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The laws governing life should be as simple as possible; however, theoretical investigations into allometric laws have become increasingly complex, with the long-standing debate over the scaling exponent in allometric laws persisting. This paper re-examines the same biological phenomenon using two different scales. On a macroscopic scale, a cell surface appears smooth, but on a smaller scale, it exhibits a fractal-like porous structure. To elaborate, a few examples are given. Employing the two-scale fractal theory, we theoretically predict and experimentally verify the scaling exponent values for basal, active, and maximal metabolic rates. This paper concludes that Rubner's 2/3 law and Kleiber's 3/4 law are two facets of the same truth, manifested across different scale approximations. [ABSTRACT FROM AUTHOR]

Twisted artificial muscles based on natural fibers are of special interest in diverse fields. However, current research is limited either by the material itself, or by the preparation methods requiring complex processing or specialized equipment. In this study, a facile and green method is introduced to prepare hair artificial muscles with extremely large tensile stroke and fast recovery. The maximum tensile stroke for the hair artificial muscles upon water actuation is as large as 10 000% and the large‐stroke muscles can recover fast in ethanol. In addition, these hair artificial muscles maintain their excellent performance after either 100 water–ethanol stimulation cycles or staying in open air for 5 months. Moreover, the hair artificial muscle is able to contract by 59% when lifting 10 times its own weight, pull a wheel model or climb a long distance under water, and work as a smart water‐sensitive switch. This work provides new insights into the development of simpler and more environmentally friendly methods for preparing advanced natural fiber‐based artificial muscles that have broad applications in soft robotics and biomedical engineering. An interactive preprint version of the article can be found here: https://doi.org/10.22541/au.167385630.01748766/v1. [ABSTRACT FROM AUTHOR]

Superhydrophobic cellulose-based products show tremendous potential applications in both industries and researches owing to their inherent biodegradability, non-toxicity, and cost-effectiveness. However, previous studies mainly focused on superhydrophobic cellulose bulk materials rather than universal cellulose powder. Though some methods have been proposed for preparing superhydrophobic cellulose powder, their fabricating processes involve plenty of high-toxic organic solvents. In this work, we proposed a facile one-step solvent-free method to prepare superhydrophobic cellulose powder. The modified cellulose powder shows not only superhydrophobicity but also reversible wettability. Moreover, the superhydrophobic cellulose shows immense UV resistance by enduring 60 h UV radiation. The superhydrophobic cellulose powder-coated cotton fabric could separate oil/water mixture with high efficiency and reusability. This work provides a green method to produce superhydrophobic cellulose powder which can be used as a raw material for sophisticated multifunctional material fabrication in future. • A solvent-free method was proposed for fabricating superhydrophobic cellulose particles. • The superhydrophobic cellulose particles show reversible wettability. • The superhydrophobic cellulose particles show high stability against UV radiation. [ABSTRACT FROM AUTHOR]