Bortolotti V.,DICAM |
Brizi L.,University of Bologna |
Brizi L.,Centro Enrico Fermi |
Brown R.J.S.,953 West Bonita Avenue |
And 4 more authors.
Langmuir | Year: 2014
Cement hydration occurs when water is added to cement powder, leading to the formation of crystalline products like Portlandite and the quasi-amorphous, poorly crystalline, calcium silicate hydrate (C-S-H) gel. Despite its importance in determining the final properties of the cement, many models exist for the nano and sub-nano level organization of this "liquid stone." 1H NMR relaxometry in White Portland Cement paste during hydration allowed us to monitor the formation and evolution of the multiscale porosity of the cement, with the formation of structures at nano and sub-nano levels of C-S-H gel (calcium silicate interlayer water, water in small and large gel pores) along with three low-mobility 1H pools, identified as 1H nuclei in C-S-H layers, likely belonging to OH groups, with H nuclei in Portlandite, and in crystal water of Ettringite. By assuming these assignments, our data allowed us to compute the distances of pairs of 1H nuclei in Portlandite and in crystal water ((1.9 ± 0.2) Å and (1.6 ± 0.1) Å, respectively), consistent with the known values of these distances. The picture of the porous structure at nano and sub-nano levels emerging from our results is consistent with the Jennings colloidal model for C-S-H gel. Moreover, the constant values observed during hydration of parameters extracted from our data analysis strongly support that model, being compatible with the picture of C-S-H gel developing in comparable-sized clumps of the same composition, but not easily interpretable by models proposing quasi continuous sheets of C-S-H layers. © 2014 American Chemical Society.
Agafonova N.Yu.,RAS Institute for Nuclear Research |
Aglietta M.,National Institute of Nuclear Physics, Italy |
Antonioli P.,National Institute of Nuclear Physics, Italy |
Ashikhmin V.V.,RAS Institute for Nuclear Research |
And 38 more authors.
Physical Review Letters | Year: 2012
We report the measurement of the time of flight of ∼17GeV ν μ on the CNGS baseline (732 km) with the Large Volume Detector (LVD) at the Gran Sasso Laboratory. The CERN-SPS accelerator has been operated from May 10th to May 24th 2012, with a tightly bunched-beam structure to allow the velocity of neutrinos to be accurately measured on an event-by-event basis. LVD has detected 48 neutrino events, associated with the beam, with a high absolute time accuracy. These events allow us to establish the following limit on the difference between the neutrino speed and the light velocity: -3.8×10 -6<(v ν-c)/c<3.1×10 -6 (at 99% C.L.). This value is an order of magnitude lower than previous direct measurements. © 2012 American Physical Society.
Labini F.S.,Centro Enrico Fermi |
Labini F.S.,CNR Institute for Complex Systems
Classical and Quantum Gravity | Year: 2011
Standard models of galaxy formation predict that matter distribution is statistically homogeneous and isotropic and characterized by (i) spatial homogeneity for r < 10 Mpc h-1, (ii) small-amplitude structures of relatively limited size (i.e. r < 100) Mpc h-1 and (iii) anti-correlations for r > rc ≈ 150 Mpc h-1 (i.e. no structures of size larger than rc). Whether or not the observed galaxy distribution is interpreted to be compatible with these predictions depends on the a priori assumptions encoded in the statistical methods employed to characterize the data and on the a posteriori hypotheses made to interpret the results. We present strategies to test the most common assumptions and we find evidence that, in the available samples, galaxy distribution is spatially inhomogeneous for r < 100 Mpc h-1 but statistically homogeneous and isotropic. We conclude that the observed inhomogeneities pose a fundamental challenge to the standard picture of cosmology but they also represent an important opportunity which may open new directions for many cosmological puzzles. © 2011 IOP Publishing Ltd.
Goffredo S.,University of Bologna |
Prada F.,University of Bologna |
Caroselli E.,University of Bologna |
Capaccioni B.,University of Bologna |
And 10 more authors.
Nature Climate Change | Year: 2014
Anthropogenic CO2 is a major driver of present environmental change in most ecosystems1, and the related ocean acidification is threatening marine biota2. With increasing pCO2, calcification rates of several species decrease3, although cases of upregulation are observed4. Here, we show that biological control over mineralization relates to species abundance along a natural pH gradient. As pCO2 increased, the mineralogy of a scleractinian coral (Balanophyllia europaea) and a mollusc (Vermetus triqueter) did not change. In contrast, two calcifying algae (Padina pavonica and Acetabularia acetabulum) reduced and changed mineralization with increasing pCO2, from aragonite to the less soluble calcium sulphates and whewellite, respectively. As pCO2 increased, the coral and mollusc abundance was severely reduced, with both species disappearing at pH < 7.8. Conversely, the two calcifying and a non-calcifying algae (Lobophora variegata) showed less severe or no reductions with increasing pCO2, and were all found at the lowest pH site. The mineralization response to decreasing pH suggests a link with the degree of control over the biomineralization process by the organism, as only species with lower control managed to thrive in the lowest pH. © 2014 Macmillan Publishers Limited. All rights reserved.
Bortolotti V.,University of Bologna |
Brown R.J.S.,953 W. Bonita Ave. |
Fantazzini P.,University of Bologna |
Fantazzini P.,Centro Enrico Fermi |
And 2 more authors.
Microporous and Mesoporous Materials | Year: 2013
The kinetics of cement hydration has been studied by 1H-NMR, through the analysis of the Free Induction Decay (FID) combined with quasi-continuous T1 relaxation time distributions analysis, operating a sort of 2D T1-T2 correlation analysis on a somewhat more physical than mathematical basis. The analysis allowed us to distinguish two solid components, SS (Solid-Short) with T1 of a few milliseconds and SL (Solid-Long) with T1 of the order of a second, ascribable to 1H of anisotropically bound groups in the C-S-H gel, and to 1H nuclei of the Portlandite crystals and possibly to crystal water in Ettringite crystals, respectively. A liquid-like component LS (Liquid-Short) with very short T2 (∼80 μs) and T1 a few milliseconds, both quite stable during hydration, was isolated and interpreted as water confined in the interlayer spaces of the gel. Amounts of LS and SS increase together steadily during hydration, and these, divided by LL (Liquid-Long, the signal from the water in the pores), are proportional to 1/T1 for LL, confirming a surface relaxation effect for LL. © 2013 Elsevier Inc. All rights reserved.
Camaiti M.,CNR Institute of Neuroscience |
Camaiti M.,Centro Enrico Fermi |
Bortolottic V.,University of Bologna |
Fantazzini P.,Centro Enrico Fermi |
Fantazzini P.,University of Bologna
Magnetic Resonance in Chemistry | Year: 2015
Scientists applying magnetic resonance techniques to cultural heritage are now a quite vast and international community, even if these applications are not yet well known outside this community. Not only laboratory experiments but also measurements in the field are now possible, with the use of portable nuclear magnetic resonance (NMR) instruments that enable non-invasive and non-destructive studies on items of any size, of high artistic and historical value as well as diagnosis of their conservation state. The situation was completely different in the second half of the 1990s when our group started working on applications of NMR to cultural heritage, by combining the knowledge of NMR for fluids in porous media at the University of Bologna, with the skilfulness of the chemists for cultural heritage of CNR and University of Florence, and Safeguarding Cultural Heritage Department of Aosta. Since then, our interest has been mainly devoted to develop methods to study the structure of pore space and their changes as a result of the decay, as well as to evaluate performance of the protective and conservative treatments of porous materials like stone, ceramic, cements and wood. In this paper, we will review the pathway that led us from the first tentative experiments, in the second half of the 1990s to the current work on these topics. Copyright © 2014 John Wiley & Sons, Ltd.
Fritzsch P.,University of Southampton |
Fritzsch P.,University of Munster |
Heitger J.,University of Munster |
Tantalo N.,University of Rome Tor Vergata |
Tantalo N.,Centro Enrico Fermi
Journal of High Energy Physics | Year: 2010
We non-perturbatively determine the renormalization constant and the improvement coefficients relating the renormalized current and subtracted quark mass of (quenched) valence quarks propagating in a sea of O(a) improved two massless quarks. We employ the Schrödinger functional scheme and fix the physical extent of the box by working at a constant value of the renormalized coupling. Our calculation yields results which cover two regions of bare parameter space. One is the weak-coupling region suitable for volumes of about half a fermi. By making simulations in this region, quarks as heavy as the bottom can be propagated with the full relativistic QCD action and renormalization problems in HQET can be solved non-perturbatively by a matching to QCD infinite volume. The other region refers to the common parameter range in large-volume simulations of two-flavour lattice QCD, where our results have particular relevance for charm physics applications. © 2010 SISSA, Trieste, Italy.
de Divitiis G.M.,University of Rome Tor Vergata |
Petronzio R.,University of Rome Tor Vergata |
Tantalo N.,University of Rome Tor Vergata |
Tantalo N.,Centro Enrico Fermi
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010
We propose a preconditioning of the Dirac operator based on the factorisation of a predefined function related to the decay of the propagator with the distance. We show that it can improve the accuracy of correlators involving heavy quarks at large distances and accelerate the computation of light quark propagators. © 2010 Elsevier B.V.
Murtas G.,Centro Enrico Fermi
Systems and Synthetic Biology | Year: 2010
One of the major properties of the semi-synthetic minimal cell, as a model for early living cells, is the ability to self-reproduce itself, and the reproduction of the boundary layer or vesicle compartment is part of this process. A minimal bio-molecular mechanism based on the activity of one single enzyme, the FAS-B (Fatty Acid Synthase) Type I enzyme from Brevibacterium ammoniagenes, is encapsulated in 1-palmitoyl-2oleoyl-sn-glycero-3-phosphatidylcholine (POPC) liposomes to control lipid synthesis. Consequently molecules of palmitic acid released from the FAS catalysis, within the internal lumen, move toward the membrane compartment and become incorporated into the phospholipid bilayer. As a result the vesicle membranes change in lipid composition and liposome growth can be monitored. Here we report the first experiments showing vesicles growth by catalysis of one enzyme only that produces cell boundary from within. This is the prototype of the simplest autopoietic minimal cell. © 2009 The Author(s).
PubMed | Centro Enrico Fermi
Type: Journal Article | Journal: Systems and synthetic biology | Year: 2012
One of the major properties of the semi-synthetic minimal cell, as a model for early living cells, is the ability to self-reproduce itself, and the reproduction of the boundary layer or vesicle compartment is part of this process. A minimal bio-molecular mechanism based on the activity of one single enzyme, the FAS-B (Fatty Acid Synthase) Type I enzyme from Brevibacterium ammoniagenes, is encapsulated in 1-palmitoyl-2oleoyl-sn-glycero-3-phosphatidylcholine (POPC) liposomes to control lipid synthesis. Consequently molecules of palmitic acid released from the FAS catalysis, within the internal lumen, move toward the membrane compartment and become incorporated into the phospholipid bilayer. As a result the vesicle membranes change in lipid composition and liposome growth can be monitored. Here we report the first experiments showing vesicles growth by catalysis of one enzyme only that produces cell boundary from within. This is the prototype of the simplest autopoietic minimal cell.