Enhancing the number of modes in metasurfaced reverberation chambers for field uniformity improvement

The use of metasurfaces to increase the number of modes, lower the operating frequency, and improve the field uniformity in reverberation chambers (RCs) is investigated in this paper. The method used to improve the field uniformity and decrease the resonance frequencies is based on increasing the number of modes by using the concept of subwavelength cavities. The resonance frequencies of a RC with metasurface wall are derived and expressed analytically in terms of macroscopic characteristics. Simulation of the reflection phase of the unit cell is then given as a guideline to choose the required microscopic parameters of the designed metasurface. The mode density in such subwavelength RCs is then obtained using a numerical eigenmode solver. Compared to traditional RCs, a much higher modal density is obtained at low frequencies. The standard deviation of the field uniformity in the test volume of the RC corresponding to different types of metasurface walls is finally compared. It is shown that by increasing the number of modes in the RC at the lower band, the operating frequency decreases and the field uniformity of the RC is improved

Optimal planting pattern of cotton is regulated by irrigation amount under mulch drip irrigation

ObjectiveIt is of great importance to explore agronomic management measures for water conservation and cotton yield in arid areas.MethodsA four–year field experiment was conducted to evaluate cotton yield and soil water consumption under four row spacing configurations (high/low density with 66+10 cm wide, narrow row spacing, RS66+10H and RS66+10L; high/low density with 76 cm equal row spacing, RS76H and RS76L) and two irrigation amounts (CI:conventional drip irrigation; LI:limited drip irrigation) during the growing seasons in Shihezi, Xinjiang.ResultsA quadratic relationship was observed between the maximum LAI (LAImax) and seed yield. Canopy apparent transpiration rate(CAT), daily water consumption intensity (DWCI) and crop evapotranspiration (ETC) were positively and linearly correlated with LAI. The seed yields, lint yields, and ETC under CI were 6.6–18.3%,7.1–20.8% and 22.9–32.6%higher than those observed under LI, respectively. The RS66+10H under CI had the highest seed and lint yields. RS76L had an optimum LAImax range, which ensured a higher canopy apparent photosynthesis and daily dry matter accumulation and reached the same yield level as RS66+10H; however, soil water consumption in RS76L was reduced ETC by 51–60 mm at a depth of 20–60 cm at a radius of 19–38 cm from the cotton row,and water use efficiency increased by 5.6–8.3%compared to RS66+10H under CI.ConclusionA 5.0<LAImax<5.5 is optimum for cotton production in northern Xinjiang, and RS76L under CI is recommended for high yield and can further reduce water consumption. Under LI, the seed and lint yield of RS66+10H were 3.7–6.0% and 4.6–6.9% higher than those of RS76L, respectively. In addition, high-density planting can exploit the potential of soil water to increase cotton yields under water shortage conditions

Biogeographic patterns and drivers of soil viromes

Viruses are crucial in shaping soil microbial functions and ecosystems. However, studies on soil viromes have been limited in both spatial scale and biome coverage. Here we present a comprehensive synthesis of soil virome biogeographic patterns using the Global Soil Virome dataset (GSV) wherein we analysed 1,824 soil metagenomes worldwide, uncovering 80,750 partial genomes of DNA viruses, 96.7% of which are taxonomically unassigned. The biogeography of soil viral diversity and community structure varies across different biomes. Interestingly, the diversity of viruses does not align with microbial diversity and contrasts with it by showing low diversity in forest and shrubland soils. Soil texture and moisture conditions are further corroborated as key factors affecting diversity by our predicted soil viral diversity atlas, revealing higher diversity in humid and subhumid regions. In addition, the binomial degree distribution pattern suggests a random co-occurrence pattern of soil viruses. These findings are essential for elucidating soil viral ecology and for the comprehensive incorporation of viruses into soil ecosystem models

The Three-Dimensional Locating of VHF Broadband Lightning Interferometers

VHF (Very High Frequency) lightning interferometers can locate and observe lightning discharges with a high time resolution. Especially the appearance of continuous interferometers makes the 2-D location of interferometers further improve in time resolution and completeness. However, there is uncertainty in the conclusion obtained by simply analyzing the 2-D locating information. Without the support of other 3-D total lightning locating networks, the 2-station interferometer becomes an option to obtain 3-D information. This paper introduces a 3-D lightning location method of a 2-station broadband interferometer, which uses the theodolite wind measurement method for reference, and gives the simulation results of the location accuracy. Finally, using the multi-baseline continuous 2-D locating method and the 3-D locating method, the locating results of one intra-cloud flash and the statistical results of the initiation heights of 61 cloud-to-ground flashes and 80 intra-cloud flashes are given. The results show that the two-station interferometer has high observation accuracy on both sides of the connection between the two sites. The locating accuracy will deteriorate as the distance between the radiation source and the two stations increases or the height decreases. The actual locating results are similar to those of the existing VHF TDOA (Time Difference of Arrival) lightning locating network

Is methane a new therapeutic gas?

<p>Abstract</p> <p>Background</p> <p>Methane is an attractive fuel. Biologically, methanogens in the colon can use carbon dioxide and hydrogen to produce methane as a by-product. It was previously considered that methane is not utilized by humans. However, in a recent study, results demonstrated that methane could exert anti-inflammatory effects in a dog small intestinal ischemia-reperfusion model.</p> <p>Point of view</p> <p>Actually, the bioactivity of methane has been investigated in gastrointestinal diseases, but the exact mechanism underlying the anti-inflammatory effects is required to be further elucidated. Methane can cross the membrane and is easy to collect due to its abundance in natural gas. Although methane is flammable, saline rich in methane can be prepared for clinical use. These seem to be good news in application of methane as a therapeutic gas.</p> <p>Conclusion</p> <p>Several problems should be resolved before its wide application in clinical practice.</p

Association of ACEI/ARB, inflammatory cytokines, and antiviral drugs with liver dysfunction in patients with hypertension and COVID-19

Background: Currently, SARS-CoV-2 liver invasion, inflammatory cytokines, and antiviral drugs are widely thought to be associated with liver dysfunction in COVID-19 patients. Besides, previous studies indicated that ACEI/ARB drugs can increase the expression of hepatic ACE2, a cell entry receptor for SARS-CoV-2. This study aims to investigate whether ACEI/ARB aggravates liver injury and the association of inflammatory cytokines and antiviral drugs with liver dysfunction in patients with hypertension and COVID-19.Method: This retrospective study included 127 hypertensive patients with long-term use or nonuse of ACEI/ARBs hospitalized for COVID-19 from January 30 to April 7, 2020, in Tongji hospital of Wuhan, China. Demographic, clinical, laboratory, treatment, and outcome data were collected.Results: Of the 127 patients with COVID-19 and hypertension, 43 taking long-term of ACEI/ARBs and 84 without using ACEI/ARBs. Abnormal liver function was observed in part of ACEI/ARB and non-ACEI/ARB users but without significant differences between these two groups. Serum inflammatory cytokines, IL-6, IL-8, and TNFα, as well as inflammation-related markers, ferritin, procalcitonin, and C-reactive protein, were significantly elevated in patients with liver dysfunction. IL-6 level was positively correlated with liver function tests on admission and highly consistent with the changes of abnormal ALT, AST, and GGT during hospitalization, but the correlations of other inflammatory cytokines were low. There was no significant association between the use of antiviral drugs and liver dysfunction in these patients.Conclusion: The elevation of inflammatory cytokine, IL-6, but not ACEI/ARB and antiviral drugs, is closely associated with liver dysfunction in patients with hypertension and COVID-19

Simple microwave preparation of high activity Se-rich CoSe2/C for oxygen reduction reaction

Carbon supported cobalt selenide (CoSe2/C) nanoparticles were prepared by a simple microwave method using cobalt acetate and selenium dioxide as precursors with different molar ratios of Se/Co. The effects of Se/Co ratios on surface morphology, crystal structure, chemical composition and electrocatalytic activity toward oxygen reduction reaction (ORR) of CoSe 2/C catalyst nanoparticles were systematically investigated. It was found that the experimental compositions of CoSe1.8/C～CoSe 2.7/C with average crystallite sizes of 15.4～12.9 nm were obtained with the Se/Co ratios of 2.0～4.0. The major phases of CoSe 2/C nanoparticles were identified to be orthorhombic CoSe2 with minor cubic CoSe2. The potentials corresponding to ORR (E ORR) reached 0.6～0.7 V, while the electron transfer numbers (n) were 3.1～4.0 in oxygen saturated sulfuric acid solutions. The formation of Se-rich CoSe2/C nanoparticles was confirmed with Se/Co ≥ 2.5, and the best ORR activities with EORR = 0.705 V and n = 4.0 could be achieved with Se/Co = 3.0. Slightly excess amount of Se oxide presented in CoSe2/C would prevent CoSe2 nanoparticles from growing and smaller sizes with less agglomerated Se-rich CoSe2/C were obtained, resulting in good ORR activity. However, too much Se oxide would cause severe aggregation of CoSe2 nanoparticles, leading to poor ORR activity. ? 2014 Elsevier Ltd

Characteristics of Regions with High-Density Initiation of Flashes in Mesoscale Convective Systems

To investigate the characteristics of regions exhibiting multiple lightning initiations within a finite volume and a short time, the lightning location data obtained from the convective regions of 14 mesoscale convective systems were analyzed in combination with data from radar. In total, 415 out of 5996 radar grids (1 km &times; 1 km &times; 0.5 km) were found to initiate more than one flash within 6 min. Only 49 grids showed an initiation density of more than two flashes within 6 min. The grids with high flash initiation densities were found to have a similar distribution to those with one lightning initiation within 6 min, in terms of altitude and reflectivity relative to altitude. They also showed similar trends in their frequency evolution. The grids with higher initiation densities seemed to be more concentrated in the altitude range of 9&ndash;13 km. However, only one was found to form at a lower altitude near the melting level when lightning initiation clearly declined. Moreover, the spatial relationship of this lower higher-initiation density grid to the reflectivity core was different to that in the main altitude range. In this paper, the possible dynamic and electrical mechanisms of the formation of this lower higher-initiation density grid are discussed

Protective Effects of Elaeagnus angustifolia Leaf Extract against Myocardial Ischemia/Reperfusion Injury in Isolated Rat Heart

The purpose of this study is to clarify the cardioprotective property of the aqueous extract of Elaeagnus angustifolia L. leaf (EA) against myocardial ischemia/reperfusion injury in isolated rat heart. The myocardial ischemia/reperfusion (I/R) injury model of isolated rat heart was set up by the use of improved Langendorff retrograde perfusion technology. Compared with the ischemia/reperfusion (I/R) group, the aqueous extract of Elaeagnus angustifolia L. leaf (0.5 mg/mL, 1.0 mg/mL) pretreatment markedly improved the coronary flow (CF) and raised left ventricular developed pressure (LVDP) and maximum rise/down velocity (±dp/dtmax). The infarct size of the EA-treated hearts was smaller than that of I/R group. After treatment with EA, the superoxide dismutase (SOD) activity increased; malondialdehyde (MDA) and protein carbonyl content reduced more obviously (P<0.01) than that of I/R injury myocardial tissue. Conclusion. Results from the present study showed that the aqueous extract of Elaeagnus angustifolia L. leaf has obvious protective effects on myocardial I/R injury, which may be related to the improvement of myocardial oxidative stress states