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The evolution of the microstructural and mechanical properties of alloy 617B during long-term service on a key-component test platform at 700 °C was systematically investigated. The precipitation behavior and size changes of the M23C6 and γ′ phases were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that carbide M23C6 precipitated in the form of discontinuous particles, plates, or needles at grain boundaries and within grains, while the γ′ phase had a spherical shape and was distributed in a dispersed manner. With prolonged service time, both the M23C6 and γ′ phases gradually coarsened. After 24,000 h of service, the yield strength, tensile strength, and Brinell hardness of alloy 617B significantly increased; however, the impact toughness decreased, accompanied by intergranular embrittlement. The increase in precipitate volume fraction and its contribution to the strength of the alloy were evaluated by a precipitation strengthening model. The coarsening of M23C6 was identified as the main cause of embrittlement. The findings of this study provide important experimental data and theoretical support for the stability of 617B alloys under long-term high-temperature service conditions. [ABSTRACT FROM AUTHOR]

To investigate the mechanical properties and microstructure evolution of P92 steel during long-term service, the operated P92 main steam pipes from the first ultra-supercritical units in China were sectioned into samples representing various service durations and stresses (0# (as-received state, 1# (82,000 h, 67.3 MPa), 2# (85,000 h, 78.0 MPa), and 3# (100,000 h, 80.3 MPa)). Thereafter, a comprehensive assessment of their mechanical properties, including tensile strength, impact, hardness, and creep resistance, as well as a detailed microstructure analysis, was carried out. The effect of stress on the aging of material properties during operation is discussed. The results show that the circumferential stress caused by the increase in the internal steam pressure can significantly promote the creep life consumption of P92 steel, resulting in the degradation of mechanical properties and the expedited aging of the microstructure. The Rp0.2 and Rm of the P92 main steam pipe at room temperature and 605 °C decreased with the service time increase, reflecting the influence of stress in operation, which is expected to be used for the residual life evaluation of P92 steel. The relationship between the impact absorption energy (FATT50), Brinell hardness, and the operating time of P92 operating pipes is non-monotonic, indicating that these parameters are not sensitive indicators of material aging due to stress. The evaluation of performance degradation in P92 operating pipes due to stress-induced aging is not reliably discernible through optical metallography alone. To achieve a thorough assessment, the use of transmission electron microscopy (TEM) is essential. [ABSTRACT FROM AUTHOR]

P92 steel is widely used in ultra-supercritical units due to its excellent high-temperature performance. This paper studies the microstructure of P92 steel steam pipes in three conditions: as-supplied, after 80,000 h of service at 67.06 MPa stress, and after 100,000 h of service at 80.28 MPa stress. After prolonged service, the P92 steel retains its martensitic structure, but the lath width increases and the dislocation density decreases. In addition to M23C6, MX, and Laves phases, Z phase was also observed among the precipitates. The results indicate that the sizes of M23C6 and Laves phases increase with the progression of creep life consumption, with the coarsening rate of Laves phase being significantly higher than that of M23C6. However, the coarsening of MX phase is not evident. Compared to the Laves phase, the formation of the Z phase requires a longer period of time. The precipitation of the Z phase consumes MX carbonitrides, and it has been observed that the Z phase precipitates from the MX phase, with the two phases exhibiting a coexisting state. [ABSTRACT FROM AUTHOR]

Background: The psychosocial impact of dental aesthetics (PIDA) has a significant effect on well-being and quality of life. This study aimed to explore the latent heterogeneous classes of the PIDA among adolescents and investigate the relationships among identified subtypes and sociodemographic variables, the status of left-behind children, and the clinical manifestations of malocclusion. Methods: A cross-sectional study on the PIDA among 1451 adolescents aged 11 to 12 years in elementary schools in a rural area in Guangxi, China, was conducted. The PIDA on adolescents was also investigated via latent profile analysis; each predictor was tested via ordinal logistic regression. Results: Three latent classes for the PIDA were identified: low-risk (48.2%), medium-risk (39.8%), and high-risk (11.9%) groups. There were significant differences among the three latent classes. The results revealed that being female, The duration of maternal employment outside the hometown, the largest anterior maxillary irregularity, the largest anterior mandibular irregularity, and the antero-posterior molar relationship (ORs of 1.737, 1.138, 1.117, 1.157, and OR = 1.242; P < 0.001, < 0.01, < 0.01, < 0.01 and < 0.05, respectively) had significant effects on the PIDA on adolescents. Conclusions: The occlusal features, being female and the duration of maternal employment outside the hometown are risk factors that influence the PIDA on adolescents. This provides an evidence for improving the PIDA status among rural adolescents. [ABSTRACT FROM AUTHOR]

Lanbuzheng (Geum japonicum Thunb. var. chinense Bolle), a plant found in Southwest China, is a traditional Chinese medicine that promotes hematopoiesis and antioxidant functions. Many of its chemical constituents remain unknown, posing challenges both to understanding its pharmacological mechanisms and to conducting quality control research. In this work, ultra‐high performance liquid chromatography coupled with quadrupole Exactive Orbitrap high‐resolution mass spectroscopy was used for profiling the composition of Lanbuzheng. Using positive ion mass spectrometry data enriched from Lanbuzheng extract, feature‐based molecular networking (FBMN) was constructed and associated with Mass2Motifs substructures using MS2LDA. Prediction and validation of unknown constituents of Lanbuzheng using a custom‐built compound library, SIRIUS, and network annotation propagation, achieved a semi‐automated annotation of the molecular network. Based on the custom‐built library comprising 206 compounds and the FBMN clustering results, the constituents in Lanbuzheng primarily include tannins, triterpenes, flavonoids, and phenolics. Using only 65 pre‐identified compounds as references, 210 unknown compounds were annotated in various polarity regions of Lanbuzheng. Results of the current work indicate that molecular networks enable the efficient annotation of compounds in complex systems, laying the groundwork for the preliminary identification of pharmacologically active constituents of Lanbuzheng. [ABSTRACT FROM AUTHOR]

In traditional Chinese medicine, the two commodity forms of Cassiae Semen Raw and Prepared Cassiae Semen, exert different clinical applications, in which Prepared Cassiae Semen is commonly used to treat liver and eye diseases. However, the material basis of Raw and Prepared Cassiae Semen remains unclear due to the limited studies on their overall composition and metabolism in vivo. In this study, an integrated analysis strategy based on ultra‐high‐performance liquid chromatography coupled with quadrupole‐Orbitrap high‐resolution mass spectrometry was established to systematically screen the prototype and metabolite constituents of Raw and Prepared Cassiae Semen. Automatic matching analysis of metabolites was performed on Compound Discoverer software based on the function of predicting metabolites. Using this strategy, a total of 77 compounds in Raw Cassiae Semen and 71 compounds in Prepared Cassiae Semen were identified. Furthermore, in vivo study, 46 prototype components and 104 metabolites from the Raw Cassiae Semen group and 41 prototype components and 87 metabolites from the Prepared Cassiae Semen group were unambiguously or preliminarily identified in mice (plasma, urine, feces, eye, and liver). This is the first study of chemical component analysis and in vivo metabolite profiling of Raw and Prepared Cassiae Semen. [ABSTRACT FROM AUTHOR]

The Laves phase formed during the long-term creep of 9% Cr heat-resistant steels plays an important role in their high-temperature mechanical properties. Detecting and quantifying the Laves phase is one of the main problems in predicting the creep residual life. This study detects and quantifies the Laves phase in various 9% Cr heat-resistant steel samples by anodic polarization. Both T92/P92 samples after creep and 9Cr ferritic martensitic samples after thermal ageing precipitate Laves phase particles, and the content of the Laves phase increases with the service time. Comparing the results obtained by the electrochemical method with those obtained by the traditional SEM observation method, it can be found that there is a similar two-stage linear relationship between the two results in all materials, which is related to the diameter change of Laves phase particles during service. According to the correlation between the Laves phase content and creep time, an extrapolation method for the prediction of the residual creep life is proposed. The results show that the creep life of P92 can be predicted by using the dissolved charge density of the Laves phase with high prediction accuracy. This method has the potential to evaluate the service states of materials and predict the long-term creep life in the industrial field. [ABSTRACT FROM AUTHOR]