Nature of non-magnetic strongly-correlated state in delta-plutonium

Ab-initio relativistic dynamical mean-field theory is applied to resolve the long-standing controversy between theory and experiment in the "simple" face-centered cubic phase of plutonium called delta-Pu. In agreement with experiment, neither static nor dynamical magnetic moments are predicted. In addition, the quasiparticle density of states reproduces not only the peak close to the Fermi level, which explains the large coefficient of electronic specific heat, but also main 5f features observed in photoelectron spectroscopy.Comment: 9 pages, 3 figure

A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15-1.73 GHz

We conducted a search for narrowband radio signals over four observing sessions in 2020-2023 with the L-band receiver (1.15-1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of ~11,680 stars and planetary systems in the ~9 arcminute beam of the telescope. All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. In this work, we also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable frequency range of the receiver and 98.7% of the injections when regions of dense RFI are excluded. In another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ~15 times smaller at ~6%. The pipeline efficiency affects calculations of transmitter prevalence and SETI search volume. Accordingly, we developed an improved Drake Figure of Merit and a formalism to place upper limits on transmitter prevalence that take the pipeline efficiency and transmitter duty cycle into account. Based on our observations, we can state at the 95% confidence level that fewer than 6.6% of stars within 100 pc host a transmitter that is detectable in our search (EIRP > 1e13 W). For stars within 20,000 ly, the fraction of stars with detectable transmitters (EIRP > 5e16 W) is at most 3e-4. Finally, we showed that the UCLA SETI pipeline natively detects the signals detected with AI techniques by Ma et al. (2023).Comment: 22 pages, 9 figures, submitted to AJ, revise

High Pressure Study of Pu0.92Am0.08 Binary Alloy

The phase transitions (by means of x-ray diffraction) and electrical resistivity of a Pu0.92Am0.08 binary alloy were determined under pressure (up to 2 GPa). The evolution of atomic volume with pressure gives detailed information concerning the degree of localization of 5f electronic states and their delocalization process. A quasi-linear V = f (P) dependence reflects subtle modifications of the electronic structure when P increases. The electrical resistivity measurements reveal the very high stability of the d phase for pressures less than 0.7 GPa, since no martensitic-like transformation occurs at low temperature. Remarkable electronic behaviours have also been observed. Finally, resistivity curves have shown the temperature dependence of the phase transformations together with unexpected kinetic effects.JRC.E.6-Actinides researc

Structural Investigation of Delta-stabilized Plutonium Alloys under Pressure

see attachmentJRC.E.6-Actinides researc

Reliable quantification of bisphenol A and its chlorinated derivatives in human urine using UPLC-MS/MS method

International audienceBisphenol A (BPA), a widespread man-made chemical classified as an endocrine disruptor, is increasingly considered as a major cause of concern for human health. Chlorine present in drinking water may react with BPA to form chlorinated derivatives (ClxBPA), which have demonstrated a heightened level of estrogenic activity. If many epidemiological studies report that more than 90% of people have detectable BPA levels in their urine, then no such study has been undertaken regarding ClxBPA. The purpose of this work is to propose a highly sensitive and accurate analytical method adapted to large-scale biomonitoring studies aimed at assessing exposure to BPA and ClxBPA through the use of human urine. To achieve this, we have comprehensively validated a method using salting-out assisted liquid/liquid extraction (SALLE) coupled to UPLC-MS/MS and isotope dilution quantification, to measure unconjugated BPA and ClxBPA in human urine according to the accepted guidelines. Deutered BPA as well as deutered 2,2'-DCBPA was used as internal standards. The matrix calibration curve ranged from 0.05 to 1.60 ng mL(-1) and from 0.5 to 16.0 ng mL(-1) for ClxBPA and BPA respectively, and provided good linearity (r(2) > 0.99). This method was precise (the intra- and inter-day coefficients of variation were < 20% at three different concentrations: 0.05 ng mL(-1), 0.2 ng mL(-1), 0.8 ng mL(-1) and 0.5 ng mL(-1), 2 ng mL(-1), 8 ng mL(-1) for ClxBPA and BPA, respectively) and accurate (bias ranged from -13% to +12%). The limit of quantification, validated at 0.05 ng mL(-1) and 0.5 ng mL(-1) for ClxBPA and BPA respectively when using 300 mu L of urine, was found to be suitable for the concentration existing in real samples. The matrix effect and the BPA cross-contamination were also investigated in this study. The analytical method developed in this study is in accordance with the requirements applicable to biomonitoring of BPA and ClxBPA in human urin

A nano-particle synthesis technology dedicated to solar cells applications

Silver nanoparticles have been prepared using a "terminated gas condensation" technique. An unprecedented control of 5-6 nm-size nanoparticles with well defined shape and variable surface densities has been achieved. The technology is shown to permit independent control of both, plasmon resonance intensity and frequency position. On the basis of optical measurements, a smart tuning of plasmon resonance intensity with particle density is indeed demonstrated. Moreover, the embedding of NPs in different surrounding medium enables to control the resonance wavelength as experimentally demonstrated and theoretically confirmed. © (2011) Trans Tech Publications, Switzerland

Pressure-induced americium valence fluctuations revealed by electrical resistivity

Electrical resistivity of americium-plutonium fcc alloys was studied over a series of high-pressure$\hbox{--}$induced structural phase transitions accompanied by a volume collapse. The temperature dependence of resistivity flattens progressively in the high-pressure phases pointing to the presence of random strong scatterers at the Fermi energy. A theoretical analysis shows that this development is not related to the expected simple delocalization of Am $5f$ states. Instead it points to pressure-induced americium valence fluctuations ($5f^{6}$-$5f^{7}$), which provides a new microscopic basis for the understanding of transuranium materials on the verge of localization of the $5f$ electronic states

Pressure-induced Americium Valence Fluctuations Revealed by Electrical Resistivity

Electrical resistivity of americium-plutonium fcc alloys was studied over a series of high-pressure¿induced structural phase transitions accompanied by a volume collapse. The temperature dependence of resistivity flattens progressively in the high-pressure phases pointing to the presence of random strong scatterers at the Fermi energy. A theoretical analysis shows that this development is not related to the expected simple delocalization of Am 5f states. Instead it points to pressure-induced americium valence fluctuations (5f6-5f7), which provides a new microscopic basis for the understanding of transuranium materials on the verge of localization of the 5f electronic states.JRC.E.6-Actinides researc