsible for plastic strain localization in the non-prior α' region, following the grain refinement and fragmentation in the larger grains nearby, which is strongly associated with the formation of microcracks and fine granular area. Meanwhile, the process is facilitated by reducing dislocation resistance and activating multiple slip systems due to high temperature. [ABSTRACT FROM AUTHOR]

The mechanical properties of as-extruded Mg-11Gd-5Y-2Zn-0.7Zr (GWZ1152) alloy were systematically studied with respect to their microstructures at room and high temperatures. It exhibited excellent ultimate tensile strength (UTS) of 365 MPa at room temperature (RT), while it maintained relatively high UTS as the temperatures increased to 250 °C (342 MPa), 300 °C (337 MPa) and 350 °C (278 MPa) with a strain rate of 1.85 × 10−3 s−1. The microstructural characterizations revealed that such outstanding heat resistance is mainly attributed to (i) the fine dynamic recrystallized (DRXed) grains and strongly textured un-DRXed grains, (ii) the block-shaped LPSO phase and the nano-scale β precipitates, (iii) the nano-spaced basal LPSO/SFs. Compared to other heat-resistant Mg alloys, our intrinsic chemistry properties contribute to the superior high-temperature mechanical properties of GWZ1152 alloy. For the deformation modes at RT, the dislocations were mainly generated and accumulated on the block-shaped LPSO, followed by cracking and propagation. At 250 °C and 300 °C, non-basal slip inside the coarse un-DRXed was generated, the cracks and fractures were initiated along the slip trace. The main deformation mechanism of GWZ1152 alloy at 350 °C was grain boundary sliding, cracks usually occurred at grain boundaries. • Mg-11Gd-5Y-2Zn-0.7Zr alloy exhibited excellent ultimate tensile strength at 25 °C, 250 °C, 300 °C and 350 °C. • The deformation modes of the alloys were systematically studied at different temperatures. • The relationship between the deformation modes and mechanical properties were discussed at room and high temperatures. [ABSTRACT FROM AUTHOR]

The behavior of prefabricated concrete (PC) structure after fire is an important and fascinating research topic, and Fully-Grouted sleeve connection (FGSC) is widely used in the PC structures. However, research on the mechanical properties of FGSC after elevated temperature is limited. To fill this knowledge gap, this paper presents the experimental results of 18 FGSCs under static tension after 25 °C–1000 °C. Two types of failure modes are observed, namely rebar tension fracture and bond failure. The post-fire properties, including strength, strain, ductility and elastic modulus are analyzed, and the bond strength and bond-slip are discussed. A certain post-fire tensile properties of FGSC are directly influenced by the exposed peak temperature. Meanwhile, suggestion about the value of k is given to avoid bond failure. Based on the synthesis with other's work, it was found that the deformation performance of half-grouted sleeve connection (HGSC) is greater than that of FGSC. [ABSTRACT FROM AUTHOR]

Abstract: A ceramic ternary system of (1−x−y)Pb(Lu1/2Nb1/2)O3–xPbZrO3–yPbTiO3 (PLuN–PZ–PT) has been prepared by two-step synthetic process and characterized by X-ray powder diffraction and electric measurements. A morphotropic phase boundary (MPB) region has been delimited in the ternary system at room temperature. With the PLuN content increasing, the morphotropic phase boundary region becomes broad as well as the dielectric peak. The best comprehensive piezoelectric properties were achieved at MPB composition 0.42PLuN–0.1PZ–0.48PT, with the piezoelectric coefficients d 33, the Curie temperature T c , the planar electromechanical coupling factor K p , and the remnant polarizations P r being 367pC/N, 360°С, 68% and 35μС/cm2, respectively. The results indicate that the PLuN–PZ–PT ternary ferroelectric material may be a promising candidate for high-power electromechanical transducers that can operate in a large temperature range. [Copyright &y& Elsevier]

Abstract: (0.79− x)Pb(In1/2Nb1/2)O3–0.21Pb(Zn1/3Nb2/3)O3–xPbTiO3 (x =0.23–0.35) ternary ferroelectric system in the form of ceramics have been synthesized. Its structure and properties have been studied by X-ray powder diffraction and electric measurements. A morphotropic phase boundary region has been determined in the composition range of 0.28< x <0.32, where the Curie temperature T C and the rhombohedral–tetragonal phase transition temperature T RT were found to vary from 243°C to 295°C and 145°C to 191°C, respectively, much higher than PMNT and PZNT systems. The compositions within MPB region exhibit excellent piezoelectric properties such as piezoelectric coefficient d 33 >646pC/N, T RT >145°C, T C >273°C and E C >13kV/cm for 0.5PIN–0.21PZN–0.29PT and 0.49PIN–0.21PZN–0.30PT, making the ceramics of this system a promising material for high power and high temperature application. [Copyright &y& Elsevier]

The effect of temperature on tensile behavior, low cycle fatigue, and microstructure evolution considering the damage mechanisms of Cr-based heat-resisting steel was investigated. The results present that significant monotonic and cyclic softening was observed at both room temperature and 630 °C. However, the cyclic softening factor is independent of the strain amplitudes and temperatures. At room temperature, the steady fatigue behavior until 80% fatigue life was presented, by contrast, great changes were offered below 80% fatigue life at 630 °C. this is directly related to the microstructure properties during fatigue tests, where dislocation network, wall, and dynamic recovery were formed, resulting from the dislocation movement, interaction, and annihilation. The density of dislocation and intensity of slip is inversely proportional to the temperature. Besides, a prediction fatigue life model fitted by the quadratic function was established through the hysteresis energy, which can consider the effect of temperature on the different fitting parameters and offer the method to optimize the fatigue behavior of Cr-based steel at different temperatures Unlabelled Image • The low cycle fatigue of 9Cr at room temperature and 630 ℃ were performed to evaluate cyclic behavior and microstructure. • The softening behavior is observed at both temperatures. The higher the temperature, the great the softening behavior. • The dynamic recovery happened due to the dislocations annihilation and low angle boundary disappearance. • The higher the temperature, the lower the density of dislocation and the greater intensity of slip. • A prediction model of low cycle fatigue considering the temperature was constituted and confirmed. [ABSTRACT FROM AUTHOR]

Working service of structural materials at elevated temperatures generally leads to a significant decrease in their fatigue performance, thereby threatening the safety and reliability of engineering structures. In this pursuit, the very high cycle fatigue behavior and the relevant crack initiation mechanism of super austenitic stainless steel 654SMO was comparatively investigated at room temperature (RT) and high temperature (HT, 300 °C). It was found that the heterogeneous microstructure strongly influenced the fatigue failure mechanism, wherein the crack initiation sites transferred from fine grain clusters at the RT to coarse grains at HT. Furthermore, the cross-section of the crack initiation sites revealed that the micro-porosity and accumulative slip bands resulted in the crack originations at RT and HT, respectively. The differences of crack initiation were ascribed to the effect of elevated temperature, which weakened the sensibility of crack initiation to micro-defect in very high cycle fatigue regime. Our study provides new insights in the correlation of high temperature and heterogeneous microstructure, in regards to the crack initiation behavior. Unlabelled Image • Fatigue cracks initiated from the micropores within fine-grain clusters at room temperature due to the micropores shortened the crack initiation process. • Non-uniform microstructures caused strain concentration on the interior of the super coarse grains, where fatigue cracks trend to initiate at high temperature. • High temperature weakened the sensibility of crack initiation to micro-defect in very high cycle fatigue regime. [ABSTRACT FROM AUTHOR]