Search

• Pine sawdust was fractionated in an ethanol-water mixed solvent (1:1, v/v). • Effects of various catalysts on lignin products were studied at 180 °C for 60 min. • 59 % crude lignin was obtained with 15 % H2SO4 catalysis. • Crude lignin obtained with 15 % formic acid catalysis had a purity of 55 %. • Crude lignin obtained under 15 % NaOH catalysis had a purity of 22 %. A cost-effective process has been developed for fractionating pine sawdust into lignin and cellulose fractions in an ethanol-water mixed solvent. The effects of temperature, different types of catalysts (i.e., strong acid, weak acid and alkali), and residence time, with respect to yields and purity of the crude lignin (degraded products) and crude cellulose (solid residue) were investigated. It is found that the purity of crude lignin was higher but with a lower product yield under a weak acid or alkali catalysis in comparison to strong acid treatments. According to the analysis results, the optimal conditions for fractionation process were as follows: a mixed solvent of ethanol-water (1:1, v/v), 15 % formic acid (based on dry biomass), 180 °C, and 60 min. The yield of the resulted crude lignin was 29.2 % with a purity of 54.6 %, and yield of crude cellulose was 64.6 % with a high purity of 84.3 %. [ABSTRACT FROM AUTHOR]

Fabric-based electromagnetic wave (EMW) absorption materials are desirable owing to their inherent flexibility, cost-effectiveness, and easily conformable lightweight structures. However, the problems such as high density and susceptibility to abrasion limit their applications and service life. Herein, flexible fabric-based EMW absorption material (FEMWAM) were prepared by a multiscale synergistic approach. At the microscopic scale, CF@NiCo 2 O 4 @MnO 2 absorbents with enhanced impedance matching and interfacial polarization are prepared by solvent method and hydrothermal process. The influence of heterostructure on the electromagnetic response is also examined. At the macroscopic scale, flexible FEMWAM are prepared by freeze-drying. The electromagnetic parameters of FEMWAM was effectively regulated by altering the amount of the CF@NiCo 2 O 4 @MnO 2 absorbents, which achieve excellent EMW absorption performance and thermal insulation property while maintaining flexibility. The minimal reflection loss (RL min) of −27.8 dB can be achieved at a thickness of 2.70 mm, and an EAB covering the complete X-band can be obtained when the thickness is in the range of 3.20–3.26 mm. The large thickness range provides convenience for the control of dimensional accuracy in actual production, so as to better adapt to practical applications. These findings provide effective guidance for the preparation of EMW absorption materials with excellent flexibility, thermal insulation properties and absorption performance. [Display omitted] [ABSTRACT FROM AUTHOR]

In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLSs) play an essential role in cartilage destruction. Aggressive migration and invasion by FLSs significantly affect RA pathology. Kaempferol has been shown to inhibit cancer cell migration and invasion. However, the effects of kaempferol on RA FLSs have not been investigated. Our study aimed to determine the effects of kaempferol on RA both in vitro and in vivo. In vitro, cell migration and invasion were measured using scratch assays and the Boyden chamber method, respectively. The cytoskeletal reorganization of RA FLSs was evaluated by immunofluorescence staining. Matrix metalloproteinase (MMP) levels were measured by real-time PCR, and protein expression levels were measured by western blotting. In vivo, the effects of kaempferol were evaluated in mice with CIA. The results showed that kaempferol reduced migration, invasion and MMP expression in RA FLSs. In addition, we demonstrated that kaempferol inhibited reorganization of the actin cytoskeleton during cell migration. Moreover, kaempferol dramatically suppressed tumor necrosis factor (TNF)-α-induced MAPK activation without affecting the expression of TNF-α receptors. We also demonstrated that kaempferol attenuated the severity of arthritis in mice with CIA. Taken together, these results suggested that kaempferol inhibits the migration and invasion of FLSs in RA by blocking MAPK pathway activation without affecting the expression of TNF-α receptors. [ABSTRACT FROM AUTHOR]

Accurately detect vehicles or pedestrians from 3D point clouds (3D object detection) is a fast developing research topic in autonomous driving and other domains. The fundamental component for feature extraction in 3D object detection is Set Abstraction (SA), which can downsample points while aggregating points to extract features. However, the current SA ignores the geometric and semantic properties of point clouds and may miss to detect remote small objects. In this paper, FocusSA is proposed, which consists two modules for enhancing useful feature extraction in the SA layer to improve 3D object detection accuracy. At first, Focused FPS (FocFPS) is proposed to evaluate the foreground and boundary scores of the points and reweighs the Furthest Point Sampling (FPS) using the evaluated scores to retain more contextual points in downsampling. Then a Geometry-aware Feature Extraction (GeoFE) module is proposed to add geometric information to enrich the awareness of geometric structure in feature aggregation. To evaluate the performances of the proposed methods, we conduct extensive experiments on three difficulty levels of Car class in KITTI dataset. The experimental results show that on "moderate" instances, our results outperform the state-of-the-art method by 1.08%. Moreover, FocusSA is easy to be plugged in popular architectures. [ABSTRACT FROM AUTHOR]

[Display omitted] • CF@MnO 2 composites with controllable structure were prepared by a facile hydrothermal method. • The growth process of MnO 2 was studied. • The effect of micro morphology on electromagnetic wave absorption performance was studied. Recently, electromagnetic wave (EMW) absorption materials with enhanced and tunable EMW absorption performance are required in practical applications, and attaining such performance by a simple method remains a vital challenge. In this study, manganese dioxide (MnO 2) with controllable structures were vertically grown on carbon fibers (CF) through a hydrothermal method. The sheet-like (CF@MnO 2 -NS) and wire-like (CF@MnO 2 -NW) structures were obtained by merely adjusting the solution chemistries ([K+] and [H+]) and reaction time. The wire-like structure exhibited high attenuation capability due to a larger specific surface area and dielectric resonance, but exhibited a relatively poor impedance matching ratio resulting in inferior EMW absorption performance at low frequencies. However, the sheet-like structure exhibited better EMW absorption performance overall. The minimum reflection loss (RL min) value of CF@MnO 2 -NS and CF@MnO 2 -NW reached −56.6 dB and −52.9 dB, respectively. Additionally, the EMW absorption performance varies with frequency. CF@MnO 2 -NW performed better in the X-band, while CF@MnO 2 -NS achieved an excellent performance in the C-band. This study provides a simple approach for designing EMW absorption materials with controllable morphologies and for realizing tunable EMW performances. [ABSTRACT FROM AUTHOR]

Abstract: Al–TiO2–Fe–Fe2O3–MnO2, as the main reaction system, was selected to prepare the agglomerate powders containing energy (APCE) on 50–90μm by balling, drying, carbonating, grinding and sieving. Self-reactive quenching technology, which is integrated with flame spraying, self-propagating high-temperature synthesis (SHS) and rapid solidification, was used to spray and melt the APCE. Flight combustion of the APCE was analyzed by high-speed photography, water quenching, collisions and Gibbs free energy graph, and surface morphologies of quenching products were characterized by SEM. The results show that the APCE goes through three stages, which mean heat storage (0–80mm, 66–72ms), heat releasing (80–240mm, 73–83ms) and after combustion (240–400mm, 84–99ms), to form hollow ceramic droplets which decisively affect the quality of hollow multiphase ceramic microspheres. Collisions and burst may be the main reasons to produce flame retrogression and affect the particle size distribution of hollow multiphase ceramic microspheres simultaneously. [Copyright &y& Elsevier]

Wurtzite-type Zn 0.96 Co 0.04 O nanotubes are prepared through coaxial electrospinning technology and heat-treatment for 2 h at 600, 700 and 800 °C. The phases, morphology, microwave absorption properties and infrared emissivity are investigated by TGA, XRD, SEM, TEM, vector network analyzer and a IR-2 infrared emissivity tester respectively. The results show that pure wurtzite-type Zn 0.96 Co 0.04 O is formed at 600 °C and above. As the heat-treatment temperature increas, Zn 0.96 Co 0.04 O exhibit the morphology of hollow tubes, short nanotubes and irregular nanoparticles. Dielectric loss is the main loss mechanism of Zn 0.96 Co 0.04 O nanotubes. The matching thickness of Zn 0.96 Co 0.04 O nanotubes is 2 mm, at which the microwave absorption properties are fine. The minimum reflectivity is −20.3 dB at 9.5 GHz, and the effective absorption frequency band less than −10 dB is 8.4–12.0 GHz, with the bandwidth of 3.6 GHz. The average infrared emissivity value of Zn 0.96 Co 0.04 O nanotubes is 0.72. • In this work, wurtzite-type Zn 0.96 Co 0.04 O nanotubes are prepared through coaxial electrospinning technology and heat-treatment. The effects of heat-treatment on morphology and hollow morphology on the microwave absorbing properties and infrared emissivity are mainly investigated. • As the temperature increas, Zn 0.96 Co 0.04 O exhibit the morphology of hollow tubes, short nanotubes and irregular nanoparticles. • Dielectric loss is the main loss mechanism of Zn 0.96 Co 0.04 O nanotubes. The matching thickness of Zn 0.96 Co 0.04 O nanotubes is 2 mm, at which the microwave absorption properties are fine. The minimum reflectivity is −20.3 dB at 9.5 GHz, and the effective absorption frequency band less than −10 dB is 8.4–12.0 GHz. • The average infrared emissivity value of Zn 0.96 Co 0.04 O nanotubes is 0.72. Nanotubes has can reduce the transfer and absorption of infrared radiation energy. [ABSTRACT FROM AUTHOR]