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  • Author: Fei Yan x
  • Industrial Chemistry x
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Abstract

Fibre fabrics in liquid composite moulding can be considered as dual-scale porous media. In different gap scales, an unsaturated flow is produced during the mould filling process. This particular flow behaviour deviates from the traditional Darcy’s law, which is used to calculate the filling pressure and will cause errors. To prove the mechanism of this unsaturated flow, an experimental device was set up with a one-dimensional constant flow rate. The influencing factors, such as injected media, flow velocity and fibre fabric, were investigated in this study. Based on the experimental data, several useful conclusions were drawn, providing good references for optimising the process parameters and controlling the product quality.

Abstract

In this work, we have designed and synthesized the fluorescent probe 1, which was capable to selectively detect fluoride anion (F). More importantly, the probe 1 possessed near-infrared excitation and emission wavelengths (excitation at 650 nm and emission at 695), and the probe solution had changed dramatically from yellow to cyan with the addition of F. In addition, the fluorescence intensity exhibited perfectly positive correlation with concentration of F concentration from 0 to 40 μM (R2 = 0.9972), which offered the important condition for quantitative analysis. The probe 1 owned detection limit of 46 nM. Therefore, this near-infrared probe can be of great benefit for detecting F in practical application.

Abstract

BCN coatings with different chemical compositions were prepared using RF magnetron sputtering via adjusting N2 flow. The influence of N2 flow on the bonding structure, mechanical and tribological properties of coating was studied. The structural analysis indicated the coexistence of B-N, B-C, and N-C bonds, suggesting the formation of a ternary BCN hybridization. The maximum Vickers hardness of 1614.7 HV was obtained at the low N2 flow (5 sccm), whereas the adhesion strength of BCN coatings on 316L stainless steel was improved with an increase of N2 flow. The friction behavior of BCN coatings sliding against different materials (acerbic, beech and lauan wood) was performed using ball-on-disk tribo-meter in air. The low friction coefficient was easier to obtain as sliding against hardwood i.e. acerbic balls. BCN-5 and BCN-10 coatings presented better wear resistance regardless of softwood or hardwood, whilst other two coatings were more suitable for mating softwood i.e. beech and lauan.

Abstract

A simple and coumarin-based fluorescence probe has been designed and synthesized with silyl group as recognition group of fluoride ions (F−) in this study. The results showed that the fluorescence intensity of the probe displayed prominent enhancement with addition of F− at 445 nm with incubation of 1 min. There was an excellent linear relationship between fluorescence intensity and fluoride concentration from 0 to 30 μM (0~0.57 ppm), which offered the important condition for the quantitative analysis. In addition, the highly selective response to fluorion, the low detection limit with 28 nM (0.532 ppb), low toxicity and bioimaging afforded an advantage for practical application and detecting fluoride in biological systerms.

Abstract

More mechanical information on fibers is needed for better understanding of the complex mechanical behavior of bamboo as well as optimizing design of bamboo fiber based composites. In this paper, in situ imaging nanoindentation and an improved microtensile technique were jointly used to characterize the longitudinal mechanical behavior of fibers of Moso bamboo (Phyllostachys pubescens Mazei ex H. de Lebaie) aged between 0.5 and 4 years. These methods show that 0.5-year-old fibers have similar mechanical performances to their older counterparts. The average longitudinal tensile modulus and tensile strength of Moso bamboo fibers ranges from 32 to 34.6 GPa and 1.43 to 1.69 GPa, respectively, significantly higher than nearly all the published data for wood fibers. This finding could be attributed to the microstructural characteristics of the small microfibrillar angle and scarcity of pits in bamboo fibers. Furthermore, our results directly support the assumption that the widely used Oliver-Pharr analysis method in nanoindentation test significantly underestimates the longitudinal elastic modulus of anisotropic plant cell wall.

Abstract

The in situ imaging nanoindentation technique was used to investigate how the moisture content (MC) affects the longitudinal mechanical properties of Masson pine cell wall. Furthermore, nanoindentation tests in liquid water were performed. The results indicate that elastic modulus, hardness, and compression yield stress of wood wall are all linearly correlated to the selected MC region in the range from 4.5% to 13.1%. Remarkable differences were found between the experimental values measured in water and the extrapolated values based on regression equations below fiber saturation point.

Abstract

Results obtained using a bipolar pulsed DBD reactor for Indigo Carmine (IC) water treatment are reported in this investigation. Effects of such parameters as gas flow rate, solution conductivity, pulse repetitive rate and ect., on color removal efficiency of IC solution were studied. The results showed that color removal efficiency was greatly enhanced by bubbling air into the reactor. Decolorization efficiency of the reactor increased with the increase of the pulse repetitive rate, decreased with the increase of the initial solution conductivity and gap distance. In addition, concentrations of ozone in the effluent gases and hydroxyl peroxide in the aqueous phase were determined and their functions on the decolorization were analyzed.

Abstract

Based on the geometries from molecular dynamics simulations and a package compiled by us, the interactions between graphene nanosheet (GNS) and nine types of flexible polymers have been investigated with force field. Both the van der Waals (vdW) interaction and the electrostatic interaction (EI) for two same polymer chains and between a polymer and a GNS were calculated and compared. The effect of cut-off distance was explored. It was found that the cut-off distance plays a significant role in EI energy, but a less important role in vdW energy when the cut-off distance is over 9.5 Å. The reasonable cut-off distances for EI and vdW interactions for simulation are suggested.

Abstract

Bamboo is one of the world’s fastest growing plants. They reach a final height of 15–40 m during a period of 40–120 days. The full height is reached by intercalary growth of each node. However, it is very difficult to detect the complex vascular system in a bamboo node using traditional methods. X-ray computed microtomography (μCT) is a noninvasive novel approach to the three-dimensional (3D) visualization and quantification of biological structures. In the present article, μCT has been applied to provide insights into the internal structure of bamboo node, where three branches are connected. The picture obtained could hardly be obtained by any other means. The bamboo nodal characteristics of three transverse and axial sections are presented. The complex 3D network of vascular bundles has been directly obtained for the first time.