Rapid production of COVID-19 subunit vaccine candidates and their immunogenicity evaluation in pigs.

The emergence of various variants of concern (VOCs) necessitates the development of more efficient vaccines for COVID-19. In this study, we established a rapid and robust production platform for a novel subunit vaccine candidate based on eukaryotic HEK-293 T cells. The immunogenicity of the vaccine candidate was evaluated in pigs. The results demonstrated that the pseudovirus neutralizing antibody (pNAb) titers reached 7751 and 306 for the SARS-CoV-2 Delta and Omicron variants, respectively, after the first boost. Subsequently, pNAb titers further increased to 10,201 and 1350, respectively, after the second boost. Additionally, ELISPOT analysis revealed a robust T-cell response characterized by IFN-γ (171 SFCs/106 cells) and IL-2 (101 SFCs/106 cells) production. Our study demonstrates that a vaccine candidate based on the Delta variant spike protein may provide strong and broad protection against the prototype SARS-CoV-2 and VOCs. Moreover, the strategy for the efficient and stable expression of recombinant proteins utilizing HEK-293 T cells can be employed as a universal platform for future vaccine development.

Synergistic enhancement of chemisorption and catalytic conversion in lithium-sulfur batteries via Co3Fe7/Co5.47N separator mediator.

Lithium-sulfur batteries (LSBs) show considerable potential in next-generation high performance batteries, but the heavy shuttle effect and sluggish redox kinetics of polysulfide hinder their further applications. In this paper, to address these shortcomings of LSBs, Co3Fe7/Co5.47N heterostructure were prepared and constructed from their Fe-Co Prussian blue analogue precursors under the condition of high temperature pyrolysis. The obtained Co3Fe7/Co5.47N display excellent immobilization-diffusion-conversion performance for polysulfides by synergistic effect in successfully hindering the shuttle effect of polysulfides. When the Co3Fe7/Co5.47N heterostructure were applied to modify the commercial polypropylene (PP) separator, the batteries displayed fantastic rate capacity and cycling stability. Specifically, the Co3Fe7/Co5.47N-PP batteries exhibit an extremely satisfactory initial specific capacity of 1430 m Ah/g at 0.5C, wonderful rate capacity of around 780 m Ah/g at 3C and superior per cycle decaying rate of 0.08 % for 500 cycles at 0.5C. When the current density reaches to 2C, the batteries still exhibit 501 m Ah/g after 900 cycles with 0.015 % per cycle decay rate. Besides, even in the high loading of sulfur (3.0 mg cm-2) at 0.5C, the superior cycling stability (0.075 % per cycle decay rate after 200 cycles) and high specific capacity (741 mAh/g after 200 cycles) can still be performed. Thus, this work provides a facile method for high-powered and long-life Li-S batteries with eminent entrapping-conversion processes of polysulfides.

SMSP Mainlobe Jamming Suppression with FDA-MIMO Radar Based on FastICA Algorithm.

In the electronic warfare environment, the performance of ground-based radar target search is seriously degraded due to the existence of smeared spectrum (SMSP) jamming. SMSP jamming is generated by the self-defense jammer on the platform, playing an important role in electronic warfare, making traditional radars based on linear frequency modulation (LFM) waveforms face great challenges in searching for targets. To solve this problem, an SMSP mainlobe jamming suppression method based on a frequency diverse array (FDA) multiple-input multiple-output (MIMO) radar is proposed. The proposed method first uses the maximum entropy algorithm to estimate the target angle and eliminate the interference signals from the sidelobe. Then, the range-angle dependence of the FDA-MIMO radar signal is utilized, and the blind source separation (BSS) algorithm is used to separate the mainlobe interference signal and the target signal, avoiding the impact of mainlobe interference on target search. The simulation verifies that the target echo signal can be effectively separated, the similarity coefficient can reach more than 90% and the detection probability of the radar is significantly enhanced at a low signal-to-noise ratio.

Synergistic catalytic conversion and chemisorption of polysulfides from Fe/Fe3C/FeN0.0324 nanocubes modified separator for advanced Li-S batteries.

Lithium sulfur batteries (LSBs) have been considered as one of the most promising options for next generation high-performance batteries. However, the heavy shuttle effect and inferior redox conversion during the charge/discharge processes of the batteries have greatly hindered their further applications. In this study, to address these disadvantages of LSBs, Fe/Fe3C/FeN0.0324 heterostructured nanocubes were designed and prepared through high temperature carbonization process using Prussian blue precursor. Then the Fe/Fe3C/FeN0.0324 nanocubes were used to modify the commercial polypropylene (PP) separator, which can greatly catalyze the redox transformation of polysulfides and provide sufficient active sites for chemisorption. As result, the modified separator endowed LSBs with excellent rate capacity and cycle stability, delivering a high-capacity of 1025 mAh/g at 0.5 C with nearly 100% coulombic efficiency. It also displayed a superb cycling performance with a per-cycle capacity attenuation rate of 0.09% after 300 cycles. When the current density increased to 1 C with the S loading of 1.73 mg cm-2, Fe/Fe3C/FeN0.0324-PP separator presented a satisfactory capacity decay rate of 0.05% per cycle after 1000 cycles. Besides, it also presented outstanding electrochemical performance even at high sulfur loading of 4.5 mg cm-2. This work has provided a new avenue for the design of nanomaterials with synergistic effect of catalytic conversion and chemisorption of polysulfides for the promotion of high-performance Li-S batteries.

EM-Gaze: eye context correlation and metric learning for gaze estimation.

In recent years, deep learning techniques have been used to estimate gaze-a significant task in computer vision and human-computer interaction. Previous studies have made significant achievements in predicting 2D or 3D gazes from monocular face images. This study presents a deep neural network for 2D gaze estimation on mobile devices. It achieves state-of-the-art 2D gaze point regression error, while significantly improving gaze classification error on quadrant divisions of the display. To this end, an efficient attention-based module that correlates and fuses the left and right eye contextual features is first proposed to improve gaze point regression performance. Subsequently, through a unified perspective for gaze estimation, metric learning for gaze classification on quadrant divisions is incorporated as additional supervision. Consequently, both gaze point regression and quadrant classification performances are improved. The experiments demonstrate that the proposed method outperforms existing gaze-estimation methods on the GazeCapture and MPIIFaceGaze datasets.

Hierarchical SiC-Graphene Composite Aerogel-Supported Ni-Mo-S Nanosheets for Efficient pH-Universal Electrocatalytic Hydrogen Evolution.

MoS2 exhibits good prospects in electrocatalytic hydrogen evolution. Whereas, the electrocatalytic property of MoS2 is restrained by its insufficient active sites, low electrical conductivity, and slow water dissociation processes. Herein, an aerogel composed of silicon carbide (SiC) and graphene (SiCnw-RGO) was constructed by growing SiC nanowires (SiCnw) in the graphene aerogel (RGO) via the CVD method, and then Ni-Mo-S nanosheets were hydrothermally synthesized on the SiCnw-RGO composite aerogel to develop an efficient pH-universal electrocatalyst. Ni-Mo-S nanosheets supported on SiCnw-RGO (Ni-Mo-S@SiCnw-RGO) exhibit an interesting hierarchical three-dimensional interconnected structure of composite aerogel. The optimal Ni-Mo-S@SiCnw-RGO electrocatalyst exhibits excellent catalytic performance with low Tafel slopes of 60 mV/dec under acidic conditions and 90 mV/dec under alkaline conditions. Density functional theory calculations demonstrate a composite catalyst exhibits advantageous hydrogen adsorption free energy and water dissociation energy barrier. This study provides a reference to design an efficient hierarchical aerogel electrocatalyst.

Enhanced degradation of extracellular polymeric substances by yeast in activated sludge to achieve sludge reduction.

Candida Tropicalis was used to improve the dewaterability of activated sludge (AS) and reduce its biomass by degrading EPS in AS. The protein, polysaccharide, and hydrophilic amino acids in EPS decreased by 54.50, 29.20, and 61.01%, respectively. Meanwhile, molecular weight distribution indicated that yeast degraded macromolecular organics into small molecular ones. The direct addition of yeast to AS was more conducive to EPS degradation. With the addition of 0.75 g/L of wet yeast cells and 24 h of aeration enhanced the dewaterability of AS. The CST and MLSS decreased by 24.44 and 10.51%, respectively. After 30 days of operation of lab-scale continuous SBRs, the CST and MLSS of AS were reduced by 6.37 ± 2.01 and 3.57 ± 0.52%, respectively. FTIR spectroscopy results showed that some hydrophilic functional groups were reduced. This study provides a new approach for the in-situ reduction of AS in wastewater treatment plant.

MOF derived cobalt-nickel bimetallic phosphide (CoNiP) modified separator to enhance the polysulfide adsorption-catalysis for superior lithium-sulfur batteries.

Lithium-sulfur batteries (LSBs) have aroused great research interest due to their high theoretical capacity and high energy density. To further develop lithium-sulfur batteries, it has become more and more important to put more efforts in promoting the adsorption and rapid catalytic conversion of lithium polysulfides (LiPSs). Herein, Ni/Co bimetallic phosphides were encapsulated into nitrogen-doped dual carbon conductive network (NiCoP@NC) by annealing and phosphorizing Ni-ZIF-67 precursor at high temperature. Due to their numerous co-adsorption/catalytic sites and high conductivity of carbon skeleton, the encapsulated Ni/Co phosphides particles could significantly enhance the anchoring and catalytic conversion of LiPSs and provide ultrafast channels for Li+ transport. When used as a modified separator for LSBs, the cells displayed superior performance with an initial capacity of 1083.4 m Ah g-1 at 0.5 C and outstanding cycle stability with a capacity decay rate of only 0.09% per cycle for 300 cycles. Besides, even at high sulfur loading (3.2 mg cm-2), they still present satisfactory performance. Therefore, this study presents a novel strategy on how to use MOF derived bimetallic phosphides with chemical adsorption and catalytic conversion of polysulfides for high-power advanced lithium-sulfur batteries.

PMP-Net++: Point Cloud Completion by Transformer-Enhanced Multi-Step Point Moving Paths.

Point cloud completion concerns to predict missing part for incomplete 3D shapes. A common strategy is to generate complete shape according to incomplete input. However, unordered nature of point clouds will degrade generation of high-quality 3D shapes, as detailed topology and structure of unordered points are hard to be captured during the generative process using an extracted latent code. We address this problem by formulating completion as point cloud deformation process. Specifically, we design a novel neural network, named PMP-Net++, to mimic behavior of an earth mover. It moves each point of incomplete input to obtain a complete point cloud, where total distance of point moving paths (PMPs) should be the shortest. Therefore, PMP-Net++ predicts unique PMP for each point according to constraint of point moving distances. The network learns a strict and unique correspondence on point-level, and thus improves quality of predicted complete shape. Moreover, since moving points heavily relies on per-point features learned by network, we further introduce a transformer-enhanced representation learning network, which significantly improves completion performance of PMP-Net++. We conduct comprehensive experiments in shape completion, and further explore application on point cloud up-sampling, which demonstrate non-trivial improvement of PMP-Net++ over state-of-the-art point cloud completion/up-sampling methods.

Snowflake Point Deconvolution for Point Cloud Completion and Generation With Skip-Transformer.

Most existing point cloud completion methods suffer from the discrete nature of point clouds and the unstructured prediction of points in local regions, which makes it difficult to reveal fine local geometric details. To resolve this issue, we propose SnowflakeNet with snowflake point deconvolution (SPD) to generate complete point clouds. SPD models the generation of point clouds as the snowflake-like growth of points, where child points are generated progressively by splitting their parent points after each SPD. Our insight into the detailed geometry is to introduce a skip-transformer in the SPD to learn the point splitting patterns that can best fit the local regions. The skip-transformer leverages attention mechanism to summarize the splitting patterns used in the previous SPD layer to produce the splitting in the current layer. The locally compact and structured point clouds generated by SPD precisely reveal the structural characteristics of the 3D shape in local patches, which enables us to predict highly detailed geometries. Moreover, since SPD is a general operation that is not limited to completion, we explore its applications in other generative tasks, including point cloud auto-encoding, generation, single image reconstruction, and upsampling. Our experimental results outperform state-of-the-art methods under widely used benchmarks.

A novel rumor detection with multi-objective loss functions in online social networks.

COVID-19 quickly swept across the world, causing the consequent infodemic represented by the rumors that have brought immeasurable losses to the world. It is imminent to achieve rumor detection as quickly and accurately as possible. However, the existing methods either focus on the accuracy of rumor detection or set a fixed threshold to attain early detection that unfortunately cannot adapt to various rumors. In this paper, we focus on textual rumors in online social networks and propose a novel rumor detection method. We treat the detection time, accuracy and stability as the three training objectives, and continuously adjust and optimize this objective instead of using a fixed value during the entire training process, thereby enhancing its adaptability and universality. To improve the efficiency, we design a sliding interval to intercept the required data rather than using the entire sequence data. To solve the problem of hyperparameter selection brought by integration of multiple optimization objectives, a convex optimization method is utilized to avoid the huge computational cost of enumerations. Extensive experimental results demonstrate the effectiveness of the proposed method. Compared with state-of-art counterparts in three different datasets, the recognition accuracy is increased by an average of 7%, and the stability is improved by an average of 50%.

Evaluating the value of p70s6k and mTOR signaling pathway in monitoring exercise-induced central fatigue in rats.

Exercise leads to muscle fatigue and decreased muscle strength in response to contraction activity, and besides, it causes central fatigue. In the current study, we evaluated the value of p70s6k and mTOR signaling pathways in monitoring exercise-induced central fatigue in rats. For this purpose, 12 male rats were divided into control (n=6) and intervention (n=6) groups. The intervention group performed five sessions of climbing a one-meter ladder with a weight hanging on the tail for eight weeks. The weekly load increase was based on the mice's body weight, so it reached 30% in the first week to 200% in the eighth week. In order to evaluate central fatigue, the sedation score system was used. Forty-eight hours after the last training session, a blood sample was prepared, the expression level of related proteins was measured by the ELISA method, and the one-way ANOVA method was used for statistical analysis. This study showed that central fatigue did not significantly affect the total mTOR protein content (F=0.720, P=0.421). However, the level of phosphorylated mTOR in the intervention group had a significant difference compared to the control group (F=684.893, P=0.001, Eta2=0.988). There was a significant effect for total p70S6K content (F=5.84, P=0.04, Eta2=0.42). Also, for phosphorylated p70S6K, there was a significant difference between the mentioned groups (F=7.262, P=0.027, Eta2=0.476). In General, it was shown in this study that central fatigue is directly related to the increase in p70S6K production and phosphorylation of p70S6K and mTOR. Therefore, these two proteins can probably be evaluated for monitoring exercise-induced central fatigue, although we need more evaluations.

Stretchable and Compressible Si3 N4 Nanofiber Sponge with Aligned Microstructure for Highly Efficient Particulate Matter Filtration under High-Velocity Airflow.

Particulate matter (PM) is one of the most severe air pollutants and poses a threat to human health. Air filters with high filtration efficiency applied to the source of PM are an effective way to reduce pollution. However, many of the present filtration materials usually fail because of their high pressure drop under high-velocity airflow and poor thermal stability at high temperatures. Herein, a highly porous Si3 N4 nanofiber sponge (Si3 N4 NFS) assembled by aligned and well-interconnected Si3 N4 nanofibers is designed and fabricated via chemical vapor deposition (CVD). The resulting ultralight Si3 N4 NFS (2.69 mg cm-3 ) processes temperature-invariant reversible strechability (10% strain) and compressibility (50% strain), which enables its mechanical robustness under high-velocity airflow. The highly porous and aligned microstructure result in a Si3 N4 NFS with high filtration efficiency for PM2.5 (99.97%) and simultaneous low pressure drop (340 Pa, only <0.33% of atmospheric pressure) even under a high gas flow velocity (8.72 m s-1 ) at a high temperature (1000 °C). Furthermore, the Si3 N4 NFS air filter exhibits good long-term service ability and recyclability. Such Si3 N4 NFS with aligned microstructures for highly efficient gas filters provides new perspectives for the design and preparation of high-performance filtration materials.

Prevalence and causes of visual impairment in population more than 50 years old: The Shaanxi Eye Study.

To assess the prevalence and causes of visual impairment (VI) in the elderly Chinese rural population in Shaanxi Province.A population-based, cross-sectional study design was used to determine the extent of VI in Chinese people over the age of 50 years in Shaanxi Province. Visual acuity and best-corrected visual acuity were measured using the logarithm of minimum angle of resolution chart. Blindness and low vision were defined according to WHO criteria. The major cause of VI was identified for all participants who were visually impaired.A total of 1912 residents completed a standard questionnaire and underwent a detailed eye examination, and the response rate was 90%. The overall prevalence of blindness and low vision were 1.5% and 8.2%. There was no statistically significant differences between genders in the prevalence of blindness and low vision (P > .05). The prevalence of blindness and low vision was higher among older individuals (P < .05) and lower (P < .05) among those with the highest education level. Cataract, corneal opacity, and glaucoma were considered as the main causes of blindness, which accounted for 67.9%, 10.7%, and 7.1%, respectively. Cataract, refractive error, and age-related macular degeneration were always considered as the leading causes of low vision, which accounted for 66%, 14.7%, and 5.8%, respectively.Cataract, corneal opacity, and glaucoma were the main causes of blindness and low vision in the population aged 50 years or more. The prevalence of these diseases that causes blindness and low vision was higher than that reported in other studies.

Advancing Image Understanding in Poor Visibility Environments: A Collective Benchmark Study.

Existing enhancement methods are empirically expected to help the high-level end computer vision task: however, that is observed to not always be the case in practice. We focus on object or face detection in poor visibility enhancements caused by bad weathers (haze, rain) and low light conditions. To provide a more thorough examination and fair comparison, we introduce three benchmark sets collected in real-world hazy, rainy, and low-light conditions, respectively, with annotated objects/faces. We launched the UG2+ challenge Track 2 competition in IEEE CVPR 2019, aiming to evoke a comprehensive discussion and exploration about whether and how low-level vision techniques can benefit the high-level automatic visual recognition in various scenarios. To our best knowledge, this is the first and currently largest effort of its kind. Baseline results by cascading existing enhancement and detection models are reported, indicating the highly challenging nature of our new data as well as the large room for further technical innovations. Thanks to a large participation from the research community, we are able to analyze representative team solutions, striving to better identify the strengths and limitations of existing mindsets as well as the future directions.

Emerging One-/Two-Dimensional Heteronanostructure Integrating SiC Nanowires with MoS2 Nanosheets for Efficient Electrocatalytic Hydrogen Evolution.

MoS2 has emerged as a good application prospect in the electrocatalytic hydrogen evolution reaction (HER). Nevertheless, the catalytic activity of MoS2 is greatly restricted by its inferior electrical conductivity, inadequate exposure of active edge sites, and sluggish water dissociation dynamics. Herein, a 1D/2D heteronanostructure composed of SiC nanowires wrapped with MoS2 nanosheets was prepared via the hydrothermal synthesis of MoS2 on highly connected SiC nanowires (SiCnw). The nanocomposites exhibit an emerging tectorum-like morphology with interface connections of C-Mo bonds, which benefit the efficient interfacial transmission of electrons. Due to the synergetic catalytic effects of MoS2 nanosheets and SiC nanowires, the MoS2/SiCnw nanocomposites possess efficient catalytic performance with a low Tafel slope (55 mV/dec). SiC nanocrystals could reduce the activated water dissociation energy barrier, and the morphologies of connected nanowires could improve the active site exposure and charge transport. The nanocomposites possess favorable hydrogen adsorption free energy from density functional theory (DFT) calculations. The electrocatalytic performance of MoS2/SiCnw nanocomposites could be further improved by assembling the nanocomposites on a carbon fiber paper to enhance the electronic transmission efficiency.

Construction and Identification of Recombinant HEK293T Cell Lines Expressing Non-structural Protein 1 of Zika Virus.

Background: Zika virus (ZIKV) infection has become a major public health problem all around the world. Early diagnosis of Zika infection is important for better management of the disease. Non-structural protein 1 (NS1) is a potential biomarker for ZIKV infections. The purpose of this study was to produce the ZIKV NS1 protein for establishing serological diagnostic methods for ZIKV. Methods: The cDNA fragment encoding a chimeric protein composed of murine Igκ signal peptide, NS1 and histidine tag was synthesized and cloned into the lentiviral expression vector pLV-eGFP. The resulting expression vector pLV-eGFP-ZIKV-NS1 was packaged and transduced into human embryonic kidney (HEK) 293T cells and clonal cell lines with NS1 gene were generated from the tranduced cells by limiting dilution. Over expressed recombination NS1 (rNS1) fusion protein was purified by nickel affinity chromatography. Mice immunization and enzyme-linked immunosorbent assay (ELISA) were carried out to evaluate the immunogenicity of rNS1. Results: Western blot analysis revealed that the reconstituted cells stably expressed and secreted high levels of approximately 45-kDa NS1, and no significant changes were observed in green fluorescent protein (GFP) fluorescence ratio and fluorescence intensity. The scanned gels showed that the purity of the purified rNS1 was 99.42%. BALB/c mice were then immunized with purified rNS1 and a high level of antibodies against NS1 was elicited in the mice. Conclusion: Overall, recombinant NS1 proteins were successfully purified and their antigenicity was assessed. Immunization of mice with recombinant proteins demonstrated the immunogenicity of the NS1 protein. Thus, the generated recombinant NS1 can be potentially used in the development of serological diagnostic methods for ZIKV.

Angiotensin II type 2 receptor promotes apoptosis and inhibits angiogenesis in bladder cancer.

BACKGROUND: Bladder cancer (BCa) is the ninth most common form of cancer in the world. There is a continuing need not only for improving the accuracy of diagnostic markers but also for the development of new treatment strategies. Recent studies have shown that the renin-angiotensin system (RAS), which include the angiotensin type 1 (AT1R), type 2(AT2R), and Mas receptors, play an important role in tumorigenesis and may guide us in meeting those needs. RESULTS: In this study, we first observed that AT1R and Mas expression levels were significantly upregulated in BCa specimens while AT2R was significantly downregulated. Viral vector mediated overexpression of AT2R induced apoptosis and dramatically suppressed BCa cell proliferation in vitro, suggesting a therapeutic effect. Investigation into the mechanism revealed that the overexpression of AT2R increases the expression levels of caspase-3, caspase-8, and p38 and decreases the expression level of pErk. AT2R overexpression also leads to upregulation of 2 apoptosis-related genes (BCL2A1, TNFSF25) and downregulation of 8 apoptosis-related genes (CASP 6, CASP 9, DFFA, IGF1R, PYCARD, TNF, TNFRSF21, TNFSF10, NAIP) in transduced EJ cells as determined by PCR Array analysis. In vivo, we observed that AT2R overexpression caused significant reduction in xenograft tumors sizes by downregulation VEGF and induction of apoptosis. CONCLUSIONS: Taken together, the data suggest that AT1R, AT2R or Mas could be used as a diagnostic marker of BCa and AT2R is a promising novel target gene for BCa gene therapy.

[The establishment of 5637 bladder cancer cell line with stable overexpression of miR-449c].

Objective To establish a human bladder cancer cell line that stably overexpresses miR-449c. Methods The DNA fragments encoding pre-miR-449c were amplified from genomic DNA templates of HEK293 cells using high-fidelity PCR and cloned into FtetUGW-T vector. The recombinant plasmid was verified by sequencing and applied for lentivirus packaging. Human bladder cancer 5637 cells were infected with the lentivirus and the infected cells after selection with puromycin were observed using an inverted fluorescent microscope for enhanced green fluorescent protein (EGFP) expression, real-time quantitative PCR for miR-449c expression and Western blotting for the expression of its downstream target C-myc. Results The FtetUGW-T/miR-449C lentivirus was successfully established. The human 5637 bladder cancer cells infected with the lentivirus expressed EGFP and overexpressed miR-449c. The expression of c-myc in the cells that stably overexpressed miR-449c was significantly reduced compared with control cells. Conclusion 5637 bladder cancer cell line that stably overexpresses miR-449c is successfully established.

Enrichment and purification of total flavonoids from Flos Populi extracts with macroporous resins and evaluation of antioxidant activities in vitro.

Enrichment and purification of total flavonoids from Flos Populi extracts were studied using five macroporous resins. The static tests indicated that NKA-9 resin was appropriate and its adsorption data were well fitted to the Langmuir and Freundlich isotherms. To optimize the separation process, dynamic adsorption and desorption tests were carried out. The optimal adsorption parameters were initial concentrations in sample solution of 7.64mg/mL, pH of 5.0, sample loading amount of 2.3BV, flow rate of 2BV/h, temperature of 25°C. The optimal desorption parameters were deionized water and 20% ethanol each 5BV, then 60% ethanol of 10 BV, flow rate of 2BV/h. After one run treatment with NKA-9 resin, the content of total flavonoids in the product increased from 11.38% to 53.41%, and the recovery yield was 82.24%. The results showed that NKA-9 resin revealed a good ability to enrichment total flavonoids from Flos Populi, and the method can be referenced for the enrichment of total flavonoids from other materials. The antioxidant activities of the purified flavonoids were further evaluated in vitro. It showed that the DPPH radical scavenging increased from 59.46% to 82.63% at different concentrations (0.06-0.14mg/mL). At different concentrations (0.6-1.4mg/mL), the hydroxyl radical scavenging increased from 35.39% to 74.12%. Moreover, the reducing ability and total oxidant capacity appeared to be dose-dependent of flavonoids. It indicated that the purified flavonoids can be used as a source of potential antioxidant.