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Fast Field-Cycling Nuclear Magnetic Resonance relaxometry is a non-destructive technique to investigate molecular dynamics and structure of systems having a wide range of ap- plications such as environment, biology, and food. Besides a considerable amount of liter- ature about modeling and application of such technique in specific areas, an algorithmic approach to the related parameter identification problem is still lacking. We believe that a robust algorithmic approach will allow a unified treatment of different samples in several application areas. In this paper, we model the parameters identification problem as a con- strained L 1 -regularized non-linear least squares problem. Following the approach proposed in [ Analytical Chemistry 2021 93 (24)], the non-linear least squares term imposes data con- sistency by decomposing the acquired relaxation profiles into relaxation contributions as- sociated with 1 H −1 H and 1 H −14 N dipole-dipole interactions. The data fitting and the L 1 - based regularization terms are balanced by the so-called regularization parameter. For the parameters identification, we propose an algorithm that computes, at each iteration, both the regularization parameter and the model parameters. In particular, the regularization parameter value is updated according to a Balancing Principle and the model parameters values are obtained by solving the corresponding L 1 -regularized non-linear least squares problem by means of the non-linear Gauss-Seidel method. We analyse the convergence properties of the proposed algorithm and run extensive testing on synthetic and real data. A Matlab software, implementing the presented algorithm, is available upon request to the authors.

Tricalcium silicate C3S is the major component in all kinds of cementitious materials, such as white or grey Portland cement. A deep understanding of its hydration process will enlighten us on the formation of the hydrates structure, like CSH. The use of Fast Field Cycling (FFC) is a good way to perform analyses on such kind of materials. In particular, FFC dispersion profiles of the longitudinal relaxation rates (R1=1)) on a wide range of NMR frequencies permit to get information on the dynamics of the diffusing spins, by analysing the acquired data with a suitable spin diffusion model. In this work, the 3τ model developed at the Physics Department, University of Surrey, has been fitted to experimental dispersion curve data. The model is mainly based on three characteristic correlation time constants: the bulk and the surface diffusion times and the surface desorption time. To easily fit this model to the dispersion profiles, a MATLAB® script code called 3τM has been created. The fitting process implemented in the script is based on the non linear least squares method, which will be shortly explained before a presentation of the 3τ model theory and its associated parameters. The material used, the fitting methods and the results will be also briefly described.

L'efficacia dei trattamenti normalmente impiegati per proteggere e/o consolidare materiali lapidei può essere valutata mediante la tecnica di imaging a risonanza magnetica nucleare (MRI), che consente di studiare in modo quantitativo, non invasivo, non distruttivo, la cinetica di assorbimento capillare dell'acqua. In campioni omogenei (Pietra di Lecce) si forma un fronte piatto (con una discontinuità netta alla scala di misura) e la tecnica MRI permette di seguire la cinetica in quanto consente di misurare, in funzione del tempo, l'altezza raggiunta da tale fronte in qualunque sezione interna del campione. Vengono confrontati i risultati ottenuti sullo stesso litotipo utilizzando due diversi prodotti idrorepellenti. i risultati vengono interpretati alla luce del modello di washburn per l'assorbimento capillare, fornendo parametri utilizzabili per quantificare l'efficacia del trattamento.

A new articular syndrome characterized by unusually sharp and severe arthralgias of short duration involving a few joints without evidence of synovitis has been recently described in HIV infected patients. We here report 2 additional cases occuring in AIDS patients receiving corticosteroids.

A sequence of graded ophiolitic sandstones, 120 m thick (Sanguigna Formation), outcrops within the Messinian Evaporite Group in a limited area near Gabbro, Fine Basin, western Tuscany. The formation lies between fine-grained sediments laid down under a thin water-cover. The graded beds show, on the other hand, many features typical of proximal turbidites, such as amalgamated layers, scour-and-fill structures, clay flakes and lumps, top-truncated Bouma sequences. Grain-size analyses suggest that they were deposited from high-density turbidity flows. The petrographic composition and the grain fabric indicate that the feeding was from the northeast across the Fine Basin. From the inferred dimensions and depth of the basin, the mean slope should have been less than 1°. The turbidity currents probably originated at a river mouth during flood stages. The Sanguigna graded beds are compared with occurrences of shallow-water turbidites.

The core of the Troodos Massif consists of a major tectonitic harzburgite—dunite unit (Mt. Olympus Unit) overlain by three tectonic units which, in descending order, consist of dunites, wherlites and gabbros, respectively. Furthermore, the Mt. Olympus Unit is underlain by three other tectonic units with the same lithology as the upper ones. The thrusts show a north-to-south emplacement, probably of latest Cretaceous age. It is suggested that Troodos, Southern Turkey, Hatay and Oman ophiolites could belong to the same oceanic domain; they underwent different displacement toward the Arabian—African plate.

Magnetic resonance imaging (MRI) is a powerful technique to study capillary water absorption kinetics in sedimentary rocks. However, the noise in the images can limit the correct identification and the quantitative measurement of the average height reached by the wetting front inside the porous material where imbibition occurs. Therefore, denoising methods can be applied to improve the image quality for a more accurate analysis, without the disadvantages of longer acquisition times. This study attempts to improve the signal-to-noise ratio of the images acquired by MRI on a sedimentary rock (Pietra di Lecce) using a waveletbased thresholding technique. The idea is to average some slightly different discrete wavelet tansforms (DWT), called e-decimated DWT, to define the stationary wavelet transforms (SWT).

TOUGH2 is an integral finite differences numerical simulator for non-isothermal multiphase flow in fractured porous media, which can manage complex spatial discretizations. Numerical simulation accuracy is affected, among other things, by grid resolution. Increasing the grid resolution requires computational and operating costs depending on the number of nodes and variables processed. The complexity of the management of the model increases when unstructured grids and local refinement are used. In order to improve the management and optimize the activities to update the model, an open source pre-processor has been developed using the open source codes GRASS GIS, SQLite and AMESH. Operations such as domain discretization, rock type assignment and mesh file generation have been automatized. Graphical interfaces allow for a user-friendly utilization. Operating errors and time required by pre-processing activities to generate and update locally refined unstructured grids have been reduced. Productivity in numerical modeling has been substantially increased. A novel approach to generate TOUGH2 input file through GIS is presented.TOUGH2GIS automatically creates locally refined unstructured 3D grids.Rock types attribution to grid blocks is automatically and efficiently performed.Seamless integration into an available open-source GIS package.An application to a sample dataset shows method feasibility.

Time-Domain Nuclear Magnetic Resonance (TD-NMR) of 1 H nuclei is used to monitor the maturation up to 30 days of three different endodontic cement pastes. The “Solid–liquid” separation of the NMR signals and quasi-continuous distributions of relaxation times allow one to follow the formation of chemical compounds and the build-up of the nano- and subnano-structured C–S–H gel. 1 H populations, distinguished by their different mobilities, can be identified and assigned to water confined within the pores of the C–S–H gel, to crystallization water and Portlandite, and to hydroxyl groups. Changes of the TD-NMR parameters during hydration are in agreement with the expected effects of the different additives, which, as it is known, can substantially modify the rate of reactions and the properties of cementitious pastes. Endodontic cements are suitable systems to check the ability of this non-destructive technique to give insight into the complex hydration process of real cement pastes.

We present a novel approach to the nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) analysis of complex samples with nontrivial distribution of longitudinal relaxation rate R(1). Parametrically enabled relaxation filters with double and multiple inversion (PERFIDI) aim to separate signals arising from components with different R(1) values prior to actual data acquisition. Given any standard NMR/MRI pulse sequence, which, by itself, is insensitive to differences in R(1) values, it can be combined with a PERFIDI preamble, which functions as a preliminary R(1) filter and confers on the original technique sensitivity to the dimension R(1). This article states the principles of the approach, including the way to account for instrumental imperfections, and shows how PERFIDI with specific filter profile functions can be built. Using terms borrowed from electronics, these filters are classified as low-pass, high-pass and band-pass types. Also included are an experimental verification example and a discussion of potential applications of PERFIDI in various NMR areas.

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. H-1 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 H-1 pools, identified as H-1 nuclei in C-S-H layers, likely belonging to OH groups, with H-1 nuclei in Portlandite, and in crystal water of Ettringite. By assuming these assignments, our data allowed us to compute the distances of pairs of H-1 nuclei in Portlandite and in crystal water ((1.9 +/- 0.2) angstrom and (1.6 +/- 0.1)angstrom, 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.

TOUGH2Viewer is a Java program capable of displaying unstructured (Voronoi complying) grids, locally refined and structured grids (complying with the MESHMAKER iTOUGH2 format). In particular, TOUGH2Viewer allows to navigate through a 3D grid compatible with the iTOUGH2 data file format and see: (1) the thermodynamic variables and the material (namely, petrophysical properties) of each block; (2) maps of isovalues (2D) of all thermodynamic variables; (3) isosurfaces (3D) of all thermodynamic variables; (4) flows of mass and heat between blocks; (5) spatial profiles of thermodynamic variables, of a selected set of blocks, long a Cartesian directions; (6) time plot of thermodynamic variables of a selected block. All commands to manage a 3D visualization (zooming, pan, rotations) are CAD complying.

Within the MAC-GEO research project, funded by Regione Toscana and addressed to the exploitation of high enthalpy geothermal systems, the authors worked on the utilization and customization of the open source numerical simulator TOUGH2, as implemented in the code dedicated to model calibration iTOUGH2. TOUGH2 is one of the most used numerical simulation software for non-isothermal flow of multicomponent, multiphase fluids in one, two and three-dimensional porous and fractured media. Lacking an official Graphical User Interface tool for post-processing operations, several commercial and academic software have been developed to manage and display TOUGH2 input and output data files. Almost all of these tools seem to have limits to visualizing parameter values of the numerical model, work only with a predefined binary version of TOUGH2, and only a few of them can manage locally refined unstructured grids (i.e. Voronoi grids). To overcome these limitations, the authors have developed and tested a dedicated software application (called TOUGH2Viewer) for reading and managing TOUGH2 output files, written in Java and able to provide an interactive 3D view of the numerical model. Several functionalities have been implemented for block query and searching, contour mapping and 3D surface mapping of TOUGH2 primary variables (i.e. pressure, temperature, etc.). TOUGH2Viewer is also able to display 2D and 3D views of mass and heat flow between blocks, for each time step in which the simulation proceeds. The application described in this paper is under development to improve its functionalities; nevertheless the current software release is a valid support tool for post-processing that significantly improves the possibility to inspect the simulated data coming from TOUGH2.

Nell'ambito del progetto di ricerca MAC-GEO, finanziato dalla Regione Toscana, rivolto alla definizione di un sistema decisionale integrato, da utilizzarsi nelle procedure di controllo di concessioni per lo sfruttamento di sistemi geotermici ad alta entalpia, gli autori hanno personalizzato e utilizzato il simulatore numerico open source TOUGH2, specificatamente nella versione implementata nel codice dedicato alla calibrazione di modelli iTOUGH2. TOUGH2, sviluppato a partire dagli anni ottanta, è il simulatore per bacini geotermici, ma non solo, di gran lunga più diffuso a scala internazionale; è molto robusto e, grazie alla sua struttura modulare, è molto flessibile. Permette di studiare flussi di fluidi non isotermi, multicomponente e multifase in mezzi porosi continui o fratturati con domini 1D, 2D e 3D e, grazie al metodo di discretizzazione alle Differenze Finite Integrali (IFDM), può anche gestire griglie raffittite con blocchi a geometria irregolare. È scritto in linguaggio Fortran e pertanto può essere facilmente utilizzato sotto diversi sistemi operativi. Nel presente lavoro si farà implicitamente riferimento alla versione realizzata in ambiente Linux. La discretizzazione del serbatoio geotermico con un elevato numero di blocchi migliora notevolmente l'accuratezza del risultato di una simulazione, ma può rappresentare un limite nei processi di history matching e nelle analisi di sensibilità, a causa dell'elevata quantità di dati da gestire. Con script bash realizzati ad hoc, da lanciare in ambiente GRASS GIS ed utilizzando il modulo “v.trimesh”, è possibile generare griglie vettoriali irregolari 3D che rispettano le condizioni geometriche imposte dal metodo IFDM proprio di TOUGH2 e popolare automaticamente un modello numerico con parametri appropriati. Facendo ricorso a mappe raster di elevazione, rappresentative del modello geologico concettuale, si associa automaticamente ad ogni blocco della griglia il materiale che si considera più rappresentativo della realtà. L'insieme di dati strutturati così ottenuto è quindi elaborato con una versione modificata ad hoc di AMESH (un codice FOS distribuito dal Lawrence Berkeley National Laboratory) per ottenere il file di input geometrico di TOUGH2. Infine, un software di visualizzazione (scritto in Java), ulteriore prodotto del gruppo di ricercatori, permette di analizzare i risultati della simulazione più speditamente. L'applicazione di tali strumenti sui grandi bacini geotermici ad alta entalpia della Toscana, ha dimostrato come essi consentano di ridurre sensibilmente i tempi di pre / post – processing nella simulazione full field, specificatamente nelle simulazioni, sia dirette che inverse, di sistemi che necessitino di raffittimenti irregolari.

Editorial del Volume contenente una selezione di contributi presentati al "10th International Bologna Conference Magnetic Resonance in Porous Media" (MRPM 10) September 2010, Leipzig, Germany, www.diffusion-fundamentals.org

Time-domain nuclear magnetic resonance (TD-NMR) of (1)H nuclei has been used to monitor and model changes of endodontic cement pastes during hydration, from the initial reaction period up to hours and days. The (1)H in the samples are divided into two major spin groups by fitting each free induction decay, acquired after the second pulse of an inversion recovery (I-R) pulse sequence with variable interpulse delay, by the sum of a quasi-Gaussian (signal from low mobility nuclei) and an exponential (from higher mobility nuclei). The extrapolations to zero time of the signals from the two spin groups give two sets of I-R data that have been analyzed to give quasi-continuous T(1) distributions. After about a day, two clearly solid components appear. From a day to a few days, three liquid populations are identified, one of them mainly in the low-mobility spin group, which later merge, giving a single T(1) or T(2) peak. The rapid onset of the solid components, at the cost of the liquid, and the rapid changes of the relaxation time distributions of all components are clear indicators of the amount and kinetics of reaction products formation (C-S-H gel and Portlandite) and of the C-S-H micronanoporous structure buildup and evolution. At 30 days of hydration, the very short T(1) and T(2) liquid component (T(1) congruent with 200 micros and T(2) congruent with 50 micros) can be assigned to C-S-H intralayer water (thickness of the order of fractions of a nanometer) and the remaining liquid signal to interlayer water (thickness of the order of 1 nm). Comparisons are made among a widely used commercial endodontic cement paste and two more recent commercial pastes, with additive compounds to make the hydration process faster and to increase the workability. Parameters can be extracted from the data to characterize the different kinetics and nanostructure of the pore space formed up to 30 days. The parameters are in agreement with the expected effects of the additives, so the parameters can be used to optimize the formulation of new pastes, in order to improve their therapeutic performance.

The paper is addressed to help designing alkali/surfactant flooding Enhanced Oil Recovery methods. In particular, it has been verified that a polar interaction mechanism to change wettability of a carbonate rock from water-wet to oil-wet can be obtained by injecting adequate chemicals, and in particular a solution of oleic acid and non-polar oil, like dodecane used for laboratory experiments. It is worth recalling that wettability is a petrophysical property that directly affects oil recovery by controlling the location, flow and distribution of fluids inside the reservoir rock. The study has been performed by combining spatially resolved and spatially non-resolved 1H-NMR (Nuclear Magnetic Resonance) information obtained on full-size cores (up to 7cm in diameter). In particular, spatially resolved quantitative NMR imaging maps (or Quantitative Relaxation Tomography, QRT) and spatially-non resolved (or Magnetic Resonance Relaxometry, MRR) analyses have been performed on full-size cores to track the process and to assess the quality of wettability reversal. Changes of relaxation time distributions and of T1 maps obtained in the experiments seem correlated with wettability changes measured after the chemical treatment, i.e., the contamination with a solution of oleic acid and dodecane. Although further investigations are needed, the combination of MRR and QRT seems a promising technique to correlate the traditional Amott wettability index with local values of T1 in internal sections of a rock sample. In particular, the paper deals with the assessment and monitoring of wettability reversal of carbonate rocks used in laboratory studies to evaluate the efficiency of chemical Enhanced Oil Recovery methods, and in particular of alkali/surfactant flooding. The combination of 1H-NMR relaxation analysis, characterized by high temporal resolution, with quantitative maps, characterized by high spatial resolution, permits a better knowledge and the monitoring of the processes occurring inside the pore space leading to wettability reversal.