Spin-to-charge conversion and interface-induced spin Hall magnetoresistance in yttrium iron garnet/metallic bilayers.

We report the investigation of spin-to-charge current interconversion process in hybrid structures of yttrium iron garnet (YIG)/metallic bilayers by means of two different experimental techniques: spin pumping effect (SPE) and spin Hall magnetoresistance (SMR). We demonstrate the evidence of a correlation between spin-to-charge conversion and SMR in bilayers of YIG/Pd, YIG/Pt, and YIG/IrMn. The correlation was verified directly in the spin Hall angles and the amplitudes of the voltage signals measured by the SPE and SMR techniques. The detection of SMR was carried out using the modulated magnetoresistance technique and lock-in amplifier detection. For these measurements, we present a simple model for the interpretation of the results. The results allow us to conclude that indeed the interface in the YIG/metallic bilayers has a dominant role in the spin-to-charge current conversion and SMR.

Silicon microparticles as handles for optical tweezers experiments.

We study the behavior of silicon microparticles in a 1064 nm Gaussian-beam optical tweezers, showing that this semiconductor can be used to perform different types of optical manipulation experiments. Depending on the focal position and the laser power used, the particles can present an oscillatory dynamics in the tweezers or can be stably 3D-trapped with a trap stiffness that allows the application of femtoNewton forces with accuracy. A new, to the best of our knowledge, interpretation based on the photoexcitation of electrons in the valence band is proposed to explain the oscillations, and the quantities associated with such dynamics (e.g., amplitude, period, etc.) were characterized as a function of relevant parameters to optical tweezers setups.

FAMACHA(©) scores history of sheep characterized as resistant/resilient or susceptible to H. contortus in artificial infection challenge.

With the aim of validating the FAMACHA(©) as a method for phenotypic selection of sheep resistant/resilient to gastrointestinal nematodes, 27 Suffolk ewes with known FAMACHA(©) score histories were experimentally infected with 25,000 larvae of Haemonchus contortus. From the day of infection (day 0) to 60 days post-infection, at intervals of 7-15 days, ewes were evaluated for packed cell volume (PCV) and fecal egg counts (FEC). A statistically significant increase (p<0.05) in FEC occurred between day 0 and day 60. PCV values showed a decrease (p<0.05) starting from day 21, compared to day 0. Based on the changes in FEC and PCV values from day 0 to day 60, 15 ewes (55.56%) were classified as susceptible (S) and 12 ewes (44.44%) as resistant/resilient (RR). A comparison of the average FEC after infection between susceptible (4487.6 eggs per gram-epg) and resistant/resilient (1317.9epg) ewes showed a significant difference (p<0.05) between the two groups. The difference in average PCV values after infection (24.8% and 30.3% for S and RR, respectively) was also significant (p<0.05). Data from 980 previous evaluations of FAMACHA(©) scores from the 27 ewes showed that 58.33% of the ewes classified as RR and 46.67% of the S group had a history of only F1 and F2 scores. In the RR group, only one animal (8.33%) had an F4 score, occurring one time out of the 61 evaluations of this ewe. In contrast, 40.0% of S group ewes had F4 and/or F5 scores. During the period of FAMACHA(©) score history that was evaluated, 69.56% of the total number of anthelmintic treatments in the flock were administered to ewes from group S. Since ewes with F4 and/or F5 scores during the FAMACHA(©) score time period were classified as susceptible during the experimental infection (with the exception of one ewe), we conclude that the FAMACHA(©) score history is a useful tool for the selection of ewes that are resistant/resilient, as well as for the identification of susceptible animals that should be culled.

Spin-Current to Charge-Current Conversion and Magnetoresistance in a Hybrid Structure of Graphene and Yttrium Iron Garnet.

The use of graphene in spintronic devices depends, among other things, on its ability to convert a spin excitation into an electric charge signal, a phenomenon that requires a spin-orbit coupling (SOC). Here we report the observation of two effects that show the existence of SOC in large-area CVD grown single-layer graphene deposited on a single crystal film of the ferrimagnetic insulator yttrium iron garnet (YIG). The first is a magnetoresistance of graphene induced by the magnetic proximity effect with YIG. The second is the detection of a dc voltage along the graphene layer resulting from the conversion of the spin current generated by spin pumping from microwave driven ferromagnetic resonance into a charge current, which is attributed to the inverse Rashba-Edelstein effect.

Atorvastatin inhibits inflammatory angiogenesis in mice through down regulation of VEGF, TNF-alpha and TGF-beta1.

While compelling evidence indicates beneficial effects of statins on inflammatory processes, besides their cholesterol-lowering activities, the actions on angiogenesis are less clear-cut. Our aim was to investigate the effects of atorvastatin on key components of inflammatory angiogenesis in the murine sponge model. Polyester-polyurethane sponges, used as a framework for fibrovascular tissue growth, were implanted in Swiss mice. Atorvastatin (0.6, 3 mg/kg/day) was given orally for 8 days in drinking water. The implants collected at day 9 postimplantation were processed for the assessment of hemoglobin, myeloperoxidase (MPO), N-acetylglucosaminidase (NAG) and collagen. Relevant inflammatory, angiogenic and fibrogenic cytokines were also determined. Atorvastatin treatment resulted in significant decrease in sponge vascularization (Hb content) and in VEGF levels at both doses. Neutrophil influx (MPO activity) was not affected by the compound whereas macrophage recruitment (NAG activity) was inhibited, suggesting a degree of selectivity by atorvastatin for this cell population. The level of CCL2 (MCP1-JE) was decreased only with 0.6 mg/kg. Atorvastatin was also able to reduce collagen deposition and the levels of transforming growth factor (TGF-beta1) intraimplant, dose-dependently. The inhibitory function of atorvastatin on multiple parameters of main components of inflammatory angiogenesis revealed in this study is clearly associated with the modulatory effects of HMG-CoA reductase on VEGF, TNF-alpha and TGF-beta1 production.