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[en] Pore-scale models represent an appealing approach for obtaining a more accurate and mechanistic description of physical and chemical processes in heterogeneous porous media such as cement-based materials. For this purpose, a coupled code, which is able to calculate reactive transport processes in porous media on the pore scale using the Lattice-Boltzmann approach, is developed. The aim of this coupled code is to simulate chemicallydriven alteration and degradation processes and solute transport in cement-based materials. Geometrical changes of the pore structure due to dissolution and precipitation processes at the microscopic scale can have significant effects on the macroscopic hydrodynamic properties of porous media. In this context, the current development status and the techniques used to simulate precipitation processes on the pore-scale in a realistic way are outlined. A model consisting of a gypsum containing pore leading to ettringite precipitation on monosulfoaluminate is depicted to illustrate the effect of the recent development iteration.
[en] This study is a prior step towards the modelling of real interactions between hydrated OPC and groundwater from Josef Underground Facility (GW Josef) with or without addition of Czech bentonite under in-situ conditions (10°C) and by heating (95°C) performed in cooperation with Czech laboratories (UJV and CTU-CEG) as a part of WP1. In this contribution, bentonite dissolution and formation of new phases in model cement-leach aqueous solution has been studied by geochemical calculations in PhreeqC. Compositions of the Czech commercial Bentonite 75 (denoted as B75) and the hydrated OPC (CEM II A-S 42.5R) taken into consideration by modelling were based on experimental XDR analyses. The lack of OPC in identified phases (no S-phases, no amorphous Na/K-compounds, no quantitative information) led to a simplification of modelled systems. In the systems without bentonite (hydrated OPC contacted with GW Josef) initial concentration of dominant cations Na/K-species has been raised, with the aim to adjust ionic strength and pH, respecting real analysis of cement leachates in liquid phases performed for nine months of interaction. To improve this model, further XRF analysis of hydrated OPC is needed, as the prediction of the C/S ratio is necessary. Influences of phase ratio m : m : m and temperature on dissolution, forming phases or composition of pore water were studied. Despite the simplification of the model, the results (e.g., formation of C-A-S-H and phases based on CaCO) on the boundary of cement and bentonite are in an agreement with experiments.
[en] Cementitious materials behaviour must be predictable through the lifetime of nuclear waste repository to ensure the functionality of the engineered barrier system. Thermodynamic modelling is a useful tool to predict the behaviour of the cementitious materials in extremely long time span. Together with the experimental results, modelling provides potential scenarios of cementitious materials behaviour during the lifetime of the repository. Largest uncertainties that are related to the thermodynamic modelling of the cementitious materials are related to calcium-silicate-hydrates, the main reaction product of cementitious materials. The goal of the current study was to define modelling parameters for calcium-silicate-hydrates that are credible and transparent. Ion activity product and Gibbs formation energies were calculated from various solution compositions. Calculated results enable determination of solubility products and formation energies with varying silicate chain lengths and CaO/SiO-ratios. Dimeric silicate chain lengths were arbitrarily selected for further modelling. Calcium-silicate-hydrates were modelled as a solid solution and the results were compared to the experimentally measured pH, calcium and silicon concentrations. Modelled results were in good agreement with the measured results. In the future, leaching of calcium-silicate-hydrates will be modelled and compared with the experimental results. Silicate chain length and solid solution end-members effects on the modelling will be further investigated.
[en] This book first discusses the role hydrogen can have in energy transition. For this purpose, it proposes an overview of its present economy, markets and actors, of its possible role in economy decarbonization, and of the role of electrolytic hydrogen in public policies. Then, it presents and comments the different systems of production of de-carbonated hydrogen by using water and electricity (thermolysis, photo-catalysis, electrolysis), by using biomass (pyrolysis and gasification, biogas reforming, thermochemical process, biological processes), or by using hydrocarbons with CO2 capture and storage. It addresses the various aspects related to hydrogen packing: safety (standards, regulations), storage (technologies) and distribution (by ducts, road or rail transport, ship transport). After a comparison of the different production processes in terms of energy consumption, CO2 emissions, and costs, the different actual or possible usages of hydrogen are overviewed: for industry, transport and building decarbonization, for electric power production
[en] The ITER Ion Cyclotron Heating and Current Drive system (IC H-CD) is designed to deliver 20 MW to a broad range of plasma scenarios between 40 and 55 MHz, during very long pulses. It consists of two broadband equatorial port plug antennas, their pre-matching and matching systems, transmission lines, Radio Frequency (RF) Sources and High Voltage Power Supplies. The overall project schedule has been revised and agreed by ITER Council; it re-integrates the second antenna and its power supplies in construction baseline and sets the dates for progressive installation with DT phase planned in 2035. Recent progress on ICRF subsystems is reported, covering design evolution, qualification of test articles and specific results in domestic agencies, suppliers, associated laboratories and ITER organisation. (authors)
[en] X-ray tomography has entered the industrial world. The last Nikon XTH450 machine acquired by Sematec Metrology can control the sizes of metal pieces up to a diameter of 400 mm and a length of 600 mm. The accuracy is in the 10, 20 μm range and the spatial resolution reaches 30 at 400 μm. This X-ray digital tomograph will allow Sematec Metrology to work on any metal parts made of steel, silver, lead, gold... up to a thickness of several centimeters. (A.C.)
[en] At Cadarache (southern France) the ITER consortium (International Thermonuclear Experimental Reactor) is building piece by piece what could become the very first prototype of tomorrow's power plant. The principle of ITER tokamak is the fusion of hydrogen atoms. This process, common in all stars of the universe, raises considerable scientific and technological challenges to be reproduced on the Earth's ground. If the first tests of ITER are favourable, this prototype will open up the way to the first fusion reactors by 2025, a decisive step towards abundant and clean energy
[en] Computed tomography (CT) use is increasing in the emergency department (ED). Many physicians are concerned about exposing patients to radiation from CT scanning, but estimates of radiation doses vary. This study’s objective was to determine the radiation doses from CT scanning for common indications in a Canadian ED using modern multidetector CT scanners. Methods: We conducted a health records review of consecutive adult patients seen at two busy tertiary care EDs over a 2-month period who underwent CT scanning ordered by emergency physicians. Cases were identified by searching an imaging database. Data collected included patient age and sex, study indication, scanner model, body area, and reported dose-length product. Effective dose per scan was calculated from reported dose-length product. Data were collected on a standardized form, entered into an electronic database, and analyzed with descriptive statistics and 95% CIs. Results: During the study period, emergency physicians assessed 19,880 patients. Overall, 2,720 (13.7%) underwent CT scanning, and of these, 144 (5.3%) patients had more than one scan. Patients had a mean age of 59.0 years, and 45.3% were men. Mean doses for the most common indications were as follows: simple head, 2.9 mSv; cervical spine, 5.7 mSv; complex head, 9.3 mSv; CT pulmonary angiogram, 11.2 mSv; abdomen (nontraumatic abdominal pain), 15.4 mSv; and abdomen (renal colic), 9.8 mSv. Conclusions: Approximately one in seven ED patients had a CT scan. Emergency physicians should be aware of typical radiation doses for the studies they order and how the dose varies by protocol and indication. (author)
[en] AIMS: We performed a review of the clinical, mammographic and sonographic findings of fat necrosis in a group of patients who presented with a lump in the breast. We aimed to show that, in the light of a non-specific combination of findings, an ultrasound-guided core-biopsy (CB) is a safe, quick and useful test to confirm the diagnosis. The procedure makes it possible to reassure the patient of the true identity of the lesion, thus avoiding the need for surgical excision or follow-up investigations. MATERIALS AND METHODS: We undertook a retrospective review of the clinical presentation, imaging findings and subsequent management of 23 histologically proven cases of fat necrosis. All patients had presented to a specialist breast clinic with a breast lump. RESULTS: Only 52% of patients had a definite history of trauma. Clinical examination intimated that the lump was possibly malignant in 22%, while 4.5% were probably malignant. Fifty-seven per cent of mammograms were completely normal, however ultrasound showed an abnormality in 100%. Of these 100%, 74% were interpreted as possibly malignant. The diagnosis of fat necrosis was histologically confirmed by ultrasound-guided needle core biopsy, performed at the time of initial presentation. All patients were subsequently discharged. The mean time interval from investigation and biopsy to final diagnosis and discharge of the patient was 5.9 days. CONCLUSION: We show that fat necrosis often has a confusing clinical presentation. Imaging by either mammography or ultrasound is often inconclusive and ultrasound-guided core biopsy will confirm the diagnosis sparing patients unnecessary radiological follow-up or surgical excision.R. L. Harrison (2000). Clinical Radiology55, 119–123.
[en] AIMS: To determine if the number of flecks of calcification retrieved at stereotaxic core needle biopsy or the number of core samples obtained containing calcification are related to biopsy sensitivity, and to determine how many calcifications or cores containing calcification the radiologist should aim to retrieve when sampling mammographic microcalcification. MATERIALS AND METHODS: A retrospective review was performed of core specimen radiographs from 57 consecutive patients who had stereotaxic core needle biopsies of impalpable malignant microcalcifications without an associated mammographic mass. The total number of calcifications retrieved and the numbers of cores containing calcification were correlated with findings at core and surgical histology. RESULTS: Increasing retrieval of calcification elements visible on specimen radiography was associated with increasing sensitivity of the biopsy. Five or more flecks of calcium gave an absolute sensitivity of 100%. Increasing numbers of core samples obtained containing radiographically demonstrable calcification was also associated with increasing sensitivity. Three or more cores containing calcium resulted in a 100% absolute sensitivity for malignancy. CONCLUSION: To ensure adequate sampling of calcification at core biopsy, an optimum of either three or more cores containing calcium or five or more flecks of calcium in total is required. Achieving this target ensures a high pre-operative diagnosis rate for malignant microcalcifications.Bagnall, M. J. C. (2000). Clinical Radiology55, 548–553.