Science.gov

Sample records for aging durability procedures

  1. 40 CFR Appendix Ix to Part 86 - Experimentally Determining the R-Factor for Bench Aging Durability Procedures

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-Factor for Bench Aging Durability Procedures IX Appendix IX to Part 86 Protection of Environment... the R-Factor for Bench Aging Durability Procedures The R-Factor is the catalyst thermal reactivity coefficient used in the bench aging time (BAT) equation . Manufacturers may determine the value of...

  2. 40 CFR Appendix Ix to Part 86 - Experimentally Determining the R-Factor for Bench Aging Durability Procedures

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-Factor for Bench Aging Durability Procedures IX Appendix IX to Part 86 Protection of Environment...-Factor for Bench Aging Durability Procedures The R-Factor is the catalyst thermal reactivity coefficient used in the bench aging time (BAT) equation . Manufacturers may determine the value of R...

  3. 40 CFR Appendix Ix to Part 86 - Experimentally Determining the R-Factor for Bench Aging Durability Procedures

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... in § 86.1826-08(d)(4). 3. Plot emissions (or catalyst inefficiency) versus aging time for each.... Plot the natural log (ln) of the slope of each best-fit line (determined in step 4) along the...

  4. 40 CFR Appendix Ix to Part 86 - Experimentally Determining the R-Factor for Bench Aging Durability Procedures

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... in § 86.1826-08(d)(4). 3. Plot emissions (or catalyst inefficiency) versus aging time for each.... Plot the natural log (ln) of the slope of each best-fit line (determined in step 4) along the...

  5. 40 CFR Appendix Ix to Part 86 - Experimentally Determining the R-Factor for Bench Aging Durability Procedures

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in § 86.1826-08(d)(4). 3. Plot emissions (or catalyst inefficiency) versus aging time for each.... Plot the natural log (ln) of the slope of each best-fit line (determined in step 4) along the...

  6. 40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... paragraph. (h) Emission component durability. . For guidance see 40 CFR 86.1845-01 (e). (i) If EPA... conducted by the manufacturer using good engineering judgement. (d) Bench aging refueling durability...) Combined whole-vehicle and bench-aging programs. Manufacturers may combine the results of whole...

  7. 40 CFR 86.1823-08 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... guidelines of the high mileage IUVP program (ref: 40 CFR 86.1845-04). (3) Manufacturers may use previously...) Emission component durability. . For guidance see 40 CFR 86.1823-01(e). (h) Application of the durability... control system may be aged on an engine dynamometer using methods that will replicate the aging...

  8. Durability of a novel durable bait for control of subterranean termites (Isoptera: Rhinotermitidae): results of five-year field aging studies.

    PubMed

    Eger, J E; Hamm, R L; Demark, J J; Chin-Heady, E; Tolley, M P; Benson, E P; Zungoli, P A; Smith, M S; Spomer, N A

    2014-06-01

    A durable termite bait containing 0.5% noviflumuron was evaluated for physical durability, retention of active ingredient, consumption by termites, and toxicity to termites over 5 yr in field studies at locations in Indiana, Mississippi, and South Carolina. Plots in Indiana and Mississippi included both natural rainfall and irrigated plots, while plots in South Carolina received only natural rainfall. Samples collected every 3 mo for the first 4 yr were evaluated for consumption with a 7 d no-choice bioassay using Reticulitermes flavipes (Kollar). Consumption and toxicity of 5 yr samples were evaluated in similar bioassays conducted for 42 d. Durable baits received from field sites had some cracking, and a small amount of external flaking, but no major deterioration based on visual observation. There were no significant differences in noviflumuron concentration over the 5-yr period and no trend toward reduced concentrations of noviflumuron over time. Consumption of aged durable baits over 4 yr was variable, but termites usually consumed more aged durable bait than fresh durable bait and the differences were frequently significant. There were some exceptions, but termites consumed significantly more fresh durable bait than aged durable bait in only 4% of observations. When 5 yr samples were evaluated, consumption was lowest for fresh durable bait and termites consumed significantly more aged durable bait from irrigated plots in Indiana and from both natural and irrigated plots in Mississippi than fresh durable bait. Survival of termites fed blank durable bait was significantly higher than that for termites fed any of the baits containing noviflumuron and there were no significant differences in survival among the noviflumuron durable baits. Our results suggest that the bait would be durable for at least 5 yr and possibly longer under most environmental conditions. PMID:25026683

  9. Durability of a novel durable bait for control of subterranean termites (Isoptera: Rhinotermitidae): results of five-year field aging studies.

    PubMed

    Eger, J E; Hamm, R L; Demark, J J; Chin-Heady, E; Tolley, M P; Benson, E P; Zungoli, P A; Smith, M S; Spomer, N A

    2014-06-01

    A durable termite bait containing 0.5% noviflumuron was evaluated for physical durability, retention of active ingredient, consumption by termites, and toxicity to termites over 5 yr in field studies at locations in Indiana, Mississippi, and South Carolina. Plots in Indiana and Mississippi included both natural rainfall and irrigated plots, while plots in South Carolina received only natural rainfall. Samples collected every 3 mo for the first 4 yr were evaluated for consumption with a 7 d no-choice bioassay using Reticulitermes flavipes (Kollar). Consumption and toxicity of 5 yr samples were evaluated in similar bioassays conducted for 42 d. Durable baits received from field sites had some cracking, and a small amount of external flaking, but no major deterioration based on visual observation. There were no significant differences in noviflumuron concentration over the 5-yr period and no trend toward reduced concentrations of noviflumuron over time. Consumption of aged durable baits over 4 yr was variable, but termites usually consumed more aged durable bait than fresh durable bait and the differences were frequently significant. There were some exceptions, but termites consumed significantly more fresh durable bait than aged durable bait in only 4% of observations. When 5 yr samples were evaluated, consumption was lowest for fresh durable bait and termites consumed significantly more aged durable bait from irrigated plots in Indiana and from both natural and irrigated plots in Mississippi than fresh durable bait. Survival of termites fed blank durable bait was significantly higher than that for termites fed any of the baits containing noviflumuron and there were no significant differences in survival among the noviflumuron durable baits. Our results suggest that the bait would be durable for at least 5 yr and possibly longer under most environmental conditions.

  10. 40 CFR 86.1823-01 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... Either a deterioration factor (DF) is calculated and applied to the emission data vehicle (EDV) emission... be included in the calculations. (5) A procedure may be employed to identify and remove from the DF... life periods as applicable. Separate DF's are calculated for each durability group except as...

  11. 40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1825-08 Durability demonstration procedures for refueling emissions. This section applies to 2008 and later model year...

  12. 40 CFR 86.1823-08 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-specific FTP and HFET deterioration factors for CH3OH (methanol), HCHO (formaldehyde), C2H5OH (ethanol... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Durability demonstration procedures for exhaust emissions. 86.1823-08 Section 86.1823-08 Protection of Environment...

  13. 40 CFR 86.1825-01 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1825-01 Durability demonstration procedures for refueling emissions. This section applies to light-duty vehicles, light-duty...

  14. 40 CFR 86.1823-01 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1823-01 Durability demonstration procedures for exhaust emissions. This section applies to light-duty vehicles, light-duty...

  15. Durability of polymeric composites after elevated temperature aging

    NASA Astrophysics Data System (ADS)

    Poole, Eric Luther

    The Compression After Impact (CAI) strength of polymeric composites after long term elevated temperature aging is studied. Aging temperatures range from 149sp°C to 204sp°C (300sp°F to 400sp°F). Two types of matrix material are studied, a thermoset bismaleimide (5260) and a thermoplastic polyimide (K3B). Glass transition temperature (Tsb{g}) and fracture toughness are measured after aging. Microscopy and Secondary Ion Mass Spectroscopy (SIMS) are used to evaluate the aged composites. Out-of-plane bending of the CAI specimens during compression is measured by shadow moire. Moire interferometry is used to determine in-plane displacement and strain fields around the impact damage. Results show that the CAI strength degrades with aging for both K3B and 5260. The 5260 matrix suffers from thermo-oxidative degradation at higher temperatures. Surface decomposition causes weight loss and reduces mechanical properties. The CAI strength of the K3B matrix composite also decreases after aging. Evidence of an oxidation reaction is found in the K3B polymer by SIMS, but no weight loss is associated with this chemical reaction. Measured changes in fracture toughness and Tsb{g} do not correlate with CAI strength degradation. Stiffness changes due to aging are insignificant in this study. The degradation region is measured by microscopy near the surface of composites after long aging times. The depth of the degradation zone is dependent on aging time. Degradation growth is modeled with finite elements using diffusion/reaction governing equations. Finite element results agree well with the experimental data.

  16. 40 CFR Appendix Xv to Part 86 - Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for Diesel Cycle Vehicles Equipped With Periodically Regenerating Trap Oxidizer Systems Certifying to the Provisions of Part 86, Subpart R XV Appendix XV to Part 86 Protection of...

  17. 40 CFR Appendix Xv to Part 86 - Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for Diesel Cycle Vehicles Equipped With Periodically Regenerating Trap Oxidizer Systems Certifying to the Provisions of Part 86, Subpart R XV Appendix XV to Part 86 Protection of...

  18. 40 CFR Appendix Xv to Part 86 - Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for Diesel Cycle Vehicles Equipped With Periodically Regenerating Trap Oxidizer Systems Certifying to the Provisions of Part 86, Subpart R XV Appendix XV to Part 86 Protection of...

  19. Evaluation of stone durability using a combination of ultrasound, mechanical and accelerated aging tests

    NASA Astrophysics Data System (ADS)

    Molina, E.; Cultrone, G.; Sebastián, E.; Alonso, F. J.

    2013-06-01

    The durability of a rock when exposed to decay agents is an important criterion when assessing its quality as a building material. Our study focuses on six varieties of natural stone (two limestones, one dolostone, one travertine and two sandstones) that are widely used in both new and historical buildings. In order to assess their quality, we measured and characterized their dynamic elastic properties using ultrasounds, we measured their compressive strength using the uniaxial compression test and we evaluated their durability by means of accelerated aging tests (freeze-thaw and salt crystallization). In order to get a full picture of the decay suffered by the different stones, we determined the composition and amount of the clay fraction of the six stones. We also observed small fragments subjected to the salt crystallization test under an environmental scanning electron microscope to study any textural change and measured the changes of colour on the surface with a spectrophotometer. Finally, we analysed the pore system of the stones before and after their deterioration using mercury injection porosimetry. We then compared the results for the different stones and found that dolostone obtained the best results, while the two limestones proved to be the least durable and had the lowest compressive strength.

  20. 40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... paragraph. (h) Emission component durability. . For guidance see 40 CFR 86.1845-01 (e). (i) If EPA.... Refer to the provisions of §§ 86.1811, 86.1812, 86.1813, 86.1814, and 86.1815 to determine...

  1. 40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... paragraph. (h) Emission component durability. . For guidance see 40 CFR 86.1845-01 (e). (i) If EPA.... Refer to the provisions of §§ 86.1811, 86.1812, 86.1813, 86.1814, and 86.1815 to determine...

  2. 40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... paragraph. (h) Emission component durability. . For guidance see 40 CFR 86.1845-01 (e). (i) If EPA.... Refer to the provisions of §§ 86.1811, 86.1812, 86.1813, 86.1814, and 86.1815 to determine...

  3. 40 CFR 86.1824-01 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1824-01 Durability... available in any state in the United States. Unless otherwise approved by the Administrator,...

  4. 40 CFR 86.1824-08 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1824-08 Durability... commercially available in any state in the United States. Unless otherwise approved by the Administrator,...

  5. 40 CFR 86.1823-08 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... unrepresentative data from the data set using good engineering judgement. The manufacturer must provide EPA with... emissions deterioration impact of the design differences between the vehicles included in the data set... consists of conducting mileage accumulation and periodic testing on the durability data vehicle,...

  6. Loop electrosurgical excision procedure: an effective, inexpensive, and durable teaching model.

    PubMed

    Connor, R Shae; Dizon, A Mitch; Kimball, Kristopher J

    2014-12-01

    The effectiveness of simulation training for enhancing operative skills is well established. Here we describe the construction of a simple, low-cost model for teaching the loop electrosurgical excision procedure. Composed of common materials such as polyvinyl chloride pipe and sausages, the simulation model, shown in the accompanying figure, can be easily reproduced by other training programs. In addition, we also present an instructional video that utilizes this model to review loop electrosurgical excision procedure techniques, highlighting important steps in the procedure and briefly addressing challenging situations and common mistakes as well as strategies to prevent them. The video and model can be used in conjunction with a simulation skills laboratory to teach the procedure to students, residents, and new practitioners. PMID:24887318

  7. 40 CFR Appendix I to Subpart V of... - Recommended Test Procedures and Test Criteria and Recommended Durability Procedures To...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (−20 °F) for 70 hours and at 70 °C (158 °F) for 24 hours, with a commercial grade fuel or equivalent. b... the low limit as established in 1.b. D. Positive Crankcase Ventilation (PCV) Valve 1. Test Procedure and Criteria a. Measure the flow of the PCV valve in standard cubic feet per minute (SCFM)...

  8. 40 CFR Appendix I to Subpart V of... - Recommended Test Procedures and Test Criteria and Recommended Durability Procedures To...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (−20 °F) for 70 hours and at 70 °C (158 °F) for 24 hours, with a commercial grade fuel or equivalent. b... the low limit as established in 1.b. D. Positive Crankcase Ventilation (PCV) Valve 1. Test Procedure and Criteria a. Measure the flow of the PCV valve in standard cubic feet per minute (SCFM)...

  9. Rapid evaluation of the durability of cortical neural implants using accelerated aging with reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Takmakov, Pavel; Ruda, Kiersten; Phillips, K. Scott; Isayeva, Irada S.; Krauthamer, Victor; Welle, Cristin G.

    2015-04-01

    Objective. A challenge for implementing high bandwidth cortical brain-machine interface devices in patients is the limited functional lifespan of implanted recording electrodes. Development of implant technology currently requires extensive non-clinical testing to demonstrate device performance. However, testing the durability of the implants in vivo is time-consuming and expensive. Validated in vitro methodologies may reduce the need for extensive testing in animal models. Approach. Here we describe an in vitro platform for rapid evaluation of implant stability. We designed a reactive accelerated aging (RAA) protocol that employs elevated temperature and reactive oxygen species (ROS) to create a harsh aging environment. Commercially available microelectrode arrays (MEAs) were placed in a solution of hydrogen peroxide at 87 °C for a period of 7 days. We monitored changes to the implants with scanning electron microscopy and broad spectrum electrochemical impedance spectroscopy (1 Hz-1 MHz) and correlated the physical changes with impedance data to identify markers associated with implant failure. Main results. RAA produced a diverse range of effects on the structural integrity and electrochemical properties of electrodes. Temperature and ROS appeared to have different effects on structural elements, with increased temperature causing insulation loss from the electrode microwires, and ROS concentration correlating with tungsten metal dissolution. All array types experienced impedance declines, consistent with published literature showing chronic (>30 days) declines in array impedance in vivo. Impedance change was greatest at frequencies <10 Hz, and smallest at frequencies 1 kHz and above. Though electrode performance is traditionally characterized by impedance at 1 kHz, our results indicate that an impedance change at 1 kHz is not a reliable predictive marker of implant degradation or failure. Significance. ROS, which are known to be present in vivo, can create

  10. Thermoclastic and cryoclastic action on calcareous building stone: durability to artificial ageing

    NASA Astrophysics Data System (ADS)

    Germinario, Luigi; Andriani, Gioacchino Francesco; Laviano, Rocco

    2014-05-01

    were petrographically characterized through optical microscopy on thin section, followed by a geotechnical parameterization with petrophysical measurements (dry density, total porosity, MIP porosity) and indirect ultrasonic and sclerometric tests. Then, after every 20 ageing cycles, the same tests stated above were carried out; in addition, the measurement of residual strains and SEM observations were performed. With this methodology, the gradual modifications in fabric, petrophysical and mechanical properties of the tested stone were analyzed. The results revealed a high durability of the material to the conditions of ageing experimented. The main modifications of the samples concerned fabric, i.e. microcracking due to thermoclastic and cryoclastic action, which occurred only in limited areas for an uneven distribution of internal stresses. For this reason, no evident effects on the macroscopic integrity and physico-mechanical performance were noted, whereas the stone almost preserved the original strength and elasticity. Finally, the data gathered were used to suggest a method for the evaluation of the vulnerability of "pietra gentile" to freeze-thaw microcracking, based on the peculiar porosimetric distribution and the environmental conditions of weathering. New information are globally provided about a stone material that has been largely used in the Apulian monumental heritage, but has received scarce attention from the archaeometric research so far.

  11. 40 CFR Appendix I to Subpart V of... - Recommended Test Procedures and Test Criteria and Recommended Durability Procedures To...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... fluid (Stoddard solvent or equivalent) from a 10 stroke cycle,* within ±30% of the volume from a 10 stroke cycle of an original equipment plunger or diaphragm assembly. *10 stroke cycle: 10 strokes from... intended to cover multiple vehicle or engine configurations, converter aging may be obtained per...

  12. School age test or procedure preparation

    MedlinePlus

    ... appropriate. Older school-age children might view this approach as childish. Consider your child's intellectual needs before using this type of communication. Older children may benefit from films that show ...

  13. Proton exchange membrane fuel cell model for aging predictions: Simulated equivalent active surface area loss and comparisons with durability tests

    NASA Astrophysics Data System (ADS)

    Robin, C.; Gérard, M.; Quinaud, M.; d'Arbigny, J.; Bultel, Y.

    2016-09-01

    The prediction of Proton Exchange Membrane Fuel Cell (PEMFC) lifetime is one of the major challenges to optimize both material properties and dynamic control of the fuel cell system. In this study, by a multiscale modeling approach, a mechanistic catalyst dissolution model is coupled to a dynamic PEMFC cell model to predict the performance loss of the PEMFC. Results are compared to two 2000-h experimental aging tests. More precisely, an original approach is introduced to estimate the loss of an equivalent active surface area during an aging test. Indeed, when the computed Electrochemical Catalyst Surface Area profile is fitted on the experimental measures from Cyclic Voltammetry, the computed performance loss of the PEMFC is underestimated. To be able to predict the performance loss measured by polarization curves during the aging test, an equivalent active surface area is obtained by a model inversion. This methodology enables to successfully find back the experimental cell voltage decay during time. The model parameters are fitted from the polarization curves so that they include the global degradation. Moreover, the model captures the aging heterogeneities along the surface of the cell observed experimentally. Finally, a second 2000-h durability test in dynamic operating conditions validates the approach.

  14. Durability of induced heat tolerance by short-term heat challenge at broilers marketing age.

    PubMed

    Soleimani, A F; Kasim, A; Alimon, A R; Zulkifli, I

    2008-09-01

    A trial was conducted to determine the influence of short-term exposure to high ambient temperature at 28 and 35 days of age on deep body temperatures (Tb) and subsequent growth of birds until 42 days of age. A total of 90 day old chicks were reared in stainless steel battery cages and were assigned at random into 18 pens of 5 birds each, with 9 pens containing males and another 9 pens containing females. Three treatment groups, each represented by 3 male and 3 female pens, were represented by T1 without any heat exposure, T2 with heat exposure starting at day 28 and T3 with heat exposure starting at day 35. Heat stress was defined as 180 min exposure to 35 +/- 1 degrees C. Tb and body weights were measured at 35, 37 and 39 days of age immediately following heat exposure. Heat stress resulted in higher Tb and Onset of heat stress at 28 days resulted in significantly lower Tb than onset of heat stress at 35 days. Lower Tb in T2 than T3 permitted recovery in body weight at 42 days. Sexes responded similarly to heat stress. PMID:19266934

  15. The effects of environmental aging on the durability of glass/epoxy composites

    NASA Astrophysics Data System (ADS)

    Kajorncheappunngam, Somjai

    1999-11-01

    Glass fiber reinforced plastics (GFRPs) are beginning to be used as structural materials in construction. However, their mechanical properties can degrade after prolonged exposure to the environment. Understanding this degradation was the focus of this research. Epoxy neat resin and glass/epoxy composite samples were soaked in four different solutions (distilled water, saturated salt solution, 5 M NaOH, and 1 M HCl solution) for 5 months. The samples were also subjected to a combination of temperature and sustained load at room temperature and at 60°C. The glass transition temperature (Tg), storage modulus, tensile strength, and strain at failure were measured. The fracture surface of samples used in the tensile test were examined using a SEM. Results showed that immersion in aging media lowers Tg and enhances apparent phase separation in the samples due to polymer plasticization. At the elevated temperature, the Tg and the stiffness increased owing to continued resin curing. Sustained load, at the level used, had little effect on the mechanical behavior of the aged samples. At room temperature, water had the greatest influence in reducing the stiffness of epoxy neat resin samples. Combined effect of elevated temperature and sustained load caused an increase in Tg and a gain in stiffness in both epoxy neat resin and composite samples. This result is attributed more to the effect of temperature rather than to the effect of sustained load. At room temperature, glass/epoxy composite samples soaked in acid solution showed the highest reduction in tensile strength; this failure was the result of fiber damage. Other composite samples soaked in water and alkali were found to fail by adhesive failure mode. At 60°C, alkali was found to be the most damaging solution to glass/epoxy composite samples in terms of tensile strength. Here the composite samples failed under fiber failure mode while the composite samples soaked in water and acid solution failed under adhesive

  16. Procedural Complexity of the Age Discrimination in Employment Act: An Age-Old Problem.

    ERIC Educational Resources Information Center

    Sheeder, Robert E.

    1980-01-01

    The procedural prerequisites to an Age Discrimination in Employment Act (ADEA) action are examined. The 1978 amendments to the Act as well as the leading decisions involving procedural matters are discussed. Available from The Duquesne Law Review, 901 Rockwell Hall, 600 Forbes Ave., Pittsburgh, PA 15219. (Author/MLF)

  17. Predicting the ageing and the long-term durability of organic polymer solar cells

    NASA Astrophysics Data System (ADS)

    Gardette, Jean-Luc; Rivaton, Agnès; Thérias, Sandrine; Chambon, Sylvain; Manceau, Matthieu; Gaume, Julien

    2010-06-01

    Organic solar cells based on conductive polymers exhibit a unique combination of properties which include low cost, flexibility and large surface processability. Organic photovoltaic could then prevail for some applications alongside silicon, such as nomad or indoor. To achieve this objective, the sustainability of the initial properties in conditions of use of the cell is required, since it could be a lock to the emergence of these devices in the market. The polymers used in solar cells are indeed known to exhibit low resistance to environmental constraints, in particular to the combined action of sunlight, oxygen and water. We present recent results on both the accelerated artificial and the natural outdoors ageing of MDMO-PPV (Poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-Phenylenevinylene) and P3HT/PCBM blends poly(3-hexylthiophene) (P3HT) (methano-fullerene[6,6]-phenyl C61-butyric acid methyl ester) ([60] PCBM). The influence of various parameters such as the temperature and the presence of oxygen were studied. The modifications of the chemical structure of both the components of the blend were monitored by spectroscopic analysis (infrared, UV-visible), the morphology of the blends was analysed by AFM and XRD and the photovoltaic performances all along the exposure were recorded. Two important results have been pointed out: on one hand, the Achilles heel of the chemical structure of MDMO-PPV and P3HT under the impact of light has been evidenced. On the other hand, it has been shown that P3HT:PCBM blends are much more stable than MDMO:PCBM blends whatever the conditions of ageing are. Results show that a convenient encapsulation can ensure a promising lifetime of P3HT/PCBM blends in real conditions of use. This work also focuses on this last point and proposes to study and try to understand the behavior of the materials used in the active layer when submitted to photoaging and thermal aging in the absence of oxygen. To fulfil very good encapsulation, glass

  18. 40 CFR Appendix Viii to Part 86 - Aging Bench Equipment and Procedures

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Aging Bench Equipment and Procedures.... VIII Appendix VIII to Part 86—Aging Bench Equipment and Procedures This appendix provides specifications for standard aging bench equipment and aging procedures which may be used to conduct bench...

  19. 40 CFR 610.33 - Durability tests.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Durability tests. 610.33 Section 610... RETROFIT DEVICES Test Procedures and Evaluation Criteria Test Requirement Criteria § 610.33 Durability tests. The Administrator may determine that a device under evaluation will require durability testing...

  20. 40 CFR 610.33 - Durability tests.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Durability tests. 610.33 Section 610... RETROFIT DEVICES Test Procedures and Evaluation Criteria Test Requirement Criteria § 610.33 Durability tests. The Administrator may determine that a device under evaluation will require durability testing...

  1. 40 CFR 610.33 - Durability tests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Durability tests. 610.33 Section 610... RETROFIT DEVICES Test Procedures and Evaluation Criteria Test Requirement Criteria § 610.33 Durability tests. The Administrator may determine that a device under evaluation will require durability testing...

  2. 40 CFR 610.33 - Durability tests.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Durability tests. 610.33 Section 610... RETROFIT DEVICES Test Procedures and Evaluation Criteria Test Requirement Criteria § 610.33 Durability tests. The Administrator may determine that a device under evaluation will require durability testing...

  3. WOODSTOVE DURABILITY TESTING PROTOCOL

    EPA Science Inventory

    The report discusses the development of an accelerated laboratory test to simulate in-home woodstove aging and degradation. nown as a stress test, the protocol determines the long-term durability of woodstove models in a 1- to 2-week time frame. wo avenues of research have been t...

  4. A facile reflux procedure to increase active surface sites form highly active and durable supported palladium@platinum bimetallic nanodendrites

    NASA Astrophysics Data System (ADS)

    Wang, Qin; Li, Yingjun; Liu, Baocang; Xu, Guangran; Zhang, Geng; Zhao, Qi; Zhang, Jun

    2015-11-01

    A series of well-dispersed bimetallic Pd@Pt nanodendrites uniformly supported on XC-72 carbon black are fabricated by using different capping agents. These capping agents are essential for the branched morphology control. However, the surfactant adsorbed on the nanodendrites surface blocks the access of reactant molecules to the active surface sites, and the catalytic activities of these bimetallic nanodendrites are significantly restricted. Herein, a facile reflux procedure to effectively remove the capping agent molecules without significantly affecting their sizes is reported for activating supported nanocatalysts. More significantly, the structure and morphology of the nanodendrites can also be retained, enhancing the numbers of active surface sites, catalytic activity and stability toward methanol and ethanol electro-oxidation reactions. The as-obtained hot water reflux-treated Pd@Pt/C catalyst manifests superior catalytic activity and stability both in terms of surface and mass specific activities, as compared to the untreated catalysts and the commercial Pt/C and Pd/C catalysts. We anticipate that this effective and facile removal method has more general applicability to highly active nanocatalysts prepared with various surfactants, and should lead to improvements in environmental protection and energy production.

  5. Duct Tape Durability Testing

    SciTech Connect

    Sherman, Max H.; Walker, Iain S.

    2004-04-01

    Duct leakage is a major source of energy loss in residential buildings. Most duct leakage occurs at the connections to registers, plenums, or branches in the duct system. At each of these connections, a method of sealing the duct system is required. Typical sealing methods include tapes or mastics applied around the joints in the system. Field examinations of duct systems have shown that taped seals tend to fail over extended periods of time. The Lawrence Berkeley National Laboratory (LBNL) has been testing sealant durability for several years using accelerated test methods and found that typical duct tape (i.e., cloth-backed tapes with natural rubber adhesives) fails more rapidly than other duct sealants. This report summarizes the results of duct sealant durability testing over two years for four UL 181B-FX listed duct tapes (two cloth tapes, a foil tape and an Oriented Polypropylene (OPP) tape). One of the cloth tapes was specifically developed in collaboration with a tape manufacturer to perform better in our durability testing. The tests involved the aging of common ''core-to-collar joints'' of flexible duct to sheet metal collars. Periodic air leakage tests and visual inspection were used to document changes in sealant performance. After two years of testing, the flex-to-collar connections showed little change in air leakage, but substantial visual degradation from some products. A surprising experimental result was failure of most of the clamps used to mechanically fasten the connections. This indicates that the durability of clamps also need to be addressed ensure longevity of the duct connection. An accelerated test method developed during this study has been used as the basis for an ASTM standard (E2342-03).

  6. Durability of laparoscopic repair of paraesophageal hernia.

    PubMed Central

    Edye, M B; Canin-Endres, J; Gattorno, F; Salky, B A

    1998-01-01

    OBJECTIVES: To define a method of primary repair that would minimize hernia recurrence and to report medium-term follow-up of patients who underwent laparoscopic repair of paraesophageal hernia to verify durability of the repair and to assess the effect of inclusion of an antireflux procedure. SUMMARY BACKGROUND DATA: Primary paraesophageal hernia repair was completed laparoscopically in 55 patients. There were five recurrences within 6 months when the sac was not excised (20%). After institution of a technique of total sac excision in 30 subsequent repairs, no early recurrences were observed. METHODS: Inclusion of an antireflux procedure, incidence of subsequent hernia recurrence, dysphagia, and gastroesophageal reflux symptoms were recorded in clinical follow-up of patients who underwent a laparoscopic procedure. RESULTS: Mean length of follow-up was 29 months. Forty-nine patients were available for follow-up, and one patient had died of lung cancer. Mean age at surgery was 68 years. The surgical morbidity rate in elderly patients was no greater than in younger patients. Eleven patients (22%) had symptoms of mild to moderate reflux, and 15 were taking acid-reduction medication for a variety of dyspeptic complaints. All but 2 of these 15 had undergone 360 degrees fundoplication at initial repair. Two patients (4%) had late recurrent hernia, each small, demonstrated by esophagram or endoscopy. CONCLUSIONS: Laparoscopic repair in the medium term appeared durable. The incidence of postsurgical reflux symptoms was unrelated to inclusion of an antireflux procedure. In the absence of motility data, partial fundoplication was preferred, although dysphagia after floppy 360 degrees wrap was rare. With the low morbidity rate of this procedure, correction of symptomatic paraesophageal hernia appears indicated in patients regardless of age. Images Figure 1. PMID:9790342

  7. On the bubble? With healthcare job growth outstripping population in aging Rust Belt cities, some question the trend's durability.

    PubMed

    Carlson, Joe; Kutscher, Beth

    2013-03-01

    Aging Rust Belt cities are some of the leaders in healthcare job growth despite stagnant or decreasing populations, even amid mounting pressure to cut healthcare costs. Areas seeing rapid population growth aren't as dependent on healthcare. "Cities that are growing quickly are most likely adding diversified industries," says Dr. Sheldon Retchin, of the Virginia Commonwealth University Health System.

  8. AGEING PROCEDURES ON LITHIUM BATTERIES IN AN INTERNATIONAL COLLABORATION CONTEXT

    SciTech Connect

    Jeffrey R. Belt; Ira Bloom; Mario Conte; Fiorentino Valerio Conte; Kenji Morita; Tomohiko Ikeya; Jens Groot

    2010-11-01

    The widespread introduction of electrically-propelled vehicles is currently part of many political strategies and introduction plans. These new vehicles, ranging from limited (mild) hybrid to plug-in hybrid to fully-battery powered, will rely on a new class of advanced storage batteries, such as those based on lithium, to meet different technical and economical targets. The testing of these batteries to determine the performance and life in the various applications is a time-consuming and costly process that is not yet well developed. There are many examples of parallel testing activities that are poorly coordinated, for example, those in Europe, Japan and the US. These costs and efforts may be better leveraged through international collaboration, such as that possible within the framework of the International Energy Agency. Here, a new effort is under development that will establish standardized, accelerated testing procedures and will allow battery testing organizations to cooperate in the analysis of the resulting data. This paper reviews the present state-of-the-art in accelerated life testing in Europe, Japan and the US. The existing test procedures will be collected, compared and analyzed with the goal of international collaboration.

  9. Effect of different light-curing devices and aging procedures on composite knoop microhardness.

    PubMed

    Voltarelli, Fernanda Regina; dos Santos-Daroz, Claudia Batitucci; Alves, Marcelo Corrêa; Peris, Alessandra Rezende; Marchi, Giselle Maria

    2009-01-01

    The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC) and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S) on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s) on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.

  10. Neonatal invasive procedures predict pain intensity at school age in children born very preterm

    PubMed Central

    Valeri, Beatriz Oliveira; Ranger, Manon; Chau, Cecil MY; Cepeda, Ivan L.; Synnes, Anne; Linhares, Maria Beatriz Martins; Grunau, Ruth E.

    2016-01-01

    Children born very preterm display altered pain thresholds. Little is known about neonatal clinical and psychosocial factors associated with their later pain perception. OBJECTIVE We aimed to examine whether the number of neonatal invasive procedures, adjusted for other clinical and psychosocial factors, was associated with self-ratings of pain during a blood collection procedure in children born very preterm at school age. METHODS 56 children born very preterm (24–32 weeks gestational age) at age 7.5 years, followed longitudinally from birth, and free of major neurodevelopmental impairments, underwent a blood collection by venipuncture. The children’s pain was self-reported using the Coloured Analog Scale and Facial Affective Scale. Parents completed the Child Behavior Checklist and State-Trait Anxiety Inventory. Pain exposure (number of invasive procedures) and clinical factors from birth to term-equivalent age were obtained prospectively. Multiple linear regression was used to predict children’s pain self-ratings from neonatal pain exposure after adjusting for neonatal clinical and concurrent psychosocial factors. RESULTS Greater number of neonatal invasive procedures and higher parent trait-anxiety were associated with higher pain intensity ratings during venipuncture at age 7.5 years. Fewer surgeries and lower concurrent child externalizing behaviors were associated with higher pain intensity. CONCLUSION In very preterm children, exposure to neonatal pain was related to altered pain self-ratings at school age, independent of other neonatal factors. Neonatal surgeries and concurrent psychosocial factors were also associated with pain ratings. PMID:26783986

  11. Statistical methods to assess the reliability of measurements in the procedures for forensic age estimation.

    PubMed

    Ferrante, L; Cameriere, R

    2009-07-01

    In forensic science, anthropology, and archaeology, several techniques have been developed to estimate chronological age in both children and adults, using the relationship between age and morphological changes in the structure of teeth. Before implementing a statistical model to describe age as a function of the measured morphological variables, the reliability of the measurements of these variables must be evaluated using suitable statistical methods. This paper introduces some commonly used statistical methods for assessing the reliability of procedures for age estimation in the forensic field. The use of the concordance correlation coefficient and the intraclass correlation coefficient are explained. Finally, some pitfalls in the choice of the statistical methods to assess reliability of the measurements in age estimation are discussed.

  12. A revised burial dose estimation procedure for optical dating of youngand modern-age sediments

    USGS Publications Warehouse

    Arnold, L.J.; Roberts, R.G.; Galbraith, R.F.; DeLong, S.B.

    2009-01-01

    The presence of genuinely zero-age or near-zero-age grains in modern-age and very young samples poses a problem for many existing burial dose estimation procedures used in optical (optically stimulated luminescence, OSL) dating. This difficulty currently necessitates consideration of relatively simplistic and statistically inferior age models. In this study, we investigate the potential for using modified versions of the statistical age models of Galbraith et??al. [Galbraith, R.F., Roberts, R.G., Laslett, G.M., Yoshida, H., Olley, J.M., 1999. Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: Part I, experimental design and statistical models. Archaeometry 41, 339-364.] to provide reliable equivalent dose (De) estimates for young and modern-age samples that display negative, zero or near-zero De estimates. For this purpose, we have revised the original versions of the central and minimum age models, which are based on log-transformed De values, so that they can be applied to un-logged De estimates and their associated absolute standard errors. The suitability of these 'un-logged' age models is tested using a series of known-age fluvial samples deposited within two arroyo systems from the American Southwest. The un-logged age models provide accurate burial doses and final OSL ages for roughly three-quarters of the total number of samples considered in this study. Sensitivity tests reveal that the un-logged versions of the central and minimum age models are capable of producing accurate burial dose estimates for modern-age and very young (<350??yr) fluvial samples that contain (i) more than 20% of well-bleached grains in their De distributions, or (ii) smaller sub-populations of well-bleached grains for which the De values are known with high precision. Our results indicate that the original (log-transformed) versions of the central and minimum age models are still preferable for most routine dating applications

  13. Age and gender disparities in the risk of carotid revascularization procedures.

    PubMed

    Giannopoulos, Sotirios; Katsanos, Aristeidis H; Vasdekis, Spyros N; Boviatsis, Efstathios; Voumvourakis, Konstantinos Iota; Tsivgoulis, Georgios

    2013-10-01

    The potential effect of age and gender stratification in the outcome of patients with carotid artery stenosis undergoing carotid revascularization procedures (CRP) may have important implications in clinical practice. Both European Stroke Organization and American Heart Association guidelines suggest that age and sex should be taken into account when selecting a CRP for an individual patient. We reviewed available literature data through Medline and Embase. Our search was based on the combination of terms: age, gender, sex, carotid artery stenosis, carotid artery stenting (CAS) and carotid endarterectomy (CEA). Postoperative stroke and mortality rates increased with age after any CRP (CEA or CAS), especially in patients aged over 75 years. Older patients with carotid artery stenosis undergoing CAS were found to have a nearly double risk of stroke or death compared with CEA, while CEA was found to benefit more patients aged over 70 years with symptomatic carotid artery stenosis. Male patients with symptomatic or asymptomatic carotid artery stenosis had lower stroke/mortality rates and benefited more from CEA compared with females. For the periprocedural risk of stroke or death in patients with carotid artery stenosis after CAS no sex differences were found. Therefore, CEA appears to have lower perioperative risks than CAS in patients aged over 70 years, and thus should be the treatment of choice if not contraindicated. The periprocedural risk of CEA is lower in men than in women, while there was no effect of gender on the periprocedural risk of CAS.

  14. Age-related changes in the cerebral substrates of cognitive procedural learning.

    PubMed

    Hubert, Valérie; Beaunieux, Hélène; Chételat, Gaël; Platel, Hervé; Landeau, Brigitte; Viader, Fausto; Desgranges, Béatrice; Eustache, Francis

    2009-04-01

    Cognitive procedural learning occurs in three qualitatively different phases (cognitive, associative, and autonomous). At the beginning of this process, numerous cognitive functions are involved, subtended by distinct brain structures such as the prefrontal and parietal cortex and the cerebellum. As the learning progresses, these cognitive components are gradually replaced by psychomotor abilities, reflected by the increasing involvement of the cerebellum, thalamus, and occipital regions. In elderly subjects, although cognitive studies have revealed a learning effect, performance levels differ during the acquisition of a procedure. The effects of age on the learning of a cognitive procedure have not yet been examined using functional imaging. The aim of this study was therefore to characterize the cerebral substrates involved in the learning of a cognitive procedure, comparing a group of older subjects with young controls. For this purpose, we performed a positron emission tomography activation study using the Tower of Toronto task. A direct comparison of the two groups revealed the involvement of a similar network of brain regions at the beginning of learning (cognitive phase). However, the engagement of frontal and cingulate regions persisted in the older group as learning continued, whereas it ceased in the younger controls. We assume that this additional activation in the older group during the associative and autonomous phases reflected compensatory processes and the fact that some older subjects failed to fully automate the procedure. PMID:18537110

  15. Durability of an inorganic polymer concrete coating

    NASA Astrophysics Data System (ADS)

    Wasserman, Kenneth

    The objective of the research program reported in this thesis is to evaluate the durability of an inorganic polymer composite coating exposed to freeze/thaw cycling and wet-dry cycling. Freeze/thaw cycling is performed following ASTM D6944-09 Standard Practice for Resistance of Cured Coatings to Thermal Cycling and wet/dry cycling is performed following guidelines set forth in a thesis written by Ronald Garon at Rutgers University. For both sets of experiments, four coating mixture proportions were evaluated. The variables were: silica/alumina ratio, mixing protocol using high shear and normal shear mixing, curing temperatures of 70 and 120 degrees Fahrenheit and use of nano size constituent materials. The mix with highest silica/alumina ratio was designated as Mix 1 and mixes with lower ratios were designated as Mix 2 and Mix 3. Mix 4 had nano silica particles. Four prisms were used for each variable including control that had no coating. The performance of the coating was evaluated using adhesion strength measured using: ASTM D7234 Test Method for Pull-Off Strength of Coatings on Concrete Using Portable Adhesion Testers. Tests were performed after every five consecutive cycles of thermal conditioning and six consecutive cycles of wet-dry exposure. Results from the thermal cycling and wet-dry testing demonstrate that all coating formulations are durable. The minimum adhesion strength was 300 psi even though a relatively weak base concrete surface was chosen for the study. The weak surface was chosen to simulate aged concrete surfaces present in actual field conditions. Due to the inherent nature of the test procedure the variation in test results is high. However, based on the test results, high shear mixer and high temperature curing are not recommended. As expected nano size constituent materials provide better performance.

  16. Motor Skills Enhance Procedural Memory Formation and Protect against Age-Related Decline.

    PubMed

    Müller, Nils C J; Genzel, Lisa; Konrad, Boris N; Pawlowski, Marcel; Neville, David; Fernández, Guillén; Steiger, Axel; Dresler, Martin

    2016-01-01

    The ability to consolidate procedural memories declines with increasing age. Prior knowledge enhances learning and memory consolidation of novel but related information in various domains. Here, we present evidence that prior motor experience-in our case piano skills-increases procedural learning and has a protective effect against age-related decline for the consolidation of novel but related manual movements. In our main experiment, we tested 128 participants with a sequential finger-tapping motor task during two sessions 24 hours apart. We observed enhanced online learning speed and offline memory consolidation for piano players. Enhanced memory consolidation was driven by a strong effect in older participants, whereas younger participants did not benefit significantly from prior piano experience. In a follow up independent control experiment, this compensatory effect of piano experience was not visible after a brief offline period of 30 minutes, hence requiring an extended consolidation window potentially involving sleep. Through a further control experiment, we rejected the possibility that the decreased effect in younger participants was caused by training saturation. We discuss our results in the context of the neurobiological schema approach and suggest that prior experience has the potential to rescue memory consolidation from age-related cognitive decline. PMID:27333186

  17. Motor Skills Enhance Procedural Memory Formation and Protect against Age-Related Decline

    PubMed Central

    Müller, Nils C. J.; Genzel, Lisa; Konrad, Boris N.; Pawlowski, Marcel; Neville, David; Fernández, Guillén; Steiger, Axel

    2016-01-01

    The ability to consolidate procedural memories declines with increasing age. Prior knowledge enhances learning and memory consolidation of novel but related information in various domains. Here, we present evidence that prior motor experience–in our case piano skills–increases procedural learning and has a protective effect against age-related decline for the consolidation of novel but related manual movements. In our main experiment, we tested 128 participants with a sequential finger-tapping motor task during two sessions 24 hours apart. We observed enhanced online learning speed and offline memory consolidation for piano players. Enhanced memory consolidation was driven by a strong effect in older participants, whereas younger participants did not benefit significantly from prior piano experience. In a follow up independent control experiment, this compensatory effect of piano experience was not visible after a brief offline period of 30 minutes, hence requiring an extended consolidation window potentially involving sleep. Through a further control experiment, we rejected the possibility that the decreased effect in younger participants was caused by training saturation. We discuss our results in the context of the neurobiological schema approach and suggest that prior experience has the potential to rescue memory consolidation from age-related cognitive decline. PMID:27333186

  18. Photovoltaic module performance and durability following long-term field exposure

    SciTech Connect

    Ellibee, D.E.; Hansen, B.R.; King, D.L.; Kratochvil, J.A.; Quintana, M.A.

    1998-09-08

    Our investigations of both new and field-aged photovoltaic modules have indicated that, in general, today's commercially available modules area highly reliable product. However, by using new test procedures, subtle failure mechanisms have also been identified that must be addressed in order to achieve 30-year module lifetimes. This paper summarizes diagnostic test procedures, results, and implications of in-depth investigations of the performance and durability characteristics of commercial modules after long-term field exposure. A collaborative effort with U.S. module manufacturers aimed at achieving 30-year module lifetimes is also described.

  19. Durable metallized polymer mirror

    DOEpatents

    Schissel, Paul O.; Kennedy, Cheryl E.; Jorgensen, Gary J.; Shinton, Yvonne D.; Goggin, Rita M.

    1994-01-01

    A metallized polymer mirror construction having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate.

  20. Durable metallized polymer mirror

    DOEpatents

    Schissel, P.O.; Kennedy, C.E.; Jorgensen, G.J.; Shinton, Y.D.; Goggin, R.M.

    1994-11-01

    A metallized polymer mirror construction is disclosed having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate. 6 figs.

  1. Facile preparation of super durable superhydrophobic materials.

    PubMed

    Wu, Lei; Zhang, Junping; Li, Bucheng; Fan, Ling; Li, Lingxiao; Wang, Aiqin

    2014-10-15

    The low stability, complicated and expensive fabrication procedures seriously hinder practical applications of superhydrophobic materials. Here we report an extremely simple method for preparing super durable superhydrophobic materials, e.g., textiles and sponges, by dip coating in fluoropolymers (FPs). The morphology, surface chemical composition, mechanical, chemical and environmental stabilities of the superhydrophobic textiles were investigated. The results show how simple the preparation of super durable superhydrophobic textiles can be! The superhydrophobic textiles outperform their natural counterparts and most of the state-of-the-art synthetic superhydrophobic materials in stability. The intensive mechanical abrasion, long time immersion in various liquids and repeated washing have no obvious influence on the superhydrophobicity. Water drops are spherical in shape on the samples and could easily roll off after these harsh stability tests. In addition, this simple dip coating approach is applicable to various synthetic and natural textiles and can be easily scaled up. Furthermore, the results prove that a two-tier roughness is helpful but not essential with regard to the creation of super durable superhydrophobic textiles. The combination of microscale roughness of textiles and materials with very low surface tension is enough to form super durable superhydrophobic textiles. According to the same procedure, superhydrophobic polyurethane sponges can be prepared, which show high oil absorbency, oil/water separation efficiency and stability. PMID:25069050

  2. Investigating the Structure of the WJ-III Cognitive in Early School Age through Two Exploratory Bifactor Analysis Procedures

    ERIC Educational Resources Information Center

    Dombrowski, Stefan C.

    2014-01-01

    Two exploratory bifactor methods (e.g., Schmid-Leiman [SL] and exploratory bifactor analysis [EBFA]) were used to investigate the structure of the Woodcock-Johnson III (WJ-III) Cognitive in early school age (age 6-8). The SL procedure is recognized by factor analysts as a preferred method for EBFA. Jennrich and Bentler recently developed an…

  3. Successful conjunctival socket expansion in anophthalmic patients until the age of 2 years: an outpatient procedure

    PubMed Central

    El Essawy, Rania Assem; Abdelbaky, Sameh Hassan

    2016-01-01

    Purpose To report the results of a simple outpatient method for soft tissue socket expansion in young children with congenital anophthalmos. Methods Seventeen congenital anophthalmic sockets of 15 infants of a mean age of 4.2±4.4 months were fitted with specially designed serial solid acrylic shapes or hydrogel expanders using cyanoacrylate for eyelids closure when using the latter. Results At the age of 2 years, the mean horizontal eyelid length increased from a mean of 11.6±4.5 to 19.4±4.6 mm and the volume of the last expander from a mean of 0.6±0.2 to 2.0±0.3 cm2. The specially designed acrylic shapes could be a substitute to the custom-made molds, which require general anesthesia. Conclusion Successful increase in the horizontal eyelid length as well as the conjunctival socket volume could be achieved by a simple outpatient procedure without the need for repeated hospitalization and general anesthesia in these infants.

  4. Successful conjunctival socket expansion in anophthalmic patients until the age of 2 years: an outpatient procedure

    PubMed Central

    El Essawy, Rania Assem; Abdelbaky, Sameh Hassan

    2016-01-01

    Purpose To report the results of a simple outpatient method for soft tissue socket expansion in young children with congenital anophthalmos. Methods Seventeen congenital anophthalmic sockets of 15 infants of a mean age of 4.2±4.4 months were fitted with specially designed serial solid acrylic shapes or hydrogel expanders using cyanoacrylate for eyelids closure when using the latter. Results At the age of 2 years, the mean horizontal eyelid length increased from a mean of 11.6±4.5 to 19.4±4.6 mm and the volume of the last expander from a mean of 0.6±0.2 to 2.0±0.3 cm2. The specially designed acrylic shapes could be a substitute to the custom-made molds, which require general anesthesia. Conclusion Successful increase in the horizontal eyelid length as well as the conjunctival socket volume could be achieved by a simple outpatient procedure without the need for repeated hospitalization and general anesthesia in these infants. PMID:27672305

  5. Durable superoleophobic polypropylene surfaces.

    PubMed

    Brown, Philip S; Bhushan, Bharat

    2016-08-01

    Polypropylene (PP) is a popular plastic material used in consumer packaging. It would be desirable if such plastic containers were liquid repellent and not so easily fouled by their contents. Existing examples of superoleophobic surfaces typically rely on poorly adhered coatings or delicate surface structures, resulting in poor mechanical durability. Here, we report a facile method for creating superoleophobic PP surfaces via incorporation of nanoparticles (NPs) into the polymer surface. A solvent-NP-PP mixture was spin coated at high temperature to achieve the necessary roughness. Such surfaces were further functionalized with fluorosilane to result in a durable, super-repellent surface. They were also found to exhibit some repellency towards shampoos. This method of incorporating NPs into polymer surfaces could also prove useful in improving the anti-bacterial, mechanical and liquid-repellent properties of plastic devices.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'. PMID:27354730

  6. Combustor liner durability analysis

    NASA Technical Reports Server (NTRS)

    Moreno, V.

    1981-01-01

    An 18 month combustor liner durability analysis program was conducted to evaluate the use of advanced three dimensional transient heat transfer and nonlinear stress-strain analyses for modeling the cyclic thermomechanical response of a simulated combustor liner specimen. Cyclic life prediction technology for creep/fatigue interaction is evaluated for a variety of state-of-the-art tools for crack initiation and propagation. The sensitivity of the initiation models to a change in the operating conditions is also assessed.

  7. (Durability of building materials and components)

    SciTech Connect

    Naus, D.J.

    1990-11-27

    The traveler participated in the fourth meeting of RILEM 100-TSL, Techniques for Service Life Prediction,'' and The Fifth International Conference on Durability of Building Materials and Components.'' In addition, the traveler met with staff members at Taywood Engineering Ltd., Electricite de France, and AEA Technology. The meeting pertained to performance of concrete materials in nuclear power plant structures, time variation of concrete material properties, methods for evaluating concrete structures, and modeling to predict the effects of degradation factors on concrete materials. As many of the concrete structures in general civil engineering applications as well as nuclear power plant applications in Europe are aging, there is increasing emphasis on assessing the durability of these structures. Information was provided of direct application to the Structural Aging Program which would not have been available without these visits. Of equal, or possibly more importance, was the individual contacts established at the organizations visited. Each organization was extremely interested in both the approach and scope of the Structural Aging Program and requested that they be informed of progress. The initial steps were taken to cooperate with several of these researchers and this should help the Structural Aging Program keep abreast of related European activities. In summary, information obtained during this trip will benefit the ongoing Structural Aging Program by informing Oak Ridge National Laboratory (ORNL) of the extensive European research programs addressing the durability of concrete structures, and also by forming and strengthening acquaintances with counterparts in other countries, thus enhancing the basis for possible international cooperation.

  8. Durability of waste glass flax fiber reinforced mortar

    SciTech Connect

    Aly, M.; Hashmi, M. S. J.; Olabi, A. G.; Messeiry, M.

    2011-01-17

    The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performance of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.

  9. Analysis of declarative and procedural knowledge in volleyball according to the level of practice and players' age.

    PubMed

    Gil, Alexander; Moreno, M Perla; García-González, Luís; Moreno, Alberto; del Villar, Fernando

    2012-10-01

    The main objective of the research was to analyse the cognitive expertise of volleyball players, according to their level of practice and age, as well as to verify the existing difference in the knowledge of individuals of the same age but with different levels of practice. The study sample was comprised of 535 individuals ages 12 to 16 years. The independent variables were the level of practice, i.e., playing category in training and in competition (Under-14 and Under-16), and the age. The dependent variables were declarative knowledge and procedural knowledge. An analysis of variance was performed to examine the influence of the level of practice on the declarative knowledge and procedural knowledge of the volleyball players in training stages. There were significant differences both in declarative knowledge and in procedural knowledge according to level of practice. Significant differences were also observed between consecutive ages at different levels of practice. These results show that the level of practice in training and competition is a more relevant factor than the change of age in development of specific knowledge of the sport. PMID:23265024

  10. DURABLE GLASS FOR THOUSANDS OF YEARS

    SciTech Connect

    Jantzen, C.

    2009-12-04

    The durability of natural glasses on geological time scales and ancient glasses for thousands of years is well documented. The necessity to predict the durability of high level nuclear waste (HLW) glasses on extended time scales has led to various thermodynamic and kinetic approaches. Advances in the measurement of medium range order (MRO) in glasses has led to the understanding that the molecular structure of a glass, and thus the glass composition, controls the glass durability by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. During the early stages of glass dissolution, a 'gel' layer resembling a membrane forms through which ions exchange between the glass and the leachant. The hydrated gel layer exhibits acid/base properties which are manifested as the pH dependence of the thickness and nature of the gel layer. The gel layer ages into clay or zeolite minerals by Ostwald ripening. Zeolite mineral assemblages (higher pH and Al{sup 3+} rich glasses) may cause the dissolution rate to increase which is undesirable for long-term performance of glass in the environment. Thermodynamic and structural approaches to the prediction of glass durability are compared versus Ostwald ripening.

  11. Low Cost, Durable Seal

    SciTech Connect

    Roberts, George; Parsons, Jason; Friedman, Jake

    2010-12-17

    Seal durability is critical to achieving the 2010 DOE operational life goals for both stationary and transportation PEM fuel cell stacks. The seal material must be chemically and mechanically stable in an environment consisting of aggressive operating temperatures, humidified gases, and acidic membranes. The seal must also be producible at low cost. Currentlyused seal materials do not meet all these requirements. This project developed and demonstrated a high consistency hydrocarbon rubber seal material that was able to meet the DOE technical and cost targets. Significant emphasis was placed on characterization of the material and full scale molding demonstrations.

  12. Mechanically durable superhydrophobic surfaces.

    PubMed

    Verho, Tuukka; Bower, Chris; Andrew, Piers; Franssila, Sami; Ikkala, Olli; Ras, Robin H A

    2011-02-01

    Development of durable non-wetting surfaces is hindered by the fragility of the microscopic roughness features that are necessary for superhydrophobicity. Mechanical wear on superhydrophobic surfaces usually shows as increased sticking of water, leading to loss of non-wettability. Increased wear resistance has been demonstrated by exploiting hierarchical roughness where nanoscale roughness is protected to some degree by large scale features, and avoiding the use of hydrophilic bulk materials is shown to help prevent the formation of hydrophilic defects as a result of wear. Additionally, self-healing hydrophobic layers and roughness patterns have been suggested and demonstrated. Nevertheless, mechanical contact not only causes damage to roughness patterns but also surface contamination, which shortens the lifetime of superhydrophobic surfaces in spite of the self-cleaning effect. The use of photocatalytic effect and reduced electric resistance have been suggested to prevent the accumulation of surface contaminants. Resistance to organic contaminants is more challenging, however, oleophobic surface patterns which are non-wetting to organic liquids have been demonstrated. While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future. PMID:21274919

  13. Mechanically durable superhydrophobic surfaces.

    PubMed

    Verho, Tuukka; Bower, Chris; Andrew, Piers; Franssila, Sami; Ikkala, Olli; Ras, Robin H A

    2011-02-01

    Development of durable non-wetting surfaces is hindered by the fragility of the microscopic roughness features that are necessary for superhydrophobicity. Mechanical wear on superhydrophobic surfaces usually shows as increased sticking of water, leading to loss of non-wettability. Increased wear resistance has been demonstrated by exploiting hierarchical roughness where nanoscale roughness is protected to some degree by large scale features, and avoiding the use of hydrophilic bulk materials is shown to help prevent the formation of hydrophilic defects as a result of wear. Additionally, self-healing hydrophobic layers and roughness patterns have been suggested and demonstrated. Nevertheless, mechanical contact not only causes damage to roughness patterns but also surface contamination, which shortens the lifetime of superhydrophobic surfaces in spite of the self-cleaning effect. The use of photocatalytic effect and reduced electric resistance have been suggested to prevent the accumulation of surface contaminants. Resistance to organic contaminants is more challenging, however, oleophobic surface patterns which are non-wetting to organic liquids have been demonstrated. While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future.

  14. Urban Decline and Durable Housing.

    ERIC Educational Resources Information Center

    Glaeser, Edward L.; Gyourko, Joseph

    2005-01-01

    Urban decline is not the mirror image of growth, and durable housing is the primary reason the nature of decline is so different. This paper presents a model of urban decline with durable housing and verifies these implications of the model: (1) city growth rates are skewed so that cities grow more quickly than they decline; (2) urban decline is…

  15. Durability of carotid endarterectomy.

    PubMed

    Baker, W H; Hayes, A C; Mahler, D; Littooy, F N

    1983-07-01

    Carotid endarterectomy is the preferred treatment for patients with transient ischemic attacks and carotid stenosis. Although clinically these patients do well, the long-term fate of the operated carotid artery has not been well documented. To address this question, repeated noninvasive testing has been employed to follow our carotid endarterectomy patients since 1976. Supraorbital Doppler examination, oculoplethysmography-Kartchner, carotid phonoangiography and, later in this series, spectral analysis of the carotid Doppler velocities were performed after 193 endarterectomies. One hundred fifty-eight patients were initially tested within 3 months of operation, and 35 were initially tested 3 or more months after operation. Twenty-four arteries, four of which were symptomatic, had an initial abnormal test and are excluded from this study of carotid artery durability. Of the 169 patients with normal carotid tests, 36 had no further evaluation. Among the 133 patients who returned for serial testing from 1 to 60 months (mean 20 months), 115 carotid arteries continued to test normal at late follow-up but 18 subsequently developed test abnormalities. Ten had more than 75% stenosis, eight had 50% to 75% stenosis. Eight of these patients had contrast studies: three had normal findings; the five that had abnormal findings underwent reoperation. Interestingly, only two patients presented with symptoms appropriate to the abnormal test. The findings suggest that carotid endarterectomy is a reasonably durable operation. Recurrent stenosis was presumed or proven in 10% of 133 serially tested carotid arteries. This threat of restenosis makes long-term follow-up of these patients mandatory.

  16. Durability of the Malone antegrade continence enema in pregnancy.

    PubMed

    Wren, Francis J; Reese, Carl T; Decter, Ross M

    2003-03-01

    The Malone antegrade continence enema (MACE) is a therapeutic option to treat chronic constipation and fecal incontinence in patients with neurogenic bowel. Previous reports have described the short-term success of this procedure, but no report has described the durability of the procedure during pregnancy. We present the case of a spinal cord injury patient who underwent an uncomplicated pregnancy after a MACE procedure with no stomal catheterization difficulties or leakage during or after the pregnancy.

  17. Effects of aging procedures on the molecular, biochemical, morphological, and mechanical properties of vacuum-formed retainers.

    PubMed

    Ahn, Hyo-Won; Ha, Hye-Ryun; Lim, Ho-Nam; Choi, Samjin

    2015-11-01

    The influence of intraoral exposure procedures on the physical characteristics of thermoplastic vacuum-formed retainers (VFRs) is still unclear. The effects of thermoforming and intraoral use on the molecular, chemical, morphological, and mechanical properties of thermoplastic VFRs were investigated. VFRs with a 0.8-mm-thick thermoplastic PETG sheet acquired from 48 patients were investigated with two aging procedures, including vacuum forming and intraoral exposure, for 2-week and 6-month. Eight evaluating sites for thermoplastic VFRs were assessed with seven analytical techniques. LM, SEM, and AFM microscopic findings showed that the surface characteristics increased with increasing in vivo exposure time (a four-fold increase) and varied depending on the sites evaluated (an occlusal surface). Raman and EDX spectroscopic findings showed that aging procedures led to a significant change in the molecular composition of VFRs, leading to a decrease in the composition rate of carbon (C) and the presence of silicon (Si), phosphorus (P), and calcium (Ca). Compressive strength and tensile tests showed that aging procedures led to a significant increase (P<0.01) in ultimate tensile strength, elastic modulus, the stored energy at a 6-mm deflection (u6 mm), and the compressed load at a 3-mm deflection (σ3 mm). Thermoforming led to a smoother surface and no crystallization of PETG sheets. Intraoral exposure accelerated changes in surface morphology, tensile strength, and elastic modulus of VFRs. This change was site-specific and enhanced with an increase in intraoral exposure time. Therefore, thermoforming and in vivo oral exposure procedures led to the molecular, morphological, and mechanical properties of thermoplastic VFRs.

  18. Background Interference Procedure: A Means of Assessing Neurologic Dysfunction in School-Age Children

    ERIC Educational Resources Information Center

    Kenny, Thomas J.

    1971-01-01

    The Bender Gestalt test incorporating the Background Interference Procedure was administered to three groups of children. The BIP yielded significantly higher scores for the brain damaged group, while the scores of the controls and emotionally disturbed children did not differ. (Author)

  19. Hearing Screening Procedures for Infants and Toddlers, Early Childhood & School Age Children.

    ERIC Educational Resources Information Center

    Minnesota State Dept. of Health, St. Paul.

    This manual describes the screening procedures used to identify infants and children in need of further diagnosis and treatment for hearing loss in Minnesota. It is intended for use by Community Health Service agencies, school health programs, Head Start agencies, and voluntary agencies, and should be used as a post-training reference. Newborn…

  20. Increasing Inferential Comprehension Scores of Intermediate-Age Mildly Retarded Students Using Two Direct Teaching Procedures.

    ERIC Educational Resources Information Center

    Bigler, Joan K.

    1984-01-01

    Inferential comprehension questions requiring eight mildly retarded 9-12 year olds to predict outcome and draw conclusions were asked after reading a story passage and after listening. Performance of all Ss improved from baseline to follow-up assessment. Effectiveness of the two procedures was not significantly different. (Author/CL)

  1. Effect of thermal and irradiation aging simulation procedures on polymer properties

    SciTech Connect

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

    1984-04-01

    Prior to initiating a qualification test on safety-related equipment, the testing sequence for thermal and irradiation aging exposures must be chosen. Likewise, the temperature during irradiation must be selected. Typically, U.S. qualification efforts employ ambient temperature irradiation, while French qualification efforts employ 70/sup 0/C irradiations. For several polymer materials, the influence of the thermal and irradiation aging sequence, as well as the irradiation temperature (ambient versus 70/sup 0/C), has been investigated in preparation for Loss-of-Coolant Accident simulated tests. Ultimate tensile properties at completion of aging are presented for three XLPO and XLPE, five EPR and EPDM, two CSPE (HYPALON), one CPE, one VAMAC, one polydiallylphtalate, and one PPS material. Bend test results at completion of aging are presented for two TEFZEL materials. Permanent set after compression results are presented for three EPR, one VAMAC, one BUNA N, one Silicone, and one Viton material.

  2. Designing durable icephobic surfaces

    PubMed Central

    Golovin, Kevin; Kobaku, Sai P. R.; Lee, Duck Hyun; DiLoreto, Edward T.; Mabry, Joseph M.; Tuteja, Anish

    2016-01-01

    Ice accretion has a negative impact on critical infrastructure, as well as a range of commercial and residential activities. Icephobic surfaces are defined by an ice adhesion strength τice < 100 kPa. However, the passive removal of ice requires much lower values of τice, such as on airplane wings or power lines (τice < 20 kPa). Such low τice values are scarcely reported, and robust coatings that maintain these low values have not been reported previously. We show that, irrespective of material chemistry, by tailoring the cross-link density of different elastomeric coatings and by enabling interfacial slippage, it is possible to systematically design coatings with extremely low ice adhesion (τice < 0.2 kPa). These newfound mechanisms allow for the rational design of icephobic coatings with virtually any desired ice adhesion strength. By using these mechanisms, we fabricate extremely durable coatings that maintain τice < 10 kPa after severe mechanical abrasion, acid/base exposure, 100 icing/deicing cycles, thermal cycling, accelerated corrosion, and exposure to Michigan wintery conditions over several months. PMID:26998520

  3. Designing durable icephobic surfaces.

    PubMed

    Golovin, Kevin; Kobaku, Sai P R; Lee, Duck Hyun; DiLoreto, Edward T; Mabry, Joseph M; Tuteja, Anish

    2016-03-01

    Ice accretion has a negative impact on critical infrastructure, as well as a range of commercial and residential activities. Icephobic surfaces are defined by an ice adhesion strength τice < 100 kPa. However, the passive removal of ice requires much lower values of τice, such as on airplane wings or power lines (τice < 20 kPa). Such low τice values are scarcely reported, and robust coatings that maintain these low values have not been reported previously. We show that, irrespective of material chemistry, by tailoring the cross-link density of different elastomeric coatings and by enabling interfacial slippage, it is possible to systematically design coatings with extremely low ice adhesion (τice < 0.2 kPa). These newfound mechanisms allow for the rational design of icephobic coatings with virtually any desired ice adhesion strength. By using these mechanisms, we fabricate extremely durable coatings that maintain τice < 10 kPa after severe mechanical abrasion, acid/base exposure, 100 icing/deicing cycles, thermal cycling, accelerated corrosion, and exposure to Michigan wintery conditions over several months. PMID:26998520

  4. Age-Related Impairment in the 250-Millisecond Delay Eyeblink Classical Conditioning Procedure in C57BL/6 Mice

    PubMed Central

    Vogel, Richard W.; Ewers, Michael; Ross, Charlene; Gould, Thomas J.; Woodruff-Pak, Diana S.

    2002-01-01

    In this study we tested 4-, 9-, 12-, and 18-month-old C57BL/6 mice in the 250-msec delay eyeblink classical conditioning procedure to study age-related changes in a form of associative learning. The short life expectancy of mice, complete knowledge about the mouse genome, and the availability of transgenic and knock-out mouse models of age-related impairments make the mouse an excellent species for expanding knowledge on the neurobiologically and behaviorally well-characterized eyeblink classical conditioning paradigm. Based on previous research with delay eyeblink conditioning in rabbits and humans, we predicted that mice would be impaired on this cerebellar-dependent associative learning task in middle-age, at ∼9 months. To fully examine age differences in behavior in mice, we used a battery of additional behavioral measures with which to compare young and older mice. These behaviors included the acoustic startle response, prepulse inhibition, rotorod, and the Morris water maze. Mice began to show impairment in cerebellar-dependent tasks such as rotorod and eyeblink conditioning at 9 to 12 months of age. Performance in hippocampally dependent tasks was not impaired in any group, including 18-month-old mice. These results in mice support results in other species, indicating that cerebellar-dependent tasks show age-related deficits earlier in adulthood than do hippocampally dependent tasks. PMID:12359840

  5. Dynamic mechanical thermal analysis of maxillofacial prosthetic elastomers: the effect of different disinfecting aging procedures.

    PubMed

    Eleni, Panagiota N; Krokida, Magdalini K; Polyzois, Gregory L; Gettleman, Lawrence

    2014-05-01

    In this study, dynamic mechanical thermal analysis was used to evaluate the changes that occurred in maxillofacial elastomers subjected to different disinfecting regimens. A commercial polydimethyl siloxane (PDMS) and an experimental chlorinated polyethylene (CPE) were treated with different disinfection procedures for a period that simulates 1 year of clinical service: microwave exposure (D1), hypochlorite solution (D2), neutral soap (D3), and a commercial disinfecting solution (D4). A fifth group was kept in dark storage as control. Dynamic mechanical thermal analysis tests operated in a fixed frequency (1 Hz) over a range of temperatures (-130°C to 20°C for PDMS, -60°C to 120°C for CPE). Loss modulus (G″), storage modulus (G'), and loss factor (tanδ) were recorded as a function of temperature. The obtained glass transition temperature (Tg) values were subjected to statistical analysis. Dynamic mechanical thermal analysis revealed changes in Tg values for both materials, which reflect the possible changes in their chemical and physical structure, after different disinfection procedures. The PDMS and CPE samples seem to have less dense structure maybe because of chain scission reaction that probably occurred during the disinfection procedures. According to statistical analysis, Tg values presented significant changes from the control samples among the different materials and disinfecting procedures. Microwave exposure and hypochlorite solution affect CPE significantly, whereas PDMS exhibited significant changes after being treated with a commercial antimicrobial agent, concerning changes that occurred in Tg. In all cases, Tg values were decreased compared with the untreated samples, which were stiffer, presenting higher Tg and G' values. PMID:24799103

  6. Intermediate Ethanol Blends Catalyst Durability Program

    SciTech Connect

    West, Brian H; Sluder, Scott; Knoll, Keith; Orban, John; Feng, Jingyu

    2012-02-01

    In the summer of 2007, the U.S. Department of Energy (DOE) initiated a test program to evaluate the potential impacts of intermediate ethanol blends (also known as mid-level blends) on legacy vehicles and other engines. The purpose of the test program was to develop information important to assessing the viability of using intermediate blends as a contributor to meeting national goals for the use of renewable fuels. Through a wide range of experimental activities, DOE is evaluating the effects of E15 and E20 - gasoline blended with 15% and 20% ethanol - on tailpipe and evaporative emissions, catalyst and engine durability, vehicle driveability, engine operability, and vehicle and engine materials. This report provides the results of the catalyst durability study, a substantial part of the overall test program. Results from additional projects will be reported separately. The principal purpose of the catalyst durability study was to investigate the effects of adding up to 20% ethanol to gasoline on the durability of catalysts and other aspects of the emissions control systems of vehicles. Section 1 provides further information about the purpose and context of the study. Section 2 describes the experimental approach for the test program, including vehicle selection, aging and emissions test cycle, fuel selection, and data handling and analysis. Section 3 summarizes the effects of the ethanol blends on emissions and fuel economy of the test vehicles. Section 4 summarizes notable unscheduled maintenance and testing issues experienced during the program. The appendixes provide additional detail about the statistical models used in the analysis, detailed statistical analyses, and detailed vehicle specifications.

  7. Evidence for a little ice age and recent warming from a borehole temperature data inversion procedure

    SciTech Connect

    Fivez, J.; Thoen, J.

    2004-11-15

    In this article, we apply our analytical theory, published earlier in this journal, to obtain information on the earth surface temperature history from some borehole temperature data. Compared to the results of the five different methods applied to the same temperature data, our method seems to be easier, assumption-free, and yields internally consistent results. The results suggest a cooling a few centuries ago, followed by a continuing warming up to these days, in agreement with a little ice age scenario.

  8. Older Age at Completion of Fontan Procedure Is Associated with Improved Percentage of Predicted Maximum Oxygen Uptake

    PubMed Central

    Maskatia, Shiraz A.; Tate, Amanda L.; Petit, Christopher J.

    2015-01-01

    We tested the hypothesis that later completion of the Fontan procedure is associated with improved exercise capacity in the current period of staged single-ventricle palliation. We performed a retrospective study, in Fontan patients, of exercise stress test data from April 2003 through March 2011. Patients were included if they had received staged palliations in accordance with current surgical strategy, defined as the performance of a superior cavopulmonary connection at ≤1 year of age, followed in subsequent years by Fontan completion. Patients with a pacemaker or respiratory exchange ratio <1 were excluded. Early and late Fontan groups were created on the basis of whether Fontan completion had been performed at <4 or ≥ 4 years of age. The primary predictor variable was age at Fontan completion, and the primary marker of exercise performance was the percentage of predicted maximum oxygen consumption. During the study period, 55 patients were identified (mean age, 11.7 ± 2.8 yr). Older age at Fontan completion correlated positively with higher percentages of predicted maximum oxygen consumption (R=0.286, P=0.034). Patients in whom Fontan completion was performed at ≥4 years of age had higher percentages of predicted maximum oxygen consumption than did those in whom completion was at <4 years of age (84.4 ± 21.5 vs 72.9 ± 18.1; P=0.041). Later Fontan completion might be associated with improved exercise capacity in patients palliated in accordance with contemporary surgical strategy. PMID:26413015

  9. Older Age at Completion of Fontan Procedure Is Associated with Improved Percentage of Predicted Maximum Oxygen Uptake.

    PubMed

    Bolin, Elijah H; Maskatia, Shiraz A; Tate, Amanda L; Petit, Christopher J

    2015-08-01

    We tested the hypothesis that later completion of the Fontan procedure is associated with improved exercise capacity in the current period of staged single-ventricle palliation. We performed a retrospective study, in Fontan patients, of exercise stress test data from April 2003 through March 2011. Patients were included if they had received staged palliations in accordance with current surgical strategy, defined as the performance of a superior cavopulmonary connection at ≤1 year of age, followed in subsequent years by Fontan completion. Patients with a pacemaker or respiratory exchange ratio <1 were excluded. Early and late Fontan groups were created on the basis of whether Fontan completion had been performed at <4 or ≥ 4 years of age. The primary predictor variable was age at Fontan completion, and the primary marker of exercise performance was the percentage of predicted maximum oxygen consumption. During the study period, 55 patients were identified (mean age, 11.7 ± 2.8 yr). Older age at Fontan completion correlated positively with higher percentages of predicted maximum oxygen consumption (R=0.286, P=0.034). Patients in whom Fontan completion was performed at ≥4 years of age had higher percentages of predicted maximum oxygen consumption than did those in whom completion was at <4 years of age (84.4 ± 21.5 vs 72.9 ± 18.1; P=0.041). Later Fontan completion might be associated with improved exercise capacity in patients palliated in accordance with contemporary surgical strategy. PMID:26413015

  10. PEM fuel cell durability studies

    SciTech Connect

    Borup, Rodney L; Davey, John R; Ofstad, Axel B; Xu, Hui

    2008-01-01

    The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization for stationary and transportation power applications. For transportation applications, the durability target for fuel cell power systems is a 5,000 hour lifespan and able to function over a range of vehicle operating conditions (-40{sup o} to +40{sup o}C). However, durability is difficult to quantify and improve because of the quantity and duration of testing required, and also because the fuel cell stack contains many components, for which the degradation mechanisms, component interactions and effects of operating conditions are not fully understood. These requirements have led to the development of accelerated testing protocols for PEM fuel cells. The need for accelerated testing methodology is exemplified by the times required for standard testing to reach their required targets: automotive 5,000 hrs = {approx} 7 months; stationary systems 40,000 hrs = {approx} 4.6 years. As new materials continue to be developed, the need for relevant accelerated testing increases. In this investigation, we examine the durability of various cell components, examine the effect of transportation operating conditions (potential cycling, variable RH, shut-down/start-up, freeze/thaw) and evaluate durability by accelerated durability protocols. PEM fuel cell durability testing is performed on single cells, with tests being conducted with steady-state conditions and with dynamic conditions using power cycling to simulate a vehicle drive cycle. Component and single-cell characterization during and after testing was conducted to identify changes in material properties and related failure mechanisms. Accelerated-testing experiments were applied to further examine material degradation.

  11. Durably controlling bovine hypodermosis.

    PubMed

    Boulard, Chantal

    2002-01-01

    Cattle hypodermosis, due to insect larvae, is widely spread over the northern hemisphere. Very efficient insecticides are available and their use in most countries are done on an individual level but never cover the whole cattle population of a country. Untreated animals remain the reservoir of the disease and annually re-infest the cattle population. The economic effects of this disease on animal production (meat, milk and the leather industry) but also on the general cattle health status, have led many European countries to launch organised control programs. The first example of definitive hypodermosis control goes back one hundred years ago when Danish farmers eradicated hypodermosis from the Danish islands by manual elimination of the warbles. Since then, more and more European countries have considered the feasibility and economic returns of such programs. The various factors which foster these programs are related to (i) biological factors, (parasite cattle specificity, synchronous biological cycles of both species of insects involved), (ii) the development of more and more efficient insecticides used only once a year by systemic application, with high efficiency at very low dosages against the first larval stage of Hypoderma spp., (iii) the development of acute techniques of detection of the disease for the monitoring of hypodermosis free countries and (iv) the durable successful results obtained in more and more European countries. Although the programs were imposed by different partners of the livestock channel production (farmers, dairy industry, leather industry) and have been engaged within the last 50 years in many European countries (Denmark, The Netherlands, Ireland, the United Kingdom, the Czech Republic, Germany, France and Switzerland) common features have emerged among these different eradication programs. They all need a preliminary statement of the economic impact of this pest and the farmers' awareness of the economic returns of such programs

  12. Refreshing the Aged Latent Fingerprints with Ionizing Radiation Prior to the Cyanoacrylate Fuming Procedure: A Preliminary Study.

    PubMed

    Ristova, Mimoza M; Radiceska, Pavlina; Bozinov, Igorco; Barandovski, Lambe

    2016-05-01

    One of the crucial factors determining the cyanoacrylate deposit quality over latent fingerprints appeared to be the extent of the humidity. This work focuses on the enhancement/refreshment of age-degraded latent fingerprints by irradiating the samples with UV, X-ray, or thermal neutrons prior to the cyanoacrylate (CA) fuming. Age degradation of latent fingerprints deposited on glass surfaces was examined through the decrease in the number of characteristic minutiae counts over time. A term "critical day" was introduced for the time at which the average number of identifiable minutiae definitions drops to one-half. Fingerprints older than their "critical day" were exposed to either UV, X-ray, or thermal neutrons. Identical reference samples were kept unexposed. All samples, both reference and irradiated, were developed during a single CA fuming procedure. Comparative latent fingerprint analysis showed that exposure to ionizing radiation enhances the CA fuming, yielding a 20-30% increase in average minutiae count. PMID:27122421

  13. Refreshing the Aged Latent Fingerprints with Ionizing Radiation Prior to the Cyanoacrylate Fuming Procedure: A Preliminary Study.

    PubMed

    Ristova, Mimoza M; Radiceska, Pavlina; Bozinov, Igorco; Barandovski, Lambe

    2016-05-01

    One of the crucial factors determining the cyanoacrylate deposit quality over latent fingerprints appeared to be the extent of the humidity. This work focuses on the enhancement/refreshment of age-degraded latent fingerprints by irradiating the samples with UV, X-ray, or thermal neutrons prior to the cyanoacrylate (CA) fuming. Age degradation of latent fingerprints deposited on glass surfaces was examined through the decrease in the number of characteristic minutiae counts over time. A term "critical day" was introduced for the time at which the average number of identifiable minutiae definitions drops to one-half. Fingerprints older than their "critical day" were exposed to either UV, X-ray, or thermal neutrons. Identical reference samples were kept unexposed. All samples, both reference and irradiated, were developed during a single CA fuming procedure. Comparative latent fingerprint analysis showed that exposure to ionizing radiation enhances the CA fuming, yielding a 20-30% increase in average minutiae count.

  14. Play and video effects on mood and procedure behaviors in school-aged children visiting the pediatrician.

    PubMed

    Burns-Nader, Sherwood; Hernandez-Reif, Maria; Thoma, Stephen J

    2013-10-01

    This study examines how different types of activities, including medical play, typical play, and videos, affect the mood and behaviors of children visiting a pediatric office. Seventy-two school-aged children visiting a pediatrician's office were randomly assigned to 1 of 4 groups: medical play, medical information video, typical play, and nonmedical information video control. Children completed a mood self-report measure and their behaviors were recorded during triage by nurses. The medical information video improved the school-aged children's mood. Children in the medical information video displayed less difficult behaviors during procedures than the medical play group. The findings suggest that providing information about medical equipment through a video of a child engaging in medical play may benefit children visiting the pediatrician.

  15. Developmental Changes in Accommodation Evidenced by an Ultrabiomicroscopy Procedure in Patients of Different Ages

    PubMed Central

    Benozzi, Giovanna; Leiro, Juliana; Facal, Sonia; Perez, Cristian; Benozzi, Jorge; Orman, Betina

    2013-01-01

    We demonstrate that changes in the behaviour of the contractile ciliary muscle accompanied by augmented rigidity of the lens are the most important aspects in the loss of accommodation. With ultrabiomicroscopy (UBM), we demonstrated that the performance of the ciliary muscle is diminished and accompanied by rigidity of the lens. Both lens thickness and trabecular-ciliary process distance (TCPD) were the parameters that showed major alterations with the loss of accommodation in patients of different ages. The results indicated that the differences between these parameters in farsightedness and nearsightedness in the different groups of patients were positively correlated. PMID:24600634

  16. Durable silver coating for mirrors

    DOEpatents

    Wolfe, Jesse D.; Thomas, Norman L.

    2000-01-01

    A durable multilayer mirror includes reflective layers of aluminum and silver and has high reflectance over a broad spectral range from ultraviolet to visible to infrared. An adhesion layer of a nickel and/or chromium alloy or nitride is deposited on an aluminum surface, and a thin layer of silver is then deposited on the adhesion layer. The silver layer is protected by a passivation layer of a nickel and/or chromium alloy or nitride and by one or more durability layers made of metal oxides and typically a first layer of metal nitride. The durability layers may include a composite silicon aluminum nitride and an oxinitride transition layer to improve bonding between nitride and oxide layers.

  17. Enhanced stress durability of nano resonators with scandium doped electrodes

    SciTech Connect

    Nuessl, R.; Jewula, T.; Binninger, C.; Drozd, R.; Ruile, W.; Beckmeier, D.; Sulima, T.; Eisele, I.; Hansch, W.

    2010-11-15

    To explore mechanical stress durability of thin aluminum-scandium (AlSc) films, 0.86 GHz nano resonators with AlSc electrodes have been manufactured. Four different samples have been prepared altering the Sc content in the alloy between 0.0% and 2.5%. A final lift-off step accomplished manufacture procedure of the devices. The resonators have been operated with heavy load to determine power durability. The resonators with AlSc electrodes show increased power durability compared to conventional Al metallized devices. Texture and grain structure of all films have been investigated by means of electron backscatter diffraction (EBSD) and atomic force microscopy (AFM). Material fatigue of electrodes has been visualized by scanning electron microscopy (SEM). The refined grain structure of these alloys can explain the enhanced mechanical stress durability of AlSc electrodes. - Research Highlights: {yields}Enhanced power durability of SAW devices with Sc doped electrodes. {yields}Refined grain structure of Sc doped Al films. {yields}Sudden device breakdown of highly Sc doped devices.

  18. DURABILITY TESTING OF FLUIDIZED BED STEAM REFORMER (FBSR) WASTE FORMS

    SciTech Connect

    Jantzen, C

    2006-01-06

    Fluidized Bed Steam Reforming (FBSR) is being considered as a potential technology for the immobilization of a wide variety of high sodium aqueous radioactive wastes. The addition of clay and a catalyst as co-reactants converts high sodium aqueous low activity wastes (LAW) such as those existing at the Hanford and Idaho DOE sites to a granular ''mineralized'' waste form that may be made into a monolith form if necessary. Simulant Hanford and Idaho high sodium wastes were processed in a pilot scale FBSR at Science Applications International Corporation (SAIC) Science and Technology Applications Research (STAR) facility in Idaho Falls, ID. Granular mineral waste forms were made from (1) a basic Hanford Envelope A low-activity waste (LAW) simulant and (2) an acidic INL simulant commonly referred to as sodium-bearing waste (SBW). The FBSR waste forms were characterized and the durability tested via ASTM C1285 (Product Consistency Test), the Environmental Protection Agency (EPA) Toxic Characteristic Leaching Procedure (TCLP), and the Single Pass Flow Through (SPFT) test. The durability of the FBSR waste form products was tested in order to compare the measured durability to previous FBSR waste form testing on Hanford Envelope C waste forms that were made by THOR Treatment Technologies (TTT) and to compare the FBSR durability to vitreous LAW waste forms, specifically the Hanford low activity waste (LAW) glass known as the Low-activity Reference Material (LRM). The durability of the FBSR waste form is comparable to that of the LRM glass for the test responses studied.

  19. A critical review of the durability of adhesion to tooth tissue: methods and results.

    PubMed

    De Munck, J; Van Landuyt, K; Peumans, M; Poitevin, A; Lambrechts, P; Braem, M; Van Meerbeek, B

    2005-02-01

    The immediate bonding effectiveness of contemporary adhesives is quite favorable, regardless of the approach used. In the long term, the bonding effectiveness of some adhesives drops dramatically, whereas the bond strengths of other adhesives are more stable. This review examines the fundamental processes that cause the adhesion of biomaterials to enamel and dentin to degrade with time. Non-carious class V clinical trials remain the ultimate test method for the assessment of bonding effectiveness, but in addition to being high-cost, they are time- and labor-consuming, and they provide little information on the true cause of clinical failure. Therefore, several laboratory protocols were developed to predict bond durability. This paper critically appraises methodologies that focus on chemical degradation patterns of hydrolysis and elution of interface components, as well as mechanically oriented test set-ups, such as fatigue and fracture toughness measurements. A correlation of in vitro and in vivo data revealed that, currently, the most validated method to assess adhesion durability involves aging of micro-specimens of biomaterials bonded to either enamel or dentin. After about 3 months, all classes of adhesives exhibited mechanical and morphological evidence of degradation that resembles in vivo aging effects. A comparison of contemporary adhesives revealed that the three-step etch-and-rinse adhesives remain the 'gold standard' in terms of durability. Any kind of simplification in the clinical application procedure results in loss of bonding effectiveness. Only the two-step self-etch adhesives approach the gold standard and do have some additional clinical benefits.

  20. Cortisol levels in former preterm children at school age are predicted by neonatal procedural pain-related stress.

    PubMed

    Brummelte, Susanne; Chau, Cecil M Y; Cepeda, Ivan L; Degenhardt, Amanda; Weinberg, Joanne; Synnes, Anne R; Grunau, Ruth E

    2015-01-01

    Early life stress can alter hypothalamic pituitary adrenal (HPA) axis function. Differences in cortisol levels have been found in preterm infants exposed to substantial procedural stress during neonatal intensive care, compared to infants born full-term, but only a few studies investigated whether altered programming of the HPA axis persists past toddler age. Further, there is a dearth of knowledge of what may contribute to these changes in cortisol. This prospective cohort study examined the cortisol profiles in response to the stress of cognitive assessment, as well as the diurnal rhythm of cortisol, in children (n=129) born at varying levels of prematurity (24-32 weeks gestation) and at full-term (38-41 weeks gestation), at age 7 years. Further, we investigated the relationships among cortisol levels and neonatal procedural pain-related stress (controlling for multiple medical confounders), concurrent maternal factors (parenting stress, depressive and anxiety symptoms) and children's behavioral problems. For each aim we investigate acute cortisol response profiles to a cognitive challenge as well as diurnal cortisol patterns at home. We hypothesized that children born very preterm will differ in their pattern of cortisol secretion from children born full-term, possibly depended on concurrent child and maternal factors, and that exposure to neonatal pain-related stress would be associated with altered cortisol secretion in children born very preterm, possibly in a sex-dependent way. Saliva samples were collected from 7-year old children three times during a laboratory visit for assessment of cognitive and executive functions (pretest, mid-test, end-study day acute stress profile) and at four times over two consecutive non-school days at home (i.e. morning, mid-morning, afternoon and bedtime-diurnal rhythm profile). We found that cortisol profiles were similar in preterm and full-term children, albeit preterms had slightly higher cortisol at bedtime compared to

  1. Cortisol levels in former preterm children at school age are predicted by neonatal procedural pain-related stress

    PubMed Central

    Brummelte, Susanne; Chau, Cecil MY; Cepeda, Ivan L.; Degenhardt, Amanda; Weinberg, Joanne; Synnes, Anne R.; Grunau, Ruth E.

    2014-01-01

    Summary Early life stress can alter hypothalamic pituitary adrenal (HPA) axis function. Differences in cortisol levels have been found in preterm infants exposed to substantial procedural stress during neonatal intensive care, compared to infants born full-term, but only a few studies investigated whether altered programming of the HPA axis persists past toddler age. Further, there is a dearth of knowledge of what may contribute to these changes in cortisol. This prospective cohort study examined the cortisol profiles in response to the stress of cognitive assessment, as well as the diurnal rhythm of cortisol, in children (n=129) born at varying levels of prematurity (24–32 weeks gestation) and at full-term (38–41 weeks gestation), at age 7 years. Further, we investigated the relationships among cortisol levels and neonatal procedural pain-related stress (controlling for multiple medical confounders), concurrent maternal factors (parenting stress, depressive and anxiety symptoms) and children’s behavioral problems. For each aim we investigate acute cortisol response profiles to a cognitive challenge as well as diurnal cortisol patterns at home. We hypothesized that children born very preterm will differ in their pattern of cortisol secretion from children born full-term, possibly depended on concurrent child and maternal factors, and that exposure to neonatal pain-related stress would be associated with altered cortisol secretion in children born very preterm, possibly in a sex-dependent way. Saliva samples were collected from 7-year old children three times during a laboratory visit for assessment of cognitive and executive functions (pretest, mid-test, end - study day acute stress profile) and at four times over two consecutive non-school days at home (i.e. morning, mid-morning, afternoon and bedtime - diurnal rhythm profile). We found that cortisol profiles were similar in preterm and full-term children, albeit preterms had slightly higher cortisol at

  2. Cortisol levels in former preterm children at school age are predicted by neonatal procedural pain-related stress.

    PubMed

    Brummelte, Susanne; Chau, Cecil M Y; Cepeda, Ivan L; Degenhardt, Amanda; Weinberg, Joanne; Synnes, Anne R; Grunau, Ruth E

    2015-01-01

    Early life stress can alter hypothalamic pituitary adrenal (HPA) axis function. Differences in cortisol levels have been found in preterm infants exposed to substantial procedural stress during neonatal intensive care, compared to infants born full-term, but only a few studies investigated whether altered programming of the HPA axis persists past toddler age. Further, there is a dearth of knowledge of what may contribute to these changes in cortisol. This prospective cohort study examined the cortisol profiles in response to the stress of cognitive assessment, as well as the diurnal rhythm of cortisol, in children (n=129) born at varying levels of prematurity (24-32 weeks gestation) and at full-term (38-41 weeks gestation), at age 7 years. Further, we investigated the relationships among cortisol levels and neonatal procedural pain-related stress (controlling for multiple medical confounders), concurrent maternal factors (parenting stress, depressive and anxiety symptoms) and children's behavioral problems. For each aim we investigate acute cortisol response profiles to a cognitive challenge as well as diurnal cortisol patterns at home. We hypothesized that children born very preterm will differ in their pattern of cortisol secretion from children born full-term, possibly depended on concurrent child and maternal factors, and that exposure to neonatal pain-related stress would be associated with altered cortisol secretion in children born very preterm, possibly in a sex-dependent way. Saliva samples were collected from 7-year old children three times during a laboratory visit for assessment of cognitive and executive functions (pretest, mid-test, end-study day acute stress profile) and at four times over two consecutive non-school days at home (i.e. morning, mid-morning, afternoon and bedtime-diurnal rhythm profile). We found that cortisol profiles were similar in preterm and full-term children, albeit preterms had slightly higher cortisol at bedtime compared to

  3. Compositional threshold for Nuclear Waste Glass Durability

    SciTech Connect

    Kruger, Albert A.; Farooqi, Rahmatullah; Hrma, Pavel R.

    2013-04-24

    Within the composition space of glasses, a distinct threshold appears to exist that separates "good" glasses, i.e., those which are sufficiently durable, from "bad" glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region.

  4. The use of oral sucrose for procedural pain relief in infants up to six months of age: a randomized controlled trial.

    PubMed

    Wilson, Sally; Bremner, Alexandra P; Mathews, Judy; Pearson, Diane

    2013-12-01

    The aim of this study was to evaluate the effectiveness of oral sucrose in decreasing pain during minor procedures in infants of 1-6 months corrected age. A blinded randomized controlled trial with infants aged 4-26 weeks who underwent venipuncture, heel lance or intravenous cannulation were stratified by corrected age into > 4-12 weeks and > 12-26 weeks. They received 2 mL of either 25% sucrose or sterile water orally 2 minutes before the painful procedure. Nonnutritional sucking and parental comfort, provided in adherence to hospital guidelines, were recorded. Pain behavior was recorded using a validated 10 point scale at baseline, during and following the procedure. Data collectors were blinded to the intervention. A total of 21 and 20 infants received sucrose and water, respectively, in the > 4-12-week age group, and 21 and 22, respectively, in the > 12-26-week age group. No statistical differences were found in pain scores between treatment and control groups at any data collection points in either age group. Infants aged > 4-12 weeks who did nonnutritional sucking showed statistically significantly lower median pain scores at 1, 2, and 3 minutes after the procedure than those who did not suck. Infants aged > 4-26 weeks exhibited pain behavior scores that indicated moderate to large pain during painful procedures; however, there was insufficient evidence to show that 2 mL 25% sucrose had a statistically significant effect in decreasing pain. Infants should be offered nonnutritional sucking in compliance with the Baby Friendly Health Initiative during painful procedures.

  5. CODSTRAN: Composite durability structural analysis

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Smith, G. T.

    1978-01-01

    CODSTRAN (COmposite Durability STRuctural ANalysis) is an integrated computer program being developed for the prediction of defect growth and fracture of composite structures subjected to service loads and environments. CODSTRAN is briefly described with respect to organization, capabilities and present status. Application of CODSTRAN current capability to a flat composite laminate with a center slit which was subjected to axial tension loading predicted defect growth which is in good agreement with C-scan ultrasonic test records.

  6. Durable antistatic coating for polymethylmethacrylate

    NASA Technical Reports Server (NTRS)

    Hadek, V.; Somoano, R. B.; Rembaum, A. (Inventor)

    1977-01-01

    A durable antistatic coating is achieved on polymethylmethacrylate plastic without affecting its optical clarity by applying to the surface of the plastic a low molecular weight solvent having a high electron affinity and a high dipole moment, such as acentonitrile or nitromethane alone or in the presence of photopolymerizable monomer. The treated polymethylmethacrylate plastic dissipates most of the induced electrostatic charge and retains its optical clarity. The antistatic behavior persists after washing, rubbing and vacuum treatment.

  7. Effect of glass composition on waste form durability: A critical review

    SciTech Connect

    Ellison, A.J.G.; Mazer, J.J.; Ebert, W.L.

    1994-11-01

    This report reviews literature concerning the relationship between the composition and durability of silicate glasses, particularly glasses proposed for immobilization of radioactive waste. Standard procedures used to perform durability tests are reviewed. It is shown that tests in which a low-surface area sample is brought into contact with a very large volume of solution provide the most accurate measure of the intrinsic durability of a glass composition, whereas high-surface area/low-solution volume tests are a better measure of the response of a glass to changes in solution chemistry induced by a buildup of glass corrosion products. The structural chemistry of silicate and borosilicate glasses is reviewed to identify those components with the strongest cation-anion bonds. A number of examples are discussed in which two or more cations engage in mutual bonding interactions that result in minima or maxima in the rheologic and thermodynamic properties of the glasses at or near particular optimal compositions. It is shown that in simple glass-forming systems such interactions generally enhance the durability of glasses. Moreover, it is shown that experimental results obtained for simple systems can be used to account for durability rankings of much more complex waste glass compositions. Models that purport to predict the rate of corrosion of glasses in short-term durability tests are evaluated using a database of short-term durability test results for a large set of glass compositions. The predictions of these models correlate with the measured durabilities of the glasses when considered in large groupings, but no model evaluated in this review provides accurate estimates of durability for individual glass compositions. Use of these models in long-term durability models is discussed. 230 refs.

  8. 40 CFR 86.1829-15 - Durability and emission testing requirements; waivers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...). (f) For electric vehicles and fuel cell vehicles, manufacturers may provide a statement in the... emission standards: (1) Test one EDV in each durability group using the test procedures in 40 CFR part 1066... EDV in each test group using the FTP and SFTP test procedures in 40 CFR part 1066 and the HFET...

  9. Durability Improvements Through Degradation Mechanism Studies

    SciTech Connect

    Borup, Rodney L.; Mukundan, Rangachary; Spernjak, Dusan; Baker, Andrew M.; Lujan, Roger W.; Langlois, David Alan; Ahluwalia, Rajesh; Papadia, D. D.; Weber, Adam Z.; Kusoglu, Ahmet; Shi, Shouwnen; More, K. L.; Grot, Steve

    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.

  10. Moisture Durability with Vapor-Permeable Insulating Sheathing

    SciTech Connect

    Lepage, R.; Lstiburek, J.

    2013-09-01

    Exterior sheathing insulation is an effective strategy in increasing the overall R-value of wall assemblies; other benefits include decreasing the effects of thermal bridging and increasing the moisture durability of the built assembly. Vapor-permeable exterior insulation, such as mineral board or expanded polystyrene foam, are one such product that may be used to achieve these benefits. However, uncertainty exists on the effects of inward driven moisture and the interaction of increased sheathing temperatures on the moisture durability of the edifice. To address these concerns, Building Science Corporation (BSC) conducted a series of hygrothermal models for cities representing a range of different climate zones. This report describes the research project, key research questions, and the procedures utilized to analyse the problems.

  11. Environmental Durability of Electroplated Black Chromium

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1983-01-01

    Report describes tests of durability of electroplated black chromium coatings on solar-collector panels in rural, industrial, and seacoast environments for 60, 36, and 13 months, respectively. Black-chromium coating showed exceptionally-good optical durability in all three environments.

  12. 40 CFR 1065.415 - Durability demonstration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Durability demonstration. 1065.415 Section 1065.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION.... Evenly space any tests between the first and last test points throughout the durability period, unless...

  13. 40 CFR 1065.415 - Durability demonstration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Durability demonstration. 1065.415 Section 1065.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION.... Evenly space any tests between the first and last test points throughout the durability period, unless...

  14. Enduring Legacy? Charles Tilly and Durable Inequality

    PubMed Central

    2010-01-01

    This article assesses Charles Tilly’s Durable Inequality and traces its influence. In writing Durable Inequality, Tilly sought to shift the research agenda of stratification scholars. But the book’s initial impact was disappointing. In recent years, however, its influence has grown, suggesting a more enduring legacy. PMID:21258635

  15. 14 CFR 33.19 - Durability.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Durability. 33.19 Section 33.19 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; General § 33.19 Durability. (a) Engine design and construction must minimize the development of...

  16. Ceramics: Durability and radiation effects

    SciTech Connect

    Ewing, R.C.; Lutze, W.; Weber, W.J.

    1996-05-01

    At present, there are three seriously considered options for the disposition of excess weapons plutonium: (1) incorporation, partial burn-up and direct disposal of MOX-fuel; (2) vitrification with defense waste and disposal as glass {open_quotes}logs{close_quotes}; (3) deep borehole disposal. The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, zirconolite, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.

  17. Development of a high-temperature durable catalyst for use in catalytic combustors for advanced automotive gas turbine engines

    NASA Technical Reports Server (NTRS)

    Tong, H.; Snow, G. C.; Chu, E. K.; Chang, R. L. S.; Angwin, M. J.; Pessagno, S. L.

    1981-01-01

    Durable catalytic reactors for advanced gas turbine engines were developed. Objectives were: to evaluate furnace aging as a cost effective catalytic reactor screening test, measure reactor degradation as a function of furnace aging, demonstrate 1,000 hours of combustion durability, and define a catalytic reactor system with a high probability of successful integration into an automotive gas turbine engine. Fourteen different catalytic reactor concepts were evaluated, leading to the selection of one for a durability combustion test with diesel fuel for combustion conditions. Eight additional catalytic reactors were evaluated and one of these was successfully combustion tested on propane fuel. This durability reactor used graded cell honeycombs and a combination of noble metal and metal oxide catalysts. The reactor was catalytically active and structurally sound at the end of the durability test.

  18. Permanence and durability of digital prints on paper

    NASA Astrophysics Data System (ADS)

    Černič, M.; Dolenc, J.; Scheicher, L.

    2006-06-01

    The paper used as a printing substrate in electro photographical techniques should achieve appropriate structure, surface and optical properties as well as thermal stability. Printing products are often exposed to negative influence from external climate conditions. Surface treatment with varnishing and lamination is a common solution for protecting the final products against light, higher temperatures and elevated relative humidity. In the context of the applied research done in cooperation with the printing industry we studied permanence and durability of paper, image of prints and final printed product. We were also examining the influence of accelerated artificial ageing of paper and colour prints in electro photographic printing technique (Xeikon), with two types of surface treatment on the quality of the printed products. Determination of basic physical, chemical and surface characteristics (mechanical strength, optical and colorimetric characteristics of paper) as well as the evaluation of permanence according to EN ISO 9706 (∞) have shown unsuitable optical and colorimetric properties of paper. The evaluation of durability of paper and prints after accelerated artificial ageing according to the EN ISO 5630-3 standard indicates unsuitable optical and colorimetric properties, which consequently cause low optical and colorimetric stability. Colour prints with a surface protection of polymer varnish or foil protection are very unstable, causing deterioration of colour, contrasts and colour balance. The results of research work are very useful for the evaluation of durable printing paper used for various new digital printing systems and for evaluation of printing material of permanent quality.

  19. Chemical durability of glasses obtained by vitrification of industrial wastes.

    PubMed

    Pisciella, P; Crisucci, S; Karamanov, A; Pelino, M

    2001-01-01

    The vitrification of zinc-hydrometallurgy wastes, electric arc furnace dust (EAFD), drainage mud, and granite mud was shown to immobilize the hazardous components in these wastes. Batch compositions were prepared by mixing the wastes with glass-cullet and sand to force the final glass composition into the glass forming region of the SiO2-Fe2O3-(CaO, MgO) system. The vitrification was carried out in the 1400-1450 degrees C temperature range followed by quenching in water or on stainless steel mold. The United States (US) Environmental Protection Agency (EPA) toxic characterization leaching procedure (TCLP) test was used as a standard method for evaluating the leachability of the elements in the glasses and glass-ceramics samples made with different percentages of wastes. The results for EAFD glasses highlighted that the chemical stability is influenced by the glass structure formed, which, in turn, depends on the Si/O ratio in the glass. The chemical durability of jarosite glasses and glass-ceramics was evaluated by 24 h contact in NaOH, HCl and Na2CO3, at 95 degrees C. Jarosite glass-ceramics containing pyroxene (J40) are more durable than the parent glass in HCl. Jarosite glass-ceramics containing magnetite type spinels (J50) have a durability similar to the parent glass and even lower in HCl because the magnetite is soluble in HCl.

  20. Birth Dates and Death Dates: An Examination of Two Baseline Procedures and Age at Time of Death.

    ERIC Educational Resources Information Center

    Harrison, Albert A.; Kroll, Neal E. A.

    1990-01-01

    Examined birth and death dates of males listed in "Who Was Who in America." Found that, compared to men aged 71 and younger, men aged 72 and older were more likely to die on the eve of their birthdays or on their birthdays themselves. Compared to younger subjects, older subjects' death dip began at earlier point in time. (Author/NB)

  1. Highly Dispersed Alloy Catalyst for Durability

    SciTech Connect

    Vivek S. Murthi; Izzo, Elise; Bi, Wu; Guerrero, Sandra; Protsailo, Lesia

    2013-01-08

    Achieving DOE's stated 5000-hr durability goal for light-duty vehicles by 2015 will require MEAs with characteristics that are beyond the current state of the art. Significant effort was placed on developing advanced durable cathode catalysts to arrive at the best possible electrode for high performance and durability, as well as developing manufacturing processes that yield significant cost benefit. Accordingly, the overall goal of this project was to develop and construct advanced MEAs that will improve performance and durability while reducing the cost of PEMFC stacks. The project, led by UTC Power, focused on developing new catalysts/supports and integrating them with existing materials (membranes and gas diffusion layers (GDLs)) using state-of-the-art fabrication methods capable of meeting the durability requirements essential for automotive applications. Specifically, the project work aimed to lower platinum group metals (PGM) loading while increasing performance and durability. Appropriate catalysts and MEA configuration were down-selected that protects the membrane, and the layers were tailored to optimize the movements of reactants and product water through the cell to maximize performance while maintaining durability.

  2. Nap it or leave it in the elderly: A nap after practice relaxes age-related limitations in procedural memory consolidation.

    PubMed

    Korman, M; Dagan, Y; Karni, A

    2015-10-01

    Using a training protocol that effectively induces procedural memory consolidation (PMC) in young adults, we show that older adults are good learners, robustly improving their motor performance during training. However, performance declined over the day, and overnight 'offline' consolidation phase performance gains were under-expressed. A post-training nap countered these deficits. PMC processes are preserved but under-engaged in the elderly; sleep can relax some of the age-related constraints on long-term plasticity. PMID:26348880

  3. Durability of Polymeric Encapsulation Materials for Concentrating Photovoltaic Systems (Poster)

    SciTech Connect

    Miller, D. C.; Kempe, M. D.; Araki, K.; Kennedy, C. E.; Kurtz, S. R.

    2011-02-01

    Polymeric encapsulation materials are typically used in concentrating photovoltaic (CPV) modules to protect the cell from the field environment. Because it is physically located adjacent to the cell, the encapsulation is exposed to a high optical flux, often including light in the ultraviolet (UV) and infrared (IR) wavelengths. The durability of encapsulants used in CPV modules is critical to the technology, but is presently not well understood. This work seeks to identify the appropriate material types, field-induced failure mechanisms, and factors of influence (if possible) of polymeric encapsulation. These results will ultimately be weighed against those of future qualification and accelerated life test procedures.

  4. Phase VI Glove Durability Testing

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn

    2011-01-01

    The current state-of-the-art space suit gloves, the Phase VI gloves, have an operational life of 25 -- 8 hour Extravehicular Activities (EVAs) in a dust free, manufactured microgravity EVA environment. Future planetary outpost missions create the need for space suit gloves which can endure up to 90 -- 8 hour traditional EVAs or 576 -- 45 minute suit port-based EVAs in a dirty, uncontrolled planetary environment. Prior to developing improved space suit gloves for use in planetary environments, it is necessary to understand how the current state-of-the-art performs in these environments. The Phase VI glove operational life has traditionally been certified through cycle testing consisting of International Space Station (ISS)-based EVA tasks in a clean environment, and glove durability while performing planetary EVA tasks in a dirty environment has not previously been characterized. Testing was performed in the spring of 2010 by the NASA Johnson Space Center (JSC) Crew and Thermal Systems Division (CTSD) to characterize the durability of the Phase VI Glove and identify areas of the glove design which need improvement to meet the requirements of future NASA missions. Lunar simulant was used in this test to help replicate the dirty lunar environment, and generic planetary surface EVA tasks were performed during testing. A total of 50 manned, pressurized test sessions were completed in the Extravehicular Mobility Unit (EMU) using one pair of Phase VI gloves as the test article. The 50 test sessions were designed to mimic the total amount of pressurized cycling the gloves would experience over a 6 month planetary outpost mission. The gloves were inspected periodically throughout testing, to assess their condition at various stages in the test and to monitor the gloves for failures. Additionally, motion capture and force data were collected during 18 of the 50 test sessions to assess the accuracy of the cycle model predictions used in testing and to feed into the

  5. Comparison of transcatheter aortic valve and surgical bioprosthetic valve durability: a fatigue simulation study

    PubMed Central

    Martin, Caitlin; Sun, Wei

    2015-01-01

    Transcatheter aortic valve (TAV) intervention is now the standard-of-care treatment for inoperable patients and a viable alternative treatment option for high-risk patients with symptomatic aortic stenosis. While the procedure is associated with lower operative risk and shorter recovery times than traditional surgical aortic valve (SAV) replacement, TAV intervention is still not considered for lower-risk patients due in part to concerns about device durability. It is well known that bioprosthetic SAVs have limited durability, and TAVs are generally assumed to have even worse durability, yet there is little long-term data to confirm this suspicion. In this study, TAV and SAV leaflet fatigue due to cyclic loading was investigated through finite element analysis by implementing a computational soft tissue fatigue damage model to describe the behavior of the pericardial leaflets. Under identical loading conditions and with identical leaflet tissue properties, the TAV leaflets sustained higher stresses, strains, and fatigue damage compared to the SAV leaflets. The simulation results suggest that the durability of TAVs may be significantly reduced compared to SAVs to about 7.8 years. The developed computational framework may be useful in optimizing TAV design parameters to improve leaflet durability, and assessing the effects of underexpanded, elliptical, or non-uniformly expanded stent deployment on TAV durability. PMID:26294354

  6. Emotional Development across Adulthood: Differential Age-Related Emotional Reactivity and Emotion Regulation in a Negative Mood Induction Procedure

    ERIC Educational Resources Information Center

    Kliegel, Matthias; Jager, Theodor; Phillips, Louise H.

    2007-01-01

    The present study examines the hypothesis that older adults might differentially react to a negative versus neutral mood induction procedure than younger adults. The rationale for this expectation was derived from Socioemotional Selectivity Theory (SST), which postulates differential salience of emotional information and ability to regulate…

  7. Method of determining glass durability

    DOEpatents

    Jantzen, Carol Maryanne; Pickett, John Butler; Brown, Kevin George; Edwards, Thomas Barry

    1998-01-01

    A process for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, .DELTA.G.sub.p, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, .DELTA.G.sub.a, based upon the free energy associated with weak acid dissociation, .DELTA.G.sub.a.sup.WA, and accelerated matrix dissolution at high pH, .DELTA.G.sub.a.sup.SB associated with solution strong base formation, and determining a final hydration free energy, .DELTA.G.sub.f. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log.sub.10 (N C.sub.i (g/L))=a.sub.i +b.sub.i .DELTA.G.sub.f. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained.

  8. Method of determining glass durability

    DOEpatents

    Jantzen, C.M.; Pickett, J.B.; Brown, K.G.; Edwards, T.B.

    1998-12-08

    A process is described for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, {Delta}G{sub p}, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, {Delta}G{sub a}, based upon the free energy associated with weak acid dissociation, {Delta}G{sub a}{sup WA}, and accelerated matrix dissolution at high pH, {Delta}G{sub a}{sup SB} associated with solution strong base formation, and determining a final hydration free energy, {Delta}G{sub f}. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log{sub 10}(N C{sub i}(g/L))=a{sub i} + b{sub i}{Delta}G{sub f}. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained. 4 figs.

  9. Is Age a Determinant Factor in EVAR as a Predictor of Outcomes or in the Selection Procedure? Our Experience

    PubMed Central

    Machado, Rui; Teixeira, Gabriela; Oliveira, Pedro; Loureiro, Luís; Pereira, Carlos; Almeida, Rui

    2016-01-01

    Introduction Endovascular aneurysm repair (EVAR) is the therapy of choice in high risk patients with abdominal aortic aneurysm. The good results described are leading to the broadening of clinical indications to younger patients. However, reintervention rates seem higher and even with successful treatment sometimes there is growth of the aneurysm sac and rupture, meaning a failure of the therapeutic goal. This study proposes to analyse the impact of age in patients' selection and post-EVAR results. Methods The clinical records of consecutive patients undergoing endovascular aneurysm repair, between 2001 and 2013, were retrospectively reviewed. Patients were divided according to age groups (<70, 70-80 and >80 years). Gender, body mass index, aneurysm anatomic features, neck characteristics, iliac morphology, surgical indication, endograft type, anesthesic risk classification, length of stay, reinterventions and mortality were analysed and compared. Results The study included 171 patients, 161 (94.1%) men, and mean age 74.1±8.9 years. The age group under 70 had 32% of the patients. Only three characteristics were found different among age groups: 1) body mass index was higher in younger patients, with a considerable trend toward significance (P=0.06); 2) surgical indication, in the younger group, surgeon's and the patient's option were more proeminent (P<0.05); 3) erectile dysfunction was higher in elderly group (P<0.05). No other clinical and anatomical characteristics or final outcomes were found statisticaly different among age groups. Conclusion The absence of statistically differences in mortality and reinterventions among age groups suggests that age by itself is not a relevant factor in endovascular aneurysm repair. Indeed, the three characteristics different in younger (obesity, sexual function and patient's choice) favor endovascular aneurysm repair. PMID:27556312

  10. The Ross II procedure: pulmonary autograft in the mitral position.

    PubMed

    Athanasiou, Thanos; Cherian, Ashok; Ross, Donald

    2004-10-01

    The surgical management of mitral valve disease in women of childbearing age, young patients, and children with congenital mitral valve defects is made difficult by the prospect of lifelong anticoagulation. We suggest the use of a pulmonary autograft in the mitral position (Ross II procedure) as an alternative surgical technique. We present a review of the literature, historical perspectives, indications, selection criteria, and surgical technique for the Ross II procedure. Our literature search identified 14 studies that reported results from the Ross II operation. Performed in 103 patients, the overall in-hospital mortality was 7 (6.7%), with a late mortality of 10 (9%). Although further research is needed, current evidence suggests the Ross II operation is a valuable alternative in low-risk young patients where valve durability and the complication rate from other procedures is unsatisfactory and anticoagulation not ideal.

  11. 14 CFR 35.19 - Durability.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: PROPELLERS Design and Construction § 35.19 Durability. Each part of the propeller must be designed and constructed to minimize the development of any unsafe condition of the propeller...

  12. 14 CFR 35.19 - Durability.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: PROPELLERS Design and Construction § 35.19 Durability. Each part of the propeller must be designed and constructed to minimize the development of any unsafe condition of the propeller...

  13. 14 CFR 35.19 - Durability.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: PROPELLERS Design and Construction § 35.19 Durability. Each part of the propeller must be designed and constructed to minimize the development of any unsafe condition of the propeller...

  14. 14 CFR 35.19 - Durability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: PROPELLERS Design and Construction § 35.19 Durability. Each part of the propeller must be designed and constructed to minimize the development of any unsafe condition of the propeller...

  15. 14 CFR 35.19 - Durability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: PROPELLERS Design and Construction § 35.19 Durability. Each part of the propeller must be designed and constructed to minimize the development of any unsafe condition of the propeller...

  16. Structural durability of stiffened composite shells

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Rivers, James M.; Murthy, Pappu L. N.; Chamis, Christos C.

    1992-01-01

    The durability of a stiffened composite cylindrical shell panel is investigated under several loading conditions. An integrated computer code is utilized for the simulation of load induced structural degradation. Damage initiation, growth, and accumulation up to the stage of propagation to fracture are included in the computational simulation. Results indicate significant differences in the degradation paths for different loading cases. The effects of combined loading on structural durability and ultimate structural strength of a stiffened shell are assessed.

  17. Durability Assessment of Gamma Tial

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.; Pereira, J. Michael; Miyoshi, Kazuhisa; Arya, Vinod K.; Zhuang, Wyman

    2004-01-01

    Gamma TiAl was evaluated as a candidate alloy for low-pressure turbine blades in aeroengines. The durability of g-TiAl was studied by examining the effects of impact or fretting on its fatigue strength. Cast-to-size Ti-48Al-2Cr-2Nb was studied in impact testing with different size projectiles at various impact energies as the reference alloy and subsequently fatigue tested. Impacting degraded the residual fatigue life. However, under the ballistic impact conditions studied, it was concluded that the impacts expected in an aeroengine would not result in catastrophic damage, nor would the damage be severe enough to result in a fatigue failure under the anticipated design loads. In addition, other gamma alloys were investigated including another cast-to-size alloy, several cast and machined specimens, and a forged alloy. Within this Ti-48-2-2 family of alloys aluminum content was also varied. The cracking patterns as a result of impacting were documented and correlated with impact variables. The cracking type and severity was reasonably predicted using finite element models. Mean stress affects were also studied on impact-damaged fatigue samples. The fatigue strength was accurately predicted based on the flaw size using a threshold-based, fracture mechanics approach. To study the effects of wear due to potential applications in a blade-disk dovetail arrangement, the machined Ti-47-2-2 alloy was fretted against In-718 using pin-on-disk experiments. Wear mechanisms were documented and compared to those of Ti-6Al-4V. A few fatigue samples were also fretted and subsequently fatigue tested. It was found that under the conditions studied, the fretting was not severe enough to affect the fatigue strength of g-TiAl.

  18. Durability of polymer composite materials

    NASA Astrophysics Data System (ADS)

    Liu, Liu

    The purpose of this research is to examine structural durability of advanced composite materials under critical loading conditions, e.g., combined thermal and mechanical loading and shear fatigue loading. A thermal buckling model of a burnt column, either axially restrained or under an axial applied force was developed. It was predicted that for a column exposed to the high heat flux under simultaneous constant compressive load, the response of the column is the same as that of an imperfection column; the instability of the burnt column happens. Based on the simplified theoretical prediction, the post-fire compressive behavior of fiberglass reinforced vinyl-ester composite columns, which have been exposed to high heat flux for a certain time was investigated experimentally, the post-fire compressive strength, modulus and failure mode were determined. The integrity of the same column under constant compressive mechanical loading combined with heat flux exposure was examined using a specially designed mechanical loading fixture that mounted directly below a cone calorimeter. All specimens in the experiments exhibited compressive instability. The experimental results show a thermal bending moment exists and has a significant influence on the structural behavior, which verified the thermal buckling model. The trend of response between the deflection of the column and exposure time is similar to that predicted by the model. A new apparatus was developed to study the monotonic shear and cyclic-shear behavior of sandwich structures. Proof-of-concept experiments were performed using PVC foam core polymeric sandwich materials. Shear failure occurred by the extension of cracks parallel to the face-sheet/core interface, the shear modulus degraded with the growth of fatigue damage. Finite element analysis was conducted to determine stress distribution in the proposed specimen geometry used in the new technique. Details for a novel apparatus used for the fatigue testing of thin

  19. Technical note: The two step procedure (TSP) for the determination of age at death of adult human remains in forensic cases.

    PubMed

    Baccino, Eric; Sinfield, Laura; Colomb, Sophie; Baum, Thierry Pascal; Martrille, Laurent

    2014-11-01

    This paper presents the principles and results of TSP (the two step procedure), a comprehensive (combined) method of age estimation in mature human skeletal remains. The first step consists of the examination of the pubic symphysis using the Suchey-Brooks system for a "pre-choice". Then for SBS phases I, II, III, (young adults up to about 40) the age estimate is given using the chronological interval corresponding to each phase. For SBS phase is IV, V or VI (mature adults, about 40 to 60), then (second step) the dental method of Lamendin (using single rooted tooth) will be applied alone. Both methods are fast, easy to learn and to use (requiring no preparation except cleaning soft tissues from the pubic bone) and are not expensive, making TSP usable by all pathologists or anthropologists in any Forensic unit. It is also of great practical use in mass disaster and mass grave situation. After 15 years of use, a literature review and four evaluation studies we confirm that TSP is more accurate than any single method for aging adults and at least as good as more complicated combined methods. Despite its advantages TSP is, like all other aging methods, not efficient in adults over 65 years of age.

  20. Polylactic Acid-Based Polymer Blends for Durable Applications

    NASA Astrophysics Data System (ADS)

    Finniss, Adam

    , showing that no matter the treatment or formulation, PLA achieved a maximum of 30-35 percent crystallinity. Samples receiving no treatment as well as those with annealing, the addition of graphene, and in some cases annealing/graphene were subjected to both solvent and hydrolytic degradation in order to find the most stable blend or treatment. Both pellets and molded parts of varying thicknesses were investigated to evaluate the effect of diffusional resistance on long term durability. It was determined that while the addition of crystallinity or graphene platelets can provide a temporary barrier against diffusion of attacking species, PLA polymer itself is not dimensionally stable over the long lifecycle required for durable applications such as for automotive parts. In fact, PLA-only molded panels aged in distilled water at 50°C for 42 days experienced over 99% viscosity loss regardless of which treatment was applied, and nearly all mechanical strength was lost during this time. Furthermore, while the addition of graphene and the heat treatment produced diffusion barriers which could slightly enhance PLA's degradation resistance, the treatments caused the already fragile polymer to become very brittle. Solvent degradation experiments also showed that molded parts containing more than 40% PLA loading lost in excess of 75% of the original viscosity no matter what treatment was used. This showed that these materials are likely to fail well before a sufficiently long lifecycle for durable goods is achieved. Polycarbonate rich blends with less than 30% PLA as the dispersed phase showed excellent property retention after the accelerated aging tests. Formulations with up to 20% PLA content had degradation results that were nearly identical to those of 100% polycarbonate, which literature has shown to have useful lifecycles for durable applications of up to 20 years. By completely encapsulating the PLA in the polycarbonate matrix, which occurred at about 30% PLA by maximum, it

  1. Erectile Function Durability Following Permanent Prostate Brachytherapy

    SciTech Connect

    Taira, Al V.; Merrick, Gregory S.; Galbreath, Robert W.; Butler, Wayne M.; Wallner, Kent E.; Kurko, Brian S.; Anderson, Richard; Lief, Jonathan H.

    2009-11-01

    Purpose: To evaluate long-term changes in erectile function following prostate brachytherapy. Methods and Materials: This study included 226 patients with prostate cancer and preimplant erectile function assessed by the International Index of Erectile Function-6 (IIEF-6) who underwent brachytherapy in two prospective randomized trials between February 2001 and January 2003. Median follow-up was 6.4 years. Pre- and postbrachytherapy potency was defined as IIEF-6 >= 13 without pharmacologic or mechanical support. The relationship among clinical, treatment, and dosimetric parameters and erectile function was examined. Results: The 7-year actuarial rate of potency preservation was 55.6% with median postimplant IIEF of 22 in potent patients. Potent patients were statistically younger (p = 0.014), had a higher preimplant IIEF (p < 0.001), were less likely to be diabetic (p = 0.002), and were more likely to report nocturnal erections (p = 0.008). Potency preservation in men with baseline IIEF scores of 29-30, 24-28, 18-23, and 13-17 were 75.5% vs. 73.6%, 51.7% vs. 44.8%, 48.0% vs. 40.0%, and 23.5% vs. 23.5% in 2004 vs. 2008. In multivariate Cox regression analysis, preimplant IIEF, hypertension, diabetes, prostate size, and brachytherapy dose to proximal penis strongly predicted for potency preservation. Impact of proximal penile dose was most pronounced for men with IIEF of 18-23 and aged 60-69. A significant minority of men who developed postimplant impotence ultimately regained erectile function. Conclusion: Potency preservation and median IIEF scores following brachytherapy are durable. Thoughtful dose sparing of proximal penile structures and early penile rehabilitation may further improve these results.

  2. The ageing and myasthenic thymus: a morphometric study validating a standard procedure in the histological workup of thymic specimens.

    PubMed

    Ströbel, Philipp; Moritz, Regina; Leite, Maria Isabel; Willcox, Nick; Chuang, Wen-Yu; Gold, Ralf; Nix, Wilfred; Schalke, Berthold; Kiefer, Reinhard; Müller-Hermelink, Hans-Konrad; Jaretzki Iii, Alfred; Newsom-Davis, John; Marx, Alexander

    2008-09-15

    The thymus is believed to play an important role in the pathogenesis of myasthenia gravis (MG). The 80% of MG patients with anti-acetylcholine receptor autoantibodies fall into three clinical subgroups: 1) thymoma; 2) early-onset MG (<age of 40; EOMG) and 3) late-onset (LOMG; onset after 40). Thymectomy is widely used in EOMG, but its benefits have not been established in randomized controlled trials. A multicenter international trial (MGTX) currently seeks to determine whether thymectomy reduces corticosteroid requirements, and to look for correlations with thymic histology. We here describe the validated, standardized histological workup and reporting system used in this trial.

  3. Is the Cloze Procedure Appropriate to Evaluate Health Literacy in Older Individuals? Age Effects in the Test of Functional Health Literacy in Adults

    PubMed Central

    Ownby, Raymond L.; Acevedo, Amarilis; Waldrop-Valverde, Drenna; Jacobs, Robin J.

    2014-01-01

    Health literacy has received increasing attention because of its importance for older individuals' health, as studies have shown a close relation between older individuals' health literacy and their health. Research also suggests that older individuals have low levels of health literacy, but this finding is variable and may depend on which health literacy test is used. Older individuals assessed with the Test of Functional Health Literacy (TOFHLA) score lower than younger individuals, but a previous study suggested that this may result from age-related differential item functioning (DIF) on the TOFHLA. The study reported here assessed age-related DIF in a sample of community-dwelling volunteers. Twenty-two percent of items were differentially more difficult for older individuals independent of their overall ability, and when these items were eliminated from the total score, age differences were no longer found. Performance on a working memory task predicted older but not younger individuals' performance on the age-related items. At least part of older individuals' apparent deficits in health literacy when assessed by the TOFHLA may be related to DIF on its items. The TOFHLA, and any measure that employs the cloze procedure to evaluate reading comprehension, should be used cautiously in older individuals. PMID:25295191

  4. Electrochemical impedance spectroscopy for lithium-ion cells: Test equipment and procedures for aging and fast characterization in time and frequency domain

    NASA Astrophysics Data System (ADS)

    Lohmann, Nils; Weßkamp, Patrick; Haußmann, Peter; Melbert, Joachim; Musch, Thomas

    2015-01-01

    New test equipment and characterization methods for aging investigations on lithium-ion cells for automotive applications are presented in this work. Electrochemical impedance spectroscopy (EIS) is a well-established method for cell characterization and analyzing electrochemical processes. In order to integrate this method into long-term aging studies with real driving currents, new test equipment is mandatory. The presented test equipment meets the demands for high current, wide bandwidth and precise measurement. This allows the cells to be cycled and characterized without interruption for changing the test device. The characterization procedures must be of short duration and have a minimum charge-throughput for negligible influence on the aging effect. This work presents new methods in the time and the frequency domain for obtaining the impedance spectrum which allow a flexible trade-off between measurement performance, time consumption and charge-throughput. In addition to sinusoidal waveforms, rectangular, Gaussian and sin(x)/x pulses are applied for EIS. The performance of the different methods is discussed. Finally, the time domain analysis is applied with real driving currents which provides impedance spectra for state of charge estimation considering aging effects in the car.

  5. Peak procedure performance in young adult and aged rats: acquisition and adaptation to a changing temporal criterion.

    PubMed

    Lejeune, H; Ferrara, A; Soffíe, M; Bronchart, M; Wearden, J H

    1998-08-01

    Twenty-four-month-old and 4-month-old rats were trained on a peak-interval procedure, where the time of reinforcement was varied twice between 20 and 40 sec. Peak times from the old rats were consistently longer than the reinforcement time, whereas those from younger animals tracked the 20- and 40-sec durations more closely. Different measures of performance suggested that the old rats were either (1) systematically misremembering the time of reinforcement or (2) using an internal clock with a substantially greater latency to start and stop timing than the younger animals. Old rats also adjusted more slowly to the first transition from 20 to 40 sec than did the younger ones, but not to later transitions. Correlations between measures derived from within-trial patterns of responding conformed in general to detailed predictions derived from scalar expectancy theory. However, some correlation values more closely resembled those derived from a study of peak-interval performance in humans and a theoretical model developed by Cheng and Westwood (1993), than those obtained in previous work with animals, for reasons that are at present unclear.

  6. Development and validation of a Q-sort procedure to assess temperament and behavior in preschool-age children.

    PubMed

    Buckley, Maureen E; Klein, Daniel N; Durbin, C Emily; Hayden, Elizabeth P; Moerk, Kirstin C

    2002-12-01

    Few broad observational measures of preschool-age children's temperament and behavior currently exist. Studied the Child Temperament and Behavior Q-Set (CTBQ-Set) as a naturalistic observation measure to tap the major domains of temperament and behavior in preschoolers. Pairs of observers rated the behavior of a community sample of preschoolers during 2 independent home visits using q-sort methodology. The CTBQ-Set scales displayed good levels of internal consistency and convergent and discriminant content saturation. The scales displayed good interrater reliability at each observation and moderate test-retest stability between observations. The construct validity of the CTBQ-Set scales was supported by correlations with mothers' ratings of their children's behavior using the Child Behavior Checklist for 2- and 3-year-olds (CBCL/2-3) and the Children's Behavior Questionnaire. The CTBQ-Set shows promise as an observer-reated measure of preschoolers' behavior and temperament in their natural home environment.

  7. Sliding durability of candidate seal fiber materials in hydrogen from 25 to 900 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Steinetz, Bruce M.

    1992-01-01

    Sliding durability studies of candidate ceramic fibers were conducted in hydrogen to support the high temperature seal development program at NASA LeRC. Pin-on-disk tests were used to measure the friction and durability of a tow or bundle of ceramic fibers in sliding against a superalloy disk. This procedure was used previously to test candidate fibers in an air environment. The fibers based upon mullite (Al2O3-SiO2) chemistry (Nextel 550, 440, and 312) exhibited better durability in hydrogen than in air. HPZ, a complex silicon carboxynitride fiber which showed good durabilty in air, however, showed a significant loss of durability in hot hydrogen. These results are consistent with recent thermodynamic and experimental studies of ceramic compatibility with hydrogen at elevated temperatures. These research results indicate that only oxide fibers display good durability in both air and hydrogen environments. Also, simple, low cost testing in air can provide an adequate data base for initial seal material screening and selection, especially for oxide fiber candidates. The findings of this research provide critical input to the seal design team.

  8. Polylactic Acid-Based Polymer Blends for Durable Applications

    NASA Astrophysics Data System (ADS)

    Finniss, Adam

    , showing that no matter the treatment or formulation, PLA achieved a maximum of 30-35 percent crystallinity. Samples receiving no treatment as well as those with annealing, the addition of graphene, and in some cases annealing/graphene were subjected to both solvent and hydrolytic degradation in order to find the most stable blend or treatment. Both pellets and molded parts of varying thicknesses were investigated to evaluate the effect of diffusional resistance on long term durability. It was determined that while the addition of crystallinity or graphene platelets can provide a temporary barrier against diffusion of attacking species, PLA polymer itself is not dimensionally stable over the long lifecycle required for durable applications such as for automotive parts. In fact, PLA-only molded panels aged in distilled water at 50°C for 42 days experienced over 99% viscosity loss regardless of which treatment was applied, and nearly all mechanical strength was lost during this time. Furthermore, while the addition of graphene and the heat treatment produced diffusion barriers which could slightly enhance PLA's degradation resistance, the treatments caused the already fragile polymer to become very brittle. Solvent degradation experiments also showed that molded parts containing more than 40% PLA loading lost in excess of 75% of the original viscosity no matter what treatment was used. This showed that these materials are likely to fail well before a sufficiently long lifecycle for durable goods is achieved. Polycarbonate rich blends with less than 30% PLA as the dispersed phase showed excellent property retention after the accelerated aging tests. Formulations with up to 20% PLA content had degradation results that were nearly identical to those of 100% polycarbonate, which literature has shown to have useful lifecycles for durable applications of up to 20 years. By completely encapsulating the PLA in the polycarbonate matrix, which occurred at about 30% PLA by maximum, it

  9. Three-year results of a modified photodynamic therapy procedure (Ironing PDT) for age-related macular degeneration patients with large lesions

    PubMed Central

    Otsuji, Tsuyoshi; Sho, Kenichiro; Tsumura, Akiko; Koike, Naoko; Nishimura, Tetsuya; Takahashi, Kanji

    2016-01-01

    Background To evaluate the effect of photodynamic therapy (PDT) using a modified procedure on exudative age-related macular degeneration having been conventionally difficult to treat. Methods The medical records of eight consecutive patients (eight eyes) with age-related macular degeneration treated with modified PDT were reviewed retrospectively. Modified PDT was used for the lesions that could not be covered by conventional use of PDT, either because the lesion was too large or too close to the optic disc. A moving PDT laser spot at constant speed, for 83 seconds, was used to cover the entire lesion, and was named “Ironing PDT.” This retrospective study was performed with informed patient consent. It was approved by the Institutional Review Board of Kansai Medical University. Results No exudation could be found 36 months after treatment in five eyes (62.5%). There was no significant difference between the best-corrected visual acuity before PDT (0.95 logMAR) and after PDT (1.09 logMAR). The logMAR best-corrected visual acuity was improved in one eye, maintained in five eyes, and deteriorated in two eyes. Conclusion Ironing PDT decreased subfoveal fluid and preserved visual acuity in some patients with age-related macular degeneration difficult to treat with conventional therapy. PMID:27041985

  10. Evaluation of the durability of composite tidal turbine blades.

    PubMed

    Davies, Peter; Germain, Grégory; Gaurier, Benoît; Boisseau, Amélie; Perreux, Dominique

    2013-02-28

    The long-term reliability of tidal turbines is critical if these structures are to be cost effective. Optimized design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades, but there are few data available to predict material behaviour under coupled environmental and cycling loading. The present study addresses this problem, by introducing a multi-level framework for turbine blade qualification. At the material scale, static and cyclic tests have been performed, both in air and in sea water. The influence of ageing in sea water on fatigue performance is then quantified, and much lower fatigue lives are measured after ageing. At a higher level, flume tank tests have been performed on three-blade tidal turbines. Strain gauging of blades has provided data to compare with numerical models. PMID:23319705

  11. The durability of superhydrophobic films

    NASA Astrophysics Data System (ADS)

    Wang, Shing-Dar; Jiang, Ya-Syuan

    2015-12-01

    Superhydrophobic sol-gels, spin-coated on a glass substrate, were synthesized by varying the hexamethyldisilazane/tetraethoxysilane ratio (Ratio) from 1 to 2. A simple heat treatment at 200 °C for 2 h, an additional prolonged heat treatment at 200 °C for 24 h, and an additional prolonged electric field aging for 24 h with specimens connected to the positive or negative electrodes were performed. The specimens were subjected to a water impact test (WIT) for 2 h, and water contact angle (WCA) and sliding angle (SA) were measured before and after WIT. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy were employed to analyze the variations of elements and functional groups in the hydrophobic film before and after the WIT. The variations of area ratio of XPS deconvolution peaks showed that during the WIT more SiO2 groups than OSi(CH3)3 groups were washed away in the hydrophobic film. Molecular simulation provided a complete image showing the molecules constituting the surface of the hydrophobic film before and after WIT. The additional heat and electric field treatment induced Sisbnd OH network and vertical arrays of hydroxyl chains, respectively, which exerted viscous forces on the water drops but also mitigated the impact strength of the water column. Hence, before WIT, the specimen with a simple heat treatment at 200 °C for 2 h exhibited the highest WCA and lowest SA. After the WIT at a Ratio of 1.6, 1.8, and 2, SA increased in the following order: additional 24-h heat-treated specimen < electric field aging negative electrode specimen < electric field aging positive electrode specimen < simple heat-treated specimen.

  12. Durability Characterization of Advanced Polymeric Composites at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Gates, T. S.

    2001-01-01

    The next generation of reusable launch vehicles will require technology development in several key areas. Of these key areas, the development of polymeric composite cryogenic fuel tanks promises to present one of the most difficult technical challenges. It is envisioned that a polymer matrix composite (PMC) tank would be a large shell structure capable of containing cryogenic fuels and carrying a range of structural loads. The criteria that will be imposed on such a design include reduced weight, conformal geometry, and impermeability. It is this last criterion, impermeability, that will provide the focus of this paper. The essence of the impermeability criterion is that the tank remains leak free throughout its design lifetime. To address this criterion, one of the first steps is to conduct a complete durability assessment of the PMC materials. At Langley Research Center, a durability assessment of promising new polyimide-based PMCs is underway. This durability program has focused on designing a set of critical laboratory experiments that will determine fundamental material properties under combined thermal-mechanical loading at cryogenic temperatures. The test program provides measurements of lamina and laminate properties, including strength, stiffness, and fracture toughness. The performance of the PMC materials is monitored as a function of exposure conditions and aging time. Residual properties after exposure are measured at cryogenic temperatures and provide quantitative values of residual strength and stiffness. Primary degradation mechanisms and the associated damage modes are measured with both destructive and nondestructive techniques. In addition to mechanical properties, a range of physical properties, such as weight, glass transition, and crack density, are measured and correlated with the test conditions. This paper will report on the progress of this research program and present critical results and illustrative examples of current findings.

  13. 14 CFR 33.19 - Durability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; General § 33.19 Durability. (a) Engine design and construction must minimize the development of an unsafe condition of the engine between overhaul periods....

  14. Adhesive bond durability with conversion coatings

    NASA Astrophysics Data System (ADS)

    Podoba, E. A.; Kodali, S. P.; Curley, R. C.; McNamara, D.; Venables, J. D.

    The effect of processing time during conversion coating of 2024-T3 clad aluminum alloy on adhesive bond strength and durability was investigated. Iridite 14-2, both by immersion (leached and non-leached) and brush application methods, and alodine 1500 processes were studied. Bond durability and strength were determined on both primed and unprimed surfaces by performing wedge and T-peel tests, respectively. The morphology and thickness of the conversion coatings prepared by varying the processing time were studied by scanning transmission electron microscopy (STEM). The chemical composition of the surfaces was determined by electron spectroscopy for chemical analysis (ESCA). It was found that wedge test crack extensions for brush iridite 14-2 (both primed and unprimed) and primed leached iridite 14-2 surfaces were comparable to those of FPL-prepared surfaces when recommended application times were observed. Unfavorable crack extensions for primed iridite 14-2, alodine 1500 (both primed and unprimed) and unprimed leached iridite 14-2 surfaces dictate that those surface preparation methods should not be used where adhesive bond durability is desired. All crack extension behavior observed can be explained by radiations in surface roughness. Surface roughness seems to be critical in achieving durable adhesive bonds.

  15. Optical durability testing of candidate solar mirrors

    SciTech Connect

    Jorgensen, G.; Kennedy, C.; King, D.; Terwilliger, K.

    2000-03-24

    Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the Concentrated Solar Power (CSP) Program. Outdoor exposure testing (OET) at up to eight outdoor, worldwide exposure sites has been underway for several years. This includes collaboration under the auspices of the International Energy Agency (IEA) Solar Power and Chemical Energy Systems (SolarPACES) agreement. Outdoor sites are fully instrumented in terms of monitoring meteorological conditions and solar irradiance. Candidate materials are optically characterized prior to being subjected to exposure in real and simulated weathering environments. Optical durability is quantified by periodically re-measuring hemispherical and specular reflectance as a function of exposure time. By closely monitoring the site- and time-dependent environmental stress conditions experienced by the material samples, site-dependent loss of performance may be quantified. In addition, accelerated exposure testing (AET) of these materials in parallel under laboratory-controlled conditions may permit correlating the outdoor results with AET, and subsequently predicting service lifetimes. Test results to date for a large number of candidate solar reflector materials are presented in this report. Acronyms are defined. Based upon OET and AET results to date, conclusions can be drawn about the optical durability of the candidate reflector materials. The optical durability of thin glass, thick glass, and two metallized polymers can be characterized as excellent. The all-polymeric construction, several of the aluminized reflectors, and a metallized polymer can be characterized as having intermediate durability and require further improvement, testing and evaluation, or both.

  16. Durable superhydrophobic carbon soot coatings for sensor applications

    NASA Astrophysics Data System (ADS)

    Esmeryan, K. D.; Radeva, E. I.; Avramov, I. D.

    2016-01-01

    A novel approach for the fabrication of durable superhydrophobic (SH) carbon soot coatings used in quartz crystal microbalance (QCM) based gas or liquid sensors is reported. The method uses modification of the carbon soot through polymerization of hexamethyldisiloxane (HMDSO) by means of glow discharge RF plasma. The surface characterization shows a fractal-like network of carbon nanoparticles with diameter of ~50 nm. These particles form islands and cavities in the nanometer range, between which the plasma polymerized hexamethyldisiloxane (PPHMDSO) embeds and binds to the carbon chains and QCM surface. Such modified surface structure retains the hydrophobic nature of the soot and enhances its robustness upon water droplet interactions. Moreover, it significantly reduces the insertion loss and dynamic resistance of the QCM compared to the commonly used carbon soot/epoxy resin approach. Furthermore, the PPHMDSO/carbon soot coating demonstrates durability and no aging after more than 40 probing cycles in water based liquid environments. In addition, the surface layer keeps its superhydrophobicity even upon thermal annealing up to 540 °C. These experiments reveal an opportunity for the development of soot based SH QCMs with improved electrical characteristics, as required for high-resolution gas or liquid measurements.

  17. Application of EB repair for high durable MoSi PSM

    NASA Astrophysics Data System (ADS)

    Kanamitsu, Shingo; Morishita, Keiko; Hirano, Takashi

    2014-07-01

    Recently there has been a demand for high durability MoSi masks. There are some candidates for MoSi mask materials. They are preferable for both mask user and mask manufacture because they show not only high durability against exposure or cleaning process but also process compatibility in production line[1]. They are gaining momentum to practical application. However, there is a drawback for manufacturing regarding the mask repair process. Because ebeam repair employs pure chemical reaction, it faces severe etching difficulty due to higher chemical stability. Meanwhile, the tool supplier has looked into that chemical reaction in detail since the problem was unveiled. They developed a dedicated etching process for high durable materials. It's so important for the mask manufacturer to evaluate this process properly before they transfer conventional MoSi to new high durability MoSi. A comprehensive understanding of this new process should be acquired by trying several kinds of etching tests. In this paper we will report the results ranging from basic etching rate, selectivity, repair accuracy to flexibility for complicated shaped defects. This data tells us a lot about if it can be applied for practical use. The experiment was performed with e-beam repair tool "MeRiTⓇ", which was released as the latest version from ZEISS last year. An improved new etching process was applied to "A6L2" type high durable blanks provided by HOYA corporation. A wide variety of programmed defects were arranged on a line and space featured test mask. These programmed defects were repaired with the procedure developed by ZEISS. After repair, printed image was evaluated by AIMSTM system. This paper will discuss the initial results of these first steps into the uncharted territory of high durability MoSi repair.

  18. Completion of a Durable Power of Attorney for Health Care: What Does Cognition Have to Do with It?

    ERIC Educational Resources Information Center

    McGuire, Lisa C.; Rao, Jaya K.; Anderson, Lynda A.; Ford, Earl S.

    2007-01-01

    Purpose: This study examined the association between cognitive functioning and completion of a durable power of attorney for health care. Design and Methods: Participants were from the Second Longitudinal Study on Aging (LSOA II), a nationally representative sample of community-dwelling persons who were at least 70 years of age at the time of…

  19. Platinum-aluminide coating enhances durability

    SciTech Connect

    Punola, D.; Sikkenga, D.; Sutton, M.

    1995-12-01

    Severe demands on coatings for gas turbine engines that must operate at significantly higher temperatures than previously required have led to the development of an advanced two-step platinum-modified-aluminide diffusion coating. The conventional system consists of platinum electroplating followed by a traditional pack cementation aluminizing process. This coating greatly extends the durability of hot-section components in environments characterized by high-temperature oxidation and corrosion. Conventionally deposited platinum aluminides, such as Howmet`s LDC2E, demonstrated that a change in material could deliver higher levels of durability. However, the next challenge was to develop a more controllable, faster, cleaner process with improved yield and quality levels. The challenge was met by chemical vapor deposition (CVD). This method is now used to apply aluminum to the part after platinum electroplating. It replaces the traditional pack cementation or above-the-pack techniques, and bypasses all the shortcomings associated with those processes.

  20. Environmental durability of ceramics and ceramic composites

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.

    1992-01-01

    An account is given of the current understanding of the environmental durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' environmental durability. Attention is given to the environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature environmental response.

  1. Durability Testing of Commercial Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Schienle, J. L.

    1996-01-01

    Technical efforts by AlliedSignal Engines in DOE/NASA-funded project from February, 1978 through December, 1995 are reported in the fields ceramic materials for gas turbine engines and cyclic thermal durability testing. A total of 29 materials were evaluated in 40 cyclic oxidation exposure durability tests. Ceramic test bars were cyclically thermally exposed to a hot combustion environment at temperatures up to 1371 C (2500 F) for periods of up to 3500 hours, simulating conditions typically encountered by hot flowpath components in an automotive gas turbine engine. Before and after exposure, quarter-point flexure strength tests were performed on the specimens, and fractography examinations including scanning electron microscopy (SEM) were performed to determine failure origins.

  2. Verification tests of durable TPS concepts

    NASA Technical Reports Server (NTRS)

    Shideler, J. L.; Webb, G. L.; Pittman, C. M.

    1984-01-01

    Titanium multiwall, superalloy honeycomb, and Advanced Carbon-carbon (ACC) multipost Thermal Protection System (TPS) concepts are being developed to provide durable protection for surfaces of future space transportation systems. Verification tests including thermal, vibration, acoustic, water absorption, lightning strike, and aerothermal tests are described. Preliminary results indicate that the three TPS concepts are viable up to a surface temperature in excess of 2300 F.

  3. Durability Evaluation of Reversible Solid Oxide Cells

    SciTech Connect

    Xiaoyu Zhang; James E. O'Brien; Robert C. O'Brien; Gregory K. Housley

    2013-11-01

    An experimental investigation on the performance and durability of single solid oxide cells (SOCs) is under way at the Idaho National Laboratory. Reversible operation of SOCs includes electricity generation in the fuel cell mode and hydrogen generation in the electrolysis mode. Degradation is a more significant issue when operating SOCs in the electrolysis mode. In order to understand and mitigate the degradation issues in high temperature electrolysis, single SOCs with different configurations from several manufacturers have been evaluated for initial performance and long-term durability. A new test apparatus for single cell and small stack tests has been developed for this purpose. Cells were obtained from four industrial partners. Cells from Ceramatec Inc. and Materials and Systems Research Inc. (MSRI) showed improved durability in electrolysis mode compared to previous stack tests. Cells from Saint Gobain Advanced Materials Inc. (St. Gobain) and SOFCPower Inc. demonstrated stable performance in the fuel cell mode, but rapid degradation in the electrolysis mode, especially at high current density. Electrolyte-electrode delamination was found to have a significant impact on degradation in some cases. Enhanced bonding between electrolyte and electrode and modification of the electrode microstructure helped to mitigate degradation. Polarization scans and AC impedance measurements were performed during the tests to characterize cell performance and degradation.

  4. Creep Behavior and Durability of Cracked CMC

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Fox, Dennis; Smith, Craig

    2015-01-01

    To understand failure mechanisms and durability of cracked Ceramic matrix composites (CMCs), Melt Infiltration (MI) SiCSiC composites with Sylramic-iBN fibers and full Chemical vapour infiltration SiCSiC composites with Sylramic-ion bombarded BN (iBN) and Hi-Nicalon -S fibers were pre-cracked between 150 to 200 megapascal and then creep and Sustained Peak Low Cycle Fatigue (SPLCF) tested at 13150 C at stress levels from 35 to 103 megapascal for up to 200 hours under furnace and burner rig conditions. In addition creep testing was also conducted on pre-cracked full Chemical vapour infiltration SiCSiC composites at 14500 C between 35 and 103 megapascal for up to 200 hours under furnace conditions. If the specimens survived the 200 hour durability tests, then they were tensile tested at room temperature to determine their residual tensile properties. The failed specimens were examined by Scanning electron microscope (SEM) to determine the failure modes and mechanisms. The influence of crack healing matrix, fiber types, crack density, testing modes and interface oxidation on durability of cracked Ceramic matrix composites (CMCs) will be discussed.

  5. Experimental study on durability improvement of fly ash concrete with durability improving admixture.

    PubMed

    Quan, Hong-zhu; Kasami, Hideo

    2014-01-01

    In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%-20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized.

  6. Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

    PubMed Central

    Quan, Hong-zhu; Kasami, Hideo

    2014-01-01

    In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%–20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized. PMID:25013870

  7. Sequential Hybrid Procedure for Persistent Atrial Fibrillation

    PubMed Central

    Bulava, Alan; Mokracek, Ales; Hanis, Jiri; Kurfirst, Vojtech; Eisenberger, Martin; Pesl, Ladislav

    2015-01-01

    Background Catheter ablation of persistent atrial fibrillation yields an unsatisfactorily high number of failures. The hybrid approach has recently emerged as a technique that overcomes the limitations of both surgical and catheter procedures alone. Methods and Results We investigated the sequential (staged) hybrid method, which consists of a surgical thoracoscopic radiofrequency ablation procedure followed by radiofrequency catheter ablation 6 to 8 weeks later using the CARTO 3 mapping system. Fifty consecutive patients (mean age 62±7 years, 32 males) with long‐standing persistent atrial fibrillation (41±34 months) and a dilated left atrium (>45 mm) were included and prospectively followed in an unblinded registry. During the electrophysiological part of the study, all 4 pulmonary veins were found to be isolated in 36 (72%) patients and a complete box‐lesion was confirmed in 14 (28%) patients. All gaps were successfully re‐ablated. Twelve months after the completed hybrid ablation, 47 patients (94%) were in normal sinus rhythm (4 patients with paroxysmal atrial fibrillation required propafenone and 1 patient underwent a redo catheter procedure). The majority of arrhythmias recurred during the first 3 months. Beyond 12 months, there were no arrhythmia recurrences detected. The surgical part of the procedure was complicated by 7 (13.7%) major complications, while no serious adverse events were recorded during the radiofrequency catheter part of the procedure. Conclusions The staged hybrid epicardial–endocardial treatment of long‐standing persistent atrial fibrillation seems to be extremely effective in maintenance of normal sinus rhythm compared to radiofrequency catheter or surgical ablation alone. Epicardial ablation alone cannot guarantee durable transmural lesions. Clinical Trial Registration URL: www.ablace.cz Unique identifier: cz‐060520121617 PMID:25809548

  8. Durability of Cement Composites Reinforced with Sisal Fiber

    NASA Astrophysics Data System (ADS)

    Wei, Jianqiang

    This dissertation focuses mainly on investigating the aging mechanisms and degradation kinetics of sisal fiber, as well as the approaches to mitigate its degradation in the matrix of cement composites. In contrast to previous works reported in the literature, a novel approach is proposed in this study to directly determine the fiber's degradation rate by separately studying the composition changes, mechanical and physical properties of the embedded sisal fibers. Cement hydration is presented to be a crucial factor in understanding fiber degradation behavior. The degradation mechanisms of natural fiber consist of mineralization of cell walls, alkali hydrolysis of lignin and hemicellulose, as well as the cellulose decomposition which includes stripping of cellulose microfibrils and alkaline hydrolysis of amorphous regions in cellulose chains. Two mineralization mechanisms, CH-mineralization and self-mineralization, are proposed. The degradation kinetics of sisal fiber in the cement matrix are also analyzed and a model to predict the degradation rate of cellulose for natural fiber embedded in cement is outlined. The results indicate that the time needed to completely degrade the cellulose in the matrix with cement replacement by 30wt.% metakaolin is 13 times longer than that in pure cement. A novel and scientific method is presented to determine accelerated aging conditions, and to evaluating sisal fiber's degradation rate and durability of natural fiber-reinforced cement composites. Among the static aggressive environments, the most effective approach for accelerating the degradation of natural fiber in cement composites is to soak the samples or change the humidity at 70 °C and higher temperature. However, the dynamic wetting and drying cycling treatment has a more accelerating effect on the alkali hydrolysis of fiber's amorphous components evidenced by the highest crystallinity indices, minimum content of holocellulose, and lowest tensile strength. Based on the

  9. Durability Testing of Fluidized Bed Steam Reforming Products

    SciTech Connect

    JANTZEN, CAROL M.; PAREIZS, JOHN M.; LORIER, TROY H.; MARRA, JAMES C.

    2005-07-01

    Fluidized Bed Steam Reforming (FBSR) is being considered as a potential technology for the immobilization of a wide variety of radioactive wastes but especially aqueous high sodium wastes at the Hanford site, at the Idaho National Laboratory (INL), and at the Savannah River Site (SRS). The FBSR technology converts organic compounds to CO{sub 2} and H{sub 2}O, converts nitrate/nitrite species to N{sub 2}, and produces a solid residue through reactions with superheated steam, the fluidizing media. If clay is added during processing a ''mineralized'' granular waste form can be produced. The mineral components of the waste form are primarily Na-Al-Si (NAS) feldspathoid minerals with cage-like and ring structures and iron bearing spinel minerals. The cage and ring structured minerals atomically bond radionuclides like Tc{sup 99} and Cs{sup 137} and anions such as SO{sub 4}, I, F, and Cl. The spinel minerals appear to stabilize Resource Conservation and Recovery Act (RCRA) hazardous species such as Cr and Ni. Durability testing of the FBSR products was performed using ASTM C1285 (Product Consistency Test) and the Environmental Protection Agency (EPA) Toxic Characteristic Leaching Procedure (TCLP). The FBSR mineral products (bed and fines) evaluated in this study were found to be two orders of magnitude more durable than the Hanford Low Activity Waste (LAW) glass requirement of 2 g/m{sup 2} release of Na{sup +}. The PCT responses for the FBSR samples tested were consistent with results from previous FBSR Hanford LAW product testing. Differences in the response can be explained by the minerals formed and their effects on PCT leachate chemistry.

  10. Durable fear memories require PSD-95

    PubMed Central

    Fitzgerald, Paul J.; Pinard, Courtney R.; Camp, Marguerite C.; Feyder, Michael; Sah, Anupam; Bergstrom, Hadley; Graybeal, Carolyn; Liu, Yan; Schlüter, Oliver; Grant, Seth G.N.; Singewald, Nicolas; Xu, Weifeng; Holmes, Andrew

    2014-01-01

    Traumatic fear memories are highly durable but also dynamic, undergoing repeated reactivation and rehearsal over time. While overly persistent fear memories underlie anxiety disorders such as posttraumatic stress disorder, the key neural and molecular mechanisms underlying fear memory durability remain unclear. Post-synaptic density 95 (PSD-95) is a synaptic protein regulating glutamate receptor anchoring, synaptic stability and certain types of memory. Employing a loss-of-function mutant mouse lacking the guanylate kinase domain of PSD-95 (PSD-95GK), we analyzed the contribution of PSD-95 to fear memory formation and retrieval, and sought to identify the neural basis of PSD-95-mediated memory maintenance using ex vivo immediate-early gene mapping, in vivo neuronal recordings and viral-mediated knockdown approaches. We show that PSD-95 is dispensable for the formation and expression of recent fear memories, but essential for the formation of precise and flexible fear memories and for the maintenance of memories at remote time points. The failure of PSD-95GK mice to retrieve remote cued fear memories was associated with hypoactivation of the infralimbic cortex (IL) (not anterior cingulate (ACC) or prelimbic cortex), reduced IL single-unit firing and bursting, and attenuated IL gamma and theta oscillations. Adeno-associated PSD-95 virus-mediated knockdown in the IL, not ACC, was sufficient to impair recent fear extinction and remote fear memory, and remodel IL dendritic spines. Collectively, these data identify PSD-95 in the IL as a critical mechanism supporting the durability of fear memories over time. These preclinical findings have implications for developing novel approaches to treating trauma-based anxiety disorders that target the weakening of overly persistent fear memories. PMID:25510511

  11. Durable fear memories require PSD-95.

    PubMed

    Fitzgerald, P J; Pinard, C R; Camp, M C; Feyder, M; Sah, A; Bergstrom, H C; Graybeal, C; Liu, Y; Schlüter, O M; Grant, S G; Singewald, N; Xu, W; Holmes, A

    2015-07-01

    Traumatic fear memories are highly durable but also dynamic, undergoing repeated reactivation and rehearsal over time. Although overly persistent fear memories underlie anxiety disorders, such as posttraumatic stress disorder, the key neural and molecular mechanisms underlying fear memory durability remain unclear. Postsynaptic density 95 (PSD-95) is a synaptic protein regulating glutamate receptor anchoring, synaptic stability and certain types of memory. Using a loss-of-function mutant mouse lacking the guanylate kinase domain of PSD-95 (PSD-95(GK)), we analyzed the contribution of PSD-95 to fear memory formation and retrieval, and sought to identify the neural basis of PSD-95-mediated memory maintenance using ex vivo immediate-early gene mapping, in vivo neuronal recordings and viral-mediated knockdown (KD) approaches. We show that PSD-95 is dispensable for the formation and expression of recent fear memories, but essential for the formation of precise and flexible fear memories and for the maintenance of memories at remote time points. The failure of PSD-95(GK) mice to retrieve remote cued fear memory was associated with hypoactivation of the infralimbic (IL) cortex (but not the anterior cingulate cortex (ACC) or prelimbic cortex), reduced IL single-unit firing and bursting, and attenuated IL gamma and theta oscillations. Adeno-associated virus-mediated PSD-95 KD in the IL, but not the ACC, was sufficient to impair recent fear extinction and remote fear memory, and remodel IL dendritic spines. Collectively, these data identify PSD-95 in the IL as a critical mechanism supporting the durability of fear memories over time. These preclinical findings have implications for developing novel approaches to treating trauma-based anxiety disorders that target the weakening of overly persistent fear memories. PMID:25510511

  12. Durable fear memories require PSD-95.

    PubMed

    Fitzgerald, P J; Pinard, C R; Camp, M C; Feyder, M; Sah, A; Bergstrom, H C; Graybeal, C; Liu, Y; Schlüter, O M; Grant, S G; Singewald, N; Xu, W; Holmes, A

    2015-07-01

    Traumatic fear memories are highly durable but also dynamic, undergoing repeated reactivation and rehearsal over time. Although overly persistent fear memories underlie anxiety disorders, such as posttraumatic stress disorder, the key neural and molecular mechanisms underlying fear memory durability remain unclear. Postsynaptic density 95 (PSD-95) is a synaptic protein regulating glutamate receptor anchoring, synaptic stability and certain types of memory. Using a loss-of-function mutant mouse lacking the guanylate kinase domain of PSD-95 (PSD-95(GK)), we analyzed the contribution of PSD-95 to fear memory formation and retrieval, and sought to identify the neural basis of PSD-95-mediated memory maintenance using ex vivo immediate-early gene mapping, in vivo neuronal recordings and viral-mediated knockdown (KD) approaches. We show that PSD-95 is dispensable for the formation and expression of recent fear memories, but essential for the formation of precise and flexible fear memories and for the maintenance of memories at remote time points. The failure of PSD-95(GK) mice to retrieve remote cued fear memory was associated with hypoactivation of the infralimbic (IL) cortex (but not the anterior cingulate cortex (ACC) or prelimbic cortex), reduced IL single-unit firing and bursting, and attenuated IL gamma and theta oscillations. Adeno-associated virus-mediated PSD-95 KD in the IL, but not the ACC, was sufficient to impair recent fear extinction and remote fear memory, and remodel IL dendritic spines. Collectively, these data identify PSD-95 in the IL as a critical mechanism supporting the durability of fear memories over time. These preclinical findings have implications for developing novel approaches to treating trauma-based anxiety disorders that target the weakening of overly persistent fear memories.

  13. Chemistry of Durable and Regenerable Biocidal Textiles

    NASA Astrophysics Data System (ADS)

    Sun, Gang; Worley, S. Dave

    2005-01-01

    Unlike the widely used slow-releasing biocidal mechanism now employed in biocidal textiles, a novel regenerable process, based on a regeneration principle and halamine chemistry, has been developed in antimicrobial finishing of textiles. Halamine-modified textile materials demonstrate durable and regenerable antimicrobial functions and execute rapid inactivation of a broad spectrum of microorganisms by contact without yielding drug resistance. The unique properties of the products render them useful materials for medical-use and hygienic textiles. The chemistry of the biocidal materials is be discussed. See Featured Molecules .

  14. Durable, Low-Surface-Energy Treatments

    NASA Technical Reports Server (NTRS)

    Willis, Paul B.; Mcelroy, Paul M.; Hickey, Gregory S.

    1992-01-01

    Chemical treatment for creation of durable, low-surface-energy coatings for glass, ceramics and other protonated surfaces easily applied, and creates very thin semipermanent film with extremely low surface tension. Exhibits excellent stability; surfaces retreated if coating becomes damaged or eroded. Uses include water-repellent surfaces, oil-repellent surfaces, antimigration barriers, corrosion barriers, mold-release agents, and self-cleaning surfaces. Film resists wetting by water, alcohols, hydrocarbon solvents, and silicone oil. Has moderate resistance to abrasion, such as rubbing with cloths, and compression molding to polymers and composite materials.

  15. Environmental durability of electroplated black chromium

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1981-01-01

    A study was undertaken to determine the durability of nickel-black chromium plated aluminum in an outdoor rural industrial, and seacoast environment. Test panels were exposed to these environments for 60, 36, and 13 months, respectively. The results of this study showed that no significant optical degradation occurred from exposure to either of these environments, although a considerable amount of corrosion occurred on the panels exposed to the seacoast environment. The rural and industrial atmosphere produced only a slight amount of corrosion on test panels.

  16. Durability of composites in automotive structural applications

    SciTech Connect

    Corum, J.M.; Battiste, R.L.; McCoy, H.E.; Ruggles, M.B.; Simpson, W.A.; Weitsman, Y.J.

    1996-10-01

    The overall goal of the project is to develop experimentally-based, durability-driven design guidelines for automotive composite structures and to demonstrate their applicability to lightweight, manufacturable structures under representative field loading histories and environments. Key technical issues are the potentially degrading effects that (1) both cyclic and long-term sustained loadings, (2) various automotive environments, and (3) low-energy impacts can have on the dimensional stability, strength, and stiffness of automotive composite structures. The purpose of this paper is to present the findings and observations developed to date and to outline future directions.

  17. Advanced Face Gear Surface Durability Evaluations

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Heath, Gregory F.

    2016-01-01

    The surface durability life of helical face gears and isotropic super-finished (ISF) face gears was investigated. Experimental fatigue tests were performed at the NASA Glenn Research Center. Endurance tests were performed on 10 sets of helical face gears in mesh with tapered involute helical pinions, and 10 sets of ISF-enhanced straight face gears in mesh with tapered involute spur pinions. The results were compared to previous tests on straight face gears. The life of the ISF configuration was slightly less than that of previous tests on straight face gears. The life of the ISF configuration was slightly greater than that of the helical configuration.

  18. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  19. Combined hydrophobicity and mechanical durability through surface nanoengineering

    SciTech Connect

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen; Furrer, David U.; Burlatsky, Sergei F.; Filburn, Thomas P.

    2015-04-08

    This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability.

  20. Combined Hydrophobicity and Mechanical Durability through Surface Nanoengineering

    PubMed Central

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen; Furrer, David U.; Burlatsky, Sergei F.; Filburn, Thomas P.

    2015-01-01

    This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability. PMID:25851026

  1. Durable Nanocomposites for Superhydrophobicity and Superoleophobicity

    NASA Astrophysics Data System (ADS)

    Steele, Adam

    Anti-wetting surfaces and materials have the potential for dramatic performance improvements such as drag reduction on marine vehicles and fluid power systems as well as anti-fouling on aircraft and wind turbines. Although a wide variety of synthetic superhydrophobic surfaces have been developed and investigated, several critical obstacles remain before industrial application can be realized, including: (1) large surface area application, (2) multi-liquid anti-wetting, (3) environmentally friendly compositions, (4) mechanical durability and adhesion, and (5) long-term performance. In this dissertation, nanocomposite coatings have been investigated to generate high performance anti-wetting surfaces that address these obstacles which may enable application on wind turbine blades. Solution processable materials were used which self-assemble to create anti-wetting nanocomposite surfaces upon spray coating and curing. As a result, the first superoleophobic nanocomposite, the first environmentally friendly superhydrophobic compositions, and the first highly durable superhydrophobic nanocomposite coatings were created. Furthermore, the mechanisms leading to this improved performance were studied.

  2. CHP Fuel Cell Durability Demonstration - Final Report

    SciTech Connect

    Petrecky, James; Ashley, Christopher J

    2014-07-21

    Plug Power has managed a demonstration project that has tested multiple units of its high-temperature, PEM fuel cell system in micro-combined heat and power (μ-CHP) applications in California. The specific objective of the demonstration project was to substantiate the durability of GenSys Blue, and, thereby, verify its technology and commercial readiness for the marketplace. In the demonstration project, Plug Power, in partnership with the National Fuel Cell Research Center (NFCRC) at the University of California, Irvine (UCI), and Sempra, will execute two major tasks: • Task 1: Internal durability/reliability fleet testing. Six GenSys Blue units will be built and will undergo an internal test regimen to estimate failure rates. This task was modified to include 3 GenSys Blue units installed in a lab at UCI. • Task 2: External customer testing. Combined heat and power units will be installed and tested in real-world residential and/or light commercial end user locations in California.

  3. Evaluation of models of waste glass durability

    SciTech Connect

    Ellison, A.

    1995-08-01

    The main variable under the control of the waste glass producer is the composition of the glass; thus a need exists to establish functional relationships between the composition of a waste glass and measures of processability, product consistency, and durability. Many years of research show that the structure and properties of a glass depend on its composition, so it seems reasonable to assume that there also is relationship between the composition of a waste glass and its resistance to attack by an aqueous solution. Several models have been developed to describe this dependence, and an evaluation their predictive capabilities is the subject of this paper. The objective is to determine whether any of these models describe the ``correct`` functional relationship between composition and corrosion rate. A more thorough treatment of the relationships between glass composition and durability has been presented elsewhere, and the reader is encouraged to consult it for a more detailed discussion. The models examined in this study are the free energy of hydration model, developed at the Savannah River Laboratory, the structural bond strength model, developed at the Vitreous State Laboratory at the Catholic University of America, and the Composition Variation Study, developed at Pacific Northwest Laboratory.

  4. Mechanically durable superhydrophobic surfaces prepared by abrading

    NASA Astrophysics Data System (ADS)

    Wang, Fajun; Yu, Shan; Ou, Junfei; Xue, Mingshan; Li, Wen

    2013-09-01

    Superhydrophobic surfaces with both excellent mechanical durability and easy reparability based on polytetrafluoroethylene/room temperature vulcanized silicone rubber (PTFE/RTVSR) composites were prepared by a simple abrading method. The surface energy of RTVSR matrix decreased with the increasing volume fraction of PTFE particles, and the surface rough microstructures of the composites were created by abrading. A water droplet on the surface exhibited a contact angle of about 165° ± 3.4° and a sliding angle of about 7.3° ± 1.9°. Such superhydrophobic surfaces showed strong mechanical durability against sandpaper because the surfaces were prepared in the way of mechanical abrasion, and the fresh exposed surfaces were still superhydrophobic. In addition, the micro-structures on the elastic surface of the composite will be compressed by elastic deformation to avoid being broken during the friction cycles when cotton fabric was used as an abrasion surface. The deformation will rebound to renew the original surface structures when the load is withdrawn. Therefore, the elastic PTFE/RTVSR composites are of advantage to construct superhydrophobic surfaces with better abrasion resistance. More importantly, such superhydrophobicity can be repaired by a simple abrading regeneration process within a few minutes when the surface is damaged or polluted by organic contaminant.

  5. Durability of ceramic catalytic converters for motorcycles

    SciTech Connect

    Reddy, K.P.; Scott, P.L.; Hwang, H.S.; Mooney, J.J.

    1995-12-31

    Motorcycle exhaust emission standards throughout the world are becoming more stringent. Emission control systems utilizing the catalytic converter are already in production in Taiwan for 2-stroke engine motorcycles. Catalysts designed for 2-stroke engines encounter a more severe exhaust environment than do those designed for 4-stroke engines. The two aspects of increased severity are the higher temperatures and higher stresses due to engine vibrations. Precious metal catalysts have been designed to operate in the thermal environment of 2-stroke engines and such catalysts have been successfully applied to both metal and ceramic substrates. However, until now, only the metal substrate catalysts have been utilized in motorcycle application. Ceramic based catalysts have not been considered because the mounting material that holds the catalyst substrate in place did not have enough durability to withstand the thermal/vibrational forces encountered in 2-stroke engine exhaust. Ceramic substrates have many advantages such as superior high temperature strength, which is especially important for the 2-stroke engine application, flexibility in cell shape and density, and lower cost. To realize these benefits, efforts were made in this study to develop better mounting systems. The results of this effort indicate that the durability requirements of 2-stroke engine can be met with the ceramic catalyst substrates if the improved mounting designs reported in the present study are employed.

  6. Durability Assessment of TiAl Alloys

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.

    2008-01-01

    The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

  7. Laundering durable antibacterial cotton fabrics grafted with pomegranate-shaped polymer wrapped in silver nanoparticle aggregations

    NASA Astrophysics Data System (ADS)

    Liu, Hanzhou; Lv, Ming; Deng, Bo; Li, Jingye; Yu, Ming; Huang, Qing; Fan, Chunhai

    2014-08-01

    To improve the laundering durability of the silver functionalized antibacterial cotton fabrics, a radiation-induced coincident reduction and graft polymerization is reported herein where a pomegranate-shaped silver nanoparticle aggregations up to 500 nm can be formed due to the coordination forces between amino group and silver and the wrapping procedure originated from the coincident growth of the silver nanoparticles and polymer graft chains. This pomegranate-shaped silver NPAs functionalized cotton fabric exhibits outstanding antibacterial activities and also excellent laundering durability, where it can inactivate higher than 90% of both E. coli and S. aureus even after 50 accelerated laundering cycles, which is equivalent to 250 commercial or domestic laundering cycles.

  8. Laundering durable antibacterial cotton fabrics grafted with pomegranate-shaped polymer wrapped in silver nanoparticle aggregations.

    PubMed

    Liu, Hanzhou; Lv, Ming; Deng, Bo; Li, Jingye; Yu, Ming; Huang, Qing; Fan, Chunhai

    2014-08-01

    To improve the laundering durability of the silver functionalized antibacterial cotton fabrics, a radiation-induced coincident reduction and graft polymerization is reported herein where a pomegranate-shaped silver nanoparticle aggregations up to 500 nm can be formed due to the coordination forces between amino group and silver and the wrapping procedure originated from the coincident growth of the silver nanoparticles and polymer graft chains. This pomegranate-shaped silver NPAs functionalized cotton fabric exhibits outstanding antibacterial activities and also excellent laundering durability, where it can inactivate higher than 90% of both E. coli and S. aureus even after 50 accelerated laundering cycles, which is equivalent to 250 commercial or domestic laundering cycles.

  9. Laundering durable antibacterial cotton fabrics grafted with pomegranate-shaped polymer wrapped in silver nanoparticle aggregations

    PubMed Central

    Liu, Hanzhou; Lv, Ming; Deng, Bo; Li, Jingye; Yu, Ming; Huang, Qing; Fan, Chunhai

    2014-01-01

    To improve the laundering durability of the silver functionalized antibacterial cotton fabrics, a radiation-induced coincident reduction and graft polymerization is reported herein where a pomegranate-shaped silver nanoparticle aggregations up to 500 nm can be formed due to the coordination forces between amino group and silver and the wrapping procedure originated from the coincident growth of the silver nanoparticles and polymer graft chains. This pomegranate-shaped silver NPAs functionalized cotton fabric exhibits outstanding antibacterial activities and also excellent laundering durability, where it can inactivate higher than 90% of both E. coli and S. aureus even after 50 accelerated laundering cycles, which is equivalent to 250 commercial or domestic laundering cycles. PMID:25082297

  10. Durability of ITO-MgF2 Films for Space-Inflatable Polymer Structures

    NASA Technical Reports Server (NTRS)

    Kerslake, Thomas W.; Waters, Deborah L.; Schieman, David A.; Hambourger, Paul D.

    2003-01-01

    This paper presents results from ITO-MgF2 film durability evaluations that included tape peel, fold, thermal cycle, and AO exposure testing. Polymer coupon preparation is described as well as ITO-MgF2 film deposition equipment, procedures and film characterization. Durability testing methods are also described. The pre- and post-test condition of the films is assessed visually, microscopically, and electrically. Results show that at 500 ITO - 9 vol% MgF2 film is suitable to protect polymer surfaces, such as those used in space-inflatable structures of the PowerSphere microsatellite concept, during a 1-year Earth orbiting mission. Future plans for ground-based and orbital testing of this film are also discussed.

  11. Study on durability for thermal cycle of planar SOFC

    SciTech Connect

    Ando, Motoo; Nakata, Kei-ichi; Wakayama, Sin-ichi

    1996-12-31

    TONEN CORPORATION has developed planar type SOFC since 1986. We demonstrated the output of 1.3 kW in 1991 and 5.1 kW in 1995. Simultaneously we have studied how to raise electric efficiency and reliability utilizing hydrogen and propane as fuel. Durability for thermal cycle is one of the most important problems of planar SOFC to make it more practical. The planar type SOFC is made up of separator, zirconia electrolyte and glass sealant. The thermal expansion of these components are expected to be the same value, however, they still possess small differences. In this situation, a thermal cycle causes a thermal stress due to the difference of the cell components and is often followed by a rupture in cell components, therefore, the analysis of the thermal stress should give us much useful information. The thermal cycle process consists of a heating up and cooling down procedure. Zirconia electrolyte is not bonded to the separator under the condition of the initial heating up procedure, and glass sealant becomes soft or melts and glass seals spaces between the zirconia and separator. The glass sealant becomes harder with the cooling down procedure. Moreover, zirconia is tightly bonded with separator below a temperature which is defined as a constraint temperature and thermal stress also occurs. This indicates that the heating up process relaxes the thermal stress and the cooling down increases it. In this paper, we simulated dependence of the stress on the sealing configuration, thermal expansion of sealant and constraint temperature of sealant glass. Furthermore, we presented SOFC electrical properties after a thermal cycle.

  12. Durable Airtightness in Single-Family Dwellings - Field Measurementsand Analysis

    SciTech Connect

    Chan, Wanyu R.; Walker, Iain S.; Sherman, Max H.

    2015-06-01

    Here, durability of the building envelope is important to new homes that are increasingly built with improved levels of airtightness. It is also important to weatherized homes such that energy savings from retrofit measures, such as air sealing, are persistent. This paper presents a comparison of air leakage measurements collected in November 2013 through March 2014, with two sets of prior data collected between 2001-2003 from 17 new homes located near Atlanta, GA, and 17 homes near Boise, ID that were weatherized in 2007- 2008. The purpose of the comparison is to determine if there are changes to the airtightness of building envelopes over time. The air leakage increased in all but one of the new homes, with a mean increase of about 25%. The weatherized homes also showed an increase in the mean air leakage (12%). A regression analysis was performed to describe the relationship between prior and current measurements in terms of normalized leakage (NL). The best estimate of the ageing factor predicts a 15% increase in NL over ten years. Further analysis using ResDB data (LBNL’s Residential Diagnostic Database) showed the expected changes in air leakage if ageing were modelled. These results imply the need to examine the causes of increased leakage and methods to avoid them. This increase in leakage with time should be accounted for in long-term population-wide energy savings estimates, such as those used in ratings or energy savings programs.

  13. Durable Airtightness in Single-Family Dwellings - Field Measurementsand Analysis

    DOE PAGES

    Chan, Wanyu R.; Walker, Iain S.; Sherman, Max H.

    2015-06-01

    Here, durability of the building envelope is important to new homes that are increasingly built with improved levels of airtightness. It is also important to weatherized homes such that energy savings from retrofit measures, such as air sealing, are persistent. This paper presents a comparison of air leakage measurements collected in November 2013 through March 2014, with two sets of prior data collected between 2001-2003 from 17 new homes located near Atlanta, GA, and 17 homes near Boise, ID that were weatherized in 2007- 2008. The purpose of the comparison is to determine if there are changes to the airtightnessmore » of building envelopes over time. The air leakage increased in all but one of the new homes, with a mean increase of about 25%. The weatherized homes also showed an increase in the mean air leakage (12%). A regression analysis was performed to describe the relationship between prior and current measurements in terms of normalized leakage (NL). The best estimate of the ageing factor predicts a 15% increase in NL over ten years. Further analysis using ResDB data (LBNL’s Residential Diagnostic Database) showed the expected changes in air leakage if ageing were modelled. These results imply the need to examine the causes of increased leakage and methods to avoid them. This increase in leakage with time should be accounted for in long-term population-wide energy savings estimates, such as those used in ratings or energy savings programs.« less

  14. Versatile, Reusable, and Inexpensive Ultrasound Phantom Procedural Trainers.

    PubMed

    Morrow, Dustin S; Cupp, Julia A; Broder, Joshua S

    2016-04-01

    We have constructed simple and inexpensive models for ultrasound-guided procedural training using synthetic ballistic gelatin. These models are durable, leak resistant, and able to be shaped to fit a variety of simulation scenarios to teach procedures. They provide realistic tactile and sonographic training for our learners in a safe, idealized setting. PMID:26969595

  15. 40 CFR 94.219 - Durability data engine selection.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Durability data engine selection. 94.219 Section 94.219 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... this section. (c) Durability data engines shall be built from subsystems and components that...

  16. Atomic Oxygen Durability of Aluminized Polymers

    NASA Technical Reports Server (NTRS)

    Yang, Judith C.

    2003-01-01

    The atomic oxygen durability of aluminized polymers will be investigated. Such aluminized polymers are commonly used in space and specifically on the International Space Station. Recent data from in-space results indicates that vapor deposited aluminum coatings are highly defected with many small pin windows. However, electron microscopy to validate the size and aerial density of such defects remains to be demonstrated. The research project is planned to compare electron microscopy analysis of pristine and atomic oxygen exposed aluminized polyimide Kapton with the results of ground laboratory atomic oxygen erosion data, in-space results and computational Monte Carlo modeling to develop a self consistent understanding of the atomic oxygen degradation processes and effects.

  17. Outdoor durability of radiation-cured coatings

    SciTech Connect

    Holman, R.; Kennedy, R.

    1997-12-31

    Radiation cured coatings are used almost exclusively on products which have little or no exposure to moisture or the weather; inks, furniture varnishes, floor varnishes and coatings for electronic components. However there is considerable interest in being able to use this technology in exterior environments as a substitute for solvent-borne coatings. A 3-year study examining the possible reasons for the poor durability of radiation curable coatings showed that the resistance of the monomers and oligomers to hydrogen abstraction was crucially important, and the water permeability of the cured coating influenced the long-term adhesion performance. The project concluded that with the appropriate combination of curing technology and monomer/oligomer selection, the prospects of UV curable coatings for outdoor exposure are very encouraging.

  18. Lightweight, durable lead-acid batteries

    SciTech Connect

    Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O; Dudney, Nancy J; Contescu, Cristian I; Baker, Frederick S; Armstrong, Beth L

    2013-05-21

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  19. Lightweight, durable lead-acid batteries

    DOEpatents

    Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O.; Dudney, Nancy J.; Contescu, Cristian I.; Baker, Frederick S.; Armstrong, Beth L.

    2011-09-13

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  20. DROP: Durable Reconnaissance and Observation Platform

    NASA Technical Reports Server (NTRS)

    Parness, Aaron; McKenzie, Clifford F.

    2012-01-01

    Robots have been a valuable tool for providing a remote presence in areas that are either inaccessible or too dangerous for humans. Having a robot with a high degree of adaptability becomes crucial during such events. The adaptability that comes from high mobility and high durability greatly increases the potential uses of a robot in these situations, and therefore greatly increases its usefulness to humans. DROP is a lightweight robot that addresses these challenges with the capability to survive large impacts, carry a usable payload, and traverse a variety of surfaces, including climbing vertical surfaces like wood, stone, and concrete. The platform is crash-proof, allowing it to be deployed in ways including being dropped from an unmanned aerial vehicle or thrown from a large MSL-class (Mars Science Laboratory) rover.

  1. Durability of Silicate Glasses: An Historical Approach

    SciTech Connect

    Farges, Francois; Etcheverry, Marie-Pierre; Haddi, Amine; Trocellier, Patrick; Curti, Enzo; Brown, Gordon E., Jr.; /SLAC, SSRL

    2007-01-02

    We present a short review of current theories of glass weathering, including glass dissolution, and hydrolysis of nuclear waste glasses, and leaching of historical glasses from an XAFS perspective. The results of various laboratory leaching experiments at different timescales (30 days to 12 years) are compared with results for historical glasses that were weathered by atmospheric gases and soil waters over 500 to 3000 years. Good agreement is found between laboratory experiments and slowly leached historical glasses, with a strong enrichment of metals at the water/gel interface. Depending on the nature of the transition elements originally dissolved in the melt, increasing elemental distributions are expected to increase with time for a given glass durability context.

  2. Thermal fatigue durability for advanced propulsion materials

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.

    1989-01-01

    A review is presented of thermal and thermomechanical fatigue (TMF) crack initiation life prediction and cyclic constitutive modeling efforts sponsored recently by the NASA Lewis Research Center in support of advanced aeronautical propulsion research. A brief description is provided of the more significant material durability models that were created to describe TMF fatigue resistance of both isotropic and anisotropic superalloys, with and without oxidation resistant coatings. The two most significant crack initiation models are the cyclic damage accumulation model and the total strain version of strainrange partitioning. Unified viscoplastic cyclic constitutive models are also described. A troika of industry, university, and government research organizations contributed to the generation of these analytic models. Based upon current capabilities and established requirements, an attempt is made to project which TMF research activities most likely will impact future generation propulsion systems.

  3. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Milbourne, M.

    2005-01-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. The objective of this task is to quantify lifetimes through measurement of the optical and mechanical stability of candidate polymeric glazing and absorber materials. Polycarbonate sheet glazings, as proposed by two industry partners, have been tested for resistance to UV radiation with three complementary methods. Incorporation of a specific 2-mil thick UV-absorbing screening layer results in glazing lifetimes of at least 15 years; improved screens promise even longer lifetimes. Proposed absorber materials were tested for creep and embrittlement under high temperature, and appear adequate for planned ICS absorbers.

  4. Durability of incinerator ash waste encapsulated in modified sulfur cement

    SciTech Connect

    Kalb, P.D.; Heiser, J.H. III; Pietrzak, R.; Colombo, P.

    1991-01-01

    Waste form stability under anticipated disposal conditions is an important consideration for ensuring continued isolation of contaminants from the accessible environment. Modified sulfur cement is a relatively new material and has only recently been applied as a binder for encapsulation of mixed wastes. Little data are available concerning its long-term durability. Therefore, a series of property evaluation tests for both binder and waste-binder combinations have been conducted to examine potential waste form performance under storage and disposal conditions. These tests include compressive strength, biodegradation, radiation stability, water immersion, thermal cycling, and leaching. Waste form compressive strength increased with ash waste loadings to 30.5 MPa at a maximum incinerator ash loading of 43 wt %. Biodegradation testing resulted in no visible microbial growth of either bacteria or fungi. Initial radiation stability testing did not reveal statistically significant deterioration in structural integrity. Results of 90 day water immersion tests were dependent on the type of ash tested. There were no statistically significant changes in compressive strength detected after completion of thermal cycle testing. Radionuclides from ash waste encapsulated in modified sulfur cement leached between 5 and 8 orders of magnitude slower than the leach index criterion established by the Nuclear Regulatory Commission (NRC) for low-level radioactive waste. Modified sulfur cement waste forms containing up to 43 wt % incinerator fly ash passed EPA Toxicity Characteristic Leaching Procedure (TCLP) criteria for lead and cadmium leachability. 11 refs., 2 figs., 5 tabs.

  5. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    SciTech Connect

    Naus, Dan J

    2007-02-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.

  6. Volvo Penta 4.3 GL E15 Emissions and Durability Test

    SciTech Connect

    Zoubul, G.; Cahoon, M.; Kolb, R.

    2011-10-01

    A new Volvo Penta carbureted 4.3 GL engine underwent emissions and dynamometer durability testing from break-in to expected end of life using an accelerated ICOMIA marine emissions cycle and E15 fuel. Only ethanol content was controlled. All aging used splash-blended E15 fuel. Exhaust emissions, exhaust gas temperature, torque, power, barometric pressure, air temperature, and fuel flow were measured at five intervals using site-blended E15 aging fuel and certification fuel (E0). The durability test cycle showed no noticeable impact on mechanical durability or engine power. Emissions performance degraded beyond the certification limit for this engine family, mostly occurring by 28% of expected life. Such degradation is inconsistent with prior experience. Comparisons showed that E15 resulted in lower CO and HC, but increased NOX, as expected for non-feedback-controlled carbureted engines with increased oxygen in the fuel. Fuel consumption also increased with E15 compared with E0. Throughout testing, poor starting characteristics were exhibited on E15 fuel for hot re-start and cold-start. Cranking time to start and smooth idle was roughly doubled compared with typical E0 operation. The carburetor was factory-set for lean operation to ensure emissions compliance. Test protocols did not include carburetor adjustment to account for increased oxygen in the E15 fuel.

  7. Prediction of glass durability as a function of environmental conditions

    SciTech Connect

    Jantzen, C M

    1988-01-01

    A thermodynamic model of glass durability is applied to natural, ancient, and nuclear waste glasses. The durabilities of over 150 different natural and man-made glasses, including actual ancient Roman and Islamic glasses (Jalame ca. 350 AD, Nishapur 10-11th century AD and Gorgon 9-11th century AD), are compared. Glass durability is a function of the thermodynamic hydration free energy, ..delta..G/sub hyd/, which can be calculated from glass composition and solution pH. The durability of the most durable nuclear waste glasses examined was /approximately/10/sup 6/ years. The least durable waste glass formulations were comparable in durability to the most durable simulated medieval window glasses of /approximately/10/sup 3/ years. In this manner, the durability of nuclear waste glasses has been interpolated to be /approximately/10/sup 6/ years and no less than 10/sup 3/ years. Hydration thermodynamics have been shown to be applicable to the dissolution of glass in various natural environments. Groundwater-glass interactions relative to geologic disposal of nuclear waste, hydration rind dating of obsidians, andor other archeological studies can be modeled, e.g., the relative durabilities of six simulated medieval window glasses have been correctly predicted for both laboratory (one month) and burial (5 years) experiments. Effects of solution pH on glass dissolution has been determined experimentally for the 150 different glasses and can be predicted theoretically by hydration thermodynamics. The effects of solution redox on dissolution of glass matrix elements such as SI and B have shown to be minimal. The combined effects of solution pH and Eh have been described and unified by construction of thermodynamically calculated Pourbaix (pH-Eh) diagrams for glass dissolution. The Pourbaix diagrams have been quantified to describe glass dissolution as a function of environmental conditions by use of the data derived from hydration thermodynamics. 56 refs., 7 figs.

  8. Weathering and durability of PV backsheets and impact on PV module performance

    NASA Astrophysics Data System (ADS)

    Gambogi, W.; Heta, Y.; Hashimoto, K.; Kopchick, J.; Felder, T.; MacMaster, S.; Bradley, A.; Hamzavytehraney, B.; Felix, V.; Aoki, T.; Stika, K.; Garreau-Illes, L.; Trout, T. J.

    2013-09-01

    Polymeric backsheets form the outer protective layer of most crystalline and multi-crystalline silicon cell photovoltaic panels. The mechanical, electrical, optical and chemical properties and durability of these backsheets are critical to the long term reliability, durability and safety of the photovoltaic modules. The stability of these backsheet properties is typically determined based on accelerated testing using individual stresses. However, the impact of multiple stresses applied sequentially or simultaneously can lead to changes in materials properties that are more predictive of performance in the field. An important consideration in the development of accelerated test protocols is the level and duration of the stress, including temperature variation, light intensity and spectral power distribution, humidity, rainfall and powered module current. In this paper, we discuss observations of the aging and degradation of solar panel from the field. Then how these changes correlate to accelerated testing results, and how accelerated tests can be modified to better match observations in the field.

  9. Effect of Sizings on the Durability of High Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Allred, Ronald E.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter, James K.

    2003-01-01

    To increase performance and durability of high-temperature composite for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide resins. Sizing commercially supplied on most carbon fiber are not compatible with polyimides. In this study, the chemistry of sizing on two high modulus carbon fiber (M40J and M60J, Tiray) was characterized. A continuous desizling system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room-temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the butter bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

  10. A nonlinear viscoelastic approach to durability predictions for polymer based composite structures

    NASA Technical Reports Server (NTRS)

    Brinson, Hal F.; Hiel, C. C.

    1990-01-01

    Current industry approaches for the durability assessment of metallic structures are briefly reviewed. For polymer based composite structures, it is suggested that new approaches must be adopted to include memory or viscoelastic effects which could lead to delayed failures that might not be predicted using current techniques. A durability or accelerated life assessment plan for fiber reinforced plastics (FRP) developed and documented over the last decade or so is reviewed and discussed. Limitations to the plan are outlined and suggestions to remove the limitations are given. These include the development of a finite element code to replace the previously used lamination theory code and the development of new specimen geometries to evaluate delamination failures. The new DCB model is reviewed and results are presented. Finally, it is pointed out that new procedures are needed to determine interfacial properties and current efforts underway to determine such properties are reviewed. Suggestions for additional efforts to develop a consistent and accurate durability predictive approach for FRP structures is outlined.

  11. High gain durable anti-reflective coating

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze'ev R.

    2016-07-26

    Disclosed herein are polysilsesquioxane-based anti-reflective coating (ARC) compositions, methods of preparation, and methods of deposition on a substrate. In one embodiment, the polysilsesquioxane of this disclosure is prepared in a two-step process of acid catalyzed hydrolysis of organoalkoxysilane followed by addition of tetralkoxysilane that generates silicone polymers with >40 mol % silanol based on Si-NMR. These high silanol siloxane polymers are stable and have a long shelf-life in polar organic solvents at room temperature. Also disclosed are low refractive index ARC made from these compositions with and without additives such as porogens, templates, thermal radical initiator, photo radical initiators, crosslinkers, Si--OH condensation catalyst and nano-fillers. Also disclosed are methods and apparatus for applying coatings to flat substrates including substrate pre-treatment processes, coating processes and coating curing processes including skin-curing using hot-air knives. Also disclosed are coating compositions and formulations for highly tunable, durable, highly abrasion-resistant functionalized anti-reflective coatings.

  12. Optical enhancing durable anti-reflective coating

    DOEpatents

    Maghsoodi, Sina; Varadarajan, Aravamuthan; Movassat, Meisam

    2016-07-05

    Disclosed herein are polysilsesquioxane based anti-reflective coating (ARC) compositions, methods of preparation, and methods of deposition on a substrate. In embodiments, the polysilsesquioxane of this disclosure is prepared in a two-step process of acid catalyzed hydrolysis of organoalkoxysilane followed by addition of tetralkoxysilane that generates silicone polymers with >40 mol % silanol based on Si-NMR. These high silanol siloxane polymers are stable and have a long shelf-life in the polar organic solvents at room temperature. Also disclosed are low refractive index ARC made from these compositions with and without additives such as porogens, templates, Si--OH condensation catalyst and/or nanofillers. Also disclosed are methods and apparatus for applying coatings to flat substrates including substrate pre-treatment processes, coating processes including flow coating and roll coating, and coating curing processes including skin-curing using hot-air knives. Also disclosed are coating compositions and formulations for highly tunable, durable, highly abrasion-resistant functionalized anti-reflective coatings.

  13. Durability of Alkali Activated Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Ellis, K.; Alharbi, N.; Matheu, P. S.; Varela, B.; Hailstone, R.

    2015-11-01

    The alkali activation of blast furnace slag has the potential to reduce the environmental impact of cementitious materials and to be applied in geographic zones where weather is a factor that negatively affects performance of materials based on Ordinary Portland Cement. The scientific literature provides many examples of alkali activated slag with high compressive strengths; however research into the durability and resistance to aggressive environments is still necessary for applications in harsh weather conditions. In this study two design mixes of blast furnace slag with mine tailings were activated with a potassium based solution. The design mixes were characterized by scanning electron microscopy, BET analysis and compressive strength testing. Freeze-thaw testing up to 100 freeze-thaw cycles was performed in 10% road salt solution. Our findings included compressive strength of up to 100 MPa after 28 days of curing and 120 MPa after freeze-thaw testing. The relationship between pore size, compressive strength, and compressive strength after freeze-thaw was explored.

  14. Durability Evaluation of Selected Solid Lubricating Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2001-01-01

    An investigation was conducted to examine the coefficients of friction, wear rates, and durability of bonded molybdenum disulfide (MoS2), magnetron-sputtered MoS2, ion-plated silver, ion-plated lead, magnetron-sputtered diamondlike carbon (MS DLC), and plasma-assisted, chemical-vapor-deposited DLC (PACVD DLC) films in sliding contact with 6-mm-diameter AISI 440C stainless steel balls. Unidirectional ball-on-disk sliding friction experiments were conducted with a load of 5.9 N and a sliding velocity of 0.2 m/s at room temperature in three environments: ultrahigh vacuum (vacuum pressure, 7 x 10(exp -7) Pa), humid air (relative humidity, approx. 20 percent), and dry nitrogen (relative humidity, less than 1 percent). The main criteria for judging the performance of the solid lubricating films were coefficient of friction and wear rate, which had to be less than 0.3 and on the order of 10(exp -6) cu mm/N.m or less, respectively. The bonded MoS2 and magnetron-sputtered MoS2 films met the criteria in all three environments. The ion-plated lead and silver films met the criteria only in ultrahigh vacuum but failed in humid air and in dry nitrogen. The MS DLC and PACVD DLC films met the requirements in humid air and dry nitrogen but failed in ultrahigh vacuum.

  15. The Association Between Household Consumer Durable Assets and Maternal Health-Seeking Behavior in Ghana.

    PubMed

    Ansong, Eric

    2015-01-01

    This article examined the association between household consumer durable assets and maternal health-seeking behavior. Several studies have suggested a relationship between households' socioeconomic status (SES) and health outcomes. However, SES is a multidimensional concept that encompasses variables, such as wealth, education, and income. By grouping these variables together as one construct, prior studies have not provided enough insight into possible independent associations with health outcomes. This study used data from the 2008 Ghana Demographic and Health Survey of 2,065 women aged between 15 and 49 years to examine the association between household consumer durables (a component of SES) and maternal health-seeking behavior in Ghana. Results from a set of generalized linear models indicated that household consumer durable assets were positively associated with four measures of maternal health-seeking behaviors, namely, seeking prenatal care from skilled health personnel, delivery by skilled birth attendant, place of delivery, and the number of antenatal visits. Also, households with more assets whose residents lived in urban areas were more likely to use skilled health personnel before and during delivery, and at an approved health facility, compared those who lived in rural areas. Implications for health interventions and policies that focus on the most vulnerable households are discussed.

  16. Preliminary investigation of magneto-rheological fluid durability in continuous slippage clutch

    NASA Astrophysics Data System (ADS)

    Desrosiers, J.-F.; Lucking Bigué, J.-P.; Denninger, M.; Julió, G.; Plante, J.-S.; Charron, F.

    2013-02-01

    Magneto-rheological (MR) devices, such as dampers, engine mounts and clutches, are now appearing in the ground vehicle industry. Although important work has been directed to assess the longevity of MR dampers, few studies have targeted the aspect of magnetorheological fluid (MRF) durability when used in continuous shear, such as in MR clutches. The objective of this research is to identify the degradation phenomena associated with MRF used in continuous shear and to understand the main causes and effects, in order to propose design improvements to enhance clutch durability. Experiments are conducted on two test benches in order to reproduce MRF aging in a controlled environment and to evaluate the proposed solutions. The effect of the operating conditions (shear rate, shear stress and temperature) on the long term degradation of the torque-current relationship is evaluated. Two degradation phenomena are identified: base oil expansion and particle oxidation. The dominant failure mode of the tested clutches is a MRF leakage resulting from the base oil expansion which occurs between 1.5 MJ/mL and 9 MJ/mL of dissipated energy depending of the operating conditions. Two solutions are proposed to extend clutch durability: 1- MRF circulation and 2-compliant elements.

  17. Rheological investigation of the shear strength, durability, and recovery of alginate rafts formed by antacid medication in varying pH environments.

    PubMed

    Elliott, Brooke M; Steckbeck, Kathleen E; Murray, Lisa R; Erk, Kendra A

    2013-11-30

    The mechanical response of alginate rafts formed by mixing liquid alginate antacid medication (Gaviscon Extra Strength Liquid Antacid) with acidic solutions was investigated by deforming isolated rafts in a shear rheometer. As rafts were deformed to varying magnitudes of applied strain, rheological parameters were identified and related to the overall strength, durability, and recoverability of rafts formed at different pH (1.1-1.7) and aging conditions (0.5-4 h). Rafts formed in the lowest acidity solutions (pH 1.4, 1.7) were elastically weak ( G'₀ = 60 , 42 Pa for un-aged raft) yet maintained their elasticity during applied shear deformation to large values of strain (γc∼90%, 50%, where G'≈G″), and displayed a low-to-moderate level of elastic recovery following large-strain deformation. Rafts formed in the highest acidity solution had the greatest strength ( G'₀ = 500 Pa for un-aged raft and 21.5 kPa for rafts after 0.5 h of aging), reduced durability (γc∼2.5%, independent of aging), and displayed the greatest recoverability. A trade-off existed between un-aged raft strength and durability while recovery was dependent on durability, solution pH, and age. Rheometry-based evaluations of alginate rafts could be used for the informed design of future gastric retention and antacid products. PMID:24095816

  18. Durability of optically variable devices on bank notes

    NASA Astrophysics Data System (ADS)

    Bartz, William J.

    2002-04-01

    Currency producers are facing dual marketplace demands to increase bank note circulation life and to employ increasingly effective security features against counterfeiting. Diffractive optically variable devices such as foil patches, stripes and windowed thread have become popular security features used for bank notes throughout the world, but historically have suffered in their ability to match the durability of the bank note substrate itself. A study to find a durable, diffractive OVD led to the development of a windowed-thread feature designed to pass stringent durability criteria for laundry, chemical soak and other performance tests. Diffractive-film production methods, demetallization techniques, thread construction and applied coatings were key factors in achieving this durability.

  19. Thermodynamic model of natural, medieval and nuclear waste glass durability

    SciTech Connect

    Jantzen, C.M.; Plodinec, M.J.

    1983-01-01

    A thermodynamic model of glass durability based on hydration of structural units has been applied to natural glass, medieval window glasses, and glasses containing nuclear waste. The relative durability predicted from the calculated thermodynamics correlates directly with the experimentally observed release of structural silicon in the leaching solution in short-term laboratory tests. By choosing natural glasses and ancient glasses whose long-term performance is known, and which bracket the durability of waste glasses, the long-term stability of nuclear waste glasses can be interpolated among these materials. The current Savannah River defense waste glass formulation is as durable as natural basalt from the Hanford Reservation (10/sup 6/ years old). The thermodynamic hydration energy is shown to be related to the bond energetics of the glass. 69 references, 2 figures, 1 table.

  20. Durability of Bricks Coated with Red mud Based Geopolymer Paste

    NASA Astrophysics Data System (ADS)

    Singh, Smita; Basavanagowda, S. N.; Aswath, M. U.; Ranganath, R. V.

    2016-09-01

    The present study is undertaken to assess the durability of concrete blocks coated with red mud - fly ash based geopolymer paste. Concrete blocks of size 200 x 200 x 100mm were coated with geopolymer paste synthesized by varying the percentages of red mud and fly ash. Uncoated concrete blocks were also tested for the durability for comparison. In thermal resistance test, the blocks were subjected to 600°C for an hour whereas in acid resistance test, they were kept in 5% sulphuric acid solution for 4 weeks. The specimens were thereafter studied for surface degradation, strength loss and weight loss. Pastes with red mud percentage greater than 50% developed lot of shrinkage cracks. The blocks coated with 30% and 50% red mud paste showed better durability than the other blocks. The use of blocks coated with red mud - fly ash geopolymer paste improves the aesthetics, eliminates the use of plaster and improves the durability of the structure.

  1. Nanocomposites for Improved Physical Durability of Porous PVDF Membranes

    PubMed Central

    Lai, Chi Yan; Groth, Andrew; Gray, Stephen; Duke, Mikel

    2014-01-01

    Current commercial polymer membranes have shown high performance and durability in water treatment, converting poor quality waters to higher quality suitable for drinking, agriculture and recycling. However, to extend the treatment into more challenging water sources containing abrasive particles, micro and ultrafiltration membranes with enhanced physical durability are highly desirable. This review summarises the current limits of the existing polymeric membranes to treat harsh water sources, followed by the development of nanocomposite poly(vinylidene fluoride) (PVDF) membranes for improved physical durability. Various types of nanofillers including nanoparticles, carbon nanotubes (CNT) and nanoclays were evaluated for their effect on flux, fouling resistance, mechanical strength and abrasion resistance on PVDF membranes. The mechanisms of abrasive wear and how the more durable materials provide resistance was also explored. PMID:24957121

  2. Durability of hydrophobic coatings for superhydrophobic aluminum oxide

    NASA Astrophysics Data System (ADS)

    Jenner, Elliot; Barbier, Charlotte; D'Urso, Brian

    2013-10-01

    Robust and easily produced superhydrophobic surfaces are of great interest for mechanical applications, including drag reduction and MEMS. We produce novel superhydrophobic surfaces with several different coatings and tested the durability of each of these coatings with respect to long term immersion in water in order to determine the most long-lasting surface preparation. A pair of combinations of spin on polymers, surface features, and adhesion promoters was found that provide long term durability.

  3. Durability of Hydrophobic Coatings for Superhydrophobic Aluminum Oxide

    SciTech Connect

    Jenner, Elliot; Barbier, Charlotte N; D'Urso, Brian R

    2013-01-01

    Robust and easily produced Superhydrophobic surfaces are of great interest for mechanical applications, including drag reduction and MEMS. We produce novel superhydrophobic surfaces with several different coatings and tested the durability of each of these coatings with respect to long term immersion in water in order to determine the most long-lasting surface preparation. A pair of combinations of spin on polymers, surface features, and adhesion promoters was found that provide long term durability.

  4. High-durability infrared transparent coatings

    NASA Astrophysics Data System (ADS)

    Goldman, Lee M.; Tustison, Randal W.

    1994-09-01

    LWIR windows are exposed to harsh conditions during high speed flight. These include high speed rain drop impact, sand abrasion, corrosion, and aerothermodynamic load. With the possible exception of diamond, there are no LWIR transparent window/dome materials which can withstand these various environments. Rain erosion protective (REP) and oxide based abrasion resistant/oxidation resistant durable antireflection (DAR) coatings have been developed for LWIR applications. These coatings have demonstrated a substantial degree of raindrop impact protection (i.e., damage threshold velocities of approximately Mach 1, for 2 mm equivalent waterdrop impacts at normal incidence). The combination of REP + DAR coating have also demonstrated excellent resistance to sand abrasion in simulated flight environments. The high degree of abrasion resistance makes the DAR coatings applicable to ground based systems, using ZnS and ZnSe, windows as well. An additional advantage of the Raytheon REP + DAR combination is that they are transparent from the visible to the LWIR (8 to 12 mm), making them suitable for applications requiring broadband transparency. Furthermore, the DAR coatings have protected ZnS substrates from oxidation at temperatures up to 1000 degree(s)C. The combination of ZnS REP coating and DAR coating are ideally suited for protecting high speed LWIR missiles from rain and sand damage during captive carry, as well as protecting the dome/window from oxidation during high speed flight. Data are presented to demonstrate the rain/sand and oxidation protection provided by these coatings. The REP and DAR coatings have been scaled up to coat windows and domes for far infrared applications.

  5. Bonding Durability of Four Adhesive Systems

    PubMed Central

    Seyed Tabai, Elaheh; Mohammadi Basir, Mahshid

    2015-01-01

    Objectives: This study aimed to compare the durability of four adhesive systems by assessing their microtensile bond strength (MTBS) and microleakage during six months of water storage. Materials and Methods: A total of 128 human third molars were used. The adhesives tested were Scotch Bond Multipurpose (SBMP), Single Bond (SB), Clearfil-SE bond (CSEB), and All-Bond SE (ABSE). After sample preparation for MTBS testing, the microspecimens were subjected to microtensile tester after one day and six months of water storage. For microleakage evaluation, facial and lingual class V cavities were prepared and restored with composite. After thermocycling, microleakage was evaluated. Bond strength values were subjected to one-way ANOVA and Tamhane’s test, and the microleakage data were analyzed by the Kruskal-Wallis, Dunn, Mann Whitney and Wilcoxon tests (P<0.05). Results: Single Bond yielded the highest and ABSE yielded the lowest bond strength at one day and six months. Short-term bond strength of SBMP and CSEB was similar. After six months, a significant decrease in bond strength was observed in ABSE and SBMP groups. At one day, ABSE showed the highest microleakage at the occlusal margin; however, at the gingival margin, there was no significant difference among groups. Long-term microleakage of all groups at the occlusal margins was similar, whilst gingival margins of SBMP and SB showed significantly higher microleakage. Conclusion: The highest MTBS and favorable sealability were obtained by Clearfil SE bond. Water storage had no effect on microleakage of self-etch adhesives at the gingival margin or MTBS of CSEB and SB. PMID:27123015

  6. Durability testing of advanced catalysts and catalyst supports for gas turbine engine combustors

    NASA Technical Reports Server (NTRS)

    Heck, R. M.; Chang, M.; Hess, H. W.; Mroz, T. S.

    1979-01-01

    The paper presents new information on the durability of a CATCOM catalyst operating at low-emission combustion temperatures (about 1527 K) with a liquid fuel, No. 2 diesel. Information on the activity of No. 2 diesel after 1000 hr of aging is given. In addition, a unique in situ activity test developed for monitoring the subtle changes in the catalyst activity of the CATCOM catalyst is also detailed. The study demonstrated the feasibility of using a CATCOM catalyst in catalytically supported thermal combustion for extended operating periods

  7. Re-evaluation of Pleistocene and Holocene long bone robusticity trends with regards to age-at-death estimates and size standardization procedures.

    PubMed

    Friedl, Lukáš; Eisová, Stanislava; Holliday, Trenton W

    2016-08-01

    Long-term trends in robusticity of lower limb bones in the genus Homo through the Pleistocene until the present have been proposed, which have been interpreted as a consequence of decreasing levels of mobility and activity patterns, changes in lifestyle, and environmental factors. There has also long been evidence that skeletal strength increases over an individual's lifespan. This increase is caused by continuous bone remodeling that optimizes the structure of a bone to resist mechanical loadings and creates a balance between endosteal resorption and subperiosteal apposition. However, none of the previous studies of temporal trends in robusticity has considered both processes and analyzed how individual age-related robusticity might influence higher-level temporal trends. This paper therefore explores temporal trends in robusticity of lower limb long bones within the genus Homo and considers how individual ages-at-death can confound published evolutionary trends, given the fact that some aspects of relative bone strength tend to increase over individual lifespans. Cross-sectional diaphyseal properties of the midshaft and proximal femur and midshaft tibia of Pleistocene and early Holocene individuals, together with data on age-at-death are used to analyze changes in relative bone strength relative to individuals' ages and evolutionary time. The results show increasing bone strength in adulthood until the fourth decade and then a slight decrease, an observation that conforms to previously published results on recent human populations. However, no significant impact of age-at-death on the trends along an evolutionary trajectory has been detected. The evolutionary trends in femoral and tibial relative strength can be described as fluctuating, probably as a consequence of changing mobility patterns, environmentally and technologically influenced behaviors, and demographic processes. The differences between evolutionary trends published in several studies are explained

  8. Reliability and durability of fiber grating sensors in structural monitoring applications

    NASA Astrophysics Data System (ADS)

    Sennhauser, Urs J.; Broennimann, Rolf; Mauron, Pascal; Nellen, Philipp M.

    1997-09-01

    There is strong interest to develop fiber-optical sensing systems for long term surveillance and structural monitoring. Although many detection schemes have been proposed, industrial acceptance of optical fibers as validated replacement of other sensors is limited. Low cost manufacturability, reliability, and long term stability are very important for usability in concrete and composite material structures. Lifetime for major structures in civil engineering of 50 - 100 years are very demanding on the sensors and require accurate aging models and test data to demonstrate their reliability and durability. Acceleration factors of several orders of magnitude can be achieved under reasonable testing conditions depending on temperature, mechanical stress, humidity, chemical environment and activation energy of the damaging process. We report on accelerated aging tests and failure mechanisms of optical fibers and Bragg gratings at elevated temperature, humidity and mechanical stress. Aging behavior is discussed and results from field measurements of large civil structures are presented.

  9. Durability of Class I American College of Cardiology/American Heart Association Clinical Practice Guideline Recommendations

    PubMed Central

    Neuman, Mark D.; Goldstein, Jennifer N.; Cirullo, Michael A.; Schwartz, J. Sanford

    2015-01-01

    IMPORTANCE Little is known regarding the durability of clinical practice guideline recommendations over time. OBJECTIVE To characterize variations in the durability of class I (“procedure/treatment should be performed/administered”) American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations. DESIGN, SETTING, AND PARTICIPANTS Textual analysis by 4 independent reviewers of 11 guidelines published between 1998 and 2007 and revised between 2006 and 2013. MAIN OUTCOMES AND MEASURES We abstracted all class I recommendations from the first of the 2 most recent versions of each guideline and identified corresponding recommendations in the subsequent version. We classified recommendations replaced by less determinate or contrary recommendations as having been downgraded or reversed; we classified recommendations for which no corresponding item could be identified as having been omitted. We tested for differences in the durability of recommendations according to guideline topic and underlying level of evidence using bivariable hypothesis tests and conditional logistic regression. RESULTS Of 619 index recommendations, 495 (80.0%; 95%CI, 76.6%–83.1%) were retained in the subsequent guideline version, 57 (9.2%; 95%CI, 7.0%–11.8%) were downgraded or reversed, and 67 (10.8%; 95%CI, 8.4%–13.3%) were omitted. The percentage of recommendations retained varied across guidelines from 15.4%(95%CI, 1.9%–45.4%) to 94.1%(95%CI, 80.3%–99.3%; P < .001). Among recommendations with available information on level of evidence, 90.5%(95%CI, 83.2%–95.3%) of recommendations supported by multiple randomized studies were retained, vs 81.0% (95%CI, 74.8%–86.3%) of recommendations supported by 1 randomized trial or observational data and 73.7%(95% CI, 65.8%–80.5%) of recommendations supported by opinion (P = .001). After accounting for guideline-level factors, the probability of being downgraded, reversed, or omitted was greater for

  10. Bases for extrapolating materials durability in fuel storage pools

    SciTech Connect

    Johnson, A.B. Jr.

    1994-12-01

    A major body of evidence indicates that zirconium alloys have the most consistent and reliable durability in wet storage, justifying projections of safe wet storage greater than 50 y. Aluminum alloys have the widest range of durabilities in wet storage; systematic control and monitoring of water chemistry have resulted in low corrosion rates for more than two decades on some fuels and components. However, cladding failures have occurred in a few months when important parameters were not controlled. Stainless steel is extremely durable when stress, metallurgical and water chemistry factors are controlled. LWR SS cladding has survived for 25 y in wet storage. However, sensitized, stressed SS fuels and components have seriously degraded in fuel storage pools (FSPs) at {approximately} 30 C. Satisfactory durability of fuel assembly and FSP component materials in extended wet storage requires investments in water quality management and surveillance, including chemical and biological factors. The key aspect of the study is to provide storage facility operators and other decision makers a basis to judge the durability of a given fuel type in wet storage as a prelude to basing other fuel management plans (e.g. dry storage) if wet storage will not be satisfactory through the expected period of interim storage.

  11. Relative sliding durability of candidate high temperature fiber seal materials

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Steinetz, Bruce M.

    1992-01-01

    The relative sliding durability behavior of six candidate ceramic fibers for high temperature sliding seal applications is reviewed and compared. Pin on disk tests were used to evaluate potential seal materials by sliding a tow or bundle of the candidate ceramic fiber against a superalloy test disk. Tests were conducted in air under a 2.65 N load, at a sliding velocity of 0.025 m/sec and at temperatures from 25 to 900 C. Friction was measured during the tests and fiber wear, indicated by the extent of fibers broken in the tow or bundle, was measured at the end of each test. For most of the fibers, friction and wear increase with test temperature. The relative fiber durability ranking correlates with tensile strength, indicating that tensile data, which is more readily available than sliding durability data, may be useful in predicting fiber wear behavior under various conditions. A dimensional analysis of the wear data shows that the fiber durability is related to a dimensionless durability ratio which represents the ratio of the fiber strength to the fiber stresses imposed by sliding. The analysis is applicable to fibers with similar diameters and elastic moduli. Based upon the results of the research program, three fiber candidates are recommended for further study as potential seal materials. They are a silicon based complex carbide-oxide fiber, an alumina-boria-silica and an aluminosilicate fiber.

  12. Stirling engine - Approach for long-term durability assessment

    NASA Technical Reports Server (NTRS)

    Tong, Michael T.; Bartolotta, Paul A.; Halford, Gary R.; Freed, Alan D.

    1992-01-01

    The approach employed by NASA Lewis for the long-term durability assessment of the Stirling engine hot-section components is summarized. The approach consists of: preliminary structural assessment; development of a viscoplastic constitutive model to accurately determine material behavior under high-temperature thermomechanical loads; an experimental program to characterize material constants for the viscoplastic constitutive model; finite-element thermal analysis and structural analysis using a viscoplastic constitutive model to obtain stress/strain/temperature at the critical location of the hot-section components for life assessment; and development of a life prediction model applicable for long-term durability assessment at high temperatures. The approach should aid in the provision of long-term structural durability and reliability of Stirling engines.

  13. Mechanical durability and combustion characteristics of pellets from biomass blends.

    PubMed

    Gil, M V; Oulego, P; Casal, M D; Pevida, C; Pis, J J; Rubiera, F

    2010-11-01

    Biofuel pellets were prepared from biomass (pine, chestnut and eucalyptus sawdust, cellulose residue, coffee husks and grape waste) and from blends of biomass with two coals (bituminous and semianthracite). Their mechanical properties and combustion behaviour were studied by means of an abrasion index and thermogravimetric analysis (TGA), respectively, in order to select the best raw materials available in the area of study for pellet production. Chestnut and pine sawdust pellets exhibited the highest durability, whereas grape waste and coffee husks pellets were the least durable. Blends of pine sawdust with 10-30% chestnut sawdust were the best for pellet production. Blends of cellulose residue and coals (<20%) with chestnut and pine sawdusts did not decrease pellet durability. The biomass/biomass blends presented combustion profiles similar to those of the individual raw materials. The addition of coal to the biomass in low amounts did not affect the thermal characteristics of the blends. PMID:20605093

  14. Durability/life of fiber composites in hygrothermomechanical environments

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1982-01-01

    Statistical analysis and multiple regression were used to determine and quantify the significant hygrothermomechanical variables which influence the tensile durability/life (cycle loading, fatigue) of boron-fiber/epoxy-matrix (B/E) and high-modulus-fiber/epoxy-matrix (HMS/E) composites. The use of the multiple regression analysis reduced the variables from fifteen, assumed initially, to six or less with a probability of greater than 0.999. The reduced variables were used to derive predictive models for compression and intralaminar shear durability/life of B/E and HMS/E composites assuming isoparametric fatigue behavior. The predictive models were subsequently generalized to predict the durability/life of graphite/fiber-r generalized model is of simple form, predicts conservative values compared with measured data and should be adequate for use in preliminary designs. Previously announced in STAR as N82-14287

  15. Durability/life of fiber composites in hygrothermomechanical environments

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1981-01-01

    Statistical analysis and multiple regression were used to determine and quantify the significant hygrothermomechanical variables which infuence the tensile durability/life (cycle loading, fatigue) of boron-fiber/epoxy-matrix (B/E) and high-modulus-fiber/epoxy-matrix (HMS/E) composites. The use of the multiple regression analysis reduced the variables from fifteen, assumed initially, to six or less with a probability of greater than 0.999. The reduced variables were used to derive predictive models for compression an intralaminar shear durability/life of B/E and HMS/E composites assuming isoparametric fatigue behavior. The predictive models were subsequently generalized to predict the durability/life of graphite-fiber-r generalized model is of simple form, predicts conservative values compared with measured data and should be adequate for use in preliminary designs.

  16. Building, Testing, and Post Test Analysis of Durability Heat Pipe No.6

    SciTech Connect

    MOSS, TIMOTHY A.

    2002-03-01

    The Solar Thermal Program at Sandia supports work developing dish/Stirling systems to convert solar energy into electricity. Heat pipe technology is ideal for transferring the energy of concentrated sunlight from the parabolic dish concentrators to the Stirling engine heat tubes. Heat pipes can absorb the solar energy at non-uniform flux distributions and release this energy to the Stirling engine heater tubes at a very uniform flux distribution thus decoupling the design of the engine heater head from the solar absorber. The most important part of a heat pipe is the wick, which transports the sodium over the heated surface area. Bench scale heat pipes were designed and built to more economically, both in time and money, test different wicks and cleaning procedures. This report covers the building, testing, and post-test analysis of the sixth in a series of bench scale heat pipes. Durability heat pipe No.6 was built and tested to determine the effects of a high temperature bakeout, 950 C, on wick corrosion during long-term operation. Previous tests showed high levels of corrosion with low temperature bakeouts (650-700 C). Durability heat pipe No.5 had a high temperature bakeout and reflux cleaning and showed low levels of wick corrosion after long-term operation. After testing durability heat pipe No.6 for 5,003 hours at an operating temperature of 750 C, it showed low levels of wick corrosion. This test shows a high temperature bakeout alone will significantly reduce wick corrosion without the need for costly and time consuming reflux cleaning.

  17. A retrospective study of hearing, speech and language function in children with clefts following palatoplasty and veloplasty procedures at 18-24 months of age.

    PubMed

    Schönweiler, R; Lisson, J A; Schönweiler, B; Eckardt, A; Ptok, M; Tränkmann, J; Hausamen, J E

    1999-11-01

    Many cleft palate teams currently schedule palatoplasty and veloplasty within the child's first year of life. At Hannover Medical School, palatoplasty and veloplasty are performed at approximately 18-24 months of age. It was questioned which speech and language outcome was achieved and whether it may be influenced by: (1) type and extent of the clefts; (2) velopharyngeal inadequacy; and (3) hearing disorders. A retrospective evaluation of data collected from 1985 to 1993 was performed summarizing receptive and expressive speech and language skills of 370 children aged 4.5 years. Cleft types were unilateral cleft lip and palate (UCLP, 30.0%), bilateral cleft lip and palate (BCLP, 28.7%), cleft hard and soft palate (CP, 21.6%), cleft soft palate (cleft velum, CV, 10.8%), cleft lip and alveolus (CLA, 5.8%) and submucous clefts (SUB, 3.2%). n = 86 had constant normal hearing, and n = 284 had conductive hearing loss > 20 dB (500-4000 Hz). Severe developmental phonology errors were found in 30-50% of children with repaired cleft palate and in less than 8% of patients with CLA and SUB. Posterior compensatory misarticulation was below 15% in the groups UCLP, BCLP, CP, CV and SUB. Nasal resonance and air emission was nearly normal in CLA, but was increased in 27% to 38% of the other cleft types. Children with conductive hearing loss had significantly more and severely affected phonology, morphology, syntax, vocabulary, language comprehension, and auditory perception than normal hearing children. Findings indicated that speech and language function in CLP patients were predominantly related to the hearing status. PMID:10595666

  18. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Baltich, L.K.

    1987-02-23

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  19. Glycogen with short average chain length enhances bacterial durability

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Wise, Michael J.

    2011-09-01

    Glycogen is conventionally viewed as an energy reserve that can be rapidly mobilized for ATP production in higher organisms. However, several studies have noted that glycogen with short average chain length in some bacteria is degraded very slowly. In addition, slow utilization of glycogen is correlated with bacterial viability, that is, the slower the glycogen breakdown rate, the longer the bacterial survival time in the external environment under starvation conditions. We call that a durable energy storage mechanism (DESM). In this review, evidence from microbiology, biochemistry, and molecular biology will be assembled to support the hypothesis of glycogen as a durable energy storage compound. One method for testing the DESM hypothesis is proposed.

  20. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Berggren, M.H.

    1989-05-02

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  1. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Baltich, L.K.; Berggren, M.H.

    1987-05-18

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  2. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Silaban, A.; Harrison, D.P. . Dept. of Chemical Engineering)

    1989-05-02

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such as size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  3. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Berggren, M.H.

    1988-11-14

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  4. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Baltich, L.K.; Berggren, M.H.

    1987-08-28

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  5. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Berggren, M.H.

    1988-08-19

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  6. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Berggren, M.H.

    1989-03-06

    AMAX Research Development Center (AMAX R D) has been investigating methods for enhancing the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For the present program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such As size, strength, and specific surface area during 10 cycles of sulfidation and oxidation.

  7. Durability of Ti-6Al-4V/LaRC-PETI-5 adhesive bonded system for HSCT applications

    SciTech Connect

    Parvatareddy, H.; Pasricha, A.; Dillard, D.A.; Dillard, J.G.

    1996-12-31

    Structural adhesive joints are being widely used and studied as alternatives to conventional fasteners in the aerospace, automotive, and other industries. Adhesive bonding offers advantages such as lower weight and lower manufacturing costs. Furthermore, high performance adhesives which are currently being synthesized (e.g. epoxies, phenolics, acrylics, thermoplastic polyimides) offer other useful properties such as higher modulus, higher toughness, and stability at high temperatures. In the present study, the durability of the Ti-6Al-4V/LaRC PETI-5 adhesive bonded system is being evaluated utilizing double cantilever beam (DCB) fracture specimens. These DCB tests have been used extensively to study adhesive joints. The current study is part of a comprehensive study to develop a durable material system for application in the proposed mach 2.4 high speed civil transport (HSCT) aircraft. According to the design criteria, the material system to be used on the aircraft should be durable for over 60,000 hours of flight encountering temperatures during flight in the range of 177{degrees}C. Physical aging and chemical aging of the adhesive material are some of the important issues which have to be evaluated and taken into consideration for predicting the bond durability. In order to simulate the service environment conditions of the HSCT, the Ti-6Al-4V/LaRC PETI-5 bonds were aged in one of three temperatures; 150, 177, and 204{degrees}C, at one of three different environments; atmospheric air, and reduced air pressures of 2 psi air (13.8 KPa) and 0.2 psi air (1.38 KPa).

  8. Textile for heart valve prostheses: fabric long-term durability testing.

    PubMed

    Heim, Frederic; Durand, Bernard; Chakfe, Nabil

    2010-01-01

    The rapid developments and success in percutaneous vascular surgery over the last two decades with the now common stent grafts implantation, make the noninvasive surgery technique today attractive even for heart valve replacement. Less traumatic for the patient and also less time consuming, percutaneous heart valve replacement is however at its beginning and restricted to end of life patients. The noninvasive procedure expects from the heart valve prosthesis material to be resistant and adapted to folding requirements of the implantation process (catheter). Polyester fabric could be a suited material for heart valve implanted percutaneously. Highly flexible and resistant, polyester fabric proved to be well adapted to the dynamic behavior of a valve and polyester (Dacron) is also widely used for vascular grafts implantation and shows good biocompatibility and durability. However, today there's no data available on long-term durability of fabric used as heart valve material. The purpose of this work is to study the long term behavior of a microdenier polyester fabric construction under combined in vitro flexure and tension fatigue stress. In the novel in vitro testing technique presented, a fabric specimen was subjected to combined flexural and tensile fatigue generated by fluid flow under physiological pressure conditions. The results obtained show how flexural properties change with fatigue time, which reflects directly on the suitability of a fabric in such devices. It was also observed that these fabric structural changes directly influence the in vitro behavior of the textile heart valve prosthesis.

  9. Laboratory Evaluations of Durability of Southern Pine Pressure Treated With Extractives From Durable Wood Species.

    PubMed

    Kirker, G T; Bishell, A B; Lebow, P K

    2016-02-01

    Extracts from sawdust of four naturally durable wood species [Alaskan yellow cedar, AYC, Cupressus nootkanansis D. Don 1824; eastern red cedar, ERC, Juniperus virginiana L.; honey mesquite, HM, Prosopis glandulosa Torr.; and black locust, BL, Robinia pseudoacacia L.] were used to treat southern pine, Pt, Pinus taeda L. sapwood blocks. Extractive treated blocks were evaluated for decay resistance in standard soil bottle fungal assays challenged with brown and white rot decay fungi. Results showed that extractives did impart some improvement to decay resistance of Pt blocks. BL- and HM-treated Pt blocks were also used in choice and no-choice assays to determine feeding preference and damage by eastern subterranean termites (Reticulitermes flavipes) Kollar. Minimal feeding on treated blocks was seen in both choice and no-choice assays. In choice assays, there was similar mortality between HM and BL arenas; however, in no-choice assays, complete mortality was recorded for HM-treated Pt and high mortality was seen with BL-treated Pt. Subsequent dose mortality termite assays showed HM to be effective in killing R. flavipes at low concentrations. Both HM and BL show promise as deterrents or termiticidal protectants and will be further evaluated in field studies. PMID:26494706

  10. Laboratory Evaluations of Durability of Southern Pine Pressure Treated With Extractives From Durable Wood Species.

    PubMed

    Kirker, G T; Bishell, A B; Lebow, P K

    2016-02-01

    Extracts from sawdust of four naturally durable wood species [Alaskan yellow cedar, AYC, Cupressus nootkanansis D. Don 1824; eastern red cedar, ERC, Juniperus virginiana L.; honey mesquite, HM, Prosopis glandulosa Torr.; and black locust, BL, Robinia pseudoacacia L.] were used to treat southern pine, Pt, Pinus taeda L. sapwood blocks. Extractive treated blocks were evaluated for decay resistance in standard soil bottle fungal assays challenged with brown and white rot decay fungi. Results showed that extractives did impart some improvement to decay resistance of Pt blocks. BL- and HM-treated Pt blocks were also used in choice and no-choice assays to determine feeding preference and damage by eastern subterranean termites (Reticulitermes flavipes) Kollar. Minimal feeding on treated blocks was seen in both choice and no-choice assays. In choice assays, there was similar mortality between HM and BL arenas; however, in no-choice assays, complete mortality was recorded for HM-treated Pt and high mortality was seen with BL-treated Pt. Subsequent dose mortality termite assays showed HM to be effective in killing R. flavipes at low concentrations. Both HM and BL show promise as deterrents or termiticidal protectants and will be further evaluated in field studies.

  11. 40 CFR Appendix I to Subpart V of... - Recommended Test Procedures and Test Criteria and Recommended Durability Procedures To...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... regulated power supply. b. Record dwell angle and open-circuit output voltage at 300 and 500 distributor rpm... test system with a power supply regulated at 14 ±0.5 V DC for a 12V system. d. The secondary portion of... the primary of the test system with a power supply regulated at 14 ±0.5V DC for 12V system. d....

  12. 40 CFR Appendix I to Subpart V of... - Recommended Test Procedures and Test Criteria and Recommended Durability Procedures To...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... regulated power supply. b. Record dwell angle and open-circuit output voltage at 300 and 500 distributor rpm... test system with a power supply regulated at 14 ±0.5 V DC for a 12V system. d. The secondary portion of... the primary of the test system with a power supply regulated at 14 ±0.5V DC for 12V system. d....

  13. Recent advances in the mechanical durability of superhydrophobic materials.

    PubMed

    Milionis, Athanasios; Loth, Eric; Bayer, Ilker S

    2016-03-01

    Large majority of superhydrophobic surfaces have very limited mechanical wear robustness and long-term durability. This problem has restricted their utilization in commercial or industrial applications and resulted in extensive research efforts on improving resistance against various types of wear damage. In this review, advances and developments since 2011 in this field will be covered. As such, we summarize progress on fabrication, design and understanding of mechanically durable superhydrophobic surfaces. This includes an overview of recently published diagnostic techniques for probing and demonstrating tribo-mechanical durability against wear and abrasion as well as other effects such as solid/liquid spray or jet impact and underwater resistance. The review is organized in terms of various types of mechanical wear ranging from substrate adhesion, tangential surface abrasion, and dynamic impact to ultrasonic processing underwater. In each of these categories, we highlight the most successful approaches to produce robust surfaces that can maintain their non-wetting state after the wear or abrasive action. Finally, various recommendations for improvement of mechanical wear durability and its quantitative evaluation are discussed along with potential future directions towards more systematic testing methods which will also be acceptable for industry.

  14. A Simplified Diagnostic Method for Elastomer Bond Durability

    NASA Technical Reports Server (NTRS)

    White, Paul

    2009-01-01

    A simplified method has been developed for determining bond durability under exposure to water or high humidity conditions. It uses a small number of test specimens with relatively short times of water exposure at elevated temperature. The method is also gravimetric; the only equipment being required is an oven, specimen jars, and a conventional laboratory balance.

  15. Measuring Happiness: From Fluctuating Happiness to Authentic–Durable Happiness

    PubMed Central

    Dambrun, Michaël; Ricard, Matthieu; Després, Gérard; Drelon, Emilie; Gibelin, Eva; Gibelin, Marion; Loubeyre, Mélanie; Py, Delphine; Delpy, Aurore; Garibbo, Céline; Bray, Elise; Lac, Gérard; Michaux, Odile

    2012-01-01

    On the basis of the theoretical distinction between self-centeredness and selflessness (Dambrun and Ricard, 2011), the main goal of this research was to develop two new scales assessing distinct dimensions of happiness. By trying to maximize pleasures and to avoid displeasures, we propose that a self-centered functioning induces a fluctuating happiness in which phases of pleasure and displeasure alternate repeatedly (i.e., Fluctuating Happiness). In contrast, a selfless psychological functioning postulates the existence of a state of durable plenitude that is less dependent upon circumstances but rather is related to a person’s inner resources and abilities to deal with whatever comes his way in life (i.e., Authentic–Durable Happiness). Using various samples (n = 735), we developed a 10-item Scale measuring Subjective Fluctuating Happiness (SFHS) and a 13-item scale assessing Subjective Authentic–Durable Happiness (SA–DHS). Results indicated high internal consistencies, satisfactory test–retest validities, and adequate convergent and discriminant validities with various constructs including a biological marker of stress (salivary cortisol). Consistent with our theoretical framework, while self-enhancement values were related only to fluctuating happiness, self-transcendence values were related only to authentic–durable happiness. Support for the distinction between contentment and inner-peace, two related markers of authentic happiness, also was found. PMID:22347202

  16. Structural Integrity and Durability of Reusable Space Propulsion Systems

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A two-day conference on the structural integrity and durability of reusable space propulsion systems was held on May 12 and 13, 1987, at the NASA Lewis research Center. Aerothermodynamic loads; instrumentation; fatigue, fracture, and constitutive modeling; and structural dynamics were discussed.

  17. Recent advances in the mechanical durability of superhydrophobic materials.

    PubMed

    Milionis, Athanasios; Loth, Eric; Bayer, Ilker S

    2016-03-01

    Large majority of superhydrophobic surfaces have very limited mechanical wear robustness and long-term durability. This problem has restricted their utilization in commercial or industrial applications and resulted in extensive research efforts on improving resistance against various types of wear damage. In this review, advances and developments since 2011 in this field will be covered. As such, we summarize progress on fabrication, design and understanding of mechanically durable superhydrophobic surfaces. This includes an overview of recently published diagnostic techniques for probing and demonstrating tribo-mechanical durability against wear and abrasion as well as other effects such as solid/liquid spray or jet impact and underwater resistance. The review is organized in terms of various types of mechanical wear ranging from substrate adhesion, tangential surface abrasion, and dynamic impact to ultrasonic processing underwater. In each of these categories, we highlight the most successful approaches to produce robust surfaces that can maintain their non-wetting state after the wear or abrasive action. Finally, various recommendations for improvement of mechanical wear durability and its quantitative evaluation are discussed along with potential future directions towards more systematic testing methods which will also be acceptable for industry. PMID:26792021

  18. Ancient analogues concerning stability and durability of cementitious wasteform

    SciTech Connect

    Jiang, W.; Roy, D.M.

    1994-12-31

    The history of cementitious materials goes back to ancient times. The Greeks and Romans used calcined limestone and later developed pozzolanic cement by grinding together lime and volcanic ash called {open_quotes}pozzolan{close_quotes} which was first found near Port Pozzuoli, Italy. The ancient Chinese used lime-pozzolanic mixes to build the Great Wall. The ancient Egyptians used calcined impure gypsum to build the Great Pyramid of Cheops. The extraordinary stability and durability of these materials has impressed us, when so much dramatically damaged infrastructure restored by using modern portland cement now requires rebuilding. Stability and durability of cementitious materials have attracted intensive research interest and contractors` concerns, as does immobilization of radioactive and hazardous industrial waste in cementitious materials. Nuclear waste pollution of the environment and an acceptable solution for waste management and disposal constitute among the most important public concerns. The analogy of ancient cementitious materials to modern Portland cement could give us some clues to study their stability and durability. This present study examines selected results of studies of ancient building materials from France, Italy, China, and Egypt, combined with knowledge obtained from the behavior of modern portland cement to evaluate the potential for stability and durability of such materials in nuclear waste forms.

  19. Durable Tactile Glove for Human or Robot Hand

    NASA Technical Reports Server (NTRS)

    Butzer, Melissa; Diftler, Myron A.; Huber, Eric

    2010-01-01

    A glove containing force sensors has been built as a prototype of tactile sensor arrays to be worn on human hands and anthropomorphic robot hands. The force sensors of this glove are mounted inside, in protective pockets; as a result of this and other design features, the present glove is more durable than earlier models.

  20. Impact of Biodiesel Impurities on the Performance and Durability of DOC, DPF and SCR Technologies

    SciTech Connect

    Williams, A.; McCormick, R.; Luecke, J.; Brezny, R.; Geisselmann, A.; Voss, K.; Hallstrom, K.; Leustek, M.; Parsons, J.; Abi-Akar, H.

    2011-06-01

    It is estimated that operating continuously on a B20 fuel containing the current allowable ASTM specification limits for metal impurities in biodiesel could result in a doubling of ash exposure relative to lube-oil derived ash. The purpose of this study was to determine if a fuel containing metals at the ASTM limits could cause adverse impacts on the performance and durability of diesel emission control systems. An accelerated durability test method was developed to determine the potential impact of these biodiesel impurities. The test program included engine testing with multiple DPF substrate types as well as DOC and SCR catalysts. The results showed no significant degradation in the thermo-mechanical properties of cordierite, aluminum titanate, or silicon carbide DPFs after exposure to 150,000 mile equivalent biodiesel ash and thermal aging. However, exposure of a cordierite DPF to 435,000 mile equivalent aging resulted in a 69% decrease in the thermal shock resistance parameter. It is estimated that the additional ash from 150,000 miles of biodiesel use would also result in a moderate increases in exhaust backpressure for a DPF. A decrease in DOC activity was seen after exposure to 150,000 mile equivalent aging, resulting in higher HC slip and a reduction in NO{sub 2} formation. The metal-zeolite SCR catalyst experienced a slight loss in activity after exposure to 435,000 mile equivalent aging. This catalyst, placed downstream of the DPF, showed a 5% reduction in overall NOx conversion activity over the HDDT test cycle.

  1. 40 CFR 86.1825-01 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... an other regression technique approved in advance by the Administrator. The DF will be calculated to... mileage (e.g., 4000-mile) refueling loss emission level from the regression analysis. The DF and the full...)(1). Calculated DF values of less than zero shall be changed to zero for the purposes of...

  2. 40 CFR 86.1824-07 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  3. 40 CFR 86.1824-07 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1824-07...

  4. 40 CFR 86.1824-07 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  5. 40 CFR 86.1824-07 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  6. 40 CFR 86.1824-07 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  7. 40 CFR 86.1823-08 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1823-08... described as follows: (1) Mileage accumulation must be conducted using the standard road cycle (SRC). The... bench is conducted by following the standard bench cycle (SBC) for the period of time calculated...

  8. 40 CFR 86.1823-01 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... model years 2001, 2002, and 2003 all manufacturers may elect to meet the provisions of paragraph (c)(2... based upon whole-vehicle full-mileage accumulation, whole vehicle accelerated mileage accumulation (e.g...), divided by the stabilized mileage (reference § 86.1831-01(c), e.g., 4000-mile) level (rounded to...

  9. 40 CFR 86.1825-01 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... life. The manufacturer shall use good engineering judgment in determining this process. (a) Service... full useful life. The manufacturer shall use good engineering judgement in developing this method. (2... accumulation programs, all emission control components and systems (including both hardware and software)...

  10. 40 CFR 86.1823-01 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1823-01...-duty trucks, complete heavy-duty vehicles, and heavy-duty vehicles certified under the provisions...

  11. 40 CFR 86.1825-01 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1825-01..., light-duty trucks, and complete heavy-duty vehicles, and heavy-duty vehicles which are certified...

  12. 40 CFR 86.1825-01 - Durability demonstration procedures for refueling emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1825-01..., light-duty trucks, and complete heavy-duty vehicles, and heavy-duty vehicles which are certified...

  13. 40 CFR 86.1823-01 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1823-01...-duty trucks, complete heavy-duty vehicles, and heavy-duty vehicles certified under the provisions...

  14. 40 CFR 86.1824-01 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... available in any state in the United States. Unless otherwise approved by the Administrator, the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  15. 40 CFR 86.1824-08 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... is commercially available in any state in the United States. Unless otherwise approved by the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  16. 40 CFR 86.1824-01 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... available in any state in the United States. Unless otherwise approved by the Administrator, the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  17. 40 CFR 86.1824-01 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... available in any state in the United States. Unless otherwise approved by the Administrator, the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  18. 40 CFR 86.1824-01 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... available in any state in the United States. Unless otherwise approved by the Administrator, the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  19. 40 CFR 86.1824-08 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... is commercially available in any state in the United States. Unless otherwise approved by the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  20. 40 CFR 86.1824-08 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... is commercially available in any state in the United States. Unless otherwise approved by the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  1. 40 CFR 86.1824-08 - Durability demonstration procedures for evaporative emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... is commercially available in any state in the United States. Unless otherwise approved by the... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles §...

  2. 40 CFR 86.1823-08 - Durability demonstration procedures for exhaust emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... vehicles. (2) This data set must consist of randomly procured vehicles from actual customer use. The...) Manufacturers must remove unrepresentative data from the data set using good engineering judgement. The... vehicles included in the data set required in (e)(1)(iii)(A) of this section and the vehicle designs...

  3. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Berggren, M.H.; Jha, M.C.

    1989-10-01

    AMAX Research Development Center (AMAX R D) investigated methods for enhancing the reactivity and durability of zinc ferrite desulfurization sorbents. Zinc ferrite sorbents are intended for use in desulfurization of hot coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. For this program, the reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point and at saturation in a bench-scale, fixed-bed reactor. Durability may be defined as the ability of the sorbent to maintain important physical characteristics such as size, strength, and specific surface area during 10 cycles of sulfidation and oxidation. Two base case sorbents, a spherical pellet and a cylindrical extrude used in related METC-sponsored projects, were used to provide a basis for the aimed enhancement in durability and reactivity. Sorbent performance was judged on the basis of physical properties, single particle kinetic studies based on thermogravimetric (TGA) techniques, and multicycle bench-scale testing of sorbents. A sorbent grading system was utilized to quantify the characteristics of the new sorbents prepared during the program. Significant enhancements in both reactivity and durability were achieved for the spherical pellet shape over the base case formulation. Overall improvements to reactivity and durability were also made to the cylindrical extrude shape. The primary variables which were investigated during the program included iron oxide type, zinc oxide:iron oxide ratio, inorganic binder concentration, organic binder concentration, and induration conditions. The effects of some variables were small or inconclusive. Based on TGA studies and bench-scale tests, induration conditions were found to be very significant.

  4. Multi-factor Effects on the Durability of Recycle Aggregate Concrete

    NASA Astrophysics Data System (ADS)

    Ma, Huan; Cui, Yu-Li; Zhu, Wen-Yu; Xie, Xian-Jie

    2016-05-01

    Recycled Aggregate Concrete (RAC) was prepared with different recycled aggregate replacement ratio, 0, 30%, 70% and 100% respectively. The performances of RAC were examined by the freeze-thaw cycle, carbonization and sulfate attack to assess the durability. Results show that test sequence has different effects on the durability of RAC; the durability is poorer when carbonation experiment was carried out firstly, and then other experiment was carried out again; the durability is better when recycled aggregate replacement ratio is 70%.

  5. 30 CFR 816.73 - Disposal of excess spoil: Durable rock fills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Disposal of excess spoil: Durable rock fills...-SURFACE MINING ACTIVITIES § 816.73 Disposal of excess spoil: Durable rock fills. The regulatory authority may approve the alternative method of disposal of excess durable rock spoil by gravity placement...

  6. 30 CFR 817.73 - Disposal of excess spoil: Durable rock fills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Disposal of excess spoil: Durable rock fills...-UNDERGROUND MINING ACTIVITIES § 817.73 Disposal of excess spoil: Durable rock fills. The regulatory authority may approve the alternative method of disposal of excess durable rock spoil by gravity placement...

  7. Experimental evaluation of the durability of innovative cementitious coatings: photocatalytic activity and colour

    NASA Astrophysics Data System (ADS)

    Alaimo, G.; Enea, D.; Guerrini, G. L.; Bottalico, L.

    2011-11-01

    Today, in a world context characterized by high pollution levels and increasingly limited natural resources, even in the building sector, focusing on environmental issues, through energy saving and a more rational use of these resources, both during construction and management, is fundamental. An important contribution in this direction is given by the knowledge of the durability of products and building components, especially when innovative products are applied and no information are available on the reliability and service life. The research concerns the evaluation of the durability of cement-based photocatalytic coatings ("rasanti" in the Italian diction), containing different types of pigments, used for the external finishing of the buildings envelope and applied in low thicknesses on different supports. These products were prepared using photocatalytic cements by Italcementi (TX ActiveR) The investigated aspects are: the photocatalytic properties, conferring self-cleaning attitude and reduced maintenance to the treated surfaces, and the colorimetric ones, meaning the conservation of colour and giving aesthetic quality to the building envelope. The paper presents some results carried out on TX ActiveR cement-based coatings, performed according to the ISO 15686 methodology, aimed at defining the Reference Service Life, through accelerated ageing tests in climatic chamber and the corresponding monitoring of photocatalytic and colorimetric properties. The photocatalytic tests were carried out according to the UNI 11247-2010, in terms of NOx abatement capability, and the colour measurements were taken on the CIELAB colour space.

  8. Experimental evaluation of the durability of innovative cementitious coatings: photocatalytic activity and colour

    NASA Astrophysics Data System (ADS)

    Alaimo, G.; Enea, D.; Guerrini, G. L.; Bottalico, L.

    2012-04-01

    Today, in a world context characterized by high pollution levels and increasingly limited natural resources, even in the building sector, focusing on environmental issues, through energy saving and a more rational use of these resources, both during construction and management, is fundamental. An important contribution in this direction is given by the knowledge of the durability of products and building components, especially when innovative products are applied and no information are available on the reliability and service life. The research concerns the evaluation of the durability of cement-based photocatalytic coatings ("rasanti" in the Italian diction), containing different types of pigments, used for the external finishing of the buildings envelope and applied in low thicknesses on different supports. These products were prepared using photocatalytic cements by Italcementi (TX ActiveR) The investigated aspects are: the photocatalytic properties, conferring self-cleaning attitude and reduced maintenance to the treated surfaces, and the colorimetric ones, meaning the conservation of colour and giving aesthetic quality to the building envelope. The paper presents some results carried out on TX ActiveR cement-based coatings, performed according to the ISO 15686 methodology, aimed at defining the Reference Service Life, through accelerated ageing tests in climatic chamber and the corresponding monitoring of photocatalytic and colorimetric properties. The photocatalytic tests were carried out according to the UNI 11247-2010, in terms of NOx abatement capability, and the colour measurements were taken on the CIELAB colour space.

  9. Reflectivity, polarization properties, and durability of metallic mirror coatings for the European Solar Telescope

    NASA Astrophysics Data System (ADS)

    Feller, A.; Krishnappa, N.; Pleier, O.; Hirzberger, J.; Jobst, P. J.; Schürmann, M.

    2012-09-01

    In the context of the conceptual design study for the European Solar Telescope (EST) we have investigated different metallic mirror coatings in terms of reflectivity, polarization properties and durability. Samples of the following coating types have been studied: bare aluminum, silver with different dielectric layers for protection and UV enhancement, and an aluminum-silver combination. From 2009 to 2011 we have carried out a long-term durability test under realistic observing conditions at the VTT solar telescope of the Observatorio del Teide (Tenerife, Spain), accompanied by repeated reflectivity measurements in the EST spectral working range (0.3 - 20 μm), and by polarization measurements in the visible range. The test results allow us to find the optimum coatings for the different mirrors in the EST beampath and to eventually assess aging effects and re-coating cycles. The results of the polarization measurements are a valuable input for an EST telescope polarization model, helping to meet the stringent requirements on polarimetric accuracy.

  10. The Influence of Sizings on the Durability of High-Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Allred, Ronald E.; Wesson, Sheldon P.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter, James K.

    2004-01-01

    To increase performance and durability of high-temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide resins. Sizings commercially supplied on most carbon fibers are not compatible with polyimides. In this study, the chemistry of sizings on two high-modulus carbon fibers (M40J and M60J, Toray) was characterized as was the chemistry of PMR-II-50 fluorinated polyimide resin. The carbon fibers were characterized using single filament wetting, scanning electron microscopy, fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopic measurements. The polyimide matrix resins were coated onto glass filaments for characterization by wetting measurements. Surface energy components were obtained by wetting with nondispersive (methylene iodide), acidic (ethylene glycol), and basic (formamide) probes. A continuous desizing system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room-temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the better bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

  11. Dental Procedures.

    PubMed

    Ramponi, Denise R

    2016-01-01

    Dental problems are a common complaint in emergency departments in the United States. There are a wide variety of dental issues addressed in emergency department visits such as dental caries, loose teeth, dental trauma, gingival infections, and dry socket syndrome. Review of the most common dental blocks and dental procedures will allow the practitioner the opportunity to make the patient more comfortable and reduce the amount of analgesia the patient will need upon discharge. Familiarity with the dental equipment, tooth, and mouth anatomy will help prepare the practitioner for to perform these dental procedures. PMID:27482994

  12. Evolutionary model of an anonymous consumer durable market

    NASA Astrophysics Data System (ADS)

    Kaldasch, Joachim

    2011-07-01

    An analytic model is presented that considers the evolution of a market of durable goods. The model suggests that after introduction goods spread always according to a Bass diffusion. However, this phase will be followed by a diffusion process for durable consumer goods governed by a variation-selection-reproduction mechanism and the growth dynamics can be described by a replicator equation. The theory suggests that products play the role of species in biological evolutionary models. It implies that the evolution of man-made products can be arranged into an evolutionary tree. The model suggests that each product can be characterized by its product fitness. The fitness space contains elements of both sites of the market, supply and demand. The unit sales of products with a higher product fitness compared to the mean fitness increase. Durables with a constant fitness advantage replace other goods according to a logistic law. The model predicts in particular that the mean price exhibits an exponential decrease over a long time period for durable goods. The evolutionary diffusion process is directly related to this price decline and is governed by Gompertz equation. Therefore it is denoted as Gompertz diffusion. Describing the aggregate sales as the sum of first, multiple and replacement purchase the product life cycle can be derived. Replacement purchase causes periodic variations of the sales determined by the finite lifetime of the good (Juglar cycles). The model suggests that both, Bass- and Gompertz diffusion may contribute to the product life cycle of a consumer durable. The theory contains the standard equilibrium view of a market as a special case. It depends on the time scale, whether an equilibrium or evolutionary description is more appropriate. The evolutionary framework is used to derive also the size, growth rate and price distribution of manufacturing business units. It predicts that the size distribution of the business units (products) is lognormal

  13. Durability of bactericidal activity in electrolyzed neutral water by storage.

    PubMed

    Nagamatsu, Yuki; Chen, Kerr-Kong; Tajima, Kiyoshi; Kakigawa, Hiroshi; Kozono, Yoshio

    2002-06-01

    Electrolyzed strong and weak acid waters have been widely used for sterilization in clinical dentistry because of their excellent bactericidal activities. Electrolyzed neutral water was recently developed with a new concept of long-term good durability in addition to the excellent bactericidal activity similar to acid waters. The present study, evaluated the storage life of this water compared with the acid waters in terms of the changes in pH, oxidation-reduction potential (ORP), residual chlorine and bactericidal activity under several conditions using Staphylococcus aureus 209P. The strong acid water showed a rapid deterioration of its bactericidal activity. The weak acid and neutral waters exhibited excellent durability. Although all the bacteria were annihilated by the contact with the waters even stored for 40 days in the uncapped bottle, the neutral water was superior in further long-term duration.

  14. Method for improving the durability of ion insertion materials

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Cheong, Hyeonsik M.

    2002-01-01

    The invention provides a method of protecting an ion insertion material from the degradative effects of a liquid or gel-type electrolyte material by disposing a protective, solid ion conducting, electrically insulating, layer between the ion insertion layer and the liquid or gel-type electrolyte material. The invention further provides liquid or gel-type electrochemical cells having improved durability having a pair of electrodes, a pair of ion insertion layers sandwiched between the pair of electrodes, a pair of solid ion conducting layers sandwiched between the ion insertion layers, and a liquid or gel-type electrolyte material disposed between the solid ion conducting layers, where the solid ion conducting layer minimizes or prevents degradation of the faces of the ion insertion materials facing the liquid or gel-type electrolyte material. Electrochemical cells of this invention having increased durability include secondary lithium batteries and electrochromic devices.

  15. High Performance and Durable Low PGM Cathode Catalysts

    SciTech Connect

    Wang, Yong; Liu, Jun; Shao, Yuyan; Cheng, Yingwen; Borup, Rodney L.; Rockward, Tommy; Brosha, Eric Lanich

    2015-08-17

    There is a strong need to decrease the amount of Pt electrocatalyst used in fuel cells and increase its durability for transportation application. Conventional strategies include Pt nanocrystals and Pt alloy with well-controlled structures, durable carbon support, non-carbon support, etc. We have developed the so-called “metal-metal oxide-carbon” triple junction concept to stabilize Pt and protect carbon from corrosion. It also improved the activity of Pt. The good performance was not achieved in fuel cell test mainly because of the transport issue due to the use of 2D graphene. In this project, our main goal is to demonstrate the concept in fuel cell device test using 3D porous graphene as support so that the transport issue could be addressed.

  16. Junction box wiring and connector durability issues in photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Kalejs, Juris

    2014-10-01

    We report here on Photovoltaic (PV) module durability issues associated with junction boxes which are under study in Task 10 of the International PV Quality Assurance Task Force (PVQAT). A number of failure modes are being identified in junction boxes in PV arrays in the field which have less than 5 years outdoor operation. Observed failure modes include melted contacts and plastic walls in the junction boxes, separated external connectors and broken latches. Standard IEC and UL tests for modules are designed to expose early mortality failures due to materials selection and design in the assembled module and their impact on performance and safety. Test standards for individual junction box components, when not part of a PV module, are still in development. We will give an overview of the reported field failures associated with junction boxes, and examine standard development as it may impact on testing for durability of junction box connectors over a 25 year life.

  17. Moisture Durability with Vapor-Permeable Insulating Sheathing

    SciTech Connect

    Lepage, R.; Lstiburek, J.

    2013-09-01

    Exterior sheathing insulation is an effective strategy in increasing the overall R-value of wall assemblies; other benefits include decreasing the effects of thermal bridging and increasing the moisture durability of the built assembly. Vapor-permeable exterior insulation, such as mineral board or expanded polystyrene foam, are one such product that may be used to achieve these benefits. However,uncertainty exists on the effects of inward driven moisture and the interaction of increased sheathing temperatures on the moisture durability of the edifice. To address these concerns, Building Science Corporation (BSC) conducted a series of hygrothermal models for cities representing a range of different climate zones. This report describes the research project, key research questions, and theprocedures utilized to analyse the problems.

  18. Electrical Switchability and Dry-Wash Durability of Conductive Textiles

    NASA Astrophysics Data System (ADS)

    Wu, Bangting; Zhang, Bowu; Wu, Jingxia; Wang, Ziqiang; Ma, Hongjuan; Yu, Ming; Li, Linfan; Li, Jingye

    2015-06-01

    There is growing interest in the area of conductive textiles in the scientific and industrial community. Herein, we successfully prepared a conductive textile via covalently grafting polyaniline (PANI) onto cotton by a multi-step treatment process. The conductivity of the resultant fabric could be tuned by immersing in water having different pH values. The conductive and insulating properties of the textile could be conveniently switched by alternately immersing in acidic and alkaline bath solutions. Most importantly, the resultant conductive fabrics were able to withstand 40 simulated dry-wash cycles, with almost no decay in the electrical conductivity, indicating their excellent dry-wash durability. The present strategy for fabricating conductive fabrics with excellent switchability of electrical properties and dry-wash durability is expected to provide inspiration for the production of multifunctional conductive textiles for use in hash or sensitive conditions.

  19. Durability of Polymeric Coatings: Cyclic Loading and Free Volumes

    NASA Astrophysics Data System (ADS)

    Chen, Hongmin; Peng, Qinghua; Wu, Yichu; Li, Ying; Zhang, Junjie; Sandreczki, T. C.; Zhang, Renwu; Jean, Y. C.; Richardson, J. R.

    2002-03-01

    The mechanical durability of seven commercially polymeric coatings is investigated using slow positron beam techniques to monitor changes in sub nanometer defects during the cyclic loading process. Doppler broadened energy spectra and positron annihilation lifetime measurements were performed as a function of the slow positron energy at different periods of cycling loading. The positron annihilation dada show that both S-defect parameter and ortho-positronium intensity decrease as the loading cycles increase. The results indicate a loss of free volumes due to mechanical loading and cycling. A direct correlation between the loss of free-volume parameter and of loading cycle is observed. This is interpreted as that durability of polymeric coatings is controlled by the atomic level defects. It is shown that the slow positron beam is very successful probe in detecting the very early stages of coating degradation due to mechanical processes. Supported by NSF-CMS-9812717

  20. Electrical Switchability and Dry-Wash Durability of Conductive Textiles

    PubMed Central

    Wu, Bangting; Zhang, Bowu; Wu, Jingxia; Wang, Ziqiang; Ma, Hongjuan; Yu, Ming; Li, Linfan; Li, Jingye

    2015-01-01

    There is growing interest in the area of conductive textiles in the scientific and industrial community. Herein, we successfully prepared a conductive textile via covalently grafting polyaniline (PANI) onto cotton by a multi-step treatment process. The conductivity of the resultant fabric could be tuned by immersing in water having different pH values. The conductive and insulating properties of the textile could be conveniently switched by alternately immersing in acidic and alkaline bath solutions. Most importantly, the resultant conductive fabrics were able to withstand 40 simulated dry-wash cycles, with almost no decay in the electrical conductivity, indicating their excellent dry-wash durability. The present strategy for fabricating conductive fabrics with excellent switchability of electrical properties and dry-wash durability is expected to provide inspiration for the production of multifunctional conductive textiles for use in hash or sensitive conditions. PMID:26066704

  1. Durability Challenges for Next Generation of Gas Turbine Engine Materials

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    2012-01-01

    Aggressive fuel burn and carbon dioxide emission reduction goals for future gas turbine engines will require higher overall pressure ratio, and a significant increase in turbine inlet temperature. These goals can be achieved by increasing temperature capability of turbine engine hot section materials and decreasing weight of fan section of the engine. NASA is currently developing several advanced hot section materials for increasing temperature capability of future gas turbine engines. The materials of interest include ceramic matrix composites with 1482 - 1648 C temperature capability, advanced disk alloys with 815 C capability, and low conductivity thermal barrier coatings with erosion resistance. The presentation will provide an overview of durability challenges with emphasis on the environmental factors affecting durability for the next generation of gas turbine engine materials. The environmental factors include gaseous atmosphere in gas turbine engines, molten salt and glass deposits from airborne contaminants, impact from foreign object damage, and erosion from ingestion of small particles.

  2. Mechanical durability of superhydrophobic and oleophobic copper meshes

    NASA Astrophysics Data System (ADS)

    Yin, Linting; Yang, Jin; Tang, Yongcai; Chen, Lin; Liu, Can; Tang, Hua; Li, Changsheng

    2014-10-01

    We developed a simple and inexpensive method to prepare the superhydrophobic and oleophobic copper meshes with rough structures fabrication and chemical modification. The achieved surfaces displayed liquid-repellent toward water and several organic liquids (such as hexadecane), which possessed much lower surface tension than that of water. Liquid repellency of the fabricated superhydrophobic copper mesh was demonstrated by visible experiment results and contact angle measurements. Even if the superhydrophobic copper mesh was rolled up, it still kept the superhydrophobicity. The mechanical durability was investigated by finger touch and mechanical abrasion tests. The results indicated that the copper mesh can maintain its superhydrophobicity against an abrasion length of 300 cm under a high pressure (77.2 kPa). The superhydrophobicity and oleophobicity, combined with mechanical durability, would promote the superhydrophobic surface to practical application in industry in the future.

  3. Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

    SciTech Connect

    Jha, M.C.; Berggren, M.H.

    1987-10-27

    AMAX Research Development Center (AMAX R D) has been investigating methods for improving the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hog coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. The reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point in a bench-scale fixed-bed reactor. The durability may be defined as the ability of the sorbent to maintain its reactivity and other important physical characteristics such as size, strength, and specific surface area during 10 cycles of sulfidation and regeneration. Two base case sorbents, spherical pellets and cylindrical extrudes used in related METC sponsored projects, are being used to provide a basis for the comparison of physical characteristics and chemical reactivity.

  4. Durable zinc ferrite sorbent pellets for hot coal gas desulfurization

    DOEpatents

    Jha, Mahesh C.; Blandon, Antonio E.; Hepworth, Malcolm T.

    1988-01-01

    Durable, porous sulfur sorbents useful in removing hydrogen sulfide from hot coal gas are prepared by water pelletizing a mixture of fine zinc oxide and fine iron oxide with inorganic and organic binders and small amounts of activators such as sodium carbonate and molybdenite; the pellets are dried and then indurated at a high temperature, e.g., 1800.degree. C., for a time sufficient to produce crush-resistant pellets.

  5. Advances in Understanding Durability of the Building Envelope: ORNL Research

    SciTech Connect

    Kehrer, Manfred; Desjarlais, Andre Omer

    2013-01-01

    Moisture, and its accompanying outriders things like mold, corrosion, freeze damage, and decay present powerful threats to the durability and long-term performance of a building envelope. Miscalculating the impact of environmental factors like rain, solar radiation, temperature, humidity, and indoor sources of moisture can cause significant damage to many types of building envelope components and materials, and also can lead to unhealthy indoor living environments.

  6. Use of recycled fine aggregate in concretes with durable requirements.

    PubMed

    Zega, Claudio Javier; Di Maio, Angel Antonio

    2011-11-01

    The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. PMID:21775123

  7. Use of recycled fine aggregate in concretes with durable requirements.

    PubMed

    Zega, Claudio Javier; Di Maio, Angel Antonio

    2011-11-01

    The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete.

  8. Durability of organobentonite-amended liner for decelerating chloroform transport.

    PubMed

    He, Shichong; Zhu, Lizhong

    2016-04-01

    Chloroform is added to landfill for suppressing methane generation, which however may transport through landfill liners and lead to contamination of groundwater. To decelerate chloroform transport, the enhanced sorption ability of clay liners following organobentonite addition was tested. In this study, we used batch sorption to evaluate sorption capacity of chloroform to organobentonite, followed by column tests and model simulations for assessing durability of different liners. Results show that adding 10% CTMAB-bentonite (organobentonite synthesized using cetyltrimethylammonium bromide) increased the duration of a bentonite liner by 88.5%. CTMAB-bentonite consistently showed the highest sorption capacity (Qm) among six typical organobentonites under various environmental conditions. The removal rate of chloroform by CTMAB-bentonite was 3.6-23 times higher than that by natural soils. According to the results derived by model simulation, a 70-cm 10% CTMAB-bentonite liner exhibited much better durability than a 100-cm compact clay liner (CCL) and natural bentonite liner evidenced by the delayed and lower peak of eluent concentration. A minimum thickness of 65.8 cm of the 10% CTMAB-bentonite liner could completely sorb the chloroform in a 100-m-high landfill. The 10% CTMAB-bentonite liner exhibiting much better durability has the promise for reducing environmental risk of chloroform in landfill.

  9. Study of the durability of demolition aggregates on pavements

    NASA Astrophysics Data System (ADS)

    Bachir, Melbouci; Fazia, Boudjemia

    2009-06-01

    This work is an experimental contribution to the study of durability of various materials coming from the demolition of buildings for their use in the flexible infrastructures of pavements. However, these pavements undergo traffic loading which causes, in the long time permanent deformations and settlements thus generating significant degradations of materials. Various recent works aim at characterizing these materials. This work falls under this scope and gives an approach of the mechanical behavior and the response of these last to repetitive loadings. After identification of materials and the determination of the characteristics of hardness and durability, we studied their mechanical behavior with cyclic shearing on these three materials (aggregates of concrete, brick and concrete block). These tests enabled us to analyze the mechanisms which occur through the various parameters related to loading (the amplitude and the repetition of loading, the parameters related to materials (the water content, the density and the grain size distribution). The study of the durability of these materials consists on quantifying the degradation rate of the grains after the various tests and the grain size distribution which governs the amplitude of crushing.

  10. Durability evaluation of biopolymer coating on titanium alloy substrate.

    PubMed

    Ryan Stanfield, J; Bamberg, Stacy

    2014-07-01

    For this study, a commercially available phosphorylcholine (PC) polymer was applied to Ti6Al4V ELI. A multivariate approach to design a statistically significant array of experiments was employed to evaluate and estimate optimization of PC-immobilization process factors. The seven process factors analyzed were (1) power level for RFGD plasma treatment, (2) duration of plasma treatment, (3) concentration of PC solution used to coat samples, (4) rate at which samples were dipped in/out of the solution, (5) temperature for curing, (6) relative humidity level during curing, and (7) duration of curing. Imaging and analysis of the coating were done via fluorescence microscopy (FM), confirming the uniform coverage of PC polymer on titanium substrate. The process factors were evaluated by three measured responses: initial thickness, coating durability and degree of cross-linked coating, which were assessed by FM, a spray test and extraction in IPA, respectively. Variations in PC solution concentration showed no impact on fouling resistance of the resultant coating. It was hypothesized that the PC-application process factors could be optimized to yield favorable outcomes in durability and degree of cross-linked coating responses. The resulting statistical model indicates that PC solution concentration, dip rate, and cure temperature are the three greatest singular effects on both durability and degree of cross-linking. In addition, plasma treatment of the substrate with O2 was effective in enhancing the degree of cross-linking of the polymer surface.

  11. Multimodal management of atrophic acne scarring in the aging face.

    PubMed

    O'Daniel, T Gerald

    2011-12-01

    Atrophic facial acne scarring is a widely prevalent condition that can have a negative impact on a patient's quality of life. The appearance of these scars is often worsened by the normal effects of aging. A number of options are available for the treatment of acne scarring, including chemical peeling, dermabrasion, ablative or nonablative laser resurfacing, dermal fillers, and surgical techniques such as subcision or punch excision. Depending on the type and extent of scarring, a multimodal approach is generally necessary to provide satisfactory results. Resurfacing techniques correct surface irregularities, long-lasting dermal fillers address the volume loss resulting from acne, and sub-superficial musculoaponeurotic system (SMAS) face-lift procedures counter the soft tissue laxity and ptosis associated with aging. This article briefly reviews the evolution of individual approaches to treating atrophic acne scarring, followed by case examples illustrating results that can be achieved using a multimodal approach. Representative cases from patients in their 30s, 40s, and 50s are presented. In the author's clinical practice, multimodal approaches incorporating fractionated laser, injectable poly-L: -lactic acid, and sub-SMAS face-lift procedures have achieved optimal aesthetic outcomes, high patient satisfaction, and durability of aesthetic effect over time. PMID:21491169

  12. Bio-inspired durable, superhydrophobic magnetic particles for oil/water separation.

    PubMed

    Zhang, Liang; Li, Lili; Dang, Zhi-Min

    2016-02-01

    In the present study, superhydrophobic and superoleophilic microparticles with magnetic property were fabricated by combining the oxidation and self-polymerization of dopamine and formation of Fe3O4 nanoparticles on the surface of the polydopamine (PDA) particles, followed by modification with low surface energy material. The modified PDA/Fe3O4 particles showed high water repellency with contact angle (CA) measured at 153.7±1.6° and high oil affinity. The superhydrophobic microparticles preserved high water CA after aging test, showing excellent durability. The microparticles were employed to effectively remove oil from water in different routes. Superhydrophobic sponge was prepared by modifying with the achieved microparticles. The sponge exhibited high absorption capability of oil, with weight gains ranging from 1348% to 7268%. The results suggest this work might provide a promising candidate for oily pollutants/water separation and transportation. PMID:26550784

  13. Impact of Biodiesel Impurities on the Performance and Durability of DOC, DPF and SCR Technologies: Preprint

    SciTech Connect

    Williams, A.; McCormick, R.; Luecke, J.; Brezny, R.; Geisselmann, A.; Voss, K.; Hallstrom, K.; Leustek, M.; Parsons, J.; Abi-Akar, H.

    2011-04-01

    An accelerated durability test method determined the potential impact of biodiesel ash impurities, including engine testing with multiple diesel particulate filter substrate types, as well as diesel oxidation catalyst and selective catalyst reduction catalysts. The results showed no significant degradation in the thermo-mechanical properties of a DPF after exposure to 150,000-mile equivalent biodiesel ash and thermal aging. However, exposure to 435,000-mile equivalent aging resulted in a 69% decrease in thermal shock resistance. A decrease in DOC activity was seen after exposure to 150,000-mile equivalent aging, resulting in higher hydrocarbon slip and a reduction in NO2 formation. The SCR catalyst experienced a slight loss in activity after exposure to 435,000-mile equivalent aging. The SCR catalyst, placed downstream of the DPF and exposed to B20 exhaust suffered a 5% reduction in overall NOx conversion activity over the HDDT test cycle. It is estimated that the additional ash from 150,000 miles of biodiesel use would also result in a moderate increases in exhaust backpressure for a DPF. The results of this study suggest that long-term operation with B20 at the current specification limits for alkali and alkaline earth metal impurities will adversely impact the performance of DOC, DPF and SCR systems.

  14. Upper Airway Stimulation for Obstructive Sleep Apnea: Durability of the Treatment Effect at 18 Months

    PubMed Central

    Strollo, Patrick J.; Gillespie, M. Boyd; Soose, Ryan J.; Maurer, Joachim T.; de Vries, Nico; Cornelius, Jason; Hanson, Ronald D.; Padhya, Tapan A.; Steward, David L.; Woodson, B. Tucker; Verbraecken, Johan; Vanderveken, Olivier M.; Goetting, Mark G.; Feldman, Neil; Chabolle, Frédéric; Badr, M. Safwan; Randerath, Winfried; Strohl, Kingman P.

    2015-01-01

    Objective: To determine the stability of improvement in polysomnographic measures of sleep disordered breathing, patient reported outcomes, the durability of hypoglossal nerve recruitment and safety at 18 months in the Stimulation Treatment for Apnea Reduction (STAR) trial participants. Design: Prospective multicenter single group trial with participants serving as their own controls. Setting: Twenty-two community and academic sleep medicine and otolaryngology practices. Measurements: Primary outcome measures were the apnea-hypopnea index (AHI) and the 4% oxygen desaturation index (ODI). Secondary outcome measures were the Epworth Sleepiness Scale (ESS), the Functional Outcomes of Sleep Questionnaire (FOSQ), and oxygen saturation percent time < 90% during sleep. Stimulation level for each participant was collected at three predefined thresholds during awake testing. Procedure- and/or device-related adverse events were reviewed and coded by the Clinical Events Committee Results: The median AHI was reduced by 67.4% from the baseline of 29.3 to 9.7/h at 18 mo. The median ODI was reduced by 67.5% from 25.4 to 8.6/h at 18 mo. The FOSQ and ESS improved significantly at 18 mo compared to baseline values. The functional threshold was unchanged from baseline at 18 mo. Two participants experienced a serious device-related adverse event requiring neurostimulator repositioning and fixation. No tongue weakness reported at 18 mo. Conclusion: Upper airway stimulation via the hypoglossal nerve maintained a durable effect of improving airway stability during sleep and improved patient reported outcomes (Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire) without an increase of the stimulation thresholds or tongue injury at 18 mo of follow-up. Citation: Strollo PJ, Gillespie MB, Soose RJ, Maurer JT, de Vries N, Cornelius J, Hanson RD, Padhya TA, Steward DL, Woodson BT, Verbraecken J, Vanderveken OM, Goetting MG, Feldman N, Chabolle F, Badr MS, Randerath W

  15. Durability of polyimide adhesives and their bonded joints for high-temperature applications

    NASA Astrophysics Data System (ADS)

    Parvatareddy, Hari

    The objective of this study was to evaluate and develop an understanding of durability of an adhesive bonded system, for application in a future high speed civil transport (HSCT) aircraft structure. The system under study was comprised of Ti-6Al-4V metal adherends and a thermosetting polyimide adhesive, designated as FM-5, supplied by Cytec Engineered Materials, Inc. An approach based on fracture mechanics was employed to assess Ti-6Al-4V/FM-5 bond durability. Initially, wedge tests were utilized to find a durable surface pretreatment for the titanium adherends. Based on an extensive screening study, chromic acid anodization (CAA) was chosen as the standard pretreatment for this research project. Double cantilever beam specimens (DCB) were then made and aged at 150sp°C, 177sp°C, and 204sp°C in three different environments; ambient atmospheric air (14.7 psia), and reduced air pressures of 2 psia (13.8 KPa) and 0.2 psia (1.38 KPa). Joints were aged for up to 18 months (including several intermediate aging times) in the above environments. The strain energy release rate (G) of the adhesive joints was monitored as a function of exposure time in the different environments. A 40% drop in fracture toughness was noted over the 18 month period, with the greatest degradation observed in samples aged at 204sp°C in ambient atmospheric air pressure. The loss in adhesive bond performance with time was attributable to a combination of physical and chemical aging phenomena in the FM-5 resin, and possible degradation of the metal-adhesive interface(s). Several mechanical and material tests, performed on the bonded joints and neat FM-5 resin specimens, confirmed the above statement. It was also noted that physical aging could be "erased" by thermal rejuvenation, partially restoring the toughness of the FM-5 adhesive material. The FM-5 adhesive material displayed good chemical resistance towards organic solvents and other aircraft fluids such as jet fuel and hydraulic fluid. The

  16. Durability of Low Platinum Fuel Cells Operating at High Power Density

    SciTech Connect

    Polevaya, Olga; Blanchet, Scott; Ahluwalia, Rajesh; Borup, Rod; Mukundan, Rangachary

    2014-03-19

    Understanding and improving the durability of cost-competitive fuel cell stacks is imperative to successful deployment of the technology. Stacks will need to operate well beyond today’s state-of-the-art rated power density with very low platinum loading in order to achieve the cost targets set forth by DOE ($15/kW) and ultimately be competitive with incumbent technologies. An accelerated cost-reduction path presented by Nuvera focused on substantially increasing power density to address non-PGM material costs as well as platinum. The study developed a practical understanding of the degradation mechanisms impacting durability of fuel cells with low platinum loading (≤0.2mg/cm2) operating at high power density (≥1.0W/cm2) and worked out approaches for improving the durability of low-loaded, high-power stack designs. Of specific interest is the impact of combining low platinum loading with high power density operation, as this offers the best chance of achieving long-term cost targets. A design-of-experiments approach was utilized to reveal and quantify the sensitivity of durability-critical material properties to high current density at two levels of platinum loading (the more conventional 0.45 mgPt.cm–1 and the much lower 0.2 mgPt.cm–2) across several cell architectures. We studied the relevance of selected component accelerated stress tests (AST) to fuel cell operation in power producing mode. New stress tests (NST) were designed to investigate the sensitivity to the addition of electrical current on the ASTs, along with combined humidity and load cycles and, eventually, relate to the combined city/highway drive cycle. Changes in the cathode electrochemical surface area (ECSA) and average oxygen partial pressure on the catalyst layer with aging under AST and NST protocols were compared based on the number of completed cycles. Studies showed elevated sensitivity of Pt growth to the potential limits and the initial particle size distribution. The ECSA loss

  17. Predictive Nomogram for the Durability of Pain Relief From Gamma Knife Radiation Surgery in the Treatment of Trigeminal Neuralgia

    SciTech Connect

    Lucas, John T.; Nida, Adrian M.; Isom, Scott; Marshall, Kopriva; Bourland, John D.; Laxton, Adrian W.; Tatter, Stephen B.; Chan, Michael D.

    2014-05-01

    Purpose: To determine factors associated with the durability of stereotactic radiation surgery (SRS) for treatment of trigeminal neuralgia (TN). Methods and Materials: Between 1999 and 2008, 446 of 777 patients with TN underwent SRS and had evaluable follow-up in our electronic medical records and phone interview records. The median follow-up was 21.2 months. The Barrow Neurologic Institute (BNI) pain scale was used to determine pre- and post-SRS pain. Dose-volume anatomical measurements, Burchiel pain subtype, pain quality, prior procedures, and medication usage were included in this retrospective cohort to identify factors impacting the time to BNI 4-5 pain relapse by using Cox proportional hazard regression. An internet-based nomogram was constructed based on predictive factors of durable relief pre- and posttreatment at 6-month intervals. Results: Rates of freedom from BNI 4-5 failure at 1, 3, and 5 years were 84.5%, 70.4%, and 46.9%, respectively. Pain relief was BNI 1-3 at 1, 3, and 5 years in 86.1%, 74.3%, and 51.3% of type 1 patients; 79.3%, 46.2%, and 29.3% of type 2 patients; and 62.7%, 50.2%, and 25% of atypical facial pain patients. BNI type 1 pain score was achieved at 1, 3, and 5 years in 62.9%, 43.5%, and 22.0% of patients with type 1 pain and in 47.5%, 25.2%, and 9.2% of type 2 patients, respectively. Only 13% of patients with atypical facial pain achieved BNI 1 response; 42% of patients developed post-Gamma Knife radiation surgery (GKRS) trigeminal dysfunction. Multivariate analysis revealed that post-SRS numbness (hazard ratio [HR], 0.47; P<.0001), type 1 (vs type 2) TN (HR, 0.6; P=.02), and improved post-SRS BNI score at 6 months (HR, 0.009; P<.0001) were predictive of a durable pain response. Conclusions: The durability of SRS for TN depends on the presenting Burchiel pain type, the post-SRS BNI score, and the presence of post-SRS facial numbness. The durability of pain relief can be estimated pre- and posttreatment by using our

  18. Engine rotor health monitoring: an experimental approach to fault detection and durability assessment

    NASA Astrophysics Data System (ADS)

    Abdul-Aziz, Ali; Woike, Mark R.; Clem, Michelle; Baaklini, George

    2015-03-01

    Efforts to update and improve turbine engine components in meeting flights safety and durability requirements are commitments that engine manufacturers try to continuously fulfill. Most of their concerns and developments energies focus on the rotating components as rotor disks. These components typically undergo rigorous operating conditions and are subject to high centrifugal loadings which subject them to various failure mechanisms. Thus, developing highly advanced health monitoring technology to screen their efficacy and performance is very essential to their prolonged service life and operational success. Nondestructive evaluation techniques are among the many screening methods that presently are being used to pre-detect hidden flaws and mini cracks prior to any appalling events occurrence. Most of these methods or procedures are confined to evaluating material's discontinuities and other defects that have mature to a point where failure is eminent. Hence, development of more robust techniques to pre-predict faults prior to any catastrophic events in these components is highly vital. This paper is focused on presenting research activities covering the ongoing research efforts at NASA Glenn Research Center (GRC) rotor dynamics laboratory in support of developing a fault detection system for key critical turbine engine components. Data obtained from spin test experiments of a rotor disk that relates to investigating behavior of blade tip clearance, tip timing and shaft displacement based on measured data acquired from sensor devices such as eddy current, capacitive and microwave are presented. Additional results linking test data with finite element modeling to characterize the structural durability of a cracked rotor as it relays to the experimental tests and findings is also presented. An obvious difference in the vibration response is shown between the notched and the baseline no notch rotor disk indicating the presence of some type of irregularity.

  19. Durability testing at one atmosphere of advanced catalysts and catalyst supports for automotive gas turbine engine combustors, part 1

    NASA Technical Reports Server (NTRS)

    Heck, R. M.; Chang, M.; Hess, H.; Carrubba, R.

    1977-01-01

    The durability of catalysts and catalyst supports in a combustion environment was experimentally demonstrated. A test of 1000 hours duration was completed with two catalysts, using diesel fuel and operating at catalytically supported thermal combustion conditions. The performance of the catalysts was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. The test catalysts proved to be capable of low emissions operation after 1000 hours diesel aging, with no apparent physical degradation of the catalyst support.

  20. Advances in Thin Film Thermocouple Durability Under High Temperature and Pressure Testing Conditions

    NASA Technical Reports Server (NTRS)

    Martin, Lisa C.; Fralick, Gustave C.; Taylor, Keith F.

    1999-01-01

    Thin film thermocouples for measuring material surface temperature have been previously demonstrated on several material systems and in various hostile test environments. A well-developed thin film fabrication procedure utilizing shadow masking for patterning the sensors elements had produced thin films with sufficient durability for applications in high temperature and pressure environments that exist in air-breathing and hydrogen-fueled burner rig and engine test facilities. However, while shadow masking had been a reliable method for specimens with flat and gently curved surfaces, it had not been consistently reliable for use on test components with sharp contours. This work reports on the feasibility of utilizing photolithography processing for patterning thin film thermocouples. Because this patterning process required changes in the thin film deposition process from that developed for shadow masking, the effect of these changes on thin film adherence during burner rig testing was evaluated. In addition to the results of changing the patterning method, the effects on thin film adherence of other processes used in the thin film fabrication procedure is also presented.

  1. Pial synangiosis in patients with moyamoya younger than 2 years of age.

    PubMed

    Jackson, Eric M; Lin, Ning; Manjila, Sunil; Scott, R Michael; Smith, Edward R

    2014-04-01

    Object Patients with moyamoya who are younger than 2 years of age represent a therapeutic challenge because of their frequent neurological instability and concomitant anesthetic risks. The authors report their experience with pial synangiosis revascularization in this population. Methods The authors reviewed the clinical and radiographic records of all patients with moyamoya in a consecutive series of patients under 2 years of age, who underwent cerebral revascularization surgery using pial synangiosis at a single institution. Results During a 12-year period (1994-2005), 34 procedures (bilateral in 15 patients, unilateral in 4) were performed in 19 patients younger than 2 years (out of a total of 456 procedures in 240 patients). Eighteen of these patients presented with either stroke or transient ischemic attack. The average age of the 19 patients at first surgery was 1.4 years (range 6 months-1.9 years). Unanticipated staged operations occurred in 3 patients, due to persistent electroencephalographic changes during the initial surgery in 2 cases and due to brain swelling during the procedure requiring ventriculostomy in the other. There were 2 perioperative strokes; both patients had postoperative seizures but made clinical recoveries. The average follow-up was 7 years (range 1-14 years). Long term, at follow-up, 13 patients (68%) were clinically independent for their age, with 8 (42%) having no significant deficit. Late complications included subdural hygroma evacuation (1), additional revascularization procedures performed years later for frontal lobe ischemia (2), late infarction (1), and asymptomatic ischemic change on routine follow-up MRI studies (1). All patients who had both pre- and postoperative angiography demonstrated progression of disease. Conclusions Despite the challenges inherent to this population, the majority of children with moyamoya under the age of 2 years have a good long-term prognosis. The data from this study support the use of pial

  2. Advanced Stirling Convertor Durability Testing: Plans and Interim Results

    NASA Technical Reports Server (NTRS)

    Meer, David W.; Oriti, Salvatore M.

    2012-01-01

    The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. In support of this program, GRC has been involved in testing Stirling convertors, including the Advanced Stirling Convertor (ASC), for use in the ASRG. This testing includes electromagnetic interference/compatibility (EMI/EMC), structural dynamics, advanced materials, organics, and unattended extended operation. The purpose of the durability tests is to experimentally demonstrate the margins in the ASC design. Due to the high value of the hardware, previous ASC tests focused on establishing baseline performance of the convertors within the nominal operating conditions. The durability tests present the first planned extension of the operating conditions into regions beyond those intended to meet the product spec, where the possibility exists of lateral contact, overstroke, or over-temperature events. These tests are not intended to cause damage that would shorten the life of the convertors, so they can transition into extended operation at the conclusion of the tests. This paper describes the four tests included in the durability test sequence: 1) start/stop cycling, 2) exposure to constant acceleration in the lateral and axial directions, 3) random vibration at increased piston amplitude to induce contact events, and 4) overstroke testing to simulate potential failures during processing or during the mission life where contact events could occur. The paper also summarizes the analysis and simulation used to predict the results of each of these tests.

  3. Advanced Stirling Convertor Durability Testing: Plans and Interim Results

    NASA Technical Reports Server (NTRS)

    Meer, Dave; Oriti, Sal

    2012-01-01

    The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. In support of this program, NASA?s Glenn Research Center (GRC) has been involved in testing Stirling convertors, including the Advanced Stirling Convertor (ASC), for use in the ASRG. This testing includes electromagnetic interference/compatibility (EMI/EMC), structural dynamics, advanced materials, organics, and unattended extended operation. The purpose of the durability tests is to experimentally demonstrate the margins in the ASC design. Due to the high value of the hardware, previous ASC tests focused on establishing baseline performance of the convertors within the nominal operating conditions. The durability tests present the first planned extension of the operating conditions into regions beyond those intended to meet the product spec, where the possibility exists of lateral contact, overstroke, or over-temperature events. These tests are not intended to cause damage that would shorten the life of the convertors, so they can transition into extended operation at the conclusion of the tests. This paper describes the four tests included in the durability test sequence: 1) start/stop cycling, 2) exposure to constant acceleration in the lateral and axial directions, 3) random vibration at increased piston amplitude to induce contact events, and 4) overstroke testing to simulate potential failures during processing or during the mission life where contact events could occur. The paper also summarizes the analysis and simulation used to predict the results of each of these tests.

  4. Formation and durability of hydrated layers for several oxide glasses

    SciTech Connect

    Nishii, Junji; Akai, Tomoko; Yamashita, Masaru; Yamanaka, Hiroshi; Wakabayashi, Hajimu

    1995-12-31

    Formations and durabilities of hydrated layers were compared between a soda-aluminosilicate (NAS), a soda-lime-aluminosilicate (NCAS) and a soda-lime-alumino-borosilicate (NCABS) glasses. The first step of the study was to prepare the optically transparent hydrated layers on the surface of specimens by an autoclave (400 C, 20 kgf/cm{sup 2}) treatment. Distributions of OH groups in hydrated layers were analyzed by an etch sectioning and FTIR measurement. The rates of hydration of the glasses were in the order NAS {much_gt} NCAS > NCABS. The hydration of the NCABS glass, which is a modified nuclear waste glass, required the treatment longer than those of the NAS and NCAS glasses. In the second step, the authors investigated the durabilities of hydrated layers by immersing the specimens into a distilled water at 100 C. The dissolutions of hydrated layers were confirmed for each glass. The dissolution rates of hydrated layers were in the order NCAS > NCABS {much_gt} NAS. It has become apparent by an XPS analysis that the highest durability of the hydrated NAS glass was due to the formation of a sodium free Al{sub 2}O{sub 3}-SiO{sub 2} layer on the surface. The hydrated layer of the NCAS glass, while the sodium ions were almost leached out during immersion, dissolved to water most quickly than those of other glasses. In the hydrated layer of the NCABS glass, a half amount of sodium and boron ions remained and inhibited the dissolution of hydrated layer.

  5. Therma1 Conductivity and Durability of Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2003-01-01

    Thermal barrier coatings (TBCs) will play a crucial role in advanced gas turbine engines because of their ability to further increase engine operating temperature and reduce cooling, thus helping to achieve engine emission and efficiency goals. Future TBCs must be designed with increased phase stability, lower thermal conductivity, and improved sintering and thermal stress resistance in order to effectively protect engine hot-section components. Advanced low conductivity TBCs are being developed at NASA by incorporating multi-component oxide dopants into zirconia-yttria or hafnia-yttria to promote the formation of thermodynamically stable defect clusters within the coating structures. This presentation will primarily focus on thermal conductivity and durability of the novel defect cluster thermal barrier coatings for turbine airfoil and combustor applications, determined by a unique CO2 laser heat-flux approach. The laser heat-flux testing approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity under simulated engine temperature and thermal gradient conditions. The conductivity increase due to coating sintering (and/or phase change) and the conductivity decrease due to coating delamination have been determined under steady-state, cyclic, uniform or non-uniform heat-flux conditions. The coating radiation flux resistance has been evaluated by varying coating thermal gradients, and also by using a laser-heated radiative-flux source. Advanced multi-component TBC systems have been shown to have significantly reduced thermal conductivity and improved high temperature stability due to the nano-sized, low mobility defect clusters associated with the paired rare earth dopant additions. The effect of oxide defect cluster dopants on coating thermal conductivity, thermal stability and furnace cyclic durability will also be discussed. The current low conductivity TBC systems have demonstrated long-term cyclic durability at very high

  6. Durability testing of antireflection coatings for solar applications

    SciTech Connect

    Jorgensen, G.; Brunold, S.; Koehl, M.; Nostell, P.; Roos, A.; Oversloot, H.

    2000-01-05

    Antireflection (AR) coatings can be incorporated into highly transmitting glazings that, depending on their cost, performance, and durability of optical properties, can be economically viable in solar collectors, agricultural greenhouses, and PV systems. A number of AR-coated glazings have been prepared under the auspices of the International Energy Agency (IEA) Working Group on Durability of Materials for Solar Thermal Collectors. The AR coatings are of two types, including (1) various sol-gels applied to glass and (2) an embossed treatment of sheet acrylic. Typically, for unweathered glazings, a 4%--5% increase in solar-weighted transmittance has been achieved. For AR-coated glass, reflectance values as low as 0.5%--0.7% at selected wavelengths (680--720 nm) were obtained. To determine the durability of the hemispherical transmittance, several collaborating countries are testing these materials both outdoors and in accelerated weathering chambers. All materials exposed outdoors are affixed to mini-collector boxes to simulate flat-plate collector conditions. Results for candidate AR coatings weathered at geographically disperse outdoor test sites exhibit changes in spectral transmittance primarily in the high visible range (600--700 nm). Accelerated testing at measured levels of simulated solar irradiance and at different constant levels of temperature and relative humidity have been performed in different countries. Parallel testing with different levels of laboratory-controlled relevant stress factors permits the time-dependent performance of these materials to be compared with measured results from in-service outdoor exposure conditions. Coating adhesion and performance loss resulting from dirt and dust retention are also discussed.

  7. Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Modules: Preprint

    SciTech Connect

    Miller, D. C.; Gedvilas, L. M.; To, B.; Kennedy, C. E.; Kurtz, S. R.

    2010-08-01

    Concentrating photovoltaic (CPV) technology has recently gained interest based on their expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems use Fresnel lenses made of poly(methyl methacrylate)(PMMA) to obtain a high optical flux density. The optical and mechanical durability of such components, however, are not well established relative to the desired service life of 30 years. Specific reliability issues may include: reduced optical transmittance, discoloration, hazing, surface erosion, embrittlement, crack growth, physical aging, shape setting (warpage), and soiling. The initial results for contemporary lens- and material-specimens aged cumulatively to 6 months are presented. The study here uses an environmental chamber equipped with a xenon-arc lamp to age specimens at least 8x the nominal field rate. A broad range in the affected characteristics (including optical transmittance, yellowness index, mass loss, and contact angle) has been observed to date, depending on the formulation of PMMA used. The most affected specimens are further examined in terms of their visual appearance, surface roughness (examined via atomic force microscopy), and molecular structure (via Fourier transform infrared spectroscopy).

  8. Procedural knowledge

    SciTech Connect

    Georgeff, M.P.; Lansky, A.L.

    1986-10-01

    Much of commonsense knowledge about the real world is in the form of procedures or sequences of actions for achieving particular goals. In this paper, a formalism is presented for representing such knowledge using the notion of process. A declarative semantics for the representation is given, which allows a user to state facts about the effects of doing things in the problem domain of interest. An operational semantics is also provided, which shows how this knowledge can be used to achieve particular goals or to form intentions regarding their achievement. Given both semantics, our formalism additionally serves as an executable specification language suitable for constructing complex systems. A system based on this formalism is described, and examples involving control of an autonomous robot and fault diagnosis for NASA's space shuttle are provided.

  9. Neonatal Handling Affects Durably Bonding and Social Development

    PubMed Central

    Henry, Séverine; Richard-Yris, Marie-Annick; Tordjman, Sylvie; Hausberger, Martine

    2009-01-01

    The neonatal period in humans and in most mammals is characterized by intense mother-young interactions favoring pair bonding and the adaptation of neonates to their new environment. However, in many post-delivery procedures, human babies commonly experience combined maternal separation and intense handling for about one hour post-birth. Currently, the effects of such disturbances on later attachment and on the development of newborns are still debated: clearly, further investigations are required. As animals present good models for controlled experimentation, we chose domestic horses to investigate this issue. Horses, like humans, are characterized by single births, long lactating periods and selective mother-infant bonds. Routine postnatal procedures for foals, as for human babies, also involve intense handling and maternal separation. In the present study, we monitored the behavior of foals from early stages of development to “adolescence”, in a normal ecological context (social groups with adults and peers). Experimental foals, separated from their mothers and handled for only 1 hour post-birth, were compared to control foals, left undisturbed after birth. Our results revealed short- and long-term effects of this unique neonatal experience on attachment and subsequent social competences. Thus, experimental foals presented patterns of insecure attachment to their mothers (strong dependence on their mothers, little play) and impaired social competences (social withdrawal, aggressiveness) at all ages. We discuss these results in terms of mother-young interactions, timing of interactions and relationships between bonding and subsequent social competences. Our results indicate that this ungulate species could become an interesting animal model. To our knowledge, this is the first clear demonstration that intervention just after birth affects bonding and subsequent social competences (at least until “adolescence”). It opens new research directions for studies

  10. Durable zinc oxide-containing sorbents for coal gas desulfurization

    SciTech Connect

    Siriwardane, R.V.

    1994-12-31

    Durable zinc-oxide containing sorbent pellets for removing hydrogen sulfide from a gas stream at an elevated temperature are made up to contain titania as a diluent, high-surface-area silica gel as a matrix material, and a binder. These materials are mixed, moistened, and formed into pellets, which are then dried and calcined. The resulting pellets undergo repeated cycles of sulfidation and regeneration without loss of reactivity and without mechanical degradation. Regeneration of the pellets is carried out by contacting the bed with an oxidizing gas mixture.

  11. Toward improved durability in advanced aircraft engine hot sections

    NASA Technical Reports Server (NTRS)

    Sokolowski, Daniel E. (Editor)

    1989-01-01

    The conference on durability improvement methods for advanced aircraft gas turbine hot-section components discussed NASA's Hot Section Technology (HOST) project, advanced high-temperature instrumentation for hot-section research, the development and application of combustor aerothermal models, and the evaluation of a data base and numerical model for turbine heat transfer. Also discussed are structural analysis methods for gas turbine hot section components, fatigue life-prediction modeling for turbine hot section materials, and the service life modeling of thermal barrier coatings for aircraft gas turbine engines.

  12. Flexible, durable proton energy degraders for the GE PETtrace

    SciTech Connect

    Engle, J. W.; Gagnon, K.; Severin, G. W.; Valdovinos, H. F.; Nickles, R. J.; Barnhart, T. E.

    2012-12-19

    In order to limit the formation of radioisotopic impurities during proton bombardments of solid targets, two methods of introducing degrader foils into the beam upstream of the target were tested. The first design uses a 445 {mu}m thick fixed degrader machined from a single piece of aluminum. The second design permits introduction of foils made of any material and was tested with foils as thick as 635 {mu}m (also aluminium). In both cases, the foils are cooled with by water flowing through an annular channel outside the radius of the beam. Both designs proved durable and tolerated proton beam currents in excess of 80 {mu}A.

  13. PEM Fuel Cell Freeze Durability and Cold Start Project

    SciTech Connect

    Patterson, T.; O'Neill, Jonathan

    2008-01-02

    UTC has taken advantage of the unique water management opportunities inherent in micro-porous bipolar-plates to improve the cold-start performance of its polymer electrolyte fuel cells (PEFC). Diagnostic experiments were used to determine the limiting factors in micro-porous plate PEFC freeze performance and the causes of any performance decay. Alternative cell materials were evaluated for their freeze performance. Freeze-thaw cycling was also performed to determine micro-porous plate PEFC survivability. Data from these experiments has formed the basis for continuing development of advanced materials capable of supporting DOE's cold-start and durability objectives.

  14. Durable, Low-cost, Improved Fuel Cell Membranes

    SciTech Connect

    Chris Roger; David Mountz; Wensheng He; Tao Zhang

    2011-03-17

    The development of low cost, durable membranes and membranes electrode assemblies (MEAs) that operate under reduced relative humidity (RH) conditions remain a critical challenge for the successful introduction of fuel cells into mass markets. It was the goal of the team lead by Arkema, Inc. to address these shortages. Thus, this project addresses the following technical barriers from the fuel cells section of the Hydrogen Fuel Cells and Infrastructure Technologies Program Multi-Year Research, Development and Demonstration Plan: (A) Durability (B) Cost Arkema’s approach consisted of using blends of polyvinylidenefluoride (PVDF) and proprietary sulfonated polyelectrolytes. In the traditional approach to polyelectrolytes for proton exchange membranes (PEM), all the required properties are “packaged” in one macromolecule. The properties of interest include proton conductivity, mechanical properties, durability, and water/gas transport. This is the case, for example, for perfluorosulfonic acid-containing (PFSA) membranes. However, the cost of these materials is high, largely due to the complexity and the number of steps involved in their synthesis. In addition, they suffer other shortcomings such as mediocre mechanical properties and insufficient durability for some applications. The strength and originality of Arkema’s approach lies in the decoupling of ion conductivity from the other requirements. Kynar® PVDF provides an exceptional combination of properties that make it ideally suited for a membrane matrix (Kynar® is a registered trademark of Arkema Inc.). It exhibits outstanding chemical resistance in highly oxidative and acidic environments. In work with a prior grant, a membrane known as M41 was developed by Arkema. M41 had many of the properties needed for a high performance PEM, but had a significant deficiency in conductivity at low RH. In the first phase of this work, the processing parameters of M41 were explored as a means to increase its proton

  15. Chemically durable phosphate glasses and a method for their preparation

    DOEpatents

    Day, D.E.; Wilder, J.A. Jr.

    The chemical durability of alkali phosphate glasses is improved by incorporation of up to 23 weight percent of nitrogen. A typical phosphate glass contains: 10 to 60 mole % of Li/sub 2/O, Na/sub 2/O or K/sub 2/O; 5 to 40 mole % of BaO or CaO; 0 to 1 to 10 mole % of Al/sub 2/O/sub 3/; and 40 to 70 mole % of P/sub 2/O/sub 5/. Nitrides, such as AlN, are the favored additives.

  16. Durable zinc oxide-containing sorbents for coal gas desulfurization

    DOEpatents

    Siriwardane, Ranjani V.

    1996-01-01

    Durable zinc-oxide containing sorbent pellets for removing hydrogen sulfide from a gas stream at an elevated temperature are made up to contain titania as a diluent, high-surface-area silica gel, and a binder. These materials are mixed, moistened, and formed into pellets, which are then dried and calcined. The resulting pellets undergo repeated cycles of sulfidation and regeneration without loss of reactivity and without mechanical degradation. Regeneration of the pellets is carried out by contacting the bed with an oxidizing gas mixture.

  17. Methods for Using Durable Adhesively Bonded Joints for Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III (Inventor); Lundgren, Eric C. (Inventor)

    2016-01-01

    Systems, methods, and apparatus for increasing durability of adhesively bonded joints in a sandwich structure. Such systems, methods, and apparatus includes an first face sheet and an second face sheet as well as an insert structure, the insert structure having a first insert face sheet, a second insert face sheet, and an insert core material. In addition, sandwich core material is arranged between the first face sheet and the second face sheet. A primary bondline may be coupled to the face sheet(s) and the splice. Further, systems, methods, and apparatus of the present disclosure advantageously reduce the load, provide a redundant path, reduce structural fatigue, and/or increase fatigue life.

  18. Structural Integrity and Durability of Reusable Space Propulsion Systems

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A two-day conference on the structural integrity and durability of reusable space propulsion systems was held on 14 to 15 May 1991 at the NASA Lewis Research Center. Presentations were made by industry, university, and government researchers organized into four sessions: (1) aerothermodynamic loads; (2) instrumentation; (3) fatigue, fracture, and constitutive modeling; and (4) structural dynamics. The principle objectives were to disseminate research results and future plans in each of four areas. This publication contains extended abstracts and the visual material presented during the conference. Particular emphasis is placed on the Space Shuttle Main Engine (SSME) and the SSME turbopump.

  19. Durable silver thin film coating for diffraction gratings

    DOEpatents

    Wolfe, Jesse D.; Britten, Jerald A.; Komashko, Aleksey M.

    2006-05-30

    A durable silver film thin film coated non-planar optical element has been developed to replace Gold as a material for fabricating such devices. Such a coating and resultant optical element has an increased efficiency and is resistant to tarnishing, can be easily stripped and re-deposited without modifying underlying grating structure, improves the throughput and power loading of short pulse compressor designs for ultra-fast laser systems, and can be utilized in variety of optical and spectrophotometric systems, particularly high-end spectrometers that require maximized efficiency.

  20. Structural Durability of Damaged Metallic Panel Repaired with Composite Patches

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C.

    1997-01-01

    Structural durability/damage tolerance characteristics of an aluminum tension specimen possessing a short crack and repaired by applying a fiber composite surface patch is investigated via computational simulation. The composite patch is made of graphite/epoxy plies with various layups. An integrated computer code that accounts for all possible failure modes is utilized for the simulation of combined fiber-composite/aluminum structural degradation under loading. Damage initiation, growth, accumulation, and propagation to structural fracture are included in the simulation. Results show the structural degradation stages due to tensile loading and illustrate the use of computational simulation for the investigation of a composite patch repaired cracked metallic panel.

  1. Water-thinnable polymers for durable coatings for different materials

    NASA Astrophysics Data System (ADS)

    Jankowski, Piotr; Kijowska, Dorota

    2014-05-01

    The methods of obtaining water-thinnable polymers - water-thinnable unsaturated polyester resins (WTUPR) - by polycondensation were elaborate and optimized. As hydrophilic monomers different types of sulfonate monomers were used. The monomers, with sulfonate groups and other reactive groups, were obtained by sulfonation of organic compounds with satisfactory yield. All products were analyzed by 1H NMR and 13C NMR spectra. WTUPR were used as polymeric binders for coatings applications. Coatings with relatively high pendulum hardness, good properties and durability, useful for practical applications, were obtained. Typical existing equipment for the production of unsaturated polyester resins can be applied for the industrial preparation of WTUPR.

  2. Durability of Polymeric Encapsulation Materials for Concentrating Photovoltaic Systems (Presentation)

    SciTech Connect

    Miller, D. C.; Muller, M.; Kempe, M. D.; Araki, K.; Kennedy, C. E.; Kurtz, S. R.

    2011-04-01

    Presented at the 7th International Conference on Concentrating Photovoltaic Systems (CPV-7), 4-6 April 2011, Las Vegas, Nevada. Many concentrating photovoltaic (CPV) systems use a polymeric encapsulant to couple an optical component and/or coverglass to the cell. In that location, the encapsulation improves the transmission of concentrated optical flux through interfaces(s) while protecting the cell from the environment. The durability of encapsulation materials, however, is not well established relative to the desired service life of 30 years. Therefore, we have initiated a screen test to identify the field-induced failure modes for a variety of popular PV encapsulation materials.

  3. Water-thinnable polymers for durable coatings for different materials

    SciTech Connect

    Jankowski, Piotr Kijowska, Dorota

    2014-05-15

    The methods of obtaining water-thinnable polymers - water-thinnable unsaturated polyester resins (WTUPR) - by polycondensation were elaborate and optimized. As hydrophilic monomers different types of sulfonate monomers were used. The monomers, with sulfonate groups and other reactive groups, were obtained by sulfonation of organic compounds with satisfactory yield. All products were analyzed by {sup 1}H NMR and {sup 13}C NMR spectra. WTUPR were used as polymeric binders for coatings applications. Coatings with relatively high pendulum hardness, good properties and durability, useful for practical applications, were obtained. Typical existing equipment for the production of unsaturated polyester resins can be applied for the industrial preparation of WTUPR.

  4. Oral isotretinoin in photoaging: objective histological evidence of efficacy and durability*

    PubMed Central

    Bravo, Bruna Souza Felix; Azulay, David Rubem; Luiz, Ronir Raggio; Mandarim-De-Lacerda, Carlos Alberto; Cuzzi, Tullia; Azulay, Mônica Manela

    2015-01-01

    BACKGROUND The off-label use of oral isotretinoin in photoaging is a therapeutic tool that has been used by dermatologists. There are few studies to corroborate its effectiveness and durability. OBJECTIVES To assess, both clinically and histologically, the changes caused by the use of oral isotretinoin in skin photoaging as well as the duration of the effects. METHODS 20 female patients, aged 45-50 years, with phototypes II-VI, none of whom had experienced menopause, were treated with 20mg oral isotretinoin, 3 days a week, for 12 weeks. They underwent clinical analysis and skin biopsies in the pre-auricular region, while histologic cuts enabled assessment of the solar elastosis level and morphologic analysis. RESULTS Clinically, patients, as well as the researching and the assessor physicians, noticed improvement in skin quality. One patient presented severe solar elastosis, 11 manifested the moderate form, while 8 presented the discreet type. According to histological analysis, 65% of the patients revealed alteration in the distribution and thickness of the elastic fibers, which can be interpreted as a histological improvement, while 60% showed an increase in collagen density. We observed an increase in collagen density, from 51.2% to 57.4%, (p=0.004). At the end of the 12-week follow-up period, this density decreased to 54.7% (p=0.050). There was an increase in the density of elastic fibers, from 26.5% to 31.3%, (p=0.02), which had dropped to 27.5% at the end of the 12-week follow-up period. CONCLUSIONS The study confirmed the role of oral isotretinoin in remodeling the extracellular matrix against photoaging, as well as its durability after 12 weeks, especially when we consider collagen fibers. PMID:26375216

  5. Effect of structural change of collagen fibrils on the durability of dentin bonding.

    PubMed

    Yang, Bin; Adelung, Rainer; Ludwig, Klaus; Bössmann, Klaus; Pashley, David H; Kern, Matthias

    2005-08-01

    This study investigates the effect of structural changes of collagen fibrils on the bonding durability of a total etch luting resin (Super-Bond C&B) and a self-etching luting resin (Panavia F 2.0) to dentin. An atomic force microscope (AFM) was used to observe structural changes of intact dentin collagen fibrils after acidic conditionings of two bonding systems. After 90 d water storage and 15,000 thermal cycles (TC) as artificial aging, micro-tensile bond strength (microTBS) was utilized to evaluate the bonding durability of the two bonding systems to dentin. microTBS after 1 d or 90 d water storage without TC were separately measured in control groups. A cross-banding periodicity of about 67 nm along collagen fibrils was seen on demineralized intertubular dentin surfaces in AFM images. For both luting resins, thermal cycling decreased (p < 0.05) microTBS of 1 d and 90 d, compared to controls. Scanning electron microscope and transmission electron microscopic examinations revealed that the top and bottom of hybrid layer (HL) were weak links in the bonding interface over time. The results suggest that the top of HL contains disorganized collagen fibrils from the smear layer which degrade over time. AFM results indicate that the demineralized intact collagen fibrils beneath the smear layer were not denatured during acidic conditioning. However, these collagen fibrils may be structurally unstable due to poor infiltration by resin or loss of resin protection within the HL over time, reducing the long-term microTBS. This process was accelerated by thermal fatigue cycling.

  6. Durability of metals from archaeological objects, metal meteorites, and native metals

    SciTech Connect

    Johnson, A.B. Jr.; Francis, B.

    1980-01-01

    Metal durability is an important consideration in the multi-barrier nuclear waste storage concept. This study summarizes the ancient metals, the environments, and factors which appear to have contributed to metal longevity. Archaeological and radiochemical dating suggest that human use of metals began in the period 6000 to 7000 BC. Gold is clearly the most durable, but many objects fashioned from silver, copper, bronze, iron, lead, and tin have survived for several thousand years. Dry environments, such as tombs, appear to be optimum for metal preservation, but some metals have survived in shipwrecks for over a thousand years. The metal meteorites are Fe-base alloys with 5 to 60 wt% Ni and minor amounts of Co, I, and S. Some meteoritic masses with ages estimated to be 5,000 to 20,000 years have weathered very little, while other masses from the same meteorites are in advanced stages of weathering. Native metals are natural metallic ores. Approximately five million tonnes were mined from native copper deposits in Michigan. Copper masses from the Michigan deposits were transported by the Pleistocene glaciers. Areas on the copper surfaces which appear to represent glacial abrasion show minimal corrosion. Dry cooling tower technology has demonstrated that in pollution-free moist environments, metals fare better at temperatures above than below the dewpoint. Thus, in moderate temperature regimes, elevated temperatures may be useful rather than detrimental for exposures of metal to air. In liquid environments, relatively complex radiolysis reactions can occur, particularly where multiple species are present. A dry environment largely obviates radiolysis effects.

  7. Durable silver mirror with ultra-violet thru far infra-red reflection

    DOEpatents

    Wolfe, Jesse D.

    2010-11-23

    A durable highly reflective silver mirror characterized by high reflectance in a broad spectral range of about 300 nm in the UV to the far infrared (.about.10000 nm), as well as exceptional environmental durability. A high absorptivity metal underlayer is used which prevents the formation of a galvanic cell with a silver layer while increasing the reflectance of the silver layer. Environmentally durable overcoat layers are provided to enhance mechanical and chemical durability and protect the silver layer from corrosion and tarnishing, for use in a wide variety of surroundings or climates, including harsh or extreme environments.

  8. 32 CFR 57.6 - Procedures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... INTERVENTION AND SPECIAL EDUCATION SERVICES TO ELIGIBLE DOD DEPENDENTS § 57.6 Procedures. (a) The procedures..., ages 3 through 21 years, inclusive, on IEPs are prescribed in appendix B of this part. (c) The..., inclusive, are prescribed in appendix C of this part (d) Procedural safeguards and parent and student...

  9. Evaluation of the Durability of Flexible Barrier Materials

    SciTech Connect

    Kempe, Michael D.; Nobles, Dylan L.; Weigel, Mark D.; Nachtigal, Alan K.; Roehrig, Mark A.; Berniard, Tracie J.; Spagnola, Joseph C.; Schubert, Charlene M.

    2015-06-14

    To enable the production of lightweight photovoltaic modules, it is desired to use thin film absorbers on metal substrates in a flexible package. To do this with a polymer based frontsheet, it is estimated that a water vapor transmission rate (WVTR) less than 10-4 g/m2/day must be achieved and maintained through the expected life of the module. Barrier-frontsheet films have been developed at 3M with very low permeation rates and evaluated for their long term durability with respect to WVTR and optical transmittance. After exposure to 2500 h of 10 UV suns at 105 degrees C, one design was found which experienced negligible loss in optical transmission while maintaining a WVTR well below the required 10-4 g/m2/day. Further accelerated tests were conducted at different stress levels. For some less durable designs we were able to obtain degradation acceleration factors suggesting the highest exposure was equal to between 4.4 and 10 y on a roof.

  10. [Effectivity and durability of telescopic dentures on abutment teeth].

    PubMed

    van den Wijngaarden, E; van Pelt, A W J; Meisberger, E W; Tams, J; Cune, M S

    2016-03-01

    In a study, the effectivity and durability of telescopic dentures on abutment teeth provided with telescope crowns were investigated. The prognosis for the prosthetic structure and for the abutment teeth were both investigated. The survival rate of 234 telescopic dentures (886 abutment teeth) in 147 patients in a general dental practice were retrospectively evaluated on the basis of a status study. The mean survival rate was calculated. This is the moment when 50% of the telescopic dentures had failed. For telescopic dentures in the maxilla, this was 22.3±2.8 years, which did not represent a statistically significant difference from the mandible (20.9±1.9 years). Of the 886 abutment teeth that were used, 127 (14.3%) were extracted after an average period of 11.7 years. Periodontal complications were the primary reason for extraction. Based on this investigation, one could conclude that telescopic dentures are also a durable and sustainable solution in the long term. Loss of abutment teeth is relatively rare and has limited influence on the survival of the prosthetic structure. PMID:26973985

  11. Durability of conventional concretes containing black rice husk ash.

    PubMed

    Chatveera, B; Lertwattanaruk, P

    2011-01-01

    In this study, black rice husk ash (BRHA) from a rice mill in Thailand was ground and used as a partial cement replacement. The durability of conventional concretes with high water-binder ratios was investigated including drying shrinkage, autogenous shrinkage, depth of carbonation, and weight loss of concretes exposed to hydrochloric (HCl) and sulfuric (H(2)SO(4)) acid attacks. Two different replacement percentages of cement by BRHA, 20% and 40%, and three different water-binder ratios (0.6, 0.7 and 0.8) were used. The ratios of paste volume to void content of the compacted aggregate (γ) were 1.2, 1.4, and 1.6. As a result, when increasing the percentage replacement of BRHA, the drying shrinkage and depth of carbonation reaction of concretes increased. However, the BRHA provides a positive effect on the autogenous shrinkage and weight loss of concretes exposed to hydrochloric and sulfuric acid attacks. In addition, the resistance to acid attack was directly varied with the (SiO(2) + Al(2)O(3) + Fe(2)O(3))/CaO ratio. Results show that ground BRHA can be applied as a pozzolanic material and also improve the durability of concrete.

  12. Progressive Damage Modeling of Durable Bonded Joint Technology

    NASA Technical Reports Server (NTRS)

    Leone, Frank A.; Davila, Carlos G.; Lin, Shih-Yung; Smeltzer, Stan; Girolamo, Donato; Ghose, Sayata; Guzman, Juan C.; McCarville, Duglas A.

    2013-01-01

    The development of durable bonded joint technology for assembling composite structures for launch vehicles is being pursued for the U.S. Space Launch System. The present work is related to the development and application of progressive damage modeling techniques to bonded joint technology applicable to a wide range of sandwich structures for a Heavy Lift Launch Vehicle. The joint designs studied in this work include a conventional composite splice joint and a NASA-patented Durable Redundant Joint. Both designs involve a honeycomb sandwich with carbon/epoxy facesheets joined with adhesively bonded doublers. Progressive damage modeling allows for the prediction of the initiation and evolution of damage. For structures that include multiple materials, the number of potential failure mechanisms that must be considered increases the complexity of the analyses. Potential failure mechanisms include fiber fracture, matrix cracking, delamination, core crushing, adhesive failure, and their interactions. The joints were modeled using Abaqus parametric finite element models, in which damage was modeled with user-written subroutines. Each ply was meshed discretely, and layers of cohesive elements were used to account for delaminations and to model the adhesive layers. Good correlation with experimental results was achieved both in terms of load-displacement history and predicted failure mechanisms.

  13. Enhanced durability of desulfurization sorbents for fluidized-bed applications

    SciTech Connect

    Gupta, R.P.; Gangwal, S.K.

    1991-06-01

    Advanced integrated gasification combined cycle (IGCC) power systems require the development of high-temperature desulfurization sorbents capable of removing hydrogen sulfide from coal gasifier down to very low levels. The objective of this investigation was to identify and demonstrate methods for enhancing the long-term chemical reactivity and mechanical strength of zinc ferrite, a leading regenerable sorbent, for fluidized-bed applications. Fluidized sorbent beds offer significant potential in IGCC systems because of their ability to control the highly exothermic regeneration involved. However, fluidized beds require a durable, attrition-resistant sorbent in the 100--300 {mu}m size range. A bench-scale high-temperature, high- pressure (HTHP) fluidized-bed reactor (7.6-cm I.D.) system capable of operating up to 24 atm and 800{degree}C was designed, built and tested. A total of 175 sulfidation-regeneration cycles were carried out using KRW-type coal gas with various zinc ferrite formulations. A number of sorbent manufacturing techniques including spray drying, impregnation, crushing and screening, and granulation were investigated. While fluidizable sorbents prepared by crushing durable pellets and screening had acceptable sulfur capacity, they underwent excessive attrition during multicycle testing. The sorbent formulations prepared by a proprietary technique were found to have excellent attrition resistance and acceptable chemical reactivity during multicycle testing. However, zinc ferrite was found to be limited to 550{degree}C, beyond which excessive sorbent weakening due to chemical transformations, e.g., iron oxide reduction, was observed.

  14. Highly efficient and durable TiN nanofiber electrocatalyst supports.

    PubMed

    Kim, Hyun; Cho, Min Kyung; Kwon, Jeong An; Jeong, Yeon Hun; Lee, Kyung Jin; Kim, Na Young; Kim, Min Jung; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Nam, Suk Woo; Lim, Dong-Hee; Cho, EunAe; Lee, Kwan-Young; Kim, Jin Young

    2015-11-28

    To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via electrospinning and subsequent two-step thermal treatment processes as a support for the PEMFC catalyst. Pt catalyst nanoparticles (NPs) deposited on the TNFs (Pt/TNFs) were electrochemically characterized with respect to oxygen reduction reaction (ORR) activity and durability in an acidic medium. From the electrochemical tests, the TNF-supported Pt catalyst was better and more stable in terms of its catalytic performance compared to a commercially available carbon-supported Pt catalyst. For example, the initial oxygen reduction performance was comparable for both cases, while the Pt/TNF showed much higher durability from an accelerated degradation test (ADT) configuration. It is understood that the improved catalytic roles of TNFs on the supported Pt NPs for ORR are due to the high electrical conductivity arising from the extended connectivity, high inertness to the electrochemical environment and strong catalyst-support interactions. PMID:26489450

  15. Improved materials for durable rings, liners, and injector nozzles

    SciTech Connect

    Mehan, R.L.; Rairden, J.R.

    1990-06-01

    This report is the first Topical Report on the subject of Durability. The work was performed at GE's Research and Development Center (GE-CRD) in support of GE Transportations system's (GETS) effort to develop the necessary technology for future commercialization of a coal-fueled diesel power system. The technical areas covered are durable materials development for piston rings, cylinder liners, and injector nozzles. The development of an erosion-resistant nozzle for the coal-fueled locomotive was given the highest priority. Erosion tests demonstrated that nozzles built of diamond would withstand the erosive nature of the high-velocity slurry. A nozzle with diamond nozzles was designed, fabricated, and tested in a test engine. The development of piston rings and cylinder liners that could withstand the abrasive nature of the coal ash-deposited on the combustion liner was also a high priority activity. Bench scale tests were used to select optimized materials and processing conditions for plasma-deposited coatings. Tungsten carbide/cobalt was the material of choice for both the ring and liner. Small-scale engine components were built and tested. Finally, test were conducted to identify the optimum plasma spray processing conditions for deposits of tungsten carbide/cobalt mixtures. The results of these tests are described. 13 refs., 21 figs., 10 tabs.

  16. Vitrified metal finishing wastes I. Composition, density and chemical durability.

    PubMed

    Bingham, P A; Hand, R J

    2005-03-17

    Durable phosphate glasses were formed by vitrifying waste filter cakes from two metal finishing operations. Some melts formed crystalline components during cooling. Compositional analysis of dried, heat treated and vitrified samples was made using energy-dispersive X-ray spectroscopy, X-ray fluorescence spectroscopy, inductively-coupled plasma spectroscopy and Leco induction furnace combustion analysis. Hydrolytic dissolution, measured by an adapted product consistency test, was reduced by up to 3 orders of magnitude upon heat treatment or vitrification, surpassing the performance of borosilicate glass in some cases. This was attributed to the high levels of iron and zinc in the wastes, which greatly improve the durability of phosphate glasses. One of the wastes arose from a metal phosphating process and was particularly suitable for vitrification due to its high P2O5 content and favourable melting behaviour. The other waste, which arose from a number of processes, was less suitable as it had a low P2O5 content and during heating it emitted harmful corrosive gases and underwent violent reactions. Substantial volume reductions were obtained by heat treatment and vitrification of both wastes. Compositions and performances of some vitrified wastes were comparable with those of glasses which are under consideration for the immobilisation of toxic and nuclear wastes.

  17. Integrated approach for investigating the durability of self-consolidating concrete to sulfate attack

    NASA Astrophysics Data System (ADS)

    Bassuoni, Mohamed Tamer F.

    factor from multiple performance criteria was created for the ammonium sulfate exposure. Environmental charts were developed to determine the level of aggression associated with sodium sulfate attack from temperature, RH and degree of wetting-drying expected in service. This novel modeling approach showed promising success in handling complex durability topics such as the sulfate attack of concrete, which involves non-linearity, ambiguity and interface with operator approximation. The current thesis provides needed fundamental knowledge on the durability of a wide scope of SCC mixtures to various sulfate attack exposure scenarios. It elucidates complex deterioration mechanisms and failure modes of cement-based materials under multi-mechanistic aging processes. It also proposes carefully engineered integrated sulfate attack tests that replicate various sulfate attack exposure regimes, which could be refined and standardized in the future. In addition, the current work introduced original knowledge-based smart models capable of handling uncertainty and providing reliable predictions for the behaviour of concrete under external sulfate attack. The models do not require conducting exhaustive laboratory experiments and/or making assumptions, thus facilitating the selection of optimum concrete mixtures for a specified exposure. Overall, this research should effectively contribute to the development of performance-based standards and specifications for, and improvement of durability-based design and life-cycle analysis of concrete structures subjected to external sulfate attack. Keywords. Sulfate attack, self-consolidating concrete, integrated testing, composite cements, air-entrainment, hybrid fibres, full immersion, cations, pH, wetting-drying, partial immersion, freezing-thawing, cyclic cold-hot conditions, flexural loading, thaumasite, salt crystallization, fuzzy, neuro-fuzzy, systems.

  18. Final Report - MEA and Stack Durability for PEM Fuel Cells

    SciTech Connect

    Yandrasits, Michael A.

    2008-02-15

    Proton exchange membrane fuel cells are expected to change the landscape of power generation over the next ten years. For this to be realized one of the most significant challenges to be met for stationary systems is lifetime, where 40,000 hours of operation with less than 10% decay is desired. This project conducted fundamental studies on the durability of membrane electrode assemblies (MEAs) and fuel cell stack systems with the expectation that knowledge gained from this project will be applied toward the design and manufacture of MEAs and stack systems to meet DOE’s 2010 stationary fuel cell stack systems targets. The focus of this project was PEM fuel cell durability – understanding the issues that limit MEA and fuel cell system lifetime, developing mitigation strategies to address the lifetime issues and demonstration of the effectiveness of the mitigation strategies by system testing. To that end, several discoveries were made that contributed to the fundamental understanding of MEA degradation mechanisms. (1) The classically held belief that membrane degradation is solely due to end-group “unzipping” is incorrect; there are other functional groups present in the ionomer that are susceptible to chemical attack. (2) The rate of membrane degradation can be greatly slowed or possibly eliminated through the use of additives that scavenge peroxide or peroxyl radicals. (3) Characterization of GDL using dry gases is incorrect due to the fact that fuel cells operate utilizing humidified gases. The proper characterization method involves using wet gas streams and measuring capillary pressure as demonstrated in this project. (4) Not all Platinum on carbon catalysts are created equally – the major factor impacting catalyst durability is the type of carbon used as the support. (5) System operating conditions have a significant impact of lifetime – the lifetime was increased by an order of magnitude by changing the load profile while all other variables remain

  19. Solubility and durability of cardanol derived plasticizers for soft PVC

    NASA Astrophysics Data System (ADS)

    Greco, Antonio; Ferrari, Francesca; Velardi, Rosario; Frigione, Mariaenrica; Maffezzoli, Alfonso

    2015-12-01

    This work is aimed to study the suitability of cardanol derivatives as primary plasticizer for PVC. The innovative plasticizer is obtained by chemical modification of cardanol, a natural, renewable resource, obtained as a by-product of the cashew nut shell industry. Cardanol derived plasticizers (CDP) were prepared by following various procedures, that allow obtaining different degrees of conversion of cardanol. Rheological and ageing tests were made on soft PVC produced by the addition of CDP;results obtained were compared to soft PVC attained by the use of di-ethyl-hexyl-phthalate (DEHP) and other natural derived plasticizers already used in PVC industry (epoxidated soybean oil, ESBO, and acetic acid ester, AAE).A high dependence on the degree of conversion was found: CDP with a good degree of conversion have similar gelation temperature and diffusion coefficient compared to DEHP based plastisols. Otherwise,CDP with a low degree of conversionshow a higher diffusion coefficient, index of a fast migration of the plasticizer from soft PVC.

  20. Antiseptic skin agents for percutaneous procedures.

    PubMed

    Lepor, Norman E; Madyoon, Hooman

    2009-01-01

    Infections associated with percutaneously implanted devices, such as pacemakers, internal cardiac defibrillators, and endovascular prostheses, create difficult and complex clinical scenarios because management can entail complete device removal, antibiotic therapy, and prolonged hospitalization. A source for pathogens is often thought to be the skin surface, making skin preparation at the time of the procedure a critical part of minimizing implantation of infected devices and prostheses. The most common skin preparation agents used today include products containing iodophors or chlorhexidine gluconate. Agents are further classified by whether they are aqueous-based or alcoholbased solutions. Traditional aqueous-based iodophors, such as povidone-iodine, are one of the few products that can be safely used on mucous membrane surfaces. Alcohol-based solutions are quick, sustained, and durable, with broader spectrum antimicrobial activity. These agents seem ideal for percutaneous procedures associated with prosthesis implantation, when it is critical to minimize skin colony counts to prevent hardware infection.

  1. Durability of polymeric materials used in zinc/bromine flow batteries

    NASA Astrophysics Data System (ADS)

    Arnold, C., Jr.

    The lifetimes of zinc/bromine flow batteries may be limited by the durability of components which are fabricated from thermoplastic materials and exposed to the bromine-containing electrolyte. Examples of such components are flowframes and carbon-filled plastic electrodes. In early versions of the zinc/bromine battery, flowframes and electrodes were made from polypropylene and copolymers of propylene and ethylene. In later versions of the zinc/bromine battery, polyvinyl chloride (PVC) was used as the material to fabricate flowframes and polyethylene was used as the material used to fabricate both flowframes and electrodes. We found that carbon-plastic electrodes made from polypropylene or polypropylene rich copolymers were swelled and chemically attacked by the bromine-containing electrolytes. As a result, warpage occurred and the battery failed. On the basis of accelerated aging studies we estimated the lifetimes of the electrode and its polypropylene based component to be 96 and 10 months, respectively. The enhanced stability of the electrode was attributed to the presence of carbon which is known to be an antioxidant for thermoxidation. In accelerated exposure tests, bromine-containing electrolytes were also found to attack and leach out the additives used in PVC flowframes. PVC itself was only slightly degraded by the electrolyte. A commercial fluorocarbon, Tefzel, which contains no additives, was determined to be stable in bromine-containing electrolytes and is recommended as a replacement for PVC. Currently, aging studies on carbon-filled polyethylene electrodes are in progress.

  2. An improved mechanically durable electrophoresis gel matrix that is fully compatible with fluorescence-based protein detection technologies.

    PubMed

    Schulenberg, Birte; Arnold, Brad; Patton, Wayne F

    2003-07-01

    Unfortunately, conventional large-format polyacrylamide gels are mechanically fragile, often tearing during the subsequent manipulations required for visualization of the proteins. This problem is compounded when large-format two-dimensional gels are subjected to multiple staining procedures in order to detect different classes of proteins, such as total protein, phosphoproteins, and glycoproteins. A mechanically durable liquid polyacrylamide-based matrix has been developed that, upon polymerization, facilitates the handling of one-dimensional and two-dimensional gels. The matrix, referred to as Rhinohide liquid acrylamide, is stable as a refrigerated solution for up to one year, and forms a polymer-reinforced polyacrylamide gel suitable for electrophoresis, upon addition of catalysts. The matrix is superior to previously reported durable gel matrices in that it does not cause distortion of high-molecular-weight bands and does not suffer from other spot morphology artifacts, such as doubling of protein spots in the molecular weight dimension. The matrix is particularly valuable for the analysis of proteins applying multiple applications of fluorescent dyes, as required with serial staining of proteins for phosphorylation, glycosylation, and total protein expression, using Pro-Q Diamond phosphoprotein stain, Pro-Q Emerald glycoprotein stain and SYPRO Ruby protein gel stain, respectively.

  3. An improved mechanically durable electrophoresis gel matrix that is fully compatible with fluorescence-based protein detection technologies.

    PubMed

    Schulenberg, Birte; Arnold, Brad; Patton, Wayne F

    2003-07-01

    Unfortunately, conventional large-format polyacrylamide gels are mechanically fragile, often tearing during the subsequent manipulations required for visualization of the proteins. This problem is compounded when large-format two-dimensional gels are subjected to multiple staining procedures in order to detect different classes of proteins, such as total protein, phosphoproteins, and glycoproteins. A mechanically durable liquid polyacrylamide-based matrix has been developed that, upon polymerization, facilitates the handling of one-dimensional and two-dimensional gels. The matrix, referred to as Rhinohide liquid acrylamide, is stable as a refrigerated solution for up to one year, and forms a polymer-reinforced polyacrylamide gel suitable for electrophoresis, upon addition of catalysts. The matrix is superior to previously reported durable gel matrices in that it does not cause distortion of high-molecular-weight bands and does not suffer from other spot morphology artifacts, such as doubling of protein spots in the molecular weight dimension. The matrix is particularly valuable for the analysis of proteins applying multiple applications of fluorescent dyes, as required with serial staining of proteins for phosphorylation, glycosylation, and total protein expression, using Pro-Q Diamond phosphoprotein stain, Pro-Q Emerald glycoprotein stain and SYPRO Ruby protein gel stain, respectively. PMID:12872220

  4. Durable and self-healing superamphiphobic coatings repellent even to hot liquids.

    PubMed

    Li, Bucheng; Zhang, Junping

    2016-02-14

    Durable and self-healing superamphiphobic coatings with high repellency to both cool and hot liquids are successfully prepared on various substrates by the combination of rodlike palygorskite and organosilanes via spray-coating. The coatings feature high mechanical, environmental and chemical durability, and are self-healing.

  5. 75 FR 2105 - Publication of OIG Updated Special Fraud Alert on Telemarketing by Durable Medical Equipment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ... Alert on Telemarketing by Durable Medical Equipment Suppliers AGENCY: Office of Inspector General (OIG... Special Fraud Alert addressing telemarketing by durable medical equipment (DME) suppliers. For the most part, OIG Special Fraud Alerts address national trends in health care fraud, including...

  6. Durable and self-healing superamphiphobic coatings repellent even to hot liquids.

    PubMed

    Li, Bucheng; Zhang, Junping

    2016-02-14

    Durable and self-healing superamphiphobic coatings with high repellency to both cool and hot liquids are successfully prepared on various substrates by the combination of rodlike palygorskite and organosilanes via spray-coating. The coatings feature high mechanical, environmental and chemical durability, and are self-healing. PMID:26758697

  7. Contact and Bending Durability Calculation for Spiral-Bevel Gears

    NASA Technical Reports Server (NTRS)

    Vijayakar, Sandeep

    2016-01-01

    The objective of this project is to extend the capabilities of the gear contact analysis solver Calyx, and associated packages Transmission3D, HypoidFaceMilled, HypoidFaceHobbed. A calculation process for the surface durability was implemented using the Dowson-Higginson correlation for fluid film thickness. Comparisons to failure data from NASA's Spiral Bevel Gear Fatigue rig were carried out. A bending fatigue calculation has been implemented that allows the use of the stress-life calculation at each individual fillet point. The gears in the NASA test rig did not exhibit any bending fatigue failure, so the bending fatigue calculations are presented in this report by using significantly lowered strength numbers.

  8. A relational approach to durable poverty, inequality and power.

    PubMed

    Mosse, David

    2010-01-01

    The article argues for what can be called a 'relational' approach to poverty: one that first views persistent poverty as the consequence of historically developed economic and political relations, and second, that emphasises poverty and inequality as an effect of social categorisation and identity, drawing in particular on the experience of adivasis ("tribals") and dalits ("untouchables") subordinated in Indian society. The approach follows Charles Tilly's Durable Inequality in combining Marxian ideas of exploitation and dispossession with Weberian notions of social closure. The article then draws on the work of Steven Lukes, Pierre Bourdieu and Arjun Appadurai to argue for the need to incorporate a multidimensional conception of power; including not only power as the direct assertion of will but also 'agenda-setting power' that sets the terms in which poverty becomes (or fails to become) politicised, and closely related to power as political representation. This sets the basis for discussion of the politics of poverty and exclusion.

  9. A relational approach to durable poverty, inequality and power.

    PubMed

    Mosse, David

    2010-01-01

    The article argues for what can be called a 'relational' approach to poverty: one that first views persistent poverty as the consequence of historically developed economic and political relations, and second, that emphasises poverty and inequality as an effect of social categorisation and identity, drawing in particular on the experience of adivasis ("tribals") and dalits ("untouchables") subordinated in Indian society. The approach follows Charles Tilly's Durable Inequality in combining Marxian ideas of exploitation and dispossession with Weberian notions of social closure. The article then draws on the work of Steven Lukes, Pierre Bourdieu and Arjun Appadurai to argue for the need to incorporate a multidimensional conception of power; including not only power as the direct assertion of will but also 'agenda-setting power' that sets the terms in which poverty becomes (or fails to become) politicised, and closely related to power as political representation. This sets the basis for discussion of the politics of poverty and exclusion. PMID:20737731

  10. The effect of coupling agents on composite durability

    SciTech Connect

    Macturk, K.S.; Schultheisz, C.R.; Hunston, D.L.; Schutte, C.L.

    1996-12-31

    The relationship between fiber surface treatments and glass fiber/epoxy composite durability was investigated. The type of silane coupling agent deposited on the fiber surface was varied, and the single fiber fragmentation test was used to measure strengths of the fiber and the fiber-matrix interface. The samples were tested dry and after conditioned in 75{degrees}C distilled water for up to 10 weeks. With dry samples the interface strengths varied with the reactivity of the silane deposited on the surface. Moisture exposure produced little change in fiber strengths and, for samples containing silane treated fibers, little change in interface strength, even when the silane was unreactive with the epoxy. In contrast, samples containing unsized fibers exhibited significant losses in interface strengths.

  11. Chemical durability of simulated nuclear glasses containing water

    SciTech Connect

    Li, H.; Tomozawa, M.

    1995-04-01

    The chemical durability of simulated nuclear waste glasses having different water contents was studied. Results from the product consistency test (PCT) showed that glass dissolution increased with water content in the glass. This trend was not observed during MCC-1 testing. This difference was attributed to the differences in reactions between glass and water. In the PCT, the glass network dissolution controlled the elemental releases, and water in the glass accelerated the reaction rate. On the other hand, alkali ion exchange with hydronium played an important role in the MCC-1. For the latter, the amount of water introduced into a leached layer from ion-exchange was found to be much greater than that of initially incorporated water in the glass. Hence, the initial water content has no effect on glass dissolution as measured by the MCC-1 test.

  12. Durability of commercial aircraft and helicopter composite structures

    NASA Technical Reports Server (NTRS)

    Dexter, H. B.

    1982-01-01

    The development of advanced composite technology during the past decade is discussed. Both secondary and primary components fabricated with boron, graphite, and Kevlar composites are evaluated. Included are spoilers, rudders, and fairings on commercial transports, boron/epoxy reinforced wing structure on C-130 military transports, and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on commercial helicopters. The development of composite structures resulted in advances in design and manufacturing technology for secondary and primary composite structures for commercial transports. Design concepts and inspection and maintenance results for the components in service are reported. The flight, outdoor ground, and controlled laboratory environmental effects on composites were also determined. Effects of moisture absorption, ultraviolet radiation, aircraft fuels and fluids, and sustained tensile stress are included. Critical parameters affecting the long term durability of composite materials are identified.

  13. Apparatus and method for laser deposition of durable coatings

    DOEpatents

    Veligdan, J.T.; Vanier, P.; Barletta, R.E.

    1995-08-15

    Method and apparatus are disclosed for depositing durable coatings onto the surface of a substrate without heating the entire substrate to high temperatures by using lasers to heat the substrate and dissociate a deposition gas. The apparatus comprises a deposition chamber for enclosing the substrate upon which a coating is to be deposited, gas delivery means for directing a flow of deposition gas on the substrate, a first laser for heating the substrate, and a second laser for irradiating the deposition gas to dissociate the gas. The method includes placing a substrate within a vacuum deposition chamber and directing a flow of deposition gas on the substrate. Then the substrate is heated with a first laser while the deposition gas is irradiated with a second laser to dissociate the deposition gas. 1 fig.

  14. Environmental Durability and Stress Rupture of EBC/CMCs

    NASA Technical Reports Server (NTRS)

    Appleby, Matthew; Morscher, Gregory N.; Zhu, Dongming

    2012-01-01

    This research focuses on the strength and creep performance of SiC fiber-reinforced SiC ceramic matrix composite (CMC) environmental barrier coating (EBC) systems under complex simulated engine environments. Tensile-strength and stress-rupture testing was conducted to illustrate the material properties under isothermal and thermal gradient conditions. To determine material durability, further testing was conducted under exposure to thermal cycling, thermal gradients and simulated combustion environments. Emphasis is placed on experimental techniques as well as implementation of non-destructive evaluation, including modal acoustic emission and electrical resistivity monitoring, to characterize strength degradation and damage mechanisms. Currently, little is known about the behavior of EBC-CMCs under these conditions; consequently, this work will prove invaluable in the development of structural components for use in high temperature applications.

  15. The durability of beneficial health effects associated with expressive writing.

    PubMed

    Sloan, Denise M; Feinstein, Brian A; Marx, Brian P

    2009-10-01

    This study examined the durability of benefits associated with expressive writing. Sixty-eight college undergraduates completed measures of physical and psychological health at the beginning of their first year and were then randomized to either an expressive writing or a control writing condition. Changes in physical health, psychological health (i.e., depression, stress, and anxiety), and academic performance were assessed two, four, and six months later. Findings indicated that participants assigned to the expressive writing condition reported less depression symptom severity at the two-month follow-up assessment relative to participants assigned to the control condition. However, these symptom reductions were not observed at any of the subsequent follow-up assessments. No significant changes were reported for physical health complaints, stress symptoms,anxiety symptoms, or academic performance. These findings suggest that,among first-year college students, expressive writing may provide some shortterm relief for certain symptoms.

  16. Durability investigation of a group of strain gage pressure transducers

    NASA Technical Reports Server (NTRS)

    Lederer, P. S.; Hilten, J. S.

    1972-01-01

    A durability investigation was conducted on a group of eighteen bonded-wire strain gage pressure transducers with ranges of 0 to 15 psig and 0 to 100 psig using an improved version of a previously developed technique. Some of the transducers were subjected to 40 million pressure cycles at a 5-Hz rate at laboratory ambient conditions, others were cycled at a temperature of 150 F (65.6 C). The largest change in sensitivity observed was 0.22% for a 100-psig transducer subjected to 40 million pressure cycles at 150 F. The largest change in zero pressure output observed was 0.91% FS for the same transducer. None of the transducers failed completely as a result of cycling at or below full scale pressure.

  17. Highly efficient and durable TiN nanofiber electrocatalyst supports

    NASA Astrophysics Data System (ADS)

    Kim, Hyun; Cho, Min Kyung; Kwon, Jeong An; Jeong, Yeon Hun; Lee, Kyung Jin; Kim, Na Young; Kim, Min Jung; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Nam, Suk Woo; Lim, Dong-Hee; Cho, Eunae; Lee, Kwan-Young; Kim, Jin Young

    2015-11-01

    To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via electrospinning and subsequent two-step thermal treatment processes as a support for the PEMFC catalyst. Pt catalyst nanoparticles (NPs) deposited on the TNFs (Pt/TNFs) were electrochemically characterized with respect to oxygen reduction reaction (ORR) activity and durability in an acidic medium. From the electrochemical tests, the TNF-supported Pt catalyst was better and more stable in terms of its catalytic performance compared to a commercially available carbon-supported Pt catalyst. For example, the initial oxygen reduction performance was comparable for both cases, while the Pt/TNF showed much higher durability from an accelerated degradation test (ADT) configuration. It is understood that the improved catalytic roles of TNFs on the supported Pt NPs for ORR are due to the high electrical conductivity arising from the extended connectivity, high inertness to the electrochemical environment and strong catalyst-support interactions.To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via

  18. Housing market capitalization of energy-saving durable good investments

    SciTech Connect

    Johnson, R.C.

    1981-07-01

    Rising energy prices provide an economic incentive to substitute capital for fuel in production processes, where the extent of substitution that is feasible is constrained by existing technologies. In the residential sector, such capital-fuel substitution depends upon the willingness of builders and homeowners to invest in the durable goods that make the house energy conserving. Since these durable goods become permanently attached to the dwelling unit and since ownership is likely to change over the lifetime of the house, the incentive to carry out an investment in energy conservation depends critically upon the efficiency of the housing market in capitalizing the financial benefits of future fuel savings. In this study of the Knoxville housing market during 1978, an hedonic price equation of the form P = f(U, X) was estimated, where P is the sale price of the house, U is the annual utility (fuel) bill, and X is a vector of structural, locational, and neighborhood attributes. The estimated hedonic price index reveals that, holding other influences constant, the marginal effect of a one-dollar savings in the annual fuel bill is to increase the sale price of the house by approximately $21. Estimates of implicit market discount rates, under various assumptions about fuel escalation rates and remaining lifetimes of the houses, indicate that the housing market performed in a manner consistent with a social discount rate of about 10 percent. The results of the study do not show whether or not investment in energy conservation is proceeding at a socially optimum rate, only that the housing market, in this location and period of time, did operate efficiently in capitalizing the investments.

  19. Moisture Durability Assessment of Selected Well-insulated Wall Assemblies

    SciTech Connect

    Pallin, Simon B.; Boudreaux, Philip R.; Kehrer, Manfred; Hun, Diana E.; Jackson, Roderick K.; Desjarlais, Andre Omer

    2015-12-01

    This report presents the results from studying the hygrothermal performance of two well-insulated wall assemblies, both complying with and exceeding international building codes (IECC 2015 2014, IRC 2015). The hygrothermal performance of walls is affected by a large number of influential parameters (e.g., outdoor and indoor climates, workmanship, material properties). This study was based on a probabilistic risk assessment in which a number of these influential parameters were simulated with their natural variability. The purpose of this approach was to generate simulation results based on laboratory chamber measurements that represent a variety of performances and thus better mimic realistic conditions. In total, laboratory measurements and 6,000 simulations were completed for five different US climate zones. A mold growth indicator (MGI) was used to estimate the risk of mold which potentially can cause moisture durability problems in the selected wall assemblies. Analyzing the possible impact on the indoor climate due to mold was not part of this study. The following conclusions can be reached from analyzing the simulation results. In a hot-humid climate, a higher R-value increases the importance of the airtightness because interior wall materials are at lower temperatures. In a cold climate, indoor humidity levels increase with increased airtightness. Air leakage must be considered in a hygrothermal risk assessment, since air efficiently brings moisture into buildings from either the interior or exterior environment. The sensitivity analysis of this study identifies mitigation strategies. Again, it is important to remark that MGI is an indicator of mold, not an indicator of indoor air quality and that mold is the most conservative indicator for moisture durability issues.

  20. Durability of bonds and clinical success of adhesive restorations

    PubMed Central

    Carvalho, Ricardo M.; Manso, Adriana P.; Geraldeli, Saulo; Tay, Franklin R.; Pashley, David H.

    2013-01-01

    Resin-dentin bond strength durability testing has been extensively used to evaluate the effectiveness of adhesive systems and the applicability of new strategies to improve that property. Clinical effectiveness is determined by the survival rates of restorations placed in non-carious cervical lesions (NCCL). While there is evidence that the bond strength data generated in laboratory studies somehow correlates with the clinical outcome of NCCL restorations, it is questionable whether the knowledge of bonding mechanisms obtained from laboratory testing can be used to justify clinical performance of resin-dentin bonds. There are significant morphological and structural differences between the bonding substrate used in in vitro testing versus the substrate encountered in NCCL. These differences qualify NCCL as a hostile substrate for bonding, yielding bond strengths that are usually lower than those obtained in normal dentin. However, clinical survival time of NCCL restorations often surpass the durability of normal dentin tested in the laboratory. Likewise, clinical reports on the long-term survival rates of posterior composite restorations defy the relatively rapid rate of degradation of adhesive interfaces reported in laboratory studies. This article critically analyzes how the effectiveness of adhesive systems is currently measured, to identify gaps in knowledge where new research could be encouraged. The morphological and chemical analysis of bonded interfaces of resin composite restorations in teeth that had been in clinical service for many years, but were extracted for periodontal reasons, could be a useful tool to observe the ultrastructural characteristics of restorations that are regarded as clinically acceptable. This could help determine how much degradation is acceptable for clinical success. PMID:22192252

  1. Fouling and long-term durability of an integrated forward osmosis and membrane distillation system.

    PubMed

    Husnain, T; Mi, B; Riffat, R

    2015-01-01

    An integrated forward osmosis (FO) and membrane distillation (MD) system has great potential for sustainable wastewater reuse. However, the fouling and long-term durability of the system remains largely unknown. This study investigates the fouling behaviour and efficiency of cleaning procedures of FO and MD membranes used for treating domestic wastewater. Results showed that a significant decline in flux of both FO and MD membranes were observed during treatment of wastewater with organic foulants. However, shear force generated by the increased cross-flow physically removed the loosely attached foulants from the FO membrane surface and resulted in 86-88% recovery of flux by cleaning with tap water. For the MD membrane, almost no flux recovery was achieved due to adsorption of organic foulants on the hydrophobic membrane surface, thus indicating significant irreversible fouling/wetting, which may not be effectively cleaned even with chemical reagents. Long-term (10 d) tests showed consistent performance of the FO membrane by rejecting the contaminants. However, organic foulants reduced the hydrophobicity of the MD membrane, caused wetting problems and allowed contaminants to pass through. The results demonstrate that combination of the FO and MD processes can effectively reduce irreversible membrane fouling and solve the wetting problem of the MD membrane. PMID:26606094

  2. Fouling and long-term durability of an integrated forward osmosis and membrane distillation system.

    PubMed

    Husnain, T; Mi, B; Riffat, R

    2015-01-01

    An integrated forward osmosis (FO) and membrane distillation (MD) system has great potential for sustainable wastewater reuse. However, the fouling and long-term durability of the system remains largely unknown. This study investigates the fouling behaviour and efficiency of cleaning procedures of FO and MD membranes used for treating domestic wastewater. Results showed that a significant decline in flux of both FO and MD membranes were observed during treatment of wastewater with organic foulants. However, shear force generated by the increased cross-flow physically removed the loosely attached foulants from the FO membrane surface and resulted in 86-88% recovery of flux by cleaning with tap water. For the MD membrane, almost no flux recovery was achieved due to adsorption of organic foulants on the hydrophobic membrane surface, thus indicating significant irreversible fouling/wetting, which may not be effectively cleaned even with chemical reagents. Long-term (10 d) tests showed consistent performance of the FO membrane by rejecting the contaminants. However, organic foulants reduced the hydrophobicity of the MD membrane, caused wetting problems and allowed contaminants to pass through. The results demonstrate that combination of the FO and MD processes can effectively reduce irreversible membrane fouling and solve the wetting problem of the MD membrane.

  3. Robust Damage-Mitigating Control of Aircraft for High Performance and Structural Durability

    NASA Technical Reports Server (NTRS)

    Caplin, Jeffrey; Ray, Asok; Joshi, Suresh M.

    1999-01-01

    This paper presents the concept and a design methodology for robust damage-mitigating control (DMC) of aircraft. The goal of DMC is to simultaneously achieve high performance and structural durability. The controller design procedure involves consideration of damage at critical points of the structure, as well as the performance requirements of the aircraft. An aeroelastic model of the wings has been formulated and is incorporated into a nonlinear rigid-body model of aircraft flight-dynamics. Robust damage-mitigating controllers are then designed using the H(infinity)-based structured singular value (mu) synthesis method based on a linearized model of the aircraft. In addition to penalizing the error between the ideal performance and the actual performance of the aircraft, frequency-dependent weights are placed on the strain amplitude at the root of each wing. Using each controller in turn, the control system is put through an identical sequence of maneuvers, and the resulting (varying amplitude cyclic) stress profiles are analyzed using a fatigue crack growth model that incorporates the effects of stress overload. Comparisons are made to determine the impact of different weights on the resulting fatigue crack damage in the wings. The results of simulation experiments show significant savings in fatigue life of the wings while retaining the dynamic performance of the aircraft.

  4. New finishing possibilities for producing durable multifunctional cotton/wool and viscose/wool blended fabrics.

    PubMed

    Ibrahim, N A; El-Zairy, M R; Eid, B M; El-Zairy, E M R; Emam, E M

    2015-03-30

    This research work focuses on the development of a one-bath functional finishing procedure for imparting durable multifunctional properties such as easy care, soft-hand, antibacterial and/or ultra violet (UV) protection to cotton/wool and viscose/wool blends using diverse finishing combinations and formulations. In this study finishing agents such as reactant resin, silicon softeners, 4-hydroxybenzophenone, triclosan, and pigment colorant were selected using magnesium chloride/citric acid as a mixed catalyst and the pad-dry microwave fixation technique. The results reveal that enhancement in the imparted functional properties are governed by type of the finished substrate as well as nature and concentration of finishing formulation components. The finished fabrics still retained high level of functionalities even after 15 consecutive laundering. Surface morphology and composition of selected samples were investigated using scan electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. The mode of interactions was also investigated. Practical applications for multifunctionlization of cellulose/wool blended fabrics are possible using these sorts of proper finishing formulations and unique finishing application method. PMID:25563959

  5. New finishing possibilities for producing durable multifunctional cotton/wool and viscose/wool blended fabrics.

    PubMed

    Ibrahim, N A; El-Zairy, M R; Eid, B M; El-Zairy, E M R; Emam, E M

    2015-03-30

    This research work focuses on the development of a one-bath functional finishing procedure for imparting durable multifunctional properties such as easy care, soft-hand, antibacterial and/or ultra violet (UV) protection to cotton/wool and viscose/wool blends using diverse finishing combinations and formulations. In this study finishing agents such as reactant resin, silicon softeners, 4-hydroxybenzophenone, triclosan, and pigment colorant were selected using magnesium chloride/citric acid as a mixed catalyst and the pad-dry microwave fixation technique. The results reveal that enhancement in the imparted functional properties are governed by type of the finished substrate as well as nature and concentration of finishing formulation components. The finished fabrics still retained high level of functionalities even after 15 consecutive laundering. Surface morphology and composition of selected samples were investigated using scan electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. The mode of interactions was also investigated. Practical applications for multifunctionlization of cellulose/wool blended fabrics are possible using these sorts of proper finishing formulations and unique finishing application method.

  6. Durability of crystalline phase in concrete microstructure modified by the mineral powders: evaluation by nanoindentation tests

    NASA Astrophysics Data System (ADS)

    Rajczakowska, Magdalena; Łydżba, Dariusz

    2016-03-01

    This paper presents the nanoindentation investigation of the evolution of concrete microstructure modified by the Internal Crystallization Technology mineral powders. The samples under study were retrieved from a fragment of a circular concrete lining of the vertical mine shaft at a depth of approximately 1,000 m. Due to the aggressive environment and exposure to contaminated water, the internal surface of the structure was deteriorated, decreasing its strength significantly. The mineral powders were applied directly on the surface lining. The specimens were investigated one month, three months and one year after the application of the aforementioned substance in order to verify the time dependence of the strengthening processes and durability of the crystalline phase. The microstructural changes of concrete were assessed with the use of nanoindentation technique. The testing procedure involved including the previously cut specimens in the epoxy resin and grinding and polishing in order to reduce the surface roughness. As a result of the nanoindentation tests the hardness as well as Young's modulus of the material were evaluated. The results were then compared and statistically analyzed. As a consequence, the disintegration time of the crystalline network in the pores of concrete was identified.

  7. The built heritage in the Southern Italy: problems of decay and significant properties of the building materials with relation to their durability and conservationDECAY AND SIGNIFICANT PROPERTIES OF THE BUILDING MATERIALS WITH RELATION TO THEIR DURABILITY

    NASA Astrophysics Data System (ADS)

    Sileo, M.; Calia, A.

    2012-04-01

    This paper deals with the use of building materials within the built heritage of the Southern Italy, their decay problems and the research of stone parameters material to their durability. The study documents the most common and widespread stone building materials and their forms of decay within the historical-architectural heritage, as well as in the archaeological artifacts. The heavy presence of the decay forms related to granular disgregation and loss of powder material from the surface suggest an high susceptibility of such materials to the disruptive processes induced by water penetration and salt crystallisation. The study of the stone properties and artificial ageing tests in laboratory, carried out by comparing several lithologies, are aimed to understand their response to the decay with relation to the petrophisical and compositional features, with the final purpose to identify durability parameters, usefull for choosing the appropriate conservation measures. In order to this final purpose, further elements of evaluation are drawn by the activity in progress, concerning the monitoring of the conservation treatments carried out on the Baroque heritage of Lecce town (Southern Italy) during the last decades.

  8. Long-term efficacy, safety and durability of Juvéderm® XC.

    PubMed

    Ballin, Annelyse C; Cazzaniga, Alex; Brandt, Fredric S

    2013-01-01

    Over the last decade, there has been increasing interest in minimally invasive cosmetic treatments, especially for facial rejuvenation. Next to botulinum toxin injection, the injection of soft tissue fillers is the second most frequent minimally invasive procedure performed in the USA. Hyaluronic acid (HA) is the most commonly used dermal filler. One of patients' main concerns about filler injections pertains to pain and discomfort. Topical anesthetics, nerve blocks, and/or the incorporation of lidocaine to the filler have been applied in order to reduce distress and pain. Despite nerve blocks being an effective form of anesthesia, they may distort the area to be treated, as well as lengthen and complicate the procedure. Studies have shown that the incorporation of lidocaine to HA fillers significantly reduces pain and discomfort. Yet, one of the dilemmas about the addition of lidocaine solution to HA fillers is the possible alteration of the physical characteristics of the product by negatively impacting the efficacy and/or duration of the filler. The concern is that the addition of lidocaine could dilute the product, creating less correction per mL, changing the product's viscosity and consequently the "lifting" ability. Also, this dilution could reduce the product's duration. There may be a difference between a physician adding an aqueous solution into a lidocaine-free version of HA and the pre-incorporated lidocaine version of HA. An aqueous solution might dilute the product, while the pre-incorporated powder lidocaine appears to avoid this problem. Juvéderm® XC is manufactured with powder lidocaine 0.3%; it is associated with significantly less injection pain than Juvéderm® and other lidocaine-free versions of HA. Studies have shown that lidocaine enhances treatment comfort and optimizes the injection experience while maintaining a similar safety and effectiveness profile. Regarding the longevity, further study is necessary to determine if there is any

  9. Unanticipated Effects of New Drug Availability on Antiretroviral Durability: Implications for Comparative Effectiveness Research

    PubMed Central

    Eaton, Ellen F.; Tamhane, Ashutosh R.; Burkholder, Greer A.; Willig, James H.; Saag, Michael S.; Mugavero, Michael J.

    2016-01-01

    Background. Durability of antiretroviral (ARV) therapy is associated with improved human immunodeficiency virus (HIV) outcomes. Data on ARV regimen durability in recent years and clinical settings are lacking. Methods. This retrospective follow-up study included treatment-naive HIV-infected patients initiating ARV therapy between January 2007 and December 2012 in a university-affiliated HIV clinic in the Southeastern United States. Outcome of interest was durability (time to discontinuation) of the initial regimen. Durability was evaluated using Kaplan-Meier survival analyses. Cox proportional hazard analyses was used to evaluate the association among durability and sociodemographic, clinical, and regimen-level factors. Results. Overall, 546 patients were analyzed. Median durability of all regimens was 39.5 months (95% confidence interval, 34.1–44.4). Commonly prescribed regimens were emtricitabine and tenofovir with efavirenz (51%; median duration = 40.1 months) and with raltegravir (14%; 47.8 months). Overall, 67% of patients had an undetectable viral load at the time of regimen cessation. Discontinuation was less likely with an integrase strand transfer inhibitor (adjusted hazards ratio [aHR] = 0.35, P = .001) or protease inhibitor-based regimen (aHR = 0.45, P = .006) and more likely with a higher pill burden (aHR = 2.25, P = .003) and a later treatment era (aHR = 1.64, P < .001). Conclusions. Initial ARV regimen longevity declined in recent years contemporaneous with the availability of several new ARV drugs and combinations. Reduced durability mostly results from a preference for newly approved regimens rather than indicating failing therapy, as indicated by viral suppression observed in a majority of patients (67%) prior to regimen cessation. Durability is influenced by extrinsic factors including new drug availability and provider preference. Medication durability must be interpreted carefully in the context of a dynamic treatment landscape. PMID

  10. Durability of Polymeric Encapsulation Materials for a PMMA/glass Concentrator Photovoltaic System

    SciTech Connect

    Miller, David C.; Kempe, Michael D.; Muller, Matthew T; Gray, Matthew H.; Araki, Kenji; Kurtz, Sarah R.

    2014-04-08

    The durability of polymeric encapsulation materials was examined using outdoor exposure at the nominal geometric concentration of 500 suns. The results for 36 months cumulative field deployment are presented for materials including: poly(ethylene-co-vinyl acetate), (EVA); polyvinyl butyral (PVB); ionomer; polyethylene/ polyoctene copolymer (PO); thermoplastic polyurethane (TPU); poly(dimethylsiloxane) (PDMS); poly(diphenyl dimethyl siloxane) (PDPDMS); and poly(phenyl-methyl siloxane) (PPMS). Measurements of the field conditions including ambient temperature and ultraviolet (UV) dose were recorded at the test site during the experiment. Measurements for the experiment included optical transmittance (with subsequent analysis of solar-weighted transmittance, UV cut-off wavelength, and yellowness index), mass, visual photography, photoelastic imaging, and fluorescence spectroscopy. While the results to date for EVA are presented and discussed, examination here focuses more on the siloxane materials. A specimen recently observed to fail by thermal decomposition is discussed in terms of the implementation of the experiment as well as its fluorescence signature, which was observed to become more pronounced with age. Modulated thermogravimetry (allowing determination of the activation energy of thermal decomposition) was performed on a subset of the siloxanes to quantify the propensity for decomposition at elevated temperatures. Supplemental, Pt-catalyst- and primer-solutions as well as peroxide-cured PDMS specimens were examined to assess the source of the luminescence. The results of the study including the change in optical transmittance, observed failure modes, and subsequent analyses of the failure modes are described in the conclusions.

  11. Durability of the bond between bone and various 2-cyanoacrylates in an aqueous environment.

    PubMed

    Brauer, G M; Kumpula, J W; Termini, D J; Davidson, K M

    1979-07-01

    The durability of the bond strength developed between 2-cyanoacrylate esters and bone has been determined by aging specimens in water. One-day bond strength of the isobutyl and isomeric amyl 2-cyanoacrylates varied from 6.2 to 7.2 MPa. The strength of the bond decreased on storage or on thermocycling in water. Hydrolytic stability increased with increasing length of the alkyl ester group. After a six-month storage in water the various amyl 2-cyanoacrylates retained from 70% to 73% of their one-day bond strength. Pretreatment of the bone surface prior to application of the adhesive did not prove beneficial. The cured 2-cyanoacrylate can be removed from the substrate surface by appropriate solvents. Thus, it is not bonded covalently to bone. The bond strength, especially of the isobutyl and amyl 2-cyanoacrylates to bone in an aqueous environment, appears to be superior to other adhesives. Provided these monomers are biocompatible, they may be useful clinically where an intermediate-term adhesion is desired.

  12. Atomic Oxygen Durability of Second Surface Silver Microsheet Glass Concentrators

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Jaworske, Donald A.; Smith, Daniela C.; Mroz, Thaddeus S.

    1996-01-01

    Second surface silver microsheet glass concentrators are being developed for potential use in future solar dynamic space power systems. Traditional concentrators are aluminum honeycomb sandwich composites with either aluminum or graphite epoxy face sheets, where a reflective aluminum layer is deposited onto an organic leveling layer on the face sheet. To protect the underlying layers, a SiO2 layer is applied on top of the aluminum reflective layer. These concentrators may be vulnerable to atomic oxygen degradation due to possible atomic oxygen attack of the organic layers at defect sites in the protective and reflective coatings. A second surface microsheet glass concentrator would be inherently more atomic oxygen durable than these first surface concentrators. In addition, a second surface microsheet glass concentrator design provides a smooth optical surface and allows for silver to be used as a reflective layer, which would improve the reflectivity of the concentrator and the performance of the system. A potential threat to the performance of second surface microsheet glass concentrators is atomic oxygen attack of the underlying silver at seams and edges or at micrometeoroid and debris (MMD) impacts sites. Second surface silver microsheet glass concentrator samples were fabricated and tested for atomic oxygen durability. The samples were iteratively exposed to an atomic oxygen environment in a plasma asher. Samples were evaluated for potential degradation at fabrication seams, simulated MMD impact sites, and edges. Optical microscopy was used to evaluate atomic oxygen degradation. Reflectance was obtained for an impacted sample prior to and after atomic oxygen exposure. After an initial atomic oxygen exposure to an effective fluence of approx. 1 x 10(exp 21) atoms/cm(exp 2), oxidation of the silver at defect sites and edges was observed. Exposure to an additional approx. 1 x 10(exp 21) atoms/cm(exp 2) caused no observed increase in oxidation. Oxidation at an

  13. Flexible, Mechanically Durable Aerogel Composites for Oil Capture and Recovery.

    PubMed

    Karatum, Osman; Steiner, Stephen A; Griffin, Justin S; Shi, Wenbo; Plata, Desiree L

    2016-01-13

    More than 30 years separate the two largest oil spills in North American history (the Ixtoc I and Macondo well blowouts), yet the responses to both disasters were nearly identical in spite of advanced material innovation during the same time period. Novel, mechanically durable sorbents could enable (a) sorbent use in the open ocean, (b) automated deployment to minimize workforce exposure to toxic chemicals, and (c) mechanical recovery of spilled oils. Here, we explore the use of two mechanically durable, low-density (0.1-0.2 g cm(-3)), highly porous (85-99% porosity), hydrophobic (water contact angles >120°), flexible aerogel composite blankets as sorbent materials for automated oil capture and recovery: Cabot Thermal Wrap (TW) and Aspen Aerogels Spaceloft (SL). Uptake of crude oils (Iraq and Sweet Bryan Mound oils) was 8.0 ± 0.1 and 6.5 ± 0.3 g g(-1) for SL and 14.0 ± 0.1 and 12.2 ± 0.1 g g(-1) for TW, respectively, nearly twice as high as similar polyurethane- and polypropylene-based devices. Compound-specific uptake experiments and discrimination against water uptake suggested an adsorption-influenced sorption mechanism. Consistent with that mechanism, chemical extraction oil recoveries were 95 ± 2 (SL) and 90 ± 2% (TW), but this is an undesirable extraction route in decentralized oil cleanup efforts. In contrast, mechanical extraction routes are favorable, and a modest compression force (38 N) yielded 44.7 ± 0.5% initially to 42.0 ± 0.4% over 10 reuse cycles for SL and initially 55.0 ± 0.1% for TW, degrading to 30.0 ± 0.2% by the end of 10 cycles. The mechanical integrity of SL deteriorated substantially (800 ± 200 to 80 ± 30 kPa), whereas TW was more robust (380 ± 80 to 700 ± 100 kPa) over 10 uptake-and-compression extraction cycles.

  14. Flexible, Mechanically Durable Aerogel Composites for Oil Capture and Recovery.

    PubMed

    Karatum, Osman; Steiner, Stephen A; Griffin, Justin S; Shi, Wenbo; Plata, Desiree L

    2016-01-13

    More than 30 years separate the two largest oil spills in North American history (the Ixtoc I and Macondo well blowouts), yet the responses to both disasters were nearly identical in spite of advanced material innovation during the same time period. Novel, mechanically durable sorbents could enable (a) sorbent use in the open ocean, (b) automated deployment to minimize workforce exposure to toxic chemicals, and (c) mechanical recovery of spilled oils. Here, we explore the use of two mechanically durable, low-density (0.1-0.2 g cm(-3)), highly porous (85-99% porosity), hydrophobic (water contact angles >120°), flexible aerogel composite blankets as sorbent materials for automated oil capture and recovery: Cabot Thermal Wrap (TW) and Aspen Aerogels Spaceloft (SL). Uptake of crude oils (Iraq and Sweet Bryan Mound oils) was 8.0 ± 0.1 and 6.5 ± 0.3 g g(-1) for SL and 14.0 ± 0.1 and 12.2 ± 0.1 g g(-1) for TW, respectively, nearly twice as high as similar polyurethane- and polypropylene-based devices. Compound-specific uptake experiments and discrimination against water uptake suggested an adsorption-influenced sorption mechanism. Consistent with that mechanism, chemical extraction oil recoveries were 95 ± 2 (SL) and 90 ± 2% (TW), but this is an undesirable extraction route in decentralized oil cleanup efforts. In contrast, mechanical extraction routes are favorable, and a modest compression force (38 N) yielded 44.7 ± 0.5% initially to 42.0 ± 0.4% over 10 reuse cycles for SL and initially 55.0 ± 0.1% for TW, degrading to 30.0 ± 0.2% by the end of 10 cycles. The mechanical integrity of SL deteriorated substantially (800 ± 200 to 80 ± 30 kPa), whereas TW was more robust (380 ± 80 to 700 ± 100 kPa) over 10 uptake-and-compression extraction cycles. PMID:26701744

  15. Durability and performance optimization of cathode materials for fuel cells

    NASA Astrophysics Data System (ADS)

    Colon-Mercado, Hector Rafael

    The primary objective of this dissertation is to develop an accelerated durability test (ADT) for the evaluation of cathode materials for fuel cells. The work has been divided in two main categories, namely high temperature fuel cells with emphasis on the Molten Carbonate Fuel Cell (MCFC) cathode current collector corrosion problems and low temperature fuel cells in particular Polymer Electrolyte Fuel Cell (PEMFC) cathode catalyst corrosion. The high operating temperature of MCFC has given it benefits over other fuel cells. These include higher efficiencies (>50%), faster electrode kinetics, etc. At 650°C, the theoretical open circuit voltage is established, providing low electrode overpotentials without requiring any noble metal catalysts and permitting high electrochemical efficiency. The waste heat is generated at sufficiently high temperatures to make it useful as a co-product. However, in order to commercialize the MCFC, a lifetime of 40,000 hours of operation must be achieved. The major limiting factor in the MCFC is the corrosion of cathode materials, which include cathode electrode and cathode current collector. In the first part of this dissertation the corrosion characteristics of bare, heat-treated and cobalt coated titanium alloys were studied using an ADT and compared with that of state of the art current collector material, SS 316. PEMFCs are the best choice for a wide range of portable, stationary and automotive applications because of their high power density and relatively low-temperature operation. However, a major impediment in the commercialization of the fuel cell technology is the cost involved due to the large amount of platinum electrocatalyst used in the cathode catalyst. In an effort to increase the power and decrease the cathode cost in polymer electrolyte fuel cell (PEMFC) systems, Pt-alloy catalysts were developed to increase its activity and stability. Extensive research has been conducted in the area of new alloy development and

  16. Preparation, structure, and in vitro chemical durability of yttrium phosphate microspheres for intra-arterial radiotherapy.

    PubMed

    Kawashita, Masakazu; Matsui, Naoko; Li, Zhixia; Miyazaki, Toshiki; Kanetaka, Hiroyasu

    2011-10-01

    Chemically durable microspheres containing yttrium and/or phosphorus are useful for intra-arterial radiotherapy. In this study, we attempted to prepare yttrium phosphate (YPO₄) microspheres with high chemical durability. YPO₄ microspheres with smooth surfaces and diameters of around 25 μm were successfully obtained when gelatin droplets containing yttrium and phosphate ions were cooled and solidified in a water-in-oil emulsion and then heat-treated at 1100°C. The chemical durability of the heat-treated microspheres in a simulated body fluid at pH = 6 and 7 was high enough for clinical application of intra-arterial radiotherapy.

  17. Structural Analyses of Stirling Power Convertor Heater Head for Long-Term Reliability, Durability, and Performance

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Shah, Ashwin; Arya, Vinod K.; Krause, David L.; Bartolotta, Paul A.

    2002-01-01

    Deep-space missions require onboard electric power systems with reliable design lifetimes of up to 10 yr and beyond. A high-efficiency Stirling radioisotope power system is a likely candidate for future deep-space missions and Mars rover applications. To ensure ample durability, the structurally critical heater head of the Stirling power convertor has undergone extensive computational analyses of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Durability predictions are presented in terms of the probability of survival. A benchmark structural testing program has commenced to support the analyses. This report presents the current status of durability assessments.

  18. Preparation of durable hydrophobic cellulose fabric from water glass and mixed organosilanes

    NASA Astrophysics Data System (ADS)

    Shang, Song-Min; Li, Zhengxiong; Xing, Yanjun; Xin, John H.; Tao, Xiao-Ming

    2010-12-01

    Durable superhydrophobic cellulose fabric was prepared from water glass and n-octadecyltriethoxysilane (ODTES) with 3-glycidyloxypropyltrimethoxysilane (GPTMS) as crosslinker by sol-gel method. The result showed that the addition of GPTMS could result in a better fixation of silica coating from water glass on cellulose fabric. The silanization of hydrolyzed ODTES at different temperatures and times was studied and optimized. The results showed that silanization time was more important than temperature in forming durable hydrophobic surface. The durability of superhydrophobicity treatment was analyzed by XPS. As a result, the superhydrophobic cotton treated under the optimal condition still remained hydrophobic properties after 50 washing cycles.

  19. Gestational age

    MedlinePlus

    Fetal age - gestational age; Gestation; Neonatal gestational age; Newborn gestational age ... Gestational age can be determined before or after birth. Before birth, your health care provider will use ultrasound to ...

  20. Durable zinc ferrite sorbent pellets for hot coal gas desulfurization

    SciTech Connect

    Jha, M.C.; Blandon, A.E.; Hepworth, M.T.

    1988-03-22

    A durable, pelletized and indurated sorbent for removing hydrogen sulfide from hot coal gas is described which consists essentially of zinc ferrite, has a surface area of about 0.5 to about 5 m./sup 2/gram, and is prepared by mixing fine iron oxide and fine zinc oxide, each having a particle size of less than about 1 micron in substantially equi-molar amounts with an inorganic binder in an amount greater than zero and up to about 15%, by weight, and an organic binder in an amount greater than zero and up to about 5%, by weight, up to about 5%, by weight, of manganese oxide, up to about 0.2%, by weight, of an alkali metal carbonate and up to about 0.2%, by weight, of molybdenite. The inorganic binder is capable of a strong bridging action between zinc ferrite particles during induration and the organic binder is capable of burning away during induration to form a porous structure, pelletizing the resulting mixture with water, drying the resulting pellets and indurating the dried pellets and a temperature of about 1600/sup 0/F to about 2000/sup 0/F to form strong, porous sorbent pellets having a crush strength of about 5 to about 20 lbs. Dead Weight Load.

  1. RDS-21 Face-Gear Surface Durability Tests

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Heath, Gregory F.; Filler, Robert R.; Slaughter, Stephen C.; Fetty, Jason

    2007-01-01

    Experimental fatigue tests were performed to determine the surface durability life of a face gear in mesh with a tapered spur involute pinion. Twenty-four sets of gears were tested at three load levels: 7200, 8185, and 9075 lb-in face gear torque, and 2190 to 3280 rpm face gear speed. The gears were carburized and ground, shot-peened and vibro-honed, and made from VIM-VAR Pyrowear 53 steel per AMS 6308. The tests produced 17 gear tooth spalling failures and 7 suspensions. For all the failed sets, spalling occurred on at least one tooth of all the pinions. In some cases, the spalling initiated a crack in the pinion teeth which progressed to tooth fracture. Also, spalling occurred on some face gear teeth. The AGMA endurance allowable stress for a tapered spur involute pinion in mesh with a face gear was determined to be 275 ksi for the material tested. For the application of a tapered spur involute pinion in mesh with a face gear, proper face gear shim controlled the desired gear tooth contact pattern while proper pinion shim was an effective way of adjusting backlash without severely affecting the contact pattern.

  2. Transparent superwetting nanofilms with enhanced durability at model physiological condition

    NASA Astrophysics Data System (ADS)

    Hwangbo, Sunghee; Heo, Jiwoong; Lin, Xiangde; Choi, Moonhyun; Hong, Jinkee

    2016-01-01

    There have been many studies on superwetting surfaces owing to the variety of their potential applications. There are some drawbacks to developing these films for biomedical applications, such as the fragility of the microscopic roughness feature that is vital to ensure superwettability. But, there are still only a few studies that have shown an enhanced durability of nanoscale superwetting films at certain extreme environment. In this study, we fabricated intrinsically stable superwetting films using the organosilicate based layer-by-layer (LbL) self-assembly method in order to control nano-sized roughness of the multilayer structures. In order to develop mechanically and chemically robust surfaces, we successfully introduced polymeric silsesquioxane as a building block for LbL assembly with desired fashion. Even in the case that the superhydrophobic outer layers were damaged, the films maintained their superhydrophobicity because of the hydrophobic nature of their inner layers. As a result, we successfully fabricated superwetting nano-films and evaluated their robustness and stability.

  3. Electro-active paper for a durable biomimetic actuator

    NASA Astrophysics Data System (ADS)

    Yun, Sung-Ryul; Yun, Gyu Young; Kim, Jung Hwan; Chen, Yi; Kim, Jaehwan

    2009-02-01

    Cellulose electro-active paper (EAPap), known as a smart material, has merits in terms of low voltage operation, light weight, dryness, low power consumption, biodegradability, abundance and low price. Since EAPap requires low power consumption, a remotely driven actuator has been proposed using microwave power transmission. This concept is attractive for many biomimetic systems such as crawling micro-insect robots, flying objects like dragon flies and smart wallpapers. However, the actuation performance of EAPap is sensitive to humidity and degrades with time. Thus, in this paper, a durable EAPap is studied. The fabrication of EAPap is explained and the actuation performance is shown with applied electric field, frequency, humidity level and time. The fabrication process includes dissolving cellulose fibers, eliminating solvent and Li ions with a mixture of deionized water and isopropyl alcohol, washing with water, drying and coating with gold. The morphology of the fabricated EAPap is analyzed by taking scanning electron microscope images and x-ray diffractograms. The actuation performance is tested in terms of bending displacement with frequency, time and humidity level

  4. New concept in durability improvement of hip total joint endoprostheses.

    PubMed

    Capitanu, Lucian; Florescu, Virgil; Badita, Liliana-Laura

    2014-01-01

    Starting from the well-known fact that the rolling movement always has a lower friction compared to sliding friction, the authors have conceived and realized a pivoting movement joint on a "layer of balls" with "compensation space", placed between the acetabular cup and the femoral head. This technical solution allows free self-directed migration of the balls, depending on the resistance opposed, with successive occupation of the "compensation space". As a concept, the proposed technical solution excludes the existence of a cage for maintaining the relative positions of the spheres. It can be observed that the smallest values of the force and of the friction coefficient are obtained for the prostheses with balls and self-directed movement (approximately 5 times smaller than the values obtained for a classical prosthesis). For all the couples tested, the friction force grows with the growth of the normal load and of the oscillation speed. Changing the contact mechanism for the artificial hip joint from one sliding contact between two large surfaces, to a multitude of rolling contacts, could lead to some problems regarding functionality and durability of the active prosthesis elements. The key to an accurate evaluation of damaging mechanisms acting on THP with self directed rolling balls is a clear and complete picture of the load transfer mechanism.

  5. Durability of recycled aggregate concrete using pozzolanic materials.

    PubMed

    Ann, K Y; Moon, H Y; Kim, Y B; Ryou, J

    2008-01-01

    In this study, pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS) were used to compensate for the loss of strength and durability of concrete containing recycled aggregate. As a result, 30% PFA and 65% GGBS concretes increased the compressive strength to the level of control specimens cast with natural granite gravel, but the tensile strength was still lowered at 28 days. Replacement with PFA and GGBS was effective in raising the resistance to chloride ion penetrability into the concrete body, measured by a rapid chloride ion penetration test based on ASTM C 1202-91. It was found that the corrosion rate of 30% PFA and 65% GGBS concretes was kept at a lower level after corrosion initiation, compared to the control specimens, presumably due to the restriction of oxygen and water access. However, it was less effective in increasing the chloride threshold level for steel corrosion. Hence, it is expected that the corrosion time for 30% PFA and 65% GGBS concrete containing recycled aggregate mostly equates to the corrosion-free life of control specimens.

  6. Polyaniline: a conductive polymer coating for durable nanospray emitters

    PubMed

    Maziarz; Lorenz; White; Wood

    2000-07-01

    Despite the tremendous sensitivity and lower sample requirements for nanospray vs. conventional electrospray, metallized nanospray emitters have suffered from one of two problems: low mechanical stability (leading to emitter failure) or lengthy, tedious production methods. Here, we describe a simple alternative to metallized tips using polyaniline (PANI), a synthetic polymer well known for its high conductivity, anticorrosion properties, antistatic properties, and mechanical stability. A simple method for coating borosilicate emitters (1.2 mm o.d.) pulled to fine tapers (4 +/- 1 microm) with water-soluble and xylene-soluble dispersions of conductive polyaniline (which allows for electrical contact at the emitter outlet) is described. The polyaniline-coated emitters show high durability and are resistant to electrical discharge, likely because of the thick (yet optically transparent) coatings; a single emitter can be used over a period of days for multiple samples with no visible indication of the destruction of the polyaniline coating. The optical transparency of the coating also allows the user to visualize the sample plug loaded into the emitter. Examples of nanospray using coatings of the water-soluble and xylene-soluble polyaniline dispersions are given. A comparison of PANI-coated and gold-coated nanospray emitters to conventional electrospray ionization (ESI) show that PANI-coated emitters provide similar enhanced sensitivity that gold-coated emitters exhibit vs. conventional ESI.

  7. Durable pd-based alloy and hydrogen generation membrane thereof

    DOEpatents

    Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

    2010-02-02

    A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

  8. New MEA Materials for Improved DMFC Performance, Durability and Cost

    SciTech Connect

    Fletcher, James H.; Campbell, Joseph L.; Cox, Philip; Harrington, William J.

    2013-09-16

    Abstract Project Title: New MEA Materials for Improved DMFC Performance, Durability and Cost The University of North Florida (UNF)--with project partners the University of Florida, Northeastern University, and Johnson Matthey--has recently completed the Department of Energy (DOE) project entitled “New MEA Materials for Improved DMFC Performance, Durability and Cost”. The primary objective of the project was to advance portable fuel cell MEA technology towards the commercial targets as laid out in the DOE R&D roadmap by developing a passive water recovery MEA (membrane electrode assembly). Developers at the University of North Florida identified water management components as an insurmountable barrier to achieving the required system size and weight necessary to achieve the energy density requirements of small portable power applications. UNF developed an innovative “passive water recovery” MEA for direct methanol fuel cells (DMFC) which provides a path to system simplification and optimization. The passive water recovery MEA incorporates a hydrophobic, porous, barrier layer within the cathode electrode, so that capillary pressure forces the water produced at the cathode through holes in the membrane and back to the anode. By directly transferring the water from the cathode to the anode, the balance of plant is very much simplified and the need for heavy, bulky water recovery components is eliminated. At the heart of the passive water recovery MEA is the UNF DM-1 membrane that utilizes a hydrocarbon structure to optimize performance in a DMFC system. The membrane has inherent performance advantages, such as a low methanol crossover (high overall efficiency), while maintaining a high proton conductivity (good electrochemical efficiency) when compared to perfluorinated sulfonic acid membranes such as Nafion. Critically, the membrane provides an extremely low electro-osmotic drag coefficient of approximately one water molecule per proton (versus the 2-3 for

  9. Durability tests of a fiber optic corrosion sensor.

    PubMed

    Wan, Kai Tai; Leung, Christopher K Y

    2012-01-01

    Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively. PMID:22737030

  10. Durability of Intercalated Graphite Epoxy Composites in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Davidson, Michelle L.; Shively, Rhonda

    1996-01-01

    The electrical conductivity of graphite epoxy composites can be substantially increased by intercalating (inserting guest atoms or molecules between the graphene planes) the graphite fibers before composite formation. The resulting high strength, low density, electrically conducting composites have been proposed for EMI shielding in spacecraft. Questions have been raised, however, about their durability in the space environment, especially with respect to outgassing of the intercalates, which are corrosive species such as bromine. To answer those concerns, six samples of bromine intercalated graphite epoxy composites were included in the third Evaluation of Oxygen Interaction with Materials (EOIM-3) experiment flown on the Space Shuttle Discovery (STS-46). Changes in electrical conductivity, optical reflectance, surface texture, and mass loss for SiO2 protected and unprotected samples were measured after being exposed to the LEO environment for 42 hours. SiO2 protected samples showed no degradation, verifying conventional protection strategies are applicable to bromine intercalated composites. The unprotected samples showed that bromine intercalation does not alter the degradation of graphite-epoxy composites. No bromine was detected to have been released by the fibers allaying fears that outgassing could be disruptive to the sensitive electronics the EMI shield is meant to protect.

  11. Durability of Polymeric Encapsulation Materials for Concentrating Photovoltaic Systems (Presentation)

    SciTech Connect

    Miller, D. C.; Muller, M.; Kempe, M. D.; Araki, K.; Kennedy, C. E.; Kurtz, S. R.

    2012-03-01

    Many concentrating photovoltaic (CPV) systems use a polymeric encapsulant to couple and optical component and/or coverglass to the cell. In that location, the encapsulation improves the transmission of concentrated optical flux through interface(s), while protecting the cell from the environment. The durability of encapsulation materials, however, is not well established relative to the desired service life of 30 years. Therefore, we have initiated a screen test to identify the field-induced failure modes for a variety of popular PV encapsulation materials. An existing CPV module (with no PV cells present) was modified to accommodate encapsulation specimens. The module (where nominal concentration of solar flux is 500x for the domed-Fresnel design) has been mounted on a tracker in Golden, CO (elevation 1.79 km). Initial results are reported here for 18 months cumulative exposure, including the hottest and coldest months of the past year. Characteristics observed at intervals during that time include: visual appearance, direct and hemispherical transmittance, and mass. Degradation may be assessed from subsequent analysis (including yellowness index and cut-on frequency) relative to the ambient conditions present during field exposure. The fluorescence signature observed of all the silicone specimens is examined here, including possible factors of causation -- the platinum catalyst used in the addition cured materials as well as the primer used to promote adhesion to the quartz substrate and superstrate.

  12. Durability Tests of a Fiber Optic Corrosion Sensor

    PubMed Central

    Wan, Kai Tai; Leung, Christopher K.Y.

    2012-01-01

    Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively. PMID:22737030

  13. Durability and Damage Tolerance of High Temperature Polymeric Composites

    NASA Technical Reports Server (NTRS)

    Case, Scott W.; Reifsnider, Kenneth L.

    1996-01-01

    Modern durability and damage tolerance predictions for composite material systems rely on accurate estimates of the local stress and material states for each of the constituents, as well as the manner in which the constituents interact. In this work, an number of approaches to estimating the stress states and interactions are developed. First, an elasticity solution is presented for the problem of a penny-shaped crack in an N-phase composite material system opened by a prescribed normal pressure. The stress state around such a crack is then used to estimate the stress concentrations due to adjacent fiber fractures in composite materials. The resulting stress concentrations are then used to estimate the tensile strength of the composite. The predicted results are compared with experimental values. In addition, a cumulative damage model for fatigue is presented. Modifications to the model are made to include the effects of variable amplitude loading. These modifications are based upon the use of remaining strength as a damage metric and the definition of an equivalent generalized time. The model is initially validated using results from the literature. Also, experimental data from APC-2 laminates and IM7/K3B laminates are used in the model. The use of such data for notched laminates requires the use of an effective hole size, which is calculated based upon strain distribution measurements. Measured remaining strengths after fatigue loading are compared with the predicted values for specimens fatigued at room temperature and 350 F (177 C).

  14. Durability of the accretion disk of millisecond pulsars.

    PubMed

    Michel, F C; Dessler, A J

    1985-05-24

    Pulsars with pulsation periods in the millisecond range are thought to be neutron stars that have acquired an extraordinarily short spin period through the accretion of stellar material spiraling down onto the neutron star from a nearby companion. Nearly all the angular momentum and most of the mass of the companion star is transferred to the neutron star. During this process, wherein the neutron star consumes its companion, it is required that a disk of stellar material be formed around the neutron star. In conventional models it is supposed that the disk is somehow lost when the accretion phase is finished, so that only the rapidly spinning neutron star remains. However, it is possible that, after the accretion phase, a residual disk remains in stable orbit around the neutron star. The end result of such an accretion process is an object that looks much like a miniature (about 100 kilometers), heavy version of Saturn: a central object (the neutron star) surrounded by a durable disk. PMID:17797665

  15. Space environment durability of beta cloth in LDEF thermal blankets

    NASA Technical Reports Server (NTRS)

    Linton, Roger C.; Whitaker, Ann F.; Finckenor, Miria M.

    1993-01-01

    Beta cloth performance for use on long-term space vehicles such as Space Station Freedom (S.S. Freedom) requires resistance to the degrading effects of the space environment. The major issues are retention of thermal insulating properties through maintaining optical properties, preserving mechanical integrity, and generating minimal particulates for contamination-sensitive spacecraft surfaces and payloads. The longest in-flight test of beta cloth's durability was on the Long Duration Exposure Facility (LDEF), where it was exposed to the space environment for 68 months. The LDEF contained 57 experiments which further defined the space environment and its effects on spacecraft materials. It was deployed into low-Earth orbit (LEO) in Apr. 1984 and retrieved Jan. 1990 by the space shuttle. Among the 10,000 plus material constituents and samples onboard were thermal control blankets of multilayer insulation with a beta cloth outer cover and Velcro attachments. These blankets were exposed to hard vacuum, thermal cycling, charged particles, meteoroid/debris impacts, ultraviolet (UV) radiation, and atomic oxygen (AO). Of these space environmental exposure elements, AO appears to have had the greatest effect on the beta cloth. The beta cloth analyzed in this report came from the MSFC Experiment S1005 (Transverse Flat-Plate Heat Pipe) tray oriented approximately 22 deg from the leading edge vector of the LDEF satellite. The location of the tray on LDEF and the placement of the beta cloth thermal blankets are shown. The specific space environment exposure conditions for this material are listed.

  16. Superhydrophobic durable coating based on UV-photoreactive silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Nahum, T.; Dodiuk, H.; Dotan, A.; Kenig, S.; Lellouche, J. P.

    2015-05-01

    Superhydrophobic surfaces with contact angle (CA) >150 and sliding angle (SA) <10 have been aroused curiosity over the years due to their various applications. Superhydrophobicity can be obtained tailoring the chemistry and the roughness of the surface, mimicking the Lotus flower. Most superhydrophobic surfaces based on secondary bonding lose their roughness in harsh conditions and are unsuitable for practical applications. Photoreactive SiO2 nanoparticles (NPs) based on benzophenone (BP) can be a very effective tool for formation of reactive species that function as a molecular bridge by covalent bonding between the NP and any polymer matrix with C-C and C-H bonds. The present work focused on thermoset radiation curing urethane acrylate. Upon UV irradiation reactive excited nπ* triplet benzophenone species are formed and react through hydrogen abstraction to form ketyl radicals which interact with a radicals from the UV irradiated polymer matrix to yield covalent bonding. Roughness was achieved by dipping the substrate in SiO2@BPs NPs dispersion followed by irradiation. Fluoroalkylsilane was used to obtain hydrophobic top layer. AFM nano manipulation was used to verify the immobilization of NPs. Evaluation of durability was made using air flow at 300 km/hr. Preliminary results indicate the formation of super hydrophobic surfaces (CA>150 and SA<10) with improved stability.

  17. New concept in durability improvement of hip total joint endoprostheses.

    PubMed

    Capitanu, Lucian; Florescu, Virgil; Badita, Liliana-Laura

    2014-01-01

    Starting from the well-known fact that the rolling movement always has a lower friction compared to sliding friction, the authors have conceived and realized a pivoting movement joint on a "layer of balls" with "compensation space", placed between the acetabular cup and the femoral head. This technical solution allows free self-directed migration of the balls, depending on the resistance opposed, with successive occupation of the "compensation space". As a concept, the proposed technical solution excludes the existence of a cage for maintaining the relative positions of the spheres. It can be observed that the smallest values of the force and of the friction coefficient are obtained for the prostheses with balls and self-directed movement (approximately 5 times smaller than the values obtained for a classical prosthesis). For all the couples tested, the friction force grows with the growth of the normal load and of the oscillation speed. Changing the contact mechanism for the artificial hip joint from one sliding contact between two large surfaces, to a multitude of rolling contacts, could lead to some problems regarding functionality and durability of the active prosthesis elements. The key to an accurate evaluation of damaging mechanisms acting on THP with self directed rolling balls is a clear and complete picture of the load transfer mechanism. PMID:24707822

  18. Transparent superwetting nanofilms with enhanced durability at model physiological condition

    PubMed Central

    Hwangbo, Sunghee; Heo, Jiwoong; Lin, Xiangde; Choi, Moonhyun; Hong, Jinkee

    2016-01-01

    There have been many studies on superwetting surfaces owing to the variety of their potential applications. There are some drawbacks to developing these films for biomedical applications, such as the fragility of the microscopic roughness feature that is vital to ensure superwettability. But, there are still only a few studies that have shown an enhanced durability of nanoscale superwetting films at certain extreme environment. In this study, we fabricated intrinsically stable superwetting films using the organosilicate based layer-by-layer (LbL) self-assembly method in order to control nano-sized roughness of the multilayer structures. In order to develop mechanically and chemically robust surfaces, we successfully introduced polymeric silsesquioxane as a building block for LbL assembly with desired fashion. Even in the case that the superhydrophobic outer layers were damaged, the films maintained their superhydrophobicity because of the hydrophobic nature of their inner layers. As a result, we successfully fabricated superwetting nano-films and evaluated their robustness and stability. PMID:26764164

  19. [The problem of durable resistance of plants to different pests].

    PubMed

    Odintsova, I G; Radchenko, E E; Tyryshkin, L G

    2002-01-01

    Different hypotheses concerning durable plant resistance against different pest were tested: 1) resistance is weak and polygenetically controlled; 2) resistance depends on "residual effect" of oligogenes that were overcome by pests. Contrast pair of plants and pests were used in experiments: wheat, barley--facultative parasite Bipolaris sorokiniana Shoem., wheat--obligate parasite Puccinia recondita Rob. ex Desm., sorghum--greenbug Schizaphis graminum Rond. Differential interaction between parasite and host plant resulted in their increased compatibility under long reproduction of parasite on resistant varieties were regarded as criteria of quick overcoming of resistance. The results did not support any hypothesis. The rate of adaptation of B. sorokiniana to the resistant varieties of wheat and barley did not depend on the level of resistance expression (weak, moderate or strong) and genetic control (oligogenic, polygenic or cytoplasmatic). It was shown by hybridological analysis that "residual effect" of oligogenes of sorghum resistance against greenbug depended on small resistance genes, that can be independent or weakly connected with marker oligogene. These data allows to doubt in phenomenon of "residual effect" of oligogenes. It was shown that non specific pathogenicity of parasitic fungi increased during their reproductions on sensitive varieties of plants. Thus, cultivation of sensitive varieties causes damage of crop culture non only because of their own losses, but also by increasing the infection of moderately resistant varieties.

  20. Superhydrophobic durable coating based on UV-photoreactive silica nanoparticles

    SciTech Connect

    Nahum, T.; Dodiuk, H.; Dotan, A.; Kenig, S.; Lellouche, J. P.

    2015-05-22

    Superhydrophobic surfaces with contact angle (CA) >150 and sliding angle (SA) <10 have been aroused curiosity over the years due to their various applications. Superhydrophobicity can be obtained tailoring the chemistry and the roughness of the surface, mimicking the Lotus flower. Most superhydrophobic surfaces based on secondary bonding lose their roughness in harsh conditions and are unsuitable for practical applications. Photoreactive SiO{sub 2} nanoparticles (NPs) based on benzophenone (BP) can be a very effective tool for formation of reactive species that function as a molecular bridge by covalent bonding between the NP and any polymer matrix with C-C and C-H bonds. The present work focused on thermoset radiation curing urethane acrylate. Upon UV irradiation reactive excited nπ* triplet benzophenone species are formed and react through hydrogen abstraction to form ketyl radicals which interact with a radicals from the UV irradiated polymer matrix to yield covalent bonding. Roughness was achieved by dipping the substrate in SiO{sub 2}@BPs NPs dispersion followed by irradiation. Fluoroalkylsilane was used to obtain hydrophobic top layer. AFM nano manipulation was used to verify the immobilization of NPs. Evaluation of durability was made using air flow at 300 km/hr. Preliminary results indicate the formation of super hydrophobic surfaces (CA>150 and SA<10) with improved stability.

  1. Durable strategies to deploy plant resistance in agricultural landscapes.

    PubMed

    Fabre, Frédéric; Rousseau, Elsa; Mailleret, Ludovic; Moury, Benoit

    2012-03-01

    The deployment of resistant crops often leads to the emergence of resistance-breaking pathogens that suppress the yield benefit provided by the resistance. Here, we theoretically explored how farmers' main leverages (resistant cultivar choice, resistance deployment strategy, landscape planning and cultural practices) can be best combined to achieve resistance durability while minimizing yield losses as a result of plant viruses. Assuming a gene-for-gene type of interaction, virus epidemics are modelled in a landscape composed of a mosaic of resistant and susceptible fields, subjected to seasonality, and a reservoir hosting viruses year-round. The model links the genetic and the epidemiological processes, shaping at nested scales the demogenetic dynamics of viruses. The choice of the resistance gene (characterized by the equilibrium frequency of the resistance-breaking virus at mutation-selection balance in a susceptible plant) is the most influential leverage of action. Our results showed that optimal strategies of resistance deployment range from 'mixture' (where susceptible and resistant cultivars coexist) to 'pure' strategies (with only resistant cultivar) depending on the resistance characteristics and the epidemiological context (epidemic incidence and landscape connectivity). We demonstrate and discuss gaps concerning virus epidemiology across the agro-ecological interface that must be filled to achieve sustainable disease management.

  2. 32 CFR 191.6 - Procedures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of this part are fully implemented and are in compliance with the spirit and intent of the DoD Human..., religion, national origin, mental or physical disability, or age. (14) Develop procedures for and...

  3. Prediction of early-age shrinkage cracking in concrete elements

    NASA Astrophysics Data System (ADS)

    Weiss, William Jason

    1999-11-01

    When concrete is prevented from shrinking freely, tensile stresses develop which frequently result in cracking. Cracks in reinforced concrete structures reduce overall durability by allowing the penetration of water and aggressive agents, thereby accelerating the deterioration of the reinforcing steel. Highway pavements, bridge decks, and industrial floors are especially susceptible to this type of deterioration since these structures exhibit high rates of shrinkage and are frequently exposed to aggressive environmental conditions. The objectives of this investigation included the development of experimental procedures for assessing shrinkage cracking potential, the evaluation of mix composition on shrinkage cracking potential, and the development of theoretical models to simulate early-age cracking behavior. Specifically, the influence of a shrinkage-reducing admixture (SRA) was investigated. The shrinkage-reducing admixture substantially reduces free shrinkage and restrained shrinkage cracking while providing similar mechanical properties. An experimental procedure was developed in which a pressurized cylindrical specimen was used to assess tensile creep. Electrical properties were investigated using impedance spectroscopy to evaluate the moisture profiles of drying and wetting concrete. Restrained shrinkage experiments were developed and shrinkage cracking was shown to be size/geometry dependent, even though shrinkage strains and residual stress levels were comparable. A fracture mechanics modeling approach was developed to predict the behavior of a variety of restrained concrete specimens. This modeling approach was used to successfully explain experimental results from a variety of mixture compositions and specimen geometries. The model was used to demonstrate the influence of material and structural properties on the potential for cracking. A favorable correlation was observed between the predictions of the fracture-based model and the experimentally observed

  4. Petrophysical behaviour and durability of the Miocene sandstones used in the architectural heritage of Tunisia (Roman aqueduct of Oued Miliane and Uthina Roman site)

    NASA Astrophysics Data System (ADS)

    Zoghlami, K.; Gómez-Gras, D.

    2009-09-01

    SummaryIn the present work, the relationship between intrinsic factors, mechanical properties and durability of Miocene sandstones used in the architectural heritage of Tunisia, specifically in the Roman aqueduct of Oued Miliane and Uthina site, are studied. The petrographic study and the characterisation of porous network have been carried out using optical microscopy, mercury intrusion porosimetry and laser scanner confocal microscopy (LSCM). The hygric behaviour has also been determined from water absorption under vacuum, drying, capillary water absorption and water vapour permeability. The mechanical properties have been assessed from compressive strength and abrasion tests. Rock durability has been evaluated from salt crystallization (sodium sulphate) accelerated aging tests. The results show good hygric behaviour characterised by a high evaporation rate and almost no retention of water; due to the macroporous character of the rock and the good connectivity of the pore network. Because of the poor lithification, the stone has a very low mechanical strength which makes it very vulnerable to the salt crystallization effects. The absence of chemically unstable minerals preserves the rock from chemical alteration. The durability of the building stone is mainly conditioned by salt loading of the monument.

  5. Durability of solvent-free one-step self-etch adhesive under simulated intrapulpal pressure

    PubMed Central

    2015-01-01

    Background There are different solvents presented in simplified adhesives. Bond-1 SF has been developed, which contains neither water nor organic solvents, in order to eliminate technical issues in terms of evaporation of solvents and concerns for the durability of resin-dentin bond. Thus this study was conducted to evaluate the microtensile bond strength (?TBS) of solvent-free and ethanol-based one-step self-etch adhesives to dentin under simulated intrapulpal pressure (IPP). Material and Methods Occlusal surfaces of human molars were prepared to expose mid-dentin depth. Bond-1SF Solvent-Free SE [SF] and AdperTM easy one adhesives [AE] were applied on dentin specimens. Resin composite build up was done in increments. Then specimens were stored under simulated IPP 20 mmHg, immersed in artificial saliva at 37 ºC for 24 hours (24h) and 6 months (6m). Specimens were sectioned into sticks of (1 mm²) to be tested for (?TBS) using a universal testing machine. Both fractured sections of each stick were inspected using a stereomicroscope at 40× magnification to determine the mode of failure. Data were statistically analyzed by Two-way ANOVA of Variance. Results There was no statistically significant difference between the mean ?TBS of both [SF] and [AE] adhesives at both aging periods, 24h and 6m (p< 0.1103) and (p< 0.7148) respectively. Only for [AE] there was statistical significance for aging periods (p< 0.0057*). The most represented modes of failure were adhesive failure at tooth side. Conclusions Under simulated IPP solvent-free adhesive [SF] had comparable performance as ethanol-based adhesive [AE] when bonded to dentin substrate. Key words:Bond strength, dentin, simulated intrapulpal pressure, self-etch adhesives, solvents. PMID:26535091

  6. Long-term mechanical durability of dental nanocomposites containing amorphous calcium phosphate nanoparticles

    PubMed Central

    Moreau, Jennifer L.; Weir, Michael D.; Giuseppetti, Anthony A.; Chow, Laurence C.; Antonucci, Joseph M.; Xu, Hockin H. K.

    2012-01-01

    Half of all dental restorations fail within 10 years, with secondary caries and restoration fracture being the main reasons. Calcium phosphate (CaP) composites can release Ca and PO4 ions and remineralize tooth lesions. However, there has been no report on their long-term mechanical durability. The objective of this study was to investigate the wear, thermal-cycling, and water-aging of composites containing amorphous calcium phosphate nanoparticles (NACP). NACP of 112-nm and glass particles were used to fabricate four composites: (1) 0% NACP+75% glass; (2) 10% NACP+65% glass; (3) 15% NACP+60% glass; and (4) 20% NACP+50% glass. Flexural strength and elastic modulus of NACP nanocomposites were not degraded by thermal-cycling. Wear depth increased with increasing NACP filler level. Wear depths of NACP nanocomposites after 4 × 105 cycles were within the range for commercial controls. Mechanical properties of all the tested materials decreased with water-aging time. After 2 years, the strengths of NACP nanocomposites were moderately higher than the control composite, and much higher than the resin-modified glass ionomers. The mechanism of strength loss for resin-modified glass ionomer was identified as microcracking and air-bubbles. NACP nanocomposites and control composite were generally free of microcracks and air-bubbles. In conclusion, combining NACP nanoparticles with reinforcement glass particles resulted in novel nanocomposites with long-term mechanical properties higher than those of commercial controls, and wear within the range of commercial controls. These strong long-term properties, plus the Ca-PO4 ion release and acid-neutralization capability reported earlier, suggest that the new NACP nanocomposites may be promising for stress-bearing and caries-inhibiting restorations. PMID:22514160

  7. Long-term mechanical durability of dental nanocomposites containing amorphous calcium phosphate nanoparticles.

    PubMed

    Moreau, Jennifer L; Weir, Michael D; Giuseppetti, Anthony A; Chow, Laurence C; Antonucci, Joseph M; Xu, Hockin H K

    2012-07-01

    Half of all dental restorations fail within 10 years, with secondary caries and restoration fracture being the main reasons. Calcium phosphate (CaP) composites can release Ca and PO(4) ions and remineralize tooth lesions. However, there has been no report on their long-term mechanical durability. The objective of this study was to investigate the wear, thermal-cycling, and water-aging of composites containing amorphous calcium phosphate nanoparticles (NACP). NACP of 112-nm and glass particles were used to fabricate four composites: (1) 0% NACP+75% glass; (2) 10% NACP+65% glass; (3) 15% NACP+60% glass; and (4) 20% NACP+50% glass. Flexural strength and elastic modulus of NACP nanocomposites were not degraded by thermal-cycling. Wear depth increased with increasing NACP filler level. Wear depths of NACP nanocomposites after 4 × 10(5) cycles were within the range for commercial controls. Mechanical properties of all the tested materials decreased with water-aging time. After 2 years, the strengths of NACP nanocomposites were moderately higher than the control composite, and much higher than the resin-modified glass ionomers. The mechanism of strength loss for resin-modified glass ionomer was identified as microcracking and air-bubbles. NACP nanocomposites and control composite were generally free of microcracks and air-bubbles. In conclusion, combining NACP nanoparticles with reinforcement glass particles resulted in novel nanocomposites with long-term mechanical properties higher than those of commercial controls, and wear within the range of commercial controls. These strong long-term properties, plus the Ca-PO(4) ion release and acid-neutralization capability reported earlier, suggest that the new NACP nanocomposites may be promising for stress-bearing and caries-inhibiting restorations.

  8. A thermally stable, durable and temperature-dependent oleophobic surface of a polymethylsilsesquioxane film.

    PubMed

    Urata, Chihiro; Masheder, Benjamin; Cheng, Dalton F; Hozumi, Atsushi

    2013-04-25

    Polymethylsilsesquioxane (PMSQ) films prepared by a simple sol-gel reaction of methyltriethoxysilane were found to possess thermally stable, durable, and temperature-dependent oleophobic properties under high temperature (~350 °C) conditions. PMID:23493793

  9. State-of-the-Art Fuel Cell Voltage Durability Status: Spring 2013 Composite Data Products

    SciTech Connect

    Kurtz, J.; Sprik, S.; Saur, G.; Peters, M.; Post, M.; Ainscough, C.

    2013-05-01

    This presentation from the U.S. Department of Energy's National Renewable Energy Laboratory includes composite data products (CDPs) produced in 2013 for state-of-the-art fuel cell voltage durability status.

  10. Chemical durability of lead-oxide-based, thick-film binder glasses

    SciTech Connect

    Mattox, D.M.; Robinson, J.H.

    1997-05-01

    Lead-oxide-bearing glasses are incompatible with aluminum nitride metallizations, and federal legislation is recommending their replacement in thick-film electronics and labeling. To evaluate alternatives, the benchmark chemical durabilities of the lead borosilicate and lead aluminate thick-film binder glasses have been determined. Aluminum oxide (Al{sub 2}O{sub 3}) benefits water durability moderately, acid durability substantially, and basic durability indistinguishably. The rate of attack in water is approximately two orders of magnitude greater than for soda-lime glass. The thermal contractions of the glasses are compatible. An apparent, spontaneous phase separation in the Al{sub 2}O{sub 3}-free glass is suppressed by Al{sub 2}O{sub 3} that is included as a batch component.

  11. Recent Advances in Durability and Damage Tolerance Methodology at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Ransom, J. B.; Glaessgen, E. H.; Raju, I. S.; Harris, C. E.

    2007-01-01

    Durability and damage tolerance (D&DT) issues are critical to the development of lighter, safer and more efficient aerospace vehicles. Durability is largely an economic life-cycle design consideration whereas damage tolerance directly addresses the structural airworthiness (safety) of the vehicle. Both D&DT methodologies must address the deleterious effects of changes in material properties and the initiation and growth of damage that may occur during the vehicle s service lifetime. The result of unanticipated D&DT response is often manifested in the form of catastrophic and potentially fatal accidents. As such, durability and damage tolerance requirements must be rigorously addressed for commercial transport aircraft and NASA spacecraft systems. This paper presents an overview of the recent and planned future research in durability and damage tolerance analytical and experimental methods for both metallic and composite aerospace structures at NASA Langley Research Center (LaRC).

  12. Monitoring the Durability Performance of Concrete in Nuclear Waste Containment. Technical Progress Report No. 3

    SciTech Connect

    Ulm, Franz-Josef

    2000-03-31

    OAK-B135 Monitoring the Durability Performance of Concrete in Nuclear Waste Containment. Technical Progress Report No. 3(NOTE: Part II A item 1 indicates ''PAPER'', but a report is attached electronically)

  13. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

    PubMed Central

    Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-01-01

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining. PMID:26482559

  14. Materials research for high-speed civil transport and generic hypersonics: Composites durability

    NASA Technical Reports Server (NTRS)

    Allen-Lilly, Heather; Cregger, Eric; Hoffman, Daniel; Mccool, Jim

    1995-01-01

    This report covers a portion of an ongoing investigation of the durability of composites for the High Speed Civil Transport (HSCT) program. Candidate HSCT composites need to possess the high-temperature capability required for supersonic flight. This program was designed to initiate the design, analysis, fabrication, and testing of equipment intended for use in validating the long-term durability of materials for the HSCT. This equipment includes thermally actuated compression and tension fixtures, hydraulic-actuated reversible load fixtures, and thermal chambers. This equipment can be used for the durability evaluation of both composite and adhesive materials. Thermally actuated fixtures are recommended for fatigue cycling when long-term thermomechanical fatigue (TMF) data are required on coupon-sized tension or compression specimens. Long term durability testing plans for polymer matrix composite specimens are included.

  15. Durability and Reliability of Large Diameter HDPE Pipe for Water Main Applications (Web Report 4485)

    EPA Science Inventory

    Research validates HDPE as a suitable material for use in municipal piping systems, and more research may help users maximize their understanding of its durability and reliability. Overall, corrosion resistance, hydraulic efficiency, flexibility, abrasion resistance, toughness, f...

  16. Dual-layered-coated mechanically-durable superomniphobic surfaces with anti-smudge properties.

    PubMed

    Muthiah, Palanikkumaran; Bhushan, Bharat; Yun, Kyungsung; Kondo, Hirofumi

    2013-11-01

    Bio-inspired surfaces that exhibit high contact angle and low contact angle hysteresis for various liquids and demonstrate mechanical durability and anti-smudge properties are of interest for various applications. The fabrication of such surfaces has often involved complex or expensive processes, required techniques that may not be suitable for various substrates and particles, may require surface post-treatment, or may lack durability. Dual layered coatings of roughness-induced superomniphobic surfaces that demonstrate good mechanical durability were fabricated on glass substrates using hydrophobic SiO2 nanoparticles and low surface energy fluorobinders using dip coating and spray coating techniques. The particle-to-binder ratio was optimized for contact angles of interest. The mechanical durability of these coatings was examined under mechanical rubbing action. The anti-smudge properties were examined by wiping an artificially contaminated coating using oil-impregnated microfiber cloth.

  17. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel.

    PubMed

    Tesler, Alexander B; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-10-20

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

  18. A thermally stable, durable and temperature-dependent oleophobic surface of a polymethylsilsesquioxane film.

    PubMed

    Urata, Chihiro; Masheder, Benjamin; Cheng, Dalton F; Hozumi, Atsushi

    2013-04-25

    Polymethylsilsesquioxane (PMSQ) films prepared by a simple sol-gel reaction of methyltriethoxysilane were found to possess thermally stable, durable, and temperature-dependent oleophobic properties under high temperature (~350 °C) conditions.

  19. Test Plans. Lightweight Durable TPS: Tasks 1,2,4,5, and 6

    NASA Technical Reports Server (NTRS)

    Greenberg, H. S.; Tu, Tina

    1994-01-01

    The objective of this task is to develop the fluted core flexible blankets, also referred to as the Tailorable Advanced Blanket Insulation (TABI), to a technology readiness level (TRL) of 6. This task is one of the six tasks under TA 3, Lightweight Durable TPS study, of the Single Stage to Orbit (SSTO) program. The purpose of this task is to develop a durable and low maintenance flexible TPS blanket material to be implemented on the SSTO vehicle.

  20. Durability aspects of polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Sethuraman, Vijay Anand

    In order for the successful adoption of proton exchange membrane (PEM) fuel cell technology, it is imperative that durability is understood, quantified and improved. A number of mechanisms are known to contribute to PEMFC membrane electrode assembly (MEA) performance degradation. In this dissertation, we show, via experiments, some of the various processes that degrade the proton exchange membrane in a PEM fuel cell; and catalyst poisoning due to hydrogen sulfide (H2S) and siloxane. The effect of humidity on the chemical stability of two types of membranes, [i.e., perfluorosulfonic acid type (PFSA, NafionRTM 112) and biphenyl sulfone hydrocarbon type, (BPSH-35)] was studied by subjecting the MEAs to open-circuit voltage (OCV) decay and potential cycling tests at elevated temperatures and low inlet gas relative humidities. The BPSH-35 membranes showed poor chemical stability in ex situ Fenton tests compared to that of NafionRTM membranes. However, under fuel cell conditions, BPSH-35 MEAs outperformed NafionRTM 112 MEAs in both the OCV decay and potential cycling tests. For both membranes, (i) at a given temperature, membrane degradation was more pronounced at lower humidities and (ii) at a given relative humidity operation, increasing the cell temperature accelerated membrane degradation. Mechanical stability of these two types of membranes was also studied using relative humidity (RH) cycling. Hydrogen peroxide (H2O2) formation rates in a proton exchange membrane (PEM) fuel cell were estimated by studying the oxygen reduction reaction (ORR) on a rotating ring disc electrode (RRDE). Fuel cell conditions were replicated by depositing a film of Pt/Vulcan XC-72 catalyst onto the disk and by varying the temperature, dissolved O2 concentration and the acidity levels in HClO4. The HClO4 acidity was correlated to ionomer water activity and hence fuel cell humidity. H 2O2 formation rates showed a linear dependence on oxygen concentration and square dependence on water

  1. FLUIDIZED BED STEAM REFORMED MINERAL WASTE FORMS: CHARACTERIZATION AND DURABILITY TESTING

    SciTech Connect

    Jantzen, C; Troy Lorier, T; John Pareizs, J; James Marra, J

    2006-12-06

    Fluidized Bed Steam Reforming (FBSR) is being considered as a potential technology for the immobilization of a wide variety of high sodium low activity wastes (LAW) such as those existing at the Hanford site, at the Idaho National Laboratory (INL), and the Savannah River Site (SRS). The addition of clay, charcoal, and a catalyst as co-reactants with the waste denitrates the aqueous wastes and forms a granular mineral waste form that can subsequently be made into a monolith for disposal if necessary. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage and ring structures and iron bearing spinel minerals. The mineralization occurs at moderate temperatures between 650-750 C in the presence of superheated steam. The cage and ring structured feldspathoid minerals atomically bond radionuclides like Tc-99 and Cs-137 and anions such as SO{sub 4}, I, F, and Cl. The spinel minerals stabilize Resource Conservation and Recovery Act (RCRA) hazardous species such as Cr and Ni. Granular mineral waste forms were made from (1) a basic Hanford Envelope A low activity waste (LAW) simulant and (2) an acidic INL simulant commonly referred to as sodium bearing waste (SBW) in pilot scale facilities at the Science Applications International Corporation (SAIC) Science and Technology Applications Research (STAR) facility in Idaho Falls, ID. The FBSR waste forms were characterized and the durability tested via ASTM C1285 (Product Consistency Test), the Environmental Protection Agency (EPA) Toxic Characteristic Leaching Procedure (TCLP), and the Single Pass Flow Through (SPFT) test. The results of the SPFT testing and the activation energies for dissolution are discussed in this study.

  2. FLUIDIZED BED STEAM REFORMED MINERAL WASTE FORMS: CHARACTERIZATION AND DURABILITY TESTING

    SciTech Connect

    Jantzen, C; Troy Lorier, T; John Pareizs, J; James Marra, J

    2007-03-31

    Fluidized Bed Steam Reforming (FBSR) is being considered as a potential technology for the immobilization of a wide variety of high sodium low activity wastes (LAW) such as those existing at the Hanford site, at the Idaho National Laboratory (INL), and the Savannah River Site (SRS). The addition of clay, charcoal, and a catalyst as co-reactants with the waste denitrates the aqueous wastes and forms a granular mineral waste form that can subsequently be made into a monolith for disposal if necessary. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage and ring structures and iron bearing spinel minerals. The mineralization occurs at moderate temperatures between 650-750 C in the presence of superheated steam. The cage and ring structured feldspathoid minerals atomically bond radionuclides like Tc-99 and Cs-137 and anions such as SO4, I, F, and Cl. The spinel minerals stabilize Resource Conservation and Recovery Act (RCRA) hazardous species such as Cr and Ni. Granular mineral waste forms were made from (1) a basic Hanford Envelope A low-activity waste (LAW) simulant and (2) an acidic INL simulant commonly referred to as sodium bearing waste (SBW) in pilot scale facilities at the Science Applications International Corporation (SAIC) Science and Technology Applications Research (STAR) facility in Idaho Falls, ID. The FBSR waste forms were characterized and the durability tested via ASTM C1285 (Product Consistency Test), the Environmental Protection Agency (EPA) Toxic Characteristic Leaching Procedure (TCLP), and the Single Pass Flow Through (SPFT) test. The results of the SPFT testing and the activation energies for dissolution are discussed in this study.

  3. Enhanced durability of desulfurization sorbents for fluidized-bed applications

    SciTech Connect

    Gupta, R.P.; Gangwal, S.K.

    1992-11-01

    To extend the operating temperature range and further improve the durability of fluidizable sorbents, zinc titanate, another leading regenerable sorbent, was selected for development in the later part of this project. A number of zinc titanate formulations were prepared in the 50 to 300 [mu]m range using granulation and spray drying methods. Important sorbent preparation variables investigated included zinc to titanium ratio, binder type, binder amount, and various chemical additives such as cobalt and molybdenum. A number of sorbents selected on the basis of screening tests were subjected to bench-scale testing for 10 cycles at high temperature, high pressure (HTHP) conditions using the reactor system designed and constructed during the base program. This reactor system is capable of operation either as a 2.0 in. or 3.0 in. I.D. bubbling bed and is rated up to 20 atm operation at 871[degrees]C. Bench-scale testing variables included sorbent type, temperature (550 to 750[degrees]C), gas type (KRW or Texaco gasifier gas), steam content of coal gas, and fluidizing gas velocity (6 to 15 cm/s). The sorbents prepared by spray drying showed poor performance in terms of attrition resistance and chemical reactivity. On the other hand, the granulation method proved to be very successful. For example, a highly attrition-resistant zinc titanate formulation, ZT-4, prepared by granulation exhibited virtually no zinc loss and demonstrated a constant high reactivity and sulfur capacity over 10 cycles, i.e., approximately a 60 percent capacity utilization, with Texaco gas at 750[degrees]C, 15 cm/s fluidizing velocity and 15 atm pressure. The commercial potential of the granulation method for zinc titanate manufacture was demonstrated by preparing two 80 lb batches of sorbent with zinc to titanium mol ratios of 0.8 and 1.5.

  4. Enhanced durability of desulfurization sorbents for fluidized-bed applications

    SciTech Connect

    Gupta, R.P.; Gangwal, S.K.

    1992-11-01

    To extend the operating temperature range and further improve the durability of fluidizable sorbents, zinc titanate, another leading regenerable sorbent, was selected for development in the later part of this project. A number of zinc titanate formulations were prepared in the 50 to 300 {mu}m range using granulation and spray drying methods. Important sorbent preparation variables investigated included zinc to titanium ratio, binder type, binder amount, and various chemical additives such as cobalt and molybdenum. A number of sorbents selected on the basis of screening tests were subjected to bench-scale testing for 10 cycles at high temperature, high pressure (HTHP) conditions using the reactor system designed and constructed during the base program. This reactor system is capable of operation either as a 2.0 in. or 3.0 in. I.D. bubbling bed and is rated up to 20 atm operation at 871{degrees}C. Bench-scale testing variables included sorbent type, temperature (550 to 750{degrees}C), gas type (KRW or Texaco gasifier gas), steam content of coal gas, and fluidizing gas velocity (6 to 15 cm/s). The sorbents prepared by spray drying showed poor performance in terms of attrition resistance and chemical reactivity. On the other hand, the granulation method proved to be very successful. For example, a highly attrition-resistant zinc titanate formulation, ZT-4, prepared by granulation exhibited virtually no zinc loss and demonstrated a constant high reactivity and sulfur capacity over 10 cycles, i.e., approximately a 60 percent capacity utilization, with Texaco gas at 750{degrees}C, 15 cm/s fluidizing velocity and 15 atm pressure. The commercial potential of the granulation method for zinc titanate manufacture was demonstrated by preparing two 80 lb batches of sorbent with zinc to titanium mol ratios of 0.8 and 1.5.

  5. The durability of examination gloves used on intensive care units

    PubMed Central

    2013-01-01

    Background The use of examination gloves is part of the standard precautions to prevent medical staff from transmission of infectious agents between patients. Gloves also protect the staff from infectious agents originating from patients. Adequate protection, however, depends on intact gloves. The risk of perforation of examination gloves is thought to correlate with duration of wearing, yet, only very few prospective studies have been performed on this issue. Methods A total number of 1500 consecutively used pairs of examination gloves of two different brands and materials (latex and nitrile) were collected over a period of two months on two ICU’s. Used gloves were examined for micro perforations using the “water-proof-test” according to EN 455–1. Cox-regression for both glove types was used to estimate optimal changing intervals. Results Only 26% of gloves were worn longer than 15 min. The total perforation rate was 10.3% with significant differences and deterioration of integrity of gloves between brands (p<0.001). Apart from the brand, “change of wound dressing” (p = 0.049) and “washing patients” (p = 0.001) were also significantly associated with an increased risk of perforation. Conclusion Medical gloves show marked differences in their durability that cannot be predicted based on the technical data routinely provided by the manufacturer. Based on the increase of micro perforations over time and the wearing behavior, recommendations for maximum wearing time of gloves should be given. Changing of gloves after 15 min could be a good compromise between feasibility and safety. HCWs should be aware of the benefits and limitations of medical gloves. To improve personal hygiene hand disinfection should be further encouraged. PMID:23687937

  6. Advanced Stirling Convertor Heater Head Durability and Reliability Quantification

    NASA Technical Reports Server (NTRS)

    Krause, David L.; Shah, Ashwin R.; Korovaichuk, Igor; Kalluri, Sreeramesh

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has identified the high efficiency Advanced Stirling Radioisotope Generator (ASRG) as a candidate power source for long duration Science missions, such as lunar applications, Mars rovers, and deep space missions, that require reliable design lifetimes of up to 17 years. Resistance to creep deformation of the MarM-247 heater head (HH), a structurally critical component of the ASRG Advanced Stirling Convertor (ASC), under high temperatures (up to 850 C) is a key design driver for durability. Inherent uncertainties in the creep behavior of the thin-walled HH and the variations in the wall thickness, control temperature, and working gas pressure need to be accounted for in the life and reliability prediction. Due to the availability of very limited test data, assuring life and reliability of the HH is a challenging task. The NASA Glenn Research Center (GRC) has adopted an integrated approach combining available uniaxial MarM-247 material behavior testing, HH benchmark testing and advanced analysis in order to demonstrate the integrity, life and reliability of the HH under expected mission conditions. The proposed paper describes analytical aspects of the deterministic and probabilistic approaches and results. The deterministic approach involves development of the creep constitutive model for the MarM-247 (akin to the Oak Ridge National Laboratory master curve model used previously for Inconel 718 (Special Metals Corporation)) and nonlinear finite element analysis to predict the mean life. The probabilistic approach includes evaluation of the effect of design variable uncertainties in material creep behavior, geometry and operating conditions on life and reliability for the expected life. The sensitivity of the uncertainties in the design variables on the HH reliability is also quantified, and guidelines to improve reliability are discussed.

  7. Randomized clinical trial comparing abluminal biodegradable polymer sirolimus-eluting stents with durable polymer sirolimus-eluting stents

    PubMed Central

    Zhang, Haijun; Wang, Xiangfei; Deng, Wei; Wang, Shenguo; Ge, Junbo; Toft, Egon

    2016-01-01

    Abstract Background: The biodegradable polymer drug-eluting stents (DES) were developed to improve vascular healing. However, further data and longer-term follow-up are needed to confirm safety and efficacy of these stents. This randomized clinical trial aimed to compare safety and efficacy of 2 sirolimus-eluting stents (SES): Cordimax—a novel abluminal biodegradable polymer SES and Cypher Select—a durable polymer SES, at 9 months angiographic and 5-year clinical follow-up. Methods: We randomized 402 patients with coronary artery disease to percutaneous coronary intervention with Cordimax (n = 202) or Cypher select (n = 200). Angiographic follow-up was performed at 9 months after the index procedure and clinical follow-up annually up to 5 years. The primary endpoint was angiographic in-stent late luminal loss (LLL). Secondary endpoints included angiographic restenosis rate, target vessel revascularization (TVR), and major adverse cardiac events (MACEs; defined as cardiac death, myocardial infarction, or TVR) at 5-year follow-up. Results: Cordimax was noninferior to Cypher select for in-stent LLL (0.25 ± 0.47 vs 0.18 ± 0.49 mm; P = 0.587) and in-stent mean diameter stenosis (22.19 ± 12.21% vs 19.89 ± 10.79%; P = 0.064) at 9 months angiographic follow-up. The MACE rates were not different at 1 year (5.9% vs 4.0%, P = 0.376); however, MACE rates from 2 to 5 years were lower in the Cordimax group (6.8% vs 13.1%; P = 0.039). Conclusion: Abluminal biodegradable polymer SES is noninferior to durable polymer SES at 9-month angiographic and 1-year clinical follow-up. However, MACE rates from 2 to 5 years were less in the abluminal biodegradable polymer group. PMID:27661023

  8. Percutaneous Procedures for the Treatment of Trigeminal Neuralgia.

    PubMed

    Bender, Matthew T; Bettegowda, Chetan

    2016-07-01

    Three major percutaneous procedures are currently used to treat trigeminal neuralgia (TN). Percutaneous balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation interrupt afferent pain fibers by injury to the trigeminal nerve root or ganglion. Each is capable of offering immediate and durable pain relief. Each is associated with relatively low, but variable rates of complications. Patient heterogeneity, technical variation, and nonstandard outcomes plague the existing outcomes literature and limit comparisons of treatments. Rendering treatment selection a function of individual physician preference and practice patterns. Randomized, prospective trials are needed; in the meantime, percutaneous rhizotomy remains an excellent treatment for selected patients.

  9. Percutaneous Procedures for the Treatment of Trigeminal Neuralgia.

    PubMed

    Bender, Matthew T; Bettegowda, Chetan

    2016-07-01

    Three major percutaneous procedures are currently used to treat trigeminal neuralgia (TN). Percutaneous balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation interrupt afferent pain fibers by injury to the trigeminal nerve root or ganglion. Each is capable of offering immediate and durable pain relief. Each is associated with relatively low, but variable rates of complications. Patient heterogeneity, technical variation, and nonstandard outcomes plague the existing outcomes literature and limit comparisons of treatments. Rendering treatment selection a function of individual physician preference and practice patterns. Randomized, prospective trials are needed; in the meantime, percutaneous rhizotomy remains an excellent treatment for selected patients. PMID:27324995

  10. Accelerated aging of polymer composite bridge materials

    NASA Astrophysics Data System (ADS)

    Carlson, Nancy M.; Blackwood, Larry G.; Torres, Lucinda L.; Rodriguez, Julio G.; Yoder, Timothy S.

    1999-05-01

    Accelerated aging research on samples of composite materials and candidate UV protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory. Durability results and sensor data form test with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards and acceptance criteria for PMC bridges for use in the transportation infrastructure.

  11. Accelerated Aging of Polymer Composite Bridge Materials

    SciTech Connect

    Carlson, Nancy Margaret; Blackwood, Larry Gene; Torres, Lucinda Laine; Rodriguez, Julio Gallardo; Yoder, Timothy Scott

    1999-03-01

    Accelerated aging research on samples of composite material and candidate ultraviolet (UV) protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory (INEEL). Durability results and sensor data from tests with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards, and acceptance criteria for PMC bridges for use in the transportation infrastructure.

  12. NREL Determines Better Testing Methods for Photovoltaic Module Durability (Fact Sheet), NREL Highlights, Research & Development

    SciTech Connect

    Not Available

    2011-11-01

    NREL discoveries will enable manufacturers to produce more robust photovoltaic modules. Over the past decade, some photovoltaic (PV) modules have experienced power losses because of the system voltage stress that modules experience in fielded arrays. This is partly because qualification tests and standards do not adequately evaluate the durability of modules that undergo the long-term effects of high voltage. Scientists at the National Renewable Energy Laboratory (NREL) tried various testing methods and stress levels to demonstrate module durability to system voltage potential-induced degradation (PID) mechanisms. The results of these accelerated tests, along with outdoor testing, were used to estimate the acceleration factors needed to more accurately evaluate the durability of modules to system voltage stress. NREL was able to determine stress factors, levels, and methods for testing based on the stresses experienced by modules in the field. These results, in combination with those in the literature, suggest that constant stress with humidity and system voltage is more damaging than stress applied intermittently or with periods of recovery comprising hot and dry conditions or alternating bias in between. NREL has determined some module constructions to be extremely durable to PID. These findings will help the manufacturers of PV materials and components produce more durable products that better satisfy their customers. NREL determined that there is rapid degradation of some PV modules under system voltage stress and evaluated degradation rates in the field to develop more accurate accelerated testing methods. PV module manufacturers will be better able to choose robust materials and durable designs and guarantee sturdier, longer-lasting products. As PV modules become more durable, and thus more efficient over the long term, the risks and the cost of PV power will be reduced.

  13. Durable Nanolayer Graft Polymerization of Functional Finishes Using Atmospheric Plasma

    NASA Astrophysics Data System (ADS)

    Mazloumpour, Maryam

    . Furthermore, spunbond nonwoven polypropylene fabric, commonly used for hygienic products, was treated with diallyldimethylammonium chloride (DADMAC). Atmospheric pressure glow discharge plasma was used to induce free radical chain polymerization of the ADMAC monomer, which conferred a graft polymerized network on the fabric with durable antimicrobial properties. The effect of different DADMAC concentration, and plasma conditions including the RF power and the time of plasma exposure were studied and the optimum treatment conditions were identified by calculating the surface charge density on the treated fabrics. The presence of poly-DADMAC on the polypropylene surface was confirmed using SEM, FT-IR and TOF-SIMS. Antibacterial performance was investigated using standard test methods (AATCC TM 100) for both gram positive and gram negative bacteria. The antimicrobial results showed 6 log reductions in the bacterial activities of K. pneumoniae and S .aureus, which was unprecedented using a plasma-induced graft polymerization approach.

  14. 40 CFR Appendix Xv to Part 86 - Procedure for Determining an Acceptable Exhaust Regeneration Durability-Data Test Schedule for...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 5,000, 25,000, 50,000, 75,000, and 100,000 miles will be designated as the standard (std) test... = [∑(Xs)2 − ((∑Xs)2 / Ns))std Where: Xs = Individual mileages at which the vehicle will be tested. Ns... to table I and determine tp at (Np − 2)prop degrees of freedom and ts at (Ns − 2)std degrees...

  15. High temperature and environmental effects on the durability of Ti-6Al-4V/FM5 adhesive bonded system

    SciTech Connect

    Parvatareddy, H.; Pasricha, A.; Dillard, D.A.; Holmes, B.; Dillard, J.G.

    1997-12-31

    A fracture mechanics based approach using wedge and double cantilever beam (DCB) specimens is used to evaluate the durability of a titanium/adhesive system. The adhesive used was a polyimide developed by NASA Langley Research Center, modified and supplied by Cytec Engineered Materials, Inc., and designated as FM5. Prior to bonding, the adherend surfaces were pretreated by one of two surface pretreatments: phenylethynyl trimethyl silane or chromic acid anodization. Samples were aged at one of three different temperatures, 150, 177, and 204 C, all of which are well below the glass transition temperature of the adhesive. Aging was also carried out in one of three different environments, ambient atmospheric air and reduced air pressures of 2 psi air (13.8 KPa) and 0.2 psi air (1.38 KPa), for several months. Samples aged for different times were then tested to evaluate both static and fatigue properties. Results obtained thus far indicate that the greatest loss in strength occurs after aging in air at the highest aging temperature of 204 C. Strain energy release rate G values obtained from the static DCB tests dropped by 10 to 20% after aging for periods of up to 6 months. Solvent uptake tests were conducted on neat FM5 resin in several common organic solvents followed by tensile tests to evaluate both saturated and residual properties. Strain energy release rate values were also computed from wedge tests of samples immersed in the different solvents for several days. Results showed the FM5 resin to be quite solvent resistant.

  16. Durability of crosslinked polydimethylsyloxanes: the case of composite insulators

    NASA Astrophysics Data System (ADS)

    Delor-Jestin, Florence; Tomer, Namrata S.; Pal Singh, Raj; Lacoste, Jacques

    2008-04-01

    Most applications of silicones are linked to their hydrophobic properties and (or) their high resistance to ageing (e.g. thermal ageing and photoageing). However, when placed in extreme environments, these materials can fail as in the case of epoxy/fiber glass composite powerlines insulators, where crosslinked polymethylsyloxanes (PDMSs) are used as the protective envelope (housing) of the insulator. We report on the behavior of both pure/noncrosslinked PDMSs and typical formulations used in industrial insulators, i.e. containing peroxide crosslinked PDMS, alumina trioxide hydrated (ATH) and silica. Special attention is paid on both (i) the sources of potential degradation and (ii) the best analytical methods that can be applied to the study of very complex formulations. (i) Aside from conventional types of ageing such as photo-ageing and thermal, hydrolytic, and service life ageings, treatments with acidic vapors, plasma and ozone possibly generating species from the reaction of a high electric field with air were also performed, which allowed to accelerate electrical and out-door ageings and to obtain differently aged materials. (ii) Aside from conventional analytical methods of polymer degradation such as FTIR/ATR spectroscopy and SEC, TG, hardness measurements, more specific methods like photo/DSC, TG/IR, thermoporosimetry, resistivity and density measurements were also performed to characterize the chemical and physical evolutions of polymer materials. In particular, it was found that treatment with nitric acid vapor has detrimental effects on the properties of both fire retardants (e.g. ATH) and PDMSs, affecting the hardness and resistivity of the formulated material.

  17. Designing Flightdeck Procedures

    NASA Technical Reports Server (NTRS)

    Barshi, Immanuel; Mauro, Robert; Degani, Asaf; Loukopoulou, Loukia

    2016-01-01

    The primary goal of this document is to provide guidance on how to design, implement, and evaluate flight deck procedures. It provides a process for developing procedures that meet clear and specific requirements. This document provides a brief overview of: 1) the requirements for procedures, 2) a process for the design of procedures, and 3) a process for the design of checklists. The brief overview is followed by amplified procedures that follow the above steps and provide details for the proper design, implementation and evaluation of good flight deck procedures and checklists.

  18. Computerized procedures system

    DOEpatents

    Lipner, Melvin H.; Mundy, Roger A.; Franusich, Michael D.

    2010-10-12

    An online data driven computerized procedures system that guides an operator through a complex process facility's operating procedures. The system monitors plant data, processes the data and then, based upon this processing, presents the status of the current procedure step and/or substep to the operator. The system supports multiple users and a single procedure definition supports several interface formats that can be tailored to the individual user. Layered security controls access privileges and revisions are version controlled. The procedures run on a server that is platform independent of the user workstations that the server interfaces with and the user interface supports diverse procedural views.

  19. Prediction of radioactive waste glass durability by the hydration thermodynamic model: Application to saturated repository environments

    SciTech Connect

    Jantzen, C.M. ); Ramsey, W.G. . Dept. of Ceramic Engineering)

    1989-01-01

    The effects of groundwater chemistry on glass durability were examined using the hydration thermodynamic model. The relative durabilities of SiO{sub 2}, obsidians, basalts, nuclear waste glasses, medieval window glasses, and a frit glass were determined in tuffaceous groundwater, basaltic groundwater, WIPP-A brine, and Permian-A brine using the monolithic MCC-1 durability test. For all the groundwaters, the free energy of hydration, calculated from the glass composition and the final experimental pH, was linearly related to the logarithm of the measured silica concentration. The linear equation was identical to that observed previously for these glasses during MCC-1 testing in deionized water. In the groundwater-dominated MCC-1 experiments, the pH values for all the glasses tested appeared to be buffered by the groundwater-precipitate chemistry. The behavior of poorly durable glasses demonstrated that the silica release is a function of the ionic strength of the solution. The ionic strength, in turn, reflects the effect of the groundwater chemistry on the pH. Using the hydration thermodynamic model, nuclear waste glass durability in saturated repository environments can be predicted from the glass composition and the groundwater and the groundwater pH. 47 refs., 3 figs. 1 tab.

  20. A review of polymer electrolyte membrane fuel cell durability test protocols

    NASA Astrophysics Data System (ADS)

    Yuan, Xiao-Zi; Li, Hui; Zhang, Shengsheng; Martin, Jonathan; Wang, Haijiang

    Durability is one of the major barriers to polymer electrolyte membrane fuel cells (PEMFCs) being accepted as a commercially viable product. It is therefore important to understand their degradation phenomena and analyze degradation mechanisms from the component level to the cell and stack level so that novel component materials can be developed and novel designs for cells/stacks can be achieved to mitigate insufficient fuel cell durability. It is generally impractical and costly to operate a fuel cell under its normal conditions for several thousand hours, so accelerated test methods are preferred to facilitate rapid learning about key durability issues. Based on the US Department of Energy (DOE) and US Fuel Cell Council (USFCC) accelerated test protocols, as well as degradation tests performed by researchers and published in the literature, we review degradation test protocols at both component and cell/stack levels (driving cycles), aiming to gather the available information on accelerated test methods and degradation test protocols for PEMFCs, and thereby provide practitioners with a useful toolbox to study durability issues. These protocols help prevent the prolonged test periods and high costs associated with real lifetime tests, assess the performance and durability of PEMFC components, and ensure that the generated data can be compared.

  1. Beta cloth durability assessment for Space Station Freedom (SSF) Multi-Layer Insulation (MLI) blanket covers

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L.; Jacobs, Stephen; Le, Julie

    1993-01-01

    MLI blankets for the Space Station Freedom (SSF) must comply with general program requirements and recommendations for long life and durability in the low-Earth orbit (LEO) environment. Atomic oxygen and solar ultraviolet/vacuum ultraviolet are the most important factors in the SSF natural environment which affect materials life. Two types of Beta cloth (Teflon coated woven glass fabric), which had been proposed as MLI blanket covers, were tested for long-term durability in the LEO environment. General resistance to atomic oxygen attack and permeation were evaluated in the high velocity atomic oxygen beam system at Los Alamos National Laboratories. Long-term exposure to the LEO environment was simulated in the laboratory using a radio frequency oxygen plasma asher. The plasma asher treated Beta cloth specimens were tested for thermo-optical properties and mechanical durability. Space exposure data from the Long Duration Exposure Facility and the Intelsat Solar Array Coupon were also used in the durability assessment. Beta cloth fabricated to Rockwell specification MBO 135-027 (Chemglas 250) was shown to have acceptable durability for general use as an MLI blanket cover material in the LEO environment while Sheldahl G414500 should be used only in locations which are protected from direct Ram atomic oxygen.

  2. Improving the durability of a drag-reducing nanocoating by enhancing its mechanical stability.

    PubMed

    Cheng, Mengjiao; Zhang, Songsong; Dong, Hongyu; Han, Shihui; Wei, Hao; Shi, Feng

    2015-02-25

    The durability of superhydrophobic surface is a major problem to restrict industrial application of superhydrophobic materials from laboratory research, which can be attributed to a more general issue of mechanical stability for superhydrophobic coatings. Therefore, in order to handle this issue, we have fabricated a mechanically stable drag-reducing coating composed of elastic polydimethylsiloxane (PDMS) and hydrophobic copper particles on model ships, which can resist mechanical abrasion and has displayed a durable drag-reducing effect. In comparison with normal Au superhydrophobic coatings, the as-prepared PDMS/copper coatings showed durable drag reduction performance with a similar drag-reducing rate before (26%) and after (24%) mechanical abrasion. The mechanism for the enhanced mechanical stability and maintained drag reduction of the superhydrophobic surfaces was investigated through characterizations of surface morphology, surface wettability, and water adhesive force evaluation before and after abrasion. This is the first demonstration to realize the application of durable drag reduction by improving the mechanical stability of superhydrophobic coatings. We do believe that superhydrophobic surfaces with good resistance to mechanical abrasion or scratching may draw wide attention and gain significant applications with durable drag-reducing properties.

  3. Low Earth orbit atomic oxygen simulation for durability evaluation of solar reflector surfaces

    NASA Technical Reports Server (NTRS)

    Degroh, Kim K.; Banks, Bruce A.

    1992-01-01

    To evaluate the performance and durability of solar reflector surfaces in the atomic oxygen environment typical of low Earth orbit (LEO), one must expose the reflector surface either directly to LEO or to ground-laboratory atomic oxygen environments. Although actual LEO exposures are most desired, such opportunities are typically scarce, expensive, and of limited duration. As a result, ground-laboratory exposures must be relied upon as the most practical long-term durability evaluation technique. Plasma ashers are widely used as LEO simulation facilities by producing atomic oxygen environments for durability evaluation of potential spacecraft materials. Atomic oxygen arrival differs between ground and space exposure in that plasma asher exposure produces isotropic arrival and space solar tracking produces sweeping arrival. Differences in initial impact reaction probability occur, dependent upon the energy and species existing in these environments. Due to the variations in ground-laboratory and space atomic oxygen, quantification of in-space performance based on plasma asher testing is not straightforward. The various atomic oxygen interactions that can occur with reflector surfaces, such as undercutting in organic substrates at protective coating defect sites, ground-laboratory techniques recommended for evaluating the atomic oxygen durability of reflectors based on asher exposures, and computational techniques which make use of ground-laboratory atomic oxygen exposure to predict in-space LEO durability are addressed.

  4. DURABILITY EVALUATION AND PRODUCTION OF MANUFACTURED AGGREGATES FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    M. M. Wu

    2005-02-01

    Under the cooperative agreement with DOE, the Research and Development Department of CONSOL Energy (CONSOL R&D), teamed with Universal Aggregates, LLC, to conduct a systematic study of the durability of aggregates manufactured using a variety of flue gas desulfurization (FGD), fluidized-bed combustion (FBC) and fly ash specimens with different chemical and physical properties and under different freeze/thaw, wet/dry and long-term natural weathering conditions. The objectives of the study are to establish the relationships among the durability and characteristics of FGD material, FBC ash and fly ash, and to identify the causes of durability problems, and, ultimately, to increase the utilization of FGD material, FBC ash and fly ash as a construction material. Manufactured aggregates made from FGD material, FBC ash and fly ash, and products made from those manufactured aggregates were used in the study. The project is divided into the following activities: sample collection and characterization; characterization and preparation of manufactured aggregates; determination of durability characteristics of manufactured aggregates; preparation and determination of durability characteristics of manufactured aggregate products; and data evaluation and reporting.

  5. Measurement of Exterior Foundation Insulation to Assess Durability in Energy-Saving Performance

    SciTech Connect

    Kehrer, Manfred; Christian, Jeff

    2012-04-01

    The foundation of a house is a sometimes ignored component of the building because of its low visibility. It is increasingly evident, however, that attention to good foundation design and construction significantly benefits the homeowner and the builder by mitigating future problems. Good foundation design and construction practice involves not only insulating to save energy but also providing effective structural design as well as moisture, termite, and radon control techniques as appropriate. Energy efficiency in housing is augmented by use of exterior slab and basement insulation, but high moisture content in the insulation material has led to concerns about its durability. The activity under this task was to extract six different exterior insulation systems that were characterized at installation and have been in the ground for 9 months to 15 years. R-value and moisture content were measured and inspections conducted for evidence of termite intrusion or deterioration. Based on the results, the durability of the various systems has been documented and assessments made of which systems appear to be best practice. Heat flux and temperature measurement data had been archived for some of the exterior insulation tests, thereby providing a unique opportunity to assess energy-saving performance and durability over the long term. The results show that the durability of foundation insulation systems depends on insulation type as well as on foundation type and local boundary conditions, the latter of which may have a marked influence on the durability of energy-saving performance.

  6. Healthy Aging

    MedlinePlus

    ... About Us Contact Us Text size | Print | Healthy Aging This information in Spanish ( en español ) A healthy ... Aging email updates. Enter email address Submit Healthy Aging news Accessibility | Privacy policy | Disclaimers | FOIA | Link to ...

  7. Healthy Aging

    MedlinePlus

    ... A Change Contrast print sign up Share Healthy Aging This category offers tips on how to stay ... with Smell Problems with Taste Skin Care and Aging Sleep and Aging Taking Medicines Talking with Your ...

  8. Public Sector Impasse Procedures.

    ERIC Educational Resources Information Center

    Vadakin, James C.

    The subject of collective bargaining negotiation impasse procedures in the public sector, which includes public school systems, is a broad one. In this speech, the author introduces the various procedures, explains how they are used, and lists their advantages and disadvantages. Procedures discussed are mediation, fact-finding, arbitration,…

  9. Chemical durability of soda-lime-aluminosilicate glass for radioactive waste vitrification

    SciTech Connect

    Eppler, F.H.; Yim, M.S.

    1998-09-01

    Vitrification has been identified as one of the most viable waste treatment alternatives for nuclear waste disposal. Currently, the most popular glass compositions being selected for vitrification are the borosilicate family of glasses. Another popular type that has been around in glass industry is the soda-lime-silicate variety, which has often been characterized as the least durable and a poor candidate for radioactive waste vitrification. By replacing the boron constituent with a cheaper substitute, such as silica, the cost of vitrification processing can be reduced. At the same time, addition of network intermediates such as Al{sub 2}O{sub 3} to the glass composition increases the environmental durability of the glass. The objective of this study is to examine the ability of the soda-lime-aluminosilicate glass as an alternative vitrification tool for the disposal of radioactive waste and to investigate the sensitivity of product chemical durability to variations in composition.

  10. New Accelerated Testing and Lifetime Modeling Methods Promise Faster Development of More Durable MEAs

    SciTech Connect

    Pierpont, D. M.; Hicks, M. T.; Turner, P. L.; Watschke, T. M.

    2005-11-01

    For the successful commercialization of fuel cell technology, it is imperative that membrane electrode assembly (MEA) durability is understood and quantified. MEA lifetimes of 40,000 hours remain a key target for stationary power applications. Since it is impractical to wait 40,000 hours for durability results, it is critical to learn as much information as possible in as short a time period as possible to determine if an MEA sample will survive past its lifetime target. Consequently, 3M has utilized accelerated testing and statistical lifetime modeling tools to develop a methodology for evaluating MEA lifetime. Construction and implementation of a multi-cell test stand have allowed for multiple accelerated tests and stronger statistical data for learning about durability.

  11. Activity and Durability of Iridium Nanoparticles in the Oxygen Evolution Reaction

    DOE PAGES

    Alia, Shaun M.; Rasimick, Brian; Ngo, Chilan; Neyerlin, K. C.; Kocha, Shyam S.; Pylypenko, Svitlana; Xu, Hui; Pivovar, Bryan S.

    2016-07-15

    Unsupported iridium (Ir) nanoparticles, that serve as standard oxygen evolution reaction (OER) catalysts in acidic electrolyzers, were investigated for electrochemical performance and durability in rotating disk electrode (RDE) half-cells. Fixed potential holds and potential cycling were applied to probe the durability of Ir nanoparticles, and performance losses were found to be driven by particle growth (coarsening) at moderate potential (1.4 to 1.6 V) and Ir dissolution at higher potential (>/=1.8 V). Several different commercially available samples were evaluated and standardized conditions for performance comparison are reported. In conclusion, the electrocatalyst RDE results have also been compared to results obtained formore » performance and durability in electrolysis cells.« less

  12. The Study on the Durability of Submerged Structure Displacement due to Concrete Failure

    NASA Astrophysics Data System (ADS)

    Mohd, M.; Zainon, O.; Rasib, A. W.; Majid, Z.

    2016-09-01

    Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

  13. Carbon nanocages: A new support material for Pt catalyst with remarkably high durability

    PubMed Central

    Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

    2014-01-01

    Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology, and corrosion of carbon support materials of current catalysts is the main cause. Here, we describe the finding of remarkably high durability with the use of a novel support material. This material is based on hollow carbon nanocages developed with a high degree of graphitization and concurrent nitrogen doping for oxidation resistance enhancement, uniform deposition of fine Pt particles, and strong Pt-support interaction. Accelerated degradation testing shows that such designed catalyst possesses a superior electrochemical activity and long-term stability for both hydrogen oxidation and oxygen reduction relative to industry benchmarks of current catalysts. Further testing under conditions of practical fuel cell operation reveals almost no degradation over long-term cycling. Such a catalyst of high activity, particularly, high durability, opens the door for the next-generation PEMFC for “real world” application. PMID:24658614

  14. Durability of a continuous strand mat polymeric composite for automotive structural applications

    SciTech Connect

    Corum, J.M.; McCoy, H.E. Jr.; Ruggles, M.B.; Simpson, W.A. Jr.

    1995-12-31

    A key unanswered question that must be addressed before polymeric composites will be widely used in automotive structural components is their durability. Major durability issues are the effects of cyclic loadings, creep, automotive environments, and low-energy impacts on dimensional stability, strength, and stiffness. The U.S. Department of Energy is sponsoring a project at Oak Ridge National Laboratory to address these issues and to develop, in cooperation with the Automotive Composites Consortium, experimentally based, durability driven, design guidelines. The initial reference material is an isocyanurate reinforced with a continuous strand, swirl glass mat. This paper describes the basic deformation and failure behavior of the reference material, and it presents test results illustrating the property degradations caused by loading, time, and environmental effects. The importance of characterizing and understanding damage and how it leads to failure is also discussed. The results presented are from the initial phases of an ongoing project. The ongoing effort and plans are briefly described.

  15. Mixed hydrocarbon/fluoropolymer membrane/ionomer MEAs for durability studies

    SciTech Connect

    Li, Bo; Kim, Yu Seung; Mukundan, Rangachary; Borup, Rodney L; Wilson, Mahlon S; Welch, Cynthia; Fenton, James

    2010-01-01

    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. Commercial viability depends on improving the durability of the fuel cell components to increase the system reliability. The aim of this work is to separate ionomer degradation from membrane degradation via mixed membrane/ionomer MEA experiments. The challenges of mixed MEA fabrication due to the incompatibility of the membrane and the electrode are addressed. OCV accelerated testing experiment (AST) were performed. Development of in situ diagnostics and unique experiments to characterize the performance and properties of the ionomer in the electrode as a function of time is reported. These measurements, along with extensive ex situ and post-mortem characterization, can delineate the degradation mechanisms in order to develop more durable fuel cells and fuel cell components.

  16. High durability and low toxicity antimicrobial coatings fabricated by quaternary ammonium silane copolymers.

    PubMed

    Li, Hairui; Bao, Hongqian; Bok, Ke Xin; Lee, Chi-Ying; Li, Bo; Zin, Melvin T; Kang, Lifeng

    2016-02-01

    Adhesion and subsequent growth of microorganisms on material surfaces are a major concern in many biomedical applications. Currently, various polymers are immobilized on material surfaces to prevent microbial colonization. However, there are several challenges with regard to the coating materials, including their inability to kill microorganisms, complexity of surface grafting, limited durability and toxicity towards humans. To address these challenges, we synthesize a novel quaternary ammonium silane (QAS) antimicrobial copolymer to confer the antimicrobial effect via a simple thermal-curing coating process. The QAS copolymers were less toxic to 3 human cell lines than a commercial antimicrobial QAS monomeric agent, namely, dimethyloctadecyl[3-(trimethoxysilyl) propyl]ammonium chloride (DTPAC). Moreover, the QAS coatings demonstrated superior antimicrobial efficacy and durability than those of the DTPAC coatings. In conclusion, the novel QAS copolymers are useful to prevent substrates from microbial infections, yet with low toxicity to humans and long durability. In addition, the synthetic process is potentially scalable for industrial applications.

  17. Impact of Fuel Metal Impurities on the Durability of a Light-Duty Diesel Aftertreatment System

    SciTech Connect

    Williams, A.; Burton, J.; McCormick, R. L.; Toops, T.; Wereszczak, A. A.; Fox, E. E.; Lance, M. J.; Cavataio, G.; Dobson, D.; Warner, J.; Brezny, R.; Nguyen, K.; Brookshear, D. W.

    2013-04-01

    Alkali and alkaline earth metal impurities found in diesel fuels are potential poisons for diesel exhaust catalysts. A set of diesel engine production exhaust systems was aged to 150,000 miles. These exhaust systems included a diesel oxidation catalyst, selective catalytic reduction (SCR) catalyst, and diesel particulate filter (DPF). Four separate exhaust systems were aged, each with a different fuel: ultralow sulfur diesel containing no measureable metals, B20 (a common biodiesel blend) containing sodium, B20 containing potassium, and B20 containing calcium, which were selected to simulate the maximum allowable levels in B100 according to ASTM D6751. Analysis included Federal Test Procedure emissions testing, bench-flow reactor testing of catalyst cores, electron probe microanalysis (EPMA), and measurement of thermo-mechanical properties of the DPFs. EPMA imaging found that the sodium and potassium penetrated into the washcoat, while calcium remained on the surface. Bench-flow reactor experiments were used to measure the standard nitrogen oxide (NOx) conversion, ammonia storage, and ammonia oxidation for each of the aged SCR catalysts. Vehicle emissions tests were conducted with each of the aged catalyst systems using a chassis dynamometer. The vehicle successfully passed the 0.2 gram/mile NOx emission standard with each of the four aged exhaust systems.

  18. Durable resistance: A key to sustainable management of pathogens and pests

    PubMed Central

    Mundt, Christopher C.

    2014-01-01

    This review briefly addresses what has been learned about resistance durability in recent years, as well as the questions that still remain. Molecular analyses of major gene interactions have potential to contribute to both breeding for resistance and improved understanding of virulence impacts on pathogen fitness. Though the molecular basis of quantitative resistance is less clear substantial evidence has accumulated for the relative simplicity of inheritance. There is increasing evidence for specific interactions with quantitative resistance, though implications o this for durability are still unknown. Mechanisms by which resistance gene pyramids contribute to durability remain elusive, though ideas have been generated for identifying gene combinations that may be more durable. Though cultivar mixtures and related approaches have been used successfully, identifying the diseases and conditions that are most conducive to the use of diversity has been surprisingly difficult, and the selective influence of diversity on pathogen populations is complex. The importance of considering resistance durability in a landscape context has received increasing emphasis and is an important future area of research. Experimental systems are being developed to test resistance gene deployment strategies that previously could be addressed only with logic and observation. The value of molecular markers for identifying and pyramiding major genes is quite clear, but the successful use of quantitative trait loci (QTL) for marker-assisted selection of quantitative resistance will depend greatly on the degree to which the identified QTL are expressed in different genetic backgrounds. Transgenic approaches will likely provide opportunities for control of some recalcitrant pathogens, though issues of durability for transgenes are likely to be no different than other genes for resistance. The need for high quality phenotypic analysis and screening methodologies is a priority, and field

  19. Prediction of glass durability as a function of glass composition and test conditions: Thermodynamics and kinetics

    SciTech Connect

    Jantzen, C M

    1988-01-01

    The long-term durability of nuclear waste glasses can be predicted by comparing their performance to natural and ancient glasses. Glass durability is a function of the kinetic and thermodynamic stability of glass in solution. The relationship between the kinetic and thermodynamic aspects of glass durability can be understood when the relative contributions of glass composition and imposed test conditions are delineated. Glass durability has been shown to be a function of the thermodynamic hydration free energy which can be calculated from the glass composition. Hydration thermodynamics also furnishes a quantitative frame of reference to understand how various test parameters affect glass durability. Linear relationships have been determined between the logarithmic extent of hydration and the calculated hydration free energy for several different test geometries. Different test conditions result in different kinetic reactivity parameters such as the exposed glass surface area (SA), the leachant solution volume (V), and the length of time that the glass is in the leachant (t). Leachate concentrations are known to be a function of the kinetic test parameter (SAV)t. The relative durabilities of glasses, including pure silica, obsidians, nuclear waste glasses, medieval window glasses, and frit glasses define a plane in three dimensional ..delta..G/sub hyd/-concentration-(SAV)t space. At constant kinetic conditions, e.g., test geometry and test duration, the three dimensional plane is intersected at constant (SAV)t and the ..delta..G/sub hyd/-concentration plots have similar slopes. The slope represents the natural logarithm of the theoretical slope, (12.303 RT), for the rate of glass dissolution. 53 refs., 4 figs.

  20. Durability-Based Design Guide for an Automotive Structural Composite: Part 2. Background Data and Models

    SciTech Connect

    Corum, J.M.; Battiste, R.L.; Brinkman, C.R.; Ren, W.; Ruggles, M.B.; Weitsman, Y.J.; Yahr, G.T.

    1998-02-01

    This background report is a companion to the document entitled ''Durability-Based Design Criteria for an Automotive Structural Composite: Part 1. Design Rules'' (ORNL-6930). The rules and the supporting material characterization and modeling efforts described here are the result of a U.S. Department of Energy Advanced Automotive Materials project entitled ''Durability of Lightweight Composite Structures.'' The overall goal of the project is to develop experimentally based, durability-driven design guidelines for automotive structural composites. The project is closely coordinated with the Automotive Composites Consortium (ACC). The initial reference material addressed by the rules and this background report was chosen and supplied by ACC. The material is a structural reaction injection-molded isocyanurate (urethane), reinforced with continuous-strand, swirl-mat, E-glass fibers. This report consists of 16 position papers, each summarizing the observations and results of a key area of investigation carried out to provide the basis for the durability-based design guide. The durability issues addressed include the effects of cyclic and sustained loadings, temperature, automotive fluids, vibrations, and low-energy impacts (e.g., tool drops and roadway kickups) on deformation, strength, and stiffness. The position papers cover these durability issues. Topics include (1) tensile, compressive, shear, and flexural properties; (2) creep and creep rupture; (3) cyclic fatigue; (4) the effects of temperature, environment, and prior loadings; (5) a multiaxial strength criterion; (6) impact damage and damage tolerance design; (7) stress concentrations; (8) a damage-based predictive model for time-dependent deformations; (9) confirmatory subscale component tests; and (10) damage development and growth observations.

  1. Developing policies and procedures.

    PubMed

    Randolph, Susan A

    2006-11-01

    The development of policies and procedures is an integral part of the occupational health nurse's role. Policies and procedures serve as the foundation for the occupational health service and are based on its vision, mission, culture, and values. The design and layout selected for the policies and procedures should be simple, consistent, and easy to use. The same format should be used for all existing and new policies and procedures. Policies and procedures should be reviewed periodically based on a specified time frame (i.e., annually). However, some policies may require a more frequent review if they involve rapidly changing external standards, ethical issues, or emerging exposures. PMID:17124968

  2. Recent Development of Durable and Self-Healing Surfaces with Special Wettability.

    PubMed

    Chen, Kunlin; Wu, Yi; Zhou, Shuxue; Wu, Limin

    2016-03-01

    Artificial special wetting surfaces have drawn much interest due to their important applications in many fields. Nevertheless, tremendous challenges still remain for the fabrication of wetting surfaces with durable and self-healing properties. Here, recent progress of durable, self-healing wetting surfaces is highlighted by discussing the fabrications of several typical wetting surfaces including superhydrophobic surfaces, superamphiphobic surfaces, underwater superoleophobic surfaces, and high hydrophilic antifouling surfaces based on expertise and related research experience. To conclude, some perspectives on the future research and development of these special wetting surfaces are presented.

  3. Performance, durability and low temperature evaluation of sunflower oil as a diesel fuel extender

    SciTech Connect

    Baranescu, R.A.; Lusco, J.J.

    1982-01-01

    The paper presents the results of a research project to evaluate performance and durability of direct injection turbocharged diesel engines using sunflower oil and blends thereof. Alcaline refined sunflower oil and three different blends of sunflower oil and diesel fuel were comparatively tested against No. 2 diesel fuel for: physical and chemical characteristics, fuel injection system performance, short term engine performance, propensity to nozzle deposits buildup, limited durability operation and low temperature starting capability. Results are presented for the various phases of the project and correlations between the fuel characteristics and engine accept-ability are discussed. 19 figures, 2 tables.

  4. Atomic Oxygen Durability Evaluation of Protected Polymers Using Thermal Energy Plasma Systems

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Degroh, Kim K.; Stidham, Curtis R.; Gebauer, Linda; Lamoreaux, Cynthia M.

    1995-01-01

    The durability evaluation of protected polymers intended for use in low Earth orbit (LEO) has necessitated the use of large-area, high-fluence, atomic oxygen exposure systems. Two thermal energy atomic oxygen exposure systems which are frequently used for such evaluations are radio frequency (RF) plasma ashers and electron cyclotron resonance plasma sources. Plasma source testing practices such as ample preparation, effective fluence prediction, atomic oxygen flux determination, erosion measurement, operational considerations, and erosion yield measurements are presented. Issues which influence the prediction of in-space durability based on ground laboratory thermal energy plasma system testing are also addressed.

  5. Recent Development of Durable and Self-Healing Surfaces with Special Wettability.

    PubMed

    Chen, Kunlin; Wu, Yi; Zhou, Shuxue; Wu, Limin

    2016-03-01

    Artificial special wetting surfaces have drawn much interest due to their important applications in many fields. Nevertheless, tremendous challenges still remain for the fabrication of wetting surfaces with durable and self-healing properties. Here, recent progress of durable, self-healing wetting surfaces is highlighted by discussing the fabrications of several typical wetting surfaces including superhydrophobic surfaces, superamphiphobic surfaces, underwater superoleophobic surfaces, and high hydrophilic antifouling surfaces based on expertise and related research experience. To conclude, some perspectives on the future research and development of these special wetting surfaces are presented. PMID:26833559

  6. Energy efficient one-pot synthesis of durable superhydrophobic coating through nylon micro-rods

    NASA Astrophysics Data System (ADS)

    Simovich, T.; Wu, A. H.; Lamb, R. N.

    2014-03-01

    A durable and superhydrophobic coating was fabricated at room temperature through encapsulating nylon micro-rods in a hydrophobic silica shell. This was achieved through the precipitation of miniemulsified nylon under high shear to generate micro-rods with high aspect ratio in the presence of methyltrimethoxysilane. The resultant coating structure resembles a network of highly entangled micro-rods that give rise to both surface roughness and hydrophobicity, resulting in contact angles greater than 155°. The embedded nylon polymer within the micro-rods imparts significant mechanical durability to the surface, resulting in a coating hardness of 2H using the pencil hardness test.

  7. Chemical durability and degradation mechanisms of HT9 based alloy waste forms with variable Zr content

    SciTech Connect

    Olson, L. N.

    2015-10-30

    In Corrosion studies were undertaken on alloy waste forms that can result from advanced electrometallurgical processing techniques to better classify their durability and degradation mechanisms. The waste forms were based on the RAW3-(URe) composition, consisting primarily of HT9 steel and other elemental additions to simulate nuclear fuel reprocessing byproducts. The solution conditions of the corrosion studies were taken from an electrochemical testing protocol, and meant to simulate conditions in a repository. The alloys durability was examined in alkaline and acidic brines.

  8. Recommended Minimum Test Requirements and Test Methods for Assessing Durability of Random-Glass-Fiber Composites

    SciTech Connect

    Battiste, R.L.; Corum, J.M.; Ren, W.; Ruggles, M.B.

    1999-06-01

    This report provides recommended minimum test requirements are suggested test methods for establishing the durability properties and characteristics of candidate random-glass-fiber polymeric composites for automotive structural applications. The recommendations and suggestions are based on experience and results developed at Oak Ridge National Laboratory (ORNL) under a US Department of Energy Advanced Automotive Materials project entitled ''Durability of Lightweight Composite Structures,'' which is closely coordinated with the Automotive Composites Consortium. The report is intended as an aid to suppliers offering new structural composites for automotive applications and to testing organizations that are called on to characterize the composites.

  9. 5 CFR 9901.515 - Competitive examining procedures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... selection procedures (i.e., category rating). Components must decide which procedures to use prior to..., age, gender, national origin, political affiliation, disability, sexual orientation, marital or family..., procedures, and guidance will be consistent with the “Uniform Guidelines on Employee Selection...

  10. Investigation of the impact of rain and particle erosion on rotor blade aerodynamics with an erosion test facility to enhancing the rotor blade performance and durability

    NASA Astrophysics Data System (ADS)

    Liersch, J.; Michael, J.

    2014-06-01

    During their operational life span of around 20 years, the individual components of a wind turbine, especially the rotor blades, are exposed to extreme environmental influences. This is the result of the continuous exposure of wind turbines to the elements and of particularly high rotor blade tip speeds, which exceed a velocity of 90 m/s. These effects result in leading edge erosion. Rotor blades are therefore protected by special coating systems, e.g. varnishes and foils. The durability of those surface coatings varies depending on the location of the wind turbine and often proves to be insufficient. Additionally, there is no standardised test procedure for the evaluation of the durability and protective effect of the coating materials under the highly erosive conditions at the location of the wind turbines. In the course of this project, we will develop a testing procedure to evaluate the erosion of coating materials on actual leading edges of rotor blades, which will be applied in a test facility. The test rig will be capable of simulating a realistic application of rain and sand to gauge the effects of erosion. During the application, two test objects can be tested simultaneously. The geometry of the test objects will be adapted to represent that of real rotor blade tips. In order to generate comparable and transferable results, several challenges have to be met during the implementation, especially the realistic reproduction of environmental influences and the corrosion damage mechanism. In this regard, the duration of the test procedure is very important because a time lapse factor of 100-260 is intended. An operation of 20 years can thereby be simulated within 4 to 10 weeks.

  11. Peroral endoscopic myotomy: An emerging minimally invasive procedure for achalasia

    PubMed Central

    Vigneswaran, Yalini; Ujiki, Michael B

    2015-01-01

    Peroral endoscopic myotomy (POEM) is an emerging minimally invasive procedure for the treatment of achalasia. Due to the improvements in endoscopic technology and techniques, this procedure allows for submucosal tunneling to safely endoscopically create a myotomy across the hypertensive lower esophageal sphincter. In the hands of skilled operators and experienced centers, the most common complications of this procedure are related to insufflation and accumulation of gas in the chest and abdominal cavities with relatively low risks of devastating complications such as perforation or delayed bleeding. Several centers worldwide have demonstrated the feasibility of this procedure in not only early achalasia but also other indications such as redo myotomy, sigmoid esophagus and spastic esophagus. Short-term outcomes have showed great clinical efficacy comparable to laparoscopic Heller myotomy (LHM). Concerns related to postoperative gastroesophageal reflux remain, however several groups have demonstrated comparable clinical and objective measures of reflux to LHM. Although long-term outcomes are necessary to better understand durability of the procedure, POEM appears to be a promising new procedure. PMID:26468336

  12. Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

    NASA Technical Reports Server (NTRS)

    Liebert, C. H.; Jacobs, R. E.; Stecura, S.; Morse, C. R.

    1976-01-01

    Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

  13. 42 CFR 409.50 - Coinsurance for durable medical equipment (DME) furnished as a home health service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Coinsurance for durable medical equipment (DME) furnished as a home health service. 409.50 Section 409.50 Public Health CENTERS FOR MEDICARE & MEDICAID... Services Under Hospital Insurance § 409.50 Coinsurance for durable medical equipment (DME) furnished as...

  14. Moving Into the Third Age.

    ERIC Educational Resources Information Center

    Journal of Physical Education, Recreation & Dance, 1986

    1986-01-01

    Twelve articles on aging address the needs of older adults. Discussed are effects of physical activity on the aging process, physical assessment procedures, nutrition, dance, aerobics, fitness needs, recreation needs, and even in-home activities for seniors. A listing of resource agencies, books, records, cassettes, journals and indexes is…

  15. Modeling the Rate-Dependent Durability of Reduced-Ag SAC Interconnects for Area Array Packages Under Torsion Loads

    NASA Astrophysics Data System (ADS)

    Srinivas, Vikram; Menon, Sandeep; Osterman, Michael; Pecht, Michael G.

    2013-08-01

    Solder durability models frequently focus on the applied strain range; however, the rate of applied loading, or strain rate, is also important. In this study, an approach to incorporate strain rate dependency into durability estimation for solder interconnects is examined. Failure data were collected for SAC105 solder ball grid arrays assembled with SAC305 solder that were subjected to displacement-controlled torsion loads. Strain-rate-dependent (Johnson-Cook model) and strain-rate-independent elastic-plastic properties were used to model the solders in finite-element simulation. Test data were then used to extract damage model constants for the reduced-Ag SAC solder. A generalized Coffin-Manson damage model was used to estimate the durability. The mechanical fatigue durability curve for reduced-silver SAC solder was generated and compared with durability curves for SAC305 and Sn-Pb from the literature.

  16. Laparoscopic reversal of Hartmann's procedure.

    PubMed

    Fiscon, Valentino; Portale, Giuseppe; Mazzeo, Antonio; Migliorini, Giovanni; Frigo, Flavio

    2014-12-01

    Reestablishing continuity after a Hartmann's procedure is considered a major surgical procedure with high morbidity/mortality. The aim of this study was to assess the short-/long-term outcome of laparoscopic restoration of bowel continuity after HP. A prospectively collected database of colorectal laparoscopic procedures (>800) performed between June 2005 and June 2013 was used to identify 20 consecutive patients who had undergone laparoscopic reversal of Hartmann's procedure (LHR). Median age was 65.4. Ten patients (50 %) had undergone surgery for perforated diverticulitis, 3 (15 %) for cancer, and 7 (35 %) for other reasons (volvulus, posttraumatic perforation, and sigmoid perforation from foreign body). Previous HP had been performed laparoscopically in only 3 patients. Median operative time was 162.5 min. All the procedures were completed laparoscopically. Intraoperative complication rate was nil. Post-operative mortality and morbidity were respectively 0 and 10 % (1 pneumonia, 1 bowel obstruction from post-anastomotic stenosis which required resection and redo of the anastomosis). Median time to first flatus was 3 days, to normal diet 5 days. Median hospital stay was 9 days without readmissions. We followed up the patients for a median of 44 months: when asked, all 20 (100 %) said they would undergo the operation (LHR) again; 3 (15 %) had been re-operated of laparoscopic mesh repair for incisional hernia. When performed by experienced surgeons, LHR is a feasible, safe, reproducible operation, which allows early return of bowel function, early discharge and fast return to work for the patient. It has a low morbidity rate.

  17. Computer Analysis of Durability and Leakproofness of Multilateral Junction of Wells

    NASA Astrophysics Data System (ADS)

    Syzrantseva, K.; Dvoynikov, M.

    2016-08-01

    The paper considers method of computer simulation of well multilateral junctions corresponding to TAML Level-4. The base stages of algorithm of stress-strain condition calculation of cased main and side pipes are described. Durability of junction depending on internal pressure is established in a kind of functional dependences. The influence of side pipe thickness and whipstock angle on junction deformation is researched.

  18. First-order model for durability of Hanford waste glasses as a function of composition

    SciTech Connect

    Hrma, P.; Piepel, G.F.; Schweiger, M.J.; Smith, D.E.

    1992-04-01

    Two standard chemical durability tests, the static leach test MCC-1 and product consistency test PCT, were conducted on simulated borosilicate glasses that encompass the expected range of compositions to be produced in the Hanford Waste Vitrification Plant (HWVP). A first-order empirical model was fitted to the data from each test method. The results indicate that glass durability is increased by addition of Al{sub 2}O{sub 3}, moderately increased by addition of ZrO{sub 2} and SiO{sub 2}, and decreased by addition of Li{sub 2}O, Na{sub 2}O, B{sub 2}O{sub 3}, and MgO. Addition of Fe{sub 2}O{sub 3} and CaO produce an indifferent or reducing effect on durability according to the test method. This behavior and a statistically significant lack of fit are attributed to the effects of multiple chemical reactions occurring during glass-water interaction. Liquid-liquid immiscibility is suspected to be responsible for extremely low durability of some glasses.

  19. Characterization of sensor performance and durability for structural health monitoring systems

    NASA Astrophysics Data System (ADS)

    Blackshire, James L.; Giurgiutiu, Victor; Cooney, Adam; Doane, James

    2005-05-01

    A key question that needs to be addressed and answered with regard to successfully implementing Structural Health Monitoring technologies in Air Force systems involves the long-term operability, durability, and survivability of integrated sensor systems and their associated hardware. Whether a sensor system is fully integrated within a structural material, or surface-bonded to the structure, a number of environmental and system level influences will tend to degrade the sensor system"s performance and durability over time. In this effort, an initial sensor durability study was undertaken to better understand the performance and degradation of piezo wafer active sensor (PWAS) systems under adverse mechanical, temperature, and moisture conditions. A novel displacement-field imaging approach was utilized to understand the vibration characteristics of PWAS transducers placed in accelerated vibration, temperature-cycling, and moisture-cycling conditions. The results showed damage in the form of PWAS sensor cracking events, bond degradation and failure, as well as indications of performance variation and reduction due to the accelerated exposure levels. Future activities will focus on identifying critical durability and survivability issues through advanced sensor modeling and additional accelerated testing efforts, with the ultimate goal of improving the robustness of health monitoring systems through improved sensor system design and packaging.

  20. Optical & Environmental Performance of Durable Silver Mirror Coatings Fabricated at LLNL

    SciTech Connect

    Wolfe, J; Sanders, D

    2004-03-05

    A Family of Durable Silver Mirror Designs has been fabricated at LLNL. We report here on the optical and environmental performance of the basic design, which can be cleaned with standard glass cleaner and cloth after months of exposure to outside atmosphere.