Results of a study of absolute threshold and duration-of-tone pulses in the bottlenosed porpoise indicated that the animal, in detecting pure-tone stimuli, integrated the acoustic energy in essentially the same way as humans. Pure-tone thresholds were determined at 0.25, 1, 4, 20, 45, and 100 kHz for a wide range of pulse durations. Least-squares fits to the data yielded time constants that were in general agreement with those obtained in experiments with humans. The data for very short pulses at 20 and 40 kHz indicated the presence of critical-frequency bands, for which rough estimates were obtained.

Masked thresholds were obtained for a bottlenosed porpoise at 15 frequencies between 5 and 100 kHz, using continuous broad-band noise to mask tonal stimuli. Critical bandwidths were calculated from the ratio of the tonal threshold level to the masking noise level per hertz at each frequency. At 5, 10, 20, 50, and 100 kHz, six different noise levels were used; from the resulting data, a plot of the amount of masking versus the effective noise level was obtained. The data are compared to those from similar experiments with human subjects. Volume 44 Number 4 1968Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 155.33.120.167 On: Fri

Masked tonal thresholds were measured for a beluga whale at one noise level and 32 frequencies between 40 Hz and 115 kHz. Critical ratios were estimated and compared with those previously measured for the bottlenose dolphin. Beluga whale critical ratios were found to be about 3 dB lower than those of the bottlenose dolphin. Absolute tonal thresholds were extended below previous measurements to 40 Hz.

Using standard operant conditioning techniques, a killer whale, Orcinus orca Linnaeus, was trained to respond to pure-tone auditory signals by pushing a response manipulandum. An audiogram was obtained for frequencies between 500 Hz and 31 kHz. Greatest sensitivity to the signal was observed at 15 kHz at a level of −70±5 dB re 1 dyn/cm2. The observed upper limit of hearing was 32 kHz. At no time during training or testing did the animal respond to an undistorted signal above 32 kHz. Frequencies below 500 Hz were not tested, owing to high ambient tank noise levels.

The authors report measurements of hard x-ray nonresonant inelastic x-ray scattering (IXS) from the Li and C 1s electrons of fully staged LiC6 Li-intercalated graphite prepared by both chemical and electrochemical methods. They find that the Li 1s orbital shifts to higher energies relative to Li metal. Relative to graphite, the C 1s IXS for LiC6 shows a shift for the σ-orbital threshold to lower energies, but no shift for the π* resonance. The findings provide bulk-sensitive evidence for substantial charge transfer from the Li intercalant to the carbon host and establish important groundwork for future in situ electrochemical studies.

In lithium ion batteries, decomposition of the electrolyte and its associated passivation of the electrode surface occurs at low potentials, resulting in an electronically insulating, but Li-ion conducting, solid electrolyte interphase (SEI). The products of the SEI and their chemical constituents/properties play an important role in the long-term stability and performance of the battery. Reactivity and the sub-keV core binding energies of lithium, carbon, oxygen, and fluorine species in the SEI present technical challenges in the spectroscopy of these compounds. Using an alternative approach, nonresonant inelastic x-ray scattering, we examine the near-edge spectra of bulk specimens of common SEI compounds, including LiF, Li(2)CO(3), LiOH, LiOH·H(2)O, and Li(2)O. By working at hard x-ray energies, we also experimentally differentiate the s- and p-symmetry components of lithium's unoccupied states using the evolution of its K edge with momentum transfer. We find good agreement with theoretical spectra calculated using a Bethe-Salpeter approach in all cases. These results provide an analytical and diagnostic foundation for better understanding of the makeup of SEIs and the mechanism of their formation.

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Carbon anodes for Li-ion cells were prepared by the in situ polymerization of olefins such as propylene and ethylene in the channels of a sepiolite clay mineral. Upon dissolution of the inorganic framework, a disordered carbon was obtained. The carbon was tested as an anode in coin cells, yielding an average reversible capacity of 633 mAh/g discounting the first cycle, which is 1.70 times higher than the capacity delivered by graphitic carbon assuming 100% efficiency. The coulombic efficiency was higher than 90%. Morphologies of the clay, carbon/clay composite, and final carbon were examined by TEM. The structure of the carbon and its electrochemical performance were monitored in situ by small angle x-ray scattering.