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In order to determine the ecological risk and health risk of Arsenic (As) and Cadmium (Cd) in soils from a typical mining city in Huainan, a total of 99 soil samples were collected and analyzed. The results showed that the concentrations of As and Cd ranged from 3.2 to 39.50 and 0.01 to 0.19 mg/kg, respectively, which exceeded the soil background values by 6.06 and 14.14%, respectively. The soil pH and content of organic carbon demonstrated no significant (P > 0.05) correlation with the As and Cd concentrations, while the land use types significantly (P

The reliable design and prediction of enzyme promiscuity to access transformations not observed in nature remains a long-standing challenge. Herein, we present the first example of an intramolecular stereoselective Stetter reaction catalyzed by benzaldehyde lyase, guided by the rational structure screening of various ThDP-dependent enzymes using molecular dynamics (MD) simulations. After optimization, high productivity (up to 99 %) and stereoselectivity (up to 99:1 e.r.) for this novel enzyme function was achieved.

Lysine 2-hydroxyisobutyrylation (Khib ) is a newly identified post-translational modification (PTM) that plays important roles in transcription and cell proliferation in eukaryotes. However, its function remains unknown in phytopathogenic fungi. Here, we performed a comprehensive assessment of Khib in the rice false smut fungus Ustilaginoidea virens, using Tandem Mass Tag (TMT)-based quantitative proteomics approach. A total of 3 426 Khib sites were identified in 977 proteins, suggesting that Khib is a common and complex PTM in U. virens. Our data demonstrated that the 2-hydroxyisobutyrylated proteins are involved in diverse biological processes. Network analysis of the modified proteins revealed a highly interconnected protein network that included many well-studied virulence factors. We confirmed that the Zn-binding reduced potassium dependency3-type histone deacetylase (UvRpd3) is a major enzyme that removes 2-hydroxyisobutyrylation and acetylation in U. virens. Notably, mutations of Khib sites in the mitogen-activated protein kinase (MAPK) UvSlt2 significantly reduced fungal virulence and decreased the enzymatic activity of UvSlt2. Molecular dynamics simulations demonstrated that 2-hydroxyisobutyrylation in UvSlt2 increased the hydrophobic solvent-accessible surface area and thereby affected binding between the UvSlt2 enzyme and its substrates. Our findings thus establish Khib as a major post-translational modification in U. virens and point to an important role for Khib in the virulence of this phytopathogenic fungus.

Artificial induction of polyploidy is widely used in breeding programmes to improve the agronomic traits. The drumstick tree (Moringa oleifera Lam.) has a range of potential commercial uses, as the vegetative organs have high nutritional, medicinal, and feed values. In the present study, in vitro tetraploidisation in drumstick tree was performed by treating leaf segments with colchicine and subsequently verifying the ploidy levels. For polyploidisation, explant survival and regeneration rates were affected more by exposure time than by colchicine concentration, and the highest polyploidisation efficiency was observed at 500 mg/L colchicine for 3 days, which yielded 21% tetraploids. The morphological characteristics and contents of seven fodder-related nutrients (crude protein, ether extract, ash, acid detergent fibre, neutral detergent fibre, calcium, and phosphorus) in the leaves and shoots were compared between tetraploid and diploid drumstick trees. The resulting tetraploids showed significantly enhanced leaf and stomatal size. In addition, the contents of seven fodder-related nutrients were higher, although to varying degrees, in tetraploids than in diploids. The results indicated that the tetraploid produced in this study exhibited superior agronomical traits and improved biomass yield than diploids, and may represent excellent raw materials for fodder to enhance biomass and nutrition.

We used the cotyledons and cotyledonary nodes of Toona ciliata (Chinese mahogany) as explants to examine callus and adventitious shoot induction when exposed to different ratios of hormones. We also investigated the effects of seedling age, inoculation method, and genotype on the efficient regeneration of T. ciliata. The results showed that different genotypes exhibited significantly different callus induction efficiency. The cotyledons and cotyledonary nodes of 20-day seedlings inoculated onto MS medium with 0.5 mg/L 6-benzylaminopurine (6-BA), 0.5 mg/L kinetin (KT) and 0.05 mg/L 1-naphthylacetic acid (NAA) achieved a greater regeneration rate than did other concentrations of cytokinin and auxin. The numbers of shoots per cotyledon and cotyledonary node explant were 7.33 and 6.67. The optimal inoculation method for cotyledons was that the distal end of the explants was placed in contact with the medium. The optimal adventitious shoot differentiation medium for cotyledon explants was MS medium containing 0.3 mg/L 6-BA and 0.2 mg/L NAA, producing a 3.4 cm height of shoot on average. This study established an efficient regeneration system for T. ciliata with cotyledons and cotyledonary nodes as explants.

The floral transition of the maize (Zea mays ssp. mays) shoot apical meristem determines leaf number and flowering time, which are key traits influencing local adaptation and yield potential. dlf1 (delayed flowering1) encodes a basic leucine zipper protein that interacts with the florigen ZCN8 to mediate floral induction in the shoot apex. However, the mechanism of how dlf1 promotes floral transition remains largely unknown. We demonstrate that dlf1 underlies qLB7-1, a quantitative trait locus controlling leaf number and flowering time that was identified in a BC2 S3 population derived from a cross between maize and its wild ancestor, teosinte (Zea mays ssp. parviglumis). Transcriptome sequencing and chromatin immunoprecipitation sequencing demonstrated that DLF1 binds the core promoter of two AP1/FUL subfamily MADS-box genes, ZmMADS4 and ZmMADS67, to activate their expression. Knocking out ZmMADS4 and ZmMADS67 both increased leaf number and delayed flowering, indicating that they promote the floral transition. Nucleotide diversity analysis revealed that dlf1 and ZmMADS67 were targeted by selection, suggesting that they may have played important roles in maize flowering time adaptation. We show that dlf1 promotes maize floral transition by directly activating ZmMADS4 and ZmMADS67 in the shoot apex, providing novel insights into the mechanism of maize floral transition.

The surface topology of biomaterial has a definite effect on the growth behavior of nerve cells for peripheral nerve regeneration. In this study, the silk fibroin (SF) film with different anisotropic microgroove/ridge was constructed by micropatterning technology. The effects of topologies width on the directional growth of dorsal root ganglion (DRG) neurons were evaluated. The results showed that the topological structure of the SF film with higher SF concentration was more clear and complete. The microtopography of the SF film with a concentration of 15% and a groove width of around 30 μm could effectively guide the directional growth of the nerve fibers of DRG. And nerve fibers could obviously form nerve fiber bundles which may have a certain pavement effect on the recovery of nerve function. The study indicated that the SF film with a specific width of the topological structure may have potential applications in the field of directional nerve regeneration.

One of the key tasks in solid oxide fuel cell research is to develop cost-competitive electrodes that work efficiently in wide range of air and fuel utilizations. Herein, we promote our study to a series of Cobalt and Titanium substituted La0.4Sr0.6Fe0.7Ti0.3-xCoxO3-δ (LSFTC, x = 0, 0.05, 0.1, 0.2) perovskite oxides. It is shown that Cobalt doping effectively improves the electrical conductivity and oxygen electrochemical reduction activity, yielding decreased cathode polarization resistance and lower dependence of p O 2 change. For example, σ 600 °C = 81 S/cm and R p , C 750 °C = 0.1 Ω cm2 for LSFTC-5 are obtained in p O 2 = 0.21 a t m . In anode conditions of wet H2, the LSFTC cubic perovskites are partially reduced to hybrid structure of ABO3-A2BO4-metal with Cobalt doping amount less than 10% and are fully decomposed to A2BO4-metal with 20% doping. The higher Cobalt substitution generates more nano particles exsolution, which promotes anode processes at low temperatures. However, the generated AO-rich compositions are shown detrimental to anode performance in both conducting property and anode catalytic activity under low H2 partial pressures. In current study, the electrodes are evaluated under practical working conditions with broad p O 2 and p H 2 , which provides guidelines for industrial-applicable SrFeO3 based symmetrical electrode development.

Paper mulberry (Broussonetia papyrifera) is a tree species that has many economic, ecological, and social uses. This study developed an efficient protocol for regenerating shoots from leaf explants using Murashige and Skoog (MS) medium supplemented with different concentrations of plant growth regulators (PGRs), which play vital roles in shoot regeneration. The best result, 86.67% induction frequency and 4.35 shoots per explant, was obtained in the MS medium containing 2.0 mg/L N6-benzyladenine (BA) and 0.05 mg/L indole-3-butyric acid. The effects of explant age, orientation, and genotype were also investigated. Explants from young leaves had a greater regeneration frequency than those from old leaves, and the results were better when the distal end of the leaf explant contacted the medium versus the proximal end. Approximately 70.96% of the shoots rooted well in the MS medium containing 0.4 mg/L α-naphthalene acetic acid (NAA). Although some genotypes achieved poorer results, the regeneration protocol is still applicable for mass multiplication and genetic transformation.

In this work, we demonstrated that titanium silicalite-1 (TS-1) crystal planes affected the activity of nanogold supported on TS-1 (denoted as Au/TS-1) for direct propylene epoxidation with H2 and ...

The radio frequency magnetron sputtering technology (RFMS) was employed to deposit perovskite structure orthogonal phase CaZrO3 thin films on Pt/Ti/SiO2/Si substrates. The effects of substrate temperatures on structure and electrical properties of these films were investigated in detail. The CaZrO3 thin films were systematically characterized by means of X-ray diffraction (XRD), Scanning electron microscope (SEM), Multi-frequency LCR meter (HP4294A) and Radiant Precision Workstation to study the phase structure, cross-section morphology, dielectric and ferroelectric properties at different substrate temperatures. The result indicates that these films can withstand 80 V DC Bias voltage and have excellent stability of frequency, voltage and temperature. The CaZrO3 thin film prepared at 550 °C turned out to be mainly orthorhombic CaZrO3 phase with high permittivity, low dielectric loss, extremely low leakage current (at 1 MHz, the dielectric constant is 39.42, the dielectric loss is 0.00455, the quality factor is 220 and the leakage current density is 9.11 × 10−7A/cm2 at 80 V applied voltage.). This work demonstrates that higher substrate temperature can boost the formation of orthorhombic CaZrO3 phase and the CaZrO3 thin film prepared by RF magnetron sputtering is a very promising paraelectric material in the application of thin film capacitor.

We present the optical and infrared properties of 39 extremely radio-loud galaxies discovered by cross-matching the Subaru/Hyper Suprime-Cam (HSC) deep optical imaging survey and VLA/FIRST 1.4 GHz radio survey. The recent Subaru/HSC strategic survey revealed optically-faint radio galaxies (RG) down to $g_\mathrm{AB} \sim 26$, opening a new parameter space of extremely radio-loud galaxies (ERGs) with radio-loudness parameter of $\log \mathcal{R}_\mathrm{rest} = \log (f_{1.4 \mathrm{GHz,rest}}/f_{g,\mathrm{rest}}) >4$. Because of their optical faintness and small number density of $\sim1~$deg$^{-2}$, such ERGs were difficult to find in the previous wide but shallow, or deep but small area optical surveys. ERGs show intriguing properties that are different from the conventional RGs: (1) most ERGs reside above or on the star-forming main-sequence, and some of them might be low-mass galaxies with $\log (M_\star/M_\odot) < 10$. (2) ERGs exhibit a high specific black hole accretion rate, reaching the order of the Eddington limit. The intrinsic radio-loudness ($\mathcal{R}_\mathrm{int}$), defined by the ratio of jet power over bolometric radiation luminosity, is one order of magnitude higher than that of radio quasars. This suggests that ERGs harbor a unique type of active galactic nuclei (AGN) that show both powerful radiations and jets. Therefore, ERGs are prominent candidates of very rapidly growing black holes reaching Eddington-limited accretion just before the onset of intensive AGN feedback., 20 pages, 10 figures, accepted for publication in ApJ

The in-situ precipitated nano metal particle-perovskite anodes show promising application prospects in Solid Oxide Fuel Cells. Previously reports mainly show new exsolved material, but barely focus on their practical application concerns. Herein, the structural and electrochemical properties evolution of (La0.4Sr0.6)1-xCo0.2Fe0.7Nb0.1O3-δ (LSCFN, x = 0, 0.05, 0.1) versus varied anode fuel atmospheres are presented. Results show that perovskite-type LSCFN anodes are fully reduced to K2NiF4 structure in dry H2 at 850 °C, but maintain to be ABO3 structure with minor structure change under water containing H2. The exsolved Co1-xFex phases are observed under both conditions, but with much higher Fe content under dry H2. The Electrochemical Impedance Spectra shows that LSCFN anodes are more sensitive to p H 2 change under humidified fuels than dry conditions. Single cells with (La0.4Sr0.6)0.9Co0.2Fe0.7Nb0.1O3-δ anode show promising performance with maximum power densities of 1.2 and 0.95 W/cm2 under dry and wet H2 at 850 °C, respectively.

Polycyclic aromatic hydrocarbons (PAHs), a family of persistent organic pollutants with various negative health effects, are inherently formed during biochar pyrolysis. However, the knowledge regarding the leaching potentials and mechanisms of PAHs remains limited for biochar implementation to soil. In this study we evaluated the leaching behaviors of PAHs from sewage sludge-derived biochar pyrolyzed at different temperatures (300–700 °C) using the protocol of Synthetic Precipitation Leaching Procedure (SPLP) with deionized water. Leachate concentrations of sixteen U.S. Environmental Protection Agency PAHs increased with the increasing pyrolysis temperature, exhibiting an opposite pyrolytic temperature dependence with their concentrations in biochar. The total leachate PAH concentration peaked at 700 °C with 11.75 μg/L, corresponding to 15.9% of total PAHs present in biochar. PAH leaching was associated with the release of hydrophobic organic compounds (HOCs) that created a mobile phase to facilitate the mobilization of PAHs into water. The enhanced release of calcium, aluminum, and barium from the biochars with pyrolysis temperature could also favor the leaching of biochar PAHs, due to the destruction of HOCs-(metal ions)-mineral linkages, which improved the release of HOCs and HOCs-bound PAHs; and because the extent of metal cross-linking in biochar is reduced, enabling better diffusion of PAHs through the inner matrix and thus accelerating their desorption.

Neolamarckia cadamba is an important fast growing tree species used for pulping and wood material in industry for it’s desirable wood properties. As one of the most important content in wood, lignin provides structural integrity, strength, and hydrophobicity to the thickened cell walls and is the major factor contributing to biomass recalcitrance. It does not reduce the palatability of forage grass for animals, but it hinders the isolation of cellulose fibers and the efficient enzymatic depolymerization of cellulose and hemicellulose into fermentable sugars in biorefining processes by limiting the access by hydrolytic enzymes to their polysaccharide substrates. This work focused on analyzing the functions of NcCSE (Caffeoyl Shikimate Esterase, GenBank accession number: MG739672) and NcHCT (Hydroxycinnamoyl Transferase,GenBank accession number: MG739673) in the lignin biosynthetic process in order to improve the potential for utilization of leaves and wood from N. cadamba. The mutant phenotype of cse-2 was dramatically complemented to WT in the stable transgenic lines cse-35S::NcCSE, but overexpression of NcHCT in the cse-2 mutant did not have the same result as cse-35S::NcCSE, providing only partial complementation.

This work reports the structure, growth rate, dielectric response, and capacitance properties of (100)-oriented Ba0.67Sr0.33TiO3 (BST)/LaNiO3 (LNO) hetero-structure thin films with varied BST layer thicknesses from 34 nm to 342 nm. The BST/LNO hetero-structure thin films were prepared by radiofrequency magnetron sputtering technique on Pt/SiO2/Si substrates. The XRD results showed that the compressive stress is relaxed at around 73 nm of BST layer, and above 119 nm of the BST layer thickness, the tensile stress has a significant effect on the crystal structure of the BST/LNO hetero-structure film. The growth rate of the BST films was thickness-dependent which was strongly related to the minimization of the strain energy. The dielectric constant of BST layer with the compressive stress increase from 177 to 2640 with the increase of BST layer thickness. The BST layer with the tensile stress showed a comparably stable dielectric constant of 2400. In addition, the capacitance properties and the electrical breakdown strength of BST/LNO hetero-structure thin films are also thickness-dependent, respectively. The electrical breakdown strength reached a maximum value of 1237 kV/cm in the BST/LNO hetero-structure thin film with ~73 nm BST layer.

Over the next 50 years, the prevention and control of chronic diseases, such as obesity, cardiovascular disease, Alzheimer's disease, and many cancers, will be one of the most critical challenges in human health. Plant biochemistry and phytonutrient supplements are a promising complementary therapy for the management of chronic disease. Among them, Humulus lupulus has attracted special attention throughout the world because it contains numerous dietary phytochemicals that not only contribute to the aroma and flavor of beer but may also be used for medicinal purposes, as its properties include antiseptic, (an)aphrodisiac, anticancer, antiplatelet, antibacterial, antidiuretic, anti-inflammatory, sedative, hypnotic, and stomachic properties. This review sought to identify and understand the risk factors for chronic disease with a focus on two types of phytochemicals, bitter acids and xanthohumol. The goal was to understand how their metabolites promote human health and reduce the risk of chronic disease.

In this paper, a fabrication method for a patterned (Ba0.67Sr0.33TiO3, BST/LaNiO3, LNO)n thin-film multilayer is reported. The multilayer films were deposited by radio-frequency (RF) magnetron sputtering. A patterning technique of the as-prepared multilayer thin films was developed using ultrasonic-assisted wet etching. The scanning electron microscopy (SEM) surface images show that the developed technique can effectively etch the multilayer thin films deposited on SiO2 and Pt substrates without any residues. The etched multilayer thin film units of the size of 50 μm × 50 μm display clear and smooth etching edges, low distortions ( 900) and a relatively low loss tangent (

Application of 5-Aminolevulinic acid (ALA) to plants not only affects their growth, but also influences the nutritional values of plant organs. Oilseed rape (Brassica napus L.) is an important source of vegetable oil and various compounds benefiting human health. However, limited information is available regarding the effect of ALA on the growth of this important crop. Here, we investigated the consequence of ALA application on oilseed rape seedlings. We found that moderate ALA concentrations (0.5 or 1 mg/L) caused an increase in the dry weight of the seedling biomass and the contents of various bioactive compounds, i.e. soluble sugar, phenolic compounds, ascorbate, and glucosinolates etc, and the upregulated expressional levels of the genes encoding RuBisCO, namely, BnRBCL and BnRBCS, and other genes such as BnUGT79B1, BnMYB12 and MYB28 that regulate the synthesis of phenolic compounds and glucosinolates respectively. On the other hand, high ALA concentrations (5 and 10 mg/L) gave rise to oxidative stress that negatively affected oilseed rape growth, and caused deleterious effects by reducing various bioactive compounds, but increasing tocopherols that may serve as a stress mitigatory agent. With the high ALA concentrations, the ultrastructure of chloroplasts was notably damaged, featured with large starch grains and fewer plastoglobules.

A conjecture of Lerman, Montgomery and Sjamaar states that two singular symplectic reductions and are isomorphic if M / G is diffeomorphic to N / H as stratified spaces. We confirm this conjecture under the assumptions that the action $$G\times M\rightarrow M$$ is polar with a section N and generalized Weyl group H.

On urban scales, the detailed characteristics of land-use information and building properties are vital to improving the meteorological model. The WRF Model with high-spatial-resolution urban fraction (UF) and urban morphology (UM) is used to study the impacts of these urban canopy parameters (UCPs) on dynamical and thermal meteorological fields in two representative seasons in Guangzhou. The results of two seasons are similar and as follows. 1) The impacts of updated UF and UM are obvious on wind speed but minor on temperature and humidity. In the urban environment, the results with updated UF and UM are more consistent with observations compared with the default UCPs, which means the performance of the model has been improved. 2) The dynamical factors associated with wind speed are analyzed. Turbulent kinetic energy (TKE) is significantly affected by UM but little by UF. And both UF and UM are found to influence friction velocity U*. The UM and greater UF attained larger U*. 3) In addition, the thermal fields are analyzed. The UM and increased UF induce higher surface skin temperature (TSK) and ground heat flux in the daytime, indicating that more heat is transported from the surface to the soil. At night, more heat is transported from the soil to the surface, producing higher TSK. For sensible heat flux (HFX), greater UF induces larger HFX during the daytime. But the effects of UM are complex, which makes HFX decrease during the daytime and increase at night. Finally, larger UF attains lower latent heat in the daytime.

Open burning of crop residues is a strong seasonal source of air pollutants in many parts of China, but the large day-to-day variability of the associated emissions pose a great challenge for air quality forecasts. Here we developed back-propagation neural network (BPNN) ensembles to forecast the daily fire pixel counts in Southern China during the month of January. The BPNN ensembles were trained using daily assimilated surface meteorological data (including air temperature, relative humidity, pressure, and winds) and daily fire pixel observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) for the month of January during the years 2003–2012. We showed that the BPNN ensembles successfully forecasted the day-to-day variability and the interannual variability of fire pixel counts over Southern China in January of the years 2013–2015, with correlation coefficients of 0.6–0.8 against the MODIS observations. We used the forecasted daily fire pixel counts in January 2014 and January 2015 to scale the climatological January biomass burning emissions from the Fire Inventory from NCAR (FINN) and applied the resulting forecasted daily biomass burning emissions to drive the WRF-Chem regional air quality model. The use of BPNN-ensemble-forecasted daily biomass burning pollutant emissions led to significant improvements in the daily forecasts of PM2.5 concentrations in Southern China for January 2014, with the mean bias of the simulated surface PM2.5 concentrations reduced from −9.1% to −1.2%. We repeated the sensitivity simulations for January 2015 and also found a modest improvement when using the forecasted daily biomass burning pollutant emissions (mean bias of the simulated surface PM2.5 concentrations reduced from −5.8% to −2%). Our approach can be applied to other source regions of biomass burning emissions to improve the accuracy of daily air quality forecasts.

In this study, the Mycobacterium tuberculosis (MTB) latency-associated antigens Rv2660c, Rv1733c, Rv1813c, Rv2628, Rv2029c, and Rv2659c were compared regarding their immunogenicity and potential th...

Neolamarckia cadamba is a miracle tree species with considerable economic potential used as a timber wood, woody forage and traditional medicine resource. The present study aimed to establish an efficient protocol of plant regeneration and Agrobacterium-mediated genetic transformation for N. cadamba. Greenish callus were induced from different type explants when cultured on Murashige and Skoog’s (MS) medium supplemented with thidiazuron (TDZ) and kinetin (KT). The callus could differentiate into somatic embryos or adventitious shoots, and these two regeneration pathways often occurred in the same callus clumps. It was found that MS medium supplemented with 2 mg/L TDZ, 0.2 mg/L KT provided the most suitable medium for leaf explants to induce adventitious shoot, delivering a maximum regeneration frequency with a mean of 8.2 shoots per explant. The micro-shoots developed roots in MS supplemented with 0.05 mg/L α-naphthaleneacetic acid (NAA), and could be successfully acclimatized to a greenhouse with more than 90% survival. Based on this regeneration protocol, an Agrobacterium tumefaciens-mediated genetic transformation system was successfully developed for N. cadamba. Genetic transformation was obtained through the infection of leaf with A. tumefaciens strain GV3101 harboring a modified binary vector pCAMBIA1305 containing the marker genes β-glucuronidase (GUS) and fluorescent protein YFP. The presence of GUS in transformed plants was confirmed using PCR and histological stain, while the expression of YFP was confirmed through fluorescent microscopy and RT-PCR. Out of 276 putative transformants, 15 plants were found to be positive transgenic. Nevertheless, by adopting this protocol, positive transformed plants could be obtained within three months.

In this work, a multi-layer anode supported solid oxide fuel cell (SOFC) is designed and successfully prepared through sequential tape casting and co-firing. The single cell is consisted of NiO-3YSZ (3YSZ: 3 mol.% yttria doped zirconia) anode support, NiO-8YSZ (8YSZ: 8 mol.% yttria stabilized zirconia) anode functional layer, dense 8YSZ electrolyte layer, and porous 3YSZ cathode scaffold layer with infiltrated La0.6Sr0.4Co0.2Fe0.8O3-δ cathode. The clear interfaces and good contacts between each layer, without element inter-diffusion being observed, suggest that this sequential tape casting and co-firing is a feasible and successful route for anode supported single cell fabrication. This cell exhibits remarkable high open circuit voltage of 1.097 V at 800°C under room temperature humidified hydrogen, with highly dense and gastight electrolyte layer. It provides a power density of 360 mW/cm2 under operation voltage of 0.75 V at 800°C and a stable operation of ∼110 h at 750°C under current density of −300 mA/cm2. Furthermore, this cell also presents encouraging electrochemical responses under various anode hydrogen partial pressures and maintains high power output at low fuel concentrations.

A facile synthesis approach for metal-organic frameworks (MOFs) materials was studied for developing electrocatalysts with high electrochemical catalytic activity and stability. The prepared composite material contains two essential components: a predesigned bimetallic hybrid Zn/Co zeolitic imidazole frameworks (BMZIFs) and N-doped graphitic carbon (NGC) with various contents of carbon nanotubes (CNTs). Among which, NGC@CNTs-40 (100 mg NGC with 40 mg CNTs) exhibits the best oxygen reduction reaction (ORR) performance in alkaline media. In addition, NGC@CNTs-40 shows high surface area of 353.9 m2 g−1, coexisting micro/mesoporous N-doped carbon, low ID/IG ratio and abundant N atomic species. Remarkably, NGC@CNTs-40 exhibited a limiting current density of 5.66 mA cm−2 and a half-wave potential of 0.81 V, which is comparable with commercial Pt/C (5.22 mA cm−2 and 0.81 V) and most reported non-precious metal catalysts. Moreover, NGC@CNTs-40 exhibits better stability than Pt/C. The transferred electron number of NGC@CNTs-40 is 3.92, close to the ideal value of 4.0. The doping of CNTs into MOFs and the synergetic effect of Zn/Co-BMZIFs can enhance the conductivity of conventional MOFs and the blocked transfer of active substances in MOFs crystals, shedding new light on future applications.

Woody forage is a new feeding resource used worldwide, and silage is the main long-term storage, mediated by micro-organisms present during their processing. The objectives of our work were to evaluate the fermentation dynamics and to characterize the bacterial community of our typical woody forages. We selected four typical woody forages: paper mulberry (Broussonetia papyrifera), mulberry (Morus alba L.), moringa tree (Moringa oleifera), and Anthocephalus chinensis (Neolamarckia cadamba). The materials were ensiled and sampled after ensiling 1, 3, 5, 7, 15, 30, and 60 days. Our results indicate that woody forages have good forage properties with relatively high crude protein content and low neutral detergent fiber and acid detergent fiber content. However, the water soluble carbohydrate content in paper mulberry was considerably low (18.67 g kg−1), which makes ensiling difficult. The lactic acid and acetic acid contents in each of the four materials were reduced after 3 days of ensiling and increased again after 30 days of ensiling, with the exception of Anthocephalus chinensis. Anthocephalus chinensis and moringa tree were well-preserved after 7 and 60 days of ensiling, respectively, with low pH and ammonia nitrogen content. Cyanobacteria was predominant in moringa tree and Anthocephalus chinensis before ensiling, and Lactobacillus became dominant after 15 days of ensiling. Enterobacter dominated the paper mulberry and mulberry during fermentation process and accelerated their poor silage quality. Therefore, the conformity of bacterial community succession with ensiling parameters guaranteed the final quality of woody forage silages, and this might aid in controlling the manufacturing process.

Understanding the ecological and evolutionary mechanisms that shape a species' range is an important goal in evolutionary biology. Evidence indicates that mating system is an effective predictor of the global range of native species or naturalized alien plants, but the mechanisms underlying this predictability are not elaborated. Here, we develop a theoretical model to account for the ranges of plants under different mating systems based on migration-selection processes (an idea proposed by Haldane). The model includes alternation of gametophyte and sporophyte generations in one life cycle and the dispersal of haploid pollen and diploid seeds as vectors for gene flow. We show that the interaction between selfing rates and gametophytic selection determines the role of mating system in shaping a species' range. Selfing restricts the species' range under gametophytic selection in nonrandom mating systems, but expands the species' range under the absence of gametophytic selection in any mating system. Gametophytic selection slightly restricts the species' range in random mating. Both logarithmic and logistic models of population demography yield similar conclusions in the case of fixed or evolving genetic variance. The theory also helps to explain a broader relationship between mating system and range size following biological invasion or plant naturalization.

Improper reuse of manure could not only lead to low nitrogen-use efficiency but also result in environmental pollution. Therefore, we studied the effect of manure amendment with or without organisms (earthworm and bacteria) on soil nitrogen cycling, aiming to develop a more scientific way to reuse manure. In this study, six treatments, including control (CK), manure (M), manure + slurry (MS), manure + slurry + earthworm (MSE), manure + slurry + bacteria (MSB), and manure + slurry + earthworm + bacteria (MSEB) were divided into two groups to study the effect of manure and the effect of organism on the soil nitrogen pools and nitrogen cycling, respectively. The results showed that manure amendment coupled with organisms increased total nitrogen from 0.538 ± 0.06 to 1.380 ± 0.22 g kg ¹, and available nitrogen from 67.28 ± 5.22 to 113.11 ± 12.21 mg kg⁻¹, and improved soil organic nitrogen pool by increasing acid-hydrolyzable nitrogen (AHN) from 404 ± 39 to 974 ± 94 mg kg⁻¹ and non-acid-hydrolyzable nitrogen (NAHN) from 133 ± 26 to 406 ± 155 mg kg⁻¹. Based on the results of soil inorganic nitrogen and soil enzyme activities, we further found that earthworms and bacteria accelerated soil nitrogen cycling by stimulating soil mineralization (ammonification and nitrification) and nitrifier-denitrification, providing more available nitrogen to plants. Thus, we conclude that manure coupled with organisms would be a more efficient way to reuse manure via increasing soil nitrogen storage and availability simultaneously.

Toona ciliata (Meliaceae) is a rare, fast-growing commercial tree species that produces red timber with beautiful grains. It used to be widely distributed in the past, but few natural forests exist in the field now. Here, we tested 12 nuclear microsatellite markers derived from 551 individuals of 29 populations in China, and investigated the genetic diversity and population structure in T. ciliata. Our results revealed 146 alleles obtained from all of the populations studied here, with an average polymorphic information content of 0.723. The populations could be divided into two major genetic lineages using STRUTURE analysis: 14 and 15 populations from different provinces clustered in Western and Eastern genetic lineages, respectively. The genetic differentiation among the two genetic lineages was 28%. The genetic diversity of the Western lineage was higher than that of the Eastern lineage. Moreover, a Mantel test of the relationship between genetic and geographic distances revealed significantly positive correlations both among all 29 populations and within the Eastern genetic lineage, whereas there was no significant correlation in the Western genetic lineage. Therefore, in the conservation strategy of T. ciliatare sources, the two genetic lineages should be treated independently. To the best of our knowledge, these data are the first detailed characterization of the genetic structure and diversity of T. ciliata populations using nuclear microsatellite markers. The obtained results lay the foundation for preservation of the T. ciliata germplasm resources and support further artificial breeding efforts.

Hollow carbon nanofibers (HCNFs) are successfully fabricated by pyrolyzation of a polyaniline hollow nanofiber precursor. The as-prepared HCNFs as sodium storage anode materials exhibit a high reversible charge capacity of 326 mA h g-1 at 20 mA g-1, high rate capability (85 mA h g-1 at 1.6 A g-1) and superior cycling stability (a capacity retention of 70% even after 5000 cycles at 1.6 A g-1). Such a high performance of HCNFs can be ascribed to the special hollow structure characteristics; they possess a well fabricated electronic transport path and can shorten the ion diffusion distance. Therefore, the HCNFs can be regarded as promising anode materials for advanced sodium ion batteries (SIBs).

Rietveld refinement is used to investigate the crystal structure of prepared (0.965 – x)(K0.48Na0.52)NbO3–xBiInO3–0.035(Bi0.5Na0.5)ZrO3 (KNN-xBI-BNZ) ceramics. From refined results, the distortion degree of crystal structures in KNN-xBI-BNZ ceramics presents a rising trend with BiInO3 modification, which is in keeping with the results of diffuseness. The spontaneous polarization (Ps) is also calculated using refined structural parameters. The submicron domains are observed when x = 0.004, which presents good electrical properties (d33 = 317 pC/N, Tc = 336 °C) simultaneously. Excellent thermal stability of ceramics modified with BiInO3 is observed in a broad temperature range.

Hard carbon (HC) has been actively investigated as a high-capacity and low-cost anode material for sodium-ion batteries (SIBs); however, its sodium-storage mechanism has remained controversial, which imposes great difficulties in the design and construction of better microstructured HC materials. To obtain a deeper understanding of the Na-storage mechanism, we comparatively investigated electrochemical behaviors of HC and graphite for Na- and Li-storage reactions. The experimental results reveal that the Na-storage reaction on HC at a low-potential plateau proceeds in a manner similar to the Li+-insertion reaction on graphite but very differently from the Li+-storage process on HC, suggesting that the Na-storage mechanism of HC at a low-voltage plateau operates through the Na+ intercalation into the graphitic layers for the formation of sodium-graphite intercalation compounds (Na-GICs) and is consistent with the "adsorption-intercalation" mechanism. Our work might provide new insight for designing better HC materials of high-energy density SIBs.

Rice false smut is a fungal disease distributed worldwide and caused by Ustilaginoidea virens. In this study, we identified a putative ester cyclase (named as UvEC1) as being significantly upregulated during U. virens infection. UvEC1 contained a SnoaL-like polyketide cyclase domain, but the functions of ketone cyclases such as SnoaL in plant fungal pathogens remain unclear. Deletion of UvEC1 caused defects in vegetative growth and conidiation. UvEC1 was also required for response to hyperosmotic and oxidative stresses and for maintenance of cell wall integrity. Importantly, ΔUvEC1 mutants exhibited reduced virulence. We performed a tandem mass tag (TMT)-based quantitative proteomic analysis to identify differentially accumulating proteins (DAPs) between the ΔUvEC1-1 mutant and the wild-type isolate HWD-2. Proteomics data revealed that UvEC1 has a variety of effects on metabolism, protein localization, catalytic activity, binding, toxin biosynthesis and the spliceosome. Taken together, our findings suggest that UvEC1 is critical for the development and virulence of U. virens.

Background: The drumstick tree is a fast-growing multipurpose tree with a large biomass and high nutritional value. However, it has rarely been exploited as a protein source. This study investigated solid-state fermentation induced by Aspergillus niger, Candida albicans and Bacillus subtilis to obtain high-quality protein feed from drumstick leaf flour. Results: Solid-state fermentation induced significant changes in the nutritional composition of drumstick leaf flour. The concentrations of crude protein, small peptides and amino acids increased significantly after fermentation. The protein profile was also affected by the fermentation process. Macromolecular proteins in drumstick leaf flour were degraded, whereas other high molecular weight proteins were increased. However, the concentrations of crude fat, fiber, total sugar and reducing sugar were decreased, as were the anti-nutritional factors tannins, phytic acid and glucosinolates. After 24 h fermentation, the concentrations of total phenolics and flavonoids were increased. The antioxidant capacity was also significantly enhanced. Conclusions: The results suggested that the feed quality of drumstick leaves was greatly improved by solid-state fermentation.

Moringa oleifera Lam. (MO) is a fast-growing multi-purpose deciduous tree with high biomass and nutritional value. However, the presence of antinutritional factors, poor palatability, and indigestibility of Moringa oleifera leaf meal (MOLM) restrict its application to animal feed. This study aimed to obtain high-quality protein feeds via solid-state fermentation (SSF) of MOLM. The process conditions for increasing the true protein (TP) content using Aspergillus niger, Candida utilis and Bacillus subtilis co-cultures were optimized, and the chemical composition of MOLM was compared before and after fermentation. The results of this study showed that the highest TP content could be obtained through mixed-strain culture of A. niger, C. utilis and B. subtilis at a ratio of 1:1:2. The MOLM was inoculated with A. niger, followed by C. utilis and B. subtilis 24 h later. The optimized co-culture parameters were as follows: total inoculation size, 24%; temperature, 32 °C; fermentation time, 6.5 days; and initial water content, 60%. The maximum TP yield was 28.37%. Notably, in the fermented MOLM (FMOLM), the content of nutrients such as crude protein (CP), small peptides, and total amino acids (AAs) were significantly increased relative to unfermented MOLM, whereas the contents of crude fiber (CF), tannin, and phytic acid were significantly decreased. MOLM analysis using scanning electron microscopy (SEM) revealed that SSF disrupted the surface structure of MOLM, and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) indicated that macromolecular proteins were degraded. The in vitro protein digestibility (IVPD) of FMOLM was also improved significantly. Our findings suggest that multi-strain fermentation with A. niger, C. utilis and B. subtilis improves the nutritional quality of MOLM, rendering it a viable functional feedstuff for use in livestock industries in the future.

Despite the ubiquity of cypermethrin (CYP) stereoisomers in environment biota, the stereoisomeric selectivity of endocrine-disrupting potency of α-CYP, β-CYP, and θ-CYP has not been well studied. In this study, dual-luciferase reporter gene assays were adopted to analyze their potential endocrine-disrupting effects via four receptors (ERα, GRα, MR and RXR). The results showed that α-CYP was antagonistic to ERα, GRα, and MR with RIC20 of 9.1 × 10−7, 7.6 × 10−7, and 1.0 × 10−6 M, respectively. β-CYP exhibited only ERα-mediated agonistic activity with a REC20 of 2.1 × 10−6 M. None of the CYP stereoisomers interacted with RXR. Molecular docking indicated that α-CYP had the strongest binding capacity to GRα among the compounds. The expression levels of steroid hormone-related genes in human adrenocortical carcinoma (H295R) cells displayed that all three compounds inhibited the transcription of 3-βHSD, indicating the block of turning cholesterol into different hormones. Both α-CYP and β-CYP upregulated genes encoding estrogen- and aldosterone-forming enzymes including 17-βHSD, CYP19, STAR, and CYP11B2. Mortality and malformation toxicity assays in zebrafish embryos revealed that the order of toxicity was α-CYP > β-CYP > θ-CYP. Our results indicated that α-CYP may pose the strongest endocrine-disrupting effects. The data provided here will be helpful to systematically understand stereoisomeric selectivity in the endocrine-disrupting effects of cypermethrin.

Most initially perfect flowers of Toona ciliata Roem subsequently develop into functionally unisexual flowers and their relative positions in the same inflorescence could enhance the outcrossing system in this species. Here we investigated the mating system of this species. We used eight nuclear microsatellite markers and investigated the progeny of 125 mother trees from six populations naturally distributed in South China, with sample sizes ranging from 64 to 300 seeds. The multilocus outcrossing rate was 0.970 ± 0.063, and the single locus outcrossing rate was 0.859 ± 0.106, indicating the pattern of predominant outcrossing. Selfing was present in one population, but biparental inbreeding occurred in five populations. Inbreeding was absent in maternal parents, and correlations of selfing among families or among loci were generally insignificant. Positive correlation of paternity at multiple loci was significant in four populations, but was not consistent with the results at single loci. Population substructure occurred in male similarity between outcrosses only in one population. Population genetic differentaitaion was significant (Fst = 34.5%) and the effects of isolation-by-distance at the eight loci were significant among the six populations. These results provide evidence that self-comptability and inbreeding naturally occur in T. ciliata and indicate that inbreeding avoidance is necessary during genetic improvement and breeding of this endangered tree species.

Background Before studying gene expression of different organisms, it is important to determine the best reference gene. At present, the most accurate method of detecting gene expression is quantitative real-time PCR (RT-qPCR). With this method, reference genes that are stable in different biological systems and under different conditions can be obtained. Toona ciliata Roem (T. ciliata). is a valuable and fast-growing timber specie. In this study, 20 reference genes were identified using RT-qPCR, as a primary prerequisite for future gene expression analysis. Four different methods, geNorm, NormFinder, BestKeeper, and RankAggreg were used to evaluate the expression stability of the 20 candidate reference genes in various tissues under different conditions. Results The experimental results showed that TUB-α was the most stably expressed reference gene across all samples and UBC17 was the most stable in leaves and young stems under Hypsipyla robusta (H. robusta) and methyl jasmonate (MeJA) treatments. In addition, PP2C59 and UBC5B were the best-performing genes in leaves under H. robusta treatment, while HIS1 and ACT7 were the best reference genes in young stems. The two best reference genes were 60S-18 and TUB-α after treatment at 4 °C. The expression of HIS6 and MUB1 was the most stable under PEG6000 treatment. The accuracy of the selected reference genes was verified using the transcription factor MYB3 (TcMYB3) gene. Conclusions This is the first report to verify the best reference genes for normalizing gene expression in T. ciliata under different conditions, which will facilitate future elucidation of gene regulations in this species.

Neolamarckia cadamba, a member of the Rubiaceae family, is widely distributed throughout South Asia and South China. In order to acquire reliable and repeatable results, the use of a suitable internal reference gene to normalize the RT-qPCR data is essential. In this study, we reported the validation of housekeeping genes to identify the most suitable internal reference gene(s) for normalization of qPCR data obtained among different tissues (bud, leaf, cambium region) under different hormone stresses. Here, &Delta, Ct, geNorm, NormFinder, and BestKeeper analyses were carried out to analyze the normalization of qPCR data of twenty-one reference gene families (ACT, CAC, CYP, EF1&alpha, eIF, FPS1, FBK, GAPDH, RAN, PEPKR1, PP2A, RPL, RPS, RuBP, SAMDC, TEF, Tub-&alpha, Tub-&beta, UBCE, UBQ, UPL) including 43 genes. The results showed that FPS1, RPL, and FBK were the most stable reference genes across all of the tested samples. In addition, the expression of NcEXPA8, one gene of interest that plays an important role in regulating cell wall extension, under different phytohormone stresses was used to further confirm the validated reference genes. Taken together, our results provide guidelines for reference gene selection under different phytohormone stresses and a foundation for more accurate and widespread use of RT-qPCR in N. cadamba.

For two commonly used modified emulsified asphalts, styrene butadiene rubber (SBR) and styrene butadiene styrene (SBS), direct heating and low-temperature evaporation methods were respectively applied to obtain the asphaltic residues. Nanotechnology provides a great solution to road construction issues. However, the use of nanoparticles increases the durability of asphalts and enhances the performance of bitumen. Dynamic shear rheometer (DSR) was employed for temperature scanning test and multiple stress creep recovery (MSCR) test of the asphaltic residues. In this paper, the changes in the rheological properties of the asphaltic residues were compared and analyzed. The influence of evaporation temperature on the rheological properties of modified emulsified asphaltic residues obtained by evaporation was discussed. Evaporation tests showed that the higher the evaporation temperature, the larger the mass reduction of residues at the early stage and the shorter the time needed to reach stabilization. The solid contents of modified emulsified asphaltic residues obtained under different evaporation temperatures also differed. The solid content of asphaltic residues obtained under the evaporation temperature of 60 °C was closest to that by the low-temperature evaporation method. This indicated influence of the evaporation temperature on the solid content of asphaltic residues. Based on the results of temperature scanning test and MSCR test, there was a significant difference in the rheological properties of the asphaltic residues obtained by direct heating and low-temperature evaporation methods. The anti-deformation capacity under high temperature in asphaltic residues obtained at different evaporation temperatures varied more greatly. For SBS-modified emulsified asphalt, the rutting resistance under high temperature in residues obtained by the low-temperature evaporation method was better; however, the opposite was true for the SBR-modified emulsified asphalt. This indicated that the high-temperature evaporation method may overestimate the high-temperature properties of SBR-modified emulsified asphaltic residues and underestimate the high-temperature properties of SBS-modified emulsified asphaltic residues. For the emulsified asphalt samples, the appropriate method to obtain asphaltic residues that are closest to the actual road conditions should be optimized depending on the specific purposes.

Crystalline Ba0.3Sr0.7Zr0.18Ti0.82O3 (BSZT) thin film was grown on Pt(111)/Ti/SiO2/Si substrate using radio frequency (RF) magnetron sputtering. Based on our best knowledge, there are few reports in the literature to prepare the perovskite BSZT thin films, especially using the RF magnetron sputtering method. The microstructure of the thin films was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and capacitance properties, such as capacitance density, leakage behavior, and the temperature dependence of capacitance were investigated experimentally. The prepared perovskite BSZT film showed a low leakage current density of 7.65 &times, 10&minus, 7 A/cm2 at 60 V, and large breakdown strength of 4 MV/cm. In addition, the prepared BSZT thin film capacitor not only exhibits an almost linear and acceptable change (&Delta, C/C ~13.6%) of capacitance from room temperature to 180 &deg, C but also a large capacitance density of 1.7 nF/mm2 at 100 kHz, which show great potential for coupling and decoupling applications.

Storm separation is a key step when carrying out storm transposition analysis for Probable Maximum Precipitation (PMP) estimation in mountainous areas. The World Meteorological Organization (WMO) has recommended the step-duration-orographic-intensification-factor (SDOIF) method since 2009 as an effective storm separation technique to identify the amounts of precipitation caused by topography from those caused by atmospheric dynamics. The orographic intensification factors (OIFs) are usually developed based on annual maximum rainfall series under such assumption that the mechanism of annual maximum rainfalls is close to that of the PMP-level rainfall. In this paper, an alternative storm separation technique using rainfall quantiles, instead of annual maximum rainfalls, with rare return periods estimated via Regional L-moments Analysis (RLMA) to calculate the OIFs is proposed. Based on Taiwan&rsquo, s historical 4- and 24-h precipitation data, comparisons of the OIFs obtained from annual maximum rainfalls with that from extreme rainfall quantiles at different return periods, as well as the PMP estimates of Hong Kong from transposing the different corresponding separated nonorographic rainfalls, were conducted. The results show that the OIFs obtained from rainfall quantiles with certain rare probabilities are more stable and reasonable in terms of stability and spatial distribution pattern.

With rapid economic and industrial development, the potentially toxic element (PTE)pollution of farmlands in China has become increasingly serious. Based on the Hakanson potentialecological risk index (RI) and national food pollutant limit standards (GB 2762-2017), the effects ofexogenous potentially toxic elements (PTEs), i.e., arsenic (As) and mercury (Hg), on rice growthwere studied. Common varieties of hybrid (YY 538, CY 84) and conventional (XS 134, JH 218) ricewere grown in pots having representative paddy soil from Zhejiang Province, China. The resultsshowed that As and Hg in soil significantly inhibited growth, however, the plant height of hybridrice was less affected. Further, there were significant correlations between concentrations of PTEsin soil and rice grains, however, hybrid rice had a stronger ability to absorb and accumulate PTEs.The comprehensive potential ecological RI of soil PTEs was 39.4&ndash, 89.9, which is below the level of&lsquo, minor ecological hazard&rsquo, and the contribution rate of Hg was 79.9%&ndash, 84.2%, as such, Hg posed thegreatest potential ecological risk in the study area. The ecological risk limits of As and Hg in the safeproduction of different rice varieties decreased in the order XS 134 &gt, JH 218 &gt, YY 538 &gt, CY 84. Theecological risk limits of As and Hg for conventional rice were higher, and the risk limits of As andHg for hybrid rice were lower, than the limit of the soil environmental quality assessment index inthe national &ldquo, Soil quality control criteria for soil pollution in agricultural land (for trialimplementation) (Trial)&rdquo, (GB15618-2018). The health risk limit of soil As in the typical paddy soil ofChina decreased in the order XS 134 &gt, CY 84 &gt, YY 538. The health risk limit of Hg decreasedin the order XS 134 &gt, CY 84. The health risk limit of As was lower, whereas therisk limit of Hg was higher, than the limit of the soil environmental quality evaluation index in thenational &ldquo, Soil quality control criteria for soil pollution in agricultural land (for trial implementation)(Trial)&rdquo, (GB15618-2018).

Rhamnogalacturonan-II (RG-II) is structurally the most complex glycan in higher plants, containing 13 different sugars and 21 distinct glycosidic linkages. Two monomeric RG-II molecules can form an RG-II-borate diester dimer through the two apiosyl (Api) residues of side chain A to regulate cross-linking of pectin in the cell wall. But the relationship of Api biosynthesis and RG-II dimer is still unclear. In this study we investigated the two homologous UDP-D-apiose/UDP-D-xylose synthases (AXSs) in Arabidopsis thaliana that synthesize UDP-D-apiose (UDP-Api). Both AXSs are ubiquitously expressed, while AXS2 has higher overall expression than AXS1 in the tissues analyzed. The homozygous axs double mutant is lethal, while heterozygous axs1/+ axs2 and axs1 axs2/+ mutants display intermediate phenotypes. The axs1/+ axs2 mutant plants are unable to set seed and die. By contrast, the axs1 axs2/+ mutant plants exhibit loss of shoot and root apical dominance. UDP-Api content in axs1 axs2/+ mutants is decreased by 83%. The cell wall of axs1 axs2/+ mutant plants is thicker and contains less RG-II-borate complex than wild-type Col-0 plants. Taken together, these results provide direct evidence of the importance of AXSs for UDP-Api and RG-II-borate complex formation in plant growth and development.

To study the effects of citric acid on fermentation process of Amomum villosum silage, A. villosum was ensiled without or with 1%, 2% citric acid and fermentation parameters and bacterial diversity were analyzed after 3, 7, 14, 30 days ensiling, respectively. Citric acid treated silages had lower dry matter loss (1.83% vs 2.23%), pH (3.84 vs 6.02), ammonia-N (0.33 vs 1.79 g/kg DM) and coliform bacteria number (2.00 vs 7.27 log

Exploitation of heterosis is an efficient strategy to increase crop production, improve quality, and enhance resistance to biotic and abiotic stresses. However, heterosis shows significant genetic × environment effects. Nitrogen is an important nutrient that affects crop development and grain yield. Hybrid maize performs significantly and differently depending on the nitrogen conditions, but the genetic basis of maize heterosis under different nitrogen conditions is unclear. In this study, a test population comprising a set of single segment substitution lines (SSSLs) was used to identify heterotic loci (HL) for root-related traits of maize seedlings under two nitrogen conditions. We identified 80 HL for the root system and related traits in maize seedlings, consisting of 16, 18, 10, 11, 11, and 14 HL associated with root length (RL), root surface area (RSA), root average diameter (RAD), shoot dry weight (SDW), root dry weight (RDW), and plant height (PH), respectively. Among them, 13% of the HL were detected under both nitrogen conditions simultaneously, including the HLs hRL1b, hRL7, hRL9, hRSA7a, hRSA9a, hRAD1a, hSDW6, hSDW7a, hSDW7b, and hPH6a, but most of the HLs (87%) were not detected under both nitrogen conditions. The results indicated that, in maize, heterosis also exists in the interaction between genotype and nitrogen level.

A special case of the main result states that a complete $1$-connected Riemannian manifold $(M^n,g)$ is isometric to one of the models $\mathbb R^n$, $S^n(c)$, $\mathbb H^n(-c)$ of constant curvature if and only if every $p\in M^n$ is a non-degenerate maximum of a germ of smooth functions whose Riemannian gradient is a conformal vector field.