Reproducible mini-slump test procedure for measuring the yield stress of cementitious pastes

The mini-slump test is a fast, inexpensive and widely adopted method for evaluating the workability of fresh cementitious pastes. However, this method lacks a standardised procedure for its experimental implementation, which is crucial to guarantee reproducibility and reliability of the test results. This study investigates and proposes a guideline procedure for mini-slump testing, focusing on the influence of key experimental (mixing and testing) parameters on the statistical performance of the results. The importance of preparation of always testing at the same time after mixing, testing each batch once rather than conducting multiple tests on a single batch of material, is highlighted. A set of alkali-activated fly ash-slag pastes, spanning from 1 to 75 Pa yield stresses, were used to validate the test method, by comparison of calculated yield stresses with the results obtained using a conventional vane viscometer. The proposed experimental procedure for mini-slump testing produces highly reproducible results, and the yield stress calculated from mini-slump values correlate very well with those measured by viscometer, in the case of fresh paste of pure shear flow. Mini-slump testing is a reliable method that can be utilised for the assessment of workability of cements

The Electronics and Data Acquisition System of the DarkSide Dark Matter Search

It is generally inferred from astronomical measurements that Dark Matter (DM) comprises approximately 27\% of the energy-density of the universe. If DM is a subatomic particle, a possible candidate is a Weakly Interacting Massive Particle (WIMP), and the DarkSide-50 (DS) experiment is a direct search for evidence of WIMP-nuclear collisions. DS is located underground at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, and consists of three active, embedded components; an outer water veto (CTF), a liquid scintillator veto (LSV), and a liquid argon (LAr) time projection chamber (TPC). This paper describes the data acquisition and electronic systems of the DS detectors, designed to detect the residual ionization from such collisions

Time-Lapse Imaging of Astrocytes In Vivo

<p>Four astrocytes, from which fluorometric Ca²⁺ imaging (0.5 Hz) was made, are outlined. A blood vessel, outlined by the astrocyte end feet, runs diagonally across the viewed area. White arrows show the end foot connected to the imaged astrocyte.</p

In Vivo Loading and Imaging of Astrocytes Using Fluo-4 AM

<div><p>(A) Acute slice prepared 1 h after dye loading. Scale bar, 200 μm.</p> <p>(B) Higher magnification reveals cells with typical astrocyte morphology. Scale bar, 20 μm.</p> <p>(C) Average bulk fluorescence as a function of the depth from the pial surface.</p> <p>(D) Schematic drawing of the experimental arrangement. Abbreviations: EKG, electrocardiogram. PMT, photomultiplier. LFP, glass micropipe for local field potential and multiple unit recording. The same pipette was used to deliver bicuculline.</p> <p>(E) Image taken 50–150 μm below pial surface in vivo. Flattened xyz stack.</p> <p>(F) Fluo-4 AM loaded cells (left) were stained for S100B immunoreactivity (right), and the images were merged (center). See <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020096#sv003" target="_blank">Video S3</a> for large-scale staining. Scale bar, 20 μm.</p></div

Spatio-Temporal Dynamics of Astrocyte Ca²⁺ Activity

<div><p>(A) Definition of nearby (less than 50 μm) and distant (greater than 50 μm) cell pairs.</p> <p>(B) Fluorescence changes in two nearby astrocytes.</p> <p>(C) Cross-correlogram of fluorescent intensity.</p> <p>(D) Mean cross-correlation of <i>ΔF/F₀</i> in all nearby (thick line) and distant (thin line) cell pairs in control condition (left) and in the presence of bicuculline (right). Note large increase of <i>ΔF/F₀</i> correlation in nearby cell pairs in the bicuculline condition (error bar: standard error of the mean).</p> <p>(E) Relationship between distance of the two cells and the magnitude of correlation at zero timelag. Note lack of a reliable relationship in the control condition (left). Note also the significant negative correlation between the distance and correlated <i>ΔF/F₀</i> changes in cell pairs in the bicuculline-treated cortex (right).</p></div

Frequency Domain Analysis of Population Dynamics of Fluorescence in Astrocytes in Control State and during Bicuculline-Induced Neuronal Hyperactivity

<p>Insets show local field potentials in a control animal and regular spiking in a bicuculline treated mouse (scale bar: 2.0 s, 500 μV). Asterisks show significant differences (<i>p</i> < 0.05) between groups at various frequencies.</p