Development of a low profile laser Doppler probe for monitoring perfusion at the patient – mattress interface

The clinical importance of pressure ulcers is reviewed confirming the need for continuous monitoring of skin blood perfusion at the patient – mattress interface. The design of a low profile (H≈1mm) laser Doppler probe is then described together with the experimental setup used for evaluation. The results show that the performance of the new sensor does not vary significantly from that of currently available probes over a wide range of operating parameters. The authors conclude that the sensor design provides a low cost perfusion monitoring solution with potential to significantly reduce the risk of bed sores in hospital patients

Upper Critical Fields and Critical Current Densities of Fe-based Superconductors as Compared to Those of Other Technical Superconductors

Three years since the discovery by the Hosono\u2019s group of Fe-based superconductors, an enormous number of compounds, belonging to several different families have been discovered and fundamental properties have been deeply investigated in order to clarify the interplay between magnetisms and superconductivity in these compounds. Indeed, the actual potential of these compounds for practical applications remains still unclear. Fe-based superconductors are midway between high temperature superconductors (HTSC) and MgB2. In Febased superconductors the critical current is rather independent of the field, similarly to HTSCs, as a consequence of the exceptionally high upper critical field and strong pinning associated with nm-scale local modulations of the order parameter. They exhibit low anisotropy of the critical current with respect to the crystalline directions, as in the case of MgB2, which allows current flow along the c-axis. However, Fe-based superconductor polycrystalline materials currently available still exhibit electromagnetic granularity, like the HTSCs, which suppresses superconducting current flow over long length. Whether the nature of such granularity is extrinsic, as due to spurious phases or cracks between grains or intrinsic, as related to misalignment of adjacent grains, is under debate. These aspects will be review in the light of the recent literature

Intraband vs. interband scattering rate effects in neutron irradiated MgB2

One of the most important predictions of the two-gap theory of superconductivity concerns the role of interband scattering (IBS) by impurities. IBS is expected to decrease the critical temperature, Tc, of MgB2 to a saturation value of about 20 K, where the two gaps merge to a single one. These predictions have been partially contradicted by experiments. In fact, Tc does not saturate in irradiated samples, but decreases linearly with residual resistivity and the merging of the gaps has been observed at a much lower Tc (11K). In this paper we argue that, while at low level of disorder IBS is the leading mechanism that suppresses superconductivity, at higher disorder the experimental results can only be understood if the smearing of the density of states due to intraband electron lifetime eects is considered

Some aspects of material preparation in magnesium diboride: Thin films growth and tapes fabrication

In this paper a short description of the problems related to the preparation of magnesium diboride samples in form of bulk, thin films and tapes is given. The principal problem is that Mg is highly volatile: this fact imposes severe constraints to the sample preparatation. We briefly review the activity in this field of the INFM-LAMIA laboratory. A method has been developed to prepare very clean and dense bulk samples with good transport properties in a single step, starting from pure elements. In the tapes fabrication, very promising results are obtained with a powder in tube procedure: the low cost and the good results obtained in term of critical current density make this compound interesting for the applications. The various thin film deposition techniques developed will be also shortly reviewed with particular regard to the in situ ones