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Stress corrosion crack (SCC) in pipelines directly affects the long-term safety service and has a major impact on the continuity of oil and gas delivery. The near-neutral pH SCC propagation process has been widely reported in the past decades, while the crack initiation mechanism is rarely studied in-depth. Here, the crack initiation behavior of ×60 pipeline steel under different electrochemical potential levels was investigated by interrupted slow strain rate tensile testing (SSRT) and microstructural characterization. The experimental results show that the SCC initiation is dominated by hydrogen-facilitated anodic dissolution (AD) under the open circuit potential (OCP) environment, while it is by the hydrogen embrittlement (HE) under −1.1 and −1.2 VSCE cathodic potentials. All the SCC cracks in ×60 pipeline steel show transgranular features, pathing through the grains in different crystallographic orientations, which showed dependence on the electrochemical potential of the steel: initiation via slip-enhanced dissolution of {110}//ND or {112}//ND texture under OCP environment, but mostly by quasi-cleavage cracking of {100}//ND texture under −1.1 and −1.2 VSCE cathodic potentials.

X80 steel plays a pivotal role in the development of oil and gas pipelines; however, its welded joints, particularly the heat-affected zone (HAZ), are susceptible to stress corrosion cracking (SCC) due to their complex microstructures. This study investigates the SCC initiation mechanisms of X80 steel welded joints under practical pipeline conditions with varying levels of cathodic protection. The SCC behaviors were analyzed through electrochemical measurements, hydrogen permeation tests, and interrupted slow strain rate tensile tests (SSRTs) conducted in a near-neutral pH environment under different potential conditions (OCP, −1.1 VSCE, −1.2 VSCE). These behaviors were influenced by microstructure type, grain size, martensite/austenite (M/A) constituents, and dislocation density. The sub-zones of the weld exhibited differing SCC resistance, with the fine-grain (FG) HAZ, base metal (zone), welded metal (WM) zone, and coarse-grain (CG) HAZ in descending order. In particular, the presence of coarse grains, low dislocation density, and extensive M/A islands collectively increased corrosion susceptibility and SCC sensitivity in the CGHAZ compared to other sub-zones. The SCC initiation mechanisms of the sub-zones within the X80-steel welded joint were primarily anodic dissolution (AD) under open-circuit potential (OCP) condition, shifting to either hydrogen-enhanced local plasticity (HELP) or hydrogen embrittlement (HE) mechanisms at −1.1 VSCE or −1.2 VSCE, respectively.

The strain-induced martensitic transformation (α′-martensite) and residual stress (RS) introduction in the gradient nanostructured (GNS) austenitic stainless steel have been extensively reported in the last three decades, however, their correlation is still unclear. Here, the XRD, EBSD, ECCI and TEM were used to study the RS distribution and martensite behaviors in a GNS SS304 fabricated by ultrasonic surface nanocrystallization modification. We found the non-linear relationship between the magnitude of RS and the fraction of α′-martensite due to the role of α′-martensite in the development of type II intergranular RS. The maximum compressive RS of about 1,244 MPa was obtained as the γ-austenite and α′-martensite phases were each at approximately 50 %. Otherwise, the RS would decrease with the second phase fraction. The developed maximum compressive RS arises from the α′-martensite that formed directly from the γ-austenite. By contrast, the RS from other deformation structures, i.e., α′-martensite produced by γ → ε → α′, ε-martensite, nanotwin and dislocations, is relatively low. The current study classified the correlation of RS and the role of martensite for the first time, which may inspire new approaches for improving the fatigue properties of materials by controlling the phase fraction.

Abstract Although the functions of most protein effectors secreted by fungi are not predictable, they are known to modulate host immunity and facilitate infection. Fusarium graminearum is one of the 10 most abundant plant pathogenic fungi worldwide. To date, few effector proteins secreted by F. graminearum have been identified. In this study, we screened a putative effector protein Fg62 from proteins that contain signal peptides and unknown functional domains in F. graminearum secretome. Fg62 expression was highly upregulated during the early stages of F. graminearum infection, and its deletion reduced F. graminearum virulence in wheat and soybean. Transient expression of Fg62 or the recombinant protein led to plant cell death in Nicotiana benthamiana, and the signal peptide of Fg62 was required for cell death activation. Fg62 homologs are distributed in two species of the F. sambucinum species complex, which are also able to induce cell death in N. benthamiana. Fg62 activated plant immunity by increasing the expression of defense-related genes, and the recombinant Fg62 protein induced plant resistance to various pathogens. Overall, our results revealed that the extracellular effector Fg62 contributes to both pathogen virulence and plant immunity induction, providing new avenues for the development of environmentally friendly crop disease control strategies utilizing nonpolluting immune-inducing factors.

Medium-carbon, high-strength steels are widely used in the field of hydrogen energy because of their good mechanical properties, and they can be readily tailored by heat treatment processes such as the normalizing–tempering (N&T) and quenching–tempering (Q&T) methods. The hydrogen embrittlement (HE) susceptibility of a medium-carbon, high-strength steel was investigated utilizing microstructural characterization with scanning electron microscopy (SEM), the electron backscatter diffraction (EBSD) technique, and transmission electron microscopy (TEM). A study was also conducted on the steel’s hydrogen transport behavior as affected by the N&T and Q&T treatments. The steel contained more hydrogen traps, such as dislocations, grain boundaries, lath boundaries, and carbide interfaces, after the Q&T process, which was associated with a lower HE sensitivity when comparing the two treatments. In comparison, the N&T process produced larger-size and lesser-density carbides distributed along the grain boundaries, and this resulted in a relatively higher HE susceptibility, as revealed by the slow-strain-rate tensile (SSRT) tests of the hydrogen-charged steels and by the fractographic study of the fracture surface.

In response to the rapid development of high-performance electronic devices, diamond/Al composites with high thermal conductivity (TC) have been considered as the latest generation of thermal management materials. This study involved the fabrication of diamond/Al composites reinforced with Ti-coated diamond particles using a liquid–solid separation (LSS) method. The interfacial characteristics of composites both without and with Ti coatings were evaluated using SEM, XRD, and EMPA. The results show that the LSS technology can fabricate diamond/Al composites without Al4C3, hence guaranteeing excellent mechanical and thermophysical properties. The higher TC of the diamond/Al composite with a Ti coating was attributed to the favorable metallurgical bonding interface compounds. Due to the non-wettability between diamond and Al, the TC of uncoated diamond particle-reinforced composites was only 149 W/m·K. The TC of Ti-coated composites increased by 85.9% to 277 W/m·K. A simultaneous comparison and analysis were performed on the features of composites reinforced by Ti and Cr coatings. The results suggest that the application of the Ti coating increases the bending strength of the composite, while the Cr coating enhances the TC of the composite. We calculate the theoretical TC of the diamond/Al composite by using the differential effective medium (DEM) and Maxwell prediction model and analyze the effect of Ti coating on the TC of the composite.

Due to corrosion characteristics, there are data scarcity and uneven distribution in corrosion datasets, and collecting high-quality data is time-consuming and sometimes difficult. Therefore, this work introduces a novel data augmentation strategy using a conditional tabular generative adversarial network (CTGAN) for enhancing corrosion datasets of pipelines. Firstly, the corrosion dataset is subjected to data cleaning and variable correlation analysis. The CTGAN is then used to generate external environmental factors as input variables for corrosion growth prediction, and a hybrid model based on machine learning is employed to generate corrosion depth as an output variable. The fake data are merged with the original data to form the synthetic dataset. Finally, the proposed data augmentation strategy is verified by analyzing the synthetic dataset using different visualization methods and evaluation indicators. The results show that the synthetic and original datasets have similar distributions, and the data augmentation strategy can learn the distribution of real corrosion data and sample fake data that are highly similar to the real data. Predictive models trained on the synthetic dataset perform better than predictive models trained using only the original dataset. In comparative tests, the proposed strategy outperformed other data generation methods.

Objective To investigate the effect of superficial X-ray irradiation at different intervals on the expression of collagen in human keloid fibroblasts and extracellular matrix, and to confirm the optimal irradiation interval. Methods The excised keloid tissue was collected and cultured primary human keloid fibroblasts. The third passage cells were used to set up an experimental group and a control group. Intervals (1, 2, 3, 4, 5, 6, 7 days) with superficial X-rays. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot were used to detect the relative expression changes of collagen type Ⅰ and Ⅲ in cells. ELISA was used to detect the changes of type Ⅰ collagen in the extracellular supernatant, and preliminarily verified the optimal irradiation time interval for superficial X-ray therapy of keloids. One-way ANOVA was used to compare superficial X-ray irradiation groups at different intervals with the control group. The proportion of collagen type Ⅰ and type Ⅲ collagen mRNA decrease in each group was tested by independent samples t test. Results Compared with the control group, the expression level of type Ⅰ collagen mRNA in keloid fibroblasts in experimental group after shallow X-ray treatment at different time intervals showed a low peak at an interval of 3 days (t=12.09, P0.05) and the 7-day interval (t=0.66, P>0.05). The expression of type Ⅰ collagen in extracellular supernatant of all experimental groups decreased by ELISA (P

Abstract While conventional chemical fungicides directly eliminate pathogens, plant immunity inducers activate or prime plant immunity. In recent years, considerable progress has been made in understanding the mechanisms of immune regulation in plants. The development and application of plant immunity inducers based on the principles of plant immunity represent a new field in plant protection research. In this review, we describe the mechanisms of plant immunity inducers in terms of plant immune system activation, summarize the various classes of reported plant immunity inducers (proteins, oligosaccharides, chemicals, and lipids), and review methods for the identification or synthesis of plant immunity inducers. The current situation, new strategies, and future prospects in the development and application of plant immunity inducers are also discussed.

Angiotensin-converting enzyme (ACE), a zinc metalloprotein, is a central component of the renin–angiotensin system (RAS). It degrades bradykinin and other vasoactive peptides. Angiotensin-converting-enzyme inhibitors (ACE inhibitors, ACEIs) decrease the formation of angiotensin II and increase the level of bradykinin, thus relaxing blood vessels as well as reducing blood volume, lowering blood pressure and reducing oxygen consumption by the heart, which can be used to prevent and treat cardiovascular diseases and kidney diseases. Nevertheless, ACEIs are associated with a range of adverse effects such as renal insufficiency, which limits their use. In recent years, researchers have attempted to reduce the adverse effects of ACEIs by improving the selectivity of ACEIs for structural domains based on conformational relationships, and have developed a series of novel ACEIs. In this review, we have summarized the research advances of ACE inhibitors, focusing on the development sources, design strategies and analysis of structure-activity relationships and the biological activities of ACE inhibitors.

Fe-20Cr-25Ni-Nb steel is an important material for developing highly compact and efficient nuclear power systems by using the supercritical CO2 Brayton cycle. The in-core materials should possess excellent oxidation resistance in a high-temperature CO2 environment. In this work, a new 20Cr-25Ni-Nb steel with a minor Mo addition was developed, and its oxidation behavior was investigated in a pure CO2 environment at 650 °C under 3.5 MPa. The experimental results show that the oxidation kinetics of the steels followed the parabolic law with the test time, and the oxidation process was controlled by diffusion. The 20Cr-25Ni-Nb steel showed better oxidation resistance after Mo addition, which was attributed to the synergistic effects of Nb and Mo during the oxide scale formation process. In a high-temperature environment, the volatilization of Mo promoted the outward diffusion of Nb, resulting in the formation of an Nb-rich layer at the oxide/metal interface, which slowed the outward diffusion of Fe for the formation of the outermost Fe-oxide layer. Although the volatile nature of Mo at high temperatures promoted the outward diffusion of Nb, the addition of Mo had no significant influence on the overall structure of the oxide scales, which consisted of an outer Cr-rich oxide layer and an inner spinel oxide layer.

The austempered ductile iron (ADI) grinding balls were austenitized at 900 °C for 2 h and then incomplete quenched in a sodium silicate solution for 100 s, after that austempered in an isothermal furnace at 230 °C for 1 h. Different from the two-step austempering process, this process can prepare a two-phase structure through the incomplete quenching stage and austempering stage, so we called it a dual-matrix structure (DMS) two-step austempering. This work aims to investigate the effect of different concentrations of sodium silicate (30 wt.%, 40 wt.%, 50 wt.% and 60 wt.%) as the incomplete quenching medium on the microstructure and properties of ADI. The microstructure, mechanical properties and wear resistance of ADI were analyzed using SEM with EDS, hardness testing (rockwell) apparatus and impact-toughness tester, as well as friction wear testing and impact wear testing. The result shows that the martensite and lower ausferrite phase in the DMS grinding balls gradually transform to lower ausferrite and upper ausferrite with increasing concentration of quenching liquid. As the sodium silicate concentration increased from 30 wt.% to 60 wt.%, the lower ausferrite volume fraction has initially increased and then decreased. DMS two-step austempering with a 40 wt.% sodium silicate produced the grinding balls with lower ausferrite and a small amount of tempered martensite that has the best overall mechanical properties and wear properties, which were suitable for application of large grinding machines. Besides, this work developed a new method to replace the salt bath austempering process, which was environmentally friendly.

Polymer materials with excellent physicochemical and electrical properties are desirable for energy storage applications in advanced electronics and power systems. Here, Al2O3@ZrO2 nanoparticles (A@Z) with a core-shell structure are synthesized and introduced to a P(VDF-HFP) matrix to fabricate P(VDF-HFP)/A@Z nanocomposite films. Experimental and simulation results confirm that A@Z nanoparticles increase the crystallinity and crystallization temperature owing to the effect of the refined crystal size. The incorporation of A@Z nanoparticles leads to conformational changes of molecular chains of P(VDF-HFP), which influences the dielectric relaxation and trap parameters of the nanocomposites. The calculated total trapped charges increase from 13.63 μC of the neat P(VDF-HFP) to 47.55 μC of P(VDF-HFP)/5 vol%-A@Z nanocomposite, indicating a substantial improvement in trap density. The modulated crystalline characteristic and interfaces between nanoparticles and polymer matrix are effective in inhibiting charge motion and impeding the electric conduction channels, which contributes to an improved electrical property and energy density of the nanocomposites. Specifically, a ~200% and ~31% enhancement in discharged energy density and breakdown strength are achieved in the P(VDF-HFP)/5 vol%-A@Z nanocomposite.

The corrosion and stress corrosion cracking (SCC) behaviors of 20#, X60, and X80 pipeline steels in a near-neutral pH environment were investigated by means of electrochemical measurement, immersion test, and interrupted slow strain rate tensile (SSRT) test. The propensity for SCC, as indicated by the stress threshold value for crack initiation, was found to be dependent on the type of steel microstructure. Cracks were initiated in the high-strength steel X80 at a stress less than its yield strength, whereas in the other lower-grade steels, the initiation of cracks occurred after the yielding point. The threshold stress of SCC initiation in the near-neutral pH environment for 20#, X60, and X80 steels were 130.64% σys, 106.79% σys, and 86.92% σys, respectively. The SCC of 20# and X60 were characterized by the formation of transgranular and intergranular cracks, while X80 steel was only by transgranular cracking. The occurrence of corrosion had a great effect on crack initiation and the growth at the later stage. The latter involved hydrogen effects. A correlation between SCC sensitivity and the yield strength of the steel has been identified.

The sucker rod is an extremely important equipment in oil exploitation, but with the deepening and harsh environment of the petroleum well, higher requirements are put forward for the strength and corrosion resistance of the sucker rod. The most commonly used steel for H grade sucker rods is 4330 steel. However, it has characteristics such as high cost and relatively low sulfide stress cracking resistance. Thus, a novel sucker rod steel with a composition of 0.2 wt.% Cu and 1.2 wt.% Ni was designed. Normalizing + tempering (NT) and quenching + tempering (QT) heat treatment were optimized to render the mechanical properties of the novel sucker rod steel to reach the H grade. Additionally, effects of heat treatment on the microstructural evolution and mechanical properties of the novel sucker rod steel were investigated by optical microscope, scanning electron microscope and mechanical property tests. The results showed that the microstructure is tempered sorbite and the mechanical properties reach H grade after NT and QT. Specifically, the tensile strength, yield strength, elongation and impact toughness of NT/QT samples reached 1010.58/1124.37 MPa, 875.93/1042.63 MPa, 15.66/11.59% and ~77.48/~111.69 J/cm2, respectively. Furthermore, the finer and more dispersed carbides were observed in the QT sample, which means that the QT sample had better strength and toughness.

Abstract Background Human saliva is a protein-rich, easily accessible source of potential biomarkers for the diagnosis of oral and systemic diseases. However, little is known about the changes in salivary proteome associated with aging of patients with dental caries. Here, we applied isobaric tags for relative and absolute quantitation (iTRAQ) in combination with multiple reaction monitoring mass spectrometry (MRM-MS) to characterize the salivary proteome profiles of subjects of different ages, presenting with and without caries, with the aim of identifying age-related biomarkers for dental caries. Methods Unstimulated whole saliva samples were collected from 40 caries-free and caries-susceptible young adults and elderly individuals. Salivary proteins were extracted, reduced, alkylated, digested with trypsin and then analyzed using iTRAQ-coupled LC–MS/MS, followed by GO annotation, biological pathway analysis, hierarchical clustering analysis, and protein–protein interaction analysis. Candidate verification was then conducted using MRM-MS. Results Among 658 salivary proteins identified using tandem mass spectrometry, 435 proteins exhibited altered expression patterns in different age groups with and without caries. Of these proteins, 96 displayed age-specific changes among caries-susceptible adults and elderly individuals, and were mainly associated with salivary secretion pathway, while 110 age-specific proteins were identified among healthy individuals. It was found that the age factor caused significant variations and played an important role in both healthy and cariogenic salivary proteomes. Subsequently, a total of 136 target proteins with complex protein–protein interactions, including 14 age-specific proteins associated with caries, were further successfully validated using MRM analysis. Moreover, non-age-specific proteins (histatin-1 and BPI fold-containing family B member 1) were verified to be important candidate biomarkers for common dental caries. Conclusions Our proteomic analysis performed using the discovery-through-verification pipeline revealed distinct variations caused by age factor in both healthy and cariogenic salivary proteomes, highlighting the significance of age in the great potential of saliva for caries diagnosis and biomarker discovery.

The electronic packaging shell, the necessary material for hermetic packaging of large microelectronic device chips, is made by mechanical processing of a uniform block. However, the property variety requirements at different positions of the shell due to the performance have not been solved. An independently developed liquid–solid separation technology is applied to fabricate the diamond/Al composites with a graded distribution of diamond particles. The diamond content decreases along a gradient from the bottom of the shell, which houses the chips, to the top of the shell wall, which is welded with the cover plate. The bottom of the shell has a thermal conductivity (TC) of 169 W/mK, coefficient of thermal expansion (CTE) of 11.0 × 10−6/K, bending strength of 88 MPa, and diamond content of 48 vol.%. The top of the shell has a TC of 108 W/mK, CTE of 19.3 × 10−6/K, bending strength of 175 MPa, and diamond content of 15 vol.%, which solves the special requirements of different parts of the shell and helps to improve the thermal stability of packaging components. Moreover, the interfacial characteristics are also investigated. This work provides a promising approach for the preparation of packaging shells by near-net shape forming.

Nowadays, dental caries is one of the most common oral health problems, affecting most individuals. It has been found that, by remineralizing enamel at an early stage in the formation of enamel caries, teeth can be effectively protected from dental caries. In this work, a peptide with eight repetitive sequences of aspartate-serine-serine (8DSS) is applied as the bio-mineralizer in an in-vivo rat enamel caries model. Nondestructive quantitative light-induced fluorescence-digital (QLF-D) imaging and micro-computed tomography (micro-CT) are used to evaluate the remineralization of enamel carious lesions by measuring the total fluorescence radiance loss of the molar area (Δ Q Total ), acquired using QLF-D imaging, and the mineral density and residual molar enamel volume, acquired using micro-CT. Correlations are explored between Δ Q Total and mineral density (strong correlation, r = 0.8000, p < 0.001) and Δ Q Total and residual molar enamel volume (moderate correlation, r = 0.6375, p < 0.001). Our results demonstrate that 8DSS is a promising in-vivo remineralization agent that exhibits comparable effects to NaF ( p < 0.05), which has been verified using the classical Keyes method. Moreover, the nondestructive QLF-D and micro-CT methods can be combined to quantify the remineralization of enamel carious lesions three-dimensionally in vivo , making them broadly applicable in quantifying hard tissues.

The demands for the connection between thin dissimilar and similar materials in the fields of microelectronics and medical devices has promoted the development of laser impact welding. It is a new solid-state metallurgical bonding technology developed in recent years. This paper reviews the research progress of the laser impact welding in many aspects, including welding principle, welding process, weld interface microstructure and performance. The theoretical welding principle is the atomic force between materials. However, the metallurgical combination of two materials in the solid state by atomic force but almost no diffusion has not been confirmed by microstructure observation. The main theories used to explain the wave formation in impact welding were compared to conclude that caved mechanism and the Helmholz instability mechanism were accepted by researchers. The rebound of the flyer is still a critical problem for its application. With proper control of the welding parameters, the weld failure occurs on the base materials, indicating that the weld strength is higher than that of the base materials. Laser impact welding has been successfully applied in joining many dissimilar materials. There are issues still remained unresolved, such as surface damage of the flyer. The problems faced by laser impact welding were summaried, and its future applications were proposed. This review will provide a reference for the studies in laser impact welding, aiming process optimization and industrial application.