Use of Shore Hardness Tests for In-Process Properties Estimation/Monitoring of Silicone Rubbers

Casting is an important rubber manufacturing process for both production and material developments. A quick and flexible way of testing the constitutive materials properties of rubber products is very important for optimising the processing parameters and quality control. In many cases, standard tests such as tensile or compression tests are time consuming and require a large volume of materials. This work reports some recent work in using a combined numerical and experimental approach to characterise the properties of rubber materials during a casting process. Durometer shore hardness is used to test silicone rubbers (as a model material) with different compositions on different moulding planes and the linear elastic property is estimated from the hardnesses. The predicted properties are systematically compared with the experimental tests on hard and soft silicone rubber samples with different compositions. The work shows that shore hardness can be used as an effective way to monitor the materials properties during a moulding process for process optimisation and quality control

Movement analysis of lower limb during backward walking with unstable intervention

Backward walking (BW), an emerging rehabilitative and training modality, was integrated with unstable sole construction with various hardness levels to analyze the kinematic and kinetic characteristics of the lower extremities. Eighteen participants volunteered to participate in the test. They performed walking tests under three conditions: 1) BW with normal shoes (NBW); 2) BW with unstable shoes with soft unstable elements (UBW-S); 3) BW with unstable shoes with hard unstable elements (UBW-H). The results show increased hip and ankle flexion and increased knee flexion-extension extent in the stance phase during BW with unstable shoes. The motor control mechanism of unstable BW enhanced the rehabilitation of lower limb deficiency. The attached unstable elements (UBW-S and UBW-H) induced local perturbation to stimulate proprioceptive ability and the neuromuscular system, changing the plantar loading distribution in a certain region. Future study should concentrate on the possible rehabilitative effect of unstable BW on neurological disorders and motor system deficiency

Enhanced Auxetic and Viscoelastic Properties of Filled Reentrant Honeycomb

Honeycombs or foams with reentrant microstructures exhibit effective negative Poisson's ratio. Although they are light weight due to inherently empty space, their overall stiffness and damping are somewhat limited. With judiciously chosen filler material to fill the voids in star-shaped honeycomb, it is numerically demonstrated its auxeticity may be enhanced. By combining the filler and skeleton, the hierarchical composite materials are constructed. The magnitude of the enhancement depends on inner and outer filler's modulus mismatch, as well as the types of filling. Filler's auxeticity also largely enhances overall auxeticity of the outer- and all-filled honeycomb. In addition, for outer-filled honeycomb, its effective viscoelastic modulus and damping are significantly increased, while maintaining relatively light weight, due to local stress concentration. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Ethanolic Extract of Aconiti Brachypodi Radix Attenuates Nociceptive Pain Probably Via Inhibition of Voltage-Dependent Na+ Channel

Aconiti Brachypodi Radix, belonging to the genus of Aconitum (Family Ranunculaceae), are used clinically as anti-rheumatic, anti-inflammatory and anti-nociceptive in traditional medicine of China. However, its mechanism and influence on nociceptive threshold are unknown and need further investigation. The analgesic effects of ethanolic extract of Aconiti Brachypodi Radix (EABR) were thus studied in vivo and in vitro. Three pain models in mice were used to assess the effect of EABR on nociceptive threshold. In vitro study was conducted to clarify the modulation of the extract on the tetrodotoxin-sensitive (TTX-S) sodium currents in rat’s dorsal root ganglion (DRG) neurons using whole-cell patch clamp technique. The results showed that EABR (5-20 mg/kg, i.g.) could produce dose-dependent analgesic effect on hot-plate tests as well as writhing response induced by acetic acid. In addition, administration of 2.5-10 mg/kg EABR (i.g.) caused significant decrease in pain responses in the first and second phases of formalin test without altering the PGE2 production in the hind paw of the mice. Moreover, EABR (10 μg/ml -1 mg/ml) could suppress TTX-S voltage-gated sodium currents in a dose-dependent way, indicating the underlying electrophysiological mechanism of the analgesic effect of the folk plant medicine. Collectively, our results indicated that EABR has analgesic property in three pain models and useful influence on TTX-S sodium currents in DRG neurons, suggesting that the interference with pain messages caused by the modulation of EABR on TTX-S sodium currents in DRG neurones may explain some of its analgesic effect

Preparation and analysis of a new bioorganic metallic material

Biofouling on metal surfaces is one of the main reasons for increased ship drag. Many methods have already been used to reduce or remove it with moderate success. In this study, a synthetic peptide has been utilized to react with 304 stainless steel aiming to generate a bioorganic stainless steel using a facile technique. After the reaction, white matter was found on the surface of the treated stainless steel via SEM, whilst the nontreated stainless steel had none. Elemental analysis confirmed that excessive N existed on the surface of the treated samples using an integrated SEM-EDS instrument, implying the presence of peptides binding on the surface of the bioorganic stainless steel. The FTIR spectra showed amide A and II peaks on the surface of the bioorganic stainless steel suggesting that either the peptides grafted onto the steel surface or the polypeptide composition accumulated on the steel samples. XPS analysis of the treated steel demonstrated that there was nitrogen bonding on the surface and it was a chemical bond via a previously unreported chemical interaction. The treated steel has a markedly increased contact angle (water contact angle of 65.7 ± 4.7° for nontreated steel in comparison to treated, 96.4 ± 2.1°), which supported the observation of the wettability change of the surface, i.e. the decrease of the surface energy value after peptide treatment. The changes of the surface parameters (such as, Sa, Sq, Ssk and Sku) of the treated steel by surface analysis were observed

Porous hydroxyapatite reinforced with collagen protein

Porous hydroxyngatite (HAP) with certain porosity and pore size was prepared, and incorporated with bovine collagen protein. The composition and structure of the HAP was confirmed by X-Rag Diffraction (XHD) and ICP. Scanning Electron Microscopy (SEM), mechanical tests and in vitro degradation were performed. Collagen protein vith low antigenicity was obtained from bovine tendon by enzyme digestion, and was then forced to fill in the HAP matrix to form composites. Scanning Electron Microscopy (SEM), Mechanical tests and in vitro degradation were performed. The test results show that first, HAP thus made has specific pore size and directions; second, mechanical properties of the composites have been markedly improved; third, the in vitro degradation rate of the composite is almost the same as and mainly controlled by the degradation rate of collagen

Microstructure and wear resistance of (Nb,Ti)C carbide reinforced Fe matrix coating with different Ti contents and interfacial properties of (Nb,Ti)C/α-Fe

In this work, the (Nb,Ti)C reinforced Fe matrix coatings were prepared by gas metal arc welding (GMAW) hardfacing technology. The microstructure, hardness and wear resistance of (Nb,Ti)C reinforced coatings with different Ti contents were investigated by experiments. The interfacial properties of (Nb,Ti)C/α-Fe interfaces were calculated by first principles method based on density functional theory (DFT). The experiment results show that as the Ti content in the coating changes from 0.15 to 0.41 wt%, the average diameter of NbC primary carbide grains decreases from 3.2 μm to 1.7 μm and their amount increase from 0.35 to 0.51 μm−2. The coating with 0.15 wt% Ti performs the lowest wear loss, which is 0.47 g/N ∗ cm2. From the calculated results, the interfacial combination between carbide and matrix are improved after Ti addition. The adhesion work of (Nb,Ti)C/Fe interfaces show the following order: CNb-Fe < NbC-Fe < CTiNb-Fe < CNbTi-Fe < NbTiC-Fe < TiNbC-Fe. In CTiNb-Fe, CNbTi-Fe and CNb-Fe surfaces, weak Fe-M covalent bonds are formed at the interfaces. In NbC-Fe, NbTiC-Fe and TiNbC-Fe surfaces, strong Fe–C and M-C covalent bond can be found at (Nb,Ti)C/α-Fe interfaces, besides, Fe–C ionic bonds are also formed

Refinement and homogenization of M7C3 carbide in hypereutectic Fe-Cr-C coating by Y2O3 and TiC

The microstructures of the hypereutectic Fe-Cr-C, Fe-Cr-C-Ti and Fe-Cr-C-Ti-Y2O3 coatings were observed by OM. The phase structures were characterized by XRD and XPS. The elemental distributions were analyzed by EDS. The interface relationship between TiC and nano-Y2O3 were observed by TEM and analyzed by lattice misfit theory. From the metallographic observations, the primary M7C3 carbide can be refined by Ti additive, while it is inhomogeneously distributed. However, the primary M7C3 carbide can also be refined further by adding Ti additive and nano-Y2O3 simultaneously, and it is homogeneously distributed. From the phase constituent analysis, TiC is formed by Ti additive, while TiC and Y2O3 are found by adding Ti additive and nano-Y2O3 simultaneously. From the elemental distribution mappings and TEM images, TiC nucleates upon nano-Y2O3 with orientation relationship {001}Y2O3//{001}TiC in the hypereutectic Fe-Cr-C-Ti-Y2O3 coating. By misfit computation, the lattice misfit between Y2O3 (001) plane and TiC (001) plane is 7.3%, which suggests that Y2O3 can act as the heterogeneous nucleus of TiC so that TiC particles are increased and dispersedly distributed. These numerous dispersed TiC particles can further act as the heterogeneous nucleus of the primary M7C3 carbide, which play a role in refining primary M7C3 carbide and promoting its homogenization

Effect of bainite layer by LSMCIT on wear resistance of medium-carbon bainite steel at different temperatures

In this work, bainite layer was prepared by Laser surface melting combined with isothermal treatment (LSMCIT) at 250ºC. The microstructures of the samples were analyzed by scanning electron microscopy (SEM), X-ray Diffraction (XRD) and transmission electron microscopy (TEM). Their wear resistances at 20ºC, 100ºC and 200ºC were measured using reciprocating tribometer. After the wear test, the confocal laser scanning microscope and SEM were used to characterize the topography of all abrasion surfaces, and the phase transformations occurred on the contact surfaces were analyzed by XRD. The results show that the microstructure of the LSMCIT sample has been refined to nanoscale. The wear volume reduction ratio of LSMCIT sample is 40.9% at 20ºC. The wear resistances of the samples are decreased with increasing of the temperature, however, the decrease in amplitude of the bainite is relatively small. The harder surface of the LSMCIT sample can provides higher mechanical support, and the white-etching layer on surface are difficult to remove by the reciprocating friction. The wear resistances of the LSMCIT samples at 20ºC, 100ºC and 200ºC are excellent, which shows the wide temperature ranges in wear applications

Synthesis and Application of Carbon–Iron Oxide Microspheres’ Black Pigments in Electrophoretic Displays

Carbon–iron oxide microspheres’ black pigments (CIOMBs) had been prepared via ultrasonic spray pyrolysis of aqueous solutions containing ferrous chloride and glucose. Due to the presence of carbon, CIOMBs not only exhibited remarkably acid resistance, but also could be well dispersed in both polar solvents and nonpolar solvent. Finally, dispersions of hollow CIOMBs in tetrachloroethylene had successfully been applied in electrophoretic displays