ABSTRACT
To assess the resistance of the shipping network of Chinese iron ore imports and the effectiveness of different safeguards, an invulnerability simulation model was established to fill the gap that traditional evaluation methods fail to consider the overall flow and nodes load state of the network. The data of a state-owned enterprise, major export ports in the world and major import ports in China were used to build the initial network. The network with different numbers of import ports was attacked in particular ways. The simulation results show that the network has a certain self-healing ability after the network is attacked, because of the adjusted ability of ship routes and redistribution of cargo load, but the network invulnerability will suddenly change after the key nodes are affected. The improvement of overload capacity has obvious marginal changes in improving network invulnerability if the overload capacity reaches a critical point, and improving the network survivability may aggravate network congestion. Therefore, it is necessary to strengthen the protection of key nodes, increase the number of import ports, and enhance the overload capacity of the ports, to enhance the invulnerability of the Chinese iron ore import shipping network under the COVID-19 and other critical events. Meanwhile, resources such as wharf yards and equipment should be reasonably allocated to prevent and deal with network congestion. Copyright © 2022 by Science Press.
ABSTRACT
Up to now, the COVID-19 is still prevalent in many countries around the world, and threatens health security of global public seriously. China not only developed the reagent kits for detecting of SARS-CoV-2 nucleic acids and testing equipment, but also established 10 in 1 mixed detection strategy and related policies which have improved the efficiency of epidemic prevention and control, and ensured the health of the people. This review summarizes the principles, advantages, disadvantages and supporting equipment of various methods for the detection of SARS-CoV-2.
ABSTRACT
Corona virus disease 2019 (COVID-19) is a serious contagious disease that arises from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease is transmitted primarily through droplets transmission, which does not exclude the possibility of transmission through aerosols and digestive tract and other means. The majority of COVID-19 cases present as common and mild, while a few cases progress rapidly to the severe and critical stage, making it more difficult to save the disease. Current laboratory diagnostic approaches for COVID-19 are on the basis of pathogenic tests for viral nucleic acids, serological tests by specific antibody detection, and general tests. For now, Real-time quantitative PCR (qRT-PCR) is the gold standard for the detection of COVID-19, but the method is complicated and may have false-negative results. Therefore, in order to diagnose and prevention COVID-19 more effectively, it is needful to develop highly sensitive diagnostic methods with portable instruments and visualized results. This mini-review provides an overview of the current portable and visual assays of detection of COVID-19, in order to achieve early effective and more accurate diagnosis of COVID-19.
ABSTRACT
Many places on earth still suffer from a high level of atmospheric fine particulate matter (PM2.5) pollution. Formation of a particulate pollution event or haze episode (HE) involves many factors, including meteorology, emissions, and chemistry. Understanding the direct causes of and key drivers behind the HE is thus essential. Traditionally, this is done via chemical transport models. However, substantial uncertainties are introduced into the model estimation when there are significant changes in the emissions inventory due to interventions (e.g., the COVID-19 lockdown). Here we applied a Random Forest model coupled with a Shapley additive explanation algorithm, a post hoc explanation technique, to investigate the roles of major meteorological factors, primary emissions, and chemistry in five severe HEs that occurred before or during the COVID-19 lockdown in China. We discovered that, in addition to the high level of primary emissions, PM2.5 in these haze episodes was largely driven by meteorological effects (with average contributions of 30-65 mu g m(-3) for the five HEs), followed by chemistry (similar to 15-30 mu g m(-3)). Photochemistry was likely the major pathway of formation of nitrate, while air humidity was the predominant factor in forming sulfate. Our results highlight that the machine learning driven by data has the potential to be a complementary tool in predicting and interpreting air pollution.
ABSTRACT
Objective: To explore the mechanism of Kangguan decoction in the treatment of coronavirus disease 2019 (COVID-19) and then perform preliminary verification. Methods: The effective compounds and target genes of Kangguan decoction were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. COVID-19 related target genes were searched in the GeneCards database. The active target genes of Kangguan decoction acting on COVID-19 were identified to perform GO function enrichment and KEGG pathway enrichment analysis. The compound-target network and protein-protein interaction were constructed;Molecular docking simulations of macromolecular protein target receptors and their corresponding compounds were performed. The clinical data of COVID-19 patients were retrieved from their electronic medical records of Nantong Third People's Hospital. Results: We screened out 137 effective compounds and 274 effective target genes of Kangguan decoction from TCMSP. The active target genes of Kangguan decoction were compared with the COVID-19 related target genes, and 63 active target genes for Kangguan decoction acting on COVID-19 were identified. GO function enrichment and KEGG pathway enrichment analysis were performed. The compound-target network and PPI network were constructed and the key compounds and key targets were selected to construct a key compound-target network. Finally, the binding of the target and its corresponding components was verified by molecular docking and two clinical cases with obvious clinical efficacy after Kangguan decoction application were demonstrated. Conclusion: The pharmacological mechanism of Kangguan decoction acting on COVID-19 has been explored, and the active compounds and targets of Kangguan decoction acting on COVID-19 and clinical efficacy for Kangguan decoction treating COVID-19 patients have been preliminarily verified.
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This paper analyzes the history of currency development from physical currency, metal currency, paper currency to electronic currency, analyzes the evolution of the international currency settlement system, its pros and cons, and the global financial changes caused by the epidemic;analyzes the problem as to how the U.S. dollar is bound to gold and oil, i.e., the process of international hegemonic currency, and analyzes the overall impact of the outbreak of the epidemic in 2020 on the economy, the over-issue of the U.S. dollar, the continued weakening of the U.S. dollar index, and the strengthening of the hedging effect of gold and silver. Under this change, global precious metal mergers and acquisitions have increased, countries have increased their gold reserves and made exploratory promotion of a new currency system tied to gold. From the perspective of safeguarding national financial security and the internationalization of RMB, this paper puts forward suggestions for increasing the reserves of gold and silver at home and abroad, raising government reserves and private reserves in the medium and long term, and speeding up the launch of RMB internationalized gold and silver anchors. © 2021, Science Press. All right reserved.
ABSTRACT
At present, the COVID-19 epidemic is still spreading around the world, which greatly affects the global supply of mineral resources. Due to numerous resources supply nodes and complex and changeable risk factors, it is urgent to carry out comprehensive research on the supply base, supply node and supply chain of mineral resources from the perspective of production and transportation supply chain. Based on the global perspective and long-term research on risk assessment and countermeasures of global mineral resources, this paper puts forward the concept, connotation and evaluation method of mineral resources supply chain for the first time and traces the whole chain of mineral products from production, transportation and smelting process in space. With the mineral resources supply base as the entry point, the method of determination and comprehensive evaluation of mineral resources supply base based on space technology is established to realize the transformation of the delineation of mineral resources supply base from the traditional planarization to the spatialization. The collation and stipulation of the technical system through the establishment of supply key nodes and supply chain of mineral resources can collate and stipulate supply chain and key knots by systematically taking into consideration the mineral resources supply of the target country, and can utilize the risk evaluation method of the mineral resources supply chain to carry out risk evaluation directed against the supply chain. These measures help the target country wholly grasp hidden risk of the mineral resources supply chain and, according to different forewarning grades, draw up safety contingency plans in accord with different grades and kinds, thus guaranteeing continued and stable supply of mineral resources. © 2021, Science Press. All right reserved.
ABSTRACT
Iron is the most widely used metal in China. There have been many changes in the international iron ore market due to the covid-19. Analyzing the reasons for the changes in the international iron ore supply, demand and market structure and predicting the future trends are of great significance for the stable supply of iron ore. This paper first analyzes the global steel production, iron ore supply and price trends under the covid-19 and believes that the global iron ore supply and demand pattern is further concentrated, showing a pattern of "two countries, two 60%". That is to say, China's steel production will further improve its global share, approaching 60%;Australia's supply share in the global iron ore shipping market will further increase, approaching 60%, because of the covid-19. Secondly, this paper predicts the changing trend of China's and global steel demand in the next 2-3 years, and believes that the main reason for the increase in China's steel production in recent years is the country's need for stable economic growth. China's steel production will remain high in the next 2~3 years, but in the long run, China's iron ore demand will slow down after a period of time. Finally, this paper analyzes the global iron ore price trend and believes that the global iron ore price will rise and fall to less than 100 US dollars/ton in the fourth quarter of 2020. The iron ore price will slowly fluctuate and fall down to 60~80 US dollars/ton in the next 2~3 years. © 2021, Science Press. All right reserved.