Past studies have already determined that selenium (Se) is very effective in alleviating cell oxidative damage caused by various abiotic stresses in plants. Past studies have also indicated other ...physiological pathways by which Se may benefit plants. In order to better understand the full array of potential applications for Se in agriculture, this study investigated the influence of Se on carbohydrate and nitrogen (N) metabolism in potato plants (Solanum tuberosum L. cv. Sante) grown under cadmium (Cd) and/or arsenic (As) toxicity. Potato plants were grown in a growth chamber and fertigated with Hoagland nutrient solution with or without Se (9 μM). After 48-d of growth under Cd (40 μM) and/or As (40 μM) stress, carbohydrate and N metabolism in leaves, roots and stolons were measured. For carbohydrate metabolism, various sugars—i.e., sucrose, starch, glucose, fructose, and total soluble sugar contents (TSSC)—and the activities of enzymes associated with sucrose metabolism and glycolysis—i.e., acid invertase (AI), neutral invertase (NI), sucrose-synthetase (SS), sucrose phosphatesynthetase (SPS), fructokinase (FK), hexokinase (HK), phosphofructokinase (PFK), and pyruvatekinase (PK)—were measured. For N metabolism, NO3−, NO2− and NH4+ contents along with the enzymatic activities of nitrate reductase (NRA), nitrite reductase (NiRA), glutamine-synthetase (GS), and glutamate-synthetase (GOGAT) were measured. Overall, Cd and/or As treatments had reduced plant growth relative to those plants grown without heavy metal toxicity, due to hindered photosynthesis and alterations in N metabolism and glycolysis. Regarding N metabolism, heavy metal toxicity caused a reduction in NO3− and NO2− content and NRA and NiRA enzymatic activity and enhanced NH4+ content and GDH activity in leaves, roots and stolons. Regarding glycolysis, the activity of enzymes of glycolysis—i.e., FK, HK, PFK, and PK—were also reduced. In the C metabolism study, plants combatted Cd and As toxicity naturally by an adaptation mechanism which caused an increase in soluble sugars (fructose, glucose, sucrose) by increasing NI, SS and SSP enzymatic activity. Supplementation with Se in the Cd and/or As treatments in the carbohydrate and N metabolism studies improved plant growth. Selenium supplementation in the Cd and As treatments decreased Cd and/or As content in the plant tissue and alleviating the Cd- and/or As-induced toxicity by enhancing the C-metabolism adaptation mechanism. Applying Se to Cd and As treatments also decreased nitrogen losses by hindering Cd- and As-induced changes in the N-metabolism. Se also limited Cd and As accumulation in the plant tissue by the antagonistic effect between Cd/Se and As/Se in the roots. The results of this study indicate that in the presence of Cd and/or As. soil toxicity, Se may be a powerful tool for promoting plant growth.
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•Cd and/or As enhanced the enzymes of carbohydrate metabolism except AI activity.•Sugars and starch contents were lowered by Cd and/or As stress.•Cd and/or As toxicity limited the NO3− and NO2− contents but enhanced NH4+ content.•Se alleviated Cd and/or As toxicity by modulating the glycolysis.•Se reduced oxidative damage by limiting the Cd and As uptake through roots.
A recent theoretical work indicates that intermetallic materials LiMnZ (Z = N, P) with a half-Heusler structure exhibit half-metallic (HM) behaviors at their strained lattice constants, and the ...magnetic moments of these alloys are expected to reach as high as 5 μ
per formula unit. (Damewood et al.
,
, 064409). This work inspired us to find new Heusler-based half-metals with the largest magnetic moment. With the help of the first-principles calculation, we reveal that XCrZ (X = K, Rb, Cs; Z = S, Se, Te) alloys show a robust, half-metallic nature with a large magnetic moment of 5 μ
at their equilibrium and strained lattice constants in their most stable phases, while the excellent HM nature of LiCrZ (Z = S, Se, Te) alloys can be observed in one of their metastable phases. Moreover, the effects of uniform strain in LiCrZ (Z = S, Se, Te) alloys in type II arrangement have also been discussed.
•The deep learning GRU network is first used as surrogate model in hydrology.•High-dimensional parameter auto-calibration is performed.•Time-variant features of MODFLOW parameters are captured via ...proposed method.•Proposed GRU surrogate technique considerably reduces the computational cost.
The correlations of the multiple time-series outputs of an original simulation model are difficult to take into account using traditional surrogate model techniques. This study proposes a novel surrogate model based on a deep learning structure called gated recurrent unit (GRU) network, with the aim of developing a substitute for an original simulation model with large temporal and spatial variations and of improving the computational efficiency of studies that require thousands of model executions. First, a numerical groundwater flow model was established as the original simulation model, and then, a GRU network was trained using the two-dimensional outputs of the original simulation model. After this, the parameter was auto-calibrated by combining the GRU surrogate with the particle swarm optimization (PSO) algorithm. Furthermore, a Sobol’ sensitivity analysis was conducted for multiple time nodes. The results demonstrate that the GRU-based surrogate model exhibits a high accuracy and the ability to manage problems with multiple time-series outputs. The GRU surrogate combined with the PSO algorithm has an excellent ability to implement high-dimensionality parameter calibration tasks. In addition, the Sobol’ sensitivity analysis based on the GRU surrogate exhibits a sufficient capacity to capture the temporal characteristics of the simulation model parameters. The surrogate based on the GRU also significantly reduces the computational costs. The GRU-based surrogate technique not only can facilitate the groundwater studies, but can also have an excellent application potential for other long-term water resource managements.
•Electrochemical behavior of stainless steels with diverse metallographic phases is studied.•Passivation behavior is examined using potentiodynamic tests and EIS measurements.•Metallographic phases ...affect passivating films and electrochemical machining performances.•SUS316L exhibits distinct behavior in neutral solutions compared to the SUS430 and SUS 440C.
To investigate the anodic dissolution of stainless steels with diverse metallographic phases and its impact on micro electrochemical machining (micro-ECM) performance, the electrochemical behavior of representative ferritic stainless steel (SUS430), martensite stainless steel (SUS440C), dual-phase stainless steel (2205 DSS), and austenite stainless steel (SUS316L) in neutral solutions were examined by analyzing potentiodynamic results and electrochemical impedance spectroscopy (EIS). The growth and chemical compositions of passive films on the stainless steels were evaluated using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). EIS results indicate that the passive film formed on SUS430 (ferritic phase) and SUS440C (martensite phase) in NaClO3 exhibited greater stability compared to that formed in NaNO3, which is attributed to the thicker passive film formed in NaClO3 and higher Fe2+/Fe3+ ratio as well as Cr2O3/Cr(OH)3 ratio. The SUS316L (austenite phase) exhibits almost the opposite behavior compared to the SUS430 and SUS 440C. The impact of the electrochemical behavior on the evolution of dissolution region and surface topography was discussed from the micro-ECM experimental results. The 2205 DSS exhibits a much higher corrosion resistance, but local corrosion zones were observed at the edges of microgrooves, leading to approximate material removal rate values compared to single-phase steels. The metallographic phases influence the composition, structure, and density of the passive films, and determine the ECM performance. This study demonstrates the relationships between the MRRs and the metallographic phases of stainless steel, which provides a feasible idea for optimizing the matches of the electrolyte composition and stainless steel workpiece.
In this paper, we explore an impulsive stochastic infected predator-prey system with Lévy jumps and delays. The main aim of this paper is to investigate the effects of time delays and impulse ...stochastic interference on dynamics of the predator-prey model. First, we prove some properties of the subsystem of the system. Second, in view of comparison theorem and limit superior theory, we obtain the sufficient conditions for the extinction of this system. Furthermore, persistence in mean of the system is also investigated by using the theory of impulsive stochastic differential equations (ISDE) and delay differential equations (DDE). Finally, we carry out some simulations to verify our main results and explain the biological implications.
Abstract
The topological materials have attracted much attention for their unique electronic structure and peculiar physical properties. ZrTe
5
has host a long-standing puzzle on its anomalous ...transport properties manifested by its unusual resistivity peak and the reversal of the charge carrier type. It is also predicted that single-layer ZrTe
5
is a two-dimensional topological insulator and there is possibly a topological phase transition in bulk ZrTe
5
. Here we report high-resolution laser-based angle-resolved photoemission measurements on the electronic structure and its detailed temperature evolution of ZrTe
5
. Our results provide direct electronic evidence on the temperature-induced Lifshitz transition, which gives a natural understanding on underlying origin of the resistivity anomaly in ZrTe
5
. In addition, we observe one-dimensional-like electronic features from the edges of the cracked ZrTe
5
samples. Our observations indicate that ZrTe
5
is a weak topological insulator and it exhibits a tendency to become a strong topological insulator when the layer distance is reduced.
Relative pose measurement for noncooperative objects is an important part of 3D shape recognition and motion tracking. The methods based on scanning point clouds have better environmental ...adaptability and stability than image-based methods. However, the discrete points obtained from a continuous surface are sparse, which leads to point-to-point dislocations in the overlapping area and seriously reduces the accuracy. Therefore, this paper proposed a relative-pose-measurement algorithm based on double-constrained intersurface mutual projections. First, the initial corresponding set was constructed using mutual projections between the areas with similar feature descriptors, and then the final corresponding set was determined through the rigid-transformation-consistency constraint to improve the accuracy of the matchings and achieve a high-accuracy relative pose measurement. In the Stanford dataset, the rotation error and translation error were reduced by 19.3% and 13.4%, respectively. Furthermore, based on the proposed evaluation method, which separated the error of the pose-measurement algorithm from that of the instrument, the experiments were carried out with a self-made swept-frequency interferometer. The rotation error was reduced by 39.8%, and the surface deviation was reduced by 4.9%, which further proved the advancement of the method.
The recent discovery of high-temperature superconductivity in iron-based compounds has attracted much attention. How to further increase the superconducting transition temperature (T(c)) and how to ...understand the superconductivity mechanism are two prominent issues facing the current study of iron-based superconductors. The latest report of high-T(c) superconductivity in a single-layer FeSe is therefore both surprising and significant. Here we present investigations of the electronic structure and superconducting gap of the single-layer FeSe superconductor. Its Fermi surface is distinct from other iron-based superconductors, consisting only of electron-like pockets near the zone corner without indication of any Fermi surface around the zone centre. Nearly isotropic superconducting gap is observed in this strictly two-dimensional system. The temperature dependence of the superconducting gap gives a transition temperature T(c)~ 55 K. These results have established a clear case that such a simple electronic structure is compatible with high-T(c) superconductivity in iron-based superconductors.
An electrochemical aptasensor for trace detection of aflatoxin B1 (AFB1) was developed by using an aptamer as the recognition unit while adopting the telomerase and EXO III based two-round signal ...amplification strategy as the signal enhancement units. The telomerase amplification was used to elongate the ssDNA probes on the surface of gold nanoparticles, by which the signal response range of the signal-off model electrochemical aptasensor could be correspondingly enlarged. Then, the EXO III amplification was used to hydrolyze the 3′-end of the dsDNA after the recognition of target AFB1, which caused the release of bounded AFB1 into the sensing system, where it participated in the next recognition-sensing cycle. With this two-round signal amplified electrochemical aptasensor, target AFB1 was successfully measured at trace concentrations with excellent detection limit of 0.6*10−4ppt and satisfied specificity due to the excellent affinity of the aptamer against AFB1. Based on this designed two-round signal amplification strategy, both the sensing range and detection limit were greatly improved. This proposed ultrasensitive electrochemical aptasensor method was also validated by comparison with the classic instrumental methods. Importantly, this hetero-enzyme based two-round signal amplified electrochemical aptasensor offers a great promising protocol for ultrasensitive detection of AFB1 and other mycotoxins by replacing the core recognition sequence of the aptamer.
•Electrochemical biosensor for AFB1 was developed using aptamer as recognition probe.•Hetero-enzyme-based two-round signal amplification was adopted for sensing improvement.•Sensing range was improved 3 orders and LOD improved 1000-fold for AFB1 detection.
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