Carbon-14, derived from the testing of thermonuclear weapons in the atmosphere of the Northern Hemisphere during 1961-62, has been found in human tissues including the brain in amounts which reflect the atmospheric concentration of carbon-14 as of several months earlier. In collagen of cartilage, the rate of uptake of carbon-14 is much slower than in other tissues; essentially no radioactive carbon was found in the collagen of 70-year-old adults that had been exposed to the comparatively high concentrations of carbon-14 in the atmosphere during the years 1954 to 1964. Individuals from the Southern Hemisphere show little increase in the carbon-14 content of their tissues at present, and detailed tests with individuals traveling to the Northern Hemisphere from the Southern allow closer scrutiny of the tissue replacement rates.

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An effective strategy to lower interfacial resistance between NMC and a garnet-structured solid electrolyte with a Li2SiO3 interlayer.

Lithium garnet Li 7 La 3 Zr 2 O 12 (LLZO), with high ionic conductivity and chemical stability against a Li metal anode, is considered one of the most promising solid electrolytes for lithium−sulfur batteries. However, an infinite charge time resulting in low capacity has been observed in Li−S cells using Ta-doped LLZO (Ta-LLZO) as a solid electrolyte. It was observed that this cell failure is correlated with lanthanum segregation to the surface of Ta-LLZO that reacts with a sulfur cathode. We demonstrated this correlation by using lanthanum excess and lanthanum deficient Ta-LLZO as the solid electrolyte in Li−S cells. To resolve this challenge, we physically separated the sulfur cathode and LLZO using a poly(ethylene oxide) (PEO)-based buffer interlayer. With a thin bilayer of LLZO and the stabilized sulfur cathode/LLZO interface, the hybridized Li−S batteries achieved a high initial discharge capacity of 1307 mA h/g corresponding to an energy density of 639 W h/L and 134 W h/kg under a high current density of 0.2 mA/cm 2 at room temperature without any indication of a polysulfide shuttle. By simply reducing the LLZO dense layer thickness to 10 μm as we have demonstrated before, a significantly higher energy density of 1308 W h/L and 257 W h/kg is achievable. X-ray diffraction and X-ray photoelectron spectroscopy indicate that the PEO-based interlayer, which physically separates the sulfur cathode and LLZO, is both chemically and electrochemically stable with LLZO. In addition, the PEO-based interlayer can adapt to the stress/strain associated with sulfur volume expansion during lithiation.