Searching for superconductivity with T
near room temperature is of great interest both for fundamental science & many potential applications. Here we report the experimental discovery of ...superconductivity with maximum critical temperature (T
) above 210 K in calcium superhydrides, the new alkali earth hydrides experimentally showing superconductivity above 200 K in addition to sulfur hydride & rare-earth hydride system. The materials are synthesized at the synergetic conditions of 160~190 GPa and ~2000 K using diamond anvil cell combined with in-situ laser heating technique. The superconductivity was studied through in-situ high pressure electric conductance measurements in an applied magnetic field for the sample quenched from high temperature while maintained at high pressures. The upper critical field Hc(0) was estimated to be ~268 T while the GL coherent length is ~11 Å. The in-situ synchrotron X-ray diffraction measurements suggest that the synthesized calcium hydrides are primarily composed of CaH
while there may also exist other calcium hydrides with different hydrogen contents.
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•A tyrosinase biosensor was developed for ultrasensitive detection of phenolic contaminants.•The biosensor was based on the electroactive tyrosinase-immobilized phase-change ...microcapsules.•The biosensor achieved enhanced biosensing performance by thermal buffering at high temperatures.•The biosensor presents a high sensitivity and low detection limit for determining catechol.•The biosensor finds great potential for detection of phenolic contaminants in harsh environments.
Aiming at enhancing the detection of phenolic contaminants in high-temperature environments, we developed a thermoregulatory electrochemical biosensor based on the tyrosinase-immobilized electroactive phase-change microcapsules. The microcapsules were fabricated by engulfing n-eicosane as a phase-change material core in a TiO2 shell, followed by depositing with an electroactive hybrid layer comprising the polypyrrole matrix and tyrosinase-immobilized Fe3O4 nanoparticles. The resultant microcapsules show a well-defined core–shell microstructure and a regular spherical morphology, together with the desired chemical compositions and structures. Acting as a biosensing electrode material, the microcapsules exhibit a high latent heat capacity of around 150 J/g to implement microenvironmental temperature regulation for the biosensor through reversible phase transitions of their n-eicosane core. This enables the developed biosensor to obtain a higher enzyme activity and more sensitive biosensing performance at high assay temperatures when compared to conventional tyrosinase biosensors, resulting in a high sensitivity of 0.102 (µA·L)/µmol and a lower detection limit of 3.409 µmol/L for catechol detection. Based on a unique integration of phase-change microcapsules and immobilized tyrosinase in the working electrode, the electrochemical biosensor developed in this study has found a practical application for high-sensitive reorganization and high-accurate determination of phenolic contaminants in industrial wastewaters over a wide working temperature range.
In this article, a control strategy based on linear active disturbance rejection control (LADRC) is proposed for the dual-stator winding induction generator (DWIG) ac power system, in order to solve ...the problems of contradiction between tracking ability and dynamic performance with proportional-integral controller. Based on the rotor-flux-oriented coordinate system, the dynamic mathematic model of the output ac voltage of power winding (PW) is established. The load disturbance on the PW side and the variation of the system parameters are regarded as the total disturbance, which is observed and compensated by linear extended state observer (LESO) and linear state error feedback (LSEF), respectively. By analyzing the swiftness and disturbance-rejection ability with different bandwidths of LESO, the ac voltage LADRC controller is first designed for DWIG. The stability and performance analysis with different controller parameters is given and the robustness of the proposed controller under the parameter mismatch is investigated. Both simulation and experiments show that the proposed LADRC has a better tracking ability and dynamic performance. Moreover, the proposed LADRC also has strong robustness under the parameter mismatch.
Dynamic crystals with directional deformations in response to external stimuli through molecular reconfiguration, are observed predominantly in certain organic crystals and metal complexes. ...Low-dimensional hybrid halides, resemble these materials due to the presence of strong hydrogen bonds between bulky organic moieties and inorganic units, whereas their dynamic behavior remains largely unexplored. Here we show that a one-dimensional hybrid halide (MV)BiBr5 (MV = methylviologen) undergoes an isosymmetric phase transition at hydrostatic pressure of 0.20 GPa, accompanied by a remarkable length expansion of 20–30% and red to dark yellow color change. Unexpectedly, the backward transition can be fully reversed by mechanical stimulation rather than decompression. In the high-pressure phase, the coexistence of strong Bi3+ lone pair stereochemical activity and large reorientations of the planar MV2+ cations, together with the newly formed CH···Br hydrogen interactions, are the structural features that facilitate microscopic changes and stabilize the metastable high-pressure phase at ambient conditions.Dynamic behavior is typically observed in organic crystals and metal complexes, but is rarely found in hybrid halides. Here, the authors find a pressure-induced irreversible phase transition with remarkable shape and color changes in a 1D halide.
Superconductivity at megabar pressures has recently attracted interest in the context of hydrides. Here, the authors demonstrate superconductivity up to 26 K at high pressure in elemental titanium, ...and further suggest that electron correlations contribute to the high T c.
The excessive use of chemical herbicides has resulted in evolution of herbicide-resistant weeds. Cytochrome P450 monooxygenases (P450s) are vital detoxification enzymes for herbicide-resistant weeds. ...Herein, we confirmed a resistant (R) Polypogon fugax population showing resistance to quizalofop-p-ethyl, acetolactate synthase (ALS)-inhibiting herbicide pyroxsulam, and several other ACCase (acetyl-CoA carboxylase)-inhibiting herbicides. Molecular analysis revealed no target-site gene mutations in the R population. Foliar spraying with malathion clearly reversed the quizalofop-p-ethyl phytotoxicity. Higher level of quizalofop-p-ethyl degradation was confirmed in the R population using HPLC analysis. Subsequently, RNA-Seq transcriptome analysis indicated that the overexpression of CYP89A2 gene appeared to be responsible for reducing quizalofop-p-ethyl phytotoxicity. The molecular docking results supported a metabolic effect of CYP89A2 protein on most herbicides tested. Furthermore, we found that low doses of herbicides stimulated the rhizosphere enzyme activities in P. fugax and the increase of rhizosphere dehydrogenase of R population may be related to its resistance mechanism. In summary, our research has shown that metabolic herbicide resistance mediated by CYP89A2, contributes to quizalofop-p-ethyl resistance in P. fugax.
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•Polypogon fugax has evolved cross-resistance to herbicide in China.•P450s-mediated metabolism was responsible for reducing herbicide accumulation.•Malathion can remediate the phytotoxicity of herbicide to the herbicide-resistant plant.•P. fugax CYP89A2 gene played significant role in herbicide metabolism and detoxification.•Rhizosphere enzyme activities may be related to the herbicide resistance mechanism.
Asia minor bluegrass (
) is a common and problematic weed throughout China.
that is often controlled by acetyl-CoA carboxylase (ACCase) inhibitors in canola fields. Herein, we confirmed a
population ...(R) showing resistance to all ACCase inhibitors tested with resistance indexes ranging from 5.4-18.4. We further investigated the resistance mechanisms of this R population. Molecular analyses revealed that an amino acid mutation (Asp-2078-Gly) was present in the R population by comparing
gene sequences of the sensitive population (S). In addition, differences in susceptibility between the R and S population were unlikely to be related to herbicide metabolism. Furthermore, a new derived cleaved amplified polymorphic sequence (dCAPS) method was developed for detecting the Asp-2078-Gly mutation in
efficiently. We found that 93.75% of plants in the R population carried the Asp-2078-Gly mutation, and all the herbicide-resistant phenotype of this R population is inseparable from this mutation. This is the first report of cross resistance to ACCase inhibitors conferred by the Asp-2078-Gly target-site mutation in
ax. The research suggested the urgent need to improve the diversity of weed management practices to prevent the widespread evolution of herbicide resistance in
ax in China.
In this paper, the five-phase dual stator-winding induction generator dc generating system with the static excitation controller is presented, and two kinds of control strategies for this system are ...proposed. In this generator, the cage-type rotor is employed, and two sets of five-phase windings are placed in the stator, namely, the power winding and control winding. Using the instantaneous power theory, the control-winding-flux-oriented control (CWFOC) strategy without harmonic injection is obtained. To improve power density, the CWFOC with harmonic injection is proposed as well. For these two strategies, the detailed implementation is studied. The results (simulation and experiment) support the correctness and effectiveness of the proposed control strategies, and the corresponding results show that, using the CWFOC strategy with harmonic injection, the output power of this system can be improved by about 11%.
Stray light absorption glass to improve high-energy laser systems’ service life becomes a meaningful method. The relationship between microstructure of the surface of absorption glass and ...laser-induced damage is crucial and still not fully understood. This paper investigates the effect of depth and width of V-shaped microstructure surface on the thermal field of absorption glass by establishing an electromagnetic heat coupling model. The graphs that represent individual conditions versus extreme temperature are achieved. The thermal distribution of the depth-to-width ratio in this microstructure which could avoid the higher temperature is mapped.
Click-through rate (CTR) prediction plays a crucial role in online services and applications, such as online shopping and advertising. The performance of CTR prediction can have a direct impact on ...user experience and the revenue of the online platforms. For CTR prediction models, self-attention-based methods have been widely applied to this field. Recent works generally adopted the Transformer architecture, where the self-attention mechanism can capture the global dependencies of the user’s historical interactions and predict the next item. Despite the effectiveness of self-attention methods in modeling sequential user behaviors, most sequential recommenders hardly exploit feature interaction techniques to extract high-order feature combinations. In this paper, we propose a Feature-Interaction-Enhanced Sequence Model (FESeq), which integrates feature interaction and the sequential recommendation model in a cascading structure. Specifically, the interacting layer in FESeq is an automatic feature engineering step for the Transformer model. Then, we add a linear time interval embedding layer and a positional embedding layer to the Transformer in the sequence-refiner layer to learn both the time intervals and the position information in the user’s sequence behaviors. We also design an attention-based sequence pooling layer that can model the relevance of the user’s historical behaviors and the target item representation through scaled bilinear attention. Our experiments show that the proposed method beats all the baselines on both public and industrial datasets.
