Proposal to apply a "Positive Emotion, Engagement, Relationships, Meaning, and Accomplishment (PERMA)" based approach to manage the COVID-19-related mental health problems in the era of long COVID.

Long COVID (LC)-related health problems are highly concerned. Many patients seem to have "recovered" from an acute SARS-CoV-2 infection, however, they might experience various symptoms, almost involving all organs and systems. Of those, neuropsychiatric symptoms like depression, anxiety, and post-traumatic stress disorder (PTSD) are not rare. These problems significantly impact the quality of life (QOL) of patients, family, and caregivers, even lead a tragic suicide outcome. Other than the conventional psychological and medical approaches, here, we proposal a positive emotion, engagement, relationships, meaning, and accomplishment (PERMA)-based approach to fight against these COVID-19-related mental health problems (CRMHPs). This approach is characterized by positive psychological interventions and self-achievements, which has been proved to be a powerful tool against mood disorders in common people. Nowadays, abolishment of certain prophylactic measures (such as isolation, lockdown, compulsorily wearing a mask and maintaining social distance, measures to avoid crowding) enables us to have more opportunities to contact patients and implement the PERMA-based approach to the patients with CRMHPs. We believe that application of PERMA-based approach is conducive to alleviate the influence of the CRMHPs and improve their QOL.

Numerical Simulation on Solidification during Vertical Centrifugal Casting Process for TC4 Alloy Wheel Hub with Enhanced Mechanical Properties.

The Ti-6Al-4V (TC4) alloy wheel hub has exhibited some defects that affect the properties during the vertical centrifugal casting process. Therefore, the analysis of the solidification process would contribute to solving the above-mentioned problems. In this study, an orthogonal experimental design was employed to optimize the process parameters (rotational speed, mold preheating temperature, and pouring temperature) of the vertical centrifugal casting method. The effects of process parameters on the velocity field, temperature field, and total shrinkage porosity during the solidification process were explored, and the microstructure and mechanical properties of the wheel hub prepared by the vertical centrifugal casting method were also investigated. The results showed that the rotational speed mainly induced the change of the velocity field. The pouring temperature and mold preheating temperature affected the temperature field and solidification time. Based on the analysis of the orthogonal experiment, the optimal parameters were confirmed as a rotational speed of 225 rpm, mold preheating temperature of 400 °C, and pouring temperature of 1750 °C, respectively. The simulation results of total shrinkage porosity were in agreement with the experiment results. The wheel hub was composed of nonuniform α and ß phases. The lath α phase precipitated from larger ß grains with different orientations. Compared with the other samples at different locations, the α phase in the PM sample (middle of the TC4 wheel hub) displayed high peak intensity and uniformly distributed ß phase along the radial direction of the wheel hub. Moreover, the PM sample revealed a higher tensile strength of 820 MPa and similar Vickers hardness of 318 HV compared with the other samples at different locations, which were higher than those of rolling and extrusion molding. This experiment design would provide a good reference for the vertical centrifugal casting of the TC4 alloy.

Effect of Aging Treatment on Microstructural Evolution and Mechanical Properties of the Electron Beam Cold Hearth Melting Ti-6Al-4V Alloy.

Ti-6Al-4V (Ti64 or TC4) alloy is widely used in the industrial field. However, there have been few studies of the TC4 alloy melted by electron beam cold hearth melting (EBCHM) technology. Aging treatment has a considerable influence on the secondary α-phase in titanium alloys. Therefore, TC4 alloy melted by EBCHM technology was investigated in this study. The effect of different aging times on the microstructural evolution and mechanical properties of titanium alloy sheets was evaluated. The results showed that, with increase in aging time, the primary α-phase enlarged and grain globularization occurred. In addition, some transformed ß-phases disappeared. The strength and Vickers hardness of the heat-treated sheets decreased, while the plasticity increased with increase in aging time, indicating that the mechanical properties developed with evolution of the microstructure. After aging at 560 °C for 2 h, the properties overall were optimal. The type of fracture of the samples was ductile fracture; the dimples became larger with increase in aging time. After heat treatment, the recrystallized nucleus, substructures and HAGBs increased, while the deformed structure and LAGBs decreased. Some grains had rotated following heat treatment, indicating that anisotropy was greatly reduced.

The 4Rs approach to COVID-19 emergency management during the post-pandemic period: What lessons can be learned from Shenzhen, China?

The Omicron variant of SARS-CoV-2 (or Omicron) is extremely contagious and has swept the world in a short period. Shenzhen-a new international city in China with a permanent population of 17.56 million and covering nearly 2000 square kilometers-was attacked by Omicron in 2022. However, the pandemic was controlled in a very short time as a result of prompt government reaction that prevented the variant's further spread. The total number of cases in this wave of the pandemic was more than 2600. Shenzhen's successful experience in tackling the Omicron wave deserves in-depth discussion. Proposed by American scholar Robert Heath, the 4Rs model aims to reduce the harm from a crisis through the measures of reduction, readiness, response, and recovery. This article presents the successful experience of Shenzhen's local government and the Third People's Hospital of Shenzhen, the only hospital in Shenzhen designated to use the 4Rs emergency management model for the treatment of COVID-19 during the 2022 Omicron wave of the pandemic.

Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt.

In this work, an electric current pulse (ECP) of 500A was applied on a hypereutectic high chromium cast iron (HHCCI) melt before it began to solidify, and the effect of ECP on primary carbides was investigated. The characteristics of the primary carbides were analyzed by X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), transmission electron microscopy (TEM), micro hardness tester, and other techniques. The results showed that ECP not only refined the primary (Cr, Fe)7C3 carbides, but also decreased the average content of Cr in the primary carbides. At the same time, the average value of micro hardness of the primary carbides increased by about 84 Kgf/mm², which contradicts existing knowledge that hardness increases with an increase in Cr content. XRD analysis showed that the crystal structure of the primary carbides did not change. The results of EPMA indicated that the Cr/Fe ratio gradually decreased from the center to the edges of the carbide particles. Further investigation revealed that the uneven distribution of elements caused by ECP led to an increase in defects (including twins, antiphase boundaries, and dislocations). This increase in defect density is the main reason for the increase in micro hardness instead of the expected decrease. The mechanism of the change in primary carbides was analyzed in detail in this paper, which has provided a new method for the refinement of primary carbides and for improving the properties of primary carbides.

Effect of Electric Current Pulse on Microstructure and Corrosion Resistance of Hypereutectic High Chromium Cast Iron.

The effect of electric current pulse on the microstructure and corrosion resistance of hypereutectic high chromium cast iron was explored. The morphology of carbides in solidification microstructure was observed by an optical microscope and a scanning electron microscope and the composition was determined by an electron probe micro-analyzer. The microhardness of primary carbides and corrosion resistance of samples were also compared. Under the active of electric current pulse, the microstructure of hypereutectic high chromium cast iron was homogenized and its performance improved accordingly. On treatment by electric current, the morphology of primary carbides changed from thick long rods to hexagonal blocks or granular structures. The interlayer spacing of eutectic carbide decreased from ~26.3 µm to ~17.8 µm. Size statistics showed that the average diameter of primary carbide decreased from ~220 µm to ~60 µm. As a result, microhardness increased from 1412 HV to 1511 HV. No obvious microcrack propagation was found at the microindentation sites. The average length of microcracks decreased from ~20.7 µm to ~5.7 µm. Furthermore, corrosion resistance was remarkably enhanced. The average corrosion rate decreased from 2.65 mg/cm²·h to 1.74 mg/cm²·h after pulse current treatment.

Electronic structure and optical properties of resin.

We used the density of functional theory (DFT) to study the electronic structure and density of states of resin by ab initio calculation. The results show the band gap of resin is 1.7 eV. The covalent bond is combined C/O atoms with H atoms. The O 2p orbital is the biggest effect near the Fermi level. The results of optical properties show the reflectivity is low, and the refractive index is 1.7 in visible light range. The highest absorption coefficient peak is in 490 nm and the value is 75,000.

[Electrochemical reduction characteristics and mechanism of chlorinated hydrocarbon at the copper electrode].

The electrochemical reduction characteristics of chlorinated hydrocarbons were investigated by applying cyclic voltammetry technique. The reduction mechanism and reactivity of the chlorinated hydrocarbons at the copper electrodes were explored. The relation between the reductive reactivity at the copper electrode and the structures of this kind of compounds was discussed. The experimental results show that chlorinated paraffin hydrocarbons and a portion of chlorinated aromatic hydrocarbons could be reduced directly at the copper electrode; however, chlorinated aromatic hydrocarbons aren't easy to reduced directly at the copper electrode. The results provide a theoretical basis for the catalyzed iron inner electrolysis method.