Carbon nanocages: a new support material for Pt catalyst with remarkably high durability.

PubMed

Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

2014-03-24

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.

Methods to determine long-term durability of Wisconsin aggregates.

DOT National Transportation Integrated Search

2013-02-01

Wisconsin uses approximately 10 to 11 million tons of aggregates annually in transportation infrastructure projects in the state. The quality of aggregates has a tremendous influence on the performance and durability of roadways and bridges. As sourc...

Long-Term Durability Analysis of a 100,000+ Hr Stirling Power Convertor Heater Head

NASA Technical Reports Server (NTRS)

Bartolotta, Paul A.; Bowman, Randy R.; Krause, David L.; Halford, Gary R.

2000-01-01

DOE and NASA have identified Stirling Radioisotope Power Systems (SRPS) as the power supply for deep space exploration missions the Europa Orbiter and Solar Probe. As a part of this effort, NASA has initiated a long-term durability project for critical hot section components of the Stirling power convertor to qualify flight hardware. This project will develop a life prediction methodology that utilizes short-term (t < 20,000 hr) test data to verify long-term (t > 100,000 hr) design life. The project consists of generating a materials database for the specific heat of alloy, evaluation of critical hermetic sealed joints, life model characterization, and model verification. This paper will describe the qualification methodology being developed and provide a status for this effort.

American Marriage in the Early Twenty-First Century

ERIC Educational Resources Information Center

Cherlin, Andrew J.

2005-01-01

During the past century the U.S. family system has seen vast changes--in marriage and divorce rates, cohabitation, childbearing, sexual behavior, and women's work outside the home. Andrew Cherlin reviews these historic changes, noting that marriage remains the most common living arrangement for raising children, but that children, especially poor…

Investigation of testing methods to determine long-term durability of Wisconsin aggregates.

DOT National Transportation Integrated Search

2013-01-01

Approximately 10 to 11 million tons of aggregates are utilized in transportation infrastructure projects in : Wisconsin annually. The quality of aggregates has a tremendous influence on the performance and durability : of roadways and bridges. In thi...

Survey of long-term durability of fiberglass reinforced plastic structures

NASA Technical Reports Server (NTRS)

Lieblein, S.

1981-01-01

Included are fluid containment vessels, marine structures, and aircraft components with up to 19 years of service. Correlations were obtained for the variation of static fatigue strength, cyclic fatigue strength, and residual burst strength for pressure vessels. In addition, data are presented for the effects of moisture on strength retention. Data variations were analyzed, and relationships and implications for testing are discussed. Change in strength properties for complete structures was examined for indications of the effects of environmental conditions such as moisture and outdoor exposure (ultraviolet radiation, weathering) on long term durability.

Durability and degradation of HT9 based alloy waste forms with variable Ni and Cr content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, L.

2016-12-31

Short-term electrochemical and long-term hybrid electrochemical corrosion tests were performed on alloy waste forms in reference aqueous solutions that bound postulated repository conditions. The alloy waste forms investigated represent candidate formulations that can be produced with advanced electrochemical treatment of used nuclear fuel. The studies helped to better understand the alloy waste form durability with differing concentrations of nickel and chromium, species that can be added to alloy waste forms to potentially increase their durability and decrease radionuclide release into the environment.

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.

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...

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

Evaluation of the Long-Term Durability of Joints Cut Using Early Entry Saws on Rigid Pavements

DOT National Transportation Integrated Search

2011-01-01

Early-entry sawing is an attractive operation to expedite the construction of jointed concrete pavements; however, : there are some concerns that the early-entry sawing may compromise the pavements long-term performance. The Illinois : Department ...

US-23 aggregate test road long-term performance evaluation : final report.

DOT National Transportation Integrated Search

2017-03-24

The US-23 Aggregate Test Road was constructed in 1992 with the main purpose to determine the influence of coarse : aggregate of varying frost susceptibility on long-term concrete durability. The pavement structure for the entire Test Road consists : ...

Long-term durability of the distal urethral polypropylene sling for the treatment of stress urinary incontinence: minimum 11-year followup.

PubMed

Rogo-Gupta, Lisa; Baxter, Z Chad; Le, Ngoc-Bich; Raz, Shlomo; Rodríguez, Larissa V

2012-11-01

We report on the long-term outcomes of the distal urethral polypropylene sling for stress urinary incontinence in a patient cohort that was closely followed and whose outcomes were reported at 1 and 5 years after surgery. We performed a prospective study of all consecutive patients who underwent a distal urethral polypropylene sling procedure between November 1999 and April 2000. The 1 and 5-year outcomes for this particular patient cohort were previously reported. At the minimum 11-year followup, outcome was determined by patient self-assessment including validated questionnaires. A total of 69 patients were followed prospectively and followup was obtained for 30. Of those lost to followup 10 were deceased and 5 were cognitively impaired. Mean patient age at followup was 73 years (range 40 to 97). More than 11 years after surgery 48% of patients reported no stress urinary incontinence symptoms and 63% were never bothered by stress urinary incontinence. Patients reported a mean overall symptom improvement of 64% compared to 81% at 5 years. Overall 82% of patients met the criteria for treatment success by symptom scores and 80% met the criteria by bother scores. The distal urethral polypropylene sling procedure has excellent long-term durability in the treatment of stress urinary incontinence, in addition to low morbidity and low cost as previously described. Eleven years after the procedure the majority of patients report symptom improvement. Nevertheless, many older patients are unable to participate in followup. When choosing an anti-incontinence procedure, durability should be considered in light of patient age given that the theoretical advantages of long-term durability are limited by cognitive decline and mortality. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Efficacy and durability of robotic Heller myotomy for achalasia: patient symptoms and satisfaction at long-term follow-up.

PubMed

Perry, Kyle A; Kanji, Aliyah; Drosdeck, Joseph M; Linn, John G; Chan, Anthony; Muscarella, Peter; Melvin, W Scott

2014-11-01

Laparoscopic Heller myotomy (LHM) has become the standard treatment for achalasia in the USA. Robot-assisted Heller myotomy (RHM) has emerged as an alternative approach due to improved visualization and fine motor control, but long-term follow-up studies have not been reported. We sought to report the long-term outcomes of RHM and compare them to those of LHM. A retrospective cohort study was performed for patients who underwent laparoscopic or RHM between 1995 and 2006. Long-term follow-up was performed via mail or telephone questionnaire. The primary outcome measure was durable relief of dysphagia without need for further intervention. Secondary outcomes included gastroesophageal reflux symptoms, disease-specific quality of life, and patient satisfaction with their operation. Seventy-five patients underwent laparoscopic (n = 19) or robotic (n = 56) myotomy during the study period. Long-term follow-up was obtained in 53 (71 %) patients with a median interval of 9 years. RHM was associated with a decreased mucosal injury rate (0 vs. 16 %, p = 0.01) and median hospital stay (1 vs. 2 days, p < 0.01) compared to conventional laparoscopy. All patients reported initial dysphagia relief, and 80 % required no further intervention. This did not differ between groups. Sixty-two percent required medications to control reflux symptoms at long-term follow-up, including 56 % following robotic myotomy and 80 % after laparoscopic myotomy (p = 0.27). Overall, 95 % of patients were satisfied with their operation, and 91 % would choose surgery again given the benefit of hindsight. There is a dearth of long-term follow-up data to support the effectiveness of RHM. This study demonstrates durable dysphagia relief in the vast majority of patients with a high degree of patient satisfaction and a low rate of esophageal mucosal injury. While a significant proportion of patients report reflux symptoms, these symptoms are well controlled with medical acid suppression.

Design of Pd/PANI/Pd sandwich-structured nanotube array catalysts with special shape effects and synergistic effects for ethanol electrooxidation.

PubMed

Wang, An-Liang; Xu, Han; Feng, Jin-Xian; Ding, Liang-Xin; Tong, Ye-Xiang; Li, Gao-Ren

2013-07-24

Low cost, high activity, and long-term durability are the main requirements for commercializing fuel cell electrocatalysts. Despite tremendous efforts, developing non-Pt anode electrocatalysts with high activity and long-term durability at low cost remains a significant technical challenge. Here we report a new type of hybrid Pd/PANI/Pd sandwich-structured nanotube array (SNTA) to exploit shape effects and synergistic effects of Pd-PANI composites for the oxidation of small organic molecules for direct alcohol fuel cells. These synthesized Pd/PANI/Pd SNTAs exhibit significantly improved electrocatalytic activity and durability compared with Pd NTAs and commercial Pd/C catalysts. The unique SNTAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Besides the merits of nanotube arrays, the improved electrocatalytic activity and durability are especially attributed to the special Pd/PANI/Pd sandwich-like nanostructures, which results in electron delocalization between Pd d orbitals and PANI π-conjugated ligands and in electron transfer from Pd to PANI.

Comprehensive evaluation of the long-term performance of rubberized pavement, phase II : the influence of rubber and asphalt interaction on mixture durability.

DOT National Transportation Integrated Search

2014-12-01

This project investigated the long-term performance of hot asphalt mixes containing crumb rubber : modifiers (CRM) added in dry or wet processes. A total of eight asphalt mixturesfour Porous : European Mixtures (PEMs) and four Stone Matrix Asphalt...

Development and evaluation of endurance test system for ventricular assist devices.

PubMed

Sumikura, Hirohito; Homma, Akihiko; Ohnuma, Kentaro; Taenaka, Yoshiyuki; Takewa, Yoshiaki; Mukaibayashi, Hiroshi; Katano, Kazuo; Tatsumi, Eisuke

2013-06-01

We developed a novel endurance test system that can arbitrarily set various circulatory conditions and has durability and stability for long-term continuous evaluation of ventricular assist devices (VADs), and we evaluated its fundamental performance and prolonged durability and stability. The circulation circuit of the present endurance test system consisted of a pulsatile pump with a small closed chamber (SCC), a closed chamber, a reservoir and an electromagnetic proportional valve. Two duckbill valves were mounted in the inlet and outlet of the pulsatile pump. The features of the circulation circuit are as follows: (1) the components of the circulation circuit consist of optimized industrial devices, giving durability; (2) the pulsatile pump can change the heart rate and stroke length (SL), as well as its compliance using the SCC. Therefore, the endurance test system can quantitatively reproduce various circulatory conditions. The range of reproducible circulatory conditions in the endurance test circuit was examined in terms of fundamental performance. Additionally, continuous operation for 6 months was performed in order to evaluate the durability and stability. The circulation circuit was able to set up a wide range of pressure and total flow conditions using the SCC and adjusting the pulsatile pump SL. The long-term continuous operation test demonstrated that stable, continuous operation for 6 months was possible without leakage or industrial device failure. The newly developed endurance test system demonstrated a wide range of reproducible circulatory conditions, durability and stability, and is a promising approach for evaluating the basic characteristics of VADs.

Subliminal words durably affect neuronal activity.

PubMed

Gaillard, Raphaël; Cohen, Laurent; Adam, Claude; Clemenceau, Stéphane; Hasboun, Dominique; Baulac, Michel; Willer, Jean-Claude; Dehaene, Stanislas; Naccache, Lionel

2007-10-08

Unconscious mental representations elicited by subliminal stimuli are marked by their fleeting lifetimes, usually below 1 s. Can such evanescent subliminal stimuli, nevertheless, lead to long-lasting learning? To date, evidence suggesting a long-term influence of briefly perceived stimuli on behaviour or brain activity is scarce and questionable. In this study, we used intracranial recordings to provide the first direct demonstration that unconsciously perceived subliminal words could exert long-lasting effects on neuronal signals. When repeating subliminal words over long interstimulus intervals, we observed electrophysiological repetition effects. These unconscious repetition effects suggest that the single presentation of a masked word can durably affect neural architecture.

Enhancing composite durability : using thermal treatments

Treesearch

Jerrold E. Winandy; W. Ramsay Smith

2007-01-01

The use of thermal treatments to enhance the moisture resistance and aboveground durability of solid wood materials has been studied for years. Much work was done at the Forest Products Laboratory in the last 15 years on the fundamental process of both short-and long-term exposure to heat on wood materials and its interaction with various treatment chemicals. This work...

Effects of wet mat curing time and earlier loading on long-term durability of bridge decks : compressive strength, maturity and strength durability index (SDI).

DOT National Transportation Integrated Search

2009-01-01

There is increasing pressure from owners, contractors, and the public to open bridge decks sooner to full : traffic loads. As a result, a set of criteria or guidelines is needed to determine when concrete bridge decks can : safely be opened. Today, c...

Durability of aircraft composite materials

NASA Technical Reports Server (NTRS)

Dextern, H. B.

1982-01-01

Confidence in the long term durability of advanced composites is developed through a series of flight service programs. Service experience is obtained by installing secondary and primary composite components on commercial and military transport aircraft and helicopters. Included are spoilers, rudders, elevators, ailerons, fairings and wing boxes on transport aircraft and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on helicopters. Materials included in the evaluation are boron/epoxy, Kevlar/epoxy, graphite/epoxy and boron/aluminum. Inspection, maintenance, and repair results for the components in service are reported. The effects of long term exposure to laboratory, flight, and outdoor environmental conditions are reported for various composite materials. Included are effects of moisture absorption, ultraviolet radiation, and aircraft fuels and fluids.

Concrete performance using low-degradation aggregates.

DOT National Transportation Integrated Search

2012-06-01

The durability of Portland cement concrete (PCC) has long been identified as a concern by transportation communities around the United States. In this study, the long-term performance of two batches of concrete incorporating either low-degradation (L...

Fluctuations of Lightning Casualties in the United States: 1959-1990.

NASA Astrophysics Data System (ADS)

López, Raúl E.; Holle, Ronald L.

1996-03-01

Long-term fluctuations in the number of lightning deaths and injuries from 1959 to 1990 have been examined for the contiguous United States. After taking into account the population increase, there was an overall trend amounting to a 30% reduction in casualties during the period. It is possible that this trend resulted from improved forecasts and warnings, increased education efforts of the public, and socioeconomic changes.In addition, there was a 40% reduction in the number of deaths but not of nonfatal injuries. This additional reduction in deaths was probably due to improved medical attention given to lightning victims and a wider knowledge of cardiopulmonary resuscitation techniques among the public. Improved medical care would increase the chances of a person surviving a lightning strike but would not affect the total number of casualties.Superimposed on the overall downward trend there were fluctuations of one or two decades in duration. From 1959 until 1968 there was a sharp reduction in the number of casualties, but starting in 1969 and continuing until the present, there was an overall increase. These oscillations appear to be climatologically related. The patterns of these fluctuations were parallel to nationwide changes in thunder-day frequencies, cyclone frequencies, and surface temperature values, representing thunderstorm, synoptic, and continental scales.

Monitoring the performance of timber bridges over the long term

Treesearch

James P. Wacker; Marc R. Joyal; Joseph F. Murphy; Xiping Wang

2007-01-01

Timber bridges are often viewed by engineers as less durable than steel or concrete structures. However, they remain a durable and economical option along secondary roads in many rural areas of the country. With well over 75,000 bridges listed by the Federal Highway Administration’s National Bridge Inventory as having timber superstructures as of 2002, they represent...

Ten-year performance of treated northeastern softwoods in aboveground and ground-contact exposures

Treesearch

Douglas M. Crawford; Rodney C. De Groot; Lee R. Gjovik

The commercial value of several softwood species of the northeastern United States could be increased if these woods could be treated to meet existing American Wood Preserversa Association (AWPA) Standards and used in durable structures. We evaluated the long-term durability of incised and unincised white pine, red pine, eastern spruce, balsam fir, and eastern hemlock...

Five-year field trials using preservative-treated, second-growth Douglas-fir exposed in ground contact in Australia

Treesearch

Rodney C. De Groot; Douglas M. Crawford; Jack Norton; John Keith

2000-01-01

The durability of preservative-treated stakes of second-growth Coastal Douglas-fir was evaluated in a field plot in northern Queensland, Australia. Results from this field trial indicate that second-growth Douglas-fir can be treated with preservatives to meet Australian standards and will provide long-term durability in adverse environments. Data presented indicate...

Long term durability of solid heartwood stakes treated with ACA or CCA

Treesearch

Mark E. Mankowski; Stan Lebow; Grant Kirker; Lee Gjovik

2017-01-01

Limited long-term field data exist evaluating the benefit of chemical wood preservatives on refractory wood species with abundant heartwood. The objective of this study was to determine the effectiveness of preservative-treated refractory solid heartwood comprised of southern pine, Douglas-fir, or Engelmann spruce. Non-incised and incised solid lumber of these species...

Long-term follow-up of aneurysms treated electively with woven stent-assisted coiling.

PubMed

Cheung, Nicholas K; Chiu, Albert Hy; Cheung, Andrew K; Wenderoth, Jason D

2017-12-15

Preliminary short-term results for stent-assisted coil embolization (SACE) using woven/braided stents have been promising. However, evidence supporting mid- to long-term efficacy and durability is lacking. To report the long-term results for the durability of elective intracranial aneurysms treated with woven stents. Between May 2012 and May 2015, 98 consecutive patients with 103 aneurysms underwent elective woven SACE across three Australian neurovascular centres. All patients had immediate, 6- and 18-month clinical and radiological follow-up. Radiological assessment was performed with modified Raymond-Roy occlusion scores based on angiography results, while clinical assessment was based on the modified Rankin Scale. Six-month follow-up was available in 100 aneurysms, and an 18-month follow-up in 97 aneurysms. Total occlusion rates of 82% were achieved at inception, 82% at 6 months, and 90% at 18 months. Satisfactory occlusion with small neck remnants was present in 17% at inception, 16% at 6 months, and 9% at 18 months. Good neurological outcomes were achieved in 95% at 18 months. Intraprocedural thromboembolic events were recorded in 3% and delayed events in 1% (all in patients taking clopidogrel). Aneurysm recurrence occurred in one patient (1%). Technical complications occurred in 5%. The total complication rate was 10%. Woven SACE is safe, efficacious, and durable at long-term 18-month follow-up, with very low recurrence and re-treatment rates. Preliminary results appear better than those for traditional laser-cut stents. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Comparison of laparoscopic jejunostomy tube to percutaneous endoscopic gastrostomy tube with jejunal extension: long-term durability and nutritional outcomes.

PubMed

Haskins, Ivy N; Strong, Andrew T; Baginsky, Mary; Sharma, Gautam; Karafa, Matthew; Ponsky, Jeffrey L; Rodriguez, John H; Kroh, Matthew D

2018-05-01

Enteral access through the jejunum is indicated when patients cannot tolerate oral intake or gastric feeding. While multiple approaches for feeding jejunal access exist, few studies have compared the efficacy of these techniques. The purpose of this study was to investigate the long-term durability, re-intervention rates, and nutritional outcomes following percutaneous endoscopic gastrostomy tubes with jejunal extension tubes (PEG-JET) versus laparoscopic jejunostomy tubes (j-tubes). Retrospective chart review was performed on all patients who underwent PEG-JET or laparoscopic jejunostomy tube placement from January 2005 through December 2015 at our institution. Thirty-day and long-term outcomes were compared between the two groups. A total of 105 patients underwent PEG-JET and 307 patients underwent laparoscopic j-tube placement during the defined study period. In terms of 30-day outcomes, patients who underwent PEG-JET placement were significantly more likely to experience a tube dislodgement event (p = 0.005) and undergo a re-intervention (p < 0.001). Patients who had a laparoscopic j-tube placed were significantly more likely to meet their enteral feeding goals (p = 0.002) and less likely to require nutritional supplementation with total parenteral nutrition (TPN) (p < 0.001). With regard to long-term outcomes, patients who underwent PEG-JET placement were significantly more likely to experience tube occlusion (p < 0.001) and require an endoscopic or surgical tube re-intervention (p < 0.001). Patients who underwent laparoscopic j-tube placement were significantly more likely to experience a tube site leak (p = 0.015) but were less likely to require nutritional supplementation with TPN (p = 0.001). Laparoscopic jejunostomy tubes provide more durable long-term enteral access compared to PEG-JET. Consideration should be given to laparoscopic jejunostomy tube placement in eligible patients who cannot tolerate oral intake or gastric enteral feeding.

Long-Term Durability Test for the Left Ventricular Assist System EVAHEART under the Physiologic Pulsatile Load.

PubMed

Kitano, Tomoya; Iwasaki, Kiyotaka

The EVAHEART Left Ventricular Assist System (LVAS) was designed for the long-term support of a patient with severe heart failure. It has an original water lubrication system for seal and bearing and wear on these parts was considered one of its critical failure modes. A durability test focusing on wear was designed herein. We developed a mock loop, which generates a physiologic pulsatile flow and is sufficiently durable for a long-term test. The pulsatile load and the low fluid viscosity enable the creation of a severe condition for the mechanical seal. A total of 18 EVAHEART blood pumps completed 2 years of operation under the pulsatile condition without any failure. It indicated the EVAHEART blood pump had a greater than 90% reliability with a 88% confidence level. The test was continued with six blood pumps and achieved an average of 8.6 years, which was longer than the longest clinical use in Japan. The test result showed that no catastrophic, critical, marginal, or minor failures of the blood pump or their symptoms were observed. The seal performance was maintained after the test. Moreover, the surface roughness did not change, which showed any burn or abnormal wear occurred. The original water lubrication system equipped in EVAHEART LVAS prevent severe wear on the seal and the bearing, and it can be used in the bridge to transplant and destination therapy.

Predicting the long-term durability of hemp-lime renders in inland and coastal areas using Mediterranean, Tropical and Semi-arid climatic simulations.

PubMed

Arizzi, Anna; Viles, Heather; Martín-Sanchez, Inés; Cultrone, Giuseppe

2016-01-15

Hemp-based composites are eco-friendly building materials as they improve energy efficiency in buildings and entail low waste production and pollutant emissions during their manufacturing process. Nevertheless, the organic nature of hemp enhances the bio-receptivity of the material, with likely negative consequences for its long-term performance in the building. The main purpose of this study was to study the response at macro- and micro-scale of hemp-lime renders subjected to weathering simulations in an environmental cabinet (one year was condensed in twelve days), so as to predict their long-term durability in coastal and inland areas with Mediterranean, Tropical and Semi-arid climates, also in relation with the lime type used. The simulated climatic conditions caused almost unnoticeable mass, volume and colour changes in hemp-lime renders. No efflorescence or physical breakdown was detected in samples subjected to NaCl, because the salt mainly precipitates on the surface of samples and is washed away by the rain. Although there was no visible microbial colonisation, alkaliphilic fungi (mainly Penicillium and Aspergillus) and bacteria (mainly Bacillus and Micrococcus) were isolated in all samples. Microbial growth and diversification were higher under Tropical climate, due to heavier rainfall. The influence of the bacterial activity on the hardening of samples has also been discussed here and related with the formation and stabilisation of vaterite in hemp-lime mixes. This study has demonstrated that hemp-lime renders show good durability towards a wide range of environmental conditions and factors. However, it might be useful to take some specific preventive and maintenance measures to reduce the bio-receptivity of this material, thus ensuring a longer durability on site. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly durable, coking and sulfur tolerant, fuel-flexible protonic ceramic fuel cells.

PubMed

Duan, Chuancheng; Kee, Robert J; Zhu, Huayang; Karakaya, Canan; Chen, Yachao; Ricote, Sandrine; Jarry, Angelique; Crumlin, Ethan J; Hook, David; Braun, Robert; Sullivan, Neal P; O'Hayre, Ryan

2018-05-01

Protonic ceramic fuel cells, like their higher-temperature solid-oxide fuel cell counterparts, can directly use both hydrogen and hydrocarbon fuels to produce electricity at potentially more than 50 per cent efficiency 1,2 . Most previous direct-hydrocarbon fuel cell research has focused on solid-oxide fuel cells based on oxygen-ion-conducting electrolytes, but carbon deposition (coking) and sulfur poisoning typically occur when such fuel cells are directly operated on hydrocarbon- and/or sulfur-containing fuels, resulting in severe performance degradation over time 3-6 . Despite studies suggesting good performance and anti-coking resistance in hydrocarbon-fuelled protonic ceramic fuel cells 2,7,8 , there have been no systematic studies of long-term durability. Here we present results from long-term testing of protonic ceramic fuel cells using a total of 11 different fuels (hydrogen, methane, domestic natural gas (with and without hydrogen sulfide), propane, n-butane, i-butane, iso-octane, methanol, ethanol and ammonia) at temperatures between 500 and 600 degrees Celsius. Several cells have been tested for over 6,000 hours, and we demonstrate excellent performance and exceptional durability (less than 1.5 per cent degradation per 1,000 hours in most cases) across all fuels without any modifications in the cell composition or architecture. Large fluctuations in temperature are tolerated, and coking is not observed even after thousands of hours of continuous operation. Finally, sulfur, a notorious poison for both low-temperature and high-temperature fuel cells, does not seem to affect the performance of protonic ceramic fuel cells when supplied at levels consistent with commercial fuels. The fuel flexibility and long-term durability demonstrated by the protonic ceramic fuel cell devices highlight the promise of this technology and its potential for commercial application.

Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grin, A.; Lstiburek, J.

This guide provides information and recommendations to the following groups: insulation contractors; general contractors; builders; home remodelers; mechanical contractors; and homeowners, as a guide to the work that needs to be done. The order of work completed during home construction and retrofit improvements is important. Health and safety issues must be addressed first and are more important than durability issues. And durability issues are more important than saving energy. Not all techniques can apply to all houses. Special conditions will require special action. Some builders or homeowners will wish to do more than the important but basic retrofit strategies outlinedmore » by this guide. The following are best practice and product recommendations from the interviewed contractors and homebuilders who collectively have a vast amount of experience. Three significant items were discussed with the group which are required to make taped insulating sheathing a simple, long term, and durable drainage plane: 1. Horizontal joints should be limited or eliminated wherever possible; 2. Where a horizontal joint exists use superior materials; 3. Frequent installation inspection and regular trade training are required to maintain proper installation. Section 5 of this measure guideline contains the detailed construction procedure for the three recommended methods to effectively seal the joints in exterior insulating sheathing to create a simple, long term, and durable drainage plane.« less

[GERD: endoscopic antireflux therapies].

PubMed

Caca, K

2006-08-02

A couple of minimally-invasive, endoscopic antireflux procedures have been developed during the last years. Beside endoscopic suturing these included injection/implantation technique of biopolymers and application of radiofrequency. Radiofrequency (Stretta) has proved only a very modest effect, while implantation techniques have been abandoned due to lack of long-term efficacy (Gatekeeper) or serious side effects (Enteryx). While first generation endoluminal suturing techniques (EndoCinch, ESD) demonstrated a proof of principle their lack of durability, due to suture loss, led to the development of a potentially durable transmural plication technique (Plicator). In a prospective-randomized, sham-controlled trial the Plicator procedure proved superiority concerning reflux symptoms, medication use and esophageal acid exposure (24-h-pH-metry). While long-term data have to be awaited to draw final conclusions, technical improvements will drive innovation in this field.

Building a durable response to HIV/AIDS: implications for health systems.

PubMed

Atun, Rifat; Bataringaya, Jacqueline

2011-08-01

The remarkable rise in investments for HIV control programs in 2003-2010 enabled an unprecedented expansion of access to HIV services in low-income and middle-income countries. By the end of 2010, more than 5.2 million people were receiving antiretroviral therapy (ART), which transformed HIV infection, once a death sentence, into a long-term illness. The rapid expansion in the number of persons receiving ART means that health systems must continue to provide acute life-saving care for those with advanced HIV/AIDS although also providing chronic care services to expanding cohorts of more stable patients who are doing well on ART. This expansion also means a transition from an emergency response to the epidemic, characterized by a public health approach, to a more integrated and durable approach to HIV prevention, care, and treatment services that fosters individualized care for those requiring long-term antiretroviral treatment. Yet most low-income and middle-income countries, which have weak health systems, are poorly prepared to make this transition. In this article, we highlight the challenges health systems face in developing a sustained and durable response to HIV/AIDS. The article analyses the readiness of health systems to combine rapid expansion of ART access with long-term treatment and continuity of care for a growing cohort of patients. We argue that effective management of a transition from an emergency AIDS response to long-term programatic strategies will require a paradigm shift that enables leveraging investments in HIV to build sustainable health systems for managing large cohorts of patients receiving ART although meeting the immediate needs of those who remain without access to HIV treatment and care.

Contributions to DoD Mission Success from High Performance Computing - March 1995

DTIC Science & Technology

1995-03-01

the flow . The physics to be considered may entail additional force fields, coupling to surface physics and microphysics, changes of phase, changes...in this program concerns the structural mechanics of bolted-on propeller blades. An important objective of the program was to determine the effects of...motion between the rotor blades and the airframe. The flow past each component is then computed using an efficient, implicit three-dimensional unsteady

Modeling the long-term durability of concrete barriers in the context of low-activity waste storage

NASA Astrophysics Data System (ADS)

Protière, Y.; Samson, E.; Henocq, P.

2013-07-01

The paper investigates the long-term durability of concrete barriers in contact with a cementitious wasteform designed to immobilize low-activity nuclear waste. The high-pH pore solution of the wasteform contains high concentration level of sulfate, nitrate, nitrite and alkalis. The multilayer concrete/wasteform system was modeled using a multiionic reactive transport model accounting for coupling between species, dissolution/ precipitation reactions, and feedback effect. One of the primary objectives was to investigate the risk associated with the presence of sulfate in the wasteform on the durability of concrete. Simulation results showed that formation of expansive phases, such as gypsum and ettringite, into the concrete barrier was not extensive. Based on those results, it was not possible to conclude that concrete would be severely damaged, even after 5,000 years. Lab work was performed to provide data to validate the modeling results. Paste samples were immersed in sulfate contact solutions and analyzed to measure the impact of the aggressive environment on the material. The results obtained so far tend to confirm the numerical simulations.

Verification of Accelerated Testing Methodology for Long-Term Durability of CFRP Laminates for Marine Use

DTIC Science & Technology

2012-01-30

CFRP LAMINATES FOR MARINE USE Sa. CONTRACT NUMBER 5b. GRANT NUMBER N00014-06-1-1139 Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Miyano, Yasushi...prediction of CFRP laminates proposed and confirmed experimentally in the previous ONR project of Grant # N000140110949 was verified theoretically and refined...DURABILITY OF CFRP LAMINATES FOR MARINE USE Principal Investigator Yasushi Miyano Co-principal Investigator Isao Kimpara Materials System

NDT evaluation of long-term bond durability of CFRP-structural systems applied to RC highway bridges

NASA Astrophysics Data System (ADS)

Crawford, Kenneth C.

2016-06-01

The long-term durability of CFRP structural systems applied to reinforced-concrete (RC) highway bridges is a function of the system bond behavior over time. The sustained structural load performance of strengthened bridges depends on the carbon fiber-reinforced polymer (CFRP) laminates remaining 100 % bonded to concrete bridge members. Periodic testing of the CFRP-concrete bond condition is necessary to sustain load performance. The objective of this paper is to present a non-destructive testing (NDT) method designed to evaluate the bond condition and long-term durability of CFRP laminate (plate) systems applied to RC highway bridges. Using the impact-echo principle, a mobile mechanical device using light impact hammers moving along the length of a bonded CFRP plate produces unique acoustic frequencies which are a function of existing CFRP plate-concrete bond conditions. The purpose of this method is to test and locate CFRP plates de-bonded from bridge structural members to identify associated deterioration in bridge load performance. Laboratory tests of this NDT device on a CFRP plate bonded to concrete with staged voids (de-laminations) produced different frequencies for bonded and de-bonded areas of the plate. The spectra (bands) of frequencies obtained in these tests show a correlation to the CFRP-concrete bond condition and identify bonded and de-bonded areas of the plate. The results of these tests indicate that this NDT impact machine, with design improvements, can potentially provide bridge engineers a means to rapidly evaluate long lengths of CFRP laminates applied to multiple highway bridges within a national transportation infrastructure.

Learnable Interfaces--Leveraging Navigation by Design

ERIC Educational Resources Information Center

Swanson, Kari Gunvaldson

2012-01-01

Complex productivity applications that integrate tasks in the workplace are becoming more common. Usability typically focuses on short-term, immediate measures of task performance. This study incorporates a long-term goal of more durable learning, focusing on implicit learning (spontaneous, unplanned, usually unconscious learning as a result of…

Ensuring Longevity: Ancient Glasses Help Predict Durability of Vitrified Nuclear Waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weaver, Jamie L.; McCloy, John S.; Ryan, Joseph V.

How does glass alter with time? For the last hundred years this has been an important question to the fields of object conservation and archeology to ensure the preservation of glass artifacts. This same question is part of the development and assessment of durable glass waste forms for the immobilization of nuclear wastes. Researchers have developed experiments ranging from simple to highly sophisticated to answer this question, and, as a result, have gained significant insight into the mechanisms that drive glass alteration. However, the gathered data have been predominately applicable to only short-term alteration times, i.e. over the course ofmore » decades. What has remained elusive is the long-term mechanisms of glass alteration[1]. These mechanisms are of particular interest to the international nuclear waste glass community as they strive to ensure that vitrified products will be durable for thousands to tens of thousands of years. For the last thirty years this community has been working to fill this research gap by partnering with archeologists, museum curators, and geologists to identify hundred to million-year old glass analogues that have altered in environments representative of those expected at potential nuclear waste disposal sites. The process of identifying a waste glass relevant analogue is challenging as it requires scientists to relate data collected from short-term laboratory experiments to observations made from long-term analogues and extensive geochemical modeling.« less

Durability, value, and reliability of selected electric powered wheelchairs.

PubMed

Fass, Megan V; Cooper, Rory A; Fitzgerald, Shirley G; Schmeler, Mark; Boninger, Michael L; Algood, S David; Ammer, William A; Rentschler, Andrew J; Duncan, John

2004-05-01

To compare the durability, value, and reliability of selected electric powered wheelchairs (EPWs), purchased in 1998. Engineering standards tests of quality and performance. A rehabilitation engineering center. Fifteen EPWs: 3 each of the Jazzy, Quickie, Lancer, Arrow, and Chairman models. Not applicable. Wheelchairs were evaluated for durability (lifespan), value (durability, cost), and reliability (rate of repairs) using 2-drum and curb-drop machines in accordance with the standards of the American National Standards Institute and Rehabilitation Engineering and Assistive Technology Society of North America. The 5 brands differed significantly (P

A rule-based expert system applied to moisture durability of building envelopes

DOE PAGES

Boudreaux, Philip R.; Pallin, Simon B.; Accawi, Gina K.; ...

2018-01-09

The moisture durability of an envelope component such as a wall or roof is difficult to predict. Moisture durability depends on all the construction materials used, as well as the climate, orientation, air tightness, and indoor conditions. Modern building codes require more insulation and tighter construction but provide little guidance about how to ensure these energy-efficient assemblies remain moisture durable. Furthermore, as new products and materials are introduced, builders are increasingly uncertain about the long-term durability of their building envelope designs. Oak Ridge National Laboratory and the US Department of Energy’s Building America Program are applying a rule-based expert systemmore » methodology in a web tool to help designers determine whether a given wall design is likely to be moisture durable and provide expert guidance on moisture risk management specific to a wall design and climate. Finally, the expert system is populated with knowledge from both expert judgment and probabilistic hygrothermal simulation results.« less

A rule-based expert system applied to moisture durability of building envelopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boudreaux, Philip R.; Pallin, Simon B.; Accawi, Gina K.

The moisture durability of an envelope component such as a wall or roof is difficult to predict. Moisture durability depends on all the construction materials used, as well as the climate, orientation, air tightness, and indoor conditions. Modern building codes require more insulation and tighter construction but provide little guidance about how to ensure these energy-efficient assemblies remain moisture durable. Furthermore, as new products and materials are introduced, builders are increasingly uncertain about the long-term durability of their building envelope designs. Oak Ridge National Laboratory and the US Department of Energy’s Building America Program are applying a rule-based expert systemmore » methodology in a web tool to help designers determine whether a given wall design is likely to be moisture durable and provide expert guidance on moisture risk management specific to a wall design and climate. Finally, the expert system is populated with knowledge from both expert judgment and probabilistic hygrothermal simulation results.« less

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. Copyright © 2015 Elsevier B.V. All rights reserved.

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. (c) 2009 Wiley Periodicals, Inc.

Short-term mechanical circulatory support as a bridge to durable left ventricular assist device implantation in refractory cardiogenic shock: a systematic review and meta-analysis.

PubMed

den Uil, Corstiaan A; Akin, Sakir; Jewbali, Lucia S; Dos Reis Miranda, Dinis; Brugts, Jasper J; Constantinescu, Alina A; Kappetein, Arie Pieter; Caliskan, Kadir

2017-07-01

Short-term mechanical circulatory support (MCS) is increasingly used as a bridge to decision in patients with refractory cardiogenic shock. Subsequently, these patients might be bridged to durable MCS either as a bridge to candidacy/transplantation, or as destination therapy. The aim of this study was to review support duration and clinical outcome of short-term MCS in cardiogenic shock, and to analyse application of this technology as a bridge to long-term cardiac support (left ventricular assist device, LVAD) from 2006 till June 2016. Using Cochrane Register of Trials, Embase and Medline, a systematic review was performed on patients with cardiogenic shock from acute myocardial infarction, end-stage cardiomyopathy, or acute myocarditis, receiving short-term MCS. Studies on periprocedural, post-cardiotomy and cardiopulmonary resuscitation support were excluded. Thirty-nine studies, mainly registries of heterogeneous patient populations (n = 4151 patients), were identified. Depending on the device used (intra-aortic balloon pump, TandemHeart, Impella 2.5, Impella 5.0, CentriMag and peripheral veno-arterial extracorporeal membrane oxygenation), mean support duration was (range) 1.6-25 days and the mean proportion of short-term MCS patients discharged was (range) 45-66%. The mean proportion of bridge to durable LVAD was (range) 3-30%. Bridge to durable LVAD was most frequently performed in patients with end-stage cardiomyopathy (22 [12-35]%). We conclude that temporary MCS can be used to bridge patients with cardiogenic shock towards durable LVAD. Clinicians are encouraged to share their results in a large multicentre registry in order to investigate optimal device selection and best duration of support. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Building America Case Study: Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This guide provides information and recommendations to the following groups: Insulation contractors, General contractors, Builders, Home remodelers, Mechanical contractors, and Homeowners as a guide to the work that needs to be done. The order of work completed during home construction and retrofit improvements is important. Health and safety issues must be addressed first and are more important than durability issues. And durability issues are more important than saving energy. Not all techniques can apply to all houses. Special conditions will require special action. Some builders or homeowners will wish to do more than the important but basic retrofit strategies outlinedmore » by this guide. The following are best practice and product recommendations from the interviewed contractors and home builders who collectively have a vast amount of experience. Three significant items were discussed with the group which are required to make taped insulating sheathing a simple, long term, and durable drainage plane: 4. Horizontal joints should be limited or eliminated wherever possible 5. Where a horizontal joint exists use superior materials 6. Frequent installation inspection and regular trade training are required to maintain proper installation Section 5 of this measure guideline contains the detailed construction procedure for the three recommended methods to effectively seal the joints in exterior insulating sheathing to create a simple, long term, and durable drainage plane.« less

The Development of 2700-3000 F Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2015-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned 2700-3000F EBC - CMC systems to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current NASA candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, cyclic durability, erosion-impact resistance, and long-term system performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

Bare metal stents, durable polymer drug eluting stents, and biodegradable polymer drug eluting stents for coronary artery disease: mixed treatment comparison meta-analysis

PubMed Central

Toklu, Bora; Amoroso, Nicholas; Fusaro, Mario; Kumar, Sunil; Hannan, Edward L; Faxon, David P; Feit, Frederick

2013-01-01

Objective To compare the efficacy and safety of biodegradable polymer drug eluting stents with those of bare metal stents and durable polymer drug eluting stents. Design Mixed treatment comparison meta-analysis of 258 544 patient years of follow-up from randomized trials. Data sources and study selection PubMed, Embase, and Central were searched for randomized trials comparing any of the Food and Drug Administration approved durable polymer drug eluting stents (sirolimus eluting, paclitaxel eluting, cobalt chromium everolimus eluting, platinum chromium everolimus eluting, zotarolimus eluting-Endeavor, and zotarolimus eluting-Resolute) or biodegradable polymer drug eluting stents, with each other or against bare metal stents. Outcomes Long term efficacy (target vessel revascularization, target lesion revascularization) and safety (death, myocardial infarction, stent thrombosis). Landmark analysis at more than one year was evaluated to assess the potential late benefit of biodegradable polymer drug eluting stents. Results From 126 randomized trials and 258 544 patient years of follow-up, for long term efficacy (target vessel revascularization), biodegradable polymer drug eluting stents were superior to paclitaxel eluting stents (rate ratio 0.66, 95% credibility interval 0.57 to 0.78) and zotarolimus eluting stent-Endeavor (0.69, 0.56 to 0.84) but not to newer generation durable polymer drug eluting stents (for example: 1.03, 0.89 to 1.21 versus cobalt chromium everolimus eluting stents). Similarly, biodegradable polymer drug eluting stents were superior to paclitaxel eluting stents (rate ratio 0.61, 0.37 to 0.89) but inferior to cobalt chromium everolimus eluting stents (2.04, 1.27 to 3.35) for long term safety (definite stent thrombosis). In the landmark analysis after one year, biodegradable polymer drug eluting stents were superior to sirolimus eluting stents for definite stent thrombosis (rate ratio 0.29, 0.10 to 0.82) but were associated with increased mortality compared with cobalt chromium everolimus eluting stents (1.52, 1.02 to 2.22). Overall, among all stent types, the newer generation durable polymer drug eluting stents (zotarolimus eluting stent-Resolute, cobalt chromium everolimus eluting stents, and platinum chromium everolimus eluting stents) were the most efficacious (lowest target vessel revascularization rate) stents, and cobalt chromium everolimus eluting stents were the safest with significant reductions in definite stent thrombosis (rate ratio 0.35, 0.21 to 0.53), myocardial infarction (0.65, 0.55 to 0.75), and death (0.72, 0.58 to 0.90) compared with bare metal stents. Conclusions Biodegradable polymer drug eluting stents are superior to first generation durable polymer drug eluting stents but not to newer generation durable polymer stents in reducing target vessel revascularization. Newer generation durable polymer stents, and especially cobalt chromium everolimus eluting stents, have the best combination of efficacy and safety. The utility of biodegradable polymer stents in the context of excellent clinical outcomes with newer generation durable polymer stents needs to be proven. PMID:24212107

Long-term durability of CCA and ACA : how is 0.4 doing?

Treesearch

Stan T. Lebow; Cherilyn A. Hatfield; Bessie Woodward

2010-01-01

For decades the phrase “point 4” was synonymous with wood treated for use in contact with the ground. In this paper we review how and why the 0.4 lb/ft3 (6.4 kg/m3) retention became such an accepted standard, and then evaluate how well this retention has performed in long term stake testing. Data from plots near Saucier,...

Long-Term benefits of stabilizing soil subgrades.

DOT National Transportation Integrated Search

2002-06-01

The main intent of this study was an attempt to address questions concerning bearing strengths, longevity, durability, structural credit, economics, and performance of pavements resting on soil subgrades mixed with chemical admixtures. In-depth field...

CONTECH(R) A-2000 polyvinyl chloride (PVC) plastic pipe.

DOT National Transportation Integrated Search

2015-03-01

Determine the effectiveness and long-term durability of the Contech A-2000 PVC pipe : in an irrigation application. This type of pipe may prove to be a viable alternative to : reinforced concrete pipe (RCP).

Diffusion vs. concentration of chloride ions in concrete.

DOT National Transportation Integrated Search

2014-06-01

This investigation was performed to gain insight and assist in determining the long-term durability of : reinforced concrete structures where the external chloride concentrations are different than those typically : observed at the permanently immers...

Long-term Outcomes of Bariatric Surgery: A National Institutes of Health Symposium

PubMed Central

Courcoulas, Anita P.; Yanovski, Susan Z.; Bonds, Denise; Eggerman, Thomas L.; Horlick, Mary; Staten, Myrlene A.; Arterburn, David E.

2017-01-01

Importance The clinical evidence base demonstrating bariatric surgery’s health benefits is much larger than it was when the NIH last held a Consensus Panel in 1991. Still, it remains unclear whether ongoing studies will address critical questions about long-term complication rates and the sustainability of weight loss and comorbidity control. Objective The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Heart, Lung, and Blood Institute (NHLBI) convened a multidisciplinary workshop in May 2013 to summarize the current state of knowledge of bariatric surgery, review research findings on the long-term outcomes of bariatric surgery, and establish priorities for future research directions. Evidence Review The evidence presented at the workshop was selected by the planning committee for both its quality and duration of follow up. The data review emphasized RCTs and large observational studies with long-term follow up, with or without a control group. Findings Several small RCTs showed greater weight loss and T2DM remission compared to non-surgical treatments within the first 2 years of follow-up after bariatric surgery. Large, long-term observational studies show durable (>5 years) weight loss, diabetes and lipid improvements with bariatric surgery. Still unclear are predictors of outcomes, long-term complications, long-term survival, micro- and macro-vascular events, mental health outcomes, and costs. The studies needed to address these knowledge gaps would be expensive and logistically difficult to perform. Conclusions and Relevance High-quality evidence shows that bariatric surgical procedures result in greater weight loss than non-surgical treatments and are more effective at inducing initial T2DM remission in obese patients. More information is needed about the long term durability of comorbidity control and complications after bariatric procedures and this evidence will most likely come from carefully designed observational studies. PMID:25271405

Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

Economic Analysis for an F-22 Organic vs. Contractor Aircraft Battle Damage Repair Ownership Decision

DTIC Science & Technology

1997-09-01

cost . That is, a change in the cost driver will cause a change in the total cost of a related cost object. ( Horngren , et al., 1994) Cost Object...Anything for which a separate measurement of costs is desired. ( Horngren , et al., 1994) 48 Fixed Cost Cost that does not change in total despite changes...in a cost driver. ( Horngren , et al., 1994) Incremental Cost The difference in total cost between two alternatives. Also called

Long-term Hearing Preservation After Resection of Vestibular Schwannoma: A Systematic Review and Meta-analysis.

PubMed

Ahsan, Syed F; Huq, Farhan; Seidman, Michael; Taylor, Andrew

2017-12-01

The objective is to perform a systematic review and meta-analysis of the literature on the long-term results of hearing preservation after vestibular schwannoma resection. Ovid/Medline, PubMed, Embase, and the Cochrane library from January 1980 to January 2015. Inclusion criteria: age ≥18 years, minimum 10 patients in the treatment group, hearing preserving microsurgery, no previous radiation treatment, serviceable hearing at immediate postop follow-up, hearing outcomes reported using Gardner Robinson or the American Academy of Otolaryngology-Head and Neck Surgeons hearing grading scales, and average follow-up of 5 years. Preoperative, immediate postoperative, and last follow-up audiograms were required. Exclusion criteria included neurofibromatosis type 2 patients and surgery for salvage therapy or decompression. Quality evaluated using Methodological Index for Non-Randomized Studies. Meta-analysis was performed using R v3.2.2, Metafor package v 1.9-7. Cohen's D was used to determine effect size. Ten reports had at least 5-year follow-up and used standardized hearing grading scales. The systematic review found that if hearing was preserved at Class A or B at early postop visit, the chance of preserving hearing at 5 years was excellent. Those who maintained speech discrimination score ≥ 89% at the early postoperative follow-up had better long-term hearing preservation. The meta-analysis reveals that only preoperative and postoperative pure-tone average was associated with long-term hearing preservation. Long-term (>5 yr) hearing durability rates are generally very good. Most studies do not report patient and tumor characteristics, therefore precluding combining studies for meta-analysis. Only preoperative and postoperative postoperative pure-tone average was associated with long-term hearing durability.

Simultaneous structural and environmental loading of an ultra-high performance concrete component

DOT National Transportation Integrated Search

2010-07-01

Ultra-high performance concrete (UHPC) is an advanced cementitious composite material which tends to exhibit superior properties such as increased durability, strength, and long-term stability. This experimental investigation focused on the flexural ...

Assessment of the long-term durability of concrete in radioactive waste repositories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, A.; Goult, D.J.; Hearne, J.A.

1986-01-01

A preliminary assessment of the long-term durability of concrete in a repository sited in clay is presented. The assessment is based on recorded experience of concrete structures and both field and laboratory studies. It is also supported by results of the examination of a concrete sample which had been buried in clay for 43 years. The engineering lifetime of a 1 m thick reinforced concrete slab, with one face in contact with clay, and the way in which pH in the repository as a whole is likely to vary with time have both been estimated from available data. The estimatesmore » indicate that engineering lifetimes of about 10/sup 3/ years are expected (providing that sulfate resisting cement is used) and that pH is likely to remain above 10.5 for about 10/sup 6/ years.« less

Effects of commercial aircraft operating environment on composite materials

NASA Technical Reports Server (NTRS)

Chapman, A. J.; Hoffman, D. J.; Hodges, W. T.

1980-01-01

Long term effects of commercial aircraft operating environment on the properties and durability of composite materials are being systematically explored. Composite specimens configured for various mechanical property tests are exposed to environmental conditions on aircraft in scheduled airline service, on racks at major airports, and to controlled environmental conditions in the laboratory. Results of tests following these exposures will identify critical parameters affecting composite durability, and correlation of the data will aid in developing methods for predicting durability. Interim results of these studies show that mass change of composite specimens on commercial aircraft depends upon the regional climate and season, and that mass loss from composite surfaces due to ultraviolet radiation can be largely prevented by aircraft paint.

Well-defined porous membranes for robust omniphobic surfaces via microfluidic emulsion templating

NASA Astrophysics Data System (ADS)

Zhu, Pingan; Kong, Tiantian; Tang, Xin; Wang, Liqiu

2017-06-01

Durability is a long-standing challenge in designing liquid-repellent surfaces. A high-performance omniphobic surface must robustly repel liquids, while maintaining mechanical/chemical stability. However, liquid repellency and mechanical durability are generally mutually exclusive properties for many omniphobic surfaces--improving one performance inevitably results in decreased performance in another. Here we report well-defined porous membranes for durable omniphobic surfaces inspired by the springtail cuticle. The omniphobicity is shown via an amphiphilic material micro-textured with re-entrant surface morphology; the mechanical durability arises from the interconnected microstructures. The innovative fabrication method--termed microfluidic emulsion templating--is facile, cost-effective, scalable and can precisely engineer the structural topographies. The robust omniphobic surface is expected to open up new avenues for diverse applications due to its mechanical and chemical robustness, transparency, reversible Cassie-Wenzel transition, transferability, flexibility and stretchability.

Current use of the artificial urinary sphincter and its long-term durability: a nationwide survey in Japan.

PubMed

Arai, Yoichi; Takei, Mineo; Nonomura, Katsuya; Baba, Shiro; Habuchi, Tomonori; Matsuda, Tadashi; Takahashi, Satoru; Igawa, Mikio; Kaiho, Yasuhiro; Nakagawa, Haruo

2009-01-01

Although the artificial urinary sphincter (AUS) is one of the most effective surgical treatments for severe urinary incontinence, little is known about its use in Japan. A nationwide survey was done to determine contemporary trends in AUS use and its long-term durability. Data on AUS units sold in Japan were provided directly by Takai Hospital Supply Co., Ltd., Tokyo, Japan, and a survey form was sent to all 44 institutes where AUS implantation had been carried out. The survey included various demographic and preoperative variables, surgical variables, and postoperative outcomes. Between 1994 and 2007, a total of 100 AUS devices had been provided in Japan. Of the 44 institutes, 24 responded to the survey, and a total of 64 patients were enrolled in the study. Post-urological surgery incontinence accounted for 81.3% of the indications. During the mean follow-up of 50 months, mechanical failure occurred in four (6.2%), and the device was removed in 13 (20.3%) due to infection (14.0%), erosion (4.7%), or urination difficulty (1.5%). Of the 58 patients evaluated, 91.4% reported social continence. Five- and 10-year failure-free rates were 74.8% and 70.1%, respectively. On multivariate analysis, operative time was an independent predictor of treatment failure (P = 0.0334). Considering recent trends in prostate surgery, the AUS may be significantly underused in Japan. Although excellent long-term durability has been achieved, a learning effect appears to be evident. The Japanese urological community needs to provide appropriate patients with this treatment option.

Laboratory and field evaluation of concrete paving curing effectiveness.

DOT National Transportation Integrated Search

2009-12-01

Ensuring that sufficient water is available in hydrating concrete is of great importance to produce durable : concrete and achieve both short- and long-term performance of concrete pavement. Excessive early-age : evaporation from the surface of concr...

Development of a Family of Ultra-High Performance Concrete Pi-Girders

DOT National Transportation Integrated Search

2014-01-01

Ultra-high performance concrete (UHPC) is an advanced cementitious composite material, which tends to exhibit superior properties such as exceptional durability, increased strength, and long-term stability. (See references 1-4.) The use of existing s...

Latissimus dorsi myocutaneous reconstruction: a study of long-term outcomes in a district general hospital.

PubMed

Kallaway, C; Humphreys, A; Laurence, N; Sutton, R

2016-11-01

INTRODUCTION The aim of this study was to evaluate the long-term outcome and durability of both autologous and implant-assisted latissimus dorsi reconstruction in a district general hospital over a 10-year follow-up period. METHODS A prospective cohort study was carried out using a detailed database of all latissimus dorsi flap reconstructions performed by a single consultant surgeon between 2003 and 2013 at the Royal United Hospital, Bath. The long-term outcome following reconstruction was assessed by analysing all episodes of 'reconstruction-specific' operations required from 6 months after the initial surgery. RESULTS The study included 110 patients with latissimus dorsi flap reconstructions, 21 autologous and 95 implant-assisted. Radiotherapy was given to 27 patients with reconstructed flaps. Mean follow-up was 69 months. Further reconstruction-specific surgery was needed in 27 (23%) cases, with 5 of these being post-radiotherapy flaps. Implant-related surgery was the most common reason for further surgery. Complications of the implant itself made up 52% of these cases, chronic sepsis being the most common. The rate of symptomatic capsular contracture requiring further surgery was 4.2%. Of these, one of four patients had undergone radiotherapy. DISCUSSION In our institution, latissimus dorsi reconstruction is durable and safe over the long term, with limited need for further substantial intervention to maintain a good outcome from the initial reconstruction. Autologous flaps were less likely to require further surgery over the long term compared with implant-based reconstructions. The low rate of symptomatic capsular contracture may be due to the protective mechanism provided by the extended harvest flap used.

Long-term micro-Deval durability of andesite aggregate

NASA Astrophysics Data System (ADS)

Czinder, Balázs; Török, Ákos

2017-04-01

Micro-Deval tests have been intensively used for analysing aggregate durability. The tests procedure described in details in the European Norm (EN 1097-1:2011). The current research intends to evaluate the long term durability of andesite aggregate by using extended micro-Deval tests. Andesite aggregate from Recsk (Hungary) was used for the tests. The tested andesite is a massive porphyritic biotite amphibol andesite that was formed during Eocene volcanism and forms a part of Mátra Mountains volcanic complex in NE Hungary. The aggregates were crushed and screened. Size fractions of 10.0/14.0 mm representing minimum and maximum grain sizes were used in the tests. 500 g of aggregate specimens were loaded in the steel drum and 2500 ml of water was added besides the 5000 g of steel balls into the device. The steel balls have a diameter of 10 mm according to EN. The test material - in the first stage - was subjected to 12,000 revolutions in the drum. This number is suggested by the EN. The micro-Deval coefficient was calculated after this first stage. Further wear of the andesitic material was tested by using additional revolutions. The increase in revolutions of the drum was in 12,000 rotation steps, reached 48,000 revolutions as a maximum. The tests were aimed to model the wear of aggregate on a longer term. It was also used to assess the durability of the aggregate when it is applied in engineering structures. The micro-Deval test results suggest that additional revolutions caused additional loss in material, i.e. increase in micro-Deval coefficient. A correlation is suggested between the revolution and andesite wear.

Well-defined porous membranes for robust omniphobic surfaces via microfluidic emulsion templating

PubMed Central

Zhu, Pingan; Kong, Tiantian; Tang, Xin; Wang, Liqiu

2017-01-01

Durability is a long-standing challenge in designing liquid-repellent surfaces. A high-performance omniphobic surface must robustly repel liquids, while maintaining mechanical/chemical stability. However, liquid repellency and mechanical durability are generally mutually exclusive properties for many omniphobic surfaces—improving one performance inevitably results in decreased performance in another. Here we report well-defined porous membranes for durable omniphobic surfaces inspired by the springtail cuticle. The omniphobicity is shown via an amphiphilic material micro-textured with re-entrant surface morphology; the mechanical durability arises from the interconnected microstructures. The innovative fabrication method—termed microfluidic emulsion templating—is facile, cost-effective, scalable and can precisely engineer the structural topographies. The robust omniphobic surface is expected to open up new avenues for diverse applications due to its mechanical and chemical robustness, transparency, reversible Cassie–Wenzel transition, transferability, flexibility and stretchability. PMID:28604698

A Study on a Prognosis Algorithm for PEMFC Lifetime Prediction based on Durability Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xian; Pisu, Pierluigi; Toops, Todd J

2010-01-01

Of the fuel cells being studied, the proton exchange membrane fuel cell (PEMFC) is viewed as the most promising for transportation. Yet until today, the commercialization of the PEMFC has not been widespread in spite of its large expectation. Poor long term performances or durability, and high production and maintenance costs account for the main reasons. For the final commercialization of fuel cell in transportation field, the durability issue must be addressed, while the costs should be further brought down. In the meantime, health-monitoring and prognosis techniques are of great significance in ensuring the normal operation of the fuel cellmore » and preventing or predicting its likely abrupt and catastrophic failure.« less

On stabilization of field emission and increase in the current density of planar nanostructures with DLC films

NASA Astrophysics Data System (ADS)

Yakunin, Alexander N.; Aban'shin, Nikolay P.; Avetisyan, Yuri A.; Akchurin, Georgy G.; Loginov, Alexander P.; Mosiyash, Denis S.; Akchurin, Garif G.

2018-04-01

The paper provides a justification and a comparative analysis of the scaling directions of the developed and investigated planar triode field emission cathode unit with the aim of increasing the maximum field current density up to 0.75 A-cm-2 without sacrificing durability. The design features of the vacuum device with a planar structure provided low-voltage control - at 150 V in the mode of long-term durability and not more than 250 V in the mode of the maximum permissible emission current.

Effect of a functional monomer (MDP) on the enamel bond durability of single-step self-etch adhesives.

PubMed

Tsuchiya, Kenji; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsubota, Keishi; Tsujimoto, Akimasa; Berry, Thomas P; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

2016-02-01

The present study aimed to determine the effect of the functional monomer, 10-methacryloxydecyl dihydrogen phosphate (MDP), on the enamel bond durability of single-step self-etch adhesives through integrating fatigue testing and long-term water storage. An MDP-containing self-etch adhesive, Clearfil Bond SE ONE (SE), and an experimental adhesive, MDP-free (MF), which comprised the same ingredients as SE apart from MDP, were used. Shear bond strength (SBS) and shear fatigue strength (SFS) were measured with or without phosphoric acid pre-etching. The specimens were stored in distilled water for 24 h, 6 months, or 1 yr. Although similar SBS and SFS values were obtained for SE with pre-etching and for MF after 24 h of storage in distilled water, SE with pre-etching showed higher SBS and SFS values than MF after storage in water for 6 months or 1 yr. Regardless of the pre-etching procedure, SE showed higher SBS and SFS values after 6 months of storage in distilled water than after 24 h or 1 yr. To conclude, MDP might play an important role in enhancing not only bond strength but also bond durability with respect to repeated subcritical loading after long-term water storage. © 2015 Eur J Oral Sci.

Adjuvant-enhanced CD4 T Cell Responses are Critical to Durable Vaccine Immunity.

PubMed

Martins, Karen A O; Cooper, Christopher L; Stronsky, Sabrina M; Norris, Sarah L W; Kwilas, Steven A; Steffens, Jesse T; Benko, Jacqueline G; van Tongeren, Sean A; Bavari, Sina

2016-01-01

Protein-based vaccines offer a safer alternative to live-attenuated or inactivated vaccines but have limited immunogenicity. The identification of adjuvants that augment immunogenicity, specifically in a manner that is durable and antigen-specific, is therefore critical for advanced development. In this study, we use the filovirus virus-like particle (VLP) as a model protein-based vaccine in order to evaluate the impact of four candidate vaccine adjuvants on enhancing long term protection from Ebola virus challenge. Adjuvants tested include poly-ICLC (Hiltonol), MPLA, CpG 2395, and alhydrogel. We compared and contrasted antibody responses, neutralizing antibody responses, effector T cell responses, and T follicular helper (Tfh) cell frequencies with each adjuvant's impact on durable protection. We demonstrate that in this system, the most effective adjuvant elicits a Th1-skewed antibody response and strong CD4 T cell responses, including an increase in Tfh frequency. Using immune-deficient animals and adoptive transfer of serum and cells from vaccinated animals into naïve animals, we further demonstrate that serum and CD4 T cells play a critical role in conferring protection within effective vaccination regimens. These studies inform on the requirements of long term immune protection, which can potentially be used to guide screening of clinical-grade adjuvants for vaccine clinical development.

Evaluation of PCC long-term durability using intermediate sized gravels to optimize mix gradations.

DOT National Transportation Integrated Search

2010-04-01

With the implementation of the 2000 Q-MC specification, an incentive is provided to produce an optimized gradation to improve placement characteristics. Also, specifications for slip-formed barrier rail have changed to require an optimized gradation....

Durability and smart condition assessment of ultra-high performance concrete in cold climates.

DOT National Transportation Integrated Search

2016-12-31

The goals of this study were to develop ecological ultra-high performance concrete (UHPC) with local materials and supplementary cementitious materials and to evaluate the long-term performance of UHPC in cold climates using effective mechanical test...

Surface resistivity as an alternative for rapid chloride permeability test of hardened concrete.

DOT National Transportation Integrated Search

2015-03-01

Kansas experiences harsh winters that require frequent use of de-icing salts, making it critical to the long-term : durability of concrete structures that the permeability is kept under control. Under current KDOT specification, the : Rapid Chloride ...

Long-term durability of geosynthetics based on exhumed samples from construction projects

DOT National Transportation Integrated Search

2001-04-01

This report presents the results of mechanical and chemical tests on 24 retrieved geosynthetics from 12 sites, across the United States and provides a baseline databank of mechanical and chemical properties of many commonly used geosynthesis in trans...

Safety and Durability of Effect with Long-Term, Open-Label Droxidopa Treatment in Patients with Symptomatic Neurogenic Orthostatic Hypotension (NOH303).

PubMed

Isaacson, Stuart; Shill, Holly A; Vernino, Steven; Ziemann, Adam; Rowse, Gerald J

2016-10-19

Neurogenic orthostatic hypotension (nOH) is associated with insufficient norepinephrine release in response to postural change. The objective of this study was to evaluate the long-term safety and durability of efficacy of the norepinephrine precursor droxidopa in patients with symptomatic nOH. This multinational study consisted of 3 sequential phases: a 3-month open-label droxidopa treatment phase followed by a 2-week double-blind, placebo-controlled withdrawal phase, and a 9-month open-label extension phase in which all patients received droxidopa. Patients were adults diagnosed with symptomatic nOH associated with Parkinson's disease, multiple system atrophy, pure autonomic failure, dopamine β-hydroxylase deficiency, or nondiabetic autonomic neuropathy. Efficacy was evaluated using patient- and investigator-reported questionnaire responses and the orthostatic standing test. Safety was assessed through adverse event (AE) reports and vital signs. A total of 102 patients received treatment with droxidopa. Initial improvements from baseline in patient-reported nOH symptom severity and impact on daily activities, evaluated using the Orthostatic Hypotension Questionnaire, exceeded 50% and were maintained throughout the 12-month study. Decreased nOH severity was also reflected in clinician and patient ratings on the Clinical Global Impression questionnaire. Standing systolic and diastolic blood pressures were increased from baseline throughout the study with droxidopa treatment. The most frequently reported AEs were falls, urinary tract infection, and headache. There was a low incidence (≤2%) of cardiac AEs (eg, first-degree atrioventricular block, supraventricular extrasystoles). Long-term, open-label treatment with droxidopa for up to 12 months was generally well tolerated and provided durable improvements in nOH signs and symptoms.

Effects of surface preparation on the long-term durability of adhesively bonded composite joints

NASA Astrophysics Data System (ADS)

Bardis, Jason Dante

The long-term durability of adhesively bonded composite joints is critical to modern aircraft structures, which are increasingly adopting bonding as an alternative option to mechanical fastening. The effects of the surface preparation of the adherends are critical, affecting initial strength, long-term durability, fracture toughness, and failure modes of bonded joints. In this study, several potential factors are evaluated, with focus on the following: (1) Effects of possible chemical contamination from release fabrics, release films, and peel plies during adherend cure. (2) Chemical and mechanical effects of abrasion on the fracture toughness and failure mode. (3) Characterization of paste and film adhesives. There are several standard test methods used to evaluate specimen fracture, but the majority concentrate on bonded metals and interlaminar composite fracture. Testing concentrated on mode I tests; a custom double cantilever beam specimen was devised and utilized, and two forms of a wedge crack test (traveling and static) were also used. Additionally, single lap shear tests were run to contrast the mode I tests. Non-destructive testing included X-ray photography of crack fronts, energy dispersive spectroscopy and X-ray photoelectron spectroscopy surface chemistry analyses, and scanning electron microscope imaging of prepared surfaces. All mode I test methods tended to be in agreement in the ranking of different surface preparation methods. Test results revealed that release agents deposited on adherend surfaces during their cure cycle prevented proper adhesion. While mechanical abrasion did improve their fracture toughness and lower their contamination greatly, the test values did not reach the levels of samples that were not contaminated before bonding, and the interfacial modes of failure did not always change to desirable modes.

Durability of Therapeutic Response With Long-Term Aripiprazole Lauroxil Treatment Following Successful Resolution of an Acute Episode of Schizophrenia.

PubMed

McEvoy, Joseph P; Risinger, Robert; Mykhnyak, Serhiy; Du, Yangchun; Liu, Chih-Chin; Stanford, Arielle D; Weiden, Peter J

To evaluate durability of therapeutic effect of long-term treatment with aripiprazole lauroxil in patients with schizophrenia following successful treatment of an acute psychotic episode. This post hoc analysis assessed long-term outcomes for a subgroup of patients who entered a 52-week extension study after being successfully stabilized with one of 2 doses of aripiprazole lauroxil (441 or 882 mg) in a pivotal 12-week, placebo-controlled, randomized clinical trial. Durability of therapeutic effect was measured by the proportion of patients completing the 1-year course of aripiprazole lauroxil, the trajectories of the Positive and Negative Syndrome Scale (PANSS) total and the Clinical Global Impression-Severity (CGI-S) item scores beyond the first 12 weeks, and the likelihood of remission at any follow-up point. In total, 181 patients treated with aripiprazole lauroxil entered the extension study; 73% and 66% of patients from the 441 mg and 882 mg groups, respectively, completed all 13 aripiprazole lauroxil treatments scheduled every 4 weeks over 52 weeks. Both groups continued on a positive trajectory of symptom improvements (P < .0001 for reductions in PANSS total and CGI-S scores from week 12 to end of follow-up). Most patients (74% and 68% in the aripiprazole lauroxil 441 mg and 882 mg groups, respectively) achieved remission during follow-up. These post hoc analyses of a subgroup of patients demonstrate the continued therapeutic efficacy of aripiprazole lauroxil after successful treatment of an acute episode of schizophrenia. Both the 441 mg and 882 mg groups had similar retention rates, degree of symptom improvement, and likelihood of remission. ClinicalTrials.gov identifier: NCT01469039; European Clinical Trials Database (EudraCT) numbers: 2012-003445-15 and 2012-003996-20​​​​. © Copyright 2017 Physicians Postgraduate Press, Inc.

Long-term strength determination for cooled blades made of monocrystalline superalloys

NASA Astrophysics Data System (ADS)

Getsov, L. B.; Semenov, A. S.; Besschetnov, V. A.; Grishchenko, A. I.; Semenov, S. G.

2017-04-01

For the manufacture of blades for modern gas-turbine installations, monocrystalline alloys are used. Traditional methods for the calculation of stressed-deformed state and safety factors for these alloys developed and verified for polycrystalline materials need to be adjusted. This paper deals with methodological principles for an approach to the solving of the problem concerning a finite-element determination of the long-term static strength for cooled monocrystalline blades employed in gas-turbine installations based on the use of two different models (phenomenological and micromechanical) considering the inelastic deformation of monocrystalline superalloys. An analysis has been performed for the distribution of Schmid factors in the spherical triangle for primary and secondary octahedral and cubic slip systems. Calculations are performed using Larson-Miller's parametric dependences taking into account the crystallographic orientation of the material. A determination procedure for the anisotropy coefficients of long-term strength is described based on data for different orientations. A comparative analysis of the results of finite-element calculations made using phenomenological and micromechanical (crystallographic) creep models for the long-term static strength of cooled monocrystalline blades used in a gas-turbine engine has been performed. It is shown that the location of the most loaded sections of such a blade coincide with the results of calculations according to these models. It has been found that the micromechanical deformation model results in the obtaining of the most conservative estimate for the long-term strength of turbine blades made of monocrystalline alloys. It is shown that the calculations using models for materials with isotropic properties can produce considerable errors in determining the durability of the blades. The possibility is considered for using 1D-, 2D-, and 3D-models for turbine monocrystalline blades in the determination of their durability parameters.

Food elimination diets are effective for long-term treatment of adults with eosinophilic oesophagitis.

PubMed

Reed, C C; Fan, C; Koutlas, N T; Shaheen, N J; Dellon, E S

2017-11-01

Limited data describe the long-term efficacy of dietary elimination in eosinophilic oesophagitis (EoE). To assess the long-term outcomes of food elimination diets for treatment of adults with EoE. We conducted a retrospective cohort study at our centre analysing all EoE patients receiving a food elimination diet without concomitant steroids. Baseline data were abstracted using standardised collection forms. Follow-up data from a mean 24.9-month period were collected for patients with a histological response to a food elimination diet during and after food reintroduction. The main outcomes were symptomatic, endoscopic and histological responses. Of 52 patients, 18 received a 6-food food elimination diet, 32 received targeted diet, and two received a 6-food food elimination diet with targeted elimination. There were 21 (40%) patients with an initial histological response. Responders reported less dysphagia after treatment (95% baseline vs 11%; P = .001) and at the end of follow-up (95% baseline vs 33%; P = .008). Significant and durable endoscopic improvements were recorded at the same time points: Endoscopic reference score: 3.2 vs 0.7; P = .001; and 3.2 vs 1.7; P = .06. Histological findings improved after the most restrictive diet in responders (49.8 vs 4.1 eosinophils per high-power field; P = .001) and remained suppressed in the 10 initial responders maintaining compliance at the end of follow-up (5.2 eosinophils per high-power field). Among EoE patients responding to a food elimination diet and remaining adherent, maintenance dietary therapy produced durable long-term symptomatic, endoscopic and histological disease control. These long-term data confirm that a food elimination diet is an effective maintenance treatment option in select adults with EoE. © 2017 John Wiley & Sons Ltd.

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

Temperature induced effects on the durability of MR fluids

NASA Astrophysics Data System (ADS)

Wiehe, A.; Kieburg, C.; Maas, J.

2013-02-01

Although commercial MR fluids exist for quite some time now and the feasibility as well as the advantages of the MR technology have been demonstrated for several applications by a variety of MR actuator prototypes, a sustainable market break-through of brake and clutch applications utilizing the shear mode is still missing. Essential impediments are the marginal knowledge about the durability of the MR technology. To overcome this situation, a long-term measurement system was developed for the durability analysis of MR fluid formulations within a technical relevant scale with respect to the volume of MR fluid and the transmitted torque. The focus of the presented series of measurements is given to the analysis of temperature induced effects on the durability. In this context four different failure indicators can be distinguished, namely an apparent negative viscosity, deviations in torque data obtained from different measurements as well as a pressure increase and a drop in the on-state torque. The measurement data of the present durability experiments indicate a significant dependency of the attainable energy intake density on the temperature. The aim of such durability tests is to establish a reliable data base for the industry to estimate the life-time of MR devices.

Crosslink Density and Molecular Weight Effects on the Viscoelastic Response of a Glassy High-Performance Polyimide

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.

2001-01-01

Durability and long-term performance are among the primary concerns for the use of advanced polymer matrix composites (PMCs) in modern aerospace structural applications. For a PMC subJected to long-term exposure at elevated temperatures. the viscoelastic nature of the polymer matrix will contribute to macroscopic changes in composite stiffness, strength and fatigue life. Over time. changes in the polymer due to physical aging will have profound effects on tile viscoelastic compliance of the material, hence affecting its long-term durability. Thus, the ability to predict material performance using intrinsic properties, such as crosslink density and molecular weight, would greatly enhance the efficiency of design and development of PMCs. The objective of this paper is to discuss and present the results of an experimental study that considers the effects of crosslink density, molecular weight and temperature on the viscoelastic behavior including physical aging of an advanced polymer. Five distinct variations in crosslink density were used to evaluate the differences in mechanical performance of an advanced polyimide. The physical aging behavior was isolated by conducting sequenced, short-term isothermal creep compliance tests in tension. These tests were performed over a range of sub-glass transition temperatures. The material constants, material master curves and physical aging-related parameters were evaluated as a function of temperature crosslink density and molecular weight using time-temperature and time-aging time superposition techniques.

Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: Recent Advances and Future Directions

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

This presentation briefly reviews the SiC/SiC major environmental and environment-fatigue degradations encountered in simulated turbine combustion environments, and thus NASA environmental barrier coating system evolution for protecting the SiC/SiC Ceramic Matrix Composites for meeting the engine performance requirements. The presentation will review several generations of NASA EBC materials systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. This paper will also focus on the performance requirements and design considerations of environmental barrier coatings for next generation turbine engine applications. The current development emphasis is placed on advanced NASA candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be briefly discussed.

FRP reinforcement for concrete: performance assessment and new construction : volume I: Sierrita De La Cruz Creek bridge.

DOT National Transportation Integrated Search

2016-07-01

Glass fiber reinforced polymer (GFRP) composites are emerging as a feasible economical solution to eliminate the : corrosion problem of steel reinforcements in the concrete industry. Confirmation of GFRP long-term durability is crucial : to extend it...

Phase 1 report on the development of predictive model for bridge deck cracking and strength development.

DOT National Transportation Integrated Search

2009-01-01

Early-age cracking, typically caused by drying shrinkage (and often coupled with autogenous and thermal : shrinkage), can have several detrimental effects on long-term behavior and durability. Cracking can also provide : ingress of water that can dri...

Surface resistivity as an alternative for rapid chloride permeability test of hardened concrete : [technical summary].

DOT National Transportation Integrated Search

2015-03-01

Kansas experiences harsh winters that require frequent use of de-icing salts, making it : critical to the long-term durability of concrete structures that the permeability is kept : under control. Under current KDOT specification, the Rapid Chloride ...

Prediction of fracture toughness and durability of adhesively bonded composite joints with undesirable bonding conditions

NASA Astrophysics Data System (ADS)

Musaramthota, Vishal

Advanced composite materials have enabled the conventional aircraft structures to reduce weight, improve fuel efficiency and offer superior mechanical properties. In the past, materials such as aluminum, steel or titanium have been used to manufacture aircraft structures for support of heavy loads. Within the last decade or so, demand for advanced composite materials have been emerging that offer significant advantages over the traditional metallic materials. Of particular interest in the recent years, there has been an upsurge in scientific significance in the usage of adhesively bonded composite joints (ABCJ's). ABCJ's negate the introduction of stress risers that are associated with riveting or other classical techniques. In today's aircraft transportation market, there is a push to increase structural efficiency by promoting adhesive bonding to primary joining of aircraft structures. This research is focused on the issues associated with the durability and related failures in bonded composite joints that continue to be a critical hindrance to the universal acceptance of ABCJ's. Of particular interest are the short term strength, contamination and long term durability of ABCJ's. One of the factors that influence bond performance is contamination and in this study the influence of contamination on composite-adhesive bond quality was investigated through the development of a repeatable and scalable surface contamination procedure. Results showed an increase in the contaminant coverage area decreases the overall bond strength significantly. A direct correlation between the contaminant coverage area and the fracture toughness of the bonded joint was established. Another factor that influences bond performance during an aircraft's service life is its long term strength upon exposure to harsh environmental conditions or when subjected to severe mechanical loading. A test procedure was successfully developed in order to evaluate durability of ABCJ's comprising severe environmental conditioning, fatiguing in ambient air and a combination of both. The bonds produced were durable enough to sustain the tests cases mentioned above when conditioned for 8 weeks and did not experience any loss in strength. Specimens that were aged for 80 weeks showed a degradation of 10% in their fracture toughness when compared to their baseline datasets. The effect of various exposure times needs to be further evaluated to establish the relationship of durability that is associated with the fracture toughness of ABCJ's.

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.

Extremely Durable, Flexible Supercapacitors with Greatly Improved Performance at High Temperatures.

PubMed

Kim, Sung-Kon; Kim, Hae Jin; Lee, Jong-Chan; Braun, Paul V; Park, Ho Seok

2015-08-25

The reliability and durability of energy storage devices are as important as their essential characteristics (e.g., energy and power density) for stable power output and long lifespan and thus much more crucial under harsh conditions. However, energy storage under extreme conditions is still a big challenge because of unavoidable performance decays and the inevitable damage of components. Here, we report high-temperature operating, flexible supercapacitors (f-SCs) that can provide reliable power output and extreme durability under severe electrochemical, mechanical, and thermal conditions. The outstanding capacitive features (e.g., ∼40% enhancement of the rate capability and a maximum capacitances of 170 F g(-1) and 18.7 mF cm(-2) at 160 °C) are attributed to facilitated ion transport at elevated temperatures. Under high-temperature operation and/or a flexibility test in both static and dynamic modes at elevated temperatures >100 °C, the f-SCs showed extreme long-term stability of 100000 cycles (>93% of initial capacitance value) and mechanical durability after hundreds of bending cycles (at bend angles of 60-180°). Even at 120 °C, the versatile design of tandem serial and parallel f-SCs was demonstrated to provide both desirable energy and power requirements at high temperatures.

NiCrNx interlayer thickness dependence of spectral performance and environmental durability of protected-silver mirrors

NASA Astrophysics Data System (ADS)

Xu, Xu; Li, Bincheng; He, Wenyan; Wang, Changjun; Wei, Ming

2018-04-01

Gemini-style protected-silver mirror (Sub / NiCrNx / Ag / NiCrNx / SiNx / Air) is a suitable choice for optical instruments requiring both long-term environmental durability and high broadband reflectance. Three Gemini-style protected-silver mirrors with NiCrNx interlayer thicknesses between 0.1 and 0.6 nm were prepared by magnetron sputtering, and the dependences of spectral properties and environmental durability of these protected-silver mirrors on the thickness of NiCrNx interlayer between the silver layer and SiNx layer were investigated in-depth. The reflectance, transmittance and total scattering loss measurements, optical microscope, and scanning electron microscope imaging were employed to characterize the spectral properties and surface morphology, and accelerated environmental tests, including humidity test and salt fog test, were applied to investigate the environmental durability. The experimental results showed that both optical and corrosion-resistant properties of protected-silver mirrors were NiCrNx interlayer thickness dependent, and an optimum NiCrNx interlayer thickness should be ˜0.3 nm for Gemini-style protected-silver mirrors to have reasonably both high reflectance in a broadband spectral range from visible to far infrared and good corrosion resistance for long-lifetime applications in harsh environments.

Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

2016-01-01

This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

Overview of ORNL/NRC programs addressing durability of concrete structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1994-06-01

The role of reinforced concrete relative to its applications as either safety-related structures in nuclear power or engineered barriers of low-level radioactive waste disposal facilities is described. Factors that can affect the long-term durability of reinforced concrete are identified. Overviews are presented of the Structural Aging Program, which is addressing the aging management of safety-related concrete structures in nuclear power plants, and the Permeability Test Methods and Data Program, which is identifying pertinent data and information for use in performance assessments of engineered barriers for low-level radioactive waste disposal.

Thermal Conductivity and Sintering Behavior of Advanced Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2002-01-01

Advanced thermal barrier coatings, having significantly reduced long-term thermal conductivities, are being developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and physical vapor-deposited thermal barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

Nonsurgical Outpatient Therapies for the Management of Female Stress Urinary Incontinence: Long-Term Effectiveness and Durability

PubMed Central

Davila, G. Willy

2011-01-01

Objective. To evaluate long-term effectiveness and safety of conservative and minimally invasive outpatient treatments for female stress urinary incontinence (SUI) through a review of the literature. Methods. PubMed was searched for reports on prospective clinical trials with at least 12-month follow-up of minimally invasive treatments, pelvic floor rehabilitation, or pharmacotherapy in women with SUI. Each report was examined for long-term rates of effectiveness and safety. Results. Thirty-two clinical trial reports were included. Prospective long-term studies of pelvic floor rehabilitation were limited but indicated significant improvements with treatment adherence for at least 12 months. Poor initial tolerability with duloxetine resulted in substantial discontinuation. Most patients receiving transurethral radiofrequency collagen denaturation or urethral bulking agents reported significant long-term improvements, generally good tolerability, and safety. Conclusions. Conservative therapy is an appropriate initial approach for female SUI, but if therapy fails, radiofrequency collagen denaturation or bulking agents may be an attractive intermediate management step or alternative to surgery. PMID:21738529

Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

NASA Technical Reports Server (NTRS)

Lee, Kang N.

1999-01-01

Plasma-sprayed mullite (3Al2O3 central dot 2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon-based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface, Thus modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

NASA Technical Reports Server (NTRS)

Lee, Kang N.

2000-01-01

Plasma-sprayed mullite (3Al2O3.2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon -based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

A new kind of high durable traffic weighbridge based on FBG sensors

NASA Astrophysics Data System (ADS)

Zhou, Zhi; Liu, Jing; Li, Hui; Ou, Jinping

2005-05-01

Durability is the key problem of traditional traffic weighbridge based on electrical gauges. In this paper, a new kind of high durable traffic weighbridge based on FBG (Fiber Bragg Grating) sensors has been studied and developed. The principle of the smart FBG-weighbridge is based on that the traffic weight can be gotten from the deformation of the reinforced concrete beam with embedded FRP (Fiber Reinforced Polymer) - packaged FBG strain sensors. The FBG-based weighbridge is designed to be a reinforced concrete board supported by composite beams, and the truck load is shared by the composite beams. A 30-ton full scale FBG-based weighbridge has been set up, and the results from the tests and calibration analysis show that this kind of weighbridge features high durability, simplicity, convenience, low cost, etc. This new kind of FBG-based weighbridge shows good prospect in future to replace the traditional traffic weighbridge for long-term monitoring of traffic load.

FRP reinforcement for concrete : performance assessment and new construction volume I : Sierrita De La Cruz Creek bridge : final report.

DOT National Transportation Integrated Search

2016-07-01

Glass fiber reinforced polymer (GFRP) composites are emerging as a feasible economical solution to eliminate the corrosion problem of steel reinforcements in the concrete industry. Confirmation of GFRP long-term durability is crucial to extend its ap...

ASSESSMENT PROTOCOLS - DURABILITY OF PERFORMANCE OF A HOME RADON REDUCTION SYSTEM FOR SUB-SLAB DEPRESSURIZA- TION SYSTEMS

EPA Science Inventory

This handbook contains protocols that compare the immediate performance of subslab depressurization (SSD) mitigation system with performance months or years later. These protocols provide a methodology to test SSD radon mitigation systems in situ to determine long-term performanc...

Optimizing the durability of the coarse fraction of porous asphalt RAP for effective recycling

NASA Astrophysics Data System (ADS)

Holleran, Irina; Wilson, Douglas J.; Black, Philippa; Holleran, Glynn; Walubita, Lubinda F.

2017-09-01

Porous asphalt (PA) durability depends not only on the binder used to manufacture the mix, but also on the aggregates chosen, particularly the coarse fraction component. Aggregates for PA should be of the highest quality and highly durable to withstand the effects of weather and traffic. To recycle PA into a new PA mix, without compromising the long-term performance, the durability of the recovered aggregates from PA-derived reclaimed asphalt pavement (RAP) should be assessed alongside the aged binder properties. In this study, the Micro-Deval (MD) Abrasion test, combined with water absorption, was found to be a good predictor of asphalt mix performance for PA. Minerology of the aggregates is an important factor when setting limits for MD loss. New Zealand (NZ) aggregates are significantly younger in geological terms, and chemically and physically less stable compared to the aggregates used in many other countries. This is especially true for greywacke, the most used aggregate in NZ for road construction. If the MD limits reported in some literature are applied to NZ PA-derived RAP aggregates, poor performing material can be erroneously incorporated in asphalt mixes. Findings from this study contributes in understanding how PA-derived RAP can be recycled into new value PA mixes.

Electrochemically deposited conducting polymers for reliable biomedical interfacing materials: Formulation, mechanical characterization, and failure analysis

NASA Astrophysics Data System (ADS)

Qu, Jing

Conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. These polymers provide an improved interface compared to metal and semiconducting electrodes because of their ionic conductivity, relatively lower stiffness, and ability to incorporate biological molecules. Even though the signal transfer and biocompatibility of conjugated polymers are superior compared as the biointerfacing materials, the durability has been the weakest part for the long-term applications. Even though some efforts have been made to improve the durability of conjugated polymers, little quantitative information of the improved cohesion, adhesion and durability has been reported. In this thesis, the methods of improving the durability of conjugated polymer films, especially PEDOT, were investigated, including alternating the processing methods and components in synthesis. The 7-month in vivo testing showed that the durability of PEDOT films still needed to be improved. As a coating for biosignal transfer, the cohesion, adhesion and electrochemical stability of PEDOT are vital to determine the long-term performance. Not much information hd been developed around the cohesion and adhesion. A thin film cracking method was developed to measure the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT. The estimated Young’s modulus of the PEDOT films was 2.6 ± 1.4 GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56 ± 27 MPa. The effectiveness of crosslinker and adhesion promoter was demonstrated by this method. It was shown that 5 mole% addition of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283 ± 67 MPa, while the strain to failure remained about the same (2%). With the modification of EDOT-acid to the surface of stainless steel substrate, the interfacial shear strength was improved from 11.8 MPa to 32.5 MPa. To correlate the adhesion with the durability of PEDOT coatings, a tribology test was introduced. It was found that the durability of PEDOT on Au electrode was much exceptionally good, and even better than the adhesion promoted coatings with EDOT-acid on stainless steel and ITO substrates. The characterization method developed in this thesis made a critical difference in systematically comparing different materials, and provided valuable information for materials development and selection.

Efficacy and safety of a biodegradable polymer sirolimus-eluting stent in primary percutaneous coronary intervention: a randomized controlled trial

PubMed Central

Li, Qiang; Tong, Zichuan; Wang, Lefeng; Zhang, Jianjun; Ge, Yonggui; Wang, Hongshi; Li, Weiming; Xu, Li; Ni, Zhuhua

2013-01-01

Introduction With long-term follow-up, whether biodegradable polymer drug-eluting stents (DES) is efficient and safe in primary percutaneous coronary intervention (PCI) remains a controversial issue. This study aims to assess the long-term efficacy and safety of DES in PCI for ST-segment elevation myocardial infarction (STEMI). Material and methods A prospective, randomized single-blind study with 3-year follow-up was performed to compare biodegradable polymer DES with durable polymer DES in 332 STEMI patients treated with primary PCI. The primary end point was major adverse cardiac events (MACE) at 3 years after the procedure, defined as the composite of cardiac death, recurrent infarction, and target vessel revascularization. The secondary end points included in-segment late luminal loss (LLL) and binary restenosis at 9 months and cumulative stent thrombosis (ST) event rates up to 3 years. Results The rate of the primary end points and the secondary end points including major adverse cardiac events, in-segment late luminal loss, binary restenosis, and cumulative thrombotic event rates were comparable between biodegradable polymer DES and durable polymer DES in these 332 STEMI patients treated with primary PCI at 3 years. Conclusions Biodegradable polymer DES has similar efficacy and safety profiles at 3 years compared with durable polymer DES in STEMI patients treated with primary PCI. PMID:24482648

The chemical durability of tektites - A laboratory study and correlation with long-term corrosion behavior

NASA Technical Reports Server (NTRS)

Barkatt, A.; Boulos, M. S.; Barkatt, A.; Sousanpour, W.; Boroomand, M. A.; Macedo, P. B.; Okeefe, J. A.

1984-01-01

Leach tests carried out on tektite specimens (indochinites and australites) under high-dilution conditions show a common behavior characterized by low leach rates (0.00018 g/sq m per d, or 7.2 x 10 to the -12th m/d at 23 C) and an activation energy of (79,600 + or - 700 J/mol). The extent of selective leaching is very small, of the order of 10 to the -8th m. Extrapolation of test results over the lifetime of the tektites gives an excellent agreement with field observations on the extent of corrosion, and this is an important step in establishing the validity of laboratory tests as a basis for the development of models and predictions concerning long-term durabilities at least in the limiting case of high dilution or rapid flow. The results are also shown to be in agreement with various previous observations on the corrosion resistance of tektites. The chemical durability of tektites is observed to be consistent with their composition, highlighting requirements of high corrosion resistance in glasses; these requirements include a silica content in excess of 67 mol percent, an extremely low water content, and an alkali content which is low both absolutely and relative to the di- and poly-valent metal oxide levels. It is shown that artificial glasses which fulfil these criteria are no less corrosion-resistant than the corresponding natural glasses. These conclusions have bearing on the development, as well as on the evaluation, of glasses intended for very long service, such as radioactive waste vitrification media.

Long-term clinical outcomes of biodegradable polymer biolimus-eluting stents versus durable polymer everolimus-eluting stents in patients with coronary artery disease: three-year follow-up of the COMPARE II (Abluminal biodegradable polymer biolimus-eluting stent versus durable polymer everolimus-eluting stent) trial.

PubMed

Vlachojannis, Georgios J; Smits, Pieter C; Hofma, Sjoerd H; Togni, Mario; Vázquez, Nicolás; Valdés, Mariano; Voudris, Vassilis; Puricel, Serban; Slagboom, Ton; Goy, Jean-Jacques; den Heijer, Peter; van der Ent, Martin

2015-07-01

The aim of this analysis was to compare the long-term safety and efficacy of the biodegradable polymer biolimus-eluting stent (BES) with that of the durable polymer everolimus-eluting stent (EES). The COMPARE II study was a prospective, randomised, multicentre, all-comers trial in which 2,707 patients were randomly allocated (2:1) to BES or EES. The pre-specified endpoint at three years was major adverse cardiac events (MACE), a composite of cardiac death, non-fatal myocardial infarction (MI), or target vessel revascularisation (TVR). Moreover, the combined endpoint all-cause death or MI was analysed as a safety, and TVR as an efficacy measure. Three-year follow-up was available in 2,683 patients (99.1%). At three years, MACE occurred in 213 patients (11.9%) in the BES group and in 101 patients (11.1 %) in the EES group (p=0.57). The rate of the combined safety endpoint all-cause death or MI was 9.3% in the BES group vs. 8.4% (p=0.52), while the efficacy measure TVR was 7.6% in BES vs. 6.5% (p=0.27). Interestingly, definite stent thrombosis rates did not differ between groups (1.2% for BES vs. 0.8%, p=0.33). At three-year follow-up, MACE as well as safety and efficacy measures including stent thrombosis were not statistically different between the biodegradable polymer-coated BES and the durable polymer-coated EES. ClinicalTrials.gov Identifier: NCT01233453.

Long-term Durability of Immune Responses After Hepatitis A Vaccination Among HIV-Infected Adults

PubMed Central

Wilkins, Kenneth; Lee, Andrew W.; Grosso, Anthony; Landrum, Michael L.; Weintrob, Amy; Ganesan, Anuradha; Maguire, Jason; Klopfer, Stephanie; Brandt, Carolyn; Bradley, William P.; Wallace, Mark R.; Agan, Brian K.

2011-01-01

Background.  Vaccination provides long-term immunity to hepatitis A virus (HAV) among the general population, but there are no such data regarding vaccine durability among human immunodeficiency virus (HIV)–infected adults. Methods.  We retrospectively studied HIV-infected adults who had received 2 doses of HAV vaccine. We analyzed blood specimens taken at 1 year, 3 years, and, when available, 6–10 years postvaccination. HAV immunoglobulin G (IgG) values of ≥10 mIU/mL were considered seropositive. Results.  We evaluated specimens from 130 HIV-infected adults with a median age of 35 years and a median CD4 cell count of 461 cells/mm3 at or before time of vaccination. Of these, 49% had an HIV RNA load <1000 copies/mL. Initial vaccine responses were achieved in 89% of HIV-infected adults (95% confidence interval [CI], 83%–94%), compared with 100% (95% CI, 99%–100%) of historical HIV-uninfected adults. Among initial HIV-infected responders with available specimens, 90% (104 of 116; 95% CI, 83%–95%) remained seropositive at 3 years and 85% (63 of 74; 95% CI, 75%–92%) at 6–10 years. Geometric mean concentrations (GMCs) among HIV-infected adults were 154, 111, and 64 mIU/mL at 1, 3, and 6–10 years, respectively, compared with 1734, 687, and 684 mIU/mL among HIV-uninfected persons. Higher GMCs over time among HIV-infected adults were associated with lower log10 HIV RNA levels (β = −.12, P = .04). Conclusions.  Most adults with well-controlled HIV infections had durable seropositive responses up to 6–10 years after HAV vaccination. Suppressed HIV RNA levels are associated with durable HAV responses. PMID:21606540

Pyramiding, alternating or mixing: comparative performances of deployment strategies of nematode resistance genes to promote plant resistance efficiency and durability.

PubMed

Djian-Caporalino, Caroline; Palloix, Alain; Fazari, Ariane; Marteu, Nathalie; Barbary, Arnaud; Abad, Pierre; Sage-Palloix, Anne-Marie; Mateille, Thierry; Risso, Sabine; Lanza, Roger; Taussig, Catherine; Castagnone-Sereno, Philippe

2014-02-22

Resistant cultivars are key elements for pathogen control and pesticide reduction, but their repeated use may lead to the emergence of virulent pathogen populations, able to overcome the resistance. Increased research efforts, mainly based on theoretical studies, explore spatio-temporal deployment strategies of resistance genes in order to maximize their durability. We evaluated experimentally three of these strategies to control root-knot nematodes: cultivar mixtures, alternating and pyramiding resistance genes, under controlled and field conditions over a 3-years period, assessing the efficiency and the durability of resistance in a protected crop rotation system with pepper as summer crop and lettuce as winter crop. The choice of the resistance gene and the genetic background in which it is introgressed, affected the frequency of resistance breakdown. The pyramiding of two different resistance genes in one genotype suppressed the emergence of virulent isolates. Alternating different resistance genes in rotation was also efficient to decrease virulent populations in fields due to the specificity of the virulence and the trapping effect of resistant plants. Mixing resistant cultivars together appeared as a less efficient strategy to control nematodes. This work provides experimental evidence that, in a cropping system with seasonal sequences of vegetable species, pyramiding or alternating resistance genes benefit yields in the long-term by increasing the durability of resistant cultivars and improving the long-term control of a soil-borne pest. To our knowledge, this result is the first one obtained for a plant-nematode interaction, which helps demonstrate the general applicability of such strategies for breeding and sustainable management of resistant cultivars against pathogens.

Pyramiding, alternating or mixing: comparative performances of deployment strategies of nematode resistance genes to promote plant resistance efficiency and durability

PubMed Central

2014-01-01

Background Resistant cultivars are key elements for pathogen control and pesticide reduction, but their repeated use may lead to the emergence of virulent pathogen populations, able to overcome the resistance. Increased research efforts, mainly based on theoretical studies, explore spatio-temporal deployment strategies of resistance genes in order to maximize their durability. We evaluated experimentally three of these strategies to control root-knot nematodes: cultivar mixtures, alternating and pyramiding resistance genes, under controlled and field conditions over a 3-years period, assessing the efficiency and the durability of resistance in a protected crop rotation system with pepper as summer crop and lettuce as winter crop. Results The choice of the resistance gene and the genetic background in which it is introgressed, affected the frequency of resistance breakdown. The pyramiding of two different resistance genes in one genotype suppressed the emergence of virulent isolates. Alternating different resistance genes in rotation was also efficient to decrease virulent populations in fields due to the specificity of the virulence and the trapping effect of resistant plants. Mixing resistant cultivars together appeared as a less efficient strategy to control nematodes. Conclusions This work provides experimental evidence that, in a cropping system with seasonal sequences of vegetable species, pyramiding or alternating resistance genes benefit yields in the long-term by increasing the durability of resistant cultivars and improving the long-term control of a soil-borne pest. To our knowledge, this result is the first one obtained for a plant-nematode interaction, which helps demonstrate the general applicability of such strategies for breeding and sustainable management of resistant cultivars against pathogens. PMID:24559060

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.

Advanced composite structural concepts and materials technologies for primary aircraft structures: Advanced material concepts

NASA Technical Reports Server (NTRS)

Lau, Kreisler S. Y.; Landis, Abraham L.; Chow, Andrea W.; Hamlin, Richard D.

1993-01-01

To achieve acceptable performance and long-term durability at elevated temperatures (350 to 600 F) for high-speed transport systems, further improvements of the high-performance matrix materials will be necessary to achieve very long-term (60,000-120,000 service hours) retention of mechanical properties and damage tolerance. This report emphasizes isoimide modification as a complementary technique to semi-interpenetrating polymer networks (SIPN's) to achieve greater processibility, better curing dynamics, and possibly enhanced thermo-mechanical properties in composites. A key result is the demonstration of enhanced processibility of isoimide-modified linear and thermo-setting polyimide systems.

Development of a Long-Life-Cycle, Highly Water-Resistant Solar Reflective Retrofit Roof Coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polyzos, Georgios; Hunter, Scott; Sharma, Jaswinder

2016-03-04

Highly water-resistant and solar-reflective coatings for low-slope roofs are potentially among the most economical retrofit approaches to thermal management of the building envelope. Therefore, they represent a key building technology research program within the Department of Energy. Research efforts in industry and the Department of Energy are currently under way to increase long-term solar reflectance on a number of fronts. These include new polymer coatings technologies to provide longer-lasting solar reflectivity and improved test methodologies to predict long-term soiling and microbial performance. The focus on long-term improvements in soiling and microbial resistance for maximum reflectance does not address the singlemore » most important factor impacting the long-term sustainability of low-slope roof coatings: excellent water resistance. The hydrophobic character of asphaltic roof products makes them uniquely suitable for water resistance, but their low albedo and poor exterior durability are disadvantages. A reflective coating that maintains very high water resistance with increased long-term resistance to soiling and microbial activity would provide additional energy savings and extend roof service life.« less

PROTOCOL TO EVALUATE THE MOISTURE DURABILITY OF ENERGY-EFFICIENT WALLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boudreaux, Philip R; Pallin, Simon B; Hun, Diana E

Walls account for about 8% of the energy used in residential buildings. This energy penalty can be reduced with higher insulation levels and increased airtightness. However, these measures can compromise the moisture durability and long-term performance of wall assemblies because they can lead to lower moisture tolerance due to reduced drying potential. To avert these problems, a moisture durability protocol was developed to evaluate the probability that an energy-efficient wall design will experience mold growth. This protocol examines the effects of moisture sources in walls through a combination of simulations and lab experiments, uses the mold growth index as themore » moisture durability indicator, and is based on a probabilistic approach that utilizes stochastically varying input parameters. The simulation tools used include a new validated method for taking into account the effects of air leakage in wall assemblies This paper provides an overview of the developed protocol, discussion of the probabilistic simulation approach and describes results from the evaluation of two wall assemblies in Climate Zones 2, 4, and 6. The protocol will be used to supply builders with wall designs that are energy efficient, moisture durable and cost-effective.« less

Development and evaluation of a long-term, implantable, electrically actuated left ventricular assist system: THI/Gould LVAS.

PubMed

Norman, J C; McGee, M G; Fuqua, J M; Igo, S R; Turner, S A; Sterling, R; Urrutia, C O; Frazier, O H; Clay, W C; Chambers, J A

1983-02-01

A long-term, implantable, electrically actuated left ventricular assist system (THI/Gould LVAS) is being developed and characterized in vitro and in vivo for utilization in patients with end-stage heart disease. This system consists of five major components: a long-term, implantable blood pump (THI E-type ALVAD); an electrical-mechanical energy converter (Gould Model V); a control unit with batteries; a volume compensation system; and an external power supply and monitoring unit. Two of these components (blood pump and electrical-mechanical energy converter) have been integrated, and are undergoing chronic in vivo evaluations in calves. Thus far, 44 pneumatically and electrically actuated THI/Gould LVAS evaluations have been performed. This experience has resulted in greater than 6.5 years of actuation in vivo, with durations exceeding 1 year. System in vivo performance in terms of durability, mechanical reliability, hemodynamic effectiveness, and biocompatibility has been satisfactory. Demonstration of long-term (2-year) effectiveness in supporting the circulation is the ultimate goal.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

The objectives of this project are to determine the long-term chemical reactivity and mechanical durability of a fluidized version of Phillips Petroleum Company`s proprietary Z-SORB sorbent for the desulfurization of coal-derived gases in a high-pressure (20 atm) fluidized-bed reactor under simulated U-Gas conditions and at a moderate operating temperature of 538 degrees C.

Pallet part grading trainer

Treesearch

Deborah F. Cook; Philip A. Araman; Matthew F. Winn

2000-01-01

A computerized pallet grading training system was developed to facilitate the production of higher quality pallets. Higher quality pallets would be more durable and could be re-used many times, resulting in long-term savings. Schmoldt et al. (1993) evaluated the economic impact of grading and sorting pallet parts. They determined that higher quality pallets produced by...

A Randomized Trial of Telephone Psychotherapy and Pharmacotherapy for Depression: Continuation and Durability of Effects

ERIC Educational Resources Information Center

Ludman, Evette J.; Simon, Gregory E.; Tutty, Steve; Von Korff, Michael

2007-01-01

Randomized trial evidence and expert guidelines are mixed regarding the value of combined pharmacotherapy and psychotherapy as initial treatment for depression. This study describes long-term results of a randomized trial (N = 393) evaluating telephone-based cognitive-behavioral therapy (CBT) plus care management for primary care patients…

An Evaluation of the Generalization and Maintenance of Functional Communication and Self-Control Skills with Preschoolers

ERIC Educational Resources Information Center

Luczynski, Kevin C.; Hanley, Gregory P.; Rodriguez, Nicole M.

2014-01-01

The preschool life skills (PLS) program (Hanley, Heal, Tiger, & Ingvarsson, 2007; Luczynski & Hanley, 2013) involves teaching social skills as a means of decreasing and preventing problem behavior. However, achieving durable outcomes as children transition across educational settings depend on the generalization and long-term maintenance…

Effect of Prior Aging on Fatigue Behavior of IM7/BMI 5250-4 Composite at 191 C

DTIC Science & Technology

2007-06-01

6 Figure 4. Three stages of fatigue life cycle for general material ....................................... 9 Figure 5...calibration ........ 24 vii Figure 17. Omega thermocouple reader setup .................................................................. 26 Figure...cost and fleet readiness. To assure long- term durability and structural integrity of HTPMC components, reliable experimentally- based life -prediction

Long term follow-up of bifurcation aneurysms treated with braided stent assisted coiling and complex T- and Y- stent constructs.

PubMed

Cheung, Nicholas K; Chiu, Albert Hy; Cheung, Andrew; Wenderoth, Jason D

2018-06-01

Stent assisted coil embolization (SACE) of bifurcation aneurysms is challenging. Heterogeneous results have been achieved to date, but largely for laser cut stents. While braided stents offer multiple technical advantages, their long term efficacy has yet to be validated. To report the first long term 18 month results for the durability of bifurcation aneurysms treated with braided stents. Over a 4 year period, 59 consecutive patients with 60 bifurcation aneurysms underwent elective braided SACE across three Australian neurovascular centers. 17 of these aneurysms underwent T- or Y-shaped stent constructs. All patients had immediate, 6 month and 18 month clinical and radiological follow-up. Radiological assessment was made on modified Raymond-Roy occlusion scores while clinical assessment was based on the modified Rankin Scale. Subgroup analysis of 17 aneurysms treated with multi-stent constructs was conducted. 6 month follow-up data were available for 59 aneurysms and 18 month follow-up data for 58 aneurysms. Satisfactory aneurysm occlusion was achieved in 97% at inception and at 6 months, and 98% at 18 months. Good neurological outcomes were achieved in 95% at 18 months. Similar satisfactory results were achieved with the multi-stent construct cohort. Intraprocedural thromboembolic events were recorded in 5% and delayed events in 2%. Technical complications were found in 5%. All complication rate was 13%. Braided SACE was safe, efficacious, and durable at the long term 18 month follow-up, including for multi-stent constructs. Preliminary results indicate favorable clinical and radiological outcomes compared with laser cut stents. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Mid- and long-term outcomes of carotid-cavernous fistula endovascular management with Onyx and n-BCA: experience of a single tertiary center.

PubMed

Barber, Sean M; Rangel-Castilla, Leonardo; Zhang, Y Jonathan; Klucznik, Richard; Diaz, Orlando

2015-10-01

Endovascular therapy is the preferred treatment for most carotid-cavernous fistulas (CCFs). Early reports have documented excellent initial clinical and radiographic outcomes after embolization of CCFs with Onyx or n-butyl cyanoacrylate (n-BCA), but little evidence is available about the long-term durability of this technique. To characterize the long-term durability of CCF liquid embolization. The authors retrospectively reviewed a database of 24 CCFs in 21 consecutive patients who underwent Onyx or n-BCA embolization of a CCF from 2006 to 2013 at our institution. A total of 25 Onyx or n-BCA embolization procedures were attempted and 24 successfully completed during the study, resulting in complete or near-complete occlusion by the end of the study in all 24 CCFs (obliteration success, 100%). Attempted embolization in a single CCF failed initially, but was performed successfully at a later date by a different approach. None of the 24 CCFs recanalized, regrew, or required any further treatment subsequent to Onyx or n-BCA embolization throughout a mean 12.4 months of angiographic follow-up (range 1-36 months). Clinically significant complications were seen in three embolization procedures, including cranial nerve palsies (n=1), embolic infarct (n=1), and intraperitoneal hemorrhage (n=1). Early evidence has indicated that endovascular embolization with Onyx is relatively safe and effective at achieving an initial angiographic cure for CCFs. Results of our series suggest that angiographic and clinical outcomes of Onyx and n-BCA embolization remain stable at mid- and long-term follow-up. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Compact and Lightweight Sabatier Reactor for Carbon Dioxide Reduction

NASA Technical Reports Server (NTRS)

Junaedi, Christian; Hawley, Kyle; Walsh, Dennis; Roychoudhury, Subir; Abney, Morgan B.; Perry, Jay L.

2011-01-01

The utilization of CO2 to produce life support consumables, such as O2 and H2O, via the Sabatier reaction is an important aspect of NASA s cabin Atmosphere Revitalization System and In-Situ Resource Utilization architectures for both low-earth orbit and long-term manned space missions. In the current International Space Station (ISS) and other low orbit missions, metabolically-generated CO2 is removed from the cabin air and vented into space, resulting in a net loss of O2. This requires a continuous resupply of O2 via water electrolysis, and thus highlights the need for large water storage capacity. For long-duration space missions, the amount of life support consumables is limited and resupply options are practically nonexistent, thus atmosphere resource management and recycle becomes crucial to significantly reduce necessary O2 and H2O storage. Additionally, the potential use of the Martian CO2-rich atmosphere and Lunar regolith to generate life support consumables and propellant fuels is of interest to NASA. Precision Combustion, Inc. (PCI) has developed a compact, lightweight Microlith(Registered TradeMark)-based Sabatier (CO2 methanation) reactor which demonstrates the capability of achieving high CO2 conversion and near 100% CH4 selectivity at space velocities of 30,000-60,000 hr-1. The combination of the Microlith(Registered TradeMark) substrates and durable, novel catalyst coating permitted efficient Sabatier reactor operation that favors high reactant conversion, high selectivity, and long-term durability. This paper presents the reactor development and performance results at various operating conditions. Additionally, results from 100-hr durability tests and mechanical vibration tests are discussed.

The role of the Long Duration Exposure Facility in the development of space systems

NASA Technical Reports Server (NTRS)

Little, Sally A.

1992-01-01

The Long Duration Exposure Facility (LDEF) presents the international, aerospace community with an unprecedented opportunity to examine the synergistic, long term, space environmental effects on systems and materials. The analysis of the data within appropriate environmental contexts is essential to the overall process of advancing the understanding of space environmental effects needed for the continuing development of strategies to improve the reliability and durability of space systems and to effectively deal with the future challenges that new space initiatives will likely present.

Long-term evaluation of a nonpulsatile mechanical circulatory support system.

PubMed

Wakisaka, Y; Taenaka, Y; Chikanari, K; Nakatani, T; Tatsumi, E; Masuzawa, T; Nishimura, T; Takewa, Y; Ohno, T; Takano, H

1997-07-01

Antithrombogenicity of a centrifugal pump (CP) developed in our institute is provided by a central balancing hole (BH) in the impeller. A current CP, the National Cardiovascular Center (NCVC)-2, was ameliorated to improve antithrombogenicity, whereby the BH diameter was widened to improve self washout flow velocity, and an edge of the thrust bearing was rounded off to minimize flow separation. Effects of these modifications were assessed in a long-term in vivo experiment. The antithrombogenicity, hemolytic property, and mechanical durability of the NCVC-2 were investigated in 3 goats. The NCVC-2 was installed paracorporeally between the left atrium and the aorta and driven as long as possible at rotating speeds of about 2,800 rpm. The NCVC-2 ran for 50, 200, and 367+ days. The mean bypass flow rates were 6.8, 5.0, and 5.3 L/min, respectively. Creatinine, blood urea nitrogen (BUN), glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) did not increase until one week before termination. Plasma free hemoglobin was kept to a level less than 15 mg/dl, except for the last week of the second case. These results indicate that the NCVC-2 has excellent antithrombogenicity, an acceptable hemolytic property and the necessary durability for prolonged use.

Evaluation of long-term corrosion durability and self-healing ability of scratched coating systems on carbon steel in a marine environment

NASA Astrophysics Data System (ADS)

Zhao, Xia; Chen, Changwei; Xu, Weichen; Zhu, Qingjun; Ge, Chengyue; Hou, Baorong

2017-09-01

Defects in protective-coating systems on steel surfaces are inevitable in practical engineering applications. A composite coating system, including a primer, middle coat and topcoat, were used to protect carbon steel from corrosion in a marine environment. Two environmental additives, glass fibers and thiourea, were applied in the middle coat to modify the coating system. The long-term corrosion durability and self-healing ability of the scratched coating system were evaluated by multiple methods. Results of the electrochemical technologies indicated that the coating system that contained 0.5 wt.% fibers and 0.5 wt.% thiourea presented good corrosion protection and self-healing for carbon steel when immersed in 3.5% NaCl for 120 d. Evolution of localized corrosion factors with time, as obtained from the current distribution showed that fibers combined with thiourea could inhibit the occurrence of local corrosion in scratched coating systems and retarded the corrosion development significantly. Surface characterization suggested that adequate thiourea could be absorbed uniformly on fibers for a long time to play an important role in protecting the carbon steel. Finally, schematic models were established to demonstrate the action of fibers and thiourea on the exposed surface of the carbon steel and the scratched coating system in the entire deterioration process.

Fatigue behaviour analysis for the durability prequalification of strengthening mortars

NASA Astrophysics Data System (ADS)

Bocca, P.; Grazzini, A.; Masera, D.

2011-07-01

An innovative laboratory procedure used as a preliminary design stage for the pre-qualification of strengthening mortars applied to historical masonry buildings is described. In the analysis of the behaviour of masonry structures and their constituent materials, increasing importance has been assumed by the study of the long-term evolution of deformation and mechanical characteristics, which may be affected by both loading and environmental conditions. Through static and fatigue tests on mixed specimens historical brick-reinforced mortar it has been possible to investigate the durability of strengthening materials, in order to select, from a range of alternatives, the most suitable for the historical masonry. Cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of the historical brick-strengthening mortar system under static long-time loading. This methodology has proved useful in avoiding the errors associated with materials that are not mechanically compatible and guarantees the durability of strengthening work. The experimental procedure has been used effectively in the biggest restoration building site in Europe, the Royal Palace of Venaria, and it is in progress of carrying out at the Special Natural Reserve of the Sacro Monte di Varallo, in Piedmont (Italy).

Evaluation and Validation of Organic Materials for Advanced Stirling Convertors (ASCs): Overview

NASA Technical Reports Server (NTRS)

Shin, Euy-Sik Eugene

2015-01-01

Various organic materials are used as essential parts in Stirling Convertors for their unique properties and functionalities such as bonding, potting, sealing, thread locking, insulation, and lubrication. More efficient Advanced Stirling Convertors (ASC) are being developed for future space applications especially with a long mission cycle, sometimes up to 17 years, such as deep space exploration or lunar surface power or Mars rovers, and others. Thus, performance, durability, and reliability of those organics should be critically evaluated in every possible material-process-fabrication-service environment relations based on their mission specifications. In general, thermal stability, radiation hardness, outgassing, and material compatibility of the selected organics have been systematically evaluated while their process and fabrication conditions and procedures were being optimized. Service environment-simulated long term aging tests up to 4 years were performed as a function of temperature for durability assessment of the most critical organic material systems.

Quantitative trait loci from the host genetic background modulate the durability of a resistance gene: a rational basis for sustainable resistance breeding in plants.

PubMed

Quenouille, J; Paulhiac, E; Moury, B; Palloix, A

2014-06-01

The combination of major resistance genes with quantitative resistance factors is hypothesized as a promising breeding strategy to preserve the durability of resistant cultivar, as recently observed in different pathosystems. Using the pepper (Capsicum annuum)/Potato virus Y (PVY, genus Potyvirus) pathosystem, we aimed at identifying plant genetic factors directly affecting the frequency of virus adaptation to the major resistance gene pvr2(3) and at comparing them with genetic factors affecting quantitative resistance. The resistance breakdown frequency was a highly heritable trait (h(2)=0.87). Four loci including additive quantitative trait loci (QTLs) and epistatic interactions explained together 70% of the variance of pvr2(3) breakdown frequency. Three of the four QTLs controlling pvr2(3) breakdown frequency were also involved in quantitative resistance, strongly suggesting that QTLs controlling quantitative resistance have a pleiotropic effect on the durability of the major resistance gene. With the first mapping of QTLs directly affecting resistance durability, this study provides a rationale for sustainable resistance breeding. Surprisingly, a genetic trade-off was observed between the durability of PVY resistance controlled by pvr2(3) and the spectrum of the resistance against different potyviruses. This trade-off seemed to have been resolved by the combination of minor-effect durability QTLs under long-term farmer selection.

Measure Guideline. Wood Window Repair, Rehabilitation, and Replacement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, P.; Eng, P.

2012-12-01

This measure guideline provides information and guidance on rehabilitating, retrofitting, and replacing existing window assemblies in residential construction. The intent is to provide information regarding means and methods to improve the energy and comfort performance of existing wood window assemblies in a way that takes into consideration component durability, in-service operation, and long term performance of the strategies.

Measure Guideline: Window Repair, Rehabilitation, and Replacement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, P.

2012-12-01

This measure guideline provides information and guidance on rehabilitating, retrofitting, and replacing existing window assemblies in residential construction. The intent is to provide information regarding means and methods to improve the energy and comfort performance of existing wood window assemblies in a way that takes into consideration component durability, in-service operation, and long term performance of the strategies.

Chapter 14: Evaluating the Leaching of Biocides from Preservative-Treated Wood Products

Treesearch

Stan T. Lebow

2014-01-01

Leaching of biocides is an important consideration in the long term durability and any potential for environmental impact of treated wood products. This chapter discusses factors affecting biocide leaching, as well as methods of evaluating rate and quantity of biocide released. The extent of leaching is a function of preservative formulation, treatment methods, wood...

NREL Scientists Demonstrate Remarkable Stability in Perovskite Solar Cells

Science.gov Websites

environmentally stable, high-efficiency perovskite solar cell, bringing the emerging technology a step closer to needed to make the devices durable enough for long-term use. NREL's unencapsulated solar cell-a cell used Unencapsulated Perovskite Solar Cells for >1000 Hours of Operational Stability." "A solar cell in

Long term durability of wood-plastic composites made with chemically modified wood

Treesearch

Rebecca E. Ibach; Craig M. Clemons

2017-01-01

Wood-plastic composites (WPCs) have slower moisture sorption than solid wood, but over time moisture can impact the strength, stiffness, and decay of the composite. These changes will become increasingly important if WPCs are used in more challenging environments such as in ground-contact applications. There are several options for mitigating the moisture sorption of...

Sustainability and durability analysis of reinforced concrete structures

NASA Astrophysics Data System (ADS)

Horáková, A.; Broukalová, I.; Kohoutková, A.; Vašková, J.

2017-09-01

The article describes an assessment of reinforced concrete structures in terms of durability and sustainable development. There is a short summary of findings from the literature on evaluation methods for environmental impacts and also about corrosive influences acting on the reinforced concrete structure, about factors influencing the durability of these structures and mathematical models describing the corrosion impacts. Variant design of reinforced concrete structure and assessment of these variants in terms of durability and sustainability was performed. The analysed structure was a concrete ceiling structure of a parking house for cars. The variants differ in strength class of concrete and thickness of concrete slab. It was found that in terms of durability and sustainable development it is significantly preferable to use higher class of concrete. There are significant differences in results of concrete structures durability for different mathematical models of corrosive influences.

Incidental biasing of attention from visual long-term memory.

PubMed

Fan, Judith E; Turk-Browne, Nicholas B

2016-06-01

Holding recently experienced information in mind can help us achieve our current goals. However, such immediate and direct forms of guidance from working memory are less helpful over extended delays or when other related information in long-term memory is useful for reaching these goals. Here we show that information that was encoded in the past but is no longer present or relevant to the task also guides attention. We examined this by associating multiple unique features with novel shapes in visual long-term memory (VLTM), and subsequently testing how memories for these objects biased the deployment of attention. In Experiment 1, VLTM for associated features guided visual search for the shapes, even when these features had never been task-relevant. In Experiment 2, associated features captured attention when presented in isolation during a secondary task that was completely unrelated to the shapes. These findings suggest that long-term memory enables a durable and automatic type of memory-based attentional control. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Preliminary Assessment of Potential Habitat Composites' Durability when Exposed to a Long-Term Radiation Environment and Micrometeoroid Impacts

NASA Technical Reports Server (NTRS)

Rojdev, Kristina; Graves, Russell; Golden, John; Atwell, William; O'Rouke, Mary Jane; Hill, Charles; Alred, John

2011-01-01

NASA's exploration goals include extending human presence beyond low earth orbit (LEO). As a result, habitation for crew is a critical requirement for meeting this goal. However, habitats are very large structures that contain a multitude of subsystems to sustain human life over long-durations in space, and one of the key challenges has been keeping weight to a minimum in order to reduce costs. Thus, light-weight and multifunctional structural materials are of great interest for habitation. NASA has started studying polymeric composite materials as potential lightweight and multifunctional structural materials for use in long-duration spaceflight. However, little is known about the survivability of these materials when exposed to the space environment outside of LEO for long durations. Thus, a study has been undertaken to investigate the durability of composite materials when exposed to long-duration radiation. Furthermore, as an addition to the primary study, a secondary preliminary investigation has been started on the micrometeoroid and orbital debris (MMOD) susceptibility of these materials after radiation exposure. The combined effects of radiation and MMOD impacts are the focus of this paper.

Effect of the cellular structure on thermal conductivity of rigid closed-cell foam polymers during long-term aging

NASA Astrophysics Data System (ADS)

Dementyev, A. G.; Dementyev, M. A.; Zinger, P. A.; Metlyakova, I. R.

1999-03-01

The thermal conductivity of rigid closed-cell polyurethane foams during long-term aging has been studied. The similarity between the kinetics of changes in the physical and mechanical characteristics of PU foams on progressive aging is established, which is attributed to the effect of matrix destruction. It is found that rigid foams have cell walls of various strength, whose impact on the kinetics of changes in the physical characteristics of the foams during long-term aging is ascertained. The results of predicting the thermal conductivity of PU foams by the method of temperature-time analogy and establishing the limits of its application are discussed. The research presented is of interest both in determining the foam durability and in replacing freons by alternative, ecologically less harmful blowing agents.

Comparison of Conventional Varnishes with Nanolacke UV Varnish With Respect to Hardness and Adhesion Durability

PubMed Central

Kaygin, Bulent; Akgun, Emre

2008-01-01

The long-term durability of varnished wooden surfaces used in either indoors or outdoors environments depends on the resistance of varnish layers on these surfaces against potential physical, mechanical and chemical effects to which they may be exposed. In this study, “Nanolacke ultraviolet varnish”, developed by a Turkish dying and varnish industry company and widely accepted as a 21st century technology has been compared to other conventional varnish systems widely used in the industry in terms of dry film resistance properties. In this study, cellulosic, polyurethane, polyester, synthetic and Nanolacke ultraviolet varnish have been applied on beech (Fagus orientalis L.) and oak (Quercus robur L.) wood samples which had been prepared according to the industry standards. Then, the hardness and adhesion resistance of these layers have been determined according to ASTM D 4366 and ASTM D 3359-2 standards, respectively. PMID:19325763

Reducing chronic obstructive pulmonary disease readmissions: the role of the durable medical equipment provider.

PubMed

Messenger, Robert W

2012-01-01

Exacerbation and frequent rehospitalization in chronic obstructive pulmonary disease exacts a heavy toll on the US health care system. To address these issues, new initiatives have been proposed that are largely based on financial penalties to promote patient education and postdischarge care. However, as laudable as these goals are, improving outcomes in the chronic obstructive pulmonary disease population is more confounding than it may first appear. Chronic hypoxia, cognitive dysfunction, poor nutrition, and economic disadvantage are just a few of the challenges that require creative solutions and ongoing support. Case managers need to utilize all the potential products and services that can assist in improving outcomes for these patients. Durable medical equipment providers are often viewed as purveyors of medical equipment that offer little in the form of clinical support. However, in many cases these providers represent an overlooked resource that provides individualized, highly structured patient education and ongoing support programs. The challenge is in identifying those durable medical equipment providers that offer patients contemporary technology, and have both the resources and the commitment to provide patient support that is amenable to the goals of the hospital. This article reviews many of the confounding issues that contribute to the frequent rehospitalization of chronic obstructive pulmonary disease patients. Recommendations to improve patient education and oxygen therapy outcomes are provided along with suggestions to aid in the vetting of durable medical equipment providers. Acute care hospitals, long-term acute care hospitals, extended care facilities, integrated delivery systems. 1. An understanding of the complex variables that play in the management of chronic obstructive pulmonary disease will help the case manager to plan an effective course of care. 2. Case managers need to ensure that patients receive long-term oxygen technology that supports their lifestyle, promotes compliance, and ultimately achieves the desired outcomes. 3. Case managers must advocate for coordinated, ongoing patient education and stress the need for continuing reinforcement. 4. Case managers must ensure that patients under their care be matched with durable medical equipment providers that provide the technology and support that favors positive clinical outcomes.

High conductive, long-term durable, anhydrous proton conductive solid-state electrolyte based on a metal-organic framework impregnated with binary ionic liquids: Synthesis, characteristic and effect of anion

NASA Astrophysics Data System (ADS)

Chen, Hui; Han, Shu-Yan; Liu, Rui-Heng; Chen, Teng-Fei; Bi, Kai-Lun; Liang, Jian-Bo; Deng, Yu-Heng; Wan, Chong-Qing

2018-02-01

Incorporating ionic liquids (abbreviated as ILs) into porous metal-organic framework (MOF) to obtain ILs@MOF nanocomposites is documented as a feasible method to achieve new type of anhydrous proton conductor with high performance. We newly synthesized a series of ILs with different acid counter anions (R-SO3-) and their ILs@MOF hybrid materials, i.e. SA-EIMS@MIL-101, MSA-EIMS@MIL-101 and PTSA-EIMS@MIL-101 (SA = sulfate acid, MSA = methanesulfonate acid, PTSA = p-toluenesulfonate acid, EIMS = 1-(1-ethyl-3-imidazolium)propane-3-sulfonate). Such hybrid materials displayed as anhydrous proton conduction with long-term durability even heated at 150 °C open to air. σ value of SA-EIMS@MIL-101 is up to 1.89 × 10-3 S cm-1, being in the range of the most conductive MOF-based materials. MOF support exhibited favorable proton transport and long-term retention for ILs. Anion volumes of R-SO3- displayed significant effects on the proton conductivity of such hybrid ILs@MOF materials. The smaller the van der Waals volume of R-SO3- is, the higher the conductivity of ILs@MOF is. This work suggests that the combination of a variety of the incorporated ILs and a MOF framework would afford high proton transport and gives an idea to explore the safe, anhydrous, solid-state electrolyte for high temperature proton exchange membrane fuel cell.

Monopropellant engine investigation for space shuttle reaction control system. Volume 3: Improvement of metal foam for catalyst retention

NASA Technical Reports Server (NTRS)

1975-01-01

The retention of granular catalyst in a metal foam matrix was demonstrated to greatly increase the life capability of hydrazine monopropellant reactors. Since nickel foam used in previous tests was found to become degraded after long-term exposure the cause of degradation was examined and metal foams of improved durability were developed. The most durable foam developed was a rhodium-coated nickel foam. An all-platinum foam was found to be incompatible in a hot ammonia (hydrazine) environment. It is recommended to scale up the manufacturing process for the improved foam to produce samples sufficiently large for space shuttle APU gas generator testing.

All-inorganic large-area low-cost and durable flexible perovskite solar cells using copper foil as a substrate.

PubMed

Abdollahi Nejand, B; Nazari, P; Gharibzadeh, S; Ahmadi, V; Moshaii, A

2017-01-05

Here, a low-cost perovskite solar cell using CuI and ZnO as the respective inorganic hole and electron transport layers is introduced. Copper foil is chosen as a cheap and low-weight conductive substrate which has a similar work function to ITO. Besides, copper foil is an interesting copper atom source for the growth of the upper cuprous iodide layer on copper foil. A spray coating of a transparent silver nanowire electrode is used as a top contact. The prepared device shows a maximum power conversion efficiency of 12.80% and long-term durability providing an environmentally and market friendly perovskite solar cell.

Degradation modeling of high temperature proton exchange membrane fuel cells using dual time scale simulation

NASA Astrophysics Data System (ADS)

Pohl, E.; Maximini, M.; Bauschulte, A.; vom Schloß, J.; Hermanns, R. T. E.

2015-02-01

HT-PEM fuel cells suffer from performance losses due to degradation effects. Therefore, the durability of HT-PEM is currently an important factor of research and development. In this paper a novel approach is presented for an integrated short term and long term simulation of HT-PEM accelerated lifetime testing. The physical phenomena of short term and long term effects are commonly modeled separately due to the different time scales. However, in accelerated lifetime testing, long term degradation effects have a crucial impact on the short term dynamics. Our approach addresses this problem by applying a novel method for dual time scale simulation. A transient system simulation is performed for an open voltage cycle test on a HT-PEM fuel cell for a physical time of 35 days. The analysis describes the system dynamics by numerical electrochemical impedance spectroscopy. Furthermore, a performance assessment is performed in order to demonstrate the efficiency of the approach. The presented approach reduces the simulation time by approximately 73% compared to conventional simulation approach without losing too much accuracy. The approach promises a comprehensive perspective considering short term dynamic behavior and long term degradation effects.

The restoration of a maxillary central incisor fracture with the original crown fragment using a glass fiber-reinforced post: a clinical report.

PubMed

Durkan, Rukiye Kaplan; Ozel, M Birol; Celik, Davut; Bağiş, Bora

2008-12-01

This report describes an esthetic, conservative, and economical alternative restoration technique for a fractured central incisor using the patient's own tooth crown piece and a bondable reinforcement glass fiber. Although the long-term durability of this adhesive post core restoration remains unknown, it remains successful after 1 year.

Identifying Stem-like Cells Using Mitochondrial Membrane Potential | Center for Cancer Research

Cancer.gov

Therapies that are based on living cells promise to improve treatments for metastatic cancer and for many degenerative diseases. Lasting treatment of these maladies may require the durable persistence of cells. Long-term engraftment of cells – for months or years – and the generation of large numbers of progeny are characteristics of stem cells. Most approaches to isolate

Treatment for anal fissure: Is there a safe option?

PubMed

Brady, Justin T; Althans, Alison R; Neupane, Ruel; Dosokey, Eslam M G; Jabir, Murad A; Reynolds, Harry L; Steele, Scott R; Stein, Sharon L

2017-10-01

Surgeons often approach anal fissure with chemical denervation (Botulinum toxin, BT) instead of initial lateral internal sphincterotomy (LIS) due to concerns for long-term incontinence. We evaluated the characteristics and outcomes of patients who received BT or LIS. We performed a retrospective chart review of patients undergoing LIS and BT for anal fissure between 2009 and 2015. In 2015, a telephone survey was performed to evaluate durability, long-term incontinence and patient satisfaction. Ninety-four patients met criteria: 73 LIS and 21 BT. Age (BT 49 vs. LIS 52) was similar between groups (p = 1.0). Cleveland Clinic Fecal Incontinence (CCFI) score pre-intervention was higher in BT than LIS patients (2.1 vs. 0.4, p = 0.007) with fewer BT patients with perfect continence (50% vs. 88%). Telephone survey response was 61%. Fissure recurrence was significantly higher for BT than LIS patients (36% vs. 9%, p = 0.03). Patients undergoing LIS were less likely to recur. Both LIS and BT patients had some durable changes in continence raising the question of whether there is a safe technique. Copyright © 2017 Elsevier Inc. All rights reserved.

Durability and regeneration of activated carbon air-cathodes in long-term operated microbial fuel cells

NASA Astrophysics Data System (ADS)

Zhang, Enren; Wang, Feng; Yu, Qingling; Scott, Keith; Wang, Xu; Diao, Guowang

2017-08-01

The performance of activated carbon catalyst in air-cathodes in microbial fuel cells was investigated over one year. A maximum power of 1722 mW m-2 was produced within the initial one-month microbial fuel cell operation. The air-cathodes produced a maximum power >1200 mW m-2 within six months, but gradually became a limiting factor for the power output in prolonged microbial fuel cell operation. The maximum power decreased by 55% when microbial fuel cells were operated over one year due to deterioration in activated carbon air-cathodes. While salt/biofilm removal from cathodes experiencing one-year operation increased a limiting performance enhancement in cathodes, a washing-drying-pressing procedure could restore the cathode performance to its original levels, although the performance restoration was temporary. Durable cathodes could be regenerated by re-pressing activated carbon catalyst, recovered from one year deteriorated air-cathodes, with new gas diffusion layer, resulting in ∼1800 mW m-2 of maximum power production. The present study indicated that activated carbon was an effective catalyst in microbial fuel cell cathodes, and could be recovered for reuse in long-term operated microbial fuel cells by simple methods.

Disbonding effects on elastic wave generation and reception by bonded piezoelectric sensor systems

NASA Astrophysics Data System (ADS)

Blackshire, James L.; Martin, Steven A.; Na, Jeong K.

2007-04-01

Durable integrated sensor systems are needed for long-term health monitoring evaluations of aerospace systems. For legacy aircraft the primary means of implementing a sensor system will be through surface mounting or bonding of the sensors to the structure. Previous work has shown that the performance of surface-bonded piezo sensors can degrade due to environmental effects such as vibrations, temperature fluctuations, and substrate flexure motions. This performance degradation included sensor cracking, disbonding, and general loss of efficiency over time. In this research effort, the bonding state of a piezo sensor system was systematically studied to understand and improve the long-term durability and survivability of the sensor system. Analytic and computational models were developed and used to understand elastic wave generation and reception performance for various states of sensor disbond. Experimental studies were also conducted using scanning laser vibrometry, pitch-catch ultrasound, and pulse-echo ultrasound methods to understand elastic wave propagation effects in thin plate materials. Significant performance loss was observed for increasing levels of sensor disbond as well as characteristic frequency signatures which may be useful in understanding sensor performance levels for future structural health monitoring systems.

The effect of curing conditions on the durability of high performance concrete

NASA Astrophysics Data System (ADS)

Bumanis, G.; Bajare, D.

2017-10-01

This study researches compressive strength and durability of the high strength self-compacting concrete (SCC) impacted at early stage by the curing conditions. The mixture compositions of metakaolin containing waste and cenospheres as partial cement replacement (15 wt%) were compared to reference SCC with 100% cement. The specimens prepared in advance were demoulded 24h after casting of the SCC and the specific curing conditions were applied for up to 28 days: standard water curing at 20°C (i); indoor curing at 20°C, RH 60% (ii) and low temperature air curing (2°C) at RH 60% (iii). Results indicate that at early stage (14 days) indoor curing conditions increase compressive strength of the SCC whilst no strength loss has been detected even at a low temperature curing. The further strength gain has been substantially reduced for samples cured indoor and at a low temperature with significant variation observed for long term compressive strength (180 days). The metakaolin containing waste has proved to be an effective partial cement replacement and it has improved strength gain even at a low temperature curing. Meanwhile cenospheres have reduced the SCC strength and with no positive effect on strength observed within the standard term. Freeze-thaw durability and resistance to the chloride penetration have been improved for the SCC cured at low temperature. The SCC with metakaolin containing waste has proved to be the most durable thus demonstrating importance of effective micro filler use.

Falling Leaves Inspired ZnO Nanorods-Nanoslices Hierarchical Structure for Implant Surface Modification with Two Stage Releasing Features.

PubMed

Liao, Hang; Miao, Xinxin; Ye, Jing; Wu, Tianlong; Deng, Zhongbo; Li, Chen; Jia, Jingyu; Cheng, Xigao; Wang, Xiaolei

2017-04-19

Inspired from falling leaves, ZnO nanorods-nanoslices hierarchical structure (NHS) was constructed to modify the surfaces of two widely used implant materials: titanium (Ti) and tantalum (Ta), respectively. By which means, two-stage release of antibacterial active substances were realized to address the clinical importance of long-term broad-spectrum antibacterial activity. At early stages (within 48 h), the NHS exhibited a rapid releasing to kill the bacteria around the implant immediately. At a second stage (over 2 weeks), the NHS exhibited a slow releasing to realize long-term inhibition. The excellent antibacterial activity of ZnO NHS was confirmed once again by animal test in vivo. According to the subsequent experiments, the ZnO NHS coating exhibited the great advantage of high efficiency, low toxicity, and long-term durability, which could be a feasible manner to prevent the abuse of antibiotics on implant-related surgery.

Durability of Anti-Infective Effect of Long-Term Silicone Sheath Catheters Impregnated with Antimicrobial Agents

PubMed Central

Tcholakian, Robert K.; Raad, Issam I.

2001-01-01

This study was performed to test the long-term antimicrobial efficacy of impregnated silicone catheters comprising an antimicrobial layer sandwiched between an external surface sheath and a luminal surface silicone sheath. The design of the catheter permits the introduction of various antimicrobials in addition to anticoagulants or antifibrins in the antimicrobial layer and allows their gradual release over a period of months after insertion. The in vitro data presented show that the catheter can provide antimicrobial activity for 90 days, after being replated for 15 7-day cycles of replating. When the catheters were immersed in human serum and incubated at 37°C, they demonstrated significant antimicrobial activity after more than 325 days of incubation. The significant long-term in vitro antimicrobial activity observed may imply effective in vivo activity for almost 1 year after insertion and could serve as a cost-effective alternative to surgically implantable silicone catheters. PMID:11408213

Radionuclide Incorporation and Long Term Performance of Apatite Waste Forms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jianwei; Lian, Jie; Gao, Fei

2016-01-04

This project aims to combines state-of-the-art experimental and characterization techniques with atomistic simulations based on density functional theory (DFT) and molecular dynamics (MD) simulations. With an initial focus on long-lived I-129 and other radionuclides such as Cs, Sr in apatite structure, specific research objectives include the atomic scale understanding of: (1) incorporation behavior of the radionuclides and their effects on the crystal chemistry and phase stability; (2) stability and microstructure evolution of designed waste forms under coupled temperature and radiation environments; (3) incorporation and migration energetics of radionuclides and release behaviors as probed by DFT and molecular dynamics (MD) simulations;more » and (4) chemical durability as measured in dissolution experiments for long term performance evaluation and model validation.« less

Sensors Enable Plants to Text Message Farmers

NASA Technical Reports Server (NTRS)

2013-01-01

Long-term human spaceflight means long-term menu planning. Since every pound of cargo comes with a steep price tag, NASA has long researched technologies and techniques to allow astronauts to grow their own food, both on the journey and in some cases at their destination. Sustainable food technologies designed for space have resulted in spinoffs that improve the nutrition, safety, and durability of food on Earth. There are of course tradeoffs involved in making astronauts part-time farmers. Any time spent tending plants is time that can t be spent elsewhere: collecting data, exploring, performing routine maintenance, or sleeping. And as scarce as time is for astronauts, resources are even more limited. It is highly practical, therefore, to ensure that farming in space is as automated and precise as possible.

Freeze-Thaw Durability of Air-Entrained Concrete

PubMed Central

Shang, Huai-Shuai; Yi, Ting-Hua

2013-01-01

One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results. PMID:23576906

Freeze-thaw durability of air-entrained concrete.

PubMed

Shang, Huai-Shuai; Yi, Ting-Hua

2013-01-01

One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

Durability evaluation of reversible solid oxide cells

NASA Astrophysics Data System (ADS)

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

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. 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.

Durable and water-floatable ionic polymer actuator with hydrophobic and asymmetrically laser-scribed reduced graphene oxide paper electrodes.

PubMed

Kim, Jaehwan; Jeon, Jin-Han; Kim, Hyun-Jun; Lim, Hyuneui; Oh, Il-Kwon

2014-03-25

Ionic polymer actuators driven by electrical stimuli have been widely investigated for use in practical applications such as bioinspired robots, sensors, and biomedical devices. However, conventional ionic polymer-metal composite actuators have a serious drawback of poor durability under long-term actuation in open air, mainly because of the leakage of the inner electrolyte and hydrated cations through cracks in the metallic electrodes. Here, we developed a highly durable and water-floatable ionic polymer artificial muscle by employing hydrophobic and asymmetrically laser-scribed reduced graphene oxide paper electrodes (HLrGOP). The highly conductive, flexible, and cost-effective HLrGOP electrodes have asymmetrically smooth hydrophobic outer and rough inner surfaces, resulting in liquid-impermeable and water-floatable functionalities and strong bonding between an ionic polymer and the electrodes. More interestingly, the HLrGOP electrode, which has a unique functionality to prevent the leakage of the vaporized or liquid electrolyte and mobile ions during electrical stimuli, greatly contributes to an exceptionally durable ionic polymer-graphene composite actuator that is a prerequisite for practical applications in active biomedical devices, biomimetic robots, touch-feedback haptic systems, and flexible soft electronics.

Technology Solutions Case Study: Guidance on Taped Insulating Sheathing Drainage Planes

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The energy efficiency-based financial benefits of adding exterior insulation are well accepted by the building industry, and using exterior insulation as the drainage plane is the next logical step. This case study focuses on the field implementation of taped board insulation as the drainage plane in both new and retrofit residential applications, and provides information and recommendations for insulation contractors, general contractors, builders, remodelers, mechanical contractors, and homeowners. The order of work completed during home construction and retrofit improvements is important. Health and safety issues must be addressed first and are more important than durability issues, and durability issues aremore » more important than saving energy. Three significant items are required to make taped insulating sheathing a simple, long term, and durable drainage plane: first, horizontal joints should be limited or eliminated wherever possible; where a horizontal joint exists, use superior materials; and, frequent installation inspection and regular trade training are required to maintain proper installation.« less

Change or Durability? The Contribution of Metaconceptual Awareness in Preservice Early Childhood Teachers' Learning of Science Concepts

NASA Astrophysics Data System (ADS)

Saçkes, Mesut; Trundle, Kathy Cabe

2017-06-01

This longitudinal study examined the role of metaconceptual awareness in the change and the durability of preservice teachers' conceptual understandings over the course of several months. Sixteen preservice early childhood teachers participated in the study. Semi-structured interviews were conducted to reveal the participants' conceptual understandings of lunar phases (pre, post, and delayed-post) and level of metaconceptual awareness (delayed-post only). Based on the change and stability in participants' conceptual understandings from pre to post and from post to delayed-post interviews, participants' conceptual understandings were assigned into three groups that described the profile of their long-term conceptual understandings: " decay or stability", " continuous growth", and " growth and stability". The results indicated that participants in the " continuous growth" and " growth and stability" groups had significantly higher metaconceptual awareness scores than participants in the " decay or stability" group. The results provided evidence that metaconceptual awareness plays a more decisive role in the restructuring of conceptual understandings than the durability of conceptual understandings.

EFFECTS OF TEMPERATURE AND ENVIRONMENT ON MECHANICAL PROPERTIES OF TWO CHOPPED-FIBER AUTOMOTIVE STRUCTURAL COMPOSITES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruggles-Wrenn, M.B.

2003-10-06

The Durability of Lightweight Composite Structures Project was established at Oak Ridge National Laboratory (ORNL) by the U.S. Department of Energy to provide the experimentally-based, durability-driven design guidelines necessary to assure long-term structural integrity of automotive composite components. The initial focus of the ORNL Durability Project was on composite materials consisting of polyurethane reinforced with E-glass. Current focus of the project is on composite materials reinforced with carbon fibers. The primary purpose of this report is to provide the individual specimen test date. Basic mechanical property testing and results for two chopped-fiber composite materials, one reinforced with glass- and themore » other with carbon fiber are provided. Both materials use the same polyurethane matrix. Preforms for both materials were produced using the P4 process. Behavioral trends, effects of temperature and environment, and corresponding design knockdown factors are established for both materials. Effects of prior short-time loads and of prior thermal cycling are discussed.« less

Resin Systems and Chemistry-Degradation Mechanisms and Durability in Long-Term Durability of Polymeric Matrix Composites. Chapter 1

NASA Technical Reports Server (NTRS)

Hinkley, Jeffrey A.; Connell, John W.

2012-01-01

In choosing a polymer-matrix composite material for a particular application, a number of factors need to be weighed. Among these are mechanical requirements, fabrication method (e.g. press-molding, resin infusion, filament winding, tape layup), and use conditions. Primary among the environmental exposures encountered in aerospace structures are moisture and elevated temperatures, but certain applications may require resistance to other fluids and solvents, alkaline agents, thermal cycling, radiation, or rapid, localized heating (for example, lightning strike). In this chapter, the main classes of polymer resin systems found in aerospace composites will be discussed. Within each class, their responses to environmental factors and the associated degradation mechanisms will be reviewed.

Advanced Environmental Barrier Coatings Developed for SiC/SiC Composite Vanes

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.

2003-01-01

Ceramic components exhibit superior high-temperature strength and durability over conventional component materials in use today, signifying the potential to revolutionize gas turbine engine component technology. Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs) are prime candidates for the ceramic hotsection components of next-generation gas turbine engines. A key barrier to the realization of SiC/SiC CMC hot-section components is the environmental degradation of SiC/SiC CMCs in combustion environments. This is in the form of surface recession due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is a logical approach to achieve protection and long-term durability.

Durability of bends in high-temperature steam lines under the conditions of long-term operation

NASA Astrophysics Data System (ADS)

Katanakha, N. A.; Semenov, A. S.; Getsov, L. B.

2015-04-01

The article presents the results of stress-strain state computations and durability of bent and steeply curved branches of high-temperature steam lines carried out on the basis of the finite element method using the modified Soderberg formula for describing unsteady creep processes with taking the accumulation of damage into account. The computations were carried out for bends made of steel grades that are most widely used for manufacturing steam lines (12Kh1MF, 15Kh1M1F, and 10Kh9MFB) and operating at different levels of inner pressure and temperature. The solutions obtained using the developed creep model are compared with those obtained using the models widely used in practice.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aoki, K.; Fujii, N.; Kageyama, H.

Durability of selected hard materials as information preserving media has been studied, leading to some promising results. Several engraving experiments on the selected materials confirmed that characters and patterns can be expressed along with shading and gradation. Engraving experiments on durable artificial materials were carried out by applying laser technologies. By selecting appropriate materials and engraving methods, characters and patterns can be expressed along with shading and gradation. These technologies can be applied to not only documentary records but also to markers and monuments. Among the materials, silicon carbide, which has strong resistance against heat wear and chemical impacts, corrosionmore » resistance and wear resistance, showed satisfactory results in terms of accuracy. Thus, it is expected to be a promising material for the long-term record preservation. With respect to the density of characters in written records in the case of dot printing, it was estimated that, with 2-point characters, information totaling 6 to 8 pages of A-4 size can be engraved on a 10 cm x 10 cm plate. When a document that has 500 pages of A4 size paper is engraved on sintered silicon carbide plates, the total volume of recording media is evaluated as follows: - Size of plate: 10 cm x 10 cm; - Size of character to be engraved: 2-points ({approx} 0.7 mm; of readable size by naked eye or using a magnifying glass); - Number of pages of original document to be engraved on a plate: 8; - Number of pages of original document to be engraved on both sides of a plate: 16; - Number of plates needed for a series of document package: 500 / 16 = 32; - The thickness of a plate: 1 mm; - The total thickness of recording media: 32 mm; - Bulk of recording media preserving 500 pages of document: 10 cm x 10 cm x 32 cm. The examination has shown the possibility of long-term preservation of documentation records as a permanent system. A further examination is suggested concerning the assessment of the durability of the sintered silicon carbide plate against wear and chemical impacts. Preserving color pictures and photographs for a long-term duration is also proposed. In conclusion: We have proposed that the concept of a record preservation system is the combination of several different methods in order to impart redundancy to the communication function. The system should be robust that its overall function would not be influenced by partial damage, and also be flexible enough to adapt to the changes of background conditions in the future. Records and information should be preserved by way of both Relay System and Permanent System. The former would maintain record preservation and communication functions in the framework of social systems whereas the latter would consist of durable storehouse facilities, recording media and markers/monuments and be independent of any social systems and human control. Silicon carbide is one of the most promising materials for the Permanent System of Records Preservation. It is expected to be the potential candidate for long-term recording media with its superior characteristics of resistance against heat, wear and chemical impacts, and of engraving accuracy. (authors)« less

Long-term durability of HT-PEM fuel cells based on thermally cross-linked polybenzimidazole

NASA Astrophysics Data System (ADS)

Søndergaard, Tonny; Cleemann, Lars Nilausen; Becker, Hans; Aili, David; Steenberg, Thomas; Hjuler, Hans Aage; Seerup, Larisa; Li, Qingfeng; Jensen, Jens Oluf

2017-02-01

Long-term durability of high temperature polymer electrolyte membrane fuel cells based on thermally cross-linked polybenzimidazole membranes was studied and compared with reference membranes based on linear polybenzimidazole. The test was conducted at 160 °C under constant load currents of 200 mA cm-2 for periods of 1000, 4400, and 13,000 h. Extensive beginning-of-life (BoL) and end-of-test (EoT) characterisation was carried out, and disturbance of the steady state operated cells was minimised by limiting in-line diagnostics to the low-invasive technique of electrochemical impedance spectroscopy (EIS). Up until the operating time of 9200 h, the cell equipped with the cross-linked membrane showed an average degradation rate of 0.5 μV h-1, compared to 2.6 μV h-1 for the reference membrane, though parallel tests for a shorter period of time showed deviations, likely due to malfunctioning contact between layers or cell components. For the full test period of 13,000 h, the average voltage decay rate was about 1.4 and 4.6 μV h-1 for cells equipped with cross-linked and linear polybenzimidazole membranes, respectively. EIS and post-test analysis revealed that the cross-linked membrane showed better stability in terms of area specific resistance due to improved acid retention characteristics.

The Short- and Long-Term Effects of a Short Study Abroad Experience: The Case of Children

ERIC Educational Resources Information Center

Llanes, Angels

2012-01-01

This study examines to what extent L2 gains obtained during a study abroad (SA) experience are durable. Participants were 16 Catalan/Spanish bilingual children, learning English as an L2, who were distributed into two groups depending on their learning context (SA vs. at home [AH]). Participants completed a pre-test before the SA participants'…

Biological degradation of wood-plastic composites (WPC) and strategies for improving the resistance of WPC against biological decay

Treesearch

Anke Schirp; Rebecca E. Ibach; David E. Pendleton; Michael P. Wolcott

2008-01-01

Much of the research on wood-plastic composites (WPC) has focused on formulation development and processing while high biological durability of the material was assumed. The gap between assumption and knowledge in biodeterioration of WPC needs to be reduced. Although some information on the short-term resistance of WPC against biological degradation is available, long-...

The use of electrochemical impedance spectroscopy (EIS) to measure the corrosion of metals in contact with wood

Treesearch

Samuel L. Zelinka; Douglas R. Rammer

2005-01-01

Although preservative treatments prolong the life of wood, they can also contribute to the corrosion of fasteners. The corrosion of fasteners merits further study because it can affect the long-term durability of structures and fundamental knowledge of corrosion in wood is limited. The goal of this study is to determine the viability of electrochemical impedance...

Effect of water repellent preservatives and other wood treatments on restoration and durability of millwork

Treesearch

R. Sam Williams

2001-01-01

This report describes the long-term performance of painted window units that were placed outdoors near Madison, Wisconsin, in 1956. Covered in this report are the effects of the initial water repellent preservative (WRP) treatment during the first 6 years of exposure, a comparison of the water repellent effectiveness (WRE) ofthe WRP with the condition of the windows...

Group and Individual Treatment of Obsessive-Compulsive Disorder Using Cognitive Therapy and Exposure Plus Response Prevention: A 2-Year Follow-Up of Two Randomized Trials

ERIC Educational Resources Information Center

Whittal, Maureen L.; Robichaud, Melisa; Thordarson, Dana S.; McLean, Peter D.

2008-01-01

Relatively little is known about the long-term durability of group treatments for obsessive-compulsive disorder (OCD) and contemporary cognitive treatments. The current study investigated the 2-year follow-up results for participants who completed randomized trials of group or individual treatment and received either cognitive therapy (CT) or…

The Effect of Dose Rate on Composite Durability When Exposed to a Simulated Long-Term Lunar Radiation Environment

NASA Technical Reports Server (NTRS)

Rojdev, Kristina; O'Rourke, Mary Jane; Hill, Charles; Nutt, Steven; Atwell, William

2011-01-01

Human exploration of space beyond low Earth orbit (LEO) requires a safe living and working environment for crew. Composite materials are one type of material being investigated by NASA as a multi-functional structural approach to habitats for long-term use in space or on planetary surfaces with limited magnetic fields and atmosphere. These materials provide high strength with the potential for decreased weight and increased radiation protection of crew and electronics when compared with conventional aluminum structures. However, these materials have not been evaluated in a harsh radiation environment, as would be experienced outside of LEO or on a planetary surface. Thus, NASA has been investigating the durability of select composite materials in a long-term radiation environment. Previously, NASA exposed composite samples to a simulated, accelerated 30-year radiation treatment and tensile stresses similar to those of a habitat pressure vessel. The results showed evidence of potential surface oxidation and enhanced cross-linking of the matrix. As a follow-on study, we performed the same accelerated exposure alongside an exposure with a decreased dose rate. The slower dose ]rate is comparable to a realistic scenario, although still accelerated. Strain measurements were collected during exposure and showed that with a fastdose rate, the strain decreased with time, but with a slow ]dose rate, the strain increased with time. After the radiation exposures, samples were characterized via tensile tests, flexure tests, Fourier Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC). The results of these tests will be discussed.

Cumulative effect of transition metals on nitrogen and fluorine co-doped graphite nanofibers: an efficient and highly durable non-precious metal catalyst for the oxygen reduction reaction.

PubMed

Peera, S Gouse; Arunchander, A; Sahu, A K

2016-08-14

Nitrogen and fluorine co-doped graphite nanofibers (N/F-GNF) and their cumulative effect with Fe and Co have been developed as an alternative non-precious metal catalyst for efficient oxygen reduction reaction (ORR) in acidic media. The synergistic effect between the doped hetero atoms and the co-ordinated Fe and Co towards ORR activity and durability of the catalyst is deeply investigated. A high ORR onset potential comparable with commercial Pt/C catalyst is observed with the Fe-Co/NF-GNF catalyst, which indicates that this catalyst is a potential alternative to Pt/C. A fivefold increase in mass activity is achieved by the Fe-Co/NF-GNF catalyst compared to the simple N/F-GNF catalyst, which endorses the significant role of transition metal atoms in enhancing ORR activity. The advanced Fe-Co/NF-GNF catalyst also exhibits complete tolerance to CH3OH and CO. The Fe-Co/NF-GNF catalyst also exhibits excellent durability towards the ORR with only a 10 mV negative shift in its half wave potential after a 10 000 repeated potential cycling test, whereas in the case of a commercial Pt/C catalyst there was an ∼110 mV negative shift under similar environmental conditions. More stringent corrosive test cycles were also performed by maintaining the cell as high as 1.4 V with a later decrease to 0.6 V vs. RHE for 300 cycles, which showed the excellent durability of the Fe-Co/NF-GNF catalyst in comparison with the Pt/C catalyst. XPS analysis of the Fe-Co/NF-GNF catalyst presents the ORR active chemical states of N (pyridinic-N and graphitic-N) and F (semi-ionic-F) and the co-ordinated sites of Fe and Co species with the dopants. The excellent performance and durability of the Fe-Co/NF-GNF catalyst is due to the synergistic effect between the hetero atoms dopants (N and F) and strong co-ordinating bonds of M-N-C, which protect the graphene layers around the metallic species and greatly mitigates the leaching of Co and Fe during the long term cycling test. The high activity and long term durability of the Fe-Co/NF-GNF catalyst make it a promising ORR electrocatalyst for the fuel cell cathode reaction.

Does visual short-term memory have a high-capacity stage?

PubMed

Matsukura, Michi; Hollingworth, Andrew

2011-12-01

Visual short-term memory (VSTM) has long been considered a durable, limited-capacity system for the brief retention of visual information. However, a recent work by Sligte et al. (Plos One 3:e1699, 2008) reported that, relatively early after the removal of a memory array, a cue allowed participants to access a fragile, high-capacity stage of VSTM that is distinct from iconic memory. In the present study, we examined whether this stage division is warranted by attempting to corroborate the existence of an early, high-capacity form of VSTM. The results of four experiments did not support Sligte et al.'s claim, since we did not obtain evidence for VSTM retention that exceeded traditional estimates of capacity. However, performance approaching that observed in Sligte et al. can be achieved through extensive practice, providing a clear explanation for their findings. Our evidence favors the standard view of VSTM as a limited-capacity system that maintains a few object representations in a relatively durable form.

Thymidine analogue-sparing highly active antiretroviral therapy (HAART).

PubMed

Nolan, David; Mallal, Simon

2003-02-01

The use of alternative nucleoside reverse transcriptase inhibitors (NRTIs) to the thymidine analogues stavudine (d4T) and zidovudine(ZDV) has been advocated as a means of limiting long-term NRTI-associated toxicity, particularly the development of lipoatrophy or fat wasting. This approach reflects an increasing knowledge of the distinct toxicity profiles of NRTI drugs. However, recent clinical trials have demonstrated that the use of thymidine analogue NRTIs and newer alternative backbone NRTIs, such as tenofovir (TNF) and abacavir (ABC), is associated with comparable short-term efficacy and tolerability. Given the importance of toxicity profile differences in determining clinical management, it is important to recognise that d4T and ZDV cary significantly different risks for long-term NRTI toxicity. Recognising that all NRTIs, including thymidine analogues, have individual toxicity profiles provides a more appropriate basis for selecting optimal antiretroviral therapy. The safety and efficacy of TNF and ABC are also reviewed here, although the available data provide only limited knowledge of the long-term effects of these drugs in terms of toxicity and antiviral durability.

Home Start Followup Study: A Study of Long-Term Impact of Home Start on Program Participants. Executive Summary.

ERIC Educational Resources Information Center

Bache, William; Nauta, Marrit J.

This paper provides a summary of a Home Start Followup Study (HSFS) which was initiated in 1976. An attempt was made to examine the durability of gains made as the result of families' (parents and their 3- to 5-year-old children) participation in the program. In addition, the study was designed to determine whether program duration (one versus two…

Brandon Research, Inc. Orthopedic Implant Cooperative Research and Development Agreement (CRADA) Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, W.R.

1999-04-22

The project was a joint research effort between the U. S. Department of Energy's (DOE) Kansas City Plant (KCP) and Brandon Research, Inc. to develop ways to improve implants used for orthopedic surgery for joint replacement. The primary product produced by this study is design information, which may be used to develop implants that will improve long-term fixation and durability in the host bone environment.

Evolution of Force Sensing Technologies.

PubMed

Shah, Dipen

2017-06-01

In order to Improve the procedural success and long-term outcomes of catheter ablation techniques for atrial fibrillation (AF), an Important unfulfilled requirement is to create durable electrophysiologically complete lesions. Measurement of contact force (CF) between the catheter tip and the target tissue can guide physicians to optimise both mapping and ablation procedures. Contact force can affect lesion size and clinical outcomes following catheter ablation of AF. Force sensing technologies have matured since their advent several years ago, and now allow the direct measurement of CF between the catheter tip and the target myocardium in real time. In order to obtain complete durable lesions, catheter tip spatial stability and stable contact force are important. Suboptimal energy delivery, lesion density/contiguity and/or excessive wall thickness of the pulmonary vein-left atrial (PV-LA) junction may result in conduction recovery at these sites. Lesion assessment tools may help predict and localise electrical weak points resulting in conduction recovery during and after ablation. There is increasing clinical evidence to show that optimal use of CF sensing during ablation can reduce acute PV re-conduction, although prospective randomised studies are desirable to confirm long-term favourable clinical outcomes. In combination with optimised lesion assessment tools, contact force sensing technology has the potential to become the standard of care for all patients undergoing AF catheter ablation.

The operation of the century: total hip replacement.

PubMed

Learmonth, Ian D; Young, Claire; Rorabeck, Cecil

2007-10-27

In the 1960s, total hip replacement revolutionised management of elderly patients crippled with arthritis, with very good long-term results. Today, young patients present for hip-replacement surgery hoping to restore their quality of life, which typically includes physically demanding activities. Advances in bioengineering technology have driven development of hip prostheses. Both cemented and uncemented hips can provide durable fixation. Better materials and design have allowed use of large-bore bearings, which provide an increased range of motion with enhanced stability and very low wear. Minimally invasive surgery limits soft-tissue damage and facilitates accelerated discharge and rehabilitation. Short-term objectives must not compromise long-term performance. Computer-assisted surgery will contribute to reproducible and accurate placement of implants. Universal economic constraints in healthcare services dictate that further developments in total hip replacement will be governed by their cost-effectiveness.

Environmental evaluation of alternatives for long-term management of Defense high-level radioactive wastes at the Idaho Chemical Processing Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-09-01

The U.S. Department of Energy (DOE) is considering the selection of a strategy for the long-term management of the defense high-level wastes at the Idaho Chemical Processing Plant (ICPP). This report describes the environmental impacts of alternative strategies. These alternative strategies include leaving the calcine in its present form at the Idaho National Engineering Laboratory (INEL), or retrieving and modifying the calcine to a more durable waste form and disposing of it either at the INEL or in an offsite repository. This report addresses only the alternatives for a program to manage the high-level waste generated at the ICPP. 24more » figures, 60 tables.« less

Long-term benefit of PD-L1 blockade in lung cancer associated with JAK3 activation

PubMed Central

Van Allen, Eliezer M.; Golay, Hadrien G.; Liu, Yan; Koyama, Shohei; Wong, Karrie; Taylor-Weiner, Amaro; Giannakis, Marios; Harden, Maegan; Rojas-Rudilla, Vanesa; Chevalier, Aaron; Thai, Tran; Lydon, Christine; Mach, Stacy; Wong, Joshua A.; Rabin, Alexandra R.; Helmkamp, Joshua; Sholl, Lynette; Carter, Scott L.; Oxnard, Geoffrey; Janne, Pasi; Getz, Gad; Lindeman, Neal; Hammerman, Peter S.; Garraway, Levi A.; Hodi, F. Stephen; Rodig, Scott; Dranoff, Glenn; Wong, Kwok-Kin; Barbie, David A.

2015-01-01

PD-1 immune checkpoint blockade occasionally results in durable clinical responses in advanced metastatic cancers. However, mechanism-based predictors of response to this immunotherapy remain incompletely characterized. We performed comprehensive genomic profiling on a tumor and germline sample from a patient with refractory lung adenocarcinoma who achieved marked long-term clinical benefit from anti-PD-L1 therapy. We discovered activating somatic and germline amino acid variants in JAK3 that promoted PD-L1 induction in lung cancer cells and in the tumor immune microenvironment. These findings suggest that genomic alterations that deregulate cytokine receptor signal transduction could contribute to PD-L1 activation and engagement of the PD-1 immune checkpoint in lung cancer. PMID:26014096

Long-term hydrogen oxidation catalysts in alkaline fuel cells

NASA Astrophysics Data System (ADS)

Kiros, Y.; Schwartz, S.

Pt/Pd bimetallic combination and Raney Ni catalysts were employed in long-term electrochemical assessment of the hydrogen oxidation reaction (HOR) in 6 M KOH. Steady-state current vs. potential measurements of the gas diffusion electrodes have shown high activity for these types of catalysts. Durability tests of the electrodes have shown increased stability for the Pt/Pd-based catalysts than the Raney Ni at a constant load of 100 mA/cm 2 and at temperatures of 55°C and 60°C, respectively. Surface, structural and chemical analyses by BET surface area, transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were used to characterize the composite electrode/catalyst both before and after the electrochemical testing.

Understanding and managing conservation conflicts.

PubMed

Redpath, Steve M; Young, Juliette; Evely, Anna; Adams, William M; Sutherland, William J; Whitehouse, Andrew; Amar, Arjun; Lambert, Robert A; Linnell, John D C; Watt, Allan; Gutiérrez, R J

2013-02-01

Conservation conflicts are increasing and need to be managed to minimise negative impacts on biodiversity, human livelihoods, and human well-being. Here, we explore strategies and case studies that highlight the long-term, dynamic nature of conflicts and the challenges to their management. Conflict management requires parties to recognise problems as shared ones, and engage with clear goals, a transparent evidence base, and an awareness of trade-offs. We hypothesise that conservation outcomes will be less durable when conservationists assert their interests to the detriment of others. Effective conflict management and long-term conservation benefit will be enhanced by better integration of the underpinning social context with the material impacts and evaluation of the efficacy of alternative conflict management approaches. Copyright © 2012 Elsevier Ltd. All rights reserved.

Long-term tolerance to kidney allografts in a preclinical canine model.

PubMed

Kuhr, Christian S; Yunusov, Murad; Sale, George; Loretz, Carol; Storb, Rainer

2007-08-27

Durable immune tolerance supporting vascularized allotransplantation offers the possibility of extending graft survival and avoiding harmful complications of chronic immunosuppression. Immune tolerance to renal allografts was induced in a preclinical canine model through engraftment of donor hematopoietic cells using a combination of low-dose total body irradiation and a short course of immunosuppression. Subsequently, donor renal allografts were transplanted accompanied by bilateral native nephrectomies. With 5-year follow up, we found normal renal function in all recipients and no histological evidence of acute or chronic rejection. This tolerance does not extend universally to donor skin grafts, however, with two of four animals rejecting delayed donor skin grafts. Hematopoietic chimerism produces durable and robust immune tolerance to kidney allografts, although incomplete tolerance to donor skin grafting.

Advanced Oxide Material Systems For 1650 C Thermal/Environmental Barrier Coating Applications

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

2004-01-01

Advanced thermal/environmental barrier coatings (T/EBCs) are being developed for low emission SiC/SiC ceramic matrix composite (CMC) combustor and vane applications to extend the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water-vapor containing combustion environments. The 1650 C T/EBC system is required to have better thermal stability, lower thermal conductivity, and improved sintering and thermal stress resistance than current coating systems. In this paper, the thermal conductivity, water vapor stability and cyclic durability of selected candidate zirconia-/hafnia-, pyrochlore- and magnetoplumbite-based T/EBC materials are evaluated. The test results have been used to downselect the T/EBC coating materials, and help demonstrate advanced 1650OC coatings feasibility with long-term cyclic durability.

Processing and Characterization of Thousand-Hour 500 C Durable 4H-SiC JFET Integrated Circuits

NASA Technical Reports Server (NTRS)

Spry, David J.; Neudeck, Philip G.; Chen, Liangyu; Lukco, Dorothy; Chang, Carl W.; Beheim, Glenn M.; Krasowski, Michael J.; Prokop, Norman F.

2016-01-01

This work reports fabrication and testing of integrated circuits (ICs) with two levels of interconnect that consistently achieve greater than 1000 hours of stable electrical operation at 500 C in air ambient. These ICs are based on 4H-SiC junction field effect transistor (JFET) technology that integrates hafnium ohmic contacts with TaSi2 interconnects and SiO2 and Si3N4 dielectric layers over 1-m scale vertical topology. Following initial burn-in, important circuit parameters remain stable for more than 1000 hours of 500 C operational testing. These results advance the technology foundation for realizing long-term durable 500 C ICs with increased functional capability for sensing and control combustion engine, planetary, deep-well drilling, and other harsh-environment applications.

Processing and Characterization of Thousand-Hour 500 C Durable 4H-SiC JFET Integrated Circuits

NASA Technical Reports Server (NTRS)

Spry, David J.; Neudeck, Philip G.; Chen, Liang-Yu; Lukco, Dorothy; Chang, Carl W.; Beheim, Glenn M.; Krasowski, Michael J.; Prokop, Norman F.

2016-01-01

This work reports fabrication and testing of integrated circuits (ICs) with two levels of interconnect that consistently achieve greater than 1000 hours of stable electrical operation at 500 C in air ambient. These ICs are based on 4H-SiC junction field effect transistor (JFET) technology that integrates hafnium ohmic contacts with TaSi2 interconnects and SiO2 and Si3N4 dielectric layers over approximately 1-micrometer scale vertical topology. Following initial burn-in, important circuit parameters remain stable for more than 1000 hours of 500 C operational testing. These results advance the technology foundation for realizing long-term durable 500 C ICs with increased functional capability for sensing and control combustion engine, planetary, deep-well drilling, and other harsh-environment applications.

The quest for durable lesions in catheter ablation of atrial fibrillation - technological advances in radiofrequency catheters and balloon devices.

PubMed

Maurer, Tilman; Kuck, Karl-Heinz

2017-08-01

Atrial fibrillation is the most common cardiac arrhythmia and represents a growing clinical, social and economic challenge. Catheter ablation for symptomatic atrial fibrillation has evolved from an experimental procedure into a widespread therapy and offers a safe and effective treatment option. A prerequisite for durable PVI are transmural and contiguous circumferential lesions around the pulmonary veins. However, electrical reconnection of initially isolated pulmonary veins remains a primary concern and is a dominant factor for arrhythmia recurrence during long-term follow up. Areas covered: This article discusses the physiology of lesion formation using radiofrequency-, cryo- or laser- energy for pulmonary vein isolation and provides a detailed review of recent technological advancements in the field of radiofrequency catheters and balloon devices. Finally, future directions and upcoming developments for the interventional treatment of atrial fibrillation are discussed. Expert commentary: Durable conduction block across deployed myocardial lesions is mandatory not only for PVI but for any other cardiac ablation strategy as well. A major improvement urgently expected is the intraprocedural real-time distinction of durable lesions from interposed gaps with only transiently impaired electrical conduction. Furthermore, a simplification of ablation tools used for PVI is required to reduce the high technical complexity of the procedure.

Biodegradable Polymer Biolimus-Eluting Stents Versus Durable Polymer Everolimus-Eluting Stents in Patients With Coronary Artery Disease: Final 5-Year Report From the COMPARE II Trial (Abluminal Biodegradable Polymer Biolimus-Eluting Stent Versus Durable Polymer Everolimus-Eluting Stent).

PubMed

Vlachojannis, Georgios J; Smits, Pieter C; Hofma, Sjoerd H; Togni, Mario; Vázquez, Nicolás; Valdés, Mariano; Voudris, Vassilis; Slagboom, Ton; Goy, Jean-Jaques; den Heijer, Peter; van der Ent, Martin

2017-06-26

This analysis investigates the 5-year outcomes of the biodegradable polymer biolimus-eluting stent (BP-BES) and durable polymer everolimus-eluting stent (DP-EES) in an all-comers population undergoing percutaneous coronary intervention. Recent 1- and 3-year results from randomized trials have indicated similar safety and efficacy outcomes of BP-BES and DP-EES. Whether benefits of the biodegradable polymer device arise over longer follow-up is unknown. Moreover, in-depth, prospective, long-term follow-up data on metallic drug-eluting stents with durable or biodegradable polymers are scarce. The COMPARE II trial (Abluminal Biodegradable Polymer Biolimus-Eluting Stent Versus Durable Polymer Everolimus-Eluting Stent) was a prospective, randomized, multicenter, all-comers trial in which 2,707 patients were randomly allocated (2:1) to BP-BES or DP-EES. The pre-specified endpoint at 5 years was major adverse cardiac events, a composite of cardiac death, nonfatal myocardial infarction, or target vessel revascularization. Five-year follow-up was available in 2,657 patients (98%). At 5 years, major adverse cardiac events occurred in 310 patients (17.3%) in the BP-BES group and 142 patients (15.6%) in the DP-EES group (p = 0.26). The rate of the combined safety endpoint all-cause death or myocardial infarction was 15.0% in the BP-BES group versus 14.8% in the DP-EES group (p = 0.90), whereas the efficacy measure target vessel revascularization was 10.6% versus 9.0% (p = 0.18), respectively. Interestingly, definite stent thrombosis rates did not differ between groups (1.5% for BP-BES vs. 0.9% for DP-EES; p = 0.17). The 5-year analysis comparing biodegradable polymer-coated BES and the durable polymer-coated EES confirms the initial early- and mid-term results regarding similar safety and efficacy outcomes in this all-comers percutaneous coronary intervention population. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Long-term efficient organic photovoltaics based on quaternary bulk heterojunctions

NASA Astrophysics Data System (ADS)

Nam, Minwoo; Cha, Minjeong; Lee, Hyun Hwi; Hur, Kahyun; Lee, Kyu-Tae; Yoo, Jaehong; Han, Il Ki; Kwon, S. Joon; Ko, Doo-Hyun

2017-01-01

A major impediment to the commercialization of organic photovoltaics (OPVs) is attaining long-term morphological stability of the bulk heterojunction (BHJ) layer. To secure the stability while pursuing optimized performance, multi-component BHJ-based OPVs have been strategically explored. Here we demonstrate the use of quaternary BHJs (q-BHJs) composed of two conjugated polymer donors and two fullerene acceptors as a novel platform to produce high-efficiency and long-term durable OPVs. A q-BHJ OPV (q-OPV) with an experimentally optimized composition exhibits an enhanced efficiency and extended operational lifetime than does the binary reference OPV. The q-OPV would retain more than 72% of its initial efficiency (for example, 8.42-6.06%) after a 1-year operation at an elevated temperature of 65 °C. This is superior to those of the state-of-the-art BHJ-based OPVs. We attribute the enhanced stability to the significant suppression of domain growth and phase separation between the components via kinetic trapping effect.

Surgical treatment of middle aortic syndrome with Takayasu arteritis or midaortic dysplastic syndrome.

PubMed

Kim, S M; Jung, I M; Han, A; Min, S-I; Lee, T; Ha, J; Kim, S J; Min, S-K

2015-08-01

Middle aortic syndrome (MAS) is a rare condition characterized by severe stenosis of the distal thoracic or abdominal aorta. The aims of this study are to define the anatomic characteristics of MAS and to review the various surgical methods and their outcomes in terms of long-term durability Ten adult patients were diagnosed with MAS caused by Takayasu arteritis (TA) or midaortic dysplastic syndrome and underwent surgical treatment between July 1992 and January 2013. The aortic lesions were mostly suprarenal (n = 7) and stenoses were commonly found in the celiac axis (n = 6), SMA (n = 7), and renal artery (n = 6). Indications for operation were uncontrolled hypertension in six patients and lower extremity claudication in four. Eight aortic bypasses, one supraceliac aortic interposition graft, and one bilateral aorto-renal bypass were performed. Adjunctive renal bypass with saphenous vein graft (n = 4) and IMA reimplantation (n = 2) were performed simultaneously. There was no post-operative mortality, and one complication of iliac dissection at the distal anastomosis site was detected and treated by stenting. Hypertension was cured or improved in five of the six patients, and lower extremity claudication improved in all of them. With a median follow up of 60 months (range, 12-263), all the aortic bypasses were patent and one adjunctive renal artery bypass graft with aortic bypass was occluded 29 months post-operatively. Aortic bypass for MAS is safe and shows excellent long-term durability. Considering the patients are relatively young with a long life expectancy, aggressive surgical treatment could be beneficial. Lifelong follow up to monitor complications and disease progression is necessary. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Long-Term Endovascular Treatment Outcome of 46 Patients with Cavernous Sinus Dural Arteriovenous Fistulas Presenting with Ophthalmic Symptoms

PubMed Central

Pashapour, Ali; Mohammadian, Reza; Salehpour, Firooz; Sharifipour, Ehsan; Mansourizade, Reza; Mahdavifard, Ali; Salehi, Mohamadgharib; Mirzaii, Farhad; Sariaslani, Payam; Fatahzade Ardalani, Ghasem; Altafi, Davar

2014-01-01

Summary Ocular symptoms are regularly observed in patients with cavernous sinus dural arteriovenous fistulas (cDAVF). We aimed to evaluate the long-term efficacy and safety of endovascular approaches in patients with cDAVF presenting with different ocular symptoms. In a prospective study between June 2008 and March 2013, 46 patients with ocular symptoms due to cDAVF who were not eligible for conservative therapy, met the inclusion criteria and underwent endovascular treatment. They underwent a transarterial approach with histoacryl glue injections or transvenous coil embolization, all in one session. They were followed up for a mean period of 17.3 months (range 7 to 30 months) clinically and using angiography. The mean age of patients was 36.8 years (18-60) and 65% of them were male. All patients showed venous drainage into the superior and inferior orbital veins. Access to the cavernous sinus was transvenous in ten patients, transarterial in 26 patients, and mixed in ten patients. Initial symptoms were improved in 97.8% of patients and did not recur during the study follow-up. The procedural complications included: blurred vision, transient sixth nerve palsy and exacerbation of chemoproptosis in two, one and two patients respectively that completely resolved in initial weeks with no recurrence. No patient worsened or developed new symptoms suggestive of a recurrent fistula during the follow-up period. One patient experienced intracranial dissection of the internal carotid artery and ischemic stroke with an unfinished procedure. The relief of early presentation was durable in long-term follow-up and the cured lesions were stable in angiographic controls. Favorable and durable outcomes could be obtained following endovascular approaches for cDAVF presenting with different ocular symptoms. PMID:25196621

Stent Coating Integrity of Durable and Biodegradable Coated Drug Eluting Stents.

PubMed

Yazdani, Saami K; Sheehy, Alexander; Pacetti, Stephen; Rittlemeyer, Brandon; Kolodgie, Frank D; Virmani, Renu

2016-10-01

Coatings consisting of a polymer and drug are widely used in drug-eluting stents (DES) and are essential in providing programmable drug release kinetics. Among other factors, stent coating technologies can influence blood compatibility, affect acute and sub-acute healing, and potentially trigger a chronic inflammatory response. The aim of this study was to investigate the short-term (7 and 28 days) and long-term (90 and 180 days) coating integrity of the Xience Prime Everolimus-Eluting Stent (EES), Resolute Zotarolimus-Eluting Stent (ZES), Taxus Paclitaxel-Eluting Stent (PES), and Nobori Biolimus A9-Eluting Stent (BES) in a rabbit ilio-femoral stent model. Stented arteries (n = 48) were harvested and the tissue surrounding the implanted stents digested away with an enzymatic solution. Results demonstrated that the majority of struts of EES were without any coating defects with a few struts showing minor defects. Similarly, for the ZES, most of the struts were without coating defects at all time points except at 180 days. The majority of PES demonstrated mostly webbing and uneven coating. In the BES group, the majority of strut coating showed polymer cracking. Overall, the EES and ZES had fewer coating defects than the PES and BES. Coating defects, however increase over time for the ZES, whereas the percent of coating irregularities remained constant for the EES. These results provide, for the first time, a comparison of the long-term durability of these drug-eluting stent coatings in vivo. © 2016, Wiley Periodicals, Inc.

Physical-durable performance of concrete incorporating high loss on ignition-fly ash

NASA Astrophysics Data System (ADS)

Huynh, Trong-Phuoc; Ngo, Si-Huy; Hwang, Chao-Lung

2018-04-01

This study investigates the feasibility of using raw fly ash with a high loss on ignition in concrete. The fly ash-free concrete samples were prepared with different water-to-binder (w/b) ratios of 0.35, 0.40, and 0.45, whereas the fly ash concrete samples were prepared with a constant w/b of 0.40 and with various fly ash contents (10%, 20%, and 30%) as a cement substitution. The physical properties and durability performance of the concretes were evaluated through fresh concrete properties, compressive strength, strength efficiency of cement, ultrasonic pulse velocity, and resistance to sulfate attack. Test results show that the w/b ratio affected the concrete properties significantly. The incorporation of fly ash increased the workability and reduced the unit weight of fresh concrete. In addition, the fly ash concrete samples containing up to 20% fly ash exhibited an improved strength at long-term ages. Further, all of the fly ash concrete samples showed a good durability performance with ultrasonic pulse velocity value of greater than 4100 m/s and a comparable sulfate resistance to the no-fly ash concrete.

The Development of Environmental Barrier Coatings for SiCSiC Ceramic Matrix Composites: Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned CMC components to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing advanced environmental barrier coating systems, the coating integrations with next generation CMC turbine components having improved environmental stability, cyclic durability and system performance will be described. The development trends for turbine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

RECENT ADVANCES IN HIGH TEMPERATURE ELECTROLYSIS AT IDAHO NATIONAL LABORATORY: SINGLE CELL TESTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

X. Zhang; J. E. O'Brien; R. C. O'Brien

2012-07-01

An experimental investigation on the performance and durability of single solid oxide electrolysis cells (SOECs) is under way at the Idaho National Laboratory. In order to understand and mitigate the degradation issues in high temperature electrolysis, single SOECs with different configurations from several manufacturers have been evaluated for initial performance and long-term durability. A new test apparatus has been developed for single cell and small stack tests from different vendors. Single cells from Ceramatec Inc. show improved durability compared to our previous stack tests. Single cells from Materials and Systems Research Inc. (MSRI) demonstrate low degradation both in fuel cellmore » and electrolysis modes. Single cells from Saint Gobain Advanced Materials (St. Gobain) show stable performance in fuel cell mode, but rapid degradation in the electrolysis mode. Electrolyte-electrode delamination is found to have significant impact on degradation in some cases. Enhanced bonding between electrolyte and electrode and modification of the microstructure help to mitigate degradation. Polarization scans and AC impedance measurements are performed during the tests to characterize the cell performance and degradation.« less

Durability of classification and action learning: differences revealed using ex-Gaussian distribution analysis.

PubMed

Moutsopoulou, Karolina; Waszak, Florian

2013-05-01

It has been shown that in associative learning it is possible to disentangle the effects caused on behaviour by the associations between a stimulus and a classification (S-C) and the associations between a stimulus and the action performed towards it (S-A). Such evidence has been provided using ex-Gaussian distribution analysis to show that different parameters of the reaction time distribution reflect the different processes. Here, using this method, we investigate another difference between these two types of associations: What is the relative durability of these associations across time? Using a task-switching paradigm and by manipulating the lag between the point of the creation of the associations and the test phase, we show that S-A associations have stronger effects on behaviour when the lag between the two repetitions of a stimulus is short. However, classification learning affects behaviour not only in short-term lags but also (and equally so) when the lag between prime and probe is long and the same stimuli are repeatedly presented within a different classification task, demonstrating a remarkable durability of S-C associations.

Self-etching adhesives: review of adhesion to tooth structure part II.

PubMed

Strydom, C

2005-02-01

Self-etching adhesives are steadily increasing in popularity among dental practitioners with their easy handling technique and their promise of no post-op sensitivity. As with any new bonding material, in vitro and in vivo investigations are required to assess the clinical efficacy of these systems. The current literature was reviewed to provide information on these systems, including the influence of their acidity and permeability on the quality of the bond, the role of water in long-term degradation of the bond in in vivo and in vitro studies, and the clinical efficacy of the self-etching adhesives in clinical research studies. Published abstracts, reviews, laboratory reports and clinical research papers in the dental literature. Very little information is available on self-etching systems pertaining to the long-term in vitro and in vivo durability of their bond and their medium- to long-term clinical outcome. Although post-op sensitivity seems to be something of the past, short-term clinical studies show that some self-etching adhesives do not perform as well as total-etch systems.

Current indications for stentless aortic bioprostheses.

PubMed

Hegazy, Yasser Y; Rayan, Amr; Bauer, Stefan; Keshk, Noha; Bauer, Kerstin; Ennker, Ina; Ennker, Jürgen

2018-01-01

The best aortic prostheses have been debated for decades. The introduction of stentless aortic bioprostheses was aimed at improving hemodynamics and potentially the durability of aortic bioprostheses. Despite the good short- and long-term outcomes after implantation of stentless aortic bioprostheses, their use remains limited owing to the technically demanding implantation techniques. Nevertheless, stentless aortic bioprostheses might be of special benefit in certain indications, where they could be a valuable addition to the surgical armamentarium.

Laboratory Evaluation of Expedient Low-Temperature Concrete Admixtures for Repairing Blast Holes in Cold Weather

DTIC Science & Technology

2013-01-08

This re- search ignores effects on long-term durability, trafficability, temperature rebar corrosion , and other concerns that are of minimal... concrete because it can cause corrosion of steel reinforcement. However, the corrosion problem develops slowly with time; therefore, this problem has a...ER D C/ CR RE L TR -1 3- 1 Laboratory Evaluation of Expedient Low- Temperature Concrete Admixtures for Repairing Blast Holes in Cold

High-temperature durability considerations for HSCT combustor

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

1992-01-01

The novel combustor designs for the High Speed Civil Transport will require high temperature materials with long term environmental stability. Higher liner temperatures than in conventional combustors and the need for reduced weight necessitates the use of advanced ceramic matrix composites. The combustor environment is defined at the current state of design, the major degradation routes are discussed for each candidate ceramic material, and where possible, the maximum use temperatures are defined for these candidate ceramics.

Laboratory Evaluation of Expedient Low-Temperature Admixtures for Runway Craters in Cold Weather

DTIC Science & Technology

2014-10-01

ignores typical concerns, such as long-term durability, aesthetics, and corrosion , that are of minimal importance in this expedient field- use ...those identified to be in common use although it was acknowledged that the chloride based compounds caused corrosion problems (Korhonen 1990...batch to batch when using less than a 2000 lb batch, our ability to model and predict results with each batch is degraded. How- ever, when we control

Long-Term Viscoelastic Response of E-glass/Bismaleimide Composite in Seawater Environment

NASA Astrophysics Data System (ADS)

Yian, Zhao; Zhiying, Wang; Keey, Seah Leong; Boay, Chai Gin

2015-12-01

The effect of seawater absorption on the long-term viscoelastic response of E-glass/BMI composite is presented in this paper. The diffusion of seawater into the composite shows a two-stage behavior, dominated by Fickian diffusion initially and followed by polymeric relaxation. The Glass transition temperature (Tg) of the composite with seawater absorption is considerably lowered due to the plasticization effect. However the effect of water absorption at 50 °C is found to be reversible after drying process. The time-temperature superposition (TTS) was performed based on the results of Dynamic Mechanical Analysis to construct the master curve of storage modulus. The shift factors exhibit Arrhenius behavior when temperature is well below Tg and Vogel-Fulcher-Tammann (VFT) like behavior when temperature gets close to glass transition region. As a result, a semi-empirical formulation is proposed to account for the seawater absorption effect in predicting long-term viscoelastic response of BMI composites based on temperature dependent storage modulus and TTS. The predicted master curves show that the degradation of storage modulus accelerates with both seawater exposure and increasing temperature. The proposed formulation can be applied to predict the long-term durability of any thermorheologically simple composite materials in seawater environment.

Short-term and long-term attentional biases to frequently encountered target features.

PubMed

Sha, Li Z; Remington, Roger W; Jiang, Yuhong V

2017-07-01

It has long been known that frequently occurring targets are attended better than infrequent ones in visual search. But does this frequency-based attentional prioritization reflect momentary or durable changes in attention? Here we observed both short-term and long-term attentional biases for visual features as a function of different types of statistical associations between the targets, distractors, and features. Participants searched for a target, a line oriented horizontally or vertically among diagonal distractors, and reported its length. In one set of experiments we manipulated the target's color probability: Targets were more often in Color 1 than in Color 2. The distractors were in other colors. Participants found Color 1 targets more quickly than Color 2 targets, but this preference disappeared immediately when the target's color became random in the subsequent testing phase. In the other set of experiments, we manipulated the diagnostic values of the two colors: Color 1 was more often a target than a distractor; Color 2 was more often a distractor than a target. Participants found Color 1 targets more quickly than Color 2 targets. Importantly, and in contrast to the first set of experiments, the featural preference was sustained in the testing phase. These results suggest that short-term and long-term attentional biases are products of different statistical information. Finding a target momentarily activates its features, inducing short-term repetition priming. Long-term changes in attention, on the other hand, may rely on learning diagnostic features of the targets.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christians, Jeffrey A.; Schulz, Philip; Tinkham, Jonathan S.

Long-term device stability is the most pressing issue that impedes perovskite solar cell commercialization, given the achieved 22.7% efficiency. The perovskite absorber material itself has been heavily scrutinized for being prone to degradation by water, oxygen and ultraviolet light. To date, most reports characterize device stability in the absence of these extrinsic factors. Here we show that, even under the combined stresses of light (including ultraviolet light), oxygen and moisture, perovskite solar cells can retain 94% of peak efficiency despite 1,000 hours of continuous unencapsulated operation in ambient air conditions (relative humidity of 10-20%). Each interface and contact layer throughoutmore » the device stack plays an important role in the overall stability which, when appropriately modified, yields devices in which both the initial rapid decay (often termed burn-in) and the gradual slower decay are suppressed. This extensively modified device architecture and the understanding developed will lead towards durable long-term device performance.« less

Long-term outcome in dogs undergoing mitral valve repair with suture annuloplasty and chordae tendinae replacement.

PubMed

Mizuno, T; Mizukoshi, T; Uechi, M

2013-02-01

Mitral valve repair under cardiopulmonary bypass was performed in three dogs with clinical signs associated with mitral regurgitation that were not controlled by medication. Mitral valve repair comprised circumferential annuloplasty and chordal replacement with expanded polytetrafluoroethylene. One dog died 2 years after surgery because of severe mitral regurgitation resulting from partial circumferential suture detachment. The others survived for over 5 years, but mild mitral valve stenosis persisted in one. The replaced chordae did not rupture in any dog. Mitral valve repair appears to be an effective treatment for mitral regurgitation in dogs. Chordal replacement with expanded polytetrafluoroethylene is a feasible technique, demonstrating long-term durability in dogs. However, mitral annuloplasty techniques need improvement. © 2012 British Small Animal Veterinary Association.

A 76-year old man with a torn Freedom SOLO bioprosthesis.

PubMed

Wollersheim, Laurens W; Li, Wilson W; van der Meulen, Jan; de Mol, Bas A

2014-01-01

We describe a case of a 76-year old male who presented with progressive dyspnoea. He underwent an aortic valve replacement with a Freedom SOLO bioprosthesis 6 years ago. Transthoracic echocardiography showed a moderate-to-severe leakage of the Freedom SOLO bioprosthesis. During surgical reintervention, a partial tear of the left coronary cusp was seen from the commissure of the right coronary cusp to its base. After radiographic and microscopic examination, no clear cause was found for the failure of this Freedom SOLO bioprosthesis. To our knowledge, this is the third failure of a Freedom SOLO bioprosthesis reported in the literature. When the long-term follow-up of the Freedom SOLO bioprosthesis is available, it has to be compared with other bioprosthesis for long-term durability.

System considerations favoring rotary artificial hearts with blood-immersed bearings.

PubMed

Jarvik, R K

1995-07-01

Hydrodynamic blood pumps provide such advantages as not requiring an air vent or compliance chamber as well as a great reduction in mechanical complexity with the potential for very long durability. The detailed design of their bearings is emerging as the single most important determinant of long-term success. Three categories of bearings include remote force, such as magnetic suspension; blood-isolated, which require a shaft seal; and blood-immersed using either mechanical or hydrodynamic support. Blood-immersed bearings permit maximum simplification and miniaturization of the entire system, require no flush fluid, and require no electronics as with magnetic suspension. The Jarvik 2000 heart represents an example of their potential. The intraventricular titanium pump (25 mm diameter, 25 cc, 85 g), uses blood flow through the motor air gap with blood-immersed bearings. The longest in vitro bearing durability test is ongoing at 20,000,000,000 revolutions with minimal wear (3 years at 15,000 rpm). In vivo results include 5-month calf survival, no thromboembolism, plasma Hb 2-5 mg%, and power under 10 W.

Sustainable and long-time 'rejuvenation' of biomimetic water-repellent silica coating on polyester fabrics induced by rough mechanical abrasion.

PubMed

Rosu, Cornelia; Lin, Haisheng; Jiang, Lu; Breedveld, Victor; Hess, Dennis W

2018-04-15

The economical use of water-repellent coatings on polymeric materials in commercial and industrial applications is limited by their mechanical wear robustness and long-term durability. In this study, we demonstrate that polyethylene terephthalate (PET) fabric modified with inorganic, methyltrimethoxysilane (MTMS)-based coatings shows excellent resistance against various types of wear damage, thereby mimicking superhydrophobic biological materials. These features were facilitated by the rational design of coating processing that also enabled tunable hierarchical surface structure. A series of custom and standard testing protocols revealed that coating-to-substrate adhesion was remarkably high, as was the resistance to various mechanical abradents. The most intriguing characteristic observed during aging and abrasion cycles was the enhancement in non-wettability or 'rejuvenation' reflected by water droplet roll-off behavior, a characteristic of self-cleaning materials. Water-repellent properties of coated polyester were also enhanced by prolonged thermal annealing and were maintained after custom laundry. The developed technology offers opportunities to design low cost, durable and functional textiles for both indoor and outdoor applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Bio-artificial pleura using an autologous dermal fibroblast sheet

NASA Astrophysics Data System (ADS)

Kanzaki, Masato; Takagi, Ryo; Washio, Kaoru; Kokubo, Mami; Yamato, Masayuki

2017-10-01

Air leaks (ALs) are observed after pulmonary resections, and without proper treatment, can produce severe complications. AL prevention is a critical objective for managing patients after pulmonary resection. This study applied autologous dermal fibroblast sheets (DFS) to close ALs. For sealing ALs in a 44-year-old male human patient with multiple bullae, a 5 × 15-mm section of skin was surgically excised. From this skin specimen, primary dermal fibroblasts were isolated and cultured for 4 weeks to produce DFSs that were harvested after a 10-day culture. ALs were completely sealed using surgical placement of these autologous DFSs. DFS were found to be a durable long-term AL sealant, exhibiting requisite flexibility, elasticity, durability, biocompatibility, and usability, resulting reliable AL closure. DFS should prove to be an extremely useful tissue-engineered pleura substitute.

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.

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.

Erection capability is potentiated by long-term sildenafil treatment: role of blood flow-induced endothelial nitric-oxide synthase phosphorylation.

PubMed

Musicki, Biljana; Champion, Hunter C; Becker, Robyn E; Liu, Tongyun; Kramer, Melissa F; Burnett, Arthur L

2005-07-01

Despite demonstrated clinical efficacy of sildenafil for the temporary treatment of erectile dysfunction, the possibility that sildenafil used long-term durably augments erectile ability remains unclear. We investigated whether continuous long-term administration of sildenafil at clinically relevant levels to aged rats "primes" the penis for improved erectile ability and involves nitric oxide (NO) or RhoA/Rho-kinase signaling pathways. In aged, but not young rats, sildenafil prolonged erection and increased the protein expressions of phosphorylated endothelial NO synthase (eNOS) at serine-1177 and phosphorylated Akt at serine-473 in penes. Only in the young rat penis, protein expressions of phosphodiesterase-5 and phosphomyosin phosphatase target subunit 1, a marker of Rho-kinase activity, were increased by sildenafil. Sildenafil inhibited phosphodiesterase-5 activity in penes of young and aged rats coincident with assayed free plasma levels of the drug equivalent to clinically therapeutic measurements. We conclude that erectile ability can be enhanced under preconditions of erectile impairment by long-term inhibition of phosphodiesterase-5 and that the effect is mediated by Akt-dependent eNOS phosphorylation. The lack of erectile ability enhancement in young rats by long-term phosphodiesterase-5 inhibition may relate to restrained NO signaling by phosphodiesterase-5 up-regulation, lack of incremental Akt and eNOS phosphorylation, and heightened Rho-kinase signaling in the penis.

Durability of high performance concrete in magnesium brine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumidajski, P.J.; Chan, G.W.

1996-04-01

The durability of six concretes exposed to magnesium brine was monitored for 24 months. These concretes incorporated ground granulated blast furnace slag, silica fume, and fly ash. The Young`s moduli, chloride penetrations, and median pore diameters were measured. There was a cyclic nature to these properties due to the complicated interaction of hydration with magnesium, chloride and sulfate attack. Mineral admixtures, in combination with a long initial cure, provided the most durable concrete. Concrete with 65% slag had the best overall durability to the brines tested.

Depth of Processing and Age Differences.

PubMed

Kheirzadeh, Shiela; Pakzadian, Sarah Sadat

2016-10-01

The present article is aimed to investigate whether there are any differences between youngsters and adults in their working and long-term memory functioning. The theory of Depth of Processing (Craik and Lockhart in J Verbal Learning Verbal Behav 11:671-684, 1972) discusses the varying degrees of strengths of memory traces as the result of differential levels of processing on the retrieved input. Additionally, they claim that there are three levels of visual, auditory and semantic processes applied on the stimuli in the short-term memory leading to discrepancy in the durability of the memory traces and the later ease of recall and retrieval. In the present article, it is tried to demonstrate if there are evidences of more durable memory traces formed after semantic, visual and auditory processions of the incoming language data in two groups of (a) children in their language learning critical age and (b) youngsters who have passed the critical age period. The comparisons of the results made using two-way ANOVAs revealed the superiority of semantic processing for both age groups in recall, retention and consequently recognition of the new English vocabularies by EFL learners.

Long-Term Durability and Integrity of Built-In Piezoelectric-Based Active Sensing Network in Structures

DTIC Science & Technology

2007-03-31

iterating to the end-time step. 1.3 Code Verification 1.3.1 Statement of the Problem A square aluminum alloy plate (thickness = 1.02 mm, width and...plate. The electro-mechanical properties of the piezoelectric materials (APC850) are available from American Piezoceramics, Inc. . The piezoceramic...structural usage and provide an early indication of physical damage. Piezoelectric (PZT) based SHM systems are among the most widely used for active and

A magnetic fluid seal for rotary blood pumps: effects of seal structure on long-term performance in liquid.

PubMed

Mitamura, Yoshinori; Takahashi, Sayaka; Amari, Shuichi; Okamoto, Eiji; Murabayashi, Shun; Nishimura, Ikuya

2011-03-01

A magnetic fluid (MF) seal enables mechanical contact-free rotation of the shaft and hence has excellent durability. The performance of an MF seal, however, has been reported to decrease in liquids. We developed an MF seal that has a "shield" mechanism, and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. Three types of MF seals were used. Seal A was a conventional seal without a shield. Seal B had the same structure as that of Seal A, but the seal was installed at 1 mm below liquid level. Seal C was a seal with a shield and the MF was set at 1 mm below liquid level. Seal A failed after 6 and 11 days. Seal B showed better results (20 and 73 days). Seal C showed long-term durability (217 and 275 days). The reason for different results in different seal structures was considered to be different flow conditions near the magnetic fluid. Fluid dynamics near the MF in the pump were analyzed using computational fluid dynamics (CFD) software. We have developed an MF seal with a shield that works in liquid for >275 days. The MF seal is promising as a shaft seal for rotary blood pumps.

Fibre Concrete 2017

NASA Astrophysics Data System (ADS)

2017-09-01

9th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance concretes (UHPC) Preface The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance concretes regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering. The 9th International Conference Fibre Concrete 2017 had 109 participants from 27 countries all over the world. 55 papers were presented including keynote lectures of Professor Bažant, Professor Bartoš and Dr. Broukalová. The conference program covered wide range of topics from scientific research to practical applications. The presented contributions related to performance and behaviour of cement based composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications. This conference was organized also to honour Professor Zděnek P. Bažant on the occasion of his jubilee and to appreciate his merits and discoveries in the field of fibre reinforced composites, structural mechanics and engineering.

Four decades of experience with mitral valve repair: analysis of differential indications, technical evolution, and long-term outcome.

PubMed

DiBardino, Daniel J; ElBardissi, Andrew W; McClure, R Scott; Razo-Vasquez, Ozwaldo A; Kelly, Nicole E; Cohn, Lawrence H

2010-01-01

To determine the long-term outcomes of mitral valvuloplasty for myxomatous valve disease, rheumatic valve disease, and functional mitral regurgitation. A total of 1503 patients underwent mitral valvuloplasty by a single surgeon between February 1972 and April 2008 and were retrospectively reviewed for short- and long-term results. Overall mean age was 60.3 + or - 13.7 years, and 57% were male. The cause was rheumatic in 193 patients, myxomatous in 1042 patients, and ischemic and nonischemic functional mitral regurgitation in 236 patients. Ring annuloplasty was performed in 1306 patients (87%). Commissurotomy was the primary repair for rheumatic valves, posterior leaflet resection and reconstruction was the most common repair for myxomatous valves (527/1042 [51%]), and ring reduction annuloplasty was the primary operation for functional mitral regurgitation. The 30-day mortality was 19 of 1503 patients (1.3%) and significantly higher in the functional mitral regurgitation group (11/236 patients, 4.7% vs 0.5% in the rheumatic group and 0.6% in the myxomatous group, P < .01). The 10-, 20-, and 30-year survivals were similar for the rheumatic and myxomatous groups (77%, 56%, and 39% vs 79%, 62%, and 52%, respectively) but significantly less for the functional mitral regurgitation group (44%, 4%, and 0%, respectively, log-rank P < .0001). The 10- and 20-year freedom from reoperation rates were significantly better for the myxomatous group than for the rheumatic group (90% and 82% vs 66% and 34%, log-rank P < .0001), with a 30-year freedom from reoperation of only 10% for rheumatic repair. In the myxomatous group, freedom from reoperation was lower in patients with anterior leaflet pathology (P = .0008). Follow-up data to 36 years demonstrate that cause strongly determines survival and durability of mitral valvuloplasty; patients with rheumatic valve disease who survive more than 20 years require reoperation, whereas functional mitral regurgitation carries the highest short- and long-term mortality rates and lowest freedom from reoperation. Mitral valvuloplasty for myxomatous valves demonstrates the longest durability, with many patients free from reoperation at 30 years. Copyright 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Assessment of structural valve deterioration of transcatheter aortic bioprosthetic balloon-expandable valves using the new European consensus definition.

PubMed

Eltchaninoff, Hélène; Durand, Eric; Avinée, Guillaume; Tron, Christophe; Litzler, Pierre-Yves; Bauer, Fabrice; Dacher, Jean-Nicolas; Werhlin, Camille; Bouhzam, Najime; Bettinger, Nicolas; Candolfi, Pascal; Cribier, Alain

2018-03-30

Durability of transcatheter aortic bioprosthetic valves remains a major issue. Standardised definitions of deterioration and failure of bioprosthetic valves have recently been proposed. The aim of this study was to assess structural transcatheter valve deterioration (SVD) and bioprosthetic valve failure (BVF) using these new definitions. All TAVI patients implanted up to September 2012 with a minimal theoretical five-year follow-up were included. Systematic clinical and echocardiographic follow-up was performed annually. New standardised definitions were used to assess durability of transcatheter aortic bioprosthetic valves. From 2002 to 2012, 378 patients were included. Mean age and logistic EuroSCORE were 83.3±6.8 years and 22.8±13.1%. Thirty-day mortality was 13.2%. Nine patients had SVD including two severe forms and two patients had definite late BVF. The incidence of SVD and BVF at eight years was 3.2% (95% CI: 1.45-6.11) and 0.58% (95% CI: 0.15-2.75), respectively. Even though limited by the poor survival of the very high-risk/compassionate early population, our data do not demonstrate any alarm concerning transcatheter aortic valve durability. Careful prospective assessment in younger and lower-risk patients and comparison with surgical bioprosthetic valves are required for further assessment of the long-term durability of transcatheter valves.

Durability-Based Design Criteria for a Quasi-Isotropic Carbon-Fiber-Reinforced Thermoplastic Automotive Composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naus, Dan J; Corum, James; Klett, Lynn B

2006-04-01

This report provides recommended durability-based design properties and criteria for a quais-isotropic carbon-fiber thermoplastic composite for possible automotive structural applications. The composite consisted of a PolyPhenylene Sulfide (PPS) thermoplastic matrix (Fortron's PPS - Ticona 0214B1 powder) reinforced with 16 plies of carbon-fiber unidirectional tape, [0?/90?/+45?/-45?]2S. The carbon fiber was Hexcel AS-4C and was present in a fiber volume of 53% (60%, by weight). The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Freedom Car and Vehicle Technologies and is closely coordinated with the Advanced Composites Consortium, is to develop durability-driven design datamore » and criteria to assure the long-term integrity of carbon-fiber-based composite systems for automotive structural applications. This document is in two parts. Part 1 provides design data and correlations, while Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects of short-time, cyclic, and sustained loadings; temperature; fluid environments; and low-energy impacts (e.g., tool drops and kickups of roadway debris) on deformation, strength, and stiffness. Guidance for design analysis, time-independent and time-dependent allowable stresses, rules for cyclic loadings, and damage-tolerance design guidance are provided.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linard, Joshua; Hall, Steve

9.1 Compliance Summary The Lakeview, Oregon, Uranium Mill Tailings Radiation Control Act (UMTRCA) Title I Disposal Site was inspected September 16 and 17, 2015. Other than some ongoing concern with erosion-control rock riprap degradation, the disposal cell was in good condition. Some minor fence repairs and vegetation removal, and minor erosion repair work along the west site fence is planned. Inspectors identified no other maintenance needs or cause for a follow-up or contingency inspection. Disposal cell riprap is evaluated annually to ensure continued long-term protection of the cell from erosion during a severe precipitation event. Degradation of the rock riprapmore » was first observed at the site in the mid-1990s. Rock gradation monitoring of the riprap on the west side slope has been performed as part of the annual inspection since 1997 to determine the mean diameter (D 50) value. As prescribed by the monitoring procedure, the rock monitoring is routinely conducted at random locations. However, at the U.S. Nuclear Regulatory Commission’s (NRC’s) request, the 2015 rock monitoring approach deviated from the normal procedure by using a pre-established monitoring grid in a subset area of the west side slope. This changed the monitoring approach from random sampling to biased sampling. The D 50 value measured during the 2015 gradation monitoring is 2.39 inches, which falls below the original D 50 design size range of 2.7–3.9 inches for the Type B size side slope riprap. At NRC’s request, rock durability monitoring was added to the gradation monitoring in 2009 to monitor durability by rock type. Results of the 2015 durability monitoring showed that74 percent of the total rock sampled is durability class code A rock with an assigned durability class of “highly durable” or durability class code B “durable” rock, and that over 90 percent of the 3-inch or larger rock is durability class code A or B. The rock durability classifications are further explained in Section 9.4.2.2.« less

Nuclear waste forms for actinides

PubMed Central

Ewing, Rodney C.

1999-01-01

The disposition of actinides, most recently 239Pu from dismantled nuclear weapons, requires effective containment of waste generated by the nuclear fuel cycle. Because actinides (e.g., 239Pu and 237Np) are long-lived, they have a major impact on risk assessments of geologic repositories. Thus, demonstrable, long-term chemical and mechanical durability are essential properties of waste forms for the immobilization of actinides. Mineralogic and geologic studies provide excellent candidate phases for immobilization and a unique database that cannot be duplicated by a purely materials science approach. The “mineralogic approach” is illustrated by a discussion of zircon as a phase for the immobilization of excess weapons plutonium. PMID:10097054

Determination of atomic oxygen fluence using spectrophotometric analysis of infrared transparent witness coupons for long duration exposure tests

NASA Technical Reports Server (NTRS)

Podojil, Gregg M.; Jaworske, Donald A.

1993-01-01

Atomic oxygen degradation is one of several major threats to the durability of spaceborne systems in low Earth orbit. Ground-based simulations are conducted to learn how to minimize the adverse effects of atomic oxygen exposure. Assessing the fluence of atomic oxygen in test chambers such as a plasma asher over long periods of time is necessary for accurate determination of atomic oxygen exposure. Currently, an atomic oxygen susceptible organic material such as Kapton is placed next to samples as a witness coupon and its mass loss is monitored and used to determine the effective atomic oxygen fluence. However, degradation of the Kapton witness coupons occurs so rapidly in plasma ashers that for any long term test many witness coupons must be used sequentially in order to keep track of the fluence. This necessitates opening vacuum to substitute fresh coupons. A passive dosimetry technique was sought to monitor atomic oxygen exposure over longer periods without the need to open the plasma asher to the atmosphere. This paper investigates the use of spectrophotometric analysis of durable IR transparent witness coupons to measure atomic oxygen exposure for longer duration testing. The method considered would be conductive to making in situ measurements of atomic oxygen fluence.

Habitats and Surface Construction Technology and Development Roadmap

NASA Technical Reports Server (NTRS)

Cohen, Marc; Kennedy, Kriss J.

1997-01-01

The vision of the technology and development teams at NASA Ames and Johnson Research Centers is to provide the capability for automated delivery and emplacement of habitats and surface facilities. The benefits of the program are as follows: Composites and Inflatables: 30-50% (goal) lighter than Al Hard Structures; Capability for Increased Habitable Volume, Launch Efficiency; Long Term Growth Potential; and Supports initiation of commercial and industrial expansion. Key Habitats and Surface Construction (H&SC) technology issues are: Habitat Shell Structural Materials; Seals and Mechanisms; Construction and Assembly: Automated Pro-Deploy Construction Systems; ISRU Soil/Construction Equipment: Lightweight and Lower Power Needs; Radiation Protection (Health and Human Performance Tech.); Life Support System (Regenerative Life Support System Tech.); Human Physiology of Long Duration Space Flight (Health and Human Performance Tech.); and Human Psychology of Long Duration Space Flight (Health and Human Performance Tech.) What is being done regarding these issues?: Use of composite materials for X-38 CRV, RLV, etc.; TransHAB inflatable habitat design/development; Japanese corporations working on ISRU-derived construction processes. What needs to be done for the 2004 Go Decision?: Characterize Mars Environmental Conditions: Civil Engineering, Material Durability, etc.; Determine Credibility of Inflatable Structures for Human Habitation; and Determine Seal Technology for Mechanisms and Hatches, Life Cycle, and Durability. An overview encompassing all of the issues above is presented.

Brush Seal Performance and Durability Issues Based on T-700 Engine Test Results

NASA Technical Reports Server (NTRS)

Hendricks, R. C.

1994-01-01

The integrity and performance of brush seals have been established. Severe bench and engine tests have shown high initial wear or run-in rates, material smearing at the interface, and bristle and rub-runner wear, but the brush seals did not fail. Short-duration (46 hr) experimental T-700 engine testing of the compressor discharge seal established over 1-percent engine performance gain (brush versus labyrinth). Long-term gains were established only as leakage comparisons, with the brush at least 20 percent better at controlling leakage. Long-term materials issues, such as wear and ultimately seal life, remain to be resolved. Future needs are cited for materials and analysis tools that account for heat generation, thermomechanical behavior, and tribological pairing to enable original equipment manufacturers to design high-temperature, high-surface-speed seals with confidence.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Won, Jong-Pil, E-mail: jpwon@konkuk.ac.kr; Hwang, Un-Jong; Lee, Su-Jin

This study evaluated the performance of shotcrete using high strength C{sub 12}A{sub 7} mineral-based accelerator that has been developed to improve the durability and long-term strength. Rebound, compressive strength and flexural strength were tested in the field. Test result showed that existing C{sub 12}A{sub 7} mineral-based accelerator exhibits better early strength than the high-strength C{sub 12}A{sub 7} mineral-based accelerator until the early age, but high-strength C{sub 12}A{sub 7} mineral-based accelerator shows about 29% higher at the long-term age of 28 days. Microstructural analysis such as scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption method was evaluated to analyzemore » long-term strength development mechanism of high strength C{sub 12}A{sub 7} mineral-based accelerator. As analysis result, it had more dense structure due to the reaction product by adding material that used to enhanced strength. It had better resistance performance in chloride ion penetration, freezing–thawing and carbonation than shotcrete that used existing C{sub 12}A{sub 7} mineral-based accelerator.« less

Amorphous Nickel-Cobalt-Borate Nanosheet Arrays for Efficient and Durable Water Oxidation Electrocatalysis under Near-Neutral Conditions.

PubMed

Chen, Lanlan; Ren, Xiang; Teng, Wanqing; Shi, Pengfei

2017-07-21

Electrolytic hydrogen generation needs earth-abundant oxygen evolution reaction electrocatalysts that perform efficiently at mild pH. Here, the development of amorphous nickel-cobalt-borate nanosheet arrays on macroporous nickel foam (NiCo-Bi/NF) as a 3D catalyst electrode for high-performance water oxidation in near-neutral media is reported. To drive a current density of 10 mA cm -2 , the resulting NiCo-Bi/NF demands an overpotential of only 430 mV in 0.1 m potassium borate (K-Bi, pH 9.2). Moreover, it also shows long-term electrochemical durability with maintenance of catalytic activity for 20 h, achieving a high turnover frequency of 0.21 s -1 at an overpotential of 550 mV. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combining regenerative medicine strategies to provide durable reconstructive options: auricular cartilage tissue engineering.

PubMed

Jessop, Zita M; Javed, Muhammad; Otto, Iris A; Combellack, Emman J; Morgan, Siân; Breugem, Corstiaan C; Archer, Charles W; Khan, Ilyas M; Lineaweaver, William C; Kon, Moshe; Malda, Jos; Whitaker, Iain S

2016-01-28

Recent advances in regenerative medicine place us in a unique position to improve the quality of engineered tissue. We use auricular cartilage as an exemplar to illustrate how the use of tissue-specific adult stem cells, assembly through additive manufacturing and improved understanding of postnatal tissue maturation will allow us to more accurately replicate native tissue anisotropy. This review highlights the limitations of autologous auricular reconstruction, including donor site morbidity, technical considerations and long-term complications. Current tissue-engineered auricular constructs implanted into immune-competent animal models have been observed to undergo inflammation, fibrosis, foreign body reaction, calcification and degradation. Combining biomimetic regenerative medicine strategies will allow us to improve tissue-engineered auricular cartilage with respect to biochemical composition and functionality, as well as microstructural organization and overall shape. Creating functional and durable tissue has the potential to shift the paradigm in reconstructive surgery by obviating the need for donor sites.

Studies on the corrosion resistance of reinforced steel in concrete with ground granulated blast-furnace slag--An overview.

PubMed

Song, Ha-Won; Saraswathy, Velu

2006-11-16

The partial replacement of clinker, the main constituent of ordinary Portland cement by pozzolanic or latent hydraulic industrial by-products such as ground granulated blast furnace slag (GGBFS), effectively lowers the cost of cement by saving energy in the production process. It also reduces CO2 emissions from the cement plant and offers a low priced solution to the environmental problem of depositing industrial wastes. The utilization of GGBFS as partial replacement of Portland cement takes advantage of economic, technical and environmental benefits of this material. Recently offshore, coastal and marine concrete structures were constructed using GGBFS concrete because high volume of GGBFS can contribute to the reduction of chloride ingress. In this paper, the influence of using GGBFS in reinforced concrete structures from the durability aspects such as chloride ingress and corrosion resistance, long term durability, microstructure and porosity of GGBFS concrete has been reviewed and discussed.

Ethanol-diesel fuel blends -- a review.

PubMed

Hansen, Alan C; Zhang, Qin; Lyne, Peter W L

2005-02-01

Ethanol is an attractive alternative fuel because it is a renewable bio-based resource and it is oxygenated, thereby providing the potential to reduce particulate emissions in compression-ignition engines. In this review the properties and specifications of ethanol blended with diesel fuel are discussed. Special emphasis is placed on the factors critical to the potential commercial use of these blends. These factors include blend properties such as stability, viscosity and lubricity, safety and materials compatibility. The effect of the fuel on engine performance, durability and emissions is also considered. The formulation of additives to correct certain key properties and maintain blend stability is suggested as a critical factor in ensuring fuel compatibility with engines. However, maintaining vehicle safety with these blends may entail fuel tank modifications. Further work is required in specifying acceptable fuel characteristics, confirming the long-term effects on engine durability, and ensuring safety in handling and storing ethanol-diesel blends.

New immiscible refrigeration lubricant for HFCs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sunami, Motoshi; Takigawa, Katsuya; Suda, Satoshi

1995-12-31

This study examines the capability of a family of very low-viscosity alkylbenzenes (AB) used in high-side rotary compressors for HFCs. In the development of refrigeration lubricants for HFCs, miscibility is one of the most important problems to be solved. Therefore, PAG (polyalkylene glycols) and POE (polyol esters), which have good miscibility, have been applied in new HFC applications. However, it is difficult for these lubricants to maintain long-term durability in high-side rotary compressors. In friction tests under high HFC pressure, ABs with much lower viscosities than mineral oil maintained a much stronger oil film than the combination of mineral oil/R-12more » or POE/HFCs. These results were also proven by compressor durability tests. From the study of the solubility of ABs and HFCs, it is suggested that the total amount of refrigerant can be reduced because HFCs are barely soluble with ABs inside the high-side shell.« less

Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

2009-01-01

Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

Meta-analysis using individual patient data: efficacy and durability of topical alicaforsen for the treatment of active ulcerative colitis.

PubMed

Vegter, S; Tolley, K; Wilson Waterworth, T; Jones, H; Jones, S; Jewell, D

2013-08-01

The antisense ICAM-1 inhibitor alicaforsen has been studied in four phase 2 studies in ulcerative colitis (UC). Recruited patients varied as to the extent of their colitis and in the severity of disease at entry. To investigate the efficacy of alicaforsen enema in specific UC populations. Efficacy was analysed for short-term (week 6-10) and long-term (week 30) outcomes compared with either placebo or a high-dose mesalazine (mesalamine) enema in patients with disease extent up to 40 cm from the anal verge in patients with moderate or severe disease, and in patients with both of these features. Individual patient data meta-analyses of 200 patients from four phase 2 studies evaluating nightly alicaforsen 240 mg enema and comparators. Patient data were pooled and analysed in a single data set. Continuous outcomes were evaluated using anova; dichotomous outcomes were evaluated using Pearson chi-square or Fisher's exact tests. Alicaforsen showed superior efficacy vs. placebo in: patients with disease extent up to 40 cm, patients with moderate and severe disease and especially when both those conditions were satisfied. In these patient groups, mesalazine also showed short-term efficacy. At week 30, however, the efficacy of mesalazine waned and alicaforsen became significantly more efficacious. This post hoc meta-analysis showed that alicaforsen is effective in patients with active UC, especially in patients with distal disease, which is of moderate/severe activity. The efficacy of alicaforsen was durable in these sub-groups, suggesting a disease-modifying effect. This analysis suggests that alicaforsen enema may offer an effective, potentially durable response in moderate/severe distal active UC. © 2013 John Wiley & Sons Ltd.

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

USGS Publications Warehouse

Klich, I.; Wilding, L.P.; Drees, L.R.; Landa, E.R.

1999-01-01

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or archived in a laboratory, warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.

Accelerated Weathering of Waste Glass at 90°C with the Pressurized Unsaturated Flow (PUF) Apparatus: Implications for Predicting Glass Corrosion with a Reactive Transport Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierce, Eric M.; Bacon, Diana H.

2009-09-21

The interest in the long-term durability of waste glass stems from the need to predict radionuclide release rates from the corroding glass over geologic time-scales. Several long-term test methods have been developed to accelerate the glass-water reaction [drip test, vapor hydration test, product consistency test-B, and pressurized unsaturated flow (PUF)]. Currently, the PUF test is the only method that can mimic the unsaturated hydraulic properties expected in a subsurface disposal facility and simultaneously monitor the glass-water reaction. PUF tests are being conducted to accelerate the weathering of glass and validate the model parameters being used to predict long-term glass behavior.more » One dimensional reactive chemical transport simulations of glass dissolution and secondary phase formation during a 1.5-year long PUF experiment was conducted with the subsurface transport over reactive multi-phases (STORM) code. Results show that parameterization of the computer model by combining direct laboratory measurements and thermodynamic data provides an integrated approach to predicting glass behavior over geologic-time scales.« less

Fetal Bovine Collagen Matrix in the Treatment of a Full Thickness Burn Wound: A Case Report With Long-Term Follow-Up.

PubMed

Strong, Amy L; Bennett, Danielle K; Spreen, Elizabeth B; Adhvaryu, Dhaval V; Littleton, Jeffrey C; Mencer, Ernest J

2016-01-01

The treatment of full thickness skin wounds commonly associated with large burns continues to represent a challenging clinical entity. The current treatment for large TBSA burns is split thickness autologous skin grafting; however, this treatment often results in poor textural durability, hypertrophic scarring, and fibrotic contractures. In this case report, we describe our experience and long-term follow-up results after the application of fetal bovine collagen (FBC) matrix (PriMatrix, TEI Biosciences, Boston, MA) to burn wounds clinically assessed as full thickness that healed without the need for subsequent skin grafting. The patient presented with 25% TBSA burns and was debrided and covered with FBC on postburn day 7. By postoperative day 12, the patient had large areas of reepithelialization distributed throughout the wound bed. By postoperative day 26, the patient had significantly more areas of wound closure and was discharged. Reepithelialization and repigmentation continued, and long-term follow-up after 26 months demonstrated complete reepithelialization and nearly complete repigmentation, without the appearance of contractures or hypertrophic scarring. This case report highlights the use of FBC as a scaffold capable of dermal regeneration and spontaneous reepithelialization with an excellent long-term functional and cosmetic outcome.

Fetal Bovine Collagen Matrix in the Treatment of a Full Thickness Burn Wound: A Case Report With Long-Term Follow-Up

PubMed Central

Strong, Amy L.; Bennett, Danielle K.; Spreen, Elizabeth B.; Adhvaryu, Dhaval V.; Littleton, Jeffrey C.

2016-01-01

The treatment of full thickness skin wounds commonly associated with large burns continues to represent a challenging clinical entity. The current treatment for large TBSA burns is split thickness autologous skin grafting; however, this treatment often results in poor textural durability, hypertrophic scarring, and fibrotic contractures. In this case report, we describe our experience and long-term follow-up results after the application of fetal bovine collagen (FBC) matrix (PriMatrix, TEI Biosciences, Boston, MA) to burn wounds clinically assessed as full thickness that healed without the need for subsequent skin grafting. The patient presented with 25% TBSA burns and was debrided and covered with FBC on postburn day 7. By postoperative day 12, the patient had large areas of reepithelialization distributed throughout the wound bed. By postoperative day 26, the patient had significantly more areas of wound closure and was discharged. Reepithelialization and repigmentation continued, and long-term follow-up after 26 months demonstrated complete reepithelialization and nearly complete repigmentation, without the appearance of contractures or hypertrophic scarring. This case report highlights the use of FBC as a scaffold capable of dermal regeneration and spontaneous reepithelialization with an excellent long-term functional and cosmetic outcome. PMID:25494213

Comparison of cemented and uncemented fixation in total knee arthroplasty.

PubMed

Brown, Thomas E; Harper, Benjamin L; Bjorgul, Kristian

2013-05-01

As a result of reading this article, physicians should be able to :1. Understand the rationale behind using uncemented fixation in total knee arthroplasty.2.Discuss the current literature comparing cemented and uncemented total knee arthroplasty3. Describe the value of radiostereographic analysis in assessing implant stability.4. Appreciate the limitations in the available literature advocating 1 mode of fixation in total knee arthroplasty. Total knee arthroplasty performed worldwide uses either cemented, cementless, or hybrid (cementless femur with a cemented tibia) fixation of the components. No recent literature review concerning the outcomes of cemented vs noncemented components has been performed. Noncemented components offer the potential advantage of a biologic interface between the bone and implants, which could demonstrate the greatest advantage in long-term durable fixation in the follow-up of young patients undergoing arthroplasty. Several advances have been made in the backing of the tibial components that have not been available long enough to yield long-term comparative follow-up studies. Short-term radiostereographic analysis studies have yielded differing results. Although long-term, high-quality studies are still needed, material advances in biologic fixation surfaces, such as trabecular metal and hydroxyapatite, may offer promising results for young and active patients undergoing total knee arthroplasty when compared with traditional cemented options. Copyright 2013, SLACK Incorporated.

Volatile Reaction Products From Silicon-Based Ceramics in Combustion Environments Identified

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.

1997-01-01

Silicon-based ceramics and composites are prime candidates for use as components in the hot sections of advanced aircraft engines. These materials must have long-term durability in the combustion environment. Because water vapor is always present as a major product of combustion in the engine environment, its effect on the durability of silicon-based ceramics must be understood. In combustion environments, silicon-based ceramics react with water vapor to form a surface silica (SiO2) scale. This SiO2 scale, in turn, has been found to react with water vapor to form volatile hydroxides. Studies to date have focused on how water vapor reacts with high-purity silicon carbide (SiC) and SiO2 in model combustion environments. Because the combustion environment in advanced aircraft engines is expected to contain about 10-percent water vapor at 10-atm total pressure, the durability of SiC and SiO2 in gas mixtures containing 0.1- to 1-atm water vapor is of interest. The reactions of SiC and SiO2 with water vapor were monitored by measuring weight changes of sample coupons in a 0.5-atm water vapor/0.5-atm oxygen gas mixture with thermogravimetric analysis.

N-doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells

PubMed Central

Shui, Jianglan; Wang, Min; Du, Feng; Dai, Liming

2015-01-01

The availability of low-cost, efficient, and durable catalysts for oxygen reduction reaction (ORR) is a prerequisite for commercialization of the fuel cell technology. Along with intensive research efforts of more than half a century in developing nonprecious metal catalysts (NPMCs) to replace the expensive and scarce platinum-based catalysts, a new class of carbon-based, low-cost, metal-free ORR catalysts was demonstrated to show superior ORR performance to commercial platinum catalysts, particularly in alkaline electrolytes. However, their large-scale practical application in more popular acidic polymer electrolyte membrane (PEM) fuel cells remained elusive because they are often found to be less effective in acidic electrolytes, and no attempt has been made for a single PEM cell test. We demonstrated that rationally designed, metal-free, nitrogen-doped carbon nanotubes and their graphene composites exhibited significantly better long-term operational stabilities and comparable gravimetric power densities with respect to the best NPMC in acidic PEM cells. This work represents a major breakthrough in removing the bottlenecks to translate low-cost, metal-free, carbon-based ORR catalysts to commercial reality, and opens avenues for clean energy generation from affordable and durable fuel cells. PMID:26601132

N-doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells.

PubMed

Shui, Jianglan; Wang, Min; Du, Feng; Dai, Liming

2015-02-01

The availability of low-cost, efficient, and durable catalysts for oxygen reduction reaction (ORR) is a prerequisite for commercialization of the fuel cell technology. Along with intensive research efforts of more than half a century in developing nonprecious metal catalysts (NPMCs) to replace the expensive and scarce platinum-based catalysts, a new class of carbon-based, low-cost, metal-free ORR catalysts was demonstrated to show superior ORR performance to commercial platinum catalysts, particularly in alkaline electrolytes. However, their large-scale practical application in more popular acidic polymer electrolyte membrane (PEM) fuel cells remained elusive because they are often found to be less effective in acidic electrolytes, and no attempt has been made for a single PEM cell test. We demonstrated that rationally designed, metal-free, nitrogen-doped carbon nanotubes and their graphene composites exhibited significantly better long-term operational stabilities and comparable gravimetric power densities with respect to the best NPMC in acidic PEM cells. This work represents a major breakthrough in removing the bottlenecks to translate low-cost, metal-free, carbon-based ORR catalysts to commercial reality, and opens avenues for clean energy generation from affordable and durable fuel cells.

Polyimide Film of Increased Tear Strength

NASA Technical Reports Server (NTRS)

St. Clair, A. K.; Hinkley, J. A.; Ezzell, S. A.

1986-01-01

High-temperature linear aromatic polyimide with improved resistance to tearing made by new process that incorporates elastomer into polyimide. Linear aromatic condensation polyimides are materials of prime choice for use as films and coatings on advanced spacecraft and aircraft where durability at temperatures in range of 200 to 300 degree C required. Elastomer-containing polyimide film with improved toughness proves useful for applications where resistance to tearing and long-term thermal stability necessary. Desired resistance to tearing achieved by careful control of amount and chemical composition of added elastomer.

Design, ancillary testing, analysis and fabrication data for the advanced composite stabilizer for Boeing 737 aircraft, volume 2

NASA Technical Reports Server (NTRS)

Aniversario, R. B.; Harvey, S. T.; Mccarty, J. E.; Parsons, J. T.; Peterson, D. C.; Pritchett, L. D.; Wilson, D. R.; Wogulis, E. R.

1982-01-01

Results of tests conducted to demonstrate that composite structures save weight, possess long term durability, and can be fabricated at costs competitive with conventional metal structures are presented with focus on the use of graphite-epoxy in the design of a stabilizer for the Boeing 737 aircraft. Component definition, materials evaluation, material design properties, and structural elements tests are discussed. Fabrication development, as well as structural repair and inspection are also examined.

Considerations for a Standardized Test for Potential-Induced Degradation of Crystalline Silicon PV Modules (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hacke, P.

2012-03-01

Over the past decade, there have been observations of module degradation and power loss because of the stress that system voltage bias exerts. This results in part from qualification tests and standards note adequately evaluating for the durability of modules to the long-term effects of high voltage bias that they experience in fielded arrays. This talk deals with factors for consideration, progress, and information still needed for a standardized test for degradation due to system voltage stress.

Technical and Clinical Success and Long-Term Durability of Endovascular Treatment for Atherosclerotic Aortic Arch Branch Origin Obstruction: Evaluation of 144 Procedures.

PubMed

van de Weijer, M A J; Vonken, E J P A; de Vries, J-P P M; Moll, F L; Vos, J A; de Borst, G J

2015-07-01

Endovascular treatment of atherosclerotic obstruction of aortic arch branch origins (AABO) has largely replaced open surgery, but long-term outcome data are lacking. This study evaluated mid-term and long-term results of these procedures. Retrospective cohort study. Patients underwent endovascular treatment for symptomatic atherosclerotic stenosis of AABO between 1995 and 2012. Technical success was defined as uncomplicated revascularization and residual stenosis ≤30%. The primary end point was freedom from restenosis ≥50% on Duplex ultrasonography or magnetic resonance angiography. Secondary end points were freedom from target lesion revascularization or recurrent symptoms. 144 lesions were treated in 114 patients (75 female; mean age 66.3 years), by percutaneous transluminal angioplasty (PTA) in 20 patients and PTA and stent in 117 patients (brachiocephalic artery [BCA] 9/54; left common carotid artery [LCCA] 0/7; left subclavian artery [LSA] 11/56). The lesion could not be passed in four patients, and in three patients the intervention was terminated before angioplasty. The 30-day technical success was 94.4%, without deaths or strokes. Mean follow-up was 52.0 months (range 2-163 months). Restenosis-free survival was 95.6%, 92.9%, 87.6%, and 83.2% at 12, 24, 48, and 60 months, respectively. Log-rank test showed no significant difference between PTA only and PTA with additional stent placement at any point (p = .375), nor between BCA (n = 51), LCCA (n = 6), or LSA (n = 57). During follow-up, 27 patients (23.7%) became symptomatic (15 BCA, 1 LCCA, and 11 LSA); 19 patients with a restenosis of the target lesion (mean 56.7 months). Symptom-free survival was 94.7%, 92.0%, 82.3%, and 77.9% at 12, 24, 48, and 60 months, respectively. Endovascular treatment of aortic arch branch origin obstruction is safe and efficacious in experienced hands and can be considered as the preferred treatment, with good mid-term durability. Recurrent symptomatic lesions can be treated safely by renewed endovascular means. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Uncemented total hip arthroplasty in chronic hemodialysis patients

PubMed Central

Li, Wei-Chun; Shih, Chun-Hsiung; Ueng, Steve W; Shih, Hsin-Nung; Lee, Mel S

2010-01-01

Background and purpose Whether or not uncemented total hip arthroplasty (THA) can achieve durable fixation of implants to bone in patients on chronic hemodialysis is unknown. We analyzed the 2–13-year clinical outcomes of cementless THA in patients with end-stage renal diseases who were maintained on long-term hemodialysis. Patients and methods We reviewed the outcome of 23 consecutive uncemented THAs undertaken between 1993 and 2004, in patients with chronic renal failure who had been on long-term hemodialysis (2–18 years). 1 patient died and 2 patients were lost to follow-up within 2 years, leaving 20 hips (20 patients, median age 66 (38–81) years at the time of THA, 11 females) that were reviewed at median 7 (2–13) years postoperatively. Results Radiographic bone-ingrowth fixation of the components was found in 19 patients. 1 patient had aseptic loosening requiring revision surgery. The median d'Aubigne and Postel score was 10 (8–14) preoperatively and 15 (12–18) at final review. No prosthetic infections were found in any of the patients. Interpretation Uncemented THA shows promising medium-term results in patients receiving long-term hemodialysis. PMID:20175645

Mechanical characterization and numerical simulation of a subcutaneous implantable 3D printed cell encapsulation system.

PubMed

Adamo, Federica; Farina, Marco; Thekkedath, Usha R; Grattoni, Alessandro; Sesana, Raffaella

2018-06-01

Cell transplantation in bioengineered scaffolds and encapsulation systems has shown great promise in regenerative medicine. Depending on the site of implantation, type of cells and their expected function, these systems are designed to provide cells with a physiological-like environment while providing mechanical support and promoting long-term viability and function of the graft. A minimally invasive 3D printed system termed neovascularized implantable cell homing and encapsulation (NICHE) was developed in polylactic acid for subcutaneous transplantation of endocrine cells, including pancreatic islets. The suitability of the NICHE for long term in vivo deployment is investigated by assessing mechanical behavior of both fresh devices under simulated subcutaneous conditions and NICHE retrieved from subcutaneous implantation in pigs. Both experimental and numerical studies were performed with a focus on validating the constitutive material model used in the numerical analysis for accuracy and reliability. Notably, homogeneous isotropic constitutive material model calibrated by means of uniaxial testing well suited experimental results. The results highlight the long term durability for in vivo applications and the potential applicability of the model to predict the mechanical behavior of similar devices in various physiological settings. Copyright © 2018 Elsevier Ltd. All rights reserved.

Long-term Outcomes of Infliximab Use for Pediatric Crohn Disease: A Canadian Multicenter Clinical Practice Experience.

PubMed

deBruyn, Jennifer C; Jacobson, Kevan; El-Matary, Wael; Carroll, Matthew; Wine, Eytan; Wrobel, Iwona; Van Woudenberg, Mariel; Huynh, Hien Q

2018-02-01

Data on long-term real-world outcomes of infliximab in pediatric Crohn disease are limited. The aim of the study was to evaluate infliximab optimization and durability in children with Crohn disease. We performed a retrospective review of children with Crohn disease who started infliximab from January 2008 to December 2012 in 4 Canadian tertiary care centers. A priori factors associated with optimization and discontinuation from loss of response were evaluated using logistic regression and Cox proportional hazards model, respectively. One hundred eighty children (54.4% boys) started infliximab; all completed induction. Median age at infliximab start was 14.3 years (Q1, Q3: 12.8, 15.9 years) and median time from diagnosis to infliximab start was 1.5 years (Q1, Q3: 0.6, 3.5 years). At last follow-up, 87.1% were maintained on infliximab (median duration follow-up 85.9 weeks [Q1, Q3: 43.8, 138.8 weeks]). Infliximab optimization occurred in 57.3% (dose escalation 15.2%, interval shortening 3.9%, both 38.2%), primarily due to loss of response. Younger age at diagnosis (<10 years old) and nonstricturing, nonpenetrating behavior were associated with optimization (odds ratio 6.5, 95% confidence interval [CI] 2.0-21.1 and odds ratio 2.1, 95% CI 1.0-4.2, respectively). The 1- and 2-year durability of infliximab (percentage in follow-up who were continuing on infliximab) were 95.5% (95% CI 90.4-98.3) and 91.0% (95% CI 82.4-96.3), respectively. Annual discontinuation due to loss of response occurred at 3.2% per year (95% CI 1.1-5.2). Children with Crohn disease maintain a durable response to infliximab. Optimization occurs frequently and allows for continued use. Younger age at diagnosis and nonstricturing, nonpenetrating behavior are associated with increased need for infliximab optimization.

Valve-sparing aortic root replacement in patients with Marfan syndrome enrolled in the National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions.

PubMed

Song, Howard K; Preiss, Liliana R; Maslen, Cheryl L; Kroner, Barbara; Devereux, Richard B; Roman, Mary J; Holmes, Kathryn W; Tolunay, H Eser; Desvigne-Nickens, Patrice; Asch, Federico M; Milewski, Rita K; Bavaria, Joseph; LeMaire, Scott A

2014-05-01

The long-term outcomes of aortic valve-sparing (AVS) root replacement in Marfan syndrome (MFS) patients remain uncertain. The study aim was to determine the utilization and outcomes of AVS root replacement in MFS patients enrolled in the Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC). At the time of this analysis, 788 patients with MFS were enrolled in the GenTAC Registry, of whom 288 had undergone aortic root replacement. Patients who had undergone AVS procedures were compared to those who had undergone aortic valve replacement (AVR). AVS root replacement was performed in 43.5% of MFS patients, and the frequency of AVS was increased over the past five years. AVS patients were younger at the time of surgery (31.0 versus 36.3 years, p = 0.006) and more likely to have had elective rather than emergency surgery compared to AVR patients, in whom aortic valve dysfunction and aortic dissection was the more likely primary indication for surgery. After a mean follow up of 6.2 +/- 3.6 years, none of the 87 AVS patients had required reoperation; in contrast, after a mean follow up of 10.5 +/- 7.6 years, 11.5% of AVR patients required aortic root reoperation. Aortic valve function has been durable, with 95.8% of AVS patients having aortic insufficiency that was graded as mild or less. AVS root replacement is performed commonly among the MFS population, and the durability of the aortic repair and aortic valve function have been excellent to date. These results justify a continued use of the procedure in an elective setting. The GenTAC Registry will be a useful resource to assess the long-term durability of AVS root replacement in the future.

Seventy-five years of aggregate research in Kansas

DOT National Transportation Integrated Search

1999-03-01

The Kansas Department of Transportation (KDOT) has a long history of aggregate research directed towards finding the most reliable and durable aggregate for highway construction. Beginning with a study on freeze thaw durability in 1928, this paper su...

Long-term results of high-dose imatinib in children and adolescents with chronic myeloid leukaemia in chronic phase: the Italian experience.

PubMed

Giona, Fiorina; Putti, Maria C; Micalizzi, Concetta; Menna, Giuseppe; Moleti, Maria L; Santoro, Nicola; Iaria, Grazia; Ladogana, Saverio; Burnelli, Roberta; Consarino, Caterina; Varotto, Stefania; Tucci, Francesca; Messina, Chiara; Nanni, Mauro; Diverio, Daniela; Biondi, Andrea; Pession, Andrea; Locatelli, Franco; Piciocchi, Alfonso; Gottardi, Enrico; Saglio, Giuseppe; Foà, Robin

2015-08-01

Imatinib mesylate (IM) is used for the management of childhood chronic myeloid leukaemia (CML). The most effective dosage of IM and its long-term efficacy in children are not well defined. The purpose of this multicentre study is to report on the long-term results of high-dose IM (340 mg/m2 /d) in CML patients in chronic phase (CP-CML) aged <18 years at diagnosis. A total of 47 CP-CML patients with a median age at diagnosis of 11 years 9 months were enrolled in nine Italian centres. Complete cytogenetic response was achieved in 91.5% of the evaluable patients at a median time of 6 months. BCR-ABL1 International Scale ≤ 0.1% (major molecular response; MMR) and ≤0.01% (molecular response; MR) at 12 months were 66.6% and 33%, respectively. During follow-up, MMR and MR were achieved in 78.6% and 61% of children, respectively. IM was safely discontinued in 3 long-term treated children with a durable MR. Twelve patients (eight cytogenetic/molecular responders) underwent stem cell transplantation. The progression-free survival probabilities at 96 months for responding patients who continued IM and for those transplanted were 60% and 50%, respectively. After a median follow-up of 52 months (range 3-146), all patients are alive. High-dose IM is a long-term effective therapy in children and adolescents with CP-CML. © 2015 John Wiley & Sons Ltd.

Bond durability of universal adhesive to bovine enamel using self-etch mode.

PubMed

Suzuki, Soshi; Takamizawa, Toshiki; Imai, Arisa; Tsujimoto, Akimasa; Sai, Keiichi; Takimoto, Masayuki; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2018-04-01

The purpose of this study was to examine the enamel bond durability of universal adhesives in the self-etch mode under 2-year water storage and thermal cycling conditions. Three commercially available universal adhesives and a gold standard two-step self-etch adhesive were used. Ten specimens of bovine enamel were prepared per test group, and shear bond strength (SBS) was measured to determine the bonding durability after thermal cycling (TC) or long-term water storage (WS). The bonded specimens were divided into three groups: (1) specimens subjected to TC, where the bonded specimens were stored in 37 °C distilled water for 24 h before being subjected to 3000, 10,000, 20,000 or 30,000 TC; (2) specimens stored in 37 °C distilled water for 3 months, 6 months, 1 year or 2 year; and (3) specimens stored in 37 °C distilled water for 24 h, serving as a baseline. The two-step self-etch adhesive showed significantly higher SBS than the universal adhesives tested, regardless of the type of degradation method. All universal adhesives showed no significant enamel SBS reductions in TC and WS, when compared to baseline and the other degradation conditions. Compared to the bond strengths obtained with the two-step self-etch adhesive, significantly lower bond strengths were obtained with universal adhesives. However, the enamel bond durability of universal adhesives was relatively stable under both degradation conditions tested. The present data indicate that the enamel bond durability of universal adhesives in the self-etch mode might be sufficient for clinical use.

Tailored interfaces of unencapsulated perovskite solar cells for >1,000 hour operational stability

DOE PAGES

Christians, Jeffrey A.; Schulz, Philip; Tinkham, Jonathan S.; ...

2017-11-28

Long-term device stability is the most pressing issue that impedes perovskite solar cell commercialization, given the achieved 22.7% efficiency. The perovskite absorber material itself has been heavily scrutinized for being prone to degradation by water, oxygen and ultraviolet light. To date, most reports characterize device stability in the absence of these extrinsic factors. Here we show that, even under the combined stresses of light (including ultraviolet light), oxygen and moisture, perovskite solar cells can retain 94% of peak efficiency despite 1,000 hours of continuous unencapsulated operation in ambient air conditions (relative humidity of 10-20%). Each interface and contact layer throughoutmore » the device stack plays an important role in the overall stability which, when appropriately modified, yields devices in which both the initial rapid decay (often termed burn-in) and the gradual slower decay are suppressed. This extensively modified device architecture and the understanding developed will lead towards durable long-term device performance.« less

Tailored interfaces of unencapsulated perovskite solar cells for >1,000 hour operational stability

NASA Astrophysics Data System (ADS)

Christians, Jeffrey A.; Schulz, Philip; Tinkham, Jonathan S.; Schloemer, Tracy H.; Harvey, Steven P.; Tremolet de Villers, Bertrand J.; Sellinger, Alan; Berry, Joseph J.; Luther, Joseph M.

2018-01-01

Long-term device stability is the most pressing issue that impedes perovskite solar cell commercialization, given the achieved 22.7% efficiency. The perovskite absorber material itself has been heavily scrutinized for being prone to degradation by water, oxygen and ultraviolet light. To date, most reports characterize device stability in the absence of these extrinsic factors. Here we show that, even under the combined stresses of light (including ultraviolet light), oxygen and moisture, perovskite solar cells can retain 94% of peak efficiency despite 1,000 hours of continuous unencapsulated operation in ambient air conditions (relative humidity of 10-20%). Each interface and contact layer throughout the device stack plays an important role in the overall stability which, when appropriately modified, yields devices in which both the initial rapid decay (often termed burn-in) and the gradual slower decay are suppressed. This extensively modified device architecture and the understanding developed will lead towards durable long-term device performance.

Generation of a functional and durable vascular niche by the adenoviral E4ORF1 gene

PubMed Central

Seandel, Marco; Butler, Jason M.; Kobayashi, Hideki; Hooper, Andrea T.; White, Ian A.; Zhang, Fan; Vertes, Eva L.; Kobayashi, Mariko; Zhang, Yan; Shmelkov, Sergey V.; Hackett, Neil R.; Rabbany, Sina; Boyer, Julie L.; Rafii, Shahin

2008-01-01

Vascular cells contribute to organogenesis and tumorigenesis by producing unknown factors. Primary endothelial cells (PECs) provide an instructive platform for identifying factors that support stem cell and tumor homeostasis. However, long-term maintenance of PECs requires stimulation with cytokines and serum, resulting in loss of their angiogenic properties. To circumvent this hurdle, we have discovered that the adenoviral E4ORF1 gene product maintains long-term survival and facilitates organ-specific purification of PECs, while preserving their vascular repertoire for months, in serum/cytokine-free cultures. Lentiviral introduction of E4ORF1 into human PECs (E4ORF1+ ECs) increased the long-term survival of these cells in serum/cytokine-free conditions, while preserving their in vivo angiogenic potential for tubulogenesis and sprouting. Although E4ORF1, in the absence of mitogenic signals, does not induce proliferation of ECs, stimulation with VEGF-A and/or FGF-2 induced expansion of E4ORF1+ ECs in a contact-inhibited manner. Indeed, VEGF-A-induced phospho MAPK activation of E4ORF1+ ECs is comparable with that of naive PECs, suggesting that the VEGF receptors remain functional upon E4ORF1 introduction. E4ORF1+ ECs inoculated in implanted Matrigel plugs formed functional, patent, humanized microvessels that connected to the murine circulation. E4ORF1+ ECs also incorporated into neo-vessels of human tumor xenotransplants and supported serum/cytokine-free expansion of leukemic and embryonal carcinoma cells. E4ORF1 augments survival of PECs in part by maintaining FGF-2/FGF-R1 signaling and through tonic Ser-473 phosphorylation of Akt, thereby activating the mTOR and NF-κB pathways. Therefore, E4ORF1+ ECs establish an Akt-dependent durable vascular niche not only for expanding stem and tumor cells but also for interrogating the roles of vascular cells in regulating organ-specific vascularization and tumor neo-angiogenesis. PMID:19036927

Aortic cusp extension valvuloplasty with or without tricuspidization in children and adolescents: long-term results and freedom from aortic valve replacement.

PubMed

Polimenakos, Anastasios C; Sathanandam, Shyam; Elzein, Chawki; Barth, Mary J; Higgins, Robert S D; Ilbawi, Michel N

2010-04-01

Aortic cusp extension valvuloplasty is increasingly used in the management of children and adolescents with aortic stenosis or regurgitation. The durability of this approach and the freedom from valve replacement are not well defined. A study was undertaken to investigate outcomes. From July 1987 to November 2008, 142 patients aged less than 19 years underwent aortic cusp extension valvuloplasty in the form of pericardial cusp extension and tricuspidization (when needed). Three patients with truncus arteriosus and severe truncal valve insufficiency were excluded. From the available follow-up data of 139 patients, 50 had bicuspid aortic valves, 40 had congenital aortic valve stenosis, 41 had combined congenital aortic valve stenosis/insufficiency, and 8 had other diagnoses. Median follow-up was 14.4 years (0.1-21.4). Long-term mortality and freedom from aortic valve replacement were studied. There were no early, intermediate, or late deaths. Z-values of left ventricular end-diastolic dimension, aortic annulus, aortic sinus diameter, and sinotubular junction diameter before aortic valve replacement were 4.2 +/- 3.11, 2.3 +/- 1.25, 4.4 +/- 1.23, and 1.84 +/- 1.28, respectively. During the follow-up period, 64 patients underwent aortic valve reinterventions. The Ross procedure was performed in 32 of 139 patients (23%) undergoing aortic cusp extension valvuloplasty. Other aortic valve replacements were undertaken after 16 aortic cusp extension valvuloplasties (11.5%). Freedom from a second aortic cusp extension valvuloplasty or aortic valve replacement at 18 years was 82.1% +/- 4.2% and 60.0% +/- 7.2%, respectively. Aortic cusp extension valvuloplasty is a safe and effective surgical option with excellent survival and good long-term outcomes in children and adolescents. The procedure provides acceptable durability and satisfactory freedom from aortic valve replacement. Copyright 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Outcomes of ring versus suture annuloplasty for tricuspid valve repair in patients undergoing mitral valve surgery.

PubMed

Shinn, Sung Ho; Dayan, Victor; Schaff, Hartzell V; Dearani, Joseph A; Joyce, Lyle D; Lahr, Brian; Greason, Kevin L; Stulak, John M; Daly, Richard C

2016-08-01

There is controversy regarding the comparative effectiveness of methods of tricuspid valve (TV) repair-prosthetic ring versus suture annuloplasty-in patients undergoing operation for primary mitral valve (MV) disease. In this study, we analyzed factors associated with patient survival and recurrent tricuspid regurgitation (TR) following TV repair and focused on results stratified by method of tricuspid valve repair. We reviewed patients who underwent TV repair with suture (De Vega) or flexible ring annuloplasties at the time of MV surgery from 1995 to 2010. Patients with prior cardiac or concomitant aortic valve operations were excluded. Propensity matching was performed to account for potential differences in baseline characteristics between the groups. Primary outcomes were long-term mortality and postoperative TR grade. In the overall study, there were 415 patients with median age 72 years (range, 63-78 years), from which 148 matched pairs were identified by propensity score analysis. In the overall cohort, patients in the ring annuloplasty group more often had preoperative transvenous pacemakers (P = .05), lower ejection fractions (P = .028), and more recent years of operation (P < .001). For patients who had De Vega suture annuloplasty, long-term mortality was not different from that of patients who had ring annuloplasty (hazard ratio, 0.93; 95% confidence interval, 0.67-1.30). Older age, preoperative diabetes, and preoperative right ventricular dysfunction were predictors for long-term mortality. Durability of the annuloplasty methods was similar with no significant difference in trend of recurrent TR grades over follow-up (P = .807). Etiology of mitral regurgitation was not associated with recurrent TR during follow-up (P = .857). Late survival and TV durability following concomitant TV repair during MV surgery did not differ with respect to TV repair technique. In this series of patients with repaired tricuspid valves, etiology of MV disease did not influence postoperative changes in TR. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Long-term durability of sacral nerve stimulation therapy for chronic fecal incontinence.

PubMed

Hull, Tracy; Giese, Chad; Wexner, Steven D; Mellgren, Anders; Devroede, Ghislain; Madoff, Robert D; Stromberg, Katherine; Coller, John A

2013-02-01

Limited data have been published regarding the long-term results of sacral nerve stimulation, or sacral neuromodulation, for severe fecal incontinence. The aim was to assess the outcome of sacral nerve stimulation with the use of precise tools and data collection, focusing on the long-term durability of the therapy. Five-year data were analyzed. Patients entered in a multicenter, prospective study for fecal incontinence were followed at 3, 6, and 12 months and annually after device implantation. Patients with chronic fecal incontinence in whom conservative treatments had failed or who were not candidates for more conservative treatments were selected. Patients with ≥ 50% improvement over baseline in fecal incontinence episodes per week during a 14-day test stimulation period received sacral nerve stimulation therapy. Patients were assessed with a 14-day bowel diary and Fecal Incontinence Quality of Life and Fecal Incontinence Severity Index questionnaires. Therapeutic success was defined as ≥ 50% improvement over baseline in fecal incontinence episodes per week. All adverse events were collected. A total of 120 patients (110 women; mean age, 60.5 years) underwent implantation. Seventy-six of these patients (63%) were followed a minimum of 5 years (maximum, longer than 8 years) and are the basis for this report. Fecal incontinence episodes per week decreased from a mean of 9.1 at baseline to 1.7 at 5 years, with 89% (n = 64/72) having ≥ 50% improvement (p < 0.0001) and 36% (n = 26/72) having complete continence. Fecal Incontinence Quality of Life scores also significantly improved for all 4 scales between baseline and 5 years (n = 70; p < 0.0001). Twenty-seven of the 76 (35.5%) patients required a device revision, replacement, or explant. The therapeutic effect and improved quality of life for fecal incontinence is maintained 5 years after sacral nerve stimulation implantation and beyond. Device revision, replacement, or explant rate was acceptable, but future efforts should be aimed at improvement.

Bioprosthetic mitral valve replacement in patients aged 65 years or younger: long-term outcomes with the Carpentier-Edwards PERIMOUNT pericardial valve.

PubMed

Bourguignon, Thierry; Espitalier, Fabien; Pantaleon, Clémence; Vermes, Emmanuelle; El-Arid, Jean Marc; Loardi, Claudia; Karam, Elias; Candolfi, Pascal; Ivanes, Fabrice; Aupart, Michel

2018-02-12

Mitral valve replacement using a bioprosthesis remains controversial in young patients because data on long-term outcomes are missing. This study evaluated the long-term results of the PERIMOUNT pericardial mitral bioprosthesis in patients aged 65 years or younger. From 1984 to 2010, 148 Carpentier-Edwards PERIMOUNT mitral bioprostheses were implanted in 148 patients aged 65 years or younger. Baseline clinical, perioperative and follow-up data were recorded prospectively. Structural valve deterioration (SVD) was defined by strict echocardiographic assessment. The mean follow-up period was 8.6 ± 5.5 years, for a total of 1269 valve-years. Operative mortality rate was 2.0%. Fifty-one late deaths occurred (linearized rate 4.0% per valve-year). Actuarial survival rates averaged 70 ± 4%, 53 ± 6% and 31 ± 7% after 10, 15 and 20 years of follow-up, respectively. Actuarial freedom from SVD at 10, 15 and 20 years was 78 ± 5%, 47 ± 7% and 19 ± 7%, respectively. Reoperation was associated with no operative mortality. Actuarial freedom from reoperation due to SVD at 10, 15 and 20 years was 82 ± 4%, 50 ± 6% and 25 ± 8%, respectively. Competing risk analysis demonstrated an actual risk of explantation secondary to SVD at 20 years of 44 ± 5%. Expected valve durability was 14.2 years for this age group. In the selected patients aged 65 years or younger undergoing mitral valve replacement with a pericardial bioprosthesis, the expected valve durability was 14.2 years. Reoperation for SVD was associated with a low risk of mortality. © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Generation of a functional and durable vascular niche by the adenoviral E4ORF1 gene.

PubMed

Seandel, Marco; Butler, Jason M; Kobayashi, Hideki; Hooper, Andrea T; White, Ian A; Zhang, Fan; Vertes, Eva L; Kobayashi, Mariko; Zhang, Yan; Shmelkov, Sergey V; Hackett, Neil R; Rabbany, Sina; Boyer, Julie L; Rafii, Shahin

2008-12-09

Vascular cells contribute to organogenesis and tumorigenesis by producing unknown factors. Primary endothelial cells (PECs) provide an instructive platform for identifying factors that support stem cell and tumor homeostasis. However, long-term maintenance of PECs requires stimulation with cytokines and serum, resulting in loss of their angiogenic properties. To circumvent this hurdle, we have discovered that the adenoviral E4ORF1 gene product maintains long-term survival and facilitates organ-specific purification of PECs, while preserving their vascular repertoire for months, in serum/cytokine-free cultures. Lentiviral introduction of E4ORF1 into human PECs (E4ORF1(+) ECs) increased the long-term survival of these cells in serum/cytokine-free conditions, while preserving their in vivo angiogenic potential for tubulogenesis and sprouting. Although E4ORF1, in the absence of mitogenic signals, does not induce proliferation of ECs, stimulation with VEGF-A and/or FGF-2 induced expansion of E4ORF1(+) ECs in a contact-inhibited manner. Indeed, VEGF-A-induced phospho MAPK activation of E4ORF1(+) ECs is comparable with that of naive PECs, suggesting that the VEGF receptors remain functional upon E4ORF1 introduction. E4ORF1(+) ECs inoculated in implanted Matrigel plugs formed functional, patent, humanized microvessels that connected to the murine circulation. E4ORF1(+) ECs also incorporated into neo-vessels of human tumor xenotransplants and supported serum/cytokine-free expansion of leukemic and embryonal carcinoma cells. E4ORF1 augments survival of PECs in part by maintaining FGF-2/FGF-R1 signaling and through tonic Ser-473 phosphorylation of Akt, thereby activating the mTOR and NF-kappaB pathways. Therefore, E4ORF1(+) ECs establish an Akt-dependent durable vascular niche not only for expanding stem and tumor cells but also for interrogating the roles of vascular cells in regulating organ-specific vascularization and tumor neo-angiogenesis.

Development and Optimization of Tailored Composite TBC Design Architectures for Improved Erosion Durability

NASA Astrophysics Data System (ADS)

Schmitt, Michael P.; Schreiber, Jeremy M.; Rai, Amarendra K.; Eden, Timothy J.; Wolfe, Douglas E.

2017-08-01

Rare-earth pyrochlores, RE2Zr2O7, have been identified as potential thermal barrier coating (TBC) materials due to their attractive thermal properties and CMAS resistance. However, they possess a low fracture toughness which results in poor erosion durability/foreign object damage resistance. This research focuses on the development of tailored composite air plasma spray (APS) TBC design architectures utilizing a t' Low-k secondary toughening phase (ZrO2-2Y2O3-1Gd2O3-1Yb2O3; mol.%) to enhance the erosion durability of a hyper-stoichiometric pyrochlore, NZO (ZrO2-25Nd2O3-5Y2O3-5Yb2O3; mol.%). In this study, composite coatings have been deposited with 30, 50, and 70% (wt.%) t' Low-k toughening phase in a horizontally aligned lamellar morphology which enhances the toughening response of the coating. The coatings were characterized via SEM and XRD and were tested for erosion durability before and after isothermal heat treatment at 1100 °C. Analysis with mixing laws indicated improved erosion performance; however, a lack of long-term thermal stability was shown via isothermal heat treatments at 1316 °C. An impact stress analysis was performed using finite element analysis of a coating cross section, representing the first microstructurally realistic study of mechanical properties of TBCs with the results correlating well with observed behavior.

Microclimatic Variation Within Sleeve Cages Used in Ecological Studies

PubMed Central

Nelson, Lori A.; Rieske, Lynne K.

2014-01-01

Abstract Sleeve cages for enclosing or excluding arthropods are essential components of field studies evaluating trophic interactions. Microclimatic variation in sleeve cages was evaluated to characterize its potential effects on subsequent long-term experiments. Two sleeve cage materials, polyester and nylon, and two cage sizes, 400 and 6000 cm 2 , were tested on eastern hemlock, Tsuga canadensis (L.) Carrière. Temperature and relative humidity inside and outside cages, and the cost and durability of the cage materials, were compared. Long-term effects of the sleeve cages were observed by measuring new growth on T. canadensis branches. The ultimate goal was to identify a material that minimizes bag-induced microclimatic variation. Bagged branches whose microclimates mimic those of surrounding unbagged branches should have minimal effects on plant growth and may prove ideal venues for assessing herbivore and predator behavior under natural conditions. No differences were found in temperature or humidity between caging materials. Small cages had higher average temperatures than large cages, especially in the winter, but this difference was confounded by the fact that small cages were positioned higher in trees than large cages. Differences in plant growth were detected. Eastern hemlock branches enclosed within polyester cages produced fewer new growth tips than uncaged controls. Both polyester and nylon cages reduced the length of new shoot growth relative to uncaged branches. In spite of higher costs, nylon cages were superior to polyester with respect to durability and ease of handling. PMID:25368083

LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. E. O'Brien; R. C. O'Brien; X. Zhang

2011-11-01

Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cellmore » and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.« less

Modular bicompartmental knee arthroplasty : Indications, technique, prosthetic design, and results.

PubMed

Kanna, R

2017-03-01

The shifting demographics of patients with localized knee arthritis, including younger, more active patients, is a chief motivation for mounting interest in tissue preserving surgical substitutes for total knee arthroplasty (TKA). Unlinked, modular bi-compartmental knee arthroplasty (MBKA) is an emerging knee-resurfacing approach that provides a conservative alternative to TKA. Arthritis involving both patellofemoral and either medial or lateral tibiofemoral compartments, with no significant deformity or bone deficiency, preserved motion, and intact cruciate ligaments, can be effectively managed with MBKA. It is tailored to treat the pathologic areas of knees with bicompartmental arthritis with the benefit of improved function and tissue conservation. MBKA done in appropriate patients, using precise technique, with appropriate implants has shown to give good short and long term functional results. Long term results using modern MBKA implants are awaited and may further establish the durability and success of the procedure.

Long-term Isothermal Aging Effects on Weight Loss, Compression Properties, and Dimensions of T650-35 Fabric-reinforced PMR-15 Composites-data

NASA Technical Reports Server (NTRS)

Bowles, Kenneth J.; Tsuji, Luis; Kamvouris, John; Roberts, Gary D.

2003-01-01

A cooperative program was conducted with the General Electric Aircraft Engines plant in Evendale, Ohio, to study the effects of long-term isothermal aging at elevated temperatures on compression and thermal durability properties of T650 35 fabric-reinforced PMR 15 composites. This degradation study was conducted over an approximate time period of 3 1/2 yr. The aging temperatures were 204, 260, 288, 316, and 343 C. Specimens of different dimensions were evaluated. Specimens with ratios of the cut edge to total surface area of 0.03 to 0.89 were fabricated and aged. The aged and unaged specimens were tested in compression as specified in Test Method for Compressive Properties of Rigid Plastics (ASTM D695M). Thickness changes, degraded surface layer growth, weight loss, and failure modes were monitored and recorded. All property changes were thickness dependent.

Long-term stormwater quantity and quality performance of permeable pavement systems.

PubMed

Brattebo, Benjamin O; Booth, Derek B

2003-11-01

This study examined the long-term effectiveness of permeable pavement as an alternative to traditional impervious asphalt pavement in a parking area. Four commercially available permeable pavement systems were evaluated after 6 years of daily parking usage for structural durability, ability to infiltrate precipitation, and impacts on infiltrate water quality. All four permeable pavement systems showed no major signs of wear. Virtually all rainwater infiltrated through the permeable pavements, with almost no surface runoff. The infiltrated water had significantly lower levels of copper and zinc than the direct surface runoff from the asphalt area. Motor oil was detected in 89% of samples from the asphalt runoff but not in any water sample infiltrated through the permeable pavement. Neither lead nor diesel fuel were detected in any sample. Infiltrate measured 5 years earlier displayed significantly higher concentrations of zinc and significantly lower concentrations of copper and lead.

Time-Dependent Topology of Railway Prestressed Concrete Sleepers

NASA Astrophysics Data System (ADS)

Li, Dan; Ngamkhanong, Chayut; Kaewunruen, Sakdirat

2017-10-01

The railway sleepers are very important component of railway track structure. The sleepers can be manufactured by using timber, concrete, steel or other engineered materials. Nowadays, prestressed concrete has become most commonly used type of sleepers. Prestressed concrete sleepers have longer life-cycle and lower maintenance cost than reinforced concrete sleepers. They are expected to withstand high dynamic loads and harsh environments. However, durability and long-term performance of prestressed concrete sleepers are largely dependent on creep and shrinkage responses. This study investigates the long-term behaviours of prestressed concrete sleepers and proposes the shortening and deflection diagrams. Comparison between design codes of Eurocode 2 and AS3600-2009 provides the insight into the time-dependent performance of prestressed concrete sleepers. The outcome of this paper will improve the rail maintenance and inspection criteria in order to establish appropriate sensible remote track condition monitor network in practice.

Direct visual internal urethrotomy: Is it a durable treatment option?

PubMed Central

Pal, Dilip Kumar; Kumar, Sanjay; Ghosh, Bastab

2017-01-01

Objective: To evaluate the long-term success rate of direct vision internal urethrotomy as a treatment for anterior urethral strictures. Materials and Methods: We retrospectively analyzed the results for patients who underwent internal urethrotomy from January 2009 to January 2014 for anterior urethral strictures. Patients were followed till January 2016. Patients with complicated urethral strictures with a history of previous urethroplasty, hypospadias repair, or previous radiation were excluded from the study, as anticipated low success rate of direct visual internal urethrotomy (DVIU) in these patients. The Kaplan–Meier method was used to analyze stricture-free probability after the first, second, and third urethrotomy. Results: A total of 186 patients were included in this study. Stricture-free rates after first, second, and third urethrotomy were 29.66%, 22.64%, and 13.33%, respectively. Conclusions: Although DVIU may be a management option for anterior urethral stricture disease, it seems that long-term results are disappointing. PMID:28216923

Direct visual internal urethrotomy: Is it a durable treatment option?

PubMed

Pal, Dilip Kumar; Kumar, Sanjay; Ghosh, Bastab

2017-01-01

To evaluate the long-term success rate of direct vision internal urethrotomy as a treatment for anterior urethral strictures. We retrospectively analyzed the results for patients who underwent internal urethrotomy from January 2009 to January 2014 for anterior urethral strictures. Patients were followed till January 2016. Patients with complicated urethral strictures with a history of previous urethroplasty, hypospadias repair, or previous radiation were excluded from the study, as anticipated low success rate of direct visual internal urethrotomy (DVIU) in these patients. The Kaplan-Meier method was used to analyze stricture-free probability after the first, second, and third urethrotomy. A total of 186 patients were included in this study. Stricture-free rates after first, second, and third urethrotomy were 29.66%, 22.64%, and 13.33%, respectively. Although DVIU may be a management option for anterior urethral stricture disease, it seems that long-term results are disappointing.

Fiber-optic miniature sensor for in situ temperature monitoring of curing composite material

NASA Astrophysics Data System (ADS)

Sampath, Umesh; Kim, Dae-gil; Kim, Hyunjin; Song, Minho

2018-04-01

This study proposes a fiber-optic temperature sensor with a single-mode fiber tip covered with a thermo-sensitive polymer resin. The temperature is sensed by measuring the Fresnel reflection from the optical fiber/polymer interface. Because the thermo-optic coefficients differ between the optical fiber and the polymer, the in situ temperature can be measured even in curing composite materials. In initial experiments, the proposed sensor successfully measured and recovered the temperature information. The measured sensor data were linearly correlated, with an R2 exceeding 0.99. The standard deviation in the long-term measurements of constant temperature was 2.6%. The durability and stability of the sensor head material in long-term operation was validated by Fourier transform infrared spectroscopy and X-ray diffraction analysis. In further experiments, the suggested miniature temperature sensor obtained the internal temperatures of curing composite material over a wide range (30-110 °C).

Evidence-based outcomes of holmium laser enucleation of the prostate.

PubMed

Large, Tim; Krambeck, Amy E

2018-05-01

Holmium laser enucleation of the prostate (HoLEP) has been a mainstay therapy for the treatment of lower urinary tract symptoms (LUTS) secondary to benign prostate hyperplasia (BPH) for nearly 20 years. We briefly review current and sentinel publications that provide outcomes data after HoLEP. Current literature continues to support HoLEP as a versatile and durable surgical option for men with LUTS secondary to BPH. Despite evidence supporting durable symptom relief beyond 10 years even in large prostate glands, HoLEP is still not widely available to all patients. Concerns surrounding the learning curve of the procedure, high rates of retrograde ejaculation, and transient urinary incontinence seem to persist and limit the adoption of HoLEP by established urologists and residency training programs. Recent publications continue to show excellent short-term and long-term outcomes after HoLEP, in the categories of voiding function and patient satisfaction. Continued attempts to demonstrate equivalent outcomes of alternate-BPH surgical techniques are being met with renewed efforts by those performing HoLEP to demonstrate equivalent outcomes and patient safety during the learning phase of HoLEP for both mentored and self-directed surgical training.

Durability of aneurysm treatments in patients with active Behcet's disease.

PubMed

Elsharawy, Mohamed A; Elsaid, Aymen; Al-Dhafery, Bander; Alghnimi, Ibrahim; Almabyouq, Fatimah

2016-10-01

Aneurysms in Behcet's disease are rare, serious, and recurrent. To achieve durable treatment, patients should receive immunosuppressive therapy before intervention to induce remission. We present early and long-term results of emergency cases of active Behcet's disease, which did not permit waiting for suppressive treatment. The study was undertaken on all cases admitted to the vascular unit, King Fahd Hospital of University for aneurysm treatment in patients with active Behcet's disease over about 10 years. All patients had exclusion of the aneurysm either by open surgery or endovascular intervention. Morbidities and mortality were recorded within the hospital admission and on the follow-up. During the study period, three cases were included. All interventions were successful and lifesaving. However, two cases, treated with surgical interposition grafts, were blocked in the intermediate term follow-up (2-12 months) and one case, treated with endovascular treatment, complicated with pseudoaneurysm at femoral puncture site after six months. Although early results were good, intermediate ones were not satisfactory because of progressive graft thrombosis and formation of new aneurysms. Awareness of these rare cases help for early identification and proper immunosuppressive before emergency vascular intervention is warranted. © The Author(s) 2015.

Reach Out to Enhance Wellness Home-Based Diet-Exercise Intervention Promotes Reproducible and Sustainable Long-Term Improvements in Health Behaviors, Body Weight, and Physical Functioning in Older, Overweight/Obese Cancer Survivors

PubMed Central

Demark-Wahnefried, Wendy; Morey, Miriam C.; Sloane, Richard; Snyder, Denise C.; Miller, Paige E.; Hartman, Terryl J.; Cohen, Harvey J.

2012-01-01

Purpose Diet and exercise interventions have been tested in cancer survivors as a means to reduce late effects and comorbidity, but few have assessed adherence and health outcomes long term. Methods Between July 2005 and May 2007, the Reach Out to Enhance Wellness (RENEW) trial accrued 641 locoregionally staged, long-term (≥ 5 years from diagnosis) colorectal, breast, and prostate cancer survivors in the United States (21 states), Canada, and the United Kingdom. All participants were sedentary (< 150 minutes of physical activity [PA] a week), overweight or obese (body mass index, 25 to 40 kg/m2), and over age 65 years. The trial tested a diet-exercise intervention delivered via mailed print materials and telephone counseling. RENEW used a wait-list control, cross-over design (ie, participants received the year-long intervention immediately or after a 1-year delay), which allowed the opportunity to assess program efficacy (previously reported primary outcome), durability, and reproducibility (reported herein). Measures included diet quality (DQ), PA, BMI, and physical function (PF). Results No significant relapse was observed in the immediate-intervention arm for DQ, PA, and BMI; however, rates of functional decline increased when the intervention ceased. From year 1 to year 2, significant improvements were observed in the delayed-intervention arm; mean change scores in behaviors and BMI and PF slopes were as follows: DQ score, 5.2 (95% CI, 3.4 to 7.0); PA, 45.8 min/wk (95% CI, 26.9 to 64.6 min/wk); BMI, −0.56 (95% CI, −0.75 to −0.36); and Short Form-36 PF, −1.02 versus −5.52 (P < .001 for all measures). Overall, both arms experienced significant improvements in DQ, PA, and BMI from baseline to 2-year follow-up (P < .001). Conclusion Older cancer survivors respond favorably to lifestyle interventions and make durable changes in DQ and PA that contribute to sustained weight loss. These changes positively reorient functional decline trajectories during intervention delivery. PMID:22614994

Durability of certain configurations for providing skid resistance on concrete pavements.

DOT National Transportation Integrated Search

1974-01-01

The main objective of this study was to establish the factors that influence the durability of the surface configurations that are used or can be used to provide high and long lasting skid resistance for portland cement concrete pavements. In the dev...

The long-term in vivo behavior of polymethyl methacrylate bone cement in total hip arthroplasty.

PubMed

Oonishi, Hiroyuki; Akiyama, Haruhiko; Takemoto, Mitsuru; Kawai, Toshiyuki; Yamamoto, Koji; Yamamuro, Takao; Oonishi, Hironobu; Nakamura, Takashi

2011-10-01

The long-term success of cemented total hip arthroplasty (THA) has been well established. Improved outcomes, both radiographically and clinically, have resulted mainly from advances in stem design and improvements in operating techniques. However, there is concern about the durability of bone cement in vivo. We evaluated the physical and chemical properties of CMW1 bone cements retrieved from patients undergoing revision THA. CMW1 cements were retrieved from 14 patients who underwent acetabular revision because of aseptic loosening. The time in vivo before revision was 7-30 years. The bending properties of the retrieved bone cement were assessed using the three-point bending method. The molecular weight and chemical structure were analyzed by gel permeation chromatography and Fourier-transform infrared spectroscopy. The porosity of the bone cements was evaluated by 3-D microcomputer tomography. The bending strength decreased with increasing time in vivo and depended on the density of the bone cement, which we assume to be determined by the porosity. There was no correlation between molecular weight and time in vivo. The infrared spectra were similar in the retrieved cements and in the control CMW1 cements. Our results indicate that polymer chain scission and significant hydrolysis do not occur in CMW1 cement after implantation in vivo, even in the long term. CMW1 cement was stable through long-term implantation and functional loading.

Study on basalt fiber parameters affecting fiber-reinforced mortar

NASA Astrophysics Data System (ADS)

Orlov, A. A.; Chernykh, T. N.; Sashina, A. V.; Bogusevich, D. V.

2015-01-01

This article considers the effect of different dosages and diameters of basalt fibers on tensile strength increase during bending of fiberboard-reinforced mortar samples. The optimal dosages of fiber, providing maximum strength in bending are revealed. The durability of basalt fiber in an environment of cement, by means of microscopic analysis of samples of fibers and fiberboard-reinforced mortar long-term tests is examined. The article also compares the behavior of basalt fiber in the cement stone environment to a glass one and reveals that the basalt fiber is not subject to destruction.

Atomic oxygen effects on materials

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Brady, Joyce A.; Merrow, James E.

1989-01-01

Understanding of the basic processes of atomic oxygen interaction is currently at a very elementary level. However, measurement of erosion yields, surface morphology, and optical properties for low fluences have brought about much progress in the past decade. Understanding the mechanisms and those factors that are important for proper simulation of low Earth orbit is at a much lower level of understanding. The ability to use laboratory simulations with confidence to quantifiably address the functional performance and durability of materials in low Earth orbit will be necessary to assure long-term survivability to the natural space environment.

Therapy of primary CNS lymphoma with methotrexate-based chemotherapy and deferred radiotherapy: preliminary results.

PubMed

Cher, L; Glass, J; Harsh, G R; Hochberg, F H

1996-06-01

Disease-free survival in primary CNS lymphoma has improved with the advent of methotrexate-based pre-irradiation chemotherapy. Prolonged response durations have been noted in six of eight patients refusing radiation therapy in two of our prior series. We have treated an additional 11 patients with methotrexate-based chemotherapy without subsequent planned irradiation. Some received maintenance chemotherapy. Most have had durable responses with little or no toxicity. Prolonged responses can be maintained without radiation therapy, thus avoiding potential long-term radiation toxicity.

Develop and test fuel cell powered on-site integrated total energy systems. Phase 3: Full-scale power plant development

NASA Technical Reports Server (NTRS)

Kaufman, A.; Olson, B.; Pudick, S.; Wang, C. L.; Werth, J.; Whelan, J. A.

1986-01-01

The testing of two 25-cell stacks of the 13 inch x 23 inch cell size (about 4kW) was carried out for 7000 and 8400 hours, respectively. A 25kW stack containing 175 cells of the same size and based on the same technology was constructed and is on test. A third 4kW stack, which will contain 24 cells, will comprise several new technology features; these will be assesed for performance and durability in long-term testing.

Strength and reliability analysis of metal-composite overwrapped pressure vessel

NASA Astrophysics Data System (ADS)

Burov, A. E.; Lepikhin, A. M.; Moskvichev, V. V.

2017-12-01

Metal-composite overwrapped pressure vessels (MCOPV) have found a wide application in aerospace and aeronautical industries. Such vessels should combine impermeability and high weight efficiency with enhanced long-term safety and durability. To meet these requirements, theoretical and experimental studies on the mechanics of deformation and failure of MCOPV are required. In the paper, the analysis on strength, lifetime and reliability of MCOPV is presented. A high performance of the MCOPV is justified by comparing the calculation results with experiment data obtained on full-scale samples.

Revisiting the role of durable polymers in cardiovascular devices.

PubMed

Mori, Hiroyoshi; Otsuka, Fumiyuki; Gupta, Anuj; Jinnouchi, Hiroyuki; Torii, Sho; Harari, Emanuel; Virmani, Renu; Finn, Aloke V

2017-11-01

Polymers are an essential component of drug-eluting stents (DES) used to control drug release but remain the most controversial component of DES technology. There are two types of polymers employed in DES: durable polymer based DES (DP-DES) and biodegradable polymer DES (BP-DES). First-generation DES were exclusively composed of DP and demonstrated increased rates of late stent failure due in part to poor polymer biocompatibility. Newer generations DES use more biocompatible durable polymers or biodegradable polymers. Areas covered: We will cover issues identified with 1st-generation DP-DES, areas of success and failure in 2nd-generation DP-DES and examine the promise and shortcomings of BP-DES. Briefly, fluorinated polymers used in 2nd-generation DP-DES have excellent anti-thrombogenicity and better biocompatibility than 1st-generation DES polymers. However, these devices lead to persistent drug exposure to the endothelium which impairs endothelial function and predisposes towards neoatherosclerosis. Meanwhile, BP-DES has shortened the duration of drug exposure which might be beneficial for endothelial functional recovery leading to less neoatherosclerosis. However, it remains uncertain whether the long-term biocompatibility of bare metal surfaces is better than that of polymer-coated metals. Expert commentary: Each technology has distinct advantages, which can be optimized depending upon the particular characteristics of the patient being treated.

Extended Durability Testing of an External Fuel Processor for a Solid Oxide Fuel Cell (SOFC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mark Perna; Anant Upadhyayula; Mark Scotto

2012-11-05

Durability testing was performed on an external fuel processor (EFP) for a solid oxide fuel cell (SOFC) power plant. The EFP enables the SOFC to reach high system efficiency (electrical efficiency up to 60%) using pipeline natural gas and eliminates the need for large quantities of bottled gases. LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) is developing natural gas-fired SOFC power plants for stationary power applications. These power plants will greatly benefit the public by reducing the cost of electricity while reducing the amount of gaseous emissions of carbon dioxide, sulfur oxides,more » and nitrogen oxides compared to conventional power plants. The EFP uses pipeline natural gas and air to provide all the gas streams required by the SOFC power plant; specifically those needed for start-up, normal operation, and shutdown. It includes a natural gas desulfurizer, a synthesis-gas generator and a start-gas generator. The research in this project demonstrated that the EFP could meet its performance and durability targets. The data generated helped assess the impact of long-term operation on system performance and system hardware. The research also showed the negative impact of ambient weather (both hot and cold conditions) on system operation and performance.« less

The Network of Excellence 'Knowledge-based Multicomponent Materials for Durable and Safe Performance'

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, Arnaldo

The Network of Excellence 'Knowledge-based Multicomponent Materials for Durable and Safe Performance' (KMM-NoE) consists of 36 institutional partners from 10 countries representing leading European research institutes and university departments (25), small and medium enterprises, SMEs (5) and large industry (7) in the field of knowledge-based multicomponent materials (KMM), more specifically in intermetallics, metal-ceramic composites, functionally graded materials and thin layers. The main goal of the KMM-NoE (currently funded by the European Commission) is to mobilise and concentrate the fragmented scientific potential in the KMM field to create a durable and efficient organism capable of developing leading-edge research while spreading themore » accumulated knowledge outside the Network and enhancing the technological skills of the related industries. The long-term strategic goal of the KMM-NoE is to establish a self-supporting pan-European institution in the field of knowledge-based multicomponent materials--KMM Virtual Institute (KMM-VIN). It will combine industry oriented research with educational and training activities. The KMM Virtual Institute will be founded on three main pillars: KMM European Competence Centre, KMM Integrated Post-Graduate School, KMM Mobility Programme. The KMM-NoE is coordinated by the Institute of Fundamental Technological Research (IPPT) of the Polish Academy of Sciences, Warsaw, Poland.« less

Crystallization in high-level waste glass: A review of glass theory and noteworthy literature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christian, J. H.

2015-08-01

There is a fundamental need to continue research aimed at understanding nepheline and spinel crystal formation in high-level waste (HLW) glass. Specifically, the formation of nepheline solids (K/NaAlSiO₄) during slow cooling of HLW glass can reduce the chemical durability of the glass, which can cause a decrease in the overall durability of the glass waste form. The accumulation of spinel solids ((Fe, Ni, Mn, Zn)(Fe,Cr)₂O₄), while not detrimental to glass durability, can cause an array of processing problems inside of HLW glass melters. In this review, the fundamental differences between glass and solid-crystals are explained using kinetic, thermodynamic, and viscositymore » arguments, and several highlights of glass-crystallization research, as it pertains to high-level waste vitrification, are described. In terms of mitigating spinel in the melter and both spinel and nepheline formation in the canister, the complexity of HLW glass and the intricate interplay between thermal, chemical, and kinetic factors further complicates this understanding. However, new experiments seeking to elucidate the contributing factors of crystal nucleation and growth in waste glass, and the compilation of data from older experiments, may go a long way towards helping to achieve higher waste loadings while developing more efficient processing strategies.« less

Renal Angiomyolipoma: Mid- to Long-Term Results Following Embolization with Onyx.

PubMed

Thulasidasan, Narayanan; Sriskandakumar, Srividhiya; Ilyas, Shahzad; Sabharwal, Tarun

2016-12-01

Percutaneous transcatheter embolization is currently the preferred treatment for ruptured or enlarging renal angiomyolipoma (AML), although the optimum choice of embolic material has not yet been established. We present mid- to long-term outcomes following embolization of AMLs with Onyx. Ten AMLs in seven patients (including two with tuberous sclerosis) were embolized with Onyx. Patients were followed-up clinically, with tumour size and renal function measured pre- and post-procedure. Mean pre-treatment AML size was 63.4 mm (range 42-100). Mean clinical follow-up was 431.4 days (range 153-986) and imaging follow-up 284.2 days (range 30-741). There was no haemorrhage from treated lesions within the follow-up period. Of patients who had cross-sectional imaging pre- and post-procedure, mean decrease in AML size of 22 mm was seen after Onyx embolization (p = 0.0058, 95 % CI 9.13-34.87). No significant difference between serum creatinine was seen pre- and post-procedure (p = 0.54, 95 % CI 8.63-4.85). Onyx embolization of renal AMLs is effective in the medium to long term, with theoretical benefits in safety and durability of result.

Water Absorption Behavior of Hemp Hurds Composites

PubMed Central

Stevulova, Nadezda; Cigasova, Julia; Purcz, Pavol; Schwarzova, Ivana; Kacik, Frantisek; Geffert, Anton

2015-01-01

In this paper, water sorption behavior of 28 days hardened composites based on hemp hurds and inorganic binder was studied. Two kinds of absorption tests on dried cube specimens in deionized water bath at laboratory temperature were performed. Short-term (after one hour water immersion) and long-term (up to 180 days) water absorption tests were carried out to study their durability. Short-term water sorption behavior of original hemp hurds composites depends on mean particle length of hemp and on binder nature. The comparative study of long-term water sorption behavior of composites reinforced with original and chemically modified hemp hurds in three reagents confirmed that surface treatment of filler influences sorption process. Based on evaluation of sorption curves using a model for composites based on natural fibers, diffusion of water molecules in composite reinforced with original and chemically modified hemp hurds is anomalous in terms of the Fickian behavior. The most significant decrease in hydrophility of hemp hurds was found in case of hemp hurds modified by NaOH and it relates to change in the chemical composition of hemp hurds, especially to a decrease in average degree of cellulose polymerization as well as hemicellulose content.

Self-Healing Superhydrophobic Materials Showing Quick Damage Recovery and Long-Term Durability.

PubMed

Wang, Liming; Urata, Chihiro; Sato, Tomoya; England, Matt W; Hozumi, Atsushi

2017-09-26

Superhydrophobic coatings/materials are important for a wide variety of applications, but the majority of these man-made coatings/materials still suffer from poor durability because of their lack of self-healing ability. Here, we report novel superhydrophobic materials which can quickly self-heal from various severe types of damage. In this study, we used poly(dimethylsiloxane) (PDMS) infused with two liquids: trichloropropylsilane, which reacts with ambient moisture to self-assemble into grass-like microfibers (named silicone micro/nanograss) on the surfaces and low-viscosity silicone oil (SO), which remains within the PDMS matrices and acts as a self-healing agent. Because of the silicone micro/nanograss structures on the PDMS surfaces and the effective preserve/protection system of a large quantity of SO within the PDMS matrices, our superhydrophobic materials showed quick superhydrophobic recovery under ambient conditions (within 1-2 h) even after exposure to plasma (24 h), boiling water, chemicals, and outside environments. Such an ability is superior to the best self-healing superhydrophobic coatings/materials reported so far.

Overview of existing cartilage repair technology.

PubMed

McNickle, Allison G; Provencher, Matthew T; Cole, Brian J

2008-12-01

Currently, autologous chondrocyte implantation and osteochondral grafting bridge the gap between palliation of cartilage injury and resurfacing via arthroplasty. Emerging technologies seek to advance first generation techniques and accomplish several goals including predictable outcomes, cost-effective technology, single-stage procedures, and creation of durable repair tissue. The biologic pipeline represents a variety of technologies including synthetics, scaffolds, cell therapy, and cell-infused matrices. Synthetic constructs, an alternative to biologic repair, resurface a focal chondral defect rather than the entire joint surface. Scaffolds are cell-free constructs designed as a biologic "net" to augment marrow stimulation techniques. Minced cartilage technology uses stabilized autologous or allogeneic fragments in 1-stage transplantation. Second and third generation cell-based methods include alternative membranes, chondrocyte seeding, and culturing onto scaffolds. Despite the promising early results of these products, significant technical obstacles remain along with unknown long-term durability. The vast array of developing technologies has exceptional promise and the potential to revolutionize the cartilage treatment algorithm within the next decade.

Durability of symmetric-structured metal-supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Tucker, Michael C.

2017-11-01

Symmetric-structure metal-supported solid oxide fuel cells (MS-SOFC) with YSZ electrolyte are fabricated with porous YSZ backbone electrodes, stainless steel supports, and infiltrated catalysts on both anode and cathode side. Durability towards aggressive thermal and redox cycling, and long-term operation is assessed. Many sealing material candidates are screened for compatibility with the cell materials and operating conditions, and a commercial sealing glass, GM31107, is selected. LSM/SDCN cells are then subjected to 200 very fast thermal cycles and 20 complete redox cycles, with minimal impact to cell performance. LSM/SDCN and SDCN/SDCN cells are operated for more than 1200 h at 700 °C. The seal and cell hermeticity is maintained, and cell ohmic impedance does not change significantly during operation. Electrode polarization increases during operation, leading to significant degradation of the cell performance. In-operando EIS and post-mortem SEM/EDS analysis suggest that catalyst coarsening and cathode Cr deposition are the dominant degradation modes.

Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis J.

2015-01-01

Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

From coagulation to enucleation: the use of lasers in surgery for benign prostatic hyperplasia.

PubMed

Wilson, Liam C; Gilling, Peter J

2005-09-01

The application of lasers for the treatment of benign prostatic hyperplasia has evolved over the past 15 years. Early-generation neodymium:yttrium aluminum garnet lasers were used to coagulate and ablate prostatic tissue, but significant postoperative irritative symptoms and high reoperation rates meant that this approach did not seriously challenge the status quo for long. Ablative techniques have recently become popular again with the marketing of the newer-generation, higher-power potassium titanyl phosphate and holmium lasers. Although short-term data are encouraging, there are no comparative trials of significant duration, so it is not yet possible to draw conclusions with regard to efficacy and durability. The holmium laser can also be used as an incisional and dissecting tool that allows resection or enucleation of whole lobes of the prostate, mimicking the action of the index finger in open prostatectomy. The safety, efficacy, durability and cost-effectiveness of the holmium laser have been shown in well-designed randomized controlled trials.

One-volt-driven superfast polymer actuators based on single-ion conductors

PubMed Central

Kim, Onnuri; Kim, Hoon; Choi, U. Hyeok; Park, Moon Jeong

2016-01-01

The key challenges in the advancement of actuator technologies related to artificial muscles include fast-response time, low operation voltages and durability. Although several researchers have tackled these challenges over the last few decades, no breakthrough has been made. Here we describe a platform for the development of soft actuators that moves a few millimetres under 1 V in air, with a superfast response time of tens of milliseconds. An essential component of this actuator is the single-ion-conducting polymers that contain well-defined ionic domains through the introduction of zwitterions; this achieved an exceptionally high dielectric constant of 76 and a 300-fold enhancement in ionic conductivity. Moreover, the actuator demonstrated long-term durability, with negligible changes in the actuator stroke over 20,000 cycles in air. Owing to its low-power consumption (only 4 mW), we believe that this actuator could pave the way for cutting-edge biomimetic technologies in the future. PMID:27857067

Why does lag affect the durability of memory-based automaticity: loss of memory strength or interference?

PubMed

Wilkins, Nicolas J; Rawson, Katherine A

2013-10-01

In Rickard, Lau, and Pashler's (2008) investigation of the lag effect on memory-based automaticity, response times were faster and proportion of trials retrieved was higher at the end of practice for short lag items than for long lag items. However, during testing after a delay, response times were slower and proportion of trials retrieved was lower for short lag items than for long lag items. The current study investigated the extent to which the lag effect on the durability of memory-based automaticity is due to interference or to the loss of memory strength with time. Participants repeatedly practiced alphabet subtraction items in short lag and long lag conditions. After practice, half of the participants were immediately tested and the other half were tested after a 7-day delay. Results indicate that the lag effect on the durability of memory-based automaticity is primarily due to interference. We discuss potential modification of current memory-based processing theories to account for these effects. © 2013.

Long-Term Outcome of Gamma Knife Radiosurgery for Treatment of Typical Trigeminal Neuralgia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jung Ho; Kim, Dong Gyu, E-mail: gknife@plaza.snu.ac.k; Chung, Hyun-Tai

2009-11-01

Purpose: To analyze the long-term outcomes of patients with typical trigeminal neuralgia treated with gamma knife radiosurgery (GKRS). Patients and Methods: A total of 62 consecutive patients with typical trigeminal neuralgia were treated with GKRS between 1998 and 2004. Of the 62 patients, 2 were lost to follow-up; the remaining 60 patients were followed for >12 months. The mean prescribed maximal dose was 79.7 Gy (range, 75-80), using a 4-mm shot. Results: Of the 60 patients, 48 were followed for >4 years. An additional 3 patients, followed for <4 years, experienced recurrent pain after a favorable initial response and weremore » incorporated into the long-term response analysis. Of these 51 patients (mean age, 61 +- 11 years; 37 women [72.5%]; and mean follow-up duration, 58 +- 14 months), 46 (90.2%) responded to GKRS, as demonstrated by an improvement in their Barrow Neurological Institute pain intensity score. Of the 46 patients, 24 (52.2%) had pain recurrence. The actuarial recurrence-free survival rate was 84.8%, 76.1%, 69.6%, 63.0%, and 45.8% at 1, 2, 3, 4, and 5 years after radiosurgery, respectively. Patient age >70 years correlated with a favorable outcome in terms of pain recurrence after radiosurgery (hazard ratio, 0.125; 95% confidence interval, 0.016-0.975; p = .047) on multivariate analysis. Conclusion: GKRS seems to be an effective treatment modality for patients with typical trigeminal neuralgia considering the initial response rate; however, fewer than one-half of patients might continue to benefit from GKRS after long-term follow-up. Elderly patients might be good candidates for radiosurgery considering the long-term durability of efficacy.« less

Adaptive Evolution and Environmental Durability Jointly Structure Phylodynamic Patterns in Avian Influenza Viruses

PubMed Central

Roche, Benjamin; Drake, John M.; Brown, Justin; Stallknecht, David E.; Bedford, Trevor; Rohani, Pejman

2014-01-01

Avian influenza viruses (AIVs) have been pivotal to the origination of human pandemic strains. Despite their scientific and public health significance, however, there remains much to be understood about the ecology and evolution of AIVs in wild birds, where major pools of genetic diversity are generated and maintained. Here, we present comparative phylodynamic analyses of human and AIVs in North America, demonstrating (i) significantly higher standing genetic diversity and (ii) phylogenetic trees with a weaker signature of immune escape in AIVs than in human viruses. To explain these differences, we performed statistical analyses to quantify the relative contribution of several potential explanations. We found that HA genetic diversity in avian viruses is determined by a combination of factors, predominantly subtype-specific differences in host immune selective pressure and the ecology of transmission (in particular, the durability of subtypes in aquatic environments). Extending this analysis using a computational model demonstrated that virus durability may lead to long-term, indirect chains of transmission that, when coupled with a short host lifespan, can generate and maintain the observed high levels of genetic diversity. Further evidence in support of this novel finding was found by demonstrating an association between subtype-specific environmental durability and predicted phylogenetic signatures: genetic diversity, variation in phylogenetic tree branch lengths, and tree height. The conclusion that environmental transmission plays an important role in the evolutionary biology of avian influenza viruses—a manifestation of the “storage effect”—highlights the potentially unpredictable impact of wildlife reservoirs for future human pandemics and the need for improved understanding of the natural ecology of these viruses. PMID:25116957

Bio-inspired crosslinking and matrix-drug interactions for advanced wound dressings with long-term antimicrobial activity.

PubMed

Dhand, Chetna; Venkatesh, Mayandi; Barathi, Veluchami Amutha; Harini, Sriram; Bairagi, Samiran; Goh Tze Leng, Eunice; Muruganandham, Nandhakumar; Low, Kenny Zhi Wei; Fazil, Mobashar Hussain Urf Turabe; Loh, Xian Jun; Srinivasan, Dinesh Kumar; Liu, Shou Ping; Beuerman, Roger W; Verma, Navin Kumar; Ramakrishna, Seeram; Lakshminarayanan, Rajamani

2017-09-01

There is a growing demand for durable advanced wound dressings for the management of persistent infections after deep burn injuries. Herein, we demonstrated the preparation of durable antimicrobial nanofiber mats, by taking advantage of strong interfacial interactions between polyhydroxy antibiotics (with varying number of OH groups) and gelatin and their in-situ crosslinking with polydopamine (pDA) using ammonium carbonate diffusion method. Polydopamine crosslinking did not interfere with the antimicrobial efficacy of the loaded antibiotics. Interestingly, incorporation of antibiotics containing more number of alcoholic OH groups (N OH  ≥ 5) delayed the release kinetics with complete retention of antimicrobial activity for an extended period of time (20 days). The antimicrobials-loaded mats displayed superior mechanical and thermal properties than gelatin or pDA-crosslinked gelatin mats. Mats containing polyhydroxy antifungals showed enhanced aqueous stability and retained nanofibrous morphology under aqueous environment for more than 4 weeks. This approach can be expanded to produce mats with broad spectrum antimicrobial properties by incorporating the combination of antibacterial and antifungal drugs. Direct electrospinning of vancomycin-loaded electrospun nanofibers onto a bandage gauze and subsequent crosslinking produced non-adherent durable advanced wound dressings that could be easily applied to the injured sites and readily detached after treatment. In a partial thickness burn injury model in piglets, the drug-loaded mats displayed comparable wound closure to commercially available silver-based dressings. This prototype wound dressing designed for easy handling and with long-lasting antimicrobial properties represents an effective option for treating life-threatening microbial infections due to thermal injuries. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Precast concrete pavement - systems and performance review

NASA Astrophysics Data System (ADS)

Novak, Josef; Kohoutková, Alena; Křístek, Vladimír; Vodička, Jan

2017-09-01

Long-term traffic restrictions belong to the key disadvantages of conventional cast-in-plane concrete pavements which have been used for technical structures such as roads, parking place and airfield pavements. As a consequence, the pressure is put on the development of such systems which have short construction time, low production costs, long-term durability, low maintenance requirements etc.. The paper presents the first step in the development of an entirely new precast concrete pavement (PCP) system applicable to airfield and highway pavements. The main objective of the review of PCP systems is to acquire a better understanding of the current systems and design methods used for transport infrastructure. There is lack of information on using PCP systems for the construction of entirely new pavements. To most extensive experience is dated back to the 20th century when hexagonal slab panels and system PAG were used in the Soviet Union for the military airfields. Since cast-in-situ pavements became more common, the systems based on precast concrete panels have been mainly utilized for the removal of damaged sections of existing structures including roads, highways etc.. Namely, it concerns Fort Miller Super Slab system, Michigan system, Uretek Stitch system and Kwik system. The presented review indicates several issues associated with the listed PCP systems and their applications to the repair and rehabilitation of existing structures. Among others, the type of manufacturing technology, particularly the position of slots for dowel bars, affects the durability and performance of the systems. Gathered information serve for the development of a new system for airfield and highway pavement construction.

Aortic Root Biomechanics After Sleeve and David Sparing Techniques: A Finite Element Analysis.

PubMed

Tasca, Giordano; Selmi, Matteo; Votta, Emiliano; Redaelli, Paola; Sturla, Francesco; Redaelli, Alberto; Gamba, Amando

2017-05-01

Aortic root aneurysm can be treated with valve-sparing procedures. The David and Yacoub techniques have shown excellent long-term results but are technically demanding. Recently, a new and simpler procedure, the Sleeve technique, was proposed with encouraging results. We aimed to quantify the biomechanics of the initially aneurysmal aortic root (AR) after the Sleeve procedure to assess whether it induces abnormal stresses, potentially undermining its durability. Two finite element (FE) models of the physiologic and aneurysmal AR were built, accounting for the anatomical asymmetry and the nonlinear and anisotropic mechanical properties of human AR tissues. On the aneurysmal model, the Sleeve and David techniques were simulated based on the corresponding published technical features. Aortic root biomechanics throughout 2 consecutive cardiac cycles were computed in each simulated configuration. Both sparing techniques restored physiologic-like kinematics of aortic valve (AV) leaflets but induced different leaflets stresses. The time course averaged over the leaflets' bellies was 35% higher in the David model than in the Sleeve model. Commissural stresses, which were equal to 153 and 318 kPa in the physiologic and aneurysmal models, respectively, became 369 and 208 kPa in the David and Sleeve models, respectively. No intrinsic structural problems were detected in the Sleeve model that might jeopardize the durability of the procedure. If corroborated by long-term clinical outcomes, the results obtained suggest that using this new technique could successfully simplify the surgical repair of AR aneurysms and reduce intraoperative complications. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

On the effects of leaflet microstructure and constitutive model on the closing behavior of the mitral valve

PubMed Central

Lee, Chung-Hao; Rabbah, Jean-Pierre; Yoganathan, Ajit P.; Gorman, Robert C.; Gorman, Joseph H.

2016-01-01

Recent long-term studies showed an unsatisfactory recurrence rate of severe mitral regurgitation 3–5 years after surgical repair, suggesting that excessive tissue stresses and the resulting strain-induced tissue failure are potential etiological factors controlling the success of surgical repair for treating mitral valve (MV) diseases. We hypothesized that restoring normal MV tissue stresses in MV repair techniques would ultimately lead to improved repair durability through the restoration of MV normal homeostatic state. Therefore, we developed a micro- and macro- anatomically accurate MV finite element model by incorporating actual fiber microstructural architecture and a realistic structure-based constitutive model. We investigated MV closing behaviors, with extensive in vitro data used for validating the proposed model. Comparative and parametric studies were conducted to identify essential model fidelity and information for achieving desirable accuracy. More importantly, for the first time, the interrelationship between the local fiber ensemble behavior and the organ-level MV closing behavior was investigated using a computational simulation. These novel results indicated not only the appropriate parameter ranges, but also the importance of the microstructural tuning (i.e., straightening and re-orientation) of the collagen/elastin fiber networks at the macroscopic tissue level for facilitating the proper coaptation and natural functioning of the MV apparatus under physiological loading at the organ level. The proposed computational model would serve as a logical first step toward our long-term modeling goal—facilitating simulation-guided design of optimal surgical repair strategies for treating diseased MVs with significantly enhanced durability. PMID:25947879

Long-term durability of one-step adhesive-composite systems to enamel and dentin.

PubMed

Foxton, Richard M; Melo, Luciana; Stone, David G; Pilecki, Peter; Sherriff, Martin; Watson, Timothy F

2008-01-01

This study evaluated the long-term durability of three one-step adhesive-composite systems to ground enamel and dentin. Twenty-seven teeth were randomly divided into three groups of nine. The first group had its crowns sectioned to expose superficial dentin, which was then ground with 600 grit SiC paper. One of three one-step adhesives: a trial bonding agent, OBF-2; i Bond or Adper Prompt L-Pop was applied to the dentin of three teeth and built-up with the corresponding resin composite (Estelite sigma, Venus or Filtek Supreme). The second group of nine teeth had their enamel approximal surfaces ground with wet 600-grit SiC paper, then one of the three one-step adhesives was applied and built-up with resin composite. The bonded specimens were sliced into 0.7 mm-thick slabs. After 24 hours and one year of water storage at 37 degrees C, the slabs were sectioned into beams for the microtensile bond strength test. Failure modes were observed using optical and electron scanning microscopy. The third group of nine teeth had approximal wedge-shaped cavities prepared above the CEJ into dentin. Two-to-three grains of rhodamine B were added to each of the three adhesives prior to restoring the cavities with resin composite. After 24 hours storage, the teeth were sectioned and their interfaces examined with a laser scanning confocal microscope. The bond strengths of the three adhesive-composite systems to both enamel and dentin significantly lessened after one year of water storage, however, there was no significant difference between the materials.

Endovascular treatment of mycotic aortic aneurysms: a European multicenter study.

PubMed

Sörelius, Karl; Mani, Kevin; Björck, Martin; Sedivy, Petr; Wahlgren, Carl-Magnus; Taylor, Peter; Clough, Rachel E; Lyons, Oliver; Thompson, Matt; Brownrigg, Jack; Ivancev, Krassi; Davis, Meryl; Jenkins, Michael P; Jaffer, Usman; Bown, Matt; Rancic, Zoran; Mayer, Dieter; Brunkwall, Jan; Gawenda, Michael; Kölbel, Tilo; Jean-Baptiste, Elixène; Moll, Frans; Berger, Paul; Liapis, Christos D; Moulakakis, Konstantinos G; Langenskiöld, Marcus; Roos, Håkan; Larzon, Thomas; Pirouzram, Artai; Wanhainen, Anders

2014-12-09

Mycotic aortic aneurysm (MAA) is a rare and life-threatening disease. The aim of this European multicenter collaboration was to study the durability of endovascular aortic repair (EVAR) of MAA, by assessing late infection-related complications and long-term survival. All EVAR treated MAAs, between 1999 and 2013 at 16 European centers, were retrospectively reviewed. One hundred twenty-three patients with 130 MAAs were identified. Mean age was 69 years (range 39-86), 87 (71%) were men, 58 (47%) had immunodeficiency, and 47 (38%) presented with rupture. Anatomic locations were ascending/arch (n=4), descending (n=34), paravisceral (n=15), infrarenal aorta (n=63), and multiple (n=7). Treatments were thoracic EVAR (n=43), fenestrated/branched EVAR (n=9), and infrarenal EVAR (n=71). Antibiotic was administered for mean 30 weeks. Mean follow-up was 35 months (range 1 week to 149 months). Six patients (5%) were converted to open repair during follow-up. Survival was 91% (95% confidence interval, 86% to 96%), 75% (67% to 83%), 55% (44% to 66%), and 41% (28% to 54%) after 1, 12, 60, and 120 months, respectively. Infection-related death occurred in 23 patients (19%), 9 after discontinuation of antibiotic treatment. A Cox regression analysis demonstrated non-Salmonella-positive culture as predictors for late infection-related death. Endovascular treatment of MAA is feasible and for most patients a durable treatment option. Late infections do occur, are often lethal, and warrant long-term antibiotic treatment and follow-up. Patients with non-Salmonella-positive blood cultures were more likely to die from late infection. © 2014 American Heart Association, Inc.

Compress knee arthroplasty has 80% 10-year survivorship and novel forms of bone failure.

PubMed

Healey, John H; Morris, Carol D; Athanasian, Edward A; Boland, Patrick J

2013-03-01

Compliant, self-adjusting compression technology is a novel approach for durable prosthetic fixation of the knee. However, the long-term survival of these constructs is unknown. We therefore determined the survival of the Compress prosthesis (Biomet Inc, Warsaw, IN, USA) at 5 and 10 actuarial years and identified the failure modes for this form of prosthetic fixation. We retrospectively reviewed clinical and radiographic records for all 82 patients who underwent Compress knee arthroplasty from 1998 to 2008, as well as one patient who received the device elsewhere but was followed at our institution. Prosthesis survivorship and modes of failure were determined. Followup was for a minimum of 12 months or until implant removal (median, 43 months; range, 6-131 months); 28 patients were followed for more than 5 years. We found a survivorship of 85% at 5 years and 80% at 10 years. Eight patients required prosthetic revision after interface failure due to aseptic loosening alone (n = 3) or aseptic loosening with periprosthetic fracture (n = 5). Additionally, five periprosthetic bone failures occurred that did not require revision: three patients had periprosthetic bone failure without fixation compromise and two exhibited irregular prosthetic osteointegration patterns with concomitant fracture due to mechanical insufficiency. Compress prosthetic fixation after distal femoral tumor resection exhibits long-term survivorship. Implant failure was associated with patient nonadherence to the recommended weightbearing proscription or with bone necrosis and fracture. We conclude this is the most durable FDA-approved fixation method for distal femoral megaprostheses. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Long-term effects of interference on short-term memory performance in the rat.

PubMed

Missaire, Mégane; Fraize, Nicolas; Joseph, Mickaël Antoine; Hamieh, Al Mahdy; Parmentier, Régis; Marighetto, Aline; Salin, Paul Antoine; Malleret, Gaël

2017-01-01

A distinction has always been made between long-term and short-term memory (also now called working memory, WM). The obvious difference between these two kinds of memory concerns the duration of information storage: information is supposedly transiently stored in WM while it is considered durably consolidated into long-term memory. It is well acknowledged that the content of WM is erased and reset after a short time, to prevent irrelevant information from proactively interfering with newly stored information. In the present study, we used typical WM radial maze tasks to question the brief lifespan of spatial WM content in rodents. Groups of rats were submitted to one of two different WM tasks in a radial maze: a WM task involving the repetitive presentation of a same pair of arms expected to induce a high level of proactive interference (PI) (HIWM task), or a task using a different pair in each trial expected to induce a low level of PI (LIWM task). Performance was effectively lower in the HIWM group than in LIWM in the final trial of each training session, indicative of a "within-session/short-term" PI effect. However, we also observed a different "between-session/long-term" PI effect between the two groups: while performance of LIWM trained rats remained stable over days, the performance of HIWM rats dropped after 10 days of training, and this impairment was visible from the very first trial of the day, hence not attributable to within-session PI. We also showed that a 24 hour-gap across training sessions known to allow consolidation processes to unfold, was a necessary and sufficient condition for the long-term PI effect to occur. These findings suggest that in the HIWM task, WM content was not entirely reset between training sessions and that, in specific conditions, WM content can outlast its purpose by being stored more permanently, generating a long-term deleterious effect of PI. The alternative explanation is that WM content could be transferred and stored more permanently in an intermediary form or memory between WM and long-term memory.

Long-lasting antifog plasma modification of transparent plastics.

PubMed

Di Mundo, Rosa; d'Agostino, Riccardo; Palumbo, Fabio

2014-10-08

Antifog surfaces are necessary for any application requiring optical efficiency of transparent materials. Surface modification methods aimed toward increasing solid surface energy, even when supposed to be permanent, in fact result in a nondurable effect due to the instability in air of highly hydrophilic surfaces. We propose the strategy of combining a hydrophilic chemistry with a nanotextured topography, to tailor a long-lasting antifog modification on commercial transparent plastics. In particular, we investigated a two-step process consisting of self-masked plasma etching followed by plasma deposition of a silicon-based film. We show that the deposition of the silicon-based coatings on the flat (pristine) substrates allows a continuous variation of wettability from hydrophobic to superhydrophilic, due to a continuous reduction of carbon-containing groups, as assessed by Fourier transform infrared and X-ray photoelectron spectroscopies. By depositing these different coatings on previously nanotextured substrates, the surface wettability behavior is changed consistently, as well as the condensation phenomenon in terms of microdroplets/liquid film appearance. This variation is correlated with advancing and receding water contact angle features of the surfaces. More importantly, in the case of the superhydrophilic coating, though its surface energy decreases with time, when a nanotextured surface underlies it, the wetting behavior is maintained durably superhydrophilic, thus durably antifog.

Chronic animal experiment with magnetically suspended centrifugal pump.

PubMed

Yamada, T; Nishimura, K; Park, C H; Kono, S; Yuasa, S; Tsukiya, T; Akamatsu, T; Matsuda, K; Ban, T

1997-07-01

We have been developing a new type of centrifugal pump for long-term use. The magnetically suspended centrifugal pump (MSCP) contains no shaft and seal so that long life expectancy is predicted. Paracorporeal left ventricular (LV) assist circulation between the left atrium and the descending aorta was instituted using sheep. The flow rates ranged from 2.5-5.5 L/min. The sheep that lived the longest (46 days) died of an embolism as a result of the thrombus in the pump. No thrombus formation was observed in other pumps. Plasma free hemoglobin levels ranged from 9 to 18 mg/dl, which led to the conclusion that the hemolysis level remained within an acceptable range. Two driving modes were compared. The slope of the pressure-flow relationship plot under a constant motor current mode was steeper than that under a constant rotational speed mode, and thus, the flow fluctuation decreased. In conclusion, the MSCP is durable for more than a month at the current stage of development and is a promising device for long-term ventricular assist.

Campus Involvement as a Predictor for Durable Leadership Development in Conjunction with Leadership Program Participation

ERIC Educational Resources Information Center

Rosch, David M.; Stephens, Clinton M.

2017-01-01

Postsecondary educators have long been faced with the challenge of developing the leadership capacity of their students. This research investigated the following research question: To what degree do formal opportunities for involvement predict durable growth in leadership capacity in students who participate in a formal leadership development…

Aortic Valve Replacement With the Stentless Freedom SOLO Bioprosthesis: A Systematic Review.

PubMed

Wollersheim, Laurens W; Li, Wilson W; Bouma, Berto J; Repossini, Alberto; van der Meulen, Jan; de Mol, Bas A

2015-10-01

This systematic review examined the clinical and hemodynamic performance of the stentless Freedom SOLO (Sorin Group, Milan, Italy) aortic bioprosthesis. The occurrence of postoperative thrombocytopenia was also analyzed. The Freedom SOLO is safe to use in everyday practice, with short cross-clamp times, and postoperative pacemaker implantation is notably lower. Valvular gradients are low and remain stable during short-term follow-up. Thrombocytopenia is more severe than in other aortic prostheses; however, this is without clinical consequences. Within a few years, the 15-year follow-up of this bioprosthesis will be known, which will be key to evaluating its long-term durability. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Aggressive treatment of idiopathic axillo-subclavian vein thrombosis provides excellent long-term function.

PubMed

Stone, David H; Scali, Salvatore T; Bjerk, Aja A; Rzucidlo, Eva; Chang, Catherine K; Goodney, Philip P; Nolan, Brian W; Walsh, Daniel B

2010-07-01

While much attention has been devoted toward treatment paradigms for idiopathic axillo-subclavian vein thrombosis (ASVT), little has focused on long-term durability of aggressive treatment and its associated functional outcomes. The purpose of this study was to review our own surgical therapeutic algorithm and its associated durability and functional outcomes. All patients treated with combined endovascular and open surgery at Dartmouth-Hitchcock Medical Center for ASVT from 1988 to 2008 were identified. Patient demographics, comorbidities, and operative techniques were recorded. Patency, freedom from reintervention, and functional outcomes were documented. Follow-up via telephone and clinic visit allowed quantitative comparison of functional status, pre- and postoperatively. Thirty-six patients were treated for ASVT throughout the study interval. Seven patients (19.4%) were lost to follow-up. Most patients were male (66%; N = 24); mean age was 32 years. Catheter-directed thrombolysis was utilized in the majority of patients (83.3%; N = 30) with an average time from symptom onset to lysis of 12 days. Surgical decompression was undertaken in all patients via transaxillary (52%; N = 19), supraclavicular (31%; N = 11), or infraclavicular approaches (17%; N = 6). Eleven stents were placed in 11 patients (30.5%) for residual stenotic disease. Mean follow-up was 65 months, with 1- and 5-year overall patency at 100% and 94%, respectively. Freedom from reintervention was 100% and 74.4% at 1 and 5 years, respectively. Seven patients (19.4%) required postoperative reintervention with four receiving additional lytic therapy, two requiring a stent, and one venoplasty. At presentation, 65.5% (N = 19) of patients were unable to work or perform routine activities. After treatment, 86% (N = 25) returned to their employment and have experienced sustained symptomatic and functional improvement. Patients with symptomatic idiopathic axillo-subclavian vein thrombosis can expect durable patency with sustained freedom from reintervention following aggressive combined endovascular and surgical treatment. Good functional outcomes can be expected in patients with relief of symptoms and return to work. Copyright (c) 2010 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

Modified fabrication techniques lead to improved centrifugal blood pump performance.

PubMed

Pacella, J J; Goldstein, A H; Magovern, G J; Clark, R F

1994-01-01

The authors are developing an implantable centrifugal blood pump for short- and medium-term (1-6 months) left ventricular assist. They hypothesized that the application of result dependent modifications to this pump would lead to overall improved performance in long-term implantation studies. Essential requirements for pump operation, such as durability and resistance to clot formation, have been achieved through specialized fabrication techniques. The antithrombogenic character of the pump has been improved through coating at the cannula-housing interfaces and the baffle seal, and through changing the impeller blade material from polysulfone to pyrolytic carbon. The electronic components of the pump have been sealed for implantable use through specialized processes of dipping and potting, and the surfaces of the internal pump components have been treated to increase durability. The device has demonstrated efficacy in five chronic sheep implantation studies of 14, 10, 28, 35, and 154 day duration. Post mortem findings from the 14 day experiment showed stable fibrin entangled around the impeller shaft and blades. After pump modification, autopsy findings of the 10 day study showed no evidence of clot. Additionally, the results of the 28 day experiment showed only a small (2.0 mm) ring of fibrin at the shaft-seal interface. In the 35 and 154 day experiments, redesign of the stators have resulted in improved motor corrosion resistance. The 35 day study showed a small, 0.5 mm wide fibrin deposit at the lip seal, but no motor failure. In the 154 day experiment, the motor failed because of stator fluid corrosion, while the explanted pump was devoid of thrombus. Based on these findings, the authors believe that these pump refinements have contributed significantly to improvements in durability and resistance to clot formation.

d-Cycloserine enhances durability of social skills training in autism spectrum disorder.

PubMed

Wink, Logan K; Minshawi, Noha F; Shaffer, Rebecca C; Plawecki, Martin H; Posey, David J; Horn, Paul S; Adams, Ryan; Pedapati, Ernest V; Schaefer, Tori L; McDougle, Christopher J; Swiezy, Naomi B; Erickson, Craig A

2017-01-01

d-Cycloserine (DCS) enhances extinction learning across species, but it has proven challenging to identify consistent benefit of DCS when added to therapeutic interventions. We conducted a placebo-controlled trial of DCS to potentiate social skills training in autism spectrum disorder (ASD) but found substantial improvement in both the DCS and placebo groups at the conclusion of active treatment. Here, we assess the impact of DCS 11 weeks following active treatment to evaluate the impact of DCS on treatment response durability. Study participants included 60 outpatient youth with ASD, ages 5-11 years, all with IQ above 70, and significantly impaired social functioning who completed a 10-week active treatment phase during which they received weekly single doses of 50 mg of DCS or placebo administered 30 min prior to group social skills training. Following the 10-week active treatment phase, blinded follow-up assessments occurred at week 11 and week 22. The primary outcome measure for our durability of treatment evaluation was the parent-rated social responsiveness scale (SRS) total raw score at week 22. Analysis of the SRS total raw score demonstrated significant decrease for the DCS group compared to the placebo group ( p  = 0.042) indicating greater maintenance of treatment effect in the DCS group. DCS was well tolerated, with irritability being the most frequently reported adverse effect in both groups. The findings of this study suggest that DCS may help youth with ASD to maintain skills gained during sort-term social skills training. Larger-scale studies with longer follow-up will be necessary to further understand the long-term impact of DCS paired with structured social skills training. ClinicalTrials.gov, NCT01086475.

Durability Testing of Biomass Based Oxygenated Fuel Components in a Compression Ignition Engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratcliff, Matthew A; McCormick, Robert L; Baumgardner, Marc E.

Blending cellulosic biofuels with traditional petroleum-derived fuels results in transportation fuels with reduced carbon footprints. Many cellulosic fuels rely on processing methods that produce mixtures of oxygenates which must be upgraded before blending with traditional fuels. Complete oxygenate removal is energy-intensive and it is likely that such biofuel blends will necessarily contain some oxygen content to be economically viable. Previous work by our group indicated that diesel fuel blends with low levels (<4%-vol) of oxygenates resulted in minimal negative effects on short-term engine performance and emissions. However, little is known about the long-term effects of these compounds on engine durabilitymore » issues such as the impact on fuel injection, in-cylinder carbon buildup, and engine oil degradation. In this study, four of the oxygenated components previously tested were blended at 4%-vol in diesel fuel and tested with a durability protocol devised for this work consisting of 200 hrs of testing in a stationary, single-cylinder, Yanmar diesel engine operating at constant load. Oil samples, injector spray patterns, and carbon buildup from the injector and cylinder surfaces were analyzed. It was found that, at the levels tested, these fuels had minimal impact on the overall engine operation, which is consistent with our previous findings.« less

International Low-Earth-Orbit Spacecraft Materials Test Program Initiated for Better Prediction of Durability and Performance

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.

1999-01-01

Spacecraft in low Earth orbit (LEO) are subjected to many components of the environment, which can cause them to degrade much more rapidly than intended and greatly shorten their functional life. The atomic oxygen, ultraviolet radiation, and cross contamination present in LEO can affect sensitive surfaces such as thermal control paints, multilayer insulation, solar array surfaces, and optical surfaces. The LEO Spacecraft Materials Test (LEO-SMT) program is being conducted to assess the effects of simulated LEO exposure on current spacecraft materials to increase understanding of LEO degradation processes as well as to enable the prediction of in-space performance and durability. Using ground-based simulation facilities to test the durability of materials currently flying in LEO will allow researchers to compare the degradation evidenced in the ground-based facilities with that evidenced on orbit. This will allow refinement of ground laboratory test systems and the development of algorithms to predict the durability and performance of new materials in LEO from ground test results. Accurate predictions based on ground tests could reduce development costs and increase reliability. The wide variety of national and international materials being tested represent materials being functionally used on spacecraft in LEO. The more varied the types of materials tested, the greater the probability that researchers will develop and validate predictive models for spacecraft long-term performance and durability. Organizations that are currently participating in the program are ITT Research Institute (USA), Lockheed Martin (USA), MAP (France), SOREQ Nuclear Research Center (Israel), TNO Institute of Applied Physics (The Netherlands), and UBE Industries, Ltd. (Japan). These represent some of the major suppliers of thermal control and sensor materials currently flying in LEO. The participants provide materials that are exposed to selected levels of atomic oxygen, vacuum ultraviolet radiation, contamination, or synergistic combined environments at the NASA Lewis Research Center. Changes in characteristics that could affect mission performance or lifetime are then measured. These characteristics include changes in mass, solar absorptance, and thermal emittance. The durability of spacecraft materials from U.S. suppliers is then compared with those of materials from other participating countries. Lewis will develop and validate performance and durability prediction models using this ground data and available space data. NASA welcomes the opportunity to consider additional international participants in this program, which should greatly aid future spacecraft designers as they select materials for LEO missions.

Mid-urethral slings in female incontinence: Current status

PubMed Central

Krlin, Ryan M.; Murphy, Alana M.; Ingber, Michael S.; Vasavada, Sandip P.

2011-01-01

The advent of the mid-urethral sling (MUS) 15 years ago has drastically changed the surgical management of stress urinary incontinence (SUI). Both retropubic and transobturator MUS can be placed in the ambulatory setting with excellent results. The tension-free vaginal tape (TVT) sling has the most robust and long-term data, but more recent literature suggests that the transobturator tape sling may offer comparable efficacy in appropriately selected patients. Single incision sling (SIS) is the newest addition to the MUS group and was developed in an attempt to minimize morbidity and create an anti-incontinence procedure that could be performed in the office. The efficacy of SIS remains unknown as the current literature regarding SIS lacks long-term results and comparative trials. The suprapubic arc sling appears to have equally effective outcomes in at least the short-term when compared with TVT. Although evolution of the SIS has led to a less invasive procedure with decreased post-op pain and reduced recovery time, durability of efficacy could be the endpoint we are sacrificing. Until longer-term data and more quality comparison trials are available, tailoring one's choice of MUS to the individual patient and her unique clinical parameters remains the best option. PMID:22022053

The long-term in vivo behavior of polymethyl methacrylate bone cement in total hip arthroplasty

PubMed Central

2011-01-01

Background and purpose The long-term success of cemented total hip arthroplasty (THA) has been well established. Improved outcomes, both radiographically and clinically, have resulted mainly from advances in stem design and improvements in operating techniques. However, there is concern about the durability of bone cement in vivo. We evaluated the physical and chemical properties of CMW1 bone cements retrieved from patients undergoing revision THA. Methods CMW1 cements were retrieved from 14 patients who underwent acetabular revision because of aseptic loosening. The time in vivo before revision was 7–30 years. The bending properties of the retrieved bone cement were assessed using the three-point bending method. The molecular weight and chemical structure were analyzed by gel permeation chromatography and Fourier-transform infrared spectroscopy. The porosity of the bone cements was evaluated by 3-D microcomputer tomography. Results The bending strength decreased with increasing time in vivo and depended on the density of the bone cement, which we assume to be determined by the porosity. There was no correlation between molecular weight and time in vivo. The infrared spectra were similar in the retrieved cements and in the control CMW1 cements. Interpretation Our results indicate that polymer chain scission and significant hydrolysis do not occur in CMW1 cement after implantation in vivo, even in the long term. CMW1 cement was stable through long-term implantation and functional loading. PMID:22103279

Long-term results after aortic valve replacement with the Biocor PSB stentless xenograft in the elderly.

PubMed

Luciani, G B; Santini, F; Auriemma, S; Barozzi, L; Bertolini, P; Mazzucco, A

2001-05-01

This study seeks to define the long-term results after Biocor PSB stentless aortic valve replacement (AVR) in elderly patients, including the effects of No-React treatment. We reviewed the outcomes of 106 consecutive patients, aged 70+/-6 years, having Biocor PSB (93 standard, 13 No-React) AVR between October 1992 and October 1996. There were three early deaths (3%) and 15 late deaths (15%), during a mean follow-up of 5.8+/-1.6 years. At 8 years, survival was 82%+/-4% and freedom from cardiac death was 94%+/-3%. Freedom from valve failure was 92%+/-4% at 8 years (No-React: 92%+/-8% at 4 years). Replacement of the xenograft was required in 5 patients. Freedom from reoperation was 91%+/-4% at 8 years (No-React: 92%+/-8% at 4 years). Four bleeding and two embolic events were recorded: overall valve-related event-free survival was 81%+/-7% at 8 years (No-React: 76%+/-12% at 4 years). Age of long-term survivors averaged 77+/-5 years and their New York Heart Association status was 1.3+/-0.6 (versus 2.9+/-0.6 preoperatively, p = 0.01). Satisfactory freedom from cardiac events and from valve deterioration added to uniform improvement in functional status despite advanced age and high prevalence of comorbid conditions make AVR with the Biocor PSB xenograft a valid long-term therapy for the elderly. No-React treatment does not influence xenograft durability.

Uterine artery embolization for treatment of leiomyomata: long-term outcomes from the FIBROID Registry.

PubMed

Goodwin, Scott C; Spies, James B; Worthington-Kirsch, Robert; Peterson, Eric; Pron, Gaylene; Li, Shuang; Myers, Evan R

2008-01-01

To assess long-term clinical outcomes of uterine artery embolization across a wide variety of practice settings in a large patient cohort. The Fibroid Registry for Outcomes Data (FIBROID) for Uterine Embolization was a 3-year, single-arm, prospective, multi-center longitudinal study of the short- and long-term outcomes of uterine artery embolization for leiomyomata. Two thousand one hundred twelve patients with symptomatic leiomyomata were eligible for long-term follow-up at 27 sites representing a geographically diverse set of practices, including academic centers, community hospitals, and closed-panel health maintenance organizations. At 36 months after treatment, 1,916 patients remained in the study, and of these, 1,278 patients completed the survey. The primary measures of outcome were the symptom and health-related quality-of-life scores from the Uterine Fibroid Symptom and Quality of Life questionnaire. Mean symptom scores improved 41.41 points (P<.001), and the quality of life scores improved 41.47 points (P<.001), both moving into the normal range for this questionnaire. The improvements were independent of practice setting. During the 3 years of the study, Kaplan-Meier estimates of hysterectomy, myomectomy, or repeat uterine artery embolization were 9.79%, 2.82%, and 1.83% of the patients, respectively. Uterine artery embolization results in a durable improvement in quality of life. These results are achievable when the procedure is performed in any experienced community or academic interventional radiology practice. III.

Identifying Stem-like Cells Using Mitochondrial Membrane Potential | Center for Cancer Research

Cancer.gov

Therapies that are based on living cells promise to improve treatments for metastatic cancer and for many degenerative diseases. Lasting treatment of these maladies may require the durable persistence of cells. Long-term engraftment of cells – for months or years – and the generation of large numbers of progeny are characteristics of stem cells. Most approaches to isolate viable hematopoetic stem cells and therapeutically active T cells are based on immunophenotyping using highly multicolored flow cytometry. However, these methods do not directly measure the metabolic features of cells, which are known to be important in predicting cell fate.

Residual-strength tests of L-1011 vertical fin components after 10 and 20 years of simulated flight service

NASA Technical Reports Server (NTRS)

Lopez, O. F.

1984-01-01

Part of the NASA/ACEE Program was to determine the effect of long-term durability testing on the residual strength of graphite-epoxy cover panel and spar components of the Lockheed L-1011 aircraft vertical stabilizer. The results of these residual strength tests are presented herein. The structural behavior and failure mode of both cover panel and spar components were addressed, and the test results obtained were compared with the static test results generated by Lockheed. The effect of damage on one of the spar specimens was described.

Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

2014-01-01

This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

Durability Improvement of Pt/RGO Catalysts for PEMFC by Low-Temperature Self-Catalyzed Reduction.

PubMed

Sun, Kang Gyu; Chung, Jin Suk; Hur, Seung Hyun

2015-12-01

Pt/C catalyst used for polymer electrolyte membrane fuel cells (PEMFCs) displays excellent initial performance, but it does not last long because of the lack of durability. In this study, a Pt/reduced graphene oxide (RGO) catalyst was synthesized by the polyol method using ethylene glycol (EG) as the reducing agent, and then low-temperature hydrogen bubbling (LTHB) treatment was introduced to enhance the durability of the Pt/RGO catalyst. The cyclic voltammetry (CV), oxygen reduction reaction (ORR) analysis, and transmittance electron microscopy (TEM) results suggested that the loss of the oxygen functional groups, because of the hydrogen spillover and self-catalyzed dehydration reaction during LTHB, reduced the carbon corrosion and Pt agglomeration and thus enhanced the durability of the electrocatalyst.

Space life support engineering program

NASA Technical Reports Server (NTRS)

Seagrave, Richard C.

1991-01-01

This report covers the first six months of work performed under the NASA University Grant awarded to Iowa State University to perform research on two topics relating to the development of closed-loop long-term life support systems. A comprehensive study to develop software to simulate the dynamic operation of water reclamation systems in long-term closed-loop life support systems is being carried out as part of an overall program for the design of systems for a Mars voyage. This project is being done in parallel with a similar effort in the Department of Chemistry to develop durable accurate low-cost sensors for monitoring of trace chemical and biological species in recycled water supplies. Aspen-Plus software is being used on a group of high-performance workstations to develop the steady state descriptions for a number of existing technologies. Following completion, a dynamic simulation package will be developed for determining the response of such systems to changes in the metabolic needs of the crew and to upsets in system hardware performance.

Vascular Access Tracking System: a Web-Based Clinical Tracking Tool for Identifying Catheter Related Blood Stream Infections in Interventional Radiology Placed Central Venous Catheters.

PubMed

Morrison, James; Kaufman, John

2016-12-01

Vascular access is invaluable in the treatment of hospitalized patients. Central venous catheters provide a durable and long-term solution while saving patients from repeated needle sticks for peripheral IVs and blood draws. The initial catheter placement procedure and long-term catheter usage place patients at risk for infection. The goal of this project was to develop a system to track and evaluate central line-associated blood stream infections related to interventional radiology placement of central venous catheters. A customized web-based clinical database was developed via open-source tools to provide a dashboard for data mining and analysis of the catheter placement and infection information. Preliminary results were gathered over a 4-month period confirming the utility of the system. The tools and methodology employed to develop the vascular access tracking system could be easily tailored to other clinical scenarios to assist in quality control and improvement programs.

Ruxolitinib: long-term management of patients with myelofibrosis and future directions in the treatment of myeloproliferative neoplasms.

PubMed

Yacoub, A; Odenike, O; Verstovsek, S

2014-12-01

Considerable clinical experience regarding the long-term efficacy and safety of ruxolitinib has been gathered since the drug was approved in the USA for patients with intermediate or high-risk myelofibrosis (MF) in November 2011. Findings from the pivotal phase 3 COMFORT studies showed that ruxolitinib-associated reductions in MF-related splenomegaly and symptom burden occur rapidly and in the majority of patients. Two- and 3-year follow-up data further suggest that the benefits of ruxolitinib are durable and associated with a survival advantage compared with conventional therapies. However, careful management of treatment-related thrombocytopenia and anemia with dose modifications and supportive care is critical to allow chronic therapy. Based on preliminary evidence, ruxolitinib also allows spleen size and symptom reduction before allogeneic stem cell transplantation without negative effect on engraftment or outcomes. In recent studies, ruxolitinib provided effective management of hematologic parameters and symptoms in patients with polycythemia vera refractory to or intolerant of hydroxyurea.

Honeycomb-like Porous Carbon-Cobalt Oxide Nanocomposite for High-Performance Enzymeless Glucose Sensor and Supercapacitor Applications.

PubMed

Madhu, Rajesh; Veeramani, Vediyappan; Chen, Shen-Ming; Manikandan, Arumugam; Lo, An-Ya; Chueh, Yu-Lun

2015-07-29

Herein, we report the preparation of Pongam seed shells-derived activated carbon and cobalt oxide (∼2-10 nm) nanocomposite (PSAC/Co3O4) by using a general and facile synthesis strategy. The as-synthesized PSAC/Co3O4 samples were characterized by a variety of physicochemical techniques. The PSAC/Co3O4-modified electrode is employed in two different applications such as high performance nonenzymatic glucose sensor and supercapacitor. Remarkably, the fabricated glucose sensor is exhibited an ultrahigh sensitivity of 34.2 mA mM(-1) cm(-2) with a very low detection limit (21 nM) and long-term durability. The PSAC/Co3O4 modified stainless steel electrode possesses an appreciable specific capacitance and remarkable long-term cycling stability. The obtained results suggest the as-synthesized PSAC/Co3O4 is more suitable for the nonenzymatic glucose sensor and supercapacitor applications outperforming the related carbon based modified electrodes, rendering practical industrial applications.

Patients with myeloid malignancies bearing PDGFRB fusion genes achieve durable long-term remissions with imatinib

PubMed Central

Cheah, Chan Y.; Burbury, Kate; Apperley, Jane F.; Huguet, Francoise; Pitini, Vincenzo; Gardembas, Martine; Ross, David M.; Forrest, Donna; Genet, Philippe; Rousselot, Philippe; Patton, Nigel; Smith, Graeme; Dunbar, Cynthia E.; Ito, Sawa; Aguiar, Ricardo C. T.; Odenike, Olatoyosi; Gimelfarb, Alla; Cross, Nicholas C. P.; Seymour, John F.

2014-01-01

Myeloid neoplasms and eosinophilia with rearrangements of PDGFRB are uncommon Philadelphia-negative myeloproliferative neoplasms. Patients are typically male, with morphologic features of a Philadelphia-negative chronic myeloproliferative syndrome or chronic myelomonocytic leukemia with eosinophilia. Reciprocal translocations involving PDGFRB result in fusion genes with constitutively activated receptor tyrosine kinase sensitive to inhibition with imatinib. We present an updated and expanded analysis of a cohort of 26 such patients treated with imatinib. After a median follow-up of 10.2 years (range, 1.8-17 years), the 10-year overall survival rate was 90% (95% confidence interval, 64%-97%); after median imatinib duration of 6.6 years (range, 0.1-12 years), the 6-year progression-free survival rate was 88% (95% confidence interval, 65%-96%). Of the patients, 96% responded; no patients who achieved a complete cytogenetic (n = 13) or molecular (n = 8) remission lost their response or progressed to blast crisis. Imatinib is well-tolerated and achieves excellent long-term responses in patients with PDGFRB rearrangements. PMID:24687085

An evaluation of the generalization and maintenance of functional communication and self-control skills with preschoolers.

PubMed

Luczynski, Kevin C; Hanley, Gregory P; Rodriguez, Nicole M

2014-01-01

The preschool life skills (PLS) program (Hanley, Heal, Tiger, & Ingvarsson, 2007; Luczynski & Hanley, 2013) involves teaching social skills as a means of decreasing and preventing problem behavior. However, achieving durable outcomes as children transition across educational settings depend on the generalization and long-term maintenance of those skills. The purpose of this study was to evaluate procedures for promoting generalization and long-term maintenance of functional communication and self-control skills for 6 preschool children. When the children's social skills decreased across repeated observations during a generalization assessment, we incorporated modifications to the teaching procedures. However, the effects of the modifications were variable across skills and children. Satisfactory generalization was observed only after the teacher was informed of the target skills and teaching strategies. Maintenance of most social skills was observed 3 months after teaching was discontinued. We discuss the importance of improving child and teacher behavior to promote generalization and maintenance of important social skills. © Society for the Experimental Analysis of Behavior.

Roux-en-Y Gastric Bypass and Vertical Banded Gastroplasty Induce Long-Term Changes on the Human Gut Microbiome Contributing to Fat Mass Regulation

PubMed Central

Tremaroli, Valentina; Karlsson, Fredrik; Werling, Malin; Ståhlman, Marcus; Kovatcheva-Datchary, Petia; Olbers, Torsten; Fändriks, Lars; le Roux, Carel W.; Nielsen, Jens; Bäckhed, Fredrik

2015-01-01

Summary Bariatric surgery is currently the most effective procedure for the treatment of obesity. Given the role of the gut microbiota in regulating host metabolism and adiposity, we investigated the long-term effects of bariatric surgery on the microbiome of patients randomized to Roux-en-Y gastric bypass or vertical banded gastroplasty and matched for weight and fat mass loss. The two surgical procedures induced similar and durable changes on the gut microbiome that were not dependent on body mass index and resulted in altered levels of fecal and circulating metabolites compared with obese controls. By colonizing germ-free mice with stools from the patients, we demonstrated that the surgically altered microbiota promoted reduced fat deposition in recipient mice. These mice also had a lower respiratory quotient, indicating decreased utilization of carbohydrates as fuel. Our results suggest that the gut microbiota may play a direct role in the reduction of adiposity observed after bariatric surgery. PMID:26244932

Flight service evaluation of composite helicopter components

NASA Technical Reports Server (NTRS)

Mardoian, George H.; Ezzo, Maureen B.

1994-01-01

This paper presents the results of a NASA funded contract and Sikorsky research and development programs to evaluate structural composite components in flight service on Sikorsky Model S-76 helicopters. Selected components were removed and tested at prescribed intervals over a nine year time frame. Four horizontal stabilizers and thirteen tail rotor spars were returned from commercial service in West Palm Beach, Florida and in the Gulf Coast region of Louisiana to determine the long term effects of operations in hot and humid climates on component performance. Concurrent with the flight component evaluation, panels of materials used in their fabrication were exposed to the environment in ground racks. Selected panels were tested annually to determine the effects of exposure on physical and mechanical properties. The results of 55,741 component flight hours and 911 months of field exposure are reported and compared with initial Federal Aviation Administration (FAA) certification data. The findings of this program have provided increased confidence in the long term durability of advanced composite materials used in helicopter structural applications.

In search of durable positive psychology interventions: Predictors and consequences of long-term positive behavior change

PubMed Central

Cohn, Michael A.; Fredrickson, Barbara L.

2011-01-01

A number of positive psychology interventions have successfully helped people learn skills for improving mood and building personal resources (e.g., psychological resilience and social support). However, little is known about whether intervention activities remain effective in the long term, or whether new resources are maintained after the intervention ends. We address these issues in a 15-month follow-up survey of participants from a loving-kindness meditation intervention. Many participants continued to practice meditation, and they reported more positive emotions (PEs) than those who had stopped meditating or had never meditated. All participants maintained gains in resources made during the initial intervention, whether or not they continued meditating. Continuing meditators did not differ on resources at baseline, but they did show more PE and a more rapid PE response to the intervention. Overall, our results suggest that positive psychology interventions are not just efficacious but of significant value in participants' real lives. PMID:21709728

Origins of house mice in ecological niches created by settled hunter-gatherers in the Levant 15,000 y ago

PubMed Central

Weissbrod, Lior; Marshall, Fiona B.; Valla, François R.; Khalaily, Hamoudi; Bar-Oz, Guy; Auffray, Jean-Christophe; Vigne, Jean-Denis; Cucchi, Thomas

2017-01-01

Reductions in hunter-gatherer mobility during the Late Pleistocene influenced settlement ecologies, altered human relations with animal communities, and played a pivotal role in domestication. The influence of variability in human mobility on selection dynamics and ecological interactions in human settlements has not been extensively explored, however. This study of mice in modern African villages and changing mice molar shapes in a 200,000-y-long sequence from the Levant demonstrates competitive advantages for commensal mice in long-term settlements. Mice from African pastoral households provide a referential model for habitat partitioning among mice taxa in settlements of varying durations. The data reveal the earliest known commensal niche for house mice in long-term forager settlements 15,000 y ago. Competitive dynamics and the presence and abundance of mice continued to fluctuate with human mobility through the terminal Pleistocene. At the Natufian site of Ain Mallaha, house mice displaced less commensal wild mice during periods of heavy occupational pressure but were outcompeted when mobility increased. Changing food webs and ecological dynamics in long-term settlements allowed house mice to establish durable commensal populations that expanded with human societies. This study demonstrates the changing magnitude of cultural niche construction with varying human mobility and the extent of environmental influence before the advent of farming. PMID:28348225

Origins of house mice in ecological niches created by settled hunter-gatherers in the Levant 15,000 y ago.

PubMed

Weissbrod, Lior; Marshall, Fiona B; Valla, François R; Khalaily, Hamoudi; Bar-Oz, Guy; Auffray, Jean-Christophe; Vigne, Jean-Denis; Cucchi, Thomas

2017-04-18

Reductions in hunter-gatherer mobility during the Late Pleistocene influenced settlement ecologies, altered human relations with animal communities, and played a pivotal role in domestication. The influence of variability in human mobility on selection dynamics and ecological interactions in human settlements has not been extensively explored, however. This study of mice in modern African villages and changing mice molar shapes in a 200,000-y-long sequence from the Levant demonstrates competitive advantages for commensal mice in long-term settlements. Mice from African pastoral households provide a referential model for habitat partitioning among mice taxa in settlements of varying durations. The data reveal the earliest known commensal niche for house mice in long-term forager settlements 15,000 y ago. Competitive dynamics and the presence and abundance of mice continued to fluctuate with human mobility through the terminal Pleistocene. At the Natufian site of Ain Mallaha, house mice displaced less commensal wild mice during periods of heavy occupational pressure but were outcompeted when mobility increased. Changing food webs and ecological dynamics in long-term settlements allowed house mice to establish durable commensal populations that expanded with human societies. This study demonstrates the changing magnitude of cultural niche construction with varying human mobility and the extent of environmental influence before the advent of farming.

Rate My Stake: Interpretation of Ordinal Stake Ratings

Treesearch

Patricia Lebow; Grant Kirker

2014-01-01

Ordinal rating systems are commonly employed to evaluate biodeterioration of wood exposed outdoors over long periods of time. The purpose of these ratings is to compare the durability of test systems to nondurable wood products or known durable wood products. There are many reasons why these systems have evolved as the chosen method of evaluation, including having an...

Long-term performance of the Hancock bioprosthetic valved conduit in the aortic root position.

PubMed

Badiu, Catalin C; Bleiziffer, Sabine; Eichinger, Walter B; Hettich, Ina; Krane, Markus; Bauernschmitt, Robert; Lange, Rüdiger

2011-03-01

The study aim was to assess long-term morbidity and mortality with special regard to prosthesis durability after aortic root replacement with the Hancock bioprosthetic porcine conduit. Between 1975 and 2004, a total of 81 patients (55 males, 26 females; mean age 58 +/- 18 years) underwent aortic root replacement with the Hancock conduit for aortic dissection (n = 22; 27%), ascending aortic aneurysm (n = 57; 70%), or porcelain aorta (n = 2; 3%). Twenty-five patients (31%) underwent an emergency operation, 12 (15%) presented with Marfan syndrome, and eight (10%) had undergone previous cardiac surgery. Concomitant procedures were performed in 26 cases (32%). The follow up was 98% complete; the mean follow up was 4.8 +/- 4.0 years (range: 1 day to 16.7 years), and the cumulative follow up was 403 patient-years. Actuarial event-free rates were calculated, and valve-related complications classified according to guidelines for reporting morbidity and mortality after cardiac valvular operations. There were seven (9%) operative deaths and four (5%) in-hospital deaths. Actuarial survival rates at five and 10 years (excluding operative deaths) were 77.0 +/- 5.3% and 54.0 +/- 7.5%, respectively. Actuarial freedom from aortic valve reoperation at five and 10 years was 98 +/- 1.6% and 64 +/- 10.2%, from structural valve deterioration 88.1 +/- 4.7% and 49.9 +/- 9.6%, from thromboembolic events 87.4 +/- 4.6% and 75.1 +/- 9.5%, and from major bleeding events 90.2 +/- 3.9% and 75.4 +/- 8.1%, respectively. Among redo procedures, the stentless Hancock valve could be excised without separating the synthetic graft from the left ventricular outflow tract, and a stented valve prosthesis thus implanted. Hence, it was possible to avoid a second Bentall operation. The long-term survival rates after aortic root replacement with the bioprosthetic Hancock conduit were reasonable for this demanding patient cohort. However, the durability of the prosthesis was inferior to that reported for the stented Hancock valve substitute. The key benefit of this bioprosthetic valved conduit was the simplified redo procedure.

Chemically stable and mechanically durable superamphiphobic aluminum surface with a micro/nanoscale binary structure.

PubMed

Peng, Shan; Yang, Xiaojun; Tian, Dong; Deng, Wenli

2014-09-10

We developed a simple fabrication method to prepare a superamphiphobic aluminum surface. On the basis of a low-energy surface and the combination of micro- and nanoscale roughness, the resultant surface became super-repellent toward a wide range of liquids with surface tensions of 25.3-72.1 mN m(-1). The applied approach involved (1) the formation of an irregular microplateau structure on an aluminum surface, (2) the fabrication of a nanoplatelet structure, and (3) fluorination treatment. The chemical stability and mechanical durability of the superamphiphobic surface were evaluated in detail. The results demonstrated that the surface presented an excellent chemical stability toward cool corrosive liquids (HCl/NaOH solutions, 25 °C) and 98% concentrated sulfuric acid, hot liquids (water, HCl/NaOH solutions, 30-100 °C), solvent immersion, high temperature, and a long-term period. More importantly, the surface also exhibited robust mechanical durability and could withstand multiple-fold, finger-touch, intensive scratching by a sharp blade, ultrasonication treatment, boiling treatment in water and coffee, repeated peeling by adhesive tape, and even multiple abrasion tests under 500 g of force without losing superamphiphobicity. The as-prepared superamphiphobic surface was also demonstrated to have excellent corrosion resistance. This work provides a simple, cost-effective, and highly efficient method to fabricate a chemically stable and mechanically robust superamphiphobic aluminum surface, which can find important outdoor applications.

Long-term effects of interference on short-term memory performance in the rat

PubMed Central

Missaire, Mégane; Fraize, Nicolas; Joseph, Mickaël Antoine; Hamieh, Al Mahdy; Parmentier, Régis; Marighetto, Aline; Salin, Paul Antoine; Malleret, Gaël

2017-01-01

A distinction has always been made between long-term and short-term memory (also now called working memory, WM). The obvious difference between these two kinds of memory concerns the duration of information storage: information is supposedly transiently stored in WM while it is considered durably consolidated into long-term memory. It is well acknowledged that the content of WM is erased and reset after a short time, to prevent irrelevant information from proactively interfering with newly stored information. In the present study, we used typical WM radial maze tasks to question the brief lifespan of spatial WM content in rodents. Groups of rats were submitted to one of two different WM tasks in a radial maze: a WM task involving the repetitive presentation of a same pair of arms expected to induce a high level of proactive interference (PI) (HIWM task), or a task using a different pair in each trial expected to induce a low level of PI (LIWM task). Performance was effectively lower in the HIWM group than in LIWM in the final trial of each training session, indicative of a “within-session/short-term” PI effect. However, we also observed a different “between-session/long-term” PI effect between the two groups: while performance of LIWM trained rats remained stable over days, the performance of HIWM rats dropped after 10 days of training, and this impairment was visible from the very first trial of the day, hence not attributable to within-session PI. We also showed that a 24 hour-gap across training sessions known to allow consolidation processes to unfold, was a necessary and sufficient condition for the long-term PI effect to occur. These findings suggest that in the HIWM task, WM content was not entirely reset between training sessions and that, in specific conditions, WM content can outlast its purpose by being stored more permanently, generating a long-term deleterious effect of PI. The alternative explanation is that WM content could be transferred and stored more permanently in an intermediary form or memory between WM and long-term memory. PMID:28288205

Functional Analysis in Long-Term Operation of High Power UV-LEDs in Continuous Fluoro-Sensing Systems for Hydrocarbon Pollution

PubMed Central

Arques-Orobon, Francisco Jose; Nuñez, Neftali; Vazquez, Manuel; Gonzalez-Posadas, Vicente

2016-01-01

This work analyzes the long-term functionality of HP (High-power) UV-LEDs (Ultraviolet Light Emitting Diodes) as the exciting light source in non-contact, continuous 24/7 real-time fluoro-sensing pollutant identification in inland water. Fluorescence is an effective alternative in the detection and identification of hydrocarbons. The HP UV-LEDs are more advantageous than classical light sources (xenon and mercury lamps) and helps in the development of a low cost, non-contact, and compact system for continuous real-time fieldwork. This work analyzes the wavelength, output optical power, and the effects of viscosity, temperature of the water pollutants, and the functional consistency for long-term HP UV-LED working operation. To accomplish the latter, an analysis of the influence of two types 365 nm HP UV-LEDs degradation under two continuous real-system working mode conditions was done, by temperature Accelerated Life Tests (ALTs). These tests estimate the mean life under continuous working conditions of 6200 h and for cycled working conditions (30 s ON & 30 s OFF) of 66,000 h, over 7 years of 24/7 operating life of hydrocarbon pollution monitoring. In addition, the durability in the face of the internal and external parameter system variations is evaluated. PMID:26927113

High-Fidelity Visual Long-Term Memory within an Unattended Blink of an Eye.

PubMed

Kuhbandner, Christof; Rosas-Corona, Elizabeth A; Spachtholz, Philipp

2017-01-01

What is stored in long-term memory from current sensations is a question that has attracted considerable interest. Over time, several prominent theories have consistently proposed that only attended sensory information leaves a durable memory trace whereas unattended information is not stored beyond the current moment, an assumption that seems to be supported by abundant empirical evidence. Here we show, by using a more sensitive memory test than in previous studies, that this is actually not true. Observers viewed a rapid stream of real-world object pictures overlapped by words (presentation duration per stimulus: 500 ms, interstimulus interval: 200 ms), with the instruction to attend to the words and detect word repetitions, without knowing that their memory would be tested later. In a surprise two-alternative forced-choice recognition test, memory for the unattended object pictures was tested. Memory performance was substantially above chance, even when detailed feature knowledge was necessary for correct recognition, even when tested 24 h later, and even although participants reported that they do not have any memories. These findings suggests that humans have the ability to store at high speed detailed copies of current visual stimulations in long-term memory independently of current intentions and the current attentional focus.

Current status in the treatment options for esophageal achalasia

PubMed Central

Chuah, Seng-Kee; Chiu, Chien-Hua; Tai, Wei-Chen; Lee, Jyong-Hong; Lu, Hung-I; Changchien, Chi-Sin; Tseng, Ping-Huei; Wu, Keng-Liang

2013-01-01

Recent advances in the treatment of achalasia include the use of high-resolution manometry to predict the outcome of patients and the introduction of peroral endoscopic myotomy (POEM). The first multicenter randomized, controlled, 2-year follow-up study conducted by the European Achalasia Trial group indicated that laparoscopic Heller myotomy (LHM) was not superior to pneumatic dilations (PD). Publications on the long-term success of laparoscopic surgery continue to emerge. In addition, laparoscopic single-site surgery is applicable to advanced laparoscopic operations such as LHM and anterior fundoplication. The optimal treatment option is an ongoing matter of debate. In this review, we provide an update of the current progress in the treatment of esophageal achalasia. Unless new conclusive data prove otherwise, LHM is considered the most durable treatment for achalasia at the expense of increased reflux-associated complications. However, PD is the first choice for non-surgical treatment and is more cost-effective. Repeated PD according to an “on-demand” strategy based on symptom recurrence can achieve long-term remission. Decision making should be based on clinical evidence that identifies a subcategory of patients who would benefit from specific treatment options. POEM has shown promise but its long-term efficacy and safety need to be assessed further. PMID:24023484

Current status in the treatment options for esophageal achalasia.

PubMed

Chuah, Seng-Kee; Chiu, Chien-Hua; Tai, Wei-Chen; Lee, Jyong-Hong; Lu, Hung-I; Changchien, Chi-Sin; Tseng, Ping-Huei; Wu, Keng-Liang

2013-09-07

Recent advances in the treatment of achalasia include the use of high-resolution manometry to predict the outcome of patients and the introduction of peroral endoscopic myotomy (POEM). The first multicenter randomized, controlled, 2-year follow-up study conducted by the European Achalasia Trial group indicated that laparoscopic Heller myotomy (LHM) was not superior to pneumatic dilations (PD). Publications on the long-term success of laparoscopic surgery continue to emerge. In addition, laparoscopic single-site surgery is applicable to advanced laparoscopic operations such as LHM and anterior fundoplication. The optimal treatment option is an ongoing matter of debate. In this review, we provide an update of the current progress in the treatment of esophageal achalasia. Unless new conclusive data prove otherwise, LHM is considered the most durable treatment for achalasia at the expense of increased reflux-associated complications. However, PD is the first choice for non-surgical treatment and is more cost-effective. Repeated PD according to an "on-demand" strategy based on symptom recurrence can achieve long-term remission. Decision making should be based on clinical evidence that identifies a subcategory of patients who would benefit from specific treatment options. POEM has shown promise but its long-term efficacy and safety need to be assessed further.

Renal Angiomyolipoma: Mid- to Long-Term Results Following Embolization with Onyx

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thulasidasan, Narayanan, E-mail: narayanant@doctors.net.uk; Sriskandakumar, Srividhiya; Ilyas, Shahzad

PurposePercutaneous transcatheter embolization is currently the preferred treatment for ruptured or enlarging renal angiomyolipoma (AML), although the optimum choice of embolic material has not yet been established. We present mid- to long-term outcomes following embolization of AMLs with Onyx.Materials and MethodsTen AMLs in seven patients (including two with tuberous sclerosis) were embolized with Onyx. Patients were followed-up clinically, with tumour size and renal function measured pre- and post-procedure.ResultsMean pre-treatment AML size was 63.4 mm (range 42–100). Mean clinical follow-up was 431.4 days (range 153–986) and imaging follow-up 284.2 days (range 30–741). There was no haemorrhage from treated lesions within the follow-up period. Ofmore » patients who had cross-sectional imaging pre- and post-procedure, mean decrease in AML size of 22 mm was seen after Onyx embolization (p = 0.0058, 95 % CI 9.13–34.87). No significant difference between serum creatinine was seen pre- and post-procedure (p = 0.54, 95 % CI 8.63–4.85).ConclusionsOnyx embolization of renal AMLs is effective in the medium to long term, with theoretical benefits in safety and durability of result.« less

Opportunities and challenges for the biodegradable magnesium alloys as next-generation biomaterials

PubMed Central

Ding, Wenjiang

2016-01-01

In recent years, biodegradable magnesium alloys emerge as a new class of biomaterials for tissue engineering and medical devices. Deploying biodegradable magnesium-based materials not only avoids a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials are often subjected to an uncontrolled and fast degradation, acute toxic responses and rapid structural failure presumably due to a localized, too rapid corrosion process. The patented Mg–Nd–Zn–based alloys (JiaoDa BioMg [JDBM]) have been developed in Shanghai Jiao Tong University in recent years. The alloy series exhibit lower biodegradation rate and homogeneous nanophasic degradation patterns as compared with other biodegradable Mg alloys. The in vitro cytotoxicity tests using various types of cells indicate excellent biocompatibility of JDBM. Finally, bone implants using JDBM-1 alloy and cardiovascular stents using JDBM-2 alloy have been successfully fabricated and in vivo long-term assessment via implantation in animal model have been performed. The results confirmed the reduced degradation rate in vivo, excellent tissue compatibility and long-term structural and mechanical durability. Thus, this novel Mg-alloy series with highly uniform nanophasic biodegradation represent a major breakthrough in the field and a promising candidate for manufacturing the next generation biodegradable implants. PMID:27047673

An evaluation of controlled permeability formwork for long-term durability of structural concrete elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suryavanshi, A.K.; Swamy, R.N.

1997-07-01

The long-term performance of a concrete slab (CPF slab) exposed to chloride ingress and atmospheric carbonation from the surface generated by controlled permeability formwork (CPF) is investigated. The results are compared with a similar slab exposed to long-term chloride ingress and atmospheric carbonation from the cast face (Control slab). Techniques such as X-ray diffraction (XRD) and differential thermal analyses (DTA) were employed to determine the resistance against carbonation while, mercury porosimetry was used for investigating the pore size distribution at the surface of the slabs. Amount of acid soluble chlorides was determined by using Volhard`s method. The CPF employed atmore » the bottom of the mould was not fully effective in its intended purpose of generating a permanent and dense impermeable concrete layer adjacent to it when the design water-cement (w/c) ration of the concrete mix was 0.60. This resulted in an almost similar extent of carbonation at the surface for both CPF and control slabs as shown by XRD and DTA studies. Similarly, there were no significant differences in the amount of chlorides and their depths of penetration for both CPF and control slabs, although the former was marginally superior in chloride penetration resistance at the surface.« less

Long-term prospective evaluation of an inpatient voiding reeducation program for lower urinary tract conditions in children.

PubMed

Golli, Tanja; Meglič, Anamarija; Kenda, Rajko B

2013-04-01

Our aim was to evaluate the efficacy of our treatment program for children with lower urinary tract conditions, developed at the Department of Pediatric Nephrology of the University Children's Hospital in Ljubljana. Sixty-four patients with lower urinary tract conditions were randomly allocated to two groups. Group A received treatment immediately, whereas patients of group B received no treatment for a period of 3 months-the amount of time it takes to complete our program. No child in group B experienced spontaneous regression of their symptoms in the 3-month delay period, while the patients of group A were already being treated and were achieving results. Thus, all the patients of group B then entered the program in exactly the same way as patients of group A. The final success rate in both groups did not differ significantly (p = 0.706-1.000) and ranged from 86.2 % for group A and 86.7 to 90 % for group B. Long-term follow-up showed statistically identical success rates (p = 1.000). This prospective controlled study with long-term follow-up (48 months) shows that our treatment program, applied as an inpatient voiding school program, is an effective method, with durable results.

Functional Analysis in Long-Term Operation of High Power UV-LEDs in Continuous Fluoro-Sensing Systems for Hydrocarbon Pollution.

PubMed

Arques-Orobon, Francisco Jose; Nuñez, Neftali; Vazquez, Manuel; Gonzalez-Posadas, Vicente

2016-02-26

This work analyzes the long-term functionality of HP (High-power) UV-LEDs (Ultraviolet Light Emitting Diodes) as the exciting light source in non-contact, continuous 24/7 real-time fluoro-sensing pollutant identification in inland water. Fluorescence is an effective alternative in the detection and identification of hydrocarbons. The HP UV-LEDs are more advantageous than classical light sources (xenon and mercury lamps) and helps in the development of a low cost, non-contact, and compact system for continuous real-time fieldwork. This work analyzes the wavelength, output optical power, and the effects of viscosity, temperature of the water pollutants, and the functional consistency for long-term HP UV-LED working operation. To accomplish the latter, an analysis of the influence of two types 365 nm HP UV-LEDs degradation under two continuous real-system working mode conditions was done, by temperature Accelerated Life Tests (ALTs). These tests estimate the mean life under continuous working conditions of 6200 h and for cycled working conditions (30 s ON & 30 s OFF) of 66,000 h, over 7 years of 24/7 operating life of hydrocarbon pollution monitoring. In addition, the durability in the face of the internal and external parameter system variations is evaluated.

Bronchial Thermoplasty – Long Term Safety and Effectiveness in Severe Persistent Asthma

PubMed Central

Wechsler, Michael E.; Laviolette, Michel; Rubin, Adalberto S.; Fiterman, Jussara; Lapa e Silva, Jose R.; Shah, Pallav L.; Fiss, Elie; Olivenstein, Ronald; Thomson, Neil C.; Niven, Robert M.; Pavord, Ian D.; Simoff, Michael; Hales, Jeff B.; McEvoy, Charlene; Slebos, Dirk-Jan; Holmes, Mark; Phillips, Martin J.; Erzurum, Serpil C.; Hanania, Nicola A.; Sumino, Kaharu; Kraft, Monica; Cox, Gerard; Sterman, Daniel H.; Hogarth, Kyle; Kline, Joel N.; Mansur, Adel H.; Louie, Brian E.; Leeds, William M.; Barbers, Richard G.; Austin, John H.M.; Shargill, Narinder S.; Quiring, John; Armstrong, Brian; Castro, Mario

2014-01-01

Background Bronchial thermoplasty (BT) has previously been shown to improve asthma control out to 2 years in patients with severe persistent asthma. Objective To assess effectiveness and safety of BT in asthma patients 5 years post therapy. Methods BT-treated subjects from the Asthma Intervention Research 2 (AIR2) Trial (ClinicalTrials.gov NCT01350414) were evaluated annually for 5 years to assess long-term safety of BT and durability of treatment effect. Outcomes assessed post-BT included severe exacerbations, adverse events, healthcare utilization, spirometry data, and high resolution computed tomography (HRCT) scans. Results 162/190 BT-treated subjects (85.3%) from the AIR2 Trial completed 5 years of follow-up. The proportion of subjects experiencing severe exacerbations and Emergency Room visits, and the rates of events in each of years 1 to 5 remained low and were less than those observed in the 12 months prior to BT treatment (average 5 year reduction in proportions: 44% for exacerbations and 78% for ER visits). Respiratory adverse events and respiratory-related hospitalizations remained unchanged in Years 2 through 5 as compared to the first year after BT. Pre-BD FEV1 values remained stable between years 1 and 5 after BT, despite a 17% reduction in average daily inhaled corticosteroid dose. HRCT scans from baseline to 5 years after BT showed no structural abnormalities that could be attributed to BT. Conclusions These data demonstrate the 5-year durability of the benefits of BT with regard to both asthma control (based on maintained reduction in severe exacerbations and ER visits for respiratory symptoms) and safety. BT has become an important addition to our treatment armamentarium and should be considered for patients with severe persistent asthma who remain symptomatic despite taking ICS (inhaled corticosteroids) and LABA (long-acting-β2-agonists). PMID:23998657

Lower esophageal sphincter injections for the treatment of gastroesophageal reflux disease.

PubMed

Watson, Thomas J; Peters, Jeffrey H

2005-08-01

Endoscopic therapies for the control of GERD offer the potential for significant symptomatic improvement while obviating many of the potential drawbacks associated with long-term medical therapy with acid suppressive or neutralizing medications and traditional antireflux surgery. Such endoluminal therapies are intended to be safe with a brief learning curve, easily administered in an outpatient setting without the need for general anesthesia, reproducible, and durable. LES injection therapies share the common theoretic method of action of bulking at the GEJ, leading to loss of sphincter compliance and distensibility. In the case of Enteryx, this sustained effect has been demonstrated to be secondary to chronic inflammation, fibrosis, and encapsulation resulting from a foreign body response to the injectate. Available data suggest that a majority of patients respond to LES injection therapies, as demonstrated by a decreasing usage of PPIs after implantation, the ability of many patients to terminate PPI use completely, and improved GERD-HRQOL scores. Responses seem reasonably durable in follow-up assessment up to 24 months post treatment. Although there may be some placebo effect associated with treatment, patients injected with Enteryx respond better than a control group of sham-treated subjects. Individuals treated with LES injections, however, represent a select subgroup of the overall population of refluxers. Study subjects, by and large, have had uncomplicated GERD with typical reflux symptoms of heartburn or regurgitation that have responded to PPIs. Patients who have severe anatomic derangements, such as esophageal strictures, persistent esophagitis, Barrett's esophagus, or sizeable hiatal hernias, are excluded from clinical trials, as are patients who have severe motility disorders or significant comorbid conditions. Similarly, patients who have responded poorly to PPIs and those who have primarily extraesophageal manifestations of GERD have not been studied. Outcomes to date have been assessed over the short to medium term; long-term outcome studies are lacking. The durability of response, therefore, remains largely unknown, as does the incidence of any long-term complications or side effects. A postmarket study to assess the long-term safety and durability of Enteryx therapy up to 36 months is under way, as required by the FDA, with a target enrollment of 300 patients. Detailed cost analyses have yet to be reported. Such data are important not only for comparing the various endoluminal therapies but also for comparison to standard medical therapy and antireflux surgery. At present, no randomized trials are completed that compare injection therapies to other accepted treatments of GERD. The ability to perform fundoplication safely and effectively after failed LES injection therapy is not well known, in that the number of subsequent surgical cases is small and the results largely anecdotal to date. Likewise, the ability to use LES injection as salvage therapy after failed fundoplication has not been tested. The data regarding endoluminal injection therapies are similar to those after endoscopic plication and radiofrequency application to the LES, in that a definite symptomatic response is observed, but the objective documentation of diminished esophageal acid exposure lags behind. Esophageal acid exposure is normalized in a minority of treated subjects and improved in an additional subgroup, whereas the rate of symptomatic response exceeds these objective improvements. The reasons for this disconnect are the subject of much speculation and controversy. A placebo effect has been discussed, but clearly more factors are at play. Perhaps a study effect also is important, in that patients enrolled in clinical trials for GERD control may be more likely to modify their dietary and lifestyle habits in an effort to bring about symptom relief. Maybe the understanding of the perception of reflux events is lacking, and these endoluminal therapies work mainly by altering the perception of reflux more than the amount of reflux itself. A recent technologic review of injection therapies for GERD concludes that the "data for Enteryx are as compelling as those of any other open-label evaluation of an endoluminal therapy for GERD". There is much to be learned about all endoluminal techniques. For now, LES injections are promising therapies lacking supportive evidence of long-term safety and efficacy. The available data justify their use only in patients who have GERD symptoms responsive to PPIs and who do not have significant comorbidities or complications associated with GERD. Whether or not the role of LES injection techniques will be expanded to include more complicated cases, patients who are partially responsive to PPIs, combination therapy with other endoluminal techniques, or salvage therapy after failed fundoplication awaits further study.

A green and bio-inspired process to afford durable anti-biofilm properties to stainless steel.

PubMed

Faure, E; Vreuls, C; Falentin-Daudré, C; Zocchi, G; Van de Weerdt, C; Martial, J; Jérôme, C; Duwez, A-S; Detrembleur, C

2012-01-01

A bio-inspired durable anti-biofilm coating was developed for industrial stainless steel (SS) surfaces. Two polymers inspired from the adhesive and cross-linking properties of mussels were designed and assembled from aqueous solutions onto SS surfaces to afford durable coatings. Trypsin, a commercially available broad spectrum serine protease, was grafted as the final active layer of the coating. Its proteolytic activity after long immersion periods was demonstrated against several substrata, viz. a synthetic molecule, N-α-benzoyl-DL-arginine-p-nitroanilide hydrochloride (BAPNA), a protein, FTC-casein, and Gram-positive biofilm forming bacterium Staphylococcus epidermidis.

Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

NASA Astrophysics Data System (ADS)

Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

2017-12-01

The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

Transcatheter aortic valve implantation: durability of clinical and hemodynamic outcomes beyond 3 years in a large patient cohort.

PubMed

Gurvitch, R; Wood, D A; Tay, E L; Leipsic, J; Ye, J; Lichtenstein, S V; Thompson, C R; Carere, R G; Wijesinghe, N; Nietlispach, F; Boone, R H; Lauck, S; Cheung, A; Webb, J G

2010-09-28

Although short- and medium-term outcomes after transcatheter aortic valve implantation are encouraging, long-term data on valve function and clinical outcomes are limited. Consecutive high-risk patients who had been declined as surgical candidates because of comorbidities but who underwent successful transcatheter aortic valve implantation with a balloon-expandable valve between January 2005 and December 2006 and survived past 30 days were assessed. Clinical, echocardiographic, and computed tomographic follow-up examinations were performed. Seventy patients who underwent successful procedures and survived longer than 30 days were evaluated at a minimum follow-up of 3 years. At a median follow-up of 3.7 years (interquartile range 3.4 to 4.3 years), survival was 57%. Survival at 1, 2, and 3 years was 81%, 74%, and 61%, respectively. Freedom from reoperation was 98.5% (1 patient with endocarditis). During this early procedural experience, 11 patients died within 30 days, and 8 procedures were unsuccessful. When these patients were included, overall survival was 51%. Transaortic pressure gradients increased from 10.0 mm Hg (interquartile range 8.0 to 12.0 mm Hg) immediately after the procedure to 12.1 mm Hg (interquartile range 8.6 to 16.0 mm Hg) after 3 years (P=0.03). Bioprosthetic valve area decreased from a mean of 1.7±0.4 cm(2) after the procedure to 1.4±0.3 cm(2) after 3 years (P<0.01). Aortic incompetence after implantation was trivial or mild in 84% of cases and remained unchanged or improved over time. There were no cases of structural valvular deterioration, stent fracture, deformation, or valve migration. Transcatheter aortic valve implantation demonstrates good medium- to long-term durability and preserved hemodynamic function, with no evidence of structural failure. The procedure appears to offer an adequate and lasting resolution of aortic stenosis in selected patients.

Spasmodic Dysphonia in Multiple Sclerosis Treatment With Botulin Toxin A: A Pilot Study.

PubMed

Di Stadio, Arianna; Bernitsas, Evanthia; Restivo, Domenico Antonio; Alfonsi, Enrico; Marchese-Ragona, Rosario

2018-04-09

This study aims to evaluate the effect of botulin toxin A in patients with multiple sclerosis (MS) affected by spasmodic dysphonia (SD) and to show the safety and effectiveness of this treatment in long-term observation. This is a pilot study on three relapsing-remitting MS patients with SD and their response to botulin toxin A. None of the patients reported dysphagia or other adverse events. Significant improvement was observed in terms of both voice quality and laryngostroboscopy results. The treatment effect was durable for 6-8 months. Botulin toxin A is a safe treatment that can be successfully used to treat SD in patients with MS. Larger studies are necessary to confirm our results. Copyright © 2018 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Force Required to Cinch the Tricuspid Annulus: An Ex-Vivo Study

PubMed Central

Adkins, Amy; Aleman, Jesus; Boies, Lori; Sako, Edward; Bhattacharya, Shamik

2016-01-01

Background and aim of the study Tricuspid annuloplasty is the most preferred technique for the treatment of functional tricuspid regurgitation (FTR). However, high incidences of recurrent regurgitation and risky reoperation demands a deeper insight into the technique. The cinching force required to bring a dilated annulus back to the original size is unknown. The study aim was to quantify the cinching force in the tricuspid annulus which can contribute to the long-term durability of tricuspid annuloplasty and percutaneous device design. Methods In ten ovine hearts, a suture was anchored around the free wall of the tricuspid annulus with the free end attached to a force transducer. The force transducer was mounted on a slider system which pulled the suture at regular intervals. Closure of the tricuspid valve was achieved by pressurizing the right ventricle at 30 mmHg through the pulmonary valve. The suture was pulled to cinch the tricuspid annulus. The tricuspid annulus area was measured from images taken at each increment, and the corresponding force was recorded. The hearts were tested for three conditions: (i) non-pressurized (NP); (ii) pressurized (P; normal), and (iii) dilated-pressurized (DP; diseased). Leakage data were also collected for pressurized and dilated pressurized conditions. Annulus dilation was created by injecting phenol into the annulus. Results The maximum annulus dilation obtained was 8.82%, and the maximum cinching force was 0.38 ± 0.09 N. Leakage was increased by 81.73% from the pressurized to dilated condition. Conclusion The minimal force required to cinch a tricuspid annulus with severe FTR (23.98% dilation) can be approximated to 0.25 N. The required cinching force can play a major role in the long-term durability of the tricuspid annuloplasty. PMID:26897846

Long-term control of recurrent or refractory viral infections after allogeneic HSCT with third-party virus-specific T cells.

PubMed

Withers, Barbara; Blyth, Emily; Clancy, Leighton E; Yong, Agnes; Fraser, Chris; Burgess, Jane; Simms, Renee; Brown, Rebecca; Kliman, David; Dubosq, Ming-Celine; Bishop, David; Sutrave, Gaurav; Ma, Chun Kei Kris; Shaw, Peter J; Micklethwaite, Kenneth P; Gottlieb, David J

2017-11-14

Donor-derived adoptive T-cell therapy is a safe and effective treatment of viral infection posttransplant, but it is limited by donor serostatus and availability and by its personalized nature. Off-the-shelf, third-party virus-specific T cells (VSTs) appear promising, but the long-term safety and durability of responses have yet to be established. We conducted a prospective study of 30 allogeneic hemopoietic stem cell transplant (HSCT) patients with persistent or recurrent cytomegalovirus (CMV) (n = 28), Epstein-Barr virus (n = 1), or adenovirus (n = 1) after standard therapy. Patients were treated with infusions of partially HLA-matched, third-party, ex vivo-expanded VSTs (total = 50 infusions) at a median of 75 days post-HSCT (range, 37 to 349 days). Safety, viral dynamics, and immune recovery were monitored for 12 months. Infusions were safe and well tolerated. Acute graft versus host disease occurred in 2 patients, despite a median HLA match between VSTs and the recipient of 2 of 6 antigens. At 12 months, the cumulative incidence of overall response was 93%. Virological control was durable in the majority of patients; the reintroduction of antiviral therapy after the final infusion occurred in 5 patients. CMV-specific T-cell immunity rose significantly and coincided with a rise in CD8 + terminal effector cells. PD-1 expression was elevated on CD8 + lymphocytes before the administration of third-party T cells and remained elevated at the time of viral control. Third-party VSTs show prolonged benefit, with virological control achieved in association with the recovery of CD8 + effector T cells possibly facilitated by VST infusion. This trial was registered at www.clinicaltrials.gov as #NCT02779439 and www.anzctr.org.au as #ACTRN12613000603718.

Long-term control of recurrent or refractory viral infections after allogeneic HSCT with third-party virus-specific T cells

PubMed Central

Withers, Barbara; Clancy, Leighton E.; Yong, Agnes; Fraser, Chris; Burgess, Jane; Simms, Renee; Brown, Rebecca; Kliman, David; Dubosq, Ming-Celine; Bishop, David; Sutrave, Gaurav; Ma, Chun Kei Kris; Shaw, Peter J.; Micklethwaite, Kenneth P.

2017-01-01

Donor-derived adoptive T-cell therapy is a safe and effective treatment of viral infection posttransplant, but it is limited by donor serostatus and availability and by its personalized nature. Off-the-shelf, third-party virus-specific T cells (VSTs) appear promising, but the long-term safety and durability of responses have yet to be established. We conducted a prospective study of 30 allogeneic hemopoietic stem cell transplant (HSCT) patients with persistent or recurrent cytomegalovirus (CMV) (n = 28), Epstein-Barr virus (n = 1), or adenovirus (n = 1) after standard therapy. Patients were treated with infusions of partially HLA-matched, third-party, ex vivo–expanded VSTs (total = 50 infusions) at a median of 75 days post-HSCT (range, 37 to 349 days). Safety, viral dynamics, and immune recovery were monitored for 12 months. Infusions were safe and well tolerated. Acute graft versus host disease occurred in 2 patients, despite a median HLA match between VSTs and the recipient of 2 of 6 antigens. At 12 months, the cumulative incidence of overall response was 93%. Virological control was durable in the majority of patients; the reintroduction of antiviral therapy after the final infusion occurred in 5 patients. CMV-specific T-cell immunity rose significantly and coincided with a rise in CD8+ terminal effector cells. PD-1 expression was elevated on CD8+ lymphocytes before the administration of third-party T cells and remained elevated at the time of viral control. Third-party VSTs show prolonged benefit, with virological control achieved in association with the recovery of CD8+ effector T cells possibly facilitated by VST infusion. This trial was registered at www.clinicaltrials.gov as #NCT02779439 and www.anzctr.org.au as #ACTRN12613000603718. PMID:29296867

Seismic Risk Assessment and Loss Estimation for Tbilisi City

NASA Astrophysics Data System (ADS)

Tsereteli, Nino; Alania, Victor; Varazanashvili, Otar; Gugeshashvili, Tengiz; Arabidze, Vakhtang; Arevadze, Nika; Tsereteli, Emili; Gaphrindashvili, Giorgi; Gventcadze, Alexander; Goguadze, Nino; Vephkhvadze, Sophio

2013-04-01

The proper assessment of seismic risk is of crucial importance for society protection and city sustainable economic development, as it is the essential part to seismic hazard reduction. Estimation of seismic risk and losses is complicated tasks. There is always knowledge deficiency on real seismic hazard, local site effects, inventory on elements at risk, infrastructure vulnerability, especially for developing countries. Lately great efforts was done in the frame of EMME (earthquake Model for Middle East Region) project, where in the work packages WP1, WP2 , WP3 and WP4 where improved gaps related to seismic hazard assessment and vulnerability analysis. Finely in the frame of work package wp5 "City Scenario" additional work to this direction and detail investigation of local site conditions, active fault (3D) beneath Tbilisi were done. For estimation economic losses the algorithm was prepared taking into account obtained inventory. The long term usage of building is very complex. It relates to the reliability and durability of buildings. The long term usage and durability of a building is determined by the concept of depreciation. Depreciation of an entire building is calculated by summing the products of individual construction unit' depreciation rates and the corresponding value of these units within the building. This method of calculation is based on an assumption that depreciation is proportional to the building's (constructions) useful life. We used this methodology to create a matrix, which provides a way to evaluate the depreciation rates of buildings with different type and construction period and to determine their corresponding value. Finally loss was estimated resulting from shaking 10%, 5% and 2% exceedance probability in 50 years. Loss resulting from scenario earthquake (earthquake with possible maximum magnitude) also where estimated.

Long-Term Durability of Bioprosthetic Aortic Valves: Implications From 12,569 Implants

PubMed Central

Johnston, Douglas R.; Soltesz, Edward G.; Vakil, Nakul; Rajeswaran, Jeevanantham; Roselli, Eric E.; Sabik, Joseph F.; Smedira, Nicholas G.; Svensson, Lars G.; Lytle, Bruce W.; Blackstone, Eugene H.

2016-01-01

Background Increased life expectancy and younger patients’ desire to avoid lifelong anticoagulation requires a better understanding of bioprosthetic valve failure. This study evaluates risk factors associated with explantation for structural valve deterioration (SVD) in a long-term series of Carpentier-Edwards PERIMOUNT aortic valves (AV). Methods From June 1982 to January 2011, 12,569 patients underwent AV replacement with Edwards Lifesciences Carpentier-Edwards PERIMOUNT stented bovine pericardial prostheses, models 2700PM (n = 310) or 2700 (n = 12,259). Mean age was 71 ± 11 years (range, 18 to 98 years). 93% had native AV disease, 48% underwent concomitant coronary artery bypass grafting, and 26% had additional valve surgery. There were 81,706 patient-years of systematic follow-up data available for analysis. Demographics, intraoperative variables, and 27,386 echocardiographic records were used to identify risks for explant for SVD and assess longitudinal changes in transprosthesis gradients using time-varying covariable analyses. Results Three hundred fifty-four explants were performed, with 41% related to endocarditis and 44% to SVD. Actuarial estimates of explant for SVD at 10 and 20 years were 1.9% and 15% overall, respectively, and in patients younger than 60 years, 5.6% and 46%, respectively. Younger age (p < 0.0001), lipid-lowering drugs (p = 0.002), prosthesis–patient mismatch (p = 0.001), and higher postoperative peak and mean AV gradients were associated with explant for SVD (p < 0.0001). The effect of gradient on SVD was greatest in patients younger than 60 years. Conclusions Durability of the Carpentier-Edwards PERIMOUNT aortic valve is excellent even in younger patients. Explant for SVD is related to gradient at implantation, especially in younger patients. Strategies to reduce early postoperative AV gradients, such as root enlargement or more efficient prostheses, should be considered. PMID:25662439

Durable usage of patient-reported outcome measures in clinical practice to monitor health-related quality of life in head and neck cancer patients.

PubMed

Duman-Lubberding, S; van Uden-Kraan, C F; Jansen, F; Witte, B I; Eerenstein, S E J; van Weert, S; de Bree, R; Leemans, C R; Verdonck-de Leeuw, I M

2017-12-01

To investigate the long-term follow-up (5 years) of implementing patient-reported outcome measures (PROMs) in clinical practice to monitor health-related quality of life (HRQOL) in head and neck cancer (HNC) patients. A mixed method design was used. The usage rate of OncoQuest (a touch screen computer system to monitor HRQOL) and the subsequent nurse consultation was calculated among HNC patients who visited the outpatient clinic for regular follow-up, as well as differences between ever users and never users (sociodemographic and clinical characteristics). The content of the nurse consultation was investigated. Reasons for not using (barriers) or using (facilitators) OncoQuest and the nurse consultation were explored from the perspective of HNC patients, and of head and neck surgeons. Usage rate of OncoQuest was 67% and of the nurse consultation 79%. Usage of OncoQuest was significantly related to tumor subsite and tumor stage. Topics most frequently (>40%) discussed during the nurse consultation were global quality of life (97%), head and neck cancer related symptoms (82%), other physical symptoms such as pain (61%), and psychological problems such as anxiety (44%). Several barriers and facilitators to implement PROMs in clinical practice were reported by both patients and head and neck surgeons. Usage of PROMs in clinical practice and a nurse consultation is durable, even 5 years after the introduction. This study contributes to better insight into long-term follow-up of implementation, thereby guiding future research and projects that aim to implement PROMs in clinical practice to monitor HRQOL among (head and neck) cancer patients.

Overall Survival and Long-Term Safety of Nivolumab (Anti-Programmed Death 1 Antibody, BMS-936558, ONO-4538) in Patients With Previously Treated Advanced Non-Small-Cell Lung Cancer.

PubMed

Gettinger, Scott N; Horn, Leora; Gandhi, Leena; Spigel, David R; Antonia, Scott J; Rizvi, Naiyer A; Powderly, John D; Heist, Rebecca S; Carvajal, Richard D; Jackman, David M; Sequist, Lecia V; Smith, David C; Leming, Philip; Carbone, David P; Pinder-Schenck, Mary C; Topalian, Suzanne L; Hodi, F Stephen; Sosman, Jeffrey A; Sznol, Mario; McDermott, David F; Pardoll, Drew M; Sankar, Vindira; Ahlers, Christoph M; Salvati, Mark; Wigginton, Jon M; Hellmann, Matthew D; Kollia, Georgia D; Gupta, Ashok K; Brahmer, Julie R

2015-06-20

Programmed death 1 is an immune checkpoint that suppresses antitumor immunity. Nivolumab, a fully human immunoglobulin G4 programmed death 1 immune checkpoint inhibitor antibody, was active and generally well tolerated in patients with advanced solid tumors treated in a phase I trial with expansion cohorts. We report overall survival (OS), response durability, and long-term safety in patients with non-small-cell lung cancer (NSCLC) receiving nivolumab in this trial. Patients (N = 129) with heavily pretreated advanced NSCLC received nivolumab 1, 3, or 10 mg/kg intravenously once every 2 weeks in 8-week cycles for up to 96 weeks. Tumor burden was assessed by RECIST (version 1.0) after each cycle. Median OS across doses was 9.9 months; 1-, 2-, and 3-year OS rates were 42%, 24%, and 18%, respectively, across doses and 56%, 42%, and 27%, respectively, at the 3-mg/kg dose (n = 37) chosen for further clinical development. Among 22 patients (17%) with objective responses, estimated median response duration was 17.0 months. An additional six patients (5%) had unconventional immune-pattern responses. Response rates were similar in squamous and nonsquamous NSCLC. Eighteen responding patients discontinued nivolumab for reasons other than progressive disease; nine (50%) of those had responses lasting > 9 months after their last dose. Grade 3 to 4 treatment-related adverse events occurred in 14% of patients. Three treatment-related deaths (2% of patients) occurred, each associated with pneumonitis. Nivolumab monotherapy produced durable responses and encouraging survival rates in patients with heavily pretreated NSCLC. Randomized clinical trials with nivolumab in advanced NSCLC are ongoing. © 2015 by American Society of Clinical Oncology.

Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

PubMed

Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

2010-01-01

This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

High-power and short-duration ablation for pulmonary vein isolation: Safety, efficacy, and long-term durability.

PubMed

Barkagan, Michael; Contreras-Valdes, Fernando M; Leshem, Eran; Buxton, Alfred E; Nakagawa, Hiroshi; Anter, Elad

2018-05-30

PV reconnection is often the result of catheter instability and tissue edema. High-power short-duration (HP-SD) ablation strategies have been shown to improve atrial linear continuity in acute pre-clinical models. This study compares the safety, efficacy and long-term durability of HP-SD ablation with conventional ablation. In 6 swine, 2 ablation lines were performed anterior and posterior to the crista terminalis, in the smooth and trabeculated right atrium, respectively; and the right superior PV was isolated. In 3 swine, ablation was performed using conventional parameters (THERMOCOOL-SMARTTOUCH ® SF; 30W/30 sec) and in 3 other swine using HP-SD parameters (QDOT-MICRO™, 90W/4 sec). After 30 days, linear integrity was examined by voltage mapping and pacing, and the heart and surrounding tissues were examined by histopathology. Acute line integrity was achieved with both ablation strategies; however, HP-SD ablation required 80% less RF time compared with conventional ablation (P≤0.01 for all lines). Chronic line integrity was higher with HP-SD ablation: all 3 posterior lines were continuous and transmural compared to only 1 line created by conventional ablation. In the trabeculated tissue, HP-SD ablation lesions were wider and of similar depth with 1 of 3 lines being continuous compared to 0 of 3 using conventional ablation. Chronic PVI without stenosis was evident in both groups. There were no steam-pops. Pleural markings were present in both strategies, but parenchymal lung injury was only evident with conventional ablation. HP-SD ablation strategy results in improved linear continuity, shorter ablation time, and a safety profile comparable to conventional ablation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Long-term survival, valve durability, and reoperation for 4 aortic root procedures combined with ascending aorta replacement.

PubMed

Svensson, Lars G; Pillai, Saila T; Rajeswaran, Jeevanantham; Desai, Milind Y; Griffin, Brian; Grimm, Richard; Hammer, Donald F; Thamilarasan, Maran; Roselli, Eric E; Pettersson, Gösta B; Gillinov, A Marc; Navia, Jose L; Smedira, Nicholas G; Sabik, Joseph F; Lytle, Bruce W; Blackstone, Eugene H

2016-03-01

To evaluate long-term results of aortic root procedures combined with ascending aorta replacement for aneurysms, using 4 surgical strategies. From January 1995 to January 2011, 957 patients underwent 1 of 4 aortic root procedures: valve preservation (remodeling or modified reimplantation, n = 261); composite biologic graft (n = 297); composite mechanical graft (n = 156); or allograft root (n = 243). Seven deaths occurred (0.73%), none after valve-preserving procedures, and 13 strokes (1.4%). Composite grafts exhibited higher gradients than allografts or valve preservation, but the latter 2 exhibited more aortic regurgitation (2.7% biologic and 0% mechanical composite grafts vs 24% valve-preserving and 19% allografts at 10 years). Within 2 to 5 years, valve preservation exhibited the least left ventricular hypertrophy, allograft replacement the greatest; however, valve preservation had the highest early risk of reoperation, allograft replacement the lowest. Patients receiving allografts had the highest risk of late reoperation (P < .05), and those receiving composite mechanical grafts and valve preservation had the lowest. Composite bioprosthesis patients had the highest risk of late death (57% at 15 years vs 14%-26% for the remaining procedures, P < .0001), because they were substantially older and had more comorbidities (P < .0001). These 4 aortic root procedures, combined with ascending aorta replacement, provide excellent survival and good durability. Valve-preserving and allograft procedures have the lowest gradients and best ventricular remodeling, but they have more late regurgitation, and likely, less risk of valve-related complications, such as bleeding, hemorrhage, and endocarditis. Despite the early risk of reoperation, we recommend valve-preserving procedures for young patients when possible. Composite bioprostheses are preferable for the elderly. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Per-oral Endoscopic Myotomy (POEM) After the Learning Curve: Durable Long-term Results With a Low Complication Rate.

PubMed

Hungness, Eric S; Sternbach, Joel M; Teitelbaum, Ezra N; Kahrilas, Peter J; Pandolfino, John E; Soper, Nathaniel J

2016-09-01

We aimed to report long-term outcomes for patients undergoing per-oral endoscopic myotomy (POEM) after our initial 15-case learning curve. POEM has become an established, natural-orifice surgical approach for treating esophageal motility disorders. To date, published outcomes and comparative-effectiveness studies have included patients from the early POEM experience. Consecutive patients undergoing POEM after our initial 15 cases, with a minimum of 1-year postoperative follow-up, were included. Treatment success was defined as an Eckardt score ≤3 without reintervention. Gastroesophageal reflux was defined by abnormal pH-testing or reflux esophagitis >Los Angeles grade A. Between January 2012 and March 2015, 115 patients underwent POEM at a single, high-volume center. Operative time was 101 ± 29 minutes, with 95% (109/115) of patients discharged on postoperative day 1. Clavien-Dindo grade III complications occurred in 2.7%, one of which required diagnostic laparoscopy to rule out Veress needle injury to the gall bladder. The rate of grade I complications was 15.2%. At an average of 2.4 years post-POEM (range 12-52 months), the overall success rate was 92%. Objective evidence of reflux was present in 40% for all patients and 33% for patients with a body mass index <35 kg/m and no hiatal hernia. POEM performed by experienced surgeons provided durable symptomatic relief in 94% of patients with nonspastic achalasia and 90% of patients with type 3 achalasia/spastic esophageal motility disorders, with a low rate of complications. The rate of gastroesophageal reflux was comparable with prior studies of both POEM and laparoscopic Heller myotomy.

Three-dimensional printed upper-limb prostheses lack randomised controlled trials: A systematic review

PubMed Central

Diment, Laura E; Thompson, Mark S; Bergmann, Jeroen HM

2017-01-01

Background: Three-dimensional printing provides an exciting opportunity to customise upper-limb prostheses. Objective: This review summarises the research that assesses the efficacy and effectiveness of three-dimensional printed upper-limb prostheses. Study design: Systematic review. Methods: PubMed, Web of Science and OVID were systematically searched for studies that reported human trials of three-dimensional printed upper-limb prostheses. The studies matching the language, peer-review and relevance criteria were ranked by level of evidence and critically appraised using the Downs and Black Quality Index. Results: After removing duplicates, 321 records were identified. Eight papers met the inclusion criteria. No studies used controls; five were case studies and three were small case-series studies. All studies showed promising results, but none demonstrated external validity, avoidance of bias or statistically significant improvements over conventional prostheses. The studies demonstrated proof-of-concept rather than assessing efficacy, and the devices were designed to prioritise reduction of manufacturing costs, not customisability for comfort and function. Conclusion: The potential of three-dimensional printing for individual customisation has yet to be fully realised, and the efficacy and effectiveness to be rigorously assessed. Until randomised controlled trials with follow-up are performed, the comfort, functionality, durability and long-term effects on quality of life remain unknown. Clinical relevance Initial studies suggest that three-dimensional printing shows promise for customising low-cost upper-limb prosthetics. However, the efficacy and effectiveness of these devices have yet to be rigorously assessed. Until randomised controlled trials with follow-up are performed, the comfort, functionality, durability and long-term effects on patient quality of life remain unknown. PMID:28649911

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neuhauser, K.

Through discussion of five case studies (test homes), this project evaluates strategies to elevate the performance of existing homes to a level commensurate with best-in-class implementation of high-performance new construction homes. The test homes featured in this research activity participated in Deep Energy Retrofit (DER) Pilot Program sponsored by the electric and gas utility National Grid in Massachusetts and Rhode Island. Building enclosure retrofit strategies are evaluated for impact on durability and indoor air quality in addition to energy performance. Evaluation of strategies is structured around the critical control functions of water, airflow, vapor flow, and thermal control. The aimmore » of the research project is to develop guidance that could serve as a foundation for wider adoption of high performance, 'deep' retrofit work. The project will identify risk factors endemic to advanced retrofit in the context of the general building type, configuration and vintage encountered in the National Grid DER Pilot. Results for the test homes are based on observation and performance testing of recently completed projects. Additional observation would be needed to fully gauge long-term energy performance, durability, and occupant comfort.« less

Isolated Pt Atoms Stabilized by Amorphous Tungstenic Acid for Metal-Support Synergistic Oxygen Activation.

PubMed

Zhang, Qian; Qin, Xixi; Duanmu, Fanpeng; Ji, Huiming; Shen, Zhurui; Han, Xiaopeng; Hu, Wenbin

2018-06-05

Oxygen activation plays a crucial role in many important chemical reactions such as organics oxidation and oxygen reduction. For developing highly active materials for oxygen activation, herein, we report an atomically dispersed Pt on WO3 nanoplates stabilized by in-situ formed amorphous H2WO4 out-layer and the mechanism for activating molecular oxygen. Experimental and theoretical studies demonstrate that the isolated Pt atoms coordinated with oxygen atoms from [WO6] and water of H2WO4, consequently leading to optimized surface electronic configuration and strong metal support interaction (SMSI). In exemplified reactions of butanone oxidation sensing and oxygen reduction, the atomic Pt/WO3 hybrid exhibits superior activity than those of Pt nanoclusters/WO3 and bare WO3 as well as enhanced long-term durability. This work will provide insight on the origin of activity and stability for atomically dispersed materials, thus promoting the development of highly efficient and durable single atom-based catalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Debonding damage analysis in composite-masonry strengthening systems with polymer- and mortar-based matrix by means of the acoustic emission technique

NASA Astrophysics Data System (ADS)

Verstrynge, E.; Wevers, M.; Ghiassi, B.; Lourenço, P. B.

2016-01-01

Different types of strengthening systems, based on fiber reinforced materials, are under investigation for external strengthening of historic masonry structures. A full characterization of the bond behavior and of the short- and long-term failure mechanisms is crucial to ensure effective design, compatibility with the historic substrate and durability of the strengthening solution. Therein, non-destructive techniques are essential for bond characterization, durability assessment and on-site condition monitoring. In this paper, the acoustic emission (AE) technique is evaluated for debonding characterization and localization on fiber reinforced polymer (FRP) and steel reinforced grout-strengthened clay bricks. Both types of strengthening systems are subjected to accelerated ageing tests under thermal cycles and to single-lap shear bond tests. During the reported experimental campaign, AE data from the accelerated ageing tests demonstrated the thermal incompatibility between brick and epoxy-bonded FRP composites, and debonding damage was successfully detected, characterized and located. In addition, a qualitative comparison is made with digital image correlation and infrared thermography, in view of efficient on-site debonding detection.

Fe3C nanoparticle decorated Fe/N doped graphene for efficient oxygen reduction reaction electrocatalysis

NASA Astrophysics Data System (ADS)

Niu, Yanli; Huang, Xiaoqin; Hu, Weihua

2016-11-01

Oxygen reduction reaction (ORR) electrocatalysts with high activity, low cost and good durability are crucial to promote the large-scale practical application of fuel cells. Particularly, iron carbide (Fe3C) supported on nitrogen-doped carbon has recently demonstrated compelling promise for ORR electrocatalysis. In this paper, we report the facile synthesis of mesoporous Fe/N-doped graphene with encapsulated Fe3C nanoparticles (Fe3C@Fe/N-graphene) and its superior ORR catalytic activity. This hybrid material was synthesized by the spontaneous oxidative polymerization of dopamine on graphene oxide (GO) sheets in the presence of iron ion, followed by thermal annealing in Argon (Ar) atmosphere. As-prepared material shows high ORR catalytic activity with overwhelming four-electron reduction pathway, long-term durability and high methanol tolerance in alkaline media. This work reports a facile method to synthesize promising ORR electrocatalysis with multiple components and hierarchical architecture, and may offer valuable insight into the underlying mechanism of Fe3C-boosted ORR activity of Fe/N doped carbon.

Thermomechanical analysis and durability of commercial micro-porous polymer Li-ion battery separators

NASA Astrophysics Data System (ADS)

Love, Corey T.

2011-03-01

Static and dynamic thermomechanical analysis was performed with a dynamic mechanical analyzer (DMA) to identify thermal and mechanical transitions for commercially available polymer separators under mechanical loading. Clear transitions in deformation mode were observed at elevated temperatures. These transitions identified the onset of separator "shutdown" which occurred at temperatures below the polymer melting point. Mechanical loading direction was critical to the overall integrity of the separator. Anisotropic separators (Celgard 2320, 2400 and 2500) were mechanically limited when pulled in tensile in the transverse direction. The anisotropy of these separators is a result of the dry technique used to manufacture the micro-porous membranes. Separators prepared using the wet technique (Entek Gold LP) behaved more uniformly, or biaxially, where all mechanical properties were nearly identical within the separator plane. The information provided by the DMA can also be useful for predicting the long-term durability of polymer separators in lithium-ion batteries exposed to electrolyte (solvent and salt), thermal fluctuations and electrochemical cycling. Small losses in mechanical integrity were observed for separators exposed to the various immersion environments over the 4-week immersion time.

Antagonist effects of calcium on borosilicate glass alteration

NASA Astrophysics Data System (ADS)

Mercado-Depierre, S.; Angeli, F.; Frizon, F.; Gin, S.

2013-10-01

Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon-calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass-cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C-S-H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon-calcium interactions on glass durability and open the way for a better understanding of glass-cement mixing in civil engineering applications as well as in nuclear waste storage.

A phase 2 study of ofatumumab (Arzerra®) in combination with a pan-AKT inhibitor (afuresertib) in previously treated patients with chronic lymphocytic leukemia (CLL).

PubMed

Chen, Christine I; Paul, Harminder; Le, Lisa W; Wei, Ellen N; Snitzler, Susi; Wang, Trina; Levina, Olga; Kakar, Sumeet; Lau, Anthea; Queau, Michelle; Johnston, James B; Smith, Deborah A; Trudel, Suzanne

2018-06-19

AKT plays a centralized role in tumor proliferation and survival and is aberrantly activated in chronic lymphocytic leukemia (CLL). In this phase 2 trial, 30 relapsed/refractory CLL patients were treated with combination afuresertib, a novel oral AKT inhibitor, and ofatumumab for 6 months, followed by afuresertib maintenance for 12 months. We aimed to achieve deeper and more durable responses, without requiring long-term continuous treatment. Treatment was generally well tolerated but respiratory infections were common, with 18% severe requiring hospitalization. Hematologic toxicities were manageable (grade 3-4 neutropenia 39%). At a median follow-up of 13.4 months, overall responses were 50% (complete responses 3.6%). Median progression-free survival was 8.5 months and overall survival 34.8 months. Combination therapy with ofatumumab and afuresertib is active and well tolerated, but does not appear to lead to durable responses and may not provide additional benefit over single-agent ofatumumab in relapsed/refractory CLL. Novel agent combinations are currently undergoing intense investigation.

Efficiency and durability of a self-cleaning coating on concrete and stones under both natural and artificial ageing trials

NASA Astrophysics Data System (ADS)

Carmona-Quiroga, P. M.; Martínez-Ramírez, S.; Viles, H. A.

2018-03-01

This study aimed to test the performance under long-term working conditions of a commercial self-cleaning coating, a water-based TiO2 sol, on three building materials important in recent and older European heritage; Portland limestone, Woodkirk sandstone and concrete. First, the compatibility of the coating (effect on petrophysical properties) with the substrates was demonstrated by examining aesthetic properties and water vapour permeability of the building materials and secondly, the self-cleaning ability of the TiO2 nanoparticles in degrading artificial stain (rhodamine B) under UV light was evaluated. Finally, the durability (lasting performance) of photocatalytic activity was assessed during one year of outdoor exposure trial and 2000 h of accelerated ageing in a chamber with UV radiation and condensation cycles. Results showed that photocatalytic activity was unaltered on concrete, whereas on sandstone, particularly after artificial ageing, it was reduced due to the removal of nanoparticles from the surface. On limestone, a decrease of TiO2 content was observed but photodegradation efficiency (ability to perform as self-cleaner) seemed not to be affected.

Smooth, All-Solid, Low-Hysteresis, Omniphobic Surfaces with Enhanced Mechanical Durability.

PubMed

Boban, Mathew; Golovin, Kevin; Tobelmann, Brian; Gupte, Omkar; Mabry, Joseph M; Tuteja, Anish

2018-04-11

The utility of omniphobic surfaces stems from their ability to repel a multitude of liquids, possessing a broad range of surface tensions and polarities, by causing them to bead up and either roll or slide off. These surfaces may be self-cleaning, corrosion-resistant, heat-transfer enhancing, stain-resistant or resistant to mineral- or biofouling. The majority of reported omniphobic surfaces use texture, lubricants, and/or grafted monolayers to engender these repellent properties. Unfortunately, these approaches often produce surfaces with deficiencies in long-term stability, durability, scalability, or applicability to a wide range of substrates. To overcome these limitations, we have fabricated an all-solid, substrate-independent, smooth, omniphobic coating composed of a fluorinated polyurethane and fluorodecyl polyhedral oligomeric silsesquioxane. Liquids of varying surface tension, including water, hexadecane, ethanol, and silicone oil, exhibit low-contact-angle hysteresis (<15°) on these surfaces, allowing liquid droplets to slide off, leaving no residue. Moreover, we demonstrate that these robust surfaces retained their repellent properties more effectively than textured or lubricated omniphobic surfaces after being subjected to mechanical abrasion.

Testing the impact and durability of a group malleability intervention in the context of the Israeli-Palestinian conflict.

PubMed

Goldenberg, Amit; Cohen-Chen, Smadar; Goyer, J Parker; Dweck, Carol S; Gross, James J; Halperin, Eran

2018-01-23

Fostering perceptions of group malleability (teaching people that groups are capable of change and improvement) has been shown to lead to short-term improvements in intergroup attitudes and willingness to make concessions in intractable conflicts. The present study, a field intervention involving 508 Israelis from three locations in Israel, replicated and substantially extended those findings by testing the durability of a group malleability intervention during a 6-month period of frequent violence. Three different 5-hour-long interventions were administered as leadership workshops. The group malleability intervention was compared with a neutral coping intervention and, importantly, with a state-of-the-art perspective-taking intervention. The group malleability intervention proved superior to the coping intervention in improving attitudes, hope, and willingness to make concessions, and maintained this advantage during a 6-month period of intense intergroup conflict. Moreover, it was as good as, and in some respects superior to, the perspective-taking intervention. These findings provide a naturalistic examination of the potential of group malleability interventions to increase openness to conflict resolution.

Polylactic Acid-Based Polymer Blends for Durable Applications

NASA Astrophysics Data System (ADS)

Finniss, Adam

There has been considerable scientific interest in both research and commercial communities as of late in the area of biologically based or sourced plastics. As the consumption of petroleum rises and concerns about climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use PLA more widely, especially in durable applications. Unfortunately, PLA has several drawbacks that hinder more widespread usage of the material as a durable item: it has low ductility and impact strength in bulk applications, along with poor stability in the face of heat, humidity or liquid media. To combat these deficiencies, a number of techniques were investigated. Samples were annealed to create crystalline domains that would improve mechanical properties and reduce diffusion, blended with graphene to create barriers to diffusion throughout the material, or compounded with a polycarbonate (PC) polymer phase to protect the PLA phase and to enhance the mechanical properties of the blend. If a material containing biologically sourced components with good mechanical properties can be created, it would be desirable for durable uses such as electronics components or as an automotive grade resin. Crystallization experiments were carried out in a differential scanning calorimeter to determine the effects of heat treatment and additives on the rather slow crystallization kinetics of PLA polymer. It was determined that the blending in of the PC phase did not significantly alter the kinetics or mechanism of crystal growth. The addition of graphene to any PC/PLA formulation served as a nucleating agent which speeded up the crystallization kinetics markedly, in some cases by several orders of magnitude. Results obtained from these experiments were internally consistent, 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 was fully protected by the more stable phase. Lastly, molded parts of differing thicknesses were hydrolytically degraded to examine the effects of diffusion resistance on the mechanical properties of untreated PC/PLA blends. It was determined that, similar to the droplet morphology study, the effect of PC content was the most dominating factor in the durability of the formulations. In fact, if molded parts reach a critical thickness, a transition from ductile to brittle failure modes can be observed. The rate of diffusion through the materials was also determined to be much faster than the rate of PLA hydrolysis. It is concluded that the most effective way to create a durable material containing a significant bio-based content is to completely encapsulate PLA polymer with the more stable polycarbonate phase. Materials containing up to about 30% PLA at maximum were shown to be sufficiently durable so that they may be employed in similar automotive and electrical applications as for pure polycarbonate. (Abstract shortened by UMI.)

Long-Term Outcomes of Cognitive-Behavioral Therapy for Adolescent Body Dysmorphic Disorder.

PubMed

Krebs, Georgina; de la Cruz, Lorena Fernández; Monzani, Benedetta; Bowyer, Laura; Anson, Martin; Cadman, Jacinda; Heyman, Isobel; Turner, Cynthia; Veale, David; Mataix-Cols, David

2017-07-01

Emerging evidence suggests that cognitive-behavioral therapy (CBT) is an efficacious treatment for adolescent body dysmorphic disorder (BDD) in the short term, but longer-term outcomes remain unknown. The current study aimed to follow up a group of adolescents who had originally participated in a randomized controlled trial of CBT for BDD to determine whether treatment gains were maintained. Twenty-six adolescents (mean age = 16.2, SD = 1.6) with a primary diagnosis of BDD received a course of developmentally tailored CBT and were followed up over 12 months. Participants were assessed at baseline, midtreatment, posttreatment, 2-, 6-, and 12-month follow-up. The primary outcome measure was the clinician-rated Yale-Brown Obsessive-Compulsive Scale Modified for BDD. Secondary outcomes included measures of insight, depression, quality of life, and global functioning. BDD symptoms decreased significantly from pre- to posttreatment and remained stable over the 12-month follow-up. At this time point, 50% of participants were classified as responders and 23% as remitters. Participants remained significantly improved on all secondary outcomes at 12-month follow-up. Neither baseline insight nor baseline depression predicted long-term outcomes. The positive effects of CBT appear to be durable up to 12-month follow-up. However, the majority of patients remained symptomatic and vulnerable to a range of risks at 12-month follow-up, indicating that longer-term monitoring is advisable in this population. Future research should focus on enhancing the efficacy of CBT in order to improve long-term outcomes. Copyright © 2017. Published by Elsevier Ltd.

Durability of small-for-size living donor allografts.

PubMed

Au, Kin Pan; Chan, See Ching; Chok, Kenneth Siu Ho; Chan, Albert Chi Yan; Wong, Tiffany Cho Lam; Sharr, William Wei; Lo, Chung Mau

2015-11-01

Our aim was to study the long-term outcomes of living donor liver transplantation using small-for-size (SFS) grafts. From July 2002 to July 2009, 233 patients received a right liver graft with a middle hepatic vein from a living donor in our center. Recipients were stratified according to the graft weight to recipient standard liver volume (GW/SLV) ratio into 4 groups: >50% (n = 89), >40% to 50% (n = 85), >35% to 40% (n = 38), and ≤ 35% (n = 21). They were compared in terms of graft survivals, biliary stricture rates, renal function in terms of estimated glomerular filtration rate (eGFR), platelet counts, and graft function in terms of serum bilirubin and international normalized ratio (INR). The 5-year graft survivals for patients with GW/SLV of >50%, >40% to 50%, >35% to 40% and ≤ 35% were 88.8%, 88.2%, 81.5%, and 81.0%, respectively. Transplantation for hepatocellular carcinoma affected graft survivals (P = 0.02), but graft size did not (P = 0.66). There were no differences in frequency of biliary stricture (21.3% versus 17.1% versus 21.1% versus 28.6%; P = 0.75). At each year after transplant, their platelet counts (P = 0.12-0.65), eGFR (P = 0.49-0.91), bilirubin (P = 0.14-0.51), and INR (P = 0.20-0.98) remained comparable. SFS grafts with GW/SLV ≤ 35% and >35% to 40% had comparable long-term outcomes with larger liver grafts. Graft size did not affect long-term graft survivals. © 2015 American Association for the Study of Liver Diseases.

Durable Flap-Valve Mitigation of Duodenogastric Reflux,  Remnant Gastritis and Dumping Syndrome Following Billroth I Reconstruction.

PubMed

Hoya, Yoshiyuki; Taki, Tetsuya; Watanabe, Atsushi; Nakayoshi, Tomoko; Okamoto, Tomoyoshi; Mitsumori, Norio; Yanaga, Katsuhiko

2016-04-01

We have reported the short-term results of pylorus reconstruction gastrectomy (PRG) that prevents duodenogastric reflux (DGR) and remnant gastritis after distal gastrectomy. We herein report the long-term results of the PRG. PRG was performed in 37 patients (age 31 to 86 [mean 67.8 ± 12.3] years, male:female = 22:15) with gastric cancer from June 2006 through December 2013. We examined the long-term outcome in 28 patients (age 41 to 86 [mean 67.0 ± 10.7] years, male:female = 18:10) that passed over 3 years after surgery (LTR 44.1 ± 11.7 months), and compared with their short-term result after the operation (STR 13.1 ± 6.9 months). The adverse events of gastric surgery evaluated in this study consisted of the degree of remnant gastritis, the presence of dumping syndrome, and degree of weight loss (%). There was no difference in the degree of DGR and remnant gastritis by gastroscopic finding between LTR and STR after PRG (P = 0.21). Statistically, there was no difference in the bile acid concentration of remnant gastric juice between LTR and STR (108.4 ± 254.1 vs. 94.0 ± 208.6 μmol/L, P = 0.33), and weight loss of LTR was the same as that of STR (5.67 ± 7.08 vs. 4.59 ± 5.63%, P = 0.34). There were few morphological changes in the reconstructed pylorus by the long-term course, but 2 patients showed mild atrophy. The form of reconstructed pylorus and the effect that reduces side effects of Billroth I seem to last for a long time.

Three-year follow-up of treatment-naïve and previously treated patients with CLL and SLL receiving single-agent ibrutinib

PubMed Central

Furman, Richard R.; Coutre, Steven E.; Burger, Jan A.; Blum, Kristie A.; Coleman, Morton; Wierda, William G.; Jones, Jeffrey A.; Zhao, Weiqiang; Heerema, Nyla A.; Johnson, Amy J.; Shaw, Yun; Bilotti, Elizabeth; Zhou, Cathy; James, Danelle F.; O'Brien, Susan

2015-01-01

Ibrutinib is an orally administered inhibitor of Bruton tyrosine kinase that antagonizes B-cell receptor, chemokine, and integrin-mediated signaling. In early-phase studies, ibrutinib demonstrated high response rates and prolonged progression-free survival (PFS) in chronic lymphocytic leukemia (CLL). The durable responses observed with ibrutinib relate in part to a modest toxicity profile that allows the majority of patients to receive continuous therapy for an extended period. We report on median 3-year follow-up of 132 patients with symptomatic treatment-naïve and relapsed/refractory CLL or small lymphocytic lymphoma. Longer treatment with ibrutinib was associated with improvement in response quality over time and durable remissions. Toxicity with longer follow-up diminished with respect to occurrence of grade 3 or greater cytopenias, fatigue, and infections. Progression remains uncommon, occurring primarily in some patients with relapsed del(17)(p13.1) and/or del(11)(q22.3) disease. Treatment-related lymphocytosis remains largely asymptomatic even when persisting >1 year and does not appear to alter longer-term PFS and overall survival compared with patients with partial response or better. Collectively, these data provide evidence that ibrutinib controls CLL disease manifestations and is well tolerated for an extended period; this information can help direct potential treatment options for different subgroups to diminish the long-term risk of relapse. PMID:25700432

Adhesive Bonding of Titanium to Carbon-Carbon Composites for Heat Rejection Systems

NASA Technical Reports Server (NTRS)

Cerny, Jennifer; Morscher, Gregory

2006-01-01

High temperature adhesives with good thermal conductivity, mechanical performance, and long term durability are crucial for the assembly of heat rejection system components for space exploration missions. In the present study, commercially available adhesives were used to bond high conductivity carbon-carbon composites to titanium sheets. Bonded pieces were also exposed to high (530 to 600 Kelvin for 24 hours) and low (liquid nitrogen 77K for 15 minutes) temperatures to evaluate the integrity of the bonds. Results of the microstructural characterization and tensile shear strengths of bonded specimens will be reported. The effect of titanium surface roughness on the interface microstructure will also be discussed.

Optimal use of atherectomy in critical limb ischemia.

PubMed

Rundback, John H; Herman, Kevin Chaim

2014-09-01

Critical limb ischemia (CLI) is the most severe and debilitating form of peripheral arterial disease and is associated with high rates of limb loss and cardiovascular mortality. The unique physical environment of tibial occlusive disease underlying most CLI cases limits treatment options and long-term durability, with resulting frequent rates of persistent obstruction, restenosis, and reintervention. Atherectomy represents a potential strategy to improve acute and late results when treating patients with CLI. Available atherectomy devices each have specific performance characteristics, evidentiary rationale, and limitations that mandate a clear understanding of the optimal albeit evolving use of this category of interventional tools. Copyright © 2014 Elsevier Inc. All rights reserved.

Advanced composite vertical fin for L-1011 aircraft

NASA Technical Reports Server (NTRS)

Jackson, A. C.

1984-01-01

The structural box of the L-1011 vertical fin was redesigned using advanced composite materials. The box was fabricated and ground tested to verify the structural integrity. This report summarizes the complete program starting with the design and analysis and proceeds through the process development ancillary test program production readiness verification testing, fabrication of the full-scale fin boxes and the full-scale ground testing. The program showed that advanced composites can economically and effectively be used in the design and fabrication of medium primary structures for commercial aircraft. Static-strength variability was demonstrated to be comparable to metal structures and the long term durability of advanced composite components was demonstrated.

Endovascular Repair of Abdominal Aortic Aneurysms

PubMed Central

Sternbergh, W. Charles; Yoselevitz, Moises; Money, Samuel R.

1999-01-01

Endovascular treatment of abdominal aortic aneurysms (AAAs) is an exciting new minimally invasive treatment option for patients with this disease. Ochsner Clinic has been the only institution in the Gulf South participating in FDA clinical trials of these investigational devices. Early results with endovascular AAA repair demonstrate a trend towards lower mortality and morbidity when compared with traditional open surgery. Length of stay has been reduced by two-thirds with a marked reduction in postoperative pain and at-home convalescence. If the long-term data on efficacy and durability of these devices are good, most AAAs in the future will be treated with this minimally invasive technique. PMID:21845135

A program for advancing the technology of space concentrators

NASA Technical Reports Server (NTRS)

Naujokas, Gerald J.; Savino, Joseph M.

1989-01-01

In 1985, the NASA Lewis Research Center formed a project, the Advanced Solar Dynamics Power Systems Project, for the purpose of advancing the technology of Solar Dynamic Power Systems for space applications beyond 2000. Since then, technology development activities have been initiated for the major components and subsystems such as the concentrator, heat receiver and engine, and radiator. Described here is a program for developing long lived (10 years or more), lighter weight, and more reflective space solar concentrators than is presently possible. The program is progressing along two parallel paths: one is concentrator concept development and the other is the resolution of those critical technology issues that will lead to durable, highly specular, and lightweight reflector elements. Outlined are the specific objectives, long-term goals, approach, planned accomplishments for the future, and the present status of the various program elements.

A program for advancing the technology of space concentrators

NASA Technical Reports Server (NTRS)

Naujokas, Gerald J.; Savino, Joseph M.

1989-01-01

In 1985, the NASA Lewis Research Center formed a project, the Advanced Solar Dynamics Power Systems Project, for the purpose of advancing the technology of Solar Dynamic Power Systems for space applications beyond 2000. Since then, technology development activities have been initiated for the major components and subsystems such as the concentrator, heat receiver and engine, and radiator. Described here is a program for developing long lived (10 years or more), lighter weight, and more reflective space solar concentrators than is presently possible. The program is progressing along two parallel paths: one is concentrator concept development and the other is the resolution of those critical technology issues that will lead to durable, highly specular, and lightweight reflector elements. Outlined are the specific objectives, long term goals, approach, planned accomplishments for the future, and the present status of the various program elements.

Long-term monitoring FBG-based cable load sensor

NASA Astrophysics Data System (ADS)

Zhang, Zhichun; Zhou, Zhi; Wang, Chuan; Ou, Jinping

2006-03-01

Stay cables are the main load-bearing components of stayed-cable bridges. The cables stress status is an important factor to the stayed-cable bridge structure safety evaluation. So it's very important not only to the bridge construction, but also to the long-term safety evaluation for the bridge structure in-service. The accurate measurement for cable load depends on an effective sensor, especially to meet the long time durability and measurement demand. FBG, for its great advantage of corrosion resistance, absolute measurement, high accuracy, electro-magnetic resistance, quasi-distribution sensing, absolute measurement and so on, is the most promising sensor, which can cater for the cable force monitoring. In this paper, a load sensor has been developed, which is made up of a bushing elastic supporting body, 4 FBGs uniformly-spaced attached outside of the bushing supporting body, and a temperature compensation FBG for other four FBGs, moreover a cover for protection of FBGs. Firstly, the sensor measuring principle is analyzed, and relationship equation of FBG wavelength shifts and extrinsic load has also been gotten. And then the sensor calibration experiments of a steel cable stretching test with the FBG load sensor and a reference electric pressure sensor is finished, and the results shows excellent linearity of extrinsic load and FBG wavelength shifts, and good repeatability, which indicates that such kind of FBG-based load sensor is suitable for load measurement, especially for long-term, real time monitoring of stay-cables.

Measuring impact: a cross-sectional multi-stage cluster survey to assess the attainment of durable solutions in post-tsunami Aceh, Indonesia.

PubMed

Lee, Christopher; Doocy, Shannon; Deli, Anwar; Kirsch, Thomas; Weiss, William; Robinson, Courtland

2014-11-17

There exists little agreement on the choice of indicators to be used to assess the impact of humanitarian assistance. The 2004 Indian Ocean tsunami led to significant mortality and displacement in Aceh Province, Indonesia, as well as a nearly unprecedented humanitarian response. Six years after the disaster we conducted an impact assessment of humanitarian services rendered in Aceh using a comprehensive set of rights-based indicators and sought to determine modifiable predictors of improved outcomes in disaster-affected households. A sample of 597 returned and non-returned households in Banda Aceh and Meulaboh was selected using a multistage stratified cluster survey design. We employed principle components analysis and the Framework on Durable Solutions for Internally Displaced Persons to develop a comprehensive and rights-based approach to humanitarian impact measurement using multivariate regression models. The attainment of durable solutions was equivalent in both returned households 100.1 [CI] 97.63-102.5) and households that integrated elsewhere (99.37 [CI] 95.43-103.3, P = 0.781). Standard of living as well as education and health facility satisfaction increased significantly whereas monthly income decreased after the tsunami, from 2585241 IDR ([CI] 2357202-2813279 IDR) to 2038963 ([CI] 1786627-2291298 IDR, P < 0.001). Shelter (P = 0.007) and legal assistance (P < 0.001) were both significantly associated with positive durable solutions outcomes, whereas prolonged displacement duration was significantly associated with poorer outcomes (P < 0.001). Livelihood assistance received after one year was associated with higher odds of increasing or maintaining pre-tsunami income levels (OR = 3.02, P = 0.008), whereas livelihood assistance received within one year was associated with lower odds of attaining pre-tsunami income (OR = 0.52, P = 0.010). We find that after adjusting for pre-tsunami conditions and tsunami-related damages, the impact of sectoral responses can be assessed. The duration of displacement was the strongest negative predictive factor for the attainment of durable solutions, suggesting that measures to reduce displacement time may be effective in mitigating the long-term effects of disaster on households. The durable solutions framework is a novel and effective impact measurement tool and can be used to identify factors amenable to intervention and inform future disaster recovery efforts.

Atomic oxygen durability evaluation of the flexible batten for the photovoltaic array mast on Space Station

NASA Technical Reports Server (NTRS)

Stidham, Curtis R.; Rutledge, Sharon K.; Sechkar, Edward A.; Flaherty, David S.; Roig, David M.; Edwards, Jonathan L.

1994-01-01

A test program was conducted at the National Aeronautics and Space Administration's Lewis Research Center (LeRC) to evaluate the long term low Earth orbital (LEO) atomic oxygen (AO) durability of a flexible (fiberglass-epoxy composite) batten. The flexible batten is a component used to provide structural rigidity in the photovoltaic array mast on Space Station. The mast is used to support and articulate the photovoltaic array, therefore, the flexible batten must be preloaded for the 15 year lifetime of an array blanket. Development hardware and composite materials were evaluated in ground testing facilities for AO durability and dynamic retraction-deployment cyclic loading representative of expected full life in-space application. The CV1144 silicone (AO protective) coating was determined to provide adequate protection against AO degradation of the composite material and provided fiber containment, thus the structural integrity of the flexible batten was maintained. Both silicone coated and uncoated flexible battens maintained load carrying capabilities. Results of the testing did indicate that the CV1144 silicone protective coating was oxidized by AO reactions to form a brittle glassy (SiO2) skin that formed cracking patterns on all sides of the coated samples. The cracking was observed in samples that were mechanically stressed as well as samples in non-stressed conditions. The oxidized silicon was observed to randomly spall in small localized areas, on the flexible battens that underwent retraction-deployment cycling. Some darkening of the silicon, attributed to vacuum ultraviolet (VUV) radiation, was observed.

Improving the durability of the optical fiber sensor based on strain transfer analysis

NASA Astrophysics Data System (ADS)

Wang, Huaping; Jiang, Lizhong; Xiang, Ping

2018-05-01

To realize the reliable and long-term strain detection, the durability of optical fiber sensors has attracted more and more attention. The packaging technique has been considered as an effective method, which can enhance the survival ratios of optical fiber sensors to resist the harsh construction and service environment in civil engineering. To monitor the internal strain of structures, the embedded installation is adopted. Due to the different material properties between host material and the protective layer, the monitored structure embedded with sensors can be regarded as a typical model containing inclusions. Interfacial characteristic between the sensor and host material exists obviously, and the contacted interface is prone to debonding failure induced by the large interfacial shear stress. To recognize the local interfacial debonding damage and extend the effective life cycle of the embedded sensor, strain transfer analysis of a general three-layered sensing model is conducted to investigate the failure mechanism. The perturbation of the embedded sensor on the local strain field of host material is discussed. Based on the theoretical analysis, the distribution of the interfacial shear stress along the sensing length is characterized and adopted for the diagnosis of local interfacial debonding, and the sensitive parameters influencing the interfacial shear stress are also investigated. The research in this paper explores the interfacial debonding failure mechanism of embedded sensors based on the strain transfer analysis and provides theoretical basis for enhancing the interfacial bonding properties and improving the durability of embedded optical fiber sensors.

Crystallization in high-level waste glass: A review of glass theory and noteworthy literature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christian, J. H.

2015-08-18

There is a fundamental need to continue research aimed at understanding nepheline and spinel crystal formation in high-level waste (HLW) glass. Specifically, the formation of nepheline solids (K/NaAlSiO 4) during slow cooling of HLW glass can reduce the chemical durability of the glass, which can cause a decrease in the overall durability of the glass waste form. The accumulation of spinel solids ((Fe, Ni, Mn, Zn)(Fe, Cr) 2O 4), while not detrimental to glass durability, can cause an array of processing problems inside HLW glass melters. In this review, the fundamental differences between glass and solid-crystals are explained using kinetic,more » thermodynamic, and viscosity arguments, and several highlights of glass-crystallization research, as it pertains to high-level waste vitrification, are described. In terms of mitigating spinel in the melter and both spinel and nepheline formation in the canister, the complexity of HLW glass and the intricate interplay between thermal, chemical, and kinetic factors further complicates this understanding. However, new experiments seeking to elucidate the contributing factors of crystal nucleation and growth in waste glass, and the compilation of data from older experiments, may go a long way towards helping to achieve higher waste loadings while developing more efficient processing strategies. Higher waste loadings and more efficient processing strategies will reduce the overall HLW Hanford Tank Waste Treatment and Immobilization Plant (WTP) vitrification facilities mission life.« less

Will permanent LVADs be better than heart transplantation?

PubMed

Massad, M G; McCarthy, P M

1997-04-01

Current interest in permanent mechanical support systems has been renewed as a result of the present shortage of human heart donors, and in view of the satisfactory results obtained with their use as a bridge-to-transplant. As the number of donors is unlikely to increase dramatically in the near future, there is an urgent need to develop mechanical alternatives to transplantation. Preliminary data on the use of the implantable electric LVAD as a bridge-to-transplant indicate that the adverse clinical and mechanical events in outpatients are few and do not preclude use of the device on a permanent basis. Except for infections, transplant issues relating to need for endomyocardial biopsies, rejection, malignancies, and graft arteriosclerosis do not apply to LVAD recipients who face important issues relating to device durability, cost, and potential need for concomitant right heart support. This lack of data on long-term durability contrasts with a yearly mortality rate of about 5% after the first year of transplant. With the initiation of clinical trials on the permanent use of the electric LVAD, several design modifications and upgrading of the currently available devices are expected. Completely sealed systems with steadily improving durability will hopefully appear. Inductive coupling techniques under investigation and development appear to be able to transmit energy without damage across the skin. It is anticipated that with more reliable electronic microprocessors, the future generation of implantable LVADs will be smaller, more reliable and longer lasting.

Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation

DOE PAGES

White, Claire E.; Olds, Daniel P.; Hartl, Monika; ...

2017-02-01

The long-term durability of cement-based materials is influenced by the pore structure and associated permeability at the sub-micrometre length scale. With the emergence of new types of sustainable cements in recent decades, there is a pressing need to be able to predict the durability of these new materials, and therefore nondestructive experimental techniques capable of characterizing the evolution of the pore structure are increasingly crucial for investigating cement durability. Here, small-angle neutron scattering is used to analyze the evolution of the pore structure in alkali-activated materials over the initial 24 h of reaction in order to assess the characteristic poremore » sizes that emerge during these short time scales. By using a unified fitting approach for data modeling, information on the pore size and surface roughness is obtained for a variety of precursor chemistries and morphologies (metakaolin- and slag-based pastes). Furthermore, the impact of activator chemistry is elucidatedviathe analysis of pastes synthesized using hydroxide- and silicate-based activators. It is found that the main aspect influencing the size of pores that are accessible using small-angle neutron scattering analysis (approximately 10–500 Å in diameter) is the availability of free silica in the activating solution, which leads to a more refined pore structure with smaller average pore size. Furthermore, as the reaction progresses the gel pores visible using this scattering technique are seen to increase in size.« less

Serious delinquent behavior as part of a significantly handicapping condition: cures and supportive environments.

PubMed Central

Wolf, M M; Braukmann, C J; Ramp, K A

1987-01-01

The past 20 years have been productive ones for the field of applied behavior analysis. A brief review of our own efforts during this period reveals that we have accomplished several but not all of our goals for the Teaching-Family approach. In this context, we note that the setting of realistic and appropriate goals is important for the field and for society. Moreover, we suggest that the realistic goal for some persons with serious delinquent behavior may be extended supportive and socializing treatment rather than permanent cure from conventional short-term treatment programs. We base this suggestion on the accumulating evidence that serious delinquent behavior may often be part of a significantly disabling and durable condition that consists of multiple antisocial and dysfunctional behaviors, often runs in families, and robustly eludes effective short-term treatment. Like other significant disabilities such as retardation, autism, and blindness, the effects of this condition may be a function of an interaction of environmental and constitutional variables. We argue that our field has the wherewithal to construct effective and humane long-term supportive environments for seriously delinquent youths. In this regard, we explore the dimensions, rationales, logistics, and beginnings of a new treatment direction that involves long-term supportive family treatment. We contend that such supportive families may be able to provide long, perhaps even lifetime, socializing influences through models, values, and contingencies that seem essential for developing and maintaining prosocial behavior in these high-risk youths. PMID:3323156

Operational durability of a giant ER valve for Braille display

NASA Astrophysics Data System (ADS)

Luning, Xu; Han, Li; Yufei, Li; Shen, Rong; Kunquan, Lu

2017-05-01

The compact configuration of giant ER (electrorheological) valves provides the possibility of realizing a full-page Braille display. The operational durability of ER valves is a key issue in fulfilling a Braille display. A giant ER valve was used to investigate the variations in pressure drops and critical pressure drops of the valves over a long period under some typical operational parameters. The results indicate that neither the pressure drops nor critical pressure drops of giant ER valves show apparent deterioration over a long period. Without ER fluid exchange, a blockage appears in the channel of the valve because the ER structures induced by an external electric field cannot be broken by the Brownian motion of hydraulic oil molecules when the external electric field is removed. Forcing ER fluid flow is an effective and necessary method to keep the channel of the valve unblocked. Thus the operational durability of the valve using giant ER fluids is able to meet the demands of Braille display.

Stent-assisted coiling of intracranial aneurysms using LEO stents: long-term follow-up in 153 patients.

PubMed

Sedat, Jacques; Chau, Yves; Gaudart, Jean; Sachet, Marina; Beuil, Stephanie; Lonjon, Michel

2018-02-01

Coiling associated with placement of a self-expandable intracranial stent has improved the treatment of intracranial wide-necked aneurysms. Little is known, however, about the durability of this treatment. The purpose of this report is to present our experience with the LEO stent and to evaluate the complications, effectiveness, and long-term results of this technique. We analyzed the records of 155 intracranial unruptured aneurysms that were treated by stent-assisted coiling with a LEO stent between 2008 and 2012. Procedural, early post-procedural, and delayed complications were recorded. Clinical and angiographic follow-up of patients was conducted over a period of at least 36 months. No procedural mortality was observed. One-month morbidity was observed in 14 out of 153 patients (9,15%). One hundred thirty-eight patients (with 140 aneurysms) had clinical and angiographic follow-up for more than 36 months. No aneurysm rupture was observed during follow-up. Four patients presented an intra-stent stenosis at 8 months, and 6 patients who had an early recurrence were retreated. Final results showed 85% complete occlusion, 13% neck remnants, and 2% stable incomplete occlusion. Stent-assisted coiling with the LEO stent is a safe and effective treatment for unruptured intracranial aneurysms. The long-term clinical outcomes with the LEO stent are excellent with a high rate of complete occlusion that is stable over time.

Long-term care survey reveals challenges. Facilities grapple with five broad issues, including changes in leadership and AIDS.

PubMed

Westhoff, L J; Schaefer, J C

1993-05-01

The Catholic Health Association's 1992 survey of Catholic long-term care (LTC) facilities identified five broad issues LTC facilities face in the 1990s: leadership, system affiliation, community programs, resident issues, and care of persons with AIDS. The transition to lay leadership presents new challenges to the relationship between LTC facilities and their sponsors. Despite the dominance of religious sponsors, an increasing number of laypersons are serving as healthcare administrators both in long-term and acute care. Thirty percent of respondents reported being affiliated with a multi-institutional system. This percentage has changed little in the past few years, although the number of facilities that are system members continues to increase at the fastest rate of any type of LTC facility. Only 27 percent of survey respondents said they provide educational or informational programs for persons in their communities. Thirty-nine percent of system-affiliated LTC facilities reported offering such programs. One encouraging finding shows that 80 percent of facilities have written policies for living wills, 64 percent for designated proxy, and 86 percent for durable power of attorney for healthcare. LTC providers are struggling to determine their role in caring for persons with HIV and AIDS. Only 3.6 percent of respondents care for residents with AIDS. A major problem LTC administrators face is a fear of potential infection of staff or residents.

Left heart bypass support with the Rotaflow Centrifugal Pump® as a bridge to decision and recovery in an adult.

PubMed

Kashiwa, Koichi; Nishimura, Takashi; Saito, Aya; Kubo, Hitoshi; Fukaya, Aoi; Tamai, Hisayoshi; Yambe, Tomoyuki; Kyo, Shunei; Ono, Minoru

2012-06-01

Since left heart bypass or biventricular circulatory assist with an extracorporeal centrifugal pump as a bridge to decision or recovery sometimes requires long-time support, the long-term durability of extracorporeal centrifugal pumps is crucial. The Rotaflow Centrifugal Pump(®) (MAQUET Cardiopulmonary AG, Hirrlingen, Germany) is one of the centrifugal pumps available for long-term use in Japan. However, there have been few reports of left heart bypass or biventricular circulatory support over the mid-term. This is a case report of left heart bypass support with the Rotaflow Centrifugal Pump(®) as a bridge to decision and recovery for an adult patient who could not be weaned from cardiopulmonary bypass and percutaneous cardiopulmonary support after cardiac surgery. We could confirm that the patient's consciousness level was normal; however, the patient could not be weaned from the left heart bypass support lasting 1 month. Therefore, the circulatory assist device was switched to the extracorporeal Nipro ventricular assist device (VAD). This time, left heart bypass support could be maintained for 30 days using a single Rotaflow Centrifugal Pump(®). There were no signs of hemolysis during left heart bypass support. The Rotaflow Centrifugal Pump(®) itself may be used as a device for a bridge to decision or recovery before using a VAD in cardiogenic shock patients.

Peritoneum: a noble membrane in long-term dialysis treatment.

PubMed

Barone, Roberto J; Campora, María I; Gimenez, Nélida S; Ramirez, Liliana; Santopietro, Mónica; Grbavac, Drago; Pattin, Mauricio; Panese, Sergio A

2009-01-01

The durability of the peritoneum as a dialysis membrane is as yet an unanswered question. Peritonitis episodes have an important effect in long-term treatment. To evaluate survival of the peritoneum for dialysis, we analyzed peritoneal failure related to technique dropout because of peritonitis, inadequate dialysis, and ultrafiltration disorders. We retrospectively analyzed data for 89 peritoneal dialysis patients who had been treated for at least 3 months [52 women, 37 men; mean age: 50.91 +/- 13.72 years (range: 22 - 81 years)] from August 4, 1993, to July 1, 2008. The Kaplan-Meier method was used to measure peritoneum survival, with only a definitive switch to hemodialysis or death from peritonitis, ultrafiltration failure, or inadequate dialysis as endpoints. Total treatment time was 5008 patient-months (mean: 55 +/- 44 patient-months), and the historical annual rate of peritonitis was 0.37 per year at risk (1 episode in 32.52 patient-months). Of the 89 patients, 19 dropped treatment because of peritonitis and 1 because of ultrafiltration failure. Peritoneum survival was 98.8%, 93.7%, 87.6%, 66.9%, 46.4%, and 33.8% at 1, 3, 5, 8, 10, and 14 years. In the 15 years of our program, peritoneum failure represented less than 1.5% of drop-out causes annually. The peritoneum is a reliable membrane to reach dialysis targets in long-term therapy.

Estimation of metallic structure durability for a known law of stress variation

NASA Astrophysics Data System (ADS)

Mironov, V. I.; Lukashuk, O. A.; Ogorelkov, D. A.

2017-12-01

Overload of machines working in transient operational modes leads to such stresses in their bearing metallic structures that considerably exceed the endurance limit. The estimation of fatigue damages based on linear summation offers a more accurate prediction in terms of machine durability. The paper presents an alternative approach to the estimation of the factors of the cyclic degradation of a material. Free damped vibrations of the bridge girder of an overhead crane, which follow a known logarithmical decrement, are studied. It is shown that taking into account cyclic degradation substantially decreases the durability estimated for a product.

Brief Report: Long-Term (96-Week) Efficacy and Safety After Switching From Tenofovir Disoproxil Fumarate to Tenofovir Alafenamide in HIV-Infected, Virologically Suppressed Adults

PubMed Central

Raffi, François; Orkin, Chloe; Clarke, Amanda; Slama, Laurence; Gallant, Joel; Daar, Eric; Henry, Keith; Santana-Bagur, Jorge; Stein, David K.; Bellos, Nicholaos; Scarsella, Anthony; Yan, Mingjin; Abram, Michael E.; Cheng, Andrew

2017-01-01

Abstract: In a double-blind, phase 3 trial, 663 HIV-infected, virologically suppressed adults were randomized to switch to tenofovir alafenamide (TAF; n = 333) vs. remain on tenofovir disoproxil fumarate (TDF; n = 330), each coformulated with emtricitabine (FTC), while continuing their third agent (boosted protease inhibitor or unboosted third agent). At week 96, 88.6% on FTC/TAF and 89.1% on FTC/TDF had HIV-1 RNA <50 copies per milliliter [adjusted difference −0.5% (95% confidence interval: −5.3 to 4.4%)]. Proteinuria, albuminuria, proximal renal tubular function, and bone mineral density improved after switching to TAF- from TDF-containing regimens. These longer-term data support FTC/TAF as a safe, well-tolerated, and durable nucleotide reverse transcriptase inhibitor backbone. PMID:28272164

The use of local natural stone in construction of St. Petersburg region and south-east Finland

NASA Astrophysics Data System (ADS)

Luodes, Hannu; Härmä, Paavo; Panova, Elena; Pirinen, Heikki; Selonen, Olavi

2013-04-01

A three-year project, started in 2012, "Efficient use of natural stone in the Leningrad region and South-East Finland", studies the use and durability of natural stone in the city environments in the Nordic climate and especially along the Eastern Baltic Sea coastline between Helsinki and St. Petersburg. The project is lead by the Geological Survey of Finland (GTK) and the partners in the project are Saimaa University of Applied Sciences from Finland and Federal State Unitary Enterprise "Petersburg Complex Geological Expedition" Russian together with Saint-Petersburg State University from the Russian Federation. As associates in this project are also natural stone companies from Finland, Ylämaa Group Oy and Palin Granit Oy. The project is co-funded by the European Union, the Russian Federation and the Republic of Finland through the European Neighbourhood and Partnership Instrument (ENPI). A great potential of natural stone that can be used in construction is located in the border zone between South-East Finland and the Leningrad region. Rapakivi granite from that area has been utilized for several important buildings worldwide since 18th century and the area holds still potential for future economic growth. The use of the stone particularly from this area is based on its visual expression and good properties with high durability and long life cycle that can be used as arguments in the future development. Strengthening of the knowledge of the material reserves in the area gives a long term basement for economic development. Special aim of the project is to promote the use of natural stone in the city construction, especially the use of left-over stone generated in the production. In the project the use of natural stone in larger cities from the 18th century until today including the towns St. Petersburg, Vyborg, Helsinki, Kuopio and Kotka will be reported. Also an analysis of the near future needs of natural stone (qualities and quantities) in reconstruction and construction in the southern Finland and St. Petersburg regions will be documented. That is to generate ideas for definition of new environmental building products using left-over natural stone from quarrying. The project will provide detailed data about long term durability of stone structures in the cities that are along the Baltic Sea shoreline (St. Petersburg, Helsinki) and subject to both mechanical and biological weathering. Mechanical weathering by several annual freeze-thaw cycles is especially typical in these coastal climate conditions. The data will be used in characterization of the durability and weathering mechanisms of different stone types and is used in preparation of guidelines of stone selection for construction and renovation. The data on natural stone resources in the project area will be evaluated and collected in a database. Also the best natural stone evaluation methods from Finland and Russia will be assessed to produce a guidance of best practices for prospecting and evaluation of natural stone occurrences. The project will also generate suggestions for making the natural stone trade between the EU and Russia easier.

Long-term follow-up of Dupuytren disease after injection of triamcinolone acetonide in Chinese patients in Taiwan.

PubMed

Yin, C-Y; Yu, H-H M; Wang, J-P; Huang, Y-C; Huang, T-F; Chang, M-C

2017-09-01

Injection of triamcinolone acetonide is a non-operative treatment for early-stage Dupuytren disease in Caucasians, but its effectiveness in non-Caucasians is unclear. We report averaged 5-year follow-up results of 37 patients (49 affected hands) with early-stage Dupuytren disease for patients in Taiwan (non-Caucasian) who received a single dose of 5 mg triamcinolone acetonide injection into nodules monthly for 3 months. Using ultrasound, we recorded no progression of sizes of the modules following injection after 6 months. After an average 5-year follow-up, two patients with three hands (6%) experienced reactivation of the treated nodules. None required surgical intervention. Ultrasound examination showed that sizes of the treated Dupuytren nodules decreased significantly by 40% 6 months after injection and 56% at the final follow-up. We conclude that in these Chinese patients in Taiwan with early Dupuytren nodules, triamcinolone acetonide injection was effective in reducing the size of the Dupuytren nodules and maintaining long-term durable control of the nodular growth. III.

Does long term exposure to radon gas influence the properties of polymeric waterproof materials?

NASA Astrophysics Data System (ADS)

Navratilova Rovenska, Katerina; Jiranek, Martin; Kokes, Pavel; Wasserbauer, Richard; Kacmarikova, Veronika

2014-01-01

The technical state of buildings and the quality of the indoor environment depend on the quality of the waterproofing course and on the properties of the insulating materials that are applied, in particular on their durability, long-term functional reliability and resistance to corrosive effects of the subsoil. Underground water chemistry and soil bacteria are well-known corrosive agents. Our investigations indicate that the ageing process of waterproof materials can be significantly accelerated by alpha particles emitted by radon and radon progenies which are present in soil gas. Materials commonly available on the building market, e.g. LDPE and HDPE of various densities, PVC, TPO (thermoplastic polyolefin), PP (polypropylene) and EPDM were selected for our experimental study. The preliminary results for 3-year exposure to radon gas show a decrease in tensile strength to 60%, elongation to 80% and hardness to 95% for samples based on PE. The diffusion coefficient of radon for samples based on PVC decreased to 20% of the initial value after 1-year exposure to radon and soil bacteria.

The economics of new age arthroplasty: can we afford it?

PubMed

Sculco, Thomas P

2010-09-07

New technology in joint replacement design and materials adds cost that must be documented by improved outcomes. This is not always the case as the recent metal/metal data has shown. The current economics of arthroplasty have put increasing financial pressure on hospitals and will progress under new health care legislation. New technology must be cost-effective and this will be increasingly difficult in an era of outstanding long-term results with current designs. Cost may necessitate less expensive alternatives, eg, generic implants, in arthroplasty patients. Joint replacement surgery has evolved over the past 4 decades into a highly successful surgical procedure. Earlier designs and materials that demonstrated inferior functional and long-term results have disappeared in a Darwinian fashion. Through this evolutionary process many of the current designs have proven efficacy and durability. Current outcome data indicates that hip and knee designs demonstrate 90% to 95% success rates at 15-year follow-up. Technologic advances are necessary to improve implant design and materials, however, only in an environment of reduced reimbursement to hospitals can the increase cost be justified. Copyright 2010, SLACK Incorporated.

Roux-en-Y Gastric Bypass and Vertical Banded Gastroplasty Induce Long-Term Changes on the Human Gut Microbiome Contributing to Fat Mass Regulation.

PubMed

Tremaroli, Valentina; Karlsson, Fredrik; Werling, Malin; Ståhlman, Marcus; Kovatcheva-Datchary, Petia; Olbers, Torsten; Fändriks, Lars; le Roux, Carel W; Nielsen, Jens; Bäckhed, Fredrik

2015-08-04

Bariatric surgery is currently the most effective procedure for the treatment of obesity. Given the role of the gut microbiota in regulating host metabolism and adiposity, we investigated the long-term effects of bariatric surgery on the microbiome of patients randomized to Roux-en-Y gastric bypass or vertical banded gastroplasty and matched for weight and fat mass loss. The two surgical procedures induced similar and durable changes on the gut microbiome that were not dependent on body mass index and resulted in altered levels of fecal and circulating metabolites compared with obese controls. By colonizing germ-free mice with stools from the patients, we demonstrated that the surgically altered microbiota promoted reduced fat deposition in recipient mice. These mice also had a lower respiratory quotient, indicating decreased utilization of carbohydrates as fuel. Our results suggest that the gut microbiota may play a direct role in the reduction of adiposity observed after bariatric surgery. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Facing the rain after the phase out: Performance evaluation of alternative fluorinated and non-fluorinated durable water repellents for outdoor fabrics.

PubMed

Schellenberger, S; Gillgard, P; Stare, A; Hanning, A; Levenstam, O; Roos, S; Cousins, I T

2018-02-01

Fluorinated durable water repellent (DWR) agents are used to obtain water and stain repellent textiles. Due to the on-going phase-out of DWRs based on side-chain fluorinated polymers (SFP) with "long" perfluoroalkyl chains, the textile industry lacks suitable alternatives with comparable material characteristics. The constant development and optimization of SFPs for textile applications initiated more than half a century ago has resulted in a robust and very efficient DWR-technology and textiles with exceptional hydro- and oleo-phobic properties. The industry is now in the predicament that the long-chain SFPs with the best technical performance have undesirable toxicological and environmental behaviour. This study provides a comprehensive overview of the technical performance of presently available fluorinated and non-fluorinated DWRs as part of a chemical alternatives assessment (CAA). The results are based on a study with synthetic outdoor fabrics treated with alternative DWRs and tested for repellency using industrial standard and complementary methods. Using this approach, the complex structure-property relationships of DWR-polymers could be explained on a molecular level. Both short-chain SFPs and non-fluorinated DWRs showed excellent water repellency and durability in some cases while short-chain SFPs were the more robust of the alternatives to long-chain SFPs. A strong decline in oil repellency and durability with perfluoroalkyl chain length was shown for SFP DWRs. Non-fluorinated alternatives were unable to repel oil, which might limit their potential for substitution in textile application that require repellency towards non-polar liquids. Copyright © 2017. Published by Elsevier Ltd.

Durable antibody responses following one dose of the bivalent human papillomavirus L1 virus-like particle vaccine in the Costa Rica Vaccine Trial.

PubMed

Safaeian, Mahboobeh; Porras, Carolina; Pan, Yuanji; Kreimer, Aimee; Schiller, John T; Gonzalez, Paula; Lowy, Douglas R; Wacholder, Sholom; Schiffman, Mark; Rodriguez, Ana C; Herrero, Rolando; Kemp, Troy; Shelton, Gloriana; Quint, Wim; van Doorn, Leen-Jan; Hildesheim, Allan; Pinto, Ligia A

2013-11-01

The Costa Rica HPV16/18 Vaccine Trial (CVT) showed that four-year vaccine efficacy against 12-month HPV16/18 persistent infection was similarly high among women who received one, two, or the recommended three doses of the bivalent HPV16/18 L1 virus-like particle (VLP) vaccine. Live-attenuated viral vaccines, but not simple-subunit vaccines, usually induce durable lifelong antibody responses after a single dose. It is unclear whether noninfectious VLP vaccines behave more like live-virus or simple-subunit vaccines in this regard. To explore the likelihood that efficacy will persist longer term, we investigated the magnitude and durability of antibodies to this vaccine by measuring HPV16- and HPV18-specific antibodies by VLP-ELISA using serum from enrollment, vaccination, and annual visits through four years in four vaccinated groups; one-dose (n = 78), two-doses separated by one month (n = 140), two doses separated by six months (n = 52), and three scheduled doses (n = 120, randomly selected). We also tested enrollment sera from n = 113 HPV16- or HPV18 L1-seropositive women prevaccination, presumably from natural infection. At four years, 100% of women in all groups remained HPV16/18 seropositive; both HPV16/18 geometric mean titers (GMT) among the extended two-dose group were non-inferior to the three-dose group, and ELISA titers were highly correlated with neutralization titers in all groups. Compared with the natural infection group, HPV16/18 GMTs were, respectively, at least 24 and 14 times higher among the two-dose and 9 and 5 times higher among one-dose vaccinees. Antibody levels following one-dose remained stable from month 6 through month 48. Results raise the possibility that even a single dose of HPV VLPs will induce long-term protection. ©2013 AACR.

Endovascular stent-graft repair of failed endovascular abdominal aortic aneurysm repair.

PubMed

Baril, Donald T; Silverberg, Daniel; Ellozy, Sharif H; Carroccio, Alfio; Jacobs, Tikva S; Sachdev, Ulka; Teodorescu, Victoria J; Lookstein, Robert A; Marin, Michael L

2008-01-01

Despite high initial technical success, the long-term durability of endovascular abdominal aortic aneurysm repair (EVAR) continues to be a concern. Following EVAR, patients can experience endoleaks, device migration, device fractures, or aneurysm growth that may require intervention. The purpose of this study was to review all patients treated with secondary endovascular devices at our institution for failed EVAR procedures. Over an 8-year period, 988 patients underwent EVAR, of whom 42 (4.3%) required secondary interventions involving placement of additional endovascular devices. Data regarding patient characteristics, aneurysm size, initial device type, time until failure, failure etiology, secondary interventions, and outcomes were reviewed. The mean time from initial operation until second operation was 34.1 months. Failures included type I endoleaks in 38 patients (90.5%), type III endoleaks in two patients (4.8%), and enlarging aneurysms without definite endoleaks in two patients (4.8%). The overall technical success rate for secondary repair was 92.9% (39/42). Perioperative complications occurred in nine patients (21.4%), including wound complications (n = 6), cerebrovascular accident (CVA) (n = 1), foot drop (n = 1), and death (n = 1). Mean follow-up following secondary repair was 16.4 months (range 1-50). Eighty-six percent of patients treated with aortouni-iliac devices had successful repairs compared to 45% of patients treated with proximal cuffs. Ten patients (23.8%) had persistent or recurrent type I or type III endoleaks following revision. Of these, four had tertiary interventions, including two patients who had additional devices placed. Failures following EVAR occur in a small but significant number of patients. When anatomically possible, endovascular revision offers a safe means of treating these failures. Aortouni-iliac devices appear to offer a more durable repair than the proximal cuff for treatment of proximal type I endoleaks. Midterm results indicate that these patients may require additional procedures but have a low rate of aneurysm-related mortality. Longer-term follow-up is necessary to determine the durability of these endovascular revisions.

Minimally invasive or conventional edge-to-edge repair for severe mitral regurgitation due to bileaflet prolapse in Barlow's disease: does the surgical approach have an impact on the long-term results?

PubMed

De Bonis, Michele; Lapenna, Elisabetta; Del Forno, Benedetto; Di Sanzo, Stefania; Giacomini, Andrea; Schiavi, Davide; Vicentini, Luca; Latib, Azeem; Pozzoli, Alberto; Pappalardo, Federico; La Canna, Giovanni; Alfieri, Ottavio

2017-07-01

To evaluate whether the adoption of a right minithoracotomy operative approach had an impact on the long-term results of edge-to-edge (EE) repair compared to conventional sternotomy in patients with Barlow's disease and bileaflet prolapse. We assessed the long-term results of 104 patients with Barlow's disease treated with a minimally invasive EE technique. An equal number of patients had a conventional median sternotomy EE repair for the same disease and were used as a control group. The inverse probability of treatment weighting was used to create comparable distributions of the covariates that were significantly different at baseline in the two groups. We performed a comparative analysis of the groups. No hospital deaths were observed. Follow-up was 99.5% complete (median 11.3 years). The cumulative incidence function (CIF) of cardiac death at 12 years, with noncardiac death as a competing risk, showed no difference between the two groups ( P  = 0.87). At 12 years, the CIF of recurrent MR ≥ 3+, with death as the competing risk, was 7% in the sternotomy group and 5% in the minimally invasive group ( P  = 0.30), and the CIF of recurrence of MR ≥ 2+ was 15 and 14%, respectively ( P  = 0.63). The type of surgical approach was not a predictor of cardiac death, reoperation, recurrent MR ≥ 3+ or recurrent MR ≥ 2+. A minimally invasive approach does not have a negative impact on the effectiveness and long-term durability of the EE repair for bileaflet prolapse in Barlow's disease. Long-term outcomes are excellent, and valvular performance remains stable over time with no evidence of mitral stenosis. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Transparent gel composite films with multiple functionalities: Long-lasting anti-fogging, underwater superoleophobicity and anti-bacterial activity.

PubMed

England, Matt W; Sato, Tomoya; Urata, Chihiro; Wang, Liming; Hozumi, Atsushi

2017-11-01

Transparent gel-based composite films with multiple functionalities, showing long-lasting anti-fogging properties, underwater superoleophobicity, and anti-bacterial activity were successfully prepared from polyvinylpyrrolidone (PVP) and aminopropyl-functionalized clay (AMP-clay). Due to the addition of glutaraldehyde (GA, cross-linker) into the PVP matrices, and AMP-functionalities to the substrate surfaces, both the adhesion properties in water and durability of the anti-fogging properties were significantly improved. In addition, this durability was also found to be markedly improved by increasing the film thickness via deposition of several PVP/AMP/GA layers, while still retaining excellent transparency. Copyright © 2017 Elsevier Inc. All rights reserved.

The Long-term Durability of Intra-operatively Placed Palmaz Stents for the Treatment of Type Ia Endoleaks After EVAR of Abdominal Aortic Aneurysm.

PubMed

Abdulrasak, M; Resch, T; Sonesson, B; Holst, J; Kristmundsson, T; Dias, N V

2017-01-01

The objective was to analyze the long-term durability of intra-operatively placed Palmaz stents for type Ia endoleaks, and the evolution of aneurysm neck morphology. This was a retrospective cohort study conducted at a tertiary referral centre. Patients treated between 1998 and 2012 were reviewed with regard to pre-, intra-, and post-operative data. Crude and relative survival estimates were calculated, with the latter referring only to patients with ≥ 3 months' follow-up. In total, 125 patients were included (83 elective, 22 ruptures, 20 symptomatic). Nine patients died perioperatively (two elective, seven acute). Median follow-up was 43 months (range 15-72). Seven patients had late abdominal aortic aneurysm related deaths. There were 51 re-interventions (seven type Ia endoleak related). Five year crude primary, primary assisted, and secondary success rates were 55 ± 5%, 66 ± 5%, and 70 ± 5%, respectively. These crude rates were superior for elective patients (p = .008, p = .031, and p = .037, respectively), but the relative rates were not (p = .187, p = .640, p = .558, respectively). Primary and assisted freedom from type Ia endoleak 5 years post-operatively were 84 ± 4% and 89 ± 3%, respectively. These rates were superior in elective patients (p = .066 and p = .145, respectively), especially when relative rates were analysed (p = .025 and p = .063, respectively). The visceral aortic diameter increased significantly between the first and the last post-operative imaging in 15/91 (16%), 12/91 (13%), 34/91 (37%), and 30/91 (33%) patients at the levels of coeliac trunk, superior mesenteric artery, lowest renal artery, and 9 mm distal to lowest renal artery, respectively. Intra-operatively placed Palmaz stents confer high long-term freedom from type Ia endoleak. Palmaz stents are an acceptable intra-operative bailout tool in the acute setting, but should not be used to extend elective infrarenal endovascular aneurysm repair to more demanding anatomies. Copyright © 2016 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Transport properties of damaged materials. Cementitious barriers partnership

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langton, C.

2014-11-01

The objective of the Cementitious Barriers Partnership (CBP) project is to develop tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in low-level waste storage applications. One key concern for the long-term durability of concrete is the degradation of the cementitious matrix, which occurs as a result of aggressive chemical species entering the material or leaching out in the environment, depending on the exposure conditions. The objective of the experimental study described in this report is to provide experimental data relating damage in cementitious materials to changes in transport properties, whichmore » can eventually be used to support predictive model development. In order to get results within a reasonable timeframe and to induce as much as possible uniform damage level in materials, concrete samples were exposed to freezing and thawing (F/T) cycles. The methodology consisted in exposing samples to F/T cycles and monitoring damage level with ultrasonic pulse velocity measurements. Upon reaching pre-selected damage levels, samples were tested to evaluate changes in transport properties. Material selection for the study was motivated by the need to get results rapidly, in order to assess the relevance of the methodology. Consequently, samples already available at SIMCO from past studies were used. They consisted in three different concrete mixtures cured for five years in wet conditions. The mixtures had water-to-cement ratios of 0.5, 0.65 and 0.75 and were prepared with ASTM Type I cement only. The results showed that porosity is not a good indicator for damage caused by the formation of microcracks. Some materials exhibited little variations in porosity even for high damage levels. On the other hand, significant variations in tortuosity were measured in all materials. This implies that damage caused by internal pressure does not necessarily create additional pore space in the microstructure, but likely creates new thin pathways between existing pore space for species to travel. These results have a significant impact on modeling efforts. Models relating porosity to tortuosity and permeability are unlikely to provide the correct basis for predicting long-term durability of concrete sustaining internal pressures and microcrack formation. Other avenues like the modeling of internal crystallization pressure need to be explored.« less

Laparoscopic sleeve gastrectomy in Asia: Long term outcome and revisional surgery.

PubMed

Pok, Eng-Hong; Lee, Wei-Jei; Ser, Kong-Han; Chen, Jung-Chien; Chen, Shu-Chun; Tsou, Ju-Juin; Chin, Kin-Fah

2016-01-01

Laparoscopic sleeve gastrectomy (LSG) is a popular stand-alone bariatric surgery, despite a paucity of long-term data. Hence, this study is to report the long-term outcome of LSG as primary bariatric procedure and the result of revisional surgery. With retrospective analysis of a prospective bariatric database, participants who defaulted clinic follow-up were interviewed by telephone. A total of 667 LSG was performed as primary bariatric procedure (2006-2012) with mean age of 34.5 ± 9.7 years old, female 74.7%, mean body mass index (BMI) 37.3 ± 8.1 kg/m(2). A 36-F bougie was used for all cases. There were 61 patients available with long-term data. The weight loss outcome at 1 year, 2 years, 3 years, 4 years, and 5 years showed a mean BMI 26.3, 25.2, 25.3, 27.1, and 26.2 with mean excess weight loss (EWL) 76.0%, 79.6%, 77.3%, 73.4%, and 72.6% respectively. However, 17% patients developed de novo gastro-esophageal reflux disease (GERD). Eighteen patients (2.2%) needed surgical revisions due to weight regain (n = 6), persistent type 2 diabetes mellitus (T2DM; n = 2), stricture (n = 2), and GERD (n = 8). The revision resulted in an additional mean excess weight loss of 23.8% with mean BMI 24.9 kg/m(2) at 6 months postoperatively. There was a 23.7% mean reduction of HbA1c with one patient who was in complete diabetic remission at 1 year. Our results showed LSG is a durable bariatric procedure with > 70% EWL at 5 years despite a high incidence of GERD. The need for revision of LSG is low and mainly for GERD. Copyright © 2015. Published by Elsevier Taiwan.

Long-term management of type 2 diabetes with glucagon-like peptide-1 receptor agonists.

PubMed

Courtney, Hamish; Nayar, Rahul; Rajeswaran, Chinnadorai; Jandhyala, Ravi

2017-01-01

Continuously reducing excess blood glucose is a primary goal for the management of type 2 diabetes (T2D). Most patients with T2D require glucose-lowering medications to achieve and maintain adequate glycemic control; however, treatment failure may occur, limiting treatment options. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are an emerging therapeutic class that can be prescribed for patients instead of basal insulin after the failure of oral therapies. Recent studies have focused on the durability and tolerability of long-term GLP-1RA therapy. This review summarizes the key efficacy and safety findings from prospective phase 3 clinical studies of at least 76 weeks' duration for the GLP-1RAs currently approved in the United States and the European Union (albiglutide, dulaglutide, exenatide twice daily [BID], exenatide once weekly [QW], liraglutide, and lixisenatide). Currently, most of the long-term data are from uncontrolled extension studies, and continuous patient benefit has been observed for up to 3 years with multiple GLP-1RAs. Four-year comparative data demonstrated a longer time to treatment failure for exenatide BID than for sulfonylurea, and 3-year comparative extension data demonstrated greater glycated hemoglobin (HbA1c) reductions and weight loss with exenatide QW than with insulin glargine. Currently, the longest extension study for a GLP-1RA is the DURATION-1 study of exenatide QW, with >7 years of clinical data available. Data from DURATION-1 demonstrated that continuous HbA1c reductions and weight loss were observed for the patients continuing on the treatment, with no unexpected adverse events. Taken together, these data support GLP-1RAs as a long-term noninsulin treatment option after the failure of oral therapies.

Vedolizumab Induces Long-term Mucosal Healing in Patients With Crohn's Disease and Ulcerative Colitis.

PubMed

Noman, Maja; Ferrante, Marc; Bisschops, Raf; De Hertogh, Gert; Van den Broeck, Karolien; Rans, Karen; Rutgeerts, Paul; Vermeire, Séverine; Van Assche, Gert

2017-09-01

Vedolizumab has proven efficacy in inflammatory bowel disease [IBD], but long-term mucosal healing in Crohn's disease [CD], as well as the incidence of colorectal neoplasia in IBD, among patients treated with vedolizumab have not been studied. We aimed to document mucosal healing and to explore the risk of colorectal neoplasia with vedolizumab maintenance therapy. Surveillance colonoscopy was prospectively scheduled for patients with longstanding ulcerative coltis [UC] or CD at a tertiary referral centre, in the open-label extension phase (vedolizumab 300 mg intravenously [IV] every 4 weeks) of the Gemini studies [GEMINI LTS, study number NCT00790933]. Mayo score ≤ 1 or ulcer disappearance [in CD] was defined as mucosal healing. Targeted biopsies were graded for inflammation and dysplasia. Of 68 patients [29 CD/39 UC] treated for ≥ 1 year [median 3.2 years, range 1.1-6.1], 58 [24 CD/34 UC] were endoscopically monitored. Durable endoscopic healing corrected by non-responder imputation was found in 7/24, 29% [CD] and 17/34, 50% [UC]. Combined histological and mucosal healing was observed in 5/24 [CD] and 11/34 [UC] of those with endoscopic healing. Low-grade dysplasia was detected in 10% of patients and high-grade dysplasia in the resection specimen of one patient with biopsy-proven low-grade dysplasia. Long-term endoscopic and histological healing was observed in a proportion of patients treated with vedolizumab long-term. The dysplasia risk with vedolizumab deserves further study. Copyright © 2017 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com

Liquid nitrogen spray cryotherapy in Barrett's esophagus with high-grade dysplasia: long-term results.

PubMed

Gosain, Sonia; Mercer, Kim; Twaddell, William S; Uradomo, Lance; Greenwald, Bruce D

2013-08-01

Liquid nitrogen endoscopic spray cryotherapy can safely and effectively eradicate high-grade dysplasia in Barrett's esophagus (BE-HGD). Long-term data on treatment success and safety are lacking. To assess the long-term safety and efficacy of spray cryotherapy in patients with BE-HGD. Single-center, retrospective study. Tertiary-care referral center. A total of 32 patients with BE-HGD of any length. Patients were treated with liquid nitrogen spray cryotherapy every 8 weeks until complete eradication of HGD (CE-HGD) and intestinal metaplasia (CE-IM) was found by endoscopic biopsy. Surveillance endoscopy with biopsies was performed for at least 2 years. CE-HGD, CE-IM, durability of response, disease progression, and adverse events. CE-HGD was 100% (32/32), and CE-IM was 84% (27/32) at 2-year follow-up. At last follow-up (range 24-57 months), CE-HGD was 31/32 (97%), and CE-IM was 26/32 (81%). Recurrent HGD was found in 6 (18%), with CE-HGD in 5 after repeat treatment. One patient progressed to adenocarcinoma, downgraded to HGD after repeat cryotherapy. BE segment length ≥3 cm was associated with a higher recurrence of IM (P = .004; odds ratio 22.6) but not HGD. No serious adverse events occurred. Stricture was seen in 3 patients (9%), all successfully dilated. Retrospective study design, small sample size. In patients with BE-HGD, liquid nitrogen spray cryotherapy has an acceptable safety profile and success rate for eliminating HGD and IM and is associated with a low rate of recurrence or progression to cancer with long-term follow-up. Copyright © 2013 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

[LONG TERM FOLLOW-UP OF TRANSCATHETER SELF EXPANDABLE AORTIC VALVE IMPLANTATION].

PubMed

Chen, Shmuel; Zenios, Vicky; Gilon, Dan; Planer, David; Beeri, Ronen; Lotan, Chaim; Danenberg, Haim D

2018-03-01

Aortic stenosis is the most common significant valvular disease in the western world. These patients are treated operatively unless they are at high operative risk or inoperable. During the last decade an alternative approach has evolved - transcatheter aortic valve implantation (TAVI). This method was shown to be at least as effective and safe as the operative one. However, very little data exists on long term follow-up (5 years and above), especially regarding valve durability and patient survival. To present a long term follow-up on patients who underwent transcutaneous self-expandable aortic valve implantation in our department between the years 2008-2011. In September 2008 the first CoreValve implantation was performed in Israel at Hadassah Medical Center. All records of patients who were transplanted between 9.2008 and 10.2011 were reviewed. The function of the valve early after the procedure was compared to its function at the end of the follow-up period. A total of 38 patients (out of 71) survived at least 54 months, of them, 19 have an echocardiography examination at the end of the follow-up period. In all patients the implanted valve was found to function well at the end of the follow-up period, without significant stenosis or paravalvular leak. In fact, in approximately half of these patients, the degree of paravalvular leak decreased during the follow-up period. On long term (5 years) follow-up of patients who were implanted with the self-expandable aortic valve (CoreValve), no deterioration of the valve was observed. In fact, in approximately half of the patients, a decrease in the severity of the paravalvular leak was demonstrated.

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.

A heterologous prime-boost Ebola virus vaccine regimen induces durable neutralizing antibody response and prevents Ebola virus-like particle entry in mice.

PubMed

Chen, Tan; Li, Dapeng; Song, Yufeng; Yang, Xi; Liu, Qingwei; Jin, Xia; Zhou, Dongming; Huang, Zhong

2017-09-01

Ebola virus (EBOV) is one of the most virulent pathogens known to humans. Neutralizing antibodies play a major role in the protection against EBOV infections. Thus, an EBOV vaccine capable of inducing a long-lasting neutralizing antibody response is highly desirable. We report here that a heterologous prime-boost vaccine regimen can elicit durable EBOV-neutralizing antibody response in mice. A chimpanzee serotype 7 adenovirus expressing EBOV GP (denoted AdC7-GP) was generated and used for priming. A truncated version of EBOV GP1 protein (denoted GP1t) was produced at high levels in Drosophila S2 cells and used for boosting. Mouse immunization studies showed that the AdC7-GP prime/GP1t boost vaccine regimen was more potent in eliciting neutralizing antibodies than either the AdC7-GP or GP1t alone. Neutralizing antibodies induced by the heterologous prime-boost regimen sustained at high titers for at least 18 weeks after immunization. Significantly, in vivo challenge studies revealed that the entry of reporter EBOV-like particles was efficiently blocked in mice receiving the heterologous prime-boost regimen even at 18 weeks after the final dose of immunization. These results suggest that this novel AdC7-GP prime/GP1t boost regimen represents an EBOV vaccine approach capable of establishing long-term protection, and therefore warrants further development. Copyright © 2017 Elsevier B.V. All rights reserved.

Platinum Nickel Nanowires as Methanol Oxidation Electrocatalysts

DOE PAGES

Alia, Shaun M.; Pylypenko, Svitlana; Neyerlin, Kenneth C.; ...

2015-08-27

We investigated platinum(Pt) nickel (Ni) nanowires (PtNiNWs) as methanol oxidation reaction (MOR) catalysts in rotating disk electrode (RDE) half-cells under acidic conditions. Pt-ruthenium (Ru) nanoparticles have long been the state of the art MOR catalyst for direct methanol fuel cells (DMFCs) where Ru provides oxophilic sites, lowering the potential for carbon monoxide oxidation and the MOR onset. Ru, however, is a precious metal that has long term durability concerns. Ni/Ni oxide species offer a potential to replace Ru in MOR electrocatalysis. PtNiNWs were investigated for MOR and oxygen annealing was investigated as a route to improve catalyst performance (mass activitymore » 65% greater) and stability to potential cycling. Our results presented show that PtNiNWs offer significant promise in the area, but also result in Ni ion leaching that is a concern requiring further evaluation in fuel cells.« less

Immunotherapy in prostate cancer: challenges and opportunities.

PubMed

Noguchi, Masanori; Koga, Noriko; Moriya, Fukuko; Itoh, Kyogo

2016-01-01

Although treatment options for castration-resistant prostate cancer (CRPC) have increased over the last decade, there remains a need for strategies that can provide durable disease control and long-term benefit. Recently, immunotherapy has emerged as a viable and attractive strategy for the treatment of CRPC. To date, there are multiple strategies to target the immune system, and several approaches including therapeutic cancer vaccines and immune checkpoint inhibitors have been most successful in clinical trials. With regard to this, we report the results of the most recent clinical trials investigating immunotherapy in CRPC and discuss the future development of immunotherapy for CRPC, as well as the potential importance of biomarkers in the future progress of this field.

An ultrafine platinum-cobalt alloy decorated cobalt nanowire array with superb activity toward alkaline hydrogen evolution.

PubMed

Wang, Ziqiang; Ren, Xiang; Luo, Yonglan; Wang, Liang; Cui, Guanwei; Xie, Fengyu; Wang, Hongjing; Xie, Ying; Sun, Xuping

2018-06-22

It is highly desired to design and develop highly efficient electrocatalysts for alkaline hydrogen evolution reactions. Herein, we report the development of ultrafine PtCo alloy nanoparticle decorated one-dimensional Co nanowires grown on Ti mesh (PtCo-Co/TiM). Owing to its favorable composition and structure, the PtCo-Co/TiM can deliver an ultrahigh current density of 46.5 mA cm-2 at an overpotential of 70 mV in 1.0 M KOH, superior to recently reported Pt-based electrocatalysts. This catalyst also provides excellent long-term electrochemical durability with its catalytic activity being maintained for at least 50 h.

The changing face of an epidemic: healthy old age with HIV.

PubMed

Nugent, D B; Chowdhury, M; Waters, L J

2017-09-02

The demographics of the HIV epidemic in the UK have changed significantly. Owing to a steady rate of new diagnoses and improved survival, the population of individuals living with HIV continues to increase. HIV is now widely considered to be a chronic condition and HIV-positive individuals are expected to live into old age. Increasing rates of age-related comorbidities challenge HIV care providers to deliver durable viral suppression, ensure long-term adherence to antiretroviral treatment and promote wellbeing into old age. High rates of mental health disorders and social stigma continue to have a negative impact on the quality of life of people living with HIV. Models of care must adapt to this evolving epidemic.

Adapting ethanol fuels to diesel engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

During the 2nd International Alcohol Symposium 1977, Daimler-Benz reported on the advantages and disadvantages of the various methods of using ethanol in originally diesel-operated commercial vehicles, and especially about the first results in the field of adapting the ethanol fuel to the requirements of conventional diesel engines. Investigations to this effect were continued by Daimler-Benz AG, Stuttgart, and Mercedes-Benz of Brasil in coordination with competent Brazilian government departments. The development effort is primarily adapted to Brazilian conditions, since ethanol fuel is intended as a long-term project in this country. This report is presented under headings - auto-ignition; durability tests; remedialmore » measures; the injection systems; ethanol quality.« less

AMTEC cell testing, optimization of rhodium/tungsten electrodes, and tests of other components

NASA Technical Reports Server (NTRS)

Williams, Roger M.; Ryan, Margaret A.; Jeffries-Nakamura, Barbara; Underwood, Mark L.; O'Connor, Dennis; Kikkert, Stan

1991-01-01

Electrodes, current collectors, ceramic to metal braze seals, and metallic components exposed to the high 'hot side' temperatures and sodium liquid and vapor environment have been tested and evaluated in laboratory cells running for hundreds of hours at 1100-1200 K. Rhodium/tungsten electrodes have been selected as the optimum electrodes based on performance parameters and durability. Current collectors have been evaluated under simulated and actual operating conditions. The microscopic effects of metal migration between electrode and current collector alloys as well as their thermal and electrical properties determined the suitability of current collector and lead materials. Braze seals suitable for long term application to AMTEC devices are being developed.

Experimental investigation of RC beams using BOTDA(R)-FRP-OF

NASA Astrophysics Data System (ADS)

Zhou, Zhi; He, Jianping; Huang, Ying; Ou, Jinping

2008-04-01

Brillouin based fiber optic sensing turns to be a promising technology for Structural Health Monitoring (SHM). However, the bare optical fiber is too fragile to act as a practical sensor, so high durability and large range (large strain) Brillouin distributed sensors are in great needs in field applications. For this reason, high durable and large range optical fiber Brillouin Optical Time Domain Analysis (Reflectometer) sensors packaged by Fiber Reinforcement Polymer (FRP), named BOTDA(R)-FRP-OF, have been studied and developed. Besides, in order to study the large strain, crack and slip between the rebar and concrete in reinforced concrete (RC) beams using BOTDR(A) technique, five RC Beams installed with BOTDA(R)-FRP-OF sensors have been set up. And the damage characteristics of the RC beams were investigated by comparing the strain measured by the BOTDA(R)-FRP-OF sensors and the strain from traditional electric strain gauges and Fiber Bragg Grating (FBG) sensors, respectively. The test results show that the BOTDA(R)-FRP-OF sensor can effectively detect the damage (including crack and slip) characteristic of RC beam, and it is suitable for the long-term structural health monitoring on concrete structures such as bridge, big dam and so on.

Study on RC beams using BOTDA(R)-FRP-OF technique

NASA Astrophysics Data System (ADS)

He, Jianping; Zhou, Zhi; Huang, Ying; Ou, Jinping

2008-03-01

Brillouin based fiber optic sensing turns to be a promising technology for Structural Health Monitoring (SHM). However, the bare optical fiber is too fragile to act as a practical sensor, so high durability and large range (large strain) Brillouin distributed sensors are in great needs in field applications. For this reason, high durable and large range optical fiber Brillouin Optical Time Domain Analysis sensors packaged by Fiber Reinforcement Polymer (FRP), named BOTDA(R)-FRP-OF, have been studied and developed. Besides, in order to study the large strain, crack and slip between the rebar and concrete in reinforced concrete (RC) beams using BOTDR(A) technique, two RC Beams installed with BOTDA(R)-FRP-OF sensors have been set up. And the damage characteristics of the RC beams were investigated by comparing the strain measured by the BOTDA(R)-FRP-OF sensors and the strain from traditional electric strain gauges. The test results show that the BOTDA(R)-FRP-OF sensor can effectively detect the damage (including crack and slip) characteristic of RC beam, and it is suitable for the long-term structural health monitoring on concrete structures such as bridge, big dam and so on.

A simple way to an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding property.

PubMed

Ren, Guina; Song, Yuanming; Li, Xiangming; Wang, Bo; Zhou, Yanli; Wang, Yuyan; Ge, Bo; Zhu, Xiaotao

2018-07-15

Development of an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding by a simple method is highly desirable, yet it remains a challenge that current technologies have been unable to fully address. Herein, the original fabric is immersed into the solution containing ZnO nanoparticle and PDMS (polydimethylsiloxane), and the fiber surfaces are uniformly covered by a ZnO-PDMS layer after thermal treatment at 110 °C for 30 min. Droplets of water and corrosive liquids including strong acid, strong alkali, and saturated salt solution display sphere shape on the ZnO-PDMS coated fabric surface. The stable binding of ZnO-PDMS layer onto the fibers allows for the fabric coating with robust superhydrophobicity, and the coated fabric still displays superhydrophobicity after hand twisting, knife scratching, finger touching, and even cycles of sandpaper abrasion. The ZnO-PDMS coated fabric can also keep its superhydrophobic property when exposed to long term UV illumination, demonstrating its UV resistance. Moreover, the uniformly distribution of ZnO nanoparticles on fibers allows the ZnO-PDMS coated fabric to display UV shielding property. Copyright © 2018 Elsevier Inc. All rights reserved.

Cold Climate Foundation Retrofit Experimental Hygrothermal Performance: Cloquet Residential Research Facility Laboratory Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, Louise F.; Harmon, Anna C.

2015-04-01

Thermal and moisture problems in existing basements create a unique challenge because the exterior face of the wall is not easily or inexpensively accessible. This approach addresses thermal and moisture management from the interior face of the wall without disturbing the exterior soil and landscaping. the interior and exterior environments. This approach has the potential for improving durability, comfort, and indoor air quality. This project was funded jointly by the National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory (ORNL). ORNL focused on developing a full basement wall system experimental database to enable others to validate hygrothermal simulation codes.more » NREL focused on testing the moisture durability of practical basement wall interior insulation retrofit solutions for cold climates. The project has produced a physically credible and reliable long-term hygrothermal performance database for retrofit foundation wall insulation systems in zone 6 and 7 climates that are fully compliant with the performance criteria in the 2009 Minnesota Energy Code. The experimental data were configured into a standard format that can be published online and that is compatible with standard commercially available spreadsheet and database software.« less

UV-Resistant and Thermally Stable Superhydrophobic CeO2 Nanotubes with High Water Adhesion.

PubMed

Li, Xue-Ping; Sun, Ya-Li; Xu, Yao-Yi; Chao, Zi-Sheng

2018-06-03

A novel type of sticky superhydrophobic cerium dioxide (CeO 2 ) nanotube material is prepared by hydrothermal treatment without any chemical modification. A water droplet on the material surface shows a static water contact angle of about 157° but the water droplet is pinned on the material surface even when the material surface is turned upside down. Interestingly, the as-prepared CeO 2 nanotube material displays durable superhydrophobicity and enhanced adhesion to water under ultraviolet (UV) light irradiation. Importantly, this change in water adhesion can be reversed by heat treatment to restore the original adhesive value of 20 µL. Further, the maximum volume of the water droplet adhered on the material surface of CeO 2 nanotubes can be regulated without loss of superhydrophobicity during the heating treatment/UV-irradiation cycling. Meanwhile, the superhydrophobic CeO 2 nanotube material shows remarkable thermal stability even at temperatures as high as 450 °C, long-term durability in chemical environment, and air-storage and good resistance to oily contaminant. Finally, the potential application in no-loss water transportation of this sticky superhydrophobic CeO 2 material is demonstrated. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficient Dual-Site Carbon Monoxide Electro-Catalysts via Interfacial Nano-Engineering.

PubMed

Liu, Zhen; Huang, Zhongyuan; Cheng, Feifei; Guo, Zhanhu; Wang, Guangdi; Chen, Xu; Wang, Zhe

2016-09-21

Durable, highly efficient, and economic sound electrocatalysts for CO electrooxidation (COE) are the emerging key for wide variety of energy solutions, especially fuel cells and rechargeable metal-air batteries. Herein, we report the novel system of nickel-aluminum double layered hydroxide (NiAl-LDH) nanoplates on carbon nanotubes (CNTs) network. The formulation of such complexes system was to be induced through the assistance of gold nanoparticles in order to form dual-metal active sites so as to create a extended Au/NiO two phase zone. Bis (trifluoromethylsulfonyl)imide (NTf2) anion of ionic liquid electrolyte was selected to enhance the CO/O2 adsorption and to facilitate electro-catalyzed oxidation of Ni (OH)2 to NiOOH by increasing the electrophilicity of catalytic interface. The resulting neutral catalytic system exhibited ultra-high electrocatalytic activity and stability for CO electrooxidation than commercial and other reported precious metal catalysts. The turnover frequency (TOF) of the LDH-Au/CNTs COE catalyst was much higher than the previous reported other similar electrocatalysts, even close to the activity of solid-gas chemical catalysts at high temperature. Moreover, in the long-term durability testing, the negligible variation of current density remains exsisting after 1000 electrochemistry cycles.

The natural history and treatment outcome of blast phase BCR-ABL− myeloproliferative neoplasms

PubMed Central

Tam, Constantine S.; Nussenzveig, Roberto M.; Popat, Uday; Bueso-Ramos, Carlos E.; Thomas, Deborah A.; Cortes, Jorge A.; Champlin, Richard E.; Ciurea, Stefan E.; Manshouri, Taghi; Pierce, Sherry M.; Kantarjian, Hagop M.

2008-01-01

We analyzed the outcomes of 74 patients diagnosed with BCR-ABL− myeloproliferative neoplasms in blast phase receiving induction chemotherapy (55%), low-intensity therapy (16%), stem cell transplantation (SCT; 3%), or supportive care (26%). Median survival from the date of blastic transformation was 5 months. Patients receiving supportive therapy had a median survival of 6 weeks. Complete remission with or without blood recovery was achieved in 46% of patients receiving induction chemotherapy, but remissions were not durable with a median progression-free survival of only 5 months. Eight patients received SCT either as first therapy or after responding to antileukemia therapy. These patients had a markedly superior survival, with 73% alive at a median follow-up of 31 months. JAK2V617F kinetics were assessed in 16 patients: 0 of 4 negative patients became positive at transformation, and among 12 positive patients, 1 had an increase in JAK2V617F% at transformation, 7 had a substantial decrease, and 4 had stable levels. Myeloproliferative neoplasm blast phase is associated with a dismal prognosis. Responses to chemotherapy can be achieved but are not durable. Long-term survivors had all received SCT either as first therapy or in first remission. PMID:18566326

Radioimmunotherapy for treatment of B-cell lymphomas and other hematologic malignancies.

PubMed

Park, Steven I; Press, Oliver W

2007-11-01

Radioimmunotherapy has emerged as one of the most promising treatment options for hematologic malignancies. This review will present the latest information on radioimmunotherapy for treatment of hematologic malignancies in various clinical settings and assess its long-term safety profile. Recent data suggest that radioimmunotherapy with 131I-tositumomab or 90Y-ibritumomab tiuxetan not only induces high response rates but also results in durable remissions in patients with relapsed or refractory indolent non-Hodgkin's lymphomas. Even more notable response rates have been observed when radioimmunotherapy is used as front-line treatment in patients with indolent non-Hodgkin's lymphomas. The use of radioimmunotherapy has been evaluated in the treatment of aggressive lymphomas with promising results, but it remains investigational. Standard doses of radioimmunotherapy given as a conditioning regimen for hematopoietic stem-cell transplant or myeloablative doses of radioimmunotherapy given in conjunction with stem-cell support have yielded encouraging outcomes with durable remissions and a low incidence of treatment-related mortality. The safety and efficacy of radioimmunotherapy has been demonstrated for patients with B-cell lymphomas and other hematologic malignancies in various clinical settings. A number of randomized phase III clinical trials are currently underway to further define radioimmunotherapy's role in the treatment of lymphomas.

The vexing problem of thrombosis in long-term mechanical circulatory support.

PubMed

Mehra, Mandeep R; Stewart, Garrick C; Uber, Patricia A

2014-01-01

Durable left ventricular assist devices (LVADs) have not only enhanced longevity but also conferred sustained improvements in quality of life, symptom control, and functional capacity in patients with medically refractory advanced heart failure. Problems with device-related infection, bleeding, neurologic events, right-sided heart failure, and device malfunction have dominated the clinical care of patients living on mechanical support. Even as adoption of durable LVADs accelerated globally, we began to encounter a growing dilemma of pump malfunction caused by thrombosis. In early 2011, clinicians began to notice a spike in the incidence of pump thrombosis with the HeartMate II (Thoratec Corp, Pleasanton, CA) LVAD. By 2012, the problem of thrombosis in LVADs began to consume most of the scientific direction as centers and collaborative groups began to dissect this nascent phenomenon. In this perspective, we describe the magnitude and implications of pump thrombosis, discuss secular and management trends in this unique population, attempt to dissect the problem at its root, offer guidance on surveillance and therapeutic principles, and outline issues that deserve our immediate and collaborative attention. © 2014 International Society for Heart and Lung Transplantation Published by International Society for the Heart and Lung Transplantation All rights reserved.

Efficient Dual-Site Carbon Monoxide Electro-Catalysts via Interfacial Nano-Engineering

PubMed Central

Liu, Zhen; Huang, Zhongyuan; Cheng, Feifei; Guo, Zhanhu; Wang, Guangdi; Chen, Xu; Wang, Zhe

2016-01-01

Durable, highly efficient, and economic sound electrocatalysts for CO electrooxidation (COE) are the emerging key for wide variety of energy solutions, especially fuel cells and rechargeable metal−air batteries. Herein, we report the novel system of nickel−aluminum double layered hydroxide (NiAl-LDH) nanoplates on carbon nanotubes (CNTs) network. The formulation of such complexes system was to be induced through the assistance of gold nanoparticles in order to form dual-metal active sites so as to create a extended Au/NiO two phase zone. Bis (trifluoromethylsulfonyl)imide (NTf2) anion of ionic liquid electrolyte was selected to enhance the CO/O2 adsorption and to facilitate electro-catalyzed oxidation of Ni (OH)2 to NiOOH by increasing the electrophilicity of catalytic interface. The resulting neutral catalytic system exhibited ultra-high electrocatalytic activity and stability for CO electrooxidation than commercial and other reported precious metal catalysts. The turnover frequency (TOF) of the LDH-Au/CNTs COE catalyst was much higher than the previous reported other similar electrocatalysts, even close to the activity of solid-gas chemical catalysts at high temperature. Moreover, in the long-term durability testing, the negligible variation of current density remains exsisting after 1000 electrochemistry cycles. PMID:27650532

Efficient Dual-Site Carbon Monoxide Electro-Catalysts via Interfacial Nano-Engineering

NASA Astrophysics Data System (ADS)

Liu, Zhen; Huang, Zhongyuan; Cheng, Feifei; Guo, Zhanhu; Wang, Guangdi; Chen, Xu; Wang, Zhe

2016-09-01

Durable, highly efficient, and economic sound electrocatalysts for CO electrooxidation (COE) are the emerging key for wide variety of energy solutions, especially fuel cells and rechargeable metal-air batteries. Herein, we report the novel system of nickel-aluminum double layered hydroxide (NiAl-LDH) nanoplates on carbon nanotubes (CNTs) network. The formulation of such complexes system was to be induced through the assistance of gold nanoparticles in order to form dual-metal active sites so as to create a extended Au/NiO two phase zone. Bis (trifluoromethylsulfonyl)imide (NTf2) anion of ionic liquid electrolyte was selected to enhance the CO/O2 adsorption and to facilitate electro-catalyzed oxidation of Ni (OH)2 to NiOOH by increasing the electrophilicity of catalytic interface. The resulting neutral catalytic system exhibited ultra-high electrocatalytic activity and stability for CO electrooxidation than commercial and other reported precious metal catalysts. The turnover frequency (TOF) of the LDH-Au/CNTs COE catalyst was much higher than the previous reported other similar electrocatalysts, even close to the activity of solid-gas chemical catalysts at high temperature. Moreover, in the long-term durability testing, the negligible variation of current density remains exsisting after 1000 electrochemistry cycles.

Functional parameter screening for predicting durability of rolling sliding contacts with different surface finishes

NASA Astrophysics Data System (ADS)

Dimkovski, Z.; Lööf, P.-J.; Rosén, B.-G.; Nilsson, P. H.

2018-06-01

The reliability and lifetime of machine elements such as gears and rolling bearings depend on their wear and fatigue resistance. In order to screen the wear and surface damage, three finishing processes: (i) brushing, (ii) manganese phosphating and (iii) shot peening were applied on three disc pairs and long-term tested on a twin-disc tribometer. In this paper, the elastic contact of the disc surfaces (measured after only few revolutions) was simulated and a number of functional and roughness parameters were correlated. The functional parameters consisted of subsurface stresses at different depths and a new parameter called ‘pressure spikes’ factor’. The new parameter is derived from the pressure distribution and takes into account the proximity and magnitude of the pressure spikes. Strong correlations were found among the pressure spikes’ factor and surface peak/height parameters. The orthogonal shear stresses and Von Mises stresses at the shallowest depths under the surface have shown the highest correlations but no good correlations were found when the statistics of the whole stress fields was analyzed. The use of the new parameter offers a fast way to screen the durability of the contacting surfaces operating at similar conditions.

Mn-Doped CaBi4Ti4O15/Pb(Zr,Ti)O3 Ultrasonic Transducers for Continuous Monitoring at Elevated Temperatures

PubMed Central

Kibe, Taiga; Nagata, Hajime

2017-01-01

Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of a CaBi4Ti4O15(CBT)/Pb(Zr,Ti)O3(PZT) sol-gel composite could be one solution for ultrasonic nondestructive testing (NDT) above 500 °C because no couplant is required and CBT has a high Curie temperature. To verify the high temperature durability, CBT/PZT sol-gel composite films were fabricated on titanium substrates by spray coating, and the CBT/PZT samples were tested in a furnace at various temperatures. Reflected echoes with a high signal-to-noise ratio were observed up to 600 °C. A thermal cycle test was conducted from room temperature to 600 °C, and no significant deterioration was found after the second thermal cycle. To investigate the long-term high-temperature durability, a CBT/PZT ultrasonic transducer was tested in the furnace at 600 °C for 36 h. Ultrasonic responses were recorded every 3 h, and the sensitivity and signal-to-noise ratio were stable throughout the experiment. PMID:29186910

Radioactively contaminated electric arc furnace dust as an addition to the immobilization mortar in low- and medium-activity repositories.

PubMed

Castellote, Marta; Menéndez, Esperanza; Andrade, Carmen; Zuloaga, Pablo; Navarro, Mariano; Ordóñez, Manuel

2004-05-15

Electric arc furnace dust (EAFD), generated by the steel-making industry, is in itself an intrinsic hazardous waste; however, the case may also be that scrap used in the process is accidentally contaminated by radioactive elements such as cesium. In this case the resulting EAFD is to be handled as radioactive waste, being duly confined in low- and medium-activity repositories (LMAR). What this paper studies is the reliability of using this radioactive EAFD as an addition in the immobilization mortar of the containers of the LMAR, that is, from the point of view of the durability. Different mixes of mortar containing different percentages of EAFD have been subjected to flexural and compressive strength, initial and final setting time, XRD study, total porosity and pore size distribution, determination of the chloride diffusion coefficient, dimensional stability tests, hydration heat, workability of the fresh mix, and leaching behavior. What is deduced from the results is that for the conditions used in this research, (cement + sand) can be replaced by EAFD upto a ratio [EAFD/(cement + EAFD)] of 46% in the immobilization mortar of LMAR, apparently without any loss in the long-term durability properties of the mortar.

Semiconductor nanostructures for artificial photosynthesis

NASA Astrophysics Data System (ADS)

Yang, Peidong

2012-02-01

Nanowires, with their unique capability to bridge the nanoscopic and macroscopic worlds, have already been demonstrated as important materials for different energy conversion. One emerging and exciting direction is their application for solar to fuel conversion. The generation of fuels by the direct conversion of solar energy in a fully integrated system is an attractive goal, but no such system has been demonstrated that shows the required efficiency, is sufficiently durable, or can be manufactured at reasonable cost. One of the most critical issues in solar water splitting is the development of a suitable photoanode with high efficiency and long-term durability in an aqueous environment. Semiconductor nanowires represent an important class of nanostructure building block for direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. Nanowires can be readily designed and synthesized to deterministically incorporate heterojunctions with improved light absorption, charge separation and vectorial transport. Meanwhile, it is also possible to selectively decorate different oxidation or reduction catalysts onto specific segments of the nanowires to mimic the compartmentalized reactions in natural photosynthesis. In this talk, I will highlight several recent examples in this lab using semiconductor nanowires and their heterostructures for the purpose of direct solar water splitting.

Activation of Molecular Oxygen Using Durable Cobalt Encapsulated with Nitrogen-Doped Graphitic Carbon Shells for Aerobic Oxidation of Lignin-Derived Alcohols.

PubMed

Sun, Yuxia; Ma, Hong; Luo, Yang; Zhang, Shujing; Gao, Jin; Xu, Jie

2018-03-26

It has long been a challenge for activating O 2 by transition-metal nanocatalysts, which might lose activity due to strong tendency for oxidation. Herein, O 2 could be activated by durable encapsulated cobalt nanoparticles (NPs) with N-doped graphitic carbon shells (Co@N-C), but not by encapsulated cobalt NPs with graphitic carbon, exposed cobalt NPs supported on activated carbon, or N-doped carbon. Electron paramagnetic resonance, real-time in situ FTIR spectroscopy, and mass spectrometry measurements demonstrated the generation of the highly active superoxide radical, O 2 .- . This unique ability enables Co@N-C to afford an excellent catalytic performance in model aerobic oxidation of monomeric lignin-derived alcohols. Further analysis elucidated that encapsulated cobalt and nitrogen-doped graphitic carbon might contribute to the capacity through influencing the electronic properties of outer layers. Moreover, through isolation by N-doped graphitic carbon shells, the inner metallic cobalt NPs are inaccessible in term of either alcohols or oxygenated products, and a distinctive resistance to leaching and agglomeration has been achieved. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulation of long-term fatigue damage in bioprosthetic heart valves: effects of leaflet and stent elastic properties

PubMed Central

Martin, Caitlin

2014-01-01

One of the major failure modes of bioprosthetic heart valves (BHVs) is noncalcific structural deterioration due to fatigue of the tissue leaflets; yet, the mechanisms of fatigue are not well understood. BHV durability is primarily assessed based on visual inspection of the leaflets following accelerated wear testing. In this study, we developed a computational framework to simulate BHV leaflet fatigue, which is both efficient and quantitative, making it an attractive alternative to traditional accelerated wear testing. We utilize a phenomenological soft tissue fatigue damage model developed previously to describe the stress softening and permanent set of the glutaraldehyde-treated bovine pericardium leaflets in BHVs subjected to cyclic loading. A parametric study was conducted to determine the effects of altered leaflet and stent elastic properties on the fatigue of the leaflets. The simulation results show that heterogeneity of the leaflet elastic properties, poor leaflet coaptation, and little stent-tip deflection may accelerate leaflet fatigue, which agrees with clinical findings. Therefore, the developed framework may be an invaluable tool for evaluating leaflet durability in new tissue valve designs, including traditional BHVs as well as new transcatheter valves. PMID:24092257

Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

PubMed

Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

2016-05-04

Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

Highly durable polymer electrolyte membranes at elevated temperature: Cross-linked copolymer structure consisting of poly(benzoxazine) and poly(benzimidazole)

NASA Astrophysics Data System (ADS)

Kim, Sung-Kon; Kim, Ki-Hyun; Park, Jung Ock; Kim, Kihyun; Ko, Taeyun; Choi, Seong-Woo; Pak, Chanho; Chang, Hyuk; Lee, Jong-Chan

2013-03-01

For polymer electrolyte membrane fuel cell (PEMFC) applications at elevated temperature (>100 °C), a series of cross-linked benzoxazine-benzimidazole copolymer, P(HFa-co-BI), membranes are prepared by casting a solution of poly[2,2‧-(m-phenylene)-5,5‧-bibenzimidazole] (PBI) and di-functional benzoxazine monomer, 6,6‧-(hexafluoroisopropylidene)bis(3-phenyl-3,4-dihydro-2H-benzoxazine) (HFa), in N,N-dimethylacetamide prior to stepwise heating to 250 °C. The films are also viable to manufacture to large quantities and area by roll-to-roll coating. The resulting cross-linked copolymer, P(HFa-co-BI), membranes are found to be thermally and mechanically stable. Although the proton conductivity values of P(HFa-co-BI) membranes are smaller than that of the PBI membrane, their cell performance (0.68 V at 0.2 A cm-2 at 150 °C) is close to that of PBI membrane and their long-term durability (ca. 3116 cycles on in situ accelerated lifetime mode of load cycling testing) is found to be far superior to the PBI membrane.

Research: Treatment Study to determine the durability of glycaemic control with early treatment with a vildagliptin–metformin combination regimen vs. standard-of-care metformin monotherapy—the VERIFY trial: a randomized double-blind trial

PubMed Central

Del Prato, S; Foley, J E; Kothny, W; Kozlovski, P; Stumvoll, M; Paldánius, P M; Matthews, D R

2014-01-01

Aims Durability of good glycaemic control (HbA1c) is of importance as it can be the foundation for delaying diabetic complications. It has been hypothesized that early initiation of treatment with the combination of oral anti-diabetes agents with complementary mechanisms of action can increase the durability of glycaemic control compared with metformin monotherapy followed by a stepwise addition of oral agents. Dipeptidyl peptidase-4 inhibitors are good candidates for early use as they are efficacious in combination with metformin, show weight neutrality and a low risk of hypoglycaemia. We aimed to test the hypothesis that early combined treatment of metformin and vildagliptin slows β-cell deterioration as measured by HbA1c. Methods Approximately 2000 people with Type 2 diabetes mellitus who were drug-naive or who were treated with metformin for less than 1 month, and who have HbA1c of 48–58 mmol/mol (6.5–7.5%), will be randomized in a 1:1 ratio in VERIFY, a 5-year multinational, double-blind, parallel-group study designed to compare early initiation of a vildagliptin–metformin combination with standard-of-care initiation of metformin monotherapy, followed by the stepwise addition of vildagliptin when glycaemia deteriorates. Further deterioration will be treated with insulin. The primary analysis for treatment failure will be from a Cox proportional hazard regression model and the durability of glycaemic control will be evaluated by assessing treatment failure rate and the rate of loss in glycaemic control over time as co-primary endpoints. Summary VERIFY is the first study to investigate the long-term clinical benefits of early combination treatment vs. the standard-of-care metformin monotherapy with a second agent added by threshold criteria. PMID:24863949

Metallic State FeS Anchored (Fe)/Fe3O4/N-Doped Graphitic Carbon with Porous Spongelike Structure as Durable Catalysts for Enhancing Bioelectricity Generation.

PubMed

Xu, Xin; Dai, Ying; Yu, Jia; Hao, Liang; Duan, Yaqiang; Sun, Ye; Zhang, Yanhong; Lin, Yuhui; Zou, Jinlong

2017-03-29

The critical issues in practical application of microbial fuel cells (MFCs) for wastewater treatment are the high cost and poor activity and durability of precious metal catalysts. To alleviate the activity loss and kinetic barriers for oxygen reduction reaction (ORR) on cathode, (Fe)/Fe 3 O 4 /FeS/N-doped graphitic carbon ((Fe)/Fe 3 O 4 /FeS/NGC) is prepared as ORR catalyst through a one-step method using waste pomelo skins as carbon source. Various characterization techniques and electrochemical analyses are conducted to illustrate the correlation between structural characteristics and catalytic activity. MFCs with Fe/Fe 3 O 4 /FeS/NGC (900 °C) cathode produces the maximum power density of 930 ± 10 mW m -2 (Pt/C of 489 mW m -2 ) and maintains a good long-term durability, which only declines 18% after 90 day operation. Coulombic efficiency (22.2%) obtained by Fe/Fe 3 O 4 /FeS/NGC (900 °C) cathode is significantly higher than that of Pt/C (17.3%). Metallic state FeS anchored in porous NGC skeleton can boost electron transport through the interconnected channels in spongelike structure to improve catalytic activity. Charge delocalization of C atoms can be strengthened by N atoms incorporation into carbon skeleton, which correspondingly contributes to the O 2 chemisorptions and O-O bond weakening during ORR. Energetically existed active components (Fe and N species) are more efficient than Pt to trap and consume electrons in catalyzing ORR in wastewater containing Pt-poisoning substances (bacterial metabolites). (Fe)/Fe 3 O 4 /FeS/NGC catalysts with the advantages of durable power outputs and environmental-friendly raw material can cover the shortages of Pt/C and provide an outlook for further applications of these catalysts.

Durable Complete Response After Discontinuation of Pembrolizumab in Patients With Metastatic Melanoma.

PubMed

Robert, Caroline; Ribas, Antoni; Hamid, Omid; Daud, Adil; Wolchok, Jedd D; Joshua, Anthony M; Hwu, Wen-Jen; Weber, Jeffrey S; Gangadhar, Tara C; Joseph, Richard W; Dronca, Roxana; Patnaik, Amita; Zarour, Hassane; Kefford, Richard; Hersey, Peter; Zhang, Jin; Anderson, James; Diede, Scott J; Ebbinghaus, Scot; Hodi, F Stephen

2017-12-28

Purpose Pembrolizumab provides durable antitumor activity in metastatic melanoma, including complete response (CR) in about 15% of patients. Data are limited on potential predictors of CR and patient disposition after pembrolizumab discontinuation after CR. We describe baseline characteristics and long-term follow-up in patients who experienced CR with pembrolizumab in the KEYNOTE-001 study ( ClinicalTrials.gov identifier: NCT01295827). Patients and Methods Patients with ipilimumab-naive or -treated advanced/metastatic melanoma received one of three dose regimens of pembrolizumab. Eligible patients who received pembrolizumab for ≥ 6 months and at least two treatments beyond confirmed CR could discontinue therapy. Response was assessed every 12 weeks by central Response Evaluation Criteria in Solid Tumors version 1.1. For this analysis, CR was defined per investigator assessment, immune-related response criteria, and potential predictors of CR were evaluated using univariate and multivariate analyses. Results Of 655 treated patients, 105 (16.0%) achieved CR after median follow-up of 43 months. At data cutoff, 92 patients (87.6%) had CR, with median follow-up of 30 months from first CR. Fourteen (13.3%) patients continued to receive treatment for a median of ≥ 40 months. Pembrolizumab was discontinued by 91 patients (86.7%), including 67 (63.8%) who proceeded to observation without additional anticancer therapy. The 24-month disease-free survival rate from time of CR was 90.9% in all 105 patients with CR and 89.9% in the 67 patients who discontinued pembrolizumab after CR for observation. Tumor size and programmed death-ligand 1 status were among the baseline factors independently associated with CR by univariate analysis. Conclusion Patients with metastatic melanoma can have durable complete remission after discontinuation of pembrolizumab, and the low incidence of relapse after median follow-up of approximately 2 years from discontinuation provides hope for a cure for some patients. The mechanisms underlying durable CR require further investigation.

Adjuvant-specific regulation of long-term antibody responses by ZBTB20

PubMed Central

Wang, Yinan

2014-01-01

The duration of antibody production by long-lived plasma cells varies with the type of immunization, but the basis for these differences is unknown. We demonstrate that plasma cells formed in response to the same immunogen engage distinct survival programs depending on the adjuvant. After alum-adjuvanted immunization, antigen-specific bone marrow plasma cells deficient in the transcription factor ZBTB20 failed to accumulate over time, leading to a progressive loss of antibody production relative to wild-type controls. Fetal liver reconstitution experiments demonstrated that the requirement for ZBTB20 was B cell intrinsic. No defects were observed in germinal center numbers, affinity maturation, or plasma cell formation or proliferation in ZBTB20-deficient chimeras. However, ZBTB20-deficient plasma cells expressed reduced levels of MCL1 relative to wild-type controls, and transgenic expression of BCL2 increased serum antibody titers. These data indicate a role for ZBTB20 in promoting survival in plasma cells. Strikingly, adjuvants that activate TLR2 and TLR4 restored long-term antibody production in ZBTB20-deficient chimeras through the induction of compensatory survival programs in plasma cells. Thus, distinct lifespans are imprinted in plasma cells as they are formed, depending on the primary activation conditions. The durability of vaccines may accordingly be improved through the selection of appropriate adjuvants. PMID:24711582

Bridge condition assessment based on long-term strain monitoring

NASA Astrophysics Data System (ADS)

Sun, LiMin; Sun, Shouwang

2011-04-01

In consideration of the important role that bridges play as transportation infrastructures, their safety, durability and serviceability have always been deeply concerned. Structural Health Monitoring Systems (SHMS) have been installed to many long-span bridges to provide bridge engineers with the information needed in making rational decisions for maintenance. However, SHMS also confronted bridge engineers with the challenge of efficient use of monitoring data. Thus, methodologies which are robust to random disturbance and sensitive to damage become a subject on which many researches in structural condition assessment concentrate. In this study, an innovative probabilistic approach for condition assessment of bridge structures was proposed on the basis of long-term strain monitoring on steel girder of a cable-stayed bridge. First, the methodology of damage detection in the vicinity of monitoring point using strain-based indices was investigated. Then, the composition of strain response of bridge under operational loads was analyzed. Thirdly, the influence of temperature and wind on strains was eliminated and thus strain fluctuation under vehicle loads is obtained. Finally, damage evolution assessment was carried out based on the statistical characteristics of rain-flow cycles derived from the strain fluctuation under vehicle loads. The research conducted indicates that the methodology proposed is qualified for structural condition assessment so far as the following respects are concerned: (a) capability of revealing structural deterioration; (b) immunity to the influence of environmental variation; (c) adaptability to the random characteristic exhibited by long-term monitoring data. Further examination of the applicability of the proposed methodology in aging bridge may provide a more convincing validation.

Design of electrochromic window technology with single and multi-color patterns

NASA Astrophysics Data System (ADS)

Kim, Sooyeun

The electrochromic window (ECW) technology has gained a lot of attention due to its current and potential applications for office, vehicle and aircraft windows. Center for Intelligent Materials and System (CIMS) at University of Washington has proposed the new design of an ECW for its high contrast, rapid switching speed and long cyclic lifetime. Three primary components of the ECW are an electrochromic (EC) layer, an ion conducting layer and an ion storage layer. A V2O5-TiO2 (V/Ti=70/30) film, fabricated by a sol-gel electrophoretic deposition, was proposed as an ion storage layer. The film was characterized by X-ray diffraction, a scanning probe microscope and impedance spectroscopy. Its optical and electrochemical properties were investigated. The poly-(3,3-dimethy1-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) film was suggested as an EC layer. Its electropolymerization kinetics and optical and electrochemical properties were reported. The V2O 5-TiO2 film based ECW was successfully fabricated and examined. The ECW exhibited its high electrochromic contrast, rapid switching speed and long-term cyclic durability. Its contrast (Delta%T = Tmax-T min) was 68%T with a minimum transmittance of 1% at 580 nm wavelength. The ECW took five seconds for complete coloration, while it did four seconds for complete bleaching. Its asymmetric switching behavior was explained by modeling the ECW as a simple equivalent circuit. The cyclic durability of the ECW was measured over 150,000 cycles. It revealed the contrast degradation of only 2% at 580 nm wavelength. The ECW dimensions were scaled up to 300 x 300 mm2, demonstrating their high contrast and long-term electrochemical cycle stability. Multi-color pattern electrochromic window technology was considered to evolve toward higher definition devices. Patterning of electrodes was essential to fabricate multi-color pattern ECWs which required the separation of adjacent electrodes. New fabrication procedures to create a pattern electrode were challenged. Two monomers were selectively electropolymerized on the pattern electrode in order to display a set of colors. The successful construction of a two-color pattern ECW was based on the sandwich-type configuration.

Efficacy and durability of the chimney graft technique in urgent and complex thoracic endovascular aortic repair.

PubMed

Bin Jabr, Adel; Lindblad, Bengt; Dias, Nuno; Resch, Timothy; Malina, Martin

2015-04-01

This study reports the early and midterm to long-term experience of chimney grafts (CGs) in urgent endovascular repair of complex lesions in the thoracic aorta. Twenty-nine high-risk patients (20 men) who were unfit for open repair were treated using CG technique for ruptured (n = 14) or symptomatic (n = 15) aortic lesions engaging the aortic arch itself (n = 9), the descending aorta (n = 10), or the thoracoabdominal aorta (n = 10). Twenty-two patients (76%) were treated urgently (≤24 hours) and seven were semiurgent (≤3 days). Of 41 chimneys used, 24 were placed in supra-aortic branches and 17 in visceral branches. Median follow-up (interquartile range) for the entire cohort was 2 years (0.6-3.8 years), 2.5 years (1-4 years) for 30-day survivors, and 3.5 years (1.9-6.4 years) for those who were still alive. Four patients (14%) died ≤30 days of cerebral infarction (n = 1), visceral ischemia secondary to the initial rupture (n = 1), multiple organ failure (n = 1), or heart failure (n = 1). There were 11 late deaths (38%); however, only two deaths were related to the CG technique. The primary and secondary technical success rates were 86% (25 of 29) and 97% (28 of 29), respectively. The secondary patency rate of CGs was 98%. Seventeen (68%) of the aortic lesions shrank significantly. Three patients (10%) had primary type I endoleak and another three (10%) had secondary type I endoleak. The endoleaks were managed with Onyx (ev3 Endovascular, Inc, Plymouth, Minn) or coil embolization (n = 2), restenting (n = 1), and conversion to open repair (n = 2). One secondary endoleak is still under observation after >20 months. All primary endoleaks and one secondary endoleak originated from CGs in the brachiocephalic trunk (4 of 6 [67%]). The midterm to long-term results of the CG technique for urgent and complex lesions of the thoracic aorta in high-risk patients are promising, with low early mortality and long durability of the CGs. More patients with longer follow-up are still needed. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Three-year follow-up of treatment-naïve and previously treated patients with CLL and SLL receiving single-agent ibrutinib.

PubMed

Byrd, John C; Furman, Richard R; Coutre, Steven E; Burger, Jan A; Blum, Kristie A; Coleman, Morton; Wierda, William G; Jones, Jeffrey A; Zhao, Weiqiang; Heerema, Nyla A; Johnson, Amy J; Shaw, Yun; Bilotti, Elizabeth; Zhou, Cathy; James, Danelle F; O'Brien, Susan

2015-04-16

Ibrutinib is an orally administered inhibitor of Bruton tyrosine kinase that antagonizes B-cell receptor, chemokine, and integrin-mediated signaling. In early-phase studies, ibrutinib demonstrated high response rates and prolonged progression-free survival (PFS) in chronic lymphocytic leukemia (CLL). The durable responses observed with ibrutinib relate in part to a modest toxicity profile that allows the majority of patients to receive continuous therapy for an extended period. We report on median 3-year follow-up of 132 patients with symptomatic treatment-naïve and relapsed/refractory CLL or small lymphocytic lymphoma. Longer treatment with ibrutinib was associated with improvement in response quality over time and durable remissions. Toxicity with longer follow-up diminished with respect to occurrence of grade 3 or greater cytopenias, fatigue, and infections. Progression remains uncommon, occurring primarily in some patients with relapsed del(17)(p13.1) and/or del(11)(q22.3) disease. Treatment-related lymphocytosis remains largely asymptomatic even when persisting >1 year and does not appear to alter longer-term PFS and overall survival compared with patients with partial response or better. Collectively, these data provide evidence that ibrutinib controls CLL disease manifestations and is well tolerated for an extended period; this information can help direct potential treatment options for different subgroups to diminish the long-term risk of relapse. © 2015 by The American Society of Hematology.

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

The future of mechanical circulatory support for advanced heart failure.

PubMed

Marinescu, Karolina K; Uriel, Nir; Adatya, Sirtaz

2016-05-01

Mechanical circulatory support (MCS) has become the main focus of heart replacement therapy for end stage heart failure patients. Advances in technology are moving towards miniaturization, biventricular support devices, complete internalization, improved hemocompatibility profiles, and responsiveness to cardiac loading conditions. This review will discuss the recent advances and investigational devices in MCS for advanced heart failure. The demand for both short-term and long-term durable devices for advanced heart failure is increasing. The current devices are still fraught with an unacceptably high incidence of gastrointestinal bleeding and thromboembolic and infectious complications. New devices are on the horizon focusing on miniaturization, versatility for biventricular support, improved hemocompatibility, use of alternate energy sources, and incorporation of continuous hemodynamic monitoring. The role for MCS in advanced heart replacement therapy is steadily increasing. With the advent of newer generation devices on the horizon, the potential exists for MCS to surpass heart transplantation as the primary therapy for advanced heart failure.

The orientation construction of S and N dual-doped discoid-like graphene with high-rate electrode property

NASA Astrophysics Data System (ADS)

Song, Xinyu; Ma, Xinlong; Ning, Guoqing; Gao, Daowei; Yu, Zhiqing; Xiao, Zhihua

2018-06-01

The orientation construction of S and N dual-doped discoid-like graphene (labeled as SNDG) is achieved by regular arrangement of the polycyclic aromatics in pitch molecules using natural diatomites as templates. The superior electrochemical energy storage ability of SNDG is demonstrated by cathode and anode tests, respectively. The synergistic effects of the robust scaffold coupled with the hollow structure, unique porous structure, the excellent structural stability and the dual-doping of S and N lead to the electrode property enhancement in terms of rate capability and durability. The Li ion hybrid capacitor using SNDG as both anode and cathode, presents excellent long-term cycling stability and markedly energy and power densities (up to 143 Wh kg-1 and 13,548 W kg-1). This work provides a novel pathway to realize the mass production of high-rate electrode materials via the high value-added utilization of pitch.

NDE of polymeric composite material bridge components

NASA Astrophysics Data System (ADS)

Duke, John C., Jr.; Horne, Michael R.

1998-03-01

Rapid advancements with respect to utilization of polymeric composite materials for bridge components is occurring. This situation is driven primarily by the potential improvements offered by these materials with respect to long term durability. However, because of the developmental nature of these materials much of the materials characterization has involved short term testing without the synergistic effects of environmental exposure. Efforts to develop nondestructive evaluation procedures, essential for any wide spread use in critical structural applications, have been consequently limited. This paper discuses the effort to develop NDE methods for field inspection of hybrid glass and carbon fiber reinforced vinyl ester pultruded 'double box' I beams that are installed in a small bridge over Tom's Creek, in Blacksburg, Virginia. Integrated structural element sensors, dormant infrared devices, as well as acousto-ultrasonic methods are under development for detecting and monitoring the occurrence and progression of life limiting deterioration mechanisms.

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

Influence of degradation conditions on dentin bonding durability of three universal adhesives.

PubMed

Sai, Keiichi; Shimamura, Yutaka; Takamizawa, Toshiki; Tsujimoto, Akimasa; Imai, Arisa; Endo, Hajime; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2016-11-01

This study aims to determine dentin bonding durability of universal adhesives using shear bond strength (SBS) tests under various degradation conditions. G-Premio Bond (GP, GC), Scotchbond Universal (SU, 3M ESPE) and All Bond Universal (AB, Bisco) were compared with conventional two-step self-etch adhesive Clearfil SE Bond (SE, Kuraray Noritake Dental). Bonded specimens were divided into three groups of ten, and SBSs with bovine dentin were determined after the following treatments: 1) Storage in distilled water at 37°C for 24h followed by 3000, 10,000, 20,000 or 30,000 thermal cycles (TC group), 2) Storage in distilled water at 37°C for 3 months, 6 months or 1year (water storage, WS group) and 3) Storage in distilled water at 37°C for 24h (control). SE bonded specimens showed significantly higher SBSs than universal adhesives, regardless of TC or storage periods, although AB specimens showed significantly increased SBSs after 30,000 thermal cycles. In comparisons of universal adhesives under control and degradation conditions, SBS was only reduced in SU after 1year of WS. Following exposure of various adhesive systems to degradation conditions of thermal cycling and long term storage, SBS values of adhesive systems varied primarily with degradation period. Although universal adhesives have lower SBSs than the two-step self-etch adhesive SE, the present data indicate that the dentin bonding durability of universal adhesives in self-etch mode is sufficient for clinical use. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thymopericardial augmented encasement for coronary artery bypass graft surgery: a report of 245 cases.

PubMed

Ohtsuka, Toshiya; Ninomiya, Mikio; Nonaka, Takahiro

2009-07-01

: A pedicled prepericardial fat flap was created to augment the pericardial cavity and applied for patients undergoing coronary artery bypass grafting. The efficacy and durability of this method were investigated. : Between July 2005 and November 2008, the present technique was applied for consecutive 245 patients (165 men and 80 women, aged 67 ± 8.3 years) undergoing isolated coronary artery bypass grafting in which 240 (98.0%) were off-pump cases. The left and/or right internal thoracic artery and the gastroepiploic artery were used in 244 and 160 patients, respectively, and the saphenous vein and the radial artery were used in 51 and 10 patients, respectively. Ninety-seven (40.0%) patients had been diabetic, 18 (7.3%) had had chronic renal failure, and three were redo cases. The prepericardial soft tissue, involving the pedicled thymic gland, was dissected en bloc and sewn with pericardiotomies to wrap the heart and the grafts. Angiography or three-dimensional computed tomography was used to assess the intrapericardial pathways of each graft and a long-term durability of the fat pad. : Early angiography or three-dimensional computed tomography proved that the graft pathways were unaffected by the encasements. Resternotomies in two patients and sternal treatments for infectious dehiscence in two patients were safely achievable. Five-year postoperative computed tomography showed the intact fat pad in the retrosternal space. : The present technique can encase the heart not the least jeopardizing each pathway of the grafts, and the durable fat pad functions protectively when the sternotomy is either reopened or infected.

Development of Oxidation Protection Coatings for Gamma Titanium Aluminide Alloys

NASA Technical Reports Server (NTRS)

Wallace, T. A.; Bird, R. K.; Sankaran, S. N.

2003-01-01

Metallic material systems play a key role in meeting the stringent weight and durability requirements for reusable launch vehicle (RLV) airframe hot structures. Gamma titanium aluminides (gamma-TiAl) have been identified as high-payoff materials for high-temperature applications. The low density and good elevated temperature mechanical properties of gamma-TiAl alloys make them attractive candidates for durable lightweight hot structure and thermal protection systems at temperatures as high as 871 C. However, oxidation significantly degrades gamma-TiAl alloys under the high-temperature service conditions associated with the RLV operating environment. This paper discusses ongoing efforts at NASA Langley Research Center to develop durable ultrathin coatings for protecting gamma-TiAl alloys from high-temperature oxidation environments. In addition to offering oxidation protection, these multifunctional coatings are being engineered to provide thermal control features to help minimize heat input into the hot structures. This paper describes the coating development effort and discusses the effects of long-term high-temperature exposures on the microstructure of coated and uncoated gamma-TiAl alloys. The alloy of primary consideration was the Plansee alloy gamma-Met, but limited studies of the newer alloy gamma-Met-PX were also included. The oxidation behavior of the uncoated materials was evaluated over the temperature range of 704 C to 871 C. Sol-gel-based coatings were applied to the gamma-TiAl samples by dipping and spraying, and the performance evaluated at 871 C. Results showed that the coatings improve the oxidation resistance, but that further development is necessary.

Dual Tuning of Ni-Co-A (A = P, Se, O) Nanosheets by Anion Substitution and Holey Engineering for Efficient Hydrogen Evolution.

PubMed

Fang, Zhiwei; Peng, Lele; Qian, Yumin; Zhang, Xiao; Xie, Yujun; Cha, Judy J; Yu, Guihua

2018-04-18

Seeking earth-abundant electrocatalysts with high efficiency and durability has become the frontier of energy conversion research. Mixed-transition-metal (MTM)-based electrocatalysts, owing to the desirable electrical conductivity, synergistic effect of bimetal atoms, and structural stability, have recently emerged as new-generation hydrogen evolution reaction (HER) electrocatalysts. However, the correlation between anion species and their intrinsic electrocatalytic properties in MTM-based electrocatalysts is still not well understood. Here we present a novel approach to tuning the anion-dependent electrocatalytic characteristics in MTM-based catalyst for HER, using holey Ni/Co-based phosphides/selenides/oxides (Ni-Co-A, A = P, Se, O) as the model materials. The electrochemical results, combined with the electrical conductivity measurement and DFT calculation, reveal that P substitution could modulate the electron configuration, lower the hydrogen adsorption energy, and facilitate the desorption of hydrogen on the active sites in Ni-Co-A holey nanostructures, resulting in superior HER catalytic activity. Accordingly we fabricate the NCP holey nanosheet electrocatalyst for HER with an ultralow onset overpotential of nearly zero, an overpotential of 58 mV, and long-term durability, along with an applied potential of 1.56 V to boost overall water splitting at 10 mA cm -2 , among the best electrocatalysts reported for non-noble-metal catalysts to date. This work not only presents a deeper understanding of the intrinsic HER electrocatalytic properties for MTM-based electrocatalyst with various anion species but also offers new insights to better design efficient and durable water-splitting electrocatalysts.

Fixed or mobile-bearing total knee arthroplasty

PubMed Central

Huang, Chun-Hsiung; Liau, Jiann-Jong; Cheng, Cheng-Kung

2007-01-01

Fixed and mobile-bearing in total knee arthroplasty are still discussed controversially. In this article, biomechanical and clinical aspects in both fixed and mobile-bearing designs were reviewed. In biomechanical aspect, the mobile-bearing design has proved to provide less tibiofemoral contact stresses under tibiofemoral malalignment conditions. It also provides less wear rate in in-vitro simulator test. Patients with posterior stabilized mobile-bearing knees had more axial tibiofemoral rotation than patients with posterior stabilized fixed-bearing knees during gait as well as in a deep knee-bend activity. However, in clinical aspect, the mid-term or long-term survivorship of mobile-bearing knees has no superiority over that of fixed-bearing knees. The theoretical advantages for mobile-bearing design to provide a long-term durability have not been demonstrated by any outcome studies. Finally, the fixed-bearing design with all-polyethylene tibial component is suggested for relatively inactive, elder people. The mobile-bearing design is suggested for younger or higher-demand patients due to the potential for reduced polyethylene wear and more normal kinematics response after joint replacement. For younger surgeon, the fixed-bearing design is suggested due to less demand for surgical technique. For experienced surgeon, one familiar surgical protocol and instrumentation is suggested rather than implant design, either fixed-bearing or mobile-bearing. PMID:17204165

Fixed or mobile-bearing total knee arthroplasty.

PubMed

Huang, Chun-Hsiung; Liau, Jiann-Jong; Cheng, Cheng-Kung

2007-01-05

Fixed and mobile-bearing in total knee arthroplasty are still discussed controversially. In this article, biomechanical and clinical aspects in both fixed and mobile-bearing designs were reviewed. In biomechanical aspect, the mobile-bearing design has proved to provide less tibiofemoral contact stresses under tibiofemoral malalignment conditions. It also provides less wear rate in in-vitro simulator test. Patients with posterior stabilized mobile-bearing knees had more axial tibiofemoral rotation than patients with posterior stabilized fixed-bearing knees during gait as well as in a deep knee-bend activity. However, in clinical aspect, the mid-term or long-term survivorship of mobile-bearing knees has no superiority over that of fixed-bearing knees. The theoretical advantages for mobile-bearing design to provide a long-term durability have not been demonstrated by any outcome studies. Finally, the fixed-bearing design with all-polyethylene tibial component is suggested for relatively inactive, elder people. The mobile-bearing design is suggested for younger or higher-demand patients due to the potential for reduced polyethylene wear and more normal kinematics response after joint replacement. For younger surgeon, the fixed-bearing design is suggested due to less demand for surgical technique. For experienced surgeon, one familiar surgical protocol and instrumentation is suggested rather than implant design, either fixed-bearing or mobile-bearing.

SiC Field Effect Transistor Technology Demonstrating Prolonged Stable Operation at 500 C

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.; Spry, David J.; Chen, Liang-Yu; Okojie, Robert S.; Beheim, Glenn M.; Meredith, Roger; Ferrier, Terry

2006-01-01

While there have been numerous reports of short-term transistor operation at 500 degree C or above, these devices have previously not demonstrated sufficient long-term operational durability at 500 degree C to be considered viable for most envisioned applications. This paper reports the development of Silicone Carbi field effect transistors capable of long-term electrical operation at 500 degree C. A 6H-SiC MESFET was packaged and subjected to continuous electrical operation while residing in a 500 degree C oven in oxidizing air atmosphere for over 2400 hours. The transistor gain, saturation current (IDSS), and on-resistance (RDS) changed by less than 20% from initial values throughout the duration of the biased 500 degree C test. Another high-temperature packaged 6H-SiC MESFET was employed to form a simple one-stage high-temperature low-frequency voltage amplifier. This single-stage common-source amplifier demonstrated stable continuous electrical operation (negligible changes to gain and operating biases) for over 600 hours while residing in a 500 degree C air ambient oven. In both cases, increased leakage from annealing of the Schottky gate-to-channel diode was the dominant transistor degradation mechanism that limited the duration of 500 degree C electrical operation.

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.

2016-02-22

The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors.more » Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

NASA Astrophysics Data System (ADS)

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; Barnett, Scott A.; Wang, Jun

2016-02-01

The coarsening of Ni in Ni-yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.

Ketamine alters cortical integration of GABAergic interneurons and induces long-term sex-dependent impairments in transgenic Gad67-GFP mice.

PubMed

Aligny, C; Roux, C; Dourmap, N; Ramdani, Y; Do-Rego, J-C; Jégou, S; Leroux, P; Leroux-Nicollet, I; Marret, S; Gonzalez, B J

2014-07-03

Ketamine, a non-competitive N-methyl-D-aspartate (NMDA) antagonist, widely used as an anesthetic in neonatal pediatrics, is also an illicit drug named Super K or KitKat consumed by teens and young adults. In the immature brain, despite several studies indicating that NMDA antagonists are neuroprotective against excitotoxic injuries, there is more and more evidence indicating that these molecules exert a deleterious effect by suppressing a trophic function of glutamate. In the present study, we show using Gad67-GFP mice that prenatal exposure to ketamine during a time-window in which GABAergic precursors are migrating results in (i) strong apoptotic death in the ganglionic eminences and along the migratory routes of GABAergic interneurons; (ii) long-term deficits in interneuron density, dendrite numbers and spine morphology; (iii) a sex-dependent deregulation of γ-aminobutyric acid (GABA) levels and GABA transporter expression; (iv) sex-dependent changes in the response to glutamate-induced calcium mobilization; and (v) the long-term sex-dependent behavioral impairment of locomotor activity. In conclusion, using a preclinical approach, the present study shows that ketamine exposure during cortical maturation durably affects the integration of GABAergic interneurons by reducing their survival and differentiation. The resulting molecular, morphological and functional modifications are associated with sex-specific behavioral deficits in adults. In light of the present data, it appears that in humans, ketamine could be deleterious for the development of the brain of preterm neonates and fetuses of addicted pregnant women.

Design, development, and first in vivo results of an implantable ventricular assist device, MicroVad.

PubMed

Kerkhoffs, Wolfgang; Schumacher, Oliver; Meyns, Bart; Verbeken, Erik; Leunens, Veerle; Bollen, Hilde; Reul, Helmut

2004-10-01

The design concept and first in vitro and in vivo results of a long-term implantable ventricular assist device system based on a microaxial blood pump are presented. The blood-immersed parts of the pump consist of a single-stage impeller and a proximally integrated microelectric motor. Both parts are surrounded by a pump housing currently made of polycarbonate to allow visible access to the blood-exposed parts. A titanium inflow cage attached to the tip of the housing is directly implanted into the left ventricular apex. The outflow of the pump is connected to the descending aorta by means of an e-PTFE graft. The overall dimensions of the device are 12 mm in outer diameter and about 50 mm in length. The calculated lifetime of the device is up to 2 years. The system underwent long-term durability tests, hydraulic performance tests, dynamic stability tests, and in vitro hemolysis and thrombogenicity tests. Furthermore, animal tests have been performed in adult Dorset sheep. In a first series, the pump has been placed extracorporeally; in a second series, the pump was completely implanted. Mean duration of the animal experiments of the second series was 31 days (range 8-110 days, n=14); no anticoagulation was administered over the whole test period. Blood data revealed no significant changes in blood cell counts, ionogram, or any other value. No end-organ dysfunction induced by long-term support could be observed, nor did the pathology reveal any evidence of thromboembolic complications.

A stretchable strain sensor based on a metal nanoparticle thin film for human motion detection

NASA Astrophysics Data System (ADS)

Lee, Jaehwan; Kim, Sanghyeok; Lee, Jinjae; Yang, Daejong; Park, Byong Chon; Ryu, Seunghwa; Park, Inkyu

2014-09-01

Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response speed and mechanical robustness.Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response speed and mechanical robustness. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03295k

Recent progress in the development of Terumo implantable left ventricular assist system.

PubMed

Nojiri, C; Kijima, T; Maekawa, J; Horiuchi, K; Kido, T; Sugiyama, T; Mori, T; Sugiura, N; Asada, T; Shimane, H; Ozaki, T; Suzuki, M; Akamatsu, T; Akutsu, T

1999-01-01

The research group of the Terumo Corporation, the NTN Corporation, and Setsunan University (T. Akamatsu) has been developing an implantable left ventricular assist system (ILVAS) featuring a centrifugal blood pump with a magnetically suspended impeller (MSCP). The impeller of the MSCP is suspended by a magnetic bearing, providing contact-free rotation of the impeller inside the pump housing. Thus the MSCP is expected to provide years of long-term durability. Ex vivo chronic sheep experiments using the extracorporeal model (Model I) demonstrated long-term durability, nonthrombogenicity, and a low hemolysis rate (plasma free Hb <6 mg/dl) for more than 2 years. The prototype implantable model (Model II; 196 ml, 400 g) was evaluated ex vivo in 2 sheep and intrathoracically implanted in a small sheep (45 kg). These experiments were terminated at 70, 79, and 17 days, respectively, because of blood leakage through the connector system within the housing of Model II. There was no thrombus formation on the retrieved pump surfaces. A new connector system was introduced to the Model II pump (modified Model II), and the pump was intrathoracically implanted in a sheep. Pump flow rate was maintained at 3-7 L/min at 1700-1800 rpm. The temperature elevation on the surfaces of the motor and the electromagnet inside the pump casing was kept less than 6 degrees C. The temperature of the tissue adjacent to the pump casing became normal 10 days postoperatively. The sheep survived for more than 5 months without any sign of mechanical failure or thromboembolic complication. In vitro real-time endurance tests of motor bearings made of stainless steel and silicone nitride have been conducted for more than 1 year without any sign of bearing wear. The next prototype system (Model III), with an implantable controller and a new MSCP with reduced input power, has been developed with a view toward a totally implantable LVAS.

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence.

PubMed

Wang, Liang; Liu, Zhanzhong; Dai, Shiyun; Yan, Jiawei; Wise, Michael J

2017-01-01

The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald's (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data.

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence

PubMed Central

Wang, Liang; Liu, Zhanzhong; Dai, Shiyun; Yan, Jiawei; Wise, Michael J.

2017-01-01

The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald’s (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data. PMID:29209284

Effect of process variables on the quality characteristics of pelleted wheat distiller's dried grains with solubles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaya Shankar Tumuluru; Lope Tabil; Anthony Opoku

2011-04-01

The rapid expansion of ethanol processing plants in Canada has resulted in a significant increase in the production of wheat-based distiller's dried grains with solubles (DDGS). Transportation and flowability problems associated with DDGS necessitate investigations on pelleting. In the present study, the effect of process variables like die temperature (T) and feed moisture content (Mw) on the pellet properties like pellet moisture content, durability and pellet density was explored using a single pelleting machine; further studies on pelleting DDGS using a pilot-scale pellet mill were also conducted to understand the effect of die diameter and steam conditioning on durability andmore » bulk density of pellets. Proximate analysis of DDGS indicated that crude protein and dry matter were in the range of 37.37–40.33% and 91.27–92.60%, respectively. Linear regression models developed for pellet quality attributes like pellet moisture content, pellet density and durability adequately described the single pelleting process with R2 value of 0.97, 0.99 and 0.7, respectively. ANOVA results have indicated that linear terms T and Mw and the interaction term T × Mw were statistically significant at P < 0.01 and P < 0.1 for pellet moisture content and pellet density. Based on the trends of the surface plots, a medium T of about 50–80 °C and a low Mw of about 5.1% resulted in maximum pellet density and durability and minimum pellet moisture content. Results from pilot-scale studies indicated that bulk density, durability and throughput values were 436.8–528.9 kg m-3, 60.3–92.7% and 45.52–68.77 kg h-1, respectively. It was observed that both die diameter and steam addition had a significant effect on the bulk density and the durability values. The highest bulk density and durability were achieved with 6.4 mm die diameter with steam addition compared to 7.9 mm die with or without steam addition.« less

Plasma soluble factor following two decades prolonged suppressive antiretroviral therapy in HIV-1-positive males: A cross-sectional study.

PubMed

Sperk, Maike; Zhang, Wang; Nowak, Piotr; Neogi, Ujjwal

2018-02-01

Acute human immunodeficiency virus (HIV) infection is associated with a marked induction of several pathways that are linked to inflammation and CD4 T-cell depletion. Many of these processes do not fully resolve on short-term combination antiretroviral therapy (cART) (<5 years), despite complete and durable suppression of viremia. The effects of long-term (>15 years) successful antiretroviral therapy (ART) and the linkage between levels of biomarkers remain unclear. Therefore, the present study aims to assess the host plasma proteome in a well-defined clinical material from HIV-1-positive male patients on successful long-term ART (>15 years) and compared them with age-matched healthy controls and treatment-naïve male patients with viremia in a cross-sectional manner.Plasma samples were obtained from 3 categories of age-matched HIV-1-positive male patients on long-term successfully (ART, n = 10) with a median (Interquartile range, IQR) of 19 (17-20) years, treatment-naïve patients with viremia (VP, n = 14), and HIV-1-negative persons (HC, n = 11). Plasma proteome was analyzed using the proximity extension assay targeting 92 factors. Statistical analyses were performed with GraphPad Prism v7, R-packages, and Qlucore Omics Explorer v3.2. Functional enrichment analysis was performed by Kyoto Encyclopedia of Genes and Genomes (KEGG), and interactions of specific molecules were identified using Path Designer integrated into Ingenuity Pathway Analysis (IPA).Group wise comparison identified 53 soluble factors, which differed between the groups (P < .05). Cluster analysis identified 13 discrete soluble factors (CD8A, CRTAM, CXCL13, EGF, CD5, CD40, CXCL9, Gal-1, IL12RB1, KLRD1, PD-1, CASP-8 and TNFRSF9) between the studied groups (adjusted P < .001). The long-term successfully ART-treated individuals clustered and networked with the HC while VPs clustered separately. All of the proinflammatory cytokines and chemokines were normalized back to levels of healthy controls in long-term successfully ART-treated individuals, but not the levels of KLRD1 and PGDFB.sKLRD1 that is involved in the regulation of natural killer cell (NK) mediated cytotoxicity, failed to be restored to the level of HIV-negative individuals despite successful long-term ART. Additional analysis of NK cells along with T-cell subsets can provide insights into the long-term effects of ART on the immune system.

Transoral incisionless fundoplication: current status.

PubMed

Sami Trad, Karim

2016-07-01

Transoral incisionless fundoplication (TIF) performed with the EsophyX device (Redmond, Washington, USA) is a totally endoscopic procedure with the objectives to mechanically repair a defective gastroesophageal valve and to reduce small hiatal hernias. The recent publication of randomized controlled trials and long-term follow-up data offers the opportunity to reevaluate this treatment modality and its role in the management of patients with chronic gastroesophageal reflux disease (GERD). Randomized controlled trials have confirmed the ability of TIF to eliminate troublesome GERD symptoms, heal esophagitis, and improve distal esophageal acid exposure in appropriately selected patient populations. These studies establish TIF's superiority to conventional medical therapy, especially in clinical scenarios where proton-pump inhibitors fail to provide complete symptom relief across the spectrum of classic and atypical GERD manifestations, including regurgitation and laryngopharyngeal reflux. Long-term data indicate sustained positive outcomes and durability up to 6 years after procedure. These results were achieved with a low rate of serious adverse events and usually without introducing troublesome dysphagia, gas bloat, or flatulence. Based on the most recent data, TIF appears to be a valuable treatment alternative for the management of appropriately selected patients with moderate to severe chronic GERD symptoms.

NASA PS304 Lubricant Tested in World's First Commercial Oil-Free Gas Turbine

NASA Technical Reports Server (NTRS)

Weaver, Harold F.

2003-01-01

In a marriage of research and commercial technology, a 30-kW Oil-Free Capstone microturbine electrical generator unit has been installed and is serving as a test bed for long-term life-cycle testing of NASA-developed PS304 shaft coatings. The coatings are used to reduce friction and wear of the turbine engine s foil air bearings during startup and shut down when sliding occurs, prior to the formation of a lubricating air film. This testing supports NASA Glenn Research Center s effort to develop Oil-Free gas turbine aircraft propulsion systems, which will employ advanced foil air bearings and NASA s PS304 high temperature solid lubricant to replace the ball bearings and lubricating oil found in conventional engines. Glenn s Oil-Free Turbomachinery team s current project is the demonstration of an Oil-Free business jet engine. In anticipation of future flight certification of Oil-Free aircraft engines, long-term endurance and durability tests are being conducted in a relevant gas turbine environment using the Capstone microturbine engine. By operating the engine now, valuable performance data for PS304 shaft coatings and for industry s foil air bearings are being accumulated.

Systemic isotretinoin therapy normalizes exaggerated TLR-2-mediated innate immune responses in acne patients

PubMed Central

Dispenza, Melanie C.; Wolpert, Ellen B.; Gilliland, Kathryn L.; Dai, Pingqi; Cong, Zhaoyuan; Nelson, Amanda M.; Thiboutot, Diane M.

2012-01-01

Retinoids are used in the treatment of inflammatory skin diseases and malignancies, but studies characterizing the in vivo actions of these drugs in humans are lacking. Isotretinoin is a pro-drug for all-trans retinoic acid that can induce long-term remissions of acne; however, its complete mechanism of action is unknown. We hypothesized that isotretinoin induces remission of acne by normalizing the innate immune response to the commensal bacterium P. acnes. Compared to normal subjects, peripheral blood monocytes from acne patients expressed significantly higher levels of TLR-2 and exhibited significantly greater induction of TLR-2 expression following P. acnes stimulation. Treatment of patients with isotretinoin significantly decreased monocyte TLR-2 expression and subsequent inflammatory cytokine response to P. acnes by one week of therapy. This effect was sustained six months following cessation of therapy, indicating that TLR-2 modulation may be involved in the durable therapeutic response to isotretinoin. This study demonstrates that isotretinoin exerts immunomodulatory effects in patients and sheds light on a potential mechanism for its long-term effects in acne. The modulation of TLR-2 expression on monocytes has important implications in other inflammatory disorders characterized by TLR-2 dysregulation. PMID:22513780

Pulmonary Arteriovenous Malformations After the Superior Cavopulmonary Shunt: Mechanisms and Clinical Implications

PubMed Central

Kavarana, Minoo N.; Jones, Jeffrey A.; Stroud, Robert E.; Bradley, Scott M.; Ikonomidis, John S.; Mukherjee, Rupak

2015-01-01

Children with functional single ventricle heart disease are commonly palliated down a staged clinical pathway toward a Fontan completion procedure (total cavopulmonary connection). The Fontan physiology is fraught with long term complications associated with lower body systemic venous hypertension, eventually resulting in significant morbidity and mortality. The bidirectional Glenn shunt or superior cavopulmonary connection (SCPC) is commonly the transitional stage in single ventricle surgical management and provides excellent palliation. Some studies have demonstrated lower morbidity and mortality with the SCPC when compared with the Fontan. Unfortunately the durability of the SCPC is significantly limited by the development of pulmonary arteriovenous malformations (PAVMs) which have been commonly attributed to the absence of hepatic venous blood flow and the lack of pulsatile flow to the affected lungs. Abnormal angiogenesis has been suggested as a final common pathway to PAVM development. Understanding these fundamental mechanisms through the investigation of angiogenic pathways associated with the pathogenesis of PAVMs would help to develop medical therapies that could prevent or reverse this complication following SCPC. Such therapies could improve the longevity of the SCPC, potentially eliminate or significantly postpone the Fontan completion with its associated complications, and improve long-term survival in children with single ventricle disease. PMID:24758411

Bonding to oxide ceramics—laboratory testing versus clinical outcome.

PubMed

Kern, Matthias

2015-01-01

Despite a huge number of published laboratory bonding studies on dental oxide ceramics clinical long-term studies on resin bonded oxide ceramic restorations are rare. The purpose of this review is to present the best available clinical evidence for successful bonding of dental oxide ceramic restorations. Clinical trials with resin-bonded restorations that had no or only limited mechanical retention and were made from alumina or zirconia ceramic were identified using an electronic search in PubMed database. Overall 10 publications with clinical trials could be identified. Their clinical outcome was compared with that laboratory bond strength studies. Clinical data provide strong evidence that air-abrasion at a moderate pressure in combination with using phosphate monomer containing primers and/or luting resins provide long-term durable bonding to glass-infiltrated alumina and zirconia ceramic under the humid and stressful oral conditions. As simple and clinically reliable bonding methods to oxide ceramics exist, the rationale for development of alternative bonding methods might be reconsidered especially when these methods are more time consuming or require rather complicated and/or technique sensitive procedures. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Integrated approach to modeling long-term durability of concrete engineered barriers in LLRW disposal facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J.H.; Roy, D.M.; Mann, B.

1995-12-31

This paper describes an integrated approach to developing a predictive computer model for long-term performance of concrete engineered barriers utilized in LLRW and ILRW disposal facilities. The model development concept consists of three major modeling schemes: hydration modeling of the binder phase, pore solution speciation, and transport modeling in the concrete barrier and service environment. Although still in its inception, the model development approach demonstrated that the chemical and physical properties of complex cementitious materials and their interactions with service environments can be described quantitatively. Applying the integrated model development approach to modeling alkali (Na and K) leaching from amore » concrete pad barrier in an above-grade tumulus disposal unit, it is predicted that, in a near-surface land disposal facility where water infiltration through the facility is normally minimal, the alkalis control the pore solution pH of the concrete barriers for much longer than most previous concrete barrier degradation studies assumed. The results also imply that a highly alkaline condition created by the alkali leaching will result in alteration of the soil mineralogy in the vicinity of the disposal facility.« less

Impact of selective posterior rhizotomy on fine motor skills. Long-term results using a validated evaluative measure.

PubMed

Mittal, Sandeep; Farmer, Jean-Pierre; Al-Atassi, Borhan; Montpetit, Kathleen; Gervais, Nathalie; Poulin, Chantal; Cantin, Marie-André; Benaroch, Thierry E

2002-03-01

Suprasegmental effects following selective posterior rhizotomy have been frequently reported. However, few studies have used validated functional outcome measures to report the surgical results beyond 3 years. The authors analyzed data obtained from the McGill Rhizotomy Database to determine the long-term impact of lumbosacral dorsal rhizotomy on fine motor skills. The study population comprised children with debilitating spasticity who underwent SPR and were evaluated by a multidisciplinary team preoperatively, at 6 months and 1 year postoperatively. Quantitative standardized assessments of upper extremity function were obtained using the fine motor skills section of the Peabody Developmental Motor Scales (PDMS) test. Of 70 patients who met the entry criteria for the study, 45 and 25 completed the 3- and 5-year assessments, respectively. Statistical analysis demonstrated significant improvements in grasping, hand use, eye-hand coordination, and manual dexterity at 1 year after SPR. More importantly, all improvements were maintained at 3 and 5 years following SPR. This study supports that significant improvements in upper extremity fine motor function using the PDMS evaluative measure are present after SPR and that these suprasegmental benefits are durable. Copyright 2002 S. Karger AG, Basel

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, while the growth rates exhibit a Laplace distribution. Large price deviations from the mean price are also governed by a Laplace distribution (fat tails). These results are in agreement with empirical findings. The explicit comparison of the time evolution of consumer durables with empirical investigations confirms the close relationship between price decline and Gompertz diffusion, while the product life cycle can be described qualitatively for a long time period.