Search

Co/SiC catalysts have exhibited excellent performance in Fischer-Tropsch synthesis reaction. However, few research focuses on investigating the effect of SiC supports surface properties of on catalyst performance. In this study, ZrO2was utilized to modify the SiC surface, leading to the preparation of a series of Co-ZrO2/SiC catalysts. The physicochemical properties of the catalyst were comprehensively analyzed by using N2adsorption, XRD, H2-TPR, XPS analyses. Catalytic performance was evaluated using a fixed bed reactor, shedding light on the effect of ZrO2modified SiC support on cobalt-based Fischer-Tropsch synthesis catalysts. The results indicated that ZrO2surface modification on SiC resulted in an enhanced reduction degree of Co/SiC catalysts. Additionally, ZrO2exhibited strong interaction with the amorphous phase on the SiC surface, thereby weakening the interaction between Co and the amorphous phase. This led to an increase in the electron density of cobalt species, consequently improving the selectivity of Co/SiC catalysts towards long-chain hydrocarbons.

Some studies have shown that the incidence of type 2 diabetes increases after a diagnosis of COVID-19, although the evidence is not conclusive. However, the effects of the COVID-19 vaccine on this association, or the effect on other diabetes subtypes, are not clear. We aimed to investigate the association between COVID-19 and incidence of type 2, type 1, gestational and non-specific diabetes, and the effect of COVID- 19 vaccination, up to 52 weeks after diagnosis.

In this paper, we explore a novel online learning setting, where the online learners are presented with “doubly-streaming” data. Namely, the data instances constantly streaming in are described by feature spaces that over-time evolve, with new features emerging and old features fading away. The main challenge of this problem lies in the fact that the newly emerging features are described by very few samples, resulting in weak learners that tend to make error predictions. A seemingly plausible idea to overcome the challenge is to establish a relationship between the old and new feature spaces, so that an online learner can leverage the knowledge learned from the old features to better the learning performance on the new features. Unfortunately, this idea does not scale up to high-dimensional feature spaces that entail very complex feature interplay. Specifically. a tradeoff between onlineness, which biases shallow learners, and expressiveness, which requires deep models, is inevitable. Motivated by this, we propose a novel paradigm, named Online Learning Deep models from Data of Double Streams (OLD3S), where a shared latent subspace is discovered to summarize information from the old and new feature spaces, building an intermediate feature mapping relationship. A key trait of OLD3S is to treat the model capacityas a learnable semantics, aiming to yield optimal model depth and parameters jointly in accordance with the complexity and non-linearity of the input data streams in an online fashion. To ablate its efficacy and applicability, two variants of OLD3S are proposed namely, OLD-Linear that learns the relationship by a linear function; and OLD-FD learns that two consecutive feature spaces pre-and-post evolution with fixed deep depth. Besides, instead of re-starting the entire learning process from scratch, OLD3S learns multiple newly emerging feature spaces in a lifelong manner, retaining the knowledge from the learned and vanished feature space to enjoy a jump-start of the new features’ learning process. Both theoretical analysis and empirical studies substantiate the viability and effectiveness of our proposed approach.

Multi-wavelength imaging is crucial for gaining detailed insights into the multi-depth or multi-wavelength information present in the scenes. However, conventional methods often have limitations, like costly and bulky components restricted to specific wavelength ranges. Here, we introduce an imaging technique named “stochastic photoluminescence and compressed encoding,” or SPACE. SPACE leverages randomly arrayed lanthanide transducers as photonic encoders to capture various excitation wavelengths in a single image, recorded by a charge-coupled device. This approach enables the reconstruction of multiple scenes from this encoded image across four wavelength channels: X-rays (0.089 nm), ultraviolet (375 nm), and two near-infrared bands (808 and 1,532 nm), with the ability to expand to more channels through multi-layer encoders. SPACE enables multi-channel imaging for depth visualization and multi-spectral X-ray analysis, offering broad multi-spectral sensitivity and on-chip compatibility. This makes it a versatile tool for applications in materials characterization, bioimaging, remote sensing, and astronomy.

The catalytic epoxidation of a-olefin with long carbon chains has always been a challenge. Traditional homogeneous or heterogeneous catalysts showed poor performance toward the reaction. In this paper, layered organic–inorganic catalysts were prepared by the reaction of phosphotungstic acid and a Gemini quaternary ammonium salt, which could convert long a-olefin to epoxide with a selectivity of 85% in the absence of organic solvents. Combined with characterization results, it was confirmed that the catalyst was layered structure materials, which was supported by a quaternary ammonium salt chain, and the active molecules were distributed between the layered structures. The possible mechanism was also discussed preliminarily.

The performance of blue quantum dot light-emitting diodes (QLEDs) is limited by unbalanced charge injection, resulting from insufficient holes caused by low mobility or significant energy barriers. Here, we introduce an angular-shaped heteroarene based on cyclopentane[b]thiopyran (C8–SS) to modify the hole transport layer poly-N-vinylcarbazole (PVK), in blue QLEDs. C8–SS exhibits high hole mobility and conductivity due to the p···p and S···p interactions. Introducing C8–SS to PVK significantly enhanced hole mobility, increasing it by 2 orders of magnitude from 2.44 × 10–6to 1.73 × 10–4cm2V–1s–1. Benefiting from high mobility and conductivity, PVK:C8–SS-based QLEDs exhibit a low turn-on voltage (Von) of 3.2 V. More importantly, the optimized QLEDs achieve a high peak power efficiency (PE) of 7.13 lm/W, which is 2.65 times that of the control QLEDs. The as-proposed interface engineering provides a novel and effective strategy for achieving high-performance blue QLEDs in low-energy consumption lighting applications.

Let Abe a tame Hecke algebra of type A. We construct two comparison maps between the minimal projective bimodule resolution and the reduced bar resolution of Aby the contracting homotopy, and then we determine the Gerstenhaber algebraic structure and Batalin–Vilkovisky algebraic structure on Hochschild cohomology of A.

The ecological and environmental challenges in rural areas of China are increasingly severe, and farmers' continued participation in environmental governance has emerged as a renewed focal point. However, the participation behaviors in environmental governance represent an ongoing life cycle. Therefore, the study of farmers' sustained engagement in environmental participation is crucial for promoting green and low-carbon development and addressing ecological and environmental problems in China. Drawing on data from the China General Social Survey released in 2017, this paper constructs a theoretical analysis framework of “social network—social fairness perceptions—farmers' continued participation in environmental governance.” Additionally, we employ a structural equation model with bootstrap autonomous sampling method to examine the mediating role of social fairness perceptions. The findings demonstrate that social network, procedural fairness perception, and outcome fairness perception all significantly influence farmers' continued participation in environmental governance. Moreover, social fairness perceptions partially mediate the relationship between social network and farmers' continued participation in environmental governance. Furthermore, higher levels of procedural fairness perception and outcome fairness perception correspond to greater degrees of Chinese farmers' continued participation in environmental governance; conversely, stronger social networks are associated with lower levels of Chinese farmers' continued participation in such activities. This paper aims to elucidate the specific role played by social fairness perceptions within Chinese farmers' continued participation in environmental governance and to actively explore the policy implications.

In the process of micro-milling complex structures, radial throw is likely to cause lower dimensional/form accuracy, which will severely affect the performance of the components. Therefore, it is necessary to investigate the source contributing to the radial throw. According to the kinematic process of the radial throw arising from the attachment errors of the micro milling cutters, a mathematical model considered the attachment errors and the variable section geometry of the micro milling cutters was established to predict the radial throw on the basis of the principle of minimum total potential energy and the Timoshenko beam theory. In comparison to the mathematical model, the proposed finite element model (FEM) presetting the attachment errors shows the effect of modal vibration and the variation of radial throw with attachment errors. To further investigate the environmental factors influencing the radial throw, a measurement method based on the laser measurement system is presented to achieve the on-machine measurement of runout, and a specific extraction method of attachment errors was proposed to help validate the mathematical model. The difference between the results of the mathematical model, FEM, and the experiment is not exceeding 10 % within 3 μm of the maximum runout. Radial throw varies strongly with attachment errors, and the high rotation speed will aggravate the system instability caused by the attachment errors. The main contributor among experimental factors to the variation of runout is the form accuracy of micro milling cutters, accounting for 4.7 % at the highest. This method can provide a theoretical basis for the sources of unbalanced cutting force analysis and the improvement of dimensional/form accuracy.

Recent advances in materials and semiconductor technologies have led to extensive research on optical integration in wearable, implantable, and swallowable health devices. These optical systems utilize the properties of light─intensity, wavelength, polarization, and phase─to monitor and potentially intervene in various biological events. The potential of these devices is greatly enhanced through the use of multifunctional optical materials, adaptable integration processes, advanced optical sensing principles, and optimized artificial intelligence algorithms. This synergy creates many possibilities for clinical applications. This Perspective discusses key opportunities, challenges, and future directions, particularly with respect to sensing modalities, multifunctionality, and the integration of miniaturized optoelectronic devices. We present fundamental insights and illustrative examples of such devices in wearable, implantable, and swallowable forms. The constant pursuit of innovation and the dedicated approach to critical challenges are poised to influence diverse fields.

• A novel heterogenous lamellar Ti 2 AlC/TiAl composite was fabricated. • The as-prepared composite possesses superior strength-plasticity synergy. • Synergetic effects of Ti 2 AlC, lamellar architecture and interface are realized. Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the development of next-generation aerospace engines. By adopting the nacre-like architecture design strategy, we have obtained a novel heterogeneous lamellar Ti 2 AlC/TiAl composite with superior strength-plasticity synergy, i.e., compressive strength of ∼2065 MPa and fracture strain of ∼27%. A combination of micropillar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti 2 AlC reinforcement, lamellar architecture and heterogeneous interface. More specifically, multiple deformation modes in Ti 2 AlC, i.e., basal-plane dislocations, atomic-scale ripples and kink bands, could be activated during the compression, thus promoting the plastic deformation capability of composite. Meanwhile, the lamellar architecture could not only induce significant stress redistribution and crack deflection between Ti 2 AlC and TiAl, but also generate high-density SFs and DTs interactions in TiAl, leading to an improved strength and strain hardening ability. In addition, profuse unique Ti 2 AlC(1 1 ¯ 0 3 ¯)/TiAl(111) interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mechanisms. These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature. [ABSTRACT FROM AUTHOR]

With the development of communication technology, the allocation of frequency spectrum is becoming more intensive. As an important communication component, reconfigurable filters are widely used in various parts of the communication system. We demonstrate a dual-band reconfigurable (switchable) microstrip bandpass filter working in two sub-6-GHz frequency bands based on controllable grounding topology (CGT), which can achieve an ultrafast tuning speed up to ~2 ns, a low bias voltage of ~3.0 V, and a high linearity up to +42.5 dBm in third-order intercept point (IP3). We also use the multilayer design to reduce the interference of the bias circuit, and finally, a portable 5G signal detector is proposed, showing the promising application prospects of the proposed switchable bandpass filter.

In the present work, Ti2AlC/TiAl composites with network architecture were fabricated by the method of spark plasma sintering (SPS) at different temperature using Ti–48Al–2Cr–2Nb pre-alloyed powders and graphene nanosheets (GNSs) as raw materials. The effect of sintering temperature on the multi-scale microstructure evolution and mechanical properties of Ti2AlC/TiAl composites with network architecture was investigated. The results showed that equiaxed γ-TiAl matrix composite reinforced with the continuous network structured micro-Ti2AlC phases could be in-situ fabricated at the sintering temperature of 1200 °C. With the increase of sintering temperature from 1200 °C to 1320 °C, the micro-Ti2AlC continuous network structure gradually transforms into the nearly continuous, quasi-continuous and semi-continuous network. While the equiaxed γ-TiAl matrix gradually transforms into duplex, nearly lamellar, fully lamellar TiAl. Meanwhile, the micro-nano Ti2AlC precipitates would be formed in the TiAl matrix when the sintering temperature exceeds 1200 °C. When the sintering temperature is 1310 °C, the near lamellar TiAl matrix composite reinforced with the quasi-continuous network structured micro-Ti2AlC phases and micro-nano Ti2AlC precipitates is obtained, and the as-prepared composite possesses the best mechanical properties at both room and high temperature due to the synthetic effect of quasi-continuous network structure, intrinsic properties of Ti2AlC and lamellar TiAl.

Luminescence intensity in photodetectors, radiation imagers and light-emitting diodes is proportional to the thickness of the light-emitting layer. However, a thick emitting layer reduces light output because of incoherent photon scattering and attenuation. Here we present the design of double-tapered optical-fibre arrays that can drastically increase the light output of thick light-emitting layers by progressively filling more propagation modes along the fibre’s depth. To enhance the light-collection efficiency and imaging resolution, the upper taper angle of each fibre is greater than the lower angle. By filling the fibre substrate with perovskite nanocrystals from a scale of micrometres thick to centimetres thick, large-scale pixel-dense X-ray or gamma-ray detector arrays can be fabricated. We demonstrate X-ray imaging with a spatial resolution of 22 lp mm−1. Pixelated gamma-ray imaging is also demonstrated using a nanocrystal scintillator film with a thickness of 4 mm and ~10,000 pixels under focused 6-MeV irradiation. Dynamic changes in the energy spectrum (5 keV to 10 MeV) and dose rate (3.5 nGy s−1to 96 mGy s−1) can be conveniently monitored using a hemispherical fibre array dosimeter with a field of view of 150°. This study presents a high-throughput approach for fabricating thick emitter layers that could be applied to biomolecular or mechanical force sensing, medical imaging and ion beam therapy.

Colloidal nanocrystals (NCs) have shown remarkable promise for optoelectronics, energy harvesting, photonics, and biomedical imaging. In addition to optimizing quantum confinement, the current challenge is to obtain a better understanding of the critical processing steps and their influence on the evolution of structural motifs. Computational simulations and electron microscopy presented in this work show that nanofaceting can occur during nanocrystal synthesis from a Pb-poor environment in a polar solvent. This could explain the curved interfaces and the olivelike-shaped NCs observed experimentally when these conditions are employed. Furthermore, the wettability of the PbS NCs solid film can be further modified via stoichiometry control, which impacts the interface band bending and, therefore, processes such as multiple junction deposition and interparticle epitaxial growth. Our results suggest that nanofaceting in NCs can become an inherent advantage when used to modulate band structures beyond what is traditionally possible in bulk crystals.

Light-field detection measures both the intensity of light rays and their precise direction in free space. However, current light-field detection techniques either require complex microlens arrays or are limited to the ultraviolet–visible light wavelength ranges1–4. Here we present a robust, scalable method based on lithographically patterned perovskite nanocrystal arrays that can be used to determine radiation vectors from X-rays to visible light (0.002–550 nm). With these multicolour nanocrystal arrays, light rays from specific directions can be converted into pixelated colour outputs with an angular resolution of 0.0018°. We find that three-dimensional light-field detection and spatial positioning of light sources are possible by modifying nanocrystal arrays with specific orientations. We also demonstrate three-dimensional object imaging and visible light and X-ray phase-contrast imaging by combining pixelated nanocrystal arrays with a colour charge-coupled device. The ability to detect light direction beyond optical wavelengths through colour-contrast encoding could enable new applications, for example, in three-dimensional phase-contrast imaging, robotics, virtual reality, tomographic biological imaging and satellite autonomous navigation.

Calibration for asymmetry of the simultaneously electromagnetic near-field probing system is a good way of improving the performance of a two-port probe. The previous rotating asymmetric calibration method (RACM) based on microstrip line measurements at two directions of 0° and 90° is limited to 12 GHz. In this article, a nonrotating asymmetric calibration method (NRACM) is proposed for ultrawideband calibration of a simultaneously near-field probing system. A four-port vector network analyzer and a highly symmetric grounded coplanar waveguide (GCPW) calibrator are used to solve the calibration matrix in the proposed method. It only needs to place the probe at one direction of 0° instead of measurements at two directions and uses the time-domain reflectometry (TDR) for localization of the probe loop. These simplified measurement steps in the proposed method reduce the impact of positioning error. The non-TEM effect is automatically avoided because of no 90° measurement. A highly symmetric ultrawideband GCPW calibrator without soldering is adopted to excite standard electromagnetic fields for calibration. The measurement results of standing waves demonstrate that the proposed method is suitable for asymmetric calibration at a frequency as high as 20 GHz.

InP quantum dots (QDs) are attracting significant interest as a potentially less toxic alternative to Cd-based QDs in many research areas. Although InP-based core/shell QDs with excellent photoluminescence properties have been reported so far, sophisticated interface treatment to eliminate defects is often necessary. Herein, using aminophosphine as a seeding source of phosphorus, we find that H2S can be efficiently generated from the reaction between a thiol and an alkylamine at high temperatures. Apart from general comprehension that H2S acts as a S precursor, it is revealed that with core etching by H2S, the interface between InP and ZnS can be reconstructed with S2−incorporation. Such a transition layer can reduce inherent defects at the interface, resulting in significant photoluminescence (PL) enhancement. Meanwhile, the size of the InP core could be further controlled by H2S etching, which offers a feasible process to obtain wide band gap InP-based QDs with blue emission.

Learning with feature evolution studies the scenario where the features of the data streams can evolve, i.e., old features vanish and new features emerge. Its goal is to keep the model always performing well even when the features happen to evolve. To tackle this problem, canonical methods assume that the old features will vanish simultaneously and the new features themselves will emerge simultaneously as well. They also assume that there is an overlapping period where old and new features both exist when the feature space starts to change. However, in reality, the feature evolution could be unpredictable, which means that the features can vanish or emerge arbitrarily, causing the overlapping period incomplete. In this article, we propose a novel paradigm: prediction with unpredictable feature evolution (PUFE) where the feature evolution is unpredictable. To address this problem, we fill the incomplete overlapping period and formulate it as a new matrix completion problem. We give a theoretical bound on the least number of observed entries to make the overlapping period intact. With this intact overlapping period, we leverage an ensemble method to take the advantage of both the old and new feature spaces without manually deciding which base models should be incorporated. Theoretical and experimental results validate that our method can always follow the best base models and, thus, realize the goal of learning with feature evolution.

Transdermal delivery is an attractive route for the treatment of skin disease. However, its therapeutic effectiveness is significantly hampered by the stratum corneum and cell membrane barriers. Herein, we reported a novel liposomes incorporated microneedles (MNs) delivery platform to address these two key challenges. Conventional liposomes were surface modified with membrane-anchoring fusogenic proteins mimicking pH-responsive, comb-like pseudopeptides containing relatively long alkyl side chains. The liposomes-containing MNs were fabricated with biodegradable and biocompatible silk fibroin with sufficient mechanical strength using micromolding technology. The degradation and release profile of liposomes from the MNs delivery platform can be manipulated by controlling the liposomes to silk fibroin ratio, and the released liposomes well-maintained their original spherical shape and pH-responsive functionality. Remarkably enhanced in vitro skin permeation was observed in the polymer modified liposomes incorporating MNs delivery platform compared to the ones without MNs facilitation. Enhanced cellular uptake and potency against cancer cells of the pH-responsive, comb-like pseudopeptides modified liposomes incorporating MNs delivery platform were demonstrated. These results suggest its potential applications for efficient skin penetration and enhanced cellular uptake, which is of crucial importance for skin disease treatment.

Doping Ce in La2O 2CO 3 could promote transformation and migration of oxygen species at low temperature, and decrease the OCM reaction temperature of lanthanum-based catalyst.

The recent advancements in higher-order topology have provided unprecedented opportunities in optical device designs and applications. Here, we propose a new, to the best of our knowledge, method to realize rainbow trapping based on higher-order topological corner modes (HOTCMs), which are constructed by two configurations of breathing kagome photonic crystals with distinct topological phases. Interestingly, the HOTCMs localized at corners with different geometric configurations are found to be frequency dispersive and thus initiate the possible application in realizing rainbow trapping. By designing a polygon structure containing several configurations of corners, we demonstrate that the HOTCMs can be excited with the frequency sequence locked to the corner order (clockwise/anticlockwise direction) in the polygon. The reported HOTCMs provide a new mechanism to realize multiple-frequency trapping, which may find potential applications in future integrated photonics.

In this paper, we consider the generalized prize-collecting Steiner forest problem with submodular penalties (GPCSF-SP problem). In this problem, we are given an undirected connected graph G=(V,E)and a collection of disjoint vertex subsets V={V1,V2,⋯,Vl}. Assume c:E→R+is an edge cost function and π:2V→R+is a submodular penalty function. The objective of the GPCSF-SP problem is to find an edge subset Fsuch that the total cost including the edge cost in Fand the penalty cost of the subcollection Scontaining these Vinot connected by Fis minimized. By using the primal-dual technique, we give a 3-approximation algorithm for this problem.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to more than 5 million deaths worldwide to date. Due to the limited therapeutic options so far available, target-based virtual screening with LC/MS support was applied to identify the novel and high-content compounds 1–4with inhibitory effects on SARS-CoV-2 in Vero E6 cells from the plant Dryopteris wallichiana. These compounds were also evaluated against SARS-CoV-2 in Calu-3 cells and showed unambiguous inhibitory activity. The inhibition assay of targets showed that compounds 3and 4mainly inhibited SARS-CoV-2 3CLpro, with effective Kdvalues. Through docking and molecular dynamics modeling, the binding site is described, providing a comprehensive understanding of 3CLpro and interactions for 3, including hydrogen bonds, hydrophobic bonds, and the spatial occupation of the B ring. Compounds 3and 4represent new, potential lead compounds for the development of anti-SARS-CoV-2 drugs. This study has led to the development of a target-based virtual screening method for exploring the potency of natural products and for identifying natural bioactive compounds for possible COVID-19 treatment.

Graphical abstract:

After injury, the endometrium cannot self-repair or regenerate because damage to the uterine basal layer often leads to intrauterine adhesions (IUAs), which can cause serious problems such as infertility and recurrent miscarriage. At present, no clinically effective method is available for the treatment of IUAs. With its advantages of being individualized and precise, three-dimensional (3D) bioprinting technology has been used to regenerate various damaged tissues and organs. Granulate colony-stimulating factor (G-CSF) clearly plays a positive role in endometrial regeneration, but precise and individualized drug applications are a prerequisite for improving the therapeutic effect of G-CSF. This study utilized a 3D-printed hydrogel in combination with a sustained-release microsphere (SRM) system to prepare a 3D-printed G-CSF-SRM system (3D microsphere) in vitro. The system advantageously allowed the spatial control of drug distribution and structural individualization. In addition to being long-acting and having a sustained release, the 3D microspheres increased the local concentration of G-CSF. Using a Sprague–Dawley rat IUA model, we confirmed that the 3D microspheres promoted local endometrial regeneration, significantly suppressed endometrium tissue fibrosis, and improved endometrial cell (epithelial and stromal cell) and vascular regeneration. The 3D microspheres significantly improved the endometrial receptivity and restored the pregnancy function of the damaged endometrium. We believe that the 3D-printed G-CSF-SRM hydrogel scaffold design concept may be used to develop a more precise and individualized treatment method for the structural and functional repair of damaged endometrial tissues.