Bandgap modulation of carbon nanotubes by encapsulated metallofullerenes

Motivated by the technical and economic difficulties in further miniaturizing silicon-based transistors with the present fabrication technologies, there is a strong effort to develop alternative electronic devices, based, for example, on single molecules. Recently, carbon nanotubes have been successfully used for nanometre-sized devices such as diodes, transistors, and random access memory cells. Such nanotube devices are usually very long compared to silicon-based transistors. Here we report a method for dividing a semiconductor nanotube into multiple quantum dots with lengths of about 10nm by inserting Gd@C82 endohedral fullerenes. The spatial modulation of the nanotube electronic bandgap is observed with a low-temperature scanning tunnelling microscope. We find that a bandgap of approximately 0.5eV is narrowed down to approximately 0.1eV at sites where endohedral metallofullerenes are inserted. This change in bandgap can be explained by local elastic strain and charge transfer at metallofullerene sites. This technique for fabricating an array of quantum dots could be used for nano-electronics and nano-optoelectronics.     

Functional annotation of a full-length mouse cDNA collection

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.     

Pushing the limits of lithography

The phenomenal rate of increase in the integration density of silicon chips has been sustained in large part by advances in optical lithography--the process that patterns and guides the fabrication of the component semiconductor devices and circuitry. Although the introduction of shorter-wavelength light sources and resolution-enhancement techniques should help maintain the current rate of device miniaturization for several more years, a point will be reached where optical lithography can no longer attain the required feature sizes. Several alternative lithographic techniques under development have the capability to overcome these resolution limits but, at present, no obvious successor to optical lithography has emerged.     

Role of active oxygen species in diethyldithiocarbamate-induced gastric ulcer in the rat

Diethyldithiocarbamate, an inhibitor of Cu,Zn-superoxide dismutase, was recently found to be ulcerogenic in the rat stomach, and active oxygen species were found to be responsible for its ulcerogenicity. To clarify which active oxygen species play a role in ulcerogenesis, the effects of various scavengers and iron-chelators were studied. As superoxide dismutase and catalase reduced the ulcerogenesis induced by diethyldithiocarbamate, the superoxide radical and hydrogen peroxide were considered to play a pathogenic role in this ulcer model.     

Purification of calf thymus adenosine diphosphate ribose polymerase]

Calf thymus poly ADPR polymerase has been purified to electrophoretic homogenity. The enzyme has a molecular weight of 120,000 +/- 10,000 dalton. The substrate affinity is very high (apparent Km 82.5 micrometer). The presence of exogenous DNA does not appear to be a requisite for enzymatic activity of the purified enzyme.     

Enhancement of anaphylaxis of isolated smooth muscle by adenosine phosphates and inhibition of anaphylactic mechanisms by adenosine-3′,5′-cyclic monophosphate

Zusammenfassung Zyklisches 3,5-Adenosinmonophosphat hindert in vitro die Anaphylaxis des glatten Muskels vom Meerschweinchenuterus, während Adenosin und Adenosin-5-Monophosphat die anaphylaktische Reaktion erhöhen.     

Subtypes of protein kinase C in rat cerebral microvessels

Summary Protein kinase C in rat cerebral microvessels was characterized. By hydroxyapatite column chromatography, protein kinase C in the soluble fraction was resolved into two major peaks corresponding to type II and III enzymes, in the proportions of 57% and 38%, respectively. Since each subtype is considered to have a distinct role, the high proportion of type II enzyme found in this study suggests that this type may be involved in specific functions of the cerebral microvessels.