bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of scenario analysis and database for quantitative analysis of microbial effects on the repository performance
Authors: Yoshikawa Hideki , Inagaki Manabu , Miyasaka Iku 
Published: April 2011

AbstractA scenario analysis was performed for microbial effect on the performance assessment (PA) of the high-level radioactive waste disposal system. Based on review of recent literature on PA and some results of our experiment, possible scenario of microbial effects on the Japanese high-level radioactive waste disposal system were analyzed. The result of the analysis shows that the microbial effect on groundwater evolution, which is caused by the microbial redox reaction, is one of the most important issues in assessing PA. The evolution not only affects radionuclide migration but also the life-time of metal overpack corrosion.To assess the microbial effect on groundwater evolution, a numerical estimation code is required, with reliable parameters for analysis of microbial activities used in the code. A biological parameter database has been developed to give the growth and metabolism of the six typical microbial groups to be used in the estimation code. For this purpose, about 573 data from 95 papers were examined to obtain effective data for disposal. The database is composed of significant data like specific growth rate, maximum growth rate, constant decay rate, and experimental condition for model assessment.
Effect of Calcium Silicate Hydrate Precipitates at Cementitious and Bentonite Material Interface on Long-Term Engineered Barrier System Performance in TRU Waste Disposal Facilities
Authors: Kurosawa Susumu , Sakamoto Hiroyuki , Nitta Kiyofumi , Numako Chiya , Haga Kazuko , Shibata Masahito , Sato Tsutomu , Nakazawa Toshiyuki , Owada Hitoshi 
Published: April 2011

AbstractChemical conditions and mass transport properties of engineered barrier systems in TRU waste facilities would change with time due to the interaction of cement/bentonite materials. (‘TRU waste’ is one of categories of the radioactive wastes and contains a significant amount of alpha-emitting transuranic nuclides. In some countries, these wastes are classified into the Intermediate Level Waste (ILW).) Previous numerical model analyses to assess the long-term performance of engineered barrier systems in TRU waste repositories predicted to form Calcium Silicate Hydrate (C-S-H) species at the interface between the cementitious and bentonite materials. If C-S-H precipitates in the bentonite side of the boundary, mass transport in the bentonite buffer decreases and mineralogical alterations are expected to be restricted for a long period. The evidence of C-S-H precipitation in the bentonite side, however, still has not been identified in the former experimental studies. To improve the reliability of numerical analyses, immersion experiments were performed using contact samples of cementitious and bentonite materials, and X-ray absorption fine structure (XAFS) analysis was carried out to detect C-S-H precipitation at the contacting interface. Precipitation of C-S-H was confirmed from the obtained XAFS spectra. This result is one of the evidences to show the validity of the current numerical model analyses, which suggests that the bentonite buffer performance as an engineered barrier would be kept over a long period.
Leaching of Bituminized Waste Products (BWP) by Pure Water: The Contribution of NMR Techniques for the Investigation of the Porous Layer
Authors: Le Feunteun S. , Diat O. , Guillermo A. , Ledieu A. , Poulesquen A. 
Published: April 2011

AbstractThe aim of this study is to improve the understanding of the water infiltration within Bituminized Waste Products (BWP) and the associated phenomena such as the development of the porous layer, the matrix swelling or the water uptake kinetics. Two sets of leaching experiments have been performed on synthesized model samples that are constituted by inactive soluble and/or insoluble salts (40% wt) embedded in bitumen. Large samples were used to quantify the water uptake kinetics and to control the macroscopic swelling of the matrixes during experiments. Smaller samples were used to characterize the depth distribution of the infiltrated water and its motion properties by NMR techniques (1H-T1 relaxation times and 1D-NMR imaging). These techniques enabled us to study the influence of the matrix chemical composition on the water advance in depth as a function of the leaching time. Results show that insoluble salts have a significant influence on water transport while soluble salts entail the development of large porosities. Preliminary results obtained with an original method based on the measurement of NMR relaxation times along the water concentration in depth are presented. They illustrate the great potential of the approach to further improve our knowledge on the establishment of the aqueous network.
Study of the Processes Related to the Water Uptake of Eurobitum Bituminized Radioactive Waste: Effect of Salt Concentration
Authors: Mariën An , Smets Steven , Valcke Elie 
Published: April 2011

AbstractA coupled hydro-chemical-mechanical constitutive law for the Belgian Eurobitum bituminized waste is being developed by the International Centre for Numerical Methods and Engineering (Polytechnical University of Cataluña, Spain) to contribute to the study of the compatibility of Eurobitum with Boom Clay as a geological disposal environment. A large experimental programme is ongoing at SCK•CEN to support the development of a constitutive law for Eurobitum. Water uptake tests are being performed under different conditions to obtain insights in the parameters that influence the water uptake behaviour of Eurobitum. Furthermore, Environmental Scanning Electron Microscopy and microfocus X-ray Computer Tomography are used to characterize hydrated samples in order to improve the understanding of the water uptake processes.The salt content, the distribution of the salt crystals, and the membrane efficiency in the Eurobitum samples affect the swelling and pressure increase rate. High membrane efficiencies and a large amount of hygroscopic salts inside the Eurobitum samples result in very high pressures when almost no swelling is allowed. The pressure in small inactive samples with 28 wt.% NaNO3has risen to ∼19 MPa after ∼3 years of hydration in nearly constant volume conditions. Slower pressure increase rates are being measured for samples with 6, 12, 18, and 33 wt.% NaNO3.
Colloid and Radionuclide Transport in Granite Under Low Water Flow Rates Expected in a Geological Repository
Authors: Albarran Nairoby , Missana Tiziana , Alonso Ursula , Garcia-Gutierrez Miguel , Mingarro Manuel , Lopez Trinidad 
Published: April 2011

AbstractColloids generated from the engineered barriers of a high level radioactive waste repository (HLWR) emplaced in crystalline rock could play a significant role in radionuclide transport and they are of concern for the safety assessment of these repositories.The main objectives of this study are: a) to analyze the transport properties of colloids in a crystalline fractured rock under hydrodynamic conditions as similar as possible to those expected in a repository (i.e. low flow rates) and b) to discuss the effects of their presence on the transport of radionuclides.Transport experiments with bentonite and latex colloids in a fractured granite column from the Grimsel Test Site (Switzerland) were carried out, under geochemical conditions ensuring colloid stability (alkaline and low ionic strength water). Transport experiments were also carried out with 85Sr and 233U and the results with and without the presence of bentonite colloids were compared.Colloid filtration in the fracture was always observed, even when colloids presented high stability and the conditions were unfavorable to colloid attachment to rock surfaces, being both the colloids and the rock negatively charged and the fracture surface smooth. The retention in the fracture depended on the water flow rate, increasing the retention as the water flow decreased.This work illustrates as both the mobile and retained fraction of colloids, which strongly depend on the hydrodynamic conditions, are of importance in the overall radionuclide mobility.
Competitive Sorption of Metal Ions From Aqueous Solution Onto Sand
Authors: Morandi Sonia , Giacobbo Francesca , Mariani Mario , Ros Mirko Da 
Published: April 2011

AbstractThe major part of groundwater contaminants strongly interact with soils and aquifer rocks. Therefore sorption processes on porous matrix are of utmost importance in the frame of the nuclear waste disposal. The objectives of this study were to evaluate sorption uptake by silica sand of some safety-relevant metal ions such as Cs+, Sr2+, Cu2+, Ni2+ and to investigate the existence of competitive sorption processes between these ions. To this aim, kinetic and equilibrium, mono-component and multi-component, batch experiments were carried out in order to study: i) the influence of metal concentration, pH and contact time, on sorption onto silica sand of the above ions in aqueous solution, and ii) the presence of competition phenomena. Sorption data were well fitted by Langmuir and Freundlich models. Multi-component tests show that the uptake of each ion is reduced in presence of other ions in solution with respect to mono-component batch tests results and that competition between species appears influenced by the equilibrium times of the single species in solution and by pH.
Extending the SFR Repository in Order to Handle Decommissioning Waste From the Swedish NPPs
Authors: Vahlund Fredrik , Gordon Anna 
Published: April 2011

AbstractLow- and intermediate-level operational waste from the Swedish nuclear power plants is stored in the SFR repository. The facility is located in the bedrock at a depth of approximately 50 m and has been in operation for 20 years. According to present plans, all Swedish nuclear power plants will have been decommissioned by the end of the 2040s. The decommissioning phase will start by initially decommission the two Barseback reactors that have been non-operational since 1999 and 2005. In order to host the decommissioning waste, the storage volume of the SFR repository must be extended with approximately 140,000 m3. To do this, a project is ongoing with the objective of submitting an application to extend SFR by 2013 and the superior aim of having the facility in operation year 2020.
The Behaviours of Cementitious Materials in Long Term Storage and Disposal: An Overview of Results of the IAEA Coordinated Research Project
Authors: Drace Zoran , Ojovan Michael I. 
Published: April 2011

AbstractCementitious materials are widely used in waste management systems with different aims and requirements for long term performance. Both conventional and novel cementitious materials are used to create reliable immobilising elements for safe storage and disposal of wastes. The barrier elements as well as interactions envisaged between various components are important to ultimately ensure the overall safety of a storage/disposal system. The behaviour and performance of cementitious materials including waste package components, wasteform and backfilling were analysed within the IAEA Coordinated Research Project which involved 26 research organizations from 21 Member States MS). The paper presents briefly the main research outcomes for conventional cementitious systems; novel materials and technologies; testing and waste acceptance criteria; and modelling long term behaviour.
Enhanced Thermal Conductivity of Phase Change Materials Modified by Exfoliated Graphite Nanoplatelets
Authors: Xiang Jinglei , Drzal Lawrence 
Published: April 2011

AbstractComposite phase change materials (PCM) were prepared by mixing exfoliated graphite nanoplatelets (xGnP) into paraffin wax. The two types of graphite nanoplatelets that were investigated were xGnP-1 having thickness of 10 nm and a diameter of 1 um and xGnP-15 having the same thickness with a platelet diameter of 15 um. Direct casting and two roll milling were used to prepare samples. Scanning electron microscopy images show that the nanofillers disperse very well in paraffin matrix without noticeable agglomeration. Paraffin/xGnP-15 PCM consistently exhibited higher thermal conductivity than xGnP-1 PCM. The improvement in thermal conductivity was as high as 5 fold for xGnP-15 composites and 2 fold for xGnP-1 composites at 4 vol%. The aspect ratio, particle orientation, and interface density between the conductive particles and the polymer matrix were found to be the critical parameters in determining the conductivities of the resulting nanocomposites. The thermal physical properties of the nanocomposites were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). It was found that the latent heat of nanocomposites was not negatively affected in the presence of xGnP particles and the thermal stability improved.
Piezoelectric vibration harvesting device with automatic resonance frequency tracking capability
Authors: Defosseux Maxime , Marzencki Marcin , Basrour Skandar 
Published: April 2011

AbstractFurther development in the area of vibration energy harvesting is limited by the lack of efficient methods to adapt the harvester to its surroundings. To this end, we propose an innovative passive way of automatic passive resonance frequency tracking.We present a new approach employing mechanical non-linear behaviour of the system to track the vibration frequency peak. An analytical model representing these nonlinear harvesting systems has been developed and analysed. Experimental results obtained with custom fabricated MEMS devices show an experimentally verified frequency adaptability of over 36% for a clamped-clamped beam device at 2g (1g=9.81m.s-2) input acceleration. We believe that the proposed solution is perfectly suited for autonomous industrial machinery surveillance systems, where vibrations with high accelerations that are necessary for enabling this solution are abundant.
Characterization of the Corrosion Kinetic of X52 Steel in Seawater with Biocides
Authors: Galvan-Martinez R. , Orozco-Cruz R. , Torres-Sánchez R. , Martínez-Martinez E. A. 
Published: April 2011

ABSTRACTCorrosion study of the API X52 pipeline steel immersed in seawater without biocide and with 0.25, 0.5 and 0.75 ppm of biocide, under static and dynamic (turbulent flow) conditions was carried out at room temperature and atmospheric pressure. The hydrodynamic conditions were controlled by a rotating cylinder electrode (RCE) and the rotation speed was 1000 RPM. I order to analyse the corrosion process, linear polarization resistance (LPR), and polarization curves (PC) were made. This work investigation shown that the corrosion rate is higher under turbulent flow conditions than static conditions. A localized corrosion attacks was found in the superficial analysis.
Characterization of Strain Hardening Behavior and Residual Stress Induction Used For Crack Arrest in a Biocompatible Material
Authors: Urriolagoitia-Sosa G. , Molina-Ballinas A. , Urriolagoitia-Calderón G. , Hernández-Gómez L. H. , Sandoval-Pineda y J. M. 
Published: April 2011

ABSTRACTFor centuries, the manipulation of mechanical properties for the development of components has been extremely important. Its relevance is based on improving the service life in the components. The aim of some techniques that have been used is to introduce strain hardening (tensile) and a beneficial residual stress field. Nevertheless, the application of both methods is very common when the component is manufactured, but the lack of knowledge of the final physical state of the material could compromise the structural integrity of the final product. This work presents a numerical evaluation concerning the characterization of a stainless steel AISI 316L, having a homogeneous axial history and a residual stress field. The relevance of the work is focused in a new methodology that can be used to improve the mechanical resistance of the component and to arrest crack propagation. By altering the mechanical properties of the material, it could be possible to delay nucleation and interrupt the propagation of cracks. This study also shows that if the strain hardening behaviour and the introduction of the residual stress field is not done properly, it could result in a component susceptible to fail. In the same sense, bending tests are proposed to provide tensile and compressive stress profiles.
Synthesis and Characterization of Nanoparticles of TiO2
Authors: Lima García Rosa M. , Quintero-Torres Rafael 
Published: April 2011

ABSTRACTThe first steps in the synthesis of nanostructures are followed through UV-Vis and correlated with photoluminescence and images taken by SEM and TEM. Colloids permit the control in the atomic arrangement and the formation of nanostructures used to build cluster of materials. The size of the cluster in the colloid is around 5 nm. After the formation of the colloid a hydrothermal growth and microwave heating allows the formation of an ensemble of nano-sheet. This work is aim in the direction to controls the synthesis and the properties of materials with potential applications as active optical materials.
Preparation and Mechanical Properties of Polyethylene-Portland Cement Composites
Authors: L.P. Rivas-Vázquez , R. Suárez-Orduña , M. Valera-Zaragoza , De la L. Máas-Díaz A. , E. Ramírez-Vargas 
Published: April 2011

ABSTRACTThe effects of waste polyethylene aggregate as admixture agent in Portland cement at different addition polyethylene/cement ratios from 0.0156 to 0.3903 were investigated. The reinforced samples were prepared according the ASTM C 150 Standard (samples of 5 × 5 × 5 cm). The reinforcing fibers were milling at a size of 1/25 in diameter, form waste and used them to evaluate the effects in mechanical properties in cement-based composites. The evaluation of polyethylene as additive was based on results of density and compression tests. The 28-day compressive strength of cement reforced with plastic waste at a replacement polyethylene/cement ratio of 0.0468 was 23.5 MPa compared to the control concrete (7.5 MPa). The density of cement replaced with polyethylene varies from 2.114 (0% polyethylene) to 1.83 g/cm3 by the influence of polyethylene.
Spectroscopy Analysis of the Ring Opening Reaction in Functionalized Spiropyran Films
Authors: Delgado-Macuil Raúl J. , Rojas-López Marlon , Gayou Valentín L. , Orduña-Díaz Abdu , Díaz-Reyes Joel , Camacho-Pernas Virginia 
Published: April 2011

ABSTRACTIn this work we used the Fourier Transform Infrared spectroscopy and UV/Vis spectroscopy to analyze the behaviour of self-ensemble films of spiropyran when the films were irradiated by UV. In UV/Vis spectroscopy is possible observe the generation of the absorption peak, at 575 nm, associated to the merocyanine state when the ring-opening process is induced by UV light. In ATR the kinetics of the ring-opening was determinate too; following the spectra changes in real time.
The contribution of the N- and C- terminal domains to the stretching properties of intermediate filaments
Authors: Kreplak Laurent 
Published: April 2011

AbstractThe animal cell cytoskeleton consists of three interconnected filament systems: actin containing microfilaments (MFs), microtubules (MTs), and intermediate filaments (IFs). Among these three filaments systems, IFs are the only one that show high extensibility at both the single filament and network levels. In this work, I am presenting a simple model of IFs extensibility based on the current structural knowledge of the filaments. The only extra information added to this model compared to previous ones is the fact that the unfolded N- and C-termini of IF proteins are sandwiched between adjacent coiled-coil rod domains within the filaments. Since we know the contour length and typical persistence length of these unfolded termini, it is possible to predict the persistence length of a single filament, its maximal extensibility and the onset of coiled-coil unfolding. The predictions of the model are in good agreement with experiments on single desmin IFs stretched on a surface by AFM and on vimentin and desmin networks probed by rheology.
Mechanics of Collagen in the Human Bone: Role of Collagen-Hydroxyapatite Interactions
Authors: Katti Kalpana S , Pradhan Shashindra Man , Katti Dinesh R 
Published: April 2011

AbstractHere, we report results of our simulations studies on modeling the collagen-hydroxyapatite (HAP) interface in bone and influence of these interactions on mechanical behavior of collagen through molecular dynamics and steered molecular dynamics (SMD). Models of hexagonal HAP (10-10) and (0001) surface, and collagen with and without telopeptides were built to investigate the mechanical response of collagen in the proximity of mineral. The collagen molecule was pulled normal and parallel to the (0001) surface of hydroxyapatite. Water molecules were found have an important impact on deformation behavior of collagen in the proximity of HAP due to their large interaction energy with both collagen and HAP. Collagen appears stiffer at small displacement when pulled normal to HAP surface. At large displacement, collagen pulled parallel to HAP surface is stiffer. This difference in mechanical response of collagen pulled in parallel and perpendicular direction results from a difference in deformation mechanism of collagen. Further, the collagen molecule pulled in the proximity of HAP, parallel to surface, showed marked improvement in stiffness compared to absence of HAP. Furthermore, the deformation behavior of collagen not only depends on the presence or absence of HAP and direction of pulling, but also on the type of mineral surface in the proximity. The collagen pulled parallel to (10-10) and (0001) surfaces showed characteristically different type of load-displacement response. In addition, here we also report simulations on 300 nm length of collagen molecule indicating the role of length of model on the observed response in terms of both the magnitude of modulus obtained as well as the mechanisms of response of collagen to loading.
Humidity induced softening leads to apparent capillary effect in gecko adhesion
Authors: Chen Bin , Gao Huajian 
Published: April 2011

AbstractHumidity can lower the stiffness of beta keratin, which is the main component of spatula pads terminated at the bottom of a gecko's toe. To see if this softening can influence gecko adhesion, numerical simulation of the vertical peeling of a spatula pad adhered on a rough surface is performed, which shows that the reduction in material stiffness indeed leads to substantial increases in the pull-off force ″(Chen, B. and Gao, H. International Journal of Applied Mechanics, 2010). This work provides an alternative explanation of experimental observations on the capillary effect in gecko adhesion.