One great challenge in understanding the history of life is resolving the influence of environmental change on biodiversity. Simulated annealing and genetic algorithms were used to synthesize data from 11,000 marine fossil species, collected from more than 3000 stratigraphic sections, to generate a new Cambrian to Triassic biodiversity curve with an imputed temporal resolution of 26 ± 14.9 thousand years. This increased resolution clarifies the timing of known diversification and extinction events. Comparative analysis suggests that partial pressure of carbon dioxide (Pco2) is the only environmental factor that seems to display a secular pattern similar to that of biodiversity, but this similarity was not confirmed when autocorrelation within that time series was analyzed by detrending. These results demonstrate that fossil data can provide the temporal and taxonomic resolutions necessary to test (paleo)biological hypotheses at a level of detail approaching those of long-term ecological analyses.

Natural fibers in micro and nano scales may be a potential alternative for man-made fibers because of the comparable mechanical properties to those of glass, carbon, and aramid fibers. Cellulose fibril and fibril aggregate are generally prepared by physical treatments, e.g., high-pressure homogenizer, or chemical treatments, e.g., acid hydrolysis. In this study, fibril aggregates were generated from a regenerated cellulose fiber by a novel mechanical treatment. The geometrical characteristics of the fibers and the fibril aggregates were investigated using scanning electron microscopy (SEM) and polarized light microscopy (PLM), and its crystallinity was investigated by wide angle X-ray diffraction (WAXD). The degree of fibrillation of the fibers was indirectly evaluated by water retention value (WRV). Nano-biocomposites reinforced with fibril aggregates were prepared by film casting and compression molding and evaluated by tensile test. The morphological characteristics of the nanocomposites were investigated with SEM and PLM. As reference, commercial microfibrillated cellulose was also used to reinforce biodegradable polymer.

Cellulose fibrils of microscale and nanoscale sizes have great strength and hence furnish the possibility of reinforcing polymers. Fibrils can be isolated from natural cellulose fibers by chemical or mechanical methods. However, the existing procedures either produce low yields or severely degrade the cellulose and, moreover, are not environment friendly or energy efficient. The purpose of this study was to develop a novel process that uses high-intensity ultrasonication (HIUS) to isolate fibrils from several cellulose resources. Six factors that may affect the efficiency of fibrillation, including power, temperature, time, concentration, size, and distance, have been considered and discussed. HIUS treatment can produce very strong mechanical oscillating power; therefore, the separation of cellulose fibrils from its biomass is possible by the action of hydrodynamic forces of the ultrasound. Water-retention value and volume change were used to evaluate and optimize the process parameters. The degree of fibrillation of the cellulose fibers treated by HIUS was significantly increased.

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High-intensity ultrasonication with a batch process was used to isolate fibrils from several cellulose sources, and a mixture of microscale and nanoscale fibrils was obtained. The geometrical characteristics of the fibrils were investigated with polarized light microscopy, scanning electron microscopy, and atomic force microscopy. The results show that small fibrils with diameters ranging from about 30 nm to several micrometers were peeled from the fibers. Some fibrils were isolated from the fibers, whereas some were still on the fiber surfaces. The lengths of untreated and treated cellulose fibers were investigated by a fiber size analyzer. The crystallinities of some cellulose fibers were evaluated by wide-angle X-ray diffraction and Fourier transform infrared spectroscopy. The high-intensity ultrasonication technique is an environmentally benign method and a simplified process that conducts fiber isolation and chemical modification simultaneously and helps significantly reduce the production cost of cellulose nanofibers and their composites.