Investigation of the Dislocation Density of NiCr Coatings Prepared Using PVD–LMM Technology

Micron-sized coatings prepared using physical vapor deposition (PVD) technology can peel off in extreme environments because of their low adhesion. Laser micro-melting (LMM) technology can improve the properties of the fabricated integrated material due to its metallurgical combinations. However, the microstructural changes induced by the high-energy laser beam during the LMM process have not been investigated. In this study, we used the PVD–LMM technique to prepare NiCr coatings with a controlled thickness. The microstructural changes in the NiCr alloy coatings during melting and cooling crystallization were analyzed using molecular dynamics simulations. The simulation results demonstrated that the transition range of the atoms in the LMM process fluctuated synchronously with the temperature, and the hexagonal close-packed (HCP) structure increased. After the cooling crystallization, the perfect dislocations of the face-centered cubic (FCC) structure decreased significantly. The dislocation lines were mainly 1/6 imperfect dislocations, and the dislocation density increased by 107.7%. The dislocations in the twinning region were affected by the twin boundaries and slip surfaces. They were plugged in their vicinity, resulting in a considerably higher dislocation density than in the other regions, and the material hardness increased significantly. This new technique may be important for the technological improvement of protective coatings on Zr alloy surfaces

Effects of the Laser Micromelting Process Parameters on the Preparation of Micron-Sized FeCrAl Coatings on Zr Alloy Surfaces

Laser micromelting (LMM) technology allows for the remelting of pre-positioned coatings on the surface of a specimen to form a metallurgical bond with the substrate material, significantly improving the coating’s film–base bond. However, the high energy input from the laser modification process can cause severe element diffusion, rendering the coating susceptible to deformation and cracking. This can be mitigated by controlling the laser power, scanning speed, and offset of the LMM process. The temperature and stress fields of the samples in the LMM process were analyzed via finite element simulation. The effects of the LMM process parameters on the coating morphology were analyzed in conjunction with experiments. The results indicated that the laser power significantly affected the morphology of the coating after remelting, and a higher scanning speed was more likely to cause the coating to accumulate stress. Additionally, a smaller offset inhibited crack generation. At a laser power of 30 W, a scanning speed of 1200 mm/min, and a scanning spacing of 0.035 mm, the surface of the coating had no obvious defects and was relatively flat, and the adhesion and corrosion resistance were significantly improved. This study provides valuable guidance for improving the preparation of micron-sized protective coatings on Zr alloy surfaces

Does music intervention relieve depression or anxiety in people living with dementia? A systematic review and meta-analysis

BACKGROUND: This study aimed to summarize the available evidence on music intervention alleviating depression or anxiety in dementia. METHODS: A comprehensive literature search was performed to analyze the effects of music intervention on depression or anxiety. Subgroups were created to explore the effect of intervention period, duration, and frequency on efficacy. The effect size was reported as a mean standardized difference (SMD) with 95% confidence interval (CI). RESULTS: The analysis included 19 articles involving 614 samples. Thirteen studies for relieving depression revealed that, with an increase in intervention period, the efficacy decreased and then increased, whereas with an increase of intervention duration, the effect became better. A weekly intervention is ideal. Seven studies verifying the impact on anxiety relief revealed that the effect of intervention within 12 wk is significant; with an increase of intervention duration, the effect became better. A weekly intervention is ideal. Collaborative analysis showed that long low-frequency interventions are more efficient than short high-frequency interventions. CONCLUSIONS: Music intervention can relieve depression or anxiety in people living with dementia. Weekly short interventions of more than 45 min are effective for emotional regulation. Future research should concentrate on severe dementia and follow-up impact

Nasopharyngeal Carcinoma Burden and Its Attributable Risk Factors in China: Estimates and Forecasts from 1990 to 2050

Nasopharyngeal carcinoma (NPC) is an uncommon and aggressive malignant head and neck cancer, which is highly prevalent in southern and southwestern provinces in China. The aim of this study was to examine the disease burden and risk factors of nasopharyngeal carcinoma in China from 1990 to 2019 and to predict the incidence trends from 2020 to 2049. All data were extracted from the 2019 Global Burden of Disease (GBD) study. Joinpoint regression and age-period-cohort (APC) models were chosen to analyze prevalence trends. The temporal trends and age distribution of risk factors were also analyzed descriptively. Bayesian APC models were used to predict the prevalence from 2020 to 2049. The results indicate a higher disease burden in men and older adults. Their attributable risk factors are smoking, occupational exposure to formaldehyde, and alcohol use. We predict that the incidence will be on the rise in all age groups between 2020 and 2049, with the highest incidence in people aged 70 to 89 years. In 2049, the incidence rate is expected to reach 13.39 per 100,000 (50–54 years), 16.43 (55–59 years), 17.26 (60–64 years), 18.02 (65–69 years), 18.55 (70–74 years), 18.39 (75–79 years), 19.95 (80–84 years), 23.07 (85–89 years), 13.70 (90–94 years), and 6.68 (95+ years). The findings of this study might deserve consideration in China’s NPC prevention and control policy design

Maternal overweight but not paternal overweight before pregnancy is associated with shorter newborn telomere length: evidence from Guangxi Zhuang birth cohort in China

10.1186/s12884-021-03757-xBMC Pregnancy and Childbirth21128