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Geothermal energy is a clean, abundant, and dependable energy source. Because the formation of a geothermal field is often closely linked to the distribution and development of granite, it is crucial to understand the regularity and formation mechanism of granite geothermal resources to advance the field of geothermal energy. Lancang County is located on the southern edge of the Lincang granite, and contains many hot springs. In this paper, we synthesize rock geochemistry, zircon U–Pb chronology, and other methods to interpret the genesis of granites in Lancang County and their geothermal formation patterns. The study area mainly comprises a Middle Triassic S-type granite with high contents of heat-producing elements. Zircon U–Pb dating results show that the intrusion time of the Lancang granite was 239 Ma. The granite is rich in light rare earth elements, depleted in heavy rare earth elements, and characterized by a negative Eu anomaly. The ɛHf values range from −20.3 to 13.6, indicating the presence of mantle material in the source area. Igneous rocks in Lancang County likely formed in the background of an active continental margin associated with the subduction of the Tethys Ocean to the east, which formed an intra-land orogeny. High contents of radioactive thermogenic elements in the granite, fracture development, and additional heat sources from metamorphic rocks combined to generate high-temperature geothermal resources in the study area. The hydrothermal geothermal model of the granite has the following characteristics: a near heat source, large drop, water storage in fractures, simultaneous geothermal influence in deep and shallow layers, and hot spring and geothermal distribution along deep and large faults, etc. The geothermal reservoirs in the study area are classified into four types: internal fissures in granite, granite paleo-weathering crust, tectonic nappe fractures, and sedimentary deposits associated with granite cooling collapse. These types are of great significance to the understanding of the formation of hydrothermal geothermal heat in this granite area.

China is tectonically composed of a series of plates and orogenic belts and has been influenced by the Pacific and Indian plates since the Late Paleozoic, forming a regular distribution of Mesozoic and Cenozoic granites. As an important source of geothermal energy, granite is the five elements of geothermal enrichment:geothermal sources; geothermal reservoirs; heat transmission; heat caprock; and heat preservation and it is possible to classify the types of geothermal resources in China according to their distribution in combination with neotectonic movements. China's geothermal energy can be divided into hydrothermal and hot dry rock types in basins and orogenic belts, respectively. Geothermal resources can be divided into hydrothermal, rock, magma, and hybrid geothermal types according to the heat carrier type. Basin geothermal resources are dominated by hydrothermal types, while geothermal energy in orogenic belts with granite includes both hydrothermal and hot dry rock types. Geothermal resources in China can be divided into 6 distinct geothermal regions and 13 subregions, of which the Southwest and Southeast China regions and the Qaidam-Qilian and Jiaoliao subregions in North China with Mesozoic and Cenozoic granites are the most favorable areas for high-temperature hydrothermal and hot dry rock sources. China has complex geological conditions, diverse types of geothermal resources, and broad prospects for development and utilization. Having performed extensive shallow hydrothermal geothermal development and utilization and completed various power generation tests, China's geothermal development and utilization is in a critical stage of transition from the direct utilization of shallow hydrothermal resources to high-temperature geothermal or hot dry rock power generation in middle and deep layers. Basic theoretical research, key technology breakthroughs, and policy incentives are the main issues that need to be addressed in the geothermal industry.

BACKGROUND: User-side distributed generation represented by distributed photovoltaic and distributed wind turbine has shown an expansion trend of decentralized construction and disordered access, which is difficult to satisfy the demand for large-scale exploitation and sustainable development of distributed generation under the low-carbon transformation vision of the power system. OBJECTIVES: To address the interest conflict and operation security problems caused by scaled distributed generation accessing the distribution network, this paper proposes the optimal planning method of user-side scaled distributed generation based on the Stackelberg game. METHODS: Firstly, a cluster planning and operation mode of distributed generation is established. Then, a prediction method for planning behavior of user-side distributed generation is proposed in order to predict whether users will adopt the self-build mode or the leasing site mode for distributed generation. Finally, in order to reveal the game relationship between the distribution network operator and the users in the allocation of distributed generation resources, a bi-level planning model for scaled distributed generation is established based on the Stackelberg game. RESULTS: The simulation results show that the revenue of the distribution network operator under the gaming model increases by 10.15% and 16.88% compared to the models of all users self-build distributed generation and all users leasing distributed generation site, respectively, while at the same time, individual users also realize different degrees of revenue increase. CONCLUSION: The case analysis validates the effectiveness of the proposed method in guiding the rational and efficient planning of user-side distributed generation.

The cracking of geopolymer caused by its brittleness characteristics could reduce the stability and durability of the building structure. Studying the cracking behavior of fiber-reinforced geopolymer composites (FRGCs) is important to evaluate the toughness strengthening of geopolymer. This paper presents a real-time study on the cracking characteristics of FRGCs under splitting tensile load based on high-speed digital image correlation (HDIC) technology. The splitting tensile test was conducted on the FRGC with different fiber content. The real-time variation of strain and displacement field during the splitting process was analyzed. The influence of fiber content on the mechanical properties and crack behavior of FRGCs was discussed. Considering the splitting strength and crack width, the optimal fiber content for FRGCs that satisfied the crack resistance requirement was proposed. The results show that the incorporation of fiber can delay the cracking time and reduce strain change during the splitting process. The splitting tensile strength and the deformation increase as fiber content increases, while the crack width decreases as fiber content increases. The FRGC with 2.0% fiber content can maintain a crack width smaller than 0.1 mm, which satisfies the crack resistance requirements of practical engineering for economic consideration.

As reversible fluorescent probes, HTP-1 and HTP-2 have favourable applications for the detection of Zn2+ and H2S. Herein, the impact of solvent on the excited-state intramolecular proton transfer (ESIPT) of HTP-1 and HTP-2 was comprehensively investigated. The obtained geometric parameters and infrared (IR) vibrational analysis associated with the intramolecular hydrogen bond (IHB) indicated that the strength of IHB for HTP-1 was weakened in the excited state. Moreover, structural torsion and almost no ICT behaviour indicated that the ESIPT process did not occur in HTP-1. Nevertheless, when the 7-nitro-1,2,3-benzoxadiazole (NBD) group replaced the H atom, the IHB strength of HTP-2 was enhanced after photoexcitation, which inhibited the twisting of tetraphenylethylene, thereby opening the ESIPT channel. Notably, hole-electron analysis and frontier molecular orbitals revealed that the charge decoupling effect was the reason for the fluorescence quenching of HTP-2. Furthermore, the potential energy curves (PECs) revealed that HTP-2 was more inclined to the ESIPT process in polar solvents than in nonpolar solvents. With a decrease in solvent polarity, it was more conducive to the ESIPT process. Our study systematically presents the ESIPT process and different detection mechanisms of the two reversible probe molecules regulated by solvent polarity, providing new insights into the design and development of novel fluorescent probes.

Abstract Background Busulfan (BU) is an alkylating agent used as a conditioning agent prior to hematopoietic stem cell (HSC) transplantation as it is known to be cytotoxic to host hematopoietic stem and progenitor cells. The susceptibility of HSCs to BU injury plays an important role in the myeloablative efficacy of BU. Different susceptibilities were demonstrated in genetically diverse (GD) mice in our preliminary research. Methods Three strains of GD mice with different susceptibilities to BU‐induced HSC injury were used for screening biological markers of HSC injury susceptibility in urine. The urine proteins were analyzed using liquid chromatography coupled with tandem mass spectrometry to screen for differentially expressed proteins. Screening for possible biomarkers based on differences in protein expression abundance was validated using enzyme‐linked immunoassay (ELISA). Results Functional analysis showed that the differential proteins were all involved in a series of biological pathways related to cellular senescence, apoptosis, and angiogenesis; whereas the differential proteins of the high‐susceptible strain were enriched for the regulation of bone marrow microenvironment pathways, those of low‐susceptible strain were enriched for the proapoptotic effect of GTPase pathways. Based on protein abundance differences, several urinary proteins that may be indicative of susceptibility were screened, and ELISA validation results showed that angiotensin‐converting enzyme may be a potential biomarker predicting HSC susceptibility for BU conditioning. Conclusions This study indicates that urinary protein levels can reflect differences in susceptibility to BU‐induced HSC injury. Using GD mice to construct genetic difference models will provide preclinical data for screening BU‐related biological markers.

Although significant progress has been made in the geological theory and exploration and development of shale gas in China, the research on the geological particularity and enrichment regularity associated with shale gas accumulation remains weak. With this in mind, we analyzed the shale gas accumulation patterns in China. The findings show that: (1) A variety of organic-rich shales were deposited in the continental margin-type marine and transitional environments during the Pre-Mesozoic period and the basin-type terrestrial environment during the Mesozoic and Cenozoic eras. (2) The basins dominated by Mesozoic and Cenozoic terrestrial sediments superimpose on the Pre-Mesozoic continental margin-type marine–or transitional-facies sediments. The former developed the terrestrial shales with large thickness, high organic matter abundance, new age, and low thermal maturity; meanwhile, the deep parts of the basins are favorable for shale gas enrichment. However, the latter preserves the shale with old age, high thermal maturity, and undergoing multiphase tectonic movements; and the tectonically stable regions are favorable for shale gas enrichment. (3) The aulacogens mainly formed in the Meso-Neoproterozoic, Sinian-Ordovician, and Devon-Triassic periods are favorable for marine organic-rich shale deposition; moreover, this type of shale and other types including transitional facies shales with favorable reservoir-forming assemblages, coal-measure shales in small and medium-sized basins, and low-medium mature shales affected by magma intrusion, have jointly constituted the various shale gas accumulation patterns in China. (4) Based on the drilling discoveries in China, shale gas accumulation patterns can be categorized into two types: tectonic-controlled and stratigraphic-controlled. The former is mainly related to structural features, whereas the latter is mainly related to the variation of lithology and strata. (5) Shale development and gas content are mainly affected and controlled by geological factors including sedimentation, diagenesis, and later tectonic movements. Favorable sedimentary environments, appropriate thermal maturity, good sealing capacity of caprock, and excellent structural preservation are the necessary conditions for shale gas enrichment.

Zearalenone (ZEA) has adverse effects on human and animal health, and finding effective strategies to combat its toxicity is essential. The probiotic Bacillus velezensis A2 shows various beneficial physiological functions, including the potential to combat fungal toxins. However, the detailed mechanism by which the Bacillus velezensis A2 strain achieves this protective effect is not yet fully revealed. This experiment was based on transcriptome data to study the protective mechanism of Bacillus velezensis A2 against ZEA-induced damage to IPEC-J2 cells. The experiment was divided into CON, A2, ZEA, and A2+ZEA groups. This research used an oxidation kit to measure oxidative damage indicators, the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) method to detect cell apoptosis, flow cytometry to determine the cell cycle, and transcriptome sequencing to screen and identify differentially expressed genes. In addition, gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were adopted to screen out relevant signaling pathways. Finally, to determine whether A2 can alleviate the damage caused by ZEA to cells, the genes and proteins involved in inflammation, cell apoptosis, cell cycles, and related pathways were validated using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot methods. Compared with the CON group, the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in the ZEA group increased significantly (p < 0.01), while the levels of antioxidant enzyme activity, total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), and catalase (CAT) decreased significantly (p < 0.01). Compared with the ZEA group, the A2+ZEA group showed a significant decrease in ROS and MDA levels (p < 0.01), while the levels of T-SOD, GSH-PX, T-AOC, and CAT increased significantly (p < 0.01). TUNEL and cell cycle results indicated that compared with the ZEA group, the A2+ZEA group demonstrated a significant decrease in the cell apoptosis rate (p < 0.01), and the cell cycle was restored. Combining transcriptome data, qRT-PCR, and Western blot, the results showed that compared with the CON group, the mRNA and protein expression levels of Wnt10 and β-catenin increased significantly (p < 0.01), while the expression level of FRZB decreased significantly (p < 0.01); compared with the ZEA group, the expression levels of these mRNA and proteins were reversed. Bacillus velezensis A2 can increase the antioxidant level, reduce inflammatory damage, decrease cell apoptosis, and correct the cell cycle when that damage is being caused by ZEA. The protective mechanism may be related to the regulation of the Wnt/FRZB cell/β-catenin signaling pathway.

To improve the detection sensitivity of neomycin (NEO) in milk, we produced a sensitive monoclonal antibody (mAb) against NEO and developed a lateral flow immunoassay based on amorphous carbon nanoparticles (ACNPs-LFA). First, we conjugated NEO to carrier protein to prepare mAbs. We obtained six mAbs: mAb 1C6, mAb 1D3, mAb 2D3, mAb 4D5, mAb 5D1, and mAb 5H1. We characterised the mAbs by indirect competitive enzyme-linked immunosorbent assay and selected the most sensitive mAb based on the half-maximal inhibitory concentration (IC50). We selected mAb 4D5 (IC50 = 0.15 ng/mL) for the development of LFA. MAb 4D5 was labelled with ACNPs (ACNPs-mAb 4D5) by electrostatic absorption. Under optimised conditions, 5.4 μg mAb 4D5 coupling with 1 mL ACNPs, NEO-OVA at concentration of 80 μg/mL, 3 μL ACNPs-mAb 4D5 were used to develop LFA. The cut-off value was 8 ng/mL. Therefore, our developed ACNPs-LFA is suitable for on-site detection of NEO residues.

As sandstone layers in thin interbedded section are difficult to identify, conventional model-driven seismic inversion and data-driven seismic prediction methods have low precision in predicting them. To solve this problem, a model-data-driven seismic AVO (amplitude variation with offset) inversion method based on a space-variant objective function has been worked out. In this method, zero delay cross-correlation function and F norm are used to establish objective function. Based on inverse distance weighting theory, change of the objective function is controlled according to the location of the target CDP (common depth point), to change the constraint weights of training samples, initial low-frequency models, and seismic data on the inversion. Hence, the proposed method can get high resolution and high-accuracy velocity and density from inversion of small sample data, and is suitable for identifying thin interbedded sand bodies. Tests with thin interbedded geological models show that the proposed method has high inversion accuracy and resolution for small sample data, and can identify sandstone and mudstone layers of about one-30th of the dominant wavelength thick. Tests on the field data of Lishui sag show that the inversion results of the proposed method have small relative error with well-log data, and can identify thin interbedded sandstone layers of about one-15th of the dominant wavelength thick with small sample data.

Accurate delineation of individual teeth and alveolar bones from dental cone-beam CT images is an essential step in digital dentistry for precision dental healthcare. Here, the authors present a deep learning system for efficient, precise, and fully automatic segmentation of real-patient CBCT images presenting highly variable appearances.

Lenses are an important part of modern optical systems. We propose metalenses with bifocal spots, which realizes the beam focusing with controllable intensity ratio and free deflection of the bifocal spots. The metalens consists of an array of titanium dioxide (TiO2) nanopillars, which can provide two different propagation phases for x-linear polarization (XLP) and y-linear polarization (YLP) incidence, respectively. Therefore, by precisely choosing the size of the nanopillars, it is possible to produce two different focal spots for the two orthogonal input polarized light. And the intensity of the two focal points can be adjusted by changing the polarization angle of the incident light. Superimposing the initial phase distribution of the metalens and the phase distribution of the beam deflector metasurface enables multi-dimensional adjustment of the two focal points and realizes the free deflection characteristics of the metalens. The deflection angle of the focal spot is close to the theoretical deflection angle. In addition, multiple superposition can produce more deflection angles or deflect the focus to a two-dimensional plane. The method of controlling the targeting phase of the metalens by superimposing additional phases gives us the ability to fully manipulate the phase and wavefront of the metalens, providing a new idea for the continuous angle change of future optical lenses.

Smart windows with high visible transmission can control the absorption or transmission spectrum of solar irradiation based on seasonal variations and personal preferences, allowing buildings to save energy. However, it is a considerable challenge to design a metasurface with high solar modulation ability (ΔAsol), integral luminous transmittance (Tlum), transmission light's color rendering index (Ra) and simple structure for smart windows. In this work, we design and optimize the asymmetric-structured multilayer and micro-nano array by applying the method of scanning parameters and fully-connected network methods. The optimization results show that ΔAsol and Tlum negatively correlate when the transmitted light of these two structures has a high Ra. This conclusion of designing high-performance asymmetric-structured metasurfaces provides essential guidance for designing future smart windows.

In this paper, we present a scheme for achieving broadband efficient beam splitting based on homogeneous ultra-thin metasurfaces, which is composed of an ultrathin dielectric spacer sandwiched between periodic arrays of identical rectangular metal resonators and an optically thick metal film. Based on this scheme, three beam splitters for incident wavelengths in the ultraviolet (UV), visible, and infrared (IR) are designed and investigated numerically. Although these beam splitters exhibit polarization-dependent optical responses, each one still has an operational band in which the conversion efficiency remains above 90 % for any polarization incidence. The operational band is respectively 250–299 nm, 478–574 nm, and 1411–1700 nm for these three metasurface-based beam splitters. Moreover, we propose a dual-band beam splitter and a four-channel beam splitter based on this metasurface with MIM configuration. The operational window of the dual-band beam splitter respectively locates in the visible and infrared regions.

Disturbance of bone homeostasis caused by Mycobacterium tuberculosis (Mtb) is a key clinical manifestation in spinal tuberculosis (TB). However, the complete mechanism of this process has not been established, and an effective treatment target does not exist. Increasing evidence shows that abnormal osteoclastogenesis triggered by an imbalance of the receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG) axis may play a key role in the disturbance of bone homeostasis. Previous studies reported that RANKL is strongly activated in patients with spinal TB; however, the OPG levels in these patients were not investigated in previous studies. In this study, we investigated the OPG levels in patients with spinal TB and the dysregulation of osteoblasts caused by Mtb infection. Inhibition of the Mce4a gene of Mtb by an antisense locked nucleic acid (LNA) gapmer (Mce4a-ASO) was also investigated. Analysis of the serum OPG levels in clinical samples showed that the OPG levels were significantly decreased in patients with spinal TB compared to those in the group of non-TB patients. The internalization of Mtb in osteoblasts, the known major source of OPG, was investigated using the green fluorescent protein (GFP)-labeled Mycobacterium strain H37Ra (H37RaGFP). The cell-associated fluorescence measurements showed that Mtb can efficiently enter osteoblast cells. In addition, Mtb infection caused a dose-dependent increase of the CD40 mRNA expression and cytokine (interleukin 6, IL-6) secretion in osteoblast cells. Ligation of CD40 by soluble CD154 reversed the increased secretion of IL-6. This means that the induced CD40 is functional. Considering that the interaction between CD154-expressing T lymphocytes and bone-forming osteoblast cells plays a pivotal role in bone homeostasis, the CD40 molecule might be a strong candidate for mediating the target for treatment of bone destruction in spinal TB. Additionally, we also found that Mce4a-ASO could dose-dependently inhibit the Mce4a gene of Mtb and reverse the decreased secretion of IL-6 and the impaired secretion of OPG caused by Mtb infection of osteoblast cells. Taken together, the current finding provides breakthrough ideas for the development of therapeutic agents for spinal TB.

TS-1 zeolite with desirable pore structure, an abundance of acidic sites, and good thermal stability promising as a support for the selective catalytic reduction of NO with NH3 (NH3-SCR). Herein, a series of Mn–Fe/TS-1 catalysts have been synthesized, adopting tetraethylenepentamine (TEPA) as a metal complexing agent using the one-pot hydrothermal method. The introduced TEPA can not only increase the loading of active components but also prompts the formation of a hierarchical structure through decreasing the size of TS-1 nanocrystals to produce intercrystalline mesopores during the hydrothermal crystallization process. The optimized Mn–Fe/TS-1(R-2) catalyst shows remarkable NH3-SCR performance. Moreover, it exhibits excellent resistance to H2O and SO2 at low temperatures. The characterization results indicate that Mn–Fe/TS-1(R-2) possesses abundant surface Mn4+ and Fe2+ and chemisorbed oxygen, strong reducibility, and a high Brønsted acid amount. For comparison, Mn–Fe/TiO2 displays a narrower active temperature window due to its poor thermostability.

The bound state in the continuum (BIC) has paved a new way to achieve excellent localization of the resonant mode coexisting with a continuous spectrum in the metasurface. Here, we propose an all-dielectric metasurface consisting of periodic pairs of asymmetric crosses that supports multiple Fano resonances. Due to the sufficient degrees of freedom in the unit cell, we displaced the vertical bars horizontally to introduce in-plane perturbation, doubling the unit cell structure. Dimerization directly resulted in the folding of the Brillouin zone in k space and transformed the BIC modes into quasi-BIC resonances. Then, simultaneous in-plane symmetry breaking was introduced in both the x and y directions to excite two more resonances. The physical mechanisms of these BIC modes were investigated by multipole decomposition of the scattering cross section and electromagnetic near-field analysis, confirming that they are governed by toroidal dipole (TD) modes and magnetic dipole (MD) modes. We also investigated the flexible tunability and evaluated the sensing performance of our proposed metasurface. Our work is promising for different applications requiring stable and tunable resonances, such as optical switching and biomolecule sensing.

Aflatoxin B1 (AFB1), ochratoxin A (OTA), and deoxynivalenol (DON) are the three mycotoxins that have received the most scholarly attention and have been tested most routinely in clinics. These mycotoxins not only suppress immune responses but also induce inflammation and even increase susceptibility to pathogens. Here, we comprehensively reviewed the determining factors for the bidirectional immunotoxicity of the three mycotoxins, their effects on pathogens, and their action mechanisms. The determining factors include mycotoxin exposure doses and times, as well as species, sex, and some immunologic stimulants. Moreover, mycotoxin exposure can affect the infection severity of some pathogens, including bacteria, viruses, and parasites. Their specific action mechanisms include three aspects: (1) mycotoxin exposure directly promotes the proliferation of pathogenic microorganisms; (2) mycotoxins produce toxicity, destroy the integrity of the mucosal barrier, and promote inflammatory response, thereby improving the susceptibility of the host; (3) mycotoxins reduce the activity of some specific immune cells and induce immune suppression, resulting in reduced host resistance. The present review will provide a scientific basis for the control of these three mycotoxins and also provide a reference for research on the causes of increased subclinical infections.

The nonlinear characteristics of bolted connections are of significant importance for analyzing the mechanical performance of structures. The Iwan model is well-known and has been widely applied; its limitation is that it is not convenient for complex structures with multiple bolted connections. To simplify the modeling process, a material with the force-displacement characteristics of the Iwan model is proposed and applied to the bolted connection region, which can convert the nonlinearity of the bolted connection into the nonlinearity of the material. The constitutive relation of the proposed Iwan-based material is determined by the force-displacement equation of the bolted connection under load and the elastic-plastic hypothesis. The proposed Iwan-based material is implemented using the UMAT subroutine of ABAQUS, and the properties of the Iwan-based material are assigned to a solid finite element for an equivalent modeling of bolted connections. Through comparisons with the s imul ation results of the AIBE, the feasibility of the equivalent modeling method for the force-displacement relationship of the original Iwan model is verified, and through comparisons with the simulation results and experimental results of a detailed 3D FE model of the bolted connection, the universality of the equivalent modeling method is verified. The results show that the equivalent modeling method can well restore the statics characteristics of bolted structures under cyclic loading and can be applied to complex combined structures. The method is more convenient for establishing the finite element model of bolted connections and has more flexibility in adjusting parameters than traditional methods.

Aflatoxin B1 (AFB1), one of the most common environmental mycotoxin contaminations in food and feed, poses significant threats to human and animal health. Our previous study indicated that even non-toxic AFB1 concentrations could promote influenza virus replication and induce influenza virus-infected alveolar macrophages polarizing from M1 (immunostimulatory phenotype) to M2 (immunosuppressive phenotype) over time. However, whether AFB1 promotes influenza replication via modulating the polarization of alveolar macrophages is unknown. Here, we specifically depleted alveolar macrophages using clodronate-containing liposomes in swine influenza virus (SIV)-infected mice to explore the mechanism the promotion of SIV replication by AFB1. The results show that the depletion of alveolar macrophages significantly alleviated the AFB1-induced weight loss, inflammatory responses, and lung and immune organ damage of the SIV-infected mice after 14 days and greatly diminished the AFB1-promoted SIV replication. In contrast, the depletion of alveolar macrophages did not alleviate the AFB1-induced weight loss, and lung and immune organ damage of the SIV-infected mice after 28 days and slightly diminished the AFB1-promoted SIV replication. Collectively, the data indicate that alveolar macrophages play a crucial role the promotion of SIV infection by AFB1 in the early rather than late stage, and AFB1 can promote SIV replication by inducing alveolar macrophages to polarize towards M1 macrophages. This research provides novel targets for reducing the risk of AFB1-promoted influenza virus infection.

To accurately estimate the effect of driving conditions on vehicle emissions, an on-road light-duty vehicle emission platform was established based on OEM-2100TM, and each second data of mass emission rate corresponding to the driving conditions were obtained through an on-road test. The mass emission rate was closely related to the velocity and acceleration in real-world driving. This study shows that a high velocity and acceleration led to high real-world emissions. The vehicle emissions were the minimum when the velocity ranged from 30 to 50 km/h and the acceleration was less than 0.5 m/s2. Microscopic emission models were established based the on-road test, and single regression models were constructed based on velocity and acceleration separately. Binary regression and neural network models were established based on the joint distribution of velocity and acceleration. Comparative analysis of the accuracy of prediction and evaluation under different emission models, total error, second-based error, related coefficient, and sum of squared error were considered as evaluation indexes to validate different models. The results show that the three established emission models can be used to make relatively accurate prediction of vehicle emission on actual roads. The velocity regression model can be easily combined with traffic simulation models because of its simple parameters. However, the application of neural network model is limited by a complex coefficient matrix. First published online 19 March 2020

EHB (electro-hydraulic brake system) can provide active and decoupled brake for electric intelligent vehicles. However, modelling and control of automotive electro-hydraulic brake systems are always challenging due to the complex and highly nonlinear dynamic characteristics of the braking process. In this paper, a nonlinear backstepping control algorithm for EHB based on the bond graph model is introduced. A nonlinear, single-wheel brake system model is constructed using the bond graph method, in which the capacitive effect of the hydraulic fluid and the damping and inertia effects of calipers are considered. Based on this nonlinear model, a backstepping controller with good robustness is designed, and the control signals of the inlet and outlet valves are described by a unified expression. Moreover, the effects of the controller parameters on brake-pressure control are discussed in details, and suitable design parameters are chosen. Finally, the proposed algorithm is verified by the simulation and hardware-in-the-loop tests. The results show that valves are properly regulated by the backstepping controller, and the brake pressure follows the desired value rapidly and accurately.

Porcine circovirus type 2 (PCV2) is the primary pathogen of porcine circovirus diseases and porcine circovirus associated diseases. Immunization with a vaccine is considered an effective measure to control these diseases. However, it is still unknown whether PCV2 vaccines have protective immune responses on the animals infected with swine influenza virus (SIV), a pandemic virus in swine herds. In this study, we first compared the effects of 2 different PCV2 vaccines on normal mice and SIV-infected mice, respectively. The results showed that these two vaccines had protective immune responses in normal mice, and the subunit vaccine (vaccine S) had better effects. However, the inactivated vaccine (vaccine I) instead of vaccine S exhibited more immune responses in the SIV-infected mice. SIV infection significantly decreased the immune responses of vaccine S in varying aspects including decreased PCV2 antibody levels and increased PCV2 replication. Mechanistically, further studies showed that SIV infection increased IL-10 expression and M2 macrophage percentage, but decreased TNF-α expression and M1 macrophage percentage in the mice immunized with vaccine S; on the contrary, macrophage depleting by using clodronate-containing liposomes significantly alleviated the SIV infection-induced decrease in the protective immune responses of vaccine S against PCV2. This study indicates that SIV infection decreases the protective immune responses of vaccine S against PCV2. The macrophage polarization induced by SIV infection might facilitate decreased immune responses to vaccine S, which provides new insight into vaccine evaluation and a reference for the analysis of immunization failure.

In order to improve the dynamic balancing accuracy of the micromotor armature, a method of V-shaped milling based on a discrete vector model for unbalance correction is proposed. The discrete vector model is fitted according to the parameters of the milling cutter and rotor, and then all the unit unbalance vectors in the discrete vector model are added to the milling center. The numerical relationship between the milling depth and the removal of the mass unbalance vector is obtained, and the accuracy of the model is verified via comparison with the data of the simulation experiments. The complexity of the integral formula of the numerical milling model makes it difficult to apply in practice. The discrete vector model does not require integration of the numerical formula and only considers the milling area as being composed of countless discrete blocks, which greatly simplifies the process of solving the unbalance vector. In view of the different thicknesses of the tooth surface of the armature, in order to avoid damage to the armature during milling, the unbalanced vector is decomposed at the center of the tooth surface by force decomposition. The experimental results show that this proposed method can effectively improve the dynamic balancing accuracy of the micromotor armature.

Three-dimensional subcooled flow boiling of R134a in a horizontal tube was simulated by a VOF (volume of fluid) model combined with the level set method. Bubble characteristics were explored at heat flux of 0.3 MW/m2, inlet subcooling of 3 K, and inlet velocity of 0.4 m/s. It was observed that five representative bubbles occurred in subcooled flow boiling, including sliding bubble, coalescing bubble, non-departed bubble, bouncing bubble, and continuous-boiling bubble. The results showed that the bubble radial velocity was an important factor of bubble departure after a sliding process. Moreover, the effect of heat flux, inlet velocity, and inlet subcooling on bubble departure diameter were investigated. The departure diameter increased with increasing inlet velocity from 0.2 to 0.4 m/s and heat flux from 0.2 to 0.4 MW/m2, while diameter decreased with inlet subcooling from 3 to 10 K. Finally, based on the influence of heat flux, inlet velocity, and inlet subcooling on average departure diameter of the bubble except the coalescing bubble, a model was proposed to predict the average departure diameter. The deviation of the model was within 5%.

Microbial transformation is a vital mechanism to internally treat nitrogen (N) within bioretention cells (BRCs); nitrifying and denitrifying microorganisms are the main drivers of permanent nitrogen removal. The limited research of the characteristics of nitrifying and denitrifying microbes in different layers during dry periods has prevented further understanding of nitrogen behavior in bioretention cells. In this paper, high-throughput sequencing technology and qPCR were used to analyze the microbial community and the abundance of six functional genes in soil and water samples of a layered BRC. This study found that the microbial community structure of the gravel layer was distinguished from that of the other three layers. With the extension in the dry period, the amount of microbial species shared by all four layers increased, showing a convergent succession of microorganisms. The nitrification and denitrification functional genes mainly existed in the upper layer of the bioretention cell; in addition, the abundance of the functional genes in the sand layer increased after rainfall and peaked at about 24–48 h, after which the abundance decreased and became steady. Correlation analysis indicated that the abundance of nitrification and denitrification functional genes was significantly affected by TOC, ammonia nitrogen concentration and nitrate nitrogen concentration.

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is regarded as the bridge between bio-refinery and the traditional petroleum industry. In recent years, non-precious metal-based catalysts for LA hydrogenation to GVL have attracted much attention owing to their low cost and high efficiency. Metal-involving catalytic hydrogenation of LA is the rate-determining step in the production of GVL, and thus the active site structure of metal-based catalysts governs the overall catalytic performance. Herein, non-precious metal-based catalytic systems including Cu, Zr, Co and Ni are classified into single metal (M = Ni, Cu and Co), bimetallic (Cu–Ni, Ag–Ni, Cu–Co and Co–Zn), metal-heteroatom (M–O and M–N) and heterostructured (CePO4/CoP2 and Ni/NiO) catalysts according to the type of active site structure. The correlation of active site structure with catalytic activity is discussed emphatically, and its relationship with stability is also referred to in terms of strong metal–support interaction, bimetallic synergism, core–shell structure and heterojunction. This review provides an important guide for the rational design of high-performance non-precious metal-based catalysts for the LA-to-GVL process.

Oxygen exposure is unavoidable and the impact of its management during the post-fermentation stage (PFS) on dry red wine is poorly investigated. This study was dedicated to the variation of acetaldehyde, color and phenolics of Cabernet Sauvignon dry red wine during five discontinuous oxidation cycles of four levels of controlled oxygen supply, which were carried out to simulate probable oxidation during the PFS. Free SO2 disappeared after the first, second and third oxidation cycles in wines with high, medium and low levels of oxygen exposure severally, but subsequent oxygen exposure below or equal to 2 mg O2/L per cycle had little effect while 3–3.9 mg O2/L per cycle dramatically facilitated acetaldehyde accumulation, which was accompanied by an enormous variation in color and pigments, especially when total oxygen consumption was above 10 mg/L. The utilization of clustered heatmap and partial least square regression demonstrated the feasibility of characterization of wine oxidation degree using the chemical parameters measured by UV-spectrophotometry. Oxygen exposure during the PFS should be emphatically controlled, and chemical indexes determined by the UV–spectrophotometric method can be used for a scientific and effective description of wine oxidation degree.

Metasurfaces with both multifunctionality and tunability hold great application potential in next-generation optical devices. In this paper, we propose a stretchable metasurface composed of arrays of identical dielectric rectangular resonators embedded in the polydimethylsiloxane (PDMS) substrate. It is shown that the metasurface possesses three functions at the operating wavelength of 532 nm. The switching of functions can be implemented by changing the period Px of the metasurface, induced by stretching the PDMS substrate along the x-direction. When the period Px is less than the operating wavelength of 532 nm, the behavior of metasurface can switch between transmissive window and reflective mirror. When the period Px of the metasurface varies from 532 nm to 700 nm, the metasurface act as a dynamic equal-power beam splitter with conversion efficiency higher than 90%, and the corresponding splitting angle can be adjusted from 90° to around 49.5°. Moreover, we achieve the switching of transmissive window/reflective mirror/split-ratio-variable splitter based on the metasurface consisting of arrays of identical L-shaped resonators embedded in the PDMS substrate.

Bolted connections have been widely applied in engineering structures, loosening will happen when bolted connections are subjected to continuous cyclic load, and a significant rotation between the nut and the bolt can be observed. Combining deep learning with machine vision, a bolt loosening detection method based on the fifth version of You Only Look Once (YOLOv5) is proposed, and the rotation of the nut is identified to detect the bolt loosening. Two different circular markers are added to the bolt and the nut separately, and then YOLOv5 is used to identify the circular markers, and the rotation angle of the nut against the bolt is calculated according to the center coordinate of each predicted box. A bolted connection structure is adopted to illustrate the effectiveness of the method. First, 200 images containing bolts and circular markers are collected to make the dataset, which is divided into a training set, verification set and test set. Second, YOLOv5 is used to train the model; the precision rate and recall rate are respectively 99.8% and 100%. Finally, the robustness of the proposed method in different shooting environments is verified by changing the shooting distance, shooting angle and light condition. When using this method to detect the bolt loosening angle, the minimum identifiable angle is 1°, and the maximum detection error is 5.91% when the camera is tilted 45°. The experimental results show that the proposed method can detect the loosening angle of the bolted connection with high accuracy; especially, the tiny angle of bolt loosening can be identified. Even under some difficult shooting conditions, the method still works. The early stage of bolt loosening can be detected by measuring the rotation angle of the nut against the bolt.

The effects of insulin-like growth factor binding protein 2 (IGFBP2) on the expression of fatty acid synthesis regulators and triglyceride production were investigated in primary cultured chicken hepatocytes. The full-length chicken IGFBP2 coding region was synthesized by overlap extension PCR and cloned into the pcDNA3.1 vector. An in situ digestion method was used to prepare the chicken hepatocytes. Primary chicken hepatocytes were maintained in monolayer culture. Real-time PCR was used to detect changes in the expression of IGFBP2, PPARG, IGF1, IGF1R, APOAI, and LFABP, after the overexpression of IGFBP2 in chicken hepatocytes. Triglyceride production and glucose content were also evaluated using triglyceride and glucose analysis methods. The expression level of IGFBP2 increased after transfection of the IGFBP2-containing vector. The expression levels of PPARG, IGF1, and IGF1R also increased in cultured chicken hepatocytes after the overexpression of IGFBP2, whereas the expression of LFABP and APOAI decreased. Triglyceride production in primary cultured chicken hepatocytes increased after the overexpression of IGFBP2. These results suggest that IGFBP2 is involved in lipogenesis, increasing both the expression of fatty acid synthesis regulators, and triglyceride production in primary cultured chicken hepatocytes.

Acetaldehyde is a critical reactant on modifying the phenolic profile during red wine aging, suggesting that the acetaldehyde-mediated condensation can be responsible for the variation of antioxidant activity during the aging of this beverage. The present study employs exogenous acetaldehyde at six levels of treatment (7.86 ± 0.10–259.02 ± 4.95 mg/L) before the bottle aging of Merlot wines to encourage phenolic modification. Acetaldehyde and antioxidant activity of wine were evaluated at 0, 15, 30, 45, 60 and 75 days of storage, while monomeric and polymeric phenolics were analyzed at 0, 30 and 75 days of storage. The loss of acetaldehyde was fitted to a first-order reaction model, the rate constant (k) demonstrated that different chemical reaction happened in wines containing a different initial acetaldehyde. The disappearance of monomeric phenolics and the formation of polymeric phenolics induced by acetaldehyde could be divided into two phases, the antioxidant activity of wine did not alter significantly in the first phase, although most monomeric phenolics vanished, but the second phase would dramatically reduce the antioxidant activity of wine. Furthermore, a higher level of acetaldehyde could shorten the reaction time of the first phase. These results indicate that careful vinification handling aiming at controlling the acetaldehyde allows one to maintain prolonged biological activity during wine aging.

Perilipin1 (PLIN1), the most abundant lipid droplet (LD)-associated protein, plays a vital role in regulating lipid storage and breakdown in adipocytes. Recently, we found that the overexpression of PLIN1 promotes chicken preadipocyte lipid accumulation. However, the mechanisms by which transcription of the chicken PLIN1 gene is regulated remain unknown. In this study, we investigated the role of retinoid X receptor α (RXRα) in transcription of the chicken PLIN1 gene. Notably, reporter gene and expression assays showed that RXRα activates transcription of the chicken PLIN1 gene in a PPARγ-independent manner. Furthermore, promoter deletion and electrophoretic mobility shift assay (EMSA) analysis revealed that the chicken PLIN1 gene promoter region (-774/-785) contains an RXRα-binding site. Further study demonstrated that RXRα overexpression promotes differentiation of an immortalized chicken preadipocyte cell line (ICP1), causing a concomitant increase in PLIN1 transcripts. Taken together, our results show for the first time that RXRα activates transcription of the chicken PLIN1 gene in a PPARγ-independent manner, which might be at least in part responsible for RXRα-induced adipogenesis.

Background/Aims: Swine influenza virus (SIV) is a major pathogen of both animals and humans. Afatoxin B1 (AFB1) is one of the most common mycotoxins in feed and food. However, the central contribution of AFB1 to SIV infection remains unclear. Methods: Here, TCID50 assays, fluorescence-based quantitative real-time PCR, western blotting, immunofluorescence staining, histopathological examination, flow cytometry and scanning electron microscopy were performed to investigate the involvement and underlying mechanism of AFB1 in SIV infection in vivo and in vitro using mouse models and porcine alveolar macrophage (PAM) models, respectively. Results: The in vivo study showed that low levels of AFB1 promoted SIV infection and increased its severity, as demonstrated by the increased mRNA expression of viral matrix protein (M); by the increased protein expression of nucleoprotein (NP), matrix protein 1 and ion channel protein; and by animal weight loss, lung index and lung histologic damage. In addition, the increased occurrence of SIV infection accompanied by increases in the level of IL-10 in sera and lungs, in the spleen index and in the number of CD206-positive mouse alveolar macrophages but decreases in the level of TNF-α in sera and lungs, in the thymus index and in the number of CD80-positive mouse alveolar macrophages was observed in SIV-infected mice after low-level AFB1 exposure. The in vitro study showed that low concentrations of AFB1 promoted SIV infection, as demonstrated by the increases in viral titers and viral M mRNA and NP expression levels in SIV-infected PAMs as well as by the number of cells positive for NP protein expression. Furthermore, AFB1 promoted the polarization of SIV-infected PAMs to the M1 phenotype at 8 hpi and to the M2 phenotype at 24 hpi, as measured by the increases in IL-10 expression and in the number of CD206-positive PAMs as well as by the morphological changes observed by scanning electron microscopy. The administration of the immune stimulant lipopolysaccharide (LPS) reversed the switch in PAM polarization from M2 to M1 and thereby counteracted the promotion of influenza virus infection induced by AFB1. Conclusion: Our results are the first to confirm that low-level exposure to AFB1 promotes SIV infection and modulates a switch in macrophage polarization from M1 to M2. The work reported here provides important data that point to a role for AFB1 in SIV infection, and it opens a new field of study.

N-doped mesoporous carbons, NMCs, have attracted intensive attention recently and have shown potential applications in various scientific fields including catalysis and energy conversion/storage. Via modification with foreign N elements and construction of mesoporous structures for NMCs, their electronic and spin structure, as well as their porosity can be greatly tailored. And the resultant electron-donor property, surface wettability, conductivity, ion/molecular transfer and reactivity are changed accordingly. In this review, we will summarize the recent research progress of these metal-free NMCs, with an emphasis on their synthesis and performance, especially for their synthetic strategy and catalytic properties toward oxygen and nitro compound reductions, as well as their electrochemical properties as electrode materials for lithium-ion/sulfur batteries and supercapacitors. We hope for future developments, such as controlling doping methods more precisely, generating more active sites by N-doping, and finding wider applications of NMCs in other fields.

Aflatoxin B1 (AFB1), which alters immune responses to mammals, is one of the most common mycotoxins in feeds and food. Swine influenza virus (SIV) is a major pathogen of both animals and humans. However, there have been few studies about the relationship between AFB1 exposure and SIV replication. Here, for the first time, we investigated the involvement of AFB1 in SIV replication in vitro and in vivo and explored the underlying mechanism using multiple cell lines and mouse models. In vitro studies demonstrated that low concentrations of AFB1 (0.01–0.25 μg/ml) markedly promoted SIV replication as revealed by increased viral titers and matrix protein (M) mRNA and nucleoprotein (NP) levels in MDCK cells, A549 cells and PAMs. In vivo studies showed that 10–40 μg/kg of AFB1 exacerbated SIV infection in mice as illustrated by significantly higher lung virus titers, viral M mRNA levels, NP levels, lung indexes and more severe lung damage. Further study showed that AFB1 upregulated TLR4, but not other TLRs, in SIV-infected PAMs. Moreover, AFB1 activated TLR4 signaling as demonstrated by the increases of phosphorylated NFκB p65 and TNF-α release in PAMs and mice. In contrast, TLR4 knockdown or the use of BAY 11-7082, a specific inhibitor of NFκB, blocked the AFB1-promoted SIV replication and inflammatory responses in PAMs. Furthermore, a TLR4-specific antagonist, TAK242, and TLR4 knockout both attenuated the AFB1-promoted SIV replication, inflammation and lung damage in mice. We therefore conclude that AFB1 exposure aggravates SIV replication, inflammation and lung damage by activating TLR4-NFκB signaling.

Pore-fluid identification is one of the key technologies in seismic exploration. Fluid indicators play important roles in pore-fluid identification. For sandstone reservoirs, the effective pore-fluid bulk modulus is more susceptible to pore-fluid than other fluid indicators. AVO (amplitude variation with offset) inversion is an effective way to obtain fluid indicators from seismic data directly. Nevertheless, current methods lack a high-order AVO equation for a direct, effective pore-fluid bulk modulus inversion. Therefore, based on the Zoeppritz equations and Biot−Gassmann theory, we derived a high-order P-wave AVO approximation for an effective pore-fluid bulk modulus. Series reversion and Bayesian theory were introduced to establish a direct non-linear P-wave AVO inversion method. By adopting this method, the effective pore-fluid bulk modulus, porosity, and density can be inverted directly from seismic data. Numerical simulation results demonstrate the precision of our proposed method. Model and field data evaluations show that our method is stable and feasible.

The tribological properties of Ni3Si alloy were studied at high temperatures. The effect of the addition of Ti was also analyzed. The surface composition was analyzed by Raman spectroscopy. The results showed that the friction coefficient decreased with the increasing temperature, and the wear rate changed slightly from 25 to 400 °C. However, the wear resistance of the alloys decreased sharply at 600 °C, and this was due to the decrease of the high-temperature strength and the severe oxidation of the alloys. Although the oxidation resistance of Ni3Si alloy decreased with Ti addition, the tribological property was improved by the addition of Ti. The Ni3Si alloy with 5% Ti addition had the best wear resistance at high temperatures as compared to pure Ni3Si alloy and with 10% Ti addition, and the wear rates of the alloys were in the order of magnitude of 10−5 mm3/Nm. With the increase of temperature, the wear mechanism of pure Ni3Si alloy transformed from abrasive wear to oxidation wear. As the Ti content increased, the wear mechanisms of the alloys changed from abrasive wear to fatigue wear at low temperature, and oxidation wear and fatigue wear at high temperature.

Keeping good conductivity at high stretching strain is one of the main requirements for the fabrication of flexible electronic devices. The elastic nature of siloxane-based elastomers enables many innovative designs in wearable sensor devices and non-invasive insertion instruments, including skin-like tactile sensors. Over the last few years, polydimethylsiloxane (PDMS) thin films have been widely used as the substrates in the fabrication of flexible electronic devices due to their good elasticity and outstanding biocompatibility. However, these kind of thin films usually suffer poor resistance to tearing and insufficient compliance to curved surfaces, which limits their applications. Currently no three-dimensionally mountable tactile sensor arrays have been reported commercially available. In this work, we developed a kind of mechanically compliant skin-like conductive thin film by patterning silver nano wire traces in strip-style on Dragon Skin® (DS) substrates instead of PDMS. High cross- link quality was achieved then. To further improve the conductivity, a thin gold layer was coated onto the silver nanowires (AgNWs) strips. Four different gold deposition routines have been designed and investigated by using different E-beam and spin coating processing methods. Owning to the intrinsically outstanding physical property of the Dragon Skin material and the uniform embedment built in the gold deposition processes, the DS/AgNWs thin films showed convincible advantages over PDMS/AgNWs thin films in both mechanical capability and conductive stability. Through experimental tests, the DS/AgNWs electrode thin films were proven to be able to maintain high conductivity following repeated linear deformations.

Since the introduction of vaccines, the impact of vaccinations has been immeasurable. Under the current immunization guidelines, infants receive the first of their routine infant vaccinations at 2 months of age. While the benefits of routine infant vaccinations in premature infants have been demonstrated, there is relatively little data on the dosing of these vaccines in premature infants. The medical records of two premature infants who developed intramuscular abscesses after receiving their routine infant vaccinations were reviewed. Both patients developed pain in the area of the injection after receiving their vaccinations. Magnetic resonance imaging findings confirmed the formation of an abscess. No other causes of abscess formation were observed. Both patients required surgical intervention and were treated with a course of antibiotics. To our knowledge, this is the first case report to suggest routine vaccinations as a potential cause of abscess formation in premature infants.

BACKGROUND:The oriental river prawn (Macrobrachium nipponense) is the most prevalent aquaculture species in China. The sexual precocity in this species has received considerable attention in recent years because more and more individuals matured at a small size, which devalues the commercial production. In this study, we developed deep-coverage transcriptomic sequencing data for the ovaries of sexually precocious and normal sexually mature M. nipponense using next-generation RNA sequencing technology and attempted to provide the first insight into the molecular regulatory mechanism of sexual precocity in this species. RESULTS:A total of 63,336 unigenes were produced from the ovarian cDNA libraries of sexually precocious and normal sexually mature M. nipponense using Illumina HiSeq 2500 platform. Through BLASTX searches against the NR, STRING, Pfam, Swissprot and KEGG databases, 15,134 unigenes were annotated, accounting for 23.89% of the total unigenes. 5,195 and 3,227 matched unigenes were categorized by GO and COG analysis respectively. 15,908 unigenes were consequently mapped into 332 KEGG pathways, and many reproduction-related pathways and genes were identified. Moreover, 26,008 SSRs were identified from 18,133 unigenes. 80,529 and 80,516 SNPs were yielded from ovarian libraries of sexually precocious and normal sexually mature prawn, respectively, and 29,851 potential SNPs between these two groups were also predicted. After comparing the ovarian libraries of sexually precocious and normal sexually mature prawn, 549 differentially expressed genes (DEGs) and 9 key DEGs that may be related to sexual precocity of M. nipponense were identified. 20 DEGs were selected for validation by quantitative real-time PCR (QPCR) and 19 DEGs show consistent expression between QPCR and RNAseq-based differential expression analysis datasets. CONCLUSION:This is the first report on the large-scale RNA sequencing of ovaries of sexually precocious and normal sexually mature M. nipponense. The annotated transcriptome data will provide fundamental support for future research into the reproduction biology of M. nipponense. The large number of candidate SNPs and SSRs detected in this study could be used as genetic markers for population genetics and functional genomics in this species. More importantly, many DEGs, especially nine key DEGs between sexually precocious and normal sexually mature prawns were identified, which will dramatically improve understanding of molecular regulatory mechanism of sexual precocity of this species.

Three-dimensional B-rep is often used to convey product models in computer-aided design, computer-aided engineering, computer-aided process planning, and computer-aided manufacturing systems. Meaningful shape features need to be recognized from the B-rep models for product re-design and manufacturing. In this article, a novel hint-based reusable shape feature recognition approach is presented. Its core objectives include (1) definition and classification of isolated generic shape features by analyzing the shape variation or hint for a Boolean operation in computer-aided design modeling; (2) recognition algorithm for isolated generic shape features by detecting such hints or shape variations for each kind of generic shape feature; and (3) recognition of hybrid generic shape features for complex parts by detecting containing, fusing, and intersecting relationships among available generic shape features. Finally, three engineering parts are used as examples to validate the capabilities of the presented approach.