Minute-Cadence Observations of the LAMOST Fields with the TMTS V. Machine Learning Classification of TMTS Catalogues of Periodic Variable Stars

Periodic variables are always of great scientific interest in astrophysics. Thanks to the rapid advancement of modern large-scale time-domain surveys, the number of reported variable stars has experienced substantial growth for several decades, which significantly deepened our comprehension of stellar structure and binary evolution. The Tsinghua University-Ma Huateng Telescopes for Survey (TMTS) has started to monitor the LAMOST sky areas since 2020, with a cadence of 1 minute. During the period from 2020 to 2022, this survey has resulted in densely sampled light curves for ~ 30,000 variables of the maximum powers in the Lomb-Scargle periodogram above the 5sigma threshold. In this paper, we classified 11,638 variable stars into 6 main types using XGBoost and Random Forest classifiers with accuracies of 98.83% and 98.73%, respectively. Among them, 5301 (45.55%) variables are newly discovered, primarily consisting of Delta Scuti stars, demonstrating the capability of TMTS in searching for short-period variables. We cross-matched the catalogue with Gaia's second Data Release (DR2) and LAMOST's seventh Data Release (DR7) to obtain important physical parameters of the variables. We identified 5504 Delta Scuti stars (including 4876 typical Delta Scuti stars and 628 high-amplitude Delta Scuti stars), 5899 eclipsing binaries (including EA-, EB- and EW-type) and 226 candidates of RS Canum Venaticorum. Leveraging the metal abundance data provided by LAMOST and the Galactic latitude, we discovered 8 candidates of SX Phe stars within the class of "Delta Scuti stars". Moreover, with the help of Gaia color-magnitude diagram, we identified 9 ZZ ceti stars.Comment: 20 pages, 14 figures, accepted to MNRA

Autocatalytic reduction-assisted synthesis of segmented porous PtTe nanochains for enhancing methanol oxidation reaction

Morphology engineering has been developed as one of the most widely used strategies for improving the performance of electrocatalysts. However, the harsh reaction conditions and cumbersome reaction steps during the nanomaterials synthesis still limit their industrial applications. Herein, one-dimensional (1D) novel-segmented PtTe porous nanochains (PNCs) were successfully synthesized by the template methods assisted by Pt autocatalytic reduction. The PtTe PNCs consist of consecutive mesoporous architectures that provide a large electrochemical surface area (ECSA) and abundant active sites to enhance methanol oxidation reaction (MOR). Furthermore, 1D nanostructure as a robust sustaining frame can maintain a high mass/charge transfer rate in a long-term durability test. After 2,000 cyclic voltammetry (CV) cycles, the ECSA value of PtTe PNCs remained as high as 44.47 m2·gPt–1, which was much larger than that of commercial Pt/C (3.95 m2·gPt–1). The high catalytic activity and durability of PtTe PNCs are also supported by CO stripping test and density functional theory calculation. This autocatalytic reduction-assisted synthesis provides new insights for designing efficient low-dimensional nanocatalysts

Comprehensive Management and Coordination Mechanism of Marine Economy

With the rapid development of economy and society and the continuous progress of science and technology, the public demand for marine products and services is increasing, and the marine economic and social benefits are rising. It is very important to improve the management level of marine economy. The purpose of this study is to analyze the comprehensive management and coordination mechanism of China’s marine economy. This study selects Lianyungang City as the research object and takes the marine economic data from 2010 to 2019 as the research data. This study establishes three evaluation index systems of marine economic development. Then, according to the influence of the marine industry development, social development, population, marine resources and environment, regional scientific and technological innovation ability, government comprehensive management, and other factors on the regional marine economic management, this paper puts forward a set of marine economy comprehensive coordination management system and method and evaluates the current situation of marine economic development in Lianyungang City. The results show that, in the 10 years from 2010 to 2019, the comprehensive management evaluation value of China’s marine economy has increased from 0.20 to 0.33, with an average annual increase of 6.57 percentage points. The system level has been upgraded from the initial “poor” to “average,” achieving rapid growth. It is concluded that the index system evaluation of this study well reflects the change of the management level of China’s marine economy and has a promoting effect on the development of China’s marine economy, making contributions to China’s economic management

α-Linolenic acid alleviates aluminum toxicity in RAW264.7 cells by antioxidative and anti-inflammatory effects

Aluminum is an inorganic contaminant and has adverse effects on human and animal health by mainly accumulating in the immune system to exert toxicity. α-Linolenic acid (ALA), a crucial dietary component, possesses various bioactivities. Nevertheless, the effects of ALA on Al-induced toxicity have not been sufficiently understood. In this study, we aimed to elucidate the possible mechanism of aluminium chloride hexahydrate (AlCl3·6H2O, Al) exposure to RAW264.7 cells and the response of ALA through an RNA sequencing (RNA‐seq). RNA-seq results demonstrated that Al exposure resulted in 2106 differentially expressed genes (DEGs) with 53 pathways, including the NF-κB, enriched by the KEGG analysis. 200 of the 2106 DEGs were modulated in ALA-pretreated group, which were enriched into 36 pathways, containing the NF-κB. qRT-PCR results displayed the RNA-seq's reproducibility and reliability. Western blot analysis confirmed that the protection of ALA against Al toxicity was associated with NF-κB mediated JAK2/STAT3/SOCS3 pathway and HO-1 activation. These results elucidated the protection of ALA against Al-induced toxicity from a new perspective and provided a potential therapy for Al treatment

Transmission and infection risk of various pathogen-laden expiratory droplets in a coach bus with COVID-19

The study about droplet transmission in crowded, poorly ventilated buses and the resulting infection risk(IR) remains rare. Based on a COVID-19 outbreak which the index patient located at bus rear, we performed CFD simulations to study the effect of initial droplet diameters and hourly ventilation rate(ACH) on droplet transmission and IR. The outdoor pressure differential creates the natural ventilation enters from theskylight at bus rear and exits from the front one. With increased ACH, the IR of tracer gas reduced quickly, from 11.1-15.3% under 0.62ACH to 1.3-3.1% under 5.66ACH. Furthermore, the IR of 100μm/50μm droplets was almost independent of ACH as most droplets were deposited due to gravity. Furthermore, 5μm droplets are more widely dispersed than larger droplets, and can spread further with increasing ACH with a low IR(≤0.4%). Unlike general rooms, most droplets are deposited on the route passing through the long-distance bus space(~9.46m). But the tracer gas will not deposit, so the tracer gas can only be used to simulate the fine droplet dispersion process in the long-distance bus. Our research results provide a reference for future research on droplet transmission in the bus environment, and also provide a guidance for epidemic prevention

8,9-Dihydrocannabidiol, an Alternative of Cannabidiol, Its Preparation, Antibacterial and Antioxidant Ability

Cannabidiol (CBD) from Cannabis sativa is used in cosmetics in North America due to its antibacterial and antioxidant properties, but has been prohibited in many countries except recently; so, finding a non-intoxicating CBD alternative and elucidating the structure–function relationship of CBD analogues is becoming increasingly relevant. Herein, a set of CBD analogues including 8,9-dihydrocannabidiol (H2CBD) was synthesized, and their antibacterial, bactericidal, and antioxidant activity, as well as their structure–function relationship, were studied. The results present a catalytic selectivity near 100% towards H2CBD with a production yield of 85%. Each CBD analogue presented different antibacterial and antioxidant activity. It is revealed that the phenolic hydroxyl moiety is an essential group for CBD analogues to perform antibacterial and antioxidant activities. Among them, H2CBD presented much stronger antibacterial activity than the assayed popular antibiotics. H2CBD and Compound 4 presented very similar radical scavenging activity and inhibition on lipid oxidation to vitamin C, but better thermostability. Moreover, H2CBD presented lower toxicity to human skin fibroblasts at concentrations up to 64-fold higher than its MIC value (1.25 μg/mL) against S. aureus. Above all, in all property experiments, H2CBD presented extremely similar performance to CBD (p < 0.05), including similar time–kill kinetics curves. This research finds H2CBD to be an alternative for CBD with very high potential in the aspects of antibacterial, bactericidal, and antioxidant activity, as well as lower toxicity to human skin fibroblasts

Novel identity-based hash proof system with compact master public key from lattices in the standard model

2019 World Scientific Publishing Company. As the progress of quantum computers, it is desired to propose many more efficient cryptographic constructions with post-quantum security. In the literatures, almost all cryptographic schemes and protocols can be explained and constructed modularly from certain cryptographic primitives, among which an Identity-Based Hash Proof System (IB-HPS) is one of the most basic and important primitives. Therefore, we can utilize IB-HPSs with post-quantum security to present several types of post-quantum secure schemes and protocols. Up until now, all known IB-HPSs with post-quantum security are instantiated based on latticed-based assumptions. However, all these lattice-based IB-HPSs are either in the random oracle model or not efficient enough in the standard model. Hence, it should be of great significance to construct more efficient IB-HPSs from lattices in the standard model. In this paper, we propose a new smooth IB-HPS with anonymity based on the Learning with Errors (LWE) assumption in the standard model. This new construction is mainly inspired by a classical identity-based encryption scheme based on LWE due to Agreawal et al. in Eurocrypt 2010. And our innovation is to employ the algorithm SampleGaussian introduced by Gentry et al. and the property of random lattice to simulate the identity secret key with respect to the challenge identity. Compared with other existing IB-HPSs in the standard model, our master public key is quite compact. As a result, our construction has much lower overheads on computation and storage

A Novel Dual-Branch Neural Network Model for Flood Monitoring in South Asia Based on CYGNSS Data

Microwave remote sensing is widely applied in flood monitoring due to its independence from severe weather conditions, which usually restrict the usage of optical sensors. However, it is challenging to track the variation process of flood events in a timely manner by traditional active and passive microwave techniques, since they cannot simultaneously provide measurements with high spatial and temporal resolution. The emerging Global Navigation Satellite System Reflectometry (GNSS-R) technique with high spatio-temporal resolution offers a new solution to the dynamic monitoring of flood inundation. Considering the high sensitivity of GNSS-R signals to flooding, this paper proposes a dual-branch neural network (DBNN) with a convolution neural network (CNN) and a back propagation (BP) neural network for flood monitoring. The CNN module is used to automatically extract the abstract features from delay-Doppler maps (DDMs), while the BP module is fed with GNSS-R typical features, such as surface reflectivity and power ratio, as well as vegetation information from Soil Moisture Active Passive satellite (SMAP) data. In the experiments, the superiority of the DBNN method is firstly demonstrated by comparing it with the surface reflectivity and power ratio methods. Then, the spatio-temporal variation process of the 2020 South Asian flood events is analyzed by the proposed method based on Cyclone Global Navigation Satellite System (CYGNSS) data. The understanding of flood change processes could help enhance the capacity for resisting flood disasters

Characteristics of droplet dispersion and interpersonal exposure in indoor and outdoor dining areas of urban street: Elementary numerical investigations

Indoor and outdoor dining areas are special spaces where people generally sit close and talk face-to-face for a long time (∼hour). Semi-open dining area is of popularity among them, one of the reason is the thoughts that outdoor dining area have experienced small infectious risks, even though this opinion has not been thoroughly validated yet. As a novelty, this study conducts CFD simulations to investigate droplet dispersion and face-to-face exposure risk of customers in the indoor and outdoor dining areas of typical street canyons (H/W = 1) by coupling indoor/outdoor airflows. Different scenarios are considered including index patient locations, the setting of the desk isolation board (DIB, HDIB = 0.6 m or 1.2 m), and the outdoor semi-open street roof (SSR). Results show that indoor dining spaces with single-sided ventilation experience one-order poorer ventilation (net escape velocity NEV∼0.036 m/s) and subsequently 10–200 times higher face-to-face droplet trap fraction than those in outdoor dining areas (NEV∼0.407 m/s, TF∼3–102 ppm). Indoor desk isolation board can decrease face-to-face TF by 50 %, but in outdoors, TF without desk-isolation board is 6.5 ppm for 50 μm droplet and this value changes little or slightly increases as HDIB is 0.6 m (∼8.9 ppm) or 1.2 m (∼7.7 ppm), indicating DIB seems not helpful to reduce airborne exposure risk in outdoors. Moreover, the setting of an outdoor semi-open street roof (SSR) may reduce NEV in the indoor or outdoor dining area by half or 90 % respectively. Therefore, SSR may raise indoor and outdoor customers' face-to-face exposure risk (e.g. TF) by hundreds of times and seventy times respectively