WorldWideScience

Sample records for aging degradation study

  1. Boiling-Water Reactor internals aging degradation study

    International Nuclear Information System (INIS)

    Luk, K.H.

    1993-09-01

    This report documents the results of an aging assessment study for boiling water reactor (BWR) internals. Major stressors for BWR internals are related to unsteady hydrodynamic forces generated by the primary coolant flow in the reactor vessel. Welding and cold-working, dissolved oxygen and impurities in the coolant, applied loads and exposures to fast neutron fluxes are other important stressors. Based on results of a component failure information survey, stress corrosion cracking (SCC) and fatigue are identified as the two major aging-related degradation mechanisms for BWR internals. Significant reported failures include SCC in jet-pump holddown beams, in-core neutron flux monitor dry tubes and core spray spargers. Fatigue failures were detected in feedwater spargers. The implementation of a plant Hydrogen Water Chemistry (HWC) program is considered as a promising method for controlling SCC problems in BWR. More operating data are needed to evaluate its effectiveness for internal components. Long-term fast neutron irradiation effects and high-cycle fatigue in a corrosive environment are uncertainty factors in the aging assessment process. BWR internals are examined by visual inspections and the method is access limited. The presence of a large water gap and an absence of ex-core neutron flux monitors may handicap the use of advanced inspection methods, such as neutron noise vibration measurements, for BWR

  2. Study for Relation of Pressure and Aging Degradation during LOCA Test

    International Nuclear Information System (INIS)

    Kim, Jong Seog

    2013-01-01

    As result of this test, it was found that low pressure effect in aging was not significant compared with that of temperature. If temperature profile in LOCA test can satisfy the plant LOCA profile, no further analysis of pressure profile for aging degradation is necessary. For environmental qualification of electric equipment in containment building of nuclear power plant, LOCA test should be applied. During the LOCA test, temperature and pressure of LOCA chamber shall be controlled to meet a requirement of plant specific LOCA profile. It is general to keep LOCA test temperature and pressure above the plant specific LOCA profile. If the test temperature is lower than required profile in some time zone while it is higher in other time zone, calculation of total cumulated test temperature is required to compare with that of plant profile. Arrhenius equation can be applied for calculation of total temperature accumulation. If there is a deviation of pressure between test profile and plant specific profile, can we still use the same rule of temperature? Since the Arrhenius equation can't be applied to pressure, analysis of pressure effect to aging degradation is not easy. Study for relation of pressure and aging degradation during LOCA condition is described herein. To Study an aging degradation effect of pressure during LOCA test, comparison of IR during high LOCA pressure and low LOCA pressure were implemented. We expected low IR in high pressure because it contained a high concentration of oxygen which induces high aging degradation. Contrary to our expectation, IR of low pressure was lower than that of high pressure. It is assumed that high vibration of temperature profile to maintain the low pressure at high temperature induced supply of high enthalpy steam into LOCA chamber

  3. Study on Developing Degradation Model for Nuclear Power Plants With Ageing Elements Affected on Operation Parameter

    International Nuclear Information System (INIS)

    Choi, Yong Won; Lim, Sung Won; Lee, Un Chul; Kim, Man Woong; Kim, Kab; Ryu, Yong Ho

    2009-01-01

    As a part of development the evaluation system of safety margin effects for degradation of CANDU reactors, it is required that the degradation model represents the distribution of each ageing factor's value during operating year. Unfortunately, it is not easy to make an explicit relation between the RELAP-CANDU parameters and ageing mechanism because of insufficient data and lack of applicable models. So, operating parameter related with ageing is used for range determination of ageing factor. Then, relation between operating parameter and ageing elements is analyzed and ageing constant values for degradation model are determined. Also the other ageing factor is derived for more accurate ageing analysis

  4. The study of evaluation methodology of the aging and degradation researches

    International Nuclear Information System (INIS)

    Cho, C. J.; Park, Z. H.; Jeong, I. S.

    2001-01-01

    To judge the usefulness of aging related researches like PLIM (Plant lifetime Management) and aging related degradation, et. al. in PSR(Periodic Safety Review), the evaluation methodology of the R and D have been proposed up to now are reviewed. The infometric methodology is considered to be the optimum method for the evaluation of the nuclear related researches. And finally, to increase the objectiveness and reliability of the infometric methodology in the aging and degradation researches, the indexes of safety, technology and economics are introduced. From this study, the infometric methodology has the advantage of the actual engineering evaluation in the nuclear related researches with other methodologies, but for the further research, the effective construction of DB and survey of various statistics in the technical reports and papers are needed

  5. A Comprehensive Study on the Degradation of Lithium-Ion Batteries during Calendar Ageing

    DEFF Research Database (Denmark)

    Stroe, Daniel Loan; Swierczynski, Maciej Jozef; Kær, Søren Knudsen

    2016-01-01

    Lithium-ion batteries are regarded as the key energy storage technology for both e-mobility and stationary renewable energy storage applications. Nevertheless, the Lithium-ion batteries are complex energy storage devices, which are characterized by a complex degradation behavior, which affects both...... their capacity and internal resistance. This paper investigates, based on extended laboratory calendar ageing tests, the degradation of the internal resistance of a Lithium-ion battery. The dependence of the internal resistance increase on the temperature and state-of-charge level have been extensive studied...... and quantified. Based on the obtained laboratory results, an accurate semi-empirical lifetime model, which is able to predict with high accuracy the internal resistance increase of the Lithium-ion battery over a wide temperature range and for all state-of-charge levels was proposed and validated....

  6. 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.

  7. Environmental aging in polycrystalline-Si photovoltaic modules: comparison of chamber-based accelerated degradation studies with field-test data

    Science.gov (United States)

    Lai, T.; Biggie, R.; Brooks, A.; Potter, B. G.; Simmons-Potter, K.

    2015-09-01

    Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following

  8. Perceptual restoration of degraded speech is preserved with advancing age

    NARCIS (Netherlands)

    Saija, Jefta D; Akyürek, Elkan G; Andringa, Tjeerd C; Başkent, Deniz

    Cognitive skills, such as processing speed, memory functioning, and the ability to divide attention, are known to diminish with aging. The present study shows that, despite these changes, older adults can successfully compensate for degradations in speech perception. Critically, the older

  9. Management of age-related degradation for nuclear power plants

    International Nuclear Information System (INIS)

    Gregor, Frank E.

    2004-01-01

    Life extension for nuclear power plants has been studied in the USA for the last six years, largely supported by EPRI, DOE and the USNRC. Though there are diverse opinions for the strategies and priorities of life extension and aging management, one common conclusion has been formulated regarding the need of current maintenance programs having to focus on aging and degradation management. Such program, called 'Maintenance Effectiveness Evaluation and Enhancement' or M3E for short, has been developed to assist plant operators to upgrade and enhance existing programs by integrating aging/degradation management activities for important or critical equipment and components. The key elements of the M3E program consist of the definition and selection of the critical components or commodities to be included in the scope, the survey/inventory of the current programs and their respective action steps, frequencies, corrective measures and extent of coverage, the component/commodity degradation mechanism, sites and severity, safety functions and service environments and lastly, the correlation of degradation/aging with the individual maintenance activities. The degree of correlation provides a measure of effectiveness and the opportunity to identify/specify needed enhancements, abandonment or generation of new maintenance activities. Implementation of the activities can then be prioritized at the option of the plant staff. (author)

  10. Proceeding of 27th domestic symposium on trends in aging management and current status of aging degradation studies in nuclear power plants

    International Nuclear Information System (INIS)

    2000-11-01

    As the 27th domestic symposium of Atomic Energy Research Committee, the Japan Welding Engineering Society, the symposium was held titled as 'Trends of aging managements and current status of aging effect studies in nuclear power plants'. Six speakers gave lectures titled as 'Present status of research on mechanism and prediction method of neutron irradiation embrittlement of pressure vessel steels', 'Present status of research on mechanism and prediction method of environmentally assisted cracking in the LWR environments', 'Domestic and overseas trends of aging management of the LWR plants', 'Trends of prediction/evaluation, inspection/monitoring and repair/replacement technologies for aging of the LWR plants', 'Present status of research on mechanism and prediction method of high cycle thermal fatigue due to the thermal fluid-structure interaction in the LWR environments' and Present status of research on very high cycle fatigue of structural materials'. (T. Tanaka)

  11. Age-related degradation of Westinghouse 480-volt circuit breakers

    International Nuclear Information System (INIS)

    Subudhi, M.; Shier, W.; MacDougall, E.

    1990-07-01

    An aging assessment of Westinghouse DS-series low-voltage air circuit breakers was performed as part of the Nuclear Plant Aging Research (NPAR) program. The objectives of this study are to characterize age-related degradation within the breaker assembly and to identify maintenance practices to mitigate their effect. Since this study has been promulgated by the failures of the reactor trip breakers at the McGuire Nuclear Station in July 1987, results relating to the welds in the breaker pole lever welds are also discussed. The design and operation of DS-206 and DS-416 breakers were reviewed. Failure data from various national data bases were analyzed to identify the predominant failure modes, causes, and mechanisms. Additional operating experiences from one nuclear station and two industrial breaker-service companies were obtained to develop aging trends of various subcomponents. The responses of the utilities to the NRC Bulletin 88-01, which discusses the center pole lever welds, were analyzed to assess the final resolution of failures of welds in the reactor trips. Maintenance recommendations, made by the manufacturer to mitigate age-related degradation were reviewed, and recommendations for improving the monitoring of age-related degradation are discussed. As described in Volume 2 of this NUREG, the results from a test program to assess degradation in breaker parts through mechanical cycling are also included. The testing has characterized the cracking of center-pole lever welds, identified monitoring techniques to determine aging in breakers, and provided information to augment existing maintenance programs. Recommendations to improve breaker reliability using effective maintenance, testing, and inspection programs are suggested. 13 refs., 21 figs., 8 tabs

  12. Nuclear plant service water system aging degradation assessment

    International Nuclear Information System (INIS)

    Jarrell, D.B.; Larson, L.L.; Stratton, R.C.; Bohn, S.J.; Gore, M.L.

    1992-10-01

    This report discusses the second phase of the aging assessment of nuclear plant service water systems (SWSs) which was performed by the Pacific Northwest Laboratory (PNL) to support the US Nuclear Regulatory Commission's (NRC's) Nuclear Plant Aging Research (NPAR) program. The SWS was selected for study because of its essential role in the mitigation of and recovery from accident scenarios involving the potential for core-melt, and because it is subject to a variety of aging mechanisms. The objectives of the SWS task under the NPAR program are to identify and characterize the principal age-related degradation mechanisms relevant to this system, to assess the impact of aging degradation on operational readiness, and to provide a methodology for the management of aging on the service water aspect of nuclear plant safety. The primary degradation mechanism in the SWSs as stated in the Phase I assessment and confirmed by the analysis in Phase II, is corrosion compounded by biologic and inorganic accumulation. It then follows that the most effective means for mitigating degradation in these systems is to pursue appropriate programs to effectively control the water chemistry properties when possible and to use biocidal agents where necessary. A methodology for producing a complete root-cause analysis was developed as a result of needs identified in the Phase I assessment for a more formal procedure that would lend itself to a generic, standardized approach. It is recommended that this, or a similar methodology, be required as a part of the documentation for corrective maintenance performed on the safety-related portions of SWSs to provide an accurate focus for effective management of aging

  13. Evaluation of cable aging degradation based on plant operating condition

    International Nuclear Information System (INIS)

    Kim, Jong-Seog

    2005-01-01

    Extending the lifetime of nuclear power plant [(hereafter referred simply as ''NPP'')] is one of the most important concerns in the world nuclear industry. Cables are one of the long live items which have not been considered to be replaced during the design life of NPP. To extend the cable life beyond the design life, we need to prove that the design life is too conservative compared with the actual aging. Condition monitoring is one of the useful ways for evaluating the aging condition of cable. In order to simulate the natural aging in nuclear power plant, a study on accelerated aging needs to be conducted first. In this paper, evaluations of mechanical aging degradation for cable jacket were performed after accelerated aging under the continuous heating and intermittent heating. Contrary to general expectation, the intermittent heating to cable jacket showed low aging degradation, 50% break-elongation and 60% indenter modulus, compared with continuous heating. With the plant maintenance period of 1 month after every 12 or 18 months operation, we can easily deduce that the life time of cable jacket can be extended much longer than estimated through the general EQ (Environmental Qualification) test, which adopts continuous accelerated aging for determining cable life. Therefore, a systematic approach which considers the actual environment condition of nuclear power plant is required for determining the life of cables. (author)

  14. Perceptual restoration of degraded speech is preserved with advancing age.

    Science.gov (United States)

    Saija, Jefta D; Akyürek, Elkan G; Andringa, Tjeerd C; Başkent, Deniz

    2014-02-01

    Cognitive skills, such as processing speed, memory functioning, and the ability to divide attention, are known to diminish with aging. The present study shows that, despite these changes, older adults can successfully compensate for degradations in speech perception. Critically, the older participants of this study were not pre-selected for high performance on cognitive tasks, but only screened for normal hearing. We measured the compensation for speech degradation using phonemic restoration, where intelligibility of degraded speech is enhanced using top-down repair mechanisms. Linguistic knowledge, Gestalt principles of perception, and expectations based on situational and linguistic context are used to effectively fill in the inaudible masked speech portions. A positive compensation effect was previously observed only with young normal hearing people, but not with older hearing-impaired populations, leaving the question whether the lack of compensation was due to aging or due to age-related hearing problems. Older participants in the present study showed poorer intelligibility of degraded speech than the younger group, as expected from previous reports of aging effects. However, in conditions that induce top-down restoration, a robust compensation was observed. Speech perception by the older group was enhanced, and the enhancement effect was similar to that observed with the younger group. This effect was even stronger with slowed-down speech, which gives more time for cognitive processing. Based on previous research, the likely explanations for these observations are that older adults can overcome age-related cognitive deterioration by relying on linguistic skills and vocabulary that they have accumulated over their lifetime. Alternatively, or simultaneously, they may use different cerebral activation patterns or exert more mental effort. This positive finding on top-down restoration skills by the older individuals suggests that new cognitive training methods

  15. Degradation modeling with application to aging and maintenance effectiveness evaluations

    International Nuclear Information System (INIS)

    Samanta, P.K.; Hsu, F.; Subduhi, M.; Vesely, W.E.

    1990-01-01

    This paper describes a modeling approach to analyze component degradation and failure data to understand the aging process of components. As used here, degradation modeling is the analysis of information on component degradation in order to develop models of the process and its implications. This particular modeling focuses on the analysis of the times of component degradations, to model how the rate of degradation changes with the age of the component. The methodology presented also discusses the effectiveness of maintenance as applicable to aging evaluations. The specific applications which are performed show quantitative models of component degradation rates and component failure rates from plant-specific data. The statistical techniques which are developed and applied allow aging trends to be effectively identified in the degradation data, and in the failure data. Initial estimates of the effectiveness of maintenance in limiting degradations from becoming failures also are developed. These results are important first steps in degradation modeling, and show that degradation can be modeled to identify aging trends. 2 refs., 8 figs

  16. Degradation modeling with application to aging and maintenance effectiveness evaluations

    International Nuclear Information System (INIS)

    Samanta, P.K.; Vesely, W.E.; Hsu, F.; Subudhi, M.

    1991-01-01

    This paper describes a modeling approach to analyze light water reactor component degradation and failure data to understand the aging process of components. As used here, degradation modeling is the analysis of information on component degradation in order to develop models of the process and its implications. This particular modeling focuses on the analysis of the times of component degradations, to model how the rate of degradation changes with the age of the component. The methodology presented also discusses the effectiveness of maintenance as applicable to aging evaluations. The specific applications which are performed show quantitative models of component degradation rates and component failure rates from plant-specific data. The statistical techniques which are developed and applied allow aging trends to be effectively identified in the degradation data, and in the failure data. Initial estimates of the effectiveness of maintenance in limiting degradations from becoming failures also are developed. These results are important first steps in degradation modeling, and show that degradation can be modeled to identify aging trends

  17. Aging degradation of cast stainless steel

    International Nuclear Information System (INIS)

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

    1985-10-01

    A program is being conducted to investigate the significance of in-service embrittlement of cast-duplex stainless steels under light-water reactor operating conditions. Data from room-temperature Charpy-impact tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450 0 C are presented and compared with results from other studies. Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or in reactor service have been characterized. The results indicate that at least two processes contribute to the low-temperature embrittleent of duplex stainless steels, viz., weakening of the ferrite/austenite phase boundary by carbide precipitation and embrittlement of ferrite matrix by the formation of additional phases such as G-phase, Type X, or the α' phase. Carbide precipitation has a significant effect on the onset of embrittlement of CF-8 and -8M grades of stainless steels aged at 400 or 450 0 C. The existing correlations do not accurately represent the embrittlement behavior over the temperature range 300 to 450 0 C. 18 refs., 13 figs

  18. Analyses of component degradation to evaluate maintenance effectiveness and aging effects

    International Nuclear Information System (INIS)

    Samanta, P.K.; Hsu, F.; Subudhi, M.; Vesely, W.E.

    1991-01-01

    This paper describes degradation modeling, an approach for analyzing degradation and failure of components to understand the aging process of components. As used in our study, degradation modeling is the analysis of information on degradation of components for developing models of the degradation process and its implications. This modeling focuses on the analysis of the times of degradations of components, to model how the rate of degradation changes with the age of the component. With this methodology we also determine the effectiveness of maintenance as applicable to aging evaluations. The specific applications which are performed show quantitative models of degradation rates of components and failure rates of components from plant-specific data. The statistical techniques allow aging trends to be identified in the degradation data and in the failure data. Initial estimates of the effectiveness of maintenance in limiting degradations from becoming failures are developed. These results are important first steps in degradation modeling, and show that degradation can be modeled to identify aging trends. 2 refs., 8 figs., 1 tab

  19. Effects of age on long term memory for degraded speech

    Directory of Open Access Journals (Sweden)

    Christiane Thiel

    2016-09-01

    Full Text Available Prior research suggests that acoustical degradation impacts encoding of items into memory, especially in elderly subjects. We here aimed to investigate whether acoustically degraded items, that are initially encoded into memory, are more prone to forgetting as a function of age. Young and old participants were tested with a vocoded and unvocoded serial list learning task involving immediate and delayed free recall. We found that degraded auditory input increased forgetting of previously encoded items, especially in older participants. We further found that working memory capacity predicted forgetting of degraded information in young participants. In old participants, verbal IQ was the most important predictor for forgetting acoustically degraded information. Our data provide evidence that acoustically degraded information, even if encoded, is especially vulnerable to forgetting in old age.

  20. Multiscale Concrete Modeling of Aging Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Hammi, Yousseff [Mississippi State Univ., Mississippi State, MS (United States); Gullett, Philipp [Mississippi State Univ., Mississippi State, MS (United States); Horstemeyer, Mark F. [Mississippi State Univ., Mississippi State, MS (United States)

    2015-07-31

    In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Giner et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].

  1. Degradable polyphosphazene/poly(alpha-hydroxyester) blends: degradation studies.

    Science.gov (United States)

    Ambrosio, Archel M A; Allcock, Harry R; Katti, Dhirendra S; Laurencin, Cato T

    2002-04-01

    Biomaterials based on the polymers of lactic acid and glycolic acid and their copolymers are used or studied extensively as implantable devices for drug delivery, tissue engineering and other biomedical applications. Although these polymers have shown good biocompatibility, concerns have been raised regarding their acidic degradation products, which have important implications for long-term implantable systems. Therefore, we have designed a novel biodegradable polyphosphazene/poly(alpha-hydroxyester) blend whose degradation products are less acidic than those of the poly(alpha-hydroxyester) alone. In this study, the degradation characteristics of a blend of poly(lactide-co-glycolide) (50:50 PLAGA) and poly[(50% ethyl glycinato)(50% p-methylphenoxy) phosphazene] (PPHOS-EG50) were qualitatively and quantitatively determined with comparisons made to the parent polymers. Circular matrices (14mm diameter) of the PLAGA, PPHOS-EG50 and PLAGA-PPHOS-EG50 blend were degraded in non-buffered solutions (pH 7.4). The degraded polymers were characterized for percentage mass loss and molecular weight and the degradation medium was characterized for acid released in non-buffered solutions. The amounts of neutralizing base necessary to bring about neutral pH were measured for each polymer or polymer blend during degradation. The poly(phosphazene)/poly(lactide-co-glycolide) blend required significantly less neutralizing base in order to bring about neutral solution pH during the degradation period studied. The results indicated that the blend degraded at a rate intermediate to that of the parent polymers and that the degradation products of the polyphosphazene neutralized the acidic degradation products of PLAGA. Thus, results from these in vitro degradation studies suggest that the PLAGA-PPHOS-EG50 blend may provide a viable improvement to biomaterials based on acid-releasing organic polymers.

  2. Nuclear plant service water system aging degradation assessment: Phase 1

    International Nuclear Information System (INIS)

    Jarrell, D.B.; Johnson, A.B. Jr.; Zimmerman, P.W.; Gore, M.L.

    1989-06-01

    The initial phase of an aging assessment of nuclear power plant service water systems (SWSs) was performed by the Pacific Northwest Laboratory to support the Nuclear Regulatory Commission Nuclear Plant Aging Research (NPAR) program. The SWS was selected for study because of its essential role in the mitigation of and recovery from accident scenarios involving the potential for core-melt. The objectives of the SWS task under the NPAR program are to identify and characterize the principal aging degradation mechanisms relevant to this system and assess their impact on operational readiness, and to provide a methodology for the mitigation of aging on the service water aspect of nuclear plant safety. The first two of these objectives have been met and are covered in this Phase 1 report. A review of available literature and data-base information indicated that motor operated valve torque switches (an electro-mechanical device) were the prime suspect in component service water systems failures. More extensive and detailed data obtained from cooperating utility maintenance records and personnel accounts contradicted this conclusion indicating that biologic and inorganic accumulation and corrosive attack of service water on component surfaces were, in fact, the primary degradation mechanisms. A review of the development of time dependent risk assessment (aging) models shows that, as yet, this methodology has not been developed to a degree where implementation is reliable. Improvements in the accuracy of failure data documentation and time dependent risk analysis methodology should yield significant gains in relating aging phenomena to probabilistic risk assessment. 23 refs., 8 figs., 10 tabs

  3. Aging degradation of cast stainless steel

    International Nuclear Information System (INIS)

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

    1986-10-01

    A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. Microstructures of cast materials subjected to long-term aging either in reactor service or in the laboratory have been characterized by TEM, SANS, and APFIM techniques. Two precipitate phases, i.e., the Cr-rich α' and Ni- and Si-rich G phase, have been identified in the ferrite matrix of the aged steels. The results indicate that the low-temperature embrittlement is primarily caused by α' precipitates which form by spinodal decomposition. The relative contribution of G phase to loss of toughness is now known. Microstructural data also indicate that weakening of ferrite/austenite phase boundary by carbide precipitates has a significant effect on the onset and extent of embrittlement of the high-carbon CF-8 and CF-8M grades of stainless steels, particularly after aging at 400 or 450 0 C. Data from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450 0 C are presented and correlated with the microstructural results. Thermal aging of the steels results in an increase in tensile strength and a decrease in impact energy, J/sub IC/, and tearing modulus. The fracture toughness results show good agreement with the Charpy-impact data. The effects of compositional and metallurgical variables on loss of toughness are discussed

  4. The positivity bias in aging: Motivation or degradation?

    Science.gov (United States)

    Kalenzaga, Sandrine; Lamidey, Virginie; Ergis, Anne-Marie; Clarys, David; Piolino, Pascale

    2016-08-01

    The question of an emotional memory enhancement in aging, and of a positivity bias in particular, has been the subject of numerous empirical studies in the last decade. However, the roots of such positive preference are not yet well established. Partisans of a motivation-based perspective contend with those arguing that positivity is related to a cognitive or neural degradation. The aim of this study was to introduce some elements concerning positivity effect in aging. We compared immediate (i.e., immediate recall) versus delayed (i.e., delayed recall and recognition) emotional memory performance in 38 young adults, 39 old adults, 37 very old adults, and 41 Alzheimer's disease patients. Moreover, we manipulated the encoding instruction: Either participants received no particular processing instruction, or they had to process the material in a semantic way. The results indicated that the positivity bias is most likely to occur in individuals whose cognitive functions are preserved, after long retention delay, and in experimental conditions that do not constrain encoding. We concluded by highlighting that although these findings seem to be better in line with the motivation, rather than the degradation, perspective, they do not fully support either theory. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  5. 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

  6. Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 1. Artificially aged model samples.

    Science.gov (United States)

    Monico, Letizia; Van der Snickt, Geert; Janssens, Koen; De Nolf, Wout; Miliani, Costanza; Verbeeck, Johan; Tian, He; Tan, Haiyan; Dik, Joris; Radepont, Marie; Cotte, Marine

    2011-02-15

    On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1-3 μm) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (μ-XANES), X-ray fluorescence spectrometry (μ-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR μ-XRD), μ-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and μ-XANES spectra are consistent with the presence of Cr(2)O(3)·2H(2)O (viridian). Moreover, as demonstrated by μ-XANES, the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide], is likely.

  7. Reviewing fluid systems for age-related degradation

    International Nuclear Information System (INIS)

    Smith, Stan

    1991-01-01

    Yankee Atomic Electric Company has developed the component degradation assessment tool (CoDAT), an expert system, that aids in handling and evaluating the large amounts of data required to support the license renewal process for nuclear power station fluid systems. In 1990, CoDAT evaluated the Yankee Nuclear Power Station fluid systems for age-related degradation. Its results are now being used to help focus the plant's maintenance programs and manage the expected degradation. CoDAT uses 'If-Then' rules, developed from industry codes, standards and publications, to determine the potential for 19 age-related degradation mechanisms. Other nuclear utilities pursuing the license renewal option also could use CoDAT. (author)

  8. Age-related degradation of boiling water reactor vessel internals

    International Nuclear Information System (INIS)

    Ware, A.G.; Shah, V.N.

    1992-01-01

    Researchers at the Idaho National Engineering Laboratory performed an assessment of the aging of the reactor internals in boiling water reactors (BWRs), and identified the unresolved technical issues related to the degradation of these components. The overall life-limiting mechanism is intergranular stress corrosion cracking (IGSCC). Irradiation-assisted stress corrosion cracking, fatigue, and thermal aging embrittlement are other potential degradation mechanisms. Several failures in BWR internals have been caused by a combination of factors such as environment, high residual or preload stresses, and flow-induced vibration. The ASME Code Section XI in-service inspection requirements are insufficient for detecting aging-related degradation at many locations in reactor internals. Many of the potential locations for IGSCC or fatigue are not accessible for inspection. (orig.)

  9. Multitasking During Degraded Speech Recognition in School-Age Children.

    Science.gov (United States)

    Grieco-Calub, Tina M; Ward, Kristina M; Brehm, Laurel

    2017-01-01

    Multitasking requires individuals to allocate their cognitive resources across different tasks. The purpose of the current study was to assess school-age children's multitasking abilities during degraded speech recognition. Children (8 to 12 years old) completed a dual-task paradigm including a sentence recognition (primary) task containing speech that was either unprocessed or noise-band vocoded with 8, 6, or 4 spectral channels and a visual monitoring (secondary) task. Children's accuracy and reaction time on the visual monitoring task was quantified during the dual-task paradigm in each condition of the primary task and compared with single-task performance. Children experienced dual-task costs in the 6- and 4-channel conditions of the primary speech recognition task with decreased accuracy on the visual monitoring task relative to baseline performance. In all conditions, children's dual-task performance on the visual monitoring task was strongly predicted by their single-task (baseline) performance on the task. Results suggest that children's proficiency with the secondary task contributes to the magnitude of dual-task costs while multitasking during degraded speech recognition.

  10. OECD/NEA component operational experience, degradation and ageing project

    International Nuclear Information System (INIS)

    Gott, K.; Nevander, O.; Riznic, J.; Lydell, B.

    2015-01-01

    Several OECD Member Countries have agreed to establish the OECD/NEA 'Component Operational Experience, Degradation and Ageing Programme' (CODAP) to encourage multilateral co-operation in the collection and analysis of data relating to degradation and failure of metallic piping and non-piping metallic passive components in commercial nuclear power plants. The scope of the data collection includes service-induced wall thinning, part through-wall cracks, through-wall cracks with and without active leakage, and instances of significant degradation of metallic passive components, including piping pressure boundary integrity. CODAP is the continuation of the 2002-2011 'OECD/NEA Pipe Failure Data Exchange Project' (OPDE) and the Stress Corrosion Cracking Working Group of the 2006-2010 - OECD/NEA SCC and Cable Ageing project - (SCAP). OPDE was formally launched in May 2002. Upon completion of the 3. Term (May 2011), the OPDE project was officially closed to be succeeded by CODAP. In May 2011, 13 countries signed the CODAP first Term agreement. The first Term (2011-2014) work plan includes the development of a web-based relational event database on passive, metallic components in commercial nuclear power plants, a web-based knowledge base on material degradation, codes and standards relating to structural integrity and national practices for managing material degradation. The work plan also addresses the preparation of Topical Reports to foster technical cooperation and to deepen the understanding of national differences in ageing management. These Topical Reports are in the public domain and available for download on the NEA web site. Published in 2014, a first Topical Report addressed flow accelerated corrosion (FAC) of carbon steel and low alloy steel piping. A second Topical Report addresses operating experience with electro-hydraulic control (EHC) and instrument air (IA) system piping

  11. Public opinion on age-related degradation in nuclear power plants

    International Nuclear Information System (INIS)

    Matsuda, Toshihiro

    2005-01-01

    The first objective of this study is to shed light on the public opinion on age-related degradation at nuclear power plants, namely, on how the general public recognizes or views age-related degradation, which is a safety-related issue and one of the factors contributing to accidents and failures which occur at nuclear power plants. The second objective is to look into the impacts of the accident at Mihama Unit 3, which was caused by a failure to check on the piping wall thickness, on the public opinion on age-related degradation. The first survey was conducted in August 2003, followed by the second survey in October 2004, two months after the accident. The surveys found that the age-related degradation is being perceived by people as one of the risk factors that affect the safety of nuclear power plants. The characteristics of the citizens' perceptions toward age-related degradation in the form of piping cracks are that: (a) many respondents feel uneasy but a relatively few people consider that nuclear operators are technologically capable of coping with this problem; (b) many people believe that radioactivity may be released; and (c) numerous respondents consider that signs of cracks must be thoroughly detected through inspections, while on the other hand, a large percentage of the respondents attribute the accident to improper inspections/maintenance. Based on these results, the government and nuclear operators are expected to give most illuminating explanation on the current situation of and remedial measures against age-related degradation at nuclear power plants. As for the effects of the Mihama-3 accident on the public opinion on age-related degradation, it was revealed that the accident has not so significantly affected the general view for the safety of nuclear power plants, but has newly or strongly aroused people's consciousness of two of the risk factors - improper inspections/maintenance and the age-related degradation of piping. (author)

  12. Reliability residual-life prediction method for thermal aging based on performance degradation

    International Nuclear Information System (INIS)

    Ren Shuhong; Xue Fei; Yu Weiwei; Ti Wenxin; Liu Xiaotian

    2013-01-01

    The paper makes the study of the nuclear power plant main pipeline. The residual-life of the main pipeline that failed due to thermal aging has been studied by the use of performance degradation theory and Bayesian updating methods. Firstly, the thermal aging impact property degradation process of the main pipeline austenitic stainless steel has been analyzed by the accelerated thermal aging test data. Then, the thermal aging residual-life prediction model based on the impact property degradation data is built by Bayesian updating methods. Finally, these models are applied in practical situations. It is shown that the proposed methods are feasible and the prediction accuracy meets the needs of the project. Also, it provides a foundation for the scientific management of aging management of the main pipeline. (authors)

  13. Effect of Biochar Amendment and Ageing on Adsorption and Degradation of Two Herbicides.

    Science.gov (United States)

    Zhelezova, Alena; Cederlund, Harald; Stenström, John

    2017-01-01

    Biochar amendment can alter soil properties, for instance, the ability to adsorb and degrade different chemicals. However, ageing of the biochar, due to processes occurring in the soil over time, can influence such biochar-mediated effects. This study examined how biochar affected adsorption and degradation of two herbicides, glyphosate (N-(phosphonomethyl)-glycine) and diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) in soil and how these effects were modulated by ageing of the biochar. One sandy and one clayey soil that had been freshly amended with a wood-based biochar (0, 1, 10, 20 and 30% w / w ) were studied. An ageing experiment, in which the soil-biochar mixtures were aged for 3.5 months in the laboratory, was also performed. Adsorption and degradation were studied in these soil and soil-biochar mixtures, and compared to results from a soil historically enriched with charcoal. Biochar amendment increased the pH in both soils and increased the water-holding capacity of the sandy soil. Adsorption of diuron was enhanced by biochar amendment in both soils, while glyphosate adsorption was decreased in the sandy soil. Ageing of soil-biochar mixtures decreased adsorption of both herbicides in comparison with freshly biochar-amended soil. Herbicide degradation rates were not consistently affected by biochar amendment or ageing in any of the soils. However, glyphosate half-lives correlated with the Freundlich Kf values in the clayey soil, indicating that degradation was limited by availability there.

  14. Delaying aging and the aging-associated decline in protein homeostasis by inhibition of tryptophan degradation

    NARCIS (Netherlands)

    van der Goot, Annemieke T.; Zhu, Wentao; Vazquez-Manrique, Rafael P.; Seinstra, Renee I.; Dettmer, Katja; Michels, Helen; Farina, Francesca; Krijnen, Jasper; Melki, Ronald; Buijsman, Rogier C.; Silva, Mariana Ruiz; Thijssen, Karen L.; Kema, Ido P.; Neri, Christian; Oefner, Peter J.; Nollen, Ellen A. A.

    2012-01-01

    Toxicity of aggregation-prone proteins is thought to play an important role in aging and age-related neurological diseases like Parkinson and Alzheimer's diseases. Here, we identify tryptophan 2,3-dioxygenase (tdo-2), the first enzyme in the kynurenine pathway of tryptophan degradation, as a

  15. Structural degradation of acrylic bone cements due to in vivo and simulated aging.

    Science.gov (United States)

    Hughes, Kerry F; Ries, Michael D; Pruitt, Lisa A

    2003-05-01

    Acrylic bone cement is the primary load-bearing material used for the attachment of orthopedic devices to adjoining bone. Degradation of acrylic-based cements in vivo results in a loss of structural integrity of the bone-cement-prosthesis interface and limits the longevity of cemented orthopedic implants. The purpose of this study is to investigate the effect of in vivo aging on the structure of the acrylic bone cement and to develop an in vitro artificial aging protocol that mimics the observed degradation. Three sets of retrievals are examined in this study: Palacos brand cement retrieved from hip replacements, and Simplex brand cement retrieved from both hip and knee replacement surgeries. In vitro aging is performed using oxidative and acidic environments on three acrylic-based cements: Palacos, Simplex, and CORE. Gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR) are used to examine the evolution of molecular weight and chemical species within the acrylic cements due to both in vivo and simulated aging. GPC analysis indicates that molecular weight is degraded in the hip retrievals but not in the knee retrievals. Artificial aging in an oxidative environment best reproduces this degradation mechanism. FTIR analysis indicates that there exists a chemical evolution within the cement due to in vivo and in vitro aging. These findings are consistent with scission-based degradation schemes in the cement. Based on the results of this study, a pathway for structural degradation of acrylic bone cement is proposed. The findings from this investigation have broad applicability to acrylic-based cements and may provide guidance for the development of new bone cements that resist degradation in the body. Copyright 2003 Wiley Periodicals, Inc.

  16. Ageing degradation in the Gentilly-1 concrete containment building

    International Nuclear Information System (INIS)

    Jaffer, S.; Pentecost, S.; Angell, P.; Shenton, B.

    2015-01-01

    Concrete containment buildings (CCBs) are designed for a service life up to 40 years, but nuclear power plant (NPP) refurbishment can extend service life beyond 60 years. Only limited testing can be conducted on an in-service CCB. The Gentilly-1 (G-1) NPP is in a safe, sustainable shutdown state and the G-1 CCB was available for testing to determine age-related degradation that may be relevant to operating CCBs. Visual observation of the G-1 CCB helped to identify various signs of degradation. However, field testing, via concrete removal, was performed to: (i) examine reinforcing bars and concrete to determine their condition and in-situ stresses and (ii) examine condition of post-tensioned (P-T) wires. The concrete was also subjected to laboratory tests to evaluate its physical, mechanical and chemical properties such as compressive strength, carbonation depth, chloride content and presence of internal degradation. The degradation mechanisms that were clearly visible include macro- and micro-cracking, efflorescence, and weathering. The reinforcing bars in the perimeter wall and dome exposed during the program showed no evidence of active corrosion. Corrosion products were observed on the surfaces of most exposed P-T wires in the perimeter wall, but none were present on P-T wires exposed in the dome. Laboratory testing on the concrete cores extracted from the CCB revealed compressive strength in excess of the design requirements, low carbonation depths (< 10 mm) and no appreciable chlorides. Micro-cracking was observed in the samples recovered from the wall and dome. To date, the observed micro-cracking has had no apparent visible affect on the performance of the CCB concrete. (authors)

  17. Aging and low-flow degradation of auxilary feedwater pumps

    International Nuclear Information System (INIS)

    Adams, M.L.

    1992-01-01

    This paper documents the results of research done under the auspices of the Nuclear Regulatory Commission Nuclear Plant Aging Research Program. It examines the degradation imparted to safety related Auxiliary Feedwater System pumps at nuclear plants due to the low flow operation. The Auxiliary Feedwater (AFW) System is normally a stand-by system. As such it is operated most often in the test mode. Since few plants are equipped with full flow test loops, most testing is accomplished at minimum flow conditions in pump by-pass lines. It is the vibration and hydraulic forces generated at low flow conditions that have been shown to be the major causes of AFW pump aging and degradation. The wear can be manifested in a number of ways, such as impeller or diffuser breakage, thrust bearing and/or balance device failure due to excessive loading, cavitation damage on such stage impellers, increase seal leakage or failure, sear injection piping failure, shaft or coupling breakage, and rotating element seizure

  18. Aging and low-flow degradation of auxiliary feedwater pumps

    International Nuclear Information System (INIS)

    Adams, M.L.

    1991-01-01

    This paper documents the results of research done under the auspices of the Nuclear Regulatory Commission Nuclear Plant Aging Research Program. It examines the degradation imparted to safety Auxiliary Feedwater System pumps at nuclear plants due to the low flow operation. The Auxiliary Feedwater (AFW) System is normally a stand-by system. As such it is operated most often in the test mode. Since few plants are equipped with full flow test loops, most testing is accomplished at minimum flow conditions in pump by-pass lines. It is the vibration and hydraulic forces generated at low flow conditions that have been shown to be the major causes of AFW pump aging and degradation. The wear can be manifested in a number of ways, such as impeller or diffuser breakage, thrust bearing and/or balance device failure due to excessive loading, cavitation damage on such stage impellers, increase seal leakage or failure, sear injection piping failure, shaft or coupling breakage, and rotating element seizure

  19. Age-related degradation of Westinghouse 480-volt circuit breakers

    International Nuclear Information System (INIS)

    Subudhi, M.; MacDougall, E.; Kochis, S.; Wilhelm, W.; Lee, B.S.

    1990-11-01

    After the McGuire event in 1987 relating to failure of the center pole weld in one of its reactor trip breakers, activities were initiated by the NRC to investigate the probable causes. A review of operating experience suggested that the burning of coils, jamming of the operating mechanism, and deterioration of the contacts dominated the breakers failures. Although failures of the pole shaft weld were not included as one of the generic problems, the NRC augmented inspection team had suspected that these welds were substandard which led them to crack prematurely. A DS-416 low voltage air circuit breaker manufactured by Westinghouse was mechanically cycled to identify age-related degradations. This accelerated aging test was conducted for over 36,000 cycles during nine months. Three separate pole shafts, one with a 60 degree weld, one with a 120 degree and one with a 180 degree were used to characterize the cracking in the pole level welds. In addition, three different operating mechanisms and several other parts were replaced as they became inoperable. The testing yielded many useful results. The burning of the closing coils was found to be the effect of binding in the linkages that are connected to this device. Among the seven welds on the pole shaft, number-sign 1 and number-sign 3 were the critical ones which cracked first to cause misalignment of the pole levers, which, in turn, had led to many problems with the operating mechanism including the burning of coils, excessive wear in certain parts, and overstressed linkages. Based on these findings, a maintenance program is suggested to alleviate the age-related degradations that occur due to mechanical cycling of this type of breaker. 3 refs., 39 figs., 7 tabs

  20. Product analysis for polyethylene degradation by radiation and thermal ageing

    International Nuclear Information System (INIS)

    Sugimoto, Masaki; Shimada, Akihiko; Kudoh, Hisaaki; Tamura, Kiyotoshi; Seguchi, Tadao

    2013-01-01

    The oxidation products in crosslinked polyethylene for cable insulation formed during thermal and radiation ageing were analyzed by FTIR-ATR. The products were composed of carboxylic acid, carboxylic ester, and carboxylic anhydride for all ageing conditions. The relative yields of carboxylic ester and carboxylic anhydride increased with an increase of temperature for radiation and thermal ageing. The carboxylic acid was the primary oxidation product and the ester and anhydride were secondary products formed by the thermally induced reactions of the carboxylic acids. The carboxylic acid could be produced by chain scission at any temperature followed by the oxidation of the free radicals formed in the polyethylene. The results of the analysis led to formulation of a new oxidation mechanism which was different from the chain reactions via peroxy radicals and peroxides. - Highlights: ► Products analysis of polyethylene degradation by radiation and thermal ageing. ► Components of carbonyl compounds produced in polyethylene by thermal and radiation oxidation were determined by FTIR. ► Carbonyl compounds comprised carboxylic acid, carboxylic ester, and carboxylic anhydride. ► Carboxylic acid was the primary oxidation product of chain scission at any oxidation temperature. ► Carboxylic ester and carboxylic anhydride are secondary products formed from carboxylic acid at higher temperature.

  1. Final Report Inspection of Aged/Degraded Containments Program.

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL; Ellingwood, B R [Georgia Institute of Technology; Oland, C Barry [ORNL

    2005-09-01

    The Inspection of Aged/Degraded Containments Program had primary objectives of (1) understanding the significant factors relating corrosion occurrence, efficacy of inspection, and structural capacity reduction of steel containments and liners of reinforced concrete containments; (2) providing the United States Nuclear Regulatory Commission (USNRC) reviewers a means of establishing current structural capacity margins or estimating future residual structural capacity margins for steel containments, and concrete containments as limited by liner integrity; (3) providing recommendations, as appropriate, on information to be requested of licensees for guidance that could be utilized by USNRC reviewers in assessing the seriousness of reported incidences of containment degradation; and (4) providing technical assistance to the USNRC (as requested) related to concrete technology. Primary program accomplishments have included development of a degradation assessment methodology; reviews of techniques and methods for inspection and repair of containment metallic pressure boundaries; evaluation of high-frequency acoustic imaging, magnetostrictive sensor, electromagnetic acoustic transducer, and multimode guided plate wave technologies for inspection of inaccessible regions of containment metallic pressure boundaries; development of a continuum damage mechanics-based approach for structural deterioration; establishment of a methodology for reliability-based condition assessments of steel containments and liners; and fragility assessments of steel containments with localized corrosion. In addition, data and information assembled under this program has been transferred to the technical community through review meetings and briefings, national and international conference participation, technical committee involvement, and publications of reports and journal articles. Appendix A provides a listing of program reports, papers, and publications; and Appendix B contains a listing of

  2. Seismic response of base isolated auxiliary building with age related degradation

    International Nuclear Information System (INIS)

    Park, Jun Hee; Choun, Young Sun; Choi, In Kil

    2012-01-01

    The aging of an isolator affects not only the mechanical properties of the isolator but also the dynamic properties of the upper structure, such as the change in stiffness, deformation capacity, load bearing capacity, creep, and damping. Therefore, the seismic response of base isolated structures will change with time. The floor response in the base isolated nuclear power plants (NPPs) can be particularly changed because of the change in stiffness and damping for the isolator. The increased seismic response due to the aging of isolator can cause mechanical problems for many equipment located in the NPPs. Therefore, it is necessary to evaluate the seismic response of base isolated NPPs with age related degradation. In this study, the seismic responses for a base isolated auxiliary building of SHIN KORI 3 and 4 with age related degradation were investigated using a nonlinear time history analysis. Floor response spectrums (FRS) were presented with time for identifying the change in seismic demand under the aging of isolator

  3. Auxiliary feedwater system aging study

    International Nuclear Information System (INIS)

    Kueck, J.D.

    1993-07-01

    This report documents the results of a Phase I follow-on study of the Auxiliary Feedwater (AFW) System that has been conducted for the US Regulatory Commission's Nuclear Plant Aging research Program. The Phase I study found a number of significant AFW System functions that are not being adequately tested by conventional test methods and some that are actually being degraded by conventional testing. Thus, it was decided that this follow-on study would focus on these testing omissions nd equipment degradation. The deficiencies in current monitoring and operating practice are categorized and evaluated. Areas of component degradation caused by current practice are discussed. Recommendations are made for improved diagnostic methods and test procedures

  4. Seismic Fragility Analysis of a Condensate Storage Tank with Age-Related Degradations

    Energy Technology Data Exchange (ETDEWEB)

    Nie, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Braverman, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hofmayer, C [Brookhaven National Lab. (BNL), Upton, NY (United States); Choun, Y-S [Brookhaven National Lab. (BNL), Upton, NY (United States); Kim, MK [Brookhaven National Lab. (BNL), Upton, NY (United States); Choi, I-K [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2011-04-01

    The Korea Atomic Energy Research Institute (KAERI) is conducting a five-year research project to develop a realistic seismic risk evaluation system which includes the consideration of aging of structures and components in nuclear power plants (NPPs). The KAERI research project includes three specific areas that are essential to seismic probabilistic risk assessment (PRA): (1) probabilistic seismic hazard analysis, (2) seismic fragility analysis including the effects of aging, and (3) a plant seismic risk analysis. Since 2007, Brookhaven National Laboratory (BNL) has entered into a collaboration agreement with KAERI to support its development of seismic capability evaluation technology for degraded structures and components. The collaborative research effort is intended to continue over a five year period. The goal of this collaboration endeavor is to assist KAERI to develop seismic fragility analysis methods that consider the potential effects of age-related degradation of structures, systems, and components (SSCs). The research results of this multi-year collaboration will be utilized as input to seismic PRAs. This report describes the research effort performed by BNL for the Year 4 scope of work. This report was developed as an update to the Year 3 report by incorporating a major supplement to the Year 3 fragility analysis. In the Year 4 research scope, an additional study was carried out to consider an additional degradation scenario, in which the three basic degradation scenarios, i.e., degraded tank shell, degraded anchor bolts, and cracked anchorage concrete, are combined in a non-perfect correlation manner. A representative operational water level is used for this effort. Building on the same CDFM procedure implemented for the Year 3 Tasks, a simulation method was applied using optimum Latin Hypercube samples to characterize the deterioration behavior of the fragility capacity as a function of age-related degradations. The results are summarized in Section 5

  5. Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar Cell due to Ageing

    Directory of Open Access Journals (Sweden)

    Parth Bhatt

    2016-01-01

    Full Text Available This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs. The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V characteristics are analyzed. Short circuit current density (JSC decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS. An increase in net resistance results in a lower JSC for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degraded DSC. It is also confirmed from EIS that the degradation leads to a better contact formation between the electrolyte and Pt electrode, which improves the fill factor of the DSC. But the recombination throughout the DSC is found to increase along with degradation. This study suggests that the DSC should be used under low illumination conditions and around room temperature for a longer life.

  6. A study of the effect of maintenance on the safety of a mechanical system subject to aging and its application to steam generator tube degradation

    International Nuclear Information System (INIS)

    Dussarte, D.

    1991-11-01

    The different degradation mechanisms to which pressurized water reactor steam generator tubes are observed to be subject may result in the risk of their rupture being greater than anticipated. Prevention of tube rupture essentially consists of inspections during outages of the units and applying appropriate criteria for the withdrawal of defective tubes from service. Planning such measures implies being able to gauge the effectiveness of the action taken. This document describes a proposed technique for quantifying the effects of the preventive maintenance we have had to develop to address this problem and, hence, to obtain material for assessing the action taken by the utility. (author)

  7. Degradability of aged aquatic suspensions of C60 nanoparticles

    DEFF Research Database (Denmark)

    Hartmann, Nanna Isabella Bloch; Buendia, Inmaculada M.; Bak, Jimmy

    2011-01-01

    In this study, aged aqueous suspensions of C(60) (nC(60)) were investigated in the respirometric OECD test for ready biodegradability. Two suspensions of nC(60) were prepared by stirring and aged under indirect exposure to sunlight for 36 months. ATR-FTIR analyses confirmed the presence of C(60)-...

  8. Age-Related Degradation of Nuclear Power Plant Structures and Components

    International Nuclear Information System (INIS)

    Braverman, J.; Chang, T.-Y.; Chokshi, N.; Hofmayer, C.; Morante, R.; Shteyngart, S.

    1999-01-01

    This paper summarizes and highlights the results of the initial phase of a research project on the assessment of aged and degraded structures and components important to the safe operation of nuclear power plants (NPPs). A review of age-related degradation of structures and passive components at NPPs was performed. Instances of age-related degradation have been collected and reviewed. Data were collected from plant generated documents such as Licensing Event Reports, NRC generic communications, NUREGs and industry reports. Applicable cases of degradation occurrences were reviewed and then entered into a computerized database. The results obtained from the review of degradation occurrences are summarized and discussed. Various trending analyses were performed to identify which structures and components are most affected, whether degradation occurrences are worsening, and what was the most common aging mechanisms. The paper also discusses potential aging issues and degradation-susceptible structures and passive components which would have the greatest impact on plant risk

  9. Aging effect on radiation-induced degradation of polypropylene

    International Nuclear Information System (INIS)

    Imai, M.; Sekiguchi, M.; Tabei, M.; Yamada, Y.; Shimizu, H.

    1995-01-01

    PP sheets and films were irradiated with γ-ray and with high energy electron beam. The mechanical degradation, decay of peroxy radical and the variation of molecular weight with storage time were measured. The variation of molecular weight corresponded to mechanical degradation. The molecular weight of sheet sample at which elongation falls to zero was much higher than that of film sample. The relation between mechanical degradation and sample thickness was discussed. (author)

  10. PVT Degradation Studies: Acoustic Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Dib, Gerges [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tucker, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-04-01

    Under certain environmental conditions, polyvinyl toluene (PVT) plastic scintillator has been observed to undergo internal fogging. This document reports on a study of acoustic techniques to determine whether they can provide a diagnostic for the fogging of PVT. Different ultrasound techniques were employed for detecting the level of internal fogging in PVT, including wave velocity measurements, attenuation, nonlinear acoustics, and acoustic microscopy. The results indicate that there are linear relations between the wave velocity and wave attenuation with the level of internal fogging. The effects of fogging on ultrasound wave attenuation is further verified by acoustic microscopy imaging, where regions with fog in the specimen demonstration higher levels of attenuation compared to clear regions. Results from the nonlinear ultrasound measurements were inconclusive due to high sensitivities to transducer coupling and fixture variabilities.

  11. Materials ageing degradation programme in japan and proactive ageing management in NPP

    International Nuclear Information System (INIS)

    Shoji, T.

    2013-01-01

    Predictive and preventive maintenance technologies are increasingly of importance for the long term operation (LTO) of Light Water Reactor (LWR) plants. In order for the realization LTO to be successful, it is essential that aging degradation phenomena should be properly managed by using adequate maintenance programs based on foreseeing the aging phenomena and evaluating their rates of development, where Nuclear Power Plants can be continued to operate beyond the original design life depending upon the regulatory authority rules. In combination with Periodic Safety Review (PSR) and adequate maintenance program, a plant life can be extended to 60 years or more. Plant Life Management (PLiM) is based upon various maintenance program as well as systematic safety review updated based upon the state of the art of science and technology. One of the potential life time limiting issue would be materials ageing degradation and therefore an extensive efforts have been paid world-widely. In 2007, NISA launched a national program on Enhanced Ageing Management Program and 4 nationwide clusters were formed to carry out the national program where materials ageing degradation was one of the major topics. In addition to these degradation modes, one important activities in this program is proactive materials degradation management directed by the author which is a kind of the extension program of NRC PMDA program based upon more fundamental approach by a systematic elicitation by the experts nominated from all over the world. NISA program can be divided into two phases, one is from fiscal years (FY) 2006 - 2010 and the other FY 2011. Later phase is focusing more on System Safety due to Fukushima NPP accident. The main objectives of the Phase I is to evaluate potential and complex degradation phenomena and their mechanisms in order to identify future risks of component aging in nuclear power plants. The following items are of particular concern in this phase: (a) investigation of

  12. 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

  13. 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

  14. 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.

  15. Identification and Assessment of Recent Aging-Related Degradation Occurrences in U.S. Nuclear Power Plants

    International Nuclear Information System (INIS)

    Choi, In Kil; Kim, Min Kyu; Choun, Young Sun; Hofmayer, Charles; Braverman, Joseph; Nie, Jinsou

    2008-11-01

    This report describes the research effort performed by BNL for the Year 1 scope of work. This research focused on collecting and reviewing degradation occurrences in US NPPs and identifying important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, this report provides a description of current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. Finally, this report provides the conclusions reached from this research effort, which includes a summary of the findings from the identification and evaluation effort of degradation occurrences, an assessment of the degradation trending results, and insights into the important aging characteristics that should be considered in the tasks to be performed in the Year 2 through 5 research effort

  16. Age Replacement and Service Rate Control of Stochastically Degrading Queues

    National Research Council Canada - National Science Library

    Chapin, Patrick

    2004-01-01

    This thesis considers the problem of optimally selecting a periodic replacement time for a multiserver queueing system in which each server is subject to degradation as a function of the mean service...

  17. Canadian programs on understanding and managing aging degradation of nuclear power plant components

    International Nuclear Information System (INIS)

    Chadha, J.A.; Pachner, J.

    1989-06-01

    Maintaining adequate safety and reliability of nuclear power plants and nuclear power plant life assurance and life extension are growing in importance as nuclear plants get older. Age-related degradation of plant components is complex and not fully understood. This paper provides an overview of the Canadian approach and the main activities and their results towards understanding and managing age-related degradation of nuclear power plant components, structures and systems. A number of pro-active programs have been initiated to anticipate, detect and mitigate potential aging degradation at an early stage before any serious impact on plant safety and reliability. These programs include Operational Safety Management Program, Nuclear Plant Life Assurance Program, systematic plant condition assessment, refurbishment and upgrading, post-service examination and testing, equipment qualification, research and development, and participation in the IAEA programs on safety aspects of nuclear power plant aging and life extension. A regulatory policy on nuclear power plants is under development and will be based on the domestic as well as foreign and international studies and experience

  18. Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications*

    Science.gov (United States)

    Panwar, Preety; Lamour, Guillaume; Mackenzie, Neil C. W.; Yang, Heejae; Ko, Frank; Li, Hongbin; Brömme, Dieter

    2015-01-01

    During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging. PMID:26224630

  19. Cellular degradation activity is maintained during aging in long-living queen bees.

    Science.gov (United States)

    Hsu, Chin-Yuan; Qiu, Jiantai Timothy; Chan, Yu-Pei

    2016-11-01

    Queen honeybees (Apis mellifera) have a much longer lifespan than worker bees. Whether cellular degradation activity is involved in the longevity of queen bees is unknown. In the present study, cellular degradation activity was evaluated in the trophocytes and oenocytes of young and old queen bees. The results indicated that (i) 20S proteasome activity and the size of autophagic vacuoles decreased with aging, and (ii) there were no significant differences between young and old queen bees with regard to 20S proteasome expression or efficiency, polyubiquitin aggregate expression, microtubule-associated protein 1 light chain 3-II (LC3-II) expression, 70 kDa heat shock cognate protein (Hsc70) expression, the density of autophagic vacuoles, p62/SQSTM1 expression, the activity or density of lysosomes, or molecular target of rapamycin expression. These results indicate that cellular degradation activity maintains a youthful status in the trophocytes and oenocytes of queen bees during aging and that cellular degradation activity is involved in maintaining the longevity of queen bees.

  20. Delaying aging and the aging-associated decline in protein homeostasis by inhibition of tryptophan degradation

    Science.gov (United States)

    van der Goot, Annemieke T.; Zhu, Wentao; Vázquez-Manrique, Rafael P.; Seinstra, Renée I.; Dettmer, Katja; Michels, Helen; Farina, Francesca; Krijnen, Jasper; Melki, Ronald; Buijsman, Rogier C.; Ruiz Silva, Mariana; Thijssen, Karen L.; Kema, Ido P.; Neri, Christian; Oefner, Peter J.; Nollen, Ellen A. A.

    2012-01-01

    Toxicity of aggregation-prone proteins is thought to play an important role in aging and age-related neurological diseases like Parkinson and Alzheimer’s diseases. Here, we identify tryptophan 2,3-dioxygenase (tdo-2), the first enzyme in the kynurenine pathway of tryptophan degradation, as a metabolic regulator of age-related α-synuclein toxicity in a Caenorhabditis elegans model. Depletion of tdo-2 also suppresses toxicity of other heterologous aggregation-prone proteins, including amyloid-β and polyglutamine proteins, and endogenous metastable proteins that are sensors of normal protein homeostasis. This finding suggests that tdo-2 functions as a general regulator of protein homeostasis. Analysis of metabolite levels in C. elegans strains with mutations in enzymes that act downstream of tdo-2 indicates that this suppression of toxicity is independent of downstream metabolites in the kynurenine pathway. Depletion of tdo-2 increases tryptophan levels, and feeding worms with extra l-tryptophan also suppresses toxicity, suggesting that tdo-2 regulates proteotoxicity through tryptophan. Depletion of tdo-2 extends lifespan in these worms. Together, these results implicate tdo-2 as a metabolic switch of age-related protein homeostasis and lifespan. With TDO and Indoleamine 2,3-dioxygenase as evolutionarily conserved human orthologs of TDO-2, intervening with tryptophan metabolism may offer avenues to reducing proteotoxicity in aging and age-related diseases. PMID:22927396

  1. Degradability of aged aquatic suspensions of C60 nanoparticles

    DEFF Research Database (Denmark)

    Hartmann, B.; Buendia, Inmaculada M.; Baun, Anders

    2011-01-01

    While studies of the potential human and environmental effects of C60 and its derivatives are emerging in the scientific literature, the environmental fate of C60 is still largely unknown. In this study, aged aqueous suspensions of C60 (nC60) were investigated in the respirometric OECD test...... for ready biodegradability. Two suspensions of nC60 were prepared by stirring and aged under indirect exposure to sunlight for 36 months, which resulted in relatively stable suspensions with a dark-brown colour. The suspended nC60 could not be extracted into toluene and indicating that the particles were...... no longer present as underivatised nC60 but had undergone a transformation. TEM images and particle tracking analysis showed that the suspension consisted of particle aggregates with a size of 156 nm (SD=54nm) and 139nm (Sd=49), respectively, but also contained smaller aggregates. Samples of the nC60...

  2. 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.

  3. Identification of CSSC Caused by Aging and Degradation

    International Nuclear Information System (INIS)

    Florescu, Gheorghe; Cojan, Mihail

    2006-01-01

    PSA studies, that were developed for some NPPs, permit the using of the created models to perform many research tests, in order to optimize the structures, systems and components (SSCs) operation or to identify the NPP or systems weaknesses, due to specific or special factors. SSCs that influence decisively the NPP reliability are considered as critical. Also, for the accident conditions, the SSC, which have a major influence to the system availability or operability, are considered as critical. Many worldwide NPPs reached the life time or are very close to do that. Several SSCs have shorter life times than NPP's life time. Ageing is one of the factors that decrease the SSC life time. Due to ageing, if are not replaced, some SSCs, or groups of redundant SSCs, become critical looking to safety. Some questions for what to do in the situation when a SSC must be replaced and the SSC specific manufacturer does not exist, could also be put. The paper tried to solve the problem of SSC modeling by introducing of an ageing factor in SSC model. Fault tree (F/T) modeling approach is assumed. There are two possibilities for modeling: failure rates that are changed or specific MCS. (authors)

  4. Overview of the age-related degradation of nuclear power plant structures

    International Nuclear Information System (INIS)

    Deng, Daniel

    2004-01-01

    License renewal of nuclear power plants is an issue of increasing interest to the U.S. nuclear industry and the U.S. NRC. This paper presents and evaluates the plausible age-related degradation mechanisms that may affect the concrete and steel containment structures and other Class I structures to continue to perform their safety functions. Preventive and/or mitigative options are outlined for managing degradation mechanisms that could significantly affect plant performance during the license renewal period. The provided technical information and the degradation management options may be used as references for comparison with plant specific conditions to ensure that age-related degradation is controlled during the license renewal term. Plausible degradation mechanisms described and analyzed as they may affect the concrete, reinforcing steel, containment steel shell, prestressed-tendon, steel liner and other structural components typically used in Class I structures. The significance of these age-related degradation mechanisms to the structural components are evaluated, giving consideration to the design basis and quality of construction; typical service conditions; operating and maintenance history; and current test, inspection and refurbishment practices for containment and Class I structures. Degradation mechanisms which cannot be generically dispositioned on the basis of the two-step approach: (1) they will not cause significant degradation, or (2) any potential degradation will be bounded by current test, inspection, analytical evaluation, and/or refurbishment programs are identified. Aging degradation management measures are recommended to address the remaining age-related degradation mechanisms. A three-phase approach for the management of the containment and Class I structures is introduced. Various techniques, testing tools and the acceptable criteria for each step of the evaluation of the structures status are provided. The preventive and mitigative

  5. Viscometric studies of chitosan radiation degradation

    International Nuclear Information System (INIS)

    Rapado, M.; Ceausoglu, I.; Hunkeler, D.

    2001-01-01

    The paper presents the preliminary results, related to the viscometric studies on chitosan gamma radiation degradation. To follow the effects on the processes of chitosan transformations caused by irradiation in vacuum irradiated solutions changes of viscosity, and viscosity average molecular weight were measured The influence of absorbed dose on the chitosan molecular weight was studied using the Mark-Houwink-Sakurada equation. Various relationships for the for the determination of the intrinsic viscosity were made vias the Huggins, Kramer and Schulz- Blaschke models. The distinct decrease of intrinsic viscosity indicates that the main change scission was the dominating process

  6. Non-Destructive Analysis of Degradation Mechanisms in Cycle-Aged Graphite/LiCoO2 Batteries

    Directory of Open Access Journals (Sweden)

    Liqiang Zhang

    2014-09-01

    Full Text Available Non-destructive analysis of degradation mechanisms can be very beneficial for the prognostics and health management (PHM study of lithium-ion batteries. In this paper, a type of graphite/LiCoO2 battery was cycle aged at high ambient temperature, then 25 parameters of the multi-physics model were identified. Nine key parameters degraded with the cycle life, and they were treated as indicators of battery degradation. Accordingly, the degradation mechanism was discussed by using the multi-physics model and key parameters, and the reasons for capacity fade and the internal resistance increase were analyzed in detail. All evidence indicates that the formation reaction of the solid electrolyte interface (SEI film is the main cause of battery degradation at high ambient temperature.

  7. Ageing degradation mechanisms in nuclear power plants: lessons learned from operating experience

    International Nuclear Information System (INIS)

    Bieth, M.; Zerger, B.; Duchac, A.

    2014-01-01

    This paper presents main results of a comprehensive study performed by the European Clearinghouse on Operating Experience Feedback of Nuclear Power Plants (NPP) with the support of IRSN (Institut de Surete Nucleaire et de Radioprotection) and GRS (Gesellschaft fuer Anlagen und Reaktorsicherheit mbH). Physical ageing mechanisms of Structures, Systems and Components (SSC) that eventually lead to ageing related systems and components failures at nuclear power plants were the main focus of this study. The analysis of ageing related events involved operating experience reported by NPP operators in France, Germany, USA and to the IAEA/NEA International Reporting System on operating experience for the past 20 years. A list of relevant ageing related events was populated. Each ageing related event contained in the list was analyzed and results of analysis were summarized for each ageing degradation mechanism which appeared to be the dominant contributor or direct cause. This paper provides insights into ageing related operating experience as well as recommendations to deal with the physical ageing of nuclear power plant SSC important to safety. (authors)

  8. Parylene C Aging Studies.

    Energy Technology Data Exchange (ETDEWEB)

    Achyuthan, Komandoor; Sawyer, Patricia Sue.; Mata, Guillermo Adrian; White II, Gregory Von; Bernstein, Robert

    2014-09-01

    Parylene C is used in a device because of its conformable deposition and other advantages. Techniques to study Parylene C aging were developed, and "lessons learned" that could be utilized for future studies are the result of this initial study. Differential Scanning Calorimetry yielded temperature ranges for Parylene C aging as well as post-deposition treatment. Post-deposition techniques are suggested to improve Parylene C performance. Sample preparation was critical to aging regimen. Short-term (%7E40 days) aging experiments with free standing and ceramic-supported Parylene C films highlighted "lessons learned" which stressed further investigations in order to refine sample preparation (film thickness, single sided uniform coating, machine versus laser cutting, annealing time, temperature) and testing issues ("necking") for robust accelerated aging of Parylene C.

  9. Study of PP/montmorillonite composite degradation

    International Nuclear Information System (INIS)

    Baer, Marcia; Granado, Carlos J.F.

    2009-01-01

    The objective of this work was to produce composites of PP/sodium bentonite and PP/ organophilic bentonite through melt intercalation and analyze the degradation produced by ultraviolet irradiation. The XRD results showed that the samples of nature bentonite had better interaction with de polymer and produced intercalated nanocomposite. The effect of UV irradiation on degradation was observed after 24 hours of exposition. The samples showed the same photoproducts and at the same proportion until 240 hours of UV exposition; with 480 hours the organophilize bentonite composite showed higher degradation than other ones. The superficial cracks increased with degradation time. The degradation occurs due chromophores impurities presented in the samples, thus samples with sodium clay show higher degradation, and organophilic clay contains ammonium salt that contribute to increase the degradation. (author)

  10. Advanced Cell Development and Degradation Studies

    International Nuclear Information System (INIS)

    O'Brien, J.E.; Stoots, C.M.; Herring, J.S.; O'Brien, R.C.; Condie, K.G.; Sohal, M.; Housley, G.K.; Hartvigsen, J.J.; Larsen, D.; Tao, G.; Yildiz, B.; Sharma, V.; Singh, P.; Petigny, N.; Cable, T.L.

    2010-01-01

    The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells for large-scale hydrogen production from steam over a temperature range of 800 to 900 C. From 2003-2009, this work was sponsored by the DOE Nuclear Hydrogen Initiative (NHI). Starting in 2010, the HTE research program has been sponsored by the Next Generation Nuclear Plant (NGNP) program. HTSE research priorities in FY10 are centered on understanding and reducing cell and stack performance degradation to an acceptable level to advance the technology readiness level of HTSE and to justify further large-scale demonstration activities. This report provides a summary of our FY10 experimental program, which has been focused on advanced cell and stack development and degradation studies. Advanced cell and stack development activities are under way at five technology partners: MSRI, Versa Power, Ceramatec, NASA Glenn, and St. Gobain. Performance evaluation of the advanced technology cells and stacks has been performed by the technology partners, by MIT and the University of Connecticut and at the INL HTE Laboratory. Summaries of these development activities and test results are presented.

  11. Advanced Cell Development and Degradation Studies

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots; J. S. Herring; R. C. O' Brien; K. G. Condie; M. Sohal; G. K. Housley; J. J. Hartvigsen; D. Larsen; G. Tao; B. Yildiz; V. Sharma; P. Singh; N. Petigny; T. L. Cable

    2010-09-01

    The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells for large-scale hydrogen production from steam over a temperature range of 800 to 900ºC. From 2003 – 2009, this work was sponsored by the DOE Nuclear Hydrogen Initiative (NHI). Starting in 2010, the HTE research program has been sponsored by the Next Generation Nuclear Plant (NGNP) program. HTSE research priorities in FY10 are centered on understanding and reducing cell and stack performance degradation to an acceptable level to advance the technology readiness level of HTSE and to justify further large-scale demonstration activities. This report provides a summary of our FY10 experimental program, which has been focused on advanced cell and stack development and degradation studies. Advanced cell and stack development activities are under way at five technology partners: MSRI, Versa Power, Ceramatec, NASA Glenn, and St. Gobain. Performance evaluation of the advanced technology cells and stacks has been performed by the technology partners, by MIT and the University of Connecticut and at the INL HTE Laboratory. Summaries of these development activities and test results are presented.

  12. Studies on degradation of chlorinated aromatic hydrocarbon by ...

    African Journals Online (AJOL)

    SERVER

    2007-06-04

    Jun 4, 2007 ... chlorobenzene to study the kinetics of degradation of chlorobenzene. The rate of decomposition of ... hydraulic fluids, biocides, herbicides, plastics, degree- ..... degradation by bacteria isolated from contaminated groundwater.

  13. 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)

  14. Durability Improvements Through Degradation Mechanism Studies

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mukundan, Rangachary [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Spernjak, Dusan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baker, Andrew M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lujan, Roger W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Langlois, David Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ahluwalia, Rajesh [Argonne National Lab. (ANL), Argonne, IL (United States); Papadia, D. D. [Argonne National Lab. (ANL), Argonne, IL (United States); Weber, Adam Z. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kusoglu, Ahmet [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shi, Shouwnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); More, K. L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Grot, Steve [Ion Power, New Castle, DE (United States)

    2015-08-03

    The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. By investigating cell component degradation modes and defining the fundamental degradation mechanisms of components and component interactions, new materials can be designed to improve durability. To achieve a deeper understanding of PEM fuel cell durability and component degradation mechanisms, we utilize a multi-institutional and multi-disciplinary team with significant experience investigating these phenomena.

  15. The Study of the Microbes Degraded Polystyrene

    Directory of Open Access Journals (Sweden)

    Zhi-Long Tang

    2017-01-01

    Full Text Available Under the observation that Tenebrio molitor and Zophobas morio could eat polystyrene (PS, we setup the platform to screen the gut microbes of these two worms. To take advantage of that Tenebrio molitor and Zophobas morio can eat and digest polystyrene as its diet, we analyzed these special microbes with PS plate and PS turbidity system with time courses. There were two strains TM1 and ZM1 which isolated from Tenebrio molitor and Zophobas morio, and were identified by 16S rDNA sequencing. The results showed that TM1 and ZM1 were cocci-like and short rod shape Gram-negative bacteria under microscope. The PS plate and turbidity assay showed that TM1 and ZM1 could utilize polystyrene as their carbon sources. The further study of PS degraded enzyme and cloning warrants our attention that this platform will be an excellent tools to explore and solve this problem.

  16. Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

    Science.gov (United States)

    Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

    2017-07-01

    Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

  17. Evaluation of the effect of organic pro-degradant concentration in polypropylene exposed to the natural ageing

    Energy Technology Data Exchange (ETDEWEB)

    Montagna, L. S., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Catto, A. L., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Rossini, K., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Forte, M. M. C., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br; Santana, R. M. C., E-mail: larissambiental@yahoo.com.br, E-mail: andrecatto@terra.com.br, E-mail: katiandry@hotmail.com, E-mail: mmcforte@hotmail.com, E-mail: ruth.santana@ufrgs.br [Engineering School/Laboratory of Polymeric Materials, Federal University of Rio Grande do Sul, Porto Alegre (Brazil)

    2014-05-15

    The production and consumption of plastics in the last decade has recorded a remarkable increase in the scientific and industrial interest in environmentally degradable polymer (EDPs). Polymers wastes are deposited improperly, such as dumps, landfills, rivers and seas, causing a serious problem by the accumulation in the environment. The abiotic processes, like the photodegradation, are the most efficient occurring in the open environmental, where the polymers undergo degradation from the action of sunlight that result from direct exposure to solar radiation, however depend of the type of chemical ageing, which is the principal component of climatic ageing. The subject of this work is to study the influence of concentration of organic pro-degradant (1, 2 and 3 % w/w) in the polypropylene (PP) exposed in natural ageing. PP samples with and without the additive were processed in plates square form, obtained by thermal compression molding (TCM) using a press at 200°C under 2 tons for 5 min, and then were exposed at natural ageing during 120 days. The presence of organic additive influenced on PP degradability, this fact was assessed by changes in the thermal and morphology properties of the samples after 120 days of natural ageing. Scanning Electronic Microscopy (SEM) results of the morphological surface of the modified PP samples showed greater degradation photochemical oxidative when compared to neat PP, due to increase of rugosity and formation of microvoids. PP samples with different pro-degradant concentration under natural ageing presented a degree of crystallinity, obtained by Differential Scanning Calorimeter (DSC) increases in comparing the neat PP.

  18. Study of SEY degradation of amorphous carbon coatings

    CERN Document Server

    Bundaleski, N.; Santos, A.; Teodoro, O.M.N.D.; Silva, A.G.

    2013-04-22

    Deposition of low secondary electron yield (SEY) carbon coatings by magnetron sputtering onto the inner walls of the accelerator seems to be the most promising solution for suppressing the electron cloud problem. However, these coatings change their electron emission properties during long term exposure to air. The ageing process of carbon coated samples with initial SEY of about 0.9 received from CERN is studied as a function of exposure to different environments. It is shown that samples having the same initial SEY may age with different rates. The SEY increase can be correlated with the surface concentration of oxygen. Annealing of samples in air at 100-200 {\\deg}C reduces the ageing rate and even recovers previously degraded samples. The result of annealing is reduction of the hydrogen content in the coatings by triggering its surface segregation followed by desorption.

  19. 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

  20. ESR studies on degradation processes in polyethyleneterephtalate

    International Nuclear Information System (INIS)

    Chipara, M.; Chipara, M.D.; Georgescu, L.; Constantinescu, L.; Morosanu, C.

    2002-01-01

    Complete text of publication follows. The generation of free radicals by degradation processes (thermal, plasma and radiation induced) is analyzed. Details regarding the generation of free radicals, their interactions, and kinetics, as revealed by electron spin resonance (ESR), with emphasis on laser beam degradation, are discussed. Some ESR lines of laser-irradiated polyethyleneterephtalate (PET), recorded at room temperature, are shown in Figure 1. The lines are narrow singlets located around g=2.003. The resonance line amplitude, width and double integral of the resonance line are affected by the power of the incident beam. The common features of these degradation processes (universal behavior) as well as the fingerprints of each degradation process are analyzed in detail

  1. Combining an Electrothermal and Impedance Aging Model to Investigate Thermal Degradation Caused by Fast Charging

    Directory of Open Access Journals (Sweden)

    Joris de Hoog

    2018-03-01

    Full Text Available Fast charging is an exciting topic in the field of electric and hybrid electric vehicles (EVs/HEVs. In order to achieve faster charging times, fast-charging applications involve high-current profiles which can lead to high cell temperature increase, and in some cases thermal runaways. There has been some research on the impact caused by fast-charging profiles. This research is mostly focused on the electrical, thermal and aging aspects of the cell individually, but these factors are never treated together. In this paper, the thermal progression of the lithium-ion battery under specific fast-charging profiles is investigated and modeled. The cell is a Lithium Nickel Manganese Cobalt Oxide/graphite-based cell (NMC rated at 20 Ah, and thermal images during fast-charging have been taken at four degradation states: 100%, 90%, 85%, and 80% State-of-Health (SoH. A semi-empirical resistance aging model is developed using gathered data from extensive cycling and calendar aging tests, which is coupled to an electrothermal model. This novel combined model achieves good agreement with the measurements, with simulation results always within 2 °C of the measured values. This study presents a modeling methodology that is usable to predict the potential temperature distribution for lithium-ion batteries (LiBs during fast-charging profiles at different aging states, which would be of benefit for Battery Management Systems (BMS in future thermal strategies.

  2. Degradations analysis and aging modeling for health assessment and prognostics of PEMFC

    International Nuclear Information System (INIS)

    Jouin, Marine; Gouriveau, Rafael; Hissel, Daniel; Péra, Marie-Cécile; Zerhouni, Noureddine

    2016-01-01

    Applying prognostics to Proton Exchange Membrane Fuel Cell (PEMFC) stacks is a good solution to help taking actions extending their lifetime. However, it requires a great understanding of the degradation mechanisms and failures occurring within the stack. This task is not simple when applied to a PEMFC due to the different levels (stack - cells - components), the different scales and the multiple causes that lead to degradation. To overcome this problem, this work proposes a methodology dedicated to the setting of a framework and a modeling of the aging for prognostics. This methodology is based on a deep literature review and degradation analyses of PEMFC stacks. This analysis allows defining a proper vocabulary dedicated to PEMFC's prognostics and health management and a clear limited framework to perform prognostics. Then the degradations review is used to select critical components within the stack, and to define their critical failure mechanisms thanks the proposal of new fault trees. The impact of these critical components and mechanisms on the power loss during aging is included to the model for prognostics. This model is finally validated on four datasets with different mission profiles both for health assessment and prognostics. - Highlights: • A proper framework to perform PHM, particularly prognostics, of PEMFC is proposed. • A degradation analysis is performed. • A completely new model of PEMFC degradation is proposed. • SOH estimation is performed with very high coefficients of determination.

  3. Study on the degradation of chitosan slurries

    Directory of Open Access Journals (Sweden)

    Benjamin Martini

    2016-01-01

    Full Text Available In the present work, we measured the degradation rate of different chitosan slurries. Several parameters were monitored such as temperature (25 °C, 37 °C, 50 °C; chitosan concentration (1% and 2% (w/V; and polymer molecular weight. The samples were tested in dynamic sweep test mode. This test is able to provide a reliable estimation of viscosity variations of the slurries; in turn, these variations could be related to degradation rate of the system in the considered conditions. The resulting information is particularly important especially in applications in which there is a close relationship between physical properties and molecular structure.

  4. Construction of Spectral Discoloration Model for Red Lead Pigment by Aging Test and Simulating Degradation Experiment

    Directory of Open Access Journals (Sweden)

    Jinxing Liang

    2016-01-01

    Full Text Available The construction of spectral discoloration model, based on aging test and simulating degradation experiment, was proposed to detect the aging degree of red lead pigment in ancient murals and to reproduce the spectral data supporting digital restoration of the ancient murals. The degradation process of red lead pigment under the aging test conditions was revealed by X-ray diffraction, scanning electron microscopy, and spectrophotometer. The simulating degradation experiment was carried out by proportionally mixing red lead and lead dioxide with referring to the results of aging test. The experimental result indicated that the pure red lead was gradually turned into black lead dioxide, and the amount of tiny particles of the aging sample increased faced with aging process. Both the chroma and lightness of red lead pigment decreased with discoloration, and its hue essentially remains unchanged. In addition, the spectral reflectance curves of the aging samples almost started rising at about 550 nm with the inflection moving slightly from about 570 nm to 550 nm. The spectral reflectance of samples in long- and in short-wavelength regions was fitted well with the logarithmic and linear function. The spectral discoloration model was established, and the real aging red lead pigment in Dunhuang murals was measured and verified the effectiveness of the model.

  5. Age Differences in Face Processing: The Role of Perceptual Degradation and Holistic Processing.

    Science.gov (United States)

    Boutet, Isabelle; Meinhardt-Injac, Bozana

    2018-01-24

    We simultaneously investigated the role of three hypotheses regarding age-related differences in face processing: perceptual degradation, impaired holistic processing, and an interaction between the two. Young adults (YA) aged 20-33-year olds, middle-age adults (MA) aged 50-64-year olds, and older adults (OA) aged 65-82-year olds were tested on the context congruency paradigm, which allows measurement of face-specific holistic processing across the life span (Meinhardt-Injac, Persike & Meinhardt, 2014. Acta Psychologica, 151, 155-163). Perceptual degradation was examined by measuring performance with faces that were not filtered (FSF), with faces filtered to preserve low spatial frequencies (LSF), and with faces filtered to preserve high spatial frequencies (HSF). We found that reducing perceptual signal strength had a greater impact on MA and OA for HSF faces, but not LSF faces. Context congruency effects were significant and of comparable magnitude across ages for FSF, LSF, and HSF faces. By using watches as control objects, we show that these holistic effects reflect face-specific mechanisms in all age groups. Our results support the perceptual degradation hypothesis for faces containing only HSF and suggest that holistic processing is preserved in aging even under conditions of reduced signal strength. © The Author(s) 2018. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Auxiliary feedwater system aging study

    International Nuclear Information System (INIS)

    Kueck, J.D.

    1992-01-01

    The Phase 1 Auxiliary Feedwater (AFW) System Aging Study, NUREG/CR-5404 V1, focused on how and to what extent the various AFW system component types fail, how the failures have been and can be detected, and on the value of current testing requirements and practices. This follow-on study, which will be provided in full in NUREG/CR-5404 V2, provides a closure to the Phase 1 Study. For each of the component types and for the various sources of component failure identified in the Phase 1 Study, the methods of failure detection were designated and tabulated and the following findings became evident: Instrumentation and Control (I and C) related failures dominated the group of failures that were detected during demand conditions; many of the potential failure sources not detectable by the current monitoring practices were related to the I and C portion of the system; some component failure modes are actually aggravated by conventional test methods; and several important system functions did not undergo any function verification test. The goal of this follow-on study was to categorize and evaluate the deficiencies in testing identified by Phase 1 and to make specific recommendations for corrective action. In addition, this study presents discussions of alternate, state-of-the-art test methods, and provides a proposed Auxiliary Feedwater Pump test at normal operating pressure which should do much to verify system operability while eliminating degradation

  7. Intraindividual variability in vigilance performance: does degrading visual stimuli mimic age-related "neural noise"?

    Science.gov (United States)

    MacDonald, Stuart W S; Hultsch, David F; Bunce, David

    2006-07-01

    Intraindividual performance variability, or inconsistency, has been shown to predict neurological status, physiological functioning, and age differences and declines in cognition. However, potential moderating factors of inconsistency are not well understood. The present investigation examined whether inconsistency in vigilance response latencies varied as a function of time-on-task and task demands by degrading visual stimuli in three separate conditions (10%, 20%, and 30%). Participants were 24 younger women aged 21 to 30 years (M = 24.04, SD = 2.51) and 23 older women aged 61 to 83 years (M = 68.70, SD = 6.38). A measure of within-person inconsistency, the intraindividual standard deviation (ISD), was computed for each individual across reaction time (RT) trials (3 blocks of 45 event trials) for each condition of the vigilance task. Greater inconsistency was observed with increasing stimulus degradation and age, even after controlling for group differences in mean RTs and physical condition. Further, older adults were more inconsistent than younger adults for similar degradation conditions, with ISD scores for younger adults in the 30% condition approximating estimates observed for older adults in the 10% condition. Finally, a measure of perceptual sensitivity shared increasing negative associations with ISDs, with this association further modulated as a function of age but to a lesser degree by degradation condition. Results support current hypotheses suggesting that inconsistency serves as a marker of neurological integrity and are discussed in terms of potential underlying mechanisms.

  8. Hypothalamic ER–associated degradation regulates POMC maturation, feeding, and age-associated obesity

    Science.gov (United States)

    Kim, Geun Hyang; Somlo, Diane R.M.; Haataja, Leena; Song, Soobin; Nillni, Eduardo A.

    2018-01-01

    Pro-opiomelanocortin (POMC) neurons function as key regulators of metabolism and physiology by releasing prohormone-derived neuropeptides with distinct biological activities. However, our understanding of early events in prohormone maturation in the ER remains incomplete. Highlighting the significance of this gap in knowledge, a single POMC cysteine-to-phenylalanine mutation at position 28 (POMC-C28F) is defective for ER processing and causes early onset obesity in a dominant-negative manner in humans through an unclear mechanism. Here, we report a pathologically important role of Sel1L-Hrd1, the protein complex of ER-associated degradation (ERAD), within POMC neurons. Mice with POMC neuron–specific Sel1L deficiency developed age-associated obesity due, at least in part, to the ER retention of POMC that led to hyperphagia. The Sel1L-Hrd1 complex targets a fraction of nascent POMC molecules for ubiquitination and proteasomal degradation, preventing accumulation of misfolded and aggregated POMC, thereby ensuring that another fraction of POMC can undergo normal posttranslational processing and trafficking for secretion. Moreover, we found that the disease-associated POMC-C28F mutant evades ERAD and becomes aggregated due to the presence of a highly reactive unpaired cysteine thiol at position 50. Thus, this study not only identifies ERAD as an important mechanism regulating POMC maturation within the ER, but also provides insights into the pathogenesis of monogenic obesity associated with defective prohormone folding. PMID:29457782

  9. Application of functional IDDQ testing in a VLIW processor towards detection of aging degradation

    NARCIS (Netherlands)

    Kerkhoff, Hans G.; Zhao, Yong

    2015-01-01

    In this paper, functional IDDQ testing has been applied for a 90nm VLIW processor to effectively detect aging degradation. This technique can provide health data for reliability evaluation as used in e.g. prognostic software for lifetime prediction. The test environment for validation, implementing

  10. Unit-based functional IDDT testing for aging degradation monitoring in a VLIW processor

    NARCIS (Netherlands)

    Zhao, Yong; Kerkhoff, Hans G.

    2015-01-01

    In this paper, functional unit-based IDDT testing has been applied for a 90nm VLIW processor to monitor its aging degradation. This technique can provide health data for reliability evaluation as used in e.g. prognostic software for lifetime prediction. The test-program development based on the

  11. Development of evaluation technique on ageing degradation of organic polymer in nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Yup; Nho, Young Chang; Jung, Sung Hee; Park, Eun Hee

    1999-03-01

    Radiation degradation of chlorosulfonated polyethylene (CSPE, Hypalon), crosslinked polyethylene (XLPE), poly (tetrafluoroethylene) (PTFE), poly (vinylidene fluoride) (PVDF), and ethylene rubber (EPR) of experimental formulation as cable insulating and sheathing materials were performed by accelerated ageing tests and was investigated by measuring the properties such as tensile strength, elongation, insulation resistance, melting temperature, oxygen index and thermal stimulated current. The status of radiation ageing test was reviewed and the requirement of qualification of nuclear equipment was documented.

  12. Development of evaluation technique on ageing degradation of organic polymer in nuclear power plant

    International Nuclear Information System (INIS)

    Kim, Ki Yup; Nho, Young Chang; Jung, Sung Hee; Park, Eun Hee

    1999-03-01

    Radiation degradation of chlorosulfonated polyethylene (CSPE, Hypalon), crosslinked polyethylene (XLPE), poly (tetrafluoroethylene) (PTFE), poly (vinylidene fluoride) (PVDF), and ethylene rubber (EPR) of experimental formulation as cable insulating and sheathing materials were performed by accelerated ageing tests and was investigated by measuring the properties such as tensile strength, elongation, insulation resistance, melting temperature, oxygen index and thermal stimulated current. The status of radiation ageing test was reviewed and the requirement of qualification of nuclear equipment was documented

  13. Assessing degradation of composite resin cements during artificial aging by Martens hardness.

    Science.gov (United States)

    Bürgin, Stefan; Rohr, Nadja; Fischer, Jens

    2017-05-19

    Aim of the study was to verify the efficiency of Martens hardness measurements in detecting the degradation of composite resin cements during artificial aging. Four cements were used: Variolink II (VL2), RelyX Unicem 2 Automix (RUN), PermaFlo DC (PDC), and DuoCem (DCM). Specimens for Martens hardness measurements were light-cured and stored in water at 37 °C for 1 day to allow complete polymerization (baseline). Subsequently the specimens were artificially aged by water storage at 37 °C or thermal cycling (n = 6). Hardness was measured at baseline as well as after 1, 4, 9 and 16 days of aging. Specimens for indirect tensile strength measurements were produced in a similar manner. Indirect tensile strength was measured at baseline and after 16 days of aging (n = 10). The results were statistically analyzed using one-way ANOVA (α = 0.05). After water storage for 16 days hardness was significantly reduced for VL2, RUN and DCM while hardness of PDC as well as indirect tensile strength of all cements were not significantly affected. Thermal cycling significantly reduced both, hardness and indirect tensile strength for all cements. No general correlation was found between Martens hardness and indirect tensile strength. However, when each material was analyzed separately, relative change of hardness and of indirect tensile strength revealed a strong linear correlation. Martens hardness is a sensible test method to assess aging of resin composite cements during thermal cycling that is easy to perform.

  14. Degradation study of different brands of paracetamol by UV spectroscopy

    Directory of Open Access Journals (Sweden)

    Safila Naveed

    2016-05-01

    Full Text Available Objective: To investgate the forced degradation study for the determination of degradation of the drug substance. Methods: Paracetamol was exposed to different conditions according to International Conference on Harmonization guideline. The amount of degradation product can be calculated with the help of UV spectrophotometer. The official test limits according to British Pharmacopoeia/United States Pharmacopoeia should not less than and should not more than lapelled amount. Forced degradation of drug substance was exposed to acidic and basic medium of panadol. Forced degradation of drug substance of panadol, disprol and calpol were also observed negligible difference in availability on exposure to UV and heat. This method can be used successfully for studying the stress degradation factors. Because this method is less time consuming and simple and cost effective also. Results: The brands i.e. calpol, panadol and disprol, when they come in contact with different degradation parameters (before, acid, base, heat and UV treatments according to statistical analysis, the result showed significant values (P < 0.05 which indicated that there was no degradation in any of the brand. Conclusions: The result indicated there is no degradation found in these brands.

  15. Degradation and Moisture Absorption Study of Potato-starch Linear ...

    African Journals Online (AJOL)

    Composite of linear low density polyethylene (LLDPE) and potato-starch was produced and subjected to degradation studies with the agencies of enzymes, exposure to weather and immersion in water. Enzymatic hydrolysis degraded the matrix to an extent greater than 40% loss in strength and about 20% loss in ...

  16. Ageing management studies of RAPS-1

    International Nuclear Information System (INIS)

    Bohra, A.K.; Jain, L.K.; Joshi, K.M.

    2006-01-01

    Unit-l of Rajasthan Atomic Power Station (RAPS-1) is the first nuclear power plant of India with pressurized heavy water reactor. The construction of Unit-l of Rajasthan Atomic Power Station (RAPS-1) was started in the year 1966 in collaboration with Canada. The Unit-1 achieved first criticality on August 1972 and was first synchronized to Grid on November 1972. During initial operation of the Unit, several problems were faced in its various systems and these were addressed by incorporating various engineering changes and procedures. In this unit various major innovative repairs were done like end shield leak repair, OPRD leak repair. Considering the operation of various systems of Unit-1, since year 1971 it was imperative to study ageing degradation mechanisms and mitigating measures were to be taken. Although the ageing management is a continuous process the opportunity of Unit-1 shutdown for upgradations from 30-04-2002 to 08-02-2004 was utilized for inspection and assessment of health of various SSC, which otherwise could not have been done with unit in operational state. This paper contains the following in detail. (1) Ageing management programme, its objectives and scope (2) Methodology of ageing management studies - Replacement and upgradation -Additional inspection programme based on ageing management review - Statistical analysis of ageing degradation occurrence - Estimation of residual life span of cables and relays (3) Criteria for selection of components for ageing management programme (4) Findings of ageing management studies-case studies. The ageing study done for RAPS-1 indicated that appropriate ageing monitoring methods and procedures exist in the station for taking timely mitigating measures. The technological obsoleteness has been overcome by installing new components of latest technology. On overall assessment, the Unit-1 was considered fit for further service. (author)

  17. Detection of thermal aging degradation and plastic strain damage for duplex stainless steel using SQUID sensor

    International Nuclear Information System (INIS)

    Otaka, M.; Evanson, S.; Hesegawa, K.; Takaku, K.

    1991-01-01

    An apparatus using a SQUID sensor is developed for nondestructive inspection. The measurements are obtained with the SQUID sensor located approximately 150 mm from the specimen. The degradation of thermal aging and plastic strain for duplex stainless steel is successfully detected independently from the magnetic characterization measurements. The magnetic flux density under high polarizing field is found to be independent of thermal aging. Coercive force increases with thermal aging time. On the other hand, the magnetic flux density under high field increases with the plastic strain. Coercive force is found to be independent of the plastic strain. (author)

  18. Assessment of degradation and aging of nuclear power plants concrete structures

    International Nuclear Information System (INIS)

    Busby, J.; Naus, D.; Graves, H.; Sheikh, A.; Le Pape, Y.; Rashid, J.; Saouma, V.; Wall, J.

    2015-01-01

    This paper summarizes the results of an expert-panel assessment of ageing degradation modes and mechanisms of concrete structures in NPPs, where, based on specific operating environments, degradation is likely to occur, or may have occurred; to define relevant aging and degradation modes and mechanisms; and to perform systematic assessment of the effects of these age-related degradation mechanisms on the future life of those materials and structures. The following 7 degradation modes and mechanisms have been identified as having the greatest potential impact on the ability of concrete structures to fulfill their safety related functions during long-term NPP operation. 1) Corrosion of conventional reinforcement is difficult to assess because of inaccessibility to inspection; 2) Creep of pre-stressed concrete containments continuously affects the internal stress state and adds to tendon relaxation and gradual loss of prestress; 3) Irradiation of concrete lacks sufficient data to for a clear evaluation of its effects on long-term operations; 4) Alkali-silica reaction potential consequences on the structural integrity of the containment; 5) Fracture/cracking, which is a well understood behavior characteristic of concrete structures and is accounted for in structural design, plays a unique role in post-tensioned containments during de-tensioning and re-tensioning operations which may be undertaken as part of life extension retrofit work, resulting in delamination, and may evolve with time as a creep-cracking interaction mechanism; 6) Boric acid attack of concrete in the spent fuel pool involves knowledge gaps related to the kinetics and the extent of the attack (role of the concrete mix design); 7) Corrosion of the inaccessible side of the spent fuel pool and containment liners and the stress corrosion cracking of the tendons are important degradation modes due to the absence of in-service inspection. The potential impact of these mechanisms may be mitigated by

  19. Organic chemical degradation by remote study of the redox conditions

    Science.gov (United States)

    Fernandez, P. M.; Revil, A.; Binley, A. M.; Bloem, E.; French, H. K.

    2014-12-01

    Monitoring the natural (and enhanced) degradation of organic contaminants is essential for managing groundwater quality in many parts of the world. Contaminated sites often have limited access, hence non-intrusive methods for studying redox processes, which drive the degradation of organic compounds, are required. One example is the degradation of de-icing chemicals (glycols and organic salts) released to the soil near airport runways during winter. This issue has been broadly studied at Oslo airport, Gardermoen, Norway using intrusive and non-intrusive methods. Here, we report on laboratory experiments that aim to study the potential of using a self-potential, DCresistivity, and time-domain induced polarization for geochemical characterization of the degradation of Propylene Glycol (PG). PG is completely miscible in water, does not adsorb to soil particles and does not contribute to the electrical conductivity of the soil water. When the contaminant is in the unsaturated zone near the water table, the oxygen is quickly consumed and the gas exchange with the surface is insufficient to ensure aerobic degradation, which is faster than anaerobic degradation. Since biodegradation of PG is highly oxygen demanding, anaerobic pockets can exist causing iron and manganese reduction. It is hypothesised that nitrate would boost the degradation rate under such conditions. In our experiment, we study PG degradation in a sand tank. We provide the system with an electron highway to bridge zones with different redox potential. This geo-battery system is characterized by self-potential, resistivity and induced polarization anomalies. An example of preliminary results with self-potential at two different times of the experiment can be seen in the illustration. These will be supplemented with more direct information on the redox chemistry: in-situ water sampling, pH, redox potential and electrical conductivity measurements. In parallel, a series of batch experiments have been

  20. Identification of component performance degradations caused by ageing using expert panels

    International Nuclear Information System (INIS)

    Nitoi, Mirela; Cristea, Dumitru; Pavelescu, Margarit

    2008-01-01

    Since the component ageing can be considered as one of the important causes of operating events reported, the identification of ageing effects and implementation of appropriate methods for mitigation of these effects represent an important preoccupation of many organizations and research activities. In the process of identification of ageing manifestation we can use either analysis of operational data or expert opinions, each of the methods having specific advantages and disadvantages. A reasonable combination of statistical, structural reliability and expert panel methods would be an appropriate approach in the failure probability assessments. In case when there are not enough operational data, the expert judgments represent the only viable alternative in the effort dedicated to identification of components and systems vulnerability to ageing. The panel use judgments to analyse the degradation produced by ageing, to score the components based on specific criteria and to rank them relative to one another. The paper presents the approach developed, including evaluation criteria and assigning indices for assessment of particular types of ageing degradation (the case of secondary system of TRIGA reactor). (authors)

  1. Studies on the physiology of microbial degradation of pentachlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Valo, R.; Apajalahti, J.; Salkinoja-Salonen, M.

    1985-03-01

    The requirements and conditions for pentachlorophenol (PCP) biodegradation by a mixed bacterial culture was studied. The effects of oxygen, nutrients, additional carbon sources, pH and temperature are described. Up to 90% of PCP was degraded into CO/sub 2/ and inorganic chloride in 1 week at an input concentration of <600 ..mu..M. Degradation continued when pO/sub 2/ was lowered to 0.0002 atm but ceased when pO/sub 2/ was further decreased to 0.00002 atm. Supplementary carbon sources, such as phenol, hydroxybenzoic acids or complex nutrients did not affect the biodegradation, but the presence of ammonium salts enhanced the rate of PCP degradation without affecting the yield of CO/sub 2/. The degrading organisms were shown to be procaryotic mesophiles; no degradation was shown at temperatures below +8/sup 0/ and above +50/sup 0/C. The optimum pH for degradation was from 6.4 to 7.2 and at higher pH value (8.4) degradation was inhibited more than at lower pH (5.6).

  2. Four new degradation products of doxorubicin: An application of forced degradation study and hyphenated chromatographic techniques

    Directory of Open Access Journals (Sweden)

    Dheeraj Kaushik

    2015-10-01

    Full Text Available Forced degradation study on doxorubicin (DOX was carried out under hydrolytic condition in acidic, alkaline and neutral media at varied temperatures, as well as under peroxide, thermal and photolytic conditions in accordance with International Conference on Harmonization (ICH guidelines Q1(R2. It was found extremely unstable to alkaline hydrolysis even at room temperature, unstable to acid hydrolysis at 80 °C, and to oxidation at room temperature. It degraded to four products (O-I–O-IV in oxidative condition, and to single product (A-I in acid hydrolytic condition. These products were resolved on a C8 (150 mm×4.6 mm, 5 µm column with isocratic elution using mobile phase consisting of HCOONH4 (10 mM, pH 2.5, acetonitrile and methanol (65:15:20, v/v/v. Liquid chromatography–photodiode array (LC–PDA technique was used to ascertain the purity of the products noted in LC–UV chromatogram. For their characterization, a six stage mass fragmentation (MS6 pattern of DOX was outlined through mass spectral studies in positive mode of electrospray ionization (+ESI as well as through accurate mass spectral data of DOX and the products generated through liquid chromatography–time of flight mass spectrometry (LC–MS–TOF on degraded drug solutions. Based on it, O-I–O-IV were characterized as 3-hydroxy-9-desacetyldoxorubicin-9-hydroperoxide, 1-hydroxy-9-desacetyldoxorubicin-9-hydroperoxide, 9-desacetyldoxorubicin-9-hydroperoxide and 9-desacetyldoxorubicin, respectively, whereas A-I was characterized as deglucosaminyl doxorubicin. While A-I was found to be a pharmacopoeial impurity, all oxidative products were found to be new degradation impurities. The mechanisms and pathways of degradation of doxorubicin were outlined and discussed. Keywords: Doxorubicin, TOF, Forced degradation, Liquid chromatography, Degradation product, Mass fragmentation pattern

  3. Ethylene propylene cable degradation during LOCA research tests: tensile properties at the completion of accelerated aging

    International Nuclear Information System (INIS)

    Bustard, L.D.

    1982-05-01

    Six ethylene-propylene rubber (EPR) insulation materials were aged at elevated temperature and radiation stress exposures common in cable LOCA qualification tests. Material samples were subjected to various simultaneous and sequential aging simulations in preparation for accident environmental exposures. Tensile properties subsequent to the aging exposure sequences are reported. The tensile properties of some, but not all, specimens were sensitive to the order of radiation and elevated temperature stress exposure. Other specimens showed more severe degradation when simultaneously exposed to radiation and elevated temperature as opposed to the sequential exposure to the same stresses. Results illustrate the difficulty in defining a single test procedure for nuclear safety-related qualification of EPR elastomers. A common worst-case sequential aging sequence could not be identified

  4. Prediction of the ageing of commercial lager beer during storage based on the degradation of iso-α-acids.

    Science.gov (United States)

    Blanco, Carlos A; Nimubona, Dieudonné; Caballero, Isabel

    2014-08-01

    Iso-α-acids and their chemically modified variants are responsible for the bitterness of beer and play a disproportionately large role in the final quality of beer. The current study was undertaken to predict the degradation of commercial lager beers related to changes in the concentration of trans-iso-α-acids during storage by using high-pressure liquid chromatography. In the analysed beers the concentration of isohumulone (average concentration 28 mg L(-1)) was greater than that of isocohumulone (20 mg L(-1)) and isoadhumulone (10 mg L(-1)). The kinetic parameters, activation energy and rate constant, of the trans-iso-α-acids were calculated. In the case of dark beers, the activation energy for the degradation of trans-isocohumulones was found to be higher than for trans-isohumulones and trans-isoadhumulones, whereas in pale and alcohol-free beers activation energies for the degradation of the three trans isomers were similar. The loss of iso-α-acids can be calculated using the activation energy of the degradation of trans-iso-α-acids and the temperature profile of the accelerated ageing. The results obtained in the investigation can be used in the beer industry to predict the alteration of the bitterness of beer during storage. © 2013 Society of Chemical Industry.

  5. Aspects of Degradability and Aging of Natural Rubber Latex Films Obtained by Induced Ionizing Radiation Processes of Latex Vulcanization

    International Nuclear Information System (INIS)

    Parra, D. F.

    2006-01-01

    This study refers to the degradability of NRLF, natural rubber latex films, obtained by ionizing radiation. Three types of NRLF were prepared: irradiated latex, irradiated latex with about 1% of soy lecithin and sulfur-vulcanized latex, by cold vulcanization process. The films were buried in vases of two different kinds of soil: common soil and common soil with earthworm humus. Fast aging tests in laboratory with exposition to ultraviolet rays were done in irradiated latex films and irradiated latex films with soy lecithin. The results obtained after ten months of tests with buried films agree with the results of the fast aging tests, showing singularities of each type of soil and each kind of latex process. It also shows how weather inclemency can induce the films degradation process. The sulfur-vulcanized films were weakly degraded when buried. The films with lecithin and buried in vase with only common soil showed the biggest mass loss, but the films with lecithin buried in vases with common earthworm humus and soil increased their weigh and dimensions due to fungi formation. The irradiated latex films are more degradable then the sulfur-vulcanized films. The irradiated latex film, unlike the sulfur vulcanized film, showed high fungi colonization when buried. We conclude that the irradiated latex films are more easily biodegradable than the sulfur vulcanized latex films. The biodegradability increases with the addition of small amounts of soy lecithin (∼1%). The mechanical resistance of the buried films decreased related to the non-buried ones, proving that the outdoor aging in soil and the presence of fungi in the films can modify the mechanical properties of the irradiated latex owing to the biodegradation

  6. Enhanced performance of aged rats in contingency degradation and instrumental extinction tasks.

    Science.gov (United States)

    Samson, Rachel D; Venkatesh, Anu; Patel, Dhara H; Lipa, Peter; Barnes, Carol A

    2014-04-01

    Normal aging in rats affects behavioral performance on a variety of associative learning tasks under Pavlovian conditions. There is little information, however, on whether aging also impacts performance of instrumental tasks. Young (9-12 months) and aged (24-27 months) Fisher 344 rats were trained to press distinct levers associated with either maltodextrin or sucrose. The rats in both age groups increased their lever press frequency at a similar rate, suggesting that the initial acquisition of this instrumental task is not affected by aging. Using a contingency degradation procedure, we then addressed whether aged rats could adapt their behavior to changes in action-outcome contingencies. We found that young and aged rats do adapt, but that a different schedule of reinforcement is necessary to optimize performance in each age group. Finally, we also addressed whether aged rats can extinguish a lever press action as well as young rats, using 2 40-min extinction sessions on consecutive days. While extinction profiles were similar in young and aged rats on the first day of training, aged rats were faster to extinguish their lever presses on the second day, in spite of their performance levels being similar at the beginning of the session. Together these data support the finding that acquisition of instrumental lever press behaviors is preserved in aged rats and suggest that they have a different threshold for switching strategies in response to changes in action-outcome associations. This pattern of result implies that age-related changes in the brain are heterogeneous and widespread across structures.

  7. Study of jojoba oil aging by FTIR.

    Science.gov (United States)

    Le Dréau, Y; Dupuy, N; Gaydou, V; Joachim, J; Kister, J

    2009-05-29

    As the jojoba oil was used in cosmetic, pharmaceutical, dietetic food, animal feeding, lubrication, polishing and bio-diesel fields, it was important to study its aging at high temperature by oxidative process. In this work a FT-MIR methodology was developed for monitoring accelerate oxidative degradation of jojoba oils. Principal component analysis (PCA) was used to differentiate various samples according to their origin and obtaining process, and to differentiate oxidative conditions applied on oils. Two spectroscopic indices were calculated to report simply the oxidation phenomenon. Results were confirmed and deepened by multivariate curve resolution-alternative least square method (MCR-ALS). It allowed identifying chemical species produced or degraded during the thermal treatment according to a SIMPLISMA pretreatment.

  8. Degradation Behavior of Lithium-Ion Batteries during Calendar Ageing – The Case of the Internal Resistance Increase

    DEFF Research Database (Denmark)

    Stroe, Daniel-Ioan; Swierczynski, Maciej Jozef; Kær, Søren Knudsen

    2018-01-01

    Lithium-ion batteries are regarded as the key energy storage technology for both e-mobility and stationary renewable energy storage applications. Nevertheless, the Lithium-ion batteries are complex energy storage devices, which are characterized by a complex degradation behavior, which affects both...... their capacity and internal resistance. This paper investigates, based on extended laboratory calendar ageing tests, the degradation of the internal resistance of a Lithium-ion battery. The dependence of the internal resistance increase on the temperature and state-of-charge level have been extensive studied...... and quantified. Based on the obtained laboratory results, an accurate semi-empirical lifetime model, which is able to predict with high accuracy the internal resistance increase of the Lithium-ion battery over a wide temperature range and for all state-of-charge levels was proposed and validated....

  9. Degradation of stainless castings. A literature study

    International Nuclear Information System (INIS)

    Norring, K.

    1995-10-01

    Duplex cast stainless steels, containing mainly austenite and some ferrite, is used for different components in light water reactors. These alloys have good mechanical properties, good weldability, and they are resistant to intergranular stress corrosion cracking (IGSCC). Examples of components where cast duplex stainless steel is used are pump housings, valves and pipe elbows. A model for the aging/embrittlement of these materials when used in light water reactors has been developed. The model is based on regression of a large data matrix. It is mainly the impact energy (Charpy V) that has been regarded. The model only requires knowledge of the chemical composition of the material but the prediction can be improved if additional data like initial impact properties and measured ferrite content are available. The model is also capable of predicting fracture toughness. The susceptibility to IGSCC in BWR environment is primarily determined by the amount of ferrite and the carbon content of the material. When the amount of ferrite exceeds 12%, IGSCC has not been observed regardless of the carbon content. At carbon contents lower than 0.035% in weld-sensitized material IGSCC was not observed regardless of the ferrite content. Data for corrosion fatigue in primary PWR and BWR environment are available. Under BWR conditions the crack propagation rate is decreased with decreasing corrosion potential, consequently also with decreasing oxygen content of the water. Some areas have been identified where additional work is needed. In all cases the efforts should focus on characterizing cast duplex stainless steel components removed from Swedish reactors. The characterization should include: Microstructure and chemical analysis, susceptibility to IGSCC, and a comparison with existing models for embrittlement. 24 refs, 12 figs

  10. Complex degradation processes lead to non-exponential decay patterns and age-dependent decay rates of messenger RNA.

    Directory of Open Access Journals (Sweden)

    Carlus Deneke

    Full Text Available Experimental studies on mRNA stability have established several, qualitatively distinct decay patterns for the amount of mRNA within the living cell. Furthermore, a variety of different and complex biochemical pathways for mRNA degradation have been identified. The central aim of this paper is to bring together both the experimental evidence about the decay patterns and the biochemical knowledge about the multi-step nature of mRNA degradation in a coherent mathematical theory. We first introduce a mathematical relationship between the mRNA decay pattern and the lifetime distribution of individual mRNA molecules. This relationship reveals that the mRNA decay patterns at steady state expression level must obey a general convexity condition, which applies to any degradation mechanism. Next, we develop a theory, formulated as a Markov chain model, that recapitulates some aspects of the multi-step nature of mRNA degradation. We apply our theory to experimental data for yeast and explicitly derive the lifetime distribution of the corresponding mRNAs. Thereby, we show how to extract single-molecule properties of an mRNA, such as the age-dependent decay rate and the residual lifetime. Finally, we analyze the decay patterns of the whole translatome of yeast cells and show that yeast mRNAs can be grouped into three broad classes that exhibit three distinct decay patterns. This paper provides both a method to accurately analyze non-exponential mRNA decay patterns and a tool to validate different models of degradation using decay data.

  11. Degradation of diclofenac by ultrasonic irradiation: kinetic studies and degradation pathways.

    Science.gov (United States)

    Nie, Er; Yang, Mo; Wang, Dong; Yang, Xiaoying; Luo, Xingzhang; Zheng, Zheng

    2014-10-01

    Diclofenac (DCF) is a widely used anti-inflammatory drug found in various water bodies, posing threats to human health. In this research, the effects of ultrasonic irradiation at 585kHz on the degradation of DCF were studied under the air, oxygen, argon, and nitrogen saturated conditions. First, the dechlorination efficiencies under the air, oxygen, argon, and nitrogen saturated conditions were calculated to be 67%, 60%, 53% and 59%. Second, there was full mineralization of nitrogen during DCF degradation under the air, oxygen, and argon saturated conditions, but no mineralization of nitrogen under the nitrogen-saturated condition. Different from nitrogen, only partial mineralization of carbon occurred under the four gas-saturated conditions. Third, OH scavengers were added to derive the rate constants in the three reaction zones: cavitation bubble, supercritical interface, and bulk solution. Comparison of the constants indicated that DCF degradation was not limited to the bulk solution as conventionally assumed. Oxidation in the supercritical interface played a dominant role under the air and oxygen saturated conditions, while OH reactions in the cavitation bubble and/or bulk solution were dominant under the nitrogen and argon saturated conditions. After the addition of H2O2, reactions in the cavitation bubble and bulk solution kept their dominant roles under the nitrogen and argon saturated conditions, while reaction in the supercritical interface decreased under the air and oxygen saturated conditions. Finally, LC-MS analysis was used to derive the by-products and propose the main pathways of DCF degradation by ultrasonic irradiation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. 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.

  13. Combined environment aging effects: radiation-thermal degradation of polyvinylchloride and polyethylene

    International Nuclear Information System (INIS)

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

    1981-01-01

    Results are presented for a case of polymer aging in which powerful synergisms are found between radiation and temperature. This effect was observed with formulations of polyvinylchloride and polyethylene and occurred in simultaneous and sequential radiation-thermal experiments. Dose rate dependencies, which appear to be mechanistically related to the synergism, were also found. The evidence indicates that these aging effects are mediated by a thermally induced breakdown of peroxides initially formed by the radiation. Similar effects could be important to material degradation in a variety of other types of combined-stress environment. A new technique, which uses PH 3 treatment of intact polymer specimens to test for the importance of peroxides in the pathway that leads to changes in macroscopic tensile properties, is described

  14. Aging studies for the CMS RPC system

    CERN Document Server

    Eysermans, Jan

    2017-01-01

    Aging effects are studied for the Resistive Plate Chambers (RPC) at the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Colider (LHC), which can manifest themselves during the High-Luminosity LHC (HL-LHC) running period. A dedicated consolidation program is set up using the CERN Gamma Irradiation Facility ++, where RPC detectors are exposed to a high gamma flux for a long term period equivalent to the HL-LHC operational time. Based on the past operational experience, the high background conditions are estimated and the RPC are tested under such circumstances. Several parameters are monitored as function of integrated charge and dedicated test beam periods allows measuring the detector efficiency as function of the background rate. In this work, an overview of the measurements which were performed for these studies is given. After having accumulated a significant amount of the total irradiation, no aging effects or degradation of the RPC detectors have been observed. These results suggest that ...

  15. Studies about behavior of microbial degradation of organic compounds

    International Nuclear Information System (INIS)

    Ohtsuka, Makiko

    2003-02-01

    Some of TRU waste include organic compounds, thus these organic compounds might be nutrients for microbial growth at disposal site. This disposal system might be exposed to high alkali condition by cement compounds as engineering barrier material. In the former experimental studies, it has been supposed that microbial exist under pH = 12 and the microbial activity acclimated to high alkali condition are able to degrade asphalt under anaerobic condition. Microbes are called extremophile that exist in cruel habitat as high alkali or reductive condition. We know less information about the activity of extremophile, though any recent studies reveal them. In this study, the first investigation is metabolic pathway as microbial activity, the second is microbial degradation of aromatic compounds in anaerobic condition, and the third is microbial activity under high alkali. Microbial metabolic pathway consist of two systems that fulfill their function each other. One system is to generate energy for microbial activities and the other is to convert substances for syntheses of organisms' structure materials. As these systems are based on redox reaction between substances, it is made chart of the microbial activity region using pH, Eh, and depth as parameter, There is much report that microbe is able to degrade aromatic compounds under aerobic or molecular O 2 utilizing condition. For degradation of aromatic compounds in anaerobic condition, supplying electron acceptor is required. Co-metabolism and microbial consortia has important role, too. Alcalophile has individual transporting system depending Na + and acidic compounds contained in cell wall. Generating energy is key for survival and growth under high alkali condition. Co-metabolism and microbial consortia are effective for microbial degradation of aromatic compounds under high alkali and reductive condition, and utilizable electron acceptor and degradable organic compounds are required for keeping microbial activity and

  16. Comparison of Quantifiler(®) Trio and InnoQuant™ human DNA quantification kits for detection of DNA degradation in developed and aged fingerprints.

    Science.gov (United States)

    Goecker, Zachary C; Swiontek, Stephen E; Lakhtakia, Akhlesh; Roy, Reena

    2016-06-01

    The development techniques employed to visualize fingerprints collected from crime scenes as well as post-development ageing may result in the degradation of the DNA present in low quantities in such evidence samples. Amplification of the DNA samples with short tandem repeat (STR) amplification kits may result in partial DNA profiles. A comparative study of two commercially available quantification kits, Quantifiler(®) Trio and InnoQuant™, was performed on latent fingerprint samples that were either (i) developed using one of three different techniques and then aged in ambient conditions or (ii) undeveloped and then aged in ambient conditions. The three fingerprint development techniques used were: cyanoacrylate fuming, dusting with black powder, and the columnar-thin-film (CTF) technique. In order to determine the differences between the expected quantities and actual quantities of DNA, manually degraded samples generated by controlled exposure of DNA standards to ultraviolet radiation were also analyzed. A total of 144 fingerprint and 42 manually degraded DNA samples were processed in this study. The results indicate that the InnoQuant™ kit is capable of producing higher degradation ratios compared to the Quantifiler(®) Trio kit. This was an expected result since the degradation ratio is a relative value specific for a kit based on the length and extent of amplification of the two amplicons that vary from one kit to the other. Additionally, samples with lower concentrations of DNA yielded non-linear relationships of degradation ratio with the duration of aging, whereas samples with higher concentrations of DNA yielded quasi-linear relationships. None of the three development techniques produced a noticeably different degradation pattern when compared to undeveloped fingerprints, and therefore do not impede downstream DNA analysis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Design Evolution Study - Aging Options

    International Nuclear Information System (INIS)

    McDaniel, P.

    2002-01-01

    The purpose of this study is to identify options and issues for aging commercial spent nuclear fuel received for disposal at the Yucca Mountain Mined Geologic Repository. Some early shipments of commercial spent nuclear fuel to the repository may be received with high-heat-output (younger) fuel assemblies that will need to be managed to meet thermal goals for emplacement. The capability to age as much as 40,000 metric tons of heavy metal of commercial spent nuclear he1 would provide more flexibility in the design to manage this younger fuel and to decouple waste receipt and waste emplacement. The following potential aging location options are evaluated: (1) Surface aging at four locations near the North Portal; (2) Subsurface aging in the permanent emplacement drifts; and (3) Subsurface aging in a new subsurface area. The following aging container options are evaluated: (1) Complete Waste Package; (2) Stainless Steel inner liner of the waste package; (3) Dual Purpose Canisters; (4) Multi-Purpose Canisters; and (5) New disposable canister for uncanistered commercial spent nuclear fuel. Each option is compared to a ''Base Case,'' which is the expected normal waste packaging process without aging. A Value Engineering approach is used to score each option against nine technical criteria and rank the options. Open issues with each of the options and suggested future actions are also presented. Costs for aging containers and aging locations are evaluated separately. Capital costs are developed for direct costs and distributable field costs. To the extent practical, unit costs are presented. Indirect costs, operating costs, and total system life cycle costs will be evaluated outside of this study. Three recommendations for aging commercial spent nuclear fuel--subsurface, surface, and combined surface and subsurface are presented for further review in the overall design re-evaluation effort. Options that were evaluated but not recommended are: subsurface aging in a new

  18. The Component Operational Experience Degradation and Ageing Program (CODAP). Review and lessons learned (2011-2014)

    International Nuclear Information System (INIS)

    Dragea, Tudor; Riznic, Jovica R.

    2015-01-01

    The structural integrity of piping systems is crucial to continuous and safe operation of nuclear power plants. Across all designs, the pressure boundary and its related piping and components, form one of the many levels of defense in the continuous and safe operation of a nuclear power plant. It is therefore necessary to identify, understand, evaluate and catalogue all of the various degradation mechanisms and failures that affect various piping systems and components across all nuclear power plants (NPP's). This need was first recognized in 1994 by the Swedish Nuclear Power Inspectorate (SKI) which launched a five-year Research and Development (R and D) project to explore the viability of creating an international pipe failure database (SKI-PIPE) (Riznic, 2007). The project was considered to be very successful and in 2002, the Organization for Economic Co-operation and Development (OECD) Pipe Failure Data Exchange (OPDE) was created. OPDE was operated under the umbrella of the OECD Nuclear Energy Agency (NEA) and was created in order to produce an international database on the piping service experience applicable to commercial nuclear power plants. After the successful completion of OPDE, the OECD, as well as other international members, agreed to participate in OPDE's successor: the Component Operational Experience Degradation and Ageing Program (CODAP). The objective of CODAP is to collect information on all possible events related to the failure and degradation of passive metallic components in NPP's. With CODAP winding down to the completion of its first phase in December 2014, this report will focus on the conclusions and the lessons learned throughout the many years of CODAP's implementation. There are currently 14 countries participating in CODAP, many of whom are industry leaders (France, Canada, U.S.A., Germany, Japan, Korea etc.). This cooperation on an international scale provides a library of OPerational EXperience (OPEX) for all participating NPP

  19. 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

  20. Assessment of the degradation efficiency of full-scale biogas plants: A comparative study of degradation indicators.

    Science.gov (United States)

    Li, Chao; Nges, Ivo Achu; Lu, Wenjing; Wang, Haoyu

    2017-11-01

    Increasing popularity and applications of the anaerobic digestion (AD) process has necessitated the development and identification of tools for obtaining reliable indicators of organic matter degradation rate and hence evaluate the process efficiency especially in full-scale, commercial biogas plants. In this study, four biogas plants (A1, A2, B and C) based on different feedstock, process configuration, scale and operational performance were selected and investigated. Results showed that the biochemical methane potential (BMP) based degradation rate could be use in incisively gauging process efficiency in lieu of the traditional degradation rate indicators. The BMP degradation rates ranged from 70 to 90% wherein plants A2 and C showed the highest throughput. This study, therefore, corroborates the feasibility of using the BMP degradation rate as a practical tool for evaluating process performance in full-scale biogas processes and spots light on the microbial diversity in full-scale biogas processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Monitoring the degradation of physical properties and fire hazards of high-impact polystyrene composite with different ageing time in natural environments.

    Science.gov (United States)

    Wang, Bibo; Zhang, Yan; Tao, Youji; Zhou, Xia; Song, Lei; Jie, Ganxin; Hu, Yuan

    2018-06-15

    The current study aims at monitoring the role of the different natural environments on the physical properties and fire hazards of HIPS composites ageing in Turpan and Qionghai. The results indicated that the chromatic aberration and degradation of surface appearance intensified with the increasing ageing time. More flame retardants migrated and were eroded for HIPS composites ageing in Qionghai than those ageing in Turpan, which was caused by the combination of sunlight, high temperature and rainwater in Qionghai. After degradation in the natural environments, the HIPS composites possessed the lower thermal stability and char residues, more toxic gases release, higher peak heat release rate and fire hazard. For example, the peak heat release rate in Qionghai increased by 88.9%, which is much higher than that of in Turpan (55.6%). Moreover, the tensile strength and elongation at break decreased by 46% and 59% for HIPS composites ageing in Turpan and reduced by 53% and 67% for HIPS composites aged in Qionghai, respectively. The results demonstrate that more serious degradation of physical properties and higher fire hazard for HIPS composites ageing in Qionghai than those in Turpan due to the different natural ageing environments. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Prediction of troponin-T degradation using color image texture features in 10d aged beef longissimus steaks.

    Science.gov (United States)

    Sun, X; Chen, K J; Berg, E P; Newman, D J; Schwartz, C A; Keller, W L; Maddock Carlin, K R

    2014-02-01

    The objective was to use digital color image texture features to predict troponin-T degradation in beef. Image texture features, including 88 gray level co-occurrence texture features, 81 two-dimension fast Fourier transformation texture features, and 48 Gabor wavelet filter texture features, were extracted from color images of beef strip steaks (longissimus dorsi, n = 102) aged for 10d obtained using a digital camera and additional lighting. Steaks were designated degraded or not-degraded based on troponin-T degradation determined on d 3 and d 10 postmortem by immunoblotting. Statistical analysis (STEPWISE regression model) and artificial neural network (support vector machine model, SVM) methods were designed to classify protein degradation. The d 3 and d 10 STEPWISE models were 94% and 86% accurate, respectively, while the d 3 and d 10 SVM models were 63% and 71%, respectively, in predicting protein degradation in aged meat. STEPWISE and SVM models based on image texture features show potential to predict troponin-T degradation in meat. © 2013.

  3. Physics Based Electrolytic Capacitor Degradation Models for Prognostic Studies under Thermal Overstress

    Science.gov (United States)

    Kulkarni, Chetan S.; Celaya, Jose R.; Goebel, Kai; Biswas, Gautam

    2012-01-01

    Electrolytic capacitors are used in several applications ranging from power supplies on safety critical avionics equipment to power drivers for electro-mechanical actuators. This makes them good candidates for prognostics and health management research. Prognostics provides a way to assess remaining useful life of components or systems based on their current state of health and their anticipated future use and operational conditions. Past experiences show that capacitors tend to degrade and fail faster under high electrical and thermal stress conditions that they are often subjected to during operations. In this work, we study the effects of accelerated aging due to thermal stress on different sets of capacitors under different conditions. Our focus is on deriving first principles degradation models for thermal stress conditions. Data collected from simultaneous experiments are used to validate the desired models. Our overall goal is to derive accurate models of capacitor degradation, and use them to predict performance changes in DC-DC converters.

  4. Degradation studies on plasticized PVC films submited to gamma radiation

    Directory of Open Access Journals (Sweden)

    Vinhas Glória Maria

    2003-01-01

    Full Text Available Poly (vinyl chloride, PVC, is a rigid polymer and for several of its applications must be compounded with plasticizing agents. The plasticizers minimize the dipolar interactions, which exist between the polymer's chains, promoting their mobility. In this work we studied the properties of PVC/plasticizer systems submitted to different doses of gamma radiation. We have used four commercial plasticizers amongt them di(2-ethylhexyl phthalate, DEHP, which is present in a great number of commercial applications. The PVC/plasticizer systems have been studied as films made by the solvent evaporation technique. Irradiated and non-irradiated films have been characterized by viscosimetric analysis, mechanical essays and infrared spectroscopy. The results have shown that the rigid, non plasticized, PVC film presented the greatest degradation index, while among the plasticized films the one which presented the larger degradation index due to chain scission was the DEHP plasticized PVC.

  5. Degradation studies on plasticised PVC films submitted to gamma radiation

    International Nuclear Information System (INIS)

    Vinhas, Gloria Maria; Souto-Maior, Rosa Maria; Lapa, Camila Maria; Almeida, Yeda Medeiros Bastos de

    2003-01-01

    Poly (vinyl chloride), PVC, is a rigid polymer and for several of its applications must be compounded with plasticizing agents. The plasticizers minimize the dipolar interactions, which exist between the polymer's chains, promoting their mobility. In this work we studied the properties of PVC/plasticizer systems submitted to different doses of gamma radiation. We have used four commercial plasticizers among them di(2-ethylhexyl) phthalate, DEHP, which is present in a great number of commercial applications. The PVC/plasticizer systems have been studied as films made by the solvent evaporation technique. Irradiated and non-irradiated films have been characterized by viscosimetric analysis, mechanical essays and infrared spectroscopy. The results have shown that the rigid, non plasticized, PVC film presented the greatest degradation index, while among the plasticised films the one which presented the larger degradation index due to chain scission was the DEHP plasticised PVC. (author)

  6. An initial examination of aging related degradation in turbine drives and governors for safety related pumps

    International Nuclear Information System (INIS)

    Cox, D.F.

    1991-01-01

    This study is being performed to examine the relationship between time dependent degradation, and current industry practices in the areas of maintenance, surveillance, and operation of steam turbine drives for safety related pumps. These pumps are located in the Auxiliary Feedwater (AFW) system for pressurized water reactor (PWR) plants, and the Reactor Core Isolation Cooling (RCIC) and High Pressure Coolant Injection (HPCI) systems for Boiling Water Reactor (BWR) facilities. This research has been conducted by examining current information in NPRDS, reviewing Licensee Event Reports, and thoroughly investigating contacts with operating plant personnel, and by personal observation. The reported information was reviewed to determine the cause of the event and the method of discovery. From this data attempts have been made at determining the predictability of events and possible preventive measures that may be implemented. Findings in a recent study on the Auxiliary Feedwater System (NUREG/CR-5404) indicate that the turbine drive is the single largest contributor to AFW system degradation. Recent improvements in maintenance practices and procedures, combined with a stabilization of the design seem to indicate that this equipment can be a reliable component in safety systems

  7. Study of Operating Parameters for Accelerated Anode Degradation in SOFCs

    DEFF Research Database (Denmark)

    Ploner, Alexandra; Hagen, Anke; Hauch, Anne

    2017-01-01

    Solid oxide fuel cell (SOFC) applications require lifetimes of several years on the system level. A big challenge is to demonstrate such exceptionally long lifetimes in ongoing R&D projects. Accelerated or compressed testing are alternative methods to obtain this. Activities in this area have been...... carried out without arriving at a generally accepted methodology. This is mainly due to the complexity of degradation mechanisms on the single SOFC components as function of operating parameters. In this study, we present a detailed analysis of approx. 180 durability tests regarding degradation of single...... SOFC components as function of operating conditions. Electrochemical impedance data were collected on the fresh and long-term tested SOFCs and used to de-convolute the individual losses of single SOFC cell components – electrolyte, cathode and anode. The main findings include a time-dependent effect...

  8. Photocatalytic degradation of rosuvastatin: Analytical studies and toxicity evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Tiele Caprioli, E-mail: tiele@enq.ufrgs.br [Chemical Engineering Department, Federal University of Rio Grande do Sul, Rua Engenheiro Luiz Englert s/n, CEP: 90040-040 Porto Alegre, RS (Brazil); Pizzolato, Tânia Mara [Chemical Institute, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Arenzon, Alexandre [Ecology Center, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Segalin, Jeferson [Biotechnology Center, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Lansarin, Marla Azário [Chemical Engineering Department, Federal University of Rio Grande do Sul, Rua Engenheiro Luiz Englert s/n, CEP: 90040-040 Porto Alegre, RS (Brazil)

    2015-01-01

    Photocatalytic degradation of rosuvastatin, which is a drug that has been used to reduce blood cholesterol levels, was studied in this work employing ZnO as catalyst. The experiments were carried out in a temperature-controlled batch reactor that was irradiated with UV light. Preliminary the effects of the photocatalyst loading, the initial pH and the initial rosuvastatin concentration were evaluated. The experimental results showed that rosuvastatin degradation is primarily a photocatalytic process, with pseudo-first order kinetics. The byproducts that were generated during the oxidative process were identified using nano-ultra performance liquid chromatography tandem mass spectrometry (nano-UPLC–MS/MS) and acute toxicity tests using Daphnia magna were done to evaluate the toxicity of the untreated rosuvastatin solution and the reactor effluent. - Highlights: • The photocatalytic degradation of rosuvastatin was studied under UV irradiation. • Commercial catalyst ZnO was used. • Initial rosuvastatin concentration, photocatalyst loading and pH were evaluated. • The byproducts generated during the oxidative process were detected and identified. • Acute toxicity tests using Daphnia magna were carried out.

  9. Consideration of time-evolving capacity distributions and improved degradation models for seismic fragility assessment of aging highway bridges

    International Nuclear Information System (INIS)

    Ghosh, Jayadipta; Sood, Piyush

    2016-01-01

    This paper presents a methodology to develop seismic fragility curves for deteriorating highway bridges by uniquely accounting for realistic pitting corrosion deterioration and time-dependent capacity distributions for reinforced concrete columns under chloride attacks. The proposed framework offers distinct improvements over state-of-the-art procedures for fragility assessment of degrading bridges which typically assume simplified uniform corrosion deterioration model and pristine limit state capacities. Depending on the time in service life and deterioration mechanism, this study finds that capacity limit states for deteriorating bridge columns follow either lognormal distribution or generalized extreme value distributions (particularly for pitting corrosion). Impact of column degradation mechanism on seismic response and fragility of bridge components and system is assessed using nonlinear time history analysis of three-dimensional finite element bridge models reflecting the uncertainties across structural modeling parameters, deterioration parameters and ground motion. Comparisons are drawn between the proposed methodology and traditional approaches to develop aging bridge fragility curves. Results indicate considerable underestimations of system level fragility across different damage states using the traditional approach compared to the proposed realistic pitting model for chloride induced corrosion. Time-dependent predictive functions are provided to interpolate logistic regression coefficients for continuous seismic reliability evaluation along the service life with reasonable accuracy. - Highlights: • Realistic modeling of chloride induced corrosion deterioration in the form of pitting. • Time-evolving capacity distribution for aging bridge columns under chloride attacks. • Time-dependent seismic fragility estimation of highway bridges at component and system level. • Mathematical functions for continuous tracking of seismic fragility along service

  10. Study on degradation of dimefuron in soil by nuclear technique

    International Nuclear Information System (INIS)

    Pakkong, P.; Vadeilai, J.

    1996-01-01

    Study on degradation of herbicide dimefuron in soil by using bio meter flask experiment was conducted under laboratory condition, 14 C-dimefuron was applied to three conditions of sterile soil normal and bio fertilizer added soil. Every month 14 CO 2 was collected from 1 N KOH in bio meter flask with in eight months period. Carbon-14 activity was analyzed by liquid scintillation counter. The result of dimefuron degradation as 14 CO 2 in sterile normal and bio fertilizer added soil were 0.96 percent 6.31 percent and 9.36 percent. It can be concluded that increasing in dimefuron degradation rate was involved by micro-organism activity. After eight month extracted and bounded residue of dimefuron in soil were analysed. Radioassay show that extracted and bounded residue were 58.62 and 29.58 percent in sterile soil 45.73 and 41.91 percent in normal soil 45.28 and 36.3 percent in bio fertilizer added soil

  11. Study of the thermal degradation of citrus seeds

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Montoya, V. [Centro de Quimica, Instituto de Ciencias, Universidad Autonoma de Puebla, Apdo. Postal J-55, Puebla 72570, Pue (Mexico); Instituto Nacional del Carbon, CSIC, Apartado 73, E-33080 Oviedo (Spain); Montes-Moran, M.A. [Instituto Nacional del Carbon, CSIC, Apartado 73, E-33080 Oviedo (Spain); Elizalde-Gonzalez, M.P. [Centro de Quimica, Instituto de Ciencias, Universidad Autonoma de Puebla, Apdo. Postal J-55, Puebla 72570, Pue (Mexico)

    2009-09-15

    The citrus seeds are one of the principal residues in the juice industry and their utilization can decrease significantly the problems of their final disposal. In this work the thermal degradation of three Mexican citrus seeds: orange (Citrus sinensis), lemon (Citrus Limon) and grapefruit (Citrus paradisi) was studied in nitrogen atmosphere. The two components (embryo and husk) of the seeds were characterized separately. The results showed that the thermal effects are very similar between the three embryos and the three husks. The embryos show higher degradability, superior content of nitrogen and higher heating value than the husks. The thermal degradation of the components of the three seeds is completed at 600 C and it is considered to be a global process derived from the decomposition of their principal components (cellulose, hemicellulose and lignin). The results suggest that mixing the three entire seeds will not lead to a severe deviation from their individual thermal behavior and that the industry could apply them for carbonization purposes. (author)

  12. Isolation and study of Biodegradiation Potential of Phenanthrene degrading bacteria

    Directory of Open Access Journals (Sweden)

    nafise Nourieh

    2009-11-01

    Full Text Available Polycyclic Aromatic Hydrocarbons (PAHs are among of potentially hazardous chemicals for environment and cause health concern. These compounds exhibit carcinogenic and/or mutagenic properties and are listed by the United States Environmental Protection Agency (USEPA as priority pollutants. Polycyclic Aromatic Hydrocarbons are hardly degraded and therefore bioremediation is often considered as a desirable and cost effective remediation technique for soil. contaminated with them. Materials and Methods: In this research Phenanthrene (C14H10, a three-benzene ring PAHs, was selected as a PAH representative compound and two different concentrations of Phenanthrene (100mg/kg and 500mg/kg were studied. First, PAH-degrading microorganisms were separated and after adaptation and enrichment PAH-degrading bacteria were identified. Results: The results showed that removal efficiency of Phenanthrene in the samples containing pseudomonas was more than other specified bacteria. Also the most removal efficiency of Phenanthrene occurred in first 45 days of biotreatment and then decreasing trend slowed down. Other finding was that the bioremediation of the lower concentration of Phenanthrene takes shorter time compared with the higher concentration and also the comparison of Phenanthrene bioremediation by pure bacteria and Consertium indicated that, at the beginning of the process, the pace of eliminating Phenanthrene by Consertium is more than other bacteria. Conclusion: Microbial analysis, based on cinfirmation tests and analytical profile index (api 20E kit tests, showed that Pseudomonas. SPP, Bacillus, Pseudomonas aeruginosa and Acinetobacter were the bacteria, responsible for Phenanthrene degradation. Extraction was conducted by ultra sonic method and Phenanthrene concentration was measured by (HPLC.

  13. Replacement of thermal column elastomeric gasket in pool type research reactors based on ageing and radiation degradation

    International Nuclear Information System (INIS)

    Garai, S.K.

    2006-01-01

    Pool type research reactors are designed with Thermal column facilities to irradiate samples at different flux levels of thermal neutrons. The sealing of demineralised pool water between stainless steel lined pool wall and the Aluminium Thermal column plate is achieved by an elastomeric gasket. The gasket joint is subjected to pool water temperature ranging from 25degC to 45degC and radiation field of the order of 104 -106 R/hr. The gasket loses its sealing properties due to ageing and radiation degradation after a few years, leading to the leakage and loss of the pool water. Though degradation of the gasket is, generally, predictable, some amount of uncertainty always remains in the leakage rate. The paper describes the study of a few elastomers in radiation environment and replacement of the Thermal column gasket of a swimming pool type research reactor. It includes the details of features like planning and scheduling, the actual sequential execution of the job, various problems encountered and corrective measures applied, engineering and radiological safety measures adopted, development of remote tools, disassembly and reassembly procedure and finally satisfactory completion of the site job in high radiation environment with minimum time and man rem consumption. (author)

  14. Aging related degradation in turbine drives and governors for safety related pumps

    International Nuclear Information System (INIS)

    Cox, D.F.

    1991-01-01

    This study is being performed to examine the relationship between time dependent degradation, and current industry practices in the areas of maintenance, surveillance, and operation of stem turbine drive for safety related pumps. These pumps are located in the Auxiliary Feedwater (AFW) system for pressurized water reactor (PWR) plants, and the Reactor Core Isolation Cooking (RCIC) and High Pressure Coolant Injection (HPCI) systems for Boiling Water Reactor (BWR) facilities. This research has been conducted by examining current information in the Nuclear Plant Reliability Data System (NPRDS), reviewing Licensee Event Reports, thoroughly investigating contacts with operating plant personnel, and by personal observation. This information was reviewed to determine the cause of each reported event and the method of discovery. From this data attempts have been made at determining the predictability of events and possible preventive measures that may be implemented

  15. THE FTIR STUDIES OF PHOTO-OXIDATIVE DEGRADATION OF POLYPROPYLENE

    Institute of Scientific and Technical Information of China (English)

    WEN Zaiqing; HU Xingzhou; SHEN Deyan

    1988-01-01

    The photo-oxidative degradation process of polypropylene film containing iron ions was investigated via FTIR and absorbance substraction technique. It is shown that the iron ions play an important role in the decomposition of hydroperoxide and the increase of the degradation rate of polypropylene film. Theamorphous region of PP film undergoes degradation prior to the crystalline one.

  16. Studies of action of heavy metals on caffeine degradation by ...

    African Journals Online (AJOL)

    Caffeine is an important naturally occurring compound that can be degraded by bacteria. Excessive caffeine consumption is known to have some adverse problems. Previously, Leifsonia sp. strain SIU capable of degrading caffeine was isolated from agricultural soil. The bacterium was tested for its ability to degrade caffeine ...

  17. Degradation of sucralose in groundwater and implications for age dating contaminated groundwater.

    Science.gov (United States)

    Robertson, W D; Van Stempvoort, D R; Spoelstra, J; Brown, S J; Schiff, S L

    2016-01-01

    The artificial sweetener sucralose has been in use in Canada and the US since about 2000 and in the EU since 2003, and is now ubiquitous in sanitary wastewater in many parts of the world. It persists during sewage treatment and in surface water environments and as such, has been suggested as a powerful tracer of wastewater. In this study, longer-term persistence of sucralose was examined in groundwater by undertaking a series of three sampling snapshots of a well constrained wastewater plume in Canada (Long Point septic system) over a 6-year period from 2008 to 2014. A shrinking sucralose plume in 2014, compared to earlier sampling, during this period when sucralose use was likely increasing, provides clear evidence of degradation. However, depletion of sucralose from a mean of 40 μg/L in the proximal plume zone, occurred at a relatively slow rate over a period of several months to several years. Furthermore, examination of septic tank effluent and impacted groundwater at six other sites in Canada, revealed that sucralose was present in all samples of septic tank effluent (6-98 μg/L, n = 32) and in all groundwater samples (0.7-77 μg/L, n = 64). Even though sucralose degradation is noted in the Long Point plume, its ubiquitous presence in the groundwater plumes at all seven sites implies a relatively slow rate of decay in many groundwater septic plume environments. Thus, sucralose has the potential to be used as an indicator of 'recent' wastewater contamination. The presence of sucralose identifies groundwater that was recharged after 2000 in Canada and the US and after 2003 in the EU and many Asian countries. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Radiogenic age and isotopic studies

    International Nuclear Information System (INIS)

    1991-01-01

    This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Reports in this issue give U-Pb zircon ages for rocks in Newfoundland, Yukon Territory, Manitoba, Ontario, and the Northwest Territories; present a compilation of K-Ar ages; and discuss Precambrian activity in New Brunswick, the geochronology of rock from the Northwest Territories, and reconnaissance Nd studies of rocks from the Northwest Territories. (figs., tabs., refs.)

  19. Study of distillation and degradation of perfluoro polyether

    International Nuclear Information System (INIS)

    Lopergolo, Lilian Cristine

    1997-01-01

    Perfluoro-polyethers, PFPE, were first synthesised by Sianesi and collaborators giving rise to a new lubricant oils and greases classes with several applications. Perfluoro polyethers have excellent properties, for instance: high chemical stability and thermal stability, high density, high radiation resistance and excellent lubricating properties. FOMBLIN-Y oil is one of the perfluoro polyethers used as a lubricant in vacuum systems applied in the UF 6 enrichment installations. Due to its excellent properties and for its applications in the nuclear field, IPEN-CNEN/S P had the interest to dominate its production technology with the aim to substitute the commercial FOMBLIN-Y oil used in the national consumption. The FOMBLIN-Y oil synthesis method, adopted in IPEN-CNEN/S P, made by the photooxidation of the hexa fluoro propylene. In this work we study the fraction separation of the national available production with restricted an increased molecular weights which was obtained by fraction distillation in a vacuum according to the ASTM D-1160 norm. We also study the catalytic effect of metals on the thermal stability of perfluoro polyethers. The inertness of perfluoro polyethers at temperatures higher than 300 deg C is strongly affected by presence of some metals. Al and Ti alloys cause fluid degradation at 250 deg C. This degradation is very important because it has a yield increase of the perfluoro polyethers production. (author)

  20. Perceived age as clinically useful biomarker of ageing: cohort study

    DEFF Research Database (Denmark)

    Christensen, Kaare; Thinggaard, Mikael; McGue, Matt

    2009-01-01

    OBJECTIVE: To determine whether perceived age correlates with survival and important age related phenotypes. DESIGN: Follow-up study, with survival of twins determined up to January 2008, by which time 675 (37%) had died. SETTING: Population based twin cohort in Denmark. PARTICIPANTS: 20 nurses, 10...... young men, and 11 older women (assessors); 1826 twins aged >or=70. MAIN OUTCOME MEASURES: Assessors: perceived age of twins from photographs. Twins: physical and cognitive tests and molecular biomarker of ageing (leucocyte telomere length). RESULTS: For all three groups of assessors, perceived age...... increased with increasing discordance in perceived age within the twin pair-that is, the bigger the difference in perceived age within the pair, the more likely that the older looking twin died first. Twin analyses suggested that common genetic factors influence both perceived age and survival. Perceived...

  1. Peculiar Features of Thermal Aging and Degradation of Rapidly Quenched Stainless Steels under High-Temperature Exposures

    Science.gov (United States)

    Shulga, A. V.

    2017-12-01

    This article presents the results of comparative studies of mechanical properties and microstructure of nuclear fuel tubes and semifinished stainless steel items fabricated by consolidation of rapidly quenched powders and by conventional technology after high-temperature exposures at 600 and 700°C. Tensile tests of nuclear fuel tube ring specimens of stainless austenitic steel of grade AISI 316 and ferritic-martensitic steel are performed at room temperature. The microstructure and distribution of carbon and boron are analyzed by metallography and autoradiography in nuclear fuel tubes and semifinished items. Rapidly quenched powders of the considered steels are obtained by the plasma rotating electrode process. Positive influence of consolidation of rapidly quenched powders on mechanical properties after high-temperature aging is confirmed. The correlation between homogeneous distribution of carbon and boron and mechanical properties of the considered steel is determined. The effects of thermal aging and degradation of the considered steels are determined at 600°C and 700°C, respectively.

  2. Study on the Degradation of Polylactide Microsphere In Vitro

    Institute of Scientific and Technical Information of China (English)

    HeYing; WeiShuli

    2001-01-01

    This report concentrated on the rules and mechanism of the degradation of polylactide and the microspheres. The rate of degradation was assessed with five methods: observation of microsphere surface morphology by SEM, determination of the weight loss of the microspheres, determination of the molecular mass of the polymers by GPC, determination of pH and determination of the contents of lactic acid by UV spectrophotometry. The degradation of polylactide microspheres showed two-phase characteristics. At the early stage of the degradation, the high molecular mass polymers were cleaved into lower molecular mass fractions and at the late stage, there was a period of erosion and weight loss of the microspheres. The degradation was much slower for polymers with a higher molecular mass. The polylactide degradation showed good regularity.

  3. Detection of Degradation Effects in Field-Aged c-Si Solar Cells through IR Thermography and Digital Image Processing

    Directory of Open Access Journals (Sweden)

    E. Kaplani

    2012-01-01

    Full Text Available Due to the vast expansion of photovoltaic (PV module production nowadays, a great interest is shown in factors affecting PV performance and efficiency under real conditions. Particular attention is being given to degradation effects of PV cells and modules, which during the last decade are seen to be responsible for significant power losses observed in PV systems. This paper presents and analyses degradation effects observed in severely EVA discoloured PV cells from field-aged modules operating already for 18–22 years. Temperature degradation effects are identified through IR thermography in bus bars, contact solder bonds, blisters, hot spots, and hot areas. I-V curve analysis results showed an agreement between the source of electrical performance degradation and the degradation effects in the defected cell identified by the IR thermography. Finally, an algorithm was developed to automatically detect EVA discoloration in PV cells through processing of the digital image alone in a way closely imitating human perception of color. This nondestructive and noncostly solution could be applied in the detection of EVA discoloration in existing PV installations and the automatic monitoring and remote inspection of PV systems.

  4. Solvent degradation and cleanup: a survey and recent ORNL studies

    International Nuclear Information System (INIS)

    Mailen, J.C.; Tallent, O.K.

    1984-01-01

    This paper surveys the mechanisms for degradation of the tributyl phosphate and diluent components of Purex solvent by acid and radiation, reviews the problems encountered in plant operations resulting from the presence of these degradation products, and discusses methods for minimizing the formation of degradation products and accomplishing their removal. Scrubbing solutions containing sodium carbonate or hydroxylamine salts and secondary cleanup of solvents using solid sorbents are evaluated. Finally, recommendations for improved solvent cleanup are presented. 50 references, 4 figures, 3 tables

  5. Poly-Ub-substrate-degradative activity of 26S proteasome is not impaired in the aging rat brain.

    Directory of Open Access Journals (Sweden)

    Carolin Giannini

    Full Text Available Proteostasis is critical for the maintenance of life. In neuronal cells an imbalance between protein synthesis and degradation is thought to be involved in the pathogenesis of neurodegenerative diseases during aging. Partly, this seems to be due to a decrease in the activity of the ubiquitin-proteasome system, wherein the 20S/26S proteasome complexes catalyse the proteolytic step. We have characterised 20S and 26S proteasomes from cerebrum, cerebellum and hippocampus of 3 weeks old (young and 24 month old (aged rats. Our data reveal that the absolute amount of the proteasome is not dfferent between both age groups. Within the majority of standard proteasomes in brain the minute amounts of immuno-subunits are slightly increased in aged rat brain. While this goes along with a decrease in the activities of 20S and 26S proteasomes to hydrolyse synthetic fluorogenic tripeptide substrates from young to aged rats, the capacity of 26S proteasomes for degradation of poly-Ub-model substrates and its activation by poly-Ub-substrates is not impaired or even slightly increased in brain of aged rats. We conclude that these alterations in proteasome properties are important for maintaining proteostasis in the brain during an uncomplicated aging process.

  6. Degradation of Bilayer Organic Light-Emitting Diodes Studied by Impedance Spectroscopy.

    Science.gov (United States)

    Sato, Shuri; Takata, Masashi; Takada, Makoto; Naito, Hiroyoshi

    2016-04-01

    The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3 layer.

  7. Age determination and geological studies

    International Nuclear Information System (INIS)

    Stevens, R.D.; Delabio, R.N.; Lachance, G.R.

    1982-01-01

    Two hundred and eight potassium-argon age determinations carried out on Canadian rocks and minerals are reported. Each age determination is accompanied by a description of the rock and mineral concentrate used; brief interpretative comments regarding the geological significance of each age are also provided where possible. The experimental procedures employed are described in brief outline and the constants used in the calculation of ages are listed. Two geological time-scales are reproduced in tabular form for ready reference and an index of all Geological Survey of Canada K-Ar age determinations published in this format has been prepared using NTS quadrangles as the primary reference

  8. Biological degradation of EDTA in pulping effluents at higher pH - a laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Ek, M; Remberger, M; Allard, A S

    1999-01-01

    The biological degradation of EDTA at different pH, sludge load and sludge age has been investigated in laboratory experiments. The experiments showed that relatively fast degradation of EDTA in the form found in this waste water (from production of TMP) took place at least at pH around 8.5 with moderate COD load and high sludge age. In continuous reactors the degradation of EDTA in a pulp and paper waste water was 2-3 mg EDTA/g SS*day at both pH 7 and 8,5, and at sludge ages from 5 to 21 days. The degradation was dependent on sludge load, and no degradation was seen above 1 g COD/g SS*day. In kinetic experiments with half strength waste water the same degradation rate (1,5-2 mg EDTA/g SS*day) was found at pH 7 and at pH 8,5 with sludge of low age (9 and 5 days SRT). Much faster degradation was found at pH 8,5 with sludge of high age (21 days in the continuous experiment). The mean degradation rate was over 10 mg EDTA/g SS*day from 20 to 5 mg EDTA/l. v{sub max} was determined to be 35 mg EDTA/g SS*day and K{sub M} to 31 mg EDTA/l. COD removal was at least as good at pH 8,5 as at pH 7. Sludge properties were best at pH 8,5 and long sludge retention time (giving low sludge load). Both sludge volume index and residual suspended solids after sedimentation were lower than under normal conditions at pH 7. The direct cost for caustic lime would be about 15 SEK per ton of TMP, with a water like the one investigated here. This can vary a lot depending on starting pH and buffering capacity. Costs for addition of nitrogen source could probably be omitted, but this is normally not more than 1-2 SEK per ton of TMP. The extra need for oxygen in the treatment would not be more than some percent, but may be important if oxygen is limited. A substantial extra cost would be if the aeration volume has to be increased. According to the best results from the kinetic study, this would not be needed in an extended aeration activated plant with 2 days HRT and sludge concentrations of 2

  9. Study of polypropylene irradiation to ensure the control of its environmental degradation

    International Nuclear Information System (INIS)

    Romano, Rebeca da Silva Grecco

    2017-01-01

    UV light, heat, and pollutants can interact with Polypropylene (PP) molecules, mainly with the tertiary carbon producing free radicals which can react with oxygen producing changes in its properties. PP has outstanding chemical and physical properties and a good processability at very low market price. In addition, PP is extensively used for manufacturing various kinds of products, however due to its large-scale consumption a lot of waste is generated at the end of their life cycle to the environment with low rate degradation. Controlled degradation of PP can be achieved by exposing the polymers to well defined parameters, such as absorbed dose, intemperies, oxygen, etc. In this study, structural changes in PP macro-molecule are created upon exposure to ionizing radiation such as: main chain scission, crosslinking and peroxidation (in presence of air). This study has the objective of comparing the environmental and accelerated exposures of PP neat, PP irradiated with 12,5 kGy and 20 kGy and the incorporation of the commercial pro-degradant d2w®. Dumbbell samples were manufactured by injection molding and exposed to the environment during 180 days and to accelerated aging to 192 days. The samples were characterized by Mechanical Testing, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (DRX) and Differential Scanning Calorimetry (DSC). The samples previously irradiated, PP 20 kGy, after environmental aging showed higher oxidation and presence of surface cracks than the PP d2w® and PP neat. They also showed presence of carbonyl groups, decreases in elongation at break, increase in Strength Modulus and decrease of melting temperature corroborating with degradation. (author)

  10. Evaluation of Degradation of Isothermally Aged Plasma-Sprayed Thermal Barrier Coating

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Jae Mean; Seok, Chang Sung; Kang, Min Sung; Kim, Dae Jin [Sungkyunkwan University, Seoul (Korea, Republic of); Lee, Dong Hoon [HYUNDAI STEEL CO., Incheon (Korea, Republic of); Kim, Mun Young [KPS Gas Turbine Technology Service Center, Seongnam (Korea, Republic of)

    2010-04-15

    The thermal barrier coating of a gas turbine blade was degraded by isothermal heating in a furnace and by varying the exposure time and temperature. Then, a micro-Vickers hardness test was conducted on the cross section of the bond coat and Ni-based superalloy substrate. Further, the thickness of TGO(Thermally Grown Oxide) was measured by using an image analyzer, and the changes in the microstructure and element contents in the coating were analyzed by using an optical microscope and by performing SEM-EDX analysis. No significant change was observed in the Vickers hardness of the bond coat when the coated specimen was degraded at a high temperature: delamination was observed between the top coat and the bond coat when the coating was degraded for 50 h at a temperature 1,151 .deg. C.

  11. Radiogenic age and isotopic studies

    International Nuclear Information System (INIS)

    1992-01-01

    This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Report 5 contains 24 papers from most regions of Canada, but particularly from British Columbia. The Geochronology Laboratory has, over the years, provided substantial U-Pb dating for the Cordilleran Division of the Geological Survey of Canada in Vancouver, and the results of a number of these studies are presented this year. A compilation of K-Ar ages is given. (figs., tabs., refs.)

  12. 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.

  13. Mechanistic studies of the alkaline degradation of cellulose in cement

    International Nuclear Information System (INIS)

    Greenfield, B.F.; Robertson, G.P.; Spindler, M.W.; Harrison, W.N.; Somers, P.J.

    1993-07-01

    The alkaline degradation of cellulose-based materials under conditions simulating those of a deep underground radioactive waste repository has been investigated. A number of key degradation products, of which 2-C-(hydroxymethyl)-3-deoxy-D-pentonic acid (isosaccharinic acid) is the most important, have been synthesised, and the solubilities of their plutonium complexes have been determined. Analysis of leachates of anaerobically degraded cellulose has shown concentrations of organic acids which are broadly consistent with the enhanced plutonium solubilities found in these leachates. Reaction mechanisms have been identified that can lead to isosaccharinic acid production by non-oxidative transformations, which may be catalysed by some divalent cations. (Author)

  14. Extensions and applications of degradation modeling

    International Nuclear Information System (INIS)

    Hsu, F.; Subudhi, M.; Samanta, P.K.; Vesely, W.E.

    1991-01-01

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, the authors discuss some of the extensions and applications of degradation modeling. The extensions and applications of the degradation modeling approaches discussed are: (a) theoretical developments to study reliability effects of different maintenance strategies and policies, (b) relating aging-failure rate to degradation rate, and (c) application to a continuously operating component

  15. AGE RELATED DEGRADATION OF STEAM GENERATOR INTERNALS BASED ON INDUSTRY RESPONSES TO GENERIC LETTER 97-06

    International Nuclear Information System (INIS)

    SUBUDHI, M.; SULLIVAN, JR. E.J.

    2002-01-01

    THIS PAPER PRESENTS THE RESULTS OF AN AGING ASSESSMENT OF THE NUCLEAR POWER INDUSTRY RESPONSES TO NRC GENERIC LETTER 97-06 ON THE DEGRADATION OF STEAM GENERATOR INTERNALS EXPERIENCED AT ELECTRICITE DE FRANCE (EDF) PLANTS IN FRANCE AND AT A UNITED STATES PRESSURIZED WATER REACTOR (PWR). WESTINGHOUSE (W), COMBUSTION ENGINEERING (CE), AND BABCOCK AND WILCOX (BW) STEAM GENERATOR MODELS, CURRENTLY IN SERVICE AT U.S. NUCLEAR POWER PLANTS, POTENTIALLY COULD EXPERIENCE DEGRADATION SIMILAR TO THATFOUND AT EDF PLANTS AND THE U.S. PLANT. THE STEAM GENERATORS IN MANY OF THE U.S. PWRS HAVE BEEN REPLACED WITH STEAM GENERATORS WITH STEAM GENERATORS WITH IMPROVED DESIGNS AND MATERIALS. THESE REPLACEMENT STEAM GENERATORS HAVE BEEN MANUFACTURED IN THE U.S. AND ABROAD. DURING THIS ASSESSMENT, EACH OF THE THREE OWNERS GROUPS (W,CE, AND BW) IDENTIFIED FOR ITS STEAM GENERATOR, MODELS ALL THE POTENTIAL INTERNAL COMPONENTS THAT ARE VULNERABLE TO DEGRADATION WHILE IN SERVICE. EACH OWNERS GROUPDEVELOPED INSPEC TION AND MONITORING GUIDANCE AND RECOMMENDATIONS FOR ITS PARTICULAR STEAM GENERATOR MODELS. THE NUCLEAR ENERGY INSTITUTE INCORPORATED IN NEI 97-06 STEAM GENERATOR PROGRAM GUIDELINES, A REQUIREMENT TO MONITOR SECONDARY SIDE STEAM GENERATOR COMPONENTS IF THEIR FAILURE COULD PREVENT THE STEAM GENERATOR FROM FULFILLING ITS INTENDED SAFETY-RELATED FUNCTION. LICENSEES INDICATED THAT THEY IMPLEMENTED OR PLANNED TO IMPLEMENT, AS APPROPRIATE FOR THEIR STEAM GENERATORS, THEIR OWNERS GROUPRECOMMENDATIONS TO ADDRESS THE LONG-TERM EFFECTS OF THE POTENTIAL DEGRADATION MECHANISMS ASSOCIATED WITH THE STEAM GENERATOR INTERNALS

  16. Framework for Structural Online Health Monitoring of Aging and Degradation of Secondary Systems due to some Aspects of Erosion

    Energy Technology Data Exchange (ETDEWEB)

    Gribok, Andrei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Patnaik, Sobhan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Williams, Christian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pattanaik, Marut [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kanakala, Raghunath [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    This report describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants. The report also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real-time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at answering this challenge by combining long-range guided wave technologies with other monitoring techniques, which can significantly increase the inspection length and pinpoint the locations that degraded the most. More widely, the report suggests research efforts aimed at developing, validating, and deploying online corrosion monitoring techniques for complex geometries, which are pervasive in NPPs.

  17. Framework for Structural Online Health Monitoring of Aging and Degradation of Secondary Systems due to some Aspects of Erosion

    International Nuclear Information System (INIS)

    Gribok, Andrei; Patnaik, Sobhan; Williams, Christian; Pattanaik, Marut; Kanakala, Raghunath

    2016-01-01

    This report describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants. The report also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real-time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at answering this challenge by combining long-range guided wave technologies with other monitoring techniques, which can significantly increase the inspection length and pinpoint the locations that degraded the most. More widely, the report suggests research efforts aimed at developing, validating, and deploying online corrosion monitoring techniques for complex geometries, which are pervasive in NPPs.

  18. Radiogenic age and isotopic studies

    International Nuclear Information System (INIS)

    Parrish, R.R.

    1990-01-01

    This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Reports in this issue cover methods for Rb-Sr and Sm-Nd isotopic analyses; 40 Ar- 39 Ar ages for the New Quebec Crater and for basaltic rocks; U-Pb ages for a differentiated mafic sill in the Ogilvie Mountains, plutonic rocks in the Contwoyto-Nose Lakes are, zircons from the Anton Complex, the Clinton-Colden gabbro-anorthosite intrusion, the Himag plutonic suite, the Campbell granite, the Central Gneiss Belt, Silurian granites, a metarhyolite, plagiogranite and gabbro, and the Wage shear zone; Rb-Sr ages for granitic rocks; K-Ar and Rb-Sr geochronology of granites; a compilation of K-Ar ages; ages of archean and proterozoic mylonites and pre-Misi granitoid domes; and reconnaissance geochronology of Baffin Island

  19. Aqueous photodegradation of antibiotic florfenicol: kinetics and degradation pathway studies.

    Science.gov (United States)

    Zhang, Ya; Li, Jianhua; Zhou, Lei; Wang, Guoqing; Feng, Yanhong; Wang, Zunyao; Yang, Xi

    2016-04-01

    The occurrence of antibacterial agents in natural environment was of scientific concern in recent years. As endocrine disrupting chemicals, they had potential risk on ecology system and human beings. In the present study, the photodegradation kinetics and pathways of florfenicol were investigated under solar and xenon lamp irradiation in aquatic systems. Direct photolysis half-lives of florfenicol were determined as 187.29 h under solar irradiation and 22.43 h under xenon lamp irradiation, respectively. Reactive oxygen species (ROS), such as hydroxyl radical (·OH) and singlet oxygen ((1)O2) were found to play an important role in indirect photolysis process. The presence of nitrate and dissolved organic matters (DOMs) could affect photolysis of florfenicol in solutions through light screening effect, quenching effect, and photoinduced oxidization process. Photoproducts of florfenicol in DOMs solutions were identified by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) analysis techniques, and degradation pathways were proposed, including photoinduced hydrolysis, oxidation by (1)O2 and ·OH, dechlorination, and cleavage of the side chain.

  20. Degradation of metallic materials studied by correlative tomography

    Science.gov (United States)

    Burnett, T. L.; Holroyd, N. J. H.; Lewandowski, J. J.; Ogurreck, M.; Rau, C.; Kelley, R.; Pickering, E. J.; Daly, M.; Sherry, A. H.; Pawar, S.; Slater, T. J. A.; Withers, P. J.

    2017-07-01

    There are a huge array of characterization techniques available today and increasingly powerful computing resources allowing for the effective analysis and modelling of large datasets. However, each experimental and modelling tool only spans limited time and length scales. Correlative tomography can be thought of as the extension of correlative microscopy into three dimensions connecting different techniques, each providing different types of information, or covering different time or length scales. Here the focus is on the linking of time lapse X-ray computed tomography (CT) and serial section electron tomography using the focussed ion beam (FIB)-scanning electron microscope to study the degradation of metals. Correlative tomography can provide new levels of detail by delivering a multiscale 3D picture of key regions of interest. Specifically, the Xe+ Plasma FIB is used as an enabling tool for large-volume high-resolution serial sectioning of materials, and also as a tool for preparation of microscale test samples and samples for nanoscale X-ray CT imaging. The exemplars presented illustrate general aspects relating to correlative workflows, as well as to the time-lapse characterisation of metal microstructures during various failure mechanisms, including ductile fracture of steel and the corrosion of aluminium and magnesium alloys. Correlative tomography is already providing significant insights into materials behaviour, linking together information from different instruments across different scales. Multiscale and multifaceted work flows will become increasingly routine, providing a feed into multiscale materials models as well as illuminating other areas, particularly where hierarchical structures are of interest.

  1. Modelling of degradation processes in creep resistant steels through accelerated creep tests after long-term isothermal ageing

    Energy Technology Data Exchange (ETDEWEB)

    Sklenicka, V.; Kucharova, K.; Svoboda, M.; Kroupa, A.; Kloc, L. [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials; Cmakal, J. [UJP PRAHA a.s., Praha-Zbraslav (Czech Republic)

    2010-07-01

    Creep behaviour and degradation of creep properties of creep resistant materials are phenomena of major practical relevance, often limiting the lives of components and structures designed to operate for long periods under stress at elevated and/or high temperatures. Since life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for the projected designed life, methods of creep properties assessment based on microstructural evolution in the material during creep rather than simple parametric extrapolation of short-term creep tests are necessary. In this paper we will try to further clarify the creep-strength degradation of selected advanced creep resistant steels. In order to accelerate some microstructural changes and thus to simulate degradation processes in long-term service, isothermal ageing at 650 C for 10 000 h was applied to P91 and P23 steels in their as-received states. The accelerated tensile creep tests were performed at temperature 600 C in argon atmosphere on all steels both in the as-received state and after long-term isothermal ageing, in an effort to obtain a more complete description of the role of microstructural stability in high temperature creep of these steels. Creep tests were followed by microstructural investigations by means of both transmission and scanning electron microscopy and by the thermodynamic calculations. The applicability of the accelerated creep tests was verified by the theoretical modelling of the phase equilibria at different temperatures. It is suggested that under restructed oxidation due to argon atmosphere microstructural instability is the main detrimental process in the long-term degradation of the creep rupture strength of these steels. (orig.)

  2. Resistance temperature sensor aging degradation identification using LCSR (Loop Current Step Response) test

    International Nuclear Information System (INIS)

    Santos, Roberto Carlos dos; Goncalves, Iraci Martine Pereira

    2013-01-01

    response time of the sensor to changes in external temperature is identified by means of the LCSR transformation. Since the response time is controlled by heat diffusion, response time could degrade either because of changes in the overall heat-transfer resistance and/or effective heat capacity of the sensor material. Response time generally degrades due to the following possible causes: changes in the properties of the filler or bonding material, material on sensor surface, and changes in contact pressure or contact area. Therefore, the LCSR test results can either give information about the time constant value and the level of RTD response-time degradation. In order to identify the time response degradation causes, LCSR laboratory tests were performed using normal and artificially degraded RTDs. This work presents the results of time response time degradation identification obtained from LCSR test. (author)

  3. 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)

  4. Influencing factors and kinetic studies of imidacloprid degradation by ozonation.

    Science.gov (United States)

    Chen, Shi; Deng, Jing; Deng, Yang; Gao, Naiyun

    2018-03-02

    Batch kinetic tests in ozonation of imidacloprid from water were performed in this study. The pseudo-first-order rate constant of imidacloprid degradation was increased from 0.079 to 0.326 min -1 with the increasing pH from 6.02 to 8.64 at an average ozone dose of 1.149 mg L -1 . When the alkalinity was increased from 0 to 250 mg L -1 NaHCO 3 , the pseudo-first-order rate constants decreased from 0.121 to 0.034 min -1 . These results suggested that the predominant oxidant gradually switched from ozone to hydroxyl radicals ([Formula: see text]) with the increase in solution pH. The secondary rate constant [Formula: see text] (10.92 ± 0.12 M -1 s -1 ) for the reaction of imidacloprid and molecular ozone was determined at pH 2.0 and in the presence of 50 mM ter-butyl alcohol (p-chlorobenzoic acid, pCBA), respectively. An indirect competition method was used to determine the secondary rate constant for [Formula: see text] oxidation of imidacloprid in the presence of pCBA as the reference compound. The rate constants [Formula: see text] were estimated to range 2.65-3.79 M -1 s -1 at pH 6.02-8.64. Results obtained from this study demonstrate that ozonation appears to be an effective method to remove imidacloprid from water.

  5. Degradation of impact fracture during accelerated aging of weld metal on microalloyed steel

    International Nuclear Information System (INIS)

    Vargas-Arista, B.; Hallen, J. M.; Albiter, A.; Angeles-Chavez, C.

    2008-01-01

    The effect of accelerated aging on the toughness and fracture of the longitudinal weld metal on an API5L-X52 line pipe steel was evaluated by Charpy V-notch impact test, fracture analysis and transmission electron microscopy. Aging was performed at 250 degree centigrade for 100 to 1000 h. The impact results indicated a significant reduction in the fracture energy and impact toughness as a function of aging time, which were achieved by the scanning electron microscope fractography that showed a decrease in the vol fraction of microvoids by Charpy ductile failure with the aging time, which favored the brittle fracture by transgranular cleavage. The minimum vol fraction of microvoids was reached at 500 h due to the peak aged. The microstructural analysis indicated the precipitation of transgranular iron nano carbides in the aged specimens, which was related to the deterioration of toughness and change in the ductile to brittle behavior. (Author) 15 refs

  6. Study of in vitro degradation of biodegradable polymer based thin ...

    African Journals Online (AJOL)

    GREGORY

    2011-12-16

    Dec 16, 2011 ... treatment of bone fracture costs over Ł 900 million annually in the ... implantation when the cells start to migrate deep into the scaffold (Ma .... DISCUSSION. Figure 8 is ... polymer-based materials proceeds via a surface erosion mechanism. ... materials and the critical thickness above which the degradation ...

  7. First-term Status Report for the Component Operational Experience Degradation and Ageing Programme (CODAP) - 2011-2014

    International Nuclear Information System (INIS)

    2015-04-01

    Structural integrity of piping systems is important for plant safety and operability. In recognition of this, information on degradation and failure of piping components and systems is collected and evaluated by regulatory agencies, international organisations (e.g., OECD/NEA and IAEA) and industry organisations worldwide to provide systematic feedback to reactor regulation and research and development programmes associated with non-destructive examination (NDE) technology, in-service inspection (ISI) programmes, leak-before-break evaluations, risk-informed ISI, and probabilistic safety assessment (PSA) applications involving passive component reliability. Several OECD Member Countries have agreed to establish the OECD/NEA 'Component Operational Experience, Degradation and Ageing Programme' (CODAP) to encourage multilateral co-operation in the collection and analysis of data relating to degradation and failure of metallic piping and non-piping metallic passive components in commercial nuclear power plants. The scope of the data collection includes service-induced wall thinning, part through-wall cracks, through-wall cracks with and without active leakage, and instances of significant degradation of metallic passive components, including piping pressure boundary integrity. The Project is organised under the OECD/NEA Committee on the Safety of Nuclear Installations (CSNI). CODAP is the continuation of the 2002-2011 'OECD/NEA Pipe Failure Data Exchange Project' (OPDE) and the Stress Corrosion Cracking Working Group of the 2006-2010 'OECD/NEA SCC and Cable Ageing project' (SCAP). OPDE was formally launched in May 2002. Upon completion of the 3. Term (May 2011), the OPDE project was officially closed to be succeeded by CODAP. SCAP was enabled by a voluntary contribution from Japan. It was formally launched in June 2006 and officially closed with an international workshop held in Tokyo in May 2010. Majority of the member organizations of the

  8. Degradation in PV Encapsulation Transmittance: An Interlaboratory Study Toward a Climate-Specific Test

    Energy Technology Data Exchange (ETDEWEB)

    Miller, David C.; Hacke, Peter L.; Kempe, Michael D.; Wohlgemuth, John H.; Annigoni, Eleonora; Sculati-Meillaud, Fanny; Ballion, Amal; Kohl, Michael; Bokria, Jayesh G.; Bruckman, Laura S.; French, Roger H.; Burns, David; Phillips, Nancy H.; Feng; Jiangtao; Elliott, Lamont; Scott, Kurt P.; Fowler, Sean; Gu, Xiaohong; Honeker, Christian C.; Khonkar, Hussam; Perret-Aebi, Laure-Emmanuelle; Shioda, Tsy

    2015-06-14

    Reduced optical transmittance of encapsulation resulting from ultraviolet (UV) degradation has frequently been identified as a cause of decreased PV module performance through the life of installations in the field. The present module safety and qualification standards, however, apply short UV doses only capable of examining design robustness or 'infant mortality' failures. Essential information that might be used to screen encapsulation through product lifetime remains unknown. For example, the relative efficacy of xenon-arc and UVA-340 fluorescent sources or the typical range of activation energy for degradation is not quantified. We have conducted an interlaboratory experiment to provide the understanding that will be used towards developing a climate- and configuration-specific (UV) weathering test. Five representative, known formulations of EVA were studied in addition to one TPU material. Replicate laminated silica/polymer/silica specimens are being examined at 14 institutions using a variety of indoor chambers (including Xe, UVA-340, and metal-halide light sources) or field aging. The solar-weighted transmittance, yellowness index, and the UV cut-off wavelength, determined from the measured hemispherical transmittance, are examined to provide understanding and guidance for the UV light source (lamp type) and temperature used in accelerated UV aging tests. Index Terms -- reliability, durability, thermal activation.

  9. Differentially Severe Cognitive Effects of Compromised Cerebral Blood Flow in Aged Mice: Association with Myelin Degradation and Microglia Activation

    Directory of Open Access Journals (Sweden)

    Gilly Wolf

    2017-06-01

    Full Text Available Bilateral common carotid artery stenosis (BCAS models the effects of compromised cerebral blood flow on brain structure and function in mice. We compared the effects of BCAS in aged (21 month and young adult (3 month female mice, anticipating a differentially more severe effect in the older mice. Four weeks after surgery there was a significant age by time by treatment interaction on the radial-arm water maze (RAWM; p = 0.014: on the first day of the test, latencies of old mice were longer compared to the latencies of young adult mice, independent of BCAS. However, on the second day of the test, latencies of old BCAS mice were significantly longer than old control mice (p = 0.049, while latencies of old controls were similar to those of the young adult mice, indicating more severe impairment of hippocampal dependent learning and working memory by BCAS in the older mice. Fluorescence staining of myelin basic protein (MBP showed that old age and BCAS both induced a significant decrease in fluorescence intensity. Evaluation of the number oligodendrocyte precursor cells demonstrated augmented myelin replacement in old BCAS mice (p < 0.05 compared with young adult BCAS and old control mice. While microglia morphology was assessed as normal in young adult control and young adult BCAS mice, microglia of old BCAS mice exhibited striking activation in the area of degraded myelin compared to young adult BCAS (p < 0.01 and old control mice (p < 0.05. These findings show a differentially more severe effect of cerebral hypoperfusion on cognitive function, myelin integrity and inflammatory processes in aged mice. Hypoperfusion may exacerbate degradation initiated by aging, which may induce more severe neuronal and cognitive phenotypes.

  10. Studying DAC capacitor-array degradation in charge-redistribution SAR ADCs

    NARCIS (Netherlands)

    Khan, M.A.; Kerkhoff, Hans G.

    2014-01-01

    In this paper, system-level behavioural models are used to simulate the aging-related degradation effects in the DAC capacitor array of a charge-redistribution successive approximation register (SAR) ADC because of the large calculation time of transistor-level aging simulators. A

  11. In vitro study on the degradation of lithium-doped hydroxyapatite for bone tissue engineering scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaping; Yang, Xu; Gu, Zhipeng; Qin, Huanhuan [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Li, Li [Department of Oncology, The 452 Hospital of Chinese PLA, Chengdu, Sichuan Province 610021 (China); Liu, Jingwang [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Yu, Xixun, E-mail: yuxixun@163.com [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2016-09-01

    Li-doped hydroxyapatite (LiHA) which is prepared through introducing low dose of Li into hydroxyapatite (HA) has been increasingly studied as a bone tissue-engineered scaffold. The degradation properties play a crucial role in the success of long-term implantation of a bone tissue-engineered construct. Herein, the in vitro degradation behaviors of LiHA scaffolds via two approaches were investigated in this study: solution-mediated degradation and osteoblast-mediated degradation. In solution-mediated degradation, after being immersed in simulated body fluid (SBF) for some time, some characteristics of these scaffolds (such as release of ionized lithium and phosphate, pH change, mechanical properties, cytocompatibility and SEM surface characterization) were systematically tested. A similar procedure was also employed to research the degradation behaviors of LiHA scaffolds in osteoblast-mediated degradation. The results suggested that the degradation in SBF and degradation in culture medium with cell existed distinguishing mechanisms. LiHA scaffolds were degraded via a hydrolytic mechanism when they were soaked in SBF. Upon degradation, an apatite precipitation (layer) was formed on the surfaces of scaffolds. While a biological mechanism was presented for the degradation of scaffolds in cell-mediated degradation. Compared with pure HA, LiHA scaffolds had a better effect on the growth of osteoblast cells, meanwhile, the release amount of PO{sub 4}{sup 3−} in a degradation medium indicated that osteoblasts could accelerate the degradation of LiHA due to the more physiological activities of osteoblast. According to the results from compressive strength test, doping Li into HA could enhance the strength of HA. Moreover, the results from MTT assay and SEM observation showed that the degradation products of LiHA scaffolds were beneficial to the proliferation of osteoblasts. The results of this research can provide the theoretical basis for the clinical application of Li

  12. Exploring the microbiota dynamics related to vegetable biomasses degradation and study of lignocellulose-degrading bacteria for industrial biotechnological application

    Science.gov (United States)

    Ventorino, Valeria; Aliberti, Alberto; Faraco, Vincenza; Robertiello, Alessandro; Giacobbe, Simona; Ercolini, Danilo; Amore, Antonella; Fagnano, Massimo; Pepe, Olimpia

    2015-02-01

    The aims of this study were to evaluate the microbial diversity of different lignocellulosic biomasses during degradation under natural conditions and to isolate, select, characterise new well-adapted bacterial strains to detect potentially improved enzyme-producing bacteria. The microbiota of biomass piles of Arundo donax, Eucalyptus camaldulensis and Populus nigra were evaluated by high-throughput sequencing. A highly complex bacterial community was found, composed of ubiquitous bacteria, with the highest representation by the Actinobacteria, Proteobacteria, Bacteroidetes and Firmicutes phyla. The abundances of the major and minor taxa retrieved during the process were determined by the selective pressure produced by the lignocellulosic plant species and degradation conditions. Moreover, cellulolytic bacteria were isolated using differential substrates and screened for cellulase, cellobiase, xylanase, pectinase and ligninase activities. Forty strains that showed multienzymatic activity were selected and identified. The highest endo-cellulase activity was seen in Promicromonospora sukumoe CE86 and Isoptericola variabilis CA84, which were able to degrade cellulose, cellobiose and xylan. Sixty-two percent of bacterial strains tested exhibited high extracellular endo-1,4-ß-glucanase activity in liquid media. These approaches show that the microbiota of lignocellulosic biomasses can be considered an important source of bacterial strains to upgrade the feasibility of lignocellulose conversion for the `greener' technology of second-generation biofuels.

  13. Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel

    OpenAIRE

    Akhlaghi, Shahin; Pourrahimi, A. M.; Christian, Sjöstedt; Martin, Bellander; Mikael S., Hedenqvist; Ulf W., Gedde

    2017-01-01

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the cross...

  14. Applications and extensions of degradation modeling

    International Nuclear Information System (INIS)

    Hsu, F.; Subudhi, M.; Samanta, P.K.; Vesely, W.E.

    1991-01-01

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs

  15. Applications and extensions of degradation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, F.; Subudhi, M.; Samanta, P.K. [Brookhaven National Lab., Upton, NY (United States); Vesely, W.E. [Science Applications International Corp., Columbus, OH (United States)

    1991-12-31

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

  16. Applications and extensions of degradation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, F.; Subudhi, M.; Samanta, P.K. (Brookhaven National Lab., Upton, NY (United States)); Vesely, W.E. (Science Applications International Corp., Columbus, OH (United States))

    1991-01-01

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

  17. Preventive maintenance optimization for a stochastically degrading system with a random initial age

    International Nuclear Information System (INIS)

    Sidibe, I.B.; Khatab, A.; Diallo, C.; Kassambara, A.

    2017-01-01

    This paper investigates the optimal age replacement policy for used systems, such as second-hand products, which start their second life-cycle in a more severe environment with an initial age that is uncertain. This uncertain age is modelled as a random variable following continuous probability distributions. A mathematical model is developed to minimize the total expected cost per unit of time for these systems on an infinite time horizon. Optimality and existence conditions for a unique optimal solution are derived and used in a numerical procedure to solve the problem. Numerical experiments are provided to demonstrate the added value and the impacts of the random initial age on the optimal replacement policy.

  18. Degradation of herbicides in shallow Danish aquifers - an integrated laboratory and field study

    DEFF Research Database (Denmark)

    Albrechtsen, Hans-Jørgen; Mills, M.; Aamand, J.

    2001-01-01

    Degradation of pesticides in aquifers has been evaluated based on a number of co-ordinated field and laboratory studies carried out in Danish aquifers. These studies included investigations of vertical and horizontal variability in degradation rates from the vadose zone to an aquifer, the effects...

  19. Evaluation of the influence of fluoroquinolone chemical structure on stability: forced degradation and in silico studies

    Directory of Open Access Journals (Sweden)

    André Valle de Bairros

    2018-05-01

    Full Text Available ABSTRACT Fluoroquinolones are a known antibacterial class commonly used around the world. These compounds present relative stability and they may show some adverse effects according their distinct chemical structures. The chemical hydrolysis of five fluoroquinolones was studied using alkaline and photolytic degradation aiming to observe the differences in molecular reactivity. DFT/B3LYP-6.31G* was used to assist with understanding the chemical structure degradation. Gemifloxacin underwent degradation in alkaline medium. Gemifloxacin and danofloxacin showed more degradation perceptual indices in comparison with ciprofloxacin, enrofloxacin and norfloxacin in photolytic conditions. Some structural features were observed which may influence degradation, such as the presence of five member rings attached to the quinolone ring and the electrostatic positive charges, showed in maps of potential electrostatic charges. These measurements may be used in the design of effective and more stable fluoroquinolones as well as the investigation of degradation products from stress stability assays.

  20. Study of PCB degradation in real contaminated soil

    Czech Academy of Sciences Publication Activity Database

    Ryšlavá, E.; Krejčík, Zdeněk; Macek, Tomáš; Nováková, H.; Demnerová, K.; Macková, M.

    2003-01-01

    Roč. 2003, č. 12 (2003), s. 296-301 ISSN 1018-4619 R&D Projects: GA MŠk LN00A079; GA ČR GA526/01/1292 Grant - others:GA EU(XE) QLK3-CT-2001-00101 Institutional research plan: CEZ:AV0Z4055905; CEZ:AV0Z5052915 Keywords : Phytoremediation * rhizoremediation * PCB degradation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 0.325, year: 2003

  1. Mechanical property degradation and microstructural evolution of cast austenitic stainless steels under short-term thermal aging

    Science.gov (United States)

    Lach, Timothy G.; Byun, Thak Sang; Leonard, Keith J.

    2017-12-01

    Mechanical testing and microstructural characterization were performed on short-term thermally aged cast austenitic stainless steels (CASS) to understand the severity and mechanisms of thermal-aging degradation experienced during extended operation of light water reactor (LWR) coolant systems. Four CASS materials-CF3, CF3M, CF8, and CF8M-were thermally aged for 1500 h at 290 °C, 330 °C, 360 °C, and 400 °C. All four alloys experienced insignificant change in strength and ductility properties but a significant reduction in absorbed impact energy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α‧, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M23C6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on chemical composition, particularly the concentration of C and Mo, and aging temperature. The low C, high Mo CF3M alloys experienced the most spinodal decomposition and G-phase precipitation coinciding the largest reduction in impact properties.

  2. Preparation of Diatomite Supported Nano Zinc Oxide Composite Photocatalytic Material and Study on its Formaldehyde Degradation

    Science.gov (United States)

    Xiao, Liguang; Pang, Bo

    2017-09-01

    This experiment used zinc nitrate as precursor, ethanol as solvent and polyethylene glycol as dispersant, diatomite as carrier, diatomite loaded nano Zinc Oxide was prepared by sol-gel method, in addition, the formaldehyde degradation was studied by two kinds of experimental methods: preparation and loading, preparation and post loading, The samples were characterized by SEM, XRD, BET and IR. Experimental results showed that: Diatomite based nano Zinc Oxide had a continuous adsorption and degradation of formaldehyde, formaldehyde gas with initial concentration was 0.7mg/m3, after 36h degradation, the concentration reached 0.238mg/m3, the degradation rate reached to 66%.

  3. Degradation of stainless castings. A literature study; Degradering av rostfritt gjutgods. En litteraturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Norring, K. [Studsvik Material AB, Nykoeping (Sweden)

    1995-10-01

    Duplex cast stainless steels, containing mainly austenite and some ferrite, is used for different components in light water reactors. These alloys have good mechanical properties, good weldability, and they are resistant to intergranular stress corrosion cracking (IGSCC). Examples of components where cast duplex stainless steel is used are pump housings, valves and pipe elbows. A model for the aging/embrittlement of these materials when used in light water reactors has been developed. The model is based on regression of a large data matrix. It is mainly the impact energy (Charpy V) that has been regarded. The model only requires knowledge of the chemical composition of the material but the prediction can be improved if additional data like initial impact properties and measured ferrite content are available. The model is also capable of predicting fracture toughness. The susceptibility to IGSCC in BWR environment is primarily determined by the amount of ferrite and the carbon content of the material. When the amount of ferrite exceeds 12%, IGSCC has not been observed regardless of the carbon content. At carbon contents lower than 0.035% in weld-sensitized material IGSCC was not observed regardless of the ferrite content. Data for corrosion fatigue in primary PWR and BWR environment are available. Under BWR conditions the crack propagation rate is decreased with decreasing corrosion potential, consequently also with decreasing oxygen content of the water. Some areas have been identified where additional work is needed. In all cases the efforts should focus on characterizing cast duplex stainless steel components removed from Swedish reactors. The characterization should include: Microstructure and chemical analysis, susceptibility to IGSCC, and a comparison with existing models for embrittlement. 24 refs, 12 figs.

  4. Experimental and modeling study of Portland cement paste degradation in boric acid

    International Nuclear Information System (INIS)

    Benakli, A.; Chomat, L.; Le Bescop, P.; Wall, J.

    2015-01-01

    In the framework of Spent Fuel Pools (SFP) lifetime studies, an investigation of the Portland cement degradation in boric acid has been requested by the Electric Power Research Institute. The main goal of this study is to identify the physico-chemical degradation mechanisms involved in boric acid media. Both experimental and modeling approaches are considered. Concerning degradation experiments, sample of cement paste are immersed during three and nine months in a boric acid solution at 2400 ppm that is periodically renewed. Boric acid concentration has been chosen to be representative of SFP solution. Results will be confronted with reactive transport numerical calculations performed by the reactive transport code HYTEC associated with a dedicated extended database called Thermoddem. The analysis of degradation solution revealed a main ions release mechanism driven by diffusion especially for calcium, nitrate, sodium and sulfate. Leaching behavior of magnesium seems to be more complex. Decalcification is the major degradation process involved, even if a non-negligible contribution of further cations (Mg 2+ , Na + ) and anions (SO 4 2- ) has been noticed. Analysis of degradation soution also revealed that kinetic of Portland cement paste degradation in boric acid is higher than in pure water, regarding the degraded depths measured and calcium leaching rate. This observation has been confirmed by solid characterization. Microstructure analysis of degraded Portland cement paste showed a global porosity increase in the degraded zone that might be mainly attributed to Portlandite dissolution. An Ettringite reprecipitation in the degraded zone has been suspected but could also be Ettringite-like phases containing boron. The analysis techniques used did not allow us to differentiate it, and no others specific mineral phases containing boron has been identified. Profile pattern by XRD analysis allowed us to identify four zones composing the degraded Portland cement paste

  5. Inhibition and kinetic studies of lignin degrading enzymes of Ganoderma boninense by naturally occurring phenolic compounds.

    Science.gov (United States)

    Surendran, Arthy; Siddiqui, Yasmeen; Saud, Halimi Mohd; Ali, Nusaibah Syd; Manickam, Sivakumar

    2018-05-22

    Lignolytic (Lignin degrading) enzyme, from oil palm pathogen Ganoderma boninense Pat. (Syn G. orbiforme (Ryvarden), is involved in the detoxification and the degradation of lignin in the oil palm and is the rate-limiting step in the infection process of this fungus. Active inhibition of lignin degrading enzymes secreted by G. boninense by various naturally occurring phenolic compounds and estimation of efficiency on pathogen suppression was aimed at. In our work, ten naturally occurring phenolic compounds were evaluated for their inhibitory potential towards the lignolytic enzymes of G.boninense. Additionally, the lignin degrading enzymes were characterised. Most of the peholic compounds exhibited an uncompetitive inhibition towards the lignin degrading enzymes. Benzoic acid was the superior inhibitor to the production of lignin degrading enzymes, when compared between the ten phenolic compounds. The inhibitory potential of the phenolic compounds toward the lignin degrading enzymes are higher than that of the conventional metal ion inhibitor. The lignin degrading enzymes were stable in a wide range of pH but were sensitive to higher to temperature. The study demonstrated the inhibitor potential of ten naturally occurring phenolic compounds toward the lignin degrading enzymes of G. boninense with different efficacies. The study has shed a light towards a new management strategy to control BSR in oil palm. It serves as replacement for the existing chemical control. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. FRAMEWORK FOR STRUCTURAL ONLINE HEALTH MONITORING OF AGING AND DEGRADATION OF SECONDARY PIPING SYSTEMS DUE TO SOME ASPECTS OF EROSION

    Energy Technology Data Exchange (ETDEWEB)

    Gribok, Andrei V.; Agarwal, Vivek

    2017-06-01

    This paper describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants (NPPs). The paper also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system, which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk-informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. Furthermore, of the operations and maintenance costs in U.S. plants, approximately 80% are labor costs. To address the issue of rising operating costs and economic viability, in 2017, companies that operate the national nuclear energy fleet started the Delivering the Nuclear Promise Initiative, which is a 3 year program aimed at maintaining operational focus, increasing value, and improving efficiency. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at

  7. Hydrothermal degradation of a 3Y-TZP translucent dental ceramic: A comparison of numerical predictions with experimental data after 2 years of aging.

    Science.gov (United States)

    Cattani-Lorente, Maria; Durual, Stéphane; Amez-Droz, Michel; Wiskott, H W Anselm; Scherrer, Susanne S

    2016-03-01

    The purpose of the study was to assess the hydrothermal resistance of a translucent zirconia with two clinical relevant surface textures by means of accelerated tests (LTD) and to compare predicted monoclinic fractions with experimental values measured after two years aging at 37°C. Polished (P) and ground (G) specimens were subjected to hydrothermal degradation by exposure to water steam at different temperatures and pressures. The t-m phase transformation was quantified by grazing incidence X-ray diffraction (GIXDR). The elastic modulus and hardness before- and after LTD were determined by nanoindentation. G specimens presented a better resistance to hydrothermal degradation than P samples. Activation energies of 89 and 98kJ/mol and b coefficients of 2.0×10(-5) and 1.8×10(-6) were calculated for P and G samples respectively. The coefficients were subsequently used to predict transformed monoclinic fractions at 37°C. A good correlation was found between the predicted values and the experimental data obtained after aging at 37°C during 2 years. Hydrothermal degradation led to a significant decrease of the elastic moduli and hardness in both groups. The dependency of the t-m phase transformation rate on temperature must be determined to accurately predict the hydrothermal behavior of the zirconia ceramics at oral temperatures. The current prevailing assumption, that 5h aging at 134°C corresponds to 15-20 years at 37°C, will underestimate the transformed fraction of the translucent ceramic at 37°C. In this case, the mechanical surface treatment influences the ceramic's transformability. While mild grinding could potentially retard the hydrothermal transformation, polishing after occlusal adjustment is recommended to prevent wear of the antagonist teeth and maintain structural strength. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Study of polyurethanes ageing offshore

    Energy Technology Data Exchange (ETDEWEB)

    Aquino, Fabio G.; Sheldrake, Terry; Clevelario, Judimar; Pires, Fabio [Wellstream International, Panama City, FL (United States); Coutinho, Fernanda M.B. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2008-07-01

    The oil industry is one of the sectors with the highest number of production systems employing high technology. Brazil is worldwide renowned as a leader in oil and gas extraction in deep and ultra deep water. Inside the production chain, a great part the oil and gas produced is conveyed through flexible pipelines that connect the production wells to the platforms. There are two segments of these lines that receive different names according to their application characteristics. When the pipes are laid on the seabed in a static service condition, are called Flow lines and when they raise from the seabed to the platform in a dynamic service condition, are called Risers. The pipes designed for dynamic applications are equipped with Bend Stiffeners, components with conical form and in general with urethane basis, which has the function of providing a smooth stiffness transition between the flexible structure of the pipes and an extremely rigid structure, the platform, not allowing that this component infringes their minimum operation Bend Radius. According to Caire, the proper compression of curvature stiffeners and the material used in its manufacture is becoming increasingly important in industry due to its growing use and the occurrence of failures that have been recorded in recent years. This paper discusses the changes in the mechanical properties of polyurethanes by the hydrolysis during accelerated ageing, reaction of water with functional groups of the polymer chain, as well as mass variation, considering that these materials are designed for a service life exceeding twenty years for operation in water. (author)

  9. Biocompatibility of degradable biomaterials : a study on the factors determining the inflammatory response against degradable polymers

    NARCIS (Netherlands)

    Lam, King Hong

    1992-01-01

    The study reported in this thesis was undertaken to obtain more insight in the role of various factors determining the outcome of the interaction between biodegradable polymers and the host in which they are implanted. In the end, the outcome of this interaction determines the success or failure of

  10. Land degradation in the Sudan Savanna of Ghana: A case study in ...

    African Journals Online (AJOL)

    Land degradation in the area is the result of interaction between the physical and human environments. Physical environmental characteristics influencing land degradation include soil texture, topography and rainfall. The soils in the study area are developed over granite and Birrimian phyllite. In the granitic areas soil ...

  11. Studies on Post-Irradiation DNA Degradation in Micrococcus Radiodurans, Strain RII51

    DEFF Research Database (Denmark)

    Auda, H.; Emborg, C.

    1973-01-01

    The influence of irradiation condition on post-irradiation DNA degradation was studied in a radiation resistant mutant of M. radiodurans, strain ${\\rm R}_{{\\rm II}}5$. After irradiation with 1 Mrad or higher more DNA is degraded in cells irradiated in wet condition than in cells irradiated with t...

  12. Enzymatic degradation studies of xylogalacturonans from apple and potato, using xylogalacturonan hydrolase

    NARCIS (Netherlands)

    Zandleven, J.S.; Beldman, G.; Bosveld, M.; Schols, H.A.; Voragen, A.G.J.

    2006-01-01

    Action of xylogalacturonan hydrolase (XGH) towards xylogalacturonan (XGA) present in the alkali saponified ¿modified hairy regions¿ from potato and apple pectin was studied. Analysis of enzymatic degradation products from XGA in these complex pectins demonstrated that the degradable

  13. Human resilience in a degrading environment: A case study in China

    NARCIS (Netherlands)

    Haaften, A.J.; Yu, Z.R.; Vijver, van den F.J.R.

    2004-01-01

    Psychological aspects of environmental degradation were studied among 753 Chinese farmers. A good fit was found for a structural equation model postulating a relationship between various input variables (i.e. environmental degradation, socio-economic status, education, coping, and locus of control),

  14. Degradation study of pesticides used in Dourados-MS

    Directory of Open Access Journals (Sweden)

    Virgilio Vieira de Olival

    2012-10-01

    Full Text Available The intensive use and irregular disposal of pesticides in agriculture has caused serious environmental and health problems. In this work was evaluated the efficiency of UV and some advanced oxidation processes involving photo-Fenton reaction, O3 and O3/UV for the treatment of aqueous solutions containing commercial and standard pesticides. The results showed that the combination of UV radiation in alkaline means with O3 significantly increased the efficiency of the process of degradation and the photo-Fenton system is a promising alternative for the treatment of effluents containing pesticides.

  15. Oxidative degradation of alternative gasoline oxygenates in aqueous solution by ultrasonic irradiation: Mechanistic study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Duk Kyung, E-mail: dkim@aum.edu [Department of Physical Science, Auburn University Montgomery, Montgomery, AL 36117 (United States); O' Shea, Kevin E., E-mail: osheak@fiu.edu [Department of Chemistry and Biochemistry, Florida International University, University Park, Miami, FL 33199 (United States); Cooper, William J. [Department of Civil and Environmental Engineering, Urban Water Research Center, University of California Irvine, Irvine, CA 92697-2175 (United States)

    2012-07-15

    Widespread pollution has been associated with gasoline oxygenates of branched ethers methyl tert-butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), and tert-amyl ether (TAME) which enter groundwater. The contaminated plume develops rapidly and treatment for the removal/destruction of these ethers is difficult when using conventional methods. Degradation of MTBE, with biological methods and advanced oxidation processes, are rather well known; however, fewer studies have been reported for degradation of alternative oxygenates. Degradation of alternative gasoline oxygenates (DIPE, ETBE, and TAME) by ultrasonic irradiation in aqueous oxygen saturation was investigated to elucidate degradation pathways. Detailed degradation mechanisms are proposed for each gasoline oxygenate. The common major degradation pathways are proposed to involve abstraction of {alpha}-hydrogen atoms by hydroxyl radicals generated during ultrasound cavitation and low temperature pyrolytic degradation of ETBE and TAME. Even some of the products from {beta}-H abstraction overlap with those from high temperature pyrolysis, the effect of {beta}-H abstraction was not shown clearly from product study because of possible 1,5 H-transfer inside cavitating bubbles. Formation of hydrogen peroxide and organic peroxides was also determined during sonolysis. These data provide a better understanding of the degradation pathways of gasoline oxygenates by sonolysis in aqueous solutions. The approach may also serve as a model for others interested in the details of sonolysis. - Highlights: Black-Right-Pointing-Pointer Gasoline oxygenates (ETBE, TAME, DIPE) were completely degraded after 6 hours under ultrasonic irradiation in O{sub 2} saturation. Black-Right-Pointing-Pointer The major degradation pathways were proposed to involve abstraction of {alpha}-hydrogen atoms by hydroxyl radicals and low temperature pyrolytic degradation. Black-Right-Pointing-Pointer The effect of {beta

  16. Aging study of boiling water reactor high pressure injection systems

    International Nuclear Information System (INIS)

    Conley, D.A.; Edson, J.L.; Fineman, C.F.

    1995-03-01

    The purpose of high pressure injection systems is to maintain an adequate coolant level in reactor pressure vessels, so that the fuel cladding temperature does not exceed 1,200 degrees C (2,200 degrees F), and to permit plant shutdown during a variety of design basis loss-of-coolant accidents. This report presents the results of a study on aging performed for high pressure injection systems of boiling water reactor plants in the United States. The purpose of the study was to identify and evaluate the effects of aging and the effectiveness of testing and maintenance in detecting and mitigating aging degradation. Guidelines from the United States Nuclear Regulatory Commission's Nuclear Plant Aging Research Program were used in performing the aging study. Review and analysis of the failures reported in databases such as Nuclear Power Experience, Licensee Event Reports, and the Nuclear Plant Reliability Data System, along with plant-specific maintenance records databases, are included in this report to provide the information required to identify aging stressors, failure modes, and failure causes. Several probabilistic risk assessments were reviewed to identify risk-significant components in high pressure injection systems. Testing, maintenance, specific safety issues, and codes and standards are also discussed

  17. Degradation of polycyclic aromatic hydrocarbons (PAHs) in an aged coal tar contaminated soil under in-vessel composting conditions

    International Nuclear Information System (INIS)

    Antizar-Ladislao, Blanca; Lopez-Real, Joe; Beck, Angus James

    2006-01-01

    In-vessel composting of polycyclic aromatic hydrocarbons (PAHs) present in contaminated soil from a manufactured gas plant site was investigated over 98 days using laboratory-scale in-vessel composting reactors. The composting reactors were operated at 18 different operational conditions using a 3-factor factorial design with three temperatures (T, 38 deg. C, 55 deg. C and 70 deg. C), four soil to green waste ratios (S:GW, 0.6:1, 0.7:1, 0.8:1 and 0.9:1 on a dry weight basis) and three moisture contents (MC, 40%, 60% and 80%). PAH losses followed first order kinetics reaching 0.015 day -1 at optimal operational conditions. A factor analysis of the 18 different operational conditions under investigation indicated that the optimal operational conditions for degradation of PAHs occurred at MC 60%, S:GW 0.8:1 and T 38 deg. C. Thus, it is recommended to maintain operational conditions during in-vessel composting of PAH-solid waste close to these values. - Maximum degradation of PAHs in an aged coal tar contaminated soil can be achieved using optimal operational conditions during composting

  18. Kinetic and mechanistic study of microcystin-LR degradation by nitrous acid under ultraviolet irradiation

    International Nuclear Information System (INIS)

    Ma, Qingwei; Ren, Jing; Huang, Honghui; Wang, Shoubing; Wang, Xiangrong; Fan, Zhengqiu

    2012-01-01

    Highlights: ► For the first time, degradation of MC-LR by nitrous acid under UV 365 nm was discovered. ► The effects of factors on MC-LR degradation were analyzed based on kinetic study. ► Mass spectrometry was applied for identification of intermediates and products. ► Special intermediates involved in this study were identified. ► Degradation mechanisms were proposed according to the results of LC–MS analysis. - Abstract: Degradation of microcystin-LR (MC-LR) in the presence of nitrous acid (HNO 2 ) under irradiation of 365 nm ultraviolet (UV) was studied for the first time. The influence of initial conditions including pH value, NaNO 2 concentration, MC-LR concentration and UV intensity were studied. MC-LR was degraded in the presence of HNO 2 ; enhanced degradation of MC-LR was observed with 365 nm UV irradiation, caused by the generation of hydroxyl radicals through the photolysis of HNO 2 . The degradation processes of MC-LR could well fit the pseudo-first-order kinetics. Mass spectrometry was applied for identification of the byproducts and the analysis of degradation mechanisms. Major degradation pathways were proposed according to the results of LC–MS analysis. The degradation of MC-LR was initiated via three major pathways: attack of hydroxyl radicals on the conjugated carbon double bonds of Adda, attack of hydroxyl radicals on the benzene ring of Adda, and attack of nitrosonium ion on the benzene ring of Adda.

  19. Kinetic and mechanistic study of microcystin-LR degradation by nitrous acid under ultraviolet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Qingwei; Ren, Jing [Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Huang, Honghui [Key Laboratory of Fisheries Ecology Environment, Ministry of Agriculture, Guangzhou 510300 (China); Wang, Shoubing [Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Wang, Xiangrong, E-mail: xrxrwang@vip.sina.com [Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Fan, Zhengqiu, E-mail: zhqfan@fudan.edu.cn [Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer For the first time, degradation of MC-LR by nitrous acid under UV 365 nm was discovered. Black-Right-Pointing-Pointer The effects of factors on MC-LR degradation were analyzed based on kinetic study. Black-Right-Pointing-Pointer Mass spectrometry was applied for identification of intermediates and products. Black-Right-Pointing-Pointer Special intermediates involved in this study were identified. Black-Right-Pointing-Pointer Degradation mechanisms were proposed according to the results of LC-MS analysis. - Abstract: Degradation of microcystin-LR (MC-LR) in the presence of nitrous acid (HNO{sub 2}) under irradiation of 365 nm ultraviolet (UV) was studied for the first time. The influence of initial conditions including pH value, NaNO{sub 2} concentration, MC-LR concentration and UV intensity were studied. MC-LR was degraded in the presence of HNO{sub 2}; enhanced degradation of MC-LR was observed with 365 nm UV irradiation, caused by the generation of hydroxyl radicals through the photolysis of HNO{sub 2}. The degradation processes of MC-LR could well fit the pseudo-first-order kinetics. Mass spectrometry was applied for identification of the byproducts and the analysis of degradation mechanisms. Major degradation pathways were proposed according to the results of LC-MS analysis. The degradation of MC-LR was initiated via three major pathways: attack of hydroxyl radicals on the conjugated carbon double bonds of Adda, attack of hydroxyl radicals on the benzene ring of Adda, and attack of nitrosonium ion on the benzene ring of Adda.

  20. Pressurized Hot Water Extraction of anthocyanins from red onion: A study on extraction and degradation rates

    Energy Technology Data Exchange (ETDEWEB)

    Petersson, Erik V.; Liu Jiayin; Sjoeberg, Per J.R.; Danielsson, Rolf [Uppsala University, Department of Physical and Analytical Chemistry, P.O. Box 599, SE-751 24, Uppsala (Sweden); Turner, Charlotta, E-mail: Charlotta.Turner@kemi.uu.se [Uppsala University, Department of Physical and Analytical Chemistry, P.O. Box 599, SE-751 24, Uppsala (Sweden)

    2010-03-17

    Pressurized Hot Water Extraction (PHWE) is a quick, efficient and environmentally friendly technique for extractions. However, when using PHWE to extract thermally unstable analytes, extraction and degradation effects occur at the same time, and thereby compete. At first, the extraction effect dominates, but degradation effects soon take over. In this paper, extraction and degradation rates of anthocyanins from red onion were studied with experiments in a static batch reactor at 110 deg. C. A total extraction curve was calculated with data from the actual extraction and degradation curves, showing that more anthocyanins, 21-36% depending on the species, could be extracted if no degradation occurred, but then longer extraction times would be required than those needed to reach the peak level in the apparent extraction curves. The results give information about the different kinetic processes competing during an extraction procedure.

  1. Kinetic studies on the degradation of crystal violet by the Fenton oxidation process.

    Science.gov (United States)

    Wu, H; Fan, M M; Li, C F; Peng, M; Sheng, L J; Pan, Q; Song, G W

    2010-01-01

    The degradation of dye crystal violet (CV) by Fenton oxidation process was investigated. The UV-Vis spectrogram has shown that CV can be degraded effectively by Fenton oxidation process. Different system variables namely initial H(2)O(2) concentration, initial Fe(2 + ) concentration and reaction temperature, which have effect on the degradation of CV by Fenton oxidation process, have been studied systematically. The degradation kinetics of CV was also elucidated based on the experimental data. The degradation of CV obeys the first-order reaction kinetics. The kinetic model can be described as k=1.5 exp(-(7.5)/(RT))[H(2)O(2)](0)(0.8718)[Fe(2+)](0)(0.5062). According to the IR spectrogram, it is concluded that the benzene ring of crystal violet has been destroyed by Fenton oxidation. The result will be useful in treating dyeing wastewater containing CV by Fenton oxidation process.

  2. Experimental study of the oxidative degradation of PBX 9501 and its components

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, Michael R. [Department of Chemistry, Union University, Jackson, Tennessee (United States); Kress, Joel D. [Theoretical Division (T-12, MS B268), Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Lightfoot, J.M.; Russel, Bobby G.; Rodin, Wayne A.; Woods, Lorelei [Babcock and Wilcox Technical Services Pantex, LLC (B and W Pantex), Amarillo, Texas (United States)

    2008-06-15

    The results of the constituent aging study (CAS) are given, where low-temperature (T<64 C) aging experiments were performed on over 1100 closed-container samples of various combinations of the components of the plastic-bonded explosive PBX 9501. Experiments were performed on the various combinations both in the absence and presence of free-radical stabilizers. The product gases were identified and quantified as a function of aging time. The gas data show diverse chemistry between CAS samples and initial linear increases in product gas formation. Temperature analysis of the initial production rates of gas products shows straight Arrhenius plots. The extracted activation energies and frequency factors for the formation of the individual gas products yield a single linear kinetic compensation plot suggesting a common degradation pathway for PBX 9501 and combinations of constituents that contained nitroplasticizer (a eutectic mixture of bis-2,2-dintropropyl acetal and bis-2,2-dintropropyl formal). (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  3. 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)

  4. Aging studies in atomic bomb survivors

    International Nuclear Information System (INIS)

    Belsky, J.L.; Moriyama, I.M.; Fujita, Shoichiro; Kawamoto, Sadahisa.

    1979-07-01

    Although the studies of the effect of ionizing radiation on atomic bomb survivors have not produced any evidence of radiation-induced aging, there have been studies on experimental animals and man which suggest accelerated aging after exposure to ionizing radiation. To determine if certain physiologic functions could be related to exposure to ionizing radiation, a battery of age-related tests was given at the time of the physical examinations at ABCC. Some 11,351 persons were given these non-invasive age-related tests. The results were essentially negative. Until a satisfactory operational definition of biologic or physiologic age is developed, the administration of functional tests as a measure of aging does not seem justified. (author)

  5. Study of stiffness and bearing capacity degradation of reinforced concrete beams under constant-amplitude fatigue.

    Science.gov (United States)

    Liu, Fangping; Zhou, Jianting; Yan, Lei

    2018-01-01

    For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous

  6. Aging studies in atomic bomb survivors

    International Nuclear Information System (INIS)

    Belsky, J.L.; Moriyama, I.M.; Fujita, Seiichiro; Kawamoto, Sadahisa.

    1980-01-01

    Though acceleration of aging induced by radiation could not be demonstrated in many investigations on delayed effects of ionizing radiation on a-bomb survivors, studies on acceleration of aging after the exposure to ionizing radiation in human and animals have been carried out. To investigate whether physiological function was related to the exposure to ionizing radiation, a series of examinations concerning age was carried out at the time of general health examinations at ABCC. Simple examinations concerning aging were carried out on 11,351 a-bomb survivors, but the result was essentially negative. If biological or physiological age was defined clearly, the results of functional test would be used as criterion of aging. (Tsunoda, M.)

  7. Kinetic and mechanistic study of microcystin-LR degradation by nitrous acid under ultraviolet irradiation.

    Science.gov (United States)

    Ma, Qingwei; Ren, Jing; Huang, Honghui; Wang, Shoubing; Wang, Xiangrong; Fan, Zhengqiu

    2012-05-15

    Degradation of microcystin-LR (MC-LR) in the presence of nitrous acid (HNO(2)) under irradiation of 365nm ultraviolet (UV) was studied for the first time. The influence of initial conditions including pH value, NaNO(2) concentration, MC-LR concentration and UV intensity were studied. MC-LR was degraded in the presence of HNO(2); enhanced degradation of MC-LR was observed with 365nm UV irradiation, caused by the generation of hydroxyl radicals through the photolysis of HNO(2). The degradation processes of MC-LR could well fit the pseudo-first-order kinetics. Mass spectrometry was applied for identification of the byproducts and the analysis of degradation mechanisms. Major degradation pathways were proposed according to the results of LC-MS analysis. The degradation of MC-LR was initiated via three major pathways: attack of hydroxyl radicals on the conjugated carbon double bonds of Adda, attack of hydroxyl radicals on the benzene ring of Adda, and attack of nitrosonium ion on the benzene ring of Adda. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. 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.

  9. Some Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository Study (The Yucca Mountain Project)

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua; P. Pasupathi; N. Brown; K. Mon

    2005-09-19

    The safe disposal of radioactive waste requires that the waste be isolated from the environment until radioactive decay has reduced its toxicity to innocuous levels for plants, animals, and humans. All of the countries currently studying the options for disposing of high-level nuclear waste (HLW) have selected deep geologic formations to be the primary barrier for accomplishing this isolation. In U.S.A., the Nuclear Waste Policy Act of 1982 (as amended in 1987) designated Yucca Mountain in Nevada as the potential site to be characterized for high-level nuclear waste (HLW) disposal. Long-term containment of waste and subsequent slow release of radionuclides into the geosphere will rely on a system of natural and engineered barriers including a robust waste containment design. The waste package design consists of a highly corrosion resistant Ni-based Alloy 22 cylindrical barrier surrounding a Type 316 stainless steel inner structural vessel. The waste package is covered by a mailbox-shaped drip shield composed primarily of Ti Grade 7 with Ti Grade 24 structural support members. The U.S. Yucca Mountain Project has been studying and modeling the degradation issues of the relevant materials for some 20 years. This paper reviews the state-of-the-art understanding of the degradation processes based on the past 20 years studies on Yucca Mountain Project (YMP) materials degradation issues with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the 10,000 years regulatory period. This paper provides an overview of the current understanding of the likely degradation behavior of the waste package and drip shield in the repository after the permanent closure of the facility. The degradation scenario discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced

  10. Some Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository Study (The Yucca Mountain Project)

    International Nuclear Information System (INIS)

    Hua, F.; Pasupathi, P.; Brown, N.; Mon, K.

    2005-01-01

    The safe disposal of radioactive waste requires that the waste be isolated from the environment until radioactive decay has reduced its toxicity to innocuous levels for plants, animals, and humans. All of the countries currently studying the options for disposing of high-level nuclear waste (HLW) have selected deep geologic formations to be the primary barrier for accomplishing this isolation. In U.S.A., the Nuclear Waste Policy Act of 1982 (as amended in 1987) designated Yucca Mountain in Nevada as the potential site to be characterized for high-level nuclear waste (HLW) disposal. Long-term containment of waste and subsequent slow release of radionuclides into the geosphere will rely on a system of natural and engineered barriers including a robust waste containment design. The waste package design consists of a highly corrosion resistant Ni-based Alloy 22 cylindrical barrier surrounding a Type 316 stainless steel inner structural vessel. The waste package is covered by a mailbox-shaped drip shield composed primarily of Ti Grade 7 with Ti Grade 24 structural support members. The U.S. Yucca Mountain Project has been studying and modeling the degradation issues of the relevant materials for some 20 years. This paper reviews the state-of-the-art understanding of the degradation processes based on the past 20 years studies on Yucca Mountain Project (YMP) materials degradation issues with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the 10,000 years regulatory period. This paper provides an overview of the current understanding of the likely degradation behavior of the waste package and drip shield in the repository after the permanent closure of the facility. The degradation scenario discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced

  11. On the Influence of the Sample Absorptivity when Studying the Thermal Degradation of Materials

    Directory of Open Access Journals (Sweden)

    Pascal Boulet

    2015-08-01

    Full Text Available The change in absorptivity during the degradation process of materials is discussed, and its influence as one of the involved parameters in the degradation models is studied. Three materials with very different behaviors are used for the demonstration of its role: a carbon composite material, which is opaque, almost grey, a plywood slab, which is opaque and spectral-dependent and a clear PMMA slab, which is semitransparent. Data are analyzed for virgin and degraded materials at different steps of thermal degradation. It is seen that absorptivity and emissivity often reach high values in the range of 0.90–0.95 with a near-grey behavior after significant thermal aggression, but depending on the materials of interest, some significant evolution may be first observed, especially during the early stages of the degradation. Supplementary inaccuracy can come from the heterogeneity of the incident flux on the slab. As a whole, discrepancies up to 20% can be observed on the absorbed flux depending on the degradation time, mainly because of the spectral variations of the absorption and up to 10% more, depending on the position on the slab. Simple models with a constant and unique value of absorptivity may then lead to inaccuracies in the evaluation of the radiative flux absorption, with possible consequences on the pyrolysis analysis, especially for properties related to the early step of the degradation process, like the time to ignition, for example.

  12. On the Influence of the Sample Absorptivity when Studying the Thermal Degradation of Materials.

    Science.gov (United States)

    Boulet, Pascal; Brissinger, Damien; Collin, Anthony; Acem, Zoubir; Parent, Gilles

    2015-08-21

    The change in absorptivity during the degradation process of materials is discussed, and its influence as one of the involved parameters in the degradation models is studied. Three materials with very different behaviors are used for the demonstration of its role: a carbon composite material, which is opaque, almost grey, a plywood slab, which is opaque and spectral-dependent and a clear PMMA slab, which is semitransparent. Data are analyzed for virgin and degraded materials at different steps of thermal degradation. It is seen that absorptivity and emissivity often reach high values in the range of 0.90-0.95 with a near-grey behavior after significant thermal aggression, but depending on the materials of interest, some significant evolution may be first observed, especially during the early stages of the degradation. Supplementary inaccuracy can come from the heterogeneity of the incident flux on the slab. As a whole, discrepancies up to 20% can be observed on the absorbed flux depending on the degradation time, mainly because of the spectral variations of the absorption and up to 10% more, depending on the position on the slab. Simple models with a constant and unique value of absorptivity may then lead to inaccuracies in the evaluation of the radiative flux absorption, with possible consequences on the pyrolysis analysis, especially for properties related to the early step of the degradation process, like the time to ignition, for example.

  13. Harvard Aging Brain Study : Dataset and accessibility

    NARCIS (Netherlands)

    Dagley, Alexander; LaPoint, Molly; Huijbers, Willem; Hedden, Trey; McLaren, Donald G.; Chatwal, Jasmeer P.; Papp, Kathryn V.; Amariglio, Rebecca E.; Blacker, Deborah; Rentz, Dorene M.; Johnson, Keith A.; Sperling, Reisa A.; Schultz, Aaron P.

    2017-01-01

    The Harvard Aging Brain Study is sharing its data with the global research community. The longitudinal dataset consists of a 284-subject cohort with the following modalities acquired: demographics, clinical assessment, comprehensive neuropsychological testing, clinical biomarkers, and neuroimaging.

  14. Degradation of aged plants by corrosion: 'Long cell action' in unresolved corrosion issues

    International Nuclear Information System (INIS)

    Saji, Genn

    2009-01-01

    In a series of previously published papers the author has identified that 'long cell action' corrosion plays a pivotal role in practically all unresolved corrosion issues for all types of nuclear power plants (e.g. PWR/VVER, BWR/RBMK and CANDU). Some of these unresolved issues are IGSCC, PWSCC, AOA and FAC (erosion-corrosion). In conventional corrosion science it is well established that 'long cell action' can seriously accelerate or suppress the local cell corrosion activities. Although long cell action is another fundamental mechanism of corrosion, especially in a 'soil corrosion' arena, potential involvement of this corrosion process has never been studied in nuclear and fossil power plants as far as the author has been able to establish. The author believes that the omission of this basic corrosion mechanism is the root cause of practically all un-resolved corrosion issues. In this paper, the author further elaborated on his assessment to other key corrosion issues, e.g. steam generator and turbine corrosion issues, while briefly summarizing previous discussions for completeness purposes, as well as introducing additional experimental and theoretical evidence of this basic corrosion mechanism. Due to the importance of this potential mechanism the author is calling for institutional review activities and further verification experiments in the form of a joint international project.

  15. Aging of nuclear station diesel generators: Evaluation of operating and expert experience: Phase 1, Study

    International Nuclear Information System (INIS)

    Hoopingarner, K.R.; Vause, J.W.; Dingee, D.A.; Nesbitt, J.F.

    1987-08-01

    Pacific Northwest Laboratory evaluated operational and expert experience pertaining to the aging degradation of diesel generators in nuclear service. The research, sponsored by the US Nuclear Regulatory Commission (NRC), identified and characterized the contribution of aging to emergency diesel generator failures. This report, Volume I, reviews diesel-generator experience to identify the systems and components most subject to aging degradation and isolates the major causes of failure that may affect future operational readiness. Evaluations show that as plants age, the percent of aging-related failures increases and failure modes change. A compilation is presented of recommended corrective actions for the failures identified. This study also includes a review of current, relevant industry programs, research, and standards. Volume II reports the results of an industry-wide workshop held on May 28 and 29, 1986 to discuss the technical issues associated with aging of nuclear service emergency diesel generators

  16. Visual degradation in Leonardo da Vinci's iconic self-portrait: A nanoscale study

    Science.gov (United States)

    Conte, A. Mosca; Pulci, O.; Misiti, M. C.; Lojewska, J.; Teodonio, L.; Violante, C.; Missori, M.

    2014-06-01

    The discoloration of ancient paper, due to the development of oxidized groups acting as chromophores in its chief component, cellulose, is responsible for severe visual degradation in ancient artifacts. By adopting a non-destructive approach based on the combination of optical reflectance measurements and time-dependent density functional theory ab-initio calculations, we describe and quantify the chromophores affecting Leonardo da Vinci's iconic self-portrait. Their relative concentrations are very similar to those measured in modern and ancient samples aged in humid environments. This analysis quantifies the present level of optical degradation of the Leonardo da Vinci's self-portrait which, compared with future measurements, will assess its degradation rate. This is a fundamental information in order to plan appropriate conservation strategies.

  17. Comparison of protein degradation, protein oxidation, and μ-calpain activation between pale, soft, and exudative and red, firm, and nonexudative pork during postmortem aging.

    Science.gov (United States)

    Yin, Y; Zhang, W G; Zhou, G H; Guo, B

    2014-08-01

    The objective of this study was to investigate the differences in protein modifications between pale, soft, and exudative (PSE) and red, firm, and nonexudative (RFN) pork during postmortem (PM) aging. Longissimus dorsi (LD) including 8 PSE and 8 RFN muscles were individually removed from 16 carcasses. These 16 LD muscles were vacuum packaged at 24 h after slaughter and stored at 4°C for 1, 3, and 5 d. The centrifugation loss, drip loss, color, protein solubility, protein oxidation, protein degradation including desmin, troponin T, and integrin, and μ-calpain activation were determined. The pH of PSE samples was significantly lower than that of RFN samples at both 1 and 24 h PM (P 0.05). In addition, PSE pork presented a lower solubility of sarcoplasmic protein, myofibrillar protein, and total protein than RFN pork except the solubility of myofibrillar protein at d 1 (P firm, and nonexudative pork presented lower intensity of intact 80 kDa calpain and greater intensity of autolyzed 76 kDa product compared to PSE pork (P < 0.01). The results indicate that the degree of μ-calpain activation, the extent of protein degradation including desmin and integrin, and the level of protein solubility in PSE pork could contribute to its low water holding capacity during PM storage.

  18. Preliminary degradation process study of infectious biological waste in a 5 k W thermal plasma equipment

    International Nuclear Information System (INIS)

    Xochihua S M, M.C.

    1997-01-01

    This work is a preliminary study of infectious biological waste degradation process by thermal plasma and was made in Thermal Plasma Applications Laboratory of Environmental Studies Department of the National Institute of Nuclear Research (ININ). Infectious biological waste degradation process is realized by using samples such polyethylene, cotton, glass, etc., but the present study scope is to analyze polyethylene degradation process with mass and energy balances involved. Degradation method is realized as follow: a polyethylene sample is put in an appropriated crucible localized inside a pyrolysis reactor chamber, the plasma jet is projected to the sample, by the pyrolysis phenomena the sample is degraded into its constitutive particles: carbon and hydrogen. Air was utilized as a recombination gas in order to obtain the higher percent of CO 2 if amount of O 2 is greater in the recombination gas, the CO generation is reduced. The effluent gases of exhaust pyrolysis reactor through are passed through a heat exchanger to get cooled gases, the temperature water used is 15 Centigrade degrees. Finally the gases was tried into absorption tower with water as an absorbent fluid. Thermal plasma degradation process is a very promising technology, but is necessary to develop engineering process area to avail all advantages of thermal plasma. (Author)

  19. Effects of prior information on decoding degraded speech: an fMRI study.

    Science.gov (United States)

    Clos, Mareike; Langner, Robert; Meyer, Martin; Oechslin, Mathias S; Zilles, Karl; Eickhoff, Simon B

    2014-01-01

    Expectations and prior knowledge are thought to support the perceptual analysis of incoming sensory stimuli, as proposed by the predictive-coding framework. The current fMRI study investigated the effect of prior information on brain activity during the decoding of degraded speech stimuli. When prior information enabled the comprehension of the degraded sentences, the left middle temporal gyrus and the left angular gyrus were activated, highlighting a role of these areas in meaning extraction. In contrast, the activation of the left inferior frontal gyrus (area 44/45) appeared to reflect the search for meaningful information in degraded speech material that could not be decoded because of mismatches with the prior information. Our results show that degraded sentences evoke instantaneously different percepts and activation patterns depending on the type of prior information, in line with prediction-based accounts of perception. Copyright © 2012 Wiley Periodicals, Inc.

  20. A study of poly(vinyl alcohol thermal degradation by thermogravimetry and differential thermogravimetry

    Directory of Open Access Journals (Sweden)

    Julián Esteban Barrera

    2007-05-01

    Full Text Available The thermal degradation of poly(vinyl alcohol (PVA having different degrees of hydrolysis and molecular weights was studied by thermogravimetry (TGA and differential thermogravimetry (DTGA. Four degradation events were identified whose intensity was related to the degree of hydrolysis. It was verified that the solid-state degradation mechanism for high hydrolysis degrees corresponded to eliminating water-forming side groups in stoichiometric amounts. The presence of acetate groups and lower melting points delayed the polymer’s thermal decomposition at lower hydrolysis degrees. There was no direct correlation in these samples between weight-loss during the first degradation event and the stoichiometric quantities which would be produced by eliminating the side groups. Reaction order and energy activation value qualitative coincidence was found by evaluating experimental data by using Freeman-Carroll and Friedman kinetic models.

  1. Kinetic study on the photocatalytic degradation of salicylic acid using ZnO catalyst

    International Nuclear Information System (INIS)

    Nageswara Rao, A.; Sivasankar, B.; Sadasivam, V.

    2009-01-01

    The photocatalytic degradation of salicylic acid was studied by a batch process using ZnO as the catalyst on irradiation with UV light. The effect of process parameters such as pH, catalyst loading and initial concentration of salicylic acid on the extent of degradation was investigated. The degradation of salicylic acid was found to be effective in the neutral pH range. The optimum catalyst loading was observed at 2.0 g/L. The process followed first order kinetics and the apparent rate constant decreased with increase in the initial concentration of salicylic acid. The mechanism for the degradation of salicylic acid could be explained on the basis of Langmuir-Hinshelwood mechanism. The complete mineralization of salicylic acid was observed in the presence of ZnO photocatalyst. The ZnO was found to be quite stable and undergoes photocorrosion only to a negligible extent.

  2. Study on degrading graphene oxide in wastewater under different conditions for developing an efficient and economical degradation method.

    Science.gov (United States)

    Li, Ting; Zhang, Chao-Zhi; Gu, Chengyue

    2017-12-01

    With popular application of graphene and graphene oxide (GO), they have been discharged into water. Graphene and GO harm organisms. However, an efficient and economical method for removing graphene and GO in wastewater has seldom been reported. Graphene can be oxidized by hydrogen peroxide to give GO; therefore, degradation of graphene oxide is an important step in the procedure of removal of graphene from water. In this paper, GO degradation via photo-Fenton reaction under different conditions was carried out. Experimental results suggested that GO in wastewater can be efficiently and economically degraded into carbon dioxide and H 2 O when pH value is 3, concentration of H 2 O 2 and FeCl 3 are 35 mM and 5 ppm, respectively. Degradation mechanism of GO was suggested based on UV-vis absorption spectra, scanning electron microscopy, X-ray diffraction and liquid chromatography-mass spectra data of degradation intermediates. This paper suggests an efficient and economical degradation way of GO in wastewater.

  3. Study on FPGA-Based Emulator for the Diagnosis of Gradual Degradation in Reciprocating Pump

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang Sun; Kim, Wooshik [Sejong Univ., Seoul (Korea, Republic of); Kim, Tae Yun; Chai, Jang Bom [Ajou Univ., Suwon (Korea, Republic of)

    2017-01-15

    The purpose of this study is to develop a method for diagnosing the degree of gradual degradation of a reciprocating pump caused by continuous use as a water supply pump in a nuclear power plant. Normally, the progress of such degradation is too slow to be noticed. Hence, it is difficult to determine the degree of degradation using the existing diagnostic methods. In this paper, we propose a new method by which the normal state and the degraded state of the pump can be differentiated, so that the degree of degradation can be identified. First, an emulator was developed using FPGA by providing the parameters of the pump under normal state, so that the emulator generates the information of the pump in the healthy state. Then, by comparing this information with the parameters received from various output sensors of the emulator during the current state, it is possible to identify and measure the degree of gradual degradation. This paper presents some of the results obtained during the development process, and results that show how the emulator operates, by comparing the data collected from an actual pump.

  4. Die degradation effect on aging rate in accelerated cycling tests of SiC power MOSFET modules

    DEFF Research Database (Denmark)

    Luo, Haoze; Baker, Nick; Iannuzzo, Francesco

    2017-01-01

    In order to distinguish the die and bond wire degradations, in this paper both the die and bond wire resistances of SiC MOSFET modules are measured and tested during the accelerated cycling tests. It is proved that, since the die degradation under specific conditions increases the temperature swing...

  5. Degradation Studies of β-Cyclodextrin Polyurethane Polymers using

    African Journals Online (AJOL)

    diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) were carried out by exposing the polymers to different soil types for up to 120 days. The aim of the study was to determine the fate of these novel polymers in the environment.

  6. A study on the evaluation of material degradation using ball indentation method

    International Nuclear Information System (INIS)

    Kim, Jeong Pyo; Seok, Chang Sung; Ahn, Ha Neul

    2000-01-01

    As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the aging evaluation technique by the BI method. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree

  7. In vivo study of magnesium plate and screw degradation and bone fracture healing.

    Science.gov (United States)

    Chaya, Amy; Yoshizawa, Sayuri; Verdelis, Kostas; Myers, Nicole; Costello, Bernard J; Chou, Da-Tren; Pal, Siladitya; Maiti, Spandan; Kumta, Prashant N; Sfeir, Charles

    2015-05-01

    Each year, millions of Americans suffer bone fractures, often requiring internal fixation. Current devices, like plates and screws, are made with permanent metals or resorbable polymers. Permanent metals provide strength and biocompatibility, but cause long-term complications and may require removal. Resorbable polymers reduce long-term complications, but are unsuitable for many load-bearing applications. To mitigate complications, degradable magnesium (Mg) alloys are being developed for craniofacial and orthopedic applications. Their combination of strength and degradation make them ideal for bone fixation. Previously, we conducted a pilot study comparing Mg and titanium devices with a rabbit ulna fracture model. We observed Mg device degradation, with uninhibited healing. Interestingly, we observed bone formation around degrading Mg, but not titanium, devices. These results highlighted the potential for these fixation devices. To better assess their efficacy, we conducted a more thorough study assessing 99.9% Mg devices in a similar rabbit ulna fracture model. Device degradation, fracture healing, and bone formation were evaluated using microcomputed tomography, histology and biomechanical tests. We observed device degradation throughout, and calculated a corrosion rate of 0.40±0.04mm/year after 8 weeks. In addition, we observed fracture healing by 8 weeks, and maturation after 16 weeks. In accordance with our pilot study, we observed bone formation surrounding Mg devices, with complete overgrowth by 16 weeks. Bend tests revealed no difference in flexural load of healed ulnae with Mg devices compared to intact ulnae. These data suggest that Mg devices provide stabilization to facilitate healing, while degrading and stimulating new bone formation. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Degradation study of pesticides by direct photolysis - Structural characterization and potential toxicity of photo products

    International Nuclear Information System (INIS)

    Rifai, A.

    2013-01-01

    Pesticides belong to the large family of organic pollutants. In general, they are intended to fight against crop pests. Distribution of pesticides in nature creates pollution in DIFFERENT compartments of the biosphere (water, soil and air) and can induce acute toxic effects on human beings of the terrestrial and aquatic living biomass. It is now shown that some pesticides are endocrine disruptors and are particularly carcinogenic and mutagenic effects in humans. Pesticides can undergo various processes of transformation in the natural life cycle (biodegradation, volatilization, solar radiation ...) or following applied in the sectors of natural water purification and treatment stations sewage treatment. The presence of degradation products of pesticides in our environment is even more alarming that their structures and potential toxicities generally unknown. Molecules belonging to two families of pesticides were selected for this study: herbicides, represented by metolachlor, and fungicides represented by procymidone, pyrimethanil and boscalid. The first part of the thesis focused on the development of an analytical strategy to characterize the structures of compounds from degradation by photolysis of pesticides. The second part focused on estimating the toxicity of degradation products using a test database in silico. Identification of degradation products was achieved through two complementary analysis techniques: the gas chromatography coupled to a mass spectrometer ''multi-stage'' (GC-MSn) and liquid chromatography coupled to a tandem mass spectrometer (LC-MS/MS). The estimation of the toxicity of the degradation products was performed using the TEST program QSAR recently developed to try to predict the toxicity of molecules. The strategy of the structural elucidation of degradation products of pesticides studied is based on studying of the mechanisms of fragmentation of parent molecules of the degradation products. The molar mass of parent

  9. Studies on hydrocarbon degradation by the bacterial isolate ...

    African Journals Online (AJOL)

    The hydrocarbon utilizing capability of Stenotrophomonas rhizophila (PM-1), isolated from oil contaminated soil composts from Western Ghats region of Karnataka was analyzed. In the bioremediation experiment, ONGC heavy crude oil and poly aromatic hydrocarbons (PAHs) utilization by the bacterial isolate was studied.

  10. Variability in microbiological degradation experiments, analysis and case study

    DEFF Research Database (Denmark)

    Sommer, Helle Mølgaard

    1997-01-01

    and describes analysis techniques for testing the reproducibility of a given experiment. The parameter estimation method employed for the experiments in this study is based on an iterative maximum likelihood method and the test statistic is an approximated likelihood ratio test. The estimations were carried out...

  11. Benzene degradation coupled with chlorate reduction in soil column study

    NARCIS (Netherlands)

    Tan, N.C.G.; Doesburg, van W.C.J.; Langenhoff, A.A.M.; Stams, A.J.M.

    2006-01-01

    Perchlorate and chlorate are electron acceptors that during reduction result in the formation of molecular oxygen. The produced oxygen can be used for activation of anaerobic persistent pollutants, like benzene. In this study chlorate was tested as potential electron acceptor to stimulate benzene

  12. Photo-stability study of a solution-processed small molecule solar cell system: correlation between molecular conformation and degradation.

    Science.gov (United States)

    Newman, Michael J; Speller, Emily M; Barbé, Jérémy; Luke, Joel; Li, Meng; Li, Zhe; Wang, Zhao-Kui; Jain, Sagar M; Kim, Ji-Seon; Lee, Harrison Ka Hin; Tsoi, Wing Chung

    2018-01-01

    Solution-processed organic small molecule solar cells (SMSCs) have achieved efficiency over 11%. However, very few studies have focused on their stability under illumination and the origin of the degradation during the so-called burn-in period. Here, we studied the burn-in period of a solution-processed SMSC using benzodithiophene terthiophene rhodamine:[6,6]-phenyl C 71 butyric acid methyl ester (BTR:PC 71 BM) with increasing solvent vapour annealing time applied to the active layer, controlling the crystallisation of the BTR phase. We find that the burn-in behaviour is strongly correlated to the crystallinity of BTR. To look at the possible degradation mechanisms, we studied the fresh and photo-aged blend films with grazing incidence X-ray diffraction, UV-vis absorbance, Raman spectroscopy and photoluminescence (PL) spectroscopy. Although the crystallinity of BTR affects the performance drop during the burn-in period, the degradation is found not to originate from the crystallinity changes of the BTR phase, but correlates with changes in molecular conformation - rotation of the thiophene side chains, as resolved by Raman spectroscopy which could be correlated to slight photobleaching and changes in PL spectra.

  13. Organic tanks safety program FY95 waste aging studies

    International Nuclear Information System (INIS)

    Camaioni, D.M.; Samuels, W.D.; Clauss, S.A.; Lenihan, B.D.; Wahl, K.L.; Campbell, J.A.; Shaw, W.J.

    1995-09-01

    This report gives the second year's findings of a study of how thermal and radiological processes may change the composition of organic compounds in the underground tanks at Hanford. Efforts were focused on the global reaction kinetics in a simulated waste exposed to γ rays and the reactions of organic radicals with nitrite ion. The gas production is predominantly radiolytic. Decarboxylation of carboxylates is probably an aging pathway. TBP was totaly consumed in almost every run. Radiation clearly accelerated consumption of the other compounds. EDTA is more reactive than citrate. Oximes and possibly organic nitro compounds are key intermediates in the radiolytic redox reactions of organic compounds with nitrate/nitrite. Observations are consistent with organic compounds being progressively degraded to compounds with greater numbers of C-O bonds and fewer C-H and C-C bonds, resulting in an overall lower energy content. If the radwaste tanks are adequately ventilated and continually dosed by radioactivity, their total energy content should have declined. Level of risk depends on how rapidly carboxylate salts of moderate energy content (including EDTA fragments) degrade to low energy oxalate and formate

  14. Contribution to the study of the degradation of the solvent used in a nuclear fuel reprocessing plant

    International Nuclear Information System (INIS)

    Goasmat, F.

    1984-01-01

    The degradation of a mixed solvent (tributylphosphate - hydrocarbons) in a fuel reprocessing plant (UP 2 at La Hague, France) is studied in this thesis. Laboratory studies on degradation mechanisms, decomposition products and regeneration processes are reviewed in a bibliographic synthesis. Solvent degradation is investigated on a real solvent from a reprocessing plant. Influence of degradation on solvent performance is shown and regeneration processes should be improved. Many regeneration processes are tested on solvent from the plant and results are discussed. Separation and analysis of degradation products show the polyfunctional structure of compounds formed [fr

  15. Age 60 Study. Part 1. Bibliographic Database

    Science.gov (United States)

    1994-10-01

    CMIATIONS phanocardlography, study of the arterial distensibility by the carotidogm, and the chronocudiographic meuurement of an index of systolic flow and...pilot performance and age, considering muscular strength, cardio-respiratory capacity, body weight and mental aspects). AEROSPACE MEDICINE, VOL. 42...great differences exhibited in the dynamic muscular endurance, aerobic capacity, power, agility, and coordination for the two groups. The standard

  16. 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.

  17. 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.

  18. Atmospheric degradation of 3-methylfuran: kinetic and products study

    Directory of Open Access Journals (Sweden)

    A. Tapia

    2011-04-01

    Full Text Available A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases, using a relative method with different experimental techniques. The rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1 kOH = (1.13 ± 0.22 × 10−10 and kNO3 = (1.26 ± 0.18 × 10−11. Products from the reaction of 3-methylfuran with OH, NO3 and Cl atoms in the absence and in the presence of NO have also been determined. The main reaction products obtained were chlorinated methylfuranones and hydroxy-methylfuranones in the reaction of 3-methylfuran with Cl atoms, 2-methylbutenedial, 3-methyl-2,5-furanodione and hydroxy-methylfuranones in the reaction of 3-methylfuran with OH and NO3 radicals and also nitrated compounds in the reaction with NO3 radicals. The results indicate that, in all cases, the main reaction path is the addition to the double bond of the aromatic ring followed by ring opening in the case of OH and NO3 radicals. The formation of 3-furaldehyde and hydroxy-methylfuranones (in the reactions of 3-methylfuran with Cl atoms and NO3 radicals confirmed the H-atom abstraction from the methyl group and from the aromatic ring, respectively. This study represents the first product determination for Cl atoms and NO3 radicals in reactions with 3-methylfuran. The reaction mechanisms and atmospheric implications of the reactions under consideration are also discussed.

  19. A Critical Appraisal of Quantitative Studies of Protein Degradation in the Framework of Cellular Proteostasis

    Directory of Open Access Journals (Sweden)

    Beatriz Alvarez-Castelao

    2012-01-01

    Full Text Available Protein homeostasis, proteostasis, is essential to understand cell function. Protein degradation is a crucial component of the proteostatic mechanisms of the cell. Experiments on protein degradation are nowadays present in many investigations in the field of molecular and cell biology. In the present paper, we focus on the different experimental approaches to study protein degradation and present a critical appraisal of the results derived from steady-state and kinetic experiments using detection of unlabelled and labelled protein methodologies with a proteostatic perspective. This perspective allows pinpointing the limitations in interpretation of results and the need of further experiments and/or controls to establish “definitive evidence” for the role of protein degradation in the proteostasis of a given protein or the entire proteome. We also provide a spreadsheet for simple calculations of mRNA and protein decays for mimicking different experimental conditions and a checklist for the analysis of experiments dealing with protein degradation studies that may be useful for researchers interested in the area of protein turnover.

  20. Comparison study of different coatings on degradation performance and cell response of Mg-Sr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shangguan, Yongming [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Sun, Lina [Jinzhou Medical University, Jinzhou 121000 (China); Wan, Peng, E-mail: pwan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Tan, Lili [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Wang, Chengyue [Jinzhou Medical University, Jinzhou 121000 (China); Fan, Xinmin [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Qin, Ling [Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-12-01

    To solve the problem of rapid degradation for magnesium-based implants, surface modification especially coating method is widely studied and showed the great potential for clinical application. However, as concerned to the further application and medical translation for biodegradable magnesium alloys, there are still lack of data and comparisons among different coatings on their degradation and biological properties. This work studied three commonly used coatings on Mg-Sr alloy, including micro-arc oxidation coating, electrodeposition coating and chemical conversion coating, and compared these coatings for requirements of favorable degradation and biological performances, how each of these coating systems has performed. Finally the mechanism for the discrepancy between these coatings is proposed. The results indicate that the micro-arc oxidation coating on Mg-Sr alloy exhibited the best corrosion resistance and cell response among these coatings, and is proved to be more suitable for the orthopedic application. - Highlights: • The MAO, PED and Sr-P coating were fabricated on Mg-Sr alloy to evaluate the degradation. • The MAO coating showed the greatest degradation performance among these three coatings. • The PED coating exhibited worse corrosion resistance even than Mg-Sr substrate. • The value of cell proliferation and ALP activity were ranked in the following order: MAO > Sr-P > PED.

  1. Comparison study of different coatings on degradation performance and cell response of Mg-Sr alloy

    International Nuclear Information System (INIS)

    Shangguan, Yongming; Sun, Lina; Wan, Peng; Tan, Lili; Wang, Chengyue; Fan, Xinmin; Qin, Ling; Yang, Ke

    2016-01-01

    To solve the problem of rapid degradation for magnesium-based implants, surface modification especially coating method is widely studied and showed the great potential for clinical application. However, as concerned to the further application and medical translation for biodegradable magnesium alloys, there are still lack of data and comparisons among different coatings on their degradation and biological properties. This work studied three commonly used coatings on Mg-Sr alloy, including micro-arc oxidation coating, electrodeposition coating and chemical conversion coating, and compared these coatings for requirements of favorable degradation and biological performances, how each of these coating systems has performed. Finally the mechanism for the discrepancy between these coatings is proposed. The results indicate that the micro-arc oxidation coating on Mg-Sr alloy exhibited the best corrosion resistance and cell response among these coatings, and is proved to be more suitable for the orthopedic application. - Highlights: • The MAO, PED and Sr-P coating were fabricated on Mg-Sr alloy to evaluate the degradation. • The MAO coating showed the greatest degradation performance among these three coatings. • The PED coating exhibited worse corrosion resistance even than Mg-Sr substrate. • The value of cell proliferation and ALP activity were ranked in the following order: MAO > Sr-P > PED.

  2. The Impact of Charcoal Production on Forest Degradation: a Case Study in Tete, Mozambique

    Science.gov (United States)

    Sedano, F.; Silva. J. A.; Machoco, R.; Meque, C. H.; Sitoe, A.; Ribeiro, N.; Anderson, K.; Ombe, Z. A.; Baule, S. H.; Tucker, C. J.

    2016-01-01

    Charcoal production for urban energy consumption is a main driver of forest degradation in sub-Saharan Africa. Urban growth projections for the continent suggest that the relevance of this process will increase in the coming decades. Forest degradation associated to charcoal production is difficult to monitor and commonly overlooked and underrepresented in forest cover change and carbon emission estimates. We use a multi-temporal dataset of very high-resolution remote sensing images to map kiln locations in a representative study area of tropical woodlands in central Mozambique. The resulting maps provided a characterization of the spatial extent and temporal dynamics of charcoal production. Using an indirect approach we combine kiln maps and field information on charcoal making to describe the magnitude and intensity of forest degradation linked to charcoal production, including aboveground biomass and carbon emissions. Our findings reveal that forest degradation associated to charcoal production in the study area is largely independent from deforestation driven by agricultural expansion and that its impact on forest cover change is in the same order of magnitude as deforestation. Our work illustrates the feasibility of using estimates of urban charcoal consumption to establish a link between urban energy demands and forest degradation. This kind of approach has potential to reduce uncertainties in forest cover change and carbon emission assessments in sub-Saharan Africa.

  3. Mechanical degradation of Emplacement Drifts at Yucca Mountain - A Modeling Case Study. Part I: Nonlithophysal Rock

    International Nuclear Information System (INIS)

    M. Lin; D. Kicker; B. Damjanac; M. Board; M. Karakouzian

    2006-01-01

    This paper outlines rock mechanics investigations associated with mechanical degradation of planned emplacement drifts at Yucca Mountain, which is the designated site for the proposed U.S. high-level nuclear waste repository. The factors leading to drift degradation include stresses from the overburden, stresses induced by the heat released from the emplaced waste, stresses due to seismically related ground motions, and time-dependent strength degradation. The welded tuff emplacement horizon consists of two groups of rock with distinct engineering properties: nonlithophysal units and lithophysal units, based on the relative proportion of lithophysal cavities. The term 'lithophysal' refers to hollow, bubble like cavities in volcanic rock that are surrounded by a porous rim formed by fine-grained alkali feldspar, quartz, and other minerals. Lithophysae are typically a few centimeters to a few decimeters in diameter. Part I of the paper concentrates on the generally hard, strong, and fractured nonlithophysal rock. The degradation behavior of the tunnels in the nonlithophysal rock is controlled by the occurrence of keyblocks. A statistically equivalent fracture model was generated based on extensive underground fracture mapping data from the Exploratory Studies Facility at Yucca Mountain. Three-dimensional distinct block analyses, generated with the fracture patterns randomly selected from the fracture model, were developed with the consideration of in situ, thermal, and seismic loads. In this study, field data, laboratory data, and numerical analyses are well integrated to provide a solution for the unique problem of modeling drift degradation

  4. Study of the degradation of liquid-organic radioactive wastes by electrochemical methods

    International Nuclear Information System (INIS)

    Hernandez A, J. I.

    2015-01-01

    In this study degradation studies were performed on blank samples, in which two electrochemical cells with different electrodes were used, the first is constituted by mesh electrodes Ti/Ir-Ta/Ti and the second by rod electrodes Ti/Ddb, using as reference an electrolytic medium of scintillation liquid and scintillation liquid more water, applying different potentials ranging from 1 to 25 V. After obtaining the benchmarks, the treatment was applied to samples containing organic liquid radioactive waste, in this case a short half-life radioisotope as Sulfur-35, the degradation characterization of organic compounds was performed in infrared spectrometry. (Author)

  5. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    Energy Technology Data Exchange (ETDEWEB)

    Bellocco, E. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy)], E-mail: bellocco@isengard.unime.it; Barreca, D.; Lagana, G.; Leuzzi, U. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy); Migliardo, F.; Torre, R. La; Galli, G. [Department of Physics, University of Messina, Messina (Italy); Galtieri, A. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy); Minutoli, L.; Squadrito, F. [Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Messina (Italy)

    2008-04-18

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t{sub 1/2} (half life time), as determined by high performance liquid chromatography (HPLC)

  6. A thin film degradation study of a fluorinated polyether liquid lubricant using an HPLC method

    Science.gov (United States)

    Morales, W.

    1986-01-01

    A High Pressure Liquid Chromatography (HPLC) separation method was developed to study and analyze a fluorinated polyether fluid which is promising liquid lubricant for future applications. This HPLC separation method was used in a preliminary study investigating the catalytic effect of various metal, metal alloy, and ceramic engineering materials on the degradation of this fluid in a dry air atmosphere at 345 C. Using a 440 C stainless steel as a reference catalytic material it was found that a titanium alloy and a chromium plated material degraded the fluorinated polyether fluid substantially more than the reference material.

  7. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    International Nuclear Information System (INIS)

    Bellocco, E.; Barreca, D.; Lagana, G.; Leuzzi, U.; Migliardo, F.; Torre, R. La; Galli, G.; Galtieri, A.; Minutoli, L.; Squadrito, F.

    2008-01-01

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t 1/2 (half life time), as determined by high performance liquid chromatography (HPLC)

  8. A compact multi-chamber setup for degradation and lifetime studies of organic solar cells

    DEFF Research Database (Denmark)

    Gevorgyan, Suren; Jørgensen, Mikkel; Krebs, Frederik C

    2011-01-01

    A controlled atmosphere setup designed for long-term degradation studies of organic solar cells under illumination is presented. The setup was designed with ease-of-use and compactness in mind and allows for multiple solar cells distributed on four glass substrates to be studied in four different...

  9. Forced degradation studies of lansoprazole using LC-ESI HRMS and 1 H-NMR experiments: in vitro toxicity evaluation of major degradation products.

    Science.gov (United States)

    Shankar, G; Borkar, R M; Suresh, U; Guntuku, L; Naidu, V G M; Nagesh, N; Srinivas, R

    2017-07-01

    Regulatory agencies from all over the world have set up stringent guidelines with regard to drug degradation products due to their toxic effects or carcinogenicity. Lansoprazole, a proton-pump inhibitor, was subjected to forced degradation studies as per ICH guidelines Q1A (R2). The drug was found to degrade under acidic, basic, neutral hydrolysis and oxidative stress conditions, whereas it was found to be stable under thermal and photolytic conditions. The chromatographic separation of the drug and its degradation products were achieved on a Hiber Purospher, C18 (250 × 4.6 mm, 5 μ) column using 10 mM ammonium acetate and acetonitrile as a mobile phase in a gradient elution mode at a flow rate of 1.0 ml/min. The eight degradation products (DP1-8) were identified and characterized by UPLC/ESI/HRMS with in-source CID experiments combined with accurate mass measurements. DP-1, DP-2 and DP-3 were formed in acidic, DP-4 in basic, DP-5 in neutral and DP-1, DP-6, DP-7 and DP-8 were in oxidation stress condition Among eight degradation products, five were hitherto unknown degradation products. In addition, one of the major degradation products, DP-2, was isolated by using semi preparative HPLC and other two, DP-6 and DP-7 were synthesized. The cytotoxic effect of these degradation products (DP-2, DP-6 and DP-7) were tested on normal human cells such as HEK 293 (embryonic kidney cells) and RWPE-1(normal prostate epithelial cells) by MTT assay. From the results of cytotoxicity, it was found that lansoprazole as well as its degradation products (DP-2, DP-6 and DP-7) were nontoxic up to 50-μM concentrations, and the latter showed slightly higher cytotoxicity when compared with that of lansoprazole. DNA binding studies using spectroscopic techniques indicate that DP-2, DP-6 and DP-7 molecules interact with ctDNA and may bind to its surface. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  10. [Studies on photo-electron-chemical catalytic degradation of the malachite green].

    Science.gov (United States)

    Li, Ming-yu; Diao, Zeng-hui; Song, Lin; Wang, Xin-le; Zhang, Yuan-ming

    2010-07-01

    A novel two-compartment photo-electro-chemical catalytic reactor was designed. The TiO2/Ti thin film electrode thermally formed was used as photo-anode, and graphite as cathode and a saturated calomel electrode (SCE) as the reference electrode in the reactor. The anode compartment and cathode compartment were connected with the ionic exchange membrane in this reactor. Effects of initial pH, initial concentration of malachite green and connective modes between the anode compartment and cathode compartment on the decolorization efficiency of malachite green were investigated. The degradation dynamics of malachite green was studied. Based on the change of UV-visible light spectrum, the degradation process of malachite green was discussed. The experimental results showed that, during the time of 120 min, the decolouring ratio of the malachite green was 97.7% when initial concentration of malachite green is 30 mg x L(-1) and initial pH is 3.0. The catalytic degradation of malachite green was a pseudo-first order reaction. In the degradation process of malachite green the azo bond cleavage and the conjugated system of malachite green were attacked by hydroxyl radical. Simultaneity, the aromatic ring was oxidized. Finally, malachite green was degraded into other small molecular compounds.

  11. A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition.

    Science.gov (United States)

    Souri, E; Aghdami, A Negahban; Adib, N

    2014-01-01

    An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r(2)>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms.

  12. Building and commissioning of a setup to study ageing phenomena in gaseous detectors

    International Nuclear Information System (INIS)

    Abuhoza, A.; Schmidt, H.R.; Biswas, S.; Frankenfeld, U.; Hehner, J.; Schmidt, C.J.

    2016-01-01

    In high-rate heavy-ion experiments, gaseous detectors encounter big challenges in terms of degradation of their performance due to a phenomenon called ageing. A setup for high precision ageing studies has been constructed and commissioned at the GSI detector laboratory. The setup as well as the gas system have been carefully optimized to reach a high sensitivity for ageing effects. Two different materials have been examined for their influence on gaseous detectors: RTV-3145 and Gerband 705. The details of the construction of the ageing test setup and the test results will be presented.

  13. Building and commissioning of a setup to study ageing phenomena in gaseous detectors

    Energy Technology Data Exchange (ETDEWEB)

    Abuhoza, A., E-mail: aabuhoza@kacst.edu.sa [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 64291 (Germany); King Abdulaziz City for Science and Technology (KACST), Riyadh (Saudi Arabia); Goethe-Universität, Frankfurt (Germany); Schmidt, H.R. [Eberhard-Karls-Universität, Tübingen (Germany); Biswas, S. [School of Physical Sciences, National Institute of Science Education and Research, Jatni 752050 (India); Frankenfeld, U.; Hehner, J.; Schmidt, C.J. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 64291 (Germany)

    2016-07-11

    In high-rate heavy-ion experiments, gaseous detectors encounter big challenges in terms of degradation of their performance due to a phenomenon called ageing. A setup for high precision ageing studies has been constructed and commissioned at the GSI detector laboratory. The setup as well as the gas system have been carefully optimized to reach a high sensitivity for ageing effects. Two different materials have been examined for their influence on gaseous detectors: RTV-3145 and Gerband 705. The details of the construction of the ageing test setup and the test results will be presented.

  14. Microstructural studies on degradation of interface between LSM–YSZ cathode and YSZ electrolyte in SOFCs

    DEFF Research Database (Denmark)

    Liu, Yi-Lin; Hagen, Anke; Barfod, Rasmus

    2009-01-01

    The changes in the cathode/electrolyte interface microstructure have been studied on anode-supported technological solid oxide fuel cells (SOFCs) that were subjected to long-term (1500 h) testing at 750 °C under high electrical loading (a current density of 0.75 A/cm2). These cells exhibit...... different cathode degradation rates depending on, among others, the composition of the cathode gas, being significantly smaller in oxygen than in air. FE-SEM and high resolution analytical TEM were applied for characterization of the interface on a submicron- and nano-scale. The interface degradation has...... to decrease further due to the more pronounced formation of insulating zirconate phases that are present locally and preferably in LSM/YSZ electrolyte contact areas. The effects of the cathode gas on the interface degradation are discussed considering the change of oxygen activity at the interface, possible...

  15. Study of silica coatings degradation under laser irradiation and in controlled environment

    International Nuclear Information System (INIS)

    Becker, S.

    2006-11-01

    Performances of optical components submitted to high laser intensities are usually determined by their laser-induced damage threshold. This value represents the highest density of energy (fluence) sustainable by the component before its damage. When submitted to laser fluences far below this threshold, optical performances may also decrease with time. The degradation processes depend on laser characteristics, optical materials, and environment around the component. Silica being the most used material in optics, the aim of this study was to describe and analyse the physical-chemical mechanisms responsible for laser-induced degradation of silica coatings in controlled environment. Experimental results show that degradation is due to the growth of a carbon deposit in the irradiated zone. From these results, a phenomenological model has been proposed and validated with numerical simulations. Then, several technological solutions have been tested in order to reduce the laser-induced contamination of silica coatings. (author)

  16. A kinetic study of textile dyeing wastewater degradation by Penicillium chrysogenum.

    Science.gov (United States)

    Durruty, Ignacio; Fasce, Diana; González, Jorge Froilán; Wolski, Erika Alejandra

    2015-06-01

    The potential of Penicillium chrysogenum to decolorize azo dyes and a real industrial textile wastewater was studied. P. chrysogenum was able to decolorize and degrade three azo dyes (200 mg L(-1)), either independently or in a mixture of them, using glucose as a carbon source. A kinetic model for degradation was developed and it allowed predicting the degradation kinetics of the mixture of the three azo dyes. In addition, P. chrysogenum was able to decolorize real industrial wastewater. The kinetic model proposed was also able to predict the decolorization of the real wastewater. The calibration of the proposed model makes it a useful tool for future wastewater facilities' design and for practical applications.

  17. Study of the effect of the fibre mass UP2 degradation products on radionuclide mobilisation

    Energy Technology Data Exchange (ETDEWEB)

    Duro, Lara; Grive, Mireia; Gaona, Xavier; Bruno, Jordi [Amphos 21 Consulting S.L., Barcelona (Spain); Andersson, Thomas; Boren, Hans; Dario, Maarten [Linkoeping Univ., Linkoeping (Sweden); Allard, Bert; Hagberg, Jessica [Oerebro Univ., Oerebro (Sweden); Kaellstroem, Klas [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2012-09-15

    This report presents a literature review and laboratory work of the degradation of the fibre UP2, as well as an assessment of the effects of its degradation products on Europium sorption onto cement, as an example of their effects on radionuclide migration. All laboratory work was performed by the Swedish groups (Linkoeping and Oerebro Universities), who also performed some of the literature review. The data interpretation was performed by the Spanish team (Amphos 21). SKB has combined the reports of these studies into this common document and has added minor editorial changes. All these changes have been accepted by the authors.

  18. STUDY OF DEGRADATION MECHANISM AND PACKAGING OF ORGANIC LIGHT EMITTING DEVICES

    Institute of Scientific and Technical Information of China (English)

    Gu Xu

    2003-01-01

    Organic Light Emitting Devices (OLED) have attracted much attention recently, for their applications in future Flat Panel Displays and lighting products. However, their fast degradation remained a major obstacle to their commercialization. Here we present a brief summary of our studies on both extrinsic and intrinsic causes for the fast degradation of OLEDs. In particular, we focus on the origin of the dark spots by "rebuilding" cathodes, which confirms that the growth of dark spots occurs primarily due to cathode delamination. In the meantime, we recapture the findings from the search for suitable OLED packaging materials, in particular polymer composites, which provide both heat dissipation and moisture resistance, in addition to electrical insulation.

  19. Identifiability study of the proteins degradation model, based on ADM1, using simultaneous batch experiments

    DEFF Research Database (Denmark)

    Flotats, X.; Palatsi, J.; Ahring, Birgitte Kiær

    2006-01-01

    are not inhibiting the hydrolysis process. The ADM1 model adequately expressed the consecutive steps of hydrolysis and acidogenesis, with estimated kinetic values corresponding to a fast acidogenesis and slower hydrolysis. The hydrolysis was found to be the rate limiting step of anaerobic degradation. Estimation...... of yield coefficients based on the relative initial slopes of VFA profiles obtained in a simple batch experiment produced satisfactory results. From the identification study, it was concluded that it is possible to determine univocally the related kinetic parameter values for protein degradation...... if the evolution of amino acids is measured in simultaneous batch experiments, with different initial protein and amino acids concentrations....

  20. Parallelized system for biopolymer degradation studies through automated microresonator measurement in liquid flow

    DEFF Research Database (Denmark)

    Casci Ceccacci, Andrea; Morelli, Lidia; Bosco, Filippo

    2015-01-01

    setup unit, the system allows high-throughput measurements of resonance frequency over microresonator arrays under controlled flow conditions. We here demonstrate the acquisition of statistical data on biopolymer films degradation under enzymatic reaction over a large sample of micromechanical......In this work we present a novel automated system which allows the study of enzymatic degradation of biopolymer films coated on micromechanical resonators. The system combines an optical readout based on Blu-Ray technology with a software-controlled scanning mechanism. Integrated with a microfluidic...

  1. Study of the effect of the fibre mass UP2 degradation products on radionuclide mobilisation

    International Nuclear Information System (INIS)

    Duro, Lara; Grive, Mireia; Gaona, Xavier; Bruno, Jordi; Andersson, Thomas; Boren, Hans; Dario, Maarten; Allard, Bert; Hagberg, Jessica; Kaellstroem, Klas

    2012-09-01

    This report presents a literature review and laboratory work of the degradation of the fibre UP2, as well as an assessment of the effects of its degradation products on Europium sorption onto cement, as an example of their effects on radionuclide migration. All laboratory work was performed by the Swedish groups (Linkoeping and Oerebro Universities), who also performed some of the literature review. The data interpretation was performed by the Spanish team (Amphos 21). SKB has combined the reports of these studies into this common document and has added minor editorial changes. All these changes have been accepted by the authors

  2. Computed tomographic study of aged schizophrenic patients

    International Nuclear Information System (INIS)

    Seno, Haruo; Fujimoto, Akihiko; Ishino, Hiroshi; Shibata, Masahiro; Kuroda, Hiroyuki; Kanno, Hiroshi.

    1997-01-01

    The width of interhemispheric fissure, lateral ventricles and third ventricle were measured using cranial computed tomography (CT; linear method) in 45 elderly inpatients with chronic schizophrenia and in 28 age-matched control subjects. Twenty-three patients were men and 22 were women. In addition, Mini-Mental State Examination, Brief Psychiatric Rating Scale (BPRS) and a subclass of BPRS were undertaken in all patients. There is a significant enlargement of the maximum width of the interhemispheric fissure (in both male and female) and a significant enlargement of ventricular system (more severe in men than in women) in aged schizophrenics, as seen with CT, compared with normal controls. These findings are consistent with previous studies of non-aged schizophrenic patients. Based upon the relation between psychiatric symptoms and CT findings, the most striking is a significant negative correlation between the third ventricle enlargement and the positive and depressive symptoms in all patients. This result suggests that the advanced third ventricle enlargement may decrease these symptoms in aged schizophrenics. (author)

  3. Lifetimes of organic photovoltaics: Combining chemical and physical characterisation techniques to study degradation mechanisms

    DEFF Research Database (Denmark)

    Norrman, K.; Larsen, N.B.; Krebs, Frederik C

    2006-01-01

    Degradation mechanisms of a photovoltaic device with an Al/C-60/C-12-PSV/PEDOT:PSS/ITO/glass geometry was studied using a combination of in-plane physical and chemical analysis techniques: TOF-SIMS, AFM, SEM, interference microscopy and fluorescence microscopy. A comparison was made between...

  4. A Kinetic Degradation Study of Curcumin in Its Free Form and Loaded in Polymeric Micelles

    NARCIS (Netherlands)

    Naksuriya, Ornchuma; van Steenbergen, Mies J.; Sastre Torano, Javier; Okonogi, Siriporn; Hennink, Wim E.

    Curcumin, a phenolic compound, possesses many pharmacological activities and is under clinical evaluation to treat different diseases. However, conflicting data about its stability have been reported. In this study, the kinetic degradation of curcumin from a natural curcuminoid mixture under various

  5. Degradation Studies on LiFePO4 cathode

    DEFF Research Database (Denmark)

    Scipioni, Roberto; Jørgensen, Peter Stanley; Hjelm, Johan

    2014-01-01

    Lithium-ion batteries are a promising technology for automotive application, but limited performance and lifetime is still a big issue. The aim of this work is to study and address degradation processes which affect LiFePO4 (LFP) cathodes - one of the most common cathodes in commercial Li...

  6. Aging of snubbers in nuclear service: Phase I study results and Phase II plans

    International Nuclear Information System (INIS)

    Goodman, R.L.; Bush, S.H.; Page, R.E.

    1988-01-01

    Two major research areas were investigated in the Phase I snubber aging studies. The first area involved a preliminary evaluation of the effects of various aging mechanisms on snubber operation; failure modes of mechanisms were identified and their contributions to aging degradation were assessed relative to other failure modes. The second area involved estimating the efficacy of existing tests and examinations that are intended to determine the effects of aging and degradation. Available data on snubber behavior and operating experience were reviewed, using licensee event reports and other historical data for the 10-year period from 1973 through 1983. Value-impact was considered in terms of (1) exposure of workers to radioactive environments for examination/testing and (2) the cost for expansion of the snubber testing program due to failed snubbers. Results from the Phase I studies identified the need to modify or improve examination and testing procedures to enhance snubber reliability. Based on the results of the Phase I snubber studies, the seals and fluids were identified as the two principal elements affected by aging degradation in hydraulic snubbers. Phase II work, which was initiated in FY 1987, will develop cooperative activities between PNL and operating utilities through the Snubber Utility Group (SNUG), who will work to establish a strong data and experience base for both hydraulic and mechanical snubbers based on actual operating and maintenance history at nuclear power plants. Application guidelines for snubbers will be recommended based on the study results

  7. Organic Tanks Safety Program: Waste aging studies

    International Nuclear Information System (INIS)

    Camaioni, D.M.; Samuels, W.D.; Lenihan, B.D.; Clauss, S.A.; Wahl, K.L.; Campbell, J.A.

    1994-11-01

    The underground storage tanks at the Hanford Complex contain wastes generated from many years of 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 on several specific safety issues, including potential energy releases from these tanks. This report details the first year's findings of a study charged with determining how thermal and radiological processes may change the composition of organic compounds disposed to the tank. Their approach relies on literature precedent, experiments with simulated waste, and studies of model reactions. During the past year, efforts have focused on the global reaction kinetics of a simulated waste exposed to γ radiation, the reactions of organic radicals with nitrite ion, and the decomposition reactions of nitro compounds. In experiments with an organic tank non-radioactive simulant, the authors found that gas production is predominantly radiolytically induced. Concurrent with gas generation they observe the disappearance of EDTA, TBP, DBP and hexone. In the absence of radiolysis, the TBP readily saponifies in the basic medium, but decomposition of the other compounds required radiolysis. Key organic intermediates in the model are C-N bonded compounds such as oximes. As discussed in the report, oximes and nitro compounds decompose in strong base to yield aldehydes, ketones and carboxylic acids (from nitriles). Certain aldehydes can react in the absence of radiolysis to form H 2 . Thus, if the pathways are correct, then organic compounds reacting via these pathways are oxidizing to lower energy content. 75 refs

  8. Degradation of cellulose at the wet-dry interface. II. Study of oxidation reactions and effect of antioxidants.

    Science.gov (United States)

    Jeong, Myung-Joon; Dupont, Anne-Laurence; de la Rie, E René

    2014-01-30

    To better understand the degradation of cellulose upon the formation of a tideline at the wet-dry interface when paper is suspended in water, the production of chemical species involved in oxidation reactions was studied. The quantitation of hydroperoxides and hydroxyl radicals was carried out in reverse phase chromatography using triphenylphosphine and terephthalic acid, respectively, as chemical probes. Both reactive oxygen species were found in the tideline immediately after its formation, in the range of micromoles and nanomoles per gram of paper, respectively. The results indicate that hydroxyl radicals form for the most part in paper before the tideline experiment, whereas hydroperoxides appear to be produced primarily during tideline formation. Iron sulfate impregnation of the paper raised the production of hydroperoxides. After hygrothermal aging in sealed vials the hydroxyl radical content in paper increased significantly. When aged together in the same vial, tideline samples strongly influenced the degradation of samples from other areas of the paper (multi-sample aging). Different types of antioxidants were added to the paper before the tideline experiment to investigate their effect on the oxidation reactions taking place. In samples treated with iron sulfate or artificially aged, the addition of Irgafos 168 (tris(2,4-ditert-butylphenyl) phosphate) and Tinuvin 292 (bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate) reduced the concentration of hydroperoxides and hydroxyl radicals, respectively. Tinuvin 292 was also found to considerably lower the rate of cellulose chain scission reactions during hygrothermal aging of the paper. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. STUDY ON NONINFECTIOUS DERMATOSES IN PAEDIATRIC AGE

    Directory of Open Access Journals (Sweden)

    Ananthi Mahalingam

    2017-09-01

    Full Text Available BACKGROUND Paediatric dermatology is a unique subspecialty in that child is not a miniature adult. Paediatric dermatoses differ from that of the adults in clinical presentation, treatment and prognosis. Various studies from India have shown infections and infestations to be the most common paediatric dermatoses. This study was planned to determine the epidemiological pattern of common noninfectious dermatoses in our paediatric patients as no such data are available from this part of the country. A cross-sectional study was undertaken to study the prevalence of the noninfectious dermatoses in all the new paediatric patients attending the Skin Outpatient Department (OPD at Villupuram Medical College over a period of three years. MATERIALS AND METHODS A total number of 550 children in the age group ranging from newborn to 12 years with noninfectious dermatoses attending the OPD for the first time were enrolled in the study. RESULTS Physiological changes of skin was the most common dermatoses in the newborn age group, while eczema was the most common dermatoses in infants, preschool and school going children. In the infants, eczema was followed by pigmentary disorders, mongolian spots, vascular nevi, ichthyosis, epidermolysis bullosa, alopecia areata and papular urticaria in the order of prevalence. Among preschool going children, eczema was followed by papular urticaria, papulosquamous disorders, pigmentary disorders, hair disorders, nevi, drug reactions, keratinisation disorders, urticaria, etc. In the school going age group, eczema was followed by papulosquamous disorders, pigmentary disorders, papular urticaria, nutritional disorders, ichthyosis, nevi, miliaria, drug reaction, hair disorders, photodermatoses, urticaria, collagen vascular disease and vascular nevi in the order of prevalence. CONCLUSION Eczema, papulosquamous disorders, papular urticaria, pigmentary disorders seem to be the most common noninfectious dermatoses in children. However

  10. In situ degradation studies of two-dimensional WSe₂-graphene heterostructures.

    Science.gov (United States)

    Wang, B; Eichfield, S M; Wang, D; Robinson, J A; Haque, M A

    2015-09-14

    Heterostructures of two-dimensional materials can be vulnerable to thermal degradation due to structural and interfacial defects as well as thermal expansion mismatch, yet a systematic study does not exist in the literature. In this study, we investigate the degradation of freestanding WSe2-graphene heterostructures due to heat and charge flow by performing in situ experiments inside a transmission electron microscope. Experimental results show that purely thermal loading requires higher temperatures (>850 °C), about 150 °C higher than that under combined electrical and thermal loading. In both cases, selenium is the first element to decompose and migration of silicon atoms from the test structure to the freestanding specimen initiates rapid degradation through the formation of tungsten disilicide and silicon carbide. The role of the current flow is to enhance the migration of silicon from the sample holder and to knock-out the selenium atoms. The findings of this study provide fundamental insights into the degradation of WSe2-graphene heterostructures and inspire their application in electronics for use in harsh environments.

  11. Study of silica coatings degradation under laser irradiation and in controlled environment; Etude de la degradation de couches minces de silice sous flux laser et en environnement controle

    Energy Technology Data Exchange (ETDEWEB)

    Becker, S

    2006-11-15

    Performances of optical components submitted to high laser intensities are usually determined by their laser-induced damage threshold. This value represents the highest density of energy (fluence) sustainable by the component before its damage. When submitted to laser fluences far below this threshold, optical performances may also decrease with time. The degradation processes depend on laser characteristics, optical materials, and environment around the component. Silica being the most used material in optics, the aim of this study was to describe and analyse the physical-chemical mechanisms responsible for laser-induced degradation of silica coatings in controlled environment. Experimental results show that degradation is due to the growth of a carbon deposit in the irradiated zone. From these results, a phenomenological model has been proposed and validated with numerical simulations. Then, several technological solutions have been tested in order to reduce the laser-induced contamination of silica coatings. (author)

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

    International Nuclear Information System (INIS)

    Choi, In Kil; Kim, Min Kyu; Hofmayer, Charles; Braverman, Joseph; Nie, Jinsuo

    2009-03-01

    This report describes the research effort performed by BNL for the Year 2 scope of work. This research focused on methods that could be used to represent the long-term behavior of materials used at NPPs. To achieve this BNL reviewed time-dependent models which can approximate the degradation effects of the key materials used in the construction of structures and passive components determined to be of interest in the Year 1 effort. The intent was to review the degradation models that would cover the most common time-dependent changes in material properties for concrete and steel components

  13. Physicochemical properties and radiolytic degradation studies on tri-iso-amyl phosphate (TiAP)

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivasulu, B.; Sivaraman, Nagarajan [Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India). Homi Bhabha National Inst.; Suresh, A.; Rajeswari, S.; Ramanathan, N.; Antony, M.P.; Joseph, M. [Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India). Chemistry Group

    2017-06-01

    The solvent composed of tri-iso-amyl phosphate (TiAP) in n-dodecane (n-DD) is regarded as a promising candidate for reprocessing of spent fuel. In this context, the radiolytic degradation of a solution of TiAP in n-dodecane was investigated by irradiating the solvent to various absorbed dose levels of γ-radiation. The neat extractant or a solution of extractant in n-dodecane was irradiated in the presence of nitric acid. Physicochemical properties such as density, viscosity and interfacial tension (IFT) were measured for unirradiated and irradiated solutions. The extent of degradation was determined by measuring the variation in extraction behavior of U(VI) and Pu(IV) with irradiated solvent systems. Uranium and plutonium retention with irradiated solvents was also measured. The distribution ratio of uranium and plutonium increased with increase in absorbed dose. Effect of alpha degradation was studied by plutonium retention as a function of time using 1.1 M TiAP/n-DD. Laser desorption/ionization mass spectrometric technique was employed to identify the possible radiolytic degradation products. Similar studies were also carried out with tri-n-butyl phosphate (TBP) based solvent system under identical experimental conditions and the results are compared.

  14. Decomposition of clofibric acid in aqueous media by advance oxidation techniques: kinetics study and degradation pathway

    International Nuclear Information System (INIS)

    Syed, M.; Khan, A.M.; Khan, R.A.

    2016-01-01

    This study investigates the decomposition of clofibric acid (CLF) by different advanced oxidation processes (AOPs), such as UV (254 nm), VUV (185 nm), UV / TiO/sub 2/ and VUV / TiO/sub 2/. The removal efficiencies of applied AOPs were compared in the presence and absence of dissolved oxygen. The removal efficiency of the studied AOPs towards degradation of CLF were found in the order of VUV / TiO/sub 2/ + O/sub 2/ > VUV/TiO/sub 2/ + N/sub 2/ > VUV alone > UV / TiO/sub 2/ + O/sub 2/ > UV / TiO/sub 2/ +N/sub 2/ > UV alone. The decomposition kinetics of CLF was found to follow pseudo-first order rate law. VUV / TiO2 process was found to be most cheap and effective one for decomposition of CLF as compared to other applied AOPs in terms of electrical energy per order. Degradation products resulting from the degradation processes were also investigated using UPLC-MS /MS, accordingly degradation pathway was proposed. (author)

  15. Land Sensitivity Analysis of Degradation using MEDALUS model: Case Study of Deliblato Sands, Serbia

    Directory of Open Access Journals (Sweden)

    Kadović Ratko

    2016-12-01

    Full Text Available This paper studies the assessment of sensitivity to land degradation of Deliblato sands (the northern part of Serbia, as a special nature reserve. Sandy soils of Deliblato sands are highly sensitive to degradation (given their fragility, while the system of land use is regulated according to the law, consisting of three zones under protection. Based on the MEDALUS approach and the characteristics of the study area, four main factors were considered for evaluation: soil, climate, vegetation and management. Several indicators affecting the quality of each factor were identified. Each indicator was quantified according to its quality and given a weighting of between 1.0 and 2.0. ArcGIS 9 was utilized to analyze and prepare the layers of quality maps, using the geometric mean to integrate the individual indicator map. In turn, the geometric mean of all four quality indices was used to generate sensitivity of land degradation status map. Results showed that 56.26% of the area is classified as critical; 43.18% as fragile; 0.55% as potentially affected and 0.01% as not affected by degradation. The values of vegetation quality index, expressed as coverage, diversity of vegetation functions and management policy during the protection regime are clearly represented through correlation coefficient (0.87 and 0.47.

  16. In vitro degradation and cell attachment studies of a new electrospun polymeric tubular graft.

    Science.gov (United States)

    Patel, Harsh N; Thai, Kevin N; Chowdhury, Sami; Singh, Raj; Vohra, Yogesh K; Thomas, Vinoy

    Electrospinning technique was utilized to engineer a small-diameter (id = 4 mm) tubular graft. The tubular graft was made from biocompatible and biodegradable polymers polycaprolactone (PCL) and poliglecaprone with 3:1 (PCL:PGC) ratio. Enzymatic degradation effect on the mechanical properties and fiber morphology in the presence of lipase enzyme were observed. Significant changes in tensile strength (1.86-1.49 MPa) and strain (245-205 %) were noticed after 1 month in vitro degradation. The fiber breakage was clearly evident through scanning electron microscopy (SEM) after 4 weeks in vitro degradation. Then, the graft was coated with a collagenous protein matrix to impart bioactivity. Human umbilical vein endothelial cells (HUVECs) and aortic artery smooth muscle cells (AoSMCs) attachment on the coated graft were observed in static condition. Further, HUVECs were seeded on the lumen surface of the grafts and exposed to laminar shear stress for 12 h to understand the cell attachment. The coated graft was aged in PBS solution (pH 7.3) at 37 °C for 1 month to understand the coating stability. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) suggested the erosion of the protein matrix from the coated graft under in vitro condition.

  17. 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.

  18. Oxidative degradation of triazine- and sulfonylurea-based herbicides using Fe(VI): The case study of atrazine and iodosulfuron with kinetics and degradation products

    Science.gov (United States)

    The occurrence of common herbicides (Atrazine, ATZ and Iodosufuron, IDS), in waters presents potential risk to human and ecological health. The oxidative degradation of ATZ and IDS by ferrate(VI) (FeVIO42-, Fe(VI)) is studied at different pH levels where kinetically observed se...

  19. Harvard Aging Brain Study: Dataset and accessibility.

    Science.gov (United States)

    Dagley, Alexander; LaPoint, Molly; Huijbers, Willem; Hedden, Trey; McLaren, Donald G; Chatwal, Jasmeer P; Papp, Kathryn V; Amariglio, Rebecca E; Blacker, Deborah; Rentz, Dorene M; Johnson, Keith A; Sperling, Reisa A; Schultz, Aaron P

    2017-01-01

    The Harvard Aging Brain Study is sharing its data with the global research community. The longitudinal dataset consists of a 284-subject cohort with the following modalities acquired: demographics, clinical assessment, comprehensive neuropsychological testing, clinical biomarkers, and neuroimaging. To promote more extensive analyses, imaging data was designed to be compatible with other publicly available datasets. A cloud-based system enables access to interested researchers with blinded data available contingent upon completion of a data usage agreement and administrative approval. Data collection is ongoing and currently in its fifth year. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Influence of different beverages on the force degradation of intermaxillary elastics: an in vitro study

    Directory of Open Access Journals (Sweden)

    Jorge César Borges Leão Filho

    2013-04-01

    Full Text Available Objective: The aim of this study was to evaluate in vitro the effects of frequently ingested beverages on force degradation of intermaxillary elastics. Material and Methods: One hundred and eighty 1/4-inch intermaxillary elastics (TP Orthodontics were immersed into six different beverages: (1 Coca-Cola®; (2 Beer; (3 Orange juice; (4 Red wine; (5 Coffee and (6 artificial saliva (control. The period of immersion was 15 min for the first and second cycles and 30 min for the third to fifth cycles. Tensile forces were read in a tensile testing machine before and after the five immersion cycles. One-way repeated measures ANOVA was used to identify significant differences. Results: Force degradation was seen in all evaluated groups and at all observation periods (p<0.05. A greater degree of degradation was present at the initial periods, decreasing gradually over time. However, no statistically significant differences were seen among groups at the same periods, showing that different groups behaved similarly. Conclusions: The chemical nature of the evaluated beverages was not able to influence the degree of force degradation at all observation periods.

  1. Integrative computational approach for genome-based study of microbial lipid-degrading enzymes.

    Science.gov (United States)

    Vorapreeda, Tayvich; Thammarongtham, Chinae; Laoteng, Kobkul

    2016-07-01

    Lipid-degrading or lipolytic enzymes have gained enormous attention in academic and industrial sectors. Several efforts are underway to discover new lipase enzymes from a variety of microorganisms with particular catalytic properties to be used for extensive applications. In addition, various tools and strategies have been implemented to unravel the functional relevance of the versatile lipid-degrading enzymes for special purposes. This review highlights the study of microbial lipid-degrading enzymes through an integrative computational approach. The identification of putative lipase genes from microbial genomes and metagenomic libraries using homology-based mining is discussed, with an emphasis on sequence analysis of conserved motifs and enzyme topology. Molecular modelling of three-dimensional structure on the basis of sequence similarity is shown to be a potential approach for exploring the structural and functional relationships of candidate lipase enzymes. The perspectives on a discriminative framework of cutting-edge tools and technologies, including bioinformatics, computational biology, functional genomics and functional proteomics, intended to facilitate rapid progress in understanding lipolysis mechanism and to discover novel lipid-degrading enzymes of microorganisms are discussed.

  2. FT-Raman spectroscopy study of organic matrix degradation in nanofilled resin composite.

    Science.gov (United States)

    Soares, Luís Eduardo Silva; Nahórny, Sídnei; Martin, Airton Abrahão

    2013-04-01

    This in vitro study evaluated the effect of light curing unit (LCU) type, mouthwashes, and soft drink on chemical degradation of a nanofilled resin composite. Samples (80) were divided into eight groups: halogen LCU, HS--saliva (control); HPT--Pepsi Twist®; HLC--Listerine®; HCP--Colgate Plax®; LED LCU, LS--saliva (control); LPT--Pepsi Twist®; LLC--Listerine®; LCP--Colgate Plax®. The degree of conversion analysis and the measure of the peak area at 2,930 cm-1 (organic matrix) of resin composite were done by Fourier-transform Raman spectroscopy (baseline, after 7 and 14 days). The data were subjected to multifactor analysis of variance (ANOVA) at a 95% confidence followed by Tukey's HSD post-hoc test. The DC ranged from 58.0% (Halogen) to 59.3% (LED) without significance. Differences in the peak area between LCUs were found after 7 days of storage in S and PT. A marked increase in the peak intensity of HLC and LLC groups was found. The soft-start light-activation may influence the chemical degradation of organic matrix in resin composite. Ethanol contained in Listerine® Cool Mint mouthwash had the most significant degradation effect. Raman spectroscopy is shown to be a useful tool to investigate resin composite degradation.

  3. A comparative study on the radiation induced degradation of chlorinated organics and water

    International Nuclear Information System (INIS)

    Bekboelet, M.; Balcioglu, A.I.; Getoff, N.

    1998-01-01

    Complete text of publication follows. Radiation induced degradation of chlorinated benzaldehydes has been studied by the application of UV-photolysis, UV-assisted catalytic oxidation and gamma radiolysis processes. The degradation was followed in terms of the substrate removal and formation of the decomposition products such as chloride and formaldehyde. Formation of the acidic compounds were also determined by the pH decrease during irradiation periods. The below given table summarizes the obtained results in terms of photochemical G (G PH )values. The main idea of this paper was to evaluate the applied processes in relation to the end products rather and to compare the efficiency of the methods. Besides, chloride and formaldehyde formation, the substrate degradation and formation of the stable end products, were followed by HPLC analyses. Hydroxylated parent compounds chlorophenols, benzaldehyde were also detected. Formation of muconic acid through ring opening as well as the formation of lower molecular weight organic acids by decomposition such as oxalic, citric, tartaric and formic acids were observed with respect the applied oxidation process. Depending on the formed stable end products and the related probable reaction mechanisms, isomeric positions were found to be selective toward oxidative degradation

  4. Preformulation stability study of the EGFR inhibitor HKI-272 (Neratinib) and mechanism of degradation.

    Science.gov (United States)

    Lu, Qinghong; Ku, Mannching Sherry

    2012-03-01

    The stability in solution of HKI-272 (Neratinib) was studied as a function of pH. The drug is most stable from pH 3 to 4, and degradation rate increases rapidly around pH 6 and appears to approach a maximum asymptotic limit in the range of pH 812. Pseudo first-order reaction kinetics was observed at all pH values. The structure of the major degradation product indicates that it is formed by a cascade of reactions within the dimethylamino crotonamide group of HKI-272. It is assumed that the rate-determining step is the initial isomerization from allyl amine to enamine functionality, followed by hydrolysis and subsequent cyclization to a stable lactam. The maximum change in degradation rate as a function of pH occurs at about pH 6, which corresponds closely to the theoretical pKa value of the dimethylamino group of HKI-272 when accounting for solvent/temperature effects. The observed relationship between pH and degradation rate is discussed, and a self-catalyzed mechanism for the allylamine-enamine isomerization reaction is proposed. The relevance of these findings to other allylamine drugs is discussed in terms of the relative stability of the allylic anion intermediate through which, the isomerization occurs.

  5. Structure elucidation and degradation kinetic study of Ofloxacin using surface enhanced Raman spectroscopy

    Science.gov (United States)

    El-Zahry, Marwa R.; Lendl, Bernhard

    2018-03-01

    A simple, fast and sensitive surface enhanced Raman spectroscopy (SERS) method for quantitative determination of fluoroquinolone antibiotic Ofloxacin (OFX) is presented. Also the stability behavior of OFX was investigated by monitoring the SERS spectra of OFX after various degradation processes. Acidic, basic and oxidative force degradation processes were applied at different time intervals. The forced degradation conditions were conducted and followed using SERS method utilizing silver nanoparticles (Ag NPs) as a SERS substrate. The Ag NPs colloids were prepared by reduction of silver nitrate using polyethyelene glycol (PEG) as a reducing and stabilizing agent. Validation tests were done in accordance with International Conference on Harmonization (ICH) guidelines. The calibration curve with a correlation coefficient (R = 0.9992) was constructed as a relationship between the concentration range of OFX (100-500 ng/ml) and SERS intensity at 1394 cm- 1 band. LOD and LOQ values were calculated and found to be 23.5 ng/ml and 72.6 ng/ml, respectively. The developed method was applied successfully for quantitation of OFX in different pharmaceutical dosage forms. Kinetic parameters were calculated including rate constant of the degradation of the studied antibiotic.

  6. Study of aliphatic-aromatic copolyester degradation in sandy soil and its ecotoxicological impact.

    Science.gov (United States)

    Rychter, Piotr; Kawalec, Michał; Sobota, Michał; Kurcok, Piotr; Kowalczuk, Marek

    2010-04-12

    Degradation of poly[(1,4-butylene terephthalate)-co-(1,4-butylene adipate)] (Ecoflex, BTA) monofilaments (rods) in standardized sandy soil was investigated. Changes in the microstructure and chemical composition distribution of the degraded BTA samples were evaluated and changes in the pH and salinity of postdegradation soil, as well as the soil phytotoxicity impact of the degradation products, are reported. A macroscopic and microscopic evaluation of the surface of BTA rod samples after specified periods of incubation in standardized soil indicated erosion of the surface of BTA rods starting from the fourth month of their incubation, with almost total disintegration of the incubated BTA material observed after 22 months. However, the weight loss after this period of time was about 50% and only a minor change in the M(w) of the investigated BTA samples was observed, along with a slight increase in the dispersity (from an initial 2.75 up to 4.00 after 22 months of sample incubation). The multidetector SEC and ESI-MS analysis indicated retention of aromatic chain fragments in the low molar mass fraction of the incubated sample. Phytotoxicity studies revealed no visible damage, such as necrosis and chlorosis, or other inhibitory effects, in the following plants: radish, cres, and monocotyledonous oat, indicating that the degradation products of the investigated BTA copolyester are harmless to the tested plants.

  7. Micro- and nano-scale characterization to study the thermal degradation of cement-based materials

    International Nuclear Information System (INIS)

    Lim, Seungmin; Mondal, Paramita

    2014-01-01

    The degradation of hydration products of cement is known to cause changes in the micro- and nano-structure, which ultimately drive thermo-mechanical degradation of cement-based composite materials at elevated temperatures. However, a detailed characterization of these changes is still incomplete. This paper presents results of an extensive experimental study carried out to investigate micro- and nano-structural changes that occur due to exposure of cement paste to high temperatures. Following heat treatment of cement paste up to 1000 °C, damage states were studied by compressive strength test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) atomic force microscopy (AFM) and AFM image analysis. Using experimental results and research from existing literature, new degradation processes that drive the loss of mechanical properties of cement paste are proposed. The development of micro-cracks at the interface between unhydrated cement particles and paste matrix, a change in C–S–H nano-structure and shrinkage of C–S–H, are considered as important factors that cause the thermal degradation of cement paste. - Highlights: • The thermal degradation of hydration products of cement is characterized at micro- and nano-scale using scanning electron microscopy (SEM) and atomic force microscopy (AFM). • The interface between unhydrated cement particles and the paste matrix is considered the origin of micro-cracks. • When cement paste is exposed to temperatures above 300 ºC, the nano-structure of C-S-H becomes a more loosely packed globular structure, which could be indicative of C-S-H shrinkage

  8. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

    International Nuclear Information System (INIS)

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-01-01

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits

  9. Shelf life and outdoor degradation studies of organic bulk heterojunction solar cells

    Science.gov (United States)

    Gergova, R.; Sendova-Vassileva, M.; Popkirov, G.; Gancheva, V.; Grancharov, G.

    2018-03-01

    We studied the degradation of different types of bulk heterojunction devices, in which the materials comprising the active layer and/or the materials used for the back electrode are varied. The devices are deposited on ITO covered glass and have the structure PEDOT:PSS/BHJ/Me, where PEDOT:PSS is the hole transport layer, BHJ (bulk heterojunction) is the active layer comprising a polymer donor (e.g. PTB7, PCDTBT) and a fullerene derivative acceptor (e.g. PC60BM, PC70BM) deposited by spin coating, Me is the metal back contact, which is either Ag or Al deposited by magnetron sputtering or thermal evaporation. The device performance was monitored after storage in the dark at ambient conditions by following the evolution of the J-V curve over time. Results of real conditions outdoor degradation studies are also presented. The stability of the different solar cell structures studied is compared.

  10. Comparative study of modified polypropylene nanocomposites under environment and accelerated ageing conditions

    International Nuclear Information System (INIS)

    Komatsu, Luiz Gustavo Hiroki

    2016-01-01

    The understanding of degradation mechanism action on the polymer nanocomposites in face of weathering (UV light, heat, acid rain, among others), is the key for development of new additives and new applications. In this work the nanocomposite synthesis was carried in molten state, using twin-screw extruder. The polymer matrix was the HMS-PP (high melt polypropylene) synthesized by gamma irradiation and the nanometric inorganic component was the montmorillonite clay. For better compatibilization between the matrix and clay, it were used maleic anhydride as coupling agent. For environment and in oven accelerated aging assays, the dumbbell samples were prepared under hot pressing. The characterization of clay addition effects and aging effects on the nanocomposites, required the use of techniques of Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Fourier Transformed Infrared Spectroscopy (FT-IR), Xray Fluorescence (WDXRF), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and mechanical properties. Samples with 0.1; 1; 3; 5; 10 % of clay were tested. The sample with 5% of clay showed better stability on the environmental assay and accelerated aging in oven assay. On the other hand, the sample with higher percent of clay (10%), was more degraded under on environmental aging than under accelerated aging in stove. In this case, became more resistant until 56 days of assay. On the studied concentrations (less than ≤ 3%) of clay, it can be seen an equilibrium between barrier effect and metallic ions action accelerating the degradative process. (author)

  11. Estimation of Correlation between Chronological Age, Skeletal Age and Dental Age in Children- A Cross-sectional Study.

    Science.gov (United States)

    Macha, Madhulika; Lamba, Bharti; Avula, Jogendra Sai Sankar; Muthineni, Sridhar; Margana, Pratap Gowd Jai Shankar; Chitoori, Prasad

    2017-09-01

    In the modern era, identification and determination of age is imperative for diversity of reasons that include disputed birth records, premature delivery, legal issues and for validation of birth certificate for school admissions, adoption, marriage, job and immigration. Several growth assessment parameters like bone age, dental age and the combination of both have been applied for different population with variable outcomes. It has been well documented that the chronological age does not necessarily correlate with the maturational status of a child. Hence, efforts were made to determine a child's developmental age by using dental age (calcification of teeth) and skeletal age (skeletal maturation). The present study was aimed to correlate the chronological age, dental age and skeletal age in children from Southeastern region of Andhra Pradesh, India. Out of the total 900 screened children, only 100 subjects between age groups of 6-14 years with a mean age of 11.3±2.63 for males and 10.77±2.24 for females were selected for the study. Dental age was calculated by Demirjian method and skeletal age by modified Middle Phalanx of left hand third finger (MP3) method. Pearson's and Spearman's correlation tests were done to estimate the correlation between chronological, dental and skeletal ages among study population. There was a significant positive correlation between chronological age, dental age and all stages of MP3 among males. Similar results were observed in females, except for a non-significant moderate correlation between chronological age and dental age in the H stage of the MP3 region. The results of the present study revealed correlation with statistical significance (p<0.05) between chronological, dental and skeletal ages among all the subjects (48 males and 52 females) and females attained maturity earlier than males in the present study population.

  12. Comparative study of the selective degradations of two enantiomers in the racemate and an enriched concentration of indoxacarb in soils.

    Science.gov (United States)

    Zhang, Yu-Ping; Hu, De-Yu; Ling, Hu-Rong; Zhong, Lei; Huang, An-Xiang; Zhang, Kan-Kan; Song, Bao-An

    2014-09-17

    In this study, selective degradations of the two enantiomers of indoxacarb in the concentrate (2.33S/1R) and racemate (1S/1R) are examined. The absolute configurations of indoxacarb enantiomers were determined using X-ray diffraction. The results showed that in two alkaline soils, the S-(+)-indoxacarb was preferentially degraded in both the concentrate and racemate. In one acid soil, the two enantiomers degraded no-selectivity. In another acid soil and one neutral soil, the R-(-)-indoxacarb was preferentially degraded in both the concentrate and racemate. Indoxacarb enantiomers were configurationally stable in the five soils, and no interconversion was observed during the incubation. Because no significant difference in degradation was observed after samples were sterilized, the observed enantioselectivity may be attributed primarily to microbial activity in soils. The results indicate that the selective degradation behavior was the same for both formulations that were tested.

  13. Chemical degradation of proton conducting perflurosulfonic acid ionomer membranes studied by solid-state nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ghassemzadeh, L. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Marrony, M. [European Institute for Energy Research, Emmy-Noether-Strasse 11, D-76131 Karlsruhe (Germany); Barrera, R. [Edison, Via Giorgio La Pira, 2, I-10028 Trofarello (Italy); Kreuer, K.D.; Maier, J. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Mueller, K. [Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

    2009-01-15

    The degradation of two different types of perfluorinated polymer membranes, Nafion and Hyflon Ion, has been examined by solid-state {sup 19}F and {sup 13}C NMR spectroscopy. This spectroscopic technique is demonstrated to be a valuable tool for the study of the membrane structure and its alterations after in situ degradation in a fuel cell. The structural changes in different parts of the polymers are clearly distinguished, which provides unique insight into details of the degradation processes. The experimental NMR spectra prove that degradation mostly takes place within the polymer side chains, as reflected by the intensity losses of NMR signals associated with SO{sub 3}H, CF{sub 3}, OCF{sub 2} and CF groups. The integral degree of degradation is found to decrease with increasing membrane thickness while for a given thickness, Hyflon Ion appears to degrade less than Nafion. (author)

  14. Short-term rhizosphere effect on available carbon sources, phenanthrene degradation and active microbiome in an aged-contaminated industrial soil

    Directory of Open Access Journals (Sweden)

    François eThomas

    2016-02-01

    Full Text Available Over the last decades, understanding of the effects of plants on soil microbiomes has greatly advanced. However, knowledge on the assembly of rhizospheric communities in aged-contaminated industrial soils is still limited, especially with regard to transcriptionally active microbiomes and their link to the quality or quantity of carbon sources. We compared the short-term (2-10 days dynamics of bacterial communities and potential PAH-degrading bacteria in bare or ryegrass-planted aged-contaminated soil spiked with phenanthrene, put in relation with dissolved organic carbon sources and polycyclic aromatic hydrocarbon (PAH pollution. Both resident and active bacterial communities (analyzed from DNA and RNA, respectively showed higher species richness and smaller dispersion between replicates in planted soils. Root development strongly favored the activity of Pseudomonadales within the first two days, and of members of Actinobacteria, Caulobacterales, Rhizobiales and Xanthomonadales within 6-10 days. Plants slowed down the dissipation of phenanthrene, while root exudation provided a cocktail of labile substrates that might preferentially fuel microbial growth. Although the abundance of PAH-degrading genes increased in planted soil, their transcription level stayed similar to bare soil. In addition, network analysis revealed that plants induced an early shift in the identity of potential phenanthrene degraders, which might influence PAH dissipation on the long-term.

  15. Evidence for age-related performance degradation of (241)Am foil sources commonly used in UK schools.

    Science.gov (United States)

    Whitcher, R; Page, R D; Cole, P R

    2014-06-01

    The characteristics of alpha radiation have for decades been demonstrated in UK schools using small sealed (241)Am sources. There is a small but steady number of schools who report a considerable reduction in the alpha count rate detected by an end-window GM detector compared with when the source was new. This cannot be explained by incorrect apparatus or set-up, foil surface contamination, or degradation of the GM detector. The University of Liverpool and CLEAPSS collaborated to research the cause of this performance degradation. The aim was to find what was causing the performance degradation and the ramifications for both the useful and safe service life of the sources. The research shows that these foil sources have greater energy straggling with a corresponding reduction in spectral peak energy. A likely cause for this increase in straggling is a significant diffusion of the metals over time. There was no evidence to suggest the foils have become unsafe, but precautionary checks should be made on old sources.

  16. Thermal degradation of ligno-cellulosic fuels. DSC and TGA studies

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, V.; Cancellieri, D.; Leoni, E. [SPE-CNRS UMR 6134, University of Corsica, Campus Grossetti, BP 52, 20250 Corti (France)

    2006-12-01

    The scope of this work was to show the utility of thermal analysis and calorimetric experiments to study the thermal oxidative degradation of Mediterranean scrubs. We investigated the thermal degradation of four species; DSC and TGA were used under air sweeping to record oxidative reactions in dynamic conditions. Heat released and mass loss are important data to be measured for wildland fires modelling purpose and fire hazard studies on ligno-cellulosic fuels. Around 638 and 778K, two dominating and overlapped exothermic peaks were recorded in DSC and individualized using a experimental and numerical separation. This stage allowed obtaining the enthalpy variation of each exothermic phenomenon. As an application, we propose to classify the fuels according to the heat released and the rate constant of each reaction. TGA experiments showed under air two successive mass loss around 638 and 778K. Both techniques are useful in order to measure ignitability, combustibility and sustainability of forest fuels. (author)

  17. Studies on Nano-Engineered TiO2 Photo Catalyst for Effective Degradation of Dye

    Science.gov (United States)

    Sowmya, S. R.; Madhu, G. M.; Hashir, Mohammed

    2018-02-01

    All Heterogeneous photo catalysis employing efficient photo-catalyst is the advanced dye degradation technology for the purification of textile effluent. The present work focuses on Congo red dye degradation employing synthesized Ag doped TiO2 nanoparticles as photocatalyst which is characterized using SEM, XRD and FTIR. Studies are conducted to study the effect of various parameters such as initial dye concentration, catalyst loading and pH of solution. Ag Doped TiO2 photocatalyst improve the efficacy of TiO2 by reducing high band gap and electron hole recombination of TiO2. The reaction kinetics is analyzed and the process is found to follow pseudo first order kinetics.

  18. Study The Properties and Weight Loss Degradation of The Blend LDPE/Cellulose in Soil Environment

    Directory of Open Access Journals (Sweden)

    Zuhair Jabbar Abdul Ameer

    2017-05-01

    Full Text Available Wider applications of polyethylene (PE in packaging and agriculture have raised serious issue of waste disposal and pollution. Therefore, it is necessary to raise its biodegradability by additives.In this study, we will add cellulose to low density polyethylene to prepare polymer blend have ability to degradation in soil environment.The samples were prepared by using twin screw extruder.LDPE and CELL have been mixing with different weight proportions, and studied their properties in order to determine its compliance with the required specifications to be able to be used biodegradable polymers. To improve the viability of decomposition PEG has been added to the resulting blend. Several tests were applied to identify those properties such as tensile,hardness, density and creep test. FTIR, digital microscope and SEM test acheved in order to determine the miscibility and blend morphology befor and after degradation.The results show that,the blend weight loss increase with increasing CELL percent.

  19. Ageing studies for the ATLAS MDT muonchambers and development of a gas filter to prevent drift tube ageing

    International Nuclear Information System (INIS)

    Koenig, S.

    2008-01-01

    The muon spectrometer of the ATLAS detector, which is currently assembled at the LHC accelerator at CERN, uses drift tubes as basic detection elements over most of the solid angle. The performance of these monitored drift tubes (MDTs), in particular their spatial resolution of 80 μm, determines the precision of the spectrometer. If ageing effects occur, the precision of the drift tubes will be degraded. Hence ageing effects have to be minimized or avoided altogether if possible. Even with a gas mixture of Ar:CO 2 =93:7, which was selected for its good ageing properties, ageing effects were observed in test systems. They were caused by small amounts of impurities, in particular volatile silicon compounds. Systematic studies revealed the required impurity levels deteriorating the drift tubes to be well below 1 ppm. Many components of the ATLAS MDT gas system are supplied by industry. In a newly designed ageing experiment in Freiburg these components were validated for their use in ATLAS. With a fully assembled ATLAS gas distribution rack as test component ageing effects were observed. It was therefore decided to install gas filters in the gas distribution lines to remove volatile silicon compounds efficiently from the gas mixture. Finally a filter was designed that can adsorb up to 5.5 g of volatile silicon compounds, hereby reducing the impurities in the outlet gas mixture to less than 30 ppb. (orig.)

  20. Ageing studies for the ATLAS MDT muonchambers and development of a gas filter to prevent drift tube ageing

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, S.

    2008-01-15

    The muon spectrometer of the ATLAS detector, which is currently assembled at the LHC accelerator at CERN, uses drift tubes as basic detection elements over most of the solid angle. The performance of these monitored drift tubes (MDTs), in particular their spatial resolution of 80 {mu}m, determines the precision of the spectrometer. If ageing effects occur, the precision of the drift tubes will be degraded. Hence ageing effects have to be minimized or avoided altogether if possible. Even with a gas mixture of Ar:CO{sub 2}=93:7, which was selected for its good ageing properties, ageing effects were observed in test systems. They were caused by small amounts of impurities, in particular volatile silicon compounds. Systematic studies revealed the required impurity levels deteriorating the drift tubes to be well below 1 ppm. Many components of the ATLAS MDT gas system are supplied by industry. In a newly designed ageing experiment in Freiburg these components were validated for their use in ATLAS. With a fully assembled ATLAS gas distribution rack as test component ageing effects were observed. It was therefore decided to install gas filters in the gas distribution lines to remove volatile silicon compounds efficiently from the gas mixture. Finally a filter was designed that can adsorb up to 5.5 g of volatile silicon compounds, hereby reducing the impurities in the outlet gas mixture to less than 30 ppb. (orig.)

  1. Ageing studies for the ATLAS MDT Muonchambers and development of a gas filter to prevent drift tube ageing

    CERN Document Server

    König, Stefan

    2008-01-01

    The muon spectrometer of the ATLAS detector at CERN uses drift tubes as basic detection elements over most of the solid angle. The performance of these monitored drift tubes (MDTs), in particular their spatial resolution of 80 µm, determines the precision of the spectrometer. If ageing effects occur, the precision of the drift tubes will be degraded. Hence ageing effects have to be minimized or avoided altogether if possible. Even with a gas mixture of Ar:CO2 (93:7), which was selected for its good ageing properties, ageing effects were observed in test systems. They were caused by small amounts of impurities, in particular volatile silicon compounds. Systematic studies revealed the required impurity levels deteriorating the drift tubes to be well below 1 ppm. Many components of the ATLAS MDT gas system are supplied by industry. In a newly designed ageing experiment in Freiburg these components were validated for their use in ATLAS. With a fully assembled ATLAS gas distribution rack as test component ageing ...

  2. Magnesium and its alloys as degradable biomaterials : Corrosion studies using potentiodynamic and EIS electrochemical techniques

    OpenAIRE

    Müller, Wolf Dieter; Nascimento, Maria Lucia; Zeddies, Miriam; Córsico, Mariana; Gassa, Liliana Mabel; Fernández Lorenzo de Mele, Mónica Alicia

    2007-01-01

    Magnesium is potentially useful for orthopaedic and cardiovascular applications. However, the corrosion rate of this metal is so high that its degradation occurs before the end of the healing process. In industrial media the behaviour of several magnesium alloys have been probed to be better than magnesium performance. However, the information related to their corrosion behaviour in biological media is insufficient. The aim of this work is to study the influence of the components of organic f...

  3. Studies on adsorption, reaction mechanisms and kinetics for photocatalytic degradation of CHD, a pharmaceutical waste.

    Science.gov (United States)

    Sarkar, Santanu; Bhattacharjee, Chiranjib; Curcio, Stefano

    2015-11-01

    The photocatalytic degradation of chlorhexidine digluconate (CHD), a disinfectant and topical antiseptic and adsorption of CHD catalyst surface in dark condition has been studied. Moreover, the value of kinetic parameters has been measured and the effect of adsorption on photocatalysis has been investigated here. Substantial removal was observed during the photocatalysis process, whereas 40% removal was possible through the adsorption route on TiO2 surface. The parametric variation has shown that alkaline pH, ambient temperature, low initial substrate concentration, high TiO2 loading were favourable, though at a certain concentration of TiO2 loading, photocatalytic degradation efficiency was found to be maximum. The adsorption study has shown good confirmation with Langmuir isotherm and during the reaction at initial stage, it followed pseudo-first-order reaction, after that Langmuir Hinshelwood model was found to be appropriate in describing the system. The present study also confirmed that there is a significant effect of adsorption on photocatalytic degradation. The possible mechanism for adsorption and photocatalysis has been shown here and process controlling step has been identified. The influences of pH and temperature have been explained with the help of surface charge distribution of reacting particles and thermodynamic point of view respectively. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Cross-border cooperation potential in fostering redevelopment of degraded border areas - a case study approach.

    Science.gov (United States)

    Alexandre Castanho, Rui; Ramírez, Beatriz; Loures, Luis; Fernández-Pozo, Luis; Cabezas, José

    2017-04-01

    Border interactions have reached unprecedented levels in recent decades, not only due to their potential for territorial integration but also considering their role in supranational processes, such as landscape reclamation, infrastructure development and land use planning on European territory. In this scenario, successful examples related to the redevelopment of degraded areas have been showing positive impacts at several levels, such as the social, economic, environmental and aesthetic ones which have ultimately related this process, positively, to sustainability issues. However, concerning to border areas, and due to their inherent legislative and bureaucratic conflicts, the intervention in these areas is more complex. Still, and taking into account previously developed projects and strategies of cross-border cooperation (CBC) in European territory it is possible to identified that the definition of common master plans and common objectives are critical issues to achieve the desired territorial success. Additionally, recent studies have put forward some noteworthy ideas highlighting that it is possible to establish a positive correlation between CBC processes and an increasing redevelopment of degraded border areas, with special focus on the reclamation of derelict landscapes fostering soil reuse and redevelopment. The present research, throughout case study analysis at the Mediterranean level - considering case studies from Portugal, Spain, Monaco and Italy - which presents specific data on border landscape redevelopment, enables us to conclude that CBC processes have a positive influence on the potential redevelopment of degraded border areas, considering not only urban but also rural land. Furthermore, this paper presents data obtained through a public participation process which highlights that these areas present a greater potential for landscape reclamation, fostering resource sustainability and sustainable growth. Keywords: Spatial planning; Land

  5. Neuropathologic Studies of the Baltimore Longitudinal Study of Aging (BLSA)

    Science.gov (United States)

    O’Brien, Richard J.; Resnick, Susan M.; Zonderman, Alan B.; Ferrucci, Luigi; Crain, Barbara J.; Pletnikova, Olga; Rudow, Gay; Iacono, Diego; Riudavets, Miguel A.; Driscoll, Ira; Price, Donald L.; Martin, Lee J.; Troncoso, Juan C.

    2010-01-01

    The Baltimore Longitudinal Study of Aging (BLSA) was established in 1958 and is one the oldest prospective studies of aging in the USA and the world. The BLSA is supported by the National Institute of Aging (NIA) and its mission is to learn what happens to people as they get old and how to sort out changes due to aging and from those due to disease or other causes. In 1986, an autopsy program combined with comprehensive neurologic and cognitive evaluations was established in collaboration with the Johns Hopkins University Alzheimer’s Disease Research Center (ADRC). Since then, 211 subjects have undergone autopsy. Here we review the key clinical neuropathological correlations from this autopsy series. The focus is on the morphological and biochemical changes that occur in normal aging, and the early neuropathological changes of neurodegenerative diseases, especially Alzheimer’s disease (AD). We highlight the combined clinical, pathologic, morphometric, and biochemical evidence of asymptomatic AD, a state characterized by normal clinical evaluations in subjects with abundant AD pathology. We conclude that in some individuals, successful cognitive aging results from compensatory mechanisms that occur at the neuronal level (i.e., neuronal hypertrophy and synaptic plasticity) whereas a failure of compensation may culminate in disease. PMID:19661626

  6. Studies on γ-irradiation-induced-degradation of chloramphenicol in aqueous solution

    International Nuclear Information System (INIS)

    Xie Fang; Ha Yiming; Wang Feng; Zhou Hongjie

    2008-01-01

    The irradiation-induced degradation of chloramphenicol by γ-rays in aqueous solution was studied and the radiolytical products were determined. The relationship among degradation rate, absorbed dose and initial concentration have been explored by comparing the position of maximum absorption peaks of chloramphenicol be- fore and after irradiation using high performance liquid chromatography. The identification of radiolytical products has been conducted using liquid chromatography tandem mass spectrometry. It has been found that the relationship among C/C 0 , absorbed dose and initial concentration can be fit with index curve. After irradiation, more than 30 radiolytical products with stable absorption below 278nm could be determined. 8 major radiolytical products with [M-H] - 353, 337, 335(A), 335(B), 319, 289, 127, 166, which are detected in several different conditions, have been picked up. Their possible structures are deducted. (authors)

  7. Study of the degradation process of polyimide induced by high energetic ion irradiation

    International Nuclear Information System (INIS)

    Severin, Daniel

    2008-01-01

    The dissertation focuses on the radiation hardness of Kapton under extreme radiation environment conditions. To study ion-beam induced modifications, Kapton foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (e.g. Ti, Mo, Au, and U) within a large fluence regime (1 x 10 10 -5 x 10 12 ions/cm 2 ). The irradiated Kapton foils were analysed by means of infrared and UV/Vis spectroscopy, tensile strength measurement, mass loss analysis, and dielectric relaxation spectroscopy. For testing the radiation stability of Kapton at the cryogenic operation temperature (5-10 K) of the superconducting magnets, additional irradiation experiments were performed at the Grand Accelerateur National d' Ions Lourds (GANIL, France) focusing on the online analysis of the outgassing process of small volatile degradation fragments. The investigations of the electrical properties analysed by dielectric relaxation spectroscopy exhibit a different trend: high fluence irradiations with light ions (e.g. Ti) lead to a slight increase of the conductivity, whereas heavy ions (e.g. Sm, Au) cause a drastic change already in the fluence regime of nonoverlapping tracks (5 x 10 10 ions/cm 2 ). Online analysis of the outgassing process during irradiation at cryogenic temperatures shows the release of a variety of small gaseous molecules (e.g. CO, CO 2 , and short hydro carbons). Also a small amount of large polymer fragments is identified. The results allow the following conclusions which are of special interest for the application of Kapton as insulating material in a high-energetic particle radiation environment. a) The material degradation measured with the optical spectroscopy and tensile strength tests are scalable with the dose deposited by the ions. The high correlation of the results allows the prediction of the mechanical degradation with the simple and non-destructive infrared spectroscopy. The degradation curve points to a critical material degradation which

  8. Study of the degradation process of polyimide induced by high energetic ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Severin, Daniel

    2008-09-19

    The dissertation focuses on the radiation hardness of Kapton under extreme radiation environment conditions. To study ion-beam induced modifications, Kapton foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (e.g. Ti, Mo, Au, and U) within a large fluence regime (1 x 10{sup 10}-5 x 10{sup 12} ions/cm{sup 2}). The irradiated Kapton foils were analysed by means of infrared and UV/Vis spectroscopy, tensile strength measurement, mass loss analysis, and dielectric relaxation spectroscopy. For testing the radiation stability of Kapton at the cryogenic operation temperature (5-10 K) of the superconducting magnets, additional irradiation experiments were performed at the Grand Accelerateur National d' Ions Lourds (GANIL, France) focusing on the online analysis of the outgassing process of small volatile degradation fragments. The investigations of the electrical properties analysed by dielectric relaxation spectroscopy exhibit a different trend: high fluence irradiations with light ions (e.g. Ti) lead to a slight increase of the conductivity, whereas heavy ions (e.g. Sm, Au) cause a drastic change already in the fluence regime of nonoverlapping tracks (5 x 10{sup 10} ions/cm{sup 2}). Online analysis of the outgassing process during irradiation at cryogenic temperatures shows the release of a variety of small gaseous molecules (e.g. CO, CO{sub 2}, and short hydro carbons). Also a small amount of large polymer fragments is identified. The results allow the following conclusions which are of special interest for the application of Kapton as insulating material in a high-energetic particle radiation environment. a) The material degradation measured with the optical spectroscopy and tensile strength tests are scalable with the dose deposited by the ions. The high correlation of the results allows the prediction of the mechanical degradation with the simple and non-destructive infrared spectroscopy. The degradation curve points to a

  9. Aging

    International Nuclear Information System (INIS)

    Sasaki, Hideo; Kodama, Kazunori; Yamada, Michiko

    1991-01-01

    The hypothesis that exposure to ionizing radiation accelerates the aging process has been actively investigated at ABCC-RERF since 1958, when longitudinal cohort studies of the Adult Health Study (AHS) and the Life Span Study (LSS) were initiated. In their 1975 overall review of aging studies related to the atomic bomb (A-bomb) survivors, Finch and Beebe concluded that while most studies had shown no correlation between aging and radiation exposure, they had not involved the large numbers of subjects required to provide strong evidence for or against the hypothesis. Extending LSS mortality data up to 1978 did not alter the earlier conclusion that any observed life-shortening was associated primarily with cancer induction rather than with any nonspecific cause. The results of aging studies conducted during the intervening 15 years using data from the same populations are reviewed in the present paper. Using clinical, epidemiological, and laboratory techniques, a broad spectrum of aging parameters have been studied, such as postmortem morphological changes, tests of functional capacity, physical tests and measurements, laboratory tests, tissue changes, and morbidity. With respect to the aging process, the overall results have not been consistent and are generally thought to show no relation to radiation exposure. Although some preliminary results suggest a possible radiation-induced increase in atherosclerotic diseases and acceleration of aging in the T-cell-related immune system, further study is necessary to confirm these findings. In the future, applying the latest gerontological study techniques to data collected from subjects exposed 45 years ago to A-bomb radiation at relatively young ages will present a new body of data relevant to the study of late radiation effects. (author) 103 refs

  10. Study of the degradation of organic molecules complexing radionuclides by using Advanced Oxidation Processes

    International Nuclear Information System (INIS)

    Rekab, K.

    2014-01-01

    This research thesis reports the study of the application of two AOPs (Advanced Oxidation Processes) to degrade and mineralise organic molecules which are complexing radio-elements, and thus to allow their concentrations by trapping on mineral matrices. EDTA (ethylene diamine tetraacetic acid) is chosen as reference organic complexing agent for preliminary tests performed with inactive cobalt 59 before addressing actual nuclear effluents with active cobalt 60. The author first presents the industrial context (existing nuclear wastes, notably liquid effluents and their processing) and proposes an overview of the state of the art on adsorption and precipitation of cobalt (natural and radioactive isotope). Then, the author presents the characteristics of the various studied oxides, the photochemical reactor used to perform tests, experimental techniques and operational modes. Results are then presented regarding various issues: adsorption of EDTA and the Co-EDTA complex, and cobalt precipitation; determination of the lamp photon flow by chemical actinometry and by using the Keitz method; efficiency of different processes (UV, UV/TiO 2 , UV/H 2 O 2 ) to degrade EDTA and to degrade the Co-EDTA complex; processing of a nuclear effluent coming from La Hague pools with determination of decontamination factors

  11. A theoretical and experimental study of the thermal degradation of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Groenli, Morten G.

    1996-12-31

    This thesis relates to the thermal degradation of biomass covering a theoretical and experimental study in two parts. In the first part, there is presented an experimental and modeling work on the pyrolysis of biomass under regimes controlled by chemical kinetics, and the second part presents an experimental and modeling work on the pyrolysis of biomass under regimes controlled by heat and mass transfer. Five different celluloses, and hemicellulose and lignin isolated from birch and spruce have been studied by thermogravimetry. The thermo grams of wood species revealed different weight loss characteristics which can be attributed to their different chemical composition. The kinetic analysis gave activation energies between 210 and 280 kJ/mole for all the celluloses, and a model of independent parallel reactions was successfully used to describe the thermal degradation. In the second part of the thesis there is presented experimental and modeling work on the pyrolysis of biomass under regimes controlled by heat and mass transfer. The effect of heating conditions on the product yields distribution and reacted fraction was investigated. The experiments show that heat flux alters the pyrolysis products as well as the intra particle temperatures to the greatest extent. A comprehensive mathematical model which can simulate drying and pyrolysis of moist wood is presented. The simulation of thermal degradation and heat transport processes agreed well with experimental results. 198 refs., 139 figs., 68 abs.

  12. Aging precursors and degradation effects of SiC-MOSFET modules under highly accelerated power cycling conditions

    DEFF Research Database (Denmark)

    Luo, Haoze; Iannuzzo, Francesco; Blaabjerg, Frede

    2017-01-01

    A highly accelerated power cycling test platform using current source converter for SiC-MOSFET power modules is proposed. The control principles of delta and average junction temperatures are introduced. By using isolated thermal fibers, the junction temperature (Tj) variations can be monitored...... and compared. As a result, the effects of degradation on the static and dynamic characteristics during conventional operation are discussed. Finally, the research results can help examine the failure precursors and then estimate the remaining useful lifetime of SiC MOSFET modules....

  13. Organotin persistence in contaminated marine sediments and porewaters: In situ degradation study using species-specific stable isotopic tracers

    Energy Technology Data Exchange (ETDEWEB)

    Furdek, Martina; Mikac, Nevenka [Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Bueno, Maite; Tessier, Emmanuel; Cavalheiro, Joana [Laboratoire de Chimie Analytique Bio-inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux, CNRS UMR 5254, Université de Pau et des Pays de l’Adour, Hélioparc Pau Pyrénées, 2, Av. P. Angot, 64053 Pau Cedex 9 (France); Monperrus, Mathilde, E-mail: mathilde.monperrus@univ-pau.fr [Laboratoire de Chimie Analytique Bio-inorganique et Environnement, Institut Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux, CNRS UMR 5254, Université de Pau et des Pays de l’Adour, Hélioparc Pau Pyrénées, 2, Av. P. Angot, 64053 Pau Cedex 9 (France)

    2016-04-15

    Highlights: • Limiting step in OTC degradation in sediments is their desorption into porewater. • TBT persistence in contaminated sediments increases in sediments rich in organic matter. • DBT does not accumulate in sediments as degradation product of TBT. • TBT and DBT degradation in porewaters occurs with half-lives from 2.9 to 9.2 days. • PhTs degradation is slower than BuTs degradation in oxic porewaters. - Abstract: This paper provides a comprehensive study of the persistence of butyltins and phenyltins in contaminated marine sediments and presents the first data on their degradation potentials in porewaters. The study’s aim was to explain the different degradation efficiencies of organotin compounds (OTC) in contaminated sediments. The transformation processes of OTC in sediments and porewaters were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Sediment characteristics (organic carbon content and grain size) were determined to elucidate their influence on the degradation processes. The results of this study strongly suggest that a limiting step in OTC degradation in marine sediments is their desorption into porewaters because their degradation in porewaters occurs notably fast with half-lives of 9.2 days for tributyltin (TBT) in oxic porewaters and 2.9 ± 0.1 and 9.1 ± 0.9 days for dibutyltin (DBT) in oxic and anoxic porewaters, respectively. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter.

  14. Organotin persistence in contaminated marine sediments and porewaters: In situ degradation study using species-specific stable isotopic tracers

    International Nuclear Information System (INIS)

    Furdek, Martina; Mikac, Nevenka; Bueno, Maite; Tessier, Emmanuel; Cavalheiro, Joana; Monperrus, Mathilde

    2016-01-01

    Highlights: • Limiting step in OTC degradation in sediments is their desorption into porewater. • TBT persistence in contaminated sediments increases in sediments rich in organic matter. • DBT does not accumulate in sediments as degradation product of TBT. • TBT and DBT degradation in porewaters occurs with half-lives from 2.9 to 9.2 days. • PhTs degradation is slower than BuTs degradation in oxic porewaters. - Abstract: This paper provides a comprehensive study of the persistence of butyltins and phenyltins in contaminated marine sediments and presents the first data on their degradation potentials in porewaters. The study’s aim was to explain the different degradation efficiencies of organotin compounds (OTC) in contaminated sediments. The transformation processes of OTC in sediments and porewaters were investigated in a field experiment using species-specific, isotopically enriched organotin tracers. Sediment characteristics (organic carbon content and grain size) were determined to elucidate their influence on the degradation processes. The results of this study strongly suggest that a limiting step in OTC degradation in marine sediments is their desorption into porewaters because their degradation in porewaters occurs notably fast with half-lives of 9.2 days for tributyltin (TBT) in oxic porewaters and 2.9 ± 0.1 and 9.1 ± 0.9 days for dibutyltin (DBT) in oxic and anoxic porewaters, respectively. By controlling the desorption process, organic matter influences the TBT degradation efficiency and consequently defines its persistence in contaminated sediments, which thus increases in sediments rich in organic matter.

  15. A study of aging effects of barrel Time-Of-Flight system in the BESIII experiment

    Science.gov (United States)

    Liu, Huan-Huan; Sun, Sheng-Sen; Fang, Shuang-Shi; Wu, Zhi; Dai, Hong-Liang; Heng, Yue-Kun; Zhou, Ming; Deng, Zi-Yan; Liu, Huai-Min

    2018-02-01

    The Time-Of-Flight system consisting of plastic scintillation counters plays an important role for particle identification in the BESIII experiment at the BEPCII double ring e+e- collider. Degradation of the detection efficiency of the barrel TOF system has been observed since the start of physical data taking and this effect has triggered intensive and systematic studies about aging effects of the detector. The aging rates of the attenuation lengths and relative gains are obtained based on the data acquired in past several years. This study is essential for ensuring an extended operation of the barrel TOF system in optimal conditions.

  16. Studies of local degradation phenomena in composite cathodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Kerlau, Marie; Marcinek, Marek; Srinivasan, Venkat; Kostecki, Robert M.

    2007-01-01

    LiNi 0.8 Co 0.15 Al 0.05 O 2 and LiNi 1/3 Co 1/3 Mn 1/3 O 2 composite cathodes were cycled in model cells to study interfacial phenomena that could lead to electrode degradation. Ex situ spectroscopic analysis of the tested cathodes, which suffered substantial power and capacity loss, showed that the state of charge (SOC) of oxide particles on the cathode surface was highly non-uniform despite the deep discharge of the Li-ion cell at the end of the test. The inconsistent kinetic behavior of individual oxide particles was attributed to the degradation of electronic pathways within the composite cathodes. A simple theoretical model based on a distributed network showed that an increase of the contact resistance between composite electrode particles may be responsible for non-uniform local kinetic behavior of individual oxide particles and the overall degradation of electrochemical performance of composite electrodes

  17. Kinetic study of adsorption and degradation of aniline, benzoic acid, phenol, and diuron in soil suspensions

    International Nuclear Information System (INIS)

    Dao, T.H.; Lavy, T.L.

    1987-01-01

    Laboratory studies were conducted to investigate the effects of low temperature and accelerated soil-solution contact on soil adsorption of labile organic chemicals. The authors measured the kinetics of adsorption and degradation of 14 C-aniline, 14 C-benzoic acid, 14 C-phenol, and 14 C-diuron in the solution phase at 3 and 22 0 C. In the initial stages of reactions, the adsorption of all four chemicals was instantaneous at both temperatures under accelerated soil and solution mixing. A steady state was observed after the onset of equilibrium for the adsorption reaction for all compounds within 10 to 30 min. Its length varied according to the expected order of susceptibility to microbial degradation, i.e., diuron > aniline > phenol ≥ benzoate. It was apparent that the steady-state period without or in combination with low temperature could be advantageously used to obtain adsorption measurements in microbially active systems. A mechanistic sorption-catalyzed degradation model was evaluated to uncouple mathematically these processes. The model described satisfactorily the disappearance of labile chemicals in soil suspensions. Numerical analysis allowed the concurrent determination of adsorption, desorption, and biodegradation rate coefficients

  18. Influence of different beverages on the force degradation of intermaxillary elastics: an in vitro study.

    Science.gov (United States)

    Leão Filho, Jorge César Borges; Gallo, Daphine Beatriz; Santana, Regis Meller; Guariza-Filho, Odilon; Camargo, Elisa Souza; Tanaka, Orlando Motohiro

    2013-01-01

    The aim of this study was to evaluate in vitro the effects of frequently ingested beverages on force degradation of intermaxillary elastics. One hundred and eighty 1/4-inch intermaxillary elastics (TP Orthodontics) were immersed into six different beverages: (1) Coca-Cola®; (2) Beer; (3) Orange juice; (4) Red wine; (5) Coffee and (6) artificial saliva (control). The period of immersion was 15 min for the first and second cycles and 30 min for the third to fifth cycles. Tensile forces were read in a tensile testing machine before and after the five immersion cycles. One-way repeated measures ANOVA was used to identify significant differences. Force degradation was seen in all evaluated groups and at all observation periods (pdegradation was present at the initial periods, decreasing gradually over time. However, no statistically significant differences were seen among groups at the same periods, showing that different groups behaved similarly. The chemical nature of the evaluated beverages was not able to influence the degree of force degradation at all observation periods.

  19. The degradation of 14C-labelled drilling chemicals in a simulated seabed study

    International Nuclear Information System (INIS)

    Eriksen, D.O.; Songe, P.; Schaanning, M.T.

    2003-01-01

    In an experiment, which lasted nine months, real sea bed sections and naturally occurring sediment dwelling organisms have been used to study the decomposition of today's 'green' chemicals, i.e. drilling mud chemicals comprising a-olefins or esters made from fatty acid extracted from fish. Both types have been shown to be degraded at aerobic conditions at sea bed. However, the fate of the alcoholic part of the ester has been unknown, as was the rate of degradation of the olefin. Both olefin and alcohol were labelled with 14 C at the C1 atom. The results show that the ester hydrolyses quickly and after a lag phase the alcohol is oxidised, while the olefin degrades more slowly. 133 Ba-labelled baryte was used as a bioturbidity marker. The measurements, i.e. scanned sediment columns, show very little bioturbation in the boxes where oil-contaminated sediment was present whereas the control boxes showed more activity from the sediment dwelling organisms down to the depth of the contaminated layer. (author)

  20. Study of Aramid Fiber/Polychloroprene Recycling Process by Thermal Degradation

    Directory of Open Access Journals (Sweden)

    Igor Dabkiewicz

    2016-07-01

    Full Text Available Aramid fiber is an important polymer applied as reinforcement in high-performance composites, which, due its exceptional properties, becomes an excellent impact absorption material. It has been broadly utilized in aeronautic industry and ballistic protection. In aircrafts, it is mainly used in secondary structures, such as fairings, floor panels, and bullet proof structures in helicopters, whereas, in ballistic protection industry, it is applied in automotive armor and bullet proof vest. Under environmental perspective, it is worrying the development and application of composites, which generate proportional discards of these materials, whether originated from manufacturing process, spare parts or end of life cycle. High-performance composite materials like those using aramid fiber are generally difficult to recycle due to their properties and the difficulty for the separation of the components, making their recycling economically unviable. From the characteristics of composite materials and environmental viewpoint, this paper presents a new aramid fiber recycling process. The main objective of this research was to study different recycling methods in aramid fibers/Neoprene® composites. To promote the Neoprene® degradation, it was used a pyrolysis oven with controlled atmosphere and CO 2 injection. For the degraded separation, it was designed a mechanical washing machine in which the most degraded separation occurred. To complete the materials separation, it was employed a manual cleaning process, and, at least to prove the efficacy of the process, it was applied a tensile test in the yarns.

  1. Effect of impurities and electrolyte thickness on degradation of pure magnesium: A finite element study

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, R., E-mail: rodrigo.montoya@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Departamento de Matematicas, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Departamento de Ingenieria Metalurgica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Ciudad Universitaria, 04510 Mexico D.F. Mexico (Mexico); Escudero, M.L., E-mail: escudero@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Garcia-Alonso, M.C., E-mail: crisga@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas, CENIM, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Degradation of Mg due to the presence of impurities by finite element method. Black-Right-Pointing-Pointer A thin film of electrolyte causes galvanic corrosion focused only close on impurities. Black-Right-Pointing-Pointer A thick layer of electrolyte provokes galvanic corrosion extended the whole surface. Black-Right-Pointing-Pointer A higher number of impurities causes galvanic corrosion on the Mg surface independently of electrolyte thickness. Black-Right-Pointing-Pointer The electrolyte thickness is an important variable that affects the in vivo degradation. - Abstract: The aim of this work is to study the degradation of magnesium due to the presence of impurities, by finite element method (FEM), when different thickness of physiological medium bathes the surface. The electrochemical experimental data obtained from polarization curves are used to model mathematically the corrosion process by solving the Laplace equation and the proper boundary conditions by means of FEM. The results show that when Mg is covered by a thin film of electrolyte, galvanic corrosion is focused only on the areas located really close to the cathodic sites, and far from the impurities, the Mg matrix remains near to its corrosion potential with a natural corrosion process. However, if the Mg matrix is completely covered by a thick layer of electrolyte the potentials obtained in the Mg surface far from the impurity are higher than its corrosion potential, so the Mg suffers more severe galvanic corrosion. On the other hand, when a higher number of impurities is considered, the Mg matrix is anodically polarized and it suffers severe galvanic corrosion, independently of h. The thickness of the electrolyte h must be considered as an important variable that affects the in vivo degradation.

  2. Effect of impurities and electrolyte thickness on degradation of pure magnesium: A finite element study

    International Nuclear Information System (INIS)

    Montoya, R.; Escudero, M.L.; García-Alonso, M.C.

    2011-01-01

    Highlights: ► Degradation of Mg due to the presence of impurities by finite element method. ► A thin film of electrolyte causes galvanic corrosion focused only close on impurities. ► A thick layer of electrolyte provokes galvanic corrosion extended the whole surface. ► A higher number of impurities causes galvanic corrosion on the Mg surface independently of electrolyte thickness. ► The electrolyte thickness is an important variable that affects the in vivo degradation. - Abstract: The aim of this work is to study the degradation of magnesium due to the presence of impurities, by finite element method (FEM), when different thickness of physiological medium bathes the surface. The electrochemical experimental data obtained from polarization curves are used to model mathematically the corrosion process by solving the Laplace equation and the proper boundary conditions by means of FEM. The results show that when Mg is covered by a thin film of electrolyte, galvanic corrosion is focused only on the areas located really close to the cathodic sites, and far from the impurities, the Mg matrix remains near to its corrosion potential with a natural corrosion process. However, if the Mg matrix is completely covered by a thick layer of electrolyte the potentials obtained in the Mg surface far from the impurity are higher than its corrosion potential, so the Mg suffers more severe galvanic corrosion. On the other hand, when a higher number of impurities is considered, the Mg matrix is anodically polarized and it suffers severe galvanic corrosion, independently of h. The thickness of the electrolyte h must be considered as an important variable that affects the in vivo degradation.

  3. Size exclusion chromatography and viscometry in paper degradation studies. New Mark-Houwink coefficients for cellulose in cupri-ethylenediamine.

    Science.gov (United States)

    Łojewski, Tomasz; Zieba, Katarzyna; Lojewska, Joanna

    2010-10-15

    The paper deals with the application of size exclusion chromatography (SEC) for the studies of paper degradation phenomena. The goal is to solve some of the technical problems connected with the calibration of multi-detector SEC system and to find the correlation between SEC and viscometric results of degree of polymerization of cellulose. The results gathered for the paper samples degraded by acidic air pollutant (NO(2)) are used as an example of SEC-MALLS application. From the correlation between intrinsic viscosities and absolute value of molecular masses obtained with SEC/MALLS (Multi Angle Laser Light Scattering) technique, Mark-Houwink coefficients for cellulose in cupri-ethylenediamine solution were determined. Thus obtained coefficients were used for the determination of viscometric degree of polymerization (molecular mass) of the aged samples. An excellent correlation was found between the chromatographic values of molecular masses obtained with SEC-UV/VIS detection and the viscometric ones utilizing the improved values of Mark-Houwink coefficients. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Transport and degradation of pesticides in a biopurification system under variable flux Part II: A macrocosm study

    International Nuclear Information System (INIS)

    De Wilde, Tineke; Spanoghe, Pieter; Ryckeboer, Jaak; Jaeken, Peter; Springael, Dirk

    2010-01-01

    Transport of bentazone, isoproturon, linuron, metamitron and metalaxyl were studied under three different flows in macrocosms. The aim was to verify the observations from Part I of the accompanying paper, with an increase in column volume and decrease in chemical and hydraulic load. Very limited breakthrough occurred in the macrocosms for all pesticides, except bentazone, at all flows. From batch degradation experiments, it was observed that the lag time of metamitron and linuron decreased drastically in time for all flows, indicating a growth in the pesticide degrading population. This in contrast to isoproturon and metalaxyl, where an increase in lag time could be observed in time for all flows. From the batch degradation experiments, it could be concluded that the influence of flow on the lag time was minimal and that the inoculation of the pesticide-primed soil had a little surplus value on degradation. - Retention and degradation of pesticides in macrocosms liable to different fluxes.

  5. Transport and degradation of pesticides in a biopurification system under variable flux Part II: A macrocosm study

    Energy Technology Data Exchange (ETDEWEB)

    De Wilde, Tineke, E-mail: dewilde.tineke@gmail.co [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Spanoghe, Pieter [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Ryckeboer, Jaak [Division Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); Jaeken, Peter [PCF-Royal Research Station of Gorsem, De Brede Akker 13, 3800 Sint-Truiden (Belgium); Springael, Dirk [Division Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium)

    2010-10-15

    Transport of bentazone, isoproturon, linuron, metamitron and metalaxyl were studied under three different flows in macrocosms. The aim was to verify the observations from Part I of the accompanying paper, with an increase in column volume and decrease in chemical and hydraulic load. Very limited breakthrough occurred in the macrocosms for all pesticides, except bentazone, at all flows. From batch degradation experiments, it was observed that the lag time of metamitron and linuron decreased drastically in time for all flows, indicating a growth in the pesticide degrading population. This in contrast to isoproturon and metalaxyl, where an increase in lag time could be observed in time for all flows. From the batch degradation experiments, it could be concluded that the influence of flow on the lag time was minimal and that the inoculation of the pesticide-primed soil had a little surplus value on degradation. - Retention and degradation of pesticides in macrocosms liable to different fluxes.

  6. Evolution of the degradation mechanism of pure zinc stent in the one-year study of rabbit abdominal aorta model.

    Science.gov (United States)

    Yang, Hongtao; Wang, Cong; Liu, Chaoqiang; Chen, Houwen; Wu, Yifan; Han, Jintao; Jia, Zichang; Lin, Wenjiao; Zhang, Deyuan; Li, Wenting; Yuan, Wei; Guo, Hui; Li, Huafang; Yang, Guangxin; Kong, Deling; Zhu, Donghui; Takashima, Kazuki; Ruan, Liqun; Nie, Jianfeng; Li, Xuan; Zheng, Yufeng

    2017-11-01

    In the present study, pure zinc stents were implanted into the abdominal aorta of rabbits for 12 months. Multiscale analysis including micro-CT, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and histological stainings was performed to reveal the fundamental degradation mechanism of the pure zinc stent and its biocompatibility. The pure zinc stent was able to maintain mechanical integrity for 6 months and degraded 41.75 ± 29.72% of stent volume after 12 months implantation. No severe inflammation, platelet aggregation, thrombosis formation or obvious intimal hyperplasia was observed at all time points after implantation. The degradation of the zinc stent played a beneficial role in the artery remodeling and healing process. The evolution of the degradation mechanism of pure zinc stents with time was revealed as follows: Before endothelialization, dynamic blood flow dominated the degradation of pure zinc stent, creating a uniform corrosion mode; After endothelialization, the degradation of pure zinc stent depended on the diffusion of water molecules, hydrophilic solutes and ions which led to localized corrosion. Zinc phosphate generated in blood flow transformed into zinc oxide and small amounts of calcium phosphate during the conversion of degradation microenvironment. The favorable physiological degradation behavior makes zinc a promising candidate for future stent applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Controlled swelling and degradation studies of alginate microbeads in dilute natrium-citrate solutions

    Directory of Open Access Journals (Sweden)

    Mitrović Dragana D.

    2010-01-01

    degree after 3 days of staying in 0.2 mM Na-citrate solution were 136.6 ± 2.8 and 30.8 ± 1.3 kPa, respectively. By day 7 in this solution, the beads still appearing structurally intact, further lost their mechanical strength due to continued polymer chain relaxation so that the compression modulus was 20.7 to 22.6 kPa owed almost solely to undegraded polyguluronate parts. Results of these studies are important from a fundamental standpoint for determination of structure and degradation mechanisms of alginate hydrogels but also from a practical point of view for optimization of hydrogel properties and behavior for potential applications in controlled drug release as well as in tissue engineering.

  8. Insights from the past: incorporating long-term landscape evolution in studies of land degradation

    Science.gov (United States)

    Ferro-Vazquez, Cruz; Lang, Carol; Kabora, Tabitha; Thornton-Barnett, Senna; Richer, Suzi; Gallello, Gianni; Stump, Daryl

    2017-04-01

    Modern approaches for assessing land degradation encompass multidisciplinary studies that have allowed a more realistic understanding of the causes and consequences of land degradation. This incipient perspective includes an increasingly important role of the studies of the past, including human history, to understand modern ecosystems and landscapes. Indeed, the current promotion of indigenous resource-use strategies as models of sustainable development was initially prompted by historical studies. However, systematic studies on whether or not indigenous management practices led to land degradation, and therefore their benefits or constraints for sustained use of natural resources, are not truly known. We argue that a joint approach combining the characterization of current soil properties with the archaeological study of traditional agricultural systems can provide insights on their sustainability. Archaeological excavation enables discerning the order in which sediments are deposited and the sequence in which structures are built. This provides data on coincident cultural and ecological change, and a long-term perspective on how agro-ecological systems operated in pre-modern states and the ways in which they resemble or differ from modern contexts. Simultaneously, these changes would have left a physical, chemical and isotopic imprint in soils that can be detected and interpreted to contribute to the production of a "usable past" (Stump, 2013). The premise is: since ancient agricultural sites may provide information on agronomic conditions after centuries to millennia of use, they can help in understanding the ways in which agroecosystems have survived, failed or adapted in the past. This will contribute to a better holistic understanding of social-ecological systems evolution by including a temporal perspective, and to a more nuanced assessment of land degradation and sustainable use. To illustrate this we present the outcome of our research at two traditional

  9. Degradation study of AlAs/GaAs resonant tunneling diode IV curves under influence of high temperatures

    Science.gov (United States)

    Makeev, M. O.; Meshkov, S. A.; Sinyakin, V. Yu

    2017-11-01

    In the present work the thermal degradation of IV curves of AlAs/GaAs resonant tunneling diodes using artificial aging method was investigated. The dependency of AuGeNi specific ohmic contact resistance on time and temperature was determined.

  10. Aging study of the powdered magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Umar Saeed, E-mail: omar_aps@yahoo.co.uk [Department of Physics, University of Peshawar (Pakistan); Rahim, Abdur, E-mail: rahimkhan533@gmail.com [Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Lahore (Pakistan); Khan, Nasrullah [Department of Physics, Kohat University of Science and Technology, Kohat (Pakistan); Muhammad, Nawshad; Rehman, Fozia [Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Lahore (Pakistan); Ahmad, Khalid [Institute of Chemistry, State University of Campinas, PO Box 6154, 13083-970 Campinas, SP (Brazil); Iqbal, Jibran [College of Natural and Health Sciences, Zayed University, 144534 Abu Dhabi (United Arab Emirates)

    2017-03-01

    Magnetite nanoparticles were produced via co-precipitation method and then stored at room temperature for 6 years in aerobic atmosphere. Variations in the inherent solid phase and solid interfacial properties of the prepared magnetite nanoparticles were investigated. For this purpose the fresh and aged samples were characterized using transmission electron microscopy, vibrating sample magnetometer, X-ray diffractometer and energy dispersive X-ray spectrometer. The solid phase transformations of magnetite nanoparticles to maghemite nanoparticles as well as formation of other iron oxides were happened. After aging of 6 years, no change was occurred in the magnetic features; however increase in particle size from 9.6 to 18.5 measured by transmission electron microscopy was confirmed. The crystallite size and vibrating sample magnetometer values were measured before and after aging and found to increase from 8.98 nm and 47.23 emu/g to 16.18 nm and 58.36 emu/g respectively. The formation of other iron oxides, recrystallization and agglomeration during aging process, caused a significant decrease in the specific surface area from 124.43 to 45.00 m{sup 2}/g of the stored sample. - Highlights: • Magnetite nanoparticles (NPs) were produced via co-precipitation method. • Inherent solid phase and interfacial properties of NP were evaluated after 6 years. • The solid phase transformations of magnetite NPs to maghemite NPs was happened. • After aging of 6 years, no change was occurred in the magnetic features.

  11. Aging study of the powdered magnetite nanoparticles

    International Nuclear Information System (INIS)

    Khan, Umar Saeed; Rahim, Abdur; Khan, Nasrullah; Muhammad, Nawshad; Rehman, Fozia; Ahmad, Khalid; Iqbal, Jibran

    2017-01-01

    Magnetite nanoparticles were produced via co-precipitation method and then stored at room temperature for 6 years in aerobic atmosphere. Variations in the inherent solid phase and solid interfacial properties of the prepared magnetite nanoparticles were investigated. For this purpose the fresh and aged samples were characterized using transmission electron microscopy, vibrating sample magnetometer, X-ray diffractometer and energy dispersive X-ray spectrometer. The solid phase transformations of magnetite nanoparticles to maghemite nanoparticles as well as formation of other iron oxides were happened. After aging of 6 years, no change was occurred in the magnetic features; however increase in particle size from 9.6 to 18.5 measured by transmission electron microscopy was confirmed. The crystallite size and vibrating sample magnetometer values were measured before and after aging and found to increase from 8.98 nm and 47.23 emu/g to 16.18 nm and 58.36 emu/g respectively. The formation of other iron oxides, recrystallization and agglomeration during aging process, caused a significant decrease in the specific surface area from 124.43 to 45.00 m"2/g of the stored sample. - Highlights: • Magnetite nanoparticles (NPs) were produced via co-precipitation method. • Inherent solid phase and interfacial properties of NP were evaluated after 6 years. • The solid phase transformations of magnetite NPs to maghemite NPs was happened. • After aging of 6 years, no change was occurred in the magnetic features.

  12. Studies on resin degradation products encountered during purification of plutonium by anion exchange

    International Nuclear Information System (INIS)

    Ramanujam, A.; Dhami, P.S.; Gopalakrishnan, V.; Dhumwad, R.K.

    1991-01-01

    Among the methods available for the purification of plutonium in Purex process, anion exchange method offers several advantages. However, on repeated use, the resin gets degraded due to thermal, radiolytic and chemical attacks resulting in chemical as well as physical damage. Frequently, plutonium product eluted from such resin contains significant quantities of white precipitates. A few anion exchange resins were leached with 8 M HNO 3 at 60-80degC and the resin degradation products (RDP) in the leach-extract were found to give similar precipitates with tetravalent metal ions like Pu(IV), Th(IV) etc. Tetra propyl ammonium hydroxide in 8 M HNO 3 (TPAN) also gave a white precipitate with plutonium similar to the one found in the elution streams. The results indicate that delinked quaternary ammonium functional groups might be responsible for the formation of precipitate. The characteristics of precipitates Th-RDP, Th-TPAN and that isolated from elution stream have been investigated. In a separate study a tentative formula for Th-RDP compound is proposed. The influence of RDP on the extraction of plutonium and other components in Purex process was studied and it was found that RDP complexes metal ions thus marginally affecting the kd values. A spectrophotometric method has been standardised to monitor the extent of degradation of anion exchange resins which is based on the ability of RDP to reduce the colour intensity of Th-thoron complex. This technique can be used to study the stability of the anion exchange resins. (author). 8 refs., 8 tabs., 5 figs.,

  13. Aging

    International Nuclear Information System (INIS)

    Finch, S.C.; Beebe, G.W.

    1975-01-01

    The hypothesis that ionizing radiation accelerates natural aging has been under investigation at the Atomic Bomb Casualty Commission since 1959. Postmortem observations of morphologic and chemical changes, tests of functional capacity, physical tests and measurements, clinical laboratory tests, tissue changes, morbidity, and mortality have all been examined by ABCC investigators interested in this hypothesis. These studies have been beset with conceptual difficulties centered on the definition and measurement of aging. An empirical approach early led to the calculation of an index of physiologic age as a linear combination of age-related tests of various organ systems. Most studies have been negative but have not involved the large numbers that might be required to provide strong evidence for or against the hypothesis. Mortality, however, has been examined on the basis of a large sample and over the period 1950-1972 had provided no support for the hypothesis of radiation-accelerated aging. Ionizing radiation dose, of course shorten human life, but its life-shortening effect appears to be the result of specific radiation-induced disease, especially neoplasms. The hypothesis is now much less attractive than it was 10-20 years ago but still has some value in stimulating research on aging. The experience of the A-bomb survivors provides an unusual opportunity for a definitive test of the hypothesis. (auth.)

  14. Study of the degradation of the mechanical resistance of an alumina

    International Nuclear Information System (INIS)

    Xavier, C.

    1981-02-01

    The strength degradation of a commercial, pure aluminum oxide was investigated in aqueous environment and at ambient temperature in static and dynamic loading, and the applicability of proof testing was studied. The fatigue parameters A and N of the basic equation of subcritical crack growth in ceramics, a sup(.)AK sup(N) sub(I), where a sup(.) is the crack growth rate and K sub(I) is the applied stress intensity factor, were determined from static and dynamic fatigue data using a numerical analysis method based on fracture statistics and fracture mechanics principles which has been published recently. (A.R.H.) [pt

  15. Organic tanks safety program FY96 waste aging studies

    International Nuclear Information System (INIS)

    Camaioni, D.M.; Samuels, W.D.; Linehan, J.C.; Clauss, S.A.; Sharma, A.K.; Wahl, K.L.; Campbell, J.A.

    1996-10-01

    Uranium and plutonium production at the Hanford Site produced large quantities of radioactive by-products and contaminated process chemicals, which are stored in underground tanks awaiting treatment and disposal. Having been made strongly alkaline and then subjected to successive water evaporation campaigns to increase storage capacity, the wastes now exist in the physical forms of salt cakes, metal oxide sludges, and partially saturated aqueous brine solutions. The tanks that contain organic process chemicals mixed with nitrate/nitrite salt wastes may be at risk for fuel- nitrate combustion accidents. The purpose of the Waste Aging Task is to elucidate how chemical and radiological processes will have aged or degraded the organic compounds stored in the tanks. Ultimately, the task seeks to develop quantitative measures of how aging changes the energetic properties of the wastes. This information will directly support efforts to evaluate the hazard as well as to develop potential control and mitigation strategies

  16. Conductivity ageing studies on 1M10ScSZ (M4+=Ce, Hf)

    DEFF Research Database (Denmark)

    Omar, Shobit; Bin Najib, Waqas; Bonanos, Nikolaos

    2011-01-01

    The long-term conductivity stability is tested on zirconia based electrolyte materials for solid oxide fuel cell applications. The ageing studies have been performed on the samples of ZrO2 co-doped with 10mol% of Sc2O3 and 1mol% MO2, where M = Ce or Hf (denoted respectively 1Ce10ScSZ and 1Hf10Sc......SZ) in oxidising and reducing atmospheres, at 600°C for 3000h. At 600°C, these compositions show initial conductivity of around 9–12mS∙cm−1 in air. After 3000h of ageing, no phase transitions are observed in any of the samples. For the first 1000h, the degradation rate is higher than in the subsequent 2000h......; thereafter, conductivity degrades linearly with time for all samples. In air, the loss in the conductivity is lower than in reducing conditions. The 1Ce10ScSZ shows the highest degradation rate of 3.8%/1000h in wet H2/N2 after the first 1000h of ageing. A colour change of the 1Ce10ScSZ sample from white...

  17. Green synthesis, characterization and catalytic degradation studies of gold nanoparticles against congo red and methyl orange.

    Science.gov (United States)

    Umamaheswari, C; Lakshmanan, A; Nagarajan, N S

    2018-01-01

    The present study reports, novel and greener method for synthesis of gold nanoparticles (AuNPs) using 5,7-dihydroxy-6-metoxy-3 ' ,4 ' methylenedioxyisoflavone (Dalspinin), isolated from the roots of Dalbergia coromandeliana was carried out for the first time. The synthesized gold nanoparticles were characterized by UV-Vis spectroscopy, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The observed surface plasmon resonance (SPR) at 532nm in the UV-Vis absorption spectrum indicates the formation of gold nanoparticles. The powder XRD and SAED pattern for synthesized gold nanoparticles confirms crystalline nature. The HR-TEM images showed that the AuNPs formed were small in size, highly monodispersed and spherical in shape. The average particle sizes of the AuNPs are found to be ~10.5nm. The prepared AuNPs were found to be stable for more than 5months without any aggregation. The catalytic degradation studies of the synthesized AuNPs towards degradation of congo red and methyl orange, showed good catalytic in the complete degradation of both the dyes. The reduction catalyzed by gold nanoparticles followed the pseudo-first order kinetics, with a rate constant of 4.5×10 -3 s -1 (R 2 =0.9959) and 1.7×10 -3 s -1 (R 2 =0.9918) for congo red (CR) and methyl orange (MO), respectively. Copyright © 2017. Published by Elsevier B.V.

  18. Aging study on atomic bomb survivors

    International Nuclear Information System (INIS)

    Okajima, Shunzo; Aoyama, Takashi; Norimura, Toshiyuki; Nishimori, Issei; Shiomi, Toshio

    1976-01-01

    This is an ad interim report on the survey which is being performed at the Atomic Disease Institute, Nagasaki University School of Medicine for the acceleration of aging in atomic bomb survivors. The survivors group consisted of 50 females between 40 and 49 years of age who were exposed somewhere within 1.4 km where exposure dose could be estimated accurately and whose mean estimated exposure dose was 225.9+-176.8 rads. The control group consisted of females of the same age group who were exposed at sites more than 2.5 km apart (atmospheric dose 2.9 rads). The items for the judgement of aging included physical measurements, external findings, functional findings, and special tests (urine, blood, pattern of serum protein fraction, and chromosome aberrations). As far as chromosome aberrations were concerned, the number of cells with stable aberrations, Cs, showed differences between the two groups, and the number of cells with exchange-type aberrations was large in the survivors group. No significant differences were observed in the other tests. (Serizawa, K.)

  19. Aging road user studies of intersection safety.

    Science.gov (United States)

    2014-10-01

    Task 1.1 assessed younger (21-35 years), middle-aged (50-64 years), and older (65+) drivers ability to : quickly perceive the presence of marked/unmarked crosswalks and pedestrians within them in computer-based : laboratory tasks that recorded res...

  20. Toxicity assessment of pesticide triclosan by aquatic organisms and degradation studies.

    Science.gov (United States)

    Taştan, Burcu Ertit; Tekinay, Turgay; Çelik, Hatice Sena; Özdemir, Caner; Cakir, Dilara Nur

    2017-12-01

    Triclosan is considered as an important contaminant and is widely used in personal care products as an antimicrobial agent. This study demonstrates the biodegradation of triclosan by two freshwater microalgae and the acute toxicity of triclosan and 2,4-dichlorophenol. The effects of culture media and light on biodegradation of triclosan and the changing morphology of microalgae were systematically studied. Geitlerinema sp. and Chlorella sp. degraded 82.10% and 92.83% of 3.99 mg/L of triclosan at 10 days, respectively. The microalgal growth inhibition assay confirmed absence of toxic effects of triclosan on Chlorella sp., even at higher concentration (50 mg/L) after 72 h exposure. HPLC analysis showed that 2,4-dichlorophenol was produced as degradation product of triclosan by Geitlerinema sp. and Chlorella sp. This study proved to be beneficial to understand biodegradation and acute toxicity of triclosan by microalgae in order to provide aquatic environmental protection. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Application of TAM III to study sensitivity of soil organic matter degradation to temperature

    Science.gov (United States)

    Vikegard, Peter; Barros, Nieves; Piñeiro, Verónica

    2014-05-01

    Traditionally, studies of soil biodegradation are based on CO2 dissipation rates. CO2 is a product of aerobic degradation of labile organic substrates like carbohydrates. That limits the biodegradation concept to just one of the soil organic matter fractions. This feature is responsible for some problems to settle the concept of soil organic matter (SOM) recalcitrance and for controversial results defining sensitivity of SOM to temperature. SOM consists of highly complex macromolecules constituted by fractions with different chemical nature and redox state affecting the chemical nature of biodegradation processes. Biodegradation of fractions more reduced than carbohydrates take place through metabolic pathways that dissipate less CO2 than carbohydrate respiration, that may not dissipate CO2, or that even may uptake CO2. These compounds can be considered more recalcitrant and with lower turnover times than labile SOM just because they are degraded at lower CO2 rates that may be just a consequence of the metabolic path. Nevertheless, decomposition of every kind of organic substrate always releases heat. For this reason, the measurement of the heat rate by calorimetry yields a more realistic measurement of the biodegradation of the SOM continuum. TAM III is one of the most recent calorimeters designed for directly measuring in real time the heat rate associated with any degradation process. It is designed as a multichannel system allowing the concomitant measurement of to up 24 samples at isothermal conditions or through a temperature scanning mode from 18 to 100ºC, allowing the continous measure of any sample at controlled non-isothermal conditions. The temperature scanning mode was tested in several soil samples collected at different depths to study their sensitivity to temperature changes from 18 to 35 ºC calculating the Q10 and the activation energy (EA) by the Arrhenius equation. It was attempted to associate the obtained EA values with the soil thermal

  2. COP-compost: a software to study the degradation of organic pollutants in composts.

    Science.gov (United States)

    Zhang, Y; Lashermes, G; Houot, S; Zhu, Y-G; Barriuso, E; Garnier, P

    2014-02-01

    Composting has been demonstrated to be effective in degrading organic pollutants (OP) whose behaviour depends on the composting conditions, the microbial populations activated and interactions with organic matters. The fate of OP during composting involves complex mechanisms and models can be helpful tools for educational and scientific purposes, as well as for industrialists who want to optimise the composting process for OP elimination. A COP-Compost model, which couples an organic carbon (OC) module and an organic pollutant (OP) module and which simulates the changes of organic matter, organic pollutants and the microbial activities during the composting process, has been proposed and calibrated for a first set of OP in a previous study. The objectives of the present work were (1) to introduce the COP-Compost model from its convenient interface to a potential panel of users, (2) to show the variety of OP that could be simulated, including the possibility of choosing between degradation through co-metabolism or specific metabolism and (3) to show the effect of the initial characteristics of organic matter quality and its microbial biomass on the simulated results of the OP dynamic. In the model, we assumed that the pollutants can be adsorbed on organic matter according to the biochemical quality of the OC and that the microorganisms can degrade the pollutants at the same time as they degrade OC (by co-metabolism). A composting experiment describing two different (14)C-labelled organic pollutants, simazine and pyrene, were chosen from the literature because the four OP fractions simulated in the model were measured during the study (the mineralised, soluble, sorbed and non-extractable fractions). Except for the mineralised fraction of simazine, a good agreement was achieved between the simulated and experimental results describing the evolution of the different organic fractions. For simazine, a specific biomass had to be added. To assess the relative importance

  3. Photo-catalytic degradation of surfactants hexadecyltrimethyl-ammonium chloride in aqueous medium - a kinetic study

    International Nuclear Information System (INIS)

    Soomro, S.A.; Aziz, S.; Memon, A.R.

    2011-01-01

    Surfactants in the environment are a prerequisite for the sustainable development of human health and ecosystems. Surfactants are important in daily life in households as well as in industrial cleansing processes. It is important to have a detailed knowledge about their lifetime in the environment, their biodegradability in wastewater treatment plants and in natural waters, and their eco toxicity. Most of the issues on environmental acceptability focus on the effects on the environment associated with the use and disposal of these surfactants. These effects are taken into account by a risk assessment. The first step in a risk assessment is to estimate the concentrations of surfactants in the environmental compartment of interest, such as wastewater treatment plant effluents, surface waters, sediments, and soils. This estimate is generated either by actual measurement or by prediction via modelling. The measured or predicted concentrations are then compared to the concentrations of surfactant known to be toxic to organisms living in these environmental compartments. There are many situations where industry is producing both heavy metals ions and organic pollutants. Successful treatment of effluents of this type to achieve legislative compliance will depend on whether the heavy metals effect the process of degradation of the organic species and whether the presence of organic molecules hinder the process of removal of heavy metals. Degradation of cationic surfactant was studied with a photolytic cell system. Compressed air was used as oxidant and the temperature was maintained at 25-30 deg. C. Effect of UV source, hydrogen peroxide (H/sub 2/O/sub 2/) and titanium (TiO/sub 2/) on Hexadecyltrimethyl-ammonium chloride (C/sub 19/H/sub 42/NCl) were recorded. HPLC and IR were used to analyse the rate of degradation of Hexadecyltrimethyl-ammonium chloride (C/sub 19/H/sub 42/NCl).

  4. Managing aging workers: a mixed methods study on bundles of HR practices for aging workers

    NARCIS (Netherlands)

    Kooij, Dorien T. A. M.; Jansen, Paul G. W.; Dikkers, Josje S. E.; de Lange, Annet H.

    2014-01-01

    Since abilities and motives change with age and common human resource (HR) practices might be less suitable for aging employees, scholars and practitioners are currently challenged to find new ways of managing aging workers and motivating them to continue working. Therefore, this mixed methods study

  5. Late Bronze Age hoard studied by PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez Neira, P.C., E-mail: carolina.gutierrez@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Zucchiatti, A., E-mail: alessandro.zucchiatti@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Montero-Ruiz, I., E-mail: ignacio.montero@cchs.csic.es [CCHS-CSIC, Albasanz 26-28, E 28037 Madrid (Spain); Vilaca, R., E-mail: rvilaca@fl.uc.pt [University of Coimbra, Largo da Porta Ferrea, 3000-447 Coimbra (Portugal); Bottaini, C., E-mail: keret18@yahoo.it [University of Coimbra, Largo da Porta Ferrea, 3000-447 Coimbra (Portugal); Gener, M., E-mail: marc.gener@cchs.csic.es [CCHS-CSIC, Albasanz 26-28, E 28037 Madrid (Spain); Climent-Font, A., E-mail: acf@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Department of Applied Physics, Universidad Autonoma de Madrid, Campus Cantobalanco, E-28049 Madrid (Spain)

    2011-12-15

    The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising four socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni, and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production.

  6. Study of ageing effects in aerogel

    International Nuclear Information System (INIS)

    Bellunato, T.; Calvi, M.; Coluzza, C.; Longo, G.; Matteuzzi, C.; Musy, M.; Negri, P.; Perego, D.L.

    2004-01-01

    Ageing effects on aerogel due to irradiation and absorption of humidity have been investigated. Aerogel tiles have been exposed to γ radiation from a 60 Co source and to proton and neutron high intensity beams. The transmittance has been monitored in the wavelength range between 200 and 800 nm, determining the clarity factor C as a function of the increasing dose of irradiation. The index of refraction n was also measured

  7. Study of ageing effects in aerogel

    CERN Document Server

    Bellunato, T F; Coluzza, C; Longo, G; Matteuzzi, C; Musy, M; Negri, P; Perego, D L

    2004-01-01

    Ageing effects on aerogel due to irradiation and absorption of humidity have been investigated. Aerogel tiles have been exposed to gamma radiation from a 60-Co source and to proton and neutron high intensity beams. The transmittance has been monitored in the wavelength range between 200 nm and 800 nm, determining the clarity factor C as a function of the increasing dose of irradiation. The index of refraction n was also measured.

  8. [Simulated study of algal fatty acid degradation in hypoxia seawater-sediment interface along China coastal area].

    Science.gov (United States)

    Sui, Wei-Wei; Ding, Hai-Bing; Yang, Gui-Peng; Lu, Xiao-Lan; Li, Wen-Juan; Sun, Li-Qun

    2013-11-01

    Series of laboratory incubation experiments were conducted to simulate degradation of organic matter in sediment-seawater interface in hypoxia enviroments along China coastal area. Under four different redox conditions (oxygen saturation: 100%, 50%, 25% and 0%), degradations of seveal biomarkers originated from Skeletonema costatum, a typical red tide alage along China coastal area were tracked. By analyzing concentrations of four fatty acid biomarkers [14:0, 16:0, 16:1(7) and 20:5] obtained at various sampling time, results showed that their concentrations decreased significantly after 2-3 weeks' incubation. Then, their concentrations changed very slowly or very little. However, degradation of the four fatty acids varied dramatically in different incubation systems. Fatty acids 14:0, 16:1(7) and 20:5 were degraded completely in all incubation systems after two-month incubation, but 25% to 35% of 16:0 was reserved in the systems. Based on multi-G model, degradations of the four fatty acids were quantively described. The results indicated that all four fatty acids had fast-degraded and slow-degraded fractions. Their degradation rate constants (k(av)) ranged from 0.079 to 0.84 d(-1). The fastest degradation of 14:0 and 16:1 (7) occurred under 25% oxygen concentrations. For these two compounds, in the fastest degradation system, their k(av), values were 2.3 folds and 1.7 folds higher than those in the slowest degradation system [50% oxygen saturation for 14:0 and 100% oxygen saturation for 16:1(7)] respectively. The 16:0 was degraded fastest under the anoxic condition and slowest under the 50% oxygen saturation. The ratio of the two k(av)s was 2.1. The k(av)s of 20:5 had a positive relationship with oxygen saturations. Results of this study suggested that besides oxgen saturations, structure and features of organic compounds, roles of microbe in the envrioments and etc. might affect degradations of fatty acids in S. costatum in hypoxia sediment-seawater interface

  9. Photo-assisted Fenton type processes for the degradation of phenol: A kinetic study

    International Nuclear Information System (INIS)

    Kusic, Hrvoje; Koprivanac, Natalija; Bozic, Ana Loncaric; Selanec, Iva

    2006-01-01

    In this study the application of advanced oxidation processes (AOPs), dark Fenton and photo-assisted Fenton type processes; Fe 2+ /H 2 O 2 , Fe 3+ /H 2 O 2 , Fe 0 /H 2 O 2 , UV/Fe 2+ /H 2 O 2 , UV/Fe 3+ /H 2 O 2 and UV/Fe 0 /H 2 O 2 , for degradation of phenol as a model organic pollutant in the wastewater was investigated. A detail kinetic modeling which describes the degradation of phenol was performed. Mathematical models which predict phenol decomposition and formation of primary oxidation by-products: catechol, hydroquinone and benzoquinone, by applied processes were developed. The study also consist the modeling of mineralization kinetic of the phenol solution by applied AOPs. This part, besides well known reactions of Fenton and photo-Fenton chemistry, involves additional reactions which describe removal of iron from catalytic cycle through formation of ferric complexes and its regeneration induced by UV radiation. Phenol decomposition kinetic was monitored by HPLC analysis and total organic carbon content measurements (TOC). Complete phenol removal was obtained by all applied processes. Residual TOC by applied Fenton type processes ranged between 60.2 and 44.7%, while the efficiency of those processes was significantly enhanced in the presence of UV light, where residual TOC ranged between 15.2 and 2.4%

  10. Gold nanoworms immobilized graphene oxide polymer brush nanohybrid for catalytic degradation studies of organic dyes

    International Nuclear Information System (INIS)

    Mogha, Navin Kumar; Gosain, Saransh; Masram, Dhanraj T.

    2017-01-01

    Highlights: • AuNPs on PDMAEMA brushes immobilized reduced graphene oxide was used as catalyst. • A novel highly efficient, reusable heterogeneous catalyst for dyes degradation. • Rhodamine B, Methyl Orange and Eosin Y was used for study. • Apparent rate constant observed was 21.8, 26.2, and 8.7 (×10 −3 s −1 ) respectively. - Abstract: In the present work, we report gold nanoparticles (AuNPs) on poly (dimethylaminoethyl methacrylate) (PDMAEMA) brushes immobilized reduced graphene oxide (Au/PDMAEMA/RGO) as catalyst for degradation kinetic studies of Rhodamine B (RB), Methyl Orange (MO) and Eosine Y (EY) dyes, having an excellent catalytic activity, as evident by the apparent rate constant (k app ), which is found to be 21.8, 26.2, and 8.7 (×10 −3 s −1 ), for RB, MO and EY respectively. Au/PDMAEMA/RGO catalyst is easy to use, highly efficient, recyclable, which make it suitable for applications in waste water management. Foremost, synthesis of PDMAEMA brushes on graphene oxide is accomplished by Atom transfer radical polymerization method (ATRP), whereas AuNPs are synthesized by simple chemical reduction method.

  11. Environmental degradation and migration: the U.S.-Mexico case study.

    Science.gov (United States)

    1998-01-01

    This article provides a detailed account of the conclusions and policy recommendations of a study of environmental degradation and migration between the US and Mexico. Key recommendations and findings were included in the official US Congressional Commission on Immigration Reform report (September 1997). The Congressional report urges Congress to consider environment and development root causes of migration in establishing foreign policies with Mexico and other countries. It appears that the root cause of Mexican migration is rural land degradation or desertification. The study suggests feasible solutions, and not additional border security and employment-related sanctions. The US has the technology and expertise to facilitate programs that address environmental and development issues in targeted and integrated ways. The recommendations serve as a framework for policy reform and debate on rural development and agricultural productivity. Mexican states should be targeted that are new migration-sending states with extensive poverty and soil erosion problems and well-established migration states. Environment, population, and migration are all housed in the Global Affairs Office in the US Department of State, but there is little program integration. The USAID bureaucracy separates agricultural and environmental programs. Solutions include, for example, reducing the costs of remittances from the US to Mexico, conducting research on integrated solutions, and contributing to improved land and water management practices, forest management and land tenure, and the competitiveness of smallholders.

  12. Study of distillation and degradation of perfluoro polyether; Estudo da destilacao e degradacao do perfluoropolieter

    Energy Technology Data Exchange (ETDEWEB)

    Lopergolo, Lilian Cristine

    1997-07-01

    Perfluoro-polyethers, PFPE, were first synthesised by Sianesi and collaborators giving rise to a new lubricant oils and greases classes with several applications. Perfluoro polyethers have excellent properties, for instance: high chemical stability and thermal stability, high density, high radiation resistance and excellent lubricating properties. FOMBLIN-Y oil is one of the perfluoro polyethers used as a lubricant in vacuum systems applied in the UF{sub 6} enrichment installations. Due to its excellent properties and for its applications in the nuclear field, IPEN-CNEN/S P had the interest to dominate its production technology with the aim to substitute the commercial FOMBLIN-Y oil used in the national consumption. The FOMBLIN-Y oil synthesis method, adopted in IPEN-CNEN/S P, made by the photooxidation of the hexa fluoro propylene. In this work we study the fraction separation of the national available production with restricted an increased molecular weights which was obtained by fraction distillation in a vacuum according to the ASTM D-1160 norm. We also study the catalytic effect of metals on the thermal stability of perfluoro polyethers. The inertness of perfluoro polyethers at temperatures higher than 300 deg C is strongly affected by presence of some metals. Al and Ti alloys cause fluid degradation at 250 deg C. This degradation is very important because it has a yield increase of the perfluoro polyethers production. (author)

  13. Gold nanoworms immobilized graphene oxide polymer brush nanohybrid for catalytic degradation studies of organic dyes

    Energy Technology Data Exchange (ETDEWEB)

    Mogha, Navin Kumar; Gosain, Saransh; Masram, Dhanraj T., E-mail: dhnaraj_masram27@rediffmail.com

    2017-02-28

    Highlights: • AuNPs on PDMAEMA brushes immobilized reduced graphene oxide was used as catalyst. • A novel highly efficient, reusable heterogeneous catalyst for dyes degradation. • Rhodamine B, Methyl Orange and Eosin Y was used for study. • Apparent rate constant observed was 21.8, 26.2, and 8.7 (×10{sup −3} s{sup −1}) respectively. - Abstract: In the present work, we report gold nanoparticles (AuNPs) on poly (dimethylaminoethyl methacrylate) (PDMAEMA) brushes immobilized reduced graphene oxide (Au/PDMAEMA/RGO) as catalyst for degradation kinetic studies of Rhodamine B (RB), Methyl Orange (MO) and Eosine Y (EY) dyes, having an excellent catalytic activity, as evident by the apparent rate constant (k{sub app}), which is found to be 21.8, 26.2, and 8.7 (×10{sup −3} s{sup −1}), for RB, MO and EY respectively. Au/PDMAEMA/RGO catalyst is easy to use, highly efficient, recyclable, which make it suitable for applications in waste water management. Foremost, synthesis of PDMAEMA brushes on graphene oxide is accomplished by Atom transfer radical polymerization method (ATRP), whereas AuNPs are synthesized by simple chemical reduction method.

  14. Study of herbicide ametryne degradation in HDPE packaging using the advanced oxidation process by ionizing radiation

    International Nuclear Information System (INIS)

    Andrade, Debora Cristina de

    2008-01-01

    This study is part of the project with the objective to evaluate pesticides degradation for decontamination of commercial polymeric packaging of high density polyethylene, HDPE, used in agriculture. The herbicide used to this study was the herbicide ametryne (commercial name, Gesapax 500), due to its great use, mainly on field crops and on corn. Ametryne is commercialized since 1975, and, depending on the pesticide formulation and type of application, residues may be detectable in water, soil and on the surfaces for months or years. In order to evaluate the efficiency of radiation processing on removal the pesticides contamination, HDPE packaging were irradiated using Radiation Dynamics Electron Beam Accelerator with 1,5 MeV energy and 37 kW, in batch system. The samples were irradiated with water, in various absorbed doses. Ametryne was analyzed by gas chromatography (GC Shimadzu 17A), after extraction with hexane/dichloromethane (1:1 v/v) solution. The calibration curve was obtained with a regression coefficient of 0.986, and the relative standard deviation was lower than 10%. The radiation processing yield was evaluated by the rate of ametryne degradation and by the destruction G-value (Gd). The electron beam irradiation processing, showed high efficiency in destroying ametryne in the HDPE packaging when the samples were irradiated in presence of small quantities of water. (author)

  15. Batch growth kinetic studies of locally isolated cyanide-degrading Serratia marcescens strain AQ07.

    Science.gov (United States)

    Karamba, Kabiru Ibrahim; Ahmad, Siti Aqlima; Zulkharnain, Azham; Yasid, Nur Adeela; Ibrahim, Salihu; Shukor, Mohd Yunus

    2018-01-01

    The evaluation of degradation and growth kinetics of Serratia marcescens strain AQ07 was carried out using three half-order models at all the initial concentrations of cyanide with the values of regression exceeding 0.97. The presence of varying cyanide concentrations reveals that the growth and degradation of bacteria were affected by the increase in cyanide concentration with a total halt at 700 ppm KCN after 72 h incubation. In this study, specific growth and degradation rates were found to trail the substrate inhibition kinetics. These two rates fitted well to the kinetic models of Teissier, Luong, Aiba and Heldane, while the performance of Monod model was found to be unsatisfactory. These models were used to clarify the substrate inhibition on the bacteria growth. The analyses of these models have shown that Luong model has fitted the experimental data with the highest coefficient of determination ( R 2 ) value of 0.9794 and 0.9582 with the lowest root mean square error (RMSE) value of 0.000204 and 0.001, respectively, for the specific rate of degradation and growth. It is the only model that illustrates the maximum substrate concentration ( S m ) of 713.4 and empirical constant ( n ) of 1.516. Tessier and Aiba fitted the experimental data with a R 2 value of 0.8002 and 0.7661 with low RMSE of 0.0006, respectively, for specific biodegradation rate, while having a R 2 value of 0.9 and RMSE of 0.001, respectively, for specific growth rate. Haldane has the lowest R 2 value of 0.67 and 0.78 for specific biodegradation and growth rate with RMSE of 0.0006 and 0.002, respectively. This indicates the level of the bacteria stability in varying concentrations of cyanide and the maximum cyanide concentration it can tolerate within a specific time period. The biokinetic constant predicted from this model demonstrates a good ability of the locally isolated bacteria in cyanide remediation in industrial effluents.

  16. The impact of land use/land cover changes on land degradation dynamics: a Mediterranean case study.

    Science.gov (United States)

    Bajocco, S; De Angelis, A; Perini, L; Ferrara, A; Salvati, L

    2012-05-01

    In the last decades, due to climate changes, soil deterioration, and Land Use/Land Cover Changes (LULCCs), land degradation risk has become one of the most important ecological issues at the global level. Land degradation involves two interlocking systems: the natural ecosystem and the socio-economic system. The complexity of land degradation processes should be addressed using a multidisciplinary approach. Therefore, the aim of this work is to assess diachronically land degradation dynamics under changing land covers. This paper analyzes LULCCs and the parallel increase in the level of land sensitivity to degradation along the coastal belt of Sardinia (Italy), a typical Mediterranean region where human pressure affects the landscape characteristics through fires, intensive agricultural practices, land abandonment, urban sprawl, and tourism concentration. Results reveal that two factors mainly affect the level of land sensitivity to degradation in the study area: (i) land abandonment and (ii) unsustainable use of rural and peri-urban areas. Taken together, these factors represent the primary cause of the LULCCs observed in coastal Sardinia. By linking the structural features of the Mediterranean landscape with its functional land degradation dynamics over time, these results contribute to orienting policies for sustainable land management in Mediterranean coastal areas.

  17. Exploration of reaction mechanisms of anthocyanin degradation in a roselle extract through kinetic studies on formulated model media.

    Science.gov (United States)

    Sinela, André Mundombe; Mertz, Christian; Achir, Nawel; Rawat, Nadirah; Vidot, Kevin; Fulcrand, Hélène; Dornier, Manuel

    2017-11-15

    Effect of oxygen, polyphenols and metals was studied on degradation of delphinidin and cyanidin 3-O-sambubioside of Hibiscus sabdariffa L. Experiments were conducted on aqueous extracts degassed or not, an isolated polyphenolic fraction and extract-like model media, allowing the impact of the different constituents to be decoupled. All solutions were stored for 2months at 37°C. Anthocyanin and their degradation compounds were regularly HPLC-DAD-analyzed. Oxygen concentration did not impact the anthocyanin degradation rate. Degradation rate of delphinidin 3-O-sambubioside increased 6-fold when mixed with iron from 1 to 13mg.kg -1 but decreased with chlorogenic and gallic acids. Degradation rate of cyanidin 3-O-sambubioside was not affected by polyphenols but increased by 3-fold with increasing iron concentration with a concomitant yield decrease of scission product, protocatechuic acid. Two pathways of degradation of anthocyanins were identified: a major metal-catalyzed oxidation followed by condensation and a minor scission which represents about 10% of degraded anthocyanins. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The Impact of Land Use/Land Cover Changes on Land Degradation Dynamics: A Mediterranean Case Study

    Science.gov (United States)

    Bajocco, S.; De Angelis, A.; Perini, L.; Ferrara, A.; Salvati, L.

    2012-05-01

    In the last decades, due to climate changes, soil deterioration, and Land Use/Land Cover Changes (LULCCs), land degradation risk has become one of the most important ecological issues at the global level. Land degradation involves two interlocking systems: the natural ecosystem and the socio-economic system. The complexity of land degradation processes should be addressed using a multidisciplinary approach. Therefore, the aim of this work is to assess diachronically land degradation dynamics under changing land covers. This paper analyzes LULCCs and the parallel increase in the level of land sensitivity to degradation along the coastal belt of Sardinia (Italy), a typical Mediterranean region where human pressure affects the landscape characteristics through fires, intensive agricultural practices, land abandonment, urban sprawl, and tourism concentration. Results reveal that two factors mainly affect the level of land sensitivity to degradation in the study area: (i) land abandonment and (ii) unsustainable use of rural and peri-urban areas. Taken together, these factors represent the primary cause of the LULCCs observed in coastal Sardinia. By linking the structural features of the Mediterranean landscape with its functional land degradation dynamics over time, these results contribute to orienting policies for sustainable land management in Mediterranean coastal areas.

  19. Clinical studies of renal morphological changes with aging

    International Nuclear Information System (INIS)

    Hosokawa, Shin-ichi; Kawamura, Juichi; Tomoyoshi, Tadao; Yoshida, Osamu

    1980-01-01

    We studied the change of renal shape due to development and aging by using sup(99m)Tc-DMSA renal scintigraphy. In pediatric age group, the angle between renal longitudinal axis and the lumbar vertebrae is small but becomes larger with aging. The renal size grows with aging in the adult age group, and becomes largest. In geriatric age group it decreases with aging. The stability of renal position is marked in the adult age group, but in the pediatric and geriatric age group it seemed unstable. Renal contour is smooth in the pediatric and adult age group but unsmooth in the geriatric. sup(99m)Tc-DMSA renal image shows diffusely homogeneous renal uptake in the pediatric and adult age groups but not homogeneous in the geriatric. (author)

  20. Factors Affecting Farmers’ Adaptation Strategies to Environmental Degradation and Climate Change Effects: A Farm Level Study in Bangladesh

    Directory of Open Access Journals (Sweden)

    Mohammed Nasir Uddin

    2014-09-01

    Full Text Available Offering a case study of coastal Bangladesh, this study examines the adaptation of agriculturalists to degrading environmental conditions likely to be caused or exacerbated under global climate change. It examines four central components: (1 the rate of self-reported adoption of adaptive mechanisms (coping strategies as a result of changes in climate; (2 ranking the potential coping strategies based on their perceived importance to agricultural enterprises; (3 identification the socio-economic factors associated with adoption of coping strategies, and (4 ranking potential constraints to adoption of coping strategies based on farmers’ reporting on the degree to which they face these constraints. As a preliminary matter, this paper also reports on the perceptions of farmers in the study about their experiences with climatic change. The research area is comprised of three villages in the coastal region (Sathkhira district, a geographic region which climate change literature has highlighted as prone to accelerated degradation. One-hundred (100 farmers participated in the project’s survey, from which the data was used to calculate weighted indexes for rankings and to perform logistic regression. The rankings, model results, and descriptive statistics, are reported here. Results showed that a majority of the farmers self-identified as having engaged in adaptive behavior. Out of 14 adaptation strategies, irrigation ranked first among farm adaptive measures, while crop insurance has ranked as least utilized. The logit model explained that out of eight factors surveyed, age, education, family size, farm size, family income, and involvement in cooperatives were significantly related to self-reported adaptation. Despite different support and technological interventions being available, lack of available water, shortage of cultivable land, and unpredictable weather ranked highest as the respondent group’s constraints to coping with environmental

  1. Kinetic Degradation and Controlled Drug Delivery System Studies for Sensitive Hydrogels Prepared by Gamma Irradiation

    International Nuclear Information System (INIS)

    Eid, M.; El-Arnaouty, M.B.

    2008-01-01

    Ternary mixtures of N-vinyle-2-pyrrolidone(NVP ), itaconic acid (IA) and gelatin (G) were gamma irradiated to prepared poly(NVP/IA/G) hydrogels. The equilibrium kinetic swelling, drug release behavior, Scan Electron Microscope (SEM) and the swelling-degradation kinetics were studied. Both the diffusion exponent and the diffusion coefficient increase with increasing content of (IA). Also, the swelling behavior of copolymer hydrogels in response to ph value of the external media was studied, it is noted that the highest swelling values at ph 4. The in vitro drug release behavior of these hydrogels was examined by quantification analysis with a UV/VIS spectrophotometers. Chlorpromazine hydrochloride was loaded into dried hydrogels to investigate the stimuli-sensitive property at the specific ph. The release studies show that the highest value of release was at ph 4 which can be used for drug delivery system

  2. Degradation and annealing studies on gamma rays irradiated COTS PPD CISs at different dose rates

    International Nuclear Information System (INIS)

    Wang, Zujun; Ma, Yingwu; Liu, Jing; Xue, Yuan; He, Baoping; Yao, Zhibin; Huang, Shaoyan; Liu, Minbo; Sheng, Jiangkun

    2016-01-01

    The degradation and annealing studies on Colbalt-60 gamma-rays irradiated commercial-off-the-shelf (COTS) pinned photodiode (PPD) CMOS image sensors (CISs) at the various dose rates are presented. The irradiation experiments of COTS PPD CISs are carried out at 0.3, 3.0 and 30.0 rad(Si)/s. The COTS PPD CISs are manufactured using a standard 0.18-μm CMOS technology with four-transistor pixel PPD architecture. The behavior of the tested CISs shows a remarkable degradation after irradiation and differs in the dose rates. The dark current, dark signal non-uniformity (DSNU), random noise, saturation output, signal to noise ratio (SNR), and dynamic range (DR) versus the total ionizing dose (TID) at the various dose rates are investigated. The tendency of dark current, DSNU, and random noise increase and saturation output, SNR, and DR to decrease at 3.0 rad(Si)/s are far greater than those at 0.3 and 30.0 rad(Si)/s. The damage mechanisms caused by TID irradiation at the various dose rates are also analyzed. The annealing tests are carried out at room temperature with unbiased conditions after irradiation.

  3. Degradation and annealing studies on gamma rays irradiated COTS PPD CISs at different dose rates

    Science.gov (United States)

    Wang, Zujun; Ma, Yingwu; Liu, Jing; Xue, Yuan; He, Baoping; Yao, Zhibin; Huang, Shaoyan; Liu, Minbo; Sheng, Jiangkun

    2016-06-01

    The degradation and annealing studies on Colbalt-60 gamma-rays irradiated commercial-off-the-shelf (COTS) pinned photodiode (PPD) CMOS image sensors (CISs) at the various dose rates are presented. The irradiation experiments of COTS PPD CISs are carried out at 0.3, 3.0 and 30.0 rad(Si)/s. The COTS PPD CISs are manufactured using a standard 0.18-μm CMOS technology with four-transistor pixel PPD architecture. The behavior of the tested CISs shows a remarkable degradation after irradiation and differs in the dose rates. The dark current, dark signal non-uniformity (DSNU), random noise, saturation output, signal to noise ratio (SNR), and dynamic range (DR) versus the total ionizing dose (TID) at the various dose rates are investigated. The tendency of dark current, DSNU, and random noise increase and saturation output, SNR, and DR to decrease at 3.0 rad(Si)/s are far greater than those at 0.3 and 30.0 rad(Si)/s. The damage mechanisms caused by TID irradiation at the various dose rates are also analyzed. The annealing tests are carried out at room temperature with unbiased conditions after irradiation.

  4. Comparative study of photocatalytic oxidation on the degradation of formaldehyde and fuzzy mathematics evaluation of filters

    Science.gov (United States)

    Yu, Huili; Zhang, Jieting

    2012-04-01

    In this study, formaldehyde, one of the major volatile organic compounds, is chosen as the target pollutant. The polytetrafluoroethylene (PTFE) filter, a low cost and commonly used material in industry, is employed as the substrate for nano TiO2 photocatalyst coating at room temperature, which has been scarcely used compared to ceramics or glass beads. Furthermore, a specific experimental set-up that is similar to actual air purification system is developed for the testing. The degradation mechanisms of photolysis reaction, adsorption and photocatalytic oxidation reaction on volatile organic compounds are present respectively. The influences of three aspects mentioned above are compared by a serial of experimental data. The high efficiency of volatile organic compounds on the degradation of formaldehyde is assured. Furthermore, the purification characteristics of three kinds of activated carbon filters and PTFE filter with nano TiO2 are evaluated with the method of fuzzy mathematics. In the end, the result shows that the filter with nano TiO2 has the optimal comprehensive performances.

  5. Solar plants, environmental degradation and local socioeconomic contexts: A case study in a Mediterranean country

    Energy Technology Data Exchange (ETDEWEB)

    Delfanti, Lavinia [University of Viterbo, Department DAFNE, Via S. Camillo De Lellis snc, I-11100, Viterbo (Italy); Colantoni, Andrea, E-mail: colantoni@unitus.it [University of Viterbo, Department DAFNE, Via S. Camillo De Lellis snc, I-11100, Viterbo (Italy); Recanatesi, Fabio [University of Viterbo, Department DAFNE, Via S. Camillo De Lellis snc, I-11100, Viterbo (Italy); Bencardino, Massimiliano [University of Salerno, Department of Political, Social and Communication Sciences, Via Giovanni Paolo II 132, I-84084 Fisciano (Italy); Sateriano, Adele [Via A. Di Tullio 40, I-00136, Rome (Italy); Zambon, Ilaria [University of Viterbo, Department DAFNE, Via S. Camillo De Lellis snc, I-11100, Viterbo (Italy); Salvati, Luca, E-mail: luca.salvati@crea.gov.it [Council for Agricultural Research and Economics (CREA-RPS), Via della Navicella 2-4, I-00184, Rome (Italy)

    2016-11-15

    Photovoltaic plants developed on rural land are becoming a common infrastructure in the Mediterranean region and may contribute, at least indirectly, to various forms of environmental degradation including landscape deterioration, land take, soil degradation and loss in traditional cropland and biodiversity. Our study illustrates a procedure estimating (i) the extension of ground-mounted photovoltaic fields at the municipal scale in Italy and (ii) inferring the socioeconomic profile of the Italian municipalities experiencing different expansion rates of ground-mounted photovoltaic fields over the last years (2007-2014). The procedure was based on diachronic information derived from official data sources integrated into a geographical decision support system. Our results indicate that the surface area of ground-mounted photovoltaic fields into rural land grew continuously in Italy between 2007 and 2014 with positive and increasing growth rates observed during 2007-2011 and positive but slightly decreasing growth rates over 2012-2014, as a result of market saturation and policies containing the diffusion of solar plants on greenfields. We found important differences in the density of ground-mounted solar plants between northern and southern Italian municipalities. We identified accessible rural municipalities in southern Italy with intermediate population density and large availability of non-urban land as the most exposed to the diffusion of solar plants on greenfields in the last decade. Our approach is a promising tool to estimate changes in the use of land driven by the expansion of photovoltaic fields into rural land.

  6. Solar plants, environmental degradation and local socioeconomic contexts: A case study in a Mediterranean country

    International Nuclear Information System (INIS)

    Delfanti, Lavinia; Colantoni, Andrea; Recanatesi, Fabio; Bencardino, Massimiliano; Sateriano, Adele; Zambon, Ilaria; Salvati, Luca

    2016-01-01

    Photovoltaic plants developed on rural land are becoming a common infrastructure in the Mediterranean region and may contribute, at least indirectly, to various forms of environmental degradation including landscape deterioration, land take, soil degradation and loss in traditional cropland and biodiversity. Our study illustrates a procedure estimating (i) the extension of ground-mounted photovoltaic fields at the municipal scale in Italy and (ii) inferring the socioeconomic profile of the Italian municipalities experiencing different expansion rates of ground-mounted photovoltaic fields over the last years (2007-2014). The procedure was based on diachronic information derived from official data sources integrated into a geographical decision support system. Our results indicate that the surface area of ground-mounted photovoltaic fields into rural land grew continuously in Italy between 2007 and 2014 with positive and increasing growth rates observed during 2007-2011 and positive but slightly decreasing growth rates over 2012-2014, as a result of market saturation and policies containing the diffusion of solar plants on greenfields. We found important differences in the density of ground-mounted solar plants between northern and southern Italian municipalities. We identified accessible rural municipalities in southern Italy with intermediate population density and large availability of non-urban land as the most exposed to the diffusion of solar plants on greenfields in the last decade. Our approach is a promising tool to estimate changes in the use of land driven by the expansion of photovoltaic fields into rural land.

  7. Studies on thermal degradation and termite resistant properties of chemically modified wood

    Energy Technology Data Exchange (ETDEWEB)

    Deka, M.; Saikia, C.N. [Council for Scientific and Industrial Research (CSIR), Regional Research Laboratory, Jorhat (India); Baruah, K.K. [Assam Agricultural University, Jorhat (India)

    2002-09-01

    A series of experiments were carried out to examine the resistant capacity of a chemically treated hard wood, Anthocephalus cadamba (Roxb) Miq. to thermal and termite degradation. The treatment with thermosetting resins viz. urea formaldehyde (UF), melamine formaldehyde (MF) and phenol formaldehyde (PF) at 31-33 levels of weight percent gain (WPG) increased the strength property i.e. modulus of rupture (MOR) by 7.50-21.02% and stiffness i.e. modulus of elasticity (MOE) by 9.50-12.18% over the untreated one with no remarkable effect on specific gravity. The treated samples were found resistant to termite attack, while the untreated one was badly damaged by termites on 12 months' exposure to a termite colony. The thermal degradations of untreated and treated wood samples were studied using thermogravimetric (TGA) and differential thermogravimetric (DTG) techniques at heating rates 20 and 30 {sup o}Cmin{sup -1} in temperature range 30-650{sup o}C. The treated wood was found to be thermally more stable than the untreated one. (author)

  8. Study of degradation on polypropylene accessories used in radiotherapy services due to interaction with gamma radiation

    International Nuclear Information System (INIS)

    Neto, Antonio R.; Azevedo, Elaine C.; Soboll, Danyel S.

    2013-01-01

    Polypropylene is a polymer used in radiotherapy services as immobilization parts and masks due to their thermoplastic properties that allow specific formats of construction and has a low cost production. However this material can present degradation over time and may hinder basic procedures as cleaning between uses of this accessory. In this study, samples of PP (polypropylene) were evaluated before and after irradiation with doses from 5 kGy to 25 kGy by infrared absorption spectrometry and contact angle analysis. The infrared spectrum showed material degradation by analyzing the peaks corresponding to the chemical bonds C-H, C-H2 and C-H3 which increased absorption to all doses when compared with the non-irradiated spectrum. The contact angle demonstrated that on the PP surface the contact angle decreased in all comparisons among samples irradiated and non-irradiated, showing a hydrophilic behavior. However, starting at 20 kGy it was observed less variation of angles when compared with lower doses. Irradiated at 25 kGy the material presented a contact angle almost identical to the non-irradiated material. (author)

  9. Force degradation of orthodontic latex elastics: An in-vivo study.

    Science.gov (United States)

    Qodcieh, Sadeq M Adel; Al-Khateeb, Susan N; Jaradat, Ziad W; Abu Alhaija, Elham S J

    2017-03-01

    Our objectives were to assess the force degradation of orthodontic latex elastics over 48 hours in vivo and to study the relationship between the amount of mouth opening and the degree of force decay. Fifty-two orthodontic patients wearing fixed appliances using Class II elastics were asked to wear premeasured-force 3/16-in heavy and medium intermaxillary elastics. The force amounts were measured and compared at different time intervals. Fifty percent of the force was lost after 3.9 hours for the medium elastics and after 4.9 hours for the heavy elastics. A continuous significant force drop in all elastics was seen at all time intervals (P elastics compared with the medium elastics in vivo at all time intervals (P degradation occurred in the first 4 to 5 hours. Because of breakage and for oral hygiene purposes, orthodontic elastics should be changed daily; otherwise, elastics can be used for 48 hours. Force decay of the elastics was correlated to the lateral distance between the maxillary canine and the mandibular first molar in occlusion. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  10. Inorganic elements and organic compounds degradation studies by gamma irradiation in used lubricating oils

    International Nuclear Information System (INIS)

    Scapin, Marcos Antonio

    2008-01-01

    The automotive lubricating oils have partial degradation of organic compounds and addition of undesirable inorganic elements, during its use. These substances classify the used lubricating oils as dangerous and highly toxic. According to global consensus, concerning the environmental conservation, the best is to perform a reuse treatment of these lubricating oils. For this purpose, the uses of an alternative and effective technology have been sought. In this work, the efficacy and technical feasibility of the advanced oxidation process (AOP), by gamma radiation, for used automotive lubricating oil treatment has been studied. Different quantities of hydrogen peroxide and water Milli-Q were added to oil samples. They were submitted to the Cobalt-60 irradiator, type Gammacell, with 100, 200 and 500 kGy absorbed doses. The inorganic analysis by X-ray fluorescence (WDXRF) showed inorganic elements removal, mainly to sulphur, calcium, iron and nickel elements at acceptable levels by environmental protection law for oils reusing. The gas chromatography (GC/MS) analysis showed that the advanced oxidation process promotes the organic compounds degradation. The main identified compounds were tridecane, 2-methyl-naphthalene, and trietilamina-tetramethyl urea, which have important industrial applications. The multivariate analysis, Cluster Analysis, showed that advanced oxidation process application is a viable and promising treatment for used lubricating oil reusing. (author)

  11. A Proteomic Study of Pectin Degrading Enzymes Secreted by Botrytis cinerea Grown in Liquid Culture

    Science.gov (United States)

    Shah, Punit; Gutierrez-Sanchez, Gerardo; Orlando, Ron; Bergmann, Carl

    2009-01-01

    Botrytis cinerea is a pathogenic filamentous fungus which infects more than 200 plant species. The enzymes secreted by B. cinerea play an important role in the successful colonization of a host plant. Some of the secreted enzymes are involved in the degradation of pectin, a major component of the plant cell wall. A total of 126 proteins secreted by B. cinerea were identified by growing the fungus on highly or partially esterified pectin, or on sucrose in liquid culture. Sixty-seven common proteins were identified in each of the growth conditions, of which 50 proteins exhibited a Signal P motif. Thirteen B. cinerea proteins with functions related to pectin degradation were identified in both pectin growth conditions, while only four were identified in sucrose. Our results indicate it is unlikely that the activation of B. cinerea from the dormant state to active infection is solely dependent on changes in the degree of esterification of the pectin component of the plant cell wall. Further, these results suggest that future studies of the B. cinerea secretome in infections of ripe and unripe fruits will provide important information that will describe the mechanisms that the fungus employs to access nutrients and decompose tissues. PMID:19526562

  12. Degradability studies of PLA nanocomposites under controlled water sorption and soil burial conditions

    Science.gov (United States)

    Norazlina, H.; Hadi, A. A.; Qurni, A. U.; Amri, M.; Mashelmie, S.; Kamal, Y.

    2018-04-01

    Polymer blended nanocomposites based on polylactic acid (PLA) were prepared via a simple melting process and investigated for its biodegradation behaviour. The treated CNTs were surface modified by using acid treatment and characterisations of composites were done by using Fourier Transform Infra-Red (FTIR) and UV-Vis. FTIR spectra and UV-Vis peak confirmed the surface modification of CNTs. The water uptake and weight loss behaviour based on CNTs and m-CNTs loading at different temperatures (25° and 45°C) were studied. It was found that the water absorption and weight loss of nanocomposites increased by the incorporation of CNTs and m-CNTs. Moisture induced degradation of composite samples was significant at elevated temperature. The addition of treated CNTs successfully reduced the water uptake and weight loss of nanocomposites due to less hydrolytic effect of water on nanocomposites. In soil burial test, the weight loss increases with addition of nanofiller. The loading of m-CNT reduced the ability of nanocomposites degradation.

  13. Device Engineering and Degradation Mechanism Study of All-Phosphorescent White Organic Light-Emitting Diodes

    Science.gov (United States)

    Xu, Lisong

    As a possible next-generation solid-state lighting source, white organic light-emitting diodes (WOLEDs) have the advantages in high power efficiency, large area and flat panel form factor applications. Phosphorescent emitters and multiple emitting layer structures are typically used in high efficiency WOLEDs. However due to the complexity of the device structure comprising a stack of multiple layers of organic thin films, ten or more organic materials are usually required, and each of the layers in the stack has to be optimized to produce the desired electrical and optical functions such that collectively a WOLED of the highest possible efficiency can be achieved. Moreover, device degradation mechanisms are still unclear for most OLED systems, especially blue phosphorescent OLEDs. Such challenges require a deep understanding of the device operating principles and materials/device degradation mechanisms. This thesis will focus on achieving high-efficiency and color-stable all-phosphorescent WOLEDs through optimization of the device structures and material compositions. The operating principles and the degradation mechanisms specific to all-phosphorescent WOLED will be studied. First, we investigated a WOLED where a blue emitter was based on a doped mix-host system with the archetypal bis(4,6-difluorophenyl-pyridinato-N,C2) picolinate iridium(III), FIrpic, as the blue dopant. In forming the WOLED, the red and green components were incorporated in a single layer adjacent to the blue layer. The WOLED efficiency and color were optimized through variations of the mixed-host compositions to control the electron-hole recombination zone and the dopant concentrations of the green-red layers to achieve a balanced white emission. Second, a WOLED structure with two separate blue layers and an ultra-thin red and green co-doped layer was studied. Through a systematic investigation of the placement of the co-doped red and green layer between the blue layers and the material

  14. A Study of Efficiency of Zero-valent Iron Nanoparticles in Degradation of Trichlorethylene from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Samaneh Dehghan

    2016-12-01

    mg/l, and contact time= 86 min. The results of kinetic studies revealed that TCE degradation by nZVI follows first-order kinetic model. Conclusion: It is conclude that zero-valent iron nanoparticles have a good efficiency in the degradation of TCE. On the other hand, separation of these nanoparticles is simple due to its magnetism properties, which can improve the use of these nanoparticles. 

  15. 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

  16. 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

  17. Detection of pump degradation

    International Nuclear Information System (INIS)

    Greene, R.H.; Casada, D.A.; Ayers, C.W.

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented

  18. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  19. Experimental and Theoretical Studies on Alkaline Degradation of Cellulose and its Impact on the Sorption of Radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Loon, L.R. van; Glaus, M A

    1998-08-01

    For more than ten years, cellulose degradation has been regarded as an important process which can adversely effect the sorption of radionuclides on cement in a radioactive waste repository. However, so far, it was not possible to quantify this effect. This study reports new experimental data on alkaline degradation of cellulose, together with a re-evaluation of old literature data. For the first time now, it becomes possible to quantitatively estimate the potential role of cellulose degradation in performance assessment studies. In the first part of this study, a literature overview of other studies on alkaline degradation of cellulose is given, together with a general discussion on the effect of organic ligands on the sorption of radionuclides. Further, an overview of the important mechanisms of alkaline degradation of cellulose and some kinetic aspects of the main reactions taking place is presented. The relevance of the processes for performance assessment is explained in detail. The discussion forms the starting-point for a detailed experimental program for evaluating the role of alkaline degradation of cellulose in performance assessment. In the second part, experimental studies on alkaline degradation are presented. Different cellulosic materials were degraded in an artificial cement pore water, representing the first stage of cement degradation. The most important degradation products ({alpha}- and {beta}-isosaccharinic acid) were characterised and the results compared with other studies. Kinetic parameters for the main reactions were measured and discussed. A good agreement was found between the measured values and values extrapolated from the literature. The solubility of the sparingly soluble Ca-salt of {alpha}-isosaccharinic acid (ISA) was studied as well as the interaction of ISA with cement. Sorption of ISA on cement can keep the ISA concentration in the pore water of a repository at a low level. The effect of pure ISA and degradation products on the

  20. Experimental and Theoretical Studies on Alkaline Degradation of Cellulose and its Impact on the Sorption of Radionuclides

    International Nuclear Information System (INIS)

    Loon, L.R. van; Glaus, M.A.

    1998-08-01

    For more than ten years, cellulose degradation has been regarded as an important process which can adversely effect the sorption of radionuclides on cement in a radioactive waste repository. However, so far, it was not possible to quantify this effect. This study reports new experimental data on alkaline degradation of cellulose, together with a re-evaluation of old literature data. For the first time now, it becomes possible to quantitatively estimate the potential role of cellulose degradation in performance assessment studies. In the first part of this study, a literature overview of other studies on alkaline degradation of cellulose is given, together with a general discussion on the effect of organic ligands on the sorption of radionuclides. Further, an overview of the important mechanisms of alkaline degradation of cellulose and some kinetic aspects of the main reactions taking place is presented. The relevance of the processes for performance assessment is explained in detail. The discussion forms the starting-point for a detailed experimental program for evaluating the role of alkaline degradation of cellulose in performance assessment. In the second part, experimental studies on alkaline degradation are presented. Different cellulosic materials were degraded in an artificial cement pore water, representing the first stage of cement degradation. The most important degradation products (α- and β-isosaccharinic acid) were characterised and the results compared with other studies. Kinetic parameters for the main reactions were measured and discussed. A good agreement was found between the measured values and values extrapolated from the literature. The solubility of the sparingly soluble Ca-salt of α-isosaccharinic acid (ISA) was studied as well as the interaction of ISA with cement. Sorption of ISA on cement can keep the ISA concentration in the pore water of a repository at a low level. The effect of pure ISA and degradation products on the sorption of

  1. SOFC LSM:YSZ cathode degradation induced by moisture: An impedance spectroscopy study

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Mogensen, Mogens Bjerg

    2011-01-01

    The cause of the degradation effect of moisture during operation of LSM cathode based SOFCs has been investigated by means of a detailed impedance characterization on LSM:YSZ composite cathode based SOFCs. Further the role of YSZ as cathode composite material was studied by measurements on SOFCs...... with a LSM:CGO composite cathode on a CGO interdiffusion barrier layer. It was found that both types of cathodes showed similar electrochemical characteristics towards the presence of moisture during operation. Upon addition and removal of moisture in the fed air the impedance study showed a change...... in the high frequency cathode arc, which is associated with the charge transport/transfer at the LSM/YSZ interface. On prolonged operation with the presence of moisture an ongoing increase in the high frequency cathode arc resulted in a permanent loss of cathode/electrolyte contact and thus increase...

  2. Laboratory studies of the degradation of chloropyrifos pesticide in soils supplemented by the fungus Phanerochaete chrysosporium

    International Nuclear Information System (INIS)

    Lopera Mesa, Margarita Maria; Penuela Mesa, Gustavo Antonio; Dominguez Gual, Maria Carolina; Mejia Zapata, Gloria Maria

    2005-01-01

    Degradation of the insecticide chloropyrifos was investigated in sterilized soil samples supplemented by the white rot basidiomycetes Phanerochaete chrysosporium. Degradation rates were measured during 21-day incubation at pesticide concentrations of 0,95, 5,3, and 9,41 μ/g. Phanerochaete chrysosporium showed ability to biodegrade the insecticide in values of 96,3%, 82,4% and 62,2%, respectively, followed by rapid degradation at low initial concentration of chloropyrifos

  3. Rubidium-strontium and uranium-lead isotopic age studies

    International Nuclear Information System (INIS)

    Loveridge, W.D.

    1981-01-01

    The results of five Rb-Sr isotopic age studies predominantly on whole-rock samples, and six U-Pb studies on zircon monazite concentrates are presented. Descriptions of the geological problems and interpretations of the measured ages are included. Laboratory age determination methods and techniques are described or referenced

  4. Lifetimes of organic photovoltaics: Design and synthesis of single oligomer molecules in order to study chemical degradation mechanisms

    DEFF Research Database (Denmark)

    Alstrup, J.; Norrman, K.; Jørgensen, M.

    2006-01-01

    Degradation mechanisms in organic and polymer photovoltaics are addressed through the study of an organic photovoltaic molecule based on a single phenylene-vinylene-type oligomer molecule. The synthesis of such a model compound with different end-groups is presented that allows for assignment...... of degradation products from different parts of the molecule. Photovoltaic devices with and without C(60) have been prepared and their characteristics under AM1.5 conditions are reported. The degradation of the active phenylene-vinylene compound in darkness and after 20h of illumination were investigated using...... a mass spectrometric technique (time-of-flight secondary ion mass spectrometry) allowing elucidation of the oxidative degradation pathways. (c) 2006 Elsevier B.V. All rights reserved....

  5. The effect of natural iron oxide and oxalic acid on the photocatalytic degradation of isoproturon: a kinetics and analytical study.

    Science.gov (United States)

    Boucheloukh, H; Remache, W; Parrino, F; Sehili, T; Mechakra, H

    2017-05-17

    The photocatalytic degradation of isoproturon, a persistent toxic herbicide, was investigated in the presence of natural iron oxide and oxalic acid and under UV irradiation. The influence of the relevant parameters such as the pH and the iron oxide and oxalic acid concentrations has been studied. The presence of natural iron oxide and oxalic acid in the system effectively allow the degradation of isoproturon, whereas the presence of t-butyl alcohol adversely affects the phototransformation of the target pollutant, thus indicating that an OH radical initiated the degradation mechanism. The degradation mechanism of isoproturon was investigated by means of GC-MS analysis. Oxidation of both the terminal N-(CH 3 ) 2 and isopropyl groups is the initial process leading to N-monodemethylated (NHCH 3 ), N-formyl (N(CH 3 )CHO), and CHCH 3 OH as the main intermediates. The substitution of the isopropyl group by an OH group is also observed as a side process.

  6. Study of the separation of fluoroquinolones using HPLC: Application to the study of their degradation by gamma radiation

    International Nuclear Information System (INIS)

    Ben Saad, Latifa

    2013-01-01

    A method of high performance liquid chromatography (HPLC) in reverse phase was developed for the separation of a mixture of five fluoroquinolones (lomefloxacin, ciprofloxacin, levofloxacin, enoxacin and enrofloxacin). The optimum operating conditions are: the wavelength of detection is fixed at 282nm DAD detector, the stationary phase consists of silica type X scratched Terra RP-18 (250mm x 4, 6 mm, 5μm) and the mobile phase consisted of acetonitrile and phosphate buffer (0.02 M) (20: 80 v: v), pH equal to flow rate of 1ml/M/Xin 3etde. This optimized method was applied to analyze the solutions of different concentrations of each fluoroquinolone (100 and 20 ppm) after irradiation with doses of gamma radiation (5 and 25 kGry). The study of the effect of such radiation on fluoroquinolones shows that with a dose of 5 kGry these radiations allow complete degradation of these active ingredients at a concentration of 20 ppm and the appearance of other degradation products. But a dose of 5 kGry is insufficient to degrade the active ingredients (100ppm).

  7. Study on scalable Coulombic degradation for estimating the lifetime of organic light-emitting devices

    International Nuclear Information System (INIS)

    Zhang Wenwen; Hou Xun; Wu Zhaoxin; Liang Shixiong; Jiao Bo; Zhang Xinwen; Wang Dawei; Chen Zhijian; Gong Qihuang

    2011-01-01

    The luminance decays of organic light-emitting diodes (OLEDs) are investigated with initial luminance of 1000 to 20 000 cd m -2 through a scalable Coulombic degradation and a stretched exponential decay. We found that the estimated lifetime by scalable Coulombic degradation deviates from the experimental results when the OLEDs work with high initial luminance. By measuring the temperature of the device during degradation, we found that the higher device temperatures will lead to instabilities of organic materials in devices, which is expected to result in the difference between the experimental results and estimation using the scalable Coulombic degradation.

  8. Study of the aging processes in polyurethane adhesives using thermal treatment and differential calorimetric, dielectric, and mechanical techniques ; 1, identifying the aging processes ; 2, quantifying the aging effect

    CERN Document Server

    Althouse, L P

    1979-01-01

    Study of the aging processes in polyurethane adhesives using thermal treatment and differential calorimetric, dielectric, and mechanical techniques ; 1, identifying the aging processes ; 2, quantifying the aging effect

  9. Study of degradation processes kinetics in ohmic contacts of resonant tunneling diodes based on nanoscale AlAs/GaAs heterostructures under influence of temperature

    Science.gov (United States)

    Makeev, M. O.; Meshkov, S. A.

    2017-07-01

    The artificial aging of resonant tunneling diodes based on nanoscale AlAs/GaAs heterostructures was conducted. As a result of the thermal influence resonant tunneling diodes IV curves degrade firstly due to ohmic contacts' degradation. To assess AlAs/GaAs resonant tunneling diodes degradation level and to predict their reliability, a functional dependence of the contact resistance of resonant tunneling diode AuGeNi ohmic contacts on time and temperature was offered.

  10. Parameter Estimation of a Reliability Model of Demand-Caused and Standby-Related Failures of Safety Components Exposed to Degradation by Demand Stress and Ageing That Undergo Imperfect Maintenance

    Directory of Open Access Journals (Sweden)

    S. Martorell

    2017-01-01

    Full Text Available One can find many reliability, availability, and maintainability (RAM models proposed in the literature. However, such models become more complex day after day, as there is an attempt to capture equipment performance in a more realistic way, such as, explicitly addressing the effect of component ageing and degradation, surveillance activities, and corrective and preventive maintenance policies. Then, there is a need to fit the best model to real data by estimating the model parameters using an appropriate tool. This problem is not easy to solve in some cases since the number of parameters is large and the available data is scarce. This paper considers two main failure models commonly adopted to represent the probability of failure on demand (PFD of safety equipment: (1 by demand-caused and (2 standby-related failures. It proposes a maximum likelihood estimation (MLE approach for parameter estimation of a reliability model of demand-caused and standby-related failures of safety components exposed to degradation by demand stress and ageing that undergo imperfect maintenance. The case study considers real failure, test, and maintenance data for a typical motor-operated valve in a nuclear power plant. The results of the parameters estimation and the adoption of the best model are discussed.

  11. Differences in physical aging measured by walking speed: evidence from the English Longitudinal Study of Ageing.

    Science.gov (United States)

    Weber, Daniela

    2016-01-28

    Physical functioning and mobility of older populations are of increasing interest when populations are aging. Lower body functioning such as walking is a fundamental part of many actions in daily life. Limitations in mobility threaten independent living as well as quality of life in old age. In this study we examine differences in physical aging and convert those differences into the everyday measure of single years of age. We use the English Longitudinal Study of Ageing, which was collected biennially between 2002 and 2012. Data on physical performance, health as well as information on economics and demographics of participants were collected. Lower body performance was assessed with two timed walks at normal pace each of 8 ft (2.4 m) of survey participants aged at least 60 years. We employed growth curve models to study differences in physical aging and followed the characteristic-based age approach to illustrate those differences in single years of age. First, we examined walking speed of about 11,700 English individuals, and identified differences in aging trajectories by sex and other characteristics (e.g. education, occupation, regional wealth). Interestingly, higher educated and non-manual workers outperformed their counterparts for both men and women. Moreover, we transformed the differences between subpopulations into single years of age to demonstrate the magnitude of those gaps, which appear particularly high at early older ages. This paper expands research on aging and physical performance. In conclusion, higher education provides an advantage in walking of up to 15 years for men and 10 years for women. Thus, enhancements in higher education have the potential to ensure better mobility and independent living in old age for a longer period.

  12. Study on performance simulation of polymer electrolyte fuel cell for preventing degradation

    International Nuclear Information System (INIS)

    Kobayashi, T; Doi, M; Fukuda, T; Hashimoto, R; Kanematsu, H; Utsumi, Y

    2013-01-01

    In the present study, the distribution of water content in the membrane of PEFC was analyzed by using a numerical simulation as well as understanding the behavior of internal moisture of PEFC. Eight parameters were selected for the simulation then 18 combinations of the parameters were allocated by design of experiments, thus the data obtained were analyzed by multiple regression analysis to understand the influence factor of operating conditions quantitatively. As a result, the influence of the operating parameters on the dryness of the membrane for the anode side and the cathode side of PEFC was quantitatively shown by using the method of the multiple regression analysis. Further it was found that the area where cerium carbonate ought to be coated for preventing the degradation without decreasing performance.

  13. Gold nanoworms immobilized graphene oxide polymer brush nanohybrid for catalytic degradation studies of organic dyes

    Science.gov (United States)

    Mogha, Navin Kumar; Gosain, Saransh; Masram, Dhanraj T.

    2017-02-01

    In the present work, we report gold nanoparticles (AuNPs) on poly (dimethylaminoethyl methacrylate) (PDMAEMA) brushes immobilized reduced graphene oxide (Au/PDMAEMA/RGO) as catalyst for degradation kinetic studies of Rhodamine B (RB), Methyl Orange (MO) and Eosine Y (EY) dyes, having an excellent catalytic activity, as evident by the apparent rate constant (kapp), which is found to be 21.8, 26.2, and 8.7 (×10-3 s-1), for RB, MO and EY respectively. Au/PDMAEMA/RGO catalyst is easy to use, highly efficient, recyclable, which make it suitable for applications in waste water management. Foremost, synthesis of PDMAEMA brushes on graphene oxide is accomplished by Atom transfer radical polymerization method (ATRP), whereas AuNPs are synthesized by simple chemical reduction method.

  14. Magnesium and its alloys as degradable biomaterials: corrosion studies using potentiodynamic and EIS electrochemical techniques

    Directory of Open Access Journals (Sweden)

    Wolf Dieter Müller

    2007-03-01

    Full Text Available Magnesium is potentially useful for orthopaedic and cardiovascular applications. However, the corrosion rate of this metal is so high that its degradation occurs before the end of the healing process. In industrial media the behaviour of several magnesium alloys have been probed to be better than magnesium performance. However, the information related to their corrosion behaviour in biological media is insufficient. The aim of this work is to study the influence of the components of organic fluids on the corrosion behaviour of Mg and AZ31 and LAE442 alloys using potentiodynamic, potentiostatic and EIS techniques. Results showed localized attack in chloride containing media. The breakdown potential decreased when chloride concentration increased. The potential range of the passivation region was extended in the presence of albumin. EIS measurements showed that the corrosion behaviour of the AZ31 was very different from that of LAE442 alloy in chloride solutions.

  15. Gas chromatographic study of degradation phenomena concerning building and cultural heritage materials

    International Nuclear Information System (INIS)

    Metaxa, E.; Agelakopoulou, T.; Bassiotis, I.; Karagianni, Ch.; Roubani-Kalantzopoulou, F.

    2009-01-01

    Air pollution influences all aspects of social and economical life nowadays. In order to investigate the impact of air pollution on materials of works of art, the method of Reversed Flow-Inverse Gas Chromatography has been selected. The presence of various atmospheric pollutants is studied on marbles, oxides-building materials and samples of authentic statues from the Greek Archaeological Museums of Kavala and of Philippi. The method leads to the determination of several physicochemical quantities and the characterization of the heterogeneous surfaces of these solids. Moreover, the influence of a second pollutant (synergistic effect) is examined. The structure, the properties and the behavior of the materials are examined by X-Ray Diffraction, Scanning Electron Microscopy and Raman Spectroscopy. Therefore, the precise measurement of the above mentioned quantities form the scientific basis for elucidation of the mechanism of the whole phenomenon of the degradation, thus providing a scientific platform to conservation procedures.

  16. Study on the radiation degradation of polyether-polyurethane induced by electron beam

    International Nuclear Information System (INIS)

    Huang Wei; Xiong Jie; Chen Xiaojun; Gao Xiaoling; Xu Yunshu; Fu Yibei

    2007-01-01

    Polyether-urethane samples were irradiated at the dose range from 10 to 2000 kGy by 2 MeV electron beams. Volatile species from the polymer degradation were analyzed quantitatively and qualitatively with GC/MS. Thermal properties and micro-phase separation of the samples were examined by TG and the morphology was studied by TEM and SEM. The results show that the irradiated polyether-polyurethane evolves CO 2 , H 2 , CH 4 and C 2 H 6 , etc. The thermal stabilities between the hard and soft segments in the irradiated samples are different. At high doses, the phase separation in the sample is predominant and the hard segment of sample is more stable. The dose rate affects the soft segment of the irradiated sample much more. (author)

  17. Radiation- and photoinduced degradation of pollutants in water. A comparative study

    International Nuclear Information System (INIS)

    Getoff, N.

    1991-01-01

    Absorption spectra and kinetics of the C radical 3 H 7 , n-C radical 4 H 9 , C 3 H 7 O radical 2 and n-C 4 H 9 O radical 2 transients are presented. Comparative studies on CH 2 Cl 2 , trans-1,2-dichloroethylene, trichloroethylene and tetra-chloroethylene in neutral aqueous solution with respect to their degradation under the influence of γ-rays and v.u.v.-light were performed. Based on the quantum energy (E = 6.71 eV hv for 184.9 nm) a ''photochemical'' G-value for Cl - was obtained which is about one order of magnitude higher than that resulting from γ-irradiation. This effect is based on the specific v.u.v.-light absorption by the substrates in addition to the photolysis of water. Probable reaction mechanisms for the radiation and photoinduced decomposition of the chlorinated hydrocarbons are presented. (author)

  18. The loss of ecosystem services due to land degradation. Integration of mechanistic and probabilistic models in an Ethiopian case study

    Science.gov (United States)

    Cerretelli, Stefania; Poggio, Laura; Gimona, Alessandro; Peressotti, Alessandro; Black, Helaina

    2017-04-01

    Land and soil degradation are widespread especially in dry and developing countries such as Ethiopia. Land degradation leads to ecosystems services (ESS) degradation, because it causes the depletion and loss of several soil functions. Ethiopia's farmland faces intense degradation due to deforestation, agricultural land expansion, land overexploitation and overgrazing. In this study we modelled the impact of physical factors on ESS degradation, in particular soil erodibility, carbon storage and nutrient retention, in the Ethiopian Great Rift Valley, northwestern of Hawassa. We used models of the Sediment retention/loss, the Nutrient Retention/loss (from the software suite InVEST) and Carbon Storage. To run the models we coupled soil local data (such as soil organic carbon, soil texture) with remote sensing data as input in the parametrization phase, e.g. to derive a land use map, to calculate the aboveground and belowground carbon, the evapotraspiration coefficient and the capacity of vegetation to retain nutrient. We then used spatialised Bayesian Belief Networks (sBBNs) predicting ecosystem services degradation on the basis of the results of the three mechanistic models. The results show i) the importance of mapping of ESS degradation taking into consideration the spatial heterogeneity and the cross-correlations between impacts ii) the fundamental role of remote sensing data in monitoring and modelling in remote, data-poor areas and iii) the important role of spatial BBNs in providing spatially explicit measures of risk and uncertainty. This approach could help decision makers to identify priority areas for intervention in order to reduce land and ecosystem services degradation.

  19. Aging Trajectories in Different Body Systems Share Common Environmental Etiology: The Healthy Aging Twin Study (HATS).

    Science.gov (United States)

    Moayyeri, Alireza; Hart, Deborah J; Snieder, Harold; Hammond, Christopher J; Spector, Timothy D; Steves, Claire J

    2016-02-01

    Little is known about the extent to which aging trajectories of different body systems share common sources of variance. We here present a large twin study investigating the trajectories of change in five systems: cardiovascular, respiratory, skeletal, morphometric, and metabolic. Longitudinal clinical data were collected on 3,508 female twins in the TwinsUK registry (complete pairs:740 monozygotic (MZ), 986 dizygotic (DZ), mean age at entry 48.9 ± 10.4, range 18-75 years; mean follow-up 10.2 ± 2.8 years, range 4-17.8 years). Panel data on multiple age-related variables were used to estimate biological ages for each individual at each time point, in linear mixed effects models. A weighted average approach was used to combine variables within predefined body system groups. Aging trajectories for each system in each individual were then constructed using linear modeling. Multivariate structural equation modeling of these aging trajectories showed low genetic effects (heritability), ranging from 2% in metabolic aging to 22% in cardiovascular aging. However, we found a significant effect of shared environmental factors on the variations in aging trajectories in cardiovascular (54%), skeletal (34%), morphometric (53%), and metabolic systems (53%). The remainder was due to environmental factors unique to each individual plus error. Multivariate Cholesky decomposition showed that among aging trajectories for various body systems there were significant and substantial correlations between the unique environmental latent factors as well as shared environmental factors. However, there was no evidence for a single common factor for aging. This study, the first of its kind in aging, suggests that diverse organ systems share non-genetic sources of variance for aging trajectories. Confirmatory studies are needed using population-based twin cohorts and alternative methods of handling missing data.

  20. Intracellular degradation of microspheres based on cross-linked dextran hydrogels or amphiphilic block copolymers: A comparative Raman microscopy study

    Science.gov (United States)

    van Manen, Henk-Jan; van Apeldoorn, Aart A; Verrijk, Ruud; van Blitterswijk, Clemens A; Otto, Cees

    2007-01-01

    Micro- and nanospheres composed of biodegradable polymers show promise as versatile devices for the controlled delivery of biopharmaceuticals. Whereas important properties such as drug release profiles, biocompatibility, and (bio)degradability have been determined for many types of biodegradable particles, information about particle degradation inside phagocytic cells is usually lacking. Here, we report the use of confocal Raman microscopy to obtain chemical information about cross-linked dextran hydrogel microspheres and amphiphilic poly(ethylene glycol)-terephthalate/poly(butylene terephthalate) (PEGT/PBT) microspheres inside RAW 264.7 macrophage phagosomes. Using quantitative Raman microspectroscopy, we show that the dextran concentration inside phagocytosed dextran microspheres decreases with cell incubation time. In contrast to dextran microspheres, we did not observe PEGT/PBT microsphere degradation after 1 week of internalization by macrophages, confirming previous studies showing that dextran microsphere degradation proceeds faster than PEGT/PBT degradation. Raman microscopy further showed the conversion of macrophages to lipid-laden foam cells upon prolonged incubation with both types of microspheres, suggesting that a cellular inflammatory response is induced by these biomaterials in cell culture. Our results exemplify the power of Raman microscopy to characterize microsphere degradation in cells and offer exciting prospects for this technique as a noninvasive, label-free optical tool in biomaterials histology and tissue engineering. PMID:17722552

  1. [Construction of a microbial consortium RXS with high degradation ability for cassava residues and studies on its fermentative characteristics].

    Science.gov (United States)

    He, Jiang; Mao, Zhong-Gui; Zhang, Qing-Hua; Zhang, Jian-Hua; Tang, Lei; Zhang, Hong-Jian

    2012-03-01

    A microbial consortium with high effective and stable cellulosic degradation ability was constructed by successive enrichment and incubation in a peptone cellulose medium using cassava residues and filter paper as carbon sources, where the inoculums were sampled from the environment filled with rotten lignocellulosic materials. The degradation ability to different cellulosic materials and change of main parameters during the degradation process of cassava residues by this consortium was investigated in this study. It was found that, this consortium can efficiently degrade filter paper, absorbent cotton, avicael, wheat-straw and cassava residues. During the degradation process of cassava residues, the key hydrolytic enzymes including cellulase, hemicellulase and pectinase showed a maximum enzyme activity of 34.4, 90.5 and 15.8 U on the second or third day, respectively. After 10 days' fermentation, the degradation ratio of cellulose, hemicellulose and lignin of cassava residues was 79.8%, 85.9% and 19.4% respectively, meanwhile the loss ratio of cassava residues reached 61.5%. Otherwise,it was found that the dominant metabolites are acetic acid, butyric acid, caproic acid and glycerol, and the highest hydrolysis ratio is obtained on the second day by monitoring SCOD, total volatile fatty acids and total sugars. The above results revealed that this consortium can effectively hydrolyze cassava residues (the waste produced during the cassava based bioethanol production) and has great potential to be utilized for the pretreatment of cassava residues for biogas fermentation.

  2. Stability studies and degradation analysis of plastic solar cell materials by FTIR spectroscopy

    NARCIS (Netherlands)

    Neugebauer, H.; Brabec, C.J.; Hummelen, J.C.; Janssen, R.A.J.; Sariciftci, N.S.

    1999-01-01

    Results of controlled degradation experiments performed with the individual components and with the actual mixture used in plastic solar cells are shown. A testing procedure for the stability and for degradation effects under illumination in controlled atmosphere using FTIR-ATR spectroscopy is

  3. Maize production and land degradation: a Portuguese agriculture field case study

    Science.gov (United States)

    Ferreira, Carla S. S.; Pato, João V.; Moreira, Pedro M.; Valério, Luís M.; Guilherme, Rosa; Casau, Fernando J.; Santos, Daniela; Keizer, Jacob J.; Ferreira, António J. D.

    2016-04-01

    While food security is a main challenge faced by human kind, intensive agriculture often leads to soil degradation which then can threaten productivity. Maize is one of the most important crops across the world, with 869 million tons produced worldwide in 2012/2013 (IGC 2015), of which 929.5 thousand tons in Portugal (INE 2014). In Portugal, maize is sown in April/May and harvest occurs generally in October. Conventional maize production requires high inputs of water and fertilizers to achieve higher yields. As Portuguese farmers are typically rather old (on average, 63 years) and typically have a low education level (INE 2014), sustainability of their land management practises is often not a principal concern. This could explain why, in 2009, only 4% of the Portuguese temporary crops were under no-tillage, why only 8% of the farmers performed soil analyses in the previous three years, and why many soils have a low organic matter content (INE 2014). Nonetheless, sustainable land management practices are generally accepted to be the key to reducing agricultural soil degradation, preventing water pollution, and assuring long-term crop production objectives and food security. Sustainable land management should therefore not only be a concern for policy makers but also for farmers, since land degradation will have negative repercussions on the productivity, thus, on their economical income. This paper aims to assess the impact of maize production on soil properties. The study focusses on an 8 ha maize field located in central Portugal, with a Mediterranean climate on a gently sloping terrain (<3%) and with a soil classified as Eutric Fluvisol. On the field, several experiments were carried out with different maize varieties as well as with different fertilizers (solid, liquid and both). Centre pivot irrigation was largely used. Data is available from 2003, and concerns crop yield, fertilization and irrigation practices, as well as soil properties assessed through

  4. Thermal and oxidative degradation studies of formulated C-ethers by gel-permeation chromatography

    Science.gov (United States)

    Jones, W. R., Jr.; Morales, W.

    1982-01-01

    Gel-permeation chromatography was used to analyze C-ether lubricant formulations from high-temperature bearing tests and from micro-oxidation tests. Three mu-styragel columns (one 500 and two 100 A) and a tetrahydrofuran mobile phase were found to adequately separate the C-ether degradation products. The micro-oxidation tests yielded degradation results qualitatively similar to those observed from the bearing tests. Micro-oxidation tests conducted in air yielded more degradation than did tests in nitrogen. No great differences were observed between the thermal-oxidative stabilities of the two C-ether formulations or between the catalytic degradation activities of silver and M-50 steel. C-ether formulation I did yield more degradation than did formulation II in 111- and 25-hour bearing tests, respectively.

  5. Land degradation due to open cast mines-a case study

    International Nuclear Information System (INIS)

    Dubey, Ashutosh; Nath, R.

    1998-01-01

    The contribution of open cast mines is increasing day by day in coal production. These open cast mines have direct and visible impacts on land surface. During mining stage, land is damaged and degraded. Excavation of coal and overburden dumping along with other infrastructural development is responsible for this damage and degradation. Impact of land degradation is observed as loss of forest cover, reduction and extinction of wildlife, reduction of agricultural land, destruction of geologic column, soil erosion, hydrological imbalance, socioeconomic problems, etc. in active mining areas. The present paper discusses the extent and impact of land degradation by open cast mining activity in Singrauli coal field. The paper also highlights the extent of land degradation particularly in one of the open cast mining projects of Singrauli coal field. It also suggests certain control measures to minimise the problem. (author)

  6. Degradation of connective tissue matrices by macrophages. III. Morphological and biochemical studies on extracellular, pericellular, and intracellular events in matrix proteolysis by macrophages in culture

    International Nuclear Information System (INIS)

    Werb, Z.; Bainton, D.F.; Jones, P.A.

    1980-01-01

    The aim of the present study was to determine the localization of macrophage-mediated degradation of matrix proteins. The sites of matrix degradation were examined ultrastructurally, and the effects of modulation of macrophage secretion, endocytosis, and activity of macrophage hydrolases on matrix degradation were monitored biochemically

  7. Farmers' Perceptions of Land Degradation and their Investments in Land Management: a Case Study in the Cental Rift Valley of Ethiopia

    NARCIS (Netherlands)

    Adimassu, Zenebe; Kessler, A.; Yirga, C.

    2013-01-01

    To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers’ perceptions of land degradation and

  8. High linear energy transfer degradation studies simulating alpha radiolysis of TRU solvent extraction processes

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Jeremy [Department of Chemical Engineering and Materials Science - University of California Irvine, 916 Engineering Tower, Irvine, CA, 92697 (United States); Miller, George [Department of Chemistry- University of California Irvine, 2046D PS II, Irvine, CA, 92697 (United States); Nilsson, Mikael [Department of Chemical Engineering and Materials Science - University of California Irvine, 916 Engineering Tower, Irvine, CA, 92697 (United States)

    2013-07-01

    of degradation of TBP and CMPO and their respective degradation products in the presence of high LET radiation are presented and discussed. These results are also compared to gamma studies performed in our lab and other gamma and alpha studies found in the literature. The possible application of this method to a variety of other solvent extraction ligands to study the effects of high LET radiation is also considered. (authors)

  9. Is There Successful Aging for Nonagenarians? The Vitality 90+ Study

    Directory of Open Access Journals (Sweden)

    Lily Nosraty

    2012-01-01

    Full Text Available Objectives. This study was designed (1 to estimate the prevalence of successful aging among nonagenarians based on six different models and (2 to investigate whether successful aging is associated with socio-demographic factors. Methods. A mailed survey was conducted with people aged 90+ in Tampere in 2010. Responses were received from 1283 people. The prevalence of successful aging was measured by six multidimensional models including physical, social, and psychological components. Age, sex, marital status, level of education, and place of living were studied as factors associated with successful aging. Results. The prevalence of successful aging varied from 1.6% to 18.3% depending on the model applied. Successful aging was more prevalent in men, and also more prevalent among community-living people. In most models, successful aging was also associated with younger age, being married, and a higher level of education. Discussion. Models which emphasize the absence of disease and activity as criteria for successful aging may not be the most relevant and applicable in oldest old. Instead, preference should be given to models that focus more on autonomy, adaptation and sense of purpose. Age-sensitive approaches would help us better understand the potential of successful aging among individuals who already have success in longevity.

  10. Degradation of microbial polyesters.

    Science.gov (United States)

    Tokiwa, Yutaka; Calabia, Buenaventurada P

    2004-08-01

    Microbial polyhydroxyalkanoates (PHAs), one of the largest groups of thermoplastic polyesters are receiving much attention as biodegradable substitutes for non-degradable plastics. Poly(D-3-hydroxybutyrate) (PHB) is the most ubiquitous and most intensively studied PHA. Microorganisms degrading these polyesters are widely distributed in various environments. Although various PHB-degrading microorganisms and PHB depolymerases have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. Distributions of PHB-degrading microorganisms, factors affecting the biodegradability of PHB, and microbial and enzymatic degradation of PHB are discussed in this review. We also propose an application of a new isolated, thermophilic PHB-degrading microorganism, Streptomyces strain MG, for producing pure monomers of PHA and useful chemicals, including D-3-hydroxycarboxylic acids such as D-3-hydroxybutyric acid, by enzymatic degradation of PHB.

  11. Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

    International Nuclear Information System (INIS)

    Chang, J.-K.; Hsu, C.-C.; Liu, S.-Y.; Wu, C.-I.; Gharib, M.; Yeh, N.-C.

    2016-01-01

    The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H_2O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.

  12. 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.

  13. Study of Aging ion exchange membranes used in separation processes

    International Nuclear Information System (INIS)

    Bellakhal, N.; Ghalloussi, R.; Dammak, L.

    2009-01-01

    Presently, the most important application of ion exchange membranes (IEM) is the electrodialysis. This technique consists of a membrane separation using a series of anion exchange membranes alternately and cations, often used for the desalination of brackish water. These membranes are confronted with problems of aging. Indeed, the more they are used more physical and chemical properties will change. A comparative study of the behavior of both EMI and new but the same treatment is carried out by measuring a magnitude transfer characteristic: ion permeability. Ionic permeability is a physical quantity can have an idea about the selectivity of the membrane towards the charged species and the p orosity o f the membrane. It is a transport of ions (cations + anions) through the membrane. Thus, determining the ion permeability is to determine the diffusion flux of a strong electrolyte through a membrane separating two compartments (one containing electrolytes and other water initially ultrapure who will gradually electrolyte through the membrane). The measurement technique used is that by conductimetric detection because of the ease of its implementation and its accuracy. Thus, the variation of the concentration of the electrolyte is continuously monitored by measuring the conductivity of the solution diluted with time. The curves s = f (t) MEA and MEC new and used varying concentration of the electrolyte membranes show that let in less waste of strong electrolyte (NaCl and HCl) than new ones. This can be explained by: - The functional sites are combined with polyvalent ions present even in trace amounts in the solution process and become inactive. The membrane loses its hydrophilic character and turns into a film almost hydrophobic. - The chemical attacks and electrodialysis operations have degraded and eliminated much of the fixed sites leading to the same effects on the hydrophilic membrane. - These two assumptions have been reinforced by the extent of exchange

  14. Effect of Sphingobium yanoikuyae B1 inoculation on bacterial community dynamics and polycyclic aromatic hydrocarbon degradation in aged and freshly PAH-contaminated soils

    International Nuclear Information System (INIS)

    Cunliffe, Michael; Kertesz, Michael A.

    2006-01-01

    Sphingobium yanoikuyae B1 is able to degrade a range of polycyclic aromatic hydrocarbons (PAHs) and as a sphingomonad belongs to one of the dominant genera found in PAH-contaminated soils. We examined the ecological effect that soil inoculation with S. yanoikuyae B1 has on the native bacterial community in three different soils: aged PAH-contaminated soil from an industrial site, compost freshly contaminated with PAHs and un-contaminated compost. Survival of S. yanoikuyae B1 was dependent on the presence of PAHs, and the strain was unable to colonize un-contaminated compost. Inoculation with S. yanoikuyae B1 did not cause extensive changes in the native bacterial community of either soil, as assessed by denaturing gel electrophoresis, but its presence led to an increase in the population level of two other species in the aged contaminated soil community and appeared to have an antagonistic affect on several members of the contaminated compost community, indicating niche competition. - Sphingobium yanoikuyae B1 does not cause major changes in the native bacterial community while colonizing PAH-contaminated soils, but some niche competition is evident

  15. Structural degradation of Thar lignite using MW1 fungal isolate: optimization studies

    Science.gov (United States)

    Haider, Rizwan; Ghauri, Muhammad A.; Jones, Elizabeth J.; Orem, William H.; SanFilipo, John R.

    2015-01-01

    Biological degradation of low-rank coals, particularly degradation mediated by fungi, can play an important role in helping us to utilize neglected lignite resources for both fuel and non-fuel applications. Fungal degradation of low-rank coals has already been investigated for the extraction of soil-conditioning agents and the substrates, which could be subjected to subsequent processing for the generation of alternative fuel options, like methane. However, to achieve an efficient degradation process, the fungal isolates must originate from an appropriate coal environment and the degradation process must be optimized. With this in mind, a representative sample from the Thar coalfield (the largest lignite resource of Pakistan) was treated with a fungal strain, MW1, which was previously isolated from a drilled core coal sample. The treatment caused the liberation of organic fractions from the structural matrix of coal. Fungal degradation was optimized, and it showed significant release of organics, with 0.1% glucose concentration and 1% coal loading ratio after an incubation time of 7 days. Analytical investigations revealed the release of complex organic moieties, pertaining to polyaromatic hydrocarbons, and it also helped in predicting structural units present within structure of coal. Such isolates, with enhanced degradation capabilities, can definitely help in exploiting the chemical-feedstock-status of coal.

  16. Systems Based Study of the Therapeutic Potential of Small Charged Molecules for the Inhibition of IL-1 Mediated Cartilage Degradation

    Science.gov (United States)

    Kar, Saptarshi; Smith, David W.; Gardiner, Bruce S.; Grodzinsky, Alan J.

    2016-01-01

    Inflammatory cytokines are key drivers of cartilage degradation in post-traumatic osteoarthritis. Cartilage degradation mediated by these inflammatory cytokines has been extensively investigated using in vitro experimental systems. Based on one such study, we have developed a computational model to quantitatively assess the impact of charged small molecules intended to inhibit IL-1 mediated cartilage degradation. We primarily focus on the simplest possible computational model of small molecular interaction with the IL-1 system—direct binding of the small molecule to the active site on the IL-1 molecule itself. We first use the model to explore the uptake and release kinetics of the small molecule inhibitor by cartilage tissue. Our results show that negatively charged small molecules are excluded from the negatively charged cartilage tissue and have uptake kinetics in the order of hours. In contrast, the positively charged small molecules are drawn into the cartilage with uptake and release timescales ranging from hours to days. Using our calibrated computational model, we subsequently explore the effect of small molecule charge and binding constant on the rate of cartilage degradation. The results from this analysis indicate that the small molecules are most effective in inhibiting cartilage degradation if they are either positively charged and/or bind strongly to IL-1α, or both. Furthermore, our results showed that the cartilage structural homeostasis can be restored by the small molecule if administered within six days following initial tissue exposure to IL-1α. We finally extended the scope of the computational model by simulating the competitive inhibition of cartilage degradation by the small molecule. Results from this model show that small molecules are more efficient in inhibiting cartilage degradation by binding directly to IL-1α rather than binding to IL-1α receptors. The results from this study can be used as a template for the design and

  17. Generic BWR-4 degraded core in-vessel study. Status report

    International Nuclear Information System (INIS)

    1984-11-01

    Original intent of this project was to produce a phenomenological study of the in-vessel degradation which occurs during the TQUX and TQUV sequences for a generic BWR-4 from the initiation of the FSAR Chapter 15 operational transient through core debris bed formation to the failure of the primary pressure boundary. Bounding calculations were to be performed for the two high pressure and low pressure non-LOCA scenarios to assess the uncertainties in the current state of knowledge regarding the source terms for containment integrity studies. Source terms as such were defined in terms of hydrogen generation, unreacted metal, and coolant inventroy, and in terms of the form, sequencing and mode of dispersal through the primary vessel boundary. Fission product release was not to be considered as part of this study. Premature termination of the project, however, led to the dicontinuation of work on an as is basis. Work on the in-core phase from the point of scram to core debris bed formation was largely completed. A preliminary scoping calculation on the debris bed phase had been initiated. This report documents the status of the study at termination

  18. Technical Viability of Battery Second Life: A Study from the Ageing Perspective

    DEFF Research Database (Denmark)

    Martinez-Laserna, Egoitz; Sarasketa-Zabala, Elixabet; Stroe, Daniel-Ioan

    2018-01-01

    of Lithium-ion (Li-ion) NMC/C battery State of Health (SOH) and ageing history over the second life performance, on two different applications: a residential demand management application and a power smoothing renewable integration application. The performance and degradation of second life batteries...... ageing history upon the second life battery performance and degradation. Thereby, proper monitoring and battery selection appears crucial to certify the technical viability of battery second life....

  19. Nuclear liquid wastes treatment: study of the reverse osmosis membranes degradation under γ irradiation

    International Nuclear Information System (INIS)

    Combernoux, Nicolas

    2015-01-01

    The treatment of nuclear liquid wastes by reverse osmosis (RO) involved issues of the water radiolysis and the membrane ageing due to γ irradiation effects. Membrane performances (permeability, strontium and cesium retention) were assessed after γ irradiation. Irradiation was carried out with an external 60 Co source in different conditions that simulated real used of the process (dose from 0.1 to 1 MGy, dose rate of 0.5 and 5 kGy.h -1 , with or without oxygen or water). Several analytical methods were performed to evaluate irradiation effects (ATR-FTIR, XPS, gas production, water soluble species released from the membrane). The methodology developed led to relevant information due to an innovative analytical protocol. Membrane performances started dropping between 0.2 and 0.5 MGy with oxygen and water (dose rate 0.5 kGy.h -1 ). This shift was linked to chains scissions inside the membrane active layer. The membrane degradation was weaker without oxygen or water or at high dose rate (5 kGy.h -1 ). Results showed that each analysis comforted each other. Membrane performances were also evaluated with three different types of liquid effluents, representing radioactive effluents from a post-disaster situation (groundwater type), disaster situation (seawater) or process water. Experiments were carried out at lab and pilot scales. Results indicated that the treatment of each effluent was possible by RO with an adequate choice of membrane and operating parameters. Finally, the time to reach an integrated dose threshold for the membrane in real conditions was estimated with the RABBI software: a dozen of days in the case of disaster situation to several years in the two other cases. (author) [fr

  20. Antioxidant capacity and light-aging study of HPMC films functionalized with natural plant extract.

    Science.gov (United States)

    Akhtar, Muhammad Javeed; Jacquot, Muriel; Jasniewski, Jordane; Jacquot, Charlotte; Imran, Muhammad; Jamshidian, Majid; Paris, Cédric; Desobry, Stéphane

    2012-08-01

    The aims of this work were to functionalize edible hydroxypropyl methylcellulose (HPMC) films with natural coloring biomolecules having antioxidant capacity and to study their photo-aging stability in the films. HPMC films containing a natural red color compound (NRC) at the level of 1, 2, 3 or 4% (v/v) were prepared by a casting method. A slight degradation of films color was observed after 20 days of continuous light exposure. The antioxidant activity of NRC incorporated films was stable during different steps of film formation and 20 days of dark storage. On the other hand, antioxidant activity of samples stored under light was significantly affected after 20 days. FTIR (Fourier Transformed Infrared) spectroscopy was used to characterize the new phenolic polymeric structures and to study the photo-degradation of films. The results showed a good polymerization phenomenon between NRC and HPMC in polymer matrix giving a natural color to the films. NRC showed an ability to protect pure HPMC films against photo-degradation. This phenomenon was directly proportional to the concentration of NRC. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Ageing studies of resistive Micromegas detectors for the HL-LHC

    CERN Document Server

    Galán, J; Ferrer-Ribas, E; Giganon, A; Giomataris, I; Herlant, S; Jeanneau, F; Peyaud, A; Schune, Ph; Alexopoulos, T; Byszewski, M; Iakovidis, G; Iengo, P; Ntekas, K; Leontsinis, S; de Oliveira, R; Tsipolitis, Y; Wotschack, J

    2013-01-01

    Resistive-anode Micromegas detectors are in development since several years, in an effort to solve the problem of sparks when working in high flux and high radiations environment like in the HL-LHC (ten times the luminosity of the LHC). They have been chosen as one of the technologies that will be part of the ATLAS New Small Wheel project (forward muon system). An ageing study is mandatory to assess their capabilities to handle the HL-LHC environment on a long-term period. A prototype has been exposed to several types of irradiations (X-rays, cold neutrons, 60 Co gammas) up to an equivalent HL-LHC time of more than five years without showing any degradation of the performances in terms of gain and energy resolution. Beam test studies took place in October 2012 to assess the tracking performances (efficiency, spatial resolution,...). Results of ageing studies and beam test performances are reported in this paper.

  2. Feasibility Study on: Reforestation of Degraded Grasslands in Indonesia as a Climate Change Mitigation Option

    Energy Technology Data Exchange (ETDEWEB)

    Dalfelt, A; Naess, L O; Sutamihardja, R T.M.; Gintings, N

    1997-12-31

    The report deals with a cooperation project between Norway and Indonesia dealing with a feasibility study on sustainable reforestation of degraded grasslands in Indonesia. Poor forest management and uncontrolled land use changes contribute a significant share anthropogenic emissions of greenhouse gases, especially CO{sub 2}, and one of many ways to reduce the CO{sub 2} emission is to encourage reforestation and better forest management. The report contains a brief overview of the issue of Imperata (alang-alang) grasslands, an outline of the present status, a discussion of potential costs and benefits associated with reforestation, and suggestions of strategies which could be applied to reach the desired goals. Case studies are presented from three locations where field work has been undertaken. The case studies provide baseline data about the sites and the imperata grasslands, experiences from earlier efforts to rehabilitate the grasslands, the common attitude to reforestation among the local communities, a discussion of the feasibility of reforestation, and finally, recommendations for the future. 142 refs., 11 figs., 15 tabs.

  3. Effect of Soil Fumigation on Degradation of Pendimethalin and Oxyfluorfen in Laboratory and Ginger Field Studies.

    Science.gov (United States)

    Huang, Bin; Li, Jun; Fang, Wensheng; Liu, Pengfei; Guo, Meixia; Yan, Dongdong; Wang, Qiuxia; Cao, Aocheng

    2016-11-23

    Herbicides are usually applied to agricultural fields following soil fumigation to provide effective weed control in high-value cash crops. However, phytotoxicity has been observed in ginger seedlings following the application of herbicides in fumigated fields. This study tested a mixture of herbicides (pendimethalin and oxyfluorfen) and several fumigant treatments in laboratory and field studies to determine their effect on the growth of ginger. The results showed that soil fumigation significantly (P oxyfluorfen was extended by an average of about 1.19 times in the field and 1.32 times in the laboratory. Moreover, the extended period of herbicide degradation in the fumigant and nonfumigant treatments significantly reduced ginger plant height, leaf number, stem diameter, and the chlorophyll content. The study concluded that applying a dose below the recommended rate of these herbicides in chloropicrin (CP) or CP + 1,3-dichloropropene fumigated ginger fields is appropriate, as application of the recommended herbicide dose in fumigated soil may be phytotoxic to ginger.

  4. Experimental study of radioactive aerosols emission during the thermal degradation of organic materials in nuclear facilities

    International Nuclear Information System (INIS)

    Fernandez, Yvette

    1993-01-01

    Radioactive products may be released during a fire in nuclear fuel cycles facilities. These products must be confined to avoid a contamination spread in the environment. It is therefore necessary to be able to predict the amount and the physico-chemical forms of radioactive material that may be airborne. The aim of this study is to determine experimentally the release of contamination aerosols in a typical fire scenario involving plutonium oxide in a glove box. Firstly, this phenomenon has been studied in a small scale test chamber where samples of polymethylmethacrylate (Plexiglas) contaminated by cerium oxide (used as a substitute for plutonium oxide) were submitted to thermal degradation (pyrolysis and combustion). The release of radioactive material is determined by the quantity of contaminant emitted, the kinetics of the release and the particle size distribution of aerosols. Secondly, the development of an experimental procedure allowed to realize large scale fires in more realistic conditions. The experimental tools developed in the course of this study allow to consider application to other scenarios. (author) [fr

  5. Feasibility Study on: Reforestation of Degraded Grasslands in Indonesia as a Climate Change Mitigation Option

    Energy Technology Data Exchange (ETDEWEB)

    Dalfelt, A.; Naess, L.O.; Sutamihardja, R.T.M.; Gintings, N.

    1996-12-31

    The report deals with a cooperation project between Norway and Indonesia dealing with a feasibility study on sustainable reforestation of degraded grasslands in Indonesia. Poor forest management and uncontrolled land use changes contribute a significant share anthropogenic emissions of greenhouse gases, especially CO{sub 2}, and one of many ways to reduce the CO{sub 2} emission is to encourage reforestation and better forest management. The report contains a brief overview of the issue of Imperata (alang-alang) grasslands, an outline of the present status, a discussion of potential costs and benefits associated with reforestation, and suggestions of strategies which could be applied to reach the desired goals. Case studies are presented from three locations where field work has been undertaken. The case studies provide baseline data about the sites and the imperata grasslands, experiences from earlier efforts to rehabilitate the grasslands, the common attitude to reforestation among the local communities, a discussion of the feasibility of reforestation, and finally, recommendations for the future. 142 refs., 11 figs., 15 tabs.

  6. Land degradation due to diapirs in Iran, case study: Hableh Rood drainage basin, east of Tehran

    Energy Technology Data Exchange (ETDEWEB)

    Zakikhani, K.; Feiznia, S

    2009-07-01

    Different geological characteristics play role in Land degradation in Iran which are: The abundance of Neogene evaporitic marly formations around and in desertic depression. These units had important role in the formation of present landforms, are saline, alkaline and erodible and degrade the quality of water resources as diffuse and widespread sources and are endless sources for sand dunes. The presence of numerous diapirs, some of which are salt domes consisting of halite. Due to diapirism, salts are now exposed at the surface of many parts of Iran and cause soil, surface and underground water and vegetation degradation as point sources. The importance of diapirism in geology of Iran has been emphasized previously. This paper intends to investigate the effect of salt domes in land degradation and propose restoration measures. (Author) 3 refs.

  7. MiniX-STR multiplex system population study in Japan and application to degraded DNA analysis.

    Science.gov (United States)

    Asamura, H; Sakai, H; Kobayashi, K; Ota, M; Fukushima, H

    2006-05-01

    We sought to evaluate a more effective system for analyzing X-chromosomal short tandem repeats (X-STRs) in highly degraded DNA. To generate smaller amplicon lengths, we designed new polymerase chain reaction (PCR) primers for DXS7423, DXS6789, DXS101, GATA31E08, DXS8378, DXS7133, DXS7424, and GATA165B12 at X-linked short tandem repeat (STR) loci, devising two miniX-multiplex PCR systems. Among 333 Japanese individuals, these X-linked loci were detected in amplification products ranging in length from 76 to 169 bp, and statistical analyses of the eight loci indicated a high usefulness for the Japanese forensic practice. Results of tests on highly degraded DNA indicated the miniX-STR multiplex strategies to be an effective system for analyzing degraded DNA. We conclude that analysis by the current miniX-STR multiplex systems offers high effectiveness for personal identification from degraded DNA samples.

  8. Experimental study of key parameters investigation in turnout crossing degradation process

    NARCIS (Netherlands)

    Liu, X.; Markine, V.L.; Shevtsov, I.; Dollevoet, R.P.B.J.

    2015-01-01

    The continuous increasing demand of public transportation capacity requires the railway network operating in tight schedule. The high transporting volumes not only aggravate the degradation of railway infrastructure but also shorten the time for maintenance. Well-arranged infrastructure maintenance

  9. Using the VS-Fast methodology for soil degradation assessment: a case study from Senegal

    NARCIS (Netherlands)

    Sonneveld, B.G.J.S.; McGarry, D.; Ndiaye, D.

    2012-01-01

    Soil degradation threatens sustainable food production and accelerates global warming. Poorer countries, whose agricultural sectors are highly dependent on their natural resource bases, are hit particularly hard by declining soil productivity. Calls for soil-quality monitoring are therefore,

  10. Oxidative degradation of 2,4-dioxohexahydro-1,3,5-triazine in aqueous medium: a radiation and photochemical study

    International Nuclear Information System (INIS)

    Joseph, J.M.; Jacob, T.A.; Manoj, V.M.; Aravindakumar, C.T.; Hari Mohan

    2000-01-01

    The kinetics and spectral nature of the intermediates resulting from the reaction of OH with 2,4-dioxohexahydro-1,3,5-triazine (DHT) have been studied by pulse radiolysis. The degradation leading to a complete disappearance of DHT induced by OH in aqueous medium was also studied using steady state radiolysis technique. The rate constant, determined by competitive kinetic methods, was 1.6 x 10 9 dm 3 mol -1 s -1 at pH 6. The complete degradation in N 2 O was observed with an absorbed dose of 7 kGy. The complete degradation in presence of ferricperchlorate using UV light was observed within 6 minute. (author)

  11. Scanning electron microscopic study of the hydrolytic degradation of poly(glycolic acid) suture

    International Nuclear Information System (INIS)

    Chu, C.C.; Campbell, N.D.

    1982-01-01

    This article reports the morphological observations on the surface changes of poly-(glycolic acid) sutures which have been exposed to various dosages of gamma irradiation (0, 2.5, 5.0, 10, 20 and 40 Mrad) and duration of immersion (0, 7, 14, 28, 48, 60, and 90 days) in a physiological saline buffer. The most important gross morphological characteristics of PGA suture hydrolytic degradation is the formation of surface cracks on the filaments. The regularity of the surface cracks increased with an increase in the gamma irradiation and the duration of hydrolysis. Surface cracks were not observed in irradiated sutures that had not been subjected to hydrolytic degradation. The arrangement of the surface cracks, their orientation on the filaments, and the direction of crack propagation provide very useful information for depicting the mechanism of hydrolytic degradation in this class of fibrous material. The microfibrillar model of fiber structure has been used as the basis for the proposed degradation mechanism of PGA in vitro. It is believed that hydrolysis occurs initially in the amorphous regions sandwiched between two crystalline zones, as tie-chain segments, free chain ends, and chain folds in these regions degrade into fragments. As degradation proceeds, the size of the fragments reaches the stage at which they can be dissolved into the buffer medium. This dissolution removes the fragments from the amorphous regions, and surface cracks appeared

  12. STUDIES ON FUNCTIONAL BACTERIA OF INDONESIAN TROPICAL FOREST PLANTS FOR BIOREHABILITATION OF DEGRADED LANDS

    Directory of Open Access Journals (Sweden)

    Irnayuli R. Sitepu

    2008-06-01

    Full Text Available Forest  degradations  have left vast amount  of damaged  and abandoned  lands in Indonesia.   In this paper, we present our approaches  in rehabilitation of adverse soils using functional  bacteria isolated from plant species of Indonesian tropical  rain forests. For these purposes,  we collected  bacteria  from various  bio-geo-climatically different forests and conducted bioassays to test these bacterial abilities in improving plant growth. Repeated seedling-based studies on Shorea spp., Alstonia scholaris, Acacia crassicarpa, and Agathis lorantifolia have revealed that many bacteria were able to promote plant growth at early stage in the nursery.  Various  plant responses towards  inoculations suggested that although  forest soils maintain  highly diverse and potent  bacteria,  it is necessary to select appropriate approaches to obtain optimum  benefits from these plant-bacteria interactions.  Our  ideas and futures  studies  for further  management  of these plant- bacteria interactions for biorehabilitation are also discussed.

  13. Degradation of phenylethylamine and tyramine by gamma radiation process and docking studies of its radiolytes

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, Monique; Souza, Stefânia Priscila de; Lima, Keila dos Santos Cople; França, Tanos Celmar Costa; Lima, Antonio Luis dos Santos, E-mail: santoslima@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Departamanto de Engenharia Quimica; Oliveira, Aline Alves [Universidade de Sao Paulo (USP), São Carlos, SP (Brazil). Instituto de Quimica; Rezende, Cláudia Moraes [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Quimica

    2014-07-01

    Biogenic amines (BA) are toxic low molecular weight organic bases with aliphatic or heterocyclic structures that can be found in several foods. The consumption of food containing large amounts of BA can result in allergic reactions, rash, vomiting, and hypertension. Besides, BA are also known as possible precursors of carcinogens. In the present study we evaluated the effect of different gamma irradiation doses on methanol and water solutions of the BA phenylethylamine and tyramine. Our best results showed that, at a dose of 5 kGy (SI unit used for measurement of absorbed dose of ionizing radiation), it was possible to reduce the content of these two BA up to 85 and 60%, respectively, suggesting that the use of the irradiation process can be an efficient tool for its degradation. Further docking studies also suggested that the radiolytes produced in the irradiation process have more affinity for the human detoxifying enzymes monoaminoxidases type A and B (MAO-A and MAO-B) being, therefore, less toxic than its precursors. (author)

  14. Study on de novo collagen biosynthesis and degradation markers of bone

    International Nuclear Information System (INIS)

    Hanna, L.S.; Matta, T.F.; Ibrahim, I.; Meky, N.H.

    2003-01-01

    This investigation was carried out to study the performance of de novo biochemical markers of serum pro collagen type-1 amino terminal extension (PINP), as a marker of collagen biosynthesis, and urinary collagen crosslink free deoxypyridinoline (DPD) as a marker of collagen degradation. Moreover, urinary calcium C Ca) and inorganic phosphorus (P), as markers of bone demineralization, in addition to urinary creatinine (Cr), to reflect status of renal function, were also studied in order to assess the activity of bone turnover in osteoporotic (OST), postmenopausal (POST), peri menopausal(PERI), premenopausal (PRE) women and also in young adult (YON) ones. The obtained results showed that urinary creatinine levels were within the normal ranges in all women even in the elderly osteoporotic and postmenopausal women. Serum PINP did not reflect osteoblastic activity. Urinary DPD proved to be a good marker in monitoring the postmenopausal bone resorption and urinary Ca was a reliable marker for bone loss in osteoporosis and bone turnover in the postmenopausal status

  15. Astaxanthin degradation and lipid oxidation of Pacific white shrimp oil: kinetics study and stability as affected by storage conditions

    Directory of Open Access Journals (Sweden)

    Sirima Takeungwongtrakul

    2016-02-01

    Full Text Available Abstract The kinetics of astaxanthin degradation and lipid oxidation in shrimp oil from hepatopancreas of Pacific white shrimp (Litopenaeus vannamei as affected by storage temperature were studied. When shrimp oil was incubated at different temperatures (4, 30, 45 and 60 °C for 16 h, the rate constants (k of astaxanthin degradation and lipid oxidation in shrimp oil increased with increasing temperatures (p < 0.05. Thus, astaxanthin degradation and lipid oxidation in shrimp oil were augmented at high temperature. When shrimp oils with different storage conditions (illumination, oxygen availability and temperature were stored for up to 40 days, astaxanthin contents in all samples decreased throughout storage (p < 0.05. All factors were able to enhance astaxanthin degradation during 40 days of storage. With increasing storage time, the progressive formation of primary and secondary oxidation products were found in all samples as evidenced by the increases in both peroxide values (PV and thiobarbituric acid reactive substances (TBARS (p < 0.05. Light, air and temperatures therefore had the marked effect on astaxanthin degradation and lipid oxidation in shrimp oils during the extended storage.

  16. Age differences in the motor control of speech: An fMRI study of healthy aging.

    Science.gov (United States)

    Tremblay, Pascale; Sato, Marc; Deschamps, Isabelle

    2017-05-01

    Healthy aging is associated with a decline in cognitive, executive, and motor processes that are concomitant with changes in brain activation patterns, particularly at high complexity levels. While speech production relies on all these processes, and is known to decline with age, the mechanisms that underlie these changes remain poorly understood, despite the importance of communication on everyday life. In this cross-sectional group study, we investigated age differences in the neuromotor control of speech production by combining behavioral and functional magnetic resonance imaging (fMRI) data. Twenty-seven healthy adults underwent fMRI while performing a speech production task consisting in the articulation of nonwords of different sequential and motor complexity. Results demonstrate strong age differences in movement time (MT), with longer and more variable MT in older adults. The fMRI results revealed extensive age differences in the relationship between BOLD signal and MT, within and outside the sensorimotor system. Moreover, age differences were also found in relation to sequential complexity within the motor and attentional systems, reflecting both compensatory and de-differentiation mechanisms. At very high complexity level (high motor complexity and high sequence complexity), age differences were found in both MT data and BOLD response, which increased in several sensorimotor and executive control areas. Together, these results suggest that aging of motor and executive control mechanisms may contribute to age differences in speech production. These findings highlight the importance of studying functionally relevant behavior such as speech to understand the mechanisms of human brain aging. Hum Brain Mapp 38:2751-2771, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  17. Study on aging embrittlement of 17-4PH martensite stainless steel at 350 degree C

    International Nuclear Information System (INIS)

    Wang Jun; Shen Baoluo

    2005-01-01

    The transformation of microstructure and hardness with the extension of aging time on the 17-4PH Martensite stainless steel at 350 degree C is studied, and the change of dynamic fracture toughness and fractography of the stainless steel for various holding time at this temperature are also studied by instrumental impact test and scanning electron microscope. The results indicate that the crack initiation energy (E i ), crack propagation energy (E p ), absorbed-in-fracture energy (E t ) and dynamic fracture toughness (K 1d ) of this type of alloy Charpy v-notch sample is decreased with the continuation of time at 350 degree C. It means that the toughness of the alloy is degraded, and the hardness of the steel is ascended when aging time is expanded and reaches the maximum at 9000 h. The fractography of this steel changes from dimple fracture into cleavage fracture and inter-granular rapture. (authors)

  18. Developments in polymer degradation - 7

    International Nuclear Information System (INIS)

    Grassie, N.

    1987-01-01

    A selection of topics which are representative of the continually expanding area of polymer degradation is presented. The aspects emphasised include the products of degradation of specific polymers, degradation by high energy radiation and mechanical forces, fire retardant studies and the special role of small radicals in degradation processes. (author)

  19. Studies on nitrile rubber degradation in zinc bromide completion fluid and its prevention by surface fluorination

    Science.gov (United States)

    Vega-Cantu, Yadira Itzel

    Poly(acrylonitrile-co-butadiene) or nitrile-butadiene rubber (NBR) is frequently used as an O-ring material in the oil extraction industry due to its excellent chemical properties and resistance to oil. However, degradation of NBR gaskets is known to occur during the well completion and oil extraction process where packers are exposed to completion fluids such as ZnBr2 brine. Under these conditions NBR exhibits accelerated chemical degradation resulting in embrittlement and cracking. Samples of NBR, poly(acrylonitrile) (PAN) and poly(butadiene) (PB) have been exposed to ZnBr2 based completion fluid, and analyzed by ATR and diffuse reflectance IR. Analysis shows the ZnBr2 based completion fluid promotes hydrolysis of the nitrile group to form amides and carboxylic groups. Analysis also shows that carbon-carbon double bonds in NBR are unaffected after short exposure to zinc bromide based completion fluid, but are quickly hydrolyzed in acidic bromide mixtures. Although fluoropolymers have excellent chemical resistance, their strength is less than nitrile rubber and replacing the usual gasket materials with fluoroelastomers is expensive. However, a fluoropolymer surface on a nitrile elastomer can provide the needed chemical resistance while retaining their strength. In this study, we have shown that this can be achieved by direct fluorination, a rather easy and inexpensive process. Samples of NBR O-rings have been fluorinated by exposure to F2 and F2/HF mixtures at various temperatures. Fluorination with F 2 produces the desired fluoropolymer layer; however, fluorination by F2/HF mixtures gave a smoother fluorinated layer at lower temperatures and shorter times. Fluorinated samples were exposed to ZnBr2 drilling fluid and solvents. Elemental analysis shows that the fluorinated layer eliminates ZnBr2 diffusion into the NBR polymeric matrix. It was also found that surface fluorination significantly retards the loss of mechanical properties such as elasticity, tensile

  20. Culture & differentiation of mesenchymal stem cell into osteoblast on degradable biomedical composite scaffold: In vitro study

    Directory of Open Access Journals (Sweden)

    Krishan G Jain

    2015-01-01

    Full Text Available Background & objectives: There is a significant bone tissue loss in patients from diseases and traumatic injury. The current autograft transplantation gold standard treatment has drawbacks, namely donor site morbidity and limited supply. The field of tissue engineering has emerged with a goal to provide alternative sources for transplantations to bridge this gap between the need and lack of bone graft. The aim of this study was to prepare biocomposite scaffolds based on chitosan (CHT, polycaprolactone (PCL and hydroxyapatite (HAP by freeze drying method and to assess the role of scaffolds in spatial organization, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs in vitro, in order to achieve bone graft substitutes with improved physical-chemical and biological properties. Methods: Pure chitosan (100CHT and composites (40CHT/HAP, 30CHT/HAP/PCL and 25CHT/HAP/PCL scaffolds containing 40, 30, 25 parts per hundred resin (phr filler, respectively in acetic acid were freeze dried and the porous foams were studied for physicochemical and in vitro biological properties. Results: Scanning electron microscope (SEM images of the scaffolds showed porous microstructure (20-300 μm with uniform pore distribution in all compositions. Materials were tested under compressive load in wet condition (using phosphate buffered saline at pH 7.4. The in vitro studies showed that all the scaffold compositions supported mesenchymal stem cell attachment, proliferation and differentiation as visible from SEM images, [3-(4,5-dimethylthiazole-2-yl-2,5-diphenyltetrazolium bromide] (MTT assay, alkaline phosphatase (ALP assay and quantitative reverse transcription (qRT-PCR. Interpretation & conclusions: Scaffold composition 25CHT/HAP/PCL showed better biomechanical and osteoinductive properties as evident by mechanical test and alkaline phosphatase activity and osteoblast specific gene expression studies. This study suggests that this novel

  1. A study of dissipation, degradation and binding of 14C-labeled endosulfan to soil in model lysimeter

    International Nuclear Information System (INIS)

    Gonzalez, J.E.; Ceballos, J.; Amor, A.; Saiz, E.B. de

    1999-01-01

    The degradation, dissipation and binding of α-endosulfan in two agricultural soils and sand was studied in lysimeter system under outdoor conditions, using 14 C labeled insecticide. Dissipation was rapid during the first few weeks after application. The half life of disappearance was 38 to 61 days for the soils from Cerro Punta and El Ejido, whereas, in sand it was 91 days. The insecticide degraded by oxidation at the sulfite group to the sulfate. The resultant product underwent further degradation to form 14 CO 2 and bound residues. Although a significant amount of 14 C leached through the sand, which contained less that 0.1% organic matter, there was no leaching of endosulfan through the other two types of soil, when leaching was started immediately after treatment. (author)

  2. Studies on the Conditioning Methods of Spent Tri-butyl Phosphate/Kerosene and its Degradation Product in Different Matrices

    International Nuclear Information System (INIS)

    El-Dessouky, M.I.; El-sourougy, M.R.; Abed El-Aziz, M.M.; Aly, H.F.

    1999-01-01

    The destruction of spent TBP/Kerosene (odourless Kerosene (OK)) with potassium permanganate have been investigated. Comparative studies on the immobilization of spent TBP/Kerosene and its degradation product into different matrices have been carried out. The matrices used include, ordinary Portland cement, silica fume, treated fly ash, epoxy resin and cement mixed with epoxy resin.The different factors affecting solidified waste forms such as, compressive strength, water resistance, thermal stability, chemical resistance, radiological stability and leachability have been investigated. It was found that, epoxy resin and cement mixed with 5,10,20, and 50% of epoxy resin enhance the compressive strength of the solidified waste forms with spent TBP/OK more than that obtained from degradation products. The leaching rates of 152 and 154 Eu and 181 Hf from waste forms containing TBP/OK was found lower than that with degradation product

  3. Transport and degradation of pesticides in a biopurification system under variable flux, part I: A microcosm study

    Energy Technology Data Exchange (ETDEWEB)

    De Wilde, Tineke, E-mail: dewilde.tineke@gmail.co [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Spanoghe, Pieter [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Ryckeboer, Jaak [Division Soil and Water Management, Faculty of Bioscience Engineering, Catholic University Leuven, Kasteelpark Arenberg 20, B-3001 Leuven (Belgium); Jaeken, Peter [PCF-Royal Research Station of Gorsem, De Brede Akker 13, 3800 Sint-Truiden (Belgium); Springael, Dirk [Division Soil and Water Management, Faculty of Bioscience Engineering, Catholic University Leuven, Kasteelpark Arenberg 20, B-3001 Leuven (Belgium)

    2010-10-15

    The efficiency of a biopurification system, developed to treat pesticide contaminated water, is to a large extent determined by the chemical and hydraulic load. Insight into the behaviour of pesticides under different fluxes is necessary. The behaviour of metalaxyl, bentazone, linuron, isoproturon and metamitron was studied under three different fluxes with or without the presence of pesticide-primed soil in column experiments. Due to the time-dependent sorption process, retention of the pesticides with intermediate mobility was significantly influenced by the flux. The higher the flux, the slower pesticides will be sorbed, which resulted in a lower retention. Degradation of the intermediate mobile pesticides was also submissive to variations in flux. An increase in flux, led to a decrease in retention, which in turn decreased the opportunity time for biodegradation. Finally, the presence of pesticide-primed soil was only beneficial for the degradation of metalaxyl. - Retention and degradation of pesticides in microcosms liable to different fluxes.

  4. Analysis for the Effects of Grid Voltage Degradation on APR1400 Operation, Case Study for Egypt

    International Nuclear Information System (INIS)

    Hassan, Mostafa Ahmed Fouad; Koo, Chang Choong

    2015-01-01

    Egypt is one of the countries planning to introduce a NPP into its electrical power system. Although the Egyptian power system has sufficient capacity to integrate any commercially available nuclear unit as the total installed capacity of the power system is more than 32GWe, which is more than 10 times capacity of any nuclear unit in the range of 1000 to 1700MWe, the system is vulnerable to extreme voltage variations, especially voltage degradation during peak load conditions. These conditions can lead to voltage collapse if a counter measure, usually load shedding, is not taken in a proper time. Hence, it is necessary to analyze the effect of such conditions on the safe and economic operation of the NPP. In this paper we analyzed the effects of grid voltage degradation on the safe and economic operation of the Advanced Power Reactor (APR1400) to determine any adverse effects on the plant auxiliary loads while operating in the Egyptian power system. In this paper the effects of grid voltage degradation on the safe and economic operation of APR1400 were investigated taking into account, generator operating limits, plant safety requirements, operation modes and loading categories in order to determine any adverse effect on the plant auxiliary loads while operating in the Egyptian power system. The results of the load flow and motor starting analysis demonstrated that during normal operation the automatic voltage regulator and transformers OLTCs can mitigate the effect of grid voltage degradation without any detrimental effect on the plant auxiliary loads. During the highly unlikely LOCA condition if the grid voltage degraded below 95%, the degraded voltage relays at Class 1E 4.16 kV buses will trip the supply and load breakers and reconnect the required safety loads to the EDG after 4 minutes time delay. During this period the safety loads required for LOCA can be started and accelerated to their rated speed safely even in the worst case of expected degraded voltage

  5. Age and fecundability in a North American preconception cohort study.

    Science.gov (United States)

    Wesselink, Amelia K; Rothman, Kenneth J; Hatch, Elizabeth E; Mikkelsen, Ellen M; Sørensen, Henrik T; Wise, Lauren A

    2017-12-01

    There is a well-documented decline in fertility treatment success with increasing female age; however, there are few preconception cohort studies that have examined female age and natural fertility. In addition, data on male age and fertility are inconsistent. Given the increasing number of couples who are attempting conception at older ages, a more detailed characterization of age-related fecundability in the general population is of great clinical utility. The purpose of this study was to examine the association between female and male age with fecundability. We conducted a web-based preconception cohort study of pregnancy planners from the United States and Canada. Participants were enrolled between June 2013 and July 2017. Eligible participants were 21-45 years old (female) or ≥21 years old (male) and had not been using fertility treatments. Couples were followed until pregnancy or for up to 12 menstrual cycles. We analyzed data from 2962 couples who had been trying to conceive for ≤3 cycles at study entry and reported no history of infertility. We used life-table methods to estimate the unadjusted cumulative pregnancy proportion at 6 and 12 cycles by female and male age. We used proportional probabilities regression models to estimate fecundability ratios, the per-cycle probability of conception for each age category relative to the referent (21-24 years old), and 95% confidence intervals. Among female patients, the unadjusted cumulative pregnancy proportion at 6 cycles of attempt time ranged from 62.0% (age 28-30 years) to 27.6% (age 40-45 years); the cumulative pregnancy proportion at 12 cycles of attempt time ranged from 79.3% (age 25-27 years old) to 55.5% (age 40-45 years old). Similar patterns were observed among male patients, although differences between age groups were smaller. After adjusting for potential confounders, we observed a nearly monotonic decline in fecundability with increasing female age, with the exception of 28-33 years, at which

  6. Contribution to the study of particle resuspension kinetics during thermal degradation of polymers.

    Science.gov (United States)

    Ouf, F-X; Delcour, S; Azema, N; Coppalle, A; Ferry, L; Gensdarmes, F; Lopez-Cuesta, J-M; Niang, A; Pontreau, S; Yon, J

    2013-04-15

    Experimental results are reported on the resuspension of particles deposited on polymer samples representative of glove boxes used in the nuclear industry, under thermal degradation. A parametric study was carried out on the effects of heat flux, air flow rate, fuel type and particle size distribution. Small-scale experiments were conducted on 10 cm × 10 cm PolyMethyl MethAcrylate (PMMA) and PolyCarbonate (PC) samples covered with aluminium oxide particles with physical geometric diameters of 0.7 and 3.6 μm. It was observed for both polymer (fuel) samples that heat flux has no effect on the airborne release fraction (ARF), whereas particle size is a significant parameter. In the case of the PMMA sample, ARF values for 0.7 and 3.6 μm diameter particles range from 12.2% (± 6.2%) to 2.1% (± 0.6%), respectively, whereas the respective values for the PC sample range from 3.2% (± 0.8%) to 6.9% (± 3.9%). As the particle diameter increases, a significant decrease in particle release is observed for the PMMA sample, whereas an increase is observed for the PC sample. Furthermore, a peak airborne release rate is observed during the first instants of PMMA exposure to thermal stress. An empirical relationship has been proposed between the duration of this peak release and the external heat flux. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Study of Enzymatic Degradation Comparison of CPP/Bionolle and CPP/PCL Blend with Modic

    International Nuclear Information System (INIS)

    Nikham; Makuuchi, K.; Yoshii, Fumeo

    2000-01-01

    Melt-blending poly propylene-co-ethylene (CPP)/poly butylene succinate (Bionolle), CPP/polyεcaprolactone (PCL) with polypropylene grafted maleic anhydride (Modic) as compatibilizer has been studied. The effect of Modic concentration on the compatibility was evaluated using the ultimate elongation at break, tensile strength and SEM micrographs. The Result show that 20 wt % and 10 % wt of Medic appears to be an optimum concentration for CPP/Bionolle and CPP/PCL blend respectively, as indicated by relatively high elongation at breaks, tensile strength and formation of co-continuous phase in the blend morphology. Enzymatic degradation of the CPP/Bionolle and CPP/PCL blend with 10 wt % of Modic was carried out using lipase AK enzyme in the phospate buffer solution pH 7.0 and incubated at the fixed temperature for 8 days. The result show that about 15 % and 86 % weight loss film of composition CPP/Bionolle>25/75 and CPP/PCL >25/75 blend respectively has been reached

  8. Doping effect on monolayer MoS2 for visible light dye degradation - A DFT study

    Science.gov (United States)

    Cheriyan, Silpa; Balamurgan, D.; Sriram, S.

    2018-04-01

    The electronic and optical properties of, Nitrogen (N), Cobalt (Co), and Co-N co-doped monolayers of MoS2 has been studied by using density functional theory (DFT) for visible light photocatalytic activity. From the calculations, it has been observed that the band gap of monolayer MoS2 has been reduced while doping. However, the band gaps of pristine and N doped MoS2 monolayers only falls in the visible region while for Co and Co-N co-doped systems, the band gap shifted to IR region. The optical calculation also confirms the results. The formation energy values of the doped system reaveal that MoS2 monolayer drops its stability while doping. To evaluate the photocatalytic response, band edge potentials of pristine and N-MoS2 are calculated, and the observed results show that compared to N-doped MoS2 monolayer, pure MoS2 is highly suitable for visible light photocatalytic dye degradation.

  9. Numerical study of the thermal degradation of isotropic and anisotropic polymeric materials

    Energy Technology Data Exchange (ETDEWEB)

    Soler, E. [Departamento de Lenguajes y Ciencias de la Computacion, ETSI Informatica, Universidad de Malaga, 29071 Malaga (Spain); Ramos, J.I. [Room I-320-D, ETS Ingenieros Industriales, Universidad de Malaga, Plaza El Ejido, s/n, 29013 Malaga (Spain)

    2005-08-01

    The thermal degradation of two-dimensional isotropic, orthotropic and anisotropic polymeric materials is studied numerically by means of a second-order accurate (in both space and time) linearly implicit finite difference formulation which results in linear algebraic equations at each time step. It is shown that, for both isotropic and orthotropic composites, the monomer mass diffusion tensor plays a role in initiating the polymerization kinetics, the formation of a polymerization kernel and the initial front propagation, whereas the later stages of the polymerization are nearly independent of the monomer mass diffusion tensor. In anisotropic polymeric composites, it has been found that the monomer mass diffusion tensor plays a paramount role in determining the initial stages of the polymerization and the subsequent propagation of the polymerization front, the direction and speed of propagation of which are found to be related to the principal directions of both the monomer mass and the heat diffusion tensors. It is also shown that the polymerization time and temperatures depend strongly on the anisotropy of the mass and heat diffusion tensors. (authors)

  10. Study of the degradation mechanisms of amines used for the capture of CO2 in industrial fumes

    International Nuclear Information System (INIS)

    Lepaumier, H.

    2008-10-01

    Global warming leads to reduce greenhouse gas emissions. Post combustion CO 2 capture with solvent is the most advanced technology to reduce CO 2 emissions in industrial fumes. A major problem associated with chemical absorption of CO 2 using the benchmark ethanolamine (MEA) is solvent degradation through irreversible side reactions with CO 2 and O 2 which leads to numerous harmful impacts to the process: corrosion, solvent loss, foaming, fouling, and viscosity increase. So, developing new amines with higher chemical stability is essential. This work is based on the chemical stability study of 17 different molecules. Their structures have been chosen in order to establish structure-property relationships: alkanolamines, known for gas treatment application (MEA, DEA, MDEA, AMP...), di-amines, and tri-amines without alcohol function. Impact of temperature, CO 2 , and O 2 on degradation has been studied. Strong experimental conditions have been used to observe significant degradation after a 15 days experiment. Separation, identification and quantification of degradation products have been performed by using different testing instructions such as gas chromatography, mass spectrometry, ionic chromatography and NMR. Different mechanisms are proposed to explain most of degradation compounds. Radical reactions (dealkylation, alkylation, ring-closure reactions and piperazinones formation) are involved under O 2 pressure whereas CO 2 induces ionic reactions (dealkylation, alkylation, addition, ring-closure reactions and oxazolidinones or imidazolidinones formation). Large discrepancies of stability are noticed among the different amines. Knowledge of degradation products and reaction mechanisms has thus permitted to establish some relationships between structure and chemical stability: for example, role of the amine function (primary, secondary, tertiary), impact of alkyl chain length between the two amino groups and steric hindrance. (author)

  11. The mechanism study of efficient degradation of hydrophobic nonylphenol in solution by a chemical-free technology of sonophotolysis

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L.J.; Chu, W., E-mail: cewchu@polyu.edu.hk; Lee, Po-Heng; Wang, Jian

    2016-05-05

    Highlights: • pH influenced NP sonophotolysis by changing its existing form and light absorption. • NO{sub 3}{sup −} accelerated NP sonophotolysis while HCO{sub 3}{sup −} showed insignificant influence. • Both ortho- and meta-hydroxy-NP species can exist together thermodynamically. • Only the ortho-4-nonyl-benzoquinone is dominant thermodynamically. • The mechanism of ortho-hydroxy-NP formation was the addition of HO· and H· - Abstract: Nonylphenol is a hydrophobic endocrine disrupting compound, which can inhibit the growth of sewage bacteria in biological processes. This study investigated the degradation of 4-n-nonylphenol (NP) in water by a chemical-free technology of sonophotolysis with emphasis on the impacts of several important parameters, including light intensity, solution pH, two commonly seen inorganic ions (i.e. NO{sub 3}{sup −} and HCO{sub 3}{sup −}), and principally on the examination of degradation mechanisms. It was found that, solution pH could significantly influence both NP degradation efficiency and the synergistic effect of sonophotolytic process, where higher synergistic effect was obtained at more acidic condition. In addition, the presence of NO{sub 3}{sup −} accelerated NP degradation by both acting as a photosensitizer and providing NO{sub 2}· radicals, while HCO{sub 3}{sup −} had little effect on NP degradation. Identification of intermediates of NP degradation indicated that NP sonophotolysis was mainly initiated by the formation of hydroxy-NP, and a new intermediate di-hydroxy-NP was identified for the first time ever in this study. Through thermodynamic analysis, results indicated that both ortho- and meta-hydroxy-NP species can coexist in the solution but the ortho-4-NBZQ (4-nonyl-benzoquinone) is dominant. In addition, the mechanism of ortho-hydroxy-NP formation was suggested by the addition of HO· and H· radicals.

  12. Study of aging and ordering processes in titanium carbide

    International Nuclear Information System (INIS)

    Arbuzov, M.P.; Khaenko, B.V.; Kachkovskaya, Eh.T.

    1977-01-01

    Aging and ordering processes in titanium carbide were investigated on monocrystals (fragments of alloys) with the aid of roentgenographic method. The sequence of phase transformations during aging was ascertained,and a monoclinic structure of the carbon atoms ordering is suggested. The microhardness of titanium carbide was studied as a function of the heat treatment of alloys and the main factors (ordering and dislocation structure) which govern the difference in the microhardness of hardened and aged (annealed) specimens were determined

  13. Rheological Study of Ageing Soft Glasses of Laponite

    Indian Academy of Sciences (India)

    Table of contents. Rheological Study of Ageing Soft Glasses of Laponite · Colloidal glasses · Laponite Na+0.7[(Si8Mg5.5Li0.3)O20(OH)4]–0.7 · Effect of salt (NaCl) · Arrested state · Relaxation dynamics · Rheology of aging system · Slide 8 · Experimental Protocol · Ageing and Creep experiments · Slide 11 · Slide 12.

  14. Retirement age and the age of onset of Alzheimer's disease: results from the ICTUS study.

    Directory of Open Access Journals (Sweden)

    Catherine Grotz

    Full Text Available To test whether deferred retirement is associated with delayed onset of Alzheimer's disease (AD, and, if so, to determine whether retirement age still predicts the age at onset of AD when two potential biases are considered.The study sample was gathered from the Impact of Cholinergic Treatment Use/Data Sharing Alzheimer cohort (ICTUS/DSA, a European study of 1,380 AD patients. Information regarding retirement age, onset of symptoms and covariates was collected at baseline whereas age at diagnosis was gathered from the patient's medical record prior to study entry. Linear mixed models, adjusted for gender, education, occupation, center, country, household income, depression and cardiovascular risk factors were conducted on 815 patients.(1 The global analyses (n = 815 revealed that later age at retirement was associated with later age at diagnosis (β = 0.31, p < 0.0001; (2 once the selection bias was considered (n = 637, results showed that this association was weaker but remained significant (β = 0.15, p = 0.004; (3 once the bias of the reverse causality (i.e., the possibility that subjects may have left the workforce due to prior cognitive impairment was considered (n = 447, the effect was no longer significant (β = 0.06, p = 0.18.The present study supports that there is an association between retirement age and age at onset of AD. However, the strength of this association appears to be overestimated due to the selection bias. Moreover, the causality issue remains unresolved. Further prospective investigations are mandatory in order to correctly address this question.

  15. Subjective age and personality development: a 10-year study.

    Science.gov (United States)

    Stephan, Yannick; Sutin, Angelina R; Terracciano, Antonio

    2015-04-01

    Personality theory and research typically focus on chronological age as a key indicator of personality development. This study examines whether the subjective experience of age is an alternative marker of the biomedical and psychosocial factors that contribute to individual differences in personality development. The present study uses data from the Midlife in the United States longitudinal survey (N = 3,617) to examine how subjective age is associated with stability and change in personality and the dynamic associations between subjective age and personality traits over a 10-year period. Regression analyses indicated that a younger subjective age at baseline was associated with increases in Openness, Conscientiousness, and Agreeableness; correlated changes were also found. The rank-order stability of Extraversion and Openness and overall profile consistency were higher among those with a younger subjective age at baseline and were also associated with the rate of subjective aging over time. The present study reveals that beyond chronological age, the age an individual feels is related to changes in characteristic ways of thinking, feeling, and behaving over time. © 2014 Wiley Periodicals, Inc.

  16. [Studies on the degradation of paracetamol in sono-electrochemical oxidation].

    Science.gov (United States)

    Dai, Qi-Zhou; Ma, Wen-Jiao; Shen, Hong; Chen, Jun; Chen, Jian-Meng

    2012-07-01

    A novel lead dioxide electrodes co-doped with rare earth and polytetrafluoroethylene (PTFE) were prepared by the electrode position method and applied as anodes in sono-electrochemical oxidation for pharmaceutical wastewater degradation. The results showed that the APAP removal and the mineralization efficiency reached an obvious increase, which meant that the catalytic efficiency showed a significant improvement in the use of rare-earth doped electrode. The effects of process factors showed that the condition of the electrode had the best degradation efficiency with doped with Ce2O3 under electrolyte concentration of 14.2 g x L(-1), 49.58 W x cm(-2), 50 Hz, pH = 3, 71.43 mA x cm(-2). The APAP of 500 mg x L(-1) removal rate reached 92.20% and its COD and TOC values declined to 79.95% and 58.04%, the current efficiency reached 45.83% after degradation process for 2.0 h. The intermediates were monitored by the methods of GC-MS, HPLC, and IC. The main intermediates of APAP were p-benzoquinone, benzoic acid, acetic acid, maleic acid, oxalic acid, formic acid etc, and the final products were carbon dioxide and water. The goal of completely degradation of pollutant was achieved and a possible degradation way was proposed.

  17. A study on radiation technological degradation of organic chloride wastewater--exemplified by TCE and PCE.

    Science.gov (United States)

    Huang, Sheng-Kai; Hsieh, Ling-Ling; Chen, Chia-Chieh; Lee, Po-Hsiu; Hsieh, Bor-Tsung

    2009-01-01

    This paper describes the potential of using gamma radiation technology to degrade trichloroethylene (TCE) and perchloroethylene (PCE) wastewater. The experimental method is divided into two parts: (1) using the gamma-ray to irradiate the TCE and PCE solution, the dose-rate is 10Gy/minute, the irradiation dosage is 0-2.5kGy and (2) self-making the UV irradiation system, the tube specification is 254nm and 6W, and turning on 8 tubes at the same time to make the irradiation. The efficiency of degradation ratio for gamma-ray is better than UV in the range of 0.1-250ppm; for example, as for the concentration of 0.1ppm, when TCE is degraded to D(90) and T(90), the gamma-ray only needed 46.7Gy and took about 4.67 minutes, but UV needed to take about 28.1 minutes. The dose-concentration equations of TCE and PCE are: TCE: y=44.58+8.832x, R(2)=0.999; and PCE: y=81.33+12.81x, R(2)=0.997. We verified that the radiation technology is able to effectively degrade the organic chlorine wastewater without yielding the secondary pollution, and the TCE and PCE that degraded by using gamma-ray will be reached US-EPA and Taiwan Effluent Standard (5ppb).

  18. A study on radiation technological degradation of organic chloride wastewater-Exemplified by TCE and PCE

    International Nuclear Information System (INIS)

    Huang, S.-K.; Hsieh, L.-L.; Chen, C.-C.; Lee, P.-H.; Hsieh, B.-T.

    2009-01-01

    This paper describes the potential of using gamma radiation technology to degrade trichloroethylene (TCE) and perchloroethylene (PCE) wastewater. The experimental method is divided into two parts: (1) using the γ-ray to irradiate the TCE and PCE solution, the dose-rate is 10 Gy/minute, the irradiation dosage is 0-2.5 kGy and (2) self-making the UV irradiation system, the tube specification is 254 nm and 6 W, and turning on 8 tubes at the same time to make the irradiation. The efficiency of degradation ratio for γ-ray is better than UV in the range of 0.1-250 ppm; for example, as for the concentration of 0.1 ppm, when TCE is degraded to D 90 and T 90 , the γ-ray only needed 46.7 Gy and took about 4.67 minutes, but UV needed to take about 28.1 minutes. The dose-concentration equations of TCE and PCE are: TCE: y=44.58+8.832x, R 2 =0.999; and PCE: y=81.33+12.81x, R 2 =0.997. We verified that the radiation technology is able to effectively degrade the organic chlorine wastewater without yielding the secondary pollution, and the TCE and PCE that degraded by using γ-ray will be reached US-EPA and Taiwan Effluent Standard (5 ppb).

  19. A study on radiation technological degradation of organic chloride wastewater-Exemplified by TCE and PCE

    Energy Technology Data Exchange (ETDEWEB)

    Huang, S.-K.; Hsieh, L.-L. [Institute of Radiological Science, Central Taiwan University of Science and Technology, No. 11, Buzih Lane, Beitun District, Taichung City 40601, Taiwan (China); Chen, C.-C. [Isotope Application Division, Institute of Nuclear Energy Research, Taiwan (China); Lee, P.-H. [Institute of Radiological Science, Central Taiwan University of Science and Technology, No. 11, Buzih Lane, Beitun District, Taichung City 40601, Taiwan (China); Hsieh, B.-T. [Institute of Radiological Science, Central Taiwan University of Science and Technology, No. 11, Buzih Lane, Beitun District, Taichung City 40601, Taiwan (China)], E-mail: bthsieh@ctust.edu.tw

    2009-07-15

    This paper describes the potential of using gamma radiation technology to degrade trichloroethylene (TCE) and perchloroethylene (PCE) wastewater. The experimental method is divided into two parts: (1) using the {gamma}-ray to irradiate the TCE and PCE solution, the dose-rate is 10 Gy/minute, the irradiation dosage is 0-2.5 kGy and (2) self-making the UV irradiation system, the tube specification is 254 nm and 6 W, and turning on 8 tubes at the same time to make the irradiation. The efficiency of degradation ratio for {gamma}-ray is better than UV in the range of 0.1-250 ppm; for example, as for the concentration of 0.1 ppm, when TCE is degraded to D{sub 90} and T{sub 90}, the {gamma}-ray only needed 46.7 Gy and took about 4.67 minutes, but UV needed to take about 28.1 minutes. The dose-concentration equations of TCE and PCE are: TCE: y=44.58+8.832x, R{sup 2}=0.999; and PCE: y=81.33+12.81x, R{sup 2}=0.997. We verified that the radiation technology is able to effectively degrade the organic chlorine wastewater without yielding the secondary pollution, and the TCE and PCE that degraded by using {gamma}-ray will be reached US-EPA and Taiwan Effluent Standard (5 ppb)

  20. MECHANISTIC STUDIES OF SURFACE CATALYZED H2O2 DECOMPOSITION AND CONTAMINANT DEGRADATION IN THE PRESENCE OF SAND. (R823402)

    Science.gov (United States)

    This study examined the mechanism and kinetics of surface catalyzed hydrogen peroxide decomposition and degradation of contaminants in the presence of sand collected from an aquifer and a riverbed. Batch experiments were conducted using variable sand concentrations (0.2 to 1.0&nb...

  1. Thermo-oxidative degradation study of melt-processed polyethylene and its blend with polyamide using time-resolved rheometry

    CSIR Research Space (South Africa)

    Salehiyan, Reza

    2017-05-01

    Full Text Available Time-resolved mechanical spectroscopy (TRMS) was conducted to study the thermo-oxidative degradation of linear low density polyethylene (LLDPE) samples with different thermal histories and their blends with a polyamide (PA6) in the melt state. Neat...

  2. Study of kinetics of 2,3-diphosphoglycerate degradation by 31P-NMR technique in depleted human erythrocytes

    International Nuclear Information System (INIS)

    Ataullakhanov, F.I.; Vitvitskii, V.M.; Dubinskaya, E.I.; Dubinskii, V.Z.

    1986-01-01

    The kinetics of 2,3-diphosphoglycerate degradation in depleted human erythrocytes was studied by the high-resolution 31 P-NMR technique. A plateau was found on the kinetic curve in the first 1.5-2 h after the beginning of depletion. The mechanisms that may be responsible for the existence of such a plateau are discussed

  3. Silicon-depth profiling with Rutherford backscattering in photoresist layers; a study on the effects of degradation

    NARCIS (Netherlands)

    IJzendoorn, van L.J.; Schellekens, J.P.W.

    1989-01-01

    The reaction of a silicon-containing vapor with a photoresist layer, as used in some dry developable lithographic processes, was studied with Rutherford backscattering spectrometry. Degradation of the polymer layer under ion beam irradiation was observed, but it was found that this had no influence

  4. Pilot study protocol to inform a future longitudinal study of ageing using linked administrative data: Healthy AGeing in Scotland (HAGIS).

    Science.gov (United States)

    Douglas, Elaine; Rutherford, Alasdair; Bell, David

    2018-01-10

    Population ageing is a welcome testament to improvements in the social, economic and health circumstances over the life course. However, these successes necessitate that we understand more about the pathways of ageing to plan and cost our health and social care services, to support our ageing population to live healthier for longer and to make adequate provisions for retirement. Longitudinal studies of ageing facilitate such understanding in many countries around the world. Scotland presently does not have a longitudinal study of ageing, despite dramatic increases to its ageing population and its poor health record. Healthy AGeing in Scotland (HAGIS) constitutes the launch of Scotland's first comprehensive longitudinal study of ageing. A sample of 1000 people aged 50+ years will be invited to take part in a household social survey. The innovative sampling procedure used administrative data to identify eligible households. Anonymised survey responses will be linked to administrative data. Ethics approval was obtained from the host institution for the study design and from the Public Benefits and Privacy Panel for administrative data linkage. Anonymised survey data will be deposited with the UK Data Service. A subset of survey data, harmonised with other global ageing studies, will be available via the Gateway to Global Aging platform. These data will enable powerful cross-country comparisons across the social, economic and health domains that will be relevant for national and international research.Research publications from the HAGIS team will be disseminated through journal articles and national and international conferences. The findings will support current and future research and policy debate on ageing populations. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  5. Aging and Alzheimer's Disease: Lessons from the Nun Study.

    Science.gov (United States)

    Snowdon, David A.

    1997-01-01

    Describes a woman who maintained high cognitive test scores until her death at 101 years of age despite anatomical evidence of Alzheimer's disease. The woman was part of a larger "Nun Study" in which 678 sisters donated their brains to teach others about the etiology of aging and Alzheimer's disease. Findings are discussed. (RJM)

  6. Study on kinetic of strain-aging in zircaloy-4

    International Nuclear Information System (INIS)

    Gomes, P.A.

    1977-01-01

    The strain-aging in zircaloy-4 has been investigated in this work and a study of the general problems involving this phenomenon has been realized in Zirconium and its alloys. It has been verified that a yield point appears in the Zircaloy-4, when it is submitted to strain-aging treatment between the temperatures 200 0 C and 400 0 C. (author)

  7. Prolonged aerobic degradation of shredded and pre-composted municipal solid waste: report from a 21-year study of leachate quality characteristics.

    Science.gov (United States)

    Grisey, Elise; Aleya, Lotfi

    2016-01-01

    The objective of this study was to assess the degree of long-term waste maturation at a closed landfill (Etueffont, France) over a period of 21 years (1989-2010) through analysis of the physicochemical characteristics of leachates as well as biochemical oxygen demand (BOD), chemical oxygen demand (COD), and metal content in waste. The results show that the leachates, generated in two different sections (older and newer) of the landfill, have low organic, mineral, and metallic loads, as the wastes were mainly of household origin from a rural area where sorting and composting were required. Based on pH and BOD/COD assessments, leachate monitoring in the landfill's newer section showed a rapid decrease in the pollution load over time and an early onset of methanogenic conditions. The closing of the older of the two sections contributed to a significant decline for the majority of parameters, attributable to degradation and leaching. A gradual decreasing trend was observed after waste placement had ceased in the older section, indicating that degradation continued and the waste mass had not yet fully stabilized. At the end of monitoring, leachates from the two landfill linings contained typical old leachates in the maturation period, with a pH ≥ 7 and a low BOD/COD ratio indicating a low level of waste biodegradability. Age actually contributes to a gradual removal of organic, inorganic, and metallic wastes, but it is not the only driving factor behind advanced degradation. The lack of compaction and cover immediately after deposit extended the aerobic degradation phase, significantly reducing the amount of organic matter. In addition, waste shredding improved water infiltration into the waste mass, hastening removal of polluting components through percolation.

  8. SEM-EDX Study of the Degradation Process of Two Xenograft Materials Used in Sinus Lift Procedures

    Directory of Open Access Journals (Sweden)

    María Piedad Ramírez Fernández

    2017-05-01

    Full Text Available Some studies have demonstrated that in vivo degradation processes are influenced by the material’s physico-chemical properties. The present study compares two hydroxyapatites manufactured on an industrial scale, deproteinized at low and high temperatures, and how physico-chemical properties can influence the mineral degradation process of material performance in bone biopsies retrieved six months after maxillary sinus augmentation. Residual biomaterial particles were examined by field scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDX to determine the composition and degree of degradation of the bone graft substitute material. According to the EDX analysis, the Ca/P ratio significantly lowered in the residual biomaterial (1.08 ± 0.32 compared to the initial composition (2.22 ± 0.08 for the low-temperature sintered group, which also presented high porosity, low crystallinity, low density, a large surface area, poor stability, and a high resorption rate compared to the high-temperature sintered material. This demonstrates that variations in the physico-chemical properties of bone substitute material clearly influence the degradation process. Further studies are needed to determine whether the resorption of deproteinized bone particles proceeds slowly enough to allow sufficient time for bone maturation to occur.

  9. GRIZZLY Model of Multi-Reactive Species Diffusion, Moisture/Heat Transfer and Alkali-Silica Reaction for Simulating Concrete Aging and Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Spencer, Benjamin W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Vanderbilt Univ., Nashville, TN (United States)

    2015-09-01

    Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear power plants for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have accurate and reliable predictive tools to address concerns related to various aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to document the progress of the development and implementation of a fully coupled thermo-hydro-mechanical-chemical model in GRIZZLY code with the ultimate goal to reliably simulate and predict long-term performance and response of aged NPP concrete structures subjected to a number of aging mechanisms including external chemical attacks and volume-changing chemical reactions within concrete structures induced by alkali-silica reactions and long-term exposure to irradiation. Based on a number of survey reports of concrete aging mechanisms relevant to nuclear power plants and recommendations from researchers in concrete community, we’ve implemented three modules during FY15 in GRIZZLY code, (1) multi-species reactive diffusion model within cement materials; (2) coupled moisture and heat transfer model in concrete; and (3) anisotropic, stress-dependent, alkali-silica reaction induced swelling model. The multi-species reactive diffusion model was implemented with the objective to model aging of concrete structures subjected to aggressive external chemical attacks (e.g., chloride attack, sulfate attack, etc.). It considers multiple processes relevant to external chemical attacks such as diffusion of ions in aqueous phase within pore spaces, equilibrium chemical speciation reactions and kinetic mineral dissolution/precipitation. The moisture

  10. Matlab fractal techniques used to study the structural degradation caused by alpha radiation to laser mirrors

    Science.gov (United States)

    Ioan, M.-R.

    2018-01-01

    Almost all optical diagnostic systems associated with classical particle accelerators or with new state-of-the-art particle accelerators, such as those developed within the European Collaboration ELI-NP (Extreme Light Infrastructure-Nuclear Physics) (involving extreme power laser beams), contain in their infrastructure high quality laser mirrors, used for their reflectivity and/or their partial transmittance. These high quality mirrors facilitate the extraction and handling of optical signals. When optical mirrors are exposed to high energy ionizing radiation fields, their optical and structural properties will change over time and their functionality will be affected, meaning that they will provide imprecise information. In some experiments, being exposed to mixed laser and accelerated particle beams, the deterioration of laser mirrors is even more acute, since the destruction mechanisms of both types of beams are cumulated. The main task of the work described in this paper was to find a novel specific method to analyse and highlight such degradation processes. By using complex fractal techniques integrated in a MATLAB code, the effects induced by alpha radiation to laser mirrors were studied. The fractal analysis technique represents an alternative approach to the classical Euclidean one. It can be applied for the characterization of the defects occurred in mirrors structure due to their exposure to high energy alpha particle beams. The proposed method may be further integrated into mirrors manufacturing process, as a testing instrument, to obtain better quality mirrors (enhanced resistance to high energy ionizing beams) by using different types of reflective coating materials and different deposition techniques. Moreover, the effect of high energy alpha ionizing particles on the optical properties of the exposed laser mirrors was studied by using spectrophotometric techniques.

  11. Kinetic study of the degradation of the insecticide pymetrozine in a vegetable-field ecosystem

    International Nuclear Information System (INIS)

    Shen Guoqing; Hu Xuan; Hu Yinan

    2009-01-01

    The disappearance kinetics of pymetrozine was studied in a broccoli-field ecosystem, and an efficient method for the determination of pymetrozine in broccoli and soil was also developed. Pymetrozine residues were extracted from samples using acetonitrile. The extracts were cleaned up by liquid-liquid partitioning with dichloromethane, followed by purification with ethyl acetate, and were then determined by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detector. The average recovery was 87-93% from broccoli, and 84-90% from soil. The relative standard deviation (R.S.D.) was less than 4% in broccoli, and in soil less than 11%. These results are all within the accepted range for residue determination. The limit of detection (LOD) of pymetrozine calculated as a sample concentration (S/N ratio of 3) was 0.005 mg kg -1 . The minimum detectable quantity (MDQ) was 1 x 10 -10 g. The results of the kinetics study of pymetrozine residue showed that pymetrozine degradation in broccoli and soil coincided, with C = 1.9826 e -0.1965t and C = 15.352 e -0.4992t , respectively; the half-lives were 3.5 and 1.4 days, respectively. The final residue level was lower than the new maximum residue limit (MRL) for pymetrozine on vegetables with a harvest interval of 23 days. A dosage of 300 g a.i. hm -2 was suggested, which is considered to be safe for human beings. These results contribute to establishing the scientific basis of the dosage of pymetrozine for use in vegetable-field ecosystems.

  12. Applicability of X-ray reflectometry to studies of polymer solar cell degradation

    DEFF Research Database (Denmark)

    Andreasen, Jens Wenzel; Gevorgyan, Suren; Schleputz, C.M.

    2008-01-01

    Although degradation of polymer solar cells is widely acknowledged, the cause, physical or chemical, has not been identified. The purpose of this work is to determine the applicability of X-ray reflectometry for in situ observation of physical degradation mechanisms. We find that the rough...... interfaces of the polymer solar cell constituent layers seriously obstruct the sensitivity of the technique, rendering it impossible to elucidate changes in the layer/interface structure at the sub-nanometer level. (c) 2008 Elsevier B.V. All rights reserved....

  13. Effects of fungal degradation on the CuO oxidation products of lignin: A controlled laboratory study

    Science.gov (United States)

    Hedges, John I.; Blanchette, Robert A.; Weliky, Karen; Devol, Allan H.

    1988-11-01

    Duplicate samples of birch wood were degraded for 0, 4, 8 and 12 weeks by the white-rot fungus, Phlebia tremellosus, and for 12 weeks by 6 other white-rot and brown-rot fungi. P. tremellosus caused progressive weight losses and increased the H/C and O/C of the remnant wood by preferentially degrading the lignin component of the middle lamellae. This fungus increased the absolute (weight loss-corrected) yield of the vanillic acid CuO reaction product above its initial level and exponentially decreased the absolute yields of all other lignin-derived phenols. Total yields of syringyl phenols were decreased 1.5 times as fast as total vanillyl phenol yields. Within both phenol families, aldehyde precursors were degraded faster than precursors of the corresponding ketones, which were obtained in constant proportion to the total phenol yield. Although two other white-rot fungi caused similar lignin compositional trends, a fourth white-rot species, Coriolus versicolor, simultaneously eroded all cell wall components and did not concentrate polysaccharides in the remnant wood. Wood degraded by the three brown-rot fungi exhibited porous cell walls with greatly reduced integrity. The brown-rot fungi also preferentially attacked syringyl structural units, but degraded all phenol precursors at a much slower rate than the white-rotters and did not produce excess vanillic acid. Degradation by P. tremellosus linearly increased the vanillic acid/vanillin ratio, (Ad/Al)v, of the remnant birch wood throughout the 12 week degradation study and exponentially decreased the absolute yields of total vanillyl phenols, total syringyl phenols and the syringyl/vanillyl phenol ratio, S/V. At the highest (Ad/Al)v of 0.50 (12 week samples), total yields of syringyl and vanillyl phenols were decreased by 65% and 80%, respectively, with a resulting reduction of 40% in the original S/V. Many of the diagenetically related compositional trends that have been previously reported for lignins in natural

  14. Paracetamol - toxicity and microbial utilization. Pseudomonas moorei KB4 as a case study for exploring degradation pathway.

    Science.gov (United States)

    Żur, Joanna; Wojcieszyńska, Danuta; Hupert-Kocurek, Katarzyna; Marchlewicz, Ariel; Guzik, Urszula

    2018-09-01

    Paracetamol, a widely used analgesic and antipyretic drug, is currently one of the most emerging pollutants worldwide. Besides its wide prevalence in the literature only several bacterial strains able to degrade this compound have been described. In this study, we isolated six new bacterial strains able to remove paracetamol. The isolated strains were identified as the members of Pseudomonas, Bacillus, Acinetobacter and Sphingomonas genera and characterized phenotypically and biochemically using standard methods. From the isolated strains, Pseudomonas moorei KB4 was able to utilize 50 mg L -1 of paracetamol. As the main degradation products, p-aminophenol and hydroquinone were identified. Based on the measurements of specific activity of acyl amidohydrolase, deaminase and hydroquinone 1,2-dioxygenase and the results of liquid chromatography analyses, we proposed a mechanism of paracetamol degradation by KB4 strain under co-metabolic conditions with glucose. Additionally, toxicity bioassays and the influence of various environmental factors, including pH, temperature, heavy metals at no-observed-effective-concentrations, and the presence of aromatic compounds on the efficiency and mechanism of paracetamol degradation by KB4 strain were determined. This comprehensive study about paracetamol biodegradation will be helpful in designing a treatment systems of wastewaters contaminated with paracetamol. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Screening of SDS-degrading bacteria from car wash wastewater and study of the alkylsulfatase enzyme activity.

    Science.gov (United States)

    Shahbazi, Razieh; Kasra-Kermanshahi, Roha; Gharavi, Sara; Moosavi-Nejad, Zahra; Borzooee, Faezeh

    2013-06-01

    Sodium dodecyl sulfate (SDS) is one of the main surfactant components in detergents and cosmetics, used in high amounts as a detergent in products such as shampoos, car wash soap and toothpaste. Therefore, its bioremediation by suitable microorganisms is important. Alkylsulfatase is an enzyme that hydrolyses sulfate -ester bonds to give inorganic sulfate and alcohol. The purpose of this study was to isolate SDS-degrading bacteria from Tehran city car wash wastewater, study bacterial alkylsulfatase enzyme activity and identify the alkylsulfatase enzyme coding gene. Screening of SDS-degrading bacteria was carried out on basal salt medium containing SDS as the sole source of carbon. Amount of SDS degraded was assayed by methylene blue active substance (MBAS). Identification of the sdsA gene was carried by PCR and subsequent sequencing of the 16S rDNA gene and biochemical tests identified Pseudomonas aeruginosa. This bacterium is able to degrade 84% of SDS after four days incubation. Bacteria isolated from car wash wastewater were shown to carry the sdsA gene (670bp) and the alkylsulfatase enzyme specific activity expressed from this gene was determined to be 24.3 unit/mg. The results presented in this research indicate that Pseudomonas aeruginosa is a suitable candidate for SDS biodegradation.

  16. Age

    Science.gov (United States)

    ... adults? How can you reduce anesthesia risks in older patients? Age Age may bring wisdom but it also brings ... Ask your physician to conduct a pre-surgery cognitive test — an assessment of your mental function. The physician can use the results as a ...

  17. Kinetic study of photocatalytic degradation of carbamazepine, clofibric acid, iomeprol and iopromide assisted by different TiO2 materials--determination of intermediates and reaction pathways.

    Science.gov (United States)

    Doll, Tusnelda E; Frimmel, Fritz H

    2004-02-01

    The light-induced degradation of clofibric acid, carbamazepine, iomeprol and iopromide under simulated solar irradiation has been investigated in aqueous solutions suspended with different TiO2 materials (P25 and Hombikat UV100). Kinetic studies showed that P25 had a better photocatalytic activity for clofibric acid and carbamazepine than Hombikat UV100. For photocatalytic