We present an experimental study of the transport properties of a ferromagnetic metallic wire (Co) in metallic contact with a superconductor (Al). As the temperature is decreased below the Al superconducting transition, the Co resistance exhibits a significant dependence on both temperature and voltage. The differential resistance data show that the decay length for the proximity effect is much larger than we would simply expect from the exchange field of the ferromagnet. 74.50.+r, 74.80.Fp, 85.30St Superconducting proximity effect consists in inducing superconductive properties in a non-superconducting metal. Although this effect has been studied for a long time 1 , it has gained some renewed interest due to recent experiments performed on samples of mesoscopic size. In such samples, the electron phase-breaking length L ϕ is larger than the sample length L. One can thus probe experimentally the characteristic energy scale of the proximity effect ǫ c =hD/L 2 , which is the Thouless energy related to the sample length. This has led for instance to the observation of large magnetoresistance oscillations in normal metal (N) loops in contact with a superconducting (S) island 2-4 . These oscillations provide a direct evidence for the long-range (up to L ϕ ) nature of the proximity effect. Another recent and striking result is the reentrant behaviour. The excess conductance induced by proximity effect is maximum at a temperature or a bias voltage equivalent to the sample Thouless energy 5 , but the normal state conductance reappears at lower energy.Most experiments were performed in noble metals or semiconductor 2D electron gas, where electron interactions are negligible. In a free electron model, the zerotemperature, zero-bias resistance of a mesoscopic metallic wire is predicted to recover the normal state value 6-8 . In the presence of interactions, theoretical studies 7,9 predict a severe modification of the transport properties. Attractive (respectively repulsive) electron-electron interactions are believed to result in a resistance lower (respectively higher) than the normal-state one 7 . This could provide a probe for interactions in normal metals like Au, Ag, etc 10 . In this communication, we present an experimental study of the superconducting proximity effect in a ferromagnetic metal (F). Magnetic metals are in the strong interaction limit. Exchange interactions between electrons in a ferromagnet usually lead to efficient Cooperpair breaking in F-S structures. However, it is worthwhile re-examining the actual proximity effect in a small ferromagnetic wire 11 . Some experiments 12,13 suggested long-range coherence effects, but without any clear conclusion.

Crystals of the three Bi-based cuprates of general formula Bi2Sr2Ca, -&Cu"O~with n 1, 2, and 3 have been isolated and their structural and physical properties investigated. The structures are similar, diR'ering only in the number of Cu02-Ca-Cu02 slabs packed along the c axis. The insertion of one and two slabs increases c from 24.6 to 30.6 and 37.1 A. Transmission electron microscopy shows there are stacking faults within the crystals in agreement with our x-ray data and its analysis. Resistivity, ac susceptibility, and dc magnetization measurements demonstrate superconductivity in the n 1, 2, and 3 phases at 10, 85, and 110 K, respectively. The observed transition temperatures and the stacking fault densities are dependent upon sample processing, in particular, the annealing temperatures and cooling rates. The transition temperature is, within the accuracy of our chemical titration, independent of the average copper valency that was determined to be 2.15+'0.03 for each of the three compounds.

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Superconducting critical transitions with an onset at 112 K and zero resistance at 107 K are obtained within the Bi-Sr-Ca-Cu-0 system. The synthesis and formation of the 110-K superconducting phase using the 85-K material as a precursor is explained. The 110-K phase grows from the 85-K phase such that the resulting faceted crystal (a pseudomorph)

Results suggest there is room for improvement in choice of agents prescribed. We propose additional education and training of clinicians to improve adherence to clinical practice guidelines.