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We modified the morphology and distribution of copper-bearing precipitates in an Al-Mg-Si-Cu alloy and obtained ultra-high comprehensive properties through a modified thermo-mechanical treatment composed of aging and cold deformation. The precipitate evolution and atomic structure was observed by employing atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Our results proved the existence of β′′/Q′ composite precipitates in rod-like morphology after aging treatment due to the inhibition of β′′ phase formation by copper atoms. We also revealed that the peak-aged phases transformed into in-situ reverse-transformed Guinier Preston zones (GP zones) during the deformation process. By the means of modifying the precipitates, we finally simultaneously obtained ultra-high strength (424.40 MPa) as well as favorable conductive properties (52.78%IACS), both of which surpassed three mainstream standards for high strength aluminum conductor.

Reversible addition–fragmentation chain-transfer (RAFT) polymerization has been widely exploited to produce homogeneous and living polymer networks for advanced material design. In this work, we incorporate silica nanoparticles (SNPs) into a RAFT polymerization system to prepare a series of photocurable composite resins. These resins are applied to stereolithographic 3D printing to produce composite materials with enhanced mechanical properties. Relatively high loadings of SNPs (30 wt%) within the resins are achieved, allowing an increase in the 3D printed composite material tensile strength by 165% while simultaneously increasing the fracture toughness by 168%, compared with the pristine polymer materials. In addition, the inclusion of small amounts (1 wt%) of RAFT agent into the 3D printing resins also provide efficient control over thermomechanical, tensile, and fracture properties of the resulting materials. In particular, 3D printed SNP composite materials containing 30 wt% SNPs and 1 wt% RAFT show a 37% increase in elongation at break values and a 60% increase in tensile strength compared with free radical polymerization-based counterparts. The increased ductility of composite materials imparted via RAFT agent addition has not been reported and could provide a useful tool for optimizing the performance of composite materials prepared by 3D printing. Additionally, photoinduced reactivation of thiocarbonylthio groups provides access to spatially controlled post-printing functionalization of the surface of the composite materials. As such, RAFT-mediated 3D printing of composite resins is shown to be an effective strategy for developing composite materials with arbitrary combinations of well-defined mechanical properties and diverse chemical functionalities for material post-modification.

Supercapacitors possessing multiple functions other than storing energy, such as bearing mechanical loads, are a promising technology for a wide range of applications. However, achieving both energy storage efficiency and mechanical strength/stiffness requires structurally strong electrolytes and high-capacitance electrodes. Herein, we report a novel method of synthesizing a high-mass loading of MnO2 on carbon nanotube (CNT) mats to create nanocomposite electrodes of high capacitance and mechanical properties. With CNTs acting as structural reinforcement for the pseudocapacitive MnO2 matrix, the resulting nanocomposite electrodes exhibited an ultrahigh areal capacitance of 2579 mF/cm2 at a current density of 1 mA/cm2 and excellent mechanical properties. These electrodes were then used to fabricate flexible and mechanically strong structural supercapacitors by infusing with a PVA gel electrolyte and a PEGDGE solid electrolyte, respectively. The resulting flexible supercapacitors yielded a high areal capacitance of 947 mF/cm2 while the structural supercapacitors gave a high tensile modulus of 6.1 GPa. These results demonstrated that the hierarchical MnO2/CNT electrodes could provide both excellent energy storage capability and structural stiffness and strength, expanding their applications beyond mono-functional supercapacitors.

WO3–x (W-1) was used to achieve controllable photoisomerization of linear olefins without substituents under 625 nm light irradiation. Thermodynamic and kinetic isomers were obtained by regulating the carbon chain length of the olefins. Terminal olefins were converted into isomerized products, and the internal olefin mixtures present in petroleum derivatives were transformed into valuable pure olefin products. Oxygen vacancies (OVs) in W-1 altered the electronic structure of W-1 to improve its light-harvesting ability, which accounted for the high activity of olefin isomerization under light irradiation up to 625 nm. Additionally, OVs on the W-1 surface generated unsaturated W5+ sites that coordinated with olefins for the efficient adsorption and activation of olefins. Mechanistic studies reveal that the in situ formation of surface π-complexes and π-allylic W intermediates originating from the coordination of coordinated unsaturated W5+ sites and olefins ensure high photocatalytic activity and selectivity of W-1 for the photocatalytic isomerization of olefins via a radical mechanism.

Due to the poor conversion efficiency and signal-to-noise ratio (SNR) of Electromagnetic Acoustic Transducer (EMAT) testing, the defect detection sensitivity is limited, which restricts the extensive industrial applications. A finite element model for the testing process of a meander-coil EMAT was established that considers the simplified excitation and detection circuits for the EMAT. Based on this model, the effect of the connection methods (parallel or series) of the coils in the generating and receiving EMATs on their generating and receiving efficiency was investigated, and the simulation results were validated experimentally. Subsequently, the pulse compression technique with a 13-bit Barker code was used for the EMAT detection, and improvements of the SNR and range resolution were established through numerical simulation and experimental measurement. The results show that compared with the traditional EMAT design, which comprises single-layer transmitting and receiving coils, the conversion efficiency of the optimized EMAT with two excitation and receiving coils in the parallel connection can be improved by 52.8%. With the application of the Barker-coded pulse compression to detect the ultrasonic A-scan signal with no synchronous average, the SNR of the defect echo can be improved by 9.5 dB compared with the A-scan signal with 128 synchronous averages.

In this study, the carbon quantum dots, which can emit sharp red light (R-CQDs) under optical excitation, were synthesized via simple heat treatment of wine lees. The features of the photoluminescence (PL) emission from R-CQDs in solutions with different pH values and with metal ions were examined. The intensity of the PL emission from R-CQDs depends sensitively on the pH values of the solutions with the R-CQDs. Interestingly, the pH-response of the PL intensity is reversible and can be enhanced linearly in the pH value range from 4 to 12, indicating that the R-CQDs can be applied for the pH sensor. Furthermore, the quench of the PL emission from R-CQDs can be observed when adding chromium (III) ions into the solution with R-CQDs. This effect can be utilized for selective and quick detection of chromium (III) ions in solutions simply via the standard PL measurement. The interesting and important findings from this work can be applied to explore more practical applications of the CQDs prepared cheaply and easily.

To optimize the electronic structure of photocatalyst, a facile one-step approach is developed for the simultaneous realization of Zn-doping and surface oxygen vacancies (SOVs) formation on SnO2. The Zn-doped SnO2 with abundant SOVs exhibits efficient and stable performance for photocatalytic degradation of toluene under both low and high relative humidity. Experimental and theoretical calculations results show that the synergistic effects of Zn-doping and SOVs on SnO2 can considerably boost the charge transfer and separation efficiency. Utilizing the in situ DRIFTS and theoretical calculations methods, it is revealed that the benzene ring of toluene is opened at benzoic acid on the SnO2 surface and selectively at benzaldehyde on the Zn-doped SnO2 surface. This implies that Zn-doped SnO2 photocatalysts shorten the pathway of toluene degradation, and toxic intermediates can be significantly inhibited. This work could provide a promising and sustainable route for safe and efficient removal of aromatic VOCs with photocatalytic technology.

The Beishan complex, located along the Liuyuan suture in the southern Beishan, separates the Dunhuang terrane from the southern Central Asian Orogenic Belt. The ages and origins of the Beishan complex are still controversial. Based on integrated field investigation and petrological, geochronological, and geochemical work, the Beishan complex is interpreted to consist of four diachronous lithologic units with different tectonic origins. Unit I is mainly composed of meta-clastic and minor carbonate rocks; these metaclastic rocks were derived from a proximal source with dominantly intermediate–acidic magmatic materials, and were deposited in a continental arc setting during 430–280 Ma. Unit II exhibits a block-in-matrix structure with variably sized blocks of ultramafic rock, meta-gabbro, Nb-enriched pillow meta-basalt, amphibolite, calc-alkaline mylonitized diorite, marble, argillaceous slate, and quartzitic meta-chert embedded in a matrix of sheared fine-grained sandstone; this tectonic melange was emplaced during 284–267 Ma. Unit III consists of coherent quartzite, paragneiss, and biotite schist with maximum depositional ages of 1214 Ma, 817 Ma, and 1210 Ma, respectively. Unit IV was formed in a continental arc setting, and predominantly contains early Paleozoic diorite (430 Ma), TTG (455–437 Ma), and tonalite (430–429 Ma), as well as biotite–quartz schist (507–420 Ma). Consequently, we propose that the Beishan complex represents an assemblage of a continental arc and a fore-arc accretionary complex resulting from subduction of the Paleo-Asian oceanic slab. Our results indicate long-lived subduction–accretion of the Paleo-Asian Ocean and the final closure may have occurred posterior to the middle Permian.

It has been reported that convergence stalls on Bakhvalov-Shishkin mesh in the case of N − 1 ≤ e , where e is the singular perturbation parameter and N is the number of mesh intervals. To analyze these phenomena, we present uniform convergence analysis of finite element methods on Bakhvalov-type meshes, one popular kind of graded meshes closely related to Bakhvalov-Shishkin mesh, when N − 1 ≤ e . An optimal order of convergence is proved and this result is used for the improvement of Bakhvalov-Shishkin mesh. These theoretical results are verified by numerical experiments.

Simultaneous analysis of luminescence signals of multiple probes can improve the accuracy and efficiency of biosensing and bioimaging. Analysis of multiple signals at different wavelengths usually suffers from spectral overlap, possible energy transfer, and difference in detection efficiency. Herein, we reported a polymeric luminescent probe, which was composed of a phenothiazine-based fluorescent compound and a phosphorescent iridium(iii) complex. Both luminophores emitted at around 600 nm but their luminescence lifetimes are 160 times different, allowing time-resolved independent analysis. As the fluorescence was enhanced in response to oxidation by hypochlorite and the phosphorescence was sensitive toward oxygen quenching, a four-dimensional relationship between luminescence intensity, fluorescence/phosphorescence ratio, hypochlorite concentration, and oxygen content was established. In cellular imaging, time-resolved photoluminescence imaging microscopy clearly showed the independent fluorescence response toward hypochlorite and phosphorescence response toward oxygen in separated time intervals. This work opens up a new idea for the development of multiplex biosensing and bioimaging., A single-wavelength dual-emissive polymeric probe shows fluorescence enhancement toward ClO− and phosphorescence quenching toward O2, allowing simultaneously imaging cellular ClO− and O2via time-resolved photoluminescence imaging microscopy.

AgNbO3-based ceramics have been the spotlight for the lead-free dielectric capacitors due to its unique antiferroelectric feature and the ever-increasing environmental concerns. Herein, synergic modulation on the energy storage properties of AgNbO3-based ceramics was reported, in which the over-stoichiometrical introduction of only 0.10 wt% MnO2 at the atomic-scale leads to reduced leakage current, Pr and enhanced antiferroelectric stability while the SiO2 coating on the AgNbO3 particles at the micro-scale greatly inhibits the grain growth, increases the breakdown strength and the electric filed inducing the AFE-FE transitions. As a result, a large recoverable energy density up to 3.34 J/cm3 with efficiency of 60.0% was obtained in 0.10 wt% MnO2-doped AgNbO3@SiO2 ceramic, which is 2.3 times larger than that of the pristine AgNbO3. This work provides a rational approach to synergically modulate the energy storage properties.

We study linear convergence of some first-order methods such as the proximal gradient method (PGM), the proximal alternating linearized minimization (PALM) algorithm and the randomized block coordinate proximal gradient method (R-BCPGM) for minimizing the sum of a smooth convex function and a nonsmooth convex function. We introduce a new analytic framework based on the error bound/calmness/metric subregularity/bounded metric subregularity. This variational analysis perspective enables us to provide some concrete sufficient conditions for linear convergence and applicable approaches for calculating linear convergence rates of these first-order methods for a class of structured convex problems. In particular, for the LASSO, the fused LASSO and the group LASSO, these conditions are satisfied automatically, and the modulus for the calmness/metric subregularity is computable. Consequently, the linear convergence of the first-order methods for these important applications is automatically guaranteed and the convergence rates can be calculated. The new perspective enables us to improve some existing results and obtain novel results unknown in the literature. Particularly, we improve the result on the linear convergence of the PGM and PALM for the structured convex problem with a computable error bound estimation. Also for the R-BCPGM for the structured convex problem, we prove that the linear convergence is ensured when the nonsmooth part of the objective function is the group LASSO regularizer.

The formation mechanism of rockburst is complex, and its prediction has always been a difficult problem in engineering. According to the tunnel engineering data, a three-dimensional discrete element numerical model is established to analyze the initial stress characteristics of the tunnel. A neural network model for rockburst prediction is established. Uniaxial compressive strength, uniaxial tensile strength, maximum principal stress, and rock elastic energy are selected as input parameters for rockburst prediction. Training through existing data. The neural network model shows that the rockburst risk is closely related to the maximum principal stress. Based on the division of rockburst risk areas, according to different rockburst levels, the corresponding treatment methods are put forward to avoid the occurrence of rockburst disaster. Based on the field measured data and test data, combined with the existing rockburst situation, numerical simulation and neural network method are used to predict the rock burst classification, which is of great significance for the early and late construction safety of the tunnel.

Electrochemical CO2 reduction (CO2R) is a sustainable way of producing carbon-neutral fuels, yet the efficiency is limited by its sluggish kinetics and complex reaction pathways. Developing active, selective, and stable CO2R electrocatalysts is challenging and entails intelligent material structure design and tailoring. Here we show a graphdiyne/graphene (GDY/G) heterostructure as a 2D conductive scaffold to anchor monodispersed cobalt phthalocyanine (CoPc) and reduce CO2 with an appreciable activity, selectivity, and durability. Advanced characterizations, e.g., synchrotron-based X-ray absorption spectroscopy (XAS), and density functional theory (DFT) calculation disclose that the strong electronic coupling between GDY and CoPc, together with the high surface area, abundant reactive centers, and electron conductivity provided by graphene, synergistically contribute to this distinguished electrocatalytic performance. Electrochemical measurements revealed a high FECO of 96% at a partial current density of 12 mA cm-2 in a H-cell and an FECO of 97% at 100 mA cm-2 in a liquid flow cell, along with a durability over 24 h. The per-site turnover frequency of CoPc reaches 37 s-1 at -1.0 V vs RHE, outperforming most of the reported phthalocyanine- and porphyrin-based electrocatalysts. The usage of the GDY/G heterostructure as a scaffold can be further extended to other organometallic complexes beyond CoPc. Our findings lend credence to the prospect of the GDY/G hybrid contributing to the design of single-molecule dispersed CO2R catalysts for sustainable energy conversion.

Critical to the applications of pseudocapacitors is the cycling performance of electrodes. Here, we present a new carbon fibre electrode enhanced by multilayer structure of vertical graphene (VG) and manganese dioxide (MnO2) to achieve a cycling performance at a very high areal capacitance (546.3 mF/cm2) that outperforms most of the reported pseudocapacitors in the literature. Particularly, this multilayer electrode is able to retain 99.3% of its initial capacitance after 10,000 cycles at scan rate of 200 mV/s. The retention ratio is significantly higher than the state-of-art value. In addition, this electrode shows excellent rate performance (75.4% capacitance retention for current density from 1 to 10 mA/cm2). This exceptionally high stability at high capacitance and rate performance originates from the multilayer electrode’s effectiveness in self-replenishing the degraded MnO2 in the outer layer. The microcracks and micro holes induced in the VG layer by electrical charge/discharge cycling enable the inner layer MnO2 to progressively participate in the redox reaction. Results from energy dispersive spectroscopy, X-ray photoelectron, and Raman spectroscopy confirm the self-replenishing mechanism responsible for the exceptionally stable performance. The new multilayer electrode designed herein provides a new route for improving the cycling performance of pseudocapacitors.

To obtain an A356 aluminum alloy casting with a uniform structure and no internal shrinkage defects, ProCAST software is used to set different filling and solidification process parameters for an A356 aluminum alloy casting with large wall thickness differences, And multiple simulations are conducted to obtain optimized casting process; then, based on the process, the microstructure of the thickest and thinnest part of the casting are simulated. The size, morphology, and distribution of the simulated microstructure of the thinnest part and the thickest part of the casting are very similar. The simulated microstructure is similar to that of the actual casting. This shows that castings with uniform structure and no internal shrinkage defects can be obtained through the optimized casting process .

Transceiving ultra-weak sound typically relies on signal pre-amplification at the transmitting end via active electro-acoustic devices, which inherently perturbs the environment in the form of noise that inevitably leads to information leakage. Here we demonstrate a passive remote-whispering metamaterial (RWM) enabling weak airborne sound at audible frequencies to reach unprecedented signal enhancement without altering the detected ambient soundscape, which is based on the extraordinary scattering properties of a metamaterial formed by a pair of self-resonating subwavelength Mie meta-cavities, constituting the acoustic analogy of Förster resonance energy transfer. We demonstrate efficient non-radiative sound transfer over distances hundreds times longer than the radius of the meta-cavities, which enables the RWM to recover weak sound signals completely overwhelmed by strong noise with enhanced signal-to-noise ratio from −3 dB below the detection limit of 0 dB in free space to 17.7 dB., Typically, sending sound from transmitter to receiver requires pre-amplification and disturbs the surrounding sound environment. Here, the authors present a metamaterial designed to enable transmission of weak sound that can be recovered even in the presence of strong noise

Predictive modeling for toxicity can help reduce risks in a range of applications and potentially serve as the basis for regulatory decisions. However, the utility of these predictions can be limited if the associated uncertainty is not adequately quantified. With recent studies showing great promise for deep learning-based models also for toxicity predictions, we investigate the combination of deep learning-based predictors with the conformal prediction framework to generate highly predictive models with well-defined uncertainties. We use a range of deep feedforward neural networks and graph neural networks in a conformal prediction setting and evaluate their performance on data from the Tox21 challenge. We also compare the results from the conformal predictors to those of the underlying machine learning models. The results indicate that highly predictive models can be obtained that result in very efficient conformal predictors even at high confidence levels. Taken together, our results highlight the utility of conformal predictors as a convenient way to deliver toxicity predictions with confidence, adding both statistical guarantees on the model performance as well as better predictions of the minority class compared to the underlying models.

30SiMn2MoVA is a high-strength alloy steel used for barrels. Cold radial forging can greatly improve the performance of axles, barrels and other shaft parts. However, residual stresses will greatly affect the dimensional stability and service life of the products. This work focused on the effects of different annealing temperatures on the residual stress, microhardness, dislocation density, grain boundary and grain size of radial forged tubes. The results show that the residual stresses are gradually eliminated with the deformed grains transform into equiaxed and the reduction in dislocation density. The residual stress relaxation caused by the creep process conforms to the Zener-Wert-Avrami equation. As the dislocation density and low-angle grain boundary decrease, the microhardness also decreases gradually. The best annealing temperature for radial forged 30SiMn2MoVA high-strength steel tube is 500 °C. After annealing at 500 °C, the microhardness decreases by 5%, the axial and hoop residual stress on the outer surface are close to 0 MPa, and the residual stress near the inner surface are less than 200 MPa. When the annealing temperature is higher than 500 °C, there is no significant change in residual stress relaxation rate. Nevertheless, the grain size and the low angle boundary decreased significantly. Partial recrystallization occurred, and the microhardness decreased by more than 10%.

Carbonaceous slate is heterogeneous and anisotropic, which has a great influence on the stability of tunnel. In this paper, by means of laboratory test, field measurement, and numerical simulation, the surrounding rock stability and plastic zone distribution characteristics of the carbonaceous slate tunnel at different intersection angles are analyzed. First, combined with the Haibaluo tunnel project, Brazilian splitting and uniaxial compression tests of jointed carbonaceous slate are performed. The test results show that the tensile strength of carbonaceous slate is related to joint dip angle. When the joint angle is 0°, the tensile strength is the largest and decreases with the increase of the joint angle. The uniaxial strength of rock decreases first and then increases. Based on the discrete fracture network (DFN) technology, a calculation model is established. The calculation results show that the maximum displacement is 0.45 m, when the dip angle of the surrounding rock joint is 45°. The field measurement also shows that the dip angle of the surrounding rock joint has an important influence on the distribution of the plastic zone. When the joint dip angle is 45°, the plastic zone develops most strongly.

All biological processes arise through the coordinated actions of biochemical pathways. How such functional diversity is achieved by a finite cast of molecular players remains a central mystery in biology. Spatial compartmentation-the idea that biochemical activities are organized around discrete spatial domains within cells-was first proposed nearly 40 years ago and has become firmly rooted in our understanding of how biochemical pathways are regulated to ensure specificity. However, directly interrogating spatial compartmentation and its mechanistic origins has only really become possible in the last 20 or so years, following technological advances such as the development of genetically encoded fluorescent biosensors. These powerful molecular tools permit a direct, real-time visualization of dynamic biochemical processes in native biological contexts, and they are essential for probing the spatial regulation of biochemical activities. In this Account, we review our lab's efforts in developing and using biosensors to map the spatial compartmentation of intracellular signaling pathways and illuminate key mechanisms that establish the boundaries of an intricate biochemical activity architecture. We first discuss the role of regulatory fences, wherein the dynamic activation and deactivation of diffusible messengers produce diverse signaling compartments. For example, we used biosensors for the Ca2+ effector calmodulin and its downstream target calcineurin to reveal a spatial gradient of calmodulin that controls the temporal dynamics of calcineurin signaling. Our studies using cyclic adenosine monophosphate (cAMP) biosensors have similarly elucidated fenced cAMP domains generated by competing production and degradation pathways, ranging in size from cell-spanning gradients to nanoscale hotspots. Second, we describe the role played by intracellular membranes in creating unique signaling platforms with distinctive pathway regulation, as revealed through studies using subcellularly targeted fluorescent biosensors. Using biosensors to visualize subcellular extracellular response kinase (ERK) pathway activity, for example, led us to discover a local signaling circuit that mediates distinct plasma membrane ERK dynamics versus global ERK signaling. Similarly, our work developing biosensors to monitor the subcellular mechanistic target of rapamycin complex 1 (mTORC1) signaling allowed us to not only clarify the presence of mTORC1 activity in the nucleus but also identify a novel mechanism governing the activation of mTORC1 in this location. Finally, we detail how molecular assemblies enable the precise spatial tuning of biochemical activity, through investigations enabled by cutting-edge advances in biosensor design. We recently identified liquid-liquid phase separation as a major factor in cAMP compartmentation aided by a new strategy for targeting biosensors to endogenously expressed proteins via genome editing, for instance, and have also been able to directly visualize nanometer-scale protein kinase signalosomes using an entirely new class of biosensors specifically developed for the dynamic super-resolution imaging of live-cell biochemical activities. Our work provides key insights into the molecular logic of spatially regulated signaling and lays the foundation for a broader exploration of biochemical activity architectures across multiple spatial scales.

In this paper, we conduct a comprehensive investigation on the thermal transport in one-dimensional (1D) van der Waals (vdW) heterostructures by using non-equilibrium molecular dynamics simulations. As for the considered 1D vdW heterostructures having a base of (40,40) carbon nanotube (CNT), we find that the boron nitride nanotube (BNNT) coating can increase the thermal conductance of inner CNT base by 36%, while the molybdenum disulfide nanotube (MSNT) coating can reduce the thermal conductance by 47%. The different effects of nanotube coatings on the thermal transport behaviors of 1D vdW heterostructures are explained by the competition mechanism between the improved heat flux and the increased temperature gradient in 1D vdW heterostructures. The thermal transport in 1D vdW heterostructures containing three layers is also investigated. It is found that the coaxial BNNT-MSNT coating can significantly reduce the thermal conductance of inner CNT base by 61%, which is even larger than the influence of an individual MSNT coating. This work not only provides molecular insights into the heat transport behaviors of 1D vdW heterostructures but also provides guidance for the design of 1D vdW heterostructures with desired thermal properties.

Summary Two-dimensional (2D) graphdiyne (GDY) is a promising floating-gate material for flexible optoelectronic flash memory owing to its fascinating electrical and optical properties. However, research in GDY-based flash memory is still in its infancy owing to the huge challenge in the synthesis of large-area and ultrathin GDY films with high quality and uniformity. Here, an electric double-layer-confined strategy is proposed to synthesize a wafer-scale GDY film with thickness of 1 nm. Then, a two-terminal top-floating-gated optoelectronic memory with multibit storage capability is investigated using GDY as a photoresponsive top-floating gate. Benefiting from the excellent charge storage capability and high photoresponse of GDY, this device exhibits over 256 distinct storage levels (8 bits) with signal-to-noise ratios larger than 100. Moreover, the fully 2D material and two-terminal architecture endows the device with robust bending stability for over 1,000 bending circles, paving the way to develop wearable electronics.

Microwave absorbing metasurfaces with optical transparency are essentially useful in electromagnetic compatibility, stealth, or camouflage while keeping continuous optical observation or communication. Although significant efforts have been devoted on expanding the bandwidths of optically transparent absorbing metasurfaces, dynamic control of microwave absorption in such metasurfaces remains a challenge. In this paper, we experimentally propose a metasurface made of patterned graphene sandwich structures, showing unprecedented wave control, excellent optical transparency and outstanding flexibility. Both the simulated and measured results demonstrate that the tunable absorption with dual, single and broad band are realized by applying bias voltage to graphene layers. In particular, the as-designed metasurface shows a strong microwave absorption of 90 % covering a wide frequency band of 7–18 GHz due to the electric and magnetic resonances caused by the patterned graphene layer, as well as the multiple reflection mechanism. We speculate that such a metasurface with optical transparency and tunable microwave absorption has potential applications in stealth technology and photovoltaic solar cells.

The tuff layer steadily distributed in the western Yangtze Craton is a regional marker for the Early–Middle Triassic (Olenekian–Anisian) boundary. Integrated studies of whole-rock geochemistry and zircon geochronology reveal that the parental magma of the tuff is of felsic composition, generated via volcanic eruptions in the continental arc setting along the southwestern margin of the Yangtze Craton at ~247 Ma. The syn-depositional zircons in the tuff layers and in the coeval igneous rocks exhibit uniform negative eHf(t) values of approximately −20 to −6, indicating the significant input of crustal materials. Massive crustal assimilation implies a large-scale remelting of the pre-existing continental crust, triggered by the intensive arc–continental collision during that time. This intensive collisional tectonomagmatic event is an important signal for the closing of the eastern Paleo-Tethys branch and points to the initial collision of the Indochina Block and the Yangtze Craton. Xenocrystic zircons in the Precambrian-age offer insight into the early evolution of the southwestern Yangtze Craton, which shows episodic crustal growth and reworking of ~2.9–2.2 Ga, crustal reworking of ~1.9–1.7 Ga, rifting-related tectonomagmatism of ~1.6–1.4 Ga, and crustal growth of ~1.1–0.8 Ga. The older crystallization ages (3.4–2.5 Ga), lower initial 176Hf/177Hf values (0.2805–0.2813), negative eHf(t) values (−15.7 to −1.6), and two-stage Hf model ages (3.9–2.8 Ga) of zircons further suggest that an unexposed Archean basement exists beneath the southwestern Yangtze Craton. Significant contributions of mantle-derived materials occur at ~1.3–1.0 Ga, implying that the southwestern Yangtze Craton may not be involved in the Grenvillian-aged continental–continental collision orogeny. Comparable age spectrums and Hf isotopic data suggest that the Paleoproterozoic igneous rocks are a non-negligible provenance for Proterozoic metasedimentary in the Kangdian region.

Funding Information: This work was supported by the National Natural Science Foundation of China (52025023, 51991342, 52021006, 51722204, 51972041, 51972042, 51672007, 11974023, 12025407 and 11934003), the National Key R&D Program of China (2016YFA0300903 and 2016YFA0300804), Beijing Natural Science Foundation (JQ19004), Beijing Excellent Talents Training Support (2017000026833ZK11), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB33000000), Beijing Municipal Science & Technology Commission (Z191100007219005), Beijing Graphene Innovation Program (Z181100004818003), Key-Area Research and Development Program of GuangDong Province (2020B010189001, 2019B010931001 and 2018B030327001), the Science, Technology and Innovation Commission of Shenzhen Municipality (KYTDPT20181011104202253), Bureau of Industry and Information Technology of Shenzhen (Graphene platform 201901161512), The Pearl River Talent Recruitment Program of Guangdong Province (2019ZT08C321), National Equipment Program of China (ZDYZ2015-1) and the China Postdoctoral Science Foundation (2020M680177). Publisher Copyright: © 2021, The Author(s), under exclusive licence to Springer Nature Limited. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Colloidal quantum dots are promising photoactive materials that enable plentiful photonic and optoelectronic applications ranging from lasers, displays and photodetectors to solar cells1–9. However, these applications mainly utilize the linear optical properties of quantum dots, and their great potential in the broad nonlinear optical regime is still waiting for full exploration10–12. Here, we demonstrate that a simple coating of a sub-200-nm-thick quantum dot film on two-dimensional materials can significantly enhance their nonlinear optical responses (second, third and fourth harmonic generation) by more than three orders of magnitude. Systematic experimental results indicate that this enhancement is driven by a non-trivial mechanism of multiphoton-excitation resonance energy transfer, where the quantum dots directly deliver their strongly absorbed multiphoton energy to the adjacent two-dimensional materials by a remote dipole–dipole coupling. Our findings could expand the applications of quantum dots in many exciting areas beyond linear optics, such as nonlinear optical signal processing, multiphoton imaging and ultracompact nonlinear optical elements.

The development of rechargeable lithium-ion batteries (LIBs) is being driven by the ever-increasing demand for high energy density and excellent rate performance. Charge transfer kinetics and polarization theory, considered as basic principles for charge regulation in the LIBs, indicate that the rapid transfer of both electrons and ions is vital to the electrochemical reaction process. Graphene, a promising candidate for charge regulation in high-performance LIBs, has received extensive investigations due to its excellent carrier mobility, large specific surface area and structure tunability, etc. Recent progresses on the structural design and interfacial modification of graphene to regulate the charge transport in LIBs have been summarized. Besides, the structure-performance relationships between the structure of the graphene and its dedicated applications for LIBs have also been clarified in detail. Taking graphene as a typical example to explore the mechanism of charge regulation will outline ways to further understand and improve carbon-based nanomaterials towards the next generation of electrochemical energy storage devices.

We not only firstly applied the theory of hub-and-spoke network to the field of integrated transportation network planning, but also combined our proposed method with Sichuan-Tibet railway, one of super large projects in China, to discuss the optimization and the layout of hub-and-spoke integrated transportation network along the Sichuan-Tibet railway after it is put into operation in the future and put forward some directional policy recommendations. In our study, we have made clear the topological structure of the multi hub and single allocation hybrid hub-and-spoke integrated transportation network in the passenger transportation corridors, established the integer programming model aiming at the minimum generalized travel cost in the network, and we designed the simulated annealing algorithm to solve this problem. In the empirical study, we find that if 5 nodes are selected as hub nodes in hub-and-spoke integrated transportation network, the generalized cost of network travel will be minimized and these specific location of 5 hub nodes can be determined by the selecting principle of hub nodes location, which we proposed in our study. The simulated annealing algorithm can help us to find the connection relationship between nodes. Then we can achieve three types of hub-and-spoke integrated transportation network layout patterns with railway, highway and aviation as the hub nodes. Though further comparative analysis, we find that it is more feasible to choose the integrated transportation network with railway nodes as the hub in transportation organization. Based on this understanding, we put forward policy recommendations on transportation organization to support high-quality planning and operation of integrated transportation network to Sichuan Tibet region in China in the future.

The microscopic structure of a macroscopic material assembled from a nanoscale determines its performance in practical functional applications. The rapid, effective, and in situ characterization of...

The addition of carbon additives to the catalytic layers (CLs) with low-Pt loadings significantly improves the cell performance of proton exchange membrane fuel cells. However, the structure-activity relationship between the different dimensional carbon materials in CLs and the cell performance is still unknown. In the present work, three different dimensional carbon materials have been added into the cathode CLs with low Pt loading. The addition of one-dimensional carbon nanotubes and zero-dimensional XC-72R significantly enhanced the power density of the fuel cell because of the improved Pt dispersion and porous structures of the CL. This resulted in enhanced gas transfer and water removal accessibility. Nevertheless, the tortuous transfer path of gas and water after the presence of graphene nanosheet in the CL results in increased mass transfer resistance, although it reduces the charge transfer of the CL due to the improved catalyst utilization at low current density regions of polarization curves.

There is increasing evidence for graphene associated plant growth promotion, however, the chronic effects of soil-applied graphene remain largely unexplored. The present study investigated the morphological, physiological and biochemical responses of graphene oxide (GO) on Aloe vera L. over the concentration range of 0–100 mg/L for four months. Our results demonstrated that GO, with the best efficiency at 50 mg/L, could enhance the photosynthetic capacity of leaves, increase the yield and morphological characters of root and leaf, improve the nutrient (protein and amino acid) contents of leaf, without reducing the content of the main bioactive compound aloin. Compared with leaves, the effect of GO on root growth was more obvious. Although the electrolyte leakage and MDA content were raised at high concentrations, GO treatment did not increase the root antioxidant enzymes activity or decrease the root vigor, which excluding typical stress response. Furthermore, injection experiments showed that the GO in vivo did not change the plant growth state obviously. Taken together, our study revealed the role of GO in promoting Aloe vera growth by stimulating root growth and photosynthesis, which would provide theory basis for GO application in agriculture and forestry.

The fluorescent carbon quantum dots (FCQDs) are promising for wide applications especially in the field of optoelectronic materials and devices. For these applications, it is essential to examine the optoelectronic properties of FCQDs not only in a solution but also in the form of dry particles. Here we study the optoelectronic properties of dry FCQDs by using terahertz (THz) time-domain spectroscopy (TDS). The THz response of dry FCQDs, which can emit blue (B-CQDs) and red (R-CQDs) lights in solutions under optical excitation, has been measured in temperature range from 80 to 280 K. We find that R-CQDs behaves like an optical insulator in 0.2–1.2 THz range, while B-CQDs experiences insulator-to-semiconductor transition with increasing THz frequency and temperature. The optical conductance and the key sample parameters of B-CQDs are determined. This is the first research work in applying the THz TDS to study the dry CQDs. The findings from this study can be helpful in gaining an in-depth understanding of the physical properties of dry FCQDs.

The dehydrogenation and isomerization of glycerol to produce lactic acid is an important way to realize the effective utilization of biodiesel by-products. Currently, precious metal catalysts have been widely used in the preparation of lactic acid from glycerol. In this paper, Cu-supported zeolitic imidazolate framework (ZIF-8) crystals of different loadings were synthesized by the reaction of zinc nitrate, copper nitrate and 2-aminobenzophenone at room temperature, and were applied to the reaction of glycerol to lactic acid. Characterizations including XRD, XPS, SEM, TEM, BET, FT-IR, UV–vis DRS, CO2-TPD and TG were carried out to evaluate the morphology and properties of the catalysts. The results showed that the lattice structure of body centered cubic of the materials was successfully formed, and nano-copper was distributed uniformly on the supports, which provided abundant active alkaline sites. In addition, the catalytic reactions achieved good results under optimum copper loading and reaction conditions, which the glycerol conversion and lactic acid yield can reach 97.5% and 84.2%, respectively.

Mixed ion–electron conductors have a wide range of important applications in devices relying on mixed ion–electron transport, mainly including conducting polymer composites and ceramics. Herein, we...

Nanopore-based detection techniques, with a wide range of transport properties, exhibit impressive selectivity and sensitivity for analytes. To expand the application of nanoporous sensors, real-time and fast detection of targets, all within a portable device, is highly desired for nanopore-based sensors. In addition, to improve the accuracy of the output signal, more appropriate readout methods also need to be explored. In this manuscript, we describe a nanopore-based electrode, regarded as NAC-P6-PC@AuE, prepared by coupling a pillararene-based nanoporous membrane with an electrochemical impedance measurement method. The fabricated device is demonstrated by exposing pillararene-based receptors to trace amounts of pesticide molecules. NAC-P6-PC@AuE devices exhibit distinguished selectivity to quinotrione, as well as the ability to quantify quinotrione with a limit of quantitation (LOQ) of 10 nM. The mechanism that allows sensing was verified using finite-element simulations and may be explained as host-guest-induced surface charge shielding, which influences the electrochemical response of probe molecules. The applications of this nanopore-based electrode may be extended toward other target molecules by decorating the nanopore surfaces with specifically chosen receptors.

In this paper, we use the analytic methods, the properties of the sixth-order characters, and the classical Gauss sums to study the computational problems of a certain special sixth residues’ modulo p and give two exact calculating formulas for them.

The history and mechanisms of dust storms in northern China remain unclear owing to the paucity of reliable long-term, high-resolution geological records. In this study, we reconstructed the dust storm history of the last ~500 years in northern China, based on sedimentary coarse fraction (>63 µm) of a well-dated core from Lake Daihai, Inner Mongolia. The high-resolution data reveal three intervals of frequent dust storms: AD 1520–1580, AD 1610–1720, and AD 1870–2000. The dust storm events in the Lake Daihai area were broadly synchronous with those inferred from other historical or geological records and generally occurred during cold intervals. Changes in the intensity of Siberian High and the westerlies modulated by temperature variations are the likely major factors controlling dust storm dynamics. An interesting feature is that although the intensities of dust storms have been systematically increased during the recent warming period, a clear decreasing trend within this period is evident. The recent increase in average dust storm intensity may be ascribed to an increase in particle supply resulting from a rapid increase in human activity, whereas the weakening trend was likely caused by decreases in average wind speed resulting from the recent global warming.

In-situ growth of high-density single-walled carbon nanotube (SWNT) arrays with homogeneity is highly desirable for integrated circuits. However, disastrous migration and aggregation of catalyst nanoparticles on substrate has greatly limited the area of as-grown SWNT arrays. Herein, we develop a magnesium-assisted catalyst anchoring strategy to restrain catalyst nanoparticles sintering on substrate. Magnesium modification ameliorates sapphire surface by high temperature solid reaction and thus provides a stronger metal-support interaction (SMSI). Hereby, we realize the direct growth of high-density SWNT arrays that fully cover an entire 10×10 mm2 substrate with the local highest density of ≈110 tubes μm-1 using iron as catalyst. This strategy was also proven universal when employing solid carbide catalysts.

Elucidating the reaction mechanism of hydrazine oxidation reaction (HzOR) over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR. In present work, isolated first-row transition metal atoms have been coordinated with N atoms on the graphite layers of carbon nanotubes via a M-N4-C configuration (MSA/CNT, M=Fe, Co and Ni). The HzOR over the three single atom catalysts follows a predominant 4-electron reaction pathway to emit N2 and a negligible 1-electron pathway to emit trace of NH3, while their electrocatalytic activity for HzOR is dominated by the absorption energy of N2H4 on them. Furthermore, FeSA/CNT reverses the passivation effect on Fe/C and shows superior performance than CoSA/CNT and NiSA/CNT with a recorded high mass activity for HzOR due to the higher electronic charge of Fe over Co and Ni in the M-N4-C configuration and the lowest absorption energy of N2H4 on FeSA/CNT among the three MSA/CNT catalysts.

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, but an effective targeted therapy has not been well-established so far. Considering the lack of effective targets, where do we go next in the current TNBC drug development? A promising intervention for TNBC might lie in de novo small-molecule drugs that precisely target different molecular characteristics of TNBC. However, an ideal single-target drug discovery still faces a huge challenge. Alternatively, other new emerging strategies, such as dual-target drug, drug repurposing, and combination strategies, may provide new insight into the improvement of TNBC therapeutics. In this review, we focus on summarizing the current situation of a series of candidate small-molecule drugs in TNBC therapy, including single-target drugs, dual-target drugs, as well as drug repurposing and combination strategies that will together shed new light on the future directions targeting TNBC vulnerabilities with small-molecule drugs for future therapeutic purposes.

China is the largest emitter of polycyclic aromatic hydrocarbons (PAHs) in the world. Because of their negative influences on human health, the characteristics and potential driving forces of PAH emissions should be evaluated to establish effective mitigation strategies for different economic sectors. This study is the first to quantify the embodied and enabled PAH emissions of 108 sectors in China in 2002, 2007, 2012, and 2017. The results show that the total sectoral emissions increased by 92% (from 28.0 to 53.7 kt) from 2002 to 2012 and decreased to 53.0 kt in 2017. The eight aggregated sectors had different characteristics according to their production-, consumption-, and income-based emissions. Both the embodied and enabled emission flows increased (from 13.8 to 29.2 kt and from 11.3 to 20.5 kt, respectively) with time. The influences of the major final demands and primary inputs reversed from increasing to decreasing emissions over time. In particular, the primary input structure had a stronger impact on decreasing emissions than the final demand structure. The results revealed that different mitigation policies should be applied to different sectors and that adjusting primary input behaviors might be a relatively efficient method to reduce PAH emissions.

Dynamic regulation has been widely applied to optimize metabolic flux distribution. However, compared with prokaryotes, quorum sensing-mediated pathway control is still very limited in Saccharomyces cerevisiae. In this study, we designed quorum sensing-regulated protein degradation circuits for dynamic metabolic pathway control in S. cerevisiae. The synthetic quorum sensing circuits were developed by integration of a plant hormone cytokinin system with the endogenous yeast Ypd1-Skn7 signal transduction pathway and the positive feedback circuits were optimized by promoter engineering. We then constructed an auxin-inducible protein degradation system and used quorum sensing circuits to regulate auxin synthesis to achieve dynamic control of protein degradation. As a demonstration, the circuits were applied to control Erg9 degradation to produce α-farnesene and the titer of α-farnesene increased by 80%. The population-regulated protein degradation system developed here extends dynamic regulation to the protein level in S. cerevisiae and is a promising approach for metabolic pathway control.

Rice false smut caused by Ustilaginoidea virens is one of the widespread rice diseases across the globe in recent years, however, we know little about its molecular mechanism of infection. The cAMP signaling pathway functions directly in the development and formation of infectious structures to regulate the infection process in many pathogenic fungi. In order to investigate the role of the cAMP signaling pathway in U. virens, UvCap1, a cyclase-associated-protein homologous to Saccharomyces cerevisiae Srv2 was identified. Three targeted deletion mutants of the UvCAP1 gene were obtained with gene replacement strategy assisted with CRISPR-Cas9 system. The UvCAP1 deletion mutants showed defects in mycelial growth and conidial production. Inoculation experiments demonstrated that ΔUvcap1 exhibited defects in pathogenicity. Compared with the wild-type strain, ΔUvcap1 showed decreased tolerance to sorbitol and H2O2, and increased tolerance to NaCl, CFW and SDS, and the intracellular cAMP level was significantly reduced in ΔUvcap1. Yeast two-hybrid assay identified the interactions of UvCap1 with UvAc1 (adenylase cyclase), two Ras proteins (UvRas1 and UvRas2) and UvSte50. Taken together, as a component of cAMP signaling pathway, UvCap1 plays important roles in the development and pathogenicity of U. virens.

Heteropoly acids have been employed to increase the proton conductivity of phosphoric acid (PA) doped polymer membranes for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). In this work, we develop a new composite membrane based on phosphotungstic acid (PWA) doped polyethersulfone-polyvinylpyrrolidone (PES-PVP) matrix, forming PWA/PES-PVP composite membrane for HT-PEMFCs. The homogeneous distribution of PWA on the PES-PVP membrane enhances its mechanical strength. In addition, there is a strong interaction between PWA and PA that is confirmed experimentally by the attenuated total reflectance Fourier Transform Infrared spectroscopy and semi-empirical quantum mechanics calculation. This enhances not only the PA uptake but also the proton conductivity of the PWA/PES-PVP composite membrane. 1H nuclear magnetic resonance spectroscopy results elucidate that the high proton conductivity of the PA doped PWA/PES-PVP membranes is due to their higher proton content and mobility compared to the pristine PA doped PES-PVP membrane. The best results are observed on the PES-PVP composite membrane with addition of 5 wt% PWA, reaching proton conductivity of 1.44 × 10−1 S cm−1 and a peak power density of 416 mW cm−2 at 160 °C and anhydrous conditions. PWA additives increase the proton conductivity and cell performance, demonstrating significantly positive effects on the acid-base composite membranes for high temperature polymer electrolyte membrane fuel cell applications.

To investigate the rock particle breakage behavior subject to impact load, a series of split Hopkinson pressure bar (SHPB) tests were conducted on selected Nishan rock and Shoushan rock particles within gravel size range at different strain rates. Both rock particles exhibit a typical strain softening macrobehavior and their dynamic peak strengths increase with strain rate. A dynamic increasing factor (DIF) is used to describe this strain rate effect. Based on the SHPB test, a constitutive model is proposed for the two types of rock particles to describe their dynamic stress–strain behavior considering strain rate effect and damaging effect. Grain size distribution of fractured rock particles was analyzed, which reflected the fragmentation characteristics quantitatively. A fractal theory was used to describe the fragmentation characteristics and dynamic strength of both types of rock particles. Dynamic strength was found to vary differently with fractal dimension for Nishan rock and Shoushan rock.

Graphene has extensive application in various prospects due to its good stability, high conductivity, and large specific surface area. However, the dispersion of graphene in solvents can significan...

The application of the Assembly–Disassembly–Organization–Reassembly (ADOR) protocol to the synthesis of germanosilicate zeolites has become a major milestone in material design by enabling the prep...

The effect of cucurbit[7]uril (CB[7]) on fluorescence properties and biocompatibility of the bis-viologen biphenyl molecule (BPV22+) was investigated by using 1H NMR spectroscopy, fluorescence emission titration, and in vitro cytotoxicity experiments. CB[7] can be combined with BPV22+ in a stoichiometric ratio of 1:1 and 2:1. After the formation of host-guest complex, the fluorescence emission intensity of BPV22+ increased significantly, and the emission spectrum blue shifted. Meanwhile, the host-guest complexes showed better biocompatibility than BPV22+ in cell cytotoxicity studies. Results of this paper lay a foundation for the development of host-guest type of fluorescent probes, biological imaging and so forth.

Following the implementation of the strictest clean air policies to date in Beijing, the physicochemical characteristics and sources of PM2.5 have changed over the past few years. To improve pollution reduction policies and subsequent air quality further, it is necessary to explore the changes in PM2.5 over time. In this study, over one year (2017–2018) field study based on filter sampling (TH-150C; Wuhan Tianhong, China) was conducted in Fengtai District, Beijing, revealed that the annual average PM2.5 concentration (64.8 ± 43.1 μg/m3) was significantly lower than in previous years and the highest PM2.5 concentration occurred in spring (84.4 ± 59.9 μg/m3). Secondary nitrate was the largest source and accounted for 25.7% of the measured PM2.5. Vehicular emission, the second largest source (17.6%), deserves more attention when considering the increase in the number of motor vehicles and its contribution to gaseous pollutants. In addition, the contribution from coal combustion to PM2.5 decreased significantly. During weekends, the contribution from EC and NO3− increased whereas the contributions from SO42−, OM, and trace elements decreased, compared with weekdays. During the period of residential heating, PM2.5 mass decreased by 23.1%, compared with non-heating period, while the contributions from coal combustion and vehicular emission, and related species increased. With the aggravation of pollution, the contribution of vehicular emission and secondary sulfate increased and then decreased, while the contribution of NO3− and secondary nitrate continued to increase, and accounted for 34.0% and 57.5% of the PM2.5 during the heavily polluted days, respectively.

Achieving moldable energy storage devices will make it possible to power wearable electronics by adapting to body contours for wear comfort. Herein, we present a new approach to create hierarchically structured electrodes that enable supercapacitors to retain their capacity under mechanical deformation. The electrodes are made by first growing vertical graphene nanosheets (VGNs) and then depositing manganese oxide (MnO2) on ductile nickel wires. Two such electrodes are made into a moldable supercapacitor using a solid-state electrolyte containing carboxymethylcellulose and sodium sulfate. This foldable supercapacitor achieves a high areal capacitance up to 56 mF cm−2, areal energy density of 7.7 μWh cm−2, and areal power density of 5 mWh cm−2. These exceptional properties originate from the synergy between VGNs and MnO2, where the highly porous VGNs serve two critical functions: a mechanically robust platform of large surface area allowing high mass loading deposition of pseudocapacitive MnO2 and an interconnected conductive network for efficient electron/ion transport. Fiber-shaped supercapacitors made from these electrodes can be molded into different shapes by bending and twisting with little performance loss. The promising results presented in this study provide a new route for fabricating high-performance moldable energy storage devices for wearable electronics and wireless electronic skins.