On Computations of Duct Acoustics with Near Cut-Off Frequency

Science.gov (United States)

Dong, Thomas Z.; Povinelli, Louis A.

1997-01-01

The cut-off is a unique feature associated with duct acoustics due to the presence of duct walls. A study of this cut-off effect on the computations of duct acoustics is performed in the present work. The results show that the computation of duct acoustic modes near cut-off requires higher numerical resolutions than others to avoid being numerically cut off. Duct acoustic problems in Category 2 are solved by the DRP finite difference scheme with the selective artificial damping method and results are presented and compared to reference solutions.

Experimental characterization of cement-bentonite interaction using core infiltration techniques coupled with 4D X-ray tomography

International Nuclear Information System (INIS)

Dolder, F.; Maeder, U.; Jenni, A.

2012-01-01

Document available in extended abstract form only. Deep geological disposal of radioactive waste foresee cementitious materials as reinforcement of tunnels, backfill, or as waste matrix. Bentonite, or sand-bentonite mixtures, are proposed as backfill material enclosing spent fuel drums, or as drift seals. The emplacement of cementitious material next to clay material generates an enormous chemical gradient in pore water, which drives diffusive transport. Laboratory studies and reactive transport modeling predict significant mineral alteration on both sides of interfaces, mainly resulting in a decrease of porosity in bentonite. The goal of the project is to characterize and quantify the cement/bentonite skin effects spatially and temporally. The expected analytical data set will be amenable to interpretation by reactive transport modeling. The project focuses on the advective-diffusive transport domain, resolved at intermediate spatial scales. The experiments are carried out in a newly developed X-ray transparent core infiltration apparatus, constructed from carbon fiber compounds and suitable for confining and infiltration pressures up to 80 bars. This setup allows to performing X-ray computed tomography scans (CT) periodically without interrupting the running core infiltration experiment. The experiment is performed on cylindrical bentonite samples (50 by 50 mm) compacted and saturated in-house with a dedicated device (Fig. 1, top). A sample is mounted in the core infiltration apparatus (Fig. 1, bottom) and subjected to a confining pressure in order to simulate underground repository conditions proposed by NAGRA (Swiss National Cooperative for the Disposal of Radioactive Waste). The infiltration of high-pH cement pore-fluids into the bentonite plug is expected to alter the mineral assemblage over time as an advancing reaction front. The related change in phase densities, porosity and bulk density is tracked over time recording periodically non-destructive CT scans

Modelling the Interaction of Low pH Cements and Bentonite. Issues Affecting the Geochemical Evolution of Repositories for Radioactive Waste

International Nuclear Information System (INIS)

Watson, Claire; Benbow, Steven; Savage, David

2007-05-01

It is well known that in the hyperalkaline conditions (pH > 12) of standard cement pore fluids, there is potential for deleterious effects upon the host rock and other EBS materials, notably bentonite, in geological repositories for radioactive waste. Low pH cements are beginning to be considered as a potential alternative material that may address some of these concerns. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non pozzolanic silica flour. NUMO, Posiva and SKB have defined a pH limit ≤ 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio ≤ 0.8. In this report we give the results of a preliminary modelling study to investigate the potential impacts of low pH cement water. We compare the evolution of a bentonite sample under the influence of several invading cement porewaters over a pH range from 10 to 13.2. The porewater compositions are taken from published CSH gel leaching experiments and published cement-bentonite modelling studies. The models suggest that the amount of degradation that is likely to be observed when low pH cement water interacts with bentonite is likely to be much less than when OPC water is the invading fluid. Below pH 11 there was not an observable Na montmorillonite dissolution front which would tend to support the pH ≤ 11 target suggested by NUMO, Posiva and SKB. The models used in this study could be improved upon by including a cement component to the model (rather than representing cement as a fixed boundary condition). Solid-solution models

European quality assurance and quality control for cut-off walls and caps

International Nuclear Information System (INIS)

Jefferis, S.A.

1997-01-01

Cut-off walls and caps both may be seriously compromised by small areas of substandard materials or work. Quality assurance/quality control is therefore of crucial importance and the paper sets out the issues that need to be addressed when designing a quality plan for a containment. Consideration is given to the purpose of the containment, the parameters to be controlled, specifications and standards and tests on raw and manufactured materials and on the in-situ containment. It is not the purpose of the paper to give detailed test procedures but rather to identify the questions that must be answered to develop a quality plan

Curing time effect on the fraction of 137Cs from cement- ion exchange resins-bentonite clay composition

International Nuclear Information System (INIS)

Plecas, I.; Dimovic, S.

2007-01-01

Curing conditions and time are critically important in leach studies since the extent of hydratation of the cement materials determines how much hydratation product develops and whether it is available to block the pore network, thereby reducing leaching.[1,2]. To assess the safety of disposal of radioactive waste material in cement, curing conditions and time of leaching radionuclide 137 Cs has been studied in this paper. Leaching tests in cement-ion exchange resins-bentonite matrix, were carried out in accordance with a method recommended by IAEA. Curing conditions and curing time prior to commencing the leaching test are critically important in leach studies since the extent of hydration of the cement materials determines how much hydration product develop and whether it is available to block the pore network, thereby reducing leaching. Incremental leaching rates R n (cm/d) of 137 Cs from cement-ion exchange resins-bentonite matrix after 180 days were measured. The results presented in this paper are examples of results obtained in a 20-year concrete testing project which will influence the design of the engineer trenches system for future central Serbian radioactive waste storing center. (author)

Pre-study on cementation processes in bentonite buffer under uneven saturation and temperature gradient

International Nuclear Information System (INIS)

Jaervinen, Joonas; Muurinen, Arto; Tanhua-Tyrkkoe, Merja

2012-01-01

Document available in extended abstract form only. Under final disposal conditions the uneven and slow saturation together with heat from the canister can lead to a situation where water vaporizes in certain areas in bentonite. The evaporation of ion rich water leads to enrichment of ions and precipitation of the components which may e.g. cement montmorillonite layers together and cause some changes in the bentonite properties. To study the cementation in bentonite buffer under uneven and slow saturation conditions the experimental setup was pre-modelled, constructed and tested. The experimental setups consist of a cylindrical cell (d:100 mm and h:100 mm), adsorption cells, heating system, hydration system, cooling system, sensors and a data acquisition system. A schematic drawing of the experimental equipment is presented in Figure 1. In the cell the hydration end of the bentonite was covered only partly by the sinter and the access of water to bentonite was thus limited. The cell was also equipped with holes in the upper part of the cylinder to allow the water vapour to escape from the cell. The released water vapour is collected on an adsorption material in the adsorption cells. Thermal and hydrological properties of the experimental system were pre-modelled in 2D by using TOUGH2, version 2.0. The aim of the model was to see if the planned experimental set-up leads to the wanted conditions, within reasonable time and to find justifiable parameters for experimental setup. An eleven months long pre-experiment was carried out to get preliminary understanding how the experimental arrangement works. After the experiment the cell was dismantled and water content, bulk density, CEC, exchangeable cations, poorly crystalline iron oxides and silicates, chloride, sulphate and carbonate were analysed and pH measured. The low water content and high chloride concentration next to the heater indicated movement of chloride ions from the hydration surface towards the heater and

Admixing dredged marine clay with cement-bentonite for reduction of compressibility

Science.gov (United States)

Rahilman, Nur Nazihah Nur; Chan, Chee-Ming

2017-11-01

Cement-based solidification/stabilization is a method that is widely used for the treatment of dredged marine clay. The key objective for solidification/stabilization is to improve the engineering properties of the originally soft, weak material. Dredged materials are normally low in shear strength and bearing capacity while high incompressibility. In order to improve the material's properties for possible reuse, a study on the one-dimensional compressibility of lightly solidified dredged marine clay admixed with bentonite was conducted. On the other hand, due to the viscous nature, particularly the swelling property, bentonite is a popular volumising agent for backfills. In the present study, standard oedometer test was carried out to examine the compressibility of the treated sample. Complementary strength measurements were also conducted with laboratory vane shear setup on both the untreated and treated dredged marine clay. The results showed that at the same binder content, the addition of bentonite contributed significantly to the reduction of compressibility and rise in undrained shear strength. These improved properties made the otherwise discarded dredged marine soils potentially reusable for reclamation works, for instance.

The effectivity of bentonites in cesium retention of cemented waste products

International Nuclear Information System (INIS)

Tello, Cledola Cassia Oliveira de

2001-01-01

The nuclear energy has been used for the human development in different areas, as in the medicine, in the agriculture, in the industry and in the environmental protection, besides the electricity generation. As in other activities, in the use of nuclear energy, residues are also generated. They are considered radioactive wastes when the contaminant content can bring a potential negative impact in the human health and in the environment. In this case they should be properly managed and should not be released without treatment. In general the waste processing consists in a volume reduction followed by solidification and/or conditioning. A number of materials can be considered as immobilisation matrices for the wastes, with the objective of maintain the radioactive material physical and chemically stable. The cement is extensively used because it is easy to obtain, there is large. experience in its use and the processing is done at room temperature. Many materials have been studied to improve the fixation characteristics of the radionuclides in the cemented product. The aim of this study was to search, among Brazilian natural materials, those that could be effective in the contaminant retention without jeopardising the process and other characteristics of the waste product. Four types of bentonite were selected to the process and product evaluation tests. Many mixtures were prepared with simulated waste, cement and bentonite in different proportions. The viscosity, set time, compressive strength and leaching were evaluated. In addition it was verified if the products were monolithic and without free water. Inactive caesium was used as tracer. The leaching resistance is the most important parameter in the product evaluation, because it indicates the retention capacity of the matrix for radionuclides when the product is in contact with the water. In 1985 leaching tests were begun and they have been continued till now and from their results it was proved that the

Experimental Investigation of Multi-mode Fiber Laser Cutting of Cement Mortar

Science.gov (United States)

2018-01-01

This study successfully applied multi-mode laser cutting with the variation of the laser cutting speed to cement mortar for the first time. The effects of the amount of silica sand in the cement mortar on laser cutting are tested and analyzed. The kerf width and penetration depth of the specimens after laser cutting are investigated. As the laser cutting speed increases, the penetration depth decreases for both cement paste and cement mortar, whereas the kerf width becomes saturated and increases, respectively, for cement paste and cement mortar. Cross sections of the specimens are compared with illustrations. Top-view images of the cement mortar with indicators of the physical characteristics, such as re-solidification, burning, and cracks are examined, and the possible causes of these characteristics are explained. The optical absorption rates of cement-based materials are quantified at wide ranges of wavelength to compare the absorption rates in accordance with the materials compositions. The chemical composition variation before and after laser cutting is also compared by EDX (Energy Dispersive X-Ray) analysis. In addition to these observations, material removal mechanisms for cement mortar are proposed. PMID:29439431

Experimental Investigation of Multi-mode Fiber Laser Cutting of Cement Mortar.

Science.gov (United States)

Lee, Dongkyoung; Pyo, Sukhoon

2018-02-10

This study successfully applied multi-mode laser cutting with the variation of the laser cutting speed to cement mortar for the first time. The effects of the amount of silica sand in the cement mortar on laser cutting are tested and analyzed. The kerf width and penetration depth of the specimens after laser cutting are investigated. As the laser cutting speed increases, the penetration depth decreases for both cement paste and cement mortar, whereas the kerf width becomes saturated and increases, respectively, for cement paste and cement mortar. Cross sections of the specimens are compared with illustrations. Top-view images of the cement mortar with indicators of the physical characteristics, such as re-solidification, burning, and cracks are examined, and the possible causes of these characteristics are explained. The optical absorption rates of cement-based materials are quantified at wide ranges of wavelength to compare the absorption rates in accordance with the materials compositions. The chemical composition variation before and after laser cutting is also compared by EDX (Energy Dispersive X-Ray) analysis. In addition to these observations, material removal mechanisms for cement mortar are proposed.

Mathematical modelling of transport phenomena in radioactive waste-cement-bentonite matrix

International Nuclear Information System (INIS)

Plecas, Ilija; Dimovic, Slavko

2010-01-01

Document available in extended abstract form only. The leaching rate of 137 Cs from spent mix bead (anion and cation) exchange resins in a cement-bentonite matrix has been studied. Transport phenomena involved in the leaching of a radioactive material from a cement-bentonite matrix are investigated using three methods based on theoretical equations. These are: the diffusion equation for a plane source an equation for diffusion coupled to a first-order equation and an empirical method employing a polynomial equation. The results presented in this paper are from a 25-year mortar and concrete testing project that will influence the design choices for radioactive waste packaging for a future Serbian radioactive waste disposal center. Radioactive waste is waste material containing radioactive chemical elements which does not have a practical purpose. It is often the product of a nuclear process, such as nuclear fission. Waste can also be generated from the processing of fuel for nuclear reactors or nuclear weapons. The main objective in managing and disposing of radioactive (or other) waste is to protect people and the environment. This means isolating or diluting the waste so that the rate or concentration of any radionuclides returned to the biosphere is harmless. Storage as the placement of waste in a nuclear facility where isolation, environmental protection and human control are provided with the intent that the waste will be retrieved at a later time. Disposal as the emplacement of waste in an approved, specified facility (e.g. near surface or geological repository) without the intention of retrieval. The processing of radioactive wastes may be done for economic reasons (e.g. to reduce the volume for storage or disposal, or to recover a 'resource' from the waste), or safety reasons (e.g. converting the waste to a more 'stable' form, such as one that will contain the radionuclide inventory for a long time). Typically processing involves reducing

The Use of Modified Bentonite for Removal of Aromatic Organics from Contaminated Soil.

Science.gov (United States)

Gitipour; Bowers; Bodocsi

1997-12-15

This study investigates the clay-aromatic interactions with a view to the use of bentonite clay for binding benzene, toluene, ethylbenzene, and o-xylene (BTEX compounds) in contaminated soils. BTEX compounds are the most toxic aromatic constituents of gasoline present in many underground storage tanks. Modified (organophilic) and ordinary bentonites are used to remove these organics. The organophilic bentonites are prepared by replacing the exchangeable inorganic cations present in bentonite particles with a quaternary ammonium salt. Various clay-to-soil ratios were applied to determine the efficiency of the modified bentonite in enhancing the cement-based solidification/stabilization (S/S) of BTEX contaminated soils. Toxicity characteristics leaching procedure (TCLP) tests were performed on soil samples to evaluate the leaching of the organics. In addition, X-ray diffraction analyses were conducted to assess the changes in the basal spacing of the clays as a result of their interaction with BTEX compounds. The findings of this study reveal that organophilic bentonite can act as a successful adsorbent for removing the aromatic organics from contaminated soil. Thus, this material is viable for enhancing the performance of cement-based S/S processes, as an adsorbent for petroleum spills, and for landfill liners and slurry walls. Copyright 1997 Academic Press.

The use of modified bentonite for removal of aromatic organics from contaminated soil

International Nuclear Information System (INIS)

Gitipour, S.; Bowers, M.T.; Bodocsi, A.

1997-01-01

This study investigates the clay-aromatic interactions with a view to the use of bentonite clay for binding benzene, toluene, ethylbenzene, and o-xylene (BTEX compounds) in contaminated soils. BTEX compounds are the most toxic aromatic constituents of gasoline present in many underground storage tanks. Modified (organophilic) and ordinary bentonites are used to remove these organics. The organophilic bentonites are prepared by replacing the exchangeable inorganic cations present in bentonite particles with a quaternary ammonium salt. Various clay-to-soil ratios were applied to determine the efficiency of the modified bentonite in enhancing the cement-based solidification/stabilization (S/S) of BTEX contaminated soils. Toxicity characteristics leaching procedure (TCLP) tests were performed on soil samples to evaluate the leaching of the organics. In addition, X-ray diffraction analyses were conducted to assess the changes in the basal spacing of the clays as a result of their interaction with BTEX compounds. The findings of this study reveal that organophilic bentonite can act as a successful adsorbent for removing the aromatic organics from contaminated soil. Thus, this material is viable for enhancing the performance of cement-based S/S processes, as an adsorbent for petroleum spills, and for landfill liners and slurry walls

Field test of ethanol/bentonite slurry grouting into rock fracture

International Nuclear Information System (INIS)

Motoyuki Asada; Hitoshi Nakashima; Takashi Ishii; Sumio Horiuchi

2006-01-01

Crystalline rocks have fractures which may cause unexpected routes of groundwater seepage. Cement grouting is one of the most effective methods to minimize seepage; however, cement materials may not be suitable for the purpose of extra-long durability, because cement is neutralized or degraded by chemical and physical influence of chemical reaction. Natural clay like bentonite is one of the most promising materials for seepage barrier; however, water/bentonite grout is so viscous that enough amount of bentonite can not be grouted into rock fractures. To increase bentonite content in grout with low viscosity, the utilization of ethanol as a mixing liquid was studied. Ethanol suppresses bentonite swelling, and more bentonite can be injected more than that of water/bentonite slurry. In this paper, grouting into in-situ rock mass fracture from the ground surface was tested to investigate the barrier performance and workability of ethanol/bentonite slurry as a grouting material. (author)

Properties of cement-fly ash grout admixed with bentonite, silica fume, or organic fiber

International Nuclear Information System (INIS)

Huang, W.H.

1997-01-01

A detailed laboratory study was conducted to investigate the properties of cement-fly ash grout mixtures as barriers for isolation of hazardous and low-level radioactive wastes. In the grout studied, fly ash was used to replace 30 percent by mass of cement. Three additives including bentonite, silica fume, and polypropylene fiber were used individually in the grout mixes to improve the properties of the grouts in different aspects. The flowability, bleeding, and setting time of freshly mixed grouts were determined; and the unconfined compressive strength, pore size distribution, and water permeability were determined for hardened grouts at various curing durations up to 120 days. Finally, the durability of cement-fly ash grouts was carefully examined in terms of the changes in their physical properties after different levels of exposure to sulfate attack and wet-dry cycles

A research paper of 'the basic sciences of the radioactive waste treatment' (Jul. 28,29, 1994) and 'Interface and surface science of solid waste processing and disposal -differences between cement and bentonite' (Dec. 14, 1995)

International Nuclear Information System (INIS)

1995-12-01

This report contains copies of OHP at the meetings of which discussions were centered upon the points of sameness and difference between cement and bentonite. There are sixteen papers, eleven in the first meeting and five in the second one. The following studies were read as under, on the first meeting, the role of retardation effect on the safety of high level atomic waste stratum processing, determination of colloid particle diameters by use of fieldflow fractionation, adsorption behavior of uranium, into black mica in granite, masstransfer mechanism of Cs and Se in the compression-bentonite, delay mechanism under conditions of mineral alteration, effects of humus on the behavior of radionuclides in stratum, formation of actinoids - humic acid complex and its effect on adsorption behavior, characteristic properties of water in bentonite, measurement of solubility of uranium and niobium, behavior of colloidal Am in the bentonite, illite - water system, effects of aging deterioration of bentonite on diffusion of nuclides, and on the second meeting, a view of cement materials, chemical behavior and long period stability of cement - relating to Atkinson model -, the present conditions of studies about sorption in cement, chemical properties of pore water in bentonite and interaction of bentonite and nuclides in solid - liquid interface. (S.Y.)

A research paper of `the basic sciences of the radioactive waste treatment` (Jul. 28,29, 1994) and `Interface and surface science of solid waste processing and disposal -differences between cement and bentonite` (Dec. 14, 1995)

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-12-01

This report contains copies of OHP at the meetings of which discussions were centered upon the points of sameness and difference between cement and bentonite. There are sixteen papers, eleven in the first meeting and five in the second one. The following studies were read as under, on the first meeting, the role of retardation effect on the safety of high level atomic waste stratum processing, determination of colloid particle diameters by use of fieldflow fractionation, adsorption behavior of uranium, into black mica in granite, masstransfer mechanism of Cs and Se in the compression-bentonite, delay mechanism under conditions of mineral alteration, effects of humus on the behavior of radionuclides in stratum, formation of actinoids - humic acid complex and its effect on adsorption behavior, characteristic properties of water in bentonite, measurement of solubility of uranium and niobium, behavior of colloidal Am in the bentonite, illite - water system, effects of aging deterioration of bentonite on diffusion of nuclides, and on the second meeting, a view of cement materials, chemical behavior and long period stability of cement - relating to Atkinson model -, the present conditions of studies about sorption in cement, chemical properties of pore water in bentonite and interaction of bentonite and nuclides in solid - liquid interface. (S.Y.)

Influence of cementation on the deformation properties of bentonite/quartz buffer substance

International Nuclear Information System (INIS)

Pusch, R.

1977-06-01

Cementation, e.g.precipitation of crystalline or solid amorphous inorganic substance between individual grains, greatly affects the mechanical properties of fine-grained soils. As concerns the buffer mass with the composition suggested (10 weight percent bentonite and 90% quartz particles) the intergranular contact pressure between the quartz particles will not be able to cause 'pressure solution'. Also, the other possible cementation effects will be negligible with the exception of the process which leads to precipitation of SiO 2 dissolved from quartz particles and enriched in the interstitial pore space. This process and its consequences will be treated in this report. The nature of silica solution and precipitation is not known in detail. The chemical environment, temperature, pH and ion strength are known to be controlling factors which combine to make possible alternating solution and precipitation of silica. However, as shown by the case survey and the presented theoretical treatment the amount of precipitated SiO 2 will not be able to produce a brittle behaviour of the buffer mass even after thousands of years

Containment barrier at Pride Park, Derby, England

International Nuclear Information System (INIS)

Barker, P.; Esnault, A.; Braithwaite, P.

1997-01-01

The Pride Park site at Derby occupies 96ha of derelict land close to the city centre. Approximately one third of the site was a closed landfill with a further third being an old gas works site. The remainder comprised former heavy engineering works and gravel pit workings. The River Derwent bounds the site on two sides. The objectives of the remediation strategy for the site included minimising off-site disposal of contaminated soils and ensuring that contaminants do not migrate into the adjacent river. The eastern part of the site, including the landfill and gasworks sites, was therefore contained by a 600mm wide bentonite cement vertical cut-off wall, with HDPE membrane, sealed by 1m into the underlying mudstone. The cut-off wall is some 3km long and a maximum 10m deep. The works were complicated by the need to construct the wall around 36 existing underground services. The paper briefly covers the background to the remediation of the site, describes the construction process and discusses design considerations in relation to the durability requirements of the containment barrier in the potentially aggressive environment

The distinct element analysis for swelling pressure test of bentonite. Discussion on the effects of wall friction force and aspect ratio of specimen

International Nuclear Information System (INIS)

Shimizu, Hiroyuki; Kikuchi, Hirohito; Fujita, Tomoo; Tanai, Kenji

2011-10-01

For geological isolation systems for radioactive waste, bentonite based material is assumed to be used as a buffer material. The swelling characteristics of the bentonite based material are expected to fill up the void space around the radioactive wastes by swelling. In general, swelling characteristics and properties of bentonite are evaluated by the laboratory tests. However, due to the lack of standardization of testing method for bentonite, the accuracy and reproducibility of the testing results are not sufficiently proved. In this study, bentonite swelling pressure test were simulated by newly developed Distinct Element Method (DEM) code, and the effects of wall friction force and aspect ratio of bentonite specimen were discussed. As a result, the followings were found. In the beginning of the swelling pressure test, since swelling occurs only around the fluid injection side of the specimen, wall friction force acts only in the swelling area and the specimen moves to opposite side from fluid injection side. However, when the entire specimen started swelling, displacement of the specimen prevented by the wall friction force, and the specimen is pressed against the pressure measurement side. Then, the swelling pressure measured on the pressure measurement side increases. Such displacement in the specimen is significantly affected by the decreasing of mechanical properties and the difference of saturation in the bentonite specimen during the fluid infiltration. Moreover, when the aspect ratio of the specimen is large, the displacement of the particle in the specimen becomes large and the area on which the wall frictional force acts is also large. Therefore, measured swelling pressure increases more greatly as the aspect ratio of the specimen increases. To contributes to the standardization of laboratory test methods for bentonite, these effects of wall friction force revealed by the DEM simulation should be verified through laboratory experiments. (author)

Low pH Cements

International Nuclear Information System (INIS)

Savage, David; Benbow, Steven

2007-05-01

The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit ≤ 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio ≤ 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

Low pH Cements

Energy Technology Data Exchange (ETDEWEB)

Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

2007-05-15

The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

Natural analogue study for interaction between alkaline groundwater and bentonite at Mangatarem region in the Philippines

International Nuclear Information System (INIS)

Tsukada, Y.; Fujita, K.; Nakabayashi, R.; Sato, T.; Yoneda, T.; Yamakawa, M.; Fujii, N.; Namiki, K.; Kasama, T.; Alexander, R.; Arcilla, C.; Pascua, C.

2012-01-01

Document available in extended abstract form only. Alteration of bentonite by alkaline leachate from cement/concrete in geological repositories for TRU radioactive waste is deleterious to bentonite performance as a buffer material. Although there have been many laboratory studies on high pH fluid-bentonite interaction for longer term understanding of the behavior of bentonites as buffer materials, different time scales between laboratory experiments and real disposal conditions impede its proper assessment. Thus, a natural analogue study can play an important role in (a) bridging the timescale gaps between laboratory experiments and real disposal conditions and (b) verifying the modeling studies of bentonite stability. Previous natural analogue studies on the cement-bentonite interaction are relatively few. Therefore, this study focuses on the process of serpentinization in ophiolitic rocks which resemble the process of leaching high pH ground waters from cement materials and report the results of study about alkaline water-bentonite interaction in Mangatarem, Philippines. In Mangatarem, in west central Luzon Island in the northern Philippines, there are bentonite quarries in the Aksitero Formation, which is part of the Zambales Ophiolite. Several alkaline hot springs derived from ongoing serpentinization of the ophiolite can be found in close proximity to the bentonite.Through a site characterization (including a foot survey, a series of boreholes and trench excavation in the Saile quarry in Mangatarem, the interface between the bentonite and the pillow lava of the upper ophiolite was confirmed, and chrysotile, a low temperature type of serpentine, was observed in the fault filling by XRD analysis. In the pillow lava, serpentine was also observed inside the fault that cut across both the bentonite and the pillow lava. From these facts, low temperature high pH fluids appears to have passed through the faults and came into contact with the bentonite. In order to

Experimental research on the durability cutting tools for cutting-off steel profiles

Directory of Open Access Journals (Sweden)

Cristea Alexandru

2017-01-01

Full Text Available The production lines used for manufacturing U-shaped profiles are very complex and they must have high productivity. One of the most important stages of the fabrication process is the cutting-off. This paper presents the experimental research and analysis of the durability of the cutting tools used for cutting-off U-shaped metal steel profiles. The results of this work can be used to predict the durability of the cutting tools.

Slurry walls and slurry trenches - construction quality control

International Nuclear Information System (INIS)

Poletto, R.J.; Good, D.R.

1997-01-01

Slurry (panel) walls and slurry trenches have become conventional methods for construction of deep underground structures, interceptor trenches and hydraulic (cutoff) barriers. More recently polymers mixed with water are used to stabilize the excavation instead of bentonite slurry. Slurry walls are typically excavated in short panel segments, 2 to 7 m (7 to 23 ft) long, and backfilled with structural materials; whereas slurry trenches are fairly continuous excavations with concurrent backfilling of blended soils, or cement-bentonite mixtures. Slurry trench techniques have also been used to construct interceptor trenches. Currently no national standards exist for the design and/or construction of slurry walls/trenches. Government agencies, private consultants, contractors and trade groups have published specifications for construction of slurry walls/trenches. These specifications vary in complexity and quality of standards. Some place excessive emphasis on the preparation and control of bentonite or polymer slurry used for excavation, with insufficient emphasis placed on quality control of bottom cleaning, tremie concrete, backfill placement or requirements for the finished product. This has led to numerous quality problems, particularly with regard to identification of key depths, bottom sediments and proper backfill placement. This paper will discuss the inspection of slurry wall/trench construction process, identifying those areas which require special scrutiny. New approaches to inspection of slurry stabilized excavations are discussed

Evaluation of long-term interaction between cement and bentonite for geological disposal (1) - Project Overview

International Nuclear Information System (INIS)

Owada, Hitoshi; Hayashi, Daisuke; Yahagi, Ryoji; Ishii, Tomoko

2012-01-01

the Ca/Na ratio of exchangeable cations, calculations of the dissolution rate of montmorillonite under cementitious conditions and quantitative analysis of the secondary minerals near the cement-bentonite interface were carried out. The results were then used to perform a coupled calculation of the long term alteration of the bentonite buffer. The type of secondary minerals and their spatial distribution are important issues for predicting the long term alteration of EBS materials. The secondary minerals that precipitated near the interfaces between the cementitious and bentonitic materials have not been identified before because of their minute quantity, the confined area, and their amorphous phases. In this study we attempted to identify the secondary minerals near the cementitious-bentonitic interfaces through the use of CaKa-XAFS spectroscopy. These secondary minerals were identified as C-S-H. Because the swelling and watertight properties of bentonite material strongly depend on its montmorillonite content, the dissolution rate of montmorillonite is an important issue for long term assessment of EBS performance. Although the dissolution rate of montmorillonite in suspension has been already obtained in other research, the rates in compacted bentonite are still in dispute. A lower dissolution rate was obtained in this study by using in-situ vertical scanning interferometry (VSI). Although there is empirical evidence that the mechanical and hydraulic properties of bentonite depend strongly on its montmorillonite content, the alteration of those properties has not been theoretically described very thoroughly. The relationship between montmorillonite content and mechanical properties was obtained by using a mixture of high-purity montmorillonite and silica sand. The change in hydraulic properties caused by chemical degradation such as cation exchange was modeled by applying the Cozeny-Carman equation to the specific surface area of montmorillonite before and after

Strength characteristics of lightly solidified dredged marine clay admixed with bentonite

Science.gov (United States)

Ariffin, Syazwana Tajul; Chan, Chee-Ming

2017-11-01

Strength characteristic is a significant parameter in measuring the effect of soil improvement and effective composition of solidification. In this study, the dredged marine sediment (DMS) collected from Kuala Perlis (Malaysia) was examined to determine its strength characteristics under light cement solidification with bentonite. Dredged marine clay generally has the low shear strength and high void ratio, and consists mainly of soil particles of the fine-grained type. As a discarded geo-waste, it can be potentially treated to for reuse as a backfill material instead of being disposed of, hence reducing the negative impact on the environment. Physico-chemical parameters of the dredged sample were first determined, then solidification was carried out to improve the engineering properties by admixing ordinary Portland cement (OPC) as the binder and bentonite as a volume enhancer to the soil. The DMS was treated with the addition of 3 % and 6 % cement and bentonite within the range of 0-30 %. The specimens were cured at room temperature for 3, 7 and 14 days. The strength gain was measured by unconfined compression test and vane shear test. The laboratory test results were analyzed to establish the relationship between strength properties and solidification specifications. In summary, the strength of specimens increased with the increase of the quantity of bentonite and cement to get the effective composition of the specimen.

COMP23 - Study of the connection between the hole in the canister wall and the surrounding bentonite

International Nuclear Information System (INIS)

Lindgren, M.; Widen, H.

1998-08-01

The input data in the near field compartment model concerning the connection between the hole in the canister wall and the surrounding bentonite has been studied. The calculations show that Z-AREA and A-ZERO must be given equal values in order to achieve consistent dimensions of the hole and the equivalent plug. The usage of an equivalent plug in the connection between the small hole and a large bentonite compartment is valid only if the hole is small compared to the area of the surrounding bentonite. It was shown that a hole with an area larger than about 0.001 m 2 overestimates the resistance between the hole and bentonite. An alternative is to make the model without the plug. However, in many cases with large hole the plug resistance is small compared to the total resistance and there is no need to take away the plug. In the case of an initially large hole it is better to exclude the plug from the model

Removal of oil from water by bentonite

International Nuclear Information System (INIS)

Moazed, H.; Viraraghavan, T.

1999-01-01

Many materials, included activated carbon, peat, coal, fiberglass, polypropylene, organoclay and bentonite have been used for removing oils and grease from water. However, bentonite has been used only rarely for this purpose. In this study Na-bentonite was used to remove oil from oil-in-water emulsions of various kinds such as standard mineral oil, cutting oils, refinery effluent and produced water from production wells at Estevan, Saskatchewan. Removal efficiencies obtained were 85 to 96 per cent for cutting oils, 84 to 86 per cent for produced water and 54 to 87 per cent for refinery effluent. Bentonite proved to be more effective in the removal of oil from oil-in-water emulsions than from actual waste waters; up to 96 percent from oil-in-water emulsions to only 87 per cent from actual waste water. The percentage of oil removed was found to be a function of the amount of bentonite added and the adsorption time up to the equilibrium time. Result also showed that the Langmuir, Freundlich and BET isotherms are well suited to describe the adsorption of oil by bentonite from the various oily waters employed in this study. 15 refs

Radioactive waste cementation

International Nuclear Information System (INIS)

Soriano B, A.

1996-01-01

This research was carried out to develop the most adequate technique to immobilize low and medium-activity radioactive waste. different brands of national cement were used, portland and pozzolanic cement. Prismatic and cylindrical test tubes were prepared with different water/cement (W/C) relationship. Additives such a as clay and bentonite were added in some other cases. Later, the properties of these test tubes were evaluated. Properties such as: mechanical resistance, immersion resistance, lixiviation and porosity resistance. Cement with the highest mechanical resistance values, 62,29 MPa was pozzolanic cement for a W/C relationship of 0,35. It must be mentioned that the other types of cements reached a mechanical resistance over 10 MPa, a value indicated by the international standards for transportation and storage of low and medium-activity radioactive waste at a superficial level. However, in the case of immersion resistance, Sol cement (portland type I) with a W/C relationship of 0,35 reached a compression resistance over 61,92 MPa; as in the previous cases, the other cements reached a mechanical resistance > 10 MPa. Regarding porosity, working with W/C relationships = 0,35 0,40 and 0,45, without additives and with additives, the percentage of porosity found for all cements is lower than 40% percentage indicated by international standards. With regard to the lixiviation test, pozzolanic cement best retained Cesium-137 and Cobalt-60, and increased its advantages when bentonite was added, obtaining a lixiviation rate of 2,02 x E-6 cm/day. Sol cement also improved its properties when bentonite was added and obtained a lixiviation rate of 2,84 x E-6 cm/day for Cesium-137. However, Cobalt-60 is almost completely retained with the 3 types of cement with or without additives, reaching the limits indicated by the international standards for the lixiviation rate of beta-gamma emitter < 5,00E-4 cm/day. Characterizing the final product involves the knowledge of its

Fatigue life analysis of cracked gas receiver of emergency cut-off system in gas gathering station

Science.gov (United States)

Hu, Junzhi; Zhou, Jiyong; Li, Siyuan

2017-06-01

Small-scale air compressor and gas receiver are used as the driving gas of the emergency cut-off system in gas gathering station. Operation of block valve is ensured by starting and stopping compressor automatically. The frequent start-stop of compressor and the pressure fluctuation pose a threat to the service life of gas receiver, and then affect normal operation of the emergency cut-off system and security of gas gathering station. In this paper, the fatigue life of a pressure vessel with axial semi-elliptical surface crack in the inner wall is analyzed under the varying pressure by means of the theory of fracture mechanics. The influences of the amplitude of pressure fluctuation and the initial crack size on the residual life of gas receiver are discussed. It provides a basis for setting the working parameters of gas receiver of emergency cut-off system and determining the maintenance cycle.

Phase- and size-adjusted CT cut-off for differentiating neoplastic lesions from normal colon in contrast-enhanced CT colonography

International Nuclear Information System (INIS)

Luboldt, W.; Kroll, M.; Wetter, A.; Vogl, T.J.; Toussaint, T.L.; Hoepffner, N.; Holzer, K.; Kluge, A.

2004-01-01

A computed tomography (CT) cut-off for differentiating neoplastic lesions (polyps/carcinoma) from normal colon in contrast-enhanced CT colonography (CTC) relating to the contrast phase and lesion size is determined. CT values of 64 colonic lesions (27 polyps 0 . The slope m was determined by linear regression in the correlation (lesion ∝[xA + (1 - x)V]//H) and the Y-intercept y 0 by the minimal shift of the line needed to maximize the accuracy of separating the colonic wall from the lesions. The CT value of the lesions correlated best with the intermediate phase: 0.4A+ 0.6V(r=0.8 for polyps ≥10 mm, r=0.6 for carcinomas, r=0.4 for polyps <10 mm). The accuracy in the differentiation between lesions and normal colonic wall increased with the height implemented as divisor, reached 91% and was obtained by the dynamic cut-off described by the formula: cut-off(A,V,H) = 1.1[0.4A + 0.6V]/H + 69.8. The CT value of colonic polyps or carcinomas can be increased extrinsically by scanning in the phase in which 0.4A + 0.6V reaches its maximum. Differentiating lesions from normal colon based on CT values is possible in contrast-enhanced CTC and improves when the cut-off is adjusted (normalized) to the contrast phase and lesion size. (orig.)

Long-term stability of bentonite. A literature review

International Nuclear Information System (INIS)

Laine, H.; Karttunen, P.

2010-07-01

The long-term thermodynamic stability of the bentonite buffer in the evolving chemical, thermal and hydrological conditions at Olkiluoto has been evaluated by reviewing the relevant experimental data and natural occurrences of bentonite that could serve as analogues for the long-term bentonite stability in the expected repository conditions, especially focussing on mineral transformations due, among others, to thermal effects including cementation. Natural occurrences with stable smectite have been reviewed and compared with Olkiluoto groundwater compositions at present and during the expected hydrogeochemical evolution of the repository. Alteration of the bentonite buffer is expected to be insignificant for natural groundwater conditions at present and for the evolving groundwater conditions at the expected thermal boundary conditions caused by the heat induced from the fuel canisters ( + and SiO 2 and elevated pH due to degradation and dissolution processes. These may alter the conditions in the repository that may favour alteration and cementation processes. The amounts of foreign materials to be used in the repository will be updated along with the progress of the construction. Also the information on their impact on the barriers needs to be evaluated in more detail, including the degradation rate, mobility or dilution of the foreign materials in the repository environment. The exchangeable cation composition of the buffer bentonite is expected to equilibrate with the surrounding groundwater during and after saturation. This process is expected to lead towards Ca-dominant exchangeable cation composition within the montmorillonite interlayer spaces in the buffer. In general it seems that the transformation towards Ca-dominated composition would favour the long-term stability of the buffer as Ca-dominated smectite (compared to Na-dominated type) has larger water retention capacity and anion incorporation to the interlayer space of montmorillonite is more

Evaluation of gas migration characteristics of compacted bentonite and Ca-bentonite mixture

International Nuclear Information System (INIS)

Tanaka, Yukihisa; Hironaga, Michihiko

2014-01-01

In the current concept of subsurface disposal and near-surface pit disposal for low level radioactive waste, compacted bentonite and Ca-bentonite mixture will be used as an engineered barrier mainly for inhibiting migration of radioactive nuclides, respectively. Hydrogen gas can be generated inside the engineered barrier of subsurface disposal facilities mainly by anaerobic corrosion of metals used for containers, etc. Hydrogen gas can be also generated inside the engineered barrier of near-surface pit disposal facilities mainly by the chemical interaction between aluminum and the alkaline component of cement, or water. If the gas generation rate exceeds the diffusion rate of gas molecules inside of the compacted bentonite and Ca-bentonite mixture, gas will accumulate in the void space inside of the compacted bentonite and Ca-bentonite mixture until breakthrough occurs. It is expected to be not easy for gas to entering into the compacted bentonite mixture as a discrete gaseous phase because the pore of the compacted bentonite and Ca-bentonite mixture is so minute. Therefore in this study, the gas migration characteristics and the effect of gas migration on the hydraulic conductivity of the compacted bentonite and Ca-bentonite mixture are investigated by the gas migration tests. The applicability of the two phase flow model without considering deformability of the specimen is investigated. The applicability of the model of two phase flow through deformable porous media, which was originally developed by CRIEPI, is also investigated. Results of this study imply that : (1) Gas migration mechanism of the compacted bentonite and Ca-bentonite mixture is revealed through gas migration test. (2) Hydraulic conductivity measured after the large gas breakthrough is substantially the same that measured before the gas migration test. (3) Stress change, pore-water pressure change and volume change of the specimen during the gas migration test can be reproduced by the numerical

Diffusion of radionuclides in concrete/bentonite systems

International Nuclear Information System (INIS)

Albinsson, Y.; Boerjesson, S.; Andersson, K.; Allard, B.

1993-02-01

In a repository for nuclear waste, different construction materials will be used. Two important materials among these are concrete and bentonite clay. These will act as mechanical barriers, preventing convective water flow and also retard transport due to diffusion of dissolved radionuclides by a combination of mechanical constraints and chemical interactions with the solid. An important issue is the possible change of the initial sodium bentonite into the calcium form due to ion exchange with calcium from the cement. The initial leaching of the concrete has been studied using radioactive spiked concrete in contact with compacted bentonite. The diffusion of Cs, Am and Pu into 5 different types of concrete in contact with porewater have been measured. The measured diffusivity for Cs agrees reasonable well with data found in literature. For Am and Pu no movement could be measured (less than 0.2 mm) even though the contact times were extremely long (2.5 y and 5 y, respectively). This report gives also a summary of the previously published results about sorption and diffusion of radionuclides in cement performed in Prav/KBS/SKB projects 1980-1990. 25 refs

Cut-off frequency of magnetostrictive materials based on permeability spectra

International Nuclear Information System (INIS)

Meng Hao; Zhang Tianli; Jiang Chengbao

2012-01-01

The loss behavior and cut-off frequency of TbDyFe alloy and TbDyFe/epoxy composite have been investigated by measuring their permeability spectra. The loss factor of TbDyFe alloy increases exponentially as the frequency goes up, while it is almost unchanged for the TbDyFe/epoxy composite. The loss factor value for the TbDyFe composite is only 4.3% of that for the monolithic TbDyFe alloy at high frequency of 10 kHz under the peak magnetic induction of 10 mT. The cut-off frequency of TbDyFe/epoxy composite is 6800 kHz, 3 orders of magnitude larger than that of TbDyFe alloy. The cut-off frequency is found to be the ferromagnetic resonance frequency and can be calculated from Snoek's law. - Highlights: ► The cut-off frequency of TbDyFe alloy and TbDyFe/epoxy composite has been investigated. ► Permeability spectra are used to study loss behavior and cut-off frequency. ► A mathematic formula is deduced to predict the cut-off frequency. ► TbDyFe/epoxy composite presents high cut-off frequency of 6800 kHz.

Cut-off Grade Optimization for Maximizing the Output Rate

Directory of Open Access Journals (Sweden)

A. Khodayari

2012-12-01

Full Text Available In the open-pit mining, one of the first decisions that must be made in production planning stage, after completing the design of final pit limits, is determining of the processing plant cut-off grade. Since this grade has an essential effect on operations, choosing the optimum cut-off grade is of considerable importance. Different goals may be used for determining optimum cut-off grade. One of these goals may be maximizing the output rate (amount of product per year, which is very important, especially from marketing and market share points of view. Objective of this research is determining the optimum cut-off grade of processing plant in order to maximize output rate. For performing this optimization, an Operations Research (OR model has been developed. The object function of this model is output rate that must be maximized. This model has two operational constraints namely mining and processing restrictions. For solving the model a heuristic method has been developed. Results of research show that the optimum cut-off grade for satisfying pre-stated goal is the balancing grade of mining and processing operations, and maximum production rate is a function of the maximum capacity of processing plant and average grade of ore that according to the above optimum cut-off grade must be sent to the plant.

Cut-off of electric consumption in France. Assessment of the cut-off potential by process modulation in industrial and tertiary sectors in metropolitan France. Final report + Synthesis

International Nuclear Information System (INIS)

Bertholon, Marion; Streiff, Frederic; Marchal, David; Bouchet, Alexandre; Foucher, Julie-Anne; Hoffer, Alexandre; Millet, Bruno; Sorlier, Pierre; Peron, Nicolas; Creon, Nicolas; Lenet, Sylvain; Guillet, Frederic; Mounier, Cyril; Charton, Franck; Duclos, Herve; Lenain, Yves; MADEC, Marc; Lepretre, Pascale; Vasseur, Olivier; Rigard-Cerison, Aude; Guedou, Benjamin; Houvenagel, Olivier; Epelbaum, David; Briant, Marie-Helene; Osmont, Robin; Elasri, Sofia; Barreyre, Gildas; Adam, Julien

2017-09-01

This study mainly aims at characterising and assessing the cut-off potential in the French industrial and tertiary sectors by providing qualitative as well as quantitative elements, and by highlighting the different mechanisms of valorisation of existing and currently developed cut-off. It also proposes a comparison of the French context with that of some foreign countries (notably United Kingdom, Japan, and some regions of the USA). Thus, it comprises an identification and analysis of cut-off mechanisms and practices, an assessment of technical and technical-economic cut-off sources in France, and a discussion of economic and organisational brakes and obstacles to cut-off developments

Bentonite as a backfill material for shallow land repositories

International Nuclear Information System (INIS)

Yalmali, V.S.; Deshingkar, D.S.

2001-01-01

Two commercially available indigenous bentonite samples were evaluated for their cesium and strontium sorption properties in distilled water and surface water. By converting them into sodium form, the distribution coefficients for both cesium (I) and strontium (II) increased. Sodium bentonite was recommended because of high sorption capacity for Cs(I), Mg(II) and Sr(II) for use as backfill material in shallow land repositories where cement waste form containing Cs, Sr and Be wastes are disposed. (author)

Experimental evaluation of the hydraulic resistance of compacted bentonite/boom clay interface

International Nuclear Information System (INIS)

Tang, Anh-Minh; Cui, Yu-Jun; Delage, Pierre; Munoz, Juan Jorge; Li, Xiang-Ling

2008-01-01

In the framework of the in-situ PRACLAY Heater experiment to be performed in the HADES URF in Mol (Belgium), the feasibility of a hydraulic cut-off of the Excavation Damaged Zone (EDZ) and the Repository Components (RC) of the disposal galleries by using a horizontal seal will be examined. It has been planned to install an annular seal composed of compacted bentonite between the heated zone and the access gallery (PRACLAY seal test), so that to avoid any hydraulic shortcut towards the access gallery. According to numerical scoping calculations, heating until 80 deg C will induce a pore pressure of the order of 3.0 MPa. In order to verify the effects of this water pressure on the performance of the annular seal system and more specifically on the hydraulic resistance of the interface between the compacted bentonite and the host rock (Boom clay), laboratory percolation tests at 20 and 80 deg C were performed. The results confirm the performance of the compacted bentonite seal to avoid the hydraulic shortcut to the access gallery under the foreseen hydraulic and thermal conditions. (author)

The influence of mineral additives on the mechanical performances of the conditioning matrix of radioactive waste by cementation

International Nuclear Information System (INIS)

Dragolici, F.; Rotarescu, G.; Turcanu, C.N.

1997-01-01

To improve the quality of the conditioning matrix of radioactive waste by the cementation technology, mineral additives which are diminishing the leaching rate of the radionuclides in the disposal environment are used. The studies performed until now have as an objective the obtaining of the most propitious mixture of cement and bentonite or cement and volcanic tuff, which have the mechanical properties similar to the cement paste used for the conditioning of the radioactive waste. This mixture, cement - mineral binder, in the future is required to be used at the Radioactive Waste Treatment Plant - IPNE - HH Bucharest- Magurele for the conditioning of the radioactive wastes, taking in consideration the properties of these mineral binders: very good plasticity and capacity of adsorption, which lead at the decrease of porosity. Bentonite is a clay already used in the technology of disposal as a filling material to diminish the radioactive spreading because of degradation in time of the metallic package or the intrusion of casual water. The composition of the cement - bentonite - water system is checked by the cement to water and cement to bentonite ratio, by strength and by the separated water volume. The studies show that the best mechanical performance was obtained for a cement to water ratio 10. Taking in consideration the property of bentonite to fill compactly the free spaces in the presence of water, what entails the occurrence of internal tensions in the matrix structure, which leads, in turn, to appearance of microfissures, the mixtures examined by mechanical tests had in their composition less than 10 % bentonite. For volcanic tuff, similar results were obtained using almost the same ratios. In these conditions, the results obtained allow to draw the conclusion that the adequate usage of the mineral additives do not change the resistance of the cement paste used in the conditioning of the radioactive waste. (authors)

Ag-catalysed cutting of multi-walled carbon nanotubes

International Nuclear Information System (INIS)

La Torre, A; Rance, G A; Miners, S A; Lucas, C Herreros; Smith, E F; Giménez-López, M C; Khlobystov, A N; Fay, M W; Brown, P D; Zoberbier, T; Kaiser, U

2016-01-01

In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon–carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes. (paper)

Influence of natural sorbents in immobilization of radioactive waste in cement

International Nuclear Information System (INIS)

Plecas, I.; Dimovic, S.

2006-01-01

Leach characteristics of 137 Cs and 60 Co radionuclides from spent mix bead ion exchange resins and both ordinary Portland cement and cement mixed with two kind of natural sorbents, (bentonite and clinoptilolite) have been studied using International Atomic Energy's (IAEA) standard leach method. A study is undertaken to determine the waste immobilization performance of low-level wastes in cement-natural sorbents mixtures. The solidification matrix was a standard Portland cement mixed with 290-350 (kg/m 3 ) spent mix bead exchange resins, with or without 1-10 % of bentonite or/and clinoptilolite The leaching rates from the cement-bentonite matrix as 60 Co: (1.20-9.72)x10 -5 (cm/d) and for 137 Cs: (1.00-9.22)x10 -4 (cm/d), after 300 days were measured. From the leaching data the apparent diffusivity of cobalt and cesium in cement bentonite or/and clinoptilolite matrix with a waste load of 350 (kg/m 3 ) spent mix bead exchange resins was measured as 60 Co: (1.0-5.9)x10 -6 (cm 2 /d) and for 137 Cs: (0.48-2.4)x10 -4 (cm 2 /d) after 300 days. The compressive strength of these samples is determined following the ASTM standards. These results are part of a 30-year mortar and concrete testing project which will influence the design of radioactive waste management for a future Serbian radioactive waste disposal center. (author)

Hydrothermal alkaline stability of bentonite barrier by concrete interstitial wastes

International Nuclear Information System (INIS)

Leguey Jimenez, S.; Cuevas Rodriguez, J.; Ramirez Martin, S.; Vigil de la villa Mencia, R.; Martin Barca, M.

2002-01-01

At present, the main source of High Level radioactive Waste (HLW) is the electrical energy production during all the steps of developing. In almost all the countries with nuclear programs, the option for the final management of HLW is the Deep Geological Repository (DGR) based on the concept of multi barrier. According to this concept, the waste is isolated from biosphere by the interposition of confinement barriers. Two of the engineering barriers in the Spanish design of DGR in granitic rock are compacted bentonite and concrete. The bentonite barrier is the backfilling and sealing material for the repository gallery, because of its mechanical and physico-chemical properties. The main qualities of concrete as a component of a multi barrier system are its low permeability, mechanical resistance and chemical properties. With regard to chemical composition of concrete, the alkaline nature of cement pore water lowers the solubility of many radioactive elements. However, structural transformation in smectite, dissolution or precipitation of minerals and, consequently, changes in the bentonite properties could occurs in the alkaline conditions generated by the cement degradation. The main objective of the present work is to evaluate the effect of concrete in the stability of Spanish reference bentonite (La Serrata of Nijar, Almeria, Spain) in conditions similar to those estimated in a DGR in granitic rock. Because of the main role of bentonite barrier in the global performance of the repository, the present study is essential to guarantee its security. (Author)

Critical test of isotropic periodic sum techniques with group-based cut-off schemes.

Science.gov (United States)

Nozawa, Takuma; Yasuoka, Kenji; Takahashi, Kazuaki Z

2018-03-08

Truncation is still chosen for many long-range intermolecular interaction calculations to efficiently compute free-boundary systems, macromolecular systems and net-charge molecular systems, for example. Advanced truncation methods have been developed for long-range intermolecular interactions. Every truncation method can be implemented as one of two basic cut-off schemes, namely either an atom-based or a group-based cut-off scheme. The former computes interactions of "atoms" inside the cut-off radius, whereas the latter computes interactions of "molecules" inside the cut-off radius. In this work, the effect of group-based cut-off is investigated for isotropic periodic sum (IPS) techniques, which are promising cut-off treatments to attain advanced accuracy for many types of molecular system. The effect of group-based cut-off is clearly different from that of atom-based cut-off, and severe artefacts are observed in some cases. However, no severe discrepancy from the Ewald sum is observed with the extended IPS techniques.

Statistical study of chemical additives effects in the waste cementation

International Nuclear Information System (INIS)

Tello, Cledola C.O. de; Diniz, Paula S.; Haucz, Maria J.A.

1997-01-01

This paper presents the statistical study, that was carried out to analyse the chemical additives effect in the waste cementation process. Three different additives from two industries were tested: set accelerator, set retarder and super plasticizers, in cemented pates with and without bentonite. The experiments were planned in accordance with the 2 3 factorial design, so that the effect of each type of additive, its quantity and manufacturer in cemented paste and specimens could be evaluated. The results showed that the use of these can improve the cementation process and the product. The admixture quantity and the association with bentonite were the most important factors affecting the process and product characteristics. (author). 4 refs., 9 figs., 4 tabs

Cut-off parameters in the one-dimensional two-fermion model

International Nuclear Information System (INIS)

Apostol, M.

1982-07-01

It is shown that the usual cut-off procedure (α cut-off parameter) employed in the boson representation of the fermion field opepators of the one-djmensional two-fermion model (TFM) is an incorrect one as the computator of the hermitean-conjugate field operators at the same space-point fails to fulfil a certain relationship which was pointed out long ago by Jordan. The complete form of the boson representation (including the zero-mode) of a single fermion field and the correct values of the cut-off parameter α is reviewed following Jordan and generalized to the TFM. The cut-off parameter α corresponds to a bandwidth cut-off and Jordan's boson representation is exact only in the limit α → 0. The additional zero-mode terms make the exact solution of the backscattering and umklapp scattering problem to be valid only if a supplementary condition is imposed on the coupling constants. Using the present bosonization technique all the inconsistencies of the TFM are removed. The one-particle Green's function and response functions of the Tomonaga-Luttinger model (TLM) are calculated and found to be identical with those obtained by direct diagram summation. The energy gap appearing in the spectrum of the TFM with backscattering and umklapp scattering for certain values of the coupling constants is shown to be proportional to the momentum transfer cut-off γ -1 which has to be kept finite while α goes to zero. Under such conditions the anticommunication relations and Jordan's commutator are invariant under the canonical transformation on the boson operators that diagonalizes the Hamiltonian of the TLM. The charge-density response function of the TFM with backscattering is perturbationally calculated up to the first order. The cut-off α -1 applies in the same way to terms which differ only by their spin indices in the expression of this response function. The charge-density response function is also evaluated at low frequencies for the exactly soluble TFM with

Establishing pathological cut-offs for lateral ventricular volume expansion rates

Directory of Open Access Journals (Sweden)

Michael G. Dwyer

Full Text Available Background: A percent brain volume change (PBVC cut-off of −0.4% per year has been proposed to distinguish between pathological and physiological changes in multiple sclerosis (MS. Unfortunately, standardized PBVC measurement is not always feasible on scans acquired outside research studies or academic centers. Percent lateral ventricular volume change (PLVVC is a strong surrogate measure of PBVC, and may be more feasible for atrophy assessment on real-world scans. However, the PLVVC rate corresponding to the established PBVC cut-off of −0.4% is unknown. Objective: To establish a pathological PLVVC expansion rate cut-off analogous to −0.4% PBVC. Methods: We used three complementary approaches. First, the original follow-up-length-weighted receiver operating characteristic (ROC analysis method establishing whole brain atrophy rates was adapted to a longitudinal ventricular atrophy dataset of 177 relapsing-remitting MS (RRMS patients and 48 healthy controls. Second, in the same dataset, SIENA PBVCs were used with non-linear regression to directly predict the PLVVC value corresponding to −0.4% PBVC. Third, in an unstandardized, real world dataset of 590 RRMS patients from 33 centers, the cut-off maximizing correspondence to PBVC was found. Finally, correspondences to clinical outcomes were evaluated in both datasets. Results: ROC analysis suggested a cut-off of 3.09% (AUC = 0.83, p < 0.001. Non-linear regression R2 was 0.71 (p < 0.001 and a − 0.4% PBVC corresponded to a PLVVC of 3.51%. A peak in accuracy in the real-world dataset was found at a 3.51% PLVVC cut-off. Accuracy of a 3.5% cut-off in predicting clinical progression was 0.62 (compared to 0.68 for PBVC. Conclusions: Ventricular expansion of between 3.09% and 3.51% on T2-FLAIR corresponds to the pathological whole brain atrophy rate of 0.4% for RRMS. A conservative cut-off of 3.5% performs comparably to PBVC for clinical outcomes. Keywords: Brain atrophy

The effectivity of bentonites in cesium retention of cemented waste products; Efetividade das bentonitas na retencao de cesio em produtos de rejeitos cimentados

Energy Technology Data Exchange (ETDEWEB)

Tello, Cledola Cassia Oliveira de

2001-01-15

The nuclear energy has been used for the human development in different areas, as in the medicine, in the agriculture, in the industry and in the environmental protection, besides the electricity generation. As in other activities, in the use of nuclear energy, residues are also generated. They are considered radioactive wastes when the contaminant content can bring a potential negative impact in the human health and in the environment. In this case they should be properly managed and should not be released without treatment. In general the waste processing consists in a volume reduction followed by solidification and/or conditioning. A number of materials can be considered as immobilisation matrices for the wastes, with the objective of maintain the radioactive material physical and chemically stable. The cement is extensively used because it is easy to obtain, there is large. experience in its use and the processing is done at room temperature. Many materials have been studied to improve the fixation characteristics of the radionuclides in the cemented product. The aim of this study was to search, among Brazilian natural materials, those that could be effective in the contaminant retention without jeopardising the process and other characteristics of the waste product. Four types of bentonite were selected to the process and product evaluation tests. Many mixtures were prepared with simulated waste, cement and bentonite in different proportions. The viscosity, set time, compressive strength and leaching were evaluated. In addition it was verified if the products were monolithic and without free water. Inactive caesium was used as tracer. The leaching resistance is the most important parameter in the product evaluation, because it indicates the retention capacity of the matrix for radionuclides when the product is in contact with the water. In 1985 leaching tests were begun and they have been continued till now and from their results it was proved that the

Using Frozen Barriers for Containment of Contaminants

Science.gov (United States)

2017-09-21

barriers are constructed of grout slurry and plastic or steel sheet pilings. Circumferential barriers can be used to completely enclose a source of...2.1.1 Slurry walls A soil-bentonite slurry trench cutoff wall (slurry wall) is excavated and backfilled with grout, cement , or soil-bentonite...installation requires a mixing area, and there is a substantial amount of excavation and the need to dispose of spoil. The advantages of cement -based

Bentonite as a colloid source in groundwaters at Olkiluoto

International Nuclear Information System (INIS)

Vuorinen, U.; Hirvonen, H.

2005-02-01

In this work bentonite was studied as a potential source of colloids in Olkiluoto groundwaters. Samples were collected at two groundwater stations, PVA1 at 37.5 m dept and PVA3 at 95.6 m depth, in the VLJ-tunnel. The deeper groundwater at PVA3 was more saline (2.6g/L of Cl-) than the shallow at PVA1 (0.8g/L of Cl-). A bentonite source had been assembled at each groundwater station so that two sample lines were available for water samples; one for collecting a sample before and the other for collecting a sample after interaction with bentonite. Before starting the actual colloid sampling groundwaters from both sample lines at both stations were analysed. Only minor alterations, mostly within the uncertainty limits of the analysis methods, were brought about in the water chemistries after interaction with the bentonite sources. The only clear changes were seen in the concentration of iron which decreased after interaction with bentonite in the groundwaters at both stations. After groundwater sampling the actual colloid sampling was performed. The water samples were collected and treated inside a movable nitrogen filled glove-box. The samples could be collected from each sampling line directly in the glove-box via two quick-couplings that had been assembled on the front face of the box. The sample lines had been assembled with 0.45 μm filters before entering the glove-box, because only colloids smaller than 0.45 μm were of interest, as they are not prone to sedimentation in slow groundwater flows and therefore could act as potential radionuclide carriers. Colloid samples were collected and treated similarly from both sampling lines at both groundwater stations. For estimating the colloid content the groundwater samples were filtered with centrifugal ultrafiltration tubes of different cut-off values (0.3 μm, 300kD and 10kD). The ultrafiltrations produced the colloid-containing concentrate fractions and the soluble substances-containing filtrate fractions. In

Brazilian bentonite study: use in Goiania; Estudo das bentonitas nacionais: utilizacao em Goiania

Energy Technology Data Exchange (ETDEWEB)

Tello, Cledola Cassia Oliveira de [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

1997-12-31

The evaluation of the bentonite effect in the waste cementation process and in the final solidified product properties is presented. The research showed that bentonite amounts until 15% in the product improves the caesium retention without jeopardizing the other product properties. These results were very useful in the treatment of the wastes from the radiological accident occurred in Goiania in 1987, when a caesium sources was broken. Paste, mortar and grout with bentonite were used to solidify and immobilize these wastes. (author) 20 refs., 1 fig., 6 tabs.; e-mail: tellocc at urano.cdtn.br

Normal Limits of Electrocardiogram and Cut-Off Values for Left ...

African Journals Online (AJOL)

Gender difference exists in some cut-off values for LVH. This study defined the normal limits for electrocardiographic variables for young adult Nigerians. Racial factor should be taken into consideration in interpretation of ECG. Keywords: Normal limits, Electrocardiogram, Cut-off values, Left ventricular hypertrophy, Young ...

Bentonite reactivity in alkaline solutions: results of the Cyprus natural analogue project (CNAP)

International Nuclear Information System (INIS)

Alexander, W.R.; Milodowski, A.E.; Pitty, A.F.; Hardie, S.M.L.; Korkeakoski, P.; Norris, S.; Puigdomenech, I.; Sellin, P.; Rigas, M.

2012-01-01

Document available in extended abstract form only. Bentonite is one of the most safety-critical components of the engineered barrier system in the disposal concepts developed for many types of radioactive waste. Bentonite is used due to its favourable properties (including plasticity, swelling capacity, colloid filtration, low hydraulic conductivity, high retardation of key radionuclides) and its stability in relevant geological environments. However, bentonite is unstable under alkaline conditions and, due to the fact that cementitious materials react with groundwater to produce initial leachates with pH >13 (later falling to around pH 12.5), this has driven recent interest in low alkali cements, because the pH of the leachate is somewhat lower than standard OPC (Ordinary Portland Cement), lying around pH 10-11. It is hoped that this lower pH will reduce bentonite reaction, so allowing the use of low alkali cements in close proximity with bentonite. Assuring the long-term stability of bentonite in contact with such alkaline fluids under conditions representative of a deep geological repository requires complementary laboratory, modelling and in situ studies. In particular, to build a robust safety case, it is important to have supporting natural analogue data to confirm understanding - and validate models - of the likely long-term performance of bentonite. As a result of a review of the available literature and recent geological investigations by the authors, several sites in Cyprus were selected as particularly promising for this purpose. All alkaline groundwaters studied so far in Cyprus originate from ophiolite host rocks which are wide-spread across the island. The alkaline pH values (generally between pH 10 and 11, but a maximum of 12 has been observed) reported in the groundwaters are a product of the serpentinization of the ophiolites. The presence of bentonite and other clay-rich rocks in close proximity to the natural alkaline groundwaters permits the

Defining obesity cut-off points for migrant South Asians.

Directory of Open Access Journals (Sweden)

Laura J Gray

Full Text Available Body mass index (BMI and waist circumference (WC are used to define cardiovascular and type 2 diabetes risk. We aimed to derive appropriate BMI and WC obesity cut-off points in a migrant South Asian population.4688 White Europeans and 1333 South Asians resident in the UK aged 40-75 years inclusive were screened for type 2 diabetes. Principal components analysis was used to derive a glycaemia, lipid, and a blood pressure factor. Regression models for each factor, adjusted for age and stratified by sex, were used to identify BMI and WC cut-off points in South Asians that correspond to those defined for White Europeans.For South Asian males, derived BMI obesity cut-off points equivalent to 30.0 kg/m(2 in White Europeans were 22.6 kg/m(2 (95% Confidence Interval (95% CI 20.7 kg/m(2 to 24.5 kg/m(2 for the glycaemia factor, 26.0 kg/m(2 (95% CI 24.7 kg/m(2 to 27.3 kg/m(2 for the lipid factor, and 28.4 kg/m(2 (95% CI 26.5 kg/m(2 to 30.4 kg/m(2 for the blood pressure factor. For WC, derived cut-off points for South Asian males equivalent to 102 cm in White Europeans were 83.8 cm (95% CI 79.3 cm to 88.2 cm for the glycaemia factor, 91.4 cm (95% CI 86.9 cm to 95.8 cm for the lipid factor, and 99.3 cm (95% CI 93.3 cm to 105.2 cm for the blood pressure factor. Lower ethnicity cut-off points were seen for females for both BMI and WC.Substantially lower obesity cut-off points are needed in South Asians to detect an equivalent level of dysglycemia and dyslipidemia as observed in White Europeans. South Asian ethnicity could be considered as a similar level of risk as obesity (in White Europeans for the development of type 2 diabetes.

A Comparative Study of the Retentive Strengths of Commercial and Indigenously Developed Luting Cements using Both Lathe-cut and Clinically Simulated Specimens.

Science.gov (United States)

Mathew, Joe; Kurian, Byju P; Philip, Biju; Mohammed, Sunil; Menon, Preetha; Raj, Rajan S

2016-08-01

Superior adhesive strength in luting agents is of paramount significance in fixed partial denture success. In this in vitro study five cements were tested for retentive qualities, using both lathe-cut and hand-prepared specimens. A total of 104 freshly extracted tooth specimens were prepared. Seventy of them were lathe-cut and 30 specimens were hand-prepared to simulate clinical conditions. Five different cements were tested, which included a compomer, a composite, a zinc phosphate, and 2 glass-ionomer luting cements. Of the 5, 2 trial cements were indigenously developed by Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Trivandrum, India - a glass-ionomer cement (Chitra GIC) and a chemical-cure composite (Chitra CCC). All cements were compared within each group and between groups (lathe-prepared and hand-prepared). GC Fuji 1 (GC America) exhibited superior retentive strengths in both lathe-cut and hand-prepared specimens, whereas the compomer cement displayed the lowest values when tested. In lathe-cut specimens, statistical analysis showed no significant difference between GC Fuji 1 and indigenously developed Chitra CCC. Both Chitra CCC and GC Fuji 1 have comparable strengths in lathe-cut samples, making Chitra CCC a potential luting agent. Statistical analysis reveals that all cements, except GC Fuji 1, exhibited a significant decrease in strength due to the change in design uniformity. The chemical bonding of GC Fuji 1 proves to be quite strong irrespective of shape and precision of the tooth crown. The indigenously developed Chitra GIC and Chitra CCC showed promising results to be used as a potential luting agent.

PVD-Alumina Coatings on Cemented Carbide Cutting Tools: A Study About the Effect on Friction and Adhesion Mechanism

Directory of Open Access Journals (Sweden)

S.E. Cordes

2012-03-01

Full Text Available Crystalline PVD γ-alumina coatings are interesting for machining operations due to their outstanding characteristics, such as high hot hardness, high thermal stability and low tendency to adhesion. In the present work (Ti,AlN/γ-Al2O3-coatings are deposited on cemented carbide by means of MSIP. Objectives of this work are to study the effects of coating and cutting fluid regarding friction in tribological tests and to study the wear mechanisms and cutting performance of γ-Al2O3-based coated cemented carbide cutting tools in machining operations of austenitic stainless steels. Based on the remarkable properties of the coating system the performance of the cutting tools is increasing significantly.

Relationship between the optimum cut off frequency for Butter worth filter and lung-heart ratio in 99mTc myocardial SPECT

International Nuclear Information System (INIS)

Salihin Yusoff, M. N.; Zakaria, A.

2010-01-01

We investigated whether the lung-heart ratio parameter can be used to identify the optimum cut off frequency for Butter worth filter in 99m Tc myocardial SPECT imaging. Materials and Methods: This study involved a cardiac phantom system consisting of cardiac insert in which 1.10 cm cold defect was inserted into its myocardium wall and filled with 4.0 μCi/ml (0.148 MBq/ml) 99m Tc concentration. The cardiac insert was then put into a cylindrical tank which filled with six different 99m Tc concentrations as background. Thus, six target background concentrations ratios (T/B) were carried out. The lung-heart ratio was determined for every SPECT raw image obtained corresponding to each T/B. Then, 130 different combinations of filter parameters from Butter worth filter were utilized to reconstruct each SPECT raw image. The determination of count in myocardium, background, and defect regions of interest were performed for every reconstructed image. All the count values were then used to calculate contrast, signal-to-noise ratio, and defect size. Each criterion was graded (1 to 100) and then summed together to obtain total grade. The optimum cut off frequency for each lung-heart ratio was determined from the total grade. The relation between optimum cut off frequency for Butter worth filter and lung-heart ratio was established using linear regression. Results: There were good relationship between the optimum Butter worth cut off frequency and lung-heart ratio (R 2 = 0.864, p<0.01). The optimal cut off frequency correspond to the change in lung-heart ratio can be expressed by the equation: Optimum cut off frequency=0.715*lung-heart ratio + 0.227. Conclusion: This study suggests that the optimum cut off frequency for Butter worth filter should be determined by referring to lung-heart ratio in each patient study.

Development of thick wall welding and cutting tools for ITER

International Nuclear Information System (INIS)

Nakahira, Masataka; Takahashi, Hiroyuki; Akou, Kentaro; Koizumi, Koichi

1998-01-01

The Vacuum Vessel, which is a core component of International Thermonuclear Experimental Reactor (ITER), is required to be exchanged remotely in a case of accident such as superconducting coil failure. The in-vessel components such as blanket and divertor are planned to be exchanged or fixed. In these exchange or maintenance operations, the thick wall welding and cutting are inevitable and remote handling tools are necessary. The thick wall welding and cutting tools for blanket are under developing in the ITER R and D program. The design requirement is to weld or cut the stainless steel of 70 mm thickness in the narrow space. Tungsten inert gas (TIG) arc welding, plasma cutting and iodine laser welding/cutting are selected as primary option. Element welding and cutting tests, design of small tools to satisfy space requirement, test fabrication and performance tests were performed. This paper reports the tool design and overview of welding and cutting tests. (author)

Development of thick wall welding and cutting tools for ITER

Energy Technology Data Exchange (ETDEWEB)

Nakahira, Masataka; Takahashi, Hiroyuki; Akou, Kentaro; Koizumi, Koichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-04-01

The Vacuum Vessel, which is a core component of International Thermonuclear Experimental Reactor (ITER), is required to be exchanged remotely in a case of accident such as superconducting coil failure. The in-vessel components such as blanket and divertor are planned to be exchanged or fixed. In these exchange or maintenance operations, the thick wall welding and cutting are inevitable and remote handling tools are necessary. The thick wall welding and cutting tools for blanket are under developing in the ITER R and D program. The design requirement is to weld or cut the stainless steel of 70 mm thickness in the narrow space. Tungsten inert gas (TIG) arc welding, plasma cutting and iodine laser welding/cutting are selected as primary option. Element welding and cutting tests, design of small tools to satisfy space requirement, test fabrication and performance tests were performed. This paper reports the tool design and overview of welding and cutting tests. (author)

[Correlation analysis of cement leakage with volume ratio of intravertebral bone cement to vertebral body and vertebral body wall incompetence in percutaneous vertebroplasty for osteoporotic vertebral compression fractures].

Science.gov (United States)

Liang, De; Ye, Linqiang; Jiang, Xiaobing; Huang, Weiquan; Yao, Zhensong; Tang, Yongchao; Zhang, Shuncong; Jin, Daxiang

2014-11-01

To investigate the risk factors of cement leakage in percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fracture (OVCF). Between March 2011 and March 2012, 98 patients with single level OVCF were treated by PVP, and the clinical data were analyzed retrospectively. There were 13 males and 85 females, with a mean age of 77.2 years (range, 54-95 years). The mean disease duration was 43 days (range, 15-120 days), and the mean T score of bone mineral density (BMD) was -3.8 (range, -6.7- -2.5). Bilateral transpedicular approach was used in all the patients. The patients were divided into cement leakage group and no cement leakage group by occurrence of cement leakage based on postoperative CT. Single factor analysis was used to analyze the difference between 2 groups in T score of BMD, operative level, preoperative anterior compression degree of operative vertebrae, preoperative middle compression degree of operative vertebrae, preoperative sagittal Cobb angle of operative vertebrae, preoperative vertebral body wall incompetence, cement volume, and volume ratio of intravertebral bone cement to vertebral body. All relevant factors were introduced to logistic regression analysis to analyze the risk factors of cement leakage. All procedures were performed successfully. The mean operation time was 40 minutes (range, 30-50 minutes), and the mean volume ratio of intravertebral bone cement to vertebral body was 24.88% (range, 7.84%-38.99%). Back pain was alleviated significantly in all the patients postoperatively. All patients were followed up with a mean time of 8 months (range, 6-12 months). Cement leakage occurred in 49 patients. Single factor analysis showed that there were significant differences in the volume ratio of intravertebral bone cement to vertebral body and preoperative vertebral body wall incompetence between 2 groups (P 0.05). The logistic regression analysis showed that the volume ratio of intravertebral bone cement to vertebral body (P

Classifying post-stroke fatigue: Optimal cut-off on the Fatigue Assessment Scale.

Science.gov (United States)

Cumming, Toby B; Mead, Gillian

2017-12-01

Post-stroke fatigue is common and has debilitating effects on independence and quality of life. The Fatigue Assessment Scale (FAS) is a valid screening tool for fatigue after stroke, but there is no established cut-off. We sought to identify the optimal cut-off for classifying post-stroke fatigue on the FAS. In retrospective analysis of two independent datasets (the '2015' and '2007' studies), we evaluated the predictive validity of FAS score against a case definition of fatigue (the criterion standard). Area under the curve (AUC) and sensitivity and specificity at the optimal cut-off were established in the larger 2015 dataset (n=126), and then independently validated in the 2007 dataset (n=52). In the 2015 dataset, AUC was 0.78 (95% CI 0.70-0.86), with the optimal ≥24 cut-off giving a sensitivity of 0.82 and specificity of 0.66. The 2007 dataset had an AUC of 0.83 (95% CI 0.71-0.94), and applying the ≥24 cut-off gave a sensitivity of 0.84 and specificity of 0.67. Post-hoc analysis of the 2015 dataset revealed that using only the 3 most predictive FAS items together ('FAS-3') also yielded good validity: AUC 0.81 (95% CI 0.73-0.89), with sensitivity of 0.83 and specificity of 0.75 at the optimal ≥8 cut-off. We propose ≥24 as a cut-off for classifying post-stroke fatigue on the FAS. While further validation work is needed, this is a positive step towards a coherent approach to reporting fatigue prevalence using the FAS. Copyright © 2017 Elsevier Inc. All rights reserved.

Environmental sampling: Issues for the cut-off regime

International Nuclear Information System (INIS)

Fearey, B.L.

1995-01-01

The fissile material cut-off treaty (FMCT) initiative under the Conference on Disarmament mandate is envisioned to include certain aspects of environmental sampling and monitoring. One of the intents of this treaty is to bring certain non-NPT signatories (e.g., threshold states) under this treaty agreement along with the nuclear weapon states (NWSs). This paper provides a brief overview of some of the relevant issues that may be involved in the implementation and use of environmental monitoring for (1) verification of the cut-off regime declarations, (2) the detection of undeclared activities, and, (3) application in non-routine inspections. The intent is to provide backstopping information important for treaty negotiators. Specific issues addressed within this paper include signature sampling, differences in the proposed detection regime, potential signature integrators, specific examples and spoofing concerns. Many of these issues must be carefully considered and weighed in order to create a credibly verifiable inspection regime. Importantly, the cut-off treaty must enable nondiscriminatory implementation, while carefully assuring that nonproliferation treaty requirements are maintained (i.e., preventing unintentional release of critical weapons design information--potentially through environmental sampling and analysis)

The precision cutting control research of automotive stainless steel thin wall pipe

Directory of Open Access Journals (Sweden)

Jin Lihong

2015-01-01

Full Text Available Stainless steel thin-walled tube are widely used in automobile industry at present, but as a result of thin wall pipe is poor strength and poor rigidity,which lead to deformation, shaped differencer and other problems in the process, it is hard to ensure the processing quality of parts. This paper proposes a method of thin stainless steel thin wall pipe cutting process in vehicle, greatly improved the problems and technical difficulties in the traditional process, the main research is about the cutting system and the hydraulic fixture design, obtained under low cost circumstances, it can realize high precision stainless steel pipes, high degree of automation to automatic cutting,simplified operation steps at the same time, increased the applicability of the system, provided a kind of advanced stainless steel thin wall pipe cutting device for the small and medium-sized enterprises.

Explaining the use of attribute cut-off values in decision making by means of involvement

DEFF Research Database (Denmark)

Peschel, Anne O.; Grebitus, Carola; Colson, Gregory

2016-01-01

evidence on consumers’ heterogeneous use of attribute cut-offs with a unique focus on the relationship with consumer involvement, a key component in consumer choice theory. Behavioral data from an online choice experiment on beef steak employing shelf simulations are combined with questions defining...... a latent class model identifies several key consumer segments (e.g., a price sensitive group) based on their choice behavior and reveals that the relationship between involvement, cut-off use and cut-off violations is not uniform across consumer segments....... respondents’ attribute cut-off values and their validated Personal Involvement Inventory (PII). Evidence from the analysis indicates that consumers who are highly involved are more likely to exhibit attribute cut-off values and are less likely to violate their cut-off values. Further investigation using...

Axial and transverse tensile properties Zr-2.5Nb pressure tube off-cuts

International Nuclear Information System (INIS)

Shah, Priti K.; Dubey, J.S.; Shriwastaw, R.S.; Balakrishnan, K.S.; Anantharaman, S.; Chakravartty, J.K.

2011-01-01

Zr-2.5Nb alloys in cold worked and stress relieved (CWSR) condition serves as pressure boundary for hot coolant in Indian Pressurized Heavy Water Reactor (IPHWR). Due to both microstructural and crystallographic anisotropy, the mechanical properties in general and fracture behavior in particular are anisotropic for this material. To understand the anisotropic mechanical behavior of the Zr-2.5Nb pressure tubes of IPHWRs, tension tests were carried out on the RAPS-2 and KAPS-2 pressure tube off-cuts. Off-cuts are the small pieces cut from the two ends of a pressure tube before installing it into the PHWR. Miniature flat tensile specimens (without applying any flattening treatment to the pressure tube) of both longitudinal (or axial) and transverse orientation were fabricated from the off-cuts. Tension tests were carried out both at room temperature and 300 deg C. The transverse specimens showed higher strength and lower elongation than that of the axial ones. The back-end off-cuts showed higher strength compared to front-end off-cuts along axial direction whereas the same is not true for transverse direction specimens. One typical plot obtained in the testing of one of the off-cut is shown. The paper will discuss about the importance of the work carried out, test specimens, test method and results obtained in detail

A New Model for Optimal Mechanical and Thermal Performance of Cement-Based Partition Wall.

Science.gov (United States)

Huang, Shiping; Hu, Mengyu; Huang, Yonghui; Cui, Nannan; Wang, Weifeng

2018-04-17

The prefabricated cement-based partition wall has been widely used in assembled buildings because of its high manufacturing efficiency, high-quality surface, and simple and convenient construction process. In this paper, a general porous partition wall that is made from cement-based materials was proposed to meet the optimal mechanical and thermal performance during transportation, construction and its service life. The porosity of the proposed partition wall is formed by elliptic-cylinder-type cavities. The finite element method was used to investigate the mechanical and thermal behaviour, which shows that the proposed model has distinct advantages over the current partition wall that is used in the building industry. It is found that, by controlling the eccentricity of the elliptic-cylinder cavities, the proposed wall stiffness can be adjusted to respond to the imposed loads and to improve the thermal performance, which can be used for the optimum design. Finally, design guidance is provided to obtain the optimal mechanical and thermal performance. The proposed model could be used as a promising candidate for partition wall in the building industry.

A New Model for Optimal Mechanical and Thermal Performance of Cement-Based Partition Wall

Directory of Open Access Journals (Sweden)

Shiping Huang

2018-04-01

Full Text Available The prefabricated cement-based partition wall has been widely used in assembled buildings because of its high manufacturing efficiency, high-quality surface, and simple and convenient construction process. In this paper, a general porous partition wall that is made from cement-based materials was proposed to meet the optimal mechanical and thermal performance during transportation, construction and its service life. The porosity of the proposed partition wall is formed by elliptic-cylinder-type cavities. The finite element method was used to investigate the mechanical and thermal behaviour, which shows that the proposed model has distinct advantages over the current partition wall that is used in the building industry. It is found that, by controlling the eccentricity of the elliptic-cylinder cavities, the proposed wall stiffness can be adjusted to respond to the imposed loads and to improve the thermal performance, which can be used for the optimum design. Finally, design guidance is provided to obtain the optimal mechanical and thermal performance. The proposed model could be used as a promising candidate for partition wall in the building industry.

Accelerated hydration of high silica cements

International Nuclear Information System (INIS)

Walker, Colin; Yui, Mikazu

2012-01-01

Current Japanese designs for high level radioactive waste (HLW) repositories anticipate the use of both bentonite (buffer and backfill material) and cement based materials. Using hydrated Ordinary Portland Cement (OPC) as a grouting material is undesirable because the associated high pH buffer will have an undisputed detrimental effect on the performance of the bentonite buffer and backfill and of the host rock by changing its porosity. Instead, hydrated low pH cement (LopHC) grouting materials are being developed to provide a pH inferior or equal to 11 to reduce these detrimental effects. LopHC grouting materials use mixtures of superfine OPC (SOPC) clinker and silica fume (SF), and are referred as high silica cements (HSC). The focus of the present study was to identify the development of the unhydrated and hydrated mineral assemblage and the solution chemistry during the hydration of HSC. Since hydration experiments of cementitious materials are notably slow, a ball mill was used to accelerate hydration. This was done for two reasons. Firstly, to develop a method to rapidly hydrate cement based materials without the need for higher temperatures (which can alter the mineral assemblage), and secondly, to ensure that the end point of hydration was reached in a reasonable time frame and so to realize the final mineralogy and solution chemistry of hydrated HSC

Hemoglobin cut-off values in healthy Turkish infants

Institute of Scientific and Technical Information of China (English)

Ahmet Arvas; Emel Gür; DurmuşDoğan

2014-01-01

Background: Anemia is a widespread public health problem associated with an increased risk of morbidity and mortality. This study was undertaken to determine the cut-off value of hemoglobin for infant anemia. Methods: A cross-sectional retrospective study was carried out at well-baby clinics of a tertiary care hospital. A total of 1484 healthy infants aged between 4 to 24 months were included in the study. The relationship of hemoglobin (Hb) levels with mother age, birth weight, weight gain rate, feeding, and gender was evaluated. Results: The Hb levels were assessed in four age groups (4 months, 6 months, 9-12 months, and 15-24 months) and the cut-off values of Hb were determined. Hb cut-off values (5th percentile for age) were detected as 97 g/L and 93 g/L at 4 months and 6 months, respectively. In older infants, the 5th percentile was 90.5 g/L and 93.4 g/L at 9-12 months and 15-24 months, respectively. The two values were lower than the World Health Organization criteria for anemia, which could partly due to the lack of information on iron status in our population. However, this difference highlights the need for further studies on normal Hb levels in healthy infants in developing countries. Hb levels of females were higher in all age groups; however, a statistically significant difference was found in gender in only 6 month-old infants. No statistically significant difference was found among Hb levels, mother's age, birth weight, weight gain rate, and nutritional status. Conclusion: Hb cut-off values in infants should be re-evaluated and be compatible with growth and development of children in that community.

Natural analogue studies of bentonite reaction under hyperalkaline conditions. Overview of ongoing work at the Zambales ophiolite, Philippines

International Nuclear Information System (INIS)

Fujii, N.; Yanakawa, M.; Arcilla, C.A.; Pascua, C.; Namiki, K.; Sato, T.; Shikazono, N.; Alexander, W.R.

2011-01-01

Bentonite is one of the safety-critical components of the engineered barrier system for the disposal concepts developed for many types of radioactive waste. However, bentonite - especially the swelling clay component that contributes to its essential barrier functions - is unstable at high pH. To date, results from laboratory tests on bentonite degradation have been ambiguous as the reaction rates are so slow as to be difficult to observe. As such, a key goal in this project is to examine the reaction of natural bentonites in contact with natural hyperalkaline groundwaters to determine if any long-term alteration of the bentonite occurs. Ophiolites have been identified as sources of hyperalkaline groundwaters that can be considered natural analogues of the leachates produced by some cementitious materials in repositories for radioactive waste. At the Zambales ophiolite in the Philippines, widespread active serpentinisation results in hyperalkaline groundwaters with measured pH values of up to 11.7, falling into the range typical of low-alkali cement porewaters. These cements are presently being developed worldwide to minimise the geochemical perturbations which are expected to result from the use of OPC-based concretes (see Kamei et al., this conference, for details). In particular, it is hoped that the lower pH of the low-alkali cement leachates will reduce, or even avoid entirely, the potential degradation of the bentonite buffer which is expected at the higher pH levels (12.5 and above) common to OPC-based concretes. During recent field campaigns at two sites in the Zambales ophiolite (Mangatarem and Bigbiga), samples of bentonite and the associated hyperalkaline groundwaters have been collected by drilling and trenching. At Mangatarem, qualitative data from a 'fossil' (i.e. no groundwater is currently present) reaction zone indicates some alteration of the bentonite to zeolite, serpentine and CSH phases. Preliminary reaction path modelling suggests that the

Raised BMI cut-off for overweight in Greenland Inuit--a review.

Science.gov (United States)

Andersen, Stig; Fleischer Rex, Karsten; Noahsen, Paneeraq; Sørensen, Hans Christian Florian; Mulvad, Gert; Laurberg, Peter

2013-01-01

Obesity is associated with increased morbidity and premature death. Obesity rates have increased worldwide and the WHO recommends monitoring. A steep rise in body mass index (BMI), a measure of adiposity, was detected in Greenland from 1963 to 1998. Interestingly, the BMI starting point was in the overweight range. This is not conceivable in a disease-free, physically active, pre-western hunter population. This led us to reconsider the cut-off point for overweight among Inuit in Greenland. We found 3 different approaches to defining the cut-off point of high BMI in Inuit. First, the contribution to the height by the torso compared to the legs is relatively high. This causes relatively more kilograms per centimetre of height that increases the BMI by approximately 10% compared to Caucasian whites. Second, defining the cut-off by the upper 90-percentile of BMI from height and weight in healthy young Inuit surveyed in 1963 estimated the cut-off point to be around 10% higher compared to Caucasians. Third, if similar LDL-cholesterol and triglycerides are assumed for a certain BMI in Caucasians, the corresponding BMI in Inuit in both Greenland and Canada is around 10% higher. However, genetic admixture of Greenland Inuit and Caucasian Danes will influence this difference and hamper a clear distinction with time. Defining overweight according to the WHO cut-off of a BMI above 25 kg/m(2) in Greenland Inuit may overestimate the number of individuals with elevated BMI.

Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications

International Nuclear Information System (INIS)

Boroujeni, Nariman Mansoori; Zhou, Huan; Luchini, Timothy J.F.; Bhaduri, Sarit B.

2013-01-01

In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO 4 ) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09 ± 1.85 MPa to 21.56 ± 2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials. - Highlights: • A monetite bone cement for orthopedic applications is reported. • Incorporation of MWCNTs into monetite bone cement is discussed. • Surface functionalized MWCNTs can improve the mechanical strength of monetite cement. • MWCNTs have no impacts on the cytocompatibility of monetite cements

Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications

Energy Technology Data Exchange (ETDEWEB)

Boroujeni, Nariman Mansoori [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Zhou, Huan, E-mail: Huan.Zhou@Rockets.utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Luchini, Timothy J.F. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

2013-10-15

In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO{sub 4}) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09 ± 1.85 MPa to 21.56 ± 2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials. - Highlights: • A monetite bone cement for orthopedic applications is reported. • Incorporation of MWCNTs into monetite bone cement is discussed. • Surface functionalized MWCNTs can improve the mechanical strength of monetite cement. • MWCNTs have no impacts on the cytocompatibility of monetite cements.

Surface effect theory in binary alloys: surfaces with cut-off

International Nuclear Information System (INIS)

Kumar, V.; Silva, C.E.T.G. da; Moran-Lopez, J.L.

1981-01-01

A surface effect theory in binary alloys which ore ordered with surfaces with cut-off is presented. This theory is based in a model of pair interaction between first neighbours and includes long and short range effects. The (120) surface with sup(-) (110) monoatomic cut-off and terrace in the (110) planes of an alloy with body centered cubic structure is presented as example. Results for the concentrations in all the different surface sites are given. (L.C.) [pt

Study on evolution of disposal environment due to alteration of cement. Commission work report

International Nuclear Information System (INIS)

Iriya, K.; Kubo, H.; Kato, T.; Fujita, H.

2001-02-01

The study shows effects on performance of the engineered and geological barriers due to alteration of cement including low alkalinity cement. Alteration test of bentonite and crystalline rock was carried out by low alkalinity cement pore water. Leaching of super plasticizer was investigated modeled for the latest period of alteration of cement. Planning a experiment for corrosion of re-bar in low alkalinity cement was carried out. Application of the cement for shotcrete was investigated. The results described below are obtained. 1. Almost of montmorillonite was solved in Na-K-Ca mixed solution. No alteration was observed in low alkalinity cement. The similar results were obtained for crystalline rock. 2. It is noted that main part of super plasticizer wasn't leachate even in the latest period of leaching of cement. Increment of leaching of super plasticizer wasn't observed corresponding to leaching of cement hydrates. 3. Accelerating test for corrosion of re-bar in low alkalinity cement was proposed. 4. It was demonstrated that low alkalinity cement was applicable for shotcrete. 5. pH of pore water of cement with highly pozzolanic materials isn't significantly decreased in high temperature. 6. Predictable alteration of barriers due to alteration of cement were pointed out including interaction of bentonite and rock. (author)

Strength and Compaction Analysis of Sand-Bentonite-Coal Ash Mixes

Science.gov (United States)

Sobti, Jaskiran; Singh, Sanjay Kumar

2017-08-01

This paper deals with the strength and compaction characteristics of sand-bentonite-coal ash mixes prepared by varying percentages of sand, bentonite and coal ash to be used in cutoff walls and as a liner or cover material in landfills. The maximum dry density (MDD) and optimum moisture content (OMC) of sand-bentonite mixes and sand-bentonite-coal ash mixes were determined by conducting the standard proctor test. Also, the strength and stiffness characteristics of soil mixes were furnished using unconfined compressive strength test. The results of the study reveal influence of varying percentages of coal ash and bentonite on the compaction characteristics of the sand-bentonite-coal ash mixes. Also, validation of a statistical analysis of the correlations between maximum dry density (MDD), optimum moisture content (OMC) and Specific Gravity (G) was done using the experimental results. The experimental results obtained for sand-bentonite, sand-bentonite-ash and coal ash-bentonite mixes very well satisfied the statistical relations between MDD, OMC and G with a maximum error in the estimate of MDD being within ±1 kN/m3. The coefficient of determination (R2) ranged from 0.95 to 0.967 in case of sand-bentonite-ash mixes. However, for sand-bentonite mixes, the R2 values are low and varied from 0.48 to 0.56.

Cut-off frequencies of circumferential horizontal shear waves in various functionally graded cylinder shells.

Science.gov (United States)

Shen, Xiaoqin; Ren, Dawei; Cao, Xiaoshan; Wang, Ji

2018-03-01

In this study, cut-off frequencies of the circumferential SH waves in functionally graded piezoelectric-piezomagnetic material (FGPPM) cylinder shells with traction free, electrical and magnetic open boundary conditions are investigated analytically. The Wentzel-Kramers-Brillouin (WKB) method is employed for solving differential equations with variable coefficients for general cases. For comparison, Bessel functions and Kummer functions are used for solving cut-off frequency problems in homogenous and ideal FGPPM cylinder shells. It is shown that the WKB solution for the cut-off frequencies has good precise. The set of cut-off frequencies is a series of approximate arithmetic progressions, for which the difference is a function of the density and the effective elastic parameter. The relationship between the difference and the gradient coefficient is described. These results provide theoretical guidance for the non-destructive evaluation of curved shells based on the cut-off frequencies. Copyright © 2017 Elsevier B.V. All rights reserved.

Human papillomavirus testing in primary cervical screening and the cut-off level for hybrid capture 2 tests

DEFF Research Database (Denmark)

Rebolj, Matejka; Bonde, Jesper; Njor, Sisse Helle

2011-01-01

To determine the trade-off between the sensitivity and the specificity for high grade cervical intraepithelial neoplasia at hybrid capture 2 cut-off values above the standard = 1 relative light units/cut-off level (rlu/co).......To determine the trade-off between the sensitivity and the specificity for high grade cervical intraepithelial neoplasia at hybrid capture 2 cut-off values above the standard = 1 relative light units/cut-off level (rlu/co)....

Hydrothermal stability of bentonite-based buffer materials

International Nuclear Information System (INIS)

Johnston, R.M.; Miller, H.G.

1985-02-01

The reactions expected in bentonite-based buffer materials under conditions typical of a nuclear fuel waste disposal include mineral transformations (e.g. smectite to illite; smectite to zeolite) and a range of low-temperature cementation reactions. The probable extent and significance of these reactions are reviewed, and other reactions involving proposed filler sands are also examined briefly. The effects of mineral transformations on buffer performance will be insignificant if disposal vault temperatures do not exceed 100-120 degrees C and pH remains in the range 4 to 8. At pH > 9, zeolitization and silica dissolution may occur and buffer stability cannot be assured. The effects of cementation reactions may be significant, but are difficult to predict and require further investigation

Optimised cut-off function for Tersoff-like potentials for a BN nanosheet: a molecular dynamics study

International Nuclear Information System (INIS)

Kumar, Rajesh; Rajasekaran, G; Parashar, Avinash

2016-01-01

In this article, molecular dynamics based simulations were carried out to study the tensile behaviour of boron nitride nanosheets (BNNSs). Four different sets of Tersoff potential parameters were used in the simulations for estimating the interatomic interactions between boron and nitrogen atoms. Modifications were incorporated in the Tersoff cut-off function to improve the accuracy of results with respect to fracture stress, fracture strain and Young’s modulus. In this study, the original cut-off function was optimised in such a way that small and large cut-off distances were made equal, and hence a single cut-off distance was used with all sets of Tersoff potential parameters. The single value of cut-off distance for the Tersoff potential was chosen after analysing the potential energy and bond forces experienced by boron and nitrogen atoms subjected to bond stretching. The simulations performed with the optimised cut-off function help in identifying the Tersoff potential parameters that reproduce the experimentally evaluated mechanical behaviour of BNNSs. (paper)

Study on evolution of disposal environment due to alteration of cement. Summary report. Commission work report

International Nuclear Information System (INIS)

Iriya, K.; Kubo, H.; Kato, T.; Fujita, H.

2001-02-01

The study shows effects on performance of the engineered and geological barriers due to alteration of cement including low alkalinity cement. Alteration test of bentonite and crystalline rock was carried out by low alkalinity cement pore water. Leaching of super plasticizer was investigated modeled for the latest period of alteration of cement. Planning a experiment for corrosion of re-bar in low alkalinity cement was carried out. Application of the cement for shotcrete was investigated. The results described below are obtained. 1. Almost of montmorillonite was solved in Na-K-Ca mixed solution. No alteration was observed in low alkalinity cement. The similar results were obtained for crystalline rock. 2. It is noted that main part of super plasticizer wasn't leachated even in the latest period of leaching of cement. Increment of leaching of super plasticizer wasn't observed corresponding to leaching of cement hydrates. 3. Accelerating test for corrosion of re-bar in low alkalinity cement was proposed. 4. It was demonstrated that low alkalinity cement was applicable for shotcrete. 5. pH of pore water of cement with highly pozzolanic materials isn't significantly decreased in high temperature. 6. Predictable alteration of barriers due to alteration of cement were pointed out including interaction of bentonite and rock. (author)

The influence of organic cement additives on radionuclide mobility. A literature survey

International Nuclear Information System (INIS)

Hakanen, M.; Ervanne, H.

2006-02-01

This review evaluates the influence of organic cement additives on radionuclide mobility. The work outlines evaluations under cement conditions where report drafts were available, and an evaluation under groundwater conditions (non-cement conditions) based on the chemical structures of the main components in polyelectrolyte additives and on recent results of metal-humic bounding. Literature of effects of plasticizers on copper and bentonite are reviewed. (orig.)

Studies of the setting behavior of cement suspensions

International Nuclear Information System (INIS)

Rudolph, G.; Luo, S.; Vejmelka, P.; Koester, R.

1983-10-01

The design of process for cementation of radioactive waste solutions is determined not only by the quality of the final product but also by the behavior of the cement grout before and during setting. For these reasons quantitative investigations were performed on the characteristics of the cement suspensions considered for solidification of intermediate-level liquid wastes which are composed mainly of cement, bentonite, simulated waste solution, and water. Particular interest was given to the differences in behavior of the various types of cement. The parameters investigated include viscosity, bleeding, volume change during setting, influence of compacting by vibration, time of setting, heat of hydration. At the end of the report the merits and drawbacks of the different cements are tabulated. These data may serve as a decision aid in selecting an appropriate type of cement

Systematic review of the evidence for Trails B cut-off scores in assessing fitness-to-drive.

Science.gov (United States)

Roy, Mononita; Molnar, Frank

2013-01-01

Fitness-to-drive guidelines recommend employing the Trail Making B Test (a.k.a. Trails B), but do not provide guidance regarding cut-off scores. There is ongoing debate regarding the optimal cut-off score on the Trails B test. The objective of this study was to address this controversy by systematically reviewing the evidence for specific Trails B cut-off scores (e.g., cut-offs in both time to completion and number of errors) with respect to fitness-to-drive. Systematic review of all prospective cohort, retrospective cohort, case-control, correlation, and cross-sectional studies reporting the ability of the Trails B to predict driving safety that were published in English-language, peer-reviewed journals. Forty-seven articles were reviewed. None of the articles justified sample sizes via formal calculations. Cut-off scores reported based on research include: 90 seconds, 133 seconds, 147 seconds, 180 seconds, and Trails B cut-offs of 3 minutes or 3 errors (the '3 or 3 rule'). Major methodological limitations of this body of research were uncovered including (1) lack of justification of sample size leaving studies open to Type II error (i.e., false negative findings), and (2) excessive focus on associations rather than clinically useful cut-off scores.

Raised BMI cut-off for overweight in Greenland Inuit – a review

Science.gov (United States)

Andersen, Stig; Fleischer Rex, Karsten; Noahsen, Paneeraq; Sørensen, Hans Christian Florian; Mulvad, Gert; Laurberg, Peter

2013-01-01

Background Obesity is associated with increased morbidity and premature death. Obesity rates have increased worldwide and the WHO recommends monitoring. A steep rise in body mass index (BMI), a measure of adiposity, was detected in Greenland from 1963 to 1998. Interestingly, the BMI starting point was in the overweight range. This is not conceivable in a disease-free, physically active, pre-western hunter population. Objective This led us to reconsider the cut-off point for overweight among Inuit in Greenland. Design and findings We found 3 different approaches to defining the cut-off point of high BMI in Inuit. First, the contribution to the height by the torso compared to the legs is relatively high. This causes relatively more kilograms per centimetre of height that increases the BMI by approximately 10% compared to Caucasian whites. Second, defining the cut-off by the upper 90-percentile of BMI from height and weight in healthy young Inuit surveyed in 1963 estimated the cut-off point to be around 10% higher compared to Caucasians. Third, if similar LDL-cholesterol and triglycerides are assumed for a certain BMI in Caucasians, the corresponding BMI in Inuit in both Greenland and Canada is around 10% higher. However, genetic admixture of Greenland Inuit and Caucasian Danes will influence this difference and hamper a clear distinction with time. Conclusion Defining overweight according to the WHO cut-off of a BMI above 25 kg/m2 in Greenland Inuit may overestimate the number of individuals with elevated BMI. PMID:23986904

Raised BMI cut-off for overweight in Greenland Inuit – a review

Directory of Open Access Journals (Sweden)

Stig Andersen

2013-08-01

Full Text Available Background. Obesity is associated with increased morbidity and premature death. Obesity rates have increased worldwide and the WHO recommends monitoring. A steep rise in body mass index (BMI, a measure of adiposity, was detected in Greenland from 1963 to 1998. Interestingly, the BMI starting point was in the overweight range. This is not conceivable in a disease-free, physically active, pre-western hunter population. Objective. This led us to reconsider the cut-off point for overweight among Inuit in Greenland. Design and findings. We found 3 different approaches to defining the cut-off point of high BMI in Inuit. First, the contribution to the height by the torso compared to the legs is relatively high. This causes relatively more kilograms per centimetre of height that increases the BMI by approximately 10% compared to Caucasian whites. Second, defining the cut-off by the upper 90-percentile of BMI from height and weight in healthy young Inuit surveyed in 1963 estimated the cut-off point to be around 10% higher compared to Caucasians. Third, if similar LDL-cholesterol and triglycerides are assumed for a certain BMI in Caucasians, the corresponding BMI in Inuit in both Greenland and Canada is around 10% higher. However, genetic admixture of Greenland Inuit and Caucasian Danes will influence this difference and hamper a clear distinction with time. Conclusion. Defining overweight according to the WHO cut-off of a BMI above 25 kg/m2 in Greenland Inuit may overestimate the number of individuals with elevated BMI.

Azimuth cut-off model for significant wave height investigation along coastal water of Kuala Terengganu, Malaysia

Science.gov (United States)

Marghany, Maged; Ibrahim, Zelina; Van Genderen, Johan

2002-11-01

The present work is used to operationalize the azimuth cut-off concept in the study of significant wave height. Three ERS-1 images have been used along the coastal waters of Terengganu, Malaysia. The quasi-linear transform was applied to map the SAR wave spectra into real ocean wave spectra. The azimuth cut-off was then used to model the significant wave height. The results show that azimuth cut-off varied with the different period of the ERS-1 images. This is because of the fact that the azimuth cut-off is a function of wind speed and significant wave height. It is of interest to find that the significant wave height modeled from azimuth cut-off is in good relation with ground wave conditions. It can be concluded that ERS-1 can be used as a monitoring tool in detecting the significant wave height variation. The azimuth cut-off can be used to model the significant wave height. This means that the quasi-linear transform could be a good application to significant wave height variation during different seasons.

Development and application of new composite grouting material for sealing groundwater inflow and reinforcing wall rock in deep mine.

Science.gov (United States)

Jinpeng, Zhang; Limin, Liu; Futao, Zhang; Junzhi, Cao

2018-04-04

With cement, bentonite, water glass, J85 accelerator, retarder and water as raw materials, a new composite grouting material used to seal groundwater inflow and reinforce wall rock in deep fractured rock mass was developed in this paper. Based on the reaction mechanism of raw material, the pumpable time, stone rate, initial setting time, plastic strength and unconfined compressive strength of multi-group proportion grouts were tested by orthogonal experiment. Then, the optimum proportion of composite grouting material was selected and applied to the grouting engineering for sealing groundwater inflow and reinforcing wall rock in mine shaft lining. The results show the mixing proportion of the maximum pumpable time, maximum stone rate and minimum initial setting time of grout are A K4 B K1 C K4 D K2 , A K3 B K1 C K1 D K4 and A K3 B K3 C K4 D K1 , respectively. The mixing proportion of the maximum plastic strength and unconfined compressive strength of grouts concretion bodies are A K1 B K1 C K1 D K3 and A K1 B K1 C K1 D K1 , respectively. Balanced the above 5 indicators overall and determined the optimum proportion of grouts: bentonite-cement ratio of 1.0, water-solid ratio of 3.5, accelerator content of 2.9% and retarder content of 1.45%. This new composite grouting material had good effect on the grouting engineering for sealing groundwater inflow and reinforcing wall rock in deep fractured rock mass.

Development of the cutting machine for the biological shield wall

International Nuclear Information System (INIS)

Yokota, Mitsuo; Hasegawa, Tetsuo; Kohyama, Kazunori.

1987-01-01

22 years have passed since the first commercial nuclear power plant operation in Japan. At present, there were 33 commercial nuclear power plants in operation, supplying about 25 percent of total electricity. Some of them are going to be terminated in the near future and enter into the decommissioning stage. Therefore, it is now necessary to developed decommissioning technologies, including dismantling techniques of these power plants. The development of a concrete cutting machine is one of the most important items applicable to dismantling biological shield walls of the plants. This paper describes the outline of the cutting machine developed for the biological shield wall demolition of the Japan Power Demonstration Reactor (JPDR) including actual decommissioning works tested. (author)

CHARACTERIZATION OF BENTONITE FOR ENGINEERED BARRIER SYSTEMS IN RADIOACTIVE WASTE DISPOSAL SITES

Directory of Open Access Journals (Sweden)

Dubravko Domitrović

2012-07-01

Full Text Available Engineered barrier systems are used in radioactive waste disposal sites in order to provide better protection of humans and the environment from the potential hazards associated with the radioactive waste disposal. The engineered barrier systems usually contain cement or clay (bentonite because of their isolation properties and long term performance. Quality control tests of clays are the same for all engineering barrier systems. Differences may arise in the required criteria to be met due for different application. Prescribed clay properties depend also on the type of host rocks. This article presents radioactive waste management based on best international practice. Standard quality control procedures for bentonite used as a sealing barrier in radioactive waste disposal sites are described as some personal experiences and results of the index tests (free swelling index, water adsorption capacity, plasticity limits and hydraulic permeability of bentonite (the paper is published in Croatian.

Age-adjusted high-sensitivity troponin T cut-off value for risk stratification of pulmonary embolism.

Science.gov (United States)

Kaeberich, Anja; Seeber, Valerie; Jiménez, David; Kostrubiec, Maciej; Dellas, Claudia; Hasenfuß, Gerd; Giannitsis, Evangelos; Pruszczyk, Piotr; Konstantinides, Stavros; Lankeit, Mareike

2015-05-01

High-sensitivity troponin T (hsTnT) helps in identifying pulmonary embolism patients at low risk of an adverse outcome. In 682 normotensive pulmonary embolism patients we investigate whether an optimised hsTnT cut-off value and adjustment for age improve the identification of patients at elevated risk. Overall, 25 (3.7%) patients had an adverse 30-day outcome. The established hsTnT cut-off value of 14 pg·mL(-1) retained its high prognostic value (OR (95% CI) 16.64 (2.24-123.74); p=0.006) compared with the cut-off value of 33 pg·mL(-1) calculated by receiver operating characteristic analysis (7.14 (2.64-19.26); pvalue of 45 pg·mL(-1) but not the established cut-off value of 14 pg·mL(-1) predicted an adverse outcome. An age-adjusted hsTnT cut-off value (≥14 pg·mL(-1) for patients aged risk (12.4% adverse outcome). Risk assessment of normotensive pulmonary embolism patients was improved by the introduction of an age-adjusted hsTnT cut-off value. A three-step approach helped identify patients at higher risk of an adverse outcome who might benefit from advanced therapy. Copyright ©ERS 2015.

Determination of a saliva cotinine cut-off to distinguish pregnant smokers from pregnant non-smokers

DEFF Research Database (Denmark)

Hegaard, Hanne K; Kjaergaard, Hanne; Møller, Lars F

2007-01-01

Objective validation of smoking status is necessary. Earlier studies have used saliva cotinine concentrations between 14.2 and 30 ng/ml as cut-off values to distinguish pregnant smokers from non-smokers. However, these cut-offs derive from studies including men and non-pregnant women....... This constitutes a problem, as recent studies have reported an accelerated metabolism in pregnant smokers. The aim of this study was to determine the optimum cut-off cotinine level distinguishing pregnant smokers from pregnant non-smokers....

On the use of bentonite clays of Sharshar section on Gulizindan horizon (Middle Eocene) for wines Lightening

International Nuclear Information System (INIS)

Kariev, A.R.; Jamalova, A.A.; Babaeva, V.S.; Yunusov, M.Yu.

1993-01-01

Gulizindan bentonite clay of Sharshar cuts period as on chemical-mineralogical structure and on technological and sorption properties do not differ from Georgia askanit clay. In the future it will allow at clearing wines of the republic industry instead of askanits to use a local bentonite

Treatment of Petroleum Drill Cuttings Using Stabilization/Solidification Method by Cement and Modified Clay Mixes

Directory of Open Access Journals (Sweden)

Soroush Ghasemi

2017-04-01

Full Text Available High organic content in petroleum drill cuttings is a substantial obstacle which hinders cement hydration and subsequently decreases the clean-up efficiency of the stabilization/solidification (S/S process. In this study, a modified clayey soil (montmorillonite with low to moderate polarity was used as an additive to cement. Because of its high adsorption capacity, the clay is capable of mitigating the destructive role of organic materials and preventing their interference with the hydration process. Mixes containing different ratios of cement, waste and modified clay were prepared and tested for their mechanical and chemical characteristics. Total petroleum hydrocarbons (TPH and Pb content of the samples were analyzed as well. For this purpose, the mixes were subjected to unconfined compressive strength (UCS and toxicity characteristic leaching procedure (TCLP tests. The results indicated that the specimens with 28-day curing time at a cement/waste ratio of 25% or higher (w/w and 10% modified clay (w/w met the Environmental Protection Agency (EPA criterion for compressive strength. Moreover, a reduction of 94% in the leaching of TPH was observed with the specimens undergoing the TCLP with a cement/waste ratio of 30% (w/w and a clay/waste ratio of 30% (w/w. Finally, the specimens with 30% cement/waste and 10% clay/waste ratios showed the least concentration (6.14% of leached Pb.

76 FR 33161 - Installation and Use of Engine Cut-off Switches on Recreational Vessels

Science.gov (United States)

2011-06-08

... ``Proposed Rule'' and insert ``USCG-2009-0206'' in the ``Keyword'' box. Click ``Search,'' then click on the... ``read comments'' box, which will then become highlighted in blue. In the ``Keyword'' box, insert ``USCG... add definitions that describe the terms ``engine cut-off switch link,'' ``engine cut- off switch...

Effect of the cut off frequency on rough point and flat surface contacts

International Nuclear Information System (INIS)

Meng, Fan Ming

2012-01-01

In the past years, contact between two bodies has been studied from various ways that do not consider the cut off frequency effect on the contact mechanism. This paper reports the correlation between rough point contact and flat surface contact at different cut off frequencies of filter. The similarity and difference between the two types of contact mechanisms are presented for materials with linear or elastic perfectly plastic deformation. The conjugate gradient method (CGM) is used for analysing the rough point contact, while the rough flat surface contact is studied with an improved CGM in which the influence coefficient for the elastic deformation of the rough flat surface is obtained with finite element method. Numerical results show that for the above two types of contacts, their von Mises stress and maximum shear stress are greatly affected by the cut-off frequency of a high pass filter. Moreover, a decrease in the cut-off frequency leads to an increase in the contact area and a decrease in the approach for the rough flat surface contact, while the opposite variations is for the point contact between rough bodies with the small radii

Enhanced CT perfusion cut-off sign in midgut volvulus

International Nuclear Information System (INIS)

Henesch, Stephen M.; Jaramillo, Diego M.; Nance, Michael L.

2006-01-01

We present a case of malrotation with midgut volvulus in an infant in which we discovered a unique CT sign called the perfusion cut-off sign. We hope this case will help establish this crucial diagnosis in other cases. (orig.)

Enhanced CT perfusion cut-off sign in midgut volvulus

Energy Technology Data Exchange (ETDEWEB)

Henesch, Stephen M.; Jaramillo, Diego M. [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Nance, Michael L. [Children' s Hospital of Philadelphia, Department of Surgery, Philadelphia, PA (United States)

2006-04-15

We present a case of malrotation with midgut volvulus in an infant in which we discovered a unique CT sign called the perfusion cut-off sign. We hope this case will help establish this crucial diagnosis in other cases. (orig.)

Can semiquantitative measurements of SUVmax and cut-off values differentiate colorectal malignant from benign lessions?

DEFF Research Database (Denmark)

Nguyen, Tram; Hess, Søren; Petersen, Henrik

2017-01-01

, which also precludes a clinically significant cut-off value. The same applies to SUVpeak and SUVmean while TLG measures may be more indicative. CONCLUSION: Semi-quantitative measurements of SUVmax and cut-off values proved inadequate for differentiating colorectal malignancies from benign findings...

Epidemiological cut-off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol.

Science.gov (United States)

Smith, P; Endris, R; Kronvall, G; Thomas, V; Verner-Jeffreys, D; Wilhelm, C; Dalsgaard, I

2016-02-01

Epidemiological cut-off values were developed for application to antibiotic susceptibility data for Flavobacterium psychrophilum generated by standard CLSI test protocols. The MIC values for ten antibiotic agents against Flavobacterium psychrophilum were determined in two laboratories. For five antibiotics, the data sets were of sufficient quality and quantity to allow the setting of valid epidemiological cut-off values. For these agents, the cut-off values, calculated by the application of the statistically based normalized resistance interpretation method, were ≤16 mg L(-1) for erythromycin, ≤2 mg L(-1) for florfenicol, ≤0.025 mg L(-1) for oxolinic acid (OXO), ≤0.125 mg L(-1) for oxytetracycline and ≤20 (1/19) mg L(-1) for trimethoprim/sulphamethoxazole. For ampicillin and amoxicillin, the majority of putative wild-type observations were 'off scale', and therefore, statistically valid cut-off values could not be calculated. For ormetoprim/sulphadimethoxine, the data were excessively diverse and a valid cut-off could not be determined. For flumequine, the putative wild-type data were extremely skewed, and for enrofloxacin, there was inadequate separation in the MIC values for putative wild-type and non-wild-type strains. It is argued that the adoption of OXO as a class representative for the quinolone group would be a valid method of determining susceptibilities to these agents. © 2014 John Wiley & Sons Ltd.

BENTONITE PROCESSING

Directory of Open Access Journals (Sweden)

Anamarija Kutlić

2012-07-01

Full Text Available Bentonite has vide variety of uses. Special use of bentonite, where its absorbing properties are employed to provide water-tight sealing is for an underground repository in granites In this paper, bentonite processing and beneficiation are described.

Influence of Different Cut-Off Values on the Diagnosis of Mild Cognitive Impairment in Parkinson's Disease

Directory of Open Access Journals (Sweden)

Inga Liepelt-Scarfone

2011-01-01

Full Text Available Comparable to Alzheimer's disease, mild cognitive impairment in Parkinson's disease (PD-MCI is associated with an increased risk for dementia. However different definitions of PD-MCI may have varying predictive accuracy for dementia. In a cohort of 101 nondemented Parkinson patients who underwent neuropsychological testing, the frequency of PD-MCI subjects and PD-MCI subtypes (i.e., amnestic/nonamnestic was determined by use of varying healthy population-based cut-off values. We also investigated the association between defined PD-MCI groups and ADL scales. Varying cut-off values for the definition of PD-MCI were found to affect frequency of PD-MCI subjects (9.9%–92.1% and, maybe more important, lead to a “shift” of proportion of detected PD-MCI subtypes especially within the amnestic single-domain subtype. Models using a strict cut-off value were significantly associated with lower ADL scores. Thus, the use of defined cut-off values for the definition of PD-MCI is highly relevant for comparison purposes. Strict cut-off values may have a higher predictive value for dementia.

Equilibrium properties of blackbody radiation with an ultraviolet energy cut-off

Science.gov (United States)

Mishra, Dheeraj Kumar; Chandra, Nitin; Vaibhav, Vinay

2017-10-01

We study various equilibrium thermodynamic properties of blackbody radiation (i.e. a photon gas) with an ultraviolet energy cut-off. We find that the energy density, specific heat etc. follow usual acoustic phonon dynamics as have been well studied by Debye. Other thermodynamic quantities like pressure, entropy etc. have also been calculated. The usual Stefan-Boltzmann law gets modified. We observe that the values of the thermodynamic quantities with the energy cut-off is lower than the corresponding values in the theory without any such scale. The phase-space measure is also expected to get modified for an exotic spacetime appearing at Planck scale, which in turn leads to the modification of Planck energy density distribution and the Wien's displacement law. We found that the non-perturbative nature of the thermodynamic quantities in the SR limit (for both unmodified and modified cases), due to nonanalyticity of the leading term, is a general feature of the theory accompanied with an ultraviolet energy cut-off. We have also discussed the possible modification in the case of Big Bang and the Stellar objects and have suggested a table top experiment for verification in effective low energy case.

Lactate clearance cut off for early mortality prediction in adult sepsis and septic shock patients

Science.gov (United States)

Sinto, R.; Widodo, D.; Pohan, H. T.

2018-03-01

Previous lactate clearance cut off for early mortality prediction in sepsis and septic shock patient was determined by consensus from small sample size-study. We investigated the best lactate clearance cut off and its ability to predict early mortality in sepsis and septic shock patients. This cohort study was conducted in Intensive Care Unit of CiptoMangunkusumo Hospital in 2013. Patients’ lactate clearance and eight other resuscitationendpoints were recorded, and theoutcome was observed during the first 120 hours. The clearance cut off was determined using receiver operating characteristic (ROC) analysis, and its ability was investigated with Cox’s proportional hazard regression analysis using other resuscitation endpoints as confounders. Total of 268 subjects was included, of whom 70 (26.11%) subjects died within the first 120 hours. The area under ROC of lactate clearance to predict early mortality was 0.78 (95% % confidence interval [CI] 0.71-0.84) with best cut off was <7.5% (sensitivity and specificity 88.99% and 81.4% respectively). Compared with group achieving lactate clearance target, group not achieving lactate clearance target had to increase early mortality risk (adjusted hazard ratio 13.42; 95%CI 7.19-25.07). In conclusion, the best lactate clearance cut off as anearly mortality predictor in sepsis and septic shock patients is 7.5%.

BANKRUPTCY PREDICTION MODEL WITH ZETAc OPTIMAL CUT-OFF SCORE TO CORRECT TYPE I ERRORS

Directory of Open Access Journals (Sweden)

Mohamad Iwan

2005-06-01

This research has successfully attained the following results: (1 type I error is in fact 59,83 times more costly compared to type II error, (2 22 ratios distinguish between bankrupt and non-bankrupt groups, (3 2 financial ratios proved to be effective in predicting bankruptcy, (4 prediction using ZETAc optimal cut-off score predicts more companies filing for bankruptcy within one year compared to prediction using Hair et al. optimum cutting score, (5 Although prediction using Hair et al. optimum cutting score is more accurate, prediction using ZETAc optimal cut-off score proved to be able to minimize cost incurred from classification errors.

Determination of a saliva cotinine cut-off to distinguish pregnant smokers from pregnant non-smokers

DEFF Research Database (Denmark)

Hegaard, Hanne K; Kjaergaard, Hanne; Møller, Lars F

2007-01-01

Objective validation of smoking status is necessary. Earlier studies have used saliva cotinine concentrations between 14.2 and 30 ng/ml as cut-off values to distinguish pregnant smokers from non-smokers. However, these cut-offs derive from studies including men and non-pregnant women. This consti...

Study on tribological behavior and cutting performance of CVD diamond and DLC films on Co-cemented tungsten carbide substrates

International Nuclear Information System (INIS)

Zhang Dongcan; Shen Bin; Sun Fanghong

2010-01-01

The tribological behaviors of diamond and diamond-like carbon (DLC) films play a major role on their machining and mechanical applications. In this study, diamond and diamond-like carbon (DLC) films are deposited on the cobalt cemented tungsten carbide (WC-Co) substrate respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode, and their friction properties are evaluated on a reciprocating ball-on-plate tribometer with counterfaces of silicon nitride (Si 3 N 4 ) ceramic, cemented tungsten carbide (WC) and ball-bearing steel materials, under the ambient air without lubricating condition. Moreover, to evaluate their cutting performance, comparative turning tests are conducted using the uncoated WC-Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The as-deposited HFCVD diamond and DLC films are characterized with energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Raman spectroscopy and 3D surface topography based on white-light interferometry. Furthermore, Rocwell C indentation tests are conducted to evaluate the adhesion of HFCVD diamond and DLC films grown onto WC-Co substrates. SEM and 3D surface topography based on white-light interferometry are also used to investigate the worn region on the surfaces of diamond and DLC films. The friction tests suggest that the obtained friction coefficient curves that of various contacts exhibit similar evolution tendency. For a given counterface, DLC films present lower stable friction coefficients than HFCVD diamond films under the same sliding conditions. The cutting tests results indicate that flank wear of the HFCVD diamond coated insert is lower than that of DLC coated insert before diamond films peeling off.

Customized bentonite pellets. Manufacturing, performance and gap filling properties

Energy Technology Data Exchange (ETDEWEB)

Marjavaara, P.; Holt, E.; Sjoeblom, V. [VTT Technical Research Centre of Finland, Espoo (Finland)

2013-12-15

The goal of this work was to provide knowledge about how to manufacture customized bentonite pellets and how customized bentonite pellets perform in practice during the nuclear repository construction process. The project was mainly focused on laboratory experimental tests to optimize the pellet filling by customizing the raw materials and pellet manufacturing. Bentonite pellets were made using both extrusion and roller compaction methods. The pellets were intended for use in gaps between compacted bentonite and the rock walls in both buffer deposition holes and tunnel backfilling. Performance of different types of custom-made pellets were evaluated with regard to their ease of manufacturing, density, crush strength, abrasion resistance, water holding capacity, free swelling and also their thermal conductivity. These evaluations were done in both Finland (by VTT) and Canada (by AECL). Over 50 different varieties of pellets were roller-compaction manufactured at AECL in Canada and 20 types of extrusion pellets at VTT in Finland. The parameters that were varied during manufacturing included: bentonite raw material type, water content, pellet sizes, bentonite compaction machine parameters, use of recycled pellets, and addition of two different types of filler (illite or granitic sand) at varying addition percentages. By examining the pellets produced with these methods and materials the performance and behaviour of the bentonite pellets were evaluated in laboratory with selected tests. The work done using extrusion pellets showed that it was possible to manufacture pellets with higher water contents, up to 21 % from MX-80. This water content value was higher than what was typically possible using roller-compaction method in this study. Higher water content values allow closer compatibility with the designed bentonite buffer water content. The extrusion tests also showed that the required production simulation runs could be made successfully with reference type of MX

A study of full width at half maximum (FWHM) according to the filter's cut off level in SPECT camera

International Nuclear Information System (INIS)

Park, Soung Ock; Kwon, Soo Il

2003-01-01

Filtering is necessary to reduce statistical noise and to increase image quality in SPECT images. Noises controlled by low-pass filter designed to suppress high spatial frequency in SPECT image. Most SPECT filter function control the degree of high frequency suppression by choosing a cut off frequency. The location of cut off frequency determines the affect image noise and spatial resolution. If select the low cut off frequency, its provide good noise suppression but insufficient image quantity and high cut off frequencies increase the image resolution but insufficient noise suppression. The purpose of this study was to determines the optimum cut off level with comparison of FWHM according to cut off level in each filters-Band-limited, Sheep-logan, Sheep-logan Hanning, Generalized Hamming, Low pass cosine, Parazen and Butterworth filter in SPECT camera. We recorded image along the X, Y, Z-axis with 99m TcO 4 point source and measured FWHM by use profile curve. We find averaged length is 9.16 mm ∼ 18.14 mm of FWHM in X, Y, and Z-axis, and Band-limited and Generalized Hamming filters measures 9.16 mm at 0.7 cycle/pixel cut off frequency

The Optimal Volume Fraction in Percutaneous Vertebroplasty Evaluated by Pain Relief, Cement Dispersion, and Cement Leakage: A Prospective Cohort Study of 130 Patients with Painful Osteoporotic Vertebral Compression Fracture in the Thoracolumbar Vertebra.

Science.gov (United States)

Sun, Hai-Bo; Jing, Xiao-Shan; Liu, Yu-Zeng; Qi, Ming; Wang, Xin-Kuan; Hai, Yong

2018-06-01

To probe the relationship among cement volume/fraction, imaging features of cement distribution, and pain relief and then to evaluate the optimal volume during percutaneous vertebroplasty. From January 2014 to January 2017, a total of 130 patients eligible for inclusion criteria were enrolled in this prospective cohort study. According to the different degrees of pain relief, cement leakage, and cement distribution, all patients were allocated to 2 groups. Clinical and radiologic characteristics were assessed to identify independent factors influencing pain relief, cement leakage, and cement distribution, including age, sex, fracture age, bone mineral density, operation time, fracture level, fracture type, modified semiquantitative severity grade, intravertebral cleft, cortical disruption in the vertebral wall, endplate disruption, type of nutrient foramen, fractured vertebral body volume, intravertebral cement volume, and volume fraction. A receiver operating characteristic curve was used to analyze the diagnostic value of the cement volume/fraction and then to obtain the optional cut-off value. The preoperative visual analog scale scores in the responders versus nonresponders patient groups were 7.37 ± 0.61 versus 7.87 ± 0.92 and the postoperative VAS scores in the responders versus nonresponders were 2.04 ± 0.61 versus 4.33 ± 0.49 at 1 week. There were no independent factors influencing pain relief. There were 95 (73.08%) patients who experienced cement leakage, and cortical disruption in the vertebral wall and cement fraction percentage were identified as independent risk factors by binary logistic regression analysis (adjusted odds ratio [OR] 2.935, 95% confidence interval [95% CI] 1.214-7.092, P = 0.017); (adjusted OR 1.134, 95% CI 1.026-1.254, P = 0.014). The area under the receiver-operating characteristic curve of volume fraction (VF%) was 0.658 (95% CI 0.549-0.768, P = 0.006 cement leakage was 21.545%, with a sensitivity of 69.50% and a

Localization of fluctuation measurement by wave scattering close to a cut off layer

International Nuclear Information System (INIS)

Zou, X.L.; Laurent, L.; Rax, J.M.; Lehner, T.

1990-01-01

The diagnostic of plasma fluctuations in tokamaks based on the scattering of an electromagnetic wave close to a cut off layer is investigated. A linear density profile is considered. An one-dimensional exact analysis is performed. Spatial and spectral localization of scattering process close to the cut off layer is studied and a modified Bragg rule is derived. The structure of pump and of scattered waves is analyzed. The diagnostic seems to be local and sensitive for low R fluctuations

Using Cut-off grade isograms to delineate ore body and calculate parameter

International Nuclear Information System (INIS)

Yu Yongfeng; Zhu Xiaobing; Deng Yonghui

2014-01-01

Taking a uranium mine for an example, using cut-off grade isograms to achieve automatic delineation of ore body and calculation of parameters are explored. With center line of catalog sampling as baseline, the number of sampling and length of sampling constructing rectangular grid and grade as elevation value, isograms of cut-off grade were drawn, thus achieving the delineation of the ore body. Then, the other parameters of the ore body can be calculated. Compared with the traditional hand drawing method, the work efficiency was greatly improved, and the material inquiry was more convenient. (authors)

Fast beam cut-off method in RF-knockout extraction for spot-scanning

CERN Document Server

Furukawa, T

2002-01-01

An irradiation method with magnetic scanning has been developed in order to provide accurate irradiation even for an irregular target shape. The scanning method has strongly required a lower ripple of the beam spill and a faster response to beam-on/off in slow extraction from a synchrotron ring. At HIMAC, RF-knockout extraction has utilized a bunched beam to reduce the beam-spill ripple. Therefore, particles near the resonance can be spilled out from the separatrices by synchrotron oscillation as well as by a transverse RF field. From this point of view, a fast beam cut-off method has been proposed and verified by both simulations and experiments. The maximum delay from the beam cut-off signal to beam-off has been improved to around 60 mu s from 700 mu s by a usual method. Unwanted dose has been considerably reduced by around a factor of 10 compared with that by the usual method.

Changes on the mineralogical and physico-chemical properties of a compacted bentonite in contact with hyperalkaline pore fluids

International Nuclear Information System (INIS)

Fernandez, A.M.; Melon, A.; Sanchez, D.M.

2010-01-01

Document available in extended abstract form only. In high-level radioactive waste disposal (HLW) concepts, compacted bentonites are being considered in many countries as a sealing material because of their low permeability, high swelling capacity and high plasticity. In the case of the geological disposal of nuclear wastes in argillaceous host formations, concrete will be also used as support of tunnels and galleries and as waste containment material. Therefore, the bentonite barrier will become saturated with the water resulting from the host-rock/concrete interaction. An understanding of the rate and nature of the bentonite alteration, as well as the evolution of the bentonite pore water in the long-term is important for performance assessment. In this work the behaviour of the bentonite has been simulated in a laboratory test. A concrete-bentonite interaction experiment has been performed at a high solid to liquid ratio with FEBEX bentonite. The aim of the experiment was to analyse the buffering capacity of the bentonite and the clay mineral stability in a high-pH environment over a long contact period. The rate of pH buffering capacity of the bentonite is related to its surface hydroxyl sites (≡SOH) located along the edges of the clay platelets (fast reaction), and the montmorillonite crystal lattice itself (governed by reaction kinetics). Two infiltration tests with hyper-alkaline water were performed with FEBEX bentonite compacted at a dry density of 1.65 g/cm 3 with a hygroscopic water content (w.c.) of 13.4% in small-scale hermetic cells (50- mm diameter and 25-mm high). The experiments were running for 1.65 years under anoxic conditions inside an anoxic glove (< 1 ppm O 2 ) box and at temperature of 30-35 deg. C. The type of alkaline solution was a Na-K-OH water in equilibrium with portlandite, Ca(OH) 2 , at pH 13.5. This water is representative of an average pore water of a mortar made with CEM-I-SR type Portland cement (sulphate-resistant) at a 0

The normative score and the cut-off value of the Oswestry Disability Index (ODI).

Science.gov (United States)

Tonosu, Juichi; Takeshita, Katsushi; Hara, Nobuhiro; Matsudaira, Ko; Kato, So; Masuda, Kazuhiro; Chikuda, Hirotaka

2012-08-01

The Oswestry Disability Index (ODI) is one of the most common scoring systems used for patients with low back pain (LBP). Although the normative score of the ODI was reported to be 10.19 in a review article, no study has calculated the normative score after adjusting the value based on the age distribution. In addition, none of the previous studies has estimated the cut-off value which separates LBP with disability from LBP without disability. The purpose of this study was to estimate the normative score by adjusting the data for age distribution in Japan, and to determine the cut-off value which separates LBP with disability from LBP without disability. We conducted an internet survey on LBP using the Japanese version of the ODQ. A total of 1,200 respondents, composed of 100 males and 100 females in each age group (from the 20s to 70s), participated in this study. We also asked them to provide information about their backgrounds. We estimated the normative score after correcting for the age distribution of Japan. We also estimated the ODI of those with or without disability, the factors associated with the ODI, and the cut-off value which separates LBP with disability from LBP without disability. The participants' backgrounds were similar to the national survey. The normative score of the ODI was estimated at 8.73. The ODI of the LBP with disability group was 22.07. Those with sciatica and obese subjects showed higher ODI than those without. The optimal cut-off value was estimated to be 12. We defined the normative score and the cut-off value of the ODI.

characterization of geotechnical properties of lateritic soil-bentonite

African Journals Online (AJOL)

2013-03-01

Mar 1, 2013 ... cilities should ensure minimum fluid flow through or into the repository ... were evaluated using the rigid wall permeameter un- der falling ... cell pressure [22]. 3. Results .... them to retain a portion of water (double layer water) that may ... water in the pore space. ... The effect of bentonite content on volumetric.

Spectrally selective solar absorber with sharp and temperature dependent cut-off based on semiconductor nanowire arrays

Science.gov (United States)

Wang, Yang; Zhou, Lin; Zheng, Qinghui; Lu, Hong; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

2017-05-01

Spectrally selective absorbers (SSA) with high selectivity of absorption and sharp cut-off between high absorptivity and low emissivity are critical for efficient solar energy conversion. Here, we report the semiconductor nanowire enabled SSA with not only high absorption selectivity but also temperature dependent sharp absorption cut-off. By taking advantage of the temperature dependent bandgap of semiconductors, we systematically demonstrate that the absorption cut-off profile of the semiconductor-nanowire-based SSA can be flexibly tuned, which is quite different from most of the other SSA reported so far. As an example, silicon nanowire based selective absorbers are fabricated, with the measured absorption efficiency above (below) bandgap ˜97% (15%) combined with an extremely sharp absorption cut-off (transition region ˜200 nm), the sharpest SSA demonstrated so far. The demonstrated semiconductor-nanowire-based SSA can enable a high solar thermal efficiency of ≳86% under a wide range of operating conditions, which would be competitive candidates for the concentrated solar energy utilizations.

Anthropometric parameters’ cut-off points and predictive value for metabolic syndrome in women from Cartagena, Colombia

Directory of Open Access Journals (Sweden)

Gustavo José Mora-García

2014-03-01

Full Text Available Objective. To estimate anthropometric parameters’ (APs cut-off points and association for metabolic syndrome (MetS. Materials and methods. A cross-sectional study was carried out with a total of 434 adult women from Cartagena de Indias, Colombia, in 2012. APs measured were waist circumference (WC, body mass index (BMI, body adiposity index (BAI, waist-hip ratio (WHR and waist-height ratio (WHtR. Cut-off points were estimated by a receiver operating characteristic curve (ROC. Logistic regression was applied to estimate possible associations. Results. Cut-off points for WC, BMI, BAI, WHR and WHtR were 85 cm, 28 kg/m2, 39%, 0.80 and 56, respectively. Only WHtR was associated to MetS (OR=1.11, CI95% [1.07-1.15]. Conclusion. WC cut-off point was higher than those proposed for Latin-American women by the Joint Interim Statement (JIS. WHtR had a low predictive value for MetS.

Determination of the stresses and displacements in the cut off curtain body executed by the << Wall-in-the ground >> method.; Opredelenie napryazhenij i peremeshchenij v tele protivofil`tratsionnoj zavesy, vypolnennoj metodom << stena v grunte >>.

Energy Technology Data Exchange (ETDEWEB)

Snisarenko, V I; Mel` nikov, A I [Myinyisterstvo Budyivel` noyi Arkhyitekturi, Kyiv (Ukraine); [Myizhgaluzevij Naukovo-Tekhnyichnij Tsentr ` ` Ukrittya ` ` , Natsyional` na Akademyiya Nauk Ukrayini, Chornobil` (Ukraine)

1994-12-31

Construction of the cut-off-curtain (COC) is analyzed as a possible variant to reduce the rate of radioactive horizontal migration. Such constructions can be executed by the << wall-in-the ground >> method. The theoretical analysis of the stress-strained state of the carried out using the methods of the theory of elasticity and of the limit equilibrium of the strewing medium. Theoretical dependences are obtained and formulas for practical calculations of the COC-body stress-strained state in the depth intervals which are of practical interest are suggested. The dependences obtained may be used to calculate the consolidation parameters and filtration coefficients, to choose materials for the COC body, geometrical size and film elements included.

Hydrothermal alkaline stability of bentonite barrier by concrete interstitial wastes; Alteracion alcalina hidrotermal de la barrera de bentonita por aguas intersticiales de cementos

Energy Technology Data Exchange (ETDEWEB)

Leguey Jimenez, S; Cuevas Rodriguez, J; Ramirez Martin, S; Vigil de la villa Mencia, R.; Martin Barca, M [Universidad Autonoma de Madrid, Madrid (Spain)

2002-07-01

At present, the main source of High Level radioactive Waste (HLW) is the electrical energy production during all the steps of developing. In almost all the countries with nuclear programs, the option for the final management of HLW is the Deep Geological Repository (DGR) based on the concept of multi barrier. According to this concept, the waste is isolated from biosphere by the interposition of confinement barriers. Two of the engineering barriers in the Spanish design of DGR in granitic rock are compacted bentonite and concrete. The bentonite barrier is the backfilling and sealing material for the repository gallery, because of its mechanical and physico-chemical properties. The main qualities of concrete as a component of a multi barrier system are its low permeability, mechanical resistance and chemical properties. With regard to chemical composition of concrete, the alkaline nature of cement pore water lowers the solubility of many radioactive elements. However, structural transformation in smectite, dissolution or precipitation of minerals and, consequently, changes in the bentonite properties could occurs in the alkaline conditions generated by the cement degradation. The main objective of the present work is to evaluate the effect of concrete in the stability of Spanish reference bentonite (La Serrata of Nijar, Almeria, Spain) in conditions similar to those estimated in a DGR in granitic rock. Because of the main role of bentonite barrier in the global performance of the repository, the present study is essential to guarantee its security. (Author)

The Cut-off Value of Blood Mercury Concentration in Relation to Insulin Resistance

Directory of Open Access Journals (Sweden)

Seok-Hoon Lee

2017-09-01

Full Text Available Background : Increased blood mercury concentration is associated with inflammation, and chronic inflammation can cause insulin resistance. We examined the cut-off value of blood mercury in relation to an increased score on the homeostasis model assessment for insulin resistance (HOMA-IR. Methods : We used data from the Korean National Health and Nutrition Examination Survey (2008–2010. Relevant data from 5,184 subjects (2,523 men and 2,661 women were analyzed cross-sectionally. General linear analysis was performed to evaluate the relationship between HOMA-IR score and blood mercury concentration. In addition, we determined the cut-off value of blood mercury concentration in relation to increased HOMA-IR score (> 2.34 using an ROC curve. Results : The mean value of blood mercury concentration in men and women was 5.88 μg/L and 4.11 μg/L, respectively. In men, comparing to the first quartile, HOMA-IR score increased significantly in the third and fourth blood mercury quartiles. In women, however, the increase in HOMA-IR score was not significant. The cut-off value that best represented the association between increased HOMA-IR score and blood mercury concentration in men was found to be 4.71 μg/L. Conclusion : Blood mercury concentration was associated with increased HOMA-IR score in men, and the cut-off value of blood mercury concentration that was correlated with increased HOMA-IR score was around 4.71 μg/L.

Environmental trade-offs of tunnels vs cut-and-cover subways

Science.gov (United States)

Walton, M.

1978-01-01

Heavy construction projects in cities entail two kinds of cost - internal cost, which can be defined in terms of payments from one set of parties to another, and external cost, which is the cost borne by the community at large as the result of disutilities entailed in construction and operation. Environmental trade-offs involve external costs, which are commonly difficult to measure. Cut-and-cover subway construction probably entails higher external and internal cost than deep tunnel construction in many urban geological environments, but uncertainty concerning the costs and environmental trade-offs of tunneling leads to limited and timid use of tunneling by American designers. Thus uncertainty becomes a major trade-off which works against tunneling. The reverse is true in Sweden after nearly 30 years of subway construction. Econometric methods for measuring external costs exist in principle, but are limited in application. Economic theory based on market pressure does not address the real problem of urban environmental trade-offs. Nevertheless, the problem of uncertainty can be addressed by comparative studies of estimated and as-built costs of cut-and-cover vs tunnel projects and a review of environmental issues associated with such construction. Such a study would benefit the underground construction industry and the design of transportation systems. It would also help solve an aspect of the urban problem. ?? 1978.

Bentonite in the repository - Manufacture of bentonite blocks. A literature study

International Nuclear Information System (INIS)

Hultgren, Aa.

1995-09-01

Activities in nuclear power countries are reviewed, concerning developments in the use of bentonite for backfilling in nuclear waste repositories, in particular regarding manufacture of bentonite-blocks. Only one report was found which in detail describes the manufacture of highly compacted blocks of bentonite. Use of bentonite for sealing boreholes etc in the oil- and gas industry was also covered in the literature study. 19 refs, 3 tabs

Prevalence and risk factors with overweight and obesity among Vietnamese adults: Caucasian and Asian cut-offs.

Science.gov (United States)

Trinh, Oanh T H; Nguyen, Nguyen D; Phongsavan, Philayrath; Dibley, Michael J; Bauman, Adrian E

2009-01-01

To determine the prevalence and factors associated with overweight/obesity among adults in Ho Chi Minh City (HCMC) using Caucasian and Asian cut-offs. A cross-sectional survey. In 2005, 1,971 adults aged 25-64 years in HCMC were randomly selected using a proportional to population size sampling method to estimate the prevalence of overweight and obesity, measured by body mass index (BMI) and waist circumference. Multivariable logistic models were used to examine associations between overweight/obesity and socioeconomic status, health-related behaviors, and biochemical indices of chronic disease risk. The prevalence of overweight and obesity using the Caucasian BMI cut-offs were 13.9% and 1.8% respectively, and those with the Asian BMI cut-offs were 27.5% and 5.7%, respectively. The abdominal adiposity rates were higher than the BMI overweight and obesity rates in women, but not in men. Increasing age, low education, high household wealth index, high levels of sitting and reclining time, cholesterol and high blood pressure were significantly associated with overweight and obesity. Current smoking and sedentary leisure time was significantly negatively associated with this status in men. Associations between overweight/obesity and metabolic disorders were evident using both cut-offs. Asian cut-offs identified more risk factors and therefore could be considered for defining at-risk groups. The results highlight the importance of intervention programs to prevent overweight/obesity in young adults.

Minimizing waste (off-cuts using cutting stock model: The case of one dimensional cutting stock problem in wood working industry

Directory of Open Access Journals (Sweden)

Gbemileke A. Ogunranti

2016-09-01

Full Text Available Purpose: The main objective of this study is to develop a model for solving the one dimensional cutting stock problem in the wood working industry, and develop a program for its implementation. Design/methodology/approach: This study adopts the pattern oriented approach in the formulation of the cutting stock model. A pattern generation algorithm was developed and coded using Visual basic.NET language. The cutting stock model developed is a Linear Programming (LP Model constrained by numerous feasible patterns. A LP solver was integrated with the pattern generation algorithm program to develop a one - dimensional cutting stock model application named GB Cutting Stock Program. Findings and Originality/value: Applying the model to a real life optimization problem significantly reduces material waste (off-cuts and minimizes the total stock used. The result yielded about 30.7% cost savings for company-I when the total stock materials used is compared with the former cutting plan. Also, to evaluate the efficiency of the application, Case I problem was solved using two top commercial 1D-cutting stock software.  The results show that the GB program performs better when related results were compared. Research limitations/implications: This study round up the linear programming solution for the number of pattern to cut. Practical implications: From Managerial perspective, implementing optimized cutting plans increases productivity by eliminating calculating errors and drastically reducing operator mistakes. Also, financial benefits that can annually amount to millions in cost savings can be achieved through significant material waste reduction. Originality/value: This paper developed a linear programming one dimensional cutting stock model based on a pattern generation algorithm to minimize waste in the wood working industry. To implement the model, the algorithm was coded using VisualBasic.net and linear programming solver called lpsolvedll (dynamic

A geometric classification of traveling front propagation in the Nagumo equation with cut-off

International Nuclear Information System (INIS)

Popovic, N

2011-01-01

An important category of solutions to reaction-diffusion systems of partial differential equations is given by traveling fronts, which provide a monotonic connection between rest states and maintain a fixed profile when considered in a co-moving frame. Reaction-diffusion equations are frequently employed in the mean-field (continuum) approximation of discrete (many-particle) models; however, the quality of this approximation deteriorates when the number of particles is not sufficiently large. The (stochastic) effects of this discreteness have been modeled via the introduction of (deterministic) 'cut-offs' that effectively deactivate the reaction terms at points where the particle concentration is below a certain threshold. In this article, we present an overview of the effects of such a cut-off on the front propagation dynamics in a prototypical reaction-diffusion system, the classical Nagumo equation. Our analysis is based on the method of geometric desingularization ('blow-up'), in combination with dynamical systems techniques such as invariant manifolds and normal forms. Using these techniques, we categorize front propagation in the cut-off Nagumo equation in dependence of a control parameter, and we classify the corresponding propagation regimes ('pulled,' 'pushed,' and 'bistable') in terms of the bifurcation structure of a projectivized system of equations that is obtained from the original traveling front problem, after blow-up. In particular, our approach allows us to determine rigorously the asymptotics (in the cut-off parameter) of the correction to the front propagation speed in the Nagumo equation that is due to a cut-off. Moreover, it explains the structure of that asymptotics (logarithmic, superlinear, or sublinear) in dependence of the front propagation regime. Finally, it enables us to calculate the corresponding leading-order coefficients in the resulting expansions in closed form.

A PROBLEM OF CUTTING OFF THE LAMINATED SEMIS TYPE PLATE

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Florin Ciofu

2012-11-01

Full Text Available A problem often coped on many domains such as wood manufacturing, glass, plastics and metallic platework industry, is the shaping or cutting off a big plate in many pieces. With this purpose there are algorithms of optimizing for positioning the parts following to be cut off from a row plate. From mathematical point of view, in positioning the parts on a raw plate the number of solutions increase four times evrey time a new part is added, and in case of finding the best solution for about few hundreds of pieces or parts would require years of processing on the most performant computers nowadays – for an analogy remember the famous story with the rice beads which the King had to pay to the master teaching him the chess: twice more for each square of the chessboard; for the total quantity assessment, King ascertained that the crops in his whole life wouldn’t have been enough.

Open Skies and monitoring a fissile materials cut-off treaty

International Nuclear Information System (INIS)

Allentuck, J.; Lemley, J.R.

1995-01-01

The Treaty on Open Skies (Open Skies) is intended among other things to provide, in the words of its preamble, means ''to facilitate the monitoring of compliance with existing or future arms control agreements.'' Open Skies permits overflights of the territory of member states by aircraft equipped with an array of sensors of various types. Their types and capabilities are treaty-limited. To find useful application in monitoring a cut-off treaty Open Skies would need to be amended. The number of signatories would need to be expanded so as to provide greater geographical coverage, and restrictions on sensor-array capabilities would need to be relaxed. To facilitate the detection of impending violations of a cut-off convention by Open Skies overflights, the data base provided by parties to the former should include among other things an enumeration of existing and former fuel cycle and research facilities including those converted to other uses, their precise geographic location, and a site plan

A general equation to obtain multiple cut-off scores on a test from multinomial logistic regression.

Science.gov (United States)

Bersabé, Rosa; Rivas, Teresa

2010-05-01

The authors derive a general equation to compute multiple cut-offs on a total test score in order to classify individuals into more than two ordinal categories. The equation is derived from the multinomial logistic regression (MLR) model, which is an extension of the binary logistic regression (BLR) model to accommodate polytomous outcome variables. From this analytical procedure, cut-off scores are established at the test score (the predictor variable) at which an individual is as likely to be in category j as in category j+1 of an ordinal outcome variable. The application of the complete procedure is illustrated by an example with data from an actual study on eating disorders. In this example, two cut-off scores on the Eating Attitudes Test (EAT-26) scores are obtained in order to classify individuals into three ordinal categories: asymptomatic, symptomatic and eating disorder. Diagnoses were made from the responses to a self-report (Q-EDD) that operationalises DSM-IV criteria for eating disorders. Alternatives to the MLR model to set multiple cut-off scores are discussed.

The Cut-off Values of Triglycerides and Glucose Index for Metabolic Syndrome in American and Korean Adolescents.

Science.gov (United States)

Moon, Shinje; Park, Joon Sung; Ahn, Youhern

2017-03-01

The aim of this study was to establish ethnic- and gender-specific cut-off values of triglycerides and glucose index (TyG index) for clinical usefulness in a representative sample of Mexican American, Non-Hispanic White, Non-Hispanic Black, and Korean adolescents. The data were collected from datasets of the National Health and Nutrition Examination Survey between 1999 and 2012, and the Korean National Health and Nutrition Examination Survey between 2005 and 2013. Receiver operating characteristic curve analysis was used to find valid cut-off values of the TyG index for metabolic syndrome. The total number of eligible participants was 3,164 in the US and 4,873 in Korea. The optimal cut-off value with the Cook et al. definition revealed 8.55 in Mexican American, 8.55 in Non-Hispanic White, 8.35 in Non-Hispanic Black, and 8.45 in Korean, respectively. The cut-off value with the de Ferranti et al. definition was 8.45, 8.45, 8.15, and 8.35, and the cut-off value with the International Diabetes Federation definition was 8.65, 8.65, 8.15, and 8.55, respectively. These findings may be clinically useful for evaluating insulin resistance for determining metabolic abnormalities in adolescents.

The Optimization of Immobilization for the Low-Activity Waste of theEvaporation Product with Cement

International Nuclear Information System (INIS)

Supardi

2000-01-01

The experimental investigation of immobilization the low active wasteconcentration containing 2.44x10 -3 μCi/cc a great deal of NaNO 3 withcement was done. The immobilization process was carried out by mixing cement,water, concentrate, and Ca-bentonite with a given ratio within a glassbeaker. The mixture was then stirred with an electrical hand mixer untilhomogeneous. The studied immobilization condition were the influences of theweight ratio water to cement, the weight ratio of concentrate to cement withwhich the concentrate pH was varied, and the influence of the addition ofCa-bentonite (% in weight) with the optimum pH of concentrate. The sample inthe container with the size of 2.54 cm in diameter and 3.0 cm in height wasmade of polyethylene and was covered by a tight lid and was cured for 28days. After the sample was cured for 28 days and then it was taken out of thecontainer. This sample quality was ready for being tested. The quality ofcementation product tested compressive strength, density, chemical stability,irradiation stability and thermal stability. The optimum results ofinvestigation were the weight ratio of water to cement = 0.30, thecompressive strength of 30.37 N/mm 2 . For the immobilization of the waste andcement with the optimum pH being used, yielded in the compressive strength of28.07 N/mm 2 . Further more from the condition of waste and cement at theoptimum pH which was added by the optimum Ca-bentonite gained the compressivestrength of 33.64 N/mm 2 before irradiation, where as after irradiation thecompressive strength was 32.41 N/mm 2 . The optimum thermal test resultachieved was 250 o C with the compressive strength of 44.10 N/mm 2 . For theleaching test results after being cured for 91 days in the distilled watermedia was 0.47x10 -4 gcm -2 day -1 , while in the sea water was 0.66x10 -4 gcm -2 day -1 . Water medium activity until 91 days = 3.1x10 -7 μCi/cc,MPC from ICRP = 8.1x10 -7 μCi/cc. The experimental investigation ofcemented waste

A study of full width at half maximum (FWHM) according to the filter's cut off level in SPECT camera

Energy Technology Data Exchange (ETDEWEB)

Park, Soung Ock [Dongnam Health College, Suwon (Korea, Republic of); Kwon, Soo Il [Kyonggi University, Suwon (Korea, Republic of)

2003-06-15

Filtering is necessary to reduce statistical noise and to increase image quality in SPECT images. Noises controlled by low-pass filter designed to suppress high spatial frequency in SPECT image. Most SPECT filter function control the degree of high frequency suppression by choosing a cut off frequency. The location of cut off frequency determines the affect image noise and spatial resolution. If select the low cut off frequency, its provide good noise suppression but insufficient image quantity and high cut off frequencies increase the image resolution but insufficient noise suppression. The purpose of this study was to determines the optimum cut off level with comparison of FWHM according to cut off level in each filters-Band-limited, Sheep-logan, Sheep-logan Hanning, Generalized Hamming, Low pass cosine, Parazen and Butterworth filter in SPECT camera. We recorded image along the X, Y, Z-axis with {sup 99m}TcO{sub 4} point source and measured FWHM by use profile curve. We find averaged length is 9.16 mm {approx} 18.14 mm of FWHM in X, Y, and Z-axis, and Band-limited and Generalized Hamming filters measures 9.16 mm at 0.7 cycle/pixel cut off frequency.

Normal Limits of Electrocardiogram and Cut-Off Values for Left ...

African Journals Online (AJOL)

olayemitoyin

The cut-off values for Sokolow-Lyon, Cornell and Araoye criteria for assessment of left ventricular hypertrophy. (LVH) were higher than those previously in ... MATERIALS AND METHODS. This was a cross-sectional descriptive ..... criteria, Araoye code system and Ogunlade criterion were derived from the addition of two or ...

Screening for Internet Addiction: An Empirical Study on Cut-off Points for the Chen Internet Addiction Scale

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Chih-Hung Ko

2005-12-01

Full Text Available The aim of this study was to establish the optimal cut-off points of the Chen Internet Addiction Scale (CIAS, to screen for and diagnose Internet addiction among adolescents in the community by using the well- established diagnostic criteria of Internet addiction. This survey of 454 adolescents used screening (57/58 and diagnostic (63/64 cut-off points of the CIAS, a self-reported instrument, based on the results of systematic diagnostic interviews by psychiatrists. The area under the curve of the receiver operating characteristic curve revealed that CIAS has good diagnostic accuracy (89.6%. The screening cut-off point had high sensitivity (85.6% and the diagnostic cut-off point had the highest diagnostic accuracy, classifying 87.6% of participants correctly. Accordingly, the screening point of the CIAS could provide a screening function in two-stage diagnosis, and the diagnostic point could serve as a diagnostic criterion in one-stage massive epidemiologic research.

Current MUAC Cut-Offs to Screen for Acute Malnutrition Need to Be Adapted to Gender and Age: The Example of Cambodia

Science.gov (United States)

Fiorentino, Marion; Sophonneary, Prak; Laillou, Arnaud; Whitney, Sophie; de Groot, Richard; Perignon, Marlène; Kuong, Khov; Berger, Jacques; Wieringa, Frank T.

2016-01-01

Background Early identification of children malnutrition is a priority. Acute malnutrition is defined by the World Health Organization as a mid-upper-arm circumference (MUAC) malnutrition in communities, but MUAC cut-offs currently recommended by WHO do not identify the majority of children with weight-for-height Z-score (5 yrs. Therefore, this study aimed at defining gender and age-specific cut-offs to improve sensitivity of MUAC as an indicator of acute malnutrition. Methods To establish new age and gender-specific MUAC cut-offs, pooled data was obtained for 14,173 children from 5 surveys in Cambodia (2011–2013). Sensitivity, false positive rates, and areas under receiver-operator characteristic curves (AUC) were calculated using wasting for children 80% with the new cut-offs in comparison with the current WHO cut-offs. Conclusion Gender and age specific MUAC cut-offs drastically increased sensitivity to identify children with WHZ-score malnutrition at the community level. PMID:26840899

Projection systems with a cut-off line for automotive applications

Science.gov (United States)

Kloos, G.; Eichhorn, K.

2005-08-01

The lighting systems of a car provide a variety of challenges from the point of view of illumination science and technology. Engineering work in this field has to deal both with reflector and lens design as well as with opto-mechanical design and sensor technology. It has direct implications on traffic safety and the efficiency in which energy is used. Therefore, these systems are continuously improved and optimized. In this context, adaptive systems that we investigate for automotive applications gain increasing importance. The properties of the light distribution in the vicinity of the cut-off line are of key importance for the safe and efficient operation of automotive headlamps. An alternative approach is proposed to refine the description of these properties in an attempt to make it more quantitative. This description is intended to facilitate intercomparison between different systems and/or to study environmental influences on the cut-off line of a system under investigation. Designing projection systems it is necessary to take a delicate trade-off between efficiency, light-distribution characteristics, mechanical boundary conditions, and legal requirements into account. Considerations and results on optical properties of three-axial reflectors in dependence of layout parameters will be given. They can serve as a guideline for the optical workshop and for free-form optimization.

Defining a BMI Cut-Off Point for the Iranian Population: The Shiraz Heart Study.

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Mohammad Ali Babai

Full Text Available In this study we evaluated and redefined the optimum body mass index (BMI cut-off point for the Iranian population based on metabolic syndrome (MeS risk factors. We further evaluated BMI cut-off points with and without waist circumference (WC as a cofactor of risk and compared the differences. This study is part of the largest surveillance programs conducted in Shiraz, Iran, termed the Shiraz Heart study. Our study sample included subjects between the ages of 20 to 65 years old. After excluding pregnant women, those with missing data and those with comorbid disease, a total of 12283 made up the study population. The participants underwent a series of tests and evaluations by trained professionals in accordance with WHO recommendations. Hypertension, abnormal fasting blood sugar (FBS, triglyceride (TG and high density lipoprotein cholesterol (HDL (in the context of the definition of metabolic syndrome were prevalent among 32.4%, 27.6%, 42.1 and 44.2% of our participants, respectively. Women displayed higher rates of overall obesity compared to men (based on the definition by the WHO as higher than 30 kg/m2. Regarding MeS, 38.9% of our population had the all symptoms of MeS which was more prevalent among women (41.5% vs. 36%. When excluding WC in the definition of MeS, results showed that males tend to show a higher rate of metabolic risk factors (19.2% vs. 15.6%. Results of multivariate analysis showed that parallel to an increase in BMI, the odds ratio (OR for acquiring each component of the metabolic syndrome increased (OR = 1.178; CI: 1.166-1.190. By excluding WC, the previous OR decreased (OR = 1.105; CI: 1.093-1.118. Receiver Operating Characteristic (ROC curve analysis showed that the optimum BMI cut-off point for predicting metabolic syndrome was 26.1 kg/m2 and 26.2 kg/m2 [Accuracy (Acc = 69% and 61%, respectively] for males and females, respectively. The overall BMI cut-off for both sexes was 26.2 kg/m2 (Acc = 65% with sensitivity and

A Study on the Manufacturing Properties of Crack Self-Healing Capsules Using Cement Powder for Addition to Cement Composites

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Yun-Wang Choi

2017-01-01

Full Text Available We fabricated crack self-healing capsules using cement powder for mixing into cement composites and evaluated the properties of the capsule manufacturing process in this study. The manufacture of the self-healing capsules is divided into core production processing of granulating cement in powder form and a coating process for creating a wall on the surfaces of the granulated cement particles. The produced capsules contain unhardened cement and can be mixed directly with the cement composite materials because they are protected from moisture by the wall material. Therefore, the untreated cement is present in the form of a capsule within the cement composite, and hydration can be induced by moisture penetrating the crack surface in the event of cracking. In the process of granulating the cement, it is important to obtain a suitable consistency through the kneading agent and to maintain the moisture barrier performance of the wall material. We can utilize the results of this study as a basis for advanced self-healing capsule technology for cement composites.

Sealing performance assessments of bentonite and bentonite/crushed rock plugs

International Nuclear Information System (INIS)

Ouyang, Shoung.

1990-01-01

Bentonite and mixtures of bentonite and crushed rock are potential sealing materials for high level nuclear waste repositories. The materials have been used to form cap layers to reduce infiltration for mined waste tailings and can also be used to construct clay liners for municipal as well as industrial waste managements. American Colloid C/S granular dentonite and Apache Leap tuff have been mixed to prepare samples for laboratory flow testing. Bentonite weight percent and crushed tuff gradation are the major variables studied. The sealing performance assessments include high injection pressure flow tests, polyaxial flow tests, high temperature flow tests, and piping tests. The results indicate that an appropriate composition would have at least 25% bentonite by weight mixed with well-graded crushed rock. Hydraulic properties of the mixture plugs may be highly anisotropic if significant particle segregation occurs during sample installation and compaction. Temperature has no negative effects on the sealing performance within the test range from room temperature to 60C. The piping damage to the sealing performance is small if the maximum hydraulic gradient does not exceed 120 and 280 for 25 and 35% bentonite content, respectively. The hydraulic gradients above which flow of bentonite may take place are deemed critical. Analytical work includes the introduction of bentonite occupancy percentage and water content at saturation as two major parameters for the plug design. A permeability model developed is useful for the prediction of permeability in clays. A piping model permits the estimation of critical hydraulic gradient allowed before the flow of bentonite takes place. It can also be used to define the maximum allowable pore diameter of a protective filter layer

Accuracy of unfolded map method for determining the left ventricular border. Evaluation of the cut-off value from autopsy finding

International Nuclear Information System (INIS)

Sugibayashi, Keiichi; Abe, Yoshiteru; Suga, Yutaka

1996-01-01

To improve the quantification of the left ventricular surface area (LVSA) by unfolded map method, we evaluated the cut-off value for determining the left ventricular border. The LVSA measured by unfolded map was compared with those measured using myocardial phantom and autopsy findings. The relative error (RE) was calculated as difference between LVSA in phantom and area of unfolded map. In phantom study, the cut-off value was calculated as 73.3±0.5% when the RE was zero. In autopsy study, the cut-off value was 74.0±7.2%. The area of unfolded map had good correlation with LVSA at autopsy when the cut-off value was 74% (r=0.83, p<0.003). The diameter of left ventricle at autopsy was compared with that of beating heart obtained by two-dimensional echocardiography, because the area of unfolded map was greater than LVSA at autopsy. The ratio of LVSA at autopsy to beating heart was calculated as 1.37. The suitable cut-off value was evaluated as 55.6% when the unfolded map area obtained by autopsy was increased 1.37 magnifications. There was a good correlation between LVSA of unfolded map (cut-off=56%) and the LVSA at autopsy (r=0.90, p<0.001). These results suggest that the cut-off value for determining the left ventricular border in vivo is 56%. (author)

Evaluation of the Effect of Axial Wall Modification and Coping Design on the Retention of Cement-retained Implant-supported Crowns

Science.gov (United States)

Derafshi, Reza; Ahangari, Ahmad Hasan; Torabi, Kianoosh; Farzin, Mitra

2015-01-01

Background and aims. Because of compromised angulations of implants, the abutments are sometimes prepared. The purpose of this study was to investigate the effect of removing one wall of the implant abutment on the retention of cement-retained crowns. Materials and methods. Four prefabricated abutments were attached to analogues and embedded in acrylic resin blocks. The first abutment was left intact. Axial walls were partially removed from the remaining abutments to produce abutments with three walls. The screw access channel for the first and second abutments were completely filled with composite resin. For the third and fourth abutments, only partial filling was done. Wax-up models were made by CAD/CAM. Ten cast copings were fabricated for each abutment. The copings of fourth abutment had an extension into the screw access channel. Copings were cemented with Temp Bond. The castings were removed from the abutment using an Instron machine, and the peak removal force was recorded. A one-way ANOVA was used to test for a significant difference followed by the pairwise comparisons. Results. The abutments with opened screw access channel had a significantly higher retention than the two other abutments. The abutment with removed wall and no engagement into the hole by the castings exhibited the highest retention. Conclusion. Preserving the opening of screw access channel significantly increases the retention where one of the axial walls of implant abutments for cement-retained restorations is removed during preparation. PMID:25973152

Metals attenuation in minerally-enhanced slurry walls

International Nuclear Information System (INIS)

Evans, J.C.; Prince, M.J.; Adams, T.L.

1997-01-01

In current practice, a soil-bentonite slurry trench cutoff wall is a mixture of water, soil, and bentonite that is designed to serve as a passive barrier to ground water and contaminant transport. This study evaluated the transformation of a passive slurry trench cutoff wall barrier to an active barrier system. Conventional soil-bentonite vertical barriers presently serve as passive barriers to contaminated ground water. An active barrier will not only fulfill the functions of the present passive barrier system, but also retard contaminant transport by adsorptive processes. Attapulgite, Na-chabazite, and Ca-chabazite were added to open-quotes activateclose quotes the conventional soil-bentonite backfill. Batch extraction tests were performed to determine the partitioning coefficients of cadmium and zinc between the liquid and solid phase when in contact with the backfill mixes. Batch extraction and mathematical modeling results demonstrate the ability of an active barrier to retard the transport of cadmium and zinc. The reactivity of the soil-bentonite vertical barrier depends heavily on the inorganic being adsorbed. The reactivity of the barrier also depends on the adsorptive capabilities of the clay minerals added to the conventional soil-bentonite vertical barrier. The results of laboratory studies suggest that passive barrier systems can be transformed to active systems. Further, the data suggests that although conventional soil-bentonite vertical barriers are presently designed as passive barriers, they already have adsorptive capacity associated with active barriers

EVALUATION OF THE BENTONITE CONTENT IN SPENT FOUNDRY SANDS AS A FUNCTION OF HYDRAULIC CONDUCTIVITY COEFFICIENT

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Schirlene Chegatti

2013-06-01

Full Text Available This study evaluates the relationship of the bentonite content and hydraulic conductivity coefficient (k of waste foundry sands in tests of hydraulic conductivity in a flexible wall permeameter. The test samples had concentrations of activated sodium bentonite and natural sodium bentonite between 4% and 15%. It was also analyzed chemically the liquid leachate (aluminum, barium, chromium, cadmium, lead, phenols, iron, fluoride, and manganese, following de standard tests of Standard Methods 3111 B e D for the determination of this components in liquid samples. The experiments were supplemented with cation exchange capacity analysis. The results indicate that the values of are is related to the content of bentonite in waste foundry sand and the percolation from this waste disposal.

Evaluation of gas migration characteristics of compacted and saturated Ca-bentonite mixture

International Nuclear Information System (INIS)

Tanaka, Yukihisa; Hironaga, Michihiko

2014-01-01

In the current concept of near-surface pit disposal for low level radioactive waste, compacted bentonite mixture will be used as an engineered barrier mainly for inhibiting migration of radioactive nuclides. Hydrogen gas can be generated inside the engineered barrier mainly by the chemical interaction between aluminum and the alkaline component of cement, or water. If the gas generation rate exceeds the diffusion rate of gas molecules inside of the compacted bentonite mixture, gas will accumulate in the void space inside of the compacted bentonite mixture until its pressure becomes large enough for it to enter the compacted bentonite mixture as a discrete gaseous phase. It is expected to be not easy for gas to entering into the compacted bentonite mixture as a discrete gaseous phase because the pore of the compacted bentonite mixture is so minute. Therefore in this study, the gas migration characteristics and the effect of gas migration on the hydraulic conductivity of the compacted Ca-bentonite mixture are investigated by the gas migration tests. The effect of stress state on the migration characteristics is also investigated by the gas migration tests and by parametric study using the model of two phase flow through deformable porous media, which was originally developed by CRIEPI. Results of this study imply that : (1) Large gas breakthrough pressure, which is defined as a rapid increase of amount of discharged gas, is affected by initial stress conditions as well as Ca-bentonite content of the mixture. (2) Hydraulic conductivity measured after the large gas breakthrough is substantially the same that measured before the gas migration test. (3) Axial stress change and volume change of the specimen during the gas migration test can be reproduced by the numerical simulation using the model of two-phase flow through deformable porous media, which was originally developed by CRIEPI. (4) Gas migration of a small scale model is numerically simulated to investigate the

Age-adjusted D-dimer cut-off in the diagnostic strategy for deep vein thrombosis

DEFF Research Database (Denmark)

Nybo, Mads; Hvas, Anne-Mette

2017-01-01

BACKGROUND: Studies have indicated that use of an age-adjusted D-dimer cut-off value for patients above 50 years increases utility of the diagnostic strategy for pulmonary embolism. Evidence for the same approach regarding diagnosis of deep vein thrombosis (DVT) is, however, unclear. MATERIALS...... AND METHODS: A systematic literature review was conducted following the PRISMA Statement guideline to gather the existing knowledge on the use of an age-adjusted D-dimer cut-off in the diagnostic strategy for DVT. Studies were extracted from Medline and the Cochrane Library. The search period ended...

Waist circumference cut-off points for identification of abdominal obesity among the tunisian adult population.

Science.gov (United States)

Bouguerra, R; Alberti, H; Smida, H; Salem, L B; Rayana, C B; El Atti, J; Achour, A; Gaigi, S; Slama, C B; Zouari, B; Alberti, K G M M

2007-11-01

Waist circumference (WC) is a convenient measure of abdominal adipose tissue. It itself is a cardiovascular disease (CVD) and diabetes-risk factor and is strongly linked to other CVD risk factors. There are, however, ethnic differences in the relationship of WC to the other risk factors. The aim of this study was to determine the optimal cut-off points of WC and body mass index (BMI) at which cardiovascular risk factors can be identified with maximum sensitivity and specificity in a representative sample of the Tunisian adult population and to investigate any correlation between WC and BMI. We used a sample of the Tunisian National Nutrition Survey, a cross-sectional population-based survey, conducted in 1996 on a large nationally representative sample, which included 3435 adults (1244 men and 2191 women) of 20 years or older. WC, BMI, blood pressure and fasting blood measurements (plasma glucose, total cholesterol, triglycerides) were recorded. Receiver operating characteristic (ROC) curve analysis was used to identify optimal cut-off values of WC and BMI to identify with maximum sensitivity and specificity the detection of high blood pressure, hyperglycaemia, high blood cholesterol and hypertriglyceridaemia. ROC curve analysis suggested WC cut-off points of 85 cm in men and 85 cm in women for the optimum detection of high blood pressure, diabetes and dyslipidaemia. The optimum BMI cut-off points for predicting cardiovascular risk factors were 24 kg/m(2) in men and 27 kg/m(2) in women. The cut-off points recommended for the Caucasian population differ from those appropriate for the Tunisian population. The data show a continuous increase in odds ratios of each cardiovascular risk factor, with increasing level of WC and BMI. WC exceeding 85 cm in men and 79 cm in women correctly identified subjects with a BMI of >/=25 kg/m(2), sensitivity of >90% and specificity of >83%. Based on the ROC analysis, we suggest a WC of 85 cm for both men and women as appropriate cut-off

Determining the optimal system-specific cut-off frequencies for filtering in-vitro upper extremity impact force and acceleration data by residual analysis.

Science.gov (United States)

Burkhart, Timothy A; Dunning, Cynthia E; Andrews, David M

2011-10-13

The fundamental nature of impact testing requires a cautious approach to signal processing, to minimize noise while preserving important signal information. However, few recommendations exist regarding the most suitable filter frequency cut-offs to achieve these goals. Therefore, the purpose of this investigation is twofold: to illustrate how residual analysis can be utilized to quantify optimal system-specific filter cut-off frequencies for force, moment, and acceleration data resulting from in-vitro upper extremity impacts, and to show how optimal cut-off frequencies can vary based on impact condition intensity. Eight human cadaver radii specimens were impacted with a pneumatic impact testing device at impact energies that increased from 20J, in 10J increments, until fracture occurred. The optimal filter cut-off frequency for pre-fracture and fracture trials was determined with a residual analysis performed on all force and acceleration waveforms. Force and acceleration data were filtered with a dual pass, 4th order Butterworth filter at each of 14 different cut-off values ranging from 60Hz to 1500Hz. Mean (SD) pre-fracture and fracture optimal cut-off frequencies for the force variables were 605.8 (82.7)Hz and 513.9 (79.5)Hz, respectively. Differences in the optimal cut-off frequency were also found between signals (e.g. Fx (medial-lateral), Fy (superior-inferior), Fz (anterior-posterior)) within the same test. These optimal cut-off frequencies do not universally agree with the recommendations of filtering all upper extremity impact data using a cut-off frequency of 600Hz. This highlights the importance of quantifying the filter frequency cut-offs specific to the instrumentation and experimental set-up. Improper digital filtering may lead to erroneous results and a lack of standardized approaches makes it difficult to compare findings of in-vitro dynamic testing between laboratories. Copyright © 2011 Elsevier Ltd. All rights reserved.

Correlation between Body Mass Index, Gender, and Skeletal Muscle Mass Cut off Point in Bandung

OpenAIRE

Richi Hendrik Wattimena; Vitriana; Irma Ruslina Defi

2017-01-01

Objective: To determine the average skeletal muscle mass (SMM) value in young adults as a reference population; to analyze the correlation of gender, and body mass index to the cut off point; and to determine skeletal muscle mass cut off points of population in Bandung, Indonesia. Methods: This was a cross-sectional study involving 199 participants, 122 females and 77 males. The sampling technique used was the multistage random sampling. The participants were those who lived in four ma...

ELISA Cut-off Point for the Diagnosis of Human Brucellosis; a Comparison with Serum Agglutination Test

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Anahita Sanaei Dashti

2012-03-01

Full Text Available Background: Brucellosis is a world-wide disease, which has a diverse clinical manifestation, and its diagnosis has to be proven by laboratory data. Serum agglutination test (SAT is the most-widely used test for diagnosing brucellosis. The enzyme linked immunosorbent assay (ELISA can also determine specific antibody classes against brucella. It is a sensitive, simple and rapid test, which could be an acceptable alternative to SAT with fewer limitations, however, like any other new test it should be further evaluated and standardized for various populations. This study was planned to determine an optimal cut-off point, for ELISA which would offer maximum sensitivity and specificity for the test when compared to SAT.Methods: Four hundred and seven patients with fever and other compatible symptoms of brucellosis were enrolled in the study. Serum agglutination test, 2-Mercaptoethanol test, and ELISA were performed on their sera. Results: The cut-off point of 53 IU/ml of ELISA-IgG yielded the maximal sensitivity and specificity comparing to the other levels of ELISA-IgG, and was considered the best cut off-point of ELISA-IgG to diagnose acute brucellosis. At this cut-off, the sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were 84.09%, 85.38%, 62.20, 94.90, 5.75, 0.18, respectively.Conclusion: The best cut-off point of ELISA-IgG is 53 IU/ml, which yields the maximal sensitivity and specificity to diagnose acute brucellosis.

Triple Pancreatic Walled-off Fluid Collections Treated Simultaneously with Endoscopic Transmural Drainage.

Science.gov (United States)

Khalid, Sameen; Abbass, Aamer; Nellis, Eric; Shah, Shashin; Shah, Hiral

2018-01-09

Pancreatic pseudocysts and walled-off pancreatic necrosis arise as a complication of pancreatitis. Multiple fluid collections are seen in 5-20% of the patients who have walled-off peripancreatic fluid collections. There is a paucity of data regarding the role of endoscopic transmural drainage in the management of multiple pancreatic fluid collections. In this case report, we present the case of a 72-year-old male with three walled-off pancreatic fluid collections in the setting of acute necrotizing pancreatitis. The patient underwent simultaneous endoscopic ultrasound-assisted cyst gastrostomy and cyst duodenostomy and aggressive irrigation without index endoscopic necrosectomy of the three peripancreatic fluid collections. Significant improvement in the size of the fluid collections was seen on the computed tomography scan, as well as a remarkable immediate clinical improvement after 24 hours of the endoscopic intervention.

Proceedings from the Fissile Material Cut-off seminar in Stockholm

International Nuclear Information System (INIS)

Arbman, G.

1998-01-01

The Swedish Defence Research Establishment hosted an international expert seminar on the subject of verifying a prohibition of the production of fissile material for nuclear weapons purpose (cut-off) in Stockholm, June 3-5 1998. The objective of the seminar was to provide an opportunity for informal discussions among scientific and technical experts on various technical matters relating to the verification of a future Fissile Material Cut-off Treaty (FMCT). A stated aim of the seminar was to keep issues of scope to a minimum. Invited speakers and commentators were given an opportunity to present their views as written contributions. The present seminar proceedings are essentially the result of these views. In addition, short summaries of the discussions following each session are included. Although an attempt was made to be as complete and accurate as possible in reproducing these discussions, the editors apologise if some important points or statements have been omitted. If so, the main reason is that the documentation of the discussions were based on written notes, not taped recordings. Eight longer contributions have been separately indexed

Proceedings from the Fissile Material Cut-off seminar in Stockholm

Energy Technology Data Exchange (ETDEWEB)

Arbman, G. [ed.

1998-07-01

The Swedish Defence Research Establishment hosted an international expert seminar on the subject of verifying a prohibition of the production of fissile material for nuclear weapons purpose (cut-off) in Stockholm, June 3-5 1998. The objective of the seminar was to provide an opportunity for informal discussions among scientific and technical experts on various technical matters relating to the verification of a future Fissile Material Cut-off Treaty (FMCT). A stated aim of the seminar was to keep issues of scope to a minimum. Invited speakers and commentators were given an opportunity to present their views as written contributions. The present seminar proceedings are essentially the result of these views. In addition, short summaries of the discussions following each session are included. Although an attempt was made to be as complete and accurate as possible in reproducing these discussions, the editors apologise if some important points or statements have been omitted. If so, the main reason is that the documentation of the discussions were based on written notes, not taped recordings. Eight longer contributions have been separately indexed.

Measurement of current drive profile using electron cyclotron wave attenuation near the O-mode cut-off

International Nuclear Information System (INIS)

Fidone, I.

1991-01-01

A method for determining the radial profile of the lower-hybrid current drive in tokamaks uing electron-cyclotron attenuation of the O-mode for frequencies ω near the cut-off frequency is discussed. The basic idea is that for a given wave frequency, the cut-off plays the role of a spatial filter selecting a variable portion of the non-inductive current. It is shown that the incremental attenuation resulting from a small increase of ω displays specific features related to the current density near the cut-off point. Using the relation between the wave damping and the current density it is possible to determine the radial profile of the current drive from the wave attenuation measurements. A numerical application is also presented for plasma parameters in the reactor regime

Changes During Growth in Cell Wall Components of Berseem Clover Under Different Cutting Treatments in a Mediterranean Region

Directory of Open Access Journals (Sweden)

Giuditta De Santis

2007-09-01

Full Text Available Forage digestibility of berseem clover (Trifolium Alexandrinum L. is influenced by plant cell wall composition. This study was conducted to evaluate the effects of different cutting treatments on cell-wall components of the herbage and plant fractions in two Mediterranean berseem genotypes during growth and to examine the relationship between digestibility and cell wall components in these plant fractions. Cutting treatments were initiated at sixth internode elongation (A and early flowering (B and there was an uncut control treatment (C. Spring growth of genotypes of Egyptian (cv. Giza 10 and Italian (cv. Sacromonte origins was harvested in each of two years beginning 196 days after sowing and thereafter every 6 days (twelve harvests in total to measure cell wall components. Neutral detergent fibre (NDF, acid detergent fibre (ADF and acid detergent lignin (ADL concentrations were determined for leaf, stem, and total forage of each cultivar at each harvest. Without defoliation, NDF, ADF and ADL concentrations of herbage increased linearly to a maximum of 528, 375 and 84 g kg-1 DM, respectively, by 220 days after planting, when plant height reached maximum values, then plateaued until 257 days after planting. Plant parts differed in cell-wall concentration, with stems being of higher fibre components than leaves, in the two cutting treatments. Herbage and plant fraction fibre concentrations were negatively correlated with digestibility for all cutting treatments. Defoliation induced a reduction in fibre concentrations and plant height, although a rapid regrowth was observed after cutting, in both treatments A and B. However, delaying defoliation to the early flowering stage (B increased fibre components concentrations both at cutting time and during the growing season and significantly reduced the regrowth height. Conversely, plants cut at the sixth internode elongation (treatment A showed lower concentrations of fibre fractions than initiating

Swelling and hydraulic properties of Ca-bentonite for the buffer of a waste repository

International Nuclear Information System (INIS)

Lee, J.O.; Cho, W.J.; Kang, C.H.; Chun, K.S.

2001-01-01

Swelling and hydraulic tests were carried out to provide the information for the selection of buffer material in a radioactive waste repository. Ca-bentonite and de-ionized water were used for the tests. The swelling pressures of compacted bentonite were in the wide range of 0.7 Kg/cm 2 to 190.2 Kg/cm 2 , and they largely increased with an increase in the dry density and bentonite content. However, the swelling pressures decreased with increasing the initial water content and beyond about 12 wt.% of the initial water content, leveled off to a nearly constant value. The hydraulic conductivities were lower than 10 -11 m/s for the compacted bentonite with the dry density higher than 1.4 Mg/m 3 . They increased with increasing temperature in the range of 20 deg. C to 150 deg. C. (author)

Casimir effect in a d-dimensional flat spacetime and the cut-off method

International Nuclear Information System (INIS)

Svaiter, N.F.; Svaiter, B.F.

1989-01-01

The CasiMir efeect in a D-dimensional spacetime produced by a Hermitian massless scalar field in the presence of a pair of perfectly reflecting parallel flat plates is discussed. The exponential cut-off regularization method is employed. The regularized vacuum energy and the Casimir energy of this field are evaluated and a detailed analysis of the divergent terms in the regularized vacuum energy is carried out. The two-dimensional version of the Casimir effect is discussed by means of the same cut-off method. A comparison between the above method and the zeta function regularization procedure is presented in a way which gives the unification between these two methods in the present case. (author) [pt

Organophilic bentonites based on Argentinean and Brazilian bentonites: part 2: potential evaluation to obtain nanocomposites

Directory of Open Access Journals (Sweden)

L. B. Paiva

2012-12-01

Full Text Available This work describes the preparation of composites of polypropylene and organophilic bentonites based on Brazilian and Argentinean bentonites. During the processing of the samples in a twin screw microextruder, torque and pressures of the extruder were accompanied and the viscosity values were calculated. No significant changes in the torque, pressure and viscosity were found for composites prepared with different bentonites. The samples were characterized by XRD and TEM to evaluate the structure and dispersion of the organophilic bentonites. Composites with exfoliated, partially exfoliated and intercalated structures were obtained and correlations between the intrinsic properties of the sodium clays and organophilic bentonites and their influence on the composites were studied. The cation exchange capacity of the sodium bentonites and the swelling capacity of the organophilic bentonites were the most important properties to obtain exfoliated structures in composites. All bentonites showed the potential to obtain polymer nanocomposites, but the ones from Argentina displayed the best results.

Chronic kidney disease : Defining clinical cut-offs for albumin:creatinine ratio

NARCIS (Netherlands)

Bakker, Stephan J L

2013-01-01

Albuminuria is rapidly gaining recognition as a marker of the presence and of the progression of chronic kidney disease (CKD). In a new study, Naresh et al. attempt to define cut-off values for percentage change in urinary albumin:creatinine ratio that reflect changes in CKD status rather than

Establishing Streptomycin Epidemiological Cut-Off Values for Salmonella and Escherichia coli

DEFF Research Database (Denmark)

Migura, Lourdes Garcia; Sunde, Marianne; Karlsmose, Susanne

2011-01-01

This study was conducted to elucidate the accuracy of the current streptomycin epidemiological cut-off value (ECOFF) for Escherichia coli and Salmonella spp. A total of 236 Salmonella enterica and 208 E. coli isolates exhibiting MICs between 4 and 32 mg/L were selected from 12 countries. Isolates...

Prevalensi Sarkopenia pada Lansia di Komunitas (Community Dwelling berdasarkan Dua Nilai Cut-off Parameter Diagnosis

Directory of Open Access Journals (Sweden)

Vitriana

2016-09-01

Full Text Available Sarcopenia, aging muscle mass loss, and function syndromes can lead to decreased quality of life and increased elderly mortality. The availability of various screening methods and operational definitions in different studies has produced different findings of sarcopenia prevalence. The purpose of this study was to discover the prevalence of sarcopenia in Indonesian community-dwelling elderly based on muscle mass measured by bioimpedance analysis, handgrip strength using hand dynamometer, and physical performance based on six minutes walking test with two different cut-off point parameters of sarcopenia, i.e. the cut-off point recommended by Asian Working Group for Sarcopenia (AWGS and the cut-off point based on the reference used in Taiwan elderly population reference due to the lack of references for Indonesian elderly population. A cross-sectional study was conducted to 229 participants (71 men and 158 women from the community-dwelling elderly population between August and December 2014 in Bandung and Jatinangor. The results of the study showed that the sarcopenia prevalence in this study based on AWGS was 9.1% (7.4% in men and 1.7% in women while the prevalence based on the Taiwan reference revealed a prevalence of 40.6% (20.1% in men and 20.5% in women. This highly different prevalences shows the importance of defining a specific cut-off point for elderly population in community-dwelling Indonesia to get a more accurate sarcopenia prevalence.

Equipment for deployment of canisters with spent nuclear fuel and bentonite buffer in horizontal holes

International Nuclear Information System (INIS)

Henttonen, V.; Suikki, M.

1992-08-01

The study presents the predesign of equipment for the deployment of canisters in long horizontal holes. The canisters are placed in the centre of the hole and are surrounded by a bentonite buffer. In thE study the canisters are assumed to have a diameter of 1.6 m and a length of 5.9 m, including the hemispherical ends. Their total weight is 60 tonnes. The bentonite buffer after homogenization is 400 mm thick, making a total package diameter of 2.4 m. The deployment system consists of four wagons for handling The canisters and the bentonite blocks. To ensure safe emplacement, every part is installed separately in its final position. This also makes it possible to use small clearances between the canisters and the bentonite blocks and between the blocks and the rock wall. With small clearances, backfilling can be avoided. Another basic design idea is that the wagons are equipped with wheels, which are in direct contact with the rock walls. Thus, rails, which have to be removed as the deployment progresses, are unnecessary. To minimize the time taken for deploying one canister, the wagons are designed so that only three trips from the service area to the deposit area are needed. Due to the radiation in the vicinity of the canisters, the wagons have to be teleoperated

Equipment for deployment of canisters with spent nuclear fuel and bentonite buffer in horisontal holes

International Nuclear Information System (INIS)

Henttonen, V.; Suikki, M.

1992-06-01

This study presents the predesign of equipment for the deployment of canisters in long horizontal holes. The canisters are placed in the centre of the hole and are surrounded by a bentonite buffer. In this study the canisters are assumed to have a diameter of 1.6 m and a length of 5.9 m, including the hemispherical ends. Their total weight is 60 tonnes. The bentonite buffer after homogenization is 400 mm thick, making a total package diameter of 2.4 m. The deployment system consists of four wagons for handling the canisters and the bentonite blocks. To ensure safe emplacement, every part is installed separately in its final position. This also makes it possible to use small clearances between the canisters and the bentonite blocks and between the blocks and the rock wall. With small clearances, backfilling can be avoided. Another basic design idea is that the wagons are equipped with wheels, which are in direct contact with the rock walls. Thus, rails, which have to be removed as the deployment progresses, are unnecessary. To minimize the time taken for deploying one canister, the wagons are designed so that only three trips from the service area to the deposit area are needed. Due to the radiation in the vicinity of the canisters, the wagons have to be teleoperated. (au)

Secondary proton production at small atmospheric depths as a function of the geomagnetic cut-off

Energy Technology Data Exchange (ETDEWEB)

Papini, P. [Florence Univ. (Italy)]|[INFN, Florence (Italy); Grimani, C. [Perugia Univ. (Italy)]|[INFN, Perugia (Italy); Stephens, S.A. [Tata Institute of Fundamental Research, Bombay (International Commission on Radiation Units and Measurements)

1995-09-01

A detailed calculation of the energy spectrum of secondary protons in the atmosphere is being carried out in the energy range 20 MeV - 40 GeV. In this calculation, it is taken into account all processes leading to the production of secondary protons as a function of the atmospheric depth has been calculated using all relevant energy loss processes. In this paper, it is examine the effect of the geomagnetic cut-off on the spectral shape of secondary protons specially at energies below the geomagnetic cut-off for small atmospheric depths.

Secondary proton production at small atmospheric depths as a function of the geomagnetic cut-off

International Nuclear Information System (INIS)

Papini, P.; Grimani, C.; Stephens, S.A.

1995-01-01

A detailed calculation of the energy spectrum of secondary protons in the atmosphere is being carried out in the energy range 20 MeV - 40 GeV. In this calculation, it is taken into account all processes leading to the production of secondary protons as a function of the atmospheric depth has been calculated using all relevant energy loss processes. In this paper, it is examine the effect of the geomagnetic cut-off on the spectral shape of secondary protons specially at energies below the geomagnetic cut-off for small atmospheric depths

One-dimensional contaminant transport model for the design of soil-bentonite slurry walls

International Nuclear Information System (INIS)

Khandelwal, A.; Rabideau, A.; Su, J.

1997-01-01

A user oriented computer model (TRANS1D) was developed for application to the analysis and design of vertical soil-bentonite barriers. TRANS1D is a collection of analytical and numerical solutions to the one dimensional advective-dispersive-reactive (ADR) equation. The primary objective in developing TRANS1D was to enable the designer of a barrier system to evaluate the potential system performance with respect to contaminant transport, without performing difficult and time consuming field or laboratory experiments. Several issues related to model application are discussed, including identification of governing transport processes, specification of boundary conditions, and parameter estimation. Model predictions are compared with the results of laboratory column experiments conducted with soil bentonite barrier material under diffusion-dominated conditions. Good agreement between model calibrations and experimental results was noted, with calibrated diffusion coefficients for organic contaminants consistent with literature values

Fe-bentonite. Experiments and modelling of the interactions of bentonites with iron

Energy Technology Data Exchange (ETDEWEB)

Herbert, Horst-Juergen; Xie, Mingliang [Gesellschaft fuer Anlagen- und Reaktorsicherheit mbH (GRS), Koeln (Germany); Kasbohm, Joern; Lan, Nguyen T. [Greifswald Univ. (Germany); Hoang Thi Minh Thao [Hanoi Univ. of Science (Viet Nam)

2011-11-15

The main objectives of this study were to enhance the understanding of the interactions of bentonites with steel containers in the near field of a repository in salt formations and to determine missing experimental thermo-hydraulical-chemical and mineralogical data needed for the THC modelling of the interactions of bentonites with iron. At the beginning of this project a literature review helped to clarify the state of the art regarding the above mentioned objectives prior to the start of the experimental work. In the following experimental programme the hydraulic changes in the pore space of compacted MX80 bentonites containing metallic iron powder and in contact with three solutions of different ionic strength containing different concentrations of Fe{sup 2+} have been investigated. The alterations of MX80 and several other bentonites have been assessed in contact with the low ionic strength Opalinus Clay Pore Water (OCPW) and the saturated salt solutions NaCl solution and IP21 solution. Under repository relevant boundary conditions we determined on compacted MX80 samples with the raw density of 1.6 g/cm{sup 3} simultaneously interdependent properties like swelling pressures, hydraulic parameters (permeabilities and porosities), mineralogical data (changes of the smectite composition and iron corrosion products), transport parameters (diffusion coefficients) and thermal data (temperature dependent reaction progresses). The information and data resulting from the experiments have been used in geochemical modelling calculations and the existing possibilities and limitations to simulate these very complex near field processes were demonstrated. The main conclusion of this study is that the alteration of bentonites in contact with iron is accentuated and accelerated. Alterations in contact with solutions of different ionic strength identified by the authors in previous studies were found be much more intensive in contact with metallic iron and at elevated

Derivation of the cut-off length from the quantum quadratic enhancement of a mass in vacuum energy constant Lambda

Science.gov (United States)

Fukushima, Kimichika; Sato, Hikaru

2018-04-01

Ultraviolet self-interaction energies in field theory sometimes contain meaningful physical quantities. The self-energies in such as classical electrodynamics are usually subtracted from the rest mass. For the consistent treatment of energies as sources of curvature in the Einstein field equations, this study includes these subtracted self-energies into vacuum energy expressed by the constant Lambda (used in such as Lambda-CDM). In this study, the self-energies in electrodynamics and macroscopic classical Einstein field equations are examined, using the formalisms with the ultraviolet cut-off scheme. One of the cut-off formalisms is the field theory in terms of the step-function-type basis functions, developed by the present authors. The other is a continuum theory of a fundamental particle with the same cut-off length. Based on the effectiveness of the continuum theory with the cut-off length shown in the examination, the dominant self-energy is the quadratic term of the Higgs field at a quantum level (classical self-energies are reduced to logarithmic forms by quantum corrections). The cut-off length is then determined to reproduce today's tiny value of Lambda for vacuum energy. Additionally, a field with nonperiodic vanishing boundary conditions is treated, showing that the field has no zero-point energy.

Mixing conditions in application of bentonite grouting to radioactive waste disposal

International Nuclear Information System (INIS)

Kobayakawa, Hiroaki; Ito, Hiroshi

2007-01-01

The purpose of this study was to understand the flow properties and permeability of bentonite grout with NaCl added, using laboratory tests, and to clarify the mixing conditions of bentonite as a material. Given that the required permeability of clay grout is 10 -9 (m/s), the combination of grout (W/B) becomes 6 or less. The viscosity of the grout was measured, and because the viscosity was higher than the thickest cement milk on dam grouting, it was found that grout with a W/B of less than 10 was difficult to inject into rock joints. We then added NaCl to grout with a W/B is 6, and its viscosity decreased as the amount of NaCl increased. A grout of viscosity able to be injected into rock joints was achieved by adding NaCl in a density higher than 'W:NaCl=40:1'. Next, the permeability of a bentonite suspension with NaCl was examined using the falling head permeability test. Testing the sample 'B:W:NaCl=20:20:1' for 10 days revealed that the initial permeability 10 -8 (m/s) decreased to 10 -10 - 10 -11 (m/s). These results showed that a suspension to inject into rock joints could be made by adding NaCl, and clarified that permeation of groundwater into the suspension causes a decline in permeability. (author)

Revisiting AdS/CFT at a finite radial cut-off

Energy Technology Data Exchange (ETDEWEB)

Mandal, Gautam; Nayak, Pranjal [Department of Theoretical Physics,Tata Institute of Fundamental Research, Mumbai 400005 (India)

2016-12-22

We revisit AdS/CFT at a finite radial cut-off, specifically in the context of double trace perturbations, O{sub n}= O(x)(∂{sup 2}){sup n}O(x), with arbitrary powers n. As well-known, the standard GKPW prescription, applied to a finite radial cut-off, leads to contact terms in correlators. de Haro et al. http://dx.doi.org/10.1007/s002200100381 introduced bulk counterterms to remove these. This prescription, however, yields additional terms in the correlator corresponding to spurious double trace deformations. Further, if we view the GKPW prescription coupled with the prescription in http://dx.doi.org/10.1007/s002200100381, in terms of a boundary wavefunction, we find that it is incompatible with radial Schrödinger evolution (in the spirit of holographic Wilsonian RG). We consider a more general wavefunction satisfying the Schrödinger equation, and find that generically such wavefunctions generate both (a) double trace deformations and (b) contact terms. However, we find that there exist special choices of these wavefunctions, amounting to a new AdS/CFT prescription at a finite cut-off, so that both (a) and (b) are removed and we obtain a pure power law behaviour for the correlator. We compare these special wavefunctions with a specific RG scheme in field theory. We give a geometric interpretation of these wavefunctions; these correspond to some specific smearing of boundary points in the Witten diagrams. We present a comprehensive calculation of exact double-trace beta-functions for all couplings O{sub n} and match with a holographic computation using the method described above. The matching works with a mapping between the field theory and bulk couplings; such a map is highly constrained because the beta-functions are quadratic and exact on both sides. Our discussions include a generalization of the standard double-trace Wilson-Fisher flow to the space of the infinite number of couplings.

Insulin Resistance Distribution and Cut-Off Value in Koreans from the 2008-2010 Korean National Health and Nutrition Examination Survey

Science.gov (United States)

Yun, Kyung-Jin; Han, Kyungdo; Kim, Mee Kyoung; Park, Yong-Moon; Baek, Ki-Hyun; Song, Ki-Ho; Kwon, Hyuk-Sang

2016-01-01

Background We sought to identify the distribution and cut-off value of the ‘homeostasis model assessment of insulin resistance’ (HOMA-IR) according to gender and menopausal status for metabolic syndrome in Koreans. Methods Data were from the Korean National Health and Nutrition Examination Survey in 2008–2010. The subjects included adults aged 20 years or older. We excluded participants who had diabetes or fasting serum glucose ≥ 7 mmol/L. Finally, 11,121 subjects (4,911 men, 3,597 premenopausal women, 2,613 postmenopausal women) were enrolled. The modified Adult Treatment Panel III criteria were used to define metabolic syndrome. Results The mean HOMA-IR was 2.11 (2.07–2.15) for men, 2.0 (1.97–2.04) for premenopausal women, and 2.14 (2.2–2.19) for postmenopausal women. The first cut-off values in men, premenopausal women, and postmenopausal women were 2.23 (sensitivity 70.6%, specificity 66.9%), 2.39 (sensitivity 72.3%, specificity 76.4%), and 2.48 (sensitivity 51.9%, specificity 80.2%), respectively. Based on the first HOMA-IR cut-off value, the prevalence of metabolic syndrome was 22.9% in men, 13.7% in premenopausal women, and 51.6% in postmenopausal women. The second cut-off value was around 3.2 in all three groups. Based on the second HOMA-IR cut-off value, the prevalence of metabolic syndrome was 50.8% in men, 42.5% in premenopausal women, and 71.6% in postmenopausal women. Conclusion In conclusion, the first cut-off values for HOMA-IR were 2.2–2.5 and the second cut-off value was 3.2 in Korea. The distribution of HOMA-IR showed differences according to gender and menopausal status. When we apply HOMA-IR, we should consider gender, menopausal status, and the prevalence of metabolic syndrome. PMID:27128847

Porewater chemistry in compacted bentonite

Energy Technology Data Exchange (ETDEWEB)

Muurinen, A.; Lehikoinen, J. [VTT Chemical Technology, Espoo (Finland)

1999-03-01

In this study, the porewater chemistry in compacted bentonite, considered as an engineered barrier in the repository of spent fuel, has been studied in interaction experiments. Many parameters, like the composition and density of bentonite, composition of the solution, bentonite-to-water ratio (B/W), surrounding conditions and experimental time have been varied in the experiments. At the end of the interaction the equilibrating solution, the porewaters squeezed out of the bentonite samples, and bentonites themselves were analyzed to give information for the interpretation and modelling of the interaction. Equilibrium modelling was performed with the HYDRAQL/CE computer code 33 refs.

Clinically Relevant Cut-off Points for the Diagnosis of Sarcopenia in Older Korean People.

Science.gov (United States)

Choe, Yu-Ri; Joh, Ju-Youn; Kim, Yeon-Pyo

2017-11-09

The optimal criteria applied to older Korean people have not been defined. We aimed to define clinically relevant cut-off points for older Korean people and to compare the predictive validity with other definitions of sarcopenia. Nine hundred and sixteen older Koreans (≥65 years) were included in this cross-sectional observational study. We used conditional inference tree analysis to determine cut-off points for height-adjusted grip strength (GS) and appendicular skeletal muscle mass (ASM), for use in the diagnosis of sarcopenia. We then compared the Korean sarcopenia criteria with the Foundation for the National Institutes of Health and Asian Working Group for Sarcopenia criteria, using frailty, assessed with the Korean Frailty Index, as an outcome variable. For men, a residual GS (GSre) of ≤ 0.25 was defined as weak, and a residual ASM (ASMre) of ≤ 1.29 was defined as low. Corresponding cut-off points for women were a GSre of ≤ 0.17 and an ASMre of ≤ 0.69. GSre and ASMre values were adjusted for height. In logistic regression analysis with new cut-off points, the adjusted odds ratios for pre-frail or frail status in the sarcopenia group were 3.23 (95% confidence interval [CI] 1.33-7.83) for the men and 1.74 (95% CI 0.91-3.35) for the women. In receiver operating characteristic curve analysis, the unadjusted area under the curve for Korean sarcopenia criteria in men and women were 0.653 and 0.608, respectively (p sarcopenia in older Korean people. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effect of Abutment Modification and Cement Type on Retention of Cement-Retained Implant Supported Crowns

Science.gov (United States)

Farzin, Mitra; Torabi, Kianoosh; Ahangari, Ahmad Hasan; Derafshi, Reza

2014-01-01

Objective: Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations. Materials and Method: Two prefabricated abutments were attached to their corresponding analogs and embedded in an acrylic resin block. The first abutment (control group) was left intact without any modifications. The screw access channel for the first abutment was completely filled with composite resin. In the second abutment, (test group) the axial wall was partially removed to form an abutment with 3 walls. Wax models were made by CAD/CAM. Ten cast copings were fabricated for each abutment. The prepared copings were cemented on the abutments by Temp Bond luting agent under standardized conditions (n=20). The assemblies were stored in 100% humidity for one day at 37°C prior to testing. The cast crown was removed from the abutment using an Instron machine, and the peak removal force was recorded. Coping/abutment specimens were cleaned after testing, and the testing procedure was repeated for Dycal luting agent (n=20). Data were analyzed with two- way ANOVA (α=0.05). Results: There was no significant difference in the mean transformed retention (Ln-R) between intact abutments (4.90±0.37) and the abutments with 3 walls (4.83±0.25) using Dycal luting agent. However, in TempBond group, the mean transformed retention (Ln-R) was significantly lower in the intact abutment (3.9±0.23) compared to the abutment with 3 walls (4.13±0.33, P=0.027). Conclusion: The retention of cement-retained implant restoration can be improved by the type of temporary cement used. The retention of cast crowns cemented to implant abutments with TempBond is influenced by the wall removal. PMID:25628660

Effect of abutment modification and cement type on retention of cement-retained implant supported crowns.

Directory of Open Access Journals (Sweden)

Mitra Farzin

2014-06-01

Full Text Available Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations.Two prefabricated abutments were attached to their corresponding analogs and embedded in an acrylic resin block. The first abutment (control group was left intact without any modifications. The screw access channel for the first abutment was completely filled with composite resin. In the second abutment, (test group the axial wall was partially removed to form an abutment with 3 walls. Wax models were made by CAD/CAM. Ten cast copings were fabricated for each abutment. The prepared copings were cemented on the abutments by Temp Bond luting agent under standardized conditions (n=20. The assemblies were stored in 100% humidity for one day at 37°C prior to testing. The cast crown was removed from the abutment using an Instron machine, and the peak removal force was recorded. Coping/abutment specimens were cleaned after testing, and the testing procedure was repeated for Dycal luting agent (n=20. Data were analyzed with two- way ANOVA (α=0.05.There was no significant difference in the mean transformed retention (Ln-R between intact abutments (4.90±0.37 and the abutments with 3 walls (4.83±0.25 using Dycal luting agent. However, in TempBond group, the mean transformed retention (Ln-R was significantly lower in the intact abutment (3.9±0.23 compared to the abutment with 3 walls (4.13±0.33, P=0.027.The retention of cement-retained implant restoration can be improved by the type of temporary cement used. The retention of cast crowns cemented to implant abutments with TempBond is influenced by the wall removal.

Efficient Closed Form Cut-Off Planes and Propagation Planes Characteristics for Dielectric Slab Loaded Boundary Value Problems

OpenAIRE

Zafar, Junaid

2012-01-01

The geometrical relationship between the cut-off and propagating planes of any waveguide system is a prerequisite for any design process. The characterization of cut-off planes and optimisation are challenging for numerical methods, closed-form solutions are always preferred. In this paper Maxwells coupled field equations are used to characterise twin E-plane and H-plane slab loaded boundary value problems. The single mode bandwidths and dispersion characteristics of these structures are pres...

[Analysis of Cut-off Value in Screening of Thalassemia by Capillary Hemoglobin Electrophoresis for Pregnant Women from Shenzhen Region of China].

Science.gov (United States)

Huo, Mei; Wu, Wen-Yuan; Liu, Mei; Gan, Zhi-Biao; Mao, Wei-Yu; Lin, Rong-Yao; Liu, Ai-Qin; He, Gui-Rong

2016-04-01

To investigate the cut-off value in screening of thalassemia in pregnant women from Shenzhen region by capillary hemoglobin electrophoresis. The data of capillary hemoglobin electrophoresis and genetic diagnosis of thalassemia from 2122 examined prenatal women were retrospectively analyzed. Capillary hemoglobin electrophoresis and α-, β- genetic diagnosis of thalassemia were carried out for every woman. Hemoglobin electrophoresis was performed using Capillarys 2 full-automated electrophoresis instrument. Gap polymerase chain reaction and reverse dot blot were used for genetic diagnosis of thalassemia genotyping test. The cut-off value in screening of thalassemia was determined by receiver operating characteristic curve and next to analyze the value of HbA2 and HbF in screening of thalassemia using the decided cut-off value. The areas under the curve (AUC(Roc)) of HbA2 for diagnosis of α-, β- thalassemia were 0.75 and 0.981 respectively, and the AUC(Roc) of HbF for diagnosis of β-thalassemia was 0.787. When HbA2 ≤ 2.55 was taken as the cut-off value of HbA2 for diagnosis of α-thalassemia, the sensitivity, specificity, positive likelihood ratio (LR(+)) and negative likelihood ratio (LR(-)) were 89.5%, 54.8%, 1.98, 0.19 respectively. When HbA2 ≥3.9 was taken as the cut off value of HbA2 for diagnosis of β-thalassemia, the sensitivity, specificity, LR(+) and LR(-) were 96.1%, 99.8% 480.5, 0.04 respectively. When HbF ≥0.75 was taken as the cut off value of HbF for diagnosis of β-thalassemia, the sensitivity, specificity, LR(+) and LR(-) were 83.6%, 61.8% respectively. The cut-off value in screening of thalassemia by capillarys 2 full automated electrophoresis instrument is different from that of the traditional method of hemoglobin electrophoresis, such as cellulose acetate membrane electrophoresis and agarose gel electrophoresis. Each laboratory should establish their own respective cut off value.

Bentonite erosion - Laboratory studies

International Nuclear Information System (INIS)

Jansson, Mats

2010-01-01

Document available in extended abstract form only. Bentonite clay is proposed as buffer material in the KBS-3 concept of storing spent nuclear fuel. Since the clay is plastic it will protect the canisters containing the spent fuel from movements in the rock. Furthermore, the clay will expand when taking up water, become very compact and hence limit the transport of solutes to and from the canister to only diffusion. The chemical stability of the bentonite barrier is of vital importance. If much material would be lost the barrier will lose its functions. As a side effect, lots of colloids will be released which may facilitate radionuclide transport in case of a breach in the canister. There are scenarios where during an ice age fresh melt water may penetrate down to repository depths with relatively high flow rates and not mix with older waters of high salinity. Under such conditions bentonite colloids will be more stable and there is a possibility that the bentonite buffer would start to disperse and bentonite colloids be carried away by the passing water. This work is a part of a larger project called Bentonite Erosion, initiated and supported by SKB. In this work several minor experiments have been performed in order to investigate the influence of for instance di-valent cations, gravity, etc. on the dispersion behaviour of bentonite and/or montmorillonite. A bigger experiment where the real situation was simulated using an artificial fracture was conducted. Two Plexiglas slabs were placed on top of each other, separated by plastic spacers. Bentonite was placed in a container in contact with a fracture. The bentonite was water saturated before deionized water was pumped through the fracture. The evolution of the bentonite profile in the fracture was followed visually. The eluate was collected in five different slots at the outlet side and analyzed for colloid concentration employing Photon Correlation Spectroscopy (PCS) and a Single Particle Counter (SPC). Some

The dischargeable cut-off score of Oswestry Disability Index (ODI) in the inpatient care for low back pain with disability.

Science.gov (United States)

Park, Sang-Won; Shin, Ye-Sle; Kim, Hye-Jin; Lee, Jin-Ho; Shin, Joon-Shik; Ha, In-Hyuk

2014-10-01

The admission due to low back pain (LBP) became prevalent cause of international economic losses. Since LBP patients with disability are often subject to inpatient care, it is important to determine the appropriate time of discharge. The purpose of this study is to set the cut-off value of appropriate Oswestry Disability Index (ODI) at the time of discharge. Of 1,394 LBP patients admitted in hospital specialized in spinal disease, 774 eligible patients with disability were included in this study. And several clinical variables including numerical rating score, ODI, satisfaction level were observed during the hospital stay. We considered satisfaction level as an important factor for discharge, categorized patients into satisfied group and dissatisfied group. Through the statistical analysis, appropriate factor for determining dischargeable patients satisfied with their current condition and its cut-off value of ODI were found. And proper predictors for the cut-off value were extracted statistically and logically from a pool of several clinical indexes. The ODI at the time of discharge was most accurate in determining dischargeable patients. The cut-off value of ODI was 30. Predictors were ODI questions 4 and 6. We set the cut-off value of dischargeable ODI for LBP inpatient with disability and found its predictor.

Age-related differences in recommended anthropometric cut-off point validity to identify cardiovascular risk factors in ostensibly healthy women.

Science.gov (United States)

Subramoney, Sreevidya; Björkelund, Cecilia; Guo, Xinxin; Skoog, Ingmar; Bosaeus, Ingvar; Lissner, Lauren

2014-12-01

To investigate validity of widely recommended anthropometric and total fat percentage cut-off points in screening for cardiovascular risk factors in women of different ages. A population-based sample of 1002 Swedish women aged 38, 50, 75 (younger, middle-aged and elderly, respectively) underwent anthropometry, health examinations and blood tests. Total fat was estimated (bioimpedance) in 670 women. Sensitivity, specificity of body mass index (BMI; ≥25 and ≥30), waist circumference (WC; ≥80 cm and ≥88 cm) and total fat percentage (TF; ≥35%) cut-off points for cardiovascular risk factors (dyslipidaemias, hypertension and hyperglycaemia) were calculated for each age. Cut-off points yielding high sensitivity together with modest specificity were considered valid. Women reporting hospital admission for cardiovascular disease were excluded. The sensitivity of WC ≥80 cm for one or more risk factors was ~60% in younger and middle-aged women, and 80% in elderly women. The specificity of WC ≥80 cm for one or more risk factors was 69%, 57% and 40% at the three ages (p < .05 for age trends). WC ≥80 cm yielded ~80% sensitivity for two or more risk factors across all ages. However, specificity decreased with increasing age (p < .0001), being 33% in elderly. WC ≥88 cm provided better specificity in elderly women. BMI and TF % cut-off points were not better than WC. Validity of recommended anthropometric cut-off points in screening asymptomatic women varies with age. In younger and middle-age, WC ≥80 cm yielded high sensitivity and modest specificity for two or more risk factors, however, sensitivity for one or more risk factor was less than optimal. WC ≥88 cm showed better validity than WC ≥80 cm in elderly. Our results support age-specific screening cut-off points for women. © 2014 the Nordic Societies of Public Health.

X-ray Spectral Survey of WGACAT Quasars, II: Optical and Radio Properties of Quasars with Low Energy X-ray Cut-offs

OpenAIRE

Elvis, Martin; Fiore, Fabrizio; Giommi, Paolo; Padovani, Paolo

1997-01-01

We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high delta-v candidate systems. Two other cut-off quasars show reddening associated with the quasar. We conclude that absorption is highly likely to be the cause of the X-ray cut-offs, and that the abso...

Cut-off values of distal forearm bone density for the diagnosis of ...

African Journals Online (AJOL)

Background: The objective of this study was to establish a triage cut-off point or threshold for peripheral bone mineral density (BMD), applicable to black postmenopausal women, and that could be used as a screening method to differentiate between women with normal BMD, and those with possible central osteoporosis.

Transport and leaching of technetium and uranium from spent UO2 fuel in compacted bentonite clay

International Nuclear Information System (INIS)

Ramebaeck, H.; Albinsson, Y.; Skaalberg, M.; Eklund, U.B.; Kjellberg, L.; Werme, L.

2000-01-01

The transport properties of Tc and U in compacted bentonite clay and the leaching behaviour of these elements from spent nuclear fuel in the same system were investigated. Pieces of spent UO 2 fuel were embedded in bentonite clay (ρ d =2100 kg/m 3 ). A low saline synthetic groundwater was used as the aqueous phase. After certain experimental times, the bentonite clay was cut into 0.1 mm thick slices, which were analysed for their content of Tc and U. Measurements were made using inductively coupled plasma mass spectrometry. Tc analysis comprised chemical separation. The analysis of U was done by means of detecting 236 U, since the natural content of U in bentonite clay made it impossible to distinguish between U originating from the fuel and the clay. The influence of different additives mixed into the clay was studied. The results showed an influence on both transport and leaching behaviour when metallic Fe was mixed into the clay. This indicates that Tc and U are reduced to their lower oxidation states as a result of this additive

On the Cut-off Point for Combinatorial Group Testing

DEFF Research Database (Denmark)

Fischer, Paul; Klasner, N.; Wegener, I.

1999-01-01

is answered by 1 if Q contains at least one essential object and by 0 otherwise. In the statistical setting the objects are essential, independently of each other, with a given probability p combinatorial setting the number k ... group testing is equal to p* = 12(3 - 5), i.e., the strategy of testing each object individually minimizes the average number of queries iff p >= p* or n = 1. In the combinatorial setting the worst case number of queries is of interest. It has been conjectured that the cut-off point of combinatorial...

Tentative Colistin Epidemiological Cut-Off Value for Salmonella spp

DEFF Research Database (Denmark)

Agersø, Yvonne; Torpdahl, Mia; Zachariasen, Camilla

2012-01-01

. Interestingly, Salmonella Dublin and Salmonella Enteritidis belong to the same O-group (O:1, 9,12), suggesting that surface lipopolysaccharides (LPS) of the cell (O-antigen) play a role in colistin susceptibility. The epidemiological cut-off value of >2 mg/L for colistin suggested by European Committee...... on Antimicrobial Susceptibility Testing (EUCAST) is placed inside the distribution for both Salmonella Dublin and Salmonella Enteritidis. All tested Salmonella Dublin isolates, regardless of MIC colistin value, had identical pmrA and pmrB sequences. Missense mutations were found only in pmrA in one Salmonella...

Epidemiological cut-off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol

DEFF Research Database (Denmark)

Smith, P.; Endris, R.; Kronvall, G.

2016-01-01

-1 for florfenicol, ≤0.025 mg L-1 for oxolinic acid (OXO), ≤0.125 mg L-1 for oxytetracycline and ≤20 (1/19) mg L-1 for trimethoprim/sulphamethoxazole. For ampicillin and amoxicillin, the majority of putative wild-type observations were 'off scale', and therefore, statistically valid cut-off values...

Body mass index and waist-to-height ratio cut-offs as predictors of high blood pressure in adolescents

Directory of Open Access Journals (Sweden)

Kurnia Febriana

2015-04-01

Full Text Available Background: Obesity is associated with increased risk for high blood pressure (BP. Although a routine BP measurement is indicated for all children visiting pediatric practice, recognition of children particularly at risk may save times. The aim of this study was to assess the cut-off point for body mass index (BMI and waist-to-height ratio (WHtR to predict high BP in adolescents. Methods: We conducted a cross-sectional study on 928 children aged 11 to 16 years in Yogyakarta. BP were measured using standard technique described by The Fourth Report on The Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. BMI was adjusted for age and sex using the WHO 2007 growth reference. WHtR was ratio of waist circumference related to height in centimeters. Receiver operating characteristic (ROC curves were used to estimate the best cut-offs. Results: The best cut-off point for BMI-for-age Z-score (BMIZ to predict high BP was 0.51 with sensitivity and specificity of 82% (95% CI = 78-86 and 76% (95% CI = 67-78 for systolic BP and sensitivity and specificity of 82% (95% CI = 78-86 and 72% (95% CI = 68-76 for diastolic BP. The best cut-off point for WHtR was 0.45, with sensitivity of 76% (95% CI = 67-78 and specificity of 74% (95% CI = 71-79 for systolic BP and sensitivity of 76% (95% CI = 72-80 and specificity of 70% (95% CI = 61-75 for diastolic BP.Conclusion: BMIZ of 0.51 and WHtR of 0.45 are the best cut-off point to predict high BP in adolescents.

Poverty and cutting off the power: Evaluation of the social contract of the Electricite de France

International Nuclear Information System (INIS)

Wodon, Q. T.

2003-01-01

Measures put in place by the French Electric Utility, Electricite de France (EDF) to assist those in default of payment of their electricity bills are evaluated. When introduced in 1996, it was expected that the new measures would reduce the necessity of cutting off power to the poor by one third. Notwithstanding these expectations and some progress in reducing the rate of power cut-off, the number of instances where service was denied, has risen. The evaluation is based on the annual survey of poor clients of the EDF undertaken by the Polling Institute Lavialle. The annual survey concerns itself chiefly with the attitude towards the service and the quality of dialogue between the Utility and its clients. The analysis resulted in three conclusions: (1) EDF appears to make progress in dealing with the problem based on evidence of higher client satisfaction and lower rate of cutting off power; (2) there is evidence of important beneficial changes in the policies of local EDF centres; and (3) there is noticeable evidence of improved coordination with social services agencies and higher quality of information made available; both these factors should contribute to higher client satisfaction. In general, EDF is to be congratulated for their efforts to date, for commissioning the survey and for participating in the evaluation. Nevertheless, in France the instances of cutting off electricity to poor households is still a fact of life, despite the commitment and the new measures put in place by EDF. 21 refs., 7 tabs., 1 fig

Immobilization of strontium and cesium in intermediate-level liquid wastes by solidification in cements

International Nuclear Information System (INIS)

Rudolph, G.; Koester, R.

1979-01-01

An accelerated leach test at elevated temperature has been developed which gives intercomparable results within one day. It is very useful for product quality control at large throughputs. Using this test, it has been shown that cesium leachabilities from cement products containing a simulated waste typical of fuel reprocessing plants can be reduced by addition of a bentonite. Addition of barium silicate hydrate retards strontium leaching in these cements. Leach rates in tap water and in salt brine are lower than in distilled water and sodium chloride solution

Defining Glaucomatous Optic Neuropathy from a Continuous Measure of Optic Nerve Damage - The Optimal Cut-off Point for Risk-factor Analysis in Population-based Epidemiology

NARCIS (Netherlands)

Ramdas, Wishal D.; Rizopoulos, Dimitris; Wolfs, Roger C. W.; Hofman, Albert; de Jong, Paulus T. V. M.; Vingerling, Johannes R.; Jansonius, Nomdo M.

2011-01-01

Purpose: Diseases characterized by a continuous trait can be defined by setting a cut-off point for the disease measure in question, accepting some misclassification. The 97.5th percentile is commonly used as a cut-off point. However, it is unclear whether this percentile is the optimal cut-off

Rise time of proton cut-off energy in 2D and 3D PIC simulations

Science.gov (United States)

Babaei, J.; Gizzi, L. A.; Londrillo, P.; Mirzanejad, S.; Rovelli, T.; Sinigardi, S.; Turchetti, G.

2017-04-01

The Target Normal Sheath Acceleration regime for proton acceleration by laser pulses is experimentally consolidated and fairly well understood. However, uncertainties remain in the analysis of particle-in-cell simulation results. The energy spectrum is exponential with a cut-off, but the maximum energy depends on the simulation time, following different laws in two and three dimensional (2D, 3D) PIC simulations so that the determination of an asymptotic value has some arbitrariness. We propose two empirical laws for the rise time of the cut-off energy in 2D and 3D PIC simulations, suggested by a model in which the proton acceleration is due to a surface charge distribution on the target rear side. The kinetic energy of the protons that we obtain follows two distinct laws, which appear to be nicely satisfied by PIC simulations, for a model target given by a uniform foil plus a contaminant layer that is hydrogen-rich. The laws depend on two parameters: the scaling time, at which the energy starts to rise, and the asymptotic cut-off energy. The values of the cut-off energy, obtained by fitting 2D and 3D simulations for the same target and laser pulse configuration, are comparable. This suggests that parametric scans can be performed with 2D simulations since 3D ones are computationally very expensive, delegating their role only to a correspondence check. In this paper, the simulations are carried out with the PIC code ALaDyn by changing the target thickness L and the incidence angle α, with a fixed a0 = 3. A monotonic dependence, on L for normal incidence and on α for fixed L, is found, as in the experimental results for high temporal contrast pulses.

[Research progress on the clinical value of Ki-67 in breast cancer and its cut-off definition].

Science.gov (United States)

Chen, Qing; Wu, Kejin

2015-08-01

Ki-67 has an important application value in clinical practice. However, it is still a little tough in clinical application because of the debate on the cut-off definition of Ki-67 index. This review summarizes most studies on the prognostic and predictive value of Ki-67, analyzes the reasons for the discrepancies among the studies cited, and presents the necessity and clinical significance of scientifically defining the cut-off of Ki-67 index, providing a theoretical basis for Ki-67 in clinical application.

Correlation between Body Mass Index, Gender, and Skeletal Muscle Mass Cut off Point in Bandung

Directory of Open Access Journals (Sweden)

Richi Hendrik Wattimena

2017-09-01

Full Text Available Objective: To determine the average skeletal muscle mass (SMM value in young adults as a reference population; to analyze the correlation of gender, and body mass index to the cut off point; and to determine skeletal muscle mass cut off points of population in Bandung, Indonesia. Methods: This was a cross-sectional study involving 199 participants, 122 females and 77 males. The sampling technique used was the multistage random sampling. The participants were those who lived in four major regions in Bandung, Indonesia: Sukajadi, Cicadas, Buah Batu, and Cibaduyut. Results: The average appendicular skeletal mass index (ASMI in females and males based on body mass index (BMI were identified. The average ASMI values for normal BMI in females was 5.982±0.462 kg/m2 while the average ASMI values normal BMI for males was 7.581±0.744 kg/m2 Conclusions: A correlation between BMI and ASMI that was considered statistically significant was found in females (0.7712; p<0.05 and a very significant correlation was seen in males (0.870; p<0.05. The cut off points were defined by the normal BMI, which were 5.059 for females and 6.093 for males.

Serum anti-PLA2R antibody as a diagnostic biomarker of idiopathic membranous nephropathy: The optimal cut-off value for Chinese patients.

Science.gov (United States)

Liu, Yipeng; Li, Xuan; Ma, Chaoqun; Wang, Ping; Liu, Ju; Su, Hong; Zhuo, Hao; Kong, Xianglei; Xu, Dayu; Xu, Dongmei

2018-01-01

The M-type phospholipase A2 receptor (PLA2R) is a specific target autoantigen identified in idiopathic membranous nephropathy (IMN). The autoantibody against PLA2R (anti-PLA2R) may be used to diagnose IMN. However, the appropriate diagnosis cut-off value for Chinese patients with IMN has not been established. In total, 119 patients who underwent renal biopsy (57 patients with IMN and 62 patients with non-IMN glomerulonephritis) and 22 healthy individuals were recruited for our observation study from Qianfoshan Hospital between September 2011 and March 2016. The serum concentration of anti-PLA2R was measured using a quantitative enzyme-linked immunosorbent assay (ELISA). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and receiver operating characteristic (ROC) curve of anti-PLA2R in diagnosing IMN were analysed based on the ELISA detection. The sensitivity, specificity, PPV, and NPV of anti-PLA2R in the diagnosis of IMN in the Chinese patients were 82.5, 75, 69.1, and 86.3% for the 2RU/ml cut-off value; 78.9, 91.7, 86.5, and 86.5% for the 2.6RU/ml cut-off value; 59.6, 95.2, 89.5, and 77.7% for the 14RU/ml cut-off value; 50.9, 96.4, 90.6, and 74.3% for the 20RU/ml cut-off value; and 47.4, 97.6, 93.1, and 73.2% for the 40RU/ml cut-off value, respectively. The area under the ROC curve was 0.879. The cut-off value of 2.6RU/ml is recommended for the use of anti-PLA2R for the diagnosis of IMN in Chinese patients based on the ELISA. Copyright © 2017. Published by Elsevier B.V.

The Portuguese version of the Outcome Questionnaire (OQ-45): Normative data, reliability, and clinical significance cut-offs scores.

Science.gov (United States)

Machado, Paulo P P; Fassnacht, Daniel B

2015-12-01

The Outcome Questionnaire (OQ-45) is one of the most extensively used standardized self-report instruments to monitor psychotherapy outcomes. The questionnaire is designed specifically for the assessment of change during psychotherapy treatments. Therefore, it is crucial to provide norms and clinical cut-off values for clinicians and researchers. The current study aims at providing study provides norms, reliability indices, and clinical cut-off values for the Portuguese version of the scale. Data from two large non-clinical samples (high school/university, N = 1,669; community, N = 879) and one clinical sample (n = 201) were used to investigate psychometric properties and derive normative data for all OQ-45 subscales and the total score. Significant and substantial differences were found for all subscales between the clinical and non-clinical sample. The Portuguese version also showed adequate reliabilities (internal consistency, test-retest), which were comparable to the original version. To assess individual clinical change, clinical cut-off values and reliable change indices were calculated allowing clinicians and researchers to monitor and evaluate clients' individual change. The Portuguese version of the OQ-45 is a reliable instrument with comparable Portuguese norms and cut-off scores to those from the original version. This allows clinicians and researchers to use this instrument for evaluating change and outcome in psychotherapy. This study provides norms for non-clinical and clinical Portuguese samples and investigates the reliability (internal consistency and test-retest) of the OQ-45. Cut-off values and reliable change index are provided allowing clinicians to evaluate clinical change and clients' response to treatment, monitoring the quality of mental health care services. These can be used, in routine clinical practice, as benchmarks for treatment progress and to empirically base clinical decisions such as continuation of treatment or considering

The continuous cut-off method and the relativistic scattering of spin-1/2 particles

International Nuclear Information System (INIS)

Dolinszky, T.

1979-07-01

A high energy formula, obtained in the framework of the continuous cut-off approach, is shown to improve the correctness of the standard phase shift expression for Dirac scattering by two orders of magnitude in energy. (author)

Detection of relevant colonic neoplasms with PET/CT: promising accuracy with minimal CT dose and a standardised PET cut-off

Energy Technology Data Exchange (ETDEWEB)

Luboldt, Wolfgang [Multiorgan Screening Foundation, Frankfurt (Germany); University Hospital Frankfurt, Department of Radiology, Frankfurt am Main (Germany); University Hospital Dresden, Clinic and Policlinic of Nuclear Medicine, Dresden (Germany); Volker, Teresa; Zoephel, Klaus; Kotzerke, Joerg [University Hospital Dresden, Clinic and Policlinic of Nuclear Medicine, Dresden (Germany); Wiedemann, Baerbel [University Hospital Dresden, Institute of Medical Informatics and Biometrics, Dresden (Germany); Wehrmann, Ursula [University Hospital Dresden, Clinic and Policlinic of Surgery, Dresden (Germany); Koch, Arne; Abolmaali, Nasreddin [University Hospital Dresden, Oncoray, Dresden (Germany); Toussaint, Todd; Luboldt, Hans-Joachim [Multiorgan Screening Foundation, Frankfurt (Germany); Middendorp, Markus; Gruenwald, Frank [University Hospital Frankfurt, Department of Nuclear Medicine, Frankfurt (Germany); Aust, Daniela [University Hospital Dresden, Department of Pathology, Dresden (Germany); Vogl, Thomas J. [University Hospital Frankfurt, Department of Radiology, Frankfurt am Main (Germany)

2010-09-15

To determine the performance of FDG-PET/CT in the detection of relevant colorectal neoplasms (adenomas {>=}10 mm, with high-grade dysplasia, cancer) in relation to CT dose and contrast administration and to find a PET cut-off. 84 patients, who underwent PET/CT and colonoscopy (n=79)/sigmoidoscopy (n=5) for (79 x 6+5 x 2)=484 colonic segments, were included in a retrospective study. The accuracy of low-dose PET/CT in detecting mass-positive segments was evaluated by ROC analysis by two blinded independent reviewers relative to contrast-enhanced PET/CT. On a per-lesion basis characteristic PET values were tested as cut-offs. Low-dose PET/CT and contrast-enhanced PET/CT provide similar accuracies (area under the curve for the average ROC ratings 0.925 vs. 0.929, respectively). PET demonstrated all carcinomas (n=23) and 83% (30/36) of relevant adenomas. In all carcinomas and adenomas with high-grade dysplasia (n=10) the SUV{sub max} was {>=}5. This cut-off resulted in a better per-segment sensitivity and negative predictive value (NPV) than the average PET/CT reviews (sensitivity: 89% vs. 82%; NPV: 99% vs. 98%). All other tested cut-offs were inferior to the SUV{sub max}. FDG-PET/CT provides promising accuracy for colorectal mass detection. Low dose and lack of iodine contrast in the CT component do not impact the accuracy. The PET cut-off SUV{sub max}{>=} 5 improves the accuracy. (orig.)

Detection of relevant colonic neoplasms with PET/CT: promising accuracy with minimal CT dose and a standardised PET cut-off

International Nuclear Information System (INIS)

Luboldt, Wolfgang; Volker, Teresa; Zoephel, Klaus; Kotzerke, Joerg; Wiedemann, Baerbel; Wehrmann, Ursula; Koch, Arne; Abolmaali, Nasreddin; Toussaint, Todd; Luboldt, Hans-Joachim; Middendorp, Markus; Gruenwald, Frank; Aust, Daniela; Vogl, Thomas J.

2010-01-01

To determine the performance of FDG-PET/CT in the detection of relevant colorectal neoplasms (adenomas ≥10 mm, with high-grade dysplasia, cancer) in relation to CT dose and contrast administration and to find a PET cut-off. 84 patients, who underwent PET/CT and colonoscopy (n=79)/sigmoidoscopy (n=5) for (79 x 6+5 x 2)=484 colonic segments, were included in a retrospective study. The accuracy of low-dose PET/CT in detecting mass-positive segments was evaluated by ROC analysis by two blinded independent reviewers relative to contrast-enhanced PET/CT. On a per-lesion basis characteristic PET values were tested as cut-offs. Low-dose PET/CT and contrast-enhanced PET/CT provide similar accuracies (area under the curve for the average ROC ratings 0.925 vs. 0.929, respectively). PET demonstrated all carcinomas (n=23) and 83% (30/36) of relevant adenomas. In all carcinomas and adenomas with high-grade dysplasia (n=10) the SUV max was ≥5. This cut-off resulted in a better per-segment sensitivity and negative predictive value (NPV) than the average PET/CT reviews (sensitivity: 89% vs. 82%; NPV: 99% vs. 98%). All other tested cut-offs were inferior to the SUV max . FDG-PET/CT provides promising accuracy for colorectal mass detection. Low dose and lack of iodine contrast in the CT component do not impact the accuracy. The PET cut-off SUV max ≥ 5 improves the accuracy. (orig.)

A Study on the Manufacturing Properties of Crack Self-Healing Capsules Using Cement Powder for Addition to Cement Composites

OpenAIRE

Choi, Yun-Wang; Oh, Sung-Rok; Choi, Byung-Keol

2017-01-01

We fabricated crack self-healing capsules using cement powder for mixing into cement composites and evaluated the properties of the capsule manufacturing process in this study. The manufacture of the self-healing capsules is divided into core production processing of granulating cement in powder form and a coating process for creating a wall on the surfaces of the granulated cement particles. The produced capsules contain unhardened cement and can be mixed directly with the cement composite m...

Definition of new cut-offs of BMI and waist circumference based on body composition and insulin resistance: differences between children, adolescents and adults.

Science.gov (United States)

Hübers, M; Pourhassan, M; Braun, W; Geisler, C; Müller, M J

2017-09-01

This study aims to determine associations between anthropometric traits, regional fat depots and insulin resistance in children, adolescents and adults to define new cut-offs of body mass index (BMI) or waist circumference (WC). Cross-sectional data were assessed in 433 children, adolescents and adults (aged: 6-60 years, BMI: 23.6 [21.0-27.7] kg m -2 ). Total adipose tissue (TAT), regional subcutaneous adipose tissue (SAT total , SAT trunk ) and visceral adipose tissue (VAT) were determined by whole-body magnetic resonance imaging, fat mass by air-displacement plethysmography. Insulin resistance was evaluated by homeostasis model assessment of insulin resistance (HOMA-IR). Bivariate as well as partial correlations and regression analyses were used. Cut-off values of BMI and WC related to regional fat depots and HOMA-IR were analysed by receiver operating characteristics curve. In adults, TAT, SAT total and SAT trunk increased linearly with increasing BMI and WC, whereas they followed a cubic function in children and adolescents with a steep increase at BMI and WC ≥1 standard deviation score and VAT at WC ≥2 standard deviation score. Sex differences were apparent in adults with women having higher masses of TAT and SAT and men having higher VAT. Using established BMI or WC cut-offs, correspondent masses of TAT, SAT total , SAT trunk and VAT increased from childhood to adulthood. In all age groups, there were positive associations between BMI, WC, SAT trunk , VAT and HOMA-IR. When compared with normative cut-offs of BMI or WC, HOMA-IR-derived cut-offs of regional fat depots were lower in all age groups. Associations between BMI, WC and regional fat depots varied between children, adolescents, young and older adults. When compared with BMI-derived and WC-derived values, an insulin resistance-derived cut-off corresponded to lower masses of regional fat depots. Thus, established BMI and WC cut-offs are not appropriate to assess metabolic disturbances associated

Lifetime of Bentonites study: hydrothermal stability of saponites; Estudio de longevidad en bentonitas: estabilidad hidrotermal de saponitas

Energy Technology Data Exchange (ETDEWEB)

Leguey, S; Cuevas, J; Garralon, A [Universidad Autonoma de Madrid, Facultad de Ciencias, Departamento de Quimica Agricola, Geologia y Geoquimica, Madrid (Spain)

1996-10-01

The report studies the lifetime of bentonite and the hydrothermal stability of saponites. The testing comprised determination of physical and chemical properties of clays, the stability of the mineral porosity, lifetime and the wall of clay.

Practical use of visual medial temporal lobe atrophy cut-off scores in Alzheimer's disease: Validation in a large memory clinic population

International Nuclear Information System (INIS)

Claus, Jules J.; Holl, Dana C.; Roorda, Jelmen J.; Staekenborg, Salka S.; Schuur, Jacqueline; Koster, Pieter; Tielkes, Caroline E.M.; Scheltens, Philip

2017-01-01

To provide age-specific medial temporal lobe atrophy (MTA) cut-off scores for routine clinical practice as marker for Alzheimer's disease (AD). Patients with AD (n = 832, mean age 81.8 years) were compared with patients with subjective cognitive impairment (n = 333, mean age 71.8 years) in a large single-centre memory clinic. Mean of right and left MTA scores was determined with visual rating (Scheltens scale) using CT (0, no atrophy to 4, severe atrophy). Relationships between age and MTA scores were analysed with regression analysis. For various MTA cut-off scores, decade-specific sensitivity and specificity and area under the curve (AUC) values, computed with receiver operator characteristic curves, were determined. MTA strongly increased with age in both groups to a similar degree. Optimal MTA cut-off values for the age ranges <65, 65-74, 75-84 and ≥85 were: ≥1.0, ≥1.5, ≥ 2.0 and ≥2.0. Corresponding values of sensitivity and specificity were 83.3% and 86.4%; 73.7% and 84.6%; 73.7% and 76.2%; and 84.0% and 62.5%. From this large unique memory clinic cohort we suggest decade-specific MTA cut-off scores for clinical use. After age 85 years, however, the practical usefulness of the MTA cut-off is limited. (orig.)

Selfinjection of highly compacted bentonite into rock joints

International Nuclear Information System (INIS)

Pusch, R.

1978-02-01

When radioactive waste is disposed in bore holes in rocks there will be some space between rock and canister. Other investigations have suggested that the space could be filled with highly compacted bentonite. In this report it is discussed if open joints formed or widened in the surrounding rock after the deposition will be sealed by self-injecting bentonite. Bentonite in contact with water will swell. The flow pattern and properties of the swelling bentonite, the permeability of the extruded bentonite and the viscosity of the extruded bentonite have been investigated. The following statements are done. In the narrow joints that can possibly be opened by various processes, the rate of bentonite extrusion will be very slow except for the first few centimeter move, which may take place in a few mounths. The swelling pressure of the extruded bentonite will decrease rapidly with the distance from the deposition hole. The loss of bentonite extruded through the narrow joints will be negligible. In the outer part of the bentonite zone there will be a successive transition to a very soft, dilute bentonite suspension. It will consist of fairly large particle aggregates which will be stuck where the joint width decreases

Revisiting the Phadia/EliA cut-off values for anticardiolipin and anti-β2-glycoprotein I antibodies: a systematic evaluation according to the guidelines.

Science.gov (United States)

Bor, M V; Jacobsen, I-L Søtang; Gram, J B; Sidelmann, J J

2018-01-01

Background Phadia/EliA fluorescence enzyme immunoassays are widely used automated assays for anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies. To date, cut-off values for these assays have not been evaluated systematically and the evidence behind manufacturer's recommended cut-off values is not clear. Objective To determine Phadia/EliA cut-off values for antiphospholipid antibodies (aPL) according to the procedures suggested by guidelines. Methods A total of 266 blood donors (135 females and 131 males) were included. The pre-handling and analysis of the samples were performed according to the International Society on Thrombosis and Hemostasis (ISTH) guideline for solid phase aPL assays. Cut-off values and corresponding 90% confidence intervals (CI) for each antibody were established and outliers were handled according to the Clinical and Laboratory Standards Institute (CLSI) guideline for reference intervals. Samples from 377 consecutive patients, referred to our thrombophilia center with evidence of thrombosis or pregnancy morbidity were included for aPL testing. Results The in-house 99th (97.5th) percentile cut-off values were 11 (8.7), 12 (6.9) 8.5 (5.0) AU/mL for aβ2GPI IgG, IgM and IgA, and 21 (13) GPL-U/mL and 41 (25) MPL-U/mL for aCL IgG and IgM, respectively. The prevalence of positive results (%) defined by these cut-off values in patients with evidence of thrombosis or pregnancy morbidity was 9.5 (12.2), 1.6 (2.9), and 7.0 (9.9), and 0.8 (3.8) for aβ2GPI IgG, IgM, and aCL IgG and IgM respectively. The use of in-house 99th percentile cut-off values compared to the manufacturer suggested cut-off values resulted in 1 and 39 fewer samples for aβ2GPI and aCL to be classified as positive for aPL, respectively. Conclusions We present Phadia/EliA cut-off values with 90% CI for aPL determined systematically according to the ISTH and CLSI guidelines. These values are different from values previously determined, suggesting variation of a

Corrosion of carbon steel in contact with bentonite

International Nuclear Information System (INIS)

Dobrev, D.; Vokal, A.; Bruha, P.

2010-01-01

Document available in extended abstract form only. Carbon steel canisters were chosen in a number of disposal concepts as reference material for disposal canisters. The corrosion rates of carbon steels in water solution both in aerobic and anaerobic conditions are well known, but only scarce data are available for corrosion behaviour of carbon steels in contact with bentonite. A special apparatus, which enables to measure corrosion rate of carbon steels under conditions simulating conditions in a repository, namely in contact with bentonite under high pressure and elevated temperatures was therefore prepared to study: - Corrosion rate of carbon steels in direct contact with bentonite in comparison with corrosion rate of carbon steels in synthetic bentonite pore water. - Influence of corrosion products on bentonite. The apparatus is composed of corrosion chamber containing a carbon steel disc in direct contact with compacted bentonite. Synthetic granitic water is above compacted bentonite under high pressure (50 - 100 bar) to simulate hydrostatic pressure in a repository. The experiments can be carried out under various temperatures. Bentonites used for experiments were Na-type of bentonite Volclay KWK 80 - 20 and Ca-Mg Czech bentonite from deposit Rokle. Before adding water into corrosion system the corrosion chamber was purged by nitrogen gas. The saturation of bentonite and corrosion rate were monitored by measuring consumption of water, pressure increase caused by swelling pressure of bentonite and by generation of hydrogen. Corrosion rate was also determined after corrosion experiments from weight loss of samples. The results of experiments show that the corrosion behaviour of carbon steels in contact with bentonite is very different from corrosion of carbon steels in water simulating bentonite pore water solution. The corrosion rates of carbon steel in contact with bentonite reached after 30 days of corrosion the values approaching 40 mm/yr contrary to values

Assessment Criteria of Bentonite Binding Properties

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S. Żymankowska-Kumon

2012-09-01

Full Text Available The criteria, with which one should be guided at the assessment of the binding properties of bentonites used for moulding sands, areproposed in the paper. Apart from the standard parameter which is the active bentonite content, the unrestrained growth indicator should be taken into account since it seems to be more adequate in the estimation of the sand compression strength. The investigations performed for three kinds of bentonites, applied in the Polish foundry plants, subjected to a high temperature influences indicate, that the pathway of changes of the unrestrained growth indicator is very similar to the pathway of changes of the sand compression strength. Instead, the character of changes of the montmorillonite content in the sand in dependence of the temperature is quite different. The sand exhibits the significant active bentonite content, and the sand compression strength decreases rapidly. The montmorillonite content in bentonite samples was determined by the modern copper complex method of triethylenetetraamine (Cu(II-TET. Tests were performed for bentonites and for sands with those bentonites subjected to high temperatures influences in a range: 100-700ºC.

Preliminary investigation on welding and cutting methods for first wall support leg in ITER blanket module

International Nuclear Information System (INIS)

Mohri, Kensuke; Suzuki, Satoshi; Enoeda, Mikio; Kakudate, Satoshi; Shibanuma, Kiyoshi; Akiba, Masato

2006-08-01

Concept of a module type of blanket has been applied to ITER shield blanket, of which size is typically 1mW x 1mH x 0.4mB with the weight of 4 ton, in order to enhance its maintainability and fabricability. Each shield blanket module consists of a shield block and four first walls which are separable from the shield block for the purpose of reduction of an electro-magnetic force in disruption events, radio-active waste reduction in the maintenance work and cost reduction in fabrication process. A first wall support leg, a part of the first wall component located between the first wall and the shield block, is required not only to be connected metallurgically to the shield block in order to withstand the electro-magnetic force and coolant pressure, but also to be able to replace the first wall more than 2 times in the hot cell during the life time of the reactor. Therefore, the consistent structure where remote handling equipment can be access to the joint and carry out the welding/cutting works perfectly to replace the first wall in the hot cell is required in the shield blanket design. This study shows an investigation of the blanket module no.10 design with a new type of the first wall support leg structure based on Disc-Cutter technology, which had been developed for the main pipe cutting in the maintenance phase and was selected out of a number of candidate methods, taking its large advantages into account, such as 1) a post-treatment can be eliminated in the hot cell because of no making material chips and of no need of lubricant, 2) the cut surface can be rewelded without any machining. And also, a design for the small type of Disc-Cutter applied to the new blanket module no.10 has been investigated. In conclusion, not only the good performance of Disc-Cutter technology applied to the updated blanket module, but also consistent structure of the simplified shield blanket module including the first wall support leg in order to satisfy the requirements in the

Modeling of Coupled Thermo-Hydro-Mechanical-Chemical Processes for Bentonite in a Clay-rock Repository for Heat-generating Nuclear Waste

Science.gov (United States)

Xu, H.; Rutqvist, J.; Zheng, L.; Birkholzer, J. T.

2016-12-01

Engineered Barrier Systems (EBS) that include a bentonite-based buffer are designed to isolate the high-level radioactive waste emplaced in tunnels in deep geological formations. The heat emanated from the waste can drive the moisture flow transport and induce strongly coupled Thermal (T), Hydrological (H), Mechanical (M) and Chemical (C) processes within the bentonite buffer and may also impact the evolution of the excavation disturbed zone and the sealing between the buffer and walls of an emplacement tunnel The flow and contaminant transport potential along the disturbed zone can be minimized by backfilling the tunnels with bentonite, if it provides enough swelling stress when hydrated by the host rock. The swelling capability of clay minerals within the bentonite is important for sealing gaps between bentonite block, and between the EBS and the surrounding host rock. However, a high temperature could result in chemical alteration of bentonite-based buffer and backfill materials through illitization, which may compromise the function of these EBS components by reducing their plasticity and capability to swell under wetting. Therefore, an adequate THMC coupling scheme is required to understand and to predict the changes of bentonite for identifying whether EBS bentonite can sustain higher temperatures. More comprehensive links between chemistry and mechanics, taking advantage of the framework provided by a dual-structure model, named Barcelona Expansive Model (BExM), was implemented in TOUGHREACT-FLAC3D and is used to simulate the response of EBS bentonite in in clay formation for a generic case. The current work is to evaluate the chemical changes in EBS bentonite and the effects on the bentonite swelling stress under high temperature. This work sheds light on the interaction between THMC processes, evaluates the potential deterioration of EBS bentonite and supports the decision making in the design of a nuclear waste repository in light of the maximum allowance

Prediction for swelling characteristics of compacted bentonite

International Nuclear Information System (INIS)

Komine, H.; Ogata, N.

1996-01-01

Compacted bentonites are attracting greater attention as back-filling (buffer) materials for high-level nuclear waste repositories. For this purpose, it is very important to quantitatively evaluate the swelling characteristics of compacted bentonite. New equations for evaluating the relationship between the swelling deformation of compacted bentonite and the distance between two montmorillonite layers are derived. New equations for evaluating the ion concentration of pore water and the specific surface of bentonite, which significantly influence the swelling characteristics of compacted bentonite, are proposed. Furthermore, a prediction method for the swelling characteristics of compacted bentonite is presented by combining the new equations with the well-known theoretical equations of repulsive and attractive forces between two montmorillonite layers. The applicability of this method was investigated by comparing the predicted results with laboratory test results on the swelling deformation and swelling pressure of compacted bentonites. (author) 31 refs., 8 tabs., 12 figs

The assessment of anorexia in patients with cancer: cut-off values for the FAACT-A/CS and the VAS for appetite.

Science.gov (United States)

Blauwhoff-Buskermolen, S; Ruijgrok, C; Ostelo, R W; de Vet, H C W; Verheul, H M W; de van der Schueren, M A E; Langius, J A E

2016-02-01

Anorexia is a frequently observed symptom in patients with cancer and is associated with limited food intake and decreased quality of life. Diagnostic instruments such as the Anorexia/Cachexia Subscale (A/CS) of the Functional Assessment of Anorexia/Cachexia Therapy (FAACT) questionnaire and the visual analog scale (VAS) for appetite have been recommended in the assessment of anorexia, but validated cut-off values are lacking. This study aimed to obtain cut-off values of these instruments for the assessment of anorexia in patients with cancer. The FAACT-A/CS and the VAS for appetite were administered to patients with cancer before start of chemotherapy. As reference standard for anorexia, two external criteria were used: (1) a cut-off value of ≥2 on the anorexia symptom scale of the EORTC QLQ C-30 and (2) the question "Do you experience a decreased appetite?" (yes/no). ROC curves were used to examine the optimal cut-off values for the FAACT-A/CS and VAS. A total of 273 patients (58 % male; 64.0 ± 10.6 years) were included. The median score on the FAACT-A/CS was 38 (IQR 32-42) points and 77 (IQR 47-93) points on the VAS. Considering both external criteria, the optimal cut-off value for the FAACT-A/CS was ≤37 (sensitivity (se) 80 %, specificity (sp) 81 %, positive predictive value (PV(+)) 79 %, negative predictive value (PV(-)) 82 %) and for the VAS was ≤70 (se 76 %, sp 83 %, PV(+) 80 %, PV(-) 79 %). For the assessment of anorexia in patients with cancer, our study suggests cut-off values of ≤37 for the FAACT-A/CS and ≤70 for the VAS. Future studies should confirm our findings in other patient samples.

Cut-Off Levels of Anti-Mullerian Hormone for The Prediction of Ovarian Response, In Vitro Fertilization Outcome and Ovarian Hyperstimulation Syndrome

Directory of Open Access Journals (Sweden)

Ali Salmassi

2015-07-01

Full Text Available Background: Evaluation of anti-mullerian hormone (AMH cut-off levels in assisted reproductive technology (ART as predictive factor for individualization of stimulation protocols and to avoid ovarian hyperstimulation syndrome (OHSS. Materials and Methods: In a retrospective study, 177 infertile patients were assessed for AMH in serum and follicular fluid (FF on the day of follicular puncture (FP, between 2012 and 2013 in Kiel, Germany. AMH levels and pregnancy rates were compared between low, moderate and high responders and cut-off levels of low and high responders. AMH cut-off levels in pathological cases were evaluated in analysis 1 (OHSS and in analysis 2 [polycystic ovarian syndrome, (PCOS] and compared in analysis 3 to normal endocrinological parameters. Results: AMH levels in FF were higher than in serum (P<0.001. AMH levels in serum and FF increased from low through moderate to high responders (P<0.001. Pregnancy rates were 14.7, 23.3 and 44.9% (P=0.009, respectively. AMH cut-off level for poor responders was 0.61 ng/ml in serum with a pregnancy rate of 13.8 and 37.1% for below and above of this level, respectively. For FF, it was 1.43 ng/ml. AMH levels in analysis 1 and 2 were significantly higher than in analysis 3 (P=0.001. AMH cut-off level for OHSS was 1.5 ng/ml in serum with OHSS rates of 80.8 and 19.2 % for above and below of the level, respectively. For FF, it was 2.7 ng/ml. PCOS patients had an AMH cut-off level of 3.9 ng/ml in serum and 6.8 ng/ml in FF, resulting in a PCOS rate of 100% above this level. Conclusion: AMH levels can help to assess ovarian response potential and guide ovarian stimulation while avoiding OHSS.

Quality assurance of the bentonite material

International Nuclear Information System (INIS)

Ahonen, L.; Korkeakoski, P.; Tiljander, M.; Kivikoski, H.; Laaksonen, R.

2008-05-01

This report describes a quality assurance chain for the bentonite material acquisition for a nuclear waste disposal repository. Chemical, mineralogical and geotechnical methods, which may be applied in quality control of bentonite are shortly reviewed. As a case study, many of the presented control studies were performed for six different bentonite samples. Chemical analysis is a very reliable research method to control material homogeneity, because the accuracy and repeatability of the study method is extremely good. Accurate mineralogical study of bentonite is a complicated task. X-ray diffractometry is the best method to identify smectite minerals, but quantitative analysis of smectite content remains uncertain. To obtain a better quantitative analysis, development of techniques based on automatic image analysis of SEM images is proposed. General characteristics of bentonite can be obtained by rapid indicator tests, which can be done on the place of reception. These tests are methylene blue test giving information on the cation exchange capacity, swelling index and determination of water absorption. Different methods were used in the determination of cation exchange capacity (CEC) of bentonite. The results indicated differences both between methodologies and between replicate determinations for the same material and method. Additional work should be done to improve the reliability and reproducibility of the methodology. Bentonite contains water in different modes. Thus, different determination methods are used in bentonite studies and they give somewhat dissimilar results. Clay research use frequently the so-called consistency tests (liquid limit, plastic limit and plasticity index). This study method does, however, not seem to be very practical in quality control of bentonite. Therefore, only the determination of liquid limit with fall-cone method is recommended for quality control. (orig.)

Review of the properties and uses of bentonite as a buffer and backfill material

International Nuclear Information System (INIS)

Savage, D.; Lind, A.; Arthur, R.C.

1999-05-01

similar studies elsewhere and is therefore contentious and open to debate. There seems to be a general lack of integration of analogue studies with modelling and experimental work in terms of a model of the evolution of the chemistry of bentonite pore fluids with time (i.e. analogue evidence demonstrates the importance of mineral dissolution and precipitation, but this is not incorporated into the chemical modelling approach). Some rationalisation of approaches is required for a credible model of bentonite pore water evolution to be created. There is little apparent use of modelled bentonite pore water chemistry for the calculation of radionuclide solubility, sorption and speciation in PA (c.f. approaches used by Nagra, JNC, TVO). Although recent work in part redresses this imbalance, SKB is alone amongst disposal agencies in this approach. There is little published work by SKB on the interaction of bentonite with cement. There is now a growing literature elsewhere on this subject which does not seem to be reflected in studies carried out by SKB. Collaboration with other waste disposal authorities interested in this topic is recommended. It may be necessary to incorporate chemical processes into the current SKB conceptual model of gas transport in buffer and backfill materials. Dissolved or gaseous H 2 is generated by Fe corrosion under anaerobic conditions, and this gas may be reactive with several minerals in bentonite, including smectite. Although field tests carried out by SKB suggest that the emplacement of compacted bentonite will not be a problem from the perspective of buffer performance, borehole, shaft and vault sealing, there are apparent problems for block manufacture. The introduction of oil as a lubricant in block manufacture, for example may pose problems for long-term behaviour of the near-field due to the presence of these organic materials. Better manufacturing methods are therefore required

Review of the properties and uses of bentonite as a buffer and backfill material

Energy Technology Data Exchange (ETDEWEB)

Savage, D.; Lind, A. [QuantiSci Ltd., Melton Mowbray (United Kingdom); Arthur, R.C. [QuantiSci lnc., Denver, CO (United States)

1999-05-01

similar studies elsewhere and is therefore contentious and open to debate. There seems to be a general lack of integration of analogue studies with modelling and experimental work in terms of a model of the evolution of the chemistry of bentonite pore fluids with time (i.e. analogue evidence demonstrates the importance of mineral dissolution and precipitation, but this is not incorporated into the chemical modelling approach). Some rationalisation of approaches is required for a credible model of bentonite pore water evolution to be created. There is little apparent use of modelled bentonite pore water chemistry for the calculation of radionuclide solubility, sorption and speciation in PA (c.f. approaches used by Nagra, JNC, TVO). Although recent work in part redresses this imbalance, SKB is alone amongst disposal agencies in this approach. There is little published work by SKB on the interaction of bentonite with cement. There is now a growing literature elsewhere on this subject which does not seem to be reflected in studies carried out by SKB. Collaboration with other waste disposal authorities interested in this topic is recommended. It may be necessary to incorporate chemical processes into the current SKB conceptual model of gas transport in buffer and backfill materials. Dissolved or gaseous H{sub 2} is generated by Fe corrosion under anaerobic conditions, and this gas may be reactive with several minerals in bentonite, including smectite. Although field tests carried out by SKB suggest that the emplacement of compacted bentonite will not be a problem from the perspective of buffer performance, borehole, shaft and vault sealing, there are apparent problems for block manufacture. The introduction of oil as a lubricant in block manufacture, for example may pose problems for long-term behaviour of the near-field due to the presence of these organic materials. Better manufacturing methods are therefore required 112 refs, 4 figs, 4 tabs

Exploring optimum cut-off scores to screen for probable posttraumatic stress disorder within a sample of UK treatment-seeking veterans

Science.gov (United States)

Murphy, Dominic; Ross, Jana; Ashwick, Rachel; Armour, Cherie; Busuttil, Walter

2017-01-01

ABSTRACT Background: Previous research exploring the psychometric properties of the scores of measures of posttraumatic stress disorder (PTSD) suggests there is variation in their functioning depending on the target population. To date, there has been little study of these properties within UK veteran populations. Objective: This study aimed to determine optimally efficient cut-off values for the Impact of Event Scale-Revised (IES-R) and the PTSD Checklist for DSM-5 (PCL-5) that can be used to assess for differential diagnosis of presumptive PTSD. Methods: Data from a sample of 242 UK veterans assessed for mental health difficulties were analysed. The criterion-related validity of the PCL-5 and IES-R were evaluated against the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5). Kappa statistics were used to assess the level of agreement between the DSM-IV and DSM-5 classification systems. Results: The optimal cut-off scores observed within this sample were 34 or above on the PCL-5 and 46 or above on the IES-R. The PCL-5 cut-off is similar to the previously reported values, but the IES-R cut-off identified in this study is higher than has previously been recommended. Overall, a moderate level of agreement was found between participants screened positive using the DSM-IV and DSM-5 classification systems of PTSD. Conclusions: Our findings suggest that the PCL-5 and IES-R can be used as brief measures within veteran populations presenting at secondary care to assess for PTSD. The use of a higher cut-off for the IES-R may be helpful for differentiating between veterans who present with PTSD and those who may have some sy`mptoms of PTSD but are sub-threshold for meeting a diagnosis. Further, the use of more accurate optimal cut-offs may aid clinicians to better monitor changes in PTSD symptoms during and after treatment. PMID:29435200

Exploring optimum cut-off scores to screen for probable posttraumatic stress disorder within a sample of UK treatment-seeking veterans.

Science.gov (United States)

Murphy, Dominic; Ross, Jana; Ashwick, Rachel; Armour, Cherie; Busuttil, Walter

2017-01-01

Background : Previous research exploring the psychometric properties of the scores of measures of posttraumatic stress disorder (PTSD) suggests there is variation in their functioning depending on the target population. To date, there has been little study of these properties within UK veteran populations. Objective : This study aimed to determine optimally efficient cut-off values for the Impact of Event Scale-Revised (IES-R) and the PTSD Checklist for DSM-5 (PCL-5) that can be used to assess for differential diagnosis of presumptive PTSD. Methods : Data from a sample of 242 UK veterans assessed for mental health difficulties were analysed. The criterion-related validity of the PCL-5 and IES-R were evaluated against the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5). Kappa statistics were used to assess the level of agreement between the DSM-IV and DSM-5 classification systems. Results : The optimal cut-off scores observed within this sample were 34 or above on the PCL-5 and 46 or above on the IES-R. The PCL-5 cut-off is similar to the previously reported values, but the IES-R cut-off identified in this study is higher than has previously been recommended. Overall, a moderate level of agreement was found between participants screened positive using the DSM-IV and DSM-5 classification systems of PTSD. Conclusions : Our findings suggest that the PCL-5 and IES-R can be used as brief measures within veteran populations presenting at secondary care to assess for PTSD. The use of a higher cut-off for the IES-R may be helpful for differentiating between veterans who present with PTSD and those who may have some sy`mptoms of PTSD but are sub-threshold for meeting a diagnosis. Further, the use of more accurate optimal cut-offs may aid clinicians to better monitor changes in PTSD symptoms during and after treatment.

Sinus cut-off sign: A helpful sign in the CT diagnosis of diaphragmatic rupture associated with pleural effusion

International Nuclear Information System (INIS)

Kaya, Seyda Ors; Karabulut, Nevzat; Yuncu, Gokhan; Sevinc, Serpil; Kiroglu, Yilmaz

2006-01-01

The objective of our study was to describe the 'sinus cut-off' sign at CT in the diagnosis of diaphragmatic rupture in patients with blunt abdominal trauma complicated with pleural effusion, and evaluate its utility in an experimental model. Between January 2004 and March 2005, we observed an unusual interruption of costophrenic sinus at CT in three patients with blunt abdominal trauma accompanied with pleural effusion. This observation prompted us to evaluate the utility of this sign in an experimental model. Laparotomically, we created 2 cm diapragmatic lacerations at each hemidiaphragm in two rabbits and pushed up the abdominal viscera with omentum through the defect. To simulate hemothorax, we also injected 5-10 mL of diluted contrast material into the pleural space. Using a dual-slice helical CT scanner, limited thoracoabdominal CT examination was performed before and after injection of intrapleural contrast material. The images were analyzed for the presence of CT signs for diaphragmatic injury. The left posterior costophrenic sulcus was interrupted in all of the three patients with left pleural effusion. While it was associated with other findings of diaphragmatic injury, the 'sinus cut-off sign' was the sole finding in one patient. The sinus cut-off sign was observed on the CT scans of 100% of the rabbits with a left and right sided diaphragmatic rupture. The 'sinus cut-off sign' is useful and can increase the CT detection of acute diaphragmatic injury associated with pleural effusion

Rheological Behavior of Bentonite-Polyester Dispersions

Science.gov (United States)

Abu-Jdayil, Basim; Al-Omari, Salah Addin

2013-07-01

The rheological behavior of a bentonite clay dispersed in unsaturated polyester was investigated. The effects of the solid content and particle size on the steady and transient rheological properties of the dispersions were studied. In addition, two types of bentonite with different Na+/Ca+2 ratio were used in this study. The Herschel-Bulkley and the Weltman models were used to describe the apparent viscosity of the bentonite-polyester composite in relation to the shear rate and shearing time. The bentonite-polyester dispersions were found to exhibit both Newtonian and non-Newtonian behavior. The transition from a Newtonian to a Bingham plastic and then to a shear-thinning material with a yield stress was found to depend on the solid concentration, the particle size, and the type of bentonite. At a low solid content, the apparent viscosity of the bentonite dispersion increased linearly with solid concentration. But a dramatic increase in the apparent viscosity beyond a solid content of 20 wt.% was observed. On the other hand, a thixotropic behavior was detected in bentonite-polyester dispersions with a high solid content and a low particle size. However, this behavior was more pronounced in dispersions with a high Na+/Ca+2 ratio.

Determinants of self-reported smoking and misclassification during pregnancy, and analysis of optimal cut-off points for urinary cotinine: a cross-sectional study.

Science.gov (United States)

Aurrekoetxea, Juan J; Murcia, Mario; Rebagliato, Marisa; López, María José; Castilla, Ane Miren; Santa-Marina, Loreto; Guxens, Mónica; Fernández-Somoano, Ana; Espada, Mercedes; Lertxundi, Aitana; Tardón, Adonina; Ballester, Ferran

2013-01-24

To estimate the prevalence and factors associated with smoking and misclassification in pregnant women from INMA (INfancia y Medio Ambiente, Environment and Childhood) project, Spain, and to assess the optimal cut-offs for urinary cotinine (UC) that best distinguish daily and occasional smokers with varying levels of second-hand smoke (SHS) exposure. We used logistic regression models to study the relationship between sociodemographic variables and self-reported smoking and misclassification (self-reported non-smokers with UC >50 ng/ml). Receiver operating characteristic (ROC) curves were used to calculate the optimal cut-off point for discriminating smokers. The cut-offs were also calculated after stratification among non-smokers by the number of sources of SHS exposure. The cut-off points used to discriminate smoking status were the level of UC given by Youden's index and for 50 and 100 ng/ml for daily smokers, or 25 and 50 ng/ml for occasional smokers. At the third trimester of pregnancy, 2263 pregnant women of the INMA Project were interviewed between 2004 and 2008 and a urine sample was collected. Prevalence of self-reported smokers at the third trimester of pregnancy was 18.5%, and another 3.9% misreported their smoking status. Variables associated with self-reported smoking and misreporting were similar, including born in Europe, educational level and exposure to SHS. The optimal cut-off was 82 ng/ml (95% CI 42 to 133), sensitivity 95.2% and specificity 96.6%. The area under the ROC curve was 0.986 (95% CI 0.982 to 0.990). The cut-offs varied according to the SHS exposure level being 42 (95% CI 27 to 57), 82 (95% CI 46 to 136) and 106 ng/ml (95% CI 58 to 227) for not being SHS exposed, exposed to one, and to two or more sources of SHS, respectively. The optimal cut-off for discriminating occasional smokers from non-smokers was 27 ng/ml (95% CI 11 to 43). Prevalence of smoking during pregnancy in Spain remains high. UC is a reliable biomarker for classifying

Determinants of self-reported smoking and misclassification during pregnancy, and analysis of optimal cut-off points for urinary cotinine: a cross-sectional study

Science.gov (United States)

Aurrekoetxea, Juan J; Murcia, Mario; Rebagliato, Marisa; López, María José; Castilla, Ane Miren; Santa-Marina, Loreto; Guxens, Mónica; Fernández-Somoano, Ana; Espada, Mercedes; Lertxundi, Aitana; Tardón, Adonina; Ballester, Ferran

2013-01-01

Objectives To estimate the prevalence and factors associated with smoking and misclassification in pregnant women from INMA (INfancia y Medio Ambiente, Environment and Childhood) project, Spain, and to assess the optimal cut-offs for urinary cotinine (UC) that best distinguish daily and occasional smokers with varying levels of second-hand smoke (SHS) exposure. Design We used logistic regression models to study the relationship between sociodemographic variables and self-reported smoking and misclassification (self-reported non-smokers with UC >50 ng/ml). Receiver operating characteristic (ROC) curves were used to calculate the optimal cut-off point for discriminating smokers. The cut-offs were also calculated after stratification among non-smokers by the number of sources of SHS exposure. The cut-off points used to discriminate smoking status were the level of UC given by Youden's index and for 50 and 100 ng/ml for daily smokers, or 25 and 50 ng/ml for occasional smokers. Participants At the third trimester of pregnancy, 2263 pregnant women of the INMA Project were interviewed between 2004 and 2008 and a urine sample was collected. Results Prevalence of self-reported smokers at the third trimester of pregnancy was 18.5%, and another 3.9% misreported their smoking status. Variables associated with self-reported smoking and misreporting were similar, including born in Europe, educational level and exposure to SHS. The optimal cut-off was 82 ng/ml (95% CI 42 to 133), sensitivity 95.2% and specificity 96.6%. The area under the ROC curve was 0.986 (95% CI 0.982 to 0.990). The cut-offs varied according to the SHS exposure level being 42 (95% CI 27 to 57), 82 (95% CI 46 to 136) and 106 ng/ml (95% CI 58 to 227) for not being SHS exposed, exposed to one, and to two or more sources of SHS, respectively. The optimal cut-off for discriminating occasional smokers from non-smokers was 27 ng/ml (95% CI 11 to 43). Conclusions Prevalence of smoking during pregnancy in

Swelling characteristics of Gaomiaozi bentonite and its prediction

Directory of Open Access Journals (Sweden)

De'an Sun

2014-04-01

Full Text Available Gaomiaozi (GMZ bentonite has been chosen as a possible matrix material of buffers/backfills in the deep geological disposal to isolate the high-level radioactive waste (HLRW in China. In the Gaomiaozi deposit area, calcium bentonite in the near surface zone and sodium bentonite in the deeper zone are observed. The swelling characteristics of GMZ sodium and calcium bentonites and their mixtures with sand wetted with distilled water were studied in the present work. The test results show that the relationship between the void ratio and swelling pressure of compacted GMZ bentonite-sand mixtures at full saturation is independent of the initial conditions such as the initial dry density and water content, but dependent on the ratio of bentonite to sand. An empirical method was accordingly proposed allowing the prediction of the swelling deformation and swelling pressure with different initial densities and bentonite-sand ratios when in saturated conditions. Finally, the swelling capacities of GMZ Na- and Ca-bentonites and Kunigel Na-bentonite are compared.

Cut-off value of body fat in association with metabolic syndrome in Thai peri- and postmenopausal women.

Science.gov (United States)

Bintvihok, W; Chaikittisilpa, S; Panyakamlerd, K; Jaisamrarn, U; Taechakraichana, N

2013-06-01

Pathophysiologic changes during the menopause transition may contribute to the risk of metabolic syndrome (MetS). Body fat composition, particularly visceral fat, is highly associated with increased insulin resistance, abnormal carbohydrate metabolism and high blood pressure. We purposefully wished to determine the optimal cut-off values of body fat composition, including visceral fat, in order to predict MetS and to assess the prevalence of MetS in peri- and postmenopausal women. This cross-sectional study was conducted in a population-based, prospective cohort at the Menopause and Gynecology clinics, King Chulalongkorn Memorial Hospital. Body fat percentage and visceral fat rating were measured by a bioelectrical impedance analyzer (Tanita SC 330). MetS was diagnosed using the Harmonizing criteria of A Joint Interim Statement of IDF/NHLBI/AHA/WHF/IAS/IASO 2009. Receiver operating characteristic analyses were performed to determine the optimal cut-off values of body fat, visceral fat, waist circumference and body mass index to identify peri- and postmenopausal women at risk of MetS. Ninety-two perimenopausal and 446 postmenopausal women aged 40-60 years were recruited for the analyses. The optimal cut-off values for body fat percentage, visceral fat rating, waist circumference and body mass index for identifying women at risk of MetS were 34%, 7, 88 cm and 24 kg/m(2), respectively. The prevalence of MetS in this study was 27.9%. The optimal cut-off values to predict MetS of body fat percentage, visceral fat and waist circumference were established. Using the Harmonizing 2009 criteria, we found that approximately one out of four peri- and postmenopausal women in this study had MetS.

The bentonite industry in North America

International Nuclear Information System (INIS)

Dixon, D.A.; Hnatiw, D.S.J.; Walker, B.T.

1992-11-01

The Canadian Nuclear Fuel Waste Management Program is studying a concept for the disposal of nuclear fuel waste at a depth of 500 to 1000 m below the surface in stable crystalline rock of the Canadian Shield. The waste containers would be surrounded by a clay-based buffer material, composed of equal proportions of bentonite clay and silica sand. In the reference disposal concept, some 1.9 x 10 5 Mg of used fuel would be emplaced. This would require 2.5 x 10 6 Mg of bentonite. A review of the bentonite industry in North America was carried out to establish the availability of sufficient high-quality material. There are proven reserves of sodium bentonite clay in excess of 1.5 x 10 8 Mg, and vast supplies are known to exist but not yet proven. The Canadian conceptual disposal vault would require 6 x 10 4 Mg of sodium bentonite each year for 40 years. The bentonite industry of North America has an installed annual production capacity of 2 x 10 7 Mg. A disposal vault would therefore require approximately 2% of the industry capacity. A number of commercial products have been screened for potential suitability for use as a component of the buffer. Ten currently marketed bentonite products have been identified as meeting the initial quality standards for the buffer, and two non-commercial bentonites have been identified as having the potential for use in a disposal vault. (Author) (14 figs., 7 tabs., 18 refs.)

The application of bentonite in the atomic energy field and some research results of the sorption of uranium on Vietnam bentonite

International Nuclear Information System (INIS)

Than Van Lien; Do Qui Son; Le Thi Kim Dung

2008-01-01

The properties of bentonite can be summarised as follows: low gas permeability, low hydraulic conductivity, high radionuclide retardation capacity, high swelling potential, that is why bentonite has been widely used in the atomic energy fields in many countries all over the world. Vietnam has bentonite deposits that is exploited and used in some fields. In order to use bentonite - available and abandon resources in our country for atomic energy many research activities on the field of bentonite applications have been carried out in Institute for Technology of Radioactive and Rare Elements and Dalat Nuclear Research Institute. In this content, this article introduces the application of bentonite in radioactive waste management and treatment fields (bentonite used as barrier in the deep repository for spent nuclear fuel, as barriers in landfills to prevent contamination of soil and groundwater by leachates containing radioactive, bentonite is also used as sorbent for nuclear reactor activation products (Co, Cr in the waste effluents). At the some time it is present some research results of the sorption of uranium on Vietnamese bentonite. (author)

Evaluation of the amount of excess cement around the margins of cement-retained dental implant restorations: the effect of the cement application method.

Science.gov (United States)

Chee, Winston W L; Duncan, Jesse; Afshar, Manijeh; Moshaverinia, Alireza

2013-04-01

Complete removal of excess cement from subgingival margins after cementation of implant-supported restorations has been shown to be unpredictable. Remaining cement has been shown to be associated with periimplant inflammation and bleeding. The purpose of this study was to investigate and compare the amount of excess cement after cementation with 4 different methods of cement application for cement-retained implant-supported restorations. Ten implant replicas/abutments (3i) were embedded in acrylic resin blocks. Forty complete veneer crowns (CVCs) were fabricated by waxing onto the corresponding plastic waxing sleeves. The wax patterns were cast and the crowns were cemented to the implant replicas with either an interim (Temp Bond) or a definitive luting agent (FujiCEM). Four methods of cement application were used for cementation: Group IM-Cement applied on the internal marginal area of the crown only; Group AH-Cement applied on the apical half of the axial walls of the crown; Group AA-Cement applied to all axial walls of the interior surface of the crown, excluding the occlusal surface; and Group PI-Crown filled with cement then seated on a putty index formed to the internal configuration of the restoration (cementation device) (n=10). Cement on the external surfaces was removed before seating the restoration. Cement layers were applied on each crown, after which the crown was seated under constant load (80 N) for 10 minutes. The excess cement from each specimen was collected and measured. One operator performed all the procedures. Results for the groups were compared, with 1 and 2-way ANOVA and the Tukey multiple range test (α=.05). No significant difference in the amount of excess/used cement was observed between the 2 different types of cements (P=.1). Group PI showed the least amount of excess cement in comparison to other test groups (P=.031). No significant difference was found in the amount of excess cement among groups MI, AH, and AA. Group AA showed the

Bacterial cell wall preservation during organic matter diagenesis in sediments off Peru

DEFF Research Database (Denmark)

Lomstein, Bente Aagaard; Niggemann, Jutta; Jørgensen, Bo Barker

BACTERIAL CELL WALL PRESERVATION DURING ORGANIC MATTER DIAGENESIS IN SEDIMENTS OFF PERU The spatial distribution of total hydrolysable amino acids, total hydrolysable amino sugars and amino acid enantiomers (D- and L-forms) were investigated in surface sediments at 20 stations in the Peru margin: 9......°45 S - 13º32 S. The objective of this study was to assess the preservation of bacterial cell walls during diagenesis of organic matter. Bacterial cell walls were traced by analysis of biomarkers uniquely produced by bacteria (D-amino acids and muramic acid). The diagenetic status of the sediments......:00 Presentation is given by student: No...

Concrete Flow in Diaphragm Wall Panels : A Full-Scale In-Situ Test

NARCIS (Netherlands)

Van Dalen, J.H.; Bosch, J.W.; Broere, W.

2015-01-01

Flow processes, taking place during the concreting of diaphragm wall panels (D-wall panels), are of great importance for the quality of the wall. During this phase, the bentonite, present in the excavated trench, should be completely replaced by concrete in a controlled way. In literature several

A specially designed cut-off gamma camera for high resolution SPECT of the brain

International Nuclear Information System (INIS)

Larsson, S.A.; Bergstrand, G.; Bergstedt, H.; Berg, J.; Flygare, O.; Schnell, P.O.; Anderson, N.; Lagergren, C.

1984-01-01

A modern gamma camera system for Single Photon Emission Computed Tomography (SPECT) has been modified in order to optimize examinations of the head. By cutting off a part of the detector housing at one edge, it has been possible to rotate the camera close to the skull, still covering the entire brain and the skull base. The minimum radius of rotation used was thereby reduced, in the mean, from 21.2 cm to 13.0 cm in examination of 18 patients. In combination with an adjustment of the 64 x 64 acquisition matrix to a field of view of 26x26 cm/sup 2/, the spatial resolution improved from 18.6 mm (FWHM) to 12.6 +- 0.3 mm (FWHM) using the conventional LEGP-collimator and to 10.4 +- 0.3 mm (FWHM) using the LEHR-collimator. No other modification than a slight cut of the light guide was made in the internal construction of the camera. Thus, the physical properties of the detector head are not essentially changed from those of a non-modified unit. The improved spatial resolution of the cut-off camera SPECT-system implies certain clinical advantages in studies of the brain, the cerebrospinal fluid (CSF)-space and the skull base

Suggested cut-off values for vitamin D as a risk marker for total and cardiac death in patients with suspected acute coronary syndrome

Directory of Open Access Journals (Sweden)

Patrycja Anna Naesgaard

2016-02-01

Full Text Available Background: Several studies have demonstrated an association between low vitamin D levels and cardiovascular risk. Vitamin D cut off levels are still under debate. Objectives: To assess two cut-off levels, 40 nmol/L and 70 nmol/L, respectively, for vitamin D measured as 25-hydroxyvitamin D [25(OHD] in chest pain patients with suspected acute coronary syndrome.Methods: We investigated 1853 patients from coastal-Norway and inland Northern-Argentina. A similar database was used for pooling of data. 2-year follow-up data including all-cause mortality, cardiac death and sudden cardiac death in the total patient population were analyzed, applying univariate and multivariable analysis. Results: 255 patients with known vitamin D concentrations died. In the multivariable analysis, there was a decrease in total mortality above a cut-off level of 40 nmol/L and a decrease in cardiac death above a cut-off level of 70 nmol/L, [HRs of 0.66 (95% CI, 0.50 – 0.88, p = 0.004 and 0.46 (95% CI, 0.22 – 0.94, p = 0.034, respectively].Conclusion: Vitamin D cut-off levels of 40 nmol/L and 70 nmol/L, were related to total mortality and cardiac death, respectively.

The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens

DEFF Research Database (Denmark)

Moller, Isabel Eva; de Fine Licht, Henrik Hjarvard; Harholt, Jesper

2011-01-01

communities of microbial and invertebrate symbionts have evolved associations with the dump material from leaf-cutting ant nests, to exploit decomposition niches that the ant garden-fungus does not utilize. Our approach thus provides detailed insight into the nutritional benefits and shortcomings associated......The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus......, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste...

Prediction of pressure of bentonite buffer in model test of disposal pit for high-level radioactive waste

International Nuclear Information System (INIS)

Komine, Hideo; Osada, Toru; Takao, Hajime; Ueda, Hiroyoshi

2013-01-01

Bentonite-based buffer materials for high-level radioactive waste (HLW) disposal are expected to fill up the space between buffer and a wall of the disposal pit, and/or between buffer and an waste-container called as overpack by its swelling deformation. That is called as self-sealing ability. This study performs the model tests simulated the relationship between buffer and space mentioned above. It also investigates the validity of the theoretical equations for evaluating the swelling characteristics of bentonite-based buffer and backfill material, which were proposed in Komine and Ogata (2003, 2004), by comparing the calculations and the experimental results. (author)

Refining Game Addiction Questionnairs: Evidence for a natural cut-off point?

OpenAIRE

Nielsen, Rune Kristian

2013-01-01

This paper presents data from a pilot study, which was designed to illuminate critical flaws in the currently used instruments used to measure the prevalence of ‘computer game addiction’. The study found that the prevalence rate could be set anywhere between 23% and 0,6% depending on how the data set is scored. Thus demonstrating how an arbitrarily set of cut-off point in prevalence studies can yield wildly varying prevalence rates. The data further show that making implicit assumptions about...

Hydraulic conductivity of some bentonites in artificial seawater

International Nuclear Information System (INIS)

Komine, Hideo; Murakami, Satoshi; Yasuhara, Kazuya

2011-01-01

A high-level radioactive waste disposal facility might be built in a coastal area in Japan from the viewpoint of feasible transportation of waste. Therefore, it is important to investigate the effects of seawater on a bentonite-based buffer. This study investigated the influence of seawater on hydraulic conductivity of three common sodium-types of bentonite and one calcium-type bentonite by the laboratory experiments. >From the results of laboratory experiment, this study discussed the influence of seawater on hydraulic conductivity of bentonites from the viewpoints of kinds of bentonite such as exchangeable-cation type and montmorillonite content and dry density of bentonite-based buffer. (author)

Addenbrooke's Cognitive Examination and Individual Domain Cut-Off Scores for Discriminating between Different Cognitive Subtypes of Parkinson's Disease.

Science.gov (United States)

Berankova, Dagmar; Janousova, Eva; Mrackova, Martina; Eliasova, Ilona; Kostalova, Milena; Skutilova, Svetlana; Rektorova, Irena

2015-01-01

Objective. The main aim of this study was to verify the sensitivity and specificity of Addenbrooke's Cognitive Examination-Revised (ACE-R) in discriminating between Parkinson's disease (PD) with normal cognition (PD-NC) and PD with mild cognitive impairment (PD-MCI) and between PD-MCI and PD with dementia (PD-D). We also evaluated how ACE-R correlates with neuropsychological cognitive tests in PD. Methods. We examined three age-matched groups of PD patients diagnosed according to the Movement Disorder Society Task Force criteria: PD-NC, PD-MCI, and PD-D. ROC analysis was used to establish specific cut-off scores of ACE-R and its domains. Correlation analyses were performed between ACE-R and its subtests with relevant neuropsychological tests. Results. Statistically significant differences between groups were demonstrated in global ACE-R scores and subscores, except in the language domain. ACE-R cut-off score of 88.5 points discriminated best between PD-MCI and PD-NC (sensitivity 0.68, specificity 0.91); ACE-R of 82.5 points distinguished best between PD-MCI and PD-D (sensitivity 0.70, specificity 0.73). The verbal fluency domain of ACE-R demonstrated the best discrimination between PD-NC and PD-MCI (cut-off score 11.5; sensitivity 0.70, specificity 0.73) while the orientation/attention subscore was best between PD-MCI and PD-D (cut-off score 15.5; sensitivity 0.90, specificity 0.97). ACE-R scores except for ACE-R language correlated with specific cognitive tests of interest.

Finite GUE Distribution with Cut-Off at a Shock

Science.gov (United States)

Ferrari, P. L.

2018-03-01

We consider the totally asymmetric simple exclusion process with initial conditions generating a shock. The fluctuations of particle positions are asymptotically governed by the randomness around the two characteristic lines joining at the shock. Unlike in previous papers, we describe the correlation in space-time without employing the mapping to the last passage percolation, which fails to exists already for the partially asymmetric model. We then consider a special case, where the asymptotic distribution is a cut-off of the distribution of the largest eigenvalue of a finite GUE matrix. Finally we discuss the strength of the probabilistic and physically motivated approach and compare it with the mathematical difficulties of a direct computation.

The mechanical and physical behaviour on the cemented waste forms after one year disposal of real conditions

International Nuclear Information System (INIS)

Bucataru-Nicu, M.; Mihai, F.; Rotarescu, Gh.; Turcanu, C.N.; Lungu, L.

1999-01-01

To prove the durability of cemented waste forms, an experimental program started in 1997 to establish the alteration in time of mechanical and physic-chemical properties of different simulated and real matrices in laboratory and Baita-Bihor disposal conditions. The selected matrices for characterization are normal cement and concrete compositions with and without mineral additives (bentonite and volcanic tuff) as reference samples, the conditioned matrices prepared with radioactive sludge non-active components (iron hydroxides and phosphate, calcium phosphate and cooper ferrocyanide) and non-active matrices prepared with organic acids and salts (oxalic, citric, tartaric, EDTA). All samples will be positioned in five locations of Baita-Bihor repository and kept 1, 3, 5 and 10 years before mechanical and structural characterization. These locations have different humidity conditions decreasing from location 1 to 5. These results will be compared with results obtained for the same type of samples kept in laboratory conditions. The research program requires detailed identification of the complex phenomena involved, long investigation times and extending basic data determined from laboratory tests in simplified conditions. The basic information on the waste matrix are obtained by mechanical strength tests. In this program, up to now, samples were prepared and disposed as follows: 1)cement-water with cement/water ratio 2:1 and 2)cement-sand-water with a cement/sand/water ratio 1:2:0.5. For the mechanical tests the sizes of the samples were: 40 x 40 x 160 mm (tested at bending and compression) and 20 x 20 x 20 mm (tested at compression). After the preparation, the samples were kept 24 hours in pattern, then in tight plastic bag for 7, 14 and 28 days for reinforcement. The bending and compression tests were done in a construction materials laboratory, using an electric press machine. After 28 days the samples of reference were introduced in the National Repository. Some of

MANU. Handling of bentonite prior buffer block manufacturing

International Nuclear Information System (INIS)

Laaksonen, R.

2010-01-01

The aim of this study is to describe the entire bentonite handling process starting from freight from harbour to storage facility and ending up to the manufacturing filling process of the bentonite block moulds. This work describes the bentonite handling prior to the process in which bentonite blocks are manufactured in great quantities. This work included a study of relevant Nordic and international well documented cases of storage, processing and techniques involving bentonite material. Information about storage and handling processes from producers or re-sellers of bentonite was collected while keeping in mind the requirements coming from the Posiva side. Also a limited experiment was made for humidification of different material types. This work includes a detailed description of methods and equipment needed for bentonite storage and processing. Posiva Oy used Jauhetekniikka Oy as a consultant to prepare handling process flow charts for bentonite. Jauhetekniikka Oy also evaluated the content of this report. The handling of bentonite was based on the assumption that bentonite process work is done in one factory for 11 months of work time while the weekly volume is around 41-45 tons. Storage space needed in this case is about 300 tons of bentonite which equals about seven weeks of raw material consumption. This work concluded several things to be carefully considered: sampling at various phases of the process, the air quality at the production/storage facilities (humidity and temperature), the level of automation/process control of the manufacturing process and the means of producing/saving data from different phases of the process. (orig.)

Adiposity cut-off points for cardiovascular disease and diabetes risk in the Portuguese population: The PORMETS study

Science.gov (United States)

Severo, Milton; Santos, Ana Cristina

2018-01-01

Objectives The contribution of adiposity to cardiovascular and diabetes risk justifies the inclusion of an adiposity measure, usually waist circumference, in the definition of metabolic syndrome. However, waist circumference thresholds differ across populations. Our aim was to assess which adiposity measure performs the best in identifying the metabolic syndrome in a sample of Portuguese participants and to estimate cut-off values for these measures. Methods Data were obtained from a cross-sectional study (PORMETS study) conducted in Portugal between 2007 and 2009. A representative sample of non-institutionalized adults, comprising 3,956 participants, aged 18 years and older, was evaluated. A structured questionnaire was administered, collecting information on personal medical history, socio-demographics and behavioral characteristics. Anthropometrics, blood pressure and venous blood samples were also obtained. Metabolic syndrome was defined according to the Joint Interim Statement of the International Diabetes Federation Task Force on Epidemiology recommended criteria. Elevated cardiometabolic risk was considered when two or more of the four criteria of metabolic syndrome were present, excluding the waist circumference component. A receiver operating characteristic curve was used to estimate cut-off points. Results This study found that waist-to-height ratio, waist circumference and body adiposity index performed better than other adiposity measures, such as body mass index. The estimated cut-off points for waist-to-height ratio, waist circumference and body adiposity index in women and men were 0.564 / 89 cm / 27.4 and 0.571 / 93.5 cm / 25.5, respectively. Conclusion As waist circumference is currently used as the adiposity measure in the definition of metabolic syndrome and as no relevant differences were observed between this measure and waist-to-height ratio, it is likely that no modification to the metabolic syndrome definition needs to be proposed. Moreover

Cut-Off Value for Pain Sensitivity Questionnaire in Predicting Surgical Success in Patients with Lumbar Disc Herniation.

Directory of Open Access Journals (Sweden)

Parisa Azimi

Full Text Available Various factors related to predict surgical success were studied; however, a standard cut-off point for the Pain Sensitivity Questionnaire (PSQ measure has not yet been established for a favorable surgical outcome for lumbar disc herniation (LDH. This study was to find the optimal cut-off point on the PSQ to distinguish surgical success in patients with LDH. A total of 154 patients with LDH consecutively referred to our clinic were enrolled into this prospective study between February 2011 and January 2014. All participants completed the PSQ. Patients completed the Oswestry Disability Index (ODI score before surgery, and at 2 years after surgery. Surgical success was defined as a 13-point improvement from the baseline ODI scores. The cut-off value for PSQ was determined by the receiver-operating characteristic curve (ROC. The mean age of patients was 49.3±9.6 years, and there were 80 women. The mean time for follow-up assessment was 31±5 months (range 24-35. Post-surgical success was 79.9% (n = 123 at 2 years follow up. The mean score for the total PSQ, PSQ-minor, and PSQ-moderate were 6.0 (SD = 1.6, 5.4 (SD = 1.9 and 6.5 (SD = 1.7, respectively. Total PSQ score was also significantly correlated with the total scores of the ODI. The optimal total PSQ cut-off point was determined as > 5.2 to predict surgical success in LDH patients, with 80.0% sensitivity and 75.6% specificity (AUC-0.814, 95% CI 0.703-0.926. This study showed that the PSQ could be considered a parameter for predicting surgical success in patients with LDH, and can be useful in clinical practice.

Gas migration characteristics of highly compacted bentonite ore

International Nuclear Information System (INIS)

Tanaka, Yukihisa; Hironaga, Michihiko

2010-01-01

In the current concept of repository for radioactive waste disposal, compacted bentonite will be used as an engineered barrier mainly for inhibiting migration of radioactive nuclides. Hydrogen gas can be generated inside the engineered barrier by anaerobic corrosion of metals used for containers, etc. If the gas generation rate exceeds the diffusion rate of dissolved gas inside of the engineered barrier, gas will accumulate in the void space inside of the engineered barrier until its pressure becomes large enough for it to enter the bentonite as a discrete gaseous phase. It is expected to be not easy for gas to entering into the bentonite as a discrete gaseous phase because the pore of compacted bentonite is so minute. Gas migration characteristics of highly compacted powdered bentonite are already reported by CRIEPI. In this report, gas migration characteristics of bentonite ore, which is a candidate for construction material of repository for radioactive waste, is investigated. The following conclusions are obtained through the results of the gas migration tests which are conducted in this study: 1) When the total gas pressure exceeds the initial total axial stress, the total axial stress is always equal to the total gas pressure because specimens shrink in the axial direction with causing the clearance between the end of the specimen and porous metal. By increasing the gas pressure more, gas breakthrough, which defined as a sudden and sharp increase in gas flow rate out of the specimen, occurs. Therefore gas migration mechanism of compacted bentonite ore is basically identical to that of compacted powdered bentonite. 2) Hydraulic conductivity measured after the gas breakthrough is somewhat smaller than that measured before the gas migration test. This fact means that it might be possible to neglect decline of the function of bentonite as engineered barrier caused by the gas breakthrough. These characteristics of compacted bentonite ore are identical to those of

The cut-off values of anthropometric variables for predicting mild cognitive impairment in Malaysian older adults: a large population based cross-sectional study

Directory of Open Access Journals (Sweden)

Won H

2017-02-01

Full Text Available Huiloo Won,1 Zahara Abdul Manaf,2 Arimi Fitri Mat Ludin,3 Mohd Azahadi Omar,4 Rosdinom Razali,5 Suzana Shahar2 1Nutrition Program, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 2Dietetics Program, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 3Biomedical Science Program, School of Diagnostic and Applied Health Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 4Centre for Burden of Disease Research, Institute for Public Health, Ministry of Health Malaysia, 5Department of Psychiatry, Faculty of Medicine, Hospital Canselor Tuanku Muhriz, University Kebangsaan Malaysia, Kuala Lumpur, Malaysia Purpose: Older adults are at risk of mild cognitive impairment (MCI, and simple anthropometric measurements can be used to screen for this condition. Thus, the aim of this study was to explore the cut-off values of body mass index (BMI and waist circumference (WC for predicting the risk of MCI in older Malaysian adults.Methods: A total of 2,240 Malaysian older adults aged ≥60 years were recruited using multistage random sampling in a population based cross-sectional study. Receiver operating characteristic (ROC curve was used to determine the cut-off values of BMI and WC with optimum sensitivity and specificity for the detection of MCI. Age, gender, years of education, smoking habit, alcohol consumption, depression, and medical conditions were used as confounding factors in this analysis.Results: A BMI cut-off value of 26 kg/m2 (area under the receiver operating characteristic curve [AUC] 0.725; sensitivity 90.5%; specificity 38.8% was appropriate in identifying the risk of getting MCI in both men and women. The optimum WC cut-offs for likelihood of MCI were 90 cm (AUC 0.745; sensitivity 78.0%; specificity 59.8% for men and 82 cm (AUC 0.714; sensitivity 84.3%; specificity 49.7% for women. The optimum calf circumference (CC cut-off values for identifying MCI were 29 cm (AUC 0.731; sensitivity 72.6%; specificity

Study of reuse drill cuttings as aggregate in the civil construction industry; Estudo para reaproveitamento do cascalho de perfuracao como agregado na industria da construcao civil

Energy Technology Data Exchange (ETDEWEB)

Neder, L.T.C. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Exploracao e Producao. Seguranca, Meio Ambiente e Saude; Santos, E.; Bezerra, M.T.A.; Farias, J.G.; Felizardo, A.; Santos, A.S.; Ribeiro, J.C. [PETROBRAS, Natal/Fortaleza, RN/CE (Brazil). Unidade de Negocio; Curti, R.; Suto, A.J. [Associacao Brasileira de Cimento Portland, Jaguare, SP (Brazil)

2004-07-01

This study was conducted to verify technical feasibility in reusing drill cuttings originated in oil and gas exploration and production to produce concrete or mortar elements. It consisted of physical and chemical characterization of all items used to build field-cured cement samples - drill cuttings, cement and used aggregates; evaluation of resistance; environmental behavior and classification of the resultant materials. The results had demonstrated the reuse of drill cuttings is possible from both technical and environmental perspective and the ratio of concrete or mortar can be customized according to physical and mechanical needs of end products. In the civil construction elements can be built and used as road basis, ground-cement base, blocks and bricks and other non-structural elements. The application of these elements in E and P operations include containment walls for onshore wells, collecting stations, pipeline brackets, supports and hold-down anchors as well as road pavement and access. From the standpoint of chemical safety, the resultant elements made-up from drill cuttings had demonstrated no potential risk for hydrocarbon leaching (TPH), Polycyclic Aromatic Hydrocarbons (PAH's), Volatile Organic Compounds (BTEX), Phenols nor Metals. From these results many improvements in the E and P waste management can be established, bringing both economy and greater environment protection measures for the Oil and Gas Exploration and Production operations. (author)

Roles of bentonite in radioactive waste disposal

International Nuclear Information System (INIS)

Suzuki, Keizo

1995-01-01

Bentonite is used in radioactive waste disposal from the following points; (1) properties (2) now utilization fields (3) how to use in radioactive waste disposal (4) how much consumption and deposits as source at the present time. Bentonite is produced as alteration products from pyroclastic rocks such as volcanic ash and ryolite, and is clay composed mainly smectite (montmorillonite in general). Therefore, special properties of bentonite such as swelling potential, rheological property, bonding ability, cation exchange capacity and absorption come mainly from properties of montmorillonite. Bentonite has numerous uses such as iron ore pelleizing, civil engineering, green sand molding, cat litter, agricultural chemicals and drilling mud. Consumption of bentonite is about 600-700 x 10 3 tons in Japan and about 10 x 10 6 tons in the world. Roles of bentonite to be expected in radioactive waste disposal are hydraulic conductivity, swelling potential, absorption, mechanical strength, ion diffusion capacity and long-term durability. These properties come from montmorillonite. (author)

Chitosan/bentonite bionanocomposites: morphology and mechanical behavior

International Nuclear Information System (INIS)

Braga, C.R.C.; Melo, F.M.A. de; Vitorino, I.F.; Fook, M.V.L.; Silva, S.M.L.

2010-01-01

This study chitosan/bentonite bionanocomposite films were prepared by solution intercalation process, seeking to investigate the effect of the chitosan/bentonite ratio (5/1 e 10/1) on the morphology and mechanical behavior of the bionanocomposites. It was used as nanophase, Argel sodium bentonite (AN), was provided by Bentonit Uniao Nordeste-BUN (Campina Grande, Brazil) and as biopolymer matrix the chitosan of low molecular weight and degree of deacetylation of 86,7% was supplied by Polymar (Fortaleza, Brazil). The bionanocomposites was investigated by X-ray diffraction and tensile properties. According to the results, the morphology and the mechanical behavior of the bionanocomposite was affected by the ratio of chitosan/bentonite. The chitosan/bentonite ratio (5/1 and 10/1) indicated the formation of an intercalated nanostructure and of the predominantly exfoliated nanostructure, respectively. And the considerable increases in the resistance to the traction were observed mainly for the bionanocomposite with predominantly exfoliated morphology. (author)

Practical use of visual medial temporal lobe atrophy cut-off scores in Alzheimer's disease: Validation in a large memory clinic population

Energy Technology Data Exchange (ETDEWEB)

Claus, Jules J.; Holl, Dana C.; Roorda, Jelmen J. [Tergooi Hospital, Department of Neurology, Blaricum (Netherlands); Staekenborg, Salka S. [Tergooi Hospital, Department of Neurology, Blaricum (Netherlands); VU University Medical Center, Department of Neurology, Alzheimer Center, Amsterdam (Netherlands); Schuur, Jacqueline [Tergooi Hospital, Department of Geriatrics, Blaricum (Netherlands); Koster, Pieter [Tergooi Hospital, Department of Radiology, Blaricum (Netherlands); Tielkes, Caroline E.M. [Tergooi Hospital, Department of Medical Psychology, Blaricum (Netherlands); Scheltens, Philip [VU University Medical Center, Department of Neurology, Alzheimer Center, Amsterdam (Netherlands)

2017-08-15

To provide age-specific medial temporal lobe atrophy (MTA) cut-off scores for routine clinical practice as marker for Alzheimer's disease (AD). Patients with AD (n = 832, mean age 81.8 years) were compared with patients with subjective cognitive impairment (n = 333, mean age 71.8 years) in a large single-centre memory clinic. Mean of right and left MTA scores was determined with visual rating (Scheltens scale) using CT (0, no atrophy to 4, severe atrophy). Relationships between age and MTA scores were analysed with regression analysis. For various MTA cut-off scores, decade-specific sensitivity and specificity and area under the curve (AUC) values, computed with receiver operator characteristic curves, were determined. MTA strongly increased with age in both groups to a similar degree. Optimal MTA cut-off values for the age ranges <65, 65-74, 75-84 and ≥85 were: ≥1.0, ≥1.5, ≥ 2.0 and ≥2.0. Corresponding values of sensitivity and specificity were 83.3% and 86.4%; 73.7% and 84.6%; 73.7% and 76.2%; and 84.0% and 62.5%. From this large unique memory clinic cohort we suggest decade-specific MTA cut-off scores for clinical use. After age 85 years, however, the practical usefulness of the MTA cut-off is limited. (orig.)

Thermo-mechanical cementation effects in bentonite investigated by unconfined compression tests

International Nuclear Information System (INIS)

Dueck, Ann; Boergesson, Lennart; Karnland, Ola

2010-01-01

Document available in extended abstract form only. Mechanical properties of buffer material are included in the model used for predicting the physical behaviour of saturated buffer in the final disposal of spent nuclear fuel. One simple test where the mechanical properties can be quantified is the unconfined compression test. In this type of test the relation between stress and strain are determined from axial compression of a cylindrical specimen. In the project LOT the unconfined compression test was used to study the mechanical properties on field exposed buffer material. The results from these test series showed that specimens exposed to warm conditions had a significantly reduced strain at failure compared to reference material. Changes in mechanical properties may be due to incipient chemical changes in the material. However, the present study focuses on other possible sources for brittle failure behaviour. In this study the objective was to experimentally investigate if deviating stress-strain behaviour measured after temperature exposure could be explained by Thermo-Hydro-Mechanical processes. The word cementation is used as a general term for the process involving a change in mechanical properties including brittleness at failure. A relatively large number of specimens were tested representing sodium dominated and calcium dominated bentonites. Cylindrical specimens were compacted from air dry powder to a height and diameter of 20 mm. The main part of the specimens was put in a saturation device prior to the tests in order to ensure full saturation. After the saturation each sample was placed in a mechanical press where a constant rate of strain was applied axially to the specimens having no radial confinement. During the test the deformation and the applied force were measured by means of force and strain transducers. After failure the water content and density were determined. Test series were carried out for investigating the influence of for example

Thermo-Hydro-Mechanical Characterisation of the Bentonite of a Simulated HLW Repository after Five Years Operation ( In Situ Test of the FEBEX Project)

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.

2004-07-01

After five years of operation, heater 1 of the FEBEX experimental at the Grimsel Test Sites was switched off in February 2002. Following cooling of the system, the bentonite barrier was dismantled and the heater extracted. During dismantling many bentonite samples were taken. Several determinations were carried out in these samples with the aim of: (1) characterise the actual state of the bentonite and (2) determine the possible changes in its properties occurred during the experiment. The results of the thermo-hydro-mechanical characterisation performed at CIEMAT are reported and analysed. The distribution of water content and dry density of the bentonite in vertical sections presents axial symmetry. The construction gaps of the barrier have been filled by the expansion of the bentonite. The water retention capacity, the hydraulic conductivity and the swelling capacity of the samples from Grimsel have not irreversible changed. The pre consolidation pressure of the Grimsel samples has decreased due to the microstructural changes associated to the volume increase experienced during hydration. The thermal conductivity is higher for the bentonite blocks of the external ring of the barrier. (Author)

Thermo-Hydro-Mechanical Characterisation of the Bentonite of a Simulated HLW Repository after Five Years Operation ( In Situ Test of the FEBEX Project)

International Nuclear Information System (INIS)

Villar, M. V.

2004-01-01

After five years of operation, heater 1 of the FEBEX experimental at the Grimsel Test Sites was switched off in February 2002. Following cooling of the system, the bentonite barrier was dismantled and the heater extracted. During dismantling many bentonite samples were taken. Several determinations were carried out in these samples with the aim of: (1) characterise the actual state of the bentonite and (2) determine the possible changes in its properties occurred during the experiment. The results of the thermo-hydro-mechanical characterisation performed at CIEMAT are reported and analysed. The distribution of water content and dry density of the bentonite in vertical sections presents axial symmetry. The construction gaps of the barrier have been filled by the expansion of the bentonite. The water retention capaciaty, the hydraulic conductivity and the swelling capacity of the samples from Grimsel have not irreversible changed. The preconsolidation pressure of the Grimsel samples has decreased due to the microstructural changes asswociated to the volume increase experienced during hydration. The thermal conductivity is higher for the bentonite blocks of the external ring of the barrier. (Author)

Adsorption of La(III) onto GMZ bentonite. Effect of contact time, bentonite content, pH value and ionic strength

International Nuclear Information System (INIS)

Yonggui Chen; Changsha University of Science and Technology, Changsha; Chunming Zhu; Weimin Ye; Yanhong Sun; Huiying Duan; Dongbei Wu

2012-01-01

Bentonite has been studied extensively because of its strong adsorption capacity. A local Na-bentonite named GMZ bentonite, collected from Gaomiaozi County (Inner Mongolia, China), was selected as the first choice of buffer/backfill material for the high-level radioactive waste repository in China. In this research, the adsorption of La (III) onto GMZ bentonite was performed as a function of contact time, pH, solid content and metal ion concentrations by using the batch experiments. The results indicate that the adsorption of La (III) on GMZ bentonite achieves equilibration quickly and the kinetic adsorption follows the pseudo-second-order model; the adsorption of La (III) on the adsorbent is strongly dependent on pH and solid content, the adsorption process follows Langmuir isotherm. The equilibrium batch experiment data demonstrate that GMZ bentonite is effective adsorbent for the removal of La (III) from aqueous solution with the maximum adsorption capacity of 26.8 mg g -1 under the given experimental conditions. (author)

Insulin resistance in obese children and adolescents: HOMA-IR cut-off levels in the prepubertal and pubertal periods.

Science.gov (United States)

Kurtoğlu, Selim; Hatipoğlu, Nihal; Mazıcıoğlu, Mümtaz; Kendirici, Mustafa; Keskin, Mehmet; Kondolot, Meda

2010-01-01

Childhood obesity is associated with an increased risk for insulin resistance. The underlying mechanism for the physiological increase in insulin levels in puberty is not clearly understood. The aim of the present study was to determine the cut-off values for homeostasis model assessment for insulin resistance (HOMA-IR) in obese children and adolescents according to gender and pubertal status. Two hundred and eight obese children and adolescents (141 girls, 127 boys) aged between 5 and 18 years were included in the study. The children were divided into prepubertal and pubertal groups. A standard oral glucose tolerance test (OGTT) was carried out in all children. A total insulin level exceeding 300 μU/mL in the blood samples, collected during the test period, was taken as the insulin resistance criterion. Cut-off values for HOMA-IR were calculated by receiver operating characteristic (ROC) analysis. In the prepubertal period, the rate of insulin resistance was found to be 37% in boys and 27.8% in girls,while in the pubertal period, this rate was 61.7% in boys and 66.7% in girls. HOMA-IR cut-off values for insulin resistance in the prepubertal period were calculated to be 2.67 (sensitivity 88.2%, specificity 65.5%) in boys and 2.22 (sensitivity 100%, specificity 42.3%) in girls, and in the pubertal period, they were 5.22 (sensitivity 56%, specificity 93.3%) in boys and 3.82 (sensitivity 77.1%, specificity 71.4%) in girls. Since gender, obesity and pubertal status are factors affecting insulin resistance, cut-off values which depend on gender and pubertal status, should be used in evaluation of insulin resistance.

Putative Dementia Cases Fluctuate as a Function of Mini-Mental State Examination Cut-Off Points.

Science.gov (United States)

Rosa, Ilka M; Henriques, Ana G; Wiltfang, Jens; da Cruz E Silva, Odete A B

2018-01-01

As the population ages, there is a growing need to quickly and accurately identify putative dementia cases. Many cognitive tests are available; among those commonly used are the Cognitive Dementia Rating (CDR) and the Mini-Mental Status Examination (MMSE). The aim of this work was to compare the validity and reliability of these cognitive tests in a primary care based cohort (pcb-Cohort). The MMSE and the CDR were applied to 568 volunteers in the pcb-Cohort. Distinct cut-off points for the MMSE were considered, namely MMSE 27, MMSE 24, and MMSE PT (adapted for the Portuguese population). The MMSE 27 identified the greatest number of putative dementia cases, and, as determined by the ROC curve, it was the most sensitive and specific of the MMSE cut-offs considered. Putative predictive or risk factors identified included age, literacy, depression, and diabetes mellitus (DM). DM has previously been indicated as a risk factor for dementia and Alzheimer's disease. Comparatively, the MMSE 27 cut-off has the greatest sensibility (94.9%) and specificity (66.3%) when compared to MMSE PT and MMSE 24. Upon comparing MMSE and CDR scores, the latter identified a further 146 putative dementia cases, thus permitting one to propose that in an ideal situation, both tests should be employed. This increases the likelihood of identifying putative dementia cases for subsequent follow up work, thus these cognitive tests represent important tools in patient care. Further, this is a significant study for Portuguese populations, where few of these studies have been carried out.

Use of cut-off values as meaningfulness limits in probabilistic studies and its effect on NPPs risk assessment and safety improvement

International Nuclear Information System (INIS)

Petrangeli, G.; Valeri, A.; Zaffiro, C.

1991-01-01

This paper discusses the use of cut-off values in probabilistic risk assessment/probabilistic safety assessment (PRA/PSA) of nuclear power plants (NPPs), in order to explore under which conditions this practice may help improve the meaningfulness of the results of the analyses and safety of plants, and how it may affect the assessment of risk. Reference is made, in particular, to some past practical applications, also taken from the experience of the authors within the frame of the Italian licensing process. The paper describes the Italian probabilistic criteria which use probabilistic targets and cut-off values to assess safety and identify plant safety improvements. The rationale of the approach is also discussed in the paper and results of sample applications are illustrated. The paper concludes that the use of cut-off values, if properly implemented, could be productive to improve the plant safety as it helps the analyst to focus on a restricted field of analysis, ignoring lower probability and less known events. It also points out that cut-off values should be considered as living numbers to be lowered and even eliminated as soon as significant advancements are made, through research and operational experience, in the knowledge of the pertinent events

The Potential of Established Fitness Cut-off Points for Monitoring Women with Fibromyalgia: The al-Ándalus Project.

Science.gov (United States)

Castro-Piñero, José; Aparicio, Virginia A; Estévez-López, Fernando; Álvarez-Gallardo, Inmaculada C; Borges-Cosic, Milkana; Soriano-Maldonado, Alberto; Delgado-Fernández, Manuel; Segura-Jiménez, Víctor

2017-05-01

The aim of the present study was to determinate whether fitness cut-off points discriminate the severity of major fibromyalgia symptoms and health-related quality of life. Additionally, we investigated which American Colleague of Rheumatology (ACR) fibromyalgia criteria (1990 vs. modified 2010) better discriminate fibromyalgia symptomatology. A total of 488 women with fibromyalgia and 200 non-fibromyalgia (control) women participated. All participants underwent both the 1990 and the modified 2010 ACR preliminary criteria (hereinafter 1990c and m-2010c, respectively). We used fitness cut-off points (Senior Fitness Tests Battery plus handgrip strength test) to discriminate between presence and absence of fibromyalgia. Additionally, we employed several instruments to assess fibromyalgia symptoms. Fitness cut-off points discriminated between high and low levels of the main symptoms the disease in all age groups (P from fibromyalgia diagnosis and monitoring. Moreover, the effect size of the differences in symptoms between women with fibromyalgia and controls were overall larger using the m-2010c compared with the 1990c, except for the tender points count, reflecting better the polysymptomatic distress condition of fibromyalgia. © Georg Thieme Verlag KG Stuttgart · New York.

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

International Nuclear Information System (INIS)

Sitompul, Johnner; Setyawan, Daru; Kim, Daniel Young Joon; Lee, Hyung Woo

2016-01-01

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were then characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

Energy Technology Data Exchange (ETDEWEB)

Sitompul, Johnner, E-mail: sitompul@che.itb.ac.id; Setyawan, Daru, E-mail: daru.setyawan@gmail.com; Kim, Daniel Young Joon, E-mail: daniel.kim12321@gmail.com [Department of Chemical Engineering, Faculty of Industrial Technology, Institute of Technology Bandung Jl. Ganesha 10, Bandung, West Java, 40132 (Indonesia); Lee, Hyung Woo, E-mail: leehw@che.itb.ac.id [Department of Chemical Engineering, Faculty of Industrial Technology, Institute of Technology Bandung Jl. Ganesha 10, Bandung, West Java, 40132 (Indonesia); Research and Business Foundation, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 440-746 (Korea, Republic of)

2016-04-19

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were then characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.

Physical and cut-off effects of heavy sea quarks

CERN Document Server

Knechtli, Francesco; Bruno, Mattia; Finkenrath, Jacob; Leder, Björn; Marinkovic, Marina; Sommer, Rainer

2014-01-01

We simulate a theory with two dynamical O($a$) improved Wilson quarks whose mass $M$ ranges from a factor eight up to a factor two below the charm quark mass and at three values of the lattice spacing ranging from 0.066 to 0.034 fm. This theory is a prototype to study the decoupling of heavy quarks. We measure the mass and cut-off dependence of ratios of gluonic observables defined from the Wilson flow or the static potential. The size of the 1/$M$ corrections can be determined and disentangled from the lattice artifacts. The difference with the pure gauge theory is at the percent level when two quarks with a mass of the charm quark are present.

Fabrication and handling of bentonite blocks

International Nuclear Information System (INIS)

1978-06-01

In accordance with the project for the final storage of spent nuclear fuel, the waste will be encapsulated into copper canisters, which will be deposited in a final repository located in rock 500 m below ground level. The canisters will be placed in vertical holes in the bottoms of the tunnels, where the copper cylinders will be surrounded by blocks of highly compacted bentonite. When the blocks are saturated with water and expansion is essentially retained as in the actual case, a very high swelling pressure will arise. The bentonite will be extremely impermeable and thus it will form a barrier against transport of corrosive matters to the canister. The blocks are fabricated by means of cold isostatic pressing of bentonite powder. The base material in the form of powder is enclosed in flexible forms, which are introduced into pressure vessels where the forms are surrounded by oil or water. Thus the powder is compacted into rigid bodies with a bulk density of about 2.2 t/m 3 for ''air dry'' bentonite, which might be compared with a specific density of about 2.7 t/m 3 . The placing of a canister is preceded by piling up bentonite blocks to a level just below the canister lid position, after which the slot around the blocks is filled with bentonite powder. The rest of the blocks are mounted after filling bentonite powder into the inner slot around the canister as well. Finally the storage tunnels will be sealed by filling them with a mixture o02067NRM 0000181 45

Attenuation bands and cut-off frequencies for ELF electromagnetic waves

International Nuclear Information System (INIS)

Rauch, J.L.; Lefeuvre, F.; Cerisier, J.C.; Berthelier, J.J.; Boud'ko, N.; Michailova, G.; Kapustina, O.

1985-01-01

The propagation characteristic of ELF (10 Hz - 1500 Hz) electromagnetic waves observed on ARCAD 3, in three different zones: low L value (L 6). Unambiguous determinations of the wave normal directions are obtained from the interpretations of the measurements of four (3 magnetic, 1 electric) wave field components. The technique that is used, is based on the Means method in the cases of highly polarized waves and on the Storey and Lefeuvre WDF method in the other cases. A particular emphasis is put on the propagation characteristics of the waves, in a multiple ion plasma, and on the cut-off frequencies which appear at and below the local proton gyrofrequency

Activation of wine bentonite with gamma rays

International Nuclear Information System (INIS)

Goranov, N.; Antonov, M.

1997-01-01

The action of gamma rays on wine bentonite as well as influence of its adsorption and technologic qualities on the composition and stability of wines against protein darkening and precipitation has been studied. The experiments were carried out with wine bentonite produced in the firm Bentonite and irradiated with doses of 0.4, 0.6, 0.8 and 1.0 MR. White and red wines have been treated with irradiated bentonite under laboratory conditions at 1.0 g/dm 3 . All samples are treated at the same conditions. The flocculation rate of the sediment was determined visually. Samples have been taken 24 h later from the cleared wine layers. The following parameters have been determined: clarification, filtration rate, phenolic compounds, calcium, colour intensity, total extracted substances, etc. The volume of the sediment has been determined also. The control samples have been taken from the same unirradiated wines. The results showed better and faster clarification in on the third, the 20th and the 24th hours with using of gamma-irradiated at doses 0.8 and 1.0 MR. The sediment was the most compact and its volume - the smallest compared to the samples treated with bentonite irradiated with doses of 0.6 and 0.4 MR. This ensures a faster clarification and better filtration of treated wines. The bentonite activated with doses of 0.8 and 1.0 MR adsorbs the phenolic compounds and the complex protein-phenolic molecules better. In the same time it adsorbs less extracted substances compared to untreated bentonite and so preserves all organoleptic properties of wine. The irradiated bentonite adsorbs less the monomers of anthocyan compounds which ensures brighter natural colour of wine. The gamma-rays activation consolidates calcium in the crystal lattice of bentonite particles and in this way eliminates the formation of crystal precipitates

Flocking of the Motsch-Tadmor Model with a Cut-Off Interaction Function

Science.gov (United States)

Jin, Chunyin

2018-04-01

In this paper, we study the flocking behavior of the Motsch-Tadmor model with a cut-off interaction function. Our analysis shows that connectedness is important for flocking of this kind of model. Fortunately, we get a sufficient condition imposed only on the model parameters and initial data to guarantee the connectedness of the neighbor graph associated with the system. Then we present a theoretical analysis for flocking, and show that the system achieves consensus at an exponential rate.

Scanning tunnelling microscope light emission: Finite temperature current noise and over cut-off emission.

Science.gov (United States)

Kalathingal, Vijith; Dawson, Paul; Mitra, J

2017-06-14

The spectral distribution of light emitted from a scanning tunnelling microscope junction not only bears its intrinsic plasmonic signature but is also imprinted with the characteristics of optical frequency fluc- tuations of the tunnel current. Experimental spectra from gold-gold tunnel junctions are presented that show a strong bias (V b ) dependence, curiously with emission at energies higher than the quantum cut-off (eV b ); a component that decays monotonically with increasing bias. The spectral evolution is explained by developing a theoretical model for the power spectral density of tunnel current fluctuations, incorporating finite temperature contribution through consideration of the quantum transport in the system. Notably, the observed decay of the over cut-off emission is found to be critically associated with, and well explained in terms of the variation in junction conductance with V b . The investigation highlights the scope of plasmon-mediated light emission as a unique probe of high frequency fluctuations in electronic systems that are fundamental to the electrical generation and control of plasmons.

The diffusivity of cesium, strontium, carbon and nickel in concrete and mixtures of sodium bentonite and crushed rock

International Nuclear Information System (INIS)

Muurinen, A.; Penttilae-Hiltunen, P.; Rantanen, J.

1986-07-01

The engineering barriers suggested to be used for the disposal of low and intermediate level wastes in Finland are concrete and crushed rock or mixtures of crushed rock and bentonite. In the repository the barriers are saturated by groundwater and radionuclides may be released by diffusion through the barries. For safety analysis, the mechanisms by which the nuclides migrate and corresponding parameters should be known. In this study diffusion measurements on different types of concrete and mixtures of sodium bentonite and crushed rock were carried out. Radioactive isotopes of cesium, strontium, carbon and nickel were used as tracers. The apparent diffusivities (Dsub(a)) were evaluated on the basis of the measurements. The apparent diffusivity of cesium in concretes was 10 -14 ...10 -15 m 2 /s. Strontium was mainly sorbed on cement where it diffuses slowly. Part of strontium propably penetrates in the rock ballast by diffusion. The diffusivities of carbon and nickel in the concrete was low. The upper limit was evaluated to be Dsub(a) -14 m 2 /s. The diffusivity of cesium in the mixtures of crushed rock and bentonite varies between 0.5x10 -12 and 7x10 -12 m 2 /s. Cesium was mainly sorbed on the rock. The diffusivity of strontium was 2x10 -11 ...2x10 -12 m 2 /s. Strontium was mainly sorbed on bentonite. The diffusion of the sorbed ions (surface diffusion) seems to be a additional migration mechanism in the case of cesium and strontium in the mixture of bentonite and crushed rock. The diffusivity of carbon in the mixtures of crushed rock and bentonite was 6x10 -11 ...4x10 -12 m 2 /s. No sorption was found in the case of carbon. The measured Dsub(a) of nickel in the mixtures of crushed rock and bentonite was 4x10 -14 ...2x10 -15 m 2 /s. The experimental arrangement was not, however, in the stationary state and the more correct values would propably be 10 -13 ...10 -14 m 2 /s. No surface diffusion was found in the case of nickel. (author)

Waist circumference cut-off values to predict the incidence of hypertension: an estimation from a Brazilian population-based cohort.

Science.gov (United States)

Gus, M; Cichelero, F Tremea; Moreira, C Medaglia; Escobar, G Fortes; Moreira, L Beltrami; Wiehe, M; Fuchs, S Costa; Fuchs, F Danni

2009-01-01

Central obesity is a key component in the definition of the metabolic syndrome, but the cut-off values proposed to define abnormal values vary among different guidelines and are mostly based on cross-sectional studies. In this study, we identify the best cut-off values for waist circumference (WC) associated with the incidence of hypertension. Participants for this prospectively planned cohort study were 589 individuals who were free of hypertension and selected at random from the community of Porto Alegre, Brazil. Hypertension was defined by a blood pressure measurement >or= 140/90 mmHg or the use of blood pressure lowering drugs. A logistic regression model established the association between WC and the incidence of hypertension. A receiver operating characteristics (ROC) curve analysis was used to select the best WC cut-off point to predict the incidence of hypertension. During a mean follow-up of 5.5+/-0.9 years, 127 subjects developed hypertension. The hazard ratios for the development of hypertension, adjusted for age, baseline systolic blood pressure, alcohol consumption, gender and scholarship were 1.02 (95% CI; 1.00-1.04; P=0.02) for WC. The best cut-off WC values to predict hypertension were 87 cm in men and 80 cm in women, with an area under the curve of 0.56 (95% CI; 0.47-0.64; P=0.17) and 0.70 (95% CI; 0.63-0.77; Phypertension in individuals living in communities in Brazil, and this risk begins at lower values of WC that those recommended by some guidelines.

Fourier phase analysis on equilibrium gated radionuclide ventriculography: range of phase spread and cut-off limits in normal individuals

International Nuclear Information System (INIS)

Ramaiah, Vijayaraghavan L.; Harish, B.; Sunil, H.V.; Selvakumar, Job; Ravi Kishore, A.G.; Nair, Gopinathan

2011-01-01

To define the range of phase spread on equilibrium gated radionuclide ventriculography (ERNV) in normal individuals and derive the cut-off limit for the parameters to detect cardiac dyssynchrony. ERNV was carried out in 30 individuals (age 53±23 years, 25 males and 5 females) who had no history of cardiovascular disease. They all had normal left ventricular ejection fraction (LVEF 55-70%) as determined by echocardiography, were in sinus rhythm, with normal QRS duration (≤120 msec) and normal coronary angiography. First harmonic phase analysis was performed on scintigraphic data acquired in best septal view. Left and right ventricular standard deviation (LVSD and RVSD, respectively) and interventricular mechanical delay (IVMD), the absolute difference of mean phase angles of right and left ventricle, were computed and expressed in milliseconds. Mean + 3 standard deviation (SD) was used to derive the cut-off limits. Average LVEF and duration of cardiac cycle in the study group were 62.5%±5.44% and 868.9±114.5 msec, respectively. The observations of LVSD, RVSD and right and left ventricular mean phase angles were shown to be normally distributed by Shapiro-Wilk test. Cut-off limits for LVSD, RVSD and IVMD were calculated to be 80 msec, 85 msec and 75 msec, respectively. Fourier phase analysis on ERNV is an effective tool for the evaluation of synchronicity of cardiac contraction. The cut-off limits of parameters of dyssynchrony can be used to separate heart failure patients with cardiac dyssynchrony from those without. ERNV can be used to select patients for cardiac resynchronization therapy. (author)

Design and simulation of thermal residual stresses of coatings on WC-Co cemented carbide cutting tool substrate

International Nuclear Information System (INIS)

Li, Anhai; Zhao, Jun; Zang, Jian; Zheng, Wei

2016-01-01

Large thermal residual stresses in coatings during the coating deposition process may easily lead to coating delamination of coated carbide tools in machining. In order to reduce the possibility of coating delamination during the tool failure process, a theoretical method was proposed and a numerical method was constructed for the coating design of WC-Co cemented carbide cutting tools. The thermal residual stresses of multi-layered coatings were analytically modeled based on equivalent parameters of coating properties, and the stress distribution of coatings are simulated by Finite element method (FEM). The theoretically calculated results and the FEM simulated results were verified and in good agreement with the experimental test results. The effects of coating thickness, tool substrate, coating type and interlayer were investigated by the proposed geometric and FEM model. Based on the evaluations of matchability of tool substrate and tool coatings, the basic principles of tool coating design were proposed. This provides theoretical basis for the selection and design of coatings of cutting tools in high-speed machining

Factors in selecting serum samples for use in determining the positive/negative threshold (cut-off) in ELISA

International Nuclear Information System (INIS)

Jacobson, R.H.

1998-01-01

The threshold (cut-off) that defines whether a test result is seropositive or seronegative is calculated by testing serum samples from a subpopulation of animals that is assumed to represent the target population in all aspects. For this proposition to be true, it is essential to consider the variables in the target population that must be represented in the subpopulation. Without representation of the variables in the subpopulation, it is likely that the cut-off selected for the test will be errant and will misclassify animals as to their infection status. The purpose of this paper is to identify a few of the principal variables that need to be taken into account when selecting a subpopulation of animals for test validation. (author)

Characterization of bentonite clay from Cubati, PB, Brazil

International Nuclear Information System (INIS)

Batista, A.P.; Marques, L.N.; Campos, L.A.; Neves, G.A.; Ferreira, H.C.; Menezes, R.R.

2009-01-01

The bentonite of the State of Paraiba are commercially used in numerous technological sectors, particularly in oil drilling muds. However, these bentonite deposits are becoming exhausted after decades of exploitation. Thus, the aim of this work was to characterize physically, mineralogically and technologically bentonite clays from Cubati city, PB. The samples were dried at 60 deg C and characterized through X-ray fluorescence, particle size distribution, X-ray diffraction, differential thermal and gravimetric analyzes and scanning electronic microscopy. The natural bentonite clays were transformed into sodium bentonite by Na_2CO_3 solution treatment. It was estimated the rheological properties of the suspensions: apparent and plastic viscosities and water loss. The results showed that the samples are polycationic bentonite clays, containing amounts of MgO, CaO and K_2O similar to those of bentonite from Boa Vista, PB, and are composed of smectite, kaolinite and quartz. The samples presented fractions of particles size under 2 μm of 30 and 32%. The rheological properties showed that the samples presented technological potential to be used in drilling muds. (author)

The warm dark matter halo mass function below the cut-off scale

Science.gov (United States)

Angulo, Raul E.; Hahn, Oliver; Abel, Tom

2013-10-01

Warm dark matter (WDM) cosmologies are a viable alternative to the cold dark matter (CDM) scenario. Unfortunately, an accurate scrutiny of the WDM predictions with N-body simulations has proven difficult due to numerical artefacts. Here, we report on cosmological simulations that, for the first time, are devoid of those problems, and thus are able to accurately resolve the WDM halo mass function well below the cut-off. We discover a complex picture, with perturbations at different evolutionary stages populating different ranges in the halo mass function. On the smallest mass scales we can resolve, identified objects are typically centres of filaments that are starting to collapse. On intermediate mass scales, objects typically correspond to fluctuations that have collapsed and are in the process of relaxation, whereas the high-mass end is dominated by objects similar to haloes identified in CDM simulations. We then explicitly show how the formation of low-mass haloes is suppressed, which translates into a strong cut-off in the halo mass function. This disfavours some analytic formulations that predict a halo mass function that would extend well below the free streaming mass. We argue for a more detailed exploration of the formation of the smallest structures expected to form in a given cosmology, which, we foresee, will advance our overall understanding of structure formation.

Development of an Improved Cement for Geothermal Wells

Energy Technology Data Exchange (ETDEWEB)

Trabits, George [Trabits Group, LLC, Wasilla, AK (United States)

2015-04-20

After an oil, gas, or geothermal production well has been drilled, the well must be stabilized with a casing (sections of steel pipe that are joined together) in order to prevent the walls of the well from collapsing. The gap between the casing and the walls of the well is filled with cement, which locks the casing into place. The casing and cementing of geothermal wells is complicated by the harsh conditions of high temperature, high pressure, and a chemical environment (brines with high concentrations of carbon dioxide and sulfuric acid) that degrades conventional Portland cement. During the 1990s and early 2000s, the U.S. Department of Energy’s Geothermal Technologies Office (GTO) provided support for the development of fly-ash-modified calcium aluminate phosphate (CaP) cement, which offers improved resistance to degradation compared with conventional cement. However, the use of CaP cements involves some operational constraints that can increase the cost and complexity of well cementing. In some cases, CaP cements are incompatible with chemical additives that are commonly used to adjust cement setting time. Care must also be taken to ensure that CaP cements do not become contaminated with leftover conventional cement in pumping equipment used in conventional well cementing. With assistance from GTO, Trabits Group, LLC has developed a zeolite-containing cement that performs well in harsh geothermal conditions (thermal stability at temperatures of up to 300°C and resistance to carbonation) and is easy to use (can be easily adjusted with additives and eliminates the need to “sterilize” pumping equipment as with CaP cements). This combination of properties reduces the complexity/cost of well cementing, which will help enable the widespread development of geothermal energy in the United States.

Quality control and characterization of bentonite materials

International Nuclear Information System (INIS)

Kiviranta, L.; Kumpulainen, S.

2011-12-01

Before bentonite material is taken into use in performance testing, the quality of the material needs to be checked. Three high grade bentonite materials: two natural Nabentonites from Wyoming, and one natural Ca-bentonite from Milos, were characterized. Each material was characterized using duplicate or triplicate samples in order to study variability in material quality in batches. The procedure consisted of basic acceptance testing (water ratio, CEC, swelling index, liquid limit, and granule size distribution), advanced acceptance testing (exchangeable cations, chemical and mineralogical composition, density, swelling pressure and hydraulic conductivity) and complementary testing (herein surface area, water absorption capacity, montmorillonite composition, grain size distribution and plastic limit). All three materials qualified the requirements set for buffer bentonite for CEC, smectite content, swelling pressure, and hydraulic conductivity. Wyoming bentonites contained approximately 88 wt.% of smectite, and Milos bentonite 79 wt.% of smectite and 3 wt.% of illite. Precision of smectite analyses was ±2 %, and variances in composition of parallel samples within analytical errors, at least for Wyoming bentonites. Accuracy of quantitative analyses for trace minerals such as gypsum, pyrite or carbonates, was however low. As the concentrations of these trace minerals are important for Eh or pH buffering reactions or development of bentonite pore water composition, normative concentrations are recommended to be used instead of mineralogically determined concentrations. The swelling pressures and hydraulic conductivities of different materials were compared using EMDD. Swelling pressure was relatively higher for studied Cabentonite than for the studied Na-bentonites and the difference could not be explained with different smectite contents. Hydraulic conductivities seemed to be similar for all materials. The results of index tests correlated with the smectite content

Bentonite-amended soil special study

International Nuclear Information System (INIS)

1989-12-01

This special study was conducted to assess the viability of soil with a high percentage of bentonite added as an infiltration barrier in the cover of Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cells. To achieve maximum concentration limits (MCLs) at several UMTRA Project sites, covers with a very low permeability are needed. If alternate concentration limits (ACLs) are the appropriate site groundwater compliance strategy, the US Department of Energy (DOE) is required to demonstrate, among other things, that the infiltration to the disposal cell is as low as reasonably achievable, and hence that the cover has a very low permeability. When the study discussed here was begun, the lowest permeability element available was CLAYMAX R , a manufactured liner material constructed of natural material (bentonite clay) between two geosynthetics.The strength of soil-bentonite mixes was measured to see if they could be placed on sideslopes and not pose stability problems. Also evaluated were the hydraulic conductivities of soil-bentonite mixes. If the strengths and permeabilities of soils with a high percentage of bentonite are favorable, the soils may be used as infiltration barriers in current cover designs without changing pile geometries. The scope of work for this study called for a literature review and a two-phased laboratory testing program. This report presents the results of the literature review and the first phase of the testing program

Bentonite. Geotechnical barrier and source for microbial life

International Nuclear Information System (INIS)

Matschiavelli, Nicole; Kluge, Sindy; Cherkouk, Andrea; Steglich, Jennifer

2017-01-01

Due to their properties, namely a high swelling capacity and a low hydraulic conductivity, Bentonites fulfil as geotechnical barrier a sealing and buffering function in the nuclear waste repository. Depending on the mineral composition Bentonites contain many suitable electron-donors and -acceptors, enabling potential microbial life. For the potential repository of highly radioactive waste the microbial mediated transformation of Bentonite could influence its properties as a barrier material. Microcosms were set up containing Bentonite and anaerobic synthetic Opalinus-clay-pore water solution under an N_2/CO_2-atmosphere to elucidate the microbial potential within selected Bentonites. Substrates like acetate and lactate were supplemented to stimulate potential microbial activity. First results show that bentonites represent a source for microbial life, demonstrated by the consumption of lactate and the formation of pyruvate. Furthermore, microbial iron-reduction was determined, which plays a crucial role in Betonite-transformation.

Bentonite. Geotechnical barrier and source for microbial life

Energy Technology Data Exchange (ETDEWEB)

Matschiavelli, Nicole; Kluge, Sindy; Cherkouk, Andrea [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). HZDR Young Investigator Group; Steglich, Jennifer

2017-06-01

Due to their properties, namely a high swelling capacity and a low hydraulic conductivity, Bentonites fulfil as geotechnical barrier a sealing and buffering function in the nuclear waste repository. Depending on the mineral composition Bentonites contain many suitable electron-donors and -acceptors, enabling potential microbial life. For the potential repository of highly radioactive waste the microbial mediated transformation of Bentonite could influence its properties as a barrier material. Microcosms were set up containing Bentonite and anaerobic synthetic Opalinus-clay-pore water solution under an N{sub 2}/CO{sub 2}-atmosphere to elucidate the microbial potential within selected Bentonites. Substrates like acetate and lactate were supplemented to stimulate potential microbial activity. First results show that bentonites represent a source for microbial life, demonstrated by the consumption of lactate and the formation of pyruvate. Furthermore, microbial iron-reduction was determined, which plays a crucial role in Betonite-transformation.

Exchangeability of bentonite buffer and backfill materials

Energy Technology Data Exchange (ETDEWEB)

Savage, D. [Savage Earth Associates Ltd, Bournemouth (United Kingdom); Arthur, R. [Intera Inc, Ottawa, ON, (Canada); Luukkonen, A.

2012-08-15

Clay-based buffer and tunnel backfill materials are important barriers in the KBS-3 repository concept for final disposal of spent nuclear fuel in Finland. One issue that is relevant to material properties is the degree to which different bentonite compositions can be regarded as interchangeable. In Posiva's current repository design, the reference bentonite composition is MX-80, a sodium montmorillonite dominated clay. Posiva would like to be able to use bentonite with Ca-montmorillonite as the dominant clay mineral. However, at this stage, it is not clear what supporting data need to be acquired/defined to be able to place the state of knowledge of Ca-bentonite at the same level as that of Na-bentonite. In this report, the concept of bentonite exchangeability has been evaluated through consideration of how bentonite behaviour may be affected in six key performance-relevant properties, namely (1) mineralogical composition and availability of materials, (2) hydraulic conductivity, (3) mechanical and rheological properties, (4) long-term alteration, (5) colloidal properties, and (6) swelling pressure. The report evaluates implications for both buffer and backfill. Summary conclusions are drawn from these sections to suggest how bentonite exchangeability may be addressed in regulatory assessments of engineered barrier design for a future geological repository for spent fuel in Finland. Some important conclusions are: (a) There are some fundamental differences between Ca- and Na-bentonites such as colloidal behaviour, pore structure and long-term alteration that could affect the exchangeability of these materials as buffer or backfill materials and which should be further evaluated; (b) Additional experimental data are desirable for some issues such as long-term alteration, hydraulic properties and swelling behaviour, (c) The minor mineral content of bentonites is very variable, both between different bentonites and within the same bentonite type, it is not clear

Chemical interaction of fresh and saline waters with compacted bentonite

International Nuclear Information System (INIS)

Muurinen, A.; Lehikoinen, J.; Melamed, A.; Pitkaenen, P.

1996-01-01

The interaction of compacted sodium bentonite with fresh and saline ground-water simulant was studied. The parameters varied in the experiments were the compositions of the solutions and oxygen and carbon dioxide content in the surroundings. The main interests of the study were the chemical changes in the experimental solution, bentonite porewater and bentonite together with the microstructural properties of bentonite. The major processes with fresh water were the diffusion of sodium, potassium, sulphate, bicarbonate and chloride from bentonite to the solution, and the diffusion of calcium and magnesium from the solution into bentonite. The major processes in the experiments with saline water were the diffusion of the sodium, magnesium, sulphate and bicarbonate from bentonite into the solution, and the diffusion of calcium from the solution into bentonite

Bentonite erosion by dilute waters in initially saturated bentonite

International Nuclear Information System (INIS)

Olin, Markus; Seppaelae, Anniina; Laurila, Teemu; Koskinen, Kari

2012-01-01

Document available in extended abstract form only. One scenario of interest for the long-term safety assessment of a spent nuclear fuel repository involves the loss of bentonite buffer material through contact with dilute groundwater at a transmissive fracture interface (SKB 2011, Posiva 2012a). The scenario is based on the stable colloids at low ionic strength: - the cohesive forces of bentonite decrease in low-salinity conditions, and colloids start to dominate and are able to leave the gel-like bentonite on the groundwater bentonite boundary; - after colloid formation, groundwater may carry away the only just released clay colloids; - low-salinity events are most probable during post-glacial conditions, when also pressure gradients are high, causing elevated flow velocity, which may enhance colloidal transport. Therefore, it is very important from the point of view of repository safety assessment to be able to estimate how much bentonite may be lost during a post-glacial event, when the groundwater salinity and velocity, as well as the duration of the event are fixed. It is possible that more than one event will hit the same canister and buffer, and that several canisters and buffers may be jeopardized. The results in the issue so far may be divided into modelling attempts and experimental work. The modelling has been based on two main guidelines: external (Birgersson et al., 2009) and internal friction models (Neretnieks et al., 2009). However, these models have not been validated for erosion, probably due to lack of suitable laboratory data. The latter approach is more ambitious due to lack of fitting parameters, though the internal friction model itself may be varied. The internal friction model has proven to be time-consuming to solve numerically. This work indicates that experiments carried out by Schatz et al. (2012) differ significantly from the predictions obtained from Neretnieks' model. We present our numerical modelling results based on a set of

Bubble jet impact on a rigid wall of different stand-off parameters

International Nuclear Information System (INIS)

Li, S; Wang, S P; Zhang, A M

2015-01-01

One of the key features of the dynamics of a bubble near a rigid wall is the development of a high liquid jet, generating highly localized pressure on the wall. In present study, the boundary integral method is employed to simulate this phenomenon, and the vortex ring model is introduced to handle the discontinued potential of the toroidal bubble. Meanwhile, the pressure induced in the whole process is calculated by an auxiliary function. The effect of the stand-off parameter on the bubble dynamics and the pressure on the wall is investigated, and a double-peaked structure occurs in the pressure profile after the jet impact in some cases, which is associated with the jet impact and the high internal pressure inside the bubble

Verification arrangements for the proposed fissile material cut-off treaty

International Nuclear Information System (INIS)

Bragin, V.

2001-01-01

Since the mid-1950's, an agreement to terminate the production of fissile material for nuclear weapons has been on the agenda. On December 16, 1993, the UNGA adopted Resolution A/RES/48/75/L which recommends ''the negotiation in the most appropriate international forum of a non-discriminatory, multilateral and internationally and effectively verifiable treaty banning the production of fissile material for nuclear weapons and other nuclear explosive devices''. The proposed Fissile Material Cut-off Treaty (FMCT) is still one of the most important items on the multilateral disarmament and non-proliferation agenda. Successful achievement of the FMCT would be an important step towards the goal of eliminating nuclear weapons. (author)

Impact of corrosion-derived iron on the bentonite buffer within the KBS-3H disposal concept. The Olkiluoto site as case study

International Nuclear Information System (INIS)

Wersin, Paul; Birgersson, Martin; Olsson, Siv; Karnland, Ola; Snellman, Margit

2008-05-01

Steel components are unstable in EBS environments. They will corrode to fairly insoluble corrosion products, such as magnetite, and also react with the smectitic matrix of the bentonite buffer. In this study, the impact of reduced iron on the buffer's stability has been assessed within the framework of the KBS-H concept. Our work includes two parts. In the first part, available data from experimental and modelling studies have been compiled and interpreted. In the second part, a relatively simple geochemical modelling exercise on the iron-bentonite interaction in the current KBS-3H disposal system has been performed using Olkiluoto as test case. The iron in this case stems from the perforated supercontainer steel shell foreseen to be emplaced around the buffer material. The iron-bentonite interaction under reducing conditions may involve different processes including sorption, redox and dissolution/precipitation reactions, the details of which are not yet understood. One process to consider is the sorption of corrosion-derived Fe(II). This process is fast and leads to strong binding of Fe(II) at the smectite surface. Whether this sorption reaction is accompanied by a redox and surface precipitation reaction is presently not clear. A further process to consider under very reducing conditions is the reduction of structural Fe(III) in the clay which may destabilise the montmorillonite structure. The process of greatest relevance for the buffer's performance is montmorillonite transformation in contact with reduced iron. This process is very slow and experimentally difficult to investigate. Current data suggest that the transformation process may either lead to a Fe-rich smectite (e.g. saponite) or to a non-swelling clay (berthierine or chlorite). In addition, cementation due to precipitation of iron corrosion products or of SiO 2 resulting from montmorillonite transformation may occur. Physical properties of the buffer may in principle be affected by montmorillonite

Impact of corrosion-derived iron on the bentonite buffer within the KBS-3H disposal concept. The Olkiluoto site as case study

Energy Technology Data Exchange (ETDEWEB)

Wersin, Paul (National Cooperative for the Disposal of Radioactive Waste, Nagra, Wettingen (Switzerland)); Birgersson, Martin; Olsson, Siv; Karnland, Ola (Clay Technology AB, Lund (Sweden)); Snellman, Margit (Saanio and Riekkola Oy, Helsinki (Finland))

2008-05-15

Steel components are unstable in EBS environments. They will corrode to fairly insoluble corrosion products, such as magnetite, and also react with the smectitic matrix of the bentonite buffer. In this study, the impact of reduced iron on the buffer's stability has been assessed within the framework of the KBS-H concept. Our work includes two parts. In the first part, available data from experimental and modelling studies have been compiled and interpreted. In the second part, a relatively simple geochemical modelling exercise on the iron-bentonite interaction in the current KBS-3H disposal system has been performed using Olkiluoto as test case. The iron in this case stems from the perforated supercontainer steel shell foreseen to be emplaced around the buffer material. The iron-bentonite interaction under reducing conditions may involve different processes including sorption, redox and dissolution/precipitation reactions, the details of which are not yet understood. One process to consider is the sorption of corrosion-derived Fe(II). This process is fast and leads to strong binding of Fe(II) at the smectite surface. Whether this sorption reaction is accompanied by a redox and surface precipitation reaction is presently not clear. A further process to consider under very reducing conditions is the reduction of structural Fe(III) in the clay which may destabilise the montmorillonite structure. The process of greatest relevance for the buffer's performance is montmorillonite transformation in contact with reduced iron. This process is very slow and experimentally difficult to investigate. Current data suggest that the transformation process may either lead to a Fe-rich smectite (e.g. saponite) or to a non-swelling clay (berthierine or chlorite). In addition, cementation due to precipitation of iron corrosion products or of SiO{sub 2} resulting from montmorillonite transformation may occur. Physical properties of the buffer may in principle be affected by

Sorption of strontium on bentonites from Slovak deposits

International Nuclear Information System (INIS)

Kufcakova, J.; Galambos, M.; Rajc, P.

2005-01-01

Sorption on bentonite from different Slovak deposits / Jelsovy potok, Kopernica and Lieskove has been investigated under various experimental conditions, such as contact time, pH, sorbate concentrations, presence of complementary cation. The sorption of strontium from aqueous solutions was investigated using a radiometric determination of distribution coefficient, Kd. The individual solutions were labelled with radiotracer. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites /tab.l/ , which can be explained by the increase of specific surface and change of solubility of the irradiated samples of bentonite. The presence of complementary cations, Na + , K + , NH 4 + , Ca 2+ , Mg 2+ and Ba 2+ depresses the sorption of Sr on bentonite. In the case of bentonite Kopernica the effectiveness in reducing the sorption of strontium by cations followed the order K + 4 + + 2+ 2+ 2+ . Results indicate that the sorption of Sr + on bentonite will be affected by the presence of high concentrations of various salts in the waste water effluents. (author)

40 CFR 761.60 - Disposal requirements.

Science.gov (United States)

2010-07-01

... hardening slurry consisting of cement, bentonite, or clay) or high density polyurethane foam. (B) PCB... hardening slurry-like cement, bentonite, or clay) or high density polyurethane foam (except that only cement...

Transport of wall released impurities in the limiter scrape-off layer of a tokamak

International Nuclear Information System (INIS)

Claassen, H.A.; Repp, H.

1978-01-01

A collisional theory for the transport of heavy wall released impurities in the plasma scrape-off layer is developed, which to zero order approximation considers electron impact ionization and Coulomb collisions with the plasma ions. Impurity ion convection parallel to the magnetic field and radial drift motion are treated as first order correction terms. The theory, which under certain restrictions to the integral coefficients of the Fokker-Planck collision operator is independent of the special form of the plasma ion distribution, is applied to the calculation of the impurity ion fluxes in the scrape-off layer. Preliminary numerical results are presented for a model plasma ion distribution of the loss ellipse type and a half-maxwellian distribution of the wall released impurity atoms. (Auth.)

Methods for identifying the cost effective case definition cut-off for sequential monitoring tests: an extension of Phelps and Mushlin

Science.gov (United States)

Longo, Roberta; Baxter, Paul; Hall, Peter; Hewison, Jenny; Afshar, Mehran; Hall, Geoff; McCabe, Christopher

2015-01-01

The arrival of personalized medicine in the clinic means that treatment decisions will increasingly rely on test results. The challenge of limited health care resources means that the dissemination of these technologies will be dependent on their value in relation to their cost; i.e. their cost effectiveness. Phelps and Mushlin have described how to optimize tests to meet cost effectiveness target. However, when tests are applied repeatedly the case mix of the patients tested changes with each administration, and this impacts upon the value of each subsequent test administration. In this paper we present a modification of Phelps and Mushlin’s framework for diagnostic tests; to identify the cost effective cut-off for monitoring tests. Using the Ca125 test monitoring for relapse in Ovarian Cancer, we show how the repeated use of the initial cut-off can lead to a substantially increased false negative rate compared to the monitoring cut-off – over 20% higher than in this example – with the associated harms for individual and population health. PMID:24488576

Optimal cut-off levels to define obesity: body mass index and waist circumference, and their relationship to cardiovascular disease, dyslipidaemia, hypertension and diabetes in Malaysia.

Science.gov (United States)

Zaher, Zaki Morad Mohd; Zambari, Robayaah; Pheng, Chan Siew; Muruga, Vadivale; Ng, Bernard; Appannah, Geeta; Onn, Lim Teck

2009-01-01

Many studies in Asia have demonstrated that Asian populations may require lower cut-off levels for body mass index (BMI) and waist circumference to define obesity and abdominal obesity respectively, compared to western populations. Optimal cut-off levels for body mass index and waist circumference were determined to assess the relationship between the two anthropometric- and cardiovascular indices. Receiver operating characteristics analysis was used to determine the optimal cut-off levels. The study sample included 1833 subjects (mean age of 44+/-14 years) from 93 primary care clinics in Malaysia. Eight hundred and seventy two of the subjects were men and 960 were women. The optimal body mass index cut-off values predicting dyslipidaemia, hypertension, diabetes mellitus, or at least one cardiovascular risk factor varied from 23.5 to 25.5 kg/m2 in men and 24.9 to 27.4 kg/m2 in women. As for waist circumference, the optimal cut-off values varied from 83 to 92 cm in men and from 83 to 88 cm in women. The optimal cut-off values from our study showed that body mass index of 23.5 kg/m2 in men and 24.9 kg/m2 in women and waist circumference of 83 cm in men and women may be more suitable for defining the criteria for overweight or obesity among adults in Malaysia. Waist circumference may be a better indicator for the prediction of obesity-related cardiovascular risk factors in men and women compared to BMI. Further investigation using a bigger sample size in Asia needs to be done to confirm our findings.

Comparison of interferon-γ release assay to two cut-off points of tuberculin skin test to detect latent Mycobacterium tuberculosis infection in primary health care workers.

Directory of Open Access Journals (Sweden)

Fernanda Mattos de Souza

Full Text Available An interferon-γ release assay, QuantiFERON-TB (QFT test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI. Here, we compared the performance of QFT with tuberculin skin test (TST measured at two different cut-off points among primary health care work (HCW in Brazil.A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points.We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31, and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22. We investigated possible factors of discordance of TST vs QFT. Compared to the TST-/QFT- group, risk factors for discordance in the TST+/QFT- group with TST cut-off of ≥5 mm included age between 41-45 years [OR = 2.70; CI 95%: 1.32-5.51] and 46-64 years [OR = 2.04; CI 95%: 1.05-3.93], BCG scar [OR = 2.72; CI 95%: 1.40-5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09-4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03-4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01-2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05-2.62], were significantly associated with the TST+/QFT- group. No statistically significant associations were found among the TST-/QFT+ discordant group with either TST cut-off value.Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed.

Comparison of interferon-γ release assay to two cut-off points of tuberculin skin test to detect latent Mycobacterium tuberculosis infection in primary health care workers.

Science.gov (United States)

de Souza, Fernanda Mattos; do Prado, Thiago Nascimento; Pinheiro, Jair dos Santos; Peres, Renata Lyrio; Lacerda, Thamy Carvalho; Loureiro, Rafaela Borge; Carvalho, Jose Américo; Fregona, Geisa; Dias, Elias Santos; Cosme, Lorrayne Beliqui; Rodrigues, Rodrigo Ribeiro; Riley, Lee Wood; Maciel, Ethel Leonor Noia

2014-01-01

An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST-/QFT- group, risk factors for discordance in the TST+/QFT- group with TST cut-off of ≥5 mm included age between 41-45 years [OR = 2.70; CI 95%: 1.32-5.51] and 46-64 years [OR = 2.04; CI 95%: 1.05-3.93], BCG scar [OR = 2.72; CI 95%: 1.40-5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09-4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03-4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01-2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05-2.62], were significantly associated with the TST+/QFT- group. No statistically significant associations were found among the TST-/QFT+ discordant group with either TST cut-off value. Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed.

Application of new mycotoxin adsorbent-bentonite clay “Askangel” in poultry feed

OpenAIRE

A. Chkuaseli; M. Khutsishvili-Maisuradze; A. Chagelishvili; K. Natsvaladze; T. Lashkarashvili; G. Chagelishvili; N. Maisuradze

2016-01-01

In order to mitigate the negative effect of mycotoxins the major researches have been conducted to obtain the mycotoxins adsorbent in recent years. As for the adsorbents, they are substances of a firm or liquid form, on which surface the mycotoxins are absorbed and prevent transition of mycotoxins from the intestines walls in to blood system. The bentonite clay obtained in western region of Georgia (Guria, Ozurgeti) is characterized with a broad range of ion exchange, high colloidal, enriched...

Evaluation of an Optimal Cut-Off Point for the Ki-67 Index as a Prognostic Factor in Primary Breast Cancer: A Retrospective Study.

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Rumiko Tashima

Full Text Available The Ki-67 index is an important biomarker for indicating the proliferation of cancer cells and is considered to be an effective prognostic factor for breast cancer. However, a standard cut-off point for the Ki-67 index has not yet been established. Therefore, the aim of this retrospective study was to determine an optimal cut-off point in order to establish it as a more accurate prognostic factor. Immunohistochemical analysis of the Ki-67 index was performed on 4329 patients with primary breast cancer from August 1987 to March 2012. Out of this sample, there were 3186 consecutive cases from September 1997 with simultaneous evaluations of ER, PgR and HER2 status. Cox's proportional hazard model was used to perform univariate and multivariate analyses of the factors related to OS. The hazard ratios (HR and the p values were then compared to determine the optimal cut-off point for the Ki-67 index. The median Ki-67 index value was 20.5% (mean value 26.2%. The univariate analysis revealed that there was a statistically significant negative correlation with DFS and OS and the multivariate analysis revealed that the Ki-67 index value was a significant factor for DFS and OS. The top seven cut-off points were then carefully chosen based on the results of the univariate analysis using the lowest p-values and the highest HR as the main selection criteria. The multivariate analysis of the factors for OS showed that the cut-off point of 20% had the highest HR in all of the cases. However, the cutoff point of 20% was only a significant factor for OS in the Luminal/HER2- subtype. There was no correlation between the Ki-67 index value and OS in any of the other subtypes. These data indicate that the optimal cut-off point of 20% is the most effective prognostic factor for Luminal/HER2- breast cancer.

Accurate cut-offs for predicting endoscopic activity and mucosal healing in Crohn's disease with fecal calprotectin

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Juan María Vázquez-Morón

Full Text Available Background: Fecal biomarkers, especially fecal calprotectin, are useful for predicting endoscopic activity in Crohn's disease; however, the cut-off point remains unclear. The aim of this paper was to analyze whether faecal calprotectin and M2 pyruvate kinase are good tools for generating highly accurate scores for the prediction of the state of endoscopic activity and mucosal healing. Methods: The simple endoscopic score for Crohn's disease and the Crohn's disease activity index was calculated for 71 patients diagnosed with Crohn's. Fecal calprotectin and M2-PK were measured by the enzyme-linked immunosorbent assay test. Results: A fecal calprotectin cut-off concentration of ≥ 170 µg/g (sensitivity 77.6%, specificity 95.5% and likelihood ratio +17.06 predicts a high probability of endoscopic activity, and a fecal calprotectin cut-off of ≤ 71 µg/g (sensitivity 95.9%, specificity 52.3% and likelihood ratio -0.08 predicts a high probability of mucosal healing. Three clinical groups were identified according to the data obtained: endoscopic activity (calprotectin ≥ 170, mucosal healing (calprotectin ≤ 71 and uncertainty (71 > calprotectin < 170, with significant differences in endoscopic values (F = 26.407, p < 0.01. Clinical activity or remission modified the probabilities of presenting endoscopic activity (100% vs 89% or mucosal healing (75% vs 87% in the diagnostic scores generated. M2-PK was insufficiently accurate to determine scores. Conclusions: The highly accurate scores for fecal calprotectin provide a useful tool for interpreting the probabilities of presenting endoscopic activity or mucosal healing, and are valuable in the specific clinical context.

Shrinkage deformation of cement foam concrete

Science.gov (United States)

Kudyakov, A. I.; Steshenko, A. B.

2015-01-01

The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

Diffusion of uranium in compacted sodium bentonite

International Nuclear Information System (INIS)

Muurinen, A.; Lehikoinen, J.

1992-09-01

In the study the diffusion of uranium dissolved from uranium oxide fuel was studied experimentally in compacted sodium bentonite (Wyoming bentonite MX-80). The experiments were carried out by the through-diffusion method. The parameters varied in the study were the density of bentonite, salt content of the solution and redox conditions. Uranium was dissolved under aerobic conditions in order to simulate oxic conditions possibly caused by radiolysis in the repository

Filtration behavior of organic substance through a compacted bentonite

International Nuclear Information System (INIS)

Kanaji, Mariko; Kuno, Yoshio; Yui, Mikazu

1999-07-01

Filtration behavior of organic substance through a compacted bentonite was investigated. Na-type bentonite containing 30wt% of quartz sand was compacted in a column and the dry density was adjusted to be 1.6 g/cm 3 . Polyacrylic acid solution (including three types of polyacrylic acid, average molecular weight 2,100, 15,000 and 450,000) was prepared and was passed through the compacted bentonite. Molecular weight distributions of polyacrylic acid in the effluent solution were analysed by GPC (Gel Permeation Chromatography). A batch type experiment was also carried out in order to examine a sorption behavior of these organic substances onto the surfaces of grains of the bentonite. The results indicated that the smaller size polyacrylic acid (molecular weight < 100,000) was passed through the compacted bentonite. On the other hand, the larger size polyacrylic acid (molecular weight ≥100,000) was mostly filtrated by the compacted bentonite. The batch type sorption tests clarified that the polyacrylic acid did not sorb onto the surfaces of minerals constituting the bentonite. Therefore it was suggested that the larger size molecules (≥100,000) of organic substances could be predominantly filtrated by the microstructure of the compacted bentonite. (author)

Cut-off value of FEV1/FEV6 as a surrogate for FEV1/FVC for detecting airway obstruction in a Korean population

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Chung KS

2016-08-01

Full Text Available Kyung Soo Chung,1,2 Ji Ye Jung,1,2 Moo Suk Park,1,2 Young Sam Kim,1,2 Se Kyu Kim,1,2 Joon Chang,1,2 Joo Han Song1,2 1Division of Pulmonology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea; 2Institute of Chest Disease, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea Background: Forced expiratory volume in 1 second (FEV1/forced expiratory volume in 6 seconds (FEV6 has been proposed as an alternative to FEV1/forced vital capacity (FVC for detecting airway obstruction. A fixed cut-off value for FEV1/FEV6 in a Korean population is lacking. We investigated a fixed cut-off for FEV1/FEV6 as a surrogate for FEV1/FVC for detecting airway obstruction.Materials and methods: We used data obtained in the 5 years of the Fifth and Sixth Korean National Health and Nutrition Examination Survey. A total of 14,978 participants aged ≥40 years who underwent spirometry adequately were the study cohort. “Airway obstruction” was a fixed cut-off FEV1/FVC <70% according to the Global Initiative for Chronic Obstructive Lung Disease guidelines. We also used European Respiratory Society/Global Lung Initiative 2012 equations for the FEV1/FVC lower limit of normal.Results: Among the 14,978 participants (43.5% male, 56.5% female; mean age: 56.9 years for men and 57.0 years for women, 14.0% had obstructive lung function according to a fixed cut-off FEV1/FVC <70%. Optimal FEV1/FEV6 cut-off for predicting FEV1/FVC <70% was 75% using receiver operating characteristic curve analyses (area under receiver operating characteristic curve =0.989, 95% confidence interval 0.987–0.990. This fixed cut-off of FEV1/FEV6 showed 93.8% sensitivity, 94.8% specificity, 74.7% positive predictive value, 98.9% negative predictive value, and 0.8 Cohen’s kappa coefficient. When compared with FEV1/FVC < lower limit of normal, FEV1/FEV6 <75% tended to over-diagnose airflow limitation (just like a fixed cut-off

Enhanced shear strength of sodium bentonite using frictional additives

International Nuclear Information System (INIS)

Schmitt, K.E.; Bowders, J.J.; Gilbert, R.B.; Daniel, D.E.

1997-01-01

One of the most important obstacles to using geosynthetic clay liners (GCLs) in landfill cover systems is the low shear strength provided by the bentonitic portion of the GCL. In this study, the authors propose that granular, frictional materials might be added to the bentonite to form an admixture that would have greater shear strength than the bentonite alone while still raining low hydraulic conductivity. Bentonite was mixed with two separate granular additives, expanded shale and recycled to form mixtures consisting of 20-70% bentonite by weight. In direct shear tests at normal stresses of 34.5-103.5 kPa, effective friction angles were measured as 45 degrees for the expanded 36 degrees for the recycled glass, and 7 degrees for the hydrated granular bentonite. The strength of the expanded shale mixtures increased nearly linearly as the percentage shale in the mixture increased, to 44 degrees for a bentonite mixture with 80% shale. The addition of recycled glass showed little effect on the shear strength of the mixtures of glass and bentonite. Hydraulic conductivity measurements for both types of mixtures indicated a linear increase with log(k) as the amount of granular additive increased. For applications involving geosynthetic clay liners for cover systems, a mixture of 40% expanded shale and 60% bentonite is recommended, although further testing must be done. The 40/60 mixture satisfies the hydraulic equivalency requirement, with k = 5.1X10 -9 cm/sec, while increasing the shear strength parameters of the bentonitic mixture to φ' = 17 degrees and c' = 0

A comparison of nano bentonite and some nano chemical additives to improve drilling fluid using local clay and commercial bentonites

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Nada S. Al-Zubaidi

2017-09-01

In the second part, a commercial bentonite was used and mixed with nano commercial bentonite and nano chemical materials (MgO, TiO2, and graphene at 0.005, 0.01, 0.05, 0.1, 0.2 and 0.4 wt% concentrations. The results showed that nano commercial bentonite gives the same filtration behavior of graphene, whereas, the plastic viscosity, yield point and apparent viscosity were the same when using nano commercial bentonite, TiO2 and graphene. The best results were obtained with MgO addition, whereby the filter loss decreased to 35% with a higher value of yield point.

Influence of selected factors on strontium sorption on bentonites

International Nuclear Information System (INIS)

Galambos, M.; Kufcakova, J.; Rajec, P.

2007-01-01

Sorption on bentonite will play an important role in retarding the migration of radionuclides from a waste repository. Bentonite is a natural clay and one of the most promising candidates for use as a buffer material in the geological disposal systems for high-level nuclear waste. It is intended to isolate metal canisters with highly radioactive waste products from the surrounding rocks because of its ability to retard the movement of radionuclides by sorption. Bentonite is characterized by low permeability, water swelling capability and excellent sorption potential for cationic radionuclides. To correctly assess the sorption potential of radionuclides on bentonite is essential for the development of predictive migration models. The sorption of strontium on bentonite from different Slovak deposits - Jelsovy potok, Kopernica and Lieskovec has been investigated under various experimental conditions, such as contact time, sorbate concentrations, presence of complementary cation. Sorption was studied using the batch technique. The uptake of Sr was rapid and equilibrium was reached almost instantaneously. The instantaneous uptake may be due to adsorption and/or exchange of the metal with some ions on the surface of the adsorbent. The best sorption characteristics distinguish bentonite Kopernica, sorption capacity for Sr of the fraction under 45 mm is 0,48 mmol·g -1 for Sr. The highest values of distribution coefficient were reached for the bentonite Jelsovy potok. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites, which can be explained by the increase of specific surface of the bentonite samples. The presence of complementary cations depresses the sorption of Sr on bentonite. Cations Ca 2+ exhibit higher effect on cesium sorption than the Na 2+ ions. Results indicate that the sorption of Sr 2+ on bentonite will be affected by the presence of high concentrations of various salts in the waste water

STUDY OF THERMAL AND ACID STABILITY OF BENTONITE CLAY

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Karna Wijaya

2010-06-01

Full Text Available The thermal and acid stability of the bentonite clays (Na- and Ca-bentonite have been tested. The thermal stability testing has been carried out by heating 5 gram of the clays  for five hours at 200, 300 and 500 °C respectively, meanwhile acid stability testing was performed by immersing 5 gram clays into 100 mL sulphuric acid 1M, 2M and 3M for 24 hours. The tested clays, then were characterized by means of X-Ray difractometry and IR-spectroscopy methods. The characterization results showed that upon heating, both Ca- and Na-bentonites indicated same thermal stability. However, upon acid treatment, Na-bentonite was found relatively stabiler and more resistance then Ca-bentonite.   Keywords: bentonite, clay, thermal stability, acid stability.

Removal of nitrate by zero-valent iron and pillared bentonite

International Nuclear Information System (INIS)

Li Jianfa; Li Yimin; Meng Qingling

2010-01-01

The pillared bentonite prepared by intercalating poly(hydroxo Al(III)) cations into bentonite interlayers was used together with Fe(0) for removing nitrate in column experiments. The obvious synergetic effect on nitrate removal was exhibited through uniformly mixing the pillared bentonite with Fe(0). In such a mixing manner, the nitrate was 100% removed, and the removal efficiency was much higher than the simple summation of adsorption by the pillared bentonite and reduction by Fe(0). The influencing factors such as bentonite type, amount of the pillared bentonite and initial pH of nitrate solutions were investigated. In this uniform mixture, the pillared bentonite could adsorb nitrate ions, and facilitated the mass transfer of nitrate onto Fe(0) surface, then accelerated the nitrate reduction. The pillared bentonite could also act as the proton-donor, and helped to keep the complete nitrate removal for at least 10 h even when the nitrate solution was fed at nearly neutral pH.

Diagnostic Cut-Off Levels of Plasma Brain Natriuretic Peptide to Distinguish Left Ventricular Failure in Emergency Setting

International Nuclear Information System (INIS)

Hussain, A.; Afridi, F. I.; Lutfi, I. A.

2014-01-01

Objective: To determine the diagnostic cut-off values of brain natriuretic (BNP) peptide to establish left ventricular failure in patients presenting with dyspnoea in emergency department. Study Design: Descriptive study. Place and Duration of Study: Ziauddin University Hospital, Karachi, from July to December 2011. Methodology: BNP estimation was done on Axysm analyzer with kit provided by Abbott diagnostics, while the Doppler echocardiography was done on Toshiba style (UICW-660A) using 2.5 MHz and 5.0 MHz probes. Log transformation was done to normalize the original BNP values. A receiver operating curve was plotted to determine the diagnostic cut-off value of BNP which can be used to distinguish CHF from other causes of dyspnoea. Statistical analysis was performed by SPSS version 17. Results: A total of 92 patients presenting with dyspnoea in the emergency department were studied. There were 38/92 (41.3%) males and 54/92 (58.7%) females, and the average age of the study population was 64 A +- 14.1 years. These patients had BNP levels and Doppler echocardiography done. The average BNP was found to be 1117.78 A +- 1445.74 pg/ml. In log transformation, the average was found to be 2.72 A +- 0.58. BNP value of 531 pg/ml was found to be the cut off to distinguish between cardiogenic and non-cardiogenic causes of dyspnoea. Conclusion: BNP value of 531 pg/ml can distinguish CHF from other conditions as a cause of dyspnoea in emergency. (author)

Microbial activity in bentonite buffers. Literature study

Energy Technology Data Exchange (ETDEWEB)

Ratto, M.; Itavaara, M.

2012-07-01

The proposed disposal concept for high-level radioactive wastes involves storing the wastes underground in copper-iron containers embedded in buffer material of compacted bentonite. Hydrogen sulphide production by sulphate-reducing prokaryotes is a potential mechanism that could cause corrosion of waste containers in repository conditions. The prevailing conditions in compacted bentonite buffer will be harsh. The swelling pressure is 7-8 MPa, the amount of free water is low and the average pore and pore throat diameters are small. This literature study aims to assess the potential of microbial activity in bentonite buffers. Literature on the environmental limits of microbial life in extreme conditions and the occurrence of sulphatereducing prokaryotes in extreme environments is reviewed briefly and the results of published studies characterizing microbes and microbial processes in repository conditions or in relevant subsurface environments are presented. The presence of bacteria, including SRBs, has been confirmed in deep groundwater and bentonite-based materials. Sulphate reducers have been detected in various high-pressure environments, and sulphate-reduction based on hydrogen as an energy source is considered a major microbial process in deep subsurface environments. In bentonite, microbial activity is strongly suppressed, mainly due to the low amount of free water and small pores, which limit the transport of microbes and nutrients. Spore-forming bacteria have been shown to survive in compacted bentonite as dormant spores, and they are able to resume a metabolically active state after decompaction. Thus, microbial sulphide production may increase in repository conditions if the dry density of the bentonite buffer is locally reduced. (orig.)

Establishing the cut-off score for remission and severity-ranges on the Psychotic Depression Assessment Scale (PDAS)

DEFF Research Database (Denmark)

Østergaard, Søren D; Rothschild, Anthony J; Flint, Alastair J

2016-01-01

BACKGROUND: The Psychotic Depression Assessment Scale (PDAS) is a rating scale dedicated to the measurement of severity in psychotic depression (PD). The aim of this study was to establish the PDAS cut-off for remission of PD as well as PDAS score-ranges for mild, moderate, and severe PD...... on the PDAS and the severity-ranges for mild, moderate, and severe PD were defined using the Clinical Global Impression - Severity scale (CGI-S) as reference by means of pair-wise receiver operating characteristic (ROC) analyses. Subsequently, it was tested whether remission on the PDAS could separate...... the effects of Olanzapine+Sertraline vs. Olanzapine+Placebo through an intention-to-treat, mixed-effects logistic regression of the data from STOP-PD. RESULTS: According to the ROC analyses, the ideal cut-off for remission of PD was a PDAS total score moderate...

Appraisal and standardization of curvilinear velocity (VCL) cut-off values for CASA analysis of Japanese quail (Coturnix japonica) sperm.

Science.gov (United States)

Farooq, U; Malecki, I A; Mahmood, M; Martin, G B

2017-06-01

One of the basic steps in objective analysis of sperm motility is the subdivision of a motile sperm population into slow, medium and rapid categories based on their velocity. However, for CASA analysis of quail sperm, the velocity values for categorization of slow, medium and rapid sperm have not yet been standardized. To identify the cut-off values of "velocity curvilinear" (VCL) for quail sperm categorization, we captured and analysed 22,300 tracks of quail sperm using SCA ® -CASA. The median and mean VCL values were 85 and 97 μm/s. To define the VCL cut-off values, we used two methods. In the first, we identified the upper (rapid sperm) and lower (slow sperm) cut-off values using: (i) median VCL ± 25% or ± 50% or ± 75% of median VCL value; (ii) first and third quartile values of VCL data (i.e. 25% cut-off setting); and (iii) 33% and 66% of VCL data. Among these settings, sperm categories and their corresponding motility characteristics recorded using the "25%" setting (i.e. slow ≤36 ≤ medium ≤154 ≤ rapid) were found the most realistic and coherent with male ranking by fertility. In the second method, we calculated heteroscedasticity in the total VCL data using PCA and the two-step clustering method. With this approach, the mean of the high and low clusters was 165 and 51 μm/s, respectively. Together, the mean from two methods suggested that, for SCA ® -CASA categorization of quail sperm, sperm should be classed as "rapid" at VCL ≥160 μm/s and "slow" at VCL ≤45 μm/s. © 2017 Blackwell Verlag GmbH.

Ten years of experience with transgastric necrosectomy for walled-off necrosis in acute pancreatitis

DEFF Research Database (Denmark)

Busse, Malene Just; Ainsworth, Alan Patrick

2015-01-01

: Acute pancreatitis with walled-off necrosis has a high mortality rate. Need for additional therapy following necrosectomy was associated with fatal outcome. Endocrine and exocrine insufficiency was often seen at follow-up. FUNDING: none. TRIAL REGISTRATION: The study was approved by the Danish Data....... Ten patients (20%) died during their admission to our department. In total, 18 (45%) patients developed late complications defined as endocrine and/or exocrine malfunction of the pancreas (diabetes (n = 10), exocrine insufficiency (n = 4), both diabetes and exocrine insufficiency (n = 4)). CONCLUSION......INTRODUCTION: The aim of this study was to report our results with open transgastric necrosectomy for walled-off necrosis in acute pancreatitis over a period of ten years. METHODS: Patients operated at the department from 2003 until 2012 were studied retrospectively. RESULTS: A total of 50 patients...

Organophilization and characterization of commercial bentonite clays

International Nuclear Information System (INIS)

Cunha, B.B. da; Lima, J.C.C.; Alves, A.M.; Araujo, E.M.; Melo, T.J.A. de

2012-01-01

Bentonite clay is a plastic changes resulting from volcanic ash, consisting mostly of montmorillonite. The state of Paraiba is a major source of bentonite clay from Brazil, where the main oil fields are located in Boa Vista and represents the largest national production of raw and beneficiated bentonite. Aimed at the commercial value of this type of clay and its high applicability in the polls, this article aims to make a comparison between two kinds of clay, a national (Brasgel) and other imported (Cloisite) from organophilization of two commercial bentonite, ionic surfactant with Praepagem WB, and characterize them by XRD, FTIR and TG / DTG. We observe that despite getting inferior properties, the clay presents national values very similar to those presented by imported clay. (author)

BaM bentonite and some of its properties

International Nuclear Information System (INIS)

Matal, Oldřich; Vávra Michal; Kachlík, Martin; Maca, Karel; Kotnour, Petr; Pospíšková, Ilona

2018-01-01

BaM bentonite is lime-magnesium bentonite of domestic origin. Its properties were measured experimentally with focus on the following parameters: composition, morphology and particle size distribution, powder bulk density, powder pressing parameters, shear strength, and water saturation. The findings will find use in nuclear safety assessments of engineered bentonite barriers in underground nuclear waste disposal facilities. (orig.)

Bentonite erosion. Laboratory studies

Energy Technology Data Exchange (ETDEWEB)

Jansson, Mats (Div. of Nuclear Chemistry, Royal Inst. of Technology, Stockholm (Sweden), School of Chemical Science and Engineering)

2009-11-15

This report covers the laboratory studies that have been performed at Nuclear Chemistry, KTH in the project 'Bentonite Erosion'. Many of the experiments in this report were performed to support the work of the modelling group and were often relatively simple. One of the experiment series was performed to see the impact of gravity and concentration of mono- and di-valent cations. A clay suspension was prepared in a test tube. A net was placed in contact with the suspension, the test tube was filled with solutions of different concentrations and the system was left overnight to settle. The tube was then turned upside down and the behaviour was visually observed. Either the clay suspension fell through the net or stayed on top. By using this method surprisingly sharp determinations of the Critical Coagulation (Flocculation) Concentration (CCC/CFC) could be made. The CCC/CFC of Ca2+ was for sodium montmorillonite determined to be between 1 and 2 mM. An artificial fracture was manufactured in order to simulate the real case scenario. The set-up was two Plexiglas slabs separated by 1 mm thick spacers with a bentonite container at one side of the fracture. Water was pumped with a very low flow rate perpendicular to bentonite container and the water exiting the fracture was sampled and analyzed for colloid content. The bentonite used was treated in different ways. In the first experiment a relatively montmorillonite rich clay was used while in the second bentonite where only the readily soluble minerals had been removed was used. Since Plexiglas was used it was possible to visually observe the bentonite dispersing into the fracture. After the compacted bentonite (1,000 kg/m3) had been water saturated the clay had expanded some 12 mm out into the fracture. As the experiment progressed the clay expanded more out into the fracture and seemed to fractionate in two different phases with less material in the outmost phase. A dark rim which was later analyzed to contain

Cut-Offs and Response Criteria for the Hospital Universitario La Princesa Index (HUPI and Their Comparison to Widely-Used Indices of Disease Activity in Rheumatoid Arthritis.

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Isidoro González-Álvaro

Full Text Available To estimate cut-off points and to establish response criteria for the Hospital Universitario La Princesa Index (HUPI in patients with chronic polyarthritis.Two cohorts, one of early arthritis (Princesa Early Arthritis Register Longitudinal [PEARL] study and other of long-term rheumatoid arthritis (Estudio de la Morbilidad y Expresión Clínica de la Artritis Reumatoide [EMECAR] including altogether 1200 patients were used to determine cut-off values for remission, and for low, moderate and high activity through receiver operating curve (ROC analysis. The areas under ROC (AUC were compared to those of validated indexes (SDAI, CDAI, DAS28. ROC analysis was also applied to establish minimal and relevant clinical improvement for HUPI.The best cut-off points for HUPI are 2, 5 and 9, classifying RA activity as remission if ≤2, low disease activity if >2 and ≤5, moderate if >5 and <9 and high if ≥9. HUPI's AUC to discriminate between low-moderate activity was 0.909 and between moderate-high activity 0.887. DAS28's AUCs were 0.887 and 0.846, respectively; both indices had higher accuracy than SDAI (AUCs: 0.832 and 0.756 and CDAI (AUCs: 0.789 and 0.728. HUPI discriminates remission better than DAS28-ESR in early arthritis, but similarly to SDAI. The HUPI cut-off for minimal clinical improvement was established at 2 and for relevant clinical improvement at 4. Response criteria were established based on these cut-off values.The cut-offs proposed for HUPI perform adequately in patients with either early or long term arthritis.

Cut-Offs and Response Criteria for the Hospital Universitario La Princesa Index (HUPI) and Their Comparison to Widely-Used Indices of Disease Activity in Rheumatoid Arthritis.

Science.gov (United States)

González-Álvaro, Isidoro; Castrejón, Isabel; Ortiz, Ana M; Toledano, Esther; Castañeda, Santos; García-Vadillo, Alberto; Carmona, Loreto

2016-01-01

To estimate cut-off points and to establish response criteria for the Hospital Universitario La Princesa Index (HUPI) in patients with chronic polyarthritis. Two cohorts, one of early arthritis (Princesa Early Arthritis Register Longitudinal [PEARL] study) and other of long-term rheumatoid arthritis (Estudio de la Morbilidad y Expresión Clínica de la Artritis Reumatoide [EMECAR]) including altogether 1200 patients were used to determine cut-off values for remission, and for low, moderate and high activity through receiver operating curve (ROC) analysis. The areas under ROC (AUC) were compared to those of validated indexes (SDAI, CDAI, DAS28). ROC analysis was also applied to establish minimal and relevant clinical improvement for HUPI. The best cut-off points for HUPI are 2, 5 and 9, classifying RA activity as remission if ≤2, low disease activity if >2 and ≤5), moderate if >5 and <9 and high if ≥9. HUPI's AUC to discriminate between low-moderate activity was 0.909 and between moderate-high activity 0.887. DAS28's AUCs were 0.887 and 0.846, respectively; both indices had higher accuracy than SDAI (AUCs: 0.832 and 0.756) and CDAI (AUCs: 0.789 and 0.728). HUPI discriminates remission better than DAS28-ESR in early arthritis, but similarly to SDAI. The HUPI cut-off for minimal clinical improvement was established at 2 and for relevant clinical improvement at 4. Response criteria were established based on these cut-off values. The cut-offs proposed for HUPI perform adequately in patients with either early or long term arthritis.

Quantum fields and Poisson processes: Interaction of a cut-off boson field with a quantum particle

International Nuclear Information System (INIS)

Bertrand, J.; Rideau, G.; Gaveau, B.

1985-01-01

The solution of the Schroedinger equation for a boson field interacting with a quantum particle is written as an expectation on a Poisson process counting the variations of the boson-occupation numbers for each momentum. An energy cut-off is needed for the expectation to be meaningful. (orig.)

Saturation of compacted bentonite under repository conditions: long-term experimental evidences

International Nuclear Information System (INIS)

Villar, M.V.; Martin, P.L.; Gomez-Espina, R.; Garcia-Sineriz, J.L.; Barcena, I.; Lloret, A.

2010-01-01

Document available in extended abstract form only. A current design for engineered barriers in the context of high-level radioactive waste disposal includes bentonite compacted blocks initially unsaturated. The heat released by the waste will induce high temperatures in the bentonite barrier. It is expected that full saturation of the buffer be reached before the dissipation of the thermal gradient. However, it still remains unclear whether the high temperatures around the canister would hinder the full saturation of the inner part of the barrier or just delay it. This paper summarises the information gathered in the last 15 years on the saturation of compacted FEBEX bentonite by means of different scale laboratory tests, a big-scale mock-up test and a real-scale in situ test, that were performed in order to simulate the conditions of the clay barrier in the repository and better understand the hydration/heating processes and their consequences on bentonite performance. FEBEX is a Spanish bentonite composed mainly of montmorillonite (about 92%). In the tests it has been used compacted with its hygroscopic water content (14%) at dry densities between 1.6 and 1.7 g/cm 3 , which is the range expected in the repository. For these densities the saturated permeability of the bentonite is about 3.10 -14 m/s and its swelling pressure 8 MPa. The FEBEX in situ test is being performed under natural conditions and at full scale within a drift excavated in the underground laboratory managed by NAGRA at the Grimsel Test Site (Switzerland). The thickness of the bentonite barrier is of 65 cm, and the surface heater temperature is 100 C. After five years of heating, and according to the sensors measurements, the bentonite closer to the heater had water contents below the initial ones, although they were recovering after the intense initial drying. On the contrary, for the same period of time, the sensors located at the same distance from the gallery wall, but in an area not

An optimal cut-off point for the calving interval may be used as an indicator of bovine abortions.

Science.gov (United States)

Bronner, Anne; Morignat, Eric; Gay, Emilie; Calavas, Didier

2015-10-01

The bovine abortion surveillance system in France aims to detect as early as possible any resurgence of bovine brucellosis, a disease of which the country has been declared free since 2005. It relies on the mandatory notification and testing of each aborting cow, but under-reporting is high. This research uses a new and simple approach which considers the calving interval (CI) as a "diagnostic test" to determine optimal cut-off point c and estimate diagnostic performance of the CI to identify aborting cows, and herds with multiple abortions (i.e. three or more aborting cows per calving season). The period between two artificial inseminations (AI) was considered as a "gold standard". During the 2006-2010 calving seasons, the mean optimal CI cut-off point for identifying aborting cows was 691 days for dairy cows and 703 days for beef cows. Depending on the calving season, production type and scale at which c was computed (individual or herd), the average sensitivity of the CI varied from 42.6% to 64.4%; its average specificity from 96.7% to 99.7%; its average positive predictive value from 27.6% to 65.4%; and its average negative predictive value from 98.7% to 99.8%. When applied to the French bovine population as a whole, this indicator identified 2-3% of cows suspected to have aborted, and 10-15% of herds suspected of multiple abortions. The optimal cut-off point and CI performance were consistent over calving seasons. By applying an optimal CI cut-off point to the cattle demographics database, it becomes possible to identify herds with multiple abortions, carry out retrospective investigations to find the cause of these abortions and monitor a posteriori compliance of farmers with their obligation to report abortions for brucellosis surveillance needs. Therefore, the CI could be used as an indicator of abortions to help improve the current mandatory notification surveillance system. Copyright © 2015 Elsevier B.V. All rights reserved.

Surface metallurgy of cemented carbide tools

International Nuclear Information System (INIS)

Chopra, K.L.; Kashyap, S.C.; Rao, T.V.; Rajagopalan, S.; Srivastava, P.K.

1983-01-01

Transition metal carbides, owing to their high melting point, hardness and wear resistance, are potential candidates for specific application in rockets, nuclear engineering equipment and cutting tools. Tungsten carbide sintered with a binder (either cobalt metal or a mixture of Co + TiC and/or TaC(NbC)) is used for cutting tools. The surface metallurgy of several commercially available cemented carbide tools was studied by Auger electron spectroscopy and X-ray photoelectron spectroscopy techniques. The tool surfaces were contaminated by adsorbed oxygen up to a depth of nearly 0.3 μm causing deterioration of the mechanical properties of the tools. Studies of fractured samples indicated that the tool surfaces were prone to oxygen adsorption. The fracture path passes through the cobalt-rich regions. The ineffectiveness of a worn cutting tool is attributed to the presence of excessive iron from the steel workpiece and carbon and oxygen in the surface layers of the tool. The use of appropriate hard coatings on cemented carbide tools is suggested. (Auth.)

Development and validation of optimal cut-off value in inter-arm systolic blood pressure difference for prediction of cardiovascular events.

Science.gov (United States)

Hirono, Akira; Kusunose, Kenya; Kageyama, Norihito; Sumitomo, Masayuki; Abe, Masahiro; Fujinaga, Hiroyuki; Sata, Masataka

2018-01-01

An inter-arm systolic blood pressure difference (IAD) is associated with cardiovascular disease. The aim of this study was to develop and validate the optimal cut-off value of IAD as a predictor of major adverse cardiac events in patients with arteriosclerosis risk factors. From 2009 to 2014, 1076 patients who had at least one cardiovascular risk factor were included in the analysis. We defined 700 randomly selected patients as a development cohort to confirm that IAD was the predictor of cardiovascular events and to determine optimal cut-off value of IAD. Next, we validated outcomes in the remaining 376 patients as a validation cohort. The blood pressure (BP) of both arms measurements were done simultaneously using the ankle-brachial blood pressure index (ABI) form of automatic device. The primary endpoint was the cardiovascular event and secondary endpoint was the all-cause mortality. During a median period of 2.8 years, 143 patients reached the primary endpoint in the development cohort. In the multivariate Cox proportional hazards analysis, IAD was the strong predictor of cardiovascular events (hazard ratio: 1.03, 95% confidence interval: 1.01-1.05, p=0.005). The receiver operating characteristic curve revealed that 5mmHg was the optimal cut-off point of IAD to predict cardiovascular events (p<0.001). In the validation cohort, the presence of a large IAD (IAD ≥5mmHg) was significantly associated with the primary endpoint (p=0.021). IAD is significantly associated with future cardiovascular events in patients with arteriosclerosis risk factors. The optimal cut-off value of IAD is 5mmHg. Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Gas Transport in Bentonite

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.; Gutierre-Rodrigo, V.; Martin, P. I.; Romero, F. J.; Barcala, J. M.

2013-07-01

The gas permeability of the Spanish FEBEX bentonite compacted at dry densities of between 1.4 and 1.8 g/cm{sup 3} with high water contents was measured for different confining, injection and back pressures. The results were compared with results obtained in previous investigations for lower degrees of saturation. It was checked that gas permeability was greatly affected by dry density, decreasing about three orders of magnitude when it increased from 1.5 to 1.8 g/cm{sup 3} for similar water content. The increase of water content caused also a decrease in gas permeability. It was found that both gas permeability and the relative gas permeability were mainly related to the accessible porosity. These relationships could be fitted to potential expressions with exponents between 3 and 4, as well as the relationship between intrinsic permeability and void ratio. For gas pressures below 1.2 MPa no effect of the injection or confining pressures on the value of permeability was detected. For a given confining pressure the permeability value decreased as the effective pressure increased, especially if the increase in effective pressure was due to a decrease in gas back pressure. It was checked that the Klinkenberg effect was not significant for this material in the range of pressures applied in the tests. The gas breakthrough pressure values in FEBEX saturated bentonite were determined for different dry densities. They increased clearly with dry density and were always higher than the swelling pressure of the bentonite. In high density samples gas flow tended to stop abruptly after breakthrough, whereas in lower density samples gas flow decreased gradually until a given pressure gradient was reached. The permeabilities computed after breakthrough (which usually did not stabilise) were inversely related to dry density. This would indicate that, even if the flow took place predominantly through preferential pathways that sometimes closed quickly after breakthrough and others

Gas Transport in Bentonite

International Nuclear Information System (INIS)

Villar, M. V.; Gutierrez-Rodrigo, V.; Martin, P. L.; Romero, F. J.; Barcala, J. M.

2013-01-01

The gas permeability of the Spanish FEBEX bentonite compacted at dry densities of between 1.4 and 1.8 g/cm 3 with high water contents was measured for different confining, injection and back pressures. The results were compared with results obtained in previous investigations for lower degrees of saturation. It was checked that gas permeability was greatly affected by dry density, decreasing about three orders of magnitude when it increased from 1.5 to 1.8 g/cm 3 for similar water content. The increase of water content caused also a decrease in gas permeability. It was found that both gas permeability and the relative gas permeability were mainly related to the accessible porosity. These relationships could be fitted to potential expressions with exponents between 3 and 4, as well as the relationship between intrinsic permeability and void ratio. For gas pressures below 1.2 MPa no effect of the injection or confining pressures on the value of permeability was detected. For a given confining pressure the permeability value decreased as the effective pressure increased, especially if the increase in effective pressure was due to a decrease in gas back pressure. It was checked that the Klinkenberg effect was not significant for this material in the range of pressures applied in the tests. The gas breakthrough pressure values in FEBEX saturated bentonite were determined for different dry densities. They increased clearly with dry density and were always higher than the swelling pressure of the bentonite. In high density samples gas flow tended to stop abruptly after breakthrough, whereas in lower density samples gas flow decreased gradually until a given pressure gradient was reached. The permeabilities computed after breakthrough (which usually did not stabilise) were inversely related to dry density. This would indicate that, even if the flow took place predominantly through preferential pathways that sometimes closed quickly after breakthrough and others remained

Microbial communities in bentonite formations and their interactions with uranium

International Nuclear Information System (INIS)

López-Fernández, Margarita; Fernández-Sanfrancisco, Omar; Moreno-García, Alberto; Martín-Sánchez, Inés; Sánchez-Castro, Iván; Merroun, Mohamed Larbi

2014-01-01

Highlights: • Microbial diversity of Spanish bentonites was studied. • High number of aerobe and facultative anaerobe microbes were isolated from bentonites. • Natural bentonite microbes are able to tolerate high U concentrations. • U is immobilized by the cells of the strain Rhodotorula mucilaginosa BII-R8 as U(VI) phosphates. - Abstract: A reliable performance assessment of deep geological disposal of nuclear waste depends on better knowledge of radionuclide interactions with natural microbes of geological formations (granitic rock, clay, salts) used to host these disposal systems. In Spain, clay deposits from Cabo de Gata region, Almeria, are investigated for this purpose. The present work characterizes the culture-dependent microbial diversity of two bentonite samples (BI and BII) recovered from Spanish clay deposits. The evaluation of aerobe and facultative anaerobe microbial populations shows the presence of a high number of cultivable bacteria (e.g. Stenotrophomonas, Micrococcus, Arthrobacter, Kocuria, Sphingomonas, Bacillus, Pseudomonas, etc.) affiliated to three phyla Proteobacteria, Actinobacteria, and Firmicutes. In addition, a pigmented yeast strain BII-R8 related to Rhodotorula mucilaginosa was also recovered from these formations. The minimal inhibitory concentrations of uranium for the growth of these natural isolates were found to range from 4 to 10.0 mM. For instance, strain R. mucilaginosa BII-R8 was shown to tolerate up to 8 mM of U. Flow cytometry studies indicated that the high U tolerance of this yeast isolate is a biologically mediated process. Microscopically dense intracellular and cell wall-bound precipitates were observed by Scanning Transmission Electron Microscopy-High-Angle Annular Dark-Field (STEM-HAADF). Energy Dispersive X-ray (EDX) element-distribution maps showed the presence of U and P within these accumulates, indicating the ability of cells to precipitate U as U(VI) phosphate minerals. Fundamental understanding of the

Microbial communities in bentonite formations and their interactions with uranium

Energy Technology Data Exchange (ETDEWEB)

López-Fernández, Margarita; Fernández-Sanfrancisco, Omar; Moreno-García, Alberto; Martín-Sánchez, Inés; Sánchez-Castro, Iván; Merroun, Mohamed Larbi, E-mail: merroun@ugr.es

2014-10-15

Highlights: • Microbial diversity of Spanish bentonites was studied. • High number of aerobe and facultative anaerobe microbes were isolated from bentonites. • Natural bentonite microbes are able to tolerate high U concentrations. • U is immobilized by the cells of the strain Rhodotorula mucilaginosa BII-R8 as U(VI) phosphates. - Abstract: A reliable performance assessment of deep geological disposal of nuclear waste depends on better knowledge of radionuclide interactions with natural microbes of geological formations (granitic rock, clay, salts) used to host these disposal systems. In Spain, clay deposits from Cabo de Gata region, Almeria, are investigated for this purpose. The present work characterizes the culture-dependent microbial diversity of two bentonite samples (BI and BII) recovered from Spanish clay deposits. The evaluation of aerobe and facultative anaerobe microbial populations shows the presence of a high number of cultivable bacteria (e.g. Stenotrophomonas, Micrococcus, Arthrobacter, Kocuria, Sphingomonas, Bacillus, Pseudomonas, etc.) affiliated to three phyla Proteobacteria, Actinobacteria, and Firmicutes. In addition, a pigmented yeast strain BII-R8 related to Rhodotorula mucilaginosa was also recovered from these formations. The minimal inhibitory concentrations of uranium for the growth of these natural isolates were found to range from 4 to 10.0 mM. For instance, strain R. mucilaginosa BII-R8 was shown to tolerate up to 8 mM of U. Flow cytometry studies indicated that the high U tolerance of this yeast isolate is a biologically mediated process. Microscopically dense intracellular and cell wall-bound precipitates were observed by Scanning Transmission Electron Microscopy-High-Angle Annular Dark-Field (STEM-HAADF). Energy Dispersive X-ray (EDX) element-distribution maps showed the presence of U and P within these accumulates, indicating the ability of cells to precipitate U as U(VI) phosphate minerals. Fundamental understanding of the

Influence factors of sand-bentonite mixtures on hydraulic conductivity

International Nuclear Information System (INIS)

Chen Yonggui; Ye Weimin; Chen Bao; Wan Min; Wang Qiong

2008-01-01

Buffer material is a very important part of the engineering barrier for geological disposal of high-level radioactive nuclear waste. Compacted bentonite is attracting greater attention as buffer and backfill material because it offer impermeability and swelling properties, but the pure compacted bentonite strength decreases with increasing hydration and these will reduce the buffer capability. To solve this problem, sand is often used to form compacted sand-bentonite mixtures (SBMs) providing high thermal conductivity, excellent compaction capacity, long-time stability, and low engineering cost. As to SBMs, hydraulic conductivity is a important index for evaluation barrier capability. Based on the review of research results, the factors affecting the hydraulic conductivity of SBMs were put forward including bentonite content, grain size distribution, moisture content, dry density, compacting method and energy, and bentonite type. The studies show that the hydraulic conductivity of SBMs is controlled by the hydraulic conductivity of the bentonite, it also decreases as dry density and bentonite content increase, but when the bentonite content reach a critical point, the influence of increasing bentonite to decrease the hydraulic conductivity is limited. A fine and well-graded SBMs is likely to have a lower hydraulic conductivity than a coarse and poorly graded material. The internal erosion or erodibility based on the grain size distribution of the SBMs has a negative effect on the final hydraulic conductivity. The lowest hydraulic conductivity is gained when the mixtures are compacted close to optimum moisture content. Also, the mixtures compacted at moisture contents slightly above optimum values give lower hydraulic conductivity than when compacted at slightly under the optimum moisture content. Finally, discussion was brought to importance of compaction method, compacting energy, and bentonite type to the hydraulic conductivity of SBMs. (authors)

Evaluation of bentonite alteration due to interactions with iron. Sensitivity analyses to identify the important factors for the bentonite alteration

International Nuclear Information System (INIS)

Sasamoto, Hiroshi; Wilson, James; Sato, Tsutomu

2013-01-01

Performance assessment of geological disposal systems for high-level radioactive waste requires a consideration of long-term systems behaviour. It is possible that the alteration of swelling clay present in bentonite buffers might have an impact on buffer functions. In the present study, iron (as a candidate overpack material)-bentonite (I-B) interactions were evaluated as the main buffer alteration scenario. Existing knowledge on alteration of bentonite during I-B interactions was first reviewed, then the evaluation methodology was developed considering modeling techniques previously used overseas. A conceptual model for smectite alteration during I-B interactions was produced. The following reactions and processes were selected: 1) release of Fe 2+ due to overpack corrosion; 2) diffusion of Fe 2+ in compacted bentonite; 3) sorption of Fe 2+ on smectite edge and ion exchange in interlayers; 4) dissolution of primary phases and formation of alteration products. Sensitivity analyses were performed to identify the most important factors for the alteration of bentonite by I-B interactions. (author)

Analysis of corrosion products of carbon steel in wet bentonite

International Nuclear Information System (INIS)

Osada, Kazuo; Nagano, Tetsushi; Nakayama, Shinichi; Muraoka, Susumu

1992-02-01

As a part of evaluation of the long-term durability for the overpack containers for high-level radioactive waste, we have conducted corrosion tests for carbon steel in wet bentonite, a candidate buffer material. The corrosion rates were evaluated by weight difference of carbon steel and corrosion products were analyzed by Fourier transform infrared spectroscopy (FT-IR) and colorimetry. At 40degC, the corrosion rate of carbon steel in wet bentonite was smaller than that in pure water. At 95degC, however, the corrosion rate in wet bentonite was much higher than that in pure water. This high corrosion rate in wet bentonite at 95degC was considered to result from evaporation of moisture in bentonite in contact with the metal. This evaporation led to dryness and then to shrinkage of the bentonite, which generated ununiform contact of the metal with bentonite. Probably, this ununiform contact promoted the local corrosion. The locally corroded parts of specimen in wet bentonite at 95degC were analyzed by Fourier transform infrared microspectroscopy (micro-FT-IR), and lepidocrocite γ-FeO(OH) was found as well as goethite α-FeO(OH). In wet bentonite at 95degC, hematite α-Fe 2 O 3 was identified by means of colorimetry. (author)

The analytic regularization ζ function method and the cut-off method in Casimir effect

International Nuclear Information System (INIS)

Svaiter, N.F.; Svaiter, B.F.

1990-01-01

The zero point energy associated to a hermitian massless scalar field in the presence of perfectly reflecting plates in a three dimensional flat space-time is discussed. A new technique to unify two different methods - the ζ function and a variant of the cut-off method - used to obtain the so called Casimir energy is presented, and the proof of the analytic equivalence between both methods is given. (author)

Bentonite as a waste isolation pilot plant shaft sealing material

International Nuclear Information System (INIS)

Daemen, J.; Ran, Chongwei

1996-12-01

Current designs of the shaft sealing system for the Waste Isolation Pilot Plant (WIPP) propose using bentonite as a primary sealing component. The shaft sealing designs anticipate that compacted bentonite sealing components can perform through the 10,000-year regulatory period and beyond. To evaluate the acceptability of bentonite as a sealing material for the WIPP, this report identifies references that deal with the properties and characteristics of bentonite that may affect its behavior in the WIPP environment. This report reviews published studies that discuss using bentonite as sealing material for nuclear waste disposal, environmental restoration, toxic and chemical waste disposal, landfill liners, and applications in the petroleum industry. This report identifies the physical and chemical properties, stability and seal construction technologies of bentonite seals in shafts, especially in a saline brine environment. This report focuses on permeability, swelling pressure, strength, stiffness, longevity, and densification properties of bentonites

Bentonite as a waste isolation pilot plant shaft sealing material

Energy Technology Data Exchange (ETDEWEB)

Daemen, J.; Ran, Chongwei [Univ. of Nevada, Reno, NV (United States)

1996-12-01

Current designs of the shaft sealing system for the Waste Isolation Pilot Plant (WIPP) propose using bentonite as a primary sealing component. The shaft sealing designs anticipate that compacted bentonite sealing components can perform through the 10,000-year regulatory period and beyond. To evaluate the acceptability of bentonite as a sealing material for the WIPP, this report identifies references that deal with the properties and characteristics of bentonite that may affect its behavior in the WIPP environment. This report reviews published studies that discuss using bentonite as sealing material for nuclear waste disposal, environmental restoration, toxic and chemical waste disposal, landfill liners, and applications in the petroleum industry. This report identifies the physical and chemical properties, stability and seal construction technologies of bentonite seals in shafts, especially in a saline brine environment. This report focuses on permeability, swelling pressure, strength, stiffness, longevity, and densification properties of bentonites.

The influence of clay drilling grout on the quality of well cementation

Energy Technology Data Exchange (ETDEWEB)

Romic, L; Martinko, B

1979-01-01

The influence of clay drilling grout on the behavior of the cement mixture during the cementing of casings is described. Experimental results are given which demonstrate that clay drill grout slows down the setting of the cement mixture, lowers the durability of cement stone and its adherence to the well's walls, and changes the rheological properties and viscosity of the cement mixture. Separating devices, which prevent the mixing of the clay drilling grout and the cement solutions during the cementation process, are recommended.

Seismic analysis of the frame structure reformed by cutting off column and jacking based on stiffness ratio

Science.gov (United States)

Zhao, J. K.; Xu, X. S.

2017-11-01

The cutting off column and jacking technology is a method for increasing story height, which has been widely used and paid much attention in engineering. The stiffness will be changed after the process of cutting off column and jacking, which directly affects the overall seismic performance. It is usually necessary to take seismic strengthening measures to enhance the stiffness. A five story frame structure jacking project in Jinan High-tech Zone was taken as an example, and three finite element models were established which contains the frame model before lifting, after lifting and after strengthening. Based on the stiffness, the dynamic time-history analysis was carried out to research its seismic performance under the EL-Centro seismic wave, the Taft seismic wave and the Tianjin artificial seismic wave. The research can provide some guidance for the design and construction of the entire jack lifting structure.

Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

Directory of Open Access Journals (Sweden)

Kumar Sujeet

2014-12-01

Full Text Available Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swell increased and the free swell index decreased with the addition of 8 % phosphogypsum to the bentonite + 8 % lime mix. The unconfined compressive strength of the bentonite + 8 % lime increased with the addition of 8 % phosphogypsum as well as an increase in the curing period up to 14 days. The liquid limit and plastic limit of the bentonite + 8 % lime increased, whereas the plasticity index remained constant with the addition of 8 % phosphogypsum. The California bearing ratio, modulus of subgrade reaction, and secant modulus increased for the bentonite stabilized with lime and phosphogypsum. The coefficient of the consolidation of the bentonite increased with the addition of 8 % lime and no change with the addition of 8 % phosphogypsum.

Reactivity of Ordinary Portland Cement (OPC) grout and various lithologies from the Harwell research site

International Nuclear Information System (INIS)

Milodowski, A.E.; George, I.A.; Bloodworth, A.J.; Robins, N.S.

1985-08-01

Ordinary Portland Cement (OPC) has been used in the completion of boreholes on the Harwell Research Site, AERE, Oxfordshire. The purpose of this study was to examine the effect of OPC and the alkaline pore fluids generated during its setting on the various lithological types encountered in the boreholes. To facilitate this, samples of core representing the various rock types were selected and cement-rock composites were prepared from these in the laboratory to simulate the borehole cements. After a curing period of 15 months the cores and associated cement plugs were examined for any signs of reactivity or bonding. The best cement-rock bonding was shown by naturally well-cemented sandstone and limestone lithologies. Although no significant chemical reaction was seen to have occurred between OPC and rock, the OPC appears able to bind onto the rock surface because of the rigidity of the rock surface. Therefore, the best cement rock bonding and seal with OPC may be expected in the limestones of the Great Oolite Group, Inferior Oolite Group and parts of the Corallian Beds. Because of the reactivity of OPC towards certain lithologies a better borehole seal in such a sedimentary sequence might be achieved using a bentonite backfill in those parts of the sequence which either react with or bond only weakly to OPC. (author)

Evaluation for swelling characteristics of buffer and backfill materials for high-level nuclear waste disposal. Influence of sand-bentonite content and cation compositions in bentonite

International Nuclear Information System (INIS)

Komine, Hideo; Ogata, Nobuhide

1999-01-01

Compacted bentonite and sand-bentonite mixture are attracting greater attention as buffer and backfill materials for disposal pits and access tunnels in the underground facilities for repositories of high-level nuclear waste. Buffer and backfill materials must have the swelling characteristics and are expected to fill up the space between these materials and surrounding ground by swelling. This role is called as 'Self-sealing'. To design the specifications, such as dry density, bentonite content and size, of buffer and backfill materials for the disposal facilities of high-level nuclear wastes described above, we must evaluate the swelling characteristics of compacted bentonite and sand-bentonite mixtures. For this purpose, this study proposed the evaluation formula for swelling characteristics of buffer and backfill materials containing bentonite. This study derived new equations for evaluating the relationship between the swelling deformation of compacted bentonite and sand-bentonite mixtures, and the swelling behavior of montmorillonite minerals, which are swelling clay minerals. This study also proposed new equations for evaluating the ion compositions of bentonite, ion concentration of pore water and the specific surface of bentonite, which significantly influence the swelling characteristics of buffer and backfill materials. The evaluation formula proposed in this study is presented by combining the above-mentioned new equations with theoretical equations, of which are the Gouy-Chapman diffuse double layer theory and the van der Waals force, of repulsive and attractive forces of montmorillonite minerals. (author)

Endoscopic treatment of multilocular walled-off pancreatic necrosis with the multiple transluminal gateway technique.

Science.gov (United States)

Jagielski, Mateusz; Smoczyński, Marian; Adrych, Krystian

2017-06-01

The development of minimally invasive techniques allowed access to the necrotic cavity through transperitoneal, retroperitoneal, transmural and transpapillary routes. The choice of access to walled-off pancreatic necrosis (WOPN) should depend not only on the spread of necrosis, but also on the experience of the clinical center. Herein we describe treatment of a patient with multilocular symptomatic walled-off pancreatic necrosis using minimally invasive techniques. The single transmural access (single transluminal gateway technique - SGT) to the necrotic collection of the patient was ineffective. The second gastrocystostomy was performed using the same minimally invasive technique as an extra way of access to the necrosis (multiple transluminal gateway technique - MTGT). In the described case the performance of the new technique consisting in endoscopic multiplexing transmural access (MTGT) was effective enough and led to complete recovery of the patient.

Safety case approach for a KBS-3 type repository in crystalline rock

International Nuclear Information System (INIS)

Pastina, Barbara; Lehikoinen, Jarmo; Puigdomenech, Ignasi

2012-01-01

Barbara Pastina of Saanio and Riekkola described the approach to considering cementitious materials in a safety case for a KBS-3 repository in Finland. In this concept, cements will be used predominantly as tunnel plugs and seals. Part of the Finnish approach has involved identifying the cement-related FEPs. For example, FEPs representing the effects of cement on spent fuel, on the canister and on radionuclide transport include: - Fuel matrix dissolution at high pH. - Copper corrosion at high pH. - Radionuclide speciation and solubility at high pH. - Radionuclide sorption and diffusion at high pH. - Radionuclide transport due to organic materials (e.g. super-plasticisers). - Colloid formation at a high pH plume front. FEPs representing the effects of cement on bentonite in the buffer and backfill include: - Potential changes in swelling pressure due to mass loss, decrease in clay density, and precipitation of secondary minerals. - Potential cracking and increase of hydraulic conductivity due to cementation. - Increase of the cation exchange capacity due to the loss of silica from the montmorillonite structure. Amongst the cement-related FEPs, the main concerns are related to effects on the performance of the bentonite buffer. Cement-bentonite interactions are complex, there are few experimental data, and there are significant modelling uncertainties (e.g. limited knowledge about the reactions that may occur and their rates, and the effects of temperature). Accepting the existence of various uncertainties, preliminary modelling studies performed using the TOUGHREACT code illustrate the potential for porosity reduction and clogging of porosity in bentonite affected by cementitious pore waters. The modelling also suggests that that the high pH of the pore waters moving from the cementitious materials into the bentonite may be rapidly lowered as a result of reactions with the bentonite close to the cement-bentonite interface. Taking account of the various research and

Defining the optimal cut-off values for liver enzymes in diagnosing blunt liver injury.

Science.gov (United States)

Koyama, Tomohide; Hamada, Hirohisa; Nishida, Masamichi; Naess, Paal A; Gaarder, Christine; Sakamoto, Tetsuya

2016-01-25

Patients with blunt trauma to the liver have elevated levels of liver enzymes within a short time post injury, potentially useful in screening patients for computed tomography (CT). This study was performed to define the optimal cut-off values for serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in patients with blunt liver injury diagnosed with contrast enhanced multi detector-row CT (CE-MDCT). All patients admitted from May 2006 to July 2013 to Teikyo University Hospital Trauma and Critical Care Center, and who underwent abdominal CE-MDCT within 3 h after blunt trauma, were retrospectively enrolled. Using receiver operating characteristic (ROC) curve analysis, the optimal cut-off values for AST and ALT were defined, and sensitivity and specificity were calculated. Of a total of 676 blunt trauma patients 64 patients were diagnosed with liver injury (Group LI+) and 612 patients without liver injury (Group LI-). Group LI+ and LI- were comparable for age, Revised Trauma Score, and Probability of survival. The groups differed in Injury Severity Score [median 21 (interquartile range 9-33) vs. 17 (9-26) (p tool for CT scan in patients otherwise eligible for observation only or as a transfer criterion to a facility with CT scan capability.

Colloid chemical aspects of the ''confined bentonite concept''

International Nuclear Information System (INIS)

Bell, J.C. Le

1978-03-01

Measurements of the amount of particles released from a bentonite gel by light scattering and visual inspection show that while particles are released in distilled water, the gel will be coagulated if in contact with ground water and consequently the release of particles is negligibly small. Studies of sedimentation volumes by ultracentrifugation also clearly indicate that the bentonite in contact with ground water under the repository pressure will form a completely stable coagulated gel. The swelling of confined bentonite was studied in an ''artificial crack'' of width 0.5 mm. The bentonite flowed readily into this crack and into the much narrower crack formed when the cell was broken. The swelling properties of the bentonite at the repository depth are discussed. It is argued that the gel, if sufficient volume is available, will swell spontaneously to a volume that is approximately 30 % larger than the initial one and then form a stable, coagulated gel containing 30-35 % water in equilibrium with the ground water. Investigations of the diffusion of colloidal matter (sodium lignosulphonate molecules of mean diameter 6 nm) and calcium ions into a dilute bentonite gel show that colloidal matter very probably will have a negligible rate of diffusion while the calcium ions diffuse rapidly. This implies that the initial bentonite gel which is partially in its sodium form will be completely exchanged to its calcium form when brought into contact with ground water which ensures that it will remain coagulated even in its swollen state

Physicochemical, mineralogical and mechanical properties of domestic bentonite and bentonite-sand mixture as a buffer material in the high-level waste repository

International Nuclear Information System (INIS)

Cho, Won Jin; Lee, Jae Owan; Kang, Chul Hyung; Chun, Kwan Sik

1999-09-01

The physicochemical properties such as specific weight, free swell rate, chemical composition, cation exchange capacity (CEC), surface area and distribution coefficient of Kyunggju bentonite were measured, and the mineralogical analysis was performed to investigate the mineralogical composition. For the compacted bentonite and the mixture of bentonite and sand, the liquid and plastic limit, the linear shrinkage, and compaction property, the compression property, the shear property, and the consolidation property were investigated and analyzed. The bentonite contains montmorillonite (70 percent), feldspar (29 percent), and small amounts of quartz(-1 percent). The compressive strengths of bentonites are increased from 0.53 MPa to 8.83 MPa rapidly with increasing dry density of 1.4 g/cm 3 to 1.8 g/cm 3 . The cohesion and internal friction angles of bentonites with the dry density of 1.4 g/cm 3 to 1.8 g/cm 3 are in the range of 500 to 1100 kPa and 27 to 50 degree, respectively. (Author). 21 refs., 20 tabs., 46 figs

Physicochemical, mineralogical and mechanical properties of domestic bentonite and bentonite-sand mixture as a buffer material in the high-level waste repository

Energy Technology Data Exchange (ETDEWEB)

Cho, Won Jin; Lee, Jae Owan; Kang, Chul Hyung; Chun, Kwan Sik

1999-09-01

The physicochemical properties such as specific weight, free swell rate, chemical composition, cation exchange capacity (CEC), surface area and distribution coefficient of Kyunggju bentonite were measured, and the mineralogical analysis was performed to investigate the mineralogical composition. For the compacted bentonite and the mixture of bentonite and sand, the liquid and plastic limit, the linear shrinkage, and compaction property, the compression property, the shear property, and the consolidation property were investigated and analyzed. The bentonite contains montmorillonite (70 percent), feldspar (29 percent), and small amounts of quartz(-1 percent). The compressive strengths of bentonites are increased from 0.53 MPa to 8.83 MPa rapidly with increasing dry density of 1.4 g/cm{sup 3} to 1.8 g/cm{sup 3}. The cohesion and internal friction angles of bentonites with the dry density of 1.4 g/cm{sup 3} to 1.8 g/cm{sup 3} are in the range of 500 to 1100 kPa and 27 to 50 degree, respectively. (Author). 21 refs., 20 tabs., 46 figs.

Bentonite-amended soils special study

International Nuclear Information System (INIS)

1990-10-01

This report presents the results of a two-phased special study to evaluate the viability of soil amended with a high percentage of bentonite as an infiltration barrier in the cover of Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cells. Phase I of the study was initiated in order to examine the feasibility of using bentonite-amended soils as a cover component on sideslopes and topslopes. The Phase I objectives were to test a variety of materials to determine if low hydraulic conductivities were achievable in materials exhibiting sufficient strength and to select suitable materials for further testing. Phase II objectives were to (1) optimize designs -- test materials with various percentages of bentonite added; (2) provide design recommendations; (3) address constructibility concerns; and (4) evaluate long-term performance with respect to desiccation effects on the amended materials

Physico-chemical properties of water in bentonite

International Nuclear Information System (INIS)

Torikai, Yuji; Sato, Seichi; Ohashi, Hiroshi

1994-01-01

As a part of safety analysis on ground layer disposal, in order to estimate nuclides migration behavior from engineering shielding materials, it is required to modelize migration process of nuclides in bentonite and chemical species relating to corrosion, to estimate solubility and to specify application condition of geochemical calculation code. In this study, as a part of elucidation of nuclide migration process, physico-chemical properties of water in bentonite and montmorillonite using steam pressure method were determined. As a result, following items were found: (1) Even if 1/3 of water in bentonite is near free water, it is far from a region dealable with dilute solution in the electrolyte solution theory. And, (2) the water in bentonite has generally small activity in comparison with dilute solution, then has smaller solubility than estimation value of calculation code. (G.K.)

Modelling interaction of deep groundwaters with bentonite and radionuclide speciation

International Nuclear Information System (INIS)

Wanner, H.

1986-04-01

In the safety analysis recently reported for a potential Swiss high-level waste repository, radionuclide speciation and solubility limits are calculated for expected granitic groundwater conditions. With the objective of deriving a more realistic description of radionuclide release from the near-field, an investigation has been initiated to quantitatively specify the chemistry of the near-field. In the Swiss case, the main components of the near-field are the glass waste-matrix, a thick steel canister horizontally emplaced in a drift, and a backfill of highly compacted sodium bentonite. This report describes a thermodynamic model which is used to estimate the chemical composition of the pore water in compacted sodium bentonite. Solubility limits and speciation of important actinides and the fission product technetium in the bentonite pore water are then calculated. The model is based on available experimental data on the interaction of sodium bentonite and groundwater and represents means of extrapolation from laboratory data to repository conditions. The modelled composition of the pore water of compacted sodium bentonite, as well as the various compositions resulting from the long-term extrapolation, are used to estimate radionuclide solubilities in the near-field of a deep repository. From the chemical point of view, calcium bentonite seems to be more stable than sodium bentonite in the presence of Swiss Reference Groundwater. Since the effect of calcium bentonite on the groundwater chemical composition will be considerably less marked than that of sodium bentonite, especially with respect to key parameters for the nuclide speciation like carbonate concentration and pH, the use of calcium bentonite instead of sodium bentonite will improve the reliability in the prediction of source terms for radionuclide transport in the geosphere. (author)

Diffusion behavior for Se and Zr in sodium-bentonite

International Nuclear Information System (INIS)

Sato, Haruo; Yui, Mikazu; Yoshikawa, Hideki

1995-01-01

Apparent diffusion coefficients for Se and Zr in bentonite were measured by in-diffusion method at room temperature using water-saturated sodium-bentonite, Kunigel V1 reg-sign containing 50wt% Na-smectite as a major mineral was used as the bentonite material. The experiments were carried out in the dry density range of 400--1,800 kg/m 3 . Bentonite samples were immersed with distilled water and saturated before the experiments. The experiments for Se were carried out under N 2 atmospheric condition (O 2 : 2.5ppm). Those for Zr were carried out under aerobic condition. The apparent diffusion coefficients decrease with increasing density of the bentonite. Since dominant species of Se in the pore water is predicted to be SeO 3 2- , Se may be retarded by anion-exclusion because of negative charge on the surface of the bentonite and little sorption. The dominant species of Zr in the porewater is predicted to be Zr(OH) 5 - or HZrO 3 - . Distribution coefficient measured for Zr on the bentonite was about 1.0 m 3 /kg from batch experiments. Therefore, the retardation may be caused by combination of the sorption and the anion-exclusion. A modeling for the diffusion mechanisms in the bentonite were discussed based on an electric double layer theory. Comparison between the apparent diffusion coefficients predicted by the model and the measured ones shows a good agreement

Adsorption behavior of 99Tc in Ca-bentonite

International Nuclear Information System (INIS)

Liu Dejun; Fan Xianhua; Zhang Yingjie; Yao Jun; Zhou Duo; Wang Yong

2004-01-01

The adsorption behaviors of 99 Tc in bentonite were studied with batch methods under aerobic and anoxic conditions. The adsorption ratios is about 1.47 mL/g under aerobic conditions. The adsorption ratio of 99 Tc in bentonite is not affected by pH in the range of 5-12 and the CO 3 2- , Fe 3+ concentrations in the range of 10 -8 -10 -2 mol/L in the solution. The adsorption ratio of Tc in bentonite increases with the increase of the mass percent of Fe 2 O 3 and Fe 3 O 4 and the Fe 2+ concentration in the range of 10 -8 -10 -2 mol/L. Tc exists ainly in the form of Tc(VII) after the adsorption equilibriums. The adsorption ratio of Tc in bentonite increase with the increase of the mass percent of Fe and Tc exists mainly in the form of Tc(VII) after the adsorption equilibriums. The adsorption ratio of Tc in bentonite is about 84.84 mL/g under anoxic conditions. The adsorption ratios of 99 Tc in bentonite decreases with the increase of pH in the range of 5-12 and the CO 3 2- concentration in the range of 10 -8 -10 -2 mol/L in the solution. The adsorption ratio of Tc in bentonite increases with the increase of the Fe 3+ , Fe 2+ concentration in the range of 10 -8 -10 -2 mol/L and the mass percent of Fe, Fe 2 O 3 and Fe 3 O 4 . Tc exists mainly in the form of Tc(IV) after the adsorption equilibriums. The adsorption isotherms of TcO 4 - in bentonite are all in fairly agree with the Freundlich's equation under aerobic and anoxic conditions. (authors)

Optimization of acid-activated bentonites on bleaching of cotton oil

International Nuclear Information System (INIS)

Lacin, O.; Sayan, E.; Kirali, E.G.

2013-01-01

Bentonites are commonly used adsorbent on bleaching cotton oil to produce edible oil products. Bleaching capacities of neutralized cotton oil were investigated with acid-activated Arguvan and Kursunlu bentonites. Two models for acid activation of the bentonites were developed by using a full factorial experimental design and central composite design. The parameters used to develop these models were contact time, solid to liquid ratio, acid concentration and moisture of bentonite. By using a constrained optimization program, the maximum bleaching capacities of neutralized cotton oil were determined as 99.99% and 48.5% for Arguvan and Kursunlu, respectively. Optimum results showed that Turkish bentonites (especially Arguvan bentonite) have high bleaching ability and they can be used efficiently to bleach neutralized cotton oil by considering the favorable volume weight, capacity of oil adsorbed and filtration rate. (author)

Quantitative estimation of myocardial thickness by the wall thickness map with Tl-201 myocardial SPECT and its clinical use

International Nuclear Information System (INIS)

Sekiai, Yasuhiro; Sawai, Michihiko; Murayama, Susumu

1988-01-01

To estimate the wall thickness of left ventricular myocardium objectively and quantitatively, we adopted the device of wall thickness map (WTM) with Tl-201 myocardial SPECT. For validation on measuring left ventricular wall thickness with SPECT, fundamental studies were carried out with phantom models, and clinical studies were performed in 10 cases comparing the results from SPECT with those in echocardiography. To draw the WTM, left ventricular wall thickness was measured using the cut off method from SPECT images obtained at 5.6 mm intervals from the base and middle of left ventricle: short-axis image for the base and middle of left ventricle and vertical and horizontal long-axis images for the apical region. Wall thickness was defined from the number of pixel above the cut off level. Results of fundamental studies disclosed that it is impossible to evaluate the thickness of less than 10 mm by Tl-201 myocardial SPECT but possible to discriminate wall thickness of 10 mm, 15 mm, and 20 mm by Tl-201 myocardial SPECT. Echocardiographic results supported the validity of WTM, showing a good linear correlation (r = 0.96) between two methods on measuring wall thickness of left ventricle. We conclude that the WTM applied in this report may be useful for objective and quantitative estimation of myocardial hypertrophy. (author)

An assessment of the impact of the long term evolution of engineered structures on the safety-relevant functions of the bentonite buffer in a HLW repository

International Nuclear Information System (INIS)

Savage, D.

2014-07-01

, consisting of only 2 vol.-% of the total bentonite in the canister zone. Removing the rails prior to closure reduces this effect to 1 vol.-%. At the external margin of the bentonite, alteration of the buffer and sealing element adjacent to the concrete liner is 2 cm in thickness (4 vol.-%) at 100 ka. The hydraulic conductivity of this zone is decreased. The porosity and swelling pressure decrease to zero over a few hundreds to a thousand years due to alteration of montmorillonite. The mineralogical composition is characterised by a sequence of calcite, C-(A)-S-H minerals, Ca-zeolites, sepiolite and saponite clays, with C-S-H minerals forming nearest the cement contact, and other minerals such as zeolites and clays forming further towards the canister. The concrete liner itself may degrade via conversion of portlandite and C-S-H gel to ettringite with a consequent increase in porosity, reaching a few percent over 100 ka. For the sealing element, there are steel reinforcement arches, along with steel mesh, anchors and rails. A maximum of 5 vol.-% of bentonite could be transformed to non-swelling silicates. Removing the rails prior to closure reduces this effect to 4 vol.-%. At 100 ka, the canister is entirely degraded to iron oxyhydroxides and in the surrounding bentonite, montmorillonite is totally converted to non-swelling Fe-silicates. The original porosity and hydraulic conductivity are preserved, but the swelling pressure is decreased to zero. This altered zone is 45 cm thick and extends to the bentonite zone altered by interaction with the concrete liner. Alteration of the buffer and sealing element adjacent to the concrete liner is estimated to be 20 cm thick (35 vol.-%) at 100 ka. The porosity and hydraulic conductivity of this zone are unchanged, but with zero swelling pressure due to removal of montmorillonite. The mineralogical composition of this zone is characterised by a sequence of calcite, C-(A)-S-H minerals, Ca-zeolites, sepiolite and saponite clays, with C

An assessment of the impact of the long term evolution of engineered structures on the safety-relevant functions of the bentonite buffer in a HLW repository

Energy Technology Data Exchange (ETDEWEB)

Savage, D.

2014-07-15

, consisting of only 2 vol.-% of the total bentonite in the canister zone. Removing the rails prior to closure reduces this effect to 1 vol.-%. At the external margin of the bentonite, alteration of the buffer and sealing element adjacent to the concrete liner is 2 cm in thickness (4 vol.-%) at 100 ka. The hydraulic conductivity of this zone is decreased. The porosity and swelling pressure decrease to zero over a few hundreds to a thousand years due to alteration of montmorillonite. The mineralogical composition is characterised by a sequence of calcite, C-(A)-S-H minerals, Ca-zeolites, sepiolite and saponite clays, with C-S-H minerals forming nearest the cement contact, and other minerals such as zeolites and clays forming further towards the canister. The concrete liner itself may degrade via conversion of portlandite and C-S-H gel to ettringite with a consequent increase in porosity, reaching a few percent over 100 ka. For the sealing element, there are steel reinforcement arches, along with steel mesh, anchors and rails. A maximum of 5 vol.-% of bentonite could be transformed to non-swelling silicates. Removing the rails prior to closure reduces this effect to 4 vol.-%. At 100 ka, the canister is entirely degraded to iron oxyhydroxides and in the surrounding bentonite, montmorillonite is totally converted to non-swelling Fe-silicates. The original porosity and hydraulic conductivity are preserved, but the swelling pressure is decreased to zero. This altered zone is 45 cm thick and extends to the bentonite zone altered by interaction with the concrete liner. Alteration of the buffer and sealing element adjacent to the concrete liner is estimated to be 20 cm thick (35 vol.-%) at 100 ka. The porosity and hydraulic conductivity of this zone are unchanged, but with zero swelling pressure due to removal of montmorillonite. The mineralogical composition of this zone is characterised by a sequence of calcite, C-(A)-S-H minerals, Ca-zeolites, sepiolite and saponite clays, with C

Cut-off scaling of high-harmonic generation driven by a femtosecond visible optical parametric amplifier

International Nuclear Information System (INIS)

Cirmi, Giovanni; Lai, Chien-Jen; Granados, Eduardo; Huang, Shu-Wei; Sell, Alexander; Hong, Kyung-Han; Moses, Jeffrey; Keathley, Phillip; Kärtner, Franz X

2012-01-01

We studied high-harmonic generation (HHG) in Ar, Ne and He gas jets using a broadly tunable, high-energy optical parametric amplifier (OPA) in the visible wavelength range. We optimized the noncollinear OPA to deliver tunable, femtosecond pulses with 200-500 µJ energy at the 1 kHz repetition rate with excellent spatiotemporal properties, suitable for HHG experiments. By tuning the central wavelength of the OPA while keeping other parameters (energy, duration and beam size) constant, we experimentally studied the scaling law of cut-off energy with the driver wavelength in helium. Our measurements show a λ 1.7+0.2 dependence of the HHG cut-off photon energy over the full visible range in agreement with previous experiments of near- and mid-IR wavelengths. By tuning the central wavelength of the driver source, the high-order harmonic spectra in the extreme ultraviolet cover the full range of photon energy between ∼25 and ∼100 eV. Due to the high coherence intrinsic in HHG, as well as the broad and continuous tunability in the extreme UV range, a high energy, high repetition rate version of this source might be an ideal seed for free electron lasers.

bentonite-sand mixture as new backfill/buffer material

International Nuclear Information System (INIS)

Cui Suli; Liu Jisheng; Zhang Huyuan; Liang Jian

2008-01-01

The mixture of bentonite and quartz sand is suggested as a new backfill/buffer material for geological disposal of HLW. To improve the further design of underground laboratory and in-situ industrial construction test, the optimization of sand addition to bentonite is focused at present research stage. Based on summarizing the research results abroad, laboratory tests were conducted on the mixture of GMZ001 bentonite and quartz sand, such as compaction test and swelling tests etc. Test data shows that GMZ bentonite-sand mixture exhibits a favorite compaction with a 30% sand addition, a highest swelling pressure with a 20% sand addition, and a decreasing plasticity with increases in sand addition and pore liquid concentration. (authors)

Fundamental properties of monolithic bentonite buffer material formed by cold isostatic pressing for high-level radioactive waste repository

International Nuclear Information System (INIS)

Kawakami, S.; Yamanaka, Y.; Kato, K.; Asano, H.; Ueda, H.

1999-01-01

The methods of fabrication, handling, and emplacement of engineered barriers used in a deep geological repository for high level radioactive waste should be planned as simply as possible from the engineering and economic viewpoints. Therefore, a new concept of a monolithic buffer material around a waste package have been proposed instead of the conventional concept with the use of small blocks, which would decrease the cost for buffer material. The monolithic buffer material is composed of two parts of highly compacted bentonite, a cup type body and a cover. As the forming method of the monolithic buffer material, compaction by the cold isostatic pressing process (CIP) has been employed. In this study, monolithic bentonite bodies with the diameter of about 333 mm and the height of about 455 mm (corresponding to the approx. 1/5 scale for the Japanese reference concept) were made by the CIP of bentonite powder. The dry densities: ρd of the bodies as a whole were measured and the small samples were cut from several locations to investigate the density distribution. The swelling pressure and hydraulic conductivity as function of the monolithic body density for CIP-formed specimens were also measured. High density (ρd: 1.4--2.0 Mg/m 3 ) and homogeneous monolithic bodies were formed by the CIP. The measured results of the swelling pressure (3--15 MPa) and hydraulic conductivity (0.5--1.4 x 10 -13 m/s) of the specimens were almost the same as those for the uniaxial compacted bentonite in the literature. It is shown that the vacuum hoist system is an applicable handling method for emplacement of the monolithic bentonite

Case study installation of a HDPE curtain wall with sheetpile tie-in on both ends

International Nuclear Information System (INIS)

Schindler, R.M.; Maltese, P.C.

1997-01-01

The plans for eliminating the off-site migration of non-aqueous phase liquid (NAPL) from a refinery into a nearby river included the installation of a High Density Polyethylene (HDPE) curtain wall and an underdrain system. A 640 m (2100 lineal feet) HDPE Curtain Wall was installed along the river boundary, tying into an existing sheet pile wall on both ends. The wall varied from approximately 4.5 m (15 feet) deep at the northern end to about 7 m (23 feet) deep at the southern end, running approximately 3 to 3.6 m (10 to 12 feet) inland of an existing wooden bulkhead. The curtain wall was successfully installed through a slurry supported trench. A 930 m (3050 lineal feet) interception/collection trench was installed parallel to the HDPE Curtain Wall, continuing on beyond the curtain wall on the southern end. The depth of the trench varied from approximately 3 to 4 m (10 to 13 feet) deep. A 20.32 cm (8 inch) diameter perforated HDPE header pipe was placed in the trench to convey groundwater and product to two sumps. The trench is 53.34 cm (21 inches) wide and contained aggregate to approximately 0.9 m (3 feet) below ground. This work was accomplished using the bio-polymer slurry drainage trench (BP Drain) technique. This paper briefly describes the construction methods utilized during this project, specifically HDPE curtain wall installation thru a bentonite slurry and tie-in to the existing sheet pile wall

Soft sensor for real-time cement fineness estimation.

Science.gov (United States)

Stanišić, Darko; Jorgovanović, Nikola; Popov, Nikola; Čongradac, Velimir

2015-03-01

This paper describes the design and implementation of soft sensors to estimate cement fineness. Soft sensors are mathematical models that use available data to provide real-time information on process variables when the information, for whatever reason, is not available by direct measurement. In this application, soft sensors are used to provide information on process variable normally provided by off-line laboratory tests performed at large time intervals. Cement fineness is one of the crucial parameters that define the quality of produced cement. Providing real-time information on cement fineness using soft sensors can overcome limitations and problems that originate from a lack of information between two laboratory tests. The model inputs were selected from candidate process variables using an information theoretic approach. Models based on multi-layer perceptrons were developed, and their ability to estimate cement fineness of laboratory samples was analyzed. Models that had the best performance, and capacity to adopt changes in the cement grinding circuit were selected to implement soft sensors. Soft sensors were tested using data from a continuous cement production to demonstrate their use in real-time fineness estimation. Their performance was highly satisfactory, and the sensors proved to be capable of providing valuable information on cement grinding circuit performance. After successful off-line tests, soft sensors were implemented and installed in the control room of a cement factory. Results on the site confirm results obtained by tests conducted during soft sensor development. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Application of rock mechanics to cut-and-fill mining. Volume 1

Energy Technology Data Exchange (ETDEWEB)

1980-05-15

The conference on application of rock mechanics to cut-and-fill mining was held June 1-3, 1980, at the University of Luleaa, Sweden. The conference began with reviews of the application of rock mechanics to mining and back filling in Australia, Canada and the USA. More particular papers involved mines in Sweden, Italy, Australia (pre reinforcement of walls with steel cables cemented in) and at the Con Mine in Canada. Two papers involved backfill material and specifications. Eight papers involved the use of the mathematical models for calculating the stresses developed in the rock mass by computer calculations and therefore, the probable stability. Such calculations are particularly necessary in deep mines. Papers of general interest were entered individually into EDB. (LTN)

Synthesis of H/Bentonite and Ni/Al2O3-bentonite and its application to produce biogasoline from nyamplung seed (Calophyllum inophillum Linn) oil by catalytic hydrocracking

Science.gov (United States)

Marini, A. T.; Wijaya, K.; Sasongko, N. A.

2018-03-01

Hydrocracking process of Nyamplung (Calophyllum inophillum Linn) seed oil to produce biogasoline using H/bentonite and Ni/Al2O3-bentonite that pillared by Al2O3 as catalyst had been conducted. Bentonite was activated by acidification using HF 1% and H2SO4 0.5 M. Ni metal was impregnated into bentonite with two steps reaction; therewas intercalation with Al2O3kegging ion and Ni metal impregnation using NiCl2 metal salt. Catalysts were characterized by infrared spectrophotometer (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), BET, TEM and ammonia adsorption. Hydrocracking reaction was variated by Ni/Al2O3-bentonite and H/bentonite with ratio catalyst/oil 1:100. Biocrude was prepared by extraction by using ethanol 96%. Hydrocracking oil products were further analyzed by GC-MS. The results show that the acidity of bentonite by activation using HF 1% and H2SO4 0.5 M has been increased from 62.58 to 64.62 mmol/g. Impregnation process also increased the acidity of bentonite from 62.58 to 64.89 mmol/g. Activation using HF 1% and H2SO4 0.5 M, intercalation by Al2O3 and impregnation by Ni metal were increasing the crystallinity, surface area, total volume pore and average pore size of bentonite. These techniques were also causeddealumination of bentonite. The hydrocracking process successfully synthesized hydrocarbons with a number of carbon chain between C5-C20 which include bio-gasoline group compounds. Moreover, catalytic processes by H/bentonite and Ni/Al2O3-bentonite also successfully produced 39.83% and 60.37% of biogasoline yields, respectively.

Cements in Radioactive Waste Disposal

International Nuclear Information System (INIS)

Glasser, F.P.

2013-01-01

nature of Portland cement is explained. Portland cement is the most widely used cement type and benefits from technology transfer from civil engineering research; also of the more than 150 years of experience of its durability and performance in a range of service environments. The origin of the chemical binding potential of cement arises from a combination of mechanisms: chemisorption on cement solids, incorporation by solid solution in cement solids and, at higher concentrations, precipitation of a solubility-limiting phase or phases in a calcium rich, high pH environment. These favourable potentials, especially pH conditioning, are, as noted, essentially sacrificial: cement must dissolve or react to maintain these conditions in the course of its service life. However the immobilisation potential will also change with time, even in isolation, because cement minerals undergo internal aging and slow reaction with other materials in the near field. Much research has been conducted, often on an empirical basis, leading to the characterisation of these potentials and of their time dependence. Yet the picture which emerges is incomplete and of variable quality. New research is described which, it is expected, will lead to a more scientific basis for the extrapolation of present-day cement performance into the future. The high pH of Portland cement matrices has advantages but also, disadvantages. For example, Portland cement gives excellent protection against corrosion to embedded steel but, on the other hand, it corrodes electropositive metals with evolution of hydrogen. Formation of a high pH 'plume' may also spread from the concrete to the near field, degrading other barriers such as bentonite and affecting the sorptive potential of the near field for radionuclides. These considerations have led to the search for alternative lower pH cements which are less alkaline than Portland cement. A description of some common types is given. However alternative choices present a

Cements in Radioactive Waste Disposal

Energy Technology Data Exchange (ETDEWEB)

Glasser, F. P. [University of Aberdeen, Scotland (United Kingdom)

2013-09-15

nature of Portland cement is explained. Portland cement is the most widely used cement type and benefits from technology transfer from civil engineering research; also of the more than 150 years of experience of its durability and performance in a range of service environments. The origin of the chemical binding potential of cement arises from a combination of mechanisms: chemisorption on cement solids, incorporation by solid solution in cement solids and, at higher concentrations, precipitation of a solubility-limiting phase or phases in a calcium rich, high pH environment. These favourable potentials, especially pH conditioning, are, as noted, essentially sacrificial: cement must dissolve or react to maintain these conditions in the course of its service life. However the immobilisation potential will also change with time, even in isolation, because cement minerals undergo internal aging and slow reaction with other materials in the near field. Much research has been conducted, often on an empirical basis, leading to the characterisation of these potentials and of their time dependence. Yet the picture which emerges is incomplete and of variable quality. New research is described which, it is expected, will lead to a more scientific basis for the extrapolation of present-day cement performance into the future. The high pH of Portland cement matrices has advantages but also, disadvantages. For example, Portland cement gives excellent protection against corrosion to embedded steel but, on the other hand, it corrodes electropositive metals with evolution of hydrogen. Formation of a high pH 'plume' may also spread from the concrete to the near field, degrading other barriers such as bentonite and affecting the sorptive potential of the near field for radionuclides. These considerations have led to the search for alternative lower pH cements which are less alkaline than Portland cement. A description of some common types is given. However alternative choices present a

Physical Activity Questionnaire for children and adolescents: English norms and cut-off points.

Science.gov (United States)

Voss, Christine; Ogunleye, Ayodele A; Sandercock, Gavin R H

2013-08-01

The Physical Activity Questionnaire for Children and Adolescents (PAQ-C/-A) provides general estimates of physical activity levels. Following recent expert recommendations for using the PAQ for population surveillance, the aim of this paper was twofold: first, to describe normative PAQ data for English youth; and second, to determine a criterion-referenced PAQ-score cut-off point. Participants (n = 7226, 53% boys, 10-15 years) completed an anglicized version of the PAQ. Peak oxygen uptake (VO2peak ) was predicted from PACER lap count according to latest FITNESSGRAM standards and categorized into "at-risk" and "no-risk" for metabolic syndrome. ROC curves were drawn for each age-sex group to identify PAQ scores, which categorized youth into "sufficiently active" versus "low-active" groups, using cardiorespiratory fitness as the criterion-referenced standard. PAQ scores were higher in boys than in girls and declined with age. Mean PAQ score was a significant, albeit relatively weak (area under the curve PAQ scores of ≥2.9 for boys and ≥2.7 for girls were identified as cut-off points, although it may be more appropriate to use lower, age-specific PAQ scores for girls of 13, 14 and 15 years (2.6, 2.4, 2.3, respectively). The normative and criterion-referenced PAQ values may be used to standardize and categorize PAQ scores in future youth population studies. © 2013 The Authors. Pediatrics International © 2013 Japan Pediatric Society.

The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens.

Directory of Open Access Journals (Sweden)

Isabel E Moller

Full Text Available The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus degrades cellulose have hampered our understanding of the selection forces that induced large scale herbivory and of the ensuing ecological footprint of these ants. Here we use a recently established technique, based on polysaccharide microarrays probed with antibodies and carbohydrate binding modules, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste material that the ants remove from their fungus garden. These results demonstrate that biomass entering leaf-cutting ant fungus gardens is only partially utilized and explain why disproportionally large amounts of plant material are needed to sustain colony growth. They also explain why substantial communities of microbial and invertebrate symbionts have evolved associations with the dump material from leaf-cutting ant nests, to exploit decomposition niches that the ant garden-fungus does not utilize. Our approach thus provides detailed insight into the nutritional benefits and shortcomings associated with fungus-farming in ants.

Hydraulic Conductivity of Residual Soil-Cement Mix

Science.gov (United States)

Govindasamy, P.; Taha, M. R.

2016-07-01

In Malaysia, although there are several researches on engineering properties of residual soils, however study on the hydraulic conductivity properties of metasedimentary residual soils is still lacking. Construction of containment walls like slurry wall techniques can be achieved with hydraulic conductivity of approximately 5 x 10-7cm/sec. The objectives of the study were to determine the physical properties of metasedimentary residual soils and to determine the influence of 1%, 3%, 5% and 10% of cement on hydraulic conductivity parameters. The coefficient of hydraulic conductivity of the soil naturally and soil-cement mixtures were determined by using the falling head test. According to the test, the hydraulic conductivity of the original soil was 4.16 x 10-8 m/s. The value decreases to 3.89 x 10-8 m/s, 2.78 x 10-8 m/s then 6.83 x 10-9 m/s with the addition of 1%, 3% and 5% of cement additives, respectively. During the hydration process, cement hydrates is formed followed by the increase in pH value and Ca(OH)2 which will alter the modification of pores size and distribution. When the quantity of cement increases, the pores size decrease. But, the addition of 10% cement gives an increased hydraulic conductivity value to 2.78 x 10-8 m/s. With 10%, the pore size increase might due to flocculation and agglomeration reaction. The generated hydraulic conductivity values will indirectly become a guide in the preliminary soil cement stabilization to modify the properties of the soil to become more like the properties of a soft rock.1. Introduction

Sorption behavior of cesium onto bentonite colloid

International Nuclear Information System (INIS)

Iijima, Kazuki; Masuda, Tsuguya; Tomura, Tsutomu

2004-01-01

It is considered that bentonite colloid might be generated from bentonite which will be used as buffer material in geological disposal system, and can facilitate the migration of radionuclides by means of sorption. In order to examine this characteristic, sorption and desorption experiments of Cs onto bentonite colloid were carried out to obtain its distribution coefficient (Kd) and information on the reversibility of its sorption. In addition, particle size distribution and shape of colloid were investigated and their effect on the sorption behavior was discussed. Kds for Cs were around 20 m 3 /kg for sorption and 30 m 3 /kg for desorption, in which sorbed Cs was desorbed by 8.4x10 -4 mol/l of NaCl solution. These values did not show any dependencies on Cs concentration and duration of sorption and desorption. The first 20% of sorbed Cs was desorbed reversibly at least. Most of colloidal particles were larger than 200 nm and TEM micrographs showed they had only several sheets of the clay crystal. Obtained Kds for colloidal bentonite were larger than those for powdered bentonite. This can be caused by difference of competing ions in the solution, characteristics of contained smectite, or sorption site density. (author)

A cautionary note about the cross-national and clinical validity of cut-off points for the Maslach Burnout Inventory.

Science.gov (United States)

Schaufeli, W B; Van Dierendonck, D

1995-06-01

In the present study, burnout scores of three samples, as measured with the Maslach Burnout Inventory, were compared: (1) the normative American sample from the test-manual (N = 10,067), (2) the normative Dutch sample (N = 3,892), and (3) a Dutch outpatient sample (N = 142). Generally, the highest burnout scores were found for the outpatient sample, followed by the American and Dutch normative samples, respectively. Slightly different patterns were noted for each of the three components. Probably sampling bias, i.e., the healthy worker effect, or cultural value patterns, i.e., femininity versus masculinity, might be responsible for the results. It is concluded that extreme caution is required when cut-off points are used to classify individuals by burnout scores; only nation-specific and clinically derived cut-off points should be employed.

Cerebrospinal fluid neopterin analysis in neuropediatric patients: establishment of a new cut off-value for the identification of inflammatory-immune mediated processes.

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Marta Molero-Luis

Full Text Available OBJECTIVE: A high level of cerebrospinal fluid (CSF neopterin is a marker of central nervous system inflammatory-immune mediated processes. We aimed to assess data from 606 neuropediatric patients, describing the clinical and biochemical features of those neurological disorders presenting CSF neopterin values above a new cut-off value that was defined in our laboratory. METHODS: To establish the new CSF neopterin cut-off value, we studied two groups of patients: Group 1 comprised 68 patients with meningoencephalitis, and Group 2 comprised 52 children with a confirmed peripheral infection and no central nervous system involvement. We studied 606 CSF samples from neuropediatric patients who were classified into 3 groups: genetic diagnosis (A, acquired/unknown etiologic neurologic diseases (B and inflammatory-immune mediated processes (C. RESULTS: The CSF neopterin cut-off value was 61 nmol/L. Out of 606 cases, 56 presented a CSF neopterin level above this value. Group C had significantly higher CSF neopterin, protein and leukocyte values than the other groups. Sixteen of twenty-three patients in this group had a CSF neopterin level above the cut-off, whereas three and seven patients presented increased leukocyte and protein values, respectively. A significant association was found among CSF neopterin, proteins and leukocytes in the 606 patients. White matter disturbances were associated with high CSF neopterin concentrations. CONCLUSIONS: Although children with inflammatory-immune mediated processes presented higher CSF neopterin values, patients with other neurological disorders also showed increased CSF neopterin concentrations. These results stress the importance of CSF neopterin analysis for the identification of inflammatory-immune mediated processes.

TECHNOLOGY OF REVERSE-BLAST CORROSION CLEANING OF STEEL SHEETS PRIOR TO LASER CUTTING

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A. N. Zguk

2017-01-01

Full Text Available Quality of surface cleaning against corrosion influences on efficiency in realization of a number of technological processes. While using bentonite clays in power fluid reverse-blast cleaning ensures formation of anticorrosion protective coating with light absorbing properties on the cleaned surface and prevents formation of the repeated corrosion. The paper presents results of the investigations pertaining to influence of reverse-blast cleaning parameters of steel sheets on quality of the cleaned surface prior to laser cutting. Processing conditions, applied compositions of power fluid and also properties of the protective film coatings on the cleaned surface have been given in the paper. The paper considers topography, morphology and chemical composition of the given coating while applying complex metal micrographic, X-ray diffraction and electronic and microscopic investigations. A complex of laser cutting (refer to gas lasers with output continuous capacity of 2.5/4.0 kW has been applied for experimental works to evaluate influence of the formed surface quality on efficiency of laser cutting process. Specimens having dimension 120×120 mm, made of steel Ст3пс, with thickness from 3 to 10 mm have been prepared for the experiments. An analysis has shown that the application of reverse-blast cleaning ensures higher speed in laser cutting by a mean of 10–20 %. The investigations have made it possible to determine optimum cleaning modes: distance from a nozzle to the surface to be cleaned, jet velocity, pressure. It has been revealed that after drying of the specimens processed by power fluid based on water with concentrations of bentonite clay and calcined soda a protective film coating with thickness of some 5–7 µm has been formed on the whole cleaned specimen surfaces. Chemical base of the coating has been formed by the elements which are included in the composition of bentonite clay being the basic component of the power fluid. 

Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing.

Science.gov (United States)

Boonstra, Anne M; Stewart, Roy E; Köke, Albère J A; Oosterwijk, René F A; Swaan, Jeannette L; Schreurs, Karlein M G; Schiphorst Preuper, Henrica R

2016-01-01

Objectives: The 0-10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate, and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients' catastrophizing and their sex on these cut-off points. Methods: 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion: The study showed that NRS scores ≤ 5 correspond to mild, scores of 6-7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90% of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤ 3 correspond to mild, scores of 4-6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low

The cut-off point of dual energy X-ray and laser of calcaneus osteoporosis diagnosis in postmenopausal women

International Nuclear Information System (INIS)

Salimzadeh, A.; Forough, B.; Olia, B.; Alishiri, G. H.; Ghasemzadeh, A.

2005-01-01

Dual X-Ray Absorptiometry is a method which can extensively be used for bone mineral densitometry . Another more recent method is dual energy X-ray and laser, which associate with dual X ray absorptiometry, assisted by laser measure heel thickness. In this study the cut off points for dual energy X-ray and laser of calcaneus in the diagnosis of osteoporosis in different bone regions in postmenopausal women had been determined. Materials and Methods: In 268 postmenopausal women, BMD of the spinal and femoral regions was measured by DM, and the value for the calcaneous was measured by dual energy X-ray and laser. The agreement of the two methods in the diagnosis of osteoporosis and optimal cut-off point for dual energy X-ray and laser in defining osteoporosis was obtained. What obtained was the agreement of the two methods in the diagnosis of osteoporosis, as well as the optimal cut-off point for dual energy X-ray and laser in defining osteoporosis. Results: Dual X-Ray Absorptiometry showed osteoporosis in 40.7% of cases with 35.2% in L2-L4, 16.2% in the femoral neck, and 11.7% for the femoral total region. The dual energy X-ray and laser found osteoporosis, considering -2.5 SD as a threshold, in 26.1% of cases. Agreement of the two methods in the diagnosis of osteoporosis (Kappa score) was 0.443 for the lumbar region, 0.464 for the neck, and, 0.421 for total femur regions (all P values were significant). Using Receiver Operating Characteristic curves, it was found that a T-score of -2.1, -2.6 and -2.4 as the optimal cut-off point of dual energy X-ray and laser in the diagnosis of osteoporosis in the lumbar spine, the neck and total region of femur, respectively. Conclusion: The results of this study showed a moderate agreement between the two methods in the diagnosis of osteoporosis. It seems that the dual energy X-ray and laser cannot be used as a substitute for the DM method, but it can be used as a screening method to find (to diagnose) osteoporosis

Modelling interaction of deep groundwaters with bentonite and radionuclide speciation

International Nuclear Information System (INIS)

Wanner, H.

1986-04-01

In the safety analysis recently reported for a potential Swiss high-level waste repository, radionuclide speciation and solubility limits are calculated for expected granitic groundwater conditions. This report describes a thermodynamic model which is used to estimate the chemical composition of the pore water in compacted sodium bentonite. The model is based on available experimental data and describes the basic reactions between bentonite and groundwater by an ion-exchange model for sodium, potassium, magnesium, and calcium. The model assumes equilibrium with calcite as long as sufficient carbonates remain in the bentonite, as well as quartz saturation. The long-term situation is modelled by the assumption that the near-field of a deep repository behaves like a mixing tank. It is found that sodium bentonite will slowly be converted to calcium bentonite. The modelled composition of the pore water of compacted sodium bentonite is used to estimate radionuclide solubilities in the near-field of a deep repository. The elements considered are: uranium, neptunium, plutonium, thorium, americium, and technetium. The redox potential in the near-field is assumed to be controlled by the corrosion products of the iron canister. Except for uranium and neptunium, radionuclide solubilities turn out to be lower under the modelled near-field conditions than in the groundwater of the surrounding granitic host rock. Uranium and neptunium solubility might be higher by orders of magnitude in the near-field than in the far-field. From the chemical point of view, calcium bentonite seems to be more stable than sodium bentonite in the presence of Swiss Reference Groundwater. The use of calcium bentonite instead of sodium bentonite will improve the reliability in the prediction of source terms for radionuclide transport in the geosphere. (author)

Water uptake and stress development in bentonites and bentonite-sand buffer materials

International Nuclear Information System (INIS)

Dixon, D.A.; Wan, A.W-L.; Gray, M.N.; Miller, S.H.

1996-10-01

The development of swelling pressure and the transfer of pore water pressures through dense bentonite and bentonite-sand materials are examined in this report. This report focuses on the swelling pressure and total pressure developed in initially unsaturated specimens allowed access to free water on one end. The bentonite in this wetted region rapidly develops its full swelling pressure and this pressure is transferred upwards through the specimen. Hence, the bentonite plug will exert a pressure approximately equivalent to the swelling pressure even though only a small region of the plug is actually saturated. A number of specimens were tested with total pressure sensors mounted normal and parallel to the axis of compaction. Lateral pressures developed long before the wetting front reached sensor locations, suggesting stress transfer through the unsaturated portions of these specimens. On achieving saturation, specimens were found to have similar swelling pressures both normal to and parallel to the axis of compaction. This indicates that there is little or no specimen anisotropy induced by the compaction process. Tests were conducted on specimens allowed only to take on a limited quantity of water and it was found that density anisotropy was induced as the result of the swelling pressures generated by the buffer. The wetted skin of buffer developed a considerable pressure and compressed a region of buffer immediately above the wetted region. The results suggest that the buffer material placed in a disposal vault will rapidly develop and transfer swelling pressures as a result of the saturation of a limited region or 'skin' within the emplacement site. The total pressure ultimately present on the container surface should be the sum of the swelling and hydraulic components. (author). 14 refs., 4 tabs., 8 figs

India and the fissile material cut-off treaty: policy options

International Nuclear Information System (INIS)

Nayan, Rajiv

2011-01-01

The international community inside and outside the Conference of Disarmament is underscoring the need for concluding a fissile material cut-off treaty (FMCT). The Indian government, for a long period, has been sponsoring the idea. Notwithstanding the international stagnation, the issue has been instigating periodic debate in India on the Indian approach. The periodic revival of the issue requires that India revisit its policy on fissile material production as well as its approach towards a possible EVICT. This article examines the question: should India's approach to conclude an FMCT be within the UN institutional framework? The new international reality is pushing for a new context, new realignments and a fresh outlook for an FMCT. India should take its own time to support conclusion of an FMCT so that its national interests and security are not adversely affected. (author)

Sequential use of bentonites and solar photocatalysis to treat winery wastewater.

Science.gov (United States)

Rodríguez, Eva; Márquez, Gracia; Carpintero, Juan Carlos; Beltrán, Fernando J; Alvarez, Pedro

2008-12-24

The sequential use of low-cost adsorbent bentonites and solar photocatalysis to treat winery wastewater has been studied. Three commercial sodium-bentonites (MB-M, MB-G, and MB-P) and one calcium-bentonite (Bengel) were characterized and used in this study. These clay materials were useful to totally remove turbidity (90-100%) and, to a lesser extent, color, polyphenols (PPh), and soluble chemical oxygen demand (CODS) from winery wastewater. Both surface area and cation exchange capacity (CEC) of bentonite had a positive impact on treatment efficiency. The effect of pH on turbidity removal by bentonites was studied in the 3.5-12 pH range. The bentonites were capable of greatly removing turbidity from winery wastewater at pH 3.5-5.5, but removal efficiency decreased with pH increase beyond this range. Settling characteristics (i.e., sludge volume index (SVI) and settling rate) of bentonites were also studied. Best settling properties were observed for bentonite doses around 0.5 g/L. The reuse of bentonite for winery wastewater treatment was found not to be advisable as the turbidity and PPh removal efficiencies decreased with successive uses. The resulting wastewater after bentonite treatment was exposed to solar radiation at oxic conditions in the presence of Fe(III) and Fe(III)/H2O2 catalysts. Significant reductions of COD, total organic carbon (TOC), and PPh were achieved by these solar photocatalytic processes.

High harmonic generation at the tunneling ionization of atoms by intense laser radiation near the classical cut-off

Science.gov (United States)

Gets, A. V.; Krainov, V. P.

2018-01-01

The yield of spontaneous photons at the tunneling ionization of atoms by intense low-frequency laser radiation near the classical cut-off is estimated analytically by using the three-step model. The Bell-shaped dependence in the universal photon spectrum is explained qualitatively.

The Potential of Established Fitness Cut-off Points for Monitoring Women with Fibromyalgia : The al-Ándalus Project

NARCIS (Netherlands)

Castro-Piñero, José; Aparicio, Virginia A; Estévez-López, Fernando; Álvarez-Gallardo, Inmaculada C; Borges-Cosic, Milkana; Soriano-Maldonado, Alberto; Delgado-Fernández, Manuel; Segura-Jiménez, Víctor

2017-01-01

The aim of the present study was to determinate whether fitness cut-off points discriminate the severity of major fibromyalgia symptoms and health-related quality of life. Additionally, we investigated which American Colleague of Rheumatology (ACR) fibromyalgia criteria (1990 vs. modified 2010)

Interannual rainfall variability over the Cape south coast of South Africa linked to cut-off low associated rainfall

CSIR Research Space (South Africa)

Engelbrecht, CJ

2014-10-01

Full Text Available The influence of cut-off low (COL) associated rainfall on interannual rainfall variability over the Cape south coast region of South Africa for the period 1979-2011 is investigated. COLs are objectively identified and tracked on daily average 500 h...

Corrosion of high-level radioactive waste iron-canisters in contact with bentonite

Energy Technology Data Exchange (ETDEWEB)

Kaufhold, Stephan, E-mail: s.kaufhold@bgr.de [BGR, Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover (Germany); Hassel, Achim Walter [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, D-40237 Düsseldorf (Germany); Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Sanders, Daniel [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, D-40237 Düsseldorf (Germany); Dohrmann, Reiner [BGR, Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover (Germany); LBEG, Landesamt für Bergbau, Energie und Geologie, Stilleweg 2, D-30655 Hannover (Germany)

2015-03-21

Graphical abstract: Corrosion at the bentonite iron interface proceeds unaerobically with formation of an 1:1 Fe silicate mineral. A series of exposure tests with different types of bentonites showed that Na–bentonites are slightly less corrosive than Ca–bentonites and highly charges smectites are less corrosive compared to low charged ones. The formation of a patina was observed in some cases and has to be investigated further. - Highlights: • At the iron bentonite interface a 1:1 Fe layer silicate forms upon corrosion. • A series of iron–bentonite corrosion products showed slightly less corrosion for Na-rich and high-charged bentonites. • In some tests the formation of a patina was observed consisting of Fe–silicate, which has to be investigated further. - Abstract: Several countries favor the encapsulation of high-level radioactive waste (HLRW) in iron or steel canisters surrounded by highly compacted bentonite. In the present study the corrosion of iron in contact with different bentonites was investigated. The corrosion product was a 1:1 Fe layer silicate already described in literature (sometimes referred to as berthierine). Seven exposition test series (60 °C, 5 months) showed slightly less corrosion for the Na–bentonites compared to the Ca–bentonites. Two independent exposition tests with iron pellets and 38 different bentonites clearly proved the role of the layer charge density of the swelling clay minerals (smectites). Bentonites with high charged smectites are less corrosive than bentonites dominated by low charged ones. The type of counterion is additionally important because it determines the density of the gel and hence the solid/liquid ratio at the contact to the canister. The present study proves that the integrity of the multibarrier-system is seriously affected by the choice of the bentonite buffer encasing the metal canisters in most of the concepts. In some tests the formation of a patina was observed consisting of Fe�

Exploration of the optimal diameter cut-off value in patients with nonfunctional adrenal tumor suitable for surgery

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Dan-dan LIU

2016-12-01

Full Text Available Objective 　To analyze the pathology of the patients with nonfunctional adrenal tumor (NFA, and explore the optimal diameter cut-off value. Methods 　The clinical data of 243 patients with NFA, evaluated in the Department of Endocrinology and operated in the Department of Urology of General Hospital of Chinese PLA from Feb. 1996 to Jan. 2016, were collected. The patients were divided into two groups according to pathology: those in real demand of surgery were classified to the surgery-need group (n=57, while the others were categorized as the surgery-unwanted group (n=186. The general situation, pathological type and tumor diameter of the two groups and the factors affecting the surgery were analyzed, and the ROC curve was used to explore the optimal surgery cut-off value, which represents the maximum value of the sum of sensitivity and specificity. Results 　Of the 57 patients in surgery-need group (27 males and 30 females, the lesions were on the right in 31 cases, on the left in 25 cases, and on bilateral sides in 1 case; the median of lesion diameter was 4.5cm, and the average age was 41.5±12.1 years old. Of the 186 patients in surgery-unwanted group (87 males and 99 females, the lesions were on the right in 99 cases, on the left in 86 cases, and on bilateral sides in 1 case; the median of lesion diameter was 3.0cm, and the average age was 50.6±10.9 years old. Logistic regression revealed that lesion diameter might be a risk factor (OR=1.340, 95%CI 1.266-1.418, P=0.000 and age be a protective factor (OR=0.942, 95%CI 0.929-0.955, P=0.000 for real demand of surgery. The area under the ROC curve (AUC of lesion diameter was 0.757(95%CI 0.681-0.833. The optimal cut-off value was 4.1cm (sensitivity 60.7% and specificity 83.0%. Conclusions 　Younger patients with bigger lesion diameter may have greater possibility for surgery. The optimal surgery cut-off value of the lesion diameter is 4.1cm. DOI: 10.11855/j.issn.0577-7402.2016.11.11

Small-scale bentonite injection test on rock

International Nuclear Information System (INIS)

Pusch, R.

1978-03-01

When radiactive waste is disposed a sealing of the rock is very valuable since it reduces the rate of water percolation and diffusion. In an earlier report injection of bentonite gels by means of over-pressure and subsequent electrophoresis has been suggested. The present report describes a rock test series where bentonite injection was applied. For the test an approximately cubical block of about 1 m 3 was selected. The rock type was diorite with a fairly high frequency of quartz denses. The block was kept in a basin during the test in order to maintain the water saturation. Holes were bored in the block. A bentonite slurry with 1000 percent water content was injected. It was shown that the bentonite had a sealing effect but the depth of extrusion into rock joints was not large because of gelation. Electro-Kinetic injection of montmorillonite was found to be a more promising technique for rock lightening

Pemanfaatan Bentonite sebagai Media Pembumian Elektroda Batang

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Winanda Riga Tamma

2017-03-01

Full Text Available Sistem pentanahan merupakan suatu sistem yang bertujuan untuk mengamankan sistem tenaga listrik dari gangguan ke tanah maupun gangguan hubung singkat. Pada sistem pentanahan yang baik, resistansi pentanahan harus bernilai dibawah lima ohm. Resistansi pentanahan bergantung pada berbagai aspek antara lain yaitu struktur tanah, kelembapan tanah, dan kandungan yang ada dalam tanah itu sendiri. Dalam pengujian pada penelitian ini akan dilakukan perbaikan pada tanah dengan mencampurkan bentonite ke dalam tanah sebagai media pentanahan. Pencampuran bentonite bertujuan agar mendapatkan nilai resistansi pentanahan yang baik sesuai dengan standar sistem pentanahan. Pengujian dilakukan menggunakan elektroda batang dan alat earth resistance tester dengan metode tiga titik dimana elektroda utama atau elektroda pengukuran diberikan treatment sesuai dengan kondisi yang telah ditentukan. Diharapkan pada pengujian ini akan diketahui dampak dari bentonite terhadap penurunan nilai resistansi pentanahan. Hasil pengujian menunjukkan bahwa dengan mencampurkan bentonite pada media pentanahan, resistansi pentanahan menjadi lebih baik. Meskipun tidak terlalu signifikan, rata-rata penurunan dari setiap masing-masing treatment adalah sebesar 2 ohm.

Break-apart interphase fluorescence in situ hybridization assay in papillary thyroid carcinoma: on the road to optimizing the cut-off level for RET/PTC rearrangements.

Science.gov (United States)

Colato, Chiara; Vicentini, Caterina; Cantara, Silvia; Pedron, Serena; Brazzarola, Paolo; Marchetti, Ivo; Di Coscio, Giancarlo; Chilosi, Marco; Brunelli, Matteo; Pacini, Furio; Ferdeghini, Marco

2015-05-01

Chromosomal rearrangements of the RET proto-oncogene is one of the most common molecular events in papillary thyroid carcinoma (PTC). However, their pathogenic role and clinical significance are still debated. This study aimed to investigate the prevalence of RET/PTC rearrangement in a cohort of BRAF WT PTCs by fluorescence in situ hybridization (FISH) and to search a reliable cut-off level in order to distinguish clonal or non-clonal RET changes. Forty BRAF WT PTCs were analyzed by FISH for RET rearrangements. As controls, six BRAFV600E mutated PTCs, 13 follicular adenomas (FA), and ten normal thyroid parenchyma were also analyzed. We performed FISH analysis on formalin-fixed, paraffin-embedded tissue using a commercially available RET break-apart probe. A cut-off level equivalent to 10.2% of aberrant cells was accepted as significant. To validate FISH results, we analyzed the study cohort by qRT-PCR. Split RET signals above the cut-off level were observed in 25% (10/40) of PTCs, harboring a percentage of positive cells ranging from 12 to 50%, and in one spontaneous FA (1/13, 7.7%). Overall, the data obtained by FISH matched well with qRT-PCR results. Challenging findings were observed in five cases showing a frequency of rearrangement very close to the cut-off. FISH approach represents a powerful tool to estimate the ratio between broken and non-broken RET tumor cells. Establishing a precise FISH cut-off may be useful in the interpretation of the presence of RET rearrangement, primarily when this strategy is used for cytological evaluation or for targeted therapy. © 2015 European Society of Endocrinology.

Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions. Part 2. Effect of type of alkaline solution on permeability of compacted bentonite-sand mixture

International Nuclear Information System (INIS)

Yokoyama, Shingo; Nakamura, Kunihiko; Tanaka, Yukihisa; Hironaga, Michihiko

2011-01-01

Permeability tests were carried out using compacted bentonite-sand mixture with initial dry density of 1.55 Mg/m 3 and alkaline solutions at 50degC for about two years to estimate the alteration behavior and the change in the permeability. Bentonite-sand mixtures which contain bentonites of 15wt% were made using Na-bentonite or Ca-exchanged bentonite. 0.3M-NaOH solution with pH 13.3 and 5mM-Ca(OH) 2 solution with pH 12.0 were used to the permeability tests of Na-bentonite-sand mixture and of Ca-exchanged bentonite-sand mixture, respectively. In the case of the permeability test conducted using NaOH solution, montmorillonite and other associated minerals were dissolved, and consequently, the dry density and effective montmorillonite density of Na-bentonite-sand mixture were decreased. Furthermore, the mineralogical feature of montmorillonite was changed (i.e. beidellitization and an increase in the layer charge). The permeability of Na-bentonite-sand mixture was increased 5.6 times by the end of permeability test as a result of above alteration. In the case of the permeability test conducted using Ca(OH) 2 solution, montmorillonite and other associated minerals were dissolved, and calcium silicate hydrate (C-S-H) was precipitated. Consequently, the dry density of Ca-exchanged bentonite-sand mixture was increased, while the effective montmorillonite density was decreased. The mineralogical feature of montmorillonite was changed (i.e. beidellitization and an increase in the layer charge). The permeability of Ca-exchange bentonite-sand mixture was decreased by more than two orders of magnitude due to fill the pore of Ca-exchange bentonite-sand mixture by the precipitation of C-S-H. From above results, the type of alkaline solution affects the mineralogical alteration behavior of the compacted bentonite-sand mixture, and consequently, affects the changing trend of permeability. In conclusion, it is important not only to consider the dissolution of montmorillonite, but

Simulation of bentonite colloid migration through granite

International Nuclear Information System (INIS)

Rosicka, Dana; Hokr, Milan

2012-01-01

Document available in extended abstract form only. Full text of publication follows: Colloidal bentonite particles generate at the interface of buffer and host rock in spent nuclear fuel repository due to an erosion process and migrate through granite by the water flow. Stability of these colloids and their migration possibilities have been studied on account of radionuclide transport possibility as colloid could carry adsorbed radionuclides in groundwater through granite. That is why a simulation of bentonite colloid migration in the surrounding of a repository might be requested. According to chemical condition as ionic strength and pH, the colloidal particles coagulate into clusters and that influence the migration of particles. The coagulation kinetics of natural bentonite colloids were experimentally studied in many articles, for example by light scattering techniques. We created a model of coagulation of bentonite colloids and simulation of a chosen experiment with use of the multicomponent reactive transport equation. The coagulation model describes clustering of particles due to attractive van der Waals forces as result of collision of particles due to heat fluctuation and different velocity of particles during sedimentation and velocity gradient of water flow. Next, the model includes influence of repulsive electrostatic forces among colloidal particles leading to stability of particles provided high surface charge of colloids. In the model, each group of clusters is transported as one solution component and the kinetics of coagulation are implemented as reactions between the components: a shift of particles among groups of particles with similar migration properties, according to size of the clusters of colloids. The simulation of migration of bentonite colloid through granite using the coagulation model was calibrated according to experiment results. On the basis of the simulation, one can estimate the basic processes that occur during bentonite colloid

Diffusion in crushed rock and in bentonite clay

International Nuclear Information System (INIS)

Olin, M.

1994-04-01

Diffusion theories for porous media with sorption are reviewed to serve as a basis for considering diffusion in simple systems like sand of crushed rock. A Fickian diffusion and linear sorption model is solved both by analytical Laplance transform and Green's function methods and by numerical methods, and then applied to small-scale experiments for Finnish low- and medium-level operating waste repositories. The main properties of bentonite are reviewed. The hydraulic conductivity of compacted bentonite is so low that the major transport mechanism is diffusion. A Fickian diffusion and linear sorption model is applied to bentonite. The main component of bentonite, montmorillonite, has a high ion-exchange capacity and thus, transport in bentonite consists of interactive chemical and diffusion phenomena. A chemical equilibrium model, CHEQ, is developed for ion-exchange reactions in bentonite water systems. CHEQ is applied to some bentonite experiments with success, especially for monovalent ions. The fitted log-binding constants for sodium exchange with potassium, magnesium, and calcium were 0.27, 1.50, and 2.10, respectively. A coupled chemical and diffusion model, CHEQDIFF, is developed to take account of diffusion in pore water, surface diffusion and ion-exchange reactions. The model is applied to the same experiments as CHEQ, and validation is partly successful. In the diffusion case, the above-mentioned values for binding constants are used. The apparent diffusion (both anions and cations) and surface diffusion (only for cations) constants used are 3.0*10 -11 m 2 /s and 6.0*10 -12 m 2 /s, respectively, but these values are questionable, as experimental results good enough for fitting are not available. (orig.). (74 refs., 27 figs., 12 tabs.)

Preparation and Fatigue Properties of Functionally Graded Cemented Carbides

International Nuclear Information System (INIS)

Liu Yong; Liu Fengxiao; Liaw, Peter K.; He Yuehui

2008-01-01

Cemented carbides with a functionally graded structure have significantly improved mechanical properties and lifetimes in cutting, drilling and molding. In this work, WC-6 wt.% Co cemented carbides with three-layer graded structure (surface layer rich in WC, mid layer rich in Co and the inner part of the average composition) were prepared by carburizing pre-sintered η-phase-containing cemented carbides. The three-point bending fatigue tests based on the total-life approach were conducted on both WC-6wt%Co functionally graded cemented carbides (FGCC) and conventional WC-6wt%Co cemented carbides. The functionally graded cemented carbide shows a slightly higher fatigue limit (∼100 MPa) than the conventional ones under the present testing conditions. However, the fatigue crack nucleation behavior of FGCC is different from that of the conventional ones. The crack nucleates preferentially along the Co-gradient and perpendicular to the tension surface in FGCC, while parallel to the tension surface in conventional cemented carbides

Pore water chemistry of Rokle Bentonite (Czech Republic)

International Nuclear Information System (INIS)

Cervinka, R.; Vejsada, J.

2010-01-01

Document available in extended abstract form only. With inflowing the groundwater to Deep Geological Repository (DGR), the interaction of this water with engineering barrier materials will alter both, barrier materials and also the groundwater. One of the most important alterations represents the formation of bentonite pore water that will affect a number of important processes, e.g. corrosion of waste package materials, solubility of radionuclides, diffusion and sorption of radionuclides. The composition of bentonite pore water is influenced primarily by the composition of solid phase (bentonite), liquid phase (inflowing groundwater), the gaseous phase (partial pressure of CO 2 ), bentonite compaction and the rate of groundwater species diffusion through bentonite. Also following processes have to be taken into account: dissolution of admixtures present in the bentonite (particularly well soluble salts, e.g. KCl, NaCl, gypsum), ion exchange process and protonation and deprotonation of surface hydroxyl groups on clay minerals. Long-term stability of mineral phases and possible mineral transformation should not be neglected as well. In the Czech Republic, DGR concept takes local bentonite into account as material for both buffer and backfill. The candidate bentonite comes from the Rokle deposit (NW Bohemia) and represents complex mixture of (Ca,Mg)-Fe-rich montmorillonite, micas, kaolinite and other mineral admixtures (mainly Ca, Mg, Fe carbonates, feldspars and iron oxides). The mineralogical and chemical characteristics were published previously. This bentonite is different in composition and properties from worldwide studied Na-bentonite (e.g. MX-80, Volclay) or Na-Ca bentonite (e.g. Febex). This fact leads to the need of investigation of Rokle bentonite in greater detail to verify its suitability as a buffer and backfill in DGR. Presented task is focused on the study of pore water evolution. Our approach for this study consists in modeling the pore water using

Effective moments of inertia and spin cut off parameters in Hf isotopes

International Nuclear Information System (INIS)

Razavi, R.; Sharifzadeh, N.; Farahmand, M.R.

2011-01-01

In all statistical theories the nuclear level density is the most characteristic quantity and plays a major role in the study of nuclear structure. Most experimental data on nuclear level density have been analyzed with analytical functions of the level density. On the basis of statistical models, the effective moments of inertia and spin cut off parameters have been determined for 176 Hf, 178 Hf and 180 Hf nuclei from extensive and complete level schemes and neutron resonance densities in low excitation energy levels. Then, moments of inertia of these nuclei have been determined by nuclear rotational model. The results have been compared with their corresponding rigid body value

Impact of corrosion-derived iron on the bentonite buffer within the KBS-3H disposal concept. The Olkiluoto site as case study

Energy Technology Data Exchange (ETDEWEB)

Wersin, P. (Gruner AG, Basel (Switzerland)); Birgersson, M.; Olsson, S.; Karnland, O. (Clay Technology, Lund (Sweden)); Snellman, M. (Saanio and Riekkola Oy, Helsinki (Finland))

2007-12-15

Steel components are unstable in EBS (Engineered Barrier System) environments. They will corrode to fairly insoluble corrosion products, such as magnetite, and also react with the smectitic matrix of the bentonite buffer. In this study, the impact of reduced iron on the buffer's stability has been assessed within the framework of the KBS-H concept. Our work includes two parts. In the first part, available data from experimental and modelling studies have been compiled and interpreted. In the second part, a relatively simple geochemical modelling exercise on the iron-bentonite interaction in the current KBS-3H disposal system has been performed using Olkiluoto as test case. The iron in this case stems from the perforated supercontainer steel shell foreseen to be emplaced around the buffer material. The iron-bentonite interaction under reducing conditions may involve different processes including sorption, redox and dissolution / precipitation reactions, the details of which are not yet understood. One process to consider is the sorption of corrosion-derived Fe(II). This process is fast and leads to strong binding of Fe(II) at the smectite surface. Whether this sorption reaction is accompanied by a redox and surface precipitation reaction is presently not clear. A further process to consider under very reducing conditions is the reduction of structural Fe(III) in the clay which may destabilise the montmorillonite structure. The process of greatest relevance for the buffer's performance is montmorillonite transformation in contact with reduced iron. This process is very slow and experimentally difficult to investigate. Current data suggest that the transformation process may either lead to a Fe-rich smectite (e.g. saponite) or to a non-swelling clay (berthierine or chlorite). In addition, cementation due to precipitation of iron corrosion products or of SiO{sub 2} resulting from montmorillonite transformation may occur. Physical properties of the buffer may

Impact of corrosion-derived iron on the bentonite buffer within the KBS-3H disposal concept. The Olkiluoto site as case study

International Nuclear Information System (INIS)

Wersin, P.; Birgersson, M.; Olsson, S.; Karnland, O.; Snellman, M.

2007-12-01

Steel components are unstable in EBS (Engineered Barrier System) environments. They will corrode to fairly insoluble corrosion products, such as magnetite, and also react with the smectitic matrix of the bentonite buffer. In this study, the impact of reduced iron on the buffer's stability has been assessed within the framework of the KBS-H concept. Our work includes two parts. In the first part, available data from experimental and modelling studies have been compiled and interpreted. In the second part, a relatively simple geochemical modelling exercise on the iron-bentonite interaction in the current KBS-3H disposal system has been performed using Olkiluoto as test case. The iron in this case stems from the perforated supercontainer steel shell foreseen to be emplaced around the buffer material. The iron-bentonite interaction under reducing conditions may involve different processes including sorption, redox and dissolution / precipitation reactions, the details of which are not yet understood. One process to consider is the sorption of corrosion-derived Fe(II). This process is fast and leads to strong binding of Fe(II) at the smectite surface. Whether this sorption reaction is accompanied by a redox and surface precipitation reaction is presently not clear. A further process to consider under very reducing conditions is the reduction of structural Fe(III) in the clay which may destabilise the montmorillonite structure. The process of greatest relevance for the buffer's performance is montmorillonite transformation in contact with reduced iron. This process is very slow and experimentally difficult to investigate. Current data suggest that the transformation process may either lead to a Fe-rich smectite (e.g. saponite) or to a non-swelling clay (berthierine or chlorite). In addition, cementation due to precipitation of iron corrosion products or of SiO 2 resulting from montmorillonite transformation may occur. Physical properties of the buffer may in principle be

Cut-off scores of a brief neuropsychological battery (NBACE for Spanish individual adults older than 44 years old.

Directory of Open Access Journals (Sweden)

Montserrat Alegret

Full Text Available The neuropsychological battery used in Fundació ACE (NBACE is a relatively brief, and easy to administer, test battery that was designed to detect cognitive impairment in the adulthood. The NBACE includes measures of cognitive information processing speed, orientation, attention, verbal learning and memory, language, visuoperception, praxis and executive functions. The aim of the present study was to establish the cut-off scores for impairment for different levels of age and education that could be useful in the cognitive assessment of Spanish subjects who are at risk for cognitive impairment, especially dementia. Data from 1018 patients with a mild dementia syndrome, and 512 cognitively healthy subjects, older than 44 years, from the Memory Clinic of Fundació ACE (Barcelona, Spain were analyzed. In the whole sample, cut-off scores and sensitivity/specificity values were calculated for six conditions after combining 3 age ranges (44 to 64; 65 to 74; and older than 74 years old by 2 educational levels (until Elementary school; and more than Elementary school. Moreover, general cut-offs are reported for Catalan and Spanish speakers. The results showed that most of NBACE tests reached good sensitivity and specificity values, except for Ideomotor praxis, Repetition and Verbal Comprehension tests, which had a ceiling effect. Word List Learning from the Wechsler Memory Scale-III and Semantic Verbal Fluency were the most useful tests to discriminate between cognitively healthy and demented subjects. The NBACE has been shown to be a useful tool able to detect cognitive impairment, especially dementia, in older than 44 years Spanish persons.

MANU. Purchase of Bentonite. Process Description

International Nuclear Information System (INIS)

Laaksonen, R.

2010-01-01

The aim of this study is to describe the entire bentonite purchasing process accurately. This will enable efficient and focused use of information related to the purchasing phase and to each individual bentonite batch. This work continues from the work started in the report by Ahonen et al. (2008), Quality Assurance of the Bentonite Material, Posiva Working Report 2008-33. The current work includes a short enquiry for all relevant and at the time known producers or re-sellers of bentonite. Questions about relevant products suitable for civil engineering use, more specifically nuclear waste disposal site use, were asked together with test methods, typical test results and test standards. The following aspects and opinions have been processed from the results that were obtained during the project. Each seller/producer has a quality management system, QMS (typically ISO 9001), and ability to perform the basic tests, but there is not an established common set of properties to be tested. Some producers are willing to test according to customers' specifications. Posiva could arrange a network of capable laboratories to carry out tests according to its selected standards. This activity should then be accredited with a reasonable testing volume. Before starting the purchase of bentonite at a large scale, Posiva should go through negotiations and audits with each seller in order to make sure that both parties are testing with the same methods and both understand the range where the values of key parameters may lie. A database is needed for gathering statistically relevant information from the bentonite material parameters over the long run. This is needed for determining the limits within which the material parameters should remain in order to be acceptable. Posiva is encouraged to create a process to optimize the test types and the amount of tests should be identified for immediate and long term use. This process ensures the required quality and costs involved. (orig.)

Determination of cosmic ray (CR) ionization path and iono/atmospheric cut-off energy from CR intervals III, IV and V in the planetary environments

International Nuclear Information System (INIS)

Velinov, P.

2001-01-01

In this paper are determined the ionization path and cut-off energies of the cosmic ray (CR) nuclei in relation to the general interaction model 'CR - ionosphere-middle atmosphere'. Here the ionization path and the iono/atmospheric cut-off energies of the galactic CR, solar CR and anomalous CR are separately considered in each energetic range, without taking into account the particle transfer from one range in another. This more general approach will be the object of a further paper

Diaphragm walling for Sizewell B sets records

International Nuclear Information System (INIS)

Anon.

1988-01-01

The first phase of construction of the Sizewell-B nuclear reactor has been completed. This was the building of a diaphragm wall around the site. It is one of the largest and deepest diaphragm walls to be installed in Europe. The site can be pumped dry of groundwater and the foundations constructed in the dry. The specifications of the wall and its construction, using two Hydrofraise excavation rigs, are described. The excavated material is brought up as a slurry and the (bentonite) slurry is cleaned and desanded. Most of the wall has been formed using a plastic concrete but reinforced concrete has been used for some stretches. The diaphragm wall, which is 1258m long and 55m deep on average, was built in 19 weeks. (U.K.)

Leaching tests of cemented organic radioactive waste

International Nuclear Information System (INIS)

Calabria, Jaqueline A. Almeida; Haucz, Maria Judite A.; Tello, Cledola Cassia O.

2011-01-01

The use of radioisotopes in research, medical and industrial activities generates organic liquid radioactive wastes. At Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) are produced organic liquid wastes from different sources, one of these are the solvent extraction activities, whose the waste volume is the largest one. Therefore a research was carried out to treat them. Several techniques to treat organic liquid radioactive wastes have been evaluated, among them incineration, oxidation processes, alkaline hydrolysis, distillation, absorption and cementation. Laboratory experiments were accomplished to establish the most adequate process in order to obtain qualified products for storage and disposal. Absorption followed by cementation was the procedure used in this study, i.e. absorbent substances were added to the organic liquid wastes before mixing with the cement. Initially were defined the absorbers, and evaluated the formulation in relation to the compressive strength of its products. Bentonite from different suppliers (B and G) and vermiculite in two granulometries (M - medium and F - small) were tested. In order to assess the product quality the specimens were submitted to the leaching test according the Standard ISO 6961 and its results were evaluated. Then they were compared with the values established by Standard CNEN NN 6.09 A cceptance criteria for waste products to be disposed , to verify if they meet the requirements for safely storage and disposal. Through this study the best formulations to treat the organic wastes were established. (author)

A study of insulin resistance by HOMA-IR and its cut-off value to identify metabolic syndrome in urban Indian adolescents.

Science.gov (United States)

Singh, Yashpal; Garg, M K; Tandon, Nikhil; Marwaha, Raman Kumar

2013-01-01

Insulin resistance (IR) and associated metabolic abnormalities are increasingly being reported in the adolescent population. Cut-off value of homeostasis model of assessment IR (HOMA-IR) as an indicator of metabolic syndrome (MS) in adolescents has not been established. This study aimed to investigate IR by HOMA-IR in urban Indian adolescents and to establish cut-off values of HOMA-IR for defining MS. A total of 691 apparently healthy adolescents (295 with normal body mass index (BMI), 205 overweight, and 199 obese) were included in this cross-sectional study. MS in adolescents was defined by International Diabetes Federation (IDF) and Adult Treatment Panel III (ATP III) criteria. IR was calculated using the HOMA model. Mean height, waist circumference (WC), waist/hip ratio (WHR), waist/height ratio (WHtR), and blood pressure were significantly higher in boys as compared to girls. The HOMA-IR values increased progressively from normal weight to obese adolescents in both sexes. Mean HOMA-IR values increased progressively according to sexual maturity rating in both sexes. HOMA-IR value of 2.5 had a sensitivity of >70% and specificity of >60% for MS. This cut-off identified larger number of adolescents with MS in different BMI categories (19.7% in normal weight, 51.7% in overweight, and 77.0% in obese subjects) as compared to the use of IDF or ATP III criteria for diagnosing MS. Odds ratio for having IR (HOMA-IR of >2.5) was highest with WHtR (4.9, p pHOMA-IR increased with sexual maturity and with progression from normal to obese. A HOMA-IR cut-off of 2.5 provided the maximum sensitivity and specificity in diagnosing MS in both genders as per ATP III and IDF criteria.

Effect of seawater and high-temperature history on swelling characteristics of bentonite

International Nuclear Information System (INIS)

Tanaka, Yukihisa; Nakamura, Kunihiko

2005-01-01

In the case of construction of repository for nuclear waste near the coastal area, the effect of seawater on swelling characteristics of bentonite as an engineering as an engineering barrier should be considered. Effects of high-temperature history on swelling characteristics of bentonite should also be considered because nuclear waste generates heat. Thus, in this study, swelling characteristics of bentonite on the conditions of high temperature history and seawater are investigated. The results of this study imply that : (1) Swelling strain of sodium bentonite or transformed sodium bentonite decrease as the salinity of water increases, whereas those of calcium bentonite are not affected by salinity of the water. (2) Quantitative evaluation method for swelling strain and swelling pressure of several kinds of bentonites under brine is proposed. (3) Using distilled water, swelling strain and swelling pressure of sodium bentonite with high-temperature history is less than those without high-temperature history. (author)

Welding and cutting characteristics of blanket/first wall module to back plate for fusion experimental reactor

International Nuclear Information System (INIS)

Sato, Shinichi; Osaki, Toshio; Koga, Shinji

1996-01-01

The first wall and the blanket of the International Thermonuclear Experimental Reactor (ITER) are used under severe conditions such as the neutron irradiation by plasma, surface thermal load, the electromagnetic force at the time of plasma disruption and others. Consequently, from the viewpoint of the necessity for disassembling and maintenance, those are divided into modules in toroidal and poloidal directions. In this study, as to the welding of the back plate and the legs supporting blanket modules, which are installed in a vacuum vessel, the characteristic test paying attention to the deformation at the time of welding was carried out, and the optimal welding conditions and the characteristics of welding deformation and others were clarified. Moreover, when water jet method was used for cutting the welded parts of the supporting legs, the properties of the cut parts, the time for cutting and others were examined. The performance required for the welded parts of blanket modules with back plate is shown. The basic test of welding conditions using plate models, partial model test and whole model test are reported. The test of water jet cutting for the maintenance of shielding blanket modules is described. (K.I.)

Receiver Operating Characteristic (ROC to Determine Cut-Off Points of Biomarkers in Lung Cancer Patients

Directory of Open Access Journals (Sweden)

Heidi L. Weiss

2004-01-01

Full Text Available The role of biomarkers in disease prognosis continues to be an important investigation in many cancer studies. In order for these biomarkers to have practical application in clinical decision making regarding patient treatment and follow-up, it is common to dichotomize patients into those with low vs. high expression levels. In this study, receiver operating characteristic (ROC curves, area under the curve (AUC of the ROC, sensitivity, specificity, as well as likelihood ratios were calculated to determine levels of growth factor biomarkers that best differentiate lung cancer cases versus control subjects. Selected cut-off points for p185erbB-2 and EGFR membrane appear to have good discriminating power to differentiate control tissues versus uninvolved tissues from patients with lung cancer (AUC = 89% and 90%, respectively; while AUC increased to at least 90% for selected cut-off points for p185erbB-2 membrane, EGFR membrane, and FASE when comparing between control versus carcinoma tissues from lung cancer cases. Using data from control subjects compared to patients with lung cancer, we presented a simple and intuitive approach to determine dichotomized levels of biomarkers and validated the value of these biomarkers as surrogate endpoints for cancer outcome.

Tracer diffusion in compacted, water-saturated bentonite

International Nuclear Information System (INIS)

Bourg, Ian C.; Sposito, Garrison; Bourg, Alain C.M.

2005-01-01

Compacted Na-bentonite clay barriers, widely used in the isolation of solid-waste landfills and other contaminated sites, have been proposed for a similar use in the disposal of high-level radioactive waste. Molecular diffusion through the pore space in these barriers plays a key role in their performance, thus motivating recent measurements of the apparent diffusion coefficient tensor of water tracers in compacted, water-saturated Na-bentonites. In the present study, we introduce a conceptual model in which the pore space of water-saturated bentonite is divided into 'macropore' and 'interlayer nanopore' compartments. With this model we determine quantitatively the relative contributions of pore-network geometry (expressed as a geometric factor) and of the diffusive behavior of water molecules near montmorillonite basal surfaces(expressed as a contrastivity factor) to the apparent diffusion coefficient tensor. Our model predicts, in agreement with experiment, that the mean principal value of the apparent diffusion coefficient tensor follows a single relationship when plotted against the partial montmorillonite dry density (mass of montmorillonite per combined volume of montmorillonite and pore space). Using a single fitted parameter, the mean principal geometric factor, our model successfully describes this relationship for a broad range of bentonite-water system, from dilute gel to highly-compacted bentonite with 80 percent of its pore water in interlayer nanopores

Modelling the evolution of compacted bentonite clays in engineered barrier systems: process model development of the bentonite-water-air system

International Nuclear Information System (INIS)

Bond, A.E.; Wilson, J.C.; Maul, P.R.; Robinson, P.C.; Savage, D.

2010-01-01

Document available in extended abstract form only. An adequate understanding of the short- and long-term evolution of compacted bentonite clays in engineered barrier systems (EBS) for radioactive waste based on the KBS-3 disposal concept is an essential requirement for demonstrating the safe performance of the system. Uncertainties in the way that the re-saturation process occurs are intrinsically tied to the thermal and mechanical evolution of the bentonite buffer and its interaction with the disposal canister and host-rock. Furthermore, the evolution of bentonite in the presence of changing ambient saturation states, groundwater chemistry and stress states could cause the bentonite re-saturation and long-term stability (including the so-called 'buffer erosion scenario') to deviate from the behaviour required by the safety case; this has emphasised the need to consider adequately coupled thermal (T), hydraulic(H), mechanical (M) and chemical (C) processes. Historically, there have been fundamental differences in the representation of porosity and water disposition between geochemical modelling and coupled THM modelling studies. In this paper, a model for the porosity and water disposition in bentonite is presented that is more detailed than models used to date in most THM modelling studies under variably saturated conditions. The new model moves away from the conventional THM soils approach which treats bentonite as an elasto-plastic porous medium with water or air occupying a notional porosity with the inclusion of additional process models to take into account the very high observed water suctions, intrinsic permeability variation and macroscopic swelling of partially saturated compacted bentonite. It replaces the empirical parameterisation usually employed in THM models with a direct representation of the water disposition, pore structure and relevant processes, albeit at an abstracted level. The new model differentiates between water which can be

Radiation shielding wall structure

International Nuclear Information System (INIS)

Nishimura, Yoshitaka; Oka, Shinji; Kan, Toshihiko; Misato, Takeshi.

1990-01-01

A space between a pair of vertical steel plates laterally disposed in parallel at an optional distance has a structure of a plurality of vertically extending tranks partitioned laterally by vertically placed steel plates. Then, cements are grouted to the tranks. Strip-like steel plates each having a thickness greater than the gap between the each of the vertically placed steel plates and the cement are bonded each at the surface for each of the vertically placed steel plates opposing to the cements. A protrusion of a strip width having radiation shielding performance substantially identical with that by the thickness of the cement is disposed in the strip-like steel plates. With such a constitution, a safety radiation shielding wall structure with no worry of radiation intrusion to gaps, if formed, between the steel plates and the grouted cements due to shrinkage of the cements. (I.N.)

Wyoming bentonites. Evidence from the geological record to evaluate the suitability of bentonite as a buffer material during the long-term underground containment of radioactive wastes

International Nuclear Information System (INIS)

Smellie, J.

2001-12-01

In the Swedish programme for the deep, geological disposal of radioactive wastes, bentonite is planned to be used as a barrier material to reduce groundwater flow and minimise radionuclide migration into the geosphere. One of the possible threats to long-term bentonite stability is the gradual incursion of saline water into the repository confines which may reduce the swelling capacity of the bentonite, even to the extent of eliminating the positive effects of mixing bentonite into backfill materials. Important information may be obtained from the study of analogous processes in nature (i.e. natural analogue or natural system studies) where bentonite, during its formation, has been in long-term contact with reducing waters of brackish to saline character. Type bentonites include those mined from the Clay Spur bed at the top of the Cretaceous Mowry Formation in NE Wyoming and demarcated for potential use as a barrier material (e.g. MX-80 sodium bentonite) in the Swedish radioactive waste programme. This bentonite forms part of the Mowry Shale which was deposited in a southern embayment of the late Albian Western Interior Cretaceous sea (Mowry Sea). The question is whether these bentonite deposits show evidence of post-deposition alteration caused by the sea water in which they were deposited, and/or, have they been altered subsequently by contact with waters of increasing salinity? Bentonites are the product of pyroclastic fall deposits thought to be generated by the type of explosive, subaerial volcanic activity characteristic of Plinian eruptive systems. In Wyoming the overall composition of the original ash varied from dacite to rhyolite, or latite to trachyte. The ash clouds were carried to high altitudes and eastwards by the prevailing westerly winds before falling over the shallow Mowry Sea and forming thin but widespread and continuous horizons on sea floor muds and sands. Whilst bentonites were principally wind-transported, there is evidence of some water

Wyoming bentonites. Evidence from the geological record to evaluate the suitability of bentonite as a buffer material during the long-term underground containment of radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

Smellie, J [Conterra AB (Sweden)

2001-12-01

In the Swedish programme for the deep, geological disposal of radioactive wastes, bentonite is planned to be used as a barrier material to reduce groundwater flow and minimise radionuclide migration into the geosphere. One of the possible threats to long-term bentonite stability is the gradual incursion of saline water into the repository confines which may reduce the swelling capacity of the bentonite, even to the extent of eliminating the positive effects of mixing bentonite into backfill materials. Important information may be obtained from the study of analogous processes in nature (i.e. natural analogue or natural system studies) where bentonite, during its formation, has been in long-term contact with reducing waters of brackish to saline character. Type bentonites include those mined from the Clay Spur bed at the top of the Cretaceous Mowry Formation in NE Wyoming and demarcated for potential use as a barrier material (e.g. MX-80 sodium bentonite) in the Swedish radioactive waste programme. This bentonite forms part of the Mowry Shale which was deposited in a southern embayment of the late Albian Western Interior Cretaceous sea (Mowry Sea). The question is whether these bentonite deposits show evidence of post-deposition alteration caused by the sea water in which they were deposited, and/or, have they been altered subsequently by contact with waters of increasing salinity? Bentonites are the product of pyroclastic fall deposits thought to be generated by the type of explosive, subaerial volcanic activity characteristic of Plinian eruptive systems. In Wyoming the overall composition of the original ash varied from dacite to rhyolite, or latite to trachyte. The ash clouds were carried to high altitudes and eastwards by the prevailing westerly winds before falling over the shallow Mowry Sea and forming thin but widespread and continuous horizons on sea floor muds and sands. Whilst bentonites were principally wind-transported, there is evidence of some water

Durability of saw-cut joints in plain cement concrete pavements.

Science.gov (United States)

2011-01-01

The objective of this project was to evaluate factors influencing the durability of the joints in portland cement concrete : pavement in the state of Indiana. Specifically this work evaluated the absorption of water, the absorption of deicing solutio...

The cut-off values of dietary energy intake for determining metabolic syndrome in hemodialysis patients: A clinical cross-sectional study

Science.gov (United States)

Duong, Tuyen Van; Wong, Te-Chih; Chen, Hsi-Hsien; Chen, Tzen-Wen; Chen, Tso-Hsiao; Hsu, Yung-Ho; Peng, Sheng-Jeng; Kuo, Ko-Lin; Wang, Chi-Sin; Tseng, I-Hsin; Feng, Yi-Wei; Chang, Tai-Yue; Su, Chien-Tien

2018-01-01

Dietary energy intake strongly linked to dialysis outcomes. We aimed to explore the optimal cut-off point of energy intake (EI) for identification of metabolic syndrome (MetS) in hemodialysis patients. The cross-sectional data of 243 hemodialysis patients from multi-dialysis centers in Taiwan was used. The dietary intake was assessed by using the three-day dietary questionnaire, and a 24-hour dietary recall, clinical and biochemical data were also evaluated. The MetS was diagnosed by the Harmonized Metabolic Syndrome criteria. The receiver operating characteristic (ROC) curve was to depict the optimal cut-off value of EI for the diagnosis of MetS. The logistic regression was also used to explore the association between inadequate EI and MetS. The optimal cut-off points of EI for identifying the MetS were 26.7 kcal/kg/day for patients aged less than 60 years, or with non-diabetes, and 26.2 kcal/kg/day for patients aged 60 years and above, or with diabetes, respectively. The likelihood of the MetS increased with lower percentiles of energy intake in hemodialysis patients. In the multivariate analysis, the inadequate dietary energy intake strongly determined 3.24 folds of the MetS. The assessment of dietary EI can help healthcare providers detecting patients who are at risk of metabolic syndrome. PMID:29538427

Development and application of a packer-type drilling-free liner hanger

Directory of Open Access Journals (Sweden)

Xin Tang

2014-12-01

Full Text Available In liner cementing, the upper cement plug and inner components of a common hanger needs to be drilled out after cementing, which will result in a poor cementing quality or even gas leakage at the flare opening. Therefore, a new packer-type drilling-free liner hanger has been developed, and a hydraulic setting-control packer, a flexible drilling-free seal box, and an auxiliary bearing back-off mechanism that go with the line hanger have been designed at the same time. Specific operation procedures include: (1 run in the liner string to the designed depth, then fully circulate the drilling fluid, finally drop the ball. When the tripping ball gets into the seat, the pressure will go up to cut off the hanging control pin and set the hanger; (2 continue to hold the pressure and cut off the ball seat pin to form circulation; (3 trip in the drill pipe to exert pressure on the hanger, back off to release the hanger from the running tool; (4 lower the drill pipe plug upon the completion of cement injection, cut off the releasing control pin of hollow casing plug, and run down further to bump with the bumping assembly; (5 remove the cementing head and connect the kelly driver, hold pressure again, then slowly pull up the drill tools, exert hydraulic pressure on the setting hydraulic cylinder of the packer assembly to cut off the setting control pin and set the packer; and (6 pull up the tools to the flare opening and wash out excessive cement slurry by circulating to realize free drilling of the whole hole. The successful application of the liner hanger in 127 mm diameter liner in Well BQ203-H1 indicates that the packer-type liner hanger has such advantages as easy hanging and back-off, accurate bumping, simple setting, and sound sealing performance.

The Optimal Cut-Off Value of Neutrophil-to-Lymphocyte Ratio for Predicting Prognosis in Adult Patients with Henoch–Schönlein Purpura

Science.gov (United States)

Park, Chan Hyuk; Han, Dong Soo; Jeong, Jae Yoon; Eun, Chang Soo; Yoo, Kyo-Sang; Jeon, Yong Cheol; Sohn, Joo Hyun

2016-01-01

Background The development of gastrointestinal (GI) bleeding and end-stage renal disease (ESRD) can be a concern in the management of Henoch–Schönlein purpura (HSP). We aimed to evaluate whether the neutrophil-to-lymphocyte ratio (NLR) is associated with the prognosis of adult patients with HSP. Methods Clinical data including the NLR of adult patients with HSP were retrospectively analyzed. Patients were classified into three groups as follows: (a) simple recovery, (b) wax & wane without GI bleeding, and (c) development of GI bleeding. The optimal cut-off value was determined using a receiver operating characteristics curve and the Youden index. Results A total of 66 adult patients were enrolled. The NLR was higher in the GI bleeding group than in the simple recovery or wax & wane group (simple recovery vs. wax & wane vs. GI bleeding; median [IQR], 2.32 [1.61–3.11] vs. 3.18 [2.16–3.71] vs. 7.52 [4.91–10.23], P<0.001). For the purpose of predicting simple recovery, the optimal cut-off value of NLR was 3.18, and the sensitivity and specificity were 74.1% and 75.0%, respectively. For predicting development of GI bleeding, the optimal cut-off value was 3.90 and the sensitivity and specificity were 87.5% and 88.6%, respectively. Conclusions The NLR is useful for predicting development of GI bleeding as well as simple recovery without symptom relapse. Two different cut-off values of NLR, 3.18 for predicting an easy recovery without symptom relapse and 3.90 for predicting GI bleeding can be used in adult patients with HSP. PMID:27073884

Iodine sorption of bentonite - radiometric and polarographic study

International Nuclear Information System (INIS)

Konirova, R.; Vinsova, H.; Koudelkova, M.; Ernestova, M.; Jedinakova-Krizova, V.

2003-01-01

The experiments focused on kinetics of iodine retardation on bentonite, influence of aqueous phase pH, buffering properties of bentonite, etc. were carried out by batch method. Distribution coefficient KD was the criterion applied for evaluation of iodine interaction with solid phase. High sorption potential of bentonite to cationic forms of various radionuclides, resulting from relatively high cation exchange capacity, is generally known. On the other hand the inorganic anions are not adsorbed strongly to mineral surface of clays thus uptake of iodine (occurring mainly at iodide (I - ) or iodate (IO 3 - ) form under oxoic conditions) is limited. The distribution coefficients of iodine anions' sorption on bentonite R reach order of magnitude 10 -1 mL/g. In order to increase the sorption capacity of the solid phase, several additives were added to bentonite. Most of them didn't provide satisfactory results except of the addition of activated carbon, which has high surface area. Electromigration and polarographic methods were used for investigation of the redox state of iodine in aqueous phase and determination of KD values as well. Acquired results were compared with data obtained by radiometric measurements. (authors)

Study on the basic property of Gaomiaozi bentonite, inner mongolia

International Nuclear Information System (INIS)

Liu Yuemiao; Xu Guoqing; Liu Shufen; Chen Zhangru

2001-01-01

Buffer/backfill material layer is one of important engineered barriers in the HLW geological repository. The geologic setting of Gaomiaozi bentonite deposit is introduced, and the mineral composition, physical and chemical property, basic geotechnical property, swelling property and permeability of highly compacted bentonite of main ore bed has been studied. The study results show that montmorillonite content of Gaomiaozi bentonite is relatively high, physical and chemical property, geotechnical property and impermeability are good. So Gaomiaozi bentonite deposit could be regarded as supply base of buffer/backfill material for HLW geological repository

Prognostic impact of proliferation for resected early stage 'pure' invasive lobular breast cancer: Cut-off analysis of Ki67 according to histology and clinical validation.

Science.gov (United States)

Carbognin, Luisa; Sperduti, Isabella; Fabi, Alessandra; Dieci, Maria Vittoria; Kadrija, Dzenete; Griguolo, Gaia; Pilotto, Sara; Guarneri, Valentina; Zampiva, Ilaria; Brunelli, Matteo; Orvieto, Enrico; Nortilli, Rolando; Fiorio, Elena; Parolin, Veronica; Manfrin, Erminia; Caliò, Anna; Nisticò, Cecilia; Pellini, Francesca; Scarpa, Aldo; Pollini, Giovanni Paolo; Conte, Pierfranco; Tortora, Giampaolo; Bria, Emilio

2017-10-01

The intent of this analysis was to investigate and validate the prognostic potential of Ki67 in a multi-center series of patients affected by early stage 'pure' invasive lobular carcinoma (ILC). Clinical-pathological data of patients affected by ILC were correlated with overall survival and disease-free survival (OS/DFS); data from a parallel invasive ductal carcinoma (IDC) patients' cohort were gathered as well. The maximally selected Log-Rank statistics analysis was applied to Ki67 continuous variable to estimate the appropriate cut-off. The Subpopulation Treatment Effect Pattern Plot (STEPP) analysis was performed as well. Data from overall 1097 (457/222 ILC: training/validation set; 418 IDC) patients were gathered. The identified optimal Ki67 cut-offs were 4% and 14% for DFS in ILC and IDC cohort, respectively. In ILC patients, the Ki67 cut-off was an independent OS predictor. Ten-years OS and DFS were 89.9% and 77.2% (p = 0.007) and 79.4% and 69.2% (p = 0.03) for patients with Ki67 ≤ 4% and >4%, respectively. In IDC patients, 10-years OS was 93.8% and 71.7%, p = 0.02, DFS was 84.0% and 52.6%, p = 0.0003, for patients with Ki67 ≤ 14% and >14%, respectively. In the validation set, the optimal Ki67 OS cut-off was 5%. The STEPP analysis showed that in the presence of low Ki67 values, IDC patients have a better DFS than ILC patients, while with the increase of values the prognosis tends to overlap. Despite the retrospective design of the study, the prognostic relevance of Ki67 (as well as its optimal cut-off) seems to significantly differ according to breast cancer histology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of alkaline (PH 8.3-12.0) and saline solutions on chemical, mineralogical and physical properties of two different bentonites - batch experiments at 25 deg. C

International Nuclear Information System (INIS)

Heikola, Tiina; Vuorinen, Ulla; Kumpulainen, Sirpa; Kiviranta, Leena; Korkeakoski, Petri

2012-01-01

Document available in extended abstract form only. Construction of a spent fuel repository deep in the bedrock will need supporting structures using cement materials. A part of them can be removed before closure but still it is estimated that about 1000 tonnes will remain in the host rock. Degradation of cementitious materials produces leachates of high pH. If such an alkaline plume reaches the bentonite buffer, it may induce mineralogical and chemical changes in bentonite over long term, and further affect the safety functions of the buffer. Laboratory experiments were done with the objective to gain data of possible alterations in mineralogical, chemical and physical properties of bentonites contacted with high-pH saline solutions. Two untreated, high grade, Na- and Ca-bentonites, were used in batch experiments, which were carried out in an anaerobic glove-box at 25±1 deg. C for 554 days. Each bentonite sample (20 g) was leached with approximately 3.8 L of leaching solution, which equals 190 mL/g of bentonite. The bentonites were leached with three types of simulated cement waters (pH 9.7, 11.3 and 12.0) and one saline groundwater simulate (pH 8.3) as a reference. The leaching solutions were 0.3 M, and contained NaCl and CaCl 2 , and trace amounts of SiO 2 , K, Br, Mg and SO 4 . Dissolved oxygen and carbon dioxide were removed from leaching solutions before mixing of bentonite in PC bottles. The samples were placed on a platform shaker in order to allow better contact between bentonite and the leaching solution. The evolution of pH in the samples was followed by measuring the pH-value of each sample in the solution phase approximately twice a week and the solution was renewed when values of two to three consecutive measurements did not change. On average, the leaching solution was renewed once a month. For each renewal of the leaching solution the phases were separated, the reacted solution withdrawn, and the chemical composition analysed. Before analysis the

Behavior of plutonium interacting with bentonite and sulfate-reducing anaerobic bacteria

International Nuclear Information System (INIS)

Kudo, A.; Zheng, J.; Cayer, I.; Fujikawa, Y.; Yoshikawa, H.; Ito, M.

1997-01-01

The interactions between sulfate reducing anaerobic bacteria and plutonium, with or without bentonite present, were investigated using distribution coefficients [Kd (ml/g)] as an index of the radionuclide behavior. Plutonium Kds for living bacteria varied within a large range, from 1,804 to 112,952, depending on the pH, while the Kds ranged from 1,180 to 5,931 for dead bacteria. In general, living bacteria had higher plutonium Kds than dead bacteria. Furthermore, the higher Kd values of 39,677 to 106,915 for living bacteria were obtained for a pH range between 6.83 and 8.25, while no visible pH effect was observed for dead bacteria. These Kd values were obtained using tracers for both 236 Pu and 239 Pu, which can check the experimental procedures and mass balance. Another comparison was conducted for plutonium Kd values of mixtures of living bacteria with bentonite and sterilized bacteria with bentonite. The range of Kd values for the non-sterilized bacteria with bentonite were 1,194 to 83,648 while Kd values for the sterilized bacteria with bentonite were from 624 to 17,236. Again, the Kd values for the living bacteria with bentonite were higher than those of sterilized bacteria with bentonite. In other words, the presence of living anaerobic bacteria with bentonite increased, by roughly 50 times, the Kd values of 239 Pu when compared to the mixture of dead bacteria with bentonite. The results indicate that the effects of anaerobic bacteria within the engineered barrier system (in this case bentonite) will play a significant role in the behavior of plutonium in geologic repositories

Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions. Part 1. Permeability change of compacted bentonite immersed in alkaline solutions

International Nuclear Information System (INIS)

Yokoyama, Shingo; Nakamura, Kunihiko

2010-01-01

Permeability tests using the compacted bentonites and alkaline solutions were carried out to estimate of alteration behavior and the change of permeability during the alteration reaction. The permeability tests of the compacted bentonites were carried out at 23degC for one week after they were immersed in alkaline solution at 60degC for four weeks (immersing test). After permeability tests, the compacted bentonites were repeatedly tested as the same procedure (i.e. repetition of permeability test and immersing test) at 11 cycles. The compacted bentonites with initial dry density of 1.6 Mg/m 3 were reacted with the different type of the alkaline solutions (deionized water, NaOH (pH=12 and 14), KOH (pH=12 and 14) and Ca(OH) 2 (pH=12)) in each experiments. In the case of deionized water and alkaline solutions of pH12, the mineral compositions of altered bentonite were similar to original bentonite while the exchangeable cations of altered bentonites were changed. No changes of the mineralogical features of montmorillonite in altered bentonites (i.e. illitization, baideritization and increasing of layer charge) were observed in the case of deionized water, pH12-NaOH and pH12-Ca(OH) 2 . The montmorillonite was changed to the illite/smectite interstratified mineral containing about 40% illite like component during the reaction with pH12-KOH. In the case of alkaline solutions with pH14, the component minerals of bentonite (e.g. montmorillonite, quartz and clinoptilolite) were dissolved, consequently secondly minerals (e.g. analcime and phillipsite) were crystallized during experiments. Furthermore, the mineralogical features of montmorillonite were changed as illitization (pH14-KOH), beidellitization (pH14-NaOH and pH14-KOH) and increasing of layer charge (pH14-NaOH and pH14-KOH). No increasing of permeability were observed during the experiment using pH12-NaOH and pH12-Ca(OH) 2 as well as the case of deionized water. In the case of pH12-KOH, the permeability continually

Modelling interaction of deep groundwaters with bentonite and radionuclide speciation

International Nuclear Information System (INIS)

Wanner, H.

1986-04-01

In the safety analysis recently reported for a potential Swiss high-level waste repository, radionuclide speciation and solubility limits are calculated for expected granitic groundwater conditions. With the objective of deriving a more realistic description of radionuclide release from the near-field, an investigation has been initiated to quantitatively specify the chemistry of the near-field. In the Swiss case, the main components of the near-field are the glass waste-matrix, a thick steel canister horizontally emplaced in a drift, and a backfill of highly compacted sodium bentonite. This report describes a thermodynamic model which is used to estimate the chemical composition of the pore water in compacted sodium bentonite. Solubility limits and speciation of important actinides and the fission product technetium in the bentonite pore water are then calculated. The model is based on available experimental data on the interaction of sodium bentonite and groundwater and represents means of extrapolation from laboratory data to repository conditions. The basic reactions between sodium bentonite and groundwater are described by an ion-exchange model for sodium, potassium, magnesium, and calcium. The model assumes equilibrium with calcite as long as sufficient carbonates remain in the bentonite, as well as quartz saturation. It is calculated that the pore water of compacted sodium bentonite saturated with Swiss Reference Groundwater will have a pH value of 9.7 and a free carbonate activity of 8x10 -4 M. The long-term situation is modelled by the assumption that the near-field of a deep repository behaves like a mixing tank. In this way, an attempt is made to account for the continuous water exchange between the near-field and the host rock. It is found that sodium bentonite will be slowly converted to calcium bentonite. This conversion is roughly estimated to be completed after 2 million years

Bond strength of resin modified glass ionomer cement to primary dentin after cutting with different bur types and dentin conditioning

Directory of Open Access Journals (Sweden)

Rebeca Di Nicoló

2007-10-01

Full Text Available The aim of this in vitro study was to evaluate the effect of different bur types and acid etching protocols on the shear bond strength (SBS of a resin modified glass ionomer cement (RM-GIC to primary dentin. Forty-eight clinically sound human primary molars were selected and randomly assigned to four groups (n=12. In G1, the lingual surface of the teeth was cut with a carbide bur until a 2.0-mm-diameter dentin area was exposed, followed by the application of RM-GIC (Vitremer - 3M/ESPE prepared according to the manufacturer's instructions. The specimens of G2, received the same treatment of G1, however the dentin was conditioned with phosphoric acid. In groups G3 and G4 the same procedures of G1 and G2 were conducted respectively, nevertheless dentin cutting was made with a diamond bur. The specimens were stored in distilled water at 37ºC for 24h, and then tested in a universal testing machine. SBS. data were submitted to 2-way ANOVA (= 5% and indicated that SBS values of RM-GIC bonded to primary dentin cut with different burs were not statistically different, but the specimens that were conditioned with phosphoric acid presented SBS values significantly higher that those without conditioning. To observe micromorphologic characteristics of the effects of dentin surface cut by diamond or carbide rotary instruments and conditioners treatment, some specimens were examined by scanning electron microscopy. Smear layer was present in all specimens regardless of the type of rotary instrument used for dentin cutting, and specimens etched with phosphoric acid presented more effective removal of smear layer. It was concluded that SBS of a RM-GIC to primary dentin was affected by the acid conditioning but the bur type had no influence.

Modified swelling pressure apparatus using vapor pressure technique for compacted bentonite

International Nuclear Information System (INIS)

Nishimura, Tomoyoshi

2012-01-01

Document available in extended abstract form only. bentonite. The compacted bentonite is found in unsaturated conditions before applying of swelling due to absorption. The behaviour of compacted bentonite is not consistent with the principle and concepts of classical, saturated soil mechanics. An unsaturated soil theoretical framework using soil water characteristic curve has been fairly established over the past several decades. The soil-water characteristic curve is a relationship between soil moisture and soil suction obtained by the axis translation technique, vapor pressure technique or osmotic suction control which is a key feature in unsaturated soil mechanics. The soil-water characteristic curve can be used for prediction of the shear strength, volume change and hydraulic conductivity. Cui et al. 2002 indicated soil-water characteristic curve of expansive clay soil in high soil suction ranges using osmotic suction technique. Tripathy et al. 2010 described the soil-water characteristic curve both using the axis translation technique and vapor pressure technique in the entire soil suction ranges. Nishimura and Koseki 2011 measured suction of bentonite applied high soil suction due vapor pressure using a chilled mirror dew point potentiometer (WP4-T of DECAGON Device). The bentonite with gravimetric water content of 18 % indicated soil suction of 2.8 MPa at least. It is predicted that suction efforts to swelling pressure and shear strength of unsaturated compacted bentonite. This study focuses on the influence of suction on both swelling pressure and shear strength of compacted bentonite. The soil-water characteristic curve (SWCC) tests were conducted for compacted bentonite using both axis-translation technique and vapor pressure technique. The SWCC had a range from 0 kPa to 296 MPa in suction. The compacted bentonite having two different soil suctions were prepared for swelling pressure tests. Newly swelling pressure testing apparatus was developed in order

Thermo-mechanical cementation effects in bentonite investigated by unconfined compression tests

International Nuclear Information System (INIS)

Dueck, Ann

2010-01-01

Results from the project LOT showed that specimens exposed to warm conditions had a significantly reduced strain at failure compared to reference material. The objective of the present study was to investigate the impact of parameters such as temperature, density, water content and degree of saturation on the occurrence of brittleness at failure of bentonite specimens. To quantify the influence of the different parameters the unconfined compression test was used on specimens with a height and diameter of 20 mm. In this test the relation between stress and strain is determined from axial compression of a cylindrical specimen. Brittle failure is in this investigation mainly seen on specimens having a density of ρ ≥ 2,060 kg/m 3 or on specimens exposed to high temperature T ≥ 150 deg C in the laboratory. Brittle failure behaviour was also seen on unsaturated specimens with a degree of saturation less than Sr i = 0% before saturation, on specimens with a final degree of saturation of S r ≤ 97% and also on one specimen subjected to consolidation during preparation. Brittle failure and reduced strain were noticed in the heated field exposed material in the LOT project. Similar behaviour was also observed in the present short term laboratory tests. However, the specimens in the present study showing this behaviour had higher density, lower degree of saturation or were exposed to higher temperatures than the field exposed specimens

Bentonite erosion. Final report

Energy Technology Data Exchange (ETDEWEB)

Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

2009-12-15

Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

Bentonite erosion. Final report

International Nuclear Information System (INIS)

Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf

2009-12-01

Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

Numerical simulation of alteration of sodium bentonite by diffusion of ionic groundwater components