The rheological properties of shear thickening fluid reinforced with SiC nanowires

The rheological properties of shear thickening fluid (STF) reinforced with SiC nanowires were investigated in this paper. Pure STF consists of 56 vol% silica nano-particles and polyethylene glycol 400 (PEG 400) solvent was fabricated; and a specific amount of SiC nanowires were dispersed into this pure STF, and then the volume fraction of PEG400 was adjusted to maintain the volume fraction of solid phase in the STF at a constant of 56%. The results showed there was almost 30% increase in the initial and shear thickening viscosity of the STF reinforced with SiC nanowires compared to the pure STF. Combining with the hydrodynamic cluster theory, the effect of the mechanism of SiC nanowire on the viscosity of STF was discussed, and based on the experimental results, an analytical model of viscosity was used to describe the rheological properties of STF, which agreed with the experimental results

The effect of graphene on the yarn pull-out force and ballistic performance of Kevlar fabrics impregnated with shear thickening fluids

The ballistic performance of Kevlar fabric impregnated with different shear thickening fluids (STFs) were investigated at various impact velocities. The SiO2 nanoparticle based STFs were reinforced with graphene and showed a significant increase in viscosity and shear thickening efficiency compared to pure STF. Ballistic experiments were performed on fabric treated by different STFs, and different failure modes including yarn slipping, extraction, and breakage in shear failure were obtained. To better understand how different STFs affect ballistic performance, single yarn pull-out tests were also carried out to examine the shear strength and friction between the interlocking yarns of fabric treated with STF. The results showed that STF reinforced with graphene is better at preventing the yarns from slipping, and the single yarn pull-out force is almost 5 times more than pure STF. Moreover, reinforced STF also has a significant influence on the ballistic limit and energy absorption of Kevlar fabrics. And the increased amplitude of energy absorption is almost 20% more than the pure STF/Kevlar load case. Combining with the energy absorption and different failure modes, the effect of STF on the failure mechanism of neat/treated fabric was also discussed

Dynamic response of shear thickening fluid reinforced with SiC nanowires under high strain rates

In this letter, SiC nanowires were adopted to reinforce the nanoparticle-based shear thickening fluid (STF) to improve its rheological properties. The reinforced STF showed a significant increase in viscosity. A Split-Hopkinson pressure bar was implemented to evaluate the dynamic response of STF at strain rates in the range of 3 × 103–1.2 × 104/s. For the pure STF, the flow stress reaches a saturation value with increasing strain rates and shows almost no strain rate sensitivity, whereas the flow stress of the reinforced STF increases with strain rates, and the strain rate sensitivity to flow stress is obvious owing to the resistance of nanowires. The essence of this study is to reveal that there is a limiting value of the flow stress of traditional nanoparticle-based STF at high strain rates due to the lubrication force among particles. SiC nanowires can be used to break this limitation of the nanoparticle-based STF

Dynamic Response and Deformative Mechanism of the Shape Memory Polymer Filled with Low-Melting-Point Alloy under Different Dynamic Loads

Low-melting-point alloy (LMPA) was used as an additive to prepare epoxy-resin-based shape memory polymer composites (LMPA/EP SMP), and dynamic mechanical analyzer (DMA) tests were performed to demonstrate the shape memory effect, storage modulus, and stiffness of the composites under different load cases. The composites exhibited an excellent shape recovery ratio and shape fixity ratio, and a typical turning point was observed in the storage modulus curves, which was attributed to the melting of the LMPA. In order to investigate the dynamic deformation mechanism at high strain rates, split Hopkinson pressure bar (SHPB) experiments were performed to study the influence of the strain rate and plastic work on the dynamic mechanical response of LMPA/EP composites. The results showed that there was a saturated tendency for the flow stress with increasing strain rate, and the composites exhibited a typical brittle failure mode at high strain rate. Moreover, an obvious melting phenomenon of the LMPA was observed by SEM tests, which was due to the heat generated by the plastic work at high strain rate. The fundamental of the paper provided an effective approach to modulate the stiffness and evaluate the characteristics of SMP composites

Phononic crystal lens with an asymmetric scatterer

A novel 2D gradient index phononic crystal (GRIN PC) lens was designed by rotating scatterers that theoretically differs from the traditional GRIN PC lens by altering fill fraction, lattice constant or material parameters. Three-petal epoxy cylinders were designed as scatterers and embedded into a homogenous steel matrix. Rotation of the three-petal cylinder results in an asymmetry about x axis, and there is a change in the first dispersion band which is related to group velocity and the refractive index. The equivalent refraction index along the y direction was modulated to satisfy the distribution of a hyperbolic secant profile using a specific rotation angle of the scatterer. The focus of the acoustic wave in the PC lens with a rotating three-petal scatterer was investigated using a numerical method, and the results showed that the focus length agreed with the trajectories derived from the analytical solution. Results also showed that the range of the operation reduced frequency is 0.18. The influence of the operation frequency on the focusing efficiency and focal length was also discussed. The work provides a convenient method for fabricating a phononic crystal lens and makes the lens suitable for relevant applications

The rheological properties of shear thickening fluid reinforced with SiC nanowires

The rheological properties of shear thickening fluid (STF) reinforced with SiC nanowires were investigated in this paper. Pure STF consists of 56 vol% silica nano-particles and polyethylene glycol 400 (PEG 400) solvent was fabricated; and a specific amount of SiC nanowires were dispersed into this pure STF, and then the volume fraction of PEG400 was adjusted to maintain the volume fraction of solid phase in the STF at a constant of 56%. The results showed there was almost 30% increase in the initial and shear thickening viscosity of the STF reinforced with SiC nanowires compared to the pure STF. Combining with the hydrodynamic cluster theory, the effect of the mechanism of SiC nanowire on the viscosity of STF was discussed, and based on the experimental results, an analytical model of viscosity was used to describe the rheological properties of STF, which agreed with the experimental results. Keywords: Shear thickening fluid (STF), Nanowire, Rheology, Viscosity, Analytical mode

Table_1_mbtD and celA1 association with ethambutol resistance in Mycobacterium tuberculosis: A multiomics analysis.xlsx

Ethambutol (EMB) is a first-line antituberculosis drug currently being used clinically to treat tuberculosis. Mutations in the embCAB operon are responsible for EMB resistance. However, the discrepancies between genotypic and phenotypic EMB resistance have attracted much attention. We induced EMB resistance in Mycobacterium tuberculosis in vitro and used an integrated genome–methylome–transcriptome–proteome approach to study the microevolutionary mechanism of EMB resistance. We identified 509 aberrantly methylated genes (313 hypermethylated genes and 196 hypomethylated genes). Moreover, some hypermethylated and hypomethylated genes were identified using RNA-seq profiling. Correlation analysis revealed that the differential methylation of genes was negatively correlated with transcription levels in EMB-resistant strains. Additionally, two hypermethylated candidate genes (mbtD and celA1) were screened by iTRAQ-based quantitative proteomics analysis, verified by qPCR, and corresponded with DNA methylation differences. This is the first report that identifies EMB resistance-related genes in laboratory-induced mono-EMB-resistant M. tuberculosis using multi-omics profiling. Understanding the epigenetic features associated with EMB resistance may provide new insights into the underlying molecular mechanisms.</p