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Topological Dirac nodal-line semimetals host topologically nontrivial electronic structure with nodal-line crossings around the Fermi level, which could affect the photocarrier dynamics and lead to novel relaxation mechanisms. Herein, by using time- and angle-resolved photoemission spectroscopy, we reveal the previously inaccessible linear dispersions of the bulk conduction bands above the Fermi level in a Dirac nodal-line semimetal PtSn4, as well as the momentum and temporal evolution of the gapless nodal lines. A surprisingly ultrafast relaxation dynamics within a few hundred femtoseconds is revealed for photoexcited carriers in the nodal line. Theoretical calculations suggest that such ultrafast carrier relaxation is attributed to the multichannel scatterings among the complex metallic bands of PtSn4via electron–phonon coupling. In addition, a unique dynamic relaxation mechanism contributed by the highly anisotropic Dirac nodal-line electronic structure is also identified. Our work provides a comprehensive understanding of the ultrafast carrier dynamics in a Dirac nodal-line semimetal.

The discovery of room-temperature ferromagnetism in van der Waals (vdW) materials opens new avenues for exploring low-dimensional magnetism and its applications in spintronics. Recently, the observation of the room-temperature topological Hall effect in the vdW ferromagnet Fe3GaTe2suggests the possible existence of room-temperature skyrmions, yet skyrmions have not been directly observed. In this study, real-space imaging was employed to investigate the domain evolution of the labyrinth and skyrmion structure. First, Ne´el-type skyrmions can be created at room temperature. In addition, the influence of flake thickness and external magnetic field (during field cooling) on both labyrinth domains and the skyrmion lattice is unveiled. Due to the competition between magnetic anisotropy and dipole interactions, the specimen thickness significantly influences the density of skyrmions. These findings demonstrate that Fe3GaTe2can host room-temperature skyrmions of various sizes, opening up avenues for further study of magnetic topological textures at room temperature.

This research aims to study the diverse surface topographical features that emerge on both longitudinal and latitudinal facets' external and internal surfaces of a bespoke ball artefact. The focus variation measurement technique is employed to visually inspect the surface quality derived from a plethora of surface topographical defects and asperities namely balling, staircase effect, spatters, and un-melted/partially melted particles. These diverse defects, asperities and associated surface quality are characterised and correlated with an array of suitable areal surface texture height and hybrid parameters, and quantified with newly developed feature-based particle analysis mentioned in ISO 25178-2. The longitudinal facet external surfaces measurement range is selected from 15° to 135°, while internal surfaces measurement is performed between 15° to 165°. Similarly, the latitudinal facet external and internal surfaces are examined by full-turn at the equator. A comprehensive statistical analysis of variance (ANOVA) is employed to examine the statistical significance of inclinations angles, build orientations, and types of surfaces. The experimental results and ANOVA analysis showed that a strong interrelationship exists between the different build inclination angles and the distinct surface topographical features that emerge on longitudinal facet external and internal surfaces, while the latitudinal facet external and internal surfaces presented minimal difference in surface quality.

Tuning the interfacial Schottky barrier with van der Waals (vdW) contacts is an important solution for two-dimensional (2D) electronics. Here we report that the interlayer dipoles of 2D vdW superlattices (vdWSLs) can be used to engineer vdW contacts to 2D semiconductors. A bipolar WSe2with Ba6Ta11S28(BTS) vdW contact was employed to exhibit this strategy. Strong interlayer dipoles can be formed due to charge transfer between the Ba3TaS5and TaS2layers. Mechanical exfoliation breaks the superlattice and produces two distinguished surfaces with TaS2and Ba3TaS5terminations. The surfaces thus have opposite surface dipoles and consequently different work functions. Therefore, all the devices fall into two categories in accordance with the rectifying direction, which were verified by electrical measurements and scanning photocurrent microscopy. The growing vdWSL family along with the addition surface dipoles enables prospective vdW contact designs and have practical application in nanoelectronics and nano optoelectronics.

ABSTRACTTwo new species of the click-beetle genus SelatosomusStephens, S. heliisp. nov. and S. zenghuaesp. nov., are described from Sichuan Province, China. Habitus and diagnostic characters of the new species are illustrated. A key to the Selatosomusspecies from Sichuan Province is provided.

Superconductivity in low-dimensional compounds has attracted considerable interest. In this study, we report a new layered Pd-based type-II superconductor, Ca2Pd3Sb4, which contains CaPd2Sb3of CaBe2Ge2blocks and CaPdSb of CeMg2Si2blocks that are stacked alternately along the crystallographic caxis. The measured electrical resistivity, magnetic susceptibility, and specific heat of the Ca2Pd3Sb4crystals, which are grown via a self-flux method, consistently demonstrate bulk superconductivity at about 1.30 K. Further analyses of the data indicate strong anisotropic behavior with the parameter γ ∼ 3.8 along the abplane and caxis. Longitudinal magnetotransport measurements up to ∼18 T reveal notable Shubnikov–de Haas oscillations with a single frequency (F= 462 T), demonstrating the existence of an electron pocket in the Brillouin zone. First-principles calculation reveals that the metallicity of the compound with a quasi-two-dimensional Fermi surface and the dorbitals of Pd and porbitals of Sb are the main contributors to the total density of states at the Fermi level in Ca2Pd3Sb4.

Terrestrial dissolved organic matter (DOM) is critical to global carbon and nutrient cycling, climate change, and human health. However, how the spatial and compositional differences of soil DOM affect its dynamics and fate in water during the carbon cycle is largely unclear. Herein, the biodegradation of DOM from 14 spatially distributed grassland soils in China with diverse organic composition was investigated by 165 days of incubation experiments. The results showed that although the high humified fraction (high-HS) regions were featured by high humic-like fractions of 4–25 kDa molecular weight, especially the abundant condensed aromatics and tannins, they unexpectedly displayed greater DOM degradation during 45–165 days. In contrast, the unique proteinaceous and 25–100 kDa fractions enriched in the low humified fraction (low-HS) regions were drastically depleted and improved the decay of bulk DOM but only during 0–45 days. Together, DOM from the high-HS regions would cause lower CO2outgassing to the atmosphere but higher organic loads for drinking water production in the short term than that from the low-HS regions. However, this would be reversed for the two regions during the long-term transformation processes. These findings highlight the importance of spatial and temporal variability of DOM biogeochemistry to mitigate the negative impacts of grassland soil DOM on climate, waters, and humans.

The {K2,Cn}-factor of a graph is a spanning subgraph whose each component is either K2or Cn. In this paper, a sufficient condition with regard to tight toughness, isolated toughness and binding number bounds to guarantee the existence of the {K2,C2i+1|i⩾2}-factor for any graph is obtained, which answers a problem due to Gao and Wang (J Oper Res Soc China, 2021. https://doi.org/10.1007/s40305-021-00357-6).

The impact-abrasive wear behavior of high-C martensitic steel was investigated, taking into account varying carbon (C) contents and different tempering temperatures. The evaluation was done through comprehensive microstructural characterization, analysis of worn surface morphology, and measurement of key performance like impact toughness and surface hardening. The findings demonstrate that increasing C content and tempering temperature both has a positive effect on wear resistance, with C content exhibiting a more pronounced influence compared to the tempering temperature. The improved wear resistance of the steel with higher C content and tempering at a higher temperature can be attributed to its enhanced impact toughness. This increase in impact toughness is primarily a result of microstructural refinement and alterations in carbide morphology. Moreover, cyclic impact loading induces surface hardening due to dislocation strengthening within the martensite and the retained austenite, leading to an increase in surface hardness. The combination of surface hardening and excellent impact toughness synergistically contributes to the overall improved wear resistance observed in the experimental steel with higher C content after tempering at a higher temperature. Additionally, the dominant features observed on the worn surface are scratches and substrate delamination, indicative of a wear mechanism of the experimental steels characterized by micro-cutting/ploughing and fatigue wear.

The development of high-temperature nondestructive testing (NDT) requires ultrasonic transducers with good temperature resistance and high sensitivity for improved detection efficiency. Piezoelectric composite can improve the performance of transducers because of its high electromechanical coupling coefficient and adjustable acoustic impedance. In this study, 1-3-2 composites and 1-3-2 high-temperature composite ultrasonic transducers (HTCUTs) based on 0.36BiScO3-0.64PbTiO3 (BSPT), which is preferred piezoelectric materials at $200~^{\circ }$ C– $300~^{\circ }$ C, and high-temperature epoxy with a center frequency of 6 MHz were designed and fabricated. From $25~^{\circ }$ C to $250~^{\circ }$ C, 1-3-2 composites show a higher electromechanical coupling coefficient ${k}_{t}$ especially at high temperatures (~0.53 at $25~^{\circ }$ C and ~0.64 at $250~^{\circ }$ C) than monolithic BSPT (~0.5). The signal of the pulse-echo response of 1-3-2 HTCUTs is distinguishable up to $250~^{\circ }$ C and remains stable ( ${V}_{\text {pp}}~\sim 500$ mV) below $150~^{\circ }$ C, exhibiting higher sensitivity (improved by 7 dB) than that of monolithic BSPT high-temperature ultrasonic transducers (HTUTs). Bandwidth has been greatly enhanced especially at high temperatures (~103% at $250~^{\circ }$ C) compared with that of monolithic BSPT HTUTs (~30% at $250~^{\circ }$ C). To verify the excellent performance, B-mode scanning imaging measurement of a stepped steel block and defect location detection of a steel block was performed, showing the potential for high-temperature NDT applications.

In this article, we first reveal the performance degradation and physical failure mechanism of a lab-designed GaN power amplifier (PA) module based on a commercial GaN high-electron-mobility transistor (HEMT) with high-power electromagnetic pulse injected. We carried out a systematic step pulse injection experiment to hunt out the degradation and failure threshold of PA module by monitoring its S-parameter and the gate-source resister (RGS) of GaN HEMT. Moreover, the performance indexes of GaN PA, including gain, power-added efficiency, output power, and signal-to-noise ratio, have been measured before/after degradation for comparative analysis. The intact surface circuit microscope of PA module and the degradation electrical characteristics of GaN HEMT demonstrated that the GaN HEMT is the vulnerable component of GaN PA. Furthermore, the numerical simulations and decapsulation experiments are carried out for GaN HEMT to gain insight into the failure process and physical failure mechanism. The results reveal that the failure mode is thermal-induced gate metal melting of the GaN HEMT. The failure mechanism is mainly attributable to the impact ionization, which induced by the high pulse voltage under the gate near the source. This is followed by the thermal–electrical feedback state in the device internal until the temperature finally reaching the melting point of the gate metal.

Zero-shot image recognition aims to classify data from unseen classes, by exploring the association between visual features and the semantic representations of each class. Most existing approaches focus on learning a shared single-scale embedding space (often at the output layer of the network) for both visual and semantic features, ignoring a fact that different-scale visual features exhibit different semantics. In this article, we propose a multi-scale visual-attribute co-attention (mVACA) model, considering both visual-semantic alignment and visual discrimination at multiple scales. At each scale, a hybrid visual attention is realized by attribute-related attention and visual self-attention. The attribute-related attention is guided by a pseudo attribute vector inferred via a mutual information regularization (MIR). The visual self-attentive features further influence the attribute attention to emphasize visual-associated attributes. Leveraging multiscale visual discrimination, mVACA unifies standard zero-shot learning (ZSL) and generalized ZSL tasks in one framework, achieving state-of-the-art or competitive performance on several commonly used benchmarks of both setups. To better understand the interaction between images and attributes in mVACA, we also provide visualized analysis.

The microstructure evolution and properties of medium-carbon cast steel alloyed with different Ni contents after tempering at various temperatures have been investigated. The addition of 0.47–1.59 wt.% Ni content results in the formation of 16%–36% retained austenite (RA). The blocky and irregular-polygonal RA mainly forms along the prior austenite grain boundaries, and the tempering temperature does not affect the RA content. The hardness of medium-carbon cast steel is affected by the precipitation of carbides and the hardness of martensite. Excessive RA content is the main cause of intergranular impact rupture and low impact energy. The long-strip carbides formed after tempering at 320 °C would further reduce the impact energy of medium-carbon cast steel. When tempering at 220 and 380 °C, the increase in impact energy is attributed to the formation of rod-like and spherical carbides and the low-carbon martensite. For the medium-carbon cast steel with high impact energy, its impact-abrasive wear resistance is more excellent. Micro-cutting and delamination are the primary wear mechanisms.

Promoting the catalyst performance for oxygen reduction reaction (ORR) in energy conversion devices through controlled manipulation of the structure of catalytic active sites has been a major challenge. In this work, we prepared Fe–N–C single-atom catalysts (SACs) with Fe–N5active sites and found that the catalytic activity of the catalyst with shrinkable Fe–N5–C11sites for ORR was significantly improved compared with the catalyst bearing normal Fe–N5–C12sites. The catalyst C@PVI-(TPC)Fe-800, prepared by pyrolyzing an axial-imidazole-coordinated iron corrole precursor, exhibited positive shifted half-wave potential (E1/2= 0.89 V vs RHE) and higher peak power density (Pmax= 129 mW/cm2) than the iron porphyrin-derived counterpart C@PVI-(TPP)Fe-800 (E1/2= 0.81 V, Pmax= 110 mW/cm2) in 0.1 M KOH electrolyte and Zn–air batteries, respectively. X-ray absorption spectroscopy (XAS) analysis of C@PVI-(TPC)Fe-800 revealed a contracted Fe–N5–C11structure with iron in a higher oxidation state than the porphyrin-derived Fe–N5–C12counterpart. Density functional theory (DFT) calculations demonstrated that C@PVI-(TPC)Fe-800 possesses a higher HOMO energy level than C@PVI-(TPP)Fe-800, which can increase its electron-donating ability and thus help achieve enhanced O2adsorption as well as O–O bond activation. This work provides a new approach to tune the active site structure of SACs with unique contracted Fe–N5–C11sites that remarkably promote the catalyst performance, suggesting significant implications for catalyst design in energy conversion devices.

Micro-Doppler analysis (MDA) of the rigid-body target is significant for attitude estimation and recognition of space objects. The traditional MDA method for rigid-body targets includes two sequential steps. First, the time–frequency analysis is performed on the radar echo data of the target, and then, the micro-Doppler curve of each scattering center is separated and extracted from the time–frequency map. The second step depends on the micro motion model of the target. In the MDA of the real rigid-body target, there are some problems, such as the mismatch of the micro motion model, the incidence angle dependence of the scattering center position, and the partial occlusion of the scattering center. Therefore, it is very difficult to correctly extract the micro-Doppler curves of multiple scatterers. In this article, an end-to-end MDA method for rigid-body targets based on a deep learning network is proposed, which can directly separate and extract the micro-Doppler curves of multiple scatterers from the target echo data. Specifically, an asymmetrical autoencoding (A2E) network equipped with a data preprocessing (DP2) module is developed to extract time–frequency curves (TFCs) from radar echoes. Considering the sparseness of time–frequency distribution (TFDs), we then develop a novel energy-concentration objective (ECO) function based on min–max game to enhance curves energy while suppressing the background energy. In practice, measured TFDs are rarely annotated; they restrict the generalization capability of the A2E from the simulation to the measurement. To bridge the gap, twofold modifications are finally constructed: 1) we insert a partial-shared branch of the decoder to reconstruct the TFD from the DP2 module and 2) we regularize the ECO function with a knowledge preservation-based reconstruction bound to further capture the characteristics of measured echoes in a semisupervised way at test time to relieve the domain-shift problem.

Endoscopes are ubiquitous in minimally invasive or keyhole surgeries globally. However, frequent removal of endoscopes from the patient’s body due to the lens contaminations results in undesirable consequences. Therefore, a cost-effective process chain to fabricate thermoplastic-based endoscope lenses with superior antifouling and optical properties is proposed in this research. Such multifunctional surface response was achieved by lubricant impregnation of nanostructures. Two types of topographies were produced by femtosecond laser processing of metallic molds, especially to produce single-tier laser-induced periodic surface structures (LIPSS) and two-tier multiscale structures (MS). Then, these two LIPSS and MS masters were used to replicate them onto two thermoplastic substrates, namely polycarbonate and cyclic olefin copolymer, by using hot embossing. Finally, the LIPSS and MS surfaces of the replicas were infiltrated by silicone oils to prepare lubricant-impregnated surfaces (LIS). Droplet sliding tests revealed that the durability of the as-prepared LIS improved with the increase of the lubricant viscosity. Moreover, the single-tier LIPSS replicas exhibited longer-lasting lubricant conservation properties than the MS ones. Also, LIPSS-LIS replicas demonstrated an excellent optical transparency, better than the MS-LIS ones, and almost match the performance of the reference polished ones. Furthermore, the LIPSS-LIS treatment led to superior antifouling characteristics, i.e., regarding fogging, blood adhesion, protein adsorption, and microalgae attachment, and thus demonstrated its high suitability for treating endoscopic lenses. Finally, a proof-of-concept LIPSS-LIS treatment of endoscope lenses was conducted that confirmed their superior multifunctional response.

Recent optical stimulation suggests a vital non-contact pathway to manipulate both macroscopic and microscopic ferroelectric properties and paves the foundation for optoelectronics devices. However, up to date, most optical-related manipulation of ferroelectric properties is restricted due to their intrinsic bandgap and limited visible light spectrum absorption. Here, we reveal non-oxide Sn2P2S6single crystal possesses full-visible-spectrum absorption (from 300 to 800 nm) with a unique disproportionation mechanism of photoexcited Sn ions and Urbach tail, which is not contradicting to the intrinsic band gap. Interestingly, we observed the existence of conductive domain walls (c-DW) and the light illumination induced significant enhancement of the domain wall conductivity caused by such disproportionation reaction. In addition, the domains separated by c-DW also exhibited noticeable electrical conductivity difference in the presence of optical illumination owing to the interfacial polarization charge with opposite signs. The result provides a novel opportunity for understanding the electrical conductivity behavior of the domains and domain walls in ferroelectrics with full-visible-spectrum absorption and achieving greatly enhanced performances for optoelectronics.

The adsorption of tetracycline wastewater has garnered significant attention owing to its potential threats to human health and the ecological environment during excessive flooding. In this study, a novel Fe-based biomass aerogel (FGA) was synthesized using a microwave-assisted method for efficient tetracycline (TC) adsorption. FGA exhibited exceptional stability, wide adaptability, and excellent recyclability while demonstrated extremely high adsorption (up to 1366 mg·g−1) for TC at room temperature. The synthesized FGA was experimentally characterized through morphological observation and determination of chemical composition. The effects of different pH levels, initial concentration of TC, adsorption dosage, and coexisting inorganic ions on the adsorption performance of TC adsorption in experimental studies. The adsorption process of TC onto the FGA was heat-absorbing and spontaneous, aligning with the proposed pseudo-second-order kinetic model and Freundlich isothermal model. Electrostatic interaction, hydrogen bonding interaction, complexation and pore filling were identified as involved mechanisms during the adsorption process based on both characterization results and adsorption experiments.

Earth’s radiation budget and frequency and intensity of precipitation are influenced by aerosols with ice nucleation activity (INA), i.e., particles that catalyze the formation of ice. Some bacteria, fungi, and pollen are among the most efficient ice nucleators but the molecular basis of INA is poorly understood in most of them. Lysinibacillus parviboronicapiens(Lp) was previously identified as the first Gram-positive bacterium with INA. INA of Lpis associated with a secreted, nanometer-sized, non-proteinaceous macromolecule or particle. Here a combination of comparative genomics, transcriptomics, and a mutant screen showed that INA in Lpdepends on a type I iterative polyketide synthase and a non-ribosomal peptide synthetase (PKS-NRPS). Differential filtration in combination with gradient ultracentrifugation revealed that the product of the PKS-NRPS is associated with secreted particles of a density typical of extracellular vesicles and electron microscopy showed that these particles consist in “pearl chain”-like structures not resembling any other known bacterial structures. These findings expand our knowledge of biological INA, may be a model for INA in other organisms for which the molecular basis of INA is unknown, and present another step towards unraveling the role of microbes in atmospheric processes.

Laser Powder Bed Fusion process is regarded as the most versatile metal additive manufacturing process, which has been proven to manufacture near net shape up to 99.9% relative density, with geometrically complex and high-performance metallic parts at reduced time. Steels and iron-based alloys are the most predominant engineering materials used for structural and sub-structural applications. Availability of steels in more than 3500 grades with their wide range of properties including high strength, corrosion resistance, good ductility, low cost, recyclability etc., have put them in forefront of other metallic materials. However, LPBF process of steels and iron-based alloys have not been completely established in industrial applications due to: (i) limited insight available in regards to the processing conditions, (ii) lack of specific materials standards, and (iii) inadequate knowledge to correlate the process parameters and other technical obstacles such as dimensional accuracy from a design model to actual component, part variability, limited feedstock materials, manual post-processing and etc. Continued efforts have been made to address these issues. This review aims to provide an overview of steels and iron-based alloys used in LPBF process by summarizing their key process parameters, describing thermophysical phenomena that is strongly linked to the phase transformation and microstructure evolution during solidification, highlighting metallurgical defects and their potential control methods, along with the impact of various post-process treatments; all of this have a direct impact on the mechanical performance. Finally, a summary of LPBF processed steels and iron-based alloys with functional properties and their application perspectives are presented. This review can provide a foundation of knowledge on LPBF process of steels by identifying missing information from the existing literature.

Revealing the ultrafast dynamics of three-dimensional (3D) Dirac fermions is critical for both fundamental science and device applications. So far, how the cooling of 3D Dirac fermions differs from that of two-dimensional (2D) and whether there is population inversion are fundamental questions to be answered. Here we reveal the ultrafast dynamics of Dirac fermions in a model 3D Dirac semimetal Cd3As2by time- and angle-resolved photoemission spectroscopy with a tunable probe photon energy. The energy- and momentum-resolved relaxation rate shows a linear dependence on the energy, suggesting Dirac fermion cooling through intraband relaxation. Moreover, a population inversion is reported based on the observation of accumulated photoexcited carriers in the conduction band with a lifetime of 3.0 ps. Our work provides direct experimental evidence for a long-lived population inversion in a 3D Dirac semimetal, which is in contrast to 2D graphene with a much shorter lifetime.

A squeezed state with higher-order sidebands is a valuable quantum resource for channel multiplexing quantum communication. However, balanced homodyne detection used in nonclassical light detection has a trade-off performance between the detection bandwidth and clearance, in which the verification of a highly squeezing factor faces a challenge. Here, we construct two optical parametric amplifiers with cavity enhancement; one is for the generation of a −10.5 dB squeezed vacuum state, and the other is for all-optical phase-sensitive parametric homodyne detection. Finally, −6.5 dB squeezing at the carrier with 17 pairs of squeezing sidebands (bandwidth of 156 GHz) is directly and simultaneously observed. In particular, for the cavity-enhanced parametric oscillation and detection processes, we analyze the limiting factors of the detectable bandwidth and measurement deviation from the generated value, which indicates that the length difference and propagation loss between two optical parametric amplifiers should be as small as possible to improve the detection performance. The experimental results confirm our theoretical analysis.

Rabbit hepatitis E virus (HEV) has been reported for years and is thought to have the potential for zoonotic transmission from rabbits to humans. As reported, HEV genotype 3 (gt3) is the most prevalent form of HEV in rabbits. To determine the prevalence of HEV in commercial rabbit livers, 176 liver samples were collected from an abattoir in Hebei Province, China. Three (1.7%) samples tested positive for RNA of HEV-ORF2 (open reading frames-2). Sequence analysis showed that the three isolates shared high identities with each other (94.08–98.85%). Further analysis showed that all the rabbit strains clustered together in the branch of HEV gt3. Further study by immunohistochemistry (IHC) assays showed that 131 (74.4%) liver samples were positive for HEV ORF2 protein. Pathological changes including cell degeneration, inflammatory cell infiltration and bile duct epithelial cell hyperplasia were observed under microscopy. These findings indicated the presence of HEV in commercial livers of rabbits. Additional studies should be conducted to investigate the infectivity of rabbit HEV (rHEV) and the potential risks of zoonotic transmission of rHEV from rabbits to human beings.

In this study, the formation mechanism of light aromatics including benzene, toluene, ethylbenzene, xylene, and naphthalene (BTEXN) and the coke growth during catalytic reforming of thermally derived volatiles of cellulose, glucose, and lignin over HZSM-5 under a H2atmosphere were investigated rigorously. The shape selectivity of HZSM-5 coupled with H2as the promoted agent was found to be highly efficient in trapping volatiles to promote the production of BTEXN. The reactivity of the three biopolymers from biomass structures was compared over HZSM-5 to reveal the hydrocarbon pool and the phenolic pool mechanisms, which are the key mechanistic steps for the BTEXN products and the undesired coke. The results of the present work indicated that there are competing adsorption between the reactions of the aromatics formation and the reactions responsible for the catalytic coke. The formation of both the “soft” and the “hard” coke species strongly depends on biomass structures. The main coke species on spent HZSM-5 are polyaromatics formed via ring growth and the heavy aliphatic species with longer chain (C10–C30) formed via chain growth of the C6–C10oligomers. By analyzing the coke location and the coke nature, we proposed the coke growth mechanism in terms of the aliphatic-based cycle and the aromatic-based cycle.

We report a control scheme of entangled sideband modes without coherent amplitude by employing a frequency-comb-type seed beam. In this scheme, each tooth of the frequency comb serves as a control field for the corresponding downconversion mode. Consequently, all the degrees of freedom can be actively controlled, and the entanglement degrees are higher than 6.7 dB for two pairs of sidebands. We believe that this scheme provides a simple solution for the control of sideband modes, which could be further applied to achieve compact channel multiplexing quantum communications.

Aluminum fluoride (AlF3)-modified HZSM-5 obtained by simple mechanical mixing and calcination was used to enhance the conversion of the lignite pyrolysis volatiles to light aromatics. The results revealed that the appropriate amount of AlF3modification can simultaneously dealuminize and aluminize to enhance the catalytic performance, in which dealumination considerably enlarged the pores while realumination generated more midstrength acid sites to compensate for the loss of acid sites caused by dealumination. HZ-2 (HZSM-5 mixed with 2 wt % AlF3) obtained the maximum light aromatics yield of 31.0 mg/g as a result of its abundant mesopores and suitable midstrength acid sites, especially the yield of benzene increased by 6.3 mg/g in comparison with that of the original HZSM-5. However, mixing with only a small amount of AlF3generated the most serious carbon depositions because of the acidity enhancement by the critical role of alumination. Moreover, excessive AlF3etched more framework Al that dramatically reduced the midstrength acid sites, inhibiting the formation of light aromatics, although the enlargement of pore size facilitated mass transfer. This one-step modification combining the expansion of the pore size and the optimization of acid sites provides a promising strategy for upgrading the lignite pyrolysis volatiles.

Neutralizing monoclonal antibodies (nAbs) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represent promising candidates for clinical intervention against coronavirus disease 2019 (COVID-19). We isolated a large number of nAbs from SARS-CoV-2-infected individuals capable of disrupting proper interaction between the receptor binding domain (RBD) of the viral spike (S) protein and the receptor angiotensin converting enzyme 2 (ACE2). However, the structural basis for their potent neutralizing activity remains unclear. Here, we report cryo-EM structures of the ten most potent nAbs in their native full-length IgG-form or in both IgG-form and Fab-form bound to the trimeric S protein of SARS-CoV-2. The bivalent binding of the full-length IgG is found to associate with more RBDs in the “up” conformation than the monovalent binding of Fab, perhaps contributing to the enhanced neutralizing activity of IgG and triggering more shedding of the S1 subunit from the S protein. Comparison of a large number of nAbs identified common and unique structural features associated with their potent neutralizing activities. This work provides a structural basis for further understanding the mechanism of nAbs, especially through revealing the bivalent binding and its correlation with more potent neutralization and the shedding of S1 subunit.

To scale quantum information processing, quantum state distributors are an indispensable technology in quantum networks. We present a universal scheme of a continuous variable quantum state distributor that performs point-to-multipoint distributions via quantum teleportation with partially disembodied transport. The fidelity of the state at the output nodes can be conveniently manipulated as needed by engineering the correlation noise of the Einstein–Podolsky–Rosen (EPR) beam. For a 1→2 distributor, controllable distributions were demonstrated by manipulating the squeezing factor of EPR entanglement. The fidelities of the two receivers gradually changed from (2/3, 2/3) to (0.95, 0.17) corresponding to the transition from symmetric to asymmetric quantum cloning.

Significant progress has been made previously in the research and development of graphene oxide (GO) membranes for water purification, but their biofouling behavior remains poorly understood. In this study, we investigated the biofilm formation and biofouling of GO membranes with different surface microstructures in the context of filtering natural surface water and for an extended operation period (110 days). The results showed that the relatively hydrophilic and smooth Fe(OH)3/GO membrane shaped a thin and spatially heterogeneous biofilm with high stable flux. However, the ability to simultaneously mitigate biofilm formation and reduce biofouling was not observed in the weakly hydrophilic and wrinkled Fe/GO and H–Fe(OH)3/GO membranes. Microbial analyses revealed that the hydrophilicity and roughness distinguished the bacterial communities and metabolic functions. The organic matter-degrading and predatory bacteria were more adapted to hydrophilic and smooth GO surfaces. These functional taxa were involved in the degradation of extracellular polymeric substances (EPS), and improved biofilm heterogeneity. In contrast, the weakly hydrophilic and wrinkled GO surfaces had reduced biodiversity, while unexpectedly boosting the proliferation of EPS-secreting bacteria, resulting in increased biofilm formation and aggravated biofouling. Moreover, all GO membranes achieved sustainable water purification during the entire operating period.

Earth’s radiation budget and frequency and intensity of precipitation are influenced by aerosols with ice nucleation activity (INA), i.e., particles that catalyze the formation of ice. Some bacteria, fungi, and pollen are among the most efficient ice nucleators but the molecular basis of INA is poorly understood in most of them. Lysinibacillus parviboronicapiens(Lp) was previously identified as the first Gram-positive bacterium with INA. INA of Lpis associated with a secreted, nanometer-sized, non-proteinaceous macromolecule or particle. Here a combination of comparative genomics, transcriptomics, and a mutant screen showed that INA in Lpdepends on a type I iterative polyketide synthase and a non-ribosomal peptide synthetase (PKS-NRPS). Differential filtration in combination with gradient ultracentrifugation revealed that the product of the PKS-NRPS is associated with secreted particles of a density typical of extracellular vesicles and electron microscopy showed that these particles consist in “pearl chain”-like structures not resembling any other known bacterial structures. These findings expand our knowledge of biological INA, may be a model for INA in other organisms for which the molecular basis of INA is unknown, and present another step towards unraveling the role of microbes in atmospheric processes.

In the present work, machining performance of a new solid carbide end mill has been investigated during side milling of Ti-6Al-4V. It is observed that adding cooling grooves on the clearance side of the cutting tool improves the tool performance by decreasing tool wear. Tool temperature measurements by infrared camera showed that these grooves decreased the tool temperature during the machining process. In order to understand the mechanisms behind this improvement, simulations of the coolant flow around the tool with and without these grooves are performed. Modelling and simulation results showed that these cooling grooves lead to an increase in the velocity of fluid at the head of the tool, which results in more efficient cooling and consequently the temperature along the cutting edge is decreased.