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Single-cross maize hybrids display superior heterosis and are produced from crossing two parental inbred lines belonging to genetically different heterotic groups. Here we assembled 1,604 historically utilized maize inbred lines belonging to various female heterotic groups (FHGs) and male heterotic groups (MHGs), and conducted phenotyping and genomic sequencing analyses. We found that the FHGs and MHGs have undergone both convergent and divergent changes for different sets of agronomic traits. Using genome-wide selection scans and association analyses, we identified a large number of candidate genes that contributed to the improvement of agronomic traits of the FHGs and MHGs. Moreover, we observed increased genetic differentiation between the FHGs and MHGs across the breeding eras, and we found a positive correlation between increasing heterozygosity levels in the differentiated genes and heterosis in hybrids. Furthermore, we validated the function of two selected genes and a differentiated gene. This study provides insights into the genomic basis of modern hybrid maize breeding.

In Li and Ren (Int. J. Numer. Methods Fluids 70: 742–763, 2012), a high-order k-exact WENO finite volume scheme based on secondary reconstructions was proposed to solve the two-dimensional time-dependent Euler equations in a polygonal domain, in which the high-order numerical accuracy and the oscillations-free property can be achieved. In this paper, the method is extended to solve steady state problems imposed in a curved physical domain. The numerical framework consists of a Newton type finite volume method to linearize the nonlinear governing equations, and a geometrical multigrid method to solve the derived linear system. To achieve high-order non-oscillatory numerical solutions, the classical k-exact reconstruction with $$k=3$$ and the efficient secondary reconstructions are used to perform the WENO reconstruction for the conservative variables. The non-uniform rational B-splines (NURBS) curve is used to provide an exact or a high-order representation of the curved wall boundary. Furthermore, an enlarged reconstruction patch is constructed for every element of mesh to significantly improve the convergence to steady state. A variety of numerical examples are presented to show the effectiveness and robustness of the proposed method.

Fetal growth restriction (FGR) ranks second among causes of perinatal death. Circular RNA hsa_circ_0074371 (hsa_circ_0074371) is reported to be downregulated in FGR placentae. However, the role and regulatory mechanism of hsa_circ_0074371 in FGR pathogenesis are indistinct. Expression of hsa_circ_0074371, microRNA (miR)-582-3p, and low-density lipoprotein receptor-related protein 6 (LRP6) mRNA in FGR placentae and trophoblast cells (HTR-8/SVneo) was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The relationship between hsa_circ_0074371 or LRP6 and miR-582-3p was verified by dual-luciferase reporter and/or RNA immunoprecipitation (RIP), RNA pull-down assays. The proliferation, cell cycle progression, apoptosis, migration, and invasion of HTR-8/SVneo cells were evaluated by Cell Counting Kit-8 (CCK-8), flow cytometry, wound healing, or transwell assays. Caspase3 activity was analyzed with a commercial kit. The protein levels of c-myc, cyclinD1, matrix metalloproteinase (MMP) 2, MMP9, and LRP6 were examined by western blotting. We observed that hsa_circ_0074371 and LRP6 were downregulated while miR-582-3p was upregulated in FGR placentae and HTR-8/SVneo cells. Hsa_circ_0074371 modulated LRP6 expression via sponging miR-582-3p. Hsa_circ_0074371 knockdown induced cell cycle arrest, apoptosis, and inhibited cell proliferation, migration, and invasion in HTR-8/SVneo cells. MiR-582-3p inhibitor reversed hsa_circ_0074371 silencing me on proliferation, migration, and invasion of HTR-8/SVneo cells. LRP6 overexpression overturned the inhibitory effect of miR-582-3p mimic on proliferation, migration, and invasion of HTR-8/SVneo cells. In conclusion, hsa_circ_0074371 downregulation inhibited proliferation, migration, and invasion of trophoblast cells via sponging miR-582-3p and decreasing LRP6 expression, providing a new mechanism related to FGR pathogenesis.

Background The Northeast Plain of China, which is an important region for the production of high grain quality rice in China. However, the grain quality of the rice produced varies across this region, even for the same cultivar. Objective In order to explore the meteorological factors that have the greatest influence on quality and the transcriptional level differences between different cultivars and different locations at grain filling stage. Methods We grew eight rice cultivars in three locations in Northeast China during two growing seasons (2017 and 2018). We recorded meteorological conditions, including air temperature, air temperature range, and photosynthetically active radiation (PAR) during the grain-filling stage of each cultivar, and analyzed the grain quality of those eight cultivars. Results Across all eight cultivars, meteorological factors had a stronger effect on eating quality than genotype, while genotype had a stronger effect on milling quality. Of the three environmental factors assessed, PAR was significantly correlated with the most grain quality traits. Using RNA-sequencing analysis, we identified 573 environment-specific DEGs (Differentially Expressed Genes), and 119 genotype-specific DEGs; 11 DEGs were responsive to genotype × environment interactions. These DEGs were involved in many key metabolic processes. Conclusion Our results indicated that interactions among environmental factors, especially PAR, affected rice quality in Northeast China. Further analyses of the DEGs identified herein may provide useful information for future breeding programs aiming to develop high grain quality rice varieties suitable for cultivation across Northeast China.

Ephemeral gullies, which are widely developed worldwide and threaten farmlands, have aroused a growing concern. Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment. However, ephemeral gully mapping remains a challenge. In this study, we proposed a flow-directional detection for identifying ephemeral gullies from high-resolution images and digital elevation models (DEMs). Ephemeral gullies exhibit clear linear features in high-resolution images. An edge detection operator was initially used to identify linear features from high-resolution images. Then, according to gully erosion mechanism, the flow-directional detection was designed. Edge images obtained from edge detection and flow directions obtained from DEMs were used to implement the flow-directional detection that detects ephemeral gullies along the flow direction. Results from ten study areas in the Loess Plateau of China showed that ranges of precision, recall, and F-measure are 60.66%–90.47%, 65.74%–94.98%, and 63.10%–91.93%, respectively. The proposed method is flexible and can be used with various images and DEMs. However, analysis of the effect of DEM resolution and accuracy showed that DEM resolution only demonstrates a minor effect on the detection results. Conversely, DEM accuracy influences the detection result and is more important than the DEM resolution. The worse the vertical accuracy of DEM, the lower the performance of the flow-directional detection will be. This work is beneficial to research related to monitoring gully erosion and assessing soil loss.

Salt stress is a devastating environmental stress that causes plant growth inhibition and yield reduction. The identification of salt-tolerant genes brings hope for the generation of salinity-tolerant crop plants through molecular breeding. In this study, one salt-sensitive and one salt-tolerant maize inbred line were screened from 242 maize inbred lines. Reactive oxygen species (ROS)-related enzyme activities were detected and salt-responsive comparative transcriptome analysis was performed for control and 220 mM NaCl treated maize leaves. Salt-tolerant maize inbred line (L87) showed higher ROS-related enzyme (SOD, POD, APX and CAT) activities and accumulated relatively lower levels of ROS under salt stress. Of the total DEGs, 1856 upregulated DEGs were specific to L87, including stress tolerance-related members of the 70kDa family of heat shock proteins (Hsp70s) and aquaporins. The DEGs involved in the abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid (SA) signal transduction pathways may determine the difference in salt tolerance between the two varieties, especially one central component SnRK2, that positively regulates ABA signaling and was only upregulated in L87. Analysis of DEGs related to ROS scavenging showed that some peroxidase (POD), glutathione S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) genes specific to L87 probably enhanced its salt tolerance. The analysis of differentially expressed transcription factors (TFs) suggested that WRKY TFs could contribute to the difference in salt tolerance between the two maize lines. Compared with Salt-sensitive maize inbred line (L29), L87 exhibits specific regulatory mechanisms related to salt tolerance, including plant hormone interactions, ROS scavenging and the regulation of TFs. Our study identifies new candidate genes that may regulate maize tolerance to salt stress and provides useful information for breeding maize with high salt resistance.

Nanostructured Cu oxides hold great promise as electrode materials for supercapacitors due to their low cost, high theoretical capacitance (1800 F g−1), as well as superior environmental benignity. In this work, hybrid three-dimensional (3D) network and flower-like structure CuO nanoparticles in situ grow on a 3D submicron-porous/solid copper current collector (S/SPCu) via a simple hydrothermal method using H2O2. Benefited from this unique hybrid porous architecture, the as-prepared CuO/S/SPCu electrode shows a high specific capacitance of 445 F g−1 at 2 mA cm−2, high rate capability (60.7% at 64 mA cm−2) and good cycling stability (82.8% capacitance retention after 2000 cycles). The high performance hybrid structure makes the environment-friendly and low-cost CuO/S/SPCu electrode a promising electrode material for supercapacitor applications.

High order methods play important roles in the modelling of compressible multi-component flows. However, they may generate negative sound speed, which leads to an instability of the numerical schemes. In this paper, we propose bound- and positivity-preserving limiters for high order finite difference schemes, based on which the equilibriums of the velocity and pressure are preserved throughout the whole computation of contact moving interface problems with the ideal and stiffened equations of state. For illustration purpose, high order alternative WENO scheme is taken for example. Numerical examples verify the theory and demonstrate the robustness of the proposed bound- and positivity-preserving limiters.

We establish a logarithmic stability estimate for the inverse problem of determining the nonlinear term, appearing in a semilinear boundary value problem, from the corresponding Dirichlet-to-Neumann map. Our result can be seen as a stability inequality for an earlier uniqueness result by Isakov and Sylvester (Commun Pure Appl Math 47:1403–1410, 1994).

A hybrid titanium chromium nitride nanotube (Ti0.95Cr0.05N NT) support was prepared by a facile synthesis procedure and further used as support for Pt nanoparticles (Pt/Ti0.95Cr0.05N NTs). The catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen absorption/desorption, which show that the Pt/Ti0.95Cr0.05N NTs are formed with homogeneous cohesively attached nitride nanotube crystals. The X-ray photoelectron spectroscopy (XPS) reveals that the interaction between Ti0.95Cr0.05N NTs and Pt nanoparticles is enhanced due to the Cr element doping. Furthermore, the electrochemical experiments demonstrate that Ti0.95Cr0.05N NT-supported Pt catalyst exhibits enhanced catalytic activity and durability for methanol electrooxidation compared with traditional Pt/C catalyst. The experimental dates indicate that the excellent stability and durability of Pt/Ti0.95Cr0.05N NTs toward methanol electrochemical oxidation might be mainly ascribed to the synergistic effect introduced by Cr doping and the tubular nanostructures. The above results indicate that Ti0.95Cr0.05N NTs as support have a promising future in direct methanol fuel cells.

In Radovitzky and Ortiz (Comput Methods Appl Mech Eng 172(1–4):203–240, 1999), an error estimation technique for nonlinear PDEs is presented to adaptively generating mesh, based on the reduction of the order of the approximate polynomial. In this paper, following a similar analysis framework, we propose an a posteriori error estimation for Kohn–Sham equation by coarsening mesh. An upper bound for the difference of the total energies on two successively refined meshes is derived by the numerical solutions on two meshes through an asymptotic analysis, which finally generates an a posteriori error estimation. A variety of numerical tests show that such an a posteriori error estimation works very well in our h-adaptive finite element method framework. In addition, to further improve the efficiency, we solve a Poisson equation instead of the Kohn–Sham equation on the coarsened mesh. The effectiveness of this improvement is analyzed and numerically examined.

A titanium silicon nitride nanotubes (Ti0.95Si0.05N NTs) support with a one-dimensional (1D) nanostructure is controllable prepared in a controlled manner by adjusting the molar ratio of the precursors, and the Ti0.95Si0.05N NTs support is further decorated with Pt nanoparticles to form an electrocatalyst for methanol electrooxidation. Transmission electron microscopy shows that the Ti0.95Si0.05N NTs are formed with nanocrystals, and the hollow structure is composed of mesoporous walls. The N2 adsorption–desorption results reveal that the novel 1D nanotube structure exhibits a large Brunauer–Emmett–Teller surface area, and the XPS patterns demonstrate the strong interaction between the Ti0.95Si0.05N NTs support and the Pt nanoparticles. Furthermore, the electrochemical measurements show that the Pt/Ti0.95Si0.05N NTs exhibit an enhanced performance and stability compared to the conventional Pt/C catalysts. The dramatically improved durability of the catalyst is confirmed by the accelerated durability test. The combination of facile preparation and remarkable electrochemical performance demonstrates that Ti0.95Si0.05N NTs are promising candidates as supports for direct methanol fuel cells.

In the present study, Pt nanoparticles (20 wt%) were successfully anchored on vanadium (V)-doped titanium nitride hybrid support, which controllable prepared by adjusting the ratio of precursors. Electrochemical performance of the novel Pt/Ti0.8V0.2N electrocatalyst exhibits well stability and better electrocatalytic activity than the conventional Pt/C electrocatalyst under direct methanol fuel cells (DMFCs) conditions. Notable, Pt/Ti0.8V0.2N exhibits negative onset potential (ca. 0.1 V) and higher current density than Pt/TiN (1.7-fold) and Pt/C (2.5-fold), clearly demonstrating that methanol can be oxidized more easily on Pt/Ti0.8V0.2N catalyst. These results indicate that the V doping has co-catalytic and electronic effects, and the hybrid material is indeed a promising support to improve Pt catalytic activity and durability for practical DMFCs.

A simple and fast method is described for the extraction of polycyclic aromatic hydrocarbons (PAHs) from complex samples. It is based on the use of a nanoferrofluid modified with a ternary hydrophobic deep eutectic solvent. A predictive model was used for the selection of the optimal eutectic mixture. The entire microextraction only takes a few minutes for completion. Under the optimal extraction conditions (by using menthol, borneol and camphor in a molar ratio of 5:1:4; 80 mg of nanoferrofluid), it offers marked improvements in terms of selectivity and sensitivity. The limits of detection range between 0.31 and 5.9 ng·L−1, and recoveries from spiked samples between 91.3 and 121%. In addition, the strong interactions between PAHs and the extractant were supported by quantum mechanical calculations. This results in a better insight into the microextraction mechanism, providing a fast, environmentally friendly and effective route for the optimization of pretreatment parameters. The method was successfully applied to the determination of the PAHs naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene and indeno[1,2,3-c,d]pyrene in 12 kinds of coffee samples after different roasting conditions.

Background It is an established fact that excess of glucocorticoids could cause the harmful effects, such as suppression on the male reproduction. Although glucocorticoids pharmacologically inhibit the Leydig cell function, their roles in Leydig cell development are unclear. Therefore, the present study was designed to investigate effects of synthetic glucocorticoid dexamethasone (DEX) on rat stem Leydig cell proliferation and differentiation. Methods Male Sprague-Dawley rats received a single intraperitoneal injection of 75 mg/kg EDS to eliminate Leydig cells and an in vitro culture system of the seminiferous tubules was established from Leydig cell-depleted testis. Using basal medium and Leydig cell differentiation-inducing medium (LIM) in the culture system, we examined the effects of DEX (0–100 nM) on the proliferation and differentiation of the stem Leydig cells in vitro, respectively. Results Results showed that LIM is a good agent to induce stem Leydig cell differentiation into Leydig cells that produce testosterone in vitro. DEX inhibited the differentiation of stem Leydig cells by reducing the expression levels of Cyp17a1 and Scarb1 and that NR3C1 antagonist RU38486 reversed the DEX-mediated effects. However, DEX are not involved with the proliferation of stem Leydig cells. Conclusions DEX suppressed the differentiation of rat Leydig cells in vitro and glucocorticoid-induced effects acted through NR3C1. This suppression partially targets on Cyp17a1 and Scarb1 gene expression.

In this work, the TiO2 tubes (TBs) were prepared by solvothermal method. The morphology and phase structure of TiO2 TBs is significantly affected by N2 annealing temperature. XRD was used to characterize the phase structure of the as-prepared samples. The morphology and surface areas were characterized by SEM and N2 adsorption–desorption, which show that the tubes were assembled with about 100-nm nanosheets and small ball particles under 400 and 600 °C N2 annealing; when temperature reached 800 °C, the surface of tubes appeared a lot of collapse and many large holes. In addition, the surface areas of 400 °C TiO2, 600 °C TiO2, and 800 °C TiO2 TBs were significantly affected by N2 annealing. Most importantly, the UV-vis and electrochemical tests demonstrate 600 °C TiO2 TBs exhibit higher absorption intensity and photocurrent; thus, it possess on better photocatalytic activity. Therefore, the photocatalytic performance for TiO2 TBs is significantly co-affected by surface area and mix-phase.

Nitrogen and sulfur co-doped graphene quantum dots (NS-GQDs) were successfully synthesized using a facile, inexpensive, and environmentally friendly hydrothermal reaction of aqueous ammonia, S powder, and graphene quantum dots. The NS-GQDs with oxygen-rich functional groups have a high quantum yield of 41% and a diameter of 1–5 nm. The photoluminescence (PL) properties of the nitrogen-doped graphene quantum dots (N-GQDs) and NS-GQD were investigated. The results showed that the PL emission of the NS-GQD exhibits a clear blue shift of 54 nm compared to that of the N-GQDs.

Maize (Zea mays, L.) cultivation has expanded greatly from tropical to temperate zones; however, its sensitivity to chilling often results in decreased germination rates, weak seedlings with reduced survival rates, and eventually lower yields. We conducted germination tests on the maize-282-diverse-panel (282 inbred lines) under normal (25 °C) and chilling (8 °C) conditions. Three raw measurements of germination were recorded under each condition: 1) germination rate, 2) days to 50% germination, and 3) germination index. Three relative traits were derived as indicators of cold-tolerance. By using the 2,271,584 single nucleotide polymorphisms (SNPs) on the panel from previous studies, and genome-wide association studies by using FarmCPU R package to identify 17 genetic loci associated with cold tolerance. Seven associated SNPs hit directly on candidate genes; four SNPs were in high linkage disequilibrium with candidate genes within 366 kb. In total, 18 candidate genes were identified, including 10 candidate genes supported by previous QTL studies and five genes supported by previous gene cloning studies in maize, rice, and Arabidopsis. Three new candidate genes revealed by two associated SNPs were supported by both QTL analyses and gene cloning studies. These candidate genes and associated SNPs provide valuable resources for future studies to develop cold-tolerant maize varieties.

Background Soybean (Glycine max [L.] Merr.) is one of the most important oil and protein crops. Ever-increasing soybean consumption necessitates the improvement of varieties for more efficient production. However, both correlations among different traits and genetic interactions among genes that affect a single trait pose a challenge to soybean breeding. Results To understand the genetic networks underlying phenotypic correlations, we collected 809 soybean accessions worldwide and phenotyped them for two years at three locations for 84 agronomic traits. Genome-wide association studies identified 245 significant genetic loci, among which 95 genetically interacted with other loci. We determined that 14 oil synthesis-related genes are responsible for fatty acid accumulation in soybean and function in line with an additive model. Network analyses demonstrated that 51 traits could be linked through the linkage disequilibrium of 115 associated loci and these links reflect phenotypic correlations. We revealed that 23 loci, including the known Dt1, E2, E1, Ln, Dt2, Fan, and Fap loci, as well as 16 undefined associated loci, have pleiotropic effects on different traits. Conclusions This study provides insights into the genetic correlation among complex traits and will facilitate future soybean functional studies and breeding through molecular design. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1289-9) contains supplementary material, which is available to authorized users.

A mesh redistribution method is introduced to solve the Kohn-Sham equation. The standard linear finite element space is employed for the spatial discretization, and the self-consistent field iteration scheme is adopted for the derived nonlinear generalized eigenvalue problem. A mesh redistribution technique is used to optimize the distribution of the mesh grids according to wavefunctions obtained from the self-consistent iterations. After the mesh redistribution, important regions in the domain such as the vicinity of the nucleus, as well as the bonding between the atoms, may be resolved more effectively. Consequently, more accurate numerical results are obtained without increasing the number of mesh grids. Numerical experiments confirm the effectiveness and reliability of our method for a wide range of problems. The accuracy and efficiency of the method are also illustrated through examples.

Recent advances in genomics, metabolomics and proteomics have made it possible to interrogate disease pathophysiology and drug response on a systems level. The analysis and interpretation of the complex data obtained using these techniques is potentially fertile but equally challenging. We conducted a small clinical trial to explore the application of metabolomics data in candidate biomarker discovery. Specifically, serum and urine samples from patients with type 2 diabetes mellitus (T2DM) were profiled on metabolomics platforms before and after 8 weeks of treatment with one of three commonly used oral antidiabetic agents, the sulfonyurea glyburide, the biguanide metformin, or the thiazolidinedione rosiglitazone. Multivariate classification techniques were used to detect serum or urine analytes, obtained at baseline (pre-treatment) that could predict a significant treatment response after 8 weeks. Using this approach, we identified three analytes, measured at baseline, that were associated with response to a thiazolidinedione after 8 weeks of treatment. Although larger and longer-term studies are required to validate any of the candidate biomarkers, pharmacometabolomic profiling, in combination with multivariate classification, is worthy of further exploration as an adjunct to clinical decision making regarding treatment selection and for patient stratification within clinical trials.

Direct electroless nickel plating onn-Si(100) wafers in alkaline solutions was demonstrated without any activation procedure in advance, the effect of pH and temperature of the solutions on size of metal particles in deposits was examined, and also the element contents of deposits were analyzed by energy disperse spectroscopy (EDS). The results indicated that the size of metal particles increases with increasing temperature or decreasing pH. The possible mechanism of nickel deposition onn-Si(100) was discussed in terms of semiconductor electrochemistry, and the formation of nickel seed crystal on Si was mainly attributed to the generation of atomic hydrogen by electron capture of water molecule from the semiconductor in alkaline solutions.