Translucency changes of direct esthetic restorative materials after curing, aging and treatment

Directory of Open Access Journals (Sweden)

Yong-Keun Lee

2016-11-01

Full Text Available The purpose of this article was to review the changes in translucency of direct esthetic restorative materials after curing, aging and treatment. As a criterion for the evaluation of clinical translucency changes, visual perceptibility threshold in translucency parameter difference (ΔTP of 2 was used. Translucency changes after curing were perceivable depending on experimental methods and products (largest ΔTP in resin composites = 15.9. Translucency changes after aging were reported as either relatively stable or showed perceivable changes by aging protocols (largest ΔTP in resin composites = -3.8. Translucency changes after curing, aging and treatment were perceivable in several products and experimental methods. Therefore, shade matching of direct esthetic materials should be performed considering these instabilities of translucency in direct esthetic materials.

A data base for aging of structural materials

International Nuclear Information System (INIS)

Oland, C.B.; Naus, D.J.; Jerath, S.

1993-01-01

The U.S. Nuclear Regulatory Commission (USNRC) initiated a Structural Aging (SAG) Program at the Oak Ridge National Laboratory (ORNL). The objective of the program is to provide assistance in identifying potential structural safety issues and to establish acceptance criteria for use in nuclear power plant evaluations for continued service. One of the main parts of the program focuses on the development of a Structural Materials Information Center where long-term and environment-dependent material properties are being collected and assembled into a data base. This data base is presented in two complementary formats. The Structural Materials Handbook is an expandable, hard-copy reference document that contains the complete data base for each material. The Structural Materials Electronic Data Base is accessible using an IBM-compatible personal computer. This paper presents an overview of the Structural Materials Information Center and briefly describes the features of the handbook and the electronic data base. In addition, a proposed method for using the data base to establish current property values for materials in existing concrete structures and to estimate the future performance of these materials is also presented. (author)

230Th-234U Model-Ages of Some Uranium Standard Reference Materials

International Nuclear Information System (INIS)

Williams, R.W.; Gaffney, A.M.; Kristo, M.J.; Hutcheon, I.D.

2009-01-01

The 'age' of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to its source. To the extent that the sample obeys the standard rules of radiochronometry, then the production ages of even very recent material can be determined using the 230 Th- 234 U chronometer. These standard rules may be summarized as (a) the daughter/parent ratio at time=zero must be known, and (b) there has been no daughter/parent fractionation since production. For most samples of uranium, the 'ages' determined using this chronometer are semantically 'model-ages' because (a) some assumption of the initial 230 Th content in the sample is required and (b) closed-system behavior is assumed. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for samples where both rules are met. The U isotopic standards have known purification and production dates, and closed-system behavior in the solid form (U 3 O 8 ) may be assumed with confidence. We present here 230 Th- 234 U model-ages for several of these standards, determined by isotope dilution mass spectrometry using a multicollector ICP-MS, and compare these ages with their known production history

Microstructures and mechanical properties of aging materials

International Nuclear Information System (INIS)

Liaw, P.K.; Viswanathan, R.; Murty, K.L.; Simonen, E.P.; Frear, D.

1993-01-01

This book contains a collection of papers presented at the symposium on ''Microstructures and Mechanical Properties of Aging Materials,'' that was held in Chicago, IL. November 2-5, 1992 in conjunction with the Fall Meeting of The Minerals, Metals and Materials Society (TMS). The subjects of interest in the symposium included: (1) mechanisms of microstructural degradation, (2) effects of microstructural degradation on mechanical behavior, (3) development of life prediction methodology for in-service structural and electronic components, (4) experimental techniques to monitor degradation of microstructures and mechanical properties, and (5) effects of environment on microstructural degradation and mechanical properties. Individual papers have been processed separately for inclusion in the appropriate data bases

Dose rate effect on material aging due to radiation. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Okamoto, Shin-ichi (Radiation Center of Osaka Prefecture, Sakai (Japan)); Hayakawa, Chikara; Takeya, Chikashi

1982-12-01

Although many reports have been presented on the radiation aging of the organic materials for electric cables, those have been based on the experiments carried out at high dose rate near 1 x 10/sup 6/ rad/h, assuming that aging effect depends on only radiation dose. Therefore, to investigate the aging behaviour in low dose rate range is an important subject to predict their practical life time. In this report, the results of having investigated the aging behaviour of six types of materials are described, (polyethylene for general insulation purpose, chemically cross-linked polyethylene, fire-retardant chemically cross-linked polyethylene, fire-retardant ethylene-propylene rubber, fire-retardant chloro-sulfonated polyethylene for sheaths, and fire-retardant, low hydrochloric acid, special heat-resistant vinyl for insulation purpose or chloroclean). They were irradiated with /sup 60/Co ..gamma..-ray at the dose from 5 x 10/sup 3/ to 1 x 10/sup 6/ rad/h, and their deterioration was tested for the items of elongation, tensile strength, resistivity, dielectric tangent and gel fraction. The aging mechanism and dose rate effect were also considered. The dose rate effect appeared or did not appear depending on the types of materials and also their properties. The materials that showed the dose rate effect included the typical ones whose characteristics degraded with the decreasing dose rate, and the peculiar ones whose deterioration of characteristics did not appear constantly. Aging mechanism may vary in the case of high dose rate and low dose rate. Also, if the life time at respective dose rate in relatively higher dose rate region is clarified, the life time in low dose rate region may possibly be predicted.

How accelerated biological aging can affect solar reflective polymeric based building materials

Science.gov (United States)

Ferrari, C.; Santunione, G.; Libbra, A.; Muscio, A.; Sgarbi, E.

2017-11-01

Among the main issues concerning building materials, in particular outdoor ones, one can identify the colonization by microorganisms referred to as biological aggression. This can affect not only the aesthetical aspect but also the thermal performance of solar reflective materials. In order to improve the reliability of tests aimed to assess the resistance to biological aggression and contextually reduce the test duration, an accelerated test method has been developed. It is based on a lab reproducible setup where specific and controlled environmental and boundary conditions are imposed to accelerate as much as possible biological growth on building materials. Due to their widespread use, polymeric materials have been selected for the present analysis, in the aim of reaching an advanced bio-aged level in a relatively short time (8 weeks or less) and at the same time comparatively evaluate different materials under a given set of ageing conditions. Surface properties before, during and after ageing have been investigated by surface, microstructural and chemical analyses, as well as by examination of time progressive images to assess bacterial and algal growth rate.

230Th-234U Model-Ages of Some Uranium Standard Reference Materials

Energy Technology Data Exchange (ETDEWEB)

Williams, R W; Gaffney, A M; Kristo, M J; Hutcheon, I D

2009-05-28

The 'age' of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to its source. To the extent that the sample obeys the standard rules of radiochronometry, then the production ages of even very recent material can be determined using the {sup 230}Th-{sup 234}U chronometer. These standard rules may be summarized as (a) the daughter/parent ratio at time=zero must be known, and (b) there has been no daughter/parent fractionation since production. For most samples of uranium, the 'ages' determined using this chronometer are semantically 'model-ages' because (a) some assumption of the initial {sup 230}Th content in the sample is required and (b) closed-system behavior is assumed. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for samples where both rules are met. The U isotopic standards have known purification and production dates, and closed-system behavior in the solid form (U{sub 3}O{sub 8}) may be assumed with confidence. We present here {sup 230}Th-{sup 234}U model-ages for several of these standards, determined by isotope dilution mass spectrometry using a multicollector ICP-MS, and compare these ages with their known production history.

The difficult issue of age assessment on pedo-pornographic material.

Science.gov (United States)

Cattaneo, Cristina; Ritz-Timme, Stefanie; Gabriel, Peter; Gibelli, Daniele; Giudici, Elena; Poppa, Pasquale; Nohrden, Doerte; Assmann, Sabine; Schmitt, Roland; Grandi, Marco

2009-01-10

The issue of juvenile pornography has seen an increase in the past few years of the number of expert opinions requested to forensic pathologists, paediatricians and other various experts within the forensic and medical fields concerning the age of represented individuals. Regardless of the entity of the problem, no actual method exists which can allow us to give an objective and scientific answer, particularly in the postpubertal stage. Using parameters related to sexual maturation can be very dangerous. Nonetheless some experts still insist with similar types of "expertises". This study aims at verifying the ability of different experts in assessing age of postpubertal individuals represented in pornographic material. Results underline the difficulties and major uncertainties of age evaluation by visual observation of photographic material particularly when the subjects have reached the sexual maturation stage - and therefore in verifying whether the individual is above or below 18 years of age (an important age limit for most European countries as far as this type of crime is concerned). Furthermore the study stresses the need both to search for an alternate approach and to apply extreme caution in judicial evaluation.

Evaluation of Proactive Management Issues Associated with Materials Aging in Light Water Reactors

International Nuclear Information System (INIS)

Shoji, T.; Takeda, Y.; Kuniya, J.

2012-01-01

A Proactive Materials Degradation Management (PMDM) project has been carried out at the Fracture Research Institute (FRI), Tohoku University for 4 years, as a part of a Nuclear Industries Safety Agency (NISA) project that was formed in 2007 to define an Aging Management Program that addresses unexpected structural material failures in Light Water Reactors (LWRs). Such a program required, therefore, the development of a life prediction capability for specific combinations of degradation modes, structural materials, and reactor components. In this paper, the research subjects needed to predict quantitatively aging degradation phenomena in LWR structural materials are introduced. (author)

Statistical models for thermal ageing of steel materials in nuclear power plants

International Nuclear Information System (INIS)

Persoz, M.

1996-01-01

Some category of steel materials in nuclear power plants may be subjected to thermal ageing, whose extent depends on the steel chemical composition and the ageing parameters, i.e. temperature and duration. This ageing affects the 'impact strength' of the materials, which is a mechanical property. In order to assess the residual lifetime of these components, a probabilistic study has been launched, which takes into account the scatter over the input parameters of the mechanical model. Predictive formulae for estimating the impact strength of aged materials are important input data of the model. A data base has been created with impact strength results obtained from an ageing program in laboratory and statistical treatments have been undertaken. Two kinds of model have been developed, with non linear regression methods (PROC NLIN, available in SAS/STAT). The first one, using a hyperbolic tangent function, is partly based on physical considerations, and the second one, of an exponential type, is purely statistically built. The difficulties consist in selecting the significant parameters and attributing initial values to the coefficients, which is a requirement of the NLIN procedure. This global statistical analysis has led to general models that are unction of the chemical variables and the ageing parameters. These models are as precise (if not more) as local models that had been developed earlier for some specific values of ageing temperature and ageing duration. This paper describes the data and the methodology used to build the models and analyses the results given by the SAS system. (author)

Feasibility Study for the Development of Plutonium Reference Materials for Age Dating in Nuclear Forensics

International Nuclear Information System (INIS)

Sturm, M.; Richter, S.; Aregbe, Y.; Wellum, R.; Altzitzoglou, T.; Verbruggen, A.; Mayer, K.; Prohaska, T.

2010-01-01

Isotopic reference materials certified for the age of nuclear material (uranium, plutonium) are needed in the fields of nuclear forensics and environmental measurements. Therefore a feasibility study for the development of plutonium reference materials for age dating has been started recently at the Institute for Reference Materials and Measurements (EC-JRC-IRMM). The ''age'' of the material is defined as the time that has passed since the last chemical separation of the mother and daughter isotopes (e.g. 241 Pu and 241 Am). Assuming that the separation has been complete and all the daughter isotopes have been removed from the original material during this last separation, the age of the material can be determined by measuring the ratio of daughter and mother radio-nuclides, e.g. 241 Am/ 241 Pu. At a given time after the last separation and depending on the half lives of the radio-nuclides involved, a certain amount of the daughter radionuclide(s) will be present. For the determination of the unknown age of a material different ''clocks'' can be used; ''clocks'' are pairs of mother and daughter radio-nuclides, such as 241 Am/ 241 Pu, 238 Pu/ 234 U, 239 Pu/ 235 U, 240 Pu/ 236 U, and possibly 242 Pu/ 238 U. For the age estimation of a real sample, such as material seized in nuclear forensics investigations or dust samples in environmental measurements, it is advisable to use more than one clock in order to ensure the reliability of the results and to exclude the possibility that the sample under question is a mixture of two or more materials. Consequently, a future reference material certified for separation date should ideally be certified for more than one ''clock'' or several reference materials for different ''clocks'' should be developed. The first step of this study is to verify the known separation dates of different plutonium materials of different ages and isotopic compositions by measuring the mother ( 238 Pu, 239 Pu, 240 Pu, 241 Pu, 242 Pu) and daughter

Aging predictions in nuclear power plants: Crosslinked polyolefin and EPR cable insulation materials

International Nuclear Information System (INIS)

Gillen, K.T.; Clough, R.L.

1991-06-01

In two earlier reports, we derived a time-temperature-dose rate superposition methodology, which, when applicable, can be used to predict cable degradation versus dose rate, temperature and exposure time. This methodology results in long-term predictive capabilities at the low dose rates appropriate to ambient nuclear power plant aging environments. The methodology was successfully applied to numerous important cable materials used in nuclear applications and the extrapolated predictions were verified by comparisons with long-term (7 to 12 year) results for similar or identical materials aged in nuclear environments. In this report, we test the methodology on three crosslinked polyolefin (CLPO) and two ethylene propylene rubber (EPR) cable insulation materials. The methodology applies to one of the CLPO materials and one of the EPR materials, allowing predictions to be made for these materials under low dose-rate, low temperature conditions. For the other materials, it is determined that, at low temperatures, a decrease in temperature at a constant radiation dose rate leads to an increase in the degradation rate for the mechanical properties. Since these results contradict the fundamental assumption underlying time-temperature-dose rate superposition, this methodology cannot be applied to such data. As indicated in the earlier reports, such anomalous results might be expected when attempting to model data taken across the crystalline melting region of semicrystalline materials. Nonetheless, the existing experimental evidence suggests that these CLPO and EPR materials have substantial aging endurance for typical reactor conditions. 28 refs., 26 figs., 3 tabs

Suitability of asthma education materials for school-age children: Implications for health literacy.

Science.gov (United States)

Tzeng, Yu-Fen; Gau, Bih-Shya

2018-03-01

To investigate the suitability of asthma education materials for school-age children with asthma and elucidate how these children used their health-literacy abilities to identify whether the materials can be accepted, comprehended and applied. Effective asthma self-management education is influenced by the suitability of materials and an individual's health literacy. A mixed-method research design was developed using quantitative and qualitative surveys. The suitability of the materials was assessed on the basis of the Chinese version of the Suitability Assessment of Materials by five experts. In addition, five school-age children (age: 8-12 years) were recruited and interviewed. In total, 25 pieces of asthma education material for children were collected. On the basis of their type, the materials were categorised as nine brochures, 11 leaflets and five videos. Of the 25 materials, 17 were rated as superior materials, whereas eight were rated as adequate materials. The suitability scores of the video-based materials were significantly higher than those of the brochures and leaflets (p = .006). One print material was considered to have a reading level suitable for fifth-grade or younger children, whereas the remaining materials were considered suitable for sixth-grade or older children. The following six health-literacy domains were identified: recognising asthma through body knowledge, posing reflective questions, identifying self-care difficulties, receiving adult guidance, learning with enjoyment and addressing learning requirements. The video-based materials had integrated content and were appealing to children. Cartoon animations, interactive computer games, and skill demonstrations may enhance learning stimulation and motivation and increase learning effects in children. The present results may help healthcare providers to understand children's capacities to manage their disease, effectively address children's requirements and function as a key resource for

Effect of artificial aging on the surface roughness and microhardness of resin-based materials.

Science.gov (United States)

Santos, M Jacinta M C; Rêgo, Heleine Maria Chagas; Mukhopadhyay, Anuradha; El Najjar, Mai; Santos, Gildo C

2016-01-01

This study sought to verify the effects of aging on the surface roughness (Ra) and microhardness (Knoop hardness number [KHN]) of resin-based restorative materials protected with a surface sealer. Disc specimens of 2 resin-modified glass ionomers (RMGIs) and 1 composite resin (CR) were fabricated in a metal mold. Specimens of each material were divided into 1 group that was covered with surface sealer and 1 group that was not. Both groups of each material were then subdivided according to whether they were stored (aged) in cola or distilled water. Surface roughness and KHN values were obtained from each specimen before and after storage. After aging of the specimens, significantly higher Ra values were observed in the 2 RMGIs when they were not covered with a surface sealer, while the CR was not affected. The KHN values varied by materials and storage conditions (with and without a surface sealer). All the groups with a surface sealer exhibited increased Ra values after aging.

Knowledge of ageing phenomenons of materials used in the PWR power plants

International Nuclear Information System (INIS)

Vancon, D.; Meyzaud, Y.; Soulat, P.

1996-01-01

The nuclear power plants with PWR type reactors are planned to work during forty years and are the subject of studies aiming to check their integrity during all their life. The materials used to the fabrication of the components can be submitted different stress. The temperature, the mechanical constraints, the irradiation are examples of stress which can make the materials getting old. This text presents three themes: the ageing by irradiation, the thermal ageing and the corrosion, and their principle industrial consequences. (N.C.)

Does artificial aging affect mechanical properties of CAD/CAM composite materials.

Science.gov (United States)

Egilmez, Ferhan; Ergun, Gulfem; Cekic-Nagas, Isil; Vallittu, Pekka K; Lassila, Lippo V J

2018-01-01

The purpose of this study was to determine the flexural strength and Weibull characteristics of different CAD/CAM materials after different in vitro aging conditions. The specimens were randomly assigned to one of the six in vitro aging conditions: (1) water storage (37°C, 3 weeks), (2) boiling water (24h), (3) hydrochloric acid exposure (pH: 1.2, 24h), (4) autoclave treatment (134°C, 200kPa, 12h), (5) thermal cycling (5000 times, 5-55°C), (6) cyclic loading (100N, 50,000 cycles). No treatment was applied to the specimens in control group. Three-point bending test was used for the calculation of flexural strength. The reliability of the strength was assessed by Weibull distribution. Surface roughness and topography was examined by coherence scanning interferometry. Evaluated parameters were compared using the Kruskall-Wallis or Mann-Whitney U test. Water storage, autoclave treatment and thermal cycling significantly decreased the flexural strength of all materials (p0.05). Weibull moduli of Cerasmart™ and Lava™ Ultimate were similar with control. Vita Enamic ® exhibited similar Weibull moduli in all aging groups except the HCl treated group (p>0.05). R a values of Cerasmart™ and Lava™ Ultimate were in the range of 0.053-0.088μm in the aged groups. However R a results of Vita Enamic ® were larger than 0.2μm. Flexural strength of newly developed restorative CAD/CAM materials was significantly decreased by artificial aging. Cyclic loading or HCl exposure does not affect to the flexural strength and structural reliability of Cerasmart™ and Lava™ Ultimate. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Proceedings of the international workshop on aged and decommissioned material collection and testing for structural integrity purposes

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-07-01

This workshop was sponsored by the CEC DG XI and XII/JRC Petten/AMES and by the Principal Working Group 3 (PWG-3) on reactor component integrity of the NEA CSNI, and it was hosted by the CEN Mol, Belgium. The activities of PWG-3 fall into three main areas: non-destructive examination (NDE), fracture analysis, and ageing/materials degradation. The topic of the workshop falls into the third area of ageing and materials degradation. The titles of the papers are: AMES and other European networks in Integrity of Ageing Structures; Over View of Proving Test on the Reliability of Material of Nuclear Power Plant Components; Activities on Ageing Degradation Phenomena of NPP in Korea; Capability of Investigation on Decommissioned Parts from NPPs at the MPA Stuttgart; How Accurately can Surveillance Specimens Reflect the True State of RPV Materials?; Applicability of Design Codes to Aged Materials; Microstructural Investigations of as-Fabricated, Long-Term Thermally Aged and Neutron Irradiated RPV Materials: An Atom Probe Study; Proposed Post-Service Investigations on Decommissioned Greifswald Units; Tools and Experience in Post Irradiation Examination of Structural Core Components at PSI Hot laboratory; Testing of Beznau NPP Unit 1 Steam Generator Cast Stainless Steel Elbows; Mechanical Properties Characterisation of Irradiated Materials From Operating or Decommissioned Nuclear Power Plants; Long Term Ageing of Cast Ti-Stabilised Stainless Steel; Enhanced Surveillance of Nuclear Reactor Pressure Vessels. Discussions and conclusions are also presented

The Influence of Aging Period, Freezing Temperature and Packaging Material on Frozen Beef Chemical Quality

Directory of Open Access Journals (Sweden)

Aris Sri Widati

2012-04-01

Full Text Available The objective of the study was to evaluate the influences of aging period, freezing temperature and packaging material on the frozen beef chemical quality. The material of the study was 2-3 years old Ongole grade beef of the Longissimus dorsi part,  and was then classified into 3 treat­ments, namely A (aging periode; 0, 12 and 24 hours, B (freezing temperature; -10°C and -20°C and C (packaging material; aluminum foil (Al, polyprophylene (PP, poly­ethylene (PE and without packaging material. The ob­served variables were water content, crude protein, fat, ash content. The data were analyzed by the Completely Randomized Design (CRD in the Factorial (3x2x4 pattern. The results indicated that the aging periode de­creased the water content, and ash content significantly (P<0.05, and decreased the crude protein but increased the fat content insignificantly. The lower freezing temperature prevented the decreases of the water content, and ash content significantly (P<0.05, but prevented the decrease of crude protein, fat content insignificantly. The packaging material could prevent the decreases of water content, ash content sig­nificantly (P<0.05, but prevent the decreases of protein, and fat content insignificantly. A significant interaction (P<0.05 occured between the freezing temperature and packaging material factors on ash content of the frozen beef. The conclusion was the frozen beef without aging has a high of water content, protein, and ash, but has a low fat content.Temperature at -200C and using aluminium foil packaging can prevent decreasing quality of frozen beef. Keywords : Aging period, freezing temperature,  packaging material

Simulated Aging of Spacecraft External Materials on Orbit

Science.gov (United States)

Khatipov, S.

Moscow State Engineering Physics Institute (MIFI), in cooperation with Air Force Research Laboratory's Satellite Assessment Center (SatAC), the European Office of Aerospace Research and Development (EOARD), and the International Science and Technology Center (ISTC), has developed a database describing the changes in optical properties of materials used on the external surfaces of spacecraft due to space environmental factors. The database includes data acquired from tests completed under contract with the ISTC and EOARD, as well as from previous Russian materials studies conducted within the last 30 years. The space environmental factors studied are for those found in Low Earth Orbits (LEO) and Geosynchronous orbits (GEO), including electron irradiation at 50, 100, and 200 keV, proton irradiation at 50, 150, 300, and 500 keV, and ultraviolet irradiation equivalent to 1 sun-year. The material characteristics investigated were solar absorption (aS), spectral reflectance (rl), solar reflectance (rS), emissivity (e), spectral transmission coefficient (Tl), solar transmittance (TS), optical density (D), relative optical density (D/x), Bi-directional Reflectance Distribution Function (BRDF), and change of appearance and color in the visible wavelengths. The materials tested in the project were thermal control coatings (paints), multilayer insulation (films), and solar cells. The ability to predict changes in optical properties of spacecraft materials is important to increase the fidelity of space observation tools, better understand observation of space objects, and increase the longevity of spacecraft. The end goal of our project is to build semi-empirical mathematical models to predict the long-term effects of space aging as a function of time and orbit.

[Problems associated with age estimation of underage persons who appear in child pornography materials].

Science.gov (United States)

Łabecka, Marzena; Lorkiewicz-Muszyńska, Dorota; Jarzabek-Bielecka, Grazyna

2011-01-01

Among opinions issued by the Forensic Medicine Department, Medical Science University in Poznan, in the last six years, there are opinions concerning age estimation in child pornography materials. The issue subject to research is indicating persons under the age of 15 years in pornographic materials, since possession of pornographic materials featuring underage persons is considered a crime and is subject to article 202 of the Penal Code. The estimation of the age of teenagers based on secondary and tertiary sexual characteristics is increasingly more difficult and the available data in professional literature regarding the standard time of development differ among various authors of such studies. In the report, an attempt has been made at determining the agreement regarding different characteristics in the data included in the Tanner's scale, which has been modified to accommodate the research done on persons registered by electronic means. The modified scale, which up to now has been used in research of registered subjects in classified public prosecutors' materials, has been employed in children seen in a pediatric outpatient department. The goal has been a comparison of the outcome of the research to prove its usefulness so that in the future, the modified scale could be used as a research tool in estimation of age of persons appearing in pornography materials. medical forms of 205 children seen in a pediatric outpatient department, based on the scale created by the present authors us and later processed using Excel.

Aging linear viscoelasticity of matrix-inclusion composite materials featuring ellipsoidal inclusions

OpenAIRE

LAVERGNE, Francis; SAB, Karam; SANAHUJA, Julien; BORNERT, Michel; TOULEMONDE, Charles

2016-01-01

A multi-scale homogenization scheme is proposed to estimate the time-dependent strains of fiber-reinforced concrete. This material is modeled as an aging linear viscoelastic composite material featuring ellipsoidal inclusions embedded in a viscoelastic cementitious matrix characterized by a time-dependent Poisson's ratio. To this end, the homogenization scheme proposed in Lavergne et al. [1] is adapted to the case of a time-dependent Poisson's ratio and it is successfully validated on a non-a...

Proactive materials aging management and multi-layered maintenance

International Nuclear Information System (INIS)

Shoji, Tetsuo

2009-01-01

Long term operation of NPP has been receiving a great concern based upon the plant operation experiences and progressive improvement in countermeasures and mitigations. At the same time of this LTO movement, proactive materials aging management is also receiving a great concern to realize the LTO in NPP. Recent PMDM activities in Japan as well as some international one are reviewed and a necessity of an international cooperation is emphasized in relation to reliable maintenance performance connected from the top of the organization to operators and maintenance engineers at plant sites. (author)

Experimental characterization of thermal and hygric properties of hemp concrete with consideration of the material age evolution

Science.gov (United States)

Bennai, F.; Issaadi, N.; Abahri, K.; Belarbi, R.; Tahakourt, A.

2018-04-01

The incorporation of plant crops in construction materials offers very good hygrothermal performance to the building, ensuring substantial environmental and ecological benefits. This paper focuses on studying the evolution of hygrothermal properties of hemp concrete over age (7, 30 and 60 days). The analysis is done with respect to two main hygric and thermal properties, respectively: sorption isotherms, water vapor permeability, thermal conductivity and heat capacity. In fact, most of these parameters are very susceptible to change function of the age of the material. This influence of the aging is mainly due to the evolution of the microstructure with the binder hydration over time and the creation of new hydrates which can reduces the porosity of the material and consequently modify its properties. All the tested hemp concrete samples presented high moisture storage capacity and high-water vapor permeability whatever the age of such hygroscopic material. These hygric parameters increase significantly for high relative humidity requiring more consideration of such variability during the modeling of coupled heat and mass transfer within the material. By the same, the thermal conductivity and heat capacity tests highlighted the impact of the temperature and hygric state of the studied material.

Electrochemical migration technique to accelerate ageing of cementitious materials

Directory of Open Access Journals (Sweden)

Abbas Z.

2013-07-01

Full Text Available Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen’s micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.

Electrochemical migration technique to accelerate ageing of cementitious materials

Science.gov (United States)

Babaahmadi, A.; Tang, L.; Abbas, Z.

2013-07-01

Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW) takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen's micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.

Measurement of volume change in cementitious materials at early ages - Review of testing protocols and interpretation of results

DEFF Research Database (Denmark)

Sant, Gaurav; Lura, Pietro; Weiss, Jason

2006-01-01

Early-age cracking in concrete bridge decks, pavements, and superstructure elements has served as the impetus for substantial research on early-age shrinkage in cementitious materials. Much of this research has indicated how mixture proportions, constituent materials, and construction operations...

Nb-base FS-85 Alloy as a Candidate Structural Material for Space Reactor Applications: Effects of Thermal Aging

International Nuclear Information System (INIS)

Leonard, Keith J.; Busby, Jeremy T.; Hoelzer, David T.; Zinkle, Steven J.

2009-01-01

The proposed use of fission reactors for manned or deep space missions have typically relied on the potential use of refractory metal alloys as structural materials. Throughout the history of these programs, the lead candidate has been Nb-1Zr due to its good fabrication and welding characteristics. However, the less than optimal creep resistance of this alloy has encouraged interest in the more complex FS-85 (Nb-28Ta-10W-1Zr) alloy. Despite this interest, a relatively small database exists for the properties of FS-85. These gaps include potential microstructural instabilities that can lead to mechanical property degradation. In this work, changes in microstructure and mechanical properties of FS-85 were investigated following 1100 h of thermal aging at 1098, 1248 and 1398 K. The changes in electrical resistivity, hardness and tensile properties between the as-annealed and aged materials are compared. Evaluation of the microstructural changes was performed through optical, scanning and transmission electron microscopy. The development of intragranular and grain boundary precipitation of Zr-rich compounds as a function of aging temperature was followed. Brittle tensile behavior was measured in the 1248 K aged material, while ductile behavior occurred in material aged above and below this temperature. The effect of temperature on the under and overaging of the grain boundary particles are believed to have contributed to the mechanical property behavior of the aged material

A Study on Accelerated Thermal Aging of High Modulus Carbon/Epoxy Composite Material

Directory of Open Access Journals (Sweden)

Ju Min Kyung

2015-01-01

Full Text Available Composite materials have been used increasingly for various space applications due to the favorable characteristic of high modulus to density ratio and potential for near-zero coefficient of thermal expansion. In composite system, depending on the orientation of fibers, strength and stiffness can be changed so that the optimum structure can be accomplished. This is because the coefficient of thermal expansion (CTE of carbon fibers is negative. For spacecraft and orbiting space structure, which are thermally cycled by moving through the earth' shadow for at least 5 years, it is necessary to investigate the change of properties of the material over time. In this study, thermal aging of epoxy matrix/high modulus carbon fiber composite materials are accelerated to predict the long term creep property. Specimens are tested at various temperatures of 100~140°C with dynamic mechanical analysis to obtain creep compliances that are functions of time and temperature. Using Time Temperature Superposition method, creep compliance curves at each temperature are shifted to the reference temperature by shift factor and a master curve is generated at the reference temperature. This information is useful to predict the long term thermal aging of high modulus composite material for spacecraft application.

First Exploratory Study on the Ageing of Rammed Earth Material

Science.gov (United States)

Bui, Quoc-Bao; Morel, Jean-Claude

2014-01-01

Rammed earth (RE) is attracting renewed interest throughout the world thanks to its “green” characteristics in the context of sustainable building. In this study, the ageing effects on RE material are studied on the walls which have been constructed and exposed for 22 years to natural weathering. First, mechanical characteristics of the “old” walls were determined by two approaches: in-situ dynamic measurements on the walls; laboratory tests on specimens which had been cut from the walls. Then, the walls’ soil was recycled and reused for manufacturing of new specimens which represented the initial state. Comparison between the compressive strength, the Young modulus of the walls after 22 years on site and that of the initial state enables to assess the ageing of the studied walls. PMID:28787920

Assessment of Aging of Cork and TISAF Materials in the SAFKEG 3940A Package in KAMS

International Nuclear Information System (INIS)

Vormelker, P.R.

2003-01-01

This report provides an assessment of the potential for aging and degradation of the resin-bonded cork and the Thermal-Insulating, Shock-Absorbing Foam materials that are components of the SAFKEG 3940A package. This package may be used for interim storage of plutonium materials in the Savannah River Site K-Area Materials Storage

Grinding With Diamond Burs and Hydrothermal Aging of a Y-TZP Material: Effect on the Material Surface Characteristics and Bacterial Adhesion.

Science.gov (United States)

Dutra, Dam; Pereira, Gkr; Kantorski, K Z; Exterkate, Ram; Kleverlaan, C J; Valandro, L F; Zanatta, F B

The aim of this study was to evaluate the effect of grinding with diamond burs and low-temperature aging on the material surface characteristics and bacteria adhesion on a yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) surface. Y-TZP specimens were made from presintered blocks, sintered as recommended by the manufacturer, and assigned into six groups according to two factors-grinding (three levels: as sintered, grinding with extra-fine diamond bur [25-μm grit], and grinding with coarse diamond bur [181-μm grit]) and hydrothermal aging-to promote low-temperature degradation (two levels: presence/absence). Phase transformation (X-ray diffractometer), surface roughness, micromorphological patterns (atomic force microscopy), and contact angle (goniometer) were analyzed. Bacterial adhesion (colony-forming units [CFU]/biofilm) was quantified using an in vitro polymicrobial biofilm model. Both the surface treatment and hydrothermal aging promoted an increase in m-phase content. Roughness values increased as a function of increasing bur grit sizes. Grinding with a coarse diamond bur resulted in significantly lower values of contact angle (p0.05). Grinding with diamond burs and hydrothermal aging modified the Y-TZP surface properties; however, these properties had no effect on the amount of bacteria adhesion on the material surface.

Aging Mechanisms of Electrode Materials in Lithium-Ion Batteries for Electric Vehicles

Directory of Open Access Journals (Sweden)

Cheng Lin

2015-01-01

Full Text Available Electrode material aging leads to a decrease in capacity and/or a rise in resistance of the whole cell and thus can dramatically affect the performance of lithium-ion batteries. Furthermore, the aging phenomena are extremely complicated to describe due to the coupling of various factors. In this review, we give an interpretation of capacity/power fading of electrode-oriented aging mechanisms under cycling and various storage conditions for metallic oxide-based cathodes and carbon-based anodes. For the cathode of lithium-ion batteries, the mechanical stress and strain resulting from the lithium ions insertion and extraction predominantly lead to structural disordering. Another important aging mechanism is the metal dissolution from the cathode and the subsequent deposition on the anode. For the anode, the main aging mechanisms are the loss of recyclable lithium ions caused by the formation and increasing growth of a solid electrolyte interphase (SEI and the mechanical fatigue caused by the diffusion-induced stress on the carbon anode particles. Additionally, electrode aging largely depends on the electrochemical behaviour under cycling and storage conditions and results from both structural/morphological changes and side reactions aggravated by decomposition products and protic impurities in the electrolyte.

Episodic encoding in normal aging: attentional resources hypothesis extended to musical material.

Science.gov (United States)

Blanchet, Sophie; Belleville, Sylvie; Peretz, Isabelle

2006-01-01

The goal of the present study was to examine age-related changes in musical episodic memory for novel tunes. This was conducted by manipulating the encoding condition in a recognition paradigm. After receiving memory instructions (intentional condition), older and younger participants obtained equivalent hits. In contrast, when intentional encoding was accompanied by a dancing judgment (dancing + intentional condition), the recognition performance of the older persons was severely impaired. Impaired recognition was also found when participants only judged the excerpts without being instructed to memorize them (dancing judgment condition). Although older participants demonstrated a preserved ability to perform the dancing judgment on its own, this ability was not optimal and likely precluded the initiation of more elaborate encoding strategies. These results suggest that asking older persons to divide their attention in the study phase reduces the quality of their musical encoding. Given this extension to musical material, we discuss the notion that the age-related attentional resource decline appears to be domain-general rather than specific to verbal material.

Evaluation of thermal aging effect on primary pipe material in nuclear power plant by micro hardness test method

International Nuclear Information System (INIS)

Xue Fei; Yu Weiwei; Wang Zhaoxi; Ma Qinzheng; Liu Wei

2012-01-01

The investigation was carried out on the changes in mechanical properties of the primary pipe material Z3CN20.09M after 10000 h aging at 400℃ by using micro- Vickers and impact testing machine. The results show that the impact energy of testing material decreases. However, the micro-Vickers hardness of ferrite phase and austenite phase which constitute the testing material increase and keep constant, respectively. The intrinsic relations were analyzed between the micro-Vickers hardness and the impact energy to make an attempt to present the micro-Vickers hardness measurement as a method applicable to evaluating the thermal aging of the primary pipe material. (authors)

Color stability of sealed composite resin restorative materials after ultraviolet artificial aging and immersion in staining solutions.

Science.gov (United States)

Catelan, Anderson; Briso, André Luiz Fraga; Sundfeld, Renato Hermann; Goiato, Marcelo Coelho; dos Santos, Paulo Henrique

2011-04-01

The color alteration of resin-based materials is one of the most common reasons to replace esthetic dental restorations. This study assessed the influence of surface sealant (Biscover) on the color stability of nanofilled (Supreme XT) and microhybrid (Vit-l-escence and Opallis) composite resins after artificial aging. One hundred disc-shaped (6 × 1.5 mm) specimens were made for each composite resin. After 24 hours, all specimens were polished and sealant was applied to 50 specimens of each material. Baseline color was measured according to the CIE L*a*b* system using a reflection spectrophotometer. Ten specimens of each group were aged for 252 h in an ultraviolet (UV)-accelerated aging chamber or immersed for 4 weeks in cola soft drink, orange juice, red wine staining solutions or distilled water as control. Color difference (ΔE) after aging was calculated based on the color coordinates before (baseline) and after aging/staining treatment. Data were analyzed with 2-way ANOVA and Fisher's test (α=.05). The results showed significant changes in color after artificial aging in all the groups (Paging, and the cola soft drink. The lowest values of ΔE were found for specimens stored in distilled water. All composite resins showed some color alteration after the aging methods. The surface sealant did not alter the color stability of the tested materials. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Nb-Base FS-85 Alloy as a Candidate Structural Material for Space Reactor Applications: Effects of Thermal Aging

Science.gov (United States)

Leonard, Keith J.; Busby, Jeremy T.; Hoelzer, David T.; Zinkle, Steven J.

2009-04-01

The proposed uses of fission reactors for manned or deep space missions have typically relied on the potential use of refractory metal alloys as structural materials. Throughout the history of these programs, a leading candidate has been Nb-1Zr, due to its good fabrication and welding characteristics. However, the less-than-optimal creep resistance of this alloy has encouraged interest in the more complex FS-85 (Nb-28Ta-10W-1Zr) alloy. Despite this interest, only a relatively small database exists for the properties of FS-85. Database gaps include the potential microstructural instabilities that can lead to mechanical property degradation. In this work, changes in the microstructure and mechanical properties of FS-85 were investigated following 1100 hours of thermal aging at 1098, 1248, and 1398 K. The changes in electrical resistivity, hardness, and tensile properties between the as-annealed and aged materials are compared. Evaluation of the microstructural changes was performed through optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The development of intragranular and grain-boundary precipitation of Zr-rich compounds as a function of aging temperature was followed. Brittle tensile behavior was measured in the material aged at 1248 K, while ductile behavior occurred in samples aged above and below this temperature. The effect of temperature on the under- and overaging of the grain-boundary particles is believed to have contributed to the mechanical property behavior of the aged materials.

Accelerated Aging Effect on Epoxy-polysiloxane Polymeric Insulator Material with Rice Husk Ash Filler

Directory of Open Access Journals (Sweden)

Rochmadi .

2012-12-01

Full Text Available The performances of outdoor polymeric insulators are influenced by environmental conditions. This paper presents the effect of artificial tropical climate on the hydrophobicity, equivalent salt deposit density (ESDD, surface leakage current, flashover voltage, and surface degradation on epoxy-polysiloxane polymeric insulator materials with rice husk ash (RHA. Test samples are made at room temperature vulcanized (RTV of various composition of epoxy-polysiloxane with rice husk ash as filler. The aging was carried out in test chamber at temperature from 50oC to 62oC, relative humidity of 60% to 80%, and ultraviolet (UV  radiation 21.28 w/cm2 in daylight conditions for 96 hours. The experiment results showed that the flashover voltage fluctuates from 34.13 kV up to 40.92 kV and tends to decrease on each variation of material composition. The surface leakage current fluctuates and tends to increase. Test samples with higher filler content result greater hydrophobicity, smaller equivalent salt deposit density, and smaller critical leakage current, which caused the increase of the flashover voltage. Insulator material (RTVEP3 showed the best performance in tropical climate environment. Artificial tropical aging for short duration gives less effect to the surface degradation of epoxy-polysiloxane insulator material.

Ageing studies on materials, components and process instruments used in nuclear power plants

International Nuclear Information System (INIS)

Bora, J.S.

1997-04-01

This report is a compilation of test results of thermal and radiation ageing tests carried out in the laboratory over a period of 25 years on diverse engineering materials, components and instruments used in nuclear power plants. Test items covered are different types of electrical cables, elastomers, surface coatings, electrical and electronics components and process instruments. Effects of thermal and radiation ageing on performance parameters are shown in tabular forms. Apart from finding the characteristics, capabilities and limitations of test items, ageing research has helped in pin-pointing sub-standard and critical parts and necessary corrective action has been taken. This report is expected to be quite useful to the manufacturers users and researchers for reference and guidance. (author)

All the things I have - handling one's material room in old age.

Science.gov (United States)

Larsson Ranada, Asa; Hagberg, Jan-Erik

2014-12-01

The article explores how old people who live in their ordinary home, reason and act regarding their 'material room' (technical objects, such as household appliances, communication tools and things, such as furniture, personal belongings, gadgets, books, paintings, and memorabilia). The interest is in how they, as a consequence of their aging, look at acquiring new objects and phasing out older objects from the home. This is a broader approach than in most other studies of how old people relate to materiality in which attention is mostly paid either to adjustments to the physical environment or to the importance of personal possessions. In the latter cases, the focus is on downsizing processes (e.g. household disbandment or casser maison) in connection with a move to smaller accommodation or to a nursing home. The article is based on a study in which thirteen older people (median age 87), living in a Swedish town of medium size were interviewed (2012) for a third time. The questions concerned the need and desire for new objects, replacement of broken objects, sorting out the home or elsewhere, most cherished possessions, and the role of family members such as children and grandchildren. The results reveal the complexity of how one handles the material room. Most evident is the participants' reluctance to acquire new objects or even to replace broken things. Nearly all of them had considered, but few had started, a process of sorting out objects. These standpoints in combination resulted in a relatively intact material room, which was motivated by an ambition to simplify daily life or to facilitate the approaching dissolution of the home. Some objects of special value and other cherished objects materialized the connections between generations within a family. Some participants wanted to spare their children the burden of having to decide on what to do with their possessions. Others (mostly men), on the contrary, relied on their children to do the sorting out after

Materials compatibility and aging for flux and cleaner combinations

Energy Technology Data Exchange (ETDEWEB)

Archuleta, Kim M. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Piatt, Rochelle [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-01-01

A materials study of high reliability electronics cleaning is presented here. In Phase 1, mixed type substrates underwent a condensed contaminants application to view a worst- case scenario for unremoved flux with cleaning agent residue for parts in a silicone oil filled environment. In Phase 2, fluxes applied to copper coupons and to printed wiring boards underwent gentle cleaning then accelerated aging in air at 65% humidity and 30 O C. Both sets were aged for 4 weeks. Contaminants were no-clean (ORL0), water soluble (ORH1 liquid and ORH0 paste), and rosin (RMA; ROL0) fluxes. Defluxing agents were water, solvents, and engineered aqueous defluxers. In the first phase, coupons had flux applied and heated, then were placed in vials of oil with a small amount of cleaning agent and additional coupons. In the second phase, pairs of copper coupons and PWB were hand soldered by application of each flux, using tin-lead solder in a strip across the coupon or a set of test components on the PWB. One of each pair was cleaned in each cleaning agent, the first with a typical clean, and the second with a brief clean. Ionic contamination residue was measured before accelerated aging. After aging, substrates were removed and a visual record of coupon damage made, from which a subjective rank was applied for comparison between the various flux and defluxer combinations; more corrosion equated to higher rank. The ORH1 water soluble flux resulted in the highest ranking in both phases, the RMA flux the least. For the first phase, in which flux and defluxer remained on coupons, the aqueous defluxers led to worse corrosion. The vapor phase cleaning agents resulted in the highest ranking in the second phase, in which there was no physical cleaning. Further study of cleaning and rinsing parameters will be required.

Intelligent material systems - The dawn of a new materials age

International Nuclear Information System (INIS)

Rogers, C.A.

1993-01-01

The intelligent material system solution to such engineering problems as the design of a robotic arm borrows directly from biological analogs; materials that behave much as muscles do during contraction can be employed as induced strain actuators which work against the intrinsic structural impedance of the component. Unlike actual human arms, which are jointed, the intelligent structure may be a continuum. The adaptation of structural impedance may be regarded as the most fundamental and consequential concept in the field of intelligent material systems

Materials science in the information age

Energy Technology Data Exchange (ETDEWEB)

Schwartz, L.H.; Glotzer, S.C.; Hall, D.E.; Roosen, A.R.; Warren, J.A.

1996-12-31

The explosive growth of the Internet and the World Wide Web is revolutionizing society be, making information accessible in new ways to People in all corners of the world. In scientific research, these advances in information technology have led to new methods of collaboration that overcome geographic limitations and allow researchers to exchange information in ways that were not previously possible. Materials researchers in particular now easily work with each other in remote collaborations, sharing videos, sound, graphics, and text with colleagues on the World Wide Web. Moreover, recent gains in computing power and corresponding reductions in cost have led to the widespread use of computational techniques to solve materials research problems, allowing researchers to predict materials properties and behavior over the entire range of length scales of interest, from atomic interactions to bulk materials properties. New {open_quotes}virtual{close_quotes} organizations have been created in the US to provide an infrastructure and support to researchers who are using new communication and computational tools in a variety of disciplines. We will describe the recent advances in information technology that are driving the revolution in materials research in particular, and discuss how virtual, electronically-connected organizations that bring together materials researchers with diverse talents in international, multilateral collaborations will change the paradigm of science research beyond the year 2000. 14 refs.

Aging material evaluation and studies by non-destructive techniques (AMES-NDT) - a European network project

International Nuclear Information System (INIS)

Dobmann, Gerd; Debarberis, Luigi; Coste, Jean-Francois

2001-01-01

This paper presents results obtained in a round-robin action organized in a concerted action of ten partners in the EURATOM program of the European Community. The objective of the research was to document the state of the art of available non-destructive testing (NDT) techniques in order to characterize material aging phenomena based on a reduction of Charpy-V energy and a shift in the fracture appearance transition temperature. Therefore, samples from the Japanese nuclear reactor pressure vessel JRQ-steel (ASMT Standard A533-B Class 1) have been thermally treated at 700 deg. C for 18 h with a subsequent water quenching. Besides micromagnetic and electromagnetic NDT, the positron annihilation technique, ultrasonic reverberation by using Laser ultrasonics and the thermo-electrical power have been applied to characterize the aged material states

Temperature and humidity effect on aging of silicone rubbers as sealing materials for proton exchange membrane fuel cell applications

International Nuclear Information System (INIS)

Chang, Huawei; Wan, Zhongmin; Chen, Xi; Wan, Junhua; Luo, Liang; Zhang, Haining; Shu, Shuiming; Tu, Zhengkai

2016-01-01

Highlights: • Aging of silicone rubbers with different hardness was investigated. • Existed water molecules from humidified gases can accelerate the aging process. • Silicone rubber with hardness of 40 is more suitable as sealing materials. • Silicone rubbers can be used as sealing materials below 80 °C but not above 100 °C. - Abstract: Durability and reliability of seals around perimeter of each unit are critical to the lifetime of proton exchange membrane fuel cells. In this study, we investigate the aging of silicone rubbers with different hardness, often used as sealing materials for fuel cells, subjected to dry and humidified air at different temperatures. The aging properties are characterized by variation of permanent compression set value under compression, mechanical properties, and surface morphology as well. The results show that aging of silicone rubbers becomes more severe with the increase in subjected temperature. At temperature above 100 °C, silicone rubbers are not suitable for fuel cell applications. The existed water molecules from humidified gases can accelerate the aging of silicone rubbers. Among the tested samples, silicone rubber with hardness of 40 is more durable than that with hardness of 30 and 50 for fuel cells. The change of chemical structure after aging suggests that the aging of silicone rubbers mainly results from the chemical decomposition of cross-linker units for connection of polysiloxane backbones and of methyl groups attached to silicon atoms.

Difference in radiocarbon ages of carbonized material from the inner and outer surfaces of pottery from a wetland archaeological site.

Science.gov (United States)

Miyata, Yoshiki; Minami, Masayo; Onbe, Shin; Sakamoto, Minoru; Matsuzaki, Hiroyuki; Nakamura, Toshio; Imamura, Mineo

2011-01-01

AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 (14)C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis.

Toxicity Determinations for Five Energetic Materials, Weathered and Aged in Soil, to the Collembolan Folsomia Candida

Science.gov (United States)

2015-03-01

obtained from the Soil Fauna and Ecotoxicology Research Unit, Department of Terrestrial Ecology, National Environmental Research Institute (Silkeborg...AND AGED IN SOIL , TO THE COLLEMBOLAN FOLSOMIA CANDIDA ECBC-TR-1273 Carlton T. Phillips Ronald T. Checkai Roman G. Kuperman Michael Simini...for Five Energetic Materials, Weathered and Aged in Soil , to the Collembolan Folsomia candida 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

Sixth Status Report: Testing of Aged Softwood Fiberboard Material for the 9975 Shipping Package

Energy Technology Data Exchange (ETDEWEB)

Daugherty, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-03-31

Samples have been prepared from several 9975 lower fiberboard subassemblies fabricated from softwood fiberboard. Physical, mechanical and thermal properties have been measured following varying periods of conditioning in each of several environments. These tests have been conducted in the same manner as previous testing on cane fiberboard samples. Overall, similar aging trends are observed for softwood and cane fiberboard samples, with a few differences. Some softwood fiberboard properties tend to degrade faster in some environments, while some cane fiberboard properties degrade faster in the two most aggressive environments. As a result, it is premature to assume both materials will age at the same rates, and the preliminary aging models developed for cane fiberboard might not apply to softwood fiberboard. However, it is expected that both cane and softwood fiberboard assemblies will perform satisfactorily in conforming packages stored in a typical KAC storage environment for up to 15 years. Samples from an additional 3 softwood fiberboard assemblies have begun aging during the past year to provide information on the variability of softwood fiberboard behavior. Aging and testing of softwood fiberboard will continue and additional data will be collected to support development of an aging model specific to softwood fiberboard.

Iron Age Material Culture in South Asia – Analysis and Context of Recently Discovered Slag Sites in Northwest Kashmir (Baramulla District in India

Directory of Open Access Journals (Sweden)

Mumtaz A Yatoo

2015-03-01

Full Text Available This paper deals with presence or absence of Iron Age material culture and explores the development of Iron Age in northwest Kashmir (Baramulla District. It has been noted from the previous surveys that a chronological gap existed (c. 1000 BCE – 100 CE, which roughly equates to the Iron Age in Kashmir (Yatoo 2005; Yatoo 2012. Furthermore, considering that there is very little evidence of Iron Age material culture from the few excavated (or explored sites in Kashmir, there is a debate about the very presence of Iron Age in Kashmir. The little information we have about Iron Age material culture from key sites in Kashmir (such as a few sherds of NBPW, some iron artefacts and slag at one site, has been largely dismissed as imports and lacked serious attention by scholars. It was therefore difficult to build any comparisons in the material culture for the present study. Instead the Iron Age material culture in other parts of South Asia, such as the Indian plains and northern regions of Pakistan, are discussed, as these regions have documented evidence of iron and its associated material culture but very few have archaeometallurgical evidence. Furthermore, Kashmir historically had communication links with these regions in South Asia since the early third millennium BCE until the 10th century CE, so we might expect some contact during the period of early iron production and use. Therefore, one key issue for archaeology in northwest Kashmir in this paper is to understand the link between the newly discovered slag and tuyeres with the key sites in Kashmir and in South Asia; and a further key issue is to determine whether or not there was a distinct Iron Age in north west Kashmir (or whole of Kashmir, or whether the few recovered iron artefacts from key sites of Kashmir are indeed all imports.

Failure of structural elements made of polymer supported composite materials during the multiyear natural aging

Science.gov (United States)

Blinkov, Pavel; Ogorodov, Leonid; Grabovyy, Peter

2018-03-01

Modern high-rise construction introduces a number of limitations and tasks. In addition to durability, comfort and profitability, projects should take into account energy efficiency and environmental problems. Polymer building materials are used as substitutes for materials such as brick, concrete, metal, wood and glass, and in addition to traditional materials. Plastic materials are light, can be formed into complex shapes, durable and low, and also possess a wide range of properties. Plastic materials are available in various forms, colors and textures and require minimal or no color. They are resistant to heat transfer and diffusion of moisture and do not suffer from metal corrosion or microbial attack. Polymeric materials, including thermoplastics, thermoset materials and wood-polymer composites, have many structural and non-structural applications in the construction industry. They provide unique and innovative solutions at a low cost, and their use is likely to grow in the future. A number of polymer composite materials form complex material compositions, which are applied in the construction in order to analyze the processes of damage accumulation under the conditions of complex nonstationary loading modes, and to determine the life of structural elements considering the material aging. This paper present the results of tests on short-term compression loading with a deformation rate of v = 2 mm/min using composite samples of various shapes and sizes.

LEVERAGING AGING MATERIALS DATA TO SUPPORT EXTENSION OF TRANSPORTATION SHIPPING PACKAGES SERVICE LIFE

Energy Technology Data Exchange (ETDEWEB)

Dunn, K. [Savannah River National Laboratory; Bellamy, S. [Savannah River National Laboratory; Daugherty, W. [Savannah River National Laboratory; Sindelar, R. [Savannah River National Laboratory; Skidmore, E. [Savannah River National Laboratory

2013-08-18

Nuclear material inventories are increasingly being transferred to interim storage locations where they may reside for extended periods of time. Use of a shipping package to store nuclear materials after the transfer has become more common for a variety of reasons. Shipping packages are robust and have a qualified pedigree for performance in normal operation and accident conditions but are only certified over an approved transportation window. The continued use of shipping packages to contain nuclear material during interim storage will result in reduced overall costs and reduced exposure to workers. However, the shipping package materials of construction must maintain integrity as specified by the safety basis of the storage facility throughout the storage period, which is typically well beyond the certified transportation window. In many ways, the certification processes required for interim storage of nuclear materials in shipping packages is similar to life extension programs required for dry cask storage systems for commercial nuclear fuels. The storage of spent nuclear fuel in dry cask storage systems is federally-regulated, and over 1500 individual dry casks have been in successful service up to 20 years in the US. The uncertainty in final disposition will likely require extended storage of this fuel well beyond initial license periods and perhaps multiple re-licenses may be needed. Thus, both the shipping packages and the dry cask storage systems require materials integrity assessments and assurance of continued satisfactory materials performance over times not considered in the original evaluation processes. Test programs for the shipping packages have been established to obtain aging data on materials of construction to demonstrate continued system integrity. The collective data may be coupled with similar data for the dry cask storage systems and used to support extending the service life of shipping packages in both transportation and storage.

A novel facility for ageing materials with narrow-band ultraviolet radiation exposure

International Nuclear Information System (INIS)

Kaerhae, Petri; Ruokolainen, Kimmo; Heikkilae, Anu; Kaunismaa, Merja

2011-01-01

A facility for exploring wavelength dependencies in ultraviolet (UV) radiation induced degradation in materials has been designed and constructed. The device is essentially a spectrograph separating light from a lamp to spectrally resolved UV radiation. It is based on a 1 kW xenon lamp and a flat-field concave holographic grating 10 cm in diameter. Radiation at the wavelength range 250-500 nm is dispersed onto the sample plane of 1.5 cm in height and 21 cm in width. The optical performance of the device has been characterized by radiometric measurements. Using the facility, test samples prepared of regular newspaper have been irradiated from 1 to 8 h. Color changes on the different locations of the aged samples have been quantified by color measurements. Yellowness indices computed from the color measurements demonstrate the capability of the facility in revealing wavelength dependencies of the material property changes in reasonable time frames.

Effects of Thermal Aging on Material Properties, Stress Corrosion Cracking, and Fracture Toughness of AISI 316L Weld Metal

Science.gov (United States)

Lucas, Timothy; Forsström, Antti; Saukkonen, Tapio; Ballinger, Ronald; Hänninen, Hannu

2016-08-01

Thermal aging and consequent embrittlement of materials are ongoing issues in cast stainless steels, as well as duplex, and high-Cr ferritic stainless steels. Spinodal decomposition is largely responsible for the well-known "748 K (475 °C) embrittlement" that results in drastic reductions in ductility and toughness in these materials. This process is also operative in welds of either cast or wrought stainless steels where δ-ferrite is present. While the embrittlement can occur after several hundred hours of aging at 748 K (475 °C), the process is also operative at lower temperatures, at the 561 K (288 °C) operating temperature of a boiling water reactor (BWR), for example, where ductility reductions have been observed after several tens of thousands of hours of exposure. An experimental program was carried out in order to understand how spinodal decomposition may affect changes in material properties in Type 316L BWR piping weld metals. The study included material characterization, nanoindentation hardness, double-loop electrochemical potentiokinetic reactivation (DL-EPR), Charpy-V, tensile, SCC crack growth, and in situ fracture toughness testing as a function of δ-ferrite content, aging time, and temperature. SCC crack growth rates of Type 316L stainless steel weld metal under simulated BWR conditions showed an approximate 2 times increase in crack growth rate over that of the unaged as-welded material. In situ fracture toughness measurements indicate that environmental exposure can result in a reduction of toughness by up to 40 pct over the corresponding at-temperature air-tested values. Material characterization results suggest that spinodal decomposition is responsible for the degradation of material properties measured in air, and that degradation of the in situ properties may be a result of hydrogen absorbed during exposure to the high-temperature water environment.

The effect of extended aging on the optical properties of different zirconia materials.

Science.gov (United States)

Alghazzawi, Tariq F

2017-07-01

The purpose of this study was to determine if the optical properties of zirconia and glass-ceramic (e.max) were affected by low-temperature degradation (aging). Experiment samples were fabricated with seven zirconia brands (n=10): Zenostar, Zirlux, Katana, Bruxzir, DD-BioZX 2 , DD-cubeX 2 , NexxZr; and e.max were used as a control. This resulted in a total of 80 samples in the experiment. The L*, a* and b* were measured for each sample, and then the optical properties including translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) were calculated. The samples were aged (20, 40, 60, 80, 100h), and the optical properties were calculated after each interval. Most zirconia brands had lower L*, higher a*, higher b* with increased aging, which visually corresponds to darker, redder, and more yellow. Aging also increased CR, lowered TP, and lowered OP. e.max was also affected by aging but still had the highest TP (23.9±2.8), L* (81.7±3.4), and lowest CR (0.41±0.05) compared to any zirconia. The Zenostar had the closest TP (24.1±0.4), and L* (90.2±0.5) values to e.max before aging. However, after 100h of aging, the DD-cubeX 2 was least effected and had the highest TP (22.2±0.6) and lowest CR (0.43±0.01) compared with other zirconia samples and highest OP (11.3±0.2) of all ceramic samples. The optical properties of zirconia and e.max materials were affected by aging with the effects increasing with time. The magnitude of change was affected by seven brands of dental zirconia. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

The effect of patient age on bone formation using a fully synthetic nanocrystalline bone augmentation material in maxillary sinus grafting.

Science.gov (United States)

Wolf, Michael; Wurm, Alexander; Heinemann, Friedhelm; Gerber, Thomas; Reichert, Christoph; Jäger, Andreas; Götz, Werner

2014-01-01

Maxillary sinus floor augmentation is a treatment that has been proposed for patients in whom the alveolar bone height is insufficient. This procedure is commonly used in patients aged 40 to 70 years and older. However, little information exists whether the factor of age might influence the outcome of augmentation procedures. The aim of this study was to investigate whether the patient's age has an effect on bone formation and incorporation in maxillary sinus floor augmentation procedures. A fully synthetic nanocrystalline bone augmentation material (NanoBone, Artoss) was used for sinus floor augmentation in patients with a subantral vertical bone height of at least 3 mm and maximum of 7 mm. After 7 months healing time, biopsy specimens were taken and were divided into two groups according to the patient's age. Exclusion criteria were poor general health (eg, severe renal/and or liver disease), history of a radiotherapy in the head region, chemotherapy at the time of surgical procedure, noncompensated diabetes mellitus, symptoms of a maxillary sinus disease, active periodontal or systemic diseases, smoking, and poor oral hygiene. Histologic analyses with hematoxylin-eosin stain were performed. Multinucleated osteoclast-like cells were identified by histochemical staining (tartrate-resistant acid phosphatase [TRAP]). Quantitative and age-dependent assessment of bone formation, residual bone grafting material, and soft tissue formation following sinus augmentation was performed using histomorphometric analysis and the Bonferroni adjustment of the Student t test. Twenty biopsy specimens from 17 patients were taken and divided into two groups according to age (group 1: 41 to 52 years; group 2: 66 to 71 years) containing 10 specimens each, which were analyzed in triplicate resulting in a total of 30 specimens per group. A regeneration process with varying amounts of newly formed bone surrounded by marrow-like tissue was present in all augmented regions. No signs of

Impact of aging and material structure on CANDU plant performance

International Nuclear Information System (INIS)

Nadeau, E.; Ballyk, J.; Ghalavand, N.

2011-01-01

In-service behaviour of pressure tubes is a key factor in the assessment of safety margins during plant operation. Pressure tube deformation (diametral expansion) affects fuel bundle dry out characteristics resulting in reduced margin to trip for some events. Pressure tube aging mechanisms also erode design margins on fuel channels or interfacing reactor components. The degradation mechanisms of interest are primarily deformation, loss of fracture resistance and hydrogen ingress. CANDU (CANada Deuterium Uranium, a registered trademark of the Atomic Energy of Canada Limited used under exclusive licence by Candu Energy Inc.) owners and operators need to maximize plant capacity factor and meet or exceed the reactor design life targets while maintaining safety margins. The degradation of pressure tube material and geometry are characterized through a program of inspection, material surveillance and assessment and need to be managed to optimize plant performance. Candu is improving pressure tubes installed in new build and life extension projects. Improvements include changes designed to reduce or mitigate the impact of pressure tube elongation and diametral expansion rates, improvement of pressure tube fracture properties, and reduction of the implications of hydrogen ingress. In addition, Candu provides an extensive array of engineering services designed to assess the condition of pressure tubes and address the impact of pressure tube degradation on safety margins and plant performance. These services include periodic and in-service inspection and material surveillance of pressure tubes and deterministic and probabilistic assessment of pressure tube fitness for service to applicable standards. Activities designed to mitigate the impact of pressure tube deformation on safety margins include steam generator cleaning, which improves trip margins, and trip design assessment to optimize reactor trip set points restoring safety and operating margins. This paper provides an

ACTIVE AGEING AND MATERIAL DEPRIVATION OF OLDER GENERATIONS IN EUROPE AND IN POLAND: HOW DO THEY INTERPLAY?

Directory of Open Access Journals (Sweden)

Jolanta Perek-Białas

2015-07-01

Full Text Available The active ageing concept includes domain of independent, healthy and secure living which includes financial aspects, measured by risk of poverty and material deprivation. The key questions of this paper are: how are the poverty indicators related to each other in the active ageing index?; in what ways are they related to some of the other indicators included in the index (such as employment? And which countries in Europe are “winners” and which are “losers” in this particular financial aspects based on the Active Ageing Index? Besides of this, the example of sub-national application of active ageing index for Poland was presented with showing relation of these financial indicators in the analysis.

Study of Polymer Material Aging by Laser Mass Spectrometry, UV-Visible Spectroscopy, and Environmental Scanning Electron Microscopy

OpenAIRE

Junien Exposito; Claude Becker; David Ruch; Frédéric Aubriet

2007-01-01

Dyed natural rubber (NR) and styrene butadiene rubber (SBR), designed for outdoor applications, were exposed to an accelerated artificial aging in xenon light. The aging results in the deterioration of the exposed surface material properties. The ability of dyed polymers to withstand prolonged sunlight exposure without fading or undergoing any physical deterioration is largely determined not only by the photochemical characteristics of the absorbing dyestuff itself but also by the polymer str...

Metallic materials for the hydrogen energy industry and main gas pipelines: complex physical problems of aging, embrittlement, and failure

International Nuclear Information System (INIS)

Nechaev, Yu S

2008-01-01

The possibilities of effective solutions of relevant technological problems are considered based on the analysis of fundamental physical aspects, elucidation of the micromechanisms and interrelations of aging and hydrogen embrittlement of materials in the hydrogen industry and gas-main industries. The adverse effects these mechanisms and processes have on the service properties and technological lifetime of materials are analyzed. The concomitant fundamental process of formation of carbohydride-like and other nanosegregation structures at dislocations (with the segregation capacity 1 to 1.5 orders of magnitude greater than in the widely used Cottrell 'atmosphere' model) and grain boundaries is discussed, as is the way in which these structures affect technological processes (aging, hydrogen embrittlement, stress corrosion damage, and failure) and the physicomechanical properties of the metallic materials (including the technological lifetimes of pipeline steels). (reviews of topical problems)

Assessment of Cable Aging Equipment, Status of Acquired Materials, and Experimental Matrix at the Pacific Northwest National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Fifield, Leonard S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westman, Matthew P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zwoster, Andy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schwenzer, Birgit [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-03-30

The need for increased understanding of the aging and degradation behavior for polymer components of nuclear power plant electrical cables is described in this report. The highest priority materials for study and the resources available at PNNL for these studies are also described. The anticipated outcomes of the PNNL work described are : improved understanding of appropriate accelerated aging conditions, improved knowledge of correlation between observable aging indicators and cable condition in support of advanced non-destructive evaluation methods, and practical knowledge of condition-based cable lifetime prediction.

Las Lunas (Yuncler, Toledo. A Bronze Age hoard with metallic materials from the southern Iberian Meseta

Directory of Open Access Journals (Sweden)

Urbina Martínez, Dionisio

2010-06-01

Full Text Available Here we present the results of the preliminary study carried out on a new group of metallic materials of the Final Bronze Age, recovered at the end of 2008 in the archaeological excavations at the settlement of Las Lunas (Yuncler, Toledo, Spain. Its geographical situation far away from the main zones of distribution of this type of finds, the singularity of the materials, and the evidence of Atlantic and Mediterranean relations make these materials a remarkable sample for the study of the Final Bronze Age in the centre of the Iberian Peninsula.

Se exponen los resultados del primer estudio realizado sobre un nuevo conjunto de materiales metálicos del Bronce Final recuperado a finales de 2008 en las excavaciones arqueológicas del yacimiento de Las Lunas (Yuncler, Toledo, España. La localización geográfica del hallazgo, lejos de las principales zonas de dispersión conocidas para este tipo de conjuntos, la singularidad de los objetos que integra, y las relaciones atlánticas y mediterráneas que evidencian sus materiales, lo convierten en un ejemplo destacado para el estudio de este período en el centro de la Península Ibérica.

Explaining the impact of poverty on old-age frailty in Europe: material, psychosocial and behavioural factors.

Science.gov (United States)

Stolz, Erwin; Mayerl, Hannes; Waxenegger, Anja; Freidl, Wolfgang

2017-12-01

Previous research found poverty to be associated with adverse health outcomes among older adults but the factors that translate low economic resources into poor physical health are not well understood. The goal of this analysis was to assess the impact of material, psychosocial, and behavioural factors as well as education in explaining the poverty-health link. In total, 28 360 observations from 11 390 community-dwelling respondents (65+) in the Survey of Health, Ageing and Retirement in Europe (2004-13, 10 countries) were analysed. Multilevel growth curve models were used to assess the impact of combined income and asset poverty risk on old-age frailty (frailty index) and associated pathway variables. In total, 61.8% of the variation of poverty risk on frailty level was explained by direct and indirect effects. Results stress the role of material and particularly psychosocial factors such as perceived control and social isolation, whereas the role of health behaviour was negligible. We suggest to strengthen social policy and public health efforts in order to fight poverty and its deleterious health effects from early age on as well as to broaden the scope of interventions with regard to psychosocial factors. © The Author 2017. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Geopolymer resin materials, geopolymer materials, and materials produced thereby

Energy Technology Data Exchange (ETDEWEB)

Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

2018-01-09

A product formed from a first material including a geopolymer resin material, a geopolymer material, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

PWSCC issues and material aging management for nuclear power plants in Korea

Energy Technology Data Exchange (ETDEWEB)

Hwang, Seong Sik; Lim, Yun Soo; Kim, Dong Jin; Kim, Sung Woo; Kim, Hong Pyo [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-10-15

The primary water stress corrosion cracking (PWSCC) of alloy 600 in a PWR has been reported in the control rod drive mechanism (CRDM). Beginning in the mid-seventies, the pressurized water reactor (PWR) plants suffered from a sequence of SCC events mostly confined to S/G tubes, initially ODSCC, and then PWSCC. PWSCC was first reported in Bugey 3 vessel head penetration made of forged alloy 600 materials in September 1991. Other PWRs experienced cracking attributed to the PWSCC of the major primary side weld area made from alloy 182 at the end of the year 2000. Examples of dissimilar metal butt welds between the main austenitic stainless steel primary circuit piping and the outlet pressure vessel nozzles are the cracking of Ringhals 4, V. C. Summer and some J-groove welds of the CRDM of the RVH at Oconee 1. In addition to the Reactor Vessel Head (RVH), the PWSCC of alloy 182/82 has been reported at bottom mounted instrumentation (BMI) nozzle J-welds, steam generator(SG) J-weld drain nozzle, and SG tube sheet cladding. Two cases of boric acid precipitation were reported at the bottom head surface of a SG in Korea. Cracking was found in the cold leg drain nozzles made of alloy 600 in two units, hot side nozzles were fabricated with alloy 690 from the beginning. The cracking of steam generator tubings made of alloy 600 is another concern in Korea, because some plants still have alloy 600 HTMA tubings. The flow accelerated corrosion of secondary pipings is another type of corrosion problems, though it has not been treated as a severe problem in Korea. To properly manage the corrosion issues and seek out research items for maintaining the integrity of nuclear plants, the PRIMA-Net (Proactive Research and Innovative Material Aging Network) was organized in 2007. The research and development expert group consists of a National research laboratory (KAERI), regulatory body (KINS), utility (KHNP), engineering and design company (KEPCO EC), manufacturer (Doosan Heavy

Geopolymer resin materials, geopolymer materials, and materials produced thereby

Science.gov (United States)

Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

2016-03-29

A product formed from a first material including a geopolymer resin material, a geopolymer resin, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

Isotopic fractionation of NBS oxalic acid and its influence in the calculated age of materials

International Nuclear Information System (INIS)

Nehmi, V.A.

1979-10-01

The intensity of the isotopic fractionation during the oxidation of NBS oxalic acid to carbon dioxide was checked. 30 reactions of oxidation of NBS oxalic acid with potassium permanganate were made. The resultant isotopic composition of CO 2 has been determined with a mass-spectrometer. A conclusion has been reached that the average of Δ 13 C is - 18.9% o with variation between - 17.7 and - 21.2%o. For values of Δ 13 C equal to - 22.0%o, the calculated age with isotopic correction shows the following deviations in relation to non-corrected age: 4% for materials of 1,000 years and 0.3% for 20,000 years.(Author) [pt

Nuclear power plant cable materials :

Energy Technology Data Exchange (ETDEWEB)

Celina, Mathias C.; Gillen, Kenneth T; Lindgren, Eric Richard

2013-05-01

A selective literature review was conducted to assess whether currently available accelerated aging and original qualification data could be used to establish operational margins for the continued use of cable insulation and jacketing materials in nuclear power plant environments. The materials are subject to chemical and physical degradation under extended radiationthermal- oxidative conditions. Of particular interest were the circumstances under which existing aging data could be used to predict whether aged materials should pass loss of coolant accident (LOCA) performance requirements. Original LOCA qualification testing usually involved accelerated aging simulations of the 40-year expected ambient aging conditions followed by a LOCA simulation. The accelerated aging simulations were conducted under rapid accelerated aging conditions that did not account for many of the known limitations in accelerated polymer aging and therefore did not correctly simulate actual aging conditions. These highly accelerated aging conditions resulted in insulation materials with mostly inert aging processes as well as jacket materials where oxidative damage dropped quickly away from the air-exposed outside jacket surface. Therefore, for most LOCA performance predictions, testing appears to have relied upon heterogeneous aging behavior with oxidation often limited to the exterior of the cable cross-section a situation which is not comparable with the nearly homogenous oxidative aging that will occur over decades under low dose rate and low temperature plant conditions. The historical aging conditions are therefore insufficient to determine with reasonable confidence the remaining operational margins for these materials. This does not necessarily imply that the existing 40-year-old materials would fail if LOCA conditions occurred, but rather that unambiguous statements about the current aging state and anticipated LOCA performance cannot be provided based on

Impact of aging and material structure on CANDU plant performance

Energy Technology Data Exchange (ETDEWEB)

Nadeau, E.; Ballyk, J.; Ghalavand, N. [Candu Energy Inc., Mississauga, Ontario (Canada)

2011-07-01

In-service behaviour of pressure tubes is a key factor in the assessment of safety margins during plant operation. Pressure tube deformation (diametral expansion) affects fuel bundle dry out characteristics resulting in reduced margin to trip for some events. Pressure tube aging mechanisms also erode design margins on fuel channels or interfacing reactor components. The degradation mechanisms of interest are primarily deformation, loss of fracture resistance and hydrogen ingress. CANDU (CANada Deuterium Uranium, a registered trademark of the Atomic Energy of Canada Limited used under exclusive licence by Candu Energy Inc.) owners and operators need to maximize plant capacity factor and meet or exceed the reactor design life targets while maintaining safety margins. The degradation of pressure tube material and geometry are characterized through a program of inspection, material surveillance and assessment and need to be managed to optimize plant performance. Candu is improving pressure tubes installed in new build and life extension projects. Improvements include changes designed to reduce or mitigate the impact of pressure tube elongation and diametral expansion rates, improvement of pressure tube fracture properties, and reduction of the implications of hydrogen ingress. In addition, Candu provides an extensive array of engineering services designed to assess the condition of pressure tubes and address the impact of pressure tube degradation on safety margins and plant performance. These services include periodic and in-service inspection and material surveillance of pressure tubes and deterministic and probabilistic assessment of pressure tube fitness for service to applicable standards. Activities designed to mitigate the impact of pressure tube deformation on safety margins include steam generator cleaning, which improves trip margins, and trip design assessment to optimize reactor trip set points restoring safety and operating margins. This paper provides an

Soil microbial biomass under pine forests in the north-western Spain: influence of stand age, site index and parent material

Energy Technology Data Exchange (ETDEWEB)

Mahia, J.; Perez-Ventura, L.; Cabaneiro, A.; Diaz-Ravina, M.

2006-07-01

The effects of stand age, site index and parent material on soil biochemical properties related to biomass (extractable C, microbial C and metabolic quotient) were examined in the 0-15 cm mineral soil layers of Pinus pinaster and Pinus sylvestris stand from NW Spain. Two productivity levels (low and high site index), two ages (young and old) and two parent soil materials (granite and acid schists) were considered. The data indicated that there were differences in microbial parameters in soils under different species. In general in P. pinaster forest higher values of biochemical parameters expressed on organic C basis, were observed in the stands of high site index as compared with the low ones; in contrast, in P. sylvestris no differences among stand site index were detected. In both species different results were also observed depending on parent material and a significant effect of stand age was detected for extractable C and microbial C in P. pinaster forest developed over granite. The data seem to indicate that measured parameters may have the potential to be used as indicators of the effect of forest management on soil organic matter quality. (Author) 25 refs.

Effects of irradiation and thermal aging upon fatigue-crack growth behavior of reactor pressure boundary materials. [Neutrons

Energy Technology Data Exchange (ETDEWEB)

James, L. A.

1978-10-01

Two processes that have the potential to produce degradation in the properties of pressure boundary materials are neutron irradiation and long-time thermal aging. This paper uses linear-elastic fracture mechanics techniques to assess the effect of these two processes upon the fatigue-crack growth behavior of a number of alloys commonly employed in reactor pressure boundaries. The materials evaluated include ferritic steels, austenitic stainless steels, and nickel-base alloys typical of those employed in a number of reactor types including water-cooled, gas-cooled, and liquid-metal-cooled designs.

Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Nie,J.; Braverman, J.; Hofmayer, C.; Kim, M. K.; Choi, I-K.

2009-04-27

When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of aging of structures and components in NPPs. Three specific areas that are included in the KAERI research project, related to seismic probabilistic risk assessment (PRA), are probabilistic seismic hazard analysis, seismic fragility analysis including the effects of aging, and a plant seismic risk analysis. To support the development of seismic capability evaluation technology for degraded structures and components, KAERI entered into a collaboration agreement with Brookhaven National Laboratory (BNL) in 2007. The collaborative research effort is intended to continue over a five year period with the goal of developing seismic fragility analysis methods that consider the potential effects of age-related degradation of SSCs, and using these results as input to seismic PRAs. In the Year 1 scope of work BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. This information is presented in the Annual Report for the Year 1 Task, identified as BNL Report-81741-2008 and also designated as KAERI/RR-2931/2008. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, the report provides a description of U.S. current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. This report

The effect of the accelerated aging on the mechanical properties of the PMMA denture base materials modified with itaconates

Directory of Open Access Journals (Sweden)

Spasojević Pavle M.

2011-01-01

Full Text Available This study evaluated the effect of accelerated ageing on the tensile strength, elongation at break, hardness and Charpy impact strength in commercial PMMA denture base material modified with di-methyl itaconate (DMI and di-n-butyl itaconate (DBI. The samples were prepared by modifying commercial formulation by addition of itaconates in the amounts of 2.5, 5, 7.5 and 10% by weight. After polymerization samples were characterized by FT-IR and DSC analysis while residual monomer content was determined by HPLC-UV. Accelerated ageing was performed at 70°C in water for periods of 7, 15 and 30 days. Tensile measurements were performed using Instron testing machine while the hardness of the polymerized samples was measured by Shore D method. The addition of itaconate significantly reduces the residual MMA. Even at the small amounts of added itaconates (2.5% the residual MMA content was reduced by 50%. The increase of itaconate content in the system leads to the decrease of residual MMA. It has been found that the addition of di-n-alkyl itaconates decreases the tensile strength, hardness and Charpy impact strength and increases elongation at break. Samples modified with DMI had higher values of tensile strength, hardness and Charpy impact strength compared to the ones modified with DBI. This is explained by the fact that DBI has longer side chain compared to DMI. After accelerated ageing during a 30 days period the tensile strength decreased for all the investigated samples. The addition of DMI had no effect on the material ageing and the values for the tensile strength of all of the investigated samples decreased around 20%, while for the samples modified with DBI, the increase of the amount of DBI in the polymerized material leads to the higher decrease of the tensile strength after the complete accelerated ageing period od 30 days, aulthough after the first seven days of the accelerated ageing the values of hardness have increased for all of the

Constitutive modelling of creep-ageing behaviour of peak-aged aluminium alloy 7050

Directory of Open Access Journals (Sweden)

Yang Yo-Lun

2015-01-01

Full Text Available The creep-ageing behaviour of a peak-aged aluminium alloy 7050 was investigated under different stress levels at 174 ∘C for up to 8 h. Interrupted creep tests and tensile tests were performed to investigate the influences of creep-ageing time and applied stress on yield strength. The mechanical testing results indicate that the material exhibits an over-ageing behaviour which increases with the applied stress level during creep-ageing. As creep-ageing time approaches 8 h, the material's yield strength under different stress levels gradually converge, which suggests that the difference in mechanical properties under different stress conditions can be minimised. This feature can be advantageous in creep-age forming to the formed components such that uniformed mechanical properties across part area can be achieved. A set of constitutive equations was calibrated using the mechanical test results and the alloy-specific material constants were obtained. A good agreement is observed between the experimental and calibrated results.

Application of positron age-momentum correlation measurements to the study of defects in inorganic materials

International Nuclear Information System (INIS)

Tanigawa, S.; Kishimoto, Y.; Tsuda, N.

1982-01-01

The two parameter correlation measurements between the positron age and the momentum of annihilating pairs were applied to the study of defects in plastically deformed MgO and Al 2 O 3 single crystals, nonstoichiometric sintered BaTiO 3 samples and irradiated NaCl single crystals. The results in MgO, Al 2 O 3 and BaTiO 3 showed the bell shape dependence of lifetimes on momentum indicating that the behavior of positrons in these materials can be well described by the simple trapping model with the condition that all positrons are initially in a free Bloch state. On the other hand, the X-ray irradiation of NaCl crystals produced a complicated dependence of lifetime momentum indicating the presence of positronium in this material. (Auth.)

Thermal aging of electrolytes used in lithium-ion batteries - An investigation of the impact of protic impurities and different housing materials

Science.gov (United States)

Handel, Patricia; Fauler, Gisela; Kapper, Katja; Schmuck, Martin; Stangl, Christoph; Fischer, Roland; Uhlig, Frank; Koller, Stefan

2014-12-01

Thermal degradation products in lithium-ion batteries result mainly from hydrolysis sensitivity of lithium hexafluorophosphate (LiPF6). As organic carbonate solvents contain traces of protic impurities, the thermal decomposition of electrolytes is enhanced. Therefore, resulting degradation products are studied with nuclear magnetic resonance spectroscopy (NMR) and gas chromatography mass spectrometry (GC-MS). The electrolyte contains 1 M LiPF6 in a binary mixture of ethylene carbonate (EC) and diethylene carbonate (DEC) in a ratio of 1:2 (v/v) and is aged at ambient and elevated temperature. The impact of protic impurities, either added as deionized water or incorporated in positive electrode material, upon aging is investigated. Further, the influence of different housing materials on the electrolyte degradation is shown. Difluorophosphoric acid is identified as main decomposition product by NMR-spectroscopy. Traces of other decomposition products are determined by headspace GC-MS. Acid-base and coulometric titration are used to determine the total amount of acid and water content upon aging, respectively. The aim of this investigation is to achieve profound understanding about the thermal decomposition of one most common used electrolyte in a battery-like housing material.

Taking into account of the aging and the damage in the size determination of composite materials structures

International Nuclear Information System (INIS)

Mercier, J.

2006-11-01

The aim of this study was to better understand the aging of glass fibres-epoxy composites exposed to humid conditions and loading so as to predict its effects on the lifetimes of composite structures. Water diffusion was first experimentally investigated by gravimetric method to determine water sorption kinetics for different humid conditions. A Fickian model of diffusion could describe the results obtained. Specimens, saturated at different levels, were mechanically characterised. Decreases of mechanical properties as a function of water uptake were revealed by tensile tests. Damage by cracking and the coupling with humidity were then studied. Differences between reversible and irreversible changes in properties were revealed and analysed in detail. A predictive model taking into account effects due to water and/or mechanical loading is proposed, using finite element method. As a first step, in modelling the diffusion process, the non-uniform water distribution across the composite are determined for any conditions (temperature, humidity, aging time). The resulting mechanical properties of the material, as a function of the absorbed water concentration, are determined in each point. Then, diffusion/mechanic coupled calculation allows to determine material global properties from properties at each point. It is then possible to predict continuous evolution of rigidity during aging time, at all stages of water absorption and matrix cracking, for any condition (temperature, humidity, thickness, mechanical loading level). (author)

Effect of varying core thicknesses and artificial aging on the color difference of different all-ceramic materials.

Science.gov (United States)

Dikicier, Sibel; Ayyildiz, Simel; Ozen, Julide; Sipahi, Cumhur

2014-11-01

Clinicians should reserve all-ceramics with high translucency for clinical applications in which high-level esthetics are required. Furthermore, it is unclear whether a correlation exists between core thickness and color change. The aim of this study was to examine the effects of different core thicknesses and artificial aging on the color stability of three all-ceramic systems. Ninety disc-shaped cores with different thicknesses (0.5 mm, 0.8 mm and 1.0 mm) were prepared from three all-ceramic systems, In-Ceram Alumina (IC), IPS e.max Press (EM) and Katana (K). The colors of the samples were measured with a spectrophotometer and the color parameters (L*, a*, b*, ΔE) were calculated according to the CIE L*a*b* (Commission Internationale de L'Eclairage) color system before and after aging. The effects of aging on color parameters were statistically significant (p artificial aging affected color stability of the all-ceramic materials tested.

Materials 2014: a great success for materials sector

International Nuclear Information System (INIS)

Isnard, Olivier; Crepin, Jerome

2014-01-01

In this work are presented the summaries of the 19 symposiums presented at the conference: 'Materials 2014' and whose topics were: eco-materials, materials for energy storage and conversion, strategic materials, rare elements and recycling, surfaces functionalization and physico-chemical characterization, interfaces and coatings, corrosion, aging, durability, damage mechanical behaviours, disordered materials, glasses and their functionalization, materials and health, functional materials, porous, granular and with a high surface area materials, nano-materials, nano-structured systems, assembling processes, carbonaceous materials, great instruments and studies of materials, materials in severe conditions, powder forming processes, metallic materials and structures lightening. (O.M.)

Dynamic J-R Characteristics of RCS Pipe Materials for Ulchin Unit 3/4. (Evaluation of Dynamic Strain Aging Effects)

Energy Technology Data Exchange (ETDEWEB)

Hong, Jun Hwa; Lee, Bong Sang; Yoon, Ji Hyun; Oh, Jong Myung; Kim, Jin Won [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-09-01

5 materials (45 1T-CT specimens) were tested to evaluate dynamic J-R characteristics of RCS Pipe Materials for Ulchin Unit 3/4 (Evaluation of Dynamic Strain Aging Effects). The tests were performed by DCPD method at 316 deg C and 25 deg C. The loading rates were 1000mm/min and 2000mm/min. The objectives of this project were to obtain the dynamic J-R curves data of ferritic steels for application of LBB to the RCS pipes of Ulchin Unit 3/4. The test results showed that all of the tested dynamic J-R curves of 5 materials were above the lower bound curve of static J-R curve of pipe materials for Ulchin Unit 3/4. 10 refs., 4 tabs., 16 figs. (author)

Education, material condition and physical functioning trajectories in middle-aged and older adults in Central and Eastern Europe: a cross-country comparison

Science.gov (United States)

Hu, Yaoyue; Pikhart, Hynek; Pająk, Andrzej; Kubínová, Růžena; Malyutina, Sofia; Besala, Agnieszka; Peasey, Anne; Marmot, Michael; Bobak, Martin

2016-01-01

Background Two competing hypotheses, cumulative advantage/disadvantage and age-as-leveller, have been proposed to explain the contradictory findings on socioeconomic differences in health over the lifespan. To test these hypotheses, this investigation examined the influence of educational attainment and material condition on individual trajectories of physical functioning (PF) in unexplored ageing populations in Central and Eastern Europe. Methods 28 783 men and women aged 45–69 years selected from populations in seven Czech towns, Krakow (Poland) and Novosibirsk (Russia). PF was measured by the Physical Functioning Subscale (PF-10) of the Short-Form-36 questionnaire (SF-36) at baseline and three subsequent occasions. The highest educational attainment was self-reported at baseline, and material condition was captured by the sum score of 12 household amenities and assets. Results In all cohorts, participants with a university degree had the highest PF-10 score at baseline and slowest rate of decline in the score during follow-up, while the lowest baseline scores and fastest decline rate were found in participants with less than secondary education in all cohorts and in Russians with secondary education. Similar disparities in the baseline PF-10 score and decline rate were observed across tertiles of material condition, but differences in decline rates across the three tertiles among Czechs or between the lower two tertiles among Russians were not statistically significant. Conclusions Disparities in PF by educational attainment and material condition among middle-aged and older adults in Central and Eastern Europe existed at baseline and widened during ∼10 years of follow-up, supporting the cumulative advantage/disadvantage hypothesis. PMID:27194710

New age constraints on the Middle Stone Age occupations of Kharga Oasis, Western Desert, Egypt.

Science.gov (United States)

Smith, Jennifer R; Hawkins, Alicia L; Asmerom, Yemane; Polyak, Victor; Giegengack, Robert

2007-06-01

Spring-deposited carbonate rocks, or tufas, exposed along the flanks of the Libyan Plateau near Kharga Oasis, Western Desert, Egypt, can provide a directly datable stratigraphic context for Middle Stone Age/Middle Paleolithic (MSA/MP) archaeological material, if such material can be found in situ within tufa strata. Two such localities (Mata'na Site G and Bulaq Wadi 3 Locus 1) described by Caton-Thompson were revisited and sampled for uranium-series analysis. At Mata'na Site G (KH/MT-02), Middle Stone Age ("Upper Levalloisian") material is underlain by tufa with a uranium-series age of 127.9+/-1.3 ka, and overlain by tufa with an age of 103+/-14 ka. At Bulaq Wadi 3 Locus 1, a uranium-series age of 114.4+/-4.2 ka on tufa capping a small collection of Middle Stone Age artifacts also provides a minimum age constraint on that material. Tufa underlying an MSA workshop (KH/MD-10) indicates that this assemblage, characterized by use of several Levallois reduction methods, was deposited after approximately 124 ka. Furthermore, uranium-series ages averaging approximately 133 ka on a Wadi Midauwara tufa (WME-10) without associated archaeological material suggest that one period of spring flow in the region began during the Marine Isotope Stage 6/5e transition, prior to the warmest portion of the last interglacial period. The dated archaeological material suggests that the distinction that has been identified between Nubian and non-Nubian complexes in the Nile Valley may hold for the Western Desert, although local complexity has yet to be fully described.

Ageing at 1203K of 20/25Nb stainless steel AGR fuel cladding material - microstructural development and its effect on creep properties

International Nuclear Information System (INIS)

Ecob, R.C.; Gilmour, T.C.

1986-11-01

The effects of ageing at 1203K for times up to 2.69Ms on the uniaxial constant stress creep properties of a 20/25Nb AGR fuel cladding alloy at 1073 and 1173K have been investigated and correlated with quantitative measurements of the microstructural developments which occur during exposure to both the ageing and creep testing temperatures. A single creep testing stress of 86.6MPa has been used. It is shown that the variation of minimum creep rate can only be explained in terms of the observed NbC particle coarsening at short ageing times (up to 7.44ks). After longer ageing treatments the minimum creep rate tends to decrease with ageing time, which is interpreted as being due to grain growth and, in particular, the onset of secondary recrystallisation. The minimum creep rates displayed by the material are reduced by factors of up to 20 in the presence of partial secondary recrystallisation. It is concluded that the effects of the development of the NbC particle distributions during 1203K ageing on the 1073 or 1173K uniaxial creep endurance of the material are relatively small. Consideration is given to the circumstances in which it might be of more importance, which include longer 1203K ageing treatments, more complex low strain stress/strain cycles. During the ageing treatments and creep tests investigated in the present work, the only significant influences on creep properties arise from grain growth and secondary recrystallisation. (UK)

Thermal-aging evaluation of on site aged cast duplex stainless steel

International Nuclear Information System (INIS)

Yamada, Takuyo; Fujii, Katsuhiko; Aoki, Masanori; Arioka, Koji

2013-01-01

In this study, thermal-aging evaluation has been performed using service aged elbow pipe in PWR plant, aged at 320degC for 196,500h. As a result, micro Vickers hardness of ferrite in service material (SCS14A), HV(0.025) was 616∼630. Since micro Vickers hardness of un-aged ferrite phase is about HV(0.025)=300 in commercial SCS14A, the increasing of ferrite hardness during aging was 300. Cr-rich and Fe-rich regions were observed in the ferrite phase using Atom-probe analysis. In addition, Ni, Si and Mo clustering were also observed in the ferrite phase. So the ferrite phase was hardened caused by these micro-structural changes. Micro Vickers hardness of austenite phase, HV(0.025) was 155∼180. Since micro Vickers hardness of un-aged austenite phase is about HV(0.025)=180∼200, and no micro-structural change was observed in the austenite phase, so on change was observed in the austenite phase during aging. To compare the micro Vickers hardness of ferrite in service and accelerated materials using activation energy, Q=100 kJ/mol, the ferrite hardness of in service material was very low rather than predictive line. This seems the activation energy was too conservative. (author)

On aging factors, aging mechanisms and their combinations in the primary circuit of NPPs

International Nuclear Information System (INIS)

Varga, T.; Brumovsky, M.

1993-01-01

Ageing is the dominating problem of elder nuclear power plant (NPP) components but still can not be neglected even for the newest ones. Ageing may express itself in different ways: irradiated steel parts may become embrittled, chromium alloy steels may decompose, fatigue life may become exhausted so that cracks may be formed and finally, corrosion attack may result in stress corrosion cracking. However, even synthetics and rubber parts may become inelastic, swell, shrink or crack, electric contacts may be oxydised, or isolations may lose their high electric resistance. Therefore, experts in the different components and their materials have collected and published not only plenty of observations, but also a number of more or less systematic approaches. A general picture, however, still seems to be lacking, due to the fact that ageing factors and mechanisms are not defined and used properly, i.e. - ageing factors act because of the service conditions of the components, as well as the characteristics of the materials which provoke ageing mechanisms - ageing mechanisms cause the changing of properties of the materials involved - combinations of single ageing mechanisms, which can be double, triple or multiple, change and accelerate the ageing process - the consequence of ageing mechanisms is the altering of the properties of the material depending on the lifetime. In this paper we shall try to show a systematic approach to a potential ageing analysis concerning the main metallic components of primary circuits of NPP's - connection between ageing factors, ageing mechanisms and their consequences/effects on component behaviour

Effectiveness of integrated science instructional material on pressure in daily life theme to improve digital age literacy of students

Science.gov (United States)

Asrizal; Amran, A.; Ananda, A.; Festiyed; Khairani, S.

2018-04-01

Integrated science learning and literacy skills are relevant issues in Indonesian’s education. However, the use of the integrated science learning and the integration of literacy in learning cannot be implemented well. An alternative solution of this problem is to develop integrated science instructional material on pressure in daily life theme by integrating digital age literacy. Purpose of research is to investigate the effectiveness of the use of integrated science instructional material on pressure in daily life theme to improve knowledge competence, attitudes competence and literacy skills of students. This research was a part of development research which has been conducted. In the product testing stage of this research and development was used before and after design of treatment for one sample group. Instruments to collect the data consist of learning outcomes test sheet, attitude observation sheet, and performance assessment sheet of students. Data analysis techniques include descriptive statistics analysis, normality test, homogeneity test, and paired comparison test. Therefore, the important result of research is the use of integrated science instructional material on pressure in daily life theme is effective in scientific approach to improve knowledge competence, attitudes competence, and digital age literacy skills of grade VIII students at 95% confidence level.

Education, material condition and physical functioning trajectories in middle-aged and older adults in Central and Eastern Europe: a cross-country comparison.

Science.gov (United States)

Hu, Yaoyue; Pikhart, Hynek; Pająk, Andrzej; Kubínová, Růžena; Malyutina, Sofia; Besala, Agnieszka; Peasey, Anne; Marmot, Michael; Bobak, Martin

2016-11-01

Two competing hypotheses, cumulative advantage/disadvantage and age-as-leveller, have been proposed to explain the contradictory findings on socioeconomic differences in health over the lifespan. To test these hypotheses, this investigation examined the influence of educational attainment and material condition on individual trajectories of physical functioning (PF) in unexplored ageing populations in Central and Eastern Europe. 28 783 men and women aged 45-69 years selected from populations in seven Czech towns, Krakow (Poland) and Novosibirsk (Russia). PF was measured by the Physical Functioning Subscale (PF-10) of the Short-Form-36 questionnaire (SF-36) at baseline and three subsequent occasions. The highest educational attainment was self-reported at baseline, and material condition was captured by the sum score of 12 household amenities and assets. In all cohorts, participants with a university degree had the highest PF-10 score at baseline and slowest rate of decline in the score during follow-up, while the lowest baseline scores and fastest decline rate were found in participants with less than secondary education in all cohorts and in Russians with secondary education. Similar disparities in the baseline PF-10 score and decline rate were observed across tertiles of material condition, but differences in decline rates across the three tertiles among Czechs or between the lower two tertiles among Russians were not statistically significant. Disparities in PF by educational attainment and material condition among middle-aged and older adults in Central and Eastern Europe existed at baseline and widened during ∼10 years of follow-up, supporting the cumulative advantage/disadvantage hypothesis. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Study of Polymer Material Aging by Laser Mass Spectrometry, UV-Visible Spectroscopy, and Environmental Scanning Electron Microscopy

Directory of Open Access Journals (Sweden)

Junien Exposito

2007-01-01

Full Text Available Dyed natural rubber (NR and styrene butadiene rubber (SBR, designed for outdoor applications, were exposed to an accelerated artificial aging in xenon light. The aging results in the deterioration of the exposed surface material properties. The ability of dyed polymers to withstand prolonged sunlight exposure without fading or undergoing any physical deterioration is largely determined not only by the photochemical characteristics of the absorbing dyestuff itself but also by the polymer structure and fillers. Results obtained by laser mass spectrometry, UV-visible spectroscopy, and environmental scanning electron microscopy indicate that dyed filled NR and SBR samples behave differently during the photo-oxidation. The fading of the dyed polymers was found to be promoted in the NR sample. This can be correlated with LDI-FTICRMS results, which show the absence of [M-H]− orange pigment pseudomolecular ion and also its fragment ions after aging. This is confirmed by both EDX and UV/Vis spectroscopy. EDX analysis indicates a concentration of chlorine atoms, which can be considered as a marker of orange pigment or its degradation products, only at the surface of SBR flooring after aging. Reactivity of radicals formed during flooring aging has been studied and seems to greatly affect the behavior of such organic pigments.

Applications of bioactive material from snakehead fish (Channa striata) for repairing of learning-memory capability and motoric activity: a case study of physiological aging and aging-caused oxidative stress in rats

Science.gov (United States)

Sunarno, Sunarno; Muflichatun Mardiati, Siti; Rahadian, Rully

2018-05-01

Physiological aging and aging due to oxidative stress are a major factor cause accelerated brain aging. Aging is characterized by a decrease of brain function of the hippocampus which is linked to the decline in the capability of learning-memory and motoric activity. The objective of this research is to obtain the important information about the mechanisms of brain antiaging associated with the improvement of hippocampus function, which includes aspects of learning-memory capability and motoric activity as well as mitochondrial ultrastructure profile of hippocampus cornu ammonis cells after treated by fish snakehead fish extract. Snakehead fish in Rawa Pening Semarang District allegedly holds the potential of endemic, which contains bioactive antiaging material that can prevent aging or improve the function of the hippocampus. This research has been conducted using a completely randomized design consisting of four treatments with five replications. The treatments were including rats with physiological aging or aging due to oxidative stress which was treated and without treated with meat extract of snakehead fish. The research was divided into two stages, i.e., determining of learning-memory capability, and determining motoric activity. The measured-parameters are time response to find feed, distance travel, time stereotypes, ambulatory time, and resting time. The result showed that the snakehead fish meat extract might improve function hippocampus, both in physiological aging or aging due to oxidative stress. The capability of learning and memory showed that the rats in both conditions of aging after getting treatment of meat extract of snakehead fish could get a feed in the fourth arm maze faster than rats untreated snakehead fish meat extract. Similarly, the measurement of the distance traveled, time stereotypes, ambulatory time, and resting time showed that rats which received treatment of meat extract of snakehead fish were better than the untreated rats. To

Soiling of building envelope surfaces and its effect on solar reflectance – Part II: Development of an accelerated aging method for roofing materials

Energy Technology Data Exchange (ETDEWEB)

Sleiman, Mohamad [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kirchstetter, Thomas W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Berdahl, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gilbert, Haley E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Quelen, Sarah [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Marlot, Lea [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Preble, Chelsea V. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Chen, Sharon [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Montalbano, Amandine [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rosseler, Olivier [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Akbari, Hashem [Concordia Univ., Montreal (Canada); Levinson, Ronnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Destaillats, Hugo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-01-09

Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric particulate matter and the growth of microorganisms, each of which absorb sunlight. Weathering of materials occurs with exposure to water, sunlight, and high temperatures. This study developed an accelerated aging method that incorporates features of soiling and weathering. The method sprays a calibrated aqueous soiling mixture of dust minerals, black carbon, humic acid, and salts onto preconditioned coupons of roofing materials, then subjects the soiled coupons to cycles of ultraviolet radiation, heat and water in a commercial weatherometer. Three soiling mixtures were optimized to reproduce the site-specific solar spectral reflectance features of roofing products exposed for 3 years in a hot and humid climate (Miami, Florida); a hot and dry climate (Phoenix, Arizona); and a polluted atmosphere in a temperate climate (Cleveland, Ohio). A fourth mixture was designed to reproduce the three-site average values of solar reflectance and thermal emittance attained after 3 years of natural exposure, which the Cool Roof Rating Council (CRRC) uses to rate roofing products sold in the US. This accelerated aging method was applied to 25 products₋single ply membranes, factory and field applied coatings, tiles, modified bitumen cap sheets, and asphalt shingles₋and reproduced in 3 days the CRRC's 3-year aged values of solar reflectance. In conclusion, this accelerated aging method can be used to speed the evaluation and rating of new cool roofing materials.

Evaluation of Ultrasonic and Thermal Nondestructive Evaluation for the Characterization of Aging Degradation in Braided Composite Materials

Science.gov (United States)

Martin, Richard E.

2010-01-01

This paper examines the ability of traditional nondestructive evaluation (NDE) techniques to measure the degradation of braided polymer composite materials subjected to thermal-humidity cycling to simulate aging. A series of braided composite coupons were examined using immersion ultrasonic and pulsed thermography techniques in the as received condition. These same specimens were then examined following extended thermal-humidity cycling. Results of this examination did not show a significant change in the resulting (NDE) signals.

Roofing Materials Assessment: Investigation of Five Metals in Runoff from Roofing Materials.

Science.gov (United States)

Winters, Nancy; Granuke, Kyle; McCall, Melissa

2015-09-01

To assess the contribution of five toxic metals from new roofing materials to stormwater, runoff was collected from 14 types of roofing materials and controls during 20 rain events and analyzed for metals. Many of the new roofing materials evaluated did not show elevated metals concentrations in the runoff. Runoff from several other roofing materials was significantly higher than the controls for arsenic, copper, and zinc. Notably, treated wood shakes released arsenic and copper, copper roofing released copper, PVC roofing released arsenic, and Zincalume® and EPDM roofing released zinc. For the runoff from some of the roofing materials, metals concentrations decreased significantly over an approximately one-year period of aging. Metals concentrations in runoff were demonstrated to depend on a number of factors, such as roofing materials, age of the materials, and climatic conditions. Thus, application of runoff concentrations from roofing materials to estimate basin-wide releases should be undertaken cautiously.

PLANETARY-SCALE STRONTIUM ISOTOPIC HETEROGENEITY AND THE AGE OF VOLATILE DEPLETION OF EARLY SOLAR SYSTEM MATERIALS

Energy Technology Data Exchange (ETDEWEB)

Moynier, Frederic; Podosek, Frank A. [Department of Earth and Planetary Science and McDonnell Center for Space Sciences, Washington University, St. Louis, MO 63130 (United States); Day, James M. D. [Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244 (United States); Okui, Wataru; Yokoyama, Tetsuya [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Bouvier, Audrey [Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455-0231 (United States); Walker, Richard J., E-mail: moynier@levee.wustl.edu, E-mail: fap@levee.wustl.edu, E-mail: jmdday@ucsd.edu, E-mail: rjwalker@umd.edu, E-mail: okui.w.aa@m.titech.ac.jp, E-mail: tetsuya.yoko@geo.titech.ac.jp, E-mail: abouvier@umn.edu [Department of Geology, University of Maryland, College Park, MD 20742 (United States)

2012-10-10

Isotopic anomalies in planetary materials reflect both early solar nebular heterogeneity inherited from presolar stellar sources and processes that generated non-mass-dependent isotopic fractionations. The characterization of isotopic variations in heavy elements among early solar system materials yields important insight into the stellar environment and formation of the solar system, and about initial isotopic ratios relevant to long-term chronological applications. One such heavy element, strontium, is a central element in the geosciences due to wide application of the long-lived {sup 87}Rb-{sup 87}Sr radioactive as a chronometer. We show that the stable isotopes of Sr were heterogeneously distributed at both the mineral scale and the planetary scale in the early solar system, and also that the Sr isotopic heterogeneities correlate with mass-independent oxygen isotope variations, with only CI chondrites plotting outside of this correlation. The correlation implies that most solar system material formed by mixing of at least two isotopically distinct components: a CV-chondrite-like component and an O-chondrite-like component, and possibly a distinct CI-chondrite-like component. The heterogeneous distribution of Sr isotopes may indicate that variations in initial {sup 87}Sr/{sup 86}Sr of early solar system materials reflect isotopic heterogeneity instead of having chronological significance, as interpreted previously. For example, given the differences in {sup 84}Sr/{sup 86}Sr between calcium aluminum inclusions and eucrites ({epsilon}{sup 84}Sr > 2), the difference in age between these materials would be {approx}6 Ma shorter than previously interpreted, placing the Sr chronology in agreement with other long- and short-lived isotope systems, such as U-Pb and Mn-Cr.

Performance and Ageing Robustness of Graphite/NMC Pouch Prototypes Manufactured through Eco-Friendly Materials and Processes.

Science.gov (United States)

Loeffler, Nicholas; Kim, Guk-T; Passerini, Stefano; Gutierrez, Cesar; Cendoya, Iosu; De Meatza, Iratxe; Alessandrini, Fabrizio; Appetecchi, Giovanni B

2017-09-22

Graphite/lithium nickel-manganese-cobalt oxide (NMC), stacked pouch cells with nominal capacity of 15-18 Ah were designed, developed, and manufactured for automotive applications in the frame of the European Project GREENLION. A natural, water-soluble material was used as the main electrode binder, thus allowing the employment of H 2 O as the only processing solvent. The electrode formulations were developed, optimized, and upscaled for cell manufacturing. Prolonged cycling and ageing tests revealed excellent capacity retention and robustness toward degradation phenomena. For instance, above 99 % of the initial capacity is retained upon 500 full charge/discharge cycles, corresponding to a fading of 0.004 % per cycle, and about 80 % of the initial capacity is delivered after 8 months ageing at 45 °C. The stacked soft-packaged cells have shown very reproducible characteristics and performance, reflecting the goodness of design and manufacturing. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulation and experiment of thermal energy management with phase change material for ageing LiFePO4 power battery

International Nuclear Information System (INIS)

Rao Zhonghao; Wang Shuangfeng; Zhang Guoqing

2011-01-01

Highlights: → We study the thermal energy management performance of ageing LiFePO 4 power battery. → 3-D modules of single cell and battery pack are formulated according to the experimental results. → Thermal resistance in the battery cell leaded to an inevitable temperature difference. → It is necessary to improve the thermal conductivity and lower the melting point of phase change material. → Thermal conductivity of phase change material and battery exist an effective proportion. - Abstract: Thermal energy management performance of ageing commercial rectangular LiFePO 4 power batteries using phase change material (PCM) and thermal behavior related to thermal conductivity between the PCM and the cell are discussed in this paper. The heat sources are simplified according to the experimental results of the cells discharged at 35 A (∼5 C). 3-D modules of a single cell and battery pack are formulated, respectively. The results show that the thermal resistance in the cell leads to an inevitable temperature difference. It is necessary to improve the thermal conductivity and to lower the melting point of the PCM for heat transfer enhancement. The PCM with a melting point lower than 45 deg. C will be more effective for heat dissipation, with a desired maximum temperature below 50 deg. C. The temperature difference in the whole unit before PCM melting will be decreased significantly. In addition, a proper k PCM :k c is necessary for a well designed battery thermal energy management system.

Environmental Effects on ISS Materials Aging (1998 to 2008)

Science.gov (United States)

Alred, John; Dasgupta, Rajib; Koontz, Steve; Soares, Carlos; Golden, John

2009-01-01

The performance of ISS spacecraft materials and systems on prolonged exposure to the low- Earth orbit (LEO) space flight are reported in this paper. In-flight data, flight crew observations, and the results of ground-based test and analysis directly supporting programmatic and operational decision-making are described. The space flight environments definitions (both natural and induced) used for ISS design, material selection, and verification testing are shown, in most cases, to be more severe than the actual flight environment accounting, in part, for the outstanding performance of ISS as a long mission duration spacecraft. No significant ISS material or system failures have been attributed to spacecraft-environments interactions. Nonetheless, ISS materials and systems performance data is contributing to our understanding of spacecraft material interactions with the spaceflight environment so as to reduce cost and risk for future spaceflight projects and programs. Orbital inclination (51.6 deg) and altitude (nominally near 360 km) determine the set of natural environment factors affecting the functional life of materials and systems on ISS. ISS operates in an electrically conducting environment (the F2 region of Earth s ionosphere) with well-defined fluxes of atomic oxygen, other charged and neutral ionospheric plasma species, solar UV, VUV, and x-ray radiation as well as galactic cosmic rays, trapped radiation, and solar cosmic rays. The LEO micrometeoroid and orbital debris environment is an especially important determinant of spacecraft design and operations. The magnitude of several environmental factors varies dramatically with latitude and longitude as ISS orbits the Earth. The high latitude orbital environment also exposes ISS to higher fluences of trapped energetic electrons, auroral electrons, solar cosmic rays, and galactic cosmic rays than would be the case in lower inclination orbits, largely as a result of the overall shape and magnitude of the

Aging Mechanisms and Nondestructive Aging Indicator of Filled Cross-linked Polyethylene (XLPE) Exposed to Simultaneous Thermal and Gamma Radiation

Energy Technology Data Exchange (ETDEWEB)

Liu, Shuaishuai; Fifield, Leonard S.; Bowler, Nicola

2018-04-11

Aging mechanisms and a nondestructive aging indicator of filled cross-linked polyethylene (XLPE) cable insulation material used in nuclear power plants (NPPs) are studied. Using various material characterization techniques, likely candidates and functions for the main additives in a commercial filled-XLPE insulation material have been identified. These include decabromodiphenyl ether and Sb2O3 as flame retardants, ZnS as white pigment and polymerized 1,2-dihydro-2,2,4-trimethylquinoline as antioxidant. Gas chromatography-mass spectrometry, differential scanning calorimetry, oxidation induction time and measurements of dielectric loss tangent are utilized to monitor property changes as a function of thermal and radiation exposure of the cable material. Small-molecular-weight hydrocarbons are evolve with gamma radiation aging at 90 °C. The level of antioxidant decreases with aging by volatilization and chemical reaction with free radicals. Thermal aging at 90 °C for 25 days or less causes no observable change to the cross-linked polymer structure. Gamma radiation causes damage to crystalline polymer regions and introduces defects. Dielectric loss tangent is shown to be an effective and reliable nondestructive indicator of the aging severity of the filled-XLPE insulation material.

Toxicity of functional nano-micro zinc oxide tetrapods: impact of cell culture conditions, cellular age and material properties.

Science.gov (United States)

Papavlassopoulos, Heike; Mishra, Yogendra K; Kaps, Sören; Paulowicz, Ingo; Abdelaziz, Ramzy; Elbahri, Mady; Maser, Edmund; Adelung, Rainer; Röhl, Claudia

2014-01-01

With increasing production and applications of nanostructured zinc oxide, e.g., for biomedical and consumer products, the question of safety is getting more and more important. Different morphologies of zinc oxide structures have been synthesized and accordingly investigated. In this study, we have particularly focused on nano-micro ZnO tetrapods (ZnO-T), because their large scale fabrication has been made possible by a newly introduced flame transport synthesis approach which will probably lead to several new applications. Moreover, ZnO-T provide a completely different morphology then classical spherical ZnO nanoparticles. To get a better understanding of parameters that affect the interactions between ZnO-T and mammalian cells, and thus their biocompatibility, we have examined the impact of cell culture conditions as well as of material properties on cytotoxicity. Our results demonstrate that the cell density of fibroblasts in culture along with their age, i.e., the number of preceding cell divisions, strongly affect the cytotoxic potency of ZnO-T. Concerning the material properties, the toxic potency of ZnO-T is found to be significantly lower than that of spherical ZnO nanoparticles. Furthermore, the morphology of the ZnO-T influenced cellular toxicity in contrast to surface charges modified by UV illumination or O2 treatment and to the material age. Finally, we have observed that direct contact between tetrapods and cells increases their toxicity compared to transwell culture models which allow only an indirect effect via released zinc ions. The results reveal several parameters that can be of importance for the assessment of ZnO-T toxicity in cell cultures and for particle development.

Regulatory challenges in the management of aging of structural materials in nuclear power plants

International Nuclear Information System (INIS)

Castelo, C.; Mendoza, C.; Mas, E.; Conde, J. M.

2013-01-01

The article discusses two major pathways by which a regulatory body, and in particular the CSN, may participate in the acquisition of the necessary knowledge on mechanisms of aging of nuclear structural materials: to participate in forums to share operational experience and R and R project, both nationally and internationally. It notes the importance of this participation to carry out its regulatory function based on the knowledge acquired and the unique challenge of transferring that knowledge to rules and guidelines for their application. The article discusses various R and D projects in which the CSN participates directly. It calls for the presence of regulatory bodies in R and D project funded by the EU and the transfer of the results of such projects to codes, standards or guidelines for feasible implementation. (Author)

Materials design and development of functional materials for industry

International Nuclear Information System (INIS)

Asahi, Ryoji; Morikawa, Takeshi; Hazama, Hirofumi; Matsubara, Masato

2008-01-01

It is now well recognized that we are witnessing a golden age of innovation with novel materials, with discoveries that are important for both basic science and industry. With the development of theory along with computing power, quantum materials design-the synthesis of materials with the desired properties in a controlled way via materials engineering on the atomic scale-is becoming a major component of materials research. Computational prediction based on first-principles calculations has helped to find an efficient way to develop materials that are much needed for industry, as we have seen in the successful development of visible-light sensitized photocatalysts and thermoelectric materials. Close collaboration between theory and experiment is emphasized as an essential for success

Catalyst Stability Benchmarking for the Oxygen Evolution Reaction: The Importance of Backing Electrode Material and Dissolution in Accelerated Aging Studies.

Science.gov (United States)

Geiger, Simon; Kasian, Olga; Mingers, Andrea M; Nicley, Shannon S; Haenen, Ken; Mayrhofer, Karl J J; Cherevko, Serhiy

2017-09-18

In searching for alternative oxygen evolution reaction (OER) catalysts for acidic water splitting, fast screening of the material intrinsic activity and stability in half-cell tests is of vital importance. The screening process significantly accelerates the discovery of new promising materials without the need of time-consuming real-cell analysis. In commonly employed tests, a conclusion on the catalyst stability is drawn solely on the basis of electrochemical data, for example, by evaluating potential-versus-time profiles. Herein important limitations of such approaches, which are related to the degradation of the backing electrode material, are demonstrated. State-of-the-art Ir-black powder is investigated for OER activity and for dissolution as a function of the backing electrode material. Even at very short time intervals materials like glassy carbon passivate, increasing the contact resistance and concealing the degradation phenomena of the electrocatalyst itself. Alternative backing electrodes like gold and boron-doped diamond show better stability and are thus recommended for short accelerated aging investigations. Moreover, parallel quantification of dissolution products in the electrolyte is shown to be of great importance for comparing OER catalyst feasibility. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bonding of Glass Ceramic and Indirect Composite to Non-aged and Aged Resin Composite

NARCIS (Netherlands)

Gresnigt, Marco; Ozcan, Mutlu; Muis, Maarten; Kalk, Warner

2012-01-01

Purpose: Since adhesion of the restorative materials to pre-polymerized or aged resin composites presents a challenge to the clinicians, existing restorations are often removed and remade prior to cementation of fixed dental prostheses (FDPs). This study evaluated bond strength of non-aged and aged

Choosing Play Materials for Primary School Children (Ages 6-8)

Science.gov (United States)

Bronson, Martha

2003-01-01

Providing children with a variety of play materials at different levels of challenge and in a variety of interest areas responds to children's individual differences and needs in the classroom. In this book excerpt, the author lists materials for play in the categories social and fantasy; exploration and mastery; music, art, and movement; and…

Material property evaluations of bimetallic welds, stainless steel saw fusion lines, and materials affected by dynamic strain aging

Energy Technology Data Exchange (ETDEWEB)

Rudland, D.; Scott, P.; Marschall, C.; Wilkowski, G. [Battelle Memorial Institute, Columbus, OH (United States)

1997-04-01

Pipe fracture analyses can often reasonably predict the behavior of flawed piping. However, there are material applications with uncertainties in fracture behavior. This paper summarizes work on three such cases. First, the fracture behavior of bimetallic welds are discussed. The purpose of the study was to determine if current fracture analyses can predict the response of pipe with flaws in bimetallic welds. The weld joined sections of A516 Grade 70 carbon steel to F316 stainless steel. The crack was along the carbon steel base metal to Inconel 182 weld metal fusion line. Material properties from tensile and C(T) specimens were used to predict large pipe response. The major conclusion from the work is that fracture behavior of the weld could be evaluated with reasonable accuracy using properties of the carbon steel pipe and conventional J-estimation analyses. However, results may not be generally true for all bimetallic welds. Second, the toughness of austenitic steel submerged-arc weld (SAW) fusion lines is discussed. During large-scale pipe tests with flaws in the center of the SAW, the crack tended to grow into the fusion line. The fracture toughness of the base metal, the SAW, and the fusion line were determined and compared. The major conclusion reached is that although the fusion line had a higher initiation toughness than the weld metal, the fusion-line J-R curve reached a steady-state value while the SAW J-R curve increased. Last, carbon steel fracture experiments containing circumferential flaws with periods of unstable crack jumps during steady ductile tearing are discussed. These instabilities are believed to be due to dynamic strain aging (DSA). The paper discusses DSA, a screening criteria developed to predict DSA, and the ability of the current J-based methodologies to assess the effect of these crack instabilities. The effect of loading rate on the strength and toughness of several different carbon steel pipes at LWR temperatures is also discussed.

Material Resources and Population Health: Disadvantages in Health Care, Housing, and Food Among Adults Over 50 Years of Age

Science.gov (United States)

Soldo, Beth J.; Pagán, José A.; McCabe, John; deBlois, Madeleine; Field, Samuel H.; Asch, David A.; Cannuscio, Carolyn

2009-01-01

Objectives. We examined associations between material resources and late-life declines in health. Methods. We used logistic regression to estimate the odds of declines in self-rated health and incident walking limitations associated with material disadvantages in a prospective panel representative of US adults aged 51 years and older (N = 15 441). Results. Disadvantages in health care (odds ratio [OR] = 1.39; 95% confidence interval [CI] = 1.23, 1.58), food (OR = 1.69; 95% CI = 1.29, 2.22), and housing (OR = 1.20; 95% CI = 1.07, 1.35) were independently associated with declines in self-rated health, whereas only health care (OR = 1.43; 95% CI = 1.29, 1.58) and food (OR = 1.64; 95% CI = 1.31, 2.05) disadvantage predicted incident walking limitations. Participants experiencing multiple material disadvantages were particularly susceptible to worsening health and functional decline. These effects were sustained after we controlled for numerous covariates, including baseline health status and comorbidities. The relations between health declines and non-Hispanic Black race/ethnicity, poverty, marital status, and education were attenuated or eliminated after we controlled for material disadvantage. Conclusions. Material disadvantages, which are highly policy relevant, appear related to health in ways not captured by education and poverty. Policies to improve health should address a range of basic human needs, rather than health care alone. PMID:19890175

Influence of core thickness and artificial aging on the biaxial flexural strength of different all-ceramic materials: An in-vitro study.

Science.gov (United States)

Dikicier, Sibel; Ayyildiz, Simel; Ozen, Julide; Sipahi, Cumhur

2017-05-31

The purpose of this study was to investigate the flexural strength of all-ceramics with varying core thicknesses submitted to aging. In-Ceram Alumina (IC), IPS e.max Press (EM) and Katana (K) (n=40), were selected. Each group contained two core groups based on the core thickness as follows: IC/0.5, IC/0.8, EM/0.5, EM/0.8, K/0.5 and K/0.8 mm in thickness (n=20 each). Ten specimens from each group were subjected to aging and all specimens were tested for strength in a testing machine either with or without being subjected aging. The mean strength of the K were higher (873.05 MPa) than that of the IC (548.28 MPa) and EM (374.32 MPa) regardless of core thickness. Strength values increased with increasing core thickness for all IC, EM and K regardless of aging. Results of this study concluded that strength was not significantly affected by aging. Different core thicknesses affected strength of the all-ceramic materials tested (p<0.05).

Oral Streptococci growth on aging and non-aging esthetic restorations after radiotherapy

International Nuclear Information System (INIS)

Cruz, Adriana D. da; Boscolo, Frab N.; Almeida, Solange M. de; Cogo, Karina; Bergamaschi, Cristiane de C.; Groppo, Francisco C.

2010-01-01

The aim of this study was to examine Streptococcus mutans biofilm growth on both aged and non-aged restorative dental resins, which were submitted to therapeutic irradiation. Sixty-four disks of an esthetic restorative material (Filtek Supreme) were divided into two groups: aged group (AG) and a non-aged group (NAG). Each group was subdivided into four subgroups: non-irradiated and irradiated with 10 Gy, 35 Gy, and 70 Gy. The biofilms were produced by Streptococcus mutans UA159 growing on both AG and NAG surfaces. The colony-forming units per mL (CFU/mL) were evaluated by the ANOVA and the Tukey LSD tests (a=0.05). AG presented smaller amounts of CFU/mL than the NAG before irradiation and after 10 Gy of irradiation (p<0.05). AG irradiated with 35 and 70 Gy showed increased amount of bacterial biofilm when compared to non-irradiated and 10 Gy-irradiated disks (p<0.05). The exposure to ionizing radiation at therapeutic doses promoted changes in bacterial adherence of aged dental restorative material. (author)

Oral Streptococci growth on aging and non-aging esthetic restorations after radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Cruz, Adriana D. da; Boscolo, Frab N.; Almeida, Solange M. de [State University of Campinas (UNICAMP), Piracicaba, SP (Brazil). Dental School. Dept. of Oral Diagnosis; Cogo, Karina; Bergamaschi, Cristiane de C.; Groppo, Francisco C., E-mail: karicogo@hotmail.co [State University of Campinas (UNICAMP), Piracicaba, SP (Brazil). Dental School. Dept. of Physiology

2010-07-01

The aim of this study was to examine Streptococcus mutans biofilm growth on both aged and non-aged restorative dental resins, which were submitted to therapeutic irradiation. Sixty-four disks of an esthetic restorative material (Filtek Supreme) were divided into two groups: aged group (AG) and a non-aged group (NAG). Each group was subdivided into four subgroups: non-irradiated and irradiated with 10 Gy, 35 Gy, and 70 Gy. The biofilms were produced by Streptococcus mutans UA159 growing on both AG and NAG surfaces. The colony-forming units per mL (CFU/mL) were evaluated by the ANOVA and the Tukey LSD tests (a=0.05). AG presented smaller amounts of CFU/mL than the NAG before irradiation and after 10 Gy of irradiation (p<0.05). AG irradiated with 35 and 70 Gy showed increased amount of bacterial biofilm when compared to non-irradiated and 10 Gy-irradiated disks (p<0.05). The exposure to ionizing radiation at therapeutic doses promoted changes in bacterial adherence of aged dental restorative material. (author)

Materials behaviour in PWRs core

International Nuclear Information System (INIS)

Barbu, A.; Massoud, J.P.

2008-01-01

Like in any industrial facility, the materials of PWR reactors are submitted to mechanical, thermal or chemical stresses during particularly long durations of operation: 40 years, and even 60 years. Materials closer to the nuclear fuel are submitted to intense bombardment of particles (mainly neutrons) coming from the nuclear reactions inside the core. In such conditions, the damages can be numerous and various: irradiation aging, thermal aging, friction wear, generalized corrosion, stress corrosion etc.. The understanding of the materials behaviour inside the cores of reactors in operation is a major concern for the nuclear industry and its long term forecast is a necessity. This article describes the main ways of materials degradation without and under irradiation, with the means used to foresee their behaviour using physics-based models. Content: 1 - structures, components and materials: structure materials, nuclear materials; 2 - main ways of degradation without irradiation: thermal aging, stress corrosion, wear; 3 - main ways of degradation under irradiation: microscopic damaging - point defects, dimensional alterations, evolution of mechanical characteristics under irradiation, irradiation-assisted stress corrosion cracking (IASCC), synergies; 4 - forecast of materials evolution under irradiation using physics-based models: primary damage - fast dynamics, primary damage annealing - slow kinetics microstructural evolution, impact of microstructural changes on the macroscopic behaviour, insight on modeling methods; 5 - materials change characterization techniques: microscopic techniques - direct defects observation, nuclear techniques using a particle beam, global measurements, mechanical characterizations; 6 - perspectives. (J.S.)

Book Review: Knowledge in the Age of Digital Capitalism: An Introduction to Cognitive Materialism by Mariano Zukerfeld

Directory of Open Access Journals (Sweden)

Rainer Zimmermann

2018-02-01

Full Text Available Rainer E. Zimmermann reviews Mariano Zukerfeld's Knowledge in the Age of Digital Capitalism. An Introduction to Cognitive Materialism, University of Westminster Press, London, 2017, 272 pp., paperback and open access, gratis e-book. There are several aspects of innovative thoughts in this text as to recent developments, in particular concerning the manifold occasions of more or less hidden layers of exploitation originating in the use of digital technology, and mainly based on un-remunerated activities. All this speaks very much in favour of reading this book; only minor objections have to be made that should not prevent a profitable reading.

PETN Coarsening - Predictions from Accelerated Aging Data

Energy Technology Data Exchange (ETDEWEB)

Maiti, Amitesh [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gee, Richard H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2011-03-30

Ensuring good ignition properties over long periods of time necessitates maintaining a good level of porosity in powders of initiator materials and preventing particle coarsening. To simulate porosity changes of such powder materials over long periods of time a common strategy is to perform accelerated aging experiments over shorter time spans at elevated temperatures. In this paper we examine historical accelerated-aging data on powders of Pentaerythritol Tetranitrate (PETN), an important energetic material, and make predictions for long-term aging under ambient conditions. Lastly, we develop an evaporation-condensation- based model to provide some mechanistic understanding of the coarsening process.

Characterization of vacancy type defects in Electronic Materials by Positron Lifetime and Age-Momentum Correlation Spectroscopy

Science.gov (United States)

Suzuki, Ryoichi; Ohdaira, Toshiyuki

2002-03-01

Positron annihilation spectroscopy is known to be sensitive to vacancy type defects. At the National Institute of Advanced Industrial Science and Technology (AIST) Japan, the authors have developed a measurement system which enables us to perform depth-selective positron annihilation lifetime spectroscopy (PALS) and positron age-momentum correlation (AMOC) spectroscopy with an intense slow positron beam. PALS gives us information on the size of vacancies whereas AMOC gives us information on not only vacancy sizes but also impurities or chemical environments. Using this system, we have carried out defect characterization experiments on various electronic materials, e.g. ion implanted Si, SiO2/Si, MOS, CVD or SOD (spin-on-dielectric) grown low dielectric insulator films, etc.

IAEA Coordinated Research Project on the Establishment of a Material Properties Database for Irradiated Core Structural Components for Continued Safe Operation and Lifetime Extension of Ageing Research Reactors

Energy Technology Data Exchange (ETDEWEB)

Borio Di Tigliole, A.; Schaaf, Van Der; Barnea, Y.; Bradley, E.; Morris, C.; Rao, D. V. H. [Research Reactor Section, Vianna (Australia); Shokr, A. [Research Reactor Safety Section, Vienna (Australia); Zeman, A. [International Atomic Energy Agency, Vienna (Australia)

2013-07-01

Today more than 50% of operating Research Reactors (RRs) are over 45 years old. Thus, ageing management is one of the most important issues to face in order to ensure availability (including life extension), reliability and safe operation of these facilities for the future. Management of the ageing process requires, amongst others, the predictions for the behavior of structural materials of primary components subjected to irradiation such as reactor vessel and core support structures, many of which are extremely difficult or impossible to replace. In fact, age-related material degradation mechanisms resulted in high profile, unplanned and lengthy shutdowns and unique regulatory processes of relicensing the facilities in recent years. These could likely have been prevented by utilizing available data for the implementation of appropriate maintenance and surveillance programmes. This IAEA Coordinated Research Project (CRP) will provide an international forum to establish a material properties Database for irradiated core structural materials and components. It is expected that this Database will be used by research reactor operators and regulators to help predict ageing related degradation. This would be useful to minimize unpredicted outages due to ageing processes of primary components and to mitigate lengthy and costly shutdowns. The Database will be a compilation of data from RRs operators' inputs, comprehensive literature reviews and experimental data from RRs. Moreover, the CRP will specify further activities needed to be addressed in order to bridge the gaps in the new created Database, for potential follow-on activities. As per today, 13 Member States (MS) confirmed their agreement to contribute to the development of the Database, covering a wide number of materials and properties. The present publication incorporates two parts: the first part includes details on the pre-CRP Questionnaire, including the conclusions drawn from the answers received from

IAEA Coordinated Research Project on the Establishment of a Material Properties Database for Irradiated Core Structural Components for Continued Safe Operation and Lifetime Extension of Ageing Research Reactors

International Nuclear Information System (INIS)

Borio Di Tigliole, A.; Schaaf, Van Der; Barnea, Y.; Bradley, E.; Morris, C.; Rao, D. V. H.; Shokr, A.; Zeman, A.

2013-01-01

Today more than 50% of operating Research Reactors (RRs) are over 45 years old. Thus, ageing management is one of the most important issues to face in order to ensure availability (including life extension), reliability and safe operation of these facilities for the future. Management of the ageing process requires, amongst others, the predictions for the behavior of structural materials of primary components subjected to irradiation such as reactor vessel and core support structures, many of which are extremely difficult or impossible to replace. In fact, age-related material degradation mechanisms resulted in high profile, unplanned and lengthy shutdowns and unique regulatory processes of relicensing the facilities in recent years. These could likely have been prevented by utilizing available data for the implementation of appropriate maintenance and surveillance programmes. This IAEA Coordinated Research Project (CRP) will provide an international forum to establish a material properties Database for irradiated core structural materials and components. It is expected that this Database will be used by research reactor operators and regulators to help predict ageing related degradation. This would be useful to minimize unpredicted outages due to ageing processes of primary components and to mitigate lengthy and costly shutdowns. The Database will be a compilation of data from RRs operators' inputs, comprehensive literature reviews and experimental data from RRs. Moreover, the CRP will specify further activities needed to be addressed in order to bridge the gaps in the new created Database, for potential follow-on activities. As per today, 13 Member States (MS) confirmed their agreement to contribute to the development of the Database, covering a wide number of materials and properties. The present publication incorporates two parts: the first part includes details on the pre-CRP Questionnaire, including the conclusions drawn from the answers received from the MS

Predictive characterization of aging and degradation of reactor materials in extreme environments. Final report, December 20, 2013 - September 20, 2017

Energy Technology Data Exchange (ETDEWEB)

Qu, Jianmin [Northwestern Univ., Evanston, IL (United States)

2017-09-20

Understanding of reactor material behavior in extreme environments is vital not only to the development of new materials for the next generation nuclear reactors, but also to the extension of the operating lifetimes of the current fleet of nuclear reactors. To this end, this project conducted a suite of unique experimental techniques, augmented by a mesoscale computational framework, to understand and predict the long-term effects of irradiation, temperature, and stress on material microstructures and their macroscopic behavior. The experimental techniques and computational tools were demonstrated on two distinctive types of reactor materials, namely, Zr alloys and high-Cr martensitic steels. These materials are chosen as the test beds because they are the archetypes of high-performance reactor materials (cladding, wrappers, ducts, pressure vessel, piping, etc.). To fill the knowledge gaps, and to meet the technology needs, a suite of innovative in situ transmission electron microscopy (TEM) characterization techniques (heating, heavy ion irradiation, He implantation, quantitative small-scale mechanical testing, and various combinations thereof) were developed and used to elucidate and map the fundamental mechanisms of microstructure evolution in both Zr and Cr alloys for a wide range environmental boundary conditions in the thermal-mechanical-irradiation input space. Knowledge gained from the experimental observations of the active mechanisms and the role of local microstructural defects on the response of the material has been incorporated into a mathematically rigorous and comprehensive three-dimensional mesoscale framework capable of accounting for the compositional variation, microstructural evolution and localized deformation (radiation damage) to predict aging and degradation of key reactor materials operating in extreme environments. Predictions from this mesoscale framework were compared with the in situ TEM observations to validate the model.

Predictive characterization of aging and degradation of reactor materials in extreme environments. Final report, December 20, 2013 - September 20, 2017

International Nuclear Information System (INIS)

Qu, Jianmin

2017-01-01

Understanding of reactor material behavior in extreme environments is vital not only to the development of new materials for the next generation nuclear reactors, but also to the extension of the operating lifetimes of the current fleet of nuclear reactors. To this end, this project conducted a suite of unique experimental techniques, augmented by a mesoscale computational framework, to understand and predict the long-term effects of irradiation, temperature, and stress on material microstructures and their macroscopic behavior. The experimental techniques and computational tools were demonstrated on two distinctive types of reactor materials, namely, Zr alloys and high-Cr martensitic steels. These materials are chosen as the test beds because they are the archetypes of high-performance reactor materials (cladding, wrappers, ducts, pressure vessel, piping, etc.). To fill the knowledge gaps, and to meet the technology needs, a suite of innovative in situ transmission electron microscopy (TEM) characterization techniques (heating, heavy ion irradiation, He implantation, quantitative small-scale mechanical testing, and various combinations thereof) were developed and used to elucidate and map the fundamental mechanisms of microstructure evolution in both Zr and Cr alloys for a wide range environmental boundary conditions in the thermal-mechanical-irradiation input space. Knowledge gained from the experimental observations of the active mechanisms and the role of local microstructural defects on the response of the material has been incorporated into a mathematically rigorous and comprehensive three-dimensional mesoscale framework capable of accounting for the compositional variation, microstructural evolution and localized deformation (radiation damage) to predict aging and degradation of key reactor materials operating in extreme environments. Predictions from this mesoscale framework were compared with the in situ TEM observations to validate the model.

Dielectric materials for electrical engineering

CERN Document Server

Martinez-Vega, Juan

2013-01-01

Part 1 is particularly concerned with physical properties, electrical ageing and modeling with topics such as the physics of charged dielectric materials, conduction mechanisms, dielectric relaxation, space charge, electric ageing and life end models and dielectric experimental characterization. Part 2 concerns some applications specific to dielectric materials: insulating oils for transformers, electrorheological fluids, electrolytic capacitors, ionic membranes, photovoltaic conversion, dielectric thermal control coatings for geostationary satellites, plastics recycling and piezoelectric poly

Ultrasonic assessment of early age property development in hydrating cementitious materials

Science.gov (United States)

Wang, Xiaojun

The internal structure (microstructure) of cementitious materials, such as cement paste, mortar and concrete, evolves over time because of cement hydration. The microstructure of the cementitious phase plays a very important role in determining the strength, the mechanical properties and the long-term durability of cementitious materials. Therefore any understanding of the strength gain and the long-term durability of cementitious materials requires a proper assessment of the microstructure of its cementitious phase. Current methods for evaluating the microstructure of the cement are invasive and primarily laboratory-based. These methods are not conducive for studying the pore structure changes in the first few hours after casting since the changes in microstructure occur on a time scale that is an order of magnitude faster than the time required for sample preparation. The primary objective of the research presented in this thesis is to contribute towards advancing the current state-of-the-art in assessing the microstructure of cementitious systems. An ultrasonic wave reflection technique which allows for real-time assessment of the porosity and the elastic modulus of cementitious materials is developed. The test procedure for monitoring changes in the amplitude of horizontally polarized ultrasonic shear waves from the surface of hydrating cement paste is presented. A theoretical framework based on a poro-elastic idealization of the hydrating cementitious material is developed for interpreting the ultrasonic reflection data. The poro-elastic representation of hydrating cementitious material is shown to provide simultaneous, realistic estimates of porosity and shear modulus for hydrating cement paste and mortar through setting and early strength gain. The porosity predicted by the poro-elastic representation is identical to the capillary water content within the cement paste predicted by Powers' model. The shear modulus of the poro-elastic skeleton was compares

Materials for the 21st century

CERN Document Server

Segal, David

2017-01-01

The book is a general text that shows how materials can contribute to solving problems facing nations in the 21st century. It is illustrated with diverse applications and highlights the potential of existing materials for everyday life, healthcare and the economies of nations. There are 13 chapters and a glossary of 500 materials with their descriptions, historical development, their use or potential use and a range of references. Specific areas include synthetic polymers (e.g. nylon), natural polymers (e.g. proteins, cellulose) and the role of materials in the development of digital computers and in healthcare. Solid-state lighting, energy supplies in the 21st century, disruptive technologies and intellectual property, in particular patents, are discussed. The book concludes by asking how the 21st century will be characterised. Will it be the Silicon Age, Genomic Age or New Polymer Age, as examples?

Review of the status of nondestructive measurement techniques to quantify material property degradation due to aging and planning for further evaluation

International Nuclear Information System (INIS)

Boyd, D.M.; Bruemmer, S.M.; Green, E.R.; Schuster, G.J.; Simonen, E.P.

1989-01-01

The materials used in nuclear reactors are inspected periodically during the service life of the power plant to detect degradation that might occur. These inspections follow the rules specified in Section XI of the ASME Boiler and Pressure Vessel Code. These inspections are designed to detect service-induced failure mechanisms. This program is designed not to look at the detection of defects but the marking of nondestructive measurements to quantify the material properties that a defect may reside in or the incipient condition(s) that may initiate a defect. This program is intended to provide an assessment of the technologies that are available to quantify with nondestructive measurements material properties or material property changes related to degradation due to aging of structural components in light water reactors. In addition, a program plan will be developed that describes the work necessary to create adequate engineering data bases for demonstrating and validating prototypic systems for making these measurements. The main thrust this year has been an extensive review of literature and an assessment of the technology. The second major activity was the planning of a workshop to bring together 30 leading experts in materials and NDE to discuss the state-of-the-art and to address where future work should go

Review of the status of nondestructive measurement techniques to quantify material property degradation due to aging and planning for further evaluation

International Nuclear Information System (INIS)

Doctor, S.R.; Boyd, D.M.; Bruemmer, S.M.; Green, E.R.; Schuster, G.J.; Simonen, E.P.

1989-01-01

The materials used in nuclear reactors are inspected periodically during the service life of the power plant to detect degradation that might occur. These inspections follow the rules specified in Section XI of the ASME Boiler and Pressure Vessel Code. These inspections are designed to detect service-induced failure mechanisms. This program is designed not to look at the detection of defects but the making of nondestructive measurements to quantify the material properties that a defect may reside in or the incipient condition(s) that may initiate a defect. This program is intended to provide an assessment of the technologies that are available to quantify with nondestructive measurements material properties or material property changes related to degradation due to aging of structural components in light water reactors. In addition, a program plan will be developed that describes the work necessary to create adequate engineering data bases for demonstrating and validating prototypic systems for making these measurements. The main thrust this year has been an extensive review of literature and an assessment of the technology. The second major activity was the planning of a workshop to bring together 30 leading experts in materials and nondestructive evaluation to discuss the state-of-the-art and to address where future work should go

ALPHA SPECTROMETRIC EVALUATION OF SRM-995 AS A POTENTIAL URANIUM/THORIUM DOUBLE TRACER SYSTEM FOR AGE-DATING URANIUM MATERIALS

Energy Technology Data Exchange (ETDEWEB)

Beals, D.

2011-12-06

Uranium-233 (t{sub 1/2} {approx} 1.59E5 years) is an artificial, fissile isotope of uranium that has significant importance in nuclear forensics. The isotope provides a unique signature in determining the origin and provenance of uranium-bearing materials and is valuable as a mass spectrometric tracer. Alpha spectrometry was employed in the critical evaluation of a {sup 233}U standard reference material (SRM-995) as a dual tracer system based on the in-growth of {sup 229}Th (t{sub 1/2} {approx} 7.34E3 years) for {approx}35 years following radiochemical purification. Preliminary investigations focused on the isotopic analysis of standards and unmodified fractions of SRM-995; all samples were separated and purified using a multi-column anion-exchange scheme. The {sup 229}Th/{sup 233}U atom ratio for SRM-995 was found to be 1.598E-4 ({+-} 4.50%) using recovery-corrected radiochemical methods. Using the Bateman equations and relevant half-lives, this ratio reflects a material that was purified {approx} 36.8 years prior to this analysis. The calculated age is discussed in contrast with both the date of certification and the recorded date of last purification.

Cable aging management

International Nuclear Information System (INIS)

Anandkumaran, A.; Sedding, H.

2012-01-01

Worldwide, due to the age of the majority of nuclear generating stations significant attention is being paid to the condition of the major components, e.g., reactor, steam generator, turbine generator, transformer, etc., with respect to relicensing and life extension. However, there is recognition that cable systems are critical to the safe, reliable and economic operation of nuclear power plants. Consequently, there is great interest in ageing management of low and medium voltage cables in the nuclear environment. Successful implementation of such programs requires an understanding of how the materials associated with cables and their accessories behave under normal operating and accident conditions. However, there is also a great need to determine the actual condition of the materials and systems in order to make rational decisions on whether or not to replace cables to ensure long term assurance of reliable operation. This proposed contribution describes an approach to cable ageing management of low and medium voltage cables based on measurements of material and electrical properties obtained in the laboratory and in the field. The effectiveness of various chemical, mechanical and electrical test methods are discussed in the context of, • Cable configuration, i.e., low or medium voltage, shielded or unshielded • Material type, i.e., PVC, XLPE, EPR, etc., • Ageing stress, i.e., electrical, thermal, radiation, thermal plus radiation, etc. These factors are key to identifying the most appropriate test method (or methods) to enable understanding of the current condition of the cable. While electrical test methods, e.g., ac withstand testing, partial discharge and various dielectric loss measurement techniques have been found effective for medium voltage cables, they are of very limited use on low voltage cables that constitute the majority of cables in nuclear power plants. This limited effectiveness is due to the lack of a well defined ground plane that is a

Forensic engineering of advanced polymeric materials Part IV: Case study of oxo-biodegradable polyethylene commercial bag - Aging in biotic and abiotic environment.

Science.gov (United States)

Musioł, Marta; Rydz, Joanna; Janeczek, Henryk; Radecka, Iza; Jiang, Guozhan; Kowalczuk, Marek

2017-06-01

The public awareness of the quality of environment stimulates the endeavor to safe polymeric materials and their degradation products. The aim of the forensic engineering case study presented in this paper is to evaluate the aging process of commercial oxo-degradable polyethylene bag under real industrial composting conditions and in distilled water at 70°C, for comparison. Partial degradation of the investigated material was monitored by changes in molecular weight, thermal properties and Keto Carbonyl Bond Index and Vinyl Bond Index, which were calculated from the FTIR spectra. The results indicate that such an oxo-degradable product offered in markets degrades slowly under industrial composting conditions. Even fragmentation is slow, and it is dubious that biological mineralization of this material would occur within a year under industrial composting conditions. The slow degradation and fragmentation is most likely due to partially crosslinking after long time of degradation, which results in the limitation of low molecular weight residues for assimilation. The work suggests that these materials should not be labeled as biodegradable, and should be further analyzed in order to avoid the spread of persistent artificial materials in nature. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reliability of structural materials in nuclear industry

International Nuclear Information System (INIS)

Pinard Legry, G.

1996-01-01

The reliability of nuclear installations is a fundamental point for the exploitation of nuclear energy. It requires an extensive knowledge of the behaviour of materials in the operating conditions and during the expected service life of the installations. In nuclear power plants multiple risks of failure can exist and are expressed by corrosion and deformation phenomena or by modification in the mechanical characteristics of materials. The knowledge of the evolution with time of a given material requires to take into account the data relative to the material itself, to its environment and to the physical conditions of this environment. The study of materials aging needs a more precise knowledge of the kinetics of phenomena at any scale and of their interactions, and a micro- or macro-modeling of their behaviour during long periods of time. This paper gives an overview of the aging phenomena that occur in the structural materials involved in PWR and fast neutron reactors: thermal aging, generalized corrosion, corrosion under constraint, intergranular corrosion, crack growth under loading, wear, irradiation etc.. (J.S.)

Relative age and age sequence of fractions of soil organic matter

International Nuclear Information System (INIS)

Scharpenseel, H.W.

1975-01-01

Natural radiocarbon measurements on soil fractions provide information regarding the chances of separating the ''old biologically inert carbon'' out of samples of recent soil material. Beyond this, the relative fraction ages are scrutinized for the sequential order of the origin of the fractions within the biosynthetic reaction chain of soil humic matter. Among all fractions compared (classic humic matter fractionation by alkali and acid treatment; successive extraction with organic solvents of increasing polarity; separation according to particle size by Sephadex gel filtration; hydrolysis residue) the 6 n HCl hydrolysis residue shows the most consistent significant age increment. Repeated exhaustive hydrolysis treatment of the same sample material is still pending. All other fraction types indicate an age pattern under strong predetermination by method of origin, e.g., existence or lack of hydromorphy, without an evident enrichment of the ''old biologically inert carbon''. Among the organic extracts, no persistent age hierarchy is noticeable, whereas the classical fractions follow an age sequence mainly parallel to an increase of the molecular weight. Hymatomelanic acids appear rejuvenated by relics of recent carbon derived from the extractant ethanol. Grey humic acids are older than the brown humic acids, humines from fully terrestrial soil environment are older than humic acids, while in hydromorphic soils, cold alkali insoluble young C-compounds seem to be conserved which are liable to falsify rejuvenation of the humines

Active ageing technologies

DEFF Research Database (Denmark)

Lassen, Aske Juul

In the recent decade the concept of active aging has become important in the Western hemisphere. The World Health Organization and The European Union have staged active aging as a core policy area and initiated programs of physical activity, independence and prolonged working lives among...... the elderly. As part of this rearticulation of old age, many new technologies take form. This paper uses a wide concept of technologies (devices, regimes, strategies and ways of doing) and argues that technologies form active aging subjectivities, and on the other hand, that these subjectivities...... in their socio-material practices form active aging. Hence, active aging is a mutual entanglement (Callon and Rabeharisoa 2004) between technologies, practices and subjectivities. The paper is based on four months of participant observations and 17 in-depth interviews with elderly persons conducted at three...

FY 2017 – Thermal Aging Effects on Advanced Structural Materials

Energy Technology Data Exchange (ETDEWEB)

Li, Meimei [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, K [Argonne National Lab. (ANL), Argonne, IL (United States); Chen, Wei-Ying [Argonne National Lab. (ANL), Argonne, IL (United States)

2017-08-01

This report provides an update on the evaluation of the effect of thermal aging on tensile properties of existing laboratory-sized heats of Alloy 709 austenitic stainless steel and the completion of effort on the thermal aging effect on the tensile properties of optimized G92 ferritic-martensitic steel. The report is a Level 3 deliverable in FY17 (M3AT-17AN1602081), under the Work Package AT-17AN160208, “Advanced Alloy Testing - ANL” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

Dielectric characterization of high-performance spaceflight materials

Science.gov (United States)

Kleppe, Nathan; Nurge, Mark A.; Bowler, Nicola

2015-03-01

As commercial space travel increases, the need for reliable structural health monitoring to predict possible weaknesses or failures of structural materials also increases. Monitoring of these materials can be done through the use of dielectric spectroscopy by comparing permittivity or conductivity measurements performed on a sample in use to that of a pristine sample from 100 μHz to 3 GHz. Fluctuations in these measured values or of the relaxation frequencies, if present, can indicate chemical or physical changes occurring within the material and the possible need for maintenance/replacement. In this work, we establish indicative trends that occur due to changes in dielectric spectra during accelerated aging of various high-performance polymeric materials: ethylene vinyl alcohol (EVOH), Poly (ether ether ketone) (PEEK), polyphenylene sulfide (PPS), and ultra-high molecular weight polyethylene (UHMWPE). Uses for these materials range from electrical insulation and protective coatings to windows and air- or space-craft parts that may be subject to environmental damage over long-term operation. Samples were prepared by thermal exposure and, separately, by ultraviolet/water-spray cyclic aging. The aged samples showed statistically-significant trends of either increasing or decreasing real or imaginary permittivity values, relaxation frequencies, conduction or the appearance of new relaxation modes. These results suggest that dielectric testing offers the possibility of nondestructive evaluation of the extent of age-related degradation in these materials.

Age Discrimination and the FAA Age 60 Rule. Hearing before the Select Committee on Aging. House of Representatives, Ninety-Ninth Congress, First Session.

Science.gov (United States)

Congress of the U.S., Washington, DC. House Select Committee on Aging.

This document presents witness testimonies and related materials from a Congressional hearing called to examine the mandatory retirement age of 60 for airline pilots. In opening remarks, Congressmen Roybal and Pepper question this ruling, citing productivity of older workers and the lack of data to support any specific age for mandatory…

A Comparative Study on Wear Properties of As Cast, Cast Aged and Forge Aged A356 Alloy with Addition of Grain Refiner and/or Modifier

Directory of Open Access Journals (Sweden)

D.G. Mallapur

2015-03-01

Full Text Available In the present work, a comparative wear behavior study of three categories of materials viz, as cast, cast aged (casting followed by T6 and forge aged (forging followed by T6 has been investigated. Neither melt treatment nor solid state processing (like aging and forging seems to be altering the wear behavior of the materials drastically. Cast aged A356 materials exhibit higher wear resistance compared to as cast and forge aged A356 materials. Further, it was observed that cast aged samples register lower coefficient of friction compared to other samples. It is also noted that the difference in wear behavior is revealed only at conditions of higher load, higher speed and longer sliding distance of testing. At lower regimes the difference is marginal. Among cast aged samples, ones treated with combined addition exhibit better wear resistance compared to other materials. Samples treated with combined addition register lowest coefficient of friction followed by samples treated with Sr, those with B, those with Ti and untreated ones. Abrasive wear mechanism is found to be operative in the regime of higher loading and higher velocity of sliding. Adhesive wear mechanism seems to be dominating the wear process at the lower regime of load and velocity of sliding.

Strain ageing in welds of nuclear pressure vessels

International Nuclear Information System (INIS)

Otterberg, R.; Karlsson, C.

1979-01-01

Static and dynamic strain ageing have been investigated on submerged-arc welds and repair welds from plates of the pressure vessel steel A 533B. The results permit the determination of the worst strain ageing conditions existing in a nuclear pressure vessel. Static strain ageing was investigated by means of data from tension tests, hardness measurements and Charpy-V impact properties for prestrained and aged material for ageing temperatures from room temperature to 350 deg C and ageing times up to 1000h. Dynamic strain ageing was investigated by tensile tests up to 350 deg C at different strain rates. At the most static strain ageing was found to increase the impact transition temperature from -75 deg C in the as-received condition to -55 deg C after prestraining and ageing for the plate material, from -35 to -10 deg C for the submerged arc weld and from -90 to -40 deg C for the repair weld. Approximately 10 deg C of the deleterious effect is due to the effect of ageing for the two former materials whereas the corresponding figure for the repair weld amounts to 35 deg C. The dynamic strain ageing is strongest at very low strain rates at temperatures just below 300 deg C. The effect of strain ageing can be reduced by stress relief heat treatment or by other means decreasing the content of nitrogen in solution. (author)

Electronic materials

CERN Document Server

Kwok, H L

2010-01-01

The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

Do Bacteria Age?

Indian Academy of Sciences (India)

Bacteria are thought to be examples of organisms that do not age. They divide by .... carry genetic material to the next generation through the process of reproduction; they are also .... molecules, and modified proteins. This report revealed that ...

Age and Stress Prediction

Science.gov (United States)

2000-01-01

Genoa is a software product that predicts progressive aging and failure in a variety of materials. It is the result of a SBIR contract between the Glenn Research Center and Alpha Star Corporation. Genoa allows designers to determine if the materials they plan on applying to a structure are up to the task or if alternate materials should be considered. Genoa's two feature applications are its progressive failure simulations and its test verification. It allows for a reduction in inspection frequency, rapid design solutions, and manufacturing with low cost materials. It will benefit the aerospace, airline, and automotive industries, with future applications for other uses.

Shaping old age: Innovation partnerships, senior centres and billiards tables as active ageing technologies

DEFF Research Database (Denmark)

Lassen, Aske Juul

2017-01-01

During the past decade active ageing has been positioned as a solution to the problem of global ageing. While the scientific, economic and even moral arguments for pursuing a more active old age has been many, the integration of active ageing in everyday practices face challenges. This chapter...... explores the ways that active ageing policies become part of everyday practices, by proposing the concept of active ageing technologies. Active ageing technologies are material and immaterial condensations of knowledge that form old age in specific ways. Through the cases of an innovation partnership, two...... activity centres and a billiards table, the author explores how active ageing policies are transformed in practice. The chapter draws on an ethnographic study of active ageing conducted at the two activity centres, as well as the author’s participation in the innovation partnership. The author uses...

Summary of JAPEIC age program

International Nuclear Information System (INIS)

Miyoshi, S.; Maeda, N.; Yamaguchi, A.

1992-01-01

Japan Power Engineering and Inspection Corporation (JAPEIC) is a statutory foundation charged with responsibility of enhancing thermal and nuclear power plant quality. JAPEIC performs construction and pre-service inspections as well as periodic inspections of many types of power plants including nuclear, gas turbine and internal combustion systems. In 1987 a research center was established to permit the systematic examination of advanced inspection technologies. One of the Structural Materials in Use for commercial Nuclear Power Plants provides the link to this workshop. The project is also referred to as the Aging General Evaluation (AGE) project. The AGE project is a six year, multi-task effort addressing material condition monitoring. One set of tasks emphasizes instrumentation simulation tasks to aid in application and utilization. All tasks are in their initial phases. The program is described in this paper

The natural aging of austenitic stainless steels irradiated with fast neutrons

Science.gov (United States)

Rofman, O. V.; Maksimkin, O. P.; Tsay, K. V.; Koyanbayev, Ye. T.; Short, M. P.

2018-02-01

Much of today's research in nuclear materials relies heavily on archived, historical specimens, as neutron irradiation facilities become ever more scarce. These materials are subject to many processes of stress- and irradiation-induced microstructural evolution, including those during and after irradiation. The latter of these, referring to specimens "naturally aged" in ambient laboratory conditions, receives far less attention. The long and slow set of rare defect migration and interaction events during natural aging can significantly change material properties over decadal timescales. This paper presents the results of natural aging carried out over 15 years on austenitic stainless steels from a BN-350 fast breeder reactor, each with its own irradiation, stress state, and natural aging history. Natural aging is shown to significantly reduce hardness in these steels by 10-25% and partially alleviate stress-induced hardening over this timescale, showing that materials evolve back towards equilibrium even at such a low temperature. The results in this study have significant implications to any nuclear materials research program which uses historical specimens from previous irradiations, challenging the commonly held assumption that materials "on the shelf" do not evolve.

The effect of aging on the fracture toughness of esthetic restorative materials.

Science.gov (United States)

Bagheri, Rafat; Azar, Mohammad R; Tyas, Martin J; Burrow, Michael F

2010-06-01

To compare the fracture toughness (KIc) of tooth-colored restorative materials based on a four-point bending; to assess the effect of distilled water and a resin surface sealant (G-Coat Plus) on the resistance of the materials to fracture. Specimens were prepared from six materials: Quix Fil; Dyract (Dentsply), Freedom (SDI), Fuji VII (GC), Fuji IX (GC); Fuji II LC (GC). Fuji II LC and Fuji IX were tested both with and without applying G-Coat Plus (GC). The specimens were divided into the three groups which were conditioned in distilled water at 37 degrees C for 48 hours, 4 and 8 weeks. The specimens were loaded in a four-point bending test using a universal testing machine. The maximum load to specimen failure was recorded and the fracture toughness calculated. There were significant differences among most of the materials (P G-Coat Plus affected Fuji II LC positively while it had no effect on the Fuji IX.

Aging Depth Test of Rubber Blocks by Accelerated Thermal Oxidation Test

International Nuclear Information System (INIS)

Park, Junhee; Choun, Young-Sun; Kim, Min Kyu

2015-01-01

In this study, the accelerated thermal oxidation tests of rubber block were performed to investigate the aging depth of rubber bearing. From the tests, it was found the critical aging depth in rubber block. Also the property variation of rubber was investigated along the depth. The deterioration pattern from the aging depth tests was found from surface to inside and the critical aging depth was to be about 10 mm. The analytical model for rubber bearing with aging can be developed based on the relationship between the property variation and aging depth investigated from this study. The mechanical properties of rubber bearings were changed with time. Because the aging effect of rubber material was generally higher than that of other structure materials it is needed that the aging properties of seismically isolators should be evaluated to ensure the safety of seismically isolated nuclear power plants (NPPs) over the lifetime. NRC and ASCE required the tests of seismically isolators for investigating the aging properties. JNES also required the seismic response analysis for the seismically isolated NPPs when the properties of seismically isolators were extremely changed. If the aging properties of seismically isolators such as rubber bearings are evaluated by analysis the analytical model of seismically isolators should be developed considering aging effect of rubber material. From the previous research, it was reported that the behavior of aged rubber material mainly affected by temperature and oxidation. The material properties between surface and inside can be different by the oxidation of rubber. Therefore, the aging depth should be investigated for exactly evaluating the seismic behavior of aged rubber bearing. The aging depth of rubber baring was not influenced by the size of seismically isolators but environment condition. Therefore, the detail analysis considering aging depth was not required for NPPs with large seismically isolators. But the seismic response

Thermal ageing of steels; from expertise and understanding of the ageing mechanisms to a maintenance strategy for operating nuclear power plants

International Nuclear Information System (INIS)

Bezdikian, G.; Ould, P.

2004-01-01

Some parts of reactor coolant circuit on Nuclear PWR power plants, elbows on primary circuit, are made in cast duplex stainless steel material. It is now identify that the mechanical characteristic of this material should be decrease under thermal ageing mainly after a long time in operation in at reactor coolant circuit temperature conditions. The sensitiveness to the thermal ageing of these components is in relation with chemical composition and the ferrite content, especially the grade of Chromium equivalent (Ceq %Cr + %Si + %Mo). In the context of justification to maintain in operation on the plants these cat duplex components, an important programme of expertises was carried out on cast elbows after removing on the plants during the Steam Generators replacements (SGR). Several expertises, performed in the objective to understand the thermal ageing phenomenon and mechanism on cast components in service on plants, were permit to validate the prediction formulas established from a large database and programme in laboratories. The expertises were based on a lot of metallurgical, mechanical and chemical characteristics of components in operation Small Angle Neutrons Scattering (SANS), Thermal Electric Power (TEP), micro hardness and toughness measurement on small specimens from boat sample (CT10-5) The expertise carried out on one SG inlet elbows from DAMPIERRE, removed a during SGR after 100000 h in operation is shown, the toughness values are very high compared to the prediction formulas. The TEP measurements performed on the specimen cut off on two elbows and the ingots of the same material aged in laboratory in furnace, are very coherent; it is confirmed that this methodology is a good indicator to follow the ageing characteristic of material. The results of expertises on aged material are a mean of validation of the methodology applied on the file of demonstration of maintaining in operation of cast duplex stainless steel sensitive to thermal ageing. So the

Skeletal Aging and Osteoporosis Biomechanics and Mechanobiology

CERN Document Server

2013-01-01

The focus of this book is on mechanical aspects of skeletal fragility related to aging and osteoporosis. Topics include: Age-related changes in trabecular structure and strength; age-related changes in cortical material properties; age-related changes in whole-bone structure; predicting bone strength and fracture risk using image-based methods and finite element analysis; animal models of osteoporosis and aging; age-related changes in skeletal mechano responsiveness; exercise and physical interventions for osteoporosis.

Influence of different litter materials on cecal microbiota colonization in broiler chickens.

Science.gov (United States)

Torok, V A; Hughes, R J; Ophel-Keller, K; Ali, M; Macalpine, R

2009-12-01

A chicken growth study was conducted to determine if litter type influenced gut microbiota and performance in broilers. Seven bedding materials were investigated and included soft and hardwood sawdust, softwood shavings, shredded paper, chopped straw, rice hulls, and reused softwood shavings. Microbial profiling was done to investigate changes in cecal bacterial communities associated with litter material and age. Cecal microbiota were investigated at 14 and 28 d of age (n = 12 birds/litter material). At both ages, the cecal microbiota of chickens raised on reused litter was significantly (P litter materials, except softwood shavings at d 28. Cecal microbiota was also significantly different between birds raised on shredded paper and rice hulls at both ages. Age had a significant influence on cecal microbiota composition regardless of litter material. Similarity in cecal microbial communities among birds raised on the same litter treatment was greater at 28 d of age (29 to 40%) than at 14 d of age (25 to 32%). Bird performance on the different litter materials was measured by feed conversion ratio, live weight, and feed intake. Significant (P litter materials. However, no significant (P > 0.05) differences were observed in feed conversion ratio among birds raised on any of the 7 different litter materials at either 14 or 28 d of age. The type of litter material can influence colonization and development of cecal microbiota in chickens. Litter-induced changes in the gut microbiota may be partially responsible for some of the significant differences observed in early rates of growth; therefore, litter choice may have an important role in poultry gut health particularly in the absence of in-feed antibiotics.

Kevlar 49/Epoxy COPV Aging Evaluation

Science.gov (United States)

Sutter, James K.; Salem, Jonathan L.; Thesken, John C.; Russell, Richard W.; Littell, Justin; Ruggeri, Charles; Leifeste, Mark R.

2008-01-01

NASA initiated an effort to determine if the aging of Kevlar 49/Epoxy composite overwrapped pressure vessels (COPV) affected their performance. This study briefly reviews the history and certification of composite pressure vessels employed on NASA Orbiters. Tests to evaluate overwrap tensile strength changes compared 30 year old samples from Orbiter vessels to new Kevlar/Epoxy pressure vessel materials. Other tests include transverse compression and thermal analyses (glass transition and moduli). Results from these tests do not indicate a noticeable effect due to aging of the overwrap materials.

LWR aging management using a proactive approach to control materials degradation

International Nuclear Information System (INIS)

Bond, L.J.; Doctor, S.R.; Cumblidge, S.E.; Bruemmer, S.M.; Taylor, W.B.; Hull, A.B.; Malik, S.N.

2009-01-01

Material issues can be the limiting factor for the operation of nuclear power plants. There is growing interest in new and improved philosophies and methodologies for plant life management (PLiM), which include the migration from reliance on periodic inservice inspection to include condition-based maintenance. A further step in the development of plant management is the move from proactive responses based on ISI to become proactive, through the investigation of the potential for implementation of a proactive management of materials degradation (PMMD) program and its potential impact on the management of LWRs. (author)

Accelerated optical polymer aging studies for LED luminaire applications

Science.gov (United States)

Estupiñán, Edgar; Wendling, Peter; Kostrun, Marijan; Garner, Richard

2013-09-01

There is a need in the lighting industry to design and implement accelerated aging methods that accurately simulate the aging process of LED luminaire components. In response to this need, we have built a flexible and reliable system to study the aging characteristics of optical polymer materials, and we have employed it to study a commercially available LED luminaire diffuser made of PMMA. The experimental system consists of a "Blue LED Emitter" and a working surface. Both the temperatures of the samples and the optical powers of the LEDs are appropriately characterized in the system. Several accelerated aging experiments are carried out at different temperatures and optical powers over a 90 hour period and the measured transmission values are used as inputs to a degradation model derived using plausibility arguments. This model seems capable of predicting the behavior of the material as a function of time, temperature and optical power. The model satisfactorily predicts the measured transmission values of diffusers aged in luminaires at two different times and thus can be used to make application recommendations for this material. Specifically, at 35000 hours (the manufacturer's stated life of the luminaire) and at the typical operational temperature of the diffuser, the model predicts a transmission loss of only a few percent over the original transmission of the material at 450 nm, which renders this material suitable for this application.

Aging characteristics of containment building and sensitivity on ultimate pressure capacity

International Nuclear Information System (INIS)

Seo, Jeong Moon; Choun, Young Sun; Choi, In Kil; Ha, Jae Joo

1998-03-01

For the reliable safety assessment of the containment building, structural and material conditions can be investigated in detail and pertinent assessment technologies have to be established. Also, an understanding on the aging-related degradations for the construction materials is required to predict long-term structural safety of the containment building. For the development of reliable aging prediction models, an extensive data base system related to aging properties of the containment building has to be prepared. The objectives of this research are to develop aging models representing long-term degradation of materials and a structural performance assessment program for containment building considering aging-related degradation. According to the results of sensitivity analysis, as the mechanical properties of the constituent materials degrade, the ultimate pressure capacity of containment building may decrease and severe damage may occur around the mid-level of the containment wall. (author). 28 refs., 11 tabs., 36 figs

Effect of shelf aging on vibration transmissibility of anti-vibration gloves

Science.gov (United States)

SHIBATA, Nobuyuki

2017-01-01

Anti-vibration gloves have been used in real workplaces to reduce vibration transmitted through hand-held power tools to the hand. Generally materials used for vibration attenuation in gloves are resilient materials composed of certain synthetic and/or composite polymers. The mechanical characteristics of the resilient materials used in anti-vibration gloves are prone to be influenced by environmental conditions such as temperature, humidity, and photo-irradiation, which cause material degradation and aging. This study focused on the influence of shelf aging on the vibration attenuation performance of air-packaged anti-vibration gloves following 2 yr of shelf aging. Effects of shelf aging on the vibration attenuation performance of anti-vibration gloves were examined according to the Japan industrial standard JIS T8114 test protocol. The findings indicate that shelf aging induces the reduction of vibration attenuation performance in air-packaged anti-vibration gloves. PMID:28978817

Shelf life prediction of radiation sterilized polymeric materials

International Nuclear Information System (INIS)

Sandford, Craig; Woo, Lecon

1988-01-01

The functional properties of many polymers employed in medical disposables are unaffected by sterilizing doses of ionizing radiation. However, some materials (PVC, polypropylene, cellulosics, etc.) undergo undesirable changes which continue to occur for the shelf life of the product. In many cases, conventional accelerated aging techniques do not accurately predict the real time properties of the materials. As real time aging is not generally practical, it has become necessary to develop accelerated aging techniques which can predict the functional properties of a material for the shelf life of the product. This presentation will address issues involved in developing these tests. Real time physical property data is compared to data generated by various acceleration methods. (author)

Development of an aging integrator for uranium-0.75 weight percent titanium alloy part aging control

International Nuclear Information System (INIS)

Howington, L.C.

1977-12-01

An instrumentation system (Aging Integrator) has been developed to provide more precise control of the heat-treatment process used on uranium-0.75 wt.% titanium alloy material. The Aging Integrator calculates the integral of a predetermined aging function to control the aging period in the heat-treatment process. This control was employed to compensate for discrepancies caused by variations in heatup times, furnace-control fluctuations, and disagreement as to the temperature at which aging actually starts. Although the Aging Integrator hardware has been installed and satisfactorily tested on a production-area furnace, sufficient data to estimate a statistically sound aging integration function will not be available for approximately one year

Transitional Thermal Creep of Early Age Concrete

DEFF Research Database (Denmark)

Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Freiesleben Hansen, Per

1999-01-01

Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete which includes the transitional thermal effect. The model govern both early age concrete and hardened concrete. The development of the material properties in the model are assumed to depend on the hydration process...... termed the microprestresses, which reduces the stiffness of the concrete and increase the creep rate. The aging material is modelled in an incremental way reflecting the hydration process in which new layers of cement gel solidifies in a stress free state and add stiffness to the material. Analysis...

Material aging and degradation detection and remaining life assessment for plant life management

International Nuclear Information System (INIS)

Ramuhalli, P.; Henager, C.H. Jr.; Griffin, J.W.; Meyer, R.M.; Coble, J.B.; Pitman, S.G.; Bond, L.J.

2012-01-01

One of the major factors that may impact long-term operations is structural material degradation. Detecting materials degradation, estimating the remaining useful life (RUL) of the component, and determining approaches to mitigating the degradation are important from the perspective of long-term operations. In this study, multiple nondestructive measurement and monitoring methods were evaluated for their ability to assess the material degradation state. Metrics quantifying the level of damage from these measurements were defined and evaluated for their ability to provide estimates of remaining life of the component. An example of estimating the RUL from nondestructive measurements of material degradation condition is provided. (author)

Aging Studies of VCE Dismantlement Returns

Energy Technology Data Exchange (ETDEWEB)

Letant, S; Alviso, C; Pearson, M; Albo, R; Small, W; Wilson, T; Chinn, S; Maxwell, R

2011-10-17

VCE is an ethylene/vinyl acetate/vinyl alcohol terpolymer binder for filled elastomers which is designed to accept high filler loadings. Filled elastomer parts consist of the binder (VCE), a curing agent (Hylene MP, diphenol-4-4{prime}-methylenebis(phenylcarbamate)), a processing aid (LS, lithium stearate), and filler particles (typically 70% fraction by weight). The curing of the filled elastomer parts occurs from the heat-activated reaction between the hydroxyl groups of VCE with the Hylene MP curing agent, resulting in a cross-linked network. The final vinyl acetate content is typically between 34.9 and 37.9%, while the vinyl alcohol content is typically between 1.27 and 1.78%. Surveillance data for this material is both scarce and scattered, complicating the assessment of any aging trends in systems. In addition, most of the initial surveillance efforts focused on mechanical properties such as hardness and tensile strength, and chemical information is therefore lacking. Material characterization and aging studies had been performed on previous formulations of the VCE material but the Ethylene Vinyl Acetate (EVA) starting copolymer is no longer commercially available. New formulations with replacement EVA materials are currently being established and will require characterization as well as updated aging models.

Modeling Creep Processes in Aging Polymers

Science.gov (United States)

Olali, N. V.; Voitovich, L. V.; Zazimko, N. N.; Malezhik, M. P.

2016-03-01

The photoelastic method is generalized to creep in hereditary aging materials. Optical-creep curves and mechanical-creep or optical-relaxation curves are used to interpret fringe patterns. For materials with constant Poisson's ratio, it is sufficient to use mechanical- or optical-creep curves for this purpose

Micromechanical modelling of heterogeneous materials in transient conditions: contributions for the study of the ageing of structural components under service

International Nuclear Information System (INIS)

Masson, R.

2010-01-01

The modelling of the mechanical behaviour of structural materials is increasingly based on microstructural parameters. Within this framework, homogenisation methods have the advantage of providing deductive methods which, starting from the properties and space distribution of each constituent, deduce the effective properties of the heterogeneous material. Nevertheless, many applications make still difficult the use of homogenisation methods. It is in particular the case of structural materials presenting elastic-viscoplastic behaviours and subjected to both non-monotone and ageing loadings. To progress on the treatment by homogenisation of these useful situations constitutes precisely the main idea of the various contributions presented in this work.For linear elasticity, new expressions for the computation of the Eshelby tensor are first of all established in order to improve the efficiency of homogenisation methods usually used. Always for linear behaviours but now viscoelastic, various approximations associated with the use of the theorem of correspondence are studied and compared. The equivalence of one of these approximations (the so-called 'collocation method') with an internal variables formulation of the effective behaviour is shown. This internal variables formulation leads to exact results in some situations and strongly simplifies the treatment of ageing linear viscoelastic behaviours. In the case of elastic-viscoplastic behaviours, is added to the previous difficulty (viscoelastic coupling) that of the treatment of nonlinear behaviour. Comparisons made between various families of estimates make it possible to determine the effects of the various approximations needed to deal with these nonlinearities. An improvement is also proposed and implemented in a particular case while the extension of this internal variable formulation to nonlinear behaviours is discussed. Finally, full-field computations of microstructures are also tackled by considering the

Understanding and Managing Aging of Spent Nuclear Fuel and Facility Components in Wet Storage

International Nuclear Information System (INIS)

Johnson, A. B.

2007-01-01

Storage of nuclear fuel after it has been discharged from reactors has become the leading spent fuel management option. Many storage facilities are being required to operate longer than originally anticipated. Aging is a term that has emerged to focus attention on the consequences of extended operation on systems, structures, and components that comprise the storage facilities. The key to mitigation of age-related degradation in storage facilities is to implement effective strategies to understand and manage aging of the facility materials. A systematic approach to preclude serious effects of age-related degradation is addressed in this paper, directed principally to smaller facilities (test and research reactors). The first need is to assess the materials that comprise the facility and the environments that they are subject to. Access to historical data on facility design, fabrication, and operation can facilitate assessment of expected materials performance. Methods to assess the current condition of facility materials are summarized in the paper. Each facility needs an aging management plan to define the scope of the management program, involving identification of the materials that need specific actions to manage age-related degradation. For each material identified, one or more aging management programs are developed and become part of the plan Several national and international organizations have invested in development of comprehensive and systematic approaches to aging management. A method developed by the US Nuclear Regulatory Commission is recommended as a concise template to organize measures to effectively manage age-related degradation of storage facility materials, including the scope of inspection, surveillance, and maintenance that is needed to assure successful operation of the facility over its required life. Important to effective aging management is a staff that is alert for evidence of materials degradation and committed to carry out the aging

Investigation of plutonium abundance and age analysis

Energy Technology Data Exchange (ETDEWEB)

Huailong, Wu; Jian, Gong; Fanhua, Hao [China Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry

2007-06-15

Based on spectra analysis software, all of the plutonium material peak counts are analyzed. Relatively efficiency calibration is done by the non-coupling peaks of {sup 239}Pu. By using the known isotopes half life and yield, the coupling peaks counts are allocated by non-coupling peaks, consequently the atom ratios of each isotope are gotten. The formula between atom ratio and abundance or age is deduced by plutonium material isotopes decay characteristic. And so the abundance and age of plutonium material is gotten. After some re- peat measurements for a plutonium equipment are completed, a comparison between our analysis results and PC-FRAM and the owner's reference results are done. (authors)

The role of aging in resolving the ferrocyanide safety issue

International Nuclear Information System (INIS)

Babad, H.; Meacham, J.E.; Simpson, B.C.; Cash, R.J.

1993-08-01

A chemical process called aging, in which stored ferrocyanide waste could be dissolved and dispersed among waste tanks, or destroyed by radiolysis and hydrolysis, has been proposed at the Hanford Site. This paper summarizes the results of applied research, characterization, and modeling activities on Hanford Site ferrocyanide waste material that support the existence of a chemical aging mechanism. Test results from waste simulants and actual waste tank materials are presented and compared with theoretical estimates. Chemical and energetic behavior of the materials are the key indicators of destruction or dispersion. Screening experiments on vendor-prepared sodium nickel ferrocyanide and the initial results from core sampling support the concept that aging of ferrocyanide is taking place in the waste tanks at the Hanford Site. This report defines the concept of waste aging and explains the role that aging could play in resolving the Hanford Site ferrocyanide safety issue

Where and How Do Aging Processes Take Place in Everyday Life? Answers From a New Materialist Perspective

Directory of Open Access Journals (Sweden)

Grit Höppner

2018-04-01

Full Text Available In the last decade, the focus of studies on age and aging has fundamentally changed from biological to symbolic, discursive, and cultural phenomena. Currently, the most studied topic in material gerontology is the materiality of age and aging in the context of everyday life. Scholars in this area have thus been making an important contribution to a material understanding of aging processes. As we understand them, however, both social constructivist and material gerontological concepts reach their limit when it comes to the questions of where and how aging processes actually take place in everyday life. In order to answer these two questions, we review social constructivist ideas with a particular focus on the “doing age” concept and material gerontological assumptions regarding human subjects, their material environments, and their relations. We then suggest rethinking bodily limitations and agencies addressed by scholars in the field of new materialism. The aim is to develop a new materialist-inspired understanding of aging processes that helps to reconstruct the material-discursive co-production of aging processes. These processes are deployed as mutual entanglements of materiality and meaning as well as of humans and non-human agency. This approach emphasizes the decentralization of the human actor and thus helps to map the material-discursive complexity of aging processes as relational co-products of humans and non-humans in everyday life.

Ageing management of concrete structure

International Nuclear Information System (INIS)

Parthipan, P.; Ramaprasad, G.S.; Senthil, R.

2006-01-01

It is a generally accepted fact that while designing a concrete structure the durability parameters of construction materials should be evaluated as carefully as possible like other properties such as mechanical, physical and chemical properties. No material is inherently durable as result of environmental interaction with microstructure and consequently, the properties of the materials change with time due to weathering action, chemical attack, abrasion or any mode of degradation. The main cause of ageing on structure, water, which is primary for both creation and destruction on many natural materials. In porous materials, water creates different types of physical and chemical process of degradation. The water movement through porous materials are controlled by the permeability of the respective materials. The rate of deterioration is affected by type of concentration of ions present in the water and chemical deposition of materials. Controlling weathering action, chemical attack, abrasion and selecting good quality construction material and methods of construction can increase the service life of the structure. (author)

Thermophysical properties of hydrophobised lime plasters - The influence of ageing

Science.gov (United States)

Pavlíková, Milena; Zemanová, Lucie; Pavlík, Zbyšek

2017-07-01

The building envelope is a principal responsible for buildings energy loses. Lime plasters as the most popular finishing materials of historical buildings and culture monuments influence the thermal behaviour as well as construction material of masonry. On this account, the effect of ageing on the thermophysical properties of a newly designed lime plasters containing hydrophobic admixture is analysed in the paper. For the comparative purposes, the reference lime plaster is tested. The ageing is accelerated with controlled carbonation process to simulate the final plasters properties. Basic characterization of the tested materials is done using bulk density, matrix density, and porosity measurements. Thermal conductivity and volumetric heat capacity are experimentally assessed using a transient impulse method. The obtained data revealed the significant changes of the both studied thermal parameters in the dependence on plasters composition and age. The assessed material parameters will be stored in a material database, where will find use as an input data for computational modelling of heat transport in this type of porous building materials and evaluation of energy-savings and sustainability issues.

Radiation Effects on Spacecraft Structural Materials

International Nuclear Information System (INIS)

Wang, Jy-An J.; Ellis, Ronald J.; Hunter, Hamilton T.; Singleterry, Robert C. Jr.

2002-01-01

Research is being conducted to develop an integrated technology for the prediction of aging behavior for space structural materials during service. This research will utilize state-of-the-art radiation experimental apparatus and analysis, updated codes and databases, and integrated mechanical and radiation testing techniques to investigate the suitability of numerous current and potential spacecraft structural materials. Also included are the effects on structural materials in surface modules and planetary landing craft, with or without fission power supplies. Spacecraft structural materials would also be in hostile radiation environments on the surface of the moon and planets without appreciable atmospheres and moons around planets with large intense magnetic and radiation fields (such as the Jovian moons). The effects of extreme temperature cycles in such locations compounds the effects of radiation on structural materials. This paper describes the integrated methodology in detail and shows that it will provide a significant technological advance for designing advanced spacecraft. This methodology will also allow for the development of advanced spacecraft materials through the understanding of the underlying mechanisms of material degradation in the space radiation environment. Thus, this technology holds a promise for revolutionary advances in material damage prediction and protection of space structural components as, for example, in the development of guidelines for managing surveillance programs regarding the integrity of spacecraft components, and the safety of the aging spacecraft. (authors)

Research note: Mapping spatial patterns in sewer age, material, and proximity to surface waterways to infer sewer leakage hotspots

Science.gov (United States)

Hopkins, Kristina G.; Bain, Daniel J.

2018-01-01

Identifying areas where deteriorating sewer infrastructure is in close proximity to surface waterways is needed to map likely connections between sewers and streams. We present a method to estimate sewer installation year and deterioration status using historical maps of the sewer network, parcel-scale property assessment data, and pipe material. Areas where streams were likely buried into the sewer system were mapped by intersecting the historical stream network derived from a 10-m resolution digital elevation model with sewer pipe locations. Potential sewer leakage hotspots were mapped by identifying where aging sewer pipes are in close proximity (50-m) to surface waterways. Results from Pittsburgh, Pennsylvania (USA), indicated 41% of the historical stream length was lost or buried and the potential interface between sewers and streams is great. The co-location of aging sewer infrastructure (>75 years old) near stream channels suggests that 42% of existing streams are located in areas with a high potential for sewer leakage if sewer infrastructure fails. Mapping the sewer-stream interface provides an approach to better understand areas were failing sewers may contribute a disproportional amount of nutrients and other pathogens to surface waterways.

Uranium age determination - Separation and analysis of 230Th and 231Pa

International Nuclear Information System (INIS)

Morgenstern, A.; Apostolidis, C.; Mayer, K.; Wallenius, M.

2002-01-01

Full text: In recent years several incidents involving illicit trafficking and smuggling of nuclear material, radioactive sources and radioactively contaminated materials have raised growing public concern about criminal acts involving nuclear materials. Consequently, research efforts in nuclear forensic science have been intensified in order to develop and improve methods for the identification of the nature and origin of seized materials. Information obtained from the analysis of unknown nuclear materials is of key importance in order to aide authorities that are in charge of developing fast and appropriate response action. For the identification of nuclear materials various sample characteristics are of relevance, including isotopic composition, the content of chemical impurities, material properties and the date of production. Information on the production date, respectively the 'age' of nuclear materials, will also be of key importance in other fields of nuclear science, i.e. for the verification of a Fissile Materials Cut-Off Treaty (FMCT) in order to distinguish freshly produced materials from 'old' excess weapons materials. The age of nuclear materials may also be of relevance under a strengthened safeguards regime to reveal clandestine production of weapons usable materials, i.e. the separation of plutonium or production of highly enriched uranium (HEU). The age dating of plutonium samples has been described in detail for bulk samples as well as for particles. In this work we focused on the age determination of uranium materials of different uranium enrichment. The radioactive decay of the uranium isotopes provides a chronometer that is inherent to the material, in particular the mother/daughter pairs 234 U/ 230 Th and 235 U/ 231 Pa can be advantageously used. Due to the relatively long half-lives of 234 U (2.46·10 5 years) and 235 U (7.04·10 8 years) only minute amounts of daughter nuclides are growing in, therefore both separation of Th and Pa from

Nordic and Celtic: religion in southern Scandinavia during the late bronze age and early iron age

Directory of Open Access Journals (Sweden)

Marianne Görman

1990-01-01

Full Text Available By means of modern archeological research it is today possible to gain much information even from non-written material, This paper covers the late bronze age and early iron age, ca. 1000 B.C. —O. It is based on material from Denmark, the Southwest of Sweden, and the Southeast of Norway. This region formed a cultural unity since the sea bound the area together. Our main sources of knowledge of Nordic religion during this time span are votive offerings and rock-carvings. During the bronze age and early iron age the Nordic peasant population had intensive contacts with the Southeastern and Centralparts of Europe. A great quantity of imported objects bear evidence of widespread connections. The inhabitants of the Nordic area not only brought home objects, but also ideas and religious conceptions. This is clearly reflected in the iconography. The cultures with which connections were upheld and from which ideas were introduced were those of Hallstatt and La Tène. They were both Celtic iron age cultures prospering in Central Europe at the same time as the late bronze age and early iron age in the Nordic area. This means that the new symbols in the Nordic area come from a Celtic environment. Consequently, Celtic religion such as it may be found in the pre-Roman period, can clarify the meaning of the conceptions, linked with these symbols.

Influence of Thermal Aging on Primary Water Stress Corrosion Cracking of Cast Duplex Stainless Steels

International Nuclear Information System (INIS)

Yamada, T.; Totsuka, N.; Nakajima, N.; Arioka, K.; Negishi, K.

2002-01-01

In order to evaluate the SCC (stress corrosion cracking) susceptibility of cast duplex stainless steels which are used for the main coolant piping material of pressurized water reactors (PWRs), the slow strain rate test (SSRT) and the constant load test (CLT) were performed in simulated PWR primary water at 360 C. The main coolant piping materials contain ferrite phase with ranging from 8 to 23 % and its mechanical properties are affected by long time thermal aging. The 23% ferrite material was prepared for test as the maximum ferrite content of main coolant pipes in Japanese PWRs. The brittle fracture in the non-aged materials after SSRT is mainly caused by quasi-cleavage fracture in austenitic phase. On the other hand, a mixture of quasi-cleavage fracture in austenite and ferrite phases was observed on long time aged material. Also on CLT, (2 times σ y ), after 3,000 hours exposure, microcracks were observed on the surface of non-aged and aged for 10,000 hours at 400 C materials. The crack initiation site of CLT is similar to that of SSRT. The SCC susceptibility of the materials increases with aging time. It is suggested that the ferrite hardening with aging affect SCC susceptibility of cast duplex stainless steels. (authors)

Translucency of Zirconia Ceramics before and after Artificial Aging.

Science.gov (United States)

Walczak, Katarzyna; Meißner, Heike; Range, Ursula; Sakkas, Andreas; Boening, Klaus; Wieckiewicz, Mieszko; Konstantinidis, Ioannis

2018-03-11

The aging of zirconia ceramics (Y-TZP) is associated with tetragonal to monoclinic phase transformation. This change in microstructure may affect the optical properties of the ceramic. This study examines the effect of aging on the translucency of different zirconia materials. 120 disc-shaped specimens were fabricated from four zirconia materials: Cercon ht white, BruxZir Solid Zirconia, Zenostar T0, Lava Plus (n = 30 per group). Accelerated aging was performed in a steam autoclave (134°C, 0.2 MPa, 5 hours). CIELab coordinates (L*, a*, b*) and luminous reflectance (Y) were measured with a spectrophotometer before and after aging. Contrast ratio (CR) and translucency parameter (TP) were calculated from the L*, a*, b*, and Y tristimulus values. The general linear model (Bonferroni adjusted) was used to compare both parameters before and after aging, as well as between the different zirconia materials (p ≤ 0.05). CR and TP differed significantly before and after aging in all groups tested. Before aging, Zenostar T showed the highest and Lava Plus showed the lowest translucency. After aging, Cercon ht and Zenostar T showed the highest and BruxZir and Lava Plus the lowest translucency. Aging reduced the translucency in all specimens tested. Furthermore, translucency differed between the zirconia brands tested. Nevertheless, the differences were below the detectability threshold of the human eye. The aging process can influence the translucency and thus the esthetic outcome of zirconia restorations; however, the changes in translucency were minimal and probably undetectable by the human eye. © 2018 by the American College of Prosthodontists.

Can superabsorbent polymers mitigate shrinkage in cementitious materials blended with supplementary cementitious materials?

DEFF Research Database (Denmark)

Snoeck, Didier; Jensen, Ole Mejlhede; De Belie, Nele

2016-01-01

A promising way to mitigate autogenous shrinkage in cementitious materials with a low water-to-binder ratio is internal curing by the use of superabsorbent polymers. Superabsorbent polymers are able to absorb multiple times their weight in water and can be applied as an internal water reservoir...... to induce internal curing and mitigation of self-desiccation. Their purposefulness has been demonstrated in Portland cement pastes with and without silica fume. Nowadays, fly ash and blast-furnace slag containing binders are also frequently used in the construction industry. The results on autogenous...... shrinkage in materials blended with fly ash or blast-furnace slag remain scarce, especially after one week of age. This paper focuses on the autogenous shrinkage by performing manual and automated shrinkage measurements up to one month of age. Without superabsorbent polymers, autogenous shrinkage...

Mechanisms of aging and fatigue in ferroelectrics

Energy Technology Data Exchange (ETDEWEB)

Genenko, Yuri A. [Sonderforschungsbereich 595, Institut für Materialwissenschaft, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany); Glaum, Julia [Department of Materials Science and Engineering, University of New South Wales, Sydney (Australia); Hoffmann, Michael J. [Institut für keramische Werkstoffe, Haid-und-Neu Str. 7, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Albe, Karsten, E-mail: albe@mm.tu-darmstadt.de [Sonderforschungsbereich 595, Institut für Materialwissenschaft, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany)

2015-02-15

Highlights: • Experiments on aging and fatigue of bulk ferroelectrics are thoroughly reviewed. • Lead-based PZT and lead-free BNT–BT and KNN materials are covered. • Various fatigue regimes and factors are classified. • Defect associate formation and alignment are analyzed by density functional theory. • Emerging of internal bias field is studied within drift-diffusion approach. - Abstract: A comprehensive review of aging and fatigue phenomena in bulk polycrystalline ferroelectrics is presented. Three material classes are covered, namely the most widely used Pb[Zr{sub 1−x}Ti{sub x}]O{sub 3} (PZT) ceramics and lead-free materials, including those based on bismuth sodium titanate Bi{sub 1/2}Na{sub 1/2}TiO{sub 3} (BNT) and alkali niobate [K{sub x}Na{sub 1−x}]NbO{sub 3} (KNN). Aging is studied in poled and unpoled states both experimentally and theoretically. The variety of different loading regimes for fatigue includes DC electric field, unipolar, sesquipolar and bipolar cycling and all these differently combined with mechanical loading at different frequencies and temperatures. The role of device geometries and electrode materials is addressed and models describing charge migration and defect dipole re-orientation are discussed in the context of recent experimental studies.

Mechanisms of aging and fatigue in ferroelectrics

International Nuclear Information System (INIS)

Genenko, Yuri A.; Glaum, Julia; Hoffmann, Michael J.; Albe, Karsten

2015-01-01

Highlights: • Experiments on aging and fatigue of bulk ferroelectrics are thoroughly reviewed. • Lead-based PZT and lead-free BNT–BT and KNN materials are covered. • Various fatigue regimes and factors are classified. • Defect associate formation and alignment are analyzed by density functional theory. • Emerging of internal bias field is studied within drift-diffusion approach. - Abstract: A comprehensive review of aging and fatigue phenomena in bulk polycrystalline ferroelectrics is presented. Three material classes are covered, namely the most widely used Pb[Zr 1−x Ti x ]O 3 (PZT) ceramics and lead-free materials, including those based on bismuth sodium titanate Bi 1/2 Na 1/2 TiO 3 (BNT) and alkali niobate [K x Na 1−x ]NbO 3 (KNN). Aging is studied in poled and unpoled states both experimentally and theoretically. The variety of different loading regimes for fatigue includes DC electric field, unipolar, sesquipolar and bipolar cycling and all these differently combined with mechanical loading at different frequencies and temperatures. The role of device geometries and electrode materials is addressed and models describing charge migration and defect dipole re-orientation are discussed in the context of recent experimental studies

Mobility and Well-being in Old Age

DEFF Research Database (Denmark)

Siren, Anu Kristiina; Hakamies-Blomqvist, Liisa

2009-01-01

This study, using focus group material, explored how independent mobility and personal wellbeing in old age are interconnected and which elements of mobility are the most essential for well-being by examining the way seniors talk about mobility and adapting to age-related mobility restrictions...

Material Fracture Characterization and Toughness Improving Technology Developments

International Nuclear Information System (INIS)

Lee, Bong Sang; Kim, M. C.; Lee, H. J. and others

2005-04-01

Reactor pressure boundary components including pressure vessel and piping are facing a severe aging condition that can degrade the physical-mechanical properties under neutron irradiation, high temperature, high pressure, and corrosive environments. In order to increase the safety of nuclear power plants, it is inevitable to improve the credibility and capability of evaluation technology based on the quantitative fracture mechanics for aging assessment of reactor components. Irradiation embrittlement is the primary aging mechanism of reactor pressure vessel and various techniques have been developed to predict the aging characteristics by using only small volume of irradiated materials. Material database of the domestic structural steels for KSNP's under reactor environments must be very important to play a role in developing an advanced material, in improving the safety of nuclear components, and also in expanding the nuclear industry abroad. This research project has been focused on developing an advanced technology of testing and analysis in the fracture mechanical point of view as well as acquiring test data and improving the performance of nuclear structural steels

Structural aging program -- a summary of activities, results, and conclusions

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

1997-01-01

Research has been conducted by the Oak Ridge National Laboratory to address aging management of nuclear power plant concrete structures. The purpose was to identify potential structural safety issues and acceptance criteria for use in continued service assessments. Primary program accomplishments have included formulation of a Structural Materials Information Center that contains data and information on the time variation of material properties under the influence of pertinent environmental stressors and aging factors for 144 materials, an aging assessment methodology to identify critical structures and degradation factors that can potentially impact their performance, guidelines and evaluation criteria for use in condition assessments of reinforced concrete structures, and a reliability-based methodology for current condition assessments and estimations of future performance of reinforced concrete nuclear power plant structures. In addition, the Structural Aging Program conducted in-depth evaluations of several nondestructive evaluation and repair-related technologies to develop guidance on their applicability

Ageing of research reactors

International Nuclear Information System (INIS)

Ciocanescu, M.

2001-01-01

Historically, many of the research institutions were centred on a research reactor facility as main technological asset and major source of neutrons for research. Important achievements were made in time in these research institutions for development of nuclear materials technology and nuclear safety for nuclear energy. At present, ageing of nuclear research facilities among these research reactors and ageing of staff are considerable factors of reduction of competence in research centres. The safe way of mitigation of this trend deals with ageing management by so called, for power reactors, Plant Life Management and new investments in staff as investments in research, or in future resources of competence. A programmatic approach of ageing of research reactors in correlation with their actual and future utilisation, will be used as a basis for safety evaluation and future spending. (author)

Materials and fabrication requirements for APWR systems

International Nuclear Information System (INIS)

Boothby, R.M.; Hippsley, C.A.; Gorton, O.K.; Garwood, S.J.

1995-01-01

Materials specifications for advanced pressurized water-cooled reactor (APWR) systems are generally based on existing designs, with improved materials and fabrication procedures being developed to counter known degradation effects. In this paper, materials ageing and degradation mechanisms in PWR primary circuit pressure boundary components (i.e. the reactor pressure vessel (RPV), control rod drive mechanisms (CRDMs), coolant piping, coolant pump casing, pressurizer, and steam generators) are reviewed. Important degradation mechanisms include irradiation embrittlement of the RPV, thermal ageing embrittlement of ferritic (e.g. the pressurizer) and cast austenitic (e.g. coolant pump casing and pipe elbows) steel components and environmentally assisted cracking of steam generator tubing and CRDM penetrations. Improved materials specifications and component design and fabrication issues affecting the integrity of the pressure boundary are discussed in the light of these materials problems. Improved fabrication procedures adopted for Sizewell B, such as the utilization of ring forgings to eliminate axial welds in the RPV and steam generator shells and the use of one-piece castings for coolant pump casings, provide a benchmark against which other APWR designs may be judged. (author)

Initial laboratory studies into the chemical and radiological aging of organic materials in underground storage tanks at the Hanford Complex

International Nuclear Information System (INIS)

Samuels, W.D.; Camaioni, D.M.; Babad, H.

1994-01-01

The underground storage tanks at the Hanford Complex contain wastes generated over many years from plutonium production and recovery processes, and mixed wastes from radiological degradation processes. The chemical changes of the organic materials used in the extraction processes have a direct bearing on several specific safety issues, including potential energy releases from these tanks. The major portion of organic materials that have been added to the tanks consists of tributyl phosphate, dibutyl phosphate, butyl alcohol, hexone (methyl isobutyl ketone), normal paraffin hydrocarbons (NPH), ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriadetic acid (HEDTA), other complexants, and lesser quantities of ion exchange polymers and minor organic compounds. A study of how thermal and radiological processes that may have changed the composition of organic tanks constituents has been initiated after a review of the open literature revealed little information was available about the rates and products of these processes under basic pH conditions. This paper will detail the initial findings as they relate to gas generation, e.g. H 2 , CO, NH 3 , CH 4 , and to changes in the composition of the organic and inorganic components brought about by ''Aging'' processes

Effect of aging on the bioavailability and fractionation of arsenic in soils derived from five parent materials in a red soil region of Southern China

International Nuclear Information System (INIS)

Wang, Yanan; Zeng, Xibai; Lu, Yahai; Su, Shiming; Bai, Lingyu; Li, Lianfang; Wu, Cuixia

2015-01-01

The effects of aging time and soil parent materials on the bioavailability and fractionations of arsenic (As) in five red soils were studied. The results indicated that As bioavailability in all soils decreased during aging, especially with a sharp decline occurring in the first 30 days. After aging for 360 days, the highest available As concentration, which accounted for 12.3% of the total, was observed in soils derived from purple sandy shale. While 2.67% was the lowest proportion of the available As in soils derived from quaternary red clay. Furthermore, the best fit of the available As changing with aging time was obtained using the pseudo-second-order model (R"2 = 0.939–0.998, P < 0.05). Notably, Al oxides played a more crucial role (R"2 = 0.89, P<0.05) than did Fe oxides in controlling the rate of As aging. The non-specially and specially absorbed As constituted the primary forms of available As. - Highlights: • The soil derived from purple sandy shale had a relatively higher risk of As toxicity for agricultural production. • The best fit of the variations of available As during the aging time was obtained using the pseudo-second-order model. • Al oxides played a more crucial role than did Fe oxides in controlling the rate of As aging. - Al oxides played a more crucial role than did Fe oxides in controlling the rate of As aging in these red soils.

In-plant natural versus artificial aging study

International Nuclear Information System (INIS)

Shaw, M.

1989-01-01

A few years ago, cable specimens and small electrical components were placed in the reactor buildings of several operating nuclear plants in the United States. Temperature and radiation at the specimen locations are being monitored during the life of the plants. Measured physical properties of materials removed periodically during planned outages over the next 10 to 30 years will be compared with properties of artificially aged materials in identical specimens to assess artificial aging practice. This will also lead to improved lifetime predictions for cables and equipment. The study is being performed by the University of Connecticut's Institute for Materials Science in collaboration with U. S. utilities under the sponsorship of the Electric Power Research Institute (EPRI). Cofunding is being provided by Northeast Utilities and Detroit Edison. This paper gives the status of the study, along with some preliminary results

Effect of alternative aging and accident simulations on polymer properties

International Nuclear Information System (INIS)

Bustard, L.D.; Chenion, J.; Carlin, F.; Alba, C.; Gaussens, G.; LeMeur, M.

1985-05-01

The influence of accident irradiation, steam, and chemical spray exposures on the behavior of twenty-three age-preconditioned polymer sample sets (twenty-one different materials) has been investigated. The test program varied the following conditions: (1) Accident simulations of irradiation and thermodynamic (steam and chemical spray) conditions were performed both sequentially and simultaneously. (2) Accident thermodynamic (steam and chemical spray) exposures were performed both with and without air present during the exposures. (3) Sequential accident irradiations were performed both at 28 0 C and 70 0 C. (4) Age preconditioning was performed both sequentially and simultaneously. (5) Sequential aging irradiations were performed both at 27 0 C and 70 0 C. (6) Sequential aging exposures were performed using two sequences: (1) thermal followed by irradiation and (2) irradiation followed by thermal. We report both general trends applicable to a majority of the tested materials as well as specific results for each polymer. Our data base consists of ultimate tensile properties at the completion of the accident exposure for three XLPO and XLPE, five EPR and EPDM, two CSPE (HYPALON), one CPE, one VAMAC, one polydiallylphtalate, and one PPS material. We also report bend test results at completion of the accident exposures for two TEFZEL materials and permanent set after compression results for three EPR, one VAMAC, one BUNA N, one SILICONE, and one VITON material

Dating of Uranium Materials by Using Combination of ICP-MS and SIMS

International Nuclear Information System (INIS)

Stebelkov, Y.; Aleshin, M.; Elantyev, I.; Grachev, A.; Zhizhin, K.; Stebelkov, V.

2015-01-01

The age of nuclear and some other radioactive materials can be determined undoubtedly by using ICP-MS techniques. But it can be correct if only one nuclear or another radioactive material is presented in analyzed sample and no isotope-chronograph presented in background particles in significant quantities. For particle analysis, which can be implemented by using SIMS, these restrictions are not valid. Practically one particle always characterizes only one material and does not contain background isotopes-chronographs. But age determination is based on the result of measuring of the content ratio of Th230 and U234. The difference of ionization coefficients of uranium and thorium and dependence of these coefficients on composition of particle does not allow using this method directly for age determination. Nevertheless SIMS is useful for dating of uranium materials, especially if the sample can contain small amounts of different materials. In this case the analysis of different fragments of materials by SIMS can confirm or not confirm the result, had been obtained by ICP-MS. If all detected and analyzed particles and fragments will have the same ratio of ion currents of Th230 and U234, the result of ICP-MS is true. If particles and fragments will have different ratios the result of ICP-MS cannot be related to any of presented materials. But in the last case the ages of different materials can be still estimated if different fragments have different ages, but the same elemental composition. The ''age'' had been determined by ICP-MS can be correlated with the average ratio of ion currents of Th230 and U234 had been determined by SIMS for all analyzed particles or fragments. This correlation determines the ratio of ionization coefficients of uranium and thorium, which should be the same for particles with the same elemental composition. (author)

Effect of artificial aging on the roughness and microhardness of sealed composites.

Science.gov (United States)

Catelan, Anderson; Briso, André L F; Sundfeld, Renato H; Dos Santos, Paulo H

2010-10-01

  The application of surface sealant could improve the surface quality and success of composite restorations; however, it is important to assess the behavior of this material when subjected to aging procedures.   To evaluate the effect of artificial aging on the surface roughness and microhardness of sealed microhybrids and nanofilled composites.   One hundred disc-shaped specimens were made for each composite. After 24 hours, all samples were polished and surface sealant was applied to 50 specimens of each composite. Surface roughness (Ra) was determined with a profilometer and Knoop microhardness was assessed with a 50-g load for 15 seconds. Ten specimens of each group were aged during 252 hours in a UV-accelerated aging chamber or immersed for 28 days in cola soft drink, orange juice, red wine staining solutions, or distilled water. Data were analyzed by two-way analysis of variance and Fischer's test (α=0.05).   Artificial aging decreased microhardness values for all materials, with the exceptions of Vit-l-escence (Ultradent Products Inc., South Jordan UT, USA) and Supreme XT (3M ESPE, St. Paul, MN, USA) sealed composites; surface roughness values were not altered. Water storage had less effect on microhardness, compared with the other aging processes. The sealed materials presented lower roughness and microhardness values, when compared with unsealed composites.   Aging methods decreased the microhardness values of a number of composites, with the exception of some sealed composites, but did not alter the surface roughness of the materials. The long-term maintenance of the surface quality of materials is fundamental to improving the longevity of esthetic restorations. In this manner, the use of surface sealants could be an important step in the restorative procedure using resin-based materials. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

A test of the 40Ar/39Ar age spectrum technique on some terrestrial materials

Science.gov (United States)

Lanphere, M.A.; Brent, Dalrymple G.

1971-01-01

40Ar/39Ar age spectra were determined for 10 terrestrial rock and mineral samples whose geologic history is known from independent evidence. The spectra for six mineral and whole rock samples, including biotite, feldspar, hornblende, muscovite, and granodiorite, that have experienced post-crystallization heating did not reveal the age of crystallization in any obvious way. Minima in the spectra, however, give reasonable maximum ages for reheating and high-temperature maxima can be interpreted as minimum crystallization ages. High-temperature ages of microcline and albite that have not been reheated are approximately 10% younger than the known crystallization age. Apparently there are no domains in these feldspars that have retained radiogenic 40Ar quantitatively. Spectra from two diabase samples that contain significant quantities of excess argon might mistakenly be interpreted as spectra from reheated samples and do not give the age of emplacement. The 40Ar/39Ar age spectrum technique may be a potentially valuable tool for the study of geologic areas with complex histories, but the interpretation of age spectra from terrestrial samples seems to be more difficult than suggested by some previous studies. ?? 1971.

Development of the structural materials information center

International Nuclear Information System (INIS)

Oland, C.B.; Naus, D.J.

1990-01-01

The U.S. Nuclear Regulatory Commission has initiated a Structural Aging Program at the Oak Ridge National Laboratory to identify potential structural safety issues related to continued service of nuclear power plants and to establish criteria for evaluating and resolving these issues. One of the tasks in this program focuses on the establishment of a Structural Materials Information Center where data and information on the time variation of concrete and other structural material properties under the influence of pertinent environmental stressors and aging factors are being collected and assembled into a database. This database will be used to assist in the prediction of potential long-term deterioration of critical structural components in nuclear power plants and to establish limits on hostile environmental exposure for these structures and materials. Two complementary database formats have been developed. The Structural Materials Handbook is an expandable, hard copy handbook that contains complete sets of data and information for selected portland cement concrete, metallic reinforcement, prestressing tendon, and structural steel materials. The Structural Materials Electronic Database is accessible by an IBM-compatible personal computer and provides an efficient means for searching the various database files to locate materials with similar properties. The database formats have been developed to accommodate data and information on the time-variation of concrete and other structural material properties. To date, the database includes information on concrete, reinforcement, prestressing, and structural steel materials

Acoustic emission: A useful tool for damage evaluation in composite materials

Science.gov (United States)

Mouzakis, Dionysios E.; Dimogianopoulos, Dimitrios G.

2018-02-01

High performance composites for aviation-related structures are prone to constant aging by environmental agents. Previous data from our work reported on the stiffening behaviour of glass fibre polyester composites used in the manufacturing of wind turbine blades. Airplanes from such composites are already on service nowadays. This justifies the detailed study of the exposure of high performance materials to environmental conditions such as varying temperature, humidity, ultraviolet radiation, in order to assess the impact of these important aging factors on their mechanical behaviour. The dramatic changes in the dynamic mechanical response of polymer matrix carbon fibre composites upon exposure to acceleration aging has been assessed in the present study. In order to assess the synergistic effect action of temperature and humidity on composites subjected to changes of temperature from -35 to +40 °C and humidity variations from behaviour of the aged materials. All tests were run both for aged and pristine materials for comparison purposes. Three point bending testing was performed in both static as well as in Dynamic mechanical analysis, for a range of temperatures and frequencies. Acoustic Emission damage detection was also performed during the three point bending test both in static and dynamic mode. The aged materials had gained in dynamic stiffness. In addition, that, the gain in the storage moduli, was accompanied by a decrease in the material damping ability, as determined by the tanδ parameter. In the final stages of the study, impact testing was performed on both pristine and aged specimens. The experimentally recorded force/time signals were utilized for concluding on the specimens' condition, by means of signal based damage detection methodologies. Effort was invested in utilizing signal analysis in order to get comparative aging-related information on the tested specimens in order to ultimately validate results of mechanical testing.

Modeling and analysis of aging behavior of concrete structures in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Rashid, J.Y.R.; James, R.J.; Dunham, R.S. [ANATECH (United States)

2011-07-01

As nuclear power plants approach the end of their original design life and begin to transition to the life extension phase, consideration has to be given to the effects of structural aging when evaluating the extended operation of reinforced or pre-stressed concrete structures. The behavior of concrete is highly nonlinear, having low tensile strength, shear stiffness and strength that depend on crack widths, and a confinement-dependent compressive elasto-plasticity. A concrete material model is described having the appropriate capabilities required for evaluating structural aging. The model treats reinforced concrete as a three-phase composite: plain concrete material as a three-dimensional continuum phase, steel reinforcement (rebar) as a uni-directional phase, and a rebar-concrete interaction phase. Structural aging is defined as the combined effects of time dependent material properties degradation and service induced changes in loading and operational conditions. Three broad categories of structural aging, and the interaction between them, are considered: 1) Aging effects due to expected time dependent changes in material properties, 2) Aging effects due to unexpected time dependent material degradation, and 3) Aging effects due to operational environment and loading. Example analyses are presented which illustrate the value of using advanced modeling and simulation in evaluating expected and unusual structural behavior. This is particularly important for safety structures that are approaching the end of their design life and are facing the prospect of re-licensing for extended operation

Hybrid sol-gel optical materials

Science.gov (United States)

Zeigler, John M.

1992-01-01

Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

Mechanical Properties and Corrosion Characteristics of Thermally Aged Alloy 22

International Nuclear Information System (INIS)

Rebak, R B; Crook, P

2002-01-01

Alloy 22 (UNS N06022) is a candidate material for the external wall of the high level nuclear waste containers for the potential repository site at Yucca Mountain. In the mill-annealed (MA) condition, Alloy 22 is a single face centered cubic phase. When exposed to temperatures on the order of 600 C and above for times higher than 1 h, this alloy may develop secondary phases that reduce its mechanical toughness and corrosion resistance. The objective of this work was to age Alloy 22 at temperatures between 482 C and 760 C for times between 0.25 h and 6,000 h and to study the mechanical and corrosion performance of the resulting material. Aging was carried out using wrought specimens as well as gas tungsten arc welded (GTAW) specimens. Mechanical and corrosion testing was carried out using ASTM standards. Results show-that the higher the aging temperature and the longer the aging time, the lower the impact toughness of the aged material and the lower its corrosion resistance. However, extrapolating both mechanical and corrosion laboratory data predicts that Alloy 22 will remain corrosion resistant and mechanically robust for the projected lifetime of the waste container

Computational materials design

International Nuclear Information System (INIS)

Snyder, R.L.

1999-01-01

Full text: Trial and error experimentation is an extremely expensive route to the development of new materials. The coming age of reduced defense funding will dramatically alter the way in which advanced materials have developed. In the absence of large funding we must concentrate on reducing the time and expense that the R and D of a new material consumes. This may be accomplished through the development of computational materials science. Materials are selected today by comparing the technical requirements to the materials databases. When existing materials cannot meet the requirements we explore new systems to develop a new material using experimental databases like the PDF. After proof of concept, the scaling of the new material to manufacture requires evaluating millions of parameter combinations to optimize the performance of the new device. Historically this process takes 10 to 20 years and requires hundreds of millions of dollars. The development of a focused set of computational tools to predict the final properties of new materials will permit the exploration of new materials systems with only a limited amount of materials characterization. However, to bound computational extrapolations, the experimental formulations and characterization will need to be tightly coupled to the computational tasks. The required experimental data must be obtained by dynamic, in-situ, very rapid characterization. Finally, to evaluate the optimization matrix required to manufacture the new material, very rapid in situ analysis techniques will be essential to intelligently monitor and optimize the formation of a desired microstructure. Techniques and examples for the rapid real-time application of XRPD and optical microscopy will be shown. Recent developments in the cross linking of the world's structural and diffraction databases will be presented as the basis for the future Total Pattern Analysis by XRPD. Copyright (1999) Australian X-ray Analytical Association Inc

Materials compatibility information data bank

International Nuclear Information System (INIS)

Mead, K.E.

1977-01-01

A major concern in the design of weapons systems is the compatibility of the materials used with each other and with the enclosed environment. Usually these systems require long term storage with a high reliability for proper function at the end of this storage period. Materials selection is then based on both past experience and laboratory accelerated aging experiments to assure this long term reliability. To assist in the task of materials selection a computerized materials compatibility data bank is being established. This data bank will provide a source of annotated information and references to personnel and documents for both the designer and materials engineer to draw on for guidance in materials selection. The data bank storage and information retrieval philosophy will be discussed and procedures for information gathering outlined. Examples of data entries and search routines will be presented to demonstrate the usefulness and versatility of the proposed system

Health monitoring method for composite materials

Science.gov (United States)

Watkins, Jr., Kenneth S.; Morris, Shelby J [Hampton, VA

2011-04-12

An in-situ method for monitoring the health of a composite component utilizes a condition sensor made of electrically conductive particles dispersed in a polymeric matrix. The sensor is bonded or otherwise formed on the matrix surface of the composite material. Age-related shrinkage of the sensor matrix results in a decrease in the resistivity of the condition sensor. Correlation of measured sensor resistivity with data from aged specimens allows indirect determination of mechanical damage and remaining age of the composite component.

Adhesive dental materials

International Nuclear Information System (INIS)

Unlu, N.

2005-01-01

Two main classes of material are involved, the glass-ionomer cements and the composite resins. This investigation describes the way they are bonded to the tooth and highlights their differences. Glass ionomers develop a zone of interaction with the tooth as they age which ultimately gives an extremely strong bond, and results in excellent retention rates. By contrast, bonding of composite resins is more complicated and possibly less effective, though these materials have better wear resistance and better aesthetics than glass ionomers. Assessment of bond durability is difficult. This is because a dental restorative can fail by a number of mechanisms apart from de bonding: for example, through wear or fracture

Societal Burden and Engineering Challenges of Ageing Infrastructure

NARCIS (Netherlands)

van Breugel, K.

2017-01-01

Ageing is an inherent feature of nature and, hence, of materials, structures and systems. Yet, it seems a rather new topic in both science and engineering. The main reason for increasing attention for ageing as a topic is the growing awareness that, particularly in industrialized countries,

Age-related macular degeneration in Onitsha, Nigeria | Nwosu ...

African Journals Online (AJOL)

Objectives: To determine the incidence, pattern and ocular morbidity associated with age-related macular degeneration (AMD) at the Guinness Eye Center Onitsha Nigeria. Materials and Methods: The case files of all new patients aged 50 years and above seen between January 1997 and December 2004 were reviewed.

Qualification of Electrical Components in Nuclear Power Plants. Management of Ageing

Energy Technology Data Exchange (ETDEWEB)

Spaang, Kjell [Ingemansson Technology AB, Goeteborg (Sweden); Staahl, Gunnar [Westinghouse Atom, Vaesteraas (Sweden)

2002-05-01

This report reviews R and D results and experiences forming the bases for the preparation of a report on management of ageing. It includes basic information and descriptions of value for persons who work with the questions and some data from investigations of the ageing characteristics of various materials: limit levels, dose-rate effects, activation energies, methods for condition monitoring, etc. This report is restricted to safety related components containing ageing sensitive parts, mainly organic materials (polymers). For components located in the containment, the possibilities of continuous supervision are limited. The accessibility for regular inspections is also limited in many cases. Therefore, the main part of this report deals with the qualification of such components. In addition, some material is given on qualification located outside containment with better possibilities for frequent inspection and supervision. A survey is made of activities, programs and tools for ageing qualification in connection with initial environmental qualification (type testing) as well as after installation (condition monitoring, extension of qualified life through on-going qualification). Tools are also given for supplementary ageing qualification of already installed components.

Qualification of Electrical Components in Nuclear Power Plants. Management of Ageing

International Nuclear Information System (INIS)

Spaang, Kjell; Staahl, Gunnar

2002-05-01

This report reviews R and D results and experiences forming the bases for the preparation of a report on management of ageing. It includes basic information and descriptions of value for persons who work with the questions and some data from investigations of the ageing characteristics of various materials: limit levels, dose-rate effects, activation energies, methods for condition monitoring, etc. This report is restricted to safety related components containing ageing sensitive parts, mainly organic materials (polymers). For components located in the containment, the possibilities of continuous supervision are limited. The accessibility for regular inspections is also limited in many cases. Therefore, the main part of this report deals with the qualification of such components. In addition, some material is given on qualification located outside containment with better possibilities for frequent inspection and supervision. A survey is made of activities, programs and tools for ageing qualification in connection with initial environmental qualification (type testing) as well as after installation (condition monitoring, extension of qualified life through on-going qualification). Tools are also given for supplementary ageing qualification of already installed components

Structural aging program status report

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.; Graves, H.L. III

1994-01-01

Research is being conducted at the Oak Ridge National Laboratory under Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of safety-related concrete structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Program accomplishments have included development of the Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, performance assessments of reinforced concrete structures in several United Kingdom nuclear power facilities, evaluation of European and North American repair practices for concrete, an evaluation of factors affecting the corrosion of metals embedded in concrete, and application of the time-dependent reliability methodology to reinforced concrete flexure and shear structural elements to investigate the role of in-service inspection and repair on their probability of failure

Nuclear power plant ageing and life extension: Safety aspects

International Nuclear Information System (INIS)

Novak, S.; Podest, M.

1987-01-01

Experience with large fossil-fired electrical generating units, as well as in all process industries, shows that plants begin to deteriorate with age after approximately 10 years of operation. Similar phenomena will prevail for nuclear plants, and it is reasonable to postulate that their availability will be affected, as will their safety, if appropriate measures are not taken. It is evident that the average age of power reactors in the IAEA's Member States is increasing. By 2000, more than 50 nuclear plants will have been providing electricity for 25 years or longer. Most nuclear power plants have operating lifetimes of between 20 and 40 years. Ageing is defined as a continuing time-dependent degradation of material due to service conditions, including normal operation and transient conditions. It is common experience that over long periods of time, there is a gradual change in the properties of materials. These changes can affect the capability of engineered components, systems, or structures to perform their required function. Not all changes are deleterious, but it is commonly observed that ageing processes normally involve a gradual reduction in performance capability. All materials in a nuclear power plant can suffer from ageing and can partially or totally lose their designed function. Ageing is not only of concern for active components (for which the probability of malfunction increases with time) but also for passive ones, since the safety margin is being reduced towards the lowest allowable level

EPRI research on component aging and nuclear plant life extension

International Nuclear Information System (INIS)

Sliter, G.E.; Carey, J.J.

1985-01-01

This paper first describes several research efforts sponsored by the Electric Power Research Institute (EPRI) that examine the aging degradation of organic materials and the nuclear plant equipment in which they appear. This research includes a compendium of material properties characterizing the effects of thermal and radiation aging, shake table testing to evaluate the effects of aging on the seismic performance of electrical components, and a review of condition monitoring techniques applicable to electrical equipment. Also described is a long-term investigation of natural versus artificial aging using reactor buildings as test beds. The paper then describes how the equipment aging research fits into a broad-scoped EPRI program on nuclear plant life extension. The objective of this program is to provide required information, technology, and guidelines to enable utilities to significantly extend operating life beyond the current 40-year licensed term

Modelling aging effects on a thermal cycling absorption process column

Energy Technology Data Exchange (ETDEWEB)

Laquerbe, C.; Contreras, S. [Commissariat a l' Energie Atomique - CEA/Valduc, F-21121 Is sur Tille (France); Baudouin, O. [ProSim SA, Stratege Bat. A, BP 27210, F-31672 Labege Cedex (France); Demoment, J. [Commissariat a l' Energie Atomique - CEA/Valduc, F-21121 Is sur Tille (France)

2008-07-15

Palladium coated on alumina is used in hydrogen separation systems operated at CEA/Valduc, and more particularly in Thermal Cycling Absorption Process columns. With such materials, tritium decay is known to induce aging effects which have direct side effects on hydrogen isotopes absorption isotherms. Furthermore in a TCAP column, aging occurs in an heterogeneous way. The possible impacts of these intrinsic material evolutions on the separation performances are investigated here through a numerical approach. (authors)

Readability of Written Materials for CKD Patients: A Systematic Review.

Science.gov (United States)

Morony, Suzanne; Flynn, Michaela; McCaffery, Kirsten J; Jansen, Jesse; Webster, Angela C

2015-06-01

The "average" patient has a literacy level of US grade 8 (age 13-14 years), but this may be lower for people with chronic kidney disease (CKD). Current guidelines suggest that patient education materials should be pitched at a literacy level of around 5th grade (age 10-11 years). This study aims to evaluate the readability of written materials targeted at patients with CKD. Systematic review. Patient information materials aimed at adults with CKD and written in English. Patient education materials designed to be printed and read, sourced from practices in Australia and online at all known websites run by relevant international CKD organizations during March 2014. Quantitative analysis of readability using Lexile Analyzer and Flesch-Kincaid tools. We analyzed 80 materials. Both Lexile Analyzer and Flesch-Kincaid analyses suggested that most materials required a minimum of grade 9 (age 14-15 years) schooling to read them. Only 5% of materials were pitched at the recommended level (grade 5). Readability formulas have inherent limitations and do not account for visual information. We did not consider other media through which patients with CKD may access information. Although the study covered materials from the United States, United Kingdom, and Australia, all non-Internet materials were sourced locally, and it is possible that some international paper-based materials were missed. Generalizability may be limited due to exclusion of non-English materials. These findings suggest that patient information materials aimed at patients with CKD are pitched above the average patient's literacy level. This issue is compounded by cognitive decline in patients with CKD, who may have lower literacy than the average patient. It suggests that information providers need to consider their audience more carefully when preparing patient information materials, including user testing with a low-literacy patient population. Copyright © 2015 National Kidney Foundation, Inc. Published by

Structural Materials: 95. Concrete

International Nuclear Information System (INIS)

Naus, Dan J.

2012-01-01

Nuclear power plant concrete structures and their materials of construction are described, and their operating experience noted. Aging and environmental factors that can affect the durability of the concrete structures are identified. Basic components of a program to manage aging of these structures are identified and described. Application of structural reliability theory to devise uniform risk-based criteria by which existing facilities can be evaluated to achieve a desired performance level when subjected to uncertain demands and to quantify the effects of degradation is outlined. Finally, several areas are identified where additional research is desired.

Report on aging of nuclear power plant reinforced concrete structures

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

1996-03-01

The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs

Report on aging of nuclear power plant reinforced concrete structures

Energy Technology Data Exchange (ETDEWEB)

Naus, D.J.; Oland, C.B. [Oak Ridge National Lab., TN (United States); Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

1996-03-01

The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

Divergent Trajectories in the Aging Mind: Changes in Working Memory for Affective Versus Visual Information With Age

OpenAIRE

Mikels, Joseph A.; Larkin, Gregory R.; Reuter-Lorenz, Patricia A.; Carstensen, Laura L.

2005-01-01

Working memory mediates the short-term maintenance of information. Virtually all empirical research on working memory involves investigations of working memory for verbal and visual information. Whereas aging is typically associated with a deficit in working memory for these types of information, recent findings suggestive of relatively well-preserved long-term memory for emotional information in older adults raise questions about working memory for emotional material. This study examined age...

Aging and the Picture Superiority Effect in Recall.

Science.gov (United States)

Winograd, Eugene; And Others

1982-01-01

Compared verbal and visual encoding using the picture superiority effect. One experiment found an interaction between age and type of material. In other experiments, the picture superiority effect was found in both age groups with no interaction. Performing a semantic-orienting task had no effect on recall. (Author/RC)

Age at menarche and pregnancy-related pelvic pain

DEFF Research Database (Denmark)

Kirkeby, Mette J; Biering, Karin; Olsen, Jørn

2013-01-01

AIM: Menarcheal age is a predictor of several complications related to pregnancy and diseases later in life. We aimed to study if menarcheal age is a risk factor for pregnancy-related pelvic pain. MATERIAL AND METHODS: A nested case-control study was conducted within the Danish National Birth...

Sandia Dynamic Materials Program Strategic Plan.

Energy Technology Data Exchange (ETDEWEB)

Flicker, Dawn Gustine [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Benage, John F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Desjarlais, Michael P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knudson, Marcus D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Leifeste, Gordon T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lemke, Raymond W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mattsson, Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wise, Jack L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-05-01

Materials in nuclear and conventional weapons can reach multi-megabar pressures and 1000s of degree temperatures on timescales ranging from microseconds to nanoseconds. Understanding the response of complex materials under these conditions is important for designing and assessing changes to nuclear weapons. In the next few decades, a major concern will be evaluating the behavior of aging materials and remanufactured components. The science to enable the program to underwrite decisions quickly and confidently on use, remanufacturing, and replacement of these materials will be critical to NNSA’s new Stockpile Responsiveness Program. Material response is also important for assessing the risks posed by adversaries or proliferants. Dynamic materials research, which refers to the use of high-speed experiments to produce extreme conditions in matter, is an important part of NNSA’s Stockpile Stewardship Program.

A Novel Approach to Detect Accelerated Aged and Surface-Mediated Degradation in Explosives by UPLC-ESI-MS.

Energy Technology Data Exchange (ETDEWEB)

Beppler, Christina L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-12-01

A new approach was created for studying energetic material degradation. This approach involved detecting and tentatively identifying non-volatile chemical species by liquid chromatography-mass spectrometry (LC-MS) with multivariate statistical data analysis that form as the CL-20 energetic material thermally degraded. Multivariate data analysis showed clear separation and clustering of samples based on sample group: either pristine or aged material. Further analysis showed counter-clockwise trends in the principal components analysis (PCA), a type of multivariate data analysis, Scores plots. These trends may indicate that there was a discrete shift in the chemical markers as the went from pristine to aged material, and then again when the aged CL-20 mixed with a potentially incompatible material was thermally aged for 4, 6, or 9 months. This new approach to studying energetic material degradation should provide greater knowledge of potential degradation markers in these materials.

Radiographic correlation of dental and skeletal age: Third molar, an age indicator.

Science.gov (United States)

Suma, Gn; Rao, Balaji B; Annigeri, Rajeshwari G; Rao, Dayashankara Jk; Goel, Sumit

2011-01-01

Age estimation plays a great role in forensic investigations, orthodontic and surgical treatment planning, and tooth transplantation. Teeth offer an excellent material for age determination by stages of development below the age of 25 years and by secondary changes after the age of 25 years. Third molar is often not included for this purpose due to its notorious developmental patterns. The aim of this study was to evaluate the development of third molar anlage in relation to skeletal maturities and the chronological age. One hundred and fifty-six young individuals, 78 males and 78 females, were selected. The stages of development of all the third molars in every individual were determined from panoramic radiographs. The skeletal development was assessed using hand wrist radiographs. Data were analyzed statistically for mean value, standard deviation and the relationship between the recorded characteristics. A STRONG CORRELATION WAS FOUND BETWEEN THIRD MOLAR DEVELOPMENT AND SKELETAL MATURITY (IN MALES: r=0.88, Pthird molar and 0.89 for mandibular third molar, Page, developmental stages of third molars and maturation of epiphyses of hand. Any of the three parameters could be used for the assessment of other maturities.

Effect of accelerated ageing and surface sealing on the permanent deformation of auto-polymerising soft linings.

Science.gov (United States)

da Silva, Joaquim; Takahashi, Jessica; Nuňez, Juliana; Consani, Rafael; Mesquita, Marcelo

2012-09-01

To compare the effects of different ageing methods on the permanent deformation of two permanent soft liners. The materials selected were auto-polymerising acrylic resin and silicone-based reliners. Sealer coating was also evaluated. Sixty specimens of each reliner were manufactured (12.7 mm diameter and 19 mm length). Specimens were randomly distributed into 12 groups (n = 10) and submitted to one of the accelerated ageing processes. Permanent deformation tests were conducted with a mechanical device described within the American Dental Association specification number 18 with a compressive load of 750 gf applied for 30 s. All data were submitted for statistical analysis. Mann-Whitney test compared the effect of the surface sealer on each material and the permanent deformation of the materials in the same ageing group (p = 0.05). Kruskal-Wallis and Dunn tests compared all ageing groups of each material (p = 0.05). The silicone-based reliner presented a lower permanent deformation than the acrylic resin-based reliner, regardless of the ageing procedure. The surface sealer coating was effective only for the thermocycled silicone group and the accelerated ageing processes affected only the permanent deformation of the acrylic resin-based material. The silicone-based reliner presented superior elastic properties and the thermocycling was more effective in ageing the materials. © 2010 The Gerodontology Society and John Wiley & Sons A/S.

Test of the wire ageing induced by radiation for the CMS barrel muon chamber

CERN Document Server

Conti, Enrico

2000-01-01

We have carried out laboratory test to measure the ageing of a wire tube due to pollutant outgassed by various materials. The tested materials are those used in the muon barrel drift tubes. An X-ray gun irradiated the test tube to accelerate the ageing process. No ageing effect has been measured for a period equivalent to 10 years of operation at LHC.

Advances in Integrated Computational Materials Engineering "ICME"

Science.gov (United States)

Hirsch, Jürgen

The methods of Integrated Computational Materials Engineering that were developed and successfully applied for Aluminium have been constantly improved. The main aspects and recent advances of integrated material and process modeling are simulations of material properties like strength and forming properties and for the specific microstructure evolution during processing (rolling, extrusion, annealing) under the influence of material constitution and process variations through the production process down to the final application. Examples are discussed for the through-process simulation of microstructures and related properties of Aluminium sheet, including DC ingot casting, pre-heating and homogenization, hot and cold rolling, final annealing. New results are included of simulation solution annealing and age hardening of 6xxx alloys for automotive applications. Physically based quantitative descriptions and computer assisted evaluation methods are new ICME methods of integrating new simulation tools also for customer applications, like heat affected zones in welding of age hardening alloys. The aspects of estimating the effect of specific elements due to growing recycling volumes requested also for high end Aluminium products are also discussed, being of special interest in the Aluminium producing industries.

The Utilization of Graphene Oxide in Traditional Construction Materials: Asphalt

Directory of Open Access Journals (Sweden)

Wenbo Zeng

2017-01-01

Full Text Available In the advanced research fields of solar cell and energy storing materials, graphene and graphene oxide (GO are two of the most promising materials due to their high specific surface area, and excellent electrical and physical properties. However, they was seldom studied in the traditional materials because of their high cost. Nowadays, graphene and GO are much cheaper than before with the development of production technologies, which provides the possibility of using these extraordinary materials in the traditional construction industry. In this paper, GO was selected as a nano-material to modify two different asphalts. Then a thin film oven test and a pressure aging vessel test were applied to simulate the aging of GO-modified asphalts. After thermal aging, basic physical properties (softening point and penetration were tested for the samples which were introduced at different mass ratios of GO (1% and 3% to asphalt. In addition, rheological properties were tested to investigate how GO could influence the asphalts by dynamic shearing rheometer tests. Finally, some interesting findings and potential utilization (warm mixing and flame retardants of GO in asphalt pavement construction were explained.

The Utilization of Graphene Oxide in Traditional Construction Materials: Asphalt.

Science.gov (United States)

Zeng, Wenbo; Wu, Shaopeng; Pang, Ling; Sun, Yihan; Chen, Zongwu

2017-01-07

In the advanced research fields of solar cell and energy storing materials, graphene and graphene oxide (GO) are two of the most promising materials due to their high specific surface area, and excellent electrical and physical properties. However, they was seldom studied in the traditional materials because of their high cost. Nowadays, graphene and GO are much cheaper than before with the development of production technologies, which provides the possibility of using these extraordinary materials in the traditional construction industry. In this paper, GO was selected as a nano-material to modify two different asphalts. Then a thin film oven test and a pressure aging vessel test were applied to simulate the aging of GO-modified asphalts. After thermal aging, basic physical properties (softening point and penetration) were tested for the samples which were introduced at different mass ratios of GO (1% and 3%) to asphalt. In addition, rheological properties were tested to investigate how GO could influence the asphalts by dynamic shearing rheometer tests. Finally, some interesting findings and potential utilization (warm mixing and flame retardants) of GO in asphalt pavement construction were explained.

Spirometry reference equations for central European populations from school age to old age.

Directory of Open Access Journals (Sweden)

Mascha K Rochat

Full Text Available BACKGROUND: Spirometry reference values are important for the interpretation of spirometry results. Reference values should be updated regularly, derived from a population as similar to the population for which they are to be used and span across all ages. Such spirometry reference equations are currently lacking for central European populations. OBJECTIVE: To develop spirometry reference equations for central European populations between 8 and 90 years of age. MATERIALS: We used data collected between January 1993 and December 2010 from a central European population. The data was modelled using "Generalized Additive Models for Location, Scale and Shape" (GAMLSS. RESULTS: The spirometry reference equations were derived from 118'891 individuals consisting of 60'624 (51% females and 58'267 (49% males. Altogether, there were 18'211 (15.3% children under the age of 18 years. CONCLUSION: We developed spirometry reference equations for a central European population between 8 and 90 years of age that can be implemented in a wide range of clinical settings.

Microstructures of cast-duplex stainless steel after long-term aging

International Nuclear Information System (INIS)

Chung, H.M.; Chopra, O.K.

1985-10-01

Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or during in-reactor service have been characterized and compared by TEM, SEM, and optical microscopy. The microstructural characteristics have been correlated with the impact failure behavior of the material. G-phase, α', and an unidentified Type X precipitate were responsible for the ferrite-phase embrittlement. Precipitation of M 23 C 6 carbides on austenite-ferrite boundaries further degraded the reactor-aged material

Microstructure, Corrosion and Magnetic Behavior of an Aged Dual-Phase Stainless Steel

Science.gov (United States)

Ziouche, A.; Haddad, A.; Badji, R.; Zergoug, M.; Zoubiri, N.; Bedjaoui, W.; Abaidia, S.

2018-03-01

In the present work, the effect of the precipitation phenomena on corrosion and magnetic behavior of an aged dual-phase stainless steel was investigated. Aging treatment caused the precipitation of the σ phase, chromium carbides and secondary austenite, which was accompanied by the shifting of the δ/γ interfaces inside the δ ferrite grains. Aging between 700 and 850 °C strongly deteriorated the pitting corrosion resistance of the studied material. Magnetic investigation of the aged material using the vibration sample magnetic technique revealed the sensitivity of the intrinsic magnetic properties to the smallest microstructural change. This was confirmed by the Eddy current technique that led also to the evaluation of the aging-induced localized corrosion.

Charasteristics of Ageing Population in Semarang City

Directory of Open Access Journals (Sweden)

Puji Hardati

2016-12-01

Full Text Available Increase of amount of ageing population represent the indication that a region have experienced of the ageing population. In some developing countries, of including Indonesia, growth of ageing population are estimate will mount quickly in period to come, although its percentage do not same. Whereas characteristic do not know surely. This matter is caused by there is view that ageing population of still not yet of this problem, but within long term will be are problem of if are not paid attention since now. Studying of ageing population of pursuant to its characteristic will assist in handling good problems now and also to come. With the existence of data of usable ageing population resident characteristic for the materials of population development planning in area.

Influence of fillers on mechanical properties of filled rubbers during ageing by irradiation

International Nuclear Information System (INIS)

Planes, Emilie

2008-01-01

The understanding of the evolution of mechanical properties and the prediction of the lifetime of material environment is a recurring problem. This question is very important to develop polymer formulations used for electrical cables in nuclear power plants. Thus it is important to know the evolution of materials when they are submitted to usual conditions in nuclear power plants. There are in literature some studies concerning the ageing by gamma irradiation of unfilled elastomer but the addition of fillers in the material can have consequences on the evolution of the mechanical properties during irradiation. Thus this work concerns the study of the ageing by gamma irradiation of filled rubbers and the identification of the role of fillers in the degradation mechanisms. The studied matrix, which commonly used for the type of application is EPDM. The fillers are: nano-scopic silica and aluminium trihydrate. Their surfaces have been treated in order to understand the role of filler-matrix interfaces during ageing. To evaluate the influence of fillers on the degradation mechanisms and on the evolution of the mechanical properties, the evolution during ageing of these materials filled or not has been studied for an ageing by irradiation: they have been physico-chemically, micro-structurally and mechanically characterized at various levels of ageing [fr

In situ LA-ICPMS U–Pb dating of cassiterite without a known-age matrix-matched reference material: Examples from worldwide tin deposits spanning the Proterozoic to the Tertiary

Science.gov (United States)

Neymark, Leonid; Holm-Denoma, Christopher S.; Moscati, Richard J.

2018-01-01

Cassiterite (SnO2), a main ore mineral in tin deposits, is suitable for U–Pb isotopic dating because of its relatively high U/Pb ratios and typically low common Pb. We report a LA-ICPMS analytical procedure for U–Pb dating of this mineral with no need for an independently dated matrix-matched cassiterite standard. LA-ICPMS U-Th-Pb data were acquired while using NIST 612 glass as a primary non-matrix-matched standard. Raw data are reduced using a combination of Iolite™ and other off-line data reduction methods. Cassiterite is extremely difficult to digest, so traditional approaches in LA-ICPMS U-Pb geochronology that utilize well-characterized matrix-matched reference materials (e.g., age values determined by ID-TIMS) cannot be easily implemented. We propose a new approach for in situ LA-ICPMS dating of cassiterite, which benefits from the unique chemistry of cassiterite with extremely low Th concentrations (Th/U ratio of 10−4 or lower) in some cassiterite samples. Accordingly, it is assumed that 208Pb measured in cassiterite is mostly of non-radiogenic origin—it was initially incorporated in cassiterite during mineral formation, and can be used as a proxy for common Pb. Using 208Pb as a common Pb proxy instead of 204Pb is preferred as 204Pb is much less abundant and is also compromised by 204Hg interference during the LA-ICPMS analyses.Our procedure relies on 208Pb/206Pb vs 207Pb/206Pb (Pb-Pb) and Tera-Wasserburg 207Pb/206Pb vs 238U/206Pb (U-Pb) isochron dates that are calculated for a ~1.54 Ga low-Th cassiterite reference material with varying amounts of common Pb that we assume remained a closed U-Pb system. The difference between the NIST 612 glass normalized biased U-Pb date and the Pb-Pb age of the reference material is used to calculate a correction factor (F) for instrumental U-Pb fractionation. The correction factor (F) is then applied to measured U/Pb ratios and Tera-Wasserburg isochron dates are obtained for the unknown

[Ageing and work: technical standards].

Science.gov (United States)

De Vito, G; Riva, M A; Meroni, R; Cesana, G C

2010-01-01

Over the last few years, studies on the relationship between ageing and work have attracted growing interest due to the increased probability among workers of developing major health problems as a consequence of ageing of the working population. Negative outcomes for health are possible when an age-related imbalance appears between physical workload and physical work capacity. Interventions based on workload reductions should help to keep workers on the job for as long as allowed by law. Reference masses by age and sex are suggested by the technical standards of the ISO 11228 series, which are also quoted by Italian law D.Lgs. 81/2008, and EN 1005 series, which recommend limits valid also for manual material handling, and pushing and pulling. Decreasing low back pain prevalence or recurrence, in an ageing population with high prevalence of back disorders, could be more effective than many other approaches to enhance workers' quality of life and consequently maintain and improve workers' performance.

Material Modelling - Composite Approach

DEFF Research Database (Denmark)

Nielsen, Lauge Fuglsang

1997-01-01

is successfully justified comparing predicted results with experimental data obtained in the HETEK-project on creep, relaxation, and shrinkage of very young concretes cured at a temperature of T = 20^o C and a relative humidity of RH = 100%. The model is also justified comparing predicted creep, shrinkage......, and internal stresses caused by drying shrinkage with experimental results reported in the literature on the mechanical behavior of mature concretes. It is then concluded that the model presented applied in general with respect to age at loading.From a stress analysis point of view the most important finding...... in this report is that cement paste and concrete behave practically as linear-viscoelastic materials from an age of approximately 10 hours. This is a significant age extension relative to earlier studies in the literature where linear-viscoelastic behavior is only demonstrated from ages of a few days. Thus...

Effect of ageing on tensile behavior of ultrafine grained Al 6061 alloy

Energy Technology Data Exchange (ETDEWEB)

Rao, P. Nageswara [Department of Metallurgical and Materials Engineering & Centre of Nanotechnology, IIT Roorkee, Roorkee 247667 (India); Singh, Dharmendra [Department of Mechanical Engineering, Government Engineering College, Bikaner 304001 (India); Brokmeier, Heinz-Günter [Helmholtz Zentrum Geesthacht, Max Planck Straße 1, Geb 33, D-21502 Geesthacht (Germany); Jayaganthan, R., E-mail: rjayafmt@iitr.ernet.in [Department of Metallurgical and Materials Engineering & Centre of Nanotechnology, IIT Roorkee, Roorkee 247667 (India)

2015-08-12

In the present investigation, the ageing behavior of ultrafine grained (UFG) Al 6061 alloy, processed through multi-directional forging (MDF) at cryogenic temperature was investigated. The evolution of microstructure was investigated through transmission electron microscopy and electron back scattered diffraction technique. The results indicate that homogeneous microstructure with an ultrafine grain morphology (average size 250 nm) was achieved through cryogenic forging of the alloy subjected to prior solutionising treatment. Tensile testing at room temperature revealed that MDFed material after ageing led to significant improvement in work hardening and its tensile ductility. Strengthening of the matrix through various mechanisms has been quantified with the existing models to estimate the yield strength of the as forged and peak aged material. The precipitation hardening response in UFG material is found to be 35% lower than that of the coarse grained material as observed in the present work.

Adult Materialism/Postmaterialism and Later Mental Health: The Role of Self-Efficacy

Science.gov (United States)

Flouri, Eirini

2005-01-01

This study used data from the British National Child Development Study (NCDS) to examine the relationship between materialism/postmaterialism and later mental health. Materialism/postmaterialism was assessed (using Inglehart's 4-item index) at age 33 and mental health (measured by the GHQ-12) was assessed at age 42. It was found that after…

Instrumental evaluation of anti-aging effects of cosmetic formulations containing palmitoyl peptides, Silybum marianum seed oil, vitamin E and other functional ingredients on aged human skin.

Science.gov (United States)

Hahn, Hyung Jin; Jung, Ho Jung; Schrammek-Drusios, Med Christine; Lee, Sung Nae; Kim, Ji-Hyun; Kwon, Seung Bin; An, In-Sook; An, Sungkwan; Ahn, Kyu Joong

2016-08-01

Anti-aging cosmetics are widely used for improving signs of aged skin such as skin wrinkles, decreased elasticity, low dermal density and yellow skin tone. The present study evaluated the effects of cosmetic formulations, eye cream and facial cream, containing palmitoyl peptides, Silybum marianum ( S. marianum ) seed oil, vitamin E and other functional ingredients on the improvement of facial wrinkles, elasticity, dermal density and skin tone after 4 weeks period of application on aged human skin. Healthy volunteers (n=20) with aged skin were recruited to apply the test materials facially twice per day for 4 weeks. Skin wrinkles, elasticity, dermal density and skin tone were measured instrumentally for assessing the improvement of skin aging. All the measurements were conducted prior to the application of test materials and at 2 and 4 weeks of treatment. Crow's feet wrinkles were decreased 5.97% after 2 weeks of test material application and 14.07% after 4 weeks of application in comparison of pre-application. Skin elasticity was increased 6.81% after 2 weeks and 8.79% after 4 weeks. Dermal density was increased 16.74% after 2 weeks and 27.63% after 4 weeks. With the L* value indicating skin brightness and the a* value indicating erythema (redness), the results showed that brightness was increased 1.70% after 2 weeks and 2.14% after 4 weeks, and erythema was decreased 10.45% after 2 weeks and 22.39% after 4 weeks. Hence, the test materials appear to exert some degree of anti-aging effects on aged human skin. There were no abnormal skin responses from the participants during the trial period. We conclude that the facial and eye cream containing palmitoyl peptides and S. marianum seed oil, vitamin E and other ingredients have effects on the improvement of facial wrinkles, elasticity, dermal density and skin tone.

Aging of concrete structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Pland, C.B.; Arndt, E.G.

1991-01-01

The Structural Aging (SAG) Program, sponsored by the US Nuclear Regulatory Commission (USNRC) and conducted by the Oak Ridge National Laboratory (ORNL), had the overall objective of providing the USNRC with an improved basis for evaluating nuclear power plant structures for continued service. The program consists of three technical tasks: materials property data base, structural component assessment/repair technology, and quantitative methodology for continued service determinations. Major accomplishments under the SAG Program during the first two years of its planned five-year duration have included: development of a Structural Materials Information Center and formulation of a Structural Aging Assessment Methodology for Concrete Structures in Nuclear Power Plants. 9 refs

2004 research briefs :Materials and Process Sciences Center.

Energy Technology Data Exchange (ETDEWEB)

Cieslak, Michael J.

2004-01-01

This report is the latest in a continuing series that highlights the recent technical accomplishments associated with the work being performed within the Materials and Process Sciences Center. Our research and development activities primarily address the materials-engineering needs of Sandia's Nuclear-Weapons (NW) program. In addition, we have significant efforts that support programs managed by the other laboratory business units. Our wide range of activities occurs within six thematic areas: Materials Aging and Reliability, Scientifically Engineered Materials, Materials Processing, Materials Characterization, Materials for Microsystems, and Materials Modeling and Simulation. We believe these highlights collectively demonstrate the importance that a strong materials-science base has on the ultimate success of the NW program and the overall DOE technology portfolio.

Helium embrittlement model and program plan for weldability of ITER materials

International Nuclear Information System (INIS)

Louthan, M.R. Jr.; Kanne, W.R. Jr.; Tosten, M.H.; Rankin, D.T.; Cross, B.J.

1997-02-01

This report presents a refined model of how helium embrittles irradiated stainless steel during welding. The model was developed based on experimental observations drawn from experience at the Savannah River Site and from an extensive literature search. The model shows how helium content, stress, and temperature interact to produce embrittlement. The model takes into account defect structure, time, and gradients in stress, temperature and composition. The report also proposes an experimental program based on the refined helium embrittlement model. A parametric study of the effect of initial defect density on the resulting helium bubble distribution and weldability of tritium aged material is proposed to demonstrate the roll that defects play in embrittlement. This study should include samples charged using vastly different aging times to obtain equivalent helium contents. Additionally, studies to establish the minimal sample thickness and size are needed for extrapolation to real structural materials. The results of these studies should provide a technical basis for the use of tritium aged materials to predict the weldability of irradiated structures. Use of tritium charged and aged material would provide a cost effective approach to developing weld repair techniques for ITER components

Assessing environmental effects on organic materials in cultural heritage

DEFF Research Database (Denmark)

Boyatzis, Stamatis; Ioakimoglou, Eleni; Facorellis, Yorgos

2015-01-01

Under the auspices of INVENVORG (Thales Research Funding Program – NRSF), and within a holistic approach for assessing environmental effects on organic materials in cultural heritage (CH) artefacts, the effect of artificial ageing on elemental and molecular damage and their effects...... on the structural integrity of bone was investigated. Metapodial roe deer bone samples were artificially aged under humidity and atmospheres of sulfur and nitrogen oxides in room temperature. Elemental micro-analysis of bone material through SEM-EDX and molecular investigations through FTIR and Raman spectroscopy...

Bar code usage in nuclear materials accountability

International Nuclear Information System (INIS)

Mee, W.T.

1983-01-01

The age old method of physically taking an inventory of materials by listing each item's identification number has lived beyond its usefulness. In this age of computerization, which offers the local grocery store a quick, sure, and easy means to inventory, it is time for nuclear materials facilities to automate accountability activities. The Oak Ridge Y-12 Plant began investigating the use of automated data collection devices in 1979. At that time, bar code and optical-character-recognition (OCR) systems were reviewed with the purpose of directly entering data into DYMCAS (Dynamic Special Nuclear Materials Control and Accountability System). Both of these systems appeared applicable; however, other automated devices already employed for production control made implementing the bar code and OCR seem improbable. However, the DYMCAS was placed on line for nuclear material accountability, a decision was made to consider the bar code for physical inventory listings. For the past several months a development program has been underway to use a bar code device to collect and input data to the DYMCAS on the uranium recovery operations. Programs have been completed and tested, and are being employed to ensure that data will be compatible and useful. Bar code implementation and expansion of its use for all nuclear material inventory activity in Y-12 is presented

The development and characterization of stimuli-responsive systems for performance materials

Science.gov (United States)

Gordon, Melissa B.

In nature, living organisms adjust to their surroundings by responding to environmental cues, such as light, temperature or force. Stimuli-triggered processes, such as the contraction of eyes in response to bright light or wound healing in skin after a cut, motivate the design of "smart" materials which are designed to respond to environmental stimuli. Responsive materials are used as self-healing materials, shape memory polymers and responsive coatings; moreover, responsive materials may also be employed as model systems, which enhance understanding of complex behavior. The overall goal of this work is to design a material that offers self-healing functionality, which will allow for self-repair following material fatigue or failure, and increased strength in response to ballistic or puncture threats through the incorporation of colloidal particles. The target application for this material is as a protective barrier in extreme environments, such as outer space. Towards this end, the dissertation is focused on the development and characterization of each component of the protective material by (1) designing and testing novel light- and force-sensitive polymers for self-healing applications and (2) examining and characterizing long-time behavior (i.e., aging) in model thermoreversible colloidal gels and glasses. Towards the development of novel stimuli-responsive materials, a photo-responsive polymer network is developed in which a dynamic bond is incorporated into the network architecture to enable a light-triggered, secondary polymerization, which increases the modulus by two orders of magnitude while strengthening the network by over 100%. Unlike traditional two-stage polymerization systems, in which the secondary polymerization is triggered by a leachable photoinitiator, the dynamic nature is imparted by the material itself via the dissociation of its own crosslinks to become stronger in response to light. Several attributes of the photo-responsive network are

Lifetime estimation of zirconia ceramics by linear ageing kinetics

International Nuclear Information System (INIS)

Zhang, Fei; Inokoshi, Masanao; Vanmeensel, Kim; Van Meerbeek, Bart; Naert, Ignace; Vleugels, Jef

2015-01-01

Up to now, the ageing kinetics of zirconia ceramics were mainly derived from the sigmoidal evolution of the surface phase transformation as a function of time, as quantified by means of X-ray diffraction (XRD). However, the transformation propagation into the material should be better to monitor the ageing kinetics. In this work, μ-Raman spectroscopy was used to quantitatively measure the transformation profiles in depth as a function of ageing time at 160 °C, 140 °C, 134 °C and 110 °C. A linear relationship between the transformed depth and the ageing time was observed for all investigated yttria stabilized tetragonal zirconia polycrystals (3Y-TZP). Furthermore, the μ-Raman investigation of residual stresses in the subsurface of aged 3Y-TZPs showed that the highest tensile stress was located just ahead of the transformation front, indicating the key responsibility of stress accumulation for transformation front propagating into the material. Moreover, the linear kinetics of the transformation propagation were more accurate to calculate the apparent activation energy of the ageing process and allowed a more straightforward estimation of the lifetime of 3Y-TZP at body temperature, as compared to the conventional ageing kinetic parameters obtained from the surface transformation analysis by XRD

Ageing of insulation and diagnosis of electrical equipment through detection of partial discharge

International Nuclear Information System (INIS)

Lopez Vergara, T.; Velasco Bernal, C.

1994-01-01

Ageing in electrical equipment affects mainly its insulation system. Such ageing in the insulation system is determined by its organic nature, basically constituted by three families of materials: cellulose, resin and hydrocarbon. All of these are affected by high temperatures, which tend to produce a break in the molecular chains (if the temperatures are not too high) or carbonization and gasification of the material (if they are). The radiation absorbed by the insulating materials also destroys molecular chains, causing degradation of the material. The break of the molecular chains, especially in the polymer-based materials, fragments the material, mainly in areas subjected to mechanical forces and stresses. From the electrical point of view, fissures occurring the insulating material lead to a much lower dielectric strength in certain parts of the materials, which could produce partial discharge conditions. Therefore, the growth of partial discharges in electrical equipment items is frequently the consequences of ageing, and be used to evaluate their residual life. Empresarios Agrupados has developed a system to detect partial discharges which can be used while equipment is still in operation. The measurements taken with this system are sufficiently accurate and repetitive to be used in evaluating the condition of medium-voltage electrical equipment insulation. (Author)

Method for accelerated aging under combined environmental stress conditions

International Nuclear Information System (INIS)

Gillen, K.T.

1979-01-01

An accelerated aging method which can be used to simulate aging in combined stress environment situations is described. It is shown how the assumptions of the method can be tested experimentally. Aging data for a chloroprene cable jacketing material in single and combined radiation and temperature environments are analyzed and it is shown that these data offer evidence for the validity of the method

Ageing and life prediction of cast duplex stainless steel components

International Nuclear Information System (INIS)

Chung, H.M.

1992-01-01

Cast duplex stainless steels, used extensively in nuclear, chemical and petroleum industries because of higher strength, better weldability, higher resistance to stress corrosion cracking, and soundness of casting, are susceptible to thermal aging embrittlement during service at temperatures as low as ∼250 o C. Recent advances in understanding the aging mechanisms, kinetics, and mechanical properties are presented, with emphasis on application of the material in safety-significant components in a nuclear reactor. Aging embrittlement is primarily due to spinodal decomposition of ferrite involving segregation of Fe, Cr, and Ni, and precipitation of M 23 C 6 on ferrite-austenite boundaries or in ferrite. Aging kinetics are strongly influenced by synergistic effects of other metallurgical reactions that occur in parallel with the spinodal decomposition, i.e. clustering of Ni, Mo, and Si and G-phase precipitation in ferrite. A number of methods are outlined for estimating end-of-life aging, depending on several factors such as degree of permissible conservatism, availability of component archive material, and methods of estimating and verifying the activation energy of aging. (Author)

Aging degradation of cast stainless steel: status and program

Energy Technology Data Exchange (ETDEWEB)

Chopra, O.K.; Ayrault, G.

1983-10-01

A program has been initiated to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. The existing data are reviewed to determine the critical parameters that control the aging behavior and to define the objectives and scope of the investigation. The test matrices for microstructural studies and mechanical property measurements are presented. The initial experimental effort is focussed on characterizing the microstructure of long-term, low-temperature aged material. Specimens from three heats of cast CF-8 and CF-8M stainless steel aged for up to 70,000 h at 300, 350, and 400/sup 0/C were obtained from George Fisher Ltd., of Switzerland. Initial analyses reveal the formation of three different types of precipitates which are not ..cap alpha..'. An FCC phase, similar to the M/sub 23/C/sub 6/ precipitates, was present in all the long-term aged material. 15 references, 10 figures, 2 tables.

Aging degradation of cast stainless steel: status and program

International Nuclear Information System (INIS)

Chopra, O.K.; Ayrault, G.

1983-10-01

A program has been initiated to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. The existing data are reviewed to determine the critical parameters that control the aging behavior and to define the objectives and scope of the investigation. The test matrices for microstructural studies and mechanical property measurements are presented. The initial experimental effort is focussed on characterizing the microstructure of long-term, low-temperature aged material. Specimens from three heats of cast CF-8 and CF-8M stainless steel aged for up to 70,000 h at 300, 350, and 400 0 C were obtained from George Fisher Ltd., of Switzerland. Initial analyses reveal the formation of three different types of precipitates which are not α'. An FCC phase, similar to the M 23 C 6 precipitates, was present in all the long-term aged material. 15 references, 10 figures, 2 tables

Ageing of instrumentation and control cables in NPPs

International Nuclear Information System (INIS)

Santhosh; Ghosh, A.K.; Fernandes, B.G.

2011-01-01

Cables are vital components of instrumentation and control (I and C) systems in nuclear power plants (NPPs). The polymer materials used for insulation and jacket materials for electric cables are susceptible to ageing and degradation mechanisms caused by exposure to many of the stressors encountered in NPP service conditions. Ageing of components in NPP is an important concern since the degradation caused by ageing can impact the performance of susceptible equipment. This is of particular concern for safety-related equipment since the failure due to ageing can compromise the continued safe operation of the plant. The state-of-the art for incorporating cable ageing effects into probabilistic safety assessment (PSA) is still evolving and in the reliability assessment of NPP systems, the ageing effect of electrical cable is generally not considered and also, there is no standard method exists for incorporating such ageing effects into the system reliability. Therefore, identification and quantification of ageing of electrical cables is very much essential for an accurate prediction of system reliability for PSA applications. The objective of this study is to develop a methodology to assess the susceptibility of polymeric cable insulation to various ageing mechanisms; and the state of the insulation at any chosen time in order to evaluate the remaining life-time of operating cables in NPPs. This paper presents the state-of-the-art tools and techniques for insulation condition assessment, insulation life prediction methodologies, equipment qualification guidelines, and ageing management programs relating to I and C cables in NPPs. An approach to calculate the insulation resistance subjecting to different stressors has also been presented in this paper. (author)

Test of the wire ageing induced by radiation for the CMS barrel muon chambers

CERN Document Server

Conti, E

2001-01-01

We have carried out laboratory tests to measure the ageing of a wire tube due to pollutants outgassed by various materials. The tested materials are those used in the barrel muon drift tubes of the CMS experiment at LHC. An X-ray gun irradiated the test tube to accelerate the ageing process. No ageing effect has been measured for a period equivalent to 10 years of operation at LHC. (15 refs).

Accelerated materials evaluation for nuclear applications

Energy Technology Data Exchange (ETDEWEB)

Griffiths, M., E-mail: malcolm.griffiths@queensu.ca [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, Ontario, K7L 3N6 (Canada); Walters, L. [Canadian Nuclear Laboratories, Chalk River, ON, K0J 1J0 (Canada); Greenwood, L.R. [Pacific Northwest National Laboratory, Richland, WA, 99352 (United States); Garner, F.A. [Radiation Effects Consulting, Richland, WA, 99352 (United States)

2017-05-15

This paper addresses the opportunities and complexities of using materials test reactors with high neutron fluxes to perform accelerated studies of material aging in power reactors operating at lower neutron fluxes and with different neutron flux spectra. Radiation damage and gas production in different reactors have been compared using the code, SPECTER. This code provides a common standard from which to compare neutron damage data generated by different research groups using a variety of reactors.

Ageing of significant to safety structure elements of nuclear power plants

International Nuclear Information System (INIS)

Maksimovas, G.; Ramanauskiene, A.; Ziliukas, A.

1999-01-01

The paper analyzes the ageing problems of structure elements in nuclear power plants. The standard documents and principal parts of the ageing evaluation program are presented. The ageing evaluation model is being worked out and degradation mechanisms of different atomic reactor materials are being compared. (author)

Study of Aging-Induced Degradation of Fracture Resistance of Alloy 617 Toward High-Temperature Applications

Science.gov (United States)

Singh, Aditya Narayan; Moitra, A.; Bhaskar, Pragna; Sasikala, G.; Dasgupta, Arup; Bhaduri, A. K.

2017-07-01

For the Alloy 617, the effect of aging on the fracture energy degradation has been investigated after aging for different time periods at 1023 K (750 °C). A sharp reduction in impact energy (by 55 pct vis-à-vis the as-received material) after 1000 hours of aging, as evaluated from room-temperature Charpy impact tests, has been observed. Further aging up to 10,000 hours has led to a degradation of fracture energy up to 78 pct. Fractographic examinations using scanning electron microscopy (SEM) have revealed a change in fracture mode from fibrous-ductile for the un-aged material to intergranular mode for the aged one. The extent of intergranular fracture increases with the increasing aging time, indicating a tendency of the material to undergo grain boundary embrittlement over long-term aging. Analysis of the transmission electron microscopy (TEM) micrographs along with selected area diffraction (SAD) patterns for the samples aged at 10,000 hours revealed finely dispersed γ' precipitates of size 30 to 40 nm, rich in Al and Ti, along with extensive precipitation of M23C6 at the grain boundaries. In addition, the presence of Ni3Si of size in the range of 110 to 120 nm also has been noticed. The extensive precipitation of M23C6 at the grain boundaries have been considered as a major reason for aging-induced embrittlement of this material.

Auto-regenerative TL dating with zircon inclusions from fired materials

International Nuclear Information System (INIS)

Templer, R.H.; Smith, B.W.

1988-01-01

In this paper it is shown that it is possible to date fired material using zircon inclusions. The effects of zoning and anomalous fading are overcome using an auto-regenerative dating procedure. The high radioactivity of the grains gives a measurable self-induced TL (thermoluminescence) signal within a few months. Comparison of this ''auto-regenerated'' TL with the natural TL (which has accumulated since the firing) yields the age of the material. A sensitive TL reader capable of recording the auto-regenerated signal after 6 months is also described, and the results of age determinations on a number of known age samples are presented. (author)

Ageing of structural materials in tokamaks: TEXTOR liner study

Science.gov (United States)

Weckmann, A.; Petersson, P.; Rubel, M.; Fortuna-Zaleśna, E.; Zielinski, W.; Romelczyk-Baishya, B.; Grigore, E.; Ruset, C.; Kreter, A.

2017-12-01

After the final shut-down of the tokamak TEXTOR, all of its machine parts became accessible for comprehensive studies. This unique opportunity enabled the study of the Inconel 625 liner by a wide range of methods. The aim was to evaluate eventual alteration of surface and bulk characteristics from recessed wall elements that may influence the machine performance. The surface was covered with stratified layers consisting mainly of boron, carbon, oxygen, and in some cases also silicon. Wall conditioning and limiter materials hence predominantly define deposition on the liner. Deposited layers on recessed wall elements reach micrometre thickness within decades, peel off and may contribute to the dust inventory in tokamaks. Deuterium content was about 4,7 at% on average most probably due to wall conditioning with deuterated gas, and very low concentration in the Inconel substrate. Inconel 625 retained its mechanical strength despite 26 years of cyclic heating, stresses and particle bombardment.

Tritium Storage Material

International Nuclear Information System (INIS)

Cowgill, Donald F.; Luo, Weifang; Smugeresky, John E.; Robinson, David B.; Fares, Stephen James; Ong, Markus D.; Arslan, Ilke; Tran, Kim L.; McCarty, Kevin F.; Sartor, George B.; Stewart, Kenneth D.; Clift, W. Miles

2008-01-01

Nano-structured palladium is examined as a tritium storage material with the potential to release beta-decay-generated helium at the generation rate, thereby mitigating the aging effects produced by enlarging He bubbles. Helium retention in proposed structures is modeled by adapting the Sandia Bubble Evolution model to nano-dimensional material. The model shows that even with ligament dimensions of 6-12 nm, elevated temperatures will be required for low He retention. Two nanomaterial synthesis pathways were explored: de-alloying and surfactant templating. For de-alloying, PdAg alloys with piranha etchants appeared likely to generate the desired morphology with some additional development effort. Nano-structured 50 nm Pd particles with 2-3 nm pores were successfully produced by surfactant templating using PdCl salts and an oligo(ethylene oxide) hexadecyl ether surfactant. Tests were performed on this material to investigate processes for removing residual pore fluids and to examine the thermal stability of pores. A tritium manifold was fabricated to measure the early He release behavior of this and Pd black material and is installed in the Tritium Science Station glove box at LLNL. Pressure-composition isotherms and particle sizes of a commercial Pd black were measured.

Summary Report of Cable Aging and Performance Data for Fiscal Year 2014.

Energy Technology Data Exchange (ETDEWEB)

Celina, Mathias C.; Celina, Mathias C.; Redline, Erica Marie; Redline, Erica Marie; Bernstein, Robert; Bernstein, Robert; Quintana, Adam; Quintana, Adam; Giron, Nicholas Henry; Giron, Nicholas Henry; White II, Gregory Von; White II, Gregory Von

2014-09-01

As part of the Light Water Reactor Sustainability Program, science - based engineering approaches were employed to address cable degradation behavior under a range of exposure environments. Experiments were conducted with the goal to provide best guidance for aged material states, remaining life and expected performance under specific conditions for a range of cable materials. Generic engineering tests , which focus on rapid accelerated aging and tensile elongation , were combined with complementar y methods from polymer degradation science. Sandia's approach, building on previous years' efforts, enabled the generation of some of the necessary data supporting the development of improved lifetime predictions models, which incorporate known material b ehaviors and feedback from field - returned 'aged' cable materials. Oxidation rate measurements have provided access to material behavior under low dose rate thermal conditions, where slow degradation is not apparent in mechanical property changes. Such da ta have shown aging kinetics consistent with established radiati on - thermal degradation models. ACKNOWLEDGEMENTS We gratefully acknowledge ongoing technical support at the LICA facility and extensive sample handling provided by Maryla Wasiolek and Don Hans on. Sam Durbin and Patrick Mattie are recognized for valuable guidance throughout the year and assistance in the preparation of the final report. Doug Brunson is appreciated for sample analysis, compilation and plotting of experimental data.

Human factors: A major issue in plant aging

International Nuclear Information System (INIS)

Widrig, R.D.

1985-01-01

Humans play a significant role in the effects of aging on safe and reliable operation of nuclear power plants. These human issues may be more important than the issues of materials and component degradation with age. Human actions can accelerate or decelerate physical aging of a plant. And an aging plant can have a significant negative impact on staff quality and performance. The purpose of this paper is to provide some insights into the nature of these human factors issues and their relationship to plant aging. An early awareness of these issues facilitates timely action to at least mitigate these problems before they become insurmountable

Accelerated Aging Experiments for Prognostics of Damage Growth in Composite Materials

Science.gov (United States)

2011-09-01

builds on current understanding of fault modes in composites. This paper investigates faults in laminated ply composites. Such structures mainly...experiments where intermittent ground truth and in-situ characteristics are collected. Growth patterns are analyzed for damage types typical of laminated ...2: [0/902/45/-45/90], and Layup 3: [902/45/-45]2. Torayca T700G uni-directional carbon- prepreg material was used for 15.24 cm x 25.4 cm coupons with

Magnetic ageing study of high and medium permeability nanocrystalline FeSiCuNbB alloys

Energy Technology Data Exchange (ETDEWEB)

Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

2017-04-15

increasing the energy efficiency is one of the most important issues in modern power electronic systems. In aircraft applications, the energy efficiency must be associated with a maximum reduction of mass and volume, so a high components compactness. A consequence from this compactness is the increase of operating temperature. Thus, the magnetic materials used in these applications, have to work at high temperature. It raises the question of the thermal ageing problem. The reliability of these components operating at this condition becomes a real problem which deserves serious interest. Our work takes part in this context by studying the magnetic material thermal ageing. The nanocrystalline materials are getting more and more used in power electronic applications. Main advantages of nanocrystalline materials compared to ferrite are: high saturation flux density of almost 1.25 T and low dynamic losses for low and medium frequencies. The nanocrystalline Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloys have been chosen in our aging study. This study is based on monitoring the magnetic characteristics for several continuous thermal ageing (100, 150, 200 and 240 °C). An important experimental work of magnetic characterization is being done following a specific monitoring protocol. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The magnetic ageing of the nanocrystalline materials is related to their annealing. • The degradations with ageing are not related to a change of the grain size diameter. • The amount of anisotropies introduced with ageing depends just on ageing conditions.

Methods for determination of the age of Pleistocene tephra, derived ...

Indian Academy of Sciences (India)

five of our samples has yielded material with an apparent age similar to that expected for eruption D. These numerical ages, of ..... about the history of uptake of radioactive elements ...... Approach to Management of Water and Soil of the Purna.

Development of the Structural Materials Information Center

International Nuclear Information System (INIS)

Oland, C.B.; Naus, D.J.

1990-01-01

The US Nuclear Regulatory Commission has initiated a Structural Aging Program at the Oak Ridge National Laboratory to identify potential structural safety issues related to continued service of nuclear power plants and to establish criteria for evaluating and resolving these issues. One of the tasks in this program focuses on the establishment of a Structural Materials Information Center where data and information on the time variation of concrete and other structural material properties under the influence of pertinent environmental stressors and aging factors are being collected and assembled into a data base. This data base will be used to assist in the prediction of potential long-term deterioration of critical structural components in nuclear power plants and to establish limits on hostile environmental exposure for these structures and materials. Two complementary data base formats have been developed. The Structural Materials Handbook is an expandable, hard-copy reference document that contains complete sets of data and information for selected portland cement concrete, metallic reinforcement, prestressing tendon, and structural steel materials. Baseline data, reference properties and environmental information are presented in the handbook as tables, notes and graphs. The handbook, which will be published in four volumes, serves as the information source for the electronic data base. The Structural Materials Electronic Data Base is accessible by an IBM-compatible personal computer and provides an efficient means for searching the various data base files to locate materials with similar properties. Properties will be reported in the International System of Units (SI) and in customary units whenever possible. 7 refs., 3 figs., 4 tabs

The strength evaluation and σ-phase aging behavior of cast stainless steel

International Nuclear Information System (INIS)

Kwon, Jae Do; Park, Joong Cheul; Lee, Woo Ho; Jang, Sun Sik

1999-01-01

σ-phase of cast stainless steel(CF8M) was artificially precipitated by means of thermal aging at 700 deg C with various holding time (0.33, 5, 15, 50 and 150 hrs) to evaluate the behavior of thermal aging status of strength change. The structure observation, hardness test, tensile test, impact test and fatigue crack growth rates test for as-received and degraded material were also performed to evaluate static strength, toughness and fatigue crack growth behavior corresponding to the aging condition of CF8M. The results showed that the area fraction of σ-phase and hardness value increased with thermal aging time. But, for the impact values, upper shelf energy decreased and fatigue crack growth rates increased with σ-phase aging progressed than that of virgin material

Assessment of core structural materials and surveillance programme of research reactors. Report of the consultants meeting. Working material

International Nuclear Information System (INIS)

2009-01-01

A series of presentations on the assessment of core structural components and materials at their facilities were given by the experts. The different issues related to degradation mechanisms were discussed. The outputs include a more thorough understanding of the specific challenges related to Research Reactors (RRs) as well as proposals for activities which could assist RR organizations in their efforts to address the issues involved. The experts recommend that research reactor operators consider implementation of surveillance programs for materials of core structural components, as part of ageing management program (TECDOC-792 and DS-412). It is recognised by experts that adequate archived structural material data is not available for many RRs. Access to this data and extension of existing material databases could help many operating organisations extend the operation of their RRs. The experts agreed that an IAEA Technical Meeting (TM) on Assessment of Core Structural Materials should be organised in December 2009 (IAEA HQ Vienna). The proposed objectives of the TM are: (i) exchange of detailed technical information on the assessment and ageing management of core structural materials, (ii) identification of materials of interest for further investigation, (iii) proposal for a new IAEA CRP on Assessment of Core Structural Materials, and (iv) identification of RRs prepared to participate in proposed CRP. Based on the response to a questionnaire prepared for the 2008 meeting of the Technical Working Group for Research Reactors, the number of engineering capital projects related to core structural components is proportionally lower than those related to,for example, I and C or electrical power systems. This implies that many operating research reactors will be operating longer using their original core structural components and justifies the assessment and evaluation programmes and activities proposed in this report. (author)

Chemical segregation behavior under thermal aging of the low-activation F82H-modified steel

International Nuclear Information System (INIS)

Lapena, J.; Garcia-Mazario, M.; Fernandez, P.; Lancha, A.M.

2000-01-01

In this work, thermal aging of the low-activation F82H-modified steel has been performed at temperatures in the range 300-600 deg. C during periods up to 5000 h. A detailed mechanical and microstructural characterization has been carried out in the aged materials, as well as in the as-received state material for reference. Auger electron spectroscopy (AES) analysis has been performed for these materials to study the microchemistry at the grain boundaries. The results show a decrease of the impact properties after aging at 600 deg. C that has been related to the precipitation of the Laves phase. Auger analyses show chromium enrichment and iron depletion at grain boundaries in all material conditions. In addition, sulphur and tungsten have been observed by this technique at grain boundaries, their presence and distribution being dependent on the material state

Estimation of radioactivity in structural materials of ETRR-1 reactor

Energy Technology Data Exchange (ETDEWEB)

Imam, M [National Center for Nuclear Safety and Radiation Control Atomic Energy Authority, Cairo (Egypt)

1997-12-31

Precise knowledge of the thermal neutron flux in the different structural materials of a reactor is necessary to estimate the radioactive inventory in these materials that are needed in any decommissioning study of the reactor. ETRR-1 is a research reactor that went critical on 2/1691. In spite of this long age of the reactor, the effective operation time of this reactor is very short since the reactor was shutdown for long periods. Because of this long age one may think of reactor decommissioning. For this purpose, the radioactivity of the reactor structural materials was estimated. Apart from the reactor core, the important structural materials in the ETRR-1 are the reactor tank, shielding concrete, and the graphite thermal column. The thermal neutron flux was determined by the monte Carlo method in these materials and the isotope inventory and the radioactivity were calculated by the international code ORIGEN-JR. 1 fig.

Monitoring ageing of components in nuclear plants

International Nuclear Information System (INIS)

Fritz, M.R.

1992-01-01

There are several mechanisms of ageing or damage in nuclear components, of which the best known can be classified into three categories: generalized damage mechanisms (wear, corrosion, erosion,...), local damage phenomena (fatigue, corrosion,...) and material property degradations. For ageing evaluation, the first requirement is a good understanding of the damage mechanisms and the determination of the kinetic laws and major influencing factors. When these factors are measurable physical parameters, ageing monitoring and periodic evaluation of damage level become possible. From the set of tools available for ageing evaluation, four are presented here in more detail: the transient logging procedure, the defect injuriousness analysis, the fatigue meter, the probabilistic approach to structural integrity. (author)

Monitoring ageing of components in nuclear plants

Energy Technology Data Exchange (ETDEWEB)

Fritz, M R [FRAMATOME, Paris (France)

1992-07-01

There are several mechanisms of ageing or damage in nuclear components, of which the best known can be classified into three categories: generalized damage mechanisms (wear, corrosion, erosion,...), local damage phenomena (fatigue, corrosion,...) and material property degradations. For ageing evaluation, the first requirement is a good understanding of the damage mechanisms and the determination of the kinetic laws and major influencing factors. When these factors are measurable physical parameters, ageing monitoring and periodic evaluation of damage level become possible. From the set of tools available for ageing evaluation, four are presented here in more detail: the transient logging procedure, the defect injuriousness analysis, the fatigue meter, the probabilistic approach to structural integrity. (author)

Annual review of materials science. Volume 7

International Nuclear Information System (INIS)

Huggins, R.A.; Bube, R.H.; Roberts, R.W.

1977-01-01

A review is presented of recent materials science research. Topics covered include: point defects and their interaction; defect chemistry in crystalline solids; deep level impurities in semiconductors; structural aspects of one-dimensional conductors; structural transformations during aging of metal alloys; high rate thick film growth; metal forming, the application of limit analysis; kinetics and mechanisms of gas-metal interactions; erosion; reversible temper embrittlement; acoustic emission in brittle materials; capacitance transient spectroscopy; hot corrosion of high-temperature alloys; fundamental optical phenomena in infrared window materials; dental amalgam; and transparent conducting coatings

Factors associated with occupational exposure to biological material among nursing professionals.

Science.gov (United States)

Negrinho, Nádia Bruna da Silva; Malaguti-Toffano, Silmara Elaine; Reis, Renata Karina; Pereira, Fernanda Maria Vieira; Gir, Elucir

2017-01-01

to identify factors associated with occupational exposure to biological material among nursing professionals. a cross-sectional study was conducted in a high complexity hospital of a city in the state of São Paulo, Brazil. Nursing professionals were interviewed from March to November 2015. All ethical aspects were observed. among the 226 professionals interviewed, 17.3% suffered occupational exposure to potentially contaminated biological material, with 61.5% being percutaneous. Factors such as age (p=0.003), professional experience in nursing (p=0.015), and experience at the institution (p=0.032) were associated with the accidents with biological material. most accidents with biological material among nursing professionals were percutaneous. Age, professional experience, and experience at the institution were considered factors associated with occupational exposure.

Behaviour of organic materials in radiation environment

CERN Document Server

Tavlet, M

2000-01-01

Radiation effects in polymers are reminded together with the ageing factors. Radiation-ageing results are mainly discussed about thermosetting insulators, structural composites and cable-insulating materials. Some hints are given about high-voltage insulations, cooling fluids, organic scintillators and light-guides. Some parameters to be taken into account for the estimate of the lifetime of components in radiation environment are also shown. (23 refs).

Marble Ageing Characterization by Acoustic Waves

Science.gov (United States)

Boudani, Mohamed El; Wilkie-Chancellier, Nicolas; Martinez, Loïc; Hébert, Ronan; Rolland, Olivier; Forst, Sébastien; Vergès-Belmin, Véronique; Serfaty, Stéphane

In cultural heritage, statue marble characterization by acoustic waves is a well-known non-destructive method. Such investigations through the statues by time of flight method (TOF) point out sound speeds decrease with ageing. However for outdoor stored statues as the ones in the gardens of Chateau de Versailles, ageing affects mainly the surface of the Carrara marble. The present paper proposes an experimental study of the marble acoustic properties variations during accelerated laboratory ageing. The surface degradation of the marble is reproduced in laboratory for 29 mm thick marble samples by using heating/cooling thermal cycles on one face of a marble plate. Acoustic waves are generated by 1 MHz central frequency contact transducers excited by a voltage pulse placed on both sides of the plate. During the ageing and by using ad hoc transducers, the marble samples are characterized in transmission, along their volume by shear, compressional TOF measurements and along their surface by Rayleigh waves measurements. For Rayleigh waves, both TOF by transducers and laser vibrometry methods are used to detect the Rayleigh wave. The transmission measurements point out a deep decrease of the waves speeds in conjunction with a dramatic decrease of the maximum frequency transmitted. The marble acts as a low pass filter whose characteristic frequency cut decreases with ageing. This pattern occurs also for the Rayleigh wave surface measurements. The speed change in conjunction with the bandwidth translation is shown to be correlated to the material de-structuration during ageing. With a similar behavior but reversed in time, the same king of phenomena have been observed trough sol-gel materials during their structuration from liquid to solid state (Martinez, L. et all (2004). "Chirp-Z analysis for sol-gel transition monitoring". Ultrasonics, 42(1), 507-510.). A model is proposed to interpret the acoustical measurements

Aromatherapy Oils: Commodities, Materials, Essences

Directory of Open Access Journals (Sweden)

Ruth Barcan

2014-08-01

Full Text Available This article examines the essential oils that are the central tools of aromatherapy and uses them as a case study for different approaches to material culture. It considers the conceptual and political implications of thinking of essential oils as, in turn, commodities, materials and essences. I argue that both cultural studies and aromatherapy have something to learn from each other. Classic materialist approaches might do well to focus more attention on the material properties and effects of things. Aromatherapy, on the other hand, could benefit from the enriched political understanding associated with classic materialist critique. New materialist strains of cultural studies may also find the vibrancy of matter that underpins many CAM/New Age practices worthy of examination.

Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications

CERN Document Server

American Society for Testing and Materials. Philadelphia

2007-01-01

1.1 This practice covers a testing methodology for evaluating absorptive materials used in flat plate or concentrating collectors, with concentrating ratios not to exceed five, for solar thermal applications. This practice is not intended to be used for the evaluation of absorptive surfaces that are (1) used in direct contact with, or suspended in, a heat-transfer liquid, (that is, trickle collectors, direct absorption fluids, etc.); (2) used in evacuated collectors; or (3) used in collectors without cover plate(s). 1.2 Test methods included in this practice are property measurement tests and aging tests. Property measurement tests provide for the determination of various properties of absorptive materials, for example, absorptance, emittance, and appearance. Aging tests provide for exposure of absorptive materials to environments that may induce changes in the properties of test specimens. Measuring properties before and after an aging test provides a means of determining the effect of the exposure. 1.3 Th...

Cutting and machining energetic materials with a femtosecond laser

Energy Technology Data Exchange (ETDEWEB)

Roeske, Frank; Benterou, Jerry; Lee, Ronald; Roos, Edward [Energetic Materials Center, Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA 94550 (United States)

2003-04-01

A femtosecond (fs) laser has been used as a tool for solving many problems involving access, machining, disassembly, inspection and avoidance of undesirable hazardous waste streams in systems containing energetic materials. Because of the unique properties of the interaction of ultrashort laser pulses with matter, the femtosecond laser can be used to safely cut these energetic materials in a precise manner without creating an unacceptable waste stream. Many types of secondary high explosives (HE) and propellants have been cut with the laser for a variety of applications ranging from disassembly of aging conventional weapons (demilitarization), inspection of energetic components of aging systems to creating unique shapes of HE for purposes of initiation and detonation physics studies. Hundreds of samples of energetic materials have been cut with the fs laser without ignition and, in most cases, without changing the surface morphology of the cut surfaces. The laser has also been useful in cutting nonenergetic components in close proximity to energetic materials. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Elastodynamic spot testing - assessing serviceability of aging elastomer parts

International Nuclear Information System (INIS)

Gracie, B.; Metcalfe, R.; Wensel, R.

1995-01-01

The properties of all polymers change with time as a function of their environment. Traditional practice has been to replace these parts according to generic time limits based on estimates of worst case material properties and conditions. This is overly-conservative in many cases, and creates unnecessary maintenance work and costs for replacement and disposal. Much of this could be avoided if the serviceability of elastomeric parts such as seals, diaphragms, gaskets, cable insulation and hoses could be reassessed on a routine basis. Elastodynamic spot testing offers a way to do this. Parts can be sampled while in service or storage to compare their as-new and used (or aged) elastodynamic properties. This data can usually be correlated with the results of functional tests to prove that material properties have not degraded to the point where the part could fail. This spot testing is similar to a micro-hardness test, but includes stress-relaxation and subsequent recovery. It provides a nondestructive means to assess the effective age of the material at a point, or several points, on a part. Sampling of hardness alone is rarely sufficient to know whether a part is still functional because this overlooks the material's viscoelastic and strength properties. An elastodynamic spot tester has been used to test different sizes, shapes and hardnesses of elastomeric parts at different levels of strain, i.e., indentation depths. An initial test program has given informative relaxation and recovery data, showing repeatability and comparing well with finite element analysis of the indentation process. Tests of aged 0-rings and diaphragms have revealed different elastodynamic properties, depending on the elastomer compound and aging conditions. (author)

The Global Age NGIOA @ Risk

CERN Document Server

Pandya, Jayshree

2012-01-01

Dr. Jayshree Pandya, founder of Risk Group LLC, is ahead of the curve in addressing the changing global fundamentals of the emerging Global Age.   The Global Age, and its changing global fundamentals has brought complex, chaotic, and turbulent times for every nation—where failures on all levels have become self-evident, repetitive, destructive, and potentially hopeless in nature and uncertainty. Nations are caught off guard.   From what is visible worldwide today, the promise of progress and prosperity for all nations does not seem to have materialized in this Global Age. Instead of progress and prosperity, we see crisis and catastrophe  overpowering and overwhelming the capability of most nations to meet their promise of progress and prosperity. Nations are in crisis. This introductory book addresses the global shifts and the changing global fundamentals of the Global Age, to lay out a much needed foundation of an integrated NGIOA risk governance framework for the near future. This book will make a conv...

Regulatory Assessment Technologies for Aging of Reactor Vessel Internals

Energy Technology Data Exchange (ETDEWEB)

Jhung, Myung Jo; Park, Jeong Soon; Ko, Hanok [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2013-10-15

In order to develop the audit calculation system, it is required to develop crack evaluation, seismic analysis and thermal-hydraulic analysis techniques for RVIs so that integrity of RVIs under the aging environment can be evaluated and be assured. In addition, regulatory requirements including safety review and inspection guides should be developed in order to assure the quality and uniformity of safety reviews and inspections regarding aging assessment and management of RVIs. Since Reactor Vessel Internals (RVIs) are installed within the reactor pressure vessel and surround the fuel assemblies, some of them are exposed to the environment such as high neutron irradiation, high temperature and reactor coolant flow. Those environmental factors can cause damage to RVIs including cracks, loss of material, fatigue, loss of fracture toughness and change of dimension as the operation time of nuclear power plants (NPPs) increases. For long-term operation more than 40 years, aging management of RVIs is important. The final objectives of this study are to establish the audit calculation system for RVIs and to develop regulatory requirements for aging assessment and management of RVIs considering their operating conditions, materials, and possible aging mechanisms.

Aging management and life extension - Containment aging study

International Nuclear Information System (INIS)

Tai, Tom M.; Deng, Daniel

2004-01-01

Bechtel is currently completing an aging study on a concrete containment structure. The target plant is a two-unit PWR plant with a generating capacity of about 850 MWe from each unit. Both units are less than 20 years old. The total electrical energy output from this plant site accounts for more than 50% of the utility's baseload operation. Although no utility in the United States has made a decision to submit a license renewal application, some have begun to investigate the feasibility of developing an life cycle management (LCM) program for a strategy to operate their plants efficiently, to investigate the financial benefit and safety implications of license renewal to operate their nuclear power plants beyond their current licensed periods, and to prepare a program plan for plant decommissioning. The LCM program includes economic, environmental, regulatory and technical aspects of continuing plant operations beyond the current license period. The Electric Power Research Institute (EPRI) has been supportive to assist utilities and owners groups in their research and development efforts to develop the technical requirements and the issues associated with important to license renewal structures. The focus of this paper is on the technical issues related to the evaluation of the material condition of the containment structure with respect to aging and the effective management of that aging. (author)

Experimental Investigation on Asphalt Binders Ageing Behavior and Rejuvenating Feasibility in Multicycle Repeated Ageing and Recycling

Directory of Open Access Journals (Sweden)

Yihua Nie

2018-01-01

Full Text Available Multicycle repeated utilization of reclaimed asphalt pavement (RAP is a quite recent development of sustainable pavement materials technology. To investigate ageing rules and recycling possibility of asphalt binders in repeatedly used asphalt mixture, virgin asphalt AH-70 samples were heated by the rolling thin film oven test (RTFOT at 163°C, respectively, for 40, 85, 180, 240, and 300 minutes to simulate different ageing degrees, and then the aged ones were rejuvenated by adding a self-made rejuvenator. This ageing and recycling process was repeated altogether for 5 cycles to simulate repeated use of RAP binders. In repeated recycling, rejuvenator contents for different cycle numbers or ageing durations were not the same, and the optimum ones were initially estimated by an empirical formula and finally obtained by comparative tests. Empirical rheological tests and the infrared spectral (IR analysis were done before and after each cycle of recycling. Results indicate that for impact on deterioration of asphalt binders, ageing time is more important than cycle number. Meanwhile, the asphalt after multicycle repeated ageing and recycling can be restored to the empirical rheological indices level of the virgin asphalt and meet specifications requirements.

Energy materials

CERN Document Server

Bruce, Duncan W; Walton, Richard I

2011-01-01

In an age of global industrialisation and population growth, the area of energy is one that is very much in the public consciousness. Fundamental scientific research is recognised as being crucial to delivering solutions to these issues, particularly to yield novel means of providing efficient, ideally recyclable, ways of converting, transporting and delivering energy. This volume considers a selection of the state-of-the-art materials that are being designed to meet some of the energy challenges we face today. Topics are carefully chosen that show how the skill of the synthetic chemist can

Comparative Investigation on the Performance of Modified System Poles and Traditional System Poles Obtained from PDC Data for Diagnosing the Ageing Condition of Transformer Polymer Insulation Materials

Directory of Open Access Journals (Sweden)

Jiefeng Liu

2018-02-01

Full Text Available The life expectancy of a transformer is largely depended on the service life of transformer polymer insulation materials. Nowadays, several papers have reported that the traditional system poles obtained from polarization and depolarization current (PDC data can be used to assess the condition of transformer insulation systems. However, the traditional system poles technique only provides limited ageing information for transformer polymer insulation. In this paper, the modified system poles obtained from PDC data are proposed to assess the ageing condition of transformer polymer insulation. The aim of the work is to focus on reporting a comparative investigation on the performance of modified system poles and traditional system poles for assessing the ageing condition of a transformer polymer insulation system. In the present work, a series of experiments have been performed under controlled laboratory conditions. The PDC measurement data, degree of polymerization (DP and moisture content of the oil-immersed polymer pressboard specimens were carefully monitored. It is observed that, compared to the relationships between traditional system poles and DP values, there are better correlations between the modified system poles and DP values, because the modified system poles can obtain much more ageing information on transformer polymer insulation. Therefore, the modified system poles proposed in the paper are more suitable for the diagnosis of the ageing condition of transformer polymer insulation.

Ageing sintered silver: Relationship between tensile behavior, mechanical properties and the nanoporous structure evolution

Energy Technology Data Exchange (ETDEWEB)

Gadaud, Pascal; Caccuri, Vincenzo; Bertheau, Denis [Institut Pprime, Dept. Phys. Mech. Mat., UPR CNRS 3346, ENSMA, Université de Poitiers, 1 av. Clément Ader, Téléport 2, 86961 Futuroscope – Chasseneuil (France); Carr, James [HMXIF, Materials Science Centre, The University of Manchester, M13 9PL (United Kingdom); Milhet, Xavier, E-mail: xavier.milhet@ensma.fr [Institut Pprime, Dept. Phys. Mech. Mat., UPR CNRS 3346, ENSMA, Université de Poitiers, 1 av. Clément Ader, Téléport 2, 86961 Futuroscope – Chasseneuil (France)

2016-07-04

Silver pastes sintering is a potential candidate for die bonding in power electronic modules. The joints, obtained by sintering, exhibit a significant pore fraction thus reducing the density of the material compared to bulk silver. This was shown to alter drastically the mechanical properties (Young's modulus, yield strength and ultimate tensile stress) at room temperature. While careful analysis of the microstructure has been reported for the as-sintered material, little is known about its quantitative evolution (pores and grains) during thermal ageing. To address this issue, sintered bulk specimens and sintered joints were aged either under isothermal conditions (125 °C up to 1500 h) or under thermal cycling (between −40 °C/+125 °C with 30 min dwell time at each temperature for 2400 cycles). Under these conditions, it is shown that the density of the material does not change but the sub-micron porosity evolves towards a broader size distribution, consistent with Oswald ripening. It is also shown that only the step at 125 °C during the non-isothermal ageing is responsible for the microstructure evolution: isothermal ageing at high temperature can be regarded as a useful tool to perform accelerated ageing tests. Tensile properties are investigated as both a function of ageing time and a function of density. It is shown that the elastic properties do not evolve with the ageing time unlike the plastic properties. This is discussed as a function of the material microstructure evolution.

Photonic band gap materials: Technology, applications and challenges

International Nuclear Information System (INIS)

Johri, M.; Ahmed, Y.A.; Bezboruah, T.

2006-05-01

Last century has been the age of Artificial Materials. One material that stands out in this regard is the semiconductor. The revolution in electronic industry in the 20th century was made possible by the ability of semiconductors to microscopically manipulate the flow of electrons. Further advancement in the field made scientists suggest that the new millennium will be the age of photonics in which artificial materials will be synthesized to microscopically manipulate the flow of light. One of these will be Photonic Band Gap material (PBG). PBG are periodic dielectric structures that forbid propagation of electromagnetic waves in a certain frequency range. They are able to engineer most fundamental properties of electromagnetic waves such as the laws of refraction, diffraction, and emission of light from atoms. Such PBG material not only opens up variety of possible applications (in lasers, antennas, millimeter wave devices, efficient solar cells photo-catalytic processes, integrated optical communication etc.) but also give rise to new physics (cavity electrodynamics, localization, disorder, photon-number-state squeezing). Unlike electronic micro-cavity, optical waveguides in a PBG microchip can simultaneously conduct hundreds of wavelength channels of information in a three dimensional circuit path. In this article we have discussed some aspects of PBG materials and their unusual properties, which provided a foundation for novel practical applications ranging from clinical medicine to information technology. (author)

Mechanism and materialism British natural philosophy in the age of reason

CERN Document Server

Schofield, Robert E

1970-01-01

Robert Schofield explores the rational elements of British experimental natural philosophy in the 18th century by tracing the influence of two opposing concepts of the nature of matter and its action-mechanism and materialism. Both concepts rested on the Newtonian interpretation of their proponents, although each developed more or less independently. By integrating the developments in all the areas of experimental natural philosophy, describing their connections and the influences of Continental science, natural theology, and to a lesser degree social and institutional changes, the author dem

Characterization of rhenium compounds obtained by electrochemical synthesis after aging process

Energy Technology Data Exchange (ETDEWEB)

Vargas-Uscategui, Alejandro, E-mail: avargasuscat@ing.uchile.cl [Departamento de Ingeniería de Minas, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile); Mosquera, Edgar [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile); López-Encarnación, Juan M. [Department of Mathematics-Physics and Department of Chemistry, University of Puerto Rico at Cayey, 205 Ave. Antonio R. Barceló, Cayey, PR 00736, USA. (Puerto Rico); Chornik, Boris [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada Av. 2008, Santiago (Chile); Katiyar, Ram S. [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico San Juan, San Juan, PR 00931-3343 (United States); Cifuentes, Luis [Departamento de Ingeniería de Minas, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile)

2014-12-15

The proper identification of the molecular nature of the aged rhenium compound obtained by means of electrodeposition from an alkaline aqueous electrolyte was determined. Chemical, structural and vibrational experimental characterization of the aged Re compound showed agreement with quantum-computations, thereby allowing the unambiguous identification of the Re compound as H(ReO{sub 4})H{sub 2}O. - Graphical abstract: Rhenium oxides were electrodeposited on a copper surface and after environmental aging was formed the H(ReO{sub 4})H{sub 2}O compound. The characterization of the synthesized material was made through the comparison of experimental evidence with quantum mechanical computations carried out by means of density functional theory (DFT). - Highlights: • Aged rhenium compound obtained by means of electrodeposition was studied. • The study was made by combining experimental and DFT-computational information. • The aged electrodeposited material is consistent with the H(ReO{sub 4})H{sub 2}O compound.

Materials for 300 to 5000C magnetic components

International Nuclear Information System (INIS)

Weichold, M.H.; Pandey, R.K.; Palmer, D.W.

1980-01-01

Core materials and winding wire for audio and rf transformers have been investigated to 500 0 C. Audio cores of 2 V Permendur had parameter stability from 25 to 500 0 C and during aging at 450 0 C. High frequency ferrite material, Mix 63, displayed usefulness up to 300 0 C. Both anodized aluminum and ceramic-coated copper wire function to 500 0 C in low voltage or large gauge applications. Components based on these materials operate reliably to 500 0 C

Ethical issues in ageing and biography.

Science.gov (United States)

Kenyon, G M

1996-11-01

The increasing use of biographical materials in research and intervention in the field of ageing gives rise to significant ethical issues. In this inquiry, four of these issues are explicated. First, the notion of informed consent is explored in relation to selected contexts of research and intervention in ageing and biography. Second, the issues of autonomy and competence are considered from the point of view of identifying contexts where biography is a prerequisite for ethically responsive action. The third ethical issue concerns respecting the groundrules of various biographical approaches. Finally, the notions of authenticity and truth in lifestories are explored in an attempt to clarify the limitations and expectations of ageing and biography. The discussion of these ethical issues proceeds on the basis of an argument that indicates the fundamental importance of biographical ageing or the stories we are.

Raw material variability as archaeological tools: Preliminary results from a geochemical study of the basalt vessel workshop at Iron Age Tel Hazor, Israel

Directory of Open Access Journals (Sweden)

Tatjana Gluhak

2016-10-01

Full Text Available The discovery of a basalt vessel workshop at Tel Hazor, one of the most important Iron Age sites in the Near East, marks a turning point in our understanding of stone artifact production and distribution during the1st millennium BCE. It offers a rare opportunity to characterize ancient raw material sources, production sites, and study production, trade and distribution systems. The basalt vessel workshop, the only one of its kind in the Levant, produced large quantities of bowl preforms and production waste. To better understand the production and distribution systems behind this specialized production center, in 2011 we initiated a focused geochemical project that concentrated on the products of this unique workshop.  We measured the major and trace element composition of 44 unfinished basalt vessels from the workshop and other contexts at Hazor, and can demonstrate that the majority of these objects were derived from one specific, geochemically well-constrained, basaltic rock source. Only a few bowls clearly deviate from this geochemical composition and were produced using raw material from other sources. Thus, we believe that one major quarry existed that supplied the Hazor workshop with the majority of the basaltic raw material. The products from this specific extraction site provide us with a “Hazor reference group” that can be used to test whether or not finished vessels from Hazor and contemporary sites were produced in the Hazor workshop.

Long-term aging of recycled binders : [summary].

Science.gov (United States)

2015-10-01

At 80 million tons a year representing more than 80% of all milled asphalt pavement : asphalt paving is Americas most recycled material. Asphalt can be recycled in place, which is : very cost effective; however, aging of recycled binder ca...

Storage depot for radioactive material

International Nuclear Information System (INIS)

Szulinski, M.J.

1983-01-01

Vertical drilling of cylindrical holes in the soil, and the lining of such holes, provides storage vaults called caissons. A guarded depot is provided with a plurality of such caissons covered by shielded closures preventing radiation from penetrating through any linear gap to the atmosphere. The heat generated by the radioactive material is dissipated through the vertical liner of the well into the adjacent soil and thus to the ground surface so that most of the heat from the radioactive material is dissipated into the atmosphere in a manner involving no significant amount of biologically harmful radiation. The passive cooling of the radioactive material without reliance upon pumps, personnel, or other factor which might fail, constitutes one of the most advantageous features of this system. Moreover this system is resistant to damage from tornadoes or earthquakes. Hermetically sealed containers of radioactive material may be positioned in the caissons. Loading vehicles can travel throughout the depot to permit great flexibility of loading and unloading radioactive materials. Radioactive material can be shifted to a more closely spaced caisson after ageing sufficiently to generate much less heat. The quantity of material stored in a caisson is restricted by the average capacity for heat dissipation of the soil adjacent such caisson

Aging studies of batteries and transformers in class IE power systems

International Nuclear Information System (INIS)

Edson, J.L.; Roberts, E.W.

1992-01-01

A Phase I aging study of batteries used in 1E Power Systems of nuclear power plants concluded that significant aging effects for aged batteries are growth of positive plants, loosening of active material in plates that have grown, loss of active material caused by gassing and corrosion, and embrittlement of the lead grids and straps. These effects contribute to decreased electrical capacity and decreased seismic ruggedness which, during a seismic event, can lead to decreased electrical performance or complete failure. Subsequently a Phase II test program was conducted to determine if seismic ruggedness of aged batteries can be inadequate even if the electrical capacity is satisfactory, as determined by tests recommended by IEEE Std 450-1987, open-quote IEEE Recommended Practice for Maintenance, Testing, and Replacement of Large Storage Batteries for Generating Stations and Substations.close quotes In addition, a Phase I aging study of transformers in 1E Power Systems was performed to identify stressors and failure mechanisms, investigate whether transformers are showing the effects of aging as they grow older, and to determine if current surveillance methods are effective in mitigating aging effects. This paper presents the results of these studies

Effect of Thermal Aging on the Corrosion Behavior of Wrought and Welded Alloy 22

International Nuclear Information System (INIS)

Rebak, R.B.; Edgecumbe Summers, T.S.; Lian, T.

2002-01-01

Alloy 22 (UNS N06022) is a candidate material for the external wall of the high level nuclear waste containers for the potential repository site at Yucca Mountain. In the mill-annealed (MA) condition, Alloy 22 is a single face centered cubic phase. When exposed to temperatures on the order of 600 C and above for times higher than 1 h, this alloy may develop secondary phases that are brittle and offer a lower corrosion resistance than the MA condition. The objective of this work was to age Alloy 22 at temperatures between 482 C and 800 C for times between 0.25 h and 3,000 h and to study the corrosion performance of the resulting material. Aging was carried out using wrought specimens as well as gas tungsten arc welded (GTAW) specimens. The corrosion performance was characterized using standard immersion tests in aggressive acidic solutions and electrochemical tests in multi-component solutions. Results show that, in general, in aggressive acidic solutions the corrosion rate increased as the aging temperature and aging time increased. However, in multi ionic environments that could be relevant to the potential Yucca Mountain site, the corrosion rate of aged material was the same as the corrosion rate of the MA material

Structural Aging Program approach to providing an improved basis for aging management of safety-related concrete structures

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.

1993-01-01

The Structural Aging (SAG) Program is being conducted at the Oak Ridge National Laboratory (ORNL) for the United States Nuclear Regulatory Commission (USNRC). The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. The program is organized into four tasks: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for Continued Service Determinations. Objectives and a summary of recent accomplishments under each of these tasks are presented

Estimation of embrittlement during aging of AISI 316 stainless steel ...

Indian Academy of Sciences (India)

Unknown

rical relation connecting the aging temperature, aging time and nitrogen ... strength, high tensile strength, are easy to fabricate and ... However, the ferrite is a metastable phase which ... 2. Experimental. 2.1 Materials. Nuclear grade AISI 316 stainless steel plates ( .... fore, it is desirable to develop empirical relations con-.

A materials engineering view of license renewal at the US Nuclear Regulatory Commission

International Nuclear Information System (INIS)

Banic, M.

1999-01-01

This paper discusses the treatment of license renewal at the US Nuclear Regulatory Commission (NRC) with emphasis on the review process by the staff of the Materials and Chemical Engineering Branch (EMCB). The paper covers the rules governing license renewal, the applications received, the schedule, the approach, and the technical issues. The NRC has a tight schedule of 30-36 months to renew a license. To date, Baltimore Gas and Electric (BG and E) and Duke Power have applied for license renewal. Expecting more applicants, the staff has taken steps to address the public's concern that the effects of aging will be adequately managed and the industry's concern that the reviews will be timely, efficient, and uniform. These steps include identifying aging effects and making the results available in a report and computerized database, approving topical reports and aging management programs for generic use, and reviewing aging management programs according to specific criteria. Materials Engineering staff have a major role because many of the aging issues are materials related. (author)

CEO age and gender: Subsequent market performance

Directory of Open Access Journals (Sweden)

Marcelo Eduardo

2016-12-01

Full Text Available The issue of CEO age and gender vs. concurrent performance is extensively examined, but the association with subsequent performance has limited treatment in the financial literature, and with conflicting findings. In the current study, we examine the association between CEO age and gender, and subsequent company market performance using a more recent set of observations and the standard four-factor model to estimate future cumulative abnormal shareholder returns. We find that subsequent abnormal shareholder returns are marginally significantly higher for female CEOs than for their male counterparts, but no material pattern is observed between CEO age and subsequent abnormal shareholder return performance.

Preventive maintenance-A countermeasure to plant aging

International Nuclear Information System (INIS)

Hlubek, W.

1985-01-01

The aging of power plants is caused by manifold and different influences. For instance, mechanical and thermal stress, radiation exposure, denting or wastage can considerably affect the aging of plant components and thus cause premature failures of components. In this presentation, the term 'Plant Aging' in nuclear power plants is to be understood more comprehensively than wear on components and material fatigue. In addition, nuclear power plants are to be adjusted to the advancing state of the science and technology (state-of-the-art) in order to guarantee safe operation at all times. The preventive maintenance - as a countermeasure to plant aging - comprises the systematic checks and servicing of the plant systems in operation and follows aging by inspection and tests. Experience with Rheinisch-Westfaelisches Elektrizitaetswerk AG (RWE) preventive maintenance program at the Biblis NNP (1300 MW, PWR) is discussed. The concept of an 'Integrated Maintenance System' as a means to avoid 'Plant Aging' is presented

Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures

Science.gov (United States)

McManus, Hugh L.; Chamis, Christos C.

1996-01-01

This report describes analytical methods for calculating stresses and damage caused by degradation of the matrix constituent in polymer matrix composite materials. Laminate geometry, material properties, and matrix degradation states are specified as functions of position and time. Matrix shrinkage and property changes are modeled as functions of the degradation states. The model is incorporated into an existing composite mechanics computer code. Stresses, strains, and deformations at the laminate, ply, and micro levels are calculated, and from these calculations it is determined if there is failure of any kind. The rationale for the model (based on published experimental work) is presented, its integration into the laminate analysis code is outlined, and example results are given, with comparisons to existing material and structural data. The mechanisms behind the changes in properties and in surface cracking during long-term aging of polyimide matrix composites are clarified. High-temperature-material test methods are also evaluated.

Bacterial biodegradation of melamine-contaminated aged soil: influence of different pre-culture media or addition of activation material.

Science.gov (United States)

Hatakeyama, Takashi; Takagi, Kazuhiro

2016-08-01

This study aimed to investigate the biodegrading potential of Arthrobacter sp. MCO, Arthrobacter sp. CSP, and Nocardioides sp. ATD6 in melamine-contaminated upland soil (melamine: approx. 10.5 mg/kg dry weight) after 30 days of incubation. The soil sample used in this study had undergone annual treatment of lime nitrogen, which included melamine; it was aged for more than 10 years in field. When R2A broth was used as the pre-culture medium, Arthrobacter sp. MCO could degrade 55 % of melamine after 30 days of incubation, but the other strains could hardly degrade melamine (approximately 25 %). The addition of trimethylglycine (betaine) in soil as an activation material enhanced the degradation rate of melamine by each strain; more than 50 % of melamine was degraded by all strains after 30 days of incubation. In particular, strain MCO could degrade 72 % of melamine. When the strains were pre-cultured in R2A broth containing melamine, the degradation rate of melamine in soil increased remarkably. The highest (72 %) melamine degradation rate was noted when strain MCO was used with betaine addition.

Explanation of enhanced mechanical degradation rate for radiation- aged polyolefins as the aging temperature is decreased

International Nuclear Information System (INIS)

Gillen, K.T.; Clough, R.L.; Wise, J.; Malone, M.G.

1994-01-01

Degradation rates are normally increased by increasing the responsible environmental stresses. We describe results for a semi-crystalline, crosslinked polyolefin material that contradicts this assumption. In particular, under combined radiation plus thermal environments, this material mechanically degrades much faster at room temperature than it does at elevated temperatures. The probable explanation for this phenomenon relates to the importance on mechanical properties of the tie molecules connecting crystalline and amorphous regions. Partial melting and reforming/ reorganization of crystallites occurs throughout the crystalline melting region (at least room temperature up to 126 C), with the rate of such processes increasing with an increase in temperature. At low temperatures, this process is sufficiently slow such that a large percentage of the radiation-damaged tie molecules will still connect the amorphous and crystalline regions at the end of aging, leading to rapid reductions in tensile properties. At higher temperatures, the enhanced annealing rate will lead, during the aging, to the establishment of new, undamaged tie molecules connecting crystalline and amorphous regions. This healing process will reduce the degradation rate. Evidence in support of this model is presented

Measurement with corrugated tubes of early-age autogenous shrinkage of cement-based material

DEFF Research Database (Denmark)

Tian, Qian; Jensen, Ole Mejlhede

2009-01-01

The use of a special corrugated mould enables transformation of volume strain into horizontal, linear strain measurement in the fluid stage. This allows continuous measurement of the autogenous shrinkage of cement-based materials since casting, and also effectively eliminates unwanted influence...

Application of X-rays to dental age estimation in medico-legal practice

Directory of Open Access Journals (Sweden)

Dorota Lorkiewicz-Muszyńska

2015-05-01

Full Text Available Aim of the study: The paper addresses the use of dental age assessment methods based on radiographs in medico-legal practice. Different cases of practical application of the methods are presented including identification of human remains, dental age assessment in a living person and one archaeological case. Material and methods : The study material consisted of cases involving dental age assessment performed in the Department of Forensic Medicine, Poznan University of Medical Sciences in Poznan. Depending on the preliminary assessment of age, the Liversidge or the Kvaal et al. methods were applied. Dental age was estimated on the basis of available pantomograms. In the case of the living person, it was a radiograph supplied for expert evaluation. In the other cases, dental computed tomography was performed. Results : Dental age was successfully estimated in all of the cases. Various methods based on the analysis of X-ray images were applied. Dental age was shown to be correlated with skeletal age. Conclusions : The methods based on radiographs were demonstrated to be useful, and the results they yield are fully correlated with results of anthropological analyses.

Review of equipment aging theory and technology. Final report

Energy Technology Data Exchange (ETDEWEB)

Carfagno, S.P.; Gibson, R.J.

1980-09-01

The theory and technology of equipment aging is reviewed, particularly as they relate to the qualification of safety-system equipment for nuclear power generating stations. A fundamental degradation model is developed, and its relation to more restricted models (e.g., Arrhenius and inverse-stress models) is shown. The most common theoretical and empirical models of aging are introduced, and limitations on their practical application are analyzed. Reliability theory and its application to the acceleration of aging are also discussed. A compendium of aging data for materials and components, including degradation mechanisms, failure modes and activation energies, is included.

Review of equipment aging theory and technology. Final report

International Nuclear Information System (INIS)

Carfagno, S.P.; Gibson, R.J.

1980-09-01

The theory and technology of equipment aging is reviewed, particularly as they relate to the qualification of safety-system equipment for nuclear power generating stations. A fundamental degradation model is developed, and its relation to more restricted models (e.g., Arrhenius and inverse-stress models) is shown. The most common theoretical and empirical models of aging are introduced, and limitations on their practical application are analyzed. Reliability theory and its application to the acceleration of aging are also discussed. A compendium of aging data for materials and components, including degradation mechanisms, failure modes and activation energies, is included

Treeing phenomenon of thermoplastic polyethylene blends for recyclable cable insulation materials

Science.gov (United States)

Li, Lunzhi; Zhang, Kai; Zhong, Lisheng; Gao, Jinghui; Xu, Man; Chen, Guanghui; Fu, Mingli

2017-02-01

Owing to its good recyclability and low processing energy consumption, non-crosslinked polyethylene blends (e.g. LLDPE-HDPE blends) are considered as one of potential environmental-friendly substitutions for crosslinked polyethylene (XLPE) as cable insulation material. Although extensive work has been performed for measuring the basic dielectric properties, there is a lack of the investigations on the aging properties for such a material system, which hinders the evaluation of reliability and lifetime of the material for cable insulation. In this paper, we study the electric aging phenomenon of 0.7LLDPE-0.3HDPE blending material by investigating the treeing behavior, and its comparison with XLPE and LLDPE. Treeing tests show that the 0.7LLDPE-0.3HDPE blends have lower probability for treeing as well as smaller treeing dimensions. Further thermal analysis and microstructure study results suggest that the blends exhibit larger proportion of thick lamellae and higher crystallinity with homogeneously-distributed amorphous region, which is responsible for good anti-treeing performance. Our finding provides the evidence that the 0.7LLDPE-0.3HDPE blends exhibits better electric-aging-retardance properties than XLPE, which may result in a potential application for cable insulation.

Treeing phenomenon of thermoplastic polyethylene blends for recyclable cable insulation materials

Directory of Open Access Journals (Sweden)

Lunzhi Li

2017-02-01

Full Text Available Owing to its good recyclability and low processing energy consumption, non-crosslinked polyethylene blends (e.g. LLDPE-HDPE blends are considered as one of potential environmental-friendly substitutions for crosslinked polyethylene (XLPE as cable insulation material. Although extensive work has been performed for measuring the basic dielectric properties, there is a lack of the investigations on the aging properties for such a material system, which hinders the evaluation of reliability and lifetime of the material for cable insulation. In this paper, we study the electric aging phenomenon of 0.7LLDPE-0.3HDPE blending material by investigating the treeing behavior, and its comparison with XLPE and LLDPE. Treeing tests show that the 0.7LLDPE-0.3HDPE blends have lower probability for treeing as well as smaller treeing dimensions. Further thermal analysis and microstructure study results suggest that the blends exhibit larger proportion of thick lamellae and higher crystallinity with homogeneously-distributed amorphous region, which is responsible for good anti-treeing performance. Our finding provides the evidence that the 0.7LLDPE-0.3HDPE blends exhibits better electric-aging-retardance properties than XLPE, which may result in a potential application for cable insulation.

ESP – Data from Restarted Life Tests of Various Silicon Materials

Energy Technology Data Exchange (ETDEWEB)

Schneider, Jim

2010-10-06

Current funding has allowed the restart of testing of various silicone materials placed in Life Tests or Aging Studies from past efforts. Some of these materials have been in test since 1982, with no testing for approximately 10 years, until funding allowed the restart in FY97. Charts for the various materials at different thickness, compression, and temperature combinations illustrate trends for the load-bearing properties of the materials.

Gender-Specific Peculiarities of Motor Preparedness of Children Aged 6-10

Directory of Open Access Journals (Sweden)

О. В. Іващенко

2017-03-01

Full Text Available The objective is to determine the gender-specific peculiarities of motor preparedness of children aged 6-10.  Materials and methods: the participants in the study were girls aged 6 (n = 36, aged 7 (n = 48, aged 8 (n = 57, aged 9 (n = 38, aged 10 (n = 46; boys aged 6 (n = 48, aged 7 (n = 45, aged 8 (n = 60, aged 9 (n = 47, aged 10 (n = 40. To achieve the tasks set, the study relied on the following research methods: analysis of scientific literature, pedagogical testing and methods of mathematical statistics of research data reduction. The study used discriminant analysis as the modeling method. Results: the classification results of motor preparedness of girls and boys aged 6-10 indicate that the study has correctly classified 81.9-100% of the initial observations. The graphic material demonstrates the density of objects within each class and a clear distinction between the classes. This allows to maintain that there is a significant difference between girls and boys aged 6-10 in their motor preparedness. Conclusions. The girls aged 6-10 show the best results in movement coordination related to combinations of movements of arms and legs, as well as flexibility. The girls aged 10 show the best results in test No. 10 “300-m Race”. The boys aged 6-10, unlike the girls, show the best results in the development of general coordination of movements, strength, speed strength, strength and general endurance. It is possible to argue with a high level of reliability that by their classification characteristics girls and boys belong to different classes, and significantly differ in motor preparedness.

Performance of materials in the component cooling water systems of pressurized water reactors

International Nuclear Information System (INIS)

Lee, B.S.

1993-01-01

The component cooling water (CCW) system provides cooling water to several important loads throughout the plant under all operating conditions. An aging assessment CCW systems in pressurized water reactors (PWRs) was conducted as part of Nuclear Plant Aging Research Program (NPAR) instituted by the US Nuclear Regulatory Commission. This paper presents some of the results on the performances of materials in respect of their application in CCW Systems. All the CCW system failures reported to the Nuclear Plant Reliability Data System (NPRDS) from January 1988 to June 1990 were reviewed; it is concluded that three of the main contributors to CCW system failures are valves, pumps, and heat exchangers. This study identified the modes and causes of failure for these components; most of the causes for the aging-related failures could be related to the performance of materials. Also, in this paper the materials used for these components are reviewed, and there aging mechanisms under CCW system conditions are discussed

Twin boundary cavitation in aged type 304 stainless steel

International Nuclear Information System (INIS)

Sikka, V.K.; Swindeman, R.W.; Brinkman, C.R.

1975-10-01

A transition from grain to twin boundary cavitation was observed in aged-and-creep-tested type 304 stainless steel. Evidence of twin boundary cavitation has also been observed for unaged material under certain test conditions. This same behavior was also found in aged type 316 stainless steel. Several possible reasons have been suggested for the absence of frequently observed grain boundary cavitation

Uncertainty assessment in gamma spectrometric measurements of plutonium isotope ratios and age

Energy Technology Data Exchange (ETDEWEB)

Ramebaeck, H., E-mail: henrik.ramebeck@foi.se [Swedish Defence Research Agency, FOI, Division of CBRN Defence and Security, SE-901 82 Umea (Sweden); Chalmers University of Technology, Department of Chemical and Biological Engineering, Nuclear Chemistry, SE-412 96 Goeteborg (Sweden); Nygren, U.; Tovedal, A. [Swedish Defence Research Agency, FOI, Division of CBRN Defence and Security, SE-901 82 Umea (Sweden); Ekberg, C.; Skarnemark, G. [Chalmers University of Technology, Department of Chemical and Biological Engineering, Nuclear Chemistry, SE-412 96 Goeteborg (Sweden)

2012-09-15

A method for the assessment of the combined uncertainty in gamma spectrometric measurements of plutonium composition and age was evaluated. Two materials were measured. Isotope dilution inductively coupled plasma sector field mass spectrometry (ID-ICP-SFMS) was used as a reference method for comparing the results obtained with the gamma spectrometric method for one of the materials. For this material (weapons grade plutonium) the measurement results were in agreement between the two methods for all measurands. Moreover, the combined uncertainty in all isotope ratios considered in this material (R{sub Pu238/Pu239}, R{sub Pu240/Pu239}, R{sub Pu241/Pu239}, and R{sub Am241/Pu241} for age determination) were limited by counting statistics. However, the combined uncertainty for the other material (fuel grade plutonium) were limited by the response fit, which shows that the uncertainty in the response function is important to include in the combined measurement uncertainty of gamma spectrometric measurements of plutonium.

Ageing management technical information investigations

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

In February 2013, there are 50 units of commercial nuclear power plants (NPPs) in Japan. We enter into a period that 20 units of them are operating for more than 30 years. Currently, regulation imposes utilities to conduct ageing technical evaluations of each unit before operation of 30 years from the commissioning, to develop the long term maintenance management policy for next 10 years and to submit to the regulatory authority the policy with the report on ageing management technical evaluation (AMTE) for each NPP. It is necessary for regulatory side to develop technical information bases incorporating latest technical knowledge as operating experiences in domestic and abroad on ageing of the plants necessary to conduct reviews of AMTE for each unit. Based on these standpoints, technical information bases investigations have been conducted from the viewpoints of material degradation of ageing NPPs. In order to develop scientific regulator judgment bases related to ageing management (AM) and long-term operation (LTO), investigations on latest information on ageing management in domestic and abroad are conducted and a set of documents including technical evaluation review manuals necessary to conduct AMTE are prepared. To utilize the results of the investigations for ageing technical evaluation, database including latest information related to AM and LTO are developed, ran and operated. In addition, investigations related to Fugen nuclear plant, under decommissioning plants, investigations on mechanism of stress corrosion cracking (SCC), thermal ageing and preventive technologies for SCC, detection and diagnosis technology for ageing degradation and condition monitoring technology are performed to validate and confirm effectiveness of the technologies. (author)

Safe ageing management of nuclear power plants: An European synthesis

International Nuclear Information System (INIS)

Grandemange, J.M.

2002-01-01

Ageing of nuclear power plants means evolution of material or equipment properties on one side, and evolution of personnel skill and procedure adequacy on the other side, both of which, after a certain time, may not be compatible with the required safety provisions, or with an economic operation of the plant. Repair or replacement of components, as well as change in service conditions for a better compatibility with component reduced capabilities can be used to mitigate ageing effects. The paper summarises the results of a study conducted in this field with the support of the European Commission. It presents: the synthesis of the work done under international auspices, and in the European context; the comparison of ageing management approaches used in several European countries with international recommendations; the summary of the various potential phenomena and their governing parameters, the methods of in-service ageing identification and possible mitigation methods; illustrative ageing management practices, taking material ageing aspects as examples. Concerning the first topic, the European report identifies 56 OECD and IAEA reports on ageing management issues, 35 being summarised in an appendix to the report. It also identifies numerous European and international studies covering topics of interest to ageing and Plant Life management. ageing management approaches have been considered from the regulatory point of view and from the utilities management point of view. Contributors to the study have identified a general consensus in Europe, with no limited time operating authorisation, the safety being a utility responsibility under continuous surveillance by the regulatory authority. Practical ageing management methods include: periodic safety reviews (PSR), a ten years periodicity being a common practice, completed by continuous ageing management taking into account safety and industrial anticipation needs; the implementation of life-time management programmes

Microstructural evolution and stress-corrosion-cracking behavior of thermally aged Ni-Cr-Fe alloy

International Nuclear Information System (INIS)

Yoo, Seung Chang; Choi, Kyoung Joon; Kim, Taeho; Kim, Si Hoon; Kim, Ju Young; Kim, Ji Hyun

2016-01-01

Highlights: • Effects of long-term thermal aging on the nickel-based Alloy 600 were investigated. • Heat treatments simulating thermal aging were conducted by considering Cr diffusion. • Nano-indentation test results show hardening of thermally aged materials. • Thermally aged materials are more susceptible to stress corrosion cracking. • The property changes are attributed to the formation and evolution of precipitates. - Abstract: To understand the effect of long-term thermal aging in power plant systems, representative thick-walled Alloy 600 was prepared and thermally aged at 400 °C to fabricate samples with thermal aging effects similar to service operating conditions. Changes of microstructures, mechanical properties, and stress corrosion cracking susceptibility were investigated mainly through electron backscatter diffraction, nanoindentation, and high-temperature slow strain rate test. The formation of abundant semi-continuous precipitates with chromium depletion at grain boundaries was observed after thermally aged for 10 equivalent years. Also, alloys thermally aged for 10 equivalent years of thermal aging exhibited the highest susceptibility to stress corrosion cracking.

Aging management of containment structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.; Graves, H.L. III; Norris, W.E.

1996-01-01

Research is being conducted by Oak Ridge National Laboratory under US nuclear regulatory commission (USNRC) sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a structural materials information center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of non-destructive evaluation techniques, assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants. (orig.)

Aging management of major LWR components with nondestructive evaluation

International Nuclear Information System (INIS)

Shah, V.N.; MacDonald, P.E.; Akers, D.W.; Sellers, C.; Murty, K.L.; Miraglia, P.Q.; Mathew, M.D.; Haggag, F.M.

1997-01-01

Nondestructive evaluation of material damage can contribute to continued safe, reliable, and economical operation of nuclear power plants through their current and renewed license period. The aging mechanisms active in the major light water reactor components are radiation embrittlement, thermal aging, stress corrosion cracking, flow-accelerated corrosion, and fatigue, which reduce fracture toughness, structural strength, or fatigue resistance of the components and challenge structural integrity of the pressure boundary. This paper reviews four nondestructive evaluation methods with the potential for in situ assessment of damage caused by these mechanisms: stress-strain microprobe for determining mechanical properties of reactor pressure vessel and cast stainless materials, magnetic methods for estimating thermal aging damage in cast stainless steel, positron annihilation measurements for estimating early fatigue damage in reactor coolant system piping, and ultrasonic guided wave technique for detecting cracks and wall thinning in tubes and pipes and corrosion damage to embedded portion of metal containments

Aging management of containment structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

1994-01-01

Research is being conducted by Oak Ridge National Laboratory under U.S. Nuclear Regulatory Commission sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the US-NRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of nondestructive evaluation techniques, assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants. (author). 29 refs., 2 figs

Aging management of containment structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.; Graves, H.L. III; Norris, W.E.

1994-01-01

Research is being conducted by ORNL under US Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of nondestructive evaluation techniques. assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants

Ageing and People with Learning Disabilities: In Search of Evidence

Science.gov (United States)

Walker, Carol

2015-01-01

Background: Growing numbers of people with learning disabilities are now living into older age. This study aims to examine the state of knowledge about their lives and the challenges that ageing has for both family carers and policymakers and practitioners. Materials and Methods: The article synthesises existing research in the fields of learning…

Maternal age and child morbidity

DEFF Research Database (Denmark)

Hviid, Malene Meisner; Skovlund, Charlotte Wessel; Mørch, Lina Steinrud

2017-01-01

the association between maternal age and overall child morbidity according to main diagnosis groups. MATERIAL AND METHODS: We conducted a national cohort study including 352 027 live firstborn singleton children. The children were born between Jan 1994 and Dec 2009 and followed to Dec 2012. Children were divided...... into groups according to maternal age: 15-24, 25-29, 30-34, and 35+ years. Poisson regression analyses calculated adjusted incidence rate ratios (IRR) of child morbidities according to main diagnoses groups A-Q of the International Classification of Disease 10 with adjustment for year of birth, body mass...... index, smoking, and mother's level of education. RESULTS: Average follow-up time was 11 years. Compared to children born to women 25-29 years, firstborn children to mothers aged 35+ had higher child morbidity in 8 of 19 main diagnosis groups and firstborn children to mothers 15-24 years had higher child...

Fetal origin of vascular aging

Directory of Open Access Journals (Sweden)

Shailesh Pitale

2011-01-01

Full Text Available Aging is increasingly regarded as an independent risk factor for development of cardiovascular diseases such as atherosclerosis and hypertension and their complications (e.g. MI and Stroke. It is well known that vascular disease evolve over decades with progressive accumulation of cellular and extracellular materials and many inflammatory processes. Metabolic syndrome, obesity and diabetes are conventionally recognized as risk factors for development of coronary vascular disease (CVD. These conditions are known to accelerate ageing process in general and vascular ageing in particular. Adverse events during intrauterine life may programme organ growth and favour disease later in life, popularly known as, ′Barker′s Hypothesis′. The notion of fetal programming implies that during critical periods of prenatal growth, changes in the hormonal and nutritional milieu of the conceptus may alter the full expression of the fetal genome, leading to permanent effects on a range of physiological.

Effect of aging on tracheal mucociliary clearance in Beagle dogs

International Nuclear Information System (INIS)

Whaley, S.L.; Muggenburg, B.A.; Wolff, R.K.

1985-01-01

Tracheal mucous velocity measurements were made in 24 Beagle dogs, in 5 age groups, using a gamma camera to detect movement on instilled radiolabeled material. Age groups were defined as immature, young adult, middle-aged, mature, and aged dogs. Mean velocities (+/- SE) were 3.6 +/- 0.4 mm/min in the immature dogs, 9.8 +/- 0.7 mm/min in the young adults, 6.9 +/- 0.5 mm/min in the middle-aged dogs, 3.6 +/- 1.1 mm/min in the mature dogs, and 2.8 +/- 0.6 mm/min in the aged dogs. Tracheal mucous velocity was significantly faster in the young adult and middle-aged groups than in the immature, mature, and aged dog groups. 4 references, 1 figure, 1 table

Color stability and degree of cure of direct composite restoratives after accelerated aging.

Science.gov (United States)

Sarafianou, Aspasia; Iosifidou, Soultana; Papadopoulos, Triantafillos; Eliades, George

2007-01-01

This study evaluated the color changes and amount of remaining C = C bonds (%RDB) in three dental composites after hydrothermal- and photoaging. The materials tested were Estelite sigma, Filtek Supreme and Tetric Ceram. Specimens were fabricated from each material and subjected to L* a* b* colorimetry and FTIR spectroscopy before and after aging. Statistical evaluation of the deltaL,* deltaa,* deltab,* deltaE and %deltaRDB data was performed by one-way ANOVA and Tukey's test. The %RDB data before and after aging were statistically analyzed using two-way ANOVA and Student-Newman-Keuls test. In all cases an alpha = 0.05 significance level was used. No statistically significant differences were found in deltaL*, deltaa*, deltaE and %deltaRDB among the materials tested. Tetric Ceram demonstrated a significant difference in deltab*. All the materials showed visually perceptible (deltaE >1) but clinically acceptable values (deltaE statistically significant differences in %RDB were noticed before and after aging (p statistically significantly different among all the groups tested. No correlation was found between deltaE and %deltaRDB.

Ageing Management Review of the reactor pressure vessels in Laguna Verde NPP

International Nuclear Information System (INIS)

Gris Cruz, Magdalena; Arganis, Carlos R.J.; Medina Almazan, A. Liliana

2012-01-01

In the present paper, for both units of Laguna Verde Nuclear Power Plant (LVNPP), the Ageing Management Review of the reactor pressure Vessel was carried out, including the identification of the intended functions, the materials and the environments. The evaluation of the ageing effect/mechanism and the Aging management programs currently implemented were prepared. The most important aging effects/ mechanisms are: loss of fracture toughness due to neutron irradiation embrittlement, fatigue, stress corrosion cracking (SCC), general corrosion and erosion-corrosion. The neutron irradiation embrittlement is managed by the reactor vessel materials surveillance program. The fatigue is a Time Limited Aging Analysis (TLAA), for which is necessary to calculate some fatigue usage factors. SCC is managed by, the In service inspections (ISI) program, but also by the Water Chemistry program, including, currently, On Line Noble Chem. The water chemistry program also manages General Corrosion and erosion-corrosion. The results were compared with the GALL report. (author)

Aging of a copper bearing HSLA-100 steel

Indian Academy of Sciences (India)

The aging process caused a slow transformation of lath martensite into acicular ferrite ... India; School of Physics and Materials Science, Thapar Institute of Engineering and ... Manuscript received: 6 June 2002; Manuscript revised: 1 April 2003 ...

Fracture, aging and disease in bone

Energy Technology Data Exchange (ETDEWEB)

Ager, J.W.; Balooch, G.; Ritchie, R.O.

2006-02-01

From a public health perspective, developing a detailed mechanistic understanding of the well-known increase in fracture risk of human bone with age is essential. This also represents a challenge from materials science and fracture mechanics viewpoints. Bone has a complex, hierarchical structure with characteristic features ranging from nanometer to macroscopic dimensions; it is therefore significantly more complex than most engineering materials. Nevertheless, by examining the micro-/nano-structural changes accompanying the process of aging using appropriate multiscale experimental methods and relating them to fracture mechanics data, it is possible to obtain a quantitative picture of how bone resists fracture. As human cortical bone exhibits rising ex vivo crack-growth resistance with crack extension, its fracture toughness must be evaluated in terms of resistance-curve (R-curve) behavior. While the crack initiation toughness declines with age, the more striking finding is that the crack-growth toughness declines even more significantly and is essentially absent in bone from donors exceeding 85 years in age. To explain such an age-induced deterioration in the toughness of bone, we evaluate its fracture properties at multiple length scales, specifically at the molecular and nanodimensions using pico-force atomic-force microscopy, nanoindentation and vibrational spectroscopies, at the microscale using electron microscopy and hard/soft x-ray computed tomography, and at the macroscale using R-curve measurements. We show that the reduction in crack-growth toughness is associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging, and that this occurs at relatively coarse size-scales in the range of tens to hundreds of micrometers. Finally, we briefly describe how specific clinical treatments, e.g., with steroid hormones to treat various inflammatory conditions, can prematurely damage bone, thereby reducing its

NuPEER Dijon 2005 Symposium. Ageing issues in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Emond, David (ed.) [BCCN, Autorite de Surete Nucleaire, ASN, 6, place du Colonel Bourgoin, 75572 Paris Cedex 12 (France)

2005-07-01

The French Nuclear Safety Authority (ASN) organized an international symposium on regulatory aspects of ageing issues for nuclear pressure equipment. The ageing of nuclear pressure equipment is an issue of growing importance for nuclear regulators and material experts worldwide as age-related degradation of major pressure-retaining components challenges the remaining operating life of nuclear power plants. This symposium aimed at providing a forum for technical exchange among the staffs responsible for nuclear pressure equipment within the safety authorities and the associated expertise organisations. The contents of the symposium is as follows: 1. Control and supervision of safety of nuclear pressure equipment in France and abroad; 1.1. Position of the French Nuclear Safety Authority (1 paper); 1.2. Regulatory practices worldwide (4 papers); 1.3. Licence renewal: Field experience (2 papers); 1.4. Role of international organisations (1 paper); 2. Management of equipment and materials: From design to degradation mechanisms; 2.1. Operation and equipment (4 papers); 2. Evolution of materials (4 papers); 2.3. Fatigue degradation mechanisms (3 papers); 2.4. Contribution of research and development (4 papers); 3. In-service inspection: Evolutions, methods and strategies; 3.1. Methods and evolution (1 paper); 3.2. Qualification of methods (2 papers); 3.3. Surveillance strategies (2 papers); 4. Testimonies and points of view of utilities (3 papers); 5. Ageing issues taken into account in non nuclear fields (2 papers). The symposium began with workshops devoted to: Operation and equipment; Behaviour of materials; Fatigue degradations; Contributions of research and development. The symposium continued with plenary session that addressed the following issues: Control and supervision of safety of nuclear pressure equipment; Role of international organisations; In-service inspection: Objectives, methods and strategies; Point of view of utilities; Technical summary and

Filter-adsorber aging assessment

Energy Technology Data Exchange (ETDEWEB)

Winegardner, W.K. [Pacific Northwest Laboratory, Richland, WA (United States)

1995-02-01

An aging assessment of high-efficiency particulate (HEPA) air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the U.S. Nuclear Regulatory Commission`s (USNRC) Nuclear Plant Aging Research (NPAR) Program. This evaluation of the general process in which characteristics of these two components gradually change with time or use included the compilation of information concerning failure experience, stressors, aging mechanisms and effects, and inspection, surveillance, and monitoring methods (ISMM). Stressors, the agents or stimuli that can produce aging degradation, include heat, radiation, volatile contaminants, and even normal concentrations of aerosol particles and gasses. In an experimental evaluation of degradation in terms of the tensile breaking strength of aged filter media specimens, over forty percent of the samples did not meet specifications for new material. Chemical and physical reactions can gradually embrittle sealants and gaskets as well as filter media. Mechanisms that can lead to impaired adsorber performance are associated with the loss of potentially available active sites as a result of the exposure of the carbon to airborne moisture or volatile organic compounds. Inspection, surveillance, and monitoring methods have been established to observe filter pressure drop buildup, check HEPA filters and adsorbers for bypass, and determine the retention effectiveness of aged carbon. These evaluations of installed filters do not reveal degradation in terms of reduced media strength but that under normal conditions aged media can continue to effectively retain particles. However, this degradation may be important when considering the likelihood of moisture, steam, and higher particle loadings during severe accidents and the fact it is probable that the filters have been in use for an extended period.

Qualification of Electrical Equipment in Nuclear Power Plants - Management of ageing

International Nuclear Information System (INIS)

Spaang, Kjell; Staahl, Gunnar

2013-02-01

The purpose of this report is to describe programs and tools for assessment of accomplished and documented qualification with respect to ageing of electrical equipment and for development of complimentary ageing management programs. In addition to description of complete programs for management of ageing, tools for validation of the status with regard to ageing of installed ('old') equipment and, where needed, for complementation of their qualification are also included. The report is restricted to safety related equipment containing ageing sensitive parts, mainly organic materials. To this category belong cables and cable joints and a number of equipment containing oils, seals (o-rings), etc. For equipment located in the containment, the possibilities of continuous supervision are limited. The accessibility for regular inspections is also limited in many cases. The main part of this report deals with the qualification of such equipment. Some safety related equipment outside the containment can be located in areas where they are subjected to high temperature and other excessive environmental stresses during normal operation and in areas affected by an accident. Therefore, some material is given also on qualification of equipment located outside containment with better possibilities for frequent inspection and supervision. Part 1 of the report is an executive summary with a general review of the methodologies and their application. The more detailed description of the programs and underlying material, useful data, etc. is given in Part 2

Using failure mode and effect analysis in identification of components sensitive to ageing

International Nuclear Information System (INIS)

Nitoi, Mirela; Turcu, Ilie; Apostol, Minodora; Farcasiu, Mita; Popa, Adrian; Florescu, Gheorghe; Pavelescu, Margarit

2008-01-01

Ageing represents a phenomenon of concern since any degradation that may occur in time could lower a component performance and so reduce its reliability. If the phenomenon is left unchecked and unmitigated, the ageing could increase the risk associated with the facility operation. To understand the ageing degradation of a component, it is first necessary to identify and understand the ageing processes. Since these processes involve constituent materials, parts and the service conditions of components, it is necessary to know the design, materials, service conditions, performance requirements, operating experience (operation, surveillance and maintenance histories) and relevant research results for the component of interest. The purpose of the Ageing Failure Mode and Effect Analysis (AFMEA) is to study the results or effects of item failure caused by ageing, on system operation and to classify each potential failure according to its severity The paper will present the advantages of using AFMEA in identification of most sensitive to ageing components, as the results obtained for a particular case. For each component analyzed, the stressors will be established, the corresponding ageing mechanisms will be identified, as the failure modes induced by the ageing mechanisms. (authors)

Evaluation of aging degradation of structural components

International Nuclear Information System (INIS)

Chopra, O.K.; Shack, W.J.

1992-03-01

Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at 8 n/cm 2 ·s at the low operating temperature of the Shippingport NST, i.e., 55 degrees C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J IC of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of ∼15 y

Aging management assessment of type B transportation packages

International Nuclear Information System (INIS)

Sullivan, G.J.; Stahmer, U.; Freeman, E.L.

2004-01-01

The condition of a physical system such as a radioactive materials transportation package can change as it ages. The degree to which aging effects are identified, prevented or mitigated will depend on the types of inspections and maintenance performed on the critical components of the system. Routine inspections and maintenance may not address degradation mechanisms that are difficult to observe and can act over long periods of time. Aging management is a systematic effort to ensure that the system performs as designed over its entire service life and that degradation mechanisms do not prematurely end the service life. The Nuclear Waste Management Division (NWMD) of Ontario Power Generation (OPG) has developed an Aging Management Procedure and began performing aging management assessments on its Type B(U) packages. This paper discusses the Procedure and briefly describes the aging management assessment performed on the Roadrunner Transportation Package to demonstrate a practical application of the aging management process

Potential Applications of Smart Multifunctional Wearable Materials to Gerontology.

Science.gov (United States)

Armstrong, David G; Najafi, Bijan; Shahinpoor, Mohsen

2017-01-01

Smart multifunctional materials can play a constructive role in addressing some very important aging-related issues. Aging affects the ability of older adults to continue to live safely and economically in their own residences for as long as possible. Thus, there will be a greater need for preventive, acute, rehabilitative, and long-term health care services for older adults as well as a need for tools to enable them to function independently during daily activities. The objective of this paper is, thus, to present a comprehensive review of some potential smart materials and their areas of applications to gerontology. Thus, brief descriptions of various currently available multifunctional smart materials and their possible applications to aging-related problems are presented. It is concluded that some of the most important applications to geriatrics may be in various sensing scenarios to collect health-related feedback or information and provide personalized care. Further described are the applications of wearable technologies to aging-related needs, including devices for home rehabilitation, remote monitoring, social well-being, frailty monitoring, monitoring of diabetes and wound healing and fall detection or prediction. It is also concluded that wearable technologies, when combined with an appropriate application and with appropriate feedback, may help improve activities and functions of older patients with chronic diseases. Finally, it is noted that methods developed to measure what one collectively manages in this population may provide a foundation to establish new definitions of quality of life. © 2017 S. Karger AG, Basel.

Material Stream Strategy for Lithium and Inorganics (U)

Energy Technology Data Exchange (ETDEWEB)

Safarik, Douglas Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dunn, Paul Stanton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Korzekwa, Deniece Rochelle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2018-01-24

Design Agency Responsibilities: Manufacturing Support to meet Stockpile Stewardship goals for maintaining the nuclear stockpile through experimental and predictive modeling capability. Development and maintenance of Manufacturing Science expertise to assess material specifications and performance boundaries, and their relationship to processing parameters. Production Engineering Evaluations with competence in design requirements, material specifications, and manufacturing controls. Maintenance and enhancement of Aging Science expertise to support Stockpile Stewardship predictive science capability.

Age hardening of cold-worked Zr-2.5 wt% Nb pressure tube alloy

International Nuclear Information System (INIS)

Kishore, R.; Singh, R.N.; Dey, G.K.; Sinha, T.K.

1992-01-01

Specimens for hardness and tensile tests, machined from a cold-worked zirconium-2.5% niobium pressure tube, with their axes parallel to longitudinal and transverse directions, were aged for 1 hr. at 300-500 C. The age hardening behaviour was monitored by mechanical tests, electron-microscopy and x-ray diffraction. In addition a few studies were carried on longitudinal tension specimens subjected to prolonged ageing (100-1000 hrs) at 300 C. It was observed that the short-term (1 hour) thermal ageing of this material at 300-400 C caused an increase in both strength and hardness without affecting ductility. It appears that the observed age-hardening is due to precipitation hardening by a niobium-rich phase and softening by recovery of cold-work and that the phenomenon is influenced by crystallographic texture. Further it was noted that a prolonged ageing at 300 C upto 1000 hrs, did not cause any appreciable changes in strength and ductility of the material compared to those obtained by 1 hour ageing at the same temperature. (author). 11 refs., 3 figs., 2 tabs

Early diagnosis of junior school age children’s posture disorders

OpenAIRE

N.S. Razumeiko

2015-01-01

Purpose: to describe specificities of early diagnosis method for junior school age children’s posture disorders. Material: in pedagogic experiment 156 junior school age children (boys and girls of 7-10 years’ age) participated. All children had no experience of training in sport circles. For determination of uniformity of the tested we fulfilled experts’ examination for presence or absence of external signs of posture disorders in frontal plane. The children’s examination was conducted by qua...

Science, technology and the 'grand challenge' of aging

DEFF Research Database (Denmark)

Jæger, Birgit; Peine, Alexander; Moors, Ellen

2015-01-01

In this paper, we introduce the themes addressed and the approaches used in this special issue. We start by briefly discussing the state of the art in research and policy making related to science, technology and ageing. We argue that an important gap characterizes this state of the art: current...... approaches do not consider material practice and materiality to be an inherent part of later life as constituted in contemporary societies. Science and Technology Studies (STS) provide both the theories and methods to address this gap, and thus deploy a theoretical and empirical understanding of science......, technology and ageing that captures how later life co-evolves with the practices of technology use and design. We briefly discuss how the articles in the collection each contribute to such an understanding across various locations. We conclude that, together, the contributions specify a perspective...

Nuclear Plant Aging Research (NPAR) program plan

International Nuclear Information System (INIS)

1985-07-01

The nuclear plant aging research described in this plan is intended to resolve issues related to the aging and service wear of equipment and systems at commercial reactor facilities and their possible impact on plant safety. Emphasis has been placed on identification and characterization of the mechansims of material and component degradation during service and evaluation of methods of inspection, surveillance, condition monitoring and maintenance as means of mitigating such effects. Specifically the goals of the program are as follows: (1) to identify and characterize aging and service wear effects which, if unchecked, could cause degradation of structures, components, and systems and thereby impair plant safety; (2) to identify methods of inspection, surveillance and monitoring, or of evaluating residual life of structures, components, and systems, which will assure timely detection of significant aging effects prior to loss of safety function; and (3) to evaluate the effectiveness of storage, maintenance, repair and replacement practices in mitigating the rate and extent of degradation caused by aging and service wear

An Investigation of Materialism and Life Satisfaction

Directory of Open Access Journals (Sweden)

Afreen Faiza

2017-12-01

Full Text Available The collectivistic culture of Pakistan is perforating with hedonic, modern and lavishing values. People are becoming more concerned with material aspirations and accumulation of wealth. The aim of present study is to investigate the relationship between materialism and life satisfaction among Pakistani individuals. A sample of (N=104 Muslim individuals were recruited through random sampling technique from different areas of Karachi city. Their age ranged from 16-46 years (M= 1.60, S.D=.854. The individuals were administered Richins Material values scale (2004 and Diener et al. the Satisfaction with Life Scale (1985. A significant positive relationship was obtained between materialism and life satisfaction (r=.273, p< .01. The future implementation of strategies for promotion of wellbeing of Pakistani individuals is discussed in the light of findings of present study.

Modeling Manufacturing Impacts on Aging and Reliability of Polyurethane Foams

Energy Technology Data Exchange (ETDEWEB)

Rao, Rekha R.; Roberts, Christine Cardinal; Mondy, Lisa Ann; Soehnel, Melissa Marie; Johnson, Kyle; Lorenzo, Henry T.

2016-10-01

Polyurethane is a complex multiphase material that evolves from a viscous liquid to a system of percolating bubbles, which are created via a CO2 generating reaction. The continuous phase polymerizes to a solid during the foaming process generating heat. Foams introduced into a mold increase their volume up to tenfold, and the dynamics of the expansion process may lead to voids and will produce gradients in density and degree of polymerization. These inhomogeneities can lead to structural stability issues upon aging. For instance, structural components in weapon systems have been shown to change shape as they age depending on their molding history, which can threaten critical tolerances. The purpose of this project is to develop a Cradle-to-Grave multiphysics model, which allows us to predict the material properties of foam from its birth through aging in the stockpile, where its dimensional stability is important.

Progression of aging in Mexico: the Mexican Health and Aging Study (MHAS) 2012

Science.gov (United States)

Wong, Rebeca; Michaels-Obregón, Alejandra; Palloni, Alberto; Gutiérrez-Robledo, Luis Miguel; González-González, César; López-Ortega, Mariana; Téllez-Rojo, Martha María; Mendoza-Alvarado, Laura Rosario

2015-01-01

Objective To describe the third wave of the Mexican Health and Aging Study (MHAS), completed in 2012, and present preliminary results. Materials and methods Descriptive analyses by gender and age group of demographic and socioeconomic characteristics, health conditions and health behaviors, as well as social support and life satisfaction measures are presented. In addition, external validations are presented by comparing MHAS 2012 indicators with other national data sources. Results For the panel of older adults in the sample, the rate of health care insurance coverage increased greatly between 2001 and 2012, a significantly higher change in rural compared to urban areas. The results for 2012 are consistent with the previous two waves for the main indicators of health and physical disability prevalence, risk factors, and behaviors. Conclusions The MHAS offers a unique opportunity to study aging in Mexico, as well as to complete cross-national comparisons. The cumulative number of deaths in the cohort should support the study of mortality and its association with health outcomes and behaviors over the life cycle. In addition, the sub-samples of objective markers will enable methodological research on self-reports and associations of biomarkers in old age with similar health outcomes and behaviors. PMID:26172238

Aging and experience in the recognition of musical transpositions.

Science.gov (United States)

Halpern, A R; Bartlett, J C; Dowling, W J

1995-09-01

The authors examined the effects of age, musical experience, and characteristics of musical stimuli on a melodic short-term memory task in which participants had to recognize whether a tune was an exact transposition of another tune recently presented. Participants were musicians and nonmusicians between ages 18 and 30 or 60 and 80. In 4 experiments, the authors found that age and experience affected different aspects of the task, with experience becoming more influential when interference was provided during the task. Age and experience interacted only weakly, and neither age nor experience influenced the superiority of tonal over atonal materials. Recognition memory for the sequences did not reflect the same pattern of results as the transposition task. The implications of these results for theories of aging, experience, and music cognition are discussed.

Evaluation of aging and hydration in natural volcanic glass: magnetic property variations during artificial aging and hydration experiments

Science.gov (United States)

Bowles, J. A.; Patiman, A.

2017-12-01

The recorded geomagnetic field intensity is a function of magnetic mineralogy, grain size, and mineral concentration as well as material stability in nature and during laboratory experiments. Fresh, unhydrated, volcanic glasses are recognized as a nearly ideal natural material for use in paleointensity experiments because they contain the requisite single domain to pseudo-single-domain magnetic particles. Although alteration of magnetic mineralogy can be monitored during the experiments, it is unclear how mineralogy and hence magnetization might change with age as the metastable glass structure relaxes and/or the glass becomes hydrated. Bulk magnetic properties as a function of age show no clear trend, even over hundreds of millions of years. This may be due to the fact that even in fresh, unhydrated glass, there are small-scale differences in magnetic properties due to variation cooling rate or composition variations. Therefore, in order to better understand how magnetic mineralogy evolves with time and hydration, we conducted artificial aging and hydration experiments on fresh, unhydrated rhyolitic (South Deadman Creek, California, 650-yr) and basaltic (Axial Seamount, 2011) end-member glasses. Here, we present the results of artificial aging and hydration experiments. Elevated temperatures accelerate the glass relaxation process in a way that relaxation time decreases with increasing temperature. Aged samples are dry-annealed at 200, 300 and 400 °C for up to 240 days. A second set of samples are hydrated under pressure at 300°C and 450°C. In all cases, isothermal remanent magnetization (IRM) acquisition is monitored to assess changes in the coercivity spectrum and saturation IRM. Preliminary aging results show that in basaltic and rhyolitic glass there is one main peak coercivity at 150 mT and 35 mT, respectively. An increasing sIRM and decreasing peak coercivity trend is observed in basaltic glass whereas no trend is shown in the rhyolitic glass in both

Aging effects on oil-contaminated Kuwaiti sand

International Nuclear Information System (INIS)

Al-Sanad, H.A.; Ismael, N.F.

1997-01-01

Large quantities of oil-contaminated sands resulted from the destruction of oil wells and the formation of oil lakes in Kuwait at the end of the Gulf Wa/r. A laboratory testing program was carried out to determine the geotechnical properties of this material and the effect of aging on their properties. Tests included direct shear, triaxial, and consolidation tests on clean and contaminated sand at the same relative density. The influence of aging was examined by testing uncontaminated sand after aging for one, three, and six months in natural environmental conditions. The results indicated increased strength and stiffness due to aging and a reduction of the oil content due to evaporation of volatile compounds. The factors that influence the depth of oil penetration in compacted sand columns were also examined including the type of oil, relative density, and the amount of fines

Accelerated aging, natural aging, and small punch testing of gamma-air sterilized polycarbonate urethane acetabular components.

Science.gov (United States)

Kurtz, S M; Siskey, R; Reitman, M

2010-05-01

The objectives of this study were three-fold: (1) to determine the applicability of the small punch test to characterize Bionate 80A polycarbonate urethane (PCU) acetabular implants; (2) to evaluate the susceptibility of PCU acetabular implants to exhibit degradation of mechanical behavior following gamma irradiation in air and accelerated aging; and (3) to compare the oxidation of gamma-air sterilized PCU following accelerated aging and 5 years of natural shelf aging. In addition to attenuated total reflectance-Fourier transform infrared spectroscopy, we also adapted a miniature specimen mechanical test, the small punch test, for the deformable PCU cups. Accelerated aging was performed using ASTM F2003, a standard test that represents a severe oxidative challenge. The results of this study suggest that the small punch test is sufficiently sensitive and reproducible to discriminate slight differences in the large-deformation mechanical behavior of Bionate 80A following accelerated aging. The gamma-air sterilized PCU had a reduction of 9% in ultimate load after aging. Five years of shelf aging had little effect on the mechanical properties of the PCU. Overall, our findings suggest that the Bionate 80A material has greater oxidative stability than ultra-high molecular weight polyethylene following gamma irradiation in air and exposure to a severe oxidative challenge. (c) 2010 Wiley Periodicals, Inc.

Creep property testing of energy power plant component material

International Nuclear Information System (INIS)

Nitiswati, Sri; Histori; Triyadi, Ari; Haryanto, Mudi

1999-01-01

Creep testing of SA213 T12 boiler piping material from fossil plant, Suralaya has been done. The aim of the testing is to know the creep behaviour of SA213 T12 boiler piping material which has been used more than 10 yeas, what is the material still followed ideal creep curve (there are primary stage, secondary stage, and tertiary stage). This possibility could happened because the material which has been used more than 10 years usually will be through ageing process because corrosion. The testing was conducted in 520 0C, with variety load between 4% until 50% maximum allowable load based on strength of the material in 520 0C

Integrative Microbiology – The Third Golden Age Reflections

Indian Academy of Sciences (India)

Administrator

and Tufts University School of Medicine, Boston, MA 02111, USA. .... about the mechanisms that control gene expression in bacteria. How is the synthesis of .... The second Golden Age of microbiology materialized in the 1940's with the birth of.

An update on the Structural Aging Program

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.; Mori, Y.; Arndt, E.G.

1992-01-01

The Structural Aging (SAG) Program is being conducted at the Oak Ridge National Laboratory (ORNL) for the Nuclear Regulatory Commission (NRC). The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. The program is organized into four tasks: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for Continued Service Determinations. Objectives and a summary of accomplishments under each of these tasks are presented

Packaging material and aluminum. Hoso zairyo to aluminum

Energy Technology Data Exchange (ETDEWEB)

Itaya, T [Mitsubishi Aluminum Co. Ltd., Tokyo (Japan)

1992-02-01

The present paper introduces aluminum foil packaging materials among the relation between packing materials and aluminum. The characteristics of aluminum foil in the packaging area are in its barrier performance, non-toxicity, tastelessness and odorlessness. Its excellent functions and processibility suit best as functional materials for food, medicine and industrial material packaging. While an aluminum foil may be used as a single packing material as in foils used in homes, many of it as a packaging material are used in combination with adhesives, papers or plastic films, or coated or printed. It is used as composite materials laminated or coated with other materials according to their use for the purpose of complementing the aluminum foil as the base material. Representative method to laminate aluminum foils include the wet lamination, dry lamination, thermally dissolved lamination and extruded lamination. The most important quality requirement in lamination is the adhesion strength, which requires a close attention in selecting the kinds of adhesive, laminating conditions, and aging conditions. 8 figs., 6 tabs.

Compendium of information on identification and testing of materials for plastic solar thermal collectors

Energy Technology Data Exchange (ETDEWEB)

McGinniss, V.D.; Sliemers, F.A.; Landstrom, D.K.; Talbert, S.G.

1980-07-31

This report is intended to organize and summarize prior and current literature concerning the weathering, aging, durability, degradation, and testing methodologies as applied to materials for plastic solar thermal collectors. Topics covered include (1) rate of aging of polymeric materials; (2) environmental factors affecting performance; (3) evaluation and prediction of service life; (4) measurement of physical and chemical properties; (5) discussion of evaluation techniques and specific instrumentation; (6) degradation reactions and mechanisms; (7) weathering of specific polymeric materials; and (8) exposure testing methodology. Major emphasis has been placed on defining the current state of the art in plastics degradation and on identifying information that can be utilized in applying appropriate and effective aging tests for use in projecting service life of plastic solar thermal collectors. This information will also be of value where polymeric components are utilized in the construction of conventional solar collectors or any application where plastic degradation and weathering are prime factors in material selection.

Overview of synergistic aging effects

International Nuclear Information System (INIS)

Steigelmann, W.; Farber, M.

1982-01-01

Proper, technically defensible qualification of materials and equipment for nuclear power facilities requires that the effects of combined environment exposures be addressed. The full significance of synergistic effects resulting from combined stresses still remains largely an unknown to be provided for by use of conservatisms, allowing a sizeable margin in test programs and analyses to account for possible combined effects. However, these margins, when applied to sequential aging tests, may under- or over-estimate the qualified life of the material or equipment. Experimentation with radiation dose-rate effects, simultaneous vs. sequential ordered exposures, and other combined environment testing are highlighted in this paper to provide an overview of the current state-of-knowledge concerning synergistic effects and their significance to qualification programs

Construction of computational program of aging in insulating materials for searching reversed sequential test conditions to give damage equivalent to simultaneous exposure of heat and radiation

International Nuclear Information System (INIS)

Fuse, Norikazu; Homma, Hiroya; Okamoto, Tatsuki

2013-01-01

Two consecutive numerical calculations on degradation of polymeric insulations under thermal and radiation environment are carried out to simulate so-called reversal sequential acceleration test. The aim of the calculation is to search testing conditions which provide material damage equivalent to the case of simultaneous exposure of heat and radiation. At least following four parameters are needed to be considered in the sequential method; dose rate and exposure time in radiation, as well as temperature and aging time in heating. The present paper discusses the handling of these parameters and shows some trial calculation results. (author)

Curcumin-functionalized silk biomaterials for anti-aging utility.

Science.gov (United States)

Yang, Lei; Zheng, Zhaozhu; Qian, Cheng; Wu, Jianbing; Liu, Yawen; Guo, Shaozhe; Li, Gang; Liu, Meng; Wang, Xiaoqin; Kaplan, David L

2017-06-15

Curcumin is a natural antioxidant that is isolated from turmeric (Curcuma longa) and exhibits strong free radical scavenging activity, thus functional for anti-aging. However, poor stability and low solubility of curcumin in aqueous conditions limit its biomedical applications. Previous studies have shown that the anti-oxidation activity of curcumin embedded in silk fibroin films could be well preserved, resulting in the promoted adipogenesis from human mesenchymal stem cells (hMSCs) cultured on the surface of the films. In the present study, curcumin was encapsulated in both silk fibroin films (silk/cur films) and nanoparticles (silk/cur NPs), and their anti-aging effects were compared with free curcumin in solution, with an aim to elucidate the mechanism of anti-aging of silk-associated curcumin and to better serve biomedical applications in the future. The morphology and structure of silk/cur film and silk/cur NP were characterized using SEM, FTIR and DSC, indicating characteristic stable beta-sheet structure formation in the materials. Strong binding of curcumin molecules to the beta-sheet domains of silk fibroin resulted in the slow release of curcumin with well-preserved activity from the materials. For cell aging studies, rat bone marrow mesenchymal stem cells (rBMSCs) were cultured in the presence of free curcumin (FC), silk/cur film and silk/cur NP, and cell proliferation and markers of aging (P53, P16, HSP70 gene expression and β-Galactosidase activity) were examined. The results indicated that cell aging was retarded in all FC, silk/cur NP and silk/cur film samples, with the silk-associated curcumin superior to the FC. Copyright © 2017 Elsevier Inc. All rights reserved.

Lattice Modeling of Early-Age Behavior of Structural Concrete

OpenAIRE

Pan, Yaming; Prado, Armando; Porras, Roc?o; Hafez, Omar M.; Bolander, John E.

2017-01-01

The susceptibility of structural concrete to early-age cracking depends on material composition, methods of processing, structural boundary conditions, and a variety of environmental factors. Computational modeling offers a means for identifying primary factors and strategies for reducing cracking potential. Herein, lattice models are shown to be adept at simulating the thermal-hygral-mechanical phenomena that influence early-age cracking. In particular, this paper presents a lattice-based ap...

PENERAPAN MATERIAL KACA DALAM ARSITEKTUR

Directory of Open Access Journals (Sweden)

Lestari .

2014-07-01

Full Text Available Kaca telah dikenal sejak ribuan tahun dan merupakan bahan buatan manusia yang cukup tua. Penggunaannya sebagai bahan bangunan meluas sejak abad ke 17 terutama setelah perang dunia kedua.  Arsitektur kaca menjadi suatu kecenderungan dari desain-desain bangunan di dunia sejak abad ke-20. Material ini dianggap sangat relevan dengan konsep-konsep yang ada. Kaca digunakan sebagai material ornamen, bukaan atau jendela, material kulit  bangunan,  sampai pada material struktur  bangunan. Sifat kaca yang transparan,  simple, dan bersih menjadikan material ini menguntungkan untuk mendukung konsep yang digunakan. Tulisan ini memaparkan penggunaan kaca sebagai bahan bangunan, baik sebagai bahan ornamen, kulit bangunan atau struktur bangunan, maupun sebagai pendukung konsep arsitektur khususnya konsep transparansi. Dipaparkan pula mengenai sifat-sifat teknis dari bahan kaca sebagai pertimbangan dalam pemilihan bahan bangunan.   Glass has been known for thousands of years and is a man made material  that is quite old. Extends its use as building material since the 17 century, especially after the second world war. Glass architecture become a trend of buiding designs in the world since 20th century. This material relevant to the existing concepts. Glass is used as an ornament material, window, the building skin materials, and the building structure materials. Glass  properties that transparent, simple and clean make this material support the concepts used. This paper describes the use of glass as a building material, either as a ornament, the building skins, the building structures, and the building concepts expecially transparency concept. This paper also present the technical properties of glass as a building material REFERENCES Garg, N.K . 2007. Guidelines for Use of Glass in Building. New age international publisher. New Delhi Piano, R. 1997. The Renzo Piano Logbook. The Monacelli Press. London Staib, Schittich. 1999. Glass Construction

More Materiales Tocante Los Latinos. A Bibliography of Materials on the Spanish-American.

Science.gov (United States)

Harrigan, Joan, Comp.

A bibliography of materials published between 1964 and 1969 on the Spanish American is presented to assist librarians and educators in locating Hispano instructional aids. Over 120 annotated entries list audio-visual aids and reading materials for students of all ages, professional materials for educators including librarians, ERIC materials…

Human factors: a major issue in plant aging

International Nuclear Information System (INIS)

Widrig, R.D.

1985-07-01

Human factors issues will be of great significance in the safe and reliable operation of aging nuclear power plants, and they may be more important than materials/component-type issues. Human actions can accelerate or decelerate te physical aging process. And an aging plant can have significant negative implications on staff performance and actions. Some examples include difficulties in attracting and retaining good managers, financial decisions based on a short and uncertain remaining plant life, difficulties in replacing retiring staff, increased maintenance complexity, and increased burden on training. These problems can be dealt with more effectively by early recognition and a well conceived mitigation effort

Effect of Thermal Aging and Test Temperatures on Fracture Toughness of SS 316(N) Welds

Science.gov (United States)

Dutt, B. Shashank; Babu, M. Nani; Shanthi, G.; Moitra, A.; Sasikala, G.

2018-03-01

The effect of thermal aging and test temperatures on fracture toughness (J 0.2) of SS 316(N) weld material has been studied based on J-R curve evaluations. The aging of the welds was carried out at temperatures 370, 475 and 550 °C and for durations varying from 1000 to 20,000 h. The fracture toughness (J-R curve) tests were carried out at 380 and 550 °C for specimens after all aging conditions, including as-weld condition. The initiation fracture toughness (J 0.2) of the SS 316(N) weld material has shown degradation after 20,000-h aging durations and is reflected in all the test temperatures and aging temperatures. The fracture toughness after different aging conditions and test temperatures, including as-weld condition, was higher than the minimum specified value for this class of welds.

Method and apparatus for the management of hazardous waste material

Science.gov (United States)

Murray, Jr., Holt

1995-01-01

A container for storing hazardous waste material, particularly radioactive waste material, consists of a cylindrical body and lid of precipitation hardened C17510 beryllium-copper alloy, and a channel formed between the mated lid and body for receiving weld filler material of C17200 copper-beryllium alloy. The weld filler material has a precipitation hardening temperature lower than the aging kinetic temperature of the material of the body and lid, whereby the weld filler material is post weld heat treated for obtaining a weld having substantially the same physical, thermal, and electrical characteristics as the material of the body and lid. A mechanical seal assembly is located between an interior shoulder of the body and the bottom of the lid for providing a vacuum seal.

Phase-change materials for non-volatile memory devices: from technological challenges to materials science issues

Science.gov (United States)

Noé, Pierre; Vallée, Christophe; Hippert, Françoise; Fillot, Frédéric; Raty, Jean-Yves

2018-01-01

Chalcogenide phase-change materials (PCMs), such as Ge-Sb-Te alloys, have shown outstanding properties, which has led to their successful use for a long time in optical memories (DVDs) and, recently, in non-volatile resistive memories. The latter, known as PCM memories or phase-change random access memories (PCRAMs), are the most promising candidates among emerging non-volatile memory (NVM) technologies to replace the current FLASH memories at CMOS technology nodes under 28 nm. Chalcogenide PCMs exhibit fast and reversible phase transformations between crystalline and amorphous states with very different transport and optical properties leading to a unique set of features for PCRAMs, such as fast programming, good cyclability, high scalability, multi-level storage capability, and good data retention. Nevertheless, PCM memory technology has to overcome several challenges to definitively invade the NVM market. In this review paper, we examine the main technological challenges that PCM memory technology must face and we illustrate how new memory architecture, innovative deposition methods, and PCM composition optimization can contribute to further improvements of this technology. In particular, we examine how to lower the programming currents and increase data retention. Scaling down PCM memories for large-scale integration means the incorporation of the PCM into more and more confined structures and raises materials science issues in order to understand interface and size effects on crystallization. Other materials science issues are related to the stability and ageing of the amorphous state of PCMs. The stability of the amorphous phase, which determines data retention in memory devices, can be increased by doping the PCM. Ageing of the amorphous phase leads to a large increase of the resistivity with time (resistance drift), which has up to now hindered the development of ultra-high multi-level storage devices. A review of the current understanding of all these

Component Degradation Susceptibilities As The Bases For Modeling Reactor Aging Risk

International Nuclear Information System (INIS)

Unwin, Stephen D.; Lowry, Peter P.; Toyooka, Michael Y.

2010-01-01

The extension of nuclear power plant operating licenses beyond 60 years in the United States will be necessary if we are to meet national energy needs while addressing the issues of carbon and climate. Characterizing the operating risks associated with aging reactors is problematic because the principal tool for risk-informed decision-making, Probabilistic Risk Assessment (PRA), is not ideally-suited to addressing aging systems. The components most likely to drive risk in an aging reactor - the passives - receive limited treatment in PRA, and furthermore, standard PRA methods are based on the assumption of stationary failure rates: a condition unlikely to be met in an aging system. A critical barrier to modeling passives aging on the wide scale required for a PRA is that there is seldom sufficient field data to populate parametric failure models, and nor is there the availability of practical physics models to predict out-year component reliability. The methodology described here circumvents some of these data and modeling needs by using materials degradation metrics, integrated with conventional PRA models, to produce risk importance measures for specific aging mechanisms and component types. We suggest that these measures have multiple applications, from the risk-screening of components to the prioritization of materials research.

Condition Assessment of Kevlar Composite Materials Using Raman Spectroscopy

Science.gov (United States)

Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

2007-01-01

This viewgraph presentation includes the following main concepts. Goal: To evaluate Raman spectroscopy as a potential NDE tool for the detection of stress rupture in Kevlar. Objective: Test a series of strand samples that have been aged under various conditions and evaluate differences and trends in the Raman response. Hypothesis: Reduction in strength associated with stress rupture may manifest from changes in the polymer at a molecular level. If so, than these changes may effect the vibrational characteristics of the material, and consequently the Raman spectra produced from the material. Problem Statement: Kevlar composite over-wrapped pressure vessels (COPVs) on the space shuttles are greater than 25 years old. Stress rupture phenomena is not well understood for COPVs. Other COPVs are planned for hydrogen-fueled vehicles using Carbon composite material. Raman spectroscopy is being explored as an non-destructive evaluation (NDE) technique to predict the onset of stress rupture in Kevlar composite materials. Test aged Kevlar strands to discover trends in the Raman response. Strength reduction in Kevlar polymer will manifest itself on the Raman spectra. Conclusions: Raman spectroscopy has shown relative changes in the intensity and FWHM of the 1613 cm(exp -1) peak. Reduction in relative intensity for creep, fleet leader, and SIM specimens compared to the virgin strands. Increase in FWHM has been observed for the creep and fleet leader specimens compared to the virgin strands. Changes in the Raman spectra may result from redistributing loads within the material due to the disruption of hydrogen bonding between crystallites or defects in the crystallites from aging the Kevlar strands. Peak shifting has not been observed to date. Analysis is ongoing. Stress measurements may provide a tool in the short term.

Efficient Workflows for Curation of Heterogeneous Data Supporting Modeling of U-Nb Alloy Aging

International Nuclear Information System (INIS)

Ward, Logan Timothy; Hackenberg, Robert Errol

2016-01-01

These are slides from a presentation summarizing a graduate research associate's summer project. The following topics are covered in these slides: data challenges in materials, aging in U-Nb Alloys, Building an Aging Model, Different Phase Trans. in U-Nb, the Challenge, Storing Materials Data, Example Data Source, Organizing Data: What is a Schema?, What does a 'XML Schema' look like?, Our Data Schema: Nice and Simple, Storing Data: Materials Data Curation System (MDCS), Problem with MDCS: Slow Data Entry, Getting Literature into MDCS, Staging Data in Excel Document, Final Result: MDCS Records, Analyzing Image Data, Process for Making TTT Diagram, Bottleneck Number 1: Image Analysis, Fitting a TTP Boundary, Fitting a TTP Curve: Comparable Results, How Does it Compare to Our Data?, Image Analysis Workflow, Curating Hardness Records, Hardness Data: Two Key Decisions, Before Peak Age? - Automation, Interactive Viz, Which Transformation?, Microstructure-Informed Model, Tracking the Entire Process, General Problem with Property Models, Pinyon: Toolkit for Managing Model Creation, Tracking Individual Decisions, Jupyter: Docs and Code in One File, Hardness Analysis Workflow, Workflow for Aging Models, and conclusions.

Efficient Workflows for Curation of Heterogeneous Data Supporting Modeling of U-Nb Alloy Aging

Energy Technology Data Exchange (ETDEWEB)

Ward, Logan Timothy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hackenberg, Robert Errol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-08-31

These are slides from a presentation summarizing a graduate research associate's summer project. The following topics are covered in these slides: data challenges in materials, aging in U-Nb Alloys, Building an Aging Model, Different Phase Trans. in U-Nb, the Challenge, Storing Materials Data, Example Data Source, Organizing Data: What is a Schema?, What does a "XML Schema" look like?, Our Data Schema: Nice and Simple, Storing Data: Materials Data Curation System (MDCS), Problem with MDCS: Slow Data Entry, Getting Literature into MDCS, Staging Data in Excel Document, Final Result: MDCS Records, Analyzing Image Data, Process for Making TTT Diagram, Bottleneck Number 1: Image Analysis, Fitting a TTP Boundary, Fitting a TTP Curve: Comparable Results, How Does it Compare to Our Data?, Image Analysis Workflow, Curating Hardness Records, Hardness Data: Two Key Decisions, Before Peak Age? - Automation, Interactive Viz, Which Transformation?, Microstructure-Informed Model, Tracking the Entire Process, General Problem with Property Models, Pinyon: Toolkit for Managing Model Creation, Tracking Individual Decisions, Jupyter: Docs and Code in One File, Hardness Analysis Workflow, Workflow for Aging Models, and conclusions.

Biomimetic materials for controlling bone cell responses.

Science.gov (United States)

Drevelle, Olivier; Faucheux, Nathalie

2013-01-01

Bone defects that cannot "heal spontaneously during life" will become an ever greater health problem as populations age. Harvesting autografts has several drawbacks, such as pain and morbidity at both donor and acceptor sites, the limited quantity of material available, and frequently its inappropriate shape. Researchers have therefore developed alternative strategies that involve biomaterials to fill bone defects. These biomaterials must be biocompatible and interact with the surrounding bone tissue to allow their colonization by bone cells and blood vessels. The latest generation biomaterials are not inert; they control cell responses like adhesion, proliferation and differentiation. These biomaterials are called biomimetic materials. This review focuses on the development of third generation materials. We first briefly describe the bone tissue with its cells and matrix, and then how bone cells interact with the extracellular matrix. The next section covers the materials currently used to repair bone defects. Finally, we describe the strategies employed to modify the surface of materials, such as coating with hydroxyapatite and grafting biomolecules.

Effectiveness of storage practices in mitigating aging degradation during reactor layup

International Nuclear Information System (INIS)

Enderlin, W.I.

1995-09-01

One of the issues identified in the US Nuclear Regulatory Commission's Nuclear Plant Aging Research program plan is the need to understand the state of ''mothballed'' or other out-of-service equipment to ensure subsequent safe operation. Programs for proper storage and preservation of materials and components are required by NRC regulations (10 CFR 50, Appendix B). However, materials and components have been seriously degraded due to improper storage, protection, or layup, at facilities under construction as well as those with operating licenses. Pacific Northwest Laboratory has evaluated management of aging for unstarted or mothballed nuclear power plants. The investigations revealed that no uniform guidance in the industry addresses reactor layup. In each case investigated, layup was not initiated in a timely manner, primarily because of schedule uncertainty. Hence, it is reasonable to assume that this delay resulted in accelerated aging of some safety-significant structures, systems, and components (SSCs). The applicable layup process is site-specific. The reactor type, climatic setting, operational status, and materials of construction are factors that strongly dictate the layup method to be used. The adequacy of current layup practices, and hence their impact on safety-significant SSCS, is not fully understood

Project GRETE: evaluation of non destructive testing techniques for monitoring of material degradation

International Nuclear Information System (INIS)

Coste, J.F.

2001-01-01

The material aging of major critical components of nuclear installations due to in-service conditions may lead to a degradation of their mechanical characteristics. The early detection of material changes and their monitoring using innovative non destructive testing techniques would allow to plan actions in order to prevent the apparition of macroscopic damage (e.g. cracks). One major difficulty in using these particular techniques is to correlate the changes in the measured NDT signals to the microstructural changes in the material due to aging. This problem may be solved through careful microstructural examinations of the material damage. The objective of the project GRETE is to illustrate the potential use of NDT techniques for the monitoring of material degradation through two examples: neutron irradiation of reactor pressure vessel steel and thermal fatigue of piping. The purpose of this paper is to present the project and its programme of work. (author)

The Management of Visibilities in the Digital Age

DEFF Research Database (Denmark)

Flyverbom, Mikkel; Leonardi, Paul; Stohl, Cynthia

2016-01-01

What we see, what we show and how we look are fundamental organizational concerns made ever more salient by the affordances, dynamics, and discourses of the digital age. Contemporary organizing practices are awash with material, mediated and managed visibilities: companies erect glass buildings...

Age dynamic of physical condition changes in pre-school age girls, schoolgirls and students, living in conditions of Eastern Siberia

Directory of Open Access Journals (Sweden)

V.Y. Lebedinskiy

2017-12-01

Full Text Available Purpose: to analyze dynamic of physical condition, considering sex (females and age of the tested, living in region with unfavorable ecology. Material: we studied pre school age girls (n=1580, age 4-7 years. In the research we did not include children with chronic diseases, who were under observation. We tested schoolgirls (n=3211, age 7-17 years and girl students (n=5827, age 17-21 years, 1-4 years of study. Girl students were divided into five age groups: from 17 to 21 years. All participants lived in conditions of Eastern Siberia (Irkutsk. This region is characterized by unfavorable ecology and climate geographic characteristics. Results: in dynamic of physical condition of pre-school girls, schoolgirls and students we marked out three substantial periods of it characteristics' changes. Age 7-8 years is critical (transition from 1st to 2nd stage. The least values of these characteristics are found in older (after 17-18 years ages. In students we observed relative stabilization of these indicators. Conclusions: the received results shall be considered in building physical education training process in pre-school educational establishments, secondary comprehensive schools and higher educational establishments.

Hisar in Leskovac at the end of the early iron age

Directory of Open Access Journals (Sweden)

Stojić Milorad

2007-01-01

Full Text Available All parts of the site Hisar in Leskovac provided material from Iron Age III according to the division by M. Garašanin (mainly from the 5th century BC. Four or perhaps five habitations from this period, in relation to the excavated surface (app. 15 000 m2, indicate a settlement with a larger number of dwelling places. Its architecture - wattle and daub huts and dug outs - has no particular characteristics, and is similar to habitations from previous periods in the Morava valley. Archaeological material from Iron Age III includes pottery made on the wheel of Greek style, hand made pottery and decorative silver and bronze objects.

T-lymphocyte subsets in West African children: impact of age, sex, and season

DEFF Research Database (Denmark)

Lisse, I M; Aaby, P; Whittle, H

1997-01-01

method to determine T-lymphocyte subsets. RESULTS: We found differences by age, sex, and season, whereas there were no significant differences by birth order, twinning, or ethnic group. The CD4+ percentage declined from birth to age 2 years, at which time it started to increase to higher levels at age 4......OBJECTIVE: There has been no reference material for T-lymphocyte subsets for normal children in developing countries. We therefore used T-lymphocyte subset determinations among children in three different studies in Guinea-Bissau to construct age-related reference material and to examine possible...... determinants of T-lymphocyte subset levels. METHODS: A total of 803 healthy West African children younger than 6 years were included in the three community studies of T-lymphocyte subsets among twins and singletons, after measles infection and after measles immunization. We used the immunoalkaline phosphatase...

Ageing under mechanical stress: first experiments for a silver based multilayer mirror

Science.gov (United States)

Lalo, Arnaud; Ravel, Guillaume; Ignat, Michel; Cousin, Bernard; Swain, Michael V.

2017-11-01

Improving materials and devices reliability is a major concern to the spatial industry. Results are reported for satellite mirrors-like specimens consisting in oxide-protected metal systems. Optical coatings were deposited by electron beam evaporation. Mechanical stress fields in multi-layered materials play an important role. The stress state can have far-reaching implications both in kinetics and thermodynamics. Therefore an integrated apparatus with four-point bending equipment was designed. The technique allowed us to exert stress into a film or a system of films on a substrate concurrently with thermal treatment. In order to achieve the first tests performed with the help of the apparatus, various preliminary characterizations were required. The article reports the preliminary micro-mechanical testing of the materials (ultra micro-indentation to evaluate the elastic modulus of the samples materials and wafer curvature technique to determine the specimen residual stress) and the first ageing experiment. Experimental evidence of accelerated ageing under stress is successfully reported.

Accelerated Aging Test for Plastic Scintillator Gamma Ray Detectors

Energy Technology Data Exchange (ETDEWEB)

Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-05-12

Polyvinyl toluene (PVT) and polystyrene (PS), collectively referred to as “plastic scintillator,” are synthetic polymer materials used to detect gamma radiation, and are commonly used in instrumentation. Recent studies have revealed that plastic scintillator undergoes an environmentally related material degradation that adversely affects performance under certain conditions and histories. A significant decrease in gamma ray sensitivity has been seen in some detectors in systems as they age. The degradation of sensitivity of plastic scintillator over time is due to a variety of factors, and the term “aging” is used to encompass all factors. Some plastic scintillator samples show no aging effects (no significant change in sensitivity over more than 10 years), while others show severe aging (significant change in sensitivity in less than 5 years). Aging effects arise from weather (variations in heat and humidity), chemical exposure, mechanical stress, light exposure, and loss of volatile components. The damage produced by these various causes can be cumulative, causing observable damage to increase over time. Damage may be reversible up to some point, but becomes permanent under some conditions. It has been demonstrated that exposure of plastic scintillator in an environmental chamber to 30 days of high temperature and humidity (90% relative humidity and 55°C) followed by a single cycle to cold temperature (-30°C) will produce severe fogging in all PVT samples. This thermal cycle will be referred to as the “Accelerated Aging Test.” This document describes the procedure for performing this Accelerated Aging Test.

High reliability solid refractive index matching materials for field installable connections in FTTH network

Science.gov (United States)

Saito, Kotaro; Kihara, Mitsuru; Shimizu, Tomoya; Yoneda, Keisuke; Kurashima, Toshio

2015-06-01

We performed environmental and accelerated aging tests to ensure the long-term reliability of solid type refractive index matching material at a splice point. Stable optical characteristics were confirmed in environmental tests based on an IEC standard. In an accelerated aging test at 140 °C, which is very much higher than the specification test temperature, the index matching material itself and spliced fibers passing through it had steady optical characteristics. Then we performed an accelerated aging test on an index matching material attached to a built-in fiber before splicing it in the worst condition, which is different from the normal use configuration. As a result, we confirmed that the repeated insertion and removal of fiber for splicing resulted in failure. We consider that the repetition of adhesion between index matching material and fibers causes the splice to degrade. With this result, we used the Arrhenius model to estimate a median lifetime of about 68 years in a high temperature environment of 60 °C. Thus solid type index matching material at a splice point is highly reliable over long periods under normal conditions of use.

Hypermnesia: a further examination of age differences between young and older adults.

Science.gov (United States)

Otani, Hajime; Kato, Koichi; Von Glahn, Nicholas R; Nelson, Meghann E; Widner, Robert L; Goernert, Phillip N

2008-05-01

Previous studies that examined age differences in hypermnesia reported inconsistent results. The present experiment investigated whether the different study materials in these studies were responsible for the inconsistency. In particular, the present experiment examined whether the use of a video, as opposed to words and pictures, would eliminate previously reported age differences in hypermnesia. Fifteen college students and 15 older adults viewed a 3-minute video clip followed by two free-recall tests. The results indicated that older adults, as a whole, did not show hypermnesia. However, when older adults were divided into low and high memory groups based on test 1 performance, the high memory group showed hypermnesia whereas the low memory group did not show hypermnesia. The older adults in the low memory group were significantly older than the older adults in the high memory group - indicating that hypermnesia is inversely related to age in older adults. Reminiscence did not show an age-related difference in either the low or high memory group whereas inter-test forgetting did show an age difference in the low memory group. As expected, older adults showed greater inter-test forgetting than young adults in the low memory group. Findings from the present experiment suggest that video produces a pattern of results that is similar to the patterns obtained when words and pictures are used as study material. Thus, it appears that the nature of study material is not the source of inconsistency across the previous studies.

Seismic-fragility tests of new and accelerated-aged Class 1E battery cells

International Nuclear Information System (INIS)

Bonzon, L.L.; Janis, W.J.; Black, D.A.; Paulsen, G.A.

1987-01-01

The seismic-fragility response of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the potential survivability of a battery given a seismic event. Prior reports in this series discussed the seismic-fragility tests and results for three specific naturally-aged cell types: 12-year old NCX-2250, 10-year old LCU-13, and 10-year old FHC-19. This report focuses on the complementary approach, namely, the seismic-fragility response of accelerated-aged batteries. Of particular interest is the degree to which such approaches accurately reproduce the actual failure modes and thresholds. In these tests the significant aging effects observed, in terms of seismic survivability, were: embrittlement of cell cases, positive bus material and positive plate grids; and excessive sulphation of positive plate active material causing hardening and expansion of positive plates. The IEEE Standard 535 accelerated aging method successfully reproduced seismically significant aging effects in new cells but accelerated grid embrittlement an estimated five years beyond the conditional age of other components

Age distribution of abnormal pap smear in a secondary hospital in ...

African Journals Online (AJOL)

Age distribution of abnormal pap smear in a secondary hospital in south-west Nigeria. ... Objective: To determine the age distribution pattern of abnormal Paps smear in women in our environment in order to have a basis for the points of entry and exit for cervical cancer screening protocol. Materials and Method: In this ...

Ageing of fibre reinforced polymer composite selected as a bearing material for Rams of 540 MWe fuelling machine

International Nuclear Information System (INIS)

Limaye, P.K.; Soni, N.L.; Agrawal, R.G.

2006-01-01

Fibre-reinforced-polymer-composite material has been suggested as a bearing material to overcome tribological problems witnessed during the testing of Ram assembly of the 540 MWe fuelling machine at RTD. After successful trials at B-Ram the composite material has been adapted for B-RAM, C-Ram and RDB head at fuelling machines being tested at RTD, Hall 7 and at Tarapur. Laboratory evaluations were also carried out at Tribology Lab RTD to study effect of radiation on the composite. Paper deals with the various aspects of life prediction of this material in term of wear and radiation damage. (author)

Study of properties of Pvdf aged and non aged in petroleum; Estudo das propriedades de PVDF envelhecido e nao envelhecido em petroleo

Energy Technology Data Exchange (ETDEWEB)

Oliveira, G.L.; Costa, M.F. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais], e-mail: geovaniolo@metalmat.ufrj.br

2010-07-01

The use polymer materials in complex structure such as flexible risers to offshore application is increasingly on the rise. One the materials used in these structures is poly(vinylidene fluoride) (PVDF). Attentive to the challenges found in the environments in which these structures are employed, PVDF copolymer samples were prepared by compression molding. After, materials were aged in petroleum at 80 deg C to assess effect of fluid in polymer. Characterization of samples was carried out by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and tensile stress according to ASTM D 638. Instrumented indentation testing applying Vickers indenter was used to assess the effect of petroleum in PVDF. (author)

Age-related differences in metabolites in the posterior cingulate cortex and hippocampus of normal ageing brain: A 1H-MRS study

International Nuclear Information System (INIS)

Reyngoudt, Harmen; Claeys, Tom; Vlerick, Leslie; Verleden, Stijn; Acou, Marjan; Deblaere, Karel; De Deene, Yves; Audenaert, Kurt; Goethals, Ingeborg; Achten, Eric

2012-01-01

Objective: To study age-related metabolic changes in N-acetylaspartate (NAA), total creatine (tCr), choline (Cho) and myo-inositol (Ins). Materials and methods: Proton magnetic resonance spectroscopy ( 1 H-MRS) was performed in the posterior cingulate cortex (PCC) and the left hippocampus (HC) of 90 healthy subjects (42 women and 48 men aged 18–76 years, mean ± SD, 48.4 ± 16.8 years). Both metabolite ratios and absolute metabolite concentrations were evaluated. Analysis of covariance (ANCOVA) and linear regression were used for statistical analysis. Results: Metabolite ratios Ins/tCr and Ins/H 2 O were found significantly increased with age in the PCC (P 2 O was only observed in the PCC (P 1 H-MRS results in these specific brain regions can be important to differentiate normal ageing from age-related pathologies such as mild cognitive impairment (MCI) and Alzheimer's disease.

Biomechanical testing and material characterization for the rat large intestine: regional dependence of material parameters.

Science.gov (United States)

Sokolis, Dimitrios P; Orfanidis, Ioannis K; Peroulis, Michalis

2011-12-01

The function of the large bowel is to absorb water from the remaining indigestible food matter and subsequently pass useless waste material from the body, but there has been only a small amount of data in the literature on its biomechanical characteristics that would facilitate our understanding of its transport function. Our study aims to fill this gap by affording comprehensive inflation/extension data of intestinal segments from distinct areas, spanning a physiologically relevant deformation range (100-130% axial stretches and 0-15 mmHg lumen pressures). These data were characterized by the Fung-type exponential model in the thick-walled setting, showing reasonable agreement, i.e. root-mean-square error ~30%. Based on optimized material parameters, i.e. a(1)testing and material characterization results for the large intestine of healthy young animals are expected to aid in comprehending the adaptation/remodeling that occurs with ageing, pathological conditions and surgical procedures, as well as for the development of suitable biomaterials for replacement.

A Feature Analysis of Risk Factors for Stroke in the Middle-Aged Adults

OpenAIRE

Haewon Byeon; Hyeung Woo Koh

2015-01-01

In order to maintain health during middle age and achieve successful aging, it is important to elucidate and prevent risk factors of middle-age stroke. This study investigated high risk groups of stroke in middle age population of Korea and provides basic material for establishment of stroke prevention policy by analyzing sudden perception of speech/language problems and clusters of multiple risk factors. This study analyzed 2,751 persons (1,191 males and 1,560 females) aged 40–59 who partici...

Dictionary materials engineering, materials testing

International Nuclear Information System (INIS)

1994-01-01

This dictionary contains about 9,500 entries in each part of the following fields: 1) Materials using and selection; 2) Mechanical engineering materials -Metallic materials - Non-metallic inorganic materials - Plastics - Composites -Materials damage and protection; 3) Electrical and electronics materials -Conductor materials - Semiconductors - magnetic materials - Dielectric materials - non-conducting materials; 4) Materials testing - Mechanical methods - Analytical methods - Structure investigation - Complex methods - Measurement of physical properties - Non-destructive testing. (orig.) [de

Relation of Obesity and Menarche Age among

Directory of Open Access Journals (Sweden)

Shila Berenjy

2008-12-01

Full Text Available Objective: The aim of this study was to investigate the relation between overweight and obesity among adolescent students and age of menarche.Materials and Methods: In a cross-sectional study 399 urban adolescent girls aged 11-14 years old were selected from schools of Kermanshah city in Iran. Anthropometric examinations including, triceps skin fold (TSF, mid arm circumference (MAC, body fat percentage (BF %, were measured and information on age of menarch and student’s demographics were collected. Results: The results showed that age, body mass index (BMI and menarche age were:12.63+1.01 year, 17.71+2.94 kg/m2 and 12.16+1.18 year respectively. Prevalence of overweight in respondents was 23.2%, however; prevalence of obesity was 23.2% for 11 years old , 22.4% for12 years olds , 24% of 13 years old  and 23.5% of 14 years old. Conclusion: There was a reverse relation  between BMI and age of menarche, however; it was not significant (p>0.1. This study suggests a high prevalence of obesity and relation between BMI and anthropometric parameters in adolesent girls.

Effects of Aging on Hippocampal Neurogenesis After Irradiation

International Nuclear Information System (INIS)

Cheng, Zoey; Li, Yu-Qing; Wong, C. Shun

2016-01-01

Purpose: To assess the influence of aging on hippocampal neuronal development after irradiation (IR). Methods and Materials: Male mice, 2, 4, 6, 12, and 18 months of age, were given a single dose of 0 or 5 Gy of IR. A bromodeoxyuridine (BrdU) incorporation study was used to label newborn cells. Neural progenitors, newborn neurons, and microglia in dentate gyrus (DG) were identified by phenotypic markers, and their numbers were quantified by nonbiased stereology 9 weeks after IR. Results: BrdU-positive or newborn cells in DG decreased with aging and after IR. The number of neuroblasts and newborn neurons decreased with aging, and a further significant reduction was observed after IR. Total type 1 cells (the putative neural stem cells), and newborn type 1 cells decreased with aging, and further reduction in total type 1 cells was observed after IR. Aging-associated activation of microglia in hippocampus was enhanced after IR. Conclusions: The aging-associated decline in hippocampal neurogenesis was further inhibited after IR. Ablation of neural progenitors and activation of microglia may contribute to the inhibition of neuronal development after IR across all ages.

Effects of Aging on Hippocampal Neurogenesis After Irradiation

Energy Technology Data Exchange (ETDEWEB)

Cheng, Zoey [Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Institute of Medical Science, University of Toronto, Toronto, Ontario (Canada); Li, Yu-Qing [Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Wong, C. Shun, E-mail: shun.wong@sunnybrook.ca [Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Institute of Medical Science, University of Toronto, Toronto, Ontario (Canada); Departments of Radiation Oncology and Medical Biophysics, University of Toronto, Toronto, Ontario (Canada)

2016-04-01

Purpose: To assess the influence of aging on hippocampal neuronal development after irradiation (IR). Methods and Materials: Male mice, 2, 4, 6, 12, and 18 months of age, were given a single dose of 0 or 5 Gy of IR. A bromodeoxyuridine (BrdU) incorporation study was used to label newborn cells. Neural progenitors, newborn neurons, and microglia in dentate gyrus (DG) were identified by phenotypic markers, and their numbers were quantified by nonbiased stereology 9 weeks after IR. Results: BrdU-positive or newborn cells in DG decreased with aging and after IR. The number of neuroblasts and newborn neurons decreased with aging, and a further significant reduction was observed after IR. Total type 1 cells (the putative neural stem cells), and newborn type 1 cells decreased with aging, and further reduction in total type 1 cells was observed after IR. Aging-associated activation of microglia in hippocampus was enhanced after IR. Conclusions: The aging-associated decline in hippocampal neurogenesis was further inhibited after IR. Ablation of neural progenitors and activation of microglia may contribute to the inhibition of neuronal development after IR across all ages.

Materialism In The Context Of Luxury Consumers

Directory of Open Access Journals (Sweden)

Claudia Rosa Acevedo

2015-11-01

Full Text Available In this article, the established objective is to identify the relationship between socio demographic variables and materialism of the construct in the context of luxury consumer segment. To measure materialism used the theoretical model Richins (2004, tested and adapted nationally by Ponchio and Spider (2007. Through a quantitative survey of 320 consumers in São Paulo, we tested the relationship between the variables revealing results were compared to previous studies on the difference between the sociodemographic contexts. In conclusion, it can be seen that the luxury segment responds differently to the previous study. And unlike materialism identified himself only for the age group of 18 and 29, in relation to the other. The variables gender and financial income showed no distinction between established categories.

Insights into accelerated aging of SSL luminaires

Science.gov (United States)

Davis, J. Lynn; Lamvik, Michael; Bittle, James; Shepherd, Sarah; Yaga, Robert; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy

2013-09-01

Although solid-state lighting (SSL) products are often intended to have product lifetimes of 15 years or more, the rapid change in technology has created a need for accelerated life tests (ALTs) that can be performed in the span of several months. A critical element of interpreting results from any systems-level ALT is understanding of the impact of the test environment on each component. Because of its ubiquity in electronics, the use of temperature-humidity environments as potential ALTs for SSL luminaires was investigated. Results from testing of populations of three commercial 6" downlights in environments of 85°C and 85% relative humidity (RH) and 75°C and 75% RH are reported. These test environments were found to accelerate lumen depreciation of the entire luminaire optical system, including LEDs, lenses, and reflectors. The effects of aging were found to depend strongly on both the optical materials that were used and the design of the luminaire; this shows that the lumen maintenance behavior of SSL luminaires must be addressed at the optical systems level. Temperature-Humidity ALTs can be a useful test in understand lumainaire depreciation provided that proper consideration is given to the different aging rates of various materials. Since the impact of the temperature-humidity environment varies among components of the optical system, uniform aging of all system components in a single test is difficult to achieve.

Parental age at delivery and a man's semen quality

DEFF Research Database (Denmark)

Priskorn, Lærke; Jensen, Tina K; Lindahl-Jacobsen, Rune

2014-01-01

STUDY QUESTION: Is parental age at delivery associated with a man's semen quality? SUMMARY ANSWER: In this large register-based study both mother's and father's age are found to have minimal effects on semen quality in men. WHAT IS KNOWN ALREADY: Both maternal and paternal age have been associated...... with a range of adverse health effects in the offspring. Given the varied health effects of parental age upon offspring, and the sensitivity of genital development to external factors, it is plausible that the age of a man's mother and father at conception may impact his reproductive health. To our knowledge...... this is the first examination of the effects of parental age on semen quality. STUDY DESIGN, SIZE, DURATION: A retrospective cohort study of 10 965 men with semen data and parental data. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study was based on Danish men referred to the Copenhagen Sperm Analysis Laboratory...

Novel ageing-biomarker discovery using data-intensive technologies.

Science.gov (United States)

Griffiths, H R; Augustyniak, E M; Bennett, S J; Debacq-Chainiaux, F; Dunston, C R; Kristensen, P; Melchjorsen, C J; Navarrete, Santos A; Simm, A; Toussaint, O

2015-11-01

Ageing is accompanied by many visible characteristics. Other biological and physiological markers are also well-described e.g. loss of circulating sex hormones and increased inflammatory cytokines. Biomarkers for healthy ageing studies are presently predicated on existing knowledge of ageing traits. The increasing availability of data-intensive methods enables deep-analysis of biological samples for novel biomarkers. We have adopted two discrete approaches in MARK-AGE Work Package 7 for biomarker discovery; (1) microarray analyses and/or proteomics in cell systems e.g. endothelial progenitor cells or T cell ageing including a stress model; and (2) investigation of cellular material and plasma directly from tightly-defined proband subsets of different ages using proteomic, transcriptomic and miR array. The first approach provided longitudinal insight into endothelial progenitor and T cell ageing. This review describes the strategy and use of hypothesis-free, data-intensive approaches to explore cellular proteins, miR, mRNA and plasma proteins as healthy ageing biomarkers, using ageing models and directly within samples from adults of different ages. It considers the challenges associated with integrating multiple models and pilot studies as rational biomarkers for a large cohort study. From this approach, a number of high-throughput methods were developed to evaluate novel, putative biomarkers of ageing in the MARK-AGE cohort. Crown Copyright © 2015. Published by Elsevier Ireland Ltd. All rights reserved.

Effect of accelerated aging on translucency of monolithic zirconia

Directory of Open Access Journals (Sweden)

O. Abdelbary

2016-12-01

Conclusion: Thickness of zirconia has significant effect on translucency. Aging has significant effect on thinner sections of zirconia. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.

Aging and life extension of major light water reactor components

International Nuclear Information System (INIS)

Shah, V.N.; MacDonald, P.E.

1993-01-01

An understanding of the aging degradation of the major pressurized and boiling water reactor structures and components is given. The design and fabrication of each structure or component is briefly described followed by information on the associated stressors. Interactions between the design, materials and various stressors that cause aging degradation are reviewed. In many cases, aging degradation problems have occurred, and the plant experience to date is analyzed. The discussion summarize the available aging-related information and are supported with extensive references, including references to US Nuclear Regulatory Commission (USNRC) documents, Electric Power Research Institute reports, US and international conference proceedings and other publications

Age- and sex-specific thorax finite element model development and simulation.

Science.gov (United States)

Schoell, Samantha L; Weaver, Ashley A; Vavalle, Nicholas A; Stitzel, Joel D

2015-01-01

The shape, size, bone density, and cortical thickness of the thoracic skeleton vary significantly with age and sex, which can affect the injury tolerance, especially in at-risk populations such as the elderly. Computational modeling has emerged as a powerful and versatile tool to assess injury risk. However, current computational models only represent certain ages and sexes in the population. The purpose of this study was to morph an existing finite element (FE) model of the thorax to depict thorax morphology for males and females of ages 30 and 70 years old (YO) and to investigate the effect on injury risk. Age- and sex-specific FE models were developed using thin-plate spline interpolation. In order to execute the thin-plate spline interpolation, homologous landmarks on the reference, target, and FE model are required. An image segmentation and registration algorithm was used to collect homologous rib and sternum landmark data from males and females aged 0-100 years. The Generalized Procrustes Analysis was applied to the homologous landmark data to quantify age- and sex-specific isolated shape changes in the thorax. The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant model was morphed to create age- and sex-specific thoracic shape change models (scaled to a 50th percentile male size). To evaluate the thoracic response, 2 loading cases (frontal hub impact and lateral impact) were simulated to assess the importance of geometric and material property changes with age and sex. Due to the geometric and material property changes with age and sex, there were observed differences in the response of the thorax in both the frontal and lateral impacts. Material property changes alone had little to no effect on the maximum thoracic force or the maximum percent compression. With age, the thorax becomes stiffer due to superior rotation of the ribs, which can result in increased bone strain that can increase the risk of fracture. For the 70-YO models

Long-Term Aging Diagnosis of Rotor Steel Using Acoustic Nonlinearity

Energy Technology Data Exchange (ETDEWEB)

Kim, Chung Seok; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of); Park, Ik Keun; Hyun, Chang Yong [Seoul National University of Science and Tecnology, Seoul (Korea, Republic of)

2011-12-15

The long-term aging of ferritic 2.25CrMo steel was characterized using the acoustic nonlinear effect in order to apply to diagnose the degradation behavior of structural materials. We measured the acoustic nonlinearity parameter for each thermally aged specimen by the higher harmonic-generation technique. The acoustic nonlinearity parameter increased with aging time due to equilibrium M6C carbide precipitation, and has a favorable linear relation with Rockwell hardness. This study suggests that acoustic nonlinearity testing may be applicable to diagnostics on strength degradation in rotor steels.

MRI assessment of myelination: an age standardization

Energy Technology Data Exchange (ETDEWEB)

Staudt, M. (Kinderklinik Dritter Orden, Passau (Germany)); Schropp, C. (Kinderklinik Dritter Orden, Passau (Germany)); Staudt, F. (Kinderklinik Dritter Orden, Passau (Germany)); Obletter, N. (Radiologische Praxis, Klinikum Ingolstadt (Germany)); Bise, K. (Neuropathologisches Inst., Muenchen Univ. (Germany)); Breit, A. (MR Tomographie, Klinikum Passau (Germany)); Weinmann, H.M. (Kinderklinik Schwabing, Muenchen (Germany))

1994-04-01

777 cerebral MRI examinations of children aged 3 days to 14 years were staged for myelination to establish an age standardization. Staging was performed using a system proposed in a previous paper, separately ranking 10 different regions of the brain. Interpretation of the results led to the identification of foue clinical diagnoses that are frequently associated with delays in myelination: West syndrome, cerebral palsy, developmental retardation, and congenital anomalies. In addition, it was found that assessment of myelination in children with head injuries was not practical as alterations in MRI signal can simulate earlier stages of myelination. Age limits were therefore calculated from the case material after excluding all children with these conditions. When simplifications of the definition of the stages are applied, these age limits for the various stages of myelination of each of the 10 regions of the brain make the staging system applicable for routine assessment of myelination. (orig.)

A strategy study on the technology development for key nuclear structural materials

International Nuclear Information System (INIS)

Hong, Jun Hwa; Jeong, Youg Hwan; Kim, Tae Kyu

2012-01-01

In order to realize the advanced long-life PWRs and new Generation-IV nuclear systems, it is pre-requisite to establish or ensure the several key materials technology. In this study, we proposed the several key needs and directions for the key materials issues. Each issue is envisioned and described below. 1) Development of innovative nuclear structural materials with extreme environment-resistance for advanced G-IV systems 2) Improvement/development of key reactor materials for advanced and long -life PWRs. 3) Development of technologies against nuclear materials aging degradation

Materials challenges supporting new sodium fast reactor designs

International Nuclear Information System (INIS)

Gelineau, O.; Goff, S. Dubiez-le; Dubuisson, Ph.; Dalle, F.; Blat, M.

2009-01-01

Sodium Fast Reactor is considered in France as the most mature technology of the different Generation IV systems. In the short-term the designing work is focused on the identification of the potential tracks to improve competitiveness, safety, efficiency and to reduce cost. In that frame the materials have a key role to play. This paper is focused on the new materials envisaged and on the Research and Development program launched in France by Areva NP, CEA and EDF in order to sustain the innovative design options: ferritic steels as candidates for exchangers, steam generators and possibly sodium circuits, optimization of materials and fabrication processes to improve safety and risk management, extension of material databases to take into account the 60 years life duration including irradiation and ageing effect. (author)

Manufacturing of aluminum composite material using stir casting process

International Nuclear Information System (INIS)

Jokhio, M.H.; Panhwar, M.I.; Unar, M.A.

2011-01-01

Manufacturing of aluminum alloy based casting composite materials via stir casting is one of the prominent and economical route for development and processing of metal matrix composites materials. Properties of these materials depend upon many processing parameters and selection of matrix and reinforcements. Literature reveals that most of the researchers are using 2, 6 and 7 xxx aluminum matrix reinforced with SiC particles for high strength properties whereas, insufficient information is available on reinforcement of 'AI/sub 2/O/sub 3/' particles in 7 xxx aluminum matrix. The 7 xxx series aluminum matrix usually contains Cu-Zn-Mg; Therefore, the present research was conducted to investigate the effect of elemental metal such as Cu-Zn-Mg in aluminum matrix on mechanical properties of stir casting of aluminum composite materials reinforced with alpha 'AI/sub 2/O/sub 3/' particles using simple foundry melting alloying and casting route. The age hardening treatments were also applied to study the aging response of the aluminum matrix on strength, ductility and hardness. The experimental results indicate that aluminum matrix cast composite can be manufactured via conventional foundry method giving very good responses to the strength and ductility up to 10% 'AI/sub 2/O/sub 3/' particles reinforced in aluminum matrix. (author)

Manufacturing of Aluminum Composite Material Using Stir Casting Process

Directory of Open Access Journals (Sweden)

Muhammad Hayat Jokhio

2011-01-01

Full Text Available Manufacturing of aluminum alloy based casting composite materials via stir casting is one of the prominent and economical route for development and processing of metal matrix composites materials. Properties of these materials depend upon many processing parameters and selection of matrix and reinforcements. Literature reveals that most of the researchers are using 2, 6 and 7xxx aluminum matrix reinforced with SiC particles for high strength properties whereas, insufficient information is available on reinforcement of \\"Al2O3\\" particles in 7xxx aluminum matrix. The 7xxx series aluminum matrix usually contains Cu-Zn-Mg. Therefore, the present research was conducted to investigate the effect of elemental metal such as Cu-Zn-Mg in aluminum matrix on mechanical properties of stir casting of aluminum composite materials reinforced with alpha \\"Al2O3\\" particles using simple foundry melting alloying and casting route. The age hardening treatments were also applied to study the aging response of the aluminum matrix on strength, ductility and hardness. The experimental results indicate that aluminum matrix cast composite can be manufactured via conventional foundry method giving very good responses to the strength and ductility up to 10% \\"Al2O3\\" particles reinforced in aluminum matrix.

Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites.

Science.gov (United States)

D'Alpino, Paulo Henrique Perlatti; Svizero, Nádia da Rocha; Bim Júnior, Odair; Valduga, Claudete Justina; Graeff, Carlos Frederico de Oliveira; Sauro, Salvatore

2016-06-01

The aim of this study is to evaluate the distribution of the filler size along with the zeta potential, and the integrity of silane-bonded filler surface in different types of restorative dental composites as a function of the material age condition. Filtek P60 (hybrid composite), Filtek Z250 (small-particle filled composite), Filtek Z350XT (nanofilled composite), and Filtek Silorane (silorane composite) (3M ESPE) were tested at different stage condition (i.e., fresh/new, aged, and expired). Composites were submitted to an accelerated aging protocol (Arrhenius model). Specimens were obtained by first diluting each composite specimen in ethanol and then dispersed in potassium chloride solution (0.001 mol%). Composite fillers were characterized for their zeta potential, mean particle size, size distribution, via poly-dispersion dynamic light scattering. The integrity of the silane-bonded surface of the fillers was characterized by FTIR. The material age influenced significantly the outcomes; Zeta potential, filler characteristics, and silane integrity varied both after aging and expiration. Silorane presented the broadest filler distribution and lowest zeta potential. Nanofilled and silorane composites exhibited decreased peak intensities in the FTIR analysis, indicating a deficiency of the silane integrity after aging or expiry time. Regardless to the material condition, the hybrid and the small-particle-filled composites were more stable overtime as no significant alteration in filler size distribution, diameter, and zeta potential occurred. A deficiency in the silane integrity in the nanofilled and silorane composites seems to be affected by the material stage condition. The materials conditions tested in this study influenced the filler size distribution, the zeta potential, and integrity of the silane adsorbed on fillers in the nanofilled and silorane composites. Thus, this may result in a decrease of the clinical performance of aforementioned composites, in

Esophageal morphometric and biomechanical changes during aging in rats

DEFF Research Database (Denmark)

Zhao, Jingbo; Gregersen, Hans

of the present study is to investigate the esophageal geometry and biomechanical changes during aging in rats. Materials and methods Twenty-four male Wistar rats, aged from 6 to 22 months, were used in the study. The body weight and the wet weight per length of esophageal segment were measured at the termination...... was found among 12, 18 and 22 months groups (p>0.05). The longitudinal stress-strain curves shifted from right to the left during aging (pstiffness has no obvious...... change after 12 months in the circumferential direction. Furthermore, we confirm that the esophagus was stiffer in the longitudinal direction than in the circumferential direction. Conclusions A pronounced morphometric and biomechanical remodeling was occurred in the rat esophagus during aging...

The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy

Science.gov (United States)

Kotanchik, Joseph N.; Woods, Walter; Zender, George W.

1943-01-01

An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging this material at various combinations of time and temperature. The higher values of yield stress are obtained in material aged at relatively longer times and lower temperatures.

Summary and conclusions of a program addressing aging of nuclear power plant concrete structures

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Hookham, C.J.; Graves, H.L. III

1999-01-01

Research has been conducted by the Oak Ridge National Laboratory to address aging management of nuclear power plant concrete structures. The purpose was to identify potential structural safety issues and acceptance criteria for use in continued service assessments. The focus of this program was on structural integrity rather than on leaktightness or pressure retention of concrete structures. Primary program accomplishments include formulation of a Structural Materials Information Center that contains data and information on the time variation of material properties under the influence of pertinent environmental stressors and aging factors for 144 materials, an aging assessment methodology to identify critical structures and degradation factors that can potentially impact their performance, guidelines and evaluation criteria for use in condition assessments of reinforced concrete structures, and a reliability-based methodology for current condition assessments and estimations of future performance of reinforced concrete nuclear power plant structures. In addition, in-depth evaluations were conducted of several nondestructive evaluation and repair-related technologies to develop guidance on their applicability. (orig.)

Aging and the picture superiority effect in recall.

Science.gov (United States)

Winograd, E; Smith, A D; Simon, E W

1982-01-01

One recurrent theme in the literature on aging and memory is that the decline of memory for nonverbal information is steeper than for verbal information. This research compares verbal and visual encoding using the picture superiority effect, the finding that pictures are remembered better than words. In the first experiment, an interaction was found between age and type of material; younger subjects recalled more pictures than words while older subjects did not. However, the overall effect was small and two further experiments were conducted. In both of these experiments, the picture superiority effect was found in both age groups with no interaction. In addition, performing a semantic orienting task had no effect on recall. The finding of a picture superiority effect in older subjects indicates that nonverbal codes can be effectively used by subjects in all age groups to facilitate memory performance.

Nondestructive Characterization of Aged Components