A micropipette system based on low driving voltage carbon nanotube actuator

Microsystem Technologies - We have fabricated a pipette system driven by a carbon nanotube (CNT) electroactive polymer (EAP) actuator, equipped with commercially available two- and three-way...     

Cell shape and chromosome partition in prokaryotes or, why E. coli is rod-shaped and haploid

In the rod-shaped cells of E. coli, chromosome segregation takes place immediately after replication has been completed. A septum then forms between the two sister chromosomes. In the absence of certain membrane proteins, cells grow instead as large, multichromosomal spheres that divide successively in planes that are at right angles to one another. Although multichromosomal, the spherical cells cannot be maintained as heterozygotes. These observations imply that, in these mutants, each individual chromosome gives rise to a separate clone of descendant cells. This suggests a model in which sites for cell division form between pairs of sister chromosomes at the time of segregation, but are not used in spherical cells until further rounds of replication have taken place, thus ensuring clonal ('hierarchical') segregation of chromosomes into progeny cells. The role of the morphogenetic membrane proteins is to convert the basically spherical cell into a cylinder that is able to divide as soon as replication and segregation have been completed, and thus to maximise the number of viable cells per genome.     

<Emphasis Type="Italic">Development and application of</Emphasis> rapid carbon determination for open-hearth control

The limitations of earlier methods of carbon determinations for open-hearth control are reviewed. A method of sampling molten steel and of preparing samples for analysis without weighing is outlined. The application of thermal conductivity cells to continuous analysis of the effluent gas from the combustion of the sample is shown to give precise and rapid results. Service experience and data indicate that the sampling and analytical system has decreased uncertainties by a factor of at least two and has permitted marked improvement in operating control. Some of the practical results of use of the system are discussed.