Biomedical subjects

M Calame

Publications and source records attributed to M Calame.

2 recordsLinked to original sources

PubMed2001

Collective pinning of a frozen vortex liquid in ultrathin superconducting YBa2Cu3O7 films.

The linear dynamic response of the two-dimensional (2D) vortex medium in ultrathin YBa2Cu3O7 films was studied by measuring their ac sheet impedance Z over a broad range of frequencies omega. With decreasing temperature the dissipative component of Z exhibits, at a temperature T*(omega) well above the melting temperature of a 2D vortex crystal, a crossover from a thermally activated regime involving single vortices to a regime where the response has features consistent with a description in terms of a collectively pinned vortex manifold. This suggests the idea of a vortex liquid which, below T*(omega), appears to be frozen at the time scales 1/omega of the experiments.

Journal Article↗

PubMed2001

Single-mismatch detection using gold-quenched fluorescent oligonucleotides.

Here we describe a hybrid material composed of a single-stranded DNA (ssDNA) molecule, a 1.4 nm diameter gold nanoparticle, and a fluorophore that is highly quenched by the nanoparticle through a distance-dependent process. The fluorescence of this hybrid molecule increases by a factor of as much as several thousand as it binds to a complementary ssDNA. We show that this composite molecule is a different type of molecular beacon with a sensitivity enhanced up to 100-fold. In competitive hybridization assays, the ability to detect single mismatch is eightfold greater with this probe than with other molecular beacons.

Base Pair Mismatch↗