Metal-air batteries are thought to be the ultimate solution for energy storage systems owing to their high energy density. Here we report a long-life Na-O2 battery with a high capacity of 750 mA h g(carbon)(-1) by manipulating the nucleation and growth of nano-sized NaO2 particles in a vertically aligned carbon nanotubes (VACNTs) network with a large surface area. Benefiting from the kinetically favorable formation of NaO2 reaction with a low overpotential of ~0.2 V, the electrical energy efficiency is as high as 90% for up to 100 cycles. A good rate performance (~1500 mA h g(carbon)(-1) at 667 mA g(carbon)(-1)) can be achieved through pre-deposition of a thin NaO2 layer. This study encourages the exploration of the key factors influencing the performance of metal-air batteries, as well as Na-based batteries characterized by phase transformation or conversion reactions.

To expand the toolbox of imaging in living cells, we have engineered a single-chain variable fragment binding the linear HA epitope with high affinity and specificity in vivo. The resulting probe, called the HA frankenbody, can light up in multiple colors HA-tagged nuclear, cytoplasmic, membrane, and mitochondrial proteins in diverse cell types. The HA frankenbody also enables state-of-the-art single-molecule experiments in living cells, which we demonstrate by tracking single HA-tagged histones in U2OS cells and single mRNA translation dynamics in both U2OS cells and neurons. Together with the SunTag, we also track two mRNA species simultaneously to demonstrate comparative single-molecule studies of translation can now be done with genetically encoded tools alone. Finally, we use the HA frankenbody to precisely quantify the expression of HA-tagged proteins in developing zebrafish embryos. The versatility of the HA frankenbody makes it a powerful tool for imaging protein dynamics in vivo.

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The rechargeable Li-air (or Li-O 2 ) battery with a nonaqueous electrolyte may provide a specifi c energy density above 1000 Wh kg − 1 , [ 1 , 2 ] which offers potential for achieving the target of 800 km per charge in driving future electric vehicles. As a result, it has attracted a great deal of attention recently. [ 3 − 7 ] In comparison to the cathode materials used in the Li-ion batteries which may deliver the maximum specifi c capacity of 300 mAh g − 1 , [ 8 ] the air or O 2 cathodes reported in most publications can provide the specifi c capacity as high as several thousand or even over ten thousand mAh g − 1 carbon (referring to the weight of the carbon-based materials). [ 9 , 10 ] However, the cycles are very limited when the cells are operated with such high capacity values. In order to extend the cycle operation, reduction of the depth of discharge (DOD) has been widely used. [11][12][13][14] The underlying idea is to relieve the cathode passivation by reducing coverage of the discharge products on the cathode surfaces. In contrast to the discharge, the charge process plays a role in removal of the reaction products and production of active sites for the following cycles. However, few studies have studied the infl uence of the charge reactions on the battery cyclability. [ 15 ] Considering that the carbon is normally an indispensable part of the air cathodes of Li-O 2 batteries, and the carbon-based electrodes and/or most of the currently used electrolytes are unstable upon charging above 4.0 V, [16][17][18][19] investigation of the charge cut-off voltage effect on the cycle performance is indeed necessary. As a result, in this work, we carry out a study of the cyclability of the Li-O 2 battery as a function of charge cut-off voltage. Vertically aligned carbon nanotubes (VACNTs) grown on stainless steel (SS) meshes are intentionally selected as the cathodes. Their features, including no additives and ordered confi guration, provide easy visualization of the product morphology and composition analysis of the reaction products which are deposited on the cathode surfaces. [ 6 , 9 ] The organic electrolytes, tetraethylene glycol dimethyl ether (TEGDME) and N-methyl-N-propylpiperidinium bis(trifl uoromethansulfony)imide (PP13TFSI) with LiClO 4 salts have been used in the investigated batteries. The former has been used in many researches recently. [ 4 , 10 , 11 , 15 , 17-19 ] The latter is deemed the stablest solvent of those used for the electrolytes in the Li-O 2 batteries. [ 20 ] Taking advantage of these materials, signifi cant infl uence of charge cut-off voltage on removal of reaction products on cathode surfaces is demonstrated. Consequently, the cyclability of the batteries investigated here has been greatly improved by the optimal charge cut-off voltages.Reaction mechanism and cyclability with respect to different charge reactions have been fi rstly investigated for the TEGDMEbased batteries. Figure 1 a presents the typical discharge and charge curves operated in the potential range from 2.0 t...

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A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture at 80 °C. The recrystallization of the swollen macromolecules on the fiber surface contributes to the formation of submicron protuberances, which increase the surface roughness dramatically and result in superhydrophobic behavior. The superhydrophobic PP fabrics possess excellent repellency to blood, urine, milk, coffee, and other common liquids, and show good durability and robustness, such as remarkable resistances to water penetration, abrasion, acidic/alkaline solution, and boiling water. The excellent comprehensive performance of the superhydrophobic PP fabrics indicates their potential applications as oil/water separation materials, protective garments, diaper pads, or other medical and health supplies. This simple, fast and low cost method operating at a relatively low temperature is superior to other reported techniques for fabricating superhydrophobic PP materials as far as large scale manufacturing is considered. Moreover, the proposed method is applicable for preparing superhydrophobic PP films and sheets as well.