Spin flip scattering at Al surfaces

Non-local measurements are performed on a multi terminal device to $in-situ$ determine the spin diffusion length and in combination with resistivity measurements also the spin relaxation time in Al films. By varying the thickness of Al we determine the contribution to spin relaxation from surface scattering. From the temperature dependence of the spin diffusion length it is established that the spin relaxation is impurity dominated at low temperature. A comparison of the spin and momentum relaxation lengths for different thicknesses reveals that the spin flip scattering at the surfaces is weak compared to that within the bulk of the Al films.Comment: 11 pages, 5 figure

Enhanced spin accumulation in a superconductor

A lateral array of ferromagnetic tunnel junctions is used to inject and detect non-equilibrium quasi-particle spin distribution in a superconducting strip made of Al. The strip width and thickness is kept below the quasi particle spin diffusion length in Al. Non-local measurements in multiple parallel and antiparallel magnetic states of the detectors are used to in-situ determine the quasi-particle spin diffusion length. A very large increase in the spin accumulation in the superconducting state compared to that in the normal state is observed and is attributed to a diminishing of the quasi-particle population by opening of the gap below the transition temperature.Comment: 6 pages, 4 figures; accepted for publication in Journal of Applied Physic

Spin injection and relaxation in a mesoscopic superconductor

We study spin accumulation and spin relaxation in a superconducting nanowire. Spins are injected and detected by using a set of magnetic tunnel contact electrodes, closely spaced along the nanowire. We observe a giant enhancement of the spin accumulation of up to five orders of magnitude on transition into the superconducting state, consistent with the expected changes in the density of states. The spin relaxation length decreases by an order of magnitude from its value in the normal state. These measurements combined with our theoretical model, allow us to distinguish the individual spin flip mechanisms present in the transport channel. Our conclusion is that magnetic impurities rather than spin-orbit coupling dominate spin-flip scattering in the superconducting state.Comment: 5 pages, 5 figure

The pandemic curvature of democratic space/time. A legal perspective.

The paper outlines if and how the pandemic contributed to the curvature of the democratic space/time. The entire legal toolbox was deployed and shaped to counter the pandemic's many impacts: not only regulatory strategies and decision-making processes, but also governance and even the legal lexicon. The short distance travelled in the journey towards recovery and resilience - which per se is a pandemic output - has already revealed the goal-oriented and performative face of the new NRRP/dedicated governance and regulatory framework, which seems able to temper the future and the risks it brings. It also paves the way to longer journeys, including the big transitions of our time - environmental and digital transitions, but also cultural and social ones - together with their transformative potential. Democracy is at a crossroad: it has the opportunity to be fit for the future (future-proof), or simply lost in transition(s). In this respect a few lessons emerge from the pandemic

QCD

We discuss QCD studies that will be possible at LEP2. We examine both experimental and theoretical aspects of jets, fragmentation functions, multiplicities and particle spectra.Comment: 44 pages, Latex, epsfig, 18 figures, to appear on the Report of the Workshop on Physics at LEP2, CERN 96-01, vol. 1, 199

Improvement in the sustainability and stability of acrylic protective coatings for outdoor bronze artworks

Outdoor bronze artworks are an entrenched part of our urban landscape. They are usually covered by a patina resulting from their exposition to the environment. This patina plays an important aesthetic role and may provide some passivation on the surface, nonetheless it does not prevent the degradation processes promoted by external factors such as pollution, light and humidity. One of the strategies to slow down these unwanted processes is the application of protective coatings. The products currently available have some limitations due to the loss of effectiveness over time and poor environmental sustainability. With the aim of proposing more performing alternatives, coatings based on Paraloid (R) B44 modified with corrosion inhibitors and light stabilizers were prepared and characterized. Two non-toxic corrosion inhibitors were studied, 5-mercapto-1-pheniltetrazole (MPT) and 5-ethyl-1,3,4-thiadiazol-2-amine (AEDTA), comparing them with the traditional benzotriazole (BTA). The approach used aimed to identify the blend providing the most stable coatings. The chemical and physical properties of the coatings, such as colour, solubility, glass transition and composition, were studied and monitored over time. All coatings have shown adequate visual properties; however, corrosion inhibitors degrade some other properties of the coatings and need to be used in conjunction with light stabilizers. The permanence of corrosion inhibitors in the coatings over time was also studied by investigating the role of the support. The establishment of specific interactions between inhibitors and the bronze surface lengthens their permanence in the coatings compared to what happens with inert supports. Especially for AEDTA, the inhibitor retention within the coating and at the coating-bronze interface is better than for BTA and MPT. The effect of each of the additives on the photooxidation stability of the coating was evaluated and the most promising inhibitor and stabilizer combination was identified

Experimental infection with Yersinia pseudotuberculosis in European brown hare (Lepus europaeus, Pallas)

Objective To investigate clinicopathological, bacteriological and pathological aspects of an experimental infection with Yersinia pseudotuberculosis (Y. pseudotuberculosis) in hares to verify the efficacy of serology for the in vivo diagnosis. Moreover, the pathogenicity of two Y. pseudotuberculosis strains was investigated in order to detect potential differences. Methods Twelve European brown hares (Lepus europaeus, Pallas) were experimentally infected per os and via conjunctival mucosae with Y. pseudotuberculosis: six subjects were infected with a strain isolated from a naturally infected hare (YpH) and six subjects with a strain isolated from a naturally infected rabbit (YpR). Two hares were used as negative controls. All animals were subjected to clinical, bacteriological and serological examinations during 9 weeks following the infection and, at the end of the control period, subjects still alive were euthanized and submitted to a complete post mortem examination. Results All faecal samples collected during the control period were positive for bacteriological examinations and to a PCR for the inv gene of Y. pseudotuberculosis, while only one YpH-infected hare showed a positive haemocultures. From the 2nd to the 9th week post infection (pi), serological analysis revealed specific antibodies with titers ranging from 1:10 to 1:160 in all YpH-infected and two YpR-infected subjects. All the YpH-infected and two YpR-infected hares scored positive for Y. pseudotuberculosis by means of bacteriological investigations. Grossly, suppurative multifocal lesions were detected in liver, spleen, kidney and sub-mandibular lymph nodes in both YpH- and YpR-infected hares and confirmed with histopathology. Pulmonary lesions were observed only in YpH-infected subjects. Immunohistochemistry confirmed the presence of bacterial antigen in all infected animals. Conclusion Results of this study revealed that YpH strain is more pathogenic for hares than the YpR strain; moreover the serological test performed in this study could be used for the diagnosis of pseudotuberculosis in hares, whereas post mortem diagnosis should be confirmed by means of bacteriological examination, PCR, histopathology and immunohistochemistry

Triterpenoids from vitellaria paradoxa stem barks reduce nitrite levels in lps-stimulated macrophages

open7siVitellaria paradoxa C. F. Gaertn is widely used in African traditional medicine as an anti-inflammatory remedy to treat rheumatism, gastric problems, diarrhea, and dysentery. The phyto-chemical investigation of the ethyl acetate extract of V. paradoxa stem bark collected in Burkina Faso led to the isolation of eight known and two triterpenes undescribed to date (7 and 10), in the free alcohol form or as acetyl and cinnamyl ester derivatives. The stereostructures of the new compounds were elucidated using HR-ESIMS and 1D and 2D NMR data. The isolated compounds were evaluated in vitro for their inhibitory effect on nitrite levels on murine macrophages J774 stimulated with the lipopolysaccharide (LPS). Among all the compounds tested, lupeol cinnamate (3) and betulinic acid (5) showed a beneficial effect in reducing nitrite levels produced after LPS stimulation.openSirignano C.; Nadembega P.; Poli F.; Romano B.; Lucariello G.; Rigano D.; Taglialatela-Scafati O.Sirignano C.; Nadembega P.; Poli F.; Romano B.; Lucariello G.; Rigano D.; Taglialatela-Scafati O