•We propose a hierarchical feature alignment method to learn robust features.•We improve the feature similarity along network layers with Wasserstein distance.•The method shows a robust ...generalization ability on adversarial examples.
Deep neural networks have demonstrated excellent performance in most computer vision tasks in recent years. However, they are vulnerable to adversarial perturbations generated by adversarial attacks. These human-imperceptible perturbations often lead to severe distortion in the high-dimensional intermediate feature space, which is one of the major reasons for the vulnerabilities in deep neural networks. Therefore, input images with perturbations can completely change the predictions of the networks in the decision space. To overcome this drawback, we propose to progressively align the intermediate feature representations extracted from the adversarial domain with feature representations extracted from a clean domain through domain adaptation. The difference between two feature distributions can be accurately measured via an optimal transport-based Wasserstein distance. Thus, the deep networks are forced to learn robust and domain-invariant feature representations, so that the gap between the different domains is minimized and that the networks are no longer easily fooled by diverse adversaries. Extensive evaluations are conducted on four classification benchmark datasets in white-box attack scenarios. The evaluation results demonstrate a significant performance improvement over several state-of-the-art defense methods.
A high lithium conductive MoS2/Celgard composite separator is reported as efficient polysulfides barrier in Li–S batteries. Significantly, thanks to the high density of lithium ions on MoS2 surface, ...this composite separator shows high lithium conductivity, fast lithium diffusion, and facile lithium transference. When used in Li–S batteries, the separator is proven to be highly efficient for depressing polysulfides shuttle, leading to high and long cycle stability. With 65% of sulfur loading, the device with MoS2/Celgard separator delivers an initial capacity of 808 mAh g−1 and a substantial capacity of 401 mAh g−1 after 600 cycles, corresponding to only 0.083% of capacity decay per cycle that is comparable to the best reported result so far. In addition, the Coulombic efficiency remains more than 99.5% during all 600 cycles, disclosing an efficient ionic sieve preventing polysulfides migration to the anode while having negligible influence on Li+ ions transfer across the separator. The strategy demonstrated in this work will open the door toward developing efficient separators with flexible 2D materials beyond graphene for energy‐storage devices.
A MoS2/Celgard separator is demonstrated to greatly improve cycle stability and Coulombic efficiency when used as separator in Li–S batteries, due to the high lithium conductivity and the stacked structure, which not only acts as ion sieves to block polysulfides, but also provides free spaces to accommodate various polysulfide intermediates via physiochemical interaction.
α,α-Disubstituted α-amino acids (α-AAs) have improved properties compared to other types of amino acids. They serve as modifiers of peptide conformation and as precursors of bioactive compounds. ...Therefore, it has been a long-standing goal to construct this highly valuable scaffold efficiently in organic synthesis and drug discovery. However, access to α,α-disubstituted α-AAs is highly challenging and largely unexplored due to their steric constraints. To overcome these, remarkable advances have been made in the last decades. Emerging strategies such as synergistic enantioselective catalysis, visible-light-mediated photocatalysis, metal-free methodologies and CO
fixation offer new avenues to access the challenging synthesis of α,α-disubstituted α-AAs and continuously bring additional contributions to this field. This review article aims to provide an overview of the recent advancements since 2015 and discuss existing challenges for the synthesis of α,α-disubstituted α-AAs and their derivatives.
Prostaglandins have garnered significant attention from synthetic chemists due to their exceptional biological activities. In this report, we present a concise chemoenzymatic synthesis method for ...several representative prostaglandins, achieved in 5 to 7 steps. Notably, the common intermediate bromohydrin, a radical equivalent of Corey lactone, is chemoenzymatically synthesized in only two steps, which allows us to complete the synthesis of prostaglandin F
in five steps on a 10-gram scale. The chiral cyclopentane core is introduced with high enantioselectivity, while the lipid chains are sequentially incorporated through a cost-effective process involving bromohydrin formation, nickel-catalyzed cross-couplings, and Wittig reactions. This cost-efficient synthesis route for prostaglandins holds the potential to make prostaglandin-related drugs more affordable and facilitate easier access to their analogues.
Water availability and nutrient-status of soils play crucial roles in seedling establishment and plant survival in coal-spoiled areas worldwide. Restoration of spoils pertains to the application of ...proper doses of nutrients and water, and selection of particular plant species for efficient revegetation. This study aimed at examining the potential effects of different combinations of soil-water and fertilizers (nitrogen, N and phosphorus, P) on morpho-physiological and biochemical attributes of Amorpha fruticosa grown in coal-mined spoils. Three factors five-level central-composite-design with optimization technique response surface methodology (rsm) was used to optimize water irrigation and fertilizer application strategies.
Our results revealed a strong correlation between experimental data and predicted values developed from the rsm model. The best responses of A. fruticosa in terms of plant height, stem diameter, root length, and dry biomass were observed under a high-water regime. Low-water regime caused a notable reduction in growth-associated parameters, and fertilization with either N or P did not show positive effects on those parameters, indicating that soil-water was the most influential factor for growth performance. Leaf water potential, gas-exchange parameters, and chlorophyll content significantly increased under high levels of soil-water, N and P, suggesting a synergistic effect of these factors for the improvement of photosynthesis-related parameters. At low soil-water contents and N-P fertilizer application levels, enhanced accumulation of malondialdehyde and proline indicated that A. fruticosa suffered from oxidative and osmotic stresses. Amorpha fruticosa also responded to oxidative stress by accelerating the activities of superoxide dismutase, catalase, and peroxidase. The effects of both fertilizers relied on soil-water, and fertilization was most effective under well-watered conditions. The maximum growth of A. fruticosa was observed under the combination of soil-water, N-dose and P-dose at 76% field capacity, 52.0 mg kg
and 49.0 mg kg
, respectively.
Our results demonstrate that rsm effectively designed appropriate doses of water and N-P fertilizer to restore coal-spoiled soils. Furthermore, A. fruticosa responded to low-water and fertilizer-shortage by upregulating defensive mechanism to avoid damage induced by such deficiencies. Finally, our findings provide effective strategies for revegetation of coal-contaminated spoils with A. fruticosa using appropriate doses of water and N-P fertilizers.
Single rich-stimuli-responsive organometallic polymers are considered to be the candidate for ultrahigh information storage and anti-counterfeiting security. However, their controllable synthesis has ...been an unsolved challenge. Here, we report the rapidly sequence-controlled electrosynthesis of organometallic polymers with exquisite insertion of multiple and distinct monomers. Electrosynthesis relies on the use of oxidative and reductive C-C couplings with the respective reaction time of 1 min. Single-monomer-precision propagation does not need protecting and deprotecting steps used in solid-phase synthesis, while enabling the uniform synthesis and sequence-defined possibilities monitored by both UV-vis spectra and cyclic voltammetry. Highly efficient electrosynthesis possessing potentially automated production can incorporate an amount of available metal and ligand species into a single organometallic polymer with complex architectures and functional versatility, which is proposed to have ultrahigh information storage and anti-counterfeiting security with low-cost coding and decoding processes at the single organometallic polymer level.
•14 frozen soil thermal conductivity (FSTC) algorithms in land surface models were reviewed.•These 14 FSTC algorithms were evaluated with FSTC measurements at temperature ≤−4 °C.•The Becker 1992 ...algorithm performed the based on measured FSTC.•The 14 FSTC algorithms were incorporated into the SHAW model for evaluation.•No algorithms perform well, with the average bias ranging from −2.2 to 2.8 °C and −0.08 to 0.1 cm3 cm−3.
Frozen soil thermal conductivity (FSTC, λeff) is a critical thermophysical property that is required for a variety of science and engineering applications. Measurements of λeff in frozen soils are prone to errors because the currently available thermal methods result in phase change (i.e., thawing and refreezing of ice) that affects the estimated λeff, especially near the freezing point of soil water (e.g., −4 to 0 °C) where rapid phase change occurs. In addition, measured λeff data are few compared to other physical properties. Therefore, many FSTC algorithms have been developed and a few of them have been incorporated in numerical simulation programs for calculating λeff. However, large discrepancies between simulated and observed soil thermal regimes have been reported. Previous studies either evaluated the performance of a few FSTC algorithms with limited λeff or simply compared the performance of the algorithms in numerical simulation programs. No study has been performed to systematically assess the performance of the FSTC algorithms included in numerical simulation programs with both observations and model simulations. In this study, 14 FSTC algorithms incorporated in various numerical simulation programs were evaluated with a compiled dataset consisting of 331 λeff measurements on 27 soils from seven studies made at temperatures on or below −4 °C. The Becker 1992 algorithm provided the best estimates of the λeff measurements, but the accuracy of the estimates was not good (i.e., RMSE = 0.46 W m−1 °C−1, Bias = -0.04 W m−1 °C−1 and NSE = 0.51). These FSTC algorithms were also incorporated in the Simultaneous Heat and Water (SHAW) model to compare their effects on the simulating soil temperature and water content at two field sites with contrasting soil textures in USA. The simulation results showed that the average bias of simulated and observed soil temperature for all depths ranged from −2.2 to 2.8 °C and the average differences of liquid water content ranged from −0.08 to 0.1 cm3 cm−3. Generally no FSTC algorithm combined with the SHAW model satisfactorily estimated the dynamic soil thermal regime. Perspectives on future studies are discussed.
In order to improve the decorative properties of Magnesium-Glass-Board (MGB), the surface morphology and decoration performance of MGB, are studied in detail by using profilometer, microscope and ...SEM, and the influence of its characterization, such as surface roughness, surface porosity and wettability, on decorative properties of MGB is analyzed by comparing with medium density fiberboard (MDF) and medium density particleboard (MDP). The results first showed that the surface of MGB has a porous structure, but MDF and MDP are not, resulting in a poor decorative performance of MGB. Second, it is found that the surface wettability of MGB is better than others. Third, the hot-pressing parameters including pressure, temperature and time have different influence on decorative performance of MGB during hot-pressing experiment. Finally, the surface bonding strength is positively correlated with pressure, but not with temperature and time. In general, a higher surface bonding strength led to a better decorative performance of MGB. The furthermore research can concentrate on the modification method of the MGB's surface according to this paper's conclusion to improve the lamination performance of melamine paper.
Water chickweed (Myosoton aquaticum (L.)) is a dicot broadleaf weed that is widespread in winter fields in China, and has evolved serious resistance to acetolactate synthase (ALS) inhibiting ...herbicides.
We identified a M. aquaticum population exhibiting moderate (6.15-fold) resistance to tribenuron-methyl (TM). Target-site ALS gene sequencing revealed no known resistance mutations in these plants, and the in vitro ALS activity assays showed no differences in enzyme sensitivity between susceptible and resistant populations; however, resistance was reversed by pretreatment with the cytochrome P450 (CYP) monooxygenase inhibitor malathion. An RNA sequencing transcriptome analysis was performed to identify candidate genes involved in metabolic resistance, and the unigenes obtained by de novo transcriptome assembly were annotated across seven databases. In total, 34 differentially expressed genes selected by digital gene expression analysis were validated by quantitative real-time (qRT)-PCR. Ten consistently overexpressed contigs, including four for CYP, four for ATP-binding cassette (ABC) transporter, and two for peroxidase were further validated by qRT-PCR using additional plants from resistant and susceptible populations. Three CYP genes (with homology to CYP734A1, CYP76C1, and CYP86B1) and one ABC transporter gene (with homology to ABCC10) were highly expressed in all resistant plants.
The mechanism of TM resistance in M. aquaticum is controlled by NTSR rather than TSR. Four genes, CYP734A1, CYP76C1, CYP86B1, and ABCC10 could play essential role in metabolic resistance to TM and justify further functional studies. To our knowledge, this is the first large-scale transcriptome analysis of genes associated with NTSR in M. aquaticum using the Illumina platform. Our data provide resource for M. aquaticum biology, and will facilitate the study of herbicide resistance mechanism at the molecular level in this species as well as in other weeds.
Effective soil thermal conductivity (
λ
eff
) describes the ability of a multiphase soil to transmit heat by conduction under unit temperature gradient. It is a critical parameter for environmental ...science, earth and planetary science, and engineering applications. Numerous models are available in the literature, but their applicability is generally restricted to certain soil types or water contents (
θ
). The objective of this study was to develop a new model in the similar form of the
Johansen 1975
model to simulate the
λ
eff
(
θ
) relationship of soils of various soil textures and water contents. An exponential type model with two parameters is developed and a new function for calculating dry soil thermal conductivity is presented. Performance of the new model and six other normalized models were evaluated with published datasets. The results show that the new model is able to well mimic
λ
eff
(
θ
) relationship of soils from sand to silt loam and from oven dry to full saturation. In addition, it has the best performance among the seven models under test (with root-mean-square error of 0.059 W m
−1
°C
−1
, average deviations of 0.0009 W m
−1
°C
−1
, and Nash–Sutcliffe efficiency of 0.994). The new model has potential to improve the reliability of soil thermal conductivity estimation and be incorporated into numerical modeling for environmental, earth and engineering studies.
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