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Adverse childhood experiences (ACEs) have far-reaching consequences on an individual’s physical, mental and social well-being. As the world grappled with the unprecedented challenges of the COVID-19 pandemic, understanding the impact of ACEs on social well-being became more crucial than ever. This study aims to investigate the causal effect of ACEs on perceived social well-being during the pandemic.

An instrumental variable design was carried out on data extracted from the Panel Study of Income dynamic (PSID).

This study found a significant causal link between higher levels of ACEs and diminished social well-being, after controlling COVID-19 exposure and symptom severity. Surprisingly, the findings suggest that COVID-19 exposure and symptom severity had no significant impact on social well-being during the pandemic.

These results underscore the enduring influence of childhood adversity on an individual’s ability to form and maintain healthy social connections, highlighting the need for targeted interventions and support systems that promote resilience and social well-being among individuals with a history of ACEs. As we navigate the postpandemic era, this study emphasizes the importance of addressing the long-lasting effects of childhood trauma to foster a more resilient and supportive society.

Rainy-day savings have been an effective measure for maintaining financial stability in times of emergency. Motivated by the rapid expansion of cryptocurrencies, the present study examines how crypto investments could moderate the beneficial outcomes of rainy-day savings for alleviating financial anxiety during the most recent economic turbulence caused by the COVID-19 pandemic.

The present study carries out multivariate logistic regression with interaction effects on the most recent 2021 cohort data from the National Financial Capability Study (NFCS).

While rainy-day savings relate to less financial anxiety, the effect varies depending on whether an individual has invested in cryptocurrencies. Specifically, this paper finds that crypto investors experience less relief in financial anxiety from rainy-day savings than non-crypto investors. Additionally, crypto investors are more susceptible to financial stressors like job loss and financial fragility, likely due to the financial loss from investing in cryptocurrencies.

The findings highlight the necessity of implementing policies and regulations, such as the newly approved Markets in Crypto-Assets (MiCA) regulation, that could raise people’s awareness of the high-risk nature of cryptocurrencies as well as offering targeted financial education for crypto investors, especially during times of market downturn.

This is the first attempt to study how crypto investments may weaken the benefits of rainy-day savings in reducing financial anxiety. The findings offer new insights into the beneficial outcomes of rainy-day savings for emergencies in light of individual crypto investment backgrounds. Additionally, findings from the present study also contain important implications given the rapid expansion of the cryptocurrency market as well as future economic turbulence.

Robo-advisory has become an increasingly popular asset management tool in recent decades. This paper studies the association between robo-advisor usage and perceived financial satisfaction.

Using data extracted from the National Financial Capability Study 2015 (NFCS2015), the present study carried out a logistic analysis that examines the association between robo-advisory and perceived financial satisfaction. This model also studies the interaction effect of age on this association.

The present study finds that robo-advisor usage is positively correlated with a person’s perceived financial satisfaction after controlling for covariates related to financial literacy and other demographic factors. Moreover, the present study reveals that age moderates the association between robo-advisory usage and financial satisfaction. The results are robust after regressing financial satisfaction on robo-advisory by different age groups.

This paper extends existing literature on robo-advisory by showing that robo-advisory usage relates to a higher level of financial satisfaction. This finding helps understand the rapidly increasing trend of robo-advisory in the financial industry. Moreover, the present study reveals a moderate effect of age on the association between robo-advisory usage and perceived financial satisfaction.

In this paper, we empirically investigate how crypto investments in times of economic downturn would affect credit card usage, a widely used payment method that has a significant impact on individual financial well-being.

We carry out an ordinary least squares regression analysis and an instrumental variable design on data from the most recent National Financial Capability Study 2021 (NFCS2021). The NFCS2021 collects information about various demographic and financial backgrounds of US adults.

We find that crypto investments are associated with a significantly higher likelihood of credit card misuse, as indicated by making only the minim um payments, late payments and using credit cards for cash advances. Meanwhile, social media use is a strong predictor of crypto investments. Results from our analysis are robust after accounting for endogeneity concerns using an instrumental variable design.

Our findings provide new insights into the influence of emerging financial instruments on delinquent credit card behaviors, which can further intensify individual and household financial instability during periods of market stress. Furthermore, our findings underscore the necessity of improving individual awareness of the high-risk characteristics of cryptocurrencies, despite their increasing popularity in the financial marketplace in the current financial marketplace.

This study aims to focus on the heat treatment influence on the corrosion resistance, adhesion of Streptococcus mutans and mechanical properties of CoCrMo alloys manufactured by the selective laser melting (SLM).

CoCrMo alloys were manufactured using the Dimetal-100 machine. X-ray diffraction (XRD), metallographic analysis, scanning electron microscopy (SEM), electrochemical corrosion, Vickers microhardness and tensile tests were used to characterize SLM-produced CoCrMo alloys and compare them with the ones manufactured by casting and with the ASTM F75 standard.

The electrochemical results showed that SLM900 samples had the best corrosion resistance in artificial saliva. The adhesion results showed least propagation and overall quantity of Streptococcus mutans on the SLM900 sample. The microhardness, tensile and yield strength of As-SLM, SLM900 and SLM1200D samples were measured according to the ASTM F75 standard. The elongation of SLM900 was less than 8 per cent, which does not meet the standard specifications. Analysis of the fracture morphology showed that the fracture mechanisms of As-SLM and SLM1200D belong to the quasi-cleavage fracture type, and the mechanical fracture mechanism of SLM900 can be characterized as brittle fracture.

This paper presents the adhesion properties of Streptococcus mutans on the surface of CoCrMo alloys manufactured by SLM and proposes how to regulate the effect of the heat treatment on the corrosion resistance and mechanical properties of CoCrMo alloys manufactured by SLM.

This paper aims to verify whether selective laser melting (SLM) could be used for manufacturing mold with conformal cooling channels and determine whether the mechanical properties development of SLM manufacturing maraging steel mold would be beneficial to improve the quality of mold.

A series of block specimens and cylindrical tensile specimens are manufactured by SLM, and then are heat treated by solution treatment (ST) and solution treatment + aging treatment (ST + AT), respectively. The development of microstructure, microhardness and tensile strength of specimens is investigated. Then, a mold with conformal cooling channels is designed and manufactured by SLM and machined after ST with microhardness decreasing.

The morphology of microstructure varies widely under different heat treatment. The microhardness and tensile strength decrease after ST with cellular structure broken, which is conducive to mechanical finishing for mold to improve surface accuracy. After that, the hardness and strength of the mold increase significantly by AT with the precipitation of Ni3Mo, Fe2Mo and Ni3Ti particles. The maraging steel mold with conformal cooling channels can be manufactured by SLM successfully. And the surface accuracy of mold could be improved easily by machining.

Compared with the traditional mold with simple cooling channels, the mold with conformal cooling channels can be manufactured by SLM directly. The hardness of maraging steel mold manufactured by SLM can be reduced through ST, which is conducive to mechanical finishing for overcoming the defect of low precision of SLM directly manufacturing mold. This provides a new way for manufacturing mold of high quality.

This paper aims to summarize design rules based on the process characteristics of selective laser melting (SLM) and structural optimization and apply the design rules in the lightweight design of an aluminum alloy antenna bracket. The design goal is to reduce 30 per cent of the weight while maintaining the stress levels in the original part.

To reduce weight as much as possible, the titanium alloy with higher specific strength was selected during the process of optimization. The material distribution of the bracket was improved by the topology optimization design. The redesign for SLM was used to obtain an optimization model, which was more suitable for SLM. The component performance was improved by shape optimization. The modal analysis data of the structural optimization model were compared with those of the stochastic lightweight model to verify the structural optimization model. The scanning data were compared with those of the original model to verify whether the model was suitable for SLM.

Structural optimization design for antenna bracket realized the mass decrease of 30.43 per cent and the fundamental frequency increase of 50.18 per cent. The modal analysis data of the stochastic lightweight model and the structural optimization model indicated that the optimization performance of structural optimization method was better than that of the stochastic lightweight method. The comparison results between the scanning data of the forming part and the original data confirmed that the structural optimization design for SLM lightweight component could achieve the desired forming accuracy.

This paper summarizes geometric constraints in SLM and derives design rules of structural optimization based on the process characteristics of SLM. SLM design rules make structural optimization design more reasonable. The combination of structural optimization design and SLM can improve the performance of lightweight antenna bracket significantly.

This review aims to give a critical view of the wheel/rail high frequency vibration-induced vibration fatigue in railway bogie.

Vibration fatigue of railway bogie arising from the wheel/rail high frequency vibration has become the main concern of railway operators. Previous reviews usually focused on the formation mechanism of wheel/rail high frequency vibration. This paper thus gives a critical review of the vibration fatigue of railway bogie owing to the short-pitch irregularities-induced high frequency vibration, including a brief introduction of short-pitch irregularities, associated high frequency vibration in railway bogie, typical vibration fatigue failure cases of railway bogie and methodologies used for the assessment of vibration fatigue and research gaps.

The results showed that the resulting excitation frequencies of short-pitch irregularity vary substantially due to different track types and formation mechanisms. The axle box-mounted components are much more vulnerable to vibration fatigue compared with other components. The wheel polygonal wear and rail corrugation-induced high frequency vibration is the main driving force of fatigue failure, and the fatigue crack usually initiates from the defect of the weld seam. Vibration spectrum for attachments of railway bogie defined in the standard underestimates the vibration level arising from the short-pitch irregularities. The current investigations on vibration fatigue mainly focus on the methods to improve the accuracy of fatigue damage assessment, and a systematical design method for vibration fatigue remains a huge gap to improve the survival probability when the rail vehicle is subjected to vibration fatigue.

The research can facilitate the development of a new methodology to improve the fatigue life of railway vehicles when subjected to wheel/rail high frequency vibration.