ARTICLE | doi:10.20944/preprints202309.1661.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Silk Road pattern; circumglobal teleconnection pattern; linkages and differences; interannual and interdecadal timescales
Online: 25 September 2023 (10:42:37 CEST)
The Silk Road pattern (SRP) and Circumglobal teleconnection pattern (CGT) are two well-known teleconnection patterns along the Eurasian westerly jet during boreal summer, which are often regarded as one teleconnection pattern. In view of the distinct features of the SRP/CGT on the interannual (IA) and interdecadal (ID) timescales, the present study investigates the linkages and differences between the SRP and CGT on the two timescales. On the IA timescale, the SRP and CGT feature a similar circumglobal wave train structure with strong and significant centers over Eurasia, but show clear independences. Specifically, the SRP and CGT illustrates largely the mid-/high-latitude-related and tropics-related parts of the Northern Hemisphere upper-tropospheric circulation variations, respectively. Also, the CGT shows a stronger connection to the Indian summer monsoon (ISM) heating and El Niño–Southern Oscillation than the SRP, which makes the CGT more like a tropical-forcing-driven atmospheric mode but the SRP more like an internal atmospheric mode. The linkages and differences between them are associated with their asymmetry relationship during their positive and negative phases, which are attributed mainly to the asymmetry impact of the ISM heating/cooling on the Eurasian circulations. On the ID timescale, the SRP and CGT are characterized by a coherent two-wave train structure over Eurasia, and feature more like the same teleconnection pattern, which are associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation. The present findings on the linkages and differences between the SRP and CGT are helpful to understand the variability and prediction of the SRP and CGT.
ARTICLE | doi:10.20944/preprints202303.0133.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Photonic crystal fiber; Gas; Sensitivity; Confinement loss; Characteristic
Online: 7 March 2023 (09:43:50 CET)
A total internal reflection photonic crystal fiber (PCF) based on hexagonal core is proposed for gas sensing in a specific wavelength range. The higher sensitivity and lower confinement loss were realized by the structure of the proposed PCF consists of two layers with circular holes rotated hexagonally around a core region and six slotted air-hole in the cladding based on numerical analysis. The simulation results show that the enhancement of the relative sensitivity has been done by enhancing the diameter of the hexagonal shape air-hole cladding (d1) and the hexagonal arranged holes around the central solid core (d0) in this design. Also, the confinement loss has been reduced by enhancing the ratio of length to width of slotted holes (l/w) and decreasing the cladding air-hole diameters (d1). As the refractive index increases, the wavelength shifts toward the long wavelength. And in a certain temperature range, the transmission characteristics of the device does not change with the temperature. The results are helpful for designing high performance PCF for gas sensing applications.
REVIEW | doi:10.20944/preprints202207.0364.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: cover crops; environment; scientometrics; network analysis
Online: 25 July 2022 (09:21:14 CEST)
This study examined the last four decades of the existing academic literature related to the environmental impacts of using cover crops in agricultural production systems. Data were collected from the Web of Science database, resulting in a sample of 3,246 peer-reviewed articles published between 1980 and 2021. We combined two advanced scientometrics analysis software (i.e., CiteSpace 6.0.R1 and Gephi 0.9.2) to identify the trajectory of the literature, hotspots, and frontiers. We developed authorship-, institution-and country-levels networks to examine academic cooperation over the last forty years. Our findings revealed that the number of peer-reviewed outputs documenting the environmental effects of cover crops has consistently increased, with a notable rise in publications between 2015 and 2021. Eighteen salient research topics were identified in the literature, including winter cover crops' effects on soil health, cover crops' effects on nitrous oxide emissions, and the relationship between cover crops and nitrate leaching. Based on the citation-clustering analysis, the trajectory of the literature may be divided into three stages. Studies in Stage 1_A (1980-2000) mainly assessed the role of cover crops in nitrogen management. In Stage 1_B (2001-2010), the research evaluated the impact of using different cover crop mixtures on farming systems. In Stage 2 (2011-2021), studies primarily addressed the environmental impacts of cover crops, particularly their effects on physical and chemical soil properties. Finally, the countries with the most outputs were the United States, Brazil, and Spain. The U.S. Department of Agriculture-Agricultural Research Service was the main contributor to the literature on the environmental impacts of cover crops.
ARTICLE | doi:10.20944/preprints202302.0358.v1
Subject: Social Sciences, Sociology Keywords: environmental knowledge; pollution; rural women; health; China
Online: 21 February 2023 (09:31:19 CET)
Rural women in developing nations are especially vulnerable to higher health risks due to environmental pollution exposure and are more likely to experience poorer health outcomes. Using data from the 2013 China General Social Survey CGSS2013, this study empirically examined the relationship among environmental knowledge (EK), pollution, health investment, and health status of women residing in rural regions in China. We employed a nationally representative sample of 1,930 female individuals for our analysis. Our results showed that the level of EK for women in rural China significantly impacted their self-reported physical and mental health. In order to account for potential endogeneity due to mutual causality, this study employed television usage and network usage as two instrument variables (IVs) of EK. We performed an IV-probit method to correct the estimated errors due to endogeneity. Additionally, to assess the reliability and robustness of our results, we re-estimated our model by replacing health status with the variable Body Mass Index (BMI). The results were consistent, providing evidence of robustness. Additionally, we examined the relationship between health investment (holding and purchasing a public health insurance policy, engaging in frequent physical activity, and acquiring commercial insurance) and health status. Our results indicate that the level of EK had no significant impact on participating in the new rural cooperative medical system. However, the preference of purchasing commercial insurance was positively impacted by EK, though it does not have a direct impact on the health condition. Conversely, an increase in EK and pollution is associated with a greater likelihood of engaging in physical exercise, which could, in turn, improve overall mental health.
ARTICLE | doi:10.20944/preprints202306.0354.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: synthesis; CsPbX3; perovskite nanocrystals
Online: 5 June 2023 (16:35:12 CEST)
Compared with conventional semiconductors, halide perovskite nanocrystals (NCs) have a unique crystal structure and outstanding optoelectronic properties, which offer a wide potential for applications in optoelectronic devices such as solar cells, photodetectors, light emitting diodes, lasers and displays. Rational technological design is providing vital support for the development of perovskite optoelectronics. Herein, high-quality and monodisperse all-inorganic halide perovskite nanocrystals with consistent morphology, concentrated size distribution and cubic crystal phase were synthesized employing a modified one-pot hot injection method to independently modulate the stoichiometric ratios of three precursors involving cesium salt, lead source and halide. Mixing two kinds of perovskite NCs with different halogens, in combination with an anion exchange reaction, enables a transition from violet emission to green and finally to red emission over the entire visible region. Our work will be applied to enhance optoelectronic properties and stability of all-inorganic perovskite NCs for serving as light-emitting components in optoelectronic devices, as well as expanding the application areas of perovskite semiconductors for photocatalytic hydrogen generation, CO2 reduction and dye degradation.
ARTICLE | doi:10.20944/preprints202305.0344.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: machine learning; thermodynamic calculations; martensitic aged steel; mechanical properties
Online: 5 May 2023 (10:04:31 CEST)
This paper mainly used database technology, machine learning, thermodynamic calculation, experimental verification, etc., on integrated computational materials engineering. The interaction between different alloying elements and the strengthening effect of precipitated phases are investigated mainly for martensitic ageing steels. Modelling and parameter optimization were performed by machine learning, and the highest prediction accuracy was 98.58%. Investigated the influence of composition fluctuation on performance and correlation tests to analyze the influence of elements from multiple perspectives. Furthermore, screen out the three-component composition process parameters with composition and performance with high contrast. Thermodynamic calculations studied the effect of alloying element content on the nano-precipitation phase, Laves phase, and austenite in the material. The heat treatment process parameters of the new steel grade were also developed based on the phase diagram. A new type of martensitic ageing steel was prepared by selected vacuum arc melting. The sample with the highest overall mechanical properties had a yield strength of 1887 MPa, a tensile strength of 1907 MPa, and a hardness of 58 HRC. The sample with the highest plasticity had an elongation of 7.8%. The machine learning process for the accelerated design of new ultra-high tensile steels was found to be generalizable and reliable.
ARTICLE | doi:10.20944/preprints202306.0442.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: perovskite; core-shell; heterostructure; stability; photocatalyst
Online: 6 June 2023 (10:13:35 CEST)
Practical applications of CsPbX3 nanocrystals (NCs) are limited by their poor stability. The formation of heterojunction between CsPbX3 NCs and oxides is an effective means to protect perovskite from polar solvents and other external factors. Significantly improving the stability and photocatalytic properties of the core/shell perovskite is very important for its application in photoelectric and photocatalytic technology. Here, we report the synthesis of asymmetrical CsPbBr3/TiO2 core-shell heterostructure NCs at single particle level by hot injection liquid phase synthesis and sol-gel method, where each CsPbBr3 NCs is partially covered by titanium dioxide. It is shown that the type II arrangement is generated at the heterogeneous interface, which greatly facilitates the separation of electron-hole pairs and increases the carrier transport efficiency. More crucial, due to the protection of titanium dioxide shell, the product has higher long-term stability in humid air compared with bare CsPbBr3 NCs. The asymmetrical core-shell heterostructure prepared in this study not only improves the stability of CsPbX3 NCs, but also provides some ideas for optoelectronic device applications and TiO2-based photocatalysts.
ARTICLE | doi:10.20944/preprints202309.1580.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: Z-scheme; Tetracycline; Photocatalysis; ZnFe2O4; ZnO
Online: 22 September 2023 (13:39:00 CEST)
The development of photocatalysts with a wide spectral response and effective carrier separation capability is essential for the green degradation of tetracycline. In this work, a magnetic recyclable Z-scheme ZnO/ZnFe2O4 heterojunction (ZZF) was successfully constructed by the solid phase method using MIL-88A(Fe)@Zn as the precursor. Appropriate band gap width and Z-scheme charge transfer mechanism make ZZF have excellent visible light absorption performance, efficient charge separation and strong redox ability. Under visible light irradiation, the degradation efficiency of TCH for optimal sample ZZF2 can reach 86.3 % within 75 min in deionized water, and achieve 92.9 % within 60 min in tap water, which exhibits superior stability and reusability after five cycles. Moreover, the catalyst in the water can be conveniently recovered by magnetic force. After visible light irradiation for 70 minutes, the temperature of the reaction system increased by 21.9 °C. Its degradation constant (35.53×10-3 min-1) increases 5.1 times that at room temperature (6.95×10-3 min-1). Thermal energy perfects the kinetic driving force of the reactants and promotes carrier migration to produce more •O2- and •OH. This work provides a potential candidate and inspires the design of photocatalyst for tetracycline hydrochloride degradation.
Subject: Medicine And Pharmacology, Epidemiology And Infectious Diseases Keywords: COVID-19; SARS-CoV-2; epidemic dynamics; disease control; clinical features; tropical area
Online: 8 July 2020 (12:30:52 CEST)
Objective: The objective of this study is to determine the epidemic dynamics and clinical features of COVID-19 in southern Hainan Island, China, and provide experience for other tropical areas of the world. Methods: This retrospective study included confirmed cases of COVID-19 in southern Hainan. All enrolled patients were treated in Sanya, and data on epidemiological and clinical features of the disease and infection prevention and control measures adopted by the local government during the epidemic were collected. Results: Of the 74 cases, 71 (95.95%) were imported from Wuhan, Hubei Province (47, 63.51%), other cities in Hubei Province (11, 14.86%), or provinces other than Hubei and Hainan (13, 17.57%). Three (4.06%) patients were infected in southern Hainan, including one autochthonous case in Sanya. Fifty-four cases (72.97%) were detected in Sanya, and 27 cases (27.03%) were diagnosed in other cities. The rate of severe or critical cases was 28.38% (21/74), and mortality was 2.7% (2/74). The serum lactate levels and base excess of severe-critical patients were higher than those of patients with mild-moderate disease. Multivariate logistic regression analysis showed that chronic conditions were risk factors for severe and critical COVID-19. Seventy-four patients were diagnosed with COVID-19 over a 22-day period in Sanya, and the epidemic period in the city was 48 days. The outbreak was controlled rapidly because the local government adopted strict infection prevention and control measures. Conclusions: The clinical characteristics of COVID-19 in Hainan Island were similar to those reported in other regions. In Sanya, the rate of severe and very severe cases was higher than in other regions; however, most cases were imported, and there was only one autochthonous case. The rapid control of the outbreak in Sanya may be related to the tropical climate, adoption of strict infection prevention and control measures, daily reporting of new cases, increased public awareness about the epidemic, and other emergency actions implemented by the local government.