From spin-Peierls to superconductivity: (TMTTF)_2PF_6 under high pressure

The nature of the attractive electron-electron interaction, leading to the formation of Cooper-pairs in unconventional superconductors has still to be fully understood and is subject to intensive research. Here we show that the sequence spin-Peierls, antiferromagnetism, superconductivity observed in (TMTTF)_2PF_6 under pressure makes the (TM)_2X phase diagram universal. We argue that the suppression of the spin-Peierls transition under pressure, the close vicinity of antiferromagnetic and superconducting phases at high pressure as well as the existence of critical antiferromagnetic fluctuations above T_c strongly support the intriguing possibility that the interchain exchange of antiferromagnetic fluctuations provides the pairing mechanism required for bound charge carriers.Comment: 4 pages, revtex, 4 figures (jpeg,eps,png

A Comparative Study of the Effectiveness of Adaptive Filter Algorithms, Spectral Kurtosis and Linear Prediction in Detection of a Naturally Degraded Bearing in a Gearbox

Diagnosing bearing faults at the earliest stages is critical in avoiding future catastrophic failures. Many techniques have been developed and applied in diagnosing bearings faults; however, these traditional diagnostic techniques are not always successful when the bearing fault occurs in gearboxes where the vibration response is complex; under such circumstances, it may be necessary to separate the bearing signal from the complex signal. In this paper, an adaptive filter has been applied for the purpose of bearing signal separation. Four algorithms were compared to assess their effectiveness in diagnosing a bearing defect in a gearbox, least mean square (LMS), linear prediction, spectral kurtosis and fast block LMS. These algorithms were applied to decompose the measured vibration signal into deterministic and random parts with the latter containing the bearing signal. These techniques were applied to identify a bearing fault in a gearbox employed for an aircraft control system for which endurance tests were performed. The results show that the LMS algorithm is capable of detecting the bearing fault earlier in comparison with the other algorithms

Dielectric response of charge induced correlated state in the quasi-one-dimensional conductor (TMTTF)2PF6

Conductivity and permittivity of the quasi-one-dimensionsional organic transfer salt (TMTTF)2PF6 have been measured at low frequencies (10^3-10^7 Hz) between room temperature down to below the temperature of transition into the spin-Peierls state. We interpret the huge real part of the dielectric permittivity (up to 10^6) in the localized state as the realization in this compound of a charge ordered state of Wigner crystal type due to long range Coulomb interaction.Comment: 11 pages, 3 .eps figure

Sex differences in the association between major risk factors and the risk of stroke in the UK Biobank cohort study

Objective: To determine whether there are sex differences in the association between risk factors and incident stroke, including stroke subtypes. Methods: A total of 471,971 (56% women) UK Biobank participants without a history of cardiovascular disease were included. During 9 years of follow-up, 4,662 (44% women) cases of stroke were recorded. Cox models yielded adjusted hazard ratios (HRs) and women-to-men ratios of HRs (RHRs) for stroke associated with 7 risk factors. Results: The incidence rate per 10,000 person-years was 8.66 (8.29-9.04) in women and 13.96 (13.44-14.50) in men for any stroke, 6.06 (5.75-6.38) in women and 11.35 (10.88; 11.84) in men for ischemic stroke, and 1.56 (1.41-1.73) in women and 2.23 (2.02-2.45) in men for hemorrhagic stroke. The association between increases in blood pressure, body anthropometry, and lipids, diabetes, and atrial fibrillation and any stroke was similar between men and women. Hypertension, smoking, and a low socioeconomic status were associated with a greater HR of any stroke in women than men; the RHRs were 1.36 (1.26-1.47), 1.18 (1.02-1.36), and 1.17 (1.03-1.33), respectively. Diabetes was associated with a higher HR of ischemic stroke in women than men (RHR 1.25 [1.00-1.56]). Atrial fibrillation was associated with a higher HR of hemorrhagic stroke in women than men (RHR 2.80 [1.07-7.36]). Conclusion: Several risk factors are more strongly associated with the risk of any stroke or stroke subtypes in women compared with men. Despite this, the incidence of stroke remains higher among men than women

Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils

The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in $^{208}$Tl and $^{214}$Bi for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8 $m^2$ of sensitive surface area, has been running in the Modane Underground Laboratory since February, 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in $^{208}$Tl. After more than one year of background measurement, a surface activity of the scintillators of $\mathcal{A}$($^{208}$Tl) $=$ 1.5 $\mu$Bq/m$^2$ is reported here. Given this level of background, a larger BiPo detector having 12 m$^2$ of active surface area, is able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of $\mathcal{A}$($^{208}$Tl) $<$ 2 $\mu$Bq/kg (90% C.L.) with a six month measurement.Comment: 24 pages, submitted to N.I.M.

On the effect of ultrasound-assisted atmospheric freeze-drying on the antioxidant properties of eggplant

[EN] The low operating temperatures employed in atmospheric freeze-drying permits an effective drying of heat sensitive products, without any impairment of their quality attributes. When using power ultrasound, the drying rate can be increased, thus reducing the process duration. However, ultrasound can also affect the product quality. The aim of this study was to evaluate the effect of various drying process variables, namely air temperature and velocity, ultrasound power and sample size, on the antioxidant properties of eggplant (Solanum Melongena L.) samples. For this reason, drying experiments were carried out at different drying temperatures (-5, -7.5, -10 °C), power ultrasound levels (0, 25, 50 W; 21.9 kHz) and air velocities (2, 5 m s-1) using different sample sizes (8.8 mm and 17.6 mm cube side). The ascorbic acid content (Jagota and Dani method), total phenolic content (Folin-Ciocalteau method), and the antioxidant capacity (FRAP method) of the dried products were considered as quality indicators of the dried samples. The increase in air velocity and temperature, as well as the sample size, significantly reduced the antioxidant potential of the dried samples (p-value < 0.05). For a given sample size, the application of ultrasound, at the acoustic power levels tested, did not produce significant effects on the antioxidant indicators considered. Temperature measurements inside the drying sample showed a non-negligible temperature rise when acoustic power was applied.The authors acknowledge the financial support from Generalitat Valenciana (PROMETEOII/2014/005) and INIA-ERDF (RTA2015-00060-C04-02).Colucci, D.; Fisore, D.; Rosselló, C.; Carcel Carrión, JA. (2018). On the effect of ultrasound-assisted atmospheric freeze-drying on the antioxidant properties of eggplant. Food Research International. 106:580-588. https://doi.org/10.1016/j.foodres.2018.01.022S58058810