In the realm of abrasive flow machining (AFM), precise finishing and maintaining dimensional accuracy have remained challenging due to non-uniformities in the AFM process and complexities associated with the abrasive media's shear viscosity and wall slip behavior. By addressing these challenges, this study introduces a comprehensive framework, combining theoretical foundations, measurement techniques, and experimental setups. Utilizing capillary flow, a novel compensation strategy is incorporated within the Mooney method to counter entrance pressure drop effects. This enhanced capillary flow method emerges as a promising alternative to the conventional Cox-Merz empirical rule, enabling precise characterization of wall slip behavior and shear viscosity, particularly at elevated shear rates. The abrasive media exhibit a Navier nonlinear wall slip, as highlighted by the Mooney method. Rigorous verification of the proposed methodologies and models against supplemental experiments showcases a high degree of congruence between predicted and observed results, emphasizing their accuracy and broad application potential in AFM. This research illuminates the intricacies of the abrasive media's behavior, accentuating the need for meticulous characterization, and provides a robust foundation for genuine modeling and predictions in material removal within AFM.
Aqueous electrochemical nitroarene reduction reaction using H2O as the sustainable hydrogen source is an emerging technology to produce functionalized anilines. However, the development of low-cost electrocatalysts and the fundamental mechanistic understanding of the selective NO-RR still remain challenging. Herein, self-supporting hierarchical nanosheets consisting of high-density Co9S8/Ni3S2 heterojunctions on Ni foam (Co9S8/Ni3S2-NF) are constructed via an in situ self-template strategy. With combined advantages of high-loading, high surface exposure, efficient conductivity and unique electronic structure of the Co9S8/Ni3S2 interface, the as-prepared Co9S8/Ni3S2-NF exhibits efficient electrocatalytic NO-RR performance, including up to 99.0% conversion and 96.0% selectivity towards aniline, and outstanding functional group tolerance. Mechanistic investigations and theoretical calculations reveal that electron transfer from Ni3S2 to Co9S8 is beneficial for the co-adsorption of H2O and nitrobenzene molecules at the interfacial sites, promoting the formation of active hydrogen and subsequent reduction of nitrobenzene. Additionally, the interfacial charge transfer breaks the symmetry of two active Co sites at the Co9S8/Ni3S2 interface, which markedly reduces the energy barrier for reduction of nitrobenzene to aniline. This work offers a successful example for the interfacial engineering of metal sulfide-based heterojunctions with excellent electrocatalytic nitroarene reduction performance, and also paves the way for the in-depth understanding of the corresponding mechanism.
Objective: Here, we investigated the relationship between social avoidance and depression in college students, explored the mediating roles of loneliness and trust, and the regulatory role of self-esteem, to provide a theoretical intervention approach based on internal mechanisms. Methods: Using a simple random overall sampling method, 1,021 college students were investigated using self-rating depression, social avoidance and distress, loneliness, interpersonal trust and self-esteem scales. Results: There was a significant positive correlation between social avoidance and depression. Loneliness and interpersonal trust played chain-mediating roles between social avoidance and depression. The influence of social avoidance on interpersonal trust was regulated by self-esteem. Specifically, the social avoidance level of the low self-esteem group was more likely to be affected by interpersonal trust issues. Conclusion: Social avoidance not only directly affects college students' depression, it also has indirect effects through interpersonal trust and loneliness. Thus, interpersonal trust and loneliness have chain-mediating effects between social avoidance and depression in college students, and self-esteem regulates the mediation process.
BACKGROUND: Methamphetamine (METH) dependence is a complex and dynamic public health problem. Long-term abuse of METH can increase numerous risks of mental and physical problems. Currently, the methods to reduce METH dependence and improve the withdrawal symptoms are limited and ineffective. Resilience is seen as a multidimensional and dynamic capability to recover or bounce back from stressful events and is also generally considered as a protective factor against mental dysfunction. METHODS: One hundred thirty-four males with METH dependence were consecutively recruited from Huanglong Compulsory Isolated Detoxification Center between 2019 and 2021, of whom 112 were into the group. The Connor-Davidson Resilience Scale (CD-RISC), Self-rating depression scale (SDS), Self-rating anxiety scale (SAS), Barratt Impulsiveness Scale-11(BIS-11), and the Repeatable Battery for the Assessment of Neuropsychological Status (Rbans) were used to evaluate resilience, depression, anxiety, impulsivity, and cognition respectively. RESULTS: The results mainly indicated that high resilience group showed lower SDS, SAS and BIS-11 scores than low resilience group (all p < 0.05). Besides, the total scores of Rbans were higher in high resilience groups than low resilience group (both p < 0.05). Moreover, linear regression results showed that resilience may be influenced by the scores of SDS and SAS. CONCLUSIONS: Resilience is negatively correlated with impulsivity and depression. Besides, it is also positively associated with cognitive function. Drug users with higher resilience may have a strong ability to mobilize psychological resources to create a good psychological environment, which may have a positive effect on the relief or improvement of symptoms.
Amphetamine-Related Disorders , Methamphetamine , Resilience, Psychological , Amphetamine-Related Disorders/complications , Amphetamine-Related Disorders/psychology , China , Cognition , Depression/psychology , Humans , Impulsive Behavior , Male , Methamphetamine/adverse effects
Objective: It is currently unclear whether the Helicobacter pylori (H. pylori) infection leads to associated alterations in thyroid functions and thyroidal illnesses. This study aims to analyse this relationship in an elderly male cohort over a five-year period. Design: A case retrospective study. Methods: A longitudinal study was designed to collect subjects (≥65 years old) receiving both a thyroid examination and H. pylori infection status determined by 13C-urea breath test in 2013 at our unit. Subjects were followed every 1 to 2 years until December 2017 for laboratory results, visits to outpatient clinics/emergency departments etc. Blood tests and thyroid ultrasonography were performed to determine thyroid function and morphology. Results: 356 male subjects with mean age 78.5 ± 9.8 years were included. Active H. pylori infection was positive in 88 subjects (24.7%). Thyroid function tests and ultrasonography showed similar patterns between H. pylori positive and negative groups. Non-thyroidal-illness syndrome (NTIS) was diagnosed in 30/210 (14%) patients who experienced acute illnesses and hospitalization over five-year follow-up. Notably, NTIS demonstrated significantly higher prevalence in the H. pylori positive group compared to the negative group (17.1 vs. 5.6%, P = 0.001). Multivariate analysis showed that when age, APACHE II score and hemoglobin levels were adjusted, H. pylori status still has significant interrelationship with NTIS (OR = 3.497, P = 0.003). Conclusions: There is a positive association between chronic active H. pylori infection and NTIS prevalence in this elderly male cohort. Further studies are needed to elucidate the role of H. pylori infection on NTIS in elderly male patients.
Aluminum honeycomb has been widely used in many industrial fields, especially the aeronautics and aerospace industries, owing to its high strength and stiffness to weight ratio. Machining of aluminum honeycomb is usually associated with deformations and burrs. Ultrasonic cutting has been introduced as a promising method to overcome these constraints. In order to conduct in-depth research on the ultrasonic cutting for aluminum honeycomb by disc cutter, a 3D finite element model is carried out and verification tests are performed. Comparison result of simulated and experimental cutting forces indicates that the developed model agrees well with the experiment. Based on the developed model, cutting forces and contact relationship between cutter and honeycomb during the cutting process are studied. The reason for the periodic increase in cutting force is analyzed, subsequently. Moreover, the stress distribution in the cutting zone and honeycomb morphologies under different cutting conditions are compared and analyzed. Results show that the hexagonal structure of aluminum honeycomb can be protected and machining quality can be improved by using ultrasonic vibration. Therefore, high quality and efficient machining for aluminum honeycomb can be achieved.
