Flexoelectricity refers to electric polarization generated by heterogeneous mechanical strains, namely strain gradients, in materials of arbitrary crystal symmetries. Despite more than 50 years of ...work on this effect, an accurate identification of its coupling strength remains an experimental challenge for most materials, which impedes its wide recognition. Here, we show the presence of flexoelectricity in the recently discovered polar vortices in PbTiO3/SrTiO3 superlattices based on a combination of machine-learning analysis of the atomic-scale electron microscopy imaging data and phenomenological phase-field modeling. By scrutinizing the influence of flexocoupling on the global vortex structure, we match theory and experiment using computer vision methodologies to determine the flexoelectric coefficients for PbTiO3 and SrTiO3. Our findings highlight the inherent, nontrivial role of flexoelectricity in the generation of emergent complex polarization morphologies and demonstrate a viable approach to delineating this effect, conducive to the deeper exploration of both topics.
Sucrose phosphate synthase (SPS) is a rate-limiting enzyme that works in conjunction with sucrose-6-phosphate phosphatase (SPP) for sucrose synthesis, and it plays an essential role in energy ...provisioning during growth and development in plants as well as improving fruit quality. However, studies on the systematic analysis and evolutionary pattern of the SPS gene family in apple are still lacking. In the present study, a total of seven MdSPS and four MdSPP genes were identified from the Malus domestica genome GDDH13 v1.1. The gene structures and their promoter cis-elements, protein conserved motifs, subcellular localizations, physiological functions and biochemical properties were analyzed. A chromosomal location and gene-duplication analysis demonstrated that whole-genome duplication (WGD) and segmental duplication played vital roles in MdSPS gene family expansion. The Ka/Ks ratio of pairwise MdSPS genes indicated that the members of this family have undergone strong purifying selection during domestication. Furthermore, three SPS gene subfamilies were classified based on phylogenetic relationships, and old gene duplications and significantly divergent evolutionary rates were observed among the SPS gene subfamilies. In addition, a major gene related to sucrose accumulation (MdSPSA2.3) was identified according to the highly consistent trends in the changes of its expression in four apple varieties (‘Golden Delicious’, ‘Fuji’, ‘Qinguan’ and ‘Honeycrisp’) and the correlation between gene expression and soluble sugar content during fruit development. Furthermore, the virus-induced silencing of MdSPSA2.3 confirmed its function in sucrose accumulation in apple fruit. The present study lays a theoretical foundation for better clarifying the biological functions of the MdSPS genes during apple fruit development.
A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs. This study was designed to determine whether optimized nitrogen ...(N) fertilization could fulfill these multiple goals. In two-year experiments, two high yielding 'super' rice cultivars were grown with different N fertilization management regimes, including zero N input, local farmers' practice (LFP) with heavy N inputs, and optimized N fertilization (ONF). In ONF, by reducing N input, increasing planting density, and optimizing the ratio of urea application at different stages, N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels. Compared with LFP, yield and partial factor productivity of applied N (PFP) under ONF were increased (on average) by 1.70 and 13.06％, respectively. ONF increased starch and amylose content, and significantly decreased protein content. The contents of the short chains of A chain (degree of polymerization (DP) 6–12) and B1 chain (DP 13–25) of amylopectin were significantly increased under ONF, which resulted in a decrease in the stability of rice starch crystals. ONF increased viscosity values and improved the thermodynamic properties of starch, which resulted in better eating and cooking quality of the rice. Thus, ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency (NUE) at high yield levels. These results will be useful for applications of high quality rice production at high yield levels.
The temperature difference between an urban space and surrounding non-urban space is called the urban heat island effect (UHI). Global terrestrial evapotranspiration (ET) can consume 1.4803×1023 ...joules (J) of energy annually, which is about 21.74% of the total available solar energy at the top of atmosphere, whereas annual human energy use is 4.935×1020 J, about 0.33% of annual ET energy consumption. Vegetation ET has great potential to reduce urban and global temperatures. Our literature review suggests that vegetation and urban agricultural ET can reduce urban temperatures by 0.5 to 4.0°C. Green roofs (including urban agriculture) and water bodies have also been shown to be effective ways of reducing urban temperatures. The cooling effects on the ambient temperature and the roof surface temperature can be 0.24-4.0°C and 0.8-60.0°C, respectively. The temperature of a water body (including urban aquaculture) can be lower than the temperature of the surrounding built environment by between 2 and 6°C, and a water body with a 16 m2 surface area can cool up to 2 826 m3 of nearby space by 1°C. Based on these findings, it can be concluded that the increase of evapotranspiration in cities, derived from vegetation, urban agriculture, and water body, can effectively mitigate the effect of urban heat islands.
Background
At present, the severity of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has been a focal point.
Methods
To assess the factors associated with ...severity and prognosis of patients infected with SARS‐CoV‐2, we retrospectively investigated the clinical, imaging and laboratory characteristics of confirmed 280 cases of novel coronavirus disease (COVID‐19) from 20 January to 20 February 2020.
Results
The median age of patients in the mild group was 37.55 years, whilst that in the severe group was 63.04 years. The proportion of patients aged over 65 years in the severe group was significantly higher than that of the mild group (59.04% vs. 10.15%, P < 0.05). 85.54% of severe patients had diabetes or cardiovascular diseases, which was significantly higher than that of the mild group (51.81% vs. 7.11%, P = 0.025; 33.73% vs. 3.05%, P = 0.042). Patients in the mild group experienced earlier initiation of antiviral treatment (1.19 ± 0.45 vs. 2.65 ± 1.06 days in the severe group, P < 0.001). Our study showed that comorbidity, time from illness onset to antiviral treatment and age >=65 were three major risk factors for COVID‐19 progression, whilst comorbidity and time from illness onset to antiviral treatment were two major risk factors for COVID‐19 recovery.
Conclusions
The elderly and patients with underlying diseases are more likely to experience a severe progression of COVID‐19. It is recommended that timely antiviral treatment should be initiated to slow the disease progression and improve the prognosis.
Blast disease caused by the fungus Magnaporthe grisea results in significant yield losses of cereal crops across the world. To date, very few regulatory genes contributing to blast resistance in ...grass species have been identified and the genetic basis of blast resistance in cereals remains elusive. Here, a core collection of foxtail millet (Setaria italica) containing 888 accessions was evaluated through inoculation with the blast strain HN-1 and a genome-wide association study (GWAS) was performed to detect regulators responsible for blast disease resistance in foxtail millet. The phenotypic variation of foxtail millet accessions inoculated with the blast strain HN-1 indicated that less than 1.60% of the samples were highly resistant, 35.25% were moderately resistant, 57.09% were moderately susceptible, and 6.08% were highly susceptible. The geographical pattern of blast-resistant samples revealed that a high proportion of resistant accessions were located in lower latitude regions where the foxtail millet growing season has higher rain precipitation. Using 720000 SNP markers covering the Setaria genome, GWAS showed that two genomic loci from chromosomes 2 and 9 were significantly associated with blast disease resistance in foxtail millet. Finally, eight putative genes were identified using rice blast-related transcriptomic data. The results of this work lay a foundation for the foxtail millet blast resistance biology and provide guidance for breeding practices in this promising crop species and other cereals.
The Pacific oyster Crassostrea gigas belongs to one of the most species-rich but genomically poorly explored phyla, the Mollusca. Here we report the sequencing and assembly of the oyster genome using ...short reads and a fosmid-pooling strategy, along with transcriptomes of development and stress response and the proteome of the shell. The oyster genome is highly polymorphic and rich in repetitive sequences, with some transposable elements still actively shaping variation. Transcriptome studies reveal an extensive set of genes responding to environmental stress. The expansion of genes coding for heat shock protein 70 and inhibitors of apoptosis is probably central to the oyster's adaptation to sessile life in the highly stressful intertidal zone. Our analyses also show that shell formation in molluscs is more complex than currently understood and involves extensive participation of cells and their exosomes. The oyster genome sequence fills a void in our understanding of the Lophotrochozoa.
This experiment explored the effects of single application of seven types of slow- and controlled-release fertilizers on rice yield and various population characteristics. Based on a study of the ...nitrogen (N) release characteristics of these fertilizers, pot experiments were conducted in 2018 and 2019 with split fertilization (CK, urea applied split equally at basal and panicle initiation stages, respectively) as control, which assessed the effects on SPAD value, yield and yield components, dynamic changes of rice tillers and dry matter accumulation. The results showed that the N release characteristics of different types of slow- and controlled-release fertilizers were significantly different. Polymer-coated urea (PCU) showed a controlled-release mode and provided sustained release throughout the whole growth stages. Sulfur-coated urea (SCU) exhibited a slow-release mode, providing insufficient release at the middle and late stages. Urease inhibitor urea (AHA) and urea-formaldehyde (UF) yielded a rapid-release mode, with an explosive N release at the early stage and no release at the middle and late stages. These results showed that PCU delayed the peak seedling stage. Compared with CK, dry matter accumulation and SPAD showed no significant differences, and due to the continuous release of N throughout the growth stages, rice yield, spikelets per panicle, seed setting rate, and 1 000-grain weight were all increased. Owing to the lack of N supply at the late stage and the low number of spikelets, SCU led to a reduction of rice yield, which is nevertheless not statistically significant. AHA and UF were susceptible to environmental factors and had varying effects on rice yield. The results of this experiment indicated that given a fixed amount of N applied in a pot, the stronger the N supply capacity and the longer the effective duration time of the fertilizer, the higher the dry matter accumulation at the late growth stage, and the higher the rice yield.
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