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Nanocomposites have been demonstrated as potential materials for biosensors to biomedicine applications. However, the crystallization mechanism of nanocomposites has not been thoroughly investigated so far. Cellulose nanofiber is used as a new kind of nano-filler to modify the biodegradable polymer to prepare nanocomposites. Banana cellulose nanofibers/polycaprolactone composite membranes (BNCF/PCL) and banana cellulose nanofibers grafted with polycaprolactone/polycaprolactone composite membranes (BGCL/PCL) were prepared, respectively. To explore the effects of BNCF and BGCL on the crystallization properties of PCL. SEM, POM, and DSC were used to study the crystallization of PCL, BNCF/PCL, and BGCL/PCL films. Mo's method was applied to study the non-isothermal kinetics of BNCF/PCL films, Avarmi and Jeziorny's models successfully predict the non-isothermal kinetics of BGCL/PCL films. The results showed that BNCF promoted the crystallization of BNCF/PCL films. The crystallization peak temperature of BNCF/PCL films was 4.11 ℃ higher than pure PCL, and the crystallinity was 5.34% higher than that of pure PCL. The crystallization peak temperature of the BGCL/PCL films decreased slightly, but the crystallinity increased by 3.78%. The crystal growth modes of BNCF/PCL films and BGCL/PCL films were consistent with the three-dimensional growth of heterogeneous nucleation, BNCF/PCL films with average Avrami index n ranging from 2.7 to 3.9, and the BGCL/PCL films with n ranging from 2.5 to 3.2. Furthermore, the micrographs of polarized optical microscopy (POM) supported the kinetics results. This study makes a deep insight into the effect of cellulose nanofiber on the crystallization of biodegradable aliphatic polyesters. [ABSTRACT FROM AUTHOR]

Nutrient fluxes at the sediment–water interface are essential for water quality and aquatic ecosystems. In this study, a unified expression for the sediment nutrient flux under different controlling modes is proposed by analytically solving the first-order linear partial differential equations describing nutrient transport in the sediment layer and overlying water. In particular, the analytical expression for the sediment nutrient flux due to bedform migration is derived, and the effects of bedform parameters, water depth, and sediment size are explored. With increasing flow velocity, the controlling mode of the sediment nutrient flux changes from diffusion to sand wave motion and then bed erosion, resulting in a significant increase in the flux. The water depth and sediment size indirectly affect the sediment nutrient flux by changing the critical velocity and the dimension and migration velocity of the sand waves. The physical meaning of each term of the analytical solution can be distinguished, which is beneficial for exploring the flux exchange at the sediment–water interface in mobile beds. [ABSTRACT FROM AUTHOR]

Bearing failure is one of the most important factors influencing performance, accuracy and reliability of rotating machineries. Bearing faults are commonly shown as the defects such as rolling body fracture, rolling body, and surface pitting, etc. Dynamic model of 6206 deep groove ball bearing with the above-mentioned bearing faults has been established by finite element method. Exponent Hardening Plasticity Cowper Symonds model related to strength and hardening coefficients is adopted for describing elastoplastic material model of rolling body. The smaller difference between simulated results obtained by EDM and theoretical results calculated by Hertzian point contact theory validates the reliability of explicit dynamic model established in this paper. Dynamic contact characteristics of rolling bearing with different faults such as rolling body fracture, rolling body peeling, and bearing pitting are investigated using explicit dynamic model above. By comparing contact characteristics of fault bearing with those of fault-free bearing, it provides a reference for fault diagnosis and failure prevention of rolling bearing. [ABSTRACT FROM AUTHOR]