Kinetics of Grain Size Reduction in Minerals Undergoing Ball Milling

This work focuses on the grain size reduction induced by ball milling in individual minerals and binary mixtures containing quartz and a softer mineral. All the investigated minerals and mineral mixtures undergo a significant monotonic grain size decrease upon mechanical processing. The rate at which the process occurs in individual minerals decreases with the hardness of the mineral phase. Hardness is shown to play a crucial role also in the case of mineral mixtures. The final grain size attainable by the softer mineral as well as the rate of the grain size reduction process depend, indeed, on the amount of quartz in the mixture. A kinetic model allows rationalizing the observed behaviour based on the intensity of mechanical stresses generated during individual impacts

DFT study of [Pt(Cl)2L] complex (L = rubeanic acid) and its derived compounds with DNA purine bases

In this study, we present a systematic computational investigation on the electronic properties of cisplatin (cis-[Pt(Cl)2(NH3)2] (CP) and complex [Pt(Cl)2L] (1) (L = rubeanic acid) employing all-electron density functional theory. In detail, we analyzed essential molecular properties such as geometrical parameters, ionization energies, electron affinity, highest occupied molecular orbital, and lowest unoccupied molecular orbital energies. Concerning CP, molecule 1 exhibited improved lipophilicity and a pronounced electrophilic property. Furthermore, to investigate and compare the DNA binding capability between CP and molecule 1, we extended the investigation to the guanine and adenine derived complexes, respectively. Complexes of molecule 1 with the adenine and guanine bases followed a similar trend of stability found for CP systems, with the highest affinity found for guanine complexes. Altogether, molecule 1 displayed promising physicochemical and druglikeness features to serve as a starting point for developing a drug-like enough that could be therapeutically useful

Test of ID carbon-carbon composite prototype tiles for the SPIDER diagnostic calorimeter

Additional heating will be provided to the thermonuclear fusion experiment ITER by injection of neutral beams from accelerated negative ions. In the SPIDER test facility, under construction at Consorzio RFX in Padova (Italy), the production of negative ions will be studied and optimised. To this purpose the STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) diagnostic will be used to characterise the SPIDER beam during short operation (several seconds) and to verify if the beam meets the ITER requirement regarding the maximum allowed beam non-uniformity (below \ub110%). The most important measurements performed by STRIKE are beam uniformity, beamlet divergence and stripping losses. The major components of STRIKE are 16 1D-CFC (Carbon matrix-Carbon Fibre reinforced Composite) tiles, observed at the rear side by a thermal camera. The requirements of the 1D CFC material include a large thermal conductivity along the tile thickness (at least 10 times larger than in the other directions); low specific heat and density; uniform parameters over the tile surface; capability to withstand localised heat loads resulting in steep temperature gradients. So 1D CFC is a very anisotropic and delicate material, not commercially available, and prototypes are being specifically realised. This contribution gives an overview of the tests performed on the CFC prototype tiles, aimed at verifying their thermal behaviour. The spatial uniformity of the parameters and the ratio between the thermal conductivities are assessed by means of a power laser at Consorzio RFX. Dedicated linear and non-linear simulations are carried out to interpret the experiments and to estimate the thermal conductivities; these simulations are described and a comparison of the experimental data with the simulation results is presented

GPCALMA: a Grid Approach to Mammographic Screening

The next generation of High Energy Physics experiments requires a GRID approach to a distributed computing system and the associated data management: the key concept is the "Virtual Organisation" (VO), a group of geographycally distributed users with a common goal and the will to share their resources. A similar approach is being applied to a group of Hospitals which joined the GPCALMA project (Grid Platform for Computer Assisted Library for MAmmography), which will allow common screening programs for early diagnosis of breast and, in the future, lung cancer. HEP techniques come into play in writing the application code, which makes use of neural networks for the image analysis and shows performances similar to radiologists in the diagnosis. GRID technologies will allow remote image analysis and interactive online diagnosis, with a relevant reduction of the delays presently associated to screening programs.Comment: 4 pages, 3 figures; to appear in the Proceedings of Frontier Detectors For Frontier Physics, 9th Pisa Meeting on Advanced Detectors, 25-31 May 2003, La Biodola, Isola d'Elba, Ital

Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI’s achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Automated detection of lung nodules in low-dose computed tomography

A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector computed-tomography (CT) images has been developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, consisting in a 3D dot-enhancement filter for nodule detection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The database used in this study consists of 17 low-dose CT scans reconstructed with thin slice thickness (~300 slices/scan). The preliminary results are shown in terms of the FROC analysis reporting a good sensitivity (85% range) for both internal and sub-pleural nodules at an acceptable level of false positive findings (1-9 FP/scan); the sensitivity value remains very high (75% range) even at 1-6 FP/scanComment: 4 pages, 2 figures: Proceedings of the Computer Assisted Radiology and Surgery, 21th International Congress and Exhibition, Berlin, Volume 2, Supplement 1, June 2007, pp 357-35

Stiffening of nanoporous gold: experiment, simulation and theory

By combining electron microscopy measurements, atomistic simulations and elastic homogenization theory, we theoretically investigate the Young's modulus of nanoporous Au structures. Based on atomistic replicas generated starting from experimental tomographic evidence, atomistic simulations reveal that nanoporous Au stiffens as ligaments become finer, reproducing experimental findings obtained by nanoindentation of dealloyed samples. We argue that such a stiffening is neither due to surface stress nor to grain boundaries. Instead, we observe a direct quantitative correlation between the density of dislocations found in the material phase of the nanoporous structures and their Young's modulus and we propose a microscopic explanation of the observed stiffening. In particular, we show that local stress and strain fields in the neighborhood of dislocation cores allow dislocations to work as reinforcing solutes