275 research outputs found

    Point-Contact Spectroscopy on RuSr2GdCu2O8

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    We present Point-Contact experiments on polycrystalline RuSr2_2GdCu2_2O8_8 samples. The majority of tunneling curves shows a zero-bias conductance peak, which is modeled by assuming a d-wave pairing symmetry of the superconducting order parameter.The magnetic field dependence of the conductance spectra has been measured in very stable junctions. In some cases, due to the granularity of the samples, clusters of grains in series introduce peculiar features in the conductance spectra.Comment: 4 pages, 4 figures, published on Journal of Physics and Chemistry of Solid

    Point Contact Study of the Superconducting Order Parameter in RuSr2GdCu2O8

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    We have performed a detailed study of the conductance characteristics obtained by point contact junctions realized between a normal Pt/Ir tip and syntered RuSr2GdCu2O8 (Ru-1212) samples. Indeed, this compound is subject of great interest due to the coexistence of both magnetic order and bulk superconductivity. In our experiments, the low temperature tunneling spectra reproducibly show a zero bias conductance peak that can be well reproduced by a generalized BTK model in the case of d-wave symmetry of the superconducting order parameter.Comment: 3 pages, 2 figures, IJMPB style. Presented at New3SC5 Conference, China, June 200

    Pairing state in the rutheno-cuprate superconductor RuSr2GdCu2O8: A point contact Andreev Reflection Spectroscopy study

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    The results of Point Contact Andreev Reflection Spectroscopy on polycrystalline RuSr2_2GdCu2_2O8_8 pellets are presented. The wide variety of the measured spectra are all explained in terms of a modified BTK model considering a \emph{d-wave} symmetry of the superconducting order parameter. Remarkably low values of the energy gap Δ=(2.8±0.2)meV\Delta=(2.8\pm 0.2)meV and of the 2Δ/kBTc≃22\Delta/k_BT_c\simeq 2 ratio are inferred. From the temperature evolution of the dI/dVdI/dV vs VV characteristics we extract a sublinear temperature dependence of the superconducting energy gap. The magnetic field dependence of the conductance spectra at low temperatures is also reported. From the Δ\Delta vs HH evolution, a critical magnetic field Hc2≃30TH_{c_2}\simeq 30 T is inferred. To properly explain the curves showing gap-like features at higher voltages, we consider the formation of a Josephson junction in series with the Point Contact junction, as a consequence of the granularity of the sample.Comment: 8 pages, 7 EPS figures. Accepted in Phys. Rev.

    Enhancing allocentric spatial recall in pre-schoolers through navigational training programme

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    Unlike for other abilities, children do not receive systematic spatial orientation training at school, even though navigational training during adulthood improves spatial skills. We investigated whether navigational training programme (NTP) improved spatial orientation skills in pre-schoolers. We administered 12-week NTP to seventeen 4- to 5-year-old children (training group, TG). The TG children and 17 age-matched children (control group, CG) who underwent standard didactics were tested twice before (T0) and after (T1) the NTP using tasks that tap into landmark, route and survey representations. We determined that the TG participants significantly improved their performances in the most demanding navigational task, which is the task that taps into survey representation. This improvement was significantly higher than that observed in the CG, suggesting that NTP fostered the acquisition of survey representation. Such representation is typically achieved by age seven. This finding suggests that NTP improves performance on higher-level navigational tasks in pre-schooler

    Nanometal Skin of Plasmonic Heterostructures for Highly Efficient Near-Field Scattering Probes

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    In this work, atomic force microscopy probes are functionalized by virtue of self-assembling monolayers of block copolymer (BCP) micelles loaded either with clusters of silver nanoparticles or bimetallic heterostructures consisting of mixed species of silver and gold nanoparticles. The resulting self-organized patterns allow coating the tips with a sort of nanometal skin made of geometrically confined nanoislands. This approach favors the reproducible engineering and tuning of the plasmonic properties of the resulting structured tip by varying the nanometal loading of the micelles. The newly conceived tips are applied for experiments of tip-enhanced Raman scattering (TERS) spectroscopy and scattering-type scanning near-field optical microscopy (s-SNOM). TERS and s-SNOM probe characterizations on several standard Raman analytes and patterned nanostructures demonstrate excellent enhancement factor with the possibility of fast scanning and spatial resolution <12 nm. In fact, each metal nanoisland consists of a multiscale heterostructure that favors large scattering and near-field amplification. Then, we verify the tips to allow challenging nongap-TER spectroscopy on thick biosamples. Our approach introduces a synergistic chemical functionalization of the tips for versatile inclusion and delivery of plasmonic nanoparticles at the tip apex, which may promote the tuning of the plasmonic properties, a large enhancement, and the possibility of adding new degrees of freedom for tip functionalization

    Piezoelectricity and charge trapping in ZnO and Co-doped ZnO thin films

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    Piezoelectricity and charge storage of undoped and Co-doped ZnO thin films were investigated by means of PiezoResponse Force Microscopy and Kelvin Probe Force Microscopy. We found that Co-doped ZnO exhibits a large piezoelectric response, with the mean value of piezoelectric matrix element d33 slightly lower than in the undoped sample. Moreover, we demonstrate that Co-doping affects the homogeneity of the piezoelectric response, probably as a consequence of the lower crystalline degree exhibited by the doped samples. We also investigate the nature of the interface between a metal electrode, made up of the PtIr AFM tip, and the films as well as the phenomenon of charge storage. We find Schottky contacts in both cases, with a barrier value higher in PtIr/ZnO than in PtIr/Co-doped ZnO, indicating an increase in the work function due to Co-doping

    IMAGE CYTOMETRY FOR DNA ANALYSIS IN ENDOMETRIAL CARCINOMA CORRELATED WITH OTHER PROGNOSTIC PARAMETERS

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    We evaluated by static cytometry DNA ploidy parameters in 30 stage I-IV endometrial carcinomas and correlated these data with standard clinical-pathological features and disease-free period. We observed a direct correlation between either non-diploid DNA content and deeper myometrial invasion (p<0.02) or D.I.greater than or equal to 1.2 and M2-M3 tumors (p<0.009). The Kaplan Meier survival curves illustrate a more rapid relapse of disease associated with non-diploidy, high 5cExR, high level of proliferation and D.I.greater than or equal to 1.2. while Cox regression model gave relative hazards for disease recurrence of 4, 6, 3.7 and 2.1 for non-diploidy, D.I.greater than or equal to 1.2, high 5cExR and high level of proliferation respectively. This prospective study confirmed the prognostic value of DNA Index, and its usefulness in clinical practice especially in stage I cases, otherwise characterised by favourable standard prognostic factors, is discussed

    A Multistep Approach to Deal With Advanced Heart Failure: A Case Report on the Positive Effect of Cardiac Contractility Modulation Therapy on Pulmonary Pressure Measured by CardioMEMS

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    During the last years, the management of heart failure (HF) made substantial progress, focusing on device-based therapies to meet the demands of this complex syndrome. In this case report, we present a multistep approach to deal with HF. Specifically, we report the first patient subjected to the implantation of both Optimizer Smart(R) (Impulse Dynamics Inc., Marlton, NJ, USA) and CardioMEMS devices. A 72-year-old male patient with HF and reduced ejection fraction (HFrEF) was admitted to our cardiology department in January 2021, following a progressive shortening of the time between hospitalizations for levosimendan infusions. Specifically, the patient was monitored daily by CardioMEMS, and a strategy of levosimendan infusions guided by the device had been adopted. He was also a carrier of MitraClips and cardiac resynchronization therapy defibrillator (CRT-D) and had optimized HF medical therapy. In January 2021, the patient implanted Optimizer Smart(R) device for cardiac contractility modulation (CCM) therapy because of poor response to therapy and elevated pulmonary artery pressure (PAP). CCM significantly reduced PAP values following discharge (systolic PAP 33.67 &amp; PLUSMN; 2.92 vs. 40.6 &amp; PLUSMN; 3.37 mmHg, diastolic PAP 14.5 &amp; PLUSMN; 2.01 vs. 22.5 &amp; PLUSMN; 2.53 mmHg, mean PAP 22.87 &amp; PLUSMN; 2.20 vs. 30.9 &amp; PLUSMN; 2.99 mmHg, HR 60.93 &amp; PLUSMN; 1.53 vs. 80.83 &amp; PLUSMN; 3.66 bpm; p &lt; 0.0001), with persisting effect at 9 months. The usefulness of CCM is objectively demonstrated for the first time by continuous invasive monitoring of PAP by CardioMEMS, which can suggest the correct timing for CCM implantation
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