Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

NASA Astrophysics Data System (ADS)

Gabb, Timothy P.; Gayda, John; Garg, Anita

2007-01-01

Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy® X, Inconel® 617, Inconel® 740, Nimonic® 263, Incoloy® MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, john; Garg, Anita

2007-01-01

Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy(Registered TradeMark) X, Inconel(Registered TradeMark) 617, Inconel(Registered TradeMark) 740, Nimonic(Registered TradeMark) 263, Incoloy(Registered TradeMark) MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

Stability testing on typical flavonoid containing herbal drugs.

PubMed

Heigl, D; Franz, G

2003-12-01

The aim of the presented work was to examine possible changes in the flavonoid pattern of common flavonoid containing herbal drugs during long term and stress testing storage periods. HPLC fingerprint was used to demonstrate the differences in stability of individual flavonoid components. In addition, the total flavonoid content was determined according to the pharmacopoeial photometrical method. Drug material was stored according to the ICH-guidelines at 25 degrees C and 60% rh (relative humidity) for long term testing over a 24 months period or at 40 degrees C and 75% rh under stress conditions for 6 months. Increased temperatures of 80 degrees C and 100 degrees C were chosen to elucidate possible instabilities of selected flavonoids. As an overall result, during long term testing, no significant changes in the flavonoid pattern can be detected. However, some flavonoid containing herbal drugs (e.g. birch leaves), showed a decrease of most flavonoids when stored at high temperature by an increase in the respective aglycones. Similar results were obtained during storage at 40 degrees C/75% rh.

Long-term effects of steroid withdrawal in kidney transplantation.

PubMed

Offermann, G; Schwarz, A; Krause, P H

1993-01-01

The long-term graft function after withdrawal of steroids from maintenance immunosuppression was analyzed in 98 kidney recipients (59 on cyclosporin monotherapy, 39 on cyclosporin plus azathioprine) who had not developed an early rejection episode when prednisolone was discontinued. Seven years after steroid withdrawal the probability of an increase in serum creatinine (> 20% of baseline levels) was 51%. The increase in creatinine was associated with sclerosing arteriopathy as a marker of chronic rejection in 29 of 43 graft biopsies. The addition of azathioprine had no effect on the stability of long-term graft function and did not influence the 7-year graft survival rate in this highly selected group of patients.

Long term flight electrodes

NASA Technical Reports Server (NTRS)

Mosier, B.

1975-01-01

The reproducibility, stability, and methods of preparation for the various types and forms of biomedical electrodes are discussed. A critical and selective compilation of information on biological and/or physiological electrodes is presented. A discussion of plant hydrocolloids, clays, hydrophyllic colloids, synthetic waxes, and acrylic polymers is included.

Reduced Kalman Filters for Clock Ensembles

NASA Technical Reports Server (NTRS)

Greenhall, Charles A.

2011-01-01

This paper summarizes the author's work ontimescales based on Kalman filters that act upon the clock comparisons. The natural Kalman timescale algorithm tends to optimize long-term timescale stability at the expense of short-term stability. By subjecting each post-measurement error covariance matrix to a non-transparent reduction operation, one obtains corrected clocks with improved short-term stability and little sacrifice of long-term stability.

Ternary rare earth-lanthanide sulfides

DOEpatents

Takeshita, Takuo; Gschneidner JR., Karl A.; Beaudry, Bernard J.

1987-01-06

A new ternary rare earth sulfur compound having the formula: where M is a rare earth element selected from the group europium, samarium and ytterbium and x=0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000.degree. C.

Intraindividual stability of cortisol and cortisone and the ratio of cortisol to cortisone in saliva, urine and hair.

PubMed

Zhang, Quan; Chen, Zheng; Chen, Shenghuo; Xu, Youyun; Deng, Huihua

2017-02-01

Cortisol, cortisone and the ratio of cortisol to cortisone in saliva, urine and hair are acute, short-term and long-term biomarkers to reliably assess the activity of hypothalamic-pituitary-adrenal (HPA) axis and 11β-hydroxysteroid dehydrogenase (11β-HSD). One key issue is whether these biomarkers have intraindividual relative stability. Salivary, urinary and hair cortisol was proven to show considerable long-term intraindividual relative stability. However, currently unknown is whether cortisone and the ratio in saliva, urine and hair show intraindividual relative stability. The present study utilized a longitudinal design to validate long-term stability within two weeks of three biomarkers in saliva and urine, and long-term stability within twelve months of three hair biomarkers. Salivary, urinary and hair steroids were measured with high performance liquid chromatography tandem mass spectrometry. Three biomarkers in urine and hair showed moderate test-retest correlations with coefficient (r) ranging between 0.22 and 0.56 and good multiple-test consistencies with coefficient of intraclass correlation (ICC) ranging between 0.42 and 0.67. Three single-point salivary biomarkers showed weak to moderate test-retest correlations (r's between 0.01 and 0.38) and poor to fair multiple-test consistencies (ICC's between 0.29 and 0.53) within two weeks. Three single-day salivary biomarkers showed moderate test-retest correlations (r's between 0.23 and 0.53) and good multiple-test consistencies (ICC's between 0.56 and 0.66) within two weeks. Three biomarkers in urine and hair showed moderate long-term intraindividual relative stability. Three single-point salivary biomarkers showed weak to moderate short-term and long-term intraindividual relative stability, but three single-day salivary biomarkers showed moderate short-term and long-term intraindividual relative stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Unprecedented long-term frequency stability with a microwave resonator oscillator.

PubMed

Grop, Serge; Schafer, Wolfgang; Bourgeois, Pierre-Yves; Kersale, Yann; Oxborrow, Mark; Rubiola, Enrico; Giordano, Vincent

2011-08-01

This article reports on the long-term frequency stability characterization of a new type of cryogenic sapphire oscillator using an autonomous pulse-tube cryocooler as its cold source. This new design enables a relative frequency stability of better than 4.5 x 10(-15) over one day of integration. To the best of our knowledge, this represents the best long-term frequency stability ever obtained with a signal source based on a macroscopic resonator.

General Investigation of Tidal Inlets: Stability of Selected United States Tidal Inlets

DTIC Science & Technology

1991-09-01

characteristics in relation to the variability of the hydr; aulic parameters. An inlet can fall into any of four "stability" classes 48 Orientation Parameter 80...nlot he ~ :Ke(: t 93. If a fairly straight coast with uniform offshore slopes and a regionally homogeneous wave climate is considered, a reasonable...expectation is LhaL the longshore transport quantities and directions are homogeneous. Given a long-term variability in wave climate , a corresponding

Promoting Healthy Weight with "Stability Skills First": A Randomized Trial

ERIC Educational Resources Information Center

Kiernan, Michaela; Brown, Susan D.; Schoffman, Danielle E.; Lee, Katherine; King, Abby C.; Taylor, C. Barr; Schleicher, Nina C.; Perri, Michael G.

2013-01-01

Objective: Although behavioral weight-loss interventions produce short-term weight loss, long-term maintenance remains elusive. This randomized trial examined whether learning a novel set of "stability skills" before losing weight improved long-term weight management. Stability skills were designed to optimize individuals' current…

One- and two-stage Arrhenius models for pharmaceutical shelf life prediction.

PubMed

Fan, Zhewen; Zhang, Lanju

2015-01-01

One of the most challenging aspects of the pharmaceutical development is the demonstration and estimation of chemical stability. It is imperative that pharmaceutical products be stable for two or more years. Long-term stability studies are required to support such shelf life claim at registration. However, during drug development to facilitate formulation and dosage form selection, an accelerated stability study with stressed storage condition is preferred to quickly obtain a good prediction of shelf life under ambient storage conditions. Such a prediction typically uses Arrhenius equation that describes relationship between degradation rate and temperature (and humidity). Existing methods usually rely on the assumption of normality of the errors. In addition, shelf life projection is usually based on confidence band of a regression line. However, the coverage probability of a method is often overlooked or under-reported. In this paper, we introduce two nonparametric bootstrap procedures for shelf life estimation based on accelerated stability testing, and compare them with a one-stage nonlinear Arrhenius prediction model. Our simulation results demonstrate that one-stage nonlinear Arrhenius method has significant lower coverage than nominal levels. Our bootstrap method gave better coverage and led to a shelf life prediction closer to that based on long-term stability data.

Cation exchange properties of zeolites in hyper alkaline aqueous media.

PubMed

Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

2015-02-03

Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

High somatic distress with high long-term stability in selected patients with chronic depression: a 3-year follow-up of ratings with Karolinska Scales of Personality (KSP).

PubMed

Gardner, Ann; Hällström, Tore

2004-01-01

The main aim of the present study was to investigate mean levels and long-term stability of three scales from the Karolinska Scales of Personality (KSP), assessing somatic components of anxiety proneness in selected patients with chronic depressive symptoms. The KSP was filled in by 84 patients (26 men and 58 women) with a history of or ongoing major depression and audiological, or other comorbid somatic, symptoms. Mean scores for the Somatic Anxiety, Muscular Tension and Psychasthenia scales were above two standard deviations compared to a normative group sampled from the population. The KSP was filled in at follow-up by 65 patients. The mean interval between the ratings was 3.5 years. Comparisons between the ratings of the three scales revealed no significant mean score differences, and quite high individual stability. The mean scores were significantly increased in comparisons with depressed patients in primary care suggesting that these patients with chronic depression may comprise a depressive sub-type characterized by high "somatic distress". A putative origin for the high and stable scores in the presented sub-group of depressed patients, and the concept of "personality trait" in use even for pronounced symptoms, are discussed.

Long term stability following genioplasty: a cephalometric study.

PubMed

Kumar, B Lakshman; Raju, G Kranthi Praveen; Kumar, N Dilip; Reddy, G Vivek; Naik, B Ravindra; Achary, C Ravindranath

2015-04-01

A receding chin associated with an orthognathic mandible is a common situation and surgical changes in chin position are often required to improve the overall harmony of the face. Genioplasty is one such procedure. Stability of hard and soft tissue changes following genioplasty on a long term basis needs to be assessed. Studies on the stability of hard and soft tissue changes following genioplasty on a short term basis have revealed it as a procedure with good stability. This study is done to assess the stability of hard and soft tissue changes following genioplasty on a long term basis. Pre-surgical, postsurgical and long term post-surgical cephalograms of 15 cases treated by vertical reduction augmentation genioplasty were obtained. Paired t-test was used to compare the changes between pre-surgical, postsurgical and long term postsurgical cephalograms. Findings of this study demonstrated that genioplasty is a stable procedure. After long term follow-up period, there was a relapse of 1.5 mm at the pogonion accounting for 24% of the surgical advancement. This is attributed to the remodeling that occurs at the surgical site, but not the instability due to the surgical procedure. With the present study, it can be concluded that vertical reduction and advancement genioplasty can be considered as an adjunctive procedure that produces predictable results and the bony and soft tissue stability were generally very good.

Long Term Stability Following Genioplasty: A Cephalometric Study

PubMed Central

Kumar, B Lakshman; Raju, G Kranthi Praveen; Kumar, N Dilip; Reddy, G Vivek; Naik, B Ravindra; Achary, C Ravindranath

2015-01-01

Background: A receding chin associated with an orthognathic mandible is a common situation and surgical changes in chin position are often required to improve the overall harmony of the face. Genioplasty is one such procedure. Stability of hard and soft tissue changes following genioplasty on a long term basis needs to be assessed. Studies on the stability of hard and soft tissue changes following genioplasty on a short term basis have revealed it as a procedure with good stability. This study is done to assess the stability of hard and soft tissue changes following genioplasty on a long term basis. Materials and Methods: Pre-surgical, postsurgical and long term post-surgical cephalograms of 15 cases treated by vertical reduction augmentation genioplasty were obtained. Paired t-test was used to compare the changes between pre-surgical, postsurgical and long term postsurgical cephalograms. Results: Findings of this study demonstrated that genioplasty is a stable procedure. After long term follow-up period, there was a relapse of 1.5 mm at the pogonion accounting for 24% of the surgical advancement. This is attributed to the remodeling that occurs at the surgical site, but not the instability due to the surgical procedure. Conclusion: With the present study, it can be concluded that vertical reduction and advancement genioplasty can be considered as an adjunctive procedure that produces predictable results and the bony and soft tissue stability were generally very good. PMID:25954070

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.

Stability and predictors of change in salivary cortisol measures over six years: MESA.

PubMed

Wang, Xu; Sánchez, Brisa N; Golden, Sherita Hill; Shrager, Sandi; Kirschbaum, Clemens; Karlamangla, Arun S; Seeman, Teresa E; Roux, Ana V Diez

2014-11-01

A major challenge in characterizing features of the daily cortisol curve is variability in features over time. Few studies have examined the stability of daily features of the cortisol curve over long periods or the predictors of long term changes. Repeated salivary cortisol measures on 580 adults from the MESA Stress study were used to examine the stability of various features of the daily cortisol curve (wakeup value, the cortisol awakening response (CAR), the early and late decline slope and the area under the curve (AUC)), over short periods (several days) and long periods (approximately 6-years) and to investigate the association of demographic factors with the changes. Intraclass correlation coefficients (ICCs) were used to estimate the short and long term stability. Piecewise linear mixed models were used to assess factors associated with changes in features over time. For most features, short term stability (ICCs: 0.17-0.74) was higher than long term stability (ICCs: 0.05-0.42), and long term stability was highest when several days were averaged for each time point. The decline over the day showed the highest long term stability: when several days for each wave were averaged the stability of the daily decline slope across 6 years was similar (or higher) than the stability across short periods. AUC had high stability over short periods (ICCs: 0.65-0.74) but much lower stability across long periods (ICC: 0.05). All features of daily cortisol curve investigated changed significantly over the approximately 6 year follow-up period. The wakeup cortisol became higher; the CAR became smaller; both the early and late decline became flatter; and the AUC became larger. Hispanics experienced significantly larger increases in the wakeup value; and African-Americans and Hispanics showed less flattening over time of the early decline slope than Non-Hispanic Whites. Our findings have implications for characterization of features in studies linking cortisol to health outcomes. The presence of variability over time suggests opportunities for future investigation of the predictors of changes over time as well as the links between these changes and health outcomes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Genes under weaker stabilizing selection increase network evolvability and rapid regulatory adaptation to an environmental shift.

PubMed

Laarits, T; Bordalo, P; Lemos, B

2016-08-01

Regulatory networks play a central role in the modulation of gene expression, the control of cellular differentiation, and the emergence of complex phenotypes. Regulatory networks could constrain or facilitate evolutionary adaptation in gene expression levels. Here, we model the adaptation of regulatory networks and gene expression levels to a shift in the environment that alters the optimal expression level of a single gene. Our analyses show signatures of natural selection on regulatory networks that both constrain and facilitate rapid evolution of gene expression level towards new optima. The analyses are interpreted from the standpoint of neutral expectations and illustrate the challenge to making inferences about network adaptation. Furthermore, we examine the consequence of variable stabilizing selection across genes on the strength and direction of interactions in regulatory networks and in their subsequent adaptation. We observe that directional selection on a highly constrained gene previously under strong stabilizing selection was more efficient when the gene was embedded within a network of partners under relaxed stabilizing selection pressure. The observation leads to the expectation that evolutionarily resilient regulatory networks will contain optimal ratios of genes whose expression is under weak and strong stabilizing selection. Altogether, our results suggest that the variable strengths of stabilizing selection across genes within regulatory networks might itself contribute to the long-term adaptation of complex phenotypes. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Performance and Long-Term Stability of Pd/PSS and Pd/Al2O3 Membranes for Hydrogen Separation

PubMed Central

Liguori, Simona; Iulianelli, Adolfo; Dalena, Francesco; Pinacci, Pietro; Drago, Francesca; Broglia, Maria; Huang, Yan; Basile, Angelo

2014-01-01

The present work is focused on the investigation of the performance and long-term stability of two composite palladium membranes under different operating conditions. One membrane (Pd/porous stainless steel (PSS)) is characterized by a ~10 µm-thick palladium layer on a porous stainless steel substrate, which is pretreated by means of surface modification and oxidation; the other membrane (Pd/Al2O3) is constituted by a ~7 µm-thick palladium layer on an asymmetric microporous Al2O3 substrate. The operating temperature and pressure ranges, used for studying the performance of these two kinds of membranes, are 350–450 °C and 200–800 kPa, respectively. The H2 permeances and the H2/N2 selectivities of both membranes were investigated and compared with literature data. At 400 °C and 200 kPa as pressure difference, Pd/PSS and Pd/Al2O3 membranes exhibited an H2/N2 ideal selectivity equal to 11700 and 6200, respectively, showing stability for 600 h. Thereafter, H2/N2 selectivity of both membranes progressively decreased and after around 2000 h, dropped dramatically to 55 and 310 for the Pd/PSS and Pd/Al2O3 membranes, respectively. As evidenced by Scanning Electron Microscope (SEM) analyses, the pinholes appear on the whole surface of the Pd/PSS membrane and this is probably due to release of sulphur from the graphite seal rings. PMID:24957126

[Stabilization and long-term effect of chromium contaminated soil].

PubMed

Wang, Jing; Luo, Qi-Shi; Zhang, Chang-Bo; Tan, Liang; Li, Xu

2013-10-01

Short-term (3 d and 28 d) and long-term (1 a) stabilization effects of Cr contaminated soil were investigated through nature curing, using four amendments including ferrous sulfide, ferrous sulfate, zero-valent iron and sodium dithionite. The results indicated that ferrous sulfide and zero-valent iron were not helpful for the stabilization of Cr(VI) when directly used because of their poor solubility and immobility. Ferrous sulfate could effectively and rapidly decrease total leaching Cr and Cr(VI) content. The stabilization effect was further promoted by the generation of iron hydroxides after long-term curing. Sodium dithionite also had positive effect on soil stabilization. Appropriate addition ratio of the two chemicals could help maintain the soil pH in range of 6-8.

Long-Term Stability of Oxide Nanowire Sensors via Heavily Doped Oxide Contact.

PubMed

Zeng, Hao; Takahashi, Tsunaki; Kanai, Masaki; Zhang, Guozhu; He, Yong; Nagashima, Kazuki; Yanagida, Takeshi

2017-12-22

Long-term stability of a chemical sensor is an essential quality for long-term collection of data related to exhaled breath, environmental air, and other sources in the Internet of things (IoT) era. Although an oxide nanowire sensor has shown great potential as a chemical sensor, the long-term stability of sensitivity has not been realized yet due to electrical degradation under harsh sensing conditions. Here, we report a rational concept to accomplish long-term electrical stability of metal oxide nanowire sensors via introduction of a heavily doped metal oxide contact layer. Antimony-doped SnO 2 (ATO) contacts on SnO 2 nanowires show much more stable and lower electrical contact resistance than conventional Ti contacts for high temperature (200 °C) conditions, which are required to operate chemical sensors. The stable and low contact resistance of ATO was confirmed for at least 1960 h under 200 °C in open air. This heavily doped oxide contact enables us to realize the long-term stability of SnO 2 nanowire sensors while maintaining the sensitivity for both NO 2 gas and light (photo) detections. The applicability of our method is confirmed for sensors on a flexible polyethylene naphthalate (PEN) substrate. Since the proposed fundamental concept can be applied to various oxide nanostructures, it will give a foundation for designing long-term stable oxide nanomaterial-based IoT sensors.

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

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

Mao, Chengyu; Wood, Marissa; David, Lamuel Abraham

Here, most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commercially-available natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differencesmore » with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells.« less

Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries

DOE PAGES

Mao, Chengyu; Wood, Marissa; David, Lamuel Abraham; ...

2018-06-16

Here, most lithium-ion batteries still rely on intercalation-type graphite materials for anodes, so it is important to consider their role in full cells for applications in electric vehicles. Here, we systematically evaluate the chemical and physical properties of six commercially-available natural and synthetic graphites to establish which factors have the greatest impact on the cycling stability of full cells with nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Electrochemical data and post-mortem characterization explain the origin of capacity fade. The NMC811 cathode shows large irreversible capacity loss and impedance growth, accounting for much of full cell degradation. However, six graphite anodes demonstrate significant differencesmore » with respect to structural change, surface area, impedance growth, and SEI chemistry, which impact overall capacity retention. We found long cycle life correlated most strongly with stable graphite crystallite size. In addition, graphites with lower surface area generally had higher coulombic efficiencies during formation cycles, which led to more stable long-term cycling. The best graphite screened here enables a capacity retention around 90% in full pouch cells over extensive long-term cycling compared to only 82% for cells with the lowest performing graphite. The results show that optimal graphite selection improves cycling stability of high energy lithium-ion cells.« less

Cementless Hydroxyapatite Coated Hip Prostheses

PubMed Central

Herrera, Antonio; Mateo, Jesús; Gil-Albarova, Jorge; Lobo-Escolar, Antonio; Ibarz, Elena; Gabarre, Sergio; Más, Yolanda

2015-01-01

More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality. PMID:25802848

C60 as an Efficient n-Type Compact Layer in Perovskite Solar Cells.

PubMed

Wojciechowski, Konrad; Leijtens, Tomas; Siprova, Svetlana; Schlueter, Christoph; Hörantner, Maximilian T; Wang, Jacob Tse-Wei; Li, Chang-Zhi; Jen, Alex K-Y; Lee, Tien-Lin; Snaith, Henry J

2015-06-18

Organic-inorganic halide perovskite solar cells have rapidly evolved over the last 3 years. There are still a number of issues and open questions related to the perovskite material, such as the phenomenon of anomalous hysteresis in current-voltage characteristics and long-term stability of the devices. In this work, we focus on the electron selective contact in the perovskite solar cells and physical processes occurring at that heterojunction. We developed efficient devices by replacing the commonly employed TiO2 compact layer with fullerene C60 in a regular n-i-p architecture. Detailed spectroscopic characterization allows us to present further insight into the nature of photocurrent hysteresis and charge extraction limitations arising at the n-type contact in a standard device. Furthermore, we show preliminary stability data of perovskite solar cells under working conditions, suggesting that an n-type organic charge collection layer can increase the long-term performance.

Cross Validation of Selection of Variables in Multiple Regression.

DTIC Science & Technology

1979-12-01

55 vii CROSS VALIDATION OF SELECTION OF VARIABLES IN MULTIPLE REGRESSION I Introduction Background Long term DoD planning gcals...028545024 .31109000 BF * SS - .008700618 .0471961 Constant - .70977903 85.146786 55 had adequate predictive capabilities; the other two models (the...71ZCO F111D Control 54 73EGO FlIID Computer, General Purpose 55 73EPO FII1D Converter-Multiplexer 56 73HAO flllD Stabilizer Platform 57 73HCO F1ID

Long-lived groupers require structurally stable reefs in the face of repeated climate change disturbances

NASA Astrophysics Data System (ADS)

Karkarey, R.; Kelkar, N.; Lobo, A. Savio; Alcoverro, T.; Arthur, R.

2014-06-01

Benthic recovery from climate-related disturbances does not always warrant a commensurate functional recovery for reef-associated fish communities. Here, we examine the distribution of benthic groupers (family Serranidae) in coral reef communities from the Lakshadweep archipelago (Arabian Sea) in response to structural complexity and long-term habitat stability. These coral reefs that have been subject to two major El Niño Southern Oscillation-related coral bleaching events in the last decades (1998 and 2010). First, we employ a long-term (12-yr) benthic-monitoring dataset to track habitat structural stability at twelve reef sites in the archipelago. Structural stability of reefs was strongly driven by exposure to monsoon storms and depth, which made deeper and more sheltered reefs on the eastern aspect more stable than the more exposed (western) and shallower reefs. We surveyed groupers (species richness, abundance, biomass) in 60 sites across the entire archipelago, representing both exposures and depths. Sites were selected along a gradient of structural complexity from very low to high. Grouper biomass appeared to vary with habitat stability with significant differences between depth and exposure; sheltered deep reefs had a higher grouper biomass than either sheltered shallow or exposed (deep and shallow) reefs. Species richness and abundance showed similar (though not significant) trends. More interestingly, average grouper biomass increased exponentially with structural complexity, but only at the sheltered deep (high stability) sites, despite the availability of recovered structure at exposed deep and shallow sites (lower-stability sites). This trend was especially pronounced for long-lived groupers (life span >10 yrs). These results suggest that long-lived groupers may prefer temporally stable reefs, independent of the local availability of habitat structure. In reefs subject to repeated disturbances, the presence of structurally stable reefs may be critical as refuges for functionally important, long-lived species like groupers.

Ternary rare earth-lanthanide sulfides

DOEpatents

Takeshita, Takuo; Gschneidner, Jr., Karl A.; Beaudry, Bernard J.

1987-01-06

A new ternary rare earth sulfur compound having the formula: La.sub.3-x M.sub.x S.sub.4 where M is a rare earth element selected from the group europium, samarium and ytterbium and x=0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000.degree. C.

Stability-based sorting: The forgotten process behind (not only) biological evolution.

PubMed

Toman, Jan; Flegr, Jaroslav

2017-12-21

Natural selection is considered to be the main process that drives biological evolution. It requires selected entities to originate dependent upon one another by the means of reproduction or copying, and for the progeny to inherit the qualities of their ancestors. However, natural selection is a manifestation of a more general persistence principle, whose temporal consequences we propose to name "stability-based sorting" (SBS). Sorting based on static stability, i.e., SBS in its strict sense and usual conception, favours characters that increase the persistence of their holders and act on all material and immaterial entities. Sorted entities could originate independently from each other, are not required to propagate and need not exhibit heredity. Natural selection is a specific form of SBS-sorting based on dynamic stability. It requires some form of heredity and is based on competition for the largest difference between the speed of generating its own copies and their expiration. SBS in its strict sense and selection thus have markedly different evolutionary consequences that are stressed in this paper. In contrast to selection, which is opportunistic, SBS is able to accumulate even momentarily detrimental characters that are advantageous for the long-term persistence of sorted entities. However, it lacks the amplification effect based on the preferential propagation of holders of advantageous characters. Thus, it works slower than selection and normally is unable to create complex adaptations. From a long-term perspective, SBS is a decisive force in evolution-especially macroevolution. SBS offers a new explanation for numerous evolutionary phenomena, including broad distribution and persistence of sexuality, altruistic behaviour, horizontal gene transfer, patterns of evolutionary stasis, planetary homeostasis, increasing ecosystem resistance to disturbances, and the universal decline of disparity in the evolution of metazoan lineages. SBS acts on all levels in all biotic and abiotic systems. It could be the only truly universal evolutionary process, and an explanatory framework based on SBS could provide new insight into the evolution of complex abiotic and biotic systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the Long-Term Stability and Temperature Coefficient of Dew-Point Hygrometers

NASA Astrophysics Data System (ADS)

Benyon, R.; Vicente, T.; Hernández, P.; De Rivas, L.; Conde, F.

2012-09-01

The continuous quest for improved specifications of optical dew-point hygrometers has raised customer expectations on the performance of these devices. In the absence of a long calibration history, users with a limited prior experience in the measurement of humidity, place reliance on manufacturer specifications to estimate long-term stability. While this might be reasonable in the case of measurement of electrical quantities, in humidity it can lead to optimistic estimations of uncertainty. This article reports a study of the long-term stability of some hygrometers and the analysis of their performance as monitored through regular calibration. The results of the investigations provide some typical, realistic uncertainties associated with the long-term stability of instruments used in calibration and testing laboratories. Together, these uncertainties can help in establishing initial contributions in uncertainty budgets, as well as in setting the minimum calibration requirements, based on the evaluation of dominant influence quantities.

Physical stability and resistance to peroxidation of a range of liquid-fill hard gelatin capsule products on extreme long-term storage.

PubMed

Bowtle, William; Kanyowa, Lionel; Mackenzie, Mark; Higgins, Paul

2011-06-01

The industrial take-up of liquid-fill hard capsule technology is limited in part by lack of published long-term physical and chemical stability data which demonstrate the robustness of the system. To assess the effects of extreme long-term storage on liquid-fill capsule product quality and integrity, with respect to both the capsules per se and a standard blister-pack type (foil-film blister). Fourteen sets of stored peroxidation-sensitive liquid-fill hard gelatin capsule product samples, originating ~20 years from the current study, were examined with respect to physical and selected chemical properties, together with microbiological evaluation. All sets retained physical integrity of capsules and blister-packs. Capsules were free of leaks, gelatin cross-linking, and microbiological growth. Eight samples met a limit (anisidine value, 20) commonly used as an index of peroxidation for lipid-based products with shelf lives of 2-3 years. Foil-film blister-packs using PVC or PVC-PVdC as the thermoforming film were well-suited packaging components for the liquid-fill capsule format. The study confirms the long-term physical robustness of the liquid-fill hard capsule format, together with its manufacturing and banding processes. It also indicates that various peroxidation-sensitive products using the capsule format may be maintained satisfactorily over very prolonged storage periods.

Stability of selected serum hormones and lipids after long-term storage in the Janus Serum Bank.

PubMed

Gislefoss, Randi E; Grimsrud, Tom K; Mørkrid, Lars

2015-04-01

The potential value of a biobank depends on the quality of the samples, i.e. how well they reflect the biological or biochemical state of the donors at the time of sampling. Documentation of sample quality has become a particularly important issue for researchers and users of biobank studies. The aim of this study was to investigate the long-term stability of selected components: cholesterol, high density cholesterol (HDLC), low density cholesterol (LDLC), apolipoprotein A1 (apo-A1), apolipoprotein B (apo B), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), thyroid stimulating hormone (TSH) and free thyroxin (FT4). Samples, stored at -25°C, from 520 men aged 40-49 years at blood sampling distributed in equally sized groups (n=130) according to length of storage, 0, 4, 17 and 29 years, respectively, were used in a cross sectional design. The freshly collected serum samples were used as a reference group to calculate storage related changes. The differences between fresh samples and samples stored for 29 years were substantial for apo-A1 (+12%), apo-B (+22.3%), HDLC (-69.2%), LDLC (+31.3%), and PRL (-33.5%), while total cholesterol, FSH, LH, TSH and FT4 did not show any significant difference. The study showed large differences in serum level of the selected components. The lipids and apolipoproteins were all changed except for total cholesterol. Most hormones investigated (FSH, LH, TSH and FT4) proved to be stable after 29 years of storage while PRL showed sign of degradation. The observed differences are probably due to long-term storage effects and/or external factors (i.e. diet and smoking). Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

An algorithm for the Italian atomic time scale

NASA Technical Reports Server (NTRS)

Cordara, F.; Vizio, G.; Tavella, P.; Pettiti, V.

1994-01-01

During the past twenty years, the time scale at the IEN has been realized by a commercial cesium clock, selected from an ensemble of five, whose rate has been continuously steered towards UTC to maintain a long term agreement within 3 x 10(exp -13). A time scale algorithm, suitable for a small clock ensemble and capable of improving the medium and long term stability of the IEN time scale, has been recently designed taking care of reducing the effects of the seasonal variations and the sudden frequency anomalies of the single cesium clocks. The new time scale, TA(IEN), is obtained as a weighted average of the clock ensemble computed once a day from the time comparisons between the local reference UTC(IEN) and the single clocks. It is foreseen to include in the computation also ten cesium clocks maintained in other Italian laboratories to further improve its reliability and its long term stability. To implement this algorithm, a personal computer program in Quick Basic has been prepared and it has been tested at the IEN time and frequency laboratory. Results obtained using this algorithm on the real clocks data relative to a period of about two years are presented.

Accurate prediction of vaccine stability under real storage conditions and during temperature excursions.

PubMed

Clénet, Didier

2018-04-01

Due to their thermosensitivity, most vaccines must be kept refrigerated from production to use. To successfully carry out global immunization programs, ensuring the stability of vaccines is crucial. In this context, two important issues are critical, namely: (i) predicting vaccine stability and (ii) preventing product damage due to excessive temperature excursions outside of the recommended storage conditions (cold chain break). We applied a combination of advanced kinetics and statistical analyses on vaccine forced degradation data to accurately describe the loss of antigenicity for a multivalent freeze-dried inactivated virus vaccine containing three variants. The screening of large amounts of kinetic models combined with a statistical model selection approach resulted in the identification of two-step kinetic models. Predictions based on kinetic analysis and experimental stability data were in agreement, with approximately five percentage points difference from real values for long-term stability storage conditions, after excursions of temperature and during experimental shipments of freeze-dried products. Results showed that modeling a few months of forced degradation can be used to predict various time and temperature profiles endured by vaccines, i.e. long-term stability, short time excursions outside the labeled storage conditions or shipments at ambient temperature, with high accuracy. Pharmaceutical applications of the presented kinetics-based approach are discussed. Copyright © 2018 The Author. Published by Elsevier B.V. All rights reserved.

Long-term stability of diurnal salivary cortisol and alpha-amylase secretion patterns.

PubMed

Skoluda, Nadine; La Marca, Roberto; Gollwitzer, Mario; Müller, Andreas; Limm, Heribert; Marten-Mittag, Birgitt; Gündel, Harald; Angerer, Peter; Nater, Urs M

2017-06-01

This study aimed to investigate long-term stability and variability of diurnal cortisol and alpha-amylase patterns. Diurnal cortisol and alpha-amylase secretion patterns were assessed on a single workday with three waves of measurement across a total time period of 24months in 189 participants. Separate hierarchical linear models were analyzed, with and without a number of potential predictor variables (age, BMI, smoking, chronic stress, stress reactivity). While low long-term stability was found in diurnal cortisol, the stability of diurnal alpha-amylase was moderate across the time period of 24months. Several predictor variables had a positive impact on diurnal cortisol and alpha-amylase secretion patterns averaged across waves. Our findings underpin the notion that long-term stability is not necessarily warranted in longitudinal studies. It is important to choose an appropriate study design when attempting to disentangle clinically and biologically relevant changes from naturally occurring variations in diurnal cortisol and alpha-amylase. Copyright © 2017 Elsevier Inc. All rights reserved.

Some Thoughts on Stability in Nonlinear Periodic Focusing Systems

DOE R&D Accomplishments Database

McMillan, E. M.

1967-09-05

A brief discussion is given of the long-term stability of particle motions through periodic focusing structures containing lumped nonlinear elements. A method is presented whereby one can specify the nonlinear elements in such a way as to generate a variety of structures in which the motion has long-term stability.

Long-term stability of sodium caseinate-stabilized nanoemulsions.

PubMed

Yerramilli, Manispuritha; Ghosh, Supratim

2017-01-01

Oil-in-water (5 wt%) nanoemulsions were prepared with different concentration (2.5-10 wt%) of sodium caseinate as a sole emulsifier and their long-term storage stability was investigated for 6 months. Previous studies associated with sodium caseinate looked only into nanoemulsion formation; hence the challenges with long-term stability were not addressed. All nanoemulsions displayed an average droplet size <200 nm, which remained unchanged over 6 months. However, all of them displayed rapid creaming due to unabsorbed protein induced depletion flocculation, whose extent increased with protein concentration, although the cream layer formed was weak and re-dispersible upon gentle mixing. Microstructural analysis of the cream layer showed compaction of flocculated nanodroplet network with time leaving the aqueous phase out. Calculation of depletion interaction energy showed an increase in inter-droplet attraction with protein concentration and decrease with a reduction in droplet size, making the nanoemulsions more resistant to flocculation than conventional emulsions. This work aids in understanding the dependence of protein concentration on long-term stability of sodium caseinate-stabilized nanoemulsions.

A novel high pressure, high temperature vessel used to conduct long-term stability measurements of silicon MEMS pressure transducers

NASA Astrophysics Data System (ADS)

Wisniewiski, David

2014-03-01

The need to quantify and to improve long-term stability of pressure transducers is a persistent requirement from the aerospace sector. Specifically, the incorporation of real-time pressure monitoring in aircraft landing gear, as exemplified in Tire Pressure Monitoring Systems (TPMS), has placed greater demand on the pressure transducer for improved performance and increased reliability which is manifested in low lifecycle cost and minimal maintenance downtime through fuel savings and increased life of the tire. Piezoresistive (PR) silicon MEMS pressure transducers are the primary choice as a transduction method for this measurement owing to their ability to be designed for the harsh environment seen in aircraft landing gear. However, these pressure transducers are only as valuable as the long-term stability they possess to ensure reliable, real-time monitoring over tens of years. The "heart" of the pressure transducer is the silicon MEMS element, and it is at this basic level where the long-term stability is established and needs to be quantified. A novel High Pressure, High Temperature (HPHT) vessel has been designed and constructed to facilitate this critical measurement of the silicon MEMS element directly through a process of mechanically "floating" the silicon MEMS element while being subjected to the extreme environments of pressure and temperature, simultaneously. Furthermore, the HPHT vessel is scalable to permit up to fifty specimens to be tested at one time to provide a statistically significant data population on which to draw reasonable conclusions on long-term stability. With the knowledge gained on the silicon MEMS element, higher level assembly to the pressure transducer envelope package can also be quantified as to the build-effects contribution to long-term stability in the same HPHT vessel due to its accommodating size. Accordingly, a HPHT vessel offering multiple levels of configurability and robustness in data measurement is presented, along with 10 year long-term stability results.

Long-term stability and properties of zirconia ceramics for heavy duty diesel engine components

NASA Technical Reports Server (NTRS)

Larsen, D. C.; Adams, J. W.

1985-01-01

Physical, mechanical, and thermal properties of commercially available transformation-toughened zirconia are measured. Behavior is related to the material microstructure and phase assemblage. The stability of the materials is assessed after long-term exposure appropriate for diesel engine application. Properties measured included flexure strength, elastic modulus, fracture toughness, creep, thermal shock, thermal expansion, internal friction, and thermal diffusivity. Stability is assessed by measuring the residual property after 1000 hr/1000C static exposure. Additionally static fatigue and thermal fatigue testing is performed. Both yttria-stabilized and magnesia-stabilized materials are compared and contrasted. The major limitations of these materials are short term loss of properties with increasing temperature as the metastable tetragonal phase becomes more stable. Fine grain yttria-stabilized material (TZP) is higher strength and has a more stable microstructure with respect to overaging phenomena. The long-term limitation of Y-TZP is excessive creep deformation. Magnesia-stabilized PSZ has relatively poor stability at elevated temperature. Overaging, decomposition, and/or destabilization effects are observed. The major limitation of Mg-PSZ is controlling unwanted phase changes at elevated temperature.

Related Studies in Long Term Lithium Battery Stability

NASA Technical Reports Server (NTRS)

Horning, R. J.; Chua, D. L.

1984-01-01

The continuing growth of the use of lithium electrochemical systems in a wide variety of both military and industrial applications is primarily a result of the significant benefits associated with the technology such as high energy density, wide temperature operation and long term stability. The stability or long term storage capability of a battery is a function of several factors, each important to the overall storage life and, therefore, each potentially a problem area if not addressed during the design, development and evaluation phases of the product cycle. Design (e.g., reserve vs active), inherent material thermal stability, material compatibility and self-discharge characteristics are examples of factors key to the storability of a power source.

Atomic-Scale Origin of Long-Term Stability and High Performance of p-GaN Nanowire Arrays for Photocatalytic Overall Pure Water Splitting.

PubMed

Kibria, Md Golam; Qiao, Ruimin; Yang, Wanli; Boukahil, Idris; Kong, Xianghua; Chowdhury, Faqrul Alam; Trudeau, Michel L; Ji, Wei; Guo, Hong; Himpsel, F J; Vayssieres, Lionel; Mi, Zetian

2016-10-01

The atomic-scale origin of the unusually high performance and long-term stability of wurtzite p-GaN oriented nanowire arrays is revealed. Nitrogen termination of both the polar (0001¯) top face and the nonpolar (101¯0) side faces of the nanowires is essential for long-term stability and high efficiency. Such a distinct atomic configuration ensures not only stability against (photo) oxidation in air and in water/electrolyte but, as importantly, also provides the necessary overall reverse crystal polarization needed for efficient hole extraction in p-GaN. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Space augmentation of military high-level waste disposal

NASA Technical Reports Server (NTRS)

English, T.; Lees, L.; Divita, E.

1979-01-01

Space disposal of selected components of military high-level waste (HLW) is considered. This disposal option offers the promise of eliminating the long-lived radionuclides in military HLW from the earth. A space mission which meets the dual requirements of long-term orbital stability and a maximum of one space shuttle launch per week over a period of 20-40 years, is a heliocentric orbit about halfway between the orbits of earth and Venus. Space disposal of high-level radioactive waste is characterized by long-term predictability and short-term uncertainties which must be reduced to acceptably low levels. For example, failure of either the Orbit Transfer Vehicle after leaving low earth orbit, or the storable propellant stage failure at perihelion would leave the nuclear waste package in an unplanned and potentially unstable orbit. Since potential earth reencounter and subsequent burn-up in the earth's atmosphere is unacceptable, a deep space rendezvous, docking, and retrieval capability must be developed.

Equilibrium high entropy alloy phase stability from experiments and thermodynamic modeling

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

Saal, James E.; Berglund, Ida S.; Sebastian, Jason T.

Long-term stability of high entropy alloys (HEAs) is a critical consideration for the design and practical application of HEAs. It has long been assumed that many HEAs are a kinetically-stabilized metastable structure, and recent experiments have confirmed this hypothesis by observing HEA ecomposition after long-termequilibration. In the presentwork,we demonstrate the use of the CALculation of PHAse Diagrams (CALPHAD) approach to predict HEA stability and processing parameters, comparing experimental long-term annealing observations to CALPHAD phase diagrams from a commercially-available HEA database. As a result, we find good agreement between single- and multi-phase predictions and experiments.

Equilibrium high entropy alloy phase stability from experiments and thermodynamic modeling

DOE PAGES

Saal, James E.; Berglund, Ida S.; Sebastian, Jason T.; ...

2017-10-29

Long-term stability of high entropy alloys (HEAs) is a critical consideration for the design and practical application of HEAs. It has long been assumed that many HEAs are a kinetically-stabilized metastable structure, and recent experiments have confirmed this hypothesis by observing HEA ecomposition after long-termequilibration. In the presentwork,we demonstrate the use of the CALculation of PHAse Diagrams (CALPHAD) approach to predict HEA stability and processing parameters, comparing experimental long-term annealing observations to CALPHAD phase diagrams from a commercially-available HEA database. As a result, we find good agreement between single- and multi-phase predictions and experiments.

Freeze drying optimization of polymeric nanoparticles for ocular flurbiprofen delivery: effect of protectant agents and critical process parameters on long-term stability.

PubMed

Ramos Yacasi, Gladys Rosario; Calpena Campmany, Ana Cristina; Egea Gras, María Antonia; Espina García, Marta; García López, María Luisa

2017-04-01

The stabilization of flurbiprofen loaded poly-ɛ-caprolactone nanoparticles (FB-PɛCL-NPs) for ocular delivery under accurate freeze-drying (FD) process provides the basis for a large-scale production and its commercial development. Optimization of the FD to improve long-term stability of ocular administration's FB-PɛCL-NPs. FB-PɛCL-NPs were prepared by solvent displacement method with poloxamer 188 (P188) as stabilizer. Freezing and primary drying (PD) were studied and optimized through freeze-thawing test and FD microscopy. Design of experiments was used to accurate secondary drying (SD) conditions and components concentration. Formulations were selected according to desired physicochemical properties. Furthermore, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to study interactions components. Optimized FB-PɛCL-NPs, stabilized with 3.5% (w/w) P188 and protected with 8% (w/w) poly(ethylene glycol), was submitted to precooling at +10 °C for 1 h, freezing at -50 °C for 4 h, PD at +5 °C and 0.140 mbar for 24 h and a SD at +45 °C during 10 h. These conditions showed 188.4 ± 1.3 nm, 0.087 ± 0.014, 85.5 ± 1.4%, 0.61 ± 0.12%, -16.4 ± 0.1 mV and 325 ± 7 mOsm/kg of average size, polydispersity index, entrapment efficiency, residual moisture, surface charge and osmolality, respectively. It performed a long-term stability >12 months. DSC and XRD spectra confirmed adequate chemical interaction between formulation components and showed a semi-crystalline state after FD. An optimal freeze dried ocular formulation was achieved. Evidently, the successful design of this promising colloidal system resulted from rational cooperation between a good formulation and the right conditions in the FD process.

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.

Development and validation of a stability-indicating high performance liquid chromatographic assay for benoxinate.

PubMed

Chorny, Michael; Levy, Daniel; Schumacher, Ilana; Lichaa, Chaim; Gruzman, Boris; Livshits, Oleg; Lomnicky, Yossi

2003-04-24

Benoxinate is a local anaesthetic used for ophthalmic applications. The aim of this study was to develop a rapid and simple stability-indicating method for the determination of benoxinate formulated for ophthalmic use, evaluate its long-term stability and identify its major degradation product. Benoxinate was eluted on a 10 microm Spherisorb phenyl column, 250 x 3.2 mm, with a mobile phase consisting of acetonitrile-buffer (pH 3.5) (35:65, v/v), pumped at 0.8 ml min(-1) flow rate. The buffer was composed of sodium dihydrogen phosphate (50 mM), sodium hydrogen sulfate (2.5 mM) and 1-heptanesulfonic acid sodium salt (5 mM). The analyte was quantified spectrophotometrically at 308 nm. The chromatograms of benoxinate formulations obtained by this method showed benoxinate (t = 4.5 min) well resolved from its degradation product (t = 2.3 min), which was separately identified by means of HPLC-MS as 4-amino-3-butoxybenzoic acid. The assay was demonstrated to have high accuracy, precision and linearity. The method was implemented in investigating the long-term stability of benoxinate 0.4% ophthalmic solutions. The method was found to be simple, quick and selective in determining benoxinate concentrations in fresh and aged preparations.

A Raman Lidar as Operational Tool for Long-Term Water Vapor, Temperature and Aerosol Profiling in the Swiss Meteorological Office

NASA Astrophysics Data System (ADS)

Simeonov, Dr; Dinoev, Dr; Serikov, Dr; Calpini, Dr; Bobrovnikov, Dr; Arshinov, Dr; Ristori, Dr; van den Bergh, Dr; Parlange, Dr

2010-09-01

To satisfy the rising demands on the quality and frequency of atmospheric water vapor, temperature and aerosol measurements used for numerical weather prediction models, climate change observations and special events (volcanoes, dust and smoke transport) monitoring, MeteoSwiss decided to implement a lidar at his main aerological station in Payerne. The instrument is narrow field of view, narrowband UV Raman lidar designed for continuous day and night operational profiling of tropospheric water vapor, aerosol and temperature The lidar was developed and built by the Swiss Federal Institute of Technology- Lausanne (EPFL) within a joint project with MeteoSwiss. To satisfy the requirements for operational exploitation in a meteorological network the lidar had to satisfy a number of criteria, the most important of which are: accuracy and precision, traceability of the measurement, long-term data consistency, long-term system stability, automated operation, requiring minimal maintenance by a technician, and eye safety. All this requirements were taken into account during the design phase of the lidar. After a ten months test phase of the lidar at Payerne it has been in regular operation since August 2008. Selected data illustrating interesting atmospheric phenomena captured by the lidar as well as long-term intercomparison with collocated microwave radiometer, GPS, radiosonding and an airborne DIAL will be presented and discussed. The talk will address also the technical availability, alignment and calibration stabilities of the instrument.

Long-Term Stability of Scores on the Wechsler Intelligence Scale for Children-Fourth Edition in Children with Learning Disabilities

ERIC Educational Resources Information Center

Lander, Jenny

2010-01-01

The present investigation explored the stability of scores on the Wechsler Intelligence Scale for Children-IV (WISC-IV) over approximately a three-year period. Previous research has suggested that some children with Learning Disabilities (LD) do not demonstrate long-term stability of intelligence. Legally, school districts are no longer required…

Cryoprotectant choice and analyses of freeze-drying drug suspension of nanoparticles with functional stabilisers.

PubMed

Wang, Lulu; Ma, Yingying; Gu, Yu; Liu, Yangyang; Zhao, Juan; Yan, Beibei; Wang, Yancai

2018-04-19

Freeze-drying is an effective way to improve long-term physical stability of nanosuspension in drug delivery applications. Nanosuspension also known as suspension of nanoparticles. In this study, the effect of freeze-drying with different cryoprotectants on the physicochemical characteristics of resveratrol (RSV) nanosuspension and quercetin (QUE) nanosuspension was evaluated. D-α-tocopheryl polyethylene glycol succinate (TPGS) and folate-modified distearoylphosphatidyl ethanolamine-polyethylene glycol (DSPE-PEG-FA) were selected as functional stabilisers formulated nanosuspension which were prepared by anti-solvent precipitation method. RSV nanoparticle size and QUE nanoparticle size were about 210 and 110 nm, respectively. The AFM and TEM results of nanosuspension showed uniform and irregular shape particles. After freeze-drying, the optimal concentration of four cryoprotectants was determined by the particle size of re-dispersed nanoparticles. The dissolution profile of drug nanoparticle significantly showed approximately at a 6-8-fold increase dissolution rate. Moreover, TPGS and DSPE-PEG-FA stabilised RSV nanosuspension and QUE nanosuspension samples showed better effect on long-term physical stability.

Grid scale drives the scale and long-term stability of place maps

PubMed Central

Mallory, Caitlin S; Hardcastle, Kiah; Bant, Jason S; Giocomo, Lisa M

2018-01-01

Medial entorhinal cortex (MEC) grid cells fire at regular spatial intervals and project to the hippocampus, where place cells are active in spatially restricted locations. One feature of the grid population is the increase in grid spatial scale along the dorsal-ventral MEC axis. However, the difficulty in perturbing grid scale without impacting the properties of other functionally-defined MEC cell types has obscured how grid scale influences hippocampal coding and spatial memory. Here, we use a targeted viral approach to knock out HCN1 channels selectively in MEC, causing grid scale to expand while leaving other MEC spatial and velocity signals intact. Grid scale expansion resulted in place scale expansion in fields located far from environmental boundaries, reduced long-term place field stability and impaired spatial learning. These observations, combined with simulations of a grid-to-place cell model and position decoding of place cells, illuminate how grid scale impacts place coding and spatial memory. PMID:29335607

75 FR 33769 - Manufacturing Extension Partnership (MEP) Availability of Funds for Projects To Develop and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-15

... to the long-term economic stability of the region. Please see the NIST MEP Web site, http://www.nist... region, and contribute to the long-term economic stability of the region. Competitive projects will use...

The coevolution of long-term pair bonds and cooperation.

PubMed

Song, Z; Feldman, M W

2013-05-01

The evolution of social traits may not only depend on but also change the social structure of the population. In particular, the evolution of pairwise cooperation, such as biparental care, depends on the pair-matching distribution of the population, and the latter often emerges as a collective outcome of individual pair-bonding traits, which are also under selection. Here, we develop an analytical model and individual-based simulations to study the coevolution of long-term pair bonds and cooperation in parental care, where partners play a Snowdrift game in each breeding season. We illustrate that long-term pair bonds may coevolve with cooperation when bonding cost is below a threshold. As long-term pair bonds lead to assortative interactions through pair-matching dynamics, they may promote the prevalence of cooperation. In addition to the pay-off matrix of a single game, the evolutionarily stable equilibrium also depends on bonding cost and accidental divorce rate, and it is determined by a form of balancing selection because the benefit from pair-bond maintenance diminishes as the frequency of cooperators increases. Our findings highlight the importance of ecological factors affecting social bonding cost and stability in understanding the coevolution of social behaviour and social structures, which may lead to the diversity of biological social systems. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Prioritization of Potential Mates' History of Sexual Fidelity During a Conjoint Ranking Task.

PubMed

Mogilski, Justin K; Wade, T Joel; Welling, Lisa L M

2014-07-01

This series of studies is the first to use conjoint analysis to examine how individuals make trade-offs during mate selection when provided information about a partner's history of sexual infidelity. Across three studies, participants ranked profiles of potential mates, with each profile varying across five attributes: financial stability, physical attractiveness, sexual fidelity, emotional investment, and similarity. They also rated each attribute separately for importance in an ideal mate. Overall, we found that for a long-term mate, participants prioritized a potential partner's history of sexual fidelity over other attributes when profiles were ranked conjointly. For a short-term mate, sexual fidelity, physical attractiveness, and financial stability were equally important, and each was more important than emotional investment and similarity. These patterns contrast with participants' self-reported importance ratings of each individual attribute. Our results are interpreted within the context of previous literature examining how making trade-offs affect mate selection. © 2014 by the Society for Personality and Social Psychology, Inc.

Short-Term Aging of NeFeB Magnets for Stirling Linear Alternator Applications

NASA Technical Reports Server (NTRS)

Niedra, Janis M.; Schwarze, Gene E. (Technical Monitor)

2001-01-01

NeFeB type magnets have been proposed for use in free piston Stirling engine driven, linear alternators to generate electric power during long duration space missions. These type of materials provide the highest energy product commercial magnets, thus minimizing alternator size or mass, but do not provide the high temperature stability of magnetic properties found in the SmCo type magnets. Therefore, to apply the NeFeB type magnets at elevated temperatures to multiyear space missions, their long-term aging characteristics must be determined. This report presents 200 hr aging data for six types of NeFeB magnets selected from three manufacturers. Aging was performed under vacuum at 150 C, with a steady demagnetizing field of 5 kOe applied. From the data produced by this short-term aging run, candidate magnet types were selected for a planned 12,000 hr long-term run. Depending on the manufacturer's magnet type, remanence losses observed ranged from 0 to 7%, when measured at 120 C on an established recoil line. Also, intrinsic coercivity losses up to about 4% were observed for the M-H curve at 120 C. In some cases, these coercivity losses were not recoverable by recharge of the magnet, indicating a structural change of the material.

Some Thoughts on Stability in Nonlinear Periodic Focusing Systems [Addendum

DOE R&D Accomplishments Database

McMillan, Edwin M.

1968-03-29

Addendum to September 5, 1967 report with the same title and with the abstract: A brief discussion is given of the long-term stability of particle motions through periodic focusing structures containing lumped nonlinear elements. A method is presented whereby one can specify the nonlinear elements in such a way as to generate a variety of structures in which the motion has long-term stability.

High-Temperature Tolerance in Multi-Scale Cermet Solar-Selective Absorbing Coatings Prepared by Laser Cladding.

PubMed

Pang, Xuming; Wei, Qian; Zhou, Jianxin; Ma, Huiyang

2018-06-19

In order to achieve cermet-based solar absorber coatings with long-term thermal stability at high temperatures, a novel single-layer, multi-scale TiC-Ni/Mo cermet coating was first prepared using laser cladding technology in atmosphere. The results show that the optical properties of the cermet coatings using laser cladding were much better than the preplaced coating. In addition, the thermal stability of the optical properties for the laser cladding coating were excellent after annealing at 650 °C for 200 h. The solar absorptance and thermal emittance of multi-scale cermet coating were 85% and 4.7% at 650 °C. The results show that multi-scale cermet materials are more suitable for solar-selective absorbing coating. In addition, laser cladding is a new technology that can be used for the preparation of spectrally-selective coatings.

Potentiometric sensors with carbon black supporting platinum nanoparticles.

PubMed

Paczosa-Bator, Beata; Cabaj, Leszek; Piech, Robert; Skupień, Krzysztof

2013-11-05

For the first time, a single-piece, all-solid-state ion-selective electrode was fabricated with carbon black supporting platinum nanoparticles (PtNPs-CB) and a polymeric membrane. The PtNPs-CB, as an intermediate layer, was drop-casted directly on the solid substrate, and then an ionophore-doped solvent polymeric membrane was added in order to form a sensor. The performance of the newly developed electrodes was evaluated on the basis of potassium and nitrate ions. The stability of the electrical potential for the electrodes was examined by performing current-reversal chronopotentiometry, and the influence of the interfacial water film was assessed by the potentiometric aqueous-layer test. Fabricated potassium- and nitrate-selective electrodes displayed a Nernstian slope and several outstanding properties such as high long-term potential stability, potential repeatability, and reproducibility.

From Cell to Module: Fabrication and Long-term Stability of Dye-sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Nursam, N. M.; Hidayat, J.; Muliani, L.; Anggraeni, P. N.; Retnaningsih, L.; Idayanti, N.

2017-07-01

Dye-sensitized solar cell (DSSC), which has been firstly developed by Graetzel et al back in 1991, has attracted a considerable interest since its discovery. However, two of the main challenges that the DSSC technology will have to overcome towards commercialization involve device scale-up and long-term stability. In our group, the fabrication technology of DSSC has been developed from laboratory to module scale over the past few years, nevertheless, the long-term stability has still became a major concern. In this contribution, the long-term DSSC performance in relation to their scale-up from cell to module is investigated. The photoelectrode of the DSSCs were fabricated using nanocrystalline titanium dioxide materials that were subsequently sensitized using ruthenium-based dye. Additionally, TiCl4 pre- and post-treatment were carried out to enhance the overall device efficiency. When fabricated as cells, the DSSC prototypes showed relatively stable performance during repeated tests over three months. In order to increase the output power of the solar cells, the DSSCs were then connected in a Z-type series connection to obtain sub-module panels. The DSSC sub-modules exhibit poor stability, particularly as indicated by the significant decrease in the short circuit current (ISC ). Herein, the effect of photoelectrode and sealant materials as well as module design are investigated, highlighting their profound influence upon the DSSC efficiency and long-term stability.

Materials Research for Advanced Inertial Instrumentation. Task 1. Dimensional Stability of Gyroscope Structural Materials.

DTIC Science & Technology

1981-12-01

instability are several among which some readily identifiable ones are phase trans- formation, relief of residual stresses, and microplastic deformation...selection procedures. ideally, advanced generations of inertial instruments require that induced long-term microplastic strains be maintained at levels...SECTION 2 OBJECTIVES The present objectives of this program are as follows: (1) To survey the literature on microplastic properties of materials and

Risk selection and risk adjustment: improving insurance in the individual and small group markets.

PubMed

Baicker, Katherine; Dow, William H

2009-01-01

Insurance market reforms face the key challenge of addressing the threat that risk selection poses to the availability, of stable, high-value insurance policies that provide long-term risk protection. Many of the strategies in use today fail to address this breakdown in risk pooling, and some even exacerbate it. Flexible risk adjustment schemes are a promising avenue for promoting market stability and limiting insurer cream-skimming, potentially providing greater benefits at lower cost. Reforms intended to increase insurance coverage and the value of care delivered will be much more effective if implemented in conjunction with policies that address these fundamental selection issues.

Role of sulfonation in the stability, reactivity, and selectivity of poly(ether imide) used to develop ion exchange membranes: DFT study with application to fuel cells.

PubMed

López-Chávez, Ernesto; Peña-Castañeda, Yésica A; de la Portilla-Maldonado, L César; Guzmán-Pantoja, Javier; Martínez-Magadán, José Manuel; Oviedo-Roa, Raúl; de Landa Castillo-Alvarado, Fray; Cruz-Torres, Armando

2014-07-01

The design of polymer electrolyte membranes for fuel cells must satisfy two equally important fundamental principles: optimization of the reactivity and the selectivity in order to improve the ion transport properties of the membrane as well as its long-term stability in the hydrated state at high temperature (above 100 °C). A study utilizing density functional theory (DFT) to elucidate the effect of the degree of sulfonation on the chemical stability, reactivity, and selectivity of poly(ether imide) (PEI), which allows the ionic transport properties of the membrane to be predicted, is reported here. Sulfonated poly(ether imide) (SPEI) structures with (-SO3H) n (n = 1-6) groups were built and optimized in order to calculate the above properties as functions of the number of sulfonyl groups. A comparative study demonstrated that the SPEI with four sulfonyl groups in its backbone is the polymer with the properties best suited for use in fuel cells.

Limitations and possibilities of green synthesis and long-term stability of colloidal Ag nanoparticles

NASA Astrophysics Data System (ADS)

Velgosová, Oksana; Mražíková, Anna

2017-12-01

In this paper the influence of algae life cycle and the solutions pH on the green synthesis of colloidal Ag nanoparticles (AgNPs) as well as effect of different storage conditions on AgNPs long-term stability was investigated. Silver nanoparticles were biologically synthesized using extracts of Parachlorella kessleri algae cultivated 1, 2, 3 and 4 weeks. The formation of AgNPs was monitored using a UV-vis spectrophotometer and verified by TEM observation. The results confirmed formation of polyhedron and/or near polyhedron AgNPs, ranging between 5 and 60 nm in diameter. The age of algae influenced the synthesis rate and an amount of AgNPs in solution. The best results were obtained using tree weeks old algae. UV-vis analysis and TEM observation also revealed that the size and the stability of AgNPs depend on the pH of solution. AgNPs formed in solutions of higher pH (8 and 10) are polyhedron, fine, with narrow size interval and stabile. Nanoparticles formed in solutions of low pH (2, 4 and 6) started to lose their stability on 10th day of experiment, and the particle size interval was wide. The long-term stability of AgNPs can be influenced by light and temperature conditions. The most significant stability loss was observed at day light and room temperature (21°C). After 200-days significant amount of agglomerated particles settled on the bottom of the Erlenmeyer flask. AgNPs stored at dark and room temperature showed better long-term stability, weak particles agglomeration was observed. AgNPs stored at dark and at temperature 5°C showed the best long-term stability. Such AgNPs remained spherical, fine (5-20 nm), with narrow size interval and stable (no agglomeration) even after more than six months.

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

DOE PAGES

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; ...

2016-02-25

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 in this paper, 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. In conclusion, 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

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

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.

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 in this paper, 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. In conclusion, the finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less

State of the art of aerobic granulation in continuous flow bioreactors.

PubMed

Kent, Timothy R; Bott, Charles B; Wang, Zhi-Wu

In the wake of the success of aerobic granulation in sequential batch reactors (SBRs) for treating wastewater, attention is beginning to turn to continuous flow applications. This is a necessary step given the advantages of continuous flow treatment processes and the fact that the majority of full-scale wastewater treatment plants across the world are operated with aeration tanks and clarifiers in a continuous flow mode. As in SBRs, applying a selection pressure, based on differences in either settling velocity or the size of the biomass, is essential for successful granulation in continuous flow reactors (CFRs). CFRs employed for aerobic granulation come in multiple configurations, each with their own means of achieving such a selection pressure. Other factors, such as bioaugmentation and hydraulic shear force, also contribute to aerobic granulation to some extent. Besides the formation of aerobic granules, long-term stability of aerobic granules is also a critical issue to be addressed. Inorganic precipitation, special inocula, and various operational optimization strategies have been used to improve granule long-term structural integrity. Accumulated studies reviewed in this work demonstrate that aerobic granulation in CFRs is capable of removing a wide spectrum of contaminants and achieving properties generally comparable to those in SBRs. Despite the notable research progress made toward successful aerobic granulation in lab-scale CFRs, to the best of our knowledge, there are only three full-scale tests of the technique, two being seeded with anammox-supported aerobic granules and the other with conventional aerobic granules; two other process alternatives are currently in development. Application of settling- or size-based selection pressures and feast/famine conditions are especially difficult to implement to these and similar mainstream systems. Future research efforts needs to be focused on the optimization of the granule-to-floc ratio, enhancement of granule activity, improvement of long-term granule stability, and a better understanding of aerobic granulation mechanisms in CFRs, especially in full-scale applications. Copyright © 2018 Elsevier Inc. All rights reserved.

The relationship of body size to survivorship of hatchling snapping turtles (Chelydra serpentina): an evaluation of the "bigger is better" hypothesis.

PubMed

Congdon, Justin D; Nagle, Roy D; Dunham, Arthur E; Beck, Chirstopher W; Kinney, Owen M; Yeomans, S Rebecca

1999-11-01

In many organisms, body size is positively correlated with traits that are presumably related to fitness. If directional selection frequently favors larger offspring (the "bigger is better" hypothesis), the results of such selection should be detectable with field experiments. We tested the "bigger is better" hypothesis in hatchling snapping turtles (Chelydra serpentina) by conducting one long-term and three short-term experiments on the University of Michigan E.S. George Reserve in southeastern Michigan. In the fall of 1995 and 1996, we released hatchlings at artificial nests separated from the nearest wetland by fences. We recorded the proportion of hatchlings recaptured, the time it took hatchlings to move to fences from artificial nests 45, 55, and 80 m away, and dispersion along the fence. We determined whether the response variables and probability of recapture at fences were associated with hatchling body size. During 1995, average travel times of hatchlings from the experimental nests were not related to distance from the fence; however, time to recapture was positively correlated with dispersion from the zero point on the fence, and the maximum time to reach the fence was almost twice as long for hatchlings from the 80-m nest compared to those from the 45-m nest. Sixty-seven percent of the hatchlings reached the fence and the proportions doing so from each nest were not different. Body size was not significantly related to probability of recapture in either of the 1995 experiments. In 1996, 59% of released hatchlings were recaptured. Time to recapture was not related to dispersion from the zero point or to body size. Cubic spline analysis suggested stabilizing selection on body size. We also conducted a set of long-term hatchling release experiments between 1980-1993 to compare the survival of hatchlings released at nest sites to that of hatchlings released directly into marshes, and we looked for relationships between survivorship and hatchling body size. During 7 years in which more than 30 hatchlings were released, 413 hatchlings were released directly into the marsh and 262 were released at nests: their probability of survival did not differ. Over all years, for both release groups combined and for each group separately, survival was not related to body size. In 1983 alone, survival was also not related to body size for either group or for both groups combined. In our three short-term experiments and one long-term experiment, we found no evidence to support the "bigger is better" hypothesis. When selection on body size did occur, selection was stabilizing, not directional for larger size.

In Vivo Integrity and Biological Fate of Chelator-Free Zirconium-89-Labeled Mesoporous Silica Nanoparticles

PubMed Central

2015-01-01

Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 (89Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (−Si–O–) from two types of silica nanoparticles investigated. This work reports 89Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, 89Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future. PMID:26213260

In Vivo Integrity and Biological Fate of Chelator-Free Zirconium-89-Labeled Mesoporous Silica Nanoparticles.

PubMed

Chen, Feng; Goel, Shreya; Valdovinos, Hector F; Luo, Haiming; Hernandez, Reinier; Barnhart, Todd E; Cai, Weibo

2015-08-25

Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 ((89)Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (-Si-O(-)) from two types of silica nanoparticles investigated. This work reports (89)Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, (89)Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future.

Assessment of the short-term radiometric stability between Terra MODIS and Landsat 7 ETM+ sensors

USGS Publications Warehouse

Choi, Taeyoung; Xiong, Xiaoxiong; Chander, Gyanesh; Angal, A.

2009-01-01

Short-term radiometric stability was evaluated using continuous ETM+ scenes within a single orbit (contact period) and the corresponding MODIS scenes for the four matching solar reflective visible and near-infrared (VNIR) band pairs between the two sensors. The near-simultaneous earth observations were limited by the smaller swath size of ETM+ (183 km) compared to MODIS (2330 km). Two sets of continuous granules for Terra MODIS and Landsat 7 ETM+ were selected and mosaicked based on pixel geolocation information for noncloudy pixels over the African continent. The matching pixel pairs were resampled from a fine to a coarse pixel resolution, and the at-sensor spectral radiance values for a wide dynamic range of the sensors were compared and analyzed, covering various surface types. The following study focuses on radiometric stability analysis from the VNIR band-pairs of ETM+ and MODIS. The Libya-4 desert target was included in the path of this continuous orbit, which served as a verification point between the short-term and the long-term trending results from previous studies. MODTRAN at-sensor spectral radiance simulation is included for a representative desert surface type to evaluate the consistency of the results.

Elders with implant overdentures: a 22-year clinical report.

PubMed

Alsabeeha, Nabeel H M

2012-09-01

To report on the long-term survival and prosthodontic maintenance of two edentulous adults with mandibular overdentures supported by hydroxyapatite (HA)-coated implants. Mandibular implant overdentures are a successful treatment option with positive impact on the quality of life of elderly edentulous adults. Long-term survival of the implants requires continued rigorous prosthodontic maintenance. Two elderly edentulous adults with mandibular overdentures supported by 2 HA-coated implants were presented for prosthodontic rehabilitation after 22 years of placement. The implants were osseo-integrated and surviving at presentation based on accepted criteria. The mandibular implant overdentures suffered recurrent loss of retention and stability. Prosthodontic treatment involving the replacement of defective attachment systems and construction of new sets of mandibular implant overdentures opposing complete maxillary dentures is presented. The long-term survival of mandibular 2-implant overdentures requires continued prosthodontic maintenance. A conservative approach in the rehabilitation of two older edentulous adults with mandibular 2-implant overdentures was described including proper selection of attachment systems. © 2012 The Gerodontology Society and John Wiley & Sons A/S.

Stability of Chronic Hepatitis-Related Parameters in Serum Samples After Long-Term Storage.

PubMed

Yu, Rentao; Dan, Yunjie; Xiang, Xiaomei; Zhou, Yi; Kuang, Xuemei; Yang, Ge; Tang, Yulan; Liu, Mingdong; Kong, Weilong; Tan, Wenting; Deng, Guohong

2017-06-01

Serum samples are widely used in clinical research, but a comprehensive research of the stability of parameters relevant to chronic hepatitis and the effect of a relatively long-term (up to 10 years) storage on the stability have rarely been studied. To investigate the stability of chronic hepatitis-related parameters in serum samples after long-term storage. The storage stability of common clinical parameters such as total bile acid (TBA), total bilirubin (TBIL), potassium, cholesterol, and protein parameters such as alanine aminotransferase (ALT), creatine kinase (CK), γ-glutamyltransferase (GGT), albumin, high-density lipoprotein (HDL) and also hepatitis B virus (HBV) DNA, hepatitis C virus (HCV) RNA, hepatitis B surface antigen (HBsAg), and chemokine (C-X-C motif) ligand 10 (CXCL10) were tested in serum samples after storing at -20°C or -70°C for 1, 2, 3, 7, 8, and 10 years. Levels of TBA, TBIL, and protein parameters such as ALT, CK, GGT, HDL, and HBsAg decreased significantly, but levels of potassium and cholesterol increased significantly after long-term storage, whereas blood glucose and triglycerides were stable during storage. HBV DNA remained stable at -70°C but changed at -20°C, whereas HCV RNA was stable after 1-, 2-, and 3-year storage. CXCL10 was still detectable after 8-year storage. Low temperatures (-70°C/80°C) are necessary for storage of serum samples in chronic hepatitis B research after long-term storage.

A study to assess the long-term stability of the ionization chamber reference system in the LNMRI

NASA Astrophysics Data System (ADS)

Trindade Filho, O. L.; Conceição, D. A.; da Silva, C. J.; Delgado, J. U.; de Oliveira, A. E.; Iwahara, A.; Tauhata, L.

2018-03-01

Ionization chambers are used as secondary standard in order to maintain the calibration factors of radionuclides in the activity measurements in metrology laboratories. Used as radionuclide calibrator in nuclear medicine clinics to control dose in patients, its long-term performance is not evaluated systematically. A methodology for long-term evaluation for its stability is monitored and checked. Historical data produced monthly of 2012 until 2017, by an ionization chamber, electrometer and 226Ra, were analyzed via control chart, aiming to follow the long-term performance. Monitoring systematic errors were consistent within the limits of control, demonstrating the quality of measurements in compliance with ISO17025.

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.

The Effect of a Short-Term and Long-Term Whole-Body Vibration in Healthy Men upon the Postural Stability

PubMed Central

Piecha, Magdalena; Juras, Grzegorz; Król, Piotr; Sobota, Grzegorz; Polak, Anna; Bacik, Bogdan

2014-01-01

The study aimed to establish the short-term and long-term effects of whole-body vibration on postural stability. The sample consisted of 28 male subjects randomly allocated to four comparative groups, three of which exercised on a vibration platform with parameters set individually for the groups. The stabilographic signal was recorded before the test commenced, after a single session of whole-body vibration, immediately after the last set of exercises of the 4-week whole-body vibration training, and one week after the training ended. The subjects were exposed to vibrations 3 times a week for 4 weeks. Long-term vibration training significantly shortened the rambling and trembling paths in the frontal plane. The path lengths were significantly reduced in the frontal plane one week after the training end date. Most changes in the values of the center of pressure (COP) path lengths in the sagittal and frontal plane were statistically insignificant. We concluded that long-term vibration training improves the postural stability of young healthy individuals in the frontal plane. PMID:24520362

The performance and long-term stability of low-cost separators in single-chamber bottle-type microbial fuel cells.

PubMed

Kondaveeti, Sanath; Kakarla, Ramesh; Kim, Hong Suck; Kim, Byung-Goon; Min, Booki

2018-02-01

This study evaluates long-term stability of low-cost separators in single-chamber bottle-type microbial fuel cells with domestic wastewater. Low-cost separators tested in this study were nonwoven fabrics (NWF) of polypropylene (PP80, PP100), textile fabrics of polyphenylene sulfide (PPS), sulfonated polyphenylene sulfide (SPPS), and cellulose esters. NWF PP80 separator generated the highest power density of 280 mW/m 2 , which was higher than with ion-exchange membranes (cation exchange membrane; CEM = 271 mW/m 2 , cation exchange membrane; CMI = 196 mW/m 2 , Nafion = 260 mW/m 2 ). MFC operations with other size-selective separators such as SPPS, PPS, and cellulose esters exhibited power densities of 261, 231, and 250 mW/m 2 , respectively. During a 280-day operation, initial power density of PP80 (278 mW/m 2 ) was decreased to 257 mW/m 2 , but this decrease was smaller than with others (Nafion: 265-230 mW/m 2 ; PP100: 220-126 mW/m 2 ). The anode potential of around -430 mV did not change much with all separators in the long-term operation, but the initial cathode potential gradually decreased. Fouling analysis suggested that the presence of carbonaceous substance on Nafion and PP80 after 280 days of operation and Nafion was subject to be more biofouling.

Multicore-shell nanofiber architecture of polyimide/polyvinylidene fluoride blend for thermal and long-term stability of lithium ion battery separator.

PubMed

Park, Sejoon; Son, Chung Woo; Lee, Sungho; Kim, Dong Young; Park, Cheolmin; Eom, Kwang Sup; Fuller, Thomas F; Joh, Han-Ik; Jo, Seong Mu

2016-11-11

Li-ion battery, separator, multicoreshell structure, thermal stability, long-term stability. A nanofibrous membrane with multiple cores of polyimide (PI) in the shell of polyvinylidene fluoride (PVdF) was prepared using a facile one-pot electrospinning technique with a single nozzle. Unique multicore-shell (MCS) structure of the electrospun composite fibers was obtained, which resulted from electrospinning a phase-separated polymer composite solution. Multiple PI core fibrils with high molecular orientation were well-embedded across the cross-section and contributed remarkable thermal stabilities to the MCS membrane. Thus, no outbreaks were found in its dimension and ionic resistance up to 200 and 250 °C, respectively. Moreover, the MCS membrane (at ~200 °C), as a lithium ion battery (LIB) separator, showed superior thermal and electrochemical stabilities compared with a widely used commercial separator (~120 °C). The average capacity decay rate of LIB for 500 cycles was calculated to be approximately 0.030 mAh/g/cycle. This value demonstrated exceptional long-term stability compared with commercial LIBs and with two other types (single core-shell and co-electrospun separators incorporating with functionalized TiO 2 ) of PI/PVdF composite separators. The proper architecture and synergy effects of multiple PI nanofibrils as a thermally stable polymer in the PVdF shell as electrolyte compatible polymers are responsible for the superior thermal performance and long-term stability of the LIB.

Multicore-shell nanofiber architecture of polyimide/polyvinylidene fluoride blend for thermal and long-term stability of lithium ion battery separator

PubMed Central

Park, Sejoon; Son, Chung Woo; Lee, Sungho; Kim, Dong Young; Park, Cheolmin; Eom, Kwang Sup; Fuller, Thomas F.; Joh, Han-Ik; Jo, Seong Mu

2016-01-01

Li-ion battery, separator, multicoreshell structure, thermal stability, long-term stability. A nanofibrous membrane with multiple cores of polyimide (PI) in the shell of polyvinylidene fluoride (PVdF) was prepared using a facile one-pot electrospinning technique with a single nozzle. Unique multicore-shell (MCS) structure of the electrospun composite fibers was obtained, which resulted from electrospinning a phase-separated polymer composite solution. Multiple PI core fibrils with high molecular orientation were well-embedded across the cross-section and contributed remarkable thermal stabilities to the MCS membrane. Thus, no outbreaks were found in its dimension and ionic resistance up to 200 and 250 °C, respectively. Moreover, the MCS membrane (at ~200 °C), as a lithium ion battery (LIB) separator, showed superior thermal and electrochemical stabilities compared with a widely used commercial separator (~120 °C). The average capacity decay rate of LIB for 500 cycles was calculated to be approximately 0.030 mAh/g/cycle. This value demonstrated exceptional long-term stability compared with commercial LIBs and with two other types (single core-shell and co-electrospun separators incorporating with functionalized TiO2) of PI/PVdF composite separators. The proper architecture and synergy effects of multiple PI nanofibrils as a thermally stable polymer in the PVdF shell as electrolyte compatible polymers are responsible for the superior thermal performance and long-term stability of the LIB. PMID:27833132

Long Term Stability of Learning Outcomes in Undergraduates after an Open-Inquiry Instruction on Thermal Science

ERIC Educational Resources Information Center

Adorno, Dominique Persano; Pizzolato, Nicola; Fazio, Claudio

2018-01-01

This paper investigates the efficacy of an open-inquiry approach to achieve a long term stability of physics instruction. This study represents the natural continuation of a research project started four years ago when a sample of thirty engineering undergraduates, having already attended traditional university physics instruction, were involved…

Development of side-chain NLO polymer materials with high electro-optic activity and long-term stability

NASA Astrophysics Data System (ADS)

Huang, Diyun; Parker, Timothy; Guan, Hann Wen; Cong, Shuxin; Jin, Danliang; Dinu, Raluca; Chen, Baoquan; Tolstedt, Don; Wolf, Nick; Condon, Stephen

2005-01-01

The electro-optic coefficient and long-term dipole alignment stability are two major factors in the development of high performance NLO materials for the application of high-speed EO devices. We have developed a high performance non-linear organic chromophore and incorporated it into a crosslinkable side-chain polyimide system. The polymer was synthesized through stepwise grafting of the crosslinker followed by the chromophore onto the polyimide backbone via esterification. Different chromophore loading levels were achieved by adjusting the crosslinker/chromophore feeding ratio. The polyimides films were contact-poled with second-harmonic generation monitoring. A large EO coefficient value was obtained and good long-term thermal stability at 85°C was observed.

Hampered long-term depression and thin spine loss in the nucleus accumbens of ethanol-dependent rats.

PubMed

Spiga, Saturnino; Talani, Giuseppe; Mulas, Giovanna; Licheri, Valentina; Fois, Giulia R; Muggironi, Giulia; Masala, Nicola; Cannizzaro, Carla; Biggio, Giovanni; Sanna, Enrico; Diana, Marco

2014-09-02

Alcoholism involves long-term cognitive deficits, including memory impairment, resulting in substantial cost to society. Neuronal refinement and stabilization are hypothesized to confer resilience to poor decision making and addictive-like behaviors, such as excessive ethanol drinking and dependence. Accordingly, structural abnormalities are likely to contribute to synaptic dysfunctions that occur from suddenly ceasing the use of alcohol after chronic ingestion. Here we show that ethanol-dependent rats display a loss of dendritic spines in medium spiny neurons of the nucleus accumbens (Nacc) shell, accompanied by a reduction of tyrosine hydroxylase immunostaining and postsynaptic density 95-positive elements. Further analysis indicates that "long thin" but not "mushroom" spines are selectively affected. In addition, patch-clamp experiments from Nacc slices reveal that long-term depression (LTD) formation is hampered, with parallel changes in field potential recordings and reductions in NMDA-mediated synaptic currents. These changes are restricted to the withdrawal phase of ethanol dependence, suggesting their relevance in the genesis of signs and/or symptoms affecting ethanol withdrawal and thus the whole addictive cycle. Overall, these results highlight the key role of dynamic alterations in dendritic spines and their presynaptic afferents in the evolution of alcohol dependence. Furthermore, they suggest that the selective loss of long thin spines together with a reduced NMDA receptor function may affect learning. Disruption of this LTD could contribute to the rigid emotional and motivational state observed in alcohol dependence.

Therapy-induced selective loss of leukemia-initiating activity in murine adult T cell leukemia

PubMed Central

El Hajj, Hiba; El-Sabban, Marwan; Hasegawa, Hideki; Zaatari, Ghazi; Ablain, Julien; Saab, Shahrazad T.; Janin, Anne; Mahfouz, Rami; Nasr, Rihab; Kfoury, Youmna; Nicot, Christophe; Hermine, Olivier; Hall, William

2010-01-01

Chronic HTLV-I (human T cell lymphotropic virus type I) infection may cause adult T cell leukemia/lymphoma (ATL), a disease with dismal long-term prognosis. The HTLV-I transactivator, Tax, initiates ATL in transgenic mice. In this study, we demonstrate that an As2O3 and IFN-α combination, known to trigger Tax proteolysis, cures Tax-driven ATL in mice. Unexpectedly, this combination therapy abrogated initial leukemia engraftment into secondary recipients, whereas the primary tumor bulk still grew in the primary hosts, only to ultimately abate later on. This loss of initial transplantability required proteasome function. A similar regimen recently yielded unprecedented disease control in human ATL. Our demonstration that this drug combination targeting Tax stability abrogates tumor cell immortality but not short-term growth may foretell a favorable long-term efficiency of this regimen in patients. PMID:21135137

Long-term stability of FeSO4 and H2SO4 treated chromite ore processing residue (COPR): Importance of H+ and SO42.

PubMed

Wang, Xin; Zhang, Jingdong; Wang, Linling; Chen, Jing; Hou, Huijie; Yang, Jiakuan; Lu, Xiaohua

2017-01-05

In this study, the long-term stability of Cr(VI) in the FeSO 4 and H 2 SO 4 (FeSO 4 -H 2 SO 4 ) treated chromite ore processing residue (COPR) after 400 curing days and the stabilization mechanisms were investigated. FeSO 4 -H 2 SO 4 treatment significantly reduced toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) Cr(VI) concentrations to lower than the regulatory limit of 1.5mgL -1 (HJ/T 301-2007, China EPA) even for the samples curing 400days, achieving an outstanding long-term stability. Our independent leaching tests revealed that H + and SO 4 2- have synergistic effect on promoting the release of Cr(VI), which would make Cr(VI) easier accessed by Fe(II) during stabilization. The contributions of H + and SO 4 2- to Cr(VI) release ratio were 25%-44% and 19%-38%, respectively, as 5mol H 2 SO 4 per kg COPR was used. X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and alkaline digestion analyses were also employed to interpret the possible stabilization mechanism. Cr(VI) released from COPR solid was reduced to Cr(III) by Fe(II), and then formed stable Fe x Cr (1-x) (OH) 3 precipitate. This study provides a facile and reliable scheme for COPR stabilization, and verifies the excellent long-term stability of the FeSO 4 -H 2 SO 4 treated COPR. Copyright © 2016 Elsevier B.V. All rights reserved.

[Epidemiologic findings on the spontaneous long-term course of psychogenic disease over 10 years].

PubMed

Franz, M; Schepank, H; Reister, G; Schellberg, D

1994-01-01

207 individuals were selected from a random sample of the adult urban population of Mannheim according to the criterion of medium psychogenic impairment (high-risk population) and investigated three times between 1979 and 1991 with regard to prevalence and severity of psychogenic disorders. In contrast to clinical investigations, the present data render statements on the spontaneous course of psychogenic disorders in the general population. The existing psychogenic impairment was determined by means of various operationalizations (symptomatology, ICD-diagnoses, severity of impairment). The available data indicate a high stability of psychogenic impairment in the spontaneous course. Group statistically the severity of impairment even increases in the long term course. However, different subtypes of course in the investigated high-risk population can be identified by a cluster analysis.

[Rehabilitation in rheumatology].

PubMed

Luttosch, F; Baerwald, C

2010-10-01

Rehabilitation in rheumatology focuses on prevention of functional disorders of the musculoskeletal system, maintenance of working ability and prevention of care dependency. Drug treatment alone rarely results in long-term remission, therefore rehabilitative measures must be integrated into rheumatic care. Rehabilitative therapy in rheumatology includes physiotherapy, patient education and occupational therapy. Positive effects of physical therapy methods have been proven by various studies. Patient education and occupational therapy are important tools for stabilizing the course of the disease. To maintain positive rehabilitative results patients have to be involved in the selection of treatment measures and should take an active part in the long-term treatment process. Despite proven efficacy of physical measures there is evidence for a lack of utilization of rehabilitative therapy due to increasing cost pressure in the health care system which will further increase over time.

Stability and Response of Polygenic Traits to Stabilizing Selection and Mutation

PubMed Central

de Vladar, Harold P.; Barton, Nick

2014-01-01

When polygenic traits are under stabilizing selection, many different combinations of alleles allow close adaptation to the optimum. If alleles have equal effects, all combinations that result in the same deviation from the optimum are equivalent. Furthermore, the genetic variance that is maintained by mutation–selection balance is 2μ/S per locus, where μ is the mutation rate and S the strength of stabilizing selection. In reality, alleles vary in their effects, making the fitness landscape asymmetric and complicating analysis of the equilibria. We show that that the resulting genetic variance depends on the fraction of alleles near fixation, which contribute by 2μ/S, and on the total mutational effects of alleles that are at intermediate frequency. The interplay between stabilizing selection and mutation leads to a sharp transition: alleles with effects smaller than a threshold value of 2μ/S remain polymorphic, whereas those with larger effects are fixed. The genetic load in equilibrium is less than for traits of equal effects, and the fitness equilibria are more similar. We find that if the optimum is displaced, alleles with effects close to the threshold value sweep first, and their rate of increase is bounded by μS. Long-term response leads in general to well-adapted traits, unlike the case of equal effects that often end up at a suboptimal fitness peak. However, the particular peaks to which the populations converge are extremely sensitive to the initial states and to the speed of the shift of the optimum trait value. PMID:24709633

Precise and long-term stabilization of the carrier-envelope phase of femtosecond laser pulses using an enhanced direct locking technique.

PubMed

Yu, Tae Jun; Hong, Kyung-Han; Choi, Hyun-Gyug; Sung, Jae Hee; Choi, Il Woo; Ko, Do-Kyeong; Lee, Jongmin; Kim, Junwon; Kim, Dong Eon; Nam, Chang Hee

2007-06-25

We demonstrate a long-term operation with reduced phase noise in the carrier-envelope-phase (CEP) stabilization process by employing a double feedback loop and an improved signal detection in the direct locking technique [Opt. Express 13, 2969 (2005)]. A homodyne balanced detection method is employed for efficiently suppressing the dc noise in the f-2f beat signal, which is converted into the CEP noise in the direct locking loop working at around zero carrier-envelope offset frequency (f(ceo)). In order to enhance the long-term stability, we have used the double feedback scheme that modulates both the oscillator pump power for a fast control and the intracavity-prism insertion depth for a slow and high-dynamic-range control. As a result, the in-loop phase jitter is reduced from 50 mrad of the previous result to 29 mrad, corresponding to 13 as in time scale, and the long-term stable operation is achieved for more than 12 hours.

Paper Microzone Plates as Analytical Tools for Studying Enzyme Stability: A Case Study on the Stabilization of Horseradish Peroxidase Using Trehalose and SU-8 Epoxy Novolac Resin.

PubMed

Ganaja, Kirsten A; Chaplan, Cory A; Zhang, Jingyi; Martinez, Nathaniel W; Martinez, Andres W

2017-05-16

Paper microzone plates in combination with a noncontact liquid handling robot were demonstrated as tools for studying the stability of enzymes stored on paper. The effect of trehalose and SU-8 epoxy novolac resin (SU-8) on the stability of horseradish peroxidase (HRP) was studied in both a short-term experiment, where the activity of various concentrations of HRP dried on paper were measured after 1 h, and a long-term experiment, where the activity of a single concentration of HRP dried and stored on paper was monitored for 61 days. SU-8 was found to stabilize HRP up to 35 times more than trehalose in the short-term experiment for comparable concentrations of the two reagents, and a 1% SU-8 solution was found to stabilize HRP approximately 2 times more than a 34% trehalose solution in both short- and long-term experiments. The results suggest that SU-8 is a promising candidate for use as an enzyme-stabilizing reagent for paper-based diagnostic devices and that the short-term experiment could be used to quickly evaluate the capacity of various reagents for stabilizing enzymes to identify and characterize new enzyme-stabilizing reagents.

A review on chemiresistive room temperature gas sensors based on metal oxide nanostructures, graphene and 2D transition metal dichalcogenides.

PubMed

Joshi, Nirav; Hayasaka, Takeshi; Liu, Yumeng; Liu, Huiliang; Oliveira, Osvaldo N; Lin, Liwei

2018-03-10

Room-temperature (RT) gas sensing is desirable for battery-powered or self-powered instrumentation that can monitor emissions associated with pollution and industrial processes. This review (with 171 references) discusses recent advances in three types of porous nanostructures that have shown remarkable potential for RT gas sensing. The first group comprises hierarchical oxide nanostructures (mainly oxides of Sn, Ni, Zn, W, In, La, Fe, Co). The second group comprises graphene and its derivatives (graphene, graphene oxides, reduced graphene oxides, and their composites with metal oxides and noble metals). The third group comprises 2D transition metal dichalcogenides (mainly sulfides of Mo, W, Sn, Ni, also in combination with metal oxides). They all have been found to enable RT sensing of gases such as NOx, NH 3 , H 2 , SO 2 , CO, and of vapors such as of acetone, formaldehyde or methanol. Attractive features also include high selectivity and sensitivity, long-term stability and affordable costs. Strengths and limitations of these materials are highlighted, and prospects with respect to the development of new materials to overcome existing limitations are discussed. Graphical Abstract The review summarizes the most significant progresses related to room temperature gas sensing by using hierarchical oxide nanostructures, graphene and its derivatives and 2D transition metal dichalcogenides, highlighting the peculiar gas sensing behavior with enhanced selectivity, sensitivity and long-term stability.

Effect of Encapsulation on Antimicrobial Activity of
Herbal Extracts with Lysozyme

PubMed Central

Matouskova, Petra; Bokrova, Jitka; Benesova, Pavla

2016-01-01

Summary Resistance of microorganisms to antibiotics has increased. The use of natural components with antimicrobial properties can be of great significance to reduce this problem. The presented work is focused on the study of the effect of encapsulation of selected plant and animal antimicrobial substances (herbs, spices, lysozyme and nisin) on their activity and stability. Antimicrobial components were packaged into liposomes and polysaccharide particles (alginate, chitosan and starch). Antimicrobial activity was tested against two Gram-positive (Bacillus subtilis and Micrococcus luteus) and two Gram-negative (Escherichia coli and Serratia marcescens) bacteria. Encapsulation was successful in all types of polysaccharide particles and liposomes. The prepared particles exhibited very good long-term stability, especially in aqueous conditions. Antimicrobial activity was retained in all types of particles. Liposomes with encapsulated herb and spice extracts exhibited very good inhibitory effect against all tested bacterial strains. Most of herbal extracts had very good antimicrobial effect against the tested Gram-negative bacterial strains, while Gram-positive bacteria were more sensitive to lysozyme particles. Thus, particles with co-encapsulated herbs and lysozyme are more active against different types of bacteria, and more stable and more effective during long-term storage. Particles with encapsulated mixture of selected plant extracts and lysozyme could be used as complex antimicrobial preparation with controlled release in the production of food and food supplements, pharmaceutical and cosmetic industries. PMID:27956862

Frequency stability of maser oscillators operated with cavity Q. [hydrogen and rubidium masers

NASA Technical Reports Server (NTRS)

Tetu, M.; Tremblay, P.; Lesage, P.; Petit, P.; Audoin, C.

1982-01-01

The short term frequency stability of masers equipped with an external feedback loop to increase the cavity quality factor was studied. The frequency stability of a hydrogen and a rubidium maser were measured and compared with theoretical evaluation. It is shown that the frequency stability passes through an optimum when the cavity Q is varied. Long term fluctuations are discussed and the optimum mid term frequency stability achievably by small size active and passive H-masers is considered.

Long-term effect of lime-fly ash treated soils.

DOT National Transportation Integrated Search

2003-12-01

In October of 2000 MDOT initiated State Study No. 147, entitled "Long-Term Effect of Lime-Fly Ash Treated Soils." The purpose of this study : was to evaluate the long-term performance of LFA stabilized soil as a base course material. Part of the impe...

Clinical characteristics and long-term response to mood stabilizers in patients with bipolar disorder and different age at onset

PubMed Central

Dell’Osso, Bernardo; Buoli, Massimiliano; Riundi, Riccardo; D’Urso, Nazario; Pozzoli, Sara; Bassetti, Roberta; Mundo, Emanuela; Altamura, A Carlo

2009-01-01

Introduction Bipolar disorder (BD) is a prevalent, comorbid, and impairing condition. Potential predictors of response to pharmacological treatment are object of continuous investigation in patients with BD. The present naturalistic study was aimed to assess clinical features and long-term response to mood stabilizers in a sample of bipolar subjects with different ages at onset. Methods The study sample included 108 euthymic patients, diagnosed as affected by BD, either type I or II, according to the DSM-IV-TR, who were started on mood stabilizer treatment. Patients were followed-up for 24 months and the occurrence of any mood episode collected. At the end of the follow-up, patients were divided in 3 subgroups according to the age at onset (early-onset ≤30 years, middle-onset >30–≤45 years, and late-onset >45 years, respectively) and the long-term response to mood stabilizers was compared between them along with other clinical features. Results The three subgroups showed significant differences in terms of clinical and demographic features and, with respect to long-term response to mood stabilizers, the early-onset subgroup showed a better outcome in terms of reduction of major depressive episodes during the 24-month follow-up compared to the other subgroups (one way ANOVA, F = 3.57, p = 0.032). Conclusions Even though further controlled studies are needed to clarify the relationship between age at onset and outcome in BD, the present follow-up study suggests clinical peculiarities and different patterns of response to mood stabilizers across distinct subgroups of patients with BD and different ages at onset. PMID:19649214

LONG TERM STABILITY STUDY AT FNAL AND SLAC USING BINP DEVELOPED HYDROSTATIC LEVEL SYSTEM

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

Seryi, Andrei

2003-05-28

Long term ground stability is essential for achieving the performance goals of the Next Linear Collider. To characterize ground motion on relevant time scales, measurements have been performed at three geologically different locations using a hydrostatic level system developed specifically for these studies. Comparative results from the different sites are presented in this paper.

Long-term Stability of a Camouflage Retreatment of an Asymmetric Class III/Posterior Open Bite Using Sliding Jigs.

PubMed

Oliveira, Dauro Douglas; de Oliveira, Bruno Franco; Figueiredo, Daniel Santos Fonseca; Antunes, Alberto Nogueira da Gama; Seraidarian, Paulo Isaías

2017-10-01

This article reports the camouflage retreatment of an adult patient presenting an asymmetric Class III malocclusion and posterior open bite. Sliding jigs (SJs) associated with intermaxillary elastics were used. The long-term stability of the excellent results suggests that the use of SJs to correct asymmetric posterior occlusions may be effective.

Application of long-term simulation programs for analysis of system islanding

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

Sancha, J.L.; Llorens, M.L.; Moreno, J.M.

1997-02-01

This paper describes the main results and conclusions from the application of two different long-term stability programs to the analysis of a system islanding scenario for a study case developed by Red Electrica de Espana (REE), based on the Spanish system. Two main goals were to evaluate the performance of both the influence of some important control and protection elements (tie-line loss-of-synchronism relays, underfrequency load-shedding, load-frequency control, and power plant dynamics). Conclusions about modeling and computational requirements for system islanding (frequency) scenarios and use of long-term stability programs are presented.

Recombination and phenotype evolution dynamics of Helicobacter pylori in colonized hosts.

PubMed

Shafiee, Ahmad; Amini, Massoud; Emamirad, Hassan; Abadi, Amin Talebi Bezmin

2016-07-01

The ample genetic diversity and variability of Helicobater pylori, and therefore its phenotypic evolution, relate not only to frequent mutation and selection but also to intra-specific recombination. Webb and Blaser applied a mathematical model to distinguish the role of selection and mutation for Lewis antigen phenotype evolution during long-term gastric colonization in infected animal hosts (mice and gerbils). To investigate the role of recombination in Lewis antigen phenotype evolution, we have developed a prior population dynamic by adding recombination term to the model. We simulate and interpret the new model simulation's results with a comparative analysis of biological aspects. The main conclusions are as follows: (i) the models and consequently the hosts with higher recombination rate require a longer time for stabilization; and (ii) recombination and mutation have opposite effects on the size of H. pylori populations with phenotypes in the range of the most-fit ones (i.e. those that have a selective advantage) due to natural selection, although both can increase phenotypic diversity.

Long-Term Variations of the EOP and ICRF2

NASA Technical Reports Server (NTRS)

Zharov, Vladimir; Sazhin, Mikhail; Sementsov, Valerian; Sazhina, Olga

2010-01-01

We analyzed the time series of the coordinates of the ICRF radio sources. We show that part of the radio sources, including the defining sources, shows a significant apparent motion. The stability of the celestial reference frame is provided by a no-net-rotation condition applied to the defining sources. In our case this condition leads to a rotation of the frame axes with time. We calculated the effect of this rotation on the Earth orientation parameters (EOP). In order to improve the stability of the celestial reference frame we suggest a new method for the selection of the defining sources. The method consists of two criteria: the first one we call cosmological and the second one kinematical. It is shown that a subset of the ICRF sources selected according to cosmological criteria provides the most stable reference frame for the next decade.

New kind of injection-locked oscillator and its corresponding long-term stability control.

PubMed

Hong, Jun; Liu, An; Wang, Xiao-hu; Yao, Sheng-xing; Li, Zu-ling

2015-09-20

A new type of opto-electronic hybrid oscillator is proposed for the first time, to the best of our knowledge, and verified by experiments in this paper. Typical electronic oscillator-dielectric resonator oscillator as the first injection source is used to injection lock the first long-fiber loop-based opto-electronic oscillator (OEO); then its output is used to injection lock the second long-fiber opto-electronic oscillator. Using this method, low-phase noise output signal can be obtained. Experiments show that single side-band (SSB) phase noise of a 9.5 GHz oscillation signal at 10 kHz offset frequency decreases from -123 to -135  dBc/Hz after the first injection, then, through the second injection, the SSB phase noise drops down to -146  dBc/Hz. In order to solve the long-term stability problem of the above oscillator, a new stability-control circuit also is designed and verified by experiments. Experiments show that the Allan deviation decreases from 9.0×10(-11) to 2.2×10(-12) during 1 s after the long-term stability-control circuit being used.

Long-term monitoring of stream bank stability under different vegetation cover

NASA Astrophysics Data System (ADS)

Krzeminska, Dominika; Skaalsveen, Kamilla; Kerkhof, Tjibbe

2017-04-01

Vegetated buffer zones are common environmental measures in many countries, including Norway. The presence of riparian vegetation on stream banks not only provides ecological benefits but also influence bank slope stability, through several complex interactions between riparian vegetation and hydro - mechanical processes. The hydrological processes associated with slope stability are complex and yet difficult to quantify, especially because their transient effects (e.g. changes throughout the vegetation life cycle). Additionally, there is very limited amount of field scale research focusing on investigation of coupled hydrological and mechanical influence of vegetation on stream bank behavior, accounting for both seasonal time scale and different vegetation type, and none dedicated to marine clay soils (typically soil for Norway). In order to fill this gap we established continues, long term hydrogeological monitoring o selected cross - section within stream bank, covered with different types of vegetation, typical for Norwegian agriculture areas (grass, shrubs, and trees). The monitoring involves methods such as spatial and temporal monitoring of soil moisture conditions, ground water level and fluctuation of water level in the stream. Herein we will present first 10 months of monitoring data: observed hydrological trends and differences between three cross - sections. Moreover, we will present first modelling exercises that aims to estimate stream banks stability with accounting on presence of different vegetation types using BSTEM and HYDRUS models. With this presentation, we would like to stimulate the discussion and get feedback that could help us to improve both, our experimental set up and analysis approach.

Integrating tristimulus colorimetry into pharmaceutical development for color selection and physical appearance control: a quality-by-design approach.

PubMed

Hetrick, Evan M; Vannoy, Jeffrey; Montgomery, Laura L; Pack, Brian W

2013-08-01

The color of pharmaceutical dosage forms can be an important aspect of product branding and patient compliance with a dosing regimen. During the development of drug products, it is important to understand the stability of not only the active pharmaceutical ingredient but also the color and appearance of the tablet or capsule. Currently, the most common method to ensure color stability is to conduct a visual test throughout a stability study. This visual test is subjective and can be expensive, especially if there is a failure late in development or after marketing approval. This work describes a series of studies using accelerated conditions (i.e., heat, humidity, and light) and logistic regression analyses that have been developed to determine the relative stability ranking of multiple color coatings early in development to provide an increased probability of technical success on long-term stability studies and to avoid coatings whose visual appearance may change over time. Once this relative stability ranking has been established, the stability advantages can be assessed versus any manufacturing/processing liabilities of the selected coating in order to make a data-driven decision around coating selection. This work reviews the basic fundamentals of colorimetry, followed by the description of a consistent experimental approach to correlate a visual rating with an instrumental measurement (e.g., dE(*) from a colorimeter) to remove the subjectivity from the assessment. This approach represents a novel strategy for establishing a probabilized correlation between the quantitative instrumental color measurement and the visual rating of the same color change. Copyright © 2013 Wiley Periodicals, Inc.

Electrodes for Semiconductor Gas Sensors

PubMed Central

Lee, Sung Pil

2017-01-01

The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. PMID:28346349

Long term in vitro stability of fully integrated wireless neural interfaces based on Utah slant electrode array

NASA Astrophysics Data System (ADS)

Sharma, Asha; Rieth, Loren; Tathireddy, Prashant; Harrison, Reid; Solzbacher, Florian

2010-02-01

We herein report in vitro functional stability and recording longevity of a fully integrated wireless neural interface (INI). The INI uses biocompatible Parylene-C as an encapsulation layer, and was immersed in phosphate buffered saline (PBS) for a period of over 150 days. The full functionality (wireless radio-frequency power, command, and signal transmission) and the ability of INI to record artificial action potentials even after 150 days of PBS soaking without any change in signal/noise amplitude constitutes a major milestone in long term stability, and evaluate the encapsulation reliability, functional stability, and potential usefulness for future chronic implants.

Inter-laboratory comparison of elemental analysis and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Part I: delta13C measurements of selected compounds for the development of an isotopic Grob-test.

PubMed

Serra, F; Janeiro, A; Calderone, G; Rojas, J M Moreno; Rhodes, C; Gonthier, L A; Martin, F; Lees, M; Mosandl, A; Sewenig, S; Hener, U; Henriques, B; Ramalho, L; Reniero, F; Teixeira, A J; Guillou, C

2007-03-01

This study was directed towards investigating suitable compounds to be used as stable isotope reference materials for gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) calibration. Several compounds were selected from those used in the 'Grob-test' mixture. Oxygen- and nitrogen-containing substances were added to these compounds to allow the mixture to be used as a possible multi-isotopic calibration tool for 2H/1H, 13C/12C, 15N/14N and 18O/16O ratio determinations. In this paper we present the results of delta13C measurements performed by the consortium of the five laboratories taking part in this inter-calibration exercise. All the compounds were individually assessed for homogeneity, short-term stability and long-term stability by means of EA-IRMS, as required by the bureau communitaire de reference (BCR) Guide for Production of Certified Reference Materials. The results were compared then with the GC-C-IRMS measurements using both polar and non-polar columns, and the final mixture of selected compounds underwent a further certification exercise assessing limits of accuracy and reproducibility under specified GC-C-IRMS conditions. Copyright 2007 John Wiley & Sons, Ltd.

The role of silica nanoparticles on long-term room-temperature stabilization of water-in-oil emulsions containing microalgae.

PubMed

Fernández, L; Scher, H; VanderGheynst, J S

2015-12-01

Prior research has demonstrated that microalgae can be stored for extended periods of time at room temperature in water-in-oil (W/O) emulsions stabilized by surface modified silica nanoparticles. However, little research has been done to examine the impact of nanoparticle concentration on emulsion stability. Such information is important for large-scale production of emulsions for microalgae storage and delivery. Studies were done to examine the impact of silica nanoparticle concentration on emulsion stability and identify the lower limit for nanoparticle concentration. Emulsion physical stability was determined using internal phase droplet size measurements and biological stability was evaluated using cell density measurements. The results demonstrate that nanoparticle concentrations as low as 0·5wt% in the oil phase can be used without significant losses in emulsion stability and microalgae viability. Stabilization technologies are needed for long-term storage and application of microalgae in agricultural-scale systems. While prior work has demonstrated that water-in-oil emulsions containing silica nanoparticles offer a promising solution for long-term microalgae storage at room temperature, little research has been done to examine the impact of nanoparticle concentration on emulsion stability. Here, we show the effects of silica nanoparticle concentration on maintaining physical stability of emulsions and sustaining viable cells. The results enable informed decisions to be made regarding production of emulsions containing silica nanoparticles and associated impacts on stabilization of microalgae. © 2015 The Society for Applied Microbiology.

Monitoring on-orbit calibration stability of the Terra MODIS and Landsat 7 ETM+ sensors using pseudo-invariant test sites

USGS Publications Warehouse

Chander, G.; Xiong, X.(J.); Choi, T.(J.); Angal, A.

2010-01-01

The ability to detect and quantify changes in the Earth's environment depends on sensors that can provide calibrated, consistent measurements of the Earth's surface features through time. A critical step in this process is to put image data from different sensors onto a common radiometric scale. This work focuses on monitoring the long-term on-orbit calibration stability of the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors using the Committee on Earth Observation Satellites (CEOS) reference standard pseudo-invariant test sites (Libya 4, Mauritania 1/2, Algeria 3, Libya 1, and Algeria 5). These sites have been frequently used as radiometric targets because of their relatively stable surface conditions temporally. This study was performed using all cloud-free calibrated images from the Terra MODIS and the L7 ETM+ sensors, acquired from launch to December 2008. Homogeneous regions of interest (ROI) were selected in the calibrated images and the mean target statistics were derived from sensor measurements in terms of top-of-atmosphere (TOA) reflectance. For each band pair, a set of fitted coefficients (slope and offset) is provided to monitor the long-term stability over very stable pseudo-invariant test sites. The average percent differences in intercept from the long-term trends obtained from the ETM + TOA reflectance estimates relative to the MODIS for all the CEOS reference standard test sites range from 2.5% to 15%. This gives an estimate of the collective differences due to the Relative Spectral Response (RSR) characteristics of each sensor, bi-directional reflectance distribution function (BRDF), spectral signature of the ground target, and atmospheric composition. The lifetime TOA reflectance trends from both sensors over 10 years are extremely stable, changing by no more than 0.4% per year in its TOA reflectance over the CEOS reference standard test sites.

Large variability of biochar stability and biochar properties

NASA Astrophysics Data System (ADS)

Lehmann, J.; Nguyen, B.; Hanley, K.; Enders, A.

2008-12-01

In general, charring or purposeful pyrolysis increases the stability of biomass. It is less clear, however, to what extent biochar properties influence its stability. Chemical and physical properties of biochars and biomass-derived black carbons (BC) vary greatly as a function of the type of biomass it was generated from and of the production temperature. We show that these properties greatly affect the stability of BC is a function of both these factors, with highly significant interactions. BC produced from corn stalks produced at 350°C decomposed much quicker when incubated at field capacity at 30°C for one year than those produced at 600°C. In contrast, there was hardly a difference noted between those two temperatures if oak was the precursor biomass. Such differences in labile carbon not only affect the proportion of stable carbon in BC, but also influence the quantification of long-term stability. Extrapolation from short-term decay to long-term stability may require prior knowledge about the decay rate of the labile fraction of BC. Some indications are provided for the short-term oxidation of BC.

Dynamics of morphological evolution in experimental Escherichia coli populations.

PubMed

Cui, F; Yuan, B

2016-08-30

Here, we applied a two-stage clonal expansion model of morphological (cell-size) evolution to a long-term evolution experiment with Escherichia coli. Using this model, we derived the incidence function of the appearance of cell-size stability, the waiting time until this morphological stability, and the conditional and unconditional probabilities of morphological stability. After assessing the parameter values, we verified that the calculated waiting time was consistent with the experimental results, demonstrating the effectiveness of the two-stage model. According to the relative contributions of parameters to the incidence function and the waiting time, cell-size evolution is largely determined by the promotion rate, i.e., the clonal expansion rate of selectively advantageous organisms. This rate plays a prominent role in the evolution of cell size in experimental populations, whereas all other evolutionary forces were found to be less influential.

Development of a High-Stability Microstrip-based L-band Radiometer for Ocean Salinity Measurements

NASA Technical Reports Server (NTRS)

Pellerano, Fernando A.; Horgan, Kevin A.; Wilson, William J.; Tanner, Alan B.

2004-01-01

The development of a microstrip-based L-band Dicke radiometer with the long-term stability required for future ocean salinity measurements to an accuracy of 0.1 psu is presented. This measurement requires the L-band radiometers to have calibration stabilities of less than or equal to 0.05 K over 2 days. This research has focused on determining the optimum radiometer requirements and configuration to achieve this objective. System configuration and component performance have been evaluated with radiometer test beds at both JPL and GSFC. The GSFC testbed uses a cryogenic chamber that allows long-term characterization at radiometric temperatures in the range of 70 - 120 K. The research has addressed several areas including component characterization as a function of temperature and DC bias, system linearity, optimum noise diode injection calibration, and precision temperature control of components. A breadboard radiometer, utilizing microstrip-based technologies, has been built to demonstrate this long-term stability.

Long-term maintenance of the carrier-envelope phase coherence of a femtosecond laser.

PubMed

Kim, Eok Bong; Lee, Jae-Hwan; Lee, Won-Kyu; Luu, Tran Trung; Nam, Chang Hee

2010-12-06

The long-term carrier-envelope phase (CEP) coherence of a femtosecond laser with same pulse-to-pulse CEP value, obtained using the direct locking method, is demonstrated by employing a quasi-common-path interferometer (QPI). For the evaluation of the CEP stability, the phase noise properties of a femtosecond laser with the CEP stabilized using a QPI are compared with those obtained using a Mach-Zehnder f-2f interferometer, for which the phase power spectral density and the Allan deviation were calculated from the beat signals of the interferometers. With the improved CEP stability, the long-term CEP coherent signal with an accumulated phase noise well below 1 radian can be maintained for more than 56 hours, i.e., the CEP coherence is preserved without a phase cycle slip for more than 1.6 × 10(13) pulses at a repetition rate of 80 MHz. The relative stability is also estimated to be approximately 1.4 × 10(-22) at a central wavelength of 790 nm.

Influence of the dynamic Stark effect on long-term frequency stability of a self-oscillating magnetometer with laser-pumped alkali atoms

NASA Astrophysics Data System (ADS)

Baranov, A. A.; Ermak, S. V.; Kulachenkov, N. K.; Petrenko, M. V.; Sagitov, E. A.; Semenov, V. V.

2017-11-01

This paper presents the results of investigation Stark shift effect influence on the long-term stability of a dual scheme of quantum magnetometers. Such scheme allows suppressing Stark shift components when a certain pumping light polarization is applied. As a result, long-term stability of a quantum sensor increases. However, when low-frequency (LF) and microwave fields are attached to a single vapor cell a coherence circulation in hyperfine structure of alkali atoms takes place. Physical origin of this effect is associated with the so called “dressed” atom theory, when atom is “dressed” by LF field. It yields in multiphoton absorption and resonance frequency shift. First estimates for this shift based on density matrix evolution formalism are provided in the paper.

Long-term stable active mount for reflective optics

NASA Astrophysics Data System (ADS)

Reinlein, C.; Brady, A.; Damm, C.; Mohaupt, M.; Kamm, A.; Lange, N.; Goy, M.

2016-07-01

We report on the development of an active mount with an orthogonal actuator matrix offering a stable shape optimization for gratings or mirrors. We introduce the actuator distribution and calculate the accessible Zernike polynomials from their actuator influence function. Experimental tests show the capability of the device to compensate for aberrations of grating substrates as we report measurements of a 110x105 mm2 and 220x210 mm2 device With these devices, we evaluate the position depending aberrations, long-term stability shape results, and temperature-induced shape variations. Therewith we will discuss potential applications in space telescopes and Earth-based facilities where long-term stability is mandatory.

Global long-term ozone trends derived from different observed and modelled data sets

NASA Astrophysics Data System (ADS)

Coldewey-Egbers, M.; Loyola, D.; Zimmer, W.; van Roozendael, M.; Lerot, C.; Dameris, M.; Garny, H.; Braesicke, P.; Koukouli, M.; Balis, D.

2012-04-01

The long-term behaviour of stratospheric ozone amounts during the past three decades is investigated on a global scale using different observed and modelled data sets. Three European satellite sensors GOME/ERS-2, SCIAMACHY/ENVISAT, and GOME-2/METOP are combined and a merged global monthly mean total ozone product has been prepared using an inter-satellite calibration approach. The data set covers the 16-years period from June 1995 to June 2011 and it exhibits an excellent long-term stability, which is required for such trend studies. A multiple linear least-squares regression algorithm using different explanatory variables is applied to the time series and statistically significant positive trends are detected in the northern mid latitudes and subtropics. Global trends are also estimated using a second satellite-based Merged Ozone Data set (MOD) provided by NASA. For few selected geographical regions ozone trends are additionally calculated using well-maintained measurements of individual Dobson/Brewer ground-based instruments. A reasonable agreement in the spatial patterns of the trends is found amongst the European satellite, the NASA satellite, and the ground-based observations. Furthermore, two long-term simulations obtained with the Chemistry-Climate Models E39C-A provided by German Aerospace Center and UMUKCA-UCAM provided by University of Cambridge are analysed.

Note: Improving long-term stability of hot-wire anemometer sensors by means of annealing

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

Lundström, H., E-mail: hans.lundstrom@hig.se

2015-08-15

Annealing procedures for hot-wire sensors of platinum and platinum-plated tungsten have been investigated experimentally. It was discovered that the two investigated sensor metals behave quite differently during the annealing process, but for both types annealing may improve long-term stability considerably. Measured drift of sensors both without and with prior annealing is presented. Suggestions for suitable annealing temperatures and times are given.

Long-term Stabilization of Disturbed Slopes Resulting from Construction Operations

DOT National Transportation Integrated Search

2018-01-01

Highway construction disturbs soil, which must be stabilized to prevent migration of soil particles into water bodies. Stabilization is enforced by law, regulation, and a permit system. Stabilization is most efficiently attained by reestablishment of...

Social evolution and genetic interactions in the short and long term.

PubMed

Van Cleve, Jeremy

2015-08-01

The evolution of social traits remains one of the most fascinating and feisty topics in evolutionary biology even after half a century of theoretical research. W.D. Hamilton shaped much of the field initially with his 1964 papers that laid out the foundation for understanding the effect of genetic relatedness on the evolution of social behavior. Early theoretical investigations revealed two critical assumptions required for Hamilton's rule to hold in dynamical models: weak selection and additive genetic interactions. However, only recently have analytical approaches from population genetics and evolutionary game theory developed sufficiently so that social evolution can be studied under the joint action of selection, mutation, and genetic drift. We review how these approaches suggest two timescales for evolution under weak mutation: (i) a short-term timescale where evolution occurs between a finite set of alleles, and (ii) a long-term timescale where a continuum of alleles are possible and populations evolve continuously from one monomorphic trait to another. We show how Hamilton's rule emerges from the short-term analysis under additivity and how non-additive genetic interactions can be accounted for more generally. This short-term approach reproduces, synthesizes, and generalizes many previous results including the one-third law from evolutionary game theory and risk dominance from economic game theory. Using the long-term approach, we illustrate how trait evolution can be described with a diffusion equation that is a stochastic analogue of the canonical equation of adaptive dynamics. Peaks in the stationary distribution of the diffusion capture classic notions of convergence stability from evolutionary game theory and generally depend on the additive genetic interactions inherent in Hamilton's rule. Surprisingly, the peaks of the long-term stationary distribution can predict the effects of simple kinds of non-additive interactions. Additionally, the peaks capture both weak and strong effects of social payoffs in a manner difficult to replicate with the short-term approach. Together, the results from the short and long-term approaches suggest both how Hamilton's insight may be robust in unexpected ways and how current analytical approaches can expand our understanding of social evolution far beyond Hamilton's original work. Copyright © 2015 Elsevier Inc. All rights reserved.

New getter configuration at wafer level for assuring long term stability of MEMs

NASA Astrophysics Data System (ADS)

Moraja, Marco; Amiotti, Marco; Kullberg, Richard C.

2003-01-01

The evolution from ceramic packages to wafer to wafer hermetic sealing poses tremendous technical challenges to integrate a proper getter inside the MEMs to assure a long term stability and reliability of the devices. The state of the art solution to integrate a getter inside the MEMs of the last generation consists in patterning the getter material with a specific geometry onto the Si cap wafer. The practical implementation of this solution consists in a 4" or 6" Si wafers with grooves or particular incisures, where the getter material is placed in form of a thick film. The typical thickness of these thick films is in the range of few microns, depending on the gas load to be handled during the lifetime of the device. The structure of the thick getter film is highly porous in order to improve sorption performances, but at the same time there are no loose particles thanks to a proprietary manufacturing method. The getter thick film is composed of a Zr special alloy with a proper composition to optimize the sorption performances. The getter thick film can be placed selectively into grooves without affecting the lateral regions, surrounding the grooves where the hermetic sealing is performed.

Long-term stability of radiotherapy dosimeters calibrated at the Polish Secondary Standard Dosimetry Laboratory.

PubMed

Ulkowski, Piotr; Bulski, Wojciech; Chełmiński, Krzysztof

2015-10-01

Unidos 10001, Unidos E (10008/10009) and Dose 1 electrometers from 14 radiotherapy centres were calibrated 3-4 times over a long period of time, together with Farmer type (PTW 30001, 30013, Nuclear Enterprises 2571 and Scanditronix-Wellhofer FC65G) cylindrical ionization chambers and plane-parallel type chambers (PTW Markus 23343 and Scanditronix-Wellhofer PPC05). On the basis of the long period of repetitive establishing of calibration coefficients for the same electrometers and ionization chambers, the accuracy of electrometers and the long-term stability of ionization chambers were examined. All measurements were carried out at the same laboratory, by the same staff, according to the same IAEA recommendations. A good accuracy and long-term stability of the dosimeters used in Polish radiotherapy centres was observed. These values were within 0.1% for electrometers and 0.2% for the chambers with electrometers. Furthermore, these values were not observed to vary over time. The observations confirm the opinion that the requirement of calibration of the dosimeters more often than every 2 years is not justified. Copyright © 2015 Elsevier Ltd. All rights reserved.

Upweighting rare favourable alleles increases long-term genetic gain in genomic selection programs.

PubMed

Liu, Huiming; Meuwissen, Theo H E; Sørensen, Anders C; Berg, Peer

2015-03-21

The short-term impact of using different genomic prediction (GP) models in genomic selection has been intensively studied, but their long-term impact is poorly understood. Furthermore, long-term genetic gain of genomic selection is expected to improve by using Jannink's weighting (JW) method, in which rare favourable marker alleles are upweighted in the selection criterion. In this paper, we extend the JW method by including an additional parameter to decrease the emphasis on rare favourable alleles over the time horizon, with the purpose of further improving the long-term genetic gain. We call this new method dynamic weighting (DW). The paper explores the long-term impact of different GP models with or without weighting methods. Different selection criteria were tested by simulating a population of 500 animals with truncation selection of five males and 50 females. Selection criteria included unweighted and weighted genomic estimated breeding values using the JW or DW methods, for which ridge regression (RR) and Bayesian lasso (BL) were used to estimate marker effects. The impacts of these selection criteria were compared under three genetic architectures, i.e. varying numbers of QTL for the trait and for two time horizons of 15 (TH15) or 40 (TH40) generations. For unweighted GP, BL resulted in up to 21.4% higher long-term genetic gain and 23.5% lower rate of inbreeding under TH40 than RR. For weighted GP, DW resulted in 1.3 to 5.5% higher long-term gain compared to unweighted GP. JW, however, showed a 6.8% lower long-term genetic gain relative to unweighted GP when BL was used to estimate the marker effects. Under TH40, both DW and JW obtained significantly higher genetic gain than unweighted GP. With DW, the long-term genetic gain was increased by up to 30.8% relative to unweighted GP, and also increased by 8% relative to JW, although at the expense of a lower short-term gain. Irrespective of the number of QTL simulated, BL is superior to RR in maintaining genetic variance and therefore results in higher long-term genetic gain. Moreover, DW is a promising method with which high long-term genetic gain can be expected within a fixed time frame.

Long term stability of Oligo (dT) 25 magnetic beads for the expression analysis of Euglena gracilis for long term space projects

NASA Astrophysics Data System (ADS)

Becker, Ina; Strauch, Sebastian M.; Hauslage, Jens; Lebert, Michael

2017-05-01

The unicellular freshwater flagellate Euglena gracilis has a highly developed sensory system. The cells use different stimuli such as light and gravity to orient themselves in the surrounding medium to find areas for optimal growth. Due to the ability to produce oxygen and consume carbon dioxide, Euglena is a suitable candidate for life support systems. Participation in a long-term space experiment would allow for the analysis of changes and adaptations to the new environment, and this could bring new insights into the mechanism of perception of gravity and the associated signal transduction chain. For a molecular analysis of transcription patterns, an automated system is necessary, capable of performing all steps from taking a sample, processing it and generating data. One of the developmental steps is to find long-term stable reagents and materials and test them for stability at higher-than-recommended temperature conditions during extended storage time. We investigated the usability of magnetic beads in an Euglena specific lysis buffer after addition of the RNA stabilizer Dithiothreitol over 360 days and the lysis buffer with the stabilizer alone over 455 days at the expected storage temperature of 19 °C. We can claim that the stability is not impaired at all after an incubation period of over one year. This might be an interesting result for researchers who have to work under non-standard lab conditions, as in biological or medicinal fieldwork.

Evolution of long-term coloration trends with biochemically unstable ingredients

PubMed Central

Davis, Sarah N.; Andrews, John E.; Badyaev, Alexander V.

2016-01-01

The evolutionarily persistent and widespread use of carotenoid pigments in animal coloration contrasts with their biochemical instability. Consequently, evolution of carotenoid-based displays should include mechanisms to accommodate or limit pigment degradation. In birds, this could involve two strategies: (i) evolution of a moult immediately prior to the mating season, enabling the use of particularly fast-degrading carotenoids and (ii) evolution of the ability to stabilize dietary carotenoids through metabolic modification or association with feather keratins. Here, we examine evolutionary lability and transitions between the two strategies across 126 species of birds. We report that species that express mostly unmodified, fast-degrading, carotenoids have pre-breeding moults, and a particularly short time between carotenoid deposition and the subsequent breeding season. Species that expressed mostly slow-degrading carotenoids in their plumage accomplished this through increased metabolic modification of dietary carotenoids, and the selective expression of these slow-degrading compounds. In these species, the timing of moult was not associated with carotenoid composition of plumage displays. Using repeated samples from individuals of one species, we found that metabolic modification of dietary carotenoids significantly slowed their degradation between moult and breeding season. Thus, the most complex and colourful ornamentation is likely the most biochemically stable in birds, and depends less on ecological factors, such as moult timing and migration tendency. We suggest that coevolution of metabolic modification, selective expression and biochemical stability of plumage carotenoids enables the use of unstable pigments in long-term evolutionary trends in plumage coloration. PMID:27194697

Development of a Hard X-ray Beam Position Monitor for Insertion Device Beams at the APS

NASA Astrophysics Data System (ADS)

Decker, Glenn; Rosenbaum, Gerd; Singh, Om

2006-11-01

Long-term pointing stability requirements at the Advanced Photon Source (APS) are very stringent, at the level of 500 nanoradians peak-to-peak or better over a one-week time frame. Conventional rf beam position monitors (BPMs) close to the insertion device source points are incapable of assuring this level of stability, owing to mechanical, thermal, and electronic stability limitations. Insertion device gap-dependent systematic errors associated with the present ultraviolet photon beam position monitors similarly limit their ability to control long-term pointing stability. We report on the development of a new BPM design sensitive only to hard x-rays. Early experimental results will be presented.

A predictive radiological analysis of short stems versus both shortened and long stems in primary hip replacement: A case-control study of 100 cases of Metha versus ABG II and Omnifit HA at 2-8years' follow-up.

PubMed

Epinette, J-A; Brax, M; Chammaï, Y

2017-11-01

Short hip stems, intended to conserve bone stock and ensure a more physiological distribution of stress in the femur under loading, are meeting with renewed interest. Radiologic semiology is not known exactly, particularly in relation to conventional implants; we therefore conducted a case-control study of 3 types of implant differing only in stem length: short, shortened or long. The aim was: (1) to compare radiographic aspects, (2) to attempt to systematize medium-term radiologic status for the 3 types, and (3) to assess the impact of radiographic aspect on loosening and revision rates. The short Metha stem is better adapted to the recipient bone than longer stems, without sacrificing stability. A prospective series comprising the first 100 selected cases of hip replacement using the short Metha stem was compared to two other series of 100 "long" (Omnifit HA) and 100 "shortened" (ABG II) stems at comparable follow-up: 4.05±1.44years (range: 2-8years) for Metha, 4.48±0.97years (range: 2-8years) for Omnifit, and 4.75±2.07years (range: 2-8years) for ABG II. Selection criteria in this initial phase were very strict: young age and/or high activity level, with good bone stock and femoral morphology suited to fitting a Metha stem (no "stovepipe" or "champagne-flute" femurs), for which 12.8% of primary hip replacements were selected. Matching was performed by sampling on criteria of age, gender, body-mass index and etiology. Radiographic parameters were compared between the short stem group and the two control groups and classified according to Engh-Massin score (10 points for fixation and 17 for stability). The short Metha stem provided excellent fixation scores: 7.65/10, versus 7.16 (P=0.003) and 5.92 (P=0.0001) for ABG II and Omnifit, respectively. Likewise, stability was scored 14.23/17 for Metha, vs. 14.51 (NS) and 11.83 (P=0.0001) respectively, and the total score was higher for Metha (21.88/27) than ABG II (21.67; P=0.03) or, more particularly, Omnifit (17.83; P=0.0001). The Metha stem was never associated with thigh pain or periprosthetic fracture. 8-year survival was 100%, without significant difference with respect to ABG II (100%; NS) or Omnifit (98.8%; 95% CI: 0.964-1; NS). The apparent radiologic superiority of the short Metha stem requires long-term confirmation in non-selected series. Meanwhile, Metha can be asserted to have demonstrated optimal compromise between lasting bone anchorage and respect of bone physiology under loading at medium term. III, case-control study. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

An evolutionary model to predict the frequency of antibiotic resistance under seasonal antibiotic use, and an application to Streptococcus pneumoniae

PubMed Central

Lehtinen, Sonja; Fraser, Christophe

2017-01-01

The frequency of resistance to antibiotics in Streptococcus pneumoniae has been stable over recent decades. For example, penicillin non-susceptibility in Europe has fluctuated between 12% and 16% without any major time trend. In spite of long-term stability, resistance fluctuates over short time scales, presumably in part due to seasonal fluctuations in antibiotic prescriptions. Here, we develop a model that describes the evolution of antibiotic resistance under selection by multiple antibiotics prescribed at seasonally changing rates. This model was inspired by, and fitted to, published data on monthly antibiotics prescriptions and frequency of resistance in two communities in Israel over 5 years. Seasonal fluctuations in antibiotic usage translate into small fluctuations of the frequency of resistance around the average value. We describe these dynamics using a perturbation approach that encapsulates all ecological and evolutionary forces into a generic model, whose parameters quantify a force stabilizing the frequency of resistance around the equilibrium and the sensitivity of the population to antibiotic selection. Fitting the model to the data revealed a strong stabilizing force, typically two to five times stronger than direct selection due to antibiotics. The strong stabilizing force explains that resistance fluctuates in phase with usage, as antibiotic selection alone would result in resistance fluctuating behind usage with a lag of three months when antibiotic use is seasonal. While most antibiotics selected for increased resistance, intriguingly, cephalosporins selected for decreased resistance to penicillins and macrolides, an effect consistent in the two communities. One extra monthly prescription of cephalosporins per 1000 children decreased the frequency of penicillin-resistant strains by 1.7%. This model emerges under minimal assumptions, quantifies the forces acting on resistance and explains up to 43% of the temporal variation in resistance. PMID:28566489

CW injection locking for long-term stability of frequency combs

NASA Astrophysics Data System (ADS)

Williams, Charles; Quinlan, Franklyn; Delfyett, Peter J.

2009-05-01

Harmonically mode-locked semiconductor lasers with external ring cavities offer high repetition rate pulse trains while maintaining low optical linewidth via long cavity storage times. Continuous wave (CW) injection locking further reduces linewidth and stabilizes the optical frequencies. The output can be stabilized long-term with the help of a modified Pound-Drever-Hall feedback loop. Optical sidemode suppression of 36 dB has been shown, as well as RF supermode noise suppression of 14 dB for longer than 1 hour. In addition to the injection locking of harmonically mode-locked lasers requiring an external frequency source, recent work shows the viability of the injection locking technique for regeneratively mode-locked lasers, or Coupled Opto-Electronic Oscillators (COEO).

Long-term outcome of sporadic and FAP-associated desmoid tumors treated with high-dose selective estrogen receptor modulators and sulindac: a single-center long-term observational study in 134 patients.

PubMed

Quast, Daniel Robert; Schneider, Ralph; Burdzik, Emanuel; Hoppe, Steffen; Möslein, Gabriela

2016-01-01

Aim of this study is to evaluate the outcome of long-term conservative treatment with sulindac and high-dose selective estrogen receptor modulators (SERMs) for sporadic and FAP-associated desmoid tumors. Desmoids are very rare tumors in the general population but occur frequently in FAP patients, being encountered in 23-38 %. Treatment of desmoids is still most controversial since response cannot be predicted and they are prone to develop recurrence. This study included all desmoid patients that were treated and followed at our institution and had completed at least 1 year of treatment. Response was defined as stable size or regression of desmoid size between two CT or MRI scans. A total of 134 patients were included. 64 (47.8 %) patients had a confirmed diagnosis of FAP, 69 (51.5 %) patients were sporadic. Overall 114 (85.1 %) patients showed regressive or stable desmoid size. Patients with previous history of multiple desmoid-related surgeries showed less-favorable response. The mean time to reach at least stable size was 14.9 (±9.1) months. After regression or stabilization, medication was tapered in 69 (60.5 %) of the treated patients with only one long-term recurrence after >10 years. The results of this study fortify the role of sulindac and high-dose SERMs as an effective and safe treatment for both, sporadic and FAP-associated desmoid tumors. While invasive treatment frequently results in high recurrence rates, high morbidity and high mortality, this conservative treatment is successful in most patients. The recurrence rate is negligible with no desmoid-related mortality in this large series. Therefore surgical resection, especially for mesenteric desmoids, should be deferred favoring this convincingly effective, well tolerated regimen.

A Model of Consumer Decision Making in the Selection of a Long-Term Care Facility.

ERIC Educational Resources Information Center

Neugroschel, William J.; Notzon, Linda R.

Since nursing home placement is frequently the last choice for families of elderly people who need long-term care, little literature exists which delineates a model for consumer decision making in the selection of a specific long-term care facility. Critical issues include the following: (1) who actually makes the selection; (2) what other…

The impact of experimental measurement errors on long-term viscoelastic predictions. [of structural materials

NASA Technical Reports Server (NTRS)

Tuttle, M. E.; Brinson, H. F.

1986-01-01

The impact of flight error in measured viscoelastic parameters on subsequent long-term viscoelastic predictions is numerically evaluated using the Schapery nonlinear viscoelastic model. Of the seven Schapery parameters, the results indicated that long-term predictions were most sensitive to errors in the power law parameter n. Although errors in the other parameters were significant as well, errors in n dominated all other factors at long times. The process of selecting an appropriate short-term test cycle so as to insure an accurate long-term prediction was considered, and a short-term test cycle was selected using material properties typical for T300/5208 graphite-epoxy at 149 C. The process of selection is described, and its individual steps are itemized.

Long-term stability of GOES-8 and -9 attitude control

NASA Astrophysics Data System (ADS)

Carr, James L.

1996-10-01

An independent audit of the in-orbit behavior of the GOES-8 and GOES-9 satellites has been conducted for the NASA/GSFC. This audit utilized star and landmark observations from the GOES imager to determine long-term histories for spacecraft attitude, orbital position, and instrument internal misalignments. The paper presents results from this audit. Long-term drifts are found in the attitude histories, whereas the misalignment histories are shown to be diurnally stable. The GOES image navigation and registration system is designed to compensate for instrument internal misalignments, and both the diurnally repeatable and drift components of the attitude. Correlations between GOES-8 and GOES-9 long-term roll and pitch drifts implicate the Earth sensor as the origin of these observed drifts. This results clearly demonstrates the enhanced registration stability to be obtained with stellar inertial attitude determination replacing or supplementing Earth sensor control on future GOES missions.

Effect of hydrogen on the strength and microstructure of selected ceramics

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.; Hull, David R.; Misra, Ajay K.

1990-01-01

Ceramics in monolithic form and as composite constituents in the form of fibers, matrices, and coatings are currently being considered for a variety of high-temperature applications in aeronautics and space. Many of these applications involve exposure to a hydrogen-containing environment. The compatibility of selected ceramics in gaseous high-temperature hydrogen is assessed. Environmental stability regimes for the long term use of ceramic materials are defined by the parameters of temperature, pressure, and moisture content. Thermodynamically predicted reactions between hydrogen and several monolithic ceramics are compared with actual performance in a controlled environment. Morphology of hydrogen attack and the corresponding strength degradation is reported for silicon carbide, silicon nitride, alumina, magnesia, and mullite.

Material and Device Stability in Perovskite Solar Cells.

PubMed

Kim, Hui-Seon; Seo, Ja-Young; Park, Nam-Gyu

2016-09-22

Organic-inorganic halide perovskite solar cells have attracted great attention because of their superb efficiency reaching 22 % and low-cost, facile fabrication processing. Nevertheless, stability issues in perovskite solar cells seem to block further advancements toward commercialization. Thus, device stability is one of the important topics in perovskite solar cell research. In the beginning, the poor moisture resistivity of the perovskite layer was considered as a main problem that hindered further development of perovskite solar cells, which encouraged engineering of the perovskite or protection of the perovskite by a buffer layer. Soon after, other parameters affecting long-term stability were sequentially found and various attempts have been made to enhance intrinsic and extrinsic stability. Here we review the recent progresses addressing stability issues in perovskite solar cells. In this report, we investigated factors affecting stability from material and device points of view. To gain a better understanding of the stability of the bulk perovskite material, decomposition mechanisms were investigated in relation to moisture, photons, and heat. Stability of full device should also be carefully examined because its stability is dependent not only on bulk perovskite but also on the interfaces and selective contacts. In addition, ion migration and current-voltage hysteresis were found to be closely related to stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

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

Pierce, Eric M.; Mattigod, Shas V.; Westsik, Joseph H.

2010-01-30

Pacific Northwest National Laboratory has initiated a waste form testing program to support the long-term durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidificationmore » treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010.« less

Aqueous synthesis of near-infrared highly fluorescent platinum nanoclusters

NASA Astrophysics Data System (ADS)

García Fernández, Jenifer; Trapiella-Alfonso, Laura; Costa-Fernández, José M.; Pereiro, Rosario; Sanz-Medel, Alfredo

2015-05-01

A one-step synthesis of near infrared fluorescent platinum nanoclusters (PtNCs) in aqueous medium is described. The proposed optimized procedure for PtNC synthesis is rather simple, fast and it is based on the direct metal reduction with NaBH4. Bidentated thiol ligands (lipoic acid) were selected as nanoclusters stabilizers in water media. The structural characterization revealed attractive features of the PtNCs, including small size, high water solubility, near-infrared luminescence centered at 680 nm, long-term stability and the highest quantum yield in water reported so far (47%) for PtNCs. Moreover, their stability in different pH media and an ionic strength of 0.2 M NaCl was studied and no significant changes in fluorescence emission were detected. In brief, they offer a new type of fluorescent noble metal nanoprobe with a great potential to be applied in several fields, including biolabeling and imaging experiments.

Application of Millisecond Pulsar Timing to the Long-Term Stability of Clock Ensembles

NASA Technical Reports Server (NTRS)

Foster, Roger S.; Matsakis, Demetrios N.

1996-01-01

We review the application of millisecond pulsars to define a precise long-term standard and positional reference system in a nearly inertial reference frame. We quantify the current timing precision of the best millisecond pulsars and define the required precise time and time interval (PTTI) accuracy and stability to enable time transfer via pulsars. Pulsars may prove useful as independent standards to examine decade-long timing stability and provide an independent natural system within which to calibrate any new, perhaps vastly improved atomic time scale. Since pulsar stability appears to be related to the lifetime of the pulsar, the new millisecond pulsar J173+0747 is projected to have a 100-day accuracy equivalent to a single HP5071 cesium standard. Over the last five years, dozens of new millisecond pulsars have been discovered. A few of the new millisecond pulsars may have even better timing properties.

Effectiveness of Career Counseling: A One-Year Follow-Up

ERIC Educational Resources Information Center

Perdrix, Sophie; Stauffer, Sarah; Masdonati, Jonas; Massoudi, Koorosh; Rossier, Jerome

2012-01-01

The short-term effectiveness of career counseling is well supported in the literature. However, the long-term impact is often overlooked. This study quantitatively investigated the long-term stability of the positive effects gained through the career counseling process and qualitatively observed participants' levels of career project…

Optical frequency locked loop for long-term stabilization of broad-line DFB laser frequency difference

NASA Astrophysics Data System (ADS)

Lipka, Michał; Parniak, Michał; Wasilewski, Wojciech

2017-09-01

We present an experimental realization of the optical frequency locked loop applied to long-term frequency difference stabilization of broad-line DFB lasers along with a new independent method to characterize relative phase fluctuations of two lasers. The presented design is based on a fast photodiode matched with an integrated phase-frequency detector chip. The locking setup is digitally tunable in real time, insensitive to environmental perturbations and compatible with commercially available laser current control modules. We present a simple model and a quick method to optimize the loop for a given hardware relying exclusively on simple measurements in time domain. Step response of the system as well as phase characteristics closely agree with the theoretical model. Finally, frequency stabilization for offsets within 4-15 GHz working range achieving <0.1 Hz long-term stability of the beat note frequency for 500 s averaging time period is demonstrated. For these measurements we employ an I/Q mixer that allows us to precisely and independently measure the full phase trace of the beat note signal.

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

Lill, R.; Sereno, N.; Yang, B.

The Advanced Photon Source (APS) is currently in the preliminary design phase for the multi-bend achromat (MBA) lattice upgrade. Beam stability is critical for the MBA and will require long term drift defined as beam mo-tion over a seven-day timescale to be no more than 1 mi-cron at the insertion device locations and beam angle change no more than 0.25 micro-radian. Mechanical stabil-ity of beam position monitor (BPM) pickup electrodes mounted on insertion device vacuum chambers place a fun-damental limitation on long-term beam stability for inser-tion device beamlines. We present the design and imple-mentation of prototype mechanical motion system (MMS)more » instrumentation for quantifying this type of motion specif-ically in the APS accelerator tunnel and experiment hall floor under normal operating conditions. The MMS pres-ently provides critical position information on the vacuum chamber and BPM support systems. Initial results of the R&D prototype systems have demonstrated that the cham-ber movements far exceed the long-term drift tolerance specified for the APS Upgrade MBA storage ring.« less

Long-Term Stability of the SGA-WZ Strapdown Airborne Gravimeter

PubMed Central

Cai, Shaokun; Zhang, Kaidong; Wu, Meiping; Huang, Yangming

2012-01-01

Accelerometers are one of the most important sensors in a strapdown airborne gravimeter. The accelerometer's drift determines the long-term accuracy of the strapdown inertial navigation system (SINS), which is the primary and most critical component of the strapdown airborne gravimeter. A long-term stability test lasting 104 days was conducted to determine the characteristics of the strapdown airborne gravimeter's long-term drift. This stability test was based on the first set of strapdown airborne gravimeters built in China, the SGA-WZ. The test results reveal a quadratic drift in the strapdown airborne gravimeter data. A drift model was developed using the static data in the two end sections, and then this model was used to correct the test data. After compensating for the drift, the drift effect improved from 70 mGal to 3.46 mGal with a standard deviation of 0.63 mGal. The quadratic curve better reflects the drift's real characteristics. In comparison with other methodologies, modelling the drift as a quadratic curve was shown to be more appropriate. Furthermore, this method allows the drift to be adjusted throughout the course of the entire campaign. PMID:23112647

Depletion of Serotonin Selectively Impairs Short-Term Memory without Affecting Long-Term Memory in Odor Learning in the Terrestrial Slug "Limax Valentianus"

ERIC Educational Resources Information Center

Santa, Tomofumi; Kirino, Yutaka; Watanabe, Satoshi; Shirahata, Takaaki; Tsunoda, Makoto

2006-01-01

The terrestrial slug "Limax" is able to acquire short-term and long-term memories during aversive odor-taste associative learning. We investigated the effect of the selective serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) on memory. Behavioral studies indicated that 5,7-DHT impaired short-term memory but not long-term memory. HPLC…

Astrophysics and Cosmology: International Partnerships

NASA Astrophysics Data System (ADS)

Blandford, Roger

2016-03-01

Most large projects in astrophysics and cosmology are international. This raises many challenges including: --Aligning the sequence of: proposal, planning, selection, funding, construction, deployment, operation, data mining in different countries --Managing to minimize cost growth through reconciling different practices --Communicating at all levels to ensure a successful outcome --Stabilizing long term career opportunities. There has been considerable progress in confronting these challenges. Lessons learned from past collaborations are influencing current facilities but much remains to be done if we are to optimize the scientific and public return on the expenditure of financial and human resources.

Spectrally narrow, long-term stable optical frequency reference based on a Eu3+:Y2SiO5 crystal at cryogenic temperature.

PubMed

Chen, Qun-Feng; Troshyn, Andrei; Ernsting, Ingo; Kayser, Steffen; Vasilyev, Sergey; Nevsky, Alexander; Schiller, Stephan

2011-11-25

Using an ultrastable continuous-wave laser at 580 nm we performed spectral hole burning of Eu(3+):Y(2)SiO(5) at a very high spectral resolution. The essential parameters determining the usefulness as a macroscopic frequency reference, linewidth, temperature sensitivity, and long-term stability, were characterized using a H-maser stabilized frequency comb. Spectral holes with a linewidth as low as 6 kHz were observed and the upper limit of the drift of the hole frequency was determined to be 5±3 mHz/s. We discuss the necessary requirements for achieving ultrahigh stability in laser frequency stabilization to these spectral holes.

Explaining Variance in Long-Term Recall in 3- and 4-Year-Old Children: The Importance of Post-Encoding Processes

ERIC Educational Resources Information Center

Bauer, Patricia J.; Larkina, Marina; Doydum, Ayzit O.

2012-01-01

Long-term recall is influenced by what originally was encoded as well as by the efficacy of retrieval processes. The possible explanatory role of post-encoding processes by which initially labile memory traces are stabilized and integrated into long-term memory (i.e., consolidated) has received relatively less research attention. In the current…

Stabilization of dynamics of oscillatory systems by nonautonomous perturbation.

PubMed

Lucas, Maxime; Newman, Julian; Stefanovska, Aneta

2018-04-01

Synchronization and stability under periodic oscillatory driving are well understood, but little is known about the effects of aperiodic driving, despite its abundance in nature. Here, we consider oscillators subject to driving with slowly varying frequency, and investigate both short-term and long-term stability properties. For a phase oscillator, we find that, counterintuitively, such variation is guaranteed to enlarge the Arnold tongue in parameter space. Using analytical and numerical methods that provide information on time-variable dynamical properties, we find that the growth of the Arnold tongue is specifically due to the growth of a region of intermittent synchronization where trajectories alternate between short-term stability and short-term neutral stability, giving rise to stability on average. We also present examples of higher-dimensional nonlinear oscillators where a similar stabilization phenomenon is numerically observed. Our findings help support the case that in general, deterministic nonautonomous perturbation is a very good candidate for stabilizing complex dynamics.

Stabilization of dynamics of oscillatory systems by nonautonomous perturbation

NASA Astrophysics Data System (ADS)

Lucas, Maxime; Newman, Julian; Stefanovska, Aneta

2018-04-01

Synchronization and stability under periodic oscillatory driving are well understood, but little is known about the effects of aperiodic driving, despite its abundance in nature. Here, we consider oscillators subject to driving with slowly varying frequency, and investigate both short-term and long-term stability properties. For a phase oscillator, we find that, counterintuitively, such variation is guaranteed to enlarge the Arnold tongue in parameter space. Using analytical and numerical methods that provide information on time-variable dynamical properties, we find that the growth of the Arnold tongue is specifically due to the growth of a region of intermittent synchronization where trajectories alternate between short-term stability and short-term neutral stability, giving rise to stability on average. We also present examples of higher-dimensional nonlinear oscillators where a similar stabilization phenomenon is numerically observed. Our findings help support the case that in general, deterministic nonautonomous perturbation is a very good candidate for stabilizing complex dynamics.

Long term stability of Oligo (dT) 25 magnetic beads for the expression analysis of Euglena gracilis for long term space projects.

PubMed

Becker, Ina; Strauch, Sebastian M; Hauslage, Jens; Lebert, Michael

2017-05-01

The unicellular freshwater flagellate Euglena gracilis has a highly developed sensory system. The cells use different stimuli such as light and gravity to orient themselves in the surrounding medium to find areas for optimal growth. Due to the ability to produce oxygen and consume carbon dioxide, Euglena is a suitable candidate for life support systems. Participation in a long-term space experiment would allow for the analysis of changes and adaptations to the new environment, and this could bring new insights into the mechanism of perception of gravity and the associated signal transduction chain. For a molecular analysis of transcription patterns, an automated system is necessary, capable of performing all steps from taking a sample, processing it and generating data. One of the developmental steps is to find long-term stable reagents and materials and test them for stability at higher-than-recommended temperature conditions during extended storage time. We investigated the usability of magnetic beads in an Euglena specific lysis buffer after addition of the RNA stabilizer Dithiothreitol over 360 days and the lysis buffer with the stabilizer alone over 455 days at the expected storage temperature of 19 °C. We can claim that the stability is not impaired at all after an incubation period of over one year. This might be an interesting result for researchers who have to work under non-standard lab conditions, as in biological or medicinal fieldwork. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Characterization of cementitiously stabilized subgrades for mechanistic-empirical pavement design

NASA Astrophysics Data System (ADS)

Solanki, Pranshoo

Pavements are vulnerable to subgrade layer performance because it acts as a foundation. Due to increase in the truck traffic, pavement engineers are challenged to build more strong and long-lasting pavements. To increase the load-bearing capacity of pavements, subgrade layer is often stabilized with cementitious additives. Thus, an overall characterization of stabilized subgrade layer is important for enhanced short- and long-term pavement performance. In this study, the effect of type and amount of additive on the short-term performance in terms of material properties recommended by the new Mechanistic-Empirical Pavement Design Guide (MEPDG) is examined. A total of four soils commonly encountered as subgrades in Oklahoma are utilized. Results show that the changes in the Mr, ME and UCS values stabilized specimens depend on the soil type and properties of additives. The long-term performance (or durability) of stabilized soil specimens is investigated by conducting freeze-thaw (F-T) cycling, vacuum saturation and tube suction tests on 7-day cured P-, K- and C-soil specimens stabilized with 6% lime, 10% CFA and 10% CKD. This study is motivated by the fact that during the service life of pavement stabilized layers are subjected to F-T cycles and moisture variations. It is found that that UCS value of all the stabilized specimens decreased with increase in the number of F-T cycles. A strong correlation was observed between UCS values retained after vacuum saturation and F-T cycles indicating that vacuum saturation could be used as a time-efficient and inexpensive method for evaluating durability of stabilized soils. In this study, short- and long-term observations from stabilization of sulfate bearing soil with locally available low (CFA), moderate (CKD) and high (lime) calcium-based stabilizers are determined to evaluate and compare the effect of additive type on the phenomenon of sulfate-induced heave. The impact of different factors on the development of the ettringite, responsible for sulfate-induced heaving, is also discussed. For Level 2 design of pavements, a total of four stress-based statistical models and two feed-forward-type artificial neural network (ANN) models, are evaluated for predicting resilient modulus of 28-day cured stabilized specimens. Specifically, one semi-log stress-based, three log-log stress-based, one Multi-Layer Perceptrons Network (MLPN), and one Radial Basis Function Network (RBFN) are developed. Overall, semi-log stress-based and MLPN neural network are found to show best acceptable performance for the present evaluation and validation datasets. Further, correlations are presented for stress-based models to correlate Mr with compacted specimen characteristics and soil/additive properties. Additionally, the effect of type of additive on indirect tensile and fatigue characteristics of selected stabilized P- and V-soil is evaluated. This study is based on the fact that stabilized layer is subjected to tensile stresses under wheel loading. Thus, the resilient modulus in tension (M rt), fatigue life and strength in tension (sigmat) or flexure (represented by modulus of rupture, MOR) becomes another important design parameter within the mechanistic framework. Cylindrical specimens are prepared, cured for 28 days and subjected to different stress sequences in indirect tension to study the Mrt. On the other hand, stabilized beam specimens are compacted using a Linear Kneading Compactor and subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. It is found that all three additives improved the Mrt, sigmat and MOR values; however, degree of improvement varied with the type of additive and soil. This study encompasses the differences in the design of semi-rigid pavements developed using AASHTO 1993 and AASHTO 2002 MEPDG methodologies. Further, the design curves for fatigue performance prediction of stabilized layers are developed for different stabilized pavement sections. Knowledge gained from the parametric analysis of different sections using AASHTO 1993 and MEPDG is expected to be useful to pavement designers and others in implementation of the new MEPDG for future pavement design. (Abstract shortened by UMI.)

Material selection for a constructed wetroof receiving pre-treated high strength domestic wastewater.

PubMed

Zapater-Pereyra, M; van Dien, F; van Bruggen, J J A; Lens, P N L

2013-01-01

A constructed wetroof (CWR) is defined in this study as the combination of a green roof and a constructed wetland: a shallow wastewater treatment system placed on the roof of a building. The foremost challenge of such CWRs, and the main aim of this investigation, is the selection of an appropriate matrix capable of assuring the required hydraulic retention time, the long-term stability and the roof load-bearing capacity. Six substrata were subjected to water dynamics and destructive tests in two testing-tables. Among all the materials tested, the substratum configuration composed of sand, light expanded clay aggregates, biodegradable polylactic acid beads together with stabilization plates and a turf mat is capable of retaining the water for approximately 3.8 days and of providing stability (stabilization plates) and an immediate protection (turf mat) to the system. Based on those results, a full-scale CWR was built, which did not show any physical deterioration after 1 year of operation. Preliminary wastewater treatment results on the full-scale CWR suggest that it can highly remove main wastewater pollutants (e.g. chemical oxygen demand, PO4(3-)-P and NH4(+)-N). The results of these tests and practical design considerations of the CWR are discussed in this paper.

Biomechanical Concepts for Fracture Fixation

PubMed Central

Bottlang, Michael; Schemitsch, Christine E.; Nauth, Aaron; Routt, Milton; Egol, Kenneth; Cook, Gillian E.; Schemitsch, Emil H.

2015-01-01

Application of the correct fixation construct is critical for fracture healing and long-term stability; however, it is a complex issue with numerous significant factors. This review describes a number of common fracture types, and evaluates their currently available fracture fixation constructs. In the setting of complex elbow instability, stable fixation or radial head replacement with an appropriately sized implant in conjunction with ligamentous repair is required to restore stability. For unstable sacral fractures, “standard” iliosacral screw fixation is not sufficient for fractures with vertical or multiplanar instabilities. Periprosthetic femur fractures, in particular Vancouver B1 fractures, have increased stability when using 90/90 fixation versus a single locking plate. Far Cortical Locking combines the concept of dynamization with locked plating in order to achieve superior healing of a distal femur fracture. Finally, there is no ideal construct for syndesmotic fracture stabilization; however, these fractures should be fixed using a device that allows for sufficient motion in the syndesmosis. In general, orthopaedic surgeons should select a fracture fixation construct that restores stability and promotes healing at the fracture site, while reducing the potential for fixation failure. PMID:26584263

Long-term stability of crystal-stabilized water-in-oil emulsions.

PubMed

Ghosh, Supratim; Pradhan, Mamata; Patel, Tejas; Haj-Shafiei, Samira; Rousseau, Dérick

2015-12-15

The impact of cooling rate and mixing on the long-term kinetic stability of wax-stabilized water-in-oil emulsions was investigated. Four cooling/mixing protocols were investigated: cooling from 45°C to either 25°C or 4°C with/without stirring and two cooling rates - slow (1°C/min) and fast (5°C/min). The sedimentation behaviour of the emulsions was significantly affected by cooling protocol. Stirring was critical to the stability of all emulsions, with statically-cooled (no stirring) emulsions suffering from extensive aqueous phase separation. Emulsions stirred while cooling showed sedimentation of a waxy emulsion layer leaving a clear oil layer at the top, with a smaller separation and droplet size distribution at 4°C compared to 25°C, indicating the importance of the amount of crystallized wax on emulsion stability. Light microscopy revealed that crystallized wax appeared both on the droplet surface and in the continuous phase, suggesting that stirring ensured dispersibility of the water droplets during cooling as the wax was crystallizing. Wax crystallization on the droplet surface provided stability against droplet coalescence while continuous phase wax crystals minimized inter-droplet collisions. The key novel aspect of this research is in the simplicity to tailor the spatial distribution of wax crystals, i.e., either at the droplet surface or in the continuous phase via use of a surfactant and judicious stirring and/or cooling. Knowledge gained from this research can be applied to develop strategies for long-term storage stability of crystal-stabilized W/O emulsions. Copyright © 2015 Elsevier Inc. All rights reserved.

On the long-term stability of calibration standards in different matrices.

PubMed

Kandić, A; Vukanac, I; Djurašević, M; Novković, D; Šešlak, B; Milošević, Z

2012-09-01

In order to assure Quality Control in accordance with ISO/IEC 17025, it was important, from metrological point of view, to examine the long-term stability of calibration standards previously prepared. Comprehensive reconsideration on efficiency curves with respect to the ageing of calibration standards is presented in this paper. The calibration standards were re-used after a period of 5 years and analysis of the results showed discrepancies in efficiency values. Copyright © 2012 Elsevier Ltd. All rights reserved.

Polymer Latex Stability Modification by Exposure to Hydrophobic Solvents.

PubMed

de Oliveira Cardoso A; Galembeck

1998-08-01

The stability of latex particles toward coagulation in the presence of salt is modified by swelling the latex with toluene and chloroform vapors. Short-term stability was determined by turbidimetric titrations, and the long-term stability was evaluated by adding latex and salt solutions, allowing the mixture to age for 24 or 48 h and determining the characteristics of the supernatant and of the sediment. Nine different latexes were examined, with variable results: in some cases, both apolar solvents stabilize the latex; in other cases, increased stability is induced by only one of the solvents, either toluene or chloroform. There is also coherence, but not a strict correlation, between the solvent effects on short- and long-term stability. For instance, in the case of a core-and-shell styrene-butyl methacrylate latex, chloroform has a small stabilizing effect in the titration experiment, but it prevents the formation of a coagulated latex sediment even 48 h after mixing latex and salt. Two hypotheses are discussed to account for these observations: (i) swelling solvents decrease the particles ability to dissipate the collision kinetic energy, so that particles collide but without joining each other; (ii) the solvents induce the release of trapped charged groups from the particle interior to the interface, enhancing the usual (electrostatic, steric, hydration) stability factors. Copyright 1998 Academic Press.

The stability of liquid-filled matrix ionization chamber electronic portal imaging devices for dosimetry purposes.

PubMed

Louwe, R J W; Tielenburg, R; van Ingen, K M; Mijnheer, B J; van Herk, M B

2004-04-01

This study was performed to determine the stability of liquid-filled matrix ionization chamber (LiFi-type) electronic portal imaging devices (EPID) for dosimetric purposes. The short- and long-term stability of the response was investigated, as well as the importance of factors influencing the response (e.g., temperature fluctuations, radiation damage, and the performance of the electronic hardware). It was shown that testing the performance of the electronic hardware as well as the short-term stability of the imagers may reveal the cause of a poor long-term stability of the imager response. In addition, the short-term stability was measured to verify the validity of the fitted dose-response curve immediately after beam startup. The long-term stability of these imagers could be considerably improved by correcting for room temperature fluctuations and gradual changes in response due to radiation damage. As a result, the reproducibility was better than 1% (1 SD) over a period of two years. The results of this study were used to formulate recommendations for a quality control program for portal dosimetry. The effect of such a program was assessed by comparing the results of portal dosimetry and in vivo dosimetry using diodes during the treatment of 31 prostate patients. The improvement of the results for portal dosimetry was consistent with the deviations observed with the reproducibility tests in that particular period. After a correction for the variation in response of the imager, the average difference between the measured and prescribed dose during the treatment of prostate patients was -0.7%+/-1.5% (1 SD), and -0.6%+/-1.1% (1 SD) for EPID and diode in vivo dosimetry, respectively. It can be concluded that a high stability of the response can be achieved for this type of EPID by applying a rigorous quality control program.

Clinical review: Long-term noninvasive ventilation

PubMed Central

Robert, Dominique; Argaud, Laurent

2007-01-01

Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected to improve patient outcomes, reduce ICU admission, enhance patient comfort, and increase the efficiency of health care resource utilization. Current literature indicates that noninvasive ventilation improves and stabilizes the clinical course of many patients with chronic ventilatory failure. Noninvasive ventilation also permits long-term mechanical ventilation to be an acceptable option for patients who otherwise would not have been treated if tracheostomy were the only alternative. Nevertheless, these results appear to be better in patients with neuromuscular/-parietal disorders than in chronic obstructive pulmonary disease. This clinical review will address the use of noninvasive ventilation (not including continuous positive airway pressure) mainly in diseases responsible for chronic hypoventilation (that is, restrictive disorders, including neuromuscular disease and lung disease) and incidentally in others such as obstructive sleep apnea or problems of central drive. PMID:17419882

Monitoring of malolactic fermentation in wine using an electrochemical bienzymatic biosensor for L-lactate with long term stability.

PubMed

Giménez-Gómez, Pablo; Gutiérrez-Capitán, Manuel; Capdevila, Fina; Puig-Pujol, Anna; Fernández-Sánchez, César; Jiménez-Jorquera, Cecilia

2016-01-28

L-lactic acid is monitored during malolactic fermentation process of wine and its evolution is strongly related with the quality of the final product. The analysis of L-lactic acid is carried out off-line in a laboratory. Therefore, there is a clear demand for analytical tools that enabled real-time monitoring of this process in field and biosensors have positioned as a feasible alternative in this regard. The development of an amperometric biosensor for L-lactate determination showing long-term stability is reported in this work. The biosensor architecture includes a thin-film gold electrochemical transducer selectively modified with an enzymatic membrane, based on a three-dimensional matrix of polypyrrole (PPy) entrapping lactate oxidase (LOX) and horseradish peroxidase (HRP) enzymes. The experimental conditions of the biosensor fabrication regarding the pyrrole polymerization and the enzymes entrapment are optimized. The biosensor response to L-lactate is linear in a concentration range of 1 × 10(-6)-1 × 10(-4) M, with a detection limit of 5.2 × 10(-7) M and a sensitivity of - (13500 ± 600) μA M(-1) cm(-2). The biosensor shows an excellent working stability, retaining more than 90% of its original sensitivity after 40 days. This is the determining factor that allowed for the application of this biosensor to monitor the malolactic fermentation of three red wines, showing a good agreement with the standard colorimetric method. Copyright © 2015 Elsevier B.V. All rights reserved.

Humidity-corrected Arrhenius equation: The reference condition approach.

PubMed

Naveršnik, Klemen; Jurečič, Rok

2016-03-16

Accelerated and stress stability data is often used to predict shelf life of pharmaceuticals. Temperature, combined with humidity accelerates chemical decomposition and the Arrhenius equation is used to extrapolate accelerated stability results to long-term stability. Statistical estimation of the humidity-corrected Arrhenius equation is not straightforward due to its non-linearity. A two stage nonlinear fitting approach is used in practice, followed by a prediction stage. We developed a single-stage statistical procedure, called the reference condition approach, which has better statistical properties (less collinearity, direct estimation of uncertainty, narrower prediction interval) and is significantly easier to use, compared to the existing approaches. Our statistical model was populated with data from a 35-day stress stability study on a laboratory batch of vitamin tablets and required mere 30 laboratory assay determinations. The stability prediction agreed well with the actual 24-month long term stability of the product. The approach has high potential to assist product formulation, specification setting and stability statements. Copyright © 2016 Elsevier B.V. All rights reserved.

3D printed cellular solid outperforms traditional stochastic foam in long-term mechanical response

DOE PAGES

Maiti, A.; Small, W.; Lewicki, J.; ...

2016-04-27

3D printing of polymeric foams by direct-ink-write is a recent technological breakthrough that enables the creation of versatile compressible solids with programmable microstructure, customizable shapes, and tunable mechanical response including negative elastic modulus. However, in many applications the success of these 3D printed materials as a viable replacement for traditional stochastic foams critically depends on their mechanical performance and micro-architectural stability while deployed under long-term mechanical strain. To predict the long-term performance of the two types of foams we employed multi-year-long accelerated aging studies under compressive strain followed by a time-temperature-superposition analysis using a minimum-arc-length-based algorithm. The resulting master curvesmore » predict superior long-term performance of the 3D printed foam in terms of two different metrics, i.e., compression set and load retention. To gain deeper understanding, we imaged the microstructure of both foams using X-ray computed tomography, and performed finite-element analysis of the mechanical response within these microstructures. As a result, this indicates a wider stress variation in the stochastic foam with points of more extreme local stress as compared to the 3D printed material, which might explain the latter’s improved long-term stability and mechanical performance.« less

3D printed cellular solid outperforms traditional stochastic foam in long-term mechanical response

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

Maiti, A.; Small, W.; Lewicki, J.

3D printing of polymeric foams by direct-ink-write is a recent technological breakthrough that enables the creation of versatile compressible solids with programmable microstructure, customizable shapes, and tunable mechanical response including negative elastic modulus. However, in many applications the success of these 3D printed materials as a viable replacement for traditional stochastic foams critically depends on their mechanical performance and micro-architectural stability while deployed under long-term mechanical strain. To predict the long-term performance of the two types of foams we employed multi-year-long accelerated aging studies under compressive strain followed by a time-temperature-superposition analysis using a minimum-arc-length-based algorithm. The resulting master curvesmore » predict superior long-term performance of the 3D printed foam in terms of two different metrics, i.e., compression set and load retention. To gain deeper understanding, we imaged the microstructure of both foams using X-ray computed tomography, and performed finite-element analysis of the mechanical response within these microstructures. As a result, this indicates a wider stress variation in the stochastic foam with points of more extreme local stress as compared to the 3D printed material, which might explain the latter’s improved long-term stability and mechanical performance.« less

3D printed cellular solid outperforms traditional stochastic foam in long-term mechanical response

NASA Astrophysics Data System (ADS)

Maiti, A.; Small, W.; Lewicki, J. P.; Weisgraber, T. H.; Duoss, E. B.; Chinn, S. C.; Pearson, M. A.; Spadaccini, C. M.; Maxwell, R. S.; Wilson, T. S.

2016-04-01

3D printing of polymeric foams by direct-ink-write is a recent technological breakthrough that enables the creation of versatile compressible solids with programmable microstructure, customizable shapes, and tunable mechanical response including negative elastic modulus. However, in many applications the success of these 3D printed materials as a viable replacement for traditional stochastic foams critically depends on their mechanical performance and micro-architectural stability while deployed under long-term mechanical strain. To predict the long-term performance of the two types of foams we employed multi-year-long accelerated aging studies under compressive strain followed by a time-temperature-superposition analysis using a minimum-arc-length-based algorithm. The resulting master curves predict superior long-term performance of the 3D printed foam in terms of two different metrics, i.e., compression set and load retention. To gain deeper understanding, we imaged the microstructure of both foams using X-ray computed tomography, and performed finite-element analysis of the mechanical response within these microstructures. This indicates a wider stress variation in the stochastic foam with points of more extreme local stress as compared to the 3D printed material, which might explain the latter’s improved long-term stability and mechanical performance.

3D printed cellular solid outperforms traditional stochastic foam in long-term mechanical response

PubMed Central

Maiti, A.; Small, W.; Lewicki, J. P.; Weisgraber, T. H.; Duoss, E. B.; Chinn, S. C.; Pearson, M. A.; Spadaccini, C. M.; Maxwell, R. S.; Wilson, T. S.

2016-01-01

3D printing of polymeric foams by direct-ink-write is a recent technological breakthrough that enables the creation of versatile compressible solids with programmable microstructure, customizable shapes, and tunable mechanical response including negative elastic modulus. However, in many applications the success of these 3D printed materials as a viable replacement for traditional stochastic foams critically depends on their mechanical performance and micro-architectural stability while deployed under long-term mechanical strain. To predict the long-term performance of the two types of foams we employed multi-year-long accelerated aging studies under compressive strain followed by a time-temperature-superposition analysis using a minimum-arc-length-based algorithm. The resulting master curves predict superior long-term performance of the 3D printed foam in terms of two different metrics, i.e., compression set and load retention. To gain deeper understanding, we imaged the microstructure of both foams using X-ray computed tomography, and performed finite-element analysis of the mechanical response within these microstructures. This indicates a wider stress variation in the stochastic foam with points of more extreme local stress as compared to the 3D printed material, which might explain the latter’s improved long-term stability and mechanical performance. PMID:27117858

Anion selective membrane. [ion exchange resins and ion exchange membrane electrolytes for electrolytic cells

NASA Technical Reports Server (NTRS)

Alexander, S. S.; Geoffroy, R. R.; Hodgdon, R. B.

1975-01-01

Experimental anion permselective membranes were prepared and tested for their suitability as cell separators in a chemical redox power storage system being developed at NASA-Lewis Research Center. The goals of long-term (1000 hr) oxidative and thermal stability at 80 C in FeCl3 and CrCl3 electrolytes were met by most of the weak base and strong base amino exchange groups considered in the program. Good stability is exhibited by several of the membrane substrate resins. These are 'styrene' divinylbenzene copolymer and PVC film. At least four membrane systems produce strong flexible films with electrochemical properties (resistivity, cation transfer) superior to those of the 103QZL, the most promising commercial membrane. The physical and chemical properties of the resins are listed.

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.

Effects of Sustained Abstinence Among Treated Substance-Abusing Homeless Persons on Housing and Employment

PubMed Central

Schumacher, Joseph E.; Wallace, Dennis; Vuchinich, Rudy; Mennemeyer, Stephen T.; Kertesz, Stefan G.

2010-01-01

Objectives. We examined whether cocaine-dependent homeless persons had stable housing and were employed 6, 12, and 18 months after they entered a randomized controlled trial comparing 2 treatments. Methods. One group (n = 103) received abstinence-contingent housing, vocational training, and work; another group (n = 103) received the same intervention plus cognitive behavioral day treatment. We examined baseline and early treatment variables for association with long-term housing and employment. Results. Although the enhanced-treatment group achieved better abstinence rates, the groups did not differ in long-term housing and employment stability. However, consecutive weeks of abstinence during treatment (and to a lesser extent, older age and male gender) predicted long-term housing and employment stability after adjustment for baseline differences in employment, housing, and treatment. Conclusions. Our data showed a relationship of abstinence with housing stability. Contrasting these results with the increasingly popular Housing First interventions reveals important gaps in our knowledge to be addressed in future research. PMID:19833998

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.

Epoxide-functionalization of polyethyleneimine for synthesis of stable carbon dioxide adsorbent in temperature swing adsorption

PubMed Central

Choi, Woosung; Min, Kyungmin; Kim, Chaehoon; Ko, Young Soo; Jeon, Jae Wan; Seo, Hwimin; Park, Yong-Ki; Choi, Minkee

2016-01-01

Amine-containing adsorbents have been extensively investigated for post-combustion carbon dioxide capture due to their ability to chemisorb low-concentration carbon dioxide from a wet flue gas. However, earlier studies have focused primarily on the carbon dioxide uptake of adsorbents, and have not demonstrated effective adsorbent regeneration and long-term stability under such conditions. Here, we report the versatile and scalable synthesis of a functionalized-polyethyleneimine (PEI)/silica adsorbent which simultaneously exhibits a large working capacity (2.2 mmol g−1) and long-term stability in a practical temperature swing adsorption process (regeneration under 100% carbon dioxide at 120 °C), enabling the separation of concentrated carbon dioxide. We demonstrate that the functionalization of PEI with 1,2-epoxybutane reduces the heat of adsorption and facilitates carbon dioxide desorption (>99%) during regeneration compared with unmodified PEI (76%). Moreover, the functionalization significantly improves long-term adsorbent stability over repeated temperature swing adsorption cycles due to the suppression of urea formation and oxidative amine degradation. PMID:27572662

Superior long-term stability of a glucose biosensor based on inserted barrel plating gold electrodes.

PubMed

Hsu, Cheng-Teng; Hsiao, Hung-Chan; Fang, Mei-Yen; Zen, Jyh-Myng

2009-10-15

Disposable one shot usage blood glucose strips are routinely used in the diagnosis and management of diabetes mellitus and their performance can vary greatly. In this paper we critically evaluated the long-term stability of glucose strips made of barrel plating gold electrodes. Compared to other glucose biosensing platforms of vapor deposited palladium and screen printed carbon electrodes, the proposed glucose biosensor was found to show the best stability among the three biosensing platforms in thermal acceleration experiments at 40 degrees C for 6 months with an average bias of 3.4% at glucose concentrations of 5-20 mM. The precision test of this barrel plating gold glucose biosensor also showed the best performance (coefficients of variation in the range of 1.4-2.4%) in thermal acceleration experiments at 40 degrees C, 50 degrees C and 70 degrees C for 27 days. Error grid analysis revealed that all measurements fell in zone A and zone B. Regression analysis showed no significant difference between the proposed biosensor and the reference method at 99% confidence level. The amperometric glucose biosensor fabricated by inserting two barrel plating gold electrodes onto an injection-molding plastic base followed by immobilizing with a bio-reagent layer and membrane was very impressive with a long-term stability up to 2.5 years at 25 degrees C. Overall, these results indicated that the glucose oxidase/barrel plating gold biosensing platform is ideal for long-term accurate glycemic control.

Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

2003-01-01

Advanced oxide thermal barrier coatings have been developed by incorporating multi-component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma-sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), electron energy-loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia- yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging from 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

1990-01-01

Advanced oxide thermal barrier coatings have been developed by incorporating multi- component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma- sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia-yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging fiom 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

Long-term Operation of an External Cavity Quantum Cascade Laser-based Trace-gas Sensor for Building Air Monitoring

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

Phillips, Mark C.; Craig, Ian M.

2013-11-03

We analyze the long-term performance and stability of a trace-gas sensor based on an external cavity quantum cascade laser using data collected over a one-year period in a building air monitoring application.

Production stability of active polysaccharides of Dendrobium huoshanense using long-term cultures of protocorm-like bodies.

PubMed

Zha, Xue-Qiang; Luo, Jian-Ping

2008-01-01

In this study, the production stability of active polysaccharides in protocorm-like bodies (PLBs) induced from the seedling segments of Dendrobium huoshanense C. Z. Tang et S. J. Cheng was investigated during long-term subculture. Subcultures were conducted once every 30 days. With an average inoculum of 39 g/L fresh PLBs, the increase in biomass ranged from 95.7 g/L to 103.9 g/L in fresh weight and 3.2 g/L to 3.4 g/L in dry weight during eighteen continuous subcultures while polysaccharide content in PLBs was from 0.8 mg/g Fw (mg polysaccharide per gram PLBs in fresh weight) to 1.0 mg/g Fw. In addition, polysaccharides from all cultures showed a similar potential of stimulating interferon gamma (IFN-gamma) release in the supernatant of splenocytes and tumor necrosis factor alpha (TNF-alpha) release in the supernatant of peritoneal macrophages. To elucidate the genetic basis of polysaccharide production stability in long-term subculture of PLBs, the genetic fingerprints by RAPD were further analyzed using plantlets from PLB development. Results showed that there is no evidence of genetic variation both within the plantlets from the different subcultures of PLBs and between long-term subcultures and the donor plants.

Simple surface engineering of polydimethylsiloxane with polydopamine for stabilized mesenchymal stem cell adhesion and multipotency

PubMed Central

Chuah, Yon Jin; Koh, Yi Ting; Lim, Kaiyang; Menon, Nishanth V.; Wu, Yingnan; Kang, Yuejun

2015-01-01

Polydimethylsiloxane (PDMS) has been extensively exploited to study stem cell physiology in the field of mechanobiology and microfluidic chips due to their transparency, low cost and ease of fabrication. However, its intrinsic high hydrophobicity renders a surface incompatible for prolonged cell adhesion and proliferation. Plasma-treated or protein-coated PDMS shows some improvement but these strategies are often short-lived with either cell aggregates formation or cell sheet dissociation. Recently, chemical functionalization of PDMS surfaces has proved to be able to stabilize long-term culture but the chemicals and procedures involved are not user- and eco-friendly. Herein, we aim to tailor greener and biocompatible PDMS surfaces by developing a one-step bio-inspired polydopamine coating strategy to stabilize long-term bone marrow stromal cell culture on PDMS substrates. Characterization of the polydopamine-coated PDMS surfaces has revealed changes in surface wettability and presence of hydroxyl and secondary amines as compared to uncoated surfaces. These changes in PDMS surface profile contribute to the stability in BMSCs adhesion, proliferation and multipotency. This simple methodology can significantly enhance the biocompatibility of PDMS-based microfluidic devices for long-term cell analysis or mechanobiological studies. PMID:26647719

Long term stability of nanowire nanoelectronics in physiological environments.

PubMed

Zhou, Wei; Dai, Xiaochuan; Fu, Tian-Ming; Xie, Chong; Liu, Jia; Lieber, Charles M

2014-03-12

Nanowire nanoelectronic devices have been exploited as highly sensitive subcellular resolution detectors for recording extracellular and intracellular signals from cells, as well as from natural and engineered/cyborg tissues, and in this capacity open many opportunities for fundamental biological research and biomedical applications. Here we demonstrate the capability to take full advantage of the attractive capabilities of nanowire nanoelectronic devices for long term physiological studies by passivating the nanowire elements with ultrathin metal oxide shells. Studies of Si and Si/aluminum oxide (Al2O3) core/shell nanowires in physiological solutions at 37 °C demonstrate long-term stability extending for at least 100 days in samples coated with 10 nm thick Al2O3 shells. In addition, investigations of nanowires configured as field-effect transistors (FETs) demonstrate that the Si/Al2O3 core/shell nanowire FETs exhibit good device performance for at least 4 months in physiological model solutions at 37 °C. The generality of this approach was also tested with in studies of Ge/Si and InAs nanowires, where Ge/Si/Al2O3 and InAs/Al2O3 core/shell materials exhibited stability for at least 100 days in physiological model solutions at 37 °C. In addition, investigations of hafnium oxide-Al2O3 nanolaminated shells indicate the potential to extend nanowire stability well beyond 1 year time scale in vivo. These studies demonstrate that straightforward core/shell nanowire nanoelectronic devices can exhibit the long term stability needed for a range of chronic in vivo studies in animals as well as powerful biomedical implants that could improve monitoring and treatment of disease.

Long Term Stability of Nanowire Nanoelectronics in Physiological Environments

PubMed Central

2015-01-01

Nanowire nanoelectronic devices have been exploited as highly sensitive subcellular resolution detectors for recording extracellular and intracellular signals from cells, as well as from natural and engineered/cyborg tissues, and in this capacity open many opportunities for fundamental biological research and biomedical applications. Here we demonstrate the capability to take full advantage of the attractive capabilities of nanowire nanoelectronic devices for long term physiological studies by passivating the nanowire elements with ultrathin metal oxide shells. Studies of Si and Si/aluminum oxide (Al2O3) core/shell nanowires in physiological solutions at 37 °C demonstrate long-term stability extending for at least 100 days in samples coated with 10 nm thick Al2O3 shells. In addition, investigations of nanowires configured as field-effect transistors (FETs) demonstrate that the Si/Al2O3 core/shell nanowire FETs exhibit good device performance for at least 4 months in physiological model solutions at 37 °C. The generality of this approach was also tested with in studies of Ge/Si and InAs nanowires, where Ge/Si/Al2O3 and InAs/Al2O3 core/shell materials exhibited stability for at least 100 days in physiological model solutions at 37 °C. In addition, investigations of hafnium oxide-Al2O3 nanolaminated shells indicate the potential to extend nanowire stability well beyond 1 year time scale in vivo. These studies demonstrate that straightforward core/shell nanowire nanoelectronic devices can exhibit the long term stability needed for a range of chronic in vivo studies in animals as well as powerful biomedical implants that could improve monitoring and treatment of disease. PMID:24479700

Optoelectronic oscillator with improved phase noise and frequency stability

NASA Astrophysics Data System (ADS)

Eliyahu, Danny; Sariri, Kouros; Taylor, Joseph; Maleki, Lute

2003-07-01

In this paper we report on recent improvements in phase noise and frequency stability of a 10 GHz opto-electronic oscillator. In our OEO loop, the high Q elements (the optical fiber and the narrow bandpass microwave filter) are thermally stabilized using resistive heaters and temperature controllers, keeping their temperature above ambient. The thermally stabilized free running OEO demonstrates a short-term frequency stability of 0.02 ppm (over several hours) and frequency vs. temperature slope of -0.1 ppm/°C (compared to -8.3 ppm/°C for non thermally stabilized OEO). We obtained an exceptional spectral purity with phase noise level of -143 dBc/Hz at 10 kHz of offset frequency. We also describe the multi-loop configuration that reduces dramatically the spurious level at offset frequencies related to the loop round trip harmonic frequency. The multi-loop configuration has stronger mode selectivity due to interference between signals having different cavity lengths. A drop of the spurious level below -90 dBc was demonstrated. The effect of the oscillator aging on the frequency stability was studied as well by recording the oscillator frequency (in a chamber) over several weeks. We observed reversal in aging direction with logarithmic behavior of A ln(B t+1)-C ln(D t+1), where t is the time and A, B, C, D are constants. Initially, in the first several days, the positive aging dominates. However, later the negative aging mechanism dominates. We have concluded that the long-term aging behavioral model is consistent with the experimental results.

Study of advanced fuel system concepts for commercial aircraft and engines

NASA Technical Reports Server (NTRS)

Versaw, E. F.; Brewer, G. D.; Byers, W. D.; Fogg, H. W.; Hanks, D. E.; Chirivella, J.

1983-01-01

The impact on a commercial transport aircraft of using fuels which have relaxed property limits relative to current commercial jet fuel was assessed. The methodology of the study is outlined, fuel properties are discussed, and the effect of the relaxation of fuel properties analyzed. Advanced fuel system component designs that permit the satisfactory use of fuel with the candidate relaxed properties in the subject aircraft are described. The two fuel properties considered in detail are freezing point and thermal stability. Three candidate fuel system concepts were selected and evaluated in terms of performance, cost, weight, safety, and maintainability. A fuel system that incorporates insulation and electrical heating elements on fuel tank lower surfaces was found to be most cost effective for the long term.

Functional Evidence for Memory Stabilization in Sensorimotor Adaptation: A 24-h Resting-State fMRI Study.

PubMed

Della-Maggiore, Valeria; Villalta, Jorge I; Kovacevic, Natasa; McIntosh, Anthony Randal

2017-03-01

Adaptation learning is crucial to maintain precise motor control in face of environmental perturbations. Although much progress has been made in understanding the psychophysics and neurophysiology of sensorimotor adaptation (SA), the time course of memory consolidation remains elusive. The lack of a reproducible gradient of memory resistance using protocols of retrograde interference has even led to the proposal that memories produced through SA do not consolidate. Here, we pursued an alternative approach using resting-state fMRI to track changes in functional connectivity (FC) induced by learning. Given that consolidation leads to long-term memory, we hypothesized that a change in FC that predicted long-term memory but not short-term memory would provide indirect evidence for memory stabilization. Six scans were acquired before, 15 min, 1, 3, 5.5, and 24 h after training on a center-out task under veridical or distorted visual feedback. The experimental group showed an increment in FC of a network including motor, premotor, posterior parietal cortex, cerebellum, and putamen that peaked at 5.5 h. Crucially, the strengthening of this network correlated positively with long-term retention but negatively with short-term retention. Our work provides evidence, suggesting that adaptation memories stabilize within a 6-h window, and points to different mechanisms subserving short- and long-term memory. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Alumina/polymer-coated nanocrystals with extremely high stability used as a color conversion material in LEDs

NASA Astrophysics Data System (ADS)

Woo, Ju Yeon; Lee, Jongsoo; Han, Chang-Soo

2013-12-01

The long-term stability of quantum dot (QD)-based devices under harsh environmental conditions has been a critical bottleneck to be resolved for commercial use. Here, we demonstrate an extremely stable QD/alumina/polymer hybrid structure by combining internal atomic layer deposition (ALD) infilling with polymer encapsulation. ALD infilling and polymer encapsulation of QDs synergistically prohibit the degradation of QDs in terms of optical, thermal and humid attacks. Our hybrid QD/alumina/polymer film structure showed no noticeable reduction in photoluminescence even in a commercial grade test (85% humidity at 85 ° C) over 28 days. In addition, we successfully fabricated a QD-based light-emitting device with excellent long-term stability by incorporating hybrid QD/alumina/polymer film as a color conversion material on light-emitting diode chips.

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

Jung, Haeryong; Lee, Eunyong; Jeong, YiYeong

Korea Radioactive-waste Management Corporation (KRMC) established in 2009 has started a new project to collect information on long-term stability of deep geological environments on the Korean Peninsula. The information has been built up in the integrated natural barrier database system available on web (www.deepgeodisposal.kr). The database system also includes socially and economically important information, such as land use, mining area, natural conservation area, population density, and industrial complex, because some of this information is used as exclusionary criteria during the site selection process for a deep geological repository for safe and secure containment and isolation of spent nuclear fuel andmore » other long-lived radioactive waste in Korea. Although the official site selection process has not been started yet in Korea, current integrated natural barrier database system and socio-economic database is believed that the database system will be effectively utilized to narrow down the number of sites where future investigation is most promising in the site selection process for a deep geological repository and to enhance public acceptance by providing readily-available relevant scientific information on deep geological environments in Korea. (authors)« less

A tripolar-electrode ionization gas sensor using a carbon nanotube cathode for NO detection

NASA Astrophysics Data System (ADS)

Song, Hui; Li, Kun; Li, Quanfu

2018-06-01

Nitric oxide accounts for more than 95% of the total NO X emission from power plants, which is a major air pollutant. Therefore, it is imperative to accurately detect NO for environmental protection. A tripolar-electrode ionization sensor with a carbon nanotube (CNT) cathode is proposed for NO detection. The non-self-sustaining discharge state and the tripolar-electrode configuration ensures a long nanotube life, which ensures a good stability and fast response of the sensor. Experimental results demonstrate that the tripolar-electrode ionization sensor with 120 µm separations has an intrinsic monotonously decreasing response to NO and exhibits a fast response time of 7 s and recovery time of 8 s. More consumption of the two metastable states N2(A3  ∑  u +) and N2(aʹ1  ∑  u +) of N2 with the increasing of NO concentration is responsible for this. The tripolar-electrode ionization sensor also shows excellent long-term stability of at least one month due to the long CNT life. In addition, the weak effect of SO2 introduction on NO response indicates a good selectivity of the sensor to NO.

Storage and stability of mineral-associated soil organic matter pools in genetic horizons of harvested coniferous forest soils

NASA Astrophysics Data System (ADS)

Gabriel, C. E.; Kellman, L. M.; Ziegler, S.

2016-12-01

Mineral soil organic matter (SOM) is associated with a suite of secondary minerals that can confer stability, resulting in the potential for long-term storage of carbon (C). Not all interactions impart the same level of stability, however; evidence is suggesting that SOM in certain mineral phases is dynamic and vulnerable to soil disturbance, such as forest harvesting. The objective of this research was to characterize SOM-mineral interactions in horizons of harvested soils of contrasting stand age. Sequential selective dissolutions representing increasingly stable SOM pools from soluble minerals (deionized water (DI)), non-crystalline (Na-pyrophosphate), poorly-crystalline minerals (HCl hydroxylamine), to crystalline secondary minerals (Na-dithionite HCl)) were carried out for Ae, Bf and BC horizons sampled from a young and mature forest site (35 and 110 years post-harvest) in Mooseland, Nova Scotia, Canada. Selective dissolution extracts were analyzed for dissolved organic carbon (DOC), its δ13C, Fe and Al. Initial isotopic analysis indicates that separate operational SOM pools were isolated: δ13C values of pyrophosphate-extracted non-crystalline (NC) phases were -27 to -28‰, similar to δ13C of bulk C and to plant-derived humic acids and fungal biomass, whereas the δ13C of DI extracts were more depleted in 13C (1-2 ‰). These SOM pools retained their isotopic signature through depth despite an enrichment in bulk SOM δ13C. NC dominated the C distribution for all horizons, followed by poorly crystalline (PC) minerals, and the C content of these two phases explained the variation in bulk C, while C in crystalline pools were similar for the two sites through depth. The mature site had twice as much C in the NC pool as the young site in the Bf horizons, supported by higher C/Fe+Al ratios, suggesting a change in loading following harvesting. Despite the destabilizing processes that occur with forest harvesting and evidence for the increased destabilization of NC and PC pools of SOM, those pools associated with crystalline OM remain stable, suggesting that the nature of mineral-SOM binding determines its stability and therefore its potential for long-term storage.

Frequency stabilization of an optically pumped far-infrared laser to the harmonic of a microwave synthesizer.

PubMed

Danylov, A A; Light, A R; Waldman, J; Erickson, N

2015-12-10

Measurements of the frequency stability of a far-infrared molecular laser have been made by mixing the harmonic of an ultrastable microwave source with a portion of the laser output signal in a terahertz (THz) Schottky diode balanced mixer. A 3 GHz difference-frequency signal was used in a frequency discriminator circuit to lock the laser to the microwave source. Comparisons of the short- and long-term laser frequency stability under free-running and locked conditions show a significant improvement with locking. Short-term frequency jitter was reduced by an order of magnitude, from approximately 40 to 4 kHz, and long-term drift was reduced by more than three orders of magnitude, from approximately 250 kHz to 80 Hz. The results, enabled by the efficient Schottky diode balanced mixer downconverter, demonstrate that ultrastable microwave-based frequency stabilization of THz optically pumped lasers (OPLs) will now be possible at frequencies extending well above 4.0 THz.

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.

Association of Amplitude and Stability of Circadian Rhythm, Sleep Quality, and Occupational Stress with Sickness Absence among a Gas Company Employees-A Cross Sectional Study from Iran.

PubMed

Zare, Rezvan; Choobineh, Alireza; Keshavarzi, Sareh

2017-09-01

The present study was carried out to assess the relationship between sickness absence and occupational stress, sleep quality, and amplitude and stability of circadian rhythm as well as to determine contributing factors of sickness absence. This cross sectional study was conducted on 400 randomly selected employees of an Iranian gas company. The data were collected using Pittsburgh sleep quality index, Karolinska sleepiness scale, circadian type inventory, and Osipow occupational stress questionnaires. The mean age and job tenure of the participants were 33.18 ± 5.64 years and 6.06 ± 4.99 years, respectively. Also, the participants had been absent from work on average 2.16 days a year. According to the results, 209 participants had no absences, 129 participants had short-term absences, and 62 participants had long-term absences. The results showed a significant relationship between short-term absenteeism and amplitude of circadian rhythm [odds ratio (OR) = 6.13], sleep quality (OR = 14.46), sleepiness (OR = 2.08), role boundary (OR = 6.45), and responsibility (OR = 5.23). Long-term absenteeism was also significantly associated with amplitude of circadian rhythm (OR = 2.42), sleep quality (OR = 21.56), sleepiness (OR = 6.44), role overload (OR = 4.84), role boundary (OR = 4.27), and responsibility (OR = 3.72). The results revealed that poor sleep quality, amplitude of circadian rhythm, and occupational stress were the contributing factors for sickness absence in the study population.

Leveraging Venture Capital and Commercial Business: Enhancing Stability Operations

DTIC Science & Technology

2011-03-24

Economic Stability Operations have emerged as a new element of United States national strategic power. The creation of jobs, through commercial...examine the key strategic factors influencing long-term economic stability following the withdrawal of combat forces. This paper provides a model for

Genetic architecture and the evolution of sex.

PubMed

Lohaus, Rolf; Burch, Christina L; Azevedo, Ricardo B R

2010-01-01

Theoretical investigations of the advantages of sex have tended to treat the genetic architecture of organisms as static and have not considered that genetic architecture might coevolve with reproductive mode. As a result, some potential advantages of sex may have been missed. Using a gene network model, we recently showed that recombination imposes selection for robustness to mutation and that negative epistasis can evolve as a by-product of this selection. These results motivated a detailed exploration of the mutational deterministic hypothesis, a hypothesis in which the advantage of sex depends critically on epistasis. We found that sexual populations do evolve higher mean fitness and lower genetic load than asexual populations at equilibrium, and, under moderate stabilizing selection and large population size, these equilibrium sexual populations resist invasion by asexuals. However, we found no evidence that these long- and short-term advantages to sex were explained by the negative epistasis that evolved in our experiments. The long-term advantage of sex was that sexual populations evolved a lower deleterious mutation rate, but this property was not sufficient to account for the ability of sexual populations to resist invasion by asexuals. The ability to resist asexual invasion was acquired simultaneously with an increase in recombinational robustness that minimized the cost of sex. These observations provide the first direct evidence that sexual reproduction does indeed select for conditions that favor its own maintenance. Furthermore, our results highlight the importance of considering a dynamic view of the genetic architecture to understand the evolution of sex and recombination.

[Long-term memory, neurogenesis and novelty signal].

PubMed

Sokolova, E N; Nezlina, N I

2003-01-01

In accordance with the advanced hypothesis the long-term memory is a collection of "gnostic units" selectively tuned to experienced events. The long-term memory is continuously supplemented by new neurons differentiated from stem cells during neurogenesis (particularly, in adults). The transformation of neuronal progenitors into event-selective gnostic units is accomplished with participation of hippocampal "novelty neurons" emphasizing information inputs to be stored in the long-term memory. The formation of the gnostic units is preceded by informational processes occurring in the ventral ("what?") and dorsal ("where?") systems. The formation of a new gnostic unit selectively tuned to a particular event is a result of combination of feature-detector excitation and novelty signal generated by hippocampal novelty neurons.

Long-term manure amendments reduced soil aggregate stability via redistribution of the glomalin-related soil protein in macroaggregates

PubMed Central

Xie, Hongtu; Li, Jianwei; Zhang, Bin; Wang, Lianfeng; Wang, Jingkuan; He, Hongbo; Zhang, Xudong

2015-01-01

Glomalin-related soil protein (GRSP) contributes to the formation and maintenance of soil aggregates, it is however remains unclear whether long-term intensive manure amendments alter soil aggregates stability and whether GRSP regulates these changes. Based on a three-decade long fertilization experiment in northeast China, this study examined the impact of long-term manure input on soil organic carbon (SOC), total and easily extractable GRSP (GRSPt and GRSPe) and their respective allocations in four soil aggregates (>2000 μm; 2000–250 μm; 250–53 μm; and <53 μm). The treatments include no fertilization (CK), low and high manure amendment (M1, M2), chemical nitrogen, phosphorus and potassium fertilizers (NPK), and combined manure and chemical fertilizers (NPKM1, NPKM2). Though SOC, GRSPe and GRSPt in soil and SOC in each aggregate generally increased with increasing manure input, GRSPt and GRSPe in each aggregate showed varying changes with manure input. Both GRSP in macroaggregates (2000–250 μm) were significantly higher under low manure input, a pattern consistent with changes in soil aggregate stability. Constituting 38~49% of soil mass, macroaggregates likely contributed to the nonlinear changes of aggregate stability under manure amendments. The regulatory process of GRSP allocations in soil aggregates has important implications for manure management under intensive agriculture. PMID:26423355

Long-term actuarial survivorship analysis of an interspinous stabilization system

PubMed Central

Sénégas, Jacques; Pointillart, Vincent; Mangione, Paolo

2007-01-01

In 1986, an interspinous dynamic stabilization system (the prototype of the current Wallis implant) was designed to stiffen unstable operated degenerate lumbar segments with a hard interspinous blocker to limit extension and a tension band around the spinous processes to secure the implant and limit flexion. Restoring physiological mechanical conditions to the treated level(s) while preserving some intervertebral mobility was intended to treat low-back pain related to degenerative instability without increasing stress forces in the adjacent segments. The procedure was easily reversible. If low back pain persisted or recurred, the device was removed and stability was achieved using fusion. The intermediate-term results were promising, but the long-term safety and efficacy of this dynamic interspinous stabilization device has not been previously documented. We retrospectively reviewed the hospital files of all the patients (n = 241) who had this dynamic stabilization system implanted between 1987 and 1995, contacting as many as possible to determine the actuarial survivorship of the system. In this manner, 142 of the 241 patients (58.9%) were contacted by telephone. The endpoints used for the survivorship analysis were ‘any subsequent lumbar operation’ and ‘implant removal’. At 14 years follow-up, values of actuarial survivorship with 95% confidence interval were 75.9 ± 8.3 and 81.3 ± 6.8% for the endpoints ‘any subsequent lumbar operation’ and ‘implant removal’, respectively. There was no difference in survivorship of multiple-level implants with respect to single-level devices. Although the conclusions of the present study must be tempered by the 41% attrition rate, these findings support the long-term safety of this system, and possibly long-term protective action against adjacent-level degeneration by motion preservation. Outcomes at least equivalent to those of fusion were observed without the primary drawbacks of fusion. PMID:17426988

Long-Term Dynamics of Autonomous Fractional Differential Equations

NASA Astrophysics Data System (ADS)

Liu, Tao; Xu, Wei; Xu, Yong; Han, Qun

This paper aims to investigate long-term dynamic behaviors of autonomous fractional differential equations with effective numerical method. The long-term dynamic behaviors predict where systems are heading after long-term evolution. We make some modification and transplant cell mapping methods to autonomous fractional differential equations. The mapping time duration of cell mapping is enlarged to deal with the long memory effect. Three illustrative examples, i.e. fractional Lotka-Volterra equation, fractional van der Pol oscillator and fractional Duffing equation, are studied with our revised generalized cell mapping method. We obtain long-term dynamics, such as attractors, basins of attraction, and saddles. Compared with some existing stability and numerical results, the validity of our method is verified. Furthermore, we find that the fractional order has its effect on the long-term dynamics of autonomous fractional differential equations.

Development of inexpensive metal macrocyclic complexes for use in fuel cells

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

Doddapaneni, N.; Ingersoll, D.; Kosek, J.A.

Several metal macrocyclic complexes were synthesized for use as catalysts in fuel cells. An initial evaluation of their ability to catalyze the fuel cell reactions were completed. Based on this initial evaluation, one metal macrocyclic catalyst was selected and long-term stability testing in a fuel cell was initiated. The fuel cell employing this catalyst was operated continuously for one year with little signs of catalyst degradation. The effect of synthetic reformates on the performance of the catalyst in the fuel cell environment also demonstrated high tolerance of this catalyst for common contaminants and poisons.

Meteorological fluctuations define long-term crop yield patterns in conventional and organic production systems

USDA-ARS?s Scientific Manuscript database

Periodic variability in meteorological patterns presents significant challenges to crop production consistency and yield stability. Meteorological influences on corn and soybean grain yields were analyzed over an 18-year period at a long-term experiment in Beltsville, Maryland, U.S.A., comparing c...

41 CFR 51-6.3 - Long-term procurements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Long-term procurements. 51-6.3 Section 51-6.3 Public Contracts and Property Management Other Provisions Relating to Public... ensure stability of employment and development of job skills for persons who are blind or have other...

Accelerated long-term assessment of thermal and chemical stability of bio-based phase change materials

USDA-ARS?s Scientific Manuscript database

Thermal energy storage (TES) systems incorporated with phase change materials (PCMs) have potential applications to control energy use by building envelopes. However, it is essential to evaluate long term performance of the PCMs and cost effectiveness prior to full scale implementation. For this rea...

Diagnostics and control of wavenumber stability and purity of tunable diode lasers relevant to their use as local oscillators in heterodyne systems

NASA Technical Reports Server (NTRS)

Poultney, S.; Chen, D.; Steinberg, G.; Wu, F.; Pires, A.; Miller, M. D.; Mcnally, M.

1980-01-01

Initial operation of the tunable diode lasers (TDL) showed that it was not possible to adjust the wavenumber to one selected a priori in the TDL tuning range. During operation, the operating point would change by 0.1/cm over the longer term with even larger changes occurring during some thermal cycles. Most changes during thermal cycling required using lower temperatures and higher currents to reach the former wavenumber (when it could be reached). In many cases, an operating point could be selected by changing TDL current and temperature to give both the desired wavenumber and most of the power in a single mode. The selection procedure had to be used after each thermal cycling. Wavenumber nonlinearities of about 10% over a 0.5 cm tuning range were observed. Diagnostics of the single mode selected by a grating monochromator showed wavenumber fine structure under certain operating conditions. The characteristics due to the TDL environment included short term wavenumber stability, the instrument lineshape function, and intermediate term wavenumber stability.

Stability of the Medial Olivocochlear Reflex as Measured by Distortion Product Otoacoustic Emissions

PubMed Central

Abdala, Carolina

2015-01-01

Purpose The purpose of this study was to assess the repeatability of a fine-resolution, distortion product otoacoustic emission (DPOAE)–based assay of the medial olivocochlear (MOC) reflex in normal-hearing adults. Method Data were collected during 36 test sessions from 4 normal-hearing adults to assess short-term stability and 5 normal-hearing adults to assess long-term stability. DPOAE level and phase measurements were recorded with and without contralateral acoustic stimulation. MOC reflex indices were computed by (a) noting contralateral acoustic stimulation-induced changes in DPOAE level (both absolute and normalized) at fine-structure peaks, (b) recording the effect as a vector difference, and (c) separating DPOAE components and considering a component-specific metric. Results Analyses indicated good repeatability of all indices of the MOC reflex in most frequency ranges. Short- and long-term repeatability were generally comparable. Indices normalized to a subject's own baseline fared best, showing strong short- and long-term stability across all frequency intervals. Conclusions These results suggest that fine-resolution DPOAE-based measures of the MOC reflex measured at strategic frequencies are stable, and natural variance from day-to-day or week-to-week durations is small enough to detect between-group differences and possibly to monitor intervention-related success. However, this is an empirical question that must be directly tested to confirm its utility. PMID:25320951

Aggregate Stability of Tropical Soils Under Long-Term Eucalyptus Cultivation

USDA-ARS?s Scientific Manuscript database

Eucalyptus cultivation has increased in all Brazilian regions. Despite the large amount of cultivated area, little is known about how this kind of management system affects soil properties, mainly the aggregate stability. Aggregate stability analyses have proved to be a sensitive tool to measure soi...

Long-term stabilization of place cell remapping produced by a fearful experience

PubMed Central

Wang, Melissa E.; Wann, Ellen G.; Yuan, Robin K.; Ramos Álvarez, Manuel M.; Stead, Squire M.; Muzzio, Isabel A.

2012-01-01

Fear is an emotional response to danger that is highly conserved throughout evolution because it is critical for survival. Accordingly, episodic memory for fearful locations is widely studied using contextual fear conditioning, a hippocampus-dependent task (Kim and Fanselow, 1992; Phillips and LeDoux, 1992). The hippocampus has been implicated in episodic emotional memory and is thought to integrate emotional stimuli within a spatial framework. Physiological evidence supporting the role of the hippocampus in contextual fear indicates that pyramidal cells in this region, which fire in specific locations as an animal moves through an environment, shift their preferred firing locations shortly after the presentation of an aversive stimulus (Moita et al., 2004). However, the long-term physiological mechanisms through which emotional memories are encoded by the hippocampus are unknown. Here we show that during and directly after a fearful experience, new hippocampal representations are established and persist in the long term. We recorded from the same place cells in mouse hippocampal area CA1 over several days during predator odor contextual fear conditioning and found that a subset of cells changed their preferred firing locations in response to the fearful stimulus. Furthermore, the newly formed representations of the fearful context stabilized in the long term. Our results demonstrate that place cells respond to the presence of an aversive stimulus, modify their firing patterns during emotional learning, and stabilize a long-term spatial representation in response to a fearful encounter. The persistent nature of these representations may contribute to the enduring quality of emotional memories. PMID:23136419

Molecular Bases of PDE4D Inhibition by Memory-Enhancing GEBR Library Compounds.

PubMed

Prosdocimi, Tommaso; Mollica, Luca; Donini, Stefano; Semrau, Marta S; Lucarelli, Anna Paola; Aiolfi, Egidio; Cavalli, Andrea; Storici, Paola; Alfei, Silvana; Brullo, Chiara; Bruno, Olga; Parisini, Emilio

2018-05-01

Selected members of the large rolipram-related GEBR family of type 4 phosphodiesterase (PDE4) inhibitors have been shown to facilitate long-term potentiation and to improve memory functions without causing emetic-like behavior in rodents. Despite their micromolar-range binding affinities and their promising pharmacological and toxicological profiles, few if any structure-activity relationship studies have been performed to elucidate the molecular bases of their action. Here, we report the crystal structure of a number of GEBR library compounds in complex with the catalytic domain of PDE4D as well as their inhibitory profiles for both the long PDE4D3 isoform and the catalytic domain alone. Furthermore, we assessed the stability of the observed ligand conformations in the context of the intact enzyme using molecular dynamics simulations. The longer and more flexible ligands appear to be capable of forming contacts with the regulatory portion of the enzyme, thus possibly allowing some degree of selectivity between the different PDE4 isoforms.

Curved Microneedle Array-Based sEMG Electrode for Robust Long-Term Measurements and High Selectivity

PubMed Central

Kim, Minjae; Kim, Taewan; Kim, Dong Sung; Chung, Wan Kyun

2015-01-01

Surface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode. PMID:26153773

The alarming decline of Mediterranean fish stocks.

PubMed

Vasilakopoulos, Paraskevas; Maravelias, Christos D; Tserpes, George

2014-07-21

In recent years, fisheries management has succeeded in stabilizing and even improving the state of many global fisheries resources [1-5]. This is particularly evident in areas where stocks are exploited in compliance with scientific advice and strong institutional structures are in place [1, 5]. In Europe, the well-managed northeast (NE) Atlantic fish stocks have been recovering in response to decreasing fishing pressure over the past decade [3-6], albeit with a long way to go for a universal stock rebuild [3, 7]. Meanwhile, little is known about the temporal development of the European Mediterranean stocks, whose management relies on input controls that are often poorly enforced. Here, we perform a meta-analysis of 42 European Mediterranean stocks of nine species in 1990-2010, showing that exploitation rate has been steadily increasing, selectivity (proportional exploitation of juveniles) has been deteriorating, and stocks have been shrinking. We implement species-specific simulation models to quantify changes in exploitation rate and selectivity that would maximize long-term yields and halt stock depletion. We show that stocks would be more resilient to fishing and produce higher long-term yields if harvested a few years after maturation because current selectivity is far from optimal, especially for demersal stocks. The European Common Fisheries Policy that has assisted in improving the state of NE Atlantic fish stocks in the past 10 years has failed to deliver similar results for Mediterranean stocks managed under the same policy. Limiting juvenile exploitation, advancing management plans, and strengthening compliance, control, and enforcement could promote fisheries sustainability in the Mediterranean. Copyright © 2014 Elsevier Ltd. All rights reserved.

Static Stability in the Global Upper Troposphere and Lower Stratosphere: Observations of Long-term Mean Structure and Variability using GPS Radio Occultation Data

NASA Astrophysics Data System (ADS)

Grise, K. M.; Thompson, D. W.; Birner, T.

2009-12-01

Static stability is a fundamental dynamical quantity that measures the vertical temperature stratification of the atmosphere. The long-term mean static stability field is characterized by the well-known transition from low values in the troposphere to high values in the stratosphere. However, the magnitude and structure of fine-scale static stability features near the tropopause are difficult to discern in temperature data with low vertical resolution. In this study, the authors apply over six years of high vertical resolution Global Positioning System radio occultation temperature profiles to document the long-term mean structure and variability of static stability in the global upper troposphere and lower stratosphere (UTLS). The results of this study demonstrate that a shallow but pronounced maximum in static stability exists just above the tropopause at all latitudes (i.e., the “tropopause inversion layer,” or TIL). This study also uncovers two novel aspects of static stability in the global UTLS. In the tropical lower stratosphere, the results reveal a unique vertically and horizontally varying static stability structure, with maxima located at ~17 km and ~19 km. The upper feature peaks during the NH cold season and has its largest magnitude between 10 and 15 degrees latitude in both hemispheres; the lower feature exhibits a weaker seasonal cycle and is centered at the Equator. The results also demonstrate that the strength of the TIL is closely tied to stratospheric dynamic variability. The magnitude of the TIL is enhanced following sudden stratospheric warmings in the polar regions and the easterly phase of the quasi-biennial oscillation in the tropics.

Static Stability in the Global Upper Troposphere and Lower Stratosphere: Observations of Long-term Mean Structure and Variability using GPS Radio Occultation Data

NASA Astrophysics Data System (ADS)

Grise, Kevin M.; Thompson, David W. J.; Birner, Thomas

2010-05-01

Static stability is a fundamental dynamical quantity that measures the vertical temperature stratification of the atmosphere. The long-term mean static stability field is characterized by the well-known transition from low values in the troposphere to high values in the stratosphere. However, the magnitude and structure of fine-scale static stability features near the tropopause are difficult to discern in temperature data with low vertical resolution. In this study, the authors apply over six years of high vertical resolution Global Positioning System radio occultation temperature profiles to document the long-term mean structure and variability of static stability in the global upper troposphere and lower stratosphere (UTLS). The results of this study demonstrate that a shallow but pronounced maximum in static stability exists just above the tropopause at all latitudes (i.e., the "tropopause inversion layer," or TIL). This study also uncovers two novel aspects of static stability in the global UTLS. In the tropical lower stratosphere, the results reveal a unique vertically and horizontally varying static stability structure, with maxima located at ~17 km and ~19 km. The upper feature peaks during the NH cold season and has its largest magnitude between 10 and 15 degrees latitude in both hemispheres; the lower feature exhibits a weaker seasonal cycle and is centered at the Equator. The results also demonstrate that the strength of the TIL is closely tied to stratospheric dynamic variability. The magnitude of the TIL is enhanced following sudden stratospheric warmings in the polar regions and the easterly phase of the quasi-biennial oscillation in the tropics.

Long-term outcome of patients with dysthymia and panic disorder: a naturalistic 9-year follow-up study.

PubMed

Svanborg, Cecilia; Wistedt, Anna Aberg; Svanborg, Pär

2008-01-01

The highly prevalent psychiatric disorders dysthymia and panic disorder have often a chronic or recurrent course with superimposed major depression. The prominent comorbidity between these diagnoses constitutes a confounding factor in the study of long-term outcome. We performed a 9-year follow-up of 38 patients with "pure" diagnoses, i.e. without comorbid dysthymia and panic disorder, selected from two 2-year naturalistic treatment studies with psychotherapy and antidepressant medication. The aims of the present study were to investigate 1) the stability of change, and 2) the impact of comorbid personality disorders (PDs) on long-term outcome. Patients were reassessed with SCID-I and SCID-II interviews, SCL-90/BSI and a detailed, modified life-charting interview, investigating course and treatment over time. About 50% of patients showed substantial improvement, of whom about half were in remission. Comorbid PD was a negative prognostic factor independently of Axis I diagnosis. Although patients with panic disorder had a lower frequency of comorbid PD, later onset, shorter duration of illness and better outcome after the original studies, there was no difference in the long-term outcome. The less stable outcome among panic patients suggests that standard treatments are not resulting in enduring remission. In order to achieve remission, it is necessary to 1) address comorbid PDs, 2) perform careful assessments of all comorbid diagnoses, and 3) build routines for the follow-up and augmentation of treatments.

Long-term surgical-orthodontic management of hemimandibular hyperplasia.

PubMed

Bennett, Samuel C; Goonewardene, Mithran S

2016-05-01

Hemimandibular hyperplasia (HH), also known as hemimandibular hypertrophy, is characterised by excessive unilateral three-dimensional growth of the mandible after birth. Vertical unilateral elongation of the mandible becomes clinically evident as a rare form of vertical facial asymmetry. Aberrant growth of the facial skeleton affects the developing dentition and the dental compensatory mechanism is usually unable to maintain optimal occlusal relationships. The resulting malocclusion is effectively managed by combined surgical-orthodontic care to address the facial, skeletal and dental problems that confront clinicians. Orthodontists are advised to assess patients with HH during the post-treatment retention stage for continuing mandibular growth and assess the stability of treatment outcomes with long-term follow-up and records as required. To present a case of hemimandibular hyperplasia treated successfully by combined surgical-orthodontic care and evaluated for stability over a seven-year follow-up period. Surgical-orthodontic management was accomplished in four stages: 1) pre-surgical orthodontic; 21 surgical; 3) post-surgical orthodontic; and 4) post-treatment orthodontic retention. Complete orthodontic records, including extra- and intra-oral photographs, study models, and cephalograms plus panoramic radiographs were taken at the pretreatment, post-treatment, and seven-year orthodontic retention time-points. Facial, skeletal and dental goals were achieved in the three planes of space and the long-term stability of the treatment results was shown during a post-treatment orthodontic retention period of seven years. Hemimandibular hyperplasia is a true growth anomaly which may be managed effectively. Clinicians may expect successful long-term correction and stability by utilising a comprehensive surgical-orthodontic treatment approach.

Dual-Function Au@Y2O3:Eu3+ Smart Film for Enhanced Power Conversion Efficiency and Long-Term Stability of Perovskite Solar Cells.

PubMed

Kim, Chang Woo; Eom, Tae Young; Yang, In Seok; Kim, Byung Su; Lee, Wan In; Kang, Yong Soo; Kang, Young Soo

2017-07-28

In the present study, a dual-functional smart film combining the effects of wavelength conversion and amplification of the converted wave by the localized surface plasmon resonance has been investigated for a perovskite solar cell. This dual-functional film, composed of Au nanoparticles coated on the surface of Y 2 O 3 :Eu 3+ phosphor (Au@Y 2 O 3 :Eu 3+ ) nanoparticle monolayer, enhances the solar energy conversion efficiency to electrical energy and long-term stability of photovoltaic cells. Coupling between the Y 2 O 3 :Eu 3+ phosphor monolayer and ultraviolet solar light induces the latter to be converted into visible light with a quantum yield above 80%. Concurrently, the Au nanoparticle monolayer on the phosphor nanoparticle monolayer amplifies the converted visible light by up to 170%. This synergy leads to an increased solar light energy conversion efficiency of perovskite solar cells. Simultaneously, the dual-function film suppresses the photodegradation of perovskite by UV light, resulting in long-term stability. Introducing the hybrid smart Au@Y 2 O 3 :Eu 3+ film in perovskite solar cells increases their overall solar-to-electrical energy conversion efficiency to 16.1% and enhances long-term stability, as compared to the value of 15.2% for standard perovskite solar cells. The synergism between the wavelength conversion effect of the phosphor nanoparticle monolayer and the wave amplification by the localized surface plasmon resonance of the Au nanoparticle monolayer in a perovskite solar cell is comparatively investigated, providing a viable strategy of broadening the solar spectrum utilization.

The mechanical stability of polyimide films at high pH

NASA Technical Reports Server (NTRS)

Croall, Catharine I.; St.clair, Terry L.

1990-01-01

Polyimide insulated electrical wire has been widely used in the aerospace industry in commercial, military, and to a lesser degree, general aviation aircraft since the early 1970s. Wiring failures linked to insulation damage have drawn much attention in the media and concerns have developed regarding the long term stability and safety of polyimide insulated electrical wire. The mechanical durability and chemical stability of polyimide insulated wire are affected by hydrolysis, notch propagation, wet and dry arc tracking, topcoat flaking, and degradation due to high pH fluids. Several polyimides were selected for evaluation for resistance to degradation by various aqueous alkaline solutions. The polyimides under evaluation include commercially available films such as KAPTON (tradename), APICAL (tradename), LARC-TPI, and UPILEX (tradename) R and S, as well as a number of experimental films prepared at NASA-Langley. Material properties investigated include viscosity, solubility, moisture absorption, glass transition temperature, dielectric constant, and mechanical properties before and after exposure to various conditions.

Performance and stability of a liquid anode high-temperature metal-air battery

NASA Astrophysics Data System (ADS)

Otaegui, L.; Rodriguez-Martinez, L. M.; Wang, L.; Laresgoiti, A.; Tsukamoto, H.; Han, M. H.; Tsai, C.-L.; Laresgoiti, I.; López, C. M.; Rojo, T.

2014-02-01

A High-Temperature Metal-Air Battery (HTMAB) that operates based on a simple redox reaction between molten metal and atmospheric oxygen at 600-1000 °C is presented. This innovative HTMAB concept combines the technology of conventional metal-air batteries with that of solid oxide fuel cells to provide a high energy density system for many applications. Electrochemical reversibility is demonstrated with 95% coulomb efficiency. Cell sealing has been identified as a key issue in order to determine the end-of-charge voltage, enhance coulomb efficiency and ensure long term stability. In this work, molten Sn is selected as anode material. Low utilization of the stored material due to precipitation of the SnO2 on the electrochemically active area limits the expected capacity, which should theoretically approach 903 mAh g-1. Nevertheless, more than 1000 charge/discharge cycles are performed during more than 1000 h at 800 °C, showing highly promising results of stability, reversibility and cyclability.

Integrating plant-microbe interactions to understand soil C stabilization with the MIcrobial-MIneral Carbon Stabilization model (MIMICS)

NASA Astrophysics Data System (ADS)

Grandy, Stuart; Wieder, Will; Kallenbach, Cynthia; Tiemann, Lisa

2014-05-01

If soil organic matter is predominantly microbial biomass, plant inputs that build biomass should also increase SOM. This seems obvious, but the implications fundamentally change how we think about the relationships between plants, microbes and SOM. Plant residues that build microbial biomass are typically characterized by low C/N ratios and high lignin contents. However, plants with high lignin contents and high C/N ratios are believed to increase SOM, an entrenched idea that still strongly motivates agricultural soil management practices. Here we use a combination of meta-analysis with a new microbial-explicit soil biogeochemistry model to explore the relationships between plant litter chemistry, microbial communities, and SOM stabilization in different soil types. We use the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, newly built upon the Community Land Model (CLM) platform, to enhance our understanding of biology in earth system processes. The turnover of litter and SOM in MIMICS are governed by the activity of r- and k-selected microbial groups and temperature sensitive Michaelis-Menten kinetics. Plant and microbial residues are stabilized short-term by chemical recalcitrance or long-term by physical protection. Fast-turnover litter inputs increase SOM by >10% depending on temperature in clay soils, and it's only in sandy soils devoid of physical protection mechanisms that recalcitrant inputs build SOM. These results challenge centuries of lay knowledge as well as conventional ideas of SOM formation, but are they realistic? To test this, we conducted a meta-analysis of the relationships between the chemistry of plant liter inputs and SOM concentrations. We find globally that the highest SOM concentrations are associated with plant inputs containing low C/N ratios. These results are confirmed by individual tracer studies pointing to greater stabilization of low C/N ratio inputs, particularly in clay soils. Our model and meta-analysis results suggest that current ideas about plant-microbe-SOM relationships are unraveling. If so, our reconsideration of the mechanisms stabilizing SOM will also challenge long-held views about how to optimize plant community management to increase SOM.

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 Monitoring of Brain Dopamine Metabolism In Vivo with Carbon Paste Electrodes

PubMed Central

O'Neill, Robert D.

2005-01-01

This review focuses on the stability of voltammetric signals recorded over periods of months with carbon paste electrodes (CPEs) implanted in the brain. The key interaction underlying this stability is between the pasting oil and brain lipids that are capable of inhibiting the fouling caused by proteins. In brain regions receiving a significant dopaminergic input, a peak due to the methylated metabolites of dopamine, principally homovanillic acid (HVA), is clearly resolved using slow sweep voltammetry. Although a number of factors limit the time resolution for monitoring brain HVA concentration dynamics, the stability of CPEs allows investigations of long-term effects of drugs, as well as behavioral studies, not possible using other in-vivo monitoring techniques.

Long-term characterization of neural electrodes based on parylene-caulked polydimethylsiloxane substrate.

PubMed

Jeong, Jinmo; Chou, Namsun; Kim, Sohee

2016-06-01

This study investigates the mechanical and long-term electrical properties of parylene-caulked polydimethylsiloxane (PDMS) as a substrate for implantable electrodes. The parylene-caulked PDMS is a structure where particles of parylene fill the porous surface of PDMS. This material is expected to have low water absorption and desirable mechanical properties such as flexibility and elasticity that are beneficial in many biomedical applications. To evaluate the mechanical property and electrical stability of parylene-caulked PDMS for potential in-vivo uses, tensile tests were conducted firstly, which results showed that the mechanical strength of parylene-caulked PDMS was comparable to that of native PDMS. Next, surface electrodes based on parylene-caulked PDMS were fabricated and their impedance was measured in phosphate-buffered saline (PBS) solution at 36.5 °C over seven months. The electrodes based on parylene-caulked PDMS exhibited the improved stability in impedance over time than native PDMS. Thus, with improved electrical stability in wet environment and preserved mechanical properties of PDMS, the electrodes based on parylene-caulked PDMS are expected to be suitable for long-term in-vivo applications.

Decomposition of heterogeneous organic matterand its long-term stabilization in soils

USGS Publications Warehouse

Sierra, Carlos A.; Harmon, Mark E.; Perakis, Steven S.

2011-01-01

Soil organic matter is a complex mixture of material with heterogeneous biological, physical, and chemical properties. Decomposition models represent this heterogeneity either as a set of discrete pools with different residence times or as a continuum of qualities. It is unclear though, whether these two different approaches yield comparable predictions of organic matter dynamics. Here, we compare predictions from these two different approaches and propose an intermediate approach to study organic matter decomposition based on concepts from continuous models implemented numerically. We found that the disagreement between discrete and continuous approaches can be considerable depending on the degree of nonlinearity of the model and simulation time. The two approaches can diverge substantially for predicting long-term processes in soils. Based on our alternative approach, which is a modification of the continuous quality theory, we explored the temporal patterns that emerge by treating substrate heterogeneity explicitly. The analysis suggests that the pattern of carbon mineralization over time is highly dependent on the degree and form of nonlinearity in the model, mostly expressed as differences in microbial growth and efficiency for different substrates. Moreover, short-term stabilization and destabilization mechanisms operating simultaneously result in long-term accumulation of carbon characterized by low decomposition rates, independent of the characteristics of the incoming litter. We show that representation of heterogeneity in the decomposition process can lead to substantial improvements in our understanding of carbon mineralization and its long-term stability in soils.

Measuring and communicating meaningful outcomes in neonatology: A family perspective.

PubMed

Janvier, Annie; Farlow, Barbara; Baardsnes, Jason; Pearce, Rebecca; Barrington, Keith J

2016-12-01

Medium- and long-term outcomes have been collected and described among survivors of neonatal intensive care units for decades, for a number of purposes: (1) quality control within units, (2) comparisons of outcomes between NICUs, (3) clinical trials (whether an intervention improves outcomes), (4) end-of-life decision-making, (5) to better understand the effects of neonatal conditions and/or interventions on organs and/or long-term health, and finally (6) to better prepare parents for the future. However, the outcomes evaluated have been selected by investigators, based on feasibility, availability, cost, stability, and on what investigators consider to be important. Many of the routinely measured outcomes have major limitations: they may not correlate well with long-term difficulties, they may artificially divide continuous outcomes into dichotomous ones, and may have no clear relationship with quality of life and functioning of children and their families. Several investigations, such as routine term cerebral resonance imaging for preterm infants, have also not yet been shown to improve the outcome of children nor their families. In this article, the most common variables used in neonatology as well as some variables which are rarely measured but may be of equal importance for families are presented. The manner in which these outcomes are communicated to families will be examined, as well as recommendations to optimize communication with parents. Copyright © 2016 Elsevier Inc. All rights reserved.

Application of micro-porous polycarbonate membranes in dye-sensitized solar cells: Cell performance and long-term stability

NASA Astrophysics Data System (ADS)

Lue, Shingjiang Jessie; Lo, Pei Wen; Hung, Ling-Yung; Tung, Yung Liang

This research investigates the cell performance and long-term stability of dye-sensitized solar cells (DSSCs) containing micro-porous polycarbonate (PC) film as the frame work material to stabilize the electrolyte solution. The track-etched PC film has cylindrical pore geometry, which is beneficial for ion transport in the electrolyte trapped inside the PC film. The photovoltaic efficiency of the DSSC with 0.2-μm PC membrane is 5.75 ± 0.73% under irradiation of 100 mW cm -2, which is slightly lower than that (6.34 ± 0.44%) of cells without PC film. The differences in fill factor and open-circuit voltage between the DSSCs with and without PC film are not statistically significant. The long-term cell performance is carried out at continuous illumination of 100 mW cm -2 (1 sun) and in darkness at 60 °C for up to 1000 h. There is no significant efficiency difference between the cells with and without PC film in light soaking (4.33% vs. 4.52%) for 960 h. In darkness, however, the cells with PC film demonstrate much higher efficiency (at 2.37%) than cells without PC (0.85%) after 1000 h. The improved long-term efficiency data and the higher percentage of working cells confirm the superior lifetime and performance using the micro-porous PC film.

Body size evolution in an old insect order: No evidence for Cope's Rule in spite of fitness benefits of large size.

PubMed

Waller, John T; Svensson, Erik I

2017-09-01

We integrate field data and phylogenetic comparative analyses to investigate causes of body size evolution and stasis in an old insect order: odonates ("dragonflies and damselflies"). Fossil evidence for "Cope's Rule" in odonates is weak or nonexistent since the last major extinction event 65 million years ago, yet selection studies show consistent positive selection for increased body size among adults. In particular, we find that large males in natural populations of the banded demoiselle (Calopteryx splendens) over several generations have consistent fitness benefits both in terms of survival and mating success. Additionally, there was no evidence for stabilizing or conflicting selection between fitness components within the adult life-stage. This lack of stabilizing selection during the adult life-stage was independently supported by a literature survey on different male and female fitness components from several odonate species. We did detect several significant body size shifts among extant taxa using comparative methods and a large new molecular phylogeny for odonates. We suggest that the lack of Cope's rule in odonates results from conflicting selection between fitness advantages of large adult size and costs of long larval development. We also discuss competing explanations for body size stasis in this insect group. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

ASSESSMENT OF MOLECULAR GENETIC STABILITY BETWEEN LONG-TERM CRYOPRESERVED AND TISSUE CULTURED WASABI (Wasabia japonica) PLANTS.

PubMed

Maki, S; Hirai, Y; Niino, T; Matsumoto, T

2015-01-01

Maintaining the genetic integrity in long-term tissue cultured and cryopreserved plants is important for the conservation of plant genetic resources. In this study, the genetic stability of cryopreserved wasabi shoot tips stored for 10 years at -150 degree C was visualized using Amplified Fragment Length Polymorphism (AFLP) and Methylation Sensitive Amplified Polymorphism (MSAP). The study included plants derived from cryopreserved shoot tips after 10.5 years storage at -150 degree C (LN10yr), after 2 h storage at -196 degree C (LN2hr), cryopreservation controls (No LN cooling (TC)) and non-treated controls without LN cooling (LC). The donor plants for LN2hr, TC and LC were also maintained in vitro at 20 degree C for the same period. Neither technique detected genetic variations in either control or cryopreserved plants. Some mutations were noted in plants maintained in tissue culture for 10 years. Comparison of genome stability for TC and LN2hr plants showed only a minor change in DNA. However, when comparing the LC and Ln10yr, many differences were found. We conclude that cryopreservation is a superior conservation method compared to tissue culture in maintaining genetic stability for a long-term storage of wasabi germplasm.

Effect of mesogenic ligands on short and long-term spectral stability of CdSe/ZnS quantum dots

NASA Astrophysics Data System (ADS)

Amaral, Jose; Betady, Edwin; Quint, Makiko; Martin, Denzal; Riahinasab, Sheida; Hirst, Linda; Ghosh, Sayantani

Surface modification of chemically synthesized CdSe/ZnS quantum dots (QDs) by performing a ligand-exchange can improve the optical properties, including short- and long-term photo-stability. Using a custom-designed mesogenic ligand, we significantly and advantageously alter the photophysical properties of CdSe/ZnS core-shell QDs. Our investigation is two-fold, as we follow the effect of ligand exchange on (1) the static and dynamic photoluminescence (PL) properties of QDs under continuous illumination, and (2) the temperature dependence of PL. We find that a reduction in Forster resonance energy transfer due to the ligand exchange process results in stabilizing both recombination lifetimes and emission intensity for over an hour of high power photo-excitation. Our temperature-dependent PL studies indicate thermally activated PL recovery at higher temperatures, and a lack of emission enhancement at low temperatures resulting from greater charge separation by the mesogenic ligands. We conclude that this process improves photoluminescence stability and sample longevity of QD films whose applications require long term resistance to photobleaching. This research was supported by funds from the National Aeronautics and Space Administration (NASA) Grant No. NNX15AQ01A, UCMEXUS-CONACYT, and National Science Foundation (NSF) Grants No. DMR-1056860, DMR-1359406 and CBET-1507551.

Long-Term Stability of Tutor Performance.

ERIC Educational Resources Information Center

Dolmans, Diana H. J. M.; And Others

1996-01-01

Examined the extent to which tutor ratings remained stable in the long term by evaluating 291 ratings of 140 tutors at Maastricht University in the Netherlands between 1992 and 1995. The results indicated that, if the aggregated score and overall judgement are used to interpret the precision of individual scores, four and two occasions,…

Satb2 determines miRNA expression and long-term memory in the adult central nervous system.

PubMed

Jaitner, Clemens; Reddy, Chethan; Abentung, Andreas; Whittle, Nigel; Rieder, Dietmar; Delekate, Andrea; Korte, Martin; Jain, Gaurav; Fischer, Andre; Sananbenesi, Farahnaz; Cera, Isabella; Singewald, Nicolas; Dechant, Georg; Apostolova, Galina

2016-11-29

SATB2 is a risk locus for schizophrenia and encodes a DNA-binding protein that regulates higher-order chromatin configuration. In the adult brain Satb2 is almost exclusively expressed in pyramidal neurons of two brain regions important for memory formation, the cerebral cortex and the CA1-hippocampal field. Here we show that Satb2 is required for key hippocampal functions since deletion of Satb2 from the adult mouse forebrain prevents the stabilization of synaptic long-term potentiation and markedly impairs long-term fear and object discrimination memory. At the molecular level, we find that synaptic activity and BDNF up-regulate Satb2, which itself binds to the promoters of coding and non-coding genes. Satb2 controls the hippocampal levels of a large cohort of miRNAs, many of which are implicated in synaptic plasticity and memory formation. Together, our findings demonstrate that Satb2 is critically involved in long-term plasticity processes in the adult forebrain that underlie the consolidation and stabilization of context-linked memory.

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

Mancini, Alessandro; Felice, Valeria; Natali Sora, Isabella

Chemical reactivity between cathodes and electrolytes is a crucial issue for long term SOFCs stability and performances. In this study, chemical reactivity between selected cathodic materials and the ionic conducting melilite La{sub 1.50}Sr{sub 0.50}Ga{sub 3}O{sub 7.25} has been extensively investigated by X-ray powder diffraction in a wide temperature range (up to 1573 K). Perovskite-type La{sub 0.8}Sr{sub 0.2}MnO{sub 3−d} and La{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−d} and K{sub 2}NiF{sub 4}-type La{sub 2}NiO{sub 4+d} were selected as cathode materials. The results of this study allow identifying the most suitable electrode material to be used in combination with the melilite-type gallate electrolyte andmore » set the basis for future work on this novel system. - Graphical abstract: Chemical reactivity between cathodes and electrolytes is a crucial issue for long term SOFCs stability and performances. In this study, chemical reactivity between selected cathodic materials and the ionic conducting melilite La{sub 1.50}Sr{sub 0.50}Ga{sub 3}O{sub 7.25} has been extensively investigated by means of X-ray powder diffraction. - Highlights: • Chemical compatibility between melilite-type gallate and cathodes for SOFCs up to 1573 K. • No reactivity observed between La{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}Cu{sub 0.2}O{sub 3−d} and La{sub 1.50}Sr{sub 0.50}Ga{sub 3}O{sub 7.25}. • Reactivity observed between La{sub 0.80}Sr{sub 0.20}MnO{sub 3−d} and La{sub 1.50}Sr{sub 0.50}Ga{sub 3}O{sub 7.25}. • Significant reactivity observed between La{sub 2}NiO{sub 4+d} and La{sub 1.50}Sr{sub 0.50}Ga{sub 3}O{sub 7.25}.« less

Ability of various materials to detect explosive vapors by fluorescent technologies: a comparative study.

PubMed

Bouhadid, Myriam; Caron, Thomas; Veignal, Florian; Pasquinet, Eric; Ratsimihety, Amédée; Ganachaud, François; Montméat, Pierre

2012-10-15

For the development of fluorescent sensors, one of the key points is choosing the sensitive material. In this article, we aim at evaluating, under strictly identical experimental conditions, the performance of three materials for the detection of dinitrotoluene (a volatile marker of trinitrotoluene) through different parameters: response time, fluorescence intensity, sensitivity, reversibility, reaction after successive exposures and long-term stability. The results are discussed according to the nature of the sensitive materials. This first study rendered it possible to select a conjugated molecule as the best sensitive material for the development of a lab-made prototype. In a second part, the selectivity of this particular sensitive material was studied and its ability to detect TNT could be demonstrated. Copyright © 2012. Published by Elsevier B.V.

Evidence of susceptibility to lamivudine-based HAART and genetic stability of hepatitis B virus (HBV) in HIV co-infected patients: A South African longitudinal HBV whole genome study.

PubMed

Amponsah-Dacosta, Edina; Rakgole, J Nare; Gededzha, Maemu P; Lukhwareni, Azwidowi; Blackard, Jason T; Selabe, Selokela G; Mphahlele, M Jeffrey

2016-09-01

Reports on the concomitant impact of HIV co-infection and long term highly active anti-retroviral therapy (HAART) on the genetic stability and molecular evolution of HBV are limited in sub-Saharan Africa. This retrospective study investigated the molecular evolution of chronic HBV in HIV co-infected patients on lamivudine (3TC)-based HAART over a 5year period. Four HIV co-infected patients, consecutively recruited and followed-up, were screened for hepatitis B serological markers, and their viral loads determined. The HBV genome was amplified from longitudinal samples and characterized by Bayesian inference, mutational analysis, and identification of immune selection pressure. All patients exhibited persistent chronic HBV infection at baseline, as well as over the course of follow-up despite exposure to 3TC-based HAART. The polymerase gene in all isolates was relatively variable prior to HAART initiation at baseline and during the course of follow-up, although primary drug resistance mutations were not detected. All but one patient were infected with HBV subgenotype A1. The divergence rates between baseline and the last follow-up sequences ranged from 0 to 2.0×10(-3) substitutions per site per year (s/s/y). Positive selection pressure was evident within the surface and core genes. Despite persistent HBV infection in the HIV co-infected patients exposed to long term 3TC-based HAART, the molecular evolution of HBV over a 5year period was unremarkable. In addition, HBV exhibited minimal genetic variability overtime. Copyright © 2016 Elsevier B.V. All rights reserved.

Stability of Uncemented Cups - Long-Term Effect of Screws, Pegs and HA Coating: A 14-Year RSA Follow-Up of Total Hip Arthroplasty.

PubMed

Otten, Volker T C; Crnalic, Sead; Röhrl, Stephan M; Nivbrant, Bo; Nilsson, Kjell G

2016-01-01

Screws, pegs and hydroxyapatite-coating are used to enhance the primary stability of uncemented cups. We present a 14-year follow-up of 48 hips randomized to four groups: press-fit only, press-fit plus screws, press-fit plus pegs and hydroxyapatite-coated cups. Radiostereometric migration measurements showed equally good stability regardless cup augmentation. The mean wear rate was high, 0.21 mm/year, with no differences between the groups. Seven hips had radiographical osteolysis but only in hips with augmented cups. Cups without screw-holes compared with cups with screw-holes resulted in better clinical outcome at the 14-year follow-up. Thus, augmentation of uncemented cups with screws, pegs, or hydroxyapatite did not appear to improve the long-term stability compared with press-fit only. Copyright © 2016 Elsevier Inc. All rights reserved.

Stable radio-frequency transfer over optical fiber by phase-conjugate frequency mixing.

PubMed

He, Yabai; Orr, Brian J; Baldwin, Kenneth G H; Wouters, Michael J; Luiten, Andre N; Aben, Guido; Warrington, R Bruce

2013-08-12

We demonstrate long-distance (≥100-km) synchronization of the phase of a radio-frequency reference over an optical-fiber network without needing to actively stabilize the optical path length. Frequency mixing is used to achieve passive phase-conjugate cancellation of fiber-length fluctuations, ensuring that the phase difference between the reference and synchronized oscillators is independent of the link length. The fractional radio-frequency-transfer stability through a 100-km "real-world" urban optical-fiber network is 6 × 10(-17) with an averaging time of 10(4) s. Our compensation technique is robust, providing long-term stability superior to that of a hydrogen maser. By combining our technique with the short-term stability provided by a remote, high-quality quartz oscillator, this system is potentially applicable to transcontinental optical-fiber time and frequency dissemination where the optical round-trip propagation time is significant.

A role of abdomen in butterfly's flapping flight

NASA Astrophysics Data System (ADS)

Jayakumar, Jeeva; Senda, Kei; Yokoyama, Naoto

2017-11-01

Butterfly's forward flight with periodic flapping motion is longitudinally unstable, and control of the thoracic pitching angle is essential to stabilize the flight. This study aims to comprehend roles which the abdominal motion play in the pitching stability of butterfly's flapping flight by using a two-dimensional model. The control of the thoracic pitching angle by the abdominal motion is an underactuated problem because of the limit on the abdominal angle. The control input of the thorax-abdomen joint torque is obtained by the hierarchical sliding mode control in this study. Numerical simulations reveal that the control by the abdominal motion provides short-term pitching stabilization in the butterfly's flight. Moreover, the control input due to a large thorax-abdomen joint torque can counteract a quite large perturbation, and can return the pitching attitude to the periodic trajectory with a short recovery time. These observations are consistent with biologists' view that living butterflies use their abdomens as rudders. On the other hand, the abdominal control mostly fails in long-term pitching stabilization, because it cannot directly alter the aerodynamic forces. The control for the long-term pitching stabilization will also be discussed.

Thermal and physicochemical properties important for the long term behavior of nuclear waste glasses

NASA Astrophysics Data System (ADS)

Matzke, Hj.; Vernaz, E.

High level nuclear waste from reprocessing of spent nuclear fuel has to be solidified in a stable matrix for safe long-time storage. Vitrification in borosilicate glasses is the technique accepted worldwide as the best combination of engineering constraints from fabrication and physicochemical properties of the matrix. A number of different glasses was developed in different national programs. The criteria and the reasons for selecting the final compositions are described briefly. Emphasis is placed on the French product R7T7 and on thermal and physicochemical properties though glasses developed in other national projects (e.g., the German product GP 98/12, etc.) are also treated. The basic physical and mechanical properties and the chemical durability of the glass in contact with water are described. The basic mechanisms of aqueous corrosion are discussed and the evolving modelling of the leaching process is dealt with, as well as effects of container material, backfill, etc. The thermal behavior has also been studied and extensive data exist on diffusion of glass constituents (Na) and of interesting elements of the waste such as the alkalis Rb and Cs or the actinides U and Pu, as well as on crystallization processes in the glass during storage at elevated temperatures. Emphasis is placed on the radiation stability of the glasses, based on extensive studies using short-lived actinides (e.g., 244Cm) or ion implantation to produce the damage expected during long storage at an accelerated rate. The radiation stability is shown to be very good, if realistic damage conditions are used. The knowledge accumulated in the past years is used to evaluate and predict the long-term evolution of the glass under storage conditions.

Maintenance therapy with second generation antipsychotics for bipolar disorder - A systematic review and meta-analysis.

PubMed

Lindström, Leif; Lindström, Eva; Nilsson, Mikael; Höistad, Malin

2017-04-15

Second generations antipsychotics (SGA) are frequently used for maintenance treatment in bipolar disorder. We systematically reviewed the efficacy and long-term effects of treatment with SGA, regardless of treatment strategy (SGA administered either as monotherapy or as adjunctive therapy), in comparison to placebo, lithium or valproate. Primary outcomes were relapses (mood episode recurrence) and discontinuation. Clinical studies were identified through database searching in PubMed, Embase, PsychInfo and Cochrane Library and critically appraised based on the Cochrane Handbook. Full data extraction of raw data was performed and analyzed with meta-analyses, and level of evidence graded using GRADE. Only randomized controlled studies (RCT) and observational studies were included, with a minimum follow-up of 6 months. Comparators used were restricted to placebo, lithium, valproate or other anti-epileptic drugs. We identified 15 RCTs on SGA in bipolar disorder with follow-up-time of 6 months up to 2 years, and one observational study reporting long-term effects of up to 4 years. A total of 6142 patients were included in the randomized trials. No long-term RCTs beyond 2 years follow-up was identified. All RCTs except for one included patients with bipolar disorder type I only. All RCTs except for two included patients pre-stabilized on the drug under investigation prior to randomization (enrichment design). For SGA as adjunctive therapy to lithium or valproate, meta-analyses showed that treatment with either aripiprazole (RR: 0.65, 95% CI 0.50-0.85), quetiapine (RR: 0.38, 95% CI 0.32-0.46) or ziprasidone (RR: 0.62, 95% CI 0.40-0.96) reduced the overall risk of relapses in patients that had responded during the stabilization phase. Adjunctive therapy with quetiapine was the only drug that reduced both manic and depressive episodes. For SGA as monotherapy, only quetiapine was shown to be better than lithium/ valproate for both manic and depressive relapses, but only for patients stabilized on quetiapine during the acute phase. As monotherapy, olanzapine, quetiapine and risperidone were shown to be superior to placebo in reducing the overall risk of relapses. There were considerable limitations to the evidence base of maintenance treatment with SGA in bipolar disorder. Most studies used stabilized patients, i.e. enrichment design (selection bias), had considerable dropout levels (attrition bias), and variable degree of reporting bias. No long-term RCT data on efficacy is available beyond 2 years, and almost all studies are on bipolar disorder type I patients only. Despite these limitations, we elucidate quantitative findings from meta-analyses conducted on the randomized trials published on the topic. Copyright © 2017 Elsevier B.V. All rights reserved.

Microstructural Changes in Inconel 740 After Long-Term Aging in the Presence and Absence of Stress

NASA Astrophysics Data System (ADS)

Unocic, K. A.; Shingledecker, J. P.; Tortorelli, P. F.

2014-12-01

The Ni-based alloy, Inconel® 740, is being extensively examined for use in advanced ultrasupercritical steam boilers because its precipitation-strengthened microstructure appears to offer the necessary creep strength under the high temperatures and pressures (up to 760°C and 35 MPa) needed for high efficiency power generation. However, because this application requires extremely long lifetimes under these conditions (up to 30 years), long-term microstructure stability is a major concern. In this paper, results from microstructural analyses of Inconel 740 specimens aged at 700 and 750°C in the presence and absence of creep loading for times up to ~31,000 h are presented. The primary focus was on the development of the eta η (Ni3Ti) phase and coarsening of coherent γ'-Ni3(Al,Ti) precipitates and its depletion near eta/matrix interfaces. However, despite these processes, Inconel 740 showed adequate long-term microstructural stability to assure adequate creep strength for the intended application.

Highly Efficient Gas-Phase Oxidation of Renewable Furfural to Maleic Anhydride over Plate Vanadium Phosphorus Oxide Catalyst.

PubMed

Li, Xiukai; Ko, Jogie; Zhang, Yugen

2018-02-09

Maleic anhydride (MAnh) and its acids are critical intermediates in chemical industry. The synthesis of maleic anhydride from renewable furfural is one of the most sought after processes in the field of sustainable chemistry. In this study, a plate vanadium phosphorus oxide (VPO) catalyst synthesized by a hydrothermal method with glucose as a green reducing agent catalyzes furfural oxidation to MAnh in the gas phase. The plate catalyst-denoted as VPO HT -has a preferentially exposed (200) crystal plane and exhibited dramatically enhanced activity, selectivity and stability as compared to conventional VPO catalysts and other state-of-the-art catalytic systems. At 360 °C reaction temperature with air as an oxidant, about 90 % yield of MAnh was obtained at 10 vol % of furfural in the feed, a furfural concentration value that is much higher than those (<2 vol %) reported for other catalytic systems. The catalyst showed good long-term stability and there was no decrease in activity or selectivity for MAnh during the time-on-stream of 25 h. The high efficiency and catalyst stability indicate the great potential of this system for the synthesis of maleic anhydride from renewable furfural. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A combined interfacial and in-situ polymerization strategy to construct well-defined core-shell epoxy-containing SiO2-based microcapsules with high encapsulation loading, super thermal stability and nonpolar solvent tolerance

NASA Astrophysics Data System (ADS)

Jia; Wang; Tian; Li; Xu; Jiao; Cao; Wu

2016-10-01

SiO2-based microcapsules containing hydrophobic molecules exhibited potential applications such as extrinsic self-healing, drug delivery, due to outstanding thermal and chemical stability of SiO2. However, to construct SiO2-based microcapsules with both high encapsulation loading and long-term structural stability is still a troublesome issue, limiting their further utilization. We herein design a single-batch route, a combined interfacial and in-situ polymerization strategy, to fabricate epoxy-containing SiO2-based microcapsules with both high encapsulation loading and long-term structural stability. The final SiO2-based microcapsules preserve high encapsulation loading of 85.7 wt% by controlling exclusively hydrolysis and condensed polymerization at oil/water interface in the initial interfacial polymerization step. In the subsequent in-situ polymerization step, the initial SiO2-based microcapsules as seeds could efficiently harvest SiO2 precursors and primary SiO2 particles to finely tune the SiO2 wall thickness, thereby enhancing long-term structural stability of the final SiO2-based microcapsules including high thermal stability with almost no any weight loss until 250°C, and strong tolerance against nonpolar solvents such as CCl4 with almost unchanged core-shell structure and unchanged core weight after immersing into strong solvents for up to 5 days. These SiO2-based microcapsules are extremely suited for processing them into anticorrosive coating in the presence of nonpolar solvents for self-healing application.

Accurate Determination of Soluble Axl by Enzyme-Linked Immunosorbent Assay.

PubMed

Dengler, Mirko; Huber, Heidemarie; Müller, Christian J; Zellmer, Angela; Rauch, Peter; Mikulits, Wolfgang

2016-11-01

Levels of soluble Axl (sAxl) are routinely assessed in human sera by sandwich enzyme-linked immunosorbent assay (ELISA). Although sAxl values are suggested to diagnose different types of disorders, no uniform ELISA method is available, allowing the reliable interassay comparison between results. Furthermore, little is known about the stability of sAxl under storage conditions, which is a relevant parameter for biomedical trials. The evaluation of sAxl stability under various stress conditions and the determination of proper conditions to use the sAxl ELISA for routine clinical applications are of great interest. In this study, serum samples were subjected to freeze-thaw cycles and incubation at different temperatures to analyze the stability of sAxl by ELISA. Dilution and spike-in experiments were carried out to examine the impact of serum and diluent components on the ELISA performance. Various diluents and media were employed to resolve masking effects of the serum. The assay components were further optimized for long-term usability by treatment with stabilizers and validation under temperature stress. Indeed, sAxl showed long-term stability in serum during freeze-thaw cycles and incubation under temperature stress conditions. The dilution experiments revealed that unknown components in the serum caused masking effects that can be reduced by proper dilutions. The assay performance was further increased by using a standardized buffer system to dilute serum samples. Stabilization of coated plates and of streptavidin-horseradish peroxidase allowed long-term storage for up to 6 months. In sum, our data demonstrate proper ELISA conditions, allowing the accurate analysis of sAxl levels in human serum.

Analysis of a dynamic model of guard cell signaling reveals the stability of signal propagation

NASA Astrophysics Data System (ADS)

Gan, Xiao; Albert, RéKa

Analyzing the long-term behaviors (attractors) of dynamic models of biological systems can provide valuable insight into biological phenotypes and their stability. We identified the long-term behaviors of a multi-level, 70-node discrete dynamic model of the stomatal opening process in plants. We reduce the model's huge state space by reducing unregulated nodes and simple mediator nodes, and by simplifying the regulatory functions of selected nodes while keeping the model consistent with experimental observations. We perform attractor analysis on the resulting 32-node reduced model by two methods: 1. converting it into a Boolean model, then applying two attractor-finding algorithms; 2. theoretical analysis of the regulatory functions. We conclude that all nodes except two in the reduced model have a single attractor; and only two nodes can admit oscillations. The multistability or oscillations do not affect the stomatal opening level in any situation. This conclusion applies to the original model as well in all the biologically meaningful cases. We further demonstrate the robustness of signal propagation by showing that a large percentage of single-node knockouts does not affect the stomatal opening level. Thus, we conclude that the complex structure of this signal transduction network provides multiple information propagation pathways while not allowing extensive multistability or oscillations, resulting in robust signal propagation. Our innovative combination of methods offers a promising way to analyze multi-level models.

Aspartame-stabilized gold-silver bimetallic biocompatible nanostructures with plasmonic photothermal properties, antibacterial activity, and long-term stability.

PubMed

Fasciani, Chiara; Silvero, M Jazmin; Anghel, Maria Alexandra; Argüello, Gerardo A; Becerra, Maria Cecilia; Scaiano, Juan C

2014-12-17

Gold-silver core-shell nanoparticles stabilized with a common sweetener, aspartame (AuNP@Ag@Asm), combine the antimicrobial properties of silver with the photoinduced plasmon-mediated photothermal effects of gold. The particles were tested with several bacterial strains, while biocompatibility was verified with human dermal fibroblasts.

The lightest organic radical cation for charge storage in redox flow batteries

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

Huang, Jinhua; Pan, Baofei; Duan, Wentao

2016-08-25

Electrochemically reversible fluids of high energy density are promising materials for capturing the electrical energy generated from intermittent sources like solar and wind. To meet this technological challenge there is a need to understand the fundamental limits and interplay of electrochemical potential, stability and solubility in “lean” derivatives of redox-active molecules. Here we describe the process of molecular pruning, illustrated for 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene, a molecule known to produce a persistently stable, high-potential radical cation. By systematically shedding molecular fragments considered important for radical cation steric stabilization, we discovered a minimalistic structure that retains long-term stability in its oxidized form. Interestingly, wemore » find the tert-butyl groups are unnecessary; high stability of the radical cation and high solubility are both realized in derivatives having appropriately positioned arene methyl groups. These stability trends are rationalized by mechanistic considerations of the postulated decomposition pathways. We suggest that the molecular pruning approach will uncover lean redox active derivatives for electrochemical energy storage leading to materials with long-term stability and high intrinsic capacity.« less

Long-term memory, neurogenesis, and signal novelty.

PubMed

Sokolov, E N; Nezlina, N I

2004-10-01

According to our suggested hypothesis, long-term memory is a collection of "gnostic units," selectively tuned to past events. The formation of long-term memory occurs with the involvement of constantly appearing new neurons which differentiate from stem cells during the process of neurogenesis, in particular in adults. Conversion of precursor neurons into "gnostic units" selective in relation to ongoing events, supplemented by the involvement of hippocampal "novelty neurons," which increase the flow of information needing to be fixed in long-term memory. "Gnostic units" form before the informational processes occurring in the ventral ("what?") and dorsal ("where?") systems. Formation of new "gnostic units" selectively tuned to a particular event results from the combination of excitation of the detector for stimulus characteristics and the novelty signal generated by "novelty neurons" in the hippocampus.

The long-term hydrological effect of forest stands on the stability of slopes

NASA Astrophysics Data System (ADS)

Bogaard, T. A.; Meng, W.; van Beek, L. P. H.

2012-04-01

Forest is widely known to improve slope stability as a result of mechanical and hydrological effects. While the mechanics underlying the stabilizing process of root reinforcement are well understood and quantified, the influence of forest on the occurrence of critical hydrological conditions in terms of suction or pore pressure remains uncertain. Due to seasonal and inter-annual fluctuations, the stabilizing influence of evaporation and transpiration is difficult to isolate from the overall noise of the hydrological signal. More long-term effects of forest stands on soil development are highly variable and thus difficult to observe and quantify. Often these effects are ambivalent, having potentially a stabilizing or destabilizing influence on a slope under particular conditions (e.g., more structured soils leading to both rapid infiltration and drainage). Consequently, it can be postulated that forests will hydrologically influence the magnitude-frequency distribution of landsliding, not only at the stand level but also on a regional scale through the groundwater system. The overall aim of this research is to understand and quantify the stabilizing hydrological effect of forests on potentially unstable slopes. To this end, we focus on the changes in the magnitude-frequency distribution of landsliding that arise as a result of variations in evapotranspiration losses over the life cycle of stands. Temporal variations in evapotranspiration comprise first of all the interception that can account for an important amount of evaporation from a forest, and that changes with seasonal and annual variations in the interception capacity of the canopy and forest floor. Transpiration also represents an important loss that varies over the various growth stages of a forest stand. Based on a literature review of water consumption by tree species and water balance studies of forested catchments we defined the potential transpiration for different growth stages. This information we used in a spatially distributed, physical-based, dynamical model to simulate the hydrology and resulting stability for a catchment on a daily scale. The results can be used to identify end members of the hydrological influence of forests on slope stability and the typical variations in stability associated with the various growth stages. They indicate that the influence of forest stand age on the water consumption can be significant and has clear consequences for the antecedent soil moisture condition within a slope and thus on the potential for slope destabilization. The outcome should help to understand the long-term impact of vegetation on slope hydrology and define sustainable and reliable management strategies at the scale of forest stands. Keywords: slope stability, hydrology, vegetation, long-tem effect

SiC/Mg multilayer coatings for SCORE coronagraph: long term stability analysis

NASA Astrophysics Data System (ADS)

Pelizzo, Maria Guglielmina; Fineschi, Silvano; Zuppella, Paola; Corso, Alain Jody; Windt, David L.; Nicolosi, Piergiorgio

2011-10-01

SiC/Mg multilayers have been used as coatings of the Sounding-rocket CORonagraphic Experiment (SCORE) telescope mirrors launched during the NASA HERSCHEL program. This materials couple has been largely studied by researchers since it provides higher performances than a standard Mo/Si multilayer; the SCORE mirrors show in fact a peak reflectance of around 40% at HeII 30.4 nm. Nevertheless, long term stability of this coating is an open problem. A study on the aging and stability of this multilayer has been carried on. SiC/Mg multilayer samples characterized by different structural parameters have been deposited. They have been measured just after deposition and four years later to verify degradation based on natural aging. Experimental results and analysis are presented.

Rapid Recovery of Clofazimine-Loaded Nanoparticles with Long-Term Storage Stability as Anti-Cryptosporidium Therapy.

PubMed

Feng, Jie; Zhang, Yingyue; McManus, Simon A; Ristroph, Kurt D; Lu, Hoang D; Gong, Kai; White, Claire E; Prud'homme, Robert K

2018-05-25

While the formulation of nanoparticle (NP) suspensions has been widely applied in materials and life science, the recovery of NPs from such a suspension into a solid state is practically important to confer long-term storage stability. However, solidification, while preserving the original nanoscale properties, remains a formidable challenge in the pharmaceutical and biomedical applications of NPs. Herein we combined flash nanoprecipitation (FNP) and spray-drying as a nanofabrication platform for NP formulation and recovery without compromising the dissolution kinetics of the active ingredient. Clofazimine was chosen to be the representative drug, which has been recently repurposed as a potential treatment for cryptosporidiosis. Clofazimine was encapsulated in NPs with low-cost surface coatings, hypromellose acetate succinate (HPMCAS) and lecithin, which were required by the ultimate application to global health. Spray-drying and lyophilization were utilized to produce dried powders with good long-term storage stability for application in hot and humid climatic zones. The particle morphology, yield efficiency, drug loading, and clofazimine crystallinity in the spray-dried powders were characterized. The in vitro release kinetics of spray-dried NP powders were compared to analogous dissolution profiles from standard lyophilized NP samples, crystalline clofazimine powder, and the commercially available formulation Lamprene. The spray-dried powders showed a supersaturation level of up to 60 times the equilibrium solubility and remarkably improved dissolution rates. In addition, the spray-dried powders with both surface coatings showed excellent stability during aging studies with elevated temperature and humidity, in view of the dissolution and release in vitro. Considering oral delivery for pediatric administration, the spray-dried powders show less staining effects with simulated skin than crystalline clofazimine and may be made into minitablets without additional excipients. These results highlight the potential of combining FNP and spray-drying as a feasible and versatile platform to design and rapidly recover amorphous NPs in a solid dosage form, with the advantages of satisfactory long-term storage stability, low cost, and easy scalability.

Use of inexpensive vegetable oils to ensure the long-term stability of sweet sorghum syrups for the manufacture of bioproducts

USDA-ARS?s Scientific Manuscript database

Fundamental processing needs identified by industry for the large-scale manufacture of biofuels and bioproducts from sweet sorghum (Sorghum bicolor L. Moench), include the long-term storage of 65 Brix syrups for year-round supply, efficient transport, and acceptable end-product yields. Sweet sorghu...

Long-term tillage and cropping effects on biological properties associated with soil aggregation in semi-arid eastern Montana, USA

USDA-ARS?s Scientific Manuscript database

Long-term tillage and cropping may influence biological attributes responsible for semi-arid soil aggregation in Montana, USA. Aggregate stability, glomalin, basidiomycete fungi, uronic acids, total organic C (TOC) and total N (TN) at 0-5 cm soil depth from 1991 to 2003 were evaluated in different a...

Long-term N fertilization and conservation tillage practices conserve surface but not profile SOC stocks under semi-arid irrigated corn

USDA-ARS?s Scientific Manuscript database

No tillage (NT) and N fertilization can increase surface soil organic C (SOC) stocks, but the effects deeper in the soil profile are uncertain. Subsequent tillage could counter SOC stabilized through NT practices by disrupting soil aggregation and promoting decomposition. We followed a long-term ti...

The Incidence of Adjacent Segment Degeneration after the Use of a Versatile Dynamic Hybrid Stabilization Device in Lumbar Stenosis: Results of a 5–8-Year Follow-up

PubMed Central

Dobran, Mauro; Esposito, Domenico Paolo; Gladi, Maurizio; Scerrati, Massimo; Iacoangeli, Maurizio

2018-01-01

Study Design Retrospective study with long-term follow-up. Purpose To evaluate the long-term incidence of adjacent segment degeneration (ASD) and clinical outcomes in a consecutive series of patients who underwent spinal decompression associated with dynamic or hybrid stabilization with a Flex+TM stabilization system (SpineVision, Antony, France) for lumbar spinal stenosis. Overview of Literature The incidence of ASD and clinical outcomes following dynamic or hybrid stabilization with the Flex+TM system used for lumbar spinal stenosis have not been well investigated. Methods Twenty-one patients with lumbar stenosis and probable post-decompressive spinal instability underwent decompressive laminectomy followed by spinal stabilization using the Flex+TM stabilization system. The indication for a mono-level dynamic stabilization was a preoperative magnetic resonance imaging (MRI) demonstrating evidence of severe disc disease associated with severe spinal stenosis. The hybrid stabilization (rigid-dynamic) system was used for multilevel laminectomies with associated initial degenerative scoliosis, first-grade spondylolisthesis, or rostral pathology. Results The improvement in Visual Analog Scale and Oswestry Disability Index scores at follow-up were statistically significant (p<0.0001 and p<0.0001, respectively). At the 5–8-year follow-up, clinical examination, MRI, and X-ray findings showed an ASD complication with pain and disability in one of 21 patients. The clinical outcomes were similar in patients treated with dynamic or hybrid fixation. Conclusions Patients treated with laminectomy and Flex+TM stabilization presented a satisfactory clinical outcome after 5–8 years of follow-up, and ASD incidence in our series was 4.76% (one patient out of 21). We are aware that this is a small series, but our long-term follow-up may be sufficient to contribute to the expanding body of literature on the development of symptomatic ASD associated with dynamic or hybrid fixation. PMID:29713407

Characterization of highly concentrated antibody solution - A toolbox for the description of protein long-term solution stability

PubMed Central

Schermeyer, Marie-Therese; Wöll, Anna K.; Eppink, Michel; Hubbuch, Jürgen

2017-01-01

ABSTRACT High protein titers are gaining importance in biopharmaceutical industry. A major challenge in the development of highly concentrated mAb solutions is their long-term stability and often incalculable viscosity. The complexity of the molecule itself, as well as the various molecular interactions, make it difficult to describe their solution behavior. To study the formulation stability, long- and short-range interactions and the formation of complex network structures have to be taken into account. For a better understanding of highly concentrated solutions, we combined established and novel analytical tools to characterize the effect of solution properties on the stability of highly concentrated mAb formulations. In this study, monoclonal antibody solutions in a concentration range of 50–200 mg/ml at pH 5–9 with and without glycine, PEG4000, and Na2SO4 were analyzed. To determine the monomer content, analytical size-exclusion chromatography runs were performed. ζ-potential measurements were conducted to analyze the electrophoretic properties in different solutions. The melting and aggregation temperatures were determined with the help of fluorescence and static light scattering measurements. Additionally, rheological measurements were conducted to study the solution viscosity and viscoelastic behavior of the mAb solutions. The so-determined analytical parameters were scored and merged in an analytical toolbox. The resulting scoring was then successfully correlated with long-term storage (40 d of incubation) experiments. Our results indicate that the sensitivity of complex rheological measurements, in combination with the applied techniques, allows reliable statements to be made with respect to the effect of solution properties, such as protein concentration, ionic strength, and pH shift, on the strength of protein-protein interaction and solution colloidal stability. PMID:28617076

Trait-specific long-term consequences of genomic selection in beef cattle.

PubMed

de Rezende Neves, Haroldo Henrique; Carvalheiro, Roberto; de Queiroz, Sandra Aidar

2018-02-01

Simulation studies allow addressing consequences of selection schemes, helping to identify effective strategies to enable genetic gain and maintain genetic diversity. The aim of this study was to evaluate the long-term impact of genomic selection (GS) in genetic progress and genetic diversity of beef cattle. Forward-in-time simulation generated a population with pattern of linkage disequilibrium close to that previously reported for real beef cattle populations. Different scenarios of GS and traditional pedigree-based BLUP (PBLUP) selection were simulated for 15 generations, mimicking selection for female reproduction and meat quality. For GS scenarios, an alternative selection criterion was simulated (wGBLUP), intended to enhance long-term gains by attributing more weight to favorable alleles with low frequency. GS allowed genetic progress up to 40% greater than PBLUP, for female reproduction and meat quality. The alternative criterion wGBLUP did not increase long-term response, although allowed reducing inbreeding rates and loss of favorable alleles. The results suggest that GS outperforms PBLUP when the selected trait is under less polygenic background and that attributing more weight to low-frequency favorable alleles can reduce inbreeding rates and loss of favorable alleles in GS.

Long time stability of lamps with nanostructural carbon field emission cathodes

NASA Astrophysics Data System (ADS)

Kalenik, J.; Firek, P.; Szmidt, J.; Czerwosz, E.; Kozłowski, M.; Stepińska, I.; Wódka, T.

2017-08-01

A luminescent lamp with field emission cathode was constructed and tested. Phosphor excited by electrons from field emission cathode is the source of light. The cathode is covered with nickel-carbon film containing multilayer carbon nanotubes that enhance electron emission from the cathode. Results of luminance stability measurements are presented. Luminance of elaborated luminance lamp is high enough for lighting application. Long term stability (1000 hours) is satisfactory for mass lamp application. Initial short time decrease of luminance is still too high and it needs reduction.

Long-term selection strategies for complex traits using high-density genetic markers.

PubMed

Kemper, K E; Bowman, P J; Pryce, J E; Hayes, B J; Goddard, M E

2012-08-01

Selection of animals for breeding ranked on estimated breeding value maximizes genetic gain in the next generation but does not necessarily maximize long-term response. An alternative method, as practiced by plant breeders, is to build a desired genotype by selection on specific loci. Maximal long-term response in animal breeding requires selection on estimated breeding values with constraints on coancestry. In this paper, we compared long-term genetic response using either a genotype building or a genomic estimated breeding value (GEBV) strategy for the Australian Selection Index (ASI), a measure of profit. First, we used real marker effects from the Australian Dairy Herd Improvement Scheme to estimate breeding values for chromosome segments (approximately 25 cM long) for 2,650 Holstein bulls. Second, we selected 16 animals to be founders for a simulated breeding program where, between them, founders contain the best possible combination of 2 segments from 2 animals at each position in the genome. Third, we mated founder animals and their descendants over 30 generations with 2 breeding objectives: (1) to create a population with the "ideal genotype," where the best 2 segments from the founders segregate at each position, or (2) obtain the highest possible response in ASI with coancestry lower than that achieved under breeding objective 1. Results show that genotype building achieved the ideal genotype for breeding objective 1 and obtained a large gain in ASI over the current population (+A$864.99). However, selection on overall GEBV had greater short-term response and almost as much long-term gain (+A$820.42). When coancestry was lowered under breeding objective 2, selection on overall GEBV achieved a higher response in ASI than the genotype building strategy. Selection on overall GEBV seems more flexible in its selection decisions and was therefore better able to precisely control coancestry while maximizing ASI. We conclude that selection on overall GEBV while minimizing average coancestry is the more practical strategy for dairy cattle where selection is for highly polygenic traits, the reproductive rate is relatively low, and there is low tolerance of coancestry. The outcome may be different for traits controlled by few loci of relatively large effects or for different species. In contrast to other simulations, our results indicate that response to selection on overall GEBV may continue for several generations. This is because long-term genetic change in complex traits requires favorable changes to allele frequencies for many loci located throughout the genome. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

2004-01-01

Advanced thermal and environmental barrier coatings (TEBCs) 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 advanced 1650 C TEBC system is required to have a better high-temperature stability, lower thermal conductivity, and more resistance to sintering and thermal stress than current coating systems under engine high-heat-flux and severe thermal cycling conditions. In this report, the thermal conductivity and water vapor stability of selected candidate hafnia-, pyrochlore- and magnetoplumbite-based TEBC materials are evaluated. The effects of dopants on the materials properties are also discussed. The test results have been used to downselect the TEBC materials and help demonstrate the feasibility of advanced 1650 C coatings with long-term thermal cycling durability.

Effect of microemulsions on cell viability of human dermal fibroblasts

NASA Astrophysics Data System (ADS)

Li, Juyi; Mironava, Tatsiana; Simon, Marcia; Rafailovich, Miriam; Garti, Nissim

Microemulsions are optically clear, thermostable and isotropic mixture consisting of water, oil and surfactants. Their advantages of ease preparation, spontaneous formation, long-term stability and enhanced solubility of bioactive materials make them great potentials as vehicles in food and pharmaceutical applications. In this study, comparative in vitro cytotoxicity tests were performed to select a best formulation of microemulsion with the least toxicity for human dermal fibroblasts. Three different kinds of oils and six different kinds of surfactants were used to form microemulsions by different ratios. The effect of oil type and surfactant type as well as their proportions on cell proliferation and viability were tested.

Optical fiber Fabry-Perot interferometry

NASA Astrophysics Data System (ADS)

Wang, Anbo

2014-06-01

Fiber Fabry-Perot (FP) interferometry is one of the most important tools for harsh environment sensing because of its great flexibility of sensor material selection, superior long-­-term stability, and nature of remote passive operation. Virginia Tech's Center for Photonics Technology has been involved in the research of this field for many years. After a quick review of the typical methods for the construction of F-P sensors, emphasis will be placed on the whitelight interferometry, which is perhaps the most robust interferometric sensor demodulation technique today. The recent discovery of an additional phase will be presented and its significance to the sensor demodulation will be discussed.

Routine low-level monitoring of polar pesticides and pesticide degradates by HPLC/ESI-MS: Evaluating long-term performance

USGS Publications Warehouse

Furlong, E.T.; Martin, Jeffrey D.; Werner, S.L.; Gates, Paul M.

2002-01-01

The sensitivity and selective determination of polar pesticides were analyzed using high-performance liquid chromatography/electrospray ionization-mass spectrometry (HPLC/ESI-MS). The effects of multiple operators and instruments on method performance were evaluated using 440 pairs of fortified reagent-water and blank reagent-water samples. The influence of varying environmental matrices on recovery and precision were also analyzed using 200 fortified ambient water samples and duplicate ambient water samples. The results show that compound stability in filtered water was matrix-, chemical class- and compound-dependent which ranged from 1 day to 2 weeks.

Zairian Political Conditions and Prospects for Economic Development,

DTIC Science & Technology

1984-08-15

political conditions and potential for long-term economic development. Two different approaches to the question of political stability and economic...development are presented. Each assumes that political stability is a necessary, though not sufficient, condition for economic development and that, therefore

"Long-term stability of stimulating spiral nerve cuff electrodes on human peripheral nerves".

PubMed

Christie, Breanne P; Freeberg, Max; Memberg, William D; Pinault, Gilles J C; Hoyen, Harry A; Tyler, Dustin J; Triolo, Ronald J

2017-07-11

Electrical stimulation of the peripheral nerves has been shown to be effective in restoring sensory and motor functions in the lower and upper extremities. This neural stimulation can be applied via non-penetrating spiral nerve cuff electrodes, though minimal information has been published regarding their long-term performance for multiple years after implantation. Since 2005, 14 human volunteers with cervical or thoracic spinal cord injuries, or upper limb amputation, were chronically implanted with a total of 50 spiral nerve cuff electrodes on 10 different nerves (mean time post-implant 6.7 ± 3.1 years). The primary outcome measures utilized in this study were muscle recruitment curves, charge thresholds, and percent overlap of recruited motor unit populations. In the eight recipients still actively involved in research studies, 44/45 of the spiral contacts were still functional. In four participants regularly studied over the course of 1 month to 10.4 years, the charge thresholds of the majority of individual contacts remained stable over time. The four participants with spiral cuffs on their femoral nerves were all able to generate sufficient moment to keep the knees locked during standing after 2-4.5 years. The dorsiflexion moment produced by all four fibular nerve cuffs in the active participants exceeded the value required to prevent foot drop, but no tibial nerve cuffs were able to meet the plantarflexion moment that occurs during push-off at a normal walking speed. The selectivity of two multi-contact spiral cuffs was examined and both were still highly selective for different motor unit populations for up to 6.3 years after implantation. The spiral nerve cuffs examined remain functional in motor and sensory neuroprostheses for 2-11 years after implantation. They exhibit stable charge thresholds, clinically relevant recruitment properties, and functional muscle selectivity. Non-penetrating spiral nerve cuff electrodes appear to be a suitable option for long-term clinical use on human peripheral nerves in implanted neuroprostheses.

24 CFR 578.37 - Program components and uses of assistance.

Code of Federal Regulations, 2013 CFR

2013-04-01

...-term (up to 3 months) and/or medium-term (for 3 to 24 months) tenant-based rental assistance, as set... providing short-term and/or medium-term rental assistance to program participants, the rental assistance is... ensuring long-term housing stability. The project is exempt from this requirement if the Violence Against...

24 CFR 578.37 - Program components and uses of assistance.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-term (up to 3 months) and/or medium-term (for 3 to 24 months) tenant-based rental assistance, as set... providing short-term and/or medium-term rental assistance to program participants, the rental assistance is... ensuring long-term housing stability. The project is exempt from this requirement if the Violence Against...

Long-term stability of morphine, codeine, and 6-acetylmorphine in real-life whole blood samples, stored at -20°C.

PubMed

Høiseth, Gudrun; Fjeld, Bente; Burns, Margrete Larsen; Strand, Dag Helge; Vindenes, Vigdis

2014-06-01

Stability of drugs during storage is important in forensic toxicology. For the analytes detected after intake of heroin (6-acetylmorphine (6-AM), morphine and codeine), long-time stability in real life whole blood samples are studied in only a small number of cases. Whole blood post mortem (n=37) and whole blood samples from living persons (n=22) containing morphine and codeine as well as 6-AM in blood or urine were selected. All cases represented intake of heroin. All samples contained fluoride and were initially analysed and stored in normal conditions (-20°C) for 4-9 years. All samples were then reanalysed using the same analytical methods and the results were compared. For samples from living persons, the median change in concentration was -3.7% for morphine and -5.3% for codeine. For post mortem samples, the median change in concentration was -12% for morphine and -11% for codeine. Both for samples from living persons and post mortem samples, the decrease in the concentrations from the original analysis to reanalysis were statistically significant for morphine and codeine. Regarding 6-AM, all living samples were negative at reanalysis. For post mortem samples, four cases still tested positive for 6-AM at reanalysis with a median change in the concentrations of -81%. There was no significant change in the morphine to codeine concentration ratios neither for living nor post mortem samples. This study showed that in real life whole blood samples, the concentrations of morphine and codeine are relatively stable during long-term storage at -20°C. 6-AM on the other hand, shows a considerable decrease in concentrations that is important to consider when interpreting results from reanalyses of forensic cases. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Long-term no-tillage and organic input management enhanced the diversity and stability of soil microbial community.

PubMed

Wang, Yi; Li, Chunyue; Tu, Cong; Hoyt, Greg D; DeForest, Jared L; Hu, Shuijin

2017-12-31

Intensive tillage and high inputs of chemicals are frequently used in conventional agriculture management, which critically depresses soil properties and causes soil erosion and nonpoint source pollution. Conservation practices, such as no-tillage and organic farming, have potential to enhance soil health. However, the long-term impact of no-tillage and organic practices on soil microbial diversity and community structure has not been fully understood, particularly in humid, warm climate regions such as the southeast USA. We hypothesized that organic inputs will lead to greater microbial diversity and a more stable microbial community, and that the combination of no-tillage and organic inputs will maximize soil microbial diversity. We conducted a long-term experiment in the southern Appalachian mountains of North Carolina, USA to test these hypotheses. The results showed that soil microbial diversity and community structure diverged under different management regimes after long term continuous treatments. Organic input dominated the effect of management practices on soil microbial properties, although no-tillage practice also exerted significant impacts. Both no-tillage and organic inputs significantly promoted soil microbial diversity and community stability. The combination of no-tillage and organic management increased soil microbial diversity over the conventional tillage and led to a microbial community structure more similar to the one in an adjacent grassland. These results indicate that effective management through reducing tillage and increasing organic C inputs can enhance soil microbial diversity and community stability. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of long-term cryopreservation on peripheral blood progenitor cells.

PubMed

Vosganian, Gregory S; Waalen, Jill; Kim, Kevin; Jhatakia, Sejal; Schram, Ethan; Lee, Tracey; Riddell, Dan; Mason, James R

2012-11-01

The long-term stability of cryopreserved peripheral blood progenitor cells is an important issue for patients experiencing disease relapse. However, there is no consensus on how to evaluate the long-term effects of cryopreservation. We describe the effect of cryopreservation on viability and progenitor colony activity from 87 individual samples processed at the Scripps Green Hospital Stem Cell Processing Center (La Jolla, CA, USA). We randomly selected 87 peripheral blood hematopoietic stem cell (PBHSC) samples from 60 patients and evaluated the effect of cryopreservation on sample viability and red and white cell colony activity after < 24 h and 7, 10 and 15 years of cryopreservation. Viability was assayed via trypan blue dye exclusion and activity was measured following 14 days of culture. An age at collection older than 50 years may result in suboptimal activity and viability following long-term cryopreservation, while gender and disease status had no effect. Cryopreservation did not significantly affect white or red cell activity following 10 years of cryopreservation. However, for samples stored longer than 10 years, viability and activity significantly decreased. We noted a positive association between higher pre-cryopreservation %CD34 count and colony activity. Cryopreservation of peripheral blood progenitor cells for up to 10 years results in no loss of clonogenic capacity, as determined by culture activity, although longer durations of storage may affect activity. Until validated methods are developed, cryopreserved grafts should be evaluated based on pre-freeze CD34(+) cell counts as assayed by flow cytometry, and post-thaw sample evaluation should be reserved for patients identified as poor mobilizers.

ISS Contingency Attitude Control Recovery Method for Loss of Automatic Thruster Control

NASA Technical Reports Server (NTRS)

Bedrossian, Nazareth; Bhatt, Sagar; Alaniz, Abran; McCants, Edward; Nguyen, Louis; Chamitoff, Greg

2008-01-01

In this paper, the attitude control issues associated with International Space Station (ISS) loss of automatic thruster control capability are discussed and methods for attitude control recovery are presented. This scenario was experienced recently during Shuttle mission STS-117 and ISS Stage 13A in June 2007 when the Russian GN&C computers, which command the ISS thrusters, failed. Without automatic propulsive attitude control, the ISS would not be able to regain attitude control after the Orbiter undocked. The core issues associated with recovering long-term attitude control using CMGs are described as well as the systems engineering analysis to identify recovery options. It is shown that the recovery method can be separated into a procedure for rate damping to a safe harbor gravity gradient stable orientation and a capability to maneuver the vehicle to the necessary initial conditions for long term attitude hold. A manual control option using Soyuz and Progress vehicle thrusters is investigated for rate damping and maneuvers. The issues with implementing such an option are presented and the key issue of closed-loop stability is addressed. A new non-propulsive alternative to thruster control, Zero Propellant Maneuver (ZPM) attitude control method is introduced and its rate damping and maneuver performance evaluated. It is shown that ZPM can meet the tight attitude and rate error tolerances needed for long term attitude control. A combination of manual thruster rate damping to a safe harbor attitude followed by a ZPM to Stage long term attitude control orientation was selected by the Anomaly Resolution Team as the alternate attitude control method for such a contingency.

Microbial community controls on decomposition and soil carbon storage

NASA Astrophysics Data System (ADS)

Frey, S. D.

2016-12-01

Soil is one of the most diverse habitats on Earth and one of the least characterized in terms of the identification and ecological roles of soil organisms. Soils also contain the largest repository of organic C in the terrestrial biosphere and the activities of heterotrophic soil organisms are responsible for one of the largest annual fluxes of CO2 to the atmosphere. A fundamental controversy in ecosystem ecology is the degree to which identification of microbial taxa informs our ability to understand and model ecosystem-scale processes, such as soil carbon storage and fluxes. We have evidence that microbial identity does matter, particularly in a global change context where soil microorganisms experience selective pressures to adapt to changing environments. In particular, our work at the Harvard Forest Long-term Ecological Research (LTER) site demonstrates that the microbial community is fundamentally altered by global change stressors (climate warming, nitrogen deposition, biotic invasion) and that microbial taxa exposed to long-term environmental change exhibit an altered capacity to decompose organic matter. This talk will discuss the relative importance of changes in microbial community structure versus microbial physiology for soil organic matter degradation and stabilization.

Nanoparticles in Medicine: Selected Observations and Experimental Caveats.

PubMed

Thomsen, Sharon; Pearce, John A; Giustini, Andrew; Hoopes, P Jack

2013-02-26

Medically useful nanoparticles measure 1-100 nm in at least one dimension and are engineered and manufactured for specific diagnostic and treatment applications. Most nanoparticles used currently used in medicine are engineered and manufactured for specific purposes. Medically significant nanoparticles are composed of a 1) central core that is usually the medically active component, 2) one or more layers of organic or inorganic materials that forms a capsule (corona) covering the core and 3) an outer surface layer that interacts with the environment and/or targeted cells and tissues. Effective nanoparticle function in the living, intact animal or human requires electrochemical stability necessary to bypass the reticuloendothelial system (RES) and avoid filtration through the renal glomerulus into the urine. Nanoparticles are present in "natural" as well as the manufacturing and clinical environments thus could pose as significant toxins because of their small sizes, their chemical and drug content and potential effect of causing long term disease including allergies, chronic inflammation and cancer. Currently published studies have focused on the effects of nanoparticles on cells in the extremely artificial environments of cell cultures. More clinical and preclinical studies documenting the short term and long term effects nanoparticle in the intact experimental animal and human are needed.

Nanoparticles in medicine: selected observations and experimental caveats

NASA Astrophysics Data System (ADS)

Thomsen, Sharon; Pearce, John A.; Giustini, Andrew; Hoopes, P. Jack

2013-02-01

Medically useful nanoparticles measure 1-100 nm in at least one dimension and are engineered and manufactured for specific diagnostic and treatment applications. Most nanoparticles used currently used in medicine are engineered and manufactured for specific purposes. Medically significant nanoparticles are composed of a 1) central core that is usually the medically active component, 2) one or more layers of organic or inorganic materials that forms a capsule (corona) covering the core and 3) an outer surface layer that interacts with the environment and/or targeted cells and tissues. Effective nanoparticle function in the living, intact animal or human requires electrochemical stability necessary to bypass the reticuloendothelial system (RES) and avoid filtration through the renal glomerulus into the urine. Nanoparticles are present in " natural" as well as the manufacturing and clinical environments thus could pose as significant toxins because of their small sizes, their chemical and drug content and potential effect of causing long term disease including allergies, chronic inflammation and cancer. Currently published studies have focused on the effects of nanoparticles on cells in the extremely artificial environments of cell cultures. More clinical and preclinical studies documenting the short term and long term effects nanoparticle in the intact experimental animal and human are needed.

Rapamycin inhibits mTOR/p70S6K activation in CA3 region of the hippocampus of the rat and impairs long term memory.

PubMed

Lana, D; Di Russo, J; Mello, T; Wenk, G L; Giovannini, M G

2017-01-01

The present study was aimed at establishing whether the mTOR pathway and its downstream effector p70S6K in CA3 pyramidal neurons are under the modulation of the cholinergic input to trigger the formation of long term memories, similar to what we demonstrated in CA1 hippocampus. We performed in vivo behavioral experiments using the step down inhibitory avoidance test in adult Wistar rats to evaluate memory formation under different conditions. We examined the effects of rapamycin, an inhibitor of mTORC1 formation, scopolamine, a muscarinic receptor antagonist or mecamylamine, a nicotinic receptor antagonist, on short and long term memory formation and on the functionality of the mTOR pathway. Acquisition was conducted 30min after i.c.v. injection of rapamycin. Recall testing was performed 1h, 4h or 24h after acquisition. We found that (1) mTOR and p70S6K activation in CA3 pyramidal neurons were involved in long term memory formation; (2) rapamycin significantly inhibited mTOR and of p70S6K activation at 4h, and long term memory impairment 24h after acquisition; (3) scopolamine impaired short but not long term memory, with an early increase of mTOR/p70S6K activation at 1h followed by stabilization at longer times; (4) mecamylamine and scopolamine co-administration impaired short term memory at 1h and 4h and reduced the scopolamine-induced increase of mTOR/p70S6K activation at 1h and 4h; (5) mecamylamine and scopolamine treatment did not impair long term memory formation; (6) unexpectedly, rapamycin increased mTORC2 activation in microglial cells. Our results demonstrate that in CA3 pyramidal neurons the mTOR/p70S6K pathway is under the modulation of the cholinergic system and is involved in long-term memory encoding, and are consistent with the hypothesis that the CA3 region of the hippocampus is involved in memory mechanisms based on rapid, one-trial object-place learning and recall. Furthermore, our results are in accordance with previous reports that selective molecular mechanisms underlie either short term memory, long term memory, or both. Furthermore, our discovery that administration of rapamycin increased the activation of mTORC2 in microglial cells supports a reappraisal of the beneficial/adverse effects of rapamycin administration. Copyright © 2016 Elsevier Inc. All rights reserved.

Rapamycin inhibits mTOR/p70S6K activation in CA3 region of the hippocampus of the rat and impairs long term memory

PubMed Central

Lana, D.; Di Russo, J.; Mello, T.; Wenk, G.L.; Giovannini, M.G.

2016-01-01

The present study was aimed at establishing whether the mTOR pathway and its downstream effector p70S6K in CA3 pyramidal neurons are under the modulation of the cholinergic input to trigger the formation of long term memories, similar to what we demonstrated in CA1 hippocampus. We performed in vivo behavioral experiments using the step down inhibitory avoidance test in adult Wistar rats to evaluate memory formation under different conditions. We examined the effects of rapamycin, an inhibitor of mTORC1 formation, scopolamine, a muscarinic receptor antagonist or mecamylamine, a nicotinic receptor antagonist, on short and long term memory formation and on the functionality of the mTOR pathway. Acquisition was conducted 30 min after i.c.v. injection of rapamycin. Recall testing was performed 1h, 4h or 24h after acquisition. We found that (1) mTOR and p70S6K activation in CA3 pyramidal neurons were involved in long term memory formation; (2) rapamycin significantly inhibited mTOR and of p70S6K activation at 4h, and long term memory impairment 24h after acquisition; (3) scopolamine impaired short but not long term memory, with an early increase of mTOR/p70S6K activation at 1h followed by stabilization at longer times; (4) mecamylamine and scopolamine co-administration impaired short term memory at 1h and 4h and reduced the scopolamine-induced increase of mTOR/p70S6K activation at 1h and 4h; (5) mecamylamine and scopolamine treatment did not impair long term memory formation; (6) unexpectedly, rapamycin increased mTORC2 activation in microglial cells. Our results demonstrate that in CA3 pyramidal neurons the mTOR/p70S6K pathway is under the modulation of the cholinergic system and is involved in long-term memory encoding, and are consistent with the hypothesis that the CA3 region of the hippocampus is involved in memory mechanisms based on rapid, one-trial object–place learning and recall. Furthermore, our results are in accordance with previous reports that selective molecular mechanisms underlie either short term memory, long term memory, or both. Furthermore, our discovery that administration of rapamycin increased the activation of mTORC2 in microglial cells supports a reappraisal of the beneficial/adverse effects of rapamycin administration. PMID:27838442

Pelvic ring injuries: Surgical management and long-term outcomes

PubMed Central

Halawi, Mohamad J.

2016-01-01

Pelvic ring injuries present a therapeutic challenge to the orthopedic surgeon. Management is based on the patient's physiological status, fracture classification, and associated injuries. Surgical stabilization is indicated in unstable injury patterns and those that fail nonsurgical management. The optimal timing for definitive fixation is not clearly defined, but early stabilization is recommended. Surgical techniques include external fixation, open reduction and internal fixation, and minimally invasive percutaneous osteosynthesis. Special considerations are required for concomitant acetabular fractures, sacral fractures, and those occurring in skeletally immature patients. Long-term outcomes are limited by lack of pelvis-specific outcome measures and burden of associated injuries. PMID:26908968

Effects of graphite fiber stability on the properties of PMR polyimide composites

NASA Technical Reports Server (NTRS)

Delvigs, P.; Alston, W. B.; Vannucci, R. D.

1979-01-01

The effect of the stability of graphite fibers on composite properties after exposure in air at 600 F was investigated. Composites were fabricated from PMR-15 and PMR-2 monomer solutions, using HTS-2 and Celion 6000 graphite fibers as the reinforcement. The effect of long-term exposure in air at 600 F on composite weight loss and mechanical properties was determined. These composites exhibited a significantly increased lifetime at that temperature compared to composites fabricated from HTS fiber sold prior to 1975. The effect of the PMR-15 and PMR-II resin compositions on long-term composite performance at 600 F is also discussed.

Satellite Instrument Calibration for Measuring Global Climate Change. Report of a Workshop at the University of Maryland Inn and Conference Center, College Park, MD. , November 12-14, 2002

NASA Technical Reports Server (NTRS)

Ohring, G.; Wielicki, B.; Spencer, R.; Emery, B.; Datla, R.

2004-01-01

Measuring the small changes associated with long-term global climate change from space is a daunting task. To address these problems and recommend directions for improvements in satellite instrument calibration some 75 scientists, including researchers who develop and analyze long-term data sets from satellites, experts in the field of satellite instrument calibration, and physicists working on state of the art calibration sources and standards met November 12 - 14, 2002 and discussed the issues. The workshop defined the absolute accuracies and long-term stabilities of global climate data sets that are needed to detect expected trends, translated these data set accuracies and stabilities to required satellite instrument accuracies and stabilities, and evaluated the ability of current observing systems to meet these requirements. The workshop's recommendations include a set of basic axioms or overarching principles that must guide high quality climate observations in general, and a roadmap for improving satellite instrument characterization, calibration, inter-calibration, and associated activities to meet the challenge of measuring global climate change. It is also recommended that a follow-up workshop be conducted to discuss implementation of the roadmap developed at this workshop.

Three-Dimensional, Inkjet-Printed Organic Transistors and Integrated Circuits with 100% Yield, High Uniformity, and Long-Term Stability.

PubMed

Kwon, Jimin; Takeda, Yasunori; Fukuda, Kenjiro; Cho, Kilwon; Tokito, Shizuo; Jung, Sungjune

2016-11-22

In this paper, we demonstrate three-dimensional (3D) integrated circuits (ICs) based on a 3D complementary organic field-effect transistor (3D-COFET). The transistor-on-transistor structure was achieved by vertically stacking a p-type OFET over an n-type OFET with a shared gate joining the two transistors, effectively halving the footprint of printed transistors. All the functional layers including organic semiconductors, source/drain/gate electrodes, and interconnection paths were fully inkjet-printed except a parylene dielectric which was deposited by chemical vapor deposition. An array of printed 3D-COFETs and their inverter logic gates comprising over 100 transistors showed 100% yield, and the uniformity and long-term stability of the device were also investigated. A full-adder circuit, the most basic computing unit, has been successfully demonstrated using nine NAND gates based on the 3D structure. The present study fulfills the essential requirements for the fabrication of organic printed complex ICs (increased transistor density, 100% yield, high uniformity, and long-term stability), and the findings can be applied to realize more complex digital/analogue ICs and intelligent devices.

Short- and Long-Term Sleep Stability in Insomniacs and Healthy Controls

PubMed Central

Gaines, Jordan; Vgontzas, Alexandros N.; Fernandez-Mendoza, Julio; Basta, Maria; Pejovic, Slobodanka; He, Fan; Bixler, Edward O.

2015-01-01

Study Objectives: Assess the short- and long-term stability of sleep duration in patients with insomnia and normal-sleeping controls. Design: Observational short-term and prospective studies. Setting: Sleep laboratory. Participants: Patients with insomnia (n = 150) and controls (n = 151) were recruited from the local community or sleep disorders clinic. A subsample of 95 men from the Penn State Adult Cohort (PSAC) were followed up 2.6 y after their initial visit. Measurements: Participants underwent a physical examination and 8-h polysomnography (PSG) recording for 3 consecutive nights (controls and insomniacs), or 2 single nights separated by several years (PSAC). Intraclass correlation coefficients (ICCs) assessed the stability of the variables total sleep time (TST), sleep onset latency (SOL), and wake after sleep onset (WASO). We also examined persistence of the first-night classification of “short” versus “normal” sleep duration on subsequent nights. Results: Stability of TST, SOL, and WASO based on 1 night were slight to moderate in both patients with insomnia (ICC = 0.37–0.57) and controls (ICC = 0.39–0.59), and became substantial to almost perfect when based on the average of 3 nights (ICC = 0.64–0.81). We observed similar degrees of stability for TST and WASO in the longitudinal sample, with moderate stability based on a single night and substantial stability based on both nights. In examining the persistence of “short” and “normal” sleep duration, 71.4% (controls), 74.7% (patients with insomnia), and 72.6% (longitudinal sample) of participants retained their first-night classifications over subsequent nights. Conclusions: Sleep duration variables, particularly total sleep time based on 3 consecutive nights in both patients with insomnia and controls or two single-night recordings separated by several years, are stable and reflect a person's habitual sleep. Furthermore, a single night in the laboratory may be useful for reliably classifying one's sleep duration. Citation: Gaines J, Vgontzas AN, Fernandez-Mendoza J, Basta M, Pejovic S, He F, Bixler EO. Short- and long-term sleep stability in insomniacs and healthy controls. SLEEP 2015;38(11):1727–1734. PMID:26237768

Genetic analyses of Per.C6 cell clones producing a therapeutic monoclonal antibody regarding productivity and long-term stability.

PubMed

Tsuruta, Lilian Rumi; Lopes Dos Santos, Mariana; Yeda, Fernanda Perez; Okamoto, Oswaldo Keith; Moro, Ana Maria

2016-12-01

Genetic characterization of protein-producing clones represents additional value to cell line development. In the present study, ten Per.C6 clones producing a Rebmab100 monoclonal antibody were selected using two cloning methods: six clones originated from limiting dilution cloning and four by the automated colony picker ClonePix FL. A stability program was performed for 50 generations, including 4 batches distributed along the timeframe to determine specific productivity (Qp) maintenance. Four stable clones (two from limiting dilution and two from ClonePix FL) were further evaluated. The relative mRNA expression levels of both heavy chain (HC) and light chain (LC) genes were verified at generations 0, 30-35, and 50-55 of the stability program. At generations 0 and 30-35, LC gene expression level was higher than HC gene, whereas at generation 50-55, the opposite prevailed. A high correlation was observed between Qp and HC or LC mRNA expression level for all clones at each generation analyzed along the continuous culture. The mRNA stability study was performed at steady-state culture. The LC gene displayed a higher half-life and lower decay constant than HC gene, accounting for the higher observed expression level of LC mRNA in comparison to HC mRNA. Clone R6 was highlighted due its high Qp, mRNA expression levels, and mRNA stability. Besides the benefits of applying genetic characterization for the selection of stable and high-producing clones, the present study shows for the first time the correlation between Qp and HC or LC expression levels and also mRNA stability in clones derived from human cell line Per.C6(®).

Islet Transplantation in Type 1 Diabetes: Ongoing Challenges, Refined Procedures, and Long-Term Outcome

PubMed Central

Shapiro, A.M. James

2012-01-01

Remarkable progress has been made in islet transplantation over a span of 40 years. Once just an experimental curiosity in mice, this therapy has moved forward, and can now provide robust therapy for highly selected patients with type 1 diabetes (T1D), refractory to stabilization by other means. This progress could not have occurred without extensive dynamic international collaboration. Currently, 1,085 patients have undergone islet transplantation at 40 international sites since the Edmonton Protocol was reported in 2000 (752 allografts, 333 autografts), according to the Collaborative Islet Transplant Registry. The long-term results of islet transplantation in selected centers now match registry data of pancreas-alone transplantation, with 6 sites reporting five-year insulin independence rates ≥50%. Islet transplantation has been criticized for the use of multiple donor pancreas organs, but progress has also occurred in single-donor success, with 10 sites reporting increased single-donor engraftment. The next wave of innovative clinical trial interventions will address instant blood-mediated inflammatory reaction (IBMIR), apoptosis, and inflammation, and will translate into further marked improvements in single-donor success. Effective control of auto- and alloimmunity is the key to long-term islet function, and high-resolution cellular and antibody-based assays will add considerable precision to this process. Advances in immunosuppression, with new antibody-based targeting of costimulatory blockade and other T-B cellular signaling, will have further profound impact on the safety record of immunotherapy. Clinical trials will move forward shortly to test out new human stem cell derived islets, and in parallel trials will move forward, testing pig islets for compatibility in patients. Induction of immunological tolerance to self-islet antigens and to allografts is a difficult challenge, but potentially within our grasp. PMID:23804275

24 h urinary free cortisol in large-scale epidemiological studies: short-term and long-term stability and sources of variability.

PubMed

Rosmalen, Judith G M; Kema, Ido P; Wüst, Stefan; van der Ley, Claude; Visser, Sipke T; Snieder, Harold; Bakker, Stephan J L

2014-09-01

Function of the hypothalamus-pituitary-adrenal (HPA) axis has been associated with several somatic and psychiatric health problems. The amount of free cortisol excreted in the urine during 24h (24-h UFC) has often been used as a proxy for HPA-axis function. Reference values for 24-h UFC and their stability in the short and long term, as well as sources of variability, are largely lacking. This study was performed in a general population cohort. Participants collected 24-h UFC on two consecutive days (T1), and repeated this collection approximately 2 years later (T2). Cortisol in urine was measured using LC-MS/MS. Height and weight were measured at the research facilities; glomerular filtration rate was estimated using creatinine clearance. Psychological distress (General Health Questionnaire), smoking, alcohol use and exercise were measured by means of questionnaires. 24-h UFC stability on a day-to-day basis was 0.69 (T1, N=1192) and 0.72 (T2, N=963) (both p<0.001). Long-term stability as indicated by correlation between 2-day averages of T1 and T2 was 0.60 (N=972, p<0.001). Multivariable linear regression analysis revealed that 24-h UFC was predicted by urine volume (standardized beta 0.282 (T1, N=1556) and 0.276 (T2, N=1244); both p<0.001) and glomerular filtration rate (standardized beta 0.137 (T1) and 0.179 (T2); both p<0.001), while also sex explained a small part (standardized beta for female sex -0.057 (T1) and -0.080 (T2); both p<0.05). 24-h UFC is moderately stable both in the short and the long term. The effects of urine volume and glomerular filtration rate on 24-h UFC are much stronger than those of sex. Copyright © 2014 Elsevier Ltd. All rights reserved.

Short-term and long-term effects of protein kinase C on the trafficking and stability of human organic anion transporter 3

PubMed Central

Zhang, Qiang; Suh, Wonmo; Pan, Zui; You, Guofeng

2012-01-01

Human organic anion transporter 3 (hOAT3) belongs to a family of organic anion transporters that play critical roles in the body disposition of numerous clinically important drugs. Therefore, understanding the regulation of this transporter has profound clinical significance. In the current study, we investigated the short-term and long-term regulation of hOAT3 by protein kinase C (PKC). We showed that short-term activation of PKC by phobol 12-Myristate 13-Acetate (PMA) inhibited hOAT3 activity through accelerating its internalization from cell surface to intracellular recycling endosomes. The colocalization of hOAT3 with EEA1-positive recycling endosomes was demonstrated by immunolocalization with confocal microscopy. Furthermore, we showed that long-term activation of PKC resulted in the enhanced degradation of cell surface hOAT3. The pathways for hOAT3 degradation were further examined using proteasomal and lysosomal inhibitors. Our results showed that both proteasomal inhibitors and the lysosomal inhibitors significantly blocked hOAT3 degradation. These results demonstrate that PKC plays critical roles in the trafficking and the stability of hOAT3. PMID:22773962

Long-term stability of self-assembled monolayers on 316L stainless steel.

PubMed

Kaufmann, C R; Mani, G; Marton, D; Johnson, D M; Agrawal, C M

2010-04-01

316L stainless steel (316L SS) has been extensively used for making orthopedic, dental and cardiovascular implants. The use of phosphonic acid self-assembled monolayers (SAMs) on 316L SS has been previously explored for potential biomedical applications. In this study, we have investigated the long-term stability of methyl (-CH(3)) and carboxylic acid (-COOH)-terminated phosphonic acid SAMs on 316L under physiological conditions. The stability of SAMs on mechanically polished and electropolished 316L SS was also investigated as a part of this study. Well-ordered and uniform -CH(3)- and -COOH-terminated SAMs were coated on mechanically polished and electropolished 316L SS surfaces. The long-term stability of SAMs on 316L SS was investigated for up to 28 days in Tris-buffered saline (TBS) at 37 degrees C using x-ray photoelectron spectroscopy, atomic force microscopy and contact angle goniometry. A significant amount of phosphonic acid molecules was desorbed from the 316L SS surfaces within 1 to 7 days of TBS immersion followed by a slow desorption of molecules over the remaining days. The -COOH-terminated SAM was found to be more stable than the -CH(3)-terminated SAM on both mechanically and electropolished surfaces. No significant differences in the desorption behavior of SAMs were observed between mechanically and electropolished 316L SS surfaces.

One-step transversal palatal distraction and maxillary repositioning: technical considerations, advantages, and long-term stability.

PubMed

Cortese, Antonio; Savastano, Mauro; Savastano, Germano; Claudio, Pier Paolo

2011-09-01

Transversal maxillary hypoplasia in adolescence is a frequently seen pathology, which can be treated with a combination of surgery and orthodontic treatment to widen the maxilla in skeletally matured patients.We evaluated the advantages of a new surgical technique: Le Fort I distraction osteogenesis using a bone-borne device. Because relapse is one of the main problems in surgical maxillary expansion, long-term stability of this new technique was evaluated. Data from 4 adult patients with maxillary restriction, class III malocclusion, or maxillary malposition were collected preoperatively, 4 months after distraction, and 5 years after distraction. Measurements were recorded on dental models to detect palatal expansion at dental level; cephalograms by lateral and posteroanterior plane were analyzed to detect maxillary movements. Maxillary measurements were substantially stable 5 years after distractions. Only minor dental movements occurred at the dental analysis after 5 years related to a lack of orthodontic contention without any compromise of the dental result (no crossbite relapse and class I stability). Le Fort I with down-fracture for expansion and repositioning by bone-borne distractor device can [corrected] be used to simultaneously widen, advance, and vertically reposition the maxilla without causing healing problems, particularly using a rigid distraction device. Long-term stability can be achieved; however, further studies with a larger number of patients will be necessary for better evaluation.

Optical Stabilization of a Microwave Oscillator for Fountain Clock Interrogation.

PubMed

Lipphardt, Burghard; Gerginov, Vladislav; Weyers, Stefan

2017-04-01

We describe an optical frequency stabilization scheme of a microwave oscillator that is used for the interrogation of primary cesium fountain clocks. Because of its superior phase noise properties, this scheme, which is based on an ultrastable laser and a femtosecond laser frequency comb, overcomes the frequency instability limitations of fountain clocks given by the previously utilized quartz-oscillator-based frequency synthesis. The presented scheme combines the transfer of the short-term frequency instability of an optical cavity and the long-term frequency instability of a hydrogen maser to the microwave oscillator and is designed to provide continuous long-term operation for extended measurement periods of several weeks. The utilization of the twofold stabilization scheme on the one hand ensures the referencing of the fountain frequency to the hydrogen maser frequency and on the other hand results in a phase noise level of the fountain interrogation signal, which enables fountain frequency instabilities at the 2.5 ×10 -14 (τ/s) -1/2 level that are quantum projection noise limited.

Long-Term Stability of Spaceflight Food for Multi-Year Exploration Missions

NASA Astrophysics Data System (ADS)

Douglas, G. L.; Barr, Y. R.

2018-02-01

Stability of macro- and micro-nutrients and undesirable changes to texture and taste will be evaluated in food samples returned from the Deep Space Gateway after 1, 3, and 5 years of storage in the deep space radiation environment.

Soil stabilization with recycled materials improves subgrade performance : research spotlight.

DOT National Transportation Integrated Search

2016-02-29

The use of recycled materials for subgrade stabilization can provide the support needed for construction vehicle loading and more typical long-term traffic loading. This is a particular need in Michigan due to the prevalence of weak subgrade soils. U...

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

Long term contracts, expansion, innovation and stability: North Dakota's lignite mines thrive

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

Buchsbaum, L.

2009-08-15

North Dakota's lignite coal industry is mainly located in three countries in the central part of the state. Its large surface lignite mines are tied through long-term (20-40 years) contracts to power plants. The article talks about operations at three of the most productive mines - the Freedom mine, Falkirk mine and Center Mine. 4 figs.

Development of Interactive Videodisc Instruction for Problem Solving and Armor Skills

DTIC Science & Technology

1986-05-01

skills in both tactical and non-tactical environments. The main body of the lesson is approximately 30 minutes long (linear play time), and is divided...because the test takes a long time and the task is not a problem for most students. The basis on which the above tasks were selected for diagnostic...selection he could given the time available. This is a short-term solution to the task selection problem, but in the long -term a more comprehensive and

Long-Term IQ Stability Using the WISC-IV and WAIS-IV among a Sample of Special Education Students

ERIC Educational Resources Information Center

Spector, Hayley

2013-01-01

The present study investigated the stability of scores on the WISC-IV and WAIS-IV over an approximate six-year period. Previous research using older versions of the WISC and WAIS have suggested that these scales demonstrate strong stability of scores. Since research that has compared the stability of scores between the WISC-IV and the WAIS-IV is…

Life Testing of Yb14MnSb11 for High Performance Thermoelectric Couples

NASA Technical Reports Server (NTRS)

Paik, Jong-Ah; Brandon, Erik; Caillat, Thierry; Ewell, Richard; Fleurial, Jean-Pierre

2011-01-01

The goal of this study is to verify the long term stability of Yb14MnSb11 for high performance thermoelectric (TE) couples. Three main requirements need to be satisfied to ensure the long term stability of thermoelectric couples: 1) stable thermoelectric properties, 2) stable bonding interfaces, and 3) adequate sublimation suppression. The efficiency of the couple is primarily based on the thermoelectric properties of the materials selected for the couple. Therefore, these TE properties should exhibit minimal degradation during the operating period of the thermoelectric couples. The stability of the bonding is quantified by low contact resistances of the couple interfaces. In order to ensure high efficiency, the contact resistances of the bonding interfaces should be negligible. Sublimation suppression is important because the majority of thermoelectric materials used for power generation have peak figures of merit at temperatures where sublimation rates are high. Controlling sublimation is also essential to preserve the efficiency of the couple. During the course of this research, three different life tests were performed with Yb14MnSb11 coupons. TE properties of Yb14MnSb11 exhibited no degradation after 6 months of aging at 1273K, and the electrical contact resistance between a thin metallization layer and the Yb14MnSb11 remained negligible after 1500hr aging at 1273K. A sublimation suppression layer for Yb14MnSb11 was developed and demonstrated for more than 18 months with coupon testing at 1273K. These life test data indicate that thermoelectric elements based on Yb14MnSb11 are a promising technology for use in future high performance thermoelectric power generating couples.

SEALDH-II-An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design-Setup-Accuracy/Stability Stress Test.

PubMed

Buchholz, Bernhard; Kallweit, Sören; Ebert, Volker

2016-12-30

Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal "housekeeping" data to nearly perfectly control SEALDH-II's health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively.

SEALDH-II—An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design–Setup–Accuracy/Stability Stress Test

PubMed Central

Buchholz, Bernhard; Kallweit, Sören; Ebert, Volker

2016-01-01

Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal “housekeeping” data to nearly perfectly control SEALDH-II’s health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively. PMID:28042844

Aggregative stability of fungicidal nanomodifier based on zinc hydrosilicates

NASA Astrophysics Data System (ADS)

Grishina, Anna; Korolev, Evgeniy

2018-03-01

Currently, there is a strong need of high performance multi functional materials in high-rise construction. Obviously, such materials should be characterized by high strength; but for interior rooms biosafety is important as well. The promising direction to obtain both high strength and maintain biosafety in buildings and structures is to manage the structure of mineral binders by means of fungicidal nanomodifier based on zinc hydrosilicates. In the present work the aggregative stability of colloidal solutions of zinc hydrosilicates after one year of storage was studied. It has been established that the concentration of iron (III) hydroxide used to prepare the precursor of zinc hydrosilicates has a significant effect on the long-term aggregative stability: as the concentration of iron (III) hydroxide increases, the resistance of the fungicidal nanomodifier increases. It was found that, despite the minimal concentration of nano-sized zinc hydrosilicates (0.028%), the colloidal solution possesses a low long-term aggregative stability; while in the initial period (not less than 14 days) the colloidal solution of the nanomodifier is aggregatively stable. It is shown that when the ratio in the colloidal solution of the amount of the substance CH3COOH / SiO2 = 0.43 is reached, an increase in the polymerization rate is observed, which is the main cause of low aggregative stability. Colloidal solutions containing zinc hydrosilicates synthesized at a concentration of iron (III) hydroxide used to produce a precursor equal to 0.7% have a long-term aggregative stability and do not significantly change the reduced particle. Such compositions are to be expediently used for the nanomodifying of building composites in order to control their structure formation and to create conditions that impede the development of various mycelial fungi.

Frequency stability of on-orbit GPS Block-I and Block-II Navstar clocks

NASA Astrophysics Data System (ADS)

McCaskill, Thomas B.; Reid, Wilson G.; Buisson, James A.

On-orbit analysis of the Global Positioning System (GPS) Block-I and Block-II Navstar clocks has been performed by the Naval Research Laboratory using a multi-year database. The Navstar clock phase-offset measurements were computed from pseudorange measurements made by the five GPS monitor sites and from the U.S. Naval Observatory precise-time site using single or dual frequency GPS receivers. Orbital data was obtained from the Navstar broadcast ephemeris and from the best-fit, postprocessed orbital ephemerides supplied by the Naval Surface Weapons Center or by the Defense Mapping Agency. Clock performance in the time domain is characterized using frequency-stability profiles with sample times that vary from 1 to 100 days. Composite plots of Navstar frequency stability and time-prediction uncertainty are included as a summary of clock analysis results. The analysis includes plots of the clock phase offset and frequency offset histories with the eclipse seasons superimposed on selected plots to demonstrate the temperature sensitivity of one of the Block-I Navstar rubidium clocks. The potential impact on navigation and on transferring precise time of the degradation in the long-term frequency stability of the rubidium clocks is discussed.

Analysis of quality control data of eight modern radiotherapy linear accelerators: the short- and long-term behaviours of the outputs and the reproducibility of quality control measurements

NASA Astrophysics Data System (ADS)

Kapanen, Mika; Tenhunen, Mikko; Hämäläinen, Tuomo; Sipilä, Petri; Parkkinen, Ritva; Järvinen, Hannu

2006-07-01

Quality control (QC) data of radiotherapy linear accelerators, collected by Helsinki University Central Hospital between the years 2000 and 2004, were analysed. The goal was to provide information for the evaluation and elaboration of QC of accelerator outputs and to propose a method for QC data analysis. Short- and long-term drifts in outputs were quantified by fitting empirical mathematical models to the QC measurements. Normally, long-term drifts were well (<=1%) modelled by either a straight line or a single-exponential function. A drift of 2% occurred in 18 ± 12 months. The shortest drift times of only 2-3 months were observed for some new accelerators just after the commissioning but they stabilized during the first 2-3 years. The short-term reproducibility and the long-term stability of local constancy checks, carried out with a sealed plane parallel ion chamber, were also estimated by fitting empirical models to the QC measurements. The reproducibility was 0.2-0.5% depending on the positioning practice of a device. Long-term instabilities of about 0.3%/month were observed for some checking devices. The reproducibility of local absorbed dose measurements was estimated to be about 0.5%. The proposed empirical model fitting of QC data facilitates the recognition of erroneous QC measurements and abnormal output behaviour, caused by malfunctions, offering a tool to improve dose control.

Multimethod Behavioral Treatment of Long-Term Selective Mutism.

ERIC Educational Resources Information Center

Watson, T. Steuart; Kramer, Jack J.

1992-01-01

Conducted single-subject, experimental research to examine efficacy of treating severe, long-term selective mutism in nine-year-old male using shaping, multiple reinforcers, natural consequences, stimulus fading, and mild aversives. Implemented different treatment regimens in home and school environments. Home intervention resulted in increase in…

Standing genetic variation as a major contributor to adaptation in the Virginia chicken lines selection experiment.

PubMed

Sheng, Zheya; Pettersson, Mats E; Honaker, Christa F; Siegel, Paul B; Carlborg, Örjan

2015-10-01

Artificial selection provides a powerful approach to study the genetics of adaptation. Using selective-sweep mapping, it is possible to identify genomic regions where allele-frequencies have diverged during selection. To avoid false positive signatures of selection, it is necessary to show that a sweep affects a selected trait before it can be considered adaptive. Here, we confirm candidate, genome-wide distributed selective sweeps originating from the standing genetic variation in a long-term selection experiment on high and low body weight of chickens. Using an intercross between the two divergent chicken lines, 16 adaptive selective sweeps were confirmed based on their association with the body weight at 56 days of age. Although individual additive effects were small, the fixation for alternative alleles across the loci contributed at least 40 % of the phenotypic difference for the selected trait between these lines. The sweeps contributed about half of the additive genetic variance present within and between the lines after 40 generations of selection, corresponding to a considerable portion of the additive genetic variance of the base population. Long-term, single-trait, bi-directional selection in the Virginia chicken lines has resulted in a gradual response to selection for extreme phenotypes without a drastic reduction in the genetic variation. We find that fixation of several standing genetic variants across a highly polygenic genetic architecture made a considerable contribution to long-term selection response. This provides new fundamental insights into the dynamics of standing genetic variation during long-term selection and adaptation.

Correlation of high-temperature stability of alpha-chymotrypsin with 'salting-in' properties of solution.

PubMed

Levitsky VYu; Panova, A A; Mozhaev, V V

1994-01-15

A correlation between the stability of alpha-chymotrypsin against irreversible thermal inactivation at high temperatures (long-term stability) and the coefficient of Setchenov equation as a measure of salting-in/out efficiency of solutes in the Hofmeister series has been found. An increase in the concentration of salting-in solutes (KSCN, urea, guanidinium chloride, formamide) leads to a many-fold decrease of the inactivation rate of the enzyme. In contrast, addition of salting-out solutes has a small effect on the long-term stability of alpha-chymotrypsin at high temperatures. The effects of solutes are additive with respect to their salting-in/out capacities; the stabilizing action of the solutes is determined by the calculated Setchenov coefficient of solution. The correlation is explained by a solute-driven shift of the conformational equilibrium between the 'low-temperature' native and the 'high-temperature' denatured forms of the enzyme within the range of the kinetic scheme put forward in the preceding paper in this journal: irreversible inactivation of the high-temperature form proceeds much more slowly compared with the low-temperature form.

Biophysical characterization and conformational stability of Ebola and Marburg virus-like particles.

PubMed

Hu, Lei; Trefethen, Jared M; Zeng, Yuhong; Yee, Luisa; Ohtake, Satoshi; Lechuga-Ballesteros, David; Warfield, Kelly L; Aman, M Javad; Shulenin, Sergey; Unfer, Robert; Enterlein, Sven G; Truong-Le, Vu; Volkin, David B; Joshi, Sangeeta B; Middaugh, C Russell

2011-12-01

The filoviruses, Ebola virus and Marburg virus, cause severe hemorrhagic fever with up to 90% human mortality. Virus-like particles of EBOV (eVLPs) and MARV (mVLPs) are attractive vaccine candidates. For the development of stable vaccines, the conformational stability of these two enveloped VLPs produced in insect cells was characterized by various spectroscopic techniques over a wide pH and temperature range. Temperature-induced aggregation of the VLPs at various pH values was monitored by light scattering. Temperature/pH empirical phase diagrams (EPDs) of the two VLPs were constructed to summarize the large volume of data generated. The EPDs show that both VLPs lose their conformational integrity above about 50°C-60°C, depending on solution pH. The VLPs were maximally thermal stable in solution at pH 7-8, with a significant reduction in stability at pH 5 and 6. They were much less stable in solution at pH 3-4 due to increased susceptibility of the VLPs to aggregation. The characterization data and conformational stability profiles from these studies provide a basis for selection of optimized solution conditions for further vaccine formulation and long-term stability studies of eVLPs and mVLPs. Copyright © 2011 Wiley-Liss, Inc.

Best practices of using shotcrete for wall fascia and slope stabilization (phase 1 study)

DOT National Transportation Integrated Search

2017-06-01

Shotcrete has become attractive and holds potential to replace cast-in-place (CIP) concrete for elements like retaining walls and slope stabilization. However, this practice is still limited due to concerns of drying shrinkage cracking, long-term dur...

Long term benefits of stabilizing soil subgrades

DOT National Transportation Integrated Search

2002-06-01

Chemical admixtures have been used extensively since the mid-eighties in Kentucky to improve bearing strengths of soil subgrades. Most pavements in Kentucky are constructed on clayey soils. Although short-term observations at a small number of sites ...

Microstructural Changes in Inconel ® 740 After Long-Term Aging in the Presence and Absence of Stress

DOE PAGES

Unocic, Kinga A.; Shingledecker, John Paul; Tortorelli, Peter F.

2014-11-18

The Ni-based alloy, Inconel ® 740, is being extensively examined for use in advanced ultrasupercritical steam boilers because its precipitation-strengthened microstructure appears to offer the necessary creep strength under the high temperatures and pressures (up to 760°C and 35 MPa) needed for high efficiency power generation. However, because this application requires extremely long lifetimes under these conditions (up to 30 years), long-term microstructure stability is a major concern. In this study, results from microstructural analyses of Inconel 740 specimens aged at 700 and 750°C in the presence and absence of creep loading for times up to ~31,000 h are presented.more » The primary focus was on the development of the eta η (Ni 3Ti) phase and coarsening of coherent γ'-Ni 3(Al,Ti) precipitates and its depletion near eta/matrix interfaces. Finally, however, despite these processes, Inconel 740 showed adequate long-term microstructural stability to assure adequate creep strength for the intended application.« less

Long-term outcomes of bone augmentation on soft and hard-tissue stability: a systematic review.

PubMed

Lutz, Rainer; Neukam, Friedrich W; Simion, Massimo; Schmitt, Christian M

2015-09-01

Peri-implant hard-tissue augmentation is a widely used clinical procedure. The present review aimed to analyse the current literature regarding medium- and long-term data concerning the stability of peri-implant tissues after hard-tissue augmentation prior or immediately with implant placement. An electronic literature search was performed using Medline (PubMed) databases detecting clinical studies focusing on hard- and soft-tissue stability around dental implants placed either in augmented alveolar ridges or simultaneously with peri-implant bone grafting. The search was limited to articles published between 1995 and December 2014, focusing on clinical studies with a prospective study design assessing peri-implant bone and soft tissue stability over time with a minimum follow-up of 12 months. Recent publications were also searched manually to find any relevant studies that might have been missed using the search criteria noted above. Thirty-seven articles met the inclusion criteria and were included in this systematic review. Since the outcome measures and methods, as well as types of grafts and implants used were so heterogeneous, the performance of meta-analysis was impossible. The highest level of evidence was achieved by randomized clinical trials. Different hard-tissue augmentation procedures seem to show stable peri-implant tissues, although, up to now, long-term stability of the augmented buccal bone is assessed by only few studies. Further research should concentrate on combining three-dimensional radiographic data with non-invasive methods as digital surface measuring techniques or ultrasound evaluation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Phytosiderophore effects on subsurface actinide contaminants: potential for phytostabilization and phytoextraction.

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

Ruggiero, C. E.; Twary, S. N.; Deladurantaye, E.

2003-01-01

In recognition of the need for a safe, effective technology for long term Pu/Th/Actinide stabilization or removal from soils, we have begun an investigation of the potential for phytoremediation (phytostabilization and/or phytoextraction) of Pu and other actinide soil contaminants at DOE sites using phytosiderophore producing plants, and are investigating the contribution of phytosiderophores to actinide mobility in the subsurface environment. Phytoremediation and Phytostabilization have been proven to be a cost-effective, safe, efficient, and publicly acceptable technology for clean up and/or stabilization of contaminant metals . However, no phyto-based technologies have been developed for stabilization or removal of plutonium from soilsmore » and groundwater, and very few have been investigated for other actinides . Current metal-phytostabilization and phytoremediation techniques, predominately based around lead, nickel, and other soft-metal phytoextraction, will almost certainly be inadequate for plutonium due its distinct chemical properties . Phytosiderophore-based phytoremediation may provide technically and financially practical methods for remediation and long-term stewardship of soils that have low to moderate, near surface actinide contamination . We plan to demonstrate potential benefits of phytosiderophore-producing plants for long-term actinide contaminant stabilization by the plant's prevention of soil erosion and actinide migration through hydraulic control and/or through actinide removal through phytoextraction . We may also show possible harm caused by these plants through increased presence of actinide chelators that could increase actinide mobilization and migration in the subsurface environment. This information can then be directly applied by either removal of harmful plants, or be used to develop plant-based soil stabilization/remediation technologies .« less

Factors influencing botulinum toxin dose instability in spasmodic dysphonia patients.

PubMed

Rosow, David E; Pechman, Amanda; Saint-Victor, Sandra; Lo, Kaming; Lundy, Donna S; Casiano, Roy R

2015-05-01

Many patients with spasmodic dysphonia (SD) see consistent effects from botulinum toxin (BTX) injections of the same dose, whereas others require dosage changes over time. We sought to determine whether demographics (age and gender) or environmental factors (smoking) affect the long-term stability of BTX dosing in these patients. Retrospective review. Charts of all patients undergoing BTX injection for adductor SD were reviewed. Dosage change, defined as whether there was any difference in total dosage used between two beneficial injections, was used as a measure of dosing stability. Beneficial injections were indicated by a voice rating score of at least three of four and any non-zero duration of improved voice. Logistic regression analysis was performed to determine whether age, gender, smoking status, or duration of treatment correlated with odds of having a dosage change. A total of 211 patients were ultimately included. Age, gender, and smoking status were all found to have no correlative effect on dosing stability. The only factor that was predictive of dose stability was the number of previous beneficial injections, as every additional injection led to decreased odds of a change in dosage for the next injection (odds ratio=0.964; 95% confidence interval=0.947-0.981). Dosage of BTX injections for long-term treatment of SD has a significant propensity to remain stable over time. Factors such as age, gender, and smoking status do not appear to influence the dosage stability. These findings should allow for better patient counseling regarding expectations for their long-term treatment. Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Short-term Action Intentions Overrule Long-Term Semantic Knowledge

ERIC Educational Resources Information Center

van Elk, M.; van Schie, H.T.; Bekkering, H.

2009-01-01

In the present study, we investigated whether the preparation of an unusual action with an object (e.g. bringing a cup towards the eye) could selectively overrule long-term semantic representations. In the first experiment it was found that unusual action intentions activated short-term semantic goal representations, rather than long-term…

Interplay between black carbon and minerals contributes to long term carbon stabilization and mineral transformation

NASA Astrophysics Data System (ADS)

Liang, B.; Weng, Y. T.; Wang, C. C.; Chiang, C. C.; Liu, C. C.; Lehmann, J.

2017-12-01

Black carbon receives increasing global wide research attention due to its role in carbon sequestration, soil fertility enhancement and remediation application. Generally considered chemically stable in bulk, the reactive surface of BC can interplays with minerals and form strong chemical bondage, which renders physical protection of BC and contributes to its long term stabilization. Using historical BC-rich Amazonian Dark Earth (ADE), we probe the in-situ organo-mineral association and transformation of BC and minerals over a millennium scale using various synchrotron-based spectroscopic (XANES, FTIR) and microscopic (TXM) methods. Higher content of SRO minerals was found in BC-rich ADE compare to adjacent tropical soils. The iron signature found in BC-rich ADE was mainly ferrihydrite/lepidocrocite, a more reactive form of Fe compared to goethite, which was dominant in adjacent soil. Abundant nano minerals particles were observed in-situ associated with BC surface, in clusters and layers. The organo-mineral interaction lowers BC bioavailability and enhances its long-term stabilization in environment, while at the same time, transforms associated minerals into more reactive forms under rapid redox/weathering environment. The results suggest that mineral physical protection for BC sequestration may be more important than previous understanding. The scale up application of BC/biochar into agricultural systems and natural environments have long lasting impact on the in-situ transformation of associated minerals.

Stable and efficient nitrogen-containing-carbon based electrocatalysts for reactions in energy conversion systems.

PubMed

Wang, Sicong; Teng, Zhenyuan; Wang, Chengyin; Wang, Guoxiu

2018-05-17

High activity and stability are crucial for practical electrocatalysts used for reactions in fuel cells, metal-air batteries and water electrolysis including ORR, HER, OER and oxidation reactions of formic acid and alcohols. N-C based electrocatalysts have shown promising prospects for catalyzing these reactions, however, there is no systematic review for strategies toward engineering active and stable N-C based electrocatalysts reported by far. Herein, a comprehensive comparison of recently reported N-C based electrocatalysts regarding both electrocatalytic activity and long-term stability is presented. In the first part of this review, relationships between electrocatalytic reactions and element selections for modifying N-C based materials are discussed. Afterwards, synthesis methods for N-C based electrocatalysts are summarized, and synthetic strategies for highly stable N-C based electrocatalysts are presented. Multiple tables containing data on crucial parameters for both electrocatalytic activity and stability are displayed in this review. Finally, constructing M-Nx moieties is proposed as the most promising engineering strategy for stable N-C based electrocatalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stability and self-passivation of copper vanadate photoanodes under chemical, electrochemical, and photoelectrochemical operation

DOE PAGES

Zhou, Lan; Yan, Qimin; Yu, Jie; ...

2016-03-14

We discuss how deployment of solar fuels technology requires photoanodes and that long term stability, can be accomplished using light absorbers that self-passivate under operational conditions. We recently reported that several copper vanadates are promising photoanode materials, and their stability and self-passivation is demonstrated through a combination of Pourbaix calculations and combinatorial experimentation.

Development of a Predictive Model for the Long-Term Stability Assessment of Drug-In-Adhesive Transdermal Films Using Polar Pressure-Sensitive Adhesives as Carrier/Matrix.

PubMed

Chenevas-Paule, Clémence; Wolff, Hans-Michael; Ashton, Mark; Schubert, Martin; Dodou, Kalliopi

2017-05-01

Drug crystallization in transdermal drug delivery systems is a critical quality defect. The impact of drug load and hydration on the physical stability of polar (acrylic) drug-in-adhesive (DIA) films was investigated with the objective to identify predictive formulation parameters with respect to drug solubility and long-term stability. Medicated acrylic films were prepared over a range of drug concentrations below and above saturation solubility and were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, polarized microscopy, and dynamic vapor sorption (DVS) analysis. Physical stability of medicated films was monitored over 4 months under different storage conditions and was dependent on solubility parameters, Gibbs free energy for drug phase transition from the amorphous to the crystalline state, and relative humidity. DVS data, for assessing H-bonding capacity experimentally, were essential to predict physical stability at different humidities and were used together with Gibbs free energy change and the Hoffman equation to develop a new predictive thermodynamic model to estimate drug solubility and stability in DIA films taking into account relative humidity. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Examining the long-term stability of overgeneral autobiographical memory.

PubMed

Sumner, Jennifer A; Mineka, Susan; Zinbarg, Richard E; Craske, Michelle G; Vrshek-Schallhorn, Suzanne; Epstein, Alyssa

2014-01-01

Overgeneral autobiographical memory (OGM) is a proposed trait-marker for vulnerability to depression, but relatively little work has examined its long-term stability. This study investigated the stability of OGM over several years in 271 late adolescents and young adults participating in a larger longitudinal study of risk for emotional disorders. The Autobiographical Memory Test (AMT) was administered twice, with test-retest intervals ranging from approximately 3 to 6 years. There was evidence of significant but modest stability in OGM over several years. Specifically, Spearman rank correlations (ρs) between the proportions of specific and categoric memories generated on the two AMTs were .31 and .32, respectively. We did not find evidence that the stability of OGM was moderated by the length of the test-retest interval. Furthermore, the stability coefficients for OGM for individuals with and without a lifetime history of major depressive disorder (MDD) were relatively similar in magnitude and not significantly different from one another (ρs=.34 and .42 for the proportions of specific and categoric memories for those with a history of MDD; ρs=.31 for both the proportions of specific and categoric memories for those without a history of MDD). Implications for the conceptualisation of OGM are discussed.

Fabrication of bimetallic Cu/Au nanotubes and their sensitive, selective, reproducible and reusable electrochemical sensing of glucose

NASA Astrophysics Data System (ADS)

Tee, Si Yin; Ye, Enyi; Pan, Pei Hua; Lee, Coryl Jing Jun; Hui, Hui Kim; Zhang, Shuang-Yuan; Koh, Leng Duei; Dong, Zhili; Han, Ming-Yong

2015-06-01

Herein, we report a facile two-step approach to produce gold-incorporated copper (Cu/Au) nanostructures through controlled disproportionation of the Cu+-oleylamine complex at 220 °C to form copper nanowires and the subsequent reaction with Au3+ at different temperatures of 140, 220 and 300 °C. In comparison with copper nanowires, these bimetallic Cu/Au nanostructures exhibit their synergistic effect to greatly enhance glucose oxidation. Among them, the shape-controlled Cu/Au nanotubes prepared at 140 °C show the highest electrocatalytic activity for non-enzymatic glucose sensing in alkaline solution. In addition to high sensitivity and fast response, the Cu/Au nanotubes possess high selectivity against interferences from other potential interfering species and excellent reproducibility with long-term stability. By introducing gold into copper nanostructures at a low level of 3, 1 and 0.1 mol% relative to the initial copper precursor, a significant electrocatalytic enhancement of the resulting bimetallic Cu/Au nanostructures starts to occur at 1 mol%. Overall, the present fabrication of stable Cu/Au nanostructures offers a promising low-cost platform for sensitive, selective, reproducible and reusable electrochemical sensing of glucose.Herein, we report a facile two-step approach to produce gold-incorporated copper (Cu/Au) nanostructures through controlled disproportionation of the Cu+-oleylamine complex at 220 °C to form copper nanowires and the subsequent reaction with Au3+ at different temperatures of 140, 220 and 300 °C. In comparison with copper nanowires, these bimetallic Cu/Au nanostructures exhibit their synergistic effect to greatly enhance glucose oxidation. Among them, the shape-controlled Cu/Au nanotubes prepared at 140 °C show the highest electrocatalytic activity for non-enzymatic glucose sensing in alkaline solution. In addition to high sensitivity and fast response, the Cu/Au nanotubes possess high selectivity against interferences from other potential interfering species and excellent reproducibility with long-term stability. By introducing gold into copper nanostructures at a low level of 3, 1 and 0.1 mol% relative to the initial copper precursor, a significant electrocatalytic enhancement of the resulting bimetallic Cu/Au nanostructures starts to occur at 1 mol%. Overall, the present fabrication of stable Cu/Au nanostructures offers a promising low-cost platform for sensitive, selective, reproducible and reusable electrochemical sensing of glucose. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02399h

A kinase-dependent feedforward loop affects CREBB stability and long term memory formation.

PubMed

Lee, Pei-Tseng; Lin, Guang; Lin, Wen-Wen; Diao, Fengqiu; White, Benjamin H; Bellen, Hugo J

2018-02-23

In Drosophila , long-term memory (LTM) requires the cAMP-dependent transcription factor CREBB, expressed in the mushroom bodies (MB) and phosphorylated by PKA. To identify other kinases required for memory formation, we integrated Trojan exons encoding T2A-GAL4 into genes encoding putative kinases and selected for genes expressed in MB. These lines were screened for learning/memory deficits using UAS-RNAi knockdown based on an olfactory aversive conditioning assay. We identified a novel, conserved kinase, Meng-Po ( MP , CG11221 , SBK1 in human), the loss of which severely affects 3 hr memory and 24 hr LTM, but not learning. Remarkably, memory is lost upon removal of the MP protein in adult MB but restored upon its reintroduction. Overexpression of MP in MB significantly increases LTM in wild-type flies showing that MP is a limiting factor for LTM. We show that PKA phosphorylates MP and that both proteins synergize in a feedforward loop to control CREBB levels and LTM. key words: Drosophila, Mushroom bodies, SBK1, deGradFP, T2A-GAL4, MiMIC.

Science Data Report for the Optical Properties Monitor (OPM) Experiment

NASA Technical Reports Server (NTRS)

Wilkes, Donald R.; Zwiener, James M.

1999-01-01

Long term stability of spacecraft materials when exposed to the space environment continues to be a major area of investigation. The natural and induced environment surrounding a spacecraft can decrease material performance and limit useful lifetimes. The Optical Properties Monitor (OPM) experiment provided the capability to perform the important flight testing of materials and was flown on the Russian Mir Station to study the long term effects of the natural and induced space environment on materials. The core of the OPM in-flight analysis was three independent optical instruments. These instruments included an integrating sphere spectral reflectometer, a vacuum ultraviolet spectrometer, and a Total Integrated Scatter instrument. The OPM also monitored selected components of the environment including molecular contamination. The OPM was exposed on the exterior of the Mir Docking Module for approximately 8-1/2 months. This report describes the OPM experiment, a brief background of its development, program organization, experiment description, mission overview including space environment definition, performance overview, materials data including flight and ground data, in-depth post flight analysis including ground analysis measurements and a summary discussion of the findings and results.

Dynamical Stability and Long-term Evolution of Rotating Stellar Systems

NASA Astrophysics Data System (ADS)

Varri, Anna L.; Vesperini, E.; McMillan, S. L. W.; Bertin, G.

2011-05-01

We present the first results of an extensive survey of N-body simulations designed to investigate the dynamical stability and the long-term evolution of two new families of self-consistent stellar dynamical models, characterized by the presence of internal rotation. The first family extends the well-known King models to the case of axisymmetric systems flattened by solid-body rotation while the second family is characterized by differential rotation. The equilibrium configurations thus obtained can be described in terms of two dimensionless parameters, which measure the concentration and the amount of rotation, respectively. Slowly rotating configurations are found to be dynamically stable and we followed their long-term evolution, in order to evaluate the interplay between collisional relaxation and angular momentum transport. We also studied the stability of rapidly rotating models, which are characterized by the presence of a toroidal core embedded in an otherwise quasi-spherical configuration. In both cases, a description in terms of the radial and global properties, such as the ratio between the ordered kinetic energy and the gravitational energy of the system, is provided. Because the role of angular momentum in the process of cluster formation is only partly understood, we also undertook a preliminary investigation of the violent relaxation of simple systems initially characterized by approximate solid-body rotation. The properties of the final equilibrium configurations thus obtained are compared with those of the above-described family of differentially rotating models.

A Controlled Single-Case Treatment of Severe Long-Term Selective Mutism in a Child with Mental Retardation

ERIC Educational Resources Information Center

Facon, Bruno; Sahiri, Safia; Riviere, Vinca

2008-01-01

The aim of the present study was to demonstrate the efficacy of combining two operant learning procedures--shaping and fading--for treating selective mutism. The participant was a 12-year-old boy with mental retardation presenting a severe long-term selective mutism. The treatment was aimed at increasing the loudness of his vocalizations in an…

Memory-guided selective attention: Single experiences with conflict have long-lasting effects on cognitive control.

PubMed

Brosowsky, Nicholaus P; Crump, Matthew J C

2018-05-17

Adjustments in cognitive control, as measured by congruency sequence effects, are thought to be influenced by both external stimuli and internal goals. However, this dichotomy has often overshadowed the potential contribution of past experience stored in memory. Here, we examine the role of long-term episodic memory in guiding selective attention. Our aim was to demonstrate new evidence that selective attention can be modulated by long-term retrieval of stimulus-specific attentional control settings. All the experiments used a modified flanker task involving multiple unique stimuli. Critically, each stimulus was only presented twice during the experiment: first as a prime, and second as a probe. Experiments 1 and 2 varied the number of intervening trials between prime and probe and manipulated the amount of conflict using a secondary task. Experiment 3 ensured that specific colors assigned to prime stimuli were not repeated when presented as probes. Across both Experiments 1 and 2, we consistently found smaller congruency effects on probe trials when its associated prime trial was incongruent compared with congruent, demonstrating long-term congruency sequence effects. However, Experiment 3 showed no evidence for long-term effects. These findings suggest long-term preservation of selective attention processing at the episodic level, and implicate a role for memory in updating cognitive control. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Issues in the Development of Long Term Care Gerontology Centers: The Centers Concept. Selected Topics in Long Term Care. Volume 6.

ERIC Educational Resources Information Center

Mortenson, Lee E.; Berdes, Celia M.

This document, one in a series developed to provide technical assistance to 22 Long-Term Care Gerontology Centers, describes the current administrative and structural phenomenon of these centers. Precedents useful in assessing both the current climate and actual prospects for development of long term care centers are cited. The first section…

Biodiversity-ecosystem functioning relationships in a long-term non-weeded field experiment.

PubMed

Veen, Ciska G F; van der Putten, Wim H; Bezemer, T Martijn

2018-05-30

Many grassland biodiversity experiments show a positive relationship between biodiversity and ecosystem functioning, however, in most these experiments plant communities are established by sowing and natural colonization is prevented by selective weeding of non-sown species. During ecosystem restoration, for example on abandoned fields, plant communities start on bare soil, and diversity is often manipulated in a single sowing event. How such initial plant diversity manipulations influence plant biodiversity development and ecosystem functioning is not well understood. We examined how relationships between taxonomic and functional diversity, biomass production and stability develop over 16 years in non-weeded plots sown with 15 species, 4 species, or that were not sown. We found that sown plant communities become functionally similar to unsown, naturally colonized plant communities. However, initial sowing treatments had long-lasting effects on species composition and taxonomic diversity. We found only few relationships between biomass production, or stability in biomass production, and functional or taxonomic diversity, and the ones we observed were negative. In addition, the cover of dominant plant species was positively related to biomass production and stability. We conclude that effects of introducing plant species at the start of secondary succession can persist for a long time, and that in secondary succession communities with natural plant species dynamics diversity-functioning relationships can be weak or negative. Moreover, our findings indicate that in systems where natural colonization of species is allowed effects of plant dominance may underlie diversity-functioning relationships. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Effects of trawl selectivity and genetic parameters on fish body length under long-term trawling

NASA Astrophysics Data System (ADS)

Yu, Yang; Sun, Peng; Cui, He; Sheng, Huaxiang; Zhao, Fenfang; Tang, Yanli; Chen, Zelin

2015-10-01

Long-term fishing pressure affects the biological characteristics of exploited fish stocks. The biological characteristics of hairtail ( Trichiurus lepturus) in the East China Sea are unable to recover because of long-term trawling. Fishing induces evolutionary effects on the fish's biological characteristics. Evidence of these changes includes small size at age, a shift to earlier age structure, and early maturation. Natural and artificial selection usually affect the fish's life history. Selection can induce different chances of reproduction, and individual fish can give a different genetic contribution to the next generation. In this study, analysis of time-dependent probability of significance and test of sensitivity were used to explore the effects of fish exploitation rate, mesh size, and heritability with long-term trawling. Results showed that fishing parameters were important drivers to exploited fish population. However, genetic traits altered by fishing were slow, and the changes in biological characteristics were weaker than those caused by fishing selection. Exploitation rate and mesh size exhibited similar evolutionary trend tendency under long-term fishing. The time-dependent probability of significance trend showed a gradual growth and tended to be stable. Therefore, the direction of fishing-induced evolution and successful management of fish species require considerable attention to contribute to sustainable fisheries in China.

The Adults in the Making Program: Long-Term Protective Stabilizing Effects on Alcohol Use and Substance Use Problems for Rural African American Emerging Adults

ERIC Educational Resources Information Center

Brody, Gene H.; Yu, Tianyi; Chen, Yi-fu; Kogan, Steven M.; Smith, Karen

2012-01-01

Objective: This report addresses the long-term efficacy of the Adults in the Making (AIM) prevention program on deterring the escalation of alcohol use and development of substance use problems, particularly among rural African American emerging adults confronting high levels of contextual risk. Method: African American youths (M age, pretest =…

Long-term stability in biomass and production of terpene indole alkaloids by hairy root culture of Rauvolfia serpentina and cost approximation to endorse commercial realism.

PubMed

Pandey, Pallavi; Kaur, Ranjeet; Singh, Sailendra; Chattopadhyay, Sunil Kumar; Srivastava, Santosh Kumar; Banerjee, Suchitra

2014-07-01

The effect of 6 years of cultivation and use of table-sugar (TS) on the biomass/terpene alkaloid productivities and rol gene expression were studied in a hairy root (HR) clone of Rauvolfia serpentina. The media cost could be reduced >94 % by replacing sucrose (SUC) with TS—an unexplored avenue for HR cultivation. The overall productivities increased over long-term cultivation with sugar proving superior to SUC for biomass (24.4 ± 2.11 g/l DW after 40 days to 17.31 % higher) and reserpine (0.094 ± 0.008 % DW after 60 days to 193.8 % more) production. The latter however revealed comparatively better yields concerning ajmaline (0.507 ± 0.048 % DW after 60 days to 61.98 % higher) and yohimbine (0.628 ± 0.062 % DW after 60 days to 38.32 % higher), respectively. PCR amplification of rol genes confirmed long-term expression stability.

Proceedings of the 6. international conference on stability and handling of liquid fuels. Volume 1

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

Giles, H.N.

1998-12-01

Volume 1 of these proceedings contain 29 papers related to aviation fuels and long term and strategic storage. Studies investigated fuel contamination, separation processes, measurement techniques, thermal stability, compatibility with fuel system materials, oxidation reactions, and degradation during storage.

Herbivory and drought generate short-term stochasticity and long-term stability in a savanna understory community.

PubMed

Riginos, Corinna; Porensky, Lauren M; Veblen, Kari E; Young, Truman P

2018-03-01

Rainfall and herbivory are fundamental drivers of grassland plant dynamics, yet few studies have examined long-term interactions between these factors in an experimental setting. Understanding such interactions is important, as rainfall is becoming increasingly erratic and native wild herbivores are being replaced by livestock. Livestock grazing and episodic low rainfall are thought to interact, leading to greater community change than either factor alone. We examined patterns of change and stability in herbaceous community composition through four dry periods, or droughts, over 15 years of the Kenya Long-term Exclosure Experiment (KLEE), which consists of six different combinations of cattle, native wild herbivores (e.g., zebras, gazelles), and mega-herbivores (giraffes, elephants). We used principal response curves to analyze the trajectory of change in each herbivore treatment relative to a common initial community and asked how droughts contributed to community change in these treatments. We examined three measures of stability (resistance, variability, and turnover) that correspond to different temporal scales and found that each had a different response to grazing. Treatments that included both cattle and wild herbivores had higher resistance (less net change over 15 years) but were more variable on shorter time scales; in contrast, the more lightly grazed treatments (no herbivores or wild herbivores only) showed lower resistance due to the accumulation of consistent, linear, short-term change. Community change was greatest during and immediately after droughts in all herbivore treatments. But, while drought contributed to directional change in the less grazed treatments, it contributed to both higher variability and resistance in the more heavily grazed treatments. Much of the community change in lightly grazed treatments (especially after droughts) was due to substantial increases in cover of the palatable grass Brachiaria lachnantha. These results illustrate how herbivory and drought can act together to cause change in grassland communities at the moderate to low end of a grazing intensity continuum. Livestock grazing at a moderate intensity in a system with a long evolutionary history of grazing contributed to long-term stability. This runs counter to often-held assumptions that livestock grazing leads to directional, destabilizing shifts in grassland systems. © 2017 by the Ecological Society of America.

Stabilization of Live Attenuated Influenza Vaccines by Freeze Drying, Spray Drying, and Foam Drying.

PubMed

Lovalenti, Phillip M; Anderl, Jeff; Yee, Luisa; Nguyen, Van; Ghavami, Behnaz; Ohtake, Satoshi; Saxena, Atul; Voss, Thomas; Truong-Le, Vu

2016-05-01

The goal of this research is to develop stable formulations for live attenuated influenza vaccines (LAIV) by employing the drying methods freeze drying, spray drying, and foam drying. Formulated live attenuated Type-A H1N1 and B-strain influenza vaccines with a variety of excipient combinations were dried using one of the three drying methods. Process and storage stability at 4, 25 and 37°C of the LAIV in these formulations was monitored using a TCID50 potency assay. Their immunogenicity was also evaluated in a ferret model. The thermal stability of H1N1 vaccine was significantly enhanced through application of unique formulation combinations and drying processes. Foam dried formulations were as much as an order of magnitude more stable than either spray dried or freeze dried formulations, while exhibiting low process loss and full retention of immunogenicity. Based on long-term stability data, foam dried formulations exhibited a shelf life at 4, 25 and 37°C of >2, 1.5 years and 4.5 months, respectively. Foam dried LAIV Type-B manufactured using the same formulation and process parameters as H1N1 were imparted with a similar level of stability. Foam drying processing methods with appropriate selection of formulation components can produce an order of magnitude improvement in LAIV stability over other drying methods.

Utility of High Throughput Screening Techniques to Predict Stability of Monoclonal Antibody Formulations During Early Stage Development.

PubMed

Goldberg, Deborah S; Lewus, Rachael A; Esfandiary, Reza; Farkas, David C; Mody, Neil; Day, Katrina J; Mallik, Priyanka; Tracka, Malgorzata B; Sealey, Smita K; Samra, Hardeep S

2017-08-01

Selecting optimal formulation conditions for monoclonal antibodies for first time in human clinical trials is challenging due to short timelines and reliance on predictive assays to ensure product quality and adequate long-term stability. Accelerated stability studies are considered to be the gold standard for excipient screening, but they are relatively low throughput and time consuming. High throughput screening (HTS) techniques allow for large amounts of data to be collected quickly and easily, and can be used to screen solution conditions for early formulation development. The utility of using accelerated stability compared to HTS techniques (differential scanning light scattering and differential scanning fluorescence) for early formulation screening was evaluated along with the impact of excipients of various types on aggregation of monoclonal antibodies from multiple IgG subtypes. The excipient rank order using quantitative HTS measures was found to correlate with accelerated stability aggregation rate ranking for only 33% (by differential scanning fluorescence) to 42% (by differential scanning light scattering) of the antibodies tested, due to the high intrinsic stability and minimal impact of excipients on aggregation rates and HTS data. Also explored was a case study of employing a platform formulation instead of broader formulation screening for early formulation development. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

The effect of gene interactions on the long-term response to selection.

PubMed

Paixão, Tiago; Barton, Nicholas H

2016-04-19

The role of gene interactions in the evolutionary process has long been controversial. Although some argue that they are not of importance, because most variation is additive, others claim that their effect in the long term can be substantial. Here, we focus on the long-term effects of genetic interactions under directional selection assuming no mutation or dominance, and that epistasis is symmetrical overall. We ask by how much the mean of a complex trait can be increased by selection and analyze two extreme regimes, in which either drift or selection dominate the dynamics of allele frequencies. In both scenarios, epistatic interactions affect the long-term response to selection by modulating the additive genetic variance. When drift dominates, we extend Robertson's [Robertson A (1960)Proc R Soc Lond B Biol Sci153(951):234-249] argument to show that, for any form of epistasis, the total response of a haploid population is proportional to the initial total genotypic variance. In contrast, the total response of a diploid population is increased by epistasis, for a given initial genotypic variance. When selection dominates, we show that the total selection response can only be increased by epistasis when some initially deleterious alleles become favored as the genetic background changes. We find a simple approximation for this effect and show that, in this regime, it is the structure of the genotype-phenotype map that matters and not the variance components of the population.

Structure, stability and behaviour of nucleic acids in ionic liquids

PubMed Central

Tateishi-Karimata, Hisae; Sugimoto, Naoki

2014-01-01

Nucleic acids have become a powerful tool in nanotechnology because of their conformational polymorphism. However, lack of a medium in which nucleic acid structures exhibit long-term stability has been a bottleneck. Ionic liquids (ILs) are potential solvents in the nanotechnology field. Hydrated ILs, such as choline dihydrogen phosphate (choline dhp) and deep eutectic solvent (DES) prepared from choline chloride and urea, are ‘green’ solvents that ensure long-term stability of biomolecules. An understanding of the behaviour of nucleic acids in hydrated ILs is necessary for developing DNA materials. We here review current knowledge about the structures and stabilities of nucleic acids in choline dhp and DES. Interestingly, in choline dhp, A–T base pairs are more stable than G–C base pairs, the reverse of the situation in buffered NaCl solution. Moreover, DNA triplex formation is markedly stabilized in hydrated ILs compared with aqueous solution. In choline dhp, the stability of Hoogsteen base pairs is comparable to that of Watson–Crick base pairs. Moreover, the parallel form of the G-quadruplex is stabilized in DES compared with aqueous solution. The behaviours of various DNA molecules in ILs detailed here should be useful for designing oligonucleotides for the development of nanomaterials and nanodevices. PMID:25013178

Organomineral Complexation at the Nanoscale: Iron Speciation and Soil Carbon Stabilization

NASA Astrophysics Data System (ADS)

Coward, E.; Thompson, A.; Plante, A. F.

2016-12-01

Much of the uncertainty in the biogeochemical behavior of soil carbon (C) in tropical ecosystems derives from an incomplete understanding of soil C stabilization processes. The 2:1 phyllosilicate clays often associated with temperate organomineral complexation are largely absent in tropical soils due to extensive weathering. In contrast, these soils contain an abundance of Fe- and Al-containing short-range-order (SRO) mineral phases capable of C stabilization through sorption or co-precipitation, largely enabled by high specific surface area (SSA). SRO-mediated organomineral associations may thus prove a critical, yet matrix-selective, driver of the long-term C stabilization capacity observed in tropical soils. Characterizing the interactions between inherently heterogeneous organic matter and amorphous mineralogy presses the limits of current analytical techniques. This work pairs inorganic selective dissolution with high-resolution assessment of Fe speciation to determine the contribution of extracted mineral phases to the mineral matrix, and to C stabilization capacity. Surface (0-20 cm) samples were taken from 20 quantitative soil pits within the Luquillo Critical Zone Observatory in northeast Puerto Rico stratified across granodioritic and volcaniclastic parent materials. 57Fe-Mössbauer spectroscopy (MBS) and x-ray diffraction (XRD) before and after Fe-SOM extraction were used to assess changes in the mineralogical matrix associated with SOM dissolution, while N2-BET sorption was used to determine the contributions of the extractable phases to SSA. Results indicate (1) selective extraction of soil C produces significant shifts in Fe phase distribution, (2) SRO minerals contribute substantially to SSA, and (3) SRO minerals appear protected by more crystalline phases via physical mechanisms, rather than dissolution-dependent chemical bonds. This nanoscale characterization of Fe-C complexes thus provides evidence for both anticipated mineral-organic and unexpected mineral-mineral associations, which may dynamically impact the temporal fate of tropical soil C.

Metrological properties of {CO 2}/{OsO 4} optical frequency standard

NASA Astrophysics Data System (ADS)

Acef, O.

1997-02-01

Recent progress on the metrological performance of the BNM-LPTF {CO 2}/{OsO 4} frequency standards in the {28}/{29}THz range, using OsO 4 molecular transitions as a frequency reference is reported. Significant improvements in terms of both short-term stability ( {6.6×10 -14}/{τup to τ=300s }) and long-term stability (4 × 10 -15 up to τ = 1 000 s, Δν ˜ 0.1 Hz) are obtained. Long term reproducibility (over more than 18 months) of about 3 × 10 -13 has been achieved. This high level enables the transfer, in terms of absolute frequency at the 3 × 10 -13 level of uncertainty, from primary frequency standards in the microwave domain to near infrared and visible domains, using frequency chains with {CO 2}/{OsO 4} as a transfer frequency standard. Preliminary estimates of the main effects which may shift the OsO 4 center line are reported.

Long-Term Morphological and Microarchitectural Stability of Tissue-Engineered, Patient-Specific Auricles In Vivo

PubMed Central

Cohen, Benjamin Peter; Hooper, Rachel C.; Puetzer, Jennifer L.; Nordberg, Rachel; Asanbe, Ope; Hernandez, Karina A.; Spector, Jason A.

2016-01-01

Current techniques for autologous auricular reconstruction produce substandard ear morphologies with high levels of donor-site morbidity, whereas alloplastic implants demonstrate poor biocompatibility. Tissue engineering, in combination with noninvasive digital photogrammetry and computer-assisted design/computer-aided manufacturing technology, offers an alternative method of auricular reconstruction. Using this method, patient-specific ears composed of collagen scaffolds and auricular chondrocytes have generated auricular cartilage with great fidelity following 3 months of subcutaneous implantation, however, this short time frame may not portend long-term tissue stability. We hypothesized that constructs developed using this technique would undergo continued auricular cartilage maturation without degradation during long-term (6 month) implantation. Full-sized, juvenile human ear constructs were injection molded from high-density collagen hydrogels encapsulating juvenile bovine auricular chondrocytes and implanted subcutaneously on the backs of nude rats for 6 months. Upon explantation, constructs retained overall patient morphology and displayed no evidence of tissue necrosis. Limited contraction occurred in vivo, however, no significant change in size was observed beyond 1 month. Constructs at 6 months showed distinct auricular cartilage microstructure, featuring a self-assembled perichondrial layer, a proteoglycan-rich bulk, and rounded cellular lacunae. Verhoeff's staining also revealed a developing elastin network comparable to native tissue. Biochemical measurements for DNA, glycosaminoglycan, and hydroxyproline content and mechanical properties of aggregate modulus and hydraulic permeability showed engineered tissue to be similar to native cartilage at 6 months. Patient-specific auricular constructs demonstrated long-term stability and increased cartilage tissue development during extended implantation, and offer a potential tissue-engineered solution for the future of auricular reconstructions. PMID:26847742

[Study on mechanism of SOM stabilization of paddy soils under long-term fertilizations].

PubMed

Luo, Lu; Zhou, Ping; Tong, Cheng-Li; Shi, Hui; Wu, Jin-Shui; Huang, Tie-Ping

2013-02-01

Fourier transform infrared spectroscopy (FTIR) was applied to study the structure of soil organic matter (SOM) of paddy soils under long-term different fertilization treatments. The aim was to clarify the different distribution of SOM between different fertilization methods and between topsoil and subsoil, and to explore the stability mechanism of SOM under different fertilization treatments. The results showed that the content of topsoil organic carbon (SOC) was the highest under organic-inorganic fertilizations, with the increment of SOC by 18.5%, 12.9% and 18.4% under high organic manure (HOM), low organic manure (LOM) and straw returning (STW) respectively compared with no fertilization treatment (CK). The long-term fertilizations also changed the chemical structure of SOM. As compared with CK, different fertilization treatments increased the functional group absorbing intensity of chemical resistance compounds (aliphatic, aromaticity), carbohydrate and organo-silicon compounds, which was the most distinctive under treatments of HOM, LOM and STW. For example, the absorbing intensity of alkyl was 0.30, 0.25 and 0.29 under HOM, LOM and STW, respectively. These values were increased by 87% , 56% and 81% as compared with that under CK treatment. The functional group absorbing intensity of SOM in the topsoil was stronger than that in the subsoil, with the most distinctive difference under HOM, LOM and STW treatments. The present research indicated that the enhanced chemical resistance of functional group of SOM may contribute to the high contents of SOC in the paddy soils under long-term organic-inorganic fertilizations, which also suggested a chemical stabilization mechanism of SOM in the paddy soils.

Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Remedial action selection report. Revised final report

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

Not Available

1991-12-01

The uranium mill tailings site near Durango, Colorado, was one of 24 inactive uranium mill sites designated to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE`s Remedial Action Plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which has been developed to serve a two-fold purpose.more » First, it describes the activities that have been conducted by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium mill processing site near Durango, Colorado. Secondly, this document and the rest of the RAP, upon concurrence and execution by the DOE, the State of Colorado, and the NRC, become Appendix B of the Cooperative Agreement between the DOE and the State of Colorado.« less

Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Remedial action selection report

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

Not Available

1991-12-01

The uranium mill tailings site near Durango, Colorado, was one of 24 inactive uranium mill sites designated to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's Remedial Action Plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which has been developed to serve a two-fold purpose.more » First, it describes the activities that have been conducted by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium mill processing site near Durango, Colorado. Secondly, this document and the rest of the RAP, upon concurrence and execution by the DOE, the State of Colorado, and the NRC, become Appendix B of the Cooperative Agreement between the DOE and the State of Colorado.« less

Chemical stabilization of metals and arsenic in contaminated soils using oxides--a review.

PubMed

Komárek, Michael; Vaněk, Aleš; Ettler, Vojtěch

2013-01-01

Oxides and their precursors have been extensively studied, either singly or in combination with other amendments promoting sorption, for in situ stabilization of metals and As in contaminated soils. This remediation option aims at reducing the available fraction of metal(loid)s, notably in the root zone, and thus lowering the risks associated with their leaching, ecotoxicity, plant uptake and human exposure. This review summarizes literature data on mechanisms involved in the immobilization process and presents results from laboratory and field experiments, including the subsequent influence on higher plants and aided phytostabilization. Despite the partial successes in the field, recent knowledge highlights the importance of long-term and large-scale field studies evaluating the stability of the oxide-based amendments in the treated soils and their efficiency in the long-term. Copyright © 2012 Elsevier Ltd. All rights reserved.

A VLSI recurrent network of integrate-and-fire neurons connected by plastic synapses with long-term memory.

PubMed

Chicca, E; Badoni, D; Dante, V; D'Andreagiovanni, M; Salina, G; Carota, L; Fusi, S; Del Giudice, P

2003-01-01

Electronic neuromorphic devices with on-chip, on-line learning should be able to modify quickly the synaptic couplings to acquire information about new patterns to be stored (synaptic plasticity) and, at the same time, preserve this information on very long time scales (synaptic stability). Here, we illustrate the electronic implementation of a simple solution to this stability-plasticity problem, recently proposed and studied in various contexts. It is based on the observation that reducing the analog depth of the synapses to the extreme (bistable synapses) does not necessarily disrupt the performance of the device as an associative memory, provided that 1) the number of neurons is large enough; 2) the transitions between stable synaptic states are stochastic; and 3) learning is slow. The drastic reduction of the analog depth of the synaptic variable also makes this solution appealing from the point of view of electronic implementation and offers a simple methodological alternative to the technological solution based on floating gates. We describe the full custom analog very large-scale integration (VLSI) realization of a small network of integrate-and-fire neurons connected by bistable deterministic plastic synapses which can implement the idea of stochastic learning. In the absence of stimuli, the memory is preserved indefinitely. During the stimulation the synapse undergoes quick temporary changes through the activities of the pre- and postsynaptic neurons; those changes stochastically result in a long-term modification of the synaptic efficacy. The intentionally disordered pattern of connectivity allows the system to generate a randomness suited to drive the stochastic selection mechanism. We check by a suitable stimulation protocol that the stochastic synaptic plasticity produces the expected pattern of potentiation and depression in the electronic network.

Modeling the effects of trophy selection and environmental disturbance on a simulated population of African lions.

PubMed

Whitman, Karyl L; Starfield, Anthony M; Quadling, Henley; Packer, Craig

2007-06-01

Tanzania is a premier destination for trophy hunting of African lions (Panthera leo) and is home to the most extensive long-term study of unhunted lions. Thus, it provides a unique opportunity to apply data from a long-term field study to a conservation dilemma: How can a trophy-hunted species whose reproductive success is closely tied to social stability be harvested sustainably? We used an individually based, spatially explicit, stochastic model, parameterized with nearly 40 years of behavioral and demographic data on lions in the Serengeti, to examine the separate effects of trophy selection and environmental disturbance on the viability of a simulated lion population in response to annual harvesting. Female population size was sensitive to the harvesting of young males (> or = 3 years), whereas hunting represented a relatively trivial threat to population viability when the harvest was restricted to mature males (> or = 6 years). Overall model performance was robust to environmental disturbance and to errors in age assessment based on nose coloration as an index used to age potential trophies. Introducing an environmental disturbance did not eliminate the capacity to maintain a viable breeding population when harvesting only older males, and initially depleted populations recovered within 15-25 years after the disturbance to levels comparable to hunted populations that did not experience a catastrophic event. These results are consistent with empirical observations of lion resilience to environmental stochasticity.

Long-term outcomes following plate stabilization to address spontaneous luxation of the long digital extensor tendon of origin in 2 dogs.

PubMed

Hasiuk, Michelle M M; Drygas, Kevin A; Lewis, Daniel D

2017-11-01

Two dogs with spontaneous luxation of the long digital extensor tendon of origin were managed by performing a sulcoplasty and applying a plate bridging the extensor sulcus. Lameness resolved and neither dog had recurrence of lameness 59 and 15 months following surgery.

Walking with a four wheeled walker (rollator) significantly reduces EMG lower-limb muscle activity in healthy subjects.

PubMed

Suica, Zorica; Romkes, Jacqueline; Tal, Amir; Maguire, Clare

2016-01-01

To investigate the immediate effect of four-wheeled- walker(rollator)walking on lower-limb muscle activity and trunk-sway in healthy subjects. In this cross-sectional design electromyographic (EMG) data was collected in six lower-limb muscle groups and trunk-sway was measured as peak-to-peak angular displacement of the centre-of-mass (level L2/3) in the sagittal and frontal-planes using the SwayStar balance system. 19 subjects walked at self-selected speed firstly without a rollator then in randomised order 1. with rollator 2. with rollator with increased weight-bearing. Rollator-walking caused statistically significant reductions in EMG activity in lower-limb muscle groups and effect-sizes were medium to large. Increased weight-bearing increased the effect. Trunk-sway in the sagittal and frontal-planes showed no statistically significant difference between conditions. Rollator-walking reduces lower-limb muscle activity but trunk-sway remains unchanged as stability is likely gained through forces generated by the upper-limbs. Short-term stability is gained but the long-term effect is unclear and requires investigation. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Bonded functional esthetic prototype: an alternative pre-treatment mock-up technique and cost-effective medium-term esthetic solution.

PubMed

McLaren, Edward A

2013-09-01

As the economy has receded in recent years, many patients have been inclined to reject dental treatment beyond what they feel is the minimal amount necessary. Increasingly, there has been reluctance to take on the expense of full-mouth restorations and time-consuming procedures. Consequently, clinicians can benefit from innovative, conservative, interim solutions that enable them to provide segment treatment with long-term stability and esthetics, with lower initial cost. The bonded functional esthetic prototype (BFEP) allows fabrication of up to 14 teeth from composite in 1 hour, providing either a pre-treatment restoration or a long-term provisional solution until further treatment can be completed. As demonstrated herein, the BFEP enables superb function, stability, and esthetics in the interim while dispersing the cost of definitive treatment over time.

Long-term physical and oxidative stability of liposomes containing glycerides of lipoic acid

USDA-ARS?s Scientific Manuscript database

The acyl glycerides of lipoic and dihydrolipoic acids may serve as slow-release sources for cutaneous delivery of these antioxidants when formulated in a liposomal vehicle. Accelerated storage testing was conducted to determine the storage stability of the lipoic derivatives and of the soybean phosp...

Long term stability of microbial diversity and activity potential in severely disturbed arid lands of the southwest

USDA-ARS?s Scientific Manuscript database

Arid land cryptobiotic soil crusts govern water infiltration, soil aggregate stability and nutrient cycling between soil microbial communities and vascular plants. Surface mining involves removal of topsoil and associated crust and storage in mixed mounds for extended periods. The exposed subsoil an...

Concurrent and Long-Term Impact of Intimate Partner Violence on Employment Stability

ERIC Educational Resources Information Center

Crowne, Sarah Shea; Juon, Hee-Soon; Ensminger, Margaret; Burrell, Lori; McFarlane, Elizabeth; Duggan, Anne

2011-01-01

Previous research suggests that experiencing intimate partner violence (IPV) may negatively affect employment outcomes. This study explores the relationship between IPV and employment stability both concurrently and longitudinally among a sample of 512 predominantly Asian American and Pacific Islander young women living in Hawaii. Women in this…

Stability of Behavioral Ratings of Children with SLI.

ERIC Educational Resources Information Center

Redmond, Sean M.; Rice, Mabel L.

2002-01-01

A study investigated the long-term stability of the teacher and parent behavioral ratings of 37 children with specific language impairment. Results indicate diminishment in teacher-reported behavior problems in most areas of socioemotional development from kindergarten to second grade and increasing congruence between teacher and parent ratings.…

Stabilizing Group Treatment for Complex Posttraumatic Stress Disorder Related to Childhood Abuse Based on Psycho-Education and Cognitive Behavioral Therapy: A Pilot Study

ERIC Educational Resources Information Center

Dorrepaal, Ethy; Thomaes, Kathleen; Smit, Johannes H.; van Balkom, Anton J. L. M.; van Dyck, Richard; Veltman, Dick J.; Draijer, Nel

2010-01-01

Objective: This study tests a Stabilizing Group Treatment protocol, designed for the management of the long-term sequelae of child abuse, that is, Complex Posttraumatic Stress Disorder (Complex PTSD). Evidence-based treatment for this subgroup of PTSD patients is largely lacking. This stabilizing treatment aims at improving Complex PTSD using…

An inexpensive and stable LED Sun photometer for measuring the water vapor column over South Texas from 1990 to 2001

NASA Astrophysics Data System (ADS)

Mims, Forrest M.

2002-07-01

A Sun photometer that uses near-infrared light-emitting diodes (LEDs) as spectrally-selective photodetectors has measured total column water vapor in South Texas since February 1990. The 12 years of solar noon observations to date are correlated with upper air soundings at Del Rio, Texas (r2 = 0.75), and highly correlated with measurements by a Microtops II filter Sun photometer (r2 = 0.94). LEDs are inexpensive and have far better long term stability than the interference filters in conventional Sun photometers. The LED Sun photometer therefore provides an inexpensive, stable and portable means for measuring column water vapor.

Investigation of the leaching behavior of lead in stabilized/solidified waste using a two-year semi-dynamic leaching test.

PubMed

Xue, Qiang; Wang, Ping; Li, Jiang-Shan; Zhang, Ting-Ting; Wang, Shan-Yong

2017-01-01

Long-term leaching behavior of contaminant from stabilization/solidification (S/S) treated waste stays unclear. For the purpose of studying long-term leaching behavior and leaching mechanism of lead from cement stabilized soil under different pH environment, semi-dynamic leaching test was extended to two years to investigate leaching behaviors of S/S treated lead contaminated soil. Effectiveness of S/S treatment in different scenarios was evaluated by leachability index (LX) and effective diffusion coefficient (D e ). In addition, the long-term leaching mechanism was investigated at different leaching periods. Results showed that no significant difference was observed among the values of the cumulative release of Pb, D e and LX in weakly alkaline and weakly acidic environment (pH value varied from 5.00 to 10.00), and all the controlling leaching mechanisms of the samples immersed in weakly alkaline and weakly acidic environments turned out to be diffusion. Strong acid environment would significantly affect the leaching behavior and leaching mechanism of lead from S/S monolith. The two-year variation of D e appeared to be time dependent, and D e values increased after the 210 th day in weakly alkaline and weakly acidic environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol

NASA Astrophysics Data System (ADS)

Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

2016-12-01

Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5-2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared.

Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol

PubMed Central

Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

2016-01-01

Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5–2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared. PMID:27958366

Advances in Patellofemoral Arthroplasty.

PubMed

Strickland, Sabrina M; Bird, Mackenzie L; Christ, Alexander B

2018-06-01

To describe current indications, implants, economic benefits, comparison to TKA, and functional and patient-reported outcomes of patellofemoral arthroplasty. Modern onlay implants and improved patient selection have allowed for recent improvements in short- and long-term outcomes after patellofemoral joint replacement surgery. Patellofemoral arthroplasty has become an increasingly utilized technique for the successful treatment of isolated patellofemoral arthritis. Advances in patient selection, implant design, and surgical technique have resulted in improved performance and longevity of these implants. Although short- and mid-term data for modern patellofemoral arthroplasties appear promising, further long-term clinical studies are needed to evaluate how new designs and technologies will affect patient outcomes and long-term implant performance.

Cryopreservation of MHC multimers: Recommendations for quality assurance in detection of antigen specific T cells.

PubMed

Hadrup, Sine Reker; Maurer, Dominik; Laske, Karoline; Frøsig, Thomas Mørch; Andersen, Sofie Ramskov; Britten, Cedrik M; van der Burg, Sjoerd H; Walter, Steffen; Gouttefangeas, Cécile

2015-01-01

Fluorescence-labeled peptide-MHC class I multimers serve as ideal tools for the detection of antigen-specific T cells by flow cytometry, enabling functional and phenotypical characterization of specific T cells at the single cell level. While this technique offers a number of unique advantages, MHC multimer reagents can be difficult to handle in terms of stability and quality assurance. The stability of a given fluorescence-labeled MHC multimer complex depends on both the stability of the peptide-MHC complex itself and the stability of the fluorochrome. Consequently, stability is difficult to predict and long-term storage is generally not recommended. We investigated here the possibility of cryopreserving MHC multimers, both in-house produced and commercially available, using a wide range of peptide-MHC class I multimers comprising virus and cancer-associated epitopes of different affinities presented by various HLA-class I molecules. Cryopreservation of MHC multimers was feasible for at least 6 months, when they were dissolved in buffer containing 5-16% glycerol (v/v) and 0.5% serum albumin (w/v). The addition of cryoprotectants was tolerated across three different T-cell staining protocols for all fluorescence labels tested (PE, APC, PE-Cy7 and Quantum dots). We propose cryopreservation as an easily implementable method for stable storage of MHC multimers and recommend the use of cryopreservation in long-term immunomonitoring projects, thereby eliminating the variability introduced by different batches and inconsistent stability. © 2014 International Society for Advancement of Cytometry.

Cryopreservation of MHC Multimers: Recommendations for Quality Assurance in Detection of Antigen Specific T Cells

PubMed Central

Hadrup, Sine Reker; Maurer, Dominik; Laske, Karoline; Frøsig, Thomas Mørch; Andersen, Sofie Ramskov; Britten, Cedrik M; van der Burg, Sjoerd H; Walter, Steffen; Gouttefangeas, Cécile

2015-01-01

Fluorescence-labeled peptide-MHC class I multimers serve as ideal tools for the detection of antigen-specific T cells by flow cytometry, enabling functional and phenotypical characterization of specific T cells at the single cell level. While this technique offers a number of unique advantages, MHC multimer reagents can be difficult to handle in terms of stability and quality assurance. The stability of a given fluorescence-labeled MHC multimer complex depends on both the stability of the peptide-MHC complex itself and the stability of the fluorochrome. Consequently, stability is difficult to predict and long-term storage is generally not recommended. We investigated here the possibility of cryopreserving MHC multimers, both in-house produced and commercially available, using a wide range of peptide-MHC class I multimers comprising virus and cancer-associated epitopes of different affinities presented by various HLA-class I molecules. Cryopreservation of MHC multimers was feasible for at least 6 months, when they were dissolved in buffer containing 5–16% glycerol (v/v) and 0.5% serum albumin (w/v). The addition of cryoprotectants was tolerated across three different T-cell staining protocols for all fluorescence labels tested (PE, APC, PE-Cy7 and Quantum dots). We propose cryopreservation as an easily implementable method for stable storage of MHC multimers and recommend the use of cryopreservation in long-term immunomonitoring projects, thereby eliminating the variability introduced by different batches and inconsistent stability. © 2014 International Society for Advancement of Cytometry PMID:25297339

Improvement of a stability-indicating method by Quality-by-Design versus Quality-by-Testing: a case of a learning process.

PubMed

Hubert, C; Lebrun, P; Houari, S; Ziemons, E; Rozet, E; Hubert, Ph

2014-01-01

The understanding of the method is a major concern when developing a stability-indicating method and even more so when dealing with impurity assays from complex matrices. In the presented case study, a Quality-by-Design approach was applied in order to optimize a routinely used method. An analytical issue occurring at the last stage of a long-term stability study involving unexpected impurities perturbing the monitoring of characterized impurities needed to be resolved. A compliant Quality-by-Design (QbD) methodology based on a Design of Experiments (DoE) approach was evaluated within the framework of a Liquid Chromatography (LC) method. This approach allows the investigation of Critical Process Parameters (CPPs), which have an impact on Critical Quality Attributes (CQAs) and, consequently, on LC selectivity. Using polynomial regression response modeling as well as Monte Carlo simulations for error propagation, Design Space (DS) was computed in order to determine robust working conditions for the developed stability-indicating method. This QbD compliant development was conducted in two phases allowing the use of the Design Space knowledge acquired during the first phase to define the experimental domain of the second phase, which constitutes a learning process. The selected working condition was then fully validated using accuracy profiles based on statistical tolerance intervals in order to evaluate the reliability of the results generated by this LC/ESI-MS stability-indicating method. A comparison was made between the traditional Quality-by-Testing (QbT) approach and the QbD strategy, highlighting the benefit of this QbD strategy in the case of an unexpected impurities issue. On this basis, the advantages of a systematic use of the QbD methodology were discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Size-Controlled Synthesis of Sub-10 nm PtNi3 Alloy Nanoparticles and their Unusual Volcano-Shaped Size Effect on ORR Electrocatalysis.

PubMed

Gan, Lin; Rudi, Stefan; Cui, Chunhua; Heggen, Marc; Strasser, Peter

2016-06-01

Dealloyed Pt bimetallic core-shell catalysts derived from low-Pt bimetallic alloy nanoparticles (e.g, PtNi3 ) have recently shown unprecedented activity and stability on the cathodic oxygen reduction reaction (ORR) under realistic fuel cell conditions and become today's catalyst of choice for commercialization of automobile fuel cells. A critical step toward this breakthrough is to control their particle size below a critical value (≈10 nm) to suppress nanoporosity formation and hence reduce significant base metal (e.g., Ni) leaching under the corrosive ORR condition. Fine size control of the sub-10 nm PtNi3 nanoparticles and understanding their size dependent ORR electrocatalysis are crucial to further improve their ORR activity and stability yet still remain unexplored. A robust synthetic approach is presented here for size-controlled PtNi3 nanoparticles between 3 and 10 nm while keeping a constant particle composition and their size-selected growth mechanism is studied comprehensively. This enables us to address their size-dependent ORR activities and stabilities for the first time. Contrary to the previously established monotonic increase of ORR specific activity and stability with increasing particle size on Pt and Pt-rich bimetallic nanoparticles, the Pt-poor PtNi3 nanoparticles exhibit an unusual "volcano-shaped" size dependence, showing the highest ORR activity and stability at the particle sizes between 6 and 8 nm due to their highest Ni retention during long-term catalyst aging. The results of this study provide important practical guidelines for the size selection of the low Pt bimetallic ORR electrocatalysts with further improved durably high activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mid- and long-term runoff predictions by an improved phase-space reconstruction model.

PubMed

Hong, Mei; Wang, Dong; Wang, Yuankun; Zeng, Xiankui; Ge, Shanshan; Yan, Hengqian; Singh, Vijay P

2016-07-01

In recent years, the phase-space reconstruction method has usually been used for mid- and long-term runoff predictions. However, the traditional phase-space reconstruction method is still needs to be improved. Using the genetic algorithm to improve the phase-space reconstruction method, a new nonlinear model of monthly runoff is constructed. The new model does not rely heavily on embedding dimensions. Recognizing that the rainfall-runoff process is complex, affected by a number of factors, more variables (e.g. temperature and rainfall) are incorporated in the model. In order to detect the possible presence of chaos in the runoff dynamics, chaotic characteristics of the model are also analyzed, which shows the model can represent the nonlinear and chaotic characteristics of the runoff. The model is tested for its forecasting performance in four types of experiments using data from six hydrological stations on the Yellow River and the Yangtze River. Results show that the medium-and long-term runoff is satisfactorily forecasted at the hydrological stations. Not only is the forecasting trend accurate, but also the mean absolute percentage error is no more than 15%. Moreover, the forecast results of wet years and dry years are both good, which means that the improved model can overcome the traditional ''wet years and dry years predictability barrier,'' to some extent. The model forecasts for different regions are all good, showing the universality of the approach. Compared with selected conceptual and empirical methods, the model exhibits greater reliability and stability in the long-term runoff prediction. Our study provides a new thinking for research on the association between the monthly runoff and other hydrological factors, and also provides a new method for the prediction of the monthly runoff. Copyright © 2015 Elsevier Inc. All rights reserved.

Phosphorus immobilization in micropores of drinking-water treatment residuals: implications for long-term stability.

PubMed

Makris, Konstantinos C; Harris, Willie G; O'Connor, George A; Obreza, Thomas A

2004-12-15

Drinking-water treatment residuals (WTRs) can immobilize excess soil phosphorus (P), but little is known about the long-term P retention by WTRs. To evaluate the long-term P sorption characteristics of one Fe- and one Al-based WTR, physicochemical properties pertinent to time-dependency and hysteresis of P sorption were assessed. This study also investigated the P sorption mechanisms that could affect the long-term stability of sorbed P by WTRs. Phosphorus sorption kinetics by the WTRs exhibited a slow phase that followed an initial rapid phase, as typically occurs with metal hydroxides. Phosphorus sorption maxima for both Fe- and Al-based WTRs exceeded 9100 mg of P kg(-1) and required a greater specific surface area (SSA) than would be available based on BET-N2 calculations. Electron microprobe analyses of cross-sectional, P-treated particles showed three-dimensional P sorption by WTRs. Carbon dioxide gas sorption was greater than N2, suggesting steric restriction of N2 diffusion by narrow micropore openings. Phosphorus-treated Co2 SSAs were reduced by P treatment, suggesting P sorption by micropores (5-20 A). Mercury intrusion porosimetry indicated negligible macroporosity (pores > 500 A). Slow P sorption kinetics by WTRs may be explained by intraparticle P diffusion in micropores. Micropore-bound P should be stable and immobilized over long periods.

Long-Term Stability of Residual Stress Improvement by Water Jet Peening Considering Working Processes.

PubMed

Hashimoto, Tadafumi; Osawa, Yusuke; Itoh, Shinsuke; Mochizuki, Masahito; Nishimoto, Kazutoshi

2013-06-01

To prevent primary water stress corrosion cracking (PWSCC), water jet peening (WJP) has been used on the welds of Ni-based alloys in pressurized water reactors (PWRs). Before WJP, the welds are machined and buffed in order to conduct a penetrant test (PT) to verify the weld qualities to access, and microstructure evolution takes place in the target area due to the severe plastic deformation. The compressive residual stresses induced by WJP might be unstable under elevated temperatures because of the high dislocation density in the compressive stress layer. Therefore, the stability of the compressive residual stresses caused by WJP was investigated during long-term operation by considering the microstructure evolution due to the working processes. The following conclusions were made: The compressive residual stresses were slightly relaxed in the surface layers of the thermally aged specimens. There were no differences in the magnitude of the relaxation based on temperature or time. The compressive residual stresses induced by WJP were confirmed to remain stable under elevated temperatures. The stress relaxation at the surface followed the Johnson-Mehl equation, which states that stress relaxation can occur due to the recovery of severe plastic strain, since the estimated activation energy agrees very well with the self-diffusion energy for Ni. By utilizing the additivity rule, it was indicated that stress relaxation due to recovery is completed during the startup process. It was proposed that the long-term stability of WJP under elevated temperatures must be assessed based on compressive stresses with respect to the yield stress. Thermal elastic-plastic creep analysis was performed to predict the effect of creep strain. After 100 yr of simulated continuous operation at 80% capacity, there was little change in the WJP compressive stresses under an actual operating temperature of 623 K. Therefore, the long-term stability of WJP during actual operation was analytically predicted.

The role of opacity and transparency in achieving strategic stability in South Asia.

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

Rajain, Arpit; Ashraf, Tariq Mahmud

According to international relations theory, deterrence can be used as a tool to achieve stability between potentially hostile nations. India and Pakistan's long history of periodic crises raises the question of how they can achieve deterrence stability. 'Transparency' describes the flow of information between parties and plays a key role in establishing a deterrence relationship. This paper studies the balance needed between opacity and transparency in nuclear topics for the maintenance of deterrence stability between India and Pakistan. States with nuclear weapons are postulated to implement transparency in four categories: potential, capability, intent, and resolve. The study applies these categoriesmore » to the nuclear components of the ongoing India-Pakistan Composite Dialogue Working Group for Peace and Security including CBMs. To focus our efforts, we defined four scenarios to characterize representative strategic/military/political conditions. The scenarios are combinations of these two sets of opposite poles: competition - cooperation; extremism - moderation (to be understood primarily in a religious/nationalistic sense). We describe each scenario in terms of select focal areas (nuclear doctrine, nuclear command and control, nuclear stockpile, nuclear delivery/defensive systems, and conventional force posture). The scenarios help frame the realm of possibilities, and have been described in terms of expected conditions for the focal areas. We then use the conditions in each scenario to prescribe a range of information-sharing actions that the two countries could take to increase stability. We also highlight the information that should not be shared. These actions can be political (e.g., declarations), procedural (e.g., advance notice of certain military activities), or technologically based (e.g., seismic monitoring of the nuclear test moratorium).« less

Two-stage system based on a software-defined radio for stabilizing of optical frequency combs in long-term experiments.

PubMed

Cížek, Martin; Hucl, Václav; Hrabina, Jan; Smíd, Radek; Mikel, Břetislav; Lazar, Josef; Cíp, Ondřej

2014-01-20

A passive optical resonator is a special sensor used for measurement of lengths on the nanometer and sub-nanometer scale. A stabilized optical frequency comb can provide an ultimate reference for measuring the wavelength of a tunable laser locked to the optical resonator. If we lock the repetition and offset frequencies of the comb to a high-grade radiofrequency (RF) oscillator its relative frequency stability is transferred from the RF to the optical frequency domain. Experiments in the field of precise length metrology of low-expansion materials are usually of long-term nature so it is required that the optical frequency comb stay in operation for an extended period of time. The optoelectronic closed-loop systems used for stabilization of combs are usually based on traditional analog electronic circuits processing signals from photodetectors. From an experimental point of view, these setups are very complicated and sensitive to ambient conditions, especially in the optical part, therefore maintaining long-time operation is not easy. The research presented in this paper deals with a novel approach based on digital signal processing and a software-defined radio. We describe digital signal processing algorithms intended for keeping the femtosecond optical comb in a long-time stable operation. This need arose during specialized experiments involving measurements of optical frequencies of tunable continuous-wave lasers. The resulting system is capable of keeping the comb in lock for an extensive period of time (8 days or more) with the relative stability better than 1.6 × 10(-11).

Structure, corrosion behavior and mechanical property of a novel poly(vinyl alcohol) composite in simulated body fluid.

PubMed

Li, Juan; Suo, Jinping; Zou, Peng; Jia, Lintao; Wang, Shifang

2010-01-01

The data for long-term drug-delivery systems are scarce compared to the short-term systems because the required research efforts are more time-consuming. In this study, we report a novel cross-linked composite based on poly(vinyl alcohol) (PVA) containing cupric ions for long-term delivery, which is helpful for contraception and trace element balance in the human body. The composition, corrosion products, crystal structure, chemical structure and mechanical stability of the composite, after being immersed in simulated body fluid (SBF) for one year, were studied by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR) and mechanical testing. The results show that no other new elements, such as P, Cl and Ca, appear on the surface of the composite and no Cu(2)O was formed after immersion in SBF for one year. The effectiveness of copper can be greatly improved and the side-effects caused by these compounds might also be eliminated. Furthermore, this novel composite exhibits long-term mechanical stability in SBF. The present in vitro long-term data suggest that this novel copper-containing composite may serve as a substitute for conventional materials of copper-containing intrauterine devices (Cu-IUDs) and as a carrier for controlled-release material in a variety of other applications.

Immersion-scanning-tunneling-microscope for long-term variable-temperature experiments at liquid-solid interfaces

NASA Astrophysics Data System (ADS)

Ochs, Oliver; Heckl, Wolfgang M.; Lackinger, Markus

2018-05-01

Fundamental insights into the kinetics and thermodynamics of supramolecular self-assembly on surfaces are uniquely gained by variable-temperature high-resolution Scanning-Tunneling-Microscopy (STM). Conventionally, these experiments are performed with standard ambient microscopes extended with heatable sample stages for local heating. However, unavoidable solvent evaporation sets a technical limit on the duration of these experiments, hence prohibiting long-term experiments. These, however, would be highly desirable to provide enough time for temperature stabilization and settling of drift but also to study processes with inherently slow kinetics. To overcome this dilemma, we propose a STM that can operate fully immersed in solution. The instrument is mounted onto the lid of a hermetically sealed heatable container that is filled with the respective solution. By closing the container, both the sample and microscope are immersed in solution. Thereby solvent evaporation is eliminated and an environment for long-term experiments with utmost stable and controllable temperatures between room-temperature and 100 °C is provided. Important experimental requirements for the immersion-STM and resulting design criteria are discussed, the strategy for protection against corrosive media is described, the temperature stability and drift behavior are thoroughly characterized, and first long-term high resolution experiments at liquid-solid interfaces are presented.

Cellular Ti-6Al-4V structures with interconnected macro porosity for bone implants fabricated by selective electron beam melting.

PubMed

Heinl, Peter; Müller, Lenka; Körner, Carolin; Singer, Robert F; Müller, Frank A

2008-09-01

Selective electron beam melting (SEBM) was successfully used to fabricate novel cellular Ti-6Al-4V structures for orthopaedic applications. Micro computer tomography (microCT) analysis demonstrated the capability to fabricate three-dimensional structures with an interconnected porosity and pore sizes suitable for tissue ingrowth and vascularization. Mechanical properties, such as compressive strength and elastic modulus, of the tested structures were similar to those of human bone. Thus, stress-shielding effects after implantation might be avoided due to a reduced stiffness mismatch between implant and bone. A chemical surface modification using HCl and NaOH induced apatite formation during in vitro bioactivity tests in simulated body fluid under dynamic conditions. The modified bioactive surface is expected to enhance the fixation of the implant in the surrounding bone as well as to improve its long-term stability.

A Room Temperature Nitric Oxide Gas Sensor Based on a Copper-Ion-Doped Polyaniline/Tungsten Oxide Nanocomposite

PubMed Central

Wang, Shih-Han; Shen, Chi-Yen; Su, Jian-Ming; Chang, Shiang-Wen

2015-01-01

The parts-per-billion-level nitric oxide (NO) gas sensing capability of a copper-ion-doped polyaniline/tungsten oxide nanocomposite (Cu2+/PANI/WO3) film coated on a Rayleigh surface acoustic wave device was investigated. The sensor developed in this study was sensitive to NO gas at room temperature in dry nitrogen. The surface morphology, dopant distribution, and electric properties were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and Hall effect measurements, respectively. The Cu2+/PANI/WO3 film exhibited high NO gas sensitivity and selectivity as well as long-term stability. At 1 ppb of NO, a signal with a frequency shift of 4.3 ppm and a signal-to-noise ratio of 17 was observed. The sensor exhibited distinct selectivity toward NO gas with no substantial response to O2, NH3 and CO2 gases. PMID:25811223

Monitoring technologies for ocean disposal of radioactive waste

NASA Astrophysics Data System (ADS)

Triplett, M. B.; Solomon, K. A.; Bishop, C. B.; Tyce, R. C.

1982-01-01

The feasibility of using carefully selected subseabed locations to permanently isolate high level radioactive wastes at ocean depths greater than 4000 meters is discussed. Disposal at several candidate subseabed areas is being studied because of the long term geologic stability of the sediments, remoteness from human activity, and lack of useful natural resources. While the deep sea environment is remote, it also poses some significant challenges for the technology required to survey and monitor these sites, to identify and pinpoint container leakage should it occur, and to provide the environmental information and data base essential to determining the probable impacts of any such occurrence. Objectives and technical approaches to aid in the selective development of advanced technologies for the future monitoring of nuclear low level and high level waste disposal in the deep seabed are presented. Detailed recommendations for measurement and sampling technology development needed for deep seabed nuclear waste monitoring are also presented.

Graphene Oxide Sponge as Nanofillers in Printable Electrolytes in High-Performance Quasi-Solid-State Dye-Sensitized Solar Cells.

PubMed

Venkatesan, Shanmuganathan; Surya Darlim, Elmer; Tsai, Ming-Hsiang; Teng, Hsisheng; Lee, Yuh-Lang

2018-04-04

A graphene oxide sponge (GOS) is utilized for the first time as a nanofiller (NF) in printable electrolytes (PEs) based on poly(ethylene oxide) and poly(vinylidene fluoride) for quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The effects of the various concentrations of GOS NFs on the ion diffusivity and conductivity of electrolytes and the performance of the QS-DSSCs are studied. The results show that the presence of GOS NFs significantly increases the diffusivity and conductivity of the PEs. The introduction of 1.5 wt % of GOS NFs decreases the charge-transfer resistance at the Pt-counter electrode/electrolyte interface ( R pt ) and increases the recombination resistance at the photoelectrode/electrolyte interface ( R ct ). QS-DSSC utilizing 1.5 wt % GOS NFs can achieve an energy conversion efficiency (8.78%) higher than that found for their liquid counterpart and other reported polymer gel electrolytes/GO NFs based DSSCs. The high energy conversion efficiency is a consequence of the increase in both the open-circuit potential ( V oc ) and fill factor with a slight decrease in current density ( J sc ). The cell efficiency can retain 86% of its initial value after a 500 h stability test at 60 °C under dark conditions. The long-term stability of the QS-DSSC with GOS NFs is higher than that without NFs. This result indicates that the GOS NFs do not cause dye-desorption from the photoanode in a long-term stability test, which infers a superior performance of GOS NFs as compared to TiO 2 NFs in terms of increasing the efficiency and long-term stability of QS-DSSCs.

Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells.

PubMed

Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Ieropoulos, Ioannis

2013-11-01

The long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability. Copyright © 2013 Elsevier Ltd. All rights reserved.

Super long-life supercapacitors based on the construction of nanohoneycomb-like strongly coupled CoMoO(4)-3D graphene hybrid electrodes.

PubMed

Yu, Xinzhi; Lu, Bingan; Xu, Zhi

2014-02-01

Nanohoneycomb-like strongly coupled CoMoO4 -3D graphene hybird electrodes are synthesized for supercapacitors which exhibit excellent specific capacitance and superior long-term cycle stability. The supercapacitor device can power a 5 mm-diameter LED efficiently for more than 3 min with a charging time of only 2 s, and shows high energy densities and good cycle stability. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinematic variability, fractal dynamics and local dynamic stability of treadmill walking

PubMed Central

2011-01-01

Background Motorized treadmills are widely used in research or in clinical therapy. Small kinematics, kinetics and energetics changes induced by Treadmill Walking (TW) as compared to Overground Walking (OW) have been reported in literature. The purpose of the present study was to characterize the differences between OW and TW in terms of stride-to-stride variability. Classical (Standard Deviation, SD) and non-linear (fractal dynamics, local dynamic stability) methods were used. In addition, the correlations between the different variability indexes were analyzed. Methods Twenty healthy subjects performed 10 min TW and OW in a random sequence. A triaxial accelerometer recorded trunk accelerations. Kinematic variability was computed as the average SD (MeanSD) of acceleration patterns among standardized strides. Fractal dynamics (scaling exponent α) was assessed by Detrended Fluctuation Analysis (DFA) of stride intervals. Short-term and long-term dynamic stability were estimated by computing the maximal Lyapunov exponents of acceleration signals. Results TW did not modify kinematic gait variability as compared to OW (multivariate T2, p = 0.87). Conversely, TW significantly modified fractal dynamics (t-test, p = 0.01), and both short and long term local dynamic stability (T2 p = 0.0002). No relationship was observed between variability indexes with the exception of significant negative correlation between MeanSD and dynamic stability in TW (3 × 6 canonical correlation, r = 0.94). Conclusions Treadmill induced a less correlated pattern in the stride intervals and increased gait stability, but did not modify kinematic variability in healthy subjects. This could be due to changes in perceptual information induced by treadmill walking that would affect locomotor control of the gait and hence specifically alter non-linear dependencies among consecutive strides. Consequently, the type of walking (i.e. treadmill or overground) is important to consider in each protocol design. PMID:21345241

Memory T and memory B cells share a transcriptional program of self-renewal with long-term hematopoietic stem cells

PubMed Central

Luckey, Chance John; Bhattacharya, Deepta; Goldrath, Ananda W.; Weissman, Irving L.; Benoist, Christophe; Mathis, Diane

2006-01-01

The only cells of the hematopoietic system that undergo self-renewal for the lifetime of the organism are long-term hematopoietic stem cells and memory T and B cells. To determine whether there is a shared transcriptional program among these self-renewing populations, we first compared the gene-expression profiles of naïve, effector and memory CD8+ T cells with those of long-term hematopoietic stem cells, short-term hematopoietic stem cells, and lineage-committed progenitors. Transcripts augmented in memory CD8+ T cells relative to naïve and effector T cells were selectively enriched in long-term hematopoietic stem cells and were progressively lost in their short-term and lineage-committed counterparts. Furthermore, transcripts selectively decreased in memory CD8+ T cells were selectively down-regulated in long-term hematopoietic stem cells and progressively increased with differentiation. To confirm that this pattern was a general property of immunologic memory, we turned to independently generated gene expression profiles of memory, naïve, germinal center, and plasma B cells. Once again, memory-enriched and -depleted transcripts were also appropriately augmented and diminished in long-term hematopoietic stem cells, and their expression correlated with progressive loss of self-renewal function. Thus, there appears to be a common signature of both up- and down-regulated transcripts shared between memory T cells, memory B cells, and long-term hematopoietic stem cells. This signature was not consistently enriched in neural or embryonic stem cell populations and, therefore, appears to be restricted to the hematopoeitic system. These observations provide evidence that the shared phenotype of self-renewal in the hematopoietic system is linked at the molecular level. PMID:16492737

Cervarix, the GSK HPV-16/HPV-18 AS04-adjuvanted cervical cancer vaccine, demonstrates stability upon long-term storage and under simulated cold chain break conditions.

PubMed

Le Tallec, David; Doucet, Diane; Elouahabi, Abdelatif; Harvengt, Pol; Deschuyteneer, Michel; Deschamps, Marguerite

2009-07-01

Cervarix is a recombinant human papillomavirus (HPV)-16 and -18 L1 virus-like-particle (VLP) AS04-adjuvanted vaccine designed to protect against cervical intraepithelial neoplasia and cervical cancer caused by the HPV types 16 and 18. Assessment of the stability of the vaccine during long-term storage and after transient exposure to temperatures out of normal storage range is an integrated part of vaccine quality evaluation. This assessment was done with vaccine samples stored at 2-8 degrees C for up to 36 months, with or without simulated cold chain break (either one week at 37 degrees C, or two or four weeks at 25 degrees C). Among the stability-indicating parameters, antigenicity and immunogenicity were evaluated along with L1 antigen integrity and adsorption to aluminum. Differential scanning calorimetry (DSC) was used to investigate the structural stability of the VLPs before and after vaccine formulation and over time. Cervarix was stable at 2-8 degrees C for at least three years, and the occurrence of cold chain break had no impact, as shown by unchanged product characteristics during the full storage period. DSC analysis demonstrated that the structure of the HPV-16 and -18 L1 proteins and their corresponding VLPs was not affected throughout the manufacturing process. Moreover, the structure of aluminum-adsorbed HPV-16 and -18 L1 VLPs was robust over a 14-month test period. In conclusion, Cervarix was very stable upon long-term storage at 2-8 degrees C with or without transient exposure to higher temperatures (up to 37 degrees C). The observed robust structure of the L1 VLPs contributes to the excellent stability of Cervarix.

Novel cell-based odorant sensor elements based on insect odorant receptors.

PubMed

Mitsuno, Hidefumi; Sakurai, Takeshi; Namiki, Shigehiro; Mitsuhashi, Hiroyuki; Kanzaki, Ryohei

2015-03-15

Development of cell-based odorant sensor elements combined not only high degree of sensitivity and selectivity but also long-term stability is crucial for their practical applications. Here we report the development of a novel cell-based odorant sensor element that sensitively and selectively detects odorants and displays increased fluorescent intensities over a long period of time. Our odorant sensor elements, based on Sf21 cell lines expressing insect odorant receptors, are sensitive to the level of several tens of parts per billion in solution, can selectively distinguish between different types of odorants based on the odorant selectivity intrinsic to the expressed receptors, and have response times of approximately 13s. Specifically, with the use of Sf21 cells and insect odorant receptors, we demonstrated that the established cell lines stably expressing insect odorant receptors are able to detect odorants with consistent responsiveness for at least 2 months, thus exceeding the short life-span normally associated with cell-based sensors. We also demonstrated the development of a compact odorant sensor chip by integrating the established insect cell lines into a microfluidic chip. The methodology we established in this study, in conjunction with the large repertoire of insect odorant receptors, will aid in the development of practical cell-based odorant sensors for various applications, including food administration and health management. Copyright © 2014 Elsevier B.V. All rights reserved.

Long-term urethral catheterisation.

PubMed

Turner, Bruce; Dickens, Nicola

This article discusses long-term urethral catheterisation, focusing on the relevant anatomy and physiology, indications for the procedure, catheter selection and catheter care. It is important that nurses have a good working knowledge of long-term catheterisation as the need for this intervention will increase with the rise in chronic health conditions and the ageing population.

Curcumin-loaded lipid nanocarrier for improving bioavailability, stability and cytotoxicity against malignant glioma cells.

PubMed

Kumar, Anil; Ahuja, Alka; Ali, Javed; Baboota, Sanjula

2016-01-01

In the present study, Curcumin (CU)-loaded nanocarrier (NC) such as nanoemulsion (NE) was developed with the objective of increasing its cytotoxicity and bioavailability through lymphatic transport by enhancing its solubility and intestinal permeability. Based on the area obtained in pseudoternary phase diagram, various % combination of Labrafac Lipophile WL 1349, Solutol HS 15, Transcutol HP and distilled water were selected. Formulations which passed physical stability studies were selected for further studies such as globule size, zeta potential, in vitro release, ex vivo permeation, in vitro lipolysis studies, bioavailability studies and cytotoxicity against glioblastoma cells (U-87). The optimized NC (NE-SB1) had small average globule diameter of 67 ± 6 nm with zeta potential of -37 ± 2.5 mv which indicated long-term dispersion stability. During in vitro lipolysis study, the digestion rate of medium chain triglycerides increased with decreased globule diameter. Statistically significant difference was found in AUC0-inf of NC formulation (p < 0.05) compared to CU suspension. The relative bioavailability of NC was found 11.88 ± 0.47 with respect to CU suspension. During cytotoxicity studies, IC50 of CU solution on U87 cells was found 24.23 µM, while for the NE- SB1 it was 16.41 µM. The optimized formulation was found to be stable during 6 months of accelerated stability. The overall results revealed that the CU-loaded NC is a very effective approach for enhancing the oral absorption of poorly water-soluble drug CU and have great potential for future clinical application.

Optimal exploitation of spatially distributed trophic resources and population stability

USGS Publications Warehouse

Basset, A.; Fedele, M.; DeAngelis, D.L.

2002-01-01

The relationships between optimal foraging of individuals and population stability are addressed by testing, with a spatially explicit model, the effect of patch departure behaviour on individual energetics and population stability. A factorial experimental design was used to analyse the relevance of the behavioural factor in relation to three factors that are known to affect individual energetics; i.e. resource growth rate (RGR), assimilation efficiency (AE), and body size of individuals. The factorial combination of these factors produced 432 cases, and 1000 replicate simulations were run for each case. Net energy intake rates of the modelled consumers increased with increasing RGR, consumer AE, and consumer body size, as expected. Moreover, through their patch departure behaviour, by selecting the resource level at which they departed from the patch, individuals managed to substantially increase their net energy intake rates. Population stability was also affected by the behavioural factors and by the other factors, but with highly non-linear responses. Whenever resources were limiting for the consumers because of low RGR, large individual body size or low AE, population density at the equilibrium was directly related to the patch departure behaviour; on the other hand, optimal patch departure behaviour, which maximised the net energy intake at the individual level, had a negative influence on population stability whenever resource availability was high for the consumers. The consumer growth rate (r) and numerical dynamics, as well as the spatial and temporal fluctuations of resource density, which were the proximate causes of population stability or instability, were affected by the behavioural factor as strongly or even more strongly than by the others factors considered here. Therefore, patch departure behaviour can act as a feedback control of individual energetics, allowing consumers to optimise a potential trade-off between short-term individual fitness and long-term population stability. ?? 2002 Elsevier Science B.V. All rights reserved.

CEMENTITIOUS GROUT FOR CLOSING SRS HIGH LEVEL WASTE TANKS - #12315

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

Langton, C.; Burns, H.; Stefanko, D.

2012-01-10

In 1997, the first two United States Department of Energy (US DOE) high level waste tanks (Tanks 17-F and 20-F: Type IV, single shell tanks) were taken out of service (permanently closed) at the Savannah River Site (SRS). In 2012, the DOE plans to remove from service two additional Savannah River Site (SRS) Type IV high-level waste tanks, Tanks 18-F and 19-F. These tanks were constructed in the late 1950's and received low-heat waste and do not contain cooling coils. Operational closure of Tanks 18-F and 19-F is intended to be consistent with the applicable requirements of the Resource Conservationmore » and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and will be performed in accordance with South Carolina Department of Health and Environmental Control (SCDHEC). The closure will physically stabilize two 4.92E+04 cubic meter (1.3 E+06 gallon) carbon steel tanks and isolate and stabilize any residual contaminants left in the tanks. The closure will also fill, physically stabilize and isolate ancillary equipment abandoned in the tanks. A Performance Assessment (PA) has been developed to assess the long-term fate and transport of residual contamination in the environment resulting from the operational closure of the F-Area Tank Farm (FTF) waste tanks. Next generation flowable, zero-bleed cementitious grouts were designed, tested, and specified for closing Tanks 18-F and 19-F and for filling the abandoned equipment. Fill requirements were developed for both the tank and equipment grouts. All grout formulations were required to be alkaline with a pH of 12.4 and chemically reduction potential (Eh) of -200 to -400 to stabilize selected potential contaminants of concern. This was achieved by including Portland cement and Grade 100 slag in the mixes, respectively. Ingredients and proportions of cementitious reagents were selected and adjusted, respectively, to support the mass placement strategy developed by closure operations. Subsequent down selection was based on compressive strength and saturated hydraulic conductivity results. Fresh slurry property results were used as the first level of screening. A high range water reducing admixture and a viscosity modifying admixture were used to adjust slurry properties to achieve flowable grouts. Adiabatic calorimeter results were used as the second level screening. The third level of screening was used to design mixes that were consistent with the fill material parameters used in the F-Tank Farm Performance Assessment which was developed to assess the long-term fate and transport of residual contamination in the environment resulting from the operational closures.« less

A Long-Term Outcome Study of Selective Mutism in Childhood

ERIC Educational Resources Information Center

Steinhausen, Hans-Christoph; Wachter, Miriam; Laimbock, Karin; Metzke, Christa Winkler

2006-01-01

Objective: Controlled study of the long-term outcome of selective mutism (SM) in childhood. Method: A sample of 33 young adults with SM in childhood and two age- and gender-matched comparison groups were studied. The latter comprised 26 young adults with anxiety disorders in childhood (ANX) and 30 young adults with no psychiatric disorders during…

Long-term assessment of financial maturity, diameter-limit selection in the central Appalachians

Treesearch

Thomas M. Schuler; David W. McGill

2007-01-01

Financial maturity, diameter-limit (FMDL) selection was proposed more than three decades ago as a replacement for diameter-limit cutting. FMDL incorporates financial maturity guidelines for individual trees, high-priority removal of poorquality trees, and guidelines for residual basal area. We provide the first long-term assessment of this practice after more than...

[Attention therapy for children - long-term affects of the ATTENTIONER].

PubMed

Jacobs, Claus; Petermann, Franz

2008-11-01

A high percentage of children are affected by attention deficit disorders. For a large proportion the cardinal symptom is inattention; in particular, deficits in selective attention prevail. The ATTENTIONER offers an effective training method for the treatment of selective attention deficit. In 2007, long-term effects of therapy were already reported by Jacobs and Petermann, who examined children ten weeks after therapy on average. In the current study three measurements were conducted: pre-intervention, post-intervention, and at follow-up ten to 76 months after post-intervention. Significant long-term effects on measures of selective attention were observed. At follow-up the majority of patients achieved average results which were not clinically relevant. For most children stable therapy effects can be achieved with the ATTENTIONER.

Long-term biological hydrogen production by agar immobilized Rhodobacter capsulatus in a sequential batch photobioreactor.

PubMed

Elkahlout, Kamal; Alipour, Siamak; Eroglu, Inci; Gunduz, Ufuk; Yucel, Meral

2017-04-01

In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best results with both bacterial strains immobilized in 4% (w/v) agar. Cell concentration was increased from 2.5 to 5 mg dcw mL -1 agar and it was found that increasing cell concentration of wild-type strain caused decrease in yield and productivity while these parameters improved by increasing cell concentration of mutant strain. Also, the hydrogen production time has extended from 17 days up to 60 days according to the process conditions and parameters. Hydrogen production by immobilized photosynthetic bacteria is a convenient technology for hydrogen production as it enables to produce hydrogen with high organic acid concentrations comparing to suspended cultures. Besides, immobilization increases the stability of the system and allowed sequential batch operation for long-term application.

Nanoparticles in Medicine: Selected Observations and Experimental Caveats

PubMed Central

Thomsen, Sharon; Pearce, John A.; Giustini, Andrew; Hoopes, P. Jack

2014-01-01

Medically useful nanoparticles measure 1-100 nm in at least one dimension and are engineered and manufactured for specific diagnostic and treatment applications. Most nanoparticles used currently used in medicine are engineered and manufactured for specific purposes. Medically significant nanoparticles are composed of a 1) central core that is usually the medically active component, 2) one or more layers of organic or inorganic materials that forms a capsule (corona) covering the core and 3) an outer surface layer that interacts with the environment and/or targeted cells and tissues. Effective nanoparticle function in the living, intact animal or human requires electrochemical stability necessary to bypass the reticuloendothelial system (RES) and avoid filtration through the renal glomerulus into the urine. Nanoparticles are present in “natural” as well as the manufacturing and clinical environments thus could pose as significant toxins because of their small sizes, their chemical and drug content and potential effect of causing long term disease including allergies, chronic inflammation and cancer. Currently published studies have focused on the effects of nanoparticles on cells in the extremely artificial environments of cell cultures. More clinical and preclinical studies documenting the short term and long term effects nanoparticle in the intact experimental animal and human are needed. PMID:25301992

Strategies for Stabilizing Nitrogenous Compounds in ECLSS Wastewater: Top-Down System Design and Unit Operation Selection with Focus on Bio-Regenerative Processes for Short and Long Term Scenarios

NASA Technical Reports Server (NTRS)

Lunn, Griffin M.

2011-01-01

Water recycling and eventual nutrient recovery is crucial for surviving in or past low earth orbit. New approaches and syste.m architecture considerations need to be addressed to meet current and future system requirements. This paper proposes a flexible system architecture that breaks down pretreatment , steps into discrete areas where multiple unit operations can be considered. An overview focusing on the urea and ammonia conversion steps allows an analysis on each process's strengths and weaknesses and synergy with upstream and downstream processing. Process technologies to be covered include chemical pretreatment, biological urea hydrolysis, chemical urea hydrolysis, combined nitrification-denitrification, nitrate nitrification, anammox denitrification, and regenerative ammonia absorption through struvite formation. Biological processes are considered mainly for their ability to both maximize water recovery and to produce nutrients for future plant systems. Unit operations can be considered for traditional equivalent system mass requirements in the near term or what they can provide downstream in the form of usable chemicals or nutrients for the long term closed-loop ecological control and life support system. Optimally this would allow a system to meet the former but to support the latter without major modification.

Long-term (in)stability of the climate-streamflow relationship

NASA Astrophysics Data System (ADS)

Saft, Margarita; Peel, Murray; Coxon, Gemma; Freer, Jim; Parajka, Juraj; Woods, Ross

2017-04-01

Land use changes have long been known to alter streamflow production for a given climatic input. Recently, extended shifts in climate were also shown to be capable of altering catchment internal functioning and streamflow production for a given climatic input. This study investigates the stability of climate-streamflow relationships in natural catchments in different regions of the world for the first time, using datasets of natural/reference catchments from Europe, US, and Australia. Changes in climate-streamflow relationships are investigated statistically on the interannual to interdecadal timescale and related to interdecadal climate variability. We compare the frequency and magnitude of shifts in climate-streamflow relationship between different regions, and discuss what any differences in shift frequency and magnitude might be related to. This study draws attention to the issues of catchment vulnerability to changes in external factors, catchment-climate co-evolution, and long-term catchment memory.

Measuring Stability and Security in Iraq: Report to Congress in Accordance with the Department of Defense Appropriations Act 2007 (Section 9010, Public Law 109-289)

DTIC Science & Technology

2006-11-01

initiatives. Political Stability Iraq’s Council of Representatives has passed key legislation to initiate the constitutional review process, to...facilitate foreign invest- ment, and to outline a process for region formation. Most important for long-term political stability is the success of...November 30, 2006 5 1. Stability and Security in Iraq 1.1 Political Stability 1.1.1 Steps to a Free and Self-Governing Iraq As detailed in the August

A discussion for stabilization time of carbon steel in atmospheric corrosion

NASA Astrophysics Data System (ADS)

Zhang, Zong-kai; Ma, Xiao-bing; Cai, Yi-kun

2017-09-01

Stabilization time is an important parameter in long-term prediction of carbon steel corrosion in atmosphere. The range of the stabilization time of carbon steel in atmospheric corrosion has been published in many scientific literatures. However, the results may not precise because engineering experiences is dominant. This paper deals with the recalculation of stabilization time based on ISO CORRAG program, and analyzes the results and makes a comparison to the data mentioned above. In addition, a new thinking to obtain stabilization time will be proposed.

The DOD Role in African Policy

DTIC Science & Technology

1993-01-01

best hope for Africa’s long-term political stability . If democracy is indeed the political system best suited to cultural diversity, then it should...flourish in Africa. The United States should therefore strengthen programs, such as security assistance, that can enhance political stability while...involvement would seem to be a natural way to encourage democracy and political stability in Africa. To do so, however, DOD needs to maintain its

Effects of freeze-thaw on characteristics of new KMP binder stabilized Zn- and Pb-contaminated soils.

PubMed

Wei, Ming-Li; Du, Yan-Jun; Reddy, Krishna R; Wu, Hao-Liang

2015-12-01

For viable and sustainable reuse of solidified/stabilized heavy metal-contaminated soils as roadway subgrade materials, long-term durability of these soils should be ensured. A new binder, KMP, has been developed for solidifying/stabilizing soils contaminated with high concentrations of heavy metals. However, the effects of long-term extreme weather conditions including freeze and thaw on the leachability and strength of the KMP stabilized contaminated soils have not been investigated. This study presents a systematic investigation on the impacts of freeze-thaw cycle on leachability, strength, and microstructural characteristics of the KMP stabilized soils spiked with Zn and Pb individually and together. For comparison purpose, Portland cement is also tested as a conventional binder. Several series of tests are conducted including the toxicity characteristic leaching procedure (TCLP), modified European Community Bureau of Reference (BCR) sequential extraction procedure, unconfined compression test (UCT), and mercury intrusion porosimetry (MIP). The results demonstrate that the freeze-thaw cycles have much less impact on the leachability and strength of the KMP stabilized soils as compared to the PC stabilized soils. After the freeze-thaw cycle tests, the KMP stabilized soils display much lower leachability, mass loss, and strength loss. These results are assessed based on the chemical speciation of Zn and Pb, and pore size distribution of the soils. Overall, this study demonstrates that the KMP stabilized heavy metal-contaminated soils perform well under the freeze-thaw conditions.

Examining the Long-Term Stability of Overgeneral Autobiographical Memory

PubMed Central

Sumner, Jennifer A.; Mineka, Susan; Zinbarg, Richard E.; Craske, Michelle G.; Vrshek-Schallhorn, Suzanne; Epstein, Alyssa

2013-01-01

Overgeneral autobiographical memory (OGM) is a proposed trait-marker for vulnerability to depression, but relatively little work has examined its long-term stability. This study investigated the stability of OGM over several years in 271 late adolescents and young adults participating in a larger longitudinal study of risk for emotional disorders. The Autobiographical Memory Test (AMT) was administered twice, with test-retest intervals ranging from approximately 3 to 6 years. There was evidence of significant but modest stability in OGM over several years. Specifically, Spearman rank correlations (ρs) between the proportions of specific and categoric memories generated on the two AMTs were .31 and .32, respectively. We did not find evidence that the stability of OGM was moderated by the length of the test-retest interval. Furthermore, the stability coefficients for OGM for individuals with and without a lifetime history of major depressive disorder (MDD) were relatively similar in magnitude and not significantly different from one another (ρs = .34 and .42 for the proportions of specific and categoric memories for those with a history of MDD; ρs = .31 for both the proportions of specific and categoric memories for those without a history of MDD). Implications for the conceptualization of OGM are discussed. PMID:23439226

Pressure measurements with a precision of 0.001 ppm in magnetic fields at low temperatures

NASA Astrophysics Data System (ADS)

Miura, Y.; Matsushima, N.; Ando, T.; Kuno, S.; Inoue, S.; Ito, K.; Mamiya, T.

1993-11-01

Pressure measurements made by an ac bridge technique with a precision of 0.001 ppm in magnetic fields at low temperatures using a Straty-Adams type gauge are described. In order to improve the sensitivity and the long-term stability of the bridge system, coaxial cables without dielectric insulator were developed, with a small cable capacitance temperature coefficient of the impedance. This pressure measurement system has a sensitivity of dP/P˜5×10-10 and a long-term stability of dP/P˜2.4×10-9 over 18 h. This is especially useful for measurements such as electric and magnetic susceptibility measurements in magnetic fields at low temperatures requiring a high precision.

All fiber-coupled, long-term stable timing distribution for free-electron lasers with few-femtosecond jitter

PubMed Central

Şafak, K.; Xin, M.; Callahan, P. T.; Peng, M. Y.; Kärtner, F. X.

2015-01-01

We report recent progress made in a complete fiber-optic, high-precision, long-term stable timing distribution system for synchronization of next generation X-ray free-electron lasers. Timing jitter characterization of the master laser shows less than 170-as RMS integrated jitter for frequencies above 10 kHz, limited by the detection noise floor. Timing stabilization of a 3.5-km polarization-maintaining fiber link is successfully achieved with an RMS drift of 3.3 fs over 200 h of operation using all fiber-coupled elements. This all fiber-optic implementation will greatly reduce the complexity of optical alignment in timing distribution systems and improve the overall mechanical and timing stability of the system. PMID:26798814

Novel functional Renilla luciferase mutant provides long-term serum stability and high luminescence activity.

PubMed

Song, Woo Chul; Sung, Hye-Jin; Park, Kyung Soo; Choi, Jeong-Woo; Cho, Je-Yeol; Um, Soong Ho

2013-10-01

Fluorescent and luminescent chemical probes are essential in recent medical diagnostics. However, the use of these probes in vivo has raised concerns due to their low sensitivity, background signal interference, and non-biocompatibility. Therefore, biological chromophores have received much attention as new alternatives. In particular, luciferase, a class of oxidative enzyme with bioluminescence, has emerged as a promising fluorophore due to its improved biocompatibility. However, the enzyme usually possesses weaker luminescence and stability relative to its chemically-based competitors. Here, we report a novel functional mutant luciferase with both enhanced luminescence and long-term serum stability. For the preparation of the modified Renilla luciferase, a new bacterial subcloning design was established. The luciferase coding DNA sequence was redesigned so that mutant luciferase could be easily expressed in an Escherichia coli system. The mutant Renilla luciferase, which we called "m-Rluc," demonstrated characteristic enzymatic functions and showed a 5.6-fold increase in luminescence activity. In addition, the enzyme's physiological stability remained >80% for more than 5days, in contrast to conventional luciferase, termed "hrluc," which disappeared within a few hours. We suggest that this novel biological luciferase probe may be a great tool for both in vitro and in vivo medical diagnostics. Copyright © 2013 Elsevier Inc. All rights reserved.

Trans-sinusal maxillary distraction for correction of midfacial hypoplasia: long-term clinical results.

PubMed

Nadjmi, N; Schutyser, F; Van Erum, R

2006-10-01

Maxillary distraction osteogenesis is indicated in severe angle class III malocclusions, and severe maxillary hypoplasia among some cleft patients and other craniofacial deformities. Twenty patients, aged 8-48 years (mean 17.8+/-10.5 SD) with maxillary and midfacial hypoplasia were treated. The follow-up period was 13-65 months (mean 35+/-16.3 SD). A trans-sinusal maxillary distractor was placed intraorally at each side of the maxilla. The distraction vector was predicted using specialist software, and was transferred to the patients using stereolithographic models and individual templates. A (high) Le Fort I type osteotomy was performed. The amount of activation varied from 8 to 17.5 mm (mean 13.1+/-2.9 SD). Soft and hard tissue formation resulted in complete healing across the distraction gaps. The distractors are almost completely submerged, and can be left in place as long as necessary to avoid relapse. Wit's appraisal was used to measure the stability of the long-term distraction results. Results up to 5 years after distraction showed considerable maxillary advancement with long-term stability. Ongoing growth of the facial skeleton must be considered when distraction osteogenesis is chosen in growing patients.

Maternal Mental Illness and the Safety and Stability of Maltreated Children

ERIC Educational Resources Information Center

Kohl, Patricia L.; Jonson-Reid, Melissa; Drake, Brett

2011-01-01

Objective: Children of mothers with mental illness are at risk for multiple untoward outcomes, including child maltreatment and foster care placement. The purpose of this analysis was to determine the association between maternal mental illness and children's long term safety and stability. Methods: A multi-sector administrative dataset from the…

Long-term effects of seeding after wildfire on vegetation in Great Basin shrubland ecosystems

Treesearch

Kevin C. Knutson; David A. Pyke; Troy A. Wirth; Robert S. Arkle; David S. Pilliod; Matthew L. Brooks; Jeanne C. Chambers; James B. Grace

2014-01-01

Invasive annual grasses alter fire regimes in shrubland ecosystems of the western USA, threatening ecosystem function and fragmenting habitats necessary for shrub-obligate species such as greater sage-grouse. Post-fire stabilization and rehabilitation treatments have been administered to stabilize soils, reduce invasive species spread and restore or establish...

Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil

USDA-ARS?s Scientific Manuscript database

Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar’s sorptive property and recalcitrance in soil. To understand the role of carboxyl functional groups on heavy metal stabilization, cottonseed hull biochar and flax shive steam activated biochar having low O/C ratio...

Long-Term Stability of Screening for Behavioral and Emotional Risk

ERIC Educational Resources Information Center

Dowdy, Erin; Nylund-Gibson, Karen; Felix, Erika D.; Morovati, Diane; Carnazzo, Katherine W.; Dever, Bridget V.

2014-01-01

The practice of screening students to identify behavioral and emotional risk is gaining momentum, with limited guidance regarding the frequency with which screenings should occur. Screening frequency decisions are influenced by the stability of the constructs assessed and changes in risk status over time. This study investigated the 4-year…

30 CFR 819.19 - Auger mining: Backfilling and grading.

Code of Federal Regulations, 2010 CFR

2010-07-01

... safety factor for the stability of the backfill of at least 1.3. (2) All spoil generated by the auger... nonacid-, nontoxic-forming material and the backfill graded to a slope which is compatible with the approved postmining land use and which provides adequate drainage and long-term stability. (4) Any remnant...

Process and formulation effects on solar thermal drum dried prune pomace

USDA-ARS?s Scientific Manuscript database

The processing of dried plums into prune juice and concentrate yields prune pomace as a coproduct; the pomace could potentially be utilized as a food ingredient but requires stabilization for long-term storage. Drum drying is one method that could be used to dry and stabilize prune pomace, and a dru...

Impact of pilling and long-term topsoil storage on the potential soil microbial activity in the Northern Chihuahuan Desert

USDA-ARS?s Scientific Manuscript database

Cryptobiotic soil crusts in arid regions contribute to ecosystem stability through increased water infiltration, soil aggregate stability, and nutrient cycling between the soil community and vascular plants. Natural gas mining involves removal of the topsoil, including surface crust, and storage of ...

Factors Associated with Caregiver Stability in Permanent Placements: A Classification Tree Approach

ERIC Educational Resources Information Center

Proctor, Laura J.; Van Dusen Randazzo, Katherine; Litrownik, Alan J.; Newton, Rae R.; Davis, Inger P.; Villodas, Miguel

2011-01-01

Objective: Identify individual and environmental variables associated with caregiver stability and instability for children in diverse permanent placement types (i.e., reunification, adoption, and long-term foster care/guardianship with relatives or non-relatives), following 5 or more months in out-of-home care prior to age 4 due to substantiated…

Contribution of plant lignin to the soil organic matter formation and stabilization

USDA-ARS?s Scientific Manuscript database

Lignin is the third most abundant plant constituent after cellulose and hemicellulose and thought to be one of the building blocks for soil organic matter formation. Lignin can be used as a predictor for long-term soil organic matter stabilization and C sequestration. Soils and humic acids from fo...

Long-term efficiency of soil stabilization with apatite and Slovakite: the impact of two earthworm species (Lumbricus terrestris and Dendrobaena veneta) on lead bioaccessibility and soil functioning.

PubMed

Tica, D; Udovic, M; Lestan, D

2013-03-01

Remediation soil is exposed to various environmental factors over time that can affect the final success of the operation. In the present study, we assessed Pb bioaccessibility and microbial activity in industrially polluted soil (Arnoldstein, Austria) stabilized with 5% (w/w) of Slovakite and 5% (w/w) of apatite soil after exposure to two earthworm species, Lumbricus terrestris and Dendrobaena veneta, used as model environmental biotic soil factors. Stabilization resulted in reduced Pb bioaccessibility, as assessed with one-step extraction tests and six-step sequential extraction, and improved soil functioning, mirrored in reduced β-glucosidase activity in soil. Both earthworm species increased Pb bioaccessibility, thus decreasing the initial stabilization efficacy and indicating the importance of considering the long-term fate of remediated soil. The earthworm species had different effects on soil enzyme activity, which can be attributed to species-specific microbial populations in earthworm gut acting on the ingested soil. Copyright © 2012 Elsevier Ltd. All rights reserved.

Perovskite Solar Cells with Inorganic Electron- and Hole-Transport Layers Exhibiting Long-Term (≈500 h) Stability at 85 °C under Continuous 1 Sun Illumination in Ambient Air.

PubMed

Seo, Seongrok; Jeong, Seonghwa; Bae, Changdeuck; Park, Nam-Gyu; Shin, Hyunjung

2018-05-22

Despite the high power conversion efficiency (PCE) of perovskite solar cells (PSCs), poor long-term stability is one of the main obstacles preventing their commercialization. Several approaches to enhance the stability of PSCs have been proposed. However, an accelerating stability test of PSCs at high temperature under the operating conditions in ambient air remains still to be demonstrated. Herein, interface-engineered stable PSCs with inorganic charge-transport layers are shown. The highly conductive Al-doped ZnO films act as efficient electron-transporting layers as well as dense passivation layers. This layer prevents underneath perovskite from moisture contact, evaporation of components, and reaction with a metal electrode. Finally, inverted-type PSCs with inorganic charge-transport layers exhibit a PCE of 18.45% and retain 86.7% of the initial efficiency for 500 h under continuous 1 Sun illumination at 85 °C in ambient air with electrical biases (at maximum power point tracking). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Long-term neurodevelopmental outcome after selective feticide in monochorionic pregnancies.

PubMed

van Klink, Jmm; Koopman, H M; Middeldorp, J M; Klumper, F J; Rijken, M; Oepkes, D; Lopriore, E

2015-10-01

To assess the incidence of and risk factors for adverse long-term neurodevelopmental outcome in complicated monochorionic pregnancies treated with selective feticide at our centre between 2000 and 2011. Observational cohort study. National referral centre for fetal therapy (Leiden University Medical Centre, the Netherlands). Neurodevelopmental outcome was assessed in 74 long-term survivors. Children, at least 2 years of age, underwent an assessment of neurologic, motor and cognitive development using standardised psychometric tests and the parents completed a behavioural questionnaire. A composite outcome termed neurodevelopmental impairment including cerebral palsy (GMFCS II-V), cognitive and/or motor test score of <70, bilateral blindness or bilateral deafness requiring amplification. A total of 131 monochorionic pregnancies were treated with selective feticide at the Leiden University Medical Centre. Overall survival rate was 88/131 (67%). Long-term outcome was assessed in 74/88 (84%). Neurodevelopmental impairment was detected in 5/74 [6.8%, 95% confidence interval (CI), 1.1-12.5] of survivors. Overall adverse outcome, including perinatal mortality or neurodevelopmental impairment was 48/131 (36.6%). In multivariate analysis, parental educational level was associated with cognitive test scores (regression coefficient B 3.9, 95% CI 1.8-6.0). Behavioural problems were reported in 10/69 (14.5%). Adverse long-term outcome in survivor twins of complicated monochorionic pregnancies treated with selective feticide appears to be more prevalent than in the general population. Cognitive test scores were associated with parental educational level. Neurodevelopmental impairment after selective feticide was detected in 5/74 (6.8%, 95% CI 1.1-12.5) of survivors. © 2015 Royal College of Obstetricians and Gynaecologists.

Chest wall stabilization and reconstruction: short and long-term results 5 years after the introduction of a new titanium plates system.

PubMed

De Palma, Angela; Sollitto, Francesco; Loizzi, Domenico; Di Gennaro, Francesco; Scarascia, Daniele; Carlucci, Annalisa; Giudice, Giuseppe; Armenio, Andrea; Ludovico, Rossana; Loizzi, Michele

2016-03-01

We report short and long-term results with the dedicated Synthes(®) titanium plates system, introduced 5 years ago, for chest wall stabilization and reconstruction. We retrospectively analyzed (January 2010 to December 2014) 27 consecutive patients (22 males, 5 females; range 16-83 years, median age 60 years), treated with this system: primary [3] and secondary [8] chest wall tumor; flail chest [5]; multiple ribs fractures [5]; sternal dehiscence-diastasis [3]; sternal fracture [1]; sternoclavicular joint dislocation [1]; Poland syndrome [1]. Short-term results were evaluated as: operating time, post-operative morbidity, mortality, hospital stay; long-term results as: survival, plates-related morbidity, spirometric values, chest pain [measured with Verbal Rating Scale (VRS) and SF12 standard V1 questionnaire]. Each patient received from 1 to 10 (median 2) titanium plates/splints; median operating time was 150 min (range: 115-430 min). Post-operative course: 15 patients (55.6%) uneventful, 10 (37%) minor complications, 2 (7.4%) major complications; no post-operative mortality. Median post-operative hospital stay was 13 days (range: 5-129 days). At a median follow-up of 20 months (range: 1-59 months), 21 patients (78%) were alive, 6 (22%) died. Three patients presented long-term plates-related morbidity: plates rupture [2], pin plate dislodgment [1]; two required a second surgical look. One-year from surgery median spirometric values were: FVC 3.31 L (90%), FEV1 2.46 L (78%), DLCO 20.9 mL/mmHg/min (76%). On 21 alive patients, 7 (33.3%) reported no pain (VRS score 0), 10 (47.6%) mild (score 2), 4 (19.1%) moderate (score 4), no-one severe (score >4); 15 (71.5%) reported none or mild, 6 (28.5%) moderate pain influencing quality of life. An optimal chest wall stabilization and reconstruction was achieved with the Synthes(®) titanium plates system, with minimal morbidity, no post-operative mortality, acceptable operating time and post-operative hospital stay. Long-term restoration of a normal respiratory function was achieved, with minimal plates-related morbidity and chest pain.

CO2 laser oscillators for laser radar applications

NASA Technical Reports Server (NTRS)

Freed, C.

1990-01-01

This paper reviews the spectral purity, frequency stability, and long-term stabilization of newly developed CO2 isotope lasers. Extremely high spectral purity, and short-term stability of less than 1.5 x 10 to the -13th have been achieved. A brief description on using CO2 isotope lasers as secondary frequency standards and in optical radar is given. The design and output characteristics of a single frequency, TEM00q mode, variable pulse width, hybrid TE CO2 laser system is also described. The frequency chirp in the output has been measured and almost completely eliminated by means of a novel technique.

Long-term risk analysis associated with nuclear waste disposal in space

NASA Technical Reports Server (NTRS)

Friedlander, A. L.; Davis, D. R.

1979-01-01

An assessment and verification of previous analytic results on the long term risk of earth reentry for hazardous payloads is presented. The two areas were studied: (1) stability of nominal, near-circular storage orbits in the regions between Venus and earth and between earth and Mars, and (2) probability of earth reentry for off-nominal planet-crossing orbits resulting from deployment system failures. In the first area, numerical integrations of the equations of motion are compared with stability predications based on secular perturbation theory. The agreement is good in terms of the heliocentric distances covered and the general behavior of the orbital history, although certain near-resonance situations can lead to difficulty. In the second area, a Monte Carlo simulation of orbital evolution is used and the results compared with Opik's analytic theory of planetary encounters and collision statistics, with data verified to within a close order-of-magnitude.

Synaptic Scaling Enables Dynamically Distinct Short- and Long-Term Memory Formation

PubMed Central

Tetzlaff, Christian; Kolodziejski, Christoph; Timme, Marc; Tsodyks, Misha; Wörgötter, Florentin

2013-01-01

Memory storage in the brain relies on mechanisms acting on time scales from minutes, for long-term synaptic potentiation, to days, for memory consolidation. During such processes, neural circuits distinguish synapses relevant for forming a long-term storage, which are consolidated, from synapses of short-term storage, which fade. How time scale integration and synaptic differentiation is simultaneously achieved remains unclear. Here we show that synaptic scaling – a slow process usually associated with the maintenance of activity homeostasis – combined with synaptic plasticity may simultaneously achieve both, thereby providing a natural separation of short- from long-term storage. The interaction between plasticity and scaling provides also an explanation for an established paradox where memory consolidation critically depends on the exact order of learning and recall. These results indicate that scaling may be fundamental for stabilizing memories, providing a dynamic link between early and late memory formation processes. PMID:24204240

Synaptic scaling enables dynamically distinct short- and long-term memory formation.

PubMed

Tetzlaff, Christian; Kolodziejski, Christoph; Timme, Marc; Tsodyks, Misha; Wörgötter, Florentin

2013-10-01

Memory storage in the brain relies on mechanisms acting on time scales from minutes, for long-term synaptic potentiation, to days, for memory consolidation. During such processes, neural circuits distinguish synapses relevant for forming a long-term storage, which are consolidated, from synapses of short-term storage, which fade. How time scale integration and synaptic differentiation is simultaneously achieved remains unclear. Here we show that synaptic scaling - a slow process usually associated with the maintenance of activity homeostasis - combined with synaptic plasticity may simultaneously achieve both, thereby providing a natural separation of short- from long-term storage. The interaction between plasticity and scaling provides also an explanation for an established paradox where memory consolidation critically depends on the exact order of learning and recall. These results indicate that scaling may be fundamental for stabilizing memories, providing a dynamic link between early and late memory formation processes.

Epicardial clip occlusion of the left atrial appendage during cardiac surgery provides optimal surgical results and long-term stability.

PubMed

Kurfirst, Vojtech; Mokrácek, Aleš; Canádyová, Júlia; Frána, Radim; Zeman, Petr

2017-07-01

Occlusion of the left atrial appendage (LAA) has become an integral and important part of the surgical treatment of atrial fibrillation. Different methods of surgical occlusion of the LAA have been associated with varying levels of short- and long-term success for closure. The purpose of this study was to evaluate long-term results of epicardial placement and endocardial occlusion in patients undergoing cardiac operative procedures. A total of 101 patients (average age 65.7 years) undergoing cardiac operative procedures with the epicardial AtriClip Exclusion System of the LAA were enrolled in the study. The AtriClip was placed via a sternotomy or a thoracotomy or from a thoracoscopic approach. Postoperative variables, such as thromboembolic events, clip stability and endocardial leakage around the device, were examined by transoesophageal echocardiography (TEE) and/or computed tomography. Perioperative clip implantation was achieved in 98% of patients. TEE and/or computed tomography conducted during the follow-up period, comprising 1873 patient-months with a mean duration of 18 ± 11 months, revealed no clip migration, no leakage around the device and no clot formation near the remnant cul-de-sac. During the follow-up period, 4 of the cardiac patients experienced transitory ischaemic attacks, whereas no patient experienced a cerebrovascular attack. The Epicardial AtriClip Exclusion System of the LAA appears to be a feasable and safe operative method with a high success rate. Long-term follow-up confirmed clip stability, complete occlussion of the LAA and absence of any atrial fibrilation-related thromboembolic events. These results need to be confirmed by a larger, multicentre study. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Application of Radiation Chemistry to Some Selected Technological Issues Related to the Development of Nuclear Energy.

PubMed

Bobrowski, Krzysztof; Skotnicki, Konrad; Szreder, Tomasz

2016-10-01

The most important contributions of radiation chemistry to some selected technological issues related to water-cooled reactors, reprocessing of spent nuclear fuel and high-level radioactive wastes, and fuel evolution during final radioactive waste disposal are highlighted. Chemical reactions occurring at the operating temperatures and pressures of reactors and involving primary transients and stable products from water radiolysis are presented and discussed in terms of the kinetic parameters and radiation chemical yields. The knowledge of these parameters is essential since they serve as input data to the models of water radiolysis in the primary loop of light water reactors and super critical water reactors. Selected features of water radiolysis in heterogeneous systems, such as aqueous nanoparticle suspensions and slurries, ceramic oxides surfaces, nanoporous, and cement-based materials, are discussed. They are of particular concern in the primary cooling loops in nuclear reactors and long-term storage of nuclear waste in geological repositories. This also includes radiation-induced processes related to corrosion of cladding materials and copper-coated iron canisters, dissolution of spent nuclear fuel, and changes of bentonite clays properties. Radiation-induced processes affecting stability of solvents and solvent extraction ligands as well oxidation states of actinide metal ions during recycling of the spent nuclear fuel are also briefly summarized.

Postsurgical Orthodontic Treatment Planning: a Case Report with 20 Years Follow-up.

PubMed

Farronato, Giampietro; Garagiola, Umberto; Carletti, Vera; Cressoni, Paolo; Mortellaro, Carmen

2011-01-01

Traditionally, maxillofacial deformities are corrected surgically after an initial orthodontic treatment phase. However in, this article, the authors emphasize the postsurgical therapeutic protocol which is extremely important for determining the final and permanent retention of the corrected occlusion. A 55 year old female with severe skeletal Class II malocclusion is presented. Combined surgical and orthodontic correction of the malocclusion was used. : The step-by-step procedure the authors followed for the postsurgical therapy is described. The goals of the postoperative therapy were to restore and rehabilitate neuromuscular function, obtain occlusal stabilization, grind teeth selectively, and final occlusion retention. The importance of a surgical occlusal splint for rehabilitating stomatognathic neuromuscular function postoperatively was demonstrated. Furthermore, the orthodontic-prosthodontic treatment ensured occlusion stability after the surgical correction. The long-term results confirmed the efficacy of the treatment protocol presented here from both functional and aesthetical perspectives. Postsurgical orthodontic treatment is an important step in the surgical and orthodontic therapy of maxillofacial deformities.

Preparation of Ru-doped SnO2-supported Pt catalysts and their electrocatalytic properties for methanol oxidation.

PubMed

Pang, H L; Zhang, X H; Zhong, X X; Liu, B; Wei, X G; Kuang, Y F; Chen, J H

2008-03-01

Ru-doped SnO2 nanoparticles were prepared by chemical precipitation and calcinations at 823 K. Due to high stability in diluted acidic solution, Ru-doped SnO2 nanoparticles were selected as the catalyst support and second catalyst for methanol electrooxidation. The micrograph, elemental composition, and structure of the Ru-doped SnO2 nanoparticles were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, respectively. The electrocatalytic properties of the Ru-doped SnO2-supported Pt catalyst (Pt/Ru-doped SnO2) for methanol oxidation have been investigated by cyclic voltammetry. Under the same loading mass of Pt, the Pt/Ru-doped SnO2 catalyst shows better electrocatalytic performance than the Pt/SnO2 catalyst and the best atomic ratio of Ru to Sn in Ru-doped SnO2 is 1/75. Additionally, the Pt/Ru-doped SnO2 catalyst possesses good long-term cycle stability.

Nanoporous platinum-cobalt alloy for electrochemical sensing for ethanol, hydrogen peroxide, and glucose.

PubMed

Xu, Caixia; Sun, Fenglei; Gao, Hua; Wang, Jinping

2013-05-30

Nanoporous platinum-cobalt (NP-PtCo) alloy with hierarchical nanostructure is straightforwardly fabricated by dealloying PtCoAl alloy in a mild alkaline solution. Selectively etching Al resulted in a hierarchical three-dimensional network nanostructure with a narrow size distribution at 3 nm. The as-prepared NP-PtCo alloy shows superior performance toward ethanol and hydrogen peroxide (H2O2) with highly sensitive response due to its unique electrocatalytic activity. In addition, NP-PtCo also exhibits excellent amperometric durability and long-term stability for H2O2 as well as a good anti-interference toward ascorbic acid, uric acid, and dopamine. The hierarchical nanoporous architecture in PtCo alloy is also highly active for glucose sensing electrooxidation and sensing in a wide linear range. The NP-PtCo alloy holds great application potential for electrochemical sensing with simple preparation, unique catalytic activity, and high structure stability. Copyright © 2013 Elsevier B.V. All rights reserved.

Morpholine Derivative-Functionalized Carbon Dots-Based Fluorescent Probe for Highly Selective Lysosomal Imaging in Living Cells.

PubMed

Wu, Luling; Li, Xiaolin; Ling, Yifei; Huang, Chusen; Jia, Nengqin

2017-08-30

The development of a suitable fluorescent probe for the specific labeling and imaging of lysosomes through the direct visual fluorescent signal is extremely important for understanding the dysfunction of lysosomes, which might induce various pathologies, including neurodegenerative diseases, cancer, and Alzheimer's disease. Herein, a new carbon dot-based fluorescent probe (CDs-PEI-ML) was designed and synthesized for highly selective imaging of lysosomes in live cells. In this probe, PEI (polyethylenimine) is introduced to improve water solubility and provide abundant amine groups for the as-prepared CDs-PEI, and the morpholine group (ML) serves as a targeting unit for lysosomes. More importantly, passivation with PEI could dramatically increase the fluorescence quantum yield of CDs-PEI-ML as well as their stability in fluorescence emission under different excitation wavelength. Consequently, experimental data demonstrated that the target probe CDs-PEI-ML has low cytotoxicity and excellent photostability. Additionally, further live cell imaging experiment indicated that CDs-PEI-ML is a highly selective fluorescent probe for lysosomes. We speculate the mechanism for selective staining of lysosomes that CDs-PEI-ML was initially taken up by lysosomes through the endocytic pathway and then accumulated in acidic lysosomes. It is notable that there was less diffusion of CDs-PEI-ML into cytoplasm, which could be ascribed to the presence of lysosome target group morpholine on surface of CDs-PEI-ML. The blue emission wavelength combined with the high photo stability and ability of long-lasting cell imaging makes CDs-PEI-ML become an alternative fluorescent probe for multicolor labeling and long-term tracking of lysosomes in live cells and the potential application in super-resolution imaging. To best of our knowledge, there are still limited carbon dots-based fluorescent probes that have been studied for specific lysosomal imaging in live cells. The concept of surface functionality of carbon dots will also pave a new avenue for developing carbon dots-based fluorescent probes for subcellular labeling.

Disposal methods

NASA Technical Reports Server (NTRS)

Friedlander, Alan

1991-01-01

A number of disposal options for space nuclear reactors and the associated risks, mostly in the long term, based on probabilities of Earth reentry are discussed. The results are based on a five year study that was conducted between 1978 and 1983 on the space disposal of high level nuclear waste. The study provided assessment of disposal options, stability of disposal or storage orbits, and assessment of the long term risks of Earth reentry of the nuclear waste.

An Autonomous Indicator-based pH Sensor for Oceanographic Research and Monitoring

DTIC Science & Technology

2010-01-01

E-mail: michael.degrandpre@umontana.edu Co-PI: Jim Beck , MSME Sunburst Sensors, LLC, 1121 E. Broadway, Suite 114, Missoula, MT 59802 Phone...NOPP Award Number: ONR- BAA -07-040 NSF Award Number: OCE-0836807 LONG-TERM GOALS This project, funded under NOPP Topic 3A Sensors for...Spaulding continued work on establishing long- term stability of mCP. Jim Beck coordinated improvements to the design of the software and hardware

Hippocampal Focal Knockout of CBP Affects Specific Histone Modifications, Long-Term Potentiation, and Long-Term Memory

PubMed Central

Barrett, Ruth M; Malvaez, Melissa; Kramar, Eniko; Matheos, Dina P; Arrizon, Abraham; Cabrera, Sara M; Lynch, Gary; Greene, Robert W; Wood, Marcelo A

2011-01-01

To identify the role of the histone acetyltransferase (HAT) CREB-binding protein (CBP) in neurons of the CA1 region of the hippocampus during memory formation, we examine the effects of a focal homozygous knockout of CBP on histone modifications, gene expression, synaptic plasticity, and long-term memory. We show that CBP is critical for the in vivo acetylation of lysines on histones H2B, H3, and H4. CBP's homolog p300 was unable to compensate for the loss of CBP. Neurons lacking CBP maintained phosphorylation of the transcription factor CREB, yet failed to activate CREB:CBP-mediated gene expression. Loss of CBP in dorsal CA1 of the hippocampus resulted in selective impairments to long-term potentiation and long-term memory for contextual fear and object recognition. Together, these results suggest a necessary role for specific chromatin modifications, selectively mediated by CBP in the consolidation of memories. PMID:21508930

Short- and long-term responses to molybdenum-99 shortages in nuclear medicine.

PubMed

Ballinger, J R

2010-11-01

Most nuclear medicine studies use (99)Tc(m), which is the decay product of (99)Mo. The world supply of (99)Mo comes from only five nuclear research reactors and availability has been much reduced in recent times owing to problems at the largest reactors. In the short-term there are limited actions that can be taken owing to capacity issues on alternative imaging modalities. In the long-term, stability of (99)Mo supply will rely on a combination of replacing conventional reactors and developing new technologies.

Short- and long-term responses to molybdenum-99 shortages in nuclear medicine

PubMed Central

Ballinger, J R

2010-01-01

Most nuclear medicine studies use 99Tcm, which is the decay product of 99Mo. The world supply of 99Mo comes from only five nuclear research reactors and availability has been much reduced in recent times owing to problems at the largest reactors. In the short-term there are limited actions that can be taken owing to capacity issues on alternative imaging modalities. In the long-term, stability of 99Mo supply will rely on a combination of replacing conventional reactors and developing new technologies. PMID:20965898

Long-Term Stability of One-Inch Condenser Microphones Calibrated at the National Institute of Standards and Technology

PubMed Central

Wagner, Randall P.; Guthrie, William F.

2015-01-01

The devices calibrated most frequently by the acoustical measurement services at the National Institute of Standards and Technology (NIST) over the 50-year period from 1963 to 20121 were one-inch condenser microphones of three specific standard types: LS1Pn, LS1Po, and WS1P. Due to its long history of providing calibrations of such microphones to customers, NIST is in a unique position to analyze data concerning the long-term stability of these devices. This long history has enabled NIST to acquire and aggregate a substantial amount of repeat calibration data for a large number of microphones that belong to various other standards and calibration laboratories. In addition to determining microphone sensitivities at the time of calibration, it is important to have confidence that the microphones do not typically undergo significant drift as compared to the calibration uncertainty during the periods between calibrations. For each of the three microphone types, an average drift rate and approximate 95 % confidence interval were computed by two different statistical methods, and the results from the two methods were found to differ insignificantly in each case. These results apply to typical microphones of these types that are used in a suitable environment and handled with care. The average drift rate for Type LS1Pn microphones was −0.004 dB/year to 0.003 dB/year. The average drift rate for Type LS1Po microphones was −0.016 dB/year to 0.008 dB/year. The average drift rate for Type WS1P microphones was −0.004 dB/year to 0.018 dB/year. For each of these microphone types, the average drift rate is not significantly different from zero. This result is consistent with the performance expected of condenser microphones designed for use as transfer standards. In addition, the values that bound the confidence intervals are well within the limits specified for long-term stability in international standards. Even though these results show very good long-term stability historically for these microphone types, it is expected that periodic calibrations will always be done to track the calibration history of individual microphones and check for anomalies indicative of shifts in sensitivity. PMID:26958445

Temporal Stability and the Effect of Transgenerational Transfer on Fecal Microbiota Structure in a Long Distance Migratory Bird

PubMed Central

Kreisinger, Jakub; Kropáčková, Lucie; Petrželková, Adéla; Adámková, Marie; Tomášek, Oldřich; Martin, Jean-François; Michálková, Romana; Albrecht, Tomáš

2017-01-01

Animal bodies are inhabited by a taxonomically and functionally diverse community of symbiotic and commensal microorganisms. From an ecological and evolutionary perspective, inter-individual variation in host-associated microbiota contributes to physiological and immune system variation. As such, host-associated microbiota may be considered an integral part of the host’s phenotype, serving as a substrate for natural selection. This assumes that host-associated microbiota exhibits high temporal stability, however, and that its composition is shaped by trans-generational transfer or heritable host-associated microbiota modulators encoded by the host genome. Although this concept is widely accepted, its crucial assumptions have rarely been tested in wild vertebrate populations. We performed 16S rRNA metabarcoding on an extensive set of fecal microbiota (FM) samples from an insectivorous, long-distance migratory bird, the barn swallow (Hirundo rustica). Our data revealed clear differences in FM among juveniles and adults as regards taxonomic and functional composition, diversity and co-occurrence network complexity. Multiple FM samples from the same juvenile or adult collected within single breeding seasons exhibited higher similarity than expected by chance, as did adult FM samples over two consecutive years. Despite low effect sizes for FM stability over time at the community level, we identified an adult FM subset with relative abundances exhibiting significant temporal consistency, possibly inducing long-term effects on the host phenotype. Our data also indicate a slight maternal (but not paternal) effect on FM composition in social offspring, though this is unlikely to persist into adulthood. We discuss our findings in the context of both evolution and ecology of microbiota vs. host interactions and barn swallow biology. PMID:28220109

Modeling the relations between flow regime components, species traits, and spawning success of fishes in warmwater streams

USGS Publications Warehouse

Craven, S.W.; Peterson, J.T.; Freeman, Mary C.; Kwak, T.J.; Irwin, E.

2010-01-01

Modifications to stream hydrologic regimes can have a profound influence on the dynamics of their fish populations. Using hierarchical linear models, we examined the relations between flow regime and young-of-year fish density using fish sampling and discharge data from three different warmwater streams in Illinois, Alabama, and Georgia. We used an information theoretic approach to evaluate the relative support for models describing hypothesized influences of five flow regime components representing: short-term high and low flows; short-term flow stability; and long-term mean flows and flow stability on fish reproductive success during fish spawning and rearing periods. We also evaluated the influence of ten fish species traits on fish reproductive success. Species traits included spawning duration, reproductive strategy, egg incubation rate, swimming locomotion morphology, general habitat preference, and food habits. Model selection results indicated that young-of-year fish density was positively related to short-term high flows during the spawning period and negatively related to flow variability during the rearing period. However, the effect of the flow regime components varied substantially among species, but was related to species traits. The effect of short-term high flows on the reproductive success was lower for species that broadcast their eggs during spawning. Species with cruiser swimming locomotion morphologies (e.g., Micropterus) also were more vulnerable to variable flows during the rearing period. Our models provide insight into the conditions and timing of flows that influence the reproductive success of warmwater stream fishes and may guide decisions related to stream regulation and management. ?? 2010 US Government.

The Role of Actin Cytoskeleton in Dendritic Spines in the Maintenance of Long-Term Memory.

PubMed

Basu, Sreetama; Lamprecht, Raphael

2018-01-01

Evidence indicates that long-term memory formation involves alterations in synaptic efficacy produced by modifications in neural transmission and morphology. However, it is not clear how such alterations induced by learning, that encode memory, are maintained over long period of time to preserve long-term memory. This is especially intriguing as the half-life of most of the proteins that underlie such changes is usually in the range of hours to days and these proteins may change their location over time. In this review we describe studies that indicate the involvement of dendritic spines in memory formation and its maintenance. These studies show that learning leads to changes in the number and morphology of spines. Disruption in spines morphology or manipulations that lead to alteration in their number after consolidation are associated with impairment in memory maintenance. We further ask how changes in dendritic spines morphology, induced by learning and reputed to encode memory, are maintained to preserve long-term memory. We propose a mechanism, based on studies described in the review, whereby the actin cytoskeleton and its regulatory proteins involved in the initial alteration in spine morphology induced by learning are also essential for spine structural stabilization that maintains long-term memory. In this model glutamate receptors and other synaptic receptors activation during learning leads to the creation of new actin cytoskeletal scaffold leading to changes in spines morphology and memory formation. This new actin cytoskeletal scaffold is preserved beyond actin and its regulatory proteins turnover and dynamics by active stabilization of the level and activity of actin regulatory proteins within these memory spines.

Microstructural Evolution of Thor™ 115 Creep-Strength Enhanced Ferritic Steel

NASA Astrophysics Data System (ADS)

Ortolani, Matteo; D'Incau, Mirco; Ciancio, Regina; Scardi, Paolo

2017-12-01

A new ferritic steel branded as Thor™ 115 has been developed to enhance high-temperature resistance. The steel design combines an improved oxidation resistance with long-term microstructural stability. The new alloy, cast to different product forms such as plates and tubes, was extensively tested to assess the high-temperature time-dependent mechanical behavior (creep). The main strengthening mechanism is precipitation hardening by finely dispersed carbide and nitride phases. Information on the evolution of secondary phases and time-temperature-precipitation behavior of the alloy, essential to ensure long-term property stability, was obtained by scanning transmission electron microscopy with energy dispersive spectroscopy, and by X-ray Powder Diffraction on specimens aged up to 50,000 hours. A thermodynamic modeling supports presentation and evaluation of the experimental results. The evolution of precipitates in the new alloy confirms the retention of the strengthening by secondary phases, even after long-term exposure at high temperature. The deleterious conversion of nitrides into Z phase is shown to be in line with, or even slower than that of the comparable ASME grade 91 steel.

Long-Term Stability of the NIST Conical Reference Transducer.

PubMed

Fick, Steven E; Proctor, Thomas M

2011-01-01

The National Institute of Standards and Technology (NIST) Conical Reference Transducer (CRT) is designed for purposes requiring frequency response characteristics much more uniform than those attainable with ultrasonic transducers conventionally used for acoustic emission (AE) nondestructive testing. The high performance of the CRT results from the use of design elements radically different from those of conventional transducers. The CRT was offered for sale for 15 years (1985 to 2000). Each CRT was furnished with data which expressed, as a function of frequency, the transducer sensitivity in volts per micrometer of normal displacement on the test block. Of the 22 transducers constructed, eight were reserved for long term research and were stored undisturbed in a laboratory with well controlled temperature and humidity. In 2009, the sensitivities of these eight units were redetermined. The 2009 data have been compared with data from similar tests conducted in 1985. The results of this comparison verify the claim "Results of tests of the long term stability of CRT characteristics indicate that, if proper care is taken, tens of years of service can reasonably be expected." made in the CRT specifications document furnished to prospective customers.

Film Grain-Size Related Long-Term Stability of Inverted Perovskite Solar Cells.

PubMed

Chiang, Chien-Hung; Wu, Chun-Guey

2016-09-22

The power conversion efficiency (PCE) of the perovskite solar cell is high enough to be commercially viable. The next important issue is the stability of the device. This article discusses the effect of the perovskite grain-size on the long-term stability of inverted perovskite solar cells. Perovskite films composed of various sizes of grains were prepared by controlling the solvent annealing time. The grain-size related stability of the inverted cells was investigated both in ambient atmosphere at relative humidity of approximately 30-40 % and in a nitrogen filled glove box (H 2 O<0.1 ppm, O 2 <10 ppm). The PCE of the solar cell based on a perovskite film having the grain size larger than 1 μm (D-10) decreases less than 10 % with storage in a glove box and less than 15 % when it was stored under an ambient atmosphere for 30 days. However, the cell using the perovskite film composed of small (∼100 nm) perovskite grains (D-0) exhibits complete loss of PCE after storage under the ambient atmosphere for only 15 days and a PCE loss of up to 70 % with storage in the glove box for 30 days. These results suggest that, even under H 2 O-free conditions, the chemical- and thermal-induced production of pin holes at the grain boundaries of the perovskite film could be the reason for long-term instability of inverted perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fully Implantable Deep Brain Stimulation System with Wireless Power Transmission for Long-term Use in Rodent Models of Parkinson's Disease.

PubMed

Heo, Man Seung; Moon, Hyun Seok; Kim, Hee Chan; Park, Hyung Woo; Lim, Young Hoon; Paek, Sun Ha

2015-03-01

The purpose of this study to develop new deep-brain stimulation system for long-term use in animals, in order to develop a variety of neural prostheses. Our system has two distinguished features, which are the fully implanted system having wearable wireless power transfer and ability to change the parameter of stimulus parameter. It is useful for obtaining a variety of data from a long-term experiment. To validate our system, we performed pre-clinical test in Parkinson's disease-rat models for 4 weeks. Through the in vivo test, we observed the possibility of not only long-term implantation and stability, but also free movement of animals. We confirmed that the electrical stimulation neither caused any side effect nor damaged the electrodes. We proved possibility of our system to conduct the long-term pre-clinical test in variety of parameter, which is available for development of neural prostheses.

Resveratrol nanosuspensions: interaction of preservatives with nanocrystal production.

PubMed

Kobierski, S; Ofori-Kwakye, K; Müller, R H; Keck, C M

2011-12-01

The effect of six different preservatives on the production process and stability of resveratrol nanosuspensions was investigated. Nanosuspensions of the anti-oxidant resveratrol were prepared by high pressure homogenization (1,500 bar, 20 homogenization cycles). The preservatives used were: caprylyl glycol (0.75%), Euxyl PE 9010 (1.0%), Hydrolite-5 (2.0), Phenonip (0.75%), Rokonsal PB-5 (0.5%) and MultiEx Naturotics (2.0%). Preservation is essential for oral and dermal nanosuspensions, but can impair the stability. The effect of the preservatives on stability as a function of cycle numbers was determined by size measurements (photon correlation spectroscopy (PCS), laser diffraction (LD) and light microscopy). Zeta potential measurements were performed for determination of the Stern potential (measurements in water) and as stability criterion (measurements in original dispersion medium), to elucidate the mechanism of destabilization. The preservatives could be placed into three groups. Hydrolite-5 did not affect the production process and the short term stability, sizes were practically identical to the preservative-free nanosuspension (e.g. PCS diameters 196 nm and 184 nm, respectively). All other preservatives impaired the stability medium to pronounced, being most pronounced for MultiEx Naturotics. Hydrolite-5 is recommended as preservative of choice. A mechanistic model was developed to explain the absence and the different degrees of destabilization. In general, when screening for suitable preservatives, suspensions are produced, different preservatives added and the size changes are monitored over long-term. The destabilizing effect of the preservatives on nanosuspensions became evident when added in the production process immediately, thus this can be used as a screening tool for optimal, non-destabilizing preservatives, replacing or minimizing time-consuming long-term stability studies.

Reactivity of nonaqueous organic electrolytes towards lithium

NASA Technical Reports Server (NTRS)

Shen, D. H.; Subbarao, S.; Deligiannis, F.; Huang, C.-K.; Halpert, G.

1990-01-01

The successful operation of an ambient temperature secondary lithium cell is primarily dependent on the stability of the electrolyte towards lithium. The lithium electrode on open circuit must be inert towards the electrolyte to achieve a long shelf life. The reactivity of tetrahydrofuran and 2-methyltetrahydrofuran based electrolytes with additives such as 2-methylfuran, ethylene carbonate, propylene carbonate, and 3-methylsulfolane was investigated by microcalorimetry and ac impedance spectroscopy techniques. Also the stability of electrolytes by open circuit stand tests was studied. Addition of ethylene carbonate and 2-methylfuran additives was found to improve the stability of tetrahydrofuran and 2-methyltetrahydrofuran based electrolytes. Long term microcalorimetry and ac impedance data clearly confirmed the higher stability of ethylene carbonate/2-methyltetrahydrofuran electrolyte compared to the 2-methyltetrahydrofuran and propylene carbonate/2-methyltetrahydrofuran electrolytes.

Influences on the start, selection and duration of treatment with antibiotics in long-term care facilities

PubMed Central

Daneman, Nick; Campitelli, Michael A.; Giannakeas, Vasily; Morris, Andrew M.; Bell, Chaim M.; Maxwell, Colleen J.; Jeffs, Lianne; Austin, Peter C.; Bronskill, Susan E.

2017-01-01

BACKGROUND: Understanding the extent to which current antibiotic prescribing behaviour is influenced by clinicians’ historical patterns of practice will help target interventions to optimize antibiotic use in long-term care. Our objective was to evaluate whether clinicians’ historical prescribing behaviours influence the start, prolongation and class selection for treatment with antibiotics in residents of long-term care facilities. METHODS: We conducted a retrospective cohort study of all physicians who prescribed to residents in long-term care facilities in Ontario between Jan. 1 and Dec. 31, 2014. We examined variability in antibiotic prescribing among physicians for 3 measures: start of treatment with antibiotics, use of prolonged durations exceeding 7 days and selection of fluoroquinolones. Funnel plots with control limits were used to determine the extent of variation and characterize physicians as extreme low, low, average, high and extreme high prescribers for each tendency. Multivariable logistic regression was used to assess whether a clinician’s prescribing tendency in the previous year predicted current prescribing patterns, after accounting for residents’ demographics, comorbidity, functional status and indwelling devices. RESULTS: Among 1695 long-term care physicians, who prescribed for 93 132 residents, there was wide variability in the start of antibiotic treatment (median 45% of patients, interquartile range [IQR] 32%–55%), use of prolonged treatment durations (median 30% of antibiotic prescriptions, IQR 19%–46%) and selection of fluoroquinolones (median 27% of antibiotic prescriptions, IQR 18%–37%). Prescribing tendencies for antibiotics by physicians in 2014 correlated strongly with tendencies in the previous year. After controlling for individual resident characteristics, prior prescribing tendency was a significant predictor of current practice. INTERPRETATION: Physicians prescribing antibiotics exhibited individual, measurable and historical tendencies toward start of antibiotic treatment, use of prolonged treatment duration and class selection. Prescriber audit and feedback may be a promising tool to optimize antibiotic use in long-term care facilities. PMID:28652480

Influences on the start, selection and duration of treatment with antibiotics in long-term care facilities.

PubMed

Daneman, Nick; Campitelli, Michael A; Giannakeas, Vasily; Morris, Andrew M; Bell, Chaim M; Maxwell, Colleen J; Jeffs, Lianne; Austin, Peter C; Bronskill, Susan E

2017-06-26

Understanding the extent to which current antibiotic prescribing behaviour is influenced by clinicians' historical patterns of practice will help target interventions to optimize antibiotic use in long-term care. Our objective was to evaluate whether clinicians' historical prescribing behaviours influence the start, prolongation and class selection for treatment with antibiotics in residents of long-term care facilities. We conducted a retrospective cohort study of all physicians who prescribed to residents in long-term care facilities in Ontario between Jan. 1 and Dec. 31, 2014. We examined variability in antibiotic prescribing among physicians for 3 measures: start of treatment with antibiotics, use of prolonged durations exceeding 7 days and selection of fluoroquinolones. Funnel plots with control limits were used to determine the extent of variation and characterize physicians as extreme low, low, average, high and extreme high prescribers for each tendency. Multivariable logistic regression was used to assess whether a clinician's prescribing tendency in the previous year predicted current prescribing patterns, after accounting for residents' demographics, comorbidity, functional status and indwelling devices. Among 1695 long-term care physicians, who prescribed for 93 132 residents, there was wide variability in the start of antibiotic treatment (median 45% of patients, interquartile range [IQR] 32%-55%), use of prolonged treatment durations (median 30% of antibiotic prescriptions, IQR 19%-46%) and selection of fluoroquinolones (median 27% of antibiotic prescriptions, IQR 18%-37%). Prescribing tendencies for antibiotics by physicians in 2014 correlated strongly with tendencies in the previous year. After controlling for individual resident characteristics, prior prescribing tendency was a significant predictor of current practice. Physicians prescribing antibiotics exhibited individual, measurable and historical tendencies toward start of antibiotic treatment, use of prolonged treatment duration and class selection. Prescriber audit and feedback may be a promising tool to optimize antibiotic use in long-term care facilities. © 2017 Canadian Medical Association or its licensors.

Soft x ray window encapsulant for HgI2 detectors

NASA Technical Reports Server (NTRS)

Entine, G.; Shah, K.; Squillante, M.

1987-01-01

HgI2 is an excellent semiconductor material for a low energy, room temperature x-ray spectrometer. The high values of the atomic numbers for its constituent elements gives high x-ray and gamma ray stopping power. The band gap of HgI2 is significantly higher than other commonly used semiconductors. Owing to the large value band gap, the leakage current for HgI2 devices is smaller, thus allowing low noise performance. Devices fabricated from HgI2 crystals have demonstrated energy resolution sufficient to distinguish the x-ray emission from the neighboring elements on the periodic table. Also the power requirements of HgI2 are very low. These characteristics make a HgI2 spectrometer an ideal component in a satellite based detection system. Unfortunately, HgI2 crystals tend to deteriorate with time, even if protected by standard semiconductor encapsulants. This degradation ruins the performance of the device in terms of its energy resolution and pulse amplitude. The degrading mechanism is believed to be material loss occurring from below the electrodes, due to high vapor pressure of HgI2 at room temperature. To address this major obstacle to rapid expansion of HgI2 technology, a research program aimed at improving device stability by encapsulation with inert polymeric materials was carried out. The program focused specifically on optimizing the encapsulant materials and their deposition techniques. The principal objectives for this program were device encapsulation, device testing, and accelerated testing to ensure very long term stability of these high resolution sensors. A variety of encapsulants were investigated with the selection criteria based on their chemical diffusion barrier properties, mechanical stability, reactivity, and morphology of encapsulant films. The investigation covered different classes of encapsulants including solvent based encapsulants, vapor deposited encapsulants, and plasma polymerized encapsulants. A variety of characterization techniques were employed to examine their effectiveness in stabilizing HgI2 devices; these included permeability evaluation, vacuum and heat testing, scanning electron microscopy (SEM) as well as studying the detector performance of coated detectors. The plasma polymerized films appear to have entirely solved the HgI2 degradation problem. Another achievement of this program was the development of an accelerated testing technique which correlates extremely well with long term tesing.

Case study comparison of functional vs. organic stability approaches for assessing threat potential at closed landfills in the USA.

PubMed

O'Donnell, Sean T; Caldwell, Michael D; Barlaz, Morton A; Morris, Jeremy W F

2018-05-01

Municipal solid waste (MSW) landfills in the USA are regulated under Subtitle D of the Resource Conservation and Recovery Act (RCRA), which includes the requirement to protect human health and the environment (HHE) during the post-closure care (PCC) period. Several approaches have been published for assessment of potential threats to HHE. These approaches can be broadly divided into organic stabilization, which establishes an inert waste mass as the ultimate objective, and functional stability, which considers long-term emissions in the context of minimizing threats to HHE in the absence of active controls. The objective of this research was to conduct a case study evaluation of a closed MSW landfill using long-term data on landfill gas (LFG) production, leachate quality, site geology, and solids decomposition. Evaluations based on both functional and organic stability criteria were compared. The results showed that longer periods of LFG and leachate management would be required using organic stability criteria relative to an approach based on functional stability. These findings highlight the somewhat arbitrary and overly stringent nature of assigning universal stability criteria without due consideration of the landfill's hydrogeologic setting and potential environmental receptors. This supports previous studies that advocated for transition to a passive or inactive control stage based on a performance-based functional stability framework as a defensible mechanism for optimizing and ending regulatory PCC. Copyright © 2018 Elsevier Ltd. All rights reserved.

Psychometric properties and norms of the German ABC-Community and PAS-ADD Checklist.

PubMed

Zeilinger, Elisabeth L; Weber, Germain; Haveman, Meindert J

2011-01-01

The aim of the present study was to standardize and generate psychometric evidence of the German language versions of two well-established English language mental health instruments: the Aberrant Behavior Checklist-Community (ABC-C) and the Psychiatric Assessment Schedule for Adults with Developmental Disabilities (PAS-ADD) Checklist. New methods in this field were introduced: a simulation method for testing the factor structure and an exploration of long-term stability over two years. The checklists were both administered to a representative sample of 270 individuals with intellectual disability (ID) and, two years later in a second data collection, to 128 participants of the original sample. Principal component analysis and parallel analysis were performed. Reliability measures, long-term stability, subscale intercorrelations, as well as standardized norms were generated. Prevalence of mental health problems was examined. Psychometric properties were mostly excellent, with long-term stability showing moderate to strong effects. The original factor structure of the ABC-C was replicated. PAS-ADD Checklist produced a similar, but still different structure compared with findings from the English language area. The overall prevalence rate of mental health problems in the sample was about 20%. Considering the good results on the measured psychometric properties, the two checklists are recommended for the early detection of mental health problems in persons with ID. Copyright © 2011 Elsevier Ltd. All rights reserved.

Activity and Stability of (Pr 1-xNd x) 2NiO 4+δ as Cathodes for Oxide Fuel Cells: Part VI. The Role of Cu Dopant on the Structure and Electrochemical Properties

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

Dogdibegovic, Emir; Yan, Jingbo; Cai, Qinsheng

Phase instability in praseodymium nickelates is a major concern for the long-term operations of solid oxide fuel cells since it may lead to the performance degradation. In this work, praseodymium nickelates (ex. Pr 2NiO 4+δ) have been stabilized via substitution on both Pr- and Ni-sites. Systematic studies over a wide range of compositions were conducted via long-term thermal annealing studies (T ≤ 870°C) and electrochemical tests in full cells. Proposed (Pr 0.50Nd 0.50) 2Ni 1-yCu yO 4+δ compositions (y = 0.05, 0.10, 0.20, and 0.30) showed the most promising results and serve as a comprehensive extension to our previous studiesmore » in this series of papers. A stable long-term performance was obtained for temperatures up to 790°C for 500 hours at 0.80 V with a minimal tradeoff between the activity (power density of 0.8–1.0 W cm -2 at 850°C) and performance stability. A preserved parent phase and suppressed performance degradation, when compared to Pr 2NiO 4+δ, make newly developed electrodes attractive candidates for the state-of-the-art solid oxide fuel cell applications.« less

Characterization of the Sonoran desert as a radiometric calibration target for Earth observing sensors

USGS Publications Warehouse

Angal, Amit; Chander, Gyanesh; Xiong, Xiaoxiong; Choi, Tae-young; Wu, Aisheng

2011-01-01

To provide highly accurate quantitative measurements of the Earth's surface, a comprehensive calibration and validation of the satellite sensors is required. The NASA Moderate Resolution Imaging Spectroradiometer (MODIS) Characterization Support Team, in collaboration with United States Geological Survey, Earth Resources Observation and Science Center, has previously demonstrated the use of African desert sites to monitor the long-term calibration stability of Terra MODIS and Landsat 7 (L7) Enhanced Thematic Mapper plus (ETM+). The current study focuses on evaluating the suitability of the Sonoran Desert test site for post-launch long-term radiometric calibration as well as cross-calibration purposes. Due to the lack of historical and on-going in situ ground measurements, the Sonoran Desert is not usually used for absolute calibration. An in-depth evaluation (spatial, temporal, and spectral stability) of this site using well calibrated L7 ETM+ measurements and local climatology data has been performed. The Sonoran Desert site produced spatial variability of about 3 to 5% in the reflective solar regions, and the temporal variations of the site after correction for view-geometry impacts were generally around 3%. The results demonstrate that, barring the impacts due to occasional precipitation, the Sonoran Desert site can be effectively used for cross-calibration and long-term stability monitoring of satellite sensors, thus, providing a good test site in the western hemisphere.

Treatment outcome and long-term stability of skeletal changes following maxillary distraction in adult subjects of cleft lip and palate

PubMed Central

Singh, Satinder Pal; Jena, Ashok Kumar; Rattan, Vidya; Utreja, Ashok Kumar

2012-01-01

Aim: To evaluate the treatment outcome and long-term stability of skeletal changes following maxillary advancement with distraction osteogenesis in adult subjects of cleft lip and palate. Materials and Methods: Total 12 North Indian adult patients in the age range of 17-34 years with cleft lip and palate underwent advancement of maxilla by distraction osteogenesis. Lateral cephalograms recorded prior to distraction, at the end of distraction, 6 months after distraction, and at least 24 months (mean 25.5 ± 1.94 months) after distraction osteogenesis were used for the evaluation of treatment outcome and long-term stability of the skeletal changes. Descriptive analysis, ANOVA, and post-hoc test were used, and P-value 0.05 was considered as a statistically significant level. Results: Maxillary distraction resulted in significant advancement of maxilla (P<0.001). Counterclockwise rotation of the palatal plane took place after maxillary distraction. The position of the mandible and facial heights were stable during distraction. During the first 6 months of the post-distraction period, the maxilla showed relapse of approximately 30%. However, after 6 months post distraction, the relapse was very negligible. Conclusions: Successful advancement of maxilla was achieved by distraction osteogenesis in adult subjects with cleft lip and palate. Most of the relapse occurred during the first 6 months of post-distraction period, and after that the outcomes were stable. PMID:22919221

Treatment outcome and long-term stability of skeletal changes following maxillary distraction in adult subjects of cleft lip and palate.

PubMed

Singh, Satinder Pal; Jena, Ashok Kumar; Rattan, Vidya; Utreja, Ashok Kumar

2012-04-01

To evaluate the treatment outcome and long-term stability of skeletal changes following maxillary advancement with distraction osteogenesis in adult subjects of cleft lip and palate. Total 12 North Indian adult patients in the age range of 17-34 years with cleft lip and palate underwent advancement of maxilla by distraction osteogenesis. Lateral cephalograms recorded prior to distraction, at the end of distraction, 6 months after distraction, and at least 24 months (mean 25.5 ± 1.94 months) after distraction osteogenesis were used for the evaluation of treatment outcome and long-term stability of the skeletal changes. Descriptive analysis, ANOVA, and post-hoc test were used, and P-value 0.05 was considered as a statistically significant level. Maxillary distraction resulted in significant advancement of maxilla (P<0.001). Counterclockwise rotation of the palatal plane took place after maxillary distraction. The position of the mandible and facial heights were stable during distraction. During the first 6 months of the post-distraction period, the maxilla showed relapse of approximately 30%. However, after 6 months post distraction, the relapse was very negligible. Successful advancement of maxilla was achieved by distraction osteogenesis in adult subjects with cleft lip and palate. Most of the relapse occurred during the first 6 months of post-distraction period, and after that the outcomes were stable.

Activity and Stability of (Pr 1-xNd x) 2NiO 4+δ as Cathodes for Oxide Fuel Cells: Part VI. The Role of Cu Dopant on the Structure and Electrochemical Properties

DOE PAGES

Dogdibegovic, Emir; Yan, Jingbo; Cai, Qinsheng; ...

2017-08-12

Phase instability in praseodymium nickelates is a major concern for the long-term operations of solid oxide fuel cells since it may lead to the performance degradation. In this work, praseodymium nickelates (ex. Pr 2NiO 4+δ) have been stabilized via substitution on both Pr- and Ni-sites. Systematic studies over a wide range of compositions were conducted via long-term thermal annealing studies (T ≤ 870°C) and electrochemical tests in full cells. Proposed (Pr 0.50Nd 0.50) 2Ni 1-yCu yO 4+δ compositions (y = 0.05, 0.10, 0.20, and 0.30) showed the most promising results and serve as a comprehensive extension to our previous studiesmore » in this series of papers. A stable long-term performance was obtained for temperatures up to 790°C for 500 hours at 0.80 V with a minimal tradeoff between the activity (power density of 0.8–1.0 W cm -2 at 850°C) and performance stability. A preserved parent phase and suppressed performance degradation, when compared to Pr 2NiO 4+δ, make newly developed electrodes attractive candidates for the state-of-the-art solid oxide fuel cell applications.« less

Long-term care information systems: an overview of the selection process.

PubMed

Nahm, Eun-Shim; Mills, Mary Etta; Feege, Barbara

2006-06-01

Under the current Medicare Prospective Payment System method and the ever-changing managed care environment, the long-term care information system is vital to providing quality care and to surviving in business. system selection process should be an interdisciplinary effort involving all necessary stakeholders for the proposed system. The system selection process can be modeled following the Systems Developmental Life Cycle: identifying problems, opportunities, and objectives; determining information requirements; analyzing system needs; designing the recommended system; and developing and documenting software.

Development of Stable Liquid Glucagon Formulations for Use in Artificial Pancreas

PubMed Central

Li, Ming; Krasner, Alan; De Souza, Errol

2014-01-01

Background: A promising approach to treat diabetes is the development of fully automated artificial/bionic pancreas systems that use both insulin and glucagon to maintain euglycemia. A physically and chemically stable liquid formulation of glucagon does not currently exist. Our goal is to develop a glucagon formulation that is stable as a clear and gel-free solution, free of fibrils and that has the requisite long-term shelf life for storage in the supply chain, short-term stability for at least 7 days at 37°C, and pump compatibility for use in a bihormonal pump. Methods: We report the development of two distinct families of stable liquid glucagon formulations which utilize surfactant or surfactant-like excipients (LMPC and DDM) to “immobilize” the glucagon in solution potentially through the formation of micelles and prevention of interaction between glucagon molecules. Results: Data are presented that demonstrate long-term physical and chemical stability (~2 years) at 5°C, short-term stability (up to 1 month) under accelerated 37°C testing conditions, pump compatibility for up to 9 days, and adequate glucose responses in dogs and diabetic swine. Conclusions: These stable glucagon formulations show utility and promise for further development in artificial pancreas systems. PMID:25352634

77 FR 22772 - Environmental Management Site-Specific Advisory Board

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-17

... and environmental restoration; waste management and disposition; stabilization and disposition of non-stockpile nuclear materials; excess facilities; future land use and long-term stewardship; risk assessment...

The use of atypical antipsychotics beyond psychoses: efficacy of quetiapine in bipolar disorder.

PubMed

Mundo, Emanuela; Cattaneo, Elisabetta; Zanoni, Silvia; Altamura, A Carlo

2006-06-01

Atypical antpsychotics have been sucessfully used in the treatment of bipolar disorder (BD), either as adjunctive or as monotherapy. Quetiapine is an atypical antipsychotic extensively used in the treatment of psychotic disorders. It has serotonergic and dopaminergic activity and it appears to be selective for the mesolimbic and mesocortical dopamine system. The aim of this paper was to review the recent literature on the use of quetiapine in the treatment of BD. The literature databases currently available online were searched for papers on quetiapine and BD. Papers and reports published between January 1995 and June 2005 were selected and reviewed critically. Augmentative low dose quetiapine was found to be effective in BD partially responsive to conventional mood-stabilizers. Manic and mixed episodes have been the best studied, and quetiapine was found to be effective either as monotherapy or as adjunctive therapy in both randomized clinical trials and open-label studies. Data on the use of quetiapine in bipolar depression showed a significant efficacy and high remission rates. Maintenance data suggested a role of quetiapine as a good alternative to classical mood stabilizers in reducing recurrence rates of BD. A few studies on the efficacy in rapid cycling BD have also been published. Quetiapine is an effective agent for the short- and long-term treatment of BD. The mechanism of action of quetiapine as a mood stabilizer is still unknown. Some preliminary data suggest the involvement of glutamate pathways but further studies are needed to clarify this issue.

Wide abdominal rectus plication abdominoplasty for the treatment of chronic intractable low back pain.

PubMed

Oneal, Robert M; Mulka, Joseph P; Shapiro, Paul; Hing, David; Cavaliere, Christi

2011-01-01

A previous report demonstrated that the wide abdominal rectus plication abdominoplasty is an effective treatment modality in select patients with low back pain who failed to achieve relief with conservative therapy. The authors studied eight female patients who presented with chronic low back pain and marked lower abdominal wall muscular laxity. All had failed to respond to conservative management for their chronic back pain. They all underwent wide abdominal rectus plication abdominoplasty. Patient selection and details of the procedure are discussed. There were no significant complications in this series, and all the patients had prompt and prolonged alleviation of their back pain. Length of follow-up ranged from 2 to 11 years. Changes in the biomechanics of the lower abdominal musculature as a result of the wide abdominal rectus plication abdominoplasty are discussed in the context of increasing spinal stability, leading to an alleviation of chronic low back pain. An argument is made that this abdominoplasty procedure produces a spine-stabilizing effect by (1) tightening the muscles of the lateral abdominal complex and thus increasing intraabdominal pressure and (2) increasing the efficiency of these muscles so that their effectiveness as spine stabilizers is increased. Even though this is a small series, the fact that all the patients sustained long-term alleviation of their preoperative chronic back pain suggests that the wide abdominal rectus plication abdominoplasty should be considered as an option for patients with weak lower abdominal muscles and intractable low back pain who have failed conservative management.

Impairment of hypoxia-induced HIF-1α signaling in keratinocytes and fibroblasts by sulfur mustard is counteracted by a selective PHD-2 inhibitor.

PubMed

Deppe, Janina; Popp, Tanja; Egea, Virginia; Steinritz, Dirk; Schmidt, Annette; Thiermann, Horst; Weber, Christian; Ries, Christian

2016-05-01

Skin exposure to sulfur mustard (SM) provokes long-term complications in wound healing. Similar to chronic wounds, SM-induced skin lesions are associated with low levels of oxygen in the wound tissue. Normally, skin cells respond to hypoxia by stabilization of the transcription factor hypoxia-inducible factor 1 alpha (HIF-1α). HIF-1α modulates expression of genes including VEGFA, BNIP3, and MMP2 that control processes such as angiogenesis, growth, and extracellular proteolysis essential for proper wound healing. The results of our studies revealed that exposure of primary normal human epidermal keratinocytes (NHEK) and primary normal human dermal fibroblasts (NHDF) to SM significantly impaired hypoxia-induced HIF-1α stabilization and target gene expression in these cells. Addition of a selective inhibitor of the oxygen-sensitive prolyl hydroxylase domain-containing protein 2 (PHD-2), IOX2, fully recovered HIF-1α stability, nuclear translocation, and target gene expression in NHEK and NHDF. Moreover, functional studies using a scratch wound assay demonstrated that the application of IOX2 efficiently counteracted SM-mediated deficiencies in monolayer regeneration under hypoxic conditions in NHEK and NHDF. Our findings describe a pathomechanism by which SM negatively affects hypoxia-stimulated HIF-1α signaling in keratinocytes and fibroblasts and thus possibly contributes to delayed wound healing in SM-injured patients that could be treated with PHD-2 inhibitors.

Soil structural stability assessment with the fluidized bed, aggregate stability, and rainfall simulation on long-term tillage and crop rotation systems

USDA-ARS?s Scientific Manuscript database

The formation of stable soil aggregates is an important indicator of soil susceptibility to erosion and a factor defining soil health. On cropland, tillage practices and crop rotations have shown to control soil biophysical properties with potential consequences on erosion susceptibility. Thus, the ...

Long-Term Stability of Core Language Skill in Children with Contrasting Language Skills

ERIC Educational Resources Information Center

Bornstein, Marc H.; Hahn, Chun-Shin; Putnick, Diane L.

2016-01-01

This 4-wave longitudinal study evaluated stability of core language skill in 421 European American and African American children, half of whom were identified as low (n = 201) and half of whom were average-to-high (n = 220) in later language skill. Structural equation modeling supported loadings of multivariate age-appropriate multisource measures…

Ceramics breakthrough

NASA Astrophysics Data System (ADS)

Shim, Joon Hyung

2018-03-01

Protonic ceramic fuel cells (PCFCs) are a potential alternative to solid oxide fuel cells at temperatures below 600 °C, but they suffer from low power output and poor chemical stability. Now, PCFCs with a power density of over 500 mW per cm2 at 500 °C and long-term stability are demonstrated using optimized perovskite-based electrolyte and electrodes.

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

Declining sediment loads from Redwood Creek and the Klamath River, north coastal California

Treesearch

Randy D. Klein; Jeffrey K. Anderson

2012-01-01

River basin sediment loads are affected by several factors, with flood magnitude and watershed erosional stability playing dominant and dynamic roles. Long-term average sediment loads for northern California river basins have been computed by several researchers by several methods. However, characterizing the dynamic nature of climate and watershed stability requires...

Academic Functioning and Mental Health in Adolescence: Patterns, Progressions, and Routes from Childhood.

ERIC Educational Resources Information Center

Roeser, Robert W.; Eccles, Jacquelynne S.; Freedman-Doan, Carol

1999-01-01

Examined patterns of academic functioning and mental health in middle school students and the relation of such patterns to their prior and subsequent functioning. Found variegated patterns of academic and emotional functioning at eighth grade and stability in these patterns across the high school transition. Found some long-term stability among…

[The influence of the stapes prosthesis on the long-term results of stapedectomy (author's transl)].

PubMed

Schöndorf, J; Pilorget, J; Gräber, S

1980-05-01

In comparing two groups of patients following stapedectomies, significantly better long-term results were obtained by using the Robinson steel piston prosthesis (n = 85) as opposed to the wire prosthesis (n = 74). By so doing, the impairment of sound transmission was reduced and the Carhart depression counterbalanced. This improvement is thought to result from the increased mass and stability of the steel prosthesis as well as from its more correct anatomical positioning.

Composite membranes for alkaline electrolysis based on polysulfone and mineral fillers

NASA Astrophysics Data System (ADS)

Burnat, Dariusz; Schlupp, Meike; Wichser, Adrian; Lothenbach, Barbara; Gorbar, Michal; Züttel, Andreas; Vogt, Ulrich F.

2015-09-01

Mineral-based membranes for high temperature alkaline electrolysis were developed by a phase inversion process with polysulfone as binder. The long-term stability of new mineral fillers: wollastonite, forsterite and barite was assessed by 8000 h-long leaching experiments (5.5 M KOH, 85 °C) combined with thermodynamic modelling. Barite has released only 6.22 10-4 M of Ba ions into the electrolyte and was selected as promising filler material, due to its excellent stability. Barite-based membranes, prepared by the phase inversion process, were further studied. The resistivity of these membranes in 5.5 M KOH was investigated as a function of membrane thickness and total porosity, hydrodynamic porosity as well as gas purities determined by conducting electrolysis at ambient conditions. It was found that a dense top layer resulting from the phase inversion process, shows resistivity values up to 451.0 ± 22 Ω cm, which is two orders of magnitude higher than a porous bulk membrane microstructure (3.89 Ω cm). Developed membranes provided hydrogen purity of 99.83 at 200 mA cm-2, which is comparable to previously used chrysotile membranes and higher than commercial state-of-the-art Zirfon 500utp membrane. These cost-effective polysulfone - barite membranes are promising candidates as asbestos replacement for commercial applications.

Development of a novel pH sensor based upon Janus Green B immobilized on triacetyl cellulose membrane: Experimental design and optimization.

PubMed

Chamkouri, Narges; Niazi, Ali; Zare-Shahabadi, Vali

2016-03-05

A novel pH optical sensor was prepared by immobilizing an azo dye called Janus Green B on the triacetylcellulose membrane. Condition of the dye solution used in the immobilization step, including concentration of the dye, pH, and duration were considered and optimized using the Box-Behnken design. The proposed sensor showed good behavior and precision (RSD<5%) in the pH range of 2.0-10.0. Advantages of this optical sensor include on-line applicability, no leakage, long-term stability (more than 6 months), fast response time (less than 1 min), high selectivity and sensitivity as well as good reversibility and reproducibility. Copyright © 2015. Published by Elsevier B.V.

Dual liquid and gas chromatograph system

DOEpatents

Gay, D.D.

A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

Dual liquid and gas chromatograph system

DOEpatents

Gay, Don D.

1985-01-01

A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

Sub-kilohertz excitation lasers for quantum information processing with Rydberg atoms

NASA Astrophysics Data System (ADS)

Legaie, Remy; Picken, Craig J.; Pritchard, Jonathan D.

2018-04-01

Quantum information processing using atomic qubits requires narrow linewidth lasers with long-term stability for high fidelity coherent manipulation of Rydberg states. In this paper, we report on the construction and characterization of three continuous-wave (CW) narrow linewidth lasers stabilized simultaneously to an ultra-high finesse Fabry-Perot cavity made of ultra-low expansion (ULE) glass, with a tunable offset-lock frequency. One laser operates at 852~nm while the two locked lasers at 1018~nm are frequency doubled to 509~nm for excitation of $^{133}$Cs atoms to Rydberg states. The optical beatnote at 509~nm is measured to be 260(5)~Hz. We present measurements of the offset between the atomic and cavity resonant frequencies using electromagnetically induced transparency (EIT) for high-resolution spectroscopy on a cold atom cloud. The long-term stability is determined from repeated spectra over a period of 20 days yielding a linear frequency drift of $\\sim1$~Hz/s.

Metallic corrosion processes reactivation sustained by iron-reducing bacteria: Implication on long-term stability of protective layers

NASA Astrophysics Data System (ADS)

Esnault, L.; Jullien, M.; Mustin, C.; Bildstein, O.; Libert, M.

In deep geological environments foreseen for the disposal of radioactive waste, metallic containers will undergo anaerobic corrosion. In this context, the formation of corrosion products such as magnetite may reduce the rate of corrosion processes through the formation of a protective layer. This study aims at determining the direct impact of iron-reducing bacteria (IRB) activity on the stability of corrosion protective layers. Batch experiments investigating iron corrosion processes including the formation of secondary magnetite and its subsequent alteration in the presence of IRB show the bacteria ability to use structural Fe(III) for respiration which leads to the sustainment of a high corrosion rate. With the bio-reduction of corrosion products such as magnetite, and H 2 as electron donor, IRB promote the reactivation of corrosion processes in corrosive environments by altering the protective layer. This phenomenon could have a major impact on the long-term stability of metallic compounds involved in multi-barrier system for high-level radioactive waste containment.

Cleft maxillary distraction versus orthognathic surgery--which one is more stable in 5 years?

PubMed

Chua, Hannah Daile P; Hägg, Margareta Bendeus; Cheung, Lim Kwong

2010-06-01

The objective of this study was to compare the long-term stability of distraction osteogenesis (DO) and conventional orthognathic surgery (CO) in patients with cleft lip and palate (CLP). CLP patients requiring maxillary advancement of 4 to 10 mm were randomized and assigned to either CO or DO. In the CO group, the maxilla was fully mobilized to the preplanned position and fixed using titanium miniplates. In the DO group, the maxilla was mobilized to a limited extent and distractors were fixed on each side of the maxilla. Serial lateral cephalographs were taken for the assessment of stability at different postoperative periods up to 5 years. In the CO group, the maxilla relapsed backward and upward, whereas in the DO group, it advanced more forward and downward over 5 years. Distraction of the cleft maxilla can achieve better long-term skeletal stability in maintaining its advanced position than CO. Copyright 2010 Mosby, Inc. All rights reserved.

Influence of processing factors on the stability of model mayonnaise with whole egg during long-term storage.

PubMed

Ariizumi, Masahiro; Kubo, Megumi; Handa, Akihiro; Hayakawa, Takashi; Matsumiya, Kentaro; Matsumura, Yasuki

2017-04-01

Mayonnaise-like oil-in-water emulsions with different stabilities-evaluated from the degree of macroscopic defects, e.g., syneresis-were prepared by different formulations and processing conditions (egg yolk weight, homogenizer speed, and vegetable oil temperature). Emulsions prepared with lower egg yolk content were destabilized for shorter periods. The long-term stability of emulsions was weakly related to initial properties, e.g., oil droplet distribution and protein coverage at the interface. Protein aggregation between oil droplets was observed and would be responsible for the instability of emulsions exhibited by the appearance defects. SDS-PAGE results for adsorbed and unadsorbed proteins at the O/W interface suggested that predominant constituents adsorbed onto the interface were egg white proteins as compared with egg yolk components when the amount of added egg yolk was low. In present condition, egg white proteins adsorbed at the O/W interface could be a bridge of neighboring oil droplets thereby causing flocculation in emulsions.

Mechanical properties and microstructural evolution of modified 9Cr-1Mo steel after long-term aging for 50,000 h

NASA Astrophysics Data System (ADS)

Baek, Jong-Hyuk; Kim, Sung-Ho; Lee, Chan-Bock; Hahn, Do-Hee

2009-08-01

The mechanical properties and microstructural evolution of modified 9Cr-1Mo steel have been studied to investigate steel property changes after long-term isothermal aging at 600 °C for 50,000 h. The microhardness and strength were maintained constantly after aging but the impact energy was dramatically reduced by 62 % during the aging period. From the viewpoint of microstructural evolution after the aging process, Cr-enrichment and Fe-depletion took place within the M23C6-type precipitates in the as-aged steel and V-depletion also happened within the VX-type precipitates after aging. In addition, the precipitates of the M2Mo-type Laves phase and the segregation of the impurity atoms would be formed during the long-term aging period. It was considered that the sharp reduction of the impact energy could be related to the formation of the Laves phases and the impurity segregation after aging at 600 °C. The phase stability was also verified by the specific heat results up to 950 °C from a DSC test. It was concluded from this study that the modified 9Cr-1Mo steel would keep its microstructural stability at 600 °C during the long-term aging period of 50,000 h, which was equivalent to the in-service life of the SFR fuel cladding.

Ten-year stability of self-reported schizotypal personality features in patients with psychosis and their healthy siblings.

PubMed

Moreno-Izco, Lucía; Sánchez-Torres, Ana M; Lorente-Omeñaca, Ruth; Fañanás, Lourdes; Rosa, Araceli; Salvatore, Paola; Peralta, Victor; Cuesta, Manuel J

2015-06-30

Schizotypal personality disorder (SPD) symptoms or features are common in patients with psychosis and their healthy relatives. However, the long-term stability of these SPD features and therefore their constituting enduring traits underlying vulnerability to psychosis remain to be clarified. Thirty-two patients with psychotic disorders and 29 of their healthy siblings were included from the long-term follow-up study of 89 nuclear families. Participants were clinically assessed by means of a semi-structured diagnostic interview, whereas the Schizotypal Personality Questionnaire-Brief (SPQ-B) was applied for the self-assessment of SPD symptoms. The assessments were carried out upon admission to the study and at follow-up, about 10 years later. The patients had higher scores than their siblings on the SPQ-B both at baseline and follow-up. In addition, self-reported SPD symptoms remained stable over time in total scores and in all the SPQ-B subscores, except for the SPQ-B Disorganization subscale. Self-reported SPD symptoms were stable over the long term among patients with psychotic disorders and their healthy siblings. This finding provides new support for including the SPD construct as a trait measure for studies addressing both vulnerability to psychosis in first-degree relatives of patients with psychosis and long-term persistence of symptoms in patients suffering from psychosis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A new class of long-term stable lunar resonance orbits: Space weather applications and the Interstellar Boundary Explorer

NASA Astrophysics Data System (ADS)

McComas, D. J.; Carrico, J. P.; Hautamaki, B.; Intelisano, M.; Lebois, R.; Loucks, M.; Policastri, L.; Reno, M.; Scherrer, J.; Schwadron, N. A.; Tapley, M.; Tyler, R.

2011-11-01

NASA's Interstellar Boundary Explorer (IBEX) mission was recently maneuvered into a unique long-term stable Earth orbit, with apogee at ˜50 Earth radii (RE). The Moon's (˜65 RE) gravity disrupts most highly elliptical Earth orbits, leading to (1) chaotic orbital solutions, (2) the inability to predict orbital positions more than a few years into the future, and ultimately (3) mission-ending possibilities of atmospheric reentry or escape from Earth orbit. By synchronizing the satellite's orbital period to integer fractions of the Moon's sidereal period, PM = 27.3 days (e.g., PM/2 = 13.6 days, PM/3 = 9.1 days), and phasing apogee to stay away from the Moon, very long term stability can be achieved. Our analysis indicates orbital stability for well over a decade, and these IBEX-like orbits represent a new class of Earth orbits that are stable far longer than typical satellite lifetimes. These orbits provide cost-effective and nearly ideal locations for long-term space weather observations from spacecraft that can remotely image the Earth's magnetosphere from outside its boundaries while simultaneously providing external (solar wind or magnetosheath) observation over most of their orbits. Utilized with multiple spacecraft, such orbits would allow continuous and simultaneous monitoring of the magnetosphere in order to help predict and mitigate adverse space weather-driven effects.

Association of the canine guidance angle with maxillary and mandibular intercanine widths and anterior alignment relapse: Extraction vs nonextraction treatment.

PubMed

Heiser, Wolfgang; Richter, Martin; Niederwanger, Andreas; Neunteufel, Nikolaus; Kulmer, Siegfried

2008-05-01

Long-term stability is an important measure of the success of orthodontic treatment. Research in the 1970s suggested that premolar extraction treatment had poor stability over the long term. The purpose of this prospective follow-up study was to investigate changes in intercanine widths and the irregularity index during the postretention phase in patients treated with and without extractions. Associations between the maxillary canine guidance angle and the mandibular intercanine widths and the mandibular irregularity index were also examined. Two groups of 30 patients each, with and without premolar extractions, were studied and the results compared. Records were taken at pretreatment, at bracket removal, at the end of retention, and out of retention. The times out of retention were 6.3 years for the nonextraction group and 6.5 years for the extraction group. Stone casts were mounted on an articulator with an anatomical facebow and a central wax record. The measurements were made with a 3-dimensional digitizer. Maxillary and mandibular intercanine distances behaved differently. The mandibular intercanine distance showed a net decrease between pretreatment and follow-up, whereas the maxillary arch had a net increase. The maxillary canine guidance angle at the end of retention, measured to the axis-orbital plane, was highly associated with relapse of mandibular anterior alignment and change of the mandibular intercanine distance. Methods are needed that consider the anatomical configuration of the teeth for bracket selection before treatment. Individualized brackets (torque) should then be coordinated with the guidance angle of the maxillary teeth.

Performance mapping of a 30 cm engineering model thruster

NASA Technical Reports Server (NTRS)

Poeschel, R. L.; Vahrenkamp, R. P.

1975-01-01

A 30 cm thruster representative of the engineering model design has been tested over a wide range of operating parameters to document performance characteristics such as electrical and propellant efficiencies, double ion and beam divergence thrust loss, component equilibrium temperatures, operational stability, etc. Data obtained show that optimum power throttling, in terms of maximum thruster efficiency, is not highly sensitive to parameter selection. Consequently, considerations of stability, discharge chamber erosion, thrust losses, etc. can be made the determining factors for parameter selection in power throttling operations. Options in parameter selection based on these considerations are discussed.

Hg(+) Frequency Standards

NASA Technical Reports Server (NTRS)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

2000-01-01

In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

PHYSICAL AND CHEMICAL STABILITY ANALYSIS OF COSMETIC MULTI- PLE EMULSIONS LOADED WITH ASCORBYL PALMITATE AND SODIUM ASCORBYL PHOSPHATE SALTS.

PubMed

Khan, Hira; Akhtar, Naveed; Ali, Atif; Khan, Haji M Shoaib; Sohail, Muhammad; Naeem, Muhammad; Nawaz, Zarqa

2016-09-01

Stability of hydrophilic and lipophilic vitamin C derivatives for quenching synergistic antioxidant activities and to treat oxidative related diseases is a major issue. This study was aimed to encapsulate hydrophilic and lipophilic vitamin C derivatives (ascorbyl palmitate and sodium ascorbyl phosphate) as functional ingredients in a newly formulated multiple emulsion of the W//W type to attain the synergistic antioxidant effects and the resultant system's long term physical and chemical stability. Several multiple emulsions using the same concentration of emulsifiers but different concentrations of ascorbyl palmitate and sodium ascorbyl phosphate were developed. Three finally selected multiple emulsions (ME₁, ME₂ and ME₃) were evaluated for physical stability in terms of rheology, microscopy, conductivity, pH, and organoleptic characteristics under different storage conditions for 3 months. Chemical stability was determined by HPLC on Sykam GmbH HPLC system (Germany), equipped with a variable UV detector. Results showed that at accelerated storage conditions all the three multiple emulsions had shear thinning behavior of varying shear stress with no influence of location of functional ingredients in a carrier system. Conductivity values increased and pH values remained within the skin pH range for 3 months. Microscopic analysis showed an increase in globule size with the passage of time, especially at higher temperatures while decreased at low temperatures. Centrifugation test did not cause phase separation till the 45th day, but little effects after 2 months. Chemical stability analysis by HPLC at the end of 3 months showed that ascorbyl palmitate and sodium ascorbyl phosphate were almost stable in all multiple emulsions with no influence of their location in a carrier system. Multiple emulsions were found a stable carrier for hydrophilic and lipophilic vitamin C derivatives to enhance their desired effects. Considering that many topical formulations contain simple vitamin C it is suggested that present study may contribute to the development of more stable formulations with a combination of vitamin C derivatives to enhance their cosmetic benefits.

The Long-Term Effectiveness of a Selective, Personality-Targeted Prevention Program in Reducing Alcohol Use and Related Harms: A Cluster Randomized Controlled Trial

ERIC Educational Resources Information Center

Newton, Nicola C.; Conrod, Patricia J.; Slade, Tim; Carragher, Natacha; Champion, Katrina E.; Barrett, Emma L.; Kelly, Erin V.; Nair, Natasha K.; Stapinski, Lexine; Teesson, Maree

2016-01-01

Background: This study investigated the long-term effectiveness of Preventure, a selective personality-targeted prevention program, in reducing the uptake of alcohol, harmful use of alcohol, and alcohol-related harms over a 3-year period. Methods: A cluster randomized controlled trial was conducted to assess the effectiveness of Preventure.…

The Glyphosate-Based Herbicide Roundup Does not Elevate Genome-Wide Mutagenesis of Escherichia coli.

PubMed

Tincher, Clayton; Long, Hongan; Behringer, Megan; Walker, Noah; Lynch, Michael

2017-10-05

Mutations induced by pollutants may promote pathogen evolution, for example by accelerating mutations conferring antibiotic resistance. Generally, evaluating the genome-wide mutagenic effects of long-term sublethal pollutant exposure at single-nucleotide resolution is extremely difficult. To overcome this technical barrier, we use the mutation accumulation/whole-genome sequencing (MA/WGS) method as a mutagenicity test, to quantitatively evaluate genome-wide mutagenesis of Escherichia coli after long-term exposure to a wide gradient of the glyphosate-based herbicide (GBH) Roundup Concentrate Plus. The genome-wide mutation rate decreases as GBH concentration increases, suggesting that even long-term GBH exposure does not compromise the genome stability of bacteria. Copyright © 2017 Tincher et al.

The impact of logging on biodiversity and carbon sequestration in tropical forests

NASA Astrophysics Data System (ADS)

Cazzolla Gatti, R.

2012-04-01

Tropical deforestation is one of the most relevant environmental issues at planetary scale. Forest clearcutting has dramatic effect on local biodiversity, on the terrestrial carbon sink and atmospheric GHGs balance. In terms of protection of tropical forests selective logging is, instead, often regarded as a minor or even positive management practice for the ecosystem and it is supported by international certifications. However, few studies are available on changes in the structure, biodiversity and ecosystem services due to the selective logging of African forests. This paper presents the results of a survey on tropical forests of West and Central Africa, with a comparison of long-term dynamics, structure, biodiversity and ecosystem services (such as the carbon sequestration) of different types of forests, from virgin primary to selectively logged and secondary forest. Our study suggests that there is a persistent effect of selective logging on biodiversity and carbon stock losses in the long term (up to 30 years since logging) and after repeated logging. These effects, in terms of species richness and biomass, are greater than the expected losses from commercial harvesting, implying that selective logging in West and Central Africa is impairing long term (at least until 30 years) ecosystem structure and services. A longer selective logging cycle (>30 years) should be considered by logging companies although there is not yet enough information to consider this practice sustainable.

Predicting rates of inbreeding in populations undergoing selection.

PubMed Central

Woolliams, J A; Bijma, P

2000-01-01

Tractable forms of predicting rates of inbreeding (DeltaF) in selected populations with general indices, nonrandom mating, and overlapping generations were developed, with the principal results assuming a period of equilibrium in the selection process. An existing theorem concerning the relationship between squared long-term genetic contributions and rates of inbreeding was extended to nonrandom mating and to overlapping generations. DeltaF was shown to be approximately (1)/(4)(1 - omega) times the expected sum of squared lifetime contributions, where omega is the deviation from Hardy-Weinberg proportions. This relationship cannot be used for prediction since it is based upon observed quantities. Therefore, the relationship was further developed to express DeltaF in terms of expected long-term contributions that are conditional on a set of selective advantages that relate the selection processes in two consecutive generations and are predictable quantities. With random mating, if selected family sizes are assumed to be independent Poisson variables then the expected long-term contribution could be substituted for the observed, providing (1)/(4) (since omega = 0) was increased to (1)/(2). Established theory was used to provide a correction term to account for deviations from the Poisson assumptions. The equations were successfully applied, using simple linear models, to the problem of predicting DeltaF with sib indices in discrete generations since previously published solutions had proved complex. PMID:10747074

Towards the development of high temperature comparison artifacts for radiation thermometry

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

Teixeira, R. N.; Machin, G.; Orlando, A.

This paper describes the methodology and first results of the development of high temperature fixed point artifacts of unknown temperature suitable for scale comparison purposes. This study is being undertaken at the Thermal Metrology Division of Inmetro, Brazil, as part of PhD studies. In this initial phase of the study two identical cobalt carbon eutectic cells were constructed and one doped with a known amount of copper. This was an attempt to achieve a controlled change in the transition temperature of the alloy during melting. Copper was chosen due to the relatively simple phase diagram it forms with carbon andmore » cobalt. The cobalt, in powder form, was supplied by Alfa Aesar at 99.998 % purity, and was mixed with carbon powder (1,9 % by weight) of 99.9999 % purity. Complete filling of the crucible took 6 steps and was performed in a vertical furnace with graphite heating elements, in an inert gas atmosphere. The temperature measurements were performed using a KE LP3 radiation thermometer, which was previously evaluated for spectral responsivity, linearity and size-of-source effect (SSE). During these measurements, the thermometer stability was periodically checked using a silver fixed point blackbody maintained in a three zone furnace. The main purpose of the first part of this study is to dope a series of Co-C blackbody with differing amounts of copper, in order to alter their temperatures whilst still retaining good melting plateau performance. The long-term stability of the adjusted transition temperatures will also be investigated. Other dopants will be studied as the research progresses, and thermo chemical modeling will be performed in an attempt to understand the change in temperature with dopant concentration and so help select suitable dopants in the future. The overall objective is to construct comparison artifacts that have good performance, in terms of plateau shape and long-term temperature stability, but with unknown temperatures. These can then be used as comparison artifacts with no participant, except the pilot, knowing the temperature a priori.« less

Transport, fate, and long-term impacts of metal oxide nanoparticles on the stability of an anaerobic methanogenic system with anaerobic granular sludge.

PubMed

Li, Huiting; Cui, Fuyi; Liu, Zhiquan; Li, Dapeng

2017-06-01

The fate and long-term effect of different metal oxide (TiO 2 , CuO and ZnO) nanoparticles (NPs) on anaerobic granular sludge (AGS) was evaluated in an anaerobic methanogenic system. Operation stability and structural characteristics of the granules were compared, the metabolism changes in the microbial community were quantified, and NPs fate were investigated. CuO NPs had greatest toxic effect on AGS after extended exposure, whereas ZnO NPs benefited methanogenesis temporarily (no more than 5d). The inhibition on AGS caused by NPs varied due to the unique structure of AGS and different toxic mechanism. Structural changes of AGS provided new evidence that tested NPs have different toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investing in Children. Worldwatch Paper 64.

ERIC Educational Resources Information Center

Chandler, William U.

This report emphasizes the need for action in improving human nutrition, health and the status of women in Third World countries. Special attention is directed to improvement in child health care practices. The report advocates a strategy that meshes short term needs of desperate families with long term requirements of ecological stability and…

Formation and stability of synaptic receptor domains.

PubMed

Haselwandter, Christoph A; Calamai, Martino; Kardar, Mehran; Triller, Antoine; da Silveira, Rava Azeredo

2011-06-10

Neurotransmitter receptor molecules, concentrated in postsynaptic domains along with scaffold and a number of other molecules, are key regulators of signal transmission across synapses. Combining experiment and theory, we develop a quantitative description of synaptic receptor domains in terms of a reaction-diffusion model. We show that interactions between only receptors and scaffolds, together with the rapid diffusion of receptors on the cell membrane, are sufficient for the formation and stable characteristic size of synaptic receptor domains. Our work reconciles long-term stability of synaptic receptor domains with rapid turnover and diffusion of individual receptors, and suggests novel mechanisms for a form of short-term, postsynaptic plasticity.

A cell stabilization factor for transport of experimental cell cultures to and from the International Space Station

NASA Astrophysics Data System (ADS)

Fattaey, Heideh K.; Consigli, Richard A.; Grenz, Ladonna; Johnson, Terry C.

2000-01-01

The requirement for long term storage of cell cultures previous to arrival on the International Space Station (ISS), as well as culture maintenance after the conduct of experiment in microgravity, necessitates inhibition of cell proliferation and metabolism pending return to earth-based laboratories. Transport of cells in a nonstabilized condition can lead to a loss of cell viability and/or a source of selection pressures for survival that can alter the overall cell population. We have isolated in our laboratory a reversible inhibitor of cell proliferation, a cell regulatory sialoglycopeptide (CeReS-18), that has the capability of stabilizing cells isolated from a wide phylogenetic range by arresting them in the G1 phase of the cell cycle. We show here that CeReS-18 is unusually stable and can be stored at ambient temperatures for weeks without a measurable loss in its biological activity. In addition we demonstrate that CeReS-18 is a superior cell-stabilizing agent as compared to other methods deployed for cell stabilization purposes, such as, decrease in the incubation temperature and serum down shifts. We also discovered that hybridoma cultures stabilized in their proliferative cycle by CeReS-18 produced 150%-300% more antibody per cell than that measured in the proliferating control cultures. The reversible inhibitory activity of CeReS-18, together with its unusual stability, as well as its wide target range lend themselves to use of this inhibitor as a cell stabilizing agent for cell transport to and storage on the ISS. .

Long-term stable lung function and second uncomplicated pregnancy on sirolimus in lymphangioleiomyomatosis (LAM).

PubMed

Faehling, Martin; Wienhausen-Wilke, Vera; Fallscheer, Sabine; Trinajstic-Schulz, B; Weber, J; Leschke, Matthias

2015-09-14

We present a patient with lymphangioleiomyomatosis (LAM) on long-term sirolimus (now 79 months) who has had a second successful pregnancy. The second pregnancy on uninterrupted low-dose sirolimus (plasma levels 3-5 mg/L) was uncomplicated both with respect to mother and child suggesting that low-dose sirolimus might be safe in selected pregnant patients with stable LAM. The long-term time course in this patient is in agreement with recent reports of a long-term beneficial effect of sirolimus in LAM. In this patient, the pregnancies did not seem to impair the long-term improvement of lung-function on sirolimus.

Planning the Transition to Long-Term Stewardship for the River Corridor

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

Cearlock, C.S.; Lerch, J.A.; Sands, J.P.

2007-07-01

Long-term stewardship refers to all activities necessary to ensure protection of human health and the environment following completion of remediation, disposal, or stabilization of a site or a portion of a site. Efforts to establish the proposed approach and criteria to be met for long-term stewardship in the river corridor of the Hanford Site in Richland, Washington, are currently being established and a draft plan is expected to be completed in mid-2007 to facilitate planning for a smooth and seamless transition to long-term stewardship. Once the initial criteria have been established, supporting information will be gathered as the work proceeds.more » Near the end of cleanup actions under the River Corridor Closure Contract, these criteria will be finalized in a long-term stewardship plan that documents how the criteria have been met. In addition, the final long-term stewardship plan will also contain a proposed Finding of Suitability to Transfer in accordance with Comprehensive Environmental Response, Compensation, and Liability Act of 1980 Section 120(h) [1]. This final long-term stewardship plan will provide the foundation for post-River Corridor Closure Contract and management activities in the river corridor pending actual property transfer from the U.S. Department of Energy. (authors)« less

Extraction and evaluation of gas-flow-dependent features from dynamic measurements of gas sensors array

NASA Astrophysics Data System (ADS)

Kalinowski, Paweł; Woźniak, Łukasz; Jasiński, Grzegorz; Jasiński, Piotr

2016-11-01

Gas analyzers based on gas sensors are the devices which enable recognition of various kinds of volatile compounds. They have continuously been developed and investigated for over three decades, however there are still limitations which slow down the implementation of those devices in many applications. For example, the main drawbacks are the lack of selectivity, sensitivity and long term stability of those devices caused by the drift of utilized sensors. This implies the necessity of investigations not only in the field of development of gas sensors construction, but also the development of measurement procedures or methods of analysis of sensor responses which compensate the limitations of sensors devices. One of the fields of investigations covers the dynamic measurements of sensors or sensor-arrays response with the utilization of flow modulation techniques. Different gas delivery patterns enable the possibility of extraction of unique features which improves the stability and selectivity of gas detecting systems. In this article three utilized flow modulation techniques are presented, together with the proposition of the evaluation method of their usefulness and robustness in environmental pollutants detecting systems. The results of dynamic measurements of an commercially available TGS sensor array in the presence of nitrogen dioxide and ammonia are shown.

A sensitive molecularly imprinted polymer based quartz crystal microbalance nanosensor for selective determination of lovastatin in red yeast rice.

PubMed

Eren, Tanju; Atar, Necip; Yola, Mehmet Lütfi; Karimi-Maleh, Hassan

2015-10-15

Lovastatin (LOV) is a statin, used to lower cholesterol which has been found as a hypolipidemic agent in commercial red yeast rice. In present study, a sensitive molecular imprinted quartz crystal microbalance (QCM) sensor was prepared by fabricating a self-assembling monolayer formation of allylmercaptane on QCM chip surface for selective determination of lovastatin (LOV) in red yeast rice. To prepare molecular imprinted quartz crystal microbalance (QCM) nanosensor, LOV imprinted poly(2-hydroxyethyl methacrylate-methacryloylamidoaspartic acid) [p(HEMA-MAAsp)] nanofilm was attached on the modified gold surface of QCM chip. The non-modified and improved surfaces were characterized by using contact angle, atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. The imprinted QCM sensor was validated according to the ICH guideline (International Conference on Harmonisation). The linearity range was obtained as 0.10-1.25 nM. The detection limit of the prepared material was calculated as 0.030 nM. The developed QCM nanosensor was successfully used to examine red yeast rice. Furthermore, the stability and repeatability of the prepared QCM nanosensor were studied. The spectacular long-term stability and repeatability of the prepared LOV-imprinted QCM nanosensor make them intriguing for use in QCM sensors. Copyright © 2015 Elsevier Ltd. All rights reserved.

The clinical outcome of skeletal anchorage in interceptive treatment (in growing patients) for class III malocclusion.

PubMed

Meyns, J; Brasil, D M; Mazzi-Chaves, J F; Politis, C; Jacobs, R

2018-04-27

A systematic review of the literature was performed regarding the clinical outcome (effectiveness) of bone anchorage devices in interceptive treatment for class III malocclusion. A search of Embase, PubMed and Web of Science databases yielded 285 papers. An additional two articles were retrieved through manual searching of the reference lists. After initial abstract selection, 32 potentially eligible articles were screened in detail, resulting in a final number of eight articles included in this review. Insufficient evidence was found regarding the effects of skeletal anchorage in interceptive class III treatment to support definitive conclusions on long-term skeletal effects and stability. In the short term, it seems that bone anchors can provide more skeletal effect with less dentoalveolar compensations and less unwanted vertical changes. This does not always exclude the use of a face mask. The use of miniscrews as skeletal anchorage device does not seem to provide more skeletal effect, although it could minimize the unwanted dental effects in the upper jaw. No information regarding the need for orthognathic surgery, orthodontic treatment time or patient compliance and complications was found in the selected articles. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Looking Similar Promotes Group Stability in a Game-Based Virtual Community.

PubMed

Lortie, Catherine L; Guitton, Matthieu J

2012-08-01

Online support groups are popular Web-based resources that provide tailored information and peer support through virtual communities and fulfill the users' needs for empowerment and belonging. However, the therapeutic potential of online support groups is at present limited by the lack of systematic research on the cognitive mechanisms underlying social group cohesion in virtual communities. We might increase the benefits of participation in online support groups if we gain more insight into the factors that promote long-term commitment to peer support. One approach to foster the therapeutic potential of online support groups could be to increase social selection based on visual similarity. We performed a case study using the popular virtual setting of "World of Warcraft" (Blizzard Entertainment, Irvine, CA). We monitored the social dynamics of a virtual community composed of avatars whose appearance was identical during a period of 3 months, biweekly, for a total of 24 measures. We observed that this homogeneous community displayed a very high level of group stability over time in terms of the total number of members, the number of members that stayed the same, and the number of arrivals and departures, despite the fact that belonging to a heterogeneous group typically favors the success of the group with respect to game progression. Our results confirm that appearance can trigger social selection in online virtual communities. Displaying a similar appearance could be one way to strengthen social bonds among peers who share various health and well-being issues. Thus, the therapeutic potential of online support groups could be promoted through visual cohesion.

ORTHODONTIC RETENTION. Studies of retention capacity, cost-effectiveness and long-term stability.

PubMed

Tynelius, Gudrun Edman

2014-01-01

Retention strategies, cost-effectiveness and long-term stability of treatment outcome are essential aspects of orthodontic treatment planning. The overall aim of this thesis was to compare and evaluate three different retention strategies, with special reference to short- and long-term clinical stability and cost-effectiveness. The approach was evidence-based, hence randomized controlled methodology was used in order to generate high levels of evidence. This thesis is based on four studies: Papers I and II are based on randomized controlled trials, evaluating the stability of treatment outcome after one and two years of retention, using three different retention strategies: a maxillary vacuum-formed retainer combined with a mandibular canine-to-canine retainer; a maxillary vacuum-formed retainer combined with stripping of the mandibular anterior teeth and a prefabricated positioner. Paper III presents a cost-minimization analysis of two years of retention treatment. Paper IV is based on a randomized controlled trial documenting the results five years post-retention. The following conclusions were drawn: Papers I and II. From a clinical perspective, asssessment after one year of retention disclosed that the three retention methods were successful in retaining the orthodontic treatment results. After two years of retention, all three retention methods were equally effective in controlling relapse at a clinically acceptable level. Most of the relapse occurred during the first year of retention; only minor or negligible changes were found during the second year. The subjects were grouped according to the level of compliance (excellent or good). After two years of retention there was a negative correlation between growth in body height and relapse of mandibular LII in the group of subjects with excellent compliance. The group with good compliance showed a positive correlation (Paper II, Figure 3). After two years of retention, growth in body height, initial crowding and gender had no significant influence on mandibular LII (Paper II, Figure 4 and Table 4). Paper III. The cost minimization analysis disclosed that although the three retention methods achieved clinically similar results, the associated societal costs differed. After two years of retention, the vacuum-formed retainer (VFR) in combination with a canine-to-canine retainer (CTC) was the least cost-effective retention appliance. Paper IV. After five years or more out of retention, the three retention methods had achieved equally favourable clinical results. Key conclusion and clinical implications. This study compared the short- and long-term outcomes of orthodontic retention by three different methods: a maxillary vacuum-formed retainer combined with a mandibular canine-to-canine retainer; a maxillary vacuum-formed retainer combined with stripping of the mandibular anterior teeth and a prefabricated positioner. All methods gave equally positive clinical results in both the short-term, i.e. after one and two years of retention, and in the long-term, five years or more post-retention. After two years of retention, the level of compliance affected the retention treatment result. However, no such effect was shown for body height, the severity of initial crowding or gender. Today, there is increasing emphasis on the importance of economic aspects of healthcare. Of the three methods evaluated in this study, the least cost-effective, after two years of retention, was a vacuum-formed retainer combined with a bonded canine-to-canine retainer. The clinical implication of this finding is that in patients meeting the inclusion criteria, interproximal stripping of the mandibular anterior teeth, or the use of a prefabricated positioner, are highly appropriate alternatives to a mandibular bonded canine-to-canine retainer. The overall conclusions are that there are a number of effective retention methods available and the clinician is not limited to routine use of a bonded mandibular canine-to-canine retainer. The most appropriate retention method should be selected on an individual, case to case basis, taking into account such variables as orthodontic diagnosis, the expected level of patient compliance, patient preferences and financial considerations.

Progress on plutonium stabilization

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

Hurt, D.

1996-05-01

The Defense Nuclear Facilities Safety Board has safety oversight responsibility for most of the facilities where unstable forms of plutonium are being processed and packaged for interim storage. The Board has issued recommendations on plutonium stabilization and has has a considerable influence on DOE`s stabilization schedules and priorities. The Board has not made any recommendations on long-term plutonium disposition, although it may get more involved in the future if DOE develops plans to use defense nuclear facilities for disposition activities.

Stable Carboxylate-Terminated Gold Surfaces Produced by Spontaneous Grafting of an Alkyl Tin Compound.

PubMed

Ortiz, Mayreli; Mehdi, Ahmed; Methivier, Christophe; Thorimbert, Serge; Hasenknopf, Bernold; O'Sullivan, Ciara K

2018-05-21

Self-assembled monolayers formed by chemisorption of thiolated molecules on gold surfaces are widely applied for biosensing. Moreover, and due to the low stability of thiol-gold chemistry, contributions to the functionalisation of gold substrates with linkers that provide a more stable platform for the immobilisation of electroactive or biological molecules are highly appreciated. In the work reported here, we demonstrate that a carboxylated organotin compound can be successfully grafted onto gold substrates to form a highly stable organic layer with reactivity for subsequent binding to an aminated molecule. A battery of techniques was used to characterise the surface chemistry. The grafted layer was used to anchor aminoferrocene and subjected to both thermostability tests and long term stability studies over the period of one year, demonstrating thermostability up to 90 oC and storage stability for at least 12 months when stored at 4 oC protected from light. The stable surface tethering of molecules on gold substrates can be exploited in a plethora of applications including molecular techniques such as solid-phase amplification and solid-phase melting curve analysis that require elevated temperature stability, as well as biosensors, which require long-term storage stability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.