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A split Hopkinson pressure bar (SHPB) experiment was done to examine the feasibility and explosion resistance of high-damping rubber materials developed for use in the area of antiexplosion applications. Through the experiment, the dynamic mechanical properties of the high-damping rubber were determined. The existence of dynamic compressive stress-strain curves at various strain rates of the high-damping rubber have been confirmed from the SHPB experiment. The variation law of the dynamic compression performance with the strain rate is studied, and the energy absorption characteristics of high-damping rubber materials are analyzed. To study the microstructural changes of the high-damping rubber before and after impact, a scanning electron microscopy (SEM) test was done. The results indicated that the stress-strain curve and dynamic modulus of high-damping rubber has an obvious strain rate effect, and the strength and energy absorption ability of high-damping rubber material increases with an increase in the strain rate; the ideal energy absorption efficiency of high-damping rubber can reach 0.8 at a high strain rate and the ideal energy absorption efficiency is more than 0.5 in a wide deformation range; when compared with aluminum foam, the energy absorption effect for high-damping rubber is more apparent. In the event of a compressed deformation or the creation of holes, there may be a change in the main internal mechanism of the high buffering and energy absorption capacity of the high-damping rubber.

BackgroundRates of care abandonment for retinoblastoma (RB) demonstrate significant geographical variation; however, other variables that place a patient at risk of abandoning care remain unclear. This study aims to identify the risk factors for care abandonment across a multinational set of patients.MethodsA prospective, observational study of 692 patients from 11 RB centres in 10 countries was conducted from 1 January 2019 to 31 December 2019. Multivariate logistic regression was used to identify risk factors associated with higher rates of care abandonment.ResultsLogistic regression showed a higher risk of abandoning care based on country (high-risk countries include Bangladesh (OR=18.1), Pakistan (OR=45.5) and Peru (OR=9.23), p<0.001), female sex (OR=2.39, p=0.013) and advanced clinical stage (OR=4.22, p<0.001). Enucleation as primary treatment was not associated with a higher risk of care abandonment (OR=0.59, p=0.206).ConclusionCountry, advanced disease and female sex were all associated with higher rates of abandonment. In this analysis, enucleation as the primary treatment was not associated with abandonment. Further research investigating cultural barriers can enable the building of targeted retention strategies unique to each country.

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The epoxy syntactic foams were prepared by introducing hollow carbon microspheres (HCMs) with micro and nano-scale. Based on the surface structure analysis of HCMs, the effects of HCM content and particle size on the mechanical properties, dimensional stability, thermal conductivity, thermal stability and dielectric properties of epoxy foam were investigated. The density of the epoxy foam gradually declined with the increase of micro-scale HCM (M-HCM) content up to 9wt%, and the compression strength of epoxy foam just decreased slightly, while the compression modulus and flexural modulus were enhanced continuously. When 0.5wt% and 1wt% HCMs were involved, the reinforcing effect of nano-scale HCM (N-HCM) was superior to the M-HCMs. The compression strengthh of N-HCM/epoxy foams were almost equivalent to the neat epoxy, while the flexural strength of N-HCM samples exhibited an obvious superiority. The dimensional stability and thermal stability of epoxy foams were also improved with the addition of HCMs. Besides, the introduction of the M-HCMs and N-HCMs gave rise to the different effects on the thermal conductivity, electrical conductivity and dielectric constant of the resulting epoxy foams due to the diversity in the interfacial interaction and microstructure. These results indicate that the HCM/epoxy syntactic foams show potential application values in multifunctional materials with lightweight and high rigidity.of syntactic foam produced by mechanical dispersion of three different types of microspheres, Scotchlite TM K15 and K46 glass bubbles, and Phenoset BJO-093 hollow phenolic microspheres.The studies also revealed that the tensile, flexural, compressive strength of syntactic foam decreased with the increase of hollow particle content. Due to the inferior mechanical properties and low thermal conductivity, the application scope of the syntactic foam is limited.The diglycidyl ether of bisphenol A (DGEBA, Shell EPON ® 828) was used as epoxy matrix.Aromatic amine curing agents, including 3,3'-dimethyl-4,4'-diamino dicyclohexyl methane (DMDC) and diethyl methyl benzene diamine (DETDA), were obtained from Tianjin Synthetic Material Research Institute, China. The mixing ratio of DMDC and DETDA by weight was 1:2.The ratio of epoxy/amine in each system was equivalent stoichiometric to form completely cured

To reveal the response and damage mechanism of a tunnel across through the fracture zone under earthquake, a shaking table model test and numerical analysis were introduced, where the scale of the numerical simulation and the model test was 1:1. The tunnel acceleration response and the crack, development process, strain response characteristics and dynamic stress distribution of lining were investigated. The results show that the tunnel lining will be subjected to large tension and compressive stress, when its tensile strength is insufficient, tension fracture would generate in the bottom of the arch or near both sides of the arch foot , so reinforced concrete lining should be adopted in order to improve its ability to bear the tensile failure; the acceleration response of lining increases with the increase of input seismic acceleration; dynamic earth pressure response is more intense on both sides of the surrounding rock. This research can serve as a reference for the seismic design of the tunnel.