Synthesis and Electrochemical Properties of Germanium (Ge) Nanoparticles/Multiwalled Carbon Nanotubes Composite as Anode Material for Lithium Battery

Germanium (Ge) nanoparticles/multiwalled carbon nanotubes (Ge/MWCNTs) composite is synthesized by solvothermal method combined with heat treatment under H2 atmosphere. The Ge particles are buried in MWCNTs network to form expected composite. The MWCNTs not only improve the conductivity of the composite but also act as a flexible matrix to buffer the volume change of germanium nanoparticles during the process of insertion and de-insertion in lithium ion battery system. The Ge/MWCNTs composite behaves better cycle performance and higher rate capability than those of pure germanium (Ge) nanoparticles. The Ge/MWCNTs maintained discharge capacity as 1040 mAh·g-1 after 60 cycles at the current density of 100 mA·g-1. It is a promising anode material for lithium ion battery application.

Ti-TiN Multilayer Coatings Obtained by ION FLUX Surface Modification

We present a production technology for multilayer vacuum plasma coatings with additional ion bombardment, which is implemented with two methods: by using the hollow cathode effect and by using the self-maintained discharge generated by the plasma generator. Based on this technology, a technology of producing multilayer coatings based on TiN was developed.

The maintained discharge of rat retinal ganglion cells

Action potentials were recorded from rat retinal ganglion cell fibers in the presence of a uniform field, and the maintained discharge pattern was characterized. Spike trains recorded under ketamine–xylazine anesthesia were generally stationary, while those recorded under urethane anesthesia often showed slow, undriven, quasiperiodic fluctuations in firing rate. In light of these nonstationarities, interspike interval distributions and power spectral densities are reported for data collected primarily under ketamine–xylazine. The majority of cells had multimodal interval distributions, with the first peak in the range of 25.0–38.5 ms and the subsequent peaks occurring at integer multiples of the first peak. Cells with unimodal distributions were fit well by a gamma distribution function. Interval and spike count statistics showed that ON cells tended to fire faster than OFF cells and that cells with higher rates fired in a more regular manner, with the coefficient of variation covering a wide range of values across all cells (0.43–0.97). Both ON and OFF cells show serial correlations between adjacent interspike intervals, while ON cells also showed second-order correlations. Cells with multimodal interval distribution showed a strong peak at high frequencies in the power spectra in the range of 28.9–41.4 Hz. Oscillations were present under both anesthetic conditions and persisted in the dark at a slightly lower frequency, implying that the oscillations are generated independent of any light stimulus but can be modulated by light level. The oscillation frequency varied slightly between cells of the same type and in the same eye, suggesting that multiple oscillatory generating mechanisms exist within the retina. Cells with high-frequency oscillations were described well by an integrate-and-fire model with the input consisting of Gaussian noise plus a sinusoid where the phase was jittered randomly to account for the bandwidth present in the oscillations.

Hydrogeomorphic controls on runoff in a temperate swamp

Beverly Swamp, a high-order forested temperate wetland near Hamilton, Ontario was studied during wet (2000) and dry (2001) summer seasons to determine and compare runoff pathways and storage mechanisms in two hydrogeomorphically different sub-basins. A channelized (Fletcher Swamp) and an unchannelized (Spencer Swamp) sub-basin were examined. During wet periods, the Fletcher Swamp displayed a consistent interaction between the wetland and stream, resulting in a gaining stream, maintaining a lateral hydrological connection and yielding high runoff ratios. When dry periods dominated, water tables dropped low enough in the Fletcher Swamp such that water moved from the stream channel into the underlying substrate, creating a lateral hydrological disconnection between the stream and wetland. This disconnection reduced runoff ratios during storm events. The Spencer Swamp, with no well-defined stream channel, relied on overland flow and a longitudinal hydrological connection to deliver water to the sub-basin outflow. This connection was maintained in the wet season (2000) but ceased in the dry season (2001) despite consistent inputs from an upstream reservoir. Available depression storage prevented overland flow during 2001, and although a shallow groundwater flux maintained discharge for a period of time, drought conditions led to zero discharge at the sub-basin outflow in mid-summer. Runoff ratios were reduced dramatically from season to season as a result of this disconnection. Implications of these hydrogeomorphic runoff controls on wetland biogeochemistry are discussed.

Functional properties of retinal ganglion cells during optic nerve regeneration in the goldfish

After being severed, optic axons in goldfish regenerate and eventually restore the retinotectal map; refinement of the map depends upon impulse activity generated by the ganglion cells. Because little is known about the changes in activity and receptive-field properties of ganglion cells during regeneration, we made extracellular recordings from them in the intact eye up to 95 days after sectioning their axons in the optic tract. Their receptive fields were classified as OFF-, ON–OFF-, or ON-centers, and their axonal conduction velocities measured by antidromic activation. The rate of encountering single units dropped drastically at 4–8 days postsection when only a few OFF-center units could be recorded, recovering to normal between 42 and 63 days. Receptive-field centers were normal in size, except for the few OFF-centers at 4–8 days which were abnormally large. Maintained discharge rates of all types were depressed up to 42 days, but ON–OFF-center units were more spontaneously active than normal around 42 days. Light-evoked responses in OFF-center units were subnormal at 4–8 days, becoming supernormal at 16 days and normal thereafter. ON–OFF- and ON-center units started to regain responsiveness at 16 days, and became supernormal at 42 days, before returning to normal. Conduction velocities of all fiber groups dropped to a minimum at 8 days, the fastest being affected most. There was a gradual recovery to normal conduction velocity by 63 days. The conduction latencies of OFF- and ON–OFF-center units recovered to normal by 42 days, and ON-center units by 63 days. Recovery of ganglion cell responsiveness correlates with functional recovery in the retinotectal system: OFF-center units recover light-evoked responses at about the time OFF activity first reappears in the tectum. ON- and ON–OFF-center units recover later, exhibiting supernormal spiking activity around the time that ON responses reappear in the tectum.