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Volume 30, Number 1, March 2010 OLAC Newsletter

Digitized March 2010 issue of the OLAC Newsletter

Volume 30, Number 2, June 2010 OLAC Newsletter

Digitized June 2010 issue of the OLAC Newsletter

Volume 30, Number 3, September 2010

Digitized September 2010 issue of the OLAC Newsletter

Volume 30, Number 4, December 2010

Digitized December 2010 issue of the OLAC Newsletter

Electrochemical Characterization of Films of Single-Walled Carbon Nanotubes and Their Possible Application in Supercapacitors

Films of single-wall carbon nanotubes (SWCNTs) were cast from suspensions in several solvents on the surface of a Pt or Au electrode. Cyclic voltammetry of the films in MeCN did not show well-resolved waves (as distinct from films of C_(60) prepared in a similar manner). However, the increase in the effective capacitance of the electrode with a SWCNT film at 0.5 V vs. an AgQRE was 283 F/g, which is about twice that of carbon electrodes in nonaqueous solvents

Volume 29, Number 1, March 2009 OLAC Newsletter

Digitized March 2009 issue of the OLAC Newsletter

What can the activation energy tell about the energetics at grain boundaries in polycrystalline organic films?

Charge-carrier transport at the semiconductor-gate dielectric interface in organic field-effect transistors is critically dependent on the degree of disorder in the typically semi-crystalline semiconductor layer. Charge trapping can occur at the interface as well as in the current-carrying semiconductor layer itself. A detailed and systematic understanding of the role of grain boundaries between crystallites and how to avoid their potentially detrimental effects is still an important focus of research in the organic electronics community. A typical macroscopic measurement technique to extract information about the energetics of the grain boundaries is an activation energy measurement. Here, we compare detailed experiments on the energetic properties of monolayer thin films implemented in organic field-effect transistors, having controlled numbers of grain boundaries within the channel region to kinetic Monte-Carlo simulations of charge-carrier transport to elucidate the influence of grain boundaries on the extracted activation energies. Two important findings are: 1) whereas the energy at the grain boundary does not change with the number of grain boundaries in a thin film, both the measured and simulated activation energy increases with the number of grain boundaries. 2) In simulations where both energy barriers and valleys are present at the grain boundaries there is no systematic relation between the number of grain boundaries and extracted activation energies. We conclude, that a macroscopic measurement of the activation energy can serve as general quality indicator of the thin film, but does not allow microscopic conclusions about the energy landscape of the thin film

Intrinsic Circadian Clock of the Mammalian Retina: Importance for Retinal Processing of Visual Information

SummaryCircadian clocks are widely distributed in mammalian tissues, but little is known about the physiological functions of clocks outside the suprachiasmatic nucleus of the brain. The retina has an intrinsic circadian clock, but its importance for vision is unknown. Here we show that mice lacking Bmal1, a gene required for clock function, had abnormal retinal transcriptional responses to light and defective inner retinal electrical responses to light, but normal photoreceptor responses to light and retinas that appeared structurally normal by light and electron microscopy. We generated mice with a retina-specific genetic deletion of Bmal1, and they had defects of retinal visual physiology essentially identical to those of mice lacking Bmal1 in all tissues and lacked a circadian rhythm of inner retinal electrical responses to light. Our findings indicate that the intrinsic circadian clock of the retina regulates retinal visual processing in vivo