RESUMO
Photolithographically defined monolithic membrane valves utilizing Fluorocur perfluoropolyether (PFPE) were fabricated and characterized to be essentially unaltered after one million actuations and exposure to the environmental stresses associated with in situ exploration of Mars.
Assuntos
Eletroforese em Microchip/instrumentação , Éteres/química , Fluorocarbonos/química , Marte , Membranas Artificiais , Voo Espacial/instrumentação , Meio AmbienteRESUMO
The amount of electronic charge transferred between gold particles and polyaniline depends not only on the electron affinity of the two materials but also on the size of the gold particles. As measured by X-ray photoelectron spectroscopy, for particles < approximately 5 nm the binding energy of the electrons is size dependent. This "nano-effect" has its origin in the electrostatics of particles. It is demonstrated as a measurable shift of the binding energy of the Au(4f7/2) photoelectrons emitted from Au particles embedded in a polyaniline matrix. Gold nanoparticle size was evaluated by high resolution transmission electron microscopy.
Assuntos
Compostos de Anilina/química , Ouro/química , Nanoestruturas/química , Compostos Organometálicos/química , Estudos de Avaliação como Assunto , Microscopia Eletrônica de Transmissão/métodos , Tamanho da Partícula , Sensibilidade e Especificidade , Espectrometria por Raios X/métodos , Propriedades de Superfície , Fatores de TempoRESUMO
Two new families of fluorescent probe, acridones and quinacridones, whose fluorescence lifetime can be altered to produce a range of lifetimes from 3 ns to 25 ns are described. Both families of fluorophore have fluorescence lifetimes which are unaffected by pH in the range of 5 to 9 and show a marked resistance to photobleaching. The probes have been modified to allow them to be attached to biomolecules and the labelling of a neuropeptide (substance P) is described. The labelled peptides have the same fluorescence lifetime as the free fluorophore. Quinacridone, with an emission around 550 nm offers a long fluorescence lifetime, photostable alternative to fluorescein.
Assuntos
Acridinas/química , Corantes Fluorescentes/química , Compostos Heterocíclicos de 4 ou mais Anéis/química , Acridinas/síntese química , Acridonas , Fluorescência , Corantes Fluorescentes/síntese química , Compostos Heterocíclicos de 4 ou mais Anéis/síntese química , Espectrometria de Fluorescência , Substância P/químicaRESUMO
The mechanical stability and viability of molecules investigated with the atomic force microscope (AFM) continue to be limiting factors in the duration of force spectroscopy measurements. In an effort to circumvent this problem, we have fabricated an all-plastic array of over 30 000 tips with dimensions similar to common AFM probes using silicon micromolding techniques. This approach enables rapid fabrication of tip arrays with improved properties, as compared to tip arrays made entirely of silicon.
