Abstract
Background
The COVID-19 pandemic has wreaked havoc on the aviation and education sectors in China. This study examined the relationships between risk perceptions of the pandemic, vocational ...identity, and employment aspirations of Chinese aviation students.
Methods
The study used a convenience sampling approach to collect data (n = 276 respondents) from August 2 to 8, 2022. An online survey was sent via WeChat and QQ to Chinese students majoring in aviation service management who were under lockdown at six Chinese schools.
Results
In spite of the strong support for the stringent COVID policies and full awareness of infection risk and protective measures, respondents were worried about the current unstable situation and felt fear for its severity and long-lasting symptoms. The casual path from career commitment to employment aspiration was supported, but high risk perceptions of the pandemic failed to have any psychological effect on the two constructs of vocational identity and employment aspirations.
Conclusions
The findings not only demonstrate the power of career commitment on employment aspirations but also reveal that a relatively high self-assessment of career proficiency may not necessarily lead to a clear career aspiration, possibly due to poor risk communication and insufficient career planning guidance. Thus, Chinese aviation students should improve their career proficiency and commitment, broaden their career options and adaptability, and have a clear career plan, in order to be well prepared for the fierce job market that will face the next wave of the ongoing pandemic.
Individual crystals of zircon, from the Koktokay No. 3 granitic pegmatite vein, are variably altered and consist of three types of domains distinguished on the basis of textures and compositions. The ...pristine domains possess normal chondrite-normalized rare earth element (REE) patterns. Domains affected by metamictization are enriched in U and Th. The presence of abundant fractures, dense pores, and the enrichments of non-formula elements imply that these metamict domains have been altered by a later hydrothermal fluid. Tetrads observed in these altered domains are likely to have been generated by this alteration event.
Porous metals are very popular functional materials that have been used for various fields due to their attractive properties such as high porosity, controllable permeability, and high specific ...surface area, etc. This study provides an overall review of the fabrication, characterization and application of the porous metal materials (PMMs) for polymer electrolyte membrane fuel cell (PEMFC) applications. Metal foams, porous metal sinters, metal meshes and perforated metals are included. Such materials have been used as flow distributor/flow field, current collector, gas diffusion backing and also catalyst support. Different applications require different dominant characteristics of the PMMs. Although the feasibility of using the PMMs for PEMFC applications have been comprehensively validated by both modeling and experimental investigations, there still exists plenty of scope to explore the in-depth mechanisms concerning how and how much the PMMs contribute to the fuel cell performance. This work not only summarizes the development of this subject, but also analyzes the challenges that must be overcome in the future. Moreover, a systematical optimization link for active functional design (AFD) of PEMFC-oriented PMMs is also presented.
We propose that there may be a substantial stochastic gravitational wave (GW) background from particle origin, mainly from the gravitational three-body decay of the inflaton. The emitted gravitons ...could constitute a sizable contribution to dark radiation if the mass of inflaton is close to the Planck scale, which may be probed by future CMB experiments that have a sensitivity on the deviation of the effective number of neutrinos in the standard cosmology, δNeff∼0.02−0.03. We have also illustrated the spectrum of the radiated gravitational waves, in comparison to the current and future experiments, and found that GWs from particle origin could be the dominant contribution to the energy density at high-frequency domain, but beyond the sensitivity regions of various GW experiments in the near future.
We identified a novel circovirus (human-associated circovirus 2 HuCV2) from the blood of 2 intravenous drug users in China who were infected with HIV-1, hepatitis C virus, or both. HuCV2 is most ...closely related to porcine circovirus 3. Our findings underscore the risk for HuCV2 and other emerging viruses among this population.
DNA topoisomerase II (topo II) is an important enzyme involved in DNA replication, recombination, and repair. Despite the popular applications of topo II inhibitors in cancer therapy, there is still ...an urgent need to upgrade topo II inhibitors to cope with drug resistance and severe adverse effects. Accordingly, novel topo II catalytic or multitarget topo II inhibitors are gaining more attention and make it possible to ease the toxic limitations of topo II poisons. In this review, medicinal chemistry approaches are mainly discussed toward the development of potent topo II inhibitors with low toxicities.
Extracellular purines are signaling molecules in the neurogenic niches of the brain and spinal cord, where they activate cell surface purinoceptors at embryonic neural stem cells (NSCs) and adult ...neural progenitor cells (NPCs). Although mRNA and protein are expressed at NSCs/NPCs for almost all subtypes of the nucleotide‐sensitive P2X/P2Y, and the nucleoside‐sensitive adenosine receptors, only a few of those have acquired functional significance. ATP is sequentially degraded by ecto‐nucleotidases to ADP, AMP, and adenosine with agonistic properties for distinct receptor‐classes. Nucleotides/nucleosides facilitate or inhibit NSC/NPC proliferation, migration and differentiation. The most ubiquitous effect of all agonists (especially of ATP and ADP) appears to be the facilitation of cell proliferation, usually through P2Y1Rs and sometimes through P2X7Rs. However, usually P2X7R activation causes necrosis/apoptosis of NPCs. Differentiation can be initiated by P2Y2R‐activation or P2X7R‐blockade. A key element in the transduction mechanism of either receptor is the increase of the intracellular free Ca2+ concentration, which may arise due to its release from intracellular storage sites (G protein‐coupling; P2Y) or due to its passage through the receptor‐channel itself from the extracellular space (ATP‐gated ion channel; P2X). Further research is needed to clarify how purinergic signaling controls NSC/NPC fate and how the balance between the quiescent and activated states is established with fine and dynamic regulation. GLIA 2017;65:213–230
Main Points
Embryonic neural stem cells (NSCs) and adult neural progenitor cells (NPCs) are both endowed with receptors responding to extracellular nucleotides.
Extracellular nucleotides act at various subtypes of P2 receptors located at NSCs/NPCs.
Nucleotides regulate NSC/NPC proliferation (or necrosis/apoptosis), as well as migration and differentiation.
TGF-β is known to influence tumour progression. Here we report an additional role of Smad3 in the tumour microenvironment regulating cancer progression. Deletion or inhibition of Smad3 in the tumour ...microenvironment suppresses tumour growth, invasion and metastasis in two syngeneic mouse tumour models. Smad3
bone marrow gives rise to an expanded NK cell population with enhanced tumour-suppressive activities in vivo, and promotes differentiation of NK cells ex vivo. We identify E4BP4/NFIL3 as a direct Smad3 target gene critical for NK cell differentiation. Smad3 suppresses transcription of IFN-γ via E4BP4 in a T-bet independent manner. Therefore disruption of Smad3 enhances both the E4BP4-mediated NK cell differentiation and anti-cancer effector functions in vivo and in vitro. Furthermore, systemic treatment with a Smad3 inhibitor SIS3 effectively suppresses cancer progression. In summary, suppression of NK cell-mediated immunosurveillance via the Smad3-E4BP4 axis contributes to cancer progression. We propose targeting Smad3-dependent tumour microenvironment may represent an effective anti-cancer strategy.
In this study, the impacts of heat curing conditions on the morphology and permeability of polyamide nanofiltration (NF) membranes were comprehensively investigated. The surface chemical composition, ...morphology, charge property, hydrophilicity and NF performance of the resulting membranes were studied. In order to preserve the instantaneous polyamide layer morphology, freeze drying process was employed after heat curing. Results showed that the surface roughness of the polyamide selective layer increased first and then decreased with curing time. The tunable morphology of polyamide NF membranes can be acquired by adjusting the curing temperature and time. The nascent membrane without heat curing exhibited excellent pure water permeability of 16.7 L m−2 h−1 bar−1 and maintained Na2SO4 rejection of 97.4%. Increasing the curing time, the permeability of the NF membranes was greatly diminished. This work provided novel viewpoint about the effects of heat curing on morphology and permeability for high-performance polyamide NF membrane.
•Interfacial polymerization is terminated by liquid nitrogen to preserve the instantaneous polyamide layer morphology.•Polyamide layer roughness increases first and then decreases as a function of the heat curing time.•The nascent membrane exhibited excellent pure water permeability of 16.7 L m−2 h−1 bar−1 and Na2SO4 rejection of 97.4%.
The small Kedengjian volcanic rock-hosted hydrothermal vein-type Cu deposit (100,000 t Cu metal content at about 3% Cu) is located in the Lanping Basin, one of several Mesozoic–Cenozoic continental ...sedimentary basins in the northern part of the Indochina block and in the eastern part of the North Qiangtang block. Many sediment-hosted base metal ore deposits with ages of < 65 Ma, which coincide with the Indian–Asian continental collision or the Himalayan orogeny, are present in these basins and are collectively referred to as the Sanjiang sediment-hosted base metal metallogenic belt. The Kedengjian volcanic rock-hosted hydrothermal vein-type Cu deposit has been commonly regarded as part of the Cenozoic Sanjiang sediment-hosted base metal metallogenic belt. We determined the age of mineralization for the Kedengjian deposit using hydrothermal titanite and molybdenite. The U–Pb ages of the first and second generations of titanite are 107.4 ± 5.6 Ma and 100.1 ± 3.4 Ma (2 σ), respectively. The associated molybdenite yields a Re–Os isochron age of 98.2 ± 2.2 Ma (2 σ) and a mean age of 98.3 ± 2.2 Ma, which are identical (within analytical error) to the U–Pb age of the younger titanite. Our new results indicate that the Kedengjian deposit formed at ~ 100 Ma, much older than the Cenozoic sediment-hosted base metal deposits in the Lanping Basin. This significant age difference dismisses the Kedengjian deposit as a member of the Cenozoic Sanjiang sediment-hosted base metal metallogenic belt. The Kedengjian deposit formed during the Late Cretaceous subduction of the Neo-Tethys oceanic plate beneath the previously amalgamated Indochina and North Qiangtang blocks of the Asian continent. On the basis of this tectonic correlation, we suggest that there is potential for pre-Cenozoic hydrothermal Cu mineralization in the region.
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