Fundamental Research最新文献

The environmental stability of infectious viruses in the laboratory setting is crucial to the transmission potential of human respiratory viruses. Different experimental techniques or conditions used in studies over the past decades have led to diverse understandings and predictions for the stability of viral infectivity in the atmospheric environment. In this paper, we review the current knowledge on the effect of simulated atmospheric conditions on the infectivity of respiratory viruses, mainly focusing on influenza viruses and coronaviruses, including severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome coronavirus. First, we summarize the impact of the experimental conditions on viral stability; these involve the methods of viral aerosol generation, storage during aging and collection, the virus types and strains, the suspension matrixes, the initial inoculum volumes and concentrations, and the drying process. Second, we summarize and discuss the detection methods of viral infectivity and their disadvantages. Finally, we integrate the results from the reviewed studies to obtain an overall understanding of the effects of atmospheric environmental conditions on the decay of infectious viruses, especially aerosolized viruses. Overall, this review highlights the knowledge gaps in predicting the ability of viruses to maintain infectivity during airborne transmission.

Current assessment of air quality or control effectiveness is solely based on particulate matter (PM) mass levels, without considering their toxicity differences in terms of health benefits. Here, we collected a total of 465 automobile air conditioning filters from 31 major Chinese cities to study the composition and toxicity of PM at a national scale. Dithiothreitol assay showed that normalized PM toxicity (NIOG) in different Chinese cities varied greatly from the highest 4.99 × 10⁻³ for Changsha to the lowest 7.72 × 10⁻⁴ for Yinchuan. NIOG values were observed to have significant correlations with annual PM₁₀ concentration (r = -0.416, p = 0.020) and some PM components (total fungi, SO₄²⁻ and calcium element). The concentrations of different elements and water-soluble ions in PM also varied by several orders of magnitude for 31 cities in China. Endotoxin concentrations in PM analyzed using limulus amebocyte lysate assay ranged from 2.88 EU/mg PM (Hangzhou) to 62.82 EU/mg PM (Shijiazhuang) among 31 Chinese cities. Besides, real-time qPCR revealed 10∼100-fold differences in total bacterial and fungal levels among 31 Chinese cities. The concentrations of chemical (water soluble ions and trace elements) and biological (fungi, bacteria and endotoxin) components in PM were found to be significantly correlated with some meteorological factors and gaseous pollutants such as SO₂. Our results have demonstrated that PM toxicity from 31 major cities varied greatly up to 6.5 times difference; and components such as fungi and SO₄²⁻ in PM could play important roles in the observed PM toxicity. The city-specific air pollution control strategy that integrates toxicity factors should be enacted in order to maximize health and economic co-benefits. This work also provides a comprehensive view on the overall PM pollution situation in China.

Land public transport is an important link within and between cities, and how to control the transmission of COVID-19 in land public transport is a critical issue in our daily lives. However, there are still many inconsistent opinions and views about the spread of SARS-CoV-2 in land public transport, which limits our ability to implement effective interventions. The purpose of this review is to overview the literature on transmission characteristics and routes of the epidemic in land public transport, as well as to investigate factors affecting its spread and provide feasible measures to mitigate the infection risk of passengers. We obtained 898 papers by searching the Web of Science, Pubmed, and WHO global COVID database by keywords, and finally selected 45 papers that can address the purpose of this review. Land public transport is a high outbreak area for COVID-19 due to characteristics like crowding, inadequate ventilation, long exposure time, and environmental closure. Different from surface touch transmission and drop spray transmission, aerosol inhalation transmission can occur not only in short distances but also in long distances. Insufficient ventilation is the most important factor influencing long-distance aerosol transmission. Other transmission factors (e.g., interpersonal distance, relative orientation, and ambient conditions) should be noticed as well, which have been summarized in this paper. To address various influencing factors, it is essential to suggest practical and efficient preventive measures. Among these, increased ventilation, particularly the fresh air (i.e., natural ventilation), has proven to effectively reduce indoor infection risk. Many preventive measures are also effective, such as enlarging social distance, avoiding face-to-face orientation, setting up physical partitions, disinfection, avoiding talking, and so on. As research on the epidemic has intensified, people have broken down many perceived barriers, but more comprehensive studies on monitoring systems and prevention measures in land public transport are still needed.

The appearance and wide use of memory hardware bring significant changes to the conventional vertical memory hierarchy that fails to handle contentions for shared hardware resources and expensive data movements. To deal with these problems, existing schemes have to rely on inefficient scheduling strategies that also cause extra temporal, spatial and bandwidth overheads. Based on the insights that the shared hardware resources trend to be uniformly and hierarchically offered to the requests for co-located applications in memory systems, we present an efficient abstraction of memory hierarchies, called Label, which is used to establish the connection between the application layer and underlying hardware layer. Based on labels, our paper proposes LaMem, a labeled, resource-isolated and cross-tiered memory system by leveraging the way-based partitioning technique for shared resources to guarantee QoS demands of applications, while supporting fast and low-overhead cache repartitioning technique. Besides, we customize LaMem for the learned index that fundamentally replaces storage structures with computation models as a case study to verify the applicability of LaMem. Experimental results demonstrate the efficiency and efficacy of LaMem.

A gradual increase in avian influenza outbreaks has been found in recent years. It is highly possible to trigger the next human pandemic due to the characteristics of antigenic drift and antigenic shift in avian influenza virus (AIV). Although great improvements in understanding influenza viruses and the associated diseases have been unraveled, our knowledge of how these viruses impact the gut microbiome of both poultry and humans, as well as the underlying mechanisms, is still improving. The “One Health” approach shows better vitality in monitoring and mitigating the risk of avian influenza, which requires a multi-sectoral effort and highlights the interconnection of human health with environmental sustainability and animal health. Therefore, monitoring the gut microbiome may serve as a sentinel for protecting the common health of the environment, animals, and humans. This review summarizes the interactions between AIV infection and the gut microbiome of poultry and humans and their potential mechanisms. With the presented suggestions, we hope to address the current major challenges in the surveillance and prevention of microbiome-related avian influenza with the “One Health” approach.

The discovery of covalent H₃S and clathrate structure LaH₁₀ with excellent superconducting critical temperatures at high pressures has facilitated a multitude of research on compressed hydrides. However, their superconducting pressures are too high (generally above 150 GPa), thereby hindering their application. In addition, making room-temperature superconductivity close to ambient pressure in hydrogen-based superconductors is challenging. In this work, we calculated the chemically “pre-compressed” Be-H by heavy metals Th and Ce to stabilize the superconducting phase near ambient pressure. An unprecedented ThBeH₈ (CeBeH₈) with a “fluorite-type” structure was predicted to be thermodynamically stable above 69 GPa (76 GPa), yielding a T_c of 113 K (28 K) decompressed to 7 GPa (13 GPa) by solving the anisotropic Migdal–Eliashberg equations. Be-H vibrations play a vital role in electron–phonon coupling and structural stability of these ternary hydrides. Our results will guide further experiments toward synthesizing ternary hydride superconductors at mild pressures.

Public clouds favor sharing of storage resources, in which many tenants acquire bandwidth and storage capacity from a shared storage pool. To provide high availability, data are often encoded to provide fault tolerance with low storage costs. Regarding this, efficiently organizing an encoded storage system for shared I/Os is critical for application performance. This is usually hard to achieve as different applications have different stripe configurations and fault tolerance levels. In this paper, we first study the block trace from the Alibaba cloud, and find that I/O patterns of modern applications prefer the resource sharing scheme. Based on this, we propose a globally shared resource paradigm for encoded storage system in the public cloud. The globally shared resource paradigm can provide balanced load and fault tolerance for numerous disk pool sizes and arbitrary application stripe configurations. Furthermore, we demonstrate with two case studies that our theory can help address the device-specific problems of HDD and SSD RAID arrays with slight modifications: comparing the existing resource partition and resource sharing methods, our theory can promote the rebuild speed of the HDD RAID arrays by 2.5$\times$, and reduce the P99 tail latency of the SSD arrays by up to two orders of magnitude.