Data augmentation-based statistical inference of diffusion processes.

The identification of diffusion processes is challenging for many real-world systems with sparsely sampled observation data. In this work, we propose a data augmentation-based sparse Bayesian learning method to identify a class of diffusion processes from sparsely sampled data. We impute latent unsampled diffusion paths between adjacent observations and construct a candidate model for the diffusion processes with the sparsity-inducing prior on model parameters. Given the augmented data and candidate model, we investigate the full joint posterior distribution of all the parameters and latent diffusion paths under a Bayesian learning framework. We then design a Markov chain Monte Carlo sampler with non-degenerate acceptance probability on system dimension to draw samples from the posterior distribution to estimate the parameters and latent diffusion paths. Particularly, the proposed method can handle sparse data that are regularly or irregularly sampled in time. Simulations on the well-known Langevin equation, homogeneous diffusion in a symmetric double-well potential, and stochastic Lotka-Volterra equation demonstrate the effectiveness and considerable accuracy of the proposed method.

High-Strength Bio-Degradable Polymer Foams with Stable High Volume-Expansion Ratio Using Chain Extension and Green Supercritical Mixed-Gas Foaming.

The preparation of biodegradable polymer foams with a stable high volume-expansion ratio (VER) is challenging. For example, poly (butylene adipate-co-terephthalate) (PBAT) foams have a low melt strength and high shrinkage. In this study, polylactic acid (PLA), which has a high VER and crystallinity, was added to PBAT to reduce shrinkage during the supercritical molded-bead foaming process. The epoxy chain extender ADR4368 was used both as a chain extender and a compatibilizer to mitigate the linear chain structure and incompatibility and improve the foamability of PBAT. The branched-chain structure increased the energy-storage modulus (G') and complex viscosity (η*), which are the key factors for the growth of cells, by 1-2 orders of magnitude. Subsequently, we innovatively used the CO2 and N2 composite gas method. The foam-shrinkage performance was further inhibited; the final foam had a VER of 23.39 and a stable cell was obtained. Finally, after steam forming, the results showed that the mechanical strength of the PBAT/PLA blended composite foam was considerably improved by the addition of PLA. The compressive strength (50%), bending strength, and fracture load by bending reached 270.23 kPa, 0.36 MPa, and 23.32 N, respectively. This study provides a potential strategy for the development of PBAT-based foam packaging materials with stable cell structure, high VER, and excellent mechanical strength.

Improving the properties of straw biomass rattan by corn starch.

As a kind of renewable resource and natural biomass, starch has been widely used to substitute plastics in the modern industry and is regarded as one of the most promising biodegradable materials. The newly developmental rattan, straw biomass rattan (SBR) as weaving material, has been exploited as per our previous work, which possessed advantages of both natural rattan and pure plastic rattan. The main objective of the work was to improve the properties of SBR by corn starch (CS). Based on the manufacturing of the above composites, the experiments of SBR that enhanced with CS on mechanical properties, melting performance, hydroscopicity, thermogravimetric analysis, and microstructures were tested in this study. The results revealed that when the content of CS increased gradually within the range of 0, 3, 6, 9 12, and 15 wt.%, the mechanical properties and melt index of the composite both increased first and then decreased, with 6 to 12 wt.% as the optimal dosage range. In contrast, the water absorption of SBR kept increased in this range, indicating an easier biodegradable. With CS added, the microstructure of SBR was examined by scanning electron microscope and found the microscopic surfaces and sections to become smoother, and that could improve the compatibility and tenacity between the materials. As a result, CS in moderation can be used as a supplement to enhance SBR, and improve their characteristics which will enhance the mechanical properties of the composites for future perspectives.

Cation-Disordered Lithium-Excess Li-Fe-Ti Oxide Cathode Materials for Enhanced Li-Ion Storage.

Cation-disordered Li-excess lithium-transition metal (Li-TM) oxides designed based on the percolation theory are regarded as a promising new type of high-performance cathode material for Li-ion batteries. Herein, cation-disordered rocksalt-type Li-Fe-Ti oxides of Li0.89Fe0.44Ti0.45O2, Li1.18Fe0.34Ti0.45O2, and Li1.24Fe0.38Ti0.38O2 with different Li-to-transition metal ratios (Li/TM = 1, 1.49, or 1.63) are investigated to understand the effect of a Li excess on the electrochemical Li-ion storage properties. The Li excess leads to local structural fluctuations of the as-prepared Li-Fe-Ti oxides, contributing to the formation of 0-TM diffusion channels for rapid Li-ion migration. The as-prepared Li-excess Li-Fe-Ti oxide cathodes (Li/TM = 1.49 and Li/TM = 1.63) deliver a higher reversible capacity of over 220 mAh g-1 and a better rate capability compared to the Li/TM = 1 electrode, which possesses a maximum discharge capacity of only about 165 mAh g-1. The redox reactions of Fe2+/Fe3+ and O2-/O22- achieve the main capacity of the Li-excess Li-Fe-Ti oxide cathodes during cycling, as supported by 57Fe Mössbauer spectroscopy, O 1s X-ray photoelectron spectroscopy, and O K-edge soft X-ray absorption spectroscopy.