Search

We report the properties of more than 600 bursts (including cluster-bursts) detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during an extremely active episode on UTC September 25-28, 2021, in a series of four papers. The observations were carried out in the band of 1.0 - 1.5 GHz by using the center beam of the L-band 19-beam receiver. We monitored the source in sixteen 1-hour sessions and one 3-hour session spanning 23 days. All the bursts were detected during the first four days. In this first paper of the series, we perform a detailed morphological study of 624 bursts using the 2-dimensional frequency-time ``waterfall'' plots, with a burst (or cluster-burst) defined as an emission episode during which the adjacent emission peaks have a separation shorter than 400 ms. The duration of a burst is therefore always longer than 1 ms, with the longest up to more than 120 ms. The emission spectra of the sub-bursts are typically narrow within the observing band with a characteristic width of $\sim$277 MHz. The center frequency distribution has a dominant peak at about 1091.9 MHz and a secondary weak peak around 1327.9 MHz. Most bursts show a frequency-downward-drifting pattern. Based on the drifting patterns, we classify the bursts into five main categories: downward drifting (263) bursts, upward drifting (3) bursts, complex (203), no drifting (35) bursts, and no evidence for drifting (121) bursts. Subtypes are introduced based on the emission frequency range in the band (low, middle, high and wide) as well as the number of components in one burst (1, 2, or multiple). We measured a varying scintillation bandwidth from about 0.5 MHz at 1.0 GHz to 1.4 MHz at 1.5 GHz with a spectral index of 3.0., Comment: Accepted by Research in Astronomy and Astrophysics (RAA)

In the present study, the Mg-4Zn-0.6Y-0.5Nd alloy was hot extruded and annealed at 200°C, 225°C and 250°C for different time to optimize microstructure and mechanical properties. The results exhibit that the dual-size grain structure and linearly distributed secondary phase are the main feature of the as-extruded Mg-Zn-Y-Nd alloy, which can be described as the elongated grain is surrounded by the fine equiaxed grain. Moreover, the as-extruded alloy shows strong { 01 1 ¯ 0 } fiber texture feature, especially for the large elongated grains. The annealing treatment results in static recrystallization, which increases fine equiaxed grains but decreases large elongated grains. In addition, the equiaxed grains formed during the annealing treatment demonstrate relative random orientations, which weaken the { 01 1 ¯ 0 } fiber texture of the alloy. Moreover, during the annealing at 225°C and 250°C, the extension twins begin to form in the alloy and weaken the { 01 1 ¯ 0 } fiber texture of the alloy further. The annealing treatment has little influence on the linearly distributed secondary phase but promotes the coarsening of small precipitates at 250°C. The annealing treatment could increase the yield and ultimate strength, but the elongation decreases, especially at higher temperature. Such a variation can be ascribed to the evolution of texture, grain structure, twinning and precipitation during the annealing treatment.

Background Delirium is common in elderly patients after surgery and is associated with poor outcomes. This study aimed to investigate the impact of intraoperative dexmedetomidine on the incidence of delirium in elderly patients undergoing major surgery. Methods This was a randomized double-blind placebo-controlled trial. Elderly patients (aged 60 years or more) scheduled to undergo major non-cardiac surgery were randomized into two groups. Patients in the intervention group received a loading dose of dexmedetomidine 0·6 μg/kg 10 min before induction of anaesthesia followed by a continuous infusion (0·5 μg per kg per h) until 1 h before the end of surgery. Patients in the control group received volume-matched normal saline in the same schedule. The primary outcome was the incidence of delirium during the first 5 days after surgery. Delirium was assessed with the Confusion Assessment Method (CAM) for non-ventilated patients and CAM for the Intensive Care Unit for ventilated patients. Results In total, 309 patients who received dexmedetomidine and 310 control patients were included in the intention-to-treat analysis. The incidence of delirium within 5 days of surgery was lower with dexmedetomidine treatment: 5·5 per cent (17 of 309) versus 10·3 per cent (32 of 310) in the control group (relative risk (RR) 0·53, 95 per cent c.i. 0·30 to 0·94; P = 0·026). The overall incidence of complications at 30 days was also lower after dexmedetomidine (19·4 per cent (60 of 309) versus 26·1 per cent (81 of 310) for controls; RR 0·74, 0·55 to 0·99, P = 0·047). Conclusion Intraoperative dexmedetomidine halved the risk of delirium in the elderly after major non-cardiac surgery. Registration number: ChiCTR-IPR-15007654 (www.chictr.org.cn).

This study reports a relation between electron flux modulations and chorus emissions by using correlation analysis. On April 18, 2017, Arase observed an enhancement of electron fluxes and intensification of banded chorus emissions at the same time. A result of the analysis shows that both the upper-band and lower-band chorus emissions have good correlations with field-aligned electron fluxes that satisfy their resonance conditions. This indicates simultaneous interactions with both the emission bands and electrons, resulting in electron pitch-angle scattering toward the magnetic field direction. In addition, low-energy electron fluxes in the perpendicular direction also show positive correlations with the chorus intensities, probably because the chorus emissions are modulated by a fluctuation of perpendicular low-energy electron fluxes.

The degree of tree-crop competition for nitrogen (N) and its effect on fertilizer-use efficiency and N movement were examined in a jujube tree (Zizyphus jujuba Mill.)/wheat (Triticum aestivum Linn.) agroforestry system during 2011–2012. Assessment of competition was accomplished via the installation of an experiment with five imbedding depths (20, 40, 80, 120 and 200 cm) of 15N-enriched CO(NH2)2 and two configuration patterns (sole and intercropped treatment). The percentage of N derived from fertilizer (NDFF) and fertilizer-use efficiency (UFN) were determined using 15N-enriched CO(NH2)2 (5.22% atom enrichment) applied at 8 g N per plant. Land equivalent ratios of the jujube/wheat intercropping system reached maximum ratios of 1.45 for grain (fruit) yield and 1.67 for biomass in 2011 and 1.38 for grain (fruit) yield and 1.59 for biomass in 2012. The alley cropping yield decreased significantly compared to sole-cropped plants in both years, as did the biomass of intercropped wheat in 2012. This study showed a significant difference in nitrogen acquisition between intercropping and the expected value for the various depths in both years. The %NDFF of the two plants showed significant differences between intercropping and the expected value at various depths in both years, and the intercropped %NDFF was higher than the expected value. The total UFN data, which represented an increase in response to intercropping, indicate that plants in the intercropping treatment had a higher UFN than the expected value. The UFN for jujube trees in all treatments was lower than that for wheat, indicating less uptake and utilization of N fertilizer. Management interventions, particularly those that increase fertilizer in the shallow layer may be critical for the success of this system.

Coronavirus disease 2019 (COVID-19) outbroke in Wuhan, China in December 2019 and the severe acute respiratory syndrome (SARS) outbroke in Guangzhou, China in 2003 were caused by highly pathogenic coronaviruses with high homology. Since the 2019 novel coronavirus is highly contagious and spreads rapidly. It has caused negative social effects and massive economic loss globaly. Currently there is no vaccine or effective drugs. Pulmonary fibrosis is a pulmonary disease with progressive fibrosis, which is the main factor leading to pulmonary dysfunction and declined quality of life in SARS survivors after recovery. Extensive epidemiological, viral immunological and current clinical evidences support the possibility that pulmonary fibrosis may be one of the major complications in COVID-19 patients. At present there is no report on the mechanism by which COVID-19 induces pulmonary fibrosis.With the existing theoretical basis, this article focuses on discussing the possible mechanism of COVID-19 sustained lung damaging, the key role of abnormal immune mechanism in the initiation and promotion of pulmonary fibrosis, and the corresponding therapeutic measures.2019年12月暴发于中国武汉的新型冠状病毒肺炎(COVID-19)与2003年暴发于中国广州的严重急性呼吸综合征(SARS)是由同源性较高的高致命性冠状病毒导致的。新型冠状病毒传播性强、进展迅速，在全球范围内造成不良的社会影响和巨大经济损失，但目前尚无针对COVID-19的疫苗或特效药物。肺纤维化是一种进行性纤维化的肺部疾病，是导致SARS幸存者愈后肺功能障碍及生存质量下降的主要因素。大量流行病学、病毒免疫学及目前的临床证据支持肺纤维化有可能成为COVID-19患者的严重并发症之一。目前暂无关于COVID-19引发肺纤维化的机制的报道，本文就现有理论依据重点讨论COVID-19肺部持续损伤的可能机制、异常免疫机制在引发和促进肺纤维化中的关键作用以及相关治疗措施。.

Planting trees near crops can diversify the landscape, provide pollinators for crops, and allow predators to control insect pests. However, trees can also compete with crops for light, water, and nutrients. Field experiment at the Shihezi Oasis in northern Xinjiang Province assessed the effects of distance on photosynthetic characteristics and yield of wheat in a jujube tree (Zizyphus jujuba Mill.)/wheat (Triticum aestivum L.) agroforestry system. The experiment used two treatments: a control of sole-cropped wheat (D0) and a jujube tree/wheat agroforestry system. The agroforestry system included the different distances of 90, 110, and 130 cm (D1, D2, and D3, respectively) between the wheat and the jujube trees. Photosynthetic characteristics, leaf area index (LAI), the number of stems, and yield components of wheat were determined. The net photosynthetic rate (Pn) and the stomatal conductance (Gs) of the D0, D2, and D3 during the filling stage were significantly higher than the D1. No significant difference in transpiration rate (Tr) and intercellular CO2 concentration (Ci) was noted between sole-cropped wheat and agroforestry system. From the tillering to ripening stages, significant differences were observed in stem, tiller number, and dry matter accumulation per plant, and in LAI, which ranked D0 > D3 > D2 > D1. D0 and D3 plants had significantly higher numbers of spikes, grains per spike, and weight of thousand grains than D1 and D2 plants. The crop yield was ranked as D0 > D3 > D2 > D1, with significant differences among D0, D1, D2, and D3. In conclusion, wheat yield increased as the distance from jujube trees increased in this jujube tree/wheat intercropping system.

Mg–Zn–Y–Nd alloy was prepared by casting and hot extrusion. The microstructure and mechanical properties of OM, SEM, XRD, TEM, and tensile tests were investigated with casting and hot extruded alloys. The results demonstrate that in a casting Mg–Y–Nd–Zr alloy, the α-Mg matrix is separated into the cell structure by a discontinuously distributed coarse Mg24Y5/α-Mg eutectic structure and fine Mg12Nd particles. TEM analysis shows that the Mg12Nd and Mg24Y5 phases have the orientation of $$ {\left[001\right]}_{{\mathrm{Mg}}_{12}\mathrm{Nd}}//{\left[0221\right]}_{\upalpha -\mathrm{Mg}} $$ , and $$ {\left[111\right]}_{{\mathrm{Mg}}_{24}{\mathrm{Y}}_5}//{\left[0001\right]}_{\upalpha -\mathrm{Mg}} $$ and $$ {\left(10\overline{1}\right)}_{{\mathrm{Mg}}_{24}{\mathrm{Y}}_5}//{\left(10\overline{1}0\right)}_{\upalpha -\mathrm{Mg}} $$ , respectively. The hot extrusion separates the Mg24Y5/α-Mg eutectic structure into fragments and aligns fragmentary Mg24Y5 particles along the extrusion direction. The interaction of hot extrusion and strengthening particles refines the α-Mg matrix greatly. Moreover, large strains result in the stacking faults of the matrix. As compared to the casting alloy, the hot-extruded one exhibits high yield strength, ultimate tensile strength, and elongation, which should be ascribed to the grain fineness, optimum distribution of strengthening particles and multiple substructures.

In this paper, combined with the wind farm blade failure cases, the blade failure reasons are analyzed from the aspects of blade design, material performance, manufacturing quality, transportation and hoisting, online monitoring, wind farm operation, and maintenance. In order to prevent blade operation failure, measures and suggestions based on blade selection, supplier selection, operation and maintenance management are proposed, which provide methods for blade design, manufacturing, and production maintenance.

Effects of tree shading on crops within an agroforestry system in Hetian oasis regions in northwestern China are poorly understood. Measurements of light intensity, light use efficiency (LUE), light extinction coefficient, leaf area index (LAI), crop yield and biomass were studied in determining the effects of tree shading on crop yield in a jujube (Zizyphus jujuba Mill.)/wheat (Triticum aestivum L.) intercropping system. The treatments comprised (1) sole-cropped wheat, (2) 6-year-old sole jujube trees, (3) 8-year-old sole jujube trees, (4) 10-year-old sole jujube trees, (5) intercropping of wheat/6-year-old jujube trees, (6) intercropping of wheat/8-year-old jujube trees and (7) intercropping of wheat/10-year-old jujube trees. We found that the land equivalent ratios (LERs) of all three jujube tree/wheat treatments were larger than one and this indicated that plant growth factors were used more efficiently by the intercrop than by sole crops and the land use advantages of the intercropping systems were significantly greater than monoculture crops. Because of shading by trees, there was a decrease in intercropped wheat LAI, growth and yield, and the fruit yield of the intercropped jujube trees also decreased to a certain degree. The light interception of intercropped wheat was significantly decreased by different tree ages up to a certain point. The LUE results ranged from 1.68 to 1.31 and 1.13 g DM MJ [photosynthetically active radiation (PAR)]−1, indicating that LUE can be significantly affected by increasing tree age. Compared to intercropping 8-year-old jujube trees, a higher light extinction coefficient was found in intercropping 6- and 10-year-old jujube trees.

A field study was conducted at Hetian oasis, southern Xinjiang, northwestern China, to investigate root distribution and morphology affected by interspecific interactions between jujube trees (Ziziphus jujuba Mill.) and cotton plants (Gossypium hirsutum L.). The treatments comprised (1) sole cotton, (2) 5-year-old sole jujube trees, (3) 7-year-old sole jujube trees, (4) 9-year-old sole jujube trees, (5) intercropping of cotton/5- year-old jujube trees, (6) intercropping of cotton/7-year-old jujube trees, and (7) intercropping of cotton/9-year-old jujube trees. Roots in each plot were sampled vertically by auger to a depth of 100 cm at 20-cm intervals and horizontally up to 150 cm away from the base of the trees at 30-cm intervals. The results showed that all jujube/cotton intercropping systems exhibited advantages of intercropping, with a land equivalent ratio > 1. The roots of both intercropped cotton and jujube had lower root length density (RLD) and root diameter (RD) at all soil depths compared with those of sole-cropped cotton and jujube trees. Interspecific competition with jujube trees altered the root development and morphology of the cotton plants. The roots of the trees spread underneath the crop and the roots of intercropped cotton tended to have a shallower distribution in the soil profile. A greater distance from the trees resulted in less influence on the RLD and RD of intercropped cotton. Older jujube trees had more developed roots and consequently higher RLD and RD. These findings may partly explain the interspecific competition effects in jujube tree/cotton agroforestry systems. However, the mechanisms underlying the root interactions between cotton and jujube require further investigation.

The objective of this experiment was to learn more about root morphology and spatial distribution in a specify walnut (Juglans regia L.)/wheat (Triticum aestivum L.) intercropping system. The effects of intercropping on aboveground yield and land equivalent ratio (LER) were also determined. The experiment was conducted at Hetian in the southern part of the Xinjiang Uyghur Autonomous Region. The results showed that walnut/wheat intercropping reduced the aboveground yield of both component species. However, the LER of the intercropping system averaged 1.62. This meant that intercropping increased land use efficiency. Intercropping significantly reduced the root length density, root surface area density, and root diameter (RD) of both component species compared with sole-cropping. In contrast, intercropping significantly increased the specific root length of walnut. Root competition between species was the greatest in the 0–40 cm soil depth. Root competition caused uneven distribution of RD and specific root length. The plasticity of root morphology and spatial distribution is key for adapting to competition and maximizing water and nutrient uptake in walnut/wheat agroforestry systems.

The high precipitation around Southeast Asia results in abundant freshwater outflow, which transports terrestrial dissolved and particulate material to the world's largest marginal sea, namely, the South China Sea (SCS). To estimate the riverine carbon flux to the SCS, carbonate data from 42 rivers were collected. These results, combined with literature data for 13 rivers, indicate that the concentrations of dissolved inorganic carbon (DIC) are positively correlated with the cation exchange capacity and the bulk density, except for the Low Discharge category. The highest DIC concentration and flux are in the Low and Medium Discharge categories. Negative correlations exist between dissolved organic carbon (DOC) concentrations and the base saturation in the Low and High Discharge categories and between DOC and bulk density in the Low and Medium Discharge categories. However, the correlation between the DOC concentration and the organic carbon content in the soil is only significant in the Medium Discharge category. Once the negative exponential relationships between the particulate inorganic carbon (PIC) or the particulate organic carbon (POC) and the total suspended matter are determined, these can be used to estimate the PIC and POC carbon fluxes. Of the annual riverine carbon flux, 83.0 ± 8.1 Tg C, 40.14 ± 6.11 Tg is DIC, 25.03 ± 4.54 Tg is DOC, 1.83 ± 0.35 Tg is PIC, and 16.03 ± 2.87 Tg is POC. The total discharge amounts to 6.2–10.3% of the global riverine discharge for a sea covering only 1% of the world's ocean surface area and for watersheds covering only 2.2% of the global land mass.

Plague is a zoonotic disease caused by the bacterium Yersinia pestis. This pathogen can be transmitted by fleas and has an enzootic cycle, circulating among small mammals, and occasionally epizootic cycles, infecting other species. In China, infected wild rodents are primarily reservoirs of Y. Pestis and are related to human infection (Int. J. Infect. Dis., 33, 2015 and 67; BMC Microbiol., 9, 2009 and 205). Because shepherd dogs prey on and eat rodents (e.g. marmots and mice), they are valuable sentinel animals for plague serosurveillance in endemic disease foci, although their infections are usually asymptomatic (Vet. Microbiol., 172, 2014 and 339).

Transgenic Bacillus thuringiensis (Bt) crops are increasingly significant in pest control, but resistance development of target pests is a major issue in the sustainable deployment of Bt crops. The fitness cost of resistance in target pests is regarded as one of the main factors delaying resistance when adopting the refuge strategy. In this study, we compared the life-history traits of three independent sets of Helicoverpa armigera (Hübner, 1809) adults, of each there were a susceptible population and a Cry1Ac-resistant population derived by selection from it. Confirming to the previous studies, resistant individuals exhibited fewer progeny, less fecundity, lower egg hatching rate, and longer adult longevity. And poor fecundity in resistant strains was associated with the decline of the mature follicular amount, the ovarian weight ratio, and the length of the longest ovarian tubule. Interestingly, the juvenile hormone (JH) level appeared higher in resistant strains relative to susceptible strains. Application of methoprene (JH analogue) in vivo was effective in reducing fecundity and hatchability with the up-regulation of detected JH titer. These results suggested that resistance against Bt toxin reduced the reproductive capacity of H. armigera, and JH level is affected in the tradeoff between reproductive capacity and Bt resistance.

著者人数: 102名（所属. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS): 松岡, 彩子; 篠原, 育; 浅村, 和史), Accepted: 2018-12-29, 資料番号: SA1180350000

The jujube tree (Zizyphus jujuba Mill.)/wheat (Triticum aestivum L.) agroforestry system is frequently used in China’s Xinjiang Province. The system improves land-use efficiency and increases economic returns. A field experiment was conducted at the Hetian oasis in southern Xinjiang Province to investigate the relationship between root distribution and interspecific interaction between the two intercropped species. The study included seven treatments: sole-cropped 5, 7, or 9-year-old jujube trees (treatments 1–3); 5, 7, or 9-year-old jujube trees intercropped with wheat (treatments 4–6); and sole-cropped wheat (treatment 7). To determine vertical root distribution, soil cores were collected in 20-cm increments from the 0 to 100-cm soil depth. The cores were collected at horizontal distances of 30, 60, 90, 120, and 150 cm from the jujube rows. The results showed that the land equivalent ratios were >1 for the three jujube/wheat intercropping systems. This indicated that these systems were advantageous compared with sole cropping. Tree height, breast height diameter, and mean crown radius were less in the intercropped treatments than in the corresponding sole-cropped treatments. Intercropping reduced the root length densities (RLDs) and root diameters (RDs) of both jujube and wheat at all soil depths. The RLD and RD of 9-year-old jujube trees were greater than those of the 5- and 7-year-old trees, which indicated that the root systems of the 9-year-old trees were more developed. Wheat root growth was inhibited more by older jujube trees than by younger ones. In conclusion, jujube tree/wheat intercropping can be practical and beneficial in the region. However, the mechanisms involved in the belowground interspecific interactions are still unknown. Additional research is needed to provide optimal management strategies and technologies for jujube/wheat intercropping.

Ternary Cu–Sn–Sb alloys are a good candidate for solder materials without Pb element. Therefore, the knowledge of thermodynamic properties and phase transition characteristics of this alloy system is essential not only for the fundamental research but also for the industry applications. In this letter, we have measured the liquidus and solidus temperatures, enthalpy of fusion and thermal diffusivity for ternary Cu90−xSnxSb10 alloys by differential scanning calorimetry (DSC) and laser flash methods, respectively. Moreover, the typical growth morphologies of various intermetallic compounds are characterized. It is found that the primary Cu3Sn, Cu6Sn5, Cu4Sn, Cu3Sb and SnSb phases display faceted growth mode, and develop into long strips or large blocks. By contrast, the primary (Cu) phase forms by non-faceted way into very coarse dendrites.

There are many problems in the technological development, research investment, staff ability and industrialized level of domestic wind turbine blade. This review summarizes the quality situation of wind turbine blade in the production process and proposes some advices and solutions in the further development of domestic wind turbine blade.