Quantitative study of hydration of C<Subscript>3</Subscript>S and C<Subscript>2</Subscript>S by thermal analysis

This research is part of a European project (namely, CODICE project), main objective of which is modelling, at a multi-scale, the evolution of the mechanical performance of non-degraded and degraded cementitious matrices. For that, a series of experiments were planned with pure synthetic tri-calcium silicate (C₃S) and bi-calcium silicate (C₂S) (main components of the Portland cement clinker) to obtain different calcium–silicate–hydrate (C–S–H) gel structures during their hydration. The characterization of those C–S–H gels and matrices will provide experimental parameters for the validation of the multi-scale modelling scheme proposed. In this article, a quantitative method, based on thermal analyses, has been used for the determination of the chemical composition of the C–S–H gel together with the degree of hydration and quantitative evolution of all the components of the pastes. Besides, the microstructure and type of silicate tetrahedron and mean chain length (MCL) were studied by scanning electron microscopy (SEM) and ²⁹Si magic-angle-spinning (MAS) NMR, respectively. The main results showed that the chemical compositions for the C–S–H gels have a CaO/SiO₂ M ratio almost constant of 1.7 for both C₃S and C₂S compounds. Small differences were found in the gel water content: the H₂O/SiO₂ M ratio ranged from 2.9 ± 0.2 to 2.6 ± 0.2 for the C₃S (decrease) and from 2.4 ± 0.2 to 3.2 ± 0.2 for the C₂S (increase). The MCL values of the C–S–H gels, determined from ²⁹Si MAS NMR, were 3.5 and 4 silicate tetrahedron, for the hydrated C₃S and C₂S, respectively, remaining almost constant at all hydration periods.     

Incomplete equilibrium in long-range interacting systems

We use Hamiltonian dynamics to discuss the statistical mechanics of long-lasting quasistationary states particularly relevant for long-range interacting systems. Despite the presence of an anomalous single-particle velocity distribution, we find that the central limit theorem implies the Boltzmann expression in Gibbs' Gamma space. We identify the nonequilibrium submanifold of Gamma space characterizing the anomalous behavior and show that by restricting the Boltzmann-Gibbs approach to this submanifold we obtain the statistical mechanics of the quasistationary states.     

Experimental analysis of the precessing vortex core in a free swirling jet

An experimental analysis of the precessing vortex core (PVC) instability in a free swirling jet of air at ambient pressure and temperature is performed by means of laser Doppler velocimetry (LDV) and particle image velocimetry (PIV). Two parametric studies are considered, varying the swirl parameter and the Reynolds number. The range of parameters considered allowed to study conditions of strong precession as well as the inception and settlement of the instability. Mean velocity and standard deviation profiles, power spectral density functions and probability density functions for the axial and tangential velocity components are presented. Average as well as instantaneous PIV maps are considered in the characterization of the flowfield structure and detection of the instantaneous position of the vortex center. Joint analysis of velocity PDFs and power spectra shows that the PVC contribution to the global statistics of the velocity field can be properly separated from the contribution of the true flow turbulence, giving additional insight to the physics of the precession phenomenon. The results obtained in the explored range of conditions indicate that the true turbulence intensity is not dependent on the swirl parameter. An erratum to this article can be found at     

A hyphenated microLC-Q-TOF-MS platform for exosomal lipidomics investigations: application to RCC urinary exosomes

Urinary exosomes are released from every renal epithelial cell type facing the urinary space and therefore, they may carry molecular markers of renal dysfunction and structural injury. Here, we present a hyphenated microLC-Q-TOF-MS platform for lipidomics studies applied to investigate the urinary exosome lipid repertoire. Lipids were separated by reversed-phase chromatography using a linear gradient of formic acid 0.2% and tetrahydrofuran, in 40 min of analysis. Features (m/z with associated own retention time) were extracted by MarkerLynx(TM) (Waters) and processed, demonstrating good analytical performance in terms of repeatability and mass accuracy of the microLC Q-TOF MS platform. In particular, a stable retention time (RSD less than 4%) and relative intensity (RSD from 2.9% to 11%) were observed. Moreover, the method takes advantages by the use of a lock spray interface (Waters) that allows readjusting the m/z data after acquisition, obtaining inaccuracy below 6 ppm in measuring the m/z value of the reference compound during chromatographic run. The method was employed in a preliminary application to perform comparative analysis from healthy control subjects and renal cell carcinoma (RCC) patients, in order to possibly highlight differences in lipid composition to be exploited as potential tumor biomarker. Differential lipid composition in RCC urinary exosomes was achieved and tentatively identified by accurate mass, providing a preliminary indication of a relationship between lipid composition of urinary exosomes and RCC disease. Among the total features significantly different in RCC exosomes, the ion at m/z 502.3 was taken as an example for molecular confirmation by MS/MS fragmentation analysis.     

Hard photon next-to-leading corrections to two-fermion production in e + e − collisions above the Z 0 peak

A complete next-to-leading order calculation of the initial-state O (α) photonic corrections to hadron and lepton-pair production in e ⁺ e ^?. collisions is presented. The impact of the next-to-leading order corrections on the twofermion cross section and forward-backward asymmetry is studied in detail for several event selections, with special emphasis on hard photon effects at LEP1.5 and LEP2 energies. It is shown that for typical realistic event selections, initial-state next-to-leading order corrections in the soft approximation can be safely extrapolated to energies above the Z ⁰ peak without significant loss of precision.     

Automated nonlinear alignment of XRF spectra

An important computational operation in a set of spectra is that of aligning them to a reference spectrum. In X‐ray fluorescence, this is referred to as energy calibration and may be necessary for fitting low‐count acquisitions. It may be useful for multi‐element detector systems. Typically, this is carried out in a linear manner, and sometimes requires user feedback. Automated methods exist but are often focused on specific type of data. We propose a new automated method that is based on a nonlinear approach and is specialised for X‐ray fluorescence data. The initial application in two different multi‐element detector systems in the TwinMic beamline (Elettra – Sincrotrone Trieste) yielded promising results. Copyright © 2016 John Wiley & Sons, Ltd.     

Physical basis for the symmetries in the Friedmann–Robertson–Walker metric

Modern cosmological theory is based on the Friedmann–Robertson–Walker (FRW) metric. Often written in terms of co-moving coordinates, this well-known solution to Einstein’s equations owes its elegant and highly practical formulation to the cosmological principle and Weyl’s postulate, upon which it is founded. However, there is physics behind such symmetries, and not all of it has yet been recognized. In this paper, we derive the FRW metric coefficients from the general form of the spherically symmetric line element and demonstrate that, because the co-moving frame also happens to be in free fall, the symmetries in FRW are valid only for a medium with zero active mass. In other words, the spacetime of a perfect fluid in cosmology may be correctly written as FRW only when its equation of state is ρ+3p = 0, in terms of the total pressure p and total energy density ρ. There is now compelling observational support for this conclusion, including the Alcock–Paczy´nski test, which shows that only an FRW cosmology with zero active mass is consistent with the latest model-independent baryon acoustic oscillation data.     

"Deconvoluted fullerene" derivatives: synthesis and characterization

We have designed the synthesis of "deconvoluted fullerene" derivatives that present an ordered pattern of hexagons and pentagons in the backbone of the molecule. We not only mimicked the fullerene structure in dihedral planes, but also preserved its electron accepting behavior and enlarged its optical absorption. Moreover, very preliminary photoluminescence (PL) quenching experiments also confirmed the potentiality of these materials as acceptors in the field of organic photovoltaics (OPV)s. A brief discussion of the surface morphology, based on AFM analysis, is also presented.